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Sample records for microa cm-2 mm-1

  1. Physics at 1034 cm-2 s-1

    International Nuclear Information System (INIS)

    Diebold, R.; Wagner, R.

    1984-01-01

    Most of the detector studies at Snowmass-84 have rightfully concentrated on detailed studies of individual interactions - their rates, signatures, and backgrounds. Depending on the physics and the detector components, there seems to be agreement that general-purpose detectors will likely be able to accept luminosities up to 10 32-33 cm -2 s -1 . The purpose of this paper is to show how the physics reach of the SSC is extended by going to a luminosity of 10 34 cm -2 s -1 , to take a first look at what sort of detector could be used at this luminosity, and to discuss how one might trigger on interesting events in the presence of many overlapping minimum bias events. We will assume that the SSC turns on at 10 31 or 10 32 cm -2 s -1 , with an increase of luminosity to 10 33 over a period of a few years as the machine and detectors become better understood. Thus, the lower mass scale will have been explored and we can set our thresholds high when running 10 34

  2. Sporadic Creutzfeldt-Jakob Disease MM1+2C and MM1 are Identical in Transmission Properties.

    Science.gov (United States)

    Kobayashi, Atsushi; Matsuura, Yuichi; Iwaki, Toru; Iwasaki, Yasushi; Yoshida, Mari; Takahashi, Hitoshi; Murayama, Shigeo; Takao, Masaki; Kato, Shinsuke; Yamada, Masahito; Mohri, Shirou; Kitamoto, Tetsuyuki

    2016-01-01

    The genotype (methionine, M or valine, V) at polymorphic codon 129 of the PRNP gene and the type (1 or 2) of abnormal prion protein in the brain are the major determinants of the clinicopathological features of sporadic Creutzfeldt-Jakob disease (CJD), thus providing molecular basis for classification of sporadic CJD, that is, MM1, MM2, MV1, MV2, VV1 or VV2. In addition to these "pure" cases, "mixed" cases presenting mixed neuropathological and biochemical features have also been recognized. The most frequently observed mixed form is the co-occurrence of MM1 and MM2, namely MM1+2. However, it has remained elusive whether MM1+2 could be a causative origin of dura mater graft-associated CJD (dCJD), one of the largest subgroups of iatrogenic CJD. To test this possibility, we performed transmission experiments of MM1+2 prions and a systematic neuropathological examination of dCJD patients in the present study. The transmission properties of the MM1+2 prions were identical to those of MM1 prions because MM2 prions lacked transmissibility. In addition, the neuropathological characteristics of MM2 were totally absent in dCJD patients examined. These results suggest that MM1+2 can be a causative origin of dCJD and causes neuropathological phenotype similar to that of MM1. © 2015 International Society of Neuropathology.

  3. CM-2 Environmental/Modal Testing of SPACEHAB Racks

    Science.gov (United States)

    McNelis, Mark E.; Goodnight, Thomas W.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.

  4. Visualizing quantum scattering on the CM-2 supercomputer

    International Nuclear Information System (INIS)

    Richardson, J.L.

    1991-01-01

    We implement parallel algorithms for solving the time-dependent Schroedinger equation on the CM-2 supercomputer. These methods are unconditionally stable as well as unitary at each time step and have the advantage of being spatially local and explicit. We show how to visualize the dynamics of quantum scattering using techniques for visualizing complex wave functions. Several scattering problems are solved to demonstrate the use of these methods. (orig.)

  5. The NAP flux at mountain altitude 725 g cm-2

    International Nuclear Information System (INIS)

    Hazama, M.

    1977-01-01

    The energy spectrum of nuclear active particles (NAP) with energy ΣEsub(γ) greater than 3 TeV is obtained from an analysis of a thick emulsion chamber (140 cu of Pb) exposed on Mount Norikura at 2770 m above sea level and the vertical flux is estimated to be (1.4 +- 0.1) x 10 -10 cm -2 s -1 sr -1 . Assuming that the energy spectrum and the zenith angle distribution of NAP are expressed by power functions proportional to Esup(-(γ + 1)) and cossup(n-2) theta respectively in differential form, the exponents γ and n are obtained as 2.3 +- 0.1 and 7.3 +- 0.5 respectively. The collision mean free path and the ratio of constituents of NAP are discussed. (author)

  6. SUBMILLIMETER ARRAY OBSERVATIONS TOWARD THE MASSIVE STAR-FORMING CORE MM1 OF W75N

    International Nuclear Information System (INIS)

    Minh, Y. C.; Su, Y.-N.; Liu, S.-Y.; Yan, C.-H.; Chen, H.-R.; Kim, S.-J.

    2010-01-01

    The massive star-forming core MM1 of W75N was observed using the Submillimeter Array with ∼1'' and 2'' spatial resolutions at 217 and 347 GHz, respectively. From the 217 GHz continuum we found that the MM1 core consists of two sources, separated by about 1'': MM1a (∼0.6 M sun ) and MM1b (∼1.4 M sun ), located near the radio continuum sources VLA 2/VLA 3 and VLA 1, respectively. Within MM1b, two gas clumps were found to be expanding away from VLA 1 at about ±3 km s -1 , as a result of the most recent star formation activity in the region. Observed molecular lines show emission peaks at two positions, MM1a and MM1b: sulfur-bearing species have emission peaks toward MM1a, but methanol and saturated species at MM1b. We identified high-temperature (∼200 K) gas toward MM1a and the hot core in MM1b. This segregation may result from the evolution of the massive star-forming core. In the very early phase of star formation, the hot core is seen through the evaporation of dust ice-mantle species. As the mantle species are consumed via evaporation the high-temperature gas species (such as the sulfur-bearing molecules) become bright. The SiO molecule is unique in having an emission peak exactly at the VLA 2 position, probably tracing a shock powered by VLA 2. The observed sulfur-bearing species show similar abundances both in MM1a and MM1b, whereas the methanol and saturated species show significant abundance enhancement toward MM1b, by about an order of magnitude, compared to MM1a.

  7. Molecular cloning and analysis of Myc modulator 1 (Mm-1 from Bufo gargarizans (Amphibia: Anura

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2010-02-01

    Full Text Available The protein of Myc modulator 1 (Mm-1 has been reported to repress the transcriptional activity of the proto-oncogene c-Myc in humans. Moreover, it was shown to be the subunit 5 of human prefoldin (PFD. So far, this gene and its homologs have been isolated and sequenced in many organisms, such as mammals and fish, but has not been sequenced for any amphibian or reptile. In order to better understand the function and evolution of Mm-1, we isolated a full-length Mm-1 cDNA (BgMm-1, GenBank accession no. EF211947 from Bufo gargarizans (Cantor, 1842 using RACE (rapid amplification of cDNA ends methods. Mm-1 in B. gargarizans is 755 bp long, comprising an open reading frame (ORF of 459 bp encoding 152 amino acids. The amino acid sequence had a prefoldin α-like domain, partially including a typical putative leucine zipper motif. BgMm-1 showed high similarity to its homolog of Mus musculus Linnaeus, 1758 (82% and Homo sapiens Linnaeus, 1758 MM-1 isoform a (81% at the amino acid level. The protein secondary structure modeled with the SWISS MODEL server revealed that there were two α-helices and four b-strands in BgMm-1 as its human orthologue, and both proteins belonged to the a class of PFD family. The phylogenetic relationships of Mm-1s from lower archaea to high mammals was consistent with the evolution of species, meanwhile the cluster result was consistent with the multiple alignment and the sequence identity analysis. RT-PCR (reverse transcriptase-polymerase chain reaction analysis demonstrated that BgMm-1 expressed widely in ten tissues of adult toad. These results can be helpful for the further investigation on the evolution of Mm-1.

  8. GFDL CM2.1 Global Coupled Ocean-Atmosphere Model Water ...

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. GFDL CM2.1 Global Coupled Ocean-Atmosphere Model Water Hosing Experiment with 1 Sv equivalent of Freshening Control Expt: 100 yrs After Hosing: 300 yrs.

  9. GFDL's CM2 global coupled climate models. Part I: Formulation and simulation characteristics

    Science.gov (United States)

    Delworth, T.L.; Broccoli, A.J.; Rosati, A.; Stouffer, R.J.; Balaji, V.; Beesley, J.A.; Cooke, W.F.; Dixon, K.W.; Dunne, J.; Dunne, K.A.; Durachta, J.W.; Findell, K.L.; Ginoux, P.; Gnanadesikan, A.; Gordon, C.T.; Griffies, S.M.; Gudgel, R.; Harrison, M.J.; Held, I.M.; Hemler, R.S.; Horowitz, L.W.; Klein, S.A.; Knutson, T.R.; Kushner, P.J.; Langenhorst, A.R.; Lee, H.-C.; Lin, S.-J.; Lu, J.; Malyshev, S.L.; Milly, P.C.D.; Ramaswamy, V.; Russell, J.; Schwarzkopf, M.D.; Shevliakova, E.; Sirutis, J.J.; Spelman, M.J.; Stern, W.F.; Winton, M.; Wittenberg, A.T.; Wyman, B.; Zeng, F.; Zhang, R.

    2006-01-01

    The formulation and simulation characteristics of two new global coupled climate models developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) are described. The models were designed to simulate atmospheric and oceanic climate and variability from the diurnal time scale through multicentury climate change, given our computational constraints. In particular, an important goal was to use the same model for both experimental seasonal to interannual forecasting and the study of multicentury global climate change, and this goal has been achieved. Tw o versions of the coupled model are described, called CM2.0 and CM2.1. The versions differ primarily in the dynamical core used in the atmospheric component, along with the cloud tuning and some details of the land and ocean components. For both coupled models, the resolution of the land and atmospheric components is 2?? latitude ?? 2.5?? longitude; the atmospheric model has 24 vertical levels. The ocean resolution is 1?? in latitude and longitude, with meridional resolution equatorward of 30?? becoming progressively finer, such that the meridional resolution is 1/3?? at the equator. There are 50 vertical levels in the ocean, with 22 evenly spaced levels within the top 220 m. The ocean component has poles over North America and Eurasia to avoid polar filtering. Neither coupled model employs flux adjustments. The co ntrol simulations have stable, realistic climates when integrated over multiple centuries. Both models have simulations of ENSO that are substantially improved relative to previous GFDL coupled models. The CM2.0 model has been further evaluated as an ENSO forecast model and has good skill (CM2.1 has not been evaluated as an ENSO forecast model). Generally reduced temperature and salinity biases exist in CM2.1 relative to CM2.0. These reductions are associated with 1) improved simulations of surface wind stress in CM2.1 and associated changes in oceanic gyre circulations; 2) changes in cloud tuning and

  10. Transient analysis of an M/M/1 queue with multiple vacations

    Directory of Open Access Journals (Sweden)

    Kaliappan Kalidass

    2014-05-01

    Full Text Available In this paper, we have obtained explicit expressions for the time dependent probabilities of the M/M/1  queue with server vacations under a multiple vacation scheme. The corresponding steady state probabilities have been obtained. We also obtain the time dependent performance measures of the systems

  11. A Busy period analysis for the state dependent M/M/1/K queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Boxma, Onno

    2010-01-01

    In this paper, we study the transient behavior of a state dependent M/M/1/K queue during the busy period. We derive in closed-form the joint transform of the length of the busy period, the number of customers served during the busy period, and the number of losses during the busy period. For two

  12. 4-CM2 CuInGaSe2 based solar cells

    International Nuclear Information System (INIS)

    Devaney, W.E.; Stewart, J.M.; Chen, W.S.

    1990-01-01

    This paper reports that polycrystalline thin-film solar cells with the structure ZnO/CdZnS/CuInGaSe 2 have been fabricated with larger single cell areas than have been previously reported. A cell of area 4-cm 2 has been made with an Am1.5, 100 mW/cm 2 total area conversion efficiency of (11.1% 912.0% active area) and AMO conversion efficiency of 10.0% (10.9% active area). The CuInGaSe 2 layer had a gallium to indium ratio of 0.26:0.74 with a band gap of approximately 1.15 eV. The cells use an isolated tab design for the negative (grid) contact, demonstrating the ability to pattern the semiconductor layers. Such CuInGaSe 2 based cells may be suitable both for large area terrestrial applications and for single-junction space cell applications

  13. Uniform laser ablative acceleration of targets at 1014 W/cm2

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Whitlock, R.R.; McLean, E.A.; Ripin, B.H.; Price, R.H.; Phillion, D.W.; Campbell, E.M.; Rosen, M.D.

    1982-01-01

    We present the first detailed investigations of the ablative acceleration of planar targets while simultaneously using high irradiance (10 14 W/cm 2 ), large focal diameters (1 mm) and long laser pulse duration (3 nsec). Included are measurements of target preheat, ablation pressures and uniformity achieved under these conditions. Targets were accelerated to high velocities with velocity profile uniformity approaching that required for high gain pellet implosions

  14. Survival and photoreactivability of ultraviolet-irradiated cultured fish cells (CAF-MM1)

    International Nuclear Information System (INIS)

    Mano, Y.; Mitani, H.; Etoh, H.; Egami, N.

    1980-01-01

    The sensitivity to ultraviolet light (uv) and photoreactivating ability of cultured fish clone cells (CAF-MM1) were investigated. Dose-survival relationship curves were obtained using the colony-forming technique at various postirradiation temperatures (33, 26, and 20 0 C). At 26 0 C the values of D 0 , D/sub q/, and the extrapolation number (n) were 1.74 J/m 2 , 2.62 J/m 2 , and 4.5, respectively; no marked differences in these values were found among different temperatures. Visible light illumination after uv irradiation produced a marked increase in survival. No photoreactivation effects were observed beyond about 30 h. Caffeine increased uv sensitivity of the CAF-MM1 cells, and from the results it is suggested that the cells have some caffeine-sensitive dark repair mechanisms

  15. MM1+2C sporadic Creutzfeldt-Jakob disease presenting as rapidly progressive nonfluent aphasia.

    Science.gov (United States)

    Allegri, Ricardo F; Bartoloni, Leonardo; Iturry, Mónica; Romero, Carlos; Begué, Christián; Sevlever, Gustavo; Taratuto, Ana Lía

    2014-01-01

    We report a 77-year-old man, presenting with progressive aphasia as an initial symptom, who developed severe dementia over the course of 20 months. Frontal cortex PrPSc western blot was type 2 and codon 129 was MM; brain neuropathology showed cortical vacuoles with perivacuolar PrP immunostaining characteristic of MM2C. Cerebellum showed focal coarse, patchy staining in different sections of the molecular layer, diffuse fine punctuate and coarse PrP immunopositive deposits in the granule cell layer, and focal synaptic immunostaining in the molecular layer, suggestive of MM1+2C by histotyping. This clinical presentation has not yet been described in an MM1+2C subtype by histotyping.

  16. Studies of flow configurations up to the critical phenomenon at 80 kg/cm2

    International Nuclear Information System (INIS)

    Raisson, C.

    1968-12-01

    Tests performed at 80 kg/cm 2 allow to study two-phase flows and their evolution up to the critical heating. Three measurement methods have been used simultaneously: thermocouples, conductivity probe, short length pressure drops after the output. The 282 cm length stainless steel channel has an internal diameter of 0.6 cm and a wall thickness of 0.2 cm. Flow configuration results are comparable to those of the literature with some precision regarding some transition zones. Two critical heating regimes have been highlighted. The results demonstrate the interest of the method and the importance of hydrodynamic parameters on the critical heating phenomenon [fr

  17. The M/M/1 queue with inventory, lost sale and general lead times

    DEFF Research Database (Denmark)

    Saffari, Mohammad; Asmussen, Søren; Haji, Rasoul

    We consider an M/M/1 queueing system with inventory under the (r,Q) policy and with lost sales, in which demands occur according to a Poisson process and service times are exponentially distributed. All arriving customers during stockout are lost. We derive the stationary distributions of the joint...... queue length (number of customers in the system) and on-hand inventory when lead times are random variables and can take various distributions. The derived stationary distributions are used to formulate long-run average performance measures and cost functions in some numerical examples....

  18. LHCb Upgrades and operation at 1034 cm-2 s-1 luminosity –A first study

    CERN Document Server

    Efthymiopoulos, Ilias; Baglin, Vincent; Burkhardt, Helmut; Cerutti, Francesco; Claudet, Serge; Di Girolamo, Beniamino; De Maria, Riccardo; Esposito, Luigi Salvatore; Karastathis, Nikos; Lindner, Rolf; Papaphilippou, Yannis; Pellegrini, Dario; Redaelli, Stefano; Roesler, Stefan; Sanchez Galan, Francisco; Thomas, Eric; Tsinganis, Andrea; Wollmann, Daniel; Wilkinson, Guy; Schwarz, Philip; CERN. Geneva. ATS Department

    2018-01-01

    Presently, the LHCb experiment at IP8 operates at reduced luminosity (~4.0 1032 cm-2 s-1) compared to ATLAS and CMS experiments. The LHCb collaboration is proposing an Upgrade II during HL-LHC operation, where the beams at IP8 will collide at high-luminosity (~1-2 1034 cm-2 s-1), comparable to the present high-luminosity regions IP1&IP5. The LHCb experiment aims to collect more than 300 fb-1 by the end of the HL-LHC operation. A feasibility study of operating IP8 at high-luminosity whilst preserving the performance at IP1 and IP5 and on the impact to the LHC machine and experimental cavern was done. Optics studies shows that solutions allowing to reach an integrated luminosity of 40 to 50 fb-1 per year to LHCb/IP8 at the cost of a reduction of about 5% in the integrated luminosity of the main experiments ATLAS and CMS, under the assumption that there are no lifetime limitations besides burn-off, are feasible. Energy deposition in the machine elements of the IR straight section 8 and LHC infrastructure and...

  19. THz Induced Nonlinear Effects in Materials at Intensities above 26 GW/cm2

    Science.gov (United States)

    Woldegeorgis, A.; Kurihara, T.; Beleites, B.; Bossert, J.; Grosse, R.; Paulus, G. G.; Ronneberger, F.; Gopal, A.

    2018-04-01

    Nonlinear refractive index and absorption coefficient are measured for common semiconductor material such as silicon and organic molecule such as lactose in the terahertz (THz) spectral regime extending from 0.1 to 3 THz. Terahertz pulses with field strengths in excess of 4.4 MV/cm have been employed. Transmittance and the transmitted spectrum were measured with Z-scan and single shot noncollinear electro-optic pump-probe techniques. The THz-induced change in the refractive index (Δn) shows frequency-dependence and a maximum change of - 0.128 at 1.37 THz in lactose and up to + 0.169 at 0.15 THz in silicon was measured for a peak incident THz intensity of 26 GW/cm2. Furthermore, the refractive index variation shows a quadratic dependence on the incident THz field, implying the dominance of third-order nonlinearity.

  20. Optimization of an M/M/1/N Feedback Queue with Retention of Reneged Customers

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2014-01-01

    Full Text Available Customer impatience has become a threat to the business world. Firms employ various customer retention strategies to retain their impatient (or reneged customers. Customer retention mechanisms may help to retain some or all impatient customers. Further, due to unsatisfactory service, customers may rejoin a queue immediately after departure. Such cases are referred to as feedback customers. Kumar and Sharma take this situation into account and study an M/M/1/N feedback queuing system with retention of reneged customers. They obtain only a steady-state solution for this model. In this paper, we extend the work of Kumar and Sharma by performing an economic analysis of the model. We develop a model for the costs incurred and perform the appropriate optimization. The optimum system capacity and optimum service rate are obtained. (original abstract

  1. On the Behavior of Phosphorus During the Aqueous Alteration of CM2 Carbonaceous Chondrites

    Science.gov (United States)

    Brearley, Adrian J.; Chizmadia, Lysa J.

    2005-01-01

    During the earliest period of solar system formation, water played an important role in the evolution of primitive dust, both after accretion of planetesimals and possible before accretion within the protoplanetary disk. Many chondrites show evidence of variable degrees of aqueous alteration, the CM2 chondrites being among the most studied [1]. This group of chondrites is characterized by mineral assemblages of both primary and secondary alteration phases. Hence, these meteorites retain a particularly important record of the reactions that occurred between primary high temperature nebular phases and water. Studies of these chondrites can provide information on the conditions and environments of aqueous alteration and the mobility of elements during alteration. This latter question is at the core of a debate concerning the location of aqueous alteration, i.e. whether alteration occurred predominantly within a closed system after accretion (parent body alteration) or whether some degree of alteration occurred within the solar nebula or on ephemeral protoplanetary bodies prior to accretion. At the core of the parent body alteration model is the hypothesis that elemental exchange between different components, principally chondrules and matrix, must have occurred. chondrules and matrix, must have occurred. In this study, we focus on the behavior of the minor element, phosphorus. This study was stimulated by observations of the behavior of P during the earliest stages of alteration in glassy mesostasis in type II chondrules in CR chondrites and extends the preliminary observations of on Y791198 to other CM chondrites.

  2. Estimating Convection Parameters in the GFDL CM2.1 Model Using Ensemble Data Assimilation

    Science.gov (United States)

    Li, Shan; Zhang, Shaoqing; Liu, Zhengyu; Lu, Lv; Zhu, Jiang; Zhang, Xuefeng; Wu, Xinrong; Zhao, Ming; Vecchi, Gabriel A.; Zhang, Rong-Hua; Lin, Xiaopei

    2018-04-01

    Parametric uncertainty in convection parameterization is one major source of model errors that cause model climate drift. Convection parameter tuning has been widely studied in atmospheric models to help mitigate the problem. However, in a fully coupled general circulation model (CGCM), convection parameters which impact the ocean as well as the climate simulation may have different optimal values. This study explores the possibility of estimating convection parameters with an ensemble coupled data assimilation method in a CGCM. Impacts of the convection parameter estimation on climate analysis and forecast are analyzed. In a twin experiment framework, five convection parameters in the GFDL coupled model CM2.1 are estimated individually and simultaneously under both perfect and imperfect model regimes. Results show that the ensemble data assimilation method can help reduce the bias in convection parameters. With estimated convection parameters, the analyses and forecasts for both the atmosphere and the ocean are generally improved. It is also found that information in low latitudes is relatively more important for estimating convection parameters. This study further suggests that when important parameters in appropriate physical parameterizations are identified, incorporating their estimation into traditional ensemble data assimilation procedure could improve the final analysis and climate prediction.

  3. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    Science.gov (United States)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We

  4. Patch testing with 2.0% (0.60 mg/cm2) formaldehyde instead of 1.0% (0.30 mg/cm2) detects significantly more contact allerg

    DEFF Research Database (Denmark)

    Pontén, Ann; Aalto-Korte, Kristiina; Agner, Tove

    2013-01-01

    .To validate earlier patch test results for comparison of 1% (wt/vol) and 2% (wt/vol) formaldehyde in water, and to investigate co-reactivity with quaternium-15. Materials and methods.In 12 dermatology clinics, 3591 patients were routinely patch tested simultaneously with 2.0% (wt/vol) (0.60 mg/cm(2) ) and 1.......0% (wt/vol) (0.30 mg/cm(2) ) formaldehyde. Micropipettes were used for delivering the exact dosage of the allergen. Results.Significantly more patients reacted to 2.0% formaldehyde than to 1.0% (3.4% versus 1.8%, p

  5. The centrosomin CM2 domain is a multi-functional binding domain with distinct cell cycle roles.

    Science.gov (United States)

    Citron, Y Rose; Fagerstrom, Carey J; Keszthelyi, Bettina; Huang, Bo; Rusan, Nasser M; Kelly, Mark J S; Agard, David A

    2018-01-01

    The centrosome serves as the main microtubule-organizing center in metazoan cells, yet despite its functional importance, little is known mechanistically about the structure and organizational principles that dictate protein organization in the centrosome. In particular, the protein-protein interactions that allow for the massive structural transition between the tightly organized interphase centrosome and the highly expanded matrix-like arrangement of the mitotic centrosome have been largely uncharacterized. Among the proteins that undergo a major transition is the Drosophila melanogaster protein centrosomin that contains a conserved carboxyl terminus motif, CM2. Recent crystal structures have shown this motif to be dimeric and capable of forming an intramolecular interaction with a central region of centrosomin. Here we use a combination of in-cell microscopy and in vitro oligomer assessment to show that dimerization is not necessary for CM2 recruitment to the centrosome and that CM2 alone undergoes significant cell cycle dependent rearrangement. We use NMR binding assays to confirm this intramolecular interaction and show that residues involved in solution are consistent with the published crystal structure and identify L1137 as critical for binding. Additionally, we show for the first time an in vitro interaction of CM2 with the Drosophila pericentrin-like-protein that exploits the same set of residues as the intramolecular interaction. Furthermore, NMR experiments reveal a calcium sensitive interaction between CM2 and calmodulin. Although unexpected because of sequence divergence, this suggests that centrosomin-mediated assemblies, like the mammalian pericentrin, may be calcium regulated. From these results, we suggest an expanded model where during interphase CM2 interacts with pericentrin-like-protein to form a layer of centrosomin around the centriole wall and that at the onset of mitosis this population acts as a nucleation site of intramolecular

  6. Nanoimprinted polymer lasers with threshold below 100 W/cm2 using mixed-order distributed feedback resonators.

    Science.gov (United States)

    Wang, Yue; Tsiminis, Georgios; Kanibolotsky, Alexander L; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

    2013-06-17

    Organic semiconductor lasers were fabricated by UV-nanoimprint lithography with thresholds as low as 57 W/cm(2) under 4 ns pulsed operation. The nanoimprinted lasers employed mixed-order distributed feedback resonators, with second-order gratings surrounded by first-order gratings, combined with a light-emitting conjugated polymer. They were pumped by InGaN LEDs to produce green-emitting lasers, with thresholds of 208 W/cm(2) (102 nJ/pulse). These hybrid lasers incorporate a scalable UV-nanoimprint lithography process, compatible with high-performance LEDs, therefore we have demonstrated a coherent, compact, low-cost light source.

  7. Hydration and transparency of the rabbit cornea irradiated with UVB-doses of 0.25 J/cm(2) and 0.5 J/cm(2) compared with equivalent UVB radiation exposure reaching the human cornea from sunlight.

    Science.gov (United States)

    Cejka, Cestmír; Ardan, Taras; Sirc, Jakub; Michálek, Jiří; Beneš, Jiří; Brůnová, Blanka; Rosina, Jozef

    2011-07-01

    Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2). Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.

  8. SOFIA MID-INFRARED IMAGING AND CSO SUBMILLIMETER POLARIMETRY OBSERVATIONS OF G034.43+00.24 MM1

    International Nuclear Information System (INIS)

    Jones, T. J.; Gordon, Michael; Shenoy, Dinesh; Gehrz, R. D.; Vaillancourt, John E.; Krejny, M.

    2016-01-01

    We present 11.1 to 37.1 μ m imaging observations of the very dense molecular cloud core MM1 in G034.43+00.24 using FORCAST on SOFIA and submillimeter (submm) polarimetry using SHARP on the Caltech Submillimeter Observatory. We find that at the spatial resolution of SOFIA, the point-spread function (PSF) of MM1 is consistent with being a single source, as expected based on millimeter (mm) and submm observations. The spectral energy distributions (SEDs) of MM1 and MM2 have a warm component at the shorter wavelengths not seen in mm and submm SEDs. Examination of H(1.65 μ m) stellar polarimetry from the Galactic Plane Infrared Polarization Survey shows that G034 is embedded in an external magnetic field aligned with the Galactic Plane. The SHARP polarimetry at 450 μ m shows a magnetic field geometry in the vicinity of MM1 that does not line up with either the Galactic Plane or the mean field direction inferred from the CARMA interferometric polarization map of the central cloud core, but is perpendicular to the long filament in which G034 is embedded. The CARMA polarimetry does show evidence for grain alignment in the central region of the cloud core, and thus does trace the magnetic field geometry near the embedded Class 0 YSO.

  9. Uranium sandwich targets of 0.1 to 100 mg.cm-2 prepared by electron beam gun evaporation

    International Nuclear Information System (INIS)

    Folger, H.; Klemm, J.

    1978-01-01

    Metallic uranium layers of 0.1 to 100 mg.cm -2 between different backings and protecting layers were prepared for bombardments with heavy ions such as argon, krypton, xenon, lead, or uranium at energies of up to 8 MeV/u at the UNILAC of the GSI. An experimental set-up for the preparation of thick and oxygen-free sandwich targets using a 6 kVA electron beam gun was installed in a high vacuum apparatus. Then deposition and evaporation rates for uranium were investigated as a function of the electron beam gun power. It turned out that reproducible evaporation rates of up to 7 mg.s -1 were achieved when uranium pieces of 20 to 40 grams were used. Specific evaporation rates and vapor pressures for different temperatures were calculated. Some of these data are compared to measured values, especially evaporation rates at the evaporation point. The preparation, composition, and usage of uranium sandwich targets is described in detail. It concerns uranium layers of 0.1 to 100 mg.cm -2 deposited onto backings of carbon, titanium, nickel, gold, or glass. Evaporated films of carbon, titanium, nickel, or gold of 0.01 to 0.2 mg.cm -2 are used to protect the uranium layers from oxidation

  10. Measurement of the factor of dispersion in air for a field of 0,8* 8,0 CM 2

    International Nuclear Information System (INIS)

    Gomez-Tejedor Alonso, S.; Huertas Martinez, C.; Penedo Cobos, J. M.; Garcia Castejon, M. A.; Rincon Perezx, M.

    2013-01-01

    The measures of this factor of dispersion in air is usually performed with an ionization chamber cover a cap of balance of such thickness that is achieved the electronic balance, and must be covered completely the CAP by the radiation field. This procedure is not applicable for small fields. The need to measure the Sc of a field of 0.8 * 0.8 cm 2 for a new system of planning led us to try another measure procedure proposed in the literature, using detectors of semiconductor with a sheet of cerrobend by way of balance Cap. (Author)

  11. An Extraordinary Outburst in the Massive Protostellar System NGC 6334I-MM1: Quadrupling of the Millimeter Continuum

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, T. R.; Brogan, C. L.; Indebetouw, R. [NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States); MacLeod, G. [Hartebeesthoek Radio Astronomy Observatory, P.O. Box 443, Krugersdorp 1740 (South Africa); Cyganowski, C. J. [SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom); Chandler, C. J. [NRAO, P.O. Box O, Socorro, NM 87801 (United States); Chibueze, J. O. [Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Carver Building, 1 University Road, Nsukka (Nigeria); Friesen, R. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Thesner, C. [Centre for Space Research, Physics Department, North-West University, Potchefstroom 2520 (South Africa); Young, K. H., E-mail: thunter@nrao.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-03-10

    Based on sub-arcsecond Atacama Large Millimeter/submillimeter Array (ALMA) and Submillimeter Array (SMA) 1.3 mm continuum images of the massive protocluster NGC 6334I obtained in 2015 and 2008, we find that the dust emission from MM1 has increased by a factor of 4.0 ± 0.3 during the intervening years, and undergone a significant change in morphology. The continuum emission from the other cluster members (MM2, MM4, and the UCH ii region MM3 = NGC 6334F) has remained constant. Long-term single-dish maser monitoring at HartRAO finds that multiple maser species toward NGC 6334I flared beginning in early 2015, a few months before our ALMA observation, and some persist in that state. New ALMA images obtained in 2016 July–August at 1.1 and 0.87 mm confirm the changes with respect to SMA 0.87 mm images from 2008, and indicate that the (sub)millimeter flaring has continued for at least a year. The excess continuum emission, centered on the hypercompact H ii region MM1B, is extended and elongated (1.″6 × 1.″0 ≈ 2100 × 1300 au) with multiple peaks, suggestive of general heating of the surrounding subcomponents of MM1, some of which may trace clumps in a fragmented disk rather than separate protostars. In either case, these remarkable increases in maser and dust emission provide direct observational evidence of a sudden accretion event in the growth of a massive protostar yielding a sustained luminosity surge by a factor of 70 ± 20, analogous to the largest events in simulations by Meyer et al. This target provides an excellent opportunity to assess the impact of such a rare event on a protocluster over many years.

  12. Transient solution of an M/M/1 vacation queue with a waiting server and impatient customers

    Directory of Open Access Journals (Sweden)

    Sherif I. Ammar

    2017-07-01

    Full Text Available Recently, Ammar [1] has discussed the transient behavior of a multiple vacations queue with impatient customers. In this paper, a similar technique is used to derive a new elegant explicit solution for an M/M/1 vacation queue with impatient customers and a waiting server, where the server is allowed to take a vacation whenever the system is empty after waiting for a random period of time. If the server does not return from the vacation before the expiry of the customer impatience time, the customer abandons the system forever. Moreover, the formulas of mean and variance expressed in terms of the obtained possibilities for this model.

  13. Charpy impact test results of ferritic alloys at a fluence of 6 x 1022n/cm2

    International Nuclear Information System (INIS)

    Hu, W.L.

    1985-01-01

    Charpy impact tests on specimens in the AD-2 reconstitution experiment were completed. One hundred ten specimens made of HT-9 base metal, 9Cr-1Mo base metal and 9Cr-1Mo weldment at various heat treatment conditions were tested in temperature range from -73 0 C to 260 0 C. The specimens were irradiated from 390 0 C to 550 0 C and the fluence of the specimens reached 6 x 10 22 n/cm 2 . This is the first time that the transition behavior of ferritic alloys at high fluence was obtained. This is also the first time that comprehensive results on the irradiated 9Cr-1Mo weldment are available. The test results show a small additional shift in transition temperature for HT-9 base metal irradiated at 390 0 C and 450 0 C as the fluence was raised to 6 x 10 22 n/cm 2 . At higher irradiation temperatures, however, the shift in transition temperature is less conclusive. Further reduction in USE was observed at higher fluence for all the irradiation temperatures. There is no apparent fluence effect for 9Cr-1Mo base metal at all the irradiation temperatures studied. Contrary to the previous finding on HT-9 base metal and weldment, the 9Cr-1Mo weldment shows a higher transition temperature ( + 60 0 C) and a higher USE ( + 100%) as compared to the 9Cr-1MO base metal for the same irradiation conditions. 6 references, 7 figures, 7 tables

  14. Infinite number of solvable generalizations of XY-chain, with cluster state, and with central charge c=m/2

    Directory of Open Access Journals (Sweden)

    Kazuhiko Minami

    2017-12-01

    Full Text Available An infinite number of spin chains are solved and it is derived that the ground-state phase transitions belong to the universality classes with central charge c=m/2, where m is an integer. The models are diagonalized by automatically obtained transformations, many of which are different from the Jordan–Wigner transformation. The free energies, correlation functions, string order parameters, exponents, central charges, and the phase diagram are obtained. Most of the examples consist of the stabilizers of the cluster state. A unified structure of the one-dimensional XY and cluster-type spin chains is revealed, and other series of solvable models can be obtained through this formula.

  15. Resonantly-enhanced, four-photon ionization of krypton at laser intensities exceeding 1013 W/cm2

    International Nuclear Information System (INIS)

    Perry, M.D.; Landen, O.L.; Campbell, E.M.

    1987-12-01

    The yield of singly- and multiply- charged ions of krypton and xenon is presented as a function of laser intensity and frequency. The measurements were performed using the second harmonic output of a well-characterized, tunable picosecond dye laser in the range 285 to 310 nm at laser intensities from 1 x 10 12 to 10 14 W/cm 2 . Enhancement of the Kr + yield by two orders of magnitude by three-photon resonant, four-photon ionization is observed in the vicinity of the 4d'[5/2] 3 and the 4d[3/2] 1 intermediate states. A model incorporating line shifts and widths scaling linearly with intensity is in good agreement with the experimental results

  16. Design and fabrication of prototype 6×6 cm2 microchannel plate photodetector with bialkali photocathode for fast timing applications

    International Nuclear Information System (INIS)

    Xie, Junqi; Byrum, Karen; Demarteau, Marcel; Gregar, Joseph; May, Edward; Virgo, Mathew; Wagner, Robert; Walters, Dean; Wang, Jingbo; Xia, Lei; Zhao, Huyue

    2015-01-01

    Planar microchannel plate-based photodetectors with a bialkali photocathode are able to achieve photon detection with very good time and position resolution. A 6×6 cm 2 photodetector production facility was designed and built at Argonne National Laboratory. Small form-factor MCP-based photodetectors completely constructed out of glass were designed and prototypes were successfully fabricated. Knudsen effusion cells were incorporated in the photocathode growth chamber to achieve uniform and high quantum efficiency photocathodes. The thin film uniformity was simulated and measured for an antimony film deposition, showing uniformity of better than 10%. Several prototype devices with bialkali photocathodes have been fabricated with the described system and their characteristics were evaluated in the large signal (multi-PE) limit. A typical prototype device exhibits time-of-flight resolution of ~27 psec and differential time resolution of ~9 psec, corresponding to spatial resolution of ~0.65 mm

  17. Pricing in M/M/1 queues when cost of waiting in queue differs from cost of waiting in service

    Directory of Open Access Journals (Sweden)

    Görkem Sarıyer

    2016-11-01

    Full Text Available Service providers can adjust the entrance price to the state of the demand in real life service systems where the customers' decision to receive the service, is based on this price, state of demand and other system parameters. We analyzed service provider's short and long term pricing problems in unobservable M/M/1 queues having the rational customers, where, for customers, the unit cost of waiting in the queue is higher than unit cost of waiting in the service. We showed that waiting in the queue has a clear negative effect on customers’ utilities, hence the service provider's price values. We also showed that, in the short term, monopolistic pricing is optimal for congested systems with high server utilization levels, whereas in the long term, market capturing pricing is more profitable.

  18. Performance of an M/M/1 Retrial Queue with Working Vacation Interruption and Classical Retrial Policy

    Directory of Open Access Journals (Sweden)

    Tao Li

    2016-01-01

    Full Text Available An M/M/1 retrial queue with working vacation interruption is considered. Upon the arrival of a customer, if the server is busy, it would join the orbit of infinite size. The customers in the orbit will try for service one by one when the server is idle under the classical retrial policy with retrial rate nα, where n is the size of the orbit. During a working vacation period, if there are customers in the system at a service completion instant, the vacation will be interrupted. Under the stable condition, the probability generating functions of the number of customers in the orbit are obtained. Various system performance measures are also developed. Finally, some numerical examples and cost optimization analysis are presented.

  19. [A case of MM1+2 Creutzfeldt-Jakob disease with a longitudinal study of EEG and MRI].

    Science.gov (United States)

    Katsube, Mizuho; Shiota, Yuri; Harada, Takayuki; Shibata, Hiroshi; Nagai, Atsushi

    2013-11-01

    We report a case of definite MM1 + 2 sporadic Creutzfeldt-Jakob disease (sCJD). A 66-year-old woman was admitted to our hospital with memory disturbance and disorientation for three months. On admission she presented a progressive cognitive insufficiency. Electroencephalography (EEG) revealed a frontal intermittent rhythmical delta activity (FIRDA) and the brain magnetic resonance imaging (MRI) showed high signal intensities in cerebral cortex on diffusion weighted images (DWI). After four months from the onset, she reached the akinetic mutism state followed by myoclonus. Follow up examination revealed that periodic synchronous discharge (PSD) was found in EEG, and DWI revealed enlargement of high signal intensity lesions in cerebral cortex. At seven months from the onset, PSD and high signal intensities of cortex became unclear with disappearance of myoclonus, and brain white matter lesions were evident on MRI. Serial studies of EEG and MRI revealed that PSD generalized from frontal lobe dominant pattern, while high signal intensity lesions of cortex diffusely increased on DWI. At ten months from the onset patient died. Pathological examination in brain showed moderate and diffuse neuronal cell loss and gliosis in cerebral cortex corresponding with DWI changes. The genotype at codon 129 of the prion protein (PrP) was homozygous methionine (MM) and the type of protease-resistant PrP (PrPres) was the mixed type of 1 and 2 in Western blot analysis. It has been rare to analyze the changes of EEG and MRI in the entire stage and to investigate pathological finding in the case of sCJD-MM1 + 2. A longitudinal examination of EEG and MRI is useful for early diagnosis of CJD. Also we could correlate these findings with clinical and histopathological phenotype.

  20. Spectral reflectance "deconstruction" of the Murchison CM2 carbonaceous chondrite and implications for spectroscopic investigations of dark asteroids

    Science.gov (United States)

    Cloutis, Edward A.; Pietrasz, Valerie B.; Kiddell, Cain; Izawa, Matthew R. M.; Vernazza, Pierre; Burbine, Thomas H.; DeMeo, Francesca; Tait, Kimberly T.; Bell, James F.; Mann, Paul; Applin, Daniel M.; Reddy, Vishnu

    2018-05-01

    Carbonaceous chondrites (CCs) are important materials for understanding the early evolution of the solar system and delivery of volatiles and organic material to the early Earth. Presumed CC-like asteroids are also the targets of two current sample return missions: OSIRIS-REx to asteroid Bennu and Hayabusa-2 to asteroid Ryugu, and the Dawn orbital mission at asteroid Ceres. To improve our ability to identify and characterize CM2 CC-type parent bodies, we have examined how factors such as particle size, particle packing, and viewing geometry affect reflectance spectra of the Murchison CM2 CC. The derived relationships have implications for disc-resolved examinations of dark asteroids and sampleability. It has been found that reflectance spectra of slabs are more blue-sloped (reflectance decreasing toward longer wavelengths as measured by the 1.8/0.6 μm reflectance ratio), and generally darker, than powdered sample spectra. Decreasing the maximum grain size of a powdered sample results in progressively brighter and more red-sloped spectra. Decreasing the average grain size of a powdered sample results in a decrease in diagnostic absorption band depths, and redder and brighter spectra. Decreasing porosity of powders and variations in surface texture result in spectral changes that may be different as a function of viewing geometry. Increasing thickness of loose dust on a denser powdered substrate leads to a decrease in absorption band depths. Changes in viewing geometry lead to different changes in spectral metrics depending on whether the spectra are acquired in backscatter or forward-scatter geometries. In backscattered geometry, increasing phase angle leads to an initial increase and then decrease in spectral slope, and a general decrease in visible region reflectance and absorption band depths, and frequent decreases in absorption band minima positions. In forward scattering geometry, increasing phase angle leads to small non-systematic changes in spectral slope

  1. Defect-Free Large-Area (25 cm2 Light Absorbing Perovskite Thin Films Made by Spray Coating

    Directory of Open Access Journals (Sweden)

    Mehran Habibi

    2017-03-01

    Full Text Available In this work, we report on reproducible fabrication of defect-free large-area mixed halide perovskite (CH3NH3PbI3−xClx thin films by scalable spray coating with the area of 25 cm2. This is essential for the commercialization of the perovskite solar cell technology. Using an automated spray coater, the film thickness and roughness were optimized by controlling the solution concentration and substrate temperature. For the first time, the surface tension, contact angle, and viscosity of mixed halide perovskite dissolved in dimethylformamide (DMF are reported as a function of the solution concentration. A low perovskite solution concentration of 10% was selected as an acceptable value to avoid crystallization dewetting. The determined optimum substrate temperature of 150 °C, followed by annealing at 100 °C render the highest perovskite precursor conversion, as well as the highest possible droplet spreading, desired to achieve a continuous thin film. The number of spray passes was also tuned to achieve a fully-covered film, for the condition of the spray nozzle used in this work. This work demonstrates that applying the optimum substrate temperature decreases the standard deviation of the film thickness and roughness, leading to an increase in the quality and reproducibility of the large-area spray-on films. The optimum perovskite solution concentration and the substrate temperature are universally applicable to other spray coating systems.

  2. Pressurized thermal shock. CNA-I behavior when a hot leg breaks of 50 cm2 is produced

    International Nuclear Information System (INIS)

    Rosso, Ricardo D.; Ventura, Mirta A.

    2002-01-01

    Pressurized thermal shock (PTS) phenomena in the CNA-I pressurize heavy water reactor is analyzed in this paper. The initiating event is a hypothetical 50 cm 2 break of the line connecting the pressurizer and the primary system. The calculation procedure for obtaining the local thermal-hydraulic parameters in the reactor pressure vessel downcomer is described firstly. Results obtained lead to conclusions in different subjects. The first conclusion is that a simple tool of easy application is available to analyze PTS phenomena in cases of breaks in the primary system in cold and hot legs. This methodology is fully independent of the methodology utilized by the Utility. Another important conclusion comes from the analysis of the temperature evolution of the fluid below the cold leg level in the RPV downcomer, as a function of the T HPI temperature of the TJ system injected water from. It is also concluded that the results obtained with the methodology adopted agree with the ones obtained with the methodologies validated against experiments in the UPTF facility. It is possible to observe that when T HPI increase, the conditions suitable for PTS occurrence in a LOCA accident tend to diminish. The maximum value to the T HPI may be fixed from the maximum temperature allowed to preserve the structural integrity of the fuel cladding. (author)

  3. Correlated silicon and titanium isotopic compositions of presolar SiC grains from the Murchison CM2 chondrite

    Science.gov (United States)

    Gyngard, Frank; Amari, Sachiko; Zinner, Ernst; Marhas, Kuljeet Kaur

    2018-01-01

    We report correlated Si, and Ti isotopic compositions and elemental concentrations of 238 presolar SiC grains from the Murchison CM2 meteorite. Combined with measurements of the C and N isotopic compositions of these 238 grains, 220 were determined to be of type mainstream, 10 type AB, 4 type Y and 4 type Z. SiC grains of diameter ≳2.5 μm, to ensure enough material to attempt Ti measurements, were randomly chosen without any other prejudice. The Ti isotopic compositions of the majority of the grains are characterized by enrichments in 46Ti, 47Ti, 49Ti, and 50Ti relative to 48Ti, and show linear isotopic correlations indicative of galactic chemical evolution and neutron capture of the grains parent stars. The variability in the observed Ti signal as a function of depth in most of the grains indicates the presence of distinct subgrains, likely TiC that have been previously observed in TEM studies. Vandium-51 concentrations correlate with those of Ti, indicating V substitutes for Ti in the TiC matrix in many of the grains. No isotopic anomalies in 52Cr/53Cr ratios were observed, and Cr concentrations did not correlate with those of either Ti or V.

  4. Development of a computational model applied to a unitary 144 CM2 proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Robalinho, Eric

    2009-01-01

    This work presents the development of a numerical computer model and methodology to study and design polymeric exchange membrane fuel cell - PEM. For the validation of experimental results, a sequence of routines, appropriate to fit the data obtained in the laboratory, was described. At the computational implementation it was created a new strategy of coupling two 3-dimensional models to satisfy the requirements of the comprehensive model of the fuel cell, including its various geometries and materials, as well as the various physical and chemical processes simulated. To effective assessment of the real cell analogy with numerical model, numerical studies were carried out. Comparisons with values obtained in the literature, characterization of variables through laboratory experiments and estimates from models already tested in the literature were also performed. Regarding the experimental part, a prototype of a fuel cell unit of 144 cm 2 of geometric area was designed, produced and operated at laboratory with the purpose of validating the numerical computer model proposed, with positive results. The results of simulations for the 2D and 3D geometries proposed are presented in the form of polarization curves, highlighting the catalytic layer model based on the geometry of agglomerates. Parametric and sensitivity studies are presented to illustrate the change in performance of the fuel cell studied. The final model is robust and useful as a tool for design and optimization of PEM type fuel cells in a wide range of operating conditions. (author)

  5. Achieving high carrier mobility exceeding 70 cm2/Vs in amorphous zinc tin oxide thin-film transistors

    Science.gov (United States)

    Kim, Sang Tae; Shin, Yeonwoo; Yun, Pil Sang; Bae, Jong Uk; Chung, In Jae; Jeong, Jae Kyeong

    2017-09-01

    This paper proposes a new defect engineering concept for low-cost In- and Ga-free zinc tin oxide (ZTO) thin-film transistors (TFTs). This concept is comprised of capping ZTO films with tantalum (Ta) and a subsequent modest thermal annealing treatment at 200 °C. The Ta-capped ZTO TFTs exhibited a remarkably high carrier mobility of 70.8 cm2/Vs, low subthreshold gate swing of 0.18 V/decade, threshold voltage of -1.3 V, and excellent ION/OFF ratio of 2 × 108. The improvement (> two-fold) in the carrier mobility compared to the uncapped ZTO TFT can be attributed to the effective reduction of the number of adverse tailing trap states, such as hydroxyl groups or oxygen interstitial defects, which stems from the scavenging effect of the Ta capping layer on the ZTO channel layer. Furthermore, the Ta-capped ZTO TFTs showed excellent positive and negative gate bias stress stabilities. [Figure not available: see fulltext.

  6. Adherence problem for carbon films of up to 0.5 mg/cm2 on vacuum-deposited thick ferromagnetic Gd targets

    International Nuclear Information System (INIS)

    Maier-Komor, P.; Kruecken, R.; Speidel, K.-H.; Kenn, O.

    2004-01-01

    For high precision measurements of magnetic moments and reduced transition probabilities by the combined technique of projectile Coulomb excitation in inverse kinematics and transient magnetic fields sandwich targets of carbon and gadolinium were required. First preparations revealed a lack of adhesion between the Gd film and the vacuum-deposited C layer. Either the adhesion was generally poor or good results could not be reproduced. Now on a 4 mg/cm 2 Gd target 0.5 mg/cm 2 of nat C should be deposited. The Gd was deposited on 1-1.6 mg/cm 2 Ta backings and Cu films of 3.5-7 mg/cm 2 were deposited on the reverse side of the Ta backings. The adhesive properties of evaporated carbon on ferromagnetic gadolinium were investigated. For this either substrate cooling or the deposition of a 5 μg/cm 2 Ti film as adhesion agent were applied

  7. Bidirectional multi-optical line terminals incorporated converged WSN-PON network using M/M/1 queuing

    Science.gov (United States)

    Kumar, Love; Sharma, Vishal; Singh, Amarpal

    2017-12-01

    Wireless Sensor Networks (WSNs) have an assortment of application areas, for instance, civil, military, and video surveillance with restricted power resources and transmission link. To accommodate the massive traffic load in hefty sensor networks is another key issue. Subsequently, there is a necessity to backhaul the sensed information of such networks and prolong the transmission link to access the distinct receivers. Passive Optical Network (PON), a next-generation access technology, comes out as a suitable candidate for the convergence of the sensed data to the core system. The earlier demonstrated work with single-OLT-PON introduces an overloaded buffer akin to video surveillance scenarios. In this paper, to combine the bandwidth potential of PONs with the mobility capability of WSNs, the viability for the convergence of PONs and WSNs incorporating multi-optical line terminals is demonstrated to handle the overloaded OLTs. The existing M/M/1 queue theory with interleaving polling with adaptive cycle time as dynamic bandwidth algorithm is used to shun the probability of packets clash. Further, the proposed multi-sink WSN and multi-OLT PON converged structure is investigated in bidirectional mode analytically and through computer simulations. The observations establish the proposed structure competent to accommodate the colossal data traffic through less time consumption.

  8. Oxygen isotope systematics of chondrules in the Murchison CM2 chondrite and implications for the CO-CM relationship

    Science.gov (United States)

    Chaumard, Noël; Defouilloy, Céline; Kita, Noriko T.

    2018-05-01

    High-precision oxygen three-isotope measurements of olivine and pyroxene were performed on 29 chondrules in the Murchison CM2 chondrite by secondary ion mass spectrometry (SIMS). The oxygen isotope ratios of analyzed chondrules all plot very close to the primitive chondrule minerals (PCM) line. In each of 24 chondrules, the olivine and/or pyroxene grains analyzed show indistinguishable oxygen isotope ratios. Exceptions are minor occurrences of isotopically distinguished relict olivine grains, which were found in nine chondrules. The isotope homogeneity of these phenocrysts is consistent with a co-magmatic crystallization of olivine and pyroxene from the final chondrule melts and a significant oxygen isotope exchange between the ambient gas and the melts. Homogeneous type I chondrules with Mg#'s of 98.9-99.5 have host chondrule Δ17O values ranging from -6.0‰ to -4.1‰, with one exception (Δ17O: -1.2‰; Mg#: 99.6). Homogeneous chondrules with Mg#'s poor H2O ice (∼0.3-0.4× the CI dust; Δ17O > 0‰) and at dust enrichments of ∼300-2000×. Regarding the Mg# and oxygen isotope ratios, the chondrule populations sampled by CM and CO chondrites are similar and indistinguishable. The similarity of these 16O-rich components in CO and CM chondrites is also supported by the common Fe/Mn ratio of olivine in type II chondrules. Although they accreted similar high-temperature silicates, CO chondrites are anhydrous compared to CM chondrites, suggesting they derived from different parent bodies formed inside and outside the snow line, respectively. If chondrules in CO and CM chondrites formed at the same disk locations but the CM parent body accreted later than the CO parent body, the snow line might have crossed the common chondrule-forming region towards the Sun between the time of the CO and CM parent bodies accretion.

  9. Red light photodynamic therapy for actinic keratosis using 37 J/cm2 : Fractionated irradiation with 12.3 mW/cm2 after 30 minutes incubation time compared to standard continuous irradiation with 75 mW/cm2 after 3 hours incubation time using a mathematical modeling.

    Science.gov (United States)

    Vignion-Dewalle, Anne-Sophie; Baert, Gregory; Devos, Laura; Thecua, Elise; Vicentini, Claire; Mortier, Laurent; Mordon, Serge

    2017-09-01

    Photodynamic therapy (PDT) is an emerging treatment modality for various diseases, especially for dermatological conditions. Although, the standard PDT protocol for the treatment of actinic keratoses in Europe has shown to be effective, treatment-associated pain is often observed in patients. Different modifications to this protocol attempted to decrease pain have been investigated. The decrease in fluence rate seems to be a promising solution. Moreover, it has been suggested that light fractionation significantly increases the efficacy of PDT. Based on a flexible light-emitting textile, the FLEXITHERALIGHT device specifically provides a fractionated illumination at a fluence rate more than six times lower than that of the standard protocol. In a recently completed clinical trial of PDT for the treatment of actinic keratosis, the non-inferiority of a protocol involving illumination with the FLEXITHERALIGHT device after a short incubation time and referred to as the FLEXITHERALIGHT protocol has been assessed compared to the standard protocol. In this paper, we propose a comparison of the two above mentioned 635 nm red light protocols with 37 J/cm 2 in the PDT treatment of actinic keratosis: the standard protocol and the FLEXITHERALIGHT one through a mathematical modeling. This mathematical modeling, which slightly differs from the one we have already published, enables the local damage induced by the therapy to be estimated. The comparison performed in terms of the local damage induced by the therapy demonstrates that the FLEXITHERALIGHT protocol with lower fluence rate, light fractionation and shorter incubation time is somewhat less efficient than the standard protocol. Nevertheless, from the clinical trial results, the FLEXITHERALIGHT protocol results in non-inferior response rates compared to the standard protocol. This finding raises the question of whether the PDT local damage achieved by the FLEXITHERALIGHT protocol (respectively, the standard protocol

  10. Ga2O3 Schottky rectifiers with 1 ampere forward current, 650 V reverse breakdown and 26.5 MW.cm-2 figure-of-merit

    Science.gov (United States)

    Yang, Jiancheng; Ren, F.; Tadjer, Marko; Pearton, S. J.; Kuramata, A.

    2018-05-01

    A key goal for Ga2O3 rectifiers is to achieve high forward currents and high reverse breakdown voltages. Field-plated β-Ga2O3 Schottky rectifiers with area 0.01 cm2, fabricated on 10 μm thick, lightly-doped drift regions (1.33 x 1016 cm-3) on heavily-doped (3.6 x 1018 cm-3) substrates, exhibited forward current density of 100A.cm-2 at 2.1 V, with absolute current of 1 A at this voltage and a reverse breakdown voltage (VB) of 650V. The on-resistance (RON) was 1.58 x 10-2 Ω.cm2, producing a figure of merit (VB2/RON) of 26.5 MW.cm-2. The Schottky barrier height of the Ni was 1.04 eV, with an ideality factor of 1.02. The on/off ratio was in the range 3.3 x 106 - 5.7 x 109 for reverse biases between 5 and 100V. The reverse recovery time was ˜30 ns for switching from +2V to -5V. The results show the capability of β-Ga2O3 rectifiers to achieve exceptional performance in both forward and reverse bias conditions.

  11. Patch test concentrations (doses in mg/cm(2) ) for the 12 non-mix fragrance substances regulated by European legislation

    DEFF Research Database (Denmark)

    Bruze, Magnus; Svedman, Cecilia; Andersen, Klaus Ejner

    2012-01-01

    Background. According to EU legislation, 26 fragrance substance allergens must be labelled on cosmetic products. For 12 of them, the optimal patch test concentration/dose has not been evaluated. Objectives. To establish the optimal patch test doses in mg/cm(2) for the 12 fragrance substances......, it is recommended that half of the maximum patch test dose (mg/cm(2) ) be used for aimed and screening patch testing....... that are not included in fragrance mix I or II in the European baseline patch test series. Materials and Methods. Patch testing with the 12 fragrance substances was performed in a stepwise manner encompassing up to five rounds in at least 100 dermatitis patients for each round. Before patch testing, an individual...

  12. Electron photon spectra at atmospheric depths 260 and 400 gm/cm2 derived from the Goddard primary proton spectrum using Fermilab data and usual cascade theory

    International Nuclear Information System (INIS)

    Bhattacharyya, D.P.; Gautam, V.P.

    1982-01-01

    The integral electron photon spectra of cosmic rays at airplane altitude and Lenin Peak (altitudes 260 and 400 g-cm -2 air) have been estimated from the primary proton spectrum of Goddard Space Flight Group using Fermilab data of pp→π +- +X and conventional cascade theory. The derived electron-photon spectra fits well the experimental data of Ohta et al. (1975) and Cherdyntseva and Nikol'skii (1976) for energies above 4 TeV

  13. Gain and time resolution of 45 μm thin Low Gain Avalanche Detectors before and after irradiation up to a fluence of 1015 neq/cm2

    CERN Document Server

    Lange, J; Cavallaro, E; Chytka, L; Davis, P.M; Flores, D; Förster, F; Grinstein, S; Hidalgo, S; Komarek, T; Kramberger, G; Mandić, I; Merlos, A; Nozka, L; Pellegrini, G; Quirion, D; Sykora, T; Physics

    2018-01-01

    The gain showed the expected decrease at a fixed voltage for a lower initial implantation dose, as well as for a higher fluence due to effective acceptor removal in the multiplication layer. Time resolutions below 30 ps were obtained at the highest applied voltages for both implantation doses before irradiation. Also after an intermediate fluence of 3 × 1014 neq/cm2, similar values were measured since a higher applicable reverse bias voltage could recover most of the pre-irradiation gain...

  14. Asymmetrical squaraines for high-performance small-molecule organic solar cells with a short circuit current of over 12 mA cm(-2).

    Science.gov (United States)

    Chen, Yao; Zhu, Youqin; Yang, Daobin; Luo, Qian; Yang, Lin; Huang, Yan; Zhao, Suling; Lu, Zhiyun

    2015-04-11

    An asymmetrical squaraine dye (Py-3) with its two electron-donating aryl groups directly linked to the electron-withdrawing squaric acid core possesses an ideal bandgap of 1.33 eV, together with an intense and broad absorption band in the range 550-950 nm. Hence, the resulting solution-processed solar cells display an impressive Jsc of 12.03 mA cm(-2) and a PCE of 4.35%.

  15. Feasibility Study for Implementing Magnetic Suspension in the Glenn Research Center 225 cm2 Supersonic Wind Tunnel for Testing the Dynamic Stability of Blunt Bodies

    Science.gov (United States)

    Sevier, Abigail; Davis, David O.; Schoenenberger, Mark; Barnhart, Paul

    2016-01-01

    The implementation of a magnetic suspension system in the NASA Glenn Research Center (GRC) 225 cm2 Supersonic Wind Tunnel would be a powerful test technique that could accurately determine the dynamic stability of blunt body entry vehicles with no sting interference. This paper explores initial design challenges to be evaluated before implementation, including defining the lowest possible operating dynamic pressure and corresponding model size, developing a compatible video analysis technique, and incorporating a retractable initial support sting.

  16. Gain and time resolution of 45 μm thin Low Gain Avalanche Detectors before and after irradiation up to a fluence of 1015 neq/cm2

    International Nuclear Information System (INIS)

    Lange, J.; Cavallaro, E.; Förster, F.; Grinstein, S.; Carulla, M.; Flores, D.; Hidalgo, S.; Merlos, A.; Pellegrini, G.; Quirion, D.; Chytka, L.; Komarek, T.; Nozka, L.; Davis, P.M.; Kramberger, G.; Mandić, I.; Sykora, T.

    2017-01-01

    Low Gain Avalanche Detectors (LGADs) are silicon sensors with a built-in charge multiplication layer providing a gain of typically 10 to 50. Due to the combination of high signal-to-noise ratio and short rise time, thin LGADs provide good time resolutions. LGADs with an active thickness of about 45 μm were produced at CNM Barcelona. Their gains and time resolutions were studied in beam tests for two different multiplication layer implantation doses, as well as before and after irradiation with neutrons up to 10 15 n eq /cm 2 . The gain showed the expected decrease at a fixed voltage for a lower initial implantation dose, as well as for a higher fluence due to effective acceptor removal in the multiplication layer. Time resolutions below 30 ps were obtained at the highest applied voltages for both implantation doses before irradiation. Also after an intermediate fluence of 3×10 14 n eq /cm 2 , similar values were measured since a higher applicable reverse bias voltage could recover most of the pre-irradiation gain. At 10 15 n eq /cm 2 , the time resolution at the maximum applicable voltage of 620 V during the beam test was measured to be 57 ps since the voltage stability was not good enough to compensate for the gain layer loss. The time resolutions were found to follow approximately a universal function of gain for all implantation doses and fluences.

  17. Heavy metals detection using biosensor cells of a novel marine luminescent bacterium Vibrio sp. MM1 isolated from the Caspian Sea.

    Science.gov (United States)

    Mohseni, Mojtaba; Abbaszadeh, Jaber; Maghool, Shima-Sadat; Chaichi, Mohammad-Javad

    2018-02-01

    Monitoring and assessing toxic materials which are being released into the environment along with wastewater is a growing concern in many industries. The current research describes a highly sensitive and rapid method for the detection of toxic concentrations of heavy metals in aquatic environments. Water samples were collected from southern coasts of the Caspian Sea followed by screening of luminescent bacteria. Phylogenetic analysis, including gene sequence of 16S rRNA, and biochemical tests were performed for identification of the isolate. Luminescence activity was tested and measured after treatment of the isolate with different concentrations of heavy metals and reported as EC 50 value for each metal. A luminous, gram negative bacterium with the shape of a curved rod was isolated from the Caspian Sea. Biochemical tests and 16S rRNA gene sequence analysis indicated that the isolate MM1 had more than 99% similarity to Vibrio campbellii. The novel isolate is able to emit high levels of light. Bioluminescence inhibitory assay showed that the Vibrio sp. MM1 had the highest sensitivity to zinc and the lowest sensitivity to cadmium; EC 50 values were 0.97mgl -1 and 14.54mgl -1 , respectively. The current research shows that even low concentrations of heavy metals can cause a detectable decline in luminescence activity of the novel bacterium Vibrio sp. MM1; hence, it makes a good choice for commercial kits for the purpose of monitoring toxic materials. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Effects of fast-neutron damage from 0 to 42 x 1021 neutrons/CM2 on the physical properties of near-isotropic grades of graphite

    International Nuclear Information System (INIS)

    Cook, W.H.; Kennedy, C.R.; Eatherly, W.P.

    1975-01-01

    The characterization of property changes in various grades of near-isotropic, ''binderless'' grades of graphite as functions of fluence accumulated at 715 0 C from 0 to 42 x 10 21 neutrons/cm 2 (E greater than 50 keV) was made. Generally, the average coefficients of thermal expansion (CTE) from 20 to 600 0 C and the room-temperature values for strengths, fracture strains, Young's moduli, shear moduli, and calculated figures of merit (FOM) for resistance to thermal shock all ultimately decreased with fluence. (U.S.)

  19. Measurements of the ultrasonic attenuation and velocity variation in neutron irradiated quartz for an intermediate dose of 2.6x1019 n/cm2

    International Nuclear Information System (INIS)

    Keppens, V.; Laermans, C.

    1992-01-01

    Ultrasonic measurements in neutron-irradiated quartz are carried out for an intermediate dose of 2.6x10 19 n/cm 2 . The variation of the velocity of sound has been measured and previous attenuation measurements are extended to temperatures below 1.2 K. The TS-parameters anti P and γ 1 are calculated from numerical fittings to the tunneling model. The obtained values continue the tendency of previous measurements for lower neutron doses, where a linear increase of anti P with the dose was found. This behaviour, however, is not followed by a higher dose, situated near the ''threshold regime''. (orig.)

  20. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm 2/Vs

    KAUST Repository

    Smith, Jeremy N.

    2012-04-10

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm 2/Vs, current on/off ratio ≥10 6 and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Solution-processed small molecule-polymer blend organic thin-film transistors with hole mobility greater than 5 cm 2/Vs

    KAUST Repository

    Smith, Jeremy N.; Zhang, Weimin; Sougrat, Rachid; Zhao, Kui; Li, Ruipeng; Cha, Dong Kyu; Amassian, Aram; Heeney, Martin J.; McCulloch, Iain A.; Anthopoulos, Thomas D.

    2012-01-01

    Using phase-separated organic semiconducting blends containing a small molecule, as the hole transporting material, and a conjugated amorphous polymer, as the binder material, we demonstrate solution-processed organic thin-film transistors with superior performance characteristics that include; hole mobility >5 cm 2/Vs, current on/off ratio ≥10 6 and narrow transistor parameter spread. These exceptional characteristics are attributed to the electronic properties of the binder polymer and the advantageous nanomorphology of the blend film. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Radiative transfer modelling of W33A MM1: 3-D structure and dynamics of a complex massive star forming region

    Science.gov (United States)

    Izquierdo, Andrés F.; Galván-Madrid, Roberto; Maud, Luke T.; Hoare, Melvin G.; Johnston, Katharine G.; Keto, Eric R.; Zhang, Qizhou; de Wit, Willem-Jan

    2018-05-01

    We present a composite model and radiative transfer simulations of the massive star forming core W33A MM1. The model was tailored to reproduce the complex features observed with ALMA at ≈0.2 arcsec resolution in CH3CN and dust emission. The MM1 core is fragmented into six compact sources coexisting within ˜1000 au. In our models, three of these compact sources are better represented as disc-envelope systems around a central (proto)star, two as envelopes with a central object, and one as a pure envelope. The model of the most prominent object (Main) contains the most massive (proto)star (M⋆ ≈ 7 M⊙) and disc+envelope (Mgas ≈ 0.4 M⊙), and is the most luminous (LMain ˜ 104 L⊙). The model discs are small (a few hundred au) for all sources. The composite model shows that the elongated spiral-like feature converging to the MM1 core can be convincingly interpreted as a filamentary accretion flow that feeds the rising stellar system. The kinematics of this filament is reproduced by a parabolic trajectory with focus at the center of mass of the region. Radial collapse and fragmentation within this filament, as well as smaller filamentary flows between pairs of sources are proposed to exist. Our modelling supports an interpretation where what was once considered as a single massive star with a ˜103 au disc and envelope, is instead a forming stellar association which appears to be virialized and to form several low-mass stars per high-mass object.

  3. PrP mRNA and protein expression in brain and PrP(c) in CSF in Creutzfeldt-Jakob disease MM1 and VV2.

    Science.gov (United States)

    Llorens, Franc; Ansoleaga, Belén; Garcia-Esparcia, Paula; Zafar, Saima; Grau-Rivera, Oriol; López-González, Irene; Blanco, Rosi; Carmona, Margarita; Yagüe, Jordi; Nos, Carlos; Del Río, José Antonio; Gelpí, Ellen; Zerr, Inga; Ferrer, Isidre

    2013-01-01

    Creutzfeldt-Jakob disease (CJD) is a heterogenic neurodegenerative disorder associated with abnormal post-translational processing of cellular prion protein (PrP(c)). CJD displays distinctive clinical and pathological features which correlate with the genotype at the codon 129 (methionine or valine: M or V respectively) in the prion protein gene and with size of the protease-resistant core of the abnormal prion protein PrP(sc) (type 1: 20/21 kDa and type 2: 19 kDa). MM1 and VV2 are the most common sporadic CJD (sCJD) subtypes. PrP mRNA expression levels in the frontal cortex and cerebellum are reduced in sCJD in a form subtype-dependent. Total PrP protein levels and PrP(sc) levels in the frontal cortex and cerebellum accumulate differentially in sCJD MM1 and sCJD VV2 with no relation between PrP(sc) deposition and spongiform degeneration and neuron loss, but with microgliosis, and IL6 and TNF-α response. In the CSF, reduced PrP(c), the only form present in this compartment, occurs in sCJD MM1 and VV2. PrP mRNA expression is also reduced in the frontal cortex in advanced stages of Alzheimer disease, Lewy body disease, progressive supranuclear palsy, and frontotemporal lobe degeneration, but PrP(c) levels in brain varies from one disease to another. Reduced PrP(c) levels in CSF correlate with PrP mRNA expression in brain, which in turn reflects severity of degeneration in sCJD.

  4. Current density and catalyst-coated membrane resistance distribution of hydro-formed metallic bipolar plate fuel cell short stack with 250 cm2 active area

    Science.gov (United States)

    Haase, S.; Moser, M.; Hirschfeld, J. A.; Jozwiak, K.

    2016-01-01

    An automotive fuel cell with an active area of 250 cm2 is investigated in a 4-cell short stack with a current and temperature distribution device next to the bipolar plate with 560 current and 140 temperature segments. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this current scan shunt module. The applied fuel cell consists of bipolar plates constructed of 75-μm-thick, welded stainless-steel foils and a graphitic coating. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this module with a 6% deviation in in-plane conductivity. The current density distribution is evaluated up to 2.4 A cm-2. The entire cell's investigated volumetric power density is 4.7 kW l-1, and its gravimetric power density is 4.3 kW kg-1 at an average cell voltage of 0.5 V. The current density distribution is determined without influencing the operating cell. In addition, the current density distribution in the catalyst-coated membrane and its effective resistivity distribution with a finite volume discretisation of Ohm's law are evaluated. The deviation between the current density distributions in the catalyst-coated membrane and the bipolar plate is determined.

  5. Patch test concentrations (doses in mg/cm2 ) for the 12 non-mix fragrance substances regulated by European legislation.

    Science.gov (United States)

    Bruze, Magnus; Svedman, Cecilia; Andersen, Klaus Ejner; Bruynzeel, Derk; Goossens, An; Johansen, Jeanne Duus; Matura, Mihaly; Orton, David; Vigan, Martine

    2012-03-01

    According to EU legislation, 26 fragrance substance allergens must be labelled on cosmetic products. For 12 of them, the optimal patch test concentration/dose has not been evaluated. To establish the optimal patch test doses in mg/cm2 for the 12 fragrance substances that are not included in fragrance mix I or II in the European baseline patch test series. Patch testing with the 12 fragrance substances was performed in a stepwise manner encompassing up to five rounds in at least 100 dermatitis patients for each round. Before patch testing, an individual maximum concentration/dose was determined for each fragrance substance. The predetermined maximum patch test concentrations/doses could be tested for all 12 fragrance substances, with no observable adverse reactions being noted. For each fragrance substance investigated, it is recommended that half of the maximum patch test dose (mg/cm2) be used for aimed and screening patch testing. © 2012 John Wiley & Sons A/S.

  6. The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm2

    Directory of Open Access Journals (Sweden)

    Lin-Yue Liu

    2017-10-01

    Full Text Available Silicon carbide (SiC detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm2 were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

  7. X-ray detection with Micromegas with background levels below 10$^{-6}$ keV$^{-1}$cm$^{-2}$s$^{-1}$

    CERN Document Server

    Aune, S; Calvet, D.; Dafni, T.; Diago, A.; Druillole, F.; Fanourakis, G.; Ferrer-Ribas, E.; Galán, J.; García, J.A.; Gardikiotis, A.; Garza, J.G.; Geralis, T.; Giomataris, I.; Gómez, H.; González-Díaz, D.; Herrera, D.C.; Iguaz, F.J.; Irastorza, I.G.; Jourde, D.; Luzón, G.; Mirallas, H.; Mols, J.P.; Papaevangelou, T.; Rodríguez, A.; Seguí, L.; Tomás, A.; Vafeiadis, T.; Yildiz, S.C.

    2013-01-01

    Micromegas detectors are an optimum technological choice for the detection of low energy x-rays. The low background techniques applied to these detectors yielded remarkable background reductions over the years, being the CAST experiment beneficiary of these developments. In this document we report on the latest upgrades towards further background reductions and better understanding of the detectors' response. The upgrades encompass the readout electronics, a new detector design and the implementation of a more efficient cosmic muon veto system. Background levels below 10$^{-6}$keV$^{-1}$cm$^{-2}$s$^{-1}$ have been obtained at sea level for the first time, demonstrating the feasibility of the expectations posed by IAXO, the next generation axion helioscope. Some results obtained with a set of measurements conducted in the x-ray beam of the CAST Detector Laboratory will be also presented and discussed.

  8. Mobility in excess of 106 cm2/V s in InAs quantum wells grown on lattice mismatched InP substrates

    Science.gov (United States)

    Hatke, A. T.; Wang, T.; Thomas, C.; Gardner, G. C.; Manfra, M. J.

    2017-10-01

    We investigate the transport properties of a two-dimensional electron gas residing in strained composite quantum wells of In0.75Ga0.25As/InAs/In0.75Ga0.25As cladded with In0.75Al0.25As barriers grown metamorphically on insulating InP substrates. By optimizing the widths of the In0.75Ga0.25As layers, the In0.75Al0.25As barrier, and the InAs quantum well, we demonstrate mobility in excess of 1 ×106 cm2/V s. Mobility vs. density data indicate that scattering is dominated by a residual three dimensional distribution of charged impurities. We extract the effective Rashba parameter and spin-orbit length for these composite quantum wells.

  9. 80 A/cm2 electron beams from metal targets irradiated by KrCl and XeCl excimer lasers

    Science.gov (United States)

    Beloglazov, A.; Martino, M.; Nassisi, V.

    1996-05-01

    Due to the growing demand for high-current and long-duration electron-beam devices, laser electron sources were investigated in our laboratory. Experiments on electron-beam generation and propagation from aluminium and copper targets illuminated by XeCl (308 nm) and KrCl (222 nm) excimer lasers, were carried out under plasma ignition due to laser irradiation. This plasma supplied a spontaneous accelerating electric field of about 370 kV/m without an external accelerating voltage. By applying the modified one-dimensional Poisson equation, we computed the expected current and we also estimated the plasma concentration during the accelerating process. At 40 kV of accelerating voltage, an output current pulse of about 80 A/cm2 was detected from an Al target irradiated by the shorter wavelength laser.

  10. Study of the response of a piezoceramic motor irradiated in a fast reactor up to a neutron fluence of 2.77E+17 n/cm2

    International Nuclear Information System (INIS)

    Pillon, Mario; Monti, Chiara; Mugnaini, Giampiero; Neri, Carlo; Rossi, Paolo; Carta, Mario; Fiorani, Orlando; Santagata, Alfonso

    2015-01-01

    Highlights: • Piezoceramic motors are compliant with magnetic field, temperature and vacuum. • We studied the response of a piezoceramic motor during the irradiation with neutrons. • The response was studied using 1 MeV neutrons up to a neutron fluence of 2.77E+17 n/cm 2 . • Neutron irradiation produces a shift of the optimal resonance frequency and a decrease of the motor speed. • The performance changes do not affect the proper operation of the motor. - Abstract: A piezoceramic motor has been identified as the potential apparatus for carrying out the rotation of the scanning head of a laser radar system used for viewing the first wall of the ITER vessel. This diagnostic is simply referred to as IVVS (In Vessel Viewing System). The choice fell on a piezoceramic motor due to the presence of strong magnetic fields (up 8 T) and of the high vacuum and temperature conditions. To be compliant with all the ITER environmental conditions it was necessary to qualify the piezo-motor under gamma and neutron irradiation. In this paper are described the procedures and tests that have been performed to verify the compatibility of the operation of the motor adopted in the presence of a fast neutron fluence which was gradually increased over time in order to reach a total value of 2.77 × 10 17 n/cm 2 . Such neutron fluence was obtained by irradiating the motor in a position close to the core of the fast nuclear reactor TAPIRO, in operation at the ENEA Casaccia Research Centre, Italy. The neutron spectrum in this position has been identified as representative of that found in the rest position of the IVVS head during ITER operation. The cumulative neutron fluence reached corresponds to that it is expected to be reached during the entire life of ITER for the IVVS in the rest position without any shield. This work describes the experimental results of this test; the methodology adopted to determine the total neutron fluence achieved and the methodology adopted for the

  11. Predicting the optimal process window for the coating of single-crystalline organic films with mobilities exceeding 7 cm2/Vs.

    Science.gov (United States)

    Janneck, Robby; Vercesi, Federico; Heremans, Paul; Genoe, Jan; Rolin, Cedric

    2016-09-01

    Organic thin film transistors (OTFTs) based on single crystalline thin films of organic semiconductors have seen considerable development in the recent years. The most successful method for the fabrication of single crystalline films are solution-based meniscus guided coating techniques such as dip-coating, solution shearing or zone casting. These upscalable methods enable rapid and efficient film formation without additional processing steps. The single-crystalline film quality is strongly dependent on solvent choice, substrate temperature and coating speed. So far, however, process optimization has been conducted by trial and error methods, involving, for example, the variation of coating speeds over several orders of magnitude. Through a systematic study of solvent phase change dynamics in the meniscus region, we develop a theoretical framework that links the optimal coating speed to the solvent choice and the substrate temperature. In this way, we can accurately predict an optimal processing window, enabling fast process optimization. Our approach is verified through systematic OTFT fabrication based on films grown with different semiconductors, solvents and substrate temperatures. The use of best predicted coating speeds delivers state of the art devices. In the case of C8BTBT, OTFTs show well-behaved characteristics with mobilities up to 7 cm2/Vs and onset voltages close to 0 V. Our approach also explains well optimal recipes published in the literature. This route considerably accelerates parameter screening for all meniscus guided coating techniques and unveils the physics of single crystalline film formation.

  12. Behavior to the fracture of an AISI 304 stainless steel sensitized in BWR reactor conditions (288 degrees Centigrade and 80 Kg/cm2)

    International Nuclear Information System (INIS)

    Hernandez C, R.; Diaz S, A.; Garcia R, R.; Aguilar T, A.; Gachuz M, M.; Arganis J, C.; Merino C, J.

    1999-01-01

    It is a knew fact that ductility of a lot of structural alloys can be deteriorated by the environment effect which are exposed, and that their consequent embrittlement can put in doubt the safety of their functioning; such is the case of austenitic stainless steels used in internal components of the BWR type reactors which not only is subjected to the effect combined of the aggressive environment which surround it (pressure, temperature, corrosion potential, conductivity medium, local state of efforts, etc.), but also to the action of present neutron radiation, manifesting microstructural changes which are reflected in the augmentation of its susceptibility to the intergranular cracking, phenomena generally known as IASCC ''Irradiation Assisted Stress Corrosion Cracking''. Once appeared the cracking in the material, the useful life of a component is limited by the rapidity to growth of these cracking, making necessary evaluations which can to predict its behavior, therefore the present work shows the preliminary results for determining the behavior to the fracture of an AISI 304 stainless steel sensitized, in a dynamic recirculation circuit which allows to simulate the operation conditions of a BWR reactor (288 Centigrade and 80 kg/cm 2 ). (Author)

  13. Operation of low-noise single-gap RPC modules exposed to ionisation rates up to 1 kHz/cm$^2$

    CERN Document Server

    Cwiok, M; Dominik, Wojciech; Górski, M; Królikowski, J; 10.1016/j.nima.2004.06.123

    2004-01-01

    Two single gap medium-size RPC modules, made of bakelite plates of very good mechanical quality of the surface and having initial volume resistivity of 1 multiplied by 10**1**0 omegacm, were tested in the Gamma Irradiation Facility at CERN at ionisation rates up to 1 kHz/cm **3. The internal surfaces facing the gas volume of one RPC module were cladded with a thin layer of linseed oil varnish for comparison of oiled and non-oiled RPC operation. The results refer to the gas mixture of C//2H//2F //4/isobutane (97:3) with SF//6 addition below 1%. The single gap modules exhibited full detection efficiency plateau for the high voltage range of about 1 kV at full intensity of gamma rays. Good timing characteristics allowed to reach 95% efficiency at fully opened irradiation source with time window of 20 ns. The intrinsic noise rate for a non-oiled and an oiled RPC gap was, respectively, below 5 and 1 Hz/cm**2 at full efficiency over 1 k V voltage range.

  14. Spectroscopic investigations of hard x-ray emission from 120 ps laser-produced plasmas at intensities near 1017 W cm-2

    International Nuclear Information System (INIS)

    Dunn, J.; Young, B.K.F.; Osterheld, A.L.; Foord, M.E.; Walling, R.S.; Stewart, R.E.; Faenov, A.Y.

    1995-11-01

    Spectroscopic investigations of the x-ray emission of plasmas heated by 120 ps, frequency doubled pulses from the JANUS Nd: glass laser are presented. High Z K-shell spectra emitted from slab targets heated to near 10 17 W cm -2 intensity are investigated. High resolution (γ/Δγ>5000) x-ray spectra of multicharged ions of H-like Ti, Co, Ni, Cu, and also H-like Sc in the spectral range 1.5--3.0 angstrom are obtained in single laser shots using a spherically bent Mica crystal spectrograph with a 186 mm radius of curvature. The spectra- have one dimensional spatial resolution of about 25μm and indicate that the size of the emission zone of the resonance, transitions is 2 keV and density∼10 22 cm -3 . These experiments demonstrate that with modest laser energy, plasmas heated by high-intensity 120 ps lasers provide a very bright source of hard ∼8 keV x-ray emission

  15. Quinoline-Flanked Diketopyrrolopyrrole Copolymers Breaking through Electron Mobility over 6 cm2 V-1 s-1 in Flexible Thin Film Devices.

    Science.gov (United States)

    Ni, Zhenjie; Dong, Huanli; Wang, Hanlin; Ding, Shang; Zou, Ye; Zhao, Qiang; Zhen, Yonggang; Liu, Feng; Jiang, Lang; Hu, Wenping

    2018-03-01

    Herein, the design and synthesis of novel π-extended quinoline-flanked diketopyrrolopyrrole (DPP) [abbreviated as QDPP] motifs and corresponding copolymers named PQDPP-T and PQDPP-2FT for high performing n-type organic field-effect transistors (OFETs) in flexible organic thin film devices are reported. Serving as DPP-flankers in backbones, quinoline is found to effectively tune copolymer optoelectric properties. Compared with TDPP and pyridine-flanked DPP (PyDPP) analogs, widened bandgaps and strengthened electron deficiency are achieved. Moreover, both hole and electron mobility are improved two orders of magnitude compared to those of PyDPP analogs (PPyDPP-T and PPyDPP-2FT). Notably, featuring an all-acceptor-incorporated backbone, PQDPP-2FT exhibits electron mobility of 6.04 cm 2 V -1 s -1 , among the highest value in OFETs fabricated on flexible substrates to date. Moreover, due to the widened bandgap and strengthened electron deficiency of PQDPP, n-channel on/off ratio over 10 5 with suppressed hole transport is first realized in the ambipolar DPP-based copolymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Performance of a 64-channel, 3.2×3.2 cm2 SiPM tile for TOF-PET application

    International Nuclear Information System (INIS)

    Ferri, Alessandro; Acerbi, Fabio; Gola, Alberto; Piemonte, Claudio; Paternoster, Giovanni; Zorzi, Nicola

    2016-01-01

    In this work, we present a new 3.2×3.2 cm 2 detector tile, composed of 8×8 single SiPMs, having a regular 4 mm pitch in both the X and Y directions. The tile fill factor is 85%. We produced two versions of the tile with different SiPM technologies: RGB-HD and NUV. The first one features square micro-cells with 25 µm pitch, a PDE peaked at 550 nm and a DCR of 300 kHz/mm 2 , at 20 °C and at maximum detection efficiency. The second one features micro-cells with 40 µm pitch and a PDE peaked in the blue part of the spectrum. The dark count rate at 20 °C and at maximum PDE is 100 kHz/mm 2 . In this work, we show the energy and timing resolution measurements at 511 keV obtained coupling the two tiles to an 8×8 LYSO array with a pixel size of 4×4×22 mm 3 , perfectly matching the photo-detector array.

  17. First operation and performance of a 200 lt double phase LAr LEM-TPC with a 40x76 $\\cm^2$ readout

    CERN Document Server

    Badertscher, A; Degunda, U; Epprecht, L; Gendotti, A; Horikawa, S; Knecht, L; Natterer, D Lussi G; Nguyen, K; Resnati, F; Rubbia, A; Viant, T

    2013-01-01

    In this paper we describe the design, construction, and operation of a first large area double-phase liquid argon Large Electron Multiplier Time Projection Chamber (LAr LEM-TPC). The detector has a maximum drift length of 60 cm and the readout consists of a $40\\times 76$ cm$^2$ LEM and 2D projective anode to multiply and collect drifting charges. Scintillation light is detected by means of cryogenic PMTs positioned below the cathode. To record both charge and light signals, we have developed a compact acquisition system, which is scalable up to ton-scale detectors with thousands of charge readout channels. The acquisition system, as well as the design and the performance of custom-made charge sensitive preamplifiers, are described. The complete experimental setup has been operated for a first time during a period of four weeks at CERN in the cryostat of the ArDM experiment, which was equipped with liquid and gas argon purification systems. The detector, exposed to cosmic rays, recorded events with a single-ch...

  18. Performance of n-in-p pixel detectors irradiated at fluences up to $5x10^{15} n_{eq}/cm^{2}$ for the future ATLAS upgrades

    CERN Document Server

    INSPIRE-00219560; La Rosa, A.; Nisius, R.; Pernegger, H.; Richter, R.H.; Weigell, P.

    We present the results of the characterization of novel n-in-p planar pixel detectors, designed for the future upgrades of the ATLAS pixel system. N-in-p silicon devices are a promising candidate to replace the n-in-n sensors thanks to their radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. The n-in-p modules presented here are composed of pixel sensors produced by CiS connected by bump-bonding to the ATLAS readout chip FE-I3. The characterization of these devices has been performed with the ATLAS pixel read-out systems, TurboDAQ and USBPIX, before and after irradiation with 25 MeV protons and neutrons up to a fluence of 5x10**15 neq /cm2. The charge collection measurements carried out with radioactive sources have proven the feasibility of employing this kind of detectors up to these particle fluences. The collected charge has been measured to be for any fluence in excess of twice the value of the FE-I3 threshold, tuned to 3200 e. The first result...

  19. Morphological analysis of second-intention wound healing in rats submitted to 16 J/cm 2 λ 660-nm laser irradiation

    Directory of Open Access Journals (Sweden)

    Gonzaga Ribeiro Maria

    2009-01-01

    Full Text Available Background and Objectives : Low-level laser therapy (LLLT has been extensively applied to improve wound healing due to some biostimulatory properties presented by laser arrays apparently able to accelerate the cicatricial repair of soft tissue injuries. However, many controversial results have been reported in the literature, probably as a result of the wide sort of different protocols of photobiomodulation employed in those experiments. The goal of this study was to investigate the effect of a low-dose protocol of LLT on the intensity of the inflammatory response and the pattern of collagen fibers′ deposition during second-intention wound healing in rodents. Materials and Methods : Standard-sized wounds were carried out in the back of 24 male rats. Half of them underwent LLLT treatment (16 J/cm 2 at 660 nm delivered for 7 days. Eight and 14 days after the wounds were performed, the repairing area was removed and stained in HE and Masson′s trichrome, and the inflammatory response, epithelization, and collagen fiber depositions were evaluated. Results : We found that LLLT was able to slightly reduce the intensity of the inflammatory reaction as well as to enhance substantially the epithelization process at both 8 th and 14 th days. In addition, it also appeared to stimulate the deposition of collagen fibers at the final stages of wound healing. Conclusions : The LLLT protocol tested in this study resulted in some improvements in second-intention wound healing in rodents.

  20. NbN/AlN/NbN tunnel junctions with high current density up to 54 kA/cm2

    International Nuclear Information System (INIS)

    Wang, Z.; Kawakami, A.; Uzawa, Y.

    1997-01-01

    We report on progress in the development of high current density NbN/AlN/NbN tunnel junctions for applications as submillimeter wave superconductor-insulator-superconductor mixers. A very high current density up to 54 kA/cm 2 , roughly an order of magnitude larger than any reported results for all-NbN tunnel junctions, was achieved in the junctions with about 1 nm thick AlN barriers. The magnetic field and temperature dependence of critical supercurrents were measured to investigate the Josephson tunneling behavior of critical supercurrents in the high-J c junctions. The junctions showed high-quality junction characteristics with a large gap voltage of 5 mV and sharp quasiparticle current rise (ΔV g =0.1 mV). The R sg /R N ratio was about 5 with a V m value of 14 mV measured at 4.2 K. copyright 1997 American Institute of Physics

  1. Evaluation of a postulated loss of coolant accident (LOCA) due to a 160 cm2 break in a cold leg of Angra 2 nuclear power plant

    International Nuclear Information System (INIS)

    Azevedo, Carlos Vicente Goulart de; Palmieri, Elcio Tadeu; Aronne, Ivan Dionysio

    2002-01-01

    The development of a qualified full nodalization of Angra2 NPP for RELAP5/Mod 3.2.2 gamma, aiming at the evaluation of a comprehensive number of accidents and transients, thus providing suitable safety analysis support for licensing purposes, is being carried out within the framework of CNEN internal technical cooperation, involving some of its institutes (CDTN, IPEN and IEN) and the Reactors Coordination (CODRE). This work presents a simulation of a postulated Angra2 small cold leg break loss of coolant accident (SBLOCA). A 160 cm 2 break is supposed to occur at one cold leg between the main coolant pump and the reactor vessel and is described in the Angra2 Final Safety Analysis Report, section 15.6.4.1.3.4. The simulation of several types of transients and accidents is necessary to verify the adequate performance of the modeled logic and systems. In general, the analysis of such and accident allows to demonstrate the safety Injection System performance and the reliable transition between the high pressure safety injection, the accumulator injection and the residual heat removal phases. Furthermore, it is assumed that some components are out of service due to fail or repair in order to make a conservative analysis. The results showed a compatible behavior of the molded systems and that the simulated Emergency Core Cooling System was able to provide sufficient cooling to avoid any damage to the core. (author)

  2. Ion acceleration in electrostatic field of charged cavity created by ultra-short laser pulses of 1020-1021 W/cm2

    Science.gov (United States)

    Bychenkov, V. Yu.; Singh, P. K.; Ahmed, H.; Kakolee, K. F.; Scullion, C.; Jeong, T. W.; Hadjisolomou, P.; Alejo, A.; Kar, S.; Borghesi, M.; Ter-Avetisyan, S.

    2017-01-01

    Ion acceleration resulting from the interaction of ultra-high intensity and ultra-high contrast (˜10-10) laser pulses with thin A l foil targets at 30° angle of laser incidence is studied. Proton maximum energies of 30 and 18 MeV are measured along the target normal rear and front sides, respectively, showing intensity scaling as Ib . For the target front bf r o n t= 0.5-0.6 and for the target rear br e a r= 0.7-0.8 is observed in the intensity range 1020-1021 W/cm2. The fast scaling from the target rear ˜I0.75 can be attributed enhancement of laser energy absorption as already observed at relatively low intensities. The backward acceleration of the front side protons with intensity scaling as ˜I0.5 can be attributed to the to the formation of a positively charged cavity at the target front via ponderomotive displacement of the target electrons at the interaction of relativistic intense laser pulses with a solid target. The experimental results are in a good agreement with theoretical predictions.

  3. Aqueous Alteration of Carbonaceous Chondrites: New Insights from Comparative Studies of Two Unbrecciated CM2 Chondrites, Y 791198 and ALH 81002

    Science.gov (United States)

    Chizmadia, L. J.; Brearley, A. J.

    2004-01-01

    Carbonaceous chondrites are an important resource for understanding the physical and chemical conditions in the early solar system. In particular, a long-standing question concerns the role of water in the cosmochemical evolution of carbonaceous chondrites. It is well established that extensive hydration of primary nebular phases occurred in the CM and CI chondrites, but the location where this alteration occurred remains controversial. In the CM2 chondrites, hydration formed secondary phases such as serpentine, tochilinite, pentlandite, carbonate and PCP. There are several textural observations which suggest that alteration occurred before the accretion of the final CM parent asteroid, i.e. preaccretionary alteration. Conversely, there is a significant body of evidence that supports parent-body alteration. In order to test these two competing hypotheses further, we studied two CM chondrites, Y-791198 and ALH81002, two meteorites that exhibit widely differing degrees of aqueous alteration. In addition, both meteorites have primary accretionary textures, i.e. experienced minimal asteroidal brecciation. Brecciation significantly complicates the task of unraveling alteration histories, mixing components that have been altered to different degrees from different locations on the same asteroidal parent body. Alteration in Y-791198 is mostly confined to chondrule mesostases, FeNi metal and fine-grained matrix and rims. In comparison, the primary chondrule silicates in ALH81002 have undergone extensive replacement by secondary hydrous phases. This study focuses on compositional and textural relationships between chondrule mesostasis and the associated rim materials. Our hypothesis is: both these components are highly susceptible to aqueous alteration and should be sensitive recorders of the alteration process. For parent body alteration, we expect systematic coupled mineralogical and compositional changes in rims and altered mesostasis, as elemental exchange between these

  4. 10.23  Mcps laser pseudo-code ranging system with 0.33  mm (1σ) pseudo-range measurement precision.

    Science.gov (United States)

    Yu, Xiaonan; Tong, Shoufeng; Zhang, Lei; Dong, Yan; Zhao, Xin; Qiao, Yue

    2017-07-01

    The inter-satellite laser link is the backbone of the next inter-satellite information network, and ranging and communication are the main functions of the inter-satellite laser link. This study focuses on the inter-satellite laser ranging based on the pseudo-code correlation technology. In this paper, several typical laser-ranging methods have been compared and we determined that the laser pseudo-code ranging architecture is more suitable for the inter-satellite laser communication link. The pseudo-code ranging system is easy to combine with a digital communication system, and we used it to calculate integer ambiguity by modulating the time information. The main challenge of the ranging system is range precision, which is the main focus of this paper. First, the framework of the pseudo-code ranging system is introduced; the ranging architecture of dual one-way ranging is used to eliminate the clock error between the two transceivers, and then the uncertainty of the phase detector is analyzed. In the analysis, the carrier to noise ratio and the ranging code rate are constrained by the laser communication link margin and the electronic hardware limitation. Therefore, the relationship between the sampling depth and the phase detector uncertainty is verified. A series of optical fiber channel laser pseudo-code ranging experiments demonstrated the effects of sampling depth on the ranging precision. By adjusting the depth of storage, such as the depth of 1.6 Mb, we obtained a pseudo-range measurement precision of 0.33 mm (1σ), which is equivalent to 0.0001 times code subdivision of 10.23 Mcps pseudo-code. This paper has achieved high precision in a pseudo-range measurements, which is the foundation of the inter-satellite laser link.

  5. Comparison of the clinical course of Japanese MM1-type sporadic Creutzfeldt-Jakob disease between subacute spongiform encephalopathy and panencephalopathic-type.

    Science.gov (United States)

    Iwasaki, Yasushi; Tatsumi, Shinsui; Mimuro, Maya; Kitamoto, Tetsuyuki; Yoshida, Mari

    2014-06-01

    Approximately half of Japanese sporadic Creutzfeldt-Jakob disease (sCJD) cases show panencephalopathic-type (PE-type) pathology, which is a rare subtype in North Americans and Europeans. Until now, the differences in the clinical course between subacute spongiform encephalopathy (SSE) cases and PE-type cases have been unclear. To investigate the clinical course of both subtypes, clinical findings from 42 Japanese MM1-type sCJD cases (20 SSE cases and 22 PE-type cases) were retrospectively evaluated by statistical analysis. No significant differences could be found regarding age at disease onset, the period between disease onset and first observation of myoclonus, the period between disease onset and the first observation of periodic sharp-wave complexes on electroencephalogram, or the period between disease onset and progression to the akinetic mutism state - whereas total disease duration and the period between the akinetic mutism state and death were significantly longer in PE-type cases. The prolonged disease duration was induced by the extended survival period in the akinetic mutism state. There was a statistically significant difference between the two series regarding performance of tube-feeding, but no statistically significant difference regarding performance of tracheotomy or gastrostomy. None of the cases received mechanical ventilation. We speculate that the most crucial factor of the prolonged survival period of Japanese sCJD cases, particularly in the PE-type, is that the introduction of tube-feeding in the akinetic mutism state leads to the stabilization of the patient's general condition. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Relation between clinical findings and progression of cerebral cortical pathology in MM1-type sporadic Creutzfeldt-Jakob disease: proposed staging of cerebral cortical pathology.

    Science.gov (United States)

    Iwasaki, Yasushi; Tatsumi, Shinsui; Mimuro, Maya; Kitamoto, Tetsuyuki; Hashizume, Yoshio; Yoshida, Mari

    2014-06-15

    In our pathologic observation of the cerebral cortex including the neocortex, hippocampus, and limbic cortex in 43 Japanese patients with MM1-type sporadic Creutzfeldt-Jakob disease, the earliest pathologic finding was spongiform change and next was gliosis. Subsequently, neuropil rarefaction appeared, followed by neuron loss. On the basis of these observations, we propose the following cortical pathologic staging: Stage I, spongiform change; Stage II, hypertrophic astrocytosis; Stage III, neuropil rarefaction; Stage IV, neuron loss; Stage V, status spongiosus; and Stage VI, large cavity formation. We also suggest a more simple staging classification: Stages I and II, mild; Stages III and IV, moderate; and Stages V and VI, severe involvement. Based on statistical analysis of the cases, strong correlation coefficients were obtained between the neocortical and limbic pathologic stage and both total disease duration and brain weight. We estimated that the first observation times of cortical hyperintensity on diffusion-weighted images of magnetic resonance imaging, myoclonus, and periodic sharp wave complexes on the electroencephalogram approximately correspond to the early phase of Stage II of the neocortex. The time to reach the akinetic mutism state approximately corresponds to the middle phase of Stage II of the neocortex. Therefore, we think that approximate clinical manifestations at death, total disease duration, and brain weight can be estimated according to the pathologic stage of the neocortex or limbic cortex. Panencephalopathic-type pathology appeared approximately 12 months after disease onset, and this time approximately corresponds to the middle phase of Stage III of the neocortex. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. 2,7-Diphenyl[1]benzothieno[3,2-b]benzothiophene, a new organic semiconductor for air-stable organic field-effect transistors with mobilities up to 2.0 cm2 V(-1) s(-1).

    Science.gov (United States)

    Takimiya, Kazuo; Ebata, Hideaki; Sakamoto, Katsuhiro; Izawa, Takafumi; Otsubo, Tetsuo; Kunugi, Yoshihito

    2006-10-04

    Vapor-deposited thin films of a newly developed sulfur-containing heteroarene, 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DPh-BTBT), were used as an active layer of OFETs, which showed excellent FET characteristics in ambient conditions with mobilities of approximately 2.0 cm2 V-1 s-1 and Ion/Ioff of 107.

  8. Test report: Preliminary tests for the High Flux Reactor: Experimental determination of flow redistribution conditions at pressures between 4 and 5 kg/cm2 abs in a rectangular channel 2 mm thick and 60 cm long

    International Nuclear Information System (INIS)

    Schleisiek, K.; Dumaine, J.C.

    1989-01-01

    In the context of safety research for the OSIRIS reactor, tests have been performed on the Super BOB cell with a view to determining experimentally the internal characteristics (or ''S'' curves) of a channel with a rectangular heating cross-section 2 x 38 mm and 600 mm long. During these tests the maximum pressure at the channel exit was brought to 3 kg/cm 2 abs. The pressurization level in the High Flux Reactor will be higher. That is why tests have been carried out at maximum pressure of 5 kg/cm 2 abs allowable on the ''super BOB'' loop without modifying it. The first objective of this test series was to determine the ''S'' curves and the exchange coefficients experimentally. This document discusses the test conditions and test results

  9. First charge collection and position-precision data on the medium-resistivity silicon strip detectors before and after neutron irradiation up to 2x1014 n/cm2

    International Nuclear Information System (INIS)

    Li Zheng; Dezillie, B.; Eremin, V.; Li, C.J.; Verbitskaya, E.

    1999-01-01

    Test strip detectors of 125 μm, 500 μm, and 1 mm pitches with about 1 cm 2 areas have been made on medium-resistivity silicon wafers (1.3 and 2.7 kΩ cm). Detectors of 500 μm pitch have been tested for charge collection and position precision before and after neutron irradiation (up to 2x10 14 n/cm 2 ) using 820 and 1030 nm laser lights with different beam-spot sizes. It has been found that for a bias of 250 V a strip detector made of 1.3 kΩ cm (300 μm thick) can be fully depleted before and after an irradiation of 2x10 14 n/cm 2 . For a 500 μm pitch strip detector made of 2.7 kΩ cm tested with an 1030 nm laser light with 200 μm spot size, the position reconstruction error is about 14 μm before irradiation, and 17 μm after about 1.7x10 13 n/cm 2 irradiation. We demonstrated in this work that medium resistivity silicon strip detectors can work just as well as the traditional high-resistivity ones, but with higher radiation tolerance. We also tested charge sharing and position reconstruction using a 1030 nm wavelength (300 μm absorption length in Si at RT) laser, which provides a simulation of MIP particles in high-physics experiments in terms of charge collection and position reconstruction

  10. High Charge-Carrier Mobility of 2.5 cm(2) V(-1) s(-1) from a Water-Borne Colloid of a Polymeric Semiconductor via Smart Surfactant Engineering.

    Science.gov (United States)

    Cho, Jangwhan; Cheon, Kwang Hee; Ahn, Hyungju; Park, Kwang Hun; Kwon, Soon-Ki; Kim, Yun-Hi; Chung, Dae Sung

    2015-10-07

    Semiconducting polymer nanoparticles dispersed in water are synthesized by a novel method utilizing non-ionic surfactants. By developing a smart surfactant engineering technique involving a selective post-removal process of surfactants, an unprecedentedly high mobility of 2.51 cm(2) V(-1) s(-1) from a water-borne colloid is demonstrated for the first time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Ionization rates and harmonic generation for H interacting with laser pulses of λ = 1064 nm and peak intensities in the range 2 x 1013-2 x 1014 W cm-2

    International Nuclear Information System (INIS)

    Dionissopoulou, S.; Mercouris, Th.; Nicolaides, C.A.

    1996-01-01

    We applied the state-specific expansion approach (SSEA) to the solution of the time-dependent Schroedinger equation describing the interaction of H with laser pulses of λ = 1064 nm and peak intensities I 0 = 2 x 10 13 , 6 x 10 13 , 1 x 10 14 and 2 x 10 14 W cm -2 , and computed ionization rates and high-order harmonic spectra. For the first three cases, our results are compared with those of Krause and co-workers (Krause J L, Schafer K J and Kulander K C 1992 Phys. Rev. A45 3998) who employed the grid method. Whereas for I 0 = 1 x 10 14 W cm -2 convergence difficulties were reported for the grid method, no such difficulties were found for the SSEA. Given this fact, we tackled the problem of computing the harmonic spectrum for I 0 = 2 x 10 14 W cm -2 . This spectrum shows a cut-off at the 65th harmonic (3.17 U p + I p ) and an extended plateau containing low-intensity harmonics up to the 181st. The ionization rate is 1.7 x 10 13 s -1 while at the end of the pulse 19.5% of the system is in the 1s ground state and 2.6% in the bound states up to n = 20, l 19. (author)

  12. Influence of Cu(In,Ga)(Se,S)2 surface treatments on the properties of 30 × 30 cm2 large area modules with atomic layer deposited Zn(O,S) buffers

    International Nuclear Information System (INIS)

    Merdes, S.; Steigert, A.; Ziem, F.; Lauermann, I.; Klenk, R.; Hergert, F.; Kaufmann, C.A.; Schlatmann, R.

    2015-01-01

    We report the effect of Cu(In,Ga)(Se,S) 2 absorber surface treatments on the properties of atomic layer deposited-Zn(O,S) buffered 30 × 30 cm 2 large area modules. The absorber is prepared by the sequential process. H 2 O and KCN solution treatments are investigated. The absorber surface treatment is found to influence significantly the open circuit voltage and the fill factor of the full modules. Light soaking related metastabilities are also found to depend on the type of treatment. While both H 2 O and KCN treatments are efficient at removing Se-oxides and Na 2 HCO 3 , the KCN treatment is found to remove additionally Ga-oxides and elemental Se that are detected on the surface of the absorber. A 30 × 30 cm 2 module aperture efficiency up to 12.3% could be achieved with KCN surface treatment of the absorber. - Highlights: • The Cu(In,Ga)(Se,S) 2 surface influences the Zn(O,S)-buffered module performance. • Surface treatment by H 2 O efficiently removes Se-oxides and sodium compounds. • KCN treatment of the absorber removes Se-oxides, Ga-oxides and elemental Se. • The devices' light soaking behavior depends on the absorber's surface chemistry. • A 30 × 30 cm 2 module efficiency of 12.3% is achieved with KCN treatment

  13. Flow regimes and heat transfer modes identification in ANGRA 2 core, during small break in the primary loop with area of 100 cm2, simulated with RELAP5 code

    International Nuclear Information System (INIS)

    Borges, Eduardo M.; Sabundjian, Gaiane

    2015-01-01

    Identifying the flow regimes and the heat transfer modes is important for the analysis of accidents such as the Loss-of-Coolant Accident (LOCA). The aim of this paper is to identify the flow regimes, the heat transfer modes, and the correlations used in the RELAP5/MOD3.2.gama code in ANGRA 2 during the Small-Break Loss-of-Coolant Accident (SBLOCA) with a 100cm 2 -rupture area in the cold leg of primary loop. The Chapter 15 of the Final Safety Analysis Report of ANGRA 2 (FSAR - A2) reports this specific kind of accident. The results from this work demonstrated the several flow regimes and heat transfer modes that can be present in the core of ANGRA 2 during the postulated accident. (author)

  14. Identification of flow regimes and heat transfer modes in Angra-2 core during the simulation of the small break loss of coolant accident of 250 cm2 in the cold leg of primary loop using RELAP5 code

    International Nuclear Information System (INIS)

    Borges, Eduardo M.; Sabundjian, Gaiane

    2017-01-01

    The aim of this paper is to identify the flow regimes, the heat transfer modes, and the correlations used by RELAP5/MOD3.2. gamma code in Angra-2 during the Small-Break Loss-of-Coolant Accident (SBLOCA) with a 250cm 2 of rupture area in the cold leg of primary loop. The Chapter 15 of the Final Safety Analysis Report of Angra-2 (FSAR-A2) reports this specific kind of accident. The results from this work demonstrated the several flow regimes and heat transfer modes that can be present in the core of Angra-2 during the postulated accident. The results obtained for Angra-2 nuclear reactor core during the postulated accident were satisfactory when compared with the FSAR-A2. Additionally, the results showed the correct actuation of the ECCS guaranteeing the integrity of the reactor core. (author)

  15. Over 15 MA/cm2 of critical current density in 4.8 µm thick, Zr-doped (Gd,Y)Ba2Cu3Ox superconductor at 30 K, 3T.

    Science.gov (United States)

    Majkic, Goran; Pratap, Rudra; Xu, Aixia; Galstyan, Eduard; Selvamanickam, Venkat

    2018-05-03

    An Advanced MOCVD (A-MOCVD) reactor was used to deposit 4.8 µm thick (Gd,Y)BaCuO tapes with 15 mol% Zr addition in a single pass. A record-high critical current density (J c ) of 15.11 MA/cm 2 has been measured over a bridge at 30 K, 3T, corresponding to an equivalent (I c ) value of 8705 A/12 mm width. This corresponds to a lift factor in critical current of ~11 which is the highest ever reported to the best of author's knowledge. The measured critical current densities at 3T (B||c) and 30, 40 and 50 K, respectively, are 15.11, 9.70 and 6.26 MA/cm 2 , corresponding to equivalent Ic values of 8705, 5586 and 3606 A/12 mm and engineering current densities (J e ) of 7068, 4535 and 2928 A/mm 2 . The engineering current density (J e ) at 40 K, 3T is 7 times higher than that of the commercial HTS tapes available with 7.5 mol% Zr addition. Such record-high performance in thick films (>1 µm) is a clear demonstration that growing thick REBCO films with high critical current density (J c ) is possible, contrary to the usual findings of strong J c degradation with film thickness. This achievement was possible due to a combination of strong temperature control and uniform laminar flow achieved in the A-MOCVD system, coupled with optimization of BaZrO 3 nanorod growth parameters.

  16. The hydrocarbon-degrading marine bacterium Cobetia sp. strain MM1IDA2H-1 produces a biosurfactant that interferes with quorum sensing of fish pathogens by signal hijacking

    Science.gov (United States)

    Ibacache-Quiroga, C; Ojeda, J; Espinoza-Vergara, G; Olivero, P; Cuellar, M; Dinamarca, M A

    2013-01-01

    Summary Biosurfactants are produced by hydrocarbon-degrading marine bacteria in response to the presence of water-insoluble hydrocarbons. This is believed to facilitate the uptake of hydrocarbons by bacteria. However, these diffusible amphiphilic surface-active molecules are involved in several other biological functions such as microbial competition and intra-or inter-species communication. We report the isolation and characterization of a marine bacterial strain identified as Cobetia sp. MM1IDA2H-1, which can grow using the sulfur-containing heterocyclic aromatic hydrocarbon dibenzothiophene (DBT). As with DBT, when the isolated strain is grown in the presence of a microbial competitor, it produces a biosurfactant. Because the obtained biosurfactant was formed by hydroxy fatty acids and extracellular lipidic structures were observed during bacterial growth, we investigated whether the biosurfactant at its critical micelle concentration can interfere with bacterial communication systems such as quorum sensing. We focused on Aeromonas salmonicida subsp. salmonicida, a fish pathogen whose virulence relies on quorum sensing signals. Using biosensors for quorum sensing based on Chromobacterium violaceum and Vibrio anguillarum, we showed that when the purified biosurfactant was mixed with N-acyl homoserine lactones produced by A. salmonicida, quorum sensing was inhibited, although bacterial growth was not affected. In addition, the transcriptional activities of A. salmonicida virulence genes that are controlled by quorum sensing were repressed by both the purified biosurfactant and the growth in the presence of Cobetia sp. MM1IDA2H-1. We propose that the biosurfactant, or the lipid structures interact with the N-acyl homoserine lactones, inhibiting their function. This could be used as a strategy to interfere with the quorum sensing systems of bacterial fish pathogens, which represents an attractive alternative to classical antimicrobial therapies in fish

  17. AlGaN/GaN heterostructures with an AlGaN layer grown directly on reactive-ion-etched GaN showing a high electron mobility (>1300 cm2 V-1 s-1)

    Science.gov (United States)

    Yamamoto, Akio; Makino, Shinya; Kanatani, Keito; Kuzuhara, Masaaki

    2018-04-01

    In this study, the metal-organic-vapor-phase-epitaxial growth behavior and electrical properties of AlGaN/GaN structures prepared by the growth of an AlGaN layer on a reactive-ion-etched (RIE) GaN surface without regrown GaN layers were investigated. The annealing of RIE-GaN surfaces in NH3 + H2 atmosphere, employed immediately before AlGaN growth, was a key process in obtaining a clean GaN surface for AlGaN growth, that is, in obtaining an electron mobility as high as 1350 cm2 V-1 s-1 in a fabricated AlGaN/RIE-GaN structure. High-electron-mobility transistors (HEMTs) were successfully fabricated with AlGaN/RIE-GaN wafers. With decreasing density of dotlike defects observed on the surfaces of AlGaN/RIE-GaN wafers, both two-dimensional electron gas properties of AlGaN/RIE-GaN structures and DC characteristics of HEMTs were markedly improved. Since dotlike defect density was markedly dependent on RIE lot, rather than on growth lot, surface contaminations of GaN during RIE were believed to be responsible for the formation of dotlike defects and, therefore, for the inferior electrical properties.

  18. Preparation of Nd-Fe-B/α-Fe nano-composite thick-film magnets on various substrates using PLD with high laser energy density above 10 J/cm2

    Science.gov (United States)

    Nakano, M.; Kondo, H.; Yamashita, A.; Yanai, T.; Itakura, M.; Fukunaga, H.

    2018-05-01

    PLD (Pulsed Laser Deposition) method with high laser energy density (LED) above 10 J/cm2 followed by a flash annealing enabled us to obtain isotropic nano-composite thick-film magnets with (BH)max ≧ 80 kJ/m3 on polycrystalline Ta substrates. We also have demonstrated that a dispersed structure composed of α-Fe together with Nd2Fe14B phases with the average grain diameter of approximately 20 nm could be formed on the Ta substrates. In this study, we tried to enhance the (BH)max value by controlling the microstructure due to the usage of different metal based substrates with each high melting point such as Ti, Nb, and W. Although it was difficult to vary the microstructure and to improve the magnetic properties of the films deposited on the substrates, we confirmed that isotropic thick-film magnets with (BH)max ≧ 80 kJ/m3 based on the nano-dispersed α-Fe and Nd2Fe14B phases could be obtained on various metal substrates with totally different polycrystalline structure. On the other hand, the use of a glass substrate lead to the deterioration of magnetic properties of a film prepared using the same preparation process.

  19. Charge state and incident energy dependence of K X-ray emission as a function of target thickness for 50-165 MeV Cu ions incident on 11-250 μg/cm2 Cu

    International Nuclear Information System (INIS)

    Momoi, T.; Shima, K.; Umetani, K.; Moriyama, M.; Ishihara, T.; Mikumo, T.

    1986-01-01

    Thin self-supporting Cu targets in 11-250 μg/cm 2 thickness were bombarded with 50-165 MeV Cu sup(qi + ) ions (7 + )+Cu. From the observed K X-ray yields, K-shell vacancy production cross sections averaged over the target thickness t of projectile sigmasub(KV) and target sigmasup(*)sub(KV) were separately derived taking into account the fluorescence yield that can be estimated from the Ksub(α) X-ray energy shift. When the values of sigmasub(KV) and sigmasup(*)sub(KV) are extrapolated to zero foil thickness, the K shell vacancy formed in the collision has been found to be equally shared between projectile and target in a single collision. With the increase of penetration depth, however, the values of sigmasup(*)sub(KV) are greater than those of sigmasub(KV) presumably due to electron transfer of a target K electron to the projectile K vacancy. The evolution process of projectile excited states as a function of target thickness and the resulting variation of projectile and target K X-ray emissions are discussed. (orig.)

  20. Cost analysis of negative-pressure wound therapy with instillation for wound bed preparation preceding split-thickness skin grafts for massive (>100 cm(2)) chronic venous leg ulcers.

    Science.gov (United States)

    Yang, C Kevin; Alcantara, Sean; Goss, Selena; Lantis, John C

    2015-04-01

    Massive (≥100 cm(2)) venous leg ulcers (VLUs) demonstrate very low closure rates with standard compression therapy and are costly to manage. Negative-pressure wound therapy (NPWT), followed by a split-thickness skin graft (STSG), can be a cost-effective alternative to this standard care. We performed a cost analysis of these two treatments. A retrospective review was performed of 10 ulcers treated with surgical debridement, 7 days of inpatient NPWT with topical antiseptic instillation (NPWTi), and STSG, with 4 additional days of inpatient NPWT bolster over the graft. Independent medical cost estimators were used to compare the cost of this treatment protocol with standard outpatient compression therapy. The average length of time ulcers were present before patients entered the study was 38 months (range, 3-120 months). Eight of 10 patients had complete VLU closure by 6 months after NPWTi with STSG. The 6-month costs of the proposed treatment protocol and standard twice-weekly compression therapy were estimated to be $27,000 and $28,000, respectively. NPWTi with STSG treatment is more effective for closure of massive VLUs at 6 months than that reported for standard compression therapy. Further, the cost of the proposed treatment protocol is comparable with standard compression therapy. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  1. Highly sensitive lactate biosensor by engineering chitosan/PVI-Os/CNT/LOD network nanocomposite.

    Science.gov (United States)

    Cui, Xiaoqiang; Li, Chang Ming; Zang, Jianfeng; Yu, Shucong

    2007-06-15

    A novel chitosan/PVI-Os(polyvinylimidazole-Os)/CNT(carbon nanotube)/LOD (lactate oxidase) network nanocomposite was constructed on gold electrode for detection of lactate. The composite was nanoengineered by selected matched material components and optimized composition ratio to produce a superior lactate sensor. Positively charged chitosan and PVI-Os were used as the matrix and the mediator to immobilize the negatively charged LOD and to enhance the electron transfer, respectively. CNTs were introduced as the essential component in the composite for the network nanostructure. FESEM (field emission scan electron microscopy) and electrochemical characterization demonstrated that CNT behaved as a cross-linker to network PVI and chitosan due to its nanoscaled and negative charged nature. This significantly improved the conductivity, stability and electroactivity for detection of lactate. The standard deviation of the sensor without CNT in the composite was greatly reduced from 19.6 to 4.9% by addition of CNTs. With optimized conditions the sensitivity and detection limit of the lactate sensor was 19.7 microA mM(-1)cm(-2) and 5 microM, respectively. The sensitivity was remarkably improved in comparison to the newly reported values of 0.15-3.85 microA mM(-1)cm(-2). This novel nanoengineering approach for selecting matched components to form a network nanostructure could be extended to other enzyme biosensors, and to have broad potential applications in diagnostics, life science and food analysis.

  2. Low-voltage back-gated atmospheric pressure chemical vapor deposition based graphene-striped channel transistor with high-κ dielectric showing room-temperature mobility > 11 000 cm2/V·s

    KAUST Repository

    Smith, Casey

    2013-07-23

    Utilization of graphene may help realize innovative low-power replacements for III-V materials based high electron mobility transistors while extending operational frequencies closer to the THz regime for superior wireless communications, imaging, and other novel applications. Device architectures explored to date suffer a fundamental performance roadblock due to lack of compatible deposition techniques for nanometer-scale dielectrics required to efficiently modulate graphene transconductance (gm) while maintaining low gate capacitance-voltage product (CgsVgs). Here we show integration of a scaled (10 nm) high-κ gate dielectric aluminum oxide (Al2O3) with an atmospheric pressure chemical vapor deposition (APCVD)-derived graphene channel composed of multiple 0.25 μm stripes to repeatedly realize room-temperature mobility of 11 000 cm 2/V·s or higher. This high performance is attributed to the APCVD graphene growth quality, excellent interfacial properties of the gate dielectric, conductivity enhancement in the graphene stripes due to low t ox/Wgraphene ratio, and scaled high-κ dielectric gate modulation of carrier density allowing full actuation of the device with only ±1 V applied bias. The superior drive current and conductance at Vdd = 1 V compared to other top-gated devices requiring undesirable seed (such as aluminum and poly vinyl alcohol)-assisted dielectric deposition, bottom gate devices requiring excessive gate voltage for actuation, or monolithic (nonstriped) channels suggest that this facile transistor structure provides critical insight toward future device design and process integration to maximize CVD-based graphene transistor performance. © 2013 American Chemical Society.

  3. Low-voltage back-gated atmospheric pressure chemical vapor deposition based graphene-striped channel transistor with high-κ dielectric showing room-temperature mobility > 11 000 cm2/V·s

    KAUST Repository

    Smith, Casey; Qaisi, Ramy M.; Liu, Zhihong; Yu, Qingkai; Hussain, Muhammad Mustafa

    2013-01-01

    Utilization of graphene may help realize innovative low-power replacements for III-V materials based high electron mobility transistors while extending operational frequencies closer to the THz regime for superior wireless communications, imaging, and other novel applications. Device architectures explored to date suffer a fundamental performance roadblock due to lack of compatible deposition techniques for nanometer-scale dielectrics required to efficiently modulate graphene transconductance (gm) while maintaining low gate capacitance-voltage product (CgsVgs). Here we show integration of a scaled (10 nm) high-κ gate dielectric aluminum oxide (Al2O3) with an atmospheric pressure chemical vapor deposition (APCVD)-derived graphene channel composed of multiple 0.25 μm stripes to repeatedly realize room-temperature mobility of 11 000 cm 2/V·s or higher. This high performance is attributed to the APCVD graphene growth quality, excellent interfacial properties of the gate dielectric, conductivity enhancement in the graphene stripes due to low t ox/Wgraphene ratio, and scaled high-κ dielectric gate modulation of carrier density allowing full actuation of the device with only ±1 V applied bias. The superior drive current and conductance at Vdd = 1 V compared to other top-gated devices requiring undesirable seed (such as aluminum and poly vinyl alcohol)-assisted dielectric deposition, bottom gate devices requiring excessive gate voltage for actuation, or monolithic (nonstriped) channels suggest that this facile transistor structure provides critical insight toward future device design and process integration to maximize CVD-based graphene transistor performance. © 2013 American Chemical Society.

  4. Results of charpy V-notch impact testing of structural steel specimens irradiated at ∼30 degrees C to 1 x 1016 neutrons/cm2 in a commercial reactor cavity

    International Nuclear Information System (INIS)

    Iskander, S.K.; Stoller, R.E.

    1997-04-01

    A capsule containing Charpy V-notch (CVN) and mini-tensile specimens was irradiated at ∼ 30 degrees C (∼ 85 degrees F) in the cavity of a commercial nuclear power plant to a fluence of 1 x 10 16 neutrons/cm 2 (> 1MeV). The capsule included six CVN impact specimens of archival High Flux Isotope Reactor A212 grade B ferritic steel and five CVN impact specimens of a well-studied A36 structural steel. This irradiation was part of the ongoing study of neutron-induced damage effects at the low temperature and flux experienced by reactor supports. The plant operators shut down the plant before the planned exposure was reached. The exposure of these specimens produced no significant irradiation-induced embrittlement. Of interest were the data on unirradiated specimens in the L-T orientation machined from a single plate of A36 structural steel, which is the same specification for the structural steel used in some reactor supports. The average CVN energy of five unirradiated specimens obtained from one region of the plate and tested at room temperature was ∼ 99 J, while the energy of 11 unirradiated specimens from other locations of the same plate was 45 J, a difference of ∼ 220%. The CVN impact energies for all 18 specimens ranged from a low of 32 J to a high of 111 J. Moreover, it appears that the University of Kansas CVN impact energy data of the unirradiated specimens at the 100-J level are shifted toward higher temperatures by about 20 K. The results were an example of the extent of scatter possible in CVN impact testing. Generic values for the CVN impact energy of A36 should be used with caution in critical applications

  5. An autopsied case of MM1 + MM2-cortical with thalamic-type sporadic Creutzfeldt-Jakob disease presenting with hyperintensities on diffusion-weighted MRI before clinical onset.

    Science.gov (United States)

    Iwasaki, Yasushi; Mori, Keiko; Ito, Masumi; Mimuro, Maya; Kitamoto, Tetsuyuki; Yoshida, Mari

    2017-02-01

    A 78-year-old Japanese man presented with rapidly progressive dementia and gait disturbances. Eight months before the onset of clinical symptoms, diffusion-weighted magnetic resonance imaging (DWI) demonstrated hyperintensities in the right temporal, right parietal and left medial occipital cortices. Two weeks after symptom onset, DWI showed extensive hyperintensity in the bilateral cerebral cortex, with regions of higher brightness that existed prior to symptom onset still present. Four weeks after clinical onset, periodic sharp wave complexes were identified on an electroencephalogram. Myoclonus was observed 8 weeks after clinical onset. The patient reached an akinetic mutism state and died 5 months after onset. Neuropathological examination showed widespread cerebral neocortical involvement of fine vacuole-type spongiform changes with large confluent vacuole-type spongiform changes. Spongiform degeneration with neuron loss and hypertrophic astrocytosis was also observed in the striatum and medial thalamus. The inferior olivary nucleus showed severe neuron loss with hypertrophic astrocytosis. Prion protein (PrP) immunostaining showed widespread synaptic-type PrP deposition with perivacuolar-type PrP deposition in the cerebral neocortex. Mild to moderate PrP deposition was also observed extensively in the basal ganglia, thalamus, cerebellum and brainstem, but it was not apparent in the inferior olivary nucleus. PrP gene analysis showed no mutations, and polymorphic codon 129 showed methionine homozygosity. Western blot analysis of protease-resistant PrP showed both type 1 scrapie type PrP (PrP Sc ) and type 2 PrP Sc . Based on the relationship between the neuroimaging and pathological findings, we speculated that cerebral cortical lesions with large confluent vacuoles and type 2 PrP Sc would show higher brightness and continuous hyperintensity on DWI than those with fine vacuoles and type 1 PrP Sc . We believe the present patient had a combined form of MM1

  6. Tank testing of a 2500-cm2 solar panel

    Science.gov (United States)

    Bever, R. S.; Staskus, J.

    1981-01-01

    A 50 cm by 50 cm solar array panel test patch was investigated for spacecraft charging and arcing effects. Bombardment with monochromatic electron was carried out. Some objectives of the test were: (1) to estimate at what voltage of electron bombardment arcing would be probable; (2) to find whether the arc's energy would be tolerable or damagingly large; (3) to try and separate thermal and photoeffects; and, (4) to see whether materials used were such as to minimize arcing. Some conclusions were: In sunlight the tracking data relay satellite's solar panel which has ceria glass on the front and conductive paint on the backside is probably a good design for reducing charge-up. In a geomagnetic substorm simulated in testing there will be arcing at the interconnects during eclipse and transitions into and out of eclipse in testing especially in view of the very cold temperatures that will be reached by this lightweight array. Ceria-doped glass is preferred to fused silica glass for reducing charge build up. The Kapton bare patch should still be conductively painted. The differential voltages on the panel determine when arcing first begins, and the electron beam voltages vary depending upon whether the metallic structure is directly grounded or semifloating.

  7. Amorphous nanostructuralization in HOPG by 1014 W cm-2 laser

    International Nuclear Information System (INIS)

    NISHIMURA, Yasuhiko; KITAGAWA, Yoneyoshi; MORI, Yoshitaka; ISHII, Katsuhiro; HANAYAMA, Ryohei; AZUMA, Hirozumi; HIOKI, Tatsumi; MOTOHIRO, Tomoyoshi; NISHI, Teppei; KOMEDA, Osamu; SEKINE, Takashi; SATO, Nakahiro; KURITA, Takashi; KAWASHIMA, Toshiyuki; KAN, Hirofumi; SUNAHARA, Atsushi; SENTOKU, Yasuhiko; MIURA, Eisuke

    2016-01-01

    This reports provide an amorphous nanostructuralization technique on the surface modification in Highly Oriented Pyrolytic Graphite (HOPG) by using a femtosecond laser. We showed, for the first time, that the surface of HOPG is changed to the amorphous nanostructuralization graphite by using a femtosecond laser-driven compression technique. Our results also suggest that the HOPG surface is changed until the deeper area from the surface by the laser-driven shock wave. A single shot of a femtosecond laser beam (1.27 ∼ 1.33×10 14 Wcm∼ 2 in intensity, with 2 mm-diameter, and 110 fs in pulse width) is irradiated under the vacuum ambience onto a 2 mm-thick of HOPG. The calculated impact pressures on a sample was 8.3 ∼ 8.7 GPa. Crystal structure in the HOPG were analyzed using a Raman spectroscopy and an X-ray diffraction, those analyzing depth from the surface were 50 nm and 350 μm, respectively. (paper)

  8. Eu9Cd4-xCM2+x-y□ySb9: Ca9Mn4Bi9-type structure stuffed with coinage metals (Cu, Ag, and Au) and the challenges with classical valence theory in describing these possible zintl phases.

    Science.gov (United States)

    Kazem, Nasrin; Hurtado, Antonio; Klobes, Benedikt; Hermann, Raphaël P; Kauzlarich, Susan M

    2015-02-02

    The synthesis, crystal structure, magnetic properties, and europium Mössbauer spectroscopy of the new members of the 9-4-9 Zintl family of Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb(9) (CM = coinage metal: Au, Ag, and Cu) are reported. These compounds crystallize in the Ca(9)Mn(4)Bi(9) structure type (9-4-9) with the 4g interstitial site almost half-occupied by coinage metals; these are the first members in the 9-4-9 family where the interstitial positions are occupied by a monovalent metal. All previously known compounds with this structure type include divalent interstitials where these interstitials are typically the same as the transition metals in the anionic framework. Single-crystal magnetic susceptibility data indicate paramagnetic behavior for all three compounds with antiferromagnetic ordering below 10 K (at 100 Oe) that shifts to lower temperature (x)CM(2+x-y)□(y)Sb(9) at 50 and 6.5 K in order to evaluate the valence of Eu cations. Although the Zintl formalism states that the five crystallographically distinct Eu sites in Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb9 should bear Eu(2+), the Mössbauer spectral isomer shifts are clearly indicative of both 2+ and 3+ valence of the Eu cations with the Cu- and Au-containing compounds showing higher amounts of Eu(3+). This electronic configuration leads to an excess of negative charge in these compounds that contradicts the expected valence-precise requirement of Zintl phases. The spectra obtained at 6.5 K reveal magnetic ordering for both Eu(2+) and Eu(3+). The field dependence of Eu(2+) indicates two distinct magnetic sublattices, with higher and lower fields, and of a small field for Eu(3+). The site symmetry of the five Eu sites is not distinguishable from the Mössbauer data.

  9. Polymeric bionanocomposite cast thin films with in situ laccase-catalyzed polymerization of dopamine for biosensing and biofuel cell applications.

    Science.gov (United States)

    Tan, Yueming; Deng, Wenfang; Li, Yunyong; Huang, Zhao; Meng, Yue; Xie, Qingji; Ma, Ming; Yao, Shouzhuo

    2010-04-22

    We report here on the facile preparation of polymer-enzyme-multiwalled carbon nanotubes (MWCNTs) cast films accompanying in situ laccase (Lac)-catalyzed polymerization for electrochemical biosensing and biofuel cell applications. Lac-catalyzed polymerization of dopamine (DA) as a new substrate was examined in detail by UV-vis spectroscopy, cyclic voltammetry, quartz crystal microbalance, and scanning electron microscopy. Casting the aqueous mixture of DA, Lac and MWCNTs on a glassy carbon electrode (GCE) yielded a robust polydopamine (PDA)-Lac-MWCNTs/GCE that can sense hydroquinone with 643 microA mM(-1) cm(-2) sensitivity and 20-nM detection limit (S/N = 3). The DA substrate yielded the best biosensing performance, as compared with aniline, o-phenylenediamine, or o-aminophenol as the substrate for similar Lac-catalyzed polymerization. Casting the aqueous mixture of DA, glucose oxidase (GOx), Lac, and MWCNTs on a Pt electrode yielded a robust PDA-GOx-Lac-MWCNTs/Pt electrode that exhibits glucose-detection sensitivity of 68.6 microA mM(-1) cm(-2). In addition, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) was also coimmobilized to yield a PDA-Lac-MWCNTs-ABTS/GCE that can effectively catalyze the reduction of O(2), and it was successfully used as the biocathode of a membraneless glucose/O(2) biofuel cell (BFC) in pH 5.0 Britton-Robinson buffer. The proposed biomacromolecule-immobilization platform based on enzyme-catalyzed polymerization may be useful for preparing many other multifunctional polymeric bionanocomposites for wide applications.

  10. Phase II, two-arm RTOG trial (94-11) of bischloroethyl-nitrosourea plus accelerated hyperfractionated radiotherapy (64.0 or 70.4 Gy) based on tumor volume (> 20 or ≤ 20 cm2, respectively) in the treatment of newly-diagnosed radiosurgery-ineligible glioblastoma multiforme patients

    International Nuclear Information System (INIS)

    Coughlin, C.; Scott, C.; Langer, C.; Coia, L.; Curran, W.; Rubin, P.

    2000-01-01

    Purpose: To compare survivorship, and acute and delayed toxicities following radiation therapy (RT) of radiosurgery-ineligible glioblastoma multiforme (GBM) patients treated with tumor volume-influenced, high-dose accelerated, hyperfractionated RT plus bischloroethyl-nitrosourea (BCNU), using prior RTOG malignant glioblastoma patients as historical controls. Methods and Materials: One hundred four of 108 patients accrued from June 1994 through May 1995 from 26 institutions were analyzable. Patients were histologically confirmed with GBM, and previously untreated. Treatment assignment (52 patients/arm) was based on tumor mass (TM), defined as the product of the maximum diameter and greatest perpendicular dimension of the titanium-gadolinium-enhanced postoperative MRI: Arm A, 64 Gy, TM > 20 cm 2 ; or Arm B, 70.4 Gy, TM ≤ 20 cm 2 . Both Arms A and B received BCNU (80 mg/m 2 , under hyperhydration) days 1-3, 56-58, then 4 cycles, each 8 weeks, for a total of 6 treatment series. Results: During the 24 months immediately post-treatment, the overall median survival was 9.1 months in Arm A (64 Gy) and 11.0 months in Arm B (70.4 Gy). Median survival in recursive partitioning analysis (RPA) Class III/IV was 10.4 months in Arm A and 12.2 months in Arm B, while RPA Class V/VI was 7.6 months in Arm A and 6.1 months in Arm B. There were no grade 4 neurological toxicities in Arm A; 2 grade 4 neurological toxicities were observed in Arm B (1 motor deficit, 1 necrosis at 157 days post-treatment). Conclusion: This strategy of high-dose, accelerated hyperfractionated radiotherapy shortens overall RT treatment times while allowing dose escalation, and it provides the potential for combination with currently available, as well as newer, chemotherapy agents. Survival is comparable with previously published RTOG data, and toxicities are within acceptable limits.

  11. Geometry and bonding in the ground and lowest triplet state of D{sub 6h} symmetric crenellated edged C{sub 6[3m(m-1)+1]}H{sub 6(2m-1)} (m = 2,..., 6) graphene hydrocarbon molecules

    Energy Technology Data Exchange (ETDEWEB)

    Philpott, Michael R., E-mail: philpott@imr.edu [Center for Computational Materials Science, Institute of Materials Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai (Japan); Kawazoe, Yoshiyuki [Center for Computational Materials Science, Institute of Materials Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, 980-8577 Sendai (Japan)

    2009-03-30

    Ab initio plane wave all valence electron based DFT calculations were used to explore the dichotomy of perimeter vs. interior in the electronic and geometric structure of the D{sub 6h} singlet ground state and D{sub 2h} lowest triplet state of planar graphene hydrocarbon molecules with crenellated (arm chair) edges and the general formula C{sub 6[3m(m-1)+1]} H{sub 6(2m-1)} where m = 2,...,6. The largest molecule C{sub 546}H{sub 66} was 4.78 nm across and contained 2250 valence electrons. These molecules are nominally 'fully benzenoid hydrocarbons'. However with increasing size, the core of central atoms abandoned any fully benzenoid geometry they had in small systems and organized into single layer graphite (graphene) structure. The perimeter atoms of the crenellation adopted a conjugated geometry with unequal bonds and between core and perimeter there were some C{sub 6} rings retaining remnants of aromatic sextet-type properties. Compared to a zigzag edge the crenellated edge conferred stability in all the systems studied as measured by the singlet homo-lumo level gap BG{sub 0} and the singlet-lowest triplet energy gap {Delta}E{sub ST}. For the largest crenellated system (m = 6) BG{sub 0} and {Delta}E{sub ST} were approximately 0.7 eV, larger in value than for similarly sized hexagonal graphenes with zigzag edges. Triplet states were identified for all the molecules in the series and in the case of the m = 2 molecule hexabenzocoronene C{sub 42}H{sub 18}, two conformations with D{sub 2h} symmetry were identified and compared to features on the triplet state potential energy surface of benzene.

  12. Glucose oxidase-graphene-chitosan modified electrode for direct electrochemistry and glucose sensing

    International Nuclear Information System (INIS)

    Kang, Xinhuang; Wang, Jun; Wu, Hong; Aksay, Ilhan A.; Liu, Jun; Lin, Yuehe

    2009-01-01

    Direct electrochemistry of a glucose oxidase (GOD)/graphene/chitosan nanocomposite was studied. The immobilized enzyme retains its bioactivity, exhibits a surface confined, reversible two-proton and two-electron transfer reaction, and has good stability, activity and a fast heterogeneous electron transfer rate with the rate constant (k s ) of 2.83 s -1 . A much higher enzyme loading (1.12 x 10 -9 mol/cm 2 ) is obtained as compared to the bare glass carbon surface. This GOD/graphene/chitosan nanocomposite film can be used for sensitive detection of glucose. The biosensor exhibits a wider linearity range from 0.08 mM to 12 mM glucose with a detection limit of 0.02 mM and much higher sensitivity (37.93 (micro)A mM -1 cm -2 ) as compared with other nanostructured supports. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of graphene, and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes direct electron transfer between redox enzymes and the surface of electrodes.

  13. Ion Irradiation Experiments on the Murchison CM2 Carbonaceous Chondrite: Simulating Space Weathering of Primitive Asteroids

    Science.gov (United States)

    Keller, L. P.; Christoffersen, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Remote sensing observations show that space weathering processes affect all airless bodies in the Solar System to some degree. Sample analyses and lab experiments provide insights into the chemical, spectroscopic and mineralogic effects of space weathering and aid in the interpretation of remote- sensing data. For example, analyses of particles returned from the S-type asteroid Itokawa by the Hayabusa mission revealed that space-weathering on that body was dominated by interactions with the solar wind acting on LL ordinary chondrite-like materials [1, 2]. Understanding and predicting how the surface regoliths of primitive carbonaceous asteroids respond to space weathering processes is important for future sample return missions (Hayabusa 2 and OSIRIS-REx) that are targeting objects of this type. Here, we report the results of our preliminary ion irradiation experiments on a hydrated carbonaceous chondrite with emphasis on microstructural and infrared spectral changes.

  14. Coordinated Chemical and Isotopic Imaging of Bells (CM2) Meteorite Matrix

    Science.gov (United States)

    Clemett, S. J.; Messenger, S.; Naklamura-Messenger, K.; Thomas-Keprta, K. L.

    2014-01-01

    Meteoritic organic matter is a complex conglomeration of species formed in distinct environments and processes in circumstellar space, the interstellar medium, the Solar Nebula and asteroids. Consequently meteorites constitute a unique record of primordial organic chemical evolution. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is little information as to how these species are spatially distributed and their relationship to the host mineral matrix. The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (chemical mapping study of the Bells meteorite using a newly developed two-step laser mass spectrometer (mu-L(sup 2)MS) capable of measuring a broad range of organic compounds.

  15. The interval Shapley value of an M/M/1 service system

    Directory of Open Access Journals (Sweden)

    Cheng-Guo E

    2017-09-01

    Full Text Available Service systems and their cooperation are one of the most important and hot topics in management and information sciences. To design a reasonable allocation mechanism of service systems is the key issue in the cooperation of service systems. In this paper, we systematically introduce the interval Shapley value as cost allocation of cooperative interval games 〈N, V〉 arising from cooperation in a multi-server service system, and provide an explicit expression for the interval Shapley value of cooperative interval games 〈N, V〉. We construct an interval game 〈N, W〉 of a service system which shares the same value for the grand coalition with the original interval game, by using the characteristic function which is dominated by the function of the original interval game. Finally, we prove that the interval game 〈N, W〉 is concave, which means that the interval Shapley value of the interval game 〈N, W〉 is in the interval core of this interval game, and illustrate this conclusion by using numerical examples.

  16. Slowdown in the $M/M/1$ discriminatory processor-sharing queue

    NARCIS (Netherlands)

    Cheung, S.K.; Kim, Bara; Kim, Jeongsim

    2008-01-01

    We consider a queue with multiple K job classes, Poisson arrivals, and exponentially distributed required service times in which a single processor serves according to the discriminatory processor-sharing (DPS) discipline. For this queue, we obtain the first and second moments of the slowdown, which

  17. Deuteration of ammonia in the starless core Ophiuchus/H-MM1

    Science.gov (United States)

    Harju, J.; Daniel, F.; Sipilä, O.; Caselli, P.; Pineda, J. E.; Friesen, R. K.; Punanova, A.; Güsten, R.; Wiesenfeld, L.; Myers, P. C.; Faure, A.; Hily-Blant, P.; Rist, C.; Rosolowsky, E.; Schlemmer, S.; Shirley, Y. L.

    2017-04-01

    Context. Ammonia and its deuterated isotopologues probe physical conditions in dense molecular cloud cores. The time-dependence of deuterium fractionation and the relative abundances of different nuclear spin modifications are supposed to provide a means of determining the evolutionary stages of these objects. Aims: We aim to test the current understanding of spin-state chemistry of deuterated species by determining the abundances and spin ratios of NH2D, NHD2 and ND3 in a quiescent, dense cloud. Methods: Spectral lines of NH3, NH2D, NHD2, ND3 and N2D+ were observed towards a dense, starless core in Ophiuchus with the APEX, GBT and IRAM 30-m telescopes. The observations were interpreted using a gas-grain chemistry model combined with radiative transfer calculations. The chemistry model distinguishes between the different nuclear spin states of light hydrogen molecules, ammonia and their deuterated forms. Different desorption schemes can be considered. Results: High deuterium fractionation ratios with NH2D/NH3 0.4, NHD2/ NH2D 0.2 and ND3/ NHD2 0.06 are found in the core. The observed ortho/para ratios of NH2D and NHD2 are close to the corresponding nuclear spin statistical weights. The chemistry model can approximately reproduce the observed abundances, but consistently predicts too low ortho/para-NH2D, and too large ortho/para-NHD2 ratios. The longevity of N2H+ and NH3 in dense gas, which is prerequisite to their strong deuteration, can be attributed to the chemical inertia of N2 on grain surfaces. Conclusions: The discrepancies between the chemistry model and the observations are likely to be caused by the fact that the model assumes complete scrambling in principal gas-phase deuteration reactions of ammonia, which means that all the nuclei are mixed in reactive collisions. If, instead, these reactions occur through proton hop/hydrogen abstraction processes, statistical spin ratios are to be expected. The present results suggest that while the deuteration of ammonia changes with physical conditions and time, the nuclear spin ratios of ammonia isotopologues do not probe the evolutionary stage of a cloud. Based on observations carried out with The Atacama Pathfinder Experiment (APEX), the Robert C. Byrd Green Bank Telescope (GBT), and the IRAM 30 m Telescope. APEX is a collaboration between Max-Planck Institut für Radioastronomie (MPIfR), Onsala Space Observatory (OSO), and the European Southern Observatory (ESO). GBT is managed by the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  18. Design and Implementation of an M/M/1 Queuing Model Algorithm ...

    African Journals Online (AJOL)

    Remote Medical Monitoring is a component of telemedicine capable of monitoring ... model follows a Poisson distribution with parameter (β)t and a probability .... The probability of no(zero) arrival in the .... "A Problem of Standards of Service ".

  19. M/M/1 RETRIAL QUEUEING SYSTEM WITH VACATION INTERRUPTIONS UNDER PRE-EMPTIVE PRIORITY SERVICE

    Directory of Open Access Journals (Sweden)

    Muthu Ganapathi Subramanian Annasamy

    2010-10-01

    Full Text Available Consider a single server retrial queueing system with pre-emptive priority service and vacation interruptions in which customers arrive in a Poisson process with arrival rate λ1 for low priority customers and λ2 for high priority customers. Further it is assume that the service times follow an exponential distribution with parameters μ1 and μ2 for low and high priority customers respectively. The retrial is introduced for low priority customers only. The server goes for vacation after exhaustively completing the service to both types of customers.  The vacation rate follows an exponential distribution with parameter α. The concept of vacation interruption is used in this paper that is the server comes from the vacation into normal working condition without completing his vacation period subject to some conditions. Let k be the maximum number of waiting spaces for high priority customers in front of the service station. The high priority customers will be governed by the pre-emptive priority service. We assume that the access from orbit to the service facility is governed by the classical retrial policy. This model is solved by using Matrix geometric Technique. Numerical  study  have been done for Analysis of Mean number of low priority customers in the orbit (MNCO, Mean number of high priority customers in the queue(MPQL,Truncation level (OCUT,Probability of server free and Probabilities  of server busy with low and high priority customers and probability of server in vacation for various values of λ1 , λ2 , μ1 , μ2, α and σ  in elaborate manner and also various particular cases of  this model have been discussed.

  20. Redox hydrogel based bienzyme electrode for L-glutamate monitoring.

    Science.gov (United States)

    Belay, A; Collins, A; Ruzgas, T; Kissinger, P T; Gorton, L; Csöregi, E

    1999-02-01

    Amperometric bienzyme electrodes based on coupled L-glutamate oxidase (GlOx) and horseradish peroxidase (HRP) were constructed for the direct monitoring of L-glutamate in a flow injection (FI)-system. The bienzyme electrodes were constructed by coating solid graphite rods with a premixed solution containing GlOx and HRP crosslinked with a redox polymer formed of poly(1-vinylimidazole) complexed with (osmium (4-4'-dimethylbpy)2 Cl)II/III. Poly(ethylene glycol) diglycidyl ether (PEGDGE) was used as the crosslinker and the modified electrodes were inserted as the working electrode in a conventional three electrode flow through amperometric cell operated at -0.05 V versus Ag¿AgCl (0.1 M KCl). The bienzyme electrode was optimized with regard to wire composition, Os-loading of the wires, enzyme ratios, coating procedure, flow rate, effect of poly(ethyleneimine) addition, etc. The optimized electrodes were characterized by a sensitivity of 88.36 +/- 0.14 microA mM(-1) cm(-2), a detection limit of 0.3 microM (calculated as three times the signal-to-noise ratio), a response time of less than 10 s and responded linearly between 0.3 and 250 microM (linear regression coefficient = 0.999) with an operational stability of only 3% sensitivity loss during 8 h of continuous FI operation at a sample throughput of 30 injections h(-1).

  1. Operation of a Five-Stage 40,000-CM2-Area Insulator Stack at 158 KV/CM

    International Nuclear Information System (INIS)

    Anderson RA; Clark, Robert E; Corcoran, PA; Douglas, John W; Gilliland, TL; Horry, ML; Hughes, Thomas P; Ives, HC; Long, FW; Martin, TH; McDaniel, DH; Milton, Osborne; Mostrom, Michael A; Seamen, JF; Shoup, RW; Smith, ID; Smith, JW; Spielman, RB; Struve, KW; Stygar, WA; Vogtlin, George E; Wagoner, TC; Yamamoto, Osamu

    1999-01-01

    We have demonstrated successful operation of a 3.35- m-diameter insulator stack at 158 kV/cm on five consecutive Z-accelerator shots. The stack consisted of five +45 deg;-profile 5.715-cm-thick cross-linked-polystyrene (Rexolite- 1422) insulator rings, and four anodized- aluminum grading rings shaped to reduce the field at cathode triple junctions. The width of the voltage pulse at 89% of peak was 32 ns. We compare this result to a new empirical flashover relation developed from previous small-insulator experiments conducted with flat unanodized electrodes. The relation predicts a 50% flashover probability for a Rexolite insulator during an applied voltage pulse when E max e -0.27/d (t eff C) 1/10 = 224, where E max is the peak mean electric field (kV/cm), d is the insulator thickness (cm), t eff is the effective pulse width (ps), and C is the insulator circumference (cm). We find the Z stack can be operated at a stress at least 19% higher than predicted. This result, and previous experiments conducted by Vogtlin, suggest anodized electrodes with geometries that reduce the field at both anode and cathode triple junctions would improve the flashover strength of +45 deg; insulators

  2. The 40x40cm2 gaseous microstrip detector Micromegas for the high-luminosity COMPASS experiment at CERN

    International Nuclear Information System (INIS)

    Bernet, C.; Abbon, P.; Ball, J.; Bedfer, Y.; Delagnes, E.; Giganon, A.; Kunne, F.; Le Goff, J.-M.; Magnon, A.; Marchand, C.; Neyret, D.; Panebianco, S.; Pereira, H.; Platchkov, S.; Procureur, S.; Rebourgeard, P.; Tarte, G.; Thers, D.

    2005-01-01

    The measurements in the COMPASS experiment at CERN require high-resolution tracking detectors, with low radiation length and high-rate capability. For this purpose we have developed and optimized a gaseous microstrip detector 'Micromegas'. Twelve planes with 1024 strips each, assembled in 3 stations of 4 views XYUV, are now being operated with success in the COMPASS environment. We describe here the performances and results obtained

  3. Scintillation hodoscope with 50x50 cm2 sensitive area on the basis of hodoscopic FEhU's

    International Nuclear Information System (INIS)

    Borog, V.V.; Dronov, V.V.; Vasil'chenko, V.G.; Rykalin, V.I.; Demekhin, A.B.

    1986-01-01

    The problems of choosing optimal constructions of sensitive elements of large hodoscopes on the base of hodoscopic photamultipliers are considered. The obtained results of numerical calculations for choosing optimal constructions and materials of hodoscope elements are confirmed by the results of the performed measurements. The measured spatial resolution of one of constructions of scintillation hodoscopes with the 50x50x2 cm 3 sensitive volume using two hodoscopic photomultipliers constituted ±3 mm

  4. Amplification and focusing of a picosecond chirped pulse to 20TW and 5x1017W/cm2

    International Nuclear Information System (INIS)

    Sauteret, C.; Husson, D.; Rouyer, C.; Seznec, S.; Gary, S.

    1991-01-01

    Pulses of 20 TW power have been generated at 1064 nm using the Chirped Pulse Amplification technique coupled to a 90 mm output aperture powerful Nd:silicate glass amplification line. This system delivers 60 J in a chirped pulse of 600 ps duration with a capacity of maintaining 3.5 nm output bandwidth. These chirped pulses have been compressed to 1.2 ps with an energy of 24J using large holographic diffraction gratings. After presenting the results we discuss the expected applications in atomic and plasma physics

  5. Laser guiding at>1018 W/cm2 in plasma channels formed by the ignitor heater method

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, C.; vanTilborg, J.; Leemans, W.P.

    2004-01-01

    Experiments explore guiding of intense laser pulses, optimization using channel formation beams and gas jet targets, and the interplay of channel guiding and relativistic self guiding. Impact on laser wakefield particle acceleration is being assessed

  6. Transient Analysis of an M/M/1 queue with Multiple Exponential Vacation and N-Policy

    Directory of Open Access Journals (Sweden)

    Vijayashree KV

    2015-12-01

    Full Text Available A single server Markovian queueing model is considered.  The arrivals are allowed to join the queue according to a Poisson distribution and the service takes place according to an exponential distribution.  Whenever the system is empty, the server goes for a vacation and return back to the system after N or more customers are found in the system. If the number of customers in the system is less than ‘’ then the server takes another vacation.  In this paper, we obtain explicit expressions for the time dependent system size probabilities of such a model using Laplace transform and generating function techniques.  Numerical illustrations are added to support the theoretical results obtained.

  7. Space charge distributions in glass fibre/epoxy resin composites under dc 10 kV mm-1 electric field

    International Nuclear Information System (INIS)

    Tanaka, Hidesato; Ohki, Yoshimichi; Fukunaga, Kaori; Maeno, Takashi; Okamoto, Kenji

    2007-01-01

    In this paper, the authors discuss one- and three-dimensional space charge distributions in glass fibre/epoxy resin composites. By the conventional pulsed electroacoustic (PEA) method, only a one-dimensional distribution of the average charge over a whole area parallel to the two electrodes can be observed. Therefore, the authors have developed a new PEA system capable of measuring a three-dimensional space charge distribution. Using this system, they measured the charge distribution in glass fibre/epoxy resin composites made of lattice-woven glass fibre and epoxy resin. It has become clear that spatial variation in signal intensity observed depends on the internal structure of the composite. There appear repetitious positions where a high charge density is observed on the same lateral cross section along the vertical direction in the composite. Such positions are consistent with the intersections of the glass fibres. Accumulation of mobile charge carriers or appearance of polarization charge due to mismatch of the ratio of the conductivity and permittivity between the glass fibre and the epoxy resin is thought to be responsible for the PEA signals

  8. Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

    Science.gov (United States)

    Guan, Dongsheng; Cai, Chuan; Wang, Ying

    2011-04-01

    We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

  9. [Photovoltaic character of organic EL devices MEH-PPV/Alq3].

    Science.gov (United States)

    Lin, Peng; Liang, Chun-Jun; Deng, Zhen-Bo; Xiong, De-Ping; Wang, Li; Zhang, Zhi-Feng; Zhang, Xi-Qing

    2005-01-01

    An organic photovoltaic(PV) cell, ITO/MEH-PPV/Alq3/LiF/Al, was fabricated. The MEH-PPV and Alq3 are the electron-acceptor and donor in the cell, respectively. The respond region matchs the adsorption of Alq3 film. Under UV light with 0.5 mW x cm(-2), the cell shows a short-circuit current of 2.4 microA x cm(-2), open-circuit voltage of 2.6 V, a fill factor of 0.71, and a power conversion efficiency of 0.9%. It was found that the PV cell indicates electroluminescence (EL) performance and could emit orange light at DC voltage. The maximum luminance is about 1 000 cd x cm(-2) at 15 V.

  10. Uranium mobility during interaction of rhyolitic obsidian, perlite and felsite with alkaline carbonate solution: T = 120° C, P = 210 kg/cm2

    Science.gov (United States)

    Zielinski, Robert A.

    1979-01-01

    Well-characterized samples of rhyolitic obsidian, perlite and felsite from a single lava flow are leached of U by alkaline oxidizing solutions under open-system conditions. Pressure, temperature, flow rate and solution composition are held constant in order to evaluate the relative importance of differences in surface area and crystallinity. Under the experimental conditions U removal from crushed glassy samples proceeds by a mechanism of glass dissolution in which U and silica are dissolved in approximately equal weight fractions. The rate of U removal from crushed glassy samples increases with decreasing average grain size (surface area). Initial rapid loss of a small component (≈ 2.5%) of the total U from crushed felsite. followed by much slower U loss, reflects variable rates of attack of numerous uranium sites. The fractions of U removed during the experiment ranged from 3.2% (felsite) to 27% (perlite). An empirical method for evaluating the relative rate of U loss from contemporaneous volcanic rocks is presented which incorporates leaching results and rock permeability data.

  11. Mineralogy and Textural Characteristics of Fine-grained Rims in the Yamato 791198 CM2 Carbonaceous Chondrite: Constraints on the Location of Aqueous Alteration

    Science.gov (United States)

    Chizmadia, Lysa J.; Brearley, Adrian J.

    2003-01-01

    Carbonaceous chondrites provide important clues into the nature of physical and chemical processes in the early solar system. A question of key importance concerns the role of water in solar nebular and asteroidal processes. The effects of water on primary mineral assemblages have been widely recognized in chondritic meteorites, especially the CI and CM carbonaceous chondrites. These meteorites have undergone extensive aqueous alteration that occurred prior to their arrival on Earth. In the case of the CM chondrites, this alteration has resulted in the partial to complete replacement of the primary nebular phases with secondary alteration phases. Considerable controversy exists as to the exact location where the alteration of the CM chondrites occurred. Several textural lines of evidence have been cited in support of aqueous alteration prior to the accretion of the final parent asteroid. An important line of evidence to support this hypothesis is the dis-equilibrium nature of fine-grained rims and matrix materials. [2] also noted the juxtaposition of micron-sized Fe-Ni metal grains and apparently unaltered chondrule glass against hydrated rim silicates. Conversely, there is a large body of evidence in favor of parent body alteration such as the occurrence of undisturbed Fe-rich aureoles and the systematic redistribution of elemental components over millimeters, e.g., Mg(+2) into the matrix and Fe(+2) into chondrules etc.

  12. Laser-driven ablation through fast electrons in PALS experiment at the laser radiation intensity of 1–50 PW/cm2

    Czech Academy of Sciences Publication Activity Database

    Gus’kov, S.Yu.; Demchenko, N. N.; Kasperczuk, A.; Pisarczyk, T.; Kalinowska, Z.; Chodukowski, T.; Renner, Oldřich; Šmíd, Michal; Krouský, Eduard; Pfeifer, Miroslav; Skála, Jiří; Ullschmied, Jiří; Pisarczyk, P.

    2014-01-01

    Roč. 32, č. 1 (2014), s. 177-195 ISSN 0263-0346 R&D Projects: GA MŠk LM2010014; GA MŠk EE2.3.20.0279 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant - others:AVČR(CZ) M100101208; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : inertial confinement fusion * shock ignition * laser-produced plasma * three-frame interferometry * X-ray spectroscopy * fast electron generation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.295, year: 2014

  13. An analysis of the static load test on single square pile of 40x40 cm2, using finite element method in Rusunawa project, Jatinegara, Jakarta

    Science.gov (United States)

    Harasid, Harun; Roesyanto; Iskandar, Rudi; Silalahi, Sofyan A.

    2018-03-01

    Piling Foundation is one of the foundations which is used to penetrate its load through soil layer. The power carried by the piling is obtained from the end bearing capacity, that is, the compressive end piling and friction bearing capacity obtained from friction bearing and adhesive capacity between the piling and the soil around it. The investigation on the Standard Penetration Test is aimed to get the description of soil layer, based on the type and color of soil through visual observation, and soil characteristics. SPT data can be used to calculate bearing capacity. Besides investigating the SPT, this study is also been equipped by taking the samples in laboratory and loading test on the piling and Ducth Cone Penetrometer (DCP) data to confirm its bearing capacity. This study analyzed bearing capacity and settlement in the square pile of 40X40 cm in diameter in a single pile or grouped, using an empirical method, AllPile program, Plaxis program, and comparing the result with interpreting its loading test in the foundation of Rusunawa project, Jatinegara, Jakarta. The analysis was been done by using the data on soil investigation and laboratory by comparing them with Mohr-Coulomb soil model. Ultimate bearing capacity from the SPT data in the piling of 15.4 meters was 189.81 tons and the parameter of soil shear strength was 198.67 tons. The sander point, based on Aoki and De Alencar bearing capacity was 276.241 tons and based on Mayerhoff it was 305.49 tons. Based on the loading test of bearing capacity, unlimited bearing capacity for the three methods was Davisson (260 tons), Mazurkiewich (270 tons), and Chin (250 tons). The efficiency of grouped piles according to Converse-Library Equation method = 0.73, according to Los Angeles Group Action Equation method = 0.59, and according to Sheila-Keeny method = 0.94. Bearing capacity based on piling strength was 221.76 tons, bearing capacity based on calendaring data was 201.71 tons, and lateral bearing capacity of a single piling foundation was 129.6 kN (12.96 tons). When the maximum load (280 tons) was been given, more decrease occurred in the Maintained load test of 21.00 mm and Quick Load Test method of 20.67 mm, compared with the result of Load Test in the field of 18.74 mm. Based on ASTM D1143/81, the permitted value was 25.40 mm. Therefore, based on that decreasing, it could be concluded that foundation piles were safe in the construction. The pore water pressure is highly influenced by time so that in Maintained Load Test and Quick Load Test, there was the disparity in the level of pore water pressure. Based on the result of the calculation, Quick Load Test showed that in pore water pressure was dissipated in its acceleration.

  14. Fe isotope composition of bulk chondrules from Murchison (CM2): Constraints for parent body alteration, nebula processes and chondrule-matrix complementarity

    Science.gov (United States)

    Hezel, Dominik C.; Wilden, Johanna S.; Becker, Daniel; Steinbach, Sonja; Wombacher, Frank; Harak, Markus

    2018-05-01

    Chondrules are a major constituent of primitive meteorites. The formation of chondrules is one of the most elusive problems in cosmochemistry. We use Fe isotope compositions of chondrules and bulk chondrites to constrain the conditions of chondrule formation. Iron isotope compositions of bulk chondrules are so far only known from few studies on CV and some ordinary chondrites. We studied 37 chondrules from the CM chondrite Murchison. This is particularly challenging, as CM chondrites contain the smallest chondrules of all chondrite groups, except for CH chondrites. Bulk chondrules have δ56Fe between -0.62 and +0.24‰ relative to the IRMM-014 standard. Bulk Murchison has as all chondrites a δ56Fe of 0.00‰ within error. The δ56Fe distribution of the Murchison chondrule population is continuous and close to normal. The width of the δ56Fe distribution is narrower than that of the Allende chondrule population. Opaque modal abundances in Murchison chondrules is in about 67% of the chondrules close to 0 vol.%, and in 33% typically up to 6.5 vol.%. Chondrule Al/Mg and Fe/Mg ratios are sub-chondritic, while bulk Murchison has chondritic ratios. We suggest that the variable bulk chondrule Fe isotope compositions were established during evaporation and recondensation prior to accretion in the Murchison parent body. This range in isotope composition was likely reduced during aqueous alteration on the parent body. Murchison has a chondritic Fe isotope composition and a number of chondritic element ratios. Chondrules, however, have variable Fe isotope compositions and chondrules and matrix have complementary Al/Mg and Fe/Mg ratios. In combination, this supports the idea that chondrules and matrix formed from a single reservoir and were then accreted in the parent body. The formation in a single region also explains the compositional distribution of the chondrule population in Murchison.

  15. Establishment of dosimetric references for high energy X-ray beams of very small field sizes (≤ 1 cm2) used in radiotherapy

    International Nuclear Information System (INIS)

    Dufreneix, Stephane

    2014-01-01

    The French primary standard dosimetry laboratory 'Laboratoire National Henri Becquerel' is in charge of the establishment of dosimetric standards for ionizing radiation beams. Absolute dose measurements are thus available for X-Ray beams used in radiotherapy for field sizes between 10 and 2 cm. Since the miniaturization of absolute dosimeters is not possible for smaller field sizes, a dose area product (DAP) has been suggested as a substitute to the absorbed dose at a point.In order to measure a DAP with dosimeters which sensitive surface is larger than the beam, a graphite calorimeter with a sensitive surface of 3 cm diameter was designed, built and tested. An ionization chamber with the same diameter was realized and tested to transfer the dosimetric references to the end users. Its calibration factor in terms of DAP was determined in circular beams of 2, 1 and 0.75 cm diameter with an uncertainty smaller than 0.7 %. The two-Dimension relative dose distribution was measured thanks to a diamond dosimeter, a PinPoint ionization chamber and gafchromic films, using a specific protocol. Both approaches, respectively based on a PDS and an absorbed dose to water at a point, were in good agreement in the 2 cm beam. Correction factors determined from Monte Carlo simulations and measured dose distributions were needed for this comparison. The calibration factor of the large ionization chamber in the 1 and 0.75 cm diameter beams were in good agreement within the uncertainties but a gap of -2.6 % was found with the one established in the 2 cm diameter beam. As a result, the DAP can be used if the sensitive surface is much larger than the beam section. (author) [fr

  16. Characterization of Thin Pixel Sensor Modules Interconnected with SLID Technology Irradiated to a Fluence of 2$\\cdot 10^{15}$\\,n$_{\\mathrm{eq}}$/cm$^2$

    CERN Document Server

    INSPIRE-00237859; Beimforde, M.; Macchiolo, A.; Moser, H.G.; Nisius, R.; Richter, R.H.

    2011-01-01

    A new module concept for future ATLAS pixel detector upgrades is presented, where thin n-in-p silicon sensors are connected to the front-end chip exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the signals are read out via Inter Chip Vias (ICV) etched through the front-end. This should serve as a proof of principle for future four-side buttable pixel assemblies for the ATLAS upgrades, without the cantilever presently needed in the chip for the wire bonding. The SLID interconnection, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It is characterized by a very thin eutectic Cu-Sn alloy and allows for stacking of different layers of chips on top of the first one, without destroying the pre-existing bonds. This paves the way for vertical integration technologies. Results of the characterization of the first pixel modules interconnected through SLID as well as of one sample irradiated to $2\\cdot10^{15}$\\,\

  17. Characterization of Thin Pixel Sensor Modules Interconnected with SLID Technology Irradiated to a Fluence of 2⋅10 15 $n_{eq}$ /cm 2

    CERN Document Server

    Weigell, P; Beimforde, M; Macchiolo, A; Moser, H G; Nisius, R; Richter, R H

    2011-01-01

    A new module concept for future ATLAS pixel detector upgrades is presented, where thin n-in-p silicon sensors are connected to the front-end chip exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the signals are read out via Inter Chip Vias (ICV) etched through the front-end. This should serve as a proof of principle for future four-side buttable pixel assemblies for the ATLAS upgrades, without the cantilever presently needed in the chip for the wire bonding. The SLID interconnection, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It is characterized by a very thin eutectic Cu-Sn alloy and allows for stacking of different layers of chips on top of the first one, without destroying the pre-existing bonds. This paves the way for vertical integration technologies. Results of the characterization of the first pixel modules interconnected through SLID as well as of one sample irradiated to 2⋅10 15 \\,\

  18. Performance of p-type micro-strip detectors after irradiation to $7.5x10^{15} p/cm^{2}$

    CERN Document Server

    Allport, Philip P; Lozano-Fantoba, Manuel; Sutcliffe, Peter; Velthuis, J J; Vossebeld, Joost Herman

    2004-01-01

    Exploiting the advantages of reading out segmented silicon from the n-side, we have produced test detectors with LHC pitch but 1 cm long strips which even after proton irradiation at the CERN PS to 7.5*10 /sup 15/ cm/sup -2/ show signal to noise greater than 8:1 using LHC speed electronics. This dose exceeds by a factor of 2 that required for a replacement of the ATLAS semiconductor tracker to cope with an upgrade of the LHC to a Super-LHC with 10 times greater luminosity. These detectors were processed on p-type starting material of resistivity ~ 2 k Omega cm and, unlike n-in-n designs, only required single-sided processing. Such technology should therefore provide a relatively inexpensive route to replacing the central tracking at both ATLAS and CMS for Super-LHC. The shorter strip length is required to limit the noise. Even at these extreme doses 30% of the non-irradiated signal is seen. This 7000e/sup -/ signal (in 280 mu m thick sensors) is very competitive with the post irradiation performance of other,...

  19. Optimal control of M/M/1 two-phase queueing system with state-dependent arrival rate, server breakdowns, delayed repair, and N-policy

    Science.gov (United States)

    Rao, Hanumantha; Kumar, Vasanta; Srinivasa Rao, T.; Srinivasa Kumar, B.

    2018-04-01

    In this paper, we examine a two-stage queueing system where the arrivals are Poisson with rate depends on the condition of the server to be specific: vacation, pre-service, operational or breakdown state. The service station is liable to breakdowns and deferral in repair because of non-accessibility of the repair facility. The service is in two basic stages, the first being bulk service to every one of the customers holding up on the line and the second stage is individual to each of them. The server works under N-policy. The server needs preliminary time (startup time) to begin batch service after a vacation period. Startup times, uninterrupted service times, the length of each vacation period, delay times and service times follows an exponential distribution. The closed form of expressions for the mean system size at different conditions of the server is determined. Numerical investigations are directed to concentrate the impact of the system parameters on the ideal limit N and the minimum base expected unit cost.

  20. A High-Intensity, RF Plasma-Sputter Negative Ion Source

    International Nuclear Information System (INIS)

    Alton, G.D.; Bao, Y.; Cui, B.; Lohwasser, R.; Reed, C.A.; Zhang, T.

    1999-01-01

    A high-intensity, plasma-sputter negative-ion source based on the use of RF power for plasma generation has been developed that can be operated in either pulsed or dc modes. The source utilizes a high-Q, self-igniting, inductively coupled antenna system, operating at 80 MHz that has been optimized to generate Cs-seeded plasmas at low pressures (typically, - (610 microA); F - (100 microA); Si - (500 microA); S - (500 microA); P - (125 microA); Cl - (200 microA); Ni - (150 microA); Cu - (230 microA); Ge - (125 microA); As - (100 microA); Se - (200 microA); Ag - (70 microA); Pt - (125 microA); Au - (250 microA). The normalized emittance var e psilon n of the source at the 80% contour is: var e psilon n = 7.5 mm.mrad.(MeV) 1/2 . The design principles of the source, operational parameters, ion optics, emittance and intensities for a number of negative-ion species will be presented in this report

  1. Evidence for a Na+/Ca2+ exchange mechanism in frog skin epithelium

    DEFF Research Database (Denmark)

    Madsen, K H; Brodin, Birger; Nielsen, R

    1999-01-01

    In the present study we investigated the possible existence of a Na+/Ca2+ exchange mechanism in the basolateral membrane of the frog skin epithelium and whether such a mechanism plays a role in the regulation of transepithelial Na+ transport. Cytosolic calcium ([Ca2+]i) was measured with the probe...... in serosal Na+ were followed by stepwise changes in [Ca2+]i. These observations indicate the existence of a Na+/Ca2+ exchange mechanism in the basolateral membrane of the frog skin epithelium. The transepithelial Na+ transport decreased from 13.2+/-1.8 to 9.2+/-1.5 microA cm-2 (n=8, P=0.049) when Na...

  2. Observation and analysis of cosmic electromagnetic cascades detected in lead photoemulsion chamber of the Brazil-Japan cooperation, exposed in Monte Chacaltaya, Bolivia (altitude 5200m, air pressure 550 gr.cm-2)

    International Nuclear Information System (INIS)

    Bastos, C.A.

    1971-04-01

    The cosmic gamma radiations in the photoemulsion chamber for Brazil-Japan Cooperation are studied. These radiations reproduces the electromagnetic component of extensive air showers at the begining of its development through the atmosphere. The gamma radiations, which is 0 Π meson decay products emitted in nuclear interaction, are detected by electromagnetic cascades which are developed when they reach the photoemulsion chamber. Cosmic gamma radiations is a set of parallel electromagnetic cascades proceeding from nuclear interactions. The information about high energy nuclear interactions making possible to study the structure of extensive air showers at the beginning of its development and multiple meson production are obtained. (M.C.K.) [pt

  3. Hybrid complementary circuits based on p-channel organic and n-channel metal oxide transistors with balanced carrier mobilities of up to 10 cm2/Vs

    KAUST Repository

    Isakov, Ivan

    2016-12-29

    We report the development of hybrid complementary inverters based on p-channel organic and n-channel metal oxide thin-film transistors (TFTs) both processed from solution at <200 °C. For the organic TFTs, a ternary blend consisting of the small-molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, the polymer indacenodithiophene-benzothiadiazole (CIDT-BT) and the p-type dopant CF was employed, whereas the isotype InO/ZnO heterojunction was used for the n-channel TFTs. When integrated on the same substrate, p- and n-channel devices exhibited balanced carrier mobilities up to 10 cm/Vs. Hybrid complementary inverters based on these devices show high signal gain (>30 V/V) and wide noise margins (70%). The moderate processing temperatures employed and the achieved level of device performance highlight the tremendous potential of the technology for application in the emerging sector of large-area microelectronics.

  4. Hybrid complementary circuits based on p-channel organic and n-channel metal oxide transistors with balanced carrier mobilities of up to 10 cm2/Vs

    KAUST Repository

    Isakov, Ivan; Paterson, Alexandra F.; Solomeshch, Olga; Tessler, Nir; Zhang, Qiang; Li, Jun; Zhang, Xixiang; Fei, Zhuping; Heeney, Martin; Anthopoulos, Thomas D.

    2016-01-01

    We report the development of hybrid complementary inverters based on p-channel organic and n-channel metal oxide thin-film transistors (TFTs) both processed from solution at <200 °C. For the organic TFTs, a ternary blend consisting of the small-molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene, the polymer indacenodithiophene-benzothiadiazole (CIDT-BT) and the p-type dopant CF was employed, whereas the isotype InO/ZnO heterojunction was used for the n-channel TFTs. When integrated on the same substrate, p- and n-channel devices exhibited balanced carrier mobilities up to 10 cm/Vs. Hybrid complementary inverters based on these devices show high signal gain (>30 V/V) and wide noise margins (70%). The moderate processing temperatures employed and the achieved level of device performance highlight the tremendous potential of the technology for application in the emerging sector of large-area microelectronics.

  5. Electrophysiological study of transport systems in isolated perfused pancreatic ducts: properties of the basolateral membrane

    DEFF Research Database (Denmark)

    Novak, I; Greger, R

    1988-01-01

    - concentration from 0 to 25 mmol/l produced fast and sustained depolarization of PDbl by 8.5 +/- 1.0 mV (n = 149). It was investigated whether the effect of HCO3- was due to a Na+-dependent transport mechanism on the basolateral membrane, where the ion complex transferred into the cell would be positively...... was monitored by electrophysiological techniques. In this report some properties of the basolateral membrane of pancreatic duct cells are described. The transepithelial potential difference (PDte) in ducts bathed in HCO3(-)-free and HCO3(-)-containing solution was -0.8 and -2.6 mV, respectively. The equivalent...... short circuit current (Isc) under similar conditions was 26 and 50 microA . cm-2. The specific transepithelial resistance (Rte) was 88 omega cm2. In control solutions the PD across the basolateral membrane (PDbl) was -63 +/- 1 mV (n = 314). Ouabain (3 mmol/l) depolarized PDbl by 4.8 +/- 1.1 mV (n = 6...

  6. NH4+ secretion in the avian colon. An actively regulated barrier to ammonium permeation of the colon mucosa

    DEFF Research Database (Denmark)

    Holtug, K.; Laverty, G.; Arnason, S.S.

    2009-01-01

    Experiments were designed to characterize an active, electrogenic transport of NH(4)(+) ions across the colonic epithelium of the domestic fowl (Gallus gallus). Colonic segments were isolated and stripped of underlying muscle. The mucosal epithelia were mounted in Ussing chambers and voltage......-clamped to measure the short-circuit currents (I(SC)) associated with transport. Bilateral addition of NH(4)(+) caused a dose-dependent outward current (negative I(SC)), with a Km of 34+/-8 mM and a maximal current response of 311+/-47 microA cm(-2) (12+/-2 microEq cm(-2) h(-1)). A similar effect was seen...... with unilateral addition of NH(4)(+) to the serosal (s) side, but not with mucosal (m) addition. Pre-treatment with 10(-4) M amiloride exposed a net outward (negative) I(SC), and serosal NH(4)(+) addition further increased this outward current with a Km of 53+/-24 mM. Decreasing the bath pH from 7.3 to 6.0 did...

  7. Nanomaterial-based Electrochemical Sensors for the Detection of Glucose and Cholesterol

    Science.gov (United States)

    Ahmadalinezhad, Asieh

    properties, we fabricated a highly sensitive and mediator-free electrochemical biosensor for the determination of total cholesterol. The developed biosensor possessed high selectivity and sensitivity (29.33 microA mM--1cm --2). The apparent Michaelis--Menten constant, KappM of this biosensor was very low (0.64 mM), which originated from both the effective immobilization process and the nanoporous structure of the substrate. The biosensor exhibited a wide linear range, up to 300 mg dL--1 , in a physiological environment (pH 7.4); making it a promising candidate for the clinical determination of cholesterol. The fabricated biosensor was tested further by utilizing actual food samples (e.g., margarine, butter and fish oil). The results indicated that it has the potential capacity to be employed as a facile cholesterol detection tool in the food industry and for supplement quality control. To enhance the stability of the biosensors in the continuous monitoring of glucose, we designed a novel platform that was based on buckypaper. The fabricated biosensor responded to glucose with a considerable functional lifetime of over 80 days and detected glucose with a dynamic linear range of over 9 mM with a detection limit of 0.01 mM. To investigate the effects of the physical dimensions of nanomaterials on electrochemical biosensing, we synthesized TiO2 nanowires with controllable dimensions via a facile thermal oxidation treatment of a Ti substrate. To improve the conductivity of the TiO2 nanowires and to facilitate the immobilization of enzymes, a thin layer of carbon was deposited onto the TiO2 nanowires via a chemical vapour deposition method. Upon the immobilization of glucose oxidase as a model protein, direct electron transfer was observed in a mediator-free biosensing environment. Our electrochemical studies have revealed that the electron transfer rate of the immobilized glucose oxidase is strongly dependent on the dimensions of the carbonized TiO 2 nanowires, and that the

  8. A pixel segmented silicon strip detector for ultra fast shaping at low noise and low power consumption

    International Nuclear Information System (INIS)

    Misiakos, K.; Kavadias, S.

    1996-01-01

    A new radiation imaging device is proposed based on strips segmented into small pixels. Every pixel contains a submicron transistor that is normally biased in weak inversion. The ionization charge, upon collection by the pixel, changes the bias of the transistor to strong inversion and supplies a current up to several tens of a microA. This is a consequence of the small pixel capacitance (12 fF). The drains and sources of the transistors on the same row and column are shorted to bus lines that effectively become the Y and X coordinates. These bus lines are connected to the off chip ICON amplifiers to provide a 10 ns peaking time at a noise of about 150 electrons and 1 nW power consumption, for a 10x10 cm 2 detector and a MIP excitation. The noise performance is dominated by the ICON transistors. The cross talk between adjacent strips can be kept at a few percentage points provided a low transistor bias current is used

  9. Facile and controllable preparation of glucose biosensor based on Prussian blue nanoparticles hybrid composites.

    Science.gov (United States)

    Li, Lei; Sheng, Qinglin; Zheng, Jianbin; Zhang, Hongfang

    2008-11-01

    A glucose biosensor based on polyvinylpyrrolidone (PVP) protected Prussian blue nanoparticles (PBNPs)-polyaniline/multi-walled carbon nanotubes hybrid composites was fabricated by electrochemical method. A novel route for PBNPs preparation was applied in the fabrication with the help of PVP, and from scanning electron microscope images, Prussian blue particles on the electrode were found nanoscaled. The biosensor exhibits fast current response (<6 s) and a linearity in the range from 6.7x10(-6) to 1.9x10(-3) M with a high sensitivity of 6.28 microA mM(-1) and a detection limit of 6x10(-7) M (S/N=3) for the detection of glucose. The apparent activation energy of enzyme-catalyzed reaction and the apparent Michaelis-Menten constant are 23.9 kJ mol(-1) and 1.9 mM respectively, which suggests a high affinity of the enzyme-substrate. This easy and controllable construction method of glucose biosensor combines the characteristics of the components of the hybrid composites, which favors the fast and sensitive detection of glucose with improved analytical capabilities. In addition, the biosensor was examined in human serum samples for glucose determination with a recovery between 95.0 and 104.5%.

  10. A high-resolution atlas of the infrared spectrum of the Sun and the Earth atmosphere from space: A compilation of ATMOS spectra of the region from 650 to 4800 cm (2.3 to 16 micron). Volume 1: The Sun

    Science.gov (United States)

    Farmer, Crofton B.; Norton, Robert H.

    1989-01-01

    During the period April 29 through May 2, 1985, the Atmospheric Trace Molecular Spectroscopy experiment was operated as part of the Spacelab-3 payload of the shuttle Challenger. The instrument, a modified Michelson Interferometer covering the frequency range from 600 to 5000/cm, at a spectral resolution of 0.01/cm, recorded infrared spectra of the Sun and of the Earth's atmosphere at times close to entry into and exit from occultation by the Earth's limb as seen from the shuttle orbit of 360 km. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., solar pure spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas, believed to be the first record of observations of the continuous high resolution infrared spectrum of the Sun and the Earth's atmosphere from space, provides a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes; the data are also available in digital form.

  11. THE MASSIVE PROTOSTELLAR CLUSTER NGC 6334I AT 220 au RESOLUTION: DISCOVERY OF FURTHER MULTIPLICITY, DIVERSITY, AND A HOT MULTI-CORE

    Energy Technology Data Exchange (ETDEWEB)

    Brogan, C. L.; Hunter, T. R.; Indebetouw, R. [NRAO, 520 Edgemont Rd, Charlottesville, VA 22903 (United States); Cyganowski, C. J. [SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom); Chandler, C. J. [NRAO, P.O. Box 0, Socorro, NM 87801 (United States); Friesen, R., E-mail: cbrogan@nrao.edu [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H4 (Canada)

    2016-12-01

    We present Very Large Array and Atacama Large Millimeter/submillimeter Array imaging of the deeply embedded protostellar cluster NGC 6334I from 5 cm to 1.3 mm at angular resolutions as fine as 0.″17 (220 au). The dominant hot core MM1 is resolved into seven components at 1.3 mm, clustered within a radius of 1000 au. Four of the components have brightness temperatures >200 K, radii ∼300 au, minimum luminosities ∼10{sup 4} L {sub ⊙}, and must be centrally heated. We term this new phenomenon a “hot multi-core.” Two of these objects also exhibit compact free–free emission at longer wavelengths, consistent with a hypercompact H ii region (MM1B) and a jet (MM1D). The spatial kinematics of the water maser emission centered on MM1D are consistent with it being the origin of the high-velocity bipolar molecular outflow seen in CO. The close proximity of MM1B and MM1D (440 au) suggests a proto-binary or a transient bound system. Several components of MM1 exhibit steep millimeter spectral energy distributions indicative of either unusual dust spectral properties or time variability. In addition to resolving MM1 and the other hot core (MM2) into multiple components, we detect five new millimeter and two new centimeter sources. Water masers are detected for the first time toward MM4A, confirming its membership in the protocluster. With a 1.3 mm brightness temperature of 97 K coupled with a lack of thermal molecular line emission, MM4A appears to be a highly optically thick 240  L {sub ⊙} dust core, possibly tracing a transient stage of massive protostellar evolution. The nature of the strongest water maser source CM2 remains unclear due to its combination of non-thermal radio continuum and lack of dust emission.

  12. THE ESTIMATION OF CARCASS TRAITS OF BALI BULLS USING ULTRASOUND

    Directory of Open Access Journals (Sweden)

    A.B. Sri Rachma

    2014-10-01

    Full Text Available A study was conducted to collect information on Bali bulls carcass traits estimation as one of theselection criteria using ultrasound. Ultrasonic estimation of carcass traits such as M. longissimusthoracis area (MLTA, Subcutaneous Fat Thickness (SFT, Inter Muscular Fat Thickness (IMFT, RibThickness (RT and Beef Marbling Score (BMS were obtained from 92 head of bulls at Barru districtand 74 head of bulls at Bone district, South Sulawesi, Indonesia. The carcass traits estimation werescanned between the 6th - 7th ribs using ultrasound. The ultrasound is made of Fujihira Super-Eye FHK,Co. Meat. Ltd. with B-Mode and electronic linear probe, which used frequency of 2 MHz. The carcasstraits estimation photos were printed by video-copy machine (Aloka Co. Ltd., SSZ-300S. The dataobtained were analyzed using basic statistic and was discussed descriptively. The averages of all carcasstraits estimation of the Bali bull at Bone district at 12, 18 and 24 months of ages were higher than thoseat Barru district. The MLTA estimation of Bali bulls at Bone and Barru districts were 18.0 cm2, 24.3cm2, 23.8 cm2 Vs 16.6 cm2, 18.5 cm2, 23.3 cm2, respectively; the BMS estimated were 0.14, 0.24 and0.20 Vs 0.00, 0.15 and 0.17, respectively; the SFT estimation were 0.26 mm, 0.33 mm, 0.34 mm Vs0.28 mm, 0.26 mm, 0.34 mm, respectively; the IMFT estimation were 1.13 mm, 1.24 mm, 1.31 mm Vs0.97 mm, 1.06 mm, 1.14 mm, respectively; the RT estimation were 2.04 mm, 2.52 mm, 2.72 mm Vs1.19 mm, 2.12 mm, 2.30 mm, respectively. The growth of MLTA, SFT, IMFT, RT and BMS of thebulls of Bali cattle at the 12, 18 and 24 months of age were not reaching the optimally performances,yet. Therefore the selection process of the bulls of Bali cattle to be candidate of sire based on theestimation of carcass traits should be done after since 4 years of age.

  13. THE PERMEABILITY OF THE SCLERAL TISSUE FOR ULTRAVIOLET A IN THE EXPERIMENT

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2017-01-01

    Full Text Available Purpose: to evaluate the permeability of the scleral tissue for ultraviolet A (UVA.Materials and Methods. The study was conducted on 15 cadaver porcine eyes. Rectangular scleral flap 12*15 mm was cut out from each eyeball. The thickness of the sample was measured with a digital caliper. The outer surface of the scleral flap was irradiated with ultraviolet A. A sensor of the UV-radiometer was placed under the sample. It measured the UVA irradiance passing through the sclera. The absorption coefficient of ultraviolet A by the sclera was calculated from the formula derived from the Bouguer-Lambert Beer law: , where  E0 — the absorption coefficient, mm-1;  — irradiance of the transmitted light, mW/cm2; I0 — irradiance of the received light, mW/cm2; — thickness of the sclera, mm.Results. The absorption coefficient of ultraviolet A by the sclera was 4,91±0,43 mm-1. According literature the threshold damaging radiation for retina is 7.7 J/cm2. Substituting these values in the converted formula of the Bouguer-Lambert-Beer law, we can derive an equation for calculating the threshold UVA irradiation dose of the sclera: , where 0 — the threshold UVA irradiation dose of the sclera, J/cm2;  — the base of the natural logarithm; — thickness of the sclera, mm.Conclusion. The absorption coefficient of ultraviolet A by the cadaver porcine sclera is 4,91±0,43 mm-1. The derived formula of the threshold UVA irradiation dose of the sclera calculating allows to avoid the threatening for the retina procedure parameters in the performance of the scleral crosslinking with riboflavin/UVA.

  14. A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes.

    Science.gov (United States)

    Xu, Bin; Ye, Min-Ling; Yu, Yu-Xiang; Zhang, Wei-De

    2010-07-26

    In this report, a highly sensitive amperometric sensor based on MnO(2)-modified vertically aligned multiwalled carbon nanotubes (MnO(2)/VACNTs) for determination of hydrogen peroxide (H(2)O(2)) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO(2)/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H(2)O(2) at the MnO(2)/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO(2)/VACNTs nanocomposite electrode exhibits a linear dependence (R=0.998) on the concentration of H(2)O(2) from 1.2 x 10(-6)M to 1.8 x 10(-3)M, a high sensitivity of 1.08 x 10(6) microA M(-1) cm(-2) and a detection limit of 8.0 x 10(-7) M (signal/noise=3). Meanwhile, the MnO(2)/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO(2)/VACNTs nanocomposite electrode was applied for the determination of trace of H(2)O(2) in milk with high accuracy, demonstrating its potential for practical application. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Amperometric, screen-printed, glucose biosensor for analysis of human plasma samples using a biocomposite water-based carbon ink incorporating glucose oxidase.

    Science.gov (United States)

    Crouch, Eric; Cowell, David C; Hoskins, Stephen; Pittson, Robin W; Hart, John P

    2005-12-01

    This paper describes the optimisation of a screen-printing water-based carbon ink containing cobalt phthalocyanine (CoPC) and glucose oxidase (GOD) for the fabrication of a glucose biosensor. To optimise the performance of the biosensor, the loadings of the electrocatalyst (CoPC) and enzyme (GOD) were varied. It was found that the maximum linear range was achieved with a CoPC loading of 20% (m/m, relative to the mass of carbon) and a GOD loading of 628 U per gram of carbon. In our studies we chose to employ chronoamperometry, as this technique is commonly used for commercial devices. The optimum operating applied potential was found to be +0.5 V, following an incubation period of 60 s. The optimum supporting electrolyte was found to be 0.05 M phosphate buffer at pH 8.0, which resulted in a linear range of 0.2-5 mM, the former represents the detection limit. The sensitivity was 1.12 microA mM(-1). The effect of temperature was also investigated, and it was found that 40 degrees C gave optimal performance. The resulting amperometric biosensors were evaluated by measuring the glucose concentrations for 10 different human plasma samples containing endogenous glucose and also added glucose. The same samples were analysed by a standard spectrophotometric method, and the results obtained by the two different methods were compared. A good correlation coefficient (R(2) = 0.95) and slope (0.98) were calculated from the experimental data, indicating that the new devices hold promise for biomedical studies.

  16. The Monte Carlo evaluation of noise and resolution properties of granular phosphor screens

    International Nuclear Information System (INIS)

    Liaparinos, P F; Kandarakis, I S

    2009-01-01

    The imaging performance of phosphor screens, used as x-ray detectors in diagnostic medical imaging systems, is affected by their both noise and resolution properties. Amplification and blurring processes are due to a sequence of conversion stages within the screen which contribute to fluctuations in the number and spatial distribution of the optical quanta recorded by the optical detector (e.g. film, television camera, CCD, etc). The purpose of this paper is to investigate the stochastic noise arising from granularity as well as the variation of spatial resolution of granular fluorescent screens in terms of the detector's structure. Using a custom-validated Monte Carlo model, the parameters of interest were evaluated for the widely used Gd 2 O 2 S:Tb phosphor material. We have studied the variations of (i) the modulation transfer function, (ii) the Swank factor and (iii) the zero-frequency detective quantum efficiency (DQE), under several conditions employed in conventional and digital mammography and radiology. Several evaluations are provided for the imaging metrics as a function of the x-ray energy (18 keV, 49 keV and 51 keV), phosphor coating weight (20 mg cm -2 , 34 mg cm -2 and 60 mg cm -2 ), grain size (from 4 μm up to 13 μm) and packing density (from 50% up to 85%). It was found that screens of high packing density can combine high zero-frequency DQE with improved resolution properties. For a digital mammographic imaging system (34 mg cm -2 , 18 keV), a packing density of 85% can improve the spatial resolution of the screen by 1.6 cycles mm -1 in comparison to that of 50% packing density. Similarly, for radiographic cases (60 mg cm -2 , 49 keV), the spatial resolution can be improved by 1.7 cycles mm -1 . The aforementioned findings provide the resolution benefits of using high packing density screens.

  17. Highly Efficient Laser Scribed Graphene Electrodes for On-Chip Electrochemical Sensing Applications

    KAUST Repository

    Nayak, Pranati

    2016-08-11

    This study reports the fabrication of flexible electrochemical sensors using a direct-write laser scribing process that transforms commercial polyimide sheet into graphitic carbon with self-standing porous 3D morphology, and abundant edge planes. The heterogeneous electron transfer rate (k0) of the laser scribed graphene (LSG) electrodes for both inner-sphere and outer-sphere redox mediators, ferrocyanide ([Fe(CN)6]4-) and hexaammineruthenium ([Ru(NH3)6]3+) are estimated to be 0.1150 and 0.0868 cm s-1, respectively. These values are significantly higher than those for similar carbon based materials, which this study ascribes to the binder free 3D porous network of LSG with enriched edge plane sites. Further, k0 is enhanced up to 0.2823 and 0.2312 cm s-1 for inner and outer-sphere redox mediators by selective anchoring of Pt nanoparticles over LSG. The LSG electrodes exhibit significantly improved electrocatalytic activity toward oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Consequently, the detection of these biomarkers is achieved with high sensitivity of 237.76 and 250.69 μA mm-1 cm-2 (AA), 2259.9 and 6995.6 μA mm-1 cm-2 (DA) and 5405 and 8289 μA mm-1 cm-2 (UA) for LSG and Pt/LSG electrodes, respectively, in a wide concentration range. These results outperform previously reported 2D/3D graphene based electrodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Amide group anchored glucose oxidase based anodic catalysts for high performance enzymatic biofuel cell

    Science.gov (United States)

    Chung, Yongjin; Ahn, Yeonjoo; Kim, Do-Heyoung; Kwon, Yongchai

    2017-01-01

    A new enzyme catalyst is formed by fabricating gold nano particle (GNP)-glucose oxidase (GOx) clusters that are then attached to polyethyleneimine (PEI) and carbon nanotube (CNT) with cross-linkable terephthalaldehyde (TPA) (TPA/[CNT/PEI/GOx-GNP]). Especially, amide bonds belonging to TPA play an anchor role for incorporating rigid bonding among GNP, GOx and CNT/PEI, while middle size GNP is well bonded with thiol group of GOx to form strong GNP-GOx cluster. Those bonds are identified by chemical and electrochemical characterizations like XPS and cyclic voltammogram. The anchording effect of amide bonds induces fast electron transfer and strong chemical bonding, resulting in enhancements in (i) catalytic activity, (ii) amount of immobilized GOx and (ii) performance of enzymatic biofuel cell (EBC) including the catalyst. Regarding the catalytic activity, the TPA/[CNT/PEI/GOx-GNP] produces high electron transfer rate constant (6 s-1), high glucose sensitivity (68 μA mM-1 cm-2), high maximum current density (113 μA cm-2), low charge transfer resistance (17.0 Ω cm2) and long-lasting durability while its chemical structure is characterized by XPS confirming large portion of amide bond. In EBC measurement, it has high maximum power density (0.94 mW cm-2) compatible with catalytic acitivity measurements.

  19. Molecular Catalysis at Polarized Interfaces Created by Ferroelectric BaTiO3 (Postprint)

    Science.gov (United States)

    2017-02-06

    densities of 20–120 mC cm2 are considerably larger than what is accessible in the parallel plate cell at voltages below the dielectric breakdown limit (at...attachment. The results of reactions performed with 4b are summarized in Fig. 5. When used as a homogeneous catalyst , 2 mM 4b reacted with 2mM 1 in CH2Cl2 to...exploited to control the selectivity of non-faradaic reactions. Polarized interfaces are commonly prepared by applying a voltage to an electrode in

  20. A Highly Sensitive Nonenzymatic Glucose Biosensor Based on the Regulatory Effect of Glucose on Electrochemical Behaviors of Colloidal Silver Nanoparticles on MoS₂†.

    Science.gov (United States)

    Anderson, Kash; Poulter, Benjamin; Dudgeon, John; Li, Shu-En; Ma, Xiang

    2017-08-05

    A novel and highly sensitive nonenzymatic glucose biosensor was developed by nucleating colloidal silver nanoparticles (AgNPs) on MoS₂. The facile fabrication method, high reproducibility (97.5%) and stability indicates a promising capability for large-scale manufacturing. Additionally, the excellent sensitivity (9044.6 μA mM -1 cm -2 ), low detection limit (0.03 μM), appropriate linear range of 0.1-1000 μM, and high selectivity suggests that this biosensor has a great potential to be applied for noninvasive glucose detection in human body fluids, such as sweat and saliva.

  1. Operation of CEBAF with heavy beamloading

    International Nuclear Information System (INIS)

    Hutton, A.

    1997-01-01

    CEBAF is a 4 GeV, 200 microA five-pass recirculating superconducting electron accelerator that has been operating for nuclear physics research at full energy since November 95. The beam current has been increased to over 180 microA at 4 GeV with the maximum current in the linac over 900 microA. The superconducting cavities operate in a regime where the beam-induced voltage is comparable to the accelerating gradient. The operational limits and the issues required to maintain stable operation of the 1,497 MHz superconducting cavities will be discussed, together with the implications for the other accelerator systems. There are three experimental Halls which can run simultaneously with three interleaved 499 MHz bunch trains and RF separators. Operation with simultaneous beams to two Halls is now routine, and simultaneous three beam operation has been demonstrated. The maximum design current per bunch train (120 microA) has been achieved. Hall B eventually requires beam currents as low as 1 nA (200 pA has been delivered) simultaneous with delivery of up to 200 microA to the other Halls. The required beam current ratio of 10,000 has been achieved; development of 1 nA beam position monitors continues

  2. The short-circuit current of the ileum, but not the colon, is altered in the streptozotocin diabetic rat.

    Science.gov (United States)

    Forrest, Abigail; Makwana, Rajesh; Parsons, Mike

    2006-02-01

    Ion transport in control and streptozotocin-diabetic rat colon and ileum was studied using the Ussing chamber technique. No differences were observed between control and diabetic colonic mucosal short-circuit current under either basal or carbachol (100 nmol/L-1 micromol/L)-stimulated or prostaglandin E2 (100 nmol/L-1 micromol/L)-stimulated conditions. Similarly to colonic tissues, no differences in the short circuit current in either carbachol-stimulated or prostaglandin E2-stimulated tissues were observed between control and diabetic ileal mucosa. The basal diabetic ileal short circuit current (99.58 +/- 22.67 microA) was significantly greater than that of control ileal tissues (29.67 +/- 4.45 microA). This difference was abolished by the sodium-glucose-cotransporter inhibitor, phloridzin (50 micromol/L) (118.00 +/- 28.09 microA vs. 25.60 +/- 4.59 microA) and was also prevented by the replacement of glucose with mannitol in the buffer bathing the apical side of the tissue (control: 17.05 +/- 5.85 microA vs. 17.90 +/- 3.10 microA). Acetazolamide (450 micromol/L; a carbonic anhydrase inhibitor), amiloride, and bumetanide (100 micromol/L each; Na+-channel blockers), piroxicam (50 micromol/L; a COX1 cyclooxygenase inhibitor), and ouabain (1 mmol/L; a K+ transport inhibitor) had no effect on the basal short circuit current of either control or diabetic ileal tissues. This indicated that the alteration in the basal short circuit current of diabetic ileal tissues was due to a change in cellular glucose transport, whereas the evoked changes in short circuit current were unaffected by the diabetic state.

  3. Enzymatic and non-enzymatic electrochemical glucose sensor based on carbon nano-onions

    Science.gov (United States)

    Mohapatra, Jeotikanta; Ananthoju, Balakrishna; Nair, Vishnu; Mitra, Arijit; Bahadur, D.; Medhekar, N. V.; Aslam, M.

    2018-06-01

    A high sensitive glucose sensing characteristic has been realized in carbon nano-onions (CNOs). The CNOs of mean size 30 nm were synthesized by an energy-efficient, simple and inexpensive combustion technique. These as-synthesized CNOs could be employed as an electrochemical sensor by covalently immobilizing the glucose oxidase enzyme on them via carbodiimide chemistry. The sensitivity achieved by such a sensor is 26.5 μA mM-1 cm-2 with a linear response in the range of 1-10 mM glucose. Further to improve the catalytic activity of the CNOs and also to make them enzyme free, platinum nanoparticles of average size 2.5 nm are decorated on CNOs. This sensor fabricated using Pt-decorated CNOs (Pt@CNOs) nanostructure has shown an enhanced sensitivity of 21.6 μA mM-1 cm-2 with an extended linear response in the range of 2-28 mM glucose. Through these attempts we demonstrate CNOs as a versatile biosensing platform.

  4. Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

    Science.gov (United States)

    Xia, Lei; Song, Jian; Xu, Ru; Liu, Dali; Dong, Biao; Xu, Lin; Song, Hongwei

    2014-09-15

    The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs. Moreover, photoelectrochemical detection for glucose using the electrode was realized and the sensitivity approached to 52.4 µA mM(-1) cm(-2), which was about four times to electrochemical detection (14.1 µA mM(-1) cm(-2)). It indicated that photoelectrochemical detection can highly improve the sensor performance than conventional electrochemical method. It also exhibited an excellent anti-interference property and a good stability at the same time. This work provides a promising approach for realizing excellent photoelectrochemical biosensor of similar semiconductor photoelectric material. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. A highly sensitive NADH sensor based on a mycelium-like nanocomposite using graphene oxide and multi-walled carbon nanotubes to co-immobilize poly(luminol) and poly(neutral red) hybrid films.

    Science.gov (United States)

    Chiang Lin, Kuo; Yu Lai, Szu; Ming Chen, Shen

    2014-08-21

    Hybridization of poly(luminol) (PLM) and poly(neutral red) (PNR) has been successfully performed and further enhanced by a conductive and steric hybrid nanotemplate using graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs). The morphology of the PLM-PNR-MWCNT-GO mycelium-like nanocomposite is studied by SEM and AFM and it is found to be electroactive, pH-dependent, and stable in the electrochemical system. It shows electrocatalytic activity towards NADH with a high current response and low overpotential. Using amperometry, it has been shown to have a high sensitivity of 288.9 μA mM(-1) cm(-2) to NADH (Eapp. = +0.1 V). Linearity is estimated in a concentration range of 1.33 × 10(-8) to 1.95 × 10(-4) M with a detection limit of 1.33 × 10(-8) M (S/N = 3). Particularly, it also shows another linear range of 2.08 × 10(-4) to 5.81 × 10(-4) M with a sensitivity of 151.3 μA mM(-1) cm(-2). The hybridization and activity of PLM and PNR can be effectively enhanced by MWCNTs and GO, resulting in an active hybrid nanocomposite for determination of NADH.

  6. Phase dependency of electrotonic spread of hyperpolarizing current pulses in the rabbit sinoatrial node

    NARCIS (Netherlands)

    Duivenvoorden, J. J.; Bouman, L. N.; Bukauskas, F. F.; Opthof, T.; Jongsma, H. J.

    1990-01-01

    Electrotonic current spread in the SA node of the rabbit was measured by means of hyperpolarizing current pulses (1 to 10 microA, 60 ms), which were injected intracellularly through a K(+)-perfused suction electrode. The pulses were applied at the beginning, middle or end of the diastolic

  7. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres

    Science.gov (United States)

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-03-01

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a sensitivity of 0.56 mA mM-1 cm-2, a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM-1 cm-2 and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a

  8. Amperometric biosensor based on carbon nanotubes coated with polyaniline/dendrimer-encapsulated Pt nanoparticles for glucose detection

    International Nuclear Information System (INIS)

    Xu Lihuan; Zhu Yihua; Yang Xiaoling; Li Chunzhong

    2009-01-01

    A novel amperometric glucose biosensor based on the nanocomposites of multi-wall carbon nanotubes (CNT) coated with polyaniline (PANI) and dendrimer-encapsulated Pt nanoparticles (Pt-DENs) is prepared. CNT coated with protonated PANI is in situ synthesized and Pt-DENs is absorbed on PANI/CNT composite surface by self-assembly method. Then Glucose oxidase (GOx) is crosslink-immobilizated onto Pt-DENs/PANI/CNT composite film. The results show that the fabricated GOx/Pt-DENs/PANI/CNT electrode exhibits excellent response performance to glucose, such as low detection limit (0.5 μM), wide linear range (1 μM-12 mM), short response time (about 5 s), high sensitivity (42.0 μA mM -1 cm -2 ) and stability (83% remains after 3 weeks).

  9. Development of an enzyme free glucose sensor based on copper oxide-graphene composite by using green reducing agent ascorbic acid

    Science.gov (United States)

    Palve, Yogesh Pandit; Jha, Neetu

    2018-05-01

    In this research work we have developed high sensitive and selective glucose sensor based on copper oxide-graphene composite which is prepared by green synthesis method and used for nonenzymatic glucose sensor. In present paper we report that present method highly selective, simple, efficient, accurate, ecofriendly, less toxic. The prepared composite were characterized by material characterization like SEM, XRD and also by electrochemical characterization like CV, chronoamperometry represents that copper oxide-graphene shows excellent electrocatalytic activity towards glucose, exhibiting a good sensitivity of 103.84 µA mM-1 cm-2, a fast response time 2s, a low detection limit 0.00033µM and linear range from 10 µM-3000 µM. The present sensor can successfully apply for determination of glucose concentration in human blood sample.

  10. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    International Nuclear Information System (INIS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-01-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM -1 cm -2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  11. Whole systems thinking for sustainable water treatment design

    Science.gov (United States)

    Huggins, Mitchell Tyler

    satisfactory power density of 532 +/- 18 mW/m-2 and 457 +/- 20 mW/m-2 respectively, compared to GAC with 674 +/- 10 mW/m-2 and GG with 566 +/- 5 mW/m-2 (normalized to cathode projected surface area), as an anode material in a two-chamber MFC. BCc and BCp had BET-N2 surface area measurements of 429 cm2 g -1 and 470 cm2 g-1 respectively, lower than industrial GAC with 1248 cm2 g-1 but several orders of magnitude higher that GG with 0.44 cm2 g-1 . BCc and BCp had a lower surface resistance of 3+/-1Ω mm -1 and 6+/-1 Ω mm-1 than 8+/-2Ω mm -1 for GAC, but higher that GG with 0.4+/-0.5 Ω mm -1. We also investigated the life-cycle impact and estimated cost of biochar as an electrode material. Although there is no well-established market price for biochar, conservative estimates place the costs around 51-356 US/tonne, up to ten times cheaper that GAC (500-2500 US/tonne) and GGs (500-800 US$/tonne) with significantly greater life-cycle advantages.

  12. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    Science.gov (United States)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  13. Holographic investigation of silver electromigration in nano-sized As2S3 films

    Science.gov (United States)

    Sainov, S.; Todorov, R.; Bodurov, I.; Yovcheva, Temenuzhka

    2013-10-01

    Holographic gratings with a diffraction efficiency (DE) greater than 8% and a spatial resolution of 2237 mm-1 are recorded in very thin As2S3 films with a thickness of 100 nm. Silver photo-diffusion is observed during the holographic recording process while applying a corona discharge. We use the method of holographic grating relaxation spectroscopy (forced Rayleigh scattering) based on the evanescent waves to determine that the silver diffusion coefficient in the thin As2S3 film is in the range of (0.9-10.3) × 10-13 cm2 s-1 depending on the corona charge polarity. This work is dedicated to the 90th anniversary of the birth of Academician Jordan Malinowski.

  14. Mango core inner shell membrane template-directed synthesis of porous ZnO films and their application for enzymatic glucose biosensor

    Science.gov (United States)

    Zhou, Yu; Wang, Lei; Ye, Zhizhen; Zhao, Minggang; Cai, Hui; Huang, Jingyun

    2013-11-01

    Micro/nano-porous ZnO films were synthesized through a simple biotemplate-directed method using mango core inner shell membranes as templates. The achieved ZnO films with wrinkles on the surface are combined of large holes and small pores in the bulk. High specific surface area, numerous microspaces, and small channels for fluid circulation provided by this unique structure along with the good biocompatibility and electron communication features of ZnO material make the product an ideal platform for the immobilization of enzymes The fabricated glucose biosensor based on the porous ZnO films exhibits good selective detection ability of analyte with good stability, high sensitivity of 50.58 μA cm-2 mM-1 and a wide linear range of 0.2-5.6 mM along with a low detection limit of 10 μM.

  15. Chitosan coated on the layers' glucose oxidase immobilized on cysteamine/Au electrode for use as glucose biosensor.

    Science.gov (United States)

    Zhang, Yawen; Li, Yunqiu; Wu, Wenjian; Jiang, Yuren; Hu, Biru

    2014-10-15

    A glucose biosensor was developed via direct immobilization of glucose oxidase (GOD) by self-assembled cysteamine monolayer on Au electrode surface followed by coating chitosan on the surface of electrode. In this work, chitosan film was coated on the surface of GOD as a protection film to ensure the stability and biocompatibility of the constructed glucose biosensor. The different application ranges of sensors were fabricated by immobilizing varied layers of GOD. The modified surface film was characterized by a scanning electron microscope (SEM) and the fabrication process of the biosensor was confirmed through electrochemical impedance spectroscopy (EIS) of ferrocyanide. The performance of cyclic voltammetry (CV) in the absence and presence of 25 mM glucose and ferrocenemethanol showed a diffusion-controlled electrode process and reflected the different maximum currents between the different GOD layers. With the developed glucose biosensor, the detection limits of the two linear responses are 49.96 μM and 316.8 μM with the sensitivities of 8.91 μA mM(-1)cm(-2) and 2.93 μA mM(-1)cm(-2), respectively. In addition, good stability (up to 30 days) of the developed biosensor was observed. The advantages of this new method for sensors construction was convenient and different width ranges of detection can be obtained by modified varied layers of GOD. The sensor with two layers of enzyme displayed two current linear responses of glucose. The present work provided a simplicity and novelty method for producing biosensors, which may help design enzyme reactors and biosensors in the future. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Microwave-assisted synthesis of graphene modified CuO nanoparticles for voltammetric enzyme-free sensing of glucose at biological pH values.

    Science.gov (United States)

    Foroughi, Faranak; Rahsepar, Mansour; Hadianfard, Mohammad Jafar; Kim, Hasuck

    2017-12-18

    The effect of graphene nanosheets on the glucose sensing performance of CuO powders was investigated. CuO and graphene-modified CuO nanoparticles (NPs) were fabricated by microwave-assisted synthesis and characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The material was placed on a glassy carbon electrode (GCE) which then was characterized by cyclic voltammetry and chronoamperometry with respect to the capability of sensing glucose both at pH 13 and pH 7.4. The results revealed that the modified GCE has a fast and selective linear response to glucose at pH 13 that covers the 0.21 μM to 12 mM concentration range, with a 0.21 μM low detection limit. The presence of graphene nanosheets results in an improved sensitivity which is to 700 μA mM -1  cm -2 . In solution of pH 7.4, the respective data are a linear analytical range from 5 to 14 mM; a 5 μM LOD and a sensitivity of 37.63 μA mM -1  cm -2 at working potential of -0.05 V (vs. Ag/AgCl) and scan rate of 50 mV s -1 . Ascorbic acid, dopamine, uric acid, sucrose, maltose and fructose do not interfere. Graphical abstract ᅟ.

  17. Direct electron transfer of glucose oxidase and dual hydrogen peroxide and glucose detection based on water-dispersible carbon nanotubes derivative.

    Science.gov (United States)

    Chen, Hsiao-Chien; Tu, Yi-Ming; Hou, Chung-Che; Lin, Yu-Chen; Chen, Ching-Hsiang; Yang, Kuang-Hsuan

    2015-03-31

    A water-dispersible multi-walled carbon nanotubes (MWCNTs) derivative, MWCNTs-1-one-dihydroxypyridine (MWCNTs-Py) was synthesis via Friedel-Crafts chemical acylation. Raman spectra demonstrated the conjugated level of MWCNTs-Py was retained after this chemical modification. MWCNTs-Py showed dual hydrogen peroxide (H2O2) and glucose detections without mutual interference by adjusting pH value. It was sensitive to H2O2 in acidic solution and displayed the high performances of sensitivity, linear range, response time and stability; meanwhile it did not respond to H2O2 in neutral solution. In addition, this positively charged MWCNTs-Py could adsorb glucose oxidase (GOD) by electrostatic attraction. MWCNTs-Py-GOD/GC electrode showed the direct electron transfer (DET) of GOD with a pair of well-defined redox peaks, attesting the bioactivity of GOD was retained due to the non-destroyed immobilization. The high surface coverage of active GOD (3.5×10(-9) mol cm(-2)) resulted in exhibiting a good electrocatalytic activity toward glucose. This glucose sensor showed high sensitivity (68.1 μA mM(-1) cm(-2)) in a linear range from 3 μM to 7 mM in neutral buffer solution. The proposed sensor could distinguish H2O2 and glucose, thus owning high selectivity and reliability. Copyright © 2015. Published by Elsevier B.V.

  18. Fabrication of a methanol chemical sensor based on hydrothermally prepared α-Fe₂O₃ codoped SnO₂ nanocubes.

    Science.gov (United States)

    Rahman, Mohammed M; Khan, Sher Bahadar; Jamal, A; Faisal, M; Asiri, Abdullah M

    2012-06-15

    We have prepared calcined α-Fe(2)O(3) codoped SnO(2) nanocubes (NCs) by a hydrothermal method using reducing agents in alkaline medium. The codoped NCs were characterized by UV/vis, FT-IR, and Raman spectroscopy, powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). They were deposited on a silver electrode (AgE, surface area, 0.0216 cm(2)) to give a sensor with a fast response towards methanol in liquid phase. The sensor also exhibits good sensitivity and long-term stability, and enhanced electrochemical response. The calibration plot is linear (r(2)=0.9809) over the 0.25 mmol L(-1) to 0.25 mol L(-1) methanol concentration range. The sensitivity is ∼5.79 μA cm(-2)mM(-1), and the detection limit is 0.16 ± 0.02 mmol L(-1) (signal-to-noise ratio, at a SNR of 3). We also discuss possible future prospective uses of this codoped semiconductor nanomaterial in terms of chemical sensing. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. High Discharge Energy Density at Low Electric Field Using an Aligned Titanium Dioxide/Lead Zirconate Titanate Nanowire Array.

    Science.gov (United States)

    Zhang, Dou; Liu, Weiwei; Guo, Ru; Zhou, Kechao; Luo, Hang

    2018-02-01

    Polymer-based capacitors with high energy density have attracted significant attention in recent years due to their wide range of potential applications in electronic devices. However, the obtained high energy density is predominantly dependent on high applied electric field, e.g., 400-600 kV mm -1 , which may bring more challenges relating to the failure probability. Here, a simple two-step method for synthesizing titanium dioxide/lead zirconate titanate nanowire arrays is exploited and a demonstration of their ability to achieve high discharge energy density capacitors for low operating voltage applications is provided. A high discharge energy density of 6.9 J cm -3 is achieved at low electric fields, i.e., 143 kV mm -1 , which is attributed to the high relative permittivity of 218.9 at 1 kHz and high polarization of 23.35 µC cm -2 at this electric field. The discharge energy density obtained in this work is the highest known for a ceramic/polymer nanocomposite at such a low electric field. The novel nanowire arrays used in this work are applicable to a wide range of fields, such as energy harvesting, energy storage, and photocatalysis.

  20. Electric field stimulation through a substrate influences Schwann cell and extracellular matrix structure

    Science.gov (United States)

    Nguyen, Hieu T.; Wei, Claudia; Chow, Jacqueline K.; Nguy, Lindsey; Nguyen, Hieu K.; Schmidt, Christine E.

    2013-08-01

    Objective. Electric field (EF) stimulation has been used to cue cell growth for tissue engineering applications. In this study, we explore the electrical parameters and extracellular mechanisms that elicit changes in cell behavior when stimulated through the substrate. Approach. Rat Schwann cell morphology was compared when exposed to EF through the media or a conductive indium tin oxide substrate. Ionic and structural effects were then analyzed on Matrigel and collagen I, respectively. Main results. When stimulating through media, cells had greater alignment perpendicular to the EF with higher current densities (106 mA cm-2 at 245 mV mm-1), and reached maximum alignment within 8 h. Stimulation through the substrate with EF (up to 110 mV mm-1) did not affect Schwann cell orientation, however the EF caused extracellular matrix (ECM) coatings on substrates to peel away, suggesting EF can physically change the ECM. Applying alternating current (ac) 2-1000 Hz signals through the media or substrate both caused cells to flatten and protrude many processes, without preferential alignment. Matrigel exposed to a substrate EF of 10 mV mm-1 for 2 h had a greater calcium concentration near the cathode, but quickly dissipated when the EF was removed. Schwann cells seeded 7 d after gels were exposed to substrate EF still aligned perpendicular to the EF direction. Microscopy of collagen I exposed to substrate EF shows alignment and bundling of fibrils. Significance. These findings demonstrate EF exposure can control Schwann cell alignment and morphology, change ECM bulk/surface architecture, and align ECM structures.

  1. A low-power wide range transimpedance amplifier for biochemical sensing.

    Science.gov (United States)

    Rodriguez-Villegas, Esther

    2007-01-01

    This paper presents a novel low voltage and low power transimpedance amplifier for amperometric potentiostats. The power is optimized by having three different gain settings for different current ranges, which can be programmed with a biasing current. The voltage ranges have been optimized by using FGMOS transistors in a second voltage amplification stage that simultaneously allow for offset calibration as well as independent biasing of the gates. The circuit operates with input currents from 1 pA to 1 microA, with a maximum power supply voltage of 1.5 V and consumes 82.5 nW, 9.825 microW, 47.325 microW for currents varying from (1 pA, 0.25 nA), (0.25 nA, 62.5 nA) and (62.5 nA, 1 microA) respectively.

  2. Methods for interpreting lists of affected genes obtained in a DNA microarray experiment

    DEFF Research Database (Denmark)

    Hedegaard, Jakob; Arce, Christina; Bicciato, Silvio

    2009-01-01

    The aim of this paper was to describe and compare the methods used and the results obtained by the participants in a joint EADGENE (European Animal Disease Genomic Network of Excellence) and SABRE (Cutting Edge Genomics for Sustainable Animal Breeding) workshop focusing on post analysis of microa...... a microarray experiment conducted to study the host reactions in broilers occurring shortly after a secondary challenge with either a homologous or heterologous species of Eimeria...

  3. Saturation of subjective reward magnitude as a function of current and pulse frequency.

    Science.gov (United States)

    Simmons, J M; Gallistel, C R

    1994-02-01

    In rats with electrodes in the medial forebrain bundle, the upper portion of the function relating the experienced magnitude of the reward to pulse frequency was determined at currents ranging from 100 to 1,000 microA. The pulse frequency required to produce an asymptotic level of reward was inversely proportional to current except at the lowest currents and highest pulse frequencies. At a given current, the subjective reward magnitude functions decelerated to an asymptote over an interval in which the pulse frequency doubled or tripled. The asymptotic level of reward was approximately constant for currents between 200 and 1,000 microA but declined substantially at currents at or below 100 microA and pulse frequencies at or above 250 to 400 pulses per second. The results are consistent with the hypothesis that the magnitude of the experienced reward depends only on the number of action potentials generated by the train of pulses in the bundle of reward-relevant axons.

  4. Synthesis and Characterization of Network Single Ion Conductors(NSIC) Based On Comb-Branched Polyepoxide Ethers and Lithium Bis(allylmalonato)borate

    International Nuclear Information System (INIS)

    Sun, Xiao-Guang; Kerr, John B.

    2004-01-01

    wt) was cycled at 25 C at a current density of 25 (micro)A cm -2 and showed an initial capacity of 268 mAh g -1 of V 6 O 13 , which stabilized at around 200 mAh g -1 after the first 20 cycles. In the course of DMA measurements on the network single ion conductors it was found that besides the main glass transition (α transition) there was a distinct secondary glass transition (β transition ) for network single ion conductors having five EO units in the side chains while this (the secondary transition) was not clearly visible in the network single ion conductors with shorter side chains (two, three and four EO units). The main glass transition (α transition) was attributed to the backbone network structure of the single ion conductors and secondary glass transition (β transition) appeared to be due to the complexation of lithium by the side-chain chains. Both the main glass transition and the secondary transition were found to shift to higher temperature with increasing salt concentration

  5. Monte Carlo simulation of beam characteristics from small fields based on TrueBeam flattening-filter-free mode

    International Nuclear Information System (INIS)

    Feng, Zhongsu; Yue, Haizhen; Zhang, Yibao; Wu, Hao; Cheng, Jinsheng; Su, Xu

    2016-01-01

    Through the Monte Carlo (MC) simulation of 6 and 10 MV flattening-filter-free (FFF) beams from Varian TrueBeam accelerator, this study aims to find the best incident electron distribution for further studying the small field characteristics of these beams. By incorporating the training materials of Varian on the geometry and material parameters of TrueBeam Linac head, the 6 and 10 MV FFF beams were modelled using the BEAMnrc and DOSXYZnrc codes, where the percentage depth doses (PDDs) and the off-axis ratios (OARs) curves of fields ranging from 4 × 4 to 40 × 40 cm 2 were simulated for both energies by adjusting the incident beam energy, radial intensity distribution and angular spread, respectively. The beam quality and relative output factor (ROF) were calculated. The simulations and measurements were compared using Gamma analysis method provided by Verisoft program (PTW, Freiburg, Germany), based on which the optimal MC model input parameters were selected and were further used to investigate the beam characteristics of small fields. The Full Width Half Maximum (FWHM), mono-energetic energy and angular spread of the resultant incident Gaussian radial intensity electron distribution were 0.75 mm, 6.1 MeV and 0.9° for the nominal 6 MV FFF beam, and 0.7 mm, 10.8 MeV and 0.3° for the nominal 10 MV FFF beam respectively. The simulation was mostly comparable to the measurement. Gamma criteria of 1 mm/1 % (local dose) can be met by all PDDs of fields larger than 1 × 1 cm 2 , and by all OARs of no larger than 20 × 20 cm 2 , otherwise criteria of 1 mm/2 % can be fulfilled. Our MC simulated ROFs agreed well with the measured ROFs of various field sizes (the discrepancies were less than 1 %), except for the 1 × 1 cm 2 field. The MC simulation agrees well with the measurement and the proposed model parameters can be clinically used for further dosimetric studies of 6 and 10 MV FFF beams

  6. Superficial shell insulation in resting and exercising men in cold water.

    Science.gov (United States)

    Veicsteinas, A; Ferretti, G; Rennie, D W

    1982-06-01

    From measurements of subcutaneous fat temperature (Tsf) at known depths below the surface, skin surface temperature (Tsk), and direct skin heat flux (H), the superficial shell isulation (Iss) of the thigh (fat + skin) was calculated as Iss (degrees C.m2.w-1) = (Tsf - Tsk)/H in nine male subjects immersed head out in a well-stirred water bath. Also, at critical water temperature (CWT = 28-33 degrees C), eight of the subjects rested for 3 h, enabling overall maximal tissue insulation (It,max) to be calculated as It,max (degrees C.m2.W-1) = (Tre - Tw)/(0.92 M +/- delta S), where Tre is rectal temperature, Tw is water temperature, M is metabolic rate, and s is loss or gain of body heat. Five subjects performed up to 2 h of mild leg cycling, preceded and followed by 60 min of rest, and both thigh Iss and overall It were measured during exercise. Iss increased from minimal values in Tw greater than 33 degrees C to maximal values (Iss,max) at CWT or below. Iss,max was linearly related to tissue thickness (d) in millimeters of fat plus skin, Iss,max (degrees C.m2.W-1) = 0.0048d-0.0052; r = 0.95, n = 37, and was not influenced by leg exercise up to a metabolic rate of 150 W.m-2 in CWT despite large increases in Tsf and H and large decreases in overall It. The slope of Iss,max vs. depth, 0.0048 degrees C.m2.W-1.mm-1, is almost identical to thermal resistivity of fat in vitro, suggesting that the superficial shell is unperfused in CWT at rest or during mild exercise. When maximal superficial shell insulation (It,ss,max) for the whole body was calculated with allowance for differing fat thicknesses and surface areas of body regions, it could account for only 10-15% of overall It,max at rest and 35-40% of overall It in mild exercise. We suggest that the poorly perfused muscle shell plays a more important role as a defense against cooling at CWT than does the superficial shell (fat + skin), particularly at rest.

  7. Immobilization of glucose oxidase on graphene and cobalt phthalocyanine composite and its application for the determination of glucose.

    Science.gov (United States)

    Mani, Veerappan; Devasenathipathy, Rajkumar; Chen, Shen-Ming; Huang, Sheng-Tung; Vasantha, V S

    2014-11-01

    We described a simple and facile chemical reduction strategy for the preparation of graphene (GR)-cobalt phthalocyanine (CoPc) composite and explored it for the enzymatic determination of glucose. CoPc is an active mediator and electrocatalysts for the immobilization of GOx and determination of glucose. However, it is not stable on the electrode surface and also suffers from lack of conductivity. Here, we have employed GR as the suitable support to stabilize CoPc through simple chemical reduction method and the resulting composite has been used for the glucose biosensor application. Scanning electron microscopy, X-ray diffraction and Energy-dispersive X-ray spectroscopy studies confirmed the successful formation of composite. Direct electron transfer of glucose oxidase (GOx) was observed with well defined redox peaks at the formal potential of -0.44 V. The amount of electroactive GOx (Г) and electron transfer rate constant (ks) were calculated to be 3.77×10(-10) mol cm(-2) and 3.57 s(-1), respectively. The fabricated amperometric biosensor detects glucose in wide linear concentration range from 10 μM to 14.8 mM with high sensitivity of 5.0 9μA mM(-1) cm(-2). The sensor offered very low detection limit (LOD) of 1.6 μM. In addition, practical feasibility of the sensor has been explored in screen printing carbon electrode with accurate determination of glucose present in human blood serum and urine samples. Furthermore, the sensor exhibited appreciable stability, repeatability and reproducibility results. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Efecto de la presión de compactación en las propiedades termofísicas de polvos de arcilla roja elaboradas por atomización

    Directory of Open Access Journals (Sweden)

    G. Peña- Rodríguez

    2010-07-01

    Full Text Available Thermophysical properties are reported at room temperature in function of the compaction pressure applied to range between 50 and 250 kg/cm2 for samples of red clay powder produced by atomization processes (Spray-Dried. The experimental technique used was linear transient heat flow using the KD2 Pro system. Size distribution was determined by sieving, found that the grain size varies between 75 and 600 µm, where 43.6 % of the sample is in the range between 250 and 425 µm, while 1.8% has a grain size less than 75 micrometers. The percentage of moisture present in the sample during the compaction process was between 6 and 7%. The compaction of the sample was performed using a hydraulic press and a steel cylindrical die with internal diameter of 44.45 mm (1 ¾ “, outer diameter 57.15 mm (2 ¼” and a height of 203.2 mm (8 “. The thermophysical parameters measured experimentally were thermal conductivity (k and thermal diffusivity (α, while the thermal effusivity (ε and the specific heat per unit volume (ρc were calculated using the values of α and k using ρc = kα-1 and ε = kα-1/2 expressions. The behaviour of the thermal properties as a function of the compacting pressure (p was analyzed by fitting to experimental data using the Origin Pro Ver 7.0.software. The analysis of the density as a function of the pressure, reported the apparent pressure po = 153 Kg/cm2= 15 MPa, this pressure to describe the boundary between the plastic and elastic deformation of the particles. The results reported in this paper will be used in the optimization of production processes in the ceramic industries.

  9. Development of NaI(Tl) scintillating films for imaging soft x-rays

    International Nuclear Information System (INIS)

    Shepherd, J.A.

    1993-01-01

    Thin film NaI(Tl) scintillators, of areas of up to 130 cm 2 , have been fabricated and characterized for use on soft x-ray imaging photomultiplier tubes. Relevant parameters of photon-counting imaging detectors are defined and used to predict the performance of several materials, including CsI(Na), CsI(Tl), CaF 2 (Eu), Lu 2 (SiO 4 )O:Ce, and NaI(Tl), as thin film scintillators on fiber optic substrates. Also, x-ray imaging methodologies are compared. The NaI(Tl) films were vapor-deposited onto quartz and fiber optic substrates using a powder flash deposition technique. When compared to single crystal NaI(Tl), the films were found to have equally high light yield but lower energy resolution. Light yield optimization was studied in detail including the effects of substrate temperature, activator concentration in the evaporant, and boat temperature. Spatial resolution as well as parallax errors are discussed and measured for film thicknesses up to 61 μm. A technique is described that can substantially increase the light collection of high index films on fiber optic disks. The light collection was improved by 20% by coating the disk with potassium silicate before the NaI(Tl) deposition. Large area films, up to 130 cm 2 , had a spatial uniformity of response within ±1.5% for count rate and ±3.5% for light yield, and their spatial resolution exceeded 16.6 lp mm -1 when deposited onto fiber optic substrates. The 8-keV x-ray detection efficiency of the microchannel plate imaging photomultiplier tube coupled to a NaI(Tl) film scintillator is predicted to be 88%. Other uses for the films are also described

  10. A CdZnTe slot-scanned detector for digital mammography

    International Nuclear Information System (INIS)

    Mainprize, James G.; Ford, Nancy L.; Yin Shi; Gordon, Eli E.; Hamilton, William J.; Tuemer, Tuemay O.; Yaffe, Martin J.

    2002-01-01

    A new high-resolution detector has been developed for use in a slot-scanned digital mammography system. The detector is a hybrid device that consists of a CCD operating in time-delay integration mode that is bonded to a 150-μm-thick CdZnTe photoconductor array. The CCD was designed with a detector element pitch of 50 μm. Two devices were evaluated with differing crystalline quality. Incomplete charge collection was a source of reduction in DQE. This occurs in both devices due to characteristically low mobility-lifetime products for CdZnTe, with the greatest losses demonstrated by the multicrystalline sample. The mobility-lifetime products for the multicrystalline device were found to be 2.4x10 -4 and 4.0x10 -7 cm 2 /V for electrons and holes, respectively. The device constructed with higher quality single crystal CdZnTe demonstrated mobility-lifetime products of 1.0x10 -4 and 4.4x10 -6 cm 2 /V for electrons and holes. The MTF and DQE for the device were measured at several exposures and results were compared to predictions from a linear systems model of signal and noise propagation. The MTF at a spatial frequency of 10 mm -1 exceeded 0.18 and 0.56 along the scan and slot directions, respectively. Scanning motion and CCD design limited the resolution along the scan direction. For an x-ray beam from a tungsten target tube with 40 μm molybdenum filtration operated at 26 kV, the single crystal device demonstrated a DQE(0) of 0.70±0.02 at 7.1x10 -6 C/kg (27 mR) exposure to the detector, despite its relatively poor charge collection efficiency

  11. Optical, structural, and chemical properties of CR-39 implanted with 5.2 MeV doubly charged carbon ions

    Science.gov (United States)

    Ali, Dilawar; Butt, M. Z.; Ishtiaq, Mohsin; Waqas Khaliq, M.; Bashir, Farooq

    2016-11-01

    Poly-allyl-diglycol-carbonate (CR-39) specimens were irradiated with 5.2 MeV doubly charged carbon ions using Pelletron accelerator. Ion dose was varied from 5 × 1013 to 5 × 1015 ions cm-2. Optical, structural, and chemical properties were investigated by UV-vis spectroscopy, x-ray diffractometer, and FTIR/Raman spectroscopy, respectively. It was found that optical absorption increases with increasing ion dose. Absorption edge shifts from UV region to visible region. The measured opacity values of pristine and ion implanted CR-39 range from 0.0519 to 4.7959 mm-1 following an exponential growth (9141%) with the increase in ion dose. The values of direct and indirect band gap energy decrease exponentially with an increase in ion dose by 59% and 71%, respectively. However, average refractive index in the visible region increases from 1.443 to 2.864 with an increase in ion dose, by 98%. A linear relation between band gap energy and crystallite size was observed. Both the number of carbon atoms in conjugation length and the number of carbon atoms per cluster increase linearly with the increase in ion dose. FTIR spectra showed that on C+2 ions irradiation, the intensity of all bands decreases gradually without appearance of any new band, indicating degradation of polymer after irradiation. Raman spectra revealed that the density of -CH2- group decreases on C+2 ions irradiation. However, the structure of CR-39 is completely destroyed on irradiation with ion dose 1 × 1015 and 5 × 1015 ions cm-2.

  12. LOW-VELOCITY SHOCKS TRACED BY EXTENDED SiO EMISSION ALONG THE W43 RIDGES: WITNESSING THE FORMATION OF YOUNG MASSIVE CLUSTERS

    International Nuclear Information System (INIS)

    Nguyen-Luong, Q.; Martin, P. G.; Motte, F.; Louvet, F.; Hill, T.; Hennemann, M.; Didelon, P.; Carlhoff, P.; Schilke, P.; Lesaffre, P.; Gusdorf, A.; Schneider, N.; Bontemps, S.; Duarte-Cabral, A.; Menten, K. M.; Wyrowski, F.; Bendo, G.; Roussel, H.; Bernard, J.-P.; Bronfman, L.

    2013-01-01

    The formation of high-mass stars is tightly linked to that of their parental clouds. Here, we focus on the high-density parts of W43, a molecular cloud undergoing an efficient event of star formation. Using a column density image derived from Herschel continuum maps, we identify two high-density filamentary clouds, called the W43-MM1 and W43-MM2 ridges. Both have gas masses of 2.1 × 10 4 M ☉ and 3.5 × 10 4 M ☉ above >10 23 cm -2 and within areas of ∼6 and ∼14 pc 2 , respectively. The W43-MM1 and W43-MM2 ridges are structures that are coherent in velocity and gravitationally bound, despite their large velocity dispersion measured by the N 2 H + (1-0) lines of the W43-HERO IRAM large program. Another intriguing result is that these ridges harbor widespread (∼10 pc 2 ) bright SiO (2-1) emission, which we interpret to be the result of low-velocity shocks (≤10 km s –1 ). We measure a significant relationship between the SiO (2-1) luminosity and velocity extent and show that it distinguishes our observations from the high-velocity shocks associated with outflows. We use state-of-the-art shock models to demonstrate that a small percentage (10%) of Si atoms in low-velocity shocks, observed initially in gas phase or in grain mantles, can explain the observed SiO column density in the W43 ridges. The spatial and velocity overlaps between the ridges of high-density gas and the shocked SiO gas suggest that ridges could be forming via colliding flows driven by gravity and accompanied by low-velocity shocks. This mechanism may be the initial conditions for the formation of young massive clusters

  13. Low-velocity Shocks Traced by Extended SiO Emission along the W43 Ridges: Witnessing the Formation of Young Massive Clusters

    Science.gov (United States)

    Nguyen-Lu'o'ng, Q.; Motte, F.; Carlhoff, P.; Louvet, F.; Lesaffre, P.; Schilke, P.; Hill, T.; Hennemann, M.; Gusdorf, A.; Didelon, P.; Schneider, N.; Bontemps, S.; Duarte-Cabral, A.; Menten, K. M.; Martin, P. G.; Wyrowski, F.; Bendo, G.; Roussel, H.; Bernard, J.-P.; Bronfman, L.; Henning, T.; Kramer, C.; Heitsch, F.

    2013-10-01

    The formation of high-mass stars is tightly linked to that of their parental clouds. Here, we focus on the high-density parts of W43, a molecular cloud undergoing an efficient event of star formation. Using a column density image derived from Herschel continuum maps, we identify two high-density filamentary clouds, called the W43-MM1 and W43-MM2 ridges. Both have gas masses of 2.1 × 104 M ⊙ and 3.5 × 104 M ⊙ above >10^{23}\\, {{cm}^{-2}} and within areas of ~6 and ~14 pc2, respectively. The W43-MM1 and W43-MM2 ridges are structures that are coherent in velocity and gravitationally bound, despite their large velocity dispersion measured by the N2H+ (1-0) lines of the W43-HERO IRAM large program. Another intriguing result is that these ridges harbor widespread (~10 pc2) bright SiO (2-1) emission, which we interpret to be the result of low-velocity shocks (models to demonstrate that a small percentage (10%) of Si atoms in low-velocity shocks, observed initially in gas phase or in grain mantles, can explain the observed SiO column density in the W43 ridges. The spatial and velocity overlaps between the ridges of high-density gas and the shocked SiO gas suggest that ridges could be forming via colliding flows driven by gravity and accompanied by low-velocity shocks. This mechanism may be the initial conditions for the formation of young massive clusters.

  14. SU-F-P-39: End-To-End Validation of a 6 MV High Dose Rate Photon Beam, Configured for Eclipse AAA Algorithm Using Golden Beam Data, for SBRT Treatments Using RapidArc

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, M; Salinas Aranda, F; Dodat, D; Sansogne, R; Arbiser, S [Vidt Centro Medico, Ciudad Autonoma De Buenos Aires, Ciudad Autonoma de Buenos Aire (Argentina)

    2016-06-15

    Purpose: To use end-to-end testing to validate a 6 MV high dose rate photon beam, configured for Eclipse AAA algorithm using Golden Beam Data (GBD), for SBRT treatments using RapidArc. Methods: Beam data was configured for Varian Eclipse AAA algorithm using the GBD provided by the vendor. Transverse and diagonals dose profiles, PDDs and output factors down to a field size of 2×2 cm2 were measured on a Varian Trilogy Linac and compared with GBD library using 2% 2mm 1D gamma analysis. The MLC transmission factor and dosimetric leaf gap were determined to characterize the MLC in Eclipse. Mechanical and dosimetric tests were performed combining different gantry rotation speeds, dose rates and leaf speeds to evaluate the delivery system performance according to VMAT accuracy requirements. An end-to-end test was implemented planning several SBRT RapidArc treatments on a CIRS 002LFC IMRT Thorax Phantom. The CT scanner calibration curve was acquired and loaded in Eclipse. PTW 31013 ionization chamber was used with Keithley 35617EBS electrometer for absolute point dose measurements in water and lung equivalent inserts. TPS calculated planar dose distributions were compared to those measured using EPID and MapCheck, as an independent verification method. Results were evaluated with gamma criteria of 2% dose difference and 2mm DTA for 95% of points. Results: GBD set vs. measured data passed 2% 2mm 1D gamma analysis even for small fields. Machine performance tests show results are independent of machine delivery configuration, as expected. Absolute point dosimetry comparison resulted within 4% for the worst case scenario in lung. Over 97% of the points evaluated in dose distributions passed gamma index analysis. Conclusion: Eclipse AAA algorithm configuration of the 6 MV high dose rate photon beam using GBD proved efficient. End-to-end test dose calculation results indicate it can be used clinically for SBRT using RapidArc.

  15. Laboratory reflectometer for the investigation of optical elements in a wavelength range of 5-50 nm: description and testing results

    Science.gov (United States)

    Garakhin, S. A.; Zabrodin, I. G.; Zuev, S. E.; Kas'kov, I. A.; Lopatin, A. Ya.; Nechay, A. N.; Polkovnikov, V. N.; Salashchenko, N. N.; Tsybin, N. N.; Chkhalo, N. I.; Svechnikov, M. V.

    2017-05-01

    We describe a laboratory reflectometer developed at the IPM RAS for precision measurements of spectral and angular dependences of the reflection and transmission coefficients of optical elements in a wavelength range of 5-50 nm. The radiation is monochromatised using a high-resolution Czerny-Turner spectrometer with a plane diffraction grating and two spherical collimating mirrors. A toroidal mirror focuses the probe monochromatic beam on a sample. The X-ray source is a highly ionised plasma produced in the interaction of a high-power laser beam with a solid target at an intensity of 1011-1012 W cm-2. To stabilise the emission characteristics, the target executes translatory and rotary motions in such a way that every pulse irradiates a new spot. The short-focus lens is protected from contamination by erosion products with the use of a specially designed electromagnetic system. The samples under study are mounted on a goniometer is accommodated in a dedicated chamber, which provides five degrees of freedom for samples up to 500 mm in diameter and two degrees of freedom for a detector. The sample mass may range up to 10 kg. The X-ray radiation is recorded with a detector composed of a CsI photocathode and two microchannel plates. A similar detector monitors the probe beam intensity. The spectral reflectometer resolution is equal to 0.030 nm with the use of ruled gratings with a density of 900 lines mm-1 (spectral range: 5-20 nm) and to 0.067 nm for holographic gratings with a density of 400 lines mm-1 (spectral range: 10-50 nm). We analyse the contribution of higher diffraction orders to the probe signal intensity and the ways of taking it into account in the measurements. Examples are given which serve to illustrate the reflectometer application to the study of multilayer mirrors and filters.

  16. Fiber-delivered mid-infrared (6-7) laser ablation of retinal tissue under perfluorodecalin

    Science.gov (United States)

    Mackanos, Mark A.; Joos, Karen M.; Jansen, E. Duco

    2003-07-01

    The Er:YAG laser (l=2.94mm) is an effective tool in vitreo-retinal surgery. Pulsed mid-infrared (l=6.45 mm) radiation from the Free Electron Laser has been touted as a potentially superior cutting tool. To date, use of this laser has been limited to applications in an air environment. The goal of this study was: 1) determine feasibility of fiberoptic delivery of 6.45mm using silverhalide fibers (d=700mm); 2) use infrared transparent vitreous substitute (perfluorodecalin) to allow non-contact ablation of the retina at 6.45mm. Fiber damage threshold=7.8J/cm2 (0.54GW/cm2) while transmission loss=0.54dB/m, allowing supra-ablative radiant exposures to the target. FTIR measurements of perfluorodecalin at 6.45mm yielded ma=3mm-1. Pump-probe imaging of ablation of a tissue-phantom through perfluorodecalin showed feasibility of non-contact ablation at l=6.45mm. Ablation of the retinal membranes of enucleated pig eyes was carried out under perfluorodecalin (5 Hz, 1.3 J/cm2). Each eye was cut along its equator to expose the retina. Vitreous was replaced by perfluorodecalin and laser radiation was delivered to the retina via the silverhalide fiber. The eye was rotated (at 2 rpm) using a stepper motor (0.9o/step) to create an ablation circle around the central axis of the retina (50% spot-to-spot overlap). Histological analysis of ablation yield and collateral damage will be presented. We have shown that using l=6.45mm delivered via silver halide fibers through perfluorodecalin allowed non-contact laser ablation. Remote structures are shielded, as the radiant exposure falls below the ablation threshold owing non-negligible absorption of perfluorodecalin at 6.45mm. This may optimize efficacy and safety of laser-based vitreoretinal surgery.

  17. Microarcsecond relative astrometry from the ground with a diffractive pupil

    Energy Technology Data Exchange (ETDEWEB)

    Ammons, S M; Bendek, E; Guyon, O

    2011-09-08

    The practical use of astrometry to detect exoplanets via the reflex motion of the parent star depends critically on the elimination of systematic floors in imaging systems. In the diffractive pupil technique proposed for space-based detection of exo-earths, extended diffraction spikes generated by a dotted primary mirror are referenced against a wide-field grid of background stars to calibrate changing optical distortion and achieve microarcsecond astrometric precision on bright targets (Guyon et al. 2010). We describe applications of this concept to ground-based uncrowded astrometry using a diffractive, monopupil telescope and a wide-field camera to image as many as {approx}4000 background reference stars. Final relative astrometric precision is limited by differential tip/tilt jitter caused by high altitude layers of turbulence. A diffractive 3-meter telescope is capable of reaching {approx}35 {micro}as relative astrometric error per coordinate perpendicular to the zenith vector in three hours on a bright target star (I < 10) in fields of moderate stellar density ({approx}40 stars arcmin{sup -2} with I < 23). Smaller diffractive apertures (D < 1 m) can achieve 100-200 {micro}as performance with the same stellar density and exposure time and a large telescope (6.5-10 m) could achieve as low as 10 {micro}as, nearly an order of magnitude better than current space-based facilities. The diffractive pupil enables the use of larger fields of view through calibration of changing optical distortion as well as brighter target stars (V < 6) by preventing star saturation. Permitting the sky to naturally roll to average signals over many thousands of pixels can mitigate the effects of detector imperfections.

  18. Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL.

    Science.gov (United States)

    Zhao, H W; Sun, L T; Zhang, X Z; Guo, X H; Cao, Y; Lu, W; Zhang, Z M; Yuan, P; Song, M T; Zhao, H Y; Jin, T; Shang, Y; Zhan, W L; Wei, B W; Xie, D Z

    2008-02-01

    There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e microA of O(7+), 505 e microA of Xe(20+), 306 e microA of Xe(27+), and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

  19. An electrochemical dopamine sensor based on the ZnO/CuO nanohybrid structures.

    Science.gov (United States)

    Khun, K; Ibupoto, Z H; Liu, X; Mansor, N A; Turner, A P F; Beni, V; Willander, M

    2014-09-01

    The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 μA mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

  20. Azadirachta indica plant-assisted green synthesis of Mn3O4 nanoparticles: Excellent thermal catalytic performance and chemical sensing behavior.

    Science.gov (United States)

    Sharma, Jitendra Kumar; Srivastava, Pratibha; Ameen, Sadia; Akhtar, M Shaheer; Singh, Gurdip; Yadava, Sudha

    2016-06-15

    The leaf extract of Azadirachta indica (Neem) plant was utilized as reducing agent for the green synthesis of Mn3O4 nanoparticles (NPs). The crystalline analysis demonstrated the typical tetragonal hausmannite crystal structure of Mn3O4, which confirmed the formation of Mn3O4 NPs without the existence of other oxides. Green synthesized Mn3O4 NPs were applied for the catalytic thermal decomposition of ammonium perchlorate (AP) and as working electrode for fabricating the chemical sensor. The excellent catalytic effect for the thermal decomposition of AP was observed by decreasing the decomposition temperature by 175 °C with single decomposing step. The fabricated chemical sensor based on green synthesized Mn3O4 NPs displayed high, reliable and reproducible sensitivity of ∼569.2 μA mM(-1) cm(-2) with reasonable limit of detection (LOD) of ∼22.1 μM and the response time of ∼10 s toward the detection of 2-butanone chemical. A relatively good linearity in the ranging from ∼20 to 160 μM was detected for Mn3O4 NPs electrode based 2-butanone chemical sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Direct electrochemistry of glucose oxidase assembled on graphene and application to glucose detection

    International Nuclear Information System (INIS)

    Wu Ping; Shao Qian; Hu Yaojuan; Jin Juan; Yin Yajing; Zhang Hui; Cai Chenxin

    2010-01-01

    The direct electrochemistry of glucose oxidase (GOx) integrated with graphene was investigated. The voltammetric results indicated that GOx assembled on graphene retained its native structure and bioactivity, exhibited a surface-confined process, and underwent effective direct electron transfer (DET) reaction with an apparent rate constant (k s ) of 2.68 s -1 . This work also developed a novel approach for glucose detection based on the electrocatalytic reduction of oxygen at the GOx-graphene/GC electrode. The assembled GOx could electrocatalyze the reduction of dissolved oxygen. Upon the addition of glucose, the reduction current decreased, which could be used for glucose detection with a high sensitivity (ca. 110 ± 3 μA mM -1 cm -2 ), a wide linear range (0.1-10 mM), and a low detection limit (10 ± 2 μM). The developed approach can efficiently exclude the interference of commonly coexisting electroactive species due to the use of a low detection potential (-470 mV, versus SCE). Therefore, this study has not only successfully achieved DET reaction of GOx assembled on graphene, but also established a novel approach for glucose detection and provided a general route for fabricating graphene-based biosensing platform via assembling enzymes/proteins on graphene surface.

  2. One-pot synthesis of NiO/Mn2O3 nanoflake arrays and their application in electrochemical biosensing

    Science.gov (United States)

    Wang, Yao; Cui, Jiewu; Luo, Lan; Zhang, Jingcheng; Wang, Yan; Qin, Yongqiang; Zhang, Yong; Shu, Xia; Lv, Jun; Wu, Yucheng

    2017-11-01

    The exploration of novel nanomaterials employed as substrate to construct glucose biosensors is still of significance in the field of clinical diagnosis. In this work, NiO/Mn2O3 nanoflake arrays were synthesized by hydrothermal approach in combination with calcination process. As-prepared NiO/Mn2O3 nanoflake arrays were utilized to construct electrochemical biosensors for glucose detection. NiO/Mn2O3 nanoflake arrays were investigated systematically by scanning electron microscopy (SEM), X-ray diffractionmeter (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy, the formation mechanism of NiO/Mn2O3 nanoflake arrays was proposed. As-prepared glucose biosensors based on NiO/Mn2O3 nanoflake arrays were characterized by cyclic voltammgrams and chronoamperometry. The results indicated that glucose biosensors based on optimized NiO/Mn2O3 nanoflake arrays exhibited a high sensitivity of 167.0 μA mM-1 Cm-2 and good anti-interference ability, suggesting the NiO/Mn2O3 nanoflake arrays are an attractive substrate for the construction of oxidase-based biosensors.

  3. Highly efficient biosensors by using well-ordered ZnO/ZnS core/shell nanotube arrays

    Science.gov (United States)

    Tarish, Samar; Xu, Yang; Wang, Zhijie; Mate, Faten; Al-Haddad, Ahmed; Wang, Wenxin; Lei, Yong

    2017-10-01

    We have studied the fabrication of highly efficient glucose sensors using well-ordered heterogeneous ZnO/ZnS core/shell nanotube arrays (CSNAs). The modified electrodes exhibit a superior electrochemical response towards ferrocyanide/ferricyanide and in glucose sensing. Further, the fabricated glucose biosensor exhibited good performance over an acceptable linear range from 2.39 × 10-5 to 2.66 × 10-4 mM, with a sensitivity of 188.34 mA mM-1 cm-2, which is higher than that of the ZnO nanotube array counterpart. A low limit of detection was realized (24 μM), which is good compared with electrodes based on conventional structures. In addition, the enhanced direct electrochemistry of glucose oxidase indicates the fast electron transfer of ZnO/ZnS CSNA electrodes, with a heterogeneous electron transfer rate constant (K s) of 1.69 s-1. The fast electron transfer is attributed to the high conductivity of the modified electrodes. The presented ZnS shell can facilitate the construction of future sensors and enhance the ZnO surface in a biological environment.

  4. Glucose biosensor based on glucose oxidase immobilized on a nanofilm composed of mesoporous hydroxyapatite, titanium dioxide, and modified with multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Li, J.; Kuang, D.; Feng, Y.; Zhang, F.; Liu, M.

    2012-01-01

    We report on a highly sensitive glucose biosensor that was fabricated from a composite made from mesoporous hydroxyapatite and mesoporous titanium dioxide which then were ultrasonically mixed with multi-walled carbon nanotubes to form a rough nanocomposite film. This film served as a platform to immobilize glucose oxidase onto a glassy carbon electrode. The morphological and electrochemical properties of the film were examined by scanning electron microscopy and electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometry were used to characterize the electrochemical performances of the biosensor which exhibited excellent electrocatalytic activity to the oxidation of glucose. At an operating potential of 0. 3 V and pH 6. 8, the sensor displays a sensitivity of 57. 0 μA mM -1 cm -2 , a response time of <5 s, a linear dynamic range from 0. 01 to 15. 2 mM, a correlation coefficient of 0. 9985, and a detection limit of 2 μM at an SNR of 3. No interferences are found for uric acid, ascorbic acid, dopamine and most carbohydrates. The sensor is stable and was successfully applied to the determination of glucose in real samples. (author)

  5. Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection.

    Science.gov (United States)

    Cui, Jiewu; Adeloju, Samuel B; Wu, Yucheng

    2014-01-27

    A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO(x)) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GO(x) nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm(-2) mM(-1) for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5-6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Effective immobilization of glucose oxidase on chitosan submicron particles from gladius of Todarodes pacificus for glucose sensing.

    Science.gov (United States)

    Anusha, J R; Fleming, Albin T; Kim, Hee-Je; Kim, Byung Chul; Yu, Kook-Hyun; Raj, C Justin

    2015-08-01

    An effective enzymatic glucose biosensor was developed by immobilizing glucose oxidase on chitosan submicron particles synthesized from the gladius of Todarodes pacificus (GCSP). The chemically synthesized chitosan from gladius was pulverized to submicron particles by ball milling technique, which was further characterized and compared with the standard chitosan (SCS). The degree of deacetylation of GCSP was determined using FTIR spectroscopy which was comparable to the value of standard chitosan. The glucose oxidase (GOx) was immobilized over GCSP on porous zinc oxide/platinum nanoparticle (ZnO/Pt) based electrode. The morphological and structural properties of the electrodes were analyzed using scanning electron microscopy and X-ray diffraction analysis. The glucose sensing behavior of electrode was estimated using electrochemical analysis and showed an excellent analytical performance. The electrode ZnO/Pt/GCSP conjugated with GOx displayed high sensitivity (88.76 μA mM(-1) cm(-2)) with low detection limit in short response time. In addition, the very low value of Michaelis-Menten constant for GCSP based electrode contributes a better affinity of the electrode surface towards glucose oxidase. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. A CuNi/C Nanosheet Array Based on a Metal-Organic Framework Derivate as a Supersensitive Non-Enzymatic Glucose Sensor

    Science.gov (United States)

    Zhang, Li; Ye, Chen; Li, Xu; Ding, Yaru; Liang, Hongbo; Zhao, Guangyu; Wang, Yan

    2018-06-01

    Bimetal catalysts are good alternatives for non-enzymatic glucose sensors owing to their low cost, high activity, good conductivity, and ease of fabrication. In the present study, a self-supported CuNi/C electrode prepared by electrodepositing Cu nanoparticles on a Ni-based metal-organic framework (MOF) derivate was used as a non-enzymatic glucose sensor. The porous construction and carbon scaffold inherited from the Ni-MOF guarantee good kinetics of the electrode process in electrochemical glucose detection. Furthermore, Cu nanoparticles disturb the array structure of MOF derived films and evidently enhance their electrochemical performances in glucose detection. Electrochemical measurements indicate that the CuNi/C electrode possesses a high sensitivity of 17.12 mA mM-1 cm-2, a low detection limit of 66.67 nM, and a wider linearity range from 0.20 to 2.72 mM. Additionally, the electrode exhibits good reusability, reproducibility, and stability, thereby catering to the practical use of glucose sensors. Similar values of glucose concentrations in human blood serum samples are detected with our electrode and with the method involving glucose-6-phosphate dehydrogenase; the results further demonstrate the practical feasibility of our electrode.

  8. Long-term Biosensors for Metabolite Monitoring by using Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Cristina BOERO

    2011-02-01

    Full Text Available The key-point for the development of an amperometric sensor is the immobilization of the enzyme. In the present work we use biosensors based on glucose oxidase (GOD onto electrodes nanostructured with carbon nanotubes (CNT, to be employed in cell culture monitoring. The goal is to determine the best immobilization strategy from the point-of-view of sensor lifetime. We compared three types of immobilization: the spontaneous adsorption of the enzyme on nanotubes, the entrapment in a Nafion matrix (optimizing also the quantity, and the cross-linking with glutaraldehyde. The cross-linking gives the best sensitivity, 17.38 µA mM-1 cm-2, and the lowest detection limit, 25 µM. On the other hand, Nafion matrix allows to extend the linear range up to 7.5 mM. Finally, electrodes are tested over 35 days to analyze the lifetime. GOD cross-linking results to have 100% of retained activity after 35 days, while the adsorption and the entrapment retain only the 20 % of the original response.

  9. Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

    International Nuclear Information System (INIS)

    Yu Jiuhong; Ju Huangxian

    2003-01-01

    Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H 2 O 2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H 2 O 2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM -1 cm -2 . The linear range for H 2 O 2 determination was from 5.0x10 -7 to 5.4x10 -5 M with a detection limit of 1.2x10 -7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated

  10. Evaluation of a New Biosensor Based on in Situ Synthesized PPy-Ag-PVP Nanohybrid for Selective Detection of Dopamine.

    Science.gov (United States)

    Vellaichamy, Balakumar; Periakaruppan, Prakash; Paulmony, Tharmaraj

    2017-02-09

    In the present work, in situ synthesis of polypyrrole-silver-polyvinylpyrrolidone (PPy-Ag-PVP) nanohybrid using AgNO 3 as an oxidant and polyvinylpyrrolidone (PVP) as a stabilizer and surfactant is demonstrated. The obtained ternary PPy-Ag-PVP nanohybrid was characterized by UV-vis, FT-IR, XRD, Raman, TGA, SEM, and HR-TEM analysis. Further the synthesized PPy-Ag-PVP has been investigated for its selective and sensitive sensing of dopamine (DA). The PPy-Ag-PVP modified glassy carbon electrode shows a reversible electrochemical behavior with superior response for DA. The limit of detection and limit of quantification are found to be 0.0126 and 0.042 μM (S/N = 3 and 10), respectively, with remarkable sensitivity (7.26 μA mM -1 cm -2 ). The practical application of the present modified electrode has been validated by determining the concentration of DA in human urine samples of different age group.

  11. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    Science.gov (United States)

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Science.gov (United States)

    Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S.

    2017-07-01

    Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM-1 cm-2 with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg-1 at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  13. Fe2Ni2N nanosheet array: an efficient non-noble-metal electrocatalyst for non-enzymatic glucose sensing

    Science.gov (United States)

    You, Chao; Dai, Rui; Cao, Xiaoqin; Ji, Yuyao; Qu, Fengli; Liu, Zhiang; Du, Gu; Asiri, Abdullah M.; Xiong, Xiaoli; Sun, Xuping; Huang, Ke

    2017-09-01

    It is very important to develop enhanced electrochemical sensing platforms for molecular detection and non-noble-metal nanoarray architecture, as electrochemical catalyst electrodes have attracted great attention due to their large specific surface area and easy accessibility to target molecules. In this paper, we demonstrate that an Fe2Ni2N nanosheet array grown on Ti mesh (Fe2Ni2N NS/TM) shows high electrocatalytic activity toward glucose electrooxidation in alkaline medium. As an electrochemical glucose sensor, such an Fe2Ni2N NS/TM catalyst electrode demonstrates superior sensing performance with a short response time of less than 5 s, a wide linear range of 0.05 μM-1.5 mM, a low detection limit of 0.038 μM (S/N = 3), a high sensitivity of 6250 μA mM-1 cm-2, as well as high selectivity and long-term stability.

  14. Amperometric hydrogen peroxide biosensor based on the immobilization of horseradish peroxidase on core-shell organosilica-chitosan nanospheres and multiwall carbon nanotubes composite

    International Nuclear Information System (INIS)

    Chen Shihong; Yuan Ruo; Chai Yaqin; Yin Bin; Li Wenjun; Min Ligen

    2009-01-01

    The application of the composites of multiwall carbon nanotubes (MWNTs) and core-shell organosilica-chitosan crosslinked nanospheres as an immobilization matrix for the construction of an amperometric hydrogen peroxide (H 2 O 2 ) biosensor was described. MWNTs and positively charged organosilica-chitosan nanospheres were dispersed in acetic acid solution (0.6 wt%) to achieve organosilica-chitosan/MWNTs composites, which were cast onto a glass carbon electrode (GCE) surface directly. And then, horseradish peroxidase (HRP), as a model enzyme, was immobilized onto it through electrostatic interaction between oppositely charged organosilica-chitosan nanospheres and HRP. The direct electron transfer of HRP was achieved at HRP/organosilica-chitosan/MWNTs/GCE, which exhibited excellent electrocatalytic activity for the reduction of H 2 O 2 . The catalysis currents increased linearly to H 2 O 2 concentration in a wide range of 7.0 x 10 -7 to 2.8 x 10 -3 M, with a sensitivity of 49.8 μA mM -1 cm -2 and with a detection limit of 2.5 x 10 -7 M at 3σ. A Michaelies-Menten constant K M app value was estimated to be 0.32 mM, indicating a high-catalytic activity of HRP. Moreover, the proposed biosensor displayed a rapid response to H 2 O 2 and possessed good stability and reproducibility. When used to detect H 2 O 2 concentration in disinfector samples and sterilized milks, respectively, it showed satisfactory results

  15. Three-Dimensional Porous Nickel Frameworks Anchored with Cross-Linked Ni(OH)2 Nanosheets as a Highly Sensitive Nonenzymatic Glucose Sensor.

    Science.gov (United States)

    Mao, Weiwei; He, Haiping; Sun, Pengcheng; Ye, Zhizhen; Huang, Jingyun

    2018-05-02

    A facile and scalable in situ microelectrolysis nanofabrication technique is developed for preparing cross-linked Ni(OH) 2 nanosheets on a novel three-dimensional porous nickel template (Ni(OH) 2 @3DPN). For the constructed template, the porogen of NaCl particles not only induces a self-limiting surficial hot corrosion to claim the "start engine stop" mechanism but also serves as the primary battery electrolyte to greatly accelerate the growth of Ni(OH) 2 . As far as we know, the microelectrolysis nanofabrication is superior to the other reported Ni(OH) 2 synthesis methods due to the mild condition (60 °C, 6 h, NaCl solution, ambient environment) and without any post-treatment. The integrated Ni(OH) 2 @3DPN electrode with a highly suitable microstructure and a porous architecture implies a potential application in electrochemistry. As a proof-of-concept demonstration, the electrode was employed for nonenzymatic glucose sensing, which exhibits an outstanding sensitivity of 2761.6 μA mM -1 cm -2 ranging from 0.46 to 2100 μM, a fast response, and a low detection limit. The microelectrolysis nanofabrication is a one-step, binder-free, entirely green, and therefore it has a distinct advantage to improve clean production and reduce energy consumption.

  16. Ni/CdS bifunctional Ti@TiO2 core-shell nanowire electrode for high-performance nonenzymatic glucose sensing.

    Science.gov (United States)

    Guo, Chunyan; Huo, Huanhuan; Han, Xu; Xu, Cailing; Li, Hulin

    2014-01-07

    In this work, a Ni/CdS bifunctional Ti@TiO2 core-shell nanowire electrode with excellent electrochemical sensing property was successfully constructed through a hydrothermal and electrodeposition method. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were employed to confirm the synthesis and characterize the morphology of the as-prepared samples. The results revealed that the CdS layer between Ni and TiO2 plays an important role in the uniform nucleation and the following growth of highly dispersive Ni nanoparticle on the Ti@TiO2 core-shell nanowire surface. The bifunctional nanostructured electrode was applied to construct an electrochemical nonenzymatic sensor for the reliable detection of glucose. Under optimized conditions, this nonenzymatic glucose sensor displayed a high sensitivity up to 1136.67 μA mM(-1) cm(-2), a wider liner range of 0.005-12 mM, and a lower detection limit of 0.35 μM for glucose oxidation. The high dispersity of Ni nanoparticles, combined with the anti-poisoning faculty against the intermediate derived from the self-cleaning ability of CdS under the photoexcitation, was considered to be responsible for these enhanced electrochemical performances. Importantly, favorable reproducibility and long-term performance were also obtained thanks to the robust frameworks. All these results indicate this novel electrode is a promising candidate for nonenzymatic glucose sensing.

  17. A sensor tip based on carbon nanotube-ink printed electrode for the dengue virus NS1 protein.

    Science.gov (United States)

    Dias, Ana Carolina M S; Gomes-Filho, Sérgio L R; Silva, Mízia M S; Dutra, Rosa F

    2013-06-15

    An immunosensor for the non-structural protein 1 (NS1) of the dengue virus based on carbon nanotube-screen printed electrodes (CNT-SPE) was successfully developed. A homogeneous mixture containing carboxylated carbon nanotubes was dispersed in carbon ink to prepare a screen printed working electrode. Anti-NS1 antibodies were covalently linked to CNT-SPE by an ethylenediamine film strategy. Amperometrical responses were generated at -0.5 V vs. Ag/AgCl by hydrogen peroxide reaction with peroxidase (HRP) conjugated to the anti-NS1. An excellent detection limit (in the order of 12 ng mL(-1)) and a sensitivity of 85.59 μA mM(-1)cm(-2) were achieved permitting dengue diagnostic according to the clinical range required. The matrix effect, as well as the performance of the assays, was successfully evaluated using spiked blood serum sample obtaining excellent recovery values in the results. Carbon nanotubes incorporated to the carbon ink improved the reproducibility and sensitivity of the CNT-SPE immunosensor. This point-of-care approach represents a great potential value for use in epidemic situations and can facilitate the early screening of patients in acute phase of dengue virus. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

    International Nuclear Information System (INIS)

    Shi, Jin; Jaroch, David; Rickus, Jenna L; Marshall Porterfield, D; Claussen, Jonathan C; Ul Haque, Aeraj; Diggs, Alfred R; McLamore, Eric S; Calvo-Marzal, Percy

    2011-01-01

    This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an accurate indicator of biosensor efficacy, due to the wide range of electrodes and nanomaterials available for use in current biosensor designs. We proposed a comparative protocol which considers both the active area available for transduction following nanomaterial deposition and the sensitivity. Based on the protocol, when no nanomaterials were involved, TEOS/GOx biosensors exhibited the highest efficacy, followed by BSA/GA/GOx and TMOS/GOx biosensors. A novel biosensor containing carboxylated MWNTs modified with glucose oxidase and an overlying TMOS layer demonstrated optimum efficacy in terms of enhanced current density (18.3 ± 0.5 μA mM -1 cm -2 ), linear range (0.0037-12 mM), detection limit (3.7 μM), coefficient of variation (2%), response time (less than 8 s), and stability/selectivity/reproducibility. H 2 O 2 response tests demonstrated that the most possible reason for the performance enhancement was an increased enzyme loading. This design is an excellent platform for versatile biosensing applications.

  19. A novel tyrosinase biosensor based on hydroxyapatite-chitosan nanocomposite for the detection of phenolic compounds

    International Nuclear Information System (INIS)

    Lu Limin; Zhang Li; Zhang Xiaobing; Huan Shuangyan; Shen Guoli; Yu Ruqin

    2010-01-01

    A novel tyrosinase biosensor based on hydroxyapatite nanoparticles (nano-HA)-chitosan nanocomposite has been developed for the detection of phenolic compounds. The uniform and size controlled nano-HA was synthesized by hydrothermal method, and its morphological characterization was examined by transmission electron microscope (TEM). Tyrosinase was then immobilized on a nano-HA-chitosan nanocomposite-modified gold electrode. Electrochemical impedance spectroscopy and cyclic voltammetry were used to characterize the sensing film. The prepared biosensor was applied to determine phenolic compounds by monitoring the reduction signal of the biocatalytically produced quinone species at -0.2 V (vs. saturated calomel electrode). The effects of the pH, temperature and applied potential on the biosensor performance were investigated, and experimental conditions were optimized. The biosensor exhibited a linear response to catechol over a wide concentration range from 10 nM to 7 μM, with a high sensitivity of 2.11 x 10 3 μA mM -1 cm -2 , and a limit of detection down to 5 nM (based on S/N = 3). The apparent Michaelis-Menten constants of the enzyme electrode were estimated to be 3.16, 1.31 and 3.52 μM for catechol, phenol and m-cresol, respectively. Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.

  20. A lactate electrochemical biosensor with a titanate nanotube as direct electron transfer promoter

    International Nuclear Information System (INIS)

    Yang Mingli; Wang Jin; Li Huaqing; Wu Nianqiang Nick; Zheng Jianguo

    2008-01-01

    Hydrogen titanate (H 2 Ti 3 O 7 ) nanotubes (TNTs) have been synthesized by a one-step hydrothermal processing. Lactate oxidase (LOx) enzyme has been immobilized on the three-dimensional porous TNT network to make an electrochemical biosensor for lactate detection. Cyclic voltammetry and amperometry tests reveal that the LOx enzyme, which is supported on TNTs, maintains their substrate-specific catalytic activity. The nanotubes offer the pathway for direct electron transfer between the electrode surface and the active redox centers of LOx, which enables the biosensor to operate at a low working potential and to avoid the influence of the presence of O 2 on the amperometric current response. The biosensor exhibits a sensitivity of 0.24 μA cm -2 mM -1 , a 90% response time of 5 s, and a linear response in the range from 0.5 to 14 mM and the redox center of enzyme obviates the need of redox mediators for electrochemical enzymatic sensors, which is attractive for the development of reagentless biosensors

  1. Ammonium ions determination with polypyrrole modified electrode

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Dall´Antonia

    2007-03-01

    Full Text Available The present work relates the preparation of polypyrrole films (PPy deposited on surfaces of glass carbon, nickel and ITO (tin oxide doped with indium on PET plastic, in order to study the ammonium detection. The popypyrrole films were polymerized with dodecylbenzenesulfonate (DBSA on the electrodes, at + 0,70 V vs. Ag/AgCl, based on a solution containing the pyrrole monomer and the amphiphilic salt. Films deposited on glass carbon presented better performance. Cyclic voltammetries, between – 1,50 to + 0,5 V vs. Ag/AgCl, were repeated adding different concentrations of NH4Cl, in order to observe the behavior of the film as a possible detector of ions NH4+. The peak current for oxidation varies with the concentration of ammonium. A linear region can be observed in the band of 0 to 80 mM, with a sensibility (Sppy approximately similar to 4,2 mA mM-1 cm-2, showing the efficacy of the electrodes as sensors of ammonium ions. The amount of deposited polymer, controlled by the time of growth, does not influence on the sensor sensibility. The modified electrode was used to determine ammonium in grounded waters.

  2. Skin-Attachable, Stretchable Electrochemical Sweat Sensor for Glucose and pH Detection.

    Science.gov (United States)

    Oh, Seung Yun; Hong, Soo Yeong; Jeong, Yu Ra; Yun, Junyeong; Park, Heun; Jin, Sang Woo; Lee, Geumbee; Oh, Ju Hyun; Lee, Hanchan; Lee, Sang-Soo; Ha, Jeong Sook

    2018-04-25

    As part of increased efforts to develop wearable healthcare devices for monitoring and managing physiological and metabolic information, stretchable electrochemical sweat sensors have been investigated. In this study, we report on the fabrication of a stretchable and skin-attachable electrochemical sensor for detecting glucose and pH in sweat. A patterned stretchable electrode was fabricated via layer-by-layer deposition of carbon nanotubes (CNTs) on top of patterned Au nanosheets (AuNS) prepared by filtration onto stretchable substrate. For the detection of glucose and pH, CoWO 4 /CNT and polyaniline/CNT nanocomposites were coated onto the CNT-AuNS electrodes, respectively. A reference electrode was prepared via chlorination of silver nanowires. Encapsulation of the stretchable sensor with sticky silbione led to a skin-attachable sweat sensor. Our sensor showed high performance with sensitivities of 10.89 μA mM -1 cm -2 and 71.44 mV pH -1 for glucose and pH, respectively, with mechanical stability up to 30% stretching and air stability for 10 days. The sensor also showed good adhesion even to wet skin, allowing the detection of glucose and pH in sweat from running while being attached onto the skin. This work suggests the application of our stretchable and skin-attachable electrochemical sensor to health management as a high-performance healthcare wearable device.

  3. Porous HKUST-1 derived CuO/Cu2O shell wrapped Cu(OH)2 derived CuO/Cu2O core nanowire arrays for electrochemical nonenzymatic glucose sensors with ultrahigh sensitivity

    Science.gov (United States)

    Yu, Cuiping; Cui, Jiewu; Wang, Yan; Zheng, Hongmei; Zhang, Jianfang; Shu, Xia; Liu, Jiaqin; Zhang, Yong; Wu, Yucheng

    2018-05-01

    Self-supported CuO/Cu2O@CuO/Cu2O core-shell nanowire arrays (NWAs) are successfully fabricated by a simple and efficient method in this paper. Anodized Cu(OH)2 NWAs could in-situ convert to HKUST-1 at room temperature easily. Cu(OH)2 NWAs cores and HKUST-1 shells transform into CuO/Cu2O simultaneously after calcinations and form CuO/Cu2O@CuO/Cu2O core-shell NWAs. This smart configuration of the core-shell structure not only avoids the agglomeration of the traditional MOF-derived materials in particle-shape, but also facilitates the ion diffusion and increases the active sites. This novel structure is employed as substrate to construct nonenzymatic glucose sensors. The results indicate that glucose sensor based on CuO/Cu2O@CuO/Cu2O core-shell NWAs presents ultrahigh sensitivity (10,090 μA mM-1 cm-2), low detection limit (0.48 μM) and wide linear range (0.99-1,330 μM). In addition, it also shows excellent anti-interference ability toward uric acid, ascorbic acid and L-Cysteine co-existing with glucose, good reproducibility and superior ability of real sample analysis.

  4. Hollow mesoporous CuCo2O4 microspheres derived from metal organic framework: A novel functional materials for simultaneous H2O2 biosensing and glucose biofuel cell.

    Science.gov (United States)

    Cui, Shiqiang; Gu, Shuqing; Ding, Yaping; Zhang, Jiangjiang; Zhang, Zhen; Hu, Zongqian

    2018-02-01

    Hollow mesoporous CuCo 2 O 4 (meso-CuCo 2 O 4 ) microspheres were successfully synthesized by decomposing metal-organic frameworks (MOFs) as the template. The as-prepared CuCo 2 O 4 microspheres were first simultaneously used for H 2 O 2 biosensing and glucose biofuel cell (GFC) as the enzyme mimic. The resulting of meso-CuCo 2 O 4 displayed not only excellent catalytic performances to H 2 O 2 including a super-fast response time (within 2s), a super-high sensitivity (654.23 μA mM -1 cm -2 ) and a super-low detection limit (3nM at S/N = 3) on the sensor, but also great values in GFC as anode material with an open circuit voltage of 0.85V, a maximum power density of 0.33 mWcm -2 and a limiting current density of 1.27 mAcm -2 , respectively. The preeminent catalytic abilities to H 2 O 2 and glucose may be attributed to the surpassing intrinsic catalytic activity of CuCo 2 O 4 and large specific area of mesoporous structure. These significant findings deriving from this work not only provided a novel exploration for the fabrication of hollow spherical mesoporous bimetallic oxides, but also promoted the development of the supersensitive detection of H 2 O 2 and non-enzymatic biofuel cell. Copyright © 2017. Published by Elsevier B.V.

  5. Immobilization of Glucose Oxidase on Modified-Carbon-Paste-Electrodes for Microfuel Cell

    Directory of Open Access Journals (Sweden)

    Laksmi Ambarsari

    2016-03-01

    Full Text Available Glucose oxidase (GOx is being developed for many applications such as an implantable fuel cell, due to its attractive property of operating under physiological conditions. This study reports the functional immobilization of glucose oxidase onto polyaniline-nanofiber-modified-carbon-paste-electrodes (GOx/MCPE as bioanodes in fuel cell applications. In particular, GOx is immobilized onto the electrode surface via a linker molecule (glutaraldehyde. Polyaniline, synthesized by the interfacial polymerization method, produces a morphological form of nanofibers (100-120 nm which have good conductivity. The performance of the polyaniline-modified-carbon-paste-electrode (MCPE was better than the carbon- paste-electrode (CPE alone. The optimal pH and temperature of the GOx/MCPE were 4.5 (in 100 mM acetate buffer and 65 °C, respectively. The GOx/MCPE exhibit high catalytic performances (activation energy 16.4 kJ mol-1, have a high affinity for glucose (Km value 37.79 µM and can have a maximum current (Imax of 3.95 mA. The sensitivity of the bioelectrode also was high at 57.79 mA mM-1 cm-2.

  6. Co3O4 based non-enzymatic glucose sensor with high sensitivity and reliable stability derived from hollow hierarchical architecture

    Science.gov (United States)

    Tian, Liangliang; He, Gege; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Yang, Cong; Chen, Yanling; Li, Lu

    2018-02-01

    Inspired by kinetics, the design of hollow hierarchical electrocatalysts through large-scale integration of building blocks is recognized as an effective approach to the achievement of superior electrocatalytic performance. In this work, a hollow, hierarchical Co3O4 architecture (Co3O4 HHA) was constructed using a coordinated etching and precipitation (CEP) method followed by calcination. The resulting Co3O4 HHA electrode exhibited excellent electrocatalytic activity in terms of high sensitivity (839.3 μA mM-1 cm-2) and reliable stability in glucose detection. The high sensitivity could be attributed to the large specific surface area (SSA), ample unimpeded penetration diffusion paths and high electron transfer rate originating from the unique two-dimensional (2D) sheet-like character and hollow porous architecture. The hollow hierarchical structure also affords sufficient interspace for accommodation of volume change and structural strain, resulting in enhanced stability. The results indicate that Co3O4 HHA could have potential for application in the design of non-enzymatic glucose sensors, and that the construction of hollow hierarchical architecture provides an efficient way to design highly active, stable electrocatalysts.

  7. 3-D periodic mesoporous nickel oxide for nonenzymatic uric acid sensors with improved sensitivity

    Science.gov (United States)

    Huang, Wei; Cao, Yang; Chen, Yong; Zhou, Yang; Huang, Qingyou

    2015-12-01

    3-D periodic mesoporous nickel oxide (NiO) particles with crystalline walls have been synthesized through the microwave-assisted hard template route toward the KIT-6 silica. It was investigated as a nonenzymatic amperometric sensor for the detection of uric acid. 3-D periodic nickel oxide matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline nickel oxide belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and transmission electron microscopy (TEM). The analysis results showed that the microwave-assisted mesoporous NiO materials were more appropriate to be electrochemical sensors than the traditional mesoporous NiO. Cyclic voltammetry (CV) revealed that 3-D periodic NiO exhibited a direct electrocatalytic activity for the oxidation of uric acid in sodium hydroxide solution. The enzyme-less amperometric sensor used in the detection of uric acid with detection limit of 0.005 μM (S/N = 3) over wide linear detection ranges up to 0.374 mM and with a high sensitivity of 756.26 μA mM-1 cm-2, and a possible mechanism was also given in the paper.

  8. Carbon nanotubes-functionalized urchin-like In2S3 nanostructure for sensitive and selective electrochemical sensing of dopamine

    International Nuclear Information System (INIS)

    Yang, Z.; Huang, X.; Li, J.; Zhang, Y.; Yu, S.; Xu, Q.; Hu, X.

    2012-01-01

    Urchin-like In 2 S 3 nanostructures were functionalized with multi-walled carbon nanotubes (MWCNTs) and deposited on a glassy carbon electrode (GCE) to obtain a new kind of sensor for dopamine (DA). The new electrode was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry and differential pulse voltammetry. It is found that the current response toward DA is significantly enhanced compared to that of a bare GCE or a GCE modified with MWCNTs. The peak separation between DA and ascorbic acid (AA) is up to 225 mV. The new electrode also has improved selectivity for DA over AA compared to the bare electrode. The new DA sensor has a wide linear range (0.5-300 μM), high sensitivity (594.9 μA mM -1 cm -2 ) and low detection limit (0.1 μM). CNTs wrapped on urchin-like nanostructures remarkable improve its electrocatalytic activity and thus provide a promising strategy to develop excellent composite materials for electrochemical sensing. (author)

  9. Palladium nanoparticles deposited on graphene and its electrochemical performance for glucose sensing

    Science.gov (United States)

    Mijowska, Ewa; Onyszko, Magdalena; Urbas, Karolina; Aleksandrzak, Malgorzata; Shi, Xiaoze; Moszyński, Dariusz; Penkala, Krzysztof; Podolski, Jacek; El Fray, Mirosława

    2015-11-01

    This paper reports on the fabrication and characterization of glucose oxidase (GOx) immobilized onto a glassy carbon electrode (GCE) modified with reduced graphene oxide/palladium nanocomposite (RGO-Pd). Characterization tools showed well dispersed uniform Pd nanoparticles on a partly reduced graphene oxide surface. Cyclic voltammetry demonstrated successful immobilization of GOx on RGO-Pd modified GCE (GCE-RGO-Pd) using covalent bonding of GOx with RGO-Pd (RGO-Pd-GOx). Therefore, it was used as an electrochemical biosensor of glucose. RGO-Pd-GOx exhibited good electrocatalysis toward glucose in different glucose concentrations (from 2 to 10 mM, which includes the blood glucose levels of both normal and diabetic persons) with O2 saturated phosphate buffer solution (PBS) at pH 7.4. The system showed a linear increase in current at potential -0.085 V in the concentration range examined, with a correlation coefficient of 0.996. The sensitivity of the biosensor was 41.3 μA cm-2 mM-1, suggesting that RGO-Pd-GOx-modified GCE could be a potential candidate as a glucose sensor.

  10. A nanoporous ruthenium oxide framework for amperometric sensing of glucose and potentiometric sensing of pH

    International Nuclear Information System (INIS)

    Shim, J.H.; Kang, M.; Lee, Y.; Lee, C.

    2012-01-01

    Nanoporous ruthenium oxide frameworks (L 2 -eRuO) were electrodeposited on gold substrates by repetitive potential cycling in solutions of ruthenium(III) ions in the presence of reverse neutral micelles. The L 2 -eRuO was characterized in terms of direct oxidation of glucose and potentiometric response to pH values. The surface structures and morphologies of the L 2 -eRuO were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. Their surface area was estimated via underpotential deposition of copper. L 2-eRuO-modified electrodes showed a 17-fold higher sensitivity (40 μA mM -1 cm -2 towards glucose in 0-4 mM concentration in solution of pH 7.4) than a RuO electrode prepared in the absence of reverse micelles. Potential interferents such as ascorbic acid, 4-acetamidophenol, uric acid and dopamine displayed no effect. The new electrode also revealed improved potentiometric response to pH changes compared to a platinum electrode of the same type. (author)

  11. 2000W high beam quality diode laser for direct materials processing

    Science.gov (United States)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

    2011-11-01

    This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

  12. A highly efficient microfluidic nano biochip based on nanostructured nickel oxide.

    Science.gov (United States)

    Ali, Md Azahar; Solanki, Pratima R; Patel, Manoj K; Dhayani, Hemant; Agrawal, Ved Varun; John, Renu; Malhotra, Bansi D

    2013-04-07

    We present results of the studies relating to fabrication of a microfluidic biosensor chip based on nickel oxide nanorods (NRs-NiO) that is capable of directly measuring the concentration of total cholesterol in human blood through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of cholesterol present in buffer solutions at clinically relevant concentrations. The microfluidic channel has been fabricated onto a nickel oxide nanorod-based electrode co-immobilized with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) that serves as the working electrode. Bare indium tin oxide served as the counter electrode. A Ag/AgCl wire introduced to the outlet of the microchannel acts as a reference electrode. The fabricated NiO nanorod-based electrode has been characterized using X-ray diffraction, Raman spectroscopy, HR-TEM, FT-IR, UV-visible spectroscopy and electrochemical techniques. The presented NRs-NiO based microfluidic sensor exhibits linearity in the range of 1.5-10.3 mM, a high sensitivity of 0.12 mA mM(-1) cm(-2) and a low value of 0.16 mM of the Michaelis-Menten constant (Km).

  13. Sensitive Nonenzymatic Electrochemical Glucose Detection Based on Hollow Porous NiO

    Science.gov (United States)

    He, Gege; Tian, Liangliang; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Pu, Wanrong; Zhang, Jinkun; Li, Lu

    2018-01-01

    Transition metal oxides (TMOs) have attracted extensive research attentions as promising electrocatalytic materials. Despite low cost and high stability, the electrocatalytic activity of TMOs still cannot satisfy the requirements of applications. Inspired by kinetics, the design of hollow porous structure is considered as a promising strategy to achieve superior electrocatalytic performance. In this work, cubic NiO hollow porous architecture (NiO HPA) was constructed through coordinating etching and precipitating (CEP) principle followed by post calcination. Being employed to detect glucose, NiO HPA electrode exhibits outstanding electrocatalytic activity in terms of high sensitivity (1323 μA mM-1 cm-2) and low detection limit (0.32 μM). The excellent electrocatalytic activity can be ascribed to large specific surface area (SSA), ordered diffusion channels, and accelerated electron transfer rate derived from the unique hollow porous features. The results demonstrate that the NiO HPA could have practical applications in the design of nonenzymatic glucose sensors. The construction of hollow porous architecture provides an effective nanoengineering strategy for high-performance electrocatalysts.

  14. A novel CuO-N-doped graphene nanocomposite-based hybrid electrode for the electrochemical detection of glucose

    Science.gov (United States)

    Felix, Sathiyanathan; Kollu, Pratap; Jeong, Soon Kwan; Grace, Andrews Nirmala

    2017-10-01

    We report a catalyst of N-doped graphene CuO nanocomposite, for the non-enzymatic electrocatalytic oxidation of glucose. The hybrid nanocomposite was synthesized by copper sulfate, cetyl ammonium bromide and graphite as starting materials. The synthesized composites were characterized with the techniques like X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope to study the crystalline phase and morphological structure. Based on this composite, a non-enzymatic glucose sensor was constructed. Cyclic voltammetry and chronoamperometry methods were done to investigate the electrocatalytic properties of glucose in alkaline medium. For glucose detection, the fabricated sensor showed a linear response over a wide range of concentration from 3 to 1000 µM, with sensitivity of 2365.7 µA mM-1 cm-2 and a fast response time of 5 s. The designed sensor exhibited negligible current response to the normal concentration of common interferents in the presence of glucose. All these favorable advantages of the fabricated glucose sensor suggest that it may have good potential application in biological samples, food and other related areas.

  15. A biopolymer-based carbon nanotube interface integrated with a redox shuttle and a D-sorbitol dehydrogenase for robust monitoring of D-sorbitol

    International Nuclear Information System (INIS)

    Sefcovicova, J.; Filip, J.; Gemeiner, P.; Bucko, M.; Magdolen, P.; Tkac, J.; Tomcik, P.

    2011-01-01

    We describe the preparation and characterization of a glassy carbon electrode modified with a bionanocomposite consisting of a hyaluronic acid, dispersed carbon nanotubes, and electrostatically bound toluidine blue. The electrode was used to detect NADH in the batch and flow-injection mode of operation. The electrode was further modified by immobilizing sorbitol dehydrogenase to result in biosensor for D-sorbitol that displays good operational stability, a sensitivity of 10.6 μA mM -1 cm -2 , a response time of 16 s, and detection limit in the low micromolar range. The biosensor was successfully applied to off-line monitoring of D-sorbitol during its bioconversion into L-sorbose (a precursor in the synthesis of vitamin C) by Gluconobacter oxydans. The sample assay precision is 2.5% (an average RSD) and the throughput is 65 h -1 if operated in the flow-injection mode. The validation of this biosensor against a reference HPLC method resulted in a slope of correlation of 1.021 ± 0.001 (R 2 = 0.99997). (author)

  16. Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

    Science.gov (United States)

    Mao, Feng; Ong, Say Kee; Gaunt, James A

    2015-09-01

    Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

  17. A new self-assembled layer-by-layer glucose biosensor based on chitosan biopolymer entrapped enzyme with nitrogen doped graphene.

    Science.gov (United States)

    Barsan, Madalina M; David, Melinda; Florescu, Monica; Ţugulea, Laura; Brett, Christopher M A

    2014-10-01

    The layer-by-layer (LbL) technique has been used for the construction of a new enzyme biosensor. Multilayer films containing glucose oxidase, GOx, and nitrogen-doped graphene (NG) dispersed in the biocompatible positively-charged polymer chitosan (chit(+)(NG+GOx)), together with the negatively charged polymer poly(styrene sulfonate), PSS(-), were assembled by alternately immersing a gold electrode substrate in chit(+)(NG+GOx) and PSS(-) solutions. Gravimetric monitoring during LbL assembly by an electrochemical quartz microbalance enabled investigation of the adsorption mechanism and deposited mass for each monolayer. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the LbL modified electrodes, in order to establish the contribution of each monolayer to the overall electrochemical properties of the biosensor. The importance of NG in the biosensor architecture was evaluated by undertaking a comparative study without NG in the chit layer. The GOx biosensor's analytical properties were evaluated by fixed potential chronoamperometry and compared with similar reported biosensors. The biosensor operates at a low potential of -0.2V vs., Ag/AgCl, exhibiting a high sensitivity of 10.5 μA cm(-2) mM(-1), and a detection limit of 64 μM. This study shows a simple approach in developing new biosensor architectures, combining the advantages of nitrogen-doped graphene with the LbL technique for enzyme immobilization. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Enhanced sensitivity in non-enzymatic glucose detection by improved growth kinetics of Ni-based nanostructures

    Science.gov (United States)

    Urso, M.; Pellegrino, G.; Strano, V.; Bruno, E.; Priolo, F.; Mirabella, S.

    2018-04-01

    Ni-based nanostructures are attractive catalytic materials for many electrochemical applications, among which are non-enzymatic sensing, charge storage, and water splitting. In this work, we clarify the synthesis kinetics of Ni(OH)2/NiOOH nanowalls grown by chemical bath deposition at room temperature and at 50 °C. We applied the results to non-enzymatic glucose sensing, reaching a highest sensitivity of 31 mA cm-2mM-1. Using scanning electron microscopy, x-ray diffraction analysis and Rutherford backscattering spectrometry we found that the growth occurs through two regimes: first, a quick random growth leading to disordered sheets of Ni oxy-hydroxide, followed by a slower growth of well-aligned sheets of Ni hydroxide. A high growth temperature (50 °C), leading mainly to well-aligned sheets, offers superior electrochemical properties in terms of charge storage, charge carrier transport and catalytic action, as confirmed by cyclic voltammetry and electrochemical impedance spectroscopy analyses. The reported results on the optimization and application of low-cost synthesis of these Ni-based nanostructures have a large potential for application in catalysis, (bio)sensing, and supercapacitors areas.

  19. A lactate electrochemical biosensor with a titanate nanotube as direct electron transfer promoter

    Science.gov (United States)

    Yang, Mingli; Wang, Jin; Li, Huaqing; Zheng, Jian-Guo; Wu, Nianqiang Nick

    2008-02-01

    Hydrogen titanate (H2Ti3O7) nanotubes (TNTs) have been synthesized by a one-step hydrothermal processing. Lactate oxidase (LOx) enzyme has been immobilized on the three-dimensional porous TNT network to make an electrochemical biosensor for lactate detection. Cyclic voltammetry and amperometry tests reveal that the LOx enzyme, which is supported on TNTs, maintains their substrate-specific catalytic activity. The nanotubes offer the pathway for direct electron transfer between the electrode surface and the active redox centers of LOx, which enables the biosensor to operate at a low working potential and to avoid the influence of the presence of O2 on the amperometric current response. The biosensor exhibits a sensitivity of 0.24 µA cm-2 mM-1, a 90% response time of 5 s, and a linear response in the range from 0.5 to 14 mM and the redox center of enzyme obviates the need of redox mediators for electrochemical enzymatic sensors, which is attractive for the development of reagentless biosensors.

  20. A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

    Science.gov (United States)

    Shi, Jin; Claussen, Jonathan C.; McLamore, Eric S.; Haque, Aeraj ul; Jaroch, David; Diggs, Alfred R.; Calvo-Marzal, Percy; Rickus, Jenna L.; Porterfield, D. Marshall

    2011-09-01

    This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an accurate indicator of biosensor efficacy, due to the wide range of electrodes and nanomaterials available for use in current biosensor designs. We proposed a comparative protocol which considers both the active area available for transduction following nanomaterial deposition and the sensitivity. Based on the protocol, when no nanomaterials were involved, TEOS/GOx biosensors exhibited the highest efficacy, followed by BSA/GA/GOx and TMOS/GOx biosensors. A novel biosensor containing carboxylated MWNTs modified with glucose oxidase and an overlying TMOS layer demonstrated optimum efficacy in terms of enhanced current density (18.3 ± 0.5 µA mM - 1 cm - 2), linear range (0.0037-12 mM), detection limit (3.7 µM), coefficient of variation (2%), response time (less than 8 s), and stability/selectivity/reproducibility. H2O2 response tests demonstrated that the most possible reason for the performance enhancement was an increased enzyme loading. This design is an excellent platform for versatile biosensing applications.

  1. Direct patterning of gold nanoparticles using flexographic printing for biosensing applications

    Science.gov (United States)

    Benson, Jamie; Fung, Chung Man; Lloyd, Jonathan Stephen; Deganello, Davide; Smith, Nathan Andrew; Teng, Kar Seng

    2015-03-01

    In this paper, we have presented the use of flexographic printing techniques in the selective patterning of gold nanoparticles (AuNPs) onto a substrate. Highly uniform coverage of AuNPs was selectively patterned on the substrate surface, which was subsequently used in the development of a glucose sensor. These AuNPs provide a biocompatible site for the attachment of enzymes and offer high sensitivity in the detection of glucose due to their large surface to volume ratio. The average size of the printed AuNPs is less than 60 nm. Glucose sensing tests were performed using printed carbon-AuNP electrodes functionalized with glucose oxidase (GOx). The results showed a high sensitivity of 5.52 μA mM-1 cm-2 with a detection limit of 26 μM. We have demonstrated the fabrication of AuNP-based biosensors using flexographic printing, which is ideal for low-cost, high-volume production of the devices.

  2. Electrodeposition of gold-platinum alloy nanoparticles on ionic liquid-chitosan composite film and its application in fabricating an amperometric cholesterol biosensor.

    Science.gov (United States)

    Safavi, Afsaneh; Farjami, Fatemeh

    2011-01-15

    An electrodeposition method was applied to form gold-platinum (AuPt) alloy nanoparticles on the glassy carbon electrode (GCE) modified with a mixture of an ionic liquid (IL) and chitosan (Ch) (AuPt-Ch-IL/GCE). AuPt nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. AuPt-Ch-IL/GCE electrocatalyzed the reduction of H(2)O(2) and thus was suitable for the preparation of biosensors. Cholesterol oxidase (ChOx) was then, immobilized on the surface of the electrode by cross-linking ChOx and chitosan through addition of glutaraldehyde (ChOx/AuPt-Ch-IL/GCE). The fabricated biosensor exhibited two wide linear ranges of responses to cholesterol in the concentration ranges of 0.05-6.2 mM and 6.2-11.2 mM. The sensitivity of the biosensor was 90.7 μA mM(-1) cm(-2) and the limit of detection was 10 μM of cholesterol. The response time was less than 7 s. The Michaelis-Menten constant (K(m)) was found as 0.24 mM. The effect of the addition of 1 mM ascorbic acid and glucose was tested on the amperometric response of 0.5 mM cholesterol and no change in response current of cholesterol was observed. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Amperometric cholesterol biosensor based on the direct electrochemistry of cholesterol oxidase and catalase on a graphene/ionic liquid-modified glassy carbon electrode.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Khodadadian, Mehdi

    2014-03-15

    Cholesterol oxidase (ChOx) and catalase (CAT) were co-immobilized on a graphene/ionic liquid-modified glassy carbon electrode (GR-IL/GCE) to develop a highly sensitive amperometric cholesterol biosensor. The H2O2 generated during the enzymatic reaction of ChOx with cholesterol could be reduced electrocatalytically by immobilized CAT to obtain a sensitive amperometric response to cholesterol. The direct electron transfer between enzymes and electrode surface was investigated by cyclic voltammetry. Both enzymes showed well-defined redox peaks with quasi-reversible behaviors. An excellent sensitivity of 4.163 mA mM(-1)cm(-2), a response time less than 6s, and a linear range of 0.25-215 μM (R(2)>0.99) have been observed for cholesterol determination using the proposed biosensor. The apparent Michaelis-Menten constant (KM(app)) was calculated to be 2.32 mM. The bienzymatic cholesterol biosensor showed good reproducibility (RSDsascorbic acid and uric acid. The CAT/ChOx/GR-IL/GCE showed excellent analytical performance for the determination of free cholesterol in human serum samples. © 2013 Elsevier B.V. All rights reserved.

  4. A high performance non-enzymatic glucose sensor based on nickel hydroxide modified nitrogen-incorporated nanodiamonds.

    Science.gov (United States)

    Ko, Chih-Yu; Huang, Jin-Hua; Raina, Supil; Kang, Weng P

    2013-06-07

    A highly selective, sensitive, and stable non-enzymatic glucose sensor based on Ni hydroxide modified nitrogen-incorporated nanodiamonds (Ni(OH)2-NND) was developed. The sensor was fabricated by e-beam evaporation of a thin Ni film on NND followed by the growth of Ni(OH)2 using an electrochemical process. It was found that the Ni film thickness greatly affects the morphology and electro-catalytic activity of the as-synthesized electrode for non-enzymatic glucose oxidation. Owing to its nanostructure characteristics, the best sensor fabricated by 150 nm Ni deposition showed two wide response ranges, namely, 0.02-1 mM and 1-9 mM, with sensitivities of 3.20 and 1.41 mA mM(-1) cm(-2), respectively, and a detection limit of 1.2 μM (S/N = 3). The sensor also showed good long-term stability as well as high selectivity in the presence of interferences such as ascorbic acid, acetaminophen, and uric acid. This finding reveals the possibility of exploiting the NND as an electrochemical biosensor platform where high performance addressable sensor arrays could be built.

  5. Platinum decorated carbon nanotubes for highly sensitive amperometric glucose sensing

    International Nuclear Information System (INIS)

    Xie Jining; Wang Shouyan; Aryasomayajula, L; Varadan, V K

    2007-01-01

    Fine platinum nanoparticles (1-5 nm in diameter) were deposited on functionalized multi-walled carbon nanotubes (MWNTs) through a decoration technique. A novel type of enzymatic Pt/MWNTs paste-based mediated glucose sensor was fabricated. Electrochemical measurements revealed a significantly improved sensitivity (around 52.7 μA mM -1 cm -2 ) for glucose sensing without using any picoampere booster or Faraday cage. In addition, the calibration curve exhibited a good linearity in the range of 1-28 mM of glucose concentration. Transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) were performed to investigate the nanoscale structure and the chemical bonding information of the Pt/MWNTs paste-based sensing material, respectively. The improved sensitivity of this novel glucose sensor could be ascribed to its higher electroactive surface area, enhanced electron transfer, efficient enzyme immobilization, unique interaction in nanoscale and a synergistic effect on the current signal from possible multi-redox reactions

  6. Computing the net primary productivity for a savannah-dominated ecosystem using stable isotopes: a case study of the Volta River Basin

    International Nuclear Information System (INIS)

    Hayford, E.K.

    2008-01-01

    The hydrologic systems and the terrestrial ecosystem of the Volta river basin in West Africa, play important role in the carbon cycle. This is so because of the coupling of water vapour release and CO 2 uptake during photosynthesis, expressed as water use efficiency or transpiration ratio. Hydrologic and land-cover data, together with stable isotope ratio measurements of δ 18 O and δD, and data from the global network of isotopes in precipitation (GNIP) are used to determine the net primary productivity (NPP) of the Savannah-dominated ecosystem. The δ 18 O and δD values in the Volta rivers range from -4.72 to 2.37 mm -l and from -35.28 to 9.30 mm -1 SMOW, respectively. The results indicate that the vegetation is supported by 380 km 3 of rainfall, out of which 50% is returned to the atmosphere via plant transpiration. Associated with annual transpiration is the NPP of 0.170 x 10 15 gCyr -1 or 428 gCm -2 from the terrestrial ecosystem. Modelled estimates of heterotrophic soil respiration in this study slightly exceeded the NPP estimates, implying a small source of CO 2 to the atmosphere. This condition does not favour the postulated existence of a major sink of atmospheric CO 2 in the Volta basin. (au)

  7. A novel detection platform for parallel monitoring of DNA hybridization with high sensitivity and specificity

    DEFF Research Database (Denmark)

    Yi, Sun; Perch-Nielsen, Ivan R.; Wang, Zhenyu

    We developed a high-sensitive platform to monior multiple hybridization events in real time. By creating a microoptical array in a polymeric chip, the system combine the excellent discriminative power of supercritical angle fluorescence (SAF) microscopy with high-throughput capabilities of microa......We developed a high-sensitive platform to monior multiple hybridization events in real time. By creating a microoptical array in a polymeric chip, the system combine the excellent discriminative power of supercritical angle fluorescence (SAF) microscopy with high-throughput capabilities...

  8. Curcumin inhibits amygdaloid kindled seizures in rats.

    Science.gov (United States)

    DU, Peng; Li, Xin; Lin, Hao-Jie; Peng, Wei-Feng; Liu, Jian-Ying; Ma, Yu; Fan, Wei; Wang, Xin

    2009-06-20

    Curcumin can reduce the severity of seizures induced by kainate acid (KA), but the role of curcumin in amygdaloid kindled models is still unknown. This study aimed to explore the effect of curcumin on the development of kindling in amygdaloid kindled rats. With an amygdaloid kindled Sprague-Dawley (SD) rat model and an electrophysiological method, different doses of curcumin (10 mgxkg(-1)xd(-1) and 30 mgxkg(-1)xd(-1) as low dose groups, 100 mgxkg(-1)xd(-1) and 300 mgxkg(-1)xd(-1) as high dose groups) were administrated intraperitoneally during the whole kindling days, by comparison with the course of kindling, afterdischarge (AD) thresholds and the number of ADs to reach the stages of class I to V seizures in the rats between control and experimental groups. One-way or two-way ANOVA and Fisher's least significant difference post hoc test were used for statistical analyses. Curcumin (both 100 mgxkg(-1)xd(-1) and 300 mgxkg(-1)xd(-1)) significantly inhibited the behavioral seizure development in the (19.80 +/- 2.25) and (21.70 +/- 2.21) stimulations respectively required to reach the kindled state. Rats treated with 100 mgxkg(-1)xd(-1) curcumin 30 minutes before kindling stimulation showed an obvious increase in the stimulation current intensity required to evoke AD from (703.3 +/- 85.9) microA to (960.0 +/- 116.5) microA during the progression to class V seizures. Rats treated with 300 mgxkg(-1)xd(-1) curcumin showed a significant increase in the stimulation current intensity required to evoke AD from (735.0 +/- 65.2) microA to (867.0 +/- 93.4) microA during the progression to class V seizures. Rats treated with 300 mgxkg(-1)xd(-1) curcumin required much more evoked ADs to reach the stage of class both IV (as (199.83 +/- 12.47) seconds) and V seizures (as (210.66 +/- 10.68) seconds). Rats treated with 100 mgxkg(-1)xd(-1) curcumin required much more evoked ADs to reach the stage of class V seizures (as (219.56 +/- 18.24) seconds). Our study suggests that curcumin has

  9. The TRIUMF optically-pumped polarized H- ion source

    International Nuclear Information System (INIS)

    Levy, C.D.P.; Jayamanna, K.; McDonald, M.

    1995-09-01

    The TRIUMF dc optically-pumped polarized H - ion source (OPPIS) produces 200 microA dc H - current at 85% polarization within a normalized emittance (90%) of 0.8 π mm mrad, for operations at the TRIUMF cyclotron. As a result of development of the ECR primary proton source, 1.6 mA dc polarized H - current is produced within a normalized emittance of 2 π mm mrad, suitable for high energy accelerators. The OPPIS has also been developed for use in a parity non-conservation experiment which has very severe limits on permissible helicity-correlated changes in beam current and energy

  10. A Compton polarimeter for CEBAF Hall A

    Energy Technology Data Exchange (ETDEWEB)

    Bardin, G; Cavata, C; Frois, B; Juillard, M; Kerhoas, S; Languillat, J C; Legoff, J M; Mangeot, P; Martino, J; Platchkov, S; Rebourgeard, P; Vernin, P; Veyssiere, C; CEBAF Hall A Collaboration

    1994-09-01

    The physic program at CEBAF Hall A includes several experiments using 4 GeV polarized electron beam: parity violation in electron elastic scattering from proton and {sup 4}He, electric form factor of the proton by recoil polarization, neutron spin structure function at low Q{sup 2}. Some of these experiments will need beam polarization measurement and monitoring with an accuracy close to 4%, for beam currents ranging from 100 nA to 100 microA. A project of a Compton Polarimeter that will meet these requirements is presented. It will comprise four dipoles and a symmetric cavity consisting of two identical mirrors. 1 fig., 10 refs.

  11. Using NCAP to predict RFI effects in linear bipolar integrated circuits

    Science.gov (United States)

    Fang, T.-F.; Whalen, J. J.; Chen, G. K. C.

    1980-11-01

    Applications of the Nonlinear Circuit Analysis Program (NCAP) to calculate RFI effects in electronic circuits containing discrete semiconductor devices have been reported upon previously. The objective of this paper is to demonstrate that the computer program NCAP also can be used to calcuate RFI effects in linear bipolar integrated circuits (IC's). The IC's reported upon are the microA741 operational amplifier (op amp) which is one of the most widely used IC's, and a differential pair which is a basic building block in many linear IC's. The microA741 op amp was used as the active component in a unity-gain buffer amplifier. The differential pair was used in a broad-band cascode amplifier circuit. The computer program NCAP was used to predict how amplitude-modulated RF signals are demodulated in the IC's to cause undesired low-frequency responses. The predicted and measured results for radio frequencies in the 0.050-60-MHz range are in good agreement.

  12. High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

    International Nuclear Information System (INIS)

    J. Denard; A. Saha; G. Lavessiere

    2001-01-01

    CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 (micro)A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 (micro)A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 (micro)A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described

  13. Instrument developments for inverse photoemission

    International Nuclear Information System (INIS)

    Brenac, A.

    1987-02-01

    Experimental developments principally concerning electron sources for inverse photoemission are presented. The specifications of the electron beam are derived from experiment requirements, taking into account the limitations encountered (space charge divergence). For a wave vector resolution of 0.2 A -1 , the maximum current is 25 microA at 20 eV. The design of a gun providing such a beam in the range 5 to 50 eV is presented. Angle-resolved inverse photoemission experiments show angular effects at 30 eV. For an energy of 10 eV, angular effects should be stronger, but the low efficiency of the spectrometer in this range makes the experiments difficult. The total energy resolution of 0.3 eV is the result mainly of electron energy spread, as expected. The electron sources are based on field effect electron emission from a cathode consisting of a large number of microtips. The emission arises from a few atomic cells for each tip. The ultimate theoretical energy spread is 0.1 eV. This value is not attained because of an interface resistance problem. A partial solution of this problem allows measurement of an energy spread of 0.9 eV for a current of 100 microA emitted at 60 eV. These cathodes have a further advantage in that emission can occur at a low temperature [fr

  14. The anticonvulsant action of nafimidone on kindled amygdaloid seizures in rats.

    Science.gov (United States)

    Albertson, T E; Walby, W F

    1988-01-01

    The anticonvulsant effectiveness of nafimidone (1-[2-naphthoylmethyl]imidazole hydrochloride) was evaluated in the kindled amygdaloid seizure model in rats. Nafimidone (3.1-120 mg/kg i.p.) was evaluated at 30 min in previously kindled rats using both threshold (20 microA increments) and supranthreshold (400 microA) paradigms. Nafimidone (25-50 mg/kg) significantly reduced supranthreshold elicited afterdischarge length and seizure severity only at doses with some prestimulation toxicity. The maximum anticonvulsant effectiveness for the 25 mg/kg i.p. dose of nafimidone was seen between 15 and 30 min utilizing a suprathreshold kindling paradigm. Nafimidone did not significantly elevate seizure thresholds at the doses tested; however, nafimidone (3.1-50 mg/kg) reduced the severity and afterdischarge duration of threshold elicited seizures in a non-dose response manner. Drug-induced electroencephalographic spikes were seen in both cortex and amygdala in most kindled rats receiving 100-120 mg/kg i.p. within 30 min of dosing before electrical stimulation. The frequency of spike and wave complexes increased in most of these animals leading to drug-induced spontaneous seizures and death in approximately 25% before electrical stimulation. This study has demonstrated that although nafimidone can modify both threshold and suprathreshold elicited kindled amygdaloid seizures, it lacks significant specificity in this model of epilepsy.

  15. The anticonvulsant action of AHR-11748 on kindled amygdaloid seizures in rats.

    Science.gov (United States)

    Albertson, T E; Walby, W F

    1987-03-01

    The anticonvulsant effectiveness of AHR-11748 (3-[3-(trifluoromethyl)phenoxy]-1-azetidinecarboxamide) was evaluated in the kindled amygdaloid seizure model in rats. Doses of AHR-11748 that did not cause prestimulation toxicity significantly attenuated elicited afterdischarge durations and the severity of the accompanying behavioral convulsive response in previously kindled rats. AHR-11748 (25-100 mg/kg i.p.) was evaluated at 30 min in previously kindled rats using both threshold (20 microA increments) and suprathreshold (400 microA) paradigms. AHR-11748 (50-100.mg/kg) reduced suprathreshold elicited after discharges and seizure severity. Utilizing a suprathreshold kindling paradigm, the maximum anticonvulsant effectiveness for the 100 mg/kg i.p. dose of AHR-11748 was seen at 180 min. AHR-11748 significantly elevated seizure thresholds only at the 100 mg/kg dose. AHR-11748 (25-100 mg/kg) significantly reduced the severity of threshold elicited seizures. When AHR-11748 (50 and 100 mg/kg i.p.) was administered daily during kindling acquisition, the number of daily trials necessary to complete kindling significantly increased. A reduction in both the duration and the severity of the responses induced by the daily stimulations during the acquisition period was seen with AHR-11748 treatment. This study has demonstrated that AHR-11748 significantly modifies both the acquisition of kindling and the fully kindled amygdaloid seizures at doses that do not cause behavioral toxicity.

  16. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs.

    Science.gov (United States)

    Rodrigues, Anna; Sawkey, Daren; Yin, Fang-Fang; Wu, Qiuwen

    2015-05-01

    To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented. In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm(2) were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R100, R50, Rp, and Rp+ for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R100, R50, and Rp were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement. We have presented a Monte Carlo simulation framework for electron beam dose calculations for Varian TrueBeam Linacs. Electron beam energies of 6 to 20 MeV for open and collimated

  17. Layer by layer assembly of glucose oxidase and thiourea onto glassy carbon electrode: Fabrication of glucose biosensor

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Noorbakhsh, Abdollah

    2011-01-01

    Highlights: → Although various enzymes immobilization have been approve for the construction of glucose biosensor, a layer by layer (LBL) technique has attracted more attention due to simplicity of the procedure, wide choice of materials that can be used, controllability of film thickness and unique mechanical properties. → In this paper, we described a novel and simple strategy for developing an amperometric glucose biosensor based on layer-by-layer self assembly of glucose oxidase on the glassy carbon electrode modified by thiourea. → Thiourea has two amino groups that the one can be immobilized on the activated glassy carbon electrode and the other can be used for the coupling of glucose oxidase enzyme. → The biosensor exhibited good performance for electrocatalytic oxidation of glucose, such as high sensitivity, low detection limit, short response time and wide concentration range. → Finally, the new method is strongly recommended for immobilization of many other enzymes or proteins containing carbaldehyde or carboxylic groups for fabricating third generation biosensors and bioelectronics devices. - Abstract: For the first time a novel, simple and facile approach is described to construct highly stable glucose oxidase (GOx) multilayer onto glassy carbon (GC) electrode using thiourea (TU) as a covalent attachment cross-linker. The layer by layer (LBL) attachment process was confirmed by cyclic voltammetry, electrochemical impedance spectroscopy and Fourier transform infrared reflection spectroscopy (FT-IR-RS) techniques. Immobilized GOx shows excellent electrocatalytic activity toward glucose oxidation using ferrocenemethanol as artificial electron transfer mediator and biosensor response was directly correlated to the number of bilayers. The surface coverage of active GOx per bilayer, heterogeneous electron transfer rate constant (k s ) and Michaelis-Menten constant (K M ), of immobilized GOx were 1.50 x 10 -12 mol cm -2 , 9.2 ± 0.5 s -1 and 3.42(±0

  18. An amperometric H2O2 biosensor based on hemoglobin nanoparticles immobilized on to a gold electrode.

    Science.gov (United States)

    Narwal, Vinay; Yadav, Neelam; Thakur, Manisha; Pundir, Chandra S

    2017-08-31

    The nanoparticles (NPs) of hemoglobin (Hb) were prepared by desolvation method and characterized by transmission electron microscopy (TEM), UV spectroscopy and Fourier-transform IR (FTIR) spectroscopy. An amperometric H 2 O 2 biosensor was constructed by immobilizing HbNPs covalently on to a polycrystalline Au electrode (AuE). HbNPs/AuE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) before and after immobilization of HbNPs. The HbNPs/AuE showed optimum response within 2.5 s at pH 6.5 in 0.1 M sodium phosphate buffer (PB) containing 100 μM H 2 O 2 at 30°C, when operated at -0.2 V against Ag/AgCl. The HbNPs/AuE exhibited V max of 5.161 ± 0.1 μA cm -2 with apparent Michaelis-Menten constant ( K m ) of 0.1 ± 0.01 mM. The biosensor showed lower detection limit (1.0 μM), high sensitivity (129 ± 0.25 μA cm -2 mM -1 ) and wider linear range (1.0-1200 μM) for H 2 O 2 as compared with earlier biosensors. The analytical recoveries of added H 2 O 2 in serum (0.5 and 1.0 μM) were 97.77 and 98.01% respectively, within and between batch coefficients of variation (CV) were 3.16 and 3.36% respectively. There was a good correlation between sera H 2 O 2 values obtained by standard enzymic colorimetric method and the present biosensor (correlation coefficient, R 2 =0.99). The biosensor measured H 2 O 2 level in sera of apparently healthy subjects and persons suffering from diabetes type II. The HbNPs/AuE lost 10% of its initial activity after 90 days of regular use, when stored dry at 4°C. © 2017 The Author(s).

  19. Accurate convolution/superposition for multi-resolution dose calculation using cumulative tabulated kernels

    International Nuclear Information System (INIS)

    Lu Weiguo; Olivera, Gustavo H; Chen Mingli; Reckwerdt, Paul J; Mackie, Thomas R

    2005-01-01

    Convolution/superposition (C/S) is regarded as the standard dose calculation method in most modern radiotherapy treatment planning systems. Different implementations of C/S could result in significantly different dose distributions. This paper addresses two major implementation issues associated with collapsed cone C/S: one is how to utilize the tabulated kernels instead of analytical parametrizations and the other is how to deal with voxel size effects. Three methods that utilize the tabulated kernels are presented in this paper. These methods differ in the effective kernels used: the differential kernel (DK), the cumulative kernel (CK) or the cumulative-cumulative kernel (CCK). They result in slightly different computation times but significantly different voxel size effects. Both simulated and real multi-resolution dose calculations are presented. For simulation tests, we use arbitrary kernels and various voxel sizes with a homogeneous phantom, and assume forward energy transportation only. Simulations with voxel size up to 1 cm show that the CCK algorithm has errors within 0.1% of the maximum gold standard dose. Real dose calculations use a heterogeneous slab phantom, both the 'broad' (5 x 5 cm 2 ) and the 'narrow' (1.2 x 1.2 cm 2 ) tomotherapy beams. Various voxel sizes (0.5 mm, 1 mm, 2 mm, 4 mm and 8 mm) are used for dose calculations. The results show that all three algorithms have negligible difference (0.1%) for the dose calculation in the fine resolution (0.5 mm voxels). But differences become significant when the voxel size increases. As for the DK or CK algorithm in the broad (narrow) beam dose calculation, the dose differences between the 0.5 mm voxels and the voxels up to 8 mm (4 mm) are around 10% (7%) of the maximum dose. As for the broad (narrow) beam dose calculation using the CCK algorithm, the dose differences between the 0.5 mm voxels and the voxels up to 8 mm (4 mm) are around 1% of the maximum dose. Among all three methods, the CCK algorithm

  20. A comparative study of graphene-hydrogel hybrid bionanocomposites for biosensing.

    Science.gov (United States)

    Burrs, S L; Vanegas, D C; Rong, Y; Bhargava, M; Mechulan, N; Hendershot, P; Yamaguchi, H; Gomes, C; McLamore, E S

    2015-03-07

    Hydrogels have become increasingly popular as immobilization materials for cells, enzymes and proteins for biosensing applications. Enzymatic biosensors that utilize hydrogel as an encapsulant have shown improvements over other immobilization techniques such as cross linking and covalent bonding. However, to date there are no studies which directly compare multiple hydrogel-graphene nanocomposites using the same enzyme and test conditions. This study compares the performance of four different hydrogels used as protein encapsulants in a mediator-free biosensor based on graphene-nanometal-enzyme composites. Alcohol oxidase (AOx) was encapsulated in chitosan poly-N-isopropylacrylamide (PNIPAAM), silk fibroin or cellulose nanocrystals (CNC) hydrogels, and then spin coated onto a nanoplatinum-graphene modified electrode. The transduction mechanism for the biosensor was based on AOx-catalyzed oxidation of methanol to produce hydrogen peroxide. To isolate the effect(s) of stimulus response on biosensor behavior, all experiments were conducted at 25 °C and pH 7.10. Electroactive surface area (ESA), electrochemical impedance spectroscopy (EIS), sensitivity to methanol, response time, limit of detection, and shelf life were measured for each bionanocomposite. Chitosan and PNIPAAM had the highest sensitivity (0.46 ± 0.2 and 0.3 ± 0.1 μA mM(-1), respectively) and electroactive surface area (0.2 ± 0.06 and 0.2 ± 0.02 cm(2), respectively), as well as the fastest response time (4.3 ± 0.8 and 4.8 ± 1.1 s, respectively). Silk and CNC demonstrated lower sensitivity (0.09 ± 0.02 and 0.15 ± 0.03 μA mM(-1), respectively), lower electroactive surface area (0.12 ± 0.02 and 0.09 ± 0.03 cm(2), respectively), and longer response time (8.9 ± 2.1 and 6.3 ± 0.8 s, respectively). The high porosity of chitosan, PNIPAAM, and silk gels led to excellent transport, which was significantly better than CNC bionanocomposites. Electrochemical performance of CNC bionanocomposites were

  1. Morphometric variability of precuneus in relation to gender and the hemisphere of human brain

    Directory of Open Access Journals (Sweden)

    Spasojević Goran

    2004-01-01

    Full Text Available Precuneus, a quadrangular gyrus of the medial surface of the human parietal lobe, is bound by three primary brain sulci and by superior hemispheric border. Precise encephalometric data about precuneus are important in the studies of brain lateralization, sex dimorphism, and brain functions in general. In this study, total and visible (exstrasulcal surface area of the precuneus were measured on 50 brains of the adult persons (31 male, and 29 female, together with the investigation of its relationship to the side (left/right and gender (sex dimorphism. The average total surface area of the precuneus was 16.07 cm2 on the right (males 16.44 cm2, females 15.27 cm2, and 15.44 cm2 on the left (males 15.67 cm2, females 14.62 cm2. The average visible (extrasulcal surface area of cortex of precuneus was 9.97 cm2 on the left (males 10.75 cm2, females 8.91 cm2, and 9.38 cm2 on the right (males 10.25 cm2, females 8.19 cm2. Exstrasulcal surface area of the left precuneus was larger, by 0.59 cm on the average, which was not statistically significant. Total surface area of precuneus of males was significantly larger on the right (16.44 cm2 (p<0.01 than on the left (15.67 cm2. In females it was also larger on the right (15.27 cm2 than on the left (14.62 cm2, but with no statistical significance. Visible (exstrasulcal surface area of both, (left and right precuneus of males was highly significantly larger in comparison with the females (p<0.001. The obtained results and other facts suggested that sex dimorphism of human brain, including precuneus, was present, but not always easily observable studied or proven in all the details.

  2. Objective Crystal Spectrometer on the SRG satellite

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Westergaard, Niels Jørgen Stenfeldt; Rasmussen, I.

    1994-01-01

    . They confirm our specifications for the overall performance of the OXS. An estimate of the effective area in the 4 energy windows that are available to OXS yields > 100 cm2 from 5 to 7.4 keV, > 200 cm2 from 2.3 to 4.6 keV, approximately 10 cm+2) from 0.55 to 0.81 keV and approximately 100 cm2 from 0.175 to 0...

  3. Ablation from metals induced by visible and UV laser irradiation

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Schou, Jørgen; Thestrup Nielsen, Birgitte

    1996-01-01

    The deposition rate of laser-ablated silver has been determined for fluences between 0.5 and 15 J/cm2 at the wavelengths 532 and 355 nm for a beam spot area of around 0.01 cm2. The ablated metal was collected on a quartz crystal microbalance. The rate at 5 J/cm2 was about 4 × 1013 Ag/cm2 per pulse...

  4. High performance and highly durable infiltrated cathodes using Pr-modified Ce0.9Gd0.1O1.95 backbone

    DEFF Research Database (Denmark)

    Samson, Alfred Junio; Søgaard, Martin; Bonanos, Nikolaos

    2014-01-01

    °C (without Pr: Rp from 0.094 to 0.45 Ω cm2, Rs from 0.74 to 0.79 Ω cm2; with Pr: Rp from 0.051 to 0.32 Ω cm2, Rs from 0.74 to 0.71 Ω cm2). The improved performance and heat treatment tolerance is thought to originate from the imparted electronic conductivity into the CGO backbone by introducing Pr....

  5. Flow-injection amperometric determination of glucose using a biosensor based on immobilization of glucose oxidase onto Au seeds decorated on core Fe₃O₄ nanoparticles.

    Science.gov (United States)

    Samphao, Anchalee; Butmee, Preeyanut; Jitcharoen, Juthamas; Švorc, Ľubomír; Raber, Georg; Kalcher, Kurt

    2015-09-01

    An amperometric biosensor based on chemisorption of glucose oxidase (GOx) on Au seeds decorated on magnetic core Fe3O4 nanoparticles (Fe3O4@Au) and their immobilization on screen-printed carbon electrode bulk-modified with manganese oxide (SPCE{MnO2}) was designed for the determination of glucose. The Fe3O4@Au/GOx modified SPCE{MnO2} was used in a flow-injection analysis (FIA) arrangement. The experimental conditions were investigated in amperometric mode with the following optimized parameters: flow rate 1.7 mL min(-1), applied potential +0.38 V, phosphate buffer solution (PBS; 0.1 mol L(-1), pH 7.0) as carrier and 3.89 unit mm(-2) enzyme glucose oxidase loading on the active surface of the SPCE. The designed biosensor in FIA arrangement yielded a linear dynamic range for glucose from 0.2 to 9.0 mmol L(-1) with a sensitivity of 2.52 µA mM(-1) cm(-2), a detection limit of 0.1 mmol L(-1) and a quantification limit of 0.3 mmol L(-1). Moreover, a good repeatability of 2.8% (number of measurements n=10) and a sufficient reproducibility of 4.0% (number of sensors n=3) were achieved. It was found that the studied system Fe3O4@Au facilitated not only a simpler enzyme immobilization but also provided wider linear range. The practical application of the proposed biosensor for FIA quantification of glucose was tested in glucose sirup samples, honeys and energy drinks with the results in good accordance with those obtained by an optical glucose meter and with the contents declared by the producers. Copyright © 2015. Published by Elsevier B.V.

  6. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    Science.gov (United States)

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. © 2013 Elsevier Ltd. All rights reserved.

  7. Hollow TiO2 modified reduced graphene oxide microspheres encapsulating hemoglobin for a mediator-free biosensor.

    Science.gov (United States)

    Liu, Hui; Guo, Kai; Duan, Congyue; Dong, Xiaonan; Gao, Jiaojiao

    2017-01-15

    Hollow TiO 2 modified reduced graphene oxide microspheres (hollow TiO 2 -rGO microspheres or H-TiO 2 -rGO MS) have been synthesized and then be used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of hollow TiO 2 -rGO microspheres were characterized by scanning electron microscopy, transmission electronic microscopy and X-ray diffraction. Results of spectroscopy and electrochemistry tests revealed that hollow TiO 2 -rGO microsphere is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. The hollow TiO 2 -rGO microspheres with special structure and component enhance the immobilization efficiency of proteins and facilitate the direct electron transfer, which result in the better H 2 O 2 detection performance-the wide linear range of 0.1-360μM for H 2 O 2 (sensitivity of 417.6 μA mM -1 cm -2 ) and the extremely low detection limit of 10nM for H 2 O 2 . Moreover, the hollow microsphere can provide a protective microenvironment for Hb to make the as-prepared biosensor improve long-term stability. The as-prepared biosensor retains 95.4% of the initial response to H 2 O 2 after 60-d storage. Hence, this work suggests that if can be fabricated a mediator-free biosensor, hollow TiO 2 -rGO microspheres will find wide potential applications in environmental analysis and biomedical detection. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Growth of coral-like PtAu-MnO2 binary nanocomposites on free-standing graphene paper for flexible nonenzymatic glucose sensors.

    Science.gov (United States)

    Xiao, Fei; Li, Yuanqing; Gao, Hongcai; Ge, Shuibing; Duan, Hongwei

    2013-03-15

    The growing demand for compact point-of-care medical devices and portable instruments for on-site environmental sampling has stimulated intense research on flexible sensors that can be miniaturized and function under considerable physical deformation. We report a new type of flexible electrochemical biosensors based on free-standing graphene paper carrying binary nanocomposites of PtAu alloy and MnO(2). The coral-like PtAu-MnO(2) nanocomposites are grown on the substrate through one-step template-free electrodeposition, leading to an intimate contact between the PtAu alloy and MnO(2) matrix. The flexible electrode exhibits a unique set of structural and electrochemical properties such as better uniformity, larger active surface areas, and faster electron transfer in comparison with the control electrode prepared by tandem growth of MnO(2) network and PtAu alloy in two steps. In nonenzymatic amperometric glucose detection, the PtAu-MnO(2) binary nanostructure-decorated graphene paper has shown greatly enhanced sensing performance such as wide liner range (0.1 mM to 30.0 mM), high sensitivity (58.54 μA cm(-2) mM(-1)), low detection limit (0.02 mM, S/N=3), satisfactory selectivity, excellent reproducibility and stability, and tolerability to mechanical stress. The strategy of co-growth of metal and metal oxides on freestanding carbon substrates opens new possibility to develop high-performance flexible electrochemical sensors. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Development of a Sensitive Electrochemical Enzymatic Reaction-Based Cholesterol Biosensor Using Nano-Sized Carbon Interdigitated Electrodes Decorated with Gold Nanoparticles.

    Science.gov (United States)

    Sharma, Deepti; Lee, Jongmin; Seo, Junyoung; Shin, Heungjoo

    2017-09-15

    We developed a versatile and highly sensitive biosensor platform. The platform is based on electrochemical-enzymatic redox cycling induced by selective enzyme immobilization on nano-sized carbon interdigitated electrodes (IDEs) decorated with gold nanoparticles (AuNPs). Without resorting to sophisticated nanofabrication technologies, we used batch wafer-level carbon microelectromechanical systems (C-MEMS) processes to fabricate 3D carbon IDEs reproducibly, simply, and cost effectively. In addition, AuNPs were selectively electrodeposited on specific carbon nanoelectrodes; the high surface-to-volume ratio and fast electron transfer ability of AuNPs enhanced the electrochemical signal across these carbon IDEs. Gold nanoparticle characteristics such as size and morphology were reproducibly controlled by modulating the step-potential and time period in the electrodeposition processes. To detect cholesterol selectively using AuNP/carbon IDEs, cholesterol oxidase (ChOx) was selectively immobilized via the electrochemical reduction of the diazonium cation. The sensitivity of the AuNP/carbon IDE-based biosensor was ensured by efficient amplification of the redox mediators, ferricyanide and ferrocyanide, between selectively immobilized enzyme sites and both of the combs of AuNP/carbon IDEs. The presented AuNP/carbon IDE-based cholesterol biosensor exhibited a wide sensing range (0.005-10 mM) and high sensitivity (~993.91 µA mM -1 cm -2 ; limit of detection (LOD) ~1.28 µM). In addition, the proposed cholesterol biosensor was found to be highly selective for the cholesterol detection.

  10. Dual functional rhodium oxide nanocorals enabled sensor for both non-enzymatic glucose and solid-state pH sensing.

    Science.gov (United States)

    Dong, Qiuchen; Huang, Yikun; Song, Donghui; Wu, Huixiang; Cao, Fei; Lei, Yu

    2018-07-30

    Both pH-sensitive and glucose-responsive rhodium oxide nanocorals (Rh 2 O 3 NCs) were synthesized through electrospinning followed by high-temperature calcination. The as-prepared Rh 2 O 3 NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy, and then employed as a dual functional nanomaterial to fabricate a dual sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. The sensing performance of the Rh 2 O 3 NCs based dual sensor toward pH and glucose was evaluated using open circuit potential, cyclic voltammetry and amperometric techniques, respectively. The results show that the as-prepared Rh 2 O 3 NCs not only maintain accurate and reversible pH sensitivity of Rh 2 O 3 , but also demonstrate a good electrocatalytic activity toward glucose oxidation in alkaline medium with a sensitivity of 11.46 μA mM -1 cm -2 , a limit of detection of 3.1 μM (S/N = 3), and a reasonable selectivity against various interferents in non-enzymatic glucose detection. Its accuracy in determining glucose in human serum samples was further demonstrated. These features indicate that the as-prepared Rh 2 O 3 NCs hold great promise as a dual-functional sensing material in the development of a high-performance sensor forManjakkal both solid-state pH and non-enzymatic glucose sensing. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Glucose biosensor based on a glassy carbon electrode modified with polythionine and multiwalled carbon nanotubes.

    Directory of Open Access Journals (Sweden)

    Wenwei Tang

    Full Text Available A novel glucose biosensor was fabricated. The first layer of the biosensor was polythionine, which was formed by the electrochemical polymerisation of the thionine monomer on a glassy carbon electrode. The remaining layers were coated with chitosan-MWCNTs, GOx, and the chitosan-PTFE film in sequence. The MWCNTs embedded in FAD were like "conductive wires" connecting FAD with electrode, reduced the distance between them and were propitious to fast direct electron transfer. Combining with good electrical conductivity of PTH and MWCNTs, the current response was enlarged. The sensor was a parallel multi-component reaction system (PMRS and excellent electrocatalytic performance for glucose could be obtained without a mediator. The glucose sensor had a working voltage of -0.42 V, an optimum working temperature of 25°C, an optimum working pH of 7.0, and the best percentage of polytetrafluoroethylene emulsion (PTFE in the outer composite film was 2%. Under the optimised conditions, the biosensor displayed a high sensitivity of 2.80 µA mM(-1 cm(-2 and a low detection limit of 5 µM (S/N = 3, with a response time of less than 15 s and a linear range of 0.04 mM to 2.5 mM. Furthermore, the fabricated biosensor had a good selectivity, reproducibility, and long-term stability, indicating that the novel CTS+PTFE/GOx/MWCNTs/PTH composite is a promising material for immobilization of biomolecules and fabrication of third generation biosensors.

  12. Tungsten oxide-Au nanosized film composites for glucose oxidation and sensing in neutral medium

    Directory of Open Access Journals (Sweden)

    Gougis M

    2015-04-01

    Full Text Available Maxime Gougis, Dongling Ma, Mohamed Mohamedi INRS-Énergie, Matériaux et Télécommunications, Varennes, Québec, Canada Abstract: In this work, we report for the first time the use of tungsten oxide (WOx as catalyst support for Au toward the direct electrooxidation of glucose. The nanostructured WOx/Au electrodes were synthesized by means of laser-ablation technique. Both micro-Raman spectroscopy and transmission electron microscopy showed that the produced WOx thin film is amorphous and made of ultrafine particles of subnanometer size. X-ray diffraction and X-ray photoelectron spectroscopy revealed that only metallic Au was present at the surface of the WOx/Au composite, suggesting that the WOx support did not alter the electronic structure of Au. The direct electrocatalytic oxidation of glucose in neutral medium such as phosphate buffered saline (pH 7.2 solution has been investigated with cyclic voltammetry, chronoamperometry, and square-wave voltammetry. Sensitivity as high as 65.7 µA cm-2 mM-1 up to 10 mM of glucose and a low detection limit of 10 µM were obtained with square-wave voltammetry. This interesting analytical performance makes the laser-fabricated WOx/Au electrode potentially promising for implantable glucose fuel cells and biomedical analysis as the evaluation of glucose concentration in biological fluids. Finally, owing to its unique capabilities proven in this work, it is anticipated that the laser-ablation technique will develop as a fabrication tool for chip miniature-sized sensors in the near future. Keywords: Au, tungsten oxide, nanostructures, pulsed laser deposition, glucose oxidation and sensing

  13. Characterization of different FAD-dependent glucose dehydrogenases for possible use in glucose-based biosensors and biofuel cells.

    Science.gov (United States)

    Zafar, Muhammad Nadeem; Beden, Najat; Leech, Dónal; Sygmund, Christoph; Ludwig, Roland; Gorton, Lo

    2012-02-01

    In this study, different flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenases (FADGDHs) were characterized electrochemically after "wiring" them with an osmium redox polymer [Os(4,4'-dimethyl-2,2'-bipyridine)(2)(PVI)(10)Cl](+) on graphite electrodes. One tested FADGDH was that recently discovered in Glomerella cingulata (GcGDH), another was the recombinant form expressed in Pichia pastoris (rGcGDH), and the third was a commercially available glycosylated enzyme from Aspergillus sp. (AspGDH). The performance of the Os-polymer "wired" GDHs on graphite electrodes was tested with glucose as the substrate. Optimal operational conditions and analytical characteristics like sensitivity, linear ranges and current density of the different FADGDHs were determined. The performance of all three types of FADGDHs was studied at physiological conditions (pH 7.4). The current densities measured at a 20 mM glucose concentration were 494 ± 17, 370 ± 24, and 389 ± 19 μA cm(-2) for GcGDH, rGcGDH, and AspGDH, respectively. The sensitivities towards glucose were 2.16, 1.90, and 1.42 μA mM(-1) for GcGDH, rGcGDH, and AspGDH, respectively. Additionally, deglycosylated rGcGDH (dgrGcGDH) was investigated to see whether the reduced glycosylation would have an effect, e.g., a higher current density, which was indeed found. GcGDH/Os-polymer modified electrodes were also used and investigated for their selectivity for a number of different sugars.

  14. Copper@carbon coaxial nanowires synthesized by hydrothermal carbonization process from electroplating wastewater and their use as an enzyme-free glucose sensor.

    Science.gov (United States)

    Zhao, Yuxin; He, Zhaoyang; Yan, Zifeng

    2013-01-21

    In the pursuit of electrocatalysts with great economic and ecological values for non-enzymatic glucose sensors, one-dimensional copper@carbon (Cu@C) core-shell coaxial nanowires (NWs) have been successfully prepared via a simple continuous flow wet-chemistry approach from electroplating wastewater. The as-obtained products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. The electrocatalytic activity of the modified electrodes by Cu@C NWs towards glucose oxidation was investigated by cyclic voltammetry and chronoamperometry. It was found that the as-obtained Cu@C NWs showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Compared to the other electrodes including the bare Nafion/glassy carbon electrode (GCE) and several hot hybrid nanostructures modified GCE, a substantial decrease in the overvoltage of the glucose oxidation was observed at the Cu@C NWs electrodes with oxidation starting at ca. 0.20 V vs. Ag/AgCl (3 M KCl). At an applied potential of 0.65 V, Cu@C NWs electrodes had a high and reproducible sensitivity of 437.8 µA cm(-2) mM(-1) to glucose. Linear responses were obtained with a detection limit of 50 nM. More importantly, the proposed electrode also had good stability, high resistance against poisoning by chloride ion and commonly interfering species. These good analytical performances make Cu@C NWs promising for the future development of enzyme-free glucose sensors.

  15. Effect of Carcass Traits on Carcass Prices of Holstein Steers in Korea

    Science.gov (United States)

    Alam, M.; Cho, K. H.; Lee, S. S.; Choy, Y. H.; Kim, H. S.; Cho, C. I.; Choi, T. J.

    2013-01-01

    The present study investigated the contribution of carcass traits on carcass prices of Holstein steers in Korea. Phenotypic data consisted of 76,814 slaughtered Holsteins (1 to 6 yrs) from all over Korea. The means for live body weight at slaughter (BWT), chilled carcass weight (CWT), dressing percentage (DP), quantity grade index (QGI), eye muscle area (EMA), backfat thickness (BF) and marbling score (MS), carcass unit price (CUP), and carcass sell prices (CSP) were 729.0 kg, 414.2 kg, 56.79%, 64.42, 75.26 cm2, 5.77 mm, 1.98, 8,952.80 Korean won/kg and 3,722.80 Thousand Korean won/head. Least squares means were significantly different by various age groups, season of slaughter, marbling scores and yield grades. Pearson’s correlation coefficients of CUP with carcass traits ranged from 0.12 to 0.62. Besides, the relationships of carcass traits with CSP were relatively stronger than those with CUP. The multiple regression models for CUP and CSP with carcass traits accounted 39 to 63% of the total variation, respectively. Marbling score had maximum economic effects (partial coefficients) on both prices. In addition, the highest standardized partial coefficients (relative economic weights) for CUP and CSP were calculated to be on MS and CWT by 0.608 and 0.520, respectively. Path analyses showed that MS (0.376) and CWT (0.336) had maximum total effects on CUP and CSP, respectively; whereas BF contributed negatively. Further sub-group (age and season of slaughter) analyses also confirmed the overall outcomes. However, the relative economic weights and total path contributions also varied among the animal sub-groups. This study suggested the significant influences of carcass traits on carcass prices; especially MS and CWT were found to govern the carcass prices of Holstein steers in Korea. PMID:25049722

  16. A novel amperometric alcohol biosensor developed in a 3rd generation bioelectrode platform using peroxidase coupled ferrocene activated alcohol oxidase as biorecognition system.

    Science.gov (United States)

    Chinnadayyala, Somasekhar R; Kakoti, Ankana; Santhosh, Mallesh; Goswami, Pranab

    2014-05-15

    Alcohol oxidase (AOx) with a two-fold increase in efficiency (Kcat/Km) was achieved by physical entrapment of the activator ferrocene in the protein matrix through a simple microwave based partial unfolding technique and was used to develop a 3rd generation biosensor for improved detection of alcohol in liquid samples. The ferrocene molecules were stably entrapped in the AOx protein matrix in a molar ratio of ~3:1 through electrostatic interaction with the Trp residues involved in the functional activity of the enzyme as demonstrated by advanced analytical techniques. The sensor was fabricated by immobilizing ferrocene entrapped alcohol oxidase (FcAOx) and sol-gel chitosan film coated horseradish peroxidase (HRP) on a multi-walled carbon nanotube (MWCNT) modified glassy carbon electrode through layer-by-layer technique. The bioelectrode reactions involved the formation of H2O2 by FcAOx biocatalysis of substrate alcohol followed by HRP-catalyzed reduction of the liberated H2O2 through MWCNT supported direct electron transfer mechanism. The amperometric biosensor exhibited a linear response to alcohol in the range of 5.0 × 10(-6) to 30 × 10(-4)mol L(-1) with a detection limit of 2.3 × 10(-6) mol L(-1), and a sensitivity of 150 µA mM(-1) cm(-2). The biosensor response was steady for 28 successive measurements completed in a period of 5h and retained ~90% of the original response even after four weeks when stored at 4 °C. The biosensor was successfully applied for the determination of alcohol in commercial samples and its performance was validated by comparing with the data obtained by GC analyses of the samples. © 2013 Published by Elsevier B.V.

  17. Beta dosimetry in intraperitoneal administration of 166Ho-chitosan complex

    International Nuclear Information System (INIS)

    Kim, E. H.; Lim, S. M.; Park, K. B.

    1998-01-01

    Intraperitoneal administration of radioisotopes is suggested to treat the metastatic ovarian cancer in the peritoneal cavity. Administering beta-emitting radioisotopes into the peritoneal cavity allows the maximum energy delivery to the cancerous cells of the peritoneal wall surface while sparing the normal cells located in deep site of the peritoneal wall. In this study, dose estimates of the peritoneal wall are provided to be used for prescribing the amount of 166 Ho-chitosan complex administered. The 166 Ho-chitosan complex diffused in the peritoneal fluid may attach to the peritoneal wall surface. The attachment fraction of 166 Ho-chitosan complex to the peritoneal wall surface is obtained by simulating the ascites with Fischer rats. Both volume source in the peritoneal fluid and the surface source over the peritoneal wall surface are counted for the contribution to the peritoneal wall dose. The Monte Carlo code EGS4 is used to simulate the energy transfer of the beta particles emitted from 166 Ho. A plane geometrical model of semi-infinite volume describes the peritoneal cavity and the peritoneal wall. A semi-infinite plane of 10 μm in thickness at every 1 mm of depth in the peritoneal wall is taken as the target in dose estimation. Greater than 98 percents of attachment fraction has been observed from the experiments with Fischer rats. Given 1.3 μCi/cm 2 and 2.4 μCi/ml of uniform activity density, absorbed dose is 123 Gy, 8.59 Gy, 3.00 Gy, 1.03 Gy, and 327 Gy at 0 mm, 1 mm, 2 mm, 3 mm, and 4 mm in depth to the peritoneal wall, respectively

  18. Irradiation effects on fracture toughness of two high-copper submerged-arc welds, HSSI series 5

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Haggag, F.M.; McCabe, D.E.; Iskander, S.K.; Bowman, K.O.; Menke, B.H.

    1992-10-01

    The Fifth Irradiation Series in the Heavy-Section Steel irradiation (HSSI) Program was aimed at obtaining a statistically significant fracture toughness data base on two weldments with high-copper contents to determine the shift and shape of the K lc curve as a consequence of irradiation. The program included irradiated Charpy V-notch impact, tensile, and drop-weight specimens in addition to compact fracture toughness specimens. Compact specimens with thicknesses of 25.4, 50.8, and 101.6 mm [1T C(T), 2T C(T), and 4T C(T), respectively] were irradiated. Additionally, unirradiated 6T C(T) and 8T C(T) specimens with the same K lc measuring capacity as the irradiated specimens were tested. The materials for this irradiation series were two weldments fabricated from special heats of weld wire with copper added to the melt. One lot of Linde 0124 flux was used for all the welds. Copper levels for the two welds are 0.23 and 0.31 wt %, while the nickel contents for both welds are 0.60 wt %. Twelve capsules of specimens were irradiated in the pool-side facility of the Oak Ridge Research Reactor at a nominal temperature of 288 degree C and an average fluence of about 1.5 x 10 19 neutrons/cm 2 (> 1 MeV). This volume, Appendices E and F, contains the load-displacement curves and photographs of the fracture toughness specimens from the 72W weld (0.23 wt % Cu) and the 73 W weld (0.31 wt % Cu), respectively

  19. Disposable L-lactate biosensor based on a screen-printed carbon electrode enhanced by graphene

    Science.gov (United States)

    Tu, Dandan; He, Yu; Rong, Yuanzhen; Wang, You; Li, Guang

    2016-04-01

    In this work, an amperometric L-lactate biosensor based on a graphene-modified screen-printed carbon electrode (SPCE) was constructed. First, the electrocatalytic performance of the SPCE modified with graphene by a one-step electrodeposition process (OerGO/SPCE) was investigated. The cyclic voltammogram of OerGO/SPCE, which showed a well-defined redox peak, had a smaller peak potential separation than that of SPCE, revealing the improvement in electron transfer speed brought about by modifying with graphene. Next, lactate oxidase and potassium ferricyanide were dropped on the OerGO/SPCE to construct a graphene-modified L-lactate biosensor (LOD/K3[Fe(CN)6]/OerGO/SPCE). The proposed biosensor, with a detection limit of 60 μM, had a high sensitivity (42.42 μA mM-1 cm-2) when working at a low working potential (0.15 V). The linear range was 0.5 mM-15 mM, covering the detecting range of L-lactate in clinical applications. The L-lactate biosensor had a short response time (10 s) and required only 10 μl of the sample. This L-lactate sensor modified with electrodeposited graphene had a larger sensitivity than that based on the bare SPCE. Thus, our low-cost and disposable L-lactate biosensor enhanced by graphene can perform as an attractive electrochemical device that can be manufactured for point-of-care testing (POCT) devices and be employed in POCT applications.

  20. Nonenzymatic free-cholesterol detection via a modified highly sensitive macroporous gold electrode with platinum nanoparticles.

    Science.gov (United States)

    Lee, Yi-Jae; Park, Jae-Yeong

    2010-12-15

    A sensitive macroporous Au electrode with a highly rough surface obtained through the use of with Pt nanoparticles (macroporous Au-/nPts) is reported. It has been designed for nonenzymatic free-cholesterol biosensor applications. A macroporous Au-/nPts electrode was fabricated by electroplating Pt nanoparticles onto a coral-like shaped macroporous Au electrode structure. The macroporous Au-/nPts electrode was physically characterized by field emission scanning electron microscopy (FESEM). It was confirmed that the Pt nanoparticles were well deposited on the surface of the macroporous Au electrode. The porosity and window pore size of the macroporous Au electrode were 50% and 100-300 nm, respectively. The electroplated Pt nanoparticle size was approximately 10-20 nm. Electrochemical experiments showed that the macroporous Au-/nPts exhibited a much larger surface activation area (roughness factor (RF)=2024.7) than the macroporous Au electrode (RF=46.07). The macroporous Au-/nPts also presented a much stronger electrocatalytic activity towards cholesterol oxidation than does the macroporous Au electrode. At 0.2 V, the electrode responded linearly up to a 5 mM cholesterol concentration in a neutral media, with a detection limit of 0.015 mM and detection sensitivity of 226.2 μA mM(-1) cm(-2). Meanwhile, interfering species such as ascorbic acid (AA), acetaminophen (AP), and uric acid (UA), were effectively avoided. This novel nonenzymatic detection electrode has strong applications as an electrochemically based cholesterol biosensor. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. An amperometric bienzymatic cholesterol biosensor based on functionalized graphene modified electrode and its electrocatalytic activity towards total cholesterol determination.

    Science.gov (United States)

    Manjunatha, Revanasiddappa; Shivappa Suresh, Gurukar; Melo, Jose Savio; D'Souza, Stanislaus F; Venkatesha, Thimmappa Venkatarangaiah

    2012-09-15

    Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) have been covalently immobilized onto functionalized graphene (FG) modified graphite electrode. Enzymes modified electrodes were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). FG accelerates the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx. A well defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH(2) of ChOx. The electron transfer coefficient (α) and electron transfer rate constant (K(s)) were calculated and their values are found to be 0.31 and 0.78 s(-1), respectively. For the free cholesterol determination, ChOx-FG/Gr electrode exhibits a sensitive response from 50 to 350 μM (R=-0.9972) with a detection limit of 5 μM. For total cholesterol determination, co-immobilization of ChEt and ChOx on modified electrode, i.e. (ChEt/ChOx)-FG/Gr electrode showed linear range from 50 to 300 μM (R=-0.9982) with a detection limit of 15 μM. Some common interferents like glucose, ascorbic acid and uric acid did not cause any interference, due to the use of a low operating potential. The FG/Gr electrode exhibits good electrocatalytic activity towards hydrogen peroxide (H(2)O(2)). A wide linear response to H(2)O(2) ranging from 0.5 to 7 mM (R=-0.9967) with a sensitivity of 443.25 μA mM(-1) cm(-2) has been obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. TH-AB-202-02: Real-Time Verification and Error Detection for MLC Tracking Deliveries Using An Electronic Portal Imaging Device

    International Nuclear Information System (INIS)

    J Zwan, B; Colvill, E; Booth, J; J O’Connor, D; Keall, P; B Greer, P

    2016-01-01

    Purpose: The added complexity of the real-time adaptive multi-leaf collimator (MLC) tracking increases the likelihood of undetected MLC delivery errors. In this work we develop and test a system for real-time delivery verification and error detection for MLC tracking radiotherapy using an electronic portal imaging device (EPID). Methods: The delivery verification system relies on acquisition and real-time analysis of transit EPID image frames acquired at 8.41 fps. In-house software was developed to extract the MLC positions from each image frame. Three comparison metrics were used to verify the MLC positions in real-time: (1) field size, (2) field location and, (3) field shape. The delivery verification system was tested for 8 VMAT MLC tracking deliveries (4 prostate and 4 lung) where real patient target motion was reproduced using a Hexamotion motion stage and a Calypso system. Sensitivity and detection delay was quantified for various types of MLC and system errors. Results: For both the prostate and lung test deliveries the MLC-defined field size was measured with an accuracy of 1.25 cm 2 (1 SD). The field location was measured with an accuracy of 0.6 mm and 0.8 mm (1 SD) for lung and prostate respectively. Field location errors (i.e. tracking in wrong direction) with a magnitude of 3 mm were detected within 0.4 s of occurrence in the X direction and 0.8 s in the Y direction. Systematic MLC gap errors were detected as small as 3 mm. The method was not found to be sensitive to random MLC errors and individual MLC calibration errors up to 5 mm. Conclusion: EPID imaging may be used for independent real-time verification of MLC trajectories during MLC tracking deliveries. Thresholds have been determined for error detection and the system has been shown to be sensitive to a range of delivery errors.

  3. Coating, Degrading and Testing of Organic Polymer Devices - Reducing the route from Laboratory to Production scale devices

    DEFF Research Database (Denmark)

    Dam, Henrik Friis

    volume, which for spin coating allowed making a single 1 cm2 device, using the mini roll coater (MRC) enable the coating of a 100 cm2 area, resulting in 60 1cm2 devices with the present mask designs. With the relative expensive polymers, this translates into a large saving for performing the same amount...

  4. Growth and yield of the sweet cherry ( Prunus avium L.) as affected ...

    African Journals Online (AJOL)

    Three different training systems (Spanish bush, Spindle bush and "V") were compared. The smaller vegetative growth, expressed as trunk crosssectional area (TCSA) was recorded in Spanish bush (34.68 cm2) when compared to Spindle bush (40.11 cm2) and "V" (40.82 cm2). The largest cumulative yield per hectare was ...

  5. Solving the Fokker-Planck equation on a massively parallel computer

    International Nuclear Information System (INIS)

    Mirin, A.A.

    1990-01-01

    The Fokker-Planck package FPPAC had been converted to the Connection Machine 2 (CM2). For fine mesh cases the CM2 outperforms the Cray-2 when it comes to time-integrating the difference equations. For long Legendre expansions the CM2 is also faster at computing the Fokker-Planck coefficients. 3 refs

  6. Record mobility in transparent p-type tin monoxide films and devices by phase engineering

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso; Nayak, Pradipta K.; Al-Jawhari, Hala A.; Bianchi Granato, Danilo; Schwingenschlö gl, Udo; Alshareef, Husam N.

    2013-01-01

    developed SnO thin films with a Hall mobility of 18.71 cm2 V-1 s-1 and fabricated TFT devices with a linear field-effect mobility of 6.75 cm2 V-1 s -1 and 5.87 cm2 V-1 s-1 on transparent rigid and translucent flexible substrates, respectively. These values

  7. Electrical and chemical stimulation of the same hypothalamic loci in relation to agressive behaviour in cats: a comparison study.

    Science.gov (United States)

    Bhatia, S C; Manchanda, S K; Kapoor, B K; Aneja, I S

    1995-10-01

    Chemitrodes which permit electrical and chemical stimulation of the same hypothalamic loci were implanted in anterior hypothalamic and preoptic regions. These sites were stimulated electrically using biphasic square wave pulse (1 ms, 60 Hz) at a current strength ranging from 150-800 microA to evoke an aggressive response. At lower current strength of 150-200 micro A, defence response, a sort of non-specific response can be elicited from these regions. Increasing the current strength to 400 microA led to the recruitment of affective and somatic components and changed the response pattern either to affective attack or flight. The loci producing affective attack response were localized more laterally and ventrally while the loci producing flight response were located in the dorsomedial regions of the hypothalamus. In this response the animal made a goal-directed attempt to escape through an escape route. Increasing the current strength to 500 microA in the dorsomedial regions changed the flight response to violent flight, which involved vigorous running with unsheathed claws and attacking objects if obstructed. Similar increase in current strength at loci producing affective attack only led to a decrease in the latency of response and made the attack more vigorous. Microinfusion of carbachol in graded doses of 2-15 microgram at all these loci produced a profound affective display. At lower doses of 2 and 5 microgram, only some components of affective display like alertness, pupillary dilation and ear flatness were exhibited. Increasing the dose to 10 micrograms and 15 micrograms led to the recruitment of other affective components like piloerection, salivation, hissing and baring of teeth. Microinfusion of carbachol at all loci producing affective attack on electrical stimulation produced a prononced affective display while microinfusion of carbachol at loci producing flight response led to the development of defence posture. At six loci a typical flight response was

  8. Performing daily prostate targeting with a standard V-EPID and an automated radio-opaque marker detection algorithm

    International Nuclear Information System (INIS)

    Beaulieu, Luc; Girouard, Louis-Martin; Aubin, Sylviane; Aubry, Jean-Francois; Brouard, Lucie; Roy-Lacroix, Lise; Dumont, Jean; Tremblay, Daniel; Laverdiere, Jacques; Vigneault, Eric

    2004-01-01

    Online prostate positioning using gold markers and a standard video-based electronic portal imaging device is reported. The average systematic (random) errors have been reduced from 2.1 mm (2.7 mm) to 0.5 mm (1.5 mm) in AP direction, 1.1 mm (1.7 mm) to 0.7 mm (1.2 mm) SI and 1.2 mm (1.7 mm) to 0.6 mm (1.3 mm) LR

  9. Bounding Radionuclide Inventory and Accident Consequence Calculation for the 1L Target

    International Nuclear Information System (INIS)

    Kelsey, Charles T. IV

    2011-01-01

    A bounding radionuclide inventory for the tungsten of the Los Alamos Neutron Science Center (LANSCE) IL Target is calculated. Based on the bounding inventory, the dose resulting from the maximum credible incident (MCI) is calculated for the maximally exposed offsite individual (MEOl). The design basis accident involves tungsten target oxidation following a loss of cooling accident. Also calculated for the bounding radionuclide inventory is the ratio to the LANSCE inventory threshold for purposes of inventory control as described in the target inventory control policy. A bounding radionuclide inventory calculation for the lL Target was completed using the MCNPX and CINDER'90 codes. Continuous beam delivery at 200 (micro)A to 2500 mA·h was assumed. The total calculated activity following this irradiation period is 205,000 Ci. The dose to the MEOI from the MCI is 213 mrem for the bounding inventory. The LANSCE inventory control threshold ratio is 132.

  10. Negotiation style, speech accommodation, and small talk in Sino-Western business negotiations: A Hong Kong case study

    DEFF Research Database (Denmark)

    Ladegaard, H. J.

    2011-01-01

    This article analyzes authentic negotiation encounters between a Danish buyer and several predominantly Chinese sellers at a jewelry fair in China. Three recurring themes were identified in the data: different negotiation styles (a preference for an indirect mitigated style in the Chinese...... viability without loss of face. The article acknowledges that claims about the importance of negotiators' cultural backgrounds need to be demonstrated rather than presumed, but it also argues that an analysis of predominant Chinese cultural value systems (such as face and the guanxi-concept) is likely...... to lead to a deeper and more comprehensive understanding of Sino-Western negotiations. The article advocates a combination of in-depth discourse analysis and studies of micro-as well as macro-contextual value and norms - i.e., a truly pragmatic approach to cross-cultural encounters - as the way forward...

  11. Possibilities for Beam Stripping Solutions at a Rare Isotope Accelerator (RIA)

    International Nuclear Information System (INIS)

    Greife, Uwe

    2006-01-01

    As part of the DOE RIA R and D effort we investigated the possibilities and problems of beam strippers in the different heavy ion accelerator components of a possible Rare Isotope Accelerator (RIA) facility. We focused on two beam stripping positions in the RIA heavy ion driver where benchmark currents of up to 5 particle (micro)A 238-U were projected at energies of 10.5 MeV/u and 85 MeV/u respectively. In order to select feasible stripper materials, data from experiments with Uranium beams at Texas A and M and GSI were evaluated. Based on these results thermal estimates for a possible design were calculated and cooling simulations with commercially available software performed. Additionally, we performed simulations with the GEANT4 code on evaluating the radiation environment for our beam stripping solution at the 85 MeV/u position in the RIA driver

  12. The behaviour of the charging system of the Vivitron for the first voltage tests

    International Nuclear Information System (INIS)

    Helleboid, J.M.

    1992-06-01

    The charging system used for the initial commissioning of the Vivitron generator is a simplified temporary version of the final one. As the belt runs in a largely open structure performances could be possibly limited compared with the final design. The observed behaviour for the first high voltage tests was quite satisfying apart from the excessive parasitic currents at the rollers. That led us to study and test many solutions up to the point that a humidity level much higher than thought was discovered as the most probable cause of the problem. The further tests brought the confirmation as the parasitic currents at the supporting rollers not exceeded tens of microA under dry conditions as it had first been expected from the experimental design studies

  13. Potentiation by choline of basal and electrically evoked acetylcholine release, as studied using a novel device which both stimulates and perfuses rat corpus striatum

    Science.gov (United States)

    Farber, S. A.; Kischka, U.; Marshall, D. L.; Wurtman, R. J.

    1993-01-01

    We examined the release of acetylcholine (ACh) and dopamine (DA) using a novel probe through which striatal neurons could be both superfused and stimulated electrically in both anesthetized and freely moving awake animals. Optimal stimulation parameters for eliciting ACh release from cholinergic neurons differed from those required for eliciting DA release from dopaminergic terminals: at 0.6 ms pulse duration, 20 Hz and 200 microA, ACh release increased to 357 +/- 30% (P basal release rose from 117 +/- 7% to 141 +/- 5% of initial baseline levels (P basal or evoked DA release although neostigmine (10 microM) significantly elevated basal DA release (from 36.7 fmol/10 min to 71.5 fmol/10 min; P basal (from 106 +/- 7% to 154 +/- 17%; P < 0.05) and electrically evoked (from 146 +/- 13 to 262 +/- 16%; P < 0.01) ACh release.(ABSTRACT TRUNCATED AT 250 WORDS).

  14. An all-solid-state lithium/polyaniline rechargeable cell

    Science.gov (United States)

    Li, Changzhi; Peng, Xinsheng; Zhang, Borong; Wang, Baochen

    1992-07-01

    The performance of an all-solid-state cell having a lithium negative electrode, a modified polyethylene oxide (PEO)-epoxy resin (ER) electrolyte, and a polyaniline (PAn) positive electrode has been studied using cyclic voltammetry, charge/discharge cycling, and polarization curves at various temperatures. The redox reaction of the PAn electrode at the PAn/modified PEO-ER interface exhibits good reversibility. At 50-80 C, the Li/PEO-ER-LiClO4/PAn cell shows more than 40 charge/discharge cycles, 90 percent charge/discharge efficiency, and 54 W h kg discharge energy density (on PAn weight basis) at 50 micro-A between 2 and 4 V. The polarization performance of the battery improves steadily with increase in temperature.

  15. Injector for CESAR (2 MeV electron storage ring): 2-beam, 2 MV van de Graaff generator.

    CERN Multimedia

    CERN PhotoLab

    1963-01-01

    The van de Graaff generator in its tank. For voltage-holding, the tank was filled with pressurized extra-dry nitrogen. 2 beams emanated from 2 separate electron-guns. The left beam, for injection into the CESAR ring, was pulsed at 50 Hz, with currents of up to 1 A for 400 ns. The right beam was sent to a spectrometer line. Its pulselength was also 400 ns, but the pulse current was 12 microA, at a rate variable from 50 kHz to 1 MHz. This allowed stabilization of the top-terminal voltage to an unprecedented stability of +- 100 V, i.e. 6E-5. Although built for a nominal voltage of 2 MV, the operational voltage was limited to 1.75 MV in order to minimize voltage break-down events.

  16. Electric currents induced by twisted light in Quantum Rings.

    Science.gov (United States)

    Quinteiro, G F; Berakdar, J

    2009-10-26

    We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

  17. Overview of progress on the improvement projects for the LANSCE accelerator and target facilities

    International Nuclear Information System (INIS)

    Macek, R.J.; Browne, J.; Brun, T.; Donahue, J.B.; Fitzgerald, D.H.; Hoffman, E.; Pynn, R.; Schriber, S.; Weinacht, D.

    1997-01-01

    Three projects have been initiated since 1994 to improve the performance of the accelerator and target facilities for the Los Alamos Neutron Science Center (LANSCE). The LANSCE Reliability Improvement Project (LRIP) was separated into two phases. Phase 1, completed in 1995, targeted near-term improvements to beam reliability and availability that could be completed in one-year's time. Phase 2, now underway and scheduled for completion in May 1998, consists of two projects: (a) implementation of direct H-injection for the Proton Storage Ring (PSR) and (b) an upgrade of the target/moderator system for the short pulse spallation neutron (SPSS) source. The latter will reduce the target change-out time from about 10 months to about three weeks. The third project, the SPSS Enhancement Project, is aimed at increasing the PSR output beam current to 200 microA at 30 Hz and providing up to seven new neutron scattering instruments

  18. A Carbon Nanotube Electron Source Based Ionization Vacuum Gauge

    Energy Technology Data Exchange (ETDEWEB)

    Changkun Dong; Ganapati Myneni

    2003-10-01

    The results of fabrication and performance of an ionization vacuum gauge using a carbon nanotube (CNT) electron source are presented. The electron source was constructed with multi-wall nanotubes (MWNT), which were grown using thermal chemical vapor deposition (CVD) process. The electron emission of the source was stable in vacuum pressure up to 10-7 Torr, which is better than the metal field emitters. The measurement linearity of the gauge was better than {+-}10% from 10-6 to 10-10 Torr. The gauge sensitivity of 4 Torr-1 was achieved under 50 {micro}A electron emission in nitrogen. The gauge is expected to find applications in vacuum measurements from 10-7 Torr to below 10-11 Torr.

  19. Examination of disks from the IPNS depleted uranium target

    International Nuclear Information System (INIS)

    Strain, R.V.; Carpenter, J.M.

    1995-10-01

    This report describes the results of examining the Zircaloy-2 clad depleted uranium disks from the Intense Pulse Neutron Source (IPNS) Target. That target operated from August, 1981 to June, 1988 and from September, 1991 to September, 1992 at 450 MeV, pulsing at 30 Hz with a time average proton current of about 15 microA. The target was removed from service when the presence of fission products ( 135 Xe) in the coolant cover gas indicated a failure in the Zircaloy-2 cladding. Altogether, the target had absorbed about 240 mA hours of proton current, and endured between 50,000 and 100,000 thermal cycles. The purpose of the examination was to assess the condition of the disks and determine the cause of the cladding failure. The results of visual, gamma ray scanning, and destructive metallurgical examination of two disks are described

  20. Biological effects of 2450 MHZ microwave radiation on Raji-Cell in vitro

    International Nuclear Information System (INIS)

    Tan Ming; Zhang Mengdan; Xu Hao.

    1988-01-01

    A water circulating microwave exposure system designed by the authors was used to investigate the thermal and nonthermal biological effects at different power density (1.0mw/cm 2 , 3.9mw/cm 2 , 6.2mw/cm 2 , 8.3mw/cm 2 , 10.5mw/cm 2 ). The results show that the growth of Raji-Cell is inhibited significantly by microwave exposure in 8.3 mw/cm 2 and 10.5 mw/cm 2 groups in temperature controlled test (below 37.0 deg C). It shows that while the growth curve goes down, the rate of inhibition and time of generation increase. The degree of inhibition would increase when the medium temperature was not controlled. And, the mechanisms of thermal and nonthermal biological effects were discussed

  1. Influence of internal current and pacing current on pacemaker longevity.

    Science.gov (United States)

    Schuchert, A; Kuck, K H

    1994-01-01

    The effects of lower pulse amplitude on battery current and pacemaker longevity were studied comparing the new, small-sized VVI pacemaker, Minix 8341, with the former model, Pasys 8329. Battery current was telemetrically measured at 0.8, 1.6, 2.5, and 5.0 V pulse amplitude and 0.05, 0.25, 0.5, and 1.0 msec pulse duration. Internal current was assumed to be equal to the battery current at 0.8 V and 0.05 msec. Pacing current was calculated subtracting internal current from battery current. The Minix pacemaker had a significantly lower battery current because of a lower internal current (Minix: 4.1 +/- 0.1 microA; Pasys: 16.1 +/- 0.1 microA); pacing current of both units was similar. At 0.5 msec pulse duration, the programming from 5.0-2.5 V pulse amplitude resulted in a greater relative reduction of battery current in the newer pacemaker (51% vs 25%). Projected longevity of each pacemaker was 7.9 years at 5.0 V and 0.5 msec. The programming from 5.0-2.5 V extended the projected longevity by 2.3 years (Pasys) and by 7.1 years (Minix). The longevity was negligibly longer after programming to 1.6 V. extension of pacemaker longevity can be achieved with the programming to 2.5 V or less if the connected pacemakers need a low internal current for their circuitry.

  2. Pupil constriction evoked in vitro by stimulation of the oculomotor nerve in the turtle (Trachemys scripta elegans).

    Science.gov (United States)

    Dearworth, James R; Brenner, J E; Blaum, J F; Littlefield, T E; Fink, D A; Romano, J M; Jones, M S

    2009-01-01

    The pond turtle (Trachemys scripta elegans) exhibits a notably sluggish pupillary light reflex (PLR), with pupil constriction developing over several minutes following light onset. In the present study, we examined the dynamics of the efferent branch of the reflex in vitro using preparations consisting of either the isolated head or the enucleated eye. Stimulation of the oculomotor nerve (nIII) using 100-Hz current trains resulted in a maximal pupil constriction of 17.4% compared to 27.1% observed in the intact animal in response to light. When current amplitude was systematically increased from 1 to 400 microA, mean response latency decreased from 64 to 45 ms, but this change was not statistically significant. Hill equations fitted to these responses indicated a current threshold of 3.8 microA. Stimulation using single pulses evoked a smaller constriction (3.8%) with response latencies and threshold similar to that obtained using train stimulation. The response evoked by postganglionic stimulation of the ciliary nerve using 100-Hz trains was largely indistinguishable from that of train stimulation of nIII. However, application of single-pulse stimulation postganglionically resulted in smaller pupil constriction at all current levels relative to that of nIII stimulation, suggesting that there is amplification of efferent drive at the ganglion. Time constants for constrictions ranged from 88 to 154 ms with relaxations occurring more slowly at 174-361 ms. These values for timing from in vitro are much faster than the time constant 1.66 min obtained for the light response in the intact animal. The rapid dynamics of pupil constriction observed here suggest that the slow PLR of the turtle observed in vivo is not due to limitations of the efferent pathway. Rather, the sluggish response probably results from photoreceptive mechanisms or central processing.

  3. Demonstration of iodine K-edge imaging by use of an energy-discrimination X-ray computed tomography system with a cadmium telluride detector.

    Science.gov (United States)

    Abudurexiti, Abulajiang; Kameda, Masashi; Sato, Eiichi; Abderyim, Purkhet; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2010-07-01

    An energy-discrimination K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region by utilizing contrast media. The CT system has a cadmium telluride (CdTe) detector, and a projection curve is obtained by linear scanning with use of the CdTe detector in conjunction with an X-stage. An object is rotated by a rotation step angle with use of a turntable between the linear scans. Thus, CT is carried out by repetition of the linear scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced with use of charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. For performing energy discrimination, a low-dose-rate X-ray generator for photon counting was developed; the maximum tube voltage and the minimum tube current were 110 kV and 1.0 microA, respectively. In energy-discrimination CT, the tube voltage and the current were 60 kV and 20.0 microA, respectively, and the X-ray intensity was 0.735 microGy/s at 1.0 m from the source and with a tube voltage of 60 kV. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selection of photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  4. [Universal electrogustometer EG-1].

    Science.gov (United States)

    Pleskacz, Witold A; Wałkanis, Andrzej; Rapiejko, Piotr; Jurkiewicz, Dariusz

    2009-01-01

    Electrogustometry has been used as a clinical tool for diagnosis and assessment of a variety of conditions. Since the lack of versatile electrogustometer for research and diagnosis, the new electrogustometer EG-1 was developed in 2006. It was done in cooperation between Warsaw University of Technology and Military Institute of Medicine in Warsaw. EG-1 allows quantitative estimation of taste perception threshold using both static and impulse electrogustometry with bipolar electrode. It is a fully autonomous, battery powered and portable instrument. Because of small size and weight, it can be easily placed in any environment. Microprocessor controlled measurement system and user-friendly interface (LCD display with simple keyboard) make EG-1 electrogustometer very handy and flexible in operation. Data obtained during measurements is stored in the internal device memory. After taste examinations measurement data can be transferred to a personal computer via inbuilt USB port for further analysis and storage. EG-1 can generate three predefined variously shaped current impulses: sinus-, saw- and rectangle-shaped. There is an optional possibility of creating own shapes of stimulus puls by the user. The electrical parameters of generated pulses are as follow: current amplitude 1-2000 microA regulated with 1 microA step, stimulus frequency 0(DC)-500 Hz regulated with 5 Hz step, controlable fulfillment factor and signal rise time (optional for automatic measurements). The operator can trigger the stimuli via a hand switch on the bipolar electrode (with gold-plated endings), via keyboard or via additional independent hand switch. Three years of experience collected during EG-1 exploitation allowed to design a new version of electrogustometer EG-2 with a touch panel and color graphical display.

  5. Analysis of Etched CdZnTe Substrates

    Science.gov (United States)

    Benson, J. D.; Bubulac, L. O.; Jaime-Vasquez, M.; Lennon, C. M.; Arias, J. M.; Smith, P. J.; Jacobs, R. N.; Markunas, J. K.; Almeida, L. A.; Stoltz, A.; Wijewarnasuriya, P. S.; Peterson, J.; Reddy, M.; Jones, K.; Johnson, S. M.; Lofgreen, D. D.

    2016-09-01

    State-of-the-art as-received (112)B CdZnTe substrates have been examined for surface impurity contamination and polishing residue. Two 4 cm × 4 cm and one 6 cm × 6 cm (112)B state-of-the-art as-received CdZnTe wafers were analyzed. A maximum surface impurity concentration of Al = 1.7 × 1015 atoms cm-2, Si = 3.7 × 1013 atoms cm-2, Cl = 3.12 × 1015 atoms cm-2, S = 1.7 × 1014 atoms cm-2, P = 1.1 × 1014 atoms cm-2, Fe = 1.0 × 1013 atoms cm-2, Br = 1.2 × 1014 atoms cm-2, and Cu = 4 × 1012 atoms cm-2 was observed on the as-received CdZnTe wafers. CdZnTe particulates and residual SiO2 polishing grit were observed on the surface of the as-received (112)B CdZnTe substrates. The polishing grit/CdZnTe particulate density on CdZnTe wafers was observed to vary across a 6 cm × 6 cm wafer from ˜4 × 107 cm-2 to 2.5 × 108 cm-2. The surface impurity and damage layer of the (112)B CdZnTe wafers dictate that a molecular beam epitaxy (MBE) preparation etch is required. The contamination for one 4 cm × 4 cm and one 6 cm × 6 cm CdZnTe wafer after a standard MBE Br:methanol preparation etch procedure was also analyzed. A maximum surface impurity concentration of Al = 2.4 × 1015 atoms cm-2, Si = 4.0 × 1013 atoms cm-2, Cl = 7.5 × 1013 atoms cm-2, S = 4.4 × 1013 atoms cm-2, P = 9.8 × 1013 atoms cm-2, Fe = 1.0 × 1013 atoms cm-2, Br = 2.9 × 1014 atoms cm-2, and Cu = 5.2 × 1012 atoms cm-2 was observed on the MBE preparation-etched CdZnTe wafers. The MBE preparation-etched surface contamination consists of Cd(Zn)Te particles/flakes. No residual SiO2 polishing grit was observed on the (112)B surface.

  6. The Study of Tissue Dose Perturbation by Air Cavity with 6MV Photon Beam

    International Nuclear Information System (INIS)

    Shin, Byung Chul; Yoo, Myung Jin; Moon, Chang Woo; Jeung, Tae Sig; Yum, Ha Yong

    1995-01-01

    Purpose : To determine the perturbation effect in the tissue downstream from surface layers of lesions located in the air/tumor-tissue interface of larynx using 6MV photon beam. Materials and Methods : Thermoluminescent dosimeters(TLDs). Were embedded at 3 measurement locations in slab no.7 of a humanoid phantom and exposed to forward and backward direction using various field sizes(4 X 4cm 2 - 15 X 15 cm 2 ). Results : At the air/tissue interface, forward dose perturbation factor(FDPF) is about 1.085 with 4 X 4 cm 2 , 1.05 with 7 X 7 cm 2 , 1.048 with 10 X 10 cm 2 , and 1.041 with 15 X 15 cm 2 . Backscatter dose perturbation factor(BDPF) is about 0.99 with 4 X 4 cm 2 , 0.981 with 7 X 7 cm 2 , 0.956 with 10 X 10 cm 2 and 0.97 with 15 X 15 cm 2 . Conclusion : FDPF is greater as field size is smaller. And FDPF is smaller as the distance is further from the air/tissue interface

  7. Sifat Fisik Daging Sapi, Kerbau dan Domba pada Lama Postmortem yang Berbeda (Physical Characteristics of Beef, Buffalo and Lamb Meat on Different Postmortem Periods

    Directory of Open Access Journals (Sweden)

    Komariah (Komariah

    2012-02-01

    buffalo meat and lamb. The mean shear force of beef (6.73±0.16 kg/cm2 and buffalo meat (6.53±0.38 kg/cm2 were significantly (P<0.05 higher than lamb (5.24±0.93 kg/cm2. (Key words: Physical characteristic, Postmortem, Beef, Buffalo, and Lamb meat

  8. Preparation of barium and uranium targets on thick backings

    International Nuclear Information System (INIS)

    Sletten, G.

    1982-01-01

    Targets of 135 Ba and 235 U have been prepared by the technique of heavy ion sputtering. Rolled foils of 208 Pb and 197 Au were used to support 250-500 μg/cm 2 layers of barium. Uranium films have been prepared by sputtering UO 2 onto 1 mg/cm 2 titanium foils. Uranium deposit thicknesses of 300 to 1800 μg/cm 2 have been prepared. (orig.)

  9. Large-area thin self-supporting carbon foils with MgO coatings

    Science.gov (United States)

    Stolarz, Anna; Maier-Komor, Peter

    2002-03-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 μg/cm 2, coated with approximately 4 μg/cm 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  10. 10 CFR 71.4 - Definitions.

    Science.gov (United States)

    2010-01-01

    ... § 71.15. Graphite means, for the purposes of §§ 71.15 and 71.22, graphite with a boron equivalent... exceed 2 × 10−3 A2/g. Low toxicity alpha emitters means natural uranium, depleted uranium, natural... microcurie/cm2) for beta and gamma and low toxicity alpha emitters, or 0.4 Bq/cm2 (10−5 microcurie/cm2) for...

  11. Horizontal infiltration and trace element measurements for ...

    African Journals Online (AJOL)

    Laboratory investigations of horizontal infiltration were carried out on three Zaria soils (Samaru, Tudun Wada and the Kubanni river basin Fadama wet-land soils) in Nigeria, which are principally alfisols. Diffusivity was found to be -77.5 x 10 -2 cm 2 s-1, -8.4 x 10 -2 cm 2 s-1 and -117.0 x 10 -2 cm 2 s-1 respectively for the ...

  12. Next-generation Surface Enhanced Raman Scattering (SERS) Substrates for Hazard Detection

    Science.gov (United States)

    2012-09-01

    substrates at differing concentrations ranging from 0.05 ug/cm2 to 50 ug/cm2. These concentrations were independently validated by UV -Vis...standard Klarite substrates at a concentration of 5.0 ug/cm2. The concentration jetted was validated using a secondary UV -Vis technique.(20, 81) After... Spectros ., 994 (1997). [58] Alexander, T.A., Le, D.M., "Characterization of a commercialized SERS-active substrate and its application to the

  13. Extra-high short-circuit current for bifacial solar cells in sunny and dark-light conditions.

    Science.gov (United States)

    Duan, Jialong; Duan, Yanyan; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2017-09-05

    We present here a symmetrically structured bifacial solar cell tailored by two fluorescent photoanodes and a platinum/titanium/platinum counter electrode, yielding extra-high short-circuit current densities as high as 28.59 mA cm -2 and 119.9 μA cm -2 in simulated sunlight irradiation (100 mW cm -2 , AM1.5) and dark-light conditions, respectively.

  14. XPS and SIMS study of aluminium native oxide modifications induced by Q-switched Nd :YAG laser treatment

    CSIR Research Space (South Africa)

    Barnier, V

    2006-04-01

    Full Text Available with fluences between 0.7 and 1.7 J/cm2, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) revealed thermal oxidation with an increase of the oxide-layer thickness for 0.7–1.3 J/cm2. Above a threshold at about 1.3 J/cm2 the oxide...

  15. Butyrate absorption and lactate secretion in ulcerative colitis

    DEFF Research Database (Denmark)

    Hove, H; Holtug, K; Jeppesen, P B

    1995-01-01

    .12. Despite normal butyrate absorption, sodium absorption was compromised in active ulcerative colitis (11.5 +/- 1.4 mumol/cm2/h) compared with quiescent (15.4 +/- 1.0 mumol/cm2/h) and controls (18.7 +/- 0.8 mumol/cm2/h) (P = 0.0006). Mucosal secretion of L-lactate was minimal in both healthy controls...

  16. Pusher curving technique for preventing tilt of femoral Geunther Tulip inferior vena cava filter: in vitro study

    International Nuclear Information System (INIS)

    Xiao Liang; Shen Jing; Huang Desheng; Xu Ke

    2011-01-01

    Objective: To determine whether the adjustment of the pusher of GTF was useful to decrease the degree of tilting of the femoral Geunther Tulip filter (GTF) in an in vitro caval model. Methods: The caval model was constructed by placement of a 25 mm × 100 mm and two 10 mm × 200 mm Dacron graft inside a transparent bifurcate glass tube. The study consisted of two groups: left straight group (GLS) (n = 100) and left curved group (G LC ) (n=100). In the G LC , a 10° to 20° angle was curved on the introducer. The distance (D CH ) between the caval right wall and the hook was measured. The degree of tilting (DT) was classified into 5 grades and recorded. Before and after the GTF being released, the angle (A CM1,2 ) between the axis of IVC and the metal mount, the distance (D CM1 ) between the caval right wall and the metal mount, the angle (ACF) between the axis of IVC and the axis of the filter and the diameter of IVC (D IVC ) were measured. The data were analyzed with Chi-Square test, t test, rank sum. test and Pearson correlation test. Results: The degree of GTF tilting in each group revealed a divergent tendency. In group LC , the apex of the filter tended to be grade Ⅲ compared in group LS (χ 2 value 37.491, P LS and G LC were considered as statistical significance (16.60° vs. 3.05°, 20.60° vs. 3.50°, -3.90° vs. -0.40°, 2.98 mm vs. 10.40 mm, -10.95° vs. -0.485°, 13.17 mm vs. 10.06 mm, -1.70° vs. 0.70°, t or Z values -12.187, -12.188, -8.545, -51.834, -11.395, 9.562, -3.596, P CM1 and A CF , A CM1 - A CM2 and D CH1 - D CH2 in each group, respectively (r values 0.978, 0.344, 0.879, 0.627, P CH1 and A CF in each group, A CP and A CF in group LC (r values -0.974, -0.322, -0.702, P CM1 and A CF , A CM1 - A CM2 and D CH1 - D CH2 in each group, respectively (r values 0.978, 0.344, 0.879, 0.627, P CH1 and A CF in each group, A CP and A CF in group LC (r values -0.974, -0.322, -0.702, P<0.01). Conclusion: The technique of adjusting the orientation of filter

  17. Abutment region dosimetry for serial tomotherapy

    International Nuclear Information System (INIS)

    Low, Daniel A.; Mutic, Sasa; Dempsey, James F.; Markman, Jerry; Goddu, S. Murty; Purdy, James A.

    1999-01-01

    Purpose: A commercial intensity modulated radiation therapy system (Corvus, NOMOS Corp.) is presently used in our clinic to generate optimized dose distributions delivered using a proprietary dynamic multileaf collimator (DMLC) (MIMiC) composed of 20 opposed leaf pairs. On our accelerator (Clinac 600C/D, Varian Associates, Inc.) each MIMiC leaf projects to either 1.00 x 0.84 or 1.00 x 1.70 cm 2 (depending on the treatment plan and termed 1 cm or 2 cm mode, respectively). The MIMiC is used to deliver serial (axial) tomotherapy treatment plans, in which the beam is delivered to a nearly cylindrical volume as the DMLC is rotated about the patient. For longer targets, the patient is moved (indexed) between treatments a distance corresponding to the projected leaf width. The treatment relies on precise indexing and a method was developed to measure the precision of indexing devices. A treatment planning study of the dosimetric effects of incorrect patient indexing and concluded that a dose heterogeneity of 10% mm -1 resulted. Because the results may be sensitive to the dose model accuracy, we conducted a measurement-based investigation of the consequences of incorrect indexing using our accelerator. Although the indexing provides an accurate field abutment along the isocenter, due to beam divergence, hot and cold spots will be produced below and above isocenter, respectively, when less than 300 deg. arcs were used. A preliminary study recently determined that for a 290 deg. rotation in 1 cm mode, 15% cold and 7% hot spots were delivered to 7 cm above and below isocenter, respectively. This study completes the earlier work by investigating the dose heterogeneity as a function of position relative to the axis of rotation, arc length, and leaf width. The influence of random daily patient positioning errors is also investigated. Methods and Materials: Treatment plans were generated using 8.0 cm diameter cylindrical target volumes within a homogeneous rectilinear film

  18. Glove use among hairdressers

    DEFF Research Database (Denmark)

    Oreskov, Katia W; Søsted, Heidi; Johansen, Jeanne D

    2015-01-01

    by each person, interrupted by a demonstration of how to use gloves correctly. Photographs were taken to compare UV contamination before and after the demonstration. RESULTS: All of the participants (100%) had their hands contaminated during the first round; the area ranged between 0.02 and 101.37 cm(2......) (median 3.62 cm(2)). In the second round, 55.8% were contaminated (range 0.00-3.08 cm(2) ; median 0.01 cm(2)). The reduction in contaminated skin areas was statistically significant (p 

  19. Studies on the influence of laser beams on wound granulation

    International Nuclear Information System (INIS)

    Brunner, R.

    1982-01-01

    The influence of laser light of law energy on wound healing was tested on 204 rats in a blind study. The growth of granulation tissue in a polyvinylchloride cylinder implanted on the backs of the animals served as parameter for wound healing. Irradiation was carried out with a helium-neon laser (wavelength 632.8 nm) at daily doses of 0.5 J/cm 2 , 1.5 J/cm 2 , 4 J/cm 2 , 10 J/cm 2 and 20 J/cm 2 , and with incoherent non-linear polarized red light (wavelength 630 nm) with a daily dose of 4 J/cm 2 . This was repeated 8 times. Laser irradiation caused a statistically significant increase in wet and dry granulation tissue weight of 25% in the dose range 1.5 J/cm 2 to 20 J/cm 2 . At 0.5 J/cm 2 the effect was less, but the least effect was achieved by non-linear polarized incoherent red light. Bacteriological evaluation of wound germ counts revealed a marginally lower presence of high germ cell densities. In irradiated animals, histological and enzyme cytochemical findings revealed, in addition to a significant findings revealed, in addition to a significant increase in mast cells, a smaller increase in fibroblast count and a slight decrease in granulocytic and histiocytic elements. The biochemical evaluation of granulation tissue revealed no differences in collagen content between irradiated and unirradiated animals. (orig.) [de

  20. Leaching of nuclear power reactor waste forms

    International Nuclear Information System (INIS)

    Endo, L.S.; Villalobos, J.P.; Miyamoto, H.

    1987-01-01

    The leaching tests for immobilized power reactor wastes carried out at IPEN are described. These wastes forms consist mainly of spent resins and boric acid concentrates solidified in ordinary Portland cement. All tests were conducted according to the ISO and IAEA recommendations. Three years leaching results are reported. The cesium diffuvity coefficients determined out of these results are about 1 x 10 -8 cm 2 /s for boric acid waste form and 9 x 10 -9 cm 2 /s for ion-exchange resin waste. Strontium diffusivity coefficients found are about 3 x 10 -11 cm 2 /s and 9 x 10 -11 cm 2 /s respectively. (Author) [pt

  1. [The cross-sectional area of the median nerve by sonography in the diagnosis of carpal tunnel syndrome].

    Science.gov (United States)

    Sabag-Ruiz, Enrique; Higuera-Lugo, Cirilo Omar; Ornelas-Aguirre, José Manuel; Gómez-Alcalá, Alejandro V

    2009-01-01

    To measure the median nerve cross-sectional area (MNCSA) at the carpal tunnel (CT) level by sonography (S) in a Mexican population. A comparative cross-sectional design study with a nonprobabilistic sampling with 50 women and 50 men in good health were submitted for measuring MNCSA at the level of the CT. Other variables like sex; side and degree of daily hand activity were also studied. The analysis was made by descriptive statistics, and Mann-Whitney U or Kruskal-Wallis tests. The mean MNCSA was 0.063 +/- 0.015 cm(2), in women; in men it was 0.072 +/- 0.018 cm(2); the difference was significant (p right side and 0.060 cm(2) in the left (90th percentile for both hands of 0.084 cm(2)); in men, it was of 0.070 cm(2) in the right hand and of 0.069 cm(2) in the left (90th percentile for both hands of 0.097 cm(2)). The difference between women and men was significant in each side, but not between right and left hands (p = 0.21). There was no correlation between age and MNCSA on either side, or with hand activity. A MNCSA value of 0.1 cm(2) for men and 0.09 cm(2) for women is proposed as a standard parameter for the Mexican population.

  2. Ethnic differences in mammographic densities: an Asian cross-sectional study.

    Science.gov (United States)

    Mariapun, Shivaani; Li, Jingmei; Yip, Cheng Har; Taib, Nur Aishah Mohd; Teo, Soo-Hwang

    2015-01-01

    Mammographic density is a strong risk factor for breast cancer and is highly variable, but, to date, few studies have examined density in Asian women, particularly those in low and middle-income Asian countries where genetic and lifestyle determinants may be significantly different. A total of 1,240 women who attended an opportunistic mammogram screening programme were eligible for analysis. Mammographic density was estimated using a fully-automated thresholding method and differences across ethnic groups were examined using linear regression in 205 randomly selected Chinese women, 138 Malay and 199 Indian women. Percent density was significantly higher in Chinese women (28.5%; 95% CI 27.0%, 30.0%) compared to Malay (24.2%; 95% CI 22.5%, 26.0%) and Indian (24.3%; 95% CI 22.8%, 25.7%) women (pChinese (72.2cm2; 95% CI 67.9cm2, 76.5cm2) women compared to Malay (92.1cm2; 95% CI 86.9cm2, 97.2cm2) and Indian (97.7cm2; 95% CI 93.4cm2, 101.9cm2) women (pChinese compared to Malay and Indian women in Malaysia. Known lifestyle determinants of mammographic density do not fully account for the ethnic variations observed in mammographic density in this Asian cohort.

  3. The effect of gold nanoparticles modified electrode on the glucose sensing performance

    Science.gov (United States)

    Zulkifli, Zulfa Aiza; Ridhuan, Nur Syafinaz; Nor, Noorhashimah Mohamad; Zakaria, Nor Dyana; Razak, Khairunisak Abdul

    2017-07-01

    In this work, 20 nm, 30 nm, 40 nm, 50 nm and 60 nm colloidal gold nanoparticles (AuNPs) were synthesized using the seeding growth method. AuNPs produced had spherical shape with uniform size. The AuNPs also are well dispersed in colloidal form that was proven by low polydispersity index. The produced AuNPs were used to modify electrode for glucose sensor. The produced AuNPs were deposited on indium tin oxide substrate (ITO), followed by immobilization of glucose oxidase (GOx) on it. After that, Nafion was deposited on the GOx/AuNPs/ITO. Electrooxidation of glucose with AuNPs-modified electrode was examined by cyclic voltammeter (CV) in 15 mM glucose mixed with 0.01 M PBS. The optimum size of AuNPs was 30 nm with optical density 3.0. AuNPs were successfully immobilized with glucose oxidase (GOx) and proved to work well as a glucose sensor. Based on the high electrocatalytic activity of Nafion/GOx/AuNPs/ITO, the sensitivity of the glucose sensors was further examined by varying the concentration of glucose solution from 2 mM to 20 mM in 0.01 M phosphate buffer solution (PBS) solution. Good linear relationship was observed between the catalytic current and glucose concentration in the range of 2 mM to 20 mM. The sensitivity of the Nafion/GOx/AuNPs/ITO electrode calculated from the slope of linear square calibration was 0.909 µA mM-1 cm-2 that is comparable with other published work. The linear fitting to the experimental data gives R-square of 0.991 at 0.9 V and a detection limit of 2.03 mM. This detection range is sufficient to be medically useful in monitoring human blood glucose level in which the normal blood glucose level is in the range of 4.4 to 6.6 mM and diabetic blood glucose level is above 7 mM.

  4. SU-F-T-672: A Novel Kernel-Based Dose Engine for KeV Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Reinhart, M; Fast, M F; Nill, S; Oelfke, U [The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom)

    2016-06-15

    Purpose: Mimicking state-of-the-art patient radiotherapy with high precision irradiators for small animals allows advanced dose-effect studies and radiobiological investigations. One example is the implementation of pre-clinical IMRT-like irradiations, which requires the development of inverse planning for keV photon beams. As a first step, we present a novel kernel-based dose calculation engine for keV x-rays with explicit consideration of energy and material dependencies. Methods: We follow a superposition-convolution approach adapted to keV x-rays, based on previously published work on micro-beam therapy. In small animal radiotherapy, we assume local energy deposition at the photon interaction point, since the electron ranges in tissue are of the same order of magnitude as the voxel size. This allows us to use photon-only kernel sets generated by MC simulations, which are pre-calculated for six energy windows and ten base materials. We validate our stand-alone dose engine against Geant4 MC simulations for various beam configurations in water, slab phantoms with bone and lung inserts, and on a mouse CT with (0.275mm)3 voxels. Results: We observe good agreement for all cases. For field sizes of 1mm{sup 2} to 1cm{sup 2} in water, the depth dose curves agree within 1% (mean), with the largest deviations in the first voxel (4%) and at depths>5cm (<2.5%). The out-of-field doses at 1cm depth agree within 8% (mean) for all but the smallest field size. In slab geometries, the mean agreement was within 3%, with maximum deviations of 8% at water-bone interfaces. The γ-index (1mm/1%) passing rate for a single-field mouse irradiation is 71%. Conclusion: The presented dose engine yields an accurate representation of keV-photon doses suitable for inverse treatment planning for IMRT. It has the potential to become a significantly faster yet sufficiently accurate alternative to full MC simulations. Further investigations will focus on energy sampling as well as calculation

  5. Novel Transparent Phosphor Conversion Matrix with High Thermal Conductivity for Next Generation Phosphor-Converted LED-based Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Bockstaller, Michael [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2017-02-06

    The low thermal conductivity of state-of-the-art polymer encapsulants (k ~ 0.15 Wm-1K-1) limits the efficiency and power density of current phosphor conversion light emitting diodes (pc-LEDs). The technical objective of this project was to demonstrate synthesis and processing schemes for the fabrication of polymer hybrid encapsulants with a thermal conductivity exceeding k = 0.4 Wm-1K-1 for LED applications. The ‘hybrid polymer’ approach encompasses the dispersion of high thermal conductivity particle fillers (zinc oxide, ZnO as well as the alpha-polymorph of alumina, Al2O3) within a polysiloxane matrix (poly(dimethylsiloxane), PDMS as well as poly(phenyl methyl siloxane), PPMS) to increase the thermal conductivity while maintaining optical transparency and photothermal stability at levels consistent with LED applications. To accomplish this goal, a novel synthesis method for the fabrication of nanosized ZnO particles was developed and a novel surface chemistry was established to modify the surface of zinc oxide particle fillers and thus to enable their dispersion in poly(dimethyl siloxane) (PDMS) matrix polymers. Molecular dynamics and Mie simulations were used to optimize ligand structure and to enable the concurrent mixing of particles in PDMS/PPMS embedding media while also minimizing the thermal boundary resistance as well as optical scattering of particle fillers. Using this approach the synthesis of PDMS/ZnO hybrid encapsulants exhibiting a thermal conductivity of 0.64 Wm-1K-1 and optical transparency > 0.7 mm-1 was demonstrated. A forming process based on micromolding was developed to demonstrate the forming of particle filled PDMS into film and lens shapes. Photothermal stability testing revealed stability of the materials for approximately 4000 min when exposed to blue light LED (450 nm, 30 W/cm2). One postgraduate and seven graduate students were supported by the project. The research performed within this project led to fifteen publications in peer

  6. SU-E-T-188: Commission of World 1st Commercial Compact PBS Proton System

    Energy Technology Data Exchange (ETDEWEB)

    Ding, X; Patel, B; Song, X; Syh, J; Syh, J; Zhang, J; Freund, D; Rosen, L; Wu, H [Willis-Knighton Medical Center, Shreveport, LA (United States)

    2015-06-15

    Purpose: ProteusONE is the 1st commercial compact PBS proton system with an upstream scanning gantry and C230 cyclotron. We commissioned XiO and Raystation TPS simultaneously. This is a summary of beam data collection, modeling, and verification and comparison without range shiter for this unique system with both TPS. Methods: Both Raystation and XiO requires the same measurements data: (i) integral depth dose(IDDs) of single central spot measured in water tank; (ii) absolute dose calibration measured at 2cm depth of water with mono-energetic 10×10 cm2 field with spot spacing 4mm, 1MU per spot; and (iii) beam spot characteristics in air at 0cm and ± 20cm away from ISO. To verify the beam model for both TPS, same 15 cube plans were created to simulate different treatment sites, target volumes and positions. PDDs of each plan were measured using a Multi-layer Ionization Chamber(MLIC), absolute point dose verification were measured using PPC05 in water tank and patient-specific QA were measured using MatriXX PT, a 2D ion chamber array. Results: All the point dose measurements at midSOBP were within 2% for both XiO and Raystation. However, up to 5% deviations were observed in XiO’s plans at shallow depth while within 2% in Raystation plans. 100% of the ranges measured were within 1 mm with maximum deviation of 0.5 mm. 20 patient specific plan were generated and measured in 3 planes (distal, proximal and midSOBP) in Raystation. The average of gamma index is 98.7%±3% with minimum 94% Conclusions: Both TPS were successfully commissioned and can be safely deployed for clinical use for ProteusONE. Based on our clinical experience in PBS planning, user interface, function and workflow, we preferably use Raystation as our main clinical TPS. Gamma Index >95% at 3%/3 mm criteria is our institution action level for patient specific plan QAs.

  7. Características fisicoquímicas de nueve híbridos de sorgo (Sorghum bicolor L. Moench y su relación con el contenido de almidón y digestión ruminal

    Directory of Open Access Journals (Sweden)

    Mariana Villarreal-Silva

    2015-01-01

    Full Text Available Nueve híbridos de sorgo (Sorghum bicolor L. Moench se analizaron para determinar la relación de suscaracterísticas físicas [materia seca (MS, peso de mil granos (PMG, tamaño de partícula (TP, densidad relativa(DR, superficie de área (SA, partículas por gramo (PPG, endospermo duro (END-DU, endospermo blando (ENDBL];y químicas [nitrógeno total (NT, fibra detergente ácido (FDA, fibra detergente neutro (FDN, contenidode almidón (ALM, almidón soluble (AlmS, almidón insoluble (AlmNS. La digestión ruminal esperada (DRUMse estimó con las fracciones de AlmS y AlmNS in vitro. El promedio de PMG, TP, DR, SA, PPG y END-DU fuede 24.61 g, 3.17 mm, 1.30 g/cm3, 17.44 cm2/g, 30.33 y 46.68 %, respectivamente El promedio (% de MS, PC,FDN, FDA, ALM, AlmS y AlmNS fue de 92.47, 8.19, 19.17 y 8.30, 69.58, 6.00 y 47.74 respectivamente. Laconcentración de taninos fue baja (0.05 entre las variables físicas o químicas con el contenido total de almidón en el grano;sin embargo las variables densidad relativa y superficie de área, permiten incrementar el poder de predicciónde la digestibilidad ruminal del almidón (DRUM,%= 74.058 - 0.108END-DU + 0.027SA – 5.887DR, R2= 0.77,P<0.05. De acuerdo a los resultados obtenidos, las variedades estudiadas son de dureza intermedia, libres detaninos y con un potencial de digestibilidad ruminal del almidón del 66 %.

  8. Experimental measurement of radiological penumbra associated with intermediate energy x-rays (1 MV) and small radiosurgery field sizes

    International Nuclear Information System (INIS)

    Keller, Brian M.; Beachey, David J.; Pignol, Jean-Philippe

    2007-01-01

    Stereotactic radiosurgery is used to treat intracranial lesions with a high degree of accuracy. At the present time, x-ray energies at or above Co-60 gamma rays are used. Previous Monte Carlo simulations have demonstrated that intermediate energy x-ray photons or IEPs (defined to be photons in the energy range of 0.2-1.2 MeV), combined with small field sizes, produce a reduced radiological penumbra leading to a sharper dose gradient, improved dose homogeneity and sparing of critical anatomy adjacent to the target volume. This hypothesis is based on the fact that, for small x-ray fields, a dose outside the treatment volume is dictated mainly by the range of electrons set into motion by x-ray photons. The purpose of this work is: (1) to produce intermediate energy x rays using a detuned medical linear accelerator (2) to characterize the energy of this beam (3) to measure the radiological penumbra for IEPs and small fields to compare with that produced by 6 MV x rays or Co-60, and (4) to compare these experimental measurements with Monte Carlo computer simulations. The maximum photon energy of our IEP x-ray spectrum was measured to be 1.2 MeV. Gafchromic EBT films (ISP Technologies, Wayne, NJ) were irradiated and read using a novel digital microscopy imaging system with high spatial resolution. Under identical irradiation conditions the measured radiological penumbra widths (80%-20% distance), for field sizes ranging from 0.3x0.3 to 4.0x4.0 cm 2 , varied from 0.3-0.77 mm (1.2 MV) and from 1.1-2.1 mm (6 MV). Even more dramatic were the differences found when comparing the 90%-10% or the 95%-5% widths, which are in fact more significant in radiotherapy. Monte Carlo simulations agreed well with the experimental findings. The reduction in radiological penumbra could be substantial for specific clinical situations such as in the treatment of an ocular melanoma abutting the macula or for the treatment of functional disorders such as trigeminal neuralgia (a nonlethal

  9. Ultracompact/ultralow power electron cyclotron resonance ion source for multipurpose applications

    International Nuclear Information System (INIS)

    Sortais, P.; Lamy, T.; Medard, J.; Angot, J.; Latrasse, L.; Thuillier, T.

    2010-01-01

    In order to drastically reduce the power consumption of a microwave ion source, we have studied some specific discharge cavity geometries in order to reduce the operating point below 1 W of microwave power (at 2.45 GHz). We show that it is possible to drive an electron cyclotron resonance ion source with a transmitter technology similar to those used for cellular phones. By the reduction in the size and of the required microwave power, we have developed a new type of ultralow cost ion sources. This microwave discharge system (called COMIC, for COmpact MIcrowave and Coaxial) can be used as a source of light, plasma or ions. We will show geometries of conductive cavities where it is possible, in a 20 mm diameter chamber, to reduce the ignition of the plasma below 100 mW and define typical operating points around 5 W. Inside a simple vacuum chamber it is easy to place the source and its extraction system anywhere and fully under vacuum. In that case, current densities from 0.1 to 10 mA/cm 2 (Ar, extraction 4 mm, 1 mAe, 20 kV) have been observed. Preliminary measurements and calculations show the possibility, with a two electrodes system, to extract beams within a low emittance. The first application for these ion sources is the ion injection for charge breeding, surface analyzing system and surface treatment. For this purpose, a very small extraction hole is used (typically 3/10 mm for a 3 μA extracted current with 2 W of HF power). Mass spectrum and emittance measurements will be presented. In these conditions, values down to 1 π mm mrad at 15 kV (1σ) are observed, thus very close to the ones currently observed for a surface ionization source. A major interest of this approach is the possibility to connect together several COMIC devices. We will introduce some new on-going developments such as sources for high voltage implantation platforms, fully quartz radioactive ion source at ISOLDE or large plasma generators for plasma immersion, broad or ribbon beams

  10. Analisis Elektron Beam Profile Constancy pada Pesawat Linac

    Directory of Open Access Journals (Sweden)

    Edi Guritna

    2018-02-01

    Full Text Available Radioterapi adalah pengobatan penyakit terutama tumor atau kanker ganas dengan menggunakan radiasi elektromagnetik (Sinar-X dan Gamma dan radiasi partikel (elektron, proton, dan neutron. Salah satu alat radioterapi modern yang digunakan dalam pengobatan penyakit kanker adalah linear accelerator (linac. Alat radioterapi ini menghasilkan elektron dan sinar-X (foton yang dibangkitkan oleh generator dan mempunyai energi yang bervariasi. Dalam penelitian profil dosis, digunakan pesawat liner accelerator (linac Siemens Primus berkas elektron 5 MeV dengan luas lapangan radiasi berkisar dari 5×5 cm2 sampai 25×25 cm2. Pengukuran profil dosis dilakukan dengan menggunakan water phantom,  detektor farmer chamber dan condenser chamber yang dilengkapi dengan  computer control units (CCU serta dilakukan untuk arah crossline dan inline pada kedalaman Dmax dan kedalaman tertentu. Penelitian ini bertujuan untuk menganalisis profil berkas sinar elektron energi 5 MeV pada kedalaman tertentu dan Dmax dengan variasi luas lapangan 5×5 cm2, 10×10 cm2, 15×15 cm2, 20×20 cm2, 25×25 cm2. Hasil analisis profil dosis pada berkas elektron 5 MeV menunjukkan bahwa lapangan 5×5 cm2 memiliki nilai flatness yang cukup besar sehingga dalam kalibrasi maupun terapi radiasi perlu diperhatikan penggunaan  luas lapangan tersebut. Dalam penelitian ini juga didapatkan bahwa nilai flatness paling ideal (nilai flatness rendah terjadi pada lapangan 15×15 cm2. Sehingga ada luas lapangan lain yang bisa digunakan untuk treatment maupun kalibrasi selain 10×10 cm2 yaitu 15×15 cm2 yang memiliki nilai flatness rendah.

  11. Radiation damage measurements in room temperature semiconductor radiation detectors

    International Nuclear Information System (INIS)

    Franks, L.A.; Olsen, R.W.; James, R.B.; Brunett, B.A.; Walsh, D.S.; Doyle, B.L.; Vizkelethy, G.; Trombka, J.I.

    1998-01-01

    The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI 2 ) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10 10 p/cm 2 and significant bulk leakage after 10 12 p/cm 2 . CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 x 10 9 p/cm 2 in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum of neutrons after fluences up to 10 10 n/cm 2 , although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 x 10 10 α/cm 2 produced a near linear decrease in peak position with fluence and increases in FWHM beginning at about 7.5 x 10 9 α/cm 2 . CT detectors show resolution losses after fluences of 3 x 10 9 p/cm 2 at 33 MeV for chlorine-doped detectors. Indium doped material may be more resistant. Neutron exposures (8 MeV) caused resolution losses after fluences of 2 x 10 10 n/cm 2 . Mercuric iodide has been studied with intermediate energy protons (10 to 33 MeV) at fluences up to 10 12 p/cm 2 and with 1.5 GeV protons at fluences up to 1.2 x 10 8 p/cm 2 . Neutron exposures at 8 MeV have been reported at fluences up to 10 15 n/cm 2 . No radiation damage was reported under these irradiation conditions

  12. Combining science and practice in the Danish DK-SOFC program

    DEFF Research Database (Denmark)

    Knudsen, P.; Bagger, C.; Mogensen, Mogens Bjerg

    1994-01-01

    A three-year solid oxide fuel cells (SOFC) development program completed in 1992 has produced 10 cm2 cells with area-specific resistances in the range 0.25 to 0.40 OMEGA cm2 at 1000-degrees-C. Cathode and interconnect materials were produced in the program. Sintering of electrodes, electrolyte...

  13. Comparison of additive amount used in spin-coated and roll-coated organic solar cells

    DEFF Research Database (Denmark)

    Cheng, Pei; Lin, Yuze; Zawacka, Natalia Klaudia

    2014-01-01

    All-polymer and polymer/fullerene inverted solar cells were fabricated by spin-coating and roll-coating processes. The spin-coated small-area (0.04 cm(2)) devices were fabricated on indium tin oxide (ITO) coated glass substrates in nitrogen. The roll-coated large-area (1.0 cm(2)) devices were...

  14. Self-Moving Catalytic Nanomotors

    Science.gov (United States)

    2013-12-11

    which anodic and cathodic reactions are catalyzed at separate locations on a segmented nanorod (or patterned micro-gear) (Figure 1). In this case the...concentration (green triangle). (The Cu-Pt nanorods 3 were synthesized by electrodepositing copper at -3 mA/cm2 for 10 min, and then platinum at -1 mA/cm2

  15. Highly Conformal Ni Micromesh as a Current Collecting Front Electrode for Reduced Cost Si Solar Cell

    DEFF Research Database (Denmark)

    Gupta, Nikita; Rao, K. D. M.; Gupta, Ritu

    2017-01-01

    deposition of Ni wire network on corrugated solar cell, a short circuit current of 33.28 mA/cm2 was obtained in comparison to 20.53 mA/cm2 without the network electrode. On comparing the efficiency with the conventional cells with screen printed electrodes, a 20% increment in efficiency has been observed...

  16. Determination of experimental K-shell fluorescence yield for ...

    Indian Academy of Sciences (India)

    X-ray; fluorescence yield; cross-section and chemical effects; potassium; cal- ... The X-ray production cross-section in Ti, V, Cr, Mn, Fe, Co, Ni and Cu .... where µinc (cm2 g−1) and µemt (cm2 g−1) are the mass attenuation coefficients at the.

  17. Single-grain Silicon Technology for Large Area X-ray Imaging

    NARCIS (Netherlands)

    Arslan, A.

    2015-01-01

    Digital flat panel X-ray imagers are currently using a-Si and poly-Si thin-film-transistors (TFTs). a-Si TFT permits the use of large area substrates, however, due to the amorphous nature, the carrier mobility is very low (<1 cm2/Vs). Poly-Si TFT improves the mobility (~150 cm2/Vs) but due to random

  18. Preparation of calcium-separated isotope targets using small samples

    International Nuclear Information System (INIS)

    Thomas, G.E.

    1975-01-01

    Targets are routinely evaporated using a few milligram quantities of separated isotopes of calcium with reducing agents. The source to target distance is 3.0 cm with the substrate, if necessary, as thin as 15 μg/cm 2 carbon or 100 μg/cm 2 of gold. A tantalum closed boat, heat shield, and special collimator system are used

  19. Real-time thermal neutron radiographic detection systems

    International Nuclear Information System (INIS)

    Berger, H.; Bracher, D.A.

    1976-01-01

    Systems for real-time detection of thermal neutron images are reviewed. Characteristics of one system are presented; the data include contrast, resolution and speed of response over the thermal neutron intensity range 2.5 10 3 n/cm 2 -sec to 10 7 n/cm 2 -sec

  20. A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride

    NARCIS (Netherlands)

    Zomer, P. J.; Dash, S. P.; Tombros, N.; van Wees, B. J.

    2011-01-01

    We present electronic transport measurements of single and bilayer graphene on commercially available hexagonal boron nitride. We extract mobilities as high as 125 000 cm(2) V-1 s(-1) at room temperature and 275 000 cm(2) V-1 s(-1) at 4.2 K. The excellent quality is supported by the early

  1. Testing IFE materials on Z

    International Nuclear Information System (INIS)

    Tanaka, Tina J.; Rochau, Greg A.; Peterson, Robert R.; Olson, Craig L.

    2005-01-01

    On a single-pulse basis, the tungsten armor for the chamber walls in a laser inertial fusion energy power plant must withstand X-ray fluences of 0.4-1.2 J/cm 2 with almost no mass loss, and preferably no surface changes. We have exposed preheated tungsten samples to 0.27 and 0.9 J/cm 2 X-ray fluence from the Z accelerator at Sandia National Laboratories to determine the single-shot X-ray damage threshold. Earlier focused ion beam analysis has shown that rolled powdered metal formed tungsten and tungsten alloys, will melt when exposed to 2.3 J/cm 2 on Z, but not at 1.3 J/cm 2 . Three forms of tungsten - single-crystal (SING), chemical-vapor-deposited (CVD), and rolled powdered metal (PWM) - were exposed to fluence levels of 0.9 J/cm 2 without any apparent melting. However, the CVD and PWM sample surfaces were rougher after exposure than the SING sample, which was not roughened. BUCKY (1D) calculations show a threshold of 0.5 J/cm 2 for melting on Z. The present experiments indicate no melting but limited surface changes occur with polycrystalline samples (PWM and CVD) at 0.9 J/cm 2 and no surface changes other than debris for samples at 0.27 J/cm 2

  2. Bacterial adherence: the role of serum and wound fluid | Yah ...

    African Journals Online (AJOL)

    The BAP were achieved by exposing the pathogens to freshly excised wounds. The adhered bacteria were then eluded and quantified using log (CFU/cm2) on Mueller Hinton Agar per cm2 of tissue. The results indicated that wound fluid and serum has a remarkable bacterial adherence potential (BAP) when exposed to ...

  3. Micro-structure Engineering of InGaN/GaN Quantum Wells for High Brightness Light Emitting Devices

    KAUST Repository

    Shen, Chao

    2013-01-01

    diameter (D) micro-LED-pillar was achieved, compared to that of a 200 μm diameter LED (20 A/cm2), both at 10 V bias voltage. In addition, an increase in sustained quantum efficiency from 70.2% to 83.7% at high injection current density (200 A/cm2

  4. Meiofauna of the Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Parulekar, A.H.

    Total meiofauna of the Andaman Sea, in the depth range 30-2150m was between 68 and 438/10cm2 (X-bar = 247.8). The biomass was within the range 3.57 and 32.8mg/10cm 2 (X-bar = 14.46). faunal components were maximum in sandy sediments which contained...

  5. Population-based reference values for bone mineral density in young men

    DEFF Research Database (Denmark)

    Høiberg, M; Nielsen, T L; Wraae, Kristian

    2007-01-01

    Population-based reference values for peak bone mass density in Danish men. BMD of total hip (1.078 +/- 0,14 g/cm2) differed significantly from values from National Health and Nutrition Examination Survey III and of total lumbar spine ((1.073 +/- 0.125 g/cm2) differed significantly from Hologic...

  6. Blistering in alloy Ti–6Al–4V from H + ion implantation

    Indian Academy of Sciences (India)

    6Al–4V, was studied, following H+ ion implantation of 150 keV and 250 keV energy to fluence of 2.6 × 1018 cm-2 and 2.5 × 1019 cm-2, respectively at ambient temperature. No detectable change was observed in surface features of either of the ...

  7. Radiobiological long-term accumulation of environmental alpha radioactivity in extracted human teeth and animal bones in Malaysia.

    Science.gov (United States)

    Almayahi, B A; Tajuddin, A A; Jaafar, M S

    2014-03-01

    In this study, the radiobiological analysis of natural alpha emitters in extracted human teeth and animal bones from Malaysia was estimated. The microdistributions of alpha particles in tooth and bone samples were measured using CR-39 alpha-particle track detectors. The lowest and highest alpha emission rates in teeth in the Kedah and Perak states were 0.0080 ± 0.0005 mBq cm(-2) and 0.061 ± 0.008 mBq cm(-2), whereas those of bones in the Perlis and Kedah states were 0.0140 ± 0.0001 mBq cm(-2) and 0.7700 ± 0.0282 mBq cm(-2), respectively. The average alpha emission rate in male teeth was 0.0209 ± 0.0008 mBq cm(-2), whereas that of female teeth was 0.0199 ± 0.0010 mBq cm(-2). The alpha emission rate in teeth is higher in smokers (0.0228 ± 0.0008 mBq cm(-2)) than in non-smokers (0.0179 ± 0.0008 mBq cm(-2)). Such difference was found statistically significant (p < 0.01). Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. REPELLENCY OF ESSENTIAL OIL OF PIPER ADUNCUM AGAINST AEDES ALBOPICTUS IN THE LABORATORY

    NARCIS (Netherlands)

    Misni, Norashiqin; Sulaiman, Sallehudin; Othman, Hidayatulfathi; Omar, Baharudin

    2009-01-01

    The repellent activity of Piper aduncum essential oil against Aedes albopictus was investigated under laboratory conditions with human volunteers. The lowest median effective dose (ED(50)) value was 1.5 mu g/cm(2) at 60 sec of exposure when compared to 90 see (2.1 mu g/cm(2)) and 120 see (1.8 mu

  9. Enhanced mobility of poly(3-hexylthiophene) transistors by spin-coating from high-boiling-point solvents

    DEFF Research Database (Denmark)

    Chang, J.F.; Sun, B.Q.; Breiby, Dag Werner

    2004-01-01

    chloroform are typically on the order of 0.01 cm(2)/(V s). Here we investigate a range of solvents with higher boiling points. We find that 1,2,4-trichlorobenzene with good solubility and a high boiling point significantly improves the field-effect mobilities up to 0.12 cm(2)/(V s) with on:off ratios of 10...

  10. Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

    DEFF Research Database (Denmark)

    Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.

    2016-01-01

    ) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density (icorr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied...

  11. Processing of C60 thin films by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    2011-01-01

    Thin films of fullerenes (C60) were deposited onto silicon using matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out from a frozen homogeneous dilute solution of C60 in anisole (0.67 wt%), and over a broad range of laser fluences, from 0.15 J/cm2 up to 3.9 J/cm2. MAPLE...

  12. Recommendation to include fragrance mix 2 and hydroxyisohexyl 3-cyclohexene carboxaldehyde (Lyral) in the European baseline patch test series

    DEFF Research Database (Denmark)

    Bruze, Magnus; Andersen, Klaus Ejner; Goossens, An

    2008-01-01

    various European centres when tested in consecutive dermatitis patients. CONCLUSIONS: From 2008, pet. preparations of fragrance mix 2 at 14% w/w (5.6 mg/cm(2)) and hydroxyisohexyl 3-cyclohexene carboxaldehyde at 5% w/w (2.0 mg/cm(2)) are recommended for inclusion in the baseline series. With the Finn...

  13. Low methanol permeable composite Nafion/silica/PWA membranes for low temperature direct methanol fuel cells

    International Nuclear Information System (INIS)

    Xu Weilin; Lu Tianhong; Liu Changpeng; Xing Wei

    2005-01-01

    Nafion/silica/phosphotungstic acid (PWA) composite membranes were studied for low temperature ( max = 70 mW/cm 2 ) than those of commercial Nafion without treatment (OCV = 0.68 V, P max = 62 mW/cm 2 ) at 80 deg. C

  14. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    circuit photocurrent (sc), open circuit voltage (oc) and fill factor (FF) were 7.017 mA/cm2, 0.690 V and 69.68%, respectively, for solvothermal route and they were 4.241 mA/cm2, 0.756 V and 66.74%, respectively, for co-precipitation method.

  15. Extending quantum efficiency roll-over threshold with compositionally graded InGaN/GaN LED

    KAUST Repository

    Mishra, Pawan; Ng, Tien Khee; Janjua, Bilal; Shen, Chao; Eid, Jessica; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2014-01-01

    We report a significant improvement in the electrical characteristic of compositionally graded InGaN/GaN multiple-quantum-well (MQWs) micro-LED. The efficiency droop in this device occurred at ∼20 times higher injection levels (∼275 A/cm2) compared to a conventional step-MQWs microLED (∼14 A/cm2).

  16. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy

    Science.gov (United States)

    Brooks, Emily K.; Tobias, Menachem E.; Yang, Shuying; Bone, Lawrence B.; Ehrensberger, Mark T.

    2015-01-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin) and outer layer resistance (Rout) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm2, Rout = 140 Ω/cm2) compared to 21 days (Rin = 3.60 e4 Ω/cm2, Rout = 287 Ω/cm2) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm2, Rout = 1060 Ω/cm2) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm2, Rout = 287 Ω/cm2). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. PMID:25715925

  17. Production of Antimicrobial Films by Incorporation of Partially Purified Lysozyme into Biodegradable Films of Crude Exopolysaccharides Obtained from Aureobasidium pullulans Fermentation

    Directory of Open Access Journals (Sweden)

    Nilay Kandemir

    2005-01-01

    Full Text Available Antimicrobial films were produced by incorporating partially purified lysozyme into films of crude exopolysaccharides (59 % pullulan obtained from Aureobasidium pullulans fermentation. After film making, the films containing lysozyme at 100, 260, 520 and 780 μg/cm2 showed 23 to 70 % of their expected enzyme activities. The highest recovery of enzyme activity (65–70 % after the film making was obtained in films prepared by incorporating lysozyme at 260 μg/cm2 (1409 U/cm2. The incorporation of disodium EDTA×2H2O and sucrose did not affect the initial lysozyme activity of the films significantly. With or without the presence of disodium EDTA×2H2O at 52 or 520 μg/cm2, lysozyme activity showed sufficient stability in the films during 21 days of cold storage. However, the presence of sucrose at 10 mg/cm2 in the films caused the destabilization of part of enzyme activity (almost 35 % at the end of storage. The combinational incorporation of lysozyme at 780 μg/cm2 (4227 U/cm2 and disodium EDTA×2H2O at 520 μg/cm2 gave antimicrobial films effective on Escherichia coli. However, in the studied lysozyme concentration range the films did not show any antimicrobial activity against Lactobacillus plantarum. This study clearly showed that the partially purified lysozyme and crude exopolysaccharides from Aureobasidium pullulans may be used to obtain antimicrobial films to increase the safety of foods.

  18. Parallel plate detectors

    International Nuclear Information System (INIS)

    Gardes, D.; Volkov, P.

    1981-01-01

    A 5x3cm 2 (timing only) and a 15x5cm 2 (timing and position) parallel plate avalanche counters (PPAC) are considered. The theory of operation and timing resolution is given. The measurement set-up and the curves of experimental results illustrate the possibilities of the two counters [fr

  19. 40 CFR 799.4360 - Tributyl phosphate.

    Science.gov (United States)

    2010-07-01

    ... substance shall be applied to the intact clipped skin (approximately 2 cm2 for rats, 40 cm2 for mini-pigs... cells from the test solution shall be done using an ultrafiltration (e.g., 0.45 micrometer pore size...

  20. Extending quantum efficiency roll-over threshold with compositionally graded InGaN/GaN LED

    KAUST Repository

    Mishra, Pawan

    2014-12-01

    We report a significant improvement in the electrical characteristic of compositionally graded InGaN/GaN multiple-quantum-well (MQWs) micro-LED. The efficiency droop in this device occurred at ∼20 times higher injection levels (∼275 A/cm2) compared to a conventional step-MQWs microLED (∼14 A/cm2).

  1. Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

    KAUST Repository

    Mei, Jianguo; Kim, Do Hwan; Ayzner, Alexander L.; Toney, Michael F.; Bao, Zhenan

    2011-01-01

    We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1

  2. Archetypal sandwich-structured CuO for high performance non-enzymatic sensing of glucose

    Science.gov (United States)

    Meher, Sumanta Kumar; Rao, G. Ranga

    2013-02-01

    In the quest to enhance the selectivity and sensitivity of novel structured metal oxides for electrochemical non-enzymatic sensing of glucose, we report here a green synthesis of unique sandwich-structured CuO on a large scale under microwave mediated homogeneous precipitation conditions. The physicochemical studies carried out by XRD and BET methods show that the monoclinic CuO formed via thermal decomposition of Cu2(OH)2CO3 possesses monomodal channel-type pores with largely improved surface area (~43 m2 g-1) and pore volume (0.163 cm3 g-1). The fascinating surface morphology and pore structure of CuO is formulated due to homogeneous crystallization and microwave induced self assembly during synthesis. The cyclic voltammetry and chronoamperometry studies show diffusion controlled glucose oxidation at ~0.6 V (vs. Ag/AgCl) with extremely high sensitivity of 5342.8 μA mM-1 cm-2 and respective detection limit and response time of ~1 μM and ~0.7 s, under a wide dynamic concentration range of glucose. The chronoamperometry measurements demonstrate that the sensitivity of CuO to glucose is unaffected by the absence of dissolved oxygen and presence of poisoning chloride ions in the reaction medium, which essentially implies high poison resistance activity of the sandwich-structured CuO. The sandwich-structured CuO also shows insignificant interference/significant selectivity to glucose, even in the presence of high concentrations of other sugars as well as reducing species. In addition, the sandwich-structured CuO shows excellent reproducibility (relative standard deviation of ~2.4% over ten identically fabricated electrodes) and outstanding long term stability (only ~1.3% loss in sensitivity over a period of one month) during non-enzymatic electrochemical sensing of glucose. The unique microstructure and suitable channel-type pore architecture provide structural stability and maximum accessible electroactive surface for unimpeded mobility of glucose as well as the

  3. Curcumin Enhances Bortezomib Treatment of Myeloma by Inhibiting ...

    African Journals Online (AJOL)

    Purpose: To investigate whether curcumin augments bortezomib-induced apoptosis in myeloma cells (MM1.R line), and to explore the molecular mechanism with regard to heat shock protein 90 (HSP90) expression. Methods: MTT cell viability assay was used to assess growth inhibition of MM1.R cells at different ...

  4. Measurement of off-axis and peripheral skin dose using radiochromic film

    International Nuclear Information System (INIS)

    Butson, Martin J.; Yu, P.K.N.; Metcalfe, P.E.

    1998-01-01

    A radiotherapy skin dose profile can be obtained with radiochromic film. The central axis skin dose relative to D max for a 10x10cm 2 field size was found to be 22%, 17% and 15.5% for 6 MV, 10 MV and 18 MV photon beams. Peripheral dose increased with increasing field size. At 10 MV the skin dose 2 cm outside the geometric field edge was measured as 6%, 10% and 17% for 10x10cm 2 , 20x20cm 2 and 30x30cm 2 field sizes respectively. Off-axis skin dose decreased as distance increased from central axis for fields with Perspex block trays. For a 20x20cm 2 field, an approximately 5-8% drop in percentage skin dose was observed from central axis to the beam edge. (author)

  5. Amorphization of ceramics by ion beams

    International Nuclear Information System (INIS)

    McHargue, C.J.; Farlow, G.C.; White, C.W.; Williams, J.M.; Appleton, B.R.; Naramoto, H.

    1984-01-01

    The influence of the implantation parameters fluence, substrate temperature, and chemical species on the formation of amorphous phases in Al 2 O 3 and α-SiC was studied. At 300 0 K, fluences in excess of 10 17 ions.cm -2 were generally required to amorphize Al 2 O 3 ; however, implantation of zirconium formed the amorphous phase at a fluence of 4 x 10 16 Zr.cm -2 . At 77 0 K, the threshold fluence was lowered to about 2 x 10 15 Cr.cm -2 . Single crystals of α-SiC were amorphized at 300 0 K by a fluence of 2 x 10 14 Cr.cm -2 or 1 x 10 15 N.cm -2 . Implantation at 1023 0 K did not produce the amorphous phase in SiC. The micro-indentation hardness of the amorphous material was about 60% of that of the crystalline counterpart

  6. TPR Measurement for Co-60 Teletherapy Unit

    International Nuclear Information System (INIS)

    Heru-Prasetio; Nasukha

    2001-01-01

    Dosage delivery to a certain tissue within radiation field should be carefully determined. Although direct measurement is possible to accomplish, calculation is still required. The usage of TPR table in calculation will give benefit in dosage delivery to patients. Before standard TPR table is used, TPR value of Co-60 teletherapy unit should be determined and compared with standard TPR table. Comparison of measured TPR and standard TPR table which is provided by BJR, showed no significant differences for 8 x 8 cm 2 , 10 x 10 cm 2 , 15 x 15 cm 2 , 20 x 20 cm 2 , and 25 x 25 cm 2 square fields, in depth of 1 cm up to 6 cm. All result of new TPR is compared to TPR table in BJR and found differences of less than 1 %. These results is satisfactory and TPR from BJR table can be used as a basis in dose calculation. (author)

  7. Implementation of an Euler/Navier-Stokes finite element algorithm on the Connection Machine

    International Nuclear Information System (INIS)

    Shapiro, R.A.

    1991-01-01

    Massively parallel computers such as the Connection Machine (CM-2) have the potential to reduce significantly the computational cost for large problems of interest to the aerospace community. This paper examines the applicability of the CM-2 to an explicit, time-marching finite element solution method for the Euler and Navier-Stokes equations. The CM-2 architecture and the CM FORTRAN language are introduced. The paper points out some of the pitfalls involved in putting this code on the CM-2, with emphasis on interprocessor communications issues. The use of the FastGraph communication compiler and grid renumbering to reduce communication costs is discussed. Performance comparisons which indicate the approximate equivalence of a uniprocessor Cray and 1/8 of a CM-2 (8192 processors) for some typical problems are presented. 8 refs

  8. Performance studies under high irradiation and ageing properties of resistive bulk Micromegas chambers at the new CERN Gamma Irradiation Facility

    International Nuclear Information System (INIS)

    Sidiropoulou, O.; Gonzalez, B. Alvarez; Bianco, M.; Farina, E.M.; Iengo, P.; Longo, L.; Pfeiffer, D.; Wotschack, J.

    2017-01-01

    Resistive bulk Micromegas chambers, produced at CERN, have been installed at the new CERN Gamma Irradiation Facility (GIF++) in order to study the effects of ageing and to evaluate the detector behaviour under high irradiation. The chambers have an active area of 10×10 cm 2 , strip pitch of 400 μm and an amplification gap of 128 μm. We present the detector performance as a function of the background rate of up to 20 MHz/cm 2 . - Highlights: • Small-size resistive bulk Micromegas detectors have been exposed to the new GIF++. • 9 months irradiation to γ up to 20 Mhz/cm 2 . 0.09 C/cm 2 collected integrated charge. • Νo degradation of the detector performance was observed. • Muon tracks successfully reconstructed up to 68 kHz/cm 2 gamma background. • Higher background rates will be studied in the coming months.

  9. A serosa-searing apparatus for producing gastric ulcer in rats.

    Science.gov (United States)

    Kagoshima, M; Suzuki, T; Katagiri, S; Shimada, H

    1994-12-01

    Chronic ulcer models produced by serosa-searing method are very similar histologically to the ulcer healing process occurring in humans. In an effort to produce a serosa-searing chronic ulcer model in rats, we devised a new balance-type apparatus. This searing apparatus is capable of changing adequately both temperature and duration of time. Furthermore, the pressure which serves to bring the searing iron tip into contact with the stomach serosa surface can also be precisely changed. Optimal conditions for reproducing the serosa-searing ulcer model were at 65 degrees C and in 5 sec. Moreover, in order to evaluate the effects of pressure, various pressure levels (A: 5 g, 17.68 g/cm2; B: 10 g, 35.37 g/cm2; C: 15 g, 53.05 g/cm2; D: 20 g, 70.74 g/cm2; E: 25 g, 88.42 g/cm2; F: 30 g, 106.10 g/cm2; G: 35 g, 123.79 g/cm2 (+/- 1 g, 0.149 g/cm2)) of 5-sec duration at 65 +/- 0.1 degrees C were used. Macroscopically, gastric mucosal lesions were most clearly observed in a pressure-related manner 7 days after the procedure. Histologically, definite deep ulcerations (UI-III or UI-IV) were observed at pressure level C (15 g, 53.05 g/cm2) or more. The highest incidence (87%) of histological gastric ulcers (UI-IV) was observed in pressure level E (25 g, 88.42 g/cm2). The healing process was observed at 40 to 60 days postoperatively. At 100 days after the procedure, recurrences were observed both macroscopically and histologically. In conclusion, this new apparatus is very useful for reproducing a chronic ulcer model for observing the healing and recurrence process.

  10. Thermal Harvesting Potential of the Human Body

    Science.gov (United States)

    Thielen, Moritz; Kara, Gökhan; Unkovic, Ivana; Majoe, Dennis; Hierold, Christofer

    2018-02-01

    Thermoelectric energy harvesting of human body heat might supplement or even replace conventional energy storage in wearable devices for healthcare and the Internet of Humans. Although a number of thermal harvesters are presented in the literature, no conclusive data can be found on the amount of available thermal energy provided by different individuals and activities. We here present the results of an observational study with 56 test subjects of different ages (children, adults and elderly) and gender, performing predefined activities (sitting, walking) in varying environments (indoor, outdoor). Our study showed a statistical difference of thermal potential and skin properties between age groups, but not between genders. On average, stationary elderly test subjects produced ˜ 32% less heat flux compared to minors (mean: children = 13.9 mW/cm2, adults = 11.4 mW/cm2, elderly = 9.4 mW/cm2). This potentially correlates with an increase in thermal skin resistance with age (children = 494 cm2 K/W, adults = 549 cm2 K/W, elderly = 835 cm2 K/W). The mean harvested power varied from 12.2 μW/cm2 (elderly) to 26.2 μW/cm2 (children) for stationary, and from 20.2 μW/cm2 (elderly) to 69.5 μW/cm2 (children) for active subjects inside of a building. The findings of this study can be used to better anticipate the available energy for different usage scenarios of thermal harvesters and optimize wearable systems accordingly.

  11. [Simultaneous determination of multiple elements in airborne particulate samples by X-ray fluorescence spectrometry].

    Science.gov (United States)

    Takada, T; Hitosugi, M; Kadowaki, T; Kudo, M

    1983-07-01

    An energy dispersive X-ray fluorescence spectrometer (EDX) has been applied to determine multielements in the workplace air. The standards for X-ray fluorescence analysis were prepared by the chelate precipitation method on polyvinyl chloride (PVC) membrane filter. And, the specimens were prepared to deposit various metal compounds of different chemical forms by the suspension method on PVC membrane filter, and they were determined with EDX and atomic absorption spectrometer (AAS). The results obtained were as follows. Though there is a difference by each element, an amount less than 3 microgram/cm2 per unit area makes it possible to undergo multielement analysis, that is, is has no influence on fine particle effect (particle size; under 5 microns). Then, effects of the X-ray intensity by different chemical forms are negligible. At the presence the neighboring element and other elements this technique showed greater precision by carrying out on corrective treatment, etc. The coefficient of variation of this technique was in the range of 2.5-6.5% at DDTC-Cu of 0.5-5.0 micrograms/cm2, with the limit of detection for As : 0.002 microgram/cm2, Zn : 0.003 microgram/cm2, Pb : 0.003 microgram/cm2, Cu : 0.004 microgram/cm2, Ni : 0.003 microgram/cm2, Fe : 0.005 microgram/cm2, Mn : 0.008 microgram/cm2, Cr : 0.013 microgram/cm2, respectively. Aerosols collected at the workplace were analyzed with EDX and AAS, and the obtained results showed good agreement with such regression line as y = 1.04 chi + 0.04, the coefficient of correlation being r = 0.995. From these results, this technique was found to be a very excellent method for monitoring of multielements in the workplace air.

  12. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - an in vitro study.

    Science.gov (United States)

    Raghunath Reddy, M H; Subba Reddy, V V; Basappa, N

    2010-01-01

    An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ). Negligible difference (0.59 kg/cm 2 ) of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 ) and glass ionomer cements (20.69 kg/cm 2 ). Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

  13. 808-nm laser therapy with a flat-top handpiece photobiomodulates mitochondria activities of Paramecium primaurelia (Protozoa).

    Science.gov (United States)

    Amaroli, Andrea; Ravera, Silvia; Parker, Steven; Panfoli, Isabella; Benedicenti, Alberico; Benedicenti, Stefano

    2016-05-01

    Photobiomodulation is proposed as a non-linear process, and only low-level laser therapy (LLLT) is assumed to stimulate exposed cells, whereas high powered laser and fluences can cause negative effects, exhausting the cell's energy reserve as a consequence of excessive photon-based stimulation. In our work, we investigated and compared the effects of 808-nm diode laser (CW) with a new flat-top handpiece. To this purpose, we tested the photobiomodulation effects of 1 and 3 J/cm(2) fluence, both generated by 100 mW or 1 W of laser power and of 64 J/cm(2) of fluence generated by 100 mW, 1 W, 1.5 W or 2 W, as expressed through oxygen consumption and ATP synthesis of Paramecium. Data collected indicates the incremental consumption of oxygen through irradiation with 3 J/cm(2)-100 mW or 64 J/cm(2)-1 W correlates with an increase in Paramecium ATP synthesis. The Paramecium respiration was inhibited by fluences 64 J/cm(2)-100 mW or 64 J/cm(2)-2 W and was followed by a decrease in the endogenous ATP concentration. The 1 J/cm(2)-100 mW or 1 W and 3 J/cm(2)-1 W did not affect mitochondrial activity. The results show that the fluence of 64 J/cm(2)-1 W more than the 3 J/cm(2)-100 mW causes greater efficiency in Paramecium mitochondria respiratory chain activity. Our results suggest that thanks to flat-top handpiece we used, high fluences by high-powered laser have to be reconsidered as an effective and non-invasive therapy. Possible associated benefits of deeper tissue penetration would increase treatment effectiveness and reduced irradiation time.

  14. Thermal Harvesting Potential of the Human Body

    Science.gov (United States)

    Thielen, Moritz; Kara, Gökhan; Unkovic, Ivana; Majoe, Dennis; Hierold, Christofer

    2018-06-01

    Thermoelectric energy harvesting of human body heat might supplement or even replace conventional energy storage in wearable devices for healthcare and the Internet of Humans. Although a number of thermal harvesters are presented in the literature, no conclusive data can be found on the amount of available thermal energy provided by different individuals and activities. We here present the results of an observational study with 56 test subjects of different ages (children, adults and elderly) and gender, performing predefined activities (sitting, walking) in varying environments (indoor, outdoor). Our study showed a statistical difference of thermal potential and skin properties between age groups, but not between genders. On average, stationary elderly test subjects produced ˜ 32% less heat flux compared to minors (mean: children = 13.9 mW/cm2, adults = 11.4 mW/cm2, elderly = 9.4 mW/cm2). This potentially correlates with an increase in thermal skin resistance with age (children = 494 cm2 K/W, adults = 549 cm2 K/W, elderly = 835 cm2 K/W). The mean harvested power varied from 12.2 μW/cm2 (elderly) to 26.2 μW/cm2 (children) for stationary, and from 20.2 μW/cm2 (elderly) to 69.5 μW/cm2 (children) for active subjects inside of a building. The findings of this study can be used to better anticipate the available energy for different usage scenarios of thermal harvesters and optimize wearable systems accordingly.

  15. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study

    Directory of Open Access Journals (Sweden)

    Raghunath Reddy M

    2010-01-01

    Full Text Available An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 . Negligible difference (0.59 kg/cm 2 of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 and glass ionomer cements (20.69 kg/cm 2 . Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

  16. Echo Particle Image Velocimetry for Estimation of Carotid Artery Wall Shear Stress: Repeatability, Reproducibility and Comparison with Phase-Contrast Magnetic Resonance Imaging.

    Science.gov (United States)

    Gurung, Arati; Gates, Phillip E; Mazzaro, Luciano; Fulford, Jonathan; Zhang, Fuxing; Barker, Alex J; Hertzberg, Jean; Aizawa, Kunihiko; Strain, William D; Elyas, Salim; Shore, Angela C; Shandas, Robin

    2017-08-01

    Measurement of hemodynamic wall shear stress (WSS) is important in investigating the role of WSS in the initiation and progression of atherosclerosis. Echo particle image velocimetry (echo PIV) is a novel ultrasound-based technique for measuring WSS in vivo that has previously been validated in vitro using the standard optical PIV technique. We evaluated the repeatability and reproducibility of echo PIV for measuring WSS in the human common carotid artery. We measured WSS in 28 healthy participants (18 males and 10 females, mean age: 56 ± 12 y). Echo PIV was highly repeatable, with an intra-observer variability of 1.0 ± 0.1 dyn/cm 2 for peak systolic (maximum), 0.9 dyn/cm 2 for mean and 0.5 dyn/cm 2 for end-diastolic (minimum) WSS measurements. Likewise, echo PIV was reproducible, with a low inter-observer variability (max: 2.0 ± 0.2 dyn/cm 2 , mean: 1.3 ± 0.1 dyn/cm 2 , end-diastolic: 0.7 dyn/cm 2 ) and more variable inter-scan (test-retest) variability (max: 7.1 ± 2.3 dyn/cm 2 , mean: 2.9 ± 0.4 dyn/cm 2 , min: 1.5 ± 0.1 dyn/cm 2 ). We compared echo PIV with the reference method, phase-contrast magnetic resonance imaging (PC-MRI); echo PIV-based WSS measurements agreed qualitatively with PC-MRI measurements (r = 0.89, p PIV vs. PC-MRI): WSS at peak systole: 21 ± 7.0 dyn/cm 2 vs. 15 ± 5.0 dyn/cm 2 ; time-averaged WSS: 8.9 ± 3.0 dyn/cm 2 vs. 7.1 ± 3.0 dyn/cm 2 (p  0.05). For the first time, we report that echo PIV can measure WSS with good repeatability and reproducibility in adult humans with a broad age range. Echo PIV is feasible in humans and offers an easy-to-use, ultrasound-based, quantitative technique for measuring WSS in vivo in humans with good repeatability and reproducibility. Copyright © 2017. Published by Elsevier Inc.

  17. The fifth decade of ISOLDE: HIE-ISOLDE. (2/2)

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    The On-Line Isotope Mass Separator ISOLDE is a facility dedicated to the production of a large variety of radioactive ion beams for a great number of different experiments, e.g. in the field of nuclear and atomic physics, solid-state physics, life sciences and material science. At ISOLDE, radioactive nuclides are produced in thick high-temperature targets via spallation, fission or fragmentation reactions. The targets are placed in the external proton beam of the PSB, which has an energy of 1.0 or 1.4 GeV and an intensity of about 2 microA. The target and ion-source together represent a small chemical factory for converting the nuclear reaction products into a radioactive ion beam. An electric field accelerates the ions, which are mass separated and steered to the experiments. Until now more than 600 isotopes of more than 60 elements (Z=2 to 88) have been produced with half-lives down to milliseconds and intensities up to 1011 ions per second. Through the advent of post-accelerated beams with the REX-ISOLDE c...

  18. Nafion/lead nitroprusside nanoparticles modified carbon ceramic electrode as a novel amperometric sensor for L-cysteine.

    Science.gov (United States)

    Razmi, H; Heidari, H

    2009-05-01

    This work describes the electrochemical and electrocatalytic properties of carbon ceramic electrode (CCE) modified with lead nitroprusside (PbNP) nanoparticles as a new electrocatalyst material. The structure of deposited film on the CCE was characterized by energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The cyclic voltammogram (CV) of the PbNP modified CCE showed two well-defined redox couples due to [Fe(CN)5NO](3-)/[Fe(CN)5NO](2-) and Pb(IV)/Pb(II) redox reactions. The modified electrode showed electrocatalytic activity toward the oxidation of L-cysteine and was used as an amperometric sensor. Also, to reduce the fouling effect of L-cysteine and its oxidation products on the modified electrode, a thin film of Nafion was coated on the electrode surface. The sensor response was linearly changed with L-cysteine concentration in the range of 1 x 10(-6) to 6.72 x 10(-5)mol L(-1) with a detection limit (signal/noise ratio [S/N]=3) of 0.46 microM. The sensor sensitivity was 0.17 microA (microM)(-1), and some important advantages such as simple preparation, fast response, good stability, interference-free signals, antifouling properties, and reproducibility of the sensor for amperometric determination of L-cysteine were achieved.

  19. Jefferson Lab, a status report

    International Nuclear Information System (INIS)

    Dunham, B.M.

    1996-01-01

    Thomas Jefferson National Accelerator Facility (Jefferson Lab; formerly known as CEBAF), operates a 4 GeV, 200 microA continuous wave (CW) electron accelerator that re-circulates the beam five times through two superconducting 400 MeV linacs. Electrons can be extracted from any of the five recirculation passes and beam can be simultaneously delivered to the three experimental halls. As the commissioning stage nears completion, the accelerator is becoming a fully operational machine. Experiments in Hall C have been underway since November 1995 with beam powers of over 300 kW at various energies. Hall A has received beam for spectrometer commissioning, while Hall B is expected to receive its first beam in the fall of 1996. Accelerator availability of greater than 70% during physics runs and excellent beam quality have contributed to making Jefferson Lab a world class laboratory for accelerator-based electromagnetic nuclear physics. With the high performance of the superconducting RF cavities, machine upgrades to 6 GeV, and eventually 8 to 10 GeV are now in the planning stages. Operational and commissioning details concerning all aspects of the machine will be discussed

  20. High efficiency charge recuperation for electron beams of MeV energies

    International Nuclear Information System (INIS)

    MacLachlan, J.A.

    1996-05-01

    Electron cooling of ion beams with energies of some GeV per nucleon requires high-quality electron beams of MeV energies and currents as high as several amperes. The enormous beam power dictates that the beam current be returned to the high voltage terminal which provides the accelerating potential. The beam is returned to a carefully designed collector within the terminal and biased a few kV positive with respect to it. Thus the load on the HV supply is only the accelerating potential times the sum of the beam current loss and the current used to maintain a graded potential on the accelerating structure. If one employs an electrostatic HV supply like a Van de Graaff with maximum charging current of a few hundred microA, the permissible fractional loss is ∼ 10 -4 . During the 15 years or so the concept of medium energy electron cooling has been evolving, the need to demonstrate the practicability of such high efficiency beam recovery has been recognized. This paper will review some experimental tests and further experiments which have been proposed. The design and status are presented for a new re-circulation experiment at 2 MV being carried out by Fermilab at National Electrostatics Corp

  1. Injector for CESAR (2 MeV electron storage ring): 2-beam, 2 MV van de Graaff generator; tank removed.

    CERN Multimedia

    CERN PhotoLab

    1968-01-01

    The van de Graaff generator in its tank. For voltage-holding, the tank was filled with pressurized extra-dry nitrogen. 2 beams emanated from 2 separate electron-guns. The left beam, for injection into the CESAR ring, was pulsed at 50 Hz, with currents of up to 1 A for 400 ns. The right beam was sent to a spectrometer line. Its pulselength was also 400 ns, but the pulse current was 12 microA, at a rate variable from 50 kHz to 1 MHz. This allowed stabilization of the top-terminal voltage to an unprecedented stability of +- 100 V, i.e. 6E-5. Although built for a nominal voltage of 2 MV, the operational voltage was limited to 1.75 MV in order to minimize voltage break-down events. CESAR was terminated at the end of 1967 and dismantled in 1968. R.Nettleton (left) and H.Burridge (right) are preparing the van de Graaff for shipment to the University of Swansea.

  2. A wireless batteryless in vivo EKG and core body temperature sensing microsystem with 60 Hz suppression technique for untethered genetically engineered mice real-time monitoring.

    Science.gov (United States)

    Chaimanonart, Nattapon; Young, Darrin J

    2009-01-01

    A wireless, batteryless, and implantable EKG and core body temperature sensing microsystem with adaptive RF powering for untethered genetically engineered mice real-time monitoring is designed, implemented, and in vivo characterized. A packaged microsystem, exhibiting a total size of 9 mm x 7 mm x 3 mm with a weight of 400 mg including a pair of stainless-steel EKG electrodes, is implanted in a mouse abdomen for real-time monitoring. A low power 2 mm x 2 mm ASIC, consisting of an EKG amplifier, a proportional-to-absolute-temperature (PTAT)-based temperature sensor, an RF power sensing circuit, an RF-DC power converter, an 8-bit ADC, digital control circuitry, and a 433 MHz FSK transmitter, is powered by an adaptively controlled external RF energy source at 4 MHz to ensure a stable 2V supply with 156microA current driving capability for the overall microsystem. An electrical model for analyzing 60 Hz interference based on 2-electrode and 3-electrode configurations is proposed and compared with in vivo evaluation results. Due to the small laboratory animal chest area, a 60 Hz suppression technique by employing input termination resistors is chosen for two-EKG-electrode implant configuration.

  3. Safety and performance of a long life lithium-thionyl chloride battery

    Science.gov (United States)

    Cieslak, W. R.; Street, H. K.

    A Li/SOCl2 'D' cell for applications requiring 10 to 15 years life at very low drain rates, typically less than 150 microA, were developed. Maximizing cell safety and reliability, while delivering very good energy density, were the goals. These goals were achieved by designing the cell to be application specific. The low-rate cell was optimized to deliver up to 16 Ah at drain rates of less than 70 mA. By virtue of its low surface area, 145 cm(sup 2), the cell demonstrated excellent safety behavior. Safety testing was performed on individual cells as well as on two-cell and four-cell batteries. Single cells did not vent when short-circuited. Benign venting in a two cell string was produced, but only when the string was partially discharged before shorting. The vent mechanism is a 300 psi rupture pressure burst disc manufactured by BS&B Safety Systems. Benign venting is defined as full opening of the 3/8 in. dia vent hole without deformation of the case. Material is expelled from the cell without flame, and the cell stack remains largely intact. Venting of the Sandia-designed low rate cell was not produced under any other abuse test conditions. The vent functions as an ultimate safety mechanism in the case of severe abuse, but resistance to venting under normal use and mild abuse conditions is key to the achievement of high reliability.

  4. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE.

    Science.gov (United States)

    Anderson, N G; Butler, A P; Scott, N J A; Cook, N J; Butzer, J S; Schleich, N; Firsching, M; Grasset, R; de Ruiter, N; Campbell, M; Butler, P H

    2010-09-01

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 microA). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct from soft tissue and bone in all six mice. Calcium, iodine and barium were displayed as separate channels on 3D colour images at contrast agents with K-edges only 4 keV apart. Multi-contrast imaging and molecular CT are potential future applications.

  5. A rich revenue from the use of radioactive beams and radioactive targets: recent highlights from the nTOF and ISOLDE facilities (1/2)

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    The On-Line Isotope Mass Separator ISOLDE is a facility dedicated to the production of a large variety of radioactive ion beams for a great number of different experiments, e.g. in the field of nuclear and atomic physics, solid-state physics, life sciences and material science. At ISOLDE, radioactive nuclides are produced in thick high-temperature targets via spallation, fission or fragmentation reactions. The targets are placed in the external proton beam of the PSB, which has an energy of 1.0 or 1.4 GeV and an intensity of about 2 microA. The target and ion-source together represent a small chemical factory for converting the nuclear reaction products into a radioactive ion beam. An electric field accelerates the ions, which are mass separated and steered to the experiments. Until now more than 600 isotopes of more than 60 elements (Z=2 to 88) have been produced with half-lives down to milliseconds and intensities up to 1011 ions per second. Through the advent of post-accelerated beams with the REX-ISOLDE c...

  6. A PET system based on 2-18FDG production with a low energy electrostatic proton accelerator and a dual headed PET scanner.

    Science.gov (United States)

    Sandell, A; Ohlsson, T; Erlandsson, K; Hellborg, R; Strand, S E

    1992-01-01

    We have developed a comparatively inexpensive PET system, based on a rotating scanner with two scintillation camera heads, and a nearby low energy electrostatic proton accelerator for production of short-lived radionuclides. Using a 6 MeV proton beam of 5 microA, and by optimization of the target geometry for the 18O(p,n)18F reaction, 750 MBq of 2-18FDG can be obtained. The PET scanner shows a spatial resolution of 6 mm (FWHM) and a sensitivity of 80 s-1kBq-1ml-1 (3 kcps/microCi/ml). Various corrections are included in the imaging process, to compensate for spatial and temporal response variations in the detector system. Both filtered backprojection and iterative reconstruction methods are employed. Clinical studies have been performed with acquisition times of 30-40 min. The system will be used for clinical experimental research with short- as well as long-lived positron emitters. Also the possibility of true 3D reconstruction is under evaluation.

  7. The Weak Charge of the Proton. A Search For Physics Beyond the Standard Model

    Energy Technology Data Exchange (ETDEWEB)

    MacEwan, Scott J. [Univ. of Manitoba, Winnipeg, MB (Canada)

    2015-05-01

    The Qweak experiment, which completed running in May of 2012 at Jefferson Laboratory, has measured the parity-violating asymmetry in elastic electron-proton scattering at four-momentum transfer Q2 =0.025 (GeV/c)2 in order to provide the first direct measurement of the proton's weak charge, QWp. The Standard Model makes firm predictions for the weak charge; deviations from the predicted value would provide strong evidence of new physics beyond the Standard Model. Using an 89% polarized electron beam at 145 microA scattering from a 34.4 cm long liquid hydrogen target, scattered electrons were detected using an array of eight fused-silica detectors placed symmetric about the beam axis. The parity-violating asymmetry was then measured by reversing the helicity of the incoming electrons and measuring the normalized difference in rate seen in the detectors. The low Q2 enables a theoretically clean measurement; the higher-order hadronic corrections are constrained using previous parity-violating electron scattering world data. The experimental method will be discussed, with recent results constituting 4% of our total data and projections of our proposed uncertainties on the full data set.

  8. A ''Winner-Take-All'' IC for determining the crystal of interaction in PET detectors

    International Nuclear Information System (INIS)

    Moses, W.W.; Beuville, E.; Ho, M.H.

    1996-01-01

    The authors present performance measurements of a Winner-Take-All (WTA) CMOS integrated circuit to be used with a pixel based PET detector module. Given n input voltages, it rapidly determines the input with the largest voltage, and outputs the encoded address of this input and a voltage proportional to this largest voltage. This is more desirable than a threshold approach for applications that require exactly one channel to be identified or when noise is a significant fraction of the input signal. A sixteen input prototype has been fabricated using two 1.2 microm processes (HP linear MOS capacitance and Orbit double-poly capacitance). ICs from both processes reliably identify (within 50 ns) the maximum channel if ΔV (the difference between the two highest channels) is >20 mV. The key element in the WTA circuit is an array of high gain nonlinear current amplifiers. There is one amplifier for each input channel, and each amplifier is composed of only two FETs. All amplifiers are supplied by a common, limited current source, so the channel with the largest input current takes all of this supply current while the other channels receive virtually none. Thus, these amplifier outputs become a set of logical bits that identify the maximum channel, which is encoded and used to select a multiplexer input. A voltage to current converter at each input channel turns this into a voltage sensitive device. This circuit uses very little power, drawing approximately 100 microA at 5 V

  9. Role of the parabrachial complex in the cardiorespiratory response evoked from hypothalamic defense area stimulation in the anesthetized rat.

    Science.gov (United States)

    Díaz-Casares, Amelia; López-González, Manuel Víctor; Peinado-Aragonés, Carlos Antonio; Lara, José Pablo; González-Barón, Salvador; Dawid-Milner, Marc Stefan

    2009-07-07

    To analyze the role of parabrachial complex (PBc) in the modulation of cardiorespiratory response evoked from the hypothalamic defense area (HDA), cardiorespiratory changes were analyzed in spontaneously breathing anesthetised rats in response to electrical stimulation of the HDA (1 ms pulses, 30-50 microA, 100 Hz for 5 s) before and after the microinjection of muscimol (50 nl, 0.25 nmol, 5 s) within the PBc. HDA stimulation evoked an inspiratory facilitatory response, consisting of an increase in respiratory rate (pHDA stimulation (pHDA stimulation. The respiratory response persisted unchanged. Finally, extracellular recording of putative neurons from these regions were obtained during HDA stimulation to confirm functional interaction between HDA and parabrachial regions. 105 pontine cells were recorded during HDA stimulation, 57 from the lPB and 48 from the mPB-KF. In mPB-KF 34/48 (71%) and in lPB 38/57 (67%) cells were influenced from HDA. The results indicate that neurons from different regions of the PBc have an important function in mediating the cardiorespiratory response evoked from the HDA. The possible mechanisms involved in these interactions are discussed.

  10. Prevention of pin tract infection in external stainless steel fixator frames using electric current in a goat model.

    Science.gov (United States)

    van der Borden, Arnout J; Maathuis, Patrick G M; Engels, Eefje; Rakhorst, Gerhard; van der Mei, Henny C; Busscher, Henk J; Sharma, Prashant Kumar

    2007-04-01

    Pin tract infections of external fixators used in orthopaedic reconstructive bone surgery are serious complications that can eventually lead to periostitis and osteomyelitis. In vitro experiments have demonstrated that bacteria adhering to stainless steel in a biofilm mode of growth detach under the influence of small electric currents, while remaining bacteria become less viable upon current application. Therefore, we have investigated whether a 100microA electric current can prevent signs of clinical infection around percutaneous pins, implanted in the tibia of goats. Three pins were inserted into the lateral right tibia of nine goats, of which one served for additional frame support. Two pins were infected with a Staphylococcus epidermidis strain of which one pin was subjected to electric current, while the other pin was used as control. Pin sites were examined daily. The wound electrical resistance decreased with worsening of the infection from a dry condition to a purulent stage. After 21 days, animals were sacrificed and the pins taken out. Infection developed in 89% of the control pin sites, whereas only 11% of the pin sites in the current group showed infection. These results show that infection of percutaneous pin sites of external fixators in reconstructive bone surgery can be prevented by the application of a small DC electric current.

  11. ISOLDE physics overview

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    The On-Line Isotope Mass Separator ISOLDE is a facility dedicated to the production of a large variety of radioactive ion beams for a great number of different experiments in the fields of nuclear and atomic physics, solid-state physics, life sciences and material science. The facility, located at the Proton Synchroton Booster (PSB) of CERN, is operated by CERN for the ISOLDE Collaboration. At ISOLDE, radioactive nuclides are produced in thick high-temperature targets via spallation, fission or fragmentation reactions. The targets are placed in the external proton beam of the PSB, which has an energy of 1 or 1.4 GeV and an intensity of about 2 microA. The target and ion-source together represent a small chemical factory for converting the nuclear reaction products into a radioactive ion beam. An electric field accelerates the ions, which are mass separated and steered to the experiments. Until now more than 600 isotopes of more than 60 elements (Z= 2 to 88) have been produced with half-lives down to milliseco...

  12. Mevva ion source operated in purely gaseous mode

    International Nuclear Information System (INIS)

    Yushkov, G.Y.; MacGill, R.A.; Brown, I. G.

    2003-01-01

    We have operated a vacuum arc ion source in such a way as to form beams of purely gaseous ions. The vacuum arc configuration that is conventionally used to produce intense beams of metal ions was altered so as to form gaseous ion beams, with only minimal changes to the external circuitry and no changes at all internally to the ion source. In our experiments we formed beams from oxygen (O + and O 2 + ), nitrogen (N + and N 2 + ), argon (Ar + ) and carbon dioxide (C + , CO 2 + , O + and O 2 + ) at extraction voltage of 2 to 50 kV. We used a pulsed mode of operation, with beam pulses approximately 50 milliseconds long and repetition rate 10 pulses per second, for a duty cycle of about 50%. Downstream ion beam current as measured by a 5 cm diameter Faraday cup was typically 0.5 mA pulse or about 250 (micro)A time averaged. This time averaged beam current is very similar to that obtained for metal ions when the source is operated in the usual vacuum arc mode. Here we describe the modifications made to the source and the results of our investigations

  13. Uncertainty and sensitivity analysis of control strategies using the benchmark simulation model No1 (BSM1).

    Science.gov (United States)

    Flores-Alsina, Xavier; Rodriguez-Roda, Ignasi; Sin, Gürkan; Gernaey, Krist V

    2009-01-01

    The objective of this paper is to perform an uncertainty and sensitivity analysis of the predictions of the Benchmark Simulation Model (BSM) No. 1, when comparing four activated sludge control strategies. The Monte Carlo simulation technique is used to evaluate the uncertainty in the BSM1 predictions, considering the ASM1 bio-kinetic parameters and influent fractions as input uncertainties while the Effluent Quality Index (EQI) and the Operating Cost Index (OCI) are focused on as model outputs. The resulting Monte Carlo simulations are presented using descriptive statistics indicating the degree of uncertainty in the predicted EQI and OCI. Next, the Standard Regression Coefficients (SRC) method is used for sensitivity analysis to identify which input parameters influence the uncertainty in the EQI predictions the most. The results show that control strategies including an ammonium (S(NH)) controller reduce uncertainty in both overall pollution removal and effluent total Kjeldahl nitrogen. Also, control strategies with an external carbon source reduce the effluent nitrate (S(NO)) uncertainty increasing both their economical cost and variability as a trade-off. Finally, the maximum specific autotrophic growth rate (micro(A)) causes most of the variance in the effluent for all the evaluated control strategies. The influence of denitrification related parameters, e.g. eta(g) (anoxic growth rate correction factor) and eta(h) (anoxic hydrolysis rate correction factor), becomes less important when a S(NO) controller manipulating an external carbon source addition is implemented.

  14. High luminosity operation of large solid angle scintillator arrays in Jefferson Lab Hall A

    International Nuclear Information System (INIS)

    Ran Shneor

    2003-01-01

    This thesis describes selected aspects of high luminosity operation of large solid angle scintillator arrays in Hall A of the CEBAF (Central Electron Beam Accelerator Facility) at TJNAF (Thomas Jefferson National Accelerator Facility ). CEBAF is a high current, high duty factor electron accelerator with a maximum beam energy of about 6 GeV and a maximum current of 200 (micro)A. Operating large solid angle scintillator arrays in high luminosity environment presents several problems such as high singles rates, low signal to noise ratios and shielding requirements. To demonstrate the need for large solid angle and momentum acceptance detectors as a third arm in Hall A, we will give a brief overview of the physics motivating five approved experiments, which utilize scintillator arrays. We will then focus on the design and assembly of these scintillator arrays, with special focus on the two new detector packages built for the Short Range Correlation experiment E01-015. This thesis also contains the description and results of different tests and calibrations which where conducted for these arrays. We also present the description of a number of tests which were done in order to estimate the singles rates, data reconstruction, filtering techniques and shielding required for these counters

  15. Evaluation of radiation protection in some nuclear medicine department

    International Nuclear Information System (INIS)

    Abdelrahim, Yassir Mohammed

    2015-12-01

    This study was carryout to evaluate the radiation protection in nuclear medicine department in Sudan, accordance with the standards international recommendation and code of practice for radiation protection in nuclear medicine, the evaluation was done for three nuclear medicine departments, included direct measurement of dose rate and the contamination level in some areas, were radiation sources, radiation workers and public are involved. The data was collected and analyzed from the results for three nuclear medicine departments that the average reading of ambient dose rate in : outside the door of imaging room (SPECT) 0.18μSv/h in hospital (1)& and 0.19μSv/h in hospital(2) and 0.19μSv/h hospital(3), inside control of imaging room (SPECT) 27.8μSv/h in hospital(1)& 0.14μSv/h in hospital(2)& 14μSv/h in hospital(3), inside the injection room 28.81μSv/h in hospital(1), 0.36μSv/h in hpspital(2), 0.06μSv/h in hospital(3) outside the door of lap, 0.65μSv/h in hospital(1), 0.13μSv/h in hospital(2) & 0.12μSv/h in hospital(3), inside the hot lap, 9.68μSv/h in hospital(1) & 0.30μSv/h in hospital(2) & 0.85 μSv/h in hospital(3), in outsidee the door of waiting room of injected patient 1.41μSv/h in hospital(1)& 0.16μSv/h in hospital(2) & 1.08μSv/h in hospital(3). Avaerge reading of contamination in: Floor of hot lap 44.50 B/cm"2 hospital(1) & 4.42B/cm"2in hospital(2) & 6.22 B/cm"2 in hospital (3) . on the bench tap 186.30 B/cm"2 hospital(1), 19.91 B/cm"2 in hospital(2) & 8.77B/cm"2 in hospital(3) floor of injection room 12.60 B/cm"2 in hospital(1) & 11.70 B/cm"2 in hospital(2) & 13.73 B/cm"2 hospital(3) & table of injection room 13.00 B/cm"2 in hospital(1)& 11.70 B/cm"2in hospital(2)& 13.73 B/cm"2 in hospital & tble of injection room 13.00 B/cm"2 in hospital(1) & 20.40 B/cm"2 in hospital(2) & 23.23 B/cm"2 B/cm"2 in hospital(3) on the shield of working surface 144.30 B/cm in hospital(1)& 47.00 B/cm"2 in hospital(2) & 52.33 B/cm"2 in hospital(3) , and makes check

  16. Biological effects and RAPD analysis of alfalfa (medicago sativa L.) irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Han Weibo; Zhang Yuexue; Tang Fenglan; Liu Jielin; Liu Fengqi; Shang Chen; Kong Fuquan; Wang Xiao; Liu Luxiang

    2011-01-01

    Dry seeds of alfalfa variety Zhaodong were irradiated by fast neutrons generated by linear accelerator with three fluences, 3.60 × 10 11 , 7.10 × 10 11 and 3.54 × 10 12 /cm 2 respectively. Seed germination, growth, and RAPD analysis on the mutation were reported in this study. The results showed that germination vigor and germination rate of irradiated seeds were higher than those of control, but seedling height and root length were reduced with the increase of fluences. When the dosages reached 3.54 × 10 12 /cm 2 , seedling root length decreased by 81.63% compared with the control, but the seedling didn't grow any true leaves except for cotyledon. 36 primers were used in RAPD analysis, and the results showed that the RAPD polymorphic loci rate was 7.25%, 6.52% and 5.80% among the 3.60 × 10 11 /cm 2 , 7.10 × 10 11 /cm 2 and 3.54 × 10 12 /cm 2 treated M 1 plants. RAPD polymorphic loci rate in the 3.60 × 10 11 /cm 2 treated plants was the highest among three treatment. It is concluded that 3.60 × 10 11 /cm 2 could be on optimum fluences for a alfalfa mutation by fast neutrons. (authors)

  17. Effect of combined treatments of neutron radiation and plant growth regulator (GA) on seed germination and growth of rice

    International Nuclear Information System (INIS)

    Xie Chonghua; Wang Dan; Chen Yongjun; Wang Ying; Luo Jie; Liao Wei; Zheng Chun

    2007-01-01

    Rice seeds were irradiated with fast-neutron impulse pile and then were treated with different concentration of GA 3 . The effect of combined treatments on seeds germination and seedling growth were studied. The results showed that lethal pouring dose of neutron radiation on Hongai B and CB was 486 x 10 10 /cm 2 , Mianhui 2009 was 900 x 10 10 /cm 2 and Mianhui 2095 and Minghui 63 were 1350 x 10 10 /cm 2 . Semi-lethal pouring dose (LD 50 ) of neutron radiation on Hongai Band CB was 198-486 x 10 10 /cm 2 , Mianhui 2009 was about 486 x 10 10 /cm 2 , Minghui 63 was 629.49 x 10 10 /cm 2 and Mianhui 2095 is 774.69 x 10 10 /cm 2 . Radiation sensitivity of rice is Hongai B, CB>Mianhui 2009>Minghui 63>Mianhui 2095. GA 3 is a kind of efficient chemical radiation protection. 40 and 80 mg/L are the proper GA 3 concentrations of neutron irradiated rice seeds. (authors)

  18. Effect of Equal Daily Doses Achieved by Different Power Densities of Low-Level Laser Therapy at 635 nm on Open Skin Wound Healing in Normal and Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Róbert Kilík

    2014-01-01

    Full Text Available Background and Objective. Despite the fact that the molecular mechanism of low-level laser therapy (LLLT is not yet known, the exploitation of phototherapy in clinical medicine and surgery is of great interest. The present study investigates the effects of LLLT on open skin wound healing in normal and diabetic rats. Materials and Methods. Four round full-thickness skin wounds on dorsum were performed in male adult nondiabetic (n=24 and diabetic (n=24 Sprague–Dawley rats. AlGaInP (635 nm, wavelength; 5 J/cm2, daily dose was used to deliver power densities of 1, 5, and 15 mW/cm2 three times daily until euthanasia. Results. PMNL infiltration was lower in the irradiated groups (15 mW/cm2. The synthesis and organisation of collagen fibres were consecutively enhanced in the 5 mW/cm2 and 15 mW/cm2 groups compared to the others in nondiabetic rats. In the diabetic group the only significant difference was recorded in the ratio PMNL/Ma at 15 mW/cm2. A significant difference in the number of newly formed capillaries in the irradiated group (5, 15 mW/cm2 was recorded on day six after injury compared to the control group. Conclusion. LLLT confers a protective effect against excessive inflammatory tissue response; it stimulates neovascularization and the early formation of collagen fibres.

  19. Hydrocortisone Diffusion Through Synthetic Membrane, Mouse Skin, and Epiderm™ Cultured Skin.

    Science.gov (United States)

    Christensen, John Mark; Chuong, Monica Chang; Le, Hang; Pham, Loan; Bendas, Ehab

    2011-03-01

    OBJECTIVES: The penetration of hydrocortisone (HC) from six topical over-the-counter products along with one prescription cream through cultured normal human-derived epidermal keratinocytes (Epiderm™), mouse skin and synthetic nylon membrane was performed as well as the effect hydrating the skin by pre-washing was explored using the Upright Franz Cell. METHOD AND RESULTS: Permeation of HC through EpiDerm™, mouse skin and synthetic membrane was highest with the topical HC gel formulation with prewash treatment of the membranes among seven products evaluated, 198 ± 32 µg/cm(2), 746.32 ± 12.43 µg/cm(2), and 1882 ± 395.18 µg/cm(2), respectively. Pre-washing to hydrate the skin enhanced HC penetration through EpiDerm™ and mouse skin. The 24-hour HC released from topical gel with prewash treatment was 198.495 ± 32 µg/cm(2) and 746.32 ± 12.43 µg/cm(2) while without prewash, the 24-h HC released from topical gel was 67.2 ± 7.41 µg/cm(2) and 653.43 ± 85.62 µg/cm(2) though EpiDerm™ and mouse skin, respectively. HC penetration through synthetic membrane was ten times greater than through mouse skin and EpiDerm™. Generally, the shape, pattern, and rank order of HC diffusion from each commercial product was similar through each membrane.

  20. Effect of the thickness of the anode electrode catalyst layers on the performance in direct methanol fuel cells

    Science.gov (United States)

    Glass, Dean E.; Olah, George A.; Prakash, G. K. Surya

    2017-06-01

    For the large scale fuel cell manufacture, the catalyst loading and layer thickness are critical factors affecting the performance and cost of membrane electrode assemblies (MEAs). The influence of catalyst layer thicknesses at the anode of a PEM based direct methanol fuel cell (DMFC) has been investigated. Catalysts were applied with the drawdown method with varied thicknesses ranging from 1 mil to 8 mils (1 mil = 25.4 μm) with a Pt/Ru anode loading of 0.25 mg cm-2 to 2.0 mg cm-2. The MEAs with the thicker individual layers (8 mils and 4 mils) performed better overall compared to the those with the thinner layers (1 mil and painted). The peak power densities for the different loading levels followed an exponential decrease of Pt/Ru utilization at the higher loading levels. The highest power density achieved was 49 mW cm-2 with the 4 mil layers at 2.0 mg cm-2 catalyst loading whereas the highest normalized power density was 116 mW mg-1 with the 8 mil layers at 0.25 mg cm-2 loading. The 8 mil drawdowns displayed a 50% and 23% increase in normalized power density compared to the 1 mil drawdowns at 0.25 mg cm-2 and 0.5 mg cm-2 loadings, respectively.

  1. Controlled delivery of ropinirole hydrochloride through skin using modulated iontophoresis and microneedles.

    Science.gov (United States)

    Singh, Neha D; Banga, Ajay K

    2013-05-01

    The objective of this study was to investigate the effect of modulated current application using iontophoresis- and microneedle-mediated delivery on transdermal permeation of ropinirole hydrochloride. AdminPatch® microneedles and microchannels formed by them were characterized by scanning electron microscopy, dye staining and confocal microscopy. In vitro permeation studies were carried out using Franz diffusion cells, and skin extraction was used to quantify drug in underlying skin. Effect of microneedle pore density and ions in donor formulation was studied. Active enhancement techniques, continuous iontophoresis (74.13 ± 2.20 µg/cm(2)) and microneedles (66.97 ± 10.39 µg/cm(2)), significantly increased the permeation of drug with respect to passive delivery (8.25 ± 2.41 µg/cm(2)). Modulated iontophoresis could control the amount of drug delivered at a given time point with the highest flux being 5.12 ± 1.70 µg/cm(2)/h (5-7 h) and 5.99 ± 0.81 µg/cm(2)/h (20-22 h). Combination of modulated iontophoresis and microneedles (46.50 ± 6.46 µg/cm(2)) showed significantly higher delivery of ropinirole hydrochloride compared to modulated iontophoresis alone (84.91 ± 9.21 µg/cm(2)). Modulated iontophoresis can help in maintaining precise control over ropinirole hydrochloride delivery for dose titration in Parkinson's disease therapy and deliver therapeutic amounts over a suitable patch area and time.

  2. [Light scattering extinction properties of atmospheric particle and pollution characteristics in hazy weather in Hangzhou].

    Science.gov (United States)

    Xu, Chang; Ye, Hui; Shen, Jian-Dong; Sun, Hong-Liang; Hong, Sheng-Mao; Jiao, Li; Huang, Kan

    2014-12-01

    In order to evaluate the influence of particle scattering on visibility, light scattering coefficient, particle concentrations and meteorological factor were simultaneously monitored from July 2011 to June 2012 in Hangzhou. Daily scattering coefficients ranged from 108.4 to 1 098.1 Mm(-1), with an annual average concentration of 428.6 Mm(-1) ± 200.2 Mm(-1). Seasonal variation of scattering coefficients was significant, with the highest concentrations observed in autumn and winter and the lowest in summer. It was found there were two peaks for the average diurnal variations of the scattering coefficient, which could be observed at 08:00 and 21:00. The scattering efficiencies of PM2.5 and PM10 were 7.6 m2 x g(-1) and 4.4 m2 x g(-1), respectively. The particle scattering was about 90.2 percent of the total light extinction. The scattering coefficients were 684.4 Mm(-1) ± 218.1 Mm(-1) and 1 095.4 Mm(-1) ± 397.7 Mm(-1) in hazy and heavy hazy days, respectively, which were 2.6 and 4.2 times as high as in non-hazy weather, indicating that particle scattering is the main factor for visibility degradation and the occurrence of hazy weather in Hangzhou.

  3. Low-cost stainless-steel wool anodes modified with polyaniline and polypyrrole for high-performance microbial fuel cells

    Science.gov (United States)

    Sonawane, Jayesh M.; Patil, Sunil A.; Ghosh, Prakash C.; Adeloju, Samuel B.

    2018-03-01

    A conducting polymer coated stainless-steel wool (SS-W) is proposed for use as a low-cost anode for microbial fuel cells (MFCs). When coated with polyaniline (PANi) and polypyrrole (PPy), the pristine SS-W, SS/PANi-W and SS/PPy-W anodes produced maximum current densities of 0.30 ± 0.04, 0.67 ± 0.05, 0.56 ± 0.07 mA cm-2, respectively, in air-cathode MFCs. Also, based on achieved power density, both SS/PANi-W and SS/PPy-W achieved 0.288 ± 0.036 mW cm-2 and 0.187 ± 0.017 mW cm-2, respectively, which were superior to 0.127 ± 0.011 mW cm-2 obtained with pristine SS-W. Further, in comparison with SS-P based anodes, all SS-W based anodes gave improved power densities under similar experimental conditions by at least 70%. Moreover, the charge transfer resistance of the SS-W was much lower (240 ± 25 Ω cm-2) than for the SS-P (3192 ± 239 Ω cm-2). The j0(apparent) values obtained for SS/PANi-W (0.098 ± 0.007 mA cm-2) and SS/PPy-W (0.036 ± 0.004 mA cm-2) anodes were also much higher than that of the pristine SS-W (0.020 ± 0.005 mA cm-2), as well as than those of all SS-P based anodes. The observed enhancement of the bioelectrocatalytic performances were well supported by physicochemical and electrochemical characterisation.

  4. Use of laser-UV for inactivation of virus in blood products

    International Nuclear Information System (INIS)

    Prodouz, K.N.; Fratantoni, J.C.; Boone, E.J.; Bonner, R.F.

    1987-01-01

    Inactivation of virus by UV radiation was examined as a potential method for sterilization of blood products. Samples of attenuated poliovirus, platelets and plasma were uniformly irradiated with a XeCl excimer laser that delivered 40 nsec pulses of UV at 308 nm (UVB308). Intensities and exposure does were varied from 0.11 to 1.40 MW/cm2 and 0.51 to 56.0 J/cm2, respectively. In studies conducted with low intensity UVB308 (less than or equal to 0.17 MW/cm2), using exposure doses greater than or equal to 10.8 J/cm2, it was possible to inactivate poliovirus by 4 to 6 log10. Platelets irradiated with doses less than or equal to 21.5 J/cm2 exhibited minimal damage as assessed by aggregation activity and spontaneous release of serotonin. Examination of the coagulation activity of irradiated plasma indicated that exposure doses less than or equal to 21.5 J/cm2 resulted in less than 20% increase in prothrombin and partial thromboplastin times. The use of UVB308 at a higher intensity (1.4 MW/cm2) over a similar range of exposure doses did not enhance viral inactivation but did result in increased damage to platelet and plasma proteins. These results demonstrate that at 308 nm there exists a window of efficacy for exposure doses between 10.8 and 21.5 J/cm2 and peak intensities less than or equal to 0.17 MW/cm2 in which a hardy virus is significantly inactivated and platelets and plasma proteins are, by functional criteria, minimally affected. Increased viral inactivation cannot be accomplished with higher UV intensities and will require additional or alternate measures

  5. Radiological control in a mine with a naturally-occurring radioactive material -NORM: III assessment of removable surface contamination in a pilot plant

    International Nuclear Information System (INIS)

    Pereira, W.S.; Py Junior, D.A.; Silva, A.C.A.; Garcia Filho, O.

    2013-01-01

    Ore Treatment Unit (OUT) possesses a process laboratory. Considering the uranium ore processing, this laboratory works in close cooperation with the Radiation Protection Service of the Unit. In the year of 2009 a pilot plant for the development of solvent uranium extraction from the phosphate ore of the mine of Santa Quiteria city, in Ceara State, Brazil was developed. In this kind of plant the surface contamination may cause contamination for Occupational Exposed Individuals (OEI). In order to control this kind of contamination and offer a safety work's condition for OEIs, a monitoring program of transferable contamination using swab samples was developed. 162 swabs were made. For the alpha emitters the monitoring results varied from 0.001 Bq cm -2 to 0.014 Bq cm -2 , with average value of 0.002 Bq cm -2 . For beta emitters the results varied from 0.010 Bq cm -2 to 0.031 Bq cm -2 with average equal to 0.011 Bq cm -2 . For alpha emitters, 87.65 % of the results were below 0.004 Bq cm -2 , values that are one order of magnitude smaller than the limit and the maximum value stayed in 35 % of the limit for an object to be considered contaminated. For beta emitters, 90 % of the results were below 0.010 Bq cm -2 that corresponds to 25 % of the limit and 100 % were below 0.031 Bq cm -2 below the limit for an object to be considered contaminated. In both cases any object monitored during the operation, was not considered contaminated, proving the good practices employed in the laboratory, resultant of the good planning of the Radiation Protection Service for the operations' process. (author)

  6. Platelet adhesion and plasma protein adsorption control of collagen surfaces by He+ ion implantation

    International Nuclear Information System (INIS)

    Kurotobi, K.; Suzuki, Y.; Nakajima, H.; Suzuki, H.; Iwaki, M.

    2003-01-01

    He + ion implanted collagen-coated tubes with a fluence of 1 x 10 14 ions/cm 2 were exhibited antithrombogenicity. To investigate the mechanisms of antithrombogenicity of these samples, plasma protein adsorption assay and platelet adhesion experiments were performed. The adsorption of fibrinogen (Fg) and von Willebrand factor (vWf) was minimum on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 . Platelet adhesion (using platelet rich plasma) was inhibited on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was accelerated on the untreated collagen and ion implanted collagen with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Platelet activation with washed platelets was observed on untreated collagen and He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was inhibited with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Generally, platelets can react with a specific ligand inside the collagen (GFOGER sequence). The results of platelets adhesion experiments using washed platelets indicated that there were no ligands such as GFOGER on the He + ion implanted collagen over a fluence of 1 x 10 13 ions/cm 2 . On the 1 x 10 14 ions/cm 2 implanted collagen, no platelet activation was observed due to the influence of plasma proteins. >From the above, it is concluded that the decrease of adsorbed Fg and vWf caused the antithrombogenicity of He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and that plasma protein adsorption took an important role repairing the graft surface

  7. EXPERIMENTAL CONFIRMATION FOR SELECTION OF IRRADIATION REGIMENS FOR INTRAPERITONEAL PHOTODYNAMIC THERAPY WITH PORPHYRIN AND PHTHALOCYANINE PHOTOSENSITIZERS

    Directory of Open Access Journals (Sweden)

    A. A. Pankratov

    2017-01-01

    Full Text Available Optimized irradiation regimens for intraperitoneal photodynamic therapy with porphyrin and phthalocyanine photosensitizers are determined in in vitro and in vivo studies.The experimental  study on НЕр2 cell line showed that reduce of power density for constant  light dose increased significantly the efficacy of photodynamic therapy (the reduce of power density from 20-80 mW/cm2 to 10 mW/cm2 had the same results (90% cell death for half as much concentration of the photosensitizer.The obtained results were confirmed in vivo in mice with grafted tumor S-37. For light dose of 90 J/cm2  and power density of 25 mW/cm2 none of animals in the experimental  group had total resorption of the tumor. For the same light dose and decrease  of power density to 12 mW/cm2  total tumor resorption was achieved in 34% of animals, 66% of animals died from phototoxic  shock. For twofold decrease  of light dose – to 45 J/cm2  with the same low-intensity power density (12 mW/cm2 we managed total tumor resorption in 100% of animals.In the following studies of optimized irradiation regimen for intrapleural photodynamic therapy the reaction of intact peritoneum of rats on photodynamic exposure was assessed and optimized parameters of laser irradiation, which did not cause necrosis and intense inflammatory reaction of peritoneum, were determined – light dose of 10 J/cm2  with power density of mW/cm2.Thus, the reasonability for use of low-intensity regimens of irradiation for intraperitoneal photodynamic therapy was confirmed experimentally with possibility of high efficacy of treatment without inflammatory reactions of peritoneum.

  8. Ethnic differences in mammographic densities: an Asian cross-sectional study.

    Directory of Open Access Journals (Sweden)

    Shivaani Mariapun

    Full Text Available BACKGROUND: Mammographic density is a strong risk factor for breast cancer and is highly variable, but, to date, few studies have examined density in Asian women, particularly those in low and middle-income Asian countries where genetic and lifestyle determinants may be significantly different. METHODS: A total of 1,240 women who attended an opportunistic mammogram screening programme were eligible for analysis. Mammographic density was estimated using a fully-automated thresholding method and differences across ethnic groups were examined using linear regression in 205 randomly selected Chinese women, 138 Malay and 199 Indian women. RESULTS: Percent density was significantly higher in Chinese women (28.5%; 95% CI 27.0%, 30.0% compared to Malay (24.2%; 95% CI 22.5%, 26.0% and Indian (24.3%; 95% CI 22.8%, 25.7% women (p<0.001, after adjustment for age, BMI, menopausal status, parity and age at first full term pregnancy. Correspondingly, adjusted nondense area was significantly lower in Chinese (72.2cm2; 95% CI 67.9cm2, 76.5cm2 women compared to Malay (92.1cm2; 95% CI 86.9cm2, 97.2cm2 and Indian (97.7cm2; 95% CI 93.4cm2, 101.9cm2 women (p<0.001, but dense area did not differ across the three ethnic groups. CONCLUSIONS: Our study shows that higher percent density and lower nondense area reflect the higher incidence of breast cancer in Chinese compared to Malay and Indian women in Malaysia. Known lifestyle determinants of mammographic density do not fully account for the ethnic variations observed in mammographic density in this Asian cohort.

  9. Ethnic Differences in Mammographic Densities: An Asian Cross-Sectional Study

    Science.gov (United States)

    Mariapun, Shivaani; Li, Jingmei; Yip, Cheng Har; Taib, Nur Aishah Mohd; Teo, Soo-Hwang

    2015-01-01

    Background Mammographic density is a strong risk factor for breast cancer and is highly variable, but, to date, few studies have examined density in Asian women, particularly those in low and middle-income Asian countries where genetic and lifestyle determinants may be significantly different. Methods A total of 1,240 women who attended an opportunistic mammogram screening programme were eligible for analysis. Mammographic density was estimated using a fully-automated thresholding method and differences across ethnic groups were examined using linear regression in 205 randomly selected Chinese women, 138 Malay and 199 Indian women. Results Percent density was significantly higher in Chinese women (28.5%; 95% CI 27.0%, 30.0%) compared to Malay (24.2%; 95% CI 22.5%, 26.0%) and Indian (24.3%; 95% CI 22.8%, 25.7%) women (p<0.001), after adjustment for age, BMI, menopausal status, parity and age at first full term pregnancy. Correspondingly, adjusted nondense area was significantly lower in Chinese (72.2cm2; 95% CI 67.9cm2, 76.5cm2) women compared to Malay (92.1cm2; 95% CI 86.9cm2, 97.2cm2) and Indian (97.7cm2; 95% CI 93.4cm2, 101.9cm2) women (p<0.001), but dense area did not differ across the three ethnic groups. Conclusions Our study shows that higher percent density and lower nondense area reflect the higher incidence of breast cancer in Chinese compared to Malay and Indian women in Malaysia. Known lifestyle determinants of mammographic density do not fully account for the ethnic variations observed in mammographic density in this Asian cohort. PMID:25659139

  10. The Time-of-Flight Detector for the ALICE experiment

    CERN Document Server

    Williams, M C S

    2002-01-01

    The Multigap Resistive Plate Chamber (MRPC) will be used to build a large Time-of-Flight detector for the ALICEexperiment. It will cover an area of 150 m2 consisting of 160,000 channels of 3.5 x 2.5 cm2 read-out pads. We present the results of the last 2 years of R&D during which we investigated problems associated with scaling up from single cells of 3 x 3 cm2 to strips with active area of 7 × 120 cm2 read out with 96 pads.

  11. Analysis of influence of fast neutron fluence irradiated to Beryllium element of The RSG-GAS reactor

    International Nuclear Information System (INIS)

    Sri Kuntjoro

    2010-01-01

    Analysis of influence fast neutron fluence irradiated to the RSG-GAS beryllium reflector have been done. Methods of analysis was carried out by measuring fluxes neutron in beryllium element and block position that function as reflector.The calculation done for determination it is there any influence of neutron as long as beryllium in the core. Besides that, visualization done to make sure it there is any deformation at beryllium as effect of irradiation. Fluxes and fluences of beryllium element measurement result in 200 kW reactor power are 2.30E+07 n/cm 2 .sec and 4.19E+17 n/cm 2 in position E-2, 3.70E+07 n/cm 2 s and 6.74E+17 n/cm 2 in position J-8, 2.19E+12 n/cm 2 s and 3.99E+22 n/cm 2 in position. Measurement results in the position B-3 are 2.12E+12 n/cm 2 s and 3.86E+22 n/cm 2 in position G-10 respectively. Other result are fluxes and fluence in beryllium block, those are 5,02E+07 n/cm 2 s and 9,15E+17 n/cm 2 in position (5-6), and 2,32E+07 n/cm 2 s and 4,23E+17 n/cm 2 in position (C-D). Deformation (L/L) results for beryllium element are 1,12E-08 in position E-2, 1,84E-08 in position J-8, 1,60E-03 in position B-3, and 1,55E-03 in position G-10. In beryllium block deformation results are 2,52E-08 in position (5-6) and 1,13E-08 in position (C-D). Those results are shown unseen deformation in beryllium element and beryllium block and demonstrably by visual observation in reactor hot cell. (author)

  12. SU-E-T-380: Evaluation of BEBIG HDR 60Co System for AccuBoost Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zehtabian, M; Sina, S [Shiraz University, Shiraz, Fars (Iran, Islamic Republic of); Rivard, M [Tufts University School of Medicine, Boston, MA (United States); Meigooni, A Soleimani [Comprehensive Cancer Center of Nevada, Las Vegas, Nevada (United States)

    2015-06-15

    Purpose: In this project, the possibility of utilizing the BEBIG 60Co HDR system for AccuBoostTM treatment has been evaluated. Methods: Dose distributions in various breast sizes have been calculated for both Co-60 and Ir-192 sources using the MCNP5 code. These calculations were performed in breast tissues with thicknesses of 4cm, 6cm, and 8cm. The initial calculations were performed with the same applicator dimensions as the existing applicators used with the HDR Ir-192 system. The activity of the Co-60 source was selected such that the dose at the breast center was the same as the values from 192Ir. Then, the applicator thicknesses were increased to twice of those used with HDR Ir-192 system, for reducing skin and chest doses by Co-60 system. Dose to breast skin and chest wall were compared for both applicators types, with and without inclusion of a focusing cone at the applicator center. Results: The results showed that loading HDR Co-60 source inside the thin applicators impose higher doses to breast skin and chest wall compared to the 192Ir source. The area of the chest wall covered by 10Gy when treated by Co-60 with the thin and thick applicators, or treated by Ir-192 with thin applicator are 79cm2, 39cm2, and 3.8cm2, respectively. These values are reduced to 34cm2, 0cm2, and 0cm2 by using the focusing cone. It is worth noting that the breast skin areas covered by the 60Gy isodose line are 9.9cm2 and 7.8cm2 for Co-60 with the thin and thick applicators, respectively, while it is 20cm2 for Ir-192 when no focusing cone is present. These values are 0cm2, 0cm2, and 11cm2 in the presence of the focusing cone. Conclusion: The results indicate that using Co-60 with the thicker applicators is beneficial because of the higher half-life of Co-60, and the reduced maximum skin dose when compared with Ir-192.

  13. Preliminary shielding design evaluation for reactor assembly of SMART

    International Nuclear Information System (INIS)

    Kim, Kyo Youn; Kang, Chang M.; Kim, Ha Yong; Zee, Sung Quun; Chang, Moon Hee

    1999-03-01

    This report describes a preliminary evaluations of SMART shielding design near the reactor core by using the DORT two-dimensional discrete ordinates transport code. The results indicate that maximum neutron fluence at the bottom of reactor vessel is 1.64x10 17 n/cm 2 and that on the radial surface of reactor vessel is 6.71x10 16 n/cm 2 . These results meet the requirement, 1.0x10 20 n/cm 2 , in 10 CFR 50.61 and the integrity of SMART reactor vessel is confirmed during the lifetime of reactor. (Author). 20 refs., 11 tabs., 8 figs

  14. Design of an advanced bundle divertor for the Demonstration Tokamak Hybrid Reactor

    International Nuclear Information System (INIS)

    Yang, T.F.; Lee, A.Y.; Ruck, G.W.; Prevenslik, T.V.; Smeltzer, G.

    1979-01-01

    The conclusion of this work is that a bundle divertor, using an improved method of designing the magnetic field configuration, is feasible for the Demonstration Tokamak Hybrid Reactor (DTHR) investigated by Westinghouse. The most significant achievement of this design is the reduction in current density (1 kA/cm 2 ) in the divertor coils in comparison to the overall averaged current densities per tesla of field to be nulled for DITE (25 kA/cm 2 ) and for ISX-B 2 (11 kA/cm 2 ). Therefore, superconducting magnets can be built into the tight space available with a sound mechanical structure

  15. The choice of sensitive skin layer responsible for aftereffects of daily irradiation of the skin

    International Nuclear Information System (INIS)

    Keirim-Markus, I.B.

    1992-01-01

    The choice of sensitive human skin layer manifesting in delayed period after daily irradiation of the human skin (stochastic and determined effects) was evaluated. It was established that delayed aftereffects of daily radiation of the skin manifested as epidem damages. This layer of papilla derma of 10-15 mg/cm 2 thick situated at the great part of body surface, 15 mg/cm 2 on dorsal side of hands and 40 mg/cm 2 on palms and pillows of the fingers. Sensitive layer of skin dosimeter for a control of daily irradiation of people must have the same geometry

  16. SU-F-T-610: Comparison of Output Factors for Small Radiation Fields Used in SBRT Treatment

    International Nuclear Information System (INIS)

    Gupta, R; Eldib, A; Li, J; Ma, C

    2016-01-01

    Purpose: In order to fundamentally understand our previous dose verification results between measurements and calculations from treatment planning system (TPS) for SBRT plans for different sized targets, the goal of the present work was to compare output factors for small fields measured using EDR2 films with TPS and Monet Carlo (MC) simulations. Methods: 6MV beam was delivered to EDR2 films for each of the following field sizes; 1×1 cm"2, 1.5×1.5 cm"2, 2×2 cm"2, 3×3 cm"2, 4×4 cm"2, 5×5 cm"2 and 10×10 cm"2. The films were developed in a film processer, then scanned with a Vidar VXR-16 scanner and analyzed using RIT113 version 6.1. A standard calibration curve was obtained with the 6MV beam and was used to get absolute dose for measured field sizes. Similar plans for all fields sizes mentioned above were generated using Eclipse with the Analytical Anisotropic Algorithm. Similarly, MC simulations were carried out using the MCSIM, an in-house MC code for different field sizes. Output factors normalized to 10×10 cm"2 reference field were calculated for different field sizes in all the three cases and compared. Results: For field sizes ranging from 1×1 cm"2 to 2×2 cm"2, the differences in output factors between measurements (films), TPS and MC simulations were within 0.22%. For field sizes ranging from 3×3cm"2 to 5×5cm"2, differences in output factors were within 0.10%. Conclusion: No clinically significant difference was obtained in output factors for different field sizes acquired from films, TPS and MC simulations. Our results showed that the output factors are predicted accurately from TPS when compared to the actual measurements and superior dose calculation Monte Carlo method. This study would help us in understanding our previously obtained dose verification results for small fields used in the SBRT treatment.

  17. INFLUENCE MATURATION OF VEAL ON THE MICROBIOLOGICAL AND PHYSICAL INDICATORS

    Directory of Open Access Journals (Sweden)

    Simona Kunová

    2015-06-01

    Full Text Available The aim of the present study was to evaluate microbial and pH changes in veal meat during maturation. Total viable counts, coliform bacteria and pH changes in chilling meat were evaluated after 24 hours, 7 days and 14 days of meat maturation. There were analysed 8 samples of veal meeat. Results of microbiological analysis were compared with Commission regulation (EC No 2073/2005 on microbiological criteria for foodstuffs. Total viable counts (TVC in samples after 24 hours of chilling ranged from 2.02 log CFU.cm-to 4.21 log CFU.cm-2 (1.64 . 104 CFU.cm-2. The average number of TVC after 24 hours of meat maturation was 3.27 log CFU.cm-2, coliform bacteria (CB after 24 hours were lower than than 1 log cfu.cm-2 in five samples, and the highest number of coliform bacteria was 1.65 log cfu.cm-2, average number of CB was 1.13 log cfu.cm-2. pH values in samples after 24 hours of maturation were in range from 6.6 to 7.0, average pH value was 6.8. TVC in samples after 7 days of chilling ranged from 3.09 log CFU.cm-2 to 4.01 log CFU.cm-2, the average number of TVC after 7 days of storage was 3.39 log CFU.cm-2. CB after 7 days of meat maturation were lower than 1 log CFU cm-2 in three samples, the highest value of CB was 2.07 log CFU cm-2, the average value of CB in samples after 7 days of meat chilling was 1.03 log CFU cm-2. pH values of meat after 7 days of maturation ranged from 5.5 to 6.1. The average pH value of samples after 7 days of storage was 5.73 pH values of meat after 14 days of maturation ranged from 6.0 to 6.4. The average pH value of samples after 14 days of storage was 6.16.

  18. Properties of the ablation process for excimer laser ablation of Y1Ba2Cu3O7

    International Nuclear Information System (INIS)

    Neifeld, R.A.; Potenziani, E.; Sinclair, W.R.; Hill III, W.T.; Turner, B.; Pinkas, A.

    1991-01-01

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm 2 . Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm 2 . Several of the parameters measured vary rapidly in the 1--5 J/cm 2 range. Variation in these parameters strongly influences the properties of films grown by this technique

  19. Physical state of implanted W in copper

    International Nuclear Information System (INIS)

    Borders, J.A.; Cullis, A.G.; Poate, J.M.

    1975-01-01

    Transmission electron microscopy and 4 He ion channeling measurements were combined to investigate the physical state of implanted W in copper. For 60 0 K implantations of 2 x 10 15 W cm -2 , W is found to be 100 percent substitutional and is still 90 percent substitutional for a dose of 10 16 W cm -2 . Implantation of 10 17 W cm -2 produces a thin disordered surface layer of W and Cu with the W occupying no regular lattice site. On annealing to 600 0 C, W precipitates are formed with dimensions of a few hundred A and certain preferred orientations in the Cu lattice. (auth)

  20. EVALUATION OF THE DISINFECTION EFFECTIVENESS AT MEAT PROCESSING BY THE TWO METHODS

    Directory of Open Access Journals (Sweden)

    Simona Kunová,Miroslava Kačániová

    2015-06-01

    Full Text Available The aim of this article was the control of disinfection in selected meat processing-plant by two methods – swabbing method and The 3M™ Petrifilm™ plates. Samples were collected within three months (September, October, November 2014. Together 54 samples selected surfaces were collected. Each month six samples were collected using imprint method with Petrifilm plates on total count of microorganisms, 6 samples using imprint method with Petrifilm plates on the number of coliforms and 6 samples using sterile swab method. Samples were collected from the workbench, conveyor belt, cutting blades, meat grinder, wall and knife. Total viable counts (TVC and coliform bacteria (CB were determined in samples. The values of TVC in September obtained by swabbing method were higher than allowable limit in sample no. 1 (3.70×102 CFU.cm-2 and in sample no. 4 (3.35×101 KTJ.cm-2. The values of TVC obtained by Petrifilm plates were lower than 10 CFU.cm-2 in all samples. Values of CB obtained by Petrifilm plates were lower than 1 CFU.cm-2 in all samples, CB obtained by swabbing method was 1.6×101 CFU.cm-2 in sample no. 6. Values of TVC obtained in October by Petrifilm plates and also by swabbing method were higher than permissible limit (< 10 CFU.cm-2 in sample no. 2 and sample no. 4. Values of CB obtained by Petrifilm plates were lower than 1 CFU.cm-2 in all samples, CB obtained by swabbing method was 3,65×101 CFU.cm-2 in sample no. 3, value of CB obtained by swab method in sample no. 3 does not meet requirements of internal company standards. Values of TVC obtained in November by Petrifilm plates were lower than 10 CFU.cm-2 in all samples. TVC otained by swab method were 1,25×101 CFU.cm-2 in sample no. 3 and 3,25×101 CFU.cm-2 in sample no. 4. Samples were not in accordance with requirements of internal company standards. Values of CB obtained in November by Petrifilm plates and by swabbing method were after disinfection lower than 1 CFU.cm-2 in all

  1. Effect of two lasers on the polymerization of composite resins: single vs combination.

    Science.gov (United States)

    Ro, Jung-Hoon; Son, Sung-Ae; Park, Jeong-kil; Jeon, Gye-Rok; Ko, Ching-Chang; Kwon, Yong Hoon

    2015-07-01

    The selection of a light-curing unit for the curing composite resins is important to achieve best outcomes. The purpose of the present study was to test lasers of 457 and 473 nm alone or in combination under different light conditions with respect to the cure of composite resins. Four different composite resins were light cured using five different laser combinations (530 mW/cm(2) 457 nm only, 530 mW/cm(2) 473 nm only, 177 mW/cm(2) 457 + 177 mW/cm(2) 473 nm, 265 mW/cm(2) 457 + 265 mW/cm(2) 473 nm, and 354 mW/cm(2) 457 + 354 mW/cm(2) 473 nm). Microhardness and polymerization shrinkage were evaluated. A light-emitting diode (LED) unit was used for comparison purposes. On top surfaces, after aging for 24 h, microhardness achieved using the LED unit and the lasers with different conditions ranged 42.4-65.5 and 38.9-67.7 Hv, respectively, and on bottom surfaces, corresponding ranges were 25.2-56.1 and 18.5-55.7 Hv, respectively. Of the conditions used, 354 mW/cm(2) 457 nm + 354 mW/cm(2) 473 nm produced the highest bottom microhardness (33.8-55.6 Hv). On top and bottom surfaces, microhardness by the lowest total light intensity, 354 (177 × 2) mW/cm(2), ranged 39.0-60.5 and 18.5-52.8 Hv, respectively. Generally, 530 mW/cm(2) at 457 nm produced the lowest polymerization shrinkage. However, shrinkage values obtained using all five laser conditions were similar. The study shows the lasers of 457 and 473 nm are useful for curing composite resins alone or in combination at much lower light intensities than the LED unit.

  2. Novel technique of making thin target foil of high density material via rolling method

    Science.gov (United States)

    Gupta, C. K.; Rohilla, Aman; Singh, R. P.; Singh, Gurjot; Chamoli, S. K.

    2018-05-01

    The conventional rolling method fails to yield good quality thin foils of thicknesses less than 2 mg/cm2 for high density materials with Z ≥ 70 (e.g. gold, lead). A special and improved technique has been developed to obtain such low thickness good quality gold foils by rolling method. Using this technique thin gold foils of thickness in the range of 0.850-2.5 mg/cm2 were obtained in the present work. By making use of alcohol during rolling, foils of thickness 1 mg/cm2 can be obtained in shorter time with less effort.

  3. Limnology of freshwater lakes of Schirmacher Oasis, East Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Parulekar, A.H.

    taxonomic groups with minimum and maximum faunal density of 43 and 823 individuals in 10 cm/2 respectively was recorded from covered and uncovered sediments. Faunal density showed a strong correlation with organic carbon content and the sediment texture...

  4. Errors due to non-uniform distribution of fat in dual X-ray absorptiometry of the lumbar spine

    International Nuclear Information System (INIS)

    Tothill, P.; Pye, D.W.

    1992-01-01

    Errors in spinal dual X-ray absorptiometry (DXA) were studied by analysing X-ray CT scans taken for diagnostic purposes on 20 patients representing a wide range of fat content. The mean difference between the fat thickness over the vertebral bodies and that over a background area in antero-posterior (AP) scanning was 6.7 ± 8.1 mm for men and 13.4 ± 4.7 mm for women. For AP scanning a non-uniform fat distribution leads to a mean overestimate of 0.029 g/cm 2 for men and 0.057 g/cm 2 for women. The error exceeded 0.1 g/cm 2 in 10% of slices. For lateral scanning the error exceeded 0.1 g/cm 2 (about 15% of normal) in a quarter of slices. (author)

  5. SR TXRF: performances and perspectives of a dedicated synchrotron beamline

    International Nuclear Information System (INIS)

    Comin, F.; Apostolo, G.

    2000-01-01

    In principle the brilliance of synchrotron radiation x-ray beams combined with a high degree of linear polarization allows to reach at the same time low LLDs, mapping of the impurity distribution and chemical identification for elements as light as Na. The TXRF facility at the European synchrotron radiation facility is installed along a beamline dedicated to industry and is designed to reach ultimate detection limits of 6 x 10 7 at/cm 2 in selected areas, or to map the concentration of contaminants with LLD in the scale 10 9 at/cm 2 . In the present configuration the facility works in vacuum with a single element detector. Loading, unloading and pump down of wafers is completely automatic. Typical DDLs are of few 10 9 at/cm 2 for Na and Al and 10 8 at/cm 2 for transition metals. Absorption spectra (XANES and EXAFS) of TM help in the defining the chemistry of the contaminant. (author)

  6. Shigellosis Outbreak in Jimma Town, Oromiya Regional State ...

    African Journals Online (AJOL)

    user

    management agencies, especially the World Health ... (GMPs). 1Department of Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, ... comprising an area of 100 cm2 lean meat were collected ...

  7. Nano-aggregates of cobalt nickel oxysulfide as a high-performance electrode material for supercapacitors

    Science.gov (United States)

    Liu, Lifeng

    2013-11-01

    Nano-aggregates of cobalt nickel oxysulfide (CoNi)OxSy have been synthesized by hydrothermal processing and exhibited specific and areal capacitance as high as 592 F g-1 and 1628 mF cm-2, respectively, at a current density of 0.5 A g-1/1.375 mA cm-2. They also show high capacitance retention upon extended cycling at high rates.Nano-aggregates of cobalt nickel oxysulfide (CoNi)OxSy have been synthesized by hydrothermal processing and exhibited specific and areal capacitance as high as 592 F g-1 and 1628 mF cm-2, respectively, at a current density of 0.5 A g-1/1.375 mA cm-2. They also show high capacitance retention upon extended cycling at high rates. Electronic supplementary information (ESI) available: Experimental details; supplementary tables. See DOI: 10.1039/c3nr03533f

  8. Gamma-ray observations of supernovae SN1987A

    International Nuclear Information System (INIS)

    Souza, C.A.W.; Neri, J.A.C.F.; Jayanthi, U.B.

    1988-01-01

    Theoretical investigations of supernovae explosions predict a high emission of gamma rays (∼ 10 -2 photons.cm -2 .s -1 ) beginning around 300 days after explosion. A balloon-borne experiment was flown in October, 1987, to observe this emission. The payload carried 4 phoswich detectors of BGO/CsI and NaI/CsI with areas 169 cm 2 and 100 cm 2 , respectively. The detectors' sensitivity (for 10000 s at 3g/cm 3 with error bar of 3 σ) is about 10 -3 ∼ 10 -4 photons. cm -2 .s -1 at energies above 200 KeV. The detectors mounted on a stabilized platform observed the supernova for about 2 hours. The data are being analized for pulsations (≥ 0.5 ms) and gamma ray emission. Energy spectra and temporal analysis will be presented and discussed. (author) [pt

  9. A Decade of Solid Oxide Electrolysis Improvements at DTU Energy

    DEFF Research Database (Denmark)

    Hauch, Anne; Brodersen, Karen; Chen, Ming

    2017-01-01

    a short review of the R&D work on SOEC single cells conducted at DTU Energy from 2005 to 2015. The SOEC improvements have involved increasing the of the oxygen electrode performance, elimination of impurities in the feed streams, optimization of processing routes, and fuel electrode structure optimization....... All together, these improvements have led to a decrease in long-term degradation rate from ∼40 %/kh to ∼0.4 %/kh for steam electrolysis at -1 A/cm2, while the initial area specific resistance has been decreased from 0.44 Ωcm2 to 0.15 Ωcm2 at -0.5 A/cm2 and 750 °C....

  10. Surface sputtering in high-dose Fe ion implanted Si

    International Nuclear Information System (INIS)

    Ishimaru, Manabu

    2007-01-01

    Microstructures and elemental distributions in high-dose Fe ion implanted Si were characterized by means of transmission electron microscopy and Rutherford backscattering spectroscopy. Single crystalline Si(0 0 1) substrates were implanted at 350 deg. C with 120 keV Fe ions to fluences ranging from 0.1 x 10 17 to 4.0 x 10 17 /cm 2 . Extensive damage induced by ion implantation was observed inside the substrate below 1.0 x 10 17 /cm 2 , while a continuous iron silicide layer was formed at 4.0 x 10 17 /cm 2 . It was found that the spatial distribution of Fe projectiles drastically changes at the fluence between 1.0 x 10 17 and 4.0 x 10 17 /cm 2 due to surface sputtering during implantation

  11. Using Micromegas in ATLAS to Monitor the Luminosity

    CERN Document Server

    The ATLAS collaboration

    2013-01-01

    Five small prototype micromegas detectors were positioned in the ATLAS detector during LHC running at $\\sqrt{s} = 8\\, \\mathrm{TeV}$. A $9\\times 4.5\\, \\mathrm{cm^2}$ two-gap detector was placed in front of the electromagnetic calorimeter and four $9\\times 10\\, \\mathrm{cm^2}$ detectors on the ATLAS Small Wheels, the first station of the forward muon spectrometer. The one attached to the calorimeter was exposed to interaction rates of about $70\\,\\mathrm{kHz/cm^2}$ at ATLAS luminosity $\\mathcal{L}=5\\times 10^{33}\\,\\mathrm{cm^{-2}s^{-1}}$ two orders of magnitude higher than the rates in the Small Wheel. We compare the currents drawn by the detector installed in front of the electromagnetic calorimeter with the luminosity measurement in ATLAS experiment.

  12. Photochemical (PUVA) treatment of isolated rat islets

    International Nuclear Information System (INIS)

    Schmidt, S.; Wilke, B.; Kloeting, I.

    1984-01-01

    Isolated rat islets were irradiated with long-wave ultraviolet light alone or in combination with the photosensitizer 8-methoxypsoralen. The influence on specific beta cell functions was determined with the aim to find out experimental conditions which allow the use of such islets for transplantation. Short-term effects: Ultraviolet light affected [ 3 H]leucine incorporation into (pro)insulin (5 J/cm 2 : 53.8 %, 10 J/cm 2 : 41.0 % of the controls) and insulin release was slightly reduced. 8-methoxypsoralen enhanced the irradiation effect. Long-term effects: A restoration of irradiation-affected beta cell function was detected after 5 days of culture unless the dose exceeded 2 J/cm 2 (0.1 μM 8-methoxypsoralen) or 1 J/cm 2 (1 μM 8-methoxypsoralen). After functional restoration islets were used for transplantation experiments. (author)

  13. Swift and INTEGRAL observations of SAX J1747.0-2853

    DEFF Research Database (Denmark)

    Campana, S.; Chenevez, Jérôme; Kuulkers, E.

    2009-01-01

    on radius expansion Type I bursts). The 2-10 absorbed (unabsorbed) flux is 2.1(3.4) E-11 erg/cm^2/s. At 8 kpc this corresponds to 2E35 erg/s. Simultaneous observations with INTEGRAL between 11:42 and 15:24 UT confirm the faintness of the source, providing only upper limits: 8.E-11 erg/cm2/s (3-10 keV), 2.E......10-11 erg/cm^2/s (10-25 keV) and 1.E-10 erg/cm^2/s (15-40 keV) adopting a Crab like spectrum. Further observations and monitoring will assess if the source, after the bright Type I burst, is going to start a new outburst, remains in this quasi-persistent state or turns down to quiescence. We thank...

  14. Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

    KAUST Repository

    Zhitomirsky, David; Voznyy, Oleksandr; Levina, Larissa; Hoogland, Sjoerd; Kemp, Kyle W.; Ip, Alexander H.; Thon, Susanna M.; Sargent, Edward H.

    2014-01-01

    © 2014 Macmillan Publishers Limited. Colloidal quantum dots are attractive materials for efficient, low-cost and facile implementation of solution-processed optoelectronic devices. Despite impressive mobilities (1-30 cm2V-1 s-1) reported for new

  15. Ion induced segregation in gold nanostructured thin films on silicon

    International Nuclear Information System (INIS)

    Ghatak, J.; Satyam, P.V.

    2008-01-01

    We report a direct observation of segregation of gold atoms to the near surface regime due to 1.5 MeV Au 2+ ion impact on isolated gold nanostructures deposited on silicon. Irradiation at fluences of 6 x 10 13 , 1 x 10 14 and 5 x 10 14 ions cm -2 at a high beam flux of 6.3 x 10 12 ions cm -2 s -1 show a maximum transported distance of gold atoms into the silicon substrate to be 60, 45 and 23 nm, respectively. At a lower fluence (6 x 10 13 ions cm -2 ) transport has been found to be associated with the formation of gold silicide (Au 5 Si 2 ). At a high fluence value of 5 x 10 14 ions cm -2 , disassociation of gold silicide and out-diffusion lead to the segregation of gold to defect - rich surface and interface regions.

  16. Radiation doses to patients undergoing barium meal and barium enema examinations

    International Nuclear Information System (INIS)

    Delichas, M. G.; Hatziioannou, K.; Papanastassiou, E.; Albanopoulou, P.; Chatzi, E.; Sioundas, A.; Psarrakos, K.

    2004-01-01

    The radiation doses received by patients during 41 barium meal (BM) and 42 barium enema (BE) examinations in two Greek hospitals are presented. Radiation dose was measured in terms of the dose area product (DAP). The effective dose and doses to certain organs were estimated using the ODS-60 software. Mean total DAP values were found to be 25 ± 11 Gy cm 2 for BM and 60 ± 35 Gy cm 2 for BE examinations, whereas the estimated mean values of effective dose were 8.6 ± 4.0 and 24 ± 16 mSv respectively. DAP to effective dose conversion coefficients were estimated to be 0.34 mSv per Gy cm 2 for BM and 0.41 mSv per Gy cm 2 for BE. (authors)

  17. Seasonal variations of intensity of muons and electrons of decay in points of probe measurements of cosmic radiation in the atmosphere

    International Nuclear Information System (INIS)

    Kurguzova, A.I.; Charakhch'yan, T.N.

    1983-01-01

    Altitude-dependent intensities of muon and electron decay are calculated for the summer and winter seasons in the regions of Murmansk, Moscow, Alma-Ata and Mirnyj (the Antarctica). Values of the calculated temperature coefficients of muonf and electron decay for three levels (50, 500 and 1000 g/cm 2 ) are given. Seasonal variations of the muone and electron intensities are practically the same for all the points at depths X > 300 g/cm 2 (approximately 5% for muons and approximately 1% for electrons); at depths X 2 in Mirnyj the variations are considerably higher than in other points. Seasonal variations of the cosmic ray intensity on the surface of the Earth make up approximately 4%, in the low atmosphere (X=500 g/cm 2 ) they make up approximately 2%. In Mirnyj the seasonal variations of cosmic rays in the stratosphere (X=50 g/cm 2 ) also make up approximately 2%

  18. High current density M-type cathodes for vacuum electron devices

    International Nuclear Information System (INIS)

    Li Ji; Yu Zhiqiang; Shao Wensheng; Zhang Ke; Gao Yujuan; Yuan Haiqing; Wang Hui; Huang Kaizhi; Chen Qilue; Yan Suqiu; Cai Shaolun

    2005-01-01

    We investigated high current density emission capabilities of M-type cathodes used for vacuum electron devices (VEDs). The experimental results of emission and lifetime evaluating in both close-spaced diode structure and electron gun testing vehicles are given. Emission current densities measured in the diode structure at 1020 deg. C Br in the CW mode were above 10 A/cm 2 ; while in electron gun testing vehicles, emission current densities were above 8 A/cm 2 in CW mode and above 32 A/cm 2 in pulsed mode, respectively. The current density above 94 A/cm 2 has been acquired in no. 0306 electron gun vehicle while the practical temperature is 1060 deg. C Br . For a comparison some of the data from I-scandate cathodes are presented. Finally, several application examples in practical travelling wave tubes (TWTs) and multi beam klystrons (MBKs) are also reported

  19. Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

    KAUST Repository

    Mei, Jianguo

    2011-12-21

    We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1), was obtained from solution-processed thin-film transistors, one of the highest mobilities reported to date. In contrast, the reference polymer with a branched alkyl side chain gave an average hole mobility of 0.30 cm 2 V -1 s -1 and a maximum mobility of 0.57 cm 2 V -1 s -1. This is largely explained by the polymer packing: our new polymer exhibited a π-π stacking distance of 3.58 Å, while the reference polymer showed a distance of 3.76 Å. © 2011 American Chemical Society.

  20. Electrified Liquid Jets from Nanostructured Surfaces for Phase Change Heat Transfer Enhancement

    Data.gov (United States)

    National Aeronautics and Space Administration — The need exists to dissipate up to 1kW/cm2 with minimum cooling power overhead and a minimum weight. Using micro and nanostructures on hot surfaces recently emerged...

  1. RF-source development for ITER: Large area H- beam extraction, modifications for long pulse operation and design of a half size ITER source

    International Nuclear Information System (INIS)

    Kraus, W.; Heinemann, B.; Falter, H.D.; Franzen, P.; Speth, E.; Entscheva, A.; Fantz, U.; Franke, T.; Holtum, D.; Martens, Ch.; McNeely, P.; Riedl, R.; Wilhelm, R.

    2005-01-01

    With an extraction area of 152 cm 2 a calorimetrically measured H - current density of 19.3 mA/cm 2 has been achieved at 0.45 Pa with 90 kW RF power. With 306 cm 2 the electrically measured H - current has reached up to 9.7 A corresponding to 32 mA/cm 2 at 100 kW. The current on the calorimeter is limited by the extraction system. Down to 0.2 Pa only a weak dependence on the source pressure has been observed. The test bed will be upgraded to demonstrate cw operation with deuterium. Based on the tested prototype a half size ITER RF-source of 80 cm x 90 cm with 360 kW RF power has been designed

  2. Channeling study of laser-induced defect generation in InP and InAs

    International Nuclear Information System (INIS)

    Burdel', K.K.; Kashkarov, P.K.; Timoshenko, V.Yu.; Chechenin, N.G.

    1992-01-01

    Damage production in InP and InAs single crystals induced by a ruby-laser pulse irradiation with τ p =20 ms in the energy density region W=0.05-1.0 J/cm 2 is studied by the channeling and Rutherford backscattering techniques. The defect generation threshold was determined to be equal to 0.2 J/cm 2 and 0.55 J/cm 2 for InP and InAs crystals, respectively. Stoichiometric defects in InP crystals were observed at W>=0.5 J/cm 2 . The temperature fields in InP and InAs under laser irradiation were calculated. The experimental observations are considered as a result of a selective evaporation of the components from the melt

  3. Anti-tumor activities of a novel chlorin derivative for photodynamic therapy in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Li-Jun Zhang

    2015-01-01

    Full Text Available In this study, a novel photosensitizer meso-tetra (3-pyrrolidinomethyl-4-methoxyphenyl chlorin (TPMC was reported. It displays a characteristic long wavelength absorption peak at 656 nm and it shows a singlet oxygen quantum yield of 0.48. After light irradiation with 650 nm laser, it can kill Eca-109 and SMMC-7721 cells in vitro (25 mW/cm2, 1.2 to 3.6 J/cm2 and destroy Eca-109 tumor in nude mice (50 mW/cm2, 90 J/cm2. It has the perspective to be developed as a new anti-tumor drug in photodynamic therapy (PDT photodiagnosis, and deserves further investigation.

  4. Periodic patterning of silicon by direct nanosecond laser interference ablation

    International Nuclear Information System (INIS)

    Tavera, T.; Pérez, N.; Rodríguez, A.; Yurrita, P.; Olaizola, S.M.; Castaño, E.

    2011-01-01

    The production of periodic structures in silicon wafers by four-beam is presented. Because laser interference ablation is a single-step and cost-effective process, there is a great technological interest in the fabrication of these structures for their use as antireflection surfaces. Three different laser fluences are used to modify the silicon surface (0.8 J cm -2 , 1.3 J cm -2 , 2.0 J cm -2 ) creating bumps in the rim of the irradiated area. Laser induced periodic surface structures (LIPSS), in particular micro and nano-ripples, are also observed. Measurements of the reflectivity show a decrease in the reflectance for the samples processed with a laser fluence of 2.0 J cm -2 , probably caused by the appearance of the nano-ripples in the structured area, while bumps start to deteriorate.

  5. Covalently cross-linked polyetheretherketone proton exchange membrane for DMFC

    CSIR Research Space (South Africa)

    Luo, H

    2009-05-01

    Full Text Available -7 cm2/s) and good electrochemical stability. The results suggested that cross-linked polyetheretherketone membrane is particularly promising to be used as proton exchange membrane for the direct methanol fuel cell application....

  6. Design and performance of a one square meter proportional counter system for hard X-ray astronomy

    International Nuclear Information System (INIS)

    Bazzano, A.; Boccaccini, L.; La Padula, C.D.; Mastropietro, M.; Patriarca, R.; Polcaro, F.; Ubertini, P.

    1983-01-01

    A versatile balloon borne hard X-ray experiment with a very large area (approx.= 1.1 m 2 ) and high spectral resolution has been developed for the study of the hard X-ray sources in the energy range 20-180 keV. The telescope consists of four multiwire proportional chambers (MWPC) that have a geometrical sensitive area of 2700 cm 2 each. The detector system has a sensitivity of approx.= 10 -5 photons cm -2 s -1 keV -1 during a typical balloon observation. A background rate of approx.= 3 x 10 -4 counts cm -2 s -1 keV -1 was observed in the operative energy range at 2.4 gm/cm 2 ceiling altitude and geographic latitude of 38 0 N. The design details, fabrication and flight performance of the instrument are briefly discussed with reference to the effectiveness of background reduction and other test parameters. (orig.)

  7. Development of Epitaxial GaN Films for RF Communications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The primary objective of this SBIR is to develop epitaxial GaN films with threading dislocation density less than 10^6 cm^-2. We propose an innovative approach...

  8. LAT Daily Lightcurve FITS Files

    Data.gov (United States)

    National Aeronautics and Space Administration — LAT data between 100 MeV and 10 GeV filtered for solar counts in 1-minute time bins, no energy binning, using light-bucket method. Contains exposure (cm^2 s)...

  9. High energy proton irradiation effects on SiC Schottky rectifiers

    International Nuclear Information System (INIS)

    Nigam, S.; Kim, Jihyun; Ren, F.; Chung, G.Y.; MacMillan, M.F.; Dwivedi, R.; Fogarty, T.N.; Wilkins, R.; Allums, K.K.; Abernathy, C.R.; Pearton, S.J.; Williams, J.R.

    2002-01-01

    4H-SiC Schottky rectifiers with dielectric overlap edge termination were exposed to 40 MeV protons at fluences from 5x10 7 -5x10 9 cm -2 . The reverse breakdown voltage decreased from ∼500 V in unirradiated devices to ∼-450 V after the highest proton dose. The reverse leakage current at -250 V was approximately doubled under these conditions. The forward current at -2 V decreased by ∼1% (fluence of 5x10 7 cm -2 ) to ∼42% (fluence of 5x10 9 cm -2 ), while the current at lower biases was increased due to the introduction of defect centers. The ideality factor, on-state resistance, and forward turn-on voltage showed modest increases for fluences of ≤5x10 8 cm -2 , but were more strongly affected (increase of 40%-75%) at the highest dose employed

  10. Superior radiation tolerance of thin epitaxial silicon detectors

    CERN Document Server

    Kramberger, G; Fretwurst, E; Honniger, F; Lindström, G; Pintilie, I; Röder, R; Schramm, A; Stahl, J

    2003-01-01

    For the LHC upgrade (fluences up to 10**1**6 p/cm**2) epi-Si devices are shown to be a viable solution. No type inversion was measured up to 1.3 multiplied by 10**1**524 GeV/c protons/cm**2 and the charge collection efficiency (CCE) remained close to 100%. For reactor neutrons CCE was measured to be 60% at 8 multiplied by 10**1**5 n/cm **2. Annealing measurements have shown that only moderate cooling during beam off periods would be necessary. As a tentative explanation for the superior quality of these devices, we assume that radiation-induced donor generation leads to compensation effects of deep acceptors. In the future, we will extend the experiments to fluences up to 10**1**6 p/cm**2 and use also different variants of the epi-Si material and device geometry.

  11. The Influence Of Temperature And Pressure On AP600 Pressure Vessel Analysis By Two Dimensional Finite Element Method

    International Nuclear Information System (INIS)

    Utaya

    1996-01-01

    Pressure vessel is an important part of nuclear power plan, and its function is as pressure boundary of cooling water and reactor core. The pressure vessel wall will get pressure and thermal stress. The pressure and thermal stress analysis at the simplified AP600 wall was done. The analysis is carried out by finite method, and then solved by computer. The analysis result show, that the pressure will give the maximum stress at the inner wall (1837 kg/cm 2 ) and decreased to the outer wall (1685 kg/cm 2 ). The temperature will decreased the stress at the inner wall (1769 kg/cm 2 ) and increased the stress at the outer wall (1749 kg/cm 2 )

  12. Studies on effects of salicylic acid and thiourea on biochemical ...

    African Journals Online (AJOL)

    Henrik

    2012-08-09

    Aug 9, 2012 ... nitrogenous compounds, antioxidant enzymes, and mineral nutrition ... the form of Ammonium nitrate (33.5% N), calcium superphosphate ... Flag leaf area: The leaf area (cm2) was determined by the method described in ...

  13. MECHANICAL CHARACTERIZATION AND SHRINKAGE OF Sclerolobium paniculatum Vogel WOOD IN A HOMOGENEOUS PLANTING UNDER DIFFERENT LEVELS OF FERTILIZATION

    Directory of Open Access Journals (Sweden)

    Joselito Bonifácio Oliveira

    2010-08-01

    Full Text Available The purposa of this work was to study the influence of fertilization on wood quality of Sclerolobium paniculatum Vogel. A homogeneous planting trial, under different levels of liming and phosphorus, was established by Embrapa-Cerrados 18 years ago in Planaltina, Distrito Federal, Brazil, tropical wood savanna region. Mechanical tests conducted were static bending, parallel compression to grain, shear strength and shrinkage. No significant differences were observed for mechanical properties or for shrinkage, which presented: ¦b = 650kg/cm2, E = 59.877kg/cm2, ¦c = 296kg/cm2 e ¦n = 131kg/cm2. Control treatment showed highest values for shear strength and compression parallel to grain. Too many branches in all trees and also too many knots in lumber were observed. Pruning is recommended for homogeneous planting of Sclerolobium paniculatum to avoid knots in order to be produced wood of superior quality.

  14. Measurements of RF Radiation in the Vicinity of FM and TV Broadcasting Stations

    Directory of Open Access Journals (Sweden)

    Abdulaziz S. Al-Ruwais

    2001-12-01

    Full Text Available This paper provides measurements of power density around an FM and VHF-TV broadcasting station and its variation with distance.  The maximum measured value was about 2.4 mW/cm2 at a height of 2 meters above ground level while the average value was fluctuating around 1 mW/cm2.  It was found that the measured power density increases with height above ground and it reaches about 3.5 mW/cm2 at a height of about 15 meters at a location of about 400 meters from the station.  At a nearer distance of 185 meters from the tower another measurement was taken at a height of 18 meters, the power density increased to 41 mW/cm2.

  15. Burnout power in once-through tubular steam generators

    International Nuclear Information System (INIS)

    Campolunghi, F.; Cumo, M.; Ferrari, G.; Leo, R.; Vaccaro, G.

    1974-01-01

    The present experimental research provides experimental data in a design field where existing burnout correlations are usually extrapolated outside their validity range. Low surface heat fluxes and very long geometries typical of L.M.F.B.R. sodium heated steam generators require full scale water tests. 218 burnout qualities at pressures ranging from 60 to 160 kg/cm 2 and specific mass flowrates from 110 to 260 g/cm 2 s were measured and tested against the most known burnout correlations. Physically it appears that burnout quality is substantially independent from the flowrate, while a sharp subdivision with pressure suggests that for 60 less than p less than 90 kg/cm 2 and 110 less than p less than 160 kg/cm 2 two different burnout mechanisms may set up. (U.S.)

  16. Ocean circulation code on machine connection

    International Nuclear Information System (INIS)

    Vitart, F.

    1993-01-01

    This work is part of a development of a global climate model based on a coupling between an ocean model and an atmosphere model. The objective was to develop this global model on a massively parallel machine (CM2). The author presents the OPA7 code (equations, boundary conditions, equation system resolution) and parallelization on the CM2 machine. CM2 data structure is briefly evoked, and two tests are reported (on a flat bottom basin, and a topography with eight islands). The author then gives an overview of studies aimed at improving the ocean circulation code: use of a new state equation, use of a formulation of surface pressure, use of a new mesh. He reports the study of the use of multi-block domains on CM2 through advection tests, and two-block tests

  17. Hydrogen Solubility in Pr-doped and Un-doped YSZ for One Chamber Fuel Cell

    DEFF Research Database (Denmark)

    Bay, Lasse; Horita, T.; Sakai, N.

    1998-01-01

    SIMS analysis. Doping of Pr in the YSZ resulted in a higher intensity of the D ion, which indicated that hydrogen solubility was raised by the doping. The solubility of hydrogen in the electrolyte may affect the performance of one chamber fuel cells. (C) 1998 Elsevier Science B.V. All rights reserved.......Yttria-stabilised zirconia electrolytes (YSZ and Pr-doped YSZ) and yttria-doped strontium cerate (SYC) were tested in a one chamber fuel cell fed with a mixture of methane and air at 1223 K. The obtained performances were 4 mW cm(-2), 3 mW cm(-2), 2.5 mW cm(-2), and 0.15 mW cm(-2) for SYC, 1.8 mol...

  18. PLOIDY STATUS OF Dioscorea alata L. AND ITS RELATIONSHIP ...

    African Journals Online (AJOL)

    AISA

    Flowering clones were found to be not susceptible to Anthracnose. Key-words : Anthracnose .... plants for flow cytometry analysis. About. 1 cm2 of leaf ..... And Crop Evolution 46 : 19 - 27. Hamon P. J. ... classification of Dioscorea alata. Tropical.

  19. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 3 ... F/cm2 for the high-frequency semicircle, while for the second semicircle the interface ... School of Urban Rail Transportation, Soochow University, Suzhou 215006, China ...

  20. Electrically Injected Polariton Lasing from a GaAs-Based Microcavity under Magnetic Field

    KAUST Repository

    Bhattacharya, Pallab; Das, Ayan; Jankowski, Marc; Bhowmick, Sishir; Lee, Chi-Sen; Jahangir, Shafat

    2012-01-01

    Suppression of relaxation bottleneck and subsequent polariton lasing is observed in a GaAs-based microcavity under the application of a magnetic field. The threshold injection current density is 0.32 A/cm2 at 7 Tesla.

  1. High Efficiency Microchannel Diamond Heat Sinks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — While absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (~50 W/cm2 in...

  2. Alpha particles emitted from the surface of granite, clay, and its fired products, 1

    International Nuclear Information System (INIS)

    Aratani, Michi; Otsuka, Hideko

    1975-01-01

    As a part of an investigation on ''the effect of long-time irradiation from a trace amount of radioisotopes'', the emitting rate of alpha particles per unit surface area (apparent) coming from natural alpha-particle emitters has been measured. The samples measured were granite and its weathered product; clay, especially potter's clay, and its fired product; pottery ware. The values obtained were 39.1 +-0.9--0.73+-0.08 cpm/100 cm 2 in granite, 16.8+-0.4--6.4+-0.2 cpm/100cm 2 in potter's clay, and 1.36+-0.04--0.82+-0.04 cpm/100cm 2 in pottery ware on substrate, and 1.33+-0.05--0.32+-0.02 cpm/100cm 2 on glazer. (auth.)

  3. Heat transfer from aluminum to He II: application to superconductive magnetic energy storage

    International Nuclear Information System (INIS)

    Van Sciver, S.W.; Boom, R.W.

    1979-01-01

    Heat transfer problems associated with large scale Superconductive Magnetic Energy Storage (SMES) are unique due to the proposed size of a unit. The Wisconsin design consists of a cryogenically stable magnet cooled with He II at 1.8 K. The special properties of He II (T 2 at 1.91 K and a recovery at 0.7 W/cm 2 . The advantages of operating the magnet under subcooled conditions are exemplified by improved heat transfer. The maximum at 1.89 K and 1.3 atm pressure is 2.3 W/cm 2 with recovery enhanced to 1.9 W/cm 2 . A conservative maximum heat flux of 0.5 W/cm 2 with an associated temperature difference of 0.5 K has been chosen for design. Elements of the experimental study as well as the design will be discussed

  4. A piecewise-focused high DQE detector for MV imaging.

    Science.gov (United States)

    Star-Lack, Josh; Shedlock, Daniel; Swahn, Dennis; Humber, Dave; Wang, Adam; Hirsh, Hayley; Zentai, George; Sawkey, Daren; Kruger, Isaac; Sun, Mingshan; Abel, Eric; Virshup, Gary; Shin, Mihye; Fahrig, Rebecca

    2015-09-01

    Electronic portal imagers (EPIDs) with high detective quantum efficiencies (DQEs) are sought to facilitate the use of the megavoltage (MV) radiotherapy treatment beam for image guidance. Potential advantages include high quality (treatment) beam's eye view imaging, and improved cone-beam computed tomography (CBCT) generating images with more accurate electron density maps with immunity to metal artifacts. One approach to increasing detector sensitivity is to couple a thick pixelated scintillator array to an active matrix flat panel imager (AMFPI) incorporating amorphous silicon thin film electronics. Cadmium tungstate (CWO) has many desirable scintillation properties including good light output, a high index of refraction, high optical transparency, and reasonable cost. However, due to the 0 1 0 cleave plane inherent in its crystalline structure, the difficulty of cutting and polishing CWO has, in part, limited its study relative to other scintillators such as cesium iodide and bismuth germanate (BGO). The goal of this work was to build and test a focused large-area pixelated "strip" CWO detector. A 361 × 52 mm scintillator assembly that contained a total of 28 072 pixels was constructed. The assembly comprised seven subarrays, each 15 mm thick. Six of the subarrays were fabricated from CWO with a pixel pitch of 0.784 mm, while one array was constructed from BGO for comparison. Focusing was achieved by coupling the arrays to the Varian AS1000 AMFPI through a piecewise linear arc-shaped fiber optic plate. Simulation and experimental studies of modulation transfer function (MTF) and DQE were undertaken using a 6 MV beam, and comparisons were made between the performance of the pixelated strip assembly and the most common EPID configuration comprising a 1 mm-thick copper build-up plate attached to a 133 mg/cm(2) gadolinium oxysulfide scintillator screen (Cu-GOS). Projection radiographs and CBCT images of phantoms were acquired. The work also introduces the use of a

  5. Synthesis and Applications of Large Area Graphene-Based Electrode Systems

    Science.gov (United States)

    Paul, Rajat Kanti

    limit of detections of 15 ppb (parts-per billion) and 160 ppb, significantly lower than Occupational Safety and Health Administration (OSHA) permissible exposure limits of 5 ppm (NO2) and 50 ppm (NH3), respectively. The demonstrated studies on the sensing properties of graphene nanomesh would essentially lead further improvement of it's sensitivity and selectivity as a potential sensor material. Furthermore, a three-dimensional (3D) carbon electrode in the form of vertically aligned carbon nanotubes (CNTs) on a graphene floor is applied as a supporting electrode for platinum (Pt) nanoflowers electrocatalysts in methanol oxidation as well as in nonenzymatic sensing of blood glucose. Experimental results demonstrate an enhanced efficiency of the 3D graphene-carbon nanotubes hybrid film, as catalyst support, for methanol oxidation with regard to electroactive surface area, forward anodic peak current density, onset oxidation potential, diffusion efficiency and the ratio of forward to backward anodic peak current density (If/Ib). Also, the developed nonenzymatic 3D carbon hybrid sensor responded linearly to the physiological glucose concentration ranging from 1 to 7 mM (R2 = 0.978) with a sensitivity of 11.06 muA mM-1cm-2.

  6. Development of novel imaging probe for optical/acoustic radiation imaging (OARI).

    Science.gov (United States)

    Ejofodomi, O'tega A; Zderic, Vesna; Zara, Jason M

    2013-11-01

    Optical/acoustic radiation imaging (OARI) is a novel imaging modality being developed to interrogate the optical and mechanical properties of soft tissues. OARI uses acoustic radiation force to generate displacement in soft tissue. Optical images before and after the application of the force are used to generate displacement maps that provide information about the mechanical properties of the tissue under interrogation. Since the images are optical images, they also represent the optical properties of the tissue as well. In this paper, the authors present the first imaging probe that uses acoustic radiation force in conjunction with optical coherence tomography (OCT) to provide information about the optical and mechanical properties of tissues to assist in the diagnosis and staging of epithelial cancers, and in particular bladder cancer. The OARI prototype probe consisted of an OCT probe encased in a plastic sheath, a miniaturized transducer glued to a plastic holder, both of which were encased in a 10 cm stainless steel tube with an inner diameter of 10 mm. The transducer delivered an acoustic intensity of 18 W/cm(2) and the OCT probe had a spatial resolution of approximately 10-20 μm. The tube was filled with deionized water for acoustic coupling and covered by a low density polyethylene cap. The OARI probe was characterized and tested on bladder wall phantoms. The phantoms possessed Young's moduli ranging from 10.2 to 12 kPa, mass density of 1.05 g/cm(3), acoustic attenuation coefficient of 0.66 dB/cm MHz, speed of sound of 1591 m/s, and optical scattering coefficient of 1.80 mm(-1). Finite element model (FEM) theoretical simulations were performed to assess the performance of the OARI probe. The authors obtained displacements of 9.4, 8.7, and 3.4 μm for the 3%, 4%, and 5% bladder wall phantoms, respectively. This shows that the probe is capable of generating optical images, and also has the ability to generate and track displacements in tissue. This will

  7. Optical properties of bovine muscle tissue in vitro; a comparison of methods

    International Nuclear Information System (INIS)

    Zijp, Jaap R.; Bosch, Jaap J. ten

    1998-01-01

    We measured the optical properties of muscular tissue using several methods. Collimated transmission measurements of thin slabs showed spatial anisotropy of the scattering processes. Surface roughness of the sample disables the calculation of the extinction coefficient from these measurements. From angular intensity measurements we found a scattering asymmetry parameter g 0.96. In fresh samples the optical diffusion constant D depends on the orientation with respect to the longitudinal direction of the muscular cells. From the D values we calculated s' perpendicular to the longitudinal direction as 0.19 mm -1 (at 543 nm), 0.39 mm -1 (at 594 nm) and 0.59 mm -1 (at 632 nm). The values for D which we measured from samples that were frozen and thawed did not show dependence on orientation. From spectral dependent reflectance measurements we found an oxygenation degree of 0.61 and a reduced scattering coefficient s'=0.85mm -1 around 560 nm. (author)

  8. Author Details

    African Journals Online (AJOL)

    Journal Home > Advanced Search > Author Details ... Design and Implementation of an M/M/1 Queuing Model Algorithm and its Applicability in ... Vehicle Identification Technology to Intercept Small Arms and Ammunition on Nigeria Roads

  9. 46 CFR 160.021-3 - Materials, workmanship, construction and performance requirements.

    Science.gov (United States)

    2010-10-01

    ... affect uniformity of its burning characteristics. The cap shall have a lap fit of not less than 25 mm (1... a water-resistant coating on the signal plus packaging in a sealed plastic waterproof bag...

  10. Effects of microwave radiation on peripheral lymphocyte subpopulations in rats

    Directory of Open Access Journals (Sweden)

    Jin-ling YIN

    2011-10-01

    Full Text Available Objective To investigate the effects and mechanisms of microwave radiation on peripheral lymphocyte subpopulations in Wistar rats.Methods A total of 100 Wistar rats(180-220g were exposed to microwave with different average power densities of 5,10,30 and 60 mW/cm2,and sham exposure of 0mW/cm2 was performed in a control group at the same time.At day 1,7,14 and 28 after microwave irradiation,the changes in peripheral CD3+,CD4+,CD8+ T cells,ratio of CD4+/CD8+ and CD45RA+ B lymphocyte in rats were analyzed by flow cytometry(FCM.Results The CD3+ T cells decreased significantly in 10-30mW/cm2 groups at day 7 and in 5-30 mW/cm2 groups at day 14 after radiation as compared with control group(P < 0.05,and CD4+ T cells decreased significantly in 10mW/cm2 group at day 14 after radiation as compared with control group(P < 0.01.From day 1 to day 14 after radiation,CD8+ T cells showed a reduction in number in all irradiated groups when compared with the control,but statistical significance was only found in the 30mW/cm2 group(P < 0.05.The CD4+/CD8+ ratio increased in 5mW/cm2 group on day 1,while decreased significantly in 5-30mW/cm2 groups on day 14 after radiation as compared with control group(P < 0.05.After microwave exposure,however,CD45RA+ B cells in 30mW/cm2 group at day 1 and in 30-60mW/cm2 groups at day 14 after radiation increased significantly in a dose-dependent manner.Conclusion A definite dosage of microwave radiation,ranging from 5-60mW/cm2,may induce changes in subpopulations of peripheral lymphocytes and cause acute immune function impairment in rats.

  11. Heating of aluminum by SPR-III burst

    International Nuclear Information System (INIS)

    Judd, S.V.

    1987-01-01

    Real time temperature measurements were made on an aluminum cylinder exposed to radiation bursts at SPR-III at neutron levels from 10 11 cm -2 to 4.5 x 10 14 cm -2 . Precision thermistors and high speed A/D converters were used to measure temperature with .0025 degree C resolution at 20ms intervals following the burst. Temperature data is presented as a function of neutron fluence

  12. Angular distributions and total yield of laser ablated silver

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Nordskov, A.; Schou, Jørgen

    1997-01-01

    The angular distribution of laser ablated silver has been measured in situ with a newly constructed setup with an array of microbalances. The distribution is strongly peaked in the forward direction corresponding to cospθ, where p varies between 5 and 9 for laser fluences from 2 to 7 J/cm2 at 355...... nm for a beam spot of 0.015 cm2. The total deposited yield is of the order 1015 Ag-atoms per pulse....

  13. Effects of Carbopol® 934 proportion on nanoemulsion gel for topical and transdermal drug delivery: a skin permeation study.

    Science.gov (United States)

    Zheng, Yin; Ouyang, Wu-Qing; Wei, Yun-Peng; Syed, Shahid Faraz; Hao, Chao-Shuang; Wang, Bo-Zhen; Shang, Yan-Hong

    Nanoemulsions (NEs) are used as transdermal drug delivery systems for systematic therapeutic purposes. We hypothesized that the skin permeation profile of an NE could be modulated by incorporating it into a hydrogel containing differing proportions of thickening agent. The objectives of this study were as follows: 1) to determine the stability and skin irritability of NE gels (NGs) containing 1%, 2%, and 3% (w/w) Carbopol ® 934 (CP934) (termed NG1, NG2, and NG3, respectively); 2) to compare the skin permeation profiles and drug deposition patterns of the NGs; and 3) to visualize the drug delivery routes of the NGs. Terbinafine and citral were incorporated into the NGs as model drugs. Ex vivo skin permeation tests indicated that the percutaneous flux rates of terbinafine decreased in the order NE (215 μg/cm 2 ) > NG1 (213 μg/cm 2 ) > NG2 (123 μg/cm 2 ) > NG3 (74.3 μg/cm 2 ). The flux rates of citral decreased in the order NE (1,026 μg/cm 2 ) > NG1 (1,021 μg/cm 2 ) > NG2 (541 μg/cm 2 ) > NG3 (353 μg/cm 2 ). The NGs accumulated greater amounts of the drugs in the stratum corneum and less in the epidermis/dermis than did the NE ( P drug delivery routes from skin appendages to intercellular paths. Histological images suggested that perturbations to the skin structure, specifically the size of the epidermal intercellular spaces and the separation distance of dermal collagen bundles, could be significantly minimized by increasing the proportion of CP934. These results suggest that adjustments of the CP934 proportions can be used to modulate the skin permeation profiles of NGs for specific therapeutic purposes.

  14. Laser ablation of dental calculus at 400 nm using a Ti:sapphire laser

    Science.gov (United States)

    Schoenly, Joshua E.; Seka, Wolf; Rechmann, Peter

    2009-02-01

    A Nd:YAG laser-pumped, frequency-doubled Ti:sapphire laser is used for selective ablation of calculus. The laser provides calculus removal. This is in stark contrast with tightly focused Gaussian beams that are energetically inefficient and lead to irreproducible results. Calculus is well ablated at high fluences >=2J/cm2 stalling occurs below this fluence because of photobleaching. Healthy hard tissue is not removed at fluences <=3 J/cm2.

  15. Isolasi mikroba endofitik dari tanaman obat sambung nyawa (Gynura procumbens dan analisis potensinya sebagai antimikroba

    Directory of Open Access Journals (Sweden)

    Rumella Simarmata

    2012-02-01

    Full Text Available Sambung nyawa (Gynura procumbens has many beneficial effects to human health, such as decreasing blood pressure, maintaining blood sugar level (hypoglycaemic, decreasing cholesterol, a remedy for kidney trouble, antibacterial and lessen the inflamation (antiinflamation. This research was undertaken to discover the potency of endophytic microbes from sambung nyawa as antimicrobial agents. The purpose of this research was to screen the endophytic bacteria and the endophytic fungi having antimicrobial activity, which were isolated from stems, leaves, roots and fruits of medical plants, sambung nyawa. The antimicrobial activity was determined by measuring the growth inhibition of pathogenic microbes i.e Candida albicans, Escherichia coli, Pseudomonas sp. and Bacillus subtilis. A total of 38 isolates of bacteria and 15 isolates of fungi were obtained from sambung nyawa. Analysis demonstrated that, 45% isolates of bacteria and 20% isolates of fungi exhibited inhibitory activity. Antimicrobial activity was found in 21% of the isolates that inhibited the growth of C. albicans, E. coli, Pseudomonas sp., and B. subtilis, whereas 24% of isolates had activity only against B. subtilis. Isolate of endophytic bacteria USN 1.1 and USN 2.3 showed the most significant of inhibition zone. The Inhibition zone of the isolate USN 1.1 to C. albicans, E. coli, Pseudomonas sp, and B. subtilis were 2.318 cm2, 0.969 cm2, 0.796 cm2, and 0.381 cm2, respectively. The Inhibition zone of the isolate USN 2.3 to C. albicans, E. coli, Pseudomonas sp., and B. subtilis were 3.01 cm2, 0.519 cm2, 0.588 cm2 and 0.83 cm2, respectively. These results indicated that endophytic bacteria and endophytic fungi could be a promising source for antimicrobial agents.

  16. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

    Science.gov (United States)

    Brooks, Emily K; Tobias, Menachem E; Yang, Shuying; Bone, Lawrence B; Ehrensberger, Mark T

    2016-02-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin  = 2.64 e4 Ω/cm(2) , Rout  = 140 Ω/cm(2) ) compared to 21 days (Rin  = 3.60 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin  = 1.88 e5 Ω/cm(2) , Rout  = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin  = 2.99 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. © 2015 Wiley Periodicals, Inc.

  17. Wearable Fabrics with Self-Branched Bimetallic Layered Double Hydroxide Coaxial Nanostructures for Hybrid Supercapacitors.

    Science.gov (United States)

    Nagaraju, Goli; Chandra Sekhar, S; Krishna Bharat, L; Yu, Jae Su

    2017-11-28

    We report a flexible battery-type electrode based on binder-free nickel cobalt layered double hydroxide nanosheets adhered to nickel cobalt layered double hydroxide nanoflake arrays on nickel fabric (NC LDH NFAs@NSs/Ni fabric) using facile and eco-friendly synthesis methods. Herein, we utilized discarded polyester fabric as a cost-effective substrate for in situ electroless deposition of Ni, which exhibited good flexibility, light weight, and high conductivity. Subsequently, the vertically aligned NC LDH NFAs were grown on Ni fabric by means of a hot-air oven-based method, and fluffy-like NC LDH NS branches are further decorated on NC LDH NFAs by a simple electrochemical deposition method. The as-prepared core-shell-like nanoarchitectures improve the specific surface area and electrochemical activity, which provides the ideal pathways for electrolyte diffusion and charge transportation. When the electrochemical performance was tested in 1 M KOH aqueous solution, the core-shell-like NC LDH NFAs@NSs/Ni fabric electrode liberated a maximum areal capacity of 536.96 μAh/cm 2 at a current density of 2 mA/cm 2 and excellent rate capability of 78.3% at 30 mA/cm 2 (420.5 μAh/cm 2 ) with a good cycling stability. Moreover, a fabric-based hybrid supercapacitor (SC) was assembled, which achieves a stable operational potential window of 1.6 V, a large areal capacitance of 1147.23 mF/cm 2 at 3 mA/cm 2 , and a high energy density of 0.392 mWh/cm 2 at a power density of 2.353 mW/cm 2 . Utilizing such high energy storage abilities and flexible properties, the fabricated hybrid SC operated the wearable digital watch and electric motor fan for real-time applications.

  18. Effects of Nonlinear Absorption in BK7 and Color Glasses at 355 nm

    International Nuclear Information System (INIS)

    Adams, J J; McCarville, T; Bruere, J; McElroy, J; Peterson, J

    2003-01-01

    We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217 ± 10% cm -1 , 1.7 ± 10% cm -1 , and 0.82 ± 10% cm -1 , respectively, two-photon absorption cross-sections of 0.025 ± 20% cm/GW, 0.035 ± 20% cm/GW, and 0.047 ± 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10 -18 ± 20% cm 2 , 2.8 x 10 -16 ± 20% cm 2 , and 5 x 10 -17 ± 20% cm 2 , respectively, and solarization coefficients of 8.5 x 10 -20 ± 20% cm 2 , 2.5 x 10 -18 ± 20% cm 2 , and 1.3 x 10 -19 ± 20% cm 2 , respectively. For our application, nonlinear effects in 10-cm of BK7 are small ((le) 2%) for 355-nm fluences 2 for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm 2 . In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of 0.8 J/cm 2 . For 0.5-cm of UG1 absorbing glass the non-linear absorption has a similar effect as that from 10-cm of BK7 on the pulse shape; however, the effects in UG11 are much smaller

  19. Destruction of fast H(2S) atoms in collisions with neon, krypton, xenon, and molecular hydrogen

    International Nuclear Information System (INIS)

    Roussel, F.; Pradel, P.; Spiess, G.

    1977-01-01

    Measurements are reported for the total quenching of metastable hydrogen atoms by neon, krypton, xenon, and molecular hydrogen, in the energy range 0.052--3 keV. The cross sections are found to be on the order of 5 x 10 -15 cm 2 at the lowest energies, and decrease to approximately 2 x 10 -15 cm 2 at the highest energies. The data at low energy are analyzed using a simple theoretical model

  20. Performance of Electrolyte Supported Solid Oxide Fuel Cells with STN Anodes

    DEFF Research Database (Denmark)

    Veltzé, Sune; Reddy Sudireddy, Bhaskar; Jørgensen, Peter Stanley

    2013-01-01

    In order to replace the state of the art Ni-cermet as SOFC anode, electrolyte supported cells comprising CGO/Ni infiltrated Nbdoped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 C. Further tests under...

  1. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    ... showed that compressive strength and leaching behaviour are better when the ferric strength was < 5 N. The diffusion coefficient of Cs from the cement matrix was found to be in the range 2.4 × 10-5 cm2/day and 5.9 × 10-5 cm2/day with ferric solutions of strength in the range 0.5–3 N. When bentonite and vermiculite were ...

  2. Potent limonoid insect antifeedant from Melia azedarach.

    Science.gov (United States)

    Carpinella, Cecilia; Ferrayoli, Carlos; Valladares, Graciela; Defago, Maria; Palacios, Sara

    2002-08-01

    Systematic fractionation of a fruit extract from Argentine Melia azedarach L., which was monitored by an insect antifeedant bioassay, led to the isolation of meliartenin, a limonoid antifeedant, which existed as a mixture of two interchangeable isomers. At 4 microg/cm2 and 1 microg/cm2, the isomeric mixture was as active as azadirachtin in strongly inhibiting the larval feeding of Epilachna paenulata Germ. (Coleoptera: Coccinellidae) and the polyphagous pest, Spodoptera eridania (Lepidoptera: Noctuidae), respectively.

  3. Solid Oxide Fuel Cell Development at Topsoe Fuel Cell A/S and Risø National Laboratory

    DEFF Research Database (Denmark)

    Christiansen, Niels; Hansen, J B.; Larsen, H H.

    2007-01-01

    The consortium of Topsoe Fuel Cell A/S and Riso National Laboratory has up-scaled its production capacity of anode-supported cells to about 1100 per week. Stacks are based on a compact thin plate multilayer design with metallic interconnects and 12x12 cm(2) or 18x18 cm(2) foot print. Larger (500 ...... to include ethanol and coal syngas by development of a new coke resistant catalyst suitable for future SOFC technology....

  4. Superintensive pulse slow neutron source SIN based on kaon factory

    International Nuclear Information System (INIS)

    Kolmichkov, N.V.; Laptev, V.D.; Matveev, V.A.

    1991-01-01

    Possibility of intensive pulse slow neutron source creation based on 45-GeV proton synchrotron of K-meson factory, planned to construction in INR AS USSR is considered. Calculated peak thermal neutrons flux density value, averaged on 'radiating' light-water moderator surface of 100 cm 2 is 6.6 x 10 17 neutrons/(cm 2 sec) for pulse duration of 35 microseconds. (author)

  5. SPECIFIC RESISTANCE AND SPECIFIC INTENSITY OF BELT SANDING OF WOOD

    Directory of Open Access Journals (Sweden)

    Boleslaw Porankiewicz

    2010-06-01

    Full Text Available This paper examines and discusses the specific belt sanding resistance K (N·cm-2 and specific belt sanding intensity SI (g·cm-2·min-1, for wood of Pinus sylvestris L., Picea abies L., Quercus robra L., Acer pseudoplatanus L., Alnus glutinosa Gaertn., and Populus Nigra L., by different sanding pressure pS, different sanding grit NG number, and different wood grain angles Phi(v.

  6. Evidence of two-stage melting of Wigner solids

    Science.gov (United States)

    Knighton, Talbot; Wu, Zhe; Huang, Jian; Serafin, Alessandro; Xia, J. S.; Pfeiffer, L. N.; West, K. W.

    2018-02-01

    Ultralow carrier concentrations of two-dimensional holes down to p =1 ×109cm-2 are realized. Remarkable insulating states are found below a critical density of pc=4 ×109cm-2 or rs≈40 . Sensitive dc V-I measurement as a function of temperature and electric field reveals a two-stage phase transition supporting the melting of a Wigner solid as a two-stage first-order transition.

  7. Surface modification of RuO2 electrodes by laser irradiation and ion ...

    Indian Academy of Sciences (India)

    RuO2 thin layers were deposited on Ti supports by thermal decomposition of RuCl3 at 400°C. Some of the samples were subjected to laser irradiation between 0.5 and 1.5 J cm-2. Some others to Kr bombardment with doses between 1015 and 1016 cm-2. Modifications introduced by the surface treatments were monitored ...

  8. Near-surface circulation and kinetic energy in the tropical Indian Ocean derived from lagrangian drifters

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Saji, P.K.; Almeida, A.M.

    .However,sincethepresentdatasetisthe mostextensiveofthistypeeverassembled,itprovidesoneofthebestestimatesofthesebullet5eldscurrentlyavailable.Ingeneral,thehighestvaluesof EMareassociatedwithstrongpersistentbullet6ows,themeridionalbullet6owsinthewesternbasin,andthezonalSEC.Aridgeof EM(. 20cm2s2 2...Shenoietal.:IndianOceancirculation ridge,abulgeofhigh EM(400cm2s2 2)extendseastward(offEastAfrica)along10°S;associatedwiththestrengtheningoftheSECwhenitbullet6owspastthenortherntipofMadagascar,wherethebuoysmovedwithspeeds . 50cms2 1.Southof20°S,the E...

  9. Low Level Laser Therapy for Traumatic Brain Injury

    Science.gov (United States)

    2015-10-01

    Department of Surgery). A project manager was also hired through a joint search between our team and the MGH ED and will replace the role previously... neuromuscular coordination), and Morris water maze (spatial learning and memory). A single exposure of 810 nm laser (18 J/cm2 delivered at 25 mW/cm2...treatments, is not due to Figure 3. Mean NSS ( neuromuscular coordination) scores of mice with moderate TBI receiving different numbers of daily tLLLT

  10. Short-pulse neodymium:yttrium-aluminium garnet (Nd:YAG 1064nm) laser irradiation photobiomodulates mitochondria activity and cellular multiplication of Paramecium primaurelia (Protozoa).

    Science.gov (United States)

    Amaroli, Andrea; Benedicenti, Alberico; Ravera, Silvia; Parker, Steven; Selting, Wayne; Panfoli, Isabella; Benedicenti, Stefano

    2017-10-01

    Few studies exist to explore the potential photobiomodulation (PBM) effect of neodymium:yttrium-aluminium garnet (Nd:YAG) laser irradiation using a flat-top handpiece delivery system. In this study, we explored the photobiomodulation effect of that laser, on Paramecium primaurelia. The parameters for the different study groups were: 0.50W, 10Hz, 100msp, 30J/cm 2 ; 0.75W, 10Hz, 100msp, 45J/cm 2 ; 1.00W, 10Hz, 100msp, 60J/cm 2 ; 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 . Our results suggest that only the parameter 0.5W, 10Hz, 100msp, 30J/cm 2 positively photobiomodulates the Paramecium cells inducing an increment in oxygen consumption, endogenous ATP synthesis and fission rate rhythm. Applying the laser energy with parameters of 1.25W, 10Hz, 100msp, 75J/cm 2 and 1.50W, 10Hz, 100msp, 90J/cm 2 , induce adverse effect on the Paramecium cells, which protect themselves through the increase in Heat Shock Protein-70 (HSP70). The data presented in our work support our assumption that, when using appropriate parameters of irradiation, the 1064nm Nd:YAG laser with flat-top handpiece could be a valuable aid for effective clinical application of PBM. Copyright © 2017 Elsevier GmbH. All rights reserved.

  11. Physical and mechanical properties of parallel strand lumber made from hot pre-pressed long strand oil palm trunk waste

    Science.gov (United States)

    Fridiyanti, Inayah; Massijaya, M. Y.

    2018-03-01

    This research was focused on the utilization of oil palm trunk waste as a Parallel Strand Lumber (PSL) raw material. This research aimed to analyze the effect of adhesive types and glue spreads to the physical and mechanical properties of PSL. The adhesive types used were isocyanate and urea formaldehyde adhesives. The glue spreads used were 150 g/m2 and 300 g/m2. The research results showed that the moisture content of PSL ranged from 9.30% to 11.80%. The PSL density ranged from 0.64 to 0.78 g/cm3. The volume shrinkage ranged from 5.69 to 7.17%. Modulus of Elasticity (MOE) parallel to the grain and edge side ranged from 51.6 × 103 to 98.3 × 103 kg/cm2, and 62.1 × 103 to 99.9 × 103 kg/cm2, respectively. The Modulus of Rupture (MOR) parallel to the grain and edge side ranged from 269 to 724 kg/cm2 and 342 to 728 kg/cm2, respectively. The PSL hardness perpendicular to the grain, parallel to the grain and the edge side ranged from 135 to 300 kg/cm2, 87 to 321 kg/cm2, and 128 to 251 kg/cm2, respectively. The compressive strength ranged from 181 to 231 kg/cm2. The best adhesive and glue spreads of PSL was isocyanate with glue spread 300 g/m2. PSL made from hot pre-pressed long strand of oil palm trunk waste bonded by isocyanate fulfill JAS 1152: 2007. However, those of bonded by urea formaldehyde failed to fulfill the standard. The physical and mechanical properties of PSL made from oil palm trunk were better compared to those of solid oil palm trunk.

  12. Ion yields of laser aligned CH3I and CH3Br from multiple orbitals

    NARCIS (Netherlands)

    He, Lanhai; Pan, Yun; Yang, Yujun; Luo, Sizuo; Lu, Chunjing; Zhao, Huifang; Li, Dongxu; Song, Lele; Stolte, Steven; Ding, Dajun; Roeterdink, Wim G.

    2016-01-01

    We have measured the alignment influence on ion yields of CH3I and CH3Br molecules in the laser intensity regime from 1013 W/cm2 to 1015 W/cm2. The hexapole state-selection technique combined with laser induced alignment has been employed to obtain aligned (〈P2(cosθ)〉=0.7) and anti-aligned

  13. Dynamic Regime of Ignition of Solid Propellant

    Directory of Open Access Journals (Sweden)

    Zolotorev Nikolay

    2016-01-01

    Full Text Available This article presents a dynamic regime of exposure of the radiant flux on the sample of gun-cotton. Obtained time the ignition of gun-cotton in the heating conditions of increasing heat flux in the range from 0.2 W/cm2 to 22 W/cm2. A comparison of the delay times of the ignition when heated variable and constant heat flux.

  14. Bio-Conjugated Polycaprolactone Membranes: A Novel Wound Dressing

    Directory of Open Access Journals (Sweden)

    Elijah Zhengyang Cai

    2014-11-01

    Full Text Available BackgroundThe combination of polycaprolactone and hyaluronic acid creates an ideal environment for wound healing. Hyaluronic acid maintains a moist wound environment and accelerates the in-growth of granulation tissue. Polycaprolactone has excellent mechanical strength, limits inflammation and is biocompatible. This study evaluates the safety and efficacy of bio-conjugated polycaprolactone membranes (BPM as a wound dressing.Methods16 New Zealand white rabbits were sedated and local anaesthesia was administered. Two 3.0×3.0 cm full-thickness wounds were created on the dorsum of each rabbit, between the lowest rib and the pelvic bone. The wounds were dressed with either BPM (n=12 or Mepitel (n=12 (control, a polyamide-silicon wound dressing. These were evaluated macroscopically on the 7th, 14th, 21st, and 28th postoperative days for granulation, re-epithelialization, infection, and wound size, and histologically for epidermal and dermal regeneration.ResultsBoth groups showed a comparable extent of granulation and re-epithelialization. No signs of infection were observed. There was no significant difference (P>0.05 in wound size between the two groups. BPM (n=6: 8.33 cm2, 4.90 cm2, 3.12 cm2, 1.84 cm2; Mepitel (n=6: 10.29 cm2, 5.53 cm2, 3.63 cm2, 2.02 cm2; at the 7th, 14th, 21st, and 28th postoperative days. The extents of epidermal and dermal regeneration were comparable between the two groups.ConclusionsBPM is comparable to Mepitel as a safe and efficacious wound dressing.

  15. High bone turnover is associated with low bone mass and spinal fracture in postmenopausal women

    DEFF Research Database (Denmark)

    Ravn, Pernille; Rix, M; Andreassen, H

    1997-01-01

    -eight women had a lumbar spine bone mineral density (BMD) above 0.860 g/cm2, and 278 women had a BMD below 0.860 g/cm2. Spinal fracture was diagnosed from lateral spine X-ray studies and defined as at least 20% height reduction (wedge, compression, or endplate fracture) in at least one vertebra (T4-L4). Bone...

  16. Diffusion of iodine and Technetium-99 through waste encasement concrete and unsaturated soil fill material

    International Nuclear Information System (INIS)

    Mattigod, Shas V.; Whyatt, Greg A.; Serne, R. JEFFREY; Wood, Marcus I.; Hanchar, John M.; Stores-Gascoyne, Simcha; Lauren Browning

    2004-01-01

    An assessment of long-term performance of low level waste-enclosing cement grouts requires diffusivity data for radionuclide species such as, 129I and 99Tc. The diffusivity of radionuclides in soil and concrete media was collected by conducting soil-soil and concrete-soil half-cell experiments. The soil diffusivity coefficients for iodide were 7.03 x 10-8 cm2/s and 2.42 x 10-7 cm2/s for soils at 4% and 7% moisture contents, respectively. Iodide diffusivity in soil is a function of moisture content and is about an order of magnitude slower at lower moisture content. The soil diffusivity coefficients for 99Tc were 5.89 ± 0.80 x 10-8 cm2/s (4% moisture content) and 2.04 ± 0.57 x 10-7 cm2/s (7% moisture content), respectively. The soil diffusivity of iodide and 99Tc were similar in magnitude at both water contents, indicating that these ions have similar diffusion mechanisms in unsaturated coarse-textured Hanford soil. The diffusivity of iodide in concrete ranged from 2.07 x 10-14 cm2/s (4% soil moisture content) to 1.31 x 10-12 cm2/s (7% soil moisture content), indicating that under unsaturated soil moisture conditions, iodide diffusivity is highly sensitive to changing soil moisture conditions. Depending on the soil moisture content, the diffusivity of 99Tc in concrete ranged from 4.54 x 10-13 cm2/s to 8.02 x 10-12 cm2/s. At 4% soil moisture content, iodide diffused about 20 times more slowly than 99Tc, and at 7% soil moisture content, iodide in concrete diffused about 6 times slower than 99Tc

  17. Positron annihilation and perturbed angular correlation studies of defects in neutron and heavy ion irradiated Si

    International Nuclear Information System (INIS)

    Zhu Shenyun; Li Anli; Li Donghong; Huang Hanchen; Zheng Shengnan; Du Hongshan; Ding Honglin; Gou Zhenhui; Iwata, T.

    1995-01-01

    The positron annihilation and perturbed angular correlation methods have been used to study the radiation damage induced defects in Si irradiated by the fast neutrons of 1.45x10 20 /cm 2 and the 178 W heavy ions of 5x10 11 /cm 2 . The divacancies, quadrivacancies and different types of monovacancy-, divacancy- and quadrivacancy-oxygen complexes were observed. The results obtained by both methods are consistent. (orig.)

  18. Preparation of tantalum targets of known thicknesses

    International Nuclear Information System (INIS)

    Alexander, J.R.; Wirth, H.L.

    1985-01-01

    A series of carbon-backed tantalum targets were produced in a heavy ion sputtering system with a Penning ion source. The target thicknesses were then measured using the alpha-ray energy loss method. The resulting tabulated measurements were reproducible and make possible the production of carbon-backed tantalum targets with pre-determined thicknesses ranging from 20 μg/cm 2 to 1 mg/cm 2 . (orig.)

  19. Association between abdominal fat distribution and atherosclerotic changes in the carotid artery.

    Science.gov (United States)

    Oike, Miki; Yokokawa, Hirohide; Fukuda, Hiroshi; Haniu, Tomomi; Oka, Fukuko; Hisaoka, Teruhiko; Isonuma, Hiroshi

    2014-01-01

    We aimed to evaluate the association between abdominal fat distribution (e.g., abdominal visceral fat area [VFA], subcutaneous fat area [SFA], and total fat area [TFA]), waist circumference (WC), or body mass index (BMI) and atherosclerotic changes in the carotid artery after adjusting for common risk factors. The present study is a hospital-based, cross-sectional study. Study participants included 223 Japanese individuals who underwent a medical health checkup at Juntendo University Hospital, Tokyo, between December 2005 and August 2011. Multivariate logistic regression analysis was used to examine the association between abdominal VFA, SFA, TFA, the VFA/SFA ratio, WC, or BMI and intima-media thickness [IMT] (mean IMT≥1.1mm or maximum IMT≥1.2mm) as atherosclerotic changes in the carotid artery. Multivariate logistic regression analysis showed that VFA (OR for ≥150cm(2) versus <100cm(2), 3.88; 95% CI, 1.39-10.85), BMI (OR for ≥27.6kg/m(2) versus <25kg/m(2), 5.22; 95% CI, 1.69-16.16), and TFA (OR for 200-285cm(2) versus <200cm(2), 4.15; 95% CI, 1.34-12.86: OR for ≥285cm(2) versus <200cm(2), 5.53; 95% CI, 1.76-17.35) were significantly associated with atherosclerotic changes in men. After adjustment for BMI, only TFA (OR for ≥285cm(2) versus <200cm(2), 3.76; 95%CI, 1.03-13.79) in men was significantly associated with atherosclerotic changes in the carotid artery. Our results indicate that VFA, TFA, and BMI are independently associated with atherosclerotic changes in Japanese men. TFA may be considered as a valuable measure of atherosclerotic changes. Copyright © 2013 Asian Oceanian Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

  20. Magnetic study of superconductivity in YBa2Cu3O7-x thin films

    International Nuclear Information System (INIS)

    McGuire, T.R.; Gupta, A.; Koren, G.; Laibowitz, R.B.; Dimos, D.

    1989-01-01

    Magnetic and transport measurements on 0.3 micron thick films of YBa 2 Cu 3 O 7 - x made by a laser ablation technique show critical current densities of up to 40X10 6 amps/cm 2 . At 77K the transport data gives J c ∼5x10 6 amps/cm 2 while magnetic data is 40 % lower. Comparison is made with evaporated films