WorldWideScience

Sample records for device quality nanocrystalline

  1. Mesoporous nanocrystalline film architecture for capacitive storage devices

    Science.gov (United States)

    Dunn, Bruce S.; Tolbert, Sarah H.; Wang, John; Brezesinski, Torsten; Gruner, George

    2017-05-16

    A mesoporous, nanocrystalline, metal oxide construct particularly suited for capacitive energy storage that has an architecture with short diffusion path lengths and large surface areas and a method for production are provided. Energy density is substantially increased without compromising the capacitive charge storage kinetics and electrode demonstrates long term cycling stability. Charge storage devices with electrodes using the construct can use three different charge storage mechanisms immersed in an electrolyte: (1) cations can be stored in a thin double layer at the electrode/electrolyte interface (non-faradaic mechanism); (2) cations can interact with the bulk of an electroactive material which then undergoes a redox reaction or phase change, as in conventional batteries (faradaic mechanism); or (3) cations can electrochemically adsorb onto the surface of a material through charge transfer processes (faradaic mechanism).

  2. Improved luminescence properties of nanocrystalline silicon based electroluminescent device by annealing

    International Nuclear Information System (INIS)

    Sato, Keisuke; Hirakuri, Kenji

    2006-01-01

    We report an annealing effect on electrical and luminescence properties of a red electroluminescent device consisting of nanocrystalline silicon (nc-Si). The red luminescence was generated by flowing the forward current into the device at a low threshold direct current (DC) forward voltage with a rise of annealing temperature up to 500 deg. C. Moreover, the luminescence of the device annealed at 500 deg. C was more intense than that of the device annealed at 200 deg. C or less under the same forward current density, because of the injection of a large quantity of carriers to the radiative recombination centers at the nc-Si surface vicinity. These were attained by a low resistivity of indium tin oxide (ITO) electrode and good contact at the ITO electrode/luminous layer interface region by the annealing treatment. The above results indicated that the annealing treatment of the device is effective for the realization of high luminance due to the improvement in the injection efficiency of carriers to the radiative recombination centers

  3. Nanocrystalline Silicon Carrier Collectors for Silicon Heterojunction Solar Cells and Impact on Low-Temperature Device Characteristics

    KAUST Repository

    Nogay, Gizem

    2016-09-26

    Silicon heterojunction solar cells typically use stacks of hydrogenated intrinsic/doped amorphous silicon layers as carrier selective contacts. However, the use of these layers may cause parasitic optical absorption losses and moderate fill factor (FF) values due to a high contact resistivity. In this study, we show that the replacement of doped amorphous silicon with nanocrystalline silicon is beneficial for device performance. Optically, we observe an improved short-circuit current density when these layers are applied to the front side of the device. Electrically, we observe a lower contact resistivity, as well as higher FF. Importantly, our cell parameter analysis, performed in a temperature range from -100 to +80 °C, reveals that the use of hole-collecting p-type nanocrystalline layer suppresses the carrier transport barrier, maintaining FF s in the range of 70% at -100 °C, whereas it drops to 40% for standard amorphous doped layers. The same analysis also reveals a saturation onset of the open-circuit voltage at -100 °C using doped nanocrystalline layers, compared with saturation onset at -60 °C for doped amorphous layers. These findings hint at a reduced importance of the parasitic Schottky barrier at the interface between the transparent electrodes and the selective contact in the case of nanocrystalline layer implementation. © 2011-2012 IEEE.

  4. Large area plasma-enhanced chemical vapor deposition of nanocrystalline graphite on insulator for electronic device application

    OpenAIRE

    Schmidt, Marek E.; Xu, Cigang; Cooke, Mike; Mizuta, Hiroshi; Chong, H.M.H.

    2012-01-01

    This paper reports on large area plasma-enhanced chemical vapor deposition (PECVD) of nanocrystalline graphite (NCG) on thermally grown SiO2 wafer, quartz and sapphire substrates. Grown films are evaluated using Raman spectroscopy, ellipsometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrical characterization and optical transmission measurementsindicate promising properties of this material for use as transparent electrodes and for electronic device applicati...

  5. Electrochromic devices based on wide band-gap nanocrystalline semiconductors functionalized with mononuclear charge transfer compounds

    DEFF Research Database (Denmark)

    Biancardo, M.; Argazzi, R.; Bignozzi, C.A.

    2006-01-01

    A series of ruthenium and iron mononuclear complexes were prepared and their spectroeletrochemical behavior characterized oil Optically Transparent Thin Layer Electrodes (OTTLE) and on Fluorine Doped SnO2 (FTO) conductive glasses coated with Sb-doped nanocrystalline SnO2. These systems display a ...

  6. Electrochromic devices based on binuclear mixed valence compounds adsorbed on nanocrystalline semiconductors.

    Science.gov (United States)

    Biancardo, Matteo; Schwab, Peter F H; Argazzi, Roberto; Bignozzi, Carlo Alberto

    2003-06-30

    A series of cyano-bridged binuclear mixed valence complexes of the general formula M-Ru(III)(NH(3))(4)pyCOOH [pyCOOH = isonicotinic acid; M = cis-Ru(bpy)(2)(CN)(2), 1 (bpy = 2,2' bipyridine); trans-Ru(py)(4)(CN)(2), 2 (py = pyridine); [Ru(CN)(6)](4)(-), 3; [Fe(CN)(6)](4)(-), 4] have been prepared and anchored through the carboxylic function to nanocrystalline TiO(2) or SnO(2) electrodes. The complexes display a reversible electrochromic behavior in the range of applied potential from -0.5 to +0.5 V, versus SCE. Tuning of the electronic transitions in the visible and near-infrared spectral regions is achieved through changes of the solvent and of the cyano-bridged metal moiety M.

  7. Infrared absorption study of hydrogen incorporation in thick nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Tang, C.J.; Neves, A.J.; Carmo, M.C.

    2005-01-01

    We present an infrared (IR) optical absorbance study of hydrogen incorporation in nanocrystalline diamond films. The thick nanocrystalline diamond films were synthesized by microwave plasma-assisted chemical vapor deposition and a high growth rate about 3.0 μm/h was achieved. The morphology, phase quality, and hydrogen incorporation were assessed by means of scanning electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Large amount of hydrogen bonded to nanocrystalline diamond is clearly evidenced by the huge CH stretching band in the FTIR spectrum. The mechanism of hydrogen incorporation is discussed in light of the growth mechanism of nanocrystalline diamond. This suggests the potential of nanocrystalline diamond for IR electro-optical device applications

  8. High optical quality nanocrystalline diamond with reduced non-diamond contamination

    Czech Academy of Sciences Publication Activity Database

    Remeš, Zdeněk; Ižák, Tibor; Kromka, Alexander; Vaněček, Milan

    2010-01-01

    Roč. 19, 5-6 (2010), s. 453-456 ISSN 0925-9635 R&D Projects: GA MŠk LC510; GA AV ČR(CZ) IAAX00100902 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond * photocurrent spectra * optical absorption * laser calorimetry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.825, year: 2010

  9. Quality control of imaging devices

    International Nuclear Information System (INIS)

    Soni, P.S.

    1992-01-01

    Quality assurance in nuclear medicine refers collectively to all aspects of a nuclear medicine service. It would include patient scheduling, radiopharmaceutical preparation and dispensing, radiation protection of patients, staff and general public, preventive maintenance and the care of instruments, methodology, data interpretation and records keeping, and many other small things which contribute directly or indirectly to the overall quality of a nuclear medicine service in a hospital. Quality Control, on the other hand, refers to a signal component of the system and is usually applied in relation to a specific instrument and its performance

  10. Nanocrystalline solids

    International Nuclear Information System (INIS)

    Gleiter, H.

    1991-01-01

    Nanocrystalline solids are polycrystals, the crystal size of which is a few (typically 1 to 10) nanometres so that 50% or more of the solid consists of incoherent interfaces between crystals of different orientations. Solids consisting primarily of internal interfaces represent a separate class of atomic structures because the atomic arrangement formed in the core of an interface is known to be an arrangement of minimum energy in the potential field of the two adjacent crystal lattices with different crystallographic orientations on either side of the boundary core. These boundary conditions result in atomic structures in the interfacial cores which cannot be formed elsewhere (e.g. in glasses or perfect crystals). Nanocrystalline solids are of interest for the following four reasons: (1) Nanocrystalline solids exhibit an atomic structure which differs from that of the two known solid states: the crystalline (with long-range order) and the glassy (with short-range order). (2) The properties of nanocrystalline solids differ (in some cases by several orders of magnitude) from those of glasses and/or crystals with the same chemical composition, which suggests that they may be utilized technologically in the future. (3) Nanocrystalline solids seem to permit the alloying of conventionally immiscible components. (4) If small (1 to 10 nm diameter) solid droplets with a glassy structure are consolidated (instead of small crystals), a new type of glass, called nanoglass, is obtained. Such glasses seem to differ structurally from conventional glasses. (orig.)

  11. Signal Quality Evaluation of Emerging EEG Devices

    Directory of Open Access Journals (Sweden)

    Thea Radüntz

    2018-02-01

    Full Text Available Electroencephalogram (EEG registration as a direct measure of brain activity has unique potentials. It is one of the most reliable and predicative indicators when studying human cognition, evaluating a subject's health condition, or monitoring their mental state. Unfortunately, standard signal acquisition procedures limit the usability of EEG devices and narrow their application outside the lab. Emerging sensor technology allows gel-free EEG registration and wireless signal transmission. Thus, it enables quick and easy application of EEG devices by users themselves. Although a main requirement for the interpretation of an EEG is good signal quality, there is a lack of research on this topic in relation to new devices. In our work, we compared the signal quality of six very different EEG devices. On six consecutive days, 24 subjects wore each device for 60 min and completed tasks and games on the computer. The registered signals were evaluated in the time and frequency domains. In the time domain, we examined the percentage of artifact-contaminated EEG segments and the signal-to-noise ratios. In the frequency domain, we focused on the band power variation in relation to task demands. The results indicated that the signal quality of a mobile, gel-based EEG system could not be surpassed by that of a gel-free system. However, some of the mobile dry-electrode devices offered signals that were almost comparable and were very promising. This study provided a differentiated view of the signal quality of emerging mobile and gel-free EEG recording technology and allowed an assessment of the functionality of the new devices. Hence, it provided a crucial prerequisite for their general application, while simultaneously supporting their further development.

  12. Nanocrystalline sol-gel Nb{sub 2}O{sub 5} coatings. Preparation, characterisation and application to photovoltaic cell, lithium battery and eletrochromic device

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yeping

    2002-07-01

    Thick and thin films of Nb{sub 2}O{sub 5} have been prepared by the sol-gel process using cheap niobium pentachloride as precursor and a new synthesis route. The microstructure of the films was tailored by adding poly(ethylene glycol) (PEG) and carbon soot into the sol and varying the sintering temperature. The thesis describes the properties of the sols and their influence on the properties of the resulting nanocrystalline Nb{sub 2}O{sub 5} films as electrodes in dye sensitised solar cells, electrochromic devices and rechargeable lithium batteries. A solar light-to-electric conversion efficiency of Ru(II) sensitised Nb{sub 2}O{sub 5} solar cell as high as 7% under 120 W/m{sup 2} illumination was obtained. An equivalent electric circuit of the dye sensitised electrode/electrolyte interface based on the electrochemical impedance spectroscopy was modelled and found to fit all the results. The values obtained for the electric elements from the simulation of the results were found to relate material parameters to the cell performance and their influence on the cell performance are illustrated. The electrochromism and Li{sup +}-charge and discharge of the Nb{sub 2}O{sub 5} films exhibited also good performance. (orig.)

  13. Nanocrystalline ceramic materials

    Science.gov (United States)

    Siegel, Richard W.; Nieman, G. William; Weertman, Julia R.

    1994-01-01

    A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

  14. Nanocrystalline diamond coatings for mechanical seals applications.

    Science.gov (United States)

    Santos, J A; Neto, V F; Ruch, D; Grácio, J

    2012-08-01

    A mechanical seal is a type of seal used in rotating equipment, such as pumps and compressors. It consists of a mechanism that assists the connection of the rotating shaft to the housings of the equipments, preventing leakage or avoiding contamination. A common cause of failure of these devices is end face wear out, thus the use of a hard, smooth and wear resistant coating such as nanocrystalline diamond would be of great importance to improve their working performance and increase their lifetime. In this paper, different diamond coatings were deposited by the HFCVD process, using different deposition conditions. Additionally, the as-grown films were characterized for, quality, morphology and microstructure using scanning electron microscopy (SEM) and Raman spectroscopy. The topography and the roughness of the films were characterized by atomic force microscopy (AFM).

  15. Security Issues for Information Quality on Mobile Devices

    Directory of Open Access Journals (Sweden)

    Dana Ramona ANDRISESCU

    2010-01-01

    Full Text Available Mobile devices are used everywhere, from making acall to store huge volume of information. But together withdevices shrinking and rise of storage space on a single device webring to mind the problem of trusting the stored information.Trusting the information and assuring its quality meansknowing the security threats these devices face and measuresthat should be taken. Many questions rise from here like “Whathappens when a mobile device is used by several persons andespecially employees?”, “Is that information reliable andoriginal?”, “Who is responsible for a device and its security?”.We are going to see in this paper that information quality can beassured even on portable devices by using the adequate securitymeasures.

  16. Quality Assurance in Custom Dental Devices: A Technologist's Perspective.

    Science.gov (United States)

    Griffin, Anthony

    2017-12-01

    Manufacturing of custom-made dental devices such as removable dentures, fixed prosthodontics and orthodontics are subject to the requirements of the Medical Devices Directive (MDD). Many dental laboratories often enhance these requirements by implementing quality assurance procedures that then provide enhanced consistency. this paper provides a dental technologist's view of some of the systems currently being used in dental laboratories to provide a quality assured product and associated issues.

  17. Nanocrystalline La1-xSrxCo1-yFe yO3 perovskites fabricated by the micro-emulsion route for high frequency response devices fabrications

    KAUST Repository

    Azhar Khan, Muhammad

    2014-09-01

    Nanocrystalline La1-xSrxCo1-yFe yO3 (x=0.00-0.60) perovskites were fabricated by a cheap economic route (i.e. micro-emulsion method) and characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). TGA analysis showed ~35% weight loss. The crystallite size determined by XRD and SEM ranged from 30 to 80 nm and ~30 to 50 nm, respectively. The dielectric behavior was evaluated in the range of 1.0×106 Hz to 3.0×10 9 Hz at 298 K, the dielectric parameters resulting appreciably enhanced by co-doping with Sr and Fe. The maximum dielectric parameters (ε′=103.35, ε″=58.92 and tan δ=0.57) were observed for La0.4Sr0.6Co0.4Fe0.6O 3 at 15×106 Hz. Results suggest the potential use of these nanocrystalline perovskites in GHz-operated microwave devices. © 2014 Elsevier Ltd and Techna Group S.r.l.

  18. Display device-adapted video quality-of-experience assessment

    Science.gov (United States)

    Rehman, Abdul; Zeng, Kai; Wang, Zhou

    2015-03-01

    Today's viewers consume video content from a variety of connected devices, including smart phones, tablets, notebooks, TVs, and PCs. This imposes significant challenges for managing video traffic efficiently to ensure an acceptable quality-of-experience (QoE) for the end users as the perceptual quality of video content strongly depends on the properties of the display device and the viewing conditions. State-of-the-art full-reference objective video quality assessment algorithms do not take into account the combined impact of display device properties, viewing conditions, and video resolution while performing video quality assessment. We performed a subjective study in order to understand the impact of aforementioned factors on perceptual video QoE. We also propose a full reference video QoE measure, named SSIMplus, that provides real-time prediction of the perceptual quality of a video based on human visual system behaviors, video content characteristics (such as spatial and temporal complexity, and video resolution), display device properties (such as screen size, resolution, and brightness), and viewing conditions (such as viewing distance and angle). Experimental results have shown that the proposed algorithm outperforms state-of-the-art video quality measures in terms of accuracy and speed.

  19. Ensuring a High Quality Digital Device through Design for Testability

    OpenAIRE

    Ngene, Christopher Umerah

    2012-01-01

    An electronic device is reliable if it is available for use most of the times throughout its life. The reliability can be affected by mishandling and use under abnormal operating conditions. High quality product cannot be achieved without proper verification and testing during the product development cycle. If the design is difficult to test, then it is very likely that most of the faults will not be detected before it is shipped to the customer. This paper describes how product quality can b...

  20. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  1. Effectiveness of the stormwater quality devices to improve water quality at Putrajaya

    International Nuclear Information System (INIS)

    Sidek, L M; Basri, H; Puad, A H Mohd; Noh, M N Md; Ainan, A

    2013-01-01

    Development of Putrajaya has changed the character of the natural landform by covering the land with impervious surfaces. Houses, office buildings, commercial place and shopping centres have provided places to live and work. The route between buildings is facilitated and encouraged by a complex network of roads and car parks. However, this change from natural landforms and vegetative cover to impervious surfaces has major effect on stormwater which are water quality (non-point source pollution). This paper describes the effectiveness of the stormwater quality devices to improve water quality at selected Putrajaya for demonstration in order to evaluate low cost storm inlet type devices in the Putrajaya Catchment. Five stormwater quality devices were installed and monitored during the study. The devices include Ultra Drain Guard Recycle model, Ultra Curb Guard Plus, Ultra Grate Guard, Absorbent Tarp and Ultra Passive Skimmer. This paper will provide information on the benefits and costs of these devices, including operations and maintenance requirements. Applicability of these devices in gas stations, small convenience stores, residential and small parking lots in the catchment are possible due to their low cost.

  2. 75 FR 391 - Medical Device Quality System Regulation Educational Forum on Risk Management Through the Product...

    Science.gov (United States)

    2010-01-05

    ... Cycle; Public Workshop AGENCY: Food and Drug Administration, HHS. ACTION: Notice of public workshop...), is announcing a public workshop entitled ``Medical Device Quality System Regulation Educational Forum... information about FDA's Medical Device Quality Systems Regulation (QSR) to the regulated industry...

  3. Low cost and efficient photovoltaic conversion by nanocrystalline solar cells

    International Nuclear Information System (INIS)

    Graetzel, Michael

    1995-01-01

    The quality of human life depends to a large degree on the availability of energy sources. The present worldwide energy consumption already exceeds the level of 6000 gigawatt and is expected to further increase sharply. This implies enhanced depletion of fossil fuel reserves, leading to further aggravation of the environmental pollution. Adding to this the dangers arising from the accumulation of plutonium fission products from nuclear reactors, the quality of life on earth is threatened unless renewable energy resources can be quickly developed. Photovoltaic solar energy converters are expected to make important contributions to the identification of environmentally friendly solutions to the energy problem. One attractive strategy discussed in this paper is the development of systems that mimic natural photosynthesis in the conversion of solar energy for the fixation of carbon dioxide. A molecular photovoltaic device has been developed whose overall efficiency for solar energy conversion to electricity has already attained 10%. The system is based on the sensitization of nanocrystalline films by transition metal charge transfer sensitizers. In analogy to photosynthesis, the new chemical solar cell achieves the separation of the light absorption and charge carrier transport processes. Extraordinary yields exceeding 90% for the conversion of incident photons into electric current are obtained, in contrast to conventional photovoltaic cells which are not economical for base load utility electricity production. The low cost and ease of production of the new cell should benefit large-scale applications, in particular in underdeveloped or developing countries, which benefit from generous sunshine. Aside from its intrinsic merits as a photovoltaic device, nanocrystalline film development opens up a large number of additional avenues for energy storage ranging from intercalation batteries to the formation of chemical fuels. These systems will undoubtedly promote the

  4. Nanofluidic device for continuous multiparameter quality assurance of biologics.

    Science.gov (United States)

    Ko, Sung Hee; Chandra, Divya; Ouyang, Wei; Kwon, Taehong; Karande, Pankaj; Han, Jongyoon

    2017-08-01

    Process analytical technology (PAT) is critical for the manufacture of high-quality biologics as it enables continuous, real-time and on-line/at-line monitoring during biomanufacturing processes. The conventional analytical tools currently used have many restrictions to realizing the PAT of current and future biomanufacturing. Here we describe a nanofluidic device for the continuous monitoring of biologics' purity and bioactivity with high sensitivity, resolution and speed. Periodic and angled nanofilter arrays served as the molecular sieve structures to conduct a continuous size-based analysis of biologics. A multiparameter quality monitoring of three separate commercial biologic samples within 50 minutes has been demonstrated, with 20 µl of sample consumption, inclusive of dead volume in the reservoirs. Additionally, a proof-of-concept prototype system, which integrates an on-line sample-preparation system and the nanofluidic device, was demonstrated for at-line monitoring. Thus, the system is ideal for on-site monitoring, and the real-time quality assurance of biologics throughout the biomanufacturing processes.

  5. Processing of nanocrystalline diamond thin films for thermal management of wide-bandgap semiconductor power electronics

    International Nuclear Information System (INIS)

    Govindaraju, N.; Singh, R.N.

    2011-01-01

    Highlights: → Studied effect of nanocrystalline diamond (NCD) deposition on device metallization. → Deposited NCD on to top of High Electron Mobility Transistors (HEMTs) and Si devices. → Temperatures below 290 deg. C for Si devices and 320 deg. C for HEMTs prevent metal damage. → Development of novel NCD-based thermal management for power electronics feasible. - Abstract: High current densities in wide-bandgap semiconductor electronics operating at high power levels results in significant self-heating of devices, which necessitates the development thermal management technologies to effectively dissipate the generated heat. This paper lays the foundation for the development of such technology by ascertaining process conditions for depositing nanocrystalline diamond (NCD) on AlGaN/GaN High Electron Mobility Transistors (HEMTs) with no visible damage to device metallization. NCD deposition is carried out on Si and GaN HEMTs with Au/Ni metallization. Raman spectroscopy, optical and scanning electron microscopy are used to evaluate the quality of the deposited NCD films. Si device metallization is used as a test bed for developing process conditions for NCD deposition on AlGaN/GaN HEMTs. Results indicate that no visible damage occurs to the device metallization for deposition conditions below 290 deg. C for Si devices and below 320 deg. C for the AlGaN/GaN HEMTs. Possible mechanisms for metallization damage above the deposition temperature are enumerated. Electrical testing of the AlGaN/GaN HEMTs indicates that it is indeed possible to deposit NCD on GaN-based devices with no significant degradation in device performance.

  6. Medical Devices; Immunology and Microbiology Devices; Classification of the Assayed Quality Control Material for Clinical Microbiology Assays. Final order.

    Science.gov (United States)

    2017-07-27

    The Food and Drug Administration (FDA, Agency, or we) is classifying the assayed quality control material for clinical microbiology assays into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the assayed quality control material for clinical microbiology assays' classification. The Agency is classifying the device into class II (special controls) to provide a reasonable assurance of safety and effectiveness of the device.

  7. A systematic quality assurance study in bone densitometry devices

    Science.gov (United States)

    Tuncman, Duygu; Kovan, Hatice; Kovan, Bilal; Demir, Bayram; Turkmen, Cuneyt

    2015-07-01

    Osteoporosis is the most common metabolic bone disease and can result in devastating physical, psychosocial, and economic consequences. It occurs in women after menopause and affects most elderly. Dual-energy x-ray absorptiometry (DXA) is currently the most widely used method for the measurement of areal Bone Mineral Density (BMD) (g/cm2) .DXA is based on the variable absorption of X-ray by the different body components and uses high and low energy X-ray photons. There are two important values in the assessment of the DXA. These values are T-score and Z-score. The T-score is calculated by taking the difference between a patient's measured BMD with the mean BMD of the young normal population, matched for gender and ethnicity, and then by dividing the difference with the standard deviation (SD) of the BMD of the young normal population. T-score and also Z-score are directly depends on the Bone Mineral Density (BMD). BMD measurements should be made periodically in a patient life. But mostly, it is not possible with the same device. Therefore, in this study, for the quality assurance of bone densitometry devices, we evaluated the BMD results measured in the different Bone Densitometry (DXA) devices using a spine phantom.

  8. Pilot for the Australian Breast Device Registry (ABDR): a national opt-out clinical quality registry for breast device surgery.

    Science.gov (United States)

    Hopper, Ingrid; Best, Renee L; McNeil, John J; Mulvany, Catherine M; Moore, Colin C M; Elder, Elisabeth; Pase, Marie; Cooter, Rodney D; Evans, Sue M

    2017-12-28

    To establish a pilot clinical quality registry (CQR) to monitor the quality of care and device performance for breast device surgery in Australia. All patients having breast device surgery from contributing hospitals in Australia. A literature review was performed which identified quality indicators for breast device surgery. A pilot CQR was established in 2011 to capture prospective data on breast device surgery. An interim Steering Committee and Management Committee were established to provide clinical governance, and guide quality indicator selection. The registry's minimum dataset was formulated in consultation with stakeholder groups; potential quality indicators were assessed in terms of (1) importance and relevance, (2) usability, (3) feasibility to collect and (4) scientific validity. Data collection was by a two-sided paper-based form with manual data entry. Seven sites were recruited, including one public hospital, four private hospitals and two day surgeries. Patients were recruited and opt-out consent used. The pilot breast device registry provides high-quality population-based data. It provides a model for developing a national CQR for breast devices; its minimum dataset and quality indicators reflect the opinions of the broad range of stakeholders. It is easily scalable, and has formed the basis for other international surgical groups establishing similar registries. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  9. Medical devices; immunology and microbiology devices; classification of quality control material for cystic fibrosis nucleic acid assays. Final rule.

    Science.gov (United States)

    2007-01-10

    The Food and Drug Administration (FDA) is classifying quality control material for cystic fibrosis nucleic acid assays into class II (special controls). The special control that will apply to the device is the guidance document entitled "Class II Special Controls Guidance Document: Quality Control Material for Cystic Fibrosis Nucleic Acid Assays." The agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for this device.

  10. Optimization of nanocrystalline γ-alumina coating for direct spray ...

    Indian Academy of Sciences (India)

    7, December 2014, pp. 1583–1588. c Indian Academy of Sciences. Optimization of nanocrystalline γ-alumina coating for direct spray water-cooling of optical devices. S N ALAM1,2,∗. , M ANARAKY3, Z SHAFEIZADEH3 and P J PARBROOK1. 1Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, ...

  11. ISO 13485: a complete guide to quality management in the medical device industry

    National Research Council Canada - National Science Library

    Abuhav, Itay

    2012-01-01

    .... Written by an experienced industry professional, this practical book provides a complete guide to the ISO 13485 standard certification for medical device manufacturing in terms of quality control...

  12. Magnetism in nanocrystalline gold.

    Science.gov (United States)

    Tuboltsev, Vladimir; Savin, Alexander; Pirojenko, Alexandre; Räisänen, Jyrki

    2013-08-27

    While bulk gold is well known to be diamagnetic, there is a growing body of convincing experimental and theoretical work indicating that nanostructured gold can be imparted with unconventional magnetic properties. Bridging the current gap in experimental study of magnetism in bare gold nanomaterials, we report here on magnetism in gold nanocrystalline films produced by cluster deposition in the aggregate form that can be considered as a crossover state between a nanocluster and a continuous film. We demonstrate ferromagnetic-like hysteretic magnetization with temperature dependence indicative of spin-glass-like behavior and find this to be consistent with theoretical predictions, available in the literature, based on first-principles calculations.

  13. Evaluation of working air quality by using semipermeable membrane devices

    International Nuclear Information System (INIS)

    Esteve-Turrillas, Francesc A.; Pastor, Agustin; Guardia, Miguel de la

    2008-01-01

    It has been evaluated the use of semipermeable membrane devices (SPMDs) as passive samplers of organophosphorus pesticides from air, in order to determine the contamination of working environments. Additionally, the use of SPMDs as portable samplers has been also considered. The analytical methodology for the determination of diazinon, chlorpyrifos-methyl, pirimiphos-methyl, chlorpyrifos and fenthion in SPMDs exposed to contaminated air was based on microwave-assisted extraction and gas chromatography with mass spectrometry determination. Limit of detection (LOD) values from 2 to 4 ng SPMD -1 and repeatability from 2 to 7% were obtained by using the aforementioned methodology. Theoretical calculated sampling rates were employed for the estimation of the pesticide concentration in air, by using the pesticide mass retained in the deployed SPMD. The obtained LOD values, for a sampling time of 7 days, were from 1 to 2 ng m -3 . The evaluation of the air quality of a pesticide laboratory with an intensive use of diazinon and chlorpyrifos has been made in order to check the operation safety conditions

  14. Evaluation of working air quality by using semipermeable membrane devices

    Energy Technology Data Exchange (ETDEWEB)

    Esteve-Turrillas, Francesc A. [Analytical Chemistry Department, University of Valencia, Edifici Jeroni Munoz, 50 Dr. Moliner, 46100 Burjassot, Valencia (Spain); Pastor, Agustin [Analytical Chemistry Department, University of Valencia, Edifici Jeroni Munoz, 50 Dr. Moliner, 46100 Burjassot, Valencia (Spain)], E-mail: agustin.pastor@uv.es; Guardia, Miguel de la [Analytical Chemistry Department, University of Valencia, Edifici Jeroni Munoz, 50 Dr. Moliner, 46100 Burjassot, Valencia (Spain)

    2008-09-19

    It has been evaluated the use of semipermeable membrane devices (SPMDs) as passive samplers of organophosphorus pesticides from air, in order to determine the contamination of working environments. Additionally, the use of SPMDs as portable samplers has been also considered. The analytical methodology for the determination of diazinon, chlorpyrifos-methyl, pirimiphos-methyl, chlorpyrifos and fenthion in SPMDs exposed to contaminated air was based on microwave-assisted extraction and gas chromatography with mass spectrometry determination. Limit of detection (LOD) values from 2 to 4 ng SPMD{sup -1} and repeatability from 2 to 7% were obtained by using the aforementioned methodology. Theoretical calculated sampling rates were employed for the estimation of the pesticide concentration in air, by using the pesticide mass retained in the deployed SPMD. The obtained LOD values, for a sampling time of 7 days, were from 1 to 2 ng m{sup -3}. The evaluation of the air quality of a pesticide laboratory with an intensive use of diazinon and chlorpyrifos has been made in order to check the operation safety conditions.

  15. Development of an electronic device quality aluminum antimonide (AlSb) semiconductor for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Sherohman, John W; Yee, Jick Hong; Combs, III, Arthur W

    2014-11-11

    Electronic device quality Aluminum Antimonide (AlSb)-based single crystals produced by controlled atmospheric annealing are utilized in various configurations for solar cell applications. Like that of a GaAs-based solar cell devices, the AlSb-based solar cell devices as disclosed herein provides direct conversion of solar energy to electrical power.

  16. 30 CFR 75.320 - Air quality detectors and measurement devices.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Air quality detectors and measurement devices. 75.320 Section 75.320 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.320 Air quality detectors and measurement devices. (a)...

  17. Simulation of devices mobility to estimate wireless channel quality metrics in 5G networks

    Science.gov (United States)

    Orlov, Yu.; Fedorov, S.; Samuylov, A.; Gaidamaka, Yu.; Molchanov, D.

    2017-07-01

    The problem of channel quality estimation for devices in a wireless 5G network is formulated. As a performance metrics of interest we choose the signal-to-interference-plus-noise ratio, which depends essentially on the distance between the communicating devices. A model with a plurality of moving devices in a bounded three-dimensional space and a simulation algorithm to determine the distances between the devices for a given motion model are devised.

  18. Light emission, light detection and strain sensing with nanocrystalline graphene

    International Nuclear Information System (INIS)

    Riaz, Adnan; Pyatkov, Feliks; Alam, Asiful; Dehm, Simone; Chakravadhanula, Venkata S K; Flavel, Benjamin S; Kübel, Christian; Krupke, Ralph; Felten, Alexandre; Lemmer, Uli

    2015-01-01

    Graphene is of increasing interest for optoelectronic applications exploiting light detection, light emission and light modulation. Intrinsically, the light–matter interaction in graphene is of a broadband type. However, by integrating graphene into optical micro-cavities narrow-band light emitters and detectors have also been demonstrated. These devices benefit from the transparency, conductivity and processability of the atomically thin material. To this end, we explore in this work the feasibility of replacing graphene with nanocrystalline graphene, a material which can be grown on dielectric surfaces without catalyst by graphitization of polymeric films. We have studied the formation of nanocrystalline graphene on various substrates and under different graphitization conditions. The samples were characterized by resistance, optical transmission, Raman and x-ray photoelectron spectroscopy, atomic force microscopy and electron microscopy measurements. The conducting and transparent wafer-scale material with nanometer grain size was also patterned and integrated into devices for studying light–matter interaction. The measurements show that nanocrystalline graphene can be exploited as an incandescent emitter and bolometric detector similar to crystalline graphene. Moreover the material exhibits piezoresistive behavior which makes nanocrystalline graphene interesting for transparent strain sensors. (paper)

  19. Mobility Device Quality Affects Participation Outcomes for People With Disabilities: A Structural Equation Modeling Analysis.

    Science.gov (United States)

    Magasi, Susan; Wong, Alex; Miskovic, Ana; Tulsky, David; Heinemann, Allen W

    2018-01-01

    To test the effect that indicators of mobility device quality have on participation outcomes in community-dwelling adults with spinal cord injury, traumatic brain injury, and stroke by using structural equation modeling. Survey, cross-sectional study, and model testing. Clinical research space at 2 academic medical centers and 1 free-standing rehabilitation hospital. Community-dwelling adults (N=250; mean age, 48±14.3y) with spinal cord injury, traumatic brain injury, and stroke. Not applicable. The Mobility Device Impact Scale, Patient-Reported Outcomes Measurement Information System Social Function (version 2.0) scale, including Ability to Participate in Social Roles and Activities and Satisfaction with Social Roles and Activities, and the 2 Community Participation Indicators' enfranchisement scales. Details about device quality (reparability, reliability, ease of maintenance) and device type were also collected. Respondents used ambulation aids (30%), manual (34%), and power wheelchairs (30%). Indicators of device quality had a moderating effect on participation outcomes, with 3 device quality variables (repairability, ease of maintenance, device reliability) accounting for 20% of the variance in participation. Wheelchair users reported lower participation enfranchisement than did ambulation aid users. Mobility device quality plays an important role in participation outcomes. It is critical that people have access to mobility devices and that these devices be reliable. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  20. Nanocrystalline silver dressings in wound management: a review

    Science.gov (United States)

    Fong, Joy; Wood, Fiona

    2006-01-01

    This paper describes the properties of nanocrystalline silver products (Acticoat™) and their applications and examines available evidence supporting their use in wound management. Acticoat utilizes nanotechnology to release nanocrystalline silver crystals. Acticoat releases 30 times less silver cations than silversulfadiazine cream or 0.5% silver nitrate solution but more of the silver released (by Acticoat). Silver-impregnated slow-release dressings release minute concentrations of silver which are quickly bound up by the chloride in the wound exudate. While extrapolations from in vitro and animal studies are cautious, evidence from these studies suggests Acticoat is: effective against most common strains of wound pathogens; can be used as a protective covering over skin grafts; has a broader antibiotic spectrum activity; and is toxic to keratinocytes and fibroblasts. Animal studies suggest a role for nanocrystalline silver in altering wound inflammatory events and facilitation of the early phase of wound healing. Quality human clinical trials into nanocrystalline silver are few. However, evidence suggests using Acticoat in wound management is cost effective, reduces wound infection, decreases the frequency of dressing changes and pain levels, decreases matrix metalloproteinase activity, wound exudate and bioburden levels, and promotes wound healing in chronic wounds. Although there is no in vivo evidence to suggest nanocrystalline silver is toxic to human keratinocytes and fibroblasts, there is in vitro evidence to suggest so; thus these dressings should be used cautiously over epithelializing and proliferating wounds. Future clinical research, preferably randomized controlled trials into nanocrystalline silver technology, may provide clinicians a better understanding of its applications in wound management. PMID:17722278

  1. Characterisation of interfaces in nanocrystalline palladium

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Characterisation of interfaces in nanocrystalline palladium. 49. Interface structures in nanocrystalline materials have been the subject of research from the very beginning. The first indication that the structure of grain boundaries in nanocrystalline materials was different was from the X-ray diffraction (XRD) studies of Zhu et al ...

  2. High-quality reduced graphene oxide-nanocrystalline platinum hybrid materials prepared by simultaneous co-reduction of graphene oxide and chloroplatinic acid

    Directory of Open Access Journals (Sweden)

    Wang Yinjie

    2011-01-01

    Full Text Available Abstract Reduced graphene oxide-nanocrystalline platinum (RGO-Pt hybrid materials were synthesized by simultaneous co-reduction of graphene oxide (GO and chloroplatinic acid with sodium citrate in water at 80°C, of pH 7 and 10. The resultant RGO-Pt hybrid materials were characterized using transmission electron microscopy (TEM, powder X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Platinum (Pt nanoparticles were anchored randomly onto the reduced GO (RGO sheets with average mean diameters of 1.76 (pH 7 and 1.93 nm (pH 10. The significant Pt diffraction peaks and the decreased intensity of (002 peak in the XRD patterns of RGO-Pt hybrid materials confirmed that the Pt nanoparticles were anchored onto the RGO sheets and intercalated into the stacked RGO layers at these two pH values. The Pt loadings for the hybrid materials were determined as 36.83 (pH 7 and 49.18% (pH 10 by mass using XPS analysis. With the assistance of oleylamine, the resultant RGO-Pt hybrid materials were soluble in the nonpolar organic solvents, and the dispersion could remain stable for several months.

  3. Assurance of Medical Device Quality with Quality Management System: An Analysis of Good Manufacturing Practice Implementation in Taiwan

    Directory of Open Access Journals (Sweden)

    Tzu-Wei Li

    2015-01-01

    Full Text Available The implementation of an effective quality management system has always been considered a principal method for a manufacturer to maintain and improve its product and service quality. Globally many regulatory authorities incorporate quality management system as one of the mandatory requirements for the regulatory control of high-risk medical devices. The present study aims to analyze the GMP enforcement experience in Taiwan between 1998 and 2013. It describes the regulatory implementation of medical device GMP requirement and initiatives taken to assist small and medium-sized enterprises in compliance with the regulatory requirement. Based on statistical data collected by the competent authority and industry research institutes, the present paper reports the growth of Taiwan local medical device industry after the enforcement of GMP regulation. Transition in the production, technologies, and number of employees of Taiwan medical device industry between 1998 and 2013 provides the competent authorities around the world with an empirical foundation for further policy development.

  4. Considerations of Poka-Yoke device in total quality management

    OpenAIRE

    Claudiu Isac; Alin Isac

    2002-01-01

    Poka-Yoke is the Japanese term for mistake-proofing. Developed by Dr. Shigeo Shingo, Poka-Yoke employs devices on the process operations to prevent the special causes that result in defects, or to inexpensively inspect each item that is produced to determine whether it is acceptable or defective

  5. Transtech PQI 301 pavement quality indicator device evaluation.

    Science.gov (United States)

    2010-10-01

    The PQI 301 Asphalt Density device, developed by Transtech Systems, Inc., was evaluated by MDOT to determine if it could be used in lieu of the currently required nuclear density gauge. Nuclear density gauges require MDOT personnel to have a license,...

  6. Impact of Mobility Device Use on Quality of Life in Children With Friedreich Ataxia.

    Science.gov (United States)

    Ejaz, Resham; Chen, Shiyi; Isaacs, Charles J; Carnevale, Amanda; Wilson, Judith; George, Kristen; Delatycki, Martin B; Perlman, Susan L; Mathews, Katherine D; Wilmot, George R; Hoyle, J Chad; Subramony, Sub H; Zesiewicz, Theresa; Farmer, Jennifer M; Lynch, David R; Yoon, Grace

    2018-01-01

    To determine how mobility device use impacts quality of life in children with Friedreich ataxia. Data from 111 pediatric patients with genetically confirmed Friedreich ataxia were collected from a prospective natural history study utilizing standardized clinical evaluations, including health-related quality of life using the Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Module. Mobility device use was associated with worse mean PedsQL total, physical, emotional, social, and academic subscores, after adjusting for gender, age of disease onset, and Friedreich Ataxia Rating Scale score. The magnitude of the difference was greatest for the physical subscore (-19.5 points, 95% CI = -30.00, -8.99, P mobility devices trended toward worse physical subscore (-16.20 points, 95% CI = -32.07, -0.33, P = .05). Mobility device use is associated with significant worsening of all domains of quality of life in children with Friedreich ataxia.

  7. 78 FR 12067 - Extreme Weather Effects on Medical Device Safety and Quality

    Science.gov (United States)

    2013-02-21

    ... safety and quality. DATES: Submit either electronic or written comments by May 10, 2013. ADDRESSES: Submit electronic comments to http://www.regulations.gov . Submit written comments to the Division of... situations in the future. Scenario A. Marketed Devices Already in Use for Patient Care Medical devices in use...

  8. Ultra-nanocrystalline diamond electrodes: optimization towards neural stimulation applications.

    Science.gov (United States)

    Garrett, David J; Ganesan, Kumaravelu; Stacey, Alastair; Fox, Kate; Meffin, Hamish; Prawer, Steven

    2012-02-01

    Diamond is well known to possess many favourable qualities for implantation into living tissue including biocompatibility, biostability, and for some applications hardness. However, conducting diamond has not, to date, been exploited in neural stimulation electrodes due to very low electrochemical double layer capacitance values that have been previously reported. Here we present electrochemical characterization of ultra-nanocrystalline diamond electrodes grown in the presence of nitrogen (N-UNCD) that exhibit charge injection capacity values as high as 163 µC cm(-2) indicating that N-UNCD is a viable material for microelectrode fabrication. Furthermore, we show that the maximum charge injection of N-UNCD can be increased by tailoring growth conditions and by subsequent electrochemical activation. For applications requiring yet higher charge injection, we show that N-UNCD electrodes can be readily metalized with platinum or iridium, further increasing charge injection capacity. Using such materials an implantable neural stimulation device fabricated from a single piece of bio-permanent material becomes feasible. This has significant advantages in terms of the physical stability and hermeticity of a long-term bionic implant.

  9. New lighting for the design of high quality biomedical devices

    Science.gov (United States)

    Jaffe, Claudia B.; Jaffe, Steven M.; Conner, Arlie R.

    2009-02-01

    Among the trends redefining 21st century biomedical diagnostics and therapeutics are the advent of low-cost portable analyzers. Because light is a powerful tool in many of today's most widely used life science instruments, high intensity, low cost light engines are essential to the design and proliferation of the newest bioanalytical instruments, medical devices and miniaturized analyzers. The development of new light technology represents a critical technical hurdle in the realization of point-of-care analysis. Lumencor has developed an inexpensive lighting solution, uniquely well suited to the production of safe, effective and commercially viable life science tools and biomedical devices. Lumencor's proprietary, solid-state light engine provides powerful, pure, stable, inexpensive light across the UV-Vis- NIR. Light engines are designed to directly replace the entire configuration of light management components with a single, simple unit. Power, spectral breadth and purity, stability and reliability data will demonstrate the advantages of these light engines for today's bioanalytical needs. Performance and cost analyses will be compared to traditional optical subsystems based on lamps, lasers and LEDs with respect to their suitability as sources for biomedical applications, implementation for development/evaluation of novel measurement tools and overall superior reliability. Next generation products based on such sources will be described to fulfill the demand for portable, hand-held analyzers and affordable devices with highly integrated light sources. A four color violet/cyan/green/red product will be demonstrated. A variety of multicolor prototypes, their spectral outputs and facile modulation will be discussed and their performance capabilities disclosed.

  10. Application of Devices and Systems Designed for Power Quality Monitoring and Assessment

    Directory of Open Access Journals (Sweden)

    Wiesław Gil

    2014-03-01

    Full Text Available The paper presents the problems associated with increasing demands on the equipment and systems for power quality assessment (PQ, installed at power substations. Difficulties are signaled due to current lack of standards defining the test methodology of measuring devices. The necessary device properties and the structure of a large system operated in real time and designed to assess the PQ are discussed. The usefulness of multi-channel analyzers featuring the identification and registration of transients is pointed out. The desirability of synchrophasor assessment implementation and device integration by standard PN-EN 61850 with other SAS devices is also justified.

  11. Toughness and strength of nanocrystalline graphene

    Science.gov (United States)

    Shekhawat, Ashivni; Ritchie, Robert O.

    2016-01-01

    Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects—grain boundaries and grain-boundary triple junctions—that lead to significant statistical fluctuations in toughness and strength. These fluctuations become particularly pronounced for nanocrystalline graphene where the density of defects is high. Here we use large-scale simulation and continuum modelling to show that the statistical variation in toughness and strength can be understood with ‘weakest-link' statistics. We develop the first statistical theory of toughness in polycrystalline graphene, and elucidate the nanoscale origins of the grain-size dependence of its strength and toughness. Our results should lead to more reliable graphene device design, and provide a framework to interpret experimental results in a broad class of two-dimensional materials. PMID:26817712

  12. Large-scale nanoelectromechanical switches based on directly deposited nanocrystalline graphene on insulating substrates

    Science.gov (United States)

    Sun, Jian; Schmidt, Marek E.; Muruganathan, Manoharan; Chong, Harold M. H.; Mizuta, Hiroshi

    2016-03-01

    The direct growth of graphene on insulating substrate is highly desirable for the commercial scale integration of graphene due to the potential lower cost and better process control. We report a simple, direct deposition of nanocrystalline graphene (NCG) on insulating substrates via catalyst-free plasma-enhanced chemical vapor deposition at relatively low temperature of ~800 °C. The parametric study of the process conditions that we conducted reveals the deposition mechanism and allows us to grow high quality films. Based on such film, we demonstrate the fabrication of a large-scale array of nanoelectromechanical (NEM) switches using regular thin film process techniques, with no transfer required. Thanks to ultra-low thickness, good uniformity, and high Young's modulus of ~0.86 TPa, NCG is considered as a promising material for high performance NEM devices. The high performance is highlighted for the NCG switches, e.g. low pull-in voltage integration of graphene due to the potential lower cost and better process control. We report a simple, direct deposition of nanocrystalline graphene (NCG) on insulating substrates via catalyst-free plasma-enhanced chemical vapor deposition at relatively low temperature of ~800 °C. The parametric study of the process conditions that we conducted reveals the deposition mechanism and allows us to grow high quality films. Based on such film, we demonstrate the fabrication of a large-scale array of nanoelectromechanical (NEM) switches using regular thin film process techniques, with no transfer required. Thanks to ultra-low thickness, good uniformity, and high Young's modulus of ~0.86 TPa, NCG is considered as a promising material for high performance NEM devices. The high performance is highlighted for the NCG switches, e.g. low pull-in voltage information (ESI) available. See DOI: 10.1039/c6nr00253f

  13. Nanocrystalline magnetic alloys and ceramics

    Indian Academy of Sciences (India)

    Ultrafine particles of both ferro- and ferrimagnetic systems show superparamagnetic behaviour at room temperature. Coercivity ( H c ) and maximum energy product ( B H ) max of the magnetic particles can be changed by controlling their sizes. The present paper reviews all these aspects in the case of nanocrystalline ...

  14. Automatic Data Logging and Quality Analysis System for Mobile Devices

    Directory of Open Access Journals (Sweden)

    Yong-Yi Fanjiang

    2017-01-01

    Full Text Available The testing phase of mobile device products includes two important test projects that must be completed before shipment: the field trial and the beta user trial. During the field trial, the product is certified based on its integration and stability with the local operator’s system, and, during the beta user trial, the product is certified by multiple users regarding its daily use, where the goal is to detect and solve early problems. In the traditional approach used to issue returns, testers must log into a web site, fill out a problem form, and then go through a browser or FTP to upload logs; however, this is inconvenient, and problems are reported slowly. Therefore, we propose an “automatic logging analysis system” (ALAS to construct a convenient test environment and, using a record analysis (log parser program, automate the parsing of log files and have questions automatically sent to the database by the system. Finally, the mean time between failures (MTBF is used to establish measurement indicators for the beta user trial.

  15. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    Science.gov (United States)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

  16. New nanocrystalline solar cells; Les nouvelles cellules solaires nanocristallines

    Energy Technology Data Exchange (ETDEWEB)

    Gratzel, M. [Ecole Polytechnique Federale, Lab. de Photonique et Interfaces, Lausanne (Switzerland)

    2007-05-15

    Learning from the concepts used by green plants, we have developed a new photovoltaic device which achieves very efficient light harvesting by a molecular sensitizer grafted onto a nanocrystalline semiconductor oxide film of very high internal surface area. In this way it is possible to convert visible light to electric current with an external quantum yield close to 100%. The confirmed overall efficiency for producing electricity from sunlight is 11.1%. Due to their wide range of possible applications, their environmental compatibility, as well as the simplicity and low cost of production, these devices are credible candidates to contribute to large scale electric power production from solar energy. (authors)

  17. Correlation between marketing strategy, product quality and promotion on the mobile devices market in Serbia

    Directory of Open Access Journals (Sweden)

    Bakator Mihalj

    2016-01-01

    Full Text Available This paper examines the correlation between promotion as a marketing mix instrument, product quality and marketing strategy on the mobile devices market. The research paper consists of four sections. Each section determines the key factors of the main subject's elements. The research makes analysis of the influence of promotional activities on consumer behavior. It was conducted via survey questions. The questions referred to mobile device brands, user satisfactory rates and other parameters in the Republic of Serbia. The aim was to define the impact of promotional activities on consumer choice when purchasing a mobile device. In addition, the product quality and marketing strategies of top mobile device brands are also taken into consideration. Observational statements are made based on statistical evidence from the completed research surveys.

  18. Quality Control Method for a Micro-Nano-Channel Microfabricated Device

    Science.gov (United States)

    Grattoni, Alessandro; Ferrari, Mauro; Li, Xuewu

    2012-01-01

    A variety of silicon-fabricated devices is used in medical applications such as drug and cell delivery, and DNA and protein separation and analysis. When a fluidic device inlet is connected to a compressed gas reservoir, and the outlet is at a lower pressure, a gas flow occurs through the membrane toward the outside. The method relies on the measurement of the gas pressure over the elapsed time inside the upstream and downstream environments. By knowing the volume of the upstream reservoir, the gas flow rate through the membrane over the pressure drop can be calculated. This quality control method consists of measuring the gas flow through a device and comparing the results with a standard curve, which can be obtained by testing standard devices. Standard devices can be selected through a variety of techniques, both destructive and nondestructive, such as SEM, AFM, and standard particle filtration.

  19. ISO 13485 a complete guide to quality management in the medical device industry

    CERN Document Server

    Abuhav, Itay

    2011-01-01

    Although complex and lengthy, the process of certification for the ISO 13485 can be easily mastered using the simple method outlined in ISO 13485: A Complete Guide to Quality Management in the Medical Device Industry. Written by an experienced industry professional, this practical book provides a complete guide to the ISO 13485 Standard certification for medical device manufacturing. Filled with examples drawn from the author's experience and spanning different sectors and fields of the medical device industry, the book translates the extra ordinary requirements and objectives of the standard

  20. Processing of Nanocrystalline Nitrides and Oxide Composites

    National Research Council Canada - National Science Library

    Ying, Jackie

    1998-01-01

    We have recently begun to investigate the chemical composition, specifically oxygen contamination, and sintering behavior of the nanocrystalline aluminum nitride synthesized in the forced flow reactor...

  1. TO EVALUATION TEST OF QUALITY OF MAGNETIC FLUIDS FOR MAGNETOFLUID DEVICES

    Directory of Open Access Journals (Sweden)

    V. G. Bashtovoi

    2016-01-01

    Full Text Available Magnetic fluid is a colloid of magnetic nanoparticles. Using of magnetic fluids in technical devices demands applying of strong non-uniform magnetic fields for a long time. One of the most widespread magnetic fluid devices are magnetic fluid seals of mobile shafts, magnetic fluid supports, bearings, acceleration and angle of inclination gauges, devices for information input in the computer and etc. These devices demand high quality of used fluids. Processes of magnetophoresis and Brownian diffusion in magnetic fluid lead to concentration of magnetic particles in the areas with higher intensity of magnetic field and increase of fluid magnetization in these areas. A local change of particles concentration in the fluid leads to variation of its physical properties. Formation of aggregates from the particles and the further stratification of magnetic fluid, up to its destruction, may be the most serious consequence of redistribution of concentration of magnetic particles. These factors lead to variation of parameters of magnetic fluid devices; cause disturbance of their normal operation and even failure. Therefore, the consistent, high quality magnetic fluids which are not subject to fast stratification in a non-uniform magnetic field are necessary for effective work of the devices. The procedure of evaluation test of quality of magnetic fluids is proposed in this paper. The test is based on studying of influence of processes of magnetophoresis and Brownian diffusion of magnetic particles in magnetic fluid on the forces acting on the volume of fluid in an external non-uniform magnetic field. The procedure is developed on the basis of analysis of magnetic force variation in time under the action of non-uniform field of permanent magnets. Methods of determination of stability of magnetic fluid, known at present, demand rather complicated equipment and laborious and complex investigations. Proposed procedure can be used as an express method for

  2. Effect of a vaginal device on quality of life with urinary stress incontinence

    DEFF Research Database (Denmark)

    Sander, P; Thyssen, H; Lose, G

    1999-01-01

    OBJECTIVE: To assess the effect of a vaginal device (Continence Guard) on urine leakage and quality of life. METHODS: Fifty-five women with stress incontinence participated in a 3-month study. They were assessed by the Incontinence Impact Questionnaire, two incontinence-related quality-of-life...... of urinary stress incontinence. An incontinence-specific, rather than a generic, quality-of-life questionnaire was important in assessing treatment outcomes....... questions, a generic quality-of-life questionnaire (Short Form-36), two 24-hour home pad weighing tests, a 2-day voiding diary, uroflowmetry, urine cultures, and a questionnaire about subjective effectiveness of the device. RESULTS: Forty-one (74.5%) women completed the study. Estimated on an intent...

  3. Nanocrystalline silicon in biological studies

    Czech Academy of Sciences Publication Activity Database

    Fučíková, A.; Valenta, J.; Pelant, Ivan; Kůsová, Kateřina; Březina, Vítězslav

    2011-01-01

    Roč. 8, č. 3 (2011), s. 1093-1096 ISSN 1862-6351 R&D Projects: GA AV ČR KAN400100701; GA AV ČR(CZ) IAA101120804; GA MŠk LC510; GA ČR GD202/09/H041 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z60870520 Keywords : nanocrystalline * silicon * biocompatibility * quantum dot * fluorescence label Subject RIV: BM - Solid Matter Physics ; Magnetism

  4. Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

    Science.gov (United States)

    Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

    2010-01-01

    Introduction Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning. PMID:19695725

  5. A Novel Pseudo-PMOS Integrated ISFET Device for Water Quality Monitoring

    Directory of Open Access Journals (Sweden)

    Pawan Whig

    2013-01-01

    Full Text Available The paper presents a performance analysis of novel CMOS Integrated pseudo-PMOS ISFET (PP-ISFET having zero static power dissipation. The main focus is on simulation of power and performance analysis along with the comparison with existing devices, which is used for water quality monitoring. The conventional devices, generally used, consume high power and are not stable for long term monitoring. The conventional device has the drawbacks of low value of slew rate, high power consumption, and nonlinear characteristics, but in this novel design, due to zero static power, less load capacitance on input signals, faster switching, fewer transistors, and higher circuit density, the device exhibits a better slew rate and piecewise linear characteristics and is seen consuming low power of the order of 30 mW. The proposed circuit reduces total power consumption per cycle, increases the speed of operation, is fairly linear, and is simple to implement.

  6. Photoluminescence of nanocrystalline ZnS thin film grown by sol-gel method.

    Science.gov (United States)

    Anila, E I; Safeera, T A; Reshmi, R

    2015-03-01

    Nano and polycrystalline ZnS thin films play a crucial role in photovoltaic technology and optoelectronic devices. In this work, we report the photoluminescence (PL) characterization of nanocrystalline ZnS thin films synthesized by dip coating method. The PL spectra exhibit broad nature with multiple emission peaks which are due to the different defect levels in the prepared film.

  7. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Taking a cubic unit cell or a regular polyhedron unit cell of nanocrystalline material, the volume fraction of each ... The present article reviews the present states of understanding in these aspects of nanocrystalline materials. ..... Calculations based on the equation of state show 37% reduction in tetragonal shear modulus of ...

  8. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique ...

  9. Variations in daily quality assurance dosimetry from device levelling, feet position and backscatter material

    International Nuclear Information System (INIS)

    Ceylan, Abdurrahman; Cullen, Ashley; Butson, Martin; Yu, Peter K.N.; Alnawaf, Hani

    2012-01-01

    Daily quality assurance procedures are an essential part of radiotherapy medical physics. Devices such as the Sun Nuclear, DQA3 are effective tools for analysis of daily dosimetry including flatness, symmetry, energy, field size and central axis radiation dose measurement. The DQA3 can be used on the treatment couch of the linear accelerator or on a dedicated table/bed for superficial and orthovoltage x-ray machines. This device is levelled using its dedicated feet. This work has shown that depending on the quantity of backscatter material behind the DQA3 device, the position of the levelling feet can affect the measured central axis dose by up to 1.8 % (250 kVp and 6 MV) and that the introduction of more backscatter material behind the DQA3 can lead to up to 7.2 % (6 MV) variations in measured central axis dose. In conditions where no backscatter material is present, dose measurements can vary up to 1 %. As such this work has highlighted the need to keep the material behind the DQA3 device constant as well as maintaining the accuracy of the feet position on the device to effectively measure the most accurate daily constancy achievable. Results have also shown that variations in symmetry and energy calculations of up to 1 % can occur if the device is not levelled appropriately. As such, we recommend the position of the levelling feet on the device be as close as possible to the device so that a constant distance is kept between the DQA3 and the treatment couch and thus minimal levelling variations also occur. We would also recommend having no extra backscattering material behind the DQA3 device during use to minimise any variations which might occur from these backscattering effects.

  10. Nanocrystalline diamond--an excellent platform for life science applications.

    Science.gov (United States)

    Kloss, Frank R; Najam-Ul-Haq, Muhammed; Rainer, Matthias; Gassner, Robert; Lepperdinger, Günter; Huck, Christian W; Bonn, Günther; Klauser, Frederik; Liu, Xianjie; Memmel, Norbert; Bertel, Erminald; Garrido, Jose A; Steinmüller-Nethl, Doris

    2007-12-01

    Nanocrystalline diamond (NCD) has recently been successfully utilized in a variety of life science applications. NCD films are favorable and salubrious substrates for cells during cultivation. Therefore NCD has also been employed in tissue engineering strategies. NCD as reported in this contribution was grown by means of a modified hot-filament chemical vapor deposition technique, which results in less than 3% sp2-hybridization and yields grain sizes of 5-20 nm. After production the NCD surface was rather hydrophobic, however it could be efficiently refined to exhibit more hydrophilic properties. Changing of the surface structure was found to be an efficient means to influence growth and differentiation capacity of a variety of cells. The particular needs for any given cell type has to be proven empirically. Yet flexible features of NCD appear to be superior to plastic surfaces which can be hardly changed in quality. Besides its molecular properties, crystal structural peculiarities of NCD appear to influence cell growth as well. In our attempt to facilitate, highly specialized applications in biomedicine, we recently discovered that growth factors can be tightly bound to NCD by mere physisorption. Hence, combination of surface functionalization together with further options to coat NCD with any kind of three-dimensional structure opens up new avenues for many more applications. In fact, high through-put protein profiling of early disease stages may become possible from serum samples, because proteins bound to NCD can now be efficiently analyzed by MALDI/TOF-MS. Given these results, it is to be presumed that the physical properties and effective electrochemical characteristics of NCD will allow tailoring devices suitable for many more diagnostic as well as therapeutic applications.

  11. A portable device for detecting fruit quality by diffuse reflectance Vis/NIR spectroscopy

    Science.gov (United States)

    Sun, Hongwei; Peng, Yankun; Li, Peng; Wang, Wenxiu

    2017-05-01

    Soluble solid content (SSC) is a major quality parameter to fruit, which has influence on its flavor or texture. Some researches on the on-line non-invasion detection of fruit quality were published. However, consumers desire portable devices currently. This study aimed to develop a portable device for accurate, real-time and nondestructive determination of quality factors of fruit based on diffuse reflectance Vis/NIR spectroscopy (520-950 nm). The hardware of the device consisted of four units: light source unit, spectral acquisition unit, central processing unit, display unit. Halogen lamp was chosen as light source. When working, its hand-held probe was in contact with the surface of fruit samples thus forming dark environment to shield the interferential light outside. Diffuse reflectance light was collected and measured by spectrometer (USB4000). ARM (Advanced RISC Machines), as central processing unit, controlled all parts in device and analyzed spectral data. Liquid Crystal Display (LCD) touch screen was used to interface with users. To validate its reliability and stability, 63 apples were tested in experiment, 47 of which were chosen as calibration set, while others as prediction set. Their SSC reference values were measured by refractometer. At the same time, samples' spectral data acquired by portable device were processed by standard normalized variables (SNV) and Savitzky-Golay filter (S-G) to eliminate the spectra noise. Then partial least squares regression (PLSR) was applied to build prediction models, and the best predictions results was achieved with correlation coefficient (r) of 0.855 and standard error of 0.6033° Brix. The results demonstrated that this device was feasible to quantitatively analyze soluble solid content of apple.

  12. A portable device for rapid nondestructive detection of fresh meat quality

    Science.gov (United States)

    Lin, Wan; Peng, Yankun

    2014-05-01

    Quality attributes of fresh meat influence nutritional value and consumers' purchasing power. In order to meet the demand of inspection department for portable device, a rapid and nondestructive detection device for fresh meat quality based on ARM (Advanced RISC Machines) processor and VIS/NIR technology was designed. Working principal, hardware composition, software system and functional test were introduced. Hardware system consisted of ARM processing unit, light source unit, detection probe unit, spectral data acquisition unit, LCD (Liquid Crystal Display) touch screen display unit, power unit and the cooling unit. Linux operating system and quality parameters acquisition processing application were designed. This system has realized collecting spectral signal, storing, displaying and processing as integration with the weight of 3.5 kg. 40 pieces of beef were used in experiment to validate the stability and reliability. The results indicated that prediction model developed using PLSR method using SNV as pre-processing method had good performance, with the correlation coefficient of 0.90 and root mean square error of 1.56 for validation set for L*, 0.95 and 1.74 for a*,0.94 and 0.59 for b*, 0.88 and 0.13 for pH, 0.79 and 12.46 for tenderness, 0.89 and 0.91 for water content, respectively. The experimental result shows that this device can be a useful tool for detecting quality of meat.

  13. Powder-based synthesis of nanocrystalline material components for structural application. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ilyuschenko, A.F.; Ivashko, V.S.; Okovity, V.A. [Powder Metallurgy Research Inst., Minsk (Belarus)] [and others

    1998-12-01

    Hydroxiapate spray coatings and substrates for implant production as well as multilayered metal ceramic coatings from nanocrystalline materials are a subject of the investigation. The work aims at the improvement of quality of said objects. This study has investigated the processes of hydroxiapatite powder production. Sizes, shapes and relief of initial HA powder surface are analyzed using SEM and TEM. Modes of HA plasma spraying on a substrate from titanium and associated compositions of traditional and nanocrystalline structure are optimized. The quality of the sprayed samples are studied using X-ray phase analysis and metallographic analysis. The results of investigations of bioceramic coating spraying on titanium are theoretically generalized, taking into account obtained experimental data. The results of investigations of ion-beam technology are presented for spraying multilayered coatings consisting of alternating metal-ceramic layers of nanocrystalline structure.

  14. Dynamic recovery in nanocrystalline Ni

    International Nuclear Information System (INIS)

    Sun, Z.; Van Petegem, S.; Cervellino, A.; Durst, K.; Blum, W.; Van Swygenhoven, H.

    2015-01-01

    The constant flow stress reached during uniaxial deformation of electrodeposited nanocrystalline Ni reflects a quasi-stationary balance between dislocation slip and grain boundary (GB) accommodation mechanisms. Stress reduction tests allow to suppress dislocation slip and bring recovery mechanisms into the foreground. When combined with in situ X-ray diffraction it can be shown that grain boundary recovery mechanisms play an important role in producing plastic strain while hardening the microstructure. This result has a significant consequence for the parameters of thermally activated glide of dislocations, such as athermal stress and activation volume, which are traditionally derived from stress/strain rate change tests

  15. Advanced Photon Source insertion device field quality and multipole error specification

    International Nuclear Information System (INIS)

    Chae, Yong-Chul; Decker, G.

    1995-01-01

    The Advanced Photon Source (APS) storage ring is a 7-GeV light source with forty straight sections. Intense x-ray beams will be delivered by insertion devices installed in these straight sections. Installation of insertion devices in the APS storage ring produces several effects which can degrade overall performance. Rigid ring performance requirements exist which can be used to set limits on insertion device field quality, i.e. the first- and second-field integrals of the transverse magnetic field. Individual multipole error specifications can be determined by considering the lifetime of the beam. For nominal operation of the APS storage ring, the vertical aperture corresponding to a 10-hour lifetime is approximately 3.35 mm, which limits the level of multipole error. We find that the skew-octupole error has the most significant effect on the reduction of the aperture; the reasons are discussed in this paper

  16. Automatic analysis of image quality control for Image Guided Radiation Therapy (IGRT) devices in external radiotherapy

    International Nuclear Information System (INIS)

    Torfeh, Tarraf

    2009-01-01

    On-board imagers mounted on a radiotherapy treatment machine are very effective devices that improve the geometric accuracy of radiation delivery. However, a precise and regular quality control program is required in order to achieve this objective. Our purpose consisted of developing software tools dedicated to an automatic image quality control of IGRT devices used in external radiotherapy: 2D-MV mode for measuring patient position during the treatment using high energy images, 2D-kV mode (low energy images) and 3D Cone Beam Computed Tomography (CBCT) MV or kV mode, used for patient positioning before treatment. Automated analysis of the Winston and Lutz test was also proposed. This test is used for the evaluation of the mechanical aspects of treatment machines on which additional constraints are carried out due to the on-board imagers additional weights. Finally, a technique of generating digital phantoms in order to assess the performance of the proposed software tools is described. Software tools dedicated to an automatic quality control of IGRT devices allow reducing by a factor of 100 the time spent by the medical physics team to analyze the results of controls while improving their accuracy by using objective and reproducible analysis and offering traceability through generating automatic monitoring reports and statistical studies. (author) [fr

  17. The effective quality assurance for image guided device using the AMC G-Box

    International Nuclear Information System (INIS)

    Kim, Chong Mi

    2014-01-01

    According to the rapid increase recently in image-guided radiation therapy, It is necessary to control of the image guidance system completely. In particular for the main subject to the accuracy of image guided radiation therapy device to be done essentially the quality assurance. We made efficient phantom in AMC for the management of the accurate and efficient. By setting up of five very important as a quality assurance inventory of the Image guidance system, we made (AMC G-Box) phantom for quality assurance efficient and accurate. Quality assurance list were the Iso-center align, the real measurement, the center align of four direction, the accuracy of table movement and the reproducibility of Hounsfield Unit. The rectangular phantom; acrylic with a thickness of 1 cm to 10 cm × 10 cm × 10 cm was inserted the three materials with different densities respectively for measure the CBCT HU. The phantom was to perform a check of consistency centered by creating a marker that indicates the position of the center fixed. By performing the quality assurance using the phantom of existing, comparing the resulting value to the different resulting value using the AMC G-Box, experiment was analyzed time and problems. Therapy equipment was used Varian device. It was measured twice at 1-week intervals. When implemented quality assurance of an image guidance system using AMC G-Box and a phantom existing has been completed, the quality assurance result is similar in 0.2 mm ± 0.1. In the case of the conventional method, it was 45 minutes at 30 minutes. When using AMC G-Box, it takes 20 minutes 15 minutes, and declined to 50% of the time. The consistency and accurate of image guidance system tend to decline using device. Therefore, We need to perform thoroughly on the quality assurance related. It needs to be checked daily to consistency check especially. When using the AMC G-Box, It is possible to enhance the accuracy of the patient care and equipment efficiently performing

  18. Real-time computer treatment of THz passive device images with the high image quality

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

    We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

  19. Comparison of MLC error sensitivity of various commercial devices for VMAT pre-treatment quality assurance.

    Science.gov (United States)

    Saito, Masahide; Sano, Naoki; Shibata, Yuki; Kuriyama, Kengo; Komiyama, Takafumi; Marino, Kan; Aoki, Shinichi; Ashizawa, Kazunari; Yoshizawa, Kazuya; Onishi, Hiroshi

    2018-03-03

    The purpose of this study was to compare the MLC error sensitivity of various measurement devices for VMAT pre-treatment quality assurance (QA). This study used four QA devices (Scandidos Delta4, PTW 2D-array, iRT systems IQM, and PTW Farmer chamber). Nine retrospective VMAT plans were used and nine MLC error plans were generated for all nine original VMAT plans. The IQM and Farmer chamber were evaluated using the cumulative signal difference between the baseline and error-induced measurements. In addition, to investigate the sensitivity of the Delta4 device and the 2D-array, global gamma analysis (1%/1, 2%/2, and 3%/3 mm), dose difference (1%, 2%, and 3%) were used between the baseline and error-induced measurements. Some deviations of the MLC error sensitivity for the evaluation metrics and MLC error ranges were observed. For the two ionization devices, the sensitivity of the IQM was significantly better than that of the Farmer chamber (P < 0.01) while both devices had good linearly correlation between the cumulative signal difference and the magnitude of MLC errors. The pass rates decreased as the magnitude of the MLC error increased for both Delta4 and 2D-array. However, the small MLC error for small aperture sizes, such as for lung SBRT, could not be detected using the loosest gamma criteria (3%/3 mm). Our results indicate that DD could be more useful than gamma analysis for daily MLC QA, and that a large-area ionization chamber has a greater advantage for detecting systematic MLC error because of the large sensitive volume, while the other devices could not detect this error for some cases with a small range of MLC error. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  20. Research on installation quality inspection system of high voltage customer metering device based on image recognition

    Science.gov (United States)

    He, Bei; Yang, Fu-li; Tao, Xue-dan; Chang, Shi-liang; Wu, Kang

    2017-11-01

    With the rapid development of the scale of the power grid, the site construction and the operations environment is more widespread and more complex. The installation work of the high-voltage customer metering device is heavy, which is not standardized. In addition, managers supervise the site construction progress only through the person in charge of each work phrase. It is inefficient and difficult to control the multi-team and multi-unit cross work. Therefore, it is necessary to establish a scientific system to detect the quality of installation and management practices to standardize installation work of the metering device. Based on the research of image recognition and target detection system, this paper presents a high-voltage customer metering device installation quality inspection system based on digital image processing, image feature extraction and SVM classification decision. The experimental results show that the proposed scheme is feasible. And it can be used to accurately extract the metering components in the image, which can be also accurately and quickly classified. Our method is of great significance for the implementation and monitoring of the power system in installation and specification

  1. Improvement in chest compression quality using a feedback device (CPRmeter): a simulation randomized crossover study.

    Science.gov (United States)

    Buléon, Clément; Parienti, Jean-Jacques; Halbout, Laurent; Arrot, Xavier; De Facq Régent, Hélène; Chelarescu, Dan; Fellahi, Jean-Luc; Gérard, Jean-Louis; Hanouz, Jean-Luc

    2013-10-01

    Cardiac arrest survival depends on celerity and efficiency of life support action. Guidelines emphasized the chest compression (CC) quality and feedback devices are encouraged. The purpose is to study the impact of the CPRmeter feedback device on resuscitation performed by untrained rescuers. This is a prospective randomized crossover study on manikins (Resusci Anne). One hundred and forty four students inexperienced in cardiopulmonary resuscitation representing untrained rescuers were included. Participants performed 2 minutes of CC without interruption with (group G) or without (group B) feedback. Four months passed between the 2 crossover phases to avoid resilience effect. Data collected by the CPRmeter device were: CC rate, depth and release. Efficient CC rate ([simultaneous and correct CC rate, depth and release] primary outcome) (absolute difference [95% CI]) was significantly improved in group G (71%) compared to group B (26%; [45 {36-55}]; P 38 mm) was significantly improved in group G (85%) compared to group B (43%; [42 {33-52}]; P < .0001). Adequate CC rate (90-120/min) was significantly improved in group G (81%) compared to group B (56%; [25 {15-35}]; P < .0001). The average CC rate and depth in group G were significantly less dispersed around the mean compared to group B (test of variance P < .007; P < .015 respectively). The use of the CPRmeter significantly improved CC quality performed by students inexperienced in cardiopulmonary resuscitation. © 2013.

  2. Synthesis and Processing of Nanocrystalline Aluminum Nitride

    OpenAIRE

    Duarte, Matthew Albert

    2016-01-01

    Synthesis, processing and characterization of nanocrystalline aluminum nitride has been systematically studied. Non-carbon based gas nitridation was used to reduce nanocrystalline γ-alumina, having a grain size of ~80 nm. Single phase aluminum nitride powder was obtained at firing temperatures of 1200°C. Further processing of AlN powders was performed by CAPAD (Current Activated Pressure Assisted Densification) to obtain dense single phase aluminum nitride. Dense bulk aluminum nitride was ob...

  3. Improving the quality of CVD graphene-based devices: synthesis, transfer, fabrication and measurement

    Science.gov (United States)

    Wang, Junjie; Wang, Bei; Skinner, Anna; Zhu, Jun

    2013-03-01

    Graphene synthesized by chemical vapor deposition (CVD) is potentially useful in a wide range of electronic and optoelectronic applications. In order to obtain CVD-graphene based devices with performance comparable to their exfoliated counterparts, improvement needs to be made on the synthesis and transfer of graphene, as well as device fabrication and measurement techniques. Here we report on a low-pressure growth procedure, which successfully suppresses the growth of multilayer patches, resulting in large-scale single-layer graphene production. By following the etching of the copper substrate with a HCl/H2O2 cleaning step similar to the RCA-2 procedure used in Silicon industry, metal particle contamination is reduced. By applying the gate voltage in pulse, we eliminate the hysteresis commonly observed in the transfer curve of graphene field effect transistors. This allows us to accurately determine the charge neutrality point and carrier mobility of the device. We are able to achieve high-quality CVD-graphene devices with average carrier mobility of 7,000 cm2V-1s-1.

  4. Effect of mandibular advancement device on sleep bruxism score and sleep quality.

    Science.gov (United States)

    Solanki, Nehal; Singh, Balendra Pratap; Chand, Pooran; Siddharth, Ramashankar; Arya, Deeksha; Kumar, Lakshya; Tripathi, Suryakant; Jivanani, Hemant; Dubey, Abhishek

    2017-01-01

    The use of mandibular advancement devices (MADs) in the treatment of sleep bruxism is gaining widespread importance. However, the effects of MADs on sleep bruxism scores, sleep quality, and occlusal force are not clear. The purpose of this clinical study was to analyze the effect of MADs on sleep bruxism scores, sleep quality, and occlusal force. This uncontrolled before and after study enrolled 30 participants with sleep bruxism. Outcomes assessed were sleep quality, sleep bruxism scores (sleep bruxism bursts and sleep bruxism episodes/hour), and occlusal force before and after 15 and 30 days of using a MAD. Sleep bruxism scores were assessed by ambulatory polysomnography and sleep quality by using the Pittsburgh sleep quality index (PSQI). Occlusal force was recorded by using a digital gnathodynamometer in the first molar region on both sides. Statistical analysis was done by 1-factor repeated measures ANOVA (α=.05). Statistically significant reductions in sleep bruxism bursts/h, sleep bruxism episodes/h, and PSQI scores were found after 15 and 30 days of using a MAD (Psleep bruxism scores, sleep quality, and reduction in occlusal force in sleep bruxism participants after using MADs. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  5. QUALITY OF SAMPLE SIZE ESTIMATION IN TRIALS OF MEDICAL DEVICES: HIGH-RISK DEVICES FOR NEUROLOGICAL CONDITIONS AS EXAMPLE.

    Science.gov (United States)

    Olberg, Britta; Perleth, Matthias; Felgentraeger, Katja; Schulz, Sandra; Busse, Reinhard

    2017-01-01

    The aim of this study was to assess the quality of reporting sample size calculation and underlying design assumptions in pivotal trials of high-risk medical devices (MDs) for neurological conditions. Systematic review of research protocols for publicly registered randomized controlled trials (RCTs). In the absence of a published protocol, principal investigators were contacted for additional data. To be included, trials had to investigate a high-risk MD, registered between 2005 and 2015, with indications stroke, headache disorders, and epilepsy as case samples within central nervous system diseases. Extraction of key methodological parameters for sample size calculation was performed independently and peer-reviewed. In a final sample of seventy-one eligible trials, we collected data from thirty-one trials. Eighteen protocols were obtained from the public domain or principal investigators. Data availability decreased during the extraction process, with almost all data available for stroke-related trials. Of the thirty-one trials with sample size information available, twenty-six reported a predefined calculation and underlying assumptions. Justification was given in twenty and evidence for parameter estimation in sixteen trials. Estimates were most often based on previous research, including RCTs and observational data. Observational data were predominantly represented by retrospective designs. Other references for parameter estimation indicated a lower level of evidence. Our systematic review of trials on high-risk MDs confirms previous research, which has documented deficiencies regarding data availability and a lack of reporting on sample size calculation. More effort is needed to ensure both relevant sources, that is, original research protocols, to be publicly available and reporting requirements to be standardized.

  6. Microstructure factor and mechanical and electronic properties of hydrogenated amorphous and nanocrystalline silicon thin-films for microelectromechanical systems applications

    International Nuclear Information System (INIS)

    Mouro, J.; Gualdino, A.; Chu, V.; Conde, J. P.

    2013-01-01

    Thin-film silicon allows the fabrication of MEMS devices at low processing temperatures, compatible with monolithic integration in advanced electronic circuits, on large-area, low-cost, and flexible substrates. The most relevant thin-film properties for applications as MEMS structural layers are the deposition rate, electrical conductivity, and mechanical stress. In this work, n + -type doped hydrogenated amorphous and nanocrystalline silicon thin-films were deposited by RF-PECVD, and the influence of the hydrogen dilution in the reactive mixture, the RF-power coupled to the plasma, the substrate temperature, and the deposition pressure on the structural, electrical, and mechanical properties of the films was studied. Three different types of silicon films were identified, corresponding to three internal structures: (i) porous amorphous silicon, deposited at high rates and presenting tensile mechanical stress and low electrical conductivity, (ii) dense amorphous silicon, deposited at intermediate rates and presenting compressive mechanical stress and higher values of electrical conductivity, and (iii) nanocrystalline silicon, deposited at very low rates and presenting the highest compressive mechanical stress and electrical conductivity. These results show the combinations of electromechanical material properties available in silicon thin-films and thus allow the optimized selection of a thin silicon film for a given MEMS application. Four representative silicon thin-films were chosen to be used as structural material of electrostatically actuated MEMS microresonators fabricated by surface micromachining. The effect of the mechanical stress of the structural layer was observed to have a great impact on the device resonance frequency, quality factor, and actuation force

  7. CIEL*a*b* color space predictive models for colorimetry devices--analysis of perfume quality.

    Science.gov (United States)

    Korifi, Rabia; Le Dréau, Yveline; Antinelli, Jean-François; Valls, Robert; Dupuy, Nathalie

    2013-01-30

    Color perception plays a major role in the consumer evaluation of perfume quality. Consumers need first to be entirely satisfied with the sensory properties of products, before other quality dimensions become relevant. The evaluation of complex mixtures color presents a challenge even for modern analytical techniques. A variety of instruments are available for color measurement. They can be classified as tristimulus colorimeters and spectrophotometers. Obsolescence of the electronics of old tristimulus colorimeter arises from the difficulty in finding repair parts and leads to its replacement by more modern instruments. High quality levels in color measurement, i.e., accuracy and reliability in color control are the major advantages of the new generation of color instrumentation, the integrating sphere spectrophotometer. Two models of spectrophotometer were tested in transmittance mode, employing the d/0° geometry. The CIEL(*)a(*)b(*) color space parameters were measured with each instrument for 380 samples of raw materials and bases used in the perfume compositions. The results were graphically compared between the colorimeter device and the spectrophotometer devices. All color space parameters obtained with the colorimeter were used as dependent variables to generate regression equations with values obtained from the spectrophotometers. The data was statistically analyzed to create predictive model between the reference and the target instruments through two methods. The first method uses linear regression analysis and the second method consists of partial least square regression (PLS) on each component. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Water quality control device and water quality control method for reactor primary coolant system

    International Nuclear Information System (INIS)

    Wada, Yoichi; Ibe, Eishi; Watanabe, Atsushi.

    1995-01-01

    The present invention is suitable for preventing defects due to corrosion of structural materials in a primary coolant system of a BWR type reactor. Namely, a concentration measuring means measures the concentration of oxidative ingredients contained in a reactor water. A reducing electrode is disposed along a reactor water flow channel in the primary coolant system and reduces the oxidative ingredients. A reducing counter electrode is disposed along the reactor water flow channel in the primary coolant system, and electrically connected to the reducing electrode. The reactor structural materials are used as a reference electrode providing a reference potential to the reducing electrode and the reducing counter electrode. A potential control means controls the potential of the reducing electrode relative to the reference potential based on the signals from the concentration measuring means. A stable reference potential in a region where an effective oxygen concentration is stable can be obtained irrespective of the change of operation conditions by using the reactor structural materials disposed to a boiling region in the reactor core as a reference electrode. As a result, the water quality can be controlled at high accuracy. (I.S.)

  9. A new hyperspectral imaging based device for quality control in plastic recycling

    Science.gov (United States)

    Bonifazi, G.; D'Agostini, M.; Dall'Ava, A.; Serranti, S.; Turioni, F.

    2013-05-01

    The quality control of contamination level in the recycled plastics stream has been identified as an important key factor for increasing the value of the recycled material by both plastic recycling and compounder industries. Existing quality control methods for the detection of both plastics and non-plastics contaminants in the plastic waste streams at different stages of the industrial process (e.g. feed, intermediate and final products) are currently based on the manual collection from the stream of a sample and on the subsequent off-line laboratory analyses. The results of such analyses are usually available after some hours, or sometimes even some days, after the material has been processed. The laboratory analyses are time-consuming and expensive (both in terms of equipment cost and their maintenance and of labour cost).Therefore, a fast on-line assessment to monitor the plastic waste feed streams and to characterize the composition of the different plastic products, is fundamental to increase the value of secondary plastics. The paper is finalized to describe and evaluate the development of an HSI-based device and of the related software architectures and processing algorithms for quality assessment of plastics in recycling plants, with particular reference to polyolefins (PO). NIR-HSI sensing devices coupled with multivariate data analysis methods was demonstrated as an objective, rapid and non-destructive technique that can be used for on-line quality and process control in the recycling process of POs. In particular, the adoption of the previous mentioned HD&SW integrated architectures can provide a solution to one of the major problems of the recycling industry, which is the lack of an accurate quality certification of materials obtained by recycling processes. These results could therefore assist in developing strategies to certify the composition of recycled PO products.

  10. Meta-Review of the Quantity and Quality of Evidence for Knee Arthroplasty Devices.

    Directory of Open Access Journals (Sweden)

    Anna R Gagliardi

    Full Text Available Some cardiovascular devices are licensed based on limited evidence, potentially exposing patients to devices that are not safe or effective. Research is needed to ascertain if the same is true of other types of medical devices. Knee arthroplasty is a widely-used surgical procedure yet implant failures are not uncommon. The purpose of this study was to characterize available evidence on the safety and effectiveness of knee implants.A review of primary studies included in health technology assessments (HTA on total (TKA and unicompartmental knee arthroplasty (UKA was conducted. MEDLINE, EMBASE, CINAHL, Cochrane Library and Biotechnology & BioEngineering Abstracts were searched from 2005 to 2014, plus journal tables of contents and 32 HTA web sites. Patients were aged 18 and older who underwent primary TKA or UKA assessed in cohort or randomized controlled studies. Summary statistics were used to report study characteristics.A total of 265 eligible primary studies published between 1986 and 2014 involving 59,217 patients were identified in 10 HTAs (2 low, 7 moderate, 1 high risk of bias. Most evaluated TKA (198, 74.5%. The quality of evidence in primary studies was limited. Most studies were industry-funded (23.8% or offered no declaration of funding or conflict of interest (44.9%; based on uncontrolled single cohorts (58.5%, enrolled fewer than 100 patients (66.4%, and followed patients for 2 years or less (UKA: single cohort 29.8%, comparative cohort 16.7%, randomized trial 25.0%; TKA: single cohort 25.0%, comparative cohort 31.4%, randomized trial 48.6%. Furthermore, most devices were evaluated in only one study (55.3% TKA implants, 61.1% UKA implants.Patients, physicians, hospitals and payers rely on poor-quality evidence to support decisions about knee implants. Further research is needed to explore how decisions about the use of devices are currently made, and how the evidence base for device safety and effectiveness can be strengthened.

  11. The Development of a Quality Management Framework for Evaluating Medical Device Reprocessing Practice in Healthcare Facilities.

    Science.gov (United States)

    Lorv, Bailey; Horodyski, Robin; Welton, Cynthia; Vail, John; Simonetto, Luca; Jokanovic, Danilo; Sharma, Richa; Mahoney, Angela Rea; Savoy-Bird, Shay; Bains, Shalu

    2017-01-01

    There is increasing awareness of the importance of medical device reprocessing (MDR) for the provision of safe patient care. Although industry service standards are available to guide MDR practices, there remains a lack of published key performance indicators (KPIs) and targets that are necessary to evaluate MDR quality for feedback and improvement. This article outlines the development of an initial framework that builds on established guidelines and includes service standards, KPIs and targets for evaluating MDR operations. This framework can support healthcare facilities in strengthening existing practices and enables a platform for collaboration towards better MDR performance management.

  12. Low-cost high-quality crystalline germanium based flexible devices

    KAUST Repository

    Nassar, Joanna M.

    2014-06-16

    High performance flexible electronics promise innovative future technology for various interactive applications for the pursuit of low-cost, light-weight, and multi-functional devices. Thus, here we show a complementary metal oxide semiconductor (CMOS) compatible fabrication of flexible metal-oxide-semiconductor capacitors (MOSCAPs) with high-κ/metal gate stack, using a physical vapor deposition (PVD) cost-effective technique to obtain a high-quality Ge channel. We report outstanding bending radius ~1.25 mm and semi-transparency of 30%.

  13. Cardiovascular magnetic resonance imaging in patients with cardiac implantable electronic devices: a device-dependent imaging strategy for improved image quality.

    Science.gov (United States)

    Hilbert, Sebastian; Jahnke, Cosima; Loebe, Susanne; Oebel, Sabrina; Weber, Alexander; Spampinato, Ricardo; Richter, Sergio; Doering, Michael; Bollmann, Andreas; Sommer, Philipp; Hindricks, Gerhard; Paetsch, Ingo

    2017-10-18

    To prospectively determine evaluability of routine cardiovascular magnetic resonance (CMR) diagnostic modules in a referral population of implanted rhythm device all-comers, and to establish a device-dependent CMR imaging strategy to achieve optimal image quality. One hundred and twenty-eight patients with cardiac implantable electronic devices [insertable cardiac monitoring system, n = 14; implantable loop-recorder, n = 21; pacemaker, n = 31; implantable cardioverter-defibrillator (ICD), n = 50; and cardiac resynchronization therapy defibrillator (CRT-D), n = 12] underwent clinically indicated CMR at 1.5 T. CMR protocols were tailored to the clinical indication and consisted of cine, perfusion, T1-/T2-weighted, late-gadolinium enhancement (LGE), 3D angiographic, and post-contrast cine spoiled gradient echo (SGE) scans. Image quality was determined using a 4-grade visual score per myocardial segment. Segmental evaluability was strongly influenced by device type and location with the highest proportion of non-diagnostic images encountered in the presence of ICD/CRT-D systems. Cine steady-state free-precession (SSFP) imaging was found to be mostly non-diagnostic in ICD/CRT-D patients, but a significant improvement of image quality was demonstrated when using SGE sequences with a further incremental improvement post-contrast resulting in an overall four-fold higher likelihood of achieving good image quality. LGE scans were found to be non-diagnostic in about one-third of left-ventricular segments of ICD/CRT-D patients but were artefact-free in > 94% for all other device types. Device type and location constitute the main independent predictors of CMR image quality and thus, need to be considered during protocol adaptation. Most notably, post-contrast SGE cine imaging proved superior to conventionally used SSFP sequences. Thus, following the proposed device-dependent CMR imaging strategy, diagnostic image quality can be achieved in the

  14. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Science.gov (United States)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  15. The use of an electronic portal imaging device for exit dosimetry and quality control measurements

    International Nuclear Information System (INIS)

    Kirby, Michael C.; Williams, Peter C.

    1995-01-01

    Purpose: To determine ways in which electronic portal imaging devices (EPIDs) could be used to (a) measure exit doses for external beam radiotherapy and (b) perform quality control checks on linear accelerators. Methods and Materials: When imaging, our fluoroscopic EPID adjusts the gain, offset, and frame acquisition time of the charge coupled device (CCD) camera automatically, to allow for the range of photon transmissions through the patient, and to optimize the signal-to-noise ratio. However, our EPID can be programmed to act as an integrating dosemeter. EPID dosemeter measurements were made for 20 MV photons, for different field sizes and thicknesses of unit density phantom material placed at varying exit surface to detector distances. These were compared with simultaneous Silicon diode exit dose measurements. Our exit dosimetry technique was verified using an anthropomorphic type phantom, and some initial measurements have been made for patients treated with irregularly shaped 20 MV x-ray fields. In this dosimetry mode, our EPID was also used to measure certain quality control parameters, x-ray field flatness, and the verification of segmented intensity modulated field prescriptions. Results: Configured for dosimetry, our EPID exhibited a highly linear response, capable of resolving individual monitor units. Exit doses could be measured to within about 3% of that measured using Silicon diodes. Field flatness was determined to within 1.5% of Farmer dosemeter measurements. Segmented intensity modulated fields can be easily verified. Conclusions: Our EPID has the versatility to assess a range of parameters pertinent to the delivery of high quality, high precision radiotherapy. When configured appropriately, it can measure exit doses in vivo, with reasonable accuracy, perform certain quick quality control checks, and analyze segmented intensity modulated treatment fields

  16. Quality assurance procedure for functional performance of industrial gamma radiography exposure devices

    International Nuclear Information System (INIS)

    Kannan, R.; Yadav, R.K.; Rajoo Kumar; Bhatt, B.C.; Sivaraman, G.; Nandkumar, A.N.

    2003-05-01

    An Industrial Gamma Radiography Exposure Device (IGRED) consists of various moving parts and accessories and wear and tear take place often. This may increase the possibility of radiation incidents and result in avoidable radiation exposure. Quality assurance tests of the equipment for functional performance plays a major role in ensuring that the exposure device and its accessories perform their intended functions and satisfy radiation safety requirements to avert potential exposures to operators. Therefore, in India it is practiced as mandatory requirement that each IGRED is tested for its functional performance and only after ascertaining that features of operational safety are satisfactory, loading of the source into the radiography exposure device can be permitted. This procedure which is being. practiced since the late 1970s, has contributed significantly towards the safe use of IGREDs and minimising the occurrence of radiation accidents. The purpose of this document is to highlight the importance of periodic functional performance check of each IGRED as per the checklist for the testing procedures. It is also proposed to entrust this activity to accredited laboratories, which have the necessary infrastructure to carry out this activity. The prerequisites for accreditation of such laboratories to carry out this activity and the testing procedures to be adopted for checking the functional performance of various models of IGREDs used in this country are given in this report. (author)

  17. Guideline for Technical Quality Assurance (TQA) of Ultrasound devices (B-Mode) - Version 1.0 (July 2012)

    NARCIS (Netherlands)

    Kollmann, C.; Korte, C.L. de; Dudley, N.J.; Gritzmann, N.; Martin, K.; Evans, D.H.

    2012-01-01

    The Technical Quality Assurance group was initiated by the EFSUMB Board in 2007 and met firstly in 2008 to discuss and evaluate methods and procedures published for performing technical quality assurance for diagnostic ultrasound devices. It is the aim of this group of experts to advise the EFSUMB

  18. Structural elucidation of nanocrystalline biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Maltsev, S.

    2008-10-23

    Bone diseases, such as osteoporosis and osteoarthritis, are the second most prevalent health problem worldwide. In Germany approximately 5 millions people are affected by arthritis. Investigating biomineralization processes and bone molecular structure is of key importance for developing new drugs for preventing and healing bone diseases. Nuclear magnetic resonance (NMR) was the primary technique used due to its advantages in characterising poorly ordered and disordered materials. Compared to all the diffraction techniques that widely applied in structural investigations, the usefulness of NMR is independent of long range molecular order. This makes NMR an outstanding technique for studies of complex/amorphous materials. Conventional NMR experiments (single pulse, spin-echo, cross polarization (CP), etc.) as well as their modifications and high-end techniques (2D HETCOR, REDOR, etc.) were used in this work. Combining the contributions from different techniques enhances the information content of the investigations and can increase the precision of the overall conclusions. Also XRD, TEM and FTIR were applied to different extent in order to get a general idea of nanocrystalline hydroxyapatite crystallite structure. Results: - A new approach named 'Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments' has been developed for measuring the transferred I spin magnetization from abundant nuclei, which is normally lost when detecting the S spin magnetization. - A detailed investigation of nanocrystalline hydroxyapatite core was made to prove that proton environment of the phosphates units and phosphorus environment of hydroxyl units are the same as in highly crystalline hydroxyapatite sample. - Using XRD it was found that the surface of the hydroxyapatite nanocrystals is not completely disordered, as it was suggested before, but resembles the hydroxyapatite structure with HPO{sub 4}{sup 2-} (and some CO{sub 3}{sup

  19. Assessment of image quality in x-ray radiography imaging using a small plasma focus device

    International Nuclear Information System (INIS)

    Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

    2014-01-01

    This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm. - Highlights: • We investigated a small plasma focus as pulsed x-ray source for radiography applications. • The image quality was studied by several parameters such as image contrast, LSF and MTF. • The x-ray source focal spot was obtained to be ∼0.6 mm using the penumbra imaging method. • The x-ray dose measurement showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. • The profiles of LSF and MTF showed that the cut-off frequency is about 1.5 cycles/mm

  20. Evaluation of electronic imaging device portal 'Portal Dosimetry' in quality control in intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Watanabe, Erika Yumi

    2010-01-01

    In this paper we present commissioning testing and evaluation of the use of Varian's portal dosimetry in the quality assurance of intensity-modulated radiotherapy. The commissioning tests were performed to characterize the portal dosimetry in terms dosimetric and to assess the its possible application in radiotherapy. These tests demonstrated that portal dosimetry has all the characteristics to be used for dosimetry in radiotherapy such as linear response with dose, the independence of dose rate, reproducibility, and others. The evaluation of the use of portal dosimetry in quality control of IMRT was performed in two steps: assessing the ability of the device to detect errors deliberately introduced in simple and complex fluences. Errors of known magnitude were introduced in certain areas of fluences and was carried out quality control of these fluences with portal dosimetry and three dosimetric systems: ionization chamber, film and array of ionization chambers. The data obtained from the portal were compared with those of other devices and all were able to identify errors introduced satisfactorily, the values, normalized to the original fluence, obtained with the portal dosimetry were similar to the ionization chamber and the array of ion chambers (seven29) and differing in up to 2% of the values obtained with the films. The fluences measured with the portal dosimetry were evaluated both quantitatively and qualitatively. The index of the gamma function provided by software analysis of portal dosimetry showed no defined rules of behavior in relation to the errors introduced and for this reason the qualitative analysis has proved indispensable in cases evaluated. (author)

  1. Image quality assessment of three limited field-of-view cone-beam computed tomography devices in endodontics

    International Nuclear Information System (INIS)

    Tran, Michel

    2015-01-01

    Since the beginning of Cone Beam Computed Tomography (CBCT) in dento-maxillo-facial radiology, many CBCT devices with different technical aspects and characteristics were produced. Technical variations between CBCT and acquisition settings could involve image quality differences. In order to compare the performance of three limited field-of-view CBCT devices, an objective and subjective evaluation of image quality was carried out using an ex-vivo phantom, which combines both diagnostic and technical features. A significant difference in image quality was found between the five acquisition protocols of the study. (author) [fr

  2. Characterization and Application of Colloidal Nanocrystalline Materials for Advanced Photovoltaics

    Science.gov (United States)

    Bhandari, Khagendra P.

    Solar energy is Earth's primary source of renewable energy and photovoltaic solar cells enable the direct conversion of sunlight into electricity. Crystalline silicon solar cells and modules have dominated photovoltaic technology from the beginning and they now constitute more than 90% of the PV market. Thin film (CdTe and CIGS) solar cells and modules come in second position in market share. Some organic, dye-sensitized and perovskite solar cells are emerging in the market but are not yet in full commercial scale. Solar cells made from colloidal nanocrystalline materials may eventually provide both low cost and high efficiency because of their promising properties such as high absorption coefficient, size tunable band gap, and quantum confinement effect. It is also expected that the greenhouse gas emission and energy payback time from nanocrystalline solar PV systems will also be least compared to all other types of PV systems mainly due to the least embodied energy throughout their life time. The two well-known junction architectures for the fabrication of quantum dot based photovoltaic devices are the Schottky junction and heterojunction. In Schottky junction cells, a heteropartner semiconducting material is not required. A low work function metal is used as the back contact, a transparent conducting layer is used as the front contact, and the layer of electronically-coupled quantum dots is placed between these two materials. Schottky junction solar cells explain the usefulness of nanocrystalline materials for high efficiency heterojunction solar cells. For heterojunction devices, n-type semiconducting materials such as ZnO , CdS or TiO2 have been used as suitable heteropartners. Here, PbS quantum dot solar cells were fabricated using ZnO and CdS semiconductor films as window layers. Both of the heteropartners are sputter-deposited onto TCO coated glass substrates; ZnO was deposited with the substrate held at room temperature and for CdS the substrate was at 250

  3. An approach for assessment of water quality using semipermeable membrane devices (SPMDs) and bioindicator tests

    Science.gov (United States)

    Petty, J.D.; Jones, S.B.; Huckins, J.N.; Cranor, W.L.; Parris, J.T.; McTague, T.B.; Boyle, T.P.

    2000-01-01

    As an integral part of our continued development of water quality assessment approaches, we combined integrative sampling, instrumental analysis of widely occurring anthropogenic contaminants, and the application of a suite of bioindicator tests as a specific part of a broader survey of ecological conditions, species diversity, and habitat quality in the Santa Cruz River in Arizona, USA. Lipid-containing semipermeable membrane devices (SPMDs) were employed to sequester waterborne hydrophobic chemicals. Instrumental analysis and a suite of bioindicator tests were used to determine the presence and potential toxicological relevance of mixtures of bioavailable chemicals in two major water sources of the Santa Cruz River. The SPMDs were deployed at two sites; the effluent weir of the International Wastewater Treatment Plant (IWWTP) and the Nogales Wash. Both of these systems empty into the Santa Cruz River and the IWWTP effluent is a potential source of water for a constructed wetland complex. Analysis of the SPMD sample extracts revealed the presence of organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). The bioindicator tests demonstrated increased liver enzyme activity, perturbation of neurotransmitter systems and potential endocrine disrupting effects (vitellogenin induction) in fish exposed to the extracts. With increasing global demands on limited water resources, the approach described herein provides an assessment paradigm applicable to determining the quality of water in a broad range of aquatic systems.

  4. Combustion synthesis of bulk nanocrystalline iron alloys

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2016-02-01

    Full Text Available The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  5. Rapid phase synthesis of nanocrystalline cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavel, T., E-mail: shanmugavelnano@gmail.com [Department of Physics, Paavai Engineering College, Namakkal -637018 (India); Raj, S. Gokul [Department of Physics, Vel Tech University, Avadi, Chennai - 600 062 (India); Rajarajan, G. [Department of Physics, Mahendra Engineering College, Mallasamudram -637503 (India); Kumar, G. Ramesh [Department of Physics, University College of Engineering, Anna University Chennai, Arni- 632317 (India)

    2014-04-24

    Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe{sub 2}O{sub 4}) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeability's than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the bulk nature of materials synthesized by other methods.

  6. Optimised design and development of a bio-medical healthcare device through quality function deployment (QFD).

    Science.gov (United States)

    Sharma, Jitendra

    2012-01-01

    Technology is major stimulus for change and is imbibed in various forms; especially in the field of medical devices and bio-medical instruments used in life and death situations. Cardiotocograph (CTG), a foetal heart rate and uterine contraction monitoring and measurement machine, is a valuable tool in the process of childbirth. The Quality Function Deployment (QFD) is an engineering technique with the number one priority being to satisfy the customer. The aim of using QFD in this paper is to highlight the limitations and complexities of the present instrument. The paper attempts to first discuss out the operational details of the instrument along with a brief review of the relevant literature. Following this, its functional analysis is carried out through QFD - a TQM tool. The resultant outcome enlists CTG functions with their Raw Weight and Priority Score. A detailed theoretical analysis of results pinpoints basic functional limitation of exiting machine.

  7. Quality control in mammography: development of a practical device for kVp measurement

    International Nuclear Information System (INIS)

    Schiabel, H.; Frere, A.F.; Andreeta, J.P.

    1990-01-01

    The development of quality control programs for radiographic systems is important due to various factors which influence in obtaining good image contrast. In mammographic systems one of the parameters which particularly requires great attention is controlling the electric potential applied to a X-ray tube (i.e, kVp) which determines the beam energy conditions. The mammographic system is the most convenient for premature breast cancer detection, presenting however, serious problems in obtaining clear contrast, once the energy range which makes possible the differentiation among the soft tissues involved is very restrict. Hence this work presents the development of a device to provide the kVp measurement of mammographic systems. The instrument make uses of the scintillation detection process and has a simple operation mode, providing imediate output signal viewed on displays. (author) [pt

  8. Perovskite Solar Cells: From the Atomic Level to Film Quality and Device Performance.

    Science.gov (United States)

    Saliba, Michael; Correa-Baena, Juan-Pablo; Grätzel, Michael; Hagfeldt, Anders; Abate, Antonio

    2018-03-01

    Organic-inorganic perovskites have made tremendous progress in recent years due to exceptional material properties such as high panchromatic absorption, charge carrier diffusion lengths, and a sharp optical band edge. The combination of high-quality semiconductor performance with low-cost deposition techniques seems to be a match made in heaven, creating great excitement far beyond academic ivory towers. This is particularly true for perovskite solar cells (PSCs) that have shown unprecedented gains in efficiency and stability over a time span of just five years. Now there are serious efforts for commercialization with the hope that PSCs can make a major impact in generating inexpensive, sustainable solar electricity. In this Review, we will focus on perovskite material properties as well as on devices from the atomic to the thin film level to highlight the remaining challenges and to anticipate the future developments of PSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Magnetization loss of nanocrystalline soft magnets

    International Nuclear Information System (INIS)

    Flohrer, Sybille; Herzer, Giselher

    2009-01-01

    FeCuNbSiB-ribbons with optimized nanocrystalline microstructure possess a unique combination of near-zero magnetostriction, high saturation induction and low magnetization losses. Due to the absence of distinct intrinsic anisotropies, the magnetization curve can be adjusted by field-annealing to square or flat shape. It is well known that excess losses are an important loss component of soft magnets with square hysteresis loop. Yet, even cores of flat type loop can show significant excess losses. The paper reviews the loss mechanisms for excess losses in nanocrystalline soft magnets on the basis of Kerr-microscopy observation and loss theory and compares it to amorphous materials.

  10. Boron-doped nanocrystalline silicon thin films for solar cells

    International Nuclear Information System (INIS)

    Fathi, E.; Vygranenko, Y.; Vieira, M.; Sazonov, A.

    2011-01-01

    This article reports on the structural, electronic, and optical properties of boron-doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films. The films were deposited by plasma-enhanced chemical vapour deposition (PECVD) at a substrate temperature of 150 deg. C. Crystalline volume fraction and dark conductivity of the films were determined as a function of trimethylboron-to-silane flow ratio. Optical constants of doped and undoped nc-Si:H were obtained from transmission and reflection spectra. By employing p + nc-Si:H as a window layer combined with a p' a-SiC buffer layer, a-Si:H-based p-p'-i-n solar cells on ZnO:Al-coated glass substrates were fabricated. Device characteristics were obtained from current-voltage and spectral-response measurements.

  11. Feasibility study on an integrated AEC-grid device for the optimization of image quality and exposure dose in mammography

    Science.gov (United States)

    Kim, Kyo-Tae; Yun, Ryang-Young; Han, Moo-Jae; Heo, Ye-Ji; Song, Yong-Keun; Heo, Sung-Wook; Oh, Kyeong-Min; Park, Sung-Kwang

    2017-10-01

    Currently, in the radiation diagnosis field, mammography is used for the early detection of breast cancer. In addition, studies are being conducted on a grid to produce high-quality images. Although the grid ratio of the grid, which affects the scattering removal rate, must be increased to improve image quality, it increases the total exposure dose. While the use of automatic exposure control is recommended to minimize this problem, existing mammography equipment, unlike general radiography equipment, is mounted on the back of a detector. Therefore, the device is greatly affected by the detector and supporting device, and it is difficult to control the exposure dose. Accordingly, in this research, an integrated AEC-grid device that simultaneously performs AEC and grid functions was used to minimize the unnecessary exposure dose while removing scattering, thereby realizing superior image quality.

  12. Nanocrystalline diamond films for biomedical applications

    DEFF Research Database (Denmark)

    Pennisi, Cristian Pablo; Alcaide, Maria

    2014-01-01

    performance of nanocrystalline diamond films is reviewed from an application-specific perspective, covering topics such as enhancement of cellular adhesion, anti-fouling coatings, non-thrombogenic surfaces, micropatterning of cells and proteins, and immobilization of biomolecules for bioassays. In order...

  13. Synthesis and characterization of nanocrystalline zinc ferrite

    DEFF Research Database (Denmark)

    Jiang, J.S.; Yang, X.L.; Gao, L.

    1999-01-01

    Nanocrystalline zinc ferrite powders with a partially inverted spinel structure were synthesized by high-energy ball milling in a closed container at ambient temperature from a mixture of alpha-Fe2O3 and ZnO crystalline powders in equimolar ratio. From low-temperature and in-field Mossbauer...

  14. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    International Nuclear Information System (INIS)

    Mecartnery, Martha; Graeve, Olivia; Patel, Maulik

    2017-01-01

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  15. Chemical vapor deposition of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Vyrovets, I.I.; Gritsyna, V.I.; Dudnik, S.F.; Opalev, O.A.; Reshetnyak, O.M.; Strel'nitskij, V.E.

    2008-01-01

    The brief review of the literature is devoted to synthesis of nanocrystalline diamond films. It is shown that the CVD method is an effective way for deposition of such nanostructures. The basic technological methods that allow limit the size of growing diamond crystallites in the film are studied.

  16. Synthesis of nanocrystalline fluorinated hydroxyapatite by ...

    Indian Academy of Sciences (India)

    Fluorinated hydroxyapatite, (FHA, Ca10(PO4)6(OH)2-F), possesses higher corrosion resistance in biofluids than pure HA and reduces the risk of dental caries. The present work deals with the synthesis of nanocrystalline FHAs by microwave processing. The crystal size and morphology of the nanopowders were ...

  17. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

    2017-05-25

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  18. Characterisation of interfaces in nanocrystalline palladium

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Alternatively, it is possible to calculate power spectrum from each of the nanocrystalline grains in images scanned or recorded online using a framestore. Peak detection algorithms can then be applied to detect peak positions corresponding to the lattice periodicity in the grain. Advantages are that the process can be made ...

  19. Phonon density of states in nanocrystalline Fe

    Indian Academy of Sciences (India)

    Abstract. The Born–von Karman model is used to calculate phonon density of states (DOS) of nanocrystalline bcc Fe. It is found that there is an anisotropic stiffening in the interatomic force constants and hence there is shrinking in the nearest-neighbour distances in the nanophase. This leads to additional vibrational modes ...

  20. Characterization of nanocrystalline silicon germanium film and ...

    African Journals Online (AJOL)

    The nanocrystalline silicon-germanium films (Si/Ge) and Si/Ge nanotubes have low band gaps and high carrier mobility, thus offering appealing potential for absorbing gas molecules. Interaction between hydrogen molecules and bare as well as functionalized Si/Ge nanofilm and nanotube was investigated using Monte ...

  1. Characterization of nanocrystalline cadmium telluride thin films ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 2. Characterization of nanocrystalline ... Structural, electrical and optical characteristics of CdTe thin films prepared by a chemical deposition method, successive ionic layer adsorption and reaction (SILAR), are described. For deposition of CdTe thin films, ...

  2. Structural, optical and photoluminescence study of nanocrystalline ...

    Indian Academy of Sciences (India)

    Undoped SnO2 thin films prepared by spray pyrolysis method reveal polycrystalline nature with prominent peaks along (110), (101) and (211) planes. All the films are nanocrystalline with particle size lying in the range of 3.14–8.6 nm calculated by DS formula. Orientation along plane (200) decreases continuously as molar ...

  3. Effect of first-flush device, roofing material, and antecedent dry days on water quality of harvested rainwater.

    Science.gov (United States)

    Gikas, Georgios D; Tsihrintzis, Vassilios A

    2017-09-01

    Two rainwater harvesting systems, which included first-flush diversion devices, connected to the roofs of two adjacent buildings, were monitored for water quality. The roofs were constructed from different materials, i.e., one roof was covered with ceramic tiles and the other was made of concrete. Water quality samples from the two storage tanks and the first-flush devices were collected and analyzed, showing satisfactory water quality in the tanks for residential non-potable use, while the water in the first-flush device was of poorer quality. Between the two collection surfaces, statistically significant differences were found only in the concentrations of NH 4 -N, orthophosphate, and Ca 2+ . Total coliforms were detected in both the storage tanks and the first-flush devices, indicating that disinfection of harvested rainwater may be necessary if it is collected for potable uses. Finally, first-flush water quality was related to antecedent dry days, showing that when the number of dry days increased, the accumulation of materials on the concrete roof was reduced while it was increased on the ceramic tile roof. This is attributed to the fact that the concrete roof is nearly horizontal (very slightly sloped), and the wind action easily removes various materials which accumulate on it.

  4. The progress of nanocrystalline hydride electrode materials

    International Nuclear Information System (INIS)

    Jurczyk, M.

    2004-01-01

    This paper reviews research at the Institute of Materials Science and Engineering, Poznan University of Technology, on the synthesis of nanocrystalline hydride electrode materials. Nanocrystalline materials have been synthesized by mechanical alloying (MA) followed by annealing. Examples of the materials include TiFe - , ZrV 2- , LaNi 5 and Mg 2 Ni-type phases. Details on the process used and the enhancement of properties due to the nanoscale structures are presented. The synthesized alloys were used as negative electrode materials for Ni-MH battery. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. For example, it was found that the respective replacement of Fe in TiFe by Ni and/or by Cr, Co, Mo improved not only the discharge capacity but also the cycle life of these electrodes. The hydrogen storage properties of nanocrystalline ZrV 2 - and LaNi 5 -type powders prepared by mechanical alloying and annealing show no big difference with those of melt casting (polycrystalline) alloys. On the other hand, a partial substitution of Mg by Mn or Al in Mg 2 Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. In the case of Mg 2 Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline TiFe - , ZrV 2 - and LaNi 5 -type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, has been successful. (authors)

  5. Alloy-dependent deformation behavior of highly ductile nanocrystalline AuCu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lohmiller, Jochen [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Spolenak, Ralph [Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Gruber, Patric A., E-mail: patric.gruber@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany)

    2014-02-10

    Nanocrystalline thin films on compliant substrates become increasingly important for the development of flexible electronic devices. In this study, nanocrystalline AuCu thin films on polyimide substrate were tested in tension while using a synchrotron-based in situ testing technique. Analysis of X-ray diffraction profiles allowed identifying the underlying deformation mechanisms. Initially, elastic and microplastic deformation is observed, followed by dislocation-mediated shear band formation, and eventually macroscopic crack formation. Particularly the influence of alloy composition, heat-treatment, and test temperature were investigated. Generally, a highly ductile behavior is observed. However, high Cu concentrations, annealing, and/or large plastic strains lead to localized deformation and hence reduced ductility. On the other hand, enhanced test temperature allows for a delocalized deformation and extended ductility.

  6. Co+ -ion implantation induced doping of nanocrystalline CdS thin films: structural, optical, and vibrational properties

    International Nuclear Information System (INIS)

    Chandramohan, S.; Sarangi, S.N.; Majumder, S.; Som, T.; Kanjilal, A.; Sathyamoorthy, R.

    2009-01-01

    Full text: Transition metal (Mn, Fe, Co and Ni) doped CdS nanostructures and nanocrystalline thin films have attracted much attention due to their anticipated applications in magneto-optical, non-volatile memory and future spintronics devices. Introduction of impurities in substitutional positions is highly desirable for such applications. Ion implantation is known to provide many advantages over conventional methods for efficient doping and possibility of its seamless integration with device processing steps. It is not governed by equilibrium thermodynamics and offers the advantages of high spatial selectivity and to overcome the solubility limits. In this communication, we report on modifications of structural morphological, optical, and vibrational properties of 90 keV Co + -ion implanted CdS thin films grown by thermal evaporation. Co + -ion implantation was performed in the fluence range of 0.1-3.6x10 16 ions cm -2 These fluences correspond to Co concentration in the range of 0.34-10.8 at % at the peak position of profile. Implantation was done at an elevated temperature of 573 K in order to avoid amorphization and to enhance the solubility of Co ions in the CdS lattice. Films were characterized by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), optical absorption, and micro-Raman spectroscopy. Implantation does not lead to any secondary phase formation either in the form of impurity or the metallic clusters. However, implantation improves the crystalline quality of the samples and leads to supersaturation of Co ions in the CdS lattice. Thus, nanocrystalline CdS thin films can be considered as a good radiation- resistant material, which can be employed for prolonged use in solar cells for space applications. The optical band gap is found to decrease systematically with increasing ion fluence from 2.39 to 2.28 eV. Implantation leads to agglomeration of grains and a systematic increase in the surface roughness. Both GAXRD and micro

  7. n-Type phosphorus-doped nanocrystalline diamond: electrochemical and in situ Raman spectroelectrochemical study

    OpenAIRE

    Zivcova, Z. Vlckova; Frank, O.; Drijkoningen, Sien; Haenen, Ken; Mortet, Vincent; Kavan, L.

    2016-01-01

    Electrochemical and in situ Raman spectroelectrochemical characterization of n-type phosphorus-doped nanocrystalline diamond (P-NCD) is carried out. The P-NCD films are grown by microwave plasma enhanced chemical vapour deposition and doped with phosphorus at a concentration of 10 000 ppm in the gas phase. Micro-Raman spectroscopy determines the film quality (presence of graphitic or amorphous phases). All electrochemical measurements are performed in aqueous 0.5 M H2SO4 electrolyte solution....

  8. Possible way for increasing the quality of imaging from THz passive device

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.; Deng, Chao; Zhao, Yuan-meng; Zhang, Cun-lin; Zhang, Xin

    2011-11-01

    Using the passive THz imaging system developed by the CNU-THz laboratory, we capture the passive THz image of human body with forbidden objects hidden under opaque clothes. We demonstrate the possibility of significant improving the quality of the image. Our approach bases on the application of spatial filters, developed by us for computer treatment of passive THz imaging. The THz imaging system is constructed with accordance to well known passive THz imaging principles and to the THz quasi-optical theory. It contains a scanning mechanism, which has a detector approximately with 1200μm central wavelength, a data acquisition card and a microcomputer. To get a clear imaging of object we apply a sequence of the spatial filters to the image and spectral transforms of the image. The treatment of imaging from the passive THz device is made by computer code. The performance time of treatment of the image, containing about 5000 pixels, is less than 0.1 second. To illustrate the efficiency of developed approach we detect the liquid explosive, knife, pistol and metal plate hidden under opaque clothes. The results obtained demonstrate the high efficiency of our approach for the detection and recognition of the hidden objects and are very promising for the real security application.

  9. Evaluation of working air quality by using semipermeable membrane devices. Analysis of organophosphorus pesticides.

    Science.gov (United States)

    Esteve-Turrillas, Francesc A; Pastor, Agustín; de la Guardia, Miguel

    2008-09-19

    It has been evaluated the use of semipermeable membrane devices (SPMDs) as passive samplers of organophosphorus pesticides from air, in order to determine the contamination of working environments. Additionally, the use of SPMDs as portable samplers has been also considered. The analytical methodology for the determination of diazinon, chlorpyrifos-methyl, pirimiphos-methyl, chlorpyrifos and fenthion in SPMDs exposed to contaminated air was based on microwave-assisted extraction and gas chromatography with mass spectrometry determination. Limit of detection (LOD) values from 2 to 4ngSPMD(-1) and repeatability from 2 to 7% were obtained by using the aforementioned methodology. Theoretical calculated sampling rates were employed for the estimation of the pesticide concentration in air, by using the pesticide mass retained in the deployed SPMD. The obtained LOD values, for a sampling time of 7 days, were from 1 to 2ngm(-3). The evaluation of the air quality of a pesticide laboratory with an intensive use of diazinon and chlorpyrifos has been made in order to check the operation safety conditions.

  10. Plasma-induced transformation of carbon nanotubes to nanocrystalline diamond

    International Nuclear Information System (INIS)

    Sun Litao; Gong Jinlong; Zhu Zhiyuan; Zhu Dezhang; He Suixia; Wang Zhenxia

    2004-01-01

    Structural phase transformation from multiwalled carbon nanotubes to nanocrystalline diamond by hydrogen plasma post-treatment was carried out. Ultrahigh equivalent diamond nucleation density above 10 11 nuclei/cm 2 was easily obtained. The diamond formation and growth mechanism was proposed to be the consequence of the formation of sp 3 bonded amorphous carbon clusters. The hydrogen chemisorption on curved graphite network and the energy deposited on the carbon nanotubes by continuous impingement of activated molecular or atomic hydrogen are responsible for the formation of amorphous carbon matrix. The diamond nucleates and grows in the way similar to that of diamond CVD processes on amorphous carbon films. The present method of hydrogen treatment provides a controllable way for the CVD of high quality diamond films

  11. Abrasive wear behaviour of electrodeposited nanocrystalline materials

    Science.gov (United States)

    Jeong, Daehyun

    The effect of grain size refinement on the abrasive wear behaviour of nanocrystalline Ni, Ni-P and Co electrodeposits and the critical materials properties that influence the abrasive wear resistance were studied using the Taber wear test. As the grain size of Ni decreased from 90 mum to 13 nm, the dominant abrasive wear mode changed from ploughing to cutting and the Taber wear resistance was considerably improved by the increases in hardness and surface elastic properties. The abrasive wear behaviour of Ni with various grain sizes can be described using the attack angle model, which takes into consideration the randomly dispersed Al2O3 abrasive particles in the Taber wheel with various sizes, shapes and orientations. Depending on the phosphorus content, the nickel-phosphorus (Ni-P) alloys containing up to 6 wt.% P had nanocrystalline or mixed nanocrystalline-amorphous structures and both regular and inverse Hall-Petch behaviour were observed as a result of the microstructural changes with increasing P content/decreasing grain size. The wear resistance, like hardness, followed the Hall-Petch type behaviour, demonstrating that the smallest grain size does not necessarily provide the best wear resistance. For all Ni-P alloys, the wear resistance was improved by heat treatment due to Ni3P precipitates and, for materials with high P content, nanocrystallization of the amorphous phase. For heat-treated Ni-P alloys, however, the highest hardness did not give the best wear resistance. Despite the grain size reduction of Co from 10 mum to 17 nm, there was no significant change in the wear resistance due to the unusually high degree of plastic deformation of the nanocrystalline material. In addition to hardness and surface elastic properties which are usually considered important material properties that control the abrasive wear resistance, Taber wear ductility was introduced as a new material intrinsic property which can be applied to explain abrasive wear resistance for

  12. Highway-runoff quality, and treatment efficiencies of a hydrodynamic-settling device and a stormwater-filtration device in Milwaukee, Wisconsin

    Science.gov (United States)

    Horwatich, Judy A.; Bannerman, Roger T.; Pearson, Robert

    2011-01-01

    The treatment efficiencies of two prefabricated stormwater-treatment devices were tested at a freeway site in a high-density urban part of Milwaukee, Wisconsin. One treatment device is categorized as a hydrodynamic-settling device (HSD), which removes pollutants by sedimentation and flotation. The other treatment device is categorized as a stormwater-filtration device (SFD), which removes pollutants by filtration and sedimentation. During runoff events, flow measurements were recorded and water-quality samples were collected at the inlet and outlet of each device. Efficiency-ratio and summation-of-load (SOL) calculations were used to estimate the treatment efficiency of each device. Event-mean concentrations and loads that were decreased by passing through the HSD include total suspended solids (TSS), suspended sediment (SS), total phosphorus (TP), total copper (TCu), and total zinc (TZn). The efficiency ratios for these constituents were 42, 57, 17, 33, and 23 percent, respectively. The SOL removal rates for these constituents were 25, 49, 10, 27, and 16 percent, respectively. Event-mean concentrations and loads that increased by passing through the HSD include chloride (Cl), total dissolved solids (TDS), and dissolved zinc (DZn). The efficiency ratios for these constituents were -347, -177, and 20 percent, respectively. Four constituents—dissolved phosphorus (DP), chemical oxygen demand (COD), total polycyclic aromatic hydrocarbon (PAH), and dissolved copper (DCu)—are not included in the list of computed efficiency ratio and SOL because the variability between sampled inlet and outlet pairs were not significantly different. Event-mean concentrations and loads that decreased by passing through the SFD include TSS, SS, TP, DCu, TCu, DZn, TZn, and COD. The efficiency ratios for these constituents were 59, 90, 40, 21, 66, 23, 66, and 18, respectively. The SOLs for these constituents were 50, 89, 37, 19, 60, 20, 65, and 21, respectively. Two constituents—DP and

  13. Ultrafast Terahertz Conductivity of Photoexcited Nanocrystalline Silicon

    DEFF Research Database (Denmark)

    Cooke, David; MacDonald, A. Nicole; Hryciw, Aaron

    2007-01-01

    The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a class......The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described...... by a classical Drude–Smith model, suitable for disorder-driven metal–insulator transitions. In this work, we explore the time evolution of the frequency dependent complex conductivity after optical injection of carriers on a picosecond time scale. Furthermore, we show the lifetime of photoconductivity...

  14. X-ray interference by nanocrystalline domains.

    Science.gov (United States)

    Gelisio, Luca; Scardi, Paolo

    2012-11-01

    Regular arrangement of nanocrystalline domains can introduce interference effects which alter considerably the powder diffraction pattern. Role of nanocrystal alignment (local texture) and mutual positioning are different, with the latter much more effective in controlling the interference effect. While it is demonstrated that these effects are unlikely to be observed on a conventional laboratory instrument, coherence conditions available at modern synchrotron radiation beamlines might support further investigations of interference in systems made of very fine nanocrystals.

  15. Solubility of Carbon in Nanocrystalline -Iron

    OpenAIRE

    Kirchner, Alexander; Kieback, Bernd

    2012-01-01

    A thermodynamic model for nanocrystalline interstitial alloys is presented. The equilibrium solid solubility of carbon in -iron is calculated for given grain size. Inside the strained nanograins local variation of the carbon content is predicted. Due to the nonlinear relation between strain and solubility, the averaged solubility in the grain interior increases with decreasing grain size. The majority of the global solubility enhancement is due to grain boundary enrichment however. Therefor...

  16. Nanocrystalline diamond growth on different substrates

    Czech Academy of Sciences Publication Activity Database

    Kulisch, W.; Popov, C.; Vorlíček, Vladimír; Gibson, P. N.; Favaro, G.

    2006-01-01

    Roč. 515, - (2006), s. 1005-1010 ISSN 0040-6090 Grant - others:EC Framework(XE) MEIF-CT-2004-500038; NATO(XE) CBP.EAP.CLG 981519 Institutional research plan: CEZ:AV0Z10100520 Keywords : nanocrystalline diamond * growth mechanisms * nucleation mechanisms * mechanical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.666, year: 2006

  17. Characterization of amorphous and nanocrystalline carbon films

    International Nuclear Information System (INIS)

    Chu, Paul K.; Li Liuhe

    2006-01-01

    Amorphous and nanocrystalline carbon films possess special chemical and physical properties such as high chemical inertness, diamond-like properties, and favorable tribological proprieties. The materials usually consist of graphite and diamond microstructures and thus possess properties that lie between the two. Amorphous and nanocrystalline carbon films can exist in different kinds of matrices and are usually doped with a large amount of hydrogen. Thus, carbon films can be classified as polymer-like, diamond-like, or graphite-like based on the main binding framework. In order to characterize the structure, either direct bonding characterization methods or the indirect bonding characterization methods are employed. Examples of techniques utilized to identify the chemical bonds and microstructure of amorphous and nanocrystalline carbon films include optical characterization methods such as Raman spectroscopy, Ultra-violet (UV) Raman spectroscopy, and infrared spectroscopy, electron spectroscopic and microscopic methods such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, transmission electron microscopy, and electron energy loss spectroscopy, surface morphology characterization techniques such as scanning probe microscopy (SPM) as well as other characterization methods such as X-ray reflectivity and nuclear magnetic resonance. In this review, the structures of various types of amorphous carbon films and common characterization techniques are described

  18. Sintering and deformation of nanocrystalline ceramics

    International Nuclear Information System (INIS)

    Hahn, H.; Averback, R.S.; Hofler, H.J.; Logas, J.

    1991-01-01

    Nanocrystalline ceramics have been produced by the method of inert gas condensation of ultra-small particles and in situ consolidation. Sintering characteristics and microstructural parameter such as grain size, porosity and pore size distributions have been investigated by a variety of techniques, including: X-ray diffraction, gravimetry, nitrogen adsorption, scanning electron microscopy and small angle neutron scattering. In pure TiO 2 , the sintering temperatures are drastically lowered compared to conventional ceramics, however, extensive grain growth occurs before full densification is achieved. High density, nanocrystalline ceramics can be prepared by pressure assisted sintering, doping and additions of second phases. High temperature microhardness and creep deformation in compression were measured and it was found that creep processes occur at lower temperatures than in ceramics with larger grain sizes. Nanocrystalline TiO 2 with densities >99% can be deformed plastically without fracture at temperatures below half the melting point. The total strains exceed 0.6 at strain rates as high as 10 -3 s -l . The stress exponent of the strain rate, n, is approximately 3 and the grain size dependence is G -q with q in the range of 1-1.5. In this paper it is concluded that the creep deformation occurs by an interface reaction controlled mechanism

  19. Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-11-01

    Full Text Available Recent developments in biomineralization have already demonstrated that nanosized particles play an important role in the formation of hard tissues of animals. Namely, the basic inorganic building blocks of bones and teeth of mammals are nanodimensional and nanocrystalline calcium orthophosphates (in the form of apatites of a biological origin. In mammals, tens to hundreds nanocrystals of a biological apatite were found to be combined into self-assembled structures under the control of various bioorganic matrixes. In addition, the structures of both dental enamel and bones could be mimicked by an oriented aggregation of nanosized calcium orthophosphates, determined by the biomolecules. The application and prospective use of nanodimensional and nanocrystalline calcium orthophosphates for a clinical repair of damaged bones and teeth are also known. For example, a greater viability and a better proliferation of various types of cells were detected on smaller crystals of calcium orthophosphates. Thus, the nanodimensional and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the field of hard tissue engineering starting from bone repair and augmentation to the controlled drug delivery devices. This paper reviews current state of knowledge and recent developments of this subject starting from the synthesis and characterization to biomedical and clinical applications. More to the point, this review provides possible directions of future research and development.

  20. YBa2Cu3O7 thin films on nanocrystalline diamond films for HTSC bolometer

    Science.gov (United States)

    Cui, G.; Beetz, C. P., Jr.; Boerstler, R.; Steinbeck, J.

    1993-01-01

    Superconducting YBa2Cu3O(7-x) films on nanocrystalline diamond thin films have been fabricated. A composite buffer layer system consisting of diamond/Si3N4/YSZ/YBCO was explored for this purpose. The as-deposited YBCO films were superconducting with Tc of about 84 K and a relatively narrow transition width of about 8 K. SEM cross sections of the films showed very sharp interfaces between diamond/Si3N4 and between Si3N4/YSZ. The deposited YBCO film had a surface roughness of about 1000 A, which is suitable for high-temperature superconductive (HTSC) bolometer fabrication. It was also found that preannealing of the nanocrystalline diamond thin films at high temperature was very important for obtaining high-quality YBCO films.

  1. YBa2Cu3O7 thin films on nanocrystalline diamond films for HTSC bolometer

    Science.gov (United States)

    Cui, G.; Beetz, C. P., Jr.; Boerstler, R.; Steinbeck, J.

    1993-03-01

    Superconducting YBa2Cu3O(7-x) films on nanocrystalline diamond thin films have been fabricated. A composite buffer layer system consisting of diamond/Si3N4/YSZ/YBCO was explored for this purpose. The as-deposited YBCO films were superconducting with Tc of about 84 K and a relatively narrow transition width of about 8 K. SEM cross sections of the films showed very sharp interfaces between diamond/Si3N4 and between Si3N4/YSZ. The deposited YBCO film had a surface roughness of about 1000 A, which is suitable for high-temperature superconductive (HTSC) bolometer fabrication. It was also found that preannealing of the nanocrystalline diamond thin films at high temperature was very important for obtaining high-quality YBCO films.

  2. Properties of CdTe nanocrystalline thin films grown on different substrates by low temperature sputtering

    International Nuclear Information System (INIS)

    Chen Huimin; Guo Fuqiang; Zhang Baohua

    2009-01-01

    CdTe nanocrystalline thin films have been prepared on glass, Si and Al 2 O 3 substrates by radio-frequency magnetron sputtering at liquid nitrogen temperature. The crystal structure and morphology of the films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The XRD examinations revealed that CdTe films on glass and Si had a better crystal quality and higher preferential orientation along the (111) plane than the Al 2 O 3 . FESEM observations revealed a continuous and dense morphology of CdTe films on glass and Si substrates. Optical properties of nanocrystalline CdTe films deposited on glass substrates for different deposited times were studied.

  3. Deposition, microstructure, and properties of nanocrystalline Ti(C,O,N) coatings

    Science.gov (United States)

    Ruppi, S.; Larsson, A.

    2003-01-01

    Chemical vapor deposition of Ti(C,N) coatings from the TiCl4- CH3CN- N2-H2 system on cemented carbide substrates was studied. The morphology and grain size of the coatings were modified using carbon monoxide (CO). Transmission electron microscopy confirmed that grain refinement of the Ti(C,N) coatings could be obtained by means of CO doping and nanocrystalline coatings were obtained at CO levels exceeding 6%. CO doping resulted in the incorporation of oxygen in the structure, but no segregation of oxygen to grain boundaries was observed. The coatings appeared to be of homogeneous composition even at the highest CO levels. Both improved coating hardness and surface quality were obtained with decreasing grain size. However, the coatings exhibited clearly lower crater wear resistance in the nanograined region. This was explained by an increased tendency for grain-boundary sliding in the nanocrystalline coatings leading to more pronounced plastic deformation.

  4. An evaluation of the quality of evidence available to inform current bone conducting hearing device national policy.

    Science.gov (United States)

    Mandavia, R; Carter, A W; Haram, N; Mossialos, E; Schilder, A G M

    2017-10-01

    In 2016, NHS England published the commissioning policy on Bone Conducting Hearing Devices (BCHDs). This policy was informed by updated evidence on the clinical and cost-effectiveness of BCHDs as well as by the 2013 Bone Anchored Hearing Aid (BAHA) policy. Commissioning policies set the criteria for service delivery and therefore have a major impact on the care received by patients. It is important that stakeholders have a good appreciation of the available evidence informing policy, as this will promote engagement both with the policy and with future research leading on from the policy. In this article, we provide stakeholders with a transparent and pragmatic assessment of the quality of the body of evidence available to inform current BCHD national policy. (i) A systematic review of the literature on BCHDs published since the development of the 2013 policy was performed in September 2016, adhering to PRISMA recommendations. The search terms used were as follows bone conduction; bone conducting; bone anchor; BAHA; Bone Anchored Hearing Aid; Bone Conducting Hearing Device; BCHD; Bone Conducting Hearing Implant; BCHI; Sophono; Bonebridge; Soundbite; Ponto; Hearing aid; implant; device; hearing device. Publications that could inform current BCHD policy were included. The quality of included articles was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. (ii) The quality of evidence referenced by the 2013 BAHA policy was assessed using the GRADE system. (i) Of the 2576 publications on BCHDs identified by the systematic search, 39 met the inclusion criteria for further analysis. Using the GRADE criteria, the quality of evidence was classified as of 'very low quality'. (ii) The 2013 BAHA policy was informed by 14 references. The GRADE system classifies the quality of evidence that informed the policy as of 'very low quality'. The GRADE system defines the body of evidence available to inform current national BCHD policy

  5. Stable electroluminescence from passivated nano-crystalline porous silicon using undecylenic acid

    Science.gov (United States)

    Gelloz, B.; Sano, H.; Boukherroub, R.; Wayner, D. D. M.; Lockwood, D. J.; Koshida, N.

    2005-06-01

    Stabilization of electroluminescence from nanocrystalline porous silicon diodes has been achieved by replacing silicon-hydrogen bonds terminating the surface of nanocrystalline silicon with more stable silicon-carbon (Si-C) bonds. Hydrosilylation of the surface of partially and anodically oxidized porous silicon samples was thermally induced at about 90 °C using various different organic molecules. Devices whose surface have been modified with stable covalent bonds shows no degradation in the EL efficiency and EL output intensity under DC operation for several hours. The enhanced stability can be attributed to the high chemical resistance of Si-C bonds against current-induced surface oxidation associated with the generation of nonradiative defects. Although devices treated with 1-decene exhibit reduced EL efficiency and brightness compared to untreatred devices, other molecules, such as ethyl-undecylenate and particularly undecylenic acid provide stable and more efficient visible electroluminescence at room temperature. Undecylenic acid provides EL brightness as high as that of an untreated device.

  6. Stable electroluminescence from passivated nano-crystalline porous silicon using undecylenic acid

    Energy Technology Data Exchange (ETDEWEB)

    Gelloz, B.; Sano, H.; Koshida, N. [Dept. Elec. and Elec. Eng., Tokyo Univ. of A and T, Koganei, Tokyo 184-8588 (Japan); Boukherroub, R. [Laboratoire de Physique de la Matiere Condensee, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau (France); Wayner, D.D.M.; Lockwood, D.J. [National Research Council, Ottawa (Canada)

    2005-06-01

    Stabilization of electroluminescence from nanocrystalline porous silicon diodes has been achieved by replacing silicon-hydrogen bonds terminating the surface of nanocrystalline silicon with more stable silicon-carbon (Si-C) bonds. Hydrosilylation of the surface of partially and anodically oxidized porous silicon samples was thermally induced at about 90 C using various different organic molecules. Devices whose surface have been modified with stable covalent bonds shows no degradation in the EL efficiency and EL output intensity under DC operation for several hours. The enhanced stability can be attributed to the high chemical resistance of Si-C bonds against current-induced surface oxidation associated with the generation of nonradiative defects. Although devices treated with 1-decene exhibit reduced EL efficiency and brightness compared to untreated devices, other molecules, such as ethyl-undecylenate and particularly undecylenic acid provide stable and more efficient visible electroluminescence at room temperature. Undecylenic acid provides EL brightness as high as that of an untreated device. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Evaluation of the Quality Control Program for Diagnostic Radiography and Fluoroscopy Devices in Syria during 2005-2013

    Directory of Open Access Journals (Sweden)

    M. H. Kharita

    2017-06-01

    Full Text Available Introduction: Extensive use of diagnostic radiology is the largest contributor to total population radiation doses. Thus, appropriate equipment and safe practice are necessary for good-quality images with optimal doses. This study aimed to perform quality control (QC audit for radiography and fluoroscopy devices owned by private sector in Syria (2005-2013 to verify compliance of performance of X-ray machines with the regulatory requirements stipulated by the national regulatory body. Materials and Methods: In this study, QC audit included 487 X-ray diagnostic machines, (363 radiography and 124 fluoroscopy devices, installed in 306 medical diagnostic radiology centers in 14 provinces in Syria. We employed an X-ray beam analyzer device (NERO model 8000, Victoreen, USA, which was tested and calibrated at the National Secondary Standard Dosimetry Laboratory traceable to the IAEA Network of Secondary Standard Dosimetry Laboratories. Standard QC tool kits were used to evaluate tube and generator of the X-ray machines, which constituted potential (kVp, timer accuracy, radiation output consistency, tube filtration, small and large focal spot sizes, X-ray beam collimation and alignment, as well as high- and low-resolution and entrance surface dose in fluoroscopy. Results: According to our results, most of the assessed operating parameters were in compliance with the standards stipulated by the National Regulatory Authority. In cases of noncompliance for the assessed parameters, maximum value (28.77% pertained to accuracy of kVp calibration for radiography units, while the lowest value (2.42% belonged to entrance surface dose in fluoroscopy systems. Conclusion: Effective QC program in diagnostic radiology leads to obtaining information regarding quality of radiology devices used for medical diagnosis and minimizing the doses received by patients and medical personnel. The findings of this QC program, as the main part of QA program, illustrated that most

  8. Photoelectrochemical Characterization of Nanocrystalline ZnS :Mn^(2+) Layers

    NARCIS (Netherlands)

    Suyver, J.F.; Bakker, R.; Meijerink, A.; Kelly, J.J.

    2000-01-01

    Measurements of the photoelectrochemical properties of nanocrystalline ZnS electrodes doped with Mn^(2+) are presented and discussed. The observation of both anodic and cathodic photocurrent is direct evidence for the nanocrystalline nature of the system. In-situ photoluminescence

  9. Nanocrystalline silicon prepared at high growth rate using helium ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Growth and optimization of the nanocrystalline silicon (nc-Si:H) films have been studied by varying the electrical power applied to the helium diluted silane plasma in RF glow discharge. Wide optical gap and conducting intrinsic nanocrystalline silicon network of controlled crystalline volume fraction and oriented.

  10. Solid state consolidation nanocrystalline copper-tungsten using cold spray

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Aaron Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sarobol, Pylin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Argibay, Nicolas [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Diantonio, Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    It is well known that nanostructured metals can exhibit significantly improved properties compared to metals with conventional grain size. Unfortunately, nanocrystalline metals typically are not thermodynamically stable and exhibit rapid grain growth at moderate temperatures. This severely limits their processing and use, making them impractical for most engineering applications. Recent work has shown that a number of thermodynamically stable nanocrystalline metal alloys exist. These alloys have been prepared as powders using severe plastic deformation (e.g. ball milling) processes. Consolidation of these powders without compromise of their nanocrystalline microstructure is a critical step to enabling their use as engineering materials. We demonstrate solid-state consolidation of ball milled copper-tantalum nanocrystalline metal powder using cold spray. Unfortunately, the nanocrystalline copper-tantalum powder that was consolidated did not contain the thermodynamically stable copper-tantalum nanostructure. Nevertheless, this does this demonstrates a pathway to preparation of bulk thermodynamically stable nanocrystalline copper-tantalum. Furthermore, it demonstrates a pathway to additive manufacturing (3D printing) of nanocrystalline copper-tantalum. Additive manufacturing of thermodynamically stable nanocrystalline metals is attractive because it enables maximum flexibility and efficiency in the use of these unique materials.

  11. Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

    International Nuclear Information System (INIS)

    Poffo, C.M.; Lima, J.C. de; Souza, S.M.; Triches, D.M.; Grandi, T.A.; Biasi, R.S. de

    2011-01-01

    Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 o C the heat transfer is controlled by crystalline component.

  12. Joint CDRH (Center for Devices and Radiological Health) and state quality-assurance surveys in nuclear medicine: Phase 2 - radiopharmaceuticals

    International Nuclear Information System (INIS)

    Hamilton, D.R.; Evans, C.D.

    1986-08-01

    The report discusses survey results on aspects of the quality assurance of radio-pharmaceuticals from 180 nuclear-medicine facilities in the United States. Data were collected from facilities in 8 states. Demographic information about nuclear-medicine operations and quality-assurance programs was gathered by state radiation-control-program personnel. The data collected from the survey show an incomplete acceptance of quality-assurance practices for radiopharmaceuticals. Most of the facilities in the survey indicated that, because an inferior radiopharmaceutical was prepared so infrequently, they did not believe it was cost-effective to perform extensive quality-assurance testing. The Center for Devices and Radiological Health hopes that the information from the survey will stimulate nuclear-medicine professionals and their organizations to encourage appropriate testing of all radiopharmaceuticals

  13. Innovative postmarket device evaluation using a quality registry to monitor thoracic endovascular aortic repair in the treatment of aortic dissection.

    Science.gov (United States)

    Beck, Adam W; Lombardi, Joseph V; Abel, Dorothy B; Morales, J Pablo; Marinac-Dabic, Danica; Wang, Grace; Azizzadeh, Ali; Kern, John; Fillinger, Mark; White, Rodney; Cronenwett, Jack L; Cambria, Richard P

    2017-05-01

    United States Food and Drug Administration (FDA)-mandated postapproval studies have long been a mainstay of the continued evaluation of high-risk medical devices after initial marketing approval; however, these studies often present challenges related to patient/physician recruitment and retention. Retrospective single-center studies also do not fully represent the spectrum of real-world performance nor are they likely to have a sufficiently large enough sample size to detect important signals. In recent years, The FDA Center for Devices and Radiological Health has been promoting the development and use of patient registries to advance infrastructure and methodologies for medical device investigation. The FDA 2012 document, "Strengthening the National System for Medical Device Post-market Surveillance," highlighted registries as a core foundational infrastructure when linked to other complementary data sources, including embedded unique device identification. The Vascular Quality Initiative (VQI) thoracic endovascular aortic repair for type B aortic dissection project is an innovative method of using quality improvement registries to meet the needs of device evaluation after market approval. Here we report the organization and background of this project and highlight the innovation facilitated by collaboration of physicians, the FDA, and device manufacturers. This effort used an existing national network of VQI participants to capture patients undergoing thoracic endovascular aortic repair for acute type B aortic dissection within a registry that aligns with standard practice and existing quality efforts. The VQI captures detailed patient, device, and procedural data for consecutive eligible cases under the auspices of a Patient Safety Organization (PSO). Patients were divided into a 5-year follow-up group (200 acute; 200 chronic dissections) and a 1-year follow-up group (100 acute; 100 chronic). The 5-year cohort required additional imaging details, and the 1-year

  14. A noble technique a using force-sensing resistor for immobilization-device quality assurance: A feasibility study

    Science.gov (United States)

    Cho, Min-Seok; Kim, Tae-Ho; Kang, Seong-Hee; Kim, Dong-Su; Kim, Kyeong-Hyeon; Shin, Dong-Seok; Noh, Yu-Yun; Koo, Hyun-Jae; Cheon, Geum Seong; Suh, Tae Suk; Kim, Siyong

    2016-03-01

    Many studies have reported that a patient can move even when an immobilization device is used. Researchers have developed an immobilization-device quality-assurance (QA) system that evaluates the validity of immobilization devices. The QA system consists of force-sensing-resistor (FSR) sensor units, an electric circuit, a signal conditioning device, and a control personal computer (PC) with in-house software. The QA system is designed to measure the force between an immobilization device and a patient's skin by using the FSR sensor unit. This preliminary study aimed to evaluate the feasibility of using the QA system in radiation-exposure situations. When the FSR sensor unit was irradiated with a computed tomography (CT) beam and a treatment beam from a linear accelerator (LINAC), the stability of the output signal, the image artifact on the CT image, and changing the variation on the patient's dose were tested. The results of this study demonstrate that this system is promising in that it performed within the error range (signal variation on CT beam < 0.30 kPa, root-mean-square error (RMSE) of the two CT images according to presence or absence of the FSR sensor unit < 15 HU, signal variation on the treatment beam < 0.15 kPa, and dose difference between the presence and the absence of the FSR sensor unit < 0.02%). Based on the obtained results, we will volunteer tests to investigate the clinical feasibility of the QA system.

  15. Improving Quality Control of Asphalt Pavement with RAP Using a Portable Infrared Spectroscopy Device

    Science.gov (United States)

    2016-04-01

    This project has investigated the effectiveness of a Portable Infrared Spectrometer (PIRS) device in estimating percent of Reclaimed Asphalt Pavement (RAP) and its contribution into oxidative aging of a new asphalt mixture immediately after productio...

  16. A randomised control trial of prompt and feedback devices and their impact on quality of chest compressions--a simulation study.

    Science.gov (United States)

    Yeung, Joyce; Davies, Robin; Gao, Fang; Perkins, Gavin D

    2014-04-01

    This study aims to compare the effect of three CPR prompt and feedback devices on quality of chest compressions amongst healthcare providers. A single blinded, randomised controlled trial compared a pressure sensor/metronome device (CPREzy), an accelerometer device (Phillips Q-CPR) and simple metronome on the quality of chest compressions on a manikin by trained rescuers. The primary outcome was compression depth. Secondary outcomes were compression rate, proportion of chest compressions with inadequate depth, incomplete release and user satisfaction. The pressure sensor device improved compression depth (37.24-43.64 mm, p=0.02), the accelerometer device decreased chest compression depth (37.38-33.19 mm, p=0.04) whilst the metronome had no effect (39.88 mm vs. 40.64 mm, p=0.802). Compression rate fell with all devices (pressure sensor device 114.68-98.84 min(-1), p=0.001, accelerometer 112.04-102.92 min(-1), p=0.072 and metronome 108.24 min(-1) vs. 99.36 min(-1), p=0.009). The pressure sensor feedback device reduced the proportion of compressions with inadequate depth (0.52 vs. 0.24, p=0.013) whilst the accelerometer device and metronome did not have a statistically significant effect. Incomplete release of compressions was common, but unaffected by the CPR feedback devices. Users preferred the accelerometer and metronome devices over the pressure sensor device. A post hoc study showed that de-activating the voice prompt on the accelerometer device prevented the deterioration in compression quality seen in the main study. CPR feedback devices vary in their ability to improve performance. In this study the pressure sensor device improved compression depth, whilst the accelerometer device reduced it and metronome had no effect. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Quality and Calibration of X-Ray Devices Used in Radiology

    OpenAIRE

    SONĞUR, Levent

    2013-01-01

    Calibration is defined as the relationship between the results obtained from the reference systems and the measurement devices, or briefly as the process of determining the magnitude of deviation from the correct values. The errors in the results produced by the measurement systems, which has been calibrated correctly, must be within the specified limits. Medical diagnosis and therapies are conducted by taking into account the results obtained from medical devices. So, the accuracy of the res...

  18. A Randomized Control Trial of Cardiopulmonary Feedback Devices and Their Impact on Infant Chest Compression Quality: A Simulation Study.

    Science.gov (United States)

    Austin, Andrea L; Spalding, Carmen N; Landa, Katrina N; Myer, Brian R; Donald, Cure; Smith, Jason E; Platt, Gerald; King, Heather C

    2017-10-27

    In effort to improve chest compression quality among health care providers, numerous feedback devices have been developed. Few studies, however, have focused on the use of cardiopulmonary resuscitation feedback devices for infants and children. This study evaluated the quality of chest compressions with standard team-leader coaching, a metronome (MetroTimer by ONYX Apps), and visual feedback (SkillGuide Cardiopulmonary Feedback Device) during simulated infant cardiopulmonary resuscitation. Seventy voluntary health care providers who had recently completed Pediatric Advanced Life Support or Basic Life Support courses were randomized to perform simulated infant cardiopulmonary resuscitation into 1 of 3 groups: team-leader coaching alone (control), coaching plus metronome, or coaching plus SkillGuide for 2 minutes continuously. Rate, depth, and frequency of complete recoil during cardiopulmonary resuscitation were recorded by the Laerdal SimPad device for each participant. American Heart Association-approved compression techniques were randomized to either 2-finger or encircling thumbs. The metronome was associated with more ideal compression rate than visual feedback or coaching alone (104/min vs 112/min and 113/min; P = 0.003, 0.019). Visual feedback was associated with more ideal depth than auditory (41 mm vs 38.9; P = 0.03). There were no significant differences in complete recoil between groups. Secondary outcomes of compression technique revealed a difference of 1 mm. Subgroup analysis of male versus female showed no difference in mean number of compressions (221.76 vs 219.79; P = 0.72), mean compression depth (40.47 vs 39.25; P = 0.09), or rate of complete release (70.27% vs 64.96%; P = 0.54). In the adult literature, feedback devices often show an increase in quality of chest compressions. Although more studies are needed, this study did not demonstrate a clinically significant improvement in chest compressions with the addition of a metronome or visual

  19. Radiation-Induced Damage and Recovery of Ultra-Nanocrystalline Diamond: Toward Applications in Harsh Environments.

    Science.gov (United States)

    Martin, Aiden A; Filevich, Jorge; Straw, Marcus; Randolph, Steven; Botman, Aurélien; Aharonovich, Igor; Toth, Milos

    2017-11-15

    Ultra-nanocrystalline diamond (UNCD) is increasingly being used in the fabrication of devices and coatings due to its excellent tribological properties, corrosion resistance, and biocompatibility. Here, we study its response to irradiation with kiloelectronvolt electrons as a controlled model for extreme ionizing environments. Real time Raman spectroscopy reveals that the radiation-damage mechanism entails dehydrogenation of UNCD grain boundaries, and we show that the damage can be recovered by annealing at 883 K. Our results have significant practical implications for the implementation of UNCD in extreme environment applications, and indicate that the films can be used as radiation sensors.

  20. Wirelessly Powered High-Temperature Strain Measuring Probe Based on Piezoresistive Nanocrystalline Diamond Layers

    Directory of Open Access Journals (Sweden)

    Bouřa Adam

    2016-09-01

    Full Text Available A high-temperature piezo-resistive nano-crystalline diamond strain sensor and wireless powering are presented in this paper. High-temperature sensors and electronic devices are required in harsh environments where the use of conventional electronic circuits is impractical or impossible. Piezo-resistive sensors based on nano-crystalline diamond layers were successfully designed, fabricated and tested. The fabricated sensors are able to operate at temperatures of up to 250°C with a reasonable sensitivity. The basic principles and applicability of wireless powering using the near magnetic field are also presented. The system is intended mainly for circuits demanding energy consumption, such as resistive sensors or devices that consist of discrete components. The paper is focused on the practical aspect and implementation of the wireless powering. The presented equations enable to fit the frequency to the optimal range and to maximize the energy and voltage transfer with respect to the coils’ properties, expected load and given geometry. The developed system uses both high-temperature active devices based on CMOS-SOI technology and strain sensors which can be wirelessly powered from a distance of up to several centimetres with the power consumption reaching hundreds of milliwatts at 200°C. The theoretical calculations are based on the general circuit theory and were performed in the software package Maple. The results were simulated in the Spice software and verified on a real sample of the measuring probe.

  1. Tissue quality assessment using a novel direct elasticity assessment device (the E-finger: a cadaveric study of prostatectomy dissection.

    Directory of Open Access Journals (Sweden)

    Daniel W Good

    examine the use of elasticity assessment devices for tissue quality assessment with the aim of giving haptic feedback to surgeons performing complex surgery.

  2. LIGHT-WEIGHT NANOCRYSTALLINE HYDROGEN STORAGE MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    S. G. Sankar; B. Zande; R.T. Obermyer; S. Simizu

    2005-11-21

    During Phase I of this SBIR Program, Advanced Materials Corporation has addressed two key issues concerning hydrogen storage: 1. We have conducted preliminary studies on the effect of certain catalysts in modifying the hydrogen absorption characteristics of nanocrystalline magnesium. 2. We have also conducted proof-of-concept design and construction of a prototype instrument that would rapidly screen materials for hydrogen storage employing chemical combinatorial technique in combination with a Pressure-Composition Isotherm Measurement (PCI) instrument. 3. Preliminary results obtained in this study approach are described in this report.

  3. Best practices in early phase medical device development: Engineering, prototyping, and the beginnings of a quality management system.

    Science.gov (United States)

    Fearis, Kristy; Petrie, Aidan

    2017-03-01

    Kristy Fearis is the founder and president of KPConsulting. She has held various positions in the medical device and research industry. She has led programs for medical industry leaders Medtronic, Edward Lifesciences, and Kimberly-Clark Healthcare to develop and commercialize Class II and III devices. Although a true quality management systems specialist at heart, Kristy has a passion for effectively and efficiently applying quality systems principles to early stage development to maximize benefit while minimizing impact on resources and time to market. Kristy works with both precommercial and commercial companies to build and implement quality systems that are "right sized" and support both an effective business model and high product quality. Aidan Petrie is the cofounder and chief innovation officer of Ximedica. Aidan drives innovation in Ximedica's core markets of medical device development and consumer healthcare. With a focus on human-centered design, usability, technical innovation and industrial design, Aidan has helped bring hundreds of products to market. Ranging from simple drug compliance aids to wearable therapeutics, home monitoring products, and complex surgical systems, Aidan challenges his teams to rethink the role design plays in the success of each product. Covering topics around usability, sensor and wearable technology, and current trends in medical design and development, Aidan is a sought-after industry speaker and widely published author. In addition to his role at Ximedica, Aidan advises multiple startups in the healthcare space and has interests in a number of related companies. He sits on the Board of MassArt and teaches and lectures at the Rhode Island School of Design, Massachusetts Institute of Technology, the Harvard iLab, and others. Aidan holds an undergraduate degree from Central St Martins in product design/engineering and a Masters in industrial design from the Rhode Island School of Design. Copyright © 2016 Elsevier Inc. All

  4. Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT devices

    Directory of Open Access Journals (Sweden)

    Ninita Lindfors

    Full Text Available Objectives: The aim of this in vitro study was to evaluate how a deviation from the horizontal plane, affects the image quality in two different CBCT-devices. Methods: A phantom head SK150 (RANDO, The Phantom Laboratory, Salem, NY, USA was examined in two CBCT-units: Accuitomo 80 and Veraviewepocs 3D R100 (J. Morita Mfg. Corp. Kyoto, Japan. The phantom head was placed with the hard palate parallel to the horizontal plane and tilted 20 ° backwards. Exposures were performed with different field of views (FOVs, voxel sizes, slice thicknesses and exposure settings. Effective dose was calculated using PCXMC 2.0 (STUK, Helsinki, Finland. Image quality was assessed using contrast-to-noise-ratio (CNR. Region of interest (ROI was set at three different levels of the mandibular bone and soft tissue, uni- and bilaterally in small and large FOVs, respectively. CNR values were calculated by CT-value and standard deviation for each ROI. Factor analysis was used to analyze the material. Results: Tilting the phantom head backwards rendered significantly higher mean CNR values regardless of FOV. The effective dose was lower in small than in large FOVs and varied to a larger extent between CBCT-devices in large FOVs. Conclusions: Head position can affect the image quality. Tilting the head backward improved image quality in the mandibular region. However, if influenced by other variables e.g. motion artifacts in a clinical situation, remains to be further investigated. Advances in knowledge: Image quality assessed using CNR values to investigate the influence of different patient positions and FOVs. Keywords: Image quality, CBCT, Radiation dose, Patient position, FOV

  5. Compact devices for generation of reference trace VOC mixtures: a new concept in assuring quality at chemical and biochemical laboratories.

    Science.gov (United States)

    Demichelis, Alessia; Pascale, Céline; Lecuna, Maricarmen; Niederhauser, Bernhard; Sassi, Guido; Sassi, Maria Paola

    2018-04-01

    Volatile organic compounds (VOCs) in gas mixtures at trace level (nmol/mol) are routinely measured by chemical and biochemical laboratories as climate indicators, indoor air quality pollutants from building materials emissions, contaminants in food and beverages, and biomarkers in body fluids (blood, urine, breath) of occupational exposure or human diseases. Current analytical instruments used for measurements are gas chromatographs equipped with various injector and detector configurations. The assurance of measurement quality is done by using a huge amount of certified liquid VOC standard solutions (or gaseous VOC standard cylinders) with multiple dilutions to reach the required trace level. This causes high standard uncertainty in instrument calibrations, high cost, and high consumption of analysis and laboratory personal time. In this paper, we present the implementation of portable generators producing VOC gas standards at trace level for automatic and direct calibration of VOC detectors employed in various contexts, removing the need for preparation of matrix calibration standards in cylinders. Two compact devices in-house developed by two national metrology institutes-the Istituto Nazionale di Ricerca Metrologica (INRIM) and the Federal Institute of Metrology (METAS)-are here used to dynamically generate reference gas mixtures in an SI traceable way. The two devices are based on different technologies: diffusion and permeation, for INRIM and METAS, respectively. A metrological characterization is given and the practical implementation at chemical and biochemical laboratories is discussed. Graphical abstract Onsite calibration with transportable generation system with similar performances to primary laboratory devices.

  6. Hydrazine-based deposition route for device-quality CIGS films

    International Nuclear Information System (INIS)

    Mitzi, David B.; Yuan, Min; Liu, Wei; Kellock, Andrew J.; Chey, S. Jay; Gignac, Lynne; Schrott, Alex G.

    2009-01-01

    A simple solution-based approach for depositing CIGS (Cu-In-Ga-Se/S) absorber layers is discussed, with an emphasis on film characterization, interfacial properties and integration into photovoltaic devices. The process involves incorporating all metal and chalcogenide components into a single hydrazine-based solution, spin coating a precursor film, and heat treating in an inert atmosphere, to form the desired CIGS film with up to micron-scaled film thickness and grain size. PV devices (glass/Mo/CIGS/CdS/i-ZnO/ITO) employing the spin-coated CIGS and using processing temperatures below 500 deg. C have yielded power conversion efficiencies of up to 10% (AM 1.5 illumination), without the need for a post-CIGS-deposition treatment in a gaseous Se source or a cyanide-based bath etch. Short-duration low-temperature (T < 200 deg. C ) oxygen treatment of completed devices is shown to have a positive impact on the performance of initially underperforming cells, thereby enabling better performance in devices prepared at temperatures below 500 deg. C

  7. Guide-09-1998. Quality control of darkrooms and image display devices

    International Nuclear Information System (INIS)

    2015-01-01

    This guide is applicable to process darkrooms relieved and receiving devices and image displays. A number of methods which require the appointed instrumentation described, some of which can be implemented in own radiology services in the country given the low complexity of themselves and others that require specific equipment and can be performed by specialized groups external to these units.

  8. Improving quality of experience by adding device resource reservation to service discovery protocols

    NARCIS (Netherlands)

    Delphinanto, A.; Koonen, A.M.J.; Hartog, F.T.H. den

    2008-01-01

    Current service discovery protocols (SDP) hardly provide information on the actual availability of resources in the network or a mechanism for (device) resource reservation. When the resources cannot serve all multiple client requests at the same time, conflicts happen, often involving heavy and

  9. Quality assurance device for four-dimensional IMRT or SBRT and respiratory gating using patient-specific intrafraction motion kernels.

    Science.gov (United States)

    Nelms, Benjamin E; Ehler, Eric; Bragg, Henry; Tomé, Wolfgang A

    2007-09-17

    Emerging technologies such as four-dimensional computed tomography (4D CT) and implanted beacons are expected to allow clinicians to accurately model intrafraction motion and to quantitatively estimate internal target volumes (ITVs) for radiation therapy involving moving targets. In the case of intensity-modulated (IMRT) and stereotactic body radiation therapy (SBRT) delivery, clinicians must consider the interplay between the temporal nature of the modulation and the target motion within the ITV. A need exists for a 4D IMRT/SBRT quality assurance (QA) device that can incorporate and analyze customized intrafraction motion as it relates to dose delivery and respiratory gating. We built a 4D IMRT/SBRT prototype device and entered (X, Y, Z)(T) coordinates representing a motion kernel into a software application that 1. transformed the kernel into beam-specific two-dimensional (2D) motion "projections," 2. previewed the motion in real time, and 3. drove a recision X-Y motorized device that had, atop it, a mounted planar IMRT QA measurement device. The detectors that intersected the target in the beam's-eye-view of any single phase of the breathing cycle (a small subset of all the detectors) were defined as "target detectors" to be analyzed for dose uniformity between multiple fractions. Data regarding the use of this device to quantify dose variation fraction-to-fraction resulting from target motion (for several delivery modalities and with and without gating) have been recently published. A combined software and hardware solution for patient-customized 4D IMRT/SBRT QA is an effective tool for assessing IMRT delivery under conditions of intrafraction motion. The 4D IMRT QA device accurately reproduced the projected motion kernels for all beam's-eye-view motion kernels. This device has been proved to, effectively quantify the degradation in dose uniformity resulting from a moving target within a static planning target volume, and, integrate with a commercial

  10. Quality assurance device for four‐dimensional IMRT or SBRT and respiratory gating using patient‐specific intrafraction motion kernels

    Science.gov (United States)

    Ehler, Eric; Bragg, Henry; Tomé, Wolfgang A.

    2007-01-01

    Emerging technologies such as four‐dimensional computed tomography (4D CT) and implanted beacons are expected to allow clinicians to accurately model intrafraction motion and to quantitatively estimate internal target volumes (ITVs) for radiation therapy involving moving targets. In the case of intensity‐modulated (IMRT) and stereotactic body radiation therapy (SBRT) delivery, clinicians must consider the interplay between the temporal nature of the modulation and the target motion within the ITV. A need exists for a 4D IMRT/SBRT quality assurance (QA) device that can incorporate and analyze customized intrafraction motion as it relates to dose delivery and respiratory gating. We built a 4D IMRT/SBRT prototype device and entered (X, Y, Z)(T) coordinates representing a motion kernel into a software application that transformed the kernel into beam‐specific two‐dimensional (2D) motion “projections,”previewed the motion in real time, anddrove a precision X–Y motorized device that had, atop it, a mounted planar IMRT QA measurement device. The detectors that intersected the target in the beam's‐eye‐view of any single phase of the breathing cycle (a small subset of all the detectors) were defined as “target detectors” to be analyzed for dose uniformity between multiple fractions. Data regarding the use of this device to quantify dose variation fraction‐to‐fraction resulting from target motion (for several delivery modalities and with and without gating) have been recently published. A combined software and hardware solution for patient‐customized 4D IMRT/ SBRT QA is an effective tool for assessing IMRT delivery under conditions of intrafraction motion. The 4D IMRT QA device accurately reproduced the projected motion kernels for all beam's‐eye‐view motion kernels. This device has been proved to • effectively quantify the degradation in dose uniformity resulting from a moving target within a static planning target volume, and • integrate

  11. Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

    Science.gov (United States)

    Shang, Jie; Xue, Wuhong; Ji, Zhenghui; Liu, Gang; Niu, Xuhong; Yi, Xiaohui; Pan, Liang; Zhan, Qingfeng; Xu, Xiao-Hong; Li, Run-Wei

    2017-06-01

    Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfO x /ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

  12. Random and uniform anisotropy in soft magnetic nanocrystalline alloys (invited)

    International Nuclear Information System (INIS)

    Flohrer, Sybille; Herzer, Giselher

    2010-01-01

    In amorphous and nanocrystalline transition metal based alloys with low magnetostriction, the soft magnetic properties are mainly determined by magneto-elastic and annealing-induced anisotropies which are uniform on a scale much larger than the exchange correlation length. Though, in the nanocrystalline case, there are situations where the random magneto-crystalline anisotropy of the grains becomes relevant. The present paper surveys the interplay between the random magneto-crystalline and the uniform field-induced anisotropy in nanocrystalline FeCuNbSiB soft magnets. Typical examples where the contribution of the random anisotropy becomes particularly visible in the magnetic domain structure will be reviewed.

  13. Nanocrystalline magnetic materials obtained by flash annealing

    Directory of Open Access Journals (Sweden)

    Murakami R.K.

    1999-01-01

    Full Text Available The aim of the present work was to produce enhanced-remanence nanocrystalline magnetic material by crystallizing amorphous or partially amorphous Pr4.5Fe77B18.5 alloys by the flash annealing process, also known as the dc-Joule heating process, and to determine the optimal conditions for obtaining good magnetic coupling between the magnetic phases present in this material. Ribbons of Pr4.5Fe77B18.5 were produced by melt spinning and then annealed for 10-30 s at temperatures 500 - 640 °C by passing current through the sample to develop the enhanced-remanence nanocrystalline magnetic material. These materials were studied by X-ray diffraction, differential thermal analysis and magnetic measurements. Coercivity increases of up to 15% were systematically observed in relation to furnace-annealed material. Two different samples were carefully examined: (i a sample annealed at 600 °C which showed the highest coercive field Hc and remanence ratio Mr/Ms and (ii a sample annealed at 520 °C which showed phase separation in the second quadrant demagnetization curve. Our results are in agreement with other studies which show that flash annealing improves the magnetic properties of some amorphous ferromagnetic ribbons.

  14. 137Cs radioactive check device for quality and stability control of dosimeters used in radiotherapy

    International Nuclear Information System (INIS)

    Alves, C.F.E.; Mondaini, C.V.; Leite, S.P.; Pires, E.J.; Magalhaes, L.A.G.; Daivd, M.G.; Almeida, C.E. de

    2015-01-01

    This paper describes the design and construction of a shielded container to store a used brachytherapy 137 Cs source. This system proposes a new option to check the periodical consistency and proper functioning of ionization chambers and electrometers used in radiotherapy. Since there is no similar equipment being produced in the Brazilian market and the chambers stability control is part of a licensing requirement this device was built to meet the needs of several radiotherapy centers without access to it. (author)

  15. The FDA and worldwide quality system requirements guidebook for medical devices

    National Research Council Canada - National Science Library

    Daniel, Amiram; Kimmelman, Ed; Trautman, Kimberly A

    2008-01-01

    "This new and expanded second edition maintains the organizational approach of the first and includes the requirements and guidance contained in the Quality System Regulation (QSReg), the ISO 13485...

  16. Application of Taguchi methodology to improve the functional quality of a mechanical device

    International Nuclear Information System (INIS)

    Regeai, Awatef Omar

    2005-01-01

    Manufacturing and quality control are recognized branches of engineering management. special attention has been made to improve thr tools and methods for the purpose of improving the products quality and finding solutions for any Obstacles and/or problems during the production process. Taguchi methodology is one of the most powerful techniques for improving product and manufacturing process quality at low cost. It is a strategical and practical method that aims to assist managers and industrial engineers to tackle manufacturing quality problems in a systematic and structured manner. The potential benefit of Taguchi methodology lies in its ease of use, its emphasis on reducing variability to give more economical products and hence the accessibility to the engineering fraternity for solving real life quality problems. This study applies Taguchi methodology to improve the functional quality of a local made chain gear by a purposed heat treatment process. The hardness of steel is generally a function not of its composition only, but rather of its heat treatment. The study investigates the effects of various heat treatment parameters, including ramp rate of heating, normalizing holding time, normalizing temperature, annealing holding time, annealing temperature, hardening holding time, hardening temperature, quenching media, tempering temperature and tempering holding time upon the hardness, which is a measure of resistance to plastic deformation. Both the analysis of means (ANOM) and Signal to Noise ratio (S/N) have been carried out for determining the optimal condition of the process. A significant improvement of the functional quality characteristic (hardness) by more than 32% was obtained. The Scanning Electron Microscopy technique was used in this study to obtain visual evidence of the quality and continuous improvement of the heat treated samples. (author)

  17. Parking lot runoff quality and treatment efficiencies of a hydrodynamic-settling device in Madison, Wisconsin, 2005-6

    Science.gov (United States)

    Horwatich, Judy A.; Bannerman, Roger T.

    2012-01-01

    A hydrodynamic-settling device was installed in 2004 to treat stormwater runoff from a roof and parking lot located at the Water Utility Administration Building in Madison, Wis. The U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, the City of Madison, cities in the Waukesha Permit Group, Hydro International, Earth Tech, Inc., National Sanitation Foundation International, and the U.S. Environmental Protection Agency, monitored the device from November 2005 through September 2006 to evaluate it as part of the U.S. Environmental Protection Agency's Environmental Technology Verification Program. Twenty-three runoff events monitored for flow volume and water quality at the device's inlet and outlet were used to calculate the percentage of pollutant reduction for the device. The geometric mean concentrations of suspended sediment (SS), "adjusted" total suspended solids (TSS), total phosphorus (TP), dissolved phosphorus (DP), total recoverable zinc (TZn), and total recoverable copper (TCu) measured at the inlet were 107 mg/L (milligrams per liter), 92 mg/L, 0.17 mg/L, 0.05 mg/L, 38 μg/L (micrograms per liter), and 12 μg/L, respectively, and these concentrations are in the range of values observed in stormwater runoff from other parking lots in Wisconsin and Michigan. Efficiency of the settling device was calculated using the efficiency ratio and summation of loads (SOL) methods. Using the efficiency ratio method, the device reduced concentrations of SS, and DP, by 19, and 15, percent, respectively. Using the efficiency ratio method, the device increased "adjusted" TSS and TZn concentrations by 5 and 19, respectively. Bypass occurred for 3 of the 23 runoff events used in this assessment, and the bypass flow and water-quality concentrations were used to determine the efficiency of the bypass system. Concentrations of SS, "adjusted" TSS, and DP were reduced for the system by 18, 5, and 18, respectively; however, TZn increased by 5

  18. Inter-grain coupling effects on Coulomb oscillations in dual-gated nanocrystalline silicon point-contact transistors

    International Nuclear Information System (INIS)

    Khalafalla, M.A.H.; Durrani, Z.A.K.; Mizuta, H.; Ahmed, H.; Oda, S.

    2005-01-01

    Inter-grain electron-coupling effects are investigated at 4.2 K in dual-gated, point-contact, single-electron transistors fabricated in nanocrystalline silicon. The nanocrystalline silicon film is ∼40 nm thick, with grains ∼10-30 nm in size. The point-contact transistor channel is ∼30 nmx30 nmx40 nm in size, with two side-gates. Only a few grains exist within the channel and different grains contribute in varying degrees to the device conduction. By modifying the inter-grain coupling using selective oxidation of the grain boundaries, both electrostatic and wavefunction-coupling effects can be observed in the Coulomb oscillations vs. the two gate voltages

  19. Room temperature hydrogen gas sensitivity of nanocrystalline pure tin oxide.

    Science.gov (United States)

    Shukla, S; Seal, S

    2004-01-01

    Nanocrystalline (6-8 nm) tin oxide (SnO2) thin film (100-150 nm) sensor is synthesized via sol-gel dip-coating process. The thin film is characterized using focused ion-beam microscopy (FIB) and high-resolution transmission electron microscopy (HRTEM) techniques to determine the film thickness and the nanocrystallite size. The utilization of nanocrystalline pure-SnO2 thin film to sense a typical reducing gas such as hydrogen, at room temperature, is demonstrated in this investigation. The grain growth behavior of nanocrystalline pure-SnO2 is analyzed, which shows very low activation energy (9 kJ/mol) for the grain growth within the nanocrystallite size range of 3-20 nm. This low activation energy value is correlated, via excess oxygen-ion vacancy concentration, with the room temperature hydrogen gas sensitivity of the nanocrystalline pure-SnO2 thin film sensor.

  20. Protein-modified nanocrystalline diamond thin films for biosensor applications.

    Science.gov (United States)

    Härtl, Andreas; Schmich, Evelyn; Garrido, Jose A; Hernando, Jorge; Catharino, Silvia C R; Walter, Stefan; Feulner, Peter; Kromka, Alexander; Steinmüller, Doris; Stutzmann, Martin

    2004-10-01

    Diamond exhibits several special properties, for example good biocompatibility and a large electrochemical potential window, that make it particularly suitable for biofunctionalization and biosensing. Here we show that proteins can be attached covalently to nanocrystalline diamond thin films. Moreover, we show that, although the biomolecules are immobilized at the surface, they are still fully functional and active. Hydrogen-terminated nanocrystalline diamond films were modified by using a photochemical process to generate a surface layer of amino groups, to which proteins were covalently attached. We used green fluorescent protein to reveal the successful coupling directly. After functionalization of nanocrystalline diamond electrodes with the enzyme catalase, a direct electron transfer between the enzyme's redox centre and the diamond electrode was detected. Moreover, the modified electrode was found to be sensitive to hydrogen peroxide. Because of its dual role as a substrate for biofunctionalization and as an electrode, nanocrystalline diamond is a very promising candidate for future biosensor applications.

  1. Pulsed nanocrystalline plasma electrolytic boriding as a novel ...

    Indian Academy of Sciences (India)

    WINTEC

    ; pulsed plasma electrolytic boriding; corrosion; nanocrystalline. 1. Introduction. Titanium possesses low density, high strength-to-weight ratio, high stiffness and strength (Donachie 2000; Lutjer- ing and Albrecht 2004). Commercially pure ...

  2. Rose bengal-sensitized nanocrystalline ceria photoanode for dye ...

    Indian Academy of Sciences (India)

    Rose bengal-sensitized nanocrystalline ceria photoanode for dye-sensitized solar cell application ... injection and transportation, wide bandgap nanostructured metal oxide semiconductors with dye adsorption surface and higher electron mobility are essential properties for photoanode in dyesensitizedsolar cells (DSSCs).

  3. Tailoring and patterning the grain size of nanocrystalline alloys

    International Nuclear Information System (INIS)

    Detor, Andrew J.; Schuh, Christopher A.

    2007-01-01

    Nanocrystalline alloys that exhibit grain boundary segregation can access thermodynamically stable or metastable states with the average grain size dictated by the alloying addition. Here we consider nanocrystalline Ni-W alloys and demonstrate that the W content controls the grain size over a very broad range: ∼2-140 nm as compared with ∼2-20 nm in previous work on strongly segregating systems. This trend is attributed to a relatively weak tendency for W segregation to the grain boundaries. Based upon this observation, we introduce a new synthesis technique allowing for precise composition control during the electrodeposition of Ni-W alloys, which, in turn, leads to precise control of the nanocrystalline grain size. This technique offers new possibilities for understanding the structure-property relationships of nanocrystalline solids, such as the breakdown of Hall-Petch strength scaling, and also opens the door to a new class of customizable materials incorporating patterned nanostructures

  4. High Temperature Stable Nanocrystalline SiGe Thermoelectric Material

    Science.gov (United States)

    Yang, Sherwin (Inventor); Matejczyk, Daniel Edward (Inventor); Determan, William (Inventor)

    2013-01-01

    A method of forming a nanocomposite thermoelectric material having microstructural stability at temperatures greater than 1000 C. The method includes creating nanocrystalline powder by cryomilling. The method is particularly useful in forming SiGe alloy powder.

  5. Amorphous and nanocrystalline materials preparation, properties, and applications

    CERN Document Server

    Inoue, A

    2001-01-01

    Amorphous and nanocrystalline materials are a class of their own. Their properties are quite different to those of the corresponding crystalline materials. This book gives systematic insight into their physical properties, structure, behaviour, and design for special advanced applications.

  6. Impact of exercise with TheraBite device on trismus and health-related quality of life: A prospective study.

    Science.gov (United States)

    Montalvo, Charlotte; Finizia, Caterina; Pauli, Nina; Fagerberg-Mohlin, Bodil; Andréll, Paulin

    2017-01-01

    Trismus is a common symptom in patients with head and neck cancer that affects many aspects of daily life negatively. The aim of this study was to investigate the impact of structured exercise with the jaw-mobilizing device TheraBite on trismus, trismus-related symptomatology, and health-related quality of life (HRQL) in patients with head and neck cancer. Fifteen patients with trismus (maximum interincisal opening [MIO] ≤35 mm) after oncologic treatment for head and neck cancer, underwent a 10-week exercise program with the TheraBite device and were followed regularly. Time between oncologic treatment and start of TheraBite exercise ranged from 0.7 to 14.8 years (average 6.2 years). MIO, trismus-related symptoms, and HRQL was assessed before and after exercise and after 6 months. A significant improvement in MIO was observed post-exercise (3.5 mm, 15.3%, p = 0.0002) and after 6-month of follow-up (4.7 mm, 22.1%, p = 0.0029). A statistically significant correlation was found between increased MIO and fewer trismus-related symptoms. In conclusion, exercise with TheraBite improved MIO and trismus-related symptoms in patients with trismus secondary to head and neck cancer. Structured exercise with the jaw-mobilizing device seems to be beneficial for patients with trismus independent of time since oncologic treatment.

  7. Effect of TV content in subjective assessment of video quality on mobile devices

    Science.gov (United States)

    Jumisko, Satu H.; Ilvonen, Ville P.; Vaananen-Vainio-Mattila, Kaisa A.

    2005-03-01

    Selection of test materials in subjective assessment methodology recommendations is based mainly on technical parameters. Materials should test the ability of the codec to cope with spatial and temporal redundancy. However consumers watch TV for a reason -- one of the main criteria is the interesting content. In this study we examined whether the content recognition and subjects" personal interests have an effect on quality assessment. We also studied subjective assessment criteria for video quality. The study was done using small resolution and low bit rate video in mobile phones in a laboratory environment. Altogether 135 subjects, aged 18-65 years, participated in the tests. The test started with a subjective assessment of video quality using well-known TV content. Afterwards a survey was done to measure content recognition and level of interests in the content. The test session ended up with a qualitative interview about evaluation criteria. Our studies showed that there is a connection between interest in content and given quality score with TV content. Therefore we raise a concern on content selection and recommend measuring the evaluator"s interest in content in subjective assessment studies. The study on subjective evaluation criteria revealed that subjects pay attention on content and quality impairments especially in regions of interest.

  8. Security and Privacy Qualities of Medical Devices: An Analysis of FDA Postmarket Surveillance

    Science.gov (United States)

    Kramer, Daniel B.; Baker, Matthew; Ransford, Benjamin; Molina-Markham, Andres; Stewart, Quinn; Fu, Kevin; Reynolds, Matthew R.

    2012-01-01

    Background Medical devices increasingly depend on computing functions such as wireless communication and Internet connectivity for software-based control of therapies and network-based transmission of patients’ stored medical information. These computing capabilities introduce security and privacy risks, yet little is known about the prevalence of such risks within the clinical setting. Methods We used three comprehensive, publicly available databases maintained by the Food and Drug Administration (FDA) to evaluate recalls and adverse events related to security and privacy risks of medical devices. Results Review of weekly enforcement reports identified 1,845 recalls; 605 (32.8%) of these included computers, 35 (1.9%) stored patient data, and 31 (1.7%) were capable of wireless communication. Searches of databases specific to recalls and adverse events identified only one event with a specific connection to security or privacy. Software-related recalls were relatively common, and most (81.8%) mentioned the possibility of upgrades, though only half of these provided specific instructions for the update mechanism. Conclusions Our review of recalls and adverse events from federal government databases reveals sharp inconsistencies with databases at individual providers with respect to security and privacy risks. Recalls related to software may increase security risks because of unprotected update and correction mechanisms. To detect signals of security and privacy problems that adversely affect public health, federal postmarket surveillance strategies should rethink how to effectively and efficiently collect data on security and privacy problems in devices that increasingly depend on computing systems susceptible to malware. PMID:22829874

  9. Reversal of exchange bias in nanocrystalline antiferromagnetic-ferromagnetic bilayers

    International Nuclear Information System (INIS)

    Prados, C; Pina, E; Hernando, A; Montone, A

    2002-01-01

    The sign of the exchange bias in field cooled nanocrystalline antiferromagnetic-ferromagnetic bilayers (Co-O and Ni-O/permalloy) is reversed at temperatures approaching the antiferromagnetic (AFM) blocking temperature. A similar phenomenon is observed after magnetic training processes at similar temperatures. These effects can be explained assuming that the boundaries of nanocrystalline grains in AFM layers exhibit lower transition temperatures than grain cores

  10. Quality assurance and independent dosimetry for an intraoperative x-ray device

    International Nuclear Information System (INIS)

    Eaton, D. J.

    2012-01-01

    Purpose: Quality assurance is an essential component of accurate and safe radiotherapy delivery, and should include measurements which are independent of manufacturer-provided calibration. However, the physical and dosimetric properties of the INTRABEAM compact mobile 50 kV x-ray source are different from conventional kilovoltage therapy units and few reports describe methods for independent checks, frequencies, or tolerances for quality assurance tests. Methods: Based on the available evidence and local experience, methods are described for determination of the key dosimetric parameters: beam quality, output, isotropy, and depth doses. Internal system checks are also described, along with measurements of long-term stability. Results: A small volume parallel plate ionization chamber in a liquid water tank is the gold standard for measurements with this unit, but solid water-equivalent materials, thermoluminescent dosimeters and radiochromic film can all be used as practical alternatives with an accuracy of 5%–10%. The main cause of measurement uncertainty is positioning of the detector in the steep dose gradient, but energy dependence should also be considered. Conclusions: A quality assurance schedule with suggested tolerances is proposed, which includes both internal tests, before each treatment and on a monthly basis, and independent tests every year or after servicing or recalibration.

  11. Thermal Conductivity in Nanocrystalline Ceria Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Marat Khafizov; In-Wook Park; Aleksandr Chernatynskiy; Lingfeng He; Jianliang Lin; John J. Moore; David Swank; Thomas Lillo; Simon R. Phillpot; Anter El-Azab; David H. Hurley

    2014-02-01

    The thermal conductivity of nanocrystalline ceria films grown by unbalanced magnetron sputtering is determined as a function of temperature using laser-based modulated thermoreflectance. The films exhibit significantly reduced conductivity compared with stoichiometric bulk CeO2. A variety of microstructure imaging techniques including X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron analysis, and electron energy loss spectroscopy indicate that the thermal conductivity is influenced by grain boundaries, dislocations, and oxygen vacancies. The temperature dependence of the thermal conductivity is analyzed using an analytical solution of the Boltzmann transport equation. The conclusion of this study is that oxygen vacancies pose a smaller impediment to thermal transport when they segregate along grain boundaries.

  12. Reinforced plastics and aerogels by nanocrystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T., E-mail: john.luong@cnrc-nrc.gc.ca [National Research Council Canada (Canada)

    2013-05-15

    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  13. Nanocrystalline Steels’ Resistance to Hydrogen Embrittlement

    Directory of Open Access Journals (Sweden)

    Skołek E.

    2015-04-01

    Full Text Available The aim of this study is to determine the susceptibility to hydrogen embrittlement in X37CrMoV5-1 steel with two different microstructures: a nanocrystalline carbide-free bainite and tempered martensite. The nanobainitic structure was obtained by austempering at the bainitic transformation zone. It was found, that after hydrogen charging, both kinds of microstructure exhibit increased yield strength and strong decrease in ductility. It has been however shown that the resistance to hydrogen embrittlement of X37CrMoV5-1 steel with nanobainitic structure is higher as compared to the tempered martensite. After hydrogen charging the ductility of austempered steel is slightly higher than in case of quenched and tempered (Q&T steel. This effect was interpreted as a result of phase composition formed after different heat treatments.

  14. Device quality ZnO grown using a Filtered Cathodic Vacuum Arc

    International Nuclear Information System (INIS)

    Elzwawi, Salim; Kim, Hyung Suk; Heinhold, Robert; Lynam, Max; Turner, Gary; Partridge, Jim G.; McCulloch, Dougal G.

    2012-01-01

    In this paper we report on the structural, electrical and optical characteristics of unintentionally doped ZnO films grown on a-plane sapphire substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. The resulting films showed considerable promise for device applications with properties including high transparency, moderate intrinsic carrier concentrations (10 17 -10 19 cm -3 ), electron mobilities up to 30 cm 2 /Vs, low surface roughness (typically <2% of film thickness) and well-structured photoluminescence. Post-annealing in oxygen at temperatures up to 800 °C produced significant improvements in the properties of these films. Silver oxide Schottky diodes fabricated on FCVA ZnO showed ideality factors as low as 1.20 and good sensitivity to ultraviolet light.

  15. Real time chromametry measurement for food quality detection using mobile device

    Science.gov (United States)

    Witjaksono, Gunawan; Mohamad Hussin, Nur Haziqah Farah Binti; Abdelkreem Saeed Rabih, Almur; Alfa, Sagir

    2017-09-01

    Freshness of the food is the main factor in determining the quality and safety of the consumed food and hence consumers satisfaction. Current technologies for food quality determination depend on colour changing labels to indicate the freshness level, which is subjective to human eyes. The goal of this paper is to design and develop chromatic algorithm based on RGB colour reading and correlation with pH values for real time determination of freshness level of shrimp. The results show that the developed algorithm is able to measure, analyse and display the freshness level of food directly on the screen of a mobile app technology. The mobile app is developed on Android platform and is tested in the shrimp freshness range by stating whether it is “fresh, good or spoiled”.

  16. Quality control of a medicinal larval (Lucilia sericata) debridement device based on released gelatinase activity

    OpenAIRE

    Pickles, S.F.; Pritchard, David I.

    2017-01-01

    Lucilia sericata Meigen (Diptera: Calliphoridae) larvae are manufactured worldwide for the treatment of chronic wounds. Published research has confirmed that the primary clinical effect of the product, debridement (the degradation of non-viable wound tissue), is accomplished by a range of enzymes released by the larvae during feeding. The quality assessment of larval activity is currently achieved during production using meat-based assays, which monitor insect growth and/or the reduction in s...

  17. Design and Development of a Low-Cost, Portable Monitoring Device for Indoor Environment Quality

    Directory of Open Access Journals (Sweden)

    Akira Tiele

    2018-01-01

    Full Text Available This article describes the design and development of a low-cost, portable monitoring system for indoor environment quality (IEQ. IEQ is a holistic concept that encompasses elements of indoor air quality (IAQ, indoor lighting quality (ILQ, acoustic comfort, and thermal comfort (temperature and relative humidity. The unit is intended for the monitoring of temperature, humidity, PM2.5, PM10, total VOCs (×3, CO2, CO, illuminance, and sound levels. Experiments were conducted in various environments, including a typical indoor working environment and outdoor pollution, to evaluate the unit’s potential to monitor IEQ parameters. The developed system was successfully able to monitor parameter variations, based on specific events. A custom IEQ index was devised to rate the parameter readings with a simple scoring system to calculate an overall IEQ percentage. The advantages of the proposed system, with respect to commercial units, is associated with better customisation and flexibility to implement a variety of low-cost sensors. Moreover, low-cost sensor modules reduce the overall cost to provide a comprehensive, portable, and real-time monitoring solution. This development facilities researchers and interested enthusiasts to become engaged and proactive in participating in the study, management, and improvement of IEQ.

  18. Quality control of a medicinal larval (Lucilia sericata) debridement device based on released gelatinase activity.

    Science.gov (United States)

    Pickles, S F; Pritchard, D I

    2017-06-01

    Lucilia sericata Meigen (Diptera: Calliphoridae) larvae are manufactured worldwide for the treatment of chronic wounds. Published research has confirmed that the primary clinical effect of the product, debridement (the degradation of non-viable wound tissue), is accomplished by a range of enzymes released by larvae during feeding. The quality assessment of larval activity is currently achieved during production using meat-based assays, which monitor insect growth and/or the reduction in substrate mass. To support this, the present authors developed a complementary radial diffusion enzymatic assay to produce a visual and measureable indication of the activity of larval alimentary products (LAP) collected under standardized conditions, against a gelatin substrate. Using basic laboratory equipment and reagents, the assay is rapid and suited to high throughput. Assay reproducibility is high (standard deviation: 0.06-0.27; coefficient of variation: 0.75-4.31%) and the LAP collection procedure does not adversely affect larval survival (mortality: quality control assay. © 2017 The Royal Entomological Society.

  19. Development and Evaluation of a Wearable Device for Sleep Quality Assessment.

    Science.gov (United States)

    Kuo, Chih-En; Liu, Yi-Che; Chang, Da-Wei; Young, Chung-Ping; Shaw, Fu-Zen; Liang, Sheng-Fu

    2017-07-01

    In this study, a wearable actigraphy recording device with low sampling rate (1 Hz) for power saving and data reduction and a high accuracy wake-sleep scoring method for the assessment of sleep were developed. The developed actigraphy recorder was successfully applied to overnight recordings of 81 subjects with simultaneous polysomnography (PSG) measurements. The total length of recording reached 639.8 h. A wake-sleep scoring method based on the concept of movement density evaluation and adaptive windowing was proposed. Data from subjects with good (N = 43) and poor (N = 16) sleep efficiency (SE) in the range of 52.7-97.42% were used for testing. The Bland-Altman technique was used to evaluate the concordance of various sleep measurements between the manual PSG scoring and the proposed actigraphy method. For wake-sleep staging, the average accuracy, sensitivity, specificity, and kappa coefficient of the proposed system were 92.16%, 95.02%, 71.30%, and 0.64, respectively. For the assessment of SE, the accuracy of classifying the subject with good or poor SE reached 91.53%. The mean biases of SE, sleep onset time, wake after sleep onset, and total sleep time were -0.95%, 0.74 min, 2.84 min, and -4.3 min, respectively. These experimental results demonstrate the robustness and reliability of our method using limited activity information to estimate wake-sleep stages during overnight recordings. The results suggest that the proposed wearable actigraphy system is practical for the in-home screening of objective sleep measurements and objective evaluation of sleep improvement after treatment.

  20. SU-F-T-11: Scintillator Based Quality Assurance Device for HDR Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Jozsef, G [New York University Medical Center, New York, NY (United States)

    2016-06-15

    Purpose: To build a test device for HDR afterloaders capable of checking source positions, times at positions and estimate the activity of the source. Methods: A catheter is taped on a plastic scintillation sheet. When a source travels through the catheter, the scintillator sheet lights up around the source. The sheet is monitored with a video camera, and records the movement of the light spot. The center of the spot on each image on the video provides the source location, and the time stamps of the images can provide the dwell time the source spend in each location. Finally, the brightness of the light spot is related to the activity of the source. A code was developed for noise removal, calibrate the scale of the image to centimeters, eliminate the distortion caused by the oblique view angle, identifying the boundaries of the light spot, transforming the image into binary and detect and calculate the source motion, positions and times. The images are much less noisy if the camera is shielded. That requires that the light spot is monitored in a mirror, rather than directly. The whole assembly is covered from external light and has a size of approximately 17×35×25cm (H×L×W) Results: A cheap camera in BW mode proved to be sufficient with a plastic scintillator sheet. The best images were resulted by a 3mm thick sheet with ZnS:Ag surface coating. The shielding of the camera decreased the noise, but could not eliminate it. A test run even in noisy condition resulted in approximately 1 mm and 1 sec difference from the planned positions and dwell times. Activity tests are in progress. Conclusion: The proposed method is feasible. It might simplify the monthly QA process of HDR Brachytherapy units.

  1. Synthesis of nanocrystalline CdS thin films in PVA matrix

    Indian Academy of Sciences (India)

    TECS

    The band gap of the nanocrystalline material is determined from the UV spectrograph. The absorption edge is shifted towards the lower wave length side (i.e. blue ... In recent years nanocrystalline thin films of different II–VI compound semiconductors have been widely synthesized and studied. Nanocrystalline thin films are ...

  2. A portable nondestructive detection device of quality and nutritional parameters of meat using Vis/NIR spectroscopy

    Science.gov (United States)

    Wang, Wenxiu; Peng, Yankun; Wang, Fan; Sun, Hongwei

    2017-05-01

    The improvement of living standards has urged consumers to pay more attention to the quality and nutrition of meat, so the development of nondestructive detection device for quality and nutritional parameters is commercioganic undoubtedly. In this research, a portable device equipped with visible (Vis) and near-infrared (NIR) spectrometers, tungsten halogen lamp, optical fiber, ring light guide and embedded computer was developed to realize simultaneous and fast detection of color (L*, a*, b*), pH, total volatile basic nitrogen (TVB-N), intramuscular fat (IF), protein and water content in pork. The wavelengths of dual-band spectrometers were 400 1100 nm and 940 1650 nm respectively and the tungsten halogen lamp cooperated with ring light guide to form a ring light source and provide appropriate illumination intensity for sample. Software was self-developed to control the functionality of dual-band spectrometers, set spectrometer parameters, acquire and process Vis/NIR spectroscopy and display the prediction results in real time. In order to obtain a robust and accurate prediction model, fresh longissimus dorsi meat was bought and placed in the refrigerator for 12 days to get pork samples with different freshness degrees. Besides, pork meat from three different parts including longissimus dorsi, haunch and lean meat was collected for the determination of IF, protein and water to make the reference values have a wider distribution range. After acquisition of Vis/NIR spectra, data from 400 1100 nm were pretreated with Savitzky-Golay (S-G) filter and standard normal variables transform (SNVT) and spectrum data from 940 1650 nm were preprocessed with SNVT. The anomalous were eliminated by Monte Carlo method based on model cluster analysis and then partial least square regression (PLSR) models based on single band (400 1100 nm or 940 1650 nm) and dual-band were established and compared. The results showed the optimal models for each parameter were built with correlation

  3. Thermoluminescent properties of nanocrystalline ZnTe thin films: Structural and morphological studies

    Science.gov (United States)

    Rajpal, Shashikant; Kumar, S. R.

    2018-04-01

    Zinc Telluride (ZnTe) is a binary II-VI direct band gap semiconducting material with cubic structure and having potential applications in different opto-electronic devices. Here we investigated the effects of annealing on the thermoluminescence (TL) of ZnTe thin films. A nanocrystalline ZnTe thin film was successfully electrodeposited on nickel substrate and the effect of annealing on structural, morphological, and optical properties were studied. The TL emission spectrum of as deposited sample is weakly emissive in UV region at ∼328 nm. The variation in the annealing temperature results into sharp increase in emission intensity at ∼328 nm along with appearance of a new peak at ∼437 nm in visible region. Thus, the deposited nanocrystalline ZnTe thin films exhibited excellent thermoluminescent properties upon annealing. Furthermore, the influence of annealing (annealed at 400 °C) on the solid state of ZnTe were also studied by XRD, SEM, EDS, AFM. It is observed that ZnTe thin film annealed at 400 °C after deposition provide a smooth and flat texture suited for optoelectronic applications.

  4. The impact of technology dependency on device acceptance and quality of life in persons with implantable cardioverter defibrillators.

    Science.gov (United States)

    Udlis, Kimberly A

    2013-01-01

    The impact of implantable cardioverter defibrillator (ICD) technology on the quality of life (QOL) experienced by recipients has been a major focus of recent research. Numerous studies have found psychological distress to be important in determining QOL in persons receiving ICDs, yet the source of psychological distress is not well understood. The aim of this study was to determine the impact of technology dependency on psychological outcomes in ICD recipients. With the use of a cross-sectional design, 161 ICD recipients from 1 device clinic were mailed self-administered questionnaires, including the Dependency on Technology Scale, Brief Illness Perception Questionnaire, Florida Shock Anxiety Scale, Florida Patient Acceptance Survey, and Short Form-12 (SF-12). Hierarchical multiple regressions and analyses of variance were performed. The final sample size was 101 participants. Mean (SD) age was 68 (13) years; 72% of the participants were men, 99% were white, and 30% reported receiving a shock(s). A total of 80% reported positive attitudes toward technology dependency; 14%, neutral; and 6%, negative (Dependency on Technology Scale). Illness perceptions were positive (Brief Illness Perception Questionnaire; mean[SD], 34.5 [12.6]), shock anxiety was elevated (Florida Shock Anxiety Scale; mean [SD], 16.5 [6.7]), and device acceptance was good (Florida Patient Acceptance Survey; mean [SD], 74.9 [17.0]). Physical health QOL was low (SF-12; mean [SD], 38.6 [11.3]) and mental health QOL was moderate (SF-12; mean [SD], 50.6 [10.0]). Attitudes toward technology dependency significantly accounted for the variance seen in device acceptance and mental health QOL beyond age, gender, number of shocks, illness perceptions, and shock anxiety by 5.7% (P = .001) and 3.3% (P = .04), respectively. Significant differences were seen in device acceptance between those with negative and neutral attitudes (P = .001) and those with negative and positive attitudes (P technology dependency is

  5. Sector-Based Radio Resource Allocation (SBRRA) Algorithm for Better Quality of Service and Experience in Device-to-Device (D2D) Communication

    OpenAIRE

    Gandotra, Pimmy; Jha, Rakesh Kumar; Jain, Sanjeev

    2018-01-01

    The mounting content sharing among users has resulted in a considerable rise in wireless data traffic, pressurizing the cellular networks to undergo a suitable upheaval. A competent technology of the fifth-generation networks (5G) for efficiently supporting proximity-based applications is Device-to-Device (D2D) communication, underlaying cellular networks. Significant advances have been made till date, for allocating resources to D2D users in cellular networks, such that sharing of spectral r...

  6. A novel electronic nose as adaptable device to judge microbiological quality and safety in foodstuff.

    Science.gov (United States)

    Sberveglieri, V; Carmona, E Nunez; Comini, Elisabetta; Ponzoni, Andrea; Zappa, Dario; Pirrotta, Onofrio; Pulvirenti, A

    2014-01-01

    This paper presents different applications, in various foodstuffs, by a novel electronic nose (EN) based on a mixed metal oxide sensors array composed of thin films as well as nanowires. The electronic nose used for this work has been done, starting from the commercial model EOS835 produced by SACMI Scarl. The SENSOR Lab (CNR-INO, Brescia) has produced both typologies of sensors, classical MOX and the new technologies with nanowire. The aim of this work was to test and to illustrate the broad spectrum of potential uses of the EN technique in food quality control and microbial contamination diagnosis. The EN technique was coupled with classical microbiological and chemical techniques, like gas chromatography with mass spectroscopy (GC-MS) with SPME technique. Three different scenarios are presented: (a) detection of indigenous mould in green coffee beans, (b) selection of microbiological spoilage of Lactic Acid Bacteria (LAB), and (c) monitoring of potable water. In each case, the novel EN was able to identify the spoiled product by means of the alterations in the pattern of volatile organic compounds (VOCs), reconstructed by principal component analysis (PCA) of the sensor responses. The achieved results strongly encourage the use of EN in industrial laboratories. Finally, recent trends and future directions are illustrated.

  7. A Novel Electronic Nose as Adaptable Device to Judge Microbiological Quality and Safety in Foodstuff

    Directory of Open Access Journals (Sweden)

    V. Sberveglieri

    2014-01-01

    Full Text Available This paper presents different applications, in various foodstuffs, by a novel electronic nose (EN based on a mixed metal oxide sensors array composed of thin films as well as nanowires. The electronic nose used for this work has been done, starting from the commercial model EOS835 produced by SACMI Scarl. The SENSOR Lab (CNR-INO, Brescia has produced both typologies of sensors, classical MOX and the new technologies with nanowire. The aim of this work was to test and to illustrate the broad spectrum of potential uses of the EN technique in food quality control and microbial contamination diagnosis. The EN technique was coupled with classical microbiological and chemical techniques, like gas chromatography with mass spectroscopy (GC-MS with SPME technique. Three different scenarios are presented: (a detection of indigenous mould in green coffee beans, (b selection of microbiological spoilage of Lactic Acid Bacteria (LAB, and (c monitoring of potable water. In each case, the novel EN was able to identify the spoiled product by means of the alterations in the pattern of volatile organic compounds (VOCs, reconstructed by principal component analysis (PCA of the sensor responses. The achieved results strongly encourage the use of EN in industrial laboratories. Finally, recent trends and future directions are illustrated.

  8. A new dental powder from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons

    International Nuclear Information System (INIS)

    Do-Minh, N.; Le-Thi, C.; Nguyen-Anh, S.

    2003-01-01

    A new non-gamma-two dental powder has been developed from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons. The amalgam made from this powder exhibits excellent properties for dental filling. The nanocrystalline microstructure was found for the first time in as-spun and heat treated Ag(27-28)Sn(9-32) Cu alloy ribbons, using X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. As-spun ribbons exhibited a multi-phase microstructure with preferred existence of β (Ag 4 Sn) phase formed during rapid solidification (RS) due to supersaturating of copper (Cu) atoms and homogenous nanostructure with subgrain size of about (40-50) nm, which seems to be developed during RS process and can be caused by eutectic reaction of the Ag 3 Sn/Ag 4 Sn-Cu 3 Sn system. In heat treated ribbons the clustering of Cu atoms was always favored and stable in an ageing temperature and time interval determined by Cu content. The heat treatment led to essential changes of subgrain morphology, resulted in the appearance of large-angle boundaries with fine Cu 3 Sn precipitates and forming typical recrystallization twins. Such a microstructure variation in melt-spun ribbons could eventually yield enhanced technological, clinical and physical properties of the dental products, controlled by the ADA Specification N deg 1 and reported before. Thus, using the rapid solidification technique a new non-gamma-two dental material of high quality, nanocrystalline ribbon powder, can be produced. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  9. Characterisation of Suspension Precipitated Nanocrystalline Hydroxyapatite Powders

    Science.gov (United States)

    Mallik, P. K.; Swain, P. K.; Patnaik, S. C.

    2016-02-01

    Hydroxyapatite (HA) is a well-known biomaterial for coating on femoral implants, filling of dental cavity and scaffold for tissue replacement. Hydroxyapatite possess limited load bearing capacity due to their brittleness. In this paper, the synthesis of nanocrystalline hydroxyapatite powders was prepared by dissolving calcium oxide in phosphoric acid, followed by addition of ammonia liquor in a beaker. The prepared solution was stirred by using magnetic stirrer operated at temperature of 80°C for an hour. This leads to the formation of hydroxyapatite precipitate. The precipitate was dried in oven for overnight at 100°C. The dried agglomerated precipitate was calcined at 800°C in conventional furnace for an hour. The influence of calcium oxide concentration and pH on the resulting precipitates was studied using BET, XRD and SEM. As result, a well-defined sub-rounded morphology of powders size of ∼41 nm was obtained with a salt concentration of 0.02 M. Finally, it can be concluded that small changes in the reaction conditions led to large changes in final size, shape and degree of aggregation of the hydroxyapatite particles.

  10. Equation of state of nanocrystalline forsterite

    Science.gov (United States)

    Couvy, H.; Chen, J.; Drozd, V.

    2008-12-01

    Grain size and grain shape are important parameters for physical properties of minerals as well as for geophysical processes like deformation. Even though the occurrences of nanominerals in the crust and the mantle are limited their presence might have an important influence. For instance, mechanical grinding of rocks associated to earthquake can generate nanoparticles and their presence is thought to control earthquake instability. In the context of subducting slab, experiments show presence of nanoparticle of ringwoodite which plays a important role in deep earthquakes. However, the influence of nano grain size on elastic properties of minerals is poorly studied. This work presents a study of equation of state of nano-forsterite. Nanocrystalline forsterite has been synthesized using a sol-gel method. A particle size of about 50 nm has been obtained. In-situ hydrostatic high pressure and high temperature experiments have been performed at X17B2 (NSLS) using the DIA-type multianvil press. Two samples of macron size and nano size particles of forsterite have been studied simultaneously up to 10 GPa and 1300°C for comparison. The bulk modulus of both samples and its derivative with pressure and temperature will presented and the consequences for geological processes will be discussed.

  11. Thermally Stimulated Currents in Nanocrystalline Titania

    Directory of Open Access Journals (Sweden)

    Mara Bruzzi

    2018-01-01

    Full Text Available A thorough study on the distribution of defect-related active energy levels has been performed on nanocrystalline TiO2. Films have been deposited on thick-alumina printed circuit boards equipped with electrical contacts, heater and temperature sensors, to carry out a detailed thermally stimulated currents analysis on a wide temperature range (5–630 K, in view to evidence contributions from shallow to deep energy levels within the gap. Data have been processed by numerically modelling electrical transport. The model considers both free and hopping contribution to conduction, a density of states characterized by an exponential tail of localized states below the conduction band and the convolution of standard Thermally Stimulated Currents (TSC emissions with gaussian distributions to take into account the variability in energy due to local perturbations in the highly disordered network. Results show that in the low temperature range, up to 200 K, hopping within the exponential band tail represents the main contribution to electrical conduction. Above room temperature, electrical conduction is dominated by free carriers contribution and by emissions from deep energy levels, with a defect density ranging within 1014–1018 cm−3, associated with physio- and chemi-sorbed water vapour, OH groups and to oxygen vacancies.

  12. Rheological properties of nanocrystalline cellulose suspensions.

    Science.gov (United States)

    Chen, Yang; Xu, Chunjiang; Huang, Jing; Wu, Defeng; Lv, Qiaolian

    2017-02-10

    Rheological behavior, including linear and nonlinear, as well as transient rheology of nanocrystalline cellulose (NCC) suspensions was studied in this work. Two kinds of polymer solutions, aqueous poly(vinyl alcohol) (PVA) with flexible chain structure and aqueous carboxymethyl cellulose (CMC) with semi-rigid chain structure, were used as the suspension media to further explore the role that the interactions among NCC and polymers played during shear flow. The results reveal that NCC has lower values of percolation threshold in the PVA solution than in the CMC one during small amplitude oscillatory shear (SAOS) flow because the flexible PVA chain has higher adsorbed level onto NCC particles than the negatively charged semi-rigid CMC chain, which is further confirmed by the Fourier transformed infrared (FT-IR) spectroscopy tests. As a result, the NCC suspension shows a weak strain overshoot in PVA solution during large amplitude oscillatory shear (LAOS) flow, which cannot be seen on the one in CMC solution. During startup shear flow, both of these two suspensions show evident stress overshoot behavior with the strain-scaling characteristics, indicating the formation of ordered long-term structure of rod-like NCC particles with self-similarity during flow. However, NCC suspension have far stronger stress overshoot response in CMC solution relative to the one in PVA solution. A possible synergy mechanism between NCC and CMC chain is hence proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Films prepared from electrosterically stabilized nanocrystalline cellulose.

    Science.gov (United States)

    Yang, Han; Tejado, Alvaro; Alam, Nur; Antal, Miro; van de Ven, Theo G M

    2012-05-22

    Electrosterically stabilized nanocrystalline cellulose (ENCC) was modified in three ways: (1) the hydroxyl groups on C2 and C3 of glucose repeat units of ENCC were converted to aldehyde groups by periodate oxidation to various extents; (2) the carboxyl groups in the sodium form on ENCC were converted to the acid form by treating them with an acid-type ion-exchange resin; and (3) ENCC was cross-linked in two different ways by employing adipic dihydrazide as a cross-linker and water-soluble 1-ethyl-3-[3-(dimethylaminopropyl)] carbodiimide as a carboxyl-activating agent. Films were prepared from these modified ENCC suspensions by vacuum filtration. The effects of these three modifications on the properties of films were investigated by a variety of techniques, including UV-visible spectroscopy, a tensile test, thermogravimetric analysis (TGA), the water vapor transmission rate (WVTR), and contact angle (CA) studies. On the basis of the results from UV spectra, the transmittance of these films was as high as 87%, which shows them to be highly transparent. The tensile strength of these films was increased with increasing aldehyde content. From TGA and WVTR experiments, cross-linked films showed much higher thermal stability and lower water permeability. Furthermore, although the original cellulose is hydrophilic, these films also exhibited a certain hydrophobic behavior. Films treated by trichloromethylsilane become superhydrophobic. The unique characteristics of these transparent films are very promising for potential applications in flexible packaging and other high-technology products.

  14. Synthesis of Nanocrystalline Cellulose Stabilized Copper Nanoparticles

    Directory of Open Access Journals (Sweden)

    Aminu Musa

    2016-01-01

    Full Text Available A chemical reduction method was employed for the synthesis of copper nanoparticles stabilized by nanocrystalline cellulose (NCC using different concentrations of copper salt in aqueous solution under atmospheric air. CuSO4·5H2O salt and hydrazine were used as metal ion precursor and reducing agent, respectively. Ascorbic acid and aqueous NaOH were also used as an antioxidant and a pH moderator, respectively. The number of CuNPs increased with increasing concentration of the precursor salt. The formation of copper nanoparticles stabilized by NCC (CuNPs@NCC was investigated by UV-visible spectroscopy (UV-vis, where the surface absorption maximum was observed at 590 nm. X-ray diffraction (XRD analysis showed that the CuNPs@NCC are of a face-centered cubic structure. Moreover, the morphology of the CuNPs@NCC was investigated using transmission electron microscope (TEM and field emission scanning electron microscope (FESEM, which showed well-dispersed CuNPs with an average particle size less than 4 nm and the shape of CuNPs was found to be spherical. Energy dispersive X-ray spectroscope (EDS also confirmed the presence of CuNPs on the NCC. The results demonstrate that the stability of CuNPs decreases with an increasing concentration of the copper ions.

  15. Nanocrystalline Aluminum Truss Cores for Lightweight Sandwich Structures

    Science.gov (United States)

    Schaedler, Tobias A.; Chan, Lisa J.; Clough, Eric C.; Stilke, Morgan A.; Hundley, Jacob M.; Masur, Lawrence J.

    2017-12-01

    Substitution of conventional honeycomb composite sandwich structures with lighter alternatives has the potential to reduce the mass of future vehicles. Here we demonstrate nanocrystalline aluminum-manganese truss cores that achieve 2-4 times higher strength than aluminum alloy 5056 honeycombs of the same density. The scalable fabrication approach starts with additive manufacturing of polymer templates, followed by electrodeposition of nanocrystalline Al-Mn alloy, removal of the polymer, and facesheet integration. This facilitates curved and net-shaped sandwich structures, as well as co-curing of the facesheets, which eliminates the need for extra adhesive. The nanocrystalline Al-Mn alloy thin-film material exhibits high strength and ductility and can be converted into a three-dimensional hollow truss structure with this approach. Ultra-lightweight sandwich structures are of interest for a range of applications in aerospace, such as fairings, wings, and flaps, as well as for the automotive and sports industries.

  16. Plasticity-induced restructuring of a nanocrystalline grain boundary network

    International Nuclear Information System (INIS)

    Panzarino, Jason F.; Pan, Zhiliang; Rupert, Timothy J.

    2016-01-01

    The grain boundary-mediated mechanisms that control plastic deformation of nanocrystalline metals should cause evolution of the grain boundary network, since they directly alter misorientation relationships between crystals. Unfortunately, current experimental techniques are unable to track such evolution, due to limits on both spatial and temporal resolution. In this work, molecular dynamics simulations are used to study grain boundary restructuring in nanocrystalline Al during both monotonic tension and cyclic loading. This task is enabled by the creation of new analysis tools for atomistic datasets that allow for a complete characterization and tracking of microstructural descriptors of the grain boundary network. Quantitative measurements of grain boundary character distribution, triple junction type, grain boundary plane normal, and other interfacial network characteristics are extracted and analyzed. The results presented here show that nanocrystalline plasticity leads to an increase in special boundary fraction and disruption of two-dimensional boundary connectivity, with the most dramatic evolution occurring in the smallest grain sizes.

  17. Deposition and characterization of ZnSe nanocrystalline thin films

    Science.gov (United States)

    Temel, Sinan; Gökmen, F. Özge; Yaman, Elif; Nebi, Murat

    2018-02-01

    ZnSe nanocrystalline thin films were deposited at different deposition times by using the Chemical Bath Deposition (CBD) technique. Effects of deposition time on structural, morphological and optical properties of the obtained thin films were characterized. X-ray diffraction (XRD) analysis was used to study the structural properties of ZnSe nanocrystalline thin films. It was found that ZnSe thin films have a cubic structure with a preferentially orientation of (111). The calculated average grain size value was about 28-30 nm. The surface morphology of these films was studied by the Field Emission Scanning Electron Microscope (FESEM). The surfaces of the thin films were occurred from small stacks and nano-sized particles. The band gap values of the ZnSe nanocrystalline thin films were determined by UV-Visible absorption spectrum and the band gap values were found to be between 2.65-2.86 eV.

  18. Creep behavior of a nanocrystalline Fe-B-Si alloy

    International Nuclear Information System (INIS)

    Xiao, M.; Kong, Q.P.

    1997-01-01

    The research of nanocrystalline materials has attracted much attention in the world. In recent years, there have been several studies on their creep behavior. Among these, the authors have studied the tensile creep of a nanocrystalline Ni-P alloy (28 nm) at temperatures around 0.5 Tm (Tm is the melting point). The samples were prepared by the method of crystallization of amorphous ribbon. Based on the data of stress exponent and activation energy, they suggested that the creep was controlled by boundary diffusion; while the creep of the same alloy with a larger grain size (257 nm) was controlled by a different mechanism. In the present paper, the authors extend the research to the creep of a nanocrystalline Fe-B-Si alloy. The samples are also prepared by crystallization of amorphous ribbon. The samples such prepared have an advantage that the interfaces are naturally formed without artificial compaction and porosity

  19. Perceived Satisfaction With Long-Term Oxygen Delivery Devices Affects Perceived Mobility and Quality of Life of Oxygen-Dependent Individuals With COPD.

    Science.gov (United States)

    Mussa, Constance C; Tonyan, Laura; Chen, Yi-Fan; Vines, David

    2018-01-01

    Although routine physical activity for individuals with COPD is recommended, there are inherent limitations of available oxygen delivery devices that may result in hypoxemia during activity. Changes in Medicare laws have resulted in an increased use of oxygen cylinders and a reduction in the use of liquid oxygen devices. The aim of this survey was to assess the impact of perceived satisfaction with various oxygen delivery devices on perceived mobility and quality of life (QOL) of oxygen-dependent subjects with COPD. A survey was developed to measure perceived satisfaction with current portable oxygen delivery devices, perceived mobility, and perceived QOL. The survey was deployed via a link posted on the COPD Foundation's COPD360SOCIAL social media site for 5 weeks, which resulted in the recruitment of 529 participants, of which 417 were included in the data analysis. Quantile regression analysis revealed that the median perceived device satisfaction score was significantly higher in the liquid oxygen device group ( P mobility score was significantly higher in the liquid oxygen device group ( P mobility is significantly affected by perceived satisfaction with the long-term oxygen therapy (LTOT) device (adjusted R 2 = 0.15, P mobility (adjusted R 2 = 0.45, P mobility and QOL. Copyright © 2018 by Daedalus Enterprises.

  20. Nanocrystalline Iron-Cobalt Alloys for High Saturation Indutance

    Science.gov (United States)

    2016-02-24

    AFRL-AFOSR-VA-TR-2016-0263 Nanocrystalline Iron- Cobalt Alloys for High saturation Indutance Conrad Williams MORGAN STATE UNIVERSITY (INC) 1700 E...YYYY) 28-02-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) 01 March 2013 -28 February 2016 4. TITLE AND SUBTITLE Nanocrystalline Iron- Cobalt ...driving the research at Morgan State University is “Can one achieve high magnetization (B > 1.7 T) at low fields (H < 1 mT) in iron- cobalt

  1. Production of nanocrystalline metal powders via combustion reaction synthesis

    Science.gov (United States)

    Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.; Kim, Jin Yong

    2017-10-31

    Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

  2. Texture-dependent twin formation in nanocrystalline thin Pd films

    International Nuclear Information System (INIS)

    Wang, B.; Idrissi, H.; Shi, H.; Colla, M.S.; Michotte, S.; Raskin, J.P.; Pardoen, T.; Schryvers, D.

    2012-01-01

    Nanocrystalline Pd films were produced by electron-beam evaporation and sputter deposition. The electron-beam-evaporated films reveal randomly oriented nanograins with a relatively high density of growth twins, unexpected in view of the high stacking fault energy of Pd. In contrast, sputter-deposited films show a clear 〈1 1 1〉 crystallographic textured nanostructure without twins. These results provide insightful information to guide the generation of microstructures with enhanced strength/ductility balance in high stacking fault energy nanocrystalline metallic thin films.

  3. Improve oxidation resistance at high temperature by nanocrystalline surface layer

    OpenAIRE

    Xia, Z. X.; Zhang, C.; Huang, X. F.; Liu, W. B.; Yang, Z. G.

    2015-01-01

    An interesting change of scale sequence occurred during oxidation of nanocrystalline surface layer by means of a surface mechanical attrition treatment. The three-layer oxide structure from the surface towards the matrix is Fe3O4, spinel FeCr2O4 and corundum (Fe,Cr)2O3, which is different from the typical two-layer scale consisted of an Fe3O4 outer layer and an FeCr2O4 inner layer in conventional P91 steel. The diffusivity of Cr, Fe and O is enhanced concurrently in the nanocrystalline surfac...

  4. Synthesis and Characterization of Nanocrystalline Hydroxyapatite by Combustion Method

    International Nuclear Information System (INIS)

    Yin Thu Aye; Su Su Hlaing; Phyu Sin Khaing Oo; Khin Lay Thwe; Nwe Ni Khin

    2011-12-01

    Among various biocompatible materials hydroxyapatite (HAP) is widely used in medical applications.As nanocrystalline Hydroxyapatite is similar in composition and crystal structure of natural bone it can be used as temporary substitute materials for human bone. A simple combustion technique for synthesizing nanocrystalline hydroxyapatite powder from eggshell has been carried out. The resulting powder was characterized using XRD, SEM and FESEM measurements. The particle size was calculated by Debye-Scherrer equation using XRD data. The range of size of resultant HAP powder was between 23nm-75nm. The average particle size was 34 nm.

  5. Construction, application and biosafety of silver nanocrystalline chitosan wound dressing.

    Science.gov (United States)

    Lu, Shuangyun; Gao, Wenjuan; Gu, Hai Ying

    2008-08-01

    A novel wound dressing composed of nano-silver and chitosan was fabricated using a nanometer and self-assembly technology. Sterility and pyrogen testing assessed biosafety, and efficacy was evaluated using Sprague-Dawley rats with deep partial-thickness wounds. Silver sulfadiazine and chitosan film dressings were used as controls. At intervals wound areas were measured, wound tissues biopsied and blood samples taken. Compared with the controls, the silver nanocrystalline chitosan dressing significantly (psilver levels in blood and tissues lower than levels associated with the silver sulfadiazine dressing (psilver nanocrystalline chitosan dressing were negative. Thus this dressing should have wide application in clinical settings.

  6. Inter- and intra-agglomerate fracture in nanocrystalline nickel.

    Science.gov (United States)

    Shan, Zhiwei; Knapp, J A; Follstaedt, D M; Stach, E A; Wiezorek, J M K; Mao, S X

    2008-03-14

    In situ tensile straining transmission electron microscopy tests have been carried out on nanocrystalline Ni. Grain agglomerates (GAs) were found to form very frequently and rapidly ahead of an advancing crack with sizes much larger than the initial average grain size. High-resolution electron microscopy indicated that the GAs most probably consist of nanograins separated by low-angle grain boundaries. Furthermore, both inter- and intra-GA fractures were observed. The observations suggest that these newly formed GAs may play an important role in the formation of the dimpled fracture surfaces of nanocrystalline materials.

  7. A maximum in the strength of nanocrystalline copper

    DEFF Research Database (Denmark)

    Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2003-01-01

    We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15...... nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence...

  8. NOTE: Optical devices used for image analysis of pigmented skin lesions: a proposal for quality assurance protocol using tissue-like phantoms

    Science.gov (United States)

    Lualdi, M.; Colombo, A.; Carrara, M.; Scienza, L.; Tomatis, S.; Marchesini, R.

    2006-12-01

    Different technological tools have been developed to aid in the diagnosis of pigmented skin lesions, including cameras working with conventional RGB colour systems, epiluminescence microscopy and spectrophotometric methods using visible and near infrared wavelengths. All the different procedures should provide in an objective and reproducible fashion quantitative measurements of the colour and shape features of a given skin mole. At present, many devices have been introduced in experimental stages for clinical diagnosis, mainly used to provide to the clinicians an objective, computer-assisted second opinion. As for any diagnostic instruments, optical devices should also be subjected to a dedicated quality assurance protocol in order to evaluate the response repeatability of each device (intra-instrument agreement) and to check the accordance among the responses of different devices (inter-instrument agreement). The aim of this study was to design a quality assurance protocol for optical devices dedicated to image analysis of pigmented skin lesions and, in case, to detect cutaneous melanoma by using suitable tissue-like phantoms as standard references that enable testing of both hardware and software components. As an example, we report the results of intra-instrument and inter-instrument agreement when the protocol was applied on a series of 30 SpectroShade® instruments, a novel optical device based on multi-spectral image analysis of colour and shape features of pigmented skin lesion.

  9. Development and evaluation of multi-energy PbO dosimeter for quality assurance of image-guide radiation therapy devices

    Science.gov (United States)

    Kim, Kyo-Tae; Heo, Ye-Ji; Han, Moo-Jae; Oh, Kyung-Min; Lee, Young-Kyu; Kim, Shin-Wook; Park, Sung-Kwang

    2017-04-01

    In radiation therapy, accurate radiotherapy treatment plan (RTP) reproduction is necessary to optimize the clinical results. Thus, attempts have recently been made to ensure high RTP reproducibility using image-guide radiation therapy (IGRT) technology. However, the clinical use of digital X-ray equipment requires extended quality assurance (QA) for those devices, since the IGRT device quality determines the precision of intensity-modulated radiation therapy. The study described in this paper was focused on developing a multi-energy PbO dosimeter for IGRT device QA. The Schottky-type polycrystalline PbO dosimeter with a Au/PbO/ITO structure was evaluated by comparing its response coincidence, dose linearity, measurement reproducibility, linear attenuation coefficient, and percent depth dose with those of Si diode and standard ionization chamber dosimeters.

  10. The Effect of the Usage of Computer-Based Assistive Devices on the Functioning and Quality of Life of Individuals Who Are Blind or Have Low Vision

    Science.gov (United States)

    Rosner, Yotam; Perlman, Amotz

    2018-01-01

    Introduction: The Israel Ministry of Social Affairs and Social Services subsidizes computer-based assistive devices for individuals with visual impairments (that is, those who are blind or have low vision) to assist these individuals in their interactions with computers and thus to enhance their independence and quality of life. The aim of this…

  11. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Moteabbed, Maryam; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-01-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D mean ) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D mean and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D mean and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  12. Polarization dependent asymmetric magneto-resistance features in nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Bhattacharyya, Somnath; Churochkin, Dmitry

    2014-01-01

    Polar angle-dependence of magneto-resistance (AMR) in heavily nitrogen-incorporated ultra-nanocrystalline diamond (UNCD) films is recorded by applying high magnetic fields, which shows strong anisotropic features at low temperatures. The temperature-dependence of MR and AMR can reveal transport in the weak-localization regime, which is explained by using a superlattice model for arbitrary values of disorder and angles. While a propagative Fermi surface model explains the negative MR features for low degree of disorder the azimuthal angle-dependent MR shows field dependent anisotropy due to the aligned conducting channels on the layers normal to film growth direction. The analysis of MR and AMR can extract the temperature dependence of dephasing time with respect to the elastic scattering time which not only establishes quasi-two dimensional features in this system but also suggests a potential application in monitoring the performance of UNCD based quantum devices.

  13. Guided assembly of nanoparticles on electrostatically charged nanocrystalline diamond thin films

    Directory of Open Access Journals (Sweden)

    Verveniotis Elisseos

    2011-01-01

    Full Text Available Abstract We apply atomic force microscope for local electrostatic charging of oxygen-terminated nanocrystalline diamond (NCD thin films deposited on silicon, to induce electrostatically driven self-assembly of colloidal alumina nanoparticles into micro-patterns. Considering possible capacitive, sp2 phase and spatial uniformity factors to charging, we employ films with sub-100 nm thickness and about 60% relative sp2 phase content, probe the spatial material uniformity by Raman and electron microscopy, and repeat experiments at various positions. We demonstrate that electrostatic potential contrast on the NCD films varies between 0.1 and 1.2 V and that the contrast of more than ±1 V (as detected by Kelvin force microscopy is able to induce self-assembly of the nanoparticles via coulombic and polarization forces. This opens prospects for applications of diamond and its unique set of properties in self-assembly of nano-devices and nano-systems.

  14. Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation

    Directory of Open Access Journals (Sweden)

    Silviya Mikhailovna Ojovan

    2014-06-01

    Full Text Available Using a variety of proliferating cell types, it was shown that the surface of nanocrystalline-diamond (NCD provides a permissive substrate for cell adhesion and development without the need of complex chemical functionalization prior to cell seeding. In an extensive series of experiments we found that, unlike proliferating cells, post-mitotic primary neurons do not adhere to bare NCD surfaces when cultured in defined medium. These observations raise questions on the potential use of bare NCD as an interfacing layer for neuronal devices. Nevertheless, we also found that classical chemical functionalization methods render the hostile bare NCD surfaces with adhesive properties that match those of classically functionalized substrates used extensively in biomedical research and applications. Based on the results, we propose a mechanism that accounts for the conflicting results; which on one hand claim that un-functionalized NCD provides a permissive substrate for cell adhesion and growth, while other reports demonstrate the opposite.

  15. Optical sensing system based on wireless paired emitter detector diode device and ionogels for lab-on-a-disc water quality analysis.

    Science.gov (United States)

    Czugala, Monika; Gorkin, Robert; Phelan, Thomas; Gaughran, Jennifer; Curto, Vincenzo Fabio; Ducrée, Jens; Diamond, Dermot; Benito-Lopez, Fernando

    2012-12-07

    This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor, is applied for quantitative pH and qualitative turbidity monitoring of water samples at point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems.

  16. Non-monotonic size dependence of the elastic modulus of nanocrystalline ZnO embedded in a nanocrystalline silver matrix

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Vinod; Ghosh, Shankar; Gohil, Smita; Kulkarni, Nilesh; Ayyub, Pushan [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai-400005 (India)

    2008-08-27

    We present the first high pressure Raman study of nanocrystalline ZnO with different average crystallite sizes. The problem of low Raman signals from nanometer-sized particles was overcome by forming a nanocomposite of Ag and ZnO nanoparticles. The presence of the nanodispersed Ag particles leads to a substantial surface enhancement of the Raman signal from ZnO. We find that the elastic modulus of nanocrystalline ZnO shows a non-monotonic dependence on the crystallite size and suggest that the non-monotonicity arises from an interplay between the elastic properties of the individual grains and the intergranular region.

  17. Enhanced quality thin film Cu(In,Ga)Se.sub.2 for semiconductor device applications by vapor-phase recrystallization

    Science.gov (United States)

    Tuttle, John R.; Contreras, Miguel A.; Noufi, Rommel; Albin, David S.

    1994-01-01

    Enhanced quality thin films of Cu.sub.w (In,Ga.sub.y)Se.sub.z for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu.sub.x Se on a substrate to form a large-grain precursor and then converting the excess Cu.sub.x Se to Cu(In,Ga)Se.sub.2 by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga).sub.y Se.sub.z. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300.degree.-600.degree. C., where the Cu(In,Ga)Se.sub.2 remains solid, while the excess Cu.sub.x Se is in a liquid flux. The characteristic of the resulting Cu.sub.w (In,Ga).sub.y Se.sub.z can be controlled by the temperature. Higher temperatures, such as 500.degree.-600.degree. C., result in a nearly stoichiometric Cu(In,Ga)Se.sub.2, whereas lower temperatures, such as 300.degree.-400.degree. C., result in a more Cu-poor compound, such as the Cu.sub.z (In,Ga).sub.4 Se.sub.7 phase.

  18. Enhanced quality thin film Cu(In,Ga)Se[sub 2] for semiconductor device applications by vapor-phase recrystallization

    Science.gov (United States)

    Tuttle, J.R.; Contreras, M.A.; Noufi, R.; Albin, D.S.

    1994-10-18

    Enhanced quality thin films of Cu[sub w](In,Ga[sub y])Se[sub z] for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu[sub x]Se on a substrate to form a large-grain precursor and then converting the excess Cu[sub x]Se to Cu(In,Ga)Se[sub 2] by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga)[sub y]Se[sub z]. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300--600 C, where the Cu(In,Ga)Se[sub 2] remains solid, while the excess Cu[sub x]Se is in a liquid flux. The characteristic of the resulting Cu[sub w](In,Ga)[sub y]Se[sub z] can be controlled by the temperature. Higher temperatures, such as 500--600 C, result in a nearly stoichiometric Cu(In,Ga)Se[sub 2], whereas lower temperatures, such as 300--400 C, result in a more Cu-poor compound, such as the Cu[sub z](In,Ga)[sub 4]Se[sub 7] phase. 7 figs.

  19. Copper removal using electrosterically stabilized nanocrystalline cellulose.

    Science.gov (United States)

    Sheikhi, Amir; Safari, Salman; Yang, Han; van de Ven, Theo G M

    2015-06-03

    Removal of heavy metal ions such as copper using an efficient and low-cost method with low ecological footprint is a critical process in wastewater treatment, which can be achieved in a liquid phase using nanoadsorbents such as inorganic nanoparticles. Recently, attention has turned toward developing sustainable and environmentally friendly nanoadsorbents to remove heavy metal ions from aqueous media. Electrosterically stabilized nanocrystalline cellulose (ENCC), which can be prepared from wood fibers through periodate/chlorite oxidation, has been shown to have a high charge content and colloidal stability. Here, we show that ENCC scavenges copper ions by different mechanisms depending on the ion concentration. When the Cu(II) concentration is low (C0≲200 ppm), agglomerates of starlike ENCC particles appear, which are broken into individual starlike entities by shear and Brownian motion, as evidenced by photometric dispersion analysis, dynamic light scattering, and transmission electron microscopy. On the other hand, at higher copper concentrations, the aggregate morphology changes from starlike to raftlike, which is probably due to the collapse of protruding dicarboxylic cellulose (DCC) chains and ENCC charge neutralization by copper adsorption. Such raftlike structures result from head-to-head and lateral aggregation of neutralized ENCCs as confirmed by transmission electron microscopy. As opposed to starlike aggregates, the raftlike structures grow gradually and are prone to sedimentation at copper concentrations C0≳500 ppm, which eliminates a costly separation step in wastewater treatment processes. Moreover, a copper removal capacity of ∼185 mg g(-1) was achieved thanks to the highly charged DCC polyanions protruding from ENCC. These properties along with the biorenewability make ENCC a promising candidate for wastewater treatment, in which fast, facile, and low-cost removal of heavy metal ions is desired most.

  20. Ferromagnetic resonance in bulk nanocrystalline Ni

    Science.gov (United States)

    Prakash Madduri, P. V.; Mathew, S. P.; Kaul, S. N.

    2018-03-01

    A detailed lineshape analysis of the ferromagnetic resonance (FMR) spectra taken on pulse electrodeposited nanocrystalline (nc-) Ni sheets (with the average crystallite size, d, varying from 10 nm to 40 nm) at temperatures ranging from 113 K to 325 K yield accurate values for saturation magnetization, Ms (T), Landé splitting factor, g, anisotropy field, Hk (T) , resonance field, Hres , and FMR linewidth, ΔHpp (T) . Thermally-excited spin-wave (SW) excitations completely account for Ms (T) and the SW description of Ms (T) gives the values for the saturation magnetization and spin-wave stiffness at absolute zero of temperature, i.e., Ms (0) and D0 , for nc-Ni samples of different d that are in excellent agreement with the corresponding values deduced previously from an elaborate SW analysis of the bulk magnetization data. While Ms (0) varies with d as Ms (0) d - 3 / 2,D0 follows the power law D0 ∼d 4 / 3 . The angular variations of Hres in the 'in-plane' as well as 'out-of-plane' sample configurations, demonstrate that the main contribution to Hk (T) comes from the cubic magnetocrystalline anisotropy. The exchange-conductivity mechanism describes the observed thermal decline of ΔHpp reasonably well but fails to explain the very large magnitude of ΔHpp at any given temperature. By comparison, the Landau-Lifshitz-Gilbert (LLG) damping gives a much greater contribution to ΔHpp but the LLG contribution is relatively insensitive to temperature.

  1. Low power optical limiting studies on nanocrystalline benzimidazole ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 3. Low power optical limiting studies on nanocrystalline benzimidazole thin films prepared by modified liquid phase growth technique. P A Praveen S P Prabhakaran R Ramesh Babu K Sethuraman K Ramamurthi. Volume 38 Issue 3 June 2015 pp 645-651 ...

  2. Adhesion of osteoblasts on chemically patterned nanocrystalline diamonds

    Czech Academy of Sciences Publication Activity Database

    Kalbáčová, M.; Michalíková, Lenka; Barešová, V.; Kromka, Alexander; Rezek, Bohuslav; Kmoch, S.

    2008-01-01

    Roč. 245, č. 10 (2008), s. 2124-2127 ISSN 0370-1972 R&D Projects: GA AV ČR KAN400100701 Institutional research plan: CEZ:AV0Z10100521 Keywords : cell growth * nanocrystalline diamond * surface termination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.166, year: 2008

  3. High-pressure structural behavior of nanocrystalline Ge

    DEFF Research Database (Denmark)

    Wang, H.; Liu, J. F.; Yan, H.

    2007-01-01

    The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse...

  4. High temperature magnetic properties of nanocrystalline Sn0 ...

    Indian Academy of Sciences (India)

    Administrator

    National School of Applied Sciences, Safi, Morocco. 5Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9, France. MS received 17 October 2012; revised 17 December 2012. Abstract. Structural and magnetic properties of Sn0⋅95Co0⋅05O2 nanocrystalline and diluted magnetic semicon-.

  5. Bioactive nanocrystalline wollastonite synthesized by sol–gel ...

    Indian Academy of Sciences (India)

    The sol–gel combustion method was employed to synthesize the nanocrystalline wollastonite by taking the raw eggshell powder as a calcium source and TEOS as a source of silicate. Glycine was used as a reductant or fuel and nitrate ions present in metal nitrate acts as an oxidizer. The phase purity of the wollastonite was ...

  6. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    Both beneficial as well as detrimental effects of the nanocrystalline coatings have been reported and the pro- perties of coating can be influenced by many factors such as grain size and its distribution, surface condition, adhe- rence to the substrate, reactivity with the medium and its pre- paration routes, etc (Szewieczek et al ...

  7. A Low Temperature Synthetic Route to Nanocrystalline TiN

    African Journals Online (AJOL)

    NICO

    A simple chemical synthetic route has been developed to prepare nanocrystalline titanium nitride (TiN) in an autoclave, by the reaction of metallic Ti with NaNH2 at low temperature of 500–600 °C. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron ...

  8. Nanocrystalline nickel as a material with high hydrogen storage capacity

    Czech Academy of Sciences Publication Activity Database

    Vojtěch, D.; Michalcová, A.; Klementová, Mariana; Šerák, J.; Morťaniková, M.

    2009-01-01

    Roč. 63, č. 12 (2009), s. 1074-1076 ISSN 0167-577X Institutional research plan: CEZ:AV0Z40320502 Keywords : electron microscopy * nanomaterials * nano-crystalline nickel Subject RIV: CA - Inorganic Chemistry Impact factor: 1.940, year: 2009

  9. Nanocrystalline spinel ferrites by solid state reaction route

    Indian Academy of Sciences (India)

    Wintec

    Nanocrystalline spinel ferrites by solid state reaction route. T K KUNDU* and S MISHRA. Department of Physics, Visva-Bharati, Santiniketan 731 235, India. Abstract. Nanostructured NiFe2O4, MnFe2O4 and (NiZn)Fe2O4 were synthesized by aliovalent ion doping using conventional solid-state reaction route. With the ...

  10. Quartz crystal microbalance gas sensor with nanocrystalline diamond sensitive layer

    Czech Academy of Sciences Publication Activity Database

    Varga, Marián; Laposa, A.; Kulha, Pavel; Kroutil, J.; Husák, M.; Kromka, Alexander

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2591-2597 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : gas sensor * nanocrystalline diamond * quartz resonator * thickness shear mode Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.522, year: 2015

  11. Transparent nanocrystalline ZnO films prepared by spin coating

    International Nuclear Information System (INIS)

    Berber, M.; Bulto, V.; Kliss, R.; Hahn, H.

    2005-01-01

    Dispersions of zinc oxide nanoparticles synthesized by the electrochemical deposition under oxidizing conditions process with organic surfactants, were spin coated on glass substrates. After sintering, the microstructure, surface morphology, and electro-optical properties of the transparent nanocrystalline zinc oxide films have been investigated for different coating thicknesses and organic solvents

  12. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Directory of Open Access Journals (Sweden)

    Amel Bendali

    Full Text Available Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  13. Low power optical limiting studies on nanocrystalline benzimidazole ...

    Indian Academy of Sciences (India)

    Low power optical limiting studies on nanocrystalline benzimidazole thin films prepared by modified liquid phase growth technique. P A PRAVEEN1, S P PRABHAKARAN1, R RAMESH BABU1,∗, K SETHURAMAN2 and K RAMAMURTHI3. 1Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan ...

  14. Synthesis of nanocrystalline mixed metal fluorides in nonaqueous ...

    Indian Academy of Sciences (India)

    Administrator

    Synthesis of nanocrystalline mixed metal fluorides in nonaqueous medium. NEETU TYAGI, EPSITA GHANTI, NIKESH GUPTA, N P LALLA. † and. RAJAMANI NAGARAJAN*. Department of Chemistry, University of Delhi, Delhi 110 007, India. †. Inter University Consortium for DAE Facilities, University Campus, Indore 452 ...

  15. Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn^(2+)

    NARCIS (Netherlands)

    Suyver, J.F.; Wuister, S.F.; Kelly, J.J.; Meijerink, A.

    2001-01-01

    The influence of the synthesis conditions on the properties of nanocrystalline ZnS:Mn2+ is discussed. Different Mn2+ precursors and different ratios of the precursor concentrations [S2-]/[Zn2+] were used. The type of Mn2+ precursor does not have an effect on the luminescence properties in the

  16. Pulsed nanocrystalline plasma electrolytic boriding as a novel ...

    Indian Academy of Sciences (India)

    The effect of frequency and duty cycle of pulsed current was investigated. It was found that pulse frequency and duty cycle affect the size and porosity of nanocrystalline borides and by controlling these effective parameters, surface modification can render the CP-Ti material extremely corrosion resistant as a biomaterial.

  17. Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

    Energy Technology Data Exchange (ETDEWEB)

    Z. Zak Fang, H. Y. Sohn

    2009-03-10

    This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

  18. Osteoblastic cells trigger gate currents on nanocrystalline diamond transistor

    Czech Academy of Sciences Publication Activity Database

    Ižák, Tibor; Krátká, Marie; Kromka, Alexander; Rezek, Bohuslav

    2015-01-01

    Roč. 129, May (2015), 95-99 ISSN 0927-7765 R&D Projects: GA ČR GAP108/12/0996 Grant - others:AVČR(CZ) M100101209 Institutional support: RVO:68378271 Keywords : field-effect transistors * nanocrystalline diamond * osteoblastic cells * leakage currents Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.902, year: 2015

  19. Nanocrystalline diamond surface functionalization in radio frequency plasma

    Czech Academy of Sciences Publication Activity Database

    Remeš, Zdeněk; Choukourov, A.; Stuchlík, Jiří; Potměšil, Jiří; Vaněček, Milan

    2006-01-01

    Roč. 15, - (2006), s. 745-748 ISSN 0925-9635 R&D Projects: GA ČR(CZ) GA202/05/2233; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : diamond film * nanocrystalline * coatings * biomedical applications Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.935, year: 2006

  20. High Pressure X-Ray Diffraction Studies on Nanocrystalline Materials

    Science.gov (United States)

    Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Pielaszek, R.; Bismayer, U.; Werner, S.; Palosz, W.

    2003-01-01

    Application of in situ high pressure powder diffraction technique for examination of specific structural properties of nanocrystals based on the experimental data of SiC nanocrystalline powders of 2 to 30 nrn diameter in diameter is presented. Limitations and capabilities of the experimental techniques themselves and methods of diffraction data elaboration applied to nanocrystals with very small dimensions (nanoparticles of different grain size.

  1. Fast response time alcohol gas sensor using nanocrystalline F ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Fast response time alcohol gas sensor using nanocrystalline F-doped SnO2 films derived via sol–gel method. Sarbani Basu Yeong-Her Wang C Ghanshyam Pawan Kapur. Volume 36 Issue 4 August 2013 pp 521-533 ...

  2. High temperature magnetic properties of nanocrystalline Sn0 ...

    Indian Academy of Sciences (India)

    Administrator

    High temperature magnetic properties of nanocrystalline Sn0⋅95Co0⋅05O2. O MOUNKACHI1, E SALMANI2, ... exchange interaction between the magnetic ions and the band electrons. Tin dioxide (SnO2) is an n-type ... rate must be well controlled for the chemical homogene- ity. The reactants were constantly stirred using ...

  3. Oxygen reduction on nanocrystalline ruthenia-local structure effects

    DEFF Research Database (Denmark)

    Abbott, Daniel F.; Mukerjee, Sanjeev; Petrykin, Valery

    2015-01-01

    Nanocrystalline ruthenium dioxide and doped ruthenia of the composition Ru1-xMxO2 (M = Co, Ni, Zn) with 0 ≤ x ≤ 0.2 were prepared by the spray-freezing freeze-drying technique. The oxygen reduction activity and selectivity of the prepared materials were evaluated in alkaline media using the RRDE ...

  4. Burstein Moss effect in nanocrystalline CaS: Ce

    Indian Academy of Sciences (India)

    Administrator

    Burstein Moss effect in nanocrystalline CaS: Ce. GEETA SHARMA*, PUJA CHAWLA, S P LOCHAB. † and NAFA SINGH. Department of Physics, Kurukshetra University, Kurukshetra 136 119, India. †. Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India. MS received 27 July 2009; revised 16 ...

  5. Surface plasmon effect in nanocrystalline copper/DLC composite ...

    Indian Academy of Sciences (India)

    Composite films of nanocrystalline copper embedded in DLC matrix prepared by electrodeposition technique were studied for their optical properties. Particle size and metal volume fractions were tailored by varying the amount of copper containing salt in the electrolyte. Blue-shift of the surface plasmon resonance peak in ...

  6. Distinctive glial and neuronal interfacing on nanocrystalline diamond.

    Science.gov (United States)

    Bendali, Amel; Agnès, Charles; Meffert, Simone; Forster, Valérie; Bongrain, Alexandre; Arnault, Jean-Charles; Sahel, José-Alain; Offenhäusser, Andreas; Bergonzo, Philippe; Picaud, Serge

    2014-01-01

    Direct electrode/neuron interfacing is a key challenge to achieve high resolution of neuronal stimulation required for visual prostheses. Neuronal interfacing on biomaterials commonly requires the presence of glial cells and/or protein coating. Nanocrystalline diamond is a highly mechanically stable biomaterial with a remarkably large potential window for the electrical stimulation of tissues. Using adult retinal cell cultures from rats, we found that glial cells and retinal neurons grew equally well on glass and nanocrystalline diamond. The use of a protein coating increased cell survival, particularly for glial cells. However, bipolar neurons appeared to grow even in direct contact with bare diamond. We investigated whether the presence of glial cells contributed to this direct neuron/diamond interface, by using purified adult retinal ganglion cells to seed diamond and glass surfaces with and without protein coatings. Surprisingly, these fully differentiated spiking neurons survived better on nanocrystalline diamond without any protein coating. This greater survival was indicated by larger cell numbers and the presence of longer neurites. When a protein pattern was drawn on diamond, neurons did not grow preferentially on the coated area, by contrast to their behavior on a patterned glass. This study highlights the interesting biocompatibility properties of nanocrystalline diamond, allowing direct neuronal interfacing, whereas a protein coating was required for glial cell growth.

  7. Fast response time alcohol gas sensor using nanocrystalline F

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 4. Fast response time alcohol gas sensor using nanocrystalline F-doped SnO2 films derived via sol–gel method. Sarbani Basu Yeong-Her Wang C Ghanshyam Pawan Kapur. Volume 36 Issue 4 August 2013 pp 521-533 ...

  8. Fast response time alcohol gas sensor using nanocrystalline F ...

    Indian Academy of Sciences (India)

    Fast response time alcohol gas sensor using nanocrystalline F-doped. SnO2 films derived via sol–gel method. SARBANI BASU, YEONG-HER WANG†, C GHANSHYAM. ∗ and PAWAN KAPUR. CSIR-Central Scientific Instruments Organisation, Sector-30, Chandigarh 160 030, India. †Department of Electrical Engineering, ...

  9. Surface-modified nanocrystalline ceramics for drug delivery applications.

    Science.gov (United States)

    Kossovsky, N; Gelman, A; Sponsler, E E; Hnatyszyn, H J; Rajguru, S; Torres, M; Pham, M; Crowder, J; Zemanovich, J; Chung, A

    1994-12-01

    Drug delivery systems comprised of various types of carriers have long been the object of pharmacological investigation. The search has been stimulated by the belief that carriers will lead to reduced drug toxicity, dosage requirements, enhanced cellular targeting and improved shelf-life. Among the carriers investigated are complex polymeric carbohydrates, synthetic proteins and liposomal structures. For the past four years, we have been experimenting with a radically new class of carriers comprised of surface-modified nanocrystalline ceramics. While the ceramics provide the structural stability of a largely immutable solid, the surface modification creates a glassy molecular stabilization film to which pharmacological agents may be bound non-covalently from an aqueous phase with minimal structural denaturation. As a consequence of maintained structural integrity and owing to concentration effects afforded by the surfaces of the nanocrystalline materials, drug activity following surface immobilization is preserved. We have used successfully surface-modified nanocrystalline ceramics to deliver viral antigens for the purpose of evoking an immune response, oxygenated haemoglobin for cell respiration and insulin for carbohydrate metabolism. The theoretical principles, technical details and experimental results are reviewed. Surface-modified nanocrystalline materials offer an exciting new approach to the well-recognized challenges of drug delivery.

  10. Synthesis and visible light photocatalytic activity of nanocrystalline ...

    Indian Academy of Sciences (India)

    The synthesized materials were characterized by XRD, BET-SA, SEM, HRTEM, XPS, FTIR and UV-DRS techniques to understand their physico-chemical properties. Characterization data reveal the formation of nanocrystalline PrFeO3 perovskite composition with improved physical properties, possibly due to lower ...

  11. Gas sensing properties of nanocrystalline diamond at room temperature

    Czech Academy of Sciences Publication Activity Database

    Davydova, Marina; Kulha, P.; Laposa, A.; Hruška, Karel; Demo, Pavel; Kromka, Alexander

    2014-01-01

    Roč. 5, Dec (2014), s. 2339-2345 ISSN 2190-4286 R&D Projects: GA ČR(CZ) GP14-06054P Institutional support: RVO:68378271 Keywords : gas sensor * integrator * interdigitated electrodes * nanocrystalline diamond * response Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.670, year: 2014

  12. Luminescence of nanocrystalline ZnSe:Mn2+

    NARCIS (Netherlands)

    Suyver, J.F.; Wuister, S.F.; Kelly, J.J.; Meijerink, A.

    2000-01-01

    The luminescence properties of nanocrystalline ZnSe:Mn^(2+) prepared via an inorganic chemical synthesis are described. Photoluminescence spectra show distinct ZnSe and Mn^(2+) related emissions, both of which are excited via the ZnSe host lattice. The Mn^(2+) emission wavelength and the

  13. Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, W. Roger

    2006-05-22

    The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

  14. SU-E-T-438: Commissioning of An In-Vivo Quality Assurance Method Using the Electronic Portal Imaging Device

    Energy Technology Data Exchange (ETDEWEB)

    Morin, O; Held, M; Pouliot, J [UC San Francisco, San Francisco, CA (United States)

    2014-06-01

    Purpose: Patient specific pre-treatment quality assurance (QA) using arrays of detectors or film have been the standard approach to assure the correct treatment is delivered to the patient. This QA approach is expensive, labor intensive and does not guarantee or document that all remaining fractions were treated properly. The purpose of this abstract is to commission and evaluate the performance of a commercially available in-vivo QA software using the electronic portal imaging device (EPID) to record the daily treatments. Methods: The platform EPIgray V2.0.2 (Dosisoft), which machine model compares ratios of TMR with EPID signal to predict dose was commissioned for an Artiste (Siemens Oncology Care Systems) and a Truebeam (Varian medical systems) linear accelerator following the given instructions. The systems were then tested on three different phantoms (homogeneous stack of solid water, anthropomorphic head and pelvis) and on a library of patient cases. Simple and complex fields were delivered at different exposures and for different gantry angles. The effects of the table attenuation and the EPID sagging were evaluated. Gamma analysis of the measured dose was compared to the predicted dose for complex clinical IMRT cases. Results: Commissioning of the EPIgray system for two photon energies took 8 hours. The difference between the dose planned and the dose measured with EPIgray was better than 3% for all phantom scenarios tested. Preliminary results on patients demonstrate an accuracy of 5% is achievable in high dose regions for both 3DCRT and IMRT. Large discrepancies (>5%) were observed due to metallic structures or air cavities and in low dose areas. Flat panel sagging was visible and accounted for in the EPIgray model. Conclusion: The accuracy achieved by EPIgray is sufficient to document the safe delivery of complex IMRT treatments. Future work will evaluate EPIgray for VMAT and high dose rate deliveries. This work is supported by Dosisoft, Cachan, France.

  15. Quality of life of lumbar stenosis-treated patients in whom the X STOP interspinous device was implanted.

    Science.gov (United States)

    Hsu, Ken Y; Zucherman, James F; Hartjen, Charles A; Mehalic, Thomas F; Implicito, Dante A; Martin, Michael J; Johnson, Donald R; Skidmore, Grant A; Vessa, Paul P; Dwyer, James W; Cauthen, Joseph C; Ozuna, Richard M

    2006-12-01

    This study was conducted to compare the quality of life (QOL) in patients with neurogenic intermittent claudication (NIC) secondary to lumbar spinal stenosis (LSS). Using the 36-Item Short Form (SF-36) questionnaire, the authors compared the results obtained in patients treated with the X STOP Interspinous Process Decompression (IPD) System with those obtained in patients who underwent nonoperative therapies. Patients with LSS were enrolled in a prospective 2-year multicenter study and randomized either to the X STOP or nonoperative group. The SF-36 survey was used to assess the QOL before treatment and at 6 weeks, 6 months, 1 year, and 2 years posttreatment. An analysis of variance was used to compare individual pre- and posttreatment mean SF-36 domain scores between the two groups and within each treatment group. At all posttreatment time points, the authors observed the following: (1) mean domain scores in X STOP-treated patients were significantly greater than those in patients treated nonoperatively, with the exception of the mean General Health (GH), Role Emotional, and Mental Component Summary scores at 2 years; and (2) mean posttreatment domain scores documented in X STOP-treated patients were significantly greater than mean pretreatment scores, with the exception of mean GH scores at 6, 12, and 24 months. The results of this study demonstrate that the X STOP device is significantly more effective than nonoperative therapy in improving the QOL in patients with LSS. The results are comparable with those reported in other studies involving traditional decompressive techniques for LSS and suggest that the X STOP implant can provide an effective treatment compared with nonoperative and conventional surgical therapies.

  16. Fabrication of an Fe80.5Si7.5B6Nb5Cu Amorphous-Nanocrystalline Powder Core with Outstanding Soft Magnetic Properties

    Science.gov (United States)

    Zhang, Zongyang; Liu, Xiansong; Feng, Shuangjiu; Rehman, Khalid Mehmood Ur

    2018-03-01

    In this study, the melt spinning method was used to develop Fe80.5Si7.5B6Nb5Cu amorphous ribbons in the first step. Then, the Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline core with a compact microstructure was obtained by multiple processes. The main properties of the magnetic powder core, such as micromorphology, thermal behavior, permeability, power loss and quality factor, have been analyzed. The obtained results show that an Fe80.5Si7.5B6Nb5Cu amorphous-nanocrystalline duplex core has high permeability (54.8-57), is relatively stable at different frequencies and magnetic fields, and the maximum power loss is only 313 W/kg; furthermore, it has a good quality factor.

  17. Integration of High-Performance Nanocrystalline TiO2 Photoelectrodes for N719-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Ke-Jian Jiang

    2013-01-01

    Full Text Available We report on enhanced performance of N719-sensitized TiO2 solar cells (DSCs incorporating size and photoelectron diffusion-controlled TiO2 as sensitizer-matched light-scatter layers on conventional nanocrystalline TiO2 electrodes. The double-layered N719/TiO2 composite electrode with a high dye-loading capacity exhibits the diffused reflectance of more than 50% in the range of λ = 650–800 nm, even when the films are coupled with the titania nanocrystalline underlayer in the device. As a result, the increased near-infrared light-harvesting produces a high light-to-electricity conversion efficiency of over 9% mainly due to the significant increase of Jsc. Such an optical effect of the NIR-light scattering TiO2 electrodes will be beneficial when the sensitizers with low molar extinction coefficients, such as N719, are introduced in the device.

  18. NATO Advanced Research Workshop on Properties and Applications of Nanocrystalline Alloys from Amorphous Precursors

    CERN Document Server

    Idzikowski, Bogdan; Miglierini, Marcel

    2005-01-01

    Metallic (magnetic and non-magnetic) nanocrystalline materials have been known for over ten years but only recent developments in the research into those complex alloys and their metastable amorphous precursors have created a need to summarize the most important accomplishments in the field. This book is a collection of articles on various aspects of metallic nanocrystalline materials, and an attempt to address this above need. The main focus of the papers is put on the new issues that emerge in the studies of nanocrystalline materials, and, in particular, on (i) new compositions of the alloys, (ii) properties of conventional nanocrystalline materials, (iii) modeling and simulations, (iv) preparation methods, (v) experimental techniques of measurements, and (vi) different modern applications. Interesting phenomena of the physics of nanocrystalline materials are a consequence of the effects induced by the nanocrystalline structure. They include interface physics, the influence of the grain boundaries, the aver...

  19. Methods for preparation of nanocrystalline rare earth phosphates for lighting applications

    Science.gov (United States)

    Comanzo, Holly Ann; Manoharan, Mohan; Martins Loureiro, Sergio Paulo; Setlur, Anant Achyut; Srivastava, Alok Mani

    2013-04-16

    Disclosed here are methods for the preparation of optionally activated nanocrystalline rare earth phosphates. The optionally activated nanocrystalline rare earth phosphates may be used as one or more of quantum-splitting phosphor, visible-light emitting phosphor, vacuum-UV absorbing phosphor, and UV-emitting phosphor. Also disclosed herein are discharge lamps comprising the optionally activated nanocrystalline rare earth phosphates provided by these methods.

  20. Effect of WC/Co coherency phase boundaries on Fracture toughness of the nanocrystalline cemented carbides

    OpenAIRE

    Hongxian Xie; Xiaoyan Song; Fuxing Yin; Yongguang Zhang

    2016-01-01

    The effect of coherency WC/Co phase boundaries on the fracture toughness of the nanocrystalline WC-Co cemented carbides is studied by MD simulation method. The simulation results show that the nanocrystalline WC-Co cemented carbides with coherency WC/Co phase boundaries has higher fracture toughness than that without coherency WC/Co phase boundaries. Moreover, the mechanism of why coherency WC/Co phase boundaries can improve the fracture toughness of the nanocrystalline cemented carbides is a...

  1. Parking Lot Runoff Quality and Treatment Efficiency of a Stormwater-Filtration Device, Madison, Wisconsin, 2005-07

    Science.gov (United States)

    Horwatich, Judy A.; Bannerman, Roger T.

    2010-01-01

    To evaluate the treatment efficiency of a stormwater-filtration device (SFD) for potential use at Wisconsin Department of Transportation (WisDOT) park-and-ride facilities, a SFD was installed at an employee parking lot in downtown Madison, Wisconsin. This type of parking lot was chosen for the test site because the constituent concentrations and particle-size distributions (PSDs) were expected to be similar to those of a typical park-and-ride lot operated by WisDOT. The objective of this particular installation was to reduce loads of total suspended solids (TSS) in stormwater runoff to Lake Monona. This study also was designed to provide a range of treatment efficiencies expected for a SFD. Samples from the inlet and outlet were analyzed for 33 organic and inorganic constituents, including 18 polycyclic aromatic hydrocarbons (PAHs). Samples were also analyzed for physical properties, including PSD. Water-quality samples were collected for 51 runoff events from November 2005 to August 2007. Samples from all runoff events were analyzed for concentrations of suspended sediment (SS). Samples from 31 runoff events were analyzed for 15 constituents, samples from 15 runoff events were analyzed for PAHs, and samples from 36 events were analyzed for PSD. The treatment efficiency of the SFD was calculated using the summation of loads (SOL) and the efficiency ratio methods. Constituents for which the concentrations and (or) loads were decreased by the SFD include TSS, SS, volatile suspended solids, total phosphorous (TP), total copper, total zinc, and PAHs. The efficiency ratios for these constituents are 45, 37, 38, 55, 22, 5, and 46 percent, respectively. The SOLs for these constituents are 32, 37, 28, 36, 23, 8, and 48 percent, respectively. The SOL for chloride was -21 and the efficiency ratio was -18. Six chemical constituents or properties-dissolved phosphorus, chemical oxygen demand, dissolved zinc, total dissolved solids, dissolved chemical oxygen demand, and

  2. The performance of a prototype device designed to evaluate general quality parameters of X-ray equipment

    International Nuclear Information System (INIS)

    Murata, C.H.; Fernandes, D.C.; Lavínia, N.C.; Caldas, L.V.E; Pires, S.R; Medeiros, R.B.

    2014-01-01

    The performance of radiological equipment can be assessed using non-invasive methods and portable instruments that can analyze an X-ray beam with just one exposure. These instruments use either an ionization chamber or a state solid detector (SSD) to evaluate X-ray beam parameters. In Brazil, no such instruments are currently being manufactured; consequently, these instruments come at a higher cost to users due to importation taxes. Additionally, quality control tests are time consuming and impose a high workload on the X-ray tubes when evaluating their performance parameters. The assessment of some parameters, such as the half-value layer (HVL), requires several exposures; however, this can be reduced by using a SSD that requires only a single exposure. One such SSD uses photodiodes designed for high X-ray sensitivity without the use of scintillation crystals. This sensitivity allows one electron-hole pair to be created per 3.63 eV of incident energy, resulting in extremely high and stable quantum efficiencies. These silicon photodiodes operate by absorbing photons and generating a flow of current that is proportional to the incident power. The aim of this study was to show the response of the solid sensor PIN RD100A detector in a multifunctional X-ray analysis system that is designed to evaluate the average peak voltage (kVp), exposure time, and HVL of radiological equipment. For this purpose, a prototype board that uses four SSDs was developed to measure kVp, exposure time, and HVL using a single exposure. The reproducibility and accuracy of the results were compared to that of different X-ray beam analysis instruments. The kVp reproducibility and accuracy results were 2% and 3%, respectively; the exposure time reproducibility and accuracy results were 2% and 1%, respectively; and the HVL accuracy was ±2%. The prototype's methodology was able to calculate these parameters with appropriate reproducibility and accuracy. Therefore, the prototype can be considered

  3. Effects of procurement practices on quality of medical device or service received: a qualitative study comparing countries.

    Science.gov (United States)

    Lingg, Myriam; Wyss, Kaspar; Durán-Arenas, Luis

    2016-08-08

    We know little about how procurement of a high-risk medical device (HRMD) affects clinical practice and outcomes. In health systems in high-income countries, and specifically those that maintain a national arthroplasty registry, procurement decisions are frequently guided by long-term clinical results, with the goal of ensuring at least standard quality of HRMDs. But in countries like Mexico, decision-making is often dominated by lowest acquisition price. We set out to study the impact of procurement for orthopaedic HRMDs on clinical procedures and outcomes. We based our qualitative study on 59 in-depth interviews with stakeholders from Mexico, Switzerland, Germany, and UK: orthopaedic specialists, government officials, other experts, and social security system managers or administrators. We took a healthcare delivery approach to capturing and comparing factors that affected the regulations of HRMDs and procurement processes, and to understanding connections between procurement and clinical practice. Our findings demonstrate for procurement processes that the three European countries compared to Mexico don't have similar concerns with regards to their procurement processes. Deficiencies of procurement regulations and practices identified from representatives in Mexico were almost absent in European countries. We identified three areas of deficiency: 1) HRMD regulations based on insufficiently robust clinical evidence (mainly noted by European countries); 2) Follow-up on Health Technology Assessments is inadequate (noted by Mexico) and methodology not always good enough (noted by European countries); and, 3) Lowest-acquisition price often guides procurement decisions and thus may not align with needs of clinical procedures (noted by Mexico and some European countries). Procurement processes for orthopaedic HRMDs may have an impact on clinical procedures and outcomes. A favourable approach is one where orthopaedic specialists are parties to the procurement process

  4. The method and device for thermoregulation and optimization of dental material′s quality and working time

    Directory of Open Access Journals (Sweden)

    Sajjad Ashnagar

    2016-01-01

    Full Text Available Introduction: No one can cast a shadow of doubt on the fact that temperature is a key element in dentistry. Temperature control enable dentists in a variety of clinical fields to perform more convenient. Frozen slab is a known method for manipulating temperature before mixing cements. But lack of precise temperature and infection control is bolded. Clinical innovation: The present apparatus determines a method for temperature control in routine dentistry tasks; namely restorative dentistry, prosthesis and even injections. This device is capable of whether heating or cooling materials using low voltage electricity. Peltier or thermoelectric effect is the mechanism behind this device. As operator sets a temperature, device would provide it via metal pads arranged on it in seconds. Discussion: Other common methods used in dentistry have some issues regarding power usage, infection control, size and etc. However, this device is small, cost effective, simple to use and has fast action. Infection control can be actively be maintained with it. This device is a promising alternative for this purpose. Present manuscript summarizes device properties and its potential utilities in dentistry.

  5. Structural, optical and photoluminescence study of nanocrystalline ...

    Indian Academy of Sciences (India)

    Administrator

    formity, nontoxicity, good electrical, low resistivity, sta- bility to heat treatment, mechanical hardness, piezoelectric behaviour and its low cost. SnO2 thin films have vast applications as window layers, heat reflectors in solar cells, flat panel display, electro-chromic devices, LEDs, liquid crystal displays, invisible security circuits, ...

  6. Electromagnetic properties of nanocrystalline Al substituted ...

    Indian Academy of Sciences (India)

    The applicability of present samples for microwave devices has been tested by the measurement of ferromagnetic resonance linewidth at Ka band. ... A is a divalent metal ion (e.g., magnesium, zinc, nickel and cobalt) and B usually iron ... water and absolute ethyl alcohol followed by drying over- night at 80. ◦. C. Then the ...

  7. Paramagnetic centers in nanocrystalline TiC/C system

    International Nuclear Information System (INIS)

    Guskos, N.; Bodziony, T.; Maryniak, M.; Typek, J.; Biedunkiewicz, A.

    2008-01-01

    Electron paramagnetic resonance is applied to study the defect centers in nanocrystalline titanium carbide dispersed in carbon matrix (TiC x /C) synthesized by the non-hydrolytic sol-gel process. The presence of Ti 3+ paramagnetic centers is identified below 120 K along with a minor contribution from localized defect spins coupled with the conduction electron system in the carbon matrix. The temperature dependence of the resonance intensity of the latter signal indicates weak antiferromagnetic interactions. The presence of paramagnetic centers connected with trivalent titanium is suggested to be the result of chemical disorder, which can be further related to the observed anomalous behavior of conductivity, hardness, and corrosion resistance of nanocrystalline TiC x /C

  8. Grain boundary and triple junction diffusion in nanocrystalline copper

    Energy Technology Data Exchange (ETDEWEB)

    Wegner, M., E-mail: m.wegner@uni-muenster.de; Leuthold, J.; Peterlechner, M.; Divinski, S. V., E-mail: divin@uni-muenster.de [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Song, X., E-mail: xysong@bjut.edu.cn [College of Materials Science and Engineering, Beijing University of Technology, 100124 Beijing (China); Wilde, G. [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 200444 Shanghai (China)

    2014-09-07

    Grain boundary and triple junction diffusion in nanocrystalline Cu samples with grain sizes, 〈d〉, of ∼35 and ∼44 nm produced by spark plasma sintering were investigated by the radiotracer method using the {sup 63}Ni isotope. The measured diffusivities, D{sub eff}, are comparable with those determined previously for Ni grain boundary diffusion in well-annealed, high purity, coarse grained, polycrystalline copper, substantiating the absence of a grain size effect on the kinetic properties of grain boundaries in a nanocrystalline material at grain sizes d ≥ 35 nm. Simultaneously, the analysis predicts that if triple junction diffusion of Ni in Cu is enhanced with respect to the corresponding grain boundary diffusion rate, it is still less than 500⋅D{sub gb} within the temperature interval from 420 K to 470 K.

  9. Research Update: Phonon engineering of nanocrystalline silicon thermoelectrics

    Directory of Open Access Journals (Sweden)

    Junichiro Shiomi

    2016-10-01

    Full Text Available Nanocrystalline silicon thermoelectrics can be a solution to improve the cost-effectiveness of thermoelectric technology from both material and integration viewpoints. While their figure-of-merit is still developing, recent advances in theoretical/numerical calculations, property measurements, and structural synthesis/fabrication have opened up possibilities to develop the materials based on fundamental physics of phonon transport. Here, this is demonstrated by reviewing a series of works on nanocrystalline silicon materials using calculations of multiscale phonon transport, measurements of interfacial heat conduction, and synthesis from nanoparticles. Integration of these approaches allows us to engineer phonon transport to improve the thermoelectric performance by introducing local silicon-oxide structures.

  10. Nanocrystalline electrodeposited Ni-Mo-C cathodes for hydrogen production

    International Nuclear Information System (INIS)

    Hashimoto, K.; Sasaki, T.; Meguro, S.; Asami, K.

    2004-01-01

    Tailoring active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. The carbon addition to Ni-Mo alloys decreased the nanocrystalline grain size and remarkably enhanced the activity for hydrogen evolution, changing the mechanism of hydrogen evolution. The Tafel slope of hydrogen evolution was about 35 mV per decade. This suggested that the rate-determining step is desorption of adsorbed hydrogen atoms by recombination. As was distinct from the binary Ni-Mo alloys, after open circuit immersion, the overpotential, that is, the activity of nanocrystalline Ni-Mo-C alloys for hydrogen evolution was not changed, indicating the sufficient durability in the practical electrolysis

  11. Seeding of polymer substrates for nanocrystalline diamond film growth

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Babchenko, Oleg; Kozak, Halyna; Hruška, Karel; Rezek, Bohuslav; Ledinský, Martin; Potměšil, Jiří; Michalka, M.; Vaněček, Milan

    2009-01-01

    Roč. 18, 5-8 (2009), s. 734-739 ISSN 0925-9635 R&D Projects: GA AV ČR KAN400100701; GA AV ČR KAN400100652 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond films * chemical vapor deposition * polymer * sscanning electron spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.822, year: 2009

  12. A study of the structure and crystallisation of nanocrystalline zirconia

    International Nuclear Information System (INIS)

    Tucker, M.

    1999-12-01

    Nanocrystalline zirconia, prepared via, calcination of the hydroxide, has been studied using a variety of experimental techniques. Two chemical routes, a precipitation and a sol-gel route, were used to prepare the hydroxide. Neutron and X-ray diffraction, EXAFS, NMR and SANS have been used to study the structure and crystallisation, during in-situ and ambient condition measurements. The structural information from the diffraction data has been complimented by the other techniques to provide information on the short, medium and longer range structure of nanocrystalline zirconia. Pure and yttrium doped samples were studied, this enabled the affects of doping and preparation routes to be investigated. The amorphous hydroxide was found to have a, monoclinic-like structure for all samples, independent of preparation route or yttrium content. The crystallisation temperature was lowest for the pure precipitation sample and was increased by the addition of yttrium or by preparation via, the sol-gel route. For the precipitation samples, in addition to the crystallisation temperature being raised, doping with yttrium also had an effect on the size of the crystallites obtained at high temperatures. Due to the different incorporation method of the yttrium into the sol-gel samples the effect on crystallite size and crystallisation temperature, as seen for the precipitation samples, were not evident for the sol-gel samples. The neutron and NMR data clearly show hydrogen remains in the samples well after crystallisation has become evident. The structural picture of nanocrystalline zirconia consisting of small crystallites surrounded by material containing, or terminated by, hydroxyl groups, is supported by all the results and methods used in this thesis. The in-situ and ambient conditions data is combined into a coherent growth picture of the nanocrystalline material from the hydroxide until at high enough temperatures the bulk or polycrystalline material is formed. (author)

  13. Transport properties of hydrogen-terminated nanocrystalline diamond films

    Czech Academy of Sciences Publication Activity Database

    Hubík, Pavel; Mareš, Jiří J.; Kozak, Halyna; Kromka, Alexander; Rezek, Bohuslav; Krištofik, Jozef; Kindl, Dobroslav

    2012-01-01

    Roč. 24, April (2012), 63-68 ISSN 0925-9635 R&D Projects: GA AV ČR KAN400100701; GA AV ČR(CZ) IAAX00100902; GA ČR GAP204/10/0212 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond * hydrogen termination * grain boundaries * Hall effect * transport mechanism Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.709, year: 2012

  14. Photoluminescence and infrared absorption spectra of aminated nanocrystalline diamond surface

    Czech Academy of Sciences Publication Activity Database

    Remeš, Zdeněk; Kozak, Halyna; Babchenko, Oleg; Ukraintsev, Egor; Kromka, Alexander

    2013-01-01

    Roč. 5, č. 6 (2013), s. 515-518 ISSN 2164-6627 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GPP205/12/P331; GA MŠk LH12236; GA MŠk LH12186 Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * infrared spectroscopy * photoluminescence * fluorescamine Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

    Czech Academy of Sciences Publication Activity Database

    Remeš, Zdeněk; Sun, S. J.; Varga, M.; Chou, H.; Hsu, H.S.; Kromka, A.; Horák, Pavel

    2015-01-01

    Roč. 394, Nov (2015), s. 477-480 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk(CZ) LD14011 EU Projects: European Commission(XE) COST Action MP1202 HINT Institutional support: RVO:68378271 ; RVO:61389005 Keywords : diamond * nonmetallic ferromagnetic materials * fine-particle systems * nanocrystalline materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.357, year: 2015

  16. Microwave PECVD of nanocrystalline diamond with rf induced bias nucleation

    Czech Academy of Sciences Publication Activity Database

    Frgala, Z.; Jašek, O.; Karásková, M.; Zajíčková, L.; Buršíková, V.; Franta, D.; Matějková, Jiřina; Rek, Antonín; Klapetek, P.; Buršík, Jiří

    2006-01-01

    Roč. 56, Suppl. B (2006), s. 1218-1223 ISSN 0011-4626 R&D Projects: GA ČR(CZ) GA202/05/0607 Institutional research plan: CEZ:AV0Z20650511; CEZ:AV0Z20410507 Keywords : nanocrystalline diamond * plasma enhanced chemical vapor deposition * self- bias Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.568, year: 2006

  17. Zn K-edge XANES in nanocrystalline ZnO

    International Nuclear Information System (INIS)

    Kuzmin, A; Larcheri, S; Rocca, F

    2007-01-01

    Zn K-edge XANES in ZnO has been calculated within the full-multiple-scattering (FMS) and finite difference method (FDM) formalism using the ab initio FDMNES code. The influence of non-muffin-tin potential, bulk defects, surface termination and polarization effects on XANES has been analysed. The obtained theoretical results are compared with available experimental data for polycrystalline and nanocrystalline zinc oxide systems

  18. Zn K-edge XANES in nanocrystalline ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, A [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Larcheri, S [IFN-CNR, Istituto di Fotonica e Nanotecnologie del Consiglio Nazionale delle Ricerche, Sezione di Trento, Povo (Trento) (Italy); Rocca, F [IFN-CNR, Istituto di Fotonica e Nanotecnologie del Consiglio Nazionale delle Ricerche, Sezione di Trento, Povo (Trento) (Italy)

    2007-12-15

    Zn K-edge XANES in ZnO has been calculated within the full-multiple-scattering (FMS) and finite difference method (FDM) formalism using the ab initio FDMNES code. The influence of non-muffin-tin potential, bulk defects, surface termination and polarization effects on XANES has been analysed. The obtained theoretical results are compared with available experimental data for polycrystalline and nanocrystalline zinc oxide systems.

  19. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    Passivation behaviour of nanocrystalline coating (Fe80Si20) obtained by in situ mechanical alloying route is studied and compared with that of the commercial pure iron and cast Fe80Si20 in sodium borate buffer solution at two different pH values (7.7 and 8.4). The coating reveals single passivation at a pH of 7.7 and ...

  20. Thermoelectric nanocrystalline YbCoSb laser prepared layers

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Zeipl, Radek; Kocourek, Tomáš; Remsa, Jan; Navrátil, Jiří

    2016-01-01

    Roč. 122, č. 3 (2016), s. 1-5, č. článku 155. ISSN 0947-8396 R&D Projects: GA ČR(CZ) GA13-33056S Institutional support: RVO:68378271 ; RVO:61389013 Keywords : nanocrystalline YbCoSb * thermoelectric layers * pulsed laser deposition Subject RIV: BM - Solid Matter Physics ; Magnetism; CA - Inorganic Chemistry (UMCH-V) Impact factor: 1.455, year: 2016

  1. Quantum transport in boron-doped nanocrystalline diamond

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří J.; Hubík, Pavel; Krištofik, Jozef; Kindl, Dobroslav; Nesládek, Miloš

    2008-01-01

    Roč. 14, č. 7-8 (2008), s. 161-172 ISSN 0948-1907 R&D Projects: GA ČR GA202/07/0525; GA AV ČR IAA1010404; GA ČR(CZ) GA202/06/0040 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond film * ballistic transport * superconductivity * Josephson’s effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.483, year: 2008

  2. Gas sensing application of nanocrystalline zinc oxide thin films ...

    Indian Academy of Sciences (India)

    Nanocrystalline oxygen-deficient ZnO thinfilm sensors were prepared by spray pyrolysis technique using zinc acetate dissolved in propanol and water as precursor. Response of the sensor to target gases NO2 and H2S is studied. At optimum temperature of 200° C, the sensors have a response of 3.32 to 7 ppm NO2 and 1.4 ...

  3. Uncertainty propagation in a multiscale model of nanocrystalline plasticity

    International Nuclear Information System (INIS)

    Koslowski, M.; Strachan, Alejandro

    2011-01-01

    We characterize how uncertainties propagate across spatial and temporal scales in a physics-based model of nanocrystalline plasticity of fcc metals. Our model combines molecular dynamics (MD) simulations to characterize atomic-level processes that govern dislocation-based-plastic deformation with a phase field approach to dislocation dynamics (PFDD) that describes how an ensemble of dislocations evolve and interact to determine the mechanical response of the material. We apply this approach to a nanocrystalline Ni specimen of interest in micro-electromechanical (MEMS) switches. Our approach enables us to quantify how internal stresses that result from the fabrication process affect the properties of dislocations (using MD) and how these properties, in turn, affect the yield stress of the metallic membrane (using the PFMM model). Our predictions show that, for a nanocrystalline sample with small grain size (4 nm), a variation in residual stress of 20 MPa (typical in today's microfabrication techniques) would result in a variation on the critical resolved shear yield stress of approximately 15 MPa, a very small fraction of the nominal value of approximately 9 GPa. - Highlights: → Quantify how fabrication uncertainties affect yield stress in a microswitch component. → Propagate uncertainties in a multiscale model of single crystal plasticity. → Molecular dynamics quantifies how fabrication variations affect dislocations. → Dislocation dynamics relate variations in dislocation properties to yield stress.

  4. Model for temperature-dependent magnetization of nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Q.; Niewczas, M. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S4M1 (Canada)

    2015-01-07

    A magnetization model of nanocrystalline materials incorporating intragrain anisotropies, intergrain interactions, and texture effects has been extended to include the thermal fluctuations. The method relies on the stochastic Landau–Lifshitz–Gilbert theory of magnetization dynamics and permits to study the magnetic properties of nanocrystalline materials at arbitrary temperature below the Currie temperature. The model has been used to determine the intergrain exchange constant and grain boundary anisotropy constant of nanocrystalline Ni at 100 K and 298 K. It is found that the thermal fluctuations suppress the strength of the intergrain exchange coupling and also reduce the grain boundary anisotropy. In comparison with its value at 2 K, the interparticle exchange constant decreases by 16% and 42% and the grain boundary anisotropy constant decreases by 28% and 40% at 100 K and 298 K, respectively. An application of the model to study the grain size-dependent magnetization indicates that when the thermal activation energy is comparable to the free energy of grains, the decrease in the grain size leads to the decrease in the magnetic permeability and saturation magnetization. The mechanism by which the grain size influences the magnetic properties of nc–Ni is discussed.

  5. XRD and HREM studies of nanocrystalline Cu and Pd

    International Nuclear Information System (INIS)

    Nieman, G.W.; Weertmen, J.R.; Siegel, R.W.

    1991-01-01

    Consolidated powders of nanocrystalline Cu and Pd have been studied by x-ray diffraction (XRD) and high resolution electron microscopy (HREM) as part of an investigation of the mechanical behavior of nanocrystalline pure metals. XRD line broadening measurements were made to estimate rain size, qualitative grain size distribution and average long range strains in a number of samples. Mean grain sized range from 4-60 nm and have qualitatively narrow grain size distributions. Long range lattice strains are of the order of 0.2-3% in consolidated samples. These strains apparently persist and even increase in Cu samples after annealing at 0.35 Tm (498K) for 2h, accompanied by an apparent increase in grain size of ≥2x. Grain size, grain size distribution width and internal strains vary somewhat among samples produced under apparently identical processing conditions. HREM studies show that twins, stacking faults and low-index facets are abundant in as-consolidated nanocrystalline Cu samples. In this paper methodology, results and analysis of XRD and HREM experiments are presented

  6. Neural learning circuits utilizing nano-crystalline silicon transistors and memristors.

    Science.gov (United States)

    Cantley, Kurtis D; Subramaniam, Anand; Stiegler, Harvey J; Chapman, Richard A; Vogel, Eric M

    2012-04-01

    Properties of neural circuits are demonstrated via SPICE simulations and their applications are discussed. The neuron and synapse subcircuits include ambipolar nano-crystalline silicon transistor and memristor device models based on measured data. Neuron circuit characteristics and the Hebbian synaptic learning rule are shown to be similar to biology. Changes in the average firing rate learning rule depending on various circuit parameters are also presented. The subcircuits are then connected into larger neural networks that demonstrate fundamental properties including associative learning and pulse coincidence detection. Learned extraction of a fundamental frequency component from noisy inputs is demonstrated. It is then shown that if the fundamental sinusoid of one neuron input is out of phase with the rest, its synaptic connection changes differently than the others. Such behavior indicates that the system can learn to detect which signals are important in the general population, and that there is a spike-timing-dependent component of the learning mechanism. Finally, future circuit design and considerations are discussed, including requirements for the memristive device.

  7. Ultra-high wear resistance of ultra-nanocrystalline diamond film: Correlation with microstructure and morphology

    Science.gov (United States)

    Rani, R.; Kumar, N.; Lin, I.-Nan

    2016-05-01

    Nanostructured diamond films are having numerous unique properties including superior tribological behavior which is promising for enhancing energy efficiency and life time of the sliding devices. High wear resistance is the principal criterion for the smooth functioning of any sliding device. Such properties are achievable by tailoring the grain size and grain boundary volume fraction in nanodiamond film. Ultra-nanocrystalline diamond (UNCD) film was attainable using optimized gas plasma condition in a microwave plasma enhanced chemical vapor deposition (MPECVD) system. Crystalline phase of ultra-nanodiamond grains with matrix phase of amorphous carbon and short range ordered graphite are encapsulated in nanowire shaped morphology. Film showed ultra-high wear resistance and frictional stability in micro-tribological contact conditions. The negligible wear of film at the beginning of the tribological contact was later transformed into the wearless regime for prolonged sliding cycles. Both surface roughness and high contact stress were the main reasons of wear at the beginning of sliding cycles. However, the interface gets smoothened due to continuous sliding, finally leaded to the wearless regime.

  8. Diodes of nanocrystalline SiC on n-/n+-type epitaxial crystalline 6H-SiC

    Science.gov (United States)

    Zheng, Junding; Wei, Wensheng; Zhang, Chunxi; He, Mingchang; Li, Chang

    2018-03-01

    The diodes of nanocrystalline SiC on epitaxial crystalline (n-/n+)6H-SiC wafers were investigated, where the (n+)6H-SiC layer was treated as cathode. For the first unit, a heavily boron doped SiC film as anode was directly deposited by plasma enhanced chemical vapor deposition method on the wafer. As to the second one, an intrinsic SiC film was fabricated to insert between the wafer and the SiC anode. The third one included the SiC anode, an intrinsic SiC layer and a lightly phosphorus doped SiC film besides the wafer. Nanocrystallization in the yielded films was illustrated by means of X-ray diffraction, transmission electronic microscope and Raman spectrum respectively. Current vs. voltage traces of the obtained devices were checked to show as rectifying behaviors of semiconductor diodes, the conduction mechanisms were studied. Reverse recovery current waveforms were detected to analyze the recovery performance. The nanocrystalline SiC films in base region of the fabricated diodes are demonstrated as local regions for lifetime control of minority carriers to improve the reverse recovery properties.

  9. Comparison of performance of classical clinical chemistry analysers with test-strip devices (Reflotron) and those based on film technology (Vitros) in external quality assessment (EQA) surveys.

    Science.gov (United States)

    Wood, William Graham

    2008-01-01

    This article reports on the performance of two "dry" chemistry devices, (Reflotron, Roche Diagnostics and Vitros, Johnson & Johnson) and compared them with classical "wet" chemistry analysers in four commercially produced quality assessment samples (Roche PNU and PPU and Seronorm Human and Human High Controls) sent repeatedly over a 12-month observation period. Eleven analytes (including five enzymes) were studied, eight of which had target values set by reference method procedures. The results showed that both devices gave comparative results for the same sample sent in different EQA-surveys. Statistically significant differences which occurred were due to the high precision of measurement with a minimal shift in the measured concentrations. They had no clinical relevance in interpretation of results. Comparisons between "dry" and "wet" chemistry results for the same analyte were almost always statistically significantly different and often large enough to influence the clinical interpretation of results. Examples here were glucose and uric acid measured with the Reflotron and compared with other Roche devices (Cobas, Hitachi). The Vitros showed deviant values for urea and creatinine, when compared with other measuring devices using liquid reagents. Differences seen were constant over time, but must be seen in context with the matrices of the samples sent. The results show the long term stability of both reagents and test kits, a necessary prerequisite for long-term controlling of precision and indirectly accuracy of patient measurements.

  10. The effect of post annealing treatment on the citrate sol-gel derived nanocrystalline BaFe12O19 powder: structural, morphological, optical and magnetic properties

    Science.gov (United States)

    Brightlin, B. C.; Balamurugan, S.

    2016-11-01

    The nanocrystalline BaFe12O19 powders were obtained from citrate sol-gel combustion-derived powder upon annealing at 800-1100 °C, and explored their structural, micro-structural, optical and magnetic properties. The thermal decomposition of citrate sol-gel combustion product was verified by means of thermogravimetric and differential thermal analysis. Structural identification of the citrate sol-gel combustion powder and annealed samples were investigated by powder X-ray diffraction. Though the combustion product exhibits cubic spinel phase material, the annealed powder yields good quality nanocrystalline hexagonal BaFe12O19 phase materials. The thin plate-like flakes morphology with random particle sizes of 100-200 nm with slightly agglomerated particles of BaFe12O19 phase is analyzed by high resolution scanning electron microscopy for the good quality annealed sample. Photoluminescence emission spectrum of BaFe12O19 material reveals broad emission peak at 360 nm under the excitation wavelength of 270 nm. Interestingly, the near infrared relative reflectivity of the nanocrystalline BaFe12O19 materials obtained by citrate sol-gel synthesis method is higher than the nanocrystalline BaFe12O19 materials obtained by mechano-thermal and co-precipitation method. The present dark brown colored BaFe12O19 materials can be applied as a ceramic color pigment which includes several applications. The room temperature magnetic hysteresis loop of the annealed BaFe12O19 sample exhibits a ferromagnetic saturation magnetization, M s of 55.774 emu/g at 15 kOe.

  11. The effect of post annealing treatment on the citrate sol–gel derived nanocrystalline BaFe12O19 powder: structural, morphological, optical and magnetic properties

    Directory of Open Access Journals (Sweden)

    B. C. Brightlin

    2016-05-01

    Full Text Available Abstract The nanocrystalline BaFe12O19 powders were obtained from citrate sol–gel combustion-derived powder upon annealing at 800–1100 °C, and explored their structural, micro-structural, optical and magnetic properties. The thermal decomposition of citrate sol–gel combustion product was verified by means of thermogravimetric and differential thermal analysis. Structural identification of the citrate sol–gel combustion powder and annealed samples were investigated by powder X-ray diffraction. Though the combustion product exhibits cubic spinel phase material, the annealed powder yields good quality nanocrystalline hexagonal BaFe12O19 phase materials. The thin plate-like flakes morphology with random particle sizes of ~100–200 nm with slightly agglomerated particles of BaFe12O19 phase is analyzed by high resolution scanning electron microscopy for the good quality annealed sample. Photoluminescence emission spectrum of BaFe12O19 material reveals broad emission peak at ~360 nm under the excitation wavelength of 270 nm. Interestingly, the near infrared relative reflectivity of the nanocrystalline BaFe12O19 materials obtained by citrate sol-gel synthesis method is higher than the nanocrystalline BaFe12O19 materials obtained by mechano-thermal and co-precipitation method. The present dark brown colored BaFe12O19 materials can be applied as a ceramic color pigment which includes several applications. The room temperature magnetic hysteresis loop of the annealed BaFe12O19 sample exhibits a ferromagnetic saturation magnetization, M s of 55.774 emu/g at 15 kOe.

  12. Demonstration of Ultra High-Strength Nanocrystalline Copper Alloys for Military Applications

    Science.gov (United States)

    2012-01-22

    the consolidated samples was determined by using Archimedes principle . Processing diagram 1 shows a general flow process for the steps involved in...Demonstration of Ultrahigh-Strength Nanocrystalline Copper Alloys for Military Applications Project Number: WP-2139 Performing...1-26-2012 Final Dec 2010 - Dec 2011 Demonstration of Ultra High-Strength Nanocrystalline Copper Alloys for Military Applications WP-2139Kris

  13. Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis ...

    Indian Academy of Sciences (India)

    Administrator

    Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis for hydrogen gas detection. LALCHAND A PATIL* .... tions of nanocrystalline TiO2 thin films using spray pyro- lysis. 2.4 Thickness and roughness determination of ... Electrical and gas sensing properties were measured using a static gas sensing system.

  14. Structure and coercivity of nanocrystalline Fe–Si–B–Nb–Cu alloys

    Indian Academy of Sciences (India)

    Unknown

    Fe–Si–B–Nb–Cu alloy; melt-spinning; crystallization; nanocrystalline materials; coercivity. 1. Introduction. Nanocrystalline Fe–Si–B–Nb–Cu alloys have been found to possess a unique combination of soft magnetic properties including high saturation, very low coercivity, high per- meability and high electrical resistivity ...

  15. Accumulation and recovery of defects in ion-irradiated nanocrystalline gold

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Y. E-mail: chimi@popsvr.tokai.jaeri.go.jp; Iwase, A.; Ishikawa, N.; Kobiyama, M.; Inami, T.; Okuda, S

    2001-09-01

    Effects of 60 MeV {sup 12}C ion irradiation on nanocrystalline gold (nano-Au) are studied. The experimental results show that the irradiation-produced defects in nano-Au are thermally unstable because of the existence of a large volume fraction of grain boundaries. This suggests a possibility of the use of nanocrystalline materials as irradiation-resistant materials.

  16. Covalent attachment and growth of nanocrystalline films of photocatalytic TiOF 2

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jian [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China; Lv, Fujian [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China; Xiao, Shengxiong [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China; Bian, Zhenfeng [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China; Buntkowsky, Gerd [Eduard-Zintl-Institut für Anorganische und Physikalische Chemie Technische Universität Darmstadt; , Germany; Nuckolls, Colin [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China; Department of Chemistry; Columbia University; Li, Hexing [Chinese Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials; Shanghai Normal University; Shanghai, China

    2014-01-01

    An evaporation induced alcoholysis process has been applied to synthesize nanocrystalline TiOF2film. The nanocrystalline TiOF2becomes chemically attached to the surface of the glass slide. These films show potential applications in both photocatalytic and antibacterial fields.

  17. Improving Process Quality by Means of Accurate and Traceable Calibration of Flow Devices with Process-oriented Liquids.

    Science.gov (United States)

    Bissig, Hugo; Tschannen, Martin; de Huu, Marc

    2018-03-30

    Calibration of flow devices is important in several areas of pharmaceutical, flow chemistry and health care applications where volumetric dosage or delivery at given flow rates are crucial for the process. Although most of the flow devices are measuring flow rates of process-oriented liquids, their calibrations are often performed with water as calibration liquid. It is recommended to perform the calibrations of the flow devices with process-oriented liquids as the liquid itself might influence the performance of the flow devices. Therefore, METAS has developed facilities with METAS flow generators to address the issue of measuring with process-oriented liquids for flow rates from 400 ml/min down to 50 nl/min with uncertainties from 0.07-0.9 %. Traceability is guaranteed through the calibration of the generated flow rates of the METAS flow generators by means of the dynamic gravimetric method where a liquid of well-known density and a well-controlled evaporation rate is used. The design of the milli-flow facility will be discussed as well as first measurement results of the METAS flow generators in the range of micro-flow and milli-flow using water and other liquids.

  18. An advanced current control compensation scheme to improve the microgrid power quality without using dedicated compensation devices

    DEFF Research Database (Denmark)

    Naderipour, A.; Zin, A. A.Mohd; Habibuddin, M. H.

    2016-01-01

    of the harmonics in Microgrid (MG) and between MG and Power Common Coupling (PCC). The current harmonics in the grid and MG are compensated without using dedicated compensation devices, such as active power filters (APFs), by the proposed current controller which is contain an advanced synchronous reference frame...

  19. Emergency CT brain: preliminary interpretation with a tablet device: image quality and diagnostic performance of the Apple iPad.

    LENUS (Irish Health Repository)

    Mc Laughlin, Patrick

    2012-04-01

    Tablet devices have recently been used in radiological image interpretation because they have a display resolution comparable to desktop LCD monitors. We identified a need to examine tablet display performance prior to their use in preliminary interpretation of radiological images. We compared the spatial and contrast resolution of a commercially available tablet display with a diagnostic grade 2 megapixel monochrome LCD using a contrast detail phantom. We also recorded reporting discrepancies, using the ACR RADPEER system, between preliminary interpretation of 100 emergency CT brain examinations on the tablet display and formal review on a diagnostic LCD. The iPad display performed inferiorly to the diagnostic monochrome display without the ability to zoom. When the software zoom function was enabled on the tablet device, comparable contrast detail phantom scores of 163 vs 165 points were achieved. No reporting discrepancies were encountered during the interpretation of 43 normal examinations and five cases of acute intracranial hemorrhage. There were seven RADPEER2 (understandable) misses when using the iPad display and 12 with the diagnostic LCD. Use of software zoom in the tablet device improved its contrast detail phantom score. The tablet allowed satisfactory identification of acute CT brain findings, but additional research will be required to examine the cause of "understandable" reporting discrepancies that occur when using tablet devices.

  20. In vitro corrosion, cytotoxicity and hemocompatibility of bulk nanocrystalline pure iron

    Energy Technology Data Exchange (ETDEWEB)

    Nie, F L; Zheng, Y F [State Key Laboratory for Turbulence and Complex System, Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Wei, S C [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100083 (China); Hu, C; Yang, G, E-mail: niefeilong@pku.edu.c, E-mail: yfzheng@pku.edu.c, E-mail: weishicheng99@163.co, E-mail: huchao511@gmail.co, E-mail: yanggang@nercast.co [Institute for Structural Materials, Central Iron and Steel Research Institute, Beijing 100081 (China)

    2010-12-15

    Bulk nanocrystalline pure iron rods were fabricated by the equal channel angular pressure (ECAP) technique up to eight passes. The microstructure and grain size distribution, natural immersion and electrochemical corrosion in simulated body fluid, cellular responses and hemocompatibility were investigated in this study. The results indicate that nanocrystalline pure iron after severe plastic deformation (SPD) would sustain durable span duration and exhibit much stronger corrosion resistance than that of the microcrystalline pure iron. The interaction of different cell lines reveals that the nanocrystalline pure iron stimulates better proliferation of fibroblast cells and preferable promotion of endothelialization, while inhibits effectively the viability of vascular smooth muscle cells (VSMCs). The burst of red cells and adhesion of the platelets were also substantially suppressed on contact with the nanocrystalline pure iron in blood circulation. A clear size-dependent behavior from the grain nature deduced by the gradual refinement microstructures was given and well-behaved in vitro biocompatibility of nanocrystalline pure iron was concluded.

  1. How to Assess the Quality of Glucose Clamps? Evaluation of Clamps Performed With ClampArt, a Novel Automated Clamp Device.

    Science.gov (United States)

    Benesch, Carsten; Heise, Tim; Klein, Oliver; Heinemann, Lutz; Arnolds, Sabine

    2015-07-01

    There are no widely accepted parameters to assess the quality of glucose clamps. Thus, we selected different parameters describing clamp quality. These parameters were then evaluated in glucose clamps carried out with ClampArt, a novel CE-marked, state-of-the-art fully automated glucose clamp device employing continuous blood glucose (BG) measurements and minute-by-minute adaptations of glucose infusion rate (GIR). Thirty-nine glucose clamps were performed in 10 healthy and 29 subjects with type 1 diabetes (T1DM) (total duration 583 h). ClampArt-based BG measurements were compared with those obtained with a laboratory reference method. Clamp quality was assessed by 5 parameters: (1) difference (mg/dl) of all paired BG measurements of ClampArt versus reference method ("trueness"), (2) coefficient of variation (CV, %) of ClampArt's BG measurements at target clamp level ("precision"), (3) mean absolute relative difference (MARD, %) at target clamp level ("accuracy"), (4) difference (mg/dl) between ClampArt and target BG ("control deviation"), and (5) percentage operational time ("utility"). ClampArt-based BG measurements showed a trueness of 1.2 ± 2.5 mg/dl. CV and MARD at target BG were 5.5 ± 2.1% and 5.3 ± 2.3%, respectively. There were only small deviations from target level (1.2 ± 1.6 mg/dl). Operational time was as high as 95.4% ± 4.1% (means ± SD). The selected parameters seem to be adequate to characterize clamp quality. The novel, fully automated clamp device ClampArt achieves high clamp quality, which in future trials should be compared with other (automated and manual) clamp methods. © 2015 Diabetes Technology Society.

  2. Organic hybrid planar-nanocrystalline bulk heterojunctions

    Science.gov (United States)

    Forrest, Stephen R [Ann Arbor, MI; Yang, Fan [Piscataway, NJ

    2011-03-01

    A photosensitive optoelectronic device having an improved hybrid planar bulk heterojunction includes a plurality of photoconductive materials disposed between the anode and the cathode. The photoconductive materials include a first continuous layer of donor material and a second continuous layer of acceptor material. A first network of donor material or materials extends from the first continuous layer toward the second continuous layer, providing continuous pathways for conduction of holes to the first continuous layer. A second network of acceptor material or materials extends from the second continuous layer toward the first continuous layer, providing continuous pathways for conduction of electrons to the second continuous layer. The first network and the second network are interlaced with each other. At least one other photoconductive material is interspersed between the interlaced networks. This other photoconductive material or materials has an absorption spectra different from the donor and acceptor materials.

  3. The radiation response of mesoporous nanocrystalline zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Manzini, Ayelén M.; Alurralde, Martin A. [Comisión Nacional de Energía Atómica, Centro Atómico Constituyentes, Av. General Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Giménez, Gustavo [Instituto Nacional de Tecnología Industrial - CMNB, Av. General Paz 5445, 1650 San Martín, Provincia de Buenos Aires (Argentina); Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Comisión Nacional de Energía Atómica, Centro Atómico Constituyentes, Av. General Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina)

    2016-12-15

    The next generation of nuclear systems will require materials capable of withstanding hostile chemical, physical and radiation environments over long time-frames. Aside from its chemical and physical stability, crystalline zirconia is one of the most radiation tolerant materials known. Here we report the first ever study of the radiation response of nanocrystalline and mesoporous zirconia and Ce{sup 3+}-stabilized nanocrystalline zirconia (Ce{sub 0.1}Zr{sub 0.9}O{sub 2}) thin films supported on silicon wafers. Zirconia films prepared using the block copolymer Brij-58 as the template had a thickness of around 60–80 nm. In the absence of a stabilizing trivalent cation they consisted of monoclinic and tetragonal zirconia nanocrystals with diameters in the range 8–10 nm. Films stabilized with Ce{sup 3+} contained only the tetragonal phase. The thin films were irradiated with iodine ions of energies of 70 MeV and 132 keV at low fluences (10{sup 13} - 10{sup 14} cm{sup −2}) corresponding to doses of 0.002 and 1.73 dpa respectively, and at 180 keV and high fluences (2 × 10{sup 16} cm{sup −2}) corresponding to 82.4 dpa. The influence of heavy ion irradiation on the nanocrystalline structure was monitored through Rietveld analysis of grazing incidence X-ray diffraction (GIXRD) patterns recorded at angles close to the critical angle to ensure minimum contribution to the diffraction pattern from the substrate. Irradiation of the mesoporous nanocrystalline zirconia thin films with 70 MeV iodine ions, for which electronic energy loss is dominant, resulted in slight changes in phase composition and virtually no change in crystallographic parameters as determined by Rietveld analysis. Iodine ion bombardment in the nuclear energy loss regime (132–180 keV) at low fluences did not provoke significant changes in phase composition or crystallographic parameters. However, at 180 keV and high fluences the monoclinic phase was totally eliminated from the GIXRD

  4. The vapor pressure over nano-crystalline ice

    Directory of Open Access Journals (Sweden)

    M. Nachbar

    2018-03-01

    Full Text Available The crystallization of amorphous solid water (ASW is known to form nano-crystalline ice. The influence of the nanoscale crystallite size on physical properties like the vapor pressure is relevant for processes in which the crystallization of amorphous ices occurs, e.g., in interstellar ices or cold ice cloud formation in planetary atmospheres, but up to now is not well understood. Here, we present laboratory measurements on the saturation vapor pressure over ice crystallized from ASW between 135 and 190 K. Below 160 K, where the crystallization of ASW is known to form nano-crystalline ice, we obtain a saturation vapor pressure that is 100 to 200 % higher compared to stable hexagonal ice. This elevated vapor pressure is in striking contrast to the vapor pressure of stacking disordered ice which is expected to be the prevailing ice polymorph at these temperatures with a vapor pressure at most 18 % higher than that of hexagonal ice. This apparent discrepancy can be reconciled by assuming that nanoscale crystallites form in the crystallization process of ASW. The high curvature of the nano-crystallites results in a vapor pressure increase that can be described by the Kelvin equation. Our measurements are consistent with the assumption that ASW is the first solid form of ice deposited from the vapor phase at temperatures up to 160 K. Nano-crystalline ice with a mean diameter between 7 and 19 nm forms thereafter by crystallization within the ASW matrix. The estimated crystal sizes are in agreement with reported crystal size measurements and remain stable for hours below 160 K. Thus, this ice polymorph may be regarded as an independent phase for many atmospheric processes below 160 K and we parameterize its vapor pressure using a constant Gibbs free energy difference of 982  ±  182 J mol−1 relative to hexagonal ice.

  5. Preliminary functional results and quality of life after implantation of a new bone conduction hearing device in patients with conductive and mixed hearing loss.

    Science.gov (United States)

    Ihler, Friedrich; Volbers, Laura; Blum, Jenny; Matthias, Christoph; Canis, Martin

    2014-02-01

    To review functional results and quality of life of the first patients implanted with a newly introduced bone conduction implant system. Retrospective chart analysis of 6 patients (6 ears) implanted for conductive hearing loss (CHL) and mixed hearing loss (MHL) in 1 tertiary referral center between July 2012 and February 2013. Implantation of a new bone conduction hearing device. Pure tone audiometry (air conduction and bone conduction thresholds, pure tone average, air-bone gap, and functional gain), speech audiometry (Freiburg Monosyllabic Test), intraoperative and postoperative complication rate, and patient satisfaction (Glasgow benefit inventory [GBI]) were assessed. Air-conduction pure tone average (PTA) was 58.8 ± 8.2 dB HL. Unaided average air-bone gap (ABG) was 33.3 ± 6.2 dB. Aided air-conduction PTA in sound field was 25.2 ± 5.1 dB HL. Aided average ABG was -0.3 ± 7.3 dB. Average functional gain was 33.6 ± 7.2 dB. Mean improvement of GBI was +36.1. No intraoperative complications occurred. During a follow-up period of 8.5 ± 2.2 months, no device failure and no need for revision surgery occurred. Audiometric results of the new bone conduction hearing system are satisfying and comparable to the results of devices that have been applied previously for CHL and MHL. Intraoperatively and postoperatively, no complications were noted.

  6. Inversion degree and saturation magnetization of different nanocrystalline cobalt ferrites

    International Nuclear Information System (INIS)

    Concas, G.; Spano, G.; Cannas, C.; Musinu, A.; Peddis, D.; Piccaluga, G.

    2009-01-01

    The inversion degree of a series of nanocrystalline samples of CoFe 2 O 4 ferrites has been evaluated by a combined study, which exploits the saturation magnetization at 4.2 K and 57 Fe Moessbauer spectroscopy. The samples, prepared by sol-gel autocombustion, have different thermal history and particle size. The differences observed in the saturation magnetization of these samples are explained in terms of different inversion degrees, as confirmed by the analysis of the components in the Moessbauer spectra. It is notable that the inversion degrees of the samples investigated are set among the highest values reported in the literature.

  7. Directly grown nanocrystalline diamond field-effect transistor microstructures

    Czech Academy of Sciences Publication Activity Database

    Kozak, Halyna; Kromka, Alexander; Babchenko, Oleg; Rezek, Bohuslav

    2010-01-01

    Roč. 8, č. 3 (2010), s. 482-487 ISSN 1546-198X R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510; GA AV ČR(CZ) IAAX00100902; GA AV ČR KAN400100652 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond * microstructures * atomic force microscopy * surface conductivity * field-effect transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.602, year: 2010

  8. How nanocrystalline diamond films become charged in nanoscale

    Czech Academy of Sciences Publication Activity Database

    Verveniotis, Elisseos; Kromka, Alexander; Ledinský, Martin; Rezek, Bohuslav

    2012-01-01

    Roč. 24, č. 4 (2012), s. 39-43 ISSN 0925-9635 R&D Projects: GA ČR GD202/09/H041; GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510; GA ČR GAP204/10/0212 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond * local electrostatic charging * nanoparticle assembly * CS-AFM * KFM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.709, year: 2012

  9. Nanocrystalline CdTe thin films by electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ramesh S. Kapadnis

    2013-03-01

    Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

  10. Mueller matrix spectroscopic ellipsometry study of chiral nanocrystalline cellulose films

    Science.gov (United States)

    Mendoza-Galván, Arturo; Muñoz-Pineda, Eloy; Ribeiro, Sidney J. L.; Santos, Moliria V.; Järrendahl, Kenneth; Arwin, Hans

    2018-02-01

    Chiral nanocrystalline cellulose (NCC) free-standing films were prepared through slow evaporation of aqueous suspensions of cellulose nanocrystals in a nematic chiral liquid crystal phase. Mueller matrix (MM) spectroscopic ellipsometry is used to study the polarization and depolarization properties of the chiral films. In the reflection mode, the MM is similar to the matrices reported for the cuticle of some beetles reflecting near circular left-handed polarized light in the visible range. The polarization properties of light transmitted at normal incidence for different polarization states of incident light are discussed. By using a differential decomposition of the MM, the structural circular birefringence and dichroism of a NCC chiral film are evaluated.

  11. Tailoring the wettability of nanocrystalline TiO 2 films

    Science.gov (United States)

    Liang, Qiyu; Chen, Yan; Fan, Yuzun; Hu, Yong; Wu, Yuedong; Zhao, Ziqiang; Meng, Qingbo

    2012-01-01

    The water contact angle (WCA) of nanocrystalline TiO2 films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ∼156°, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ∼0°. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic-hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

  12. Elemental separation in nanocrystalline Cu-Al alloys

    Science.gov (United States)

    Wang, Y. B.; Liao, X. Z.; Zhao, Y. H.; Cooley, J. C.; Horita, Z.; Zhu, Y. T.

    2013-06-01

    Nanocrystallization by high-energy severe plastic deformation has been reported to increase the solubility of alloy systems and even to mix immiscible elements to form non-equilibrium solid solutions. In this letter, we report an opposite phenomenon—nanocrystallization of a Cu-Al single-phase solid solution by high-pressure torsion separated Al from the Cu matrix when the grain sizes are refined to tens of nanometers. The Al phase was found to form at the grain boundaries of nanocrystalline Cu. The level of the separation increases with decreasing grain size, which suggests that the elemental separation was caused by the grain size effect.

  13. Electron holography of Fe-based nanocrystalline magnetic materials (invited)

    International Nuclear Information System (INIS)

    Shindo, Daisuke; Park, Young-Gil; Gao, Youhui; Park, Hyun Soon

    2004-01-01

    Magnetic domain structures of nanocrystalline magnetic materials were extensively investigated by electron holography with a change in temperature or magnetic field applied. In both soft and hard magnetic materials, the distribution of lines of magnetic flux clarified in situ by electron holography was found to correspond well to their magnetic properties. An attempt to produce a strong magnetic field using a sharp needle made of a permanent magnet, whose movement is controlled by piezo drives has been presented. This article demonstrates that the attempt is promising to investigate the magnetization process of hard magnetic materials by electron holography

  14. SU-F-T-282: Quality Assurance for IMRT/VMAT QA Devices: Issues Affecting the Timing for ArcCHECK Recalibration

    Energy Technology Data Exchange (ETDEWEB)

    Steers, J [Cedars Sinai Medical Center, Los Angeles, CA (United States); University of California-Los Angeles, Los Angeles, CA (United States); Fraass, B [Cedars Sinai Medical Center, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To discuss several factors surrounding the decision on when to recalibrate the ArcCHECK device as well as present a simple and efficient monthly check to evaluate ArcCHECK calibrations. Methods: ArcCheck (Sun Nuclear) calibrations were evaluated monthly by measuring a 25×25cm{sup 2} field with 100 MU. Since ArcCHECK measurements are run on an almost nightly basis, such additional square field measurements are obtained with minimal additional effort. An in-house MATLAB script compares two radial (y-direction) profiles from the top/center of the new measurement relative to a baseline measurement acquired at the last device calibration. The program automatically generates PDF profile and percent difference comparisons for inspection. Recalibration is based on inspection of measurement profile shapes and percent differences from the baseline measurement. Results: The method presented here shows the utility of a simple monthly check for evaluating ArcCHECK calibrations, and in addition shows the importance of recalibrating after Linac beam steering. Our device required recalibration approximately every 8–10 months. However, for ease of scheduling, we propose a bi-annual recalibration interval. Clinics with a lighter/heavier IMRT/VMAT QA case load may require different recalibration intervals, which are easily determined using the single-field method presented. Analysis of additional square fields is also easily incorporated, if desired. We further illustrate the importance of array recalibration given that diode irradiation is not uniform over the entire device, with central diodes receiving more than 900 Gy over the course of 10 months and peripheral diodes receiving as little as 50 Gy (in our experience). Finally, we show that timely device recalibration decreases spread in clinical IMRT/VMAT QA gamma passing rates. Conclusion: Quality assurance for ArcCHECK array calibrations is important to ensure quality IMRT/VMAT QA comparisons. For many clinics

  15. Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices

    Science.gov (United States)

    Bera, Susnata; Singh, Shashi B.; Ray, S. K.

    2012-05-01

    Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage (˜2.2 V) .The EL peak intensity was found to increase by increasing the operating current.

  16. Frequency of Poor Outcome (Death or Poor Quality of Life) After Left Ventricular Assist Device for Destination Therapy: Results From the INTERMACS Registry.

    Science.gov (United States)

    Arnold, Suzanne V; Jones, Philip G; Allen, Larry A; Cohen, David J; Fendler, Timothy J; Holtz, Jonathan E; Aggarwal, Sanjeev; Spertus, John A

    2016-08-01

    A left ventricular assist device (LVAD) improves survival and quality of life for many, but not all, patients with end-stage heart failure who are ineligible for transplantation. We sought to evaluate the frequency of poor outcomes using a novel composite measure that integrates quality of life with mortality. Within the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) national registry, poor outcome was defined as death or an average Kansas City Cardiomyopathy Questionnaire life). Among 1638 patients with LVAD, 29.7% had a poor outcome, with death in 22.4% and persistently poor quality of life in 7.3%. Patients who had a poor outcome were more likely to have higher body mass indices (29.3 versus 28.2 kg/m(2); P=0.007), lower hemoglobin levels (11.1 versus 11.4 g/dL; P=0.005), previous cardiac surgery (47.8% versus 39.8%; P=0.004), history of cancer (13.8% versus 9.7%; P=0.025), severe diabetes mellitus (15.6% versus 11.5%; P=0.038), and poorer quality of life preimplant (Kansas City Cardiomyopathy Questionnaire scores: 29.8 versus 35.3; Plife during the year after LVAD. We identified several factors associated with a poor outcome, which may inform discussions before LVAD implantation to enable more realistic expectations of recovery. © 2016 American Heart Association, Inc.

  17. Amphoteric CdSe nanocrystalline quantum dots.

    Science.gov (United States)

    Islam, Mohammad A

    2008-06-25

    The nanocrystal quantum dot (NQD) charge states strongly influence their electrical transport properties in photovoltaic and electroluminescent devices, optical gains in NQD lasers, and the stability of the dots in thin films. We report a unique electrostatic nature of CdSe NQDs, studied by electrophoretic methods. When we submerged a pair of metal electrodes, in a parallel plate capacitor configuration, into a dilute solution of CdSe NQDs in hexane, and applied a DC voltage across the pair, thin films of CdSe NQDs were deposited on both the positive and the negative electrodes. Extensive characterizations including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman studies revealed that the films on both the positive and the negative electrodes were identical in every respect, clearly indicating that: (1) a fraction (<1%) of the CdSe NQDs in free form in hexane solution are charged and, more importantly, (2) there are equal numbers of positive and negative CdSe NQDs in the hexane solution. Experiments also show that the number of deposited dots is at least an order of magnitude higher than the number of initially charged dots, indicating regeneration. We used simple thermodynamics to explain such amphoteric nature and the charging/regeneration of the CdSe NQDs.

  18. Quality-of-life outcomes after bone-anchored hearing device surgery in children with single-sided sensorineural deafness.

    Science.gov (United States)

    Doshi, Jayesh; Banga, Rupan; Child, Anne; Lawrence, Rebecca; Reid, Andrew; Proops, David; McDermott, Ann-Louise

    2013-01-01

    To report our experience in a series of children with single-sided sensorineural deafness where a bone-anchored hearing device (BAHD) was used for auditory rehabilitation. Retrospective case review. Tertiary referral centre. Eight children (4 boys and 4 girls) who had BAHD surgery for single-sided sensorineural deafness between 2007 and 2010. Bone-anchored hearing device was used for auditory rehabilitation. Glasgow Children's Benefit Inventory (GCBI), Single-sided Deafness (SSD) Questionnaire and change in health benefit scores (visual analogue scale). All but one of the children showed a positive GCBI score; the child that reported a negative score was because of low self confidence and self-esteem issues secondary to bullying at school. The results of the SSD questionnaire were generally positive with a mean satisfaction score of the BAHD as 9/10. All the children had an improvement in heath benefit. Our findings add further evidence to support patient perceived benefit of a BAHD in single sided sensorineural deafness in the paediatric population.

  19. Quality

    International Nuclear Information System (INIS)

    Burnett, N.; Jeffries, J.; Mach, J.; Robson, M.; Pajot, D.; Harrigan, J.; Lebsack, T.; Mullen, D.; Rat, F.; Theys, P.

    1993-01-01

    What is quality? How do you achieve it? How do you keep it once you have got it. The answer for industry at large is the three-step hierarchy of quality control, quality assurance and Total quality Management. An overview is given of the history of quality movement, illustrated with examples from Schlumberger operations, as well as the oil industry's approach to quality. An introduction of the Schlumberger's quality-associated ClientLink program is presented. 15 figs., 4 ills., 16 refs

  20. Investigation of the agglomeration and amorphous transformation effects of neutron irradiation on the nanocrystalline silicon carbide (3C-SiC) using TEM and SEM methods

    Energy Technology Data Exchange (ETDEWEB)

    Huseynov, Elchin M., E-mail: elchin.h@yahoo.com [Department of Nanotechnology and Radiation Material Science, National Nuclear Research Center, Inshaatchilar pr. 4, AZ 1073 Baku (Azerbaijan); Institute of Radiation Problems of Azerbaijan National Academy of Sciences, B.Vahabzade 9, AZ 1143 Baku (Azerbaijan)

    2017-04-01

    Nanocrystalline 3C-SiC particles irradiated by neutron flux during 20 h in TRIGA Mark II light water pool type research reactor. Silicon carbide nanoparticles were analyzed by Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) devices before and after neutron irradiation. The agglomeration of nanoparticles was studied comparatively before and after neutron irradiation. After neutron irradiation the amorphous layer surrounding the nanoparticles was analyzed in TEM device. Neutron irradiation defects in the 3C-SiC nanoparticles and other effects investigated by TEM device. The effect of irradiation on the crystal structure of the nanomaterial was studied by selected area electron diffraction (SAED) and electron diffraction patterns (EDP) analysis.

  1. Intrauterine Devices

    Science.gov (United States)

    S HARE W ITH W OMEN INTRAUTERINE DEVICES INTRAUTERINE DEVICES What is An Intrauterine Device? An intrauterine device (IUD) is anything that is placed inside the uterus (womb) to prevent pregnancy. ...

  2. Chemical Vapor Synthesis of Nanocrystalline Oxides

    Science.gov (United States)

    Djenadic, Ruzica; Winterer, Markus

    The generation of nanoparticles in the gas phase by Chemical Vapor Synthesis (CVS) may be described from the point of view of chemical engineering as a sequence of unit operations among which reactant delivery, reaction energy input, and product separation are key processes which determine the product characteristics and quality required by the applications of nanoparticles and powders. In case of CVS, the volatility of the reactants (precursors) may severely limit the possible type of products as well as the production rate. It is shown that these limits can be lifted by use of a laser flash evaporator which also enables the use of precursor mixtures for the production of complex oxides as shown for Co-doped ZnO and the pulsed operation to influence powder characteristics. The mode in which energy is supplied to the particle synthesis reactor has also substantial influence on particle and powder characteristics as is shown for TiO2 using different time-temperatureprofiles.

  3. EPR Spectroscopy of Different Sol Concentration Synthesized Nanocrystalline-ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Manju Arora

    2015-01-01

    Full Text Available Nanocrystalline zinc oxide (nc-ZnO thin films were grown on p-type silicon substrate through spin coating by sol-gel process using different sol concentrations (10 wt.%, 15 wt.%, and 25 wt.%. These films were characterized by high resolution nondestructive X-ray diffraction (XRD, scanning electron microscopy (SEM with energy dispersive X-ray analysis (EDS attachment, and electron paramagnetic resonance (EPR techniques to understand variations in structural, morphological, and oxygen vacancy with respect to sol concentration. The film surface morphology changes from nanowall to nanorods on increasing sol concentration. EPR spectra revealed the systematic variation from ferromagnetic to paramagnetic nature in these nc-ZnO films. The broad EPR resonance signal arising from the strong dipolar-dipolar interactions among impurity defects present in nc-ZnO film deposited from 10 wt.% sol has been observed and a single strong narrow resonance signal pertaining to oxygen vacancies is obtained in 25 wt.% sol derived nc-ZnO film. The concentrations of impurity defects and oxygen vacancies are evaluated from EPR spectra, necessary for efficient optoelectronic devices development.

  4. Boron-doped nanocrystalline diamond microelectrode arrays monitor cardiac action potentials.

    Science.gov (United States)

    Maybeck, Vanessa; Edgington, Robert; Bongrain, Alexandre; Welch, Joseph O; Scorsone, Emanuel; Bergonzo, Philippe; Jackman, Richard B; Offenhäusser, Andreas

    2014-02-01

    The expansion of diamond-based electronics in the area of biological interfacing has not been as thoroughly explored as applications in electrochemical sensing. However, the biocompatibility of diamond, large safe electrochemical window, stability, and tunable electronic properties provide opportunities to develop new devices for interfacing with electrogenic cells. Here, the fabrication of microelectrode arrays (MEAs) with boron-doped nanocrystalline diamond (BNCD) electrodes and their interfacing with cardiomyocyte-like HL-1 cells to detect cardiac action potentials are presented. A nonreductive means of structuring doped and undoped diamond on the same substrate is shown. The resulting BNCD electrodes show high stability under mechanical stress generated by the cells. It is shown that by fabricating the entire surface of the MEA with NCD, in patterns of conductive doped, and isolating undoped regions, signal detection may be improved up to four-fold over BNCD electrodes passivated with traditional isolators. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Hydrogenated Nanocrystalline Silicon Thin Films Prepared by Hot-Wire Method with Varied Process Pressure

    Directory of Open Access Journals (Sweden)

    V. S. Waman

    2011-01-01

    Full Text Available Hydrogenated nanocrystalline silicon films were prepared by hot-wire method at low substrate temperature (200∘C without hydrogen dilution of silane (SiH4. A variety of techniques, including Raman spectroscopy, low angle X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy, atomic force microscopy (AFM, and UV-visible (UV-Vis spectroscopy, were used to characterize these films for structural and optical properties. Films are grown at reasonably high deposition rates (>15 Å/s, which are very much appreciated for the fabrication of cost effective devices. Different crystalline fractions (from 2.5% to 63% and crystallite size (3.6–6.0 nm can be achieved by controlling the process pressure. It is observed that with increase in process pressure, the hydrogen bonding in the films shifts from Si–H to Si–H2 and (Si–H2n complexes. The band gaps of the films are found in the range 1.83–2.11 eV, whereas the hydrogen content remains <9 at.% over the entire range of process pressure studied. The ease of depositing films with tunable band gap is useful for fabrication of tandem solar cells. A correlation between structural and optical properties has been found and discussed in detail.

  6. Rapid room-temperature synthesis of nanocrystalline spinels as oxygen reduction and evolution electrocatalysts

    Science.gov (United States)

    Cheng, Fangyi; Shen, Jian; Peng, Bo; Pan, Yuede; Tao, Zhanliang; Chen, Jun

    2011-01-01

    Spinels can serve as alternative low-cost bifunctional electrocatalysts for oxygen reduction/evolution reactions (ORR/OER), which are the key barriers in various electrochemical devices such as metal-air batteries, fuel cells and electrolysers. However, conventional ceramic synthesis of crystalline spinels requires an elevated temperature, complicated procedures and prolonged heating time, and the resulting product exhibits limited electrocatalytic performance. It has been challenging to develop energy-saving, facile and rapid synthetic methodologies for highly active spinels. In this Article, we report the synthesis of nanocrystalline MxMn3-xO4 (M = divalent metals) spinels under ambient conditions and their electrocatalytic application. We show rapid and selective formation of tetragonal or cubic MxMn3-xO4 from the reduction of amorphous MnO2 in aqueous M2+ solution. The prepared CoxMn3-xO4 nanoparticles manifest considerable catalytic activity towards the ORR/OER as a result of their high surface areas and abundant defects. The newly discovered phase-dependent electrocatalytic ORR/OER characteristics of Co-Mn-O spinels are also interpreted by experiment and first-principle theoretical studies.

  7. Microstructural and photoluminescence characterisation of germanium and silicon-germanium nanocrystalline materials

    CERN Document Server

    Kartopu, G

    2003-01-01

    The discovery of the strong room temperature visible photoluminescence (PL) emission from porous Si in 1990 has been the catalyst for much of the recent study on the visible PL emitting semiconductor nanocrystalline materials. Silicon, an indirect bandgap semiconductor, in the form of nanoparticles is thought to emit strong visible light due to quantum confinement effects and, in the near future, will replace GaAs (and the other direct bandgap III-IV semiconductors) as for the light emitting devices such as lasers. On the other hand, mainly due to its much larger exciton Bohr radius, Ge, in the form of nanocrystals, is expected show more pronounced quantum confinement effects compared to Si nanocrystals. SiGe alloys also constitute a more attractive material than Si in terms of both industrial applications and fundamental research: the lifetime of the 'porous Si-like' PL of porous SiGe is observed to be approximately two orders of magnitude faster than that of porous Si. Moreover, the bandgap of Si-Ge alloys ...

  8. Magnetic properties of nanocrystalline pyrrhotite prepared by high-energy milling

    DEFF Research Database (Denmark)

    Balaz, P.; Godocikova, E.; Alacova, A.

    2004-01-01

    The nanocrystalline pyrrhotite was prepared by high-energy milling of lead sulphide with elemental Fe acting as reducing element. X-ray diffractometry, Mossbauer spectroscopy and VSM magnetometry were used to determine the properties of nanocrystalline iron sulphide prepared by the corresponding...... mechanochemical reaction. Pyrrhotite Fe1-xS together with the residual Fe metal were identified by the X-ray diffractometry. The kinetic studies performed by Mossbauer spectroscopy and VSM magnetometry allowed us to follow in more details the progress of the nanocrystalline magnetic phase formation during...

  9. Metal contacts in nanocrystalline n-type GaN: Schottky diodes.

    Science.gov (United States)

    Das, S N; Sarangi, S; Sahu, S N; Pal, A K

    2009-04-01

    Contact properties in nanocrystalline n-GaN in thin film form were studied by depositing nanocrystalline films onto aluminium coated fused silica substrates by high pressure sputtering of Si (1 at%) doped GaN target. Schottky diodes were realized with Au, Ni and Pd as top contacts on the nanocrystalline n-GaN films to examine the contact properties of the diodes thus formed. Variation of current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the Schottky diodes were recorded at different temperatures and analyzed in the light of the existing theories.

  10. In situ neutron-diffraction study of tensile deformation of a bulk nanocrystalline alloy

    International Nuclear Information System (INIS)

    Fan, G.J.; Li, L.; Yang, Bin; Choo, H.; Liaw, P.K.; Saleh, T.A.; Clausen, B.; Brown, D.W.

    2009-01-01

    In situ neutron-diffraction technique has been employed to study the uniaxial tensile deformation of a bulk nanocrystalline Ni-Fe alloy. In contrast to an increase in the full-width half-maximum (FWHM) of the neutron-diffraction patterns for the coarse-grained Ni, the FWHM for the nanocrystalline Ni-Fe alloy decreases with increasing the plastic strain, ε P . The deformation with ε P < 1.5% did not introduce a residual lattice strain and a texture in the nanocrystalline Ni-Fe alloy, which were otherwise developed in the coarse-grained Ni

  11. Flame synthesis and characterization of nanocrystalline titania powders

    Directory of Open Access Journals (Sweden)

    Bhaskaran Manjith Kumar

    2012-09-01

    Full Text Available Flame reactors are considered to be one of the most promising and versatile synthesis routes for the largescale production of submicron and nanosized particles. An annular co-flow type oxy-gas diffusion burner was designed for its application in a modular flame reactor for the synthesis of nanocrystalline oxide ceramics. The burner consisted of multiple ports for the individually regulated flow of a precursor vapour, inert gas, fuel gas and oxidizer. The nanopowders formed during flame synthesis in the reaction chamber were collected by a suitable set of filters. In the present study, TTIP was used as the precursor for the synthesis of nanocrystalline TiO2 and helium was used to carry the precursor vapour to the burner head. Methane and oxygen were used as fuel and oxidizer respectively. The operating conditions were varied by systematically changing the flow rates of the gases involved. The synthesized powders were characterized using standard techniques such as XRD, SEM, TEM, BET etc., in order to determine the crystallite size, phase content, morphology, particle size and degree of agglomeration. The influences of gas flow rates on the powder characteristics are discussed.

  12. Amoxicillin photodegradation by nanocrystalline TiO2

    Directory of Open Access Journals (Sweden)

    Radosavljević K D.

    2017-01-01

    Full Text Available Nanocrystalline TiO2, synthesized by sol-gel route and characterized by XRPD, BET and SEM measurements, was applied in the photocatalytic degradation of amoxicillin, using an Osram Ultra-Vitalux® lamp as the light source. Amoxicillin is a semi-synthetic penicillin type antibiotic active against a wide range of grampositive and a limited range of gram-negative organisms. The continuous release of antibiotics and their persistence in the environment may result in serious irreversible effects on aquatic and terrestrial organisms. Heterogeneous catalysis, which uses catalysts like TiO2, is a promising route for the degradation of organic pollutants including antibiotics. The effects of initial concentration of catalyst, initial salt concentration (NaCl and Na2SO4, ethanol and pH on the photocatalytic degradation of amoxicillin were studied. The mineralization of amoxicillin was analyzed by ion chromatography as well as by total organic analysis. The catalytic properties of nanocrystalline TiO2 were compared to Evonik P25 catalyst.

  13. Investigation of nanocrystalline Gd films loaded with hydrogen

    KAUST Repository

    Hruška, Petr

    2015-01-01

    The present work reports on microstructure studies of hydrogen-loaded nanocrystalline Gd films prepared by cold cathode beam sputtering on sapphire (112¯0) substrates. The Gd films were electrochemically step-by-step charged with hydrogen and the structural development with increasing concentration of absorbed hydrogen was studied by transmission electron microscopy and in-situ   X-ray diffraction using synchrotron radiation. The relaxation of hydrogen-induced stresses was examined by acoustic emission measurements. In the low concentration range absorbed hydrogen occupies preferentially vacancy-like defects at GBs typical for nanocrystalline films. With increasing hydrogen concentration hydrogen starts to occupy interstitial sites. At the solid solution limit the grains gradually transform into the ββ-phase (GdH2). Finally at high hydrogen concentrations xH>2.0xH>2.0 H/Gd, the film structure becomes almost completely amorphous. Contrary to bulk Gd specimens, the formation of the γγ-phase (GdH3) was not observed in this work.

  14. Investigation of low temperature thermal stability in bulk nanocrystalline Ni

    International Nuclear Information System (INIS)

    Chauhan, Manish; Mohamed, Farghalli A.

    2006-01-01

    Grain growth behavior of bulk nanocrystalline Ni, prepared by an electrodeposition technique with average grain sizes of 20 and 15nm was investigated in the homologous temperature (T/T m ) range of 0.20-0.40. In studying grain growth, the techniques of X-ray diffraction and transmission electron microscopy were used. The results show that in the temperature range of 0.20-0.30T m , there is no appreciable grain growth, even after long annealing times. However, in the temperature range of 0.3-0.4T m , the rate of grain growth was rapid during the initial period of annealing, which decreases with increase in time. The value of time exponent, n, deduced from the grain growth equation of the general form D 1/n -D 0 1/n =Kt was found to be approximately 0.1 for both grain sizes of Ni. At temperatures higher than 0.3T m , an approximate activation energy of 105+/-3kJ/mol, which is close to the activation energy for grain boundary diffusion in polycrystalline Ni, was measured. At temperatures lower than 0.3T m , an approximate activation energy of 11+/-3kJ/mol was found. It is suggested that this low activation energy represents the energy for the re-ordering of the nanocrystalline grain boundaries

  15. Nanocrystalline functional materials and nanocomposites synthesis through aerosol routes

    Directory of Open Access Journals (Sweden)

    Milošević Olivera B.

    2003-01-01

    Full Text Available This paper represents the results of the design of functional nanocrystalline powders and nanocomposites using chemical reactions in aerosols. The process involves ultrasonic aerosol formation (mist generators with the resonant frequencies of 800 kHz, 1.7 and 2.5 MHz from precursor salt solutions and control over the aerosol decomposition in a high-temperature tubular flow reactor. During decomposition, the aerosol droplets undergo evaporation/drying, precipitation and thermolysis in a single-step process. Consequently, spherical, solid, agglomerate-free submicronic particles are obtained. The particle morphology, revealed as a composite structure consisting of primary crystallites smaller than 20 nm was analysed by several methods (XRD, DSC/DTA, SEM, TEM and discussed in terms of precursor chemistry and process parameters. Following the initial attempts, a more detailed aspect of nanocrystalline particle synthesis was demonstrated for the case of nanocomposites based on ZnO-MeO (MeO=Bi Cr+, suitable for electronic applications, as well as an yttrium-aluminum base complex system, suitable for phosphorus applications. The results imply that parts of the material structure responsible for different functional behaviour appear through in situ aerosol synthesis by processes of intraparticle agglomeration, reaction and sintering in the last synthesis stage.

  16. Magnetotransport in nanocrystalline SmB6 thin films

    Directory of Open Access Journals (Sweden)

    Jie Yong

    2015-07-01

    Full Text Available SmB6 has been predicted to be a prototype of topological Kondo insulator (TKI but its direct experimental evidence as a TKI is still lacking to date. Here we report on our search for the signature of a topological surface state and investigation of the effect of disorder on transport properties in nanocrystalline SmB6 thin films through longitudinal magnetoresistance and Hall coefficient measurements. The magnetoresistance (MR at 2 K is positive and linear (LPMR at low field and become negative and quadratic at higher field. While the negative part is understood from the reduction of the hybridization gap due to Zeeman splitting, the positive dependence is similar to what is observed in other topological insulators (TI. We conclude that the LPMR is a characteristic of TI and is related to the linear dispersion near the Dirac cone. The Hall resistance shows a sign change around 50K. It peaks and becomes nonlinear around 10 K then decreases below 10 K. This indicates that carriers with opposite signs emerge below 50 K. These properties indicate that the surface states are robust and probably topological in our nanocrystalline films.

  17. New atom probe approaches to studying segregation in nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Cao, Y.; Liao, X.Z. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); Cairney, J.M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

    2013-09-15

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess.

  18. New atom probe approaches to studying segregation in nanocrystalline materials

    International Nuclear Information System (INIS)

    Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J.; Cao, Y.; Liao, X.Z.; Cairney, J.M.

    2013-01-01

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess

  19. New atom probe approaches to studying segregation in nanocrystalline materials.

    Science.gov (United States)

    Samudrala, S K; Felfer, P J; Araullo-Peters, V J; Cao, Y; Liao, X Z; Cairney, J M

    2013-09-01

    Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. A variational multiscale constitutive model for nanocrystalline materials

    KAUST Repository

    Gurses, Ercan

    2011-03-01

    This paper presents a variational multi-scale constitutive model in the finite deformation regime capable of capturing the mechanical behavior of nanocrystalline (nc) fcc metals. The nc-material is modeled as a two-phase material consisting of a grain interior phase and a grain boundary effected zone (GBAZ). A rate-independent isotropic porous plasticity model is employed to describe the GBAZ, whereas a crystal-plasticity model which accounts for the transition from partial dislocation to full dislocation mediated plasticity is employed for the grain interior. The constitutive models of both phases are formulated in a small strain framework and extended to finite deformation by use of logarithmic and exponential mappings. Assuming the rule of mixtures, the overall behavior of a given grain is obtained via volume averaging. The scale transition from a single grain to a polycrystal is achieved by Taylor-type homogenization where a log-normal grain size distribution is assumed. It is shown that the proposed model is able to capture the inverse HallPetch effect, i.e., loss of strength with grain size refinement. Finally, the predictive capability of the model is validated against experimental results on nanocrystalline copper and nickel. © 2010 Elsevier Ltd. All rights reserved.

  1. Effect of surface energy on dispersion and mechanical properties of polymer/nanocrystalline cellulose nanocomposites.

    Science.gov (United States)

    Khoshkava, V; Kamal, M R

    2013-09-09

    Dispersion quality and polymer-filler interaction are important factors in determining the final properties of polymer nanocomposites. Surface energy of nanocrystalline cellulose (NCC) and some polymers (polypropylene, PP, and polylactic acid, PLA) was measured at room and high temperatures. NCC had higher polarity and surface energy than PP and PLA at room temperature but had a lower surface energy at higher temperatures. The effect of surface modification with alkenyl succinic anhydride (ASA) on NCC surface energy at room and high temperature was studied. Total surface energy of NCC was lowered after surface modification. Thermodynamic work of adhesion for PP/NCC and PLA/NCC was lowered by NCC surface modification. A thermodynamic analysis is proposed to estimate the dispersion energy, based on surface energy measurements at room and high temperatures. Also, a dispersion factor is defined to provide a quantitative indication of the dispersibility of nanoparticles in a polymer matrix under various conditions. The required dispersion energy was reduced by lowering the interfacial tension. On the other hand, it increased as the quality of NCC dispersion (i.e., the nanoparticle surface area) in the system was improved. Surface modification of NCC with ASA had a negative effect on the compatibility between NCC and PLA, whereas it had a positive influence on compatibility between PP and NCC.

  2. Controlled synthesis of high-quality crystals of monolayer MoS2 for nanoelectronic device application

    DEFF Research Database (Denmark)

    Yang, Xiaonian; Li, Qiang; Hu, Guofeng

    2016-01-01

    . Monolayer MoS2 so far can be obtained by mechanical exfoliation or chemical vapor deposition (CVD). However, controllable synthesis of large area monolayer MoS2 with high quality needs to be improved and their growth mechanism requires more studies. Here we report a systematical study on controlled...... synthesis of high-quality monolayer MoS2 single crystals using low pressure CVD. Large-size monolayer MoS2 triangles with an edge length up to 405 mu m were successfully synthesized. The Raman and photoluminescence spectroscopy studies indicate high homogenous optical characteristic of the synthesized......) V-1 s(-1), indicating excellent electronic property comparing with previously reported CVD grown MoS2 monolayer. The MoS2 FETs also show a high photoresponsivity of 7 A W-1, as well as a fast photo-response time of 20 ms. The improved synthesis method recommended here, which makes material...

  3. Quantification of bone quality using different cone beam computed tomography devices: Accuracy assessment for edentulous human mandibles

    OpenAIRE

    Van Dessel, Jeroen; Nicolielo, Laura Ferreira Pinheiro; Huang, Yan; Slagmolen, Pieter; Politis, Constantinus; Lambrichts, Ivo; Jacobs, Reinhilde

    2016-01-01

    Purpose: To determine the accuracy of the latest cone beam computed tomography (CBCT) machines in comparison to multi-slice computer tomography (MSCT) and micro computed tomography (micro CT) for objectively assessing trabecular and cortical bone quality prior to implant placement. Materials and methods: Eight edentulous human mandibular bone samples were scanned with seven CBCT scanners (3D Accuitomo 170, i-CAT Next Generation, ProMax 3D Max, Scanora 3D, Cranex 3D, Newtom GiANO and Carestrea...

  4. First experiences with the implementation of the European standard EN 62304 on medical device software for the quality assurance of a radiotherapy unit.

    Science.gov (United States)

    Höss, Angelika; Lampe, Christian; Panse, Ralf; Ackermann, Benjamin; Naumann, Jakob; Jäkel, Oliver

    2014-03-21

    According to the latest amendment of the Medical Device Directive standalone software qualifies as a medical device when intended by the manufacturer to be used for medical purposes. In this context, the EN 62304 standard is applicable which defines the life-cycle requirements for the development and maintenance of medical device software. A pilot project was launched to acquire skills in implementing this standard in a hospital-based environment (in-house manufacture). The EN 62304 standard outlines minimum requirements for each stage of the software life-cycle, defines the activities and tasks to be performed and scales documentation and testing according to its criticality. The required processes were established for the pre-existent decision-support software FlashDumpComparator (FDC) used during the quality assurance of treatment-relevant beam parameters. As the EN 62304 standard implicates compliance with the EN ISO 14971 standard on the application of risk management to medical devices, a risk analysis was carried out to identify potential hazards and reduce the associated risks to acceptable levels. The EN 62304 standard is difficult to implement without proper tools, thus open-source software was selected and integrated into a dedicated development platform. The control measures yielded by the risk analysis were independently implemented and verified, and a script-based test automation was retrofitted to reduce the associated test effort. After all documents facilitating the traceability of the specified requirements to the corresponding tests and of the control measures to the proof of execution were generated, the FDC was released as an accessory to the HIT facility. The implementation of the EN 62304 standard was time-consuming, and a learning curve had to be overcome during the first iterations of the associated processes, but many process descriptions and all software tools can be re-utilized in follow-up projects. It has been demonstrated that a

  5. First experiences with the implementation of the European standard EN 62304 on medical device software for the quality assurance of a radiotherapy unit

    International Nuclear Information System (INIS)

    Höss, Angelika; Lampe, Christian; Panse, Ralf; Ackermann, Benjamin; Naumann, Jakob; Jäkel, Oliver

    2014-01-01

    According to the latest amendment of the Medical Device Directive standalone software qualifies as a medical device when intended by the manufacturer to be used for medical purposes. In this context, the EN 62304 standard is applicable which defines the life-cycle requirements for the development and maintenance of medical device software. A pilot project was launched to acquire skills in implementing this standard in a hospital-based environment (in-house manufacture). The EN 62304 standard outlines minimum requirements for each stage of the software life-cycle, defines the activities and tasks to be performed and scales documentation and testing according to its criticality. The required processes were established for the pre-existent decision-support software FlashDumpComparator (FDC) used during the quality assurance of treatment-relevant beam parameters. As the EN 62304 standard implicates compliance with the EN ISO 14971 standard on the application of risk management to medical devices, a risk analysis was carried out to identify potential hazards and reduce the associated risks to acceptable levels. The EN 62304 standard is difficult to implement without proper tools, thus open-source software was selected and integrated into a dedicated development platform. The control measures yielded by the risk analysis were independently implemented and verified, and a script-based test automation was retrofitted to reduce the associated test effort. After all documents facilitating the traceability of the specified requirements to the corresponding tests and of the control measures to the proof of execution were generated, the FDC was released as an accessory to the HIT facility. The implementation of the EN 62304 standard was time-consuming, and a learning curve had to be overcome during the first iterations of the associated processes, but many process descriptions and all software tools can be re-utilized in follow-up projects. It has been demonstrated that a

  6. Do surveys with paper and electronic devices differ in quality and cost? Experience from the Rufiji Health and demographic surveillance system in Tanzania.

    Science.gov (United States)

    Mukasa, Oscar; Mushi, Hildegalda P; Maire, Nicolas; Ross, Amanda; de Savigny, Don

    2017-01-01

    Data entry at the point of collection using mobile electronic devices may make data-handling processes more efficient and cost-effective, but there is little literature to document and quantify gains, especially for longitudinal surveillance systems. To examine the potential of mobile electronic devices compared with paper-based tools in health data collection. Using data from 961 households from the Rufiji Household and Demographic Survey in Tanzania, the quality and costs of data collected on paper forms and electronic devices were compared. We also documented, using qualitative approaches, field workers, whom we called 'enumerators', and households' members on the use of both methods. Existing administrative records were combined with logistics expenditure measured directly from comparison households to approximate annual costs per 1,000 households surveyed. Errors were detected in 17% (166) of households for the paper records and 2% (15) for the electronic records (p < 0.001). There were differences in the types of errors (p = 0.03). Of the errors occurring, a higher proportion were due to accuracy in paper surveys (79%, 95% CI: 72%, 86%) compared with electronic surveys (58%, 95% CI: 29%, 87%). Errors in electronic surveys were more likely to be related to completeness (32%, 95% CI 12%, 56%) than in paper surveys (11%, 95% CI: 7%, 17%).The median duration of the interviews ('enumeration'), per household was 9.4 minutes (90% central range 6.4, 12.2) for paper and 8.3 (6.1, 12.0) for electronic surveys (p = 0.001). Surveys using electronic tools, compared with paper-based tools, were less costly by 28% for recurrent and 19% for total costs. Although there were technical problems with electronic devices, there was good acceptance of both methods by enumerators and members of the community. Our findings support the use of mobile electronic devices for large-scale longitudinal surveys in resource-limited settings.

  7. Miniaturized video-microscopy system for near real-time water quality biomonitoring using microfluidic chip-based devices

    Science.gov (United States)

    Huang, Yushi; Nigam, Abhimanyu; Campana, Olivia; Nugegoda, Dayanthi; Wlodkowic, Donald

    2016-12-01

    Biomonitoring studies apply biological responses of sensitive biomonitor organisms to rapidly detect adverse environmental changes such as presence of physic-chemical stressors and toxins. Behavioral responses such as changes in swimming patterns of small aquatic invertebrates are emerging as sensitive endpoints to monitor aquatic pollution. Although behavioral responses do not deliver information on an exact type or the intensity of toxicants present in water samples, they could provide orders of magnitude higher sensitivity than lethal endpoints such as mortality. Despite the advantages of behavioral biotests performed on sentinel organisms, their wider application in real-time and near realtime biomonitoring of water quality is limited by the lack of dedicated and automated video-microscopy systems. Current behavioral analysis systems rely mostly on static test conditions and manual procedures that are time-consuming and labor intensive. Tracking and precise quantification of locomotory activities of multiple small aquatic organisms requires high-resolution optical data recording. This is often problematic due to small size of fast moving animals and limitations of culture vessels that are not specially designed for video data recording. In this work, we capitalized on recent advances in miniaturized CMOS cameras, high resolution optics and biomicrofluidic technologies to develop near real-time water quality sensing using locomotory activities of small marine invertebrates. We present proof-of-concept integration of high-resolution time-resolved video recording system and high-throughput miniaturized perfusion biomicrofluidic platform for optical tracking of nauplii of marine crustacean Artemia franciscana. Preliminary data demonstrate that Artemia sp. exhibits rapid alterations of swimming patterns in response to toxicant exposure. The combination of video-microscopy and biomicrofluidic platform facilitated straightforward recording of fast moving objects. We

  8. Preparation and mechanical properties of ultra-high-strength nanocrystalline metals

    Czech Academy of Sciences Publication Activity Database

    Marek, I.; Vojtěch, D.; Michalcová, A.; Kubatík, Tomáš František

    2015-01-01

    Roč. 15, č. 4 (2015), s. 596-600 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Mechanical properties * Nanocrystalline materials * Selective leaching * Silver * Spark plasma sintering Subject RIV: JG - Metallurgy

  9. Microstructures and mechanical properties of nanocrystalline NiTi intermetallics formed by mechanosynthesis

    Science.gov (United States)

    Arunkumar, S.; Kumaravel, P.; Velmurugan, C.; Senthilkumar, V.

    2018-01-01

    The formulation of nanocrystalline NiTi shape memory alloys has potential effects in mechanical stimulation and medical implantology. The present work elucidates the effect of milling time on the product's structural characteristics, chemical composition, and microhardness for NiTi synthesized by mechanical alloying for different milling durations. Increasing the milling duration led to the formation of a nanocrystalline NiTi intermetallic at a higher level. The formation of nanocrystalline materials was directed through cold fusion, fracturing, and the development of a steady state, which were influenced by the accumulation of strain energy. In the morphological study, uninterrupted cold diffusion and fracturing were visualized using transmission electron microscopy. Particle size analysis revealed that the mean particle size was reduced to 93 μm after 20 h of milling. The mechanical strength was enhanced by the formation of a nanocrystalline intermetallic phase at longer milling time, which was confirmed by the results of Vickers hardness analyses.

  10. Towards lightweight and flexible high performance nanocrystalline silicon solar cells through light trapping and transport layers

    Science.gov (United States)

    Gray, Zachary R.

    This thesis investigates ways to enhance the efficiency of thin film solar cells through the application of both novel nano-element array light trapping architectures and nickel oxide hole transport/electron blocking layers. Experimental results independently demonstrate a 22% enhancement in short circuit current density (JSC) resulting from a nano-element array light trapping architecture and a ˜23% enhancement in fill factor (FF) and ˜16% enhancement in open circuit voltage (VOC) resulting from a nickel oxide transport layer. In each case, the overall efficiency of the device employing the light trapping or transport layer was superior to that of the corresponding control device. Since the efficiency of a solar cell scales with the product of JSC, FF, and VOC, it follows that the results of this thesis suggest high performance thin film solar cells can be realized in the event light trapping architectures and transport layers can be simultaneously optimized. The realizations of these performance enhancements stem from extensive process optimization for numerous light trapping and transport layer fabrication approaches. These approaches were guided by numerical modeling techniques which will also be discussed. Key developments in this thesis include (1) the fabrication of nano-element topographies conducive to light trapping using various fabrication approaches, (2) the deposition of defect free nc-Si:H onto structured topographies by switching from SiH4 to SiF 4 PECVD gas chemistry, and (3) the development of the atomic layer deposition (ALD) growth conditions for NiO. Keywords: light trapping, nano-element array, hole transport layer, electron blocking layer, nickel oxide, nanocrystalline silicon, aluminum doped zinc oxide, atomic layer deposition, plasma enhanced chemical vapor deposition, electron beam lithography, ANSYS HFSS.

  11. Current Status of the Quality of 4H-SiC Substrates and Epilayers for Power Device Applications

    Energy Technology Data Exchange (ETDEWEB)

    Dudley, M.; Wang, H.; Guo, Jianqiu; Yang, Yu; Raghothamachar, Balaji; Zhang, J.; Thomas, B.; Chung, G.; Sanchez, E. K.; Hansen, D.; Mueller, S. G.

    2016-01-01

    ABSTRACT

    Interfacial dislocations (IDs) and half-loop arrays (HLAs) present in the epilayers of 4H-SiC crystal are known to have a deleterious effect on device performance. Synchrotron X-ray Topography studies carried out on n-type 4H-SiC offcut wafers before and after epitaxial growth show that in many cases BPD segments in the substrate are responsible for creating IDs and HLAs during CVD growth. This paper reviews the behaviors of BPDs in the substrate during the epitaxial growth in different cases: (1) screw-oriented BPD segments intersecting the surface replicate directly through the interface during the epitaxial growth and take part in stress relaxation process by creating IDs and HLAs (Matthews-Blakeslee model [1] ); (2) non-screw oriented BPD half loop intersecting the surface glides towards and replicates through the interface, while the intersection points convert to threading edge dislocations (TEDs) and pin the half loop, leaving straight screw segments in the epilayer and then create IDs and HLAs; (3) edge oriented short BPD segments well below the surface get dragged towards the interface during epitaxial growth, leaving two long screw segments in their wake, some of which replicate through the interface and create IDs and HLAs. The driving force for the BPDs to glide toward the interface is thermal stress and driving force for the relaxation process to occur is the lattice parameter difference at growth temperature which results from the doping concentration difference between the substrate and epilayer.

  12. Topological characterization of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites

    Science.gov (United States)

    Bhat, A. H.; Dasan, Y. K.; Khan, Ihsan Ullah; Ahmad, Faiz; Ayoub, Muhammad

    2016-11-01

    This study was conducted to evaluate the morphological and barrier properties of nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites. Nanocrystalline cellulose was isolated from waste oil palm empty fruit bunch fiber using Sulphuric acid hydrolysis. Chemical modifications of nanocrystalline cellulose was performed to allow good compatibilization between fiber and the polymer matrices and also to improve dispersion of fillers. Bionanocomposite materials were produced from these nanocrystalline cellulose reinforced Poly (lactic acid) and Poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) using solvent casting and evaporation techniques. The properties of extracted nanocrystalline cellulose were examined using FT-IR spectroscopy, X-ray diffractometer, TEM and AFM. Besides that, the properties of bionanocomposites were examined through FESEM and oxygen permeability properties analysis. Better barrier and morphological properties were obtained for nanocrystalline cellulose reinforced bionanocomposites than for neat polymer blend.

  13. Formation of a nanocrystalline layer on the surface of stone wool fibers

    DEFF Research Database (Denmark)

    Yue, Yuanzheng; Korsgaard, Martin; Kirkegaard, Lise Frank

    2009-01-01

    In the present paper, we report a simple approach for creating a nanocrystalline layer on the surface of stone wool fibers (SWFs) with a basalt-like composition. The approach is based on a preoxidation process of the SWFs in atmospheric air at a temperature around the glass transition temperature....... The nanocrystalline layer plays a significant role in enhancing the high-temperature stability of the SWFs....

  14. Influence of pH on ZnO nanocrystalline thin films prepared by sol ...

    Indian Academy of Sciences (India)

    Abstract. ZnO nanocrystalline thin films have been prepared on glass substrates by sol–gel dip coating method. ZnO thin films have been coated at room temperature and at four different pH values of 4, 6, 8 and 10. The. X-ray diffraction pattern showed that ZnO nanocrystalline thin films are of hexagonal structure and the ...

  15. Multiple magnetic scattering in small-angle neutron scattering of Nd?Fe?B nanocrystalline magnet

    OpenAIRE

    Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta

    2016-01-01

    We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd?Fe?B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd?Fe?B nanocrystalline magnet. It is considered that th...

  16. Nanocrystalline sp{sup 2} and sp{sup 3} carbons: CVD synthesis and applications

    Energy Technology Data Exchange (ETDEWEB)

    Terranova, M. L. [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy); Rossi, M. [Università degli Studi di Roma “Sapienza,” via A. Scarpa, Dipartimento di Scienze di Base e Applicate per l’Ingegneria and Centro di Ricerca per le Nanotecnologie Applicate all’Ingegneria (CNIS) (Italy); Tamburri, E., E-mail: emanuela.tamburri@uniroma2.it [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy)

    2016-11-15

    The design and production of innovative materials based on nanocrystalline sp{sup 2}- and sp{sup 3}-coordinated carbons is presently a focus of the scientific community. We present a review of the nanostructures obtained in our labs using a series of synthetic routes, which make use of chemical vapor deposition (CVD) techniques for the selective production of non-planar graphitic nanostructures, nanocrystalline diamonds, and hybrid two-phase nanostructures.

  17. Electrodeposited nanocrystalline Ni-Co and Co-Ni-P coatings for hard chromium replacement

    OpenAIRE

    Ma, Chao

    2013-01-01

    This thesis describes the preparation and characterisation of environmentally friendly and low-cost nanocrystalline Ni-Co coatings and Co-Ni-P coatings to replace hard chromium coatings for anti-wear and anti-corrosion applications. nanocrystalline Ni–Co coatings with different cobalt contents were electrodeposited.The investigation on the role of tribofilms and wear debris in the tribological behavior sliding against AISI-52100 stainless steel under unlubricated conditions shows that the tri...

  18. Silver film on nanocrystalline TiO{sub 2} support: Photocatalytic and antimicrobial ability

    Energy Technology Data Exchange (ETDEWEB)

    Vukoje, Ivana D., E-mail: ivanav@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Tomašević-Ilić, Tijana D., E-mail: tommashev@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Zarubica, Aleksandra R., E-mail: zarubica2000@yahoo.com [Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš (Serbia); Dimitrijević, Suzana, E-mail: suzana@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Budimir, Milica D., E-mail: mickbudimir@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Vranješ, Mila R., E-mail: mila@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Šaponjić, Zoran V., E-mail: saponjic@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Nedeljković, Jovan M., E-mail: jovned@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia)

    2014-12-15

    Highlights: • Simple photocatalytic rout for deposition of Ag on nanocrystalline TiO{sub 2} films. • High antibactericidal efficiency of deposited Ag on TiO{sub 2} support. • Improved photocatalytic performance of TiO{sub 2} films in the presence of deposited Ag. - Abstract: Nanocrystalline TiO{sub 2} films were prepared on glass slides by the dip coating technique using colloidal solutions consisting of 4.5 nm particles as a precursor. Photoirradiation of nanocrystalline TiO{sub 2} film modified with alanine that covalently binds to the surface of TiO{sub 2} and at the same time chelate silver ions induced formation of metallic silver film. Optical and morphological properties of thin silver films on nanocrystalline TiO{sub 2} support were studied by absorption spectroscopy and atomic force microscopy. Improvement of photocatalytic performance of nanocrystalline TiO{sub 2} films after deposition of silver was observed in degradation reaction of crystal violet. Antimicrobial ability of deposited silver films on nanocrystalline TiO{sub 2} support was tested in dark as a function of time against Escherichia coli, Staphylococcus aureus, and Candida albicans. The silver films ensured maximum cells reduction of both bacteria, while the fungi reduction reached satisfactory 98.45% after 24 h of contact.

  19. Hot pressing of nanocrystalline tantalum using high frequency induction heating and pulse plasma sintering

    Science.gov (United States)

    Jakubowicz, J.; Adamek, G.; Sopata, M.; Koper, J. K.; Siwak, P.

    2017-12-01

    The paper presents the results of nanocrystalline powder tantalum consolidation using hot pressing. The authors used two different heating techniques during hot pressing: high-frequency induction heating (HFIH) and pulse plasma sintering (PPS). A comparison of the structure, microstructure, mechanical properties and corrosion resistance of the bulk nanocrystalline tantalum obtained in both techniques was performed. The nanocrystalline powder was made to start from the microcrystalline one using the high-energy ball milling process. The nanocrystalline powder was hot-pressed at 1000 °C, whereas, for comparison, the microcrystalline powder was hot pressed up to 1500 °C for proper consolidation. The authors found that during hot pressing, the powder partially reacts with the graphite die covered by boron nitride, which facilitated punches and powder displacement in the die during densification. Tantalum carbide and boride in the nanocrystalline material was found, which can improve the mechanical properties. The hardness of the HFIH and PPS nanocrystalline tantalum was as high as 625 and 615 HV, respectively. The microstructure was more uniform in the PPS nanomaterial. The corrosion resistance in both cases deteriorated, in comparison to the microcrystalline material, while the PPS material corrosion resistance was slightly better than that of the HFIH one.

  20. Draft formal response to Agency for Healthcare Research and Quality (AHRQ) Technical Brief on neurothrombectomy devices in acute ischemic stroke.

    Science.gov (United States)

    Khalessi, Alexander A; Natarajan, Sabareesh K; Binning, Mandy J; Siddiqui, Adnan S; Levy, Elad; Hopkins, L Nelson

    2010-06-01

    In the current environment of health policy reform, physicians must increasingly engage the federal system to inform the government regarding the state of the science and to advocate on behalf of their patients for the continued provision of necessary care. The Agency of Health Research and Quality (AHRQ), within the Department of Health and Human Services (DHHS), provides scientific advice to the Centers for Medicare and Medicaid Services (CMS) regarding the efficacy and cost-effectiveness of existing therapeutic modalities. These Technical Briefs provide the scientific basis for Medicare reimbursement policies. Recently, the AHRQ produced a Draft Technical Brief on Mechanical Thrombectomy for Acute Ischemic Stroke. This document potentially endangers future reimbursement for endovascular stroke care. The link to the Technical Brief is: http://effectivehealthcare.ahrq.gov/index.cfm/research-available-forcomment/comment-draftreports/?pageactiondisplaydraftcommentform&topicid161&productid418&documenttypedraftReport. The endovascular neurosurgery group at the University of Buffalo produced a formal response. The following FORUM piece represents this response, and draws upon their substantial institutional experience. This piece will likely provide the foundation for a larger, multispecialty response, including American Association of Neurological Surgeons/Congress of Neurological Surgeons, SCAI, and possibly SNIS. Coordination of such an effort remains a work in progress. This piece offers the amalgam of policy and science central to WORLD NEUROSURGERY and provides a timely window to an evolving policy with dramatic implications for the neurosurgery community. Copyright © 2010. Published by Elsevier Inc.

  1. Nanocrystalline hydroxyapatite prepared under various pH conditions

    Science.gov (United States)

    Palanivelu, R.; Mary Saral, A.; Ruban Kumar, A.

    2014-10-01

    Hydroxyapatite (HAP) has sovereign biomedical application due to its excellent biocompatibility, chemical and crystallographic similitude with natural human bone. In this present work, we discussed about the role of pH in the synthesis of calcium phosphate compound using calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate as starting materials by chemical precipitation method assisted with ultrasonic irradiation technique. 5% polyethylene glycol (PEG600) is added along with the precursors under various pH condition of 7, 9 and 11 respectively. The functional group analysis, crystallized size and fraction of crystallized size are confirmed using Fourier Transformation Infra-Red spectroscopy and X-ray diffraction pattern. Morphological observations are done by scanning electron microscope. The results revealed the presence of nanocrystalline hydroxyapatite at pH above 9.

  2. Nanocrystalline diamond in carbon implanted SiO{sub 2}.

    Energy Technology Data Exchange (ETDEWEB)

    Tsoi, K.A.; Prawer, S.; Nugent, K.W.; Walker, R. J.; Weiser, P.S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Recently, it was reported that nanocrystalline diamond can be produced via laser annealing of a high dose C implanted fused quartz (SiO{sub 2}) substrate. The aim of this investigation is to reproduce this result on higher C{sup +} dose samples and the non-implanted silicon sample, as well as optimise the power range and annealing time for the production of these nanocrystals of diamond. In order to provide a wide range of laser powers the samples were annealed using an Ar ion Raman laser. The resulting annealed spots were analysed using scanning electron microscopy (SEM) and Raman analysis. These techniques are employed to determine the type of bonding produced after laser annealing has occurred. 4 refs., 5 figs.

  3. Grain boundaries and mechanical properties of nanocrystalline diamond films.

    Energy Technology Data Exchange (ETDEWEB)

    Busmann, H.-G.; Pageler, A.; Gruen, D. M.

    1999-08-06

    Phase-pure nanocrystalline diamond thin films grown from plasmas of a hydrogen-poor carbon argon gas mixture have been analyzed regarding their hardness and elastic moduli by means of a microindentor and a scanning acoustic microscope.The films are superhard and the moduli rival single crystal diamond. In addition, Raman spectroscopy with an excitation wavelength of 1064 nm shows a peak at 1438 l/cm and no peak above 1500 l/cm, and X-ray photoelectron spectroscopy a shake-up loss at 4.2 eV. This gives strong evidence for the existence of solitary double bonds in the films. The hardness and elasticity of the films then are explained by the assumption, that the solitary double bonds interconnect the nanocrystals in the films, leading to an intergrain boundary adhesion of similar strength as the intragrain diamond cohesion. The results are in good agreement with recent simulations of high-energy grain boundaries.

  4. 1H-15N correlation spectroscopy of nanocrystalline proteins

    International Nuclear Information System (INIS)

    Morcombe, Corey R.; Paulson, Eric K.; Gaponenko, Vadim; Byrd, R. Andrew; Zilm, Kurt W.

    2005-01-01

    The limits of resolution that can be obtained in 1 H- 15 N 2D NMR spectroscopy of isotopically enriched nanocrystalline proteins are explored. Combinations of frequency switched Lee-Goldburg (FSLG) decoupling, fast magic angle sample spinning (MAS), and isotopic dilution via deuteration are investigated as methods for narrowing the amide 1 H resonances. Heteronuclear decoupling of 15 N from the 1 H resonances is also studied. Using human ubiquitin as a model system, the best resolution is most easily obtained with uniformly 2 H and 15 N enriched protein where the amides have been exchanged in normal water, MAS at ∼20 kHz, and WALTZ-16 decoupling of the 15 N nuclei. The combination of these techniques results in average 1 H lines of only ∼0.26 ppm full width at half maximum. Techniques for optimizing instrument stability and 15 N decoupling are described for achieving the best possible performance in these experiments

  5. Nanocrystalline metal-superconductor powders produced by aerosol decomposition

    International Nuclear Information System (INIS)

    Carim, A.H.; Doherty, P.; Kodas, T.T.

    1990-01-01

    This paper reports on composite silver---YBa 2 Cu 3 O 7-δ powders with nanocrystalline and larger sizes produced by aerosol techniques at 1000 degrees C and 930 degrees C. Silver is incorporated primarily in the elemental form, although particles of hexagonal Ag 2 O are also observed when the reactor is operated below the Ag-O eutectic temperature (939 degree C). Longer reactor residence times (>35 s, as opposed to c > 90K) can still be obtained in the composite powders. Aerosol decomposition of Y-Ba-Cu nitrate precursors with Pt additions did not produce superconductive material; instead, most of the resultant particles were Pt-Y-Ba-Cu-O compounds

  6. Science at the interface : grain boundaries in nanocrystalline metals.

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Mark Andrew; Follstaedt, David Martin; Knapp, James Arthur; Brewer, Luke N.; Holm, Elizabeth Ann; Foiles, Stephen Martin; Hattar, Khalid M.; Clark, Blythe B.; Olmsted, David L.; Medlin, Douglas L.

    2009-09-01

    Interfaces are a critical determinant of the full range of materials properties, especially at the nanoscale. Computational and experimental methods developed a comprehensive understanding of nanograin evolution based on a fundamental understanding of internal interfaces in nanocrystalline nickel. It has recently been shown that nanocrystals with a bi-modal grain-size distribution possess a unique combination of high-strength, ductility and wear-resistance. We performed a combined experimental and theoretical investigation of the structure and motion of internal interfaces in nanograined metal and the resulting grain evolution. The properties of grain boundaries are computed for an unprecedented range of boundaries. The presence of roughening transitions in grain boundaries is explored and related to dramatic changes in boundary mobility. Experimental observations show that abnormal grain growth in nanograined materials is unlike conventional scale material in both the level of defects and the formation of unfavored phases. Molecular dynamics simulations address the origins of some of these phenomena.

  7. Raman Studies of Nanocrystalline CdS:O Film

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Wu, X.; Dhere, R.; Zhou, J.; Yan, Y.; Mascarenhas, A.

    2005-01-01

    Oxygenated nanocrystalline CdS films show improved solar cell performance, but the physics and mechanism underlying this are not yet clearly understood. Raman study provides complementary information to the understanding obtained from other experimental investigations. A comprehensive analysis of the existing experimental data (including x-ray diffraction, transmission, transmission electron microscopy, and Raman) has led to the following conclusions: (1) The O-incorporation forms CdS1-xOx alloy nano-particles. (2) The observed evolution of the electronic structure is the result of the interplay between the alloy and quantum confinement effect. (3) The blue-shift of the LO phonon Raman peak is primarily due to the alloying effect. (4) Some oxygen atoms have taken the interstitial sites.

  8. Synthesis and characterization of a nanocrystalline diamond aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Jr., Joe H.

    2011-07-06

    Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

  9. Relaxation and grain growth behavior of nanocrystalline iron

    International Nuclear Information System (INIS)

    Holzer, J.C.; Eckert, J.; Krill, C.E. III; Johnson, W.L.

    1992-01-01

    Nanocrystalline Fe has been prepared by inert gas condensation and ball milling. The kinetics of relaxation and grain growth are investigated by differential scanning calorimetry. The development of the microstructure is monitored by x-ray powder diffraction and transmission electron microscopy. Emphasis is placed on the differences observed for samples prepared by the two different techniques. In this paper, the authors find that the kinetics of relaxation and grain growth are very sensitive to the sample preparation method. Samples with the same initial average grain size, as determined by the peak broadening in x-ray diffraction, show very different recovery behavior. The differences are discussed in terms of the estimated grain boundary energies and the initial grain size distribution obtained by the two preparation techniques

  10. Properties and processing of nanocrystalline materials. Quarterly report

    Energy Technology Data Exchange (ETDEWEB)

    Valiev, R.Z.

    1996-01-22

    The present Report completes the investigations in the frame of the project for the first year. It is important to estimate our achievements in the investigation of properties of nanocrystalline materials obtained by severe plastic deformation and their production. We think that the main results obtained can be summarized as follows: (1) We performed an improvement of the die-set for equal channel (ECA) pressing and torsion under high pressure with the aim to increase dimensions of the samples produced and to conduct processing of low ductile materials. (2) It was established that in pure metals severe plastic deformation led to the formation of an ultra fine-grained structure with a mean grain size of 100-200 nm, while in alloys due to severe plastic deformation and/or special methods of treatment (a decrease in the temperature of deformation, an increase of the pressure applied etc.) the grain size could be decreased down to a few tens of manometers.

  11. Torsion-induced magnetoimpedance in nanocrystalline Fe-based wires

    International Nuclear Information System (INIS)

    Santos, J.D.; Olivera, J.; Alvarez, P.; Sanchez, T.; Perez, M.J.; Sanchez, M.L.; Gorria, P.; Hernando, B.

    2007-01-01

    The magnetic field influence on the real and imaginary parts of axial-diagonal (ζ zz ) and off-diagonal (ζ φz ) components of the surface magnetoimpedance (MI) tensor has been studied in amorphous and nanocrystalline Fe 73.5 Si 13.5 B 9 Cu 1 Nb 3 wires. Twisted and untwisted wires were annealed at a temperature near to that of primary crystallization. The MI response has been measured at 1MHz and 5mA rms drive current in all the samples. Even though the higher values for both components of the MI tensor are achieved for the untwisted annealed wire, the most interesting features are observed in the torsion annealed wire

  12. Temperature Dependent Variations of Phonon Interactions in Nanocrystalline Cerium Oxide

    Directory of Open Access Journals (Sweden)

    Sugandha Dogra Pandey

    2015-01-01

    Full Text Available The temperature dependent anharmonic behavior of the phonon modes of nanocrystalline CeO2 was investigated in the temperature range of 80–440 K. The anharmonic constants have been derived from the shift in phonon modes fitted to account for the anharmonic contributions as well as the thermal expansion contribution using the high pressure parameters derived from our own high pressure experimental data reported previously. The total anharmonicity has also been estimated from the true anharmonicity as well as quasiharmonic component. In the line-width variation analysis, the cubic anharmonic term was found to dominate the quartic term. Finally, the phonon lifetime also reflected the trend so observed.

  13. Low-temperature creep of nanocrystalline titanium(IV) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, H.; Averback, R.S. (Dept. of Materials Sceince and Engineering, Univ. of Illinois, Urbana, IL (United States))

    1991-11-01

    This paper reports that nanocrystalline TiO[sub 2] with densities higher than 99% of rutile has been deformed in compression without fracture at temperatures between 600[degrees] and 800[degrees] C. The total strains exceed 0.6 at strain rates as high as 10[sup [minus]3] s[sup [minus]1]. The original average grain size of 40 nm increases during the creep deformation to final values in the range of 120 to 1000 nm depending on the temperature and total deformation. The stress exponent of the strain rate, n, is approximately 3 and the grain size dependence is d[sup [minus]q] with q in the range of 1 to 1.5. It is concluded that the creep deformation occurs by an interface reaction controlled mechanism.

  14. Nanocrystalline Al Composites from Powder Milled under Ammonia Gas Flow

    Directory of Open Access Journals (Sweden)

    J. Cintas

    2014-01-01

    Full Text Available The production of high hardness and thermally stable nanocrystalline aluminium composites is described. Al powder was milled at room temperature in an ammonia flow for a period of less than 5 h. NH3 dissociation during milling provokes the absorption, at a high rate, of nitrogen into aluminium, hardening it by forming a solid solution. Controlled amounts of AlN and Al5O6N are formed during the subsequent sintering of milled powders for consolidation. The pinning action of these abundant dispersoids highly restrains aluminium grain growth during heating. The mean size of the Al grains remains below 45 nm and even after the milled powder is sintered at 650°C for 1 h.

  15. Mechanically Enhanced Liquid Interfaces at Human Body Temperature Using Thermosensitive Methylated Nanocrystalline Cellulose.

    Science.gov (United States)

    Scheuble, N; Geue, T; Kuster, S; Adamcik, J; Mezzenga, R; Windhab, E J; Fischer, P

    2016-02-09

    The mechanical performance of materials at oil/water interfaces after consumption is a key factor affecting hydrophobic drug release. In this study, we methylated the surface of nanocrystalline cellulose (NCC) by mercerization and dimethyl sulfate exposure to produce thermosensitive biopolymers. These methylated NCC (metNCC) were used to investigate interfacial thermogelation at air/water and medium-chain triglyceride (MCT)/water interfaces at body temperature. In contrast to bulk fluid dynamics, elastic layers were formed at room temperature, and elasticity increased significantly at body temperature, which was measured by interfacial shear and dilatational rheology in situ. This unique phenomenon depends on solvent quality, temperature, and polymer concentration at interfaces. Thus, by adjusting the degree of hydrophobicity of metNCC, the interfacial elasticity and thermogelation of the interfaces could be varied. In general, these new materials (metNCC) formed more brittle interfacial layers compared to commercial methylcellulose (MC A15). Thermogelation of methylcellulose promotes attractive intermolecular forces, which were reflected in a change in self-assembly of metNCC at the interface. As a consequence, layer thickness and density increased as a function of temperature. These effects were measured by atomic force microscopy (AFM) images of the displaced interface and confirmed by neutron reflection. The substantial structural and mechanical change of methylcellulose interfaces at body temperature represents a controllable encapsulation parameter allowing optimization of lipid-based drug formulations.

  16. Charge carrier transport mechanisms in nanocrystalline indium oxide

    International Nuclear Information System (INIS)

    Forsh, E.A.; Marikutsa, A.V.; Martyshov, M.N.; Forsh, P.A.; Rumyantseva, M.N.; Gaskov, A.M.; Kashkarov, P.K.

    2014-01-01

    The charge transport properties of nanocrystalline indium oxide (In 2 O 3 ) are studied. A number of nanostructured In 2 O 3 samples with various nanocrystal sizes are prepared by sol–gel method and characterized using various techniques. The mean nanocrystals size varies from 7–8 nm to 18–20 nm depending on the conditions of their preparation. Structural characterizations of the In 2 O 3 samples are performed by means of transmission electron microscopy and X-ray diffraction. The analysis of dc and ac conductivity in a wide temperature range (T = 50–300 K) shows that at high temperatures charge carrier transport takes place over conduction band and at low temperatures a variable range hopping transport mechanism can be observed. We find out that the temperature of transition from one mechanism to another depends on nanocrystal size: the transition temperature rises when nanocrystals are bigger in size. The average hopping distance between two sites and the activation energy are calculated basing on the analysis of dc conductivity at low temperature. Using random barrier model we show a uniform hopping mechanism taking place in our samples and conclude that nanocrystalline In 2 O 3 can be regarded as a disordered system. - Highlights: • In 2 O 3 samples with various nanocrystal sizes are prepared by sol–gel method. • The mean nanocrystal size varies from 7–8 nm to 18–20 nm. • At high temperatures charge carrier transport takes place over conduction band. • At low temperatures a variable range hopping transport mechanism can be observed. • We show a uniform hopping mechanism taking place in our samples

  17. Nanocrystalline hydroxyapatite doped with magnesium and zinc: Synthesis and characterization

    International Nuclear Information System (INIS)

    Kalita, Samar J.; Bhatt, Himesh A.

    2007-01-01

    During recent years, there have been efforts in developing nanocrystalline bioceramics, to enhance their mechanical and biological properties for use in tissue engineering applications. In this research, we made an attempt to synthesize nanocrystalline bioactive hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) ceramic powder in the lower-end of nano-range (2-10 nm), using a simple low-temperature sol-gel technique and studied its densification behavior. We further studied the effects of metal ion dopants during synthesis on powder morphology, and the properties of the sintered structures. Calcium nitrate and triethyl phosphite were used as precursors for calcium and phosphorous, respectively, for sol-gel synthesis. Calculated quantities of magnesium oxide and zinc oxide were incorporated as dopants into amorphous dried powder, prior to calcination at 250-550 o C. The synthesized powders were analyzed for their phases using X-ray diffraction technique and characterized for powder morphology and particle size using transmission electron microscopy (TEM). TEM analysis showed that the average particle size of the synthesized powders were in the range of 2-10 nm. The synthesized nano-powders were uniaxially compacted and then sintered at 1250 o C and 1300 o C for 6 h, separately, in air. A maximum average sintered density of 3.29 g/cm 3 was achieved in structures sintered at 1300 o C, developed from nano-powder doped with magnesium. Vickers hardness testing was performed to determine the hardness of the sintered structures. Uniaxial compression tests were performed to evaluate the mechanical properties. Bioactivity and biodegradation behavior of the sintered structures were assessed in simulated body fluid (SBF) and maintained in a dynamic state

  18. Nanocrystalline Fe-Pt alloys. Phase transformations, structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, J.V.

    2006-12-21

    This work has been devoted to the study of phase transformations involving chemical ordering and magnetic properties evolution in bulk Fe-Pt alloys composed of nanometersized grains. Nanocrystalline Fe{sub 100-x}Pt{sub x} (x=40-60) alloys have been prepared by mechanical ball milling of elemental Fe and Pt powders at liquid nitrogen temperature. The as-milled Fe-Pt alloys consist of {proportional_to} 100 {mu}m sized particles constituted by randomly oriented grains having an average size in the range of 10-40 nm. Depending on the milling time, three major microstructure types have been obtained: samples with a multilayer-type structure of Fe and Pt with a thickness of 20-300 nm and a very thin (several nanometers) A1 layer at their interfaces (2 h milled), an intermediate structure, consisting of finer lamellae of Fe and Pt (below approximately 100 nm) with the A1 layer thickness reaching several tens of nanometers (4 h milled) and alloys containing a homogeneous A1 phase (7 h milled). Subsequent heat treatment at elevated temperatures is required for the formation of the L1{sub 0} FePt phase. The ordering develops via so-called combined solid state reactions. It is accompanied by grain growth and thermally assisted removal of defects introduced by milling and proceeds rapidly at moderate temperatures by nucleation and growth of the ordered phases with a high degree of the long-range order. In a two-particle interaction model elaborated in the present work, the existence of hysteresis in recoil loops has been shown to arise from insufficient coupling between the low- and the high-anisotropy particles. The model reveals the main features of magnetisation reversal processes observed experimentally in exchange-coupled systems. Neutron diffraction has been used for the investigation of the magnetic structure of ordered and partially ordered nanocrystalline Fe-Pt alloys. (orig.)

  19. Nanocrystalline zinc ferrite films studied by magneto-optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lišková-Jakubisová, E., E-mail: liskova@karlov.mff.cuni.cz; Višňovský, Š. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, Prague (Czech Republic); Široký, P.; Hrabovský, D.; Pištora, J. [Nanotechnology Center, VŠB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Sahoo, Subasa C. [Department of Physics, Central University of Kerala, Kasaragod, Kerala 671314 (India); Prasad, Shiva [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Bohra, Murtaza [Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa (Japan); Krishnan, R. [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS-UVSQ, 45 Avenue des Etats-Unis, 78935 Versailles (France)

    2015-05-07

    Ferrimagnetic Zn-ferrite (ZnFe{sub 2}O{sub 4}) films can be grown with the ferromagnetic resonance linewidth of 40 Oe at 9.5 GHz without going through a high temperature processing. This presents interest for applications. The work deals with laser ablated ZnFe{sub 2}O{sub 4} films deposited at O{sub 2} pressure of 0.16 mbar onto fused quartz substrates. The films about 120 nm thick are nanocrystalline and their spontaneous magnetization, 4πM{sub s}, depends on the nanograin size, which is controlled by the substrate temperature (T{sub s}). At T{sub s} ≈ 350 °C, where the grain distribution peaks around ∼20–30 nm, the room temperature 4πM{sub s} reaches a maximum of ∼2.3 kG. The films were studied by magnetooptical polar Kerr effect (MOKE) spectroscopy at photon energies between 1 and 5 eV. The complementary characteristics were provided by spectral ellipsometry (SE). Both the SE and MOKE spectra confirmed ferrimagnetic ordering. The structural details correspond to those observed in MgFe{sub 2}O{sub 4} and Li{sub 0.5}Fe{sub 2.5}O{sub 4} spinels. SE experiments confirm the insulator behavior. The films display MOKE amplitudes somewhat reduced with respect to those in Li{sub 0.5}Fe{sub 2.5}O{sub 4} and MgFe{sub 2}O{sub 4} due to a lower degree of spinel inversion and nanocrystalline structure. The results indicate that the films are free of oxygen vacancies and Fe{sup 3+}-Fe{sup 2+} exchange.

  20. Effect of phase transitions on thermoluminescence characteristics of nanocrystalline alumina

    International Nuclear Information System (INIS)

    Rani, Geeta; Sahare, P.D.

    2013-01-01

    Highlights: •Synthesis of Al 2 O 3 nanocrystalline TLD phosphor. •Material characterizations by XRD, TEM and TL. •Change in structure and morphology of the phase transition alumina. •Change in glow curve structures and trapping parameters on phase transitions. -- Abstract: Nanocrystalline boehmite (γ-AlOOH) was synthesized by hydrothermal method using AlCl 3 ·6H 2 O and Urea as precursors. The material gets decomposed to form the γ-Al 2 O 3 phase at around 873 K on annealing in air. On annealing further at higher temperatures it gets converted into different phases, such as, δ, θ and the most stable α-phase. Not only the phase changes but the annealing has also changed the morphology of the nanomaterial, i.e. it has changed from spindle like edges to vermicular structures and also grew bigger in sizes. The formations of different phases were confirmed by the X-ray diffraction (XRD) patterns and the changes in the morphology were seen through the TEM images. Further the effect of different phases on the thermoluminescence (TL) glow curve structures was studied and it is also shown that the TL glow curves structures do change due to phase transformations. To investigate further and to determine trapping parameters, different glow curves have been theoretically deconvoluted using computerized glow curve deconvolution (CGCD method) into simple glow peaks. The values of different trapping parameters also change as the glow curve structures on phase transformations due to reorganization of energy levels and the stress/strain generated by some intermediate phases

  1. Phase Competition Induced Bio-Electrochemical Resistance and Bio-Compatibility Effect in Nanocrystalline Zr x -Cu100-xThin Films.

    Science.gov (United States)

    Badhirappan, Geetha Priyadarshini; Nallasivam, Vignesh; Varadarajan, Madhuri; Leobeemrao, Vasantha Priya; Bose, Sivakumar; Venugopal, Elakkiya; Rajendran, Selvakumar; Angleo, Peter Chrysologue

    2018-07-01

    Nano-crystalline Zrx-Cu100-x (x = 20-100 at.%) thin films with thickness ranging from 50 to 185 nm were deposited by magnetron co-sputtering with individual Zr and Cu targets. The as-sputtered thin films were characterized by Field Emission Scanning Electron Microscope (FE-SEM), Atomic Force Microscopy (AFM) and Glancing Incidence X-ray Diffraction (GIXRD) for structural and morphological properties. The crystallite size was found to decrease from 57 nm to 37 nm upon increasing the Zr content from 20 to 30 at.% with slight increase in the lattice strain from 0.17 to 0.33%. Further, increase in Zr content to 40 at.% leads to increase in the crystallite size to 57 nm due to stabilization of C10Zr7 phase along with the presence of nanocrystalline Cu-Zr phase. A bimodal distribution of grain size was observed from FE-SEM micrograph was attributed to the highest surface roughness in Zr30Cu70 thin films comprised of Cu10Zr7, Cu9Zr2, Cu-Zr intermetallic phases. In-vitro electrochemical behaviors of nano-crystalline Zrx-Cu100-x thin films in simulated body fluid (SBF) were investigated using potentiodynamic polarization studies. Electrochemical impedance spectroscopy (EIS) data fitting by equivalent electrical circuit fit model suggests that inner bulk layer contributes to high bio-corrosion resistance in Zrx-Cu100-x thin films with increase in Zr content. The results of cyto-compatibility assay suggested that Zr-Cu thin film did not introduce cytotoxicity to osteoblast cells, indicating its suitability as a bio-coating for minimally invasive medical devices.

  2. High-quality III-V semiconductor MBE growth on Ge/Si virtual substrates for metal-oxide-semiconductor device fabrication

    Science.gov (United States)

    Choi, Donghun; Harris, James S.; Kim, Eunji; McIntyre, Paul C.; Cagnon, Joel; Stemmer, Susanne

    2009-03-01

    We describe the molecular-beam epitaxial (MBE) growth and fabrication of III-V metal-oxide-semiconductor (MOS) devices on Ge/Si virtual substrates. We show that high-temperature in-situ H 2 annealing in the chemical-vapor deposition system changes the Ge surface configuration and produces a surface with predominantly double-step-layer conditions, which is crucial for the growth of single-domain GaAs. In addition, the surface morphology of III-V on Ge/Si improved significantly with an annealing treatment of the Ge surface carried out under high arsenic background pressure in the MBE chamber. This facilitates uniform As-monolayer formation on the entire Ge surface. Low-temperature migration-enhanced epitaxy (MEE) and low-temperature conventional GaAs growth not only enhance the growth of single-domain GaAs without Ge outdiffusion but also produce a sufficiently smooth surface for high-k dielectric deposition, achieving low leakage current. A 300-nm-thick GaAs buffer layer was grown, followed by a 10 nm growth of In 0.2Ga 0.8As high-mobility channel layer. A 7-8-nm-thick Al 2O 3 layer was deposited ex-situ by atomic-layer deposition (ALD). We verify the quality of III-V growth using transmission electron microscopy (TEM), X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS) and photoluminescence (PL) measurement. The C-V characteristics show unpinning of the Fermi level, which is a necessary condition for gate voltage control of the drain current. This work suggests this materials combination is a promising candidate for the realization of advanced, nonclassical complementary-MOS and optoelectronic devices on Si substrates.

  3. Single Value Devices

    NARCIS (Netherlands)

    Mader, Angelika H.; Dertien, Edwin Christian; Reidsma, Dennis

    2011-01-01

    We live in a world of continuous information overflow, but the quality of information and communication is suffering. Single value devices contribute to the information and communication quality by fo- cussing on one explicit, relevant piece of information. The information is decoupled from a

  4. Single Value Devices

    NARCIS (Netherlands)

    Mader, Angelika H.; Dertien, Edwin Christian; Reidsma, Dennis; Camurri, Antonio; Costa, Cristina

    We live in a world of continuous information overflow, but the quality of information and communication is suffering. Single value devices contribute to information and communication quality by focussing on one explicit, relevant piece of information. The information is decoupled from a computer and

  5. Single Value Devices

    NARCIS (Netherlands)

    Mader, Angelika H.; Reidsma, Dennis; Dertien, Edwin Christian; Volpe, G; Kolkmeier, Jan; Camurri, A.; Kolkmeier, Jan; Nijholt, Antinus

    2015-01-01

    We live in a world of continuous information overflow, but the quality of information and communication is suffering. Single value devices contribute to the information and communication quality by focussing on one explicit, relevant piece of information. The information is decoupled from a computer

  6. Quality of life and functional capacity outcomes in the MOMENTUM 3 trial at 6 months: A call for new metrics for left ventricular assist device patients.

    Science.gov (United States)

    Cowger, Jennifer A; Naka, Yoshifumi; Aaronson, Keith D; Horstmanshof, Douglas; Gulati, Sanjeev; Rinde-Hoffman, Debbie; Pinney, Sean; Adatya, Sirtaz; Farrar, David J; Jorde, Ulrich P

    2018-01-01

    The Multicenter Study of MAGLEV Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) clinical trial demonstrated improved 6-month event-free survival, but a detailed analysis of health-related quality of life (HR-QOL) and functional capacity (FC) was not presented. Further, the effect of early serious adverse events (SAEs) on these metrics and on the general ability to live well while supported with a left ventricular assist system (LVAS) warrants evaluation. FC (New York Heart Association [NYHA] and 6-minute walk test [6MWT]) and HR-QOL (European Quality of Life [EQ-5D-5L] and the Kansas City Cardiomyopathy [KCCQ]) assessments were obtained at baseline and 6 months after HeartMate 3 (HM3, n = 151; Abbott, Abbott Park, IL) or HeartMate II (HMII, n = 138; Abbott) implant as part of the MOMENTUM 3 clinical trial. Metrics were compared between devices and in those with and without events. The proportion of patients "living well on an LVAS" at 6 months, defined as alive with satisfactory FC (NYHA I/II or 6MWT > 300 meters) and HR-QOL (overall KCCQ > 50), was evaluated. Although the median (25th-75th percentile) patient KCCQ (change for HM3: +28 [10-46]; HMII: +29 [9-48]) and EQ-5D-5L (change for HM3: -1 [-5 to 0]; HMII: -2 [-6 to 0]) scores improved from baseline to 6 months (p 0.05). Likewise, there was an equivalent improvement in 6MWT distance at 6 months in HM3 (+94 [1-274] meters] and HMII (+188[43-340 meters]) from baseline. In patients with SAEs (n = 188), 6MWTs increased from baseline (p metrics did not change. The development of left ventricular assist device-specific HR-QOL tools is needed to better characterize the effect of SAEs on a patient's well-being. MOMENTUM 3 clinical trial #NCT02224755. Copyright © 2018 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  7. High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

    International Nuclear Information System (INIS)

    Qiao Guiying; Jing Tianfu; Wang Nan; Gao Yuwei; Zhao Xin; Zhou Jifeng; Wang Wei

    2005-01-01

    The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co 2+ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co 2+ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co 2+ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits

  8. Nanocrystalline zeolite beta and zeolite Y as catalysts in used palm oil cracking for the production of biofuel

    Science.gov (United States)

    Taufiqurrahmi, Niken; Mohamed, Abdul Rahman; Bhatia, Subhash

    2011-08-01

    Nanocrystalline zeolites with crystal size smaller than 100 nm are potential replacement for conventional zeolite catalysts due to their unique characteristics and advantages. In this study, the synthesis of nanocrystalline zeolite Y (FAU) and nanocrystalline zeolite beta (BEA) under hydrothermal conditions is reported. The effect of crystal size on the physico-chemical characteristics of the zeolite, Y (FAU), and beta (BEA) is reported. The properties of nanocrystalline zeolites Y and Beta with crystal size around 50 nm are compared with the microcrystalline zeolite Y and microcrystalline zeolite beta, respectively. The performance of the nanocrystalline zeolite as a catalyst was investigated in the cracking of used palm oil for the production of biofuel. The nanocrystalline zeolite catalytic activity was compared with the activity of microcrystalline zeolite in order to study the effect of crystal size on the catalytic activity. Both nanocrystalline zeolites gave better performance in terms of conversion of used palm oil as well as selectivity for the formation of gasoline fraction. The increase in surface area and improved accessibility of the reactant in nanocrystalline zeolites enhanced the cracking activity as well as the desired product selectivity.

  9. A simple quality assurance test tool for the visual verification of light and radiation field congruent using electronic portal images device and computed radiography

    Directory of Open Access Journals (Sweden)

    Njeh Christopher F

    2012-03-01

    Full Text Available Abstract Background The radiation field on most megavoltage radiation therapy units are shown by a light field projected through the collimator by a light source mounted inside the collimator. The light field is traditionally used for patient alignment. Hence it is imperative that the light field is congruent with the radiation field. Method A simple quality assurance tool has been designed for rapid and simple test of the light field and radiation field using electronic portal images device (EPID or computed radiography (CR. We tested this QA tool using Varian PortalVision and Elekta iViewGT EPID systems and Kodak CR system. Results Both the single and double exposure techniques were evaluated, with double exposure technique providing a better visualization of the light-radiation field markers. The light and radiation congruency could be detected within 1 mm. This will satisfy the American Association of Physicists in Medicine task group report number 142 recommendation of 2 mm tolerance. Conclusion The QA tool can be used with either an EPID or CR to provide a simple and rapid method to verify light and radiation field congruence.

  10. Characterization of a test device for determination of the half value layer and of filtration with quality equity of materials in accordance with standard ABNT NBR IEC 60601-1-3

    International Nuclear Information System (INIS)

    Viana, Vlamir

    2012-01-01

    The motivation of this work was the development and validation of a device to perform the tests established by ABNT NBR IEC 60601-1-3 versions published in 2001 and 2011. The purpose of the tests is to determine the half-value layer – HVL and filtration with equivalent filtration quality in mmAl, materials that intercept the X-ray beam from their emission to the X-ray image receiving device. This filtration includes all the materials present in radiation source assembly, formed by the x-ray tube housing with x-ray tube inserted, the collimator (inherent filtration) and by materials present in the patients support, as Table and wall bucky, both incorporate image receiving device which is also evaluated. In the development was taken in consideration the routine of tests execution routine, in order to reduce the operator interaction with the system and in order to reduce the human factor in the execution, reflecting directly on the measurement uncertainty, in the runtime reduction of the runtime and radiation safety. The device was validated with respect to: a) Effect of positioning and distribution of the filters in the filter changer device; b) Influence of purity of the aluminum filter used in the device, and c) Comparison tests carried out with the testing device with respect to the tests carried out with a reference X-ray generator. (author)

  11. Sputtered tungsten-based ternary and quaternary layers for nanocrystalline diamond deposition.

    Science.gov (United States)

    Walock, Michael J; Rahil, Issam; Zou, Yujiao; Imhoff, Luc; Catledge, Shane A; Nouveau, Corinne; Stanishevsky, Andrei V

    2012-06-01

    Many of today's demanding applications require thin-film coatings with high hardness, toughness, and thermal stability. In many cases, coating thickness in the range 2-20 microm and low surface roughness are required. Diamond films meet many of the stated requirements, but their crystalline nature leads to a high surface roughness. Nanocrystalline diamond offers a smoother surface, but significant surface modification of the substrate is necessary for successful nanocrystalline diamond deposition and adhesion. A hybrid hard and tough material may be required for either the desired applications, or as a basis for nanocrystalline diamond film growth. One possibility is a composite system based on carbides or nitrides. Many binary carbides and nitrides offer one or more mentioned properties. By combining these binary compounds in a ternary or quaternary nanocrystalline system, we can tailor the material for a desired combination of properties. Here, we describe the results on the structural and mechanical properties of the coating systems composed of tungsten-chromium-carbide and/or nitride. These WC-Cr-(N) coatings are deposited using magnetron sputtering. The growth of adherent nanocrystalline diamond films by microwave plasma chemical vapor deposition has been demonstrated on these coatings. The WC-Cr-(N) and WC-Cr-(N)-NCD coatings are characterized with atomic force microscopy and SEM, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation.

  12. Strain rate sensitivity of bulk multi-phase nanocrystalline Al-W-based alloy

    Science.gov (United States)

    Varam, Sreedevi; Narayana, P. V. S. L.; Prasad, Muvva D.; Chakravarty, D.; Rajulapati, Koteswararao V.; Bhanu Sankara Rao, K.

    2014-09-01

    High-energy ball milling of conventional coarse-grained aluminium and nanocrystalline W in an Al-10 at.%W composition results in the formation of a two-phase mixture of Al and W with nanocrystalline features. Subsequent compaction of these powders using spark plasma sintering (SPS) at 748 K resulted in the formation of an Al12W phase in the nanocrystalline aluminium matrix. It is suggested that the mere attainment of nanocrystallinity was not enough to trigger a reaction between Al and W to form Al12W but that sufficient thermal activation was also required, as supplied during SPS. The second-phase particles (~175 nm in size) are uniformly distributed in the nanocrystalline Al matrix having a grain size of ~40 nm. The nanocomposite possessed a high hardness of 5.42 ± 0.33 GPa and an elastic modulus of 145 ± 5 GPa, both measured using depth-sensing nanoindentation. At room temperature, this novel nanocomposite exhibited a strain rate sensitivity (SRS) of 0.024 ± 0.001 and an activation volume in the range of 3.78-3.88 b3. Interfacial regions, viz. grain boundaries and triple junctions in the matrix and the reinforcement, matrix/particle boundaries, etc. could be influential factors in deciding the SRS and the activation volume. A scanning probe microscope image of the nanoindent shows a plastic flow region around the periphery of the indent.

  13. Selective catalytic reduction of NO{sub 2} with urea in nanocrystalline NaY zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Gonghu Li; Conrad A. Jones; Vicki H. Grassian; Sarah C. Larsen [University of Iowa, Iowa City, IA (United States). Department of Chemistry

    2005-09-10

    In this study, the selective catalytic reduction (SCR) of NO{sub 2} with urea in nanocrystalline NaY zeolite was investigated with in situ transmission Fourier transform infrared (FTIR) spectroscopy and solid-state nuclear magnetic resonance spectroscopy. At T=473 K, the reaction rate for urea-SCR of NO{sub 2} in nanocrystalline NaY zeolite was significantly greater than that in commercial NaY zeolite with a larger crystal size. In addition, a dramatic decrease in the concentration of undesirable surface species, including biuret and cyanuric acid, was observed in nanocrystalline NaY compared with commercial NaY after urea-SCR of NO{sub 2} at T=473 K. The increased reactivity for urea-SCR of NO{sub 2} was attributed to silanol groups and extra-framework aluminum species located on the external surface of nanocrystalline NaY. Specifically, NOx storage as nitrate and nitrite on the internal zeolite surface was coupled to reactive deNOx sites on the external surface. Isotopic labeling combined with IR analysis suggest that NN bond formation involved both an N-atom originating from NO{sub 2} and an N-atom originating from urea. This is the first clear example demonstrating that the increased external surface area (up to 40% of total surface area) of nanocrystalline zeolites can be used as a reactive surface with unique active sites for catalysis.

  14. Effect of microscale shear stresses on the martensitic phase transformation of nanocrystalline tetragonal zirconia powders

    DEFF Research Database (Denmark)

    Skovgaard, Mette; Ahniyaz, Anwar; Sørensen, Bent F.

    2010-01-01

    For the first time, the effect of microscale shear stress induced by both mechanical compression and ball-milling on the phase stability of nanocrystalline tetragonal zirconia (t-ZrO2) powders was studied in water free, inert atmosphere. It was found that nanocrystalline t-ZrO2 powders are extrem......For the first time, the effect of microscale shear stress induced by both mechanical compression and ball-milling on the phase stability of nanocrystalline tetragonal zirconia (t-ZrO2) powders was studied in water free, inert atmosphere. It was found that nanocrystalline t-ZrO2 powders...... was observed. Ball-milling induced microscale stress has a similar effect on the t → m phase transformation. Furthermore, it was found that even very mild milling condition, such as 120 rpm, 1 h (0.5 mm balls) was enough to induce phase transformation. Surfactant assisted ball-milling was found to be very...... effective in de-agglomeration of our nanocrystalline porous ZrO2 particles into discrete nanocrystals. However, the t → m phase transformation could not be avoided totally even at very mild milling condition. This suggests that the metastable t-ZrO2 is extreme sensitive to microscale shear stress induced...

  15. High Pressure X-Ray Diffraction Studies of Nanocrystalline Materials

    Science.gov (United States)

    Palosz, B.; Stel'makh, S.; Grzanka, E.; Gierlotka, S.; Palosz, W.

    2004-01-01

    Experimental evidence obtained for a variety of nanocrystalline materials suggest that the crystallographic structure of a very small size particle deviates from that in the bulk crystals. In this paper we show the effect of the surface of nanocrystals on their structure by the analysis of generation and distribution of macro- and micro-strains at high pressures and their dependence on the grain size in nanocrystalline powders of Sic. We studied the structure of Sic nanocrystals by in-situ high-pressure powder diffraction technique using synchrotron and neutron sources and hydrostatic or isostatic pressure conditions. The diffraction measurements were done in HASYLAB at DESY using a Diamond Anvil Cell (DAC) in the energy dispersive geometry in the diffraction vector range up to 3.5 - 4/A and under pressures up to 50 GPa at room temperature. In-situ high pressure neutron diffraction measurements were done at LANSCE in Los Alamos National Laboratory using the HIPD and HIPPO diffractometers with the Paris-Edinburgh and TAP-98 cells, respectively, in the diffraction vector range up to 26 Examination of the response of the material to external stresses requires nonstandard methodology of the materials characterization and description. Although every diffraction pattern contains a complete information on macro- and micro-strains, a high pressure experiment can reveal only those factors which contribute to the characteristic diffraction patterns of the crystalline phases present in the sample. The elastic properties of powders with the grain size from several nm to micrometers were examined using three methodologies: (l), the analysis of positions and widths of individual Bragg reflections (used for calculating macro- and micro-strains generated during densification) [I], (2). the analysis of the dependence of the experimental apparent lattice parameter, alp, on the diffraction vector Q [2], and (3), the atomic Pair Distribution Function (PDF) technique [3]. The results

  16. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    Energy Technology Data Exchange (ETDEWEB)

    Dumpala, Ravikumar [Manufacturing Engineering Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Ramamoorthy, B. [Manufacturing Engineering Section, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Rao, M.S. Ramachandra, E-mail: msrrao@iitm.ac.in [Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-01-15

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings.

  17. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    Science.gov (United States)

    Dumpala, Ravikumar; Ramamoorthy, B.; Rao, M. S. Ramachandra

    2014-01-01

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings

  18. MEMS device for bending test: measurements of fatigue and creep of electroplated nickel

    DEFF Research Database (Denmark)

    Larsen, Kristian Pontoppidan; Rasmussen, Anette Alsted; Ravnkilde, Jan Tue

    2003-01-01

    In situ bending test devices with integrated electrostatic actuator were fabricated in electroplated nanocrystalline nickel. The device features approximately pure in-plane bending of the test beam. The excitation of the test beam has fixed displacement amplitude as the actuation electrodes...... are operated to pull-in. The device was fabricated with different lengths of the test beam ranging from 7 to 30 mum. Maximum stresses in the test beams were calculated to be ranging from 470 to 2100 MPa using finite element methods (FEM). Life tests were performed, where the development of the pull-in voltages...

  19. New approach to the synthesis of nanocrystalline boron carbide.

    Science.gov (United States)

    Herth, Simone; Joost, William J; Doremus, Robert H; Siegel, Richard W

    2006-04-01

    The use of nanoparticles in ceramic matrix composites provides lower sintering temperatures and higher densities at a given temperature than common coarse-grained materials. Nanocrystalline B4C was synthesized by an inexpensive carbothermal reduction method using carbon black and B2O3 as precursor. Full conversion was achieved at 1623 K for annealing times of 480 minutes or with a large excess of B2O3 and oxidation of the remaining carbon after 30 minutes of annealing. The average particle size of the synthesized B4C powder was 260 nm, which was reduced to 70 nm after separation of the small particle fraction from the larger particles by sedimentation. A mixture of the as-prepared powder and commercial coarse-grained B4C yielded an increase of the density of low temperature hot pressed samples by 25% in comparison to pure commercial B4C. Possible chemical reactions and mechanisms in the synthesis of B4C were examined with the Gibbs free energies of reactions. The most likely reaction was the reduction of B2O3 vapor at the surfaces of the carbon particles after its vapor transport from the liquid B2O3. An observed reduction of B4C yield above 1623 K was probably caused by loss of B2O3 vapor from the reaction mixture.

  20. Rheology and microstructure of aqueous suspensions of nanocrystalline cellulose rods.

    Science.gov (United States)

    Xu, Yuan; Atrens, Aleks D; Stokes, Jason R

    2017-06-15

    Nanocrystalline cellulose (NCC) is a negatively charged rod-like colloid obtained from the hydrolysis of plant material. It is thus expected that NCC suspensions display a rich set of phase behaviour with salt and pH because of its anisotropic shape and electrical double layer that gives rise to liquid crystallinity and self-assembly respectively. It should thus be possible to tune the rheological properties of NCC suspensions for a wide variety of end-use applications. Rheology and structural analysis techniques are used to characterise surface-sulphated NCC suspensions as a function of pH, salinity (NaCl) and NCC concentration. Structural techniques include atomic force microscopy, Zeta potential, dynamic light scattering, and scanning electron microscopy. A phase diagram is developed based on the structure-rheology measurements showing various states of NCC that form as a function of salt and NCC concentration, which go well beyond those previously reported. This extended range of conditions reveals regions where the suspension is a viscous fluid and viscoelastic soft solid, as well as regions of instability that is suggested to arise when there is sufficient salt to reduce the electrical double layer (as explained qualitatively using DLVO theory) but insufficient NCC to form a load bearing network. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Boron Doped Nanocrystalline Diamond Films for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    V. Petrák

    2011-01-01

    Full Text Available With the rise of antibiotic resistance of pathogenic bacteria there is an increased demand for monitoring the functionality of bacteria membranes, the disruption of which can be induced by peptide-lipid interactions. In this work we attempt to construct and disrupt supported lipid membranes (SLB on boron doped nanocrystalline diamond (B-NCD. Electrochemical Impedance Spectroscopy (EIS was used to study in situ changes related to lipid membrane formation and disruption by peptide-induced interactions. The observed impedance changes were minimal for oxidized B-NCD samples, but were still detectable in the low frequency part of the spectra. The sensitivity for the detection of membrane formation and disruption was significantly higher for hydrogenated B-NCD surfaces. Data modeling indicates large changes in the electrical charge when an electrical double layer is formed at the B-NCD/SLB interface, governed by ion absorption. By contrast, for oxidized B-NCD surfaces, these changes are negligible indicating little or no change in the surface band bending profile.

  2. Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

    Science.gov (United States)

    Pareta, Rajesh; Yang, Lei; Kothari, Abhishek; Sirinrath, Sirivisoot; Xiao, Xingcheng; Sheldon, Brian W; Webster, Thomas J

    2010-10-01

    Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes diamond and, thus, should be further studied for improving orthopedic applications. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  3. Application of printed nanocrystalline diamond film for electron emission cathode

    International Nuclear Information System (INIS)

    Zhang Xiuxia; Wei Shuyi; Lei Chongmin; Wei Jie; Lu Bingheng; Ding Yucheng; Zhu Changchun

    2011-01-01

    The low-cost and large area screen-printed nano-diamond film (NDF) for electronic emission was fabricated. The edges and corners of nanocrystalline diamond are natural field-emitters. The nano-diamond paste for screen-printing was fabricated of mixing nano-graphite and other inorganic or organic vehicles. Through enough disperse in isopropyl alcohol by ultrasonic nano-diamond paste was screen-printed on the substrates to form NDF. SEM images showed that the surface morphology of NDF was improved, and the nano-diamond emitters were exposed from NDF through the special thermal-sintering technique and post-treatment process. The field emission characteristics of NDF were measured under all conditions with 10 -6 Pa pressure. The results indicated that the field emission stability and emission uniformity of NDF were improved through hydrogen plasma post-treatment process. The turn-on field decreased from 1.60 V/μm to 1.25 V/μm. The screen-printed NDF can be applied to the displays electronic emission cathode for low-cost outdoor in large area.

  4. Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films

    International Nuclear Information System (INIS)

    Amin-Ahmadi, Behnam; Connétable, Damien; Fivel, Marc; Tanguy, Döme; Delmelle, Renaud; Turner, Stuart; Malet, Loic; Godet, Stephane; Pardoen, Thomas; Proost, Joris; Schryvers, Dominique

    2016-01-01

    The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.

  5. F-centre luminescence in nanocrystalline CeO2

    International Nuclear Information System (INIS)

    Aškrabić, S; Dohčević-Mitrović, Z D; Araújo, V D; Ionita, G; De Lima, M M Jr; Cantarero, A

    2013-01-01

    Nanocrystalline CeO 2 powders were synthesized by two cost-effective methods: the self-propagating room temperature (SPRT) method and the precipitation method. Differently prepared samples exhibited different temperature-dependent photoluminescence (PL) in the ultraviolet and visible regions. The PL signals originated from different kinds of oxygen-deficient defect centres with or without trapped electrons (F 0 , F + or F ++ centres). The temperature-dependent PL spectra were measured using different excitation lines, below (457, 488 and 514 nm) or comparable (325 nm) to the ceria optical band gap energy, in order to investigate the positions of intragap localized defect states. Evidence for the presence of F + centres was supported by the signals observed in electron paramagnetic resonance (EPR) measurements. Based on PL and EPR measurements it was shown that F + centres dominate in the CeO 2 sample synthesized by the SPRT method, whereas F 0 centres are the major defects in the CeO 2 sample synthesized by the precipitation method. The luminescence from F ++ states, as shallow trap states, was registered in both samples. Energy level positions of these defect states in the ceria band gap were proposed. (paper)

  6. F-centre luminescence in nanocrystalline CeO2

    Science.gov (United States)

    Aškrabić, S.; Dohčević-Mitrović, Z. D.; Araújo, V. D.; Ionita, G.; de Lima, M. M., Jr.; Cantarero, A.

    2013-12-01

    Nanocrystalline CeO2 powders were synthesized by two cost-effective methods: the self-propagating room temperature (SPRT) method and the precipitation method. Differently prepared samples exhibited different temperature-dependent photoluminescence (PL) in the ultraviolet and visible regions. The PL signals originated from different kinds of oxygen-deficient defect centres with or without trapped electrons (F0, F+ or F++ centres). The temperature-dependent PL spectra were measured using different excitation lines, below (457, 488 and 514 nm) or comparable (325 nm) to the ceria optical band gap energy, in order to investigate the positions of intragap localized defect states. Evidence for the presence of F+ centres was supported by the signals observed in electron paramagnetic resonance (EPR) measurements. Based on PL and EPR measurements it was shown that F+ centres dominate in the CeO2 sample synthesized by the SPRT method, whereas F0 centres are the major defects in the CeO2 sample synthesized by the precipitation method. The luminescence from F++ states, as shallow trap states, was registered in both samples. Energy level positions of these defect states in the ceria band gap were proposed.

  7. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    Science.gov (United States)

    Sherly, K. B.; Rakesh, K.

    2014-01-01

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl2ṡ8H2O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  8. Grain Growth in Nanocrystalline Mg-Al Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kruska, Karen; Rohatgi, Aashish; Vemuri, Venkata Rama Ses; Kovarik, Libor; Moser, Trevor H.; Evans, James E.; Browning, Nigel D.

    2017-10-05

    An improved understanding of grain growth kinetics in nanocrystalline materials, and in metals and alloys in general, is of continuing interest to the scientific community. In this study, Mg - Al thin films containing ~10 wt.% Al and with 14.5 nm average grain size were produced by magnetron-sputtering and subjected to heat-treatments. The grain growth evolution in the early stages of heat treatment at 423 K (150 °C), 473 K (200 °C) and 573K (300 °C) was observed with transmission electron microscopy and analyzed based upon the classical equation developed by Burke and Turnbull. The grain growth exponent was found to be 7±2 and the activation energy for grain growth was 31.1±13.4 kJ/mol, the latter being significantly lower than in bulk Mg-Al alloys. The observed grain growth kinetics are explained by the Al supersaturation in the matrix and the pinning effects of the rapidly forming beta precipitates and possibly shallow grain boundary grooves. The low activation energy is attributed to the rapid surface diffusion which is dominant in thin film systems.

  9. Functional supramolecular ruthenium cyclodextrin dyes for nanocrystalline solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Faiz, J.; Pikramenou, Z. [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Philippopoulos, A.I.; Kontos, A.G.; Falaras, P. [NCSR ' ' Demokritos' ' , Institute of Physical Chemistry, Aghia Paraskevi Atiikis, 15310, Athens (Greece)

    2007-01-05

    A supramolecular complex [Ru(dcb){sub 2}({alpha}-CD-5-bpy)]Cl{sub 2} (1-{alpha}-CD) (dcb = 4,4'-dicarboxyl-2,2'-bipyridine, {alpha}-CD-5-bpy = 6-mono[5-methyl(5'-methyl-2,2'-bipyridyl)]-permethylated {alpha}-CD) (CD: cyclodextrin) based on a ruthenium tris-bipyridyl core with an appended {alpha}-CD cavity is designed and synthesised, in order to facilitate dye/redox couple interaction and dye regeneration in nanocrystalline TiO{sub 2} solar cells. The luminescent complex is fully characterized and anchored on mesoporous titania electrodes showing increased power-conversion efficiency in solid-state dye-sensitized solar cells using a composite polymer electrolyte. Direct comparison of the properties of the CD complex with an analogous ruthenium complex [Ru(dcb){sub 2}(5,5'-dmbpy)]Cl{sub 2} (2) (5,5'-dmbpy = 5,5'-dimethylbipyridine) without the CD cavity reveals that the photovoltaic performance of 1-{alpha}-CD is enhanced by about 40 % compared to 2. Independent studies have shown complexation of the iodide redox couple to the CD in 1-{alpha}-CD. These results indicate that the CD moiety is able to act as a mediator and fine tune the photoelectrode/electrolyte interface. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  10. Temperature Dependent Dielectric Behavior of Nanocrystalline Ca Ferrite

    Science.gov (United States)

    Samariya, Arvind; Pareek, S. P.; Sharma, P. K.; Prasad, Arun S.; Dhawan, M. S.; Dolia, S. N.; Sharma, K. B.

    Dielectric behaviour of Nanocrystalline CaFe2O4 ferrite synthesized by advanced sol- gel method has been investigated as a function of frequency at different temperatures. Rietveld profile refinement of the XRD pattern confirms formation of cubic spinel structure of the specimen.The dispersion in dielectric behavior of CaFe2O4ferrite sample has been observed in the temperature range of 100-250˚C as a function of frequency in the range 75 kHz to 10 MHz Both the real value of dielectric constant (ɛ‧) and the dielectric loss factor (tanδ) decrease with frequency. This decrease in the values of ɛ‧ and tanδ could be explained on the basis of available ferrous, i.e. Fe2+, ions on octahedral sites such that beyond a certain frequency of applied electric field the electronic exchange between the ferrous and ferric ions i.e. Fe2+↔Fe3+ cannot follow the applied alternating electric field.

  11. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, K. B.; Rakesh, K. [Mahatma Gandhi University Regional Research Center in Chemistry, Department of Chemistry, Mar Athanasius College, Kothamangalam-686666, Kerala (India)

    2014-01-28

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}⋅8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  12. Production of nanocrystalline cellulose from lignocellulosic biomass: technology and applications.

    Science.gov (United States)

    Brinchi, L; Cotana, F; Fortunati, E; Kenny, J M

    2013-04-15

    The use of renewables materials for industrial applications is becoming impellent due to the increasing demand of alternatives to scarce and unrenewable petroleum supplies. In this regard, nanocrystalline cellulose, NCC, derived from cellulose, the most abundant biopolymer, is one of the most promising materials. NCC has unique features, interesting for the development of new materials: the abundance of the source cellulose, its renewability and environmentally benign nature, its mechanical properties and its nano-scaled dimensions open a wide range of possible properties to be discovered. One of the most promising uses of NCC is in polymer matrix nanocomposites, because it can provide a significant reinforcement. This review provides an overview on this emerging nanomaterial, focusing on extraction procedures, especially from lignocellulosic biomass, and on technological developments and applications of NCC-based materials. Challenges and future opportunities of NCC-based materials will be are discussed as well as obstacles remaining for their large use. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Ultrasound assisted synthesis of nanocrystalline zinc oxide: Experiments and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Hosni, Mongia [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Farhat, Samir, E-mail: farhat@lspm.cnrs.fr [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Schoenstein, Frederic; Karmous, Farah; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Viana, Bruno [LCMCP Chimie-Paristech, UPMC, Collège de France, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Mgaidi, Arbi [Laboratoire de chimie minérale industrielle université Tunis el Manar (Tunisia)

    2014-12-05

    Highlights: • ZnO nanospheres and nanowires were grown using ultrasound and thermal activation techniques. • The growth uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). • A thermochemical model was developed based on thermodynamic equilibrium calculations. • We estimate species distribution in the bubble in temperature range from 5000 K to ambient. • We propose a new mechanism for ZnO growth assisted by ultrasound irradiation. - Abstract: A fast and green approach is proposed for the preparation of nanocrystalline zinc oxide (ZnO) via ultrasonic (US) irradiation in polyol medium. The process uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). The protocol is compared to thermal activation under the same chemical environment. The activation method is found to be playing a critical role in the selective synthesis of morphologically distinct nanostructures. As compared to thermally activated conventional polyol process, (US) permits to considerably reduce reaction time as well as size of particles. In addition, the shape of these nanoparticles was changed from long nanowires to small nanospheres, indicating different reaction mechanisms. To explain this difference, a thermochemical model was developed based on thermodynamic equilibrium calculations. The model estimate species distribution in the bubble in temperature range from 5000 K to ambient simulating quenching process during bubble formation and collapse. Our results indicate the presence of high density of zinc atoms that could be responsible of a high density of nucleation as compared to thermal activation.

  14. Grain boundary resistance to amorphization of nanocrystalline silicon carbide

    Science.gov (United States)

    Chen, Dong; Gao, Fei; Liu, Bo

    2015-01-01

    Under the C displacement condition, we have used molecular dynamics simulation to examine the effects of grain boundaries (GBs) on the amorphization of nanocrystalline silicon carbide (nc-SiC) by point defect accumulation. The results show that the interstitials are preferentially absorbed and accumulated at GBs that provide the sinks for defect annihilation at low doses, but also driving force to initiate amorphization in the nc-SiC at higher doses. The majority of surviving defects are C interstitials, as either C-Si or C-C dumbbells. The concentration of defect clusters increases with increasing dose, and their distributions are mainly observed along the GBs. Especially these small clusters can subsequently coalesce and form amorphous domains at the GBs during the accumulation of carbon defects. A comparison between displacement amorphized nc-SiC and melt-quenched single crystal SiC shows the similar topological features. At a dose of 0.55 displacements per atom (dpa), the pair correlation function lacks long range order, demonstrating that the nc-SiC is fully amorphilized. PMID:26558694

  15. Optical Properties of ZnO-Alloyed Nanocrystalline Films

    Directory of Open Access Journals (Sweden)

    Hui Che

    2012-01-01

    Full Text Available ZnO is emerging as one of the materials of choice for UV applications. It has a deep excitonic energy level and a direct bandgap of ~3.4 eV. Alloying ZnO with certain atomic constituents adds new optical and electronic functionalities to ZnO. This paper presents research on MgxZn1−xO and ZnS1−xOx nanocrystalline flexible films, which enable tunable optical properties in the deep-UV and in the visible range. The ZnO and Mg0.3Zn0.7O films were found to have bandgaps at 3.35 and 4.02 eV, respectively. The photoluminescence of the Mg0.3Zn0.7O exhibited a bandedge emission at 3.95 eV, and at lower energy 3.38 eV due to the limited solubility inherent to these alloys. ZnS0.76O0.24 and ZnS0.16O0.84 were found to have bandgaps at 3.21 and 2.65 eV, respectively. The effect of nitrogen doping on ZnS0.16O0.84 is discussed in terms of the highly lattice mismatched nature of these alloys and the resulting valence-band modification.

  16. Nanocrystalline titanium characteristics obtained through cryogenic and high energy milling

    International Nuclear Information System (INIS)

    Rojas, P; Zuniga, A; Lavernia, E.J

    2008-01-01

    The microstructure and changes in chemical composition of Ti powders produced by cryogenic milling (modified Atritor) and by high energy milling (Spex mill) were investigated. The effect of high energy milling and cryomilling parameters, such as milling time and ball to powder ratio (BPR), on the particle size, grain size, chemistry, and structure of Ti powders were investigated using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The experimental results show that Ti powders with a grain size of approximately 20 nm (nanocrystalline) can be produced using the cryomilling technique. The average particle size increased initially with milling time from the original 55 μm to a maximum value of 125 after milling for 2 hours, and then decreased to 44μm after milling for 8 hours. Both the average particle size and the grain size decreased as the BPR increased. The results using Spex mill show that the particle size and grain size both decreased as the milling time increased. The oxygen, nitrogen and iron content of the powders increased with the milling time (au)

  17. Adsorption of Derivatized Dextran Polyelectrolytes onto Nanocrystalline Cellulose

    Science.gov (United States)

    Esker, Alan; Kittle, Joshua; Du, Xiaosong; Jiang, Feng; Roman, Maren; Wondraczek, Holger; Koschella, Andreas; Heinze, Thomas

    2012-02-01

    The adsorption of a series of cationically derivatized dextran polyelectrolytes onto anionic nanocrystalline cellulose (ANC) has been studied using quartz crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR). Samples of dimethylaminoethyl-dextran (DMAE-Dex), diethylaminoethyl-dextran (DEAE-Dex), and diisopropylaminoethyl-dextran (DIAE-Dex) had degrees of substitution (DS) ranging from 0.06-0.90. DMAE-Dex, DEAE-Dex, and DIAE-Dex all showed decreasing adsorption onto ANC and decreasing water content of the adsorbed film with increasing DS. Additionally, DEAE-Dex films adsorbed onto ANC had lower water contents than DMAE-Dex films with the same DS. Interestingly, QCM-D results for DIAE-Dex with high DS revealed mass loss, while SPR results clearly showed DIAE-Dex adsorbed onto ANC. These observations were consistent with dehydration of the ANC substrate. This study indicates that by controlling the DS and hydrophobic content of the polyelectrolyte, the water content of the film can be tailored.

  18. The modified nanocrystalline cellulose for hydrophobic drug delivery

    International Nuclear Information System (INIS)

    Qing, Weixia; Wang, Yong; Wang, Youyou; Zhao, Dongbao; Liu, Xiuhua; Zhu, Jinhua

    2016-01-01

    Graphical abstract: - Highlights: • Torispherical NCC was synthesized through the improvements on the hydrolysis method. • NCC was firstly modified with CTMAB as a drug carrier. • Luteolin and luteoloside loading CTMAB-coated NCC were studied. - Abstract: In this work, torispherical nanocrystalline cellulose (NCC) was synthesized, and firstly modified with a cationic surfactant cetyltrimethylammonium bromide (CTMAB). It was proved that the kinetics of NCC adsorbing CTMAB followed the pseudo-second-order kinetics equation, and the adsorption isotherm model followed Freundlich which was multi molecular layer adsorption model. The morphology and structure of NCC and CTMAB-coated NCC were characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Stabilities of NCC and CTMAB-coated NCC were assayed by zeta potential. The results showed that NCC in CTMAB solution was well-dispersed and stable. Moreover, the drug loading and release performance of CTMAB-coated NCC were studied using luteolin (LUT) and luteoloside (LUS) as model drugs.

  19. Ultrasound assisted synthesis of nanocrystalline zinc oxide: Experiments and modelling

    International Nuclear Information System (INIS)

    Hosni, Mongia; Farhat, Samir; Schoenstein, Frederic; Karmous, Farah; Jouini, Noureddine; Viana, Bruno; Mgaidi, Arbi

    2014-01-01

    Highlights: • ZnO nanospheres and nanowires were grown using ultrasound and thermal activation techniques. • The growth uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). • A thermochemical model was developed based on thermodynamic equilibrium calculations. • We estimate species distribution in the bubble in temperature range from 5000 K to ambient. • We propose a new mechanism for ZnO growth assisted by ultrasound irradiation. - Abstract: A fast and green approach is proposed for the preparation of nanocrystalline zinc oxide (ZnO) via ultrasonic (US) irradiation in polyol medium. The process uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). The protocol is compared to thermal activation under the same chemical environment. The activation method is found to be playing a critical role in the selective synthesis of morphologically distinct nanostructures. As compared to thermally activated conventional polyol process, (US) permits to considerably reduce reaction time as well as size of particles. In addition, the shape of these nanoparticles was changed from long nanowires to small nanospheres, indicating different reaction mechanisms. To explain this difference, a thermochemical model was developed based on thermodynamic equilibrium calculations. The model estimate species distribution in the bubble in temperature range from 5000 K to ambient simulating quenching process during bubble formation and collapse. Our results indicate the presence of high density of zinc atoms that could be responsible of a high density of nucleation as compared to thermal activation

  20. Ultra-nanocrystalline diamond nanowires with enhanced electrochemical properties

    International Nuclear Information System (INIS)

    Shalini, Jayakumar; Lin, Yi-Chieh; Chang, Ting-Hsun; Sankaran, Kamatchi Jothiramalingam; Chen, Huang-Chin; Lin, I.-Nan; Lee, Chi-Young; Tai, Nyan-Hwa

    2013-01-01

    The effects of N 2 incorporation in Ar/CH 4 plasma on the electrochemical properties and microstructure of ultra-nanocrystalline diamond (UNCD) films are reported. While the electrical conductivity of the films increased monotonously with increasing N 2 content (up to 25%) in the plasma, the electrochemical behavior was optimized for UNCD films grown in (Ar–10% N 2 )/CH 4 plasma. Transmission electron microscopy showed that the main factor resulting in high conductivity in the films was the formation of needle-like nanodiamond grains and the induction graphite layer encapsulating these grains. The electrochemical process for N 2 -incorporated UNCD films can readily be activated due to the presence of nanographite along the grain boundaries of the films. The formation of needle-like diamond grains was presumably due to the presence of CN species that adhered to the existing nanodiamond clusters, which suppressed radial growth of the nanodiamond crystals, promoting anisotropic growth and the formation of needle-like nanodiamond. The N 2 -incorporated UNCD films outperformed other electrochemical electrode materials, such as boron-doped diamond and glassy carbon, in that the UNCD electrodes could sense dopamine, urea, and ascorbic acid simultaneously in the same mixture with clear resolution

  1. Understanding and controlling low-temperature aging of nanocrystalline materials.

    Energy Technology Data Exchange (ETDEWEB)

    Battaile, Corbett Chandler; Boyce, Brad Lee; Brons, Justin G.; Foiles, Stephen Martin; Hattar, Khalid Mikhiel; Holm, Elizabeth A; Padilla, Henry A.,; Sharon, John Anthony; Thompson, Gregory B.

    2013-10-01

    Nanocrystalline copper lms were created by both repetitive high-energy pulsed power, to produce material without internal nanotwins; and pulsed laser deposition, to produce nan- otwins. Samples of these lms were indented at ambient (298K) and cryogenic temperatures by immersion in liquid nitrogen (77K) and helium (4K). The indented samples were sectioned through the indented regions and imaged in a scanning electron microscope. Extensive grain growth was observed in the lms that contained nanotwins and were indented cryogenically. The lms that either lacked twins, or were indented under ambient conditions, were found to exhibit no substantial grain growth by visual inspection. Precession transmission elec- tron microscopy was used to con rm these ndings quantitatively, and show that 3 and 7 boundaries proliferate during grain growth, implying that these interface types play a key role in governing the extensive grain growth observed here. Molecular dynamics sim- ulations of the motion of individual grain boundaries demonstrate that speci c classes of boundaries - notably 3 and 7 - exhibit anti- or a-thermal migration, meaning that their mobilities either increase or do not change signi cantly with decreasing temperature. An in-situ cryogenic indentation capability was developed and implemented in a transmission electron microscope. Preliminary results do not show extensive cryogenic grain growth in indented copper lms. This discrepancy could arise from the signi cant di erences in con g- uration and loading of the specimen between the two approaches, and further research and development of this capability is needed.

  2. Modeling and simulation of boron-doped nanocrystalline silicon carbide thin film by a field theory.

    Science.gov (United States)

    Xiong, Liming; Chen, Youping; Lee, James D

    2009-02-01

    This paper presents the application of a multiscale field theory in modeling and simulation of boron-doped nanocrystalline silicon carbide (B-SiC). The multiscale field theory was briefly introduced. Based on the field theory, numerical simulations show that intergranular glassy amorphous films (IGFs) and nano-sized pores exist in triple junctions of the grains for nanocrystalline B-SiC. Residual tensile stress in the SiC grains and compressive stress on the grain boundaries (GBs) were observed. Under tensile loading, it has been found that mechanical response of 5 wt% boron-SiC exhibits five characteristic regimes. Deformation mechanism at atomic scale has been revealed. Tensile strength and Young's modulus of nanocrystalline SiC were accurately reproduced.

  3. Low-temperature magnetic behaviour in amorphous and nanocrystalline Fe-Nb-B alloys

    International Nuclear Information System (INIS)

    Skorvanek, I.; Duhaj, P.; Groessinger, R.

    2000-01-01

    The low-temperature magnetic behaviour is studied in a series of heat-treated amorphous and nanocrystalline Fe 80.5 Nb 7 B 12.5 samples with different volume fractions of crystalline phase. The measurements of coercivity, initial susceptibility and magnetostriction have been performed in a temperature range between 1.5 and 300 K. The coercivity of nanocrystalline samples shows a minimum versus measuring temperature. The temperature of this minimum is shifted to lower temperatures with an increasing volume fraction of crystalline phase. A significant magnetic hardening characterized by abrupt upturn of coercivity is reported for all nanocrystalline samples in the temperature range below 30 K. The role of different factors in determining the low-temperature magnetic behaviour is discussed

  4. Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

    Directory of Open Access Journals (Sweden)

    O. M. Lemine

    2014-01-01

    Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

  5. Formation of nanocrystalline TiC from titanium and different carbon sources by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Jia Haoling [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China); Zhang Zhonghua [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China)], E-mail: zh_zhang@sdu.edu.cn; Qi Zhen [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China); Liu Guodong [School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China); Bian Xiufang [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China)

    2009-03-20

    In this paper, the formation of nanocrystalline TiC from titanium powders and different carbon resources by mechanical alloying (MA) has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results show that nanocrystalline TiC can be synthesized from Ti powders and different carbon resources (activated carbon, carbon fibres or carbon nanotubes) by MA at room temperature. Titanium and different carbon resources have a significant effect on the Ti-C reaction and the formation of TiC during MA. Moreover, the formation of nanocrystalline TiC is governed by a gradual diffusion reaction mechanism during MA, regardless of different carbon resources.

  6. High-pressure X-ray diffraction study of bulk- and nanocrystalline GaN

    DEFF Research Database (Denmark)

    Jorgensen, J.E.; Jakobsen, J.M.; Jiang, Jianzhong

    2003-01-01

    Bulk- and nanocrystalline GaN have been studied by high-pressure energy-dispersive X-ray diffraction. Pressure-induced structural phase transitions from the wurtzite to the NaCl phase were observed in both materials. The transition pressure was found to be 40 GPa for the bulk-crystalline GaN, while...... the wurtzite phase was retained up to 60 GPa in the case of nanocrystalline GaN. The bulk moduli for the wurtzite phases were determined to be 187 ( 7) and 319 ( 10) GPa for the bulk- and nanocrystalline phases, respectively, while the respective NaCl phases were found to have very similar bulk moduli [ 208...... ( 28) and 206 ( 44) GPa]....

  7. Direct separation of short range order in intermixed nanocrystalline and amorphous phases

    International Nuclear Information System (INIS)

    Frenkel, Anatoly I.; Kolobov, Alexander V.; Robinson, Ian K.; Cross, Julie O.; Maeda, Yoshihito; Bouldin, Charles E.

    2002-01-01

    Diffraction anomalous fine-structure (DAFS) and extended x-ray absorption fine-structure (EXAFS) measurements were combined to determine short range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases of germanium. EXAFS yields information about the SRO of all Ge atoms in the sample, while DAFS determines the SRO of only the ordered fraction. We determine that the first-shell distance distribution is bimodal; the nanocrystalline distance is the same as the bulk crystal, to within 0.01(2) A ring , but the mean amorphous Ge-Ge bond length is expanded by 0.076(19) Angstrom. This approach can be applied to many systems of mixed amorphous and nanocrystalline phases

  8. THE LATTICE PARAMETERS AND RESIDUAL STRESSES IN BULK NANOCRYSTALLINE AND ULTRAFINE-GRAINED TITANIUM

    Directory of Open Access Journals (Sweden)

    Yu. M. Plotnikova

    2017-05-01

    Full Text Available Lattice parameters and residual stresses in the bulk nanocrystalline/ultrafine-grained titanium were studied by X-ray diffraction methods. The investigated samples were prepared using the method of the cryomechanical grain structure fragmentation with multiple rolling at the temperature of liquid nitrogen to the true strain value |e| = 3. Phasic change of the a and c parameters has been found with increasing degree of cryoreduction. This change was stronger for the parameter a. The observed change parameters associated with a relative slip and twinning activity (initial cryo-reduction stage as well as the formation of the nanocrystalline state (at higher degree of deformation. The most likely source of residual stresses arising in titanium at cryorolling is heterogeneous plastic deformation. The production of nanocrystalline / ultrafine-grained titanium using cryomechanical grain fragmentation method is accompanied by the formation of uniform compressive residual stresses in the informative deformable layer of billet.

  9. Synthesis of Mesoporous Nanocrystalline Zirconia by Surfactant-Assisted Hydrothermal Approach.

    Science.gov (United States)

    Nath, Soumav; Biswas, Ashik; Kour, Prachi P; Sarma, Loka S; Sur, Ujjal Kumar; Ankamwar, Balaprasad G

    2018-08-01

    In this paper, we have reported the chemical synthesis of thermally stable mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted hydrothermal approach. We have employed different type of surfactants such as CTAB, SDS and Triton X-100 in our synthesis. The synthesized nanocrystalline zirconia multistructures exhibit various morphologies such as rod, mortar-pestle with different particle sizes. We have characterized the zirconia multistructures by X-ray diffraction study, Field emission scanning electron microscopy, Attenuated total refection infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The thermal stability of as synthesized zirconia multistructures was studied by thermo gravimetric analysis, which shows the high thermal stability of nanocrystalline zirconia around 900 °C temperature.

  10. Microstructure characterization of nanocrystalline TiC synthesized by mechanical alloying

    International Nuclear Information System (INIS)

    Ghosh, B.; Pradhan, S.K.

    2010-01-01

    Nanocrystalline TiC is produced by mechanical milling the stoichiometric mixture of α-Ti and graphite powders at room temperature under argon atmosphere within 35 min of milling through a self-propagating combustion reaction. Microstructure characterization of the unmilled and ball-milled samples was done by both X-ray diffraction and electron microscopy. It reveals the fact that initially graphite layers were oriented along and in the course of milling, thin graphite layers were distributed evenly among the grain boundaries of α-Ti particles. Both α-Ti and TiC lattices contain stacking faults of different kinds. The grain size distribution obtained from the Rietveld's method and electron microscopy studies ensure that nanocrystalline TiC particles with almost uniform size (∼13 nm) can be prepared by mechanical alloying technique. The result obtained from X-ray analysis corroborates well with the microstructure characterization of nanocrystalline TiC by electron microscopy.

  11. Effect of WC/Co coherency phase boundaries on Fracture toughness of the nanocrystalline cemented carbides

    Science.gov (United States)

    Xie, Hongxian; Song, Xiaoyan; Yin, Fuxing; Zhang, Yongguang

    2016-08-01

    The effect of coherency WC/Co phase boundaries on the fracture toughness of the nanocrystalline WC-Co cemented carbides is studied by MD simulation method. The simulation results show that the nanocrystalline WC-Co cemented carbides with coherency WC/Co phase boundaries has higher fracture toughness than that without coherency WC/Co phase boundaries. Moreover, the mechanism of why coherency WC/Co phase boundaries can improve the fracture toughness of the nanocrystalline cemented carbides is also investigated. It is found the fact that the separation energy of the coherent WC/Co phase boundary is larger than that of the incoherent WC/Co phase boundaries is the main reason for this excellent mechanical property.

  12. Concentration device

    DEFF Research Database (Denmark)

    2013-01-01

    A concentration device (2) for filter filtration concentration of particles (4) from a volume of a fluid (6). The concentration device (2) comprises a filter (8) configured to filter particles (4) of a predefined size in the volume of the fluid (6). The concentration device (2) comprises...

  13. Photovoltaic device

    Energy Technology Data Exchange (ETDEWEB)

    Reese, Jason A.; Keenihan, James R.; Gaston, Ryan S.; Kauffmann, Keith L.; Langmaid, Joseph A.; Lopez, Leonardo C.; Maak, Kevin D.; Mills, Michael E.; Ramesh, Narayan; Teli, Samar R.

    2015-09-01

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device (10) with a multilayered photovoltaic cell assembly (100) and a body portion (200) joined at an interface region (410) and including an intermediate layer (500), at least one interconnecting structural member (1500), relieving feature (2500), unique component geometry, or any combination thereof.

  14. Photovoltaic device

    Energy Technology Data Exchange (ETDEWEB)

    Reese, Jason A; Keenihan, James R; Gaston, Ryan S; Kauffmann, Keith L; Langmaid, Joseph A; Lopez, Leonardo; Maak, Kevin D; Mills, Michael E; Ramesh, Narayan; Teli, Samar R

    2017-03-21

    The present invention is premised upon an improved photovoltaic device ("PV device"), more particularly to an improved photovoltaic device with a multilayered photovoltaic cell assembly and a body portion joined at an interface region and including an intermediate layer, at least one interconnecting structural member, relieving feature, unique component geometry, or any combination thereof.

  15. Structural and microstructural characterizations of nanocrystalline hydroxyapatite synthesized by mechanical alloying.

    Science.gov (United States)

    Lala, S; Satpati, B; Kar, T; Pradhan, S K

    2013-07-01

    Single phase nanocrystalline hydroxyapatite (HAp) powder has been synthesized by mechanical alloying the stoichiometric mixture of CaCO3 and CaHPO4 powders in open air at room temperature, for the first time, within 2 h of milling. Nanocrystalline hexagonal single crystals are obtained by sintering of 2h milled sample at 500 °C. Structural and microstructural properties of as-milled and sintered powders are revealed from both the X-ray line profile analysis and transmission electron microscopy. Shape and lattice strain of nanocrystalline HAp particles are found to be anisotropic in nature. Particle size of HAp powder remains almost invariant up to 10h of milling and there is no significant growth of nanocrystalline HAp particles after sintering at 500 °C for 3 h. Changes in lattice volume and some primary bond lengths of as-milled and sintered are critically measured, which indicate that lattice imperfections introduced into the HAp lattice during ball milling have been reduced partially after sintering the powder at elevated temperatures. We could achieve ~96.7% of theoretical density of HAp within 3h by sintering the pellet of nanocrystalline powder at a lower temperature of 1000 °C. Vickers microhardness (VHN) of the uni-axially pressed (6.86 MPa) pellet of nanocrystalline HAp is 4.5 GPa at 100 gm load which is close to the VHN of bulk HAp sintered at higher temperature. The strain-hardening index (n) of the sintered pellet is found to be >2, indicating a further increase in microhardness value at higher load. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. An investigation into the room temperature mechanical properties of nanocrystalline austenitic stainless steels

    International Nuclear Information System (INIS)

    Eskandari, Mostafa; Zarei-Hanzaki, Abbas; Abedi, Hamid Reza

    2013-01-01

    Highlights: ► Strength of nanocrystalline specimens follows a trend of a remarkable rise along with a small drop in ductility in comparison to the coarse-grained one. ► Universal correlation of linear type (UTS = mτ max ) between shear punch test data and the tensile strength may be unreliable for the nanocrystalline materials. ► Actual relation between the maximum shear and ultimate tensile strength follows an empirical formula of UTS=0.013τ max 2 -25.62τ max +13049. -- Abstract: The present work has been conducted to evaluate the mechanical properties of nanostructured 316L and 301 austenitic stainless steels. The nanocrystalline structures were produced through martensite treatment which includes cold rolling followed by annealing treatment. The effect of equivalent rolling strain and annealing parameters on the room temperature mechanical behavior of the experimental alloys have been studied using the shear punch testing technique. The standard uniaxial tension tests were also carried out to adapt the related correlation factors. The microstructures and the volume fraction of phases were characterized by transmission electron microscopy and feritscopy methods, respectively. The results indicate that the strength of nanocrystalline specimens remarkably increases, but the ductility in comparison to the coarse-grained one slightly decreases. In addition the strength of nanocrystalline specimens has been increased by decreasing the annealing temperature and increasing the equivalent rolling strain. The analysis of the load–displacement data has also disclosed that the universal correlation of linear type (UTS = mτ max ) between shear punch test data and the tensile strength is somehow unreliable for the nanocrystalline materials. The results suggest that the actual relation between the maximum shear strength and ultimate tensile strength follows a second order equation of type UTS=aτ max 2 -bτ max +c.

  17. Dye-Sensitized Solar Cells Based on High Surface Area Nanocrystalline Zinc Oxide Spheres

    Directory of Open Access Journals (Sweden)

    Pavuluri Srinivasu

    2011-01-01

    Full Text Available High surface area nanocrystalline zinc oxide material is fabricated using mesoporous nanostructured carbon as a sacrificial template through combustion process. The resulting material is characterized by XRD, N2 adsorption, HR-SEM, and HR-TEM. The nitrogen adsorption measurement indicates that the materials possess BET specific surface area ca. 30 m2/g. Electron microscopy images prove that the zinc oxide spheres possess particle size in the range of 0.12 μm–0.17 μm. The nanocrystalline zinc oxide spheres show 1.0% of energy conversion efficiency for dye-sensitized solar cells.

  18. Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Levashov, Evgeny

    2015-01-01

    and nanoscale properties are discussed and compared. The examples of incorporation of peculiar nanocrystalline effects (like large content of amorphous or semi-amorphous grain boundary phase, partial dislocation GB emission/glide/GB absorption based deformation mechanism, diffusion deformation, etc.......) into the continuum mechanical approach are given. The possibilities of using micromechanical models to explore the ways of the improving the properties of nanocrystalline materials by modifying their structures (e.g., dispersion strengthening, creating non-equilibrium grain boundaries, varying the grain size...

  19. Structure and Optical Properties of Nanocrystalline Hafnium Oxide Thin Films (PostPrint)

    Science.gov (United States)

    2014-09-01

    AFRL-RX-WP-JA-2014-0214 STRUCTURE AND OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) Neil R. Murphy AFRL...OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...publication is available at http://dx.doi.org/10.1016/j.optmat.2014.08.005 14. ABSTRACT Hafnium oxide (HfO2) films were grown by sputter-deposition by

  20. In situ atomic-scale observation of irradiation induced carbon nanocrystalline formation from dense carbon clusters

    Science.gov (United States)

    Wang, Chengbing; Li, Zhengtong; Ling, San; Lei, Tao; Su, Jinbu

    2018-03-01

    We present a direct observation of the transformation of dense amorphous carbon clusters into diamond nanocrystalline under electron beam irradiation by in situ transmission electron microscopy, where the surrounding carbon matrix did not significantly change. Our findings provide clear and convincing evidence for the diamond nanocrystalline evolving from energetic amorphous carbon sites. Furthermore, graphitization of amorphous carbons usually demands a high temperature combined with high pressure. Hence, graphitization of amorphous carbons at relatively low temperatures is highly desired. Here we offer a useful method for catalyst-free graphitization of amorphous carbons by employing moderate electron beam irradiation, without external heating being applied.

  1. Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

    DEFF Research Database (Denmark)

    Schiøtz, Jakob; Vegge, Tejs; Di Tolla, Francesco

    1999-01-01

    that the main deformation mode is sliding in the grain boundaries through a large number of uncorrelated events, where a few atoms (or a few tens of atoms) slide with respect to each other. Little dislocation activity is seen in the grain interiors. The localization of the deformation to the grain boundaries......Nanocrystalline metals, i.e., metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the plastic behavior of nanocrystalline copper. The simulations show...

  2. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    Energy Technology Data Exchange (ETDEWEB)

    Herchko, S; Ding, G [Vanderbilt University, Nashville, TN (United States)

    2016-06-15

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  3. Device quality InO{sub x}:Sn and InO{sub x} thin films deposited at room temperature with different rf-power densities

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, A., E-mail: ana.de.amaral@ist.utl.pt [Dept. de Fisica and ICEMS, Instituto Superior Tecnico/Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Brogueira, P. [Dept. de Fisica and ICEMS, Instituto Superior Tecnico/Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Conde, O. [Universidade de Lisboa, Dept. de Fisica and ICEMS, Campo Grande, 1749-016 Lisboa (Portugal); Lavareda, G. [Dept. de Ciencia dos Materiais and CTS, FCT-UNL, 2829-516 Caparica (Portugal); Nunes de Carvalho, C. [Dept. de Ciencia dos Materiais, FCT-UNL and ICEMS, 2829-516 Caparica (Portugal)

    2012-12-30

    The influence of tin doping on the electrical, optical, structural and morphological properties of indium oxide films produced by radio-frequency plasma enhanced reactive thermal evaporation is studied, as transport properties are expected to improve with doping. Undoped and tin doped indium oxide thin films are deposited at room temperature using both pure In rods and (95-80) % In:(5-20) % Sn alloys as evaporation sources and 19.5 mW/cm{sup 2} and 58.6 mW/cm{sup 2} as rf-power densities. The two most important macroscopic properties - visible transparency and electrical resistivity - are relatively independent of tin content (0-20%). Visible transmittance of about 75% and electrical resistivity around 5 Multiplication-Sign 10{sup -4} {Omega}{center_dot}cm can be observed in the films. The structural features are similar for all samples. Nevertheless, the surface morphology characterization shows that the homogeneity of the films varies according to the tin content. Moreover this variation is a balance between the rf-power and the tin content in the alloy: i) films with small and compact grains are produced at 58.6 mW/cm{sup 2} from a 5% Sn alloy or at 19.5 mW/cm{sup 2} from a 15% Sn alloy and consequently, smooth surfaces with reduced roughness and similar grain size and shape are obtained; ii) films showing the presence of aggregates randomly distributed above a tissue formed of thinner grains and higher roughness are produced at the other deposition conditions. - Highlights: Black-Right-Pointing-Pointer InO{sub x}:Sn and InO{sub x} thin films were deposited at room temperature. Black-Right-Pointing-Pointer Transparency and electrical resistivity are relatively independent of Sn content. Black-Right-Pointing-Pointer Device quality material was obtained. Black-Right-Pointing-Pointer The surface morphology homogeneity of the films varies with tin content.

  4. Device quality InOx:Sn and InOx thin films deposited at room temperature with different rf-power densities

    International Nuclear Information System (INIS)

    Amaral, A.; Brogueira, P.; Conde, O.; Lavareda, G.; Nunes de Carvalho, C.

    2012-01-01

    The influence of tin doping on the electrical, optical, structural and morphological properties of indium oxide films produced by radio-frequency plasma enhanced reactive thermal evaporation is studied, as transport properties are expected to improve with doping. Undoped and tin doped indium oxide thin films are deposited at room temperature using both pure In rods and (95–80) % In:(5–20) % Sn alloys as evaporation sources and 19.5 mW/cm 2 and 58.6 mW/cm 2 as rf-power densities. The two most important macroscopic properties – visible transparency and electrical resistivity – are relatively independent of tin content (0–20%). Visible transmittance of about 75% and electrical resistivity around 5 × 10 −4 Ω·cm can be observed in the films. The structural features are similar for all samples. Nevertheless, the surface morphology characterization shows that the homogeneity of the films varies according to the tin content. Moreover this variation is a balance between the rf-power and the tin content in the alloy: i) films with small and compact grains are produced at 58.6 mW/cm 2 from a 5% Sn alloy or at 19.5 mW/cm 2 from a 15% Sn alloy and consequently, smooth surfaces with reduced roughness and similar grain size and shape are obtained; ii) films showing the presence of aggregates randomly distributed above a tissue formed of thinner grains and higher roughness are produced at the other deposition conditions. - Highlights: ► InO x :Sn and InO x thin films were deposited at room temperature. ► Transparency and electrical resistivity are relatively independent of Sn content. ► Device quality material was obtained. ► The surface morphology homogeneity of the films varies with tin content.

  5. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    International Nuclear Information System (INIS)

    Herchko, S; Ding, G

    2016-01-01

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  6. Pulse-Driven Capacitive Lead Ion Detection with Reduced Graphene Oxide Field-Effect Transistor Integrated with an Analyzing Device for Rapid Water Quality Monitoring.

    Science.gov (United States)

    Maity, Arnab; Sui, Xiaoyu; Tarman, Chad R; Pu, Haihui; Chang, Jingbo; Zhou, Guihua; Ren, Ren; Mao, Shun; Chen, Junhong

    2017-11-22

    Rapid and real-time detection of heavy metals in water with a portable microsystem is a growing demand in the field of environmental monitoring, food safety, and future cyber-physical infrastructure. Here, we report a novel ultrasensitive pulse-driven capacitance-based lead ion sensor using self-assembled graphene oxide (GO) monolayer deposition strategy to recognize the heavy metal ions in water. The overall field-effect transistor (FET) structure consists of a thermally reduced graphene oxide (rGO) channel with a thin layer of Al 2 O 3 passivation as a top gate combined with sputtered gold nanoparticles that link with the glutathione (GSH) probe to attract Pb 2+ ions in water. Using a preprogrammed microcontroller, chemo-capacitance based detection of lead ions has been demonstrated with this FET sensor. With a rapid response (∼1-2 s) and negligible signal drift, a limit of detection (LOD) < 1 ppb and excellent selectivity (with a sensitivity to lead ions 1 order of magnitude higher than that of interfering ions) can be achieved for Pb 2+ measurements. The overall assay time (∼10 s) for background water stabilization followed by lead ion testing and calculation is much shorter than common FET resistance/current measurements (∼minutes) and other conventional methods, such as optical and inductively coupled plasma methods (∼hours). An approximate linear operational range (5-20 ppb) around 15 ppb (the maximum contaminant limit by US Environmental Protection Agency (EPA) for lead in drinking water) makes it especially suitable for drinking water quality monitoring. The validity of the pulse method is confirmed by quantifying Pb 2+ in various real water samples such as tap, lake, and river water with an accuracy ∼75%. This capacitance measurement strategy is promising and can be readily extended to various FET-based sensor devices for other targets.

  7. Structural, optical and morphological properties of post-growth calcined TiO{sub 2} nanopowder for opto-electronic device application: Ex-situ studies

    Energy Technology Data Exchange (ETDEWEB)

    Sathyaseelan, B., E-mail: bsseelan03@gmail.com [Dept of Physics, University College of Engineering Arni (A Constituent College of Anna University Chennai) Arni 632326, Tamil Nadu (India); Manikandan, E., E-mail: maniphysics@gmail.com [Central Research Laboratory, Sree Balaji Medical College & Hospital, Bharath University, BIHER, Chrompet, Chennai 600044, Tamil Nadu (India); UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Lakshmanan, V. [Dept of Physics, A.C.T College of Engineering & Technology, Nelvoy 603107 Kancheepuram (Dt), Tamil Nadu (India); Baskaran, I. [Dept of Physics, Arignar Anna Government Arts College, Cheyyar 604407, Tamil Nadu (India); Sivakumar, K. [Dept of Physics, Anna University, Chennai 600025, Tamil Nadu (India); Ladchumananandasivam, Rasiah [Dept of Textile Engineering & Post Graduate Programme in Mechanical Engineering Centre of Technology, Federal University of Rio Grande do Norte, Natal (Brazil); Kennedy, J. [UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington (New Zealand); Maaza, M., E-mail: maaza@tlabs.ac.za [UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa)

    2016-06-25

    Nanocrystalline TiO{sub 2} powders have been selectively prepared by the simple combustion reaction method using urea as a fuel. The crystalline powder was obtained using a silica basin heated directly on a hot plate at 500 °C until self-ignition occurred. After combustion process, the calcined products were obtained by heating the as-prepared powders for 1 h in air atmosphere at various sintering temperatures [500–900 °C]. The obtained nanopowder materials were systematically characterized by X-day diffraction (XRD), micro-Raman, UV–visible absorption (UV–vis), and Fourier transform infrared (FT-IR) spectroscopics. Powder XRD pattern shows the good agreement rutile phase structured TiO{sub 2} and the sharp diffraction peaks indicates good for crystallinity. The size of a symmetry of the nanoparticles have been measured with aid of a scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), and Brunauer, Emmett and Teller (BET) surface studies. The crystallinity of the powders was found to increase with respect to calcination temperatures. The average specific surface area of the particle was probed using gas adsorption–desorption measurements. Raman spectroscopy experiment was performed to ascertain the nature of TiO{sub 2} powder quality. UV–vis absorption spectra results showed the changes in the absorption edges of TiO{sub 2} report to increasing the calcinations temperatures. - Highlights: • TiO{sub 2} Nanocrystalline powders were prepared by simple combustion reaction method. • Calcined TiO{sub 2} nanopowder obtained by heating for 1 hr in air atmosphere at 500–900 °C. • Systematic characterization employed by XRD, micro-Raman, Optical, SEM, HRTEM. • The size symmetry of nanoparticles measured by electron microscopes BET methods. • Calcinations raises the crystallinity size enhanced for future opto-electronic devices.

  8. Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

    KAUST Repository

    Wang, Mingkui

    2009-01-01

    We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. © 2009 The Royal Society of Chemistry.

  9. Structure, microstructure and photoluminescence of nanocrystalline Ti-doped gahnite

    Energy Technology Data Exchange (ETDEWEB)

    Vrankic, M., E-mail: mvrankic@irb.hr [Ruder Boskovic Institute, Division of Materials Physics, Bijenicka cesta 54, P.O. Box 180, HR-10002 Zagreb (Croatia); Grzeta, B. [Ruder Boskovic Institute, Division of Materials Physics, Bijenicka cesta 54, P.O. Box 180, HR-10002 Zagreb (Croatia); Mandic, V.; Tkalcec, E. [University of Zagreb, Faculty of Chemical Engineering and Technology, Marulicev trg 19, HR-10000 Zagreb (Croatia); Milosevic, S. [Institute of Physics, Bijenicka cesta 46, P.O. Box 304, HR-10002 Zagreb (Croatia); Ceh, M. [Jozef Stefan Institute, Department for Nanostructured Materials, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Rakvin, B. [Ruder Boskovic Institute, Division of Physical Chemistry, Bijenicka cesta 54, P.O. Box 180, HR-10002 Zagreb (Croatia)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Ti-doped gahnite samples with 0-11.6 at.% Ti were synthesized for the first time. Black-Right-Pointing-Pointer The samples had crystallite size of 16.6-20.5 nm and lattice strain of 0.07-0.26%. Black-Right-Pointing-Pointer Titanium entered the gahnite structure as Ti{sup 4+}, substituting for octahedral Al{sup 3+}. Black-Right-Pointing-Pointer Ti-doped gahnite showed the UV absorption and blue emission under UV excitation. - Abstract: A series of Ti-doped ZnAl{sub 2}O{sub 4} (gahnite) samples with doping levels of 0, 1.8, 3.8, 5.4 and 11.6 at.% Ti in relation to Al were prepared by a sol-gel technique. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), EPR spectroscopy, UV-vis reflectance spectroscopy and photoluminescence (PL) studies. Diffraction patterns indicated that all samples were nanocrystalline, with a spinel-type structure, space group Fd3{sup Macron }m. Titanium doping of gahnite caused an increase of unit-cell parameter and diffraction line broadening. The structure of samples was refined by the Rietveld method, simultaneously with the analysis of diffraction line broadening. TEM investigations confirmed that samples had spinel-type structure, and showed that samples contained evenly shaped particles of about 20 nm in size. Ti-doped samples exhibited strong absorption at wavelength <400 nm, and blue photoluminescence under excitation with {lambda}{sub exc} = 308 nm.

  10. Effect of Aminosilane Modification on Nanocrystalline Cellulose Properties

    Directory of Open Access Journals (Sweden)

    Nurul Hanisah Mohd

    2016-01-01

    Full Text Available The application of renewable nanomaterials, like nanocrystalline cellulose (NCC, has recently been widely studied by many researchers. NCC has many benefits such as high aspect ratio, biodegradability, and high number of hydroxyl groups which offer great opportunities for modification. In this study, the NCC derived from empty fruit bunches (EFB was modified with aminosilane, 3-(2-aminoethylaminopropyl-dimethoxymethylsilane (AEAPDMS, and the characterization was performed to investigate the potential as carbon dioxide (CO2 capture. Modification of NCC with AEAPDMS was carried out in water/ethanol solvent (80/20 (v/v with a ratio of NCC to aminosilane of 1 : 1, 1 : 2, 1 : 3, and 1 : 4 w/w%. The effects of AEAPDMS on NCC were characterized using Fourier transform infrared (FTIR spectroscopy, thermogravimetric analysis (TGA, X-ray diffraction (XRD analysis, elemental analysis (CHNS, and transmission electron microscopy (TEM. The existence of AEAPDMS onto NCC was confirmed by ATR-FTIR spectroscopy as the new peaks of NH2 were bending and wagging, and Si-CH3 appeared. The thermal stability of NCC increased after modification due to the interaction with AEAPDMS. The elemental analysis result showed that the nitrogen content increased with an enhancement ratio of the modifiers. The XRD indicated that the crystallinity decreased while the rod-like geometry of NCC was maintained after amorphous AEAPDMS grafted on the NCC. Since AEAPDMS can be grafted on the NCC, the sample is applicable as CO2 capture.

  11. Dielectric properties of nanocrystalline Co-Mg ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jyoti, E-mail: jyotijoshi.phy2008@gmail.com [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, Neha [Department of Physics, VEC Lakhanpur, Sarguja University, Ambikapur (C.G.) (India); Parashar, Jyoti; Saxena, V.K.; Bhatnagar, D. [Department of Physics, University of Rajasthan, Jaipur (India); Sharma, K.B. [Department of Physics, S. S. Jain Subodh P. G. College, Jaipur (India)

    2015-11-15

    Nanocrystalline powder samples with chemical formula Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been synthesized by sol–gel auto combustion method using citric acid as fuel agent. The rietveld refinement study of x-ray diffraction patterns confirmed the spinel single phase formation for all samples. Dielectric constant (ε′), dielectric loss tangent (tan δ) and AC conductivity of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles have been measured at room temperature in the frequency range from 1000 Hz to 120 MHz. The dielectric dispersion observed at lower frequency region is attributed to Maxwell–Wagner two layer model, which is in agreement with Koops phenomenological theory. The observed results have been explained by polarization which is attributed to the electron exchange between Fe{sup 2+} and Fe{sup 3+} ions. The temperature variation of ε′ and tanδ for some particular frequencies were studied. The rapid increase in ε′ and tan δ has been explained using thermally activated electron exchange between Fe{sup 2+} ↔ Fe{sup 3+} and Co{sup 2+} ↔ Co{sup 3+} ions at adjacent octahedral sites. The role of interfacial polarization has been focused to explain the high dispersion in ε′ and tanδ with temperature observed at low frequencies. - Graphical abstract: (a) TEM image of Co{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} shows the nano size of the synthesized ferrite particles and (b) Dielectric constant behavior with frequency of Co{sub x}Mg{sub 1−x}Fe{sub 2}O{sub 4} ferrite.

  12. Biodegradation of nanocrystalline cellulose by two environmentally-relevant consortia.

    Science.gov (United States)

    Singh, Gargi; Chandoha-Lee, Cody; Zhang, Wei; Renneckar, Scott; Vikesland, Peter J; Pruden, Amy

    2016-11-01

    Nanocellulose is growing in popularity due to its versatile properties and applications. However, there is a void of knowledge regarding the environmental fate of nanocellulose and the response of environmental microbial communities that are historically adapted to non-nano cellulose forms. Given its distinction in terms of size and chemical and physical properties, nanocellulose could potentially resist biodegradation and/or pose a xenobiotic influence on microbial communities during wastewater treatment or in receiving environments. In this study, biodegradation of H 2 SO 4 hydrolyzed nanocrystalline cellulose (HNC) was compared with that of microcrystalline cellulose using two distinct anaerobic cellulose-degrading microbial consortia initially sourced from anaerobic digester (AD) and wetland (W) inocula. Equivalent cellulose masses were dosed and monitored with time by measurement of liberated glucose. HNC biodegraded at slightly faster rate than microcrystalline cellulose (1st order decay constants: 0.62 ± 0.08 wk -1 for HNC versus 0.39 ± 0.05 wk -1 for microcrystalline cellulose for the AD consortium; 0.69 ± 0.04 wk -1 for HNCversus 0.58 ± 0.05 wk -1 for microcrystalline cellulose for the W consortium). 16S rRNA (total bacteria) and cel48 (glycoside hydrolase gene family 48, indicative of cellulose-degrading potential) genes were observed to be more enriched in the HNC condition for both consortia. According to Illumina amplicon sequencing of 16S rRNA genes, the composition of the consortia underwent distinct shifts in concert with HNC versus microcrystalline cellulose degradation. This study demonstrates that the biodegradation of cellulose is not inhibited in the nano-size range, particularly in the crystalline form, though the microbes and pathways involved likely differ. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Formation of Nano-crystalline Todorokite from Biogenic Mn Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Feng, X.; Zhu, M; Ginder-Vogel, M; Ni, C; Parikh, S; Sparks, D

    2010-01-01

    Todorokite, as one of three main Mn oxide phases present in oceanic Mn nodules and an active MnO{sub 6} octahedral molecular sieve (OMS), has garnered much interest; however, its formation pathway in natural systems is not fully understood. Todorokite is widely considered to form from layer structured Mn oxides with hexagonal symmetry, such as vernadite ({delta}-MnO{sub 2}), which are generally of biogenic origin. However, this geochemical process has not been documented in the environment or demonstrated in the laboratory, except for precursor phases with triclinic symmetry. Here we report on the formation of a nanoscale, todorokite-like phase from biogenic Mn oxides produced by the freshwater bacterium Pseudomonas putida strain GB-1. At long- and short-range structural scales biogenic Mn oxides were transformed to a todorokite-like phase at atmospheric pressure through refluxing. Topotactic transformation was observed during the transformation. Furthermore, the todorokite-like phases formed via refluxing had thin layers along the c* axis and a lack of c* periodicity, making the basal plane undetectable with X-ray diffraction reflection. The proposed pathway of the todorokite-like phase formation is proposed as: hexagonal biogenic Mn oxide {yields} 10-{angstrom} triclinic phyllomanganate {yields} todorokite. These observations provide evidence supporting the possible bio-related origin of natural todorokites and provide important clues for understanding the transformation of biogenic Mn oxides to other Mn oxides in the environment. Additionally this method may be a viable biosynthesis route for porous, nano-crystalline OMS materials for use in practical applications.

  14. The Quality of Healthcare Service Delivery in Nigeria: An Assessment of the Availability of Some Basic Medical Devices/Equipment in the Primary Health Care Centres in Delta State

    Directory of Open Access Journals (Sweden)

    Omuta GED

    2016-05-01

    Full Text Available Background: Ordinarily, accessibility implies locational proximity. However, this study limits its use to the quality of what is accessed. There is, therefore, service-delivery inaccessibility, when health care seekers can only access poor quality service, because of the poor quality of the equipment at the disposal of primary health care centres. Service-delivery equipment are, therefore, surrogate indicators of the quality of the health care services that are geographically accessible. Methodology: Both qualitative and quantitative approaches of investigation were deployed, using structured questionnaires and focus group discussions/key informant interviews, respectively. It covered nine local government areas, three each from the senatorial districts. The paper discusses three basic medical devices/equipment that determine the quality of services delivered by PHCs, namely available and functioning general purpose equipment; most commonly used methods of sterilization; and availability of different types of laboratory tests. The quantitative data were cleaned up, processed and analysed, using the SPSS 10.0. Results: There were variations in the availability of devices and equipment. Syringes/needles and stethoscopes were available in more than three-quarters of the centres, while less than ten (10 per cent had microscopes. About 15 per cent of the centres either had no methods of sterilization at all or used ‘inappropriate’ ones. In spite of the prevalence of malaria, only 28.89 per centres could test for the parasite. Conclusion: The quality of services were perceived as poor because the basic medical devices and equipment were either lacking or inadequate. Policy implication is that government should increase resource allocation to the PHC subsector to procure the basic facilities for efficient service delivery.

  15. Control of Ga-oxide interlayer growth and Ga diffusion in SiO2/GaN stacks for high-quality GaN-based metal–oxide–semiconductor devices with improved gate dielectric reliability

    Science.gov (United States)

    Yamada, Takahiro; Watanabe, Kenta; Nozaki, Mikito; Yamada, Hisashi; Takahashi, Tokio; Shimizu, Mitsuaki; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2018-01-01

    A simple and feasible method for fabricating high-quality and highly reliable GaN-based metal–oxide–semiconductor (MOS) devices was developed. The direct chemical vapor deposition of SiO2 films on GaN substrates forming Ga-oxide interlayers was carried out to fabricate SiO2/GaO x /GaN stacked structures. Although well-behaved hysteresis-free GaN-MOS capacitors with extremely low interface state densities below 1010 cm‑2 eV‑1 were obtained by postdeposition annealing, Ga diffusion into overlying SiO2 layers severely degraded the dielectric breakdown characteristics. However, this problem was found to be solved by rapid thermal processing, leading to the superior performance of the GaN-MOS devices in terms of interface quality, insulating property, and gate dielectric reliability.

  16. Multifunctional alumina/titania hybrid blocking layer modified nanocrystalline titania films as efficient photoanodes in dye sensitized solar cells

    Science.gov (United States)

    Wang, Changlei; Yu, Zhenhua; Bu, Chenghao; Liu, Pei; Bai, Sihang; Liu, Chang; Kondamareddy, Kiran Kumar; Sun, Weiwei; Zhan, Kan; Zhang, Kun; Guo, Shishang; Zhao, Xingzhong

    2015-05-01

    A facile way of fabricating efficient blocking layer on mesoporous TiO2 film of dye-sensitized solar cells (DSSCs) is demonstrated here for the first time. Al2O3 and TiO2 are combined together to form a blocking layer. A simple spin coating technique is employed which is a versatile and low-cost method over the atomic layer deposition (ALD) technique. Multifunctional alumina/titania (Al2O3/TiO2) hybrid overlayer is prepared on traditional TiO2 nanocrystalline thin film surface, through sequential deposition of AlCl3·6H2O and TiCl4 precursor solutions followed by sintering at 500 °C for 30 min. Al2O3 effectively plays its role in retarding interfacial recombination of electrons and improving open circuit potential (Voc), while the tiny TiO2 clusters synthesized from TiCl4 treatment act as electron transporting channels to facilitate electron diffusion which leads to enhanced photocurrent (Jsc). Compared to the device without blocking layer, the DSSCs assembled with Al2O3/TiO2 hybrid blocking layer showed improvement in Jsc (from 13.09 mA/cm2 to 16.90 mA/cm2) as well as in Voc (from 0.72 V to 0.73 V) resulting a much better conversion efficiency of 8.60%.

  17. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  18. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    Science.gov (United States)

    Gruen, Dieter M [Downers Grove, IL

    2009-08-11

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  19. Bioorganic nanodots for non-volatile memory devices

    International Nuclear Information System (INIS)

    Amdursky, Nadav; Shalev, Gil; Handelman, Amir; Natan, Amir; Rosenwaks, Yossi; Litsyn, Simon; Szwarcman, Daniel; Rosenman, Gil; Roizin, Yakov

    2013-01-01

    In recent years we are witnessing an intensive integration of bio-organic nanomaterials in electronic devices. Here we show that the diphenylalanine bio-molecule can self-assemble into tiny peptide nanodots (PNDs) of ∼2 nm size, and can be embedded into metal-oxide-semiconductor devices as charge storage nanounits in non-volatile memory. For that purpose, we first directly observe the crystallinity of a single PND by electron microscopy. We use these nanocrystalline PNDs units for the formation of a dense monolayer on SiO 2 surface, and study the electron/hole trapping mechanisms and charge retention ability of the monolayer, followed by fabrication of PND-based memory cell device

  20. Devices for fatigue testing of electroplated nickel (MEMS)

    DEFF Research Database (Denmark)

    Larsen, Kristian Pontoppidan; Ravnkilde, J. T.; Ginnerup, Morten

    2002-01-01

    In-situ fatigue test devices with integrated electrostatic actuator were fabricated in electroplated nanocrystalline nickel (nano-nickel). The devices feature in-plane approximately pure bending with fixed displacement of the test specimen of the dimensions: widths from 2μm to 3.7μm, a height of 7......μm and an effective length from 4μm to 27μm. Maximum stresses of the test beam were calculated to be 500MPa to 2100MPa by use of FEM tools. The test results indicate very promising fatigue properties of nano-nickel, as none of the test devices have shown fatigue failure or even initiation of cracks...

  1. Boron-doped nanocrystalline diamond electrodes for neural interfaces: in vivo biocompatibility evaluation

    Czech Academy of Sciences Publication Activity Database

    Alcaide, M.; Taylor, Andrew; Fjorback, M.; Zachar, V.; Pennisi, C.P.

    2016-01-01

    Roč. 10, Mar (2016), 1-9, č. článku 87. ISSN 1662-453X Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * neuroprosthetic interfaces * neural electrodes * boron-doped diamond * titanium nitride * foreign body reaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.566, year: 2016

  2. Visible-light sensitization of boron-doped nanocrystalline diamond through non-covalent surface modification

    Czech Academy of Sciences Publication Activity Database

    Krýsová, Hana; Vlčková Živcová, Zuzana; Bartoň, Jan; Petrák, Václav; Nesladek, M.; Cígler, Petr; Kavan, Ladislav

    2015-01-01

    Roč. 17, č. 2 (2015), s. 1165-1172 ISSN 1463-9076 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:61388963 ; RVO:68378271 Keywords : nanocrystallines * visible-light sensitization * boron-doped diamond Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.449, year: 2015

  3. Ferromagnetic resonance investigation of nanocrystalline FeCuNbSiB

    Indian Academy of Sciences (India)

    Figure 2. MS vs. T3/2 plots. The symbols open circles (amorphous) and open triangles (nanocrystalline) represent the data while the continuous curves denote the best least-square fits based on eqs (1) and (2). [7]. HK either depends on temperature or is constant, H0. K, over a certain tem- perature range. In the temperature ...

  4. Growth and characterization of nanocrystalline diamond/amorphous carbon composite films prepared by MWCVD

    Czech Academy of Sciences Publication Activity Database

    Popov, C.; Kulisch, W.; Gibson, P. N.; Ceccone, G.; Jelínek, Miroslav

    2004-01-01

    Roč. 13, - (2004), s. 1371-1376 ISSN 0925-9635 Institutional research plan: CEZ:AV0Z1010921 Keywords : nanocrystalline * diamond films * plasma CVD * microstructure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.670, year: 2004

  5. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Directory of Open Access Journals (Sweden)

    Yuxin Wang

    2017-08-01

    Full Text Available In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM. The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at% Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts.

  6. Prefilming twin-fluid nozzle assisted precipitation method for preparing nanocrystalline HNS and its characterization.

    Science.gov (United States)

    Wang, Jingyu; Huang, Hao; Xu, Wen Zheng; Zhang, Yu Ruo; Lu, Bin; Xie, Rui Zheng; Wang, Peiyong; Yun, Ni

    2009-03-15

    The ultra-fine HNS (2,2',4,4',6,6'-hexanitrostilbene) with desired properties is needed for military and civilian applications because of its reliable threshold energy to short impulse shock waves and its excellent thermal and shock stability. This paper reports on prefilming twin-fluid nozzle assisted precipitation (PTFN-P) to obtain ultra-fine HNS explosive with high specific surface area (SSA), high purity, and narrow particle size distribution. The properties of ultra-fine HNS have been confirmed by SEM, BET, HPLC, XRD, DSC and TGA-SDTA. SEM photograph revealed that the PTFN-P process offers ellipsoid crystalline morphology with particle size of 90-150 nm. The BET and Langmuir SSA of nanocrystalline HNS with purity of 99.44 wt.% were determined to be 19.28 m(2)/g and 29.26 m(2)/g, respectively. The XRD peaks of nanocrystalline HNS seemed to have similar diffraction angles as those of synthesized HNS, and the weakening of peak strength was observed apparently. DSC results of the nanocrystalline HNS showed that the exothermic decomposing at the temperature range of 323-398 degrees C. Furthermore, HNS samples were submitted to impact and small scale gap test and the results indicated that nanocrystalline HNS is less sensitive than synthesized HNS (50 microm) to impact and shock stimuli.

  7. Fabrication and properties of Er-doped nanocrystalline phase-seperated optical fibers

    Czech Academy of Sciences Publication Activity Database

    Dhar, Anirban; Kašík, Ivan; Podrazký, Ondřej; Matějec, Vlastimil

    2013-01-01

    Roč. 11, č. 1 (2013), s. 29-35 ISSN 1336-1376 R&D Projects: GA ČR GPP102/10/P554; GA ČR GAP102/10/2139 Institutional support: RVO:67985882 Keywords : Er-doping * Phase-separated glass * Nano-crystalline optical fiber Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  8. A Low Temperature Synthetic Route to Nanocrystalline TiN | Cai ...

    African Journals Online (AJOL)

    A simple chemical synthetic route has been developed to prepare nanocrystalline titanium nitride (TiN) in an autoclave, by the reaction of metallic Ti with NaNH2 at low temperature of 500–600 °C. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron ...

  9. Influence of grain boundaries on elasticity and thermal conductivity of nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Mohr, Markus; Daccache, Layal; Horvat, Sebastian; Brühne, Kai; Jacob, Timo; Fecht, Hans-Jörg

    2017-01-01

    Diamond combines several outstanding material properties such as the highest thermal conductivity and highest elastic moduli of all materials. This makes diamond an interesting candidate for a multitude of applications. Nonetheless, nanocrystalline diamond films, layers and coatings, usually show properties different to those of single crystalline diamond. This is usually attributed to the larger volume fraction of the grain boundaries with atomic structure different from the single crystal. In this work we measured Young's modulus and thermal conductivity of nanocrystalline diamond films with average grain sizes ranging from 6 to 15 nm. The measured thermal conductivities are modeled considering the thermal boundary conductance between grains as well as a grain size effect on the phonon mean free path. We make a comparison between elastic modulus and thermal boundary conductance of the grain boundaries G k for different nanocrystalline diamond films. We conclude that the grain boundaries thermal boundary conductance G k is a measure of the cohesive energy of the grain boundaries and therefore also of the elastic modulus of the nanocrystalline diamond films.

  10. Influence of nanocrystalline diamond on resonant properties of gold plasmonic antennas

    Czech Academy of Sciences Publication Activity Database

    Kvapil, M.; Kromka, Alexander; Rezek, Bohuslav; Kalousek, R.; Křápek, V.; Dub, P.; Šikola, T.

    2016-01-01

    Roč. 213, č. 6 (2016), 1564-1571 ISSN 1862-6300 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : antenna resonance wavelength * electric field enhancement * FDTD * nanocrystalline diamond * plasmonic antenna Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.775, year: 2016

  11. Nanocrystalline TiO2 by three different synthetic approaches: A ...

    Indian Academy of Sciences (India)

    TECS

    templating, mechanochemical synthesis and combustion synthesis for the production of nanostructured TiO2, is reported. In the sol–gel method, nanocrystalline TiO2 is produced when titanium tetraisopropoxide is tem- plated onto dodecylamine which forms the liquid crystalline hexagonal structure and the template is then.

  12. Supported lipid bilayer on nanocrystalline diamond: dual optical and field-effect sensor for membrane disruption

    Czech Academy of Sciences Publication Activity Database

    Ang, P.K.; Loh, K.P.; Wohland, T.; Nesládek, Miloš; Van Hove, E.

    2009-01-01

    Roč. 19, č. 1 (2009), s. 109-116 ISSN 1616-301X Institutional research plan: CEZ:AV0Z10100520 Keywords : nanocrystalline diamond * biocompatibility * supported lipid bilayers * biosensors * solution gate field effect transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.990, year: 2009

  13. Role of grain size in superconducting boron-doped nanocrystalline diamond thin films grown by CVD

    Czech Academy of Sciences Publication Activity Database

    Zhang, G.; Janssens, S.D.; Vanacken, J.; Timmermans, M.; Vacík, Jiří; Ataklti, G.W.; Decelle, W.; Gillijns, W.; Goderis, B.; Haenen, K.; Wagner, P.; Moshchalkov, V.V.

    2011-01-01

    Roč. 84, č. 21 (2011), 214517/1-214517/10 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10480505 Keywords : Nanocrystalline diamond * Superconducting transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  14. Optical properties of nanocrystalline HfO2 synthesized by an auto-igniting combustion synthesis

    Directory of Open Access Journals (Sweden)

    H. Padma Kumar

    2015-03-01

    Full Text Available The optical properties of nanocrystalline HfO2 synthesized using a single-step auto-igniting combustion technique is reported. Nanocrystalline hafnium oxide having particle size of the order 10–15 nm were obtained in the present method. The nanopowder was characterized using X-ray diffraction, Fourier transform infrared and Fourier transform Raman spectroscopic studies. All these studies confirm that the phase formation is complete in the combustion synthesis and monoclinic phase [P21/c(14] of HfO2 is obtained without the presence of any impurities or additional phases. The powder morphology of the as-prepared sample was studied using transmission electron microscopy and the results were in good agreement with that of the X-ray diffraction studies. The optical constants such as refractive index, extinction coefficient, optical conductivity and the band gap were estimated from UV–vis spectroscopic techniques. The band gap of nanocrystalline HfO2 was found to be 5.1 eV and the sample shows a broad PL emission at 628 nm. It is concluded that the transitions between intermediate energy levels in the band gap are responsible for the interesting photoluminescent properties of nanocrystalline HfO2.

  15. High frequency magnetic properties of Fe-based nanocrystalline alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.K. [Seoul National University of Technology, Seoul 139-743 (Korea); Korea Institute of Science and Technology, Seoul 136-791 (Korea); Kim, Yoon B.; Jee, K.K. [Korea Institute of Science and Technology, Seoul 136-791 (Korea); Choi, G.B. [R and D Center, Changsung Corporation, Incheon (Korea)

    2007-12-15

    Toroidal shape Fe-based nanocrystalline alloy powder cores were prepared from the melt spun Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} ribbons by cold pressing using silicon and phenol resin as an insulating material, respectively. The effect of the insulating materials and their content on the high-frequency magnetic properties of the compacted cores were investigated. The Fe-based nanocrystalline alloy powder cores using phenol resin exhibit stable permeability over 1 MHz, showing excellent high-frequency characteristics. The core loss was reduced significantly and the dc-bias property was improved by using phenol resin. Uniform and good insulation by phenol resin leads to the excellent high-frequency characteristics of the cores. Silicon resin as an insulating material was also effective in improving the high frequency characteristics of the Fe-based nanocrystalline alloy powder cores. However, an appropriate coating process for silicon resin should be applied in order to achieve more improved high frequency characteristics of the nanocrystalline alloy powder cores by controlling the thickness of coated layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. A novel method for synthesizing nano-crystalline MgTiO3 geikielite

    Indian Academy of Sciences (India)

    synthesis of nano-crystalline geikielite by co-precipi- tation method. The sample has been characterized by electron microscopic, powder X-ray diffraction and Fourier– transform infrared (FT–IR) spectroscopic methods. 2. Experimental. Geikielite sample has been prepared by co-precipitation method through the reaction: ...

  17. Vibrational thermodynamics of Fe90Zr7B3 nanocrystalline alloy from nuclear inelastic scattering

    DEFF Research Database (Denmark)

    Stankov, S.; Miglierini, M.; Chumakov, A. I.

    2010-01-01

    Recently we determined the iron-partial density of vibrational states (DOS) of nanocrystalline Fe(90)Zr(7)B(3) (Nanoperm), synthesized by crystallization of an amorphous precursor, for various stages of nanocrystallization separating the DOS of the nanograins from that of the interfaces [S. Stank...

  18. Phase-pure Nanocrystalline Li4Ti5O12 for Lithium ion Battery

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Zukalová, Markéta; Kavan, Ladislav

    2003-01-01

    Roč. 8, č. 1 (2003), s. 2-6 ISSN 1432-8488 R&D Projects: GA MŠk OC D14.10 Institutional research plan: CEZ:AV0Z4040901 Keywords : phase purity * Li4Ti5O12 * nanocrystalline materials Subject RIV: CG - Electrochemistry Impact factor: 1.195, year: 2003

  19. Effect of plating time on growth of nanocrystalline Ni–P from ...

    Indian Academy of Sciences (India)

    Nanocrystalline nickel phosphorus (NC-Ni–P) deposits from sulphate/glycine bath using a simple electroless deposition process is demonstrated. In the present investigation, nanoporous alumina films are formed on the aluminium surface by anodization process followed by deposition of nickel onto the pores by electroless ...

  20. Effect of plating time on growth of nanocrystalline Ni–P from ...

    Indian Academy of Sciences (India)

    Nanocrystalline nickel phosphorus (NC-Ni–P) deposition has been an emerging area for researchers and scientists due to its applications in chemical, aerospace, automobile and textile industries (Mallory and Hajdu 1990; Parker 1992), since the discovery of electroless nickel–phosphorus (ENP) coatings (Brenner and ...