WorldWideScience

Sample records for single piece mechanisms

  1. Optimized design and structural mechanics of a single-piece composite helicopter driveshaft

    Science.gov (United States)

    Henry, Todd C.

    In rotorcraft driveline design, single-piece composite driveshafts have much potential for reducing driveline mass and complexity over multi-segmented metallic driveshafts. The singlepiece shaft concept is enabled by the relatively high fatigue strain capacity of fiber reinforced polymer composites over metals. Challenges for single-piece driveshaft design lie in addressing the self-heating behavior of the composite due to the material damping, as well as, whirling stability, torsional buckling stability, and composite strength. Increased composite temperature due to self-heating reduces the composite strength and is accounted for in this research. The laminate longitudinal stiffness ( Ex) and strength (Fx) are known to be heavily degraded by fiber undulation, however, both are not well understood in compression. The whirling stability (a function of longitudinal stiffness) and the composite strength are strongly influential in driveshaft optimization, and thus are investigated further through the testing of flat and filament wound composite specimens. The design of single-piece composite driveshafts, however, needs to consider many failure criteria, including hysteresis-induced overheating, whirl stability, torsional buckling stability, and material failure by overstress. The present investigation uses multi-objective optimization to investigate the design space which visually highlights design trades. Design variables included stacking sequence, number of laminas, and number of hanger bearings. The design goals were to minimize weight and maximize the lowest factor of safety by adaptively generating solutions to the multi-objective problem. Several design spaces were investigated by examining the effect of misalignment, ambient temperature, and constant power transmission on the optimized solution. Several materials of interest were modeled using experimentally determined elastic properties and novel temperature-dependent composite strength. Compared to the

  2. Pieces

    DEFF Research Database (Denmark)

    Jensen, Henrik

    1990-01-01

    The report presents results from the SIP project (System Representation in Process Control). PIECES is a graphical, interactive user interface system designed and programmed as a tool for building, manipulating and using a Multilevel Flow Model (MFM - Morten Lind, Tecnical University of Denmark......). An MFM describes a plant by describing the condition and the flow of its materials (mass, energy), which form the process. Pieces is programmed in Smalltalk. This report describes the programme, its hierarchy of classes and the methods of the classes. This report is 2 of 2. Report 1: Design of PIECES...

  3. Immediate loading with single-piece implant following extraction

    Directory of Open Access Journals (Sweden)

    Hemlata Dwivedi

    2017-01-01

    Full Text Available Although dental implantology had evolved over a number of years, many dental surgeons are unaware of the concept of immediate loading with the use of one-piece implant that began in the early 1960s. The goal of successful prosthodontics rehabilitation is to provide function, esthetics, and comfort to the patient. The aim of this literature is to provide an overview of one-piece implant, with its advantages and disadvantages over conventional two-piece implant. Immediate prosthetic of a one-piece system allows for a better tissue healing and better adhesion of gingival mucosa to form a collar which is healthy and adherent to the implant, avoiding a second surgical procedure, and also includes a very important aspect esthetics. This article describes a case report of immediate loading with single-piece implant following extraction.

  4. Pieces

    DEFF Research Database (Denmark)

    Jensen, Henrik

    1990-01-01

    The report presents results from the SIP project (System Representation in Process Control). PIECES is a graphical, interactive user interface system designed and programmed as a tool for building, manipulating and using a Multilevel Flow Model (MFM - Morten Lind, Tecnical University of Denmark...

  5. Pieces

    DEFF Research Database (Denmark)

    Jensen, Niels Henrik

    1990-01-01

    The report presents results from the SIP project (System Representation in Process Control). PIECES is a graphical, interactive user interface system designed and programmed as a tool for building, manipulating and using a Multilevel Flow Model (MFM - Morten Lind, Tecnical University of Denmark)....

  6. The impact of mechanical properties of rock to the collision of rock piece

    Directory of Open Access Journals (Sweden)

    Borut Macuh

    2007-06-01

    Full Text Available The paper presents the analytical solution of the rock piece motion considering influences of geometrical and mechanical characteristics of rock mass on the arbitrary slope. The main objective of the paper is to determine the motion of the rock piece considering possibility of rock piece failure due to collision. Brief description of the analytical solution of the rock piece motion on a steep slope is given. The laboratory tests were performed to determine uniaxial compressive strength and elastic properties of the considered rock mass. Further, velocities that cause rock piece failure were determined. These maximum velocities indirectly belong to certain mass of rock piece and can be lower than velocities calculated in rock-fall analysis for certain slope geometry. Consequently, the energy magnitude is limited, because at certain velocity and mass of rock piece bigger pieces crash at collision.

  7. Scleral fixation of a single-piece multifocal intraocular lens.

    Science.gov (United States)

    Can, Ertugrul; Basaran, M Resat; Gül, Adem

    2013-01-01

    We describe an ab interno technique for injector implantation of a one-piece multifocal intraocular lens (IOL). Transscleral fixation of multifocal posterior chamber IOL implantation using an injector with ab interno technique was performed in an eye of a 9-year-old girl who had undergone pars plana lensectomy 2 years before for bilateral lens subluxation with unknown etiology. No major complications were encountered during a 3-month follow-up of the patient and excellent centration was observed during the follow-up period. Her preoperative best spectacle-corrected distance visual acuity of 20/32 improved to uncorrected distance visual acuity of 20/25. Closed-loop design of IOL served the function of eyelets and position of the IOL was provided using only a 2-point fixation. Intraoperative position adjustment of the IOL provided an excellent centralization of multifocal IOL.

  8. Y-piece temperature and humidification during mechanical ventilation.

    Science.gov (United States)

    Solomita, Mario; Daroowalla, Feroza; Leblanc, Deniese S; Smaldone, Gerald C

    2009-04-01

    Practitioners often presume there is adequate humidification in the ventilator circuit if the Y-piece is at a specified temperature, but control of Y-piece temperature may be inadequate to ensure adequate humidification. In an in vitro bench model we measured water-vapor delivery with several heated humidification setups and a wide range of minute volume (V (E)) values. The setup included a condenser, hygrometry, and thermometer. First, we calibrated the system with a point-source humidifier and water pump. Then we tested the water-vapor delivery during non-heated-wire humidification and during heated-wire humidification with a temperature gradient of +3 degrees C, 0 degrees C, and -3 degrees C between the humidifier and the Y-piece. We compared the results to 2 recommended humidification values: 100% saturated (absolute humidity 44 mg H(2)O/L) gas at 37 degrees C (saturated/37 degrees C); and 75% saturated (absolute humidity 33 mg H(2)O/L), which is the humidity recommended by the International Organization for Standardization (the ISO standard). In all the experiments the setup was set to provide 35 degrees C at the Y-piece. Our method for measuring water-vapor delivery closely approximated the amount delivered by a calibrated pump, but slightly underestimated the water-vapor delivery in all the experiments and the whole V (E) range. At all V (E) values, water-vapor delivery during non-heated-wire humidification matched or exceeded saturated/37 degrees C and was significantly greater than that during heated-wire humidification. During heated-wire humidification, water-vapor delivery varied with the temperature gradient and did not reach saturated/37 degrees C at V (E) > 6 L/min. Water-vapor delivery with the negative temperature gradient was below the ISO standard. Maintaining temperature at one point in the inspiratory circuit (eg, Y-piece), does not ensure adequate water-vapor delivery. Other factors (humidification system, V (E), gradient setting) are critical

  9. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Directory of Open Access Journals (Sweden)

    Guerino Paolantoni

    2016-01-01

    Full Text Available The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces; in 45 cases the restoration was a screw-retained restoration (one piece. Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  10. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Science.gov (United States)

    Paolantoni, Guerino; Marenzi, Gaetano; Blasi, Andrea; Mignogna, Jolanda; Sammartino, Gilberto

    2016-01-01

    The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces); in 45 cases the restoration was a screw-retained restoration (one piece). Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results. PMID:27027093

  11. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region.

    Science.gov (United States)

    Paolantoni, Guerino; Marenzi, Gaetano; Blasi, Andrea; Mignogna, Jolanda; Sammartino, Gilberto

    2016-01-01

    The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces); in 45 cases the restoration was a screw-retained restoration (one piece). Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  12. A simple technique of intraocular lenses explantation for single-piece foldable lenses

    Directory of Open Access Journals (Sweden)

    Arup Bhaumik

    2017-01-01

    Full Text Available Foldable intraocular lenses (IOLs are most commonly used in modern-day cataract surgery. Explantation of these IOLs is not frequently encountered, but sometimes extreme situations may demand the same. Commonly explantation is achieved by bisecting the IOL inside the anterior chamber with a cutter and delivering the pieces out one by one. This may require corneal wound extension with associated damage and endothelial loss leading to visual deterioration. We devised a simple, innovative IOL explantation technique utilizing a modified Alcon A cartridge and snare. This can successfully refold the IOL to be explanted inside the eye and deliver it out through the same wound. The device has limitations with very thick optic lenses, multipiece, and silicon IOLs. In conclusion, we describe a simple, innovative, and reproducible technique to explant almost any single piece IOL without compromising the original surgery and yielding very satisfactory outcomes.

  13. Detection of kinetic change points in piece-wise linear single molecule motion

    Science.gov (United States)

    Hill, Flynn R.; van Oijen, Antoine M.; Duderstadt, Karl E.

    2018-03-01

    Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.

  14. Single-piece maintenance procedures for the TITAN reversed-field pinch reactor

    International Nuclear Information System (INIS)

    Grotz, S.P.; Creedon, R.L.; Cooke, P.I.H.; Duggan, W.P.; Krakowski, R.A.; Najmabadi, F.; Wong, C.P.C.

    1987-01-01

    The TITAN reactor is a compact (major radius of 3.9 m and minor plasma radius of 0.6 m), high neutron wall loading (--18MW/m 2 ) fusion energy system based on the reversed-field pinch (RFP) concept. The TITAN-I fusion power core (FPC) is a lithium, self-cooled design with vanadium alloy (V-3Ti-1Si) structural material. The compact design of the TITAN fusion power core (FPC) reduces the system to a few small and relatively low mass components, making toroidal segmentation of the FPC unnecessary. A single-piece maintenance procedure in which the replaceable first wall and blanket is removed as a single unit is, therefore, possible. The TITAN FPC design provides for top access to the reactor with vertical lifts used to remove the components. The number of remote handling procedures is few and the movements are uncomplicated. The annual torus replacement requires that the reusable ohmic-heating coil set and hot-shield assembly be removed and temporarily stored in a hot cell. The used first wall and blanket assembly is drained and disconnected from the coolant supply system, then lifted to a processing room where it is cooled and prepared for Class-C waste burial. The new, pre-tested first wall and blanket assembly is then lowered into position and the removal procedure is reversed to complete the replacement process

  15. Clinical properties of a novel, glistening-free, single-piece, hydrophobic acrylic IOL

    Directory of Open Access Journals (Sweden)

    Packer M

    2014-02-01

    Full Text Available Mark Packer,1 Mohan Rajan,2 Edoardo Ligabue,3 Peter Heiner4 1Oregon Health and Science University, Portland, OR, USA; 2Rajan Eye Care Hospital Pvt Ltd, Chennai, India; 3Ophthalmology Department, Centro Diagnostico Italiano, Milan, Italy; 4Bond University Medical School, Robina, QLD, Australia Abstract: A new, single-piece, hydrophobic acrylic lens – the first constructed with a lens optic and haptics comprised of a hydroxyethyl methacrylate-polyethylene glycol phenyl ether acrylate–styrene copolymer, cross-linked with ethylene glycol dimethacrylate, and labeled as "glistening-free" – was recently introduced globally. Glistenings have been a significant source of clinical concern with previous hydrophobic lens designs. This new monofocal lens provides enhanced, clear optics for lens-based surgery. The superior optical clarity of this lens is achieved through the elimination of glistenings, enhanced surface durability, high refractive index, a high Abbe number, and an aspheric design. Additionally, the lens design reduces the risk of developing posterior capsule opacification. Keywords: glistenings, monofocal hydrophobic acrylic, IOL, aspheric

  16. Mechanical Processing of GFRP Waste into Large-Sized Pieces for Use in Concrete

    Directory of Open Access Journals (Sweden)

    Ardavan Yazdanbakhsh

    2018-02-01

    Full Text Available Recycling glass fiber reinforced polymer (GFRP composite materials has been proven to be challenging due to their high mechanical performance and high resistance to harsh chemical and thermal conditions. This work discusses the efforts made in the past to mechanically process GFRP waste materials by cutting them into large-sized (cm scale pieces, as opposed to pulverization, for use in concrete mixtures. These pieces can be classified into two main categories—coarse aggregate and discrete reinforcement, here referred to as “needles.” The results from all the studies show that using GFRP coarse aggregate leads to significant reductions in the compressive strength and tensile strength of concrete. However, GFRP needles lead to sizable increases in the energy absorption capacity of concrete. In addition, if the glass fibers are longitudinally aligned within the needles, these elements can substantially increase the tensile strength of concrete. Processing GFRP waste into needles requires less energy and time than that for producing GFRP coarse aggregate. Also, compared to pulverized GFRP waste, which consists of broken and separate particles of glass and resin that at best can be used as low-quality fillers, GFRP needles are high strength composite elements.

  17. Retrospective Study of Tapered One-Piece Implants Placed Over a Ten-Year Period in a Single Private Practice.

    Science.gov (United States)

    Minichetti, John C; D'Amore, Joseph C; Hong, Anna Y-J

    2018-04-01

    Today, clinicians have a variety of treatment modalities available to address the increasing number of implant procedures performed each year. Single-stage implant surgery is now commonly used in implant dentistry. With patients' demands for immediate restoration, the utilization of 1-piece implants is gaining acceptance. This article reports the results of tapered 1-piece implants (Zimmer Biomet) placed in a single practice over a 10-year period. A total of 33 1-piece dental implants were placed in 24 patients and provisionally restored out of occlusion at the time of surgery. All 33 implants were definitively restored with ceramometal crowns after 3 months of provisionalization. Implant survival and success rates were 100% after 2.6-10 years of follow-up. Only 1 minor complication of crestal bone remodeling occurred among the 33 implants placed. Adequately stabilized tapered 1-piece implants can be successfully restored out of occlusion at the time of implant placement and definitively loaded in occlusion 3 months without adversely affecting function or esthetics. Additional long-term controlled studies are recommended to further understand these findings.

  18. Flow requirements and rebreathing during mechanically controlled ventilation in a T-piece (Mapleson E) system.

    Science.gov (United States)

    Hatch, D J; Yates, A P; Lindahl, S G

    1987-12-01

    The influence of fresh gas flow (FGF) setting on rebreathing was investigated in 15 infants and children (weight 3.5-21.8 kg) during balanced anaesthesia with mechanically controlled ventilation using a T-piece (Mapleson E) system and a Nuffield ventilator 200. Tidal volume (VT), minute volume (VE), maximal inspired (PICO2) and end-tidal (PE'CO2) carbon dioxide tensions and airway pressure were measured. VE, set to produce a PE'CO2 of about 4.5 kPa and measured at a high FGF (minimal rebreathing), was unchanged throughout the study and the regression equation for VE and weight was: VE (ml min-1) = 146 x kg + 482, r = 0.92. Measurements were then repeated at FGF:VE ratios reduced to 1.5 and 1.0. To achieve minimal rebreathing (PICO2 less than 0.5 kPa), FGF:VE ratios greater than 1.8 (range 1.8-4.9) had to be used. At FGF:VE ratios of 1.5, some alveolar rebreathing occurred, indicated by increased inspired (P less than 0.001) and end-tidal (P less than 0.001) carbon dioxide tensions. At FGF:VE ratios equal to 1.0, alveolar rebreathing was more pronounced and hypercapnoea occurred with a PE'CO2 (mean +/- 1 SD) of 5.89 +/- 0.53 kPa. At this FGF setting, change in I:E ratio from 1:2 to 1:1 did not influence the level of alveolar rebreathing. A minimal FGF (ml min-1) setting of 1.5 x VE (that is, 1.5 (146 x kg + 482), approximated to the expression (200 x kg + 1000) is recommended for controlled ventilation to avoid hypercapnoea when using the T-piece system in children weighing less than 20 kg.

  19. Influence of use of ultrasound on the mechanical properties of plated pieces by welding in ultrasonic field

    Directory of Open Access Journals (Sweden)

    Gh. Amza

    2015-07-01

    Full Text Available Plating by welding in an ultrasonic field represents a technological solution to increase resistance to corrosion and / or wear of pieces of the machinery industry. Research has been carried out for two types of parts, namely a piece of flange end type and bonnet type made of AISI 4130 steel, and as filler material for plating was used Inconel 625 Fe developed as electrode wire with a diameter of ø 1.2 / mm. The plating was done by depositing a single layer by welding in ultrasonic field, welding process in Ar 100/ % environment non-consumable tungsten electrode, WIG process, and when using ultrasonic activation it was used a longitudinal and a transverse wave with a frequency of 15 / kHz. For pieces plated by welding there have been made attempts of the hardness and tensile and bend shock.

  20. One-piece zirconia oral implants: one-year results from a prospective cohort study. 1. Single tooth replacement.

    Science.gov (United States)

    Kohal, Ralf-Joachim; Knauf, Marko; Larsson, Birgitta; Sahlin, Herman; Butz, Frank

    2012-06-01

    To investigate the clinical and radiographic outcome of a one-piece zirconia oral implant for single tooth replacement after 1 year. A total of 65 patients received a one-stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion and after 1 year to monitor peri-implant bone loss. A univariate analysis of the influence of different baseline parameters on marginal bone loss from implant insertion to 12 months was performed. Soft tissue parameters were evaluated at prosthesis insertion and at the 1-year follow-up. After 1 year, three implants were lost, giving a cumulative survival rate of 95.4%. The marginal bone loss after 1 year was 1.31 mm. Thirty-four per cent of the implants lost at least 2 mm bone, and 14% more than 3 mm. The univariate analysis could not depict any parameter influencing marginal bone loss. Probing depth, Clinical Attachment Level, Bleeding and Plaque Index decreased over 1 year. The cumulative survival rate of the presented ceramic implant was comparable to the reported survival rate of titanium implants when immediately restored. However, the frequency of increased radiographic bone loss (>2 mm) after 1 year was considerably higher as compared to conventional two-piece titanium implants. The presented zirconia implant can therefore not be recommended for clinical usage. © 2012 John Wiley & Sons A/S.

  1. Mechanical Performance Evaluation of a Top End Piece for Dual Cooled Fuels

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Kim, Hyung Kyu; Choi, Woo Seok

    2011-01-01

    A fuel assembly consists of five major components, i.e., a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT): in addition, it also includes fuel rods (FRs). The TEP/BEP should satisfy stress intensity limits according to the conditions A and B of ASME, Section III, Division 1.Subsection NB. In a dual-cooled fuel assembly, the array and position of fuel rods are different from those in a conventional PWR fuel assembly; these changes are necessary for achieving power uprating. The flow plates of the TEP and BEP have to be modified accordingly. The pattern and shape of the flow holes were newly designed. To verify the strength compatibility, the Tresca stress limit according to the ASME code was investigated in the case of an axial load of 22.241 kN. In this paper, the stress linearization procedure for strength evaluation of a newly designed TEP is presented

  2. Far infrared spectroscopy of Ge film deposited on a piece of Si wafer and single crystal Ge

    International Nuclear Information System (INIS)

    Roslan, M.; Ibrahim, K.; Wan Abdullah, A.K.

    1991-01-01

    The far infrared spectrum of thin polycrystalline film of Ge of approximately 10 μm deposited on a piece of Si wafer (99.99% purity) has been obtained using the far infrared Fourier transform spectroscopy system developed recently in our laboratory. The spectrum of Ge film from 180 to 480 cm -1 obtained after rationing against Si wafer spectrum at a resolution of about 1 cm -1 has been obtained. It is interesting to note that this thin film of Ge is extremely transparent to radiation in this region and phonon absorption processes as reported previously could not be observed due to thinness of the film. The spectrum of a single crystal of Ge (99.9% purity) and Ge-doped Li have revealed several absorption bands which we have assigned as due to 2-phonon and 3-phonon processes in Ge. The bands at 195, 273 and 287 cm -1 could not be assigned as phonon processes and at present we do not know the causes of these absorption bands

  3. Safety and effectiveness of a glistening-free single-piece hydrophobic acrylic intraocular lens (enVista)

    Science.gov (United States)

    Packer, Mark; Fry, Luther; Lavery, Kevin T; Lehmann, Robert; McDonald, James; Nichamin, Louis; Bearie, Brian; Hayashida, Jon; Altmann, Griffith E; Khodai, Omid

    2013-01-01

    Purpose To evaluate the safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (IOL; enVista model MX60; Bausch & Lomb, Rochester, NY, USA) when used to correct aphakia following cataract extraction in adults. Methods This was a prospective case series (NCT01230060) conducted in private practices in the US. Eligible subjects were adult patients with age-related cataract amenable to treatment with standard phacoemulsification/extracapsular cataract extraction. With follow-up of 6 months, primary safety and effectiveness end points included the rates of US Food and Drug Administration (FDA)-defined cumulative and persistent adverse events and the percentage of subjects who achieved best-corrected visual acuity (BCVA) of 20/40 or better at final visit. To evaluate rotational stability, subjects were randomized (1:1:1:1) to have the lens implanted in one of four axis positions in 45° increments. Results A total of 122 subjects were enrolled. The rate of cumulative and persistent adverse events did not significantly exceed historical controls, as per FDA draft guidance. At the final postoperative visit, all subjects (100%) achieved a BCVA of 20/40 compared with the FDA historical control of 96.7%. Rotation of the IOL between the two final follow-up visits was ≤5° for 100% of eyes, and refractive stability was demonstrated. A low evaluation of posterior capsule opacification score was demonstrated, and no glistenings of any grade were reported for any subject at any visit. Conclusion This study demonstrated the safety and effectiveness of the MX60 IOL. Favorable clinical outcomes included preserved BCVA, excellent rotational and refractive stability, no glistenings, and a low evaluation of posterior capsule opacification score. PMID:24109169

  4. Three pieces

    OpenAIRE

    Palomas Pubill, Alejandro

    1992-01-01

    The following Master's Thesis represents the culmination of two years' work in the UCSD department of music. The three pieces, Bicusp[i think you've got]id, Sequitur, non?, and Solo for horn, appear in order of completion, the first two having been composed for juries, the last for a fellow student's recital. My efforts in composition during the program have focused on the exploration of chaotic states, energy transfer, transformative trajectories, and non-traditional sound worlds. One can se...

  5. Safety and effectiveness of a glistening-free single-piece hydrophobic acrylic intraocular lens (enVista

    Directory of Open Access Journals (Sweden)

    Packer M

    2013-09-01

    Full Text Available Mark Packer,1 Luther Fry,2 Kevin T Lavery,3 Robert Lehmann,4 James McDonald,5 Louis Nichamin,6 Brian Bearie,7,† Jon Hayashida,8 Griffith E Altmann,8 Omid Khodai8 1Department of Ophthalmology, Oregon Health and Science University, Eugene, OR, USA; 2University of Kansas Medical Center, Kansas City, KS, USA; 3Wayne State University, Detroit, MI, USA; 4Baylor College of Medicine, Houston, TX, USA; 5University of Arkansas for Medical Sciences, Little Rock, AR, USA; 6Laurel Eye Clinic, Brookville, PA, USA; 7Grand Rapids Eye Institute, Grand Rapids, MI, USA; 8Bausch & Lomb, Aliso Viejo, CA, USA †Brian Bearie passed away on March 9, 2011 Purpose: To evaluate the safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (IOL; enVista model MX60; Bausch & Lomb, Rochester, NY, USA when used to correct aphakia following cataract extraction in adults. Methods: This was a prospective case series (NCT01230060 conducted in private practices in the US. Eligible subjects were adult patients with age-related cataract amenable to treatment with standard phacoemulsification/extracapsular cataract extraction. With follow-up of 6 months, primary safety and effectiveness end points included the rates of US Food and Drug Administration (FDA-defined cumulative and persistent adverse events and the percentage of subjects who achieved best-corrected visual acuity (BCVA of 20/40 or better at final visit. To evaluate rotational stability, subjects were randomized (1:1:1:1 to have the lens implanted in one of four axis positions in 45° increments. Results: A total of 122 subjects were enrolled. The rate of cumulative and persistent adverse events did not significantly exceed historical controls, as per FDA draft guidance. At the final postoperative visit, all subjects (100% achieved a BCVA of 20/40 compared with the FDA historical control of 96.7%. Rotation of the IOL between the two final follow-up visits was ≤5° for 100% of eyes, and refractive

  6. Alveolar Bone Resorption Evaluation Around Single-piece Designed Bicortical Implants, Using Immediate Loading Protocol, Based on Orthopantomographs

    Directory of Open Access Journals (Sweden)

    Száva Dániel-Tamás

    2017-12-01

    Full Text Available Background: Inserting dental implants in severely atrophied jawbones is a great challenge for the dental practitioner. There are an increasing number of patients who choose dental implantanchored prosthetic restorations despite compromised bone quality and quantity. There have been numerous attempts in adapting implant design for the atrophic crestal bone. One-piece, needle-type basal implant design is a typical design for these cases. These implants are inserted in the remaining compact bone located in the basal aspect of the jawbones. If high primary stability is achieved, these implants are used for immediate loading protocol. From many points of view, this technique is based on contradictory principles compared to classic implant surgery and loading protocols. The aim of this study was to investigate the long-term success of basal one-piece short-diameter dental implants used for immediate loading protocol.

  7. Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children.

    Science.gov (United States)

    Terada, Y; Kono, S; Ishizawa, K; Inamura, S; Uchiumi, T; Tamada, D; Kose, K

    2013-05-01

    We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. One-piece internal zirconia abutments for single-tooth restorations on narrow and regular diameter implants: A 5-year prospective follow-up study.

    Science.gov (United States)

    Nilsson, Andrée; Johansson, Lars-Åke; Lindh, Christina; Ekfeldt, Anders

    2017-10-01

    Studies have reported an increased risk for fractures of zirconia abutments compared with titanium abutments. The aim of this study was to evaluate single-tooth implant restorations with one-piece yttria-stabilized internal zirconia abutments on narrow and regular diameter implants up to 6 years after insertion. This study comprises 52 consecutively treated patients, with a median age of 19 years. In total, 59 narrow (3.3 mm) and 10 regular (4.1 mm) diameter implants were installed. Sixty-five all-ceramic crowns were cemented on implant-supported one-piece internal zirconia abutments and 4 restorations were screw-retained. Thirty-five patients with 48 implant restorations participated in the final examination and another 14 patients with 16 implant restorations were possible to reach and could be interviewed. The implant survival was 100% but the survival rate for the implant-supported ceramic restorations was lower, 87.5%. Three crowns (4.7%) were remade for different reasons. Five restorations (7.8%) were remade due to fracture of the internal one-piece zirconia abutment. Four of these fractures occurred in 3.3 mm implant abutments. Narrow diameter implants offer an opportunity to restore small single-tooth edentulous gaps. For esthetical reasons the choice of an abutment in zirconia can be favorable, but at least with the used implant system, there seems to be an increased risk for fracture. Most patients were very satisfied with the esthetics and function of their implant restorations. © 2017 Wiley Periodicals, Inc.

  9. Single banking supervision and the single supervisory mechanism

    Directory of Open Access Journals (Sweden)

    Gheorghe, C. A.

    2013-06-01

    Full Text Available A resolution seems to have been found for the banking crisis. The first steps have been made towards the construction of the Economic and Monetary Union, steps involving the single supervision of banks, in order to avoid the discount of a new financial crisis on the expense of the EU state members. The Single Supervisory Mechanism – SSM is to become effective as of March 1, 2014, at the earliest.

  10. Evaluation of a one-piece ceramic implant used for single-tooth replacement and three-unit fixed partial dentures: a prospective cohort clinical trial.

    Science.gov (United States)

    Jung, Ronald E; Grohmann, Philipp; Sailer, Irena; Steinhart, Yann-Niclas; Fehér, Aurel; Hämmerle, Christoph; Strub, Jörg Rudolf; Kohal, Ralf

    2016-07-01

    The aim of this clinical trial was to evaluate the safety and efficiency of a one-piece zirconia oral implant after 1 year of function. Two centers included 60 subjects in need of implant-supported single-tooth restorations or three-unit bridges. A total of 71 zirconia one-piece implants were placed and immediately restored with a temporary reconstruction for at least 2 months. The final veneered zirconia restorations were then cemented and followed for 6 months and 1 year after insertion of the restorations. At each visit, a clinical evaluation was performed to analyze biological parameters of the implants and the neighboring teeth. A standardized periapical radiograph was taken at implant insertion, at the placement of the restorations and at the 1-year follow-up. Sixty patients with 71 implants (48 in the mandible, 23 in the maxilla) were included in this study and provided with 11 bridges and 49 crowns. Two patients with three implants (one bridge and one single crown) could not be evaluated. One patient lost his implant 5 weeks after implant insertion. Based on 58 patients, the mean survival rate was 98.3% after one year when the implants of the two patients that did not show up were not counted as lost. The mean marginal bone loss from implant insertion to the 1-year follow-up after the final prosthetic restoration was 0.78 mm with a standard deviation of 0.79 mm. The probing depth around the implants increased from 2.7 mm at insertion of the prosthetic reconstruction to 3.5 mm one year after insertion. The probing depth around the adjacent teeth remained stable at 2.5 mm. At the 1-year recall, the difference was significant. The clinical attachment levels at implants and teeth were not different at the 1-year follow-up with 3.1 mm at tooth and implant sites. The presently tested one-piece ceramic implant was successful in replacing single tooth and three-unit gaps after one year of function. Further long-term data are necessary to verify these

  11. Early Loading of Single-Piece Implant for Partially Edentulous Posterior Arch: A Prospective One-Year Case Report

    Directory of Open Access Journals (Sweden)

    Amol Beldar

    2013-01-01

    Full Text Available Implant therapy is now well established, and there is an increasing need for shorter rehabilitation time. Original prerequisites of osseointegration have been reassessed to satisfy continuously increasing patient's expectation of reduced treatment time, improved esthetics, and increased comfort. Shorter healing time may be appropriate in some circumstances, and examples of early loading have been reported in animal and human studies. However, to date there are insufficient data to determine a universally acceptable opinion on early loading of implants for single-tooth replacement. This case report involves early loading, combined with construction of a restoration, inserted directly after 6 weeks of implant surgery and followup of one year.

  12. Early Loading of Single-Piece Implant for Partially Edentulous Posterior Arch: A Prospective One-Year Case Report

    Science.gov (United States)

    Beldar, Amol; Bhongade, Manohar L.; Byakod, Girish; Buregoni, Chandrashekar

    2013-01-01

    Implant therapy is now well established, and there is an increasing need for shorter rehabilitation time. Original prerequisites of osseointegration have been reassessed to satisfy continuously increasing patient's expectation of reduced treatment time, improved esthetics, and increased comfort. Shorter healing time may be appropriate in some circumstances, and examples of early loading have been reported in animal and human studies. However, to date there are insufficient data to determine a universally acceptable opinion on early loading of implants for single-tooth replacement. This case report involves early loading, combined with construction of a restoration, inserted directly after 6 weeks of implant surgery and followup of one year. PMID:23710375

  13. Continuum mechanics of single-substance bodies

    CERN Document Server

    Eringen, A Cemal

    1975-01-01

    Continuum Physics, Volume II: Continuum Mechanics of Single-Substance Bodies discusses the continuum mechanics of bodies constituted by a single substance, providing a thorough and precise presentation of exact theories that have evolved during the past years. This book consists of three parts-basic principles, constitutive equations for simple materials, and methods of solution. Part I of this publication is devoted to a discussion of basic principles irrespective of material geometry and constitution that are valid for all kinds of substances, including composites. The geometrical notions, k

  14. Mechanical Properties Of Single Crystal Ceramics

    Science.gov (United States)

    Rowcliffe, D. J.; Johnson, S. M.

    1987-03-01

    Approaches to characterizing the mechanical behavior of single crystal ceramics are reviewed. Consideration is given to techniques applicable to large crystals and to indentation techniques that can be used on crystals of 1 mm or less. The importance of flaws in controlling the mechanical behavior of brittle ceramics is discussed, leading to an emphasis on fracture mechanics methods. These techniques are applicable to the determination of fracture toughness and to the measurement of slow crack growth in aggresive environments. Indentation processes have been analyzed extensively and the good understanding of stress fields and micro-mechanics of indentation has led to techniques to measure hardness, toughness and elastic modulus. Measurements of hardness anistropy can be used to determine slip planes and also provide considerable information on local plastic flow in brittle crystals.

  15. One-piece zirconia oral implants for single-tooth replacement: Three-year results from a long-term prospective cohort study.

    Science.gov (United States)

    Kohal, Ralf-Joachim; Spies, Benedikt C; Bauer, Annalena; Butz, Frank

    2018-01-01

    This 3-year report of a prospective long-term cohort investigation aimed to evaluate the clinical and radiographic outcomes of a one-piece zirconia oral implant for single-tooth replacement. Sixty-five patients received a 1-stage implant surgery with immediate temporization. Standardized radiographs were taken at implant insertion, after 1 year, and after 3 years to monitor peri-implant bone levels. A univariate analysis of the association of different baseline parameters on marginal bone loss from implant insertion to 36 months was performed. Soft-tissue parameters were evaluated at prosthesis insertion, after 6 months, after 1 year, and at the 3-year follow-up. After 3 years, six posterior site implants were lost, giving a cumulative survival rate of 90.8%. The mean marginal bone loss was 1.45 mm; 35% of the implants lost at least 2 mm bone, and 22% more than 3 mm. The univariate analysis did not identify any parameter associated with marginal bone loss. Probing depth, clinical attachment level, and bleeding index increased over 3 years, and plaque index decreased. The low survival rate of the presented ceramic implant and especially the high frequency of advanced bone loss are noticeable but remain unexplained. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. The Up-to-14-Year Survival and Complication Burden of 256 TiUnite Implants Supporting One-Piece Cast Abutment/Metal-Ceramic Implant-Supported Single Crowns.

    Science.gov (United States)

    Walton, Terry R

    To assess the estimated cumulative survival (ECS) and explore the technical and biologic complications of 256 TiUnite implants (Nobel Biocare) supporting one-piece cast abutment/metal-ceramic implant-supported single crowns (ISCs) in situ for up to 14 years. A prospective sequentially recruited cohort of 207 patients received 256 metal-ceramic ISCs on TiUnite implants between 2001 and 2014. All but 24 patients with 27 crowns were clinically evaluated between January 2014 and April 2015 in conjunction with or in addition to their tailored maintenance program. Radiographs were obtained, and any previously recorded treatments associated with the crowns were tabulated. The ECS and standard errors were calculated with the life table actuarial method and Greenwood's formula, respectively. The log rank test was applied to assess differences between anterior and posterior crowns. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. Independent groups were compared with the Mann-Whitney U test and related groups with the Wilcoxon Signed Rank Test. The mean clinical service time of the crowns was 5.61 years (44 ≥ 10 years). The 14-year ECS was 95.95% ± 3.20% with no significant difference between anterior and posterior prostheses. Only seven implants lost marginal bone ≥ one thread from the time of crown insertion. There were 30 nonterminal complications (16 biologic, 14 mechanical). The associated economic burden was low (n = 35 TAUs). High gold-alloy one-piece cast abutment/metal-ceramic ISCs on TiUnite implants exhibited excellent longevity and few complications over 14 years.

  17. Transition piece for joining together tubular pieces

    International Nuclear Information System (INIS)

    Holko, K.H.

    1981-01-01

    A transition piece for joining together tubular pieces formed respectively from a low alloy or carbon steel and a high temperature alloy containing at least 16% chromium includes a plurality of tubular parts welded together and formed from materials of selected composition with a maximum chromium content difference of 5% between adjacent parts when the chromium content of each part is below 10% and a maximum chromium difference of 7% between adjacent parts when the chromium content of either part is above 10%. The transition parts are also graded as to such characteristics as thermal expansion coefficient. The transition parts at opposite ends of the transition joint have chromium percentages similar to the tubular pieces to which they are to be joined. The parts may be joined by fusion and/or friction welding and parts may be formed by fusion weld deposition. (author)

  18. Analysis of crestal bone loss around single piece ball attachment implant placed bilaterally in canine region and wear of O-ring in implant supported overdenture: Three year follow-up.

    Science.gov (United States)

    Raza, Fathima Banu; Vaidyanathan, Anand Kumar; Veeravalli, Padmanabhan T; Ravishankar, Subhiksha; Ali, Aashique S

    2018-03-06

    Single piece implant in fixed prosthesis is widely been evaluated, however, long term evaluation of crestal bone loss and the wear of O-ring in single piece ball attachment implant supported overdenture is yet to be evaluated PURPOSE: The present article evaluates the crestal bone loss around single piece ball attachment implants placed bilaterally in the canine region and the wear of O-ring in implant supported overdenture over a period of three years. Twelve completely edentulous patients between the age group of 55-65 years were selected. Two 3.3 mm × 13 mm myriad snap fit implants were placed in the mandibular interforaminal region. All the implants were conventionally loaded at three months after surgical placement. Intra-oral periapical radiographs were made and crestal bone loss was measured at the end of one year and three years. The elasticity and wear of O-Ring was assessed after three years of usage. The crestal bone loss showed no significant difference between the first and third year after implant placement. The mean bone loss at the end of third year was 1.5 mm. Analysis of O-ring for change in the elasticity showed reduction in displacement and a significant increase in maximum displacement and elongation. The area of O-ring and yield stress did not show any changes from the standard value. Compression set damage was observed in the O-ring at the end of three years. The present study shows that the bilateral single piece implant supported overdenture has a success rate equivalent to the two piece implant supported overdenture and is a viable treatment option. © 2018 Wiley Periodicals, Inc.

  19. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...... and a preferred direction of switching as function of STM tip position. Based on first principles calculations, are show that this behaviour is due to a novel mechanism involving an electronic excitation of a localized surface resonance. (C) 1998 Elsevier Science B.V. All rights reserved....

  20. Single-ion nonlinear mechanical oscillator

    International Nuclear Information System (INIS)

    Akerman, N.; Kotler, S.; Glickman, Y.; Dallal, Y.; Keselman, A.; Ozeri, R.

    2010-01-01

    We study the steady-state motion of a single trapped ion oscillator driven to the nonlinear regime. Damping is achieved via Doppler laser cooling. The ion motion is found to be well described by the Duffing oscillator model with an additional nonlinear damping term. We demonstrate here the unique ability of tuning both the linear as well as the nonlinear damping coefficients by controlling the laser-cooling parameters. Our observations pave the way for the investigation of nonlinear dynamics on the quantum-to-classical interface as well as mechanical noise squeezing in laser-cooling dynamics.

  1. Composition: 3 Piano Pieces

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2017-01-01

    3 Piano Pieces is a collection of open composition to be realised by an improvising pianist. See more about my composition practise in the entry "Composition - General Introduction".......3 Piano Pieces is a collection of open composition to be realised by an improvising pianist. See more about my composition practise in the entry "Composition - General Introduction"....

  2. One-piece implants: placement timing, surgical technique, loading protocol, and marginal bone loss.

    Science.gov (United States)

    Prithviraj, D R; Gupta, Vikas; Muley, Ninad; Sandhu, Pushpinder

    2013-04-01

    Osseointegration being an accepted and well-documented concept, attention is now directed towards simplification of the mechanical design of implants and towards achieving biomechanical success. The aim of this literature review is to provide an overview of the one-piece implant, with its advantages and disadvantages over a conventional two-piece implant. The PubMed database was searched in the English language using the keywords one-piece implant, single-piece implant, single-stage implant surgery, and two-piece implant. Articles were selected on the basis of whether they had sufficient information related to placement timing, surgical procedure used, loading protocol, follow-up periods, marginal bone loss, and implant success rates of one-piece implants. For inclusion, a study group must have had a minimum of 30 one-piece implants followed for at least 1 year. Nineteen articles were subjected to the selection criteria. Out of 19 clinical trials only 11 met the selection criteria. Five parameters were taken into consideration for studying one-piece implants: placement timing, surgical technique, loading protocol, marginal bone loss, and implant survival rate. The data from the identified studies were tabulated according to these parameters and discussed. Delayed placement of one-piece implants is more commonly practiced than extraction and immediate placement. Most surgeons prefer surgeries using flaps as compared to flapless surgeries, and in most cases, one-piece implants were loaded immediately. Limited literature reveals both positive and negative results regarding the effect of a one-piece implant system on surrounding hard and soft tissues. © 2012 by the American College of Prosthodontists.

  3. Extracorporeal CO2 removal--a way to achieve ultraprotective mechanical ventilation and lung support: the missing piece of multiple organ support therapy.

    Science.gov (United States)

    Gramaticopolo, Silvia; Chronopoulos, Alexandra; Piccinni, Pasquale; Nalesso, Federico; Brendolan, Alessandra; Zanella, Monica; Cruz, Dinna N; Ronco, Claudio

    2010-01-01

    Extracorporeal therapies are able to sustain life through different mechanisms. This approach, called multiple organ support therapy, can in fact obtain blood purification by hemodialysis/hemofiltration to replace kidney function, temperature control, electrolyte and acid-base control to mimic homeostatic regulation of the kidney and circulation, fluid balance control to support the right hydration and cardiac performance, cardiac support removing cardiodepressant substances and equilibrating potassium levels, blood detoxification and liver support by coupled plasma filtration and adsorption or direct adsorption on blood (hemoperfusion), immunomodulation and endothelial support in the presence of sepsis by cutting the peaks of pro- and anti-inflammatory mediators, and immunoadsorption or adsorption of specific substances such as endotoxin. A missing piece of this group of therapies was the protective lung support. Today this is made possible by removal of CO(2) either by complete extracorporeal membrane oxygenation or by using decapneization in conjunction with hemofiltration in a system called DECAP/DECAPSMART. In conclusion, circulating blood outside the body and treating it with different filters or cartridges in a multiple organ support therapy may represent an important support for multiple organ dysfunction conditions induced by sepsis, acute respiratory distress syndrome and in recent times by complicated H1N1-related infections. 2010 S. Karger AG, Basel.

  4. RETURNED FOOT EXTERIOR CHORD BROOCHES MADE OF A SINGLE METAL PIECE (TYPE ALMGREN 158 RECENTLY DISCOVERED IN THE WESTERN PLAIN OF ROMANIA.

    Directory of Open Access Journals (Sweden)

    Vitalie Bârcă

    2014-07-01

    Full Text Available This study, without aiming at exhaustiveness, attempts, based on returned foot exterior chord brooches made of a single metal pieces (type Almgren 158 discovered in 2010 following the rescue archaeological excavations performed as a result of the construction of the Arad-Timişoara Highway, respectively section Arad-Seceani, in a series of Sarmatian graves of the cemetery investigated at Hunedoara Timișană, Șagu commune, Arad county, to analyse the brooches in this type discovered in the western territories of Romania.The author examines the four specimens at Hunedoara Timișană within a broader context and concludes that similar brooches in both the Barbarian and Roman environments, where they are imports, date mainly to the chronological interval comprised between the last two decades of the 2nd c. – early 4th c. AD (stages C1a-C2.The analysis of the graves in the cemetery showed that the graves where returned foot exterior chord brooches were found date sometime in the chronological interval comprised between the end of the 2nd c. AD and the third quarter of the 3rd c. AD. Moreover, the author notes that the distribution area of this brooch type is mainly the Barbarian world of German origin (the Przeworsk culture environment or that in constant contact with the latter. Based on the analysis of the distribution area of the Almgren 158 type brooches it was concluded they originate in the Przeworsk culture environment from where they disseminated in the neighbouring south and south-east cultural environments. Last but not least, the author reaches the conclusion that brooches of the type were assumed by the Sarmatians in the Pannonian Plain from the German populations (most likely the Vandals living in the northern vicinity of the area they inhabited. Another conclusion is that such returned foot exterior chord brooches are lacking from the north and north-west Pontic areas, including the Chernyakhov area. Finally, the author argues that

  5. Investigation of Chirality Selection Mechanism of Single Walled Carbon Nanotube

    Science.gov (United States)

    2016-12-13

    AFRL-AFOSR-JP-TR-2017-0007 Investigation of Chirality Selection Mechanism of Single -Walled Carbon Nanotube Seun Min Kim KOREA INSTITUTE OF SCIENCE...Selection Mechanism of Single -Walled Carbon Nanotube 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-15-1-4099 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR...research involved investigation of two fundamental mechanisms of carbon nanotube (CNT) growth: chirality selection of single -walled CNT (SWCNT) and

  6. Sigtuna Think Piece 8

    African Journals Online (AJOL)

    exploring how participatory social learning research may strengthen agency and reflexivity (development of capabilities) in response to socio-ecological conditions. Introduction: Thinking about Climate Change Critically in Context. This think piece emerged from a slow engagement with the topic of climate change and its.

  7. Wire inhomogeneity detector having a core with opposing pole pieces and guide pieces adjacent the opposing pole pieces

    International Nuclear Information System (INIS)

    Gibson, G.H.; Smits, R.G.; Eberhard, P.H.

    1989-01-01

    This patent describes a wire inhomogeneity detector assembly for detecting changes in the conductive properties of a wire as the wire is passed therethrough. It comprises: a coil assembly through which a wire containing conductive material is adapted to be pressed in a direction substantially perpendicular to a longitudinal axis of the coil assembly. The coil assembly comprising a single ferrite core having a pair of opposing pole pieces between which are an associated conductive wire to be tested is adapted to be passed, each of the pole pieces having a coil wound therearound. The coil assembly including a guide-block consisting of a pair of guide pieces mounted adjacent to ends of the opposing pole pieces for guiding an associated conductive wire between the pole pieces and for reducing stray magnetic field lines. The guide pieces being positioned closely adjacent an associated conductive wire passing therebetween; an impedance bridge adjusted to an null balance point operatively connected to the coil assembly which measures the impedance of the coil assembly and is unbalanced by changes in eddy currents generated in the coil assembly; and a filter detector alarm assembly operatively connected to an output of the impedance bridge. The filter detector alarm assembly including an input bandpass filter detector alarm assembly including an input bandpass filter operatively connected to a differential comparator, the output of which triggers an alarm

  8. Contribution de la logique floue à la représentation des dimensions des pièces d'un ensemble mécaniqueFuzzy logic contribution to the representation of mechanical assembly pieces

    Science.gov (United States)

    Lelu, Cédric; Dahan, Marc

    The cotation process of a mechanical assembly is a long and complex step of the design. The piece dimensions are often modeled with 2D vectors or torsors. A new representation based on fuzzy logic is presented in this article. The calculus methods of fuzzy dimensions are examined and an application to the extreme positions of a rod-crank system with uncertain dimensions is also presented. To cite this article: C. Lelu, M. Dahan, C. R. Mecanique 330 (2002) 133-140.

  9. Optimal mechanisms for single machine scheduling

    NARCIS (Netherlands)

    Heydenreich, B.; Mishra, D.; Müller, R.; Uetz, Marc Jochen; Papadimitriou, C.; Zhang, S.

    2008-01-01

    We study the design of optimal mechanisms in a setting here job-agents compete for being processed by a service provider that can handle one job at a time. Each job has a processing time and incurs a waiting cost. Jobs need to be compensated for waiting. We consider two models, one where only the

  10. Molecular mechanics applied to single-walled carbon nanotubes

    OpenAIRE

    Ávila,Antonio Ferreira; Lacerda,Guilherme Silveira Rachid

    2008-01-01

    Single-walled carbon nanotubes, with stiffness of 1.0 TPa and strength of 60 GPa, are a natural choice for high strength materials. A problem, however, arises when experimental data are compiled. The large variability of experimental data leads to the development of numerical models denominated molecular mechanics, which is a "symbiotic" association of molecular dynamics and solid mechanics. This paper deals with molecular mechanics simulations of single-walled carbon nanotubes. To be able to...

  11. Piece of the sun

    CERN Document Server

    Wayne, Teddy

    2015-01-01

    Our rapidly industrialising world has an insatiable hunger for energy, and conventional sources are struggling to meet demand. Oil is running out, coal is damaging our climate, many nations are abandoning nuclear, yet solar, wind and water will never be a complete replacement. The solution, says Daniel Clery in this deeply researched and revelatory book, is to be found in the original energy source: the Sun itself. There, at its centre, the fusion of 630 million tonnes of hydrogen every second generates an unfathomable amount of energy. By replicating even a tiny piece of the Sun's power

  12. Mechanical and microstructural characterization of single and double pass Aluminum AA6061 friction stir weld joints

    International Nuclear Information System (INIS)

    Othman, N H; Shah, L H; Ishak, M

    2015-01-01

    This study focuses on the effect of single pass (SP), double sided pass (DSP) and normal double pass (NDP) method on friction stir welding of aluminum AA6061. Two pieces of AA6061 alloy with thickness of 6 mm were friction stir welded by using conventional milling machine. The rotational speeds that were used in this study were 800 rpm, 1000 rpm and 1200 rpm, respectively. The welding speed is fixed to 100 mm/min. Microstructure observation of welded area was studied by using optical microscope. Tensile test and Vickers hardness test were used to evaluate the mechanical properties of this specimen. Mechanical property analysis results indicate that at low rotational speeds, defects such as surface lack of fill and tunneling in the welded area can be observed. Vickers hardness of specimens however did not vary much when rotational speed is varied. Welded specimens using single pass method shows higher tensile strength and hardness value compared to both double pass methods up to 180.61 MPa. Moreover, DSP showed better tensile test and hardness test compared to NDP method. The optimum parameters were found to be single pass method with 1200 rpm of rotational speed. Therefore economically sound to only perform SP method to obtain maximum tensile strength for AA6061 FSW with thickness of 6 mm. (paper)

  13. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    - rent work to evaluate the mechanical properties of Zigzag, Armchair and Chiral Single wall Carbon Nanotubes (SWCNT) of different diameters and chiralities. Three dif- ferent types of atomic bonds, that is Carbon–Carbon covalent bond and ...

  14. One piece reactor removal

    International Nuclear Information System (INIS)

    Chia, Wei-Min; Wang, Song-Feng

    1993-01-01

    The strategy of Taiwan Research Reactor Renewal plan is to remove the old reactor block with One Piece Reactor Removal (OPRR) method for installing a new research reactor in original building. In this paper, the engineering design of each transportation works including the work method, the major equipments, the design policy and design criteria is described and discussed. In addition, to ensure the reactor block is safety transported for storage and to guarantee the integrity of reactor base mat is maintained for new reactor, operation safety is drawn special attention, particularly under seismic condition, to warrant safe operation of OPRR. ALARA principle and Below Regulatory Concern (BRC) practice were also incorporated in the planning to minimize the collective dose and the total amount of radioactive wastes. All these activities are introduced in this paper. (J.P.N.)

  15. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    40, Part 4, June 2015, pp. 1301–1311. c Indian Academy of Sciences. Estimation of mechanical properties of single wall carbon nanotubes using molecular mechanics approach. P SUBBA RAO1,2,∗, SUNIL ANANDATHEERTHA3,. G NARAYANA NAIK1 and S GOPALAKRISHNAN1. 1Department of Aerospace Engineering ...

  16. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    Molecular mechanics based finite element analysis is adopted in the current work to evaluate the mechanical properties of Zigzag, Armchair and Chiral Single wall Carbon Nanotubes (SWCNT) of different diameters and chiralities. Three different types of atomic bonds, that is Carbon–Carbon covalent bond and two types of ...

  17. Phonon number measurements using single photon opto-mechanics

    International Nuclear Information System (INIS)

    Basiri-Esfahani, S; Akram, U; Milburn, G J

    2012-01-01

    We describe a system composed of two coupled optical cavity modes with a coupling modulated by a bulk mechanical resonator. In addition, one of the cavity modes is irreversibly coupled to a single photon source. Our scheme is an opto-mechanical realization of the Jaynes–Cummings model where the qubit is a dual rail optical qubit while the bosonic degree of freedom is a matter degree of freedom realized as the bulk mechanical excitation. We show the possibility of engineering phonon number states of the mechanical oscillator in such a system by computing the conditional state of the mechanics after successive photon counting measurements. (paper)

  18. Quasi free mechanism in single photon double ionization of helium

    Energy Technology Data Exchange (ETDEWEB)

    Schoeffler, Markus; Stuck, Christian [Frankfurt Univ., Frankfurt am Main (Germany). Inst. fuer Kernphysik; Lawrence Berkeley National Lab, Berkeley, CA (United States); Jahnke, Till; Waitz, Markus; Trinter, Florian; Lenz, Ute; Schmidt-Boecking, Horst; Doerner, Reinhard [Frankfurt Univ., Frankfurt am Main (Germany). Inst. fuer Kernphysik; Jones, Mathew; Landers, Allen [Auburn University, Auburn, AL (United States); Belkacem, Ali; Weber, Thorsten [Lawrence Berkeley National Lab, Berkeley, CA (United States); Cocke, Lew [Kansas State University, Manhattan, KS (United States)

    2012-07-01

    Double ionization of Helium by a single photon is widely believed to proceed through two mechanisms: knock-off (TS1) or shake-off, with the last one dominating at high photon energies. A new mechanism, termed ''Quasi Free Mechanism'' (QFM) was predicted 35 years ago by Amusia and coworkers, but escaped experimental observation till today. Here we provide the first proof of this mechanism using 800 eV photons from the Advanced Light Source. Fragments (electrons and ions) were measured in coincidence using momentum spectroscopy (COLTRIMS). He{sup (}2+) ions with zero momentum were found - the fingerprint for the QFM.

  19. Single molecule insights on conformational selection and induced fit mechanism

    DEFF Research Database (Denmark)

    Hatzakis, Nikos

    2014-01-01

    of unsynchronized molecules, often masking intrinsic dynamic behavior of proteins and biologically significant transient intermediates. Single molecule measurements are emerging as a powerful tool for characterizing protein function. They offer the direct observation and quantification of the activity, abundance...... and lifetime of multiple states and transient intermediates in the energy landscape, that are typically averaged out in non-synchronized ensemble measurements. Here we survey new insights from single molecule studies that advance our understanding of the molecular mechanisms underlying biomolecular recognition....

  20. Electrical and mechanical effects in single-molecule junctions

    NARCIS (Netherlands)

    Seldenthuis, J.S.

    2011-01-01

    In single-molecule junctions, the behavior of a device is determined by the properties of an individual molecule. In this thesis we develop several models to describe both electrical and mechanical effects in such devices, which can be used to design molecules with a specific functionality. We show

  1. Enhancing the mechanical properties of single-crystal CVD diamond.

    Science.gov (United States)

    Liang, Qi; Yan, Chih-Shiue; Meng, Yufei; Lai, Joseph; Krasnicki, Szczesny; Mao, Ho-Kwang; Hemley, Russell J

    2009-09-09

    Approaches for enhancing the strength and toughness of single-crystal diamond produced by chemical vapor deposition (CVD) at high growth rates are described. CVD processes used to grow single-crystal diamond in high density plasmas were modified to incorporate boron and nitrogen. Semi-quantitative studies of mechanical properties were carried out using Vickers indentation techniques. The introduction of boron in single-crystal CVD diamond can significantly enhance the fracture toughness of this material without sacrificing its high hardness (∼78 GPa). Growth conditions were varied to investigate its effect on boron incorporation and optical properties by means of photoluminescence, infrared, and ultraviolet-visible absorption spectroscopy. Boron can be readily incorporated into single-crystal diamond by the methods used, but with nitrogen addition, the incorporation of boron was hindered. The spectroscopic measurements indicate that nitrogen and boron coexist in the diamond structure, which helps explain the origin of the enhanced fracture toughness of this material. Further, low pressure/high temperature annealing can enhance the intrinsic hardness of single-crystal CVD diamond by a factor of two without appreciable loss in fracture toughness. This doping and post-growth treatment of diamond may lead to new technological applications that require enhanced mechanical properties of diamond.

  2. Single-cell mechanics: the parallel plates technique.

    Science.gov (United States)

    Bufi, Nathalie; Durand-Smet, Pauline; Asnacios, Atef

    2015-01-01

    We describe here the parallel plates technique which enables quantifying single-cell mechanics, either passive (cell deformability) or active (whole-cell traction forces). Based on the bending of glass microplates of calibrated stiffness, it is easy to implement on any microscope, and benefits from protocols and equipment already used in biology labs (coating of glass slides, pipette pullers, micromanipulators, etc.). We first present the principle of the technique, the design and calibration of the microplates, and various surface coatings corresponding to different cell-substrate interactions. Then we detail the specific cell preparation for the assays, and the different mechanical assays that can be carried out. Finally, we discuss the possible technical simplifications and the specificities of each mechanical protocol, as well as the possibility of extending the use of the parallel plates to investigate the mechanics of cell aggregates or tissues. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.

    2013-10-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them. © 2013 Published by Elsevier B.V.

  4. Mechanisms for tertiary creep of single crystal superalloy

    Science.gov (United States)

    Staroselsky, Alexander; Cassenti, Brice

    2008-12-01

    During the thermal-mechanical loading of high temperature single crystal turbine components, all three creep—stages: primary, secondary and tertiary, manifest themselves and, hence, none of them can be neglected. The development of a creep law that includes all three stages is especially important in the case of non-homogeneous thermal loading of the component where significant stress redistribution and relaxation will result. Thus, local creep analysis is crucial for proper design of damage tolerant airfoils. We have developed a crystallographic-based constitutive model and fully coupled it with damage kinetics. The model extends existing approaches for cyclic and thermal-cyclic loading of anisotropic elasto-viscoplastic deformation behavior and damage kinetics of single-crystal materials, allowing prediction of tertiary creep and failure initiation of high temperature components. Our damage model bridges the gap between dislocation dynamics and the continuum mechanics scales and can be used to represent tertiary as well as primary and secondary creep.

  5. Mechanical properties of hydroxyapatite single crystals from nanoindentation data

    Science.gov (United States)

    Zamiri, A.; De, S.

    2011-01-01

    In this paper we compute elasto-plastic properties of hydroxyapatite single crystals from nanindentation data using a two-step algorithm. In the first step the yield stress is obtained using hardness and Young’s modulus data, followed by the computation of the flow parameters. The computational approach is first validated with data from existing literature. It is observed that hydroxyapatite single crystals exhibit anisotropic mechanical response with a lower yield stress along the [1010] crystallographic direction compared to the [0001] direction. Both work hardening rate and work hardening exponent are found to be higher for indentation along the [0001] crystallographic direction. The stress-strain curves extracted here could be used for developing constitutive models for hydroxyapatite single crystals. PMID:21262492

  6. A New Proposal for the Pathogenic Mechanism of Non-Coeliac/Non-Allergic Gluten/Wheat Sensitivity: Piecing Together the Puzzle of Recent Scientific Evidence

    Directory of Open Access Journals (Sweden)

    Valentina Leccioli

    2017-11-01

    Full Text Available Non-coeliac/non-allergic gluten/wheat sensitivity (NCG/WS is a gluten-related disorder, the pathogenesis of which remains unclear. Recently, the involvement of an increased intestinal permeability has been recognized in the onset of this clinical condition. However, mechanisms through which it takes place are still unclear. In this review, we attempt to uncover these mechanisms by providing, for the first time, an integrated vision of recent scientific literature, resulting in a new hypothesis about the pathogenic mechanisms involved in NCG/WS. According to this, the root cause of NCG/WS is a particular dysbiotic profile characterized by decreased butyrate-producing-Firmicutes and/or Bifidobacteria, leading to low levels of intestinal butyrate. Beyond a critical threshold of the latter, a chain reaction of events and vicious circles occurs, involving other protagonists such as microbial lipopolysaccharide (LPS, intestinal alkaline phosphatase (IAP and wheat α-amylase trypsin inhibitors (ATIs. NCG/WS is likely to be a multi-factor-onset disorder, probably transient and preventable, related to quality and balance of the diet, and not to the presence of gluten in itself. If future studies confirm our proposal, this would have important implications both for the definition of the disease, as well as for the prevention and therapeutic-nutritional management of individuals with NCG/WS.

  7. Deformation mechanisms in nanoscale single crystalline electroplated copper pillars

    Science.gov (United States)

    Jennings, Andrew T.

    Scientific research in nanotechnology has enabled advances in a diverse range of applications, such as: electronics, chemical sensing, and cancer treatment. In order to transition these nanotechnology-driven innovations out of the laboratory and into real-world applications, the resilience and mechanical reliability of nanoscale structures must be well understood in order to preserve functionality under real-world operating environments. Understanding the mechanical properties of nanoscale materials is especially important because several authors have shown that single crystalline metal pillars produced through focused-ion-beam milling have unique properties when the pillar diameter, D, approaches nanotechnology-relevant dimensions. The strength, sigma, of these pillars is size-dependent and is well described through a power-law relation showing that smaller is stronger: sigma∝D-n , where n is the exponent and is found to be 0.5≤n≤1.0 in face-centered-cubic metals. In this work, the fundamental deformation mechanisms governing the size-dependent mechanical properties are investigated through uniaxial compression and tension tests of electroplated single crystalline copper pillars with diameters between 75 nm and 1000 nm. At larger pillar diameters, D >125 nm, these copper pillars are shown to obey a similar size-dependent regime, demonstrating that the "smaller is stronger" phenomenon is a function of the pillar microstructure, as opposed to the fabrication route. Furthermore, the dominant dislocation mechanism in this size-dependent regime is shown to be the result of single-arm, or spiral, sources. At smaller pillar diameters, D≤125 nm, a strain-rate-dependent mechanism transition is observed through both the size-strength relation and also quantitative, experimental measures of the activation volume. This new deformation regime is characterized by a size-independent strength and is governed by surface dislocation nucleation, a thermally activated

  8. One-piece modified gasket seal technique.

    Science.gov (United States)

    Wessell, Aaron; Singh, Ameet; Litvack, Zachary

    2013-10-01

    Objectives Review the effectiveness of a modified gasket seal technique utilizing a porous high-density polyethylene plate/rectus sheath fascia construct without fat grafting for primary closure of anterior defects following endoscopic skull base surgery. Design Retrospective review (2011-2012). Setting Single academic medical center. Methods A retrospective review of five patients who underwent expanded endoscopic endonasal surgery for various pathologies (two craniopharyngiomas, two tuberculum meningiomas, and one planum meningioma) was performed. Skull base closure was performed using a one-piece modified gasket seal technique. Primary outcome measures included postoperative cerebrospinal fluid (CSF) leaks and donor site morbidity. Results There were no postoperative CSF leaks. Two patients experienced aseptic meningitis treated with a 14-day course of steroids. Two patients experienced new postoperative chronic/recurrent sinusitis treated with oral antibiotics and topical nasal therapy. There was no donor site morbidity such as infection, hematoma, or hernias. Conclusions The one-piece modified gasket-seal closure is a safe and effective method for reconstruction of endonasal defects of the anterior skull base. Rectus sheath fascia is an appropriate dural substitute for free tissue grafting with low donor site morbidity. The construction of the one-piece graft significantly decreases operative time and lowers the learning curve for multilayered closure.

  9. Mechanical characterization of cellulose single nanofiber by atomic force microscopy

    Science.gov (United States)

    Zhai, Lindong; Kim, Jeong Woong; Lee, Jiyun; Kim, Jaehwan

    2017-04-01

    Cellulose fibers are strong natural fibers and they are renewable, biodegradable and the most abundant biopolymer in the world. So to develop new cellulose fibers based products, the mechanical properties of cellulose nanofibers would be a key. The atomic microscope is used to measure the mechanical properties of cellulose nanofibers based on 3-points bending of cellulose nanofiber. The cellulose nanofibers were generated for an aqueous counter collision system. The cellulose microfibers were nanosized under 200 MPa high pressure. The cellulose nanofiber suspension was diluted with DI water and sprayed on the silicon groove substrate. By performing a nanoscale 3-points bending test using the atomic force microscopy, a known force was applied on the center of the fiber. The elastic modulus of the single nanofiber is obtained by calculating the fiber deflection and several parameters. The elastic modulus values were obtained from different resources of cellulose such as hardwood, softwood and cotton.

  10. Single-molecule mechanics of protein-labelled DNA handles

    Directory of Open Access Journals (Sweden)

    Vivek S. Jadhav

    2016-01-01

    Full Text Available DNA handles are often used as spacers and linkers in single-molecule experiments to isolate and tether RNAs, proteins, enzymes and ribozymes, amongst other biomolecules, between surface-modified beads for nanomechanical investigations. Custom DNA handles with varying lengths and chemical end-modifications are readily and reliably synthesized en masse, enabling force spectroscopic measurements with well-defined and long-lasting mechanical characteristics under physiological conditions over a large range of applied forces. Although these chemically tagged DNA handles are widely used, their further individual modification with protein receptors is less common and would allow for additional flexibility in grabbing biomolecules for mechanical measurements. In-depth information on reliable protocols for the synthesis of these DNA–protein hybrids and on their mechanical characteristics under varying physiological conditions are lacking in literature. Here, optical tweezers are used to investigate different protein-labelled DNA handles in a microfluidic environment under different physiological conditions. Digoxigenin (DIG-dsDNA-biotin handles of varying sizes (1000, 3034 and 4056 bp were conjugated with streptavidin or neutravidin proteins. The DIG-modified ends of these hybrids were bound to surface-modified polystyrene (anti-DIG beads. Using different physiological buffers, optical force measurements showed consistent mechanical characteristics with long dissociation times. These protein-modified DNA hybrids were also interconnected in situ with other tethered biotinylated DNA molecules. Electron-multiplying CCD (EMCCD imaging control experiments revealed that quantum dot–streptavidin conjugates at the end of DNA handles remain freely accessible. The experiments presented here demonstrate that handles produced with our protein–DNA labelling procedure are excellent candidates for grasping single molecules exposing tags suitable for molecular

  11. Mechanical properties and formation mechanisms of a wire of single gold atoms

    DEFF Research Database (Denmark)

    Rubio-Bollinger, G.; Bahn, Sune Rastad; Agrait, N.

    2001-01-01

    A scanning tunneling microscope supplemented with a force sensor is used to study the mechanical properties of a novel metallic nanostructure: a freely suspended chain of single gold atoms. We find that the bond strength of the nanowire is about twice that of a bulk metallic bond. We perform ab i...... stiffness of the nanostructure is strongly affected by the detailed local atomic arrangement at the chain bases.......A scanning tunneling microscope supplemented with a force sensor is used to study the mechanical properties of a novel metallic nanostructure: a freely suspended chain of single gold atoms. We find that the bond strength of the nanowire is about twice that of a bulk metallic bond. We perform ab...... initio calculations of the force at chain fracture and compare quantitatively with experimental measurements. The observed mechanical failure and nanoelastic processes involved during atomic wire fabrication are investigated using molecular dynamics simulations, and we find that the total effective...

  12. Colloid retention mechanisms in single, saturated, variable-aperture fractures.

    Science.gov (United States)

    Rodrigues, S N; Dickson, S E; Qu, J

    2013-01-01

    The characterization of fractured aquifers is commonly limited to the methodologies developed for unconsolidated porous media aquifers, which results in many uncertainties. Recent work indicates that fractured rocks remove more particulates than they are conventionally credited for. This research was designed to quantify the number of Escherichia coli RS2-GFP retained in single, saturated, variable-aperture fractures extracted from the natural environment. Conservative solute and E. coli RS2-GFP tracer experiments were used to elucidate the relationships between dominant retention mechanisms, aperture field characteristics, and flow rate. A non-destructive method of determining a surrogate measure of a coefficient of variation (COV(S)) for each fracture was used to better understand the transport behaviour of E. coli RS2-GFP. The results from this research all point to the importance of aperture field characterization in understanding the fate and transport of contaminants in fractured aquifers. The mean aperture was a very important characteristic in determining particulate recovery, so were matrix properties, COV(s), and flow rate. It was also determined that attachment is a much more significant retention mechanism than straining under the conditions employed in this research. Finally, it was demonstrated that the dominant retention mechanism in a fracture varies depending on the specific discharge. An improved understanding of the mechanisms that influence the fate and transport of contaminants through fractures will lead to the development of better tools and methodologies for the characterization of fractured aquifers, as well as the ability to manipulate the relevant mechanisms to increase or decrease retention, depending on the application. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Synchronization of impacting mechanical systems with a single constraint

    Science.gov (United States)

    Baumann, Michael; Biemond, J. J. Benjamin; Leine, Remco I.; van de Wouw, Nathan

    2018-01-01

    This paper addresses the synchronization problem of mechanical systems subjected to a single geometric unilateral constraint. The impacts of the individual systems, induced by the unilateral constraint, generally do not coincide even if the solutions are arbitrarily 'close' to each other. The mismatch in the impact time instants demands a careful choice of the distance function to allow for an intuitively correct comparison of the discontinuous solutions resulting from the impacts. We propose a distance function induced by the quotient metric, which is based on an equivalence relation using the impact map. The distance function obtained in this way is continuous in time when evaluated along jumping solutions. The property of maximal monotonicity, which is fulfilled by most commonly used impact laws, is used to significantly reduce the complexity of the distance function. Based on the simplified distance function, a Lyapunov function is constructed to investigate the synchronization problem for two identical one-dimensional mechanical systems. Sufficient conditions for the uncoupled individual systems are provided under which local synchronization is guaranteed. Furthermore, we present an interaction law which ensures global synchronization, also in the presence of grazing trajectories and accumulation points (Zeno behavior). The results are illustrated using numerical examples of a 1-DOF mechanical impact oscillator which serves as stepping stone in the direction of more general systems.

  14. Mechanisms of Cellular Proteostasis: Insights from Single-Molecule Approaches

    Science.gov (United States)

    Bustamante, Carlos J.; Kaiser, Christian M.; Maillard, Rodrigo A.; Goldman, Daniel H.; Wilson, Christian A.M.

    2015-01-01

    Cells employ a variety of strategies to maintain proteome homeostasis. Beginning during protein biogenesis, the translation machinery and a number of molecular chaperones promote correct de novo folding of nascent proteins even before synthesis is complete. Another set of molecular chaperones helps to maintain proteins in their functional, native state. Polypeptides that are no longer needed or pose a threat to the cell, such as misfolded proteins and aggregates, are removed in an efficient and timely fashion by ATP-dependent proteases. In this review, we describe how applications of single-molecule manipulation methods, in particular optical tweezers, are shedding new light on the molecular mechanisms of quality control during the life cycles of proteins. PMID:24895851

  15. Waterbomb base: a symmetric single-vertex bistable origami mechanism

    Science.gov (United States)

    Hanna, Brandon H.; Lund, Jason M.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

    2014-09-01

    The origami waterbomb base is a single-vertex bistable origami mechanism that has unique properties which may prove useful in a variety of applications. It also shows promise as a test bed for smart materials and actuation because of its straightforward geometry and multiple phases of motion, ranging from simple to more complex. This study develops a quantitative understanding of the symmetric waterbomb base's kinetic behavior. This is done by completing kinematic and potential energy analyses to understand and predict bistable behavior. A physical prototype is constructed and tested to validate the results of the analyses. Finite element and virtual work analyses based on the prototype are used to explore the locations of the stable equilibrium positions and the force-deflection response. The model results are verified through comparisons to measurements on a physical prototype. The resulting models describe waterbomb base behavior and provide an engineering tool for application development.

  16. Waterbomb base: a symmetric single-vertex bistable origami mechanism

    International Nuclear Information System (INIS)

    Hanna, Brandon H; Lund, Jason M; Magleby, Spencer P; Howell, Larry L; Lang, Robert J

    2014-01-01

    The origami waterbomb base is a single-vertex bistable origami mechanism that has unique properties which may prove useful in a variety of applications. It also shows promise as a test bed for smart materials and actuation because of its straightforward geometry and multiple phases of motion, ranging from simple to more complex. This study develops a quantitative understanding of the symmetric waterbomb base's kinetic behavior. This is done by completing kinematic and potential energy analyses to understand and predict bistable behavior. A physical prototype is constructed and tested to validate the results of the analyses. Finite element and virtual work analyses based on the prototype are used to explore the locations of the stable equilibrium positions and the force–deflection response. The model results are verified through comparisons to measurements on a physical prototype. The resulting models describe waterbomb base behavior and provide an engineering tool for application development. (paper)

  17. Retaining Device For One-Piece Battery

    Science.gov (United States)

    Gilabert, Claude; Leturque, Michel; Verhoog, Roclof

    2000-08-01

    The present invention consists of a device for retaining a one-piece battery with a prismatic casing having two longitudinal walls and two transverse walls. The device contains two plates applied to respective transverse walls and at least one cinching mechanism for the plates consisting of at least one flat strip closed on itself surrounding the longitudinal walls and the transverse walls are provided with the plates. The device is characterized in that at least one of the plates contains at least one recessed housing and the strip closely follows the shape of the housing.

  18. Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Trung Dung; Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia)

    2014-05-05

    Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

  19. Opto-acoustic microscopy reveals adhesion mechanics of single cells

    Science.gov (United States)

    Abi Ghanem, Maroun; Dehoux, Thomas; Liu, Liwang; Le Saux, Guillaume; Plawinski, Laurent; Durrieu, Marie-Christine; Audoin, Bertrand

    2018-01-01

    Laser-generated GHz-ultrasonic-based technologies have shown the ability to image single cell adhesion and stiffness simultaneously. Using this new modality, we here demonstrate quantitative indicators to investigate contact mechanics and adhesion processes of the cell. We cultured human cells on a rigid substrate, and we used an inverted pulsed opto-acoustic microscope to generate acoustic pulses containing frequencies up to 100 GHz in the substrate. We map the reflection of the acoustic pulses at the cell-substrate interface to obtain images of the acoustic impedance of the cell, Zc, as well as of the stiffness of the interface, K, with 1 μm lateral resolution. Our results show that the standard deviation ΔZc reveals differences between different cell types arising from the multiplicity of local conformations within the nucleus. From the distribution of K-values within the nuclear region, we extract a mean interfacial stiffness, Km, that quantifies the average contact force in areas of the cell displaying weak bonding. By analogy with classical contact mechanics, we also define the ratio of the real to nominal contact areas, Sr/St. We show that Km can be interpreted as a quantitative indicator of passive contact at metal-cell interfaces, while Sr/St is sensitive to active adhesive processes in the nuclear region. The ability to separate the contributions of passive and active adhesion processes should allow gaining insight into cell-substrate interactions, with important applications in tissue engineering.

  20. [Suggestions to strengthen quality management of herbal decoction pieces--based on production chain of herbal decoction pieces].

    Science.gov (United States)

    Liu, Yan; Nie, Qing; Chen, Jing

    2015-08-01

    With the development of society and the improvement of people's living standards, the effect of Chinese medicine in treatment and health care is more and more prominent. The herbal decoction pieces are the important part of Chinese medicine,it can be applied directly to clinical treatment and it's also the raw material of Chinese patent medicine. Therefore, the quality of herbal decoction pieces is quite important. The parts of the production of herbal decoction pieces are numerous, and there are possibilities of adverse effects on the quality of the herbal decoction pieces in every part. In this paper, we based on the production chain of herbal decoction pieces, analyzed the main problem that affect the quality of herbal decoction pieces in the part of selection of Chinese herbal medicines, planting, purchasing, processing, packaging, storage and transport, such as the poor quality of seed and seedlings of plant-based Chinese medicines, some plants left their place of origin and have been introduced in the place that is not suitable for this kind of plant, the insufficient growth time and the excessive harmful substances. The purchasers and the accepters lack of professional knowledge and professional ethics. The mechanism of processing is not clear, the standards can not be uniformed, and lack of qualified person in processing, etc. So we suggest: intensify the basic research of key scientific issues. Improve the quality of persons who work in herbal decoction pieces; Establish an "integration" mode of operation in herbal decoction pieces enterprise; Breeding high quality plant resources, establish the large-scale planting basement; Make the packing of herbal decoction pieces standard; Establish the modernization traditional Chinese medicine logistics enterprise.

  1. Comparison of immediately loaded flapless-placed one-piece implants and flapped-placed conventionally loaded two-piece implants, both fitted with all-ceramic single crowns, 
in the posterior mandible: 3-year results from 
a randomised controlled pilot trial.

    Science.gov (United States)

    Bömicke, Wolfgang; Gabbert, Olaf; Koob, Andreas; Krisam, Johannes; Rammelsberg, Peter

    To compare outcomes for immediately loaded one-piece implants (OPI), placed flapless, and conventionally loaded two-piece implants (TPI), placed after two-stage flapped surgery. Thirty-eight participants were randomised to receive either one OPI (19 participants, OPI group) or one TPI (19 participants, TPI group) inserted in the posterior mandible with a torque of at least 35 Ncm according to a parallel group design. OPI were immediately loaded with non-occluding temporary crowns. After 3 months, TPI were exposed and implants in both groups were occlusally loaded with zirconia crowns. Outcome measures were implant failure, prosthesis failure, any complication and changes of probing pocket depth (PPD), plaque index (PI), gingiva index (GI), and peri-implant marginal bone level, recorded by unblinded assessors. Three years after occlusal loading, three participants dropped out from the TPI group. There were no statistically significant differences between the groups with regard to participants with implant failure (OPI group 1/19; TPI group 0/16; difference in proportions (DIP), -5.3%; 95% confidence interval (CI) -15.3 to 4.8; P = 1.000), prosthesis failure (OPI group 3/19, TPI group 5/16; DIP, 15.5%; 95% CI -12.6 to 43.5; P = 0.424), any complication (OPI group 6/19, TPI group 5/16; DIP, -0.3%; 95% CI -31.2 to 30.5; P = 1.000), or changes of PPD (P =0.174), PI (P = 0.222), or GI (P = 0.415). Veneer chipping accounted for most prosthesis failures and complications. On average OPI and TPI lost 1.34 mm and 0.67 mm of marginal bone, respectively, the difference between groups being statistically significant (mean difference, 0.66 mm; 95% CI -0.02 to 1.34; P = 0.024) in favour of TPI implants. Both implant procedures might be viable in the short term, but statistically significantly more bone loss might be indicative of future problems with OPI. Because of the high incidence of chipping, veneered zirconia crowns cannot be recommended

  2. Mechanical Properties of a Single Electrospun Fiber and its Structures

    NARCIS (Netherlands)

    Gu, S.; Gu, Shuying; Wu, Qi-Lin; Ren, Jie; Vancso, Gyula J.

    2005-01-01

    A method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. The Young's modulus can be calculated from the force-displacement curves obtained by the bending of a single fiber attached to an atomic force microscopy (AFM) cantilever. It is suggested that

  3. One Piece Immediately Loaded Implants Versus 1 Piece or 2 Pieces Delayed: 3 Years Outcome.

    Science.gov (United States)

    Duda, Mariusz; Matalon, Shlomo; Lewinstein, Israel; Harel, Noga; Block, Jonathan; Ormianer, Zeev

    2016-02-01

    To compare time-dependent outcome of immediately loaded 1-piece (1P) implants with delayed loaded 1P and 2-piece (2P) implants. A cohort of 33 patients divided into 3 groups: group A, 13 patients, 49 immediately placed and loaded 1P implants; group B, 11 patients, immediately placed and delayed loaded 1P implants; and group C, 10 patients, 39 2P implants delayed placed and loaded in a two-stage procedure. Marginal bone loss (MBL) was analyzed using x-ray radiography every 6 months, 1 year, and 3 years. A statistically significant mean MBL was observed between baseline, 6 months, 1 year, and 3 years in all groups. There was no statistical significant difference in MBL between immediate and delayed loaded 1P implants. MBL around mandibular implants was lower compared with maxillary implants. 2P implants showed less MBL compared with 1P implants in both maxilla and mandible. There was no statistical difference in MBL between immediate and delayed loaded 1P implants. Immediate loaded implants show more MBL in maxilla.

  4. Piezoresistivity of mechanically drawn single-walled carbon nanotube (SWCNT) thin films-: mechanism and optimizing principle

    Science.gov (United States)

    Obitayo, Waris

    The individual carbon nanotube (CNT) based strain sensors have been found to have excellent piezoresistive properties with a reported gauge factor (GF) of up to 3000. This GF on the other hand, has been shown to be structurally dependent on the nanotubes. In contrast, to individual CNT based strain sensors, the ensemble CNT based strain sensors have very low GFs e.g. for a single walled carbon nanotube (SWCNT) thin film strain sensor, GF is ~1. As a result, studies which are mostly numerical/analytical have revealed the dependence of piezoresistivity on key parameters like concentration, orientation, length and diameter, aspect ratio, energy barrier height and Poisson ratio of polymer matrix. The fundamental understanding of the piezoresistive mechanism in an ensemble CNT based strain sensor still remains unclear, largely due to discrepancies in the outcomes of these numerical studies. Besides, there have been little or no experimental confirmation of these studies. The goal of my PhD is to study the mechanism and the optimizing principle of a SWCNT thin film strain sensor and provide experimental validation of the numerical/analytical investigations. The dependence of the piezoresistivity on key parameters like orientation, network density, bundle diameter (effective tunneling area), and length is studied, and how one can effectively optimize the piezoresistive behavior of a SWCNT thin film strain sensors. To reach this goal, my first research accomplishment involves the study of orientation of SWCNTs and its effect on the piezoresistivity of mechanically drawn SWCNT thin film based piezoresistive sensors. Using polarized Raman spectroscopy analysis and coupled electrical-mechanical test, a quantitative relationship between the strain sensitivity and SWCNT alignment order parameter was established. As compared to randomly oriented SWCNT thin films, the one with draw ratio of 3.2 exhibited ~6x increase on the GF. My second accomplishment involves studying the

  5. Physical mechanisms of single-event effects in advanced microelectronics

    International Nuclear Information System (INIS)

    Schrimpf, Ronald D.; Weller, Robert A.; Mendenhall, Marcus H.; Reed, Robert A.; Massengill, Lloyd W.

    2007-01-01

    The single-event error rate in advanced semiconductor technologies can be estimated more accurately than conventional methods by using simulation based on accurate descriptions of a large number of individual particle interactions. The results can be used to select the ion types and energies for accelerator testing and to identify situations in which nuclear reactions will contribute to the error rate

  6. Coupling of single quantum emitters to plasmons propagating on mechanically etched wires

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Lu, Ying-Wei

    2013-01-01

    We demonstrate the coupling of a single nitrogen vacancy center in a nanodiamond to propagating plasmonic modes of mechanically etched silver nanowires. The mechanical etch is performed on single crystalline silver nanoplates by the tip of an atomic force microscope cantilever to produce wires...

  7. Multiple glass pieces in paranasal sinuses

    Directory of Open Access Journals (Sweden)

    Syed Ahmed Mohiuddin

    2011-01-01

    Full Text Available Here, a case has been reported of a road traffic accident with multiple glass pieces arranged in an unusual pattern in the left maxillary sinus, ethmoid sinus, nasopharynx and medial side of the orbit, as seen in the radiographs. Combined surgical approach through the existing wound and endoscopic surgery was successfully used to remove nearly all the glass pieces.

  8. Biomechanical evaluation of one-piece and two-piece small-diameter dental implants: In-vitro experimental and three-dimensional finite element analyses.

    Science.gov (United States)

    Wu, Aaron Yu-Jen; Hsu, Jui-Ting; Chee, Winston; Lin, Yun-Te; Fuh, Lih-Jyh; Huang, Heng-Li

    2016-09-01

    Small-diameter dental implants are associated with a higher risk of implant failure. This study used both three-dimensional finite-element (FE) simulations and in-vitro experimental tests to analyze the stresses and strains in both the implant and the surrounding bone when using one-piece (NobelDirect) and two-piece (NobelReplace) small-diameter implants, with the aim of understanding the underlying biomechanical mechanisms. Six experimental artificial jawbone models and two FE models were prepared for one-piece and two-piece 3.5-mm diameter implants. Rosette strain gauges were used for in-vitro tests, with peak values of the principal bone strain recorded with a data acquisition system. Implant stability as quantified by Periotest values (PTV) were also recorded for both types of implants. Experimental data were analyzed statistically using Wilcoxon's rank-sum test. In FE simulations, the peak value and distribution of von-Mises stresses in the implant and bone were selected for evaluation. In in-vitro tests, the peak bone strain was 42% lower for two-piece implants than for one-piece implants. The PTV was slightly lower for one-piece implants (PTV = -6) than for two-piece implants (PTV = -5). In FE simulations, the stresses in the bone and implant were about 23% higher and 12% lower, respectively, for one-piece implants than those for two-piece implants. Due to the higher peri-implant bone stresses and strains, one-piece implants (NobelDirect) might be not suitable for use as small-diameter implants. Copyright © 2016. Published by Elsevier B.V.

  9. Failure mechanisms in single-point incremental forming of metals

    DEFF Research Database (Denmark)

    Silva, Maria B.; Nielsen, Peter Søe; Bay, Niels

    2011-01-01

    The last years saw the development of two different views on how failure develops in single-point incremental forming (SPIF). Today, researchers are split between those claiming that fracture is always preceded by necking and those considering that fracture occurs with suppression of necking. Eac...... and involves independent determination of formability limits by necking and fracture using tensile and hydraulic bulge tests in conjunction with SPIF of benchmark shapes under laboratory conditions.......The last years saw the development of two different views on how failure develops in single-point incremental forming (SPIF). Today, researchers are split between those claiming that fracture is always preceded by necking and those considering that fracture occurs with suppression of necking. Each...... on formability limits and development of fracture. The unified view conciliates the aforementioned different explanations on the role of necking in fracture and is consistent with the experimental observations that have been reported in the past years. The work is performed on aluminium AA1050-H111 sheets...

  10. Mechanisms of photoconduction degradation in cadmium-sulfide single crystals

    International Nuclear Information System (INIS)

    Burlak, A.V.; Ignatov, A.V.; Serdyuk, V.V.; Furlej, A.I.

    1987-01-01

    Calculation of the kinetics of degradation in photosensitive semiconductors of A 2 B 6 group is presented. It enables to consider the mechanism of photoconduction degradation ( PD ) on the basis of experimental dependences of photoconduction on time, mesured at diffeent temperatures and intensities of exciting light. Experimental investigations of PD were conducted with copper alloyed CdS volumetric crystals. It was concluded that PD in studied samples was conditioned by small donor ( Cdi ) depature to sinks

  11. Crystallization and mechanical properties of functionalized single-walled carbon nanotubes/polyvinylidene fluoride composites

    DEFF Research Database (Denmark)

    Ma, Jing; Iftekharul Haque, Rubaiyet; Larsen, Mikael

    2012-01-01

    Single-walled carbon nanotubes were purified and functionalized by nitric acid and octadecylamine. Raman and Fourier transform infrared spectroscopy were used to characterize the functionalization of the single-walled carbon nanotubes. Polyvinylidene flouride nanocomposites containing 1 wt......% purified or functionalized single-walled carbon nanotubes were prepared by solution blending and injection molding. The dispersion of different carbon nanotubes in dimethylformamide and in polyvinylidene flouride has been investigated. Mechanical properties show that adding single-walled carbon nanotubes...

  12. Operation analysis of a Chebyshev-Pantograph leg mechanism for a single DOF biped robot

    Science.gov (United States)

    Liang, Conghui; Ceccarelli, Marco; Takeda, Yukio

    2012-12-01

    In this paper, operation analysis of a Chebyshev-Pantograph leg mechanism is presented for a single degree of freedom (DOF) biped robot. The proposed leg mechanism is composed of a Chebyshev four-bar linkage and a pantograph mechanism. In contrast to general fully actuated anthropomorphic leg mechanisms, the proposed leg mechanism has peculiar features like compactness, low-cost, and easy-operation. Kinematic equations of the proposed leg mechanism are formulated for a computer oriented simulation. Simulation results show the operation performance of the proposed leg mechanism with suitable characteristics. A parametric study has been carried out to evaluate the operation performance as function of design parameters. A prototype of a single DOF biped robot equipped with two proposed leg mechanisms has been built at LARM (Laboratory of Robotics and Mechatronics). Experimental test shows practical feasible walking ability of the prototype, as well as drawbacks are discussed for the mechanical design.

  13. Model Checking in Bits and Pieces

    Directory of Open Access Journals (Sweden)

    Kedar S. Namjoshi

    2013-09-01

    Full Text Available Fully automated verification of concurrent programs is a difficult problem, primarily because of state explosion: the exponential growth of a program state space with the number of its concurrently active components. It is natural to apply a divide and conquer strategy to ameliorate state explosion, by analyzing only a single component at a time. We show that this strategy leads to the notion of a "split" invariant, an assertion which is globally inductive, while being structured as the conjunction of a number of local, per-component invariants. This formulation is closely connected to the classical Owicki-Gries method and to Rely-Guarantee reasoning. We show how the division of an invariant into a number of pieces with limited scope makes it possible to apply new, localized forms of symmetry and abstraction to drastically simplify its computation. Split invariance also has interesting connections to parametric verification. A quantified invariant for a parametric system is a split invariant for every instance. We show how it is possible, in some cases, to invert this connection, and to automatically generalize from a split invariant for a small instance of a system to a quantified invariant which holds for the entire family of instances.

  14. Conduction Mechanisms and Structure of Ionomeric Single-Ion Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Ralph H. [Pennsylvania State Univ., University Park, PA (United States); Maranas, Janna K. [Pennsylvania State Univ., University Park, PA (United States); Mueller, Karl T. [Pennsylvania State Univ., University Park, PA (United States); Runt, James [Pennsylvania State Univ., University Park, PA (United States); Winey, Karen I. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2015-03-01

    Our team has designed using DFT (Gaussian) and synthesized low glass transition temperature single-ion conductors that are either polyanions that conduct small cations Li+, Na+, Cs+ or polycations that conduct small anions F-, OH-, Br-. We utilize a wide range of complimentary experimental materials characterization tools to understand ion transport; differential scanning calorimetry, dielectric relaxation spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, linear viscoelasticity, X-ray scattering and molecular dynamics simulations. The glass transition temperature Tg needs to be as low as possible to facilitate ion transport, so the nonionic parts of the polymer need to be polar, flexible and have strong solvation interactions with the ions. The lowest Tg we have managed for polyanions conducting Li+ is -60 °C. In contrast, polysiloxanes with PEO side chains and tetrabutylphosphonium cationic side groups have Tg ≈ -75 °C that barely increases with ion content, as anticipated by DFT. A survey of all polyanions in the literature suggests that Tg < -80 °C is needed to achieve the 10-4 S/cm conductivity needed for battery separators.

  15. Understanding the kinetic mechanism of RNA single base pair formation.

    Science.gov (United States)

    Xu, Xiaojun; Yu, Tao; Chen, Shi-Jie

    2016-01-05

    RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.

  16. One-piece versus two-piece orbitozygomatic craniotomy: quantitative and qualitative considerations.

    Science.gov (United States)

    Tanriover, Necmettin; Ulm, Arthur J; Rhoton, Albert L; Kawashima, Masatou; Yoshioka, Nobutaka; Lewis, Stephen B

    2006-04-01

    The orbitozygomatic (OZ) craniotomy minimizes brain retraction and improves cranial base exposure by providing a multidirectional view, increased operative angles and working space. The two main variations of the approach include the one-piece and the two-piece types. The microsurgical anatomy of the one- and two-piece OZ craniotomies are presented with the goal of comparing the extent of orbital roof removal between these two craniotomies and the effect of orbital roof removal on operative exposure. Ten two-piece and 11 one-piece OZ craniotomies were performed in a stepwise manner simulating the approaches on formalin fixed specimens. The orbital surface area removed above the frontozygomatic suture extending medially over the orbital roof was measured from each bone flap. The two-sided unpaired t test using STATA 7.0 software was used to compare the amount of orbital roof removed using the two approaches. The two-piece OZ craniotomy allowed for the removal of a larger portion of the roof and lateral wall of the orbit than the one-piece. The total orbitotomy, including the orbital roof plus the part of the lateral wall above the frontozygomatic suture, had an average surface area of 996 +/- 229 mm for the two piece and 372 +/- 103 mm for the one-piece. The orbital roof made up 27 +/- 18% of the orbital osteotomy for the one-piece craniotomies and 67 +/- 10% of the osteotomy for the two-piece craniotomies (P piece OZ craniotomy allows for more extensive orbital roof removal and better visualization of the basal frontal lobe. Therefore, the two-piece may result in a lower incidence of enophtalmus and poor cosmetic outcomes, particularly if the remaining orbital roof must be removed piecemeal during the one-piece OZ craniotomy in order to obtain satisfactory exposure.

  17. Last piece of ATLAS takes the plunge

    CERN Document Server

    2008-01-01

    On Friday 29 February the second small wheel was lowered 100 metres underground into the ATLAS cavern in front of a captivated audience. Although called the "small wheels" they are small in name only - each wheel is 9.3 metres in diameter and weighs 100 tonnes including the massive shielding elements. This piece completes ATLAS’ muon spectrometer, which has the ability to accurately track particles to the width of a human hair. The first piece of ATLAS was installed in 2003 and, five years later, this small wheel is the final large piece of the detector to take the subterranean voyage to its final resting place.

  18. Mechanisms of gravitropism in single-celled systems

    Science.gov (United States)

    Greuel, Nicole; Braun, Markus; Hauslage, Jens; Wiemann, Katharina

    pressure exerted by sedimented statoliths. Instead, the experiments provide evidence that graviperception depends on direct interactions between statoliths and a yet unknown gravireceptor.Graviperception in higher plant statocytes was also found to be not dependent on mechanical pressure but on direct interactions between gravireceptors and statoliths. In contrast to Chara rhizoids, however, the actin system of higher plant statocytes is not essentially required for gravity-sensing. Parabolic flight experiments and ground controls indicated that disruption of the actin cytoskeleton in root statocytes by using Latrunculin B results in an increased gravisensitivity and in a promoted gravitropic curvature rather than in an inhibition. It is speculated that the actomyosin system in statocytes has a fine-tuning function in the early phases of gravity sensing. Actin in higher plant statocytes may be required to optimize statolith-receptor interactions and to keep the sensing system highly sensitive on one hand, but on the other hand actomyosin-statolith interactions seem to avoid unfavourable responses to only transient stimuli.Investigating the unicellular characean rhizoid has greatly enhanced our understanding of gravity sensing processes in plants and there is increasing evidence that higher plants and characean rhizoids share common processes in the signalling pathway of gravity-oriented growth.

  19. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

    DEFF Research Database (Denmark)

    Andersen, Anders Peter; Madsen, Jacob; Reichelt, Christian Günther

    2015-01-01

    even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes......¨dinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can...... not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics....

  20. 29 CFR 1910.177 - Servicing multi-piece and single piece rim wheels.

    Science.gov (United States)

    2010-07-01

    ..., trailers, buses and off-road machines. It does not apply to the servicing of rim wheels used on automobiles... components shall not be interchanged except as provided in the charts or in the applicable rim manual. (2...

  1. Anterior segment parameters: comparison of 1-piece and 3-piece acrylic foldable intraocular lenses.

    Science.gov (United States)

    Behrouz, Mahmoud Jabbarvand; Kheirkhah, Ahmad; Hashemian, Hesam; Nazari, Rahman

    2010-10-01

    To compare anterior segment parameters between 1-piece and 3-piece acrylic foldable intraocular lenses (IOLs). Farabi Eye Hospital, Tehran, Iran. Prospective randomized comparative case series. Eyes scheduled for phacoemulsification were randomized into 2 equal groups to receive a 1-piece (AcrySof SA60AT) or 3-piece (AcrySof MA60AC) foldable acrylic IOL. Scheimpflug imaging (Pentacam) was used to measure anterior segment parameters, including anterior chamber depth (ACD), anterior chamber angle (ACA), and anterior chamber volume (ACV), preoperatively and 1 week and 3 months postoperatively. The study evaluated 125 eyes (123 patients). There was a statistically significant postoperative increase in ACD, ACA, and ACV at 1 week and 3 months in both IOL groups. Although the mean ACD was significantly higher in the 3-piece group at 1 week, there was no significant between-group difference in ACD, ACA, or ACV at 3 months. There was no significant change in anterior segment parameters from 1 week to 3 months in the 1-piece group; however, the 3-piece group had statistically significant decreases in ACD, ACA, and ACV. Refraction remained stable throughout the follow-up in the 1-piece group but showed a significant myopic shift from 1 week to 3 months in the 3-piece group. After phacoemulsification, the 1-piece acrylic foldable IOL showed little axial movement and provided stable refraction throughout the follow-up. The 3-piece IOL had significant forward movement and led to a myopic shift within 3 months postoperatively. Results indicate that spectacles can be prescribed earlier in eyes with a 1-piece IOL. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  2. Bio imaging of intracellular NO production in single bone cells after mechanical stimulation

    NARCIS (Netherlands)

    Vatsa, A.; Mizuno, D.; Smit, T.H.; Schmidt, C.; Mac Kintosh, F.C.; Klein-Nulend, J.

    2006-01-01

    We show the intracellular upregulation of NO production after mechanical stimulation, an essential chemical signal in bone remodeling. This is done in real time using the fluorescent chromophore DAR-4M AM. Differences in cellular response to mechanical stimulation of different regions of a single

  3. Analysis of the impacts of mechanical errors on the RF performance of a single spoke cavity

    International Nuclear Information System (INIS)

    Yao Zhongyuan; Lu Xiangyang; Zhang Baocheng; Quan Shengwen; He Feisi; Zhao Kui

    2010-01-01

    Mechanical errors can not be avoided in fabrication. They will cause geometry errors and have impacts on the cavity performance. This paper systematically analyzes the impacts of mechanical errors on the RF performance of Peking University single spoke cavity. The various kinds of shape and size errors are considered, the influences on the resonation frequency and field flatness are studied by numerical simulation and the theoretical models are analyzed. The results show that the single spoke cavity is robust with respect to the mechanical tolerance. It also indicates the most essential factors for fabrication. (authors)

  4. Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring

    Directory of Open Access Journals (Sweden)

    Yuya Kitaguchi

    2015-10-01

    Full Text Available Mechanical methods for single-molecule control have potential for wide application in nanodevices and machines. Here we demonstrate the operation of a single-molecule switch made functional by the motion of a phenyl ring, analogous to the lever in a conventional toggle switch. The switch can be actuated by dual triggers, either by a voltage pulse or by displacement of the electrode, and electronic manipulation of the ring by chemical substitution enables rational control of the on-state conductance. Owing to its simple mechanics, structural robustness, and chemical accessibility, we propose that phenyl rings are promising components in mechanical molecular devices.

  5. SSO - Single-Sign-On Profile: Authentication Mechanisms Version 2.0

    Science.gov (United States)

    Taffoni, Giuliano; Schaaf, André; Rixon, Guy; Major, Brian; Taffoni, Giuliano

    2017-05-01

    Approved client-server authentication mechanisms are described for the IVOA single-sign-on profile: No Authentication; HTTP Basic Authentication; TLS with passwords; TLS with client certificates; Cookies; Open Authentication; Security Assertion Markup Language; OpenID. Normative rules are given for the implementation of these mechanisms, mainly by reference to pre-existing standards. The Authorization mechanisms are out of the scope of this document.

  6. Investigating and improving student understanding of quantum mechanics in the context of single photon interference

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2017-06-01

    Single photon experiments involving a Mach-Zehnder interferometer can illustrate the fundamental principles of quantum mechanics, e.g., the wave-particle duality of a single photon, single photon interference, and the probabilistic nature of quantum measurement involving single photons. These experiments explicitly make the connection between the abstract quantum theory and concrete laboratory settings and have the potential to help students develop a solid grasp of the foundational issues in quantum mechanics. Here we describe students' conceptual difficulties with these topics in the context of Mach-Zehnder interferometer experiments with single photons and how the difficulties found in written surveys and individual interviews were used as a guide in the development of a Quantum Interactive Learning Tutorial (QuILT). The QuILT uses an inquiry-based approach to learning and takes into account the conceptual difficulties found via research to help upper-level undergraduate and graduate students learn about foundational quantum mechanics concepts using the concrete quantum optics context. It strives to help students learn the basics of quantum mechanics in the context of single photon experiment, develop the ability to apply fundamental quantum principles to experimental situations in quantum optics, and explore the differences between classical and quantum ideas in a concrete context. We discuss the findings from in-class evaluations suggesting that the QuILT was effective in helping students learn these abstract concepts.

  7. Ambicor Two-Piece Inflatable Penile Prosthesis: Background and Contemporary Outcomes.

    Science.gov (United States)

    Ko, Oliver S; Bennett, Nelson E

    2018-04-01

    The two-piece inflatable penile prosthesis (IPP; Ambicor) might be a preferred option for men with erectile dysfunction (ED) who have significant retroperitoneal scarring, limited manual dexterity, or other issues. There are reported differences in outcomes and patient and partner satisfaction between three-piece and two-piece IPPs. To report contemporary outcomes, patient and partner satisfaction, and mechanical durability data of the two-piece compared with the three-piece IPP. A PubMed search was performed related to two-piece penile prostheses. Emphasis was placed on perioperative outcomes and patient and/or partner satisfaction scores. Non-English-language articles were excluded. Use of the Ambicor two-piece penile prosthesis was assessed by outlining the contemporary literature. The etiology of ED in this population, mechanical attributes, penile morphologic changes, satisfaction, and its use in special populations were reviewed. The most common etiology of ED for placement of the device remains a vasculogenic cause (range = 11-62%). Overall complication rates were 2.1% to 11.2% for the general population. Mechanical failure was seen in 0.7% to 6.1%. Infection rates were 0.7% to 4.8%. Spontaneous deflation was seen in approximately 25%. Higher complication rates were found in transgender patients after neophallus creation and the two-piece IPP could offer better durability compared with the three-piece IPP. Longer operative times, greater use of advanced dilation techniques, and greater length loss also have been reported. Overall satisfaction rates are higher than 85%. The predominant etiology of ED for two-piece penile prosthesis placement is vasculogenic. There is a trend toward IPP insertion in patients after radical prostatectomy or who have spinal cord injury. The two-piece device has similar complication rates and high patient satisfaction scores compared with three-piece IPPs. Further larger prospective studies are needed to validate our findings

  8. Comparison of decentration and tilt between one piece and three piece polymethyl methacrylate intraocular lenses

    Science.gov (United States)

    Hayashi, K.; Hayashi, H.; Nakao, F.; Hayashi, F.

    1998-01-01

    BACKGROUND—The extent of the decentration and tilt was prospectively compared between one piece polymethyl methacrylate (PMMA) and three piece PMMA intraocular lenses (IOLs) which were implanted in the capsular bag after performing continuous curvilinear capsulorhexis.
METHODS—91 patients underwent a one piece PMMA IOL implantation in one eye as well as the implantation of the three piece PMMA IOL with polyvinylidene fluoride loops in the opposite eye. The length of the lens decentration and the angle of the tilt were quantitated using the anterior eye segment analysis system (EAS-1000) at 1 week as well as 1, 3, and 6 months postoperatively.
RESULTS—The mean length of the decentration in the one piece IOL was smaller than that in the three piece IOL at 1 week (p=0.0092), 1 month (p=0.0044), 3 months (p=0.0069), and 6 months (p=0.0010) postoperatively. However, no significant difference was found in the degree of the tilt between the two types of IOLs throughout the observation periods.
CONCLUSION—These results clarified that the one piece PMMA IOL with rigid PMMA haptics implanted in the capsular bag provides a better centration than the three piece PMMA IOL with flexible haptics, whereas the tilt was the same between the two types of IOLs.

 Keywords: intraocular lens; decentration; tilt; continuous curvilinear capsulorhexis PMID:9640193

  9. Last piece of the puzzle for ATLAS

    CERN Multimedia

    Clare Ryan

    At around 15.40 on Friday 29th February the ATLAS collaboration cracked open the champagne as the second of the small wheels was lowered into the cavern. Each of ATLAS' small wheels are 9.3 metres in diameter and weigh 100 tonnes including the massive shielding elements. They are the final parts of ATLAS' muon spectrometer. The first piece of ATLAS was installed in 2003 and since then many detector elements have journeyed down the 100 metre shaft into the ATLAS underground cavern. This last piece completes this gigantic puzzle.

  10. Imaging Action Potential in Single Mammalian Neurons by Tracking the Accompanying Sub-Nanometer Mechanical Motion.

    Science.gov (United States)

    Yang, Yunze; Liu, Xian-Wei; Wang, Hui; Yu, Hui; Guan, Yan; Wang, Shaopeng; Tao, Nongjian

    2018-03-28

    Action potentials in neurons have been studied traditionally by intracellular electrophysiological recordings and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with a sub-nanometer detection limit. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons by averaging the repeated action potential spikes. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2-0.4 nm. The work indicates that action potentials may be studied noninvasively in single mammalian neurons by label-free imaging of the accompanying sub-nanometer mechanical motion.

  11. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes.

    Science.gov (United States)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-21

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.

  12. Estimation of turgor pressure through comparison between single plant cell and pressurized shell mechanics

    Science.gov (United States)

    Durand-Smet, P.; Gauquelin, E.; Chastrette, N.; Boudaoud, A.; Asnacios, A.

    2017-10-01

    While plant growth is well known to rely on turgor pressure, it is challenging to quantify the contribution of turgor pressure to plant cell rheology. Here we used a custom-made micro-rheometer to quantify the viscoelastic behavior of isolated plant cells while varying their internal turgor pressure. To get insight into how plant cells adapt their internal pressure to the osmolarity of their medium, we compared the mechanical behavior of single plant cells to that of a simple, passive, pressurized shell: a soccer ball. While both systems exhibited the same qualitative behavior, a simple mechanical model allowed us to quantify turgor pressure regulation at the single cell scale.

  13. Sealed One Piece Battery Having A Prism Shape Container

    Science.gov (United States)

    Verhoog, Roelof; Barbotin, Jean-Loup

    2000-03-28

    A sealed one-piece battery having a prism-shaped container including: a tank consisting of a single plastic material, a member fixed and sealed to the tank and to partitions on the side of the tank opposite the transverse wall to seal the tank, two flanges fixed and sealed to longitudinal walls defining flow compartments for a heat-conducting fluid, and two tubes on the transverse wall of the tank forming an inlet and an outlet for fluid common to the compartments.

  14. Mass sensors with mechanical traps for weighing single cells in different fluids.

    Science.gov (United States)

    Weng, Yaochung; Delgado, Francisco Feijó; Son, Sungmin; Burg, Thomas P; Wasserman, Steven C; Manalis, Scott R

    2011-12-21

    We present two methods by which single cells can be mechanically trapped and continuously monitored within the suspended microchannel resonator (SMR) mass sensor. Since the fluid surrounding the trapped cell can be quickly and completely replaced on demand, our methods are well suited for measuring changes in cell size and growth in response to drugs or other chemical stimuli. We validate our methods by measuring the density of single polystyrene beads and Saccharomyces cerevisiae yeast cells with a precision of approximately 10(-3) g cm(-3), and by monitoring the growth of single mouse lymphoblast cells before and after drug treatment.

  15. Performance evaluation of aluminium test piece against ...

    African Journals Online (AJOL)

    Image processing with Catphan 700 uses the automated Quality Assurance software restricted to only Digital Imaging and Communications in Medicine images. For this reason, an aluminium (Al) test piece device was fabricated for image processing in different image format for spatial resolution measurement.

  16. One-Piece Force-Transducer Body

    Science.gov (United States)

    Meyer, R. A.

    1986-01-01

    Rugged unit designed to operate in severe environment. Forcetransducer body designed for measurement of loads on specimens tested in hydrogen gas at temperatures up to 2,000 degree F (1,090 degree C). Body has symmetrical radial-shear-beam configuration and machined in one piece from bar stock.

  17. Strain-hardening in nano-structured single phase steels: mechanisms and control.

    Science.gov (United States)

    Bouaziz, O; Barbier, D

    2012-11-01

    The detrimental effect of grain size refinement on the strain hardening is highlighted in single phase steels. A physical based approach for understanding the underlying mechanisms is presented. In order to overcome this limitation a promising metallurgical route exploiting the thermal stability of mechanically induced twins in austenitic steels has been successfully applied to a stainless grade confirming the opportunity to get nano-structured alloys exhibiting high yield stress with high strain-hardening.

  18. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics.

    Science.gov (United States)

    Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T; Bohr, Tomas

    2015-07-01

    In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

  19. Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

    Science.gov (United States)

    Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T.; Bohr, Tomas

    2015-07-01

    In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006), 10.1103/PhysRevLett.97.154101] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

  20. Product management of making large pieces through Rapid Prototyping PolyJet® technology

    Science.gov (United States)

    Belgiu, G.; Cărăuşu, C.; Şerban, D.; Turc, C. G.

    2017-08-01

    The rapid prototyping process has already become a classic manufacturing process for parts and assemblies, either polymeric or metal parts. Besides the well-known advantages and disadvantages of the process, the use of 3D printers has a great inconvenience: the overall dimensions of the parts are limited. Obviously, there is a possibility to purchase a larger (and more expensive) 3D printer, but there are always larger pieces to be manufactured. One solution to this problem is the splitting of parts into several components that can be manufactured. The component parts can then be assembled in a single piece by known methods such as welding, gluing, screwing, etc. This paper shows our experience in making large pieces on the Strarasys® Objet24 printer, pieces larger than the tray sizes. The results obtained are valid for any 3D printer using the PolyJet® process.

  1. Mechanical characterization and single asperity scratch behaviour of dry zinc and manganese phosphate coatings

    NARCIS (Netherlands)

    Ernens, D.; de Rooij, M. B.; Pasaribu, H. R.; van Riet, E.J.; van Haaften, W.M.; Schipper, D. J.

    The goal of this study is to characterise the mechanical properties of zinc and manganese phosphate coatings before and after running in. The characterization is done with nano-indentation to determine the individual crystal hardness and single asperity scratch tests to investigate the deformation

  2. Mechanism of DNA–binding loss upon single-point mutation in p53

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    provides an excellent prototype system to elucidate the different mechanisms underlying the loss in DNA binding affinity and specificity upon single point mutation because over 50% of all human cancers involve p53 mutations, which occur mostly in the sequence–specific DNA–binding central domain (residues 102–292, ...

  3. Comparison of Numerical Modelling of Degradation Mechanisms in Single Mode Optical Fibre Using MATLAB and VPIphotonics

    Directory of Open Access Journals (Sweden)

    Jana Sajgalikova

    2015-01-01

    Full Text Available Mathematical models for description of physical phenomena often use the statistical description of the individual phenomena and solve those using suitable methods. If we want to develop numerical model of optical communication system based on transmission through single mode optical fibres, we need to consider whole series of phenomena that affect various parts of the system. In the single-mode optical fibre we often encounter influence of chromatic dispersion and nonlinear Kerr effects. By observing various different degradation mechanisms, every numerical model should have its own limits, which fulfil more detailed specification. It is inevitable to consider them in evaluation. In this paper, we focus on numerical modelling of degradation mechanisms in single-mode optical fibre. Numerical solution of non-linear Schroedinger equation is performed by finite difference method applied in MATLAB environment and split-step Fourier method, which is implemented by VPIphotonics software.

  4. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  5. Physics colloquium: Single-electron counting in quantum metrology and in statistical mechanics

    CERN Multimedia

    Geneva University

    2011-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92olé   Lundi 17 octobre 2011 17h00 - Ecole de Physique, Auditoire Stueckelberg PHYSICS COLLOQUIUM « Single-electron counting in quantum metrology and in statistical mechanics » Prof. Jukka Pekola Low Temperature Laboratory, Aalto University Helsinki, Finland   First I discuss the basics of single-electron tunneling and its potential applications in metrology. My main focus is in developing an accurate source of single-electron current for the realization of the unit ampere. I discuss the principle and the present status of the so-called single- electron turnstile. Investigation of errors in transporting electrons one by one has revealed a wealth of observations on fundamental phenomena in mesoscopic superconductivity, including individual Andreev...

  6. Surface dimpling on rotating work piece using rotation cutting tool

    Science.gov (United States)

    Bhapkar, Rohit Arun; Larsen, Eric Richard

    2015-03-31

    A combined method of machining and applying a surface texture to a work piece and a tool assembly that is capable of machining and applying a surface texture to a work piece are disclosed. The disclosed method includes machining portions of an outer or inner surface of a work piece. The method also includes rotating the work piece in front of a rotating cutting tool and engaging the outer surface of the work piece with the rotating cutting tool to cut dimples in the outer surface of the work piece. The disclosed tool assembly includes a rotating cutting tool coupled to an end of a rotational machining device, such as a lathe. The same tool assembly can be used to both machine the work piece and apply a surface texture to the work piece without unloading the work piece from the tool assembly.

  7. Contrast enhancement of mail piece images

    Science.gov (United States)

    Shin, Yong-Chul; Sridhar, Ramalingam; Demjanenko, Victor; Palumbo, Paul W.; Hull, Jonathan J.

    1992-08-01

    A New approach to contrast enhancement of mail piece images is presented. The contrast enhancement is used as a preprocessing step in the real-time address block location (RT-ABL) system. The RT-ABL system processes a stream of mail piece images and locates destination address blocks. Most of the mail pieces (classified into letters) show high contrast between background and foreground. As an extreme case, however, the seasonal greeting cards usually use colored envelopes which results in reduced contrast osured by an error rate by using a linear distributed associative memory (DAM). The DAM is trained to recognize the spectra of three classes of images: with high, medium, and low OCR error rates. The DAM is not forced to make a classification every time. It is allowed to reject as unknown a spectrum presented that does not closely resemble any that has been stored in the DAM. The DAM was fairly accurate with noisy images but conservative (i.e., rejected several text images as unknowns) when there was little ground and foreground degradations without affecting the nondegraded images. This approach provides local enhancement which adapts to local features. In order to simplify the computation of A and (sigma) , dynamic programming technique is used. Implementation details, performance, and the results on test images are presented in this paper.

  8. Enhanced mechanical properties of single-walled carbon nanotubes due to chemical functionalization.

    Science.gov (United States)

    He, X Q; Kuang, Y D; Chen, C Y; Li, G Q

    2009-05-27

    Recent studies have shown that the chemical functionalization of carbon nanotubes weakens most of their mechanical properties such as the critical buckling force under compression and the critical buckling moment under torsion. However, the mechanical properties including the critical bending curvature and the critical bending moment of single-walled carbon nanotubes can be improved after functionalization as shown in this paper. The molecular mechanics simulations reveal that there exists an optimum functionalization degree at which the critical curvatures of the functionalized carbon nanotubes reaches its maximum value. The critical curvatures of the carbon nanotubes increase with increasing functionalization degree below the optimum value, while the critical curvatures change little as the functionalization degree is beyond the optimum value. The influences of the bending directions and the aspect ratios of the functionalized carbon nanotubes are also examined via molecular mechanics simulations.

  9. Single-molecule folding mechanism of an EF-hand neuronal calcium sensor

    DEFF Research Database (Denmark)

    Heiðarsson, Pétur Orri; Otazo, Mariela R.; Bellucci, Luca

    2013-01-01

    EF-hand calcium sensors respond structurally to changes in intracellular Ca2+ concentration, triggering diverse cellular responses and resulting in broad interactomes. Despite impressive advances in decoding their structure-function relationships, the folding mechanism of neuronal calcium sensors...... is still elusive. We used single-molecule optical tweezers to study the folding mechanism of the human neuronal calcium sensor 1 (NCS1). Two intermediate structures induced by Ca2+ binding to the EF-hands were observed during refolding. The complete folding of the C domain is obligatory for the folding...

  10. DNA-cisplatin binding mechanism peculiarities studied with single molecule stretching experiments

    Science.gov (United States)

    Crisafuli, F. A. P.; Cesconetto, E. C.; Ramos, E. B.; Rocha, M. S.

    2012-02-01

    We propose a method to determine the DNA-cisplatin binding mechanism peculiarities by monitoring the mechanical properties of these complexes. To accomplish this task, we have performed single molecule stretching experiments by using optical tweezers, from which the persistence and contour lengths of the complexes can be promptly measured. The persistence length of the complexes as a function of the drug total concentration in the sample was used to deduce the binding data, from which we show that cisplatin binds cooperatively to the DNA molecule, a point which so far has not been stressed in binding equilibrium studies of this ligand.

  11. Crowding by a single bar: probing pattern recognition mechanisms in the visual periphery.

    Science.gov (United States)

    Põder, Endel

    2014-11-06

    Whereas visual crowding does not greatly affect the detection of the presence of simple visual features, it heavily inhibits combining them into recognizable objects. Still, crowding effects have rarely been directly related to general pattern recognition mechanisms. In this study, pattern recognition mechanisms in visual periphery were probed using a single crowding feature. Observers had to identify the orientation of a rotated T presented briefly in a peripheral location. Adjacent to the target, a single bar was presented. The bar was either horizontal or vertical and located in a random direction from the target. It appears that such a crowding bar has very strong and regular effects on the identification of the target orientation. The observer's responses are determined by approximate relative positions of basic visual features; exact image-based similarity to the target is not important. A version of the "standard model" of object recognition with second-order features explains the main regularities of the data. © 2014 ARVO.

  12. Investigation of Chirality Selection Mechanism of Single Walled Carbon Nanotube-3

    Science.gov (United States)

    2017-12-14

    paper as a result of the grant titled: Synthesis of CNT forest with narrow diameter distribution from the Fe ion implanted wafer, Carbon , vol. 123, pp...Jin Park, Seung Min Kim*, and Kun-Hong Lee*, “Synthesis of CNT forest with narrow diameter distribution from the Fe ion implanted wafer”, Carbon ...AFRL-AFOSR-JP-TR-2017-0078 Investigation of Chirality Selection Mechanism of Single-Walled Carbon Nanotube-3 Seun Min Kim KOREA INSTITUTE OF SCIENCE

  13. Adaptive kanban control mechanism for a single-stage hybrid system

    Science.gov (United States)

    Korugan, Aybek; Gupta, Surendra M.

    2002-02-01

    In this paper, we consider a hybrid manufacturing system with two discrete production lines. Here the output of either production line can satisfy the demand for the same type of product without any penalties. The interarrival times for demand occurrences and service completions are exponentially distributed i.i.d. variables. In order to control this type of manufacturing system we suggest a single stage pull type control mechanism with adaptive kanbans and state independent routing of the production information.

  14. Solar project description for Zien Mechanical Contractors-I single family residence, Milwaukee, Wisconsin

    Science.gov (United States)

    Beers, D.

    1980-02-01

    The Zien Mechanical site is a single family residence located in Milwaukee, Wisconsin. The home has two separate solar energy systems: an air system for space heating and cooling; a liquid system to preheat the potable hot water. The space heating and cooling system design and operation modes are described. The space heating system is designed to apply approximately 44 percent of the space heating requirements for the 1388 square foot residence. Engineering drawings are provided and the performance evaluation instrumentation is described.

  15. Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation

    Science.gov (United States)

    Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui

    2018-04-01

    The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n  >  2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n  >  2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n  =  2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.

  16. One-Piece Leak-Proof Battery

    Science.gov (United States)

    Verhoog, Roelof

    1999-03-23

    The casing of a leak-proof one-piece battery is made of a material comprising a mixture of at least a matrix based on polypropylene and an alloy of a polyamide and a polypropylene. The ratio of the matrix to the alloy is in the range 0.5 to 6 by weight. The alloy forms elongate arborescent inclusions in the matrix such that, on average, the largest dimension of a segment of the arborescence is at least twenty times the smallest dimension of the segment.

  17. Large Deflections Mechanical Analysis of a Suspended Single-Wall Carbon Nanotube under Thermoelectrical Loading

    Directory of Open Access Journals (Sweden)

    Assaf Ya'akobovitz

    2011-01-01

    Full Text Available Following the recent progress in integrating single-wall carbon nanotubes (SWCNTs into silicon-based micro-electromechanical systems (MEMS, new modeling tools are needed to predict their behavior under different loads, including thermal, electrical and mechanical. In the present study, the mechanical behavior of SWCNTs under thermoelectrical loading is analyzed using a large deflection geometrically nonlinear string model. The effect of the resistive heating was found to have a substantial influence on the SWCNTs behavior, including significant enhancement of the strain (up to the millistrains range and buckling due to the thermal expansion. The effect of local buckling sites was also studied and was found to enhance the local strain. The theoretical and numerical results obtained in the present study demonstrate the importance of resistive heating in the analysis of SWCNTs and provide an additional insight into the unique mechanics of suspended SWCNTs.

  18. Refractive predictability of a 3-piece intraocular lens platform versus its 1-piece counterpart.

    Science.gov (United States)

    Mednick, Zale D; Varma, Devesh K; Campos-Möller, Xavier; Ahmed, Iqbal Ike K

    2017-04-01

    To compare the refractive outcomes of a 3-piece acrylic intraocular lens (IOL) with its 1-piece counterpart after phacoemulsification with in-the-bag implantation. Retrospective chart review. One-hundred twenty-six eyes of 95 patients were analyzed in the study, including 60 eyes of 43 patients receiving a 3-piece IOL and 66 eyes of 52 patients receiving a 1-piece IOL. Randomized chart review of all patients who underwent uncomplicated phacoemulsification with in-the-bag IOL implantation with either a 3-piece hydrophobic acrylic IOL (Tecnis ZA9003) or a 1-piece hydrophobic acrylic IOL (Tecnis ZCB00) between 2006 and 2014 in a tertiary ophthalmology care centre in Mississauga, Ontario. Preoperative visual acuity and refraction, anterior chamber depth, axial length, IOL design and power, predicted refraction, postoperative visual acuity, and refraction were recorded. Mean absolute error was 0.40 ± 0.27 in the ZA9003 group and 0.39 ± 0.35 in the ZCB00 group, with no statistically significant difference between the 2 IOLs (p = 0.86). Mean arithmetic error was 0.11 ± 0.47 D in the ZA9003 group and 0.01 ± 0.47 D in the ZCB00 group (p = 0.019). In the ZA9003 group, 23 (38%), 42 (70%), and 52 (87%) of 60 eyes were within 0.25, 0.50, and 0.75 D, respectively, of predicted postoperative refraction. In the ZCB00 group, 32 (48%), 46 (70%), and 56 (85%) of 66 eyes were within 0.25, 0.50, and 0.75 D, respectively, of predicted postoperative refraction (p = 0.2836, p = 1.00, p = 0.8044). The ZA9003 and the ZCB00 have similar mean absolute error and thus appear to have similar refractive predictability. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  19. In vitro performance of one- and two-piece zirconia implant systems for anterior application.

    Science.gov (United States)

    Kammermeier, Armin; Rosentritt, Martin; Behr, Michael; Schneider-Feyrer, Sibylle; Preis, Verena

    2016-10-01

    To investigate the long-term in vitro performance and fracture resistance of one-piece and bonded two-piece zirconia implant systems for anterior application. Two groups of bonded two-piece zirconia (ZZB), four groups of one-piece zirconia (Z), and two groups of two-piece titanium (TTS, reference) implant systems were restored with identical monolithic zirconia crowns (n=10/group). Eight specimens per group were mounted at an angle of 135° in the chewing simulator and subjected to thermal cycling (TC:18,000 cycles; 5°/55°) and mechanical loading (ML:3.6×10(6) cycles; 100N) simulating an anterior situation. Fracture resistance and maximum bending stress were determined for specimens that survived aging and for two references per group after 24h water storage. SEM pictures were used for failure analysis. Data were statistically analysed (one-way-ANOVA, post-hoc Bonferroni, Kaplan-Meier-Log-Rank, α=0.05). A one-piece zirconia and a two-piece titanium implant system survived TCML without failures. Both bonded two-piece zirconia implant systems and a one-piece zirconia implant system totally failed (fractures of abutment or implant). Failure numbers of the other systems varied between 1× (1 group) and 5× (2 groups). Significantly different survival rates were found (Log-Rank-test: p=0.000). Maximum fracture forces/bending stresses varied significantly ( p=0.000) between 188.00±44.80N/381.02±80.15N/mm(2) and 508.67±107.00N/751.45±36.73N/mm(2). Mean fracture values after 24h water storage and TCML were not significantly different. Zirconia implant systems partly showed material defects or connection insufficiencies. Bonded two-piece systems had higher failure rates and lower fracture resistance than one-piece implants. Individual zirconia implant systems may be applied in anterior regions with limitations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Note onset deviations as musical piece signatures.

    Science.gov (United States)

    Serrà, Joan; Özaslan, Tan Hakan; Arcos, Josep Lluis

    2013-01-01

    A competent interpretation of a musical composition presents several non-explicit departures from the written score. Timing variations are perhaps the most important ones: they are fundamental for expressive performance and a key ingredient for conferring a human-like quality to machine-based music renditions. However, the nature of such variations is still an open research question, with diverse theories that indicate a multi-dimensional phenomenon. In the present study, we consider event-shift timing variations and show that sequences of note onset deviations are robust and reliable predictors of the musical piece being played, irrespective of the performer. In fact, our results suggest that only a few consecutive onset deviations are already enough to identify a musical composition with statistically significant accuracy. We consider a mid-size collection of commercial recordings of classical guitar pieces and follow a quantitative approach based on the combination of standard statistical tools and machine learning techniques with the semi-automatic estimation of onset deviations. Besides the reported results, we believe that the considered materials and the methodology followed widen the testing ground for studying musical timing and could open new perspectives in related research fields.

  1. Note onset deviations as musical piece signatures.

    Directory of Open Access Journals (Sweden)

    Joan Serrà

    Full Text Available A competent interpretation of a musical composition presents several non-explicit departures from the written score. Timing variations are perhaps the most important ones: they are fundamental for expressive performance and a key ingredient for conferring a human-like quality to machine-based music renditions. However, the nature of such variations is still an open research question, with diverse theories that indicate a multi-dimensional phenomenon. In the present study, we consider event-shift timing variations and show that sequences of note onset deviations are robust and reliable predictors of the musical piece being played, irrespective of the performer. In fact, our results suggest that only a few consecutive onset deviations are already enough to identify a musical composition with statistically significant accuracy. We consider a mid-size collection of commercial recordings of classical guitar pieces and follow a quantitative approach based on the combination of standard statistical tools and machine learning techniques with the semi-automatic estimation of onset deviations. Besides the reported results, we believe that the considered materials and the methodology followed widen the testing ground for studying musical timing and could open new perspectives in related research fields.

  2. Morphological and mechanical characterization of composite calcite/SWCNT-COOH single crystals.

    Science.gov (United States)

    Calvaresi, Matteo; Falini, Giuseppe; Pasquini, Luca; Reggi, Michela; Fermani, Simona; Gazzadi, Gian Carlo; Frabboni, Stefano; Zerbetto, Francesco

    2013-08-07

    A growing number of classes of organic (macro)molecular materials have been trapped into inorganic crystalline hosts, such as calcite single crystals, without significantly disrupting their crystalline lattices. Inclusion of an organic phase plays a key role in enhancing the mechanical properties of the crystals, which are believed to share structural features with biogenic minerals. Here we report the synthesis and mechanical characterization of composite calcite/SWCNT-COOH single crystals. Once entrapped into the crystals SWCNT-COOH appeared both as aggregates of entangled bundles and nanoropes. Their observation was possible only after crystal etching, fracture or FIB (focused ion beam) cross-sectioning. SWCNT-COOHs occupied a small volume fraction and were randomly distributed into the host crystal. They did not strongly affect the crystal morphology. However, although the Young's modulus of composite calcite/SWCNT-COOH single crystals was similar to that of pure calcite their hardness increased by about 20%. Thus, SWCNT-COOHs provide an obstacle against the dislocation-mediated propagation of plastic deformation in the crystalline slip systems, in analogy with the well-known hardness increase in fiber-reinforced composites.

  3. MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    V.S. Malyar

    2016-06-01

    Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.

  4. A Failure Criterion for Single-Walled Carbon Nanotubes Based on Molecular Mechanics

    Science.gov (United States)

    Avila, Antonio; Lacerda, Guilherme

    2008-03-01

    Single-walled carbon nanotubes (SWNT) are the natural choice for high performance materials. The problem, however, rises when the experimental data are compared against each other. The large variability of experimental data lead to development of a new set of numerical simulations called molecular mechanics, which is a ``symbiotic'' association of molecular dynamics and solid mechanics. This papers deals with a molecular mechanics simulations of single-walled carbon nanotubes. Three SWNT configurations and its combinations were simulated, i.e. armchair, zigzag and chiral. The failure criterion introduced is based on modified Morse's potential with dissociation energy of 124 Kcal/mol and an inflection point considered is around 13% of strain. The numerical data are in good agreement with data from Belytschko et al. (2002) where the failure occurred at 10.6% strain at 65.2 GPa of stress. To be able to identify the highest stress concentration region, one end of the SWNT all degrees-of-freedom were fixed and a prescribed axial displacement was applied at the opposite end. The Sadoc (chiral-chiral) configuration had the highest stress at the smallest chiral SWNT. For the Dunlap configuration (chiral-zigzag) the highest stress occurred at chiral part close to the pentagon location.

  5. Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

    Directory of Open Access Journals (Sweden)

    Riccardo Frisenda

    2015-07-01

    Full Text Available We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene (OPE3, while having different aurophilic anchoring groups: thiol (SAc, methyl sulfide (SMe, pyridyl (Py and amine (NH2. The focus of this paper is on the combined characterization of the electrical and mechanical properties determined by the anchoring groups. From conductance histograms we find that thiol anchored molecules provide the highest conductance; a single-level model fit to current–voltage characteristics suggests that SAc groups exhibit a higher electronic coupling to the electrodes, together with better level alignment than the other three groups. An analysis of the mechanical stability, recording the lifetime in a self-breaking method, shows that Py and SAc yield the most stable junctions while SMe form short-lived junctions. Density functional theory combined with non-equlibrium Green’s function calculations help in elucidating the experimental findings.

  6. Fractal dimension analysis of complexity in Ligeti piano pieces

    Science.gov (United States)

    Bader, Rolf

    2005-04-01

    Fractal correlation dimensional analysis has been performed with whole solo piano pieces by Gyrgy Ligeti at every 50ms interval of the pieces. The resulting curves of development of complexity represented by the fractal dimension showed up a very reasonable correlation with the perceptional density of events during these pieces. The seventh piece of Ligeti's ``Musica ricercata'' was used as a test case. Here, each new part of the piece was followed by an increase of the fractal dimension because of the increase of information at the part changes. The second piece ``Galamb borong,'' number seven of the piano Etudes was used, because Ligeti wrote these Etudes after studying fractal geometry. Although the piece is not fractal in the strict mathematical sense, the overall structure of the psychoacoustic event-density as well as the detailed event development is represented by the fractal dimension plot.

  7. Single-nary philosophy for non-linear study of mechanics of materials

    International Nuclear Information System (INIS)

    Tran, C.

    2005-01-01

    Non-linear study of mechanics of materials is formulated in this paper as a problem of meta-intelligent system analysis. Non-linearity will be singled out as an important concept for understanding of high-order complex systems. Through single-nary thinking, which will be represented in this work, we introduce a modification of Aristotelian philosophy using modal logic and multi-valued logic (these logics we call 'high-order' logic). Next, non-linear cause - effect relations are expressed through non-additive measures and multiple-information aggregation principles based on fuzzy integration. The study of real time behaviors, required experiences and intuition, will be realized using truth measures (non-additive measures) and a procedure for information processing in intelligence levels. (author)

  8. Rings and rackets from single-wall carbon nanotubes: manifestations of mesoscale mechanics.

    Science.gov (United States)

    Wang, Yuezhou; Semler, Matthew R; Ostanin, Igor; Hobbie, Erik K; Dumitrică, Traian

    2014-11-21

    We combine experiments and distinct element method simulations to understand the stability of rings and rackets formed by single-walled carbon nanotubes assembled into ropes. Bending remains a soft deformation mode in ropes because intra-rope sliding of the constituent nanotubes occurs with ease. Our simulations indicate that the formation of these aggregates can be attributed to the mesoscopic mechanics of entangled nanotubes and to the sliding at the contacts. Starting from the single-walled carbon nanotubes, the sizes of the rings and rackets' heads increase with the rope diameter, indicating that the stability of the experimental aggregates can be largely explained by the competition between bending and van der Waals adhesion energies. Our results and simulation method should be useful for understanding nanoscale fibers in general.

  9. Effect of cobalt on microstructural parameters and mechanical properties of Ni-base single crystal superalloys

    International Nuclear Information System (INIS)

    Suzuki, Takanobu; Imai, Hachiro; Yokokawa, Tadaharu; Kobayashi, Toshiharu; Koizumi, Yutaka; Harada, Hiroshi

    2007-01-01

    The alloying effect of Cobalt (Co) to microstructural parameters and mechanical properties, such as partitioning ratios of alloying elements and creep strength, of Re-bearing Ni-base single crystal superalloys have been investigated. The second generation single crystal superalloys, TMS-82+, Ni-7.8Co-4.9Cr-1.9Mo-8.7W-5.3Al-6.0Ta-2.4Re-0.1Hf, in mass% (8Co) was compared to a Co-free (0Co) and 15 mass% Co (15Co) alloy which had the same chemical composition as TMS-82+ except that Co was changed. It was shown that the partitioning ratios of alloying elements trend to k(=X γ /X' γ )=1, as the content of Co was increased. Furthermore, it was found that there was suitable content of Co for the creep strength under various temperature-stress conditions. (author)

  10. Investigation on crystalline perfection, mechanical, piezoelectric and ferroelectric properties of L-tartaric acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, G. Senthil, E-mail: nanosen@gmail.com; Ramasamy, P., E-mail: nanosen@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Tamilnadu - 603110 (India)

    2014-04-24

    Polar organic nonlinear optical material, L-tartaric acid single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallized in monoclinic system with space group P2{sub 1}. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal quality is good and free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. Piezoelectric d{sub 33} co-efficient for the crystal has been examined and its value is 47 pC/N. The ferroelectric behaviour of the crystal was analyzed by polarization-electric field hysteresis loop measurement.

  11. Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

    OpenAIRE

    Theebhan Mogana; Long Chua Yaw; Tiong Tay Tee

    2016-01-01

    The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar ray...

  12. Mechanical behavior study of single cell contraction by digital image correlation technique

    Science.gov (United States)

    Huang, Jianyong; Wu, Jia; Qin, Lei; Zhu, Tao; Xiong, Chunyang; Zhang, Youyi; Fang, Jing

    2008-11-01

    Precise determination of cellular traction forces has important significance in assessing cellular mechanical characteristic on micro/nano scale. Elastic substrate method is a useful way to study cellular traction forces, in which the cells are cultured on elastic gel substrate marked by randomly embedding fluorescent microbeads and they exert mechanical forces on the film to cause deformation of the substrate material. In this paper, we investigate the acquisition of deformation field induced by single cardiac myocyte by using digital image correlation (DIC) technique. In view of the fact that cellular force restoration is essentially an ill-posed inverse problem, which implies that the force reconstruction is susceptible to the input displacement noise, we develop a novel optimal filtering scheme in two-dimensional Fourier space to restrain displacement noise amplification. Experiments of traction force recovery for a real cardiac myocyte indicate the optimal scheme in combination with the DIC method enables us to reconstruct cellular traction fields with high accuracy.

  13. Transcending the biomarker mindset: deciphering disease mechanisms at the single cell level.

    Science.gov (United States)

    Danna, Erika A; Nolan, Garry P

    2006-02-01

    The application of proteomics to disease research promises to enhance the understanding and treatment of many human maladies through the identification of molecular profiles associated with each disease. However, although much is made of the utility of molecular signatures as markers of disease state, insufficient emphasis is often placed on the simultaneous need for biological mechanism inquiry. Focused and detailed analyses of disease-associated signaling networks have the potential to be more mechanistically informative than large-scale proteomic profiling approaches, providing insight into the cellular processes involved in pathogenesis, disease progression and therapeutic resistance; while still providing diagnostic or clinical management direction. Phospho-specific flow cytometry provides a method for the analysis of pathological signaling networks, enabling the investigation of disease mechanisms at the single-cell level.

  14. Molecular scale buckling mechanics in individual aligned single-wall carbon nanotubes on elastomeric substrates.

    Science.gov (United States)

    Khang, Dahl-Young; Xiao, Jianliang; Kocabas, Coskun; MacLaren, Scott; Banks, Tony; Jiang, Hanqing; Huang, Yonggang Y; Rogers, John A

    2008-01-01

    We have studied the scaling of controlled nonlinear buckling processes in materials with dimensions in the molecular range (i.e., approximately 1 nm) through experimental and theoretical studies of buckling in individual single-wall carbon nanotubes on substrates of poly(dimethylsiloxane). The results show not only the ability to create and manipulate patterns of buckling at these molecular scales, but also, that analytical continuum mechanics theory can explain, quantitatively, all measurable aspects of this system. Inverse calculation applied to measurements of diameter-dependent buckling wavelengths yields accurate values of the Young's moduli of individual SWNTs. As an example of the value of this system beyond its use in this type of molecular scale metrology, we implement parallel arrays of buckled SWNTs as a class of mechanically stretchable conductor.

  15. Influence of cobalt, tantalum, and tungsten on the microstructure and mechanical properties of superalloy single crystals

    International Nuclear Information System (INIS)

    Nathal, M.V.; Ebert, L.J.

    1982-01-01

    The influence of Co, Ta, and W on the microstructure and mechanical properties of nickel base super-alloy single crystals was investigated. A matrix of alloys was based on Mar-M 247 stripped of C, B, Zr, and Hf. The microstructures of the alloys were examined using optical and electron microscopy, phase extraction, X-ray diffraction, and differential thermal analysis. Tensile and creep-rupture tests were performed at 1000 C. An increase in tensile and creep strength resulted when Co was removed from alloys containing high refractory metal contents, but Co effects were negligible for alloys with lower refractory metal levels. In the composition range studied, W was more effective than Ta in increasing the creep resistance. The mechanical properties are discussed in relation to the microstructures of the alloys

  16. Influence of cobalt, tantalum, and tungsten on the microstructure and mechanical properties of superalloy single crystals

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1982-01-01

    The influence of Co, Ta, and W on the microstructure and mechanical properties of nickel base super-alloy single crystals was investigated. A matrix of alloys was based on Mar-M 247 stripped of C, B, Zr, and Hf. The microstructures of the alloys were examined using optical and electron microscopy, phase extraction, X-ray diffraction, and differential thermal analysis. Tensile and creep-rupture tests were performed at 1000 C. An increase in tensile and creep strength resulted when Co was removed from alloys containing high refractory metal contents, but Co effects were negligible for alloys with lower refractory metal levels. In the composition range studied, W was more effective than Ta in increasing the creep resistance. The mechanical properties are discussed in relation to the microstructures of the alloys.

  17. Experimental studies of the dynamic mechanical response of a single polymer chain

    DEFF Research Database (Denmark)

    Thormann, Esben; Evans, Drew R.; Craig, Vincent S. J.

    2006-01-01

    The high-frequency and low-amplitude dynamic mechanical response from a single poly(vinyl alcohol) chain was investigated. Modification of a commercial atomic force microscope enabled high-frequency and low-amplitude periodic deformations of polymer chains during extension to be performed...... mechanical response from poly(vinyl alcohol) does not differ from its static response. This result is not unexpected as poly(vinyl alcohol) is a highly flexible polymer with intramolecular relaxation processes taking place on a short time scale. The choice of a polymer with a fast relaxation allows its...... static properties to be recovered from the dynamic measurements and enables the method suggested in this paper for decoupling the polymer response from the hydrodynamic response to be validated....

  18. Mechanics governs single-cell signaling and multi-cell robustness in biofilm infections

    Science.gov (United States)

    Gordon, Vernita

    In biofilms, bacteria and other microbes are embedded in extracellular polymers (EPS). Multiple types of EPS can be produced by a single bacterial strain - the reasons for this redundancy are not well-understood. Our work suggests that different polymers may confer distinct mechanical benefits. Our model organism is Pseudomonas aeruginosa, an opportunistic human pathogen that forms chronic biofilm infections associated with increased antibiotic resistance and evasion of the immune defense. Biofilms initiate when bacteria attach to a surface, sense the surface, and change their gene expression. Changes in gene expression are regulated by a chemical signal, cyclic-di-GMP. We find that one EPS material, called ``PEL,'' enhances surface sensing by increasing mechanical coupling of single bacteria to the surface. Measurements of bacterial motility suggest that PEL may increase frictional interactions between the surface and the bacteria. Consistent with this, we show that bacteria increase cyclic-di-GMP signaling in response to mechanical shear stress. Mechanosensing has long been known to be important to the function of cells in higher eukaryotes, but this is one of only a handful of studies showing that bacteria can sense and respond to mechanical forces. For the mature biofilm, the embedding polymer matrix can protect bacteria both chemically and mechanically. P. aeruginosa infections in the cystic fibrosis (CF) lung often last for decades, ample time for the infecting strain(s) to evolve. Production of another EPS material, alginate, is well-known to tend to increase over time in CF infections. Alginate chemically protects biofilms, but also makes them softer and weaker. Recently, it is being increasingly recognized that bacteria in chronic CF infections also evolve to increase PSL production. We use oscillatory bulk rheology to determine the unique contributions of EPS materials to biofilm mechanics. Unlike alginate, increased PSL stiffens biofilms. Increasing both

  19. A new piece of the puzzle

    CERN Multimedia

    2005-01-01

    The team responsible for the installation of the hadronic calorimeter's central barrel after completion of the assembly work. Assembly of the great ATLAS puzzle continues underground. On 10 December, the final module of the central barrel of the tile hadronic calorimeter was assembled. This piece of the tile calorimeter had already been assembled above ground during a "dress rehearsal" in 2003 (see Bulletin no 46/2003, 10 November 2003). The hadronic calorimeter's two other barrels, the so-called "extended barrels", remain to be assembled with this first central barrel, which now surrounds the electromagnetic calorimeter barrel that was lowered into the cavern at the end of October. At the end of November, the second of the eight barrel toroid coils was also installed.

  20. Two-piece hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Subramaniam Elangovan

    2011-01-01

    Full Text Available There are various types of obturator fabrication achievable by prosthodontist. Maxillectomy, which is a term used by head and neck surgeons and prosthodontists to describe the partial or total removal of the maxilla in patients suffering from benign or malignant neoplasms is a defect for which to provide an effective obturator is a difficult task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. Speech is often unintelligible as a result of the marked defects in articulation and nasal resonance. This paper describes how to achieve the goal for esthetics and phonetics and also describes the fabrication of a hollow obturator by two piece method, which is simple and maybe used as definitive obturator for maximum comfort of the patient.

  1. Identification of two-step chemical mechanisms using small temperature oscillations and a single tagged species.

    Science.gov (United States)

    Closa, F; Gosse, C; Jullien, L; Lemarchand, A

    2015-05-07

    In order to identify two-step chemical mechanisms, we propose a method based on a small temperature modulation and on the analysis of the concentration oscillations of a single tagged species involved in the first step. The thermokinetic parameters of the first reaction step are first determined. Then, we build test functions that are constant only if the chemical system actually possesses some assumed two-step mechanism. Next, if the test functions plotted using experimental data are actually even, the mechanism is attributed and the obtained constant values provide the rate constants and enthalpy of reaction of the second step. The advantage of the protocol is to use the first step as a probe reaction to reveal the dynamics of the second step, which can hence be relieved of any tagging. The protocol is anticipated to apply to many mechanisms of biological relevance. As far as ligand binding is considered, our approach can address receptor conformational changes or dimerization as well as competition with or modulation by a second partner. The method can also be used to screen libraries of untagged compounds, relying on a tracer whose concentration can be spectroscopically monitored.

  2. 3D Thermal and Mechanical Analysis of a Single Event Burnout

    Science.gov (United States)

    Peretti, Gabriela; Demarco, Gustavo; Romero, Eduardo; Tais, Carlos

    2015-08-01

    This paper presents a study related to thermal and mechanical behavior of power DMOS transistors during a Single Event Burnout (SEB) process. We use a cylindrical heat generation region for emulating the thermal and mechanical phenomena related to the SEB. In this way, it is avoided the complexity of the mathematical treatment of the ion-device interaction. This work considers locating the heat generation region in positions that are more realistic than the ones used in previous work. For performing the study, we formulate and validate a new 3D model for the transistor that maintains the computational cost at reasonable level. The resulting mathematical models are solved by means of the Finite Element Method. The simulations results show that the failure dynamics is dominated by the mechanical stress in the metal layer. Additionally, the time to failure depends on the heat source position, for a given power and dimension of the generation region. The results suggest that 3D modeling should be considered for a detailed study of thermal and mechanical effects induced by SEBs.

  3. The Single Supervisory Mechanism: the Building Pillar of the European Banking Union

    Directory of Open Access Journals (Sweden)

    Luigi Chiarella

    2016-07-01

    Full Text Available One of the lessons learned from the 2008 financial crisis is that when a bank in Europe goes into trouble the ensuing effects can reach far beyond the immediate threat to its depositors and shareholders. In particular, the crisis has revealed the extent to which irresponsible behavior in the banking sector could undermine the foundations of the financial system and threaten the real economy, turning a banking crisis into a sovereign debt crisis as occurred in the eurozone in 2011. In response to this lesson, Member States first tried to address the systemic fragility of their banking systems through national policy tools, but countries that share a common currency and are more interdependent required more integrated responses. Therefore, at the euro area summit in June 2012, the European Council agreed to break the vicious circle between banks and sovereign debt and decided to create a banking union that would allow a centralized supervision for banks in the euro area through a newly established Single Supervisory Mechanism (SSM and a centralized resolution scheme. The SSM became operational in November 2014 and represents the building pillar of the banking union. The purpose of this paper is then to provide, after a brief description of the background (Par. 1, an analysis of the Single Supervisory Mechanism, illustrating its functioning (Par. 2, then focusing on the position and the powers of the ECB within it (Par. 3 and finally pointing out some remarks on the potential weaknesses of the new regime (Par. 4.

  4. Single and competitive adsorption of OMPs by carbon nanotubes - mechanism and fitting models

    Science.gov (United States)

    Kamińska, Gabriela; Dudziak, Mariusz; Bohdziewicz, Jolanta; Kudlek, Edyta

    2017-11-01

    The adsorption of three organic micropollutants (diclofenac - DFN, pentachlorophenol - PCP and octylphenol - OP) on two kinds of carbon nanotubes (single walled carbon nanotubes - SWCNT and single walled carbon nanotubes with amine group - SWCNT-NH2) was investigated, in single and bicomponent solution at pH 5. SWCNT-NH2 had three times lower specific surface area than SWCNT. Significant differences were observed in sorption capacity of SWCNT and SWCNT-NH2 for given chemicals. The sorption uptake changes in the following order: OP > PCP > DFN for SWCNT and DFN > PCP > OP for SWCNT-NH2. A few times higher adsorption of OP on SWCNT came from low OP solubility in water in comparison to PCP and DFN. While, higher adsorption of DFN and PCP on SWCNT-NH2 was a result of electrostatic attraction between dissociated form of these chemicals and positively charged SWCNT-NH2 at pH 5. In adsorption from bicomponent solution, significant competition was observed between PCP and DFN due to similar adsorption mechanism on SWCNT-NH2. Opposite tendency was observed for SWCNT, DFN did not greatly affect adsorption of PCP and OP since they were very easily absorbable by sigma-sigma interaction.

  5. Single and competitive adsorption of OMPs by carbon nanotubes – mechanism and fitting models

    Directory of Open Access Journals (Sweden)

    Kamińska Gabriela

    2017-01-01

    Full Text Available The adsorption of three organic micropollutants (diclofenac – DFN, pentachlorophenol – PCP and octylphenol – OP on two kinds of carbon nanotubes (single walled carbon nanotubes – SWCNT and single walled carbon nanotubes with amine group – SWCNT-NH2 was investigated, in single and bicomponent solution at pH 5. SWCNT-NH2 had three times lower specific surface area than SWCNT. Significant differences were observed in sorption capacity of SWCNT and SWCNT-NH2 for given chemicals. The sorption uptake changes in the following order: OP > PCP > DFN for SWCNT and DFN > PCP > OP for SWCNT-NH2. A few times higher adsorption of OP on SWCNT came from low OP solubility in water in comparison to PCP and DFN. While, higher adsorption of DFN and PCP on SWCNT-NH2 was a result of electrostatic attraction between dissociated form of these chemicals and positively charged SWCNT-NH2 at pH 5. In adsorption from bicomponent solution, significant competition was observed between PCP and DFN due to similar adsorption mechanism on SWCNT-NH2. Opposite tendency was observed for SWCNT, DFN did not greatly affect adsorption of PCP and OP since they were very easily absorbable by sigma-sigma interaction.

  6. Free vibration analysis of single-walled boron nitride nanotubes based on a computational mechanics framework

    Science.gov (United States)

    Yan, J. W.; Tong, L. H.; Xiang, Ping

    2017-12-01

    Free vibration behaviors of single-walled boron nitride nanotubes are investigated using a computational mechanics approach. Tersoff-Brenner potential is used to reflect atomic interaction between boron and nitrogen atoms. The higher-order Cauchy-Born rule is employed to establish the constitutive relationship for single-walled boron nitride nanotubes on the basis of higher-order gradient continuum theory. It bridges the gaps between the nanoscale lattice structures with a continuum body. A mesh-free modeling framework is constructed, using the moving Kriging interpolation which automatically satisfies the higher-order continuity, to implement numerical simulation in order to match the higher-order constitutive model. In comparison with conventional atomistic simulation methods, the established atomistic-continuum multi-scale approach possesses advantages in tackling atomic structures with high-accuracy and high-efficiency. Free vibration characteristics of single-walled boron nitride nanotubes with different boundary conditions, tube chiralities, lengths and radii are examined in case studies. In this research, it is pointed out that a critical radius exists for the evaluation of fundamental vibration frequencies of boron nitride nanotubes; opposite trends can be observed prior to and beyond the critical radius. Simulation results are presented and discussed.

  7. Modeling single molecule junction mechanics as a probe of interface bonding

    Science.gov (United States)

    Hybertsen, Mark S.

    2017-03-01

    Using the atomic force microscope based break junction approach, applicable to metal point contacts and single molecule junctions, measurements can be repeated thousands of times resulting in rich data sets characterizing the properties of an ensemble of nanoscale junction structures. This paper focuses on the relationship between the measured force extension characteristics including bond rupture and the properties of the interface bonds in the junction. A set of exemplary model junction structures has been analyzed using density functional theory based calculations to simulate the adiabatic potential surface that governs the junction elongation. The junction structures include representative molecules that bond to the electrodes through amine, methylsulfide, and pyridine links. The force extension characteristics are shown to be most effectively analyzed in a scaled form with maximum sustainable force and the distance between the force zero and force maximum as scale factors. Widely used, two parameter models for chemical bond potential energy versus bond length are found to be nearly identical in scaled form. Furthermore, they fit well to the present calculations of N-Au and S-Au donor-acceptor bonds, provided no other degrees of freedom are allowed to relax. Examination of the reduced problem of a single interface, but including relaxation of atoms proximal to the interface bond, shows that a single-bond potential form renormalized by an effective harmonic potential in series fits well to the calculated results. This allows relatively accurate extraction of the interface bond energy. Analysis of full junction models shows cooperative effects that go beyond the mechanical series inclusion of the second bond in the junction, the spectator bond that does not rupture. Calculations for a series of diaminoalkanes as a function of molecule length indicate that the most important cooperative effect is due to the interactions between the dipoles induced by the donor

  8. Hip-abductor fatigue and single-leg landing mechanics in women athletes.

    Science.gov (United States)

    Patrek, Mary F; Kernozek, Thomas W; Willson, John D; Wright, Glenn A; Doberstein, Scott T

    2011-01-01

    Reduced hip-abductor strength and muscle activation may be associated with altered lower extremity mechanics, which are thought to increase the risk for anterior cruciate ligament injury. However, experimental evidence supporting this relationship is limited. To examine the changes in single-leg landing mechanics and gluteus medius recruitment that occur after a hip-abductor fatigue protocol. Descriptive laboratory study. Twenty physically active women (age  =  21.0 ± 1.3 years). Participants were tested before (prefatigue) and after (postfatigue) a hip-abductor fatigue protocol consisting of repetitive side-lying hip abduction. Outcome measures included sagittal-plane and frontal-plane hip and knee kinematics at initial contact and at 60 milliseconds after initial contact during 5 single-leg landings from a height of 40 cm. Peak hip and knee sagittal-plane and frontal-plane joint moments during this time interval were also analyzed. Measures of gluteus medius activation, including latency, peak amplitude, and integrated signal, were recorded. A small (hip-abduction angle at initial contact and a small (hip at initial contact or at 60 milliseconds after initial contact. Peak external knee-adduction moment decreased 27% and peak hip adduction moment decreased 24% during the postfatigue landing condition. Gluteus medius activation was delayed after the protocol, but no difference in peak or integrated signal was seen during the landing trials. Changes observed during single-leg landings after hip-abductor fatigue were not generally considered unfavorable to the integrity of the anterior cruciate ligament. Further work may be justified to study the role of hip-abductor activation in protecting the knee during landing.

  9. Mobility-limiting mechanisms in single and dual channel strained Si/SiGe MOSFETs

    International Nuclear Information System (INIS)

    Olsen, S.H.; Dobrosz, P.; Escobedo-Cousin, E.; Bull, S.J.; O'Neill, A.G.

    2005-01-01

    Dual channel strained Si/SiGe CMOS architectures currently receive great attention due to maximum performance benefits being predicted for both n- and p-channel MOSFETs. Epitaxial growth of a compressively strained SiGe layer followed by tensile strained Si can create a high mobility buried hole channel and a high mobility surface electron channel on a single relaxed SiGe virtual substrate. However, dual channel n-MOSFETs fabricated using a high thermal budget exhibit compromised mobility enhancements compared with single channel devices, in which both electron and hole channels form in strained Si. This paper investigates the mobility-limiting mechanisms of dual channel structures. The first evidence of increased interface roughness due to the introduction of compressively strained SiGe below the tensile strained Si channel is presented. Interface corrugations degrade electron mobility in the strained Si. Roughness measurements have been carried out using AFM and TEM. Filtering AFM images allowed roughness at wavelengths pertinent to carrier transport to be studied and the results are in agreement with electrical data. Furthermore, the first comparison of strain measurements in the surface channels of single and dual channel architectures is presented. Raman spectroscopy has been used to study channel strain both before and after processing and indicates that there is no impact of the buried SiGe layer on surface macrostrain. The results provide further evidence that the improved performance of the single channel devices fabricated using a high thermal budget arises from improved surface roughness and reduced Ge diffusion into the Si channel

  10. Mechanical Revascularization for Acute Ischemic Stroke: A Single-Center, Retrospective Analysis

    International Nuclear Information System (INIS)

    Jeromel, Miran; Milosevic, Z. V.; Kocijancic, I. J.; Lovric, D.; Svigelj, V.; Zvan, B.

    2013-01-01

    BackgroundEndovascular mechanical revascularization (thrombectomy) is an increasingly used method for intracranial large vessel recanalization in acute stroke. The purpose of the study was to analyze the recanalization rate, clinical outcome, and complication rate in our stroke patients treated with mechanical revascularization. A total of 57 patients with large vessel stroke (within 3 h for anterior and 12 h for posterior circulation) were treated with mechanical revascularization at a single center during 24 months. The primary goal of endovascular treatment using different mechanical devices was recanalization of the occluded vessel. Recanalization rate (reported as thrombolysis in cerebral infarction [TICI] score), clinical outcome (reported as National Institutes of Health Stroke Scale [NIHSS] score and modified Rankin scale [mRS] score), as well as periprocedural complications were analyzed. The mean age of the patients was 63.1 ± 12.9 years, with baseline median NIHSS score of 14 (interquartile range, 9.5–19). Successful recanalization (TICI 2b or 3) was achieved in 41 (72 %) patients. Twenty patients (35 %) presented with favorable outcome (mRS ≤2) 30 days after stroke. Overall, significant neurological improvement (≥4 NIHSS point reduction) occurred in 36 (63 %) patients. A clinically significant procedure-related adverse events (vessel disruption, peri/postprocedural intracranial bleeding) defined with decline in NIHSS of ≥4 or death occurred in three (5 %) patients. The study showed a high recanalization rate with improved clinical outcome and a low rate of periprocedural complications in our stroke patients treated with mechanical revascularization. Therefore, we could conclude that endovascular revascularization (primary or in combination with a bridging thrombolysis) was an effective and safe procedure for intracranial large vessel recanalization in acute stroke.

  11. Two-piece cryopreserved tracheal allotransplantation: an experimental study.

    Science.gov (United States)

    Iyikesici, Tuncel; Tuncozgur, Bulent; Sanli, Maruf; Isik, Ahmet Feridun; Meteroglu, Fatih; Elbeyli, Levent

    2009-10-01

    For successful reconstruction with tracheal allotransplants following long tracheal resections, problems related to the preservation and vascularisation of the tracheal graft have to be solved. In this study, instead of using a long-segment single-piece graft, we used a graft that has been split into two. The aim was to use this graft after cryopreservation in order to ease neo-vascularisation and to maintain tracheal integrity by transplanting it to two separate regions of the dog cervical trachea. This experimental study was conducted in animal laboratories of the medical school on 11 half-blood dogs. The trachea obtained from the first dog was 8 cm in length; it was split into two pieces of 4 cm each and stored in the preservation solution at -80 degrees C for 4 weeks. Following this, the dog was sacrificed. Two 2 cm portions of cervical trachea were excised from the second dog. These parts were then reconstructed with two tracheal grafts of the same length as the cryopreserved ones. Ten dogs that were grouped into five groups of two dogs each underwent the same procedure. The subjects had a bronchoscopic evaluation on the third postoperative week. Anastomosis regions of the test tracheas were resected to be examined histopathologically. Seven subjects were found to have third-degree obstructions during bronchoscopy; two had close to fourth-degree obstructions. In the histopathological examination, contrary to the findings of the bronchoscopies, 75% of the anastomoses had intact epithelium. The cartilage was seen to have well-preserved structural characteristics in all the anastomoses. Twelve anastomoses had moderate, seven mild and one had severe inflammation. All anastomoses had either good or very good level of vascularisation. The integrity of the tracheal epithelium can be maintained with cryopreservation and split anastomosis technique. The cartilage preserves its structural characteristics despite losing its viability, thereby offering an advantage to

  12. Field electron emission characteristics and physical mechanism of individual single-layer graphene.

    Science.gov (United States)

    Xiao, Zhiming; She, Juncong; Deng, Shaozhi; Tang, Zikang; Li, Zhibing; Lu, Jianming; Xu, Ningsheng

    2010-11-23

    Due to its difficulty, experimental measurement of field emission from a single-layer graphene has not been reported, although field emission from a two-dimensional (2D) regime has been an attractive topic. The open surface and sharp edge of graphene are beneficial for field electron emission. A 2D geometrical effect, such as massless Dirac fermion, can lead to new mechanisms in field emission. Here, we report our findings from in situ field electron emission characterization on an individual singe-layer graphene and the understanding of the related mechanism. The measurement of field emission from the edges was done using a microanode probe equipped in a scanning electron microscope. We show that repeatable stable field emission current can be obtained after a careful conditioning process. This enables us to examine experimentally the typical features of the field emission from a 2D regime. We plot current versus applied field data, respectively, in ln(I/E(3/2)) ∼ 1/E and ln(I/E(3)) ∼ 1/E(2) coordinates, which have recently been proposed for field emission from graphene in high- and low-field regimes. It is observed that the plots all exhibit an upward bending feature, revealing that the field emission processes undergo from a low- to high-field transition. We discuss with theoretical analysis the physical mechanism responsible for the new phenomena.

  13. A robust single-beam optical trap for a gram-scale mechanical oscillator.

    Science.gov (United States)

    Altin, P A; Nguyen, T T-H; Slagmolen, B J J; Ward, R L; Shaddock, D A; McClelland, D E

    2017-11-06

    Precise optical control of microscopic particles has been mastered over the past three decades, with atoms, molecules and nano-particles now routinely trapped and cooled with extraordinary precision, enabling rapid progress in the study of quantum phenomena. Achieving the same level of control over macroscopic objects is expected to bring further advances in precision measurement, quantum information processing and fundamental tests of quantum mechanics. However, cavity optomechanical systems dominated by radiation pressure - so-called 'optical springs' - are inherently unstable due to the delayed dynamical response of the cavity. Here we demonstrate a fully stable, single-beam optical trap for a gram-scale mechanical oscillator. The interaction of radiation pressure with thermo-optic feedback generates damping that exceeds the mechanical loss by four orders of magnitude. The stability of the resultant spring is robust to changes in laser power and detuning, and allows purely passive self-locking of the cavity. Our results open up a new way of trapping and cooling macroscopic objects for optomechanical experiments.

  14. Dynamic mechanical analysis of single walled carbon nanotubes/polymethyl methacrylate nanocomposite films

    International Nuclear Information System (INIS)

    Badawi, Ali; Al Hosiny, N.

    2015-01-01

    Dynamic mechanical properties of nanocomposite films with different ratios of single walled carbon nanotubes/polymethyl methacrylate (SWCNTs/PMMA) are studied. Nanocomposite films of different ratios (0, 0.5, 1.0, and 2.0 weight percent (wt%)) of SWCNTs/PMMA are fabricated by using a casting technique. The morphological and structural properties of both SWCNT powder and SWCNTs/PMMA nanocomposite films are investigated by using a high resolution transmission electron microscope and x-ray diffractometer respectively. The mechanical properties including the storage modulus, loss modulus, loss factor (tan δ) and stiffness of the nanocomposite film as a function of temperature are recorded by using a dynamic mechanical analyzer at a frequency of 1 Hz. Compared with pure PMMA film, the nanocomposite films with different ratios of SWCNTs/PMMA are observed to have enhanced storage moduli, loss moduli and high stiffness, each of which is a function of temperature. The intensity of the tan δ peak for pure PMMA film is larger than those of the nanocomposite films. The glass transition temperature (T g ) of SWCNTs/PMMA nanocomposite film shifts towards the higher temperature side with respect to pure PMMA film from 91.2 °C to 99.5 °C as the ratio of SWCNTs/PMMA increases from 0 to 2.0 wt%. (paper)

  15. MEMS measurements of single cell stiffness decay due to cyclic mechanical loading.

    Science.gov (United States)

    Barazani, Bruno; Warnat, Stephan; MacIntosh, Andrew J; Hubbard, Ted

    2017-08-25

    The goal of this study was to measure the mechanical stiffness of individual cells and to observe changes due to the application of repeated cell mechanical loads. 28 single baker's yeast cells (Saccharomyces cerevisiae) were fatigue tested and had their stiffness measured during repetitive loading cycles performed by a MEMS squeezer in aqueous media. Electrothermal micro-actuators compressed individual cells against a reference back spring; cell and spring motions were measured using a FFT image analysis technique with ~10 nm resolution. Cell stiffness was calculated based on measurements of cell elongation vs. applied force which resulted in stiffness values in the 2-10 N/m range. The effect of increased force was studied for cells mechanically cycled 37 times. Cell stiffness decreased as the force and the cycle number increased. After 37 loading cycles (~4 min), forces of 0.24, 0.29, 0.31, and 0.33 μN caused stiffness drops of 5%, 13%, 31% and 41% respectively. Cells force was then set to 0.29 μN and cells were tested over longer runs of 118 and 268 cycles. After 118 cycles (~12 min) cells experienced an average stiffness drop of 68%. After 268 cycles (~25 min) cells had a stiffness drop of 77%, and appeared to reach a stiffness plateau of 20-25% of the initial stiffness after approximately 200 cycles.

  16. Computational exploration of single-protein mechanics by steered molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sotomayor, Marcos [Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio (United States)

    2015-12-31

    Hair cell mechanotransduction happens in tens of microseconds, involves forces of a few picoNewtons, and is mediated by nanometer-scale molecular conformational changes. As proteins involved in this process become identified and their high resolution structures become available, multiple tools are being used to explore their “single-molecule responses” to force. Optical tweezers and atomic force microscopy offer exquisite force and extension resolution, but cannot reach the high loading rates expected for high frequency auditory stimuli. Molecular dynamics (MD) simulations can reach these fast time scales, and also provide a unique view of the molecular events underlying protein mechanics, but its predictions must be experimentally verified. Thus a combination of simulations and experiments might be appropriate to study the molecular mechanics of hearing. Here I review the basics of MD simulations and the different methods used to apply force and study protein mechanics in silico. Simulations of tip link proteins are used to illustrate the advantages and limitations of this method.

  17. PolyMUMPs MEMS device to measure mechanical stiffness of single cells in aqueous media

    Science.gov (United States)

    Warnat, S.; King, H.; Forbrigger, C.; Hubbard, T.

    2015-02-01

    A method of experimentally determining the mechanical stiffness of single cells by using differential displacement measurements in a two stage spring system is presented. The spring system consists of a known MEMS reference spring and an unknown cellular stiffness: the ratio of displacements is related to the ratio of stiffness. A polyMUMPs implementation for aqueous media is presented and displacement measurements made from optical microphotographs using a FFT based displacement method with a repeatability of ~20 nm. The approach was first validated on a MEMS two stage spring system of known stiffness. The measured stiffness ratios of control structures (i) MEMS spring systems and (ii) polystyrene microspheres were found to agree with theoretical values. Mechanical tests were then performed on Saccharomyces cerevisiae (Baker’s yeast) in aqueous media. Cells were placed (using a micropipette) inside MEMS measuring structures and compressed between two jaws using an electrostatic actuator and displacements measured. Tested cells showed stiffness values between 5.4 and 8.4 N m-1 with an uncertainty of 11%. In addition, non-viable cells were tested by exposing viable cells to methanol. The resultant mean cell stiffness dropped by factor of 3 × and an explicit discrimination between viable and non-viable cells based on mechanical stiffness was seen.

  18. Simultaneous single-molecule measurements of phage T7 replisome composition and function reveal the mechanism of polymerase exchange

    NARCIS (Netherlands)

    Loparo, Joseph J.; Kulczyk, Arkadiusz W.; Richardson, Charles C.; Oijen, Antoine M. van

    2011-01-01

    A complete understanding of the molecular mechanisms underlying the functioning of large, multiprotein complexes requires experimental tools capable of simultaneously visualizing molecular architecture and enzymatic activity in real time. We developed a novel single-molecule assay that combines the

  19. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures

    OpenAIRE

    Shim, Hye Won; Yang, Byoung-Eun

    2015-01-01

    PURPOSE To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos? implants. MATERIALS AND METHODS This was a retrospective clinical study that analyzed 450 single Ankylos? implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to ag...

  20. [Study on quality standards of decoction pieces of salt Alpinia].

    Science.gov (United States)

    Li, Wenbing; Hu, Changjiang; Long, Lanyan; Huang, Qinwan; Xie, Xiuqiong

    2010-12-01

    To establish the quality criteria for decoction pieces of salt Alpinia. Decoction pieces of salt Alpinia were measured with moisture, total ash, acid-insoluble ash, water-extract and volatile oils according to the procedures recorded in the Chinese Pharmacopoeia 2010. The content of Nootkatone was determined by HPLC, and NaCl, by chloridion electrode method. We obtained results of total ash, acid-insoluble ash, water-extract and volatile oils of 10 batches of decoction pieces of salt Alpinia moisture; Meanwhile we set the HPLC and chloridion electrode method. This research established a fine quality standard for decoction pieces of salt Alpinia.

  1. The last piece of the ring

    CERN Multimedia

    2008-01-01

    In a sequel to the recent success at CMS, the last section of the LHC beam vacuum system was installed in ATLAS on Monday 16 June. The place where experiment and accelerator meet, the completion of the last part of the continuous 27 km beampipe signals how near the LHC is to the circulation of its first beam. Watch the video! The last section of the LHC beampipe being installed in ATLAS.Although a seemingly simple piece of technology in comparison with the complexity of the detectors, the beampipe is a carefully designed and essential part of both the experiments and the LHC. The section of beam pipe that completed the LHC ring on Monday 16 June is about 20 metres from the centre of ATLAS, very close to where the first magnets of the LHC are located. Unlike the central ATLAS beampipe, which is made of beryllium, the final section is made of stainless steel. An aluminium cone surrounds the stainless steel tube with the super slim...

  2. A Heuristic Bioinspired for 8-Piece Puzzle

    Science.gov (United States)

    Machado, M. O.; Fabres, P. A.; Melo, J. C. L.

    2017-10-01

    This paper investigates a mathematical model inspired by nature, and presents a Meta-Heuristic that is efficient in improving the performance of an informed search, when using strategy A * using a General Search Tree as data structure. The work hypothesis suggests that the investigated meta-heuristic is optimal in nature and may be promising in minimizing the computational resources required by an objective-based agent in solving high computational complexity problems (n-part puzzle) as well as In the optimization of objective functions for local search agents. The objective of this work is to describe qualitatively the characteristics and properties of the mathematical model investigated, correlating the main concepts of the A * function with the significant variables of the metaheuristic used. The article shows that the amount of memory required to perform this search when using the metaheuristic is less than using the A * function to evaluate the nodes of a general search tree for the eight-piece puzzle. It is concluded that the meta-heuristic must be parameterized according to the chosen heuristic and the level of the tree that contains the possible solutions to the chosen problem.

  3. Structural, spectral and mechanical studies of bimetallic crystal: cadmium manganese thiocyanate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, M.; Vijaya Prasath, G.; Mahalingam, T.; Ravi, G. [Alagappa University, Department of Physics, Karaikudi (India); Bhagavannarayan, G.; Vijayan, N. [National Physical Laboratory, Materials Characterization Division, New Delhi (India)

    2012-09-15

    A nonlinear optical bimetallic thiocyanate complex crystal, cadmium manganese thiocyanate (CMTC) has been successfully synthesized. The growth of single crystals of cadmium manganese thiocyanate has been accomplished from aqueous solution using slow evaporation method. The presence of manganese and cadmium in the synthesized material was confirmed through energy dispersive spectrum (EDS) analysis. Structural analysis was carried out using powder X-ray diffractometer (PXRD) and crystalline perfection of the grown crystals was ascertained by high-resolution X-ray diffraction (HRXRD) analysis. Fourier transform infrared (FTIR) spectrum was taken to confirm the functional groups. The transmittance spectrum of the crystal in the UV-visible region has been recorded and the cutoff wavelength has been determined. The dielectric measurements for the crystals were performed for various frequencies and temperatures. The mechanical properties were evaluated by Vickers microhardness testing, which reveals hardness and stiffness constant of the crystals. (orig.)

  4. Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

    Directory of Open Access Journals (Sweden)

    Theebhan Mogana

    2016-01-01

    Full Text Available The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar rays can be reflected to a focal point and solar thermal energy can be harvested from the focal point. Data were collected for different weather conditions and performance of the solar thermal collector with a solar tracker were studied and compared with stationary solar thermal collector.

  5. A Single Polyaniline Nanofiber Field Effect Transistor and Its Gas Sensing Mechanisms

    Science.gov (United States)

    Chen, Dajing; Lei, Sheng; Chen, Yuquan

    2011-01-01

    A single polyaniline nanofiber field effect transistor (FET) gas sensor fabricated by means of electrospinning was investigated to understand its sensing mechanisms and optimize its performance. We studied the morphology, field effect characteristics and gas sensitivity of conductive nanofibers. The fibers showed Schottky and Ohmic contacts based on different electrode materials. Higher applied gate voltage contributes to an increase in gas sensitivity. The nanofiber transistor showed a 7% reversible resistance change to 1 ppm NH3 with 10 V gate voltage. The FET characteristics of the sensor when exposed to different gas concentrations indicate that adsorption of NH3 molecules reduces the carrier mobility in the polyaniline nanofiber. As such, nanofiber-based sensors could be promising for environmental and industrial applications. PMID:22163969

  6. Failure of single electron descriptions of molecular orbital collision processes. [Electron promotion mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Elston, S.B.

    1978-01-01

    Inner-shell excitation occurring in low and moderate (keV range) energy collisions between light atomic and ionic systems is frequently describable in terms of molecular promotion mechanisms, which were extensively explored both theoretically and experimentally. The bulk of such studies have concentrated on processes understandable through the use of single- and independent-electron models. Nonetheless, it is possible to find cases of inner-shell excitation in relatively simple collision systems which involve nearly simultaneous multiple-electron transitions and transitions induced by inherently two-electron interactions. Evidence for these many- and nonindependent-electron phenomena in inner-shell excitation processes and the importance of considering such effects in the interpretation of collisionally induced excitation spectra is discussed. 13 references.

  7. Mechanical confinement for tuning ferroelectric response in PMN-PT single crystal

    Science.gov (United States)

    Patel, Satyanarayan; Chauhan, Aditya; Vaish, Rahul

    2015-02-01

    Ferroelectrics form an important class of materials and are employed for a variety of applications. However, specific applications dictate the need of tailored ferroelectric response. This creates a requirement to obtain ferroelectric materials with tunable properties. Generally, chemical modifications or domain engineering are employed to this effect. This study attempts to shed light on the use of compressive pre-stresses for tuning and enhancing the ferroelectric properties. For the purpose, polarization versus electric field hysteresis data for 68Pb(Mn1/3Nb2/3)O3-32PbTiO3 (PMN-PT) single crystals were obtained as a function of uniaxial compressive stresses and operating temperatures. These data were utilized to investigate the effects of mechanical confinement for four individual case studies of electrocaloric effect, electrical energy storage, pyroelectric, and piezoelectric effect. A significant improvement was obtained for all case studies. The adiabatic temperature change was improved by ≈80% (28 MPa, 353 K); energy storage density increased by a factor of five (28 MPa, 353 K); pyroelectric figure of merits improved by an order of magnitude (21 MPa) and the piezoelectric coefficient was tailored (variable stress). The results offer promising insight into the use of directional confinement for improving application specific ferroelectric properties in PMN-PT single crystal.

  8. Quantifying cellular mechanics and adhesion in renal tubular injury using single cell force spectroscopy.

    Science.gov (United States)

    Siamantouras, Eleftherios; Hills, Claire E; Squires, Paul E; Liu, Kuo-Kang

    2016-05-01

    Tubulointerstitial fibrosis represents the major underlying pathology of diabetic nephropathy where loss of cell-to-cell adhesion is a critical step. To date, research has predominantly focussed on the loss of cell surface molecular binding events that include altered protein ligation. In the current study, atomic force microscopy single cell force spectroscopy (AFM-SCFS) was used to quantify changes in cellular stiffness and cell adhesion in TGF-β1 treated kidney cells of the human proximal tubule (HK2). AFM indentation of TGF-β1 treated HK2 cells showed a significant increase (42%) in the elastic modulus (stiffness) compared to control. Fluorescence microscopy confirmed that increased cell stiffness is accompanied by reorganization of the cytoskeleton. The corresponding changes in stiffness, due to F-actin rearrangement, affected the work of detachment by changing the separation distance between two adherent cells. Overall, our novel data quantitatively demonstrate a correlation between cellular elasticity, adhesion and early morphologic/phenotypic changes associated with tubular injury. Diabetes affects many patients worldwide. One of the long term problems is diabetic nephropathy. Here, the authors utilized atomic force microscopy single cell force spectroscopy (AFM- SCFS) to study cellular stiffness and cell adhesion after TGF1 treatment in human proximal tubule kidney cells. The findings would help further understand the overall disease mechanism in diabetic patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Role of solvent environments in single molecule conductance used insulator-modified mechanically controlled break junctions

    Science.gov (United States)

    Muthusubramanian, Nandini; Maity, Chandan; Galan Garcia, Elena; Eelkema, Rienk; Grozema, Ferdinand; van der Zant, Herre; Kavli Institute of Nanoscience Collaboration; Department of Chemical Engineering Collaboration

    We present a method for studying the effects of polar solvents on charge transport through organic/biological single molecules by developing solvent-compatible mechanically controlled break junctions of gold coated with a thin layer of aluminium oxide using plasma enhanced atomic layer deposition (ALD). The optimal oxide thickness was experimentally determined to be 15 nm deposited at ALD operating temperature of 300°C which yielded atomically sharp electrodes and reproducible single-barrier tunnelling behaviour across a wide conductance range between 1 G0 and 10-7 G0. The insulator protected MCBJ devices were found to be effective in various solvents such as deionized water, phosphate buffered saline, methanol, acetonitrile and dichlorobenzene. The yield of molecular junctions using such insulated electrodes was tested by developing a chemical protocol for synthesizing an amphipathic form of oligo-phenylene ethynylene (OPE3-PEO) with thioacetate anchoring groups. This work has further applications in studying effects of solvation, dipole orientation and other thermodynamic interactions on charge transport. Eu Marie Curie Initial Training Network (ITN). MOLECULAR-SCALE ELECTRONICS: ``MOLESCO'' Project Number 606728.

  10. Mechanisms of temporal variation in single-nephron blood flow in rats

    DEFF Research Database (Denmark)

    Yip, K P; Holstein-Rathlou, N H; Marsh, D J

    1993-01-01

    Modified laser-Doppler velocimetry was used to determine the number of different mechanisms regulating single-nephron blood flow. Two oscillations were identified in star vessel blood flow, one at 20-50 mHz and another at 100-200 mHz. Tubuloglomerular feedback (TGF) mediates the slower oscillation......, and the faster one is probably myogenic in origin. Acute hypertension increased autospectral power in the 20-50 mHz and 100-200 mHz frequency bands to 282 +/- 50 and 248 +/- 64%, respectively, of control even though mean single-nephron blood flow was autoregulated. Mean blood flow increased 24.6 +/- 6.1% when...... TGF was inhibited by intratubular perfusion with furosemide, and it decreased 42.8 +/- 3.9% when TGF was saturated by tubular perfusion with artificial tubular fluid at high rates. Autospectral power in the low-frequency band decreased 50.5 +/- 9.6% during furosemide and decreased 74.9 +/- 5.9% during...

  11. Experimental results of single screw mechanical tests: a follow-up to SAND2005-6036.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sandwook; Lee, Kenneth L.; Korellis, John S.; McFadden, Sam X.

    2006-08-01

    The work reported here was conducted to address issues raised regarding mechanical testing of attachment screws described in SAND2005-6036, as well as to increase the understanding of screw behavior through additional testing. Efforts were made to evaluate fixture modifications and address issues of interest, including: fabrication of 45{sup o} test fixtures, measurement of the frictional load from the angled fixture guide, employment of electromechanical displacement transducers, development of a single-shear test, and study the affect of thread start orientation on single-shear behavior. A286 and 302HQ, No.10-32 socket-head cap screws were tested having orientations with respect to the primary loading axis of 0{sup 0}, 45{sup o}, 60{sup o}, 75{sup o} and 90{sup o} at stroke speeds 0,001 and 10 in/sec. The frictional load resulting from the angled screw fixture guide was insignificant. Load-displacement curves of A286 screws did not show a minimum value in displacement to failure (DTF) for 60{sup o} shear tests. Tests of 302HQ screws did not produce a consistent trend in DTF with load angle. The effect of displacement rate on DTF became larger as shear angle increased for both A286 and 302HQ screws.

  12. The nesprin-cytoskeleton interface probed directly on single nuclei is a mechanically rich system.

    Science.gov (United States)

    Balikov, Daniel A; Brady, Sonia K; Ko, Ung Hyun; Shin, Jennifer H; de Pereda, Jose M; Sonnenberg, Arnoud; Sung, Hak-Joon; Lang, Matthew J

    2017-09-03

    The cytoskeleton provides structure and plays an important role in cellular function such as migration, resisting compression forces, and transport. The cytoskeleton also reacts to physical cues such as fluid shear stress or extracellular matrix remodeling by reorganizing filament associations, most commonly focal adhesions and cell-cell cadherin junctions. These mechanical stimuli can result in genome-level changes, and the physical connection of the cytoskeleton to the nucleus provides an optimal conduit for signal transduction by interfacing with nuclear envelope proteins, called nesprins, within the LINC (linker of the nucleus to the cytoskeleton) complex. Using single-molecule on single nuclei assays, we report that the interactions between the nucleus and the cytoskeleton, thought to be nesprin-cytoskeleton interactions, are highly sensitive to force magnitude and direction depending on whether cells are historically interfaced with the matrix or with cell aggregates. Application of ∼10-30 pN forces to these nesprin linkages yielded structural transitions, with a base transition size of 5-6 nm, which are speculated to be associated with partial unfoldings of the spectrin domains of the nesprins and/or structural changes of histones within the nucleus.

  13. Identifying sequential substrate binding at the single-molecule level by enzyme mechanical stabilization.

    Science.gov (United States)

    Rivas-Pardo, Jaime Andrés; Alegre-Cebollada, Jorge; Ramírez-Sarmiento, César A; Fernandez, Julio M; Guixé, Victoria

    2015-01-01

    Enzyme-substrate binding is a dynamic process intimately coupled to protein structural changes, which in turn changes the unfolding energy landscape. By the use of single-molecule force spectroscopy (SMFS), we characterize the open-to-closed conformational transition experienced by the hyperthermophilic adenine diphosphate (ADP)-dependent glucokinase from Thermococcus litoralis triggered by the sequential binding of substrates. In the absence of substrates, the mechanical unfolding of TlGK shows an intermediate 1, which is stabilized in the presence of Mg·ADP(-), the first substrate to bind to the enzyme. However, in the presence of this substrate, an additional unfolding event is observed, intermediate 1*. Finally, in the presence of both substrates, the unfolding force of intermediates 1 and 1* increases as a consequence of the domain closure. These results show that SMFS can be used as a powerful experimental tool to investigate binding mechanisms of different enzymes with more than one ligand, expanding the repertoire of protocols traditionally used in enzymology.

  14. Finite element analysis of mechanics of lateral transmission of force in single muscle fiber.

    Science.gov (United States)

    Zhang, Chi; Gao, Yingxin

    2012-07-26

    Most of the myofibers in long muscles of vertebrates terminate within fascicles without reaching either end of the tendon, thus force generated in myofibers has to be transmitted laterally through the extracellular matrix (ECM) to adjacent fibers; which is defined as the lateral transmission of force in skeletal muscles. The goal of this study was to determine the mechanisms of lateral transmission of force between the myofiber and ECM. In this study, a 2D finite element model of single muscle fiber was developed to study the effects of mechanical properties of the endomysium and the tapered ends of myofiber on lateral transmission of force. Results showed that most of the force generated is transmitted near the end of the myofiber through shear to the endomysium, and the force transmitted to the end of the model increases with increased stiffness of ECM. This study also demonstrated that the tapered angle of the myofiber ends can reduce the stress concentration near the myofiber end while laterally transmitting force efficiently. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Modification of mechanical properties of single crystal aluminum oxide by ion beam induced structural changes

    International Nuclear Information System (INIS)

    Ensinger, W.; Nowak, R.; Horino, Y.; Baba, K.

    1993-01-01

    The mechanical behaviour of ceramics is essentially determined by their surface qualities. As a surface modification technique, ion implantation provides the possibility to modify the mechanical properties of ceramics. Highly energetic ions are implanted into the near-surface region of a material and modify its composition and structure. Ions of aluminum, oxygen, nickel and tantalum were implanted into single-crystal α-aluminum oxide. Three-point bending tests showed that an increase in flexural strength of up to 30% could be obtained after implantation of aluminum and oxygen. Nickel and tantalum ion implantation increased the fracture toughness. Indentation tests with Knoop and Vickers diamonds and comparison of the lengths of the developed radial cracks showed that ion implantation leads to a reaction in cracking. The observed effects are assigned to radiation induced structural changes of the ceramic. Ion bombardment leads to radiation damage and formation of compressive stress. In case of tantalum implantation, the implanted near-surface zone becomes amorphous. These effects make the ceramic more resistant to fracture. (orig.)

  16. On the Mechanical Behavior of a New Single-Crystal Superalloy for Industrial Gas Turbine Applications

    Science.gov (United States)

    Sato, Atsushi; Moverare, Johan J.; Hasselqvist, Magnus; Reed, Roger C.

    2012-07-01

    The mechanical behavior of a new single-crystal nickel-based superalloy for industrial gas turbine (IGT) applications is studied under creep and out-of-phase (OP) thermomechanical fatigue (TMF) conditions. Neutron diffraction methods and thermodynamic modeling are used to quantify the variation of the gamma prime ( γ') strengthening phase around the γ' solvus temperature; these aid the design of primary aging heat treatments to develop either uniform or bimodal microstructures of the γ' phase. Under creep conditions in the temperature range 1023 K to 1123 K (750 °C to 850 °C), with stresses between 235 to 520 MPa, the creep performance is best with a finer and uniform γ' microstructure. On the other hand, the OP TMF performance improves when the γ' precipitate size is larger. Thus, the micromechanical degradation mechanisms occurring during creep and TMF are distinct. During TMF, localized shear banding occurs with the γ' phase penetrated by dislocations; however, during creep, the dislocation activity is restricted to the matrix phase. The factors controlling TMF resistance are rationalized.

  17. Single-molecule FRET unveils induced-fit mechanism for substrate selectivity in flap endonuclease 1

    KAUST Repository

    Rashid, Fahad

    2017-02-23

    Human flap endonuclease 1 (FEN1) and related structure-specific 5\\'nucleases precisely identify and incise aberrant DNA structures during replication, repair and recombination to avoid genomic instability. Yet, it is unclear how the 5\\'nuclease mechanisms of DNA distortion and protein ordering robustly mediate efficient and accurate substrate recognition and catalytic selectivity. Here, single-molecule sub-millisecond and millisecond analyses of FEN1 reveal a protein-DNA induced-fit mechanism that efficiently verifies substrate and suppresses off-target cleavage. FEN1 sculpts DNA with diffusion-limited kinetics to test DNA substrate. This DNA distortion mutually \\'locks\\' protein and DNA conformation and enables substrate verification with extreme precision. Strikingly, FEN1 never misses cleavage of its cognate substrate while blocking probable formation of catalytically competent interactions with noncognate substrates and fostering their pre-incision dissociation. These findings establish FEN1 has practically perfect precision and that separate control of induced-fit substrate recognition sets up the catalytic selectivity of the nuclease active site for genome stability.

  18. A structural mechanics study of single-walled carbon nanotubes generalized from atomistic simulation.

    Science.gov (United States)

    Chen, Xi; Cao, Guoxin

    2006-02-28

    A new structural mechanics model is developed to closely duplicate the atomic configuration and behaviours of single-walled carbon nanotubes (SWCNTs). The SWCNTs are effectively represented by a space frame, where primary and secondary beams are used to bridge the nearest and next-nearest carbon atoms, to mimic energies associated with bond stretching and angle variation, respectively. The elastic properties of the frame components are generalized from molecular dynamics (MD) simulation based on an accurate ab initio force field, and numerical analyses of tension, bending, and torsion are carried out on nine different SWCNTs. The space-frame model also closely duplicates the buckling behaviours of SWCNTs in torsion and bending. In addition, by repeating the same process with continuum shell and beam models, new elastic and section parameters are fitted from the MD benchmark experiments. As an application, all three models are employed to study the thermal vibration behaviours of SWCNTs, and excellent agreements with MD analyses are found. The present analysis is a systematic structural mechanics attempt to fit SWCNT properties for several basic deformation modes and applicable to a variety of SWCNTs. The continuum models and fitted parameters may be used to effectively simulate the overall deformation behaviours of SWCNTs at much larger length- and timescales than pure MD analysis.

  19. Single Vacuum Bagging and Autoclave Curing System Influence on Physical and Mechanical Properties of Phenolic Composites

    Directory of Open Access Journals (Sweden)

    M.A. Mirzapour

    2010-12-01

    Full Text Available Industrial production of thermoset composite components involves the application of a vacuum bagging and autoclave pressure to minimize void percentage, usually to less than 5%. Phenolic resin systems generate water as a reaction byproduct via condensation reactions during curing at elevated temperatures. In this paper, vacuum bagging and simple manufactured autoclave curing systems are used for manufacturing of asbestos/phenolic composites and the effects of processing conditions on manufactured composites are investigated. The traditional single-vacuum-bag process is unable to manage the volatiles effectively, resulting in inferior laminates having voids. The autoclave process cure cycle (temperature/pressure profiles for the selected composite system is designed to emit volatiles during curing reactions effectively and produce composites with low void contents and excellent mechanical properties. Laminate consolidation quality is characterized by optical photomicrography for the cross-sections and measurements of void content and mechanical properties. The void content of phenolic composites as opposed to other composites increases as pressure increases up to 3 bar and it is then decreased beyond it. A product of 124% lower void content, 13% higher density, 24% higher flexural strength and 27% higher flexural modulus can be fabricated in composites obtainedby autoclave processing.

  20. Mechanical properties of single nanostructures investigated by in-situ AFM and micro-XRD

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, Thomas; Scheler, Thomas; Magalhaes-Paniago, Rogerio; Metzger, Till Hartmut [ESRF, Grenoble (France)

    2010-07-01

    In recent years, nanostructures attracted enormous attention due to size-effects influencing the structural, optical, electrical, and mechanical properties of materials with low dimensions. Concerning the mechanical properties mainly the plastic regime was explored showing a trend that ''smaller is stronger''. In contrast, studies of the elastic behaviour of nanowires revealed contradictory results concerning the influence of size-effects on the elasticity. To investigate single nanoobjects in the elastic regime, we combined an in-situ AFM with XRD in a microfocused beam. The AFM is used to image the sample surface, to select an individual nanostructure, and to apply pressure on a chosen object. Due to the interaction between the AFM-tip and the compressed object the resonance frequency of the AFM force sensor shifts to larger values enabling us to derive the stiffness of the contact area. Simultaneous to the pressure application, XRD images around a pre-defined Bragg peak are recorded. These images allow for the determination of the elastic lattice parameter change in-situ. From the contact stiffness and the lattice parameter change, the Young modulus of an individual nanoobject is derived. Here, we present results both for SiGe islands grown by liquid-phase epitaxy on Si wafers and GaAs nanorods created by selective-area metalorganic vapor phase epitaxy on GaAs substrates.

  1. Single-step brazing process for mono-block joints and mechanical testing

    International Nuclear Information System (INIS)

    Casalegno, V.; Ferraris, M.; Salvo, M.; Rizzo, S.; Merola, M.

    2007-01-01

    Full text of publication follows: Plasma facing components act as actively cooled thermal shields to sustain thermal and particle loads during normal and transient operations in ITER (International Thermonuclear Experimental Reactor). The plasma-facing layer is referred to as 'armour', which is made of either carbon fibre reinforced carbon composite (CFC) or tungsten (W). CFC is the reference design solution for the lower part of the vertical target of the ITER divertor. The armour is joined onto an actively cooled substrate, the heat sink, made of precipitation hardened copper alloy CuCrZr through a thin pure copper interlayer to decrease, by plastic deformation, the joint interface stresses; in fact, the CFC to Cu joint is affected by the CTE mismatch between the ceramic and metallic material. A new method of joining CFC to copper and CFC/Cu to CuCrZr alloy was effectively developed for the flat-type configuration; the feasibility of this process also for mono-block geometry and the development of a procedure for testing mono-block-type mock-ups is described in this work. The mono-block configuration consists of copper alloy pipe shielded by CFC blocks. It is worth noting that in mono-block configuration, the large thermal expansion mismatch between CFC and copper alloy is more significant than for flat-tile configuration, due to curved interfaces. The joining technique foresees a single-step brazing process: the brazing of the three materials (CFC-Cu-CuCrZr) can be performed in a single heat treatment using the same Cu/Ge based braze. The composite surface was modified by solid state reaction with chromium with the purpose of increasing the wettability of CFC by the brazing alloy. The CFC substrate reacts with Cr which, forming a carbide layer, allows a large reduction of the contact angle; then, the brazing of CFC to pure copper and pure copper to CuCrZr by the same treatment is feasible. This process allows to obtain good joints using a non-active brazing

  2. 7 CFR 51.1435 - U.S. Commercial Pieces.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false U.S. Commercial Pieces. 51.1435 Section 51.1435 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... STANDARDS) United States Standards for Grades of Shelled Pecans Grades § 51.1435 U.S. Commercial Pieces. The...

  3. 75 FR 28051 - Public Workshop: Pieces of Privacy

    Science.gov (United States)

    2010-05-19

    ... DEPARTMENT OF HOMELAND SECURITY Office of the Secretary Public Workshop: Pieces of Privacy AGENCY: Privacy Office, DHS. ACTION: Notice announcing public workshop. SUMMARY: The Department of Homeland Security Privacy Office will host a public workshop, ``Pieces of Privacy.'' DATES: The workshop will be...

  4. One Piece Orbitozygomatic Approach Based on the Sphenoid Ridge Keyhole

    DEFF Research Database (Denmark)

    Spiriev, Toma; Poulsgaard, Lars; Fugleholm, Kåre

    2016-01-01

    The one-piece orbitozygomatic (OZ) approach is traditionally based on the McCarty keyhole. Here, we present the use of the sphenoid ridge keyhole and its possible advantages as a keyhole for the one-piece OZ approach. Using transillumination technique the osteology of the sphenoid ridge was exami...

  5. Sigtuna Think Piece 9 Climate Change Education Research: What It ...

    African Journals Online (AJOL)

    Sigtuna Think Piece 9 Climate Change Education Research: What It Could Be and Why It Matters. ... Southern African Journal of Environmental Education ... The purpose of this think piece is to situate climate change education research in the context of research traditions, approaches and methods that are common to the ...

  6. Single sample expression-anchored mechanisms predict survival in head and neck cancer.

    Directory of Open Access Journals (Sweden)

    Xinan Yang

    2012-01-01

    Full Text Available Gene expression signatures that are predictive of therapeutic response or prognosis are increasingly useful in clinical care; however, mechanistic (and intuitive interpretation of expression arrays remains an unmet challenge. Additionally, there is surprisingly little gene overlap among distinct clinically validated expression signatures. These "causality challenges" hinder the adoption of signatures as compared to functionally well-characterized single gene biomarkers. To increase the utility of multi-gene signatures in survival studies, we developed a novel approach to generate "personal mechanism signatures" of molecular pathways and functions from gene expression arrays. FAIME, the Functional Analysis of Individual Microarray Expression, computes mechanism scores using rank-weighted gene expression of an individual sample. By comparing head and neck squamous cell carcinoma (HNSCC samples with non-tumor control tissues, the precision and recall of deregulated FAIME-derived mechanisms of pathways and molecular functions are comparable to those produced by conventional cohort-wide methods (e.g. GSEA. The overlap of "Oncogenic FAIME Features of HNSCC" (statistically significant and differentially regulated FAIME-derived genesets representing GO functions or KEGG pathways derived from HNSCC tissue among three distinct HNSCC datasets (pathways:46%, p<0.001 is more significant than the gene overlap (genes:4%. These Oncogenic FAIME Features of HNSCC can accurately discriminate tumors from control tissues in two additional HNSCC datasets (n = 35 and 91, F-accuracy = 100% and 97%, empirical p<0.001, area under the receiver operating characteristic curves = 99% and 92%, and stratify recurrence-free survival in patients from two independent studies (p = 0.0018 and p = 0.032, log-rank. Previous approaches depending on group assignment of individual samples before selecting features or learning a classifier are limited by design to

  7. Comparison of Nd: YAG capsulotomy rate between 1-piece and 3-piece acrylic intraocular lenses: A STROBE-compliant article.

    Science.gov (United States)

    Kim, Sun Young; Chung, Young Kwon; Shin, Hye Young; Lee, Mee Yon; Lee, Young-Chun; Kim, Su-Young

    2017-07-01

    The aim of the study is to compare Nd:YAG capsulotomy rate between acrylic 1- and 3-piece intraocular lenses. Among 924 eyes of 762 patients who received cataract surgery, we selected the 303 patients (404 eyes) implanted with an SN60WF 1-piece intraocular lens (Alcon, Fort Worth, TX) or a YA-60BBR 3-piece intraocular lens (Hoya Co., Tokyo, Japan). For intraindividual comparison, we enrolled the 17 patients implanted with an SN60WF in 1 eye and a YA-60BBR in the contralateral eye. We compared Nd:YAG capsulotomy rate between acrylic 1- and 3-piece intraocular lenses 24 months after the operation. Of the 404 eyes in this study, Nd:YAG capsulotomy was performed in 20 of 268 eyes (7.5%) in the SN60WF 1-piece intraocular lens group and 24 of 136 eyes (17.6%) in the YA-60BBR 3-piece intraocular lens group; the difference was statistically significant (P = .002). Among the 17 patients (34 eyes) who were implanted with 2 different inraocular lenses, Nd:YAG capsulotomy was performed in only 2 eyes (12%) in the SN60WF group and 9 eyes (53%) in the YA-60BBR group; the difference was statistically significant (P = .020).The authors found a significantly greater incidence of Nd:YAG capsulotomy in eyes who received 3-piece lenses compared with those who received 1-piece lenses.

  8. A mini-overview of single muscle fibre mechanics: the effects of age, inactivity and exercise in animals and humans.

    Science.gov (United States)

    Jee, Hyunseok; Kim, Jong-Hee

    2017-09-05

    Many basic movements of living organisms are dependent on muscle function. Muscle function allows for the coordination and harmonious integrity of movement that is necessary for various biological processes. Gross and fine motor skills are both regulated at the micro-level (single muscle fibre level), controlled by neuronal regulation, and it is therefore important to understand muscle function at both micro- and macro-levels to understand the overall movement of living organisms. Single muscle mechanics and the cellular environment of muscles fundamentally allow for the harmonious movement of our bodies. Indeed, a clear understanding of the functionality of muscle at the micro-level is indispensable for explaining muscular function at the macro-(whole gross muscle) level. By investigating single muscle fibre mechanics, we can also learn how other factors such Ca2+ kinetics, enzyme activity and contractile proteins can contribute to muscle mechanics at the micro- and macro-levels. Further, we can also describe how aging affects the capacity of skeletal muscle cells, as well as how exercise can prevent aging-based sarcopenia and frailty. The purpose of this review is to introduce and summarise the current knowledge of single muscle fibre mechanics in light of aging and inactivity. We then describe how exercise mitigates negative muscle adaptations that occur under those circumstances. In addition, single muscle fibre mechanics in both animal and human models are discussed.

  9. Mechanical performance of cement- and screw-retained all-ceramic single crowns on dental implants.

    Science.gov (United States)

    Obermeier, Matthias; Ristow, Oliver; Erdelt, Kurt; Beuer, Florian

    2018-03-01

    This in-vitro study was performed to compare the contact wear, fracture strength and failure mode of implant-supported all-ceramic single crowns manufactured with various fabrication and fixation concepts. Fifty dental implants (Conelog Ø 4,3mm/L11mm, Camlog Biotechnologies AG) were embedded and treated with all-ceramic molar single-crowns. Three groups received hand-layered zirconia crowns (IPS e.max Ceram/ IPS e.max ZirCAD, Ivoclar Vivadent AG): CZL (cement-retained zirconia-based layered) group crowns were cemented conventionally, SZL (screw-retained zirconia-based layered) group crowns were screw-retained, MZL (modified zirconia-based layered) group crowns showed a different coping design with screw retention. The specimens of SST (screw-retained sintering-technique) and SFL (screw-retained full-contour lithium-disilicate) group were CAD/CAM (Computer-aided design/computer-aided manufacturing) fabricated in the sintering technique (IPS e.max ZirCAD/IPS e.max CAD, Ivoclar Vivadent AG) and full-contour of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent AG) respectively and screw-retained. All specimens underwent artificial aging, load until failure and a scanning electron microscopy (SEM) analysis. The received data were statistically compared (one-way ANOVA; Student-Newman-Keuls test; Mann-Whitney U-test) at a significance level of 5%. Mouth-motion fatigue testing caused two abutment fractures (SST group and SZL group) and two chipping events (CZL group). Specimens of MZL group showed statistically significant less contact wear compared to the other groups (pCAD/CAM fabricated specimens towards manually veneered components. The mode of retention did not influence the fracture resistance but the failure patterns of the specimens. CAD/CAM milled lithium-disilicate crowns seemed to be a preserving factor for dental implants. The mode of retention and veneering influences the mechanical performance of implant-supported single crowns.

  10. Application of SFM and laser scanning technology to the description of mosaics piece by piece

    Directory of Open Access Journals (Sweden)

    O. Ajioka

    2014-06-01

    Full Text Available Mosaic floors of surviving buildings in Ostia have been mainly recorded in photographs. From 2008, Japanese research group carries out a project of 3d measuring of the whole structure of ancient Roman city Ostia using laser scanners, including its landscape, city blocks, streets, buildings, wall paintings and mosaics. The laser scanner allows for a more detailed analysis and a greater potential for recording mosaics. We can record the data of mosaics, which are described piece by piece. However it is hard to acquire enough high dense point cloud and the internal camera of the laser scanner produce low quality images. We introduce a possible technology of 3D recording of mosaics with high-quality colour information; SFM. The use of this technique permits us to create 3D models from images provided from a CCD camera without heavy and large laser scanners. We applied SFM system to different three types of the mosaics laid down on the floors of "the House of the Dioscuroi", "the Insula of the Muse" and "the House of Jove and Ganymede", and created high resolution orthographic images. Then we examined to compare these orthographic images with that are created from the point cloud data. As a result, we confirmed that SFM system has sufficient practical utility for the mosaic research. And we present how much of density of point cloud or ground resolution are required for the documentation of mosaics accurately.

  11. Application of SFM and laser scanning technology to the description of mosaics piece by piece

    Science.gov (United States)

    Ajioka, O.; Hori, Y.

    2014-06-01

    Mosaic floors of surviving buildings in Ostia have been mainly recorded in photographs. From 2008, Japanese research group carries out a project of 3d measuring of the whole structure of ancient Roman city Ostia using laser scanners, including its landscape, city blocks, streets, buildings, wall paintings and mosaics. The laser scanner allows for a more detailed analysis and a greater potential for recording mosaics. We can record the data of mosaics, which are described piece by piece. However it is hard to acquire enough high dense point cloud and the internal camera of the laser scanner produce low quality images. We introduce a possible technology of 3D recording of mosaics with high-quality colour information; SFM. The use of this technique permits us to create 3D models from images provided from a CCD camera without heavy and large laser scanners. We applied SFM system to different three types of the mosaics laid down on the floors of "the House of the Dioscuroi", "the Insula of the Muse" and "the House of Jove and Ganymede", and created high resolution orthographic images. Then we examined to compare these orthographic images with that are created from the point cloud data. As a result, we confirmed that SFM system has sufficient practical utility for the mosaic research. And we present how much of density of point cloud or ground resolution are required for the documentation of mosaics accurately.

  12. Single-molecule exploration of photoprotective mechanisms in light-harvesting complexes

    Science.gov (United States)

    Yang, Hsiang-Yu; Schlau-Cohen, Gabriela S.; Gwizdala, Michal; Krüger, Tjaart; Xu, Pengqi; Croce, Roberta; van Grondelle, Rienk; Moerner, W. E.

    2015-03-01

    Plants harvest sunlight by converting light energy to electron flow through the primary events in photosynthesis. One important question is how the light harvesting machinery adapts to fluctuating sunlight intensity. As a result of various regulatory processes, efficient light harvesting and photoprotection are balanced. Some of the biological steps in the photoprotective processes have been extensively studied and physiological regulatory factors have been identified. For example, the effect of lumen pH in changing carotenoid composition has been explored. However, the importance of photophysical dynamics in the initial light-harvesting steps and its relation to photoprotection remain poorly understood. Conformational and excited-state dynamics of multi-chromophore pigment-protein complexes are often difficult to study and limited information can be extracted from ensemble-averaged measurements. To address the problem, we use the Anti-Brownian ELectrokinetic (ABEL) trap to investigate the fluorescence from individual copies of light-harvesting complex II (LHCII), the primary antenna protein in higher plants, in a solution-phase environment. Perturbative surface immobilization or encapsulation schemes are avoided, and therefore the intrinsic dynamics and heterogeneity in the fluorescence of individual proteins are revealed. We perform simultaneous measurements of fluorescence intensity (brightness), excited-state lifetime, and emission spectrum of single trapped proteins. By analyzing the correlated changes between these observables, we identify forms of LHCII with different fluorescence intensities and excited-state lifetimes. The distinct forms may be associated with different energy dissipation mechanisms in the energy transfer chain. Changes of relative populations in response to pH and carotenoid composition are observed, which may extend our understanding of the molecular mechanisms of photoprotection.

  13. Rehabilitations with immediate loading of one-piece implants stabilized with intraoral welding.

    Science.gov (United States)

    Pasqualini, M E; Lauritano, D; Rossi, F; Dal Carlo, L; Shulman, M; Meynardi, F; Colombo, D; Manenti, P; Comola, G; Zampetti, P

    2018-01-01

    The authors present an implant prosthesis procedure that uses screws on one-piece implants connected with a titanium pin at their abutment level and one supporter titanium bar in order to guarantee immediate stabilization. These can be implanted and fitted with customized temporary crowns in a single surgical procedure, restoring function and aesthetics and consenting recovery of the bone deficit with reduced healing times and limited patient discomfort. One-piece wide-diameter titanium screw implants with thread measurements of 2.1 and 2.6 mm (smaller diameter) up to diameter of 4.5 mm with one abutment of 2.0 and 2.5 mm respectively, were positioned and splinted by intraoral welding. One-piece titanium implants were used together with a pin (needle) titanium implant as supporting structure to achieve deep stabilization. The Scialom-like pin has a diameter of 1.2 mm and it is long enough to reach deep cortical bone that is “bicorticalism”. The One-piece implant is tightly connected to the needle implant by means of Mondani intra-oral welding technique. In severely atrophic anterior maxilla, the use of this method allows the immediate loading of a fixed resin prosthesis soon after surgery. These implants yielded satisfactory functional and aesthetic outcome in bone-deficient upper anterior sectors, without invasive regenerative procedures. The low invasiveness of this approach also consents rapid healing, reduced biological burden and greater patient benefit.

  14. Creep rupture of mild steel compact tension test pieces

    International Nuclear Information System (INIS)

    Priddle, E.K.

    1978-10-01

    Creep rupture lives have been determined for compact tension and unnotched tensile test pieces of mild steel at 450 0 C. Three sizes of compact tension specimens were used in which the ratios of reference stress to elastic stress intensity factor were 2.76, 4.78 and 6.6 (msup(-1/2)). The analysis of results in terms of either initial reference stress or stress intensity was unable to reduce the data to a single failure curve. An empirical correlation was found between rupture time and a reference stress/crack length combination where t = 2.46 x 10 20 sub(σref) sup(-8.96) asup(-1.56) (units hours, MPa and metres). This equation has no valid application to materials or specimens other than those from which it was derived. Reported data for 1/2Cr Mo V and 2 1/4Cr Mo steels at 565 0 C were also correlated by this approach. (author)

  15. Three mechanisms model of shale gas in real state transport through a single nanopore

    Science.gov (United States)

    Li, Dongdong; Zhang, Yanyu; Sun, Xiaofei; Li, Peng; Zhao, Fengkai

    2018-02-01

    At present, the apparent permeability models of shale gas consider only the viscous flow and Knudsen diffusion of free gas, but do not take into account the influence of surface diffusion. Moreover, it is assumed that shale gas is in ideal state. In this paper, shale gas is assumed in real state, a new apparent permeability model for shale gas transport through a single nanopore is developed that captures many important migration mechanisms, such as viscous flow and Knudsen diffusion of free gas, surface diffusion of adsorbed gas. According to experimental data, the accuracy of apparent permeability model was verified. What’s more, the effects of pressure and pore radius on apparent permeability, and the effects on the permeability fraction of viscous flow, Knudsen diffusion and surface diffusion were analysed, separately. Finally, the results indicate that the error of the developed model in this paper was 3.02%, which is less than the existing models. Pressure and pore radius seriously affect the apparent permeability of shale gas. When the pore radius is small or pressure is low, the surface diffusion cannot be ignored. When the pressure and the pore radius is big, the viscous flow occupies the main position.

  16. Microstructures and mechanical properties of β-NiAlHf coated single crystal superalloy

    International Nuclear Information System (INIS)

    Gong, Xueyuan; Yang, Yonghong; Ma, Yue; Peng, Hui; Guo, Hongbo

    2016-01-01

    A β-NiAlHf coating was deposited by electron beam physical vapor deposition (EB-PVD) onto single crystal (SC) superalloy substrate. The microstructure evolution of the NiAlHf coating after annealing at 1100 °C was investigated and the mechanical properties of the coated substrate were also concerned. The crack initiation and propagation behavior of the coated substrate during three-point bending was studied. An interdiffusion zone (IDZ) was formed between the coating and substrate and the hardness of the precipitates in the IDZ layer was relatively higher than that of the coating and the substrate. The annealed specimen during bending revealed different crack initiation and propagation behavior from the uncoated specimen. Cracks were initiated at the carbides in the uncoated alloy. For the coated specimen after 10 h annealing, cracks were initiated mostly in the IDZ layer, due to the presence of μ-TCP phases. For the coated specimen after 50 h annealing, cracks were generated at the top of triangle-shaped γ′-Ni 3 Al phases where stress concentration occurred, which finally propagated into the substrate, leading to the reduction of the alloy in strength.

  17. Tribology. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts.

    Science.gov (United States)

    Gosvami, N N; Bares, J A; Mangolini, F; Konicek, A R; Yablon, D G; Carpick, R W

    2015-04-03

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation. Copyright © 2015, American Association for the Advancement of Science.

  18. Mechanical properties of ANTRIX balloon film and fabrication of single cap large volume balloons

    Science.gov (United States)

    Suneel Kumar, B.; Sreenivasan, S.; Subba Rao, J. V.; Manchanda, R. K.

    2008-11-01

    The zero pressure plastic balloons used for high altitude studies are generally made from polyethylene material. Tensile properties of the thin film polymer are the key parameters for material selection due to extremely low temperature of -90 °C encountered by the balloons in the tropopause region during the ascent at equatorial latitudes. The physical and structural properties of the material determine the uniformity of the stress distribution over the entire shell. Load stresses from the suspended load propagate via load tapes heat sealed along with the gore seals as per the balloon design. A balance between this heat seal strength and the film strength is a desirable property of the basic resin in terms of the bubble strength, gauge uniformity, and long-term storage properties. In addition, the design of the top shell of the balloon and its stress distribution play an important role since only a fraction of the balloon is deployed during the filling operation and the ascent. In this paper we describe the mechanical properties of the 'ANTRIX' film developed by us and the optimized design of single cap balloons, which have been successfully used in our experiments over the past 5 years.

  19. Strength and Failure Mechanism of Composite-Steel Adhesive Bond Single Lap Joints

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2018-01-01

    Full Text Available Carbon fiber-reinforced plastics- (CFRP- steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.

  20. Single Layer Bismuth Iodide: Computational Exploration of Structural, Electrical, Mechanical and Optical Properties

    Science.gov (United States)

    Ma, Fengxian; Zhou, Mei; Jiao, Yalong; Gao, Guoping; Gu, Yuantong; Bilic, Ante; Chen, Zhongfang; Du, Aijun

    2015-12-01

    Layered graphitic materials exhibit new intriguing electronic structure and the search for new types of two-dimensional (2D) monolayer is of importance for the fabrication of next generation miniature electronic and optoelectronic devices. By means of density functional theory (DFT) computations, we investigated in detail the structural, electronic, mechanical and optical properties of the single-layer bismuth iodide (BiI3) nanosheet. Monolayer BiI3 is dynamically stable as confirmed by the computed phonon spectrum. The cleavage energy (Ecl) and interlayer coupling strength of bulk BiI3 are comparable to the experimental values of graphite, which indicates that the exfoliation of BiI3 is highly feasible. The obtained stress-strain curve shows that the BiI3 nanosheet is a brittle material with a breaking strain of 13%. The BiI3 monolayer has an indirect band gap of 1.57 eV with spin orbit coupling (SOC), indicating its potential application for solar cells. Furthermore, the band gap of BiI3 monolayer can be modulated by biaxial strain. Most interestingly, interfacing electrically active graphene with monolayer BiI3 nanosheet leads to enhanced light absorption compared to that in pure monolayer BiI3 nanosheet, highlighting its great potential applications in photonics and photovoltaic solar cells.

  1. Assessment of continuum mechanics models in predicting buckling strains of single-walled carbon nanotubes.

    Science.gov (United States)

    Zhang, Y Y; Wang, C M; Duan, W H; Xiang, Y; Zong, Z

    2009-09-30

    This paper presents an assessment of continuum mechanics (beam and cylindrical shell) models in the prediction of critical buckling strains of axially loaded single-walled carbon nanotubes (SWCNTs). Molecular dynamics (MD) simulation results for SWCNTs with various aspect (length-to-diameter) ratios and diameters will be used as the reference solutions for this assessment exercise. From MD simulations, two distinct buckling modes are observed, i.e. the shell-type buckling mode, when the aspect ratios are small, and the beam-type mode, when the aspect ratios are large. For moderate aspect ratios, the SWCNTs buckle in a mixed beam-shell mode. Therefore one chooses either the beam or the shell model depending on the aspect ratio of the carbon nanotubes (CNTs). It will be shown herein that for SWCNTs with long aspect ratios, the local Euler beam results are comparable to MD simulation results carried out at room temperature. However, when the SWCNTs have moderate aspect ratios, it is necessary to use the more refined nonlocal beam theory or the Timoshenko beam model for a better prediction of the critical strain. For short SWCNTs with large diameters, the nonlocal shell model with the appropriate small length scale parameter can provide critical strains that are in good agreement with MD results. However, for short SWCNTs with small diameters, more work has to be done to refine the nonlocal cylindrical shell model for better prediction of critical strains.

  2. Altered cell mechanics from the inside: dispersed single wall carbon nanotubes integrate with and restructure actin.

    Science.gov (United States)

    Holt, Brian D; Shams, Hengameh; Horst, Travis A; Basu, Saurav; Rape, Andrew D; Wang, Yu-Li; Rohde, Gustavo K; Mofrad, Mohammad R K; Islam, Mohammad F; Dahl, Kris Noel

    2012-05-23

    With a range of desirable mechanical and optical properties, single wall carbon nanotubes (SWCNTs) are a promising material for nanobiotechnologies. SWCNTs also have potential as biomaterials for modulation of cellular structures. Previously, we showed that highly purified, dispersed SWCNTs grossly alter F-actin inside cells. F-actin plays critical roles in the maintenance of cell structure, force transduction, transport and cytokinesis. Thus, quantification of SWCNT-actin interactions ranging from molecular, sub-cellular and cellular levels with both structure and function is critical for developing SWCNT-based biotechnologies. Further, this interaction can be exploited, using SWCNTs as a unique actin-altering material. Here, we utilized molecular dynamics simulations to explore the interactions of SWCNTs with actin filaments. Fluorescence lifetime imaging microscopy confirmed that SWCNTs were located within ~5 nm of F-actin in cells but did not interact with G-actin. SWCNTs did not alter myosin II sub-cellular localization, and SWCNT treatment in cells led to significantly shorter actin filaments. Functionally, cells with internalized SWCNTs had greatly reduced cell traction force. Combined, these results demonstrate direct, specific SWCNT alteration of F-actin structures which can be exploited for SWCNT-based biotechnologies and utilized as a new method to probe fundamental actin-related cellular processes and biophysics.

  3. Altered Cell Mechanics from the Inside: Dispersed Single Wall Carbon Nanotubes Integrate with and Restructure Actin

    Directory of Open Access Journals (Sweden)

    Mohammad F. Islam

    2012-05-01

    Full Text Available With a range of desirable mechanical and optical properties, single wall carbon nanotubes (SWCNTs are a promising material for nanobiotechnologies. SWCNTs also have potential as biomaterials for modulation of cellular structures. Previously, we showed that highly purified, dispersed SWCNTs grossly alter F-actin inside cells. F-actin plays critical roles in the maintenance of cell structure, force transduction, transport and cytokinesis. Thus, quantification of SWCNT-actin interactions ranging from molecular, sub-cellular and cellular levels with both structure and function is critical for developing SWCNT-based biotechnologies. Further, this interaction can be exploited, using SWCNTs as a unique actin-altering material. Here, we utilized molecular dynamics simulations to explore the interactions of SWCNTs with actin filaments. Fluorescence lifetime imaging microscopy confirmed that SWCNTs were located within ~5 nm of F-actin in cells but did not interact with G-actin. SWCNTs did not alter myosin II sub-cellular localization, and SWCNT treatment in cells led to significantly shorter actin filaments. Functionally, cells with internalized SWCNTs had greatly reduced cell traction force. Combined, these results demonstrate direct, specific SWCNT alteration of F-actin structures which can be exploited for SWCNT-based biotechnologies and utilized as a new method to probe fundamental actin-related cellular processes and biophysics.

  4. RETAINED STONE PIECE IN ANTERIOR CHAMBER

    Directory of Open Access Journals (Sweden)

    ZvornicaninJasmin, Nadarevic-VodencarevicAmra

    2015-04-01

    Full Text Available ABSTRACT We read with interest the article by Surekha et al. regarding the retained stone piece in anterior chamber. Similar to the results of previous studies, the authors found that delayed intraocular foreign body (IOFB management can result in good visual outcome without an apparent increased risk of endophthalmitis or other deleterious side effects. However, the authors failed to explain the exact reason for the diminution of vision in patients left eye. It is unclear what the uncorrected visual acuity was and what kind of correction was used, more precisely type and amount of cylinder, given the presence of the corneal opacity. Since the size of the IOFB is approximately 4x4x1mm, significant irido-corneal angle changes resulting in intraocular pressure raise and optic nerve head damage can be expected. Traumatic glaucoma following open globe injury can occur in 2.7 to 19% of cases, with several risk factors associated with glaucoma development (advanced age, poor visual acuity at presentation,perforating rather than penetrating ocular injury,lens injury, presence of vitreous hemorrhage and presence of an IOFB. Earlier reportsof latetraumaticoptic neuropathy onset, even after several years, indicate that this possibility cannot be completely ruled out too. Therefore, repeated intraocular pressure measurements, gonioscopy, pupillary reaction assessment, together with through posterior segment examination including visual field and optical coherence tomography examinations can be useful in determining the possible optic nerve damage as one of the possible reasons for visual acuity reduction. The authors did not suggest any operative treatment at this time. However, it should bear in mind that the inert anterior chamber IOFB could be a risk factor for non-infectious endophthalmitis development even after many years. Also, long term retained anterior chamber foreign body leads to permanent endothelial cell loss and can even result in a corneal

  5. Studies of single walled carbon nanotubes for biomedical, mechanical and electrical applications using atomic force microscopy

    Science.gov (United States)

    Lahiji, Roya Roientan

    The promise of carbon nanotubes to provide high-strength composites implies that carbon nanotubes might find widespread use throughout the world, implying that humans everywhere will be exposed to carbon nanotube-containing materials. In order to study what effects if any carbon nanotubes might have on the function of living cells, we have studied the association of single stranded DNA (ssDNA) with single wall carbon nanotubes (SWCNTs) as a first step toward understanding the interaction of SWCNTs with living matter. Studies have been performed on both as-received and chemically oxidized SWCNTs to better understand the preferential association of ssDNA with SWCNTs. Samples of T30 ssDNA:SWCNT were examined under ambient conditions using non-contact Atomic Force Microscopy (AFM)) techniques. AFM images of well-dispersed, as-received SWCNTs revealed isolated features on the SWCNT that are 1.4 to 2.8 nm higher than the bare SWCNT itself. X-ray Photoemission Spectroscopy (XPS) confirmed these features to be T30 ssDNA in nature. Chemically oxidizing SWCNTs before dispersion by sonication is found to be an effective way to increase the number of T30 ssDNA features. A series of experiments showed that free radical scavengers such as ascorbic acid and trolox can effectively prevent the conjugation of ssDNA to SWCNTs, suggesting a significant role of free radicals in this association. Also hybridization of the complimentary ssDNA sequences showed the covalent nature of this association. These results are important to understanding the precise mechanism of ssDNA:SWCNT association and provide valuable information for future use in electronics, biosensors and as a possible drug carrier into individual cells. If SWCNTs are used in biosensor or circuit design applications then it is important to note how much energy can be stored in a SWCNT based on its shape and configuration before a permanent damage is introduced to it. Therefore a study has been done on bending SWCNTs into

  6. The Antiviral Mechanism of an Influenza A Virus Nucleoprotein-Specific Single-Domain Antibody Fragment

    Energy Technology Data Exchange (ETDEWEB)

    Hanke, Leo; Knockenhauer, Kevin E.; Brewer, R. Camille; van Diest, Eline; Schmidt, Florian I.; Schwartz, Thomas U.; Ploegh, Hidde L. (Whitehead); (MIT)

    2016-12-13

    Alpaca-derived single-domain antibody fragments (VHHs) that target the influenza A virus nucleoprotein (NP) can protect cells from infection when expressed in the cytosol. We found that one such VHH, αNP-VHH1, exhibits antiviral activity similar to that of Mx proteins by blocking nuclear import of incoming viral ribonucleoproteins (vRNPs) and viral transcription and replication in the nucleus. We determined a 3.2-Å crystal structure of αNP-VHH1 in complex with influenza A virus NP. The VHH binds to a nonconserved region on the body domain of NP, which has been associated with binding to host factors and serves as a determinant of host range. Several of the NP/VHH interface residues determine sensitivity of NP to antiviral Mx GTPases. The structure of the NP/αNP-VHH1 complex affords a plausible explanation for the inhibitory properties of the VHH and suggests a rationale for the antiviral properties of Mx proteins. Such knowledge can be leveraged for much-needed novel antiviral strategies.

    IMPORTANCEInfluenza virus strains can rapidly escape from protection afforded by seasonal vaccines or acquire resistance to available drugs. Additional ways to interfere with the virus life cycle are therefore urgently needed. The influenza virus nucleoprotein is one promising target for antiviral interventions. We have previously isolated alpaca-derived single-domain antibody fragments (VHHs) that protect cells from influenza virus infection if expressed intracellularly. We show here that one such VHH exhibits antiviral activities similar to those of proteins of the cellular antiviral defense (Mx proteins). We determined the three-dimensional structure of this VHH in complex with the influenza virus nucleoprotein and identified the interaction site, which overlaps regions that determine sensitivity of the virus to Mx proteins. Our data define a new vulnerability of influenza virus, help us to better understand the cellular antiviral mechanisms, and

  7. The Antiviral Mechanism of an Influenza A Virus Nucleoprotein-Specific Single-Domain Antibody Fragment.

    Science.gov (United States)

    Hanke, Leo; Knockenhauer, Kevin E; Brewer, R Camille; van Diest, Eline; Schmidt, Florian I; Schwartz, Thomas U; Ploegh, Hidde L

    2016-12-13

    Alpaca-derived single-domain antibody fragments (VHHs) that target the influenza A virus nucleoprotein (NP) can protect cells from infection when expressed in the cytosol. We found that one such VHH, αNP-VHH1, exhibits antiviral activity similar to that of Mx proteins by blocking nuclear import of incoming viral ribonucleoproteins (vRNPs) and viral transcription and replication in the nucleus. We determined a 3.2-Å crystal structure of αNP-VHH1 in complex with influenza A virus NP. The VHH binds to a nonconserved region on the body domain of NP, which has been associated with binding to host factors and serves as a determinant of host range. Several of the NP/VHH interface residues determine sensitivity of NP to antiviral Mx GTPases. The structure of the NP/αNP-VHH1 complex affords a plausible explanation for the inhibitory properties of the VHH and suggests a rationale for the antiviral properties of Mx proteins. Such knowledge can be leveraged for much-needed novel antiviral strategies. Influenza virus strains can rapidly escape from protection afforded by seasonal vaccines or acquire resistance to available drugs. Additional ways to interfere with the virus life cycle are therefore urgently needed. The influenza virus nucleoprotein is one promising target for antiviral interventions. We have previously isolated alpaca-derived single-domain antibody fragments (VHHs) that protect cells from influenza virus infection if expressed intracellularly. We show here that one such VHH exhibits antiviral activities similar to those of proteins of the cellular antiviral defense (Mx proteins). We determined the three-dimensional structure of this VHH in complex with the influenza virus nucleoprotein and identified the interaction site, which overlaps regions that determine sensitivity of the virus to Mx proteins. Our data define a new vulnerability of influenza virus, help us to better understand the cellular antiviral mechanisms, and provide a well-characterized tool to

  8. A Primer of Easy Pieces: Teaching through Typical Narrative.

    Science.gov (United States)

    Waldman, Peter

    1982-01-01

    A "Form Primer," developed for and used in an introductory architectural design course at Princeton University, is explained and illustrated. The concept holds that architecture is made up of a typology of pieces that are composed into a whole. (MSE)

  9. One-Piece Faraday Generator: A Paradoxical Experiment from 1851

    Science.gov (United States)

    Crooks, M. J.; And Others

    1978-01-01

    Describes an experiment based on Faraday's one-piece generator, where the rotating disk is replaced by a cylindrical permanent magnet. Explains the apparent paradox that an observer in an inertial frame could measure his absolute velocity. (GA)

  10. Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

    Science.gov (United States)

    Li, Long; Zhou, Xiaoxiao

    2018-03-23

    In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

  11. Development of the SAIT single-port surgical access robot--slave arm based on RCM mechanism.

    Science.gov (United States)

    Roh, Se-gon; Lee, Younbaek; Lee, Jongwon; Ha, Taesin; Sang, Taejun; Moon, Kyung-Won; Lee, Minhyong; Choi, Jung-yun

    2015-01-01

    An innovative single-port surgical robot has recently been developed by the Samsung Advanced Institute of Technology (SAIT). The robot can reach various surgical sites inside the abdominal cavity from a single incision on the body. It has two 7-DOF surgical tools, a 3-DOF endoscope, a flexible hyper-redundant 6-DOF guide tube, and a 6-DOF manipulator. This paper primarily focuses on the manipulator, called a slave arm, which is capable of setting the location of a Remote Center Motion (RCM) point. Because the surgical tools can explore the abdominal area through a small incision point when the RCM point is aligned with the incision area, the RCM mechanism is an integral part of the manipulator for single-port surgery. The mechanical feature, operational principle, control method, and the system architecture of the slave arm are introduced in this paper. In addition, manipulation experiments conducted validate its efficacy.

  12. Experimental study of micro-milling mechanism and surface quality of a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Qi; Gong, Yadong; Zhou, Yun Guang; Wen, Xue Long [School of Mechanical Engineering and Automation, Northeastern University, Shenyang (China)

    2017-01-15

    Micro-milling is widely used as a method for machining of micro-parts with high precision and efficiency. Taking the nickel-based single-crystal superalloy DD98 as the research object, the crystal characteristics of single-crystal materials were analysed, and the removal mechanism of single-crystal micro-milled parts was described. Based on molecular dynamics, a simulation model for nickel-based single-crystal superalloy DD98 micro-milling was established. Based on the response surface method of central composite design, the influences of spindle speed, feed rate, and milling depth on the surface roughness were examined, and a second-order regression model of the DD98 surface roughness was established. Using analysis of variance and the residuals of the model, a significant influence on surface roughness was found in the following order from large to small: Feed rate, spindle speed, and milling depth. Comparisons were conducted between the micro-milling experimental values and the predicted model values for different process parameters. The results show that the model fit is relatively high, and the adaptability is good. Scanning electron microscopy analysis of the micro-milling surfaces was performed to verify the slip and the removal mechanism of single-crystal materials. These results offer a theoretical reference and experimental basis for micro-milling of single-crystal materials.

  13. Single particle tracking-based reaction progress kinetic analysis reveals a series of molecular mechanisms of cetuximab-induced EGFR processes in a single living cell.

    Science.gov (United States)

    Kim, Do-Hyeon; Kim, Dong-Kyun; Zhou, Kai; Park, Soyeon; Kwon, Yonghoon; Jeong, Min Gyu; Lee, Nam Ki; Ryu, Sung Ho

    2017-07-01

    Cellular processes occur through the orchestration of multi-step molecular reactions. Reaction progress kinetic analysis (RPKA) can provide the mechanistic details to elucidate the multi-step molecular reactions. However, current tools have limited ability to simultaneously monitor dynamic variations in multiple complex states at the single molecule level to apply RPKA in living cells. In this research, a single particle tracking-based reaction progress kinetic analysis (sptRPKA) was developed to simultaneously determine the kinetics of multiple states of protein complexes in the membrane of a single living cell. The subpopulation ratios of different states were quantitatively (and statistically) reliably extracted from the diffusion coefficient distribution rapidly acquired by single particle tracking at constant and high density over a long period of time using super-resolution microscopy. Using sptRPKA, a series of molecular mechanisms of epidermal growth factor receptor (EGFR) cellular processing induced by cetuximab were investigated. By comprehensively measuring the rate constants and cooperativity of the molecular reactions involving four EGFR complex states, a previously unknown intermediate state was identified that represents the rate limiting step responsible for the selectivity of cetuximab-induced EGFR endocytosis to cancer cells.

  14. Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence

    Science.gov (United States)

    Ge, Wenchao; Bhattacharya, M.

    2016-10-01

    Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.

  15. Direct correlation of single-molecule properties with bulk mechanical performance for the biomimetic design of polymers.

    Science.gov (United States)

    Chung, Jaeyoon; Kushner, Aaron M; Weisman, Adam C; Guan, Zhibin

    2014-11-01

    For rational design of advanced polymeric materials, it is critical to establish a clear mechanistic link between the molecular structure of a polymer and the emergent bulk mechanical properties. Despite progress towards this goal, it remains a major challenge to directly correlate the bulk mechanical performance to the nanomechanical properties of individual constituent macromolecules. Here, we show a direct correlation between the single-molecule nanomechanical properties of a biomimetic modular polymer and the mechanical characteristics of the resulting bulk material. The multi-cyclic single-molecule force spectroscopy (SMFS) data enabled quantitative derivation of the asymmetric potential energy profile of individual module rupture and re-folding, in which a steep dissociative pathway accounted for the high plateau modulus, while a shallow associative well explained the energy-dissipative hysteresis and dynamic, adaptive recovery. These results demonstrate the potential for SMFS to serve as a guide for future rational design of advanced multifunctional materials.

  16. Discharge mechanisms and electrochemical impedance spectroscopy measurements of single negative and positive lead-acid battery plates

    Energy Technology Data Exchange (ETDEWEB)

    D' Alkaine, C.V. [Group of Electrochemistry and Polymers, Chemistry Department, Federal University of Sao Carlos, 13560-905 Sao Carlos, SP (Brazil); Mengarda, P.; Impinnisi, P.R. [Battery Laboratory, Institute of Technology for Development - LACTEC, Curitiba, PR (Brazil)

    2009-06-01

    This study interpreted open circuit impedance measurements of single negative and positive lead-acid battery plates, which were at different discharge levels and arranged in a four-electrode cell. This was performed in the framework of a proposed general model of charge/discharge reactions, morphological models of active materials, and based on interpretation of the characteristics of single negative and positive plates as measured by electrochemical impedance spectroscopy (EIS). This study shows that the proposed reaction models, morphological characteristics and EIS attributions are compatible with the obtained EIS data. The analysis indicates that negative and positive plate reaction mechanisms cannot be those proposed by the dissolution-precipitation mechanism alone. Rather, the reactions seem to obey the various mechanisms and morphologic ideas proposed in the present paper. It is shown that variations in the resistivity and dielectric constants of discharged films need to be studied in greater detail than film thicknesses to gain a better understanding of the processes. (author)

  17. Optimization of the transition piece applying genetic algorithms

    International Nuclear Information System (INIS)

    Gallegos Munoz, A.; Ayala-Ramirez, V.; Alfaro-Ayala, J.A.; Toledo Acosta, B.M.

    2011-01-01

    The geometric optimization of the gas turbine transition piece, applying the Computational Fluid Dynamics (CFD) and Genetic Algorithms (GA), to obtain a uniform temperature and velocity distribution in the center of the outlet section, is presented. The study is carried out considering different dimensions of the transition piece which were defined by the genetic algorithm analysis. In each case, the temperature and velocity contours of the combustion gases are examined along the transition piece and outlet section, comparing the radial and circumferential velocity and temperature profiles. In this study, it is important to know the temperature and velocity profiles at the outlet of the transition piece, because they have impact on the vanes and blades of the first stage of the gas turbine. The study considers a steady state three-dimensional model, using FLUENT version 6.3.26 and a code of genetic algorithms where the geometric parameters were analyzed. To obtain the results, a structured grid about 5.1 million cells with second-order upwind scheme and coupled solver was applied. The results show the effect of the geometry of the transition piece in the velocity and temperature profiles at the outlet area, where the change of the cross sectional area influences the contours. A smooth change in the cross sectional section allows a uniform temperature and velocity distribution at the outlet section of the transition piece. The peak value of the temperature is decreased about 5.5% (11.4 K) in the radial direction whereas the velocity is decreased 3.62% (4.27 m/s). The peak value of the temperature in the circumferential direction is decreased about 3.33% (45.51 K) whereas velocity is decreased 3.63% (4.171 m/s). The new geometry of the transition piece leads to a diminution of the average turbine inlet temperature (TIT) of about 2.32% (28.29 K) and the average velocity of about 7.73% (4.217 m/s). - Highlights: → We apply two tools of analysis to optimize the

  18. Mechanical properties of wood

    Science.gov (United States)

    David W. Green; Jerrold E. Winandy; David E. Kretschmann

    1999-01-01

    The mechanical properties presented in this chapter were obtained from tests of small pieces of wood termed “clear” and “straight grained” because they did not contain characteristics such as knots, cross grain, checks, and splits. These test pieces did have anatomical characteristics such as growth rings that occurred in consistent patterns within each piece. Clear...

  19. Nanosprings, Another Piece of the Nanotechnology Puzzle

    Science.gov (United States)

    McIlroy, David

    2003-11-01

    Nanotechnology is being touted as the next significant advancement in science and technology. The proposed applications for nanotechnology range from biological sensors to nanorobotics, to name a few. In order to take nanotechnology from the realm of science fiction to reality we need determine what is possible, as dictated by the laws of physics, and what is not. Often times when approaching a new problem we have a tendency to over complicate the problem. Therefore, when developing nanomachines we should start simple. An excellent place to start is with toys. Toys are designed to perform complex functions using the simplest of designs. If we dictate that our toy performs a function or action then energy will be needed, as well as a means for storing energy. The simplest mechanism that satisfies these two requirements is a spring. In this presentation a summary of the efforts to develop nanosprings, springs that are on the order of tens of nanometers, will be presented.

  20. Parallel versus Off-Pathway Michaelis-Menten Mechanism for Single-Enzyme Kinetics of a Fluctuating Enzyme.

    Science.gov (United States)

    Kumar, Ashutosh; Maity, Hiranmay; Dua, Arti

    2015-07-09

    Recent fluorescence spectroscopy measurements of the turnover time distribution of single-enzyme turnover kinetics of β-galactosidase provide evidence of Michaelis-Menten kinetics at low substrate concentration. However, at high substrate concentrations, the dimensionless variance of the turnover time distribution shows systematic deviations from the Michaelis-Menten prediction. This difference is attributed to conformational fluctuations in both the enzyme and the enzyme-substrate complex and to the possibility of both parallel- and off-pathway kinetics. Here, we use the chemical master equation to model the kinetics of a single fluctuating enzyme that can yield a product through either parallel- or off-pathway mechanisms. An exact expression is obtained for the turnover time distribution from which the mean turnover time and randomness parameters are calculated. The parallel- and off-pathway mechanisms yield strikingly different dependences of the mean turnover time and the randomness parameter on the substrate concentration. In the parallel mechanism, the distinct contributions of enzyme and enzyme-substrate fluctuations are clearly discerned from the variation of the randomness parameter with substrate concentration. From these general results, we conclude that an off-pathway mechanism, with substantial enzyme-substrate fluctuations, is needed to rationalize the experimental findings of single-enzyme turnover kinetics of β-galactosidase.

  1. Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zelada, Griselda I. [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Lambri, Osvaldo Agustin [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario - CONICET, Member of the CONICET& #x27; s Research Staff, Avda. Pellegrini 250, 2000 Rosario (Argentina); Bozzano, Patricia B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, 1650 San Martin (Argentina); Garcia, Jose Angel [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2012-10-15

    Mechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. The effects of alloy purity on the mechanical behavior of soft oriented NiAl single crystals

    Science.gov (United States)

    Weaver, M. L.; Kaufman, M. J.; Noebe, R. D.

    1993-01-01

    Preliminary results of the effects of alloy purity on the mechanical properties of NiAl single crystals are presented. Two stoichiometric NiAl single crystals with different impurity contents were studied. It is concluded that reductions in the interstitial and substitutional levels cause reduced yield strengths in NiAl. Heat treatment also results in reduced yield and flow stresses in both CP-NiAl and Hp-NiAl which are considered to be due to a reduction in the concentration of thermal vacancies due to vacancy coalescence during heat treatment.

  3. Graphene: The Missing Piece for Cancer Diagnosis?

    Science.gov (United States)

    Cruz, Sandra M. A.; Girão, André F.; Gonçalves, Gil; Marques, Paula A. A. P.

    2016-01-01

    This paper reviews recent advances in graphene-based biosensors development in order to obtain smaller and more portable devices with better performance for earlier cancer detection. In fact, the potential of Graphene for sensitive detection and chemical/biological free-label applications results from its exceptional physicochemical properties such as high electrical and thermal conductivity, aspect-ratio, optical transparency and remarkable mechanical and chemical stability. Herein we start by providing a general overview of the types of graphene and its derivatives, briefly describing the synthesis procedure and main properties. It follows the reference to different routes to engineer the graphene surface for sensing applications with organic biomolecules and nanoparticles for the development of advanced biosensing platforms able to detect/quantify the characteristic cancer biomolecules in biological fluids or overexpressed on cancerous cells surface with elevated sensitivity, selectivity and stability. We then describe the application of graphene in optical imaging methods such as photoluminescence and Raman imaging, electrochemical sensors for enzymatic biosensing, DNA sensing, and immunosensing. The bioquantification of cancer biomarkers and cells is finally discussed, particularly electrochemical methods such as voltammetry and amperometry which are generally adopted transducing techniques for the development of graphene based sensors for biosensing due to their simplicity, high sensitivity and low-cost. To close, we discuss the major challenges that graphene based biosensors must overcome in order to reach the necessary standards for the early detection of cancer biomarkers by providing reliable information about the patient disease stage. PMID:26805845

  4. Graphene: The Missing Piece for Cancer Diagnosis?

    Directory of Open Access Journals (Sweden)

    Sandra M. A. Cruz

    2016-01-01

    Full Text Available This paper reviews recent advances in graphene-based biosensors development in order to obtain smaller and more portable devices with better performance for earlier cancer detection. In fact, the potential of Graphene for sensitive detection and chemical/biological free-label applications results from its exceptional physicochemical properties such as high electrical and thermal conductivity, aspect-ratio, optical transparency and remarkable mechanical and chemical stability. Herein we start by providing a general overview of the types of graphene and its derivatives, briefly describing the synthesis procedure and main properties. It follows the reference to different routes to engineer the graphene surface for sensing applications with organic biomolecules and nanoparticles for the development of advanced biosensing platforms able to detect/quantify the characteristic cancer biomolecules in biological fluids or overexpressed on cancerous cells surface with elevated sensitivity, selectivity and stability. We then describe the application of graphene in optical imaging methods such as photoluminescence and Raman imaging, electrochemical sensors for enzymatic biosensing, DNA sensing, and immunosensing. The bioquantification of cancer biomarkers and cells is finally discussed, particularly electrochemical methods such as voltammetry and amperometry which are generally adopted transducing techniques for the development of graphene based sensors for biosensing due to their simplicity, high sensitivity and low-cost. To close, we discuss the major challenges that graphene based biosensors must overcome in order to reach the necessary standards for the early detection of cancer biomarkers by providing reliable information about the patient disease stage.

  5. Mechanism of DNA–binding loss upon single-point mutation in p53

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    Despite our current understanding of protein−DNA recognition, the mechanism(s) underlying the loss in protein−DNA binding affinity/ ... Keywords. p53 mutants; protein-DNA interactions; molecular dynamics simulations; free energy decomposition. Abbreviations ... of the salt–bridge with Asp 281, resulting in the loss of DNA.

  6. Accuracy of Setting Work-pieces on Automatic Lines with Pallet-fixtures

    Directory of Open Access Journals (Sweden)

    L. A. Kolesnikov

    2015-01-01

    Full Text Available The accuracy of positioning surfaces to be processed on automatic lines with pallet-fixtures essentially depends on the setting error of the pallet-fixtures with work-pieces in ready-to-work position.The applied methods for calculating the setting error do not give a complete picture of the possible coordinates of the point when in the pallet is displaced in different directions.The aim of the work was to determine an accuracy of the setting work-pieces on automatic lines with pallets-fixtures, using a computational and analytical method, to improve a manufacturing precision of parts.The currently used methods to calculate the setting error do not give a complete picture of the possible coordinates of the point of the pallet displacement in different directions. The paper offers a method of equivalent mechanism to determine all the variety of options for displacements in the horizontal plane with a diverse combination of angular and plane-parallel displacements.Using a four-bar linkage, as an equivalent mechanism, allows us to define a zone of the possible positions of any point of the work-piece pallet platform, as the zone bounded by the coupler curve. In case the gaps in the nodes of the two fixtures are equal the zone of possible positions of the point in the parallel displacement of the platform is determined by the circumference and at an angular displacement by the ellipse.The obtained analytical dependences allow us to determine the error at the stage of design with the certain gaps in the fixture nodes.The above method of calculation makes it possible to define a zone of the appropriate placement of the work-piece on its platform for the specified parameters of the pallet to meet conditions for ensuring the coordinate accuracy of the processed axes of holes.

  7. Fluctuation mechanisms in superconductors nanowire single-photon counters, enabled by effective top-down manufacturing

    CERN Document Server

    Bartolf, Holger

    2016-01-01

    Holger Bartolf discusses state-of-the-art detection concepts based on superconducting nanotechnology as well as sophisticated analytical formulæ that model dissipative fluctuation-phenomena in superconducting nanowire single-photon detectors. Such knowledge is desirable for the development of advanced devices which are designed to possess an intrinsic robustness against vortex-fluctuations and it provides the perspective for honorable fundamental science in condensed matter physics. Especially the nanowire detector allows for ultra-low noise detection of signals with single-photon sensitivity and GHz repetition rates. Such devices have a huge potential for future technological impact and might enable unique applications (e.g. high rate interplanetary deep-space data links from Mars to Earth). Contents Superconducting Single-Photon Detectors Nanotechnological Manufacturing; Scale: 10 Nanometer Berezinskii-Kosterlitz Thouless (BKT) Transition, Edge-Barrier, Phase Slips Target Groups Researchers and students of...

  8. Mechanical and Electrical Properties of a Polyimide Film Significantly Enhanced by the Addition of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Meador, Michael A.

    2005-01-01

    Single-wall carbon nanotubes have been shown to possess a combination of outstanding mechanical, electrical, and thermal properties. The use of carbon nanotubes as an additive to improve the mechanical properties of polymers and/or enhance their thermal and electrical conductivity has been a topic of intense interest. Nanotube-modified polymeric materials could find a variety of applications in NASA missions including large-area antennas, solar arrays, and solar sails; radiation shielding materials for vehicles, habitats, and extravehicular activity suits; and multifunctional materials for vehicle structures and habitats. Use of these revolutionary materials could reduce vehicle weight significantly and improve vehicle performance and capabilities.

  9. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    Science.gov (United States)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

  10. A Single-Molecule View of Genome Editing Proteins: Biophysical Mechanisms for TALEs and CRISPR/Cas9.

    Science.gov (United States)

    Cuculis, Luke; Schroeder, Charles M

    2017-06-07

    Exciting new advances in genome engineering have unlocked the potential to radically alter the treatment of human disease. In this review, we discuss the application of single-molecule techniques to uncover the mechanisms behind two premier classes of genome editing proteins: transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated system (Cas). These technologies have facilitated a striking number of gene editing applications in a variety of organisms; however, we are only beginning to understand the molecular mechanisms governing the DNA editing properties of these systems. Here, we discuss the DNA search and recognition process for TALEs and Cas9 that have been revealed by recent single-molecule experiments.

  11. Different quantization mechanisms in single-electron pumps driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Utko, P.; Gloos, K.; Hansen, Jørn Bindslev

    2006-01-01

    We have studied the acoustoelectric current in single-electron pumps driven by surface acoustic waves. We have found that in certain parameter ranges two different sets of quantized steps dominate the acoustoelectric current versus gate-voltage characteristics. In some cases, both types of quanti......We have studied the acoustoelectric current in single-electron pumps driven by surface acoustic waves. We have found that in certain parameter ranges two different sets of quantized steps dominate the acoustoelectric current versus gate-voltage characteristics. In some cases, both types...

  12. A comparative study of microstructure and mechanical properties between friction stir welded single and double phase brass alloys

    Energy Technology Data Exchange (ETDEWEB)

    Heidarzadeh, A.; Saeid, T., E-mail: saeid@sut.ac.ir

    2016-01-01

    This study was done in order to compare the microstructure and mechanical properties of friction stir welded single and double phase brass alloys. The microstructure of the joints were examined using optical microscope, scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and X-ray diffraction. Furthermore, tensile test and fractography were applied to evaluate the mechanical properties of the joints. The results showed that the grain size of the stir zone in the double phase joint was smaller than that of the single phase alloy. In comparison with base metals, both of the joints contained high density of dislocations with a qualitatively similar texture. However, the dislocation density of the double phase joint was somewhat lower than that of the single phase one. Moreover, the joints had higher tensile strength, lower elongation and less ductile fracture compared to their base metals due to their finer grain size and higher dislocation density. The double phase joint had higher strength and lower elongation than single phase joint due to the effect of the second phase.

  13. Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography

    International Nuclear Information System (INIS)

    Ciccarelli, G.; Frost, D.L.

    1994-01-01

    Flash X-ray and high-speed regular photography were used to investigate the fragmentation processes during the vapor explosion of single drops of molten metal immersed in water. For relatively low ambient flow velocities ( 45 m/s), vapor bubble growth is diminished and high-speed motion of vapor within the bubble leads to an enhanced fragmentation rate. (orig.)

  14. Single molecule charge transport : From a quantum mechanical to a classical description

    NARCIS (Netherlands)

    Kocherzhenko, A.A.; Grozema, F.C.; Siebbeles, L.D.A.

    2010-01-01

    This paper explores charge transport at the single molecule level. The conductive properties of both small organic molecules and conjugated polymers (molecular wires) are considered. In particular, the reasons for the transition from fully coherent to incoherent charge transport and the approaches

  15. Quantum Sensing of Mechanical Motion with a Single InAs Quantum Dot

    Science.gov (United States)

    2017-03-01

    manipulate s the entangle hanical racker1, Mi a E. Econo el Scheibn arch Laborat e Solutions, I at the Naval ysics, Virginia es...stal waveguide the membrane h resolution ed by sending cavity with a . , resolu single photo ...ability to as enhance the this platform . . . .

  16. Single shot damage mechanism of Mo/Si multilayer optics under intense pulsed XUV-exposures

    NARCIS (Netherlands)

    Khorsand, A.R.; Sobierajski, R.; Louis, Eric; Bruijn, S.; Gleeson, A.; van de Kruijs, Robbert Wilhelmus Elisabeth; Gullikson, E.M.; Bijkerk, Frederik

    2010-01-01

    We investigated single shot damage of Mo/Si multilayer coatings exposed to the intense fs XUV radiation at the Free-electron LASer facility in Hamburg - FLASH. The interaction process was studied in situ by XUV reflectometry, time resolved optical microscopy, and “post-mortem” by

  17. Mechanical properties of mammalian single smooth muscle cells. I. A low cost large range microforce transducer.

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron)

    1990-01-01

    textabstractA transducer has been developed for measuring the minute forces generated during isometric contractions (1.0-10.0 microN) of single smooth muscle cells from the pig urinary bladder and the human uterus. In addition to its high sensitivity, resolution and stability (100 mV microN-1, and

  18. Feminist Erotica and Agency @ The Love Piece Club

    OpenAIRE

    DALES, Laura

    2008-01-01

    The Love Piece Club is a shop devoted to sex goods for women, located in Tokyo and online at www.lovepiececlub.com. As well as online shopping, the website offers regular columns, articles and photo-essays on subjects related to sexuality and women's lives. The site and shop are managed by Kitahara Minori, a writer, businesswoman and advocate for feminist erotica. This paper explores the Love Piece Club as a discursive site – its potential meanings and its significance as a feminist work in p...

  19. Exploring transduction mechanisms of protein transduction domains (PTDs) in living cells utilizing single-quantum dot tracking (SQT) technology.

    Science.gov (United States)

    Suzuki, Yasuhiro

    2012-01-01

    Specific protein domains known as protein transduction domains (PTDs) can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs), we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP) in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT), to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.

  20. Exploring Transduction Mechanisms of Protein Transduction Domains (PTDs in Living Cells Utilizing Single-Quantum Dot Tracking (SQT Technology

    Directory of Open Access Journals (Sweden)

    Yasuhiro Suzuki

    2012-01-01

    Full Text Available Specific protein domains known as protein transduction domains (PTDs can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs, we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT, to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency.

  1. Scanning electron microscopic characteristics of commercially available 1- and 3-piece intraocular lenses.

    Science.gov (United States)

    Brockmann, Tobias; Brockmann, Claudia; Nietzsche, Sandor; Bertelmann, Eckart; Strobel, Juergen; Dawczynski, Jens

    2013-12-01

    To evaluate commercially available 1- and 3-piece intraocular lenses (IOLs) with scanning electron microscopy (SEM). Department of Ophthalmology and Electron Microscopy Center, University Hospital Jena, Jena, Germany. Experimental study. Seven +23.0 diopter IOLs of different design and material and from different manufacturers were chosen for a detailed assessment. Scanning electron microscopy was used at standardized magnifications to assess typical IOL characteristics. The particular focus was the optic edge, the optic surface, the haptic–optic junction, and the haptic. All square-edged IOLs had a curvature radius of less than 10 μm, while the mean optic edge thickness ranged between 216 μm and 382 μm. A 360-degree square-edged boundary was present in all 3-piece IOLs and in a single 1-piece model. Relevant production remnants on the optic edge were observed in 1 case. Regarding the haptic, 3-piece IOLs had uniformly shaped fibers with a mean thickness of 177 μm ± 51 (SD) (range 116 to 220 μm). Chemical adhesives were used to attach the haptic in 1 case, where alterations of the IOL material were observed. In another case, the haptic fiber was press-fitted into the optic, which resulted in bulging of the optic profile. Inspection of surface characteristics showed wavelike patterns in 2 IOLs. Taking clinical relevance into account, all IOLs were of high manufacturing quality. Certain attention was paid in creating a sharp optic edge. Surface irregularities of 2 IOLs were attributed to the manufacturing technique. Methods for implementing the haptic–optic junction were diverse.

  2. Electrical trapping mechanism of single-microparticles in a pore sensor

    Directory of Open Access Journals (Sweden)

    Akihide Arima

    2016-11-01

    Full Text Available Nanopore sensing via resistive pulse technique are utilized as a potent tool to characterize physical and chemical property of single –molecules and –particles. In this article, we studied the influence of particle trajectory to the ionic conductance through a pore. We performed the optical/electrical simultaneous sensing of electrophoretic capture dynamics of single-particles at a pore using a microchannel/nanopore system. We detected ionic current drops synchronous to a fluorescently dyed particle being electrophoretically drawn and become immobilized at a pore in the optical imaging. We also identified anomalous trapping events wherein particles were captured at nanoscale pin-holes formed unintentionally in a SiN membrane that gave rise to relatively small current drops. This method is expected to be a useful platform for testing novel nanopore sensor design wherein current behaves in unpredictable manner.

  3. Investigation of Chirality Selection Mechanism of Single-Walled Carbon Nanotube

    Science.gov (United States)

    2015-07-17

    strong fibers [6, 7], membranes [8], and super - capacitor electrodes [9] have been proposed and demonstrated in a laboratory environment. However, the...Hatori, M. Yumura, and S. Iijima, “Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super ... capacitor electrodes,” Nature Mater. 5, 987 (2006). [10] Y. Li, D. Mann, M. Rolandi, W. Kim, A. Ural, S. Hung, A. Javey, J. Cao, D. Dunwei, E. Yenilmez

  4. Theoretical study of catalytic mechanism for single-site water oxidation process.

    Science.gov (United States)

    Lin, Xiangsong; Hu, Xiangqian; Concepcion, Javier J; Chen, Zuofeng; Liu, Shubin; Meyer, Thomas J; Yang, Weitao

    2012-09-25

    Water oxidation is a linchpin in solar fuels formation, and catalysis by single-site ruthenium complexes has generated significant interest in this area. Combining several theoretical tools, we have studied the entire catalytic cycle of water oxidation for a single-site catalyst starting with [Ru(II)(tpy)(bpm)(OH(2))](2+) (i.e., [Ru(II)-OH(2)](2+); tpy is 2,2':6',2''-terpyridine and bpm is 2,2'-bypyrimidine) as a representative example of a new class of single-site catalysts. The redox potentials and pK(a) calculations for the first two proton-coupled electron transfers (PCETs) from [Ru(II)-OH(2)](2+) to [Ru(IV) = O](2+) and the following electron-transfer process to [Ru(V) = O](3+) suggest that these processes can proceed readily in acidic or weakly basic conditions. The subsequent water splitting process involves two water molecules, [Ru(V) = O](3+) to generate [Ru(III)-OOH](2+), and H(3)O(+) with a low activation barrier (~10 kcal/mol). After the key O-O bond forming step in the single-site Ru catalysis, another PECT process oxidizes [Ru(III)-OOH](2+) to [Ru(IV)-OO](2+) when the pH is lower than 3.7. Two possible forms of [Ru(IV)-OO](2+), open and closed, can exist and interconvert with a low activation barrier (catalytic cycle. This understanding is helpful in the design of new catalysts for water oxidation.

  5. FEA and microstructure characterization of a one-piece Y-TZP abutment.

    Science.gov (United States)

    da Silva, Lucas Hian; Ribeiro, Sebastião; Borges, Alexandre Luís Souto; Cesar, Paulo Francisco; Tango, Rubens Nisie

    2014-11-01

    The most important drawback of dental implant/abutment assemblies is the need for a fixing screw. This study aimed to develop an esthetic one-piece Y-TZP abutment to suppress the use of the screw. Material characterization was performed using a bar-shaped specimen obtained by slip-casting to validate the method prior to prototype abutment fabrication by the same process. The mechanical behavior of the prototype abutment was verified and compared with a conventional abutment by finite element analysis (FEA). The abutment was evaluated by micro-CT analysis and its density was measured. FEA showed stress concentration at the first thread pitch during installation and in the cervical region during oblique loading for both abutments. However, stress concentration was observed at the base of the screw head and stem in the conventional abutment. The relative density for the fabricated abutment was 95.68%. Micro-CT analysis revealed the presence of elongated cracks with sharp edges over the surface and porosity in the central region. In the light of these findings, the behavior of a one-piece abutment is expected to be better than that of the conventional model. New studies should be conducted to clarify the performance and longevity of this one-piece Y-TZP abutment. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Mechanical signals in plant development: a new method for single cell studies

    Science.gov (United States)

    Lynch, T. M.; Lintilhac, P. M.

    1997-01-01

    Cell division, which is critical to plant development and morphology, requires the orchestration of hundreds of intracellular processes. In the end, however, cells must make critical decisions, based on a discrete set of mechanical signals such as stress, strain, and shear, to divide in such a way that they will survive the mechanical loads generated by turgor pressure and cell enlargement within the growing tissues. Here we report on a method whereby tobacco protoplasts swirled into a 1.5% agarose entrapment medium will survive and divide. The application of a controlled mechanical load to agarose blocks containing protoplasts orients the primary division plane of the embedded cells. Photoelastic analysis of the agarose entrapment medium can identify the lines of principal stress within the agarose, confirming the hypothesis that cells divide either parallel or perpendicular to the principal stress tensors. The coincidence between the orientation of the new division wall and the orientation of the principal stress tensors suggests that the perception of mechanical stress is a characteristic of individual plant cells. The ability of a cell to determine a shear-free orientation for a new partition wall may be related to the applied load through the deformation of the matrix material. In an isotropic matrix a uniaxial load will produce a rotationally symmetric strain field, which will define a shear-free plane. Where high stress intensities combine with the loading geometry to produce multiaxial loads there will be no axis of rotational symmetry and hence no shear free plane. This suggests that two mechanisms may be orienting the division plane, one a mechanism that works in rotationally symmetrical fields, yielding divisions perpendicular to the compressive tensor, parallel to the long axis of the cell, and one in asymmetric fields, yielding divisions parallel to the short axis of the cell and the compressive tensor.

  7. Structural, mechanical and light yield characterisation of heat treated LYSO:Ce single crystals for medical imaging applications

    CERN Document Server

    Mengucci, P; Auffray, E; Barucca, G; Cecchi, C; Chipaux, R; Cousson, A; Davì, F; Di Vara, N; Rinaldi, D; Santecchia, E

    2015-01-01

    Five single crystals of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) grown by the Czochralski method were submitted to structural characterisation by X-ray (XRD) and neutron (ND) diffraction, scanning (SEM) and transmission (TEM) electron microscopy and energy dispersive microanalysis (EDS). The Ultimate Tensile Strength (UTS), the Young Modulus (YM) and the Light Yield (LY) of the samples were also measured in order to correlate the mechanical and the optical behaviour of the crystals with the characteristics of their microstructure. Two of the samples analysed were also heat treated at 300 °C for 10 h to evidence possible variations induced by the temperature in the optical and mechanical response of the crystals. Results showed that the mean compositional variations evidenced by the structural analyses do not affect the mechanical and optical behaviour of the samples. On the contrary, the thermal treatment could induce the formation of coherent spherical particles (size 10 to 15 nm), not unifo...

  8. Mechanical Stabilization of Martensite in Cu-Ni-Al Single Crystal and Unconventional Way to Detect It

    Science.gov (United States)

    Heczko, O.; Vronka, M.; Veřtát, P.; Rameš, M.; Onderková, K.; Kopecký, V.; Krátká, P.; Ge, Y.

    2018-03-01

    The microstructures and transformation behaviour of self-accommodated and mechanically stabilized martensite of Cu69.4Ni3.4Al27.2 (at.%) single crystal were investigated by optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetometry. XRD and TEM analyses showed the presence of both 2H and 18R phases in self-accommodated martensite. The mechanical compression of martensite (≈ 100 MPa) increased markedly the transformation temperature to austenite, i.e. resulting in significant mechanical stabilization of martensite. The 18R phase disappeared after the compression. This reveals the important role of 18R phase in transformation behaviour of Cu-Ni-Al alloy. Furthermore, we demonstrate that thermo-magnetic measurement is suitable method to analyse the martensitic transformation even for diamagnetic material.

  9. The Effects of Mechanical and Thermal Stimuli on Local Field Potentials and Single Unit Activity in Parkinson's Disease Patients.

    Science.gov (United States)

    Belasen, Abigail; Youn, Youngwon; Gee, Lucy; Prusik, Julia; Lai, Brant; Ramirez-Zamora, Adolfo; Rizvi, Khizer; Yeung, Philip; Shin, Damian S; Argoff, Charles; Pilitsis, Julie G

    2016-10-01

    Chronic pain is a major, debilitating symptom of Parkinson's disease (PD). Although, deep brain stimulation (DBS) has been shown to improve pain outcomes, the mechanisms underlying this phenomenon are unclear. Microelectrode recording allows us to measure both local field potentials (LFPs) and single neuronal unit activity (SUA). In this study, we examined how single unit and LFP oscillatory activity in the basal ganglia are impacted by mechanical and thermal sensory stimuli and explored their role in pain modulation. We assessed changes in LFPs and SUAs in the subthalamic nucleus (STN), globus pallidus interna (Gpi), and globus pallidus externa (Gpe) following exposure with mechanical or thermal stimuli. Sensory thresholds were determined pre-operatively using quantitative sensory testing. Based on these data, patients were exposed to innocuous and noxious mechanical, pressure, and thermal stimuli at individualized thresholds. In the STN, LFP alpha oscillatory activity and SUA increased in response to innocuous mechanical stimuli; SUA further increased in response to noxious mechanical, noxious pressure, and noxious thermal stimuli (p thermal stimuli; SUA also increased in response to innocuous thermal stimuli (p thermal stimuli increased LFP gammaactivity; noxious pressure stimuli decreased low betaactivity; SUA increased in response to noxious thermal stimuli (p thermal stimuli alter basal ganglia LFPs and SUAs in PD. While STN SUA increases nearly uniformly to all sensory stimuli, SUA in the pallidal nuclei respond solely to thermal stimuli. Similarly, thermal stimuli yield increases in pallidal LFP activity, but not STN activity. We speculate that DBS may provide analgesia through suppression of stimuli-specific changes in basal ganglia activity, supporting a role for these nuclei in sensory and pain processing circuits. © 2016 International Neuromodulation Society.

  10. Propriedades mecânicas de peças com dimensões estruturais de Pinus spp: correlação entre resistência à tração e classificação visual Mechanical properties of structural pieces of Pinus spp: relationship between tensile strength and visual grading

    Directory of Open Access Journals (Sweden)

    Juliano Fiorelli

    2009-08-01

    Full Text Available A redução da disponibilidade de espécies de madeiras nativas e seus efeitos na economia, associada ao fortalecimento dos conceitos de preservação ambiental, criou a necessidade de desenvolvimento de alternativas viáveis para utilização racional de espécies de reflorestamento. E uma das opções é a realização de classificação visual das peças. Autores de trabalhos desenvolvidos nessa linha de pesquisa verificaram a adequação das regras de classificação visual do Southern Pine Inspection Bureau (SPIB dos EUA à madeira de Pinus do Brasil e apresentaram proposta para normalizar o processo de classificação visual dessa madeira. Nessa classificação, os aspectos com maior influência são: presença de nós, desvio de grã em relação ao eixo da peça e densidade de anéis de crescimento. Assim, esta pesquisa apresenta um estudo experimental que consistiu na classificação visual e determinação da resistência à tração de 85 peças de Pinus spp e um estudo teórico, que propôs uma equação para determinar a resistência à tração média de peças estruturais em função da classificação visual. Com este trabalho, foi possível observar a influência dos nós e dos anéis de crescimento sobre a resistência à tração das peças analisadas.The reduction in the availability the native lumber species and its effects on the economy, associated to the invigoration of the concepts of environmental preservation created the necessity of the development of viable alternatives for rational use of reforestation species. One of the options is the accomplishment of visual grading of the pieces. Research works verified the adaptation of the rules of visual grading of Southern Pine Inspection Bureau (SPIB of the USA for the Brazilian lumber Pinus, presenting a proposal to normalize the process of visual grading of this lumber. In this classification, the most important aspects are the presence of knots, the inclination of the

  11. Development of debris-resistant bottom end piece

    International Nuclear Information System (INIS)

    Sohn, Dong Seong; Lee, Jae Kyung; Hwang, Dae Hyun; Yim, Jung Sik; Song, Kee Nam; Oh, Dong Seok; Im, Hyun Tae

    1993-01-01

    Debris-related fuel failures has been identified to be one of the major causes of fuel failures recently occured in nuclear power plants. In order to reduce the possibility of debris-related fuel failures, it is necessary to prevent the debris from reaching to fuel rods. In this regard, it is important to develop Debris-Resistant Bottom End Piece. (Author)

  12. Sigtuna Think Piece 5 Climate Change within Education for ...

    African Journals Online (AJOL)

    This think piece describes a way of including climate change within education for sustainable development (ESD), with a specific ambition to illuminate the moral dimension in a locally relevant way in the teaching. A method – ethical tendency discourse analysis – for creating a locally relevant teaching content that ...

  13. Let's Measure the Dielectric Constant of a Piece of Paper!

    Science.gov (United States)

    Karlow, Edwin A.

    1991-01-01

    Described is a simple circuit with which students can observe the effect of common dielectric materials in a capacitor and measure the dielectric constant of a piece of paper. Discussed are the theory, apparatus construction, and experimental procedures for this activity. (CW)

  14. A piece of paper falling faster than free fall

    International Nuclear Information System (INIS)

    Vera, F; Rivera, R

    2011-01-01

    We report a simple experiment that clearly demonstrates a common error in the explanation of the classic experiment where a small piece of paper is put over a book and the system is let fall. This classic demonstration is used in introductory physics courses to show that after eliminating the friction force with the air, the piece of paper falls with acceleration g. To test if the paper falls behind the book in a nearly free fall motion or if it is dragged by the book, we designed a version of this experiment that includes a ball and a piece of paper over a book that is forced to fall using elastic cords. We recorded a video of our experiment using a high-speed video camera at 300 frames per second that shows that the book and the paper fall faster than the ball, which falls well behind the book with an acceleration approximately equal to g. Our experiment shows that the piece of paper is dragged behind the book and therefore the paper and book demonstration should not be used to show that all objects fall with acceleration g independently of their mass.

  15. Two-piece implants with turned versus microtextured collars.

    NARCIS (Netherlands)

    Cosyn, J.; Sabzevar, M.M.; Wilde, P.C.M. de; Rouck, T. de

    2007-01-01

    Implant companies have been promoting two-piece implants with microtextured collars in the interest of hard tissue preservation and/or soft tissue integration. However, this rationale may not be justified. Based on comparative studies currently available, it is unclear whether microroughened implant

  16. Three-piece Inflatable Penile Prosthesis: Surgical Techniques and ...

    African Journals Online (AJOL)

    Penile prosthesis surgery plays a vital role in the treatment of erectile dysfunction (ED). As far as outcome is concerned, it is one of the most rewarding procedures for both patients and surgeons. We describe our surgical technique for implantation of the three-piece inflatable penile prosthesis and point out the major surgical ...

  17. Think Piece: Re-thinking Education for Sustainable Development as ...

    African Journals Online (AJOL)

    Think Piece: Re-thinking Education for Sustainable Development as Transgressive Processes of Educational Engagement with Human Conduct, Emerging ... theorising the expansive and reflexive learning of citizens and how these processes might produce the desired change towards sustainable development (SD) in ...

  18. One-piece transparent shell improves design of helmet assembly

    Science.gov (United States)

    Jones, R. L.; Okane, J. H.

    1966-01-01

    One-piece transparent helmet shell made of polycarbonate is equipped with a helmet protection pad, a visor assembly, a communications skull cap, and an emergency oxygen supply. This design offers improvements over previous designs in weight, visual field, comfort and protection.

  19. Sigtuna Think Piece 7 Readings for Climate Change: Ecocriticism ...

    African Journals Online (AJOL)

    This think piece elaborates possible research connections between ecocriticism and climate change educational research, addressing the overarching question of what cultural responses to climate change can offer climate change education and climate change education research. It investigates literary critic Louise ...

  20. Sigtuna Think Piece 1 Climate Change Education in Africa ...

    African Journals Online (AJOL)

    Sigtuna Think Piece 1 Climate Change Education in Africa. ... Southern African Journal of Environmental Education ... Though Africa produces less than 10% of total greenhouse gas emissions, the continent was noted as one of the most vulnerable to climate change by the Intergovernmental Panel on Climate Change's ...

  1. Sigtuna Think Piece 10 Reflections on the Sigtuna Climate Change ...

    African Journals Online (AJOL)

    Sigtuna Think Piece 10 Reflections on the Sigtuna Climate Change Education Research Symposium. ... Southern African Journal of Environmental Education ... a short reflection from two Master's level students who participated in the symposium on Climate Change Education held at Sigtunastiftelsen on 28 March 2009.

  2. Mechanical properties of cocoons constructed consecutively by a single silkworm caterpillar, Bombyx mori

    Science.gov (United States)

    Huang, S. Q.; Zhao, H. P.; Feng, X. Q.; Cui, W.; Lin, Z.; Xu, M. Q.

    2008-04-01

    Most animals have the ability to adapt, to some extends and in different ways, the variation or disturbance of environment. In our experiments, we forced a silkworm caterpillar to spin two, three or four thin cocoons by taking it out from the cocoon being constructed. The mechanical properties of these cocoons were studied by static tensile tests and dynamic mechanical thermal analysis. Though external disturbances may cause the decrease in the total weight of silk spun by the silkworm, a gradual enhancement was interestingly found in the mechanical properties of these thin cocoons. Scanning electron microscopy observations of the fractured specimens of the cocoons showed that there exist several different energy dissipation mechanisms occurred simultaneously at macro-, meso-, and micro-scales, yielding a superior capacity of cocoons to adsorb the energy of possible attacks from the outside and to protect efficiently its pupa against damage. Through evolution of millions of years, therefore, the silkworm Bombyx mori seems to have gained the ability to adapt external disturbances and to redesign a new cocoon with optimized protective function when its first cocoon has been damaged for some reasons.

  3. Single Molecular Detection via Micro-Scale Polymeric Opto-Electro-Mechanical Systems

    Science.gov (United States)

    2005-06-01

    5.1.1.1.2 Mechanical Characteristics The dynamics of the bottom Y microlens scanner were characterized with a Microvision Stroboscopic Motion...Hong, "Multidimensional motion analysis of MEMS using computer microvision ," Proc. IEEE Solid-State Sensor and Actuator Workshop, 150-155 (1998

  4. Insulator-protected mechanically controlled break junctions for measuring single-molecule conductance in aqueous environments

    NARCIS (Netherlands)

    Muthusubramanian, N.; Galan, E.; Maity, C.; Eelkema, R.; Grozema, F.C.; van der Zant, H.S.J.

    2016-01-01

    We present a method to fabricate insulated gold mechanically controlled break junctions (MCBJ) by coating the metal with a thin layer of aluminum oxide using plasma enhanced atomic layer deposition. The Al2O3 thickness deposited on the MCBJ devices was varied from 2 to 15 nm

  5. Acute effects of single and multiple level thoracic manipulations on chronic mechanical neck pain: a randomized controlled trial

    Science.gov (United States)

    Puntumetakul, Rungthip; Suvarnnato, Thavatchai; Werasirirat, Phurichaya; Uthaikhup, Sureeporn; Yamauchi, Junichiro; Boucaut, Rose

    2015-01-01

    Background Thoracic spine manipulation has become a popular alternative to local cervical manipulative therapy for mechanical neck pain. This study investigated the acute effects of single-level and multiple-level thoracic manipulations on chronic mechanical neck pain (CMNP). Methods Forty-eight patients with CMNP were randomly allocated to single-level thoracic manipulation (STM) at T6–T7 or multiple-level thoracic manipulation (MTM), or to a control group (prone lying). Cervical range of motion (CROM), visual analog scale (VAS), and the Thai version of the Neck Disability Index (NDI-TH) scores were measured at baseline, and at 24-hour and at 1-week follow-up. Results At 24-hour and 1-week follow-up, neck disability and pain levels were significantly (Pneck disability, pain level at rest, and CROM between the STM and MTM groups. Conclusion These results suggest that both single-level and multiple-level thoracic manipulation improve neck disability, pain levels, and CROM at 24-hour and 1-week follow-up in patients with CMNP. PMID:25624764

  6. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution.......Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... The growth mechanisms as well as the roles of different components in the catalyst were studied in situ using environmental transmission electron microscopy and infrared spectroscopy. On the basis of the understanding of carbon nanotube growth mechanisms, an MgO-supported FeCu catalyst was prepared...

  7. Environmental effects on deformation mechanism and dislocation microstructure in fatigued copper single crystal

    International Nuclear Information System (INIS)

    Yang, J.H.; Zhang, X.P.; Mai, Y.-W.; Jia, W.P.; Ke, W.

    2005-01-01

    The deformation and dislocation microstructure of a [0 1 3] double-slip-oriented copper single crystal under a symmetric tension-compression cyclic load were characterized at room temperature in open-air and a neutral 0.5 M NaCl aqueous solution, respectively. The surface morphology of deformed specimens and the dislocation structures at saturation stage of cyclic deformation were observed using scanning electron microscopy (SEM) by the electron channeling contrast (ECC) technique and transmission electron microscopy (TEM). The results show that the saturation dislocation structures during the corrosion fatigue in the 0.5 M NaCl aqueous solution mainly consist of labyrinth, wall and vein dislocation microstructures, as well as deformation twins, which differ from the wall and vein dislocation structures in open-air environment. More importantly, here we report TEM observations that provide evidence of deformation twinning in the [0 1 3] double-slip-oriented copper single crystal during corrosion fatigue at room temperature and a very slow strain rate, which was generally only observed at sub-ambient temperature and/or high strain rate conditions

  8. Promoters Architecture-Based Mechanism for Noise-Induced Oscillations in a Single-Gene Circuit.

    Science.gov (United States)

    Guisoni, N; Monteoliva, D; Diambra, L

    2016-01-01

    It is well known that single-gene circuits with negative feedback loop can lead to oscillatory gene expression when they operate with time delay. In order to generate these oscillations many processes can contribute to properly timing such delay. Here we show that the time delay coming from the transitions between internal states of the cis-regulatory system (CRS) can drive sustained oscillations in an auto-repressive single-gene circuit operating in a small volume like a cell. We found that the cooperative binding of repressor molecules is not mandatory for a oscillatory behavior if there are enough binding sites in the CRS. These oscillations depend on an adequate balance between the CRS kinetic, and the synthesis/degradation rates of repressor molecules. This finding suggest that the multi-site CRS architecture can play a key role for oscillatory behavior of gene expression. Finally, our results can also help to synthetic biologists on the design of the promoters architecture for new genetic oscillatory circuits.

  9. Single Particle Tracking to Characterize the Mechanism of Pore Formation by Pore Forming Proteins

    OpenAIRE

    Subburaj, Yamunadevi

    2014-01-01

    Pore formation is a common natural mechanism occurring in large number of organisms where proteins are involved as toxins, effectors in immune response or apoptosis. Despite intense research, the structural and dynamic aspects of oligomerization and membrane permeabilization by pore forming proteins remains poorly understood. In this work we have aimed to provide a better understanding on dynamics, oligomerization and pore forming process of two proteins; a) Equinatoxin II, b) Bax (Bcl2 famil...

  10. Electric-field-tunable mechanical properties of relaxor ferroelectric single crystal measured by nanoindentation

    OpenAIRE

    Zhou, Hao; Pei, Yongmao; Li, Faxin; Luo, Haosu; Fang, Daining

    2014-01-01

    Electric field dependent mechanical properties of relaxor ferroelectric material Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation technique. Giant electric-field-tunable apparent elastic modulus (up to -39%), hardness (-9% to 20%) and energy dissipation (up to -13%) are reported. Based on experimental data, a characterization method of electromechanical coupled nanoindentation is proposed. In this method, an electric field tunable scaling relationship among elastic modulus, h...

  11. Twenty years' single-center experience with mechanical heart valves: a critical review of anticoagulation policy.

    Science.gov (United States)

    Van Nooten, Guido J; Caes, Frank; François, Katrien; Van Bellleghem, Yves; Bové, Thierry; Vandenplas, Guy; Taeymans, Yves

    2012-01-01

    Since January 1990, a variety of mechanical valves (St. Jude Medical, CarboMedics, ATS Medical) have been implanted routinely at the authors' institution. The study aim was to analyze, retrospectively, the 20-year clinical results of those mechanical valves, and to challenge the anticoagulation policy employed over the years. Between January 1990 and December 2008, a total of 2,108 mechanical valves was inserted into 1,887 consecutive patients (1,346 aortic, 725 mitral, 27 tricuspid, 10 pulmonary). The mean age of the patients was 63 +/- 13.2 years, and the majority (61%) were males. Preoperatively, 71% the patients were in NYHA class > or = III (average 3.01). The most frequent comorbidities included: atrial fibrillation (n = 594), coronary disease (n = 567) and diabetes (n = 398). The follow up (99% complete) totaled 13,721 patient-years (pt-yr), and ranged from 12 to 241 months (average 84 months). In-hospital mortality was 5.2% (n = 98, 14 valve-related). Of the 629 late deaths, the majority were cardiac (n = 276). Survival (Kaplan-Meier estimation) was significantly better for aortic valve patients compared to mitral or multiple valve replacement (Mantel-Cox, p valve thrombosis 0.31, thromboembolism 1.08, and bleeding 0.91. However, as repeated events occurred in several patients, the hazard function was not constant. Multivariate analysis (Cox regression model) showed age > 70 years (p or = III (p II as significant risk factors for thromboembolism, while long-acting coumadin and NYHA class > II were significant risk factors for bleeding. This 20-year experience demonstrated excellent clinical outcomes for patients with mechanical prostheses, with no valve structural failure and an acceptable incidence of adverse events. INR values between 2-2.5 for aortic valve patients, and 3-3.5 for mitral valve patients, yielded the fewest major adverse events.

  12. Experimental studies of the dynamic mechanical response of a single polymer chain

    DEFF Research Database (Denmark)

    Thormann, Esben; Evans, Drew R.; Craig, Vincent S. J.

    2006-01-01

    mechanical response from poly(vinyl alcohol) does not differ from its static response. This result is not unexpected as poly(vinyl alcohol) is a highly flexible polymer with intramolecular relaxation processes taking place on a short time scale. The choice of a polymer with a fast relaxation allows its...... static properties to be recovered from the dynamic measurements and enables the method suggested in this paper for decoupling the polymer response from the hydrodynamic response to be validated....

  13. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    International Nuclear Information System (INIS)

    Brieger, M.

    2004-01-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  14. Integration of Plasticity Mechanisms within a Single Sensory Neuron of C. elegans Actuates a Memory.

    Science.gov (United States)

    Hawk, Josh D; Calvo, Ana C; Liu, Ping; Almoril-Porras, Agustin; Aljobeh, Ahmad; Torruella-Suárez, María Luisa; Ren, Ivy; Cook, Nathan; Greenwood, Joel; Luo, Linjiao; Wang, Zhao-Wen; Samuel, Aravinthan D T; Colón-Ramos, Daniel A

    2018-01-17

    Neural plasticity, the ability of neurons to change their properties in response to experiences, underpins the nervous system's capacity to form memories and actuate behaviors. How different plasticity mechanisms act together in vivo and at a cellular level to transform sensory information into behavior is not well understood. We show that in Caenorhabditis elegans two plasticity mechanisms-sensory adaptation and presynaptic plasticity-act within a single cell to encode thermosensory information and actuate a temperature preference memory. Sensory adaptation adjusts the temperature range of the sensory neuron (called AFD) to optimize detection of temperature fluctuations associated with migration. Presynaptic plasticity in AFD is regulated by the conserved kinase nPKCε and transforms thermosensory information into a behavioral preference. Bypassing AFD presynaptic plasticity predictably changes learned behavioral preferences without affecting sensory responses. Our findings indicate that two distinct neuroplasticity mechanisms function together through a single-cell logic system to enact thermotactic behavior. VIDEO ABSTRACT. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Brieger, M. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Physik

    2004-07-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  16. Crystal growth, structural, thermal and mechanical behavior of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals

    Science.gov (United States)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M.; Bhagavannarayana, G.; Hayakawa, Y.

    2014-12-01

    Single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of L-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

  17. Mechanical stability of a locked step-plate versus single compression screw fixation for medial displacement calcaneal osteotomy.

    Science.gov (United States)

    Konan, Sujith; Meswania, Jay; Blunn, Gordon W; Madhav, Rohit T; Oddy, Michael J

    2012-08-01

    Reconstruction of a flatfoot commonly involves a calcaneal Medial Displacement Osteotomy (MDO) to correct hindfoot valgus in combination with soft tissue procedures. We compared fixation of an MDO using either a single, large cannulated screw versus a locking step-plate in load to failure in a cadaveric model. Eight matched pairs of cadaveric limbs were loaded using a mechanical testing rig. Two pairs served as non-operated controls. The remaining paired limbs underwent a 10-mm MDO stabilized either with a single 7-mm screw or a step-plate with four locking screws. One pair was used as a pilot study and the remaining five pairs were loaded up to 4500 N to failure. In the five pairs loaded to failure, the median (with 95% CI) maximum force were 1779 N (1099-2312) and 826 N (288-1607) for the plate and screw, respectively (p = 0.043). With single screw fixation, the tuberosity fragment consistently failed by rotation and angulation into varus. With plate fixation, failure occurred as the screws cut through the internal surfaces of the tuberosity and body with no failure at the screw-plate interface. In this cadaveric model, a locked step-plate supported a significantly higher maximum force than a single large cannulated screw. The magnitude of the load supported by the locking step-plate suggests that allowing early weightbearing post-operation may be safe in clinical practice before union of the osteotomy.

  18. Draft forces prediction model for standard single tines by using principles of soil mechanics and soil profile evaluation

    Directory of Open Access Journals (Sweden)

    Amer Khalid Ahmed Al-Neama

    2017-06-01

    Full Text Available This paper explains a model to predict the draft force acting on varying standard single tines by using principles of soil mechanics and soil profile evaluation. Draft force (Fd measurements were made with four standard single tines comprising Heavy Duty, Double Heart, Double Heart with Wings and Duck Foot. Tine widths were 6.5, 13.5, 45 and 40 cm, respectively. The test was conducted in a soil bin with sandy loam soil. The effects of forward speeds and working depths on draft forces were investigated under controlled lab conditions. Results were evaluated based on a prediction model. A good correlation between measured and predicted Fd values for all tines with an average absolute variation less than 15 % was found.

  19. Influence of composition on the microstructure and mechanical properties of a nickel-base superalloy single crystal

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1984-01-01

    The effects of cobalt, tantalum, and tungsten contents on the microstructure and mechanical properties of single crystal Mar-M247 were investigated. Elevated temperature tensile and creep-rupture properties of 001 oriented single crystals were related to microstructural features of the alloys. Substitution of Ni for Co in the high refractory metal alloys increased the lattice mismatch, which was considered to be the cause of the increases in tensile and creep strength. Substitution of Ni for Ta caused large decreases in tensile strength and creep life, consistent with decreases in gamma prime volume fraction, lattice mismatch, and solid solution hardening. Substitution of W for Ta resulted in decreased life at high stresses, which was related to small decreases in mismatch and volume fraction. However, the W substitution resulted in improved life at low stresses, which was related to solid solution strengthening by W.

  20. Effects of low temperature neutron irradiation on the mechanical properties of iron single crystals

    International Nuclear Information System (INIS)

    Kitajima, K.; Abe, H.; Takamura, S.; Okuda, S.

    1975-01-01

    Measurements were made on tensile properties and their recovery characteristics of single crystals of pure iron and iron containing carbon of 4 to 60 ppm irradiated in reactor to the dose of 3 x 10 16 to approximately 3 x 10 17 nvt (greater than 0.1 MeV) at approximately 5 0 K. The yield stress showed large softening at less than or equal to 90 0 K saturating to a value nearly independent of orientations for greater than or equal to 1 x 10 17 nvt. The softening recovered and hardening set in at several temperature stages. The activation energies of the recovery and the activation parameters of plastic deformations at various annealing stages were determined. Carbon suppressed the softening and its recovery but much enhanced the hardening at the stage of 300 to approximately 400 0 K

  1. Effect of grain defects on the mechanical behavior of nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haibin; Guo, Haiding [Nanjing Univ. of Aeronautics and Astronautics (China). Jiangsu Province Key Lab. of Aerospace Power System

    2017-03-15

    In this paper, a single crystal (SC) partition model, consisting of primary grains and grain defects, is proposed to simulate the weakening effect of grain defects generated at geometric discontinuities of SC materials. The plastic deformation of SC superalloy is described with the modified yield criterion, associated flow rule and hardening law. Then a bicrystal model containing only one group of misoriented grains under uniaxial loading is constructed and analyzed in the commercial finite element software ABAQUS. The simulation results indicate that the yield strength and elastic modulus of misoriented grains, which are determined by the crystallographic orientation, have a significant effect on the stress distribution of the bicrystal model. A critical stress, which is calculated by the stress state at critical regions, is proposed to evaluate the local stress rise at the sub-boundary of primary and misoriented grains.

  2. Electronic properties of dislocations introduced mechanically at room temperature on a single crystal silicon surface

    International Nuclear Information System (INIS)

    Ogawa, Masatoshi; Kamiya, Shoji; Izumi, Hayato; Tokuda, Yutaka

    2012-01-01

    This paper focuses on the effects of temperature and environment on the electronic properties of dislocations in n-type single crystal silicon near the surface. Deep level transient spectroscopy (DLTS) analyses were carried out with Schottky electrodes and p + -n junctions. The trap level, originally found at E C -0.50 eV (as commonly reported), shifted to a shallower level at E C -0.23 eV after a heat treatment at 350 K in an inert environment. The same heat treatment in lab air, however, did not cause any shift. The trap level shifted by the heat treatment in an inert environment was found to revert back to the original level when the specimens were exposed to lab air again. Therefore, the intrinsic trap level is expected to occur at E C -0.23 eV and shift sensitively with gas adsorption in air.

  3. PEDIATRIC HEAD INJURIES, MECHANISM TO MANAGEMENT: EXPERIENCE OF A SINGLE CENTER

    Directory of Open Access Journals (Sweden)

    Pankaj

    2016-01-01

    Full Text Available INTRODUCTION Head injury is very common in modern life. Patients of any age group may have head injury however mechanism of head injury, pathophysiology and outcome of head injury is quite different in adults as compared to children. Road traffic accident is a common mode of head injury in adults while fall from height and household abuse is common mode in children. In Western countries, there is a separate registry system for pediatric head injury but there is no such system exist in india. Our present study is focused on pediatric head injury and evaluation of factors that affect the final outcome in pediatric patients.

  4. Change-over natural and mechanical ventilation system energy consumption in single-family buildings

    Science.gov (United States)

    Kostka, Maria; Szulgowska-Zgrzywa, Małgorzata

    2017-11-01

    The parameters of the outside air in Poland cause that in winter it is reasonable to use a mechanical ventilation equipped with a heat recovery exchanger. The time of spring, autumn, summer evenings and nights are often characterized by the parameters of the air, which allow for a natural ventilation and reduce the electricity consumption. The article presents the possibilities of energy consumption reduction for three energy standards of buildings located in Poland, ventilated by a change-over hybrid system. The analysis was prepared on the assumption that the air-to-water heat pump is the heat source for the buildings.

  5. Mechanical unfolding of proteins: reduction to a single-reaction coordinate unfolding potential, and an application of the Jarzynski Relation

    Science.gov (United States)

    Olmsted, Peter; West, Daniel; Paci, Emanuele

    2007-03-01

    Single molecule force spectroscopy (AFM, optical tweezers, etc) has revolutionized the study of many biopolymers, including DNA, RNA, and proteins. In this talk I will discuss recent work on modelling of mechanical unfolding of proteins, as often probed by AFM. I will address two issues in obtaining a coarse-grained description of protein unfolding: how to project the entire energy landscape onto an effective one dimensional unfolding potential, and how to apply the Jarzynski Relation to extract equilibrium free energies from nonequilibrium unfolding experiments.

  6. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Alstrup, J.; Norrman, K.; Jørgensen, M.

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...... of degradation products from different parts of the molecule. Photovoltaic devices with and without C(60) have been prepared and their characteristics under AM1.5 conditions are reported. The degradation of the active phenylene-vinylene compound in darkness and after 20h of illumination were investigated using...

  7. The “Liberty” of Work and the Traps of Piece Work

    Directory of Open Access Journals (Sweden)

    Maria Augusta Tavares

    2009-01-01

    Full Text Available This article analyzes the relations of production in the sugarcane industry, identifying pay for piece work as a mechanism used by capital to intensify the productive capacity of workers and increase exploitation. The paper demonstrates that this form of pay, which is adjusted to flexible accumulation, far from guaranteeing the autonomy and liberty promised, reduces the time of socially necessary work, and therefore the value of the work force. The analysis uses Marxist economic categories to make clear that the labor protection laws do not resist the determinations of capital. The paper thus intends to reveal the inadequacy of policies in relation to the social question as a whole.

  8. Organization of DNA partners and strand exchange mechanisms during Flp site-specific recombination analyzed by difference topology, single molecule FRET and single molecule TPM.

    Science.gov (United States)

    Ma, Chien-Hui; Liu, Yen-Ting; Savva, Christos G; Rowley, Paul A; Cannon, Brian; Fan, Hsiu-Fang; Russell, Rick; Holzenburg, Andreas; Jayaram, Makkuni

    2014-02-20

    Flp site-specific recombination between two target sites (FRTs) harboring non-homology within the strand exchange region does not yield stable recombinant products. In negatively supercoiled plasmids containing head-to-tail sites, the reaction produces a series of knots with odd-numbered crossings. When the sites are in head-to-head orientation, the knot products contain even-numbered crossings. Both types of knots retain parental DNA configuration. By carrying out Flp recombination after first assembling the topologically well defined Tn3 resolvase synapse, it is possible to determine whether these knots arise by a processive or a dissociative mechanism. The nearly exclusive products from head-to-head and head-to-tail oriented "non-homologous" FRT partners are a 4-noded knot and a 5-noded knot, respectively. The corresponding products from a pair of native (homologous) FRT sites are a 3-noded knot and a 4-noded catenane, respectively. These results are consistent with non-homology-induced two rounds of dissociative recombination by Flp, the first to generate reciprocal recombinants containing non-complementary base pairs and the second to produce parental molecules with restored base pairing. Single molecule fluorescence resonance energy transfer (smFRET) analysis of geometrically restricted FRTs, together with single molecule tethered particle motion (smTPM) assays of unconstrained FRTs, suggests that the sites are preferentially synapsed in an anti-parallel fashion. This selectivity in synapse geometry occurs prior to the chemical steps of recombination, signifying early commitment to a productive reaction path. The cumulative topological, smFRET and smTPM results have implications for the relative orientation of DNA partners and the directionality of strand exchange during recombination mediated by tyrosine site-specific recombinases. Copyright © 2013. Published by Elsevier Ltd.

  9. Internal mechanical stresses and the thermodynamic and adhesion parameters of the metal condensate-single-crystal silicon system

    Science.gov (United States)

    Coman, B. P.; Juzevych, V. N.

    2012-07-01

    The kinetics of generation of internal mechanical stresses σ( d) in chromium, copper, gold, and aluminum thin films on single-crystal silicon substrates at different deposition rates has been experimentally investigated using the cantilever method. A two-step character of the variations in internal tensile stresses has been revealed. The regularities of the formation of the maximum level of mechanical stresses in the condensates under investigation have been established. The energy and adhesion parameters of chromium, copper, gold, and aluminum nanolayers on silicon, germanium, and nickel substrates have been studied using the macroscopic methods of surface physics. The interfacial energy, interfacial tension, work of adhesion, interfacial charge, and a new energy characteristic of the interfacial layer, namely, the energy of adhesive bonds, which exceeds the interfacial energy, have been determined.

  10. Emergence of azole resistance in Aspergillus fumigatus and spread of a single resistance mechanism.

    Directory of Open Access Journals (Sweden)

    Eveline Snelders

    2008-11-01

    Full Text Available BACKGROUND: Resistance to triazoles was recently reported in Aspergillus fumigatus isolates cultured from patients with invasive aspergillosis. The prevalence of azole resistance in A. fumigatus is unknown. We investigated the prevalence and spread of azole resistance using our culture collection that contained A. fumigatus isolates collected between 1994 and 2007. METHODS AND FINDINGS: We investigated the prevalence of itraconazole (ITZ resistance in 1,912 clinical A. fumigatus isolates collected from 1,219 patients in our University Medical Centre over a 14-y period. The spread of resistance was investigated by analyzing 147 A. fumigatus isolates from 101 patients, from 28 other medical centres in The Netherlands and 317 isolates from six other countries. The isolates were characterized using phenotypic and molecular methods. The electronic patient files were used to determine the underlying conditions of the patients and the presence of invasive aspergillosis. ITZ-resistant isolates were found in 32 of 1,219 patients. All cases were observed after 1999 with an annual prevalence of 1.7% to 6%. The ITZ-resistant isolates also showed elevated minimum inhibitory concentrations of voriconazole, ravuconazole, and posaconazole. A substitution of leucine 98 for histidine in the cyp51A gene, together with two copies of a 34-bp sequence in tandem in the gene promoter (TR/L98H, was found to be the dominant resistance mechanism. Microsatellite analysis indicated that the ITZ-resistant isolates were genetically distinct but clustered. The ITZ-sensitive isolates were not more likely to be responsible for invasive aspergillosis than the ITZ-resistant isolates. ITZ resistance was found in isolates from 13 patients (12.8% from nine other medical centres in The Netherlands, of which 69% harboured the TR/L98H substitution, and in six isolates originating from four other countries. CONCLUSIONS: Azole resistance has emerged in A. fumigatus and might be more

  11. Electric-field-tunable mechanical properties of relaxor ferroelectric single crystal measured by nanoindentation

    Science.gov (United States)

    Zhou, Hao; Pei, Yongmao; Li, Faxin; Luo, Haosu; Fang, Daining

    2014-02-01

    Electric field dependent mechanical properties of relaxor ferroelectric material Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation technique. Giant electric-field-tunable apparent elastic modulus (up to -39%), hardness (-9% to 20%), and energy dissipation (up to -13%) are reported. Based on experimental data, a characterization method of electromechanical coupled nanoindentation is proposed. In this method, an electric field tunable scaling relationship among elastic modulus, hardness, and indentation work for ferroelectric materials can be determined. In addition, this method can be used to obtain the electric-field-dependent elastic modulus and hardness, and avoid the estimate of contact area in the Oliver-Pharr method. Finally, the different effects on elastic modulus between positive and negative electric fields can be explained by the flexoelectric effect.

  12. Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography

    Energy Technology Data Exchange (ETDEWEB)

    Ciccarelli, G. (Brookhaven National Lab., Dept. of Advanced Technology, Upton, NY (United States)); Frost, D.L. (Mechanical Engineering Dept., McGill Univ., Montreal, PQ (Canada))

    1994-02-01

    Flash X-ray and high-speed regular photography were used to investigate the fragmentation processes during the vapor explosion of single drops of molten metal immersed in water. For relatively low ambient flow velocities (<5 m/s), a comparison of the breakup of hot and cold drops shows that whereas cold drops breakup due to the stripping of fragments by the relative flow, the fragmentation of a hot drop is dominated by the growth and collapse of a vapor bubble. X-ray radiographs show during the growth of the bubble, that fine filaments of metal protrude from the drop and the drop surface becomes highly convoluted. Using a simple model for the bubble dynamics, an estimate of the energy budget shows that the majority (about 80%) of the thermal energy transfer occurs during bubble collapse. For hot drops at higher flow velocities (>45 m/s), vapor bubble growth is diminished and high-speed motion of vapor within the bubble leads to an enhanced fragmentation rate. (orig.)

  13. Efficient single-pixel multispectral imaging via non-mechanical spatio-spectral modulation.

    Science.gov (United States)

    Li, Ziwei; Suo, Jinli; Hu, Xuemei; Deng, Chao; Fan, Jingtao; Dai, Qionghai

    2017-01-27

    Combining spectral imaging with compressive sensing (CS) enables efficient data acquisition by fully utilizing the intrinsic redundancies in natural images. Current compressive multispectral imagers, which are mostly based on array sensors (e.g, CCD or CMOS), suffer from limited spectral range and relatively low photon efficiency. To address these issues, this paper reports a multispectral imaging scheme with a single-pixel detector. Inspired by the spatial resolution redundancy of current spatial light modulators (SLMs) relative to the target reconstruction, we design an all-optical spectral splitting device to spatially split the light emitted from the object into several counterparts with different spectrums. Separated spectral channels are spatially modulated simultaneously with individual codes by an SLM. This no-moving-part modulation ensures a stable and fast system, and the spatial multiplexing ensures an efficient acquisition. A proof-of-concept setup is built and validated for 8-channel multispectral imaging within 420~720 nm wavelength range on both macro and micro objects, showing a potential for efficient multispectral imager in macroscopic and biomedical applications.

  14. Zn Electrodeposition on Single-Crystal GaN(0001 Surface: Nucleation and Growth Mechanism

    Directory of Open Access Journals (Sweden)

    Fei Peng

    2016-01-01

    Full Text Available The electrochemical deposition of zinc on single-crystal n-type GaN(0001 from a sulphate solution has been investigated on the basis of electrochemical techniques including cyclic voltammetry, chronoamperometry, and Tafel plot. The morphology and crystal structure of zinc deposits have been characterized by means of scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The result has revealed that the deposition of Zn on GaN electrode commenced at a potential of −1.12 V versus Ag/AgCl. According to the Tafel plot, an exchange current density of ~0.132 mA cm−2 was calculated. In addition, the current transient measurements have shown that Zn deposition process followed the instantaneous nucleation in 10 mM ZnSO4 + 0.5 M Na2SO4 + 0.5 M H3BO3 (pH = 4.

  15. Electrochemical deposition of copper on single-crystal gallium nitride(0001) electrode: nucleation and growth mechanism

    International Nuclear Information System (INIS)

    Zhao, Yu; Deng, Feng-Xiang; Hu, Li-Feng; Liu, Yong-Qiang; Pan, Ge-Bo

    2014-01-01

    Highlights: • The nucleation and growth of Cu electrodeposition on n-GaN was explored. • The Cu deposition commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ . • The deposition process was quasi-reversible and mass transfer limited. • The deposition occurred on the conduction band of n-GaN. - Abstract: The electrodeposition of Cu on n-type single-crystal GaN(0001) electrode from sulfate solution was investigated by electrochemical techniques and scanning electron microscopy. It was found that Cu deposition on GaN(0001) commenced at a large negative potential of −840 mV vs. Pt/Pt 2+ and was quasi-reversible and mass transfer limited. On the basis of Tafel plot, a low exchange current density of ∼ 2.3 × 10 −6 mA cm −2 was calculated. This was mainly due to the limited free electrons in the conduction band of GaN. In addition, the current transient measurements revealed that the deposition process followed the progressive nucleation in 0.5 M H 2 SO 4 + 5 mM CuSO 4 . The instantaneous nucleation was observed only at the large applied potential of −1.1 V

  16. Transport of single-walled carbon nanotubes in porous media: filtration mechanisms and reversibility.

    Science.gov (United States)

    Jaisi, Deb P; Saleh, Navid B; Blake, Ruth E; Elimelech, Menachem

    2008-11-15

    Deposition of nanomaterials onto surfaces is a key process governing their transport, fate, and reactivity in aquatic systems. We evaluated the transport and deposition behavior of carboxyl functionalized single-walled carbon nanotubes (SWNTs) in a well-defined porous medium composed of clean quartz sand over a range of solution chemistries. Our results showthat increasing solution ionic strength or addition of calcium ions result in increased SWNT deposition (filtration). This observation is consistent with conventional colloid deposition theories, thereby suggesting that physicochemical filtration plays an important role in SWNT transport. However, the relatively insignificant change of SWNT filtration at low ionic strengths (water (C/Co = 0.90) indicate that physical straining also plays a role in the capture of SWNTs within the packed sand column. It is proposed that SWNT shape and structure, particularly the very large aspect ratio and its highly bundled (aggregated) state in aqueous solutions, contribute considerably to straining in flow through porous media. We conclude that both physicochemical filtration and straining play a role at low (introduction of low ionic strength solution following deposition experiments with monovalent salt (KCl). In contrast, SWNTs deposited in the presence of calcium ions were not released upon introduction of low ionic strength solution to the packed column, even when humic acid was present in solution during SWNT deposition.

  17. Overexpression of cypin alters dendrite morphology, single neuron activity, and network properties via distinct mechanisms

    Science.gov (United States)

    Rodríguez, Ana R.; O'Neill, Kate M.; Swiatkowski, Przemyslaw; Patel, Mihir V.; Firestein, Bonnie L.

    2018-02-01

    Objective. This study investigates the effect that overexpression of cytosolic PSD-95 interactor (cypin), a regulator of synaptic PSD-95 protein localization and a core regulator of dendrite branching, exerts on the electrical activity of rat hippocampal neurons and networks. Approach. We cultured rat hippocampal neurons and used lipid-mediated transfection and lentiviral gene transfer to achieve high levels of cypin or cypin mutant (cypinΔPDZ PSD-95 non-binding) expression cellularly and network-wide, respectively. Main results. Our analysis revealed that although overexpression of cypin and cypinΔPDZ increase dendrite numbers and decrease spine density, cypin and cypinΔPDZ distinctly regulate neuronal activity. At the single cell level, cypin promotes decreases in bursting activity while cypinΔPDZ reduces sEPSC frequency and further decreases bursting compared to cypin. At the network level, by using the Fano factor as a measure of spike count variability, cypin overexpression results in an increase in variability of spike count, and this effect is abolished when cypin cannot bind PSD-95. This variability is also dependent on baseline activity levels and on mean spike rate over time. Finally, our spike sorting data show that overexpression of cypin results in a more complex distribution of spike waveforms and that binding to PSD-95 is essential for this complexity. Significance. Our data suggest that dendrite morphology does not play a major role in cypin action on electrical activity.

  18. Electronic transport mechanism and photocurrent generations of single-crystalline InN nanowires

    Science.gov (United States)

    Lee, Sunghun; Lee, Wonjoo; Seo, Kwanyong; Kim, Jinhee; Han, Sung-Hwan; Kim, Bongsoo

    2008-10-01

    Nanodevices using individual indium nitride nanowires are fabricated by e-beam lithography. The nanowires have diameters of 40-80 nm, lengths up to several tens of micrometres and single-crystalline nature. We observed ohmic I-V behaviour of InN nanowires above nearly 100 K, which is consistent with the pinning Fermi level of the metal electrode near the conduction band edge of InN nanowire. At low temperatures, the device shows typical semiconductor behaviour along with a quantum tunnelling effect through the Schottky barrier rather than thermally activated transport. The activation energy calculated above and below 80 K is 28.2 and 5.08 meV, respectively. We have also fabricated a photocurrent generation device using InN nanowires. The photocurrent of an acceptor-sensitizer dyad with di-(3-aminopropyl)-viologen (DAPV) and a Ru complex on an InN nanowires/ITO plate was 8.3 nA cm-2, which increased by 62.7% compared to that without InN nanowire layers.

  19. Fabrication of a mechanically aligned single-wafer MEMS turbine with turbocharger

    Science.gov (United States)

    Pelekies, S. O.; Schuhmann, T.; Gardner, W. G.; Camacho, A.; Protz, J. M.

    2010-10-01

    We describe the fabrication of a turbocharged, microelectromechanical system (MEMS) turbine. The turbine will be part of a standalone power unit and includes extra layers to connect the turbine to a generator. The project goal is to demonstrate the successful combination of several features, namely: silicon fusion bonding (SFB), a micro turbocharger [2], two rotors, mechanical alignment between two wafers [1], and the use of only one 5" silicon wafer. The dimension of the actual turbine casing will be 14mm. The turbine rotor will have a diameter of 8mm. Given these dimensions, MEMS processes are an adequate way to fabricate the device, but it will be necessary to stack up seven different layers to build the turbine, as it is not possible to construct it out of one thick wafer. SFB will be used for bonding because it permits the great precision necessary for high quality alignment. Yet a more precise alignment will be necessary between the layers that contain the turbine rotor, to decrease imbalance and guarantee operation at a very high rpm. To achieve these tight tolerances, a mechanical alignment feature announced by Liudi Jiang [1] is used. The alignment accuracy is expected to be around 200nm. Despite the fact that the turbine consists of multiple layers, it will be fabricated on only one silicon-on-insulator (SOI) wafer. As a result, all layers are exposed to the same process flow. The fabrication process includes MEMS technology as photolithography, nine deep reactive ion etching (DRIE) steps, and six SFB operations. A total of 14 masks are necessary for the fabrication.

  20. Elastic hydrogel as a sensor for detection of mechanical stress generated by single cells grown in three-dimensional environment.

    Science.gov (United States)

    Huang, Jianyong; Wang, Liangli; Xiong, Chunyang; Yuan, Fan

    2016-08-01

    Cell volume growth occurs in all living tissues. The growth exerts mechanical stresses on surrounding tissues that may alter tissue microenvironment, and have significant implications in health and diseases. However, the level of growth stress generated by single cells in three-dimensional (3D) environment remains to be determined. To this end, we developed a growth force microscopy technique to determine 3D distribution of the stress. The technique was based on encapsulation of cells in elastic hydrogels, and involved 3D particle tracking and mechanical analysis of gel deformation. Data from the study demonstrated that the growth stress was dynamic, and the stress distribution at the gel-cell interface was correlated inversely to the mean surface curvature or the distance to the geometric center of the cell. The stress averaged over the cell surface increased with increasing gel stiffness, suggesting that cells could alter growth stress in response to stiffness change in microenvironment. These findings suggested that the elastic hydrogel-based microscopy technique had a potential to provide new insights into mechanisms of mechanical interactions between cell and its microenvironment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Dynamic quantitative visualization of single cell alignment and migration and matrix remodeling in 3-D collagen hydrogels under mechanical force.

    Science.gov (United States)

    Pang, Yonggang; Wang, Xiaoli; Lee, Dongkeun; Greisler, Howard P

    2011-05-01

    We developed a live imaging system enabling dynamic visualization of single cell alignment induced by external mechanical force in a 3-D collagen matrix. The alignment dynamics and migration of smooth muscle cells (SMCs) were studied by time lapse differential interference contrast and/or phase contrast microscopy. Fluorescent and reflection confocal microcopy were used to study the SMC morphology and the microscale collagen matrix remodeling induced by SMCs. A custom developed program was used to quantify the cell migration and matrix remodeling. Our system enables cell concentration-independent alignment eliminating cell-to-cell interference and enables dynamic cell tracking, high magnification observation and rapid cell alignment accomplished in a few hours compared to days in traditional models. We observed that cells sense and response to the mechanical signal before cell spreading. Under mechanical stretch the migration directionality index of SMCs is 46.3% more than those cells without external stretch; the dynamic direction of cell protrusion is aligned to that of the mechanical force; SMCs showed directional matrix remodeling and the alignment index calculated from the matrix in front of cell protrusions is about 3 fold of that adjacent to cell bodies. Our results indicate that the mechanism of cell alignment is directional cell protrusion. Mechano-sensing, directionality in cell protrusion dynamics, cell migration and matrix remodeling are highly integrated. Our system provides a platform for studying the role of mechanical force on the cell matrix interactions and thus finds strategies to optimize selected properties of engineered tissues. Published by Elsevier Ltd.

  2. Inspection of complex geometry pieces with an intelligent contact transducer

    International Nuclear Information System (INIS)

    Chatillon, S.; Roy, O.; Mahaut, St.

    2000-01-01

    A new multi-element contact transducer has been developed to improve the inspection of components with complex geometry. The emitting surface is flexible in order to optimize the contact with pieces. An algorithm, based on a simplified geometric model, has been used to determine the delays law which allows to control the focal characteristics of the transmitted field. Acquisition data lead in transmission with an articulated transducer validate the behavior provided by simulation. Thus the optimization of the delays law ensures the transmission of a beam which is homogeneous and controlled during the moving of the transducer. Inspections in echo-pulse mode are implemented on a sample simulating a component controlled on site. Results show that the dynamical adaptation of the delays law to the geometry of the piece leads to very good performances

  3. Scleral fixation of one piece intraocular lens by injector implantation.

    Science.gov (United States)

    Can, Ertugrul; Basaran, Resat; Gul, Adem; Birinci, Hakki

    2014-08-01

    With an ab-interno technique of transscleral suturing of current one-piece posterior chamber intraocular lenses (PC IOLs) by injector implantation in the absence of capsular support, we aimed to demonstrate the possibility of the implantation of one-piece acrylic PC IOLs that might be produced in the future for only scleral fixation through small clear corneal incision. Case report and literature review. This procedure has been performed in eight aphakic eyes with four different types of IOLs. Good centration was achieved with minimal technical effort. All patients had well-centered and stable lenses postoperatively during 9-18 months follow-up. We managed to decrease the risks of surgical trauma and intricate surgical maneuvers requirement. With this technique, excessive fluid leakage and consecutive hypotony can be minimized.

  4. Device to detect faults on the surfaces of work pieces

    International Nuclear Information System (INIS)

    Savidge, D.H.; Wadsworth, E.

    1979-01-01

    The surface of a work piece, e.g. a steel block, can be scanned by a high-frequency induced eddy current probe. The probe forms the inductive part of a tuned high-frequency oscillator circuit. A buffer amplifier separates the frequency and the amplitude of the output signals received by the oscillator circuit and feeds these to a double-channel receiver. The scanning head can also have several probe coils. (RW) [de

  5. Exploring particulate retention mechanisms through visualization of E. coli transport through a single, saturated fracture

    Science.gov (United States)

    Burke, M. G.; Dickson, S. E.; Schutten, M.

    2011-12-01

    Groundwater is an extremely valuable resource; a large body of work has been conducted towards remediating, tracking and reducing its contamination. Even so, there are large gaps within the current understanding of groundwater flow and contaminant transport, particularly within fractured media. Fractured media has the ability transport contaminants over longer distances in less time relative to porous media. Furthermore, colloids display unique transport characteristics in comparison to dissolved constituents, including the fact that they typically exhibit earlier initial arrival times. Of particular concern to human health are pathogenic microorganisms, which often originate from fecal contamination. Escherichia coli is a common indicator for fecal contamination; some strains are pathogenic, causing acute illness and sometimes death, in humans. A comprehensive understanding of the transport and retention of E. coli in fractured media will improve our ability to accurately assess whether a site is at risk of becoming contaminated by pathogenic microorganisms. Therefore, the goal of this work is to expand our mechanistic understanding particulate retention, specifically E. coli, in fractures, and the influence of flow rate on these mechanisms. In order to achieve this goal, clear epoxy casts were fabricated of two dolomitic limestone fractures retrieved from a quarry in Guelph, Ontario. Each aperture field was characterized through hydraulic and tracer tests, and measured directly using the light transmission technique. E. coli RS2-GFP, which is a non-pathogenic strain of E. coli that has been tagged with a green fluorescent protein, was injected into the cast under three separate specific discharges ranging from 5 - 30 m/d. These experiments were conducted on an ultraviolet light source, and a high resolution charged-couple device (CCD) camera was employed to take photos at regular intervals in order to capture the dominant flow paths and the areas of retention

  6. Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications

    Directory of Open Access Journals (Sweden)

    Cherneva Sabina

    2018-01-01

    Full Text Available Single thin coating of matt nickel (Nimat, a mirror bright copper (Cubright, a mirror bright nickel (Nibright and their combinations were electrochemically deposited on brass substrate with thickness 500 μm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 μm to 3.25 μm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system “protective coating/substrate” to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings.

  7. A polypeptide-DNA hybrid with selective linking capability applied to single molecule nano-mechanical measurements using optical tweezers.

    Directory of Open Access Journals (Sweden)

    Fatemeh Moayed

    Full Text Available Many applications in biosensing, biomaterial engineering and single molecule biophysics require multiple non-covalent linkages between DNA, protein molecules, and surfaces that are specific yet strong. Here, we present a novel method to join proteins and dsDNA molecule at their ends, in an efficient, rapid and specific manner, based on the recently developed linkage between the protein StrepTactin (STN and the peptide StrepTag II (ST. We introduce a two-step approach, in which we first construct a hybrid between DNA and a tandem of two STs peptides (tST. In a second step, this hybrid is linked to polystyrene bead surfaces and Maltose Binding Protein (MBP using STN. Furthermore, we show the STN-tST linkage is more stable against forces applied by optical tweezers than the commonly used biotin-Streptavidin (STV linkage. It can be used in conjunction with Neutravidin (NTV-biotin linkages to form DNA tethers that can sustain applied forces above 65 pN for tens of minutes in a quarter of the cases. The method is general and can be applied to construct other surface-DNA and protein-DNA hybrids. The reversibility, high mechanical stability and specificity provided by this linking procedure make it highly suitable for single molecule mechanical studies, as well as biosensing and lab on chip applications.

  8. Thermo-Mechanical Analysis of a Single-Pass Weld Overlay and Girth Welding in Lined Pipe

    Science.gov (United States)

    Obeid, Obeid; Alfano, Giulio; Bahai, Hamid

    2017-08-01

    The paper presents a nonlinear heat-transfer and mechanical finite-element (FE) analyses of a two-pass welding process of two segments of lined pipe made of a SUS304 stainless steel liner and a C-Mn steel pipe. The two passes consist of the single-pass overlay welding (inner lap weld) of the liner with the C-Mn steel pipe for each segment and the single-pass girth welding (outer butt weld) of the two segments. A distributed power density of the moving welding torch and a nonlinear heat-transfer coefficient accounting for both radiation and convection have been used in the analysis and implemented in user subroutines for the FE code ABAQUS. The modeling procedure has been validated against previously published experimental results for stainless steel and carbon steel welding separately. The model has been then used to determine the isotherms induced by the weld overlay and the girth welding and to clarify their influence on the transient temperature field and residual stress in the lined pipe. Furthermore, the influence of the cooling time between weld overlay and girth welding and of the welding speed have been examined thermally and mechanically as they are key factors that can affect the quality of lined pipe welding.

  9. PieceStack: Toward Better Understanding of Stacked Graphs.

    Science.gov (United States)

    Wu, Tongshuang; Wu, Yingcai; Shi, Conglei; Qu, Huamin; Cui, Weiwei

    2016-02-24

    Stacked graphs have been widely adopted in various fields, because they are capable of hierarchically visualizing a set of temporal sequences as well as their aggregation. However, because of visual illusion issues, connections between overly-detailed individual layers and overly-generalized aggregation are intercepted. Consequently, information in this area has yet to be fully excavated. Thus, we present PieceStack in this paper, to reveal the relevance of stacked graphs in understanding intrinsic details of their displayed shapes. This new visual analytic design interprets the ways through which aggregations are generated with individual layers by interactively splitting and re-constructing the stacked graphs. A clustering algorithm is designed to partition stacked graphs into sub-aggregated pieces based on trend similarities of layers. We then visualize the pieces with augmented encoding to help analysts decompose and explore the graphs with respect to their interests. Case studies and a user study are conducted to demonstrate the usefulness of our technique in understanding the formation of stacked graphs.

  10. Advanced Propfan Engine Technology (APET) definition study, single and counter-rotation gearbox/pitch change mechanism design

    Science.gov (United States)

    Anderson, R. D.

    1985-01-01

    Single-rotation propfan-powered regional transport aircraft were studied to identify key technology development issues and programs. The need for improved thrust specific fuel consumption to reduce fuel burned and aircraft direct operating cost is the dominant factor. Typical cycle trends for minimizing fuel consumption are reviewed, and two 10,000 shp class engine configurations for propfan propulsion systems for the 1990's are presented. Recommended engine configurations are both three-spool design with dual spool compressors and free power turbines. The benefits of these new propulsion system concepts were evaluated using an advanced airframe, and results are compared for single-rotation propfan and turbofan advanced technology propulsion systems. The single-rotation gearbox is compared to a similar design with current technology to establish the benefits of the advanced gearbox technology. The conceptual design of the advanced pitch change mechanism identified a high pressure hydraulic system that is superior to the other contenders and completely external to the gearboxes.

  11. A single-patterned five-band terahertz metamaterial absorber based on multiple resonance mechanisms

    Science.gov (United States)

    Ju, Zong-De; Xu, Guo-Qing; Wei, Zhi-Hua; Li, Jing; Zhao, Qian; Huang, Jie

    2018-01-01

    A single-patterned five-band terahertz metamaterial absorber based on simple metal-dielectric-metal sandwich structure is investigated and demonstrated. The numerical simulations reveal the different dependence of the absorption ability on the incident polarization angle, dielectric layer, and structural dimensions of the single pattern. The extracted electric field distribution indicates that the five-band near-perfect absorption performance (average over 98%) mainly originates from the combination of LC, dipole, quadrupole, and high-order resonance. The researches on magnetic field and power loss density distributions further reveal the absorption mechanism. Moreover, additional resonance mode can be excited to form a six-band high-performance absorber only by adjusting some geometric dimensions of the single pattern with multiple resonance modes. The simple method provides us a very good idea to implement a super multi-band absorber. The proposed absorbers here can be applied in massive related fields, such as metamaterial sensors, thermal radiation, and imaging system.

  12. Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam (India); Baby, C. [Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai (India); Gopalakrishnan, R. [Crystal Research Lab, Department of Physics, Anna University, Chennai (India)

    2016-09-15

    Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

  13. Foot muscle morphology is related to center of pressure sway and control mechanisms during single-leg standing.

    Science.gov (United States)

    Zhang, Xianyi; Schütte, Kurt Heinrich; Vanwanseele, Benedicte

    2017-09-01

    Maintaining balance is vitally important in everyday life. Investigating the effects of individual foot muscle morphology on balance may provide insights into neuromuscular balance control mechanisms. This study aimed to examine the correlation between the morphology of foot muscles and balance performance during single-leg standing. Twenty-eight recreational runners were recruited in this study. An ultrasound device was used to measure the thickness and cross-sectional area of three intrinsic foot muscles (abductor hallucis, flexor digitorum brevis and quadratus plantae) and peroneus muscles. Participants were required to perform 30s of single-leg standing for three trials on a force plate, which was used to record the center of pressure (COP). The standard deviation of the amplitude and ellipse area of the COP were calculated. In addition, stabilogram diffusion analysis (SDA) was performed on COP data. Pearson correlation coefficients were computed to examine the correlation between foot muscle morphology and traditional COP parameters as well as with SDA parameters. Our results showed that larger abductor hallucis correlated to smaller COP sway, while larger peroneus muscles correlated to larger COP sway during single-leg standing. Larger abductor hallucis also benefited open-loop dynamic stability, as well as supported a more efficient transfer from open-loop to closed loop control mechanisms. These results suggest that the morphology of foot muscles plays an important role in balance performance, and that strengthening the intrinsic foot muscles may be an effective way to improve balance. Copyright © 2017. Published by Elsevier B.V.

  14. Simulation of Impinging Cooling Performance with Pin Fins and Mist Cooling Adopted in a Simplified Gas Turbine Transition Piece

    OpenAIRE

    Tao Xu; Hang Xiu; Junlou Li; Haichao Ge; Qing Shao; Guang Yang; Zhenglei Yu

    2014-01-01

    The gas turbine transition piece was simplified to a one-four cylinder double chamber model with a single row of impinging holes in the outer wall. Heat transfer augmentation in the coolant chamber was achieved through the use of pin fin structure and mist cooling, which could increase the turbulence and heat transfer efficiency. The present research is focused on heat transfer and pressure characteristics of the impinging cooling in the coolant chamber using FLUENT software. With the given d...

  15. Neuromuscular Control Mechanisms During Single-Leg Jump Landing in Subacute Ankle Sprain Patients: A Case Control Study.

    Science.gov (United States)

    Allet, Lara; Zumstein, Franziska; Eichelberger, Patric; Armand, Stéphane; Punt, Ilona M

    2017-03-01

    Optimal neuromuscular control mechanisms are essential for preparing, maintaining, and restoring functional joint stability during jump landing and to prevent ankle injuries. In subacute ankle sprain patients, neither muscle activity nor kinematics during jump landing has previously been assessed. To compare neuromuscular control mechanisms and kinematics between subacute ankle sprain patients and healthy persons before and during the initial contact phase of a 25-cm single-leg jump. Case-control study. University hospital. Fifteen patients with grade I or II acute ankle sprains were followed up after 4 weeks of conservative management not involving physical therapy. Subjects performed alternately 3 single-leg forward jumps of 25 cm (toe-to-heel distance) barefoot. Their results were compared with the data of 15 healthy subjects. Electromyographic (EMG) activity of the musculus (m.) gastrocnemius lateralis, m. tibialis anterior, and m. peroneus longus as well as kinematics for ankle, knee, and hip joint were recorded for pre-initial contact (IC) phase, post-initial contact phase, and reflex-induced phase. The results showed that EMG activity of the 3 muscles did not differ between ankle sprain patients (n = 15) and healthy persons (n = 15) for any of the analyzed time intervals (all P > .05). However, during the pre-IC phase, ankle sprain patients presented less plantar flexion, as well as during the post-IC phase after jump landing, compared to healthy persons (P ankle joint can lead to neuromuscular control mechanism disturbances through which functional instability might arise. III. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  16. 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

  17. 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

  18. 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

  19. Structural, mechanical and light yield characterisation of heat treated LYSO:Ce single crystals for medical imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Mengucci, P., E-mail: p.mengucci@univpm.it [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); André, G. [Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, 91191 Gif sur Yvette cedex (France); Auffray, E. [Department PH-CMX CERN, Route de Meyrin, 1211 Geneva 23 (Switzerland); Barucca, G. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Cecchi, C. [Dipartimento di Fisica e Geologia, Università di Perugia, Via A. Pascoli, 06123 Perugia (Italy); Chipaux, R. [CEA DSM/IRFU/SEDI, CE-Saclay, 91191 Gif sur Yvette cedex (France); Cousson, A. [Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, 91191 Gif sur Yvette cedex (France); Davì, F. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Di Vara, N. [Department PH-CMX CERN, Route de Meyrin, 1211 Geneva 23 (Switzerland); Rinaldi, D.; Santecchia, E. [Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy)

    2015-06-11

    Five single crystals of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) grown by the Czochralski method were submitted to structural characterisation by X-ray (XRD) and neutron (ND) diffraction, scanning (SEM) and transmission (TEM) electron microscopy and energy dispersive microanalysis (EDS). The Ultimate Tensile Strength (UTS), the Young Modulus (YM) and the Light Yield (LY) of the samples were also measured in order to correlate the mechanical and the optical behaviour of the crystals with the characteristics of their microstructure. Two of the samples analysed were also heat treated at 300 °C for 10 h to evidence possible variations induced by the temperature in the optical and mechanical response of the crystals. Results showed that the mean compositional variations evidenced by the structural analyses do not affect the mechanical and optical behaviour of the samples. On the contrary, the thermal treatment could induce the formation of coherent spherical particles (size 10 to 15 nm), not uniformly distributed inside the sample, that strongly reduce the UTS and YM values, but it does not affect the optical response of the crystal. This latter result was attributed to the low value of the heating temperature (300 °C) that is not sufficiently high to induce annealing of the oxygen vacancies traps that are responsible of the deterioration of the scintillation properties of the LYSO:Ce crystals. This study was carried out in the framework of the Crystal Clear Collaboration (CCC)

  20. Single or in Combination Antimicrobial Resistance Mechanisms of Klebsiella pneumoniae Contribute to Varied Susceptibility to Different Carbapenems

    Science.gov (United States)

    Tsai, Yu-Kuo; Liou, Ci-Hong; Fung, Chang-Phone; Lin, Jung-Chung; Siu, L. Kristopher

    2013-01-01

    Resistance to carbapenems has been documented by the production of carbapenemase or the loss of porins combined with extended-spectrum β-lactamases or AmpC β-lactamases. However, no complete comparisons have been made regarding the contributions of each resistance mechanism towards carbapenem resistance. In this study, we genetically engineered mutants of Klebsiella pneumoniae with individual and combined resistance mechanisms, and then compared each resistance mechanism in response to ertapenem, imipenem, meropenem, doripenem and other antibiotics. Among the four studied carbapenems, ertapenem was the least active against the loss of porins, cephalosporinases and carbapenemases. In addition to the production of KPC-2 or NDM-1 alone, resistance to all four carbapenems could also be conferred by the loss of two major porins, OmpK35 and OmpK36, combined with CTX-M-15 or DHA-1 with its regulator AmpR. Because the loss of OmpK35/36 alone or the loss of a single porin combined with bla CTX-M-15 or bla DHA-1-ampR expression was only sufficient for ertapenem resistance, our results suggest that carbapenems other than ertapenem should still be effective against these strains and laboratory testing for non-susceptibility to other carbapenems should improve the accurate identification of these isolates. PMID:24265784

  1. High Temperature Deformation Mechanism in Hierarchical and Single Precipitate Strengthened Ferritic Alloys by In Situ Neutron Diffraction Studies

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Clausen, Bjørn; Zhang, Shu Yan; Gao, Yanfei; Liaw, Peter K.

    2017-04-01

    The ferritic Fe-Cr-Ni-Al-Ti alloys strengthened by hierarchical-Ni2TiAl/NiAl or single-Ni2TiAl precipitates have been developed and received great attentions due to their superior creep resistance, as compared to conventional ferritic steels. Although the significant improvement of the creep resistance is achieved in the hierarchical-precipitate-strengthened ferritic alloy, the in-depth understanding of its high-temperature deformation mechanisms is essential to further optimize the microstructure and mechanical properties, and advance the development of the creep resistant materials. In the present study, in-situ neutron diffraction has been used to investigate the evolution of elastic strain of constitutive phases and their interactions, such as load-transfer/load-relaxation behavior between the precipitate and matrix, during tensile deformation and stress relaxation at 973 K, which provide the key features in understanding the governing deformation mechanisms. Crystal-plasticity finite-element simulations were employed to qualitatively compare the experimental evolution of the elastic strain during tensile deformation at 973 K. It was found that the coherent elastic strain field in the matrix, created by the lattice misfit between the matrix and precipitate phases for the hierarchical-precipitate-strengthened ferritic alloy, is effective in reducing the diffusional relaxation along the interface between the precipitate and matrix phases, which leads to the strong load-transfer capability from the matrix to precipitate.

  2. Security analysis with improved design of post-confirmation mechanism for quantum sealed-bid auction with single photons

    Science.gov (United States)

    Zhang, Ke-Jia; Kwek, Leong-Chuan; Ma, Chun-Guang; Zhang, Long; Sun, Hong-Wei

    2018-02-01

    Quantum sealed-bid auction (QSA) has been widely studied in quantum cryptography. For a successful auction, post-confirmation is regarded as an important mechanism to make every bidder verify the identity of the winner after the auctioneer has announced the result. However, since the auctioneer may be dishonest and collude with malicious bidders in practice, some potential loopholes could exist. In this paper, we point out two types of collusion attacks for a particular post-confirmation technique with EPR pairs. And it is not difficult to see that there exists no unconditionally secure post-confirmation mechanism in the existing QSA model, if the dishonest participants have the ability to control multiparticle entanglement. In the view of this, we note that some secure implementation could exist if the participants are supposed to be semi-quantum, i.e., they can only control single photons. Finally, two potential methods to design post-confirmation mechanism are presented in this restricted scenario.

  3. Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

    Science.gov (United States)

    Zhong, Ming; Liu, Yi-Tao; Liu, Xiao-Ying; Shi, Fu-Kuan; Zhang, Li-Qin; Zhu, Mei-Fang; Xie, Xu-Ming

    2016-06-28

    Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined. It is found that the mechanical properties of the PAA hydrogels are significantly influenced by the contents of covalent cross-linkers, Fe(3+) ions and water, which can be adjusted within a substantial range and thus broaden the applications of the hydrogels. Meanwhile, the PAA hydrogels have excellent recoverability based on the dynamic and reversible ionic cross-linking enabled by Fe(3+) ions. Moreover, the swelling capacity of the PAA hydrogels is as high as 1800 times in deionized water due to the synergistic effects of ionic and covalent cross-linkings. The combination of balanced mechanical properties, efficient recoverability, high swelling capacity and facile preparation provides a new method to obtain high-performance hydrogels.

  4. Mechanical behavior of ultra-fine grained and nanocrystalline metals and single crystals: Experiments, modeling and simulations

    Science.gov (United States)

    Liu, Jian

    Ultra-fine grained (ufg, 100 nm viscoplastic phenomenological Khan--Liang--Farrokh (KLF) model is used to correlate the experimental results of the ufg/nc Ti. Crystal Plasticity Finite Element Method (CPFEM) with three different single crystal plasticity constitutive models is used for the purpose of incorporating strain rate and temperature effects into CPFEM. The classical and two newly developed single crystal plasticity models are used to simulate the deformation responses of single crystal aluminum. A constitutive model based on intragranular dislocation slip is shown to correlate closely to the stain rate effect and latent hardening behavior of single crystal Al. For ufg/nc face-centered cubic (FCC) material, we assume that dislocation slip is still the most important deformation mechanism while there is no interaction between dislocations within grains. We develop a constitutive model based on dislocation glide within ufg/nc grains and include all stages of dislocation activities especially their interactions with GB. An Arrhenius type rate is established based on the thermal activated depinning of dislocations from GB obstacles. The thermal strength is obtained as a function of the activation energy of the GB obstacles and the activation length. The athermal part includes the strength due to the grain size dependence and the strength due to the dislocation density. The model parameters for two ufg/nc materials are determined by comparing experimental results to the one dimensional (1D) flow stress model using a Taylor's factor. The new constitutive model is incorporated into three dimensional crystal plasticity and the crystal plasticity model is implemented into a UMAT subroutine of ABAQUS finite element program. The uniaxial deformation responses of two ufg/nc materials are simulated using the previously determined model parameters. CPFEM simulations give flow stress predictions that are very close to 1D model correlations/predictions. It is a clear

  5. Preparation and applications of mechanically exfoliated single-layer and multilayer MoS₂ and WSe₂ nanosheets.

    Science.gov (United States)

    Li, Hai; Wu, Jumiati; Yin, Zongyou; Zhang, Hua

    2014-04-15

    Although great progress has been achieved in the study of graphene, the small current ON/OFF ratio in graphene-based field-effect transistors (FETs) limits its application in the fields of conventional transistors or logic circuits for low-power electronic switching. Recently, layered transition metal dichalcogenide (TMD) materials, especially MoS2, have attracted increasing attention. In contrast to its bulk material with an indirect band gap, a single-layer (1L) MoS2 nanosheet is a semiconductor with a direct band gap of ~1.8 eV, which makes it a promising candidate for optoelectronic applications due to the enhancement of photoluminescence and high current ON/OFF ratio. Compared with TMD nanosheets prepared by chemical vapor deposition and liquid exfoliation, mechanically exfoliated ones possess pristine, clean, and high-quality structures, which are suitable for the fundamental study and potential applications based on their intrinsic thickness-dependent properties. In this Account, we summarize our recent research on the preparation, characterization, and applications of 1L and multilayer MoS2 and WSe2 nanosheets produced by mechanical exfoliation. During the preparation of nanosheets, we proposed a simple optical identification method to distinguish 1L and multilayer MoS2 and WSe2 nanosheets on a Si substrate coated with 90 and 300 nm SiO2. In addition, we used Raman spectroscopy to characterize mechanically exfoliated 1L and multilayer WSe2 nanosheets. For the first time, a new Raman peak at 308 cm(-1) was observed in the spectra of WSe2 nanosheets except for the 1L WSe2 nanosheet. Importantly, we found that the 1L WSe2 nanosheet is very sensitive to the laser power during characterization. The high power laser-induced local oxidation of WSe2 nanosheets and single crystals was monitored by Raman spectroscopy and atomic force microscopy (AFM). Hexagonal and monoclinic structured WO3 thin films were obtained from the local oxidization of single- to triple

  6. Dying piece by piece: carbohydrate dynamics in aspen (Populus tremuloides) seedlings under severe carbon stress.

    Science.gov (United States)

    Wiley, Erin; Hoch, Günter; Landhäusser, Simon M

    2017-11-02

    Carbon starvation as a mechanism of tree mortality is poorly understood. We exposed seedlings of aspen (Populus tremuloides) to complete darkness at 20 or 28 °C to identify minimum non-structural carbohydrate (NSC) concentrations at which trees die and to see if these levels vary between organs or with environmental conditions. We also first grew seedlings under different shade levels to determine if size affects survival time under darkness due to changes in initial NSC concentration and pool size and/or respiration rates. Darkness treatments caused a gradual dieback of tissues. Even after half the stem had died, substantial starch reserves were still present in the roots (1.3-3% dry weight), indicating limitations to carbohydrate remobilization and/or transport during starvation in the absence of water stress. Survival time decreased with increased temperature and with increasing initial shade level, which was associated with smaller biomass, higher respiration rates, and initially smaller NSC pool size. Dead tissues generally contained no starch, but sugar concentrations were substantially above zero and differed between organs (~2% in stems up to ~7.5% in leaves) and, at times, between temperature treatments and initial, pre-darkness shade treatments. Minimum root NSC concentrations were difficult to determine because dead roots quickly began to decompose, but we identify 5-6% sugar as a potential threshold for living roots. This variability may complicate efforts to identify critical NSC thresholds below which trees starve. © Society for Experimental Biology 2017.

  7. Mechanical properties of nickel-coated single-walled carbon nanotubes and their embedded gold matrix composites

    International Nuclear Information System (INIS)

    Song Haiyang; Zha Xinwei

    2010-01-01

    The effects of nickel coating on the mechanical behaviors of armchair single-walled carbon nanotubes (SWCNTs) and their embedded gold matrix composites under axial tension are investigated using molecular dynamics (MD) simulation method. The results show that the Young's moduli and tensile strength of SWCNTs obviously decrease after nickel coating. For armchair SWCNTs, the decreased ratio of the Young's moduli of SWCNTs with smaller radius is larger than that of SWCNTs with larger radius. A comparison is made between the response to Young's modulus of a composite with parallel embedded nanotube and the response of a composite with vertically embedded nanotube. The results show that the uncoated SWCNT can enhance the Young's modulus of composite under the condition of parallel embedment, but such improvement disappears under the condition of vertical embedment because the interaction between SWCNT and gold matrix is too weak for effective load transfer. However, the nickel-coated SWCNT can indeed significantly improve the composite behavior.

  8. Eight piece quadrupole magnet, method for aligning quadrupole magent pole tips

    Energy Technology Data Exchange (ETDEWEB)

    Jaski, Mark S.; Liu, Jie; Donnelly, Aric T.; Downey, Joshua S.; Nudell, Jeremy J.; Jain, Animesh

    2018-01-30

    The invention provides an alternative to the standard 2-piece or 4-piece quadrupole. For example, an 8-piece and a 10-piece quadrupole are provided whereby the tips of each pole may be adjustable. Also provided is a method for producing a quadrupole using standard machining techniques but which results in a final tolerance accuracy of the resulting construct which is better than that obtained using standard machining techniques.

  9. Copy Number Variations in Amyotrophic Lateral Sclerosis: Piecing the Mosaic Tiles Together through a Systems Biology Approach.

    Science.gov (United States)

    Morello, Giovanna; Guarnaccia, Maria; Spampinato, Antonio Gianmaria; La Cognata, Valentina; D'Agata, Velia; Cavallaro, Sebastiano

    2018-02-01

    Amyotrophic lateral sclerosis (ALS) is a devastating and still untreatable motor neuron disease. Despite the molecular mechanisms underlying ALS pathogenesis that are still far from being understood, several studies have suggested the importance of a genetic contribution in both familial and sporadic forms of the disease. In addition to single-nucleotide polymorphisms (SNPs), which account for only a limited number of ALS cases, a consistent number of common and rare copy number variations (CNVs) have been associated to ALS. Most of the CNV-based association studies use a traditional candidate-gene approach that is inadequate for uncovering the genetic architectures of complex traits like ALS. The emergent paradigm of "systems biology" may offer a new perspective to better interpret the wide spectrum of CNVs in ALS, enabling the characterization of the complex network of gene products underlying ALS pathogenesis. In this review, we will explore the landscape of CNVs in ALS, putting specific emphasis on the functional impact of common CNV regions and genes consistently associated with increased risk of developing disease. In addition, we will discuss the potential contribution of multiple rare CNVs in ALS pathogenesis, focusing our attention on the complex mechanisms by which these proteins might impact, individually or in combination, the genetic susceptibility of ALS. The comprehensive detection and functional characterization of common and rare candidate risk CNVs in ALS susceptibility may bring new pieces into the intricate mosaic of ALS pathogenesis, providing interesting and important implications for a more precise molecular biomarker-assisted diagnosis and more effective and personalized treatments.

  10. Single Session of Functional Electrical Stimulation-Assisted Walking Produces Corticomotor Symmetry Changes Related to Changes in Poststroke Walking Mechanics.

    Science.gov (United States)

    Palmer, Jacqueline A; Hsiao, HaoYuan; Wright, Tamara; Binder-Macleod, Stuart A

    2017-05-01

    Recent research demonstrated that the symmetry of corticomotor drive with the paretic and nonparetic plantarflexor muscles was related to the biomechanical ankle moment strategy that people with chronic stroke used to achieve their greatest walking speeds. Rehabilitation strategies that promote corticomotor balance might improve poststroke walking mechanics and enhance functional ambulation. The study objectives were to test the effectiveness of a single session of gait training using functional electrical stimulation (FES) to improve plantarflexor corticomotor symmetry and plantarflexion ankle moment symmetry and to determine whether changes in corticomotor symmetry were related to changes in ankle moment symmetry within the session. This was a repeated-measures crossover study. On separate days, 20 people with chronic stroke completed a session of treadmill walking either with or without the use of FES of their ankle dorsi- and plantarflexor muscles. We calculated plantarflexor corticomotor symmetry using transcranial magnetic stimulation and plantarflexion ankle moment symmetry during walking between the paretic and the nonparetic limbs before and after each session. We compared changes and tested relationships between corticomotor symmetry and ankle moment symmetry following each session. Following the session with FES, there was an increase in plantarflexor corticomotor symmetry that was related to the observed increase in ankle moment symmetry. In contrast, following the session without FES, there were no changes in corticomotor symmetry or ankle moment symmetry. No stratification was made on the basis of lesion size, location, or clinical severity. These findings demonstrate, for the first time (to our knowledge), the ability of a single session of gait training with FES to induce positive corticomotor plasticity in people in the chronic stage of stroke recovery. They also provide insight into the neurophysiologic mechanisms underlying improvements in

  11. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures.

    Science.gov (United States)

    Shim, Hye Won; Yang, Byoung-Eun

    2015-12-01

    To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos® implants. This was a retrospective clinical study that analyzed 450 single Ankylos® implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all Ptooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.

  12. Single-dose ethanol administration activates the hypothalamic-pituitary-adrenal axis: exploration of the mechanism of action.

    Science.gov (United States)

    Thiagarajan, A B; Mefford, I N; Eskay, R L

    1989-10-01

    Activation of the hypothalamic-pituitary-adrenal axis (HPAA) by single-dose ethanol administration, which achieved moderately high blood ethanol levels, was explored in naive rats in order to determine the mechanism of ethanol's activation of the stress axis. Adult male rats received a single dose (3.2 g/kg body weight-1 of a 12% solution of ethanol in physiological saline. The plasma concentration of immunoreactive (ir) adrenocorticotropic hormone (ACTH), beta-endorphin (BE) and corticosterone (CS) was determined by radioimmunoassay, whereas, plasma concentrations of epinephrine (E) and norepinephrine (NE) were quantified following reverse-phase liquid chromatographic separation and amperometric detection. Ethanol induced maximal plasma ACTH levels within minutes, which declined toward basal levels by 60 min, whereas, plasma concentration of CS rose rapidly and remained elevated at 60 min. Plasma ACTH and CS levels in saline-treated control animals did not vary significantly at any time point. Consistent with co-release of ACTH from corticotrophs, the plasma concentration of ir-BE increased 5-fold at 15 min and declined towards basal levels at 60 min after-ethanol challenge. Plasma E increased 10- to 20-fold as compared to saline controls or preinjection levels and returned to preinjection levels by 90 min, in a manner similar to ethanol-induced changes in proopiomelanocortin-derived peptides and CS. Removal of the adrenal medulla and thus the source of E prior to ethanol administration, did not attenuate activation of the HPAA. Passive immunoneutralization of arginine vasopressin (AVP), using a high-titer AVP antiserum and a protocol which was found to block ether-induced ACTH secretion by 40% in adult male rats, failed to even partially block ethanol-induced ACTH or CS secretion. The results of this study indicate that neither adrenal medulla-derived E nor AVP are significant regulators or coregulators of corticotroph secretions following a moderately high

  13. Growth, structural, optical, mechanical and quantum chemical analysis of unidirectional grown bis(guanidinium) 5-sulfosalicylate (BGSSA) single crystal

    Science.gov (United States)

    Sreedevi, R.; Saravana Kumar, G.; Amarsingh Bhabu, K.; Balu, T.; Murugakoothan, P.; Rajasekaran, T. R.

    2018-02-01

    Bis(guanidinium) 5-sulfosalicylate single crystal was grown by using Sankaranarayanan-Ramasamy (SR) method from the solution of methanol and water in equimolar ratio. Good quality crystal with 50 mm length and 10 mm in diameter was grown. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm the crystal structure and it was found to be orthorhombic. UV-Vis-NIR spectroscopic study revealed that the SR method grown crystal had good optical transparency with wide optical band gap of 4.4 eV. The presence of the functional groups and modes of vibrations were identified by FTIR spectroscopy recorded in the range 4000-400 cm-1. The mechanical strength of the grown crystal was confirmed using Vickers microhardness tester by applying load from 25 g to 100 g. Density functional theory (DFT) method with B3LYP/6-31-G (d,p) level basis set was employed and hence the optimized molecular geometry, first order hyperpolarizability, dipole moment, thermodynamic functions, molecular electrostatic potential and frontier molecular orbital analysis of the grown BGSSA sample was computed and analysed.

  14. Molecular dynamics study on the evolution of interfacial dislocation network and mechanical properties of Ni-based single crystal superalloys

    Science.gov (United States)

    Li, Nan-Lin; Wu, Wen-Ping; Nie, Kai

    2018-05-01

    The evolution of misfit dislocation network at γ /γ‧ phase interface and tensile mechanical properties of Ni-based single crystal superalloys at various temperatures and strain rates are studied by using molecular dynamics (MD) simulations. From the simulations, it is found that with the increase of loading, the dislocation network effectively inhibits dislocations emitted in the γ matrix cutting into the γ‧ phase and absorbs the matrix dislocations to strengthen itself which increases the stability of structure. Under the influence of the temperature, the initial mosaic structure of dislocation network gradually becomes irregular, and the initial misfit stress and the elastic modulus slowly decline as temperature increasing. On the other hand, with the increase of the strain rate, it almost has no effect on the elastic modulus and the way of evolution of dislocation network, but contributes to the increases of the yield stress and tensile strength. Moreover, tension-compression asymmetry of Ni-based single crystal superalloys is also presented based on MD simulations.

  15. Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

    Science.gov (United States)

    Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

    2018-04-01

    Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

  16. Electro-opto-mechanical radio-frequency oscillator driven by guided acoustic waves in standard single-mode fiber

    Directory of Open Access Journals (Sweden)

    Yosef London

    2017-04-01

    Full Text Available An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified, and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics.

  17. Prospective Comparison of One-Piece and Three-Piece Tecnis Aspheric Intraocular Lenses: 1-year Stability and its Effect on Visual Function.

    Science.gov (United States)

    Miyata, Kazunori; Kataoka, Yasushi; Matsunaga, Jiro; Honbo, Masato; Minami, Keiichiro

    2015-09-01

    To compare the stability and visual function of one-piece hydrophobic intraocular lens (IOL) (ZCB00, Abbot Medical Optics) and a three-piece hydrophobic IOL (ZA9003, Abbot Medical Optics) after cataract surgery. Eighteen eyes of 18 patients with the one-piece IOL and 20 eyes of 20 patients with the three-piece IOL who underwent cataract surgery were evaluated prospectively on best corrected distance visual acuity, postoperative refractive error, IOL decentration and tilt, anterior chamber depth (ACD), spherical aberration and contrast sensitivity. Measurements were performed 1 week and 1, 3, 6 and 12 months postoperatively. The postoperative outcomes were compared between the two groups. In the one-piece group, a hyperopic refractive error (p piece group. There were no significant differences in BCVA, IOL tilt, spherical aberration or contrast sensitivity. The stability of the one-piece IOL was greater than that of the three-piece IOL. The postoperative ACD and refractive error demonstrated that an anteriorly offset haptic in the one-piece IOL allowed incremental fixation to the posterior capsule.

  18. Dual mode fuel injector with one piece needle valve member

    Science.gov (United States)

    Lawrence, Keith E.; Hinrichsen, Michael H.; Buckman, Colby

    2005-01-18

    A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set controlled respectively by inner and outer needle value members. The homogenous charged nozzle outlet set is defined by an outer needle value member that is moveably positioned in an injector body, which defines the conventional nozzle outlet set. The inner needle valve member is positioned in the outer needle valve member. The outer needle valve member is a piece component that includes at least one external guide surface, an external value surface and an internal valve seat.

  19. Electrification: Connecting the Pieces in the Broader View

    Energy Technology Data Exchange (ETDEWEB)

    Gearhart, Chris C [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-28

    Presented at the SELECT Annual Meeting on September 26, 2017, this PowerPoint presentation gives an overview of connectivity and automation and how these new technologies will impact society in both known and unknown ways. Electrification challenges and opportunities are also outlined as without electrification, connectivity and automation will just magnify the negative health, climate and economic problems of the current transportation systems. Electrification can provide benefits while mitigating the negative consequences. And with careful connection of all of the pieces from materials up through controls, a sustainable transportation eco-system is attainable.

  20. Introduction to solid mechanics an integrated approach

    CERN Document Server

    Lubliner, Jacob

    2014-01-01

    This textbook presents for the first time in one text the concepts and processes covered in statics and mechanics of materials curricula following a systematic, topically integrated approach. Since the turn of the millennium, it has become common in engineering schools to combine the traditional undergraduate offerings in rigid-body statics (usually called “statics”) and deformable body mechanics (known traditionally as “strength of materials” or, more recently, “mechanics of materials”) into a single, introductory course in solid mechanics. Many textbooks for the new course sequentially meld pieces of existing, discrete books—sometimes, but not always, acknowledging the origin—into two halves covering Statics and Mechanics of Materials. In this volume, Professors Lubliner and Papadopoulos methodically combine the essentials of statics and mechanics of materials, illustrating the relationship of concepts throughout, into one "integrated" text. This book also: ·         Offers thorough...

  1. Acute effects of single and multiple level thoracic manipulations on chronic mechanical neck pain: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Puntumetakul R

    2015-01-01

    Full Text Available Rungthip Puntumetakul,1,2 Thavatchai Suvarnnato,1,3 Phurichaya Werasirirat,1 Sureeporn Uthaikhup,2 Junichiro Yamauchi,4,5 Rose Boucaut6 1School of Physical Therapy, Faculty of Associated Medical Sciences, 2Research Center in Back, Neck, Other Joint Pain and Human Performance, 3Physical Therapy Unit, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 4Graduate School of Human Health Sciences, Tokyo Metropolitan University, 5Future Institute for Sport Sciences, Tokyo, Japan; 6School of Health Sciences (Physiotherapy, University of South Australia, Adelaide, SA, Australia Background: Thoracic spine manipulation has become a popular alternative to local cervical manipulative therapy for mechanical neck pain. This study investigated the acute effects of single-level and multiple-level thoracic manipulations on chronic mechanical neck pain (CMNP.Methods: Forty-eight patients with CMNP were randomly allocated to single-level thoracic manipulation (STM at T6–T7 or multiple-level thoracic manipulation (MTM, or to a control group (prone lying. Cervical range of motion (CROM, visual analog scale (VAS, and the Thai version of the Neck Disability Index (NDI-TH scores were measured at baseline, and at 24-hour and at 1-week follow-up.Results: At 24-hour and 1-week follow-up, neck disability and pain levels were significantly (P<0.05 improved in the STM and MTM groups compared with the control group. CROM in flexion and left lateral flexion were increased significantly (P<0.05 in the STM group when compared with the control group at 1-week follow-up. The CROM in right rotation was increased significantly after MTM compared to the control group (P<0.05 at 24-hour follow-up. There were no statistically significant differences in neck disability, pain level at rest, and CROM between the STM and MTM groups.Conclusion: These results suggest that both single-level and multiple-level thoracic manipulation improve neck disability

  2. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

    2013-12-26

    Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

  3. Effects of specimen size and yttria concentration on mechanical properties of single crystalline yttria-stabilized tetragonal zirconia nanopillars

    Science.gov (United States)

    Zhang, Ning; Asle Zaeem, Mohsen

    2017-07-01

    The nanoscale plastic deformation of yttria-stabilized tetragonal zirconia (YSTZ) is highly dependent on the crystallographic orientations, i.e., dislocation is induced when the loading direction is 45° tilted to {111} and {101} slip planes, while tetragonal to monoclinic phase transformation dominates the plastic deformation when loading direction is perpendicular to the slip planes. This study investigates the effects of specimen size and yttria concentration on the mechanical response of single crystalline YSTZ nanopillars. Through uniaxial compression test, the smaller-is-stronger phenomenon is revealed in nanopillars deformed through a dislocation motion mechanism. Serrated stacking faults are observed in the smallest nanopillar, while neat primary slip plane forms in the largest nanopillar. In contrast, the larger-is-stronger relation is observed in nanopillars in which deformation is mediated by tetragonal to monoclinic phase transformation. It is noted that the ratio of transformed monoclinic phase to the remaining tetragonal phase is the highest in the smallest nanopillar. The strength of nanopillars is identified to decrease by increasing the amount of yttria due to the creation of more oxygen vacancies that act as weak points to facilitate dislocation motion and accelerate phase transformation.

  4. A Modified Model Reference Adaptive Control for a Single Motor of Latch Type Control Element Drive Mechanism

    International Nuclear Information System (INIS)

    Park, Bae Jeong

    2016-01-01

    A modified Model Reference Adaptive Control (MRAC) for a single motor of latch type Control Element Drive Mechanism (CEDM) is described herein. The CEDM has complicated dynamic characteristics including electrical, mechanical, and magnetic effects. The previous control system has utilized a Proportional-Integral (PI) controller, and the control performance is limited according to nonlinear dynamic characteristics and environmental conditions. The modified MRAC using system identification (ID) technique improves the control performance in the operating condition such as model parameter variation and environmental condition change. The modified MRAC using the identified reference model with feed-forward gain and 180Hz noise reduction filter presents better performance under normal and/or abnormal condition. The simplified reference model can make H/W implementation more practical on the viewpoint of less computation and good performance. Actually, the CEDM controller shall be capable of controlling 101 control element assemblies (CEAs) individually in the nuclear power plant. Because the load conditions and the environmental condition around the 101 CEAs are all different minutely, the proposed modified MRAC can be a good practice. The modified MRAC controller will be applied in the real nuclear power plant later and this will overcome some weak point of PI controller

  5. Enhancement of the thermal and mechanical properties of polyurethane/polyvinyl chloride blend by loading single walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    A.M. Hezma

    2017-06-01

    Full Text Available Structural, thermal, and mechanical properties of pure blend and nanocomposites based on polyurethane (PU and polyvinyl chloride (PVC doped with low different content of single walled-carbon nanotubes (SWCNTs were studied. The nanocomposites at different concentration were prepared via casting technique. The interaction between PU/PVC and CNTs were examined via FT-IR studies. The changes in the structures of the nanocomposites were examined using X- Ray Diffraction (XRD, and the results indicated that the amorphous domains of nanocomposites increased with increasing SWCNTs content. Transmission electron microscope (TEM observation indicated that SWCNTs surface was wrapped with the polymer with the thermal properties of nanocomposites improved. The mechanical behavior of the nanocomposites was evaluated as a function of SWCNTs content. The main enhancement in tensile properties was observed, e.g., the tensile strength and elastic modulus increased compared with the pure blend, which may be attributed to the interaction and adhesion between CNTs and the polymer matrices due to the hydrogen bonding between carbonyl groups (C=O of polymer blend chains and carboxylic acid (COOH groups of CNTs.

  6. In vitro performance of two-piece zirconia implant systems for anterior application.

    Science.gov (United States)

    Preis, Verena; Kammermeier, Armin; Handel, Gerhard; Rosentritt, Martin

    2016-06-01

    To investigate the influence of the implant-abutment connection on the long-term in vitro performance and fracture resistance of two-piece zirconia implant systems for anterior application. Six groups of two-piece zirconia implant systems (n=10/group) with screw-retained (5×) or bonded (1×) connections were restored with full-contour zirconia crowns. A two-piece screw-retained titanium system served as reference. For simulating anterior loading the specimens (n=8/group) were mounted at an angle of 135° in the chewing simulator, and subjected to thermal cycling (TC: 2×9000×5°/55°C) and mechanical loading (ML: 3.6×10(6)×100N). Failed restorations were examined (scanning electron microscopy). Fracture resistance and maximum bending stress of surviving restorations were determined. 2 specimens per group were loaded to fracture after 24h water storage without TCML. Data were statistically analyzed (ANOVA; Bonferroni; Kaplan-Meier-Log-Rank; α=0.05). The bonded zirconia system and the titanium reference survived TCML without any failures. Screw-retained zirconia systems showed fractures of abutments and/or implants, partly combined with screw fracture/loosening. Failure frequency (F) varied between the groups (F=8×: 3 groups, F=3×: 1 group, F=1×: 1 group). The Log-Rank-test showed significant (p=0.000) differences. Fracture forces and maximum bending stresses (mean±standard deviation) differed significantly ( p=0.000) between 233.4±31.4N/317.1±42.6N/mm(2) and 404.3±15.1N/549.2±20.5N/mm(2). Fracture forces after TCML were similar to 24h fracture forces. Screw-retained two-piece zirconia implant systems showed higher failure rates and lower fracture resistance than a screw-retained titanium system, and may be appropriate for clinical anterior requirements with limitations. Failures involved the abutment/implant region around the screw, indicating that the connecting design is crucial for clinical success. Copyright © 2016 Academy of Dental Materials

  7. Development of an in vivo visual robot system with a magnetic anchoring mechanism and a lens cleaning mechanism for laparoendoscopic single-site surgery (LESS).

    Science.gov (United States)

    Feng, Haibo; Dong, Dinghui; Ma, Tengfei; Zhuang, Jinlei; Fu, Yili; Lv, Yi; Li, Liyi

    2017-12-01

    Surgical robot systems which can significantly improve surgical procedures have been widely used in laparoendoscopic single-site surgery (LESS). For a relative complex surgical procedure, the development of an in vivo visual robot system for LESS can effectively improve the visualization for surgical robot systems. In this work, an in vivo visual robot system with a new mechanism for LESS was investigated. A finite element method (FEM) analysis was carried out to ensure the safety of the in vivo visual robot during the movement, which was the most important concern for surgical purposes. A master-slave control strategy was adopted, in which the control model was established by off-line experiments. The in vivo visual robot system was verified by using a phantom box. The experiment results show that the robot system can successfully realize the expected functionalities and meet the demands of LESS. The experiment results indicate that the in vivo visual robot with high manipulability has great potential in clinical application. Copyright © 2017 John Wiley & Sons, Ltd.

  8. Cooling profile following prosthetic preparation of 1-piece dental implants.

    Science.gov (United States)

    Cohen, Omer; Gabay, Eran; Machtei, Eli E

    2010-01-01

    The aim of this study was to evaluate the effect of water irrigation on heat dissipation kinetics following abutment preparation of 1-piece dental implants. UNO 1-piece dental implants were mounted on Plexiglas apparatus clamping the implant at the collar. T-type thermocouple was attached to the first thread of the implant and recorded thermal changes at 100 millisecond intervals. Implants were prepared using highspeed dental turbine at 400,000 RPM with a coarse diamond bur. Once temperature reached 47 degrees C, abutment preparation was discontinued. Thirty implants were divided into 2 groups. Group A: Passive cooling without water irrigation. Group B: Cooling with turbine's water spray adjacent to the implant (30 mL/min). The following parameters were measured: T47 (time from peak temperature to 47 degrees C), T50%, T75% (time until the temperature amplitude decayed by 50% and 75%, respectively), dTemp50%/dt decay, and dTemp75%/dt decay (cooling rate measured at 50% and 75% of amplitude decay, respectively). Water spray irrigation significantly reduced T47 (1.37+/-0.29 seconds vs 19.97+/-3.06 seconds, Pspray irrigation also increased cooling capacity ninefold: dTemp50%/dt decay (4.14+/-0.61 degrees C/s vs 0.48+/-0.06 degrees C/s, Pspray adjacent to the abutment following the cessation of implant preparation might prove beneficial for rapid cooling of the implant.

  9. Scleral Fixation of a One-Piece Toric Intraocular lens

    Science.gov (United States)

    Emanuel, Matthew E.; Randleman, J. Bradley; Masket, Samuel

    2013-01-01

    Purpose To describe a novel technique for toric intraocular lens (IOL) repositioning and fixation in the absence of adequate capsular support Methods Case report and literature review Results Two cases are presented with scleral fixation of a one-piece toric IOL (SN6AT series, Alcon Inc.) In both cases, toric IOLs initially placed within the capsular bag became decentered due to poor capsular support and/or posterior capsule rupture. To avoid the potential complications of lens explantation and maintain the astigmatic benefits of the toric IOL, scleral fixation of the lenses was performed. The Hoffman technique was used to create reverse scleral pockets without conjunctival dissection. A 10-0 suture was used to capture and then secure the lens haptics in a lasso-type fashion. Sutures were then buried within the previously created scleral pockets. Both patients had well centered lenses postoperatively and have remained stable at last follow-up, up to thirty months postoperatively. Conclusion In the absence of adequate capsular support, scleral fixation is a viable option for one-piece toric IOL fixation to avoid IOL explanation PMID:23380416

  10. Relating mechanical properties and chemical bonding in an inorganic-organic framework material: a single-crystal nanoindentation study.

    Science.gov (United States)

    Tan, Jin Chong; Furman, Joshua D; Cheetham, Anthony K

    2009-10-14

    We report the application of nanoindentation and atomic force microscopy to establish the fundamental relationships between mechanical properties and chemical bonding in a dense inorganic-organic framework material: Ce(C(2)O(4))(HCO(2)), 1. Compound 1 is a mixed-ligand 3-D hybrid which crystallizes in an orthorhombic space group, in which its three basic building blocks, i.e. the inorganic metal-oxygen-metal (M-O-M) chains and the two organic bridging ligands, (oxalate and formate) are all oriented perpendicular to one another. This unique architecture enabled us to decouple the elastic and plastic mechanical responses along the three primary axes of a single crystal to understand the contribution associated with stiff vs compliant basic building blocks. The (001)-oriented facet that features rigid oxalate ligands down the c-axis exhibits the highest stiffness and hardness (E approximately 78 GPa and H approximately 4.6 GPa). In contrast, the (010)-oriented facet was found to be the most compliant and soft (E approximately 43 GPa and H approximately 3.9 GPa), since the formate ligand, which is the more compliant building block within this framework, constitutes the primary linkages down the b-axis. Notably, intermediate stiffness and hardness (E approximately 52 GPa and H approximately 4.1 GPa) were measured on the (100)-oriented planes. This can be attributed to the Ce-O-Ce chains that zigzag down the a-axis (Ce...Ce metal centers form an angle of approximately 132 degrees) and also the fact that the 9-coordinated CeO(9) polyhedra are expected to be geometrically more compliant. Our results present the first conclusive evidence that the crystal orientation dominated by inorganic chains is not necessarily more robust from the mechanical properties standpoint. Rigid organic bridging ligands (such as oxalate), on the other hand, can be used to produce greater stiffness and hardness properties in a chosen crystallographic orientation. This study demonstrates that

  11. Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation

    Science.gov (United States)

    Boulicault, Jean E.; Alves, Sandra; Cole, Richard B.

    2016-08-01

    MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe3+ > Al3+ > Li+ > Ga3+ > Co2+ > Cr3+ > Cu2+ > [Mn2+, Mg2+] > [Na+, K+]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.

  12. Prospective, multicenter, single-arm study of mechanical thrombectomy using Solitaire Flow Restoration in acute ischemic stroke.

    Science.gov (United States)

    Pereira, Vitor M; Gralla, Jan; Davalos, Antoni; Bonafé, Alain; Castaño, Carlos; Chapot, René; Liebeskind, David S; Nogueira, Raul G; Arnold, Marcel; Sztajzel, Roman; Liebig, Thomas; Goyal, Mayank; Besselmann, Michael; Moreno, Antonio; Moreno, Alfredo; Schroth, Gerhard

    2013-10-01

    Mechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire Flow Restoration in patients with acute ischemic stroke. Solitaire Flow Restoration Thrombectomy for Acute Revascularization was an international, multicenter, prospective, single-arm study of Solitaire Flow Restoration thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary end point was the revascularization rate (thrombolysis in cerebral infarction ≥2b) of the occluded vessel as determined by an independent core laboratory. The secondary end point was the rate of good functional outcome (defined as 90-day modified Rankin scale, 0-2). A total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada, and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, and the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and procedure-related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic. In this single-arm study, treatment with the Solitaire Flow Restoration device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days. http://www.clinicaltrials.gov. Unique identifier: NCT01327989.

  13. Two-piece zirconia implants supporting all-ceramic crowns: a prospective clinical study.

    Science.gov (United States)

    Cionca, Norbert; Müller, Nada; Mombelli, Andrea

    2015-04-01

    The aim of this prospective clinical study is to evaluate the safety and efficacy of a new all-ceramic implant system to replace missing teeth in partially edentulous patients. Thirty-two partially edentulous, systemically healthy patients were treated with 49 two-piece zirconia implants (ZERAMEX(®) T Implant System). Zirconia abutments were connected with adhesive resin cement. Single-unit full-ceramic crowns were cemented. The cases have been followed for 588 ± 174 days after loading (range 369-889 days). All patients have been re-evaluated 1 year after loading. The cumulative survival rate 1 year after loading was 87% implants. All failures were the result of aseptic loosening, and no implants were lost after the first year. The results of the other cases were good, and the patients were very satisfied. The cumulative soft tissue complication rate was 0%, the cumulative technical complication rate was 4% implants, the cumulative complication rate for bone loss >2 mm was 0%, and the cumulative esthetic complication rate was 0%. Including the data from 20 patients treated with an earlier version of the system, an over-all 2-year cumulative survival rate of 86% was calculated for a total of 76 two-piece zirconia implants supporting all-ceramic crowns in 52 patients. Replacement of single teeth in the posterior area was possible with this new full-ceramic implant system. Failures were due to aseptic loosening. © 2014 The Authors. Clinical Oral Implants Research Published by John Wiley & Sons Ltd.

  14. Two-piece zirconia implants supporting all-ceramic crowns: A prospective clinical study

    Science.gov (United States)

    Cionca, Norbert; Müller, Nada; Mombelli, Andrea

    2015-01-01

    Objectives The aim of this prospective clinical study is to evaluate the safety and efficacy of a new all-ceramic implant system to replace missing teeth in partially edentulous patients. Material and methods Thirty-two partially edentulous, systemically healthy patients were treated with 49 two-piece zirconia implants (ZERAMEX® T Implant System). Zirconia abutments were connected with adhesive resin cement. Single-unit full-ceramic crowns were cemented. The cases have been followed for 588±174 days after loading (range 369–889 days). All patients have been re-evaluated 1 year after loading. Results The cumulative survival rate 1 year after loading was 87% implants. All failures were the result of aseptic loosening, and no implants were lost after the first year. The results of the other cases were good, and the patients were very satisfied. The cumulative soft tissue complication rate was 0%, the cumulative technical complication rate was 4% implants, the cumulative complication rate for bone loss >2 mm was 0%, and the cumulative esthetic complication rate was 0%. Including the data from 20 patients treated with an earlier version of the system, an over-all 2-year cumulative survival rate of 86% was calculated for a total of 76 two-piece zirconia implants supporting all-ceramic crowns in 52 patients. Conclusions Replacement of single teeth in the posterior area was possible with this new full-ceramic implant system. Failures were due to aseptic loosening. PMID:24666352

  15. Mechanical impedance of the sitting human body in single-axis compared to multi-axis whole-body vibration exposure.

    Science.gov (United States)

    Holmlund, P; Lundström, R

    2001-01-01

    The study was aimed to investigate the mechanical impedance of the sitting human body and to compare data obtained in laboratory single-axis investigations with multi-axis data from in vehicle measurements. The experiments were performed in a laboratory for single-axis measurements. The multi-axis exposure was generated with an eight-seat minibus where the rear seats had been replaced with a rigid one. The subjects in the multi-axis experiment all participated in the single-axis experiments. There are quite a few investigations in the literature describing the human response to single-axis exposure. The response from the human body can be expected to be affected by multi-axis input in a different way than from a single-axis exposure. The present knowledge of the effect of multiple axis exposure is very limited. The measurements were performed using a specially designed force and accelerometer plate. This plate was placed between the subject and the hard seat. Outcome shows a clear difference between mechanical impedance for multi-axis exposure compared to single-axis. This is especially clear in the x-direction where the difference is very large. The conclusion is that it seems unlikely that single-axis mechanical impedance data can be directly transferred to a multi-axis environment. This is due to the force cross-talk between different directions.

  16. Physiological effects of a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates.

    Science.gov (United States)

    Mehta, Y; Shetye, J; Nanavati, R; Mehta, A

    2016-01-01

    To assess the changes on various physiological cardio-respiratory parameters with a single chest physiotherapy session in mechanically ventilated and extubated preterm neonates with respiratory distress syndrome. This is a prospective observational study in a neonatal intensive care unit setting. Sixty preterm neonates with respiratory distress syndrome, thirty mechanically ventilated and thirty extubated preterm neonates requiring chest physiotherapy were enrolled in the study. Parameters like heart rate (HR), respiratory rate (RR), Silverman Anderson score (SA score in extubated), oxygen saturation (SpO2) and auscultation findings were noted just before, immediately after chest physiotherapy but before suctioning, immediately after suctioning and after 5 minutes of the session. The mean age of neonates was 9.55±5.86 days and mean birth weight was 1550±511.5 g. As there was no significant difference in the change in parameters on intergroup comparison, further analysis was done considering two groups together (n = 60) except for SA score. As SA score was measured only in extubated neonates. HR did not change significantly during chest physiotherapy compared to the baseline but significantly decreased after 15 minutes (p = 0.01). RR and SA score significantly increased after suctioning (p = 0.014) but reduced after 15 minutes (p = physiotherapy (p = physiotherapy may help facilitate the overall well-being of a fragile preterm neonate. Lung auscultation finding suggests that after suctioning, there was a significant reduction in crepitation (p = 0.0000) but significant increase in crepitation after 15 minutes (p = physiotherapy. Chest physiotherapy is safe in preterm neonates. Suctioning causes significant cardio-respiratory parameter changes, but within normal physiological range. Thus, chest physiotherapy should be performed with continuous monitoring only when indicated and not as a routine procedure. More research is needed

  17. The mechanism of the nitric oxide-mediated enhancement of tert-butylhydroperoxide-induced DNA single strand breakage

    Science.gov (United States)

    Guidarelli, Andrea; Clementi, Emilio; Sciorati, Clara; Cantoni, Orazio

    1998-01-01

    Caffeine (Cf) enhances the DNA cleavage induced by tert-butylhydroperoxide (tB-OOH) in U937 cells via a mechanism involving Ca2+-dependent mitochondrial formation of DNA-damaging species (Guidarelli et al., 1997b). Nitric oxide (NO) is not involved in this process since U937 cells do not express the constitutive nitric oxide synthase (cNOS).Treatment with the NO donors S-nitroso-N-acetyl-penicillamine (SNAP, 10 μM), or S-nitrosoglutathione (GSNO, 300 μM), however, potentiated the DNA strand scission induced by 200 μM tB-OOH. The DNA lesions generated by tB-OOH alone, or combined with SNAP, were repaired with superimposable kinetics and were insensitive to anti-oxidants and peroxynitrite scavengers but suppressed by iron chelators.SNAP or GSNO did not cause mitochondrial Ca2+ accumulation but their enhancing effects on the tB-OOH-induced DNA strand scission were prevented by ruthenium red, an inhibitor of the calcium uniporter of mitochondria. Furthermore, the enhancing effects of both SNAP and GSNO were identical to and not additive with those promoted by the Ca2+-mobilizing agents Cf or ATP.The SNAP- or GSNO-mediated enhancement of the tB-OOH-induced DNA cleavage was abolished by the respiratory chain inhibitors rotenone and myxothiazol and was not apparent in respiration-deficient cells.It is concluded that, in cells which do not express the enzyme cNOS, exogenous NO enhances the accumulation of DNA single strand breaks induced by tB-OOH via a mechanism involving inhibition of complex III. PMID:9846647

  18. Different diffusion mechanisms of oxygen in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vovk, R.V.; Boiko, Y.I.; Bogdanov, V.V.; Kamchatnaya, S.N.; Goulatis, I.L. [V. N. Karazin Kharkiv National University, 4 Svobody sq., 61077 Kharkiv (Ukraine); Chroneos, A. [Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry CV1 5FB (United Kingdom); Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    2017-05-15

    Highlights: • Single file diffusion mechanism of oxygen ions. • Ho modifies the diffusion mechanism in the oxygen sublattice. • Ho changes the efficient interaction of ions in CuO-planes. - Abstract: In the present study, the time dependencies of the resistivity of ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re=Y, Ho) single crystals with varying degree of deviation from oxygen stoichiometry was investigated. It was shown that the accelerated transport of oxygen ions in the initial stage of the process can be carried out along the one-dimensional non-stoichiometric vacancies’ accumulation by the single file diffusion mechanism. The final phase redistribution of oxygen ions in ReBa{sub 2}Cu{sub 3}O{sub 7−x} (Re = Y, Ho) is described by the classical mechanism of volume diffusion. The substitution of yttrium by holmium significantly affects the charge redistribution and changes the efficient interaction of ions in CuO-planes, thereby modifying the mass transfer diffusion mechanisms in the oxygen sublattice. Thus, a significant length change of the time intervals occurs, corresponding to the oxygen ions’ single file and volume diffusion mechanisms.

  19. Effectiveness of one-piece implants inserted in cuspid sites.

    Science.gov (United States)

    Carinci, Francesco

    2012-12-01

    One-piece implants (OPIs) incorporate the trans-mucosal abutment facing the soft tissues as an integral part of the implant. OPIs are usually welded together and loaded immediately. Since no report focuses specifically on OPIs inserted in cuspid sites, a retrospective study is performed. Nineteen patients (10 females and 9 males) with a median age of 62 years (range, 43-80) were admitted at the Dental Clinic, University of Chieti (Italy), for evaluation and implant treatment, by one surgeon between January and December 2010. In our series, the survival rate (SVR) and success rate (SCR) were 96.8% and 100%, respectively. Statistical analysis demonstrated that no studied variable had an impact on the survival (i.e., lost implants) and clinical success (i.e., crestal bone resorption). OPIs are reliable devices for oral rehabilitation in the cuspid sites.

  20. Cutting insert and work piece materials for minimum quantity lubrication

    Science.gov (United States)

    Kurgin, Sheri; Barber, Gary; Zou, Qian

    2011-05-01

    There is considerable interest in utilizing either dry or minimum quantity lubrication (MQL) as an alternative to flood cooling due to environmental concerns with flood coolant such as excessive misting and disposal of the used coolant. Dry machining can result in high tool wear and also built up edge problems on the cutting tool. The objective of this research was to study the effect of work piece material and tool material on the machining characteristics, in this case reaming, of aluminum using MQL. In particular, a high tin casting and three different tool materials: carbide, DLC and PCD were studied. The high tin casting was found to produce lower cutting temperature and lower spindle power. The PCD coated insert performed the best in terms of lowest temperature rise, lowest spindle power and highest part quality.

  1. The RNA silencing pathway: the bits and pieces that matter.

    Directory of Open Access Journals (Sweden)

    Marian A C Groenenboom

    2005-07-01

    Full Text Available Cellular pathways are generally proposed on the basis of available experimental knowledge. The proposed pathways, however, may be inadequate to describe the phenomena they are supposed to explain. For instance, by means of concise mathematical models we are able to reveal shortcomings in the current description of the pathway of RNA silencing. The silencing pathway operates by cleaving siRNAs from dsRNA. siRNAs can associate with RISC, leading to the degradation of the target mRNA. We propose and analyze a few small extensions to the pathway: a siRNA degrading RNase, primed amplification of aberrant RNA pieces, and cooperation between aberrant RNA to trigger amplification. These extensions allow for a consistent explanation for various types of silencing phenomena, such as virus induced silencing, transgene and transposon induced silencing, and avoidance of self-reactivity, as well as for differences found between species groups.

  2. Effect of Low Angle Grain Boundaries on Mechanical Properties of DD5 Single Crystal Ni-base Superalloy

    Directory of Open Access Journals (Sweden)

    QIN Jianchao

    2017-06-01

    Full Text Available The effects of low angle grain boundaries on the mechanical properties of second generation single crystal superalloy DD5 were investigated and the test specimens were prepared by using seeds. The results show that at 870 ℃, the yield strength and breaking strength showed no difference when the angle is below 16.1°. The elongation is higher than 15% when the angle is below 11.4°, but the elongation decreases quickly when angle is above 11.4°. At 980 ℃/250 MPa, the rupture life is higher than 130 h when the angle is below 5.1°, and decreased slowly when the angle is above 5.1°. The rupture life still remaines 85% when the angle is 14.8°. But the rupture life decreases quickly when the angle is above 14.8°.At 1093 ℃/158 MPa, the rupture life is higher than 30 h when the angle is below 5.1°, and decreases when the angle is above 5.1°.

  3. Atomic mechanism for the growth of wafer-scale single-crystal graphene: theoretical perspective and scanning tunneling microscopy investigations

    Science.gov (United States)

    Niu, Tianchao; Zhang, Jialin; Chen, Wei

    2017-12-01

    Chemical vapor deposition (CVD) is the most promising approach for producing low-cost, high-quality, and large area graphene. Revealing the graphene growth mechanism at the atomic-scale is of great importance for realizing single crystal graphene (SCG) over wafer scale. Density functional theoretical (DFT) calculations are playing an increasingly important role in revealing the structure of the most stable carbon species, understanding the evolution processes, and disclosing the active sites. Scanning tunneling microscopy (STM) is a powerful surface characterization tool to illustrate the real space distribution and atomic structures of growth intermediates during the CVD process. Combining them together can provide valuable information to improve the atomically controlled growth of SCG. Starting from a basic concept of the substrate effect on realizing SCG, this review covers the progress made in theoretical investigations on various carbon species during graphene growth on different transition metal substrates, in the STM study of the structural intermediates on transition metal surfaces, and in synthesizing graphene nanoribbons with atomic-precise width and edge structure, ending with a perspective on the future development of 2D materials beyond graphene.

  4. A First-Principle Theoretical Study of Mechanical and Electronic Properties in Graphene Single-Walled Carbon Nanotube Junctions

    Directory of Open Access Journals (Sweden)

    Ning Yang

    2017-11-01

    Full Text Available The new three-dimensional structure that the graphene connected with SWCNTs (G-CNTs, Graphene Single-Walled Carbon Nanotubes can solve graphene and CNTs′ problems. A comprehensive study of the mechanical and electrical performance of the junctions was performed by first-principles theory. There were eight types of junctions that were constituted by armchair and zigzag graphene and (3,3, (4,0, (4,4, and (6,0 CNTs. First, the junction strength was investigated. Generally, the binding energy of armchair G-CNTs was stronger than that of zigzag G-CNTs, and it was the biggest in the armchair G-CNTs (6,0. Likewise, the electrical performance of armchair G-CNTs was better than that of zigzag G-CNTs. Charge density distribution of G-CNTs (6,0 was the most homogeneous. Next, the impact factors of the electronic properties of armchair G-CNTs were investigated. We suggest that the band gap is increased with the length of CNTs, and its value should be dependent on the combined effect of both the graphene’s width and the CNTs’ length. Last, the relationship between voltage and current (U/I were studied. The U/I curve of armchair G-CNTs (6,0 possessed a good linearity and symmetry. These discoveries will contribute to the design and production of G-CNT-based devices.

  5. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

    Science.gov (United States)

    Villegas, Irene F.; Palardy, Genevieve

    2016-01-01

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints. PMID:26890931

  6. Mechanical properties of Bi,Pb(2223) single filaments and Ic(ε) behaviour in longitudinally strained tapes

    International Nuclear Information System (INIS)

    Passerini, Reynald; Dhalle, Marc; Seeber, Bernd; Fluekiger, Rene

    2002-01-01

    The Young's modulus and fracture stress of isolated Bi,Pb(2223) filaments were deduced from three-point bending tests performed at different stages of the tapes preparation. These results were introduced in the model describing the evolution of critical current of tapes submitted to a longitudinal strain in view to predict their irreversible strain limit ε irr . These calculated irreversible strain limits were compared to measured values, taken from a set of tapes made with different filling factors and composite matrices. This experiment shows that the predicted irreversible strain limits correspond to the measured ones. Presenting the I c behaviour of highly stressed tapes in a magnetic field, we discuss the evolution of the ratio I strong c0 /I c0 versus strain. This value, representative of the fraction of the critical current attributed to strongly connected grains, increases significantly during the crack formation regime at ε > ε irr . This indicates that mechanically weak links correspond to electromagnetically weak ones. This result is further confirmed by comparing the modulus of rupture obtained in single filaments extracted from tapes with different I c values

  7. Concomitant mitral valve surgery with aortic valve replacement: a 21-year experience with a single mechanical prosthesis

    Directory of Open Access Journals (Sweden)

    Sidhu Pushpinder

    2007-05-01

    Full Text Available Abstract Background Long-term survival for combined aortic and mitral valve replacement appears to be determined by the mitral valve prosthesis from our previous studies. This 21-year retrospective study assess long-term outcome and durability of aortic valve replacement (AVR with either concomitant mitral valve replacement (MVR or mitral valve repair (MVrep. We consider only a single mechanical prosthesis. Methods Three hundred and sixteen patients underwent double valve replacement (DVR (n = 273 or AVR+MVrep (n = 43, in the period 1977 to 1997. Follow up of 100% was achieved via telephone questionnaire and review of patients' medical records. Actuarial analysis of long-term survival was determined by Kaplan-Meier method. The Cox regression model was used to evaluate potential predictors of mortality. Results There were seventeen cases (5.4% of early mortality and ninety-six cases of late mortality. Fifteen-year survival was similar in both groups at 44% and 57% for DVR and AVR+MVrep respectively. There were no significant differences in valve related deaths, anticoagulation related complications, or prosthetic valve endocarditis between the groups. There were 6 cases of periprosthetic leak in the DVR group. Sex, pre-operative mitral and aortic valve pathology or previous cardiac surgery did not significantly affect outcome. Conclusion The mitral valve appears to be the determinant of survival following double valve surgery and survival is not significantly influenced by mitral valve repair.

  8. Dispersion of single-wall carbon nanotubes with supramolecular Congo red - properties of the complexes and mechanism of the interaction.

    Science.gov (United States)

    Jagusiak, Anna; Piekarska, Barbara; Pańczyk, Tomasz; Jemioła-Rzemińska, Małgorzata; Bielańska, Elżbieta; Stopa, Barbara; Zemanek, Grzegorz; Rybarska, Janina; Roterman, Irena; Konieczny, Leszek

    2017-01-01

    A method of dispersion of single-wall carbon nanotubes (SWNTs) in aqueous media using Congo red (CR) is proposed. Nanotubes covered with CR constitute the high capacity system that provides the possibility of binding and targeted delivery of different drugs, which can intercalate into the supramolecular, ribbon-like CR structure. The study revealed the presence of strong interactions between CR and the surface of SWNTs. The aim of the study was to explain the mechanism of this interaction. The interaction of CR and carbon nanotubes was studied using spectral analysis of the SWNT-CR complex, dynamic light scattering (DLS), differential scanning calorimetry (DSC) and microscopic methods: atomic force microscopy (AFM), transmission (TEM), scanning (SEM) and optical microscopy. The results indicate that the binding of supramolecular CR structures to the surface of the nanotubes is based on the "face to face stacking". CR molecules attached directly to the surface of the nanotubes can bind further, parallel-oriented molecules and form supramolecular and protruding structures. This explains the high CR binding capacity of carbon nanotubes. The presented system - containing SWNTs covered with CR - offers a wide range of biomedical applications.

  9. Resolving the Aerosol Piece of the Global Climate Picture

    Science.gov (United States)

    Kahn, R. A.

    2017-12-01

    Factors affecting our ability to calculate climate forcing and estimate model predictive skill include direct radiative effects of aerosols and their indirect effects on clouds. Several decades of Earth-observing satellite observations have produced a global aerosol column-amount (AOD) record, but an aerosol microphysical property record required for climate and many air quality applications is lacking. Surface-based photometers offer qualitative aerosol-type classification, and several space-based instruments map aerosol air-mass types under favorable conditions. However, aerosol hygroscopicity, mass extinction efficiency (MEE), and quantitative light absorption, must be obtained from in situ measurements. Completing the aerosol piece of the climate picture requires three elements: (1) continuing global AOD and qualitative type mapping from space-based, multi-angle imagers and aerosol vertical distribution from near-source stereo imaging and downwind lidar, (2) systematic, quantitative in situ observations of particle properties unobtainable from space, and (3) continuing transport modeling to connect observations to sources, and extrapolate limited sampling in space and time. At present, the biggest challenges to producing the needed aerosol data record are: filling gaps in particle property observations, maintaining global observing capabilities, and putting the pieces together. Obtaining the PDFs of key particle properties, adequately sampled, is now the leading observational deficiency. One simplifying factor is that, for a given aerosol source and season, aerosol amounts often vary, but particle properties tend to be repeatable. SAM-CAAM (Systematic Aircraft Measurements to Characterize Aerosol Air Masses), a modest aircraft payload deployed frequently could fill this gap, adding value to the entire satellite data record, improving aerosol property assumptions in retrieval algorithms, and providing MEEs to translate between remote-sensing optical constraints

  10. Corrosion mineralogy of an 1800 Spanish piece of eight

    International Nuclear Information System (INIS)

    Craig, J.R.; Callahan, J.E.; Kimbell, J.T.; Solberg, T.N.

    2002-01-01

    Spanish colonial eight real silver coins, commonly called Pieces of Eight, were used throughout the Spanish-speaking world for hundreds of years. We undertook a detailed mineralogical, textural, and chemical investigation of an 1800 Carlos IIII eight real coin recovered from the wreck of the Spanish frigate Santa Leocadia, which sank on the rocky shore of Ecuador on November 16, 1800, with a loss of more than 140 lives and of 2,100,000 pesos of gold and silver coins. The coin is a typical eight real piece, composed of about 90% Ag and 10% Cu. It was buried in elastic sediments beneath the oxidized zone, such that it reacted with sulfur released by sulfate-reducing bacteria. Consequently, the coin has been totally encapsulated in a mixture of sand, gravel, and shell fragments cemented by metal sulfides. The residual coin consists of silver with small interspersed micrometric grains of copper. Reaction of the dissolved metal with the bacterially generated diagenetic sulfur in the intergranular fluids resulted in extensive cementation of the sediment particles by Ag and Cu sulfides. In the 1-mm zone immediately adjacent to the coin, Cu-bearing acanthite occurs as concentric layers with intervening zones of sand and clay. Beyond this zone, acanthite formed from Ag dissolved from the coin occurs as a more or less continuous interstitial cement with local small islands of covellite, CuS. Copper also occurs as films of Cu carbonate on quartz grains, as isolated grains of jalpaite Ag 3 CuS 2 , stromeyerite AgCuS, mckinstryite (Ag,Cu) 2 S, and as atacamite Cu 2 C1(OH) 3 , which rim and replace detrital carbonate grains. (author)

  11. The Role of Proteases in Hippocampal Synaptic Plasticity: Putting Together Small Pieces of a Complex Puzzle.

    Science.gov (United States)

    Salazar, Ivan L; Caldeira, Margarida V; Curcio, Michele; Duarte, Carlos B

    2016-02-01

    Long-term synaptic plasticity in the hippocampus is thought to underlie the formation of certain forms of memory, including spatial memory. The early phase of long-term synaptic potentiation and synaptic depression depends on post-translational modifications of synaptic proteins, while protein synthesis is also required for the late-phase of both forms of synaptic plasticity (L-LTP and L-LTD). Numerous pieces of evidence show a role for different types of proteases in synaptic plasticity, further increasing the diversity of mechanisms involved in the regulation of the intracellular and extracellular protein content. The cleavage of extracellular proteins is coupled to changes in postsynaptic intracellular mechanisms, and additional alterations in this compartment result from the protease-mediated targeting of intracellular proteins. Both mechanisms contribute to initiate signaling cascades that drive downstream pathways coupled to synaptic plasticity. In this review we summarize the evidence pointing to a role for extracellular and intracellular proteases, with distinct specificities, in synaptic plasticity. Where in the cells the proteases are located, and how they are regulated is also discussed. The combined actions of proteases and translation mechanisms contribute to a tight control of the synaptic proteome relevant for long-term synaptic potentiation and synaptic depression in the hippocampus. Additional studies are required to elucidate the mechanisms whereby these changes in the synaptic proteome are related with plasticity phenomena.

  12. Mechanism

    Directory of Open Access Journals (Sweden)

    Yao Yu

    2010-01-01

    Full Text Available The kinematics analysis method of a novel 3-DOF wind tunnel mechanism based on cable-driven parallel mechanism is provided. Rodrigues' parameters are applied to express the transformation matrix of the wire-driven mechanism in the paper. The analytical forward kinematics model is described as three quadratic equations using three Rodridgues' parameters based on the fundamental theory of parallel mechanism. Elimination method is used to remove two of the variables, so that an eighth-order polynomial with one variable is derived. From the equation, the eight sets of Rodridgues' parameters and corresponding Euler angles for the forward kinematical problem can be obtained. In the end, numerical example of both forward and inverse kinematics is included to demonstrate the presented forward-kinematics solution method. The numerical results show that the method for the position analysis of this mechanism is effective.

  13. Influence of the Cutting Conditions in the Surface Finishing of Turned Pieces of Titanium Alloys

    Science.gov (United States)

    Huerta, M.; Arroyo, P.; Sánchez Carrilero, M.; Álvarez, M.; Salguero, J.; Marcos, M.

    2009-11-01

    Titanium is a material that, despite its high cost, is increasingly being introduced in the aerospace industry due to both, its weight, its mechanical properties and its corrosion potential, very close to that of carbon fiber based composite material. This fact allows using Ti to form Fiber Metal Laminates Machining operations are usually used in the manufacturing processes of Ti based aerospace structural elements. These elements must be machined under high surface finish requirements. Previous works have shown the relationship between the surface roughness and the tool changes in the first instants of turning processes. From these results, new tests have been performed in an aeronautical factory, in order to analyse roughness in final pieces.

  14. UTILIZATION OF STEREOLOGY FOR QUANTITATIVE ANALYSIS OF PLASTIC DEFORMATION OF FORMING PIECES

    Directory of Open Access Journals (Sweden)

    Maroš Martinkovič

    2012-01-01

    Full Text Available Mechanical working leads to final properties of forming pieces, which are affected by conditions of production technology. Utilization of stereology leads to the detail analysis of three-dimensional plastic deformed material structure by different forming technologies, e.g. forging, extruding, upsetting, metal spinning, drawing etc. The microstructure of cold drawing wires was analyzed. Grain boundaries orientation was measured on the parallel section of wire with a different degree of deformation and direct axis plastic deformation was evaluated in bulk formed part. The strain of probes on their sections was obtained using stereology by measurement of degree of grain boundary orientation which was converted to deformation using model of conversion of grain boundary orientation degree to deformation.

  15. Dynamical analysis of periodic bursting in piece-wise linear planar neuron model.

    Science.gov (United States)

    Ji, Ying; Zhang, Xiaofang; Liang, Minjie; Hua, Tingting; Wang, Yawei

    2015-12-01

    A piece-wise linear planar neuron model, namely, two-dimensional McKean model with periodic drive is investigated in this paper. Periodical bursting phenomenon can be observed in the numerical simulations. By assuming the formal solutions associated with different intervals of this non-autonomous system and introducing the generalized Jacobian matrix at the non-smooth boundaries, the bifurcation mechanism for the bursting solution induced by the slowly varying periodic drive is presented. It is shown that, the discontinuous Hopf bifurcation occurring at the non-smooth boundaries, i.e., the bifurcation taking place at the thresholds of the stimulation, leads the alternation between the rest state and spiking state. That is, different oscillation modes of this non-autonomous system convert periodically due to the non-smoothness of the vector field and the slow variation of the periodic drive as well.

  16. Rapid identification of the quality decoction pieces by partial least squares -based pattern recognition: grade classification of the decoction pieces of Saposhnikovia divaricata.

    Science.gov (United States)

    Liu, Ying; Li, Li; Xiao, Yongqing; Yao, Jiaqi; Li, Pengyuan; Chen, Liang; Yu, Dingrong; Ma, Yinlian

    2016-08-01

    Herbal medicines are commonly used in many countries after they undergo processing. Quality decoction pieces are a guarantee of the efficacy and safety of the herbal medical products. Here, a strategy based on chemical analysis combined with chemometric techniques was proposed for the classification and prediction of the different grades of the decoction pieces. Considering the necessity for a shared and simple method for the grade classification for the public, in this paper, the characterization of the chemical constituents was determined by utilizing high-performance liquid chromatography (HPLC)/diode array detection. HPLC was first established for the characterization of the chemical constituents of the different grade decoction pieces. Furthermore, a simultaneous quantification of several of the marker compounds in these decoction pieces was obtained. Finally, a partial least squares-based pattern recognition method was utilized to obtain a predictive model for the grade classification of the decoction pieces. Saposhnikovia divaricata (Turcz.) Schischk was used as a case study. The partial least squares -based pattern recognition for the grade classification of the decoction pieces of S. divaricata demonstrated good sensitivity, specificity and prediction performance, which may efficiently validate the identification results of appearance assessment. The proposed strategy is expected to provide a new insight for the grade classification and quality control of the decoction pieces. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Growth, mechanical, and magnetic study of SmFeO{sub 3} single crystal grown by optical floating zone technique

    Energy Technology Data Exchange (ETDEWEB)

    Babu, P. Ramesh [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhaumik, Indranil [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India); Ganesamoorthy, S. [Material Science Group, IGCAR, Kalpakkam, Tamil Nadu (India); Kalainathan, S., E-mail: kalainathan@yahoo.com [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhatt, R.; Karnal, A.K.; Gupta, P.K. [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India)

    2016-08-15

    Single crystals of Samarium orthoferrite (SmFeO{sub 3}) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T{sub SR} = 480 K) and the other is AFM to paramagnetic transitions (T{sub N} = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO{sub 3} crystals. Bloch parameter (3.28 × 10{sup −5} K{sup −3/2}) has also been evaluated. - Highlights: • SmFeO{sub 3} single crystals have been grown by OFZ technique in air. • The microhardness has been found to decreases non-linearly with the applied load. • At 472 K, spin reorientation occurs in Fe sublattice. • The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state. • Bloch 3/2-law holds good for SmFeO{sub 3} (B-parameter as 3.28 × 10{sup −5} K{sup −3/2}).

  18. Evaluation of induced defetcs in AISI 304 a steel test pieces using conventional and non conventional ultrasonic inspection methods

    International Nuclear Information System (INIS)

    Rodriguez Prato, Edda C

    2006-01-01

    The use of patterns of reference in the evaluation of pieces by non destructive methods, particularly with ultrasonic techniques, is indispensable because the features of this pattern's defects can be correlated with those found in pieces that are in service. In the industry, stainless steels, particularly Type 340 austenitic steels, are widely used in some systems for their excellent mechanical properties in corrosive mediums. But these same pieces may have discontinuities and defects in the welded regions, that occur mainly during production and installation and are also due to subsequent operating conditions. Volumetric inspection techniques reveal the integrity of a material in its thickness and detect internal discontinuities that are not visible on the surface of the piece. Conventional and non conventional ultrasonic techniques are used most often now and among the non conventional techniques is Ultrasonic Spectroscopy [1-2]. Ultrasonic spectroscopy aims to determine the dependence of the properties and characteristics of the material under study with the frequency. These may be geometric in origin (thickness of layers, size, shape and direction of the discontinuity) or inherent (attenuation, dispersion, absorption). The dependence of the frequency is usually connected to some microscopic geometric properties, such as the grain size in polycrystalline materials. In the characterization and detection of discontinuities, the frequency spectrum of an ultrasonic pulse contains information about the shape, size and direction of a discontinuity [1-3]. Therefore, the ultrasonic spectral analysis is very important for the characterization of materials and contributes to the study and evaluation of the ultrasonic signals [4-6]. This study evaluates the behavior of the ultrasonic signals obtained from patterns of welded pieces of AISI 304 stainless steel by using conventional and non conventional methods of ultrasonic inspection. Welded test pieces of AISI 304

  19. Retrospective multicenter analysis of immediate provisionalization using one-piece narrow-diameter (3.0-mm) implants.

    Science.gov (United States)

    Sohn, Dong-Seok; Bae, Min-Su; Heo, Jeong-Uk; Park, Jun-Sub; Yea, Sun-Hae; Romanos, Georgios E

    2011-01-01

    The aim of this retrospective analysis was to report on the clinical outcome of immediate provisionalization using one-piece narrow-diameter implants. The dental records of patients who received narrow implants were reviewed. Narrow-diameter (3.0-mm) one-piece implants were used to support restorations of missing maxillary lateral incisors and mandibular incisors. All implants were placed in a one-stage procedure according to the protocol recommended by the manufacturer, with immediate placement of provisional restorations. Following an average healing period of 3 months in the mandible and 5 months in the maxilla, the definitive prostheses were fabricated. The survival rate of the implants was analyzed, and radiographic evaluation was performed. RESULTS. Thirty-six patients (20 men and 16 women), aged from 42 to 72 years (average age of 53 years), were treated with 62 one-piece narrow implants. A success rate of 100% was observed over a period up to 33 months (mean, 23 ± 4.3 months). Among these, 8 implants were placed in maxillary lateral incisor positions and 54 implants were placed in mandibular incisor areas. Forty-four implants supported fixed partial prostheses, and 18 implants supported single crowns. The majority of the implants were 15 mm in length. Mean marginal bone loss at the 12-month follow-up visit was 0.53 ± 0.37 mm (range, 0 to 1.4 mm). The results obtained in this retrospective analysis suggest that the one-piece narrow-diameter implant can predictably restore missing maxillary lateral incisors and mandibular incisor with narrow interdental spaces and labiolingual widths.

  20. Stress-induced formation mechanism of stacking fault tetrahedra in nano-cutting of single crystal copper

    International Nuclear Information System (INIS)

    Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Guo, Yongbo; Xie, Wenkun

    2015-01-01

    Graphical abstract: In this paper, molecular dynamics simulation is performed to study the distribution of dislocation defects and local atomic crystal structure of single crystal copper. The stress distribution is investigated which is calculated by virial stress and analyzed by static pressure. The results are shown in (a)–(d). It is indicated that the compressive stress mainly spreads over the shear-slip zone, and the tensile stress is consisted in flank friction zone, shown in (a). The high tensile stress in subsurface is the source of stress, shown in (b). By the driven action of the stress source, the initial stair-rod dislocation nucleates. Then the dislocation climbs along four {1 1 1} planes under the stress driven action, shown in (d). Finally, the SFT is formed by the interaction of the compressive stress and the tensile stress which come from the shear-slip zone and friction zone, respectively. Besides, stair-rod dislocation, stacking faults and dislocation loop are also nucleated in the subsurface, shown in (c). Dislocation distribution, local atomic crystal structure state and stress-induced formation process of SFT by atomic. - Highlights: • A novel defect structure “stress-induced stacking fault tetrahedra” is revealed. • Atomic structural evolution and stress state distribution of the SFT are studied. • The stress-induced formation mechanism of the SFT is proposed. - Abstract: Stacking fault tetrahedra commonly existed in subsurface of deformed face center cubic metals, has great influence on machining precision and surface roughness in nano-cutting. Here we report, a stacking fault tetrahedra is formed in subsurface of workpiece during nano-cutting. The variation of cutting force and subsurface defects distribution are studied by using molecular dynamics simulation. The stress distribution is investigated which is calculated by virial stress and analyzed by static compression. The result shows that the cutting force has a rapidly

  1. [Preliminary study on standardization of production and processing of Angelicae Sinensis Radix pieces].

    Science.gov (United States)

    Nie, Rui-Jie; Wang, Ying-Zi; Sun, Zhen-Yang; Wang, Si-Yu; Zhang, Jing-Zhen

    2017-12-01

    Study on the standardization of Chinese materia medica is an important action for modernization and globalization for traditional Chinese medicine. Standardization on the processing of Chinese herbal pieces is an important part in the study on standardization of Chinese materia medica, so it is of great significance to establish the technical processing standards of Angelicae Sinensis Radix pieces for improving its quality. In this study, single factor experiment was designed to optimize the softening, cutting and drying processes of Angelicae Sinensis Radix. With ferulic acid, Angelicae Sinensis Radix polysaccharide, volatile oil and extracts (water and ethanol) content as the quality index, the effects of different softening, cutting and drying processes on the contents of the five components in Angelicae Sinensis Radix were analyzed, and the normalized distance evaluation method was used to analyze the experimental data. The results showed that the content of five components in Angelicae Sinensis Radix was affected by different softening methods and drying temperature, but the thickness of slice had little effect on the content. The best preparation process for Angelicae Sinensis Radix was as follows: Non-medicinal parts were removed; mildewed and rot as well as moth-eaten parts were removed; washed by the flowing drinking water; stacked in the drug pool; moistening method was used for softening, where 125 mL water was sprayed for every 1 kg of herbs every 2.5 h; upper part of herbs covered with clean and moist cotton, and cut into thin slices (1-2 mm) after 15 h moistening until appropriate softness, with disk thickness of 1-2 cm, then received blast drying for 6 h at 55 ℃, and turned over for 2 times during the drying. Copyright© by the Chinese Pharmaceutical Association.

  2. Unintentional variation in positive end expiratory pressure during resuscitation with a T-piece resuscitator.

    Science.gov (United States)

    Finer, Neil N; Rich, Wade D

    2011-06-01

    The ability of T-piece resuscitators to deliver consistent peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP) during real and simulated neonatal resuscitation has been well described. The Neopuff (Fisher & Paykel Healthcare, Auckland, New Zealand) has been the device used for nearly all of these comparisons. All high risk resuscitations were carried out in our dedicated resuscitation room, and were recorded on video tape for quality assurance purposes.(1) In addition to the audio and video recording, physiologic signals and resuscitation parameters, including oxygen saturation, pulse rate, airway pressure, FiO(2), and others signals as appropriate were also captured. These recordings were reviewed on a biweekly basis as part of a continuing quality review process. Resuscitations were graded for standard of care and the resuscitation checklist was reviewed to determine if the team had any unresolved issues that needed to be addressed. In the year between April of 2009 and March 2010, a period when we fully reviewed approximately 120 videos, we recognized visually obvious PEEP changes on 8 different occasions in ELBW infants. Our target PEEP was 5 cm H20. We observed rapid changes in the PEEP to as high as 15 cm H20 during resuscitation. Based on our single-center experience, a T-piece resuscitation device which has the adjustment for the PEEP level and the orifice which is occluded to deliver a breath in the same location has the potential to cause an inadvertent and potentially toxic increase of PEEP which might not be noticed by the operator. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. Immediate occlusal loading of one-piece zirconia implants: five-year radiographic and clinical evaluation.

    Science.gov (United States)

    Grassi, Felice Roberto; Capogreco, Mario; Consonni, Dario; Bilardi, Germano; Buti, Jacopo; Kalemaj, Zamira

    2015-01-01

    To evaluate radiographic and clinical outcomes of immediate occlusally loaded one-piece zirconia implants after 5 years of follow-up. This longitudinal clinical investigation included patients older than 18 years, in need of implant-supported single-unit dental rehabilitations. One-piece zirconia in healed and postextraction sites and immediately restored with provisional crowns in light occlusal contact. Definitive zirconia-ceramic restorations were delivered 3 to 4 months after surgery. Primary estimated outcomes were implant survival and success. Periapical radiographs were taken at implant insertion (T0), after 1 year (T1), and after 5 years (T2) to assess marginal bone loss (MBL). Probing depth (PD), modified Bleeding Index (mBI), modified Plaque Index (mPI), and gingival recession (REC) were also measured repeatedly for implants and reference teeth. Changes in parameters over time were assessed using the Wilcoxon signed rank test. In addition, multilevel mixed effects linear and logistic regression models were fitted to take into account within-subject correlations and baseline values. Thirty-two implants were inserted in postextraction and healed sites (n = 16 of each) in 17 patients. One immediate implant was lost after 3 months, and one patient with one implant dropped out after T1. Therefore, the cumulative survival rates were 96.9% at T1 and 96.8% at T2 (4.3 to 6 years). No significant differences were observed in mean MBL between immediate and delayed implants at either T1 or T2. Moreover, different baseline parameters (sex, arch, implant location, smoking habits, grafting) did not show any influence on MBL at either time. In general, for all clinical parameters (PD, mBI, mPI, REC), implants seemed to perform similar to if not better than natural teeth. Radiographic and clinical evaluations after 5 years showed satisfactory amounts of MBL and acceptable soft tissue health.

  4. Head-on Allograft Transplantation: A Unique Case Report Where a Large Piece of Femoral Bone was Extruded from One Patient's Body and Impaled Another Patient's Tibia.

    Science.gov (United States)

    Rossman, Stephen R; Shaath, M Kareem; Graf, Kenneth W

    2017-01-01

    Open femoral fractures are relatively uncommon occurrences, with few reports addressing their management. They are caused by high-energy mechanisms, and bone loss is a possible, but infrequent occurrence. We present a case in which two friends, 20- and 21-year-old males, were involved in a motorcycle collision. A large piece of bone was ejected from one patient's femur as a bony projectile and impaled the other patient's tibia, resulting in an open tibial plateau fracture. This is the first case in the English literature, to the best of our knowledge, in which a piece of bone was ejected from one patient, causing a fracture in another. Two males, in their mid-twenties, were involved in a head-on motorcycle collision. Both patients sustained open fractures to their lower extremities. A large piece of bone was ejected from one patient's femur and impaled the other patient's tibia, causing an open tibial plateau fracture. The patient who provided the bony projectile underwent retrograde intramedullary nail fixation. The segmental piece of bone was not replanted, and he went on to heal without negative sequelae at 2-year follow-up. To the best of our knowledge, this is the first case documented in the English literature in which an ejected piece of bone from one person caused a fracture in another fracture. Management of extruded bone segments should be considered on a case-by-case basis.

  5. Exploitation and application of radio-scanning cigarette cartoon lacking pieces online detection system

    International Nuclear Information System (INIS)

    Yang Qicheng; Ma Yunshen; Luo Bing; Chen Yong; Chen Yongfu

    2008-01-01

    Taking Hongta's detecting cigarette cartoon lacking pieces and eliminating it in the course of end-product automatic sorting consignment as an example, this paper introduces detailedly one type of cigarette cartoon lacking pieces online detection system with advantages of original principle, accurate detection, high speed and reliable performance, from the aspects of project design, detection principle, hard-ware configuration, applied technique, running status and etc. Gives one method of detecting and controlling cigarette product lacking pieces for cigarette manufactures. (authors)

  6. Individuality in harpsichord performance: disentangling performer- and piece-specific influences on interpretive choices.

    Science.gov (United States)

    Gingras, Bruno; Asselin, Pierre-Yves; McAdams, Stephen

    2013-01-01

    Although a growing body of research has examined issues related to individuality in music performance, few studies have attempted to quantify markers of individuality that transcend pieces and musical styles. This study aims to identify such meta-markers by discriminating between influences linked to specific pieces or interpretive goals and performer-specific playing styles, using two complementary statistical approaches: linear mixed models (LMMs) to estimate fixed (piece and interpretation) and random (performer) effects, and similarity analyses to compare expressive profiles on a note-by-note basis across pieces and expressive parameters. Twelve professional harpsichordists recorded three pieces representative of the Baroque harpsichord repertoire, including three interpretations of one of these pieces, each emphasizing a different melodic line, on an instrument equipped with a MIDI console. Four expressive parameters were analyzed: articulation, note onset asynchrony, timing, and velocity. LMMs showed that piece-specific influences were much larger for articulation than for other parameters, for which performer-specific effects were predominant, and that piece-specific influences were generally larger than effects associated with interpretive goals. Some performers consistently deviated from the mean values for articulation and velocity across pieces and interpretations, suggesting that global measures of expressivity may in some cases constitute valid markers of artistic individuality. Similarity analyses detected significant associations among the magnitudes of the correlations between the expressive profiles of different performers. These associations were found both when comparing across parameters and within the same piece or interpretation, or on the same parameter and across pieces or interpretations. These findings suggest the existence of expressive meta-strategies that can manifest themselves across pieces, interpretive goals, or expressive devices.

  7. Individuality in harpsichord performance: Disentangling performer- and piece-specific influences on interpretive choices

    Directory of Open Access Journals (Sweden)

    Bruno eGingras

    2013-11-01

    Full Text Available Although a growing body of research has examined issues related to individuality in music performance, few studies have attempted to quantify markers of individuality that transcend pieces and musical styles. This study aims to identify such meta-markers by discriminating between influences linked to specific pieces or interpretive goals and performer-specific playing styles, using two complementary statistical approaches: linear mixed models (LMMs to estimate fixed (piece and interpretation and random (performer effects, and similarity analyses to compare expressive profiles on a note-by-note basis across pieces and expressive parameters. Twelve professional harpsichordists recorded three pieces representative of the Baroque harpsichord repertoire, including three interpretations of one of these pieces, each emphasizing a different melodic line, on an instrument equipped with a MIDI console. Four expressive parameters were analyzed: articulation, note onset asynchrony, timing, and velocity. LMMs showed that piece-specific influences were much larger for articulation than for other parameters, for which performer-specific effects were predominant, and that piece-specific influences were generally larger than effects associated with interpretive goals. Some performers consistently deviated from the mean values for articulation and velocity across pieces and interpretations, suggesting that global measures of expressivity may in some cases constitute valid markers of artistic individuality. Similarity analyses detected significant associations among the magnitudes of the correlations between the expressive profiles of different performers. These associations were found both when comparing across parameters and within the same piece or interpretation, or on the same parameter and across pieces or interpretations. These findings suggest the existence of expressive meta-strategies that can manifest themselves across pieces, interpretive goals, or

  8. The Illocutionary Acts of Luffy's Utterances to His Addressees in Comic One Piece

    OpenAIRE

    Fasril, Adhy Kurnia Putra; Bachtiar, Bachtiar

    2012-01-01

    One aim of this article is to show through a concrete example how illocutionary acts used in One Piece comic. The illustrative example is taken from the utterances of One Piece comic. Central to the analysis proper form of utterances in One Piece comic that contain of illocutionary acts; i.e. representative, directive, commissive, expressive, declarative. 90 utterances were interpreted by actor, and it was found that the use of iilocutionary acts.

  9. Preservation of refrigerated calf meat pieces by ionization

    International Nuclear Information System (INIS)

    Hassouna, M.; Besbes, M.; Ben Hassen, A.; Mahjoub, A.; Maalej, M.

    1998-01-01

    The influence of five 60Co gamma radiation doses in the range of 1 to 5 kGy on chemical composition and bacteriological counts of pieces of calf meat, partially vacuum - packed before treatment, was studied during storage at + 4 degree C up to 28 days. In vivo thermoluminescence dosimetry (TLD) using dosimeters such as lithium fluoride (LiF) was used as a very sensitive procedure to control both dose delivered to the red meat and its degree of uniformity. These two parameters are generally recommended for the quality control of food irradiation process. While ionizing radiation doses of 1 or 2 kGy were unable to increase the shelf life of treated meat, doses of 3, 4 or 5 kGy were very efficient, and adequate to prevent completely the growth of microorganisms indicating faecal contamination such as total coliforms, faecal coliforms and Enterobacteriaceae; they also kept constant the contents of total mesophilic flora and maintained radioresistant psychrotrophic microflora below the value inducing superficial putrefaction of meat (10 7 CFU cntdot g -1 ) at all storage times. Pathogenic germs producing contaminating toxins in foodstuffs such as Salmonella, Staphylococcus aureus and anaerobic sulfite reducing bacteria were totally absent in both control and treated meat. When pieces of meat were irradiated with doses of 3, 4 or 5 kGy, microbial alcalinization and proteolysis revealed by total volatile basic nitrogen were very low during the whole storage period. In addition, total protein did not change as a result of treatment during that period. However, superficial browning and significant variations were observed in water - holding capacity and saturated and unsaturated fatty acids contents in the free fat of treated meat. Ionizing radiation doses had no effect on weight losses and even on the variations of pH after heating of ground calf meat in double boiler at 50, 70 or 90 degree C up to 1 h. However, these modifications very sensitive to cooking temperature

  10. Scanning electron microscope study of polytetrafluoroethylene sliding on aluminum single crystals

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1973-01-01

    Friction experiments were conducted in air with polytetrafluoroethylene (PTFE) sliding on aluminum single crystals. Mechanical scoring of the crystals with (110) and (100) orientations was observed with a single pass of the PTFE slider. No scoring was observed on the (111). The degree of scoring of the crystals is related to the hardness, with the hardest surface (111) showing no damage and the softest surface (110) showing the most severe scoring. Scoring is caused by work-hardened pieces of aluminum which, as a consequence of the adhesion between PTFE and aluminum, were pulled out of the bulk and became embedded in the PTFE polymer.

  11. Effects of stereo-regularity on the single-chain mechanics of polylactic acid and its implications on the physical properties of bulk materials.

    Science.gov (United States)

    Cheng, Bo; Qian, Lu; Qian, Hu-Jun; Lu, Zhong-Yuan; Cui, Shuxun

    2017-10-05

    The material properties of polylactic acid (PLA) are largely determined by its stereo-regularity (tacticity). To find out the origin at the molecular level, the single-chain mechanics of poly-l-lactic acid (PLLA) and poly-d,l-lactide (PDLLA) were comparatively investigated by single-molecule atomic force microscopy (AFM). At a low concentration, PLLA adopted a random-coil conformation in a good solvent. At a high concentration, however, the PLLA chain can be induced into a helix, which consumed additional energy during unfolding by further stretching. Due to the random arrangement of l- and d-repeating units in the PDLLA chain, PDLLA adopts a random-coil conformation at all concentrations. The difference in single-chain mechanics of PLLA and PDLLA at high concentrations may be the cause of their different macroscopic properties. This is the first report to reveal the stereo-regularity-dependent mechanics of a polymer at the single-molecule level, which may help to bridge the gap between understanding single-molecule and materials properties.

  12. [Development and innovation of traditional Chinese medicine processing discipline and Chinese herbal pieces industry].

    Science.gov (United States)

    Xiao, Yong-Qing; Li, Li; Liu, Ying; Ma, Yin-Lian; Yu, Ding-Rong

    2016-01-01

    To elucidate the key issues in the development and innovation of traditional Chinese medicine processing discipline and Chinese herbal pieces industry Chinese herbal pieces industry. According to the author's accumulated experience over years and demand of the development of the Chinese herbal pieces industry, the key issues in the development and innovation on the Chinese herbal pieces industry were summarized. According to the author, the traditional Chinese medicine processing discipline shall focus on a application basis research. The development of this discipline should be closely related to the development of Chinese herbal pieces. The traditional Chinese medicine processing discipline can be improved and its results can be transformed only if this discipline were correlated with the Chinese herbal pieces industry, matched with the development of the Chinese herbal pieces industry, and solved the problems in the development on the Chinese herbal pieces industry. The development of traditional Chinese medicine processing discipline and the Chinese herbal pieces industry also requires scientific researchers to make constant innovations, realize the specialty of the researches, and innovate based on inheritance. Copyright© by the Chinese Pharmaceutical Association.

  13. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  14. Isotherm, thermodynamic, kinetics, and adsorption mechanism studies of Ethidium bromide by single-walled carbon nanotube and carboxylate group functionalized single-walled carbon nanotube.

    Science.gov (United States)

    Moradi, Omid; Fakhri, Ali; Adami, Saeideh; Adami, Sepideh

    2013-04-01

    The studies of kinetics and thermodynamics of adsorption of Ethidium bromide in aqueous solutions on single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by UV-Vis spectroscopy. The adsorption kinetics for SWCNT-COOH and SWCNTs were well described by a intra-particle diffusion model, while Langmuir, Freundlich, Harkins-Jura, and Halsey isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant (K0), standard free energy (ΔG0), standard enthalpy (ΔH0), and standard entropy changes (ΔS0) were measured. The maximum surface coverage for SWCNTs is 36.10% and for SWCNT-COOH is 38.42%. The values of ΔH0 and ΔG0 suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs was endothermic and spontaneous. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Bone response from a dynamic stimulus on a one-piece and multi-piece implant abutment and crown by finite element analysis.

    Science.gov (United States)

    Hajimiragha, Habib; Abolbashari, Mohammadreza; Nokar, Saeed; Abolbashari, AmirHossein; Abolbashari, Mehrdad

    2014-10-01

    The present study was done to evaluate the effects of different types of abutments on the rate and distribution of stress on the bone surrounding the implant by dynamic finite element analysis method. In this study two ITI abutment models-one-piece and multi-piece-along with fixture, bone, and superstructure have been simulated with the help of company-made models. The maximum Von Mises stress (MVMS) was observed in the distobuccal area of the cortical bone near the crest of implant in two implant models. In the multi-piece abutment, MVMS was higher than the one-piece model (27.9 MPa and 23.3 MPa, respectively). Based on the results of this study, it can be concluded that type of abutment influences the stress distribution in the area surrounding the implant during dynamic loading.

  16. Hydrometallurgical Recovery of Metals from Large Printed Circuit Board Pieces

    Science.gov (United States)

    Jadhav, U.; Hocheng, H.

    2015-09-01

    The recovery of precious metals from waste printed circuit boards (PCBs) is an effective recycling process. This paper presents a promising hydrometallurgical process to recover precious metals from waste PCBs. To simplify the metal leaching process, large pieces of PCBs were used instead of a pulverized sample. The chemical coating present on the PCBs was removed by sodium hydroxide (NaOH) treatment prior to the hydrometallurgical treatment. Among the leaching reagents examined, hydrochloric acid (HCl) showed great potential for the recovery of metals. The HCl-mediated leaching of waste PCBs was investigated over a range of conditions. Increasing the acid concentration decreased the time required for complete metal recovery. The shaking speed showed a pronounced positive effect on metal recovery, but the temperature showed an insignificant effect. The results showed that 1 M HCl recovered all of the metals from 4 cm × 4 cm PCBs at room temperature and 150 rpm shaking speed in 22 h.

  17. A One-Piece Lunar Regolith Bag Garage Prototype

    Science.gov (United States)

    Smithers, G. A.; Nehls, M. K.; Hovater, M. A.; Evans, S. W.; Miller, J. S.; Broughton, R. M., Jr.; Beale, D.; Kilinc-Balci, F.

    2007-01-01

    Shelter structures on the moon, even in early phases of exploration, should incorporate lunar materials as much as possible. This Technical Memorandum details the design and construction of a prototype for a one-piece regolith bag unpressurized garage concept and a materials testing program to investigate six candidate fabrics to learn how they might perform in the lunar environment. The conceptualization was that a lightweight fabric form be launched from Earth and landed on the lunar surface to be robotically filled with raw lunar regolith. Regolith bag fabric candidates included: Vectran(TM), Nextel(TM), Gore PTFE Fabric(TM), Zylon(TM), Twaron(TM), and Nomex(TM). Tensile (including post radiation exposure), fold, abrasion, and hypervelocity impact testing were performed under ambient conditions, and also performed under cold and elevated temperatures. In some cases, Johnson Space Center lunar simulant (JSC-1) was used in conjunction with testing. A series of preliminary structures was constructed during final prototype design based on the principles of the classic masonry arch. The prototype was constructed of Kevlar(TM) and filled with vermiculite. The structure is free-standing, but has not yet been load tested. Future plans would be to construct higher fidelity prototypes and to conduct appropriate tests of the structure.

  18. CO oxidation mechanism on the γ-Al{sub 2}O{sub 3} supported single Pt atom: First principle study

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongwei, E-mail: gaohongw369@ms.xjb.ac.cn

    2016-08-30

    Highlights: • DFT studied on CO oxidation mechanism on Pt/γ-Al{sub 2}O{sub 3} catalyst. • DFT studied on the adsorption properties of single Pt on Pt/γ-Al{sub 2}O{sub 3} catalyst. • Pt adsorptions on the Al-terminated surface are more favorable than the ones on the O-terminated surface. • The reactive O*−O−C*=O intermediate mechanism is the dominant reaction pathway for CO oxidation on Pt/γ-Al{sub 2}O{sub 3}. - Abstract: Understanding the role of metal-support interaction for the supported single-atom catalysts is very important in heterogeneous catalysis. Here, Three different CO oxidation mechanisms on Pt/γ-Al{sub 2}O{sub 3} catalyst were probed by periodic density functional theory (DFT) calculations in detail, namely the reactive O*−O−C*=O intermediate mechanism, the reactive CO{sub 3} intermediate mechanism and the Pt-Al{sup 3+} double sites mechanism. According to the calculated results analysis, we concluded that the dominant reaction pathway at the low temperatures is the reactive O*−O−C*=O intermediate mechanism. Our results are in very good agreement with the experimental evidence for O*−O−C*=O coverage on Pt/γ-Al{sub 2}O{sub 3} at room temperature by an in situ diffuse reflectance infrared detector.

  19. T-piece improves arterial and central venous oxygenation in trachestomized patients as compared to continuous positive airway pressure/pressure support ventilation.

    Science.gov (United States)

    Lovas, A; Molnár, Z

    2013-05-01

    T-piece has been widely used as T-piece trial to identify patients who are ready for extubation but it is seldom used as a weaning tool. Our objective was to investigate the effects of breathing via T-piece on gas exchange as compared to continuous positive airway pressure with pressure support (CPAP+PS) and CPAP with automatic tube compensation (CPAP+ATC) as it has not been evaluated yet. Tracheostomized, "ready to be weaned" critically ill patients were enrolled in this prospective, auto-control clinical trial. Arterial oxygen tension (PaO2) was determined on CPAP+PS (t0), 15 minutes later on CPAP+ATC (t1), then on T-piece at 15, 30 and 60 minutes (t2-4). ScvO2 was measured at t0 and t4. Settings of fraction of inspired oxygen (FiO2) and positive end-expiratory pressure (PEEP) were kept constant throughout the investigation. Twenty-five patients were enrolled. T-piece trial was interrupted in 4 cases after t2, due to pulmonary oedema, hypertension or fatigue. PaO2/FiO2 was significantly higher on T-piece (t3,4) then on CPAP (t0,1), P<0.05, PaO2/FiO2 did not change significantly on CPAP+PS (t0) vs. CPAP+ATC (t1) modes: median=208 (interquartile range: 175-266) vs. 223 (186-290) mmHg, P=0.102, but significantly increased from t0-t4: 208 (175-266) vs. 249 (215-325) mmHg, P=0.003, respectively. ScvO2 was significantly higher on T-piece at t4: 80% (75-82%) than on CPAP+PS at t0: 73% (71-78%), P<0.001. On the same FiO2 and PEEP setting, breathing via T-piece improved oxygenation and resulted in increased ScvO2 as compared to breathing on CPAP with PS. Our observations suggest a potential role of T-piece during weaning from mechanical ventilation.

  20. Single-cell mechanics--An experimental-computational method for quantifying the membrane-cytoskeleton elasticity of cells.

    Science.gov (United States)

    Tartibi, M; Liu, Y X; Liu, G-Y; Komvopoulos, K

    2015-11-01

    The membrane-cytoskeleton system plays a major role in cell adhesion, growth, migration, and differentiation. F-actin filaments, cross-linkers, binding proteins that bundle F-actin filaments to form the actin cytoskeleton, and integrins that connect the actin cytoskeleton network to the cell plasma membrane and extracellular matrix are major cytoskeleton constituents. Thus, the cell cytoskeleton is a complex composite that can assume different shapes. Atomic force microscopy (AFM)-based techniques have been used to measure cytoskeleton material properties without much attention to cell shape. A recently developed surface chemical patterning method for long-term single-cell culture was used to seed individual cells on circular patterns. A continuum-based cell model, which uses as input the force-displacement response obtained with a modified AFM setup and relates the membrane-cytoskeleton elastic behavior to the cell geometry, while treating all other subcellular components suspended in the cytoplasmic liquid (gel) as an incompressible fluid, is presented and validated by experimental results. The developed analytical-experimental methodology establishes a framework for quantifying the membrane-cytoskeleton elasticity of live cells. This capability may have immense implications in cell biology, particularly in studies seeking to establish correlations between membrane-cytoskeleton elasticity and cell disease, mortality, differentiation, and migration, and provide insight into cell infiltration through nonwoven fibrous scaffolds. The present method can be further extended to analyze membrane-cytoskeleton viscoelasticity, examine the role of other subcellular components (e.g., nucleus envelope) in cell elasticity, and elucidate the effects of mechanical stimuli on cell differentiation and motility. This is the first study to decouple the membrane-cytoskeleton elasticity from cell stiffness and introduce an effective approach for measuring the elastic modulus. The

  1. Optimization of Process Parameters During End Milling and Prediction of Work Piece Temperature Rise

    Directory of Open Access Journals (Sweden)

    Bhirud N.L.

    2017-09-01

    Full Text Available During the machining processes, heat gets generated as a result of plastic deformation of metal and friction along the tool–chip and tool–work piece interface. In materials having high thermal conductivity, like aluminium alloys, large amount of this heat is absorbed by the work piece. This results in the rise in the temperature of the work piece, which may lead to dimensional inaccuracies, surface damage and deformation. So, it is needed to control rise in the temperature of the work piece. This paper focuses on the measurement, analysis and prediction of work piece temperature rise during the dry end milling operation of Al 6063. The control factors used for experimentation were number of flutes, spindle speed, depth of cut and feed rate. The Taguchi method was employed for the planning of experimentation and L18 orthogonal array was selected. The temperature rise of the work piece was measured with the help of K-type thermocouple embedded in the work piece. Signal to noise (S/N ratio analysis was carried out using the lower-the-better quality characteristics. Depth of cut was identified as the most significant factor affecting the work piece temperature rise, followed by spindle speed. Analysis of variance (ANOVA was employed to find out the significant parameters affecting the work piece temperature rise. ANOVA results were found to be in line with the S/N ratio analysis. Regression analysis was used for developing empirical equation of temperature rise. The temperature rise of the work piece was calculated using the regression equation and was found to be in good agreement with the measured values. Finally, confirmation tests were carried out to verify the results obtained. From the confirmation test it was found that the Taguchi method is an effective method to determine optimised parameters for minimization of work piece temperature.

  2. Translation effects on vertical Bridgman growth and optical, mechanical and surface analysis of 2-phenylphenol single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sadhasivam, S., E-mail: sadha.phy1@gmail.com [Department of Physics, Center for Crystal Growth, SSN College of Engineering, Tamil Nadu, India-603 110 (India); Perumal, Rajesh Narayana

    2016-05-06

    2-phenylphenol optical crystals were grown in cone ampoules using vertical Bridgman technique. Single crystal of 2-phenylphenol with 150 mm length has been grown. The inclination on the conical part of the ampoule reduces the growth defects in the 2-phenylphenol single crystal. The lattice parameters and structure studied using single crystal X-ray diffraction method. 2-phenylphenol single crystal belongs to orthorhombic space group Fdd2. The micro translation rate affects crystal growth of 2-phenylphenol crystal was studied. The translation rate dependent defects present in the crystal were investigated by transmittance, indentation and etching characterizations. The dislocation induced indentation crack lengths variations were studied. Etch pits and striations observed for the selective etchants furnish significant information on growth aspects and degree of defect present in the crystal.

  3. Complex PTSD and phased treatment in refugees: a debate piece

    Directory of Open Access Journals (Sweden)

    F. Jackie June ter Heide

    2016-02-01

    Full Text Available Background: Asylum seekers and refugees have been claimed to be at increased risk of developing complex posttraumatic stress disorder (complex PTSD. Consequently, it has been recommended that refugees be treated with present-centred or phased treatment rather than stand-alone trauma-focused treatment. This recommendation has contributed to a clinical practice of delaying or waiving trauma-focused treatment in refugees with PTSD. Objective: The aim of this debate piece is to defend two theses: (1 that complex trauma leads to complex PTSD in a minority of refugees only and (2 that trauma-focused treatment should be offered to all refugees who seek treatment for PTSD. Methods: The first thesis is defended by comparing data on the prevalence of complex PTSD in refugees to those in other trauma-exposed populations, using studies derived from a systematic review. The second thesis is defended using conclusions of systematic reviews and a meta-analysis of the efficacy of psychotherapeutic treatment in refugees. Results: Research shows that refugees are more likely to meet a regular PTSD diagnosis or no diagnosis than a complex PTSD diagnosis and that prevalence of complex PTSD in refugees is relatively low compared to that in survivors of childhood trauma. Effect sizes for trauma-focused treatment in refugees, especially narrative exposure therapy (NET and culturally adapted cognitive-behaviour therapy (CA-CBT, have consistently been found to be high. Conclusions: Complex PTSD in refugees should not be assumed to be present on the basis of complex traumatic experiences but should be carefully diagnosed using a validated interview. In line with treatment guidelines for PTSD, a course of trauma-focused treatment should be offered to all refugees seeking treatment for PTSD, including asylum seekers.

  4. Byzantine kalophonia, illustrated by St. John Koukouzeles’ piece

    Directory of Open Access Journals (Sweden)

    Maria Alexandru

    2012-01-01

    Full Text Available The present paper explores some aspects of the so-called kalophonic musical style which flourished during the last centuries of Byzantium. It focuses on a masterpiece by St. John Koukouzeles, namely the epibole Φρούρησον πανένδοξε (Ο Allglorious, keep watch over the city, in honor of St. Demetrios, the protector of Thessaloniki, and is complementary to some previous musicological analysis of this piece by Stephania Meralidou. After a brief presentation of the old sticheron Ἔχει μὲν ἡ θειοτάτη σου ψυχή, whereof St. John takes his departing point for the kalophonic composition, the paper concentrates on a multi-level analysis of the epibole, firstly on the ground of the late middle-Byzantine notation, according to the ms Vlatadon 46 (A.D. 1551, and secondly by comparing the old notation to its slow exegesis in new-Byzantine notation by Chourmouzios Chartophylax (score and recording issued by the Greek Byzantine Choir, dir. L. Angelopoulos.The analysis comprises several approaches like textual, music-architectural, modal, micro-syntactical, rhetorical, macro-syntactical, generative, comparative (cf. plates 7-12, 17-20. Since this material is also suitable for didactic purposes, the different plates are given again in the appendix, in form of exercises to be filled in by interested students.The different analytical approaches reveal the highly refined melodic fabric of kalophonia with its plethora of theseis-combinations, the extensive use of music-rhetorical devices, basic norms of the complex art of musical exegesis in this style, as well as the beauty of this kind of melodies, which have been acknowledged to represent the ‘zenith’ of Byzantine music (Wellesz.

  5. A One-Piece Lunar Regolith-Bag Garage Prototype

    Science.gov (United States)

    Smithers, Gweneth A.; Nehls, Mary K.; Hovater, Mary A.; Evans, Steven W.; Miller, J. Scott; Broughton, Roy M.; Beale, David; Killing-Balci, Fatma

    2007-01-01

    Shelter structures on the moon, even in early phases of exploration, should incorporate lunar materials as much as possible. We designed and constructed a prototype for a one-piece regolith-bag unpressurized garage concept, and, in parallel, we conducted a materials testing program to investigate six candidate fabrics to learn how they might perform in the lunar environment. In our concept, a lightweight fabric form is launched from Earth to be landed on the lunar surface and robotically filled with raw lunar regolith. In the materials testing program, regolith-bag fabric candidates included: Vectran(TM), Nextel(TM), Gore PTFE Fabric(TM), Zylon(TM), Twaron(TM), and Nomex(TM). Tensile (including post radiation exposure), fold, abrasion, and hypervelocity impact testing were performed under ambient conditions, and, within our current means, we also performed these tests under cold and elevated temperatures. In some cases, lunar simulant (JSC-1) was used in conjunction with testing. Our ambition is to continuously refine our testing to reach lunar environmental conditions to the extent possible. A series of preliminary structures were constructed during design of the final prototype. Design is based on the principles of the classic masonry arch. The prototype was constructed of Kevlar(TM) and filled with vermiculite (fairly close to the weight of lunar regolith on the moon). The structure is free-standing, but has not yet been load tested. Our plan for the future would be to construct higher fidelity mockups with each iteration, and to conduct appropriate tests of the structure.

  6. Research on Double CCD Dimensional Metrology Applying in Large Forge Piece

    International Nuclear Information System (INIS)

    Hu, C H; Xiong, Z

    2006-01-01

    As development of computer vision, stereoscopic vision sensors have been used more and more widely, and double CCD vision sensor with its simplicity of operator, highaccuracy and high-efficiency has been used in many spheres. It can be used in dimensional metrology of large forge piece, which greatly improves the efficiency and accuracy of large forge piece measurement

  7. Enumeration of pyramids of one-dimensional pieces of arbitrary fixed integer length

    DEFF Research Database (Denmark)

    Durhuus, Bergfinnur; Eilers, Søren

    We consider pyramids made of one-dimensional pieces of fixed integer length a and which may have pairwise overlaps of integer length from 1 to a. We prove that the number of pyramids of size m, i.e. consisting of m pieces, equals (am-1,m-1) for each a >= 2. This generalises a well known result...

  8. Bacteriological evaluation for one-and two-piece implant design supporting mandibular overdenture.

    Science.gov (United States)

    Abdelwahed, Ahmed; Mahrous, Ahmed I; Abadallah, Mohamed Farouk; Asfour, Hani; Aldawash, Hussien A; Alagha, Ebaa I

    2015-01-01

    This study evaluated and compared the bacteriological effect of two-piece implants and one-piece implants in complete overdenture cases on supporting structures. Ten male completely edentulous patients were selected and randomly divided into two equal groups according to the implant design and surgical technique for this study; Group 1: Patients were rehabilitated with complete mandibular overdenture supported by two-piece implants one on each side of the lower arch following two-stage surgical technique and Group 2: Patients were rehabilitated with complete mandibular overdenture supported by one-piece implants one on each side. Evaluation was made at the time of insertion, 6, 12, and 18 months after overdenture insertion, by measuring bacteriological changes around implants abutments. Complete overdenture supported by one-piece implants showed better effect on the bacteriological changes as compared to that supported by two-piece implants. Complete overdenture supported by one-piece implants one on each side of the lower arch showed better effect on the bacteriological changes than using the same prosthesis supported by two-piece implants.

  9. Successful mandible rehabilitation of lower incisors with one-piece implants.

    Science.gov (United States)

    Lauritano, Dorina; Grassi, Roberto; di Stasio, Dario; Lucchese, Alberta; Petruzzi, Massimo

    2014-12-05

    The popularity of one-piece implants has increased considerably among patients and dentists. The advantages of one-piece immediate loading are to reduce the number of interventions. These parameters can be better controlled with a one-piece implant. We considered 21 patients with one-piece implants inserted in mandible for this retrospective study. Inclusion criteria were: good oral hygiene, absence of lesions of the oral mucosa, no smoking or smoking less than 20 cigarettes a day, drinking less than two glasses of wine a day, good general health and no pregnancy. We enrolled 21 (12 women and 9 men) patients in this retrospective study. The mean follow-up was 1 year. A total of 84 one-piece implants were inserted in mandible to replace 42 lower first and 42 second incisors. The diameter of the implants was 3.0mm in all fixtures. The length of the implants was equal to or longer than 12 mm in 44 and 40 fixtures respectively. Of these, 48 were inserted in women and 36 in men (age range 33 to 67; mean age 58.3 years). There is no difference between the survival rates of one-piece immediate loading implants and two-piece implants and delayed loading. In conclusion, a one-piece immediate loading implant is a reliable device for mandible rehabilitation.

  10. Short- and Long-Term Musical Preferences: What Makes a Favourite Piece of Music?

    Science.gov (United States)

    Lamont, Alexandra; Webb, Rebecca

    2010-01-01

    Within the growing field of music preferences, little is currently known about the concept of a favourite piece of music. The current study explores listeners' nominated favourite pieces of music over short and longer time-spans, combining diary and interview methods to uncover what a favourite means, how stable it is, and what factors influence…

  11. Material Composition of Bucket Foundation Transition Piece for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Nezhentseva, Anastasia; Andersen, Lars; Ibsen, Lars Bo

    2010-01-01

    . This paper deals with the transition piece for a relatively novel type of foundation, the so-called suction bucket (caisson), focusing on the design of a transition piece connecting the turbine column with a suction bucket used as a monopod foundation for an offshore wind turbine. Since the current design...

  12. Piece2.0: an update for the pant gene structure comparison and evolution database

    Science.gov (United States)

    PIECE (Plant Intron Exon Comparison and Evolution) is a web-accessible database that houses intron and exon information of plant genes. PIECE serves as a resource for biologists interested in comparing intron–exon organization and provides valuable insights into the evolution of gene structure in pl...

  13. Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

    Science.gov (United States)

    Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

    2018-04-01

    A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

  14. In vitro fatigue and fracture resistance of one- and two-piece CAD/CAM zirconia implant abutments.

    Science.gov (United States)

    Gehrke, Peter; Johannson, Dirk; Fischer, Carsten; Stawarczyk, Bogna; Beuer, Florian

    2015-01-01

    All-ceramic abutments are employed increasingly often in implant dentistry for esthetic reasons. In vitro stress testing is required to evaluate the suitability of these constructions, especially in load-bearing posterior regions. The purpose of the study was to assess and compare the fatigue and fracture resistance of one- and two-piece computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia implant abutments with an internal-hex connection and prefabricated commercially available zirconia stock abutments. Twenty-one abutment-crown specimens were prepared for three test groups. Control group 1 (SZ) included specimens with unprepared stock zirconia abutments, test group 2 (OP) included one-piece CAD/CAM zirconia abutments, and test group 3 (TP) included two-piece CAD/CAM zirconia abutments. All 21 specimens underwent thermocycling and fatigue testing. Finally, all specimens were tested for fracture resistance with a universal testing machine. The maximum load was applied to the tapered occlusal area of each crown at a 30-degree angle and a crosshead speed of 0.5 mm/min until the implant-abutment connection failed. Kolmogorov-Smirnov, Shapiro-Wilk, and post-hoc Scheffé tests were used for statistical analysis. All abutments in groups SZ and OP fractured into two or more pieces after fracture resistance testing. None of the TP abutments displayed apparent disintegration, but failure was evidenced by bending of the retention screw. OP abutments (232.1 ± 29.8 N) and SZ abutments (251.8 ± 23.2 N) showed lower fracture loads than the TP abutments (291.4 ± 27.8 N). However, only the difference between the OP and TP groups was statistically significant. Further load-displacement analyses corroborated the higher mechanical stability of the TP abutments. Superior resistance was achieved for two-piece hybrid CAD/CAM zirconia abutments. These abutments might be clinically beneficial in high-load areas, such as premolar and molar regions.

  15. Two-piece ALIF cage optimizes the bone-implant interface in a 360° setting.

    Science.gov (United States)

    Wilke, Hans-Joachim; Volkheimer, David; Robie, Bruce; Christensen, Finn B

    2017-11-01

    Clinical research has documented that cage subsidence and the loss of balance correction is a significant complication related to spinal fusion. Subsidence is a multifactorial complication, where implant design is one important element. The aim of the study is to compare the rigidity and bone-implant relative motion of segments treated with either a conventional one-piece ALIF cage versus a two-piece ALIF cage, which adapts in situ and permits 7°-21° of lordosis. Seven lumbosacral (L3-S1) human cadaver specimens were tested in a universal spine tester in the intact condition, the specimens instrumented with a two-piece ALIF cage (Statur ® -L, FBC Device, Denmark) and a one-piece ALIF cage (Pezo™-A, Ulrich GmbH & Co. KG., Germany), both supplemented with a pedicle screw system using pure moments of ±7.5 Nm in three principal motion directions. For assessment of the bone-implant interface, fluoroscopic videos were captured during motion and 3D motion was measured using an optical motion capturing system. Significantly less motion at the implant-endplate interface was found for the two-piece cage (1.0° ± 0.6°) in comparison to the one-piece cage (4.2° ± 1.7°) in flexion/extension. No significant differences in segment rigidity were found between the one-piece and two-piece cages in the 360° setup, while both configurations significantly reduced the range of motion compared to the intact condition (p one-piece ALIF cages, the two-piece cage concept reduced the relative motion at the bone-implant interface without compromising stability.

  16. From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials.

    Science.gov (United States)

    D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R; Sacks, Michael S

    2014-11-01

    In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Preparation and characterization of functionalized single walled carbon nanotubes (fSWCNT)/ Hydroxyapatite (HAp)-Nylon hybridized composite biomaterial to study the mechanical properties

    Science.gov (United States)

    Khanal, Suraj; Leventouri, Theodora; Mahfuz, Hassan; Rondinone, Adam

    2014-03-01

    Synthetic hydroxyapatite (HAp) bears poor mechanical properties that limit its applicability in orthopedics. We study the possibility of overcoming such limitations by incorporating functionalized single walled carbon nanotubes (fSWCNT) in a biocompatible/bioactive nano-composite. We present results from synthesis and characterization of samples prepared under different processing parameters. Ultra sonication method was to disperse functionalized single walled carbon nanotubes (fSWCNT) in HAp followed by a simple hot assorting method to incorporate with polymerized ɛ-caprolactam. The fracture toughness of the composite materials was tested in compliance with the ASTM D-5045 standard. We have found that while the fracture toughness strongly depends on the processing parameters, a value comparable to the one for cortical bone is achieved. Mechanical properties, electron microscopy and crystal structure properties of the composite materials will be discussed.

  18. Two-color spectroscopy of UV excited ssDNA complex with a single-wall nanotube probe: Fast nucleobase autoionization mechanism

    OpenAIRE

    Ignatova, Tetyana; Balaeff, Alexander; Zheng, Ming; Blades, Michael; Stoeckl, Peter; Rotkin, Slava V.

    2015-01-01

    DNA autoionization is a fundamental process wherein UV-photoexcited nucleobases dissipate energy by charge transfer to the environment without undergoing chemical damage. Here, single-wall carbon nanotubes (SWNT) are explored as a photoluminescent reporter for studying the mechanism and rates of DNA autoionization. Two-color photoluminescence spectroscopy allows separate photoexcitation of the DNA and the SWNTs in the UV and visible range, respectively. A strong SWNT photoluminescence quenchi...

  19. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  20. Homogeneous and single-side-operational connector mechanism for self-reconfigurable, self-assembly and self-healing systems

    Science.gov (United States)

    Shen, Wei-Min (Inventor); Kovac, Robert M. (Inventor)

    2012-01-01

    Designs of single-end-operative reconfigurable genderless connectors that include a base, a plurality of movable jaws that are formed on the base and can engage to the jaws of another connector, and an actuator that is mounted on the base and can engage and move the jaws of the reconfigurable connector to connect the reconfigurable connector with another connector.

  1. Landing mechanics during single hop for distance in females following anterior cruciate ligament reconstruction compared to healthy controls.

    Science.gov (United States)

    Trigsted, Stephanie M; Post, Eric G; Bell, David R

    2017-05-01

    To determine possible differences in single-hop kinematics and kinetics in females with anterior cruciate ligament reconstruction compared to healthy controls. A second purpose was to make comparisons between the healthy and reconstructed limbs. Subjects were grouped based on surgical status (33 ACLR patients and 31 healthy controls). 3D motion capture synchronized with force plates was used to capture the landing phase of three successful trials of single hop for distance during a single data collection session. Peak values during the loading phase were analysed. Subjects additionally completed three successful trials of the triple hop for distance Tegner activity scale and International Knee Document Committee 2000 (IKDC). Controls demonstrated greater peak knee flexion and greater internal knee extension moment and hip extension moment than ACLR subjects. Within the ACLR group, the healthy limb exhibited greater peak knee flexion, hip flexion, hip extension moment, single hop and triple hops for distance and normalized quadriceps strength. Patients who undergo anterior cruciate ligament reconstruction land in a more extended posture when compared to healthy controls and compared to their healthy limb. III.

  2. A Polypeptide-DNA Hybrid with Selective Linking Capability Applied to Single Molecule Nano-Mechanical Measurements Using Optical Tweezers

    NARCIS (Netherlands)

    Moayed, F.; Mashaghi, A.; Tans, S.J.

    2013-01-01

    Many applications in biosensing, biomaterial engineering and single molecule biophysics require multiple non-covalent linkages between DNA, protein molecules, and surfaces that are specific yet strong. Here, we present a novel method to join proteins and dsDNA molecule at their ends, in an

  3. Memory structures for encoding and retrieving a piece of music: an ERP investigation.

    Science.gov (United States)

    Williamon, Aaron; Egner, Tobias

    2004-12-01

    This study examined behavioral and neural correlates of expert musical memory, specifically the hypothesis that particular bars within a complex piece of music would serve as structural markers for encoding to and retrieval from memory. Six pianists were asked to learn and memorize a set prelude by J.S. Bach for performance, and to identify bars that they employed for structuring the prelude into component sections. Following performance from memory, the participants took part in a visual recognition memory task, in which single bars from the prelude had to be distinguished from matched new bars. During the recognition task, the electroencephalogram (EEG) was recorded, and event-related potentials (ERPs) from correctly identified prelude stimulus trials were averaged according to their hypothesized status into "structural" and "nonstructural" bars. The results showed that correct identification of structural bars was significantly faster (and tended to display higher accuracy) than recognition of non-structural ones. In addition, recognition of structural bars was associated with a significantly greater negative ERP peak of 300-400 ms latency and a right centro-parietal scalp distribution. This mid-latency negativity appears to index processing of stimuli that served as cues for encoding and retrieval of a complex semantic structure, and is qualitatively and conceptually different from other previously identified recognition memory ERPs (such as the "old/new" effect), as well as from the classic N400 ERP. The data support existing theories of expert memory and music cognition.

  4. Early clinical experience with a new preloaded one-piece intraocular lens in paediatric cataract surgery.

    Science.gov (United States)

    Gosling, D B; Chan, T K J

    2016-09-01

    PurposeTo report the clinical experience of using the Tecnis PCB00 (Abbott Medical Optics, Santa Ana, CA, USA) preloaded one-piece intraocular lens (IOL) in the setting of a tertiary referral centre for paediatric cataract.MethodsA retrospective case note review of all paediatric cataract surgeries using the Tecnis PCB00 IOL, at a single UK paediatric ophthalmology department.ResultsNine eyes in seven patients received the IOL between December 2014 and January 2016. All patients underwent lens aspiration and insertion of the IOL 'in the bag.' The indications for surgery included developmental cataract (8/9) and traumatic cataract (1/9). Mean age at the time of surgery was 7 years (range 2-14). The median improvement in logMAR best-corrected visual acuity was 0.475 (range 0.250-1.500). The mean follow-up duration was 5 months (range 1-13). No operative or post-operative complications occurred as a result of using the device.ConclusionThe Tecnis PCB00 preloaded IOL appears to be a safe and effective device in treating paediatric cataract.

  5. Biological Width around One- and Two-Piece Implants Retrieved from Human Jaws

    Directory of Open Access Journals (Sweden)

    Ricardo Judgar

    2014-01-01

    Full Text Available Several histologic studies regarding peri-implant soft tissues and biological width around dental implants have been done in animals. However, these findings in human peri-implant soft tissues are very scarce. Therefore, the aim of this case series was to compare the biological width around unloaded one- and two-piece implants retrieved from human jaws. Eight partially edentulous patients received 2 test implants in the posterior mandible: one-piece (solid implants that comprise implant and abutment in one piece and two-piece (external hexagon with a healing abutment implants. After 4 months of healing, the implants and surrounding tissue were removed for histologic analysis. The retrieved implants showed healthy peri-implant bone and exhibited early stages of maturation. Marginal bone loss, gaps, and fibrous tissue were not present around retrieved specimens. The biologic width dimension ranged between 2.55 ± 0.16 and 3.26 ± 0.15 to one- and two-piece implants, respectively (P0.05. Within the limits of this study, it could be shown that two-piece implants resulted in the thickening of the connective tissue attachment, resulting in the increase of the biological width, when compared to one-piece implants.

  6. Biological width around one- and two-piece implants retrieved from human jaws.

    Science.gov (United States)

    Judgar, Ricardo; Giro, Gabriela; Zenobio, Elton; Coelho, Paulo G; Feres, Magda; Rodrigues, Jose A; Mangano, Carlo; Iezzi, Giovanna; Piattelli, Adriano; Shibli, Jamil Awad

    2014-01-01

    Several histologic studies regarding peri-implant soft tissues and biological width around dental implants have been done in animals. However, these findings in human peri-implant soft tissues are very scarce. Therefore, the aim of this case series was to compare the biological width around unloaded one- and two-piece implants retrieved from human jaws. Eight partially edentulous patients received 2 test implants in the posterior mandible: one-piece (solid implants that comprise implant and abutment in one piece) and two-piece (external hexagon with a healing abutment) implants. After 4 months of healing, the implants and surrounding tissue were removed for histologic analysis. The retrieved implants showed healthy peri-implant bone and exhibited early stages of maturation. Marginal bone loss, gaps, and fibrous tissue were not present around retrieved specimens. The biologic width dimension ranged between 2.55 ± 0.16 and 3.26 ± 0.15 to one- and two-piece implants, respectively (P 0.05). Within the limits of this study, it could be shown that two-piece implants resulted in the thickening of the connective tissue attachment, resulting in the increase of the biological width, when compared to one-piece implants.

  7. Gene expression suggests double-segmental and single-segmental patterning mechanisms during posterior segment addition in the beetle Tribolium castaneum.

    Science.gov (United States)

    Janssen, Ralf

    2014-01-01

    In the model arthropod Drosophila, all segments are patterned simultaneously in the blastoderm. In most other arthropods, however, posterior segments are added sequentially from a posterior segment addition zone. Posterior addition of single segments likely represents the ancestral mode of arthropod segmentation, although in Drosophila, segments are patterned in pairs by the pair-rule genes. It has been shown that in the new model insect, the beetle Tribolium, a segmentation clock operates that apparently patterns all segments in pairs as well. Here, I report on the expression of the segment polarity gene H15/midline in Tribolium. In the anterior embryo, segmental stripes of H15 appear in pairs, but in the posterior of the embryo stripes appear in a single-segmental periodicity. This implies that either two completely different segmentation-mechanisms may act in the germ band of Tribolium, that the segmentation clock changes its periodicity during development, or that the speed in which posterior segments are patterned changes. In any case, the data suggest the presence of another (or modified), yet undiscovered, mechanism of posterior segment addition in one of the best-understood arthropod models. The finding of a hitherto unrecognized segmentation mechanism in Tribolium may have major implications for the understanding of the origin of segmentation mechanisms, including the origin of pair rule patterning. It also calls for (re)-investigation of posterior segment addition in Tribolium and other previously studied arthropod models.

  8. Studies of the kinetics and mechanisms of ammonia synthesis and hydrodesulfurization on metal single-crystal surfaces

    International Nuclear Information System (INIS)

    Gellman, A.J.; Asscher, M.; Somorjai, G.A.

    1985-01-01

    The authors studied the ammonia synthesis reaction over Fe and Re single crystal surfaces and the hydrodesulfurization of thiophene over the Mo(100) single crystal surface. The studies have been performed using UHV surface science tools with the capability of exposing the surfaces to high pressure, high temperature reaction conditions. The ammonia synthesis reaction was shown to be extremely sensitive to surface structure on both Fe and Re, favoring surfaces with a rough or open topography. The HDS reaction on the Mo(100) surface has been shown to be similar to that on MoS/sub 2/ and appears to proceed via a reaction path that does not produce a strong Mo-S bond as an intermediate species

  9. Final report on the UKAEA defect detection trials on test pieces 3 and 4. December 1982

    International Nuclear Information System (INIS)

    Lock, D.L.; Cowburn, K.J.

    1983-03-01

    The report follows ND-R-845(R) which described the scope, inspection procedures and results of the defect detection trials on test pieces 3 and 4. The work has been aimed at assessing the ability of non-destructive testing techniques, to detect and size defects near the clad/base metal interface of a flat piece and the inner radius of a PWR inlet nozzle. Following the destructive examination of the test pieces at Ispra, the true sizes of the intended defects are now known. These sizes are compared with that intended and the performance of the inspection teams reviewed. (author)

  10. Classification of delocalization power of global unitary operations in terms of LOCC one-piece relocalization

    Directory of Open Access Journals (Sweden)

    Akihito Soeda

    2010-06-01

    Full Text Available We study how two pieces of localized quantum information can be delocalized across a composite Hilbert space when a global unitary operation is applied. We classify the delocalization power of global unitary operations on quantum information by investigating the possibility of relocalizing one piece of the quantum information without using any global quantum resource. We show that one-piece relocalization is possible if and only if the global unitary operation is local unitary equivalent of a controlled-unitary operation. The delocalization power turns out to reveal different aspect of the non-local properties of global unitary operations characterized by their entangling power.

  11. Collide@CERN: exclusive open rehearsal of Gilles Jobin's last piece

    CERN Multimedia

    2012-01-01

    Collide@CERN and Gilles Jobin, artist in residency at CERN, present an exclusive open rehearsal of his last piece SPIDER GALAXIES Tuesday 31 July 2012 - A new piece created to open new territories of the mind - Join us in Restaurant 1 from 4 p.m. (next to the Glass Box Restaurant) With this piece, the body turns into matter, which is complete, spatial and sensual. Come and see Gilles Jobin and his dancers. With a score by Cristian Vogel and Carla Scaletti invoking sound particles, while Daniel Demont disperses the spectrum. Protean, infinitely large or infinitesimal, such are the Spider Galaxies.    

  12. The influnece of the partial single reduction on mechanical properties wires made from trip steel with 0,43 % C

    Directory of Open Access Journals (Sweden)

    S. Wiewiórowska

    2015-01-01

    Full Text Available Large strain inhomogeneity is caused by the shape of deformation zone of die and by the friction between tool and deformed wire for multistage wire drawing processes. The influence on the value of the redundant strain by the use of different partial single reductions during all wire drawing process was observed. This problem is particularly important for TRIP steel wires drawing processes because the strain intensity influences on the speed of retained austenite transformation into martensite.

  13. Surface growth mechanisms and structural faulting in the growth of large single and spherulitic titanosilicate ETS-4 crystals

    Science.gov (United States)

    Miraglia, Peter Q.; Yilmaz, Bilge; Warzywoda, Juliusz; Sacco, Albert

    2004-10-01

    Morphological, surface and crystallographic analyses of titanosilicate ETS-4 products, with diverse habits ranging from spherulitic particles composed of submicron crystallites to large single crystals, are presented. Pole figures revealed that crystal surfaces with a-, b- and c- axes corresponded to , and directions, respectively. Thus, technologically important 8-membered ring pores and titania chains in ETS-4 run along the b-axis of single crystals and terminate at the smallest crystal face. Height of the spiral growth steps observed on {1 0 0} and {0 0 1} surfaces corresponded to the interplanar spacings associated with their crystallographic orientation, and is equivalent to the thickness of building units that form the ETS-4 framework. Data suggest that the more viscous synthesis mixtures, with a large driving force for growth, increased the two- and three-dimensional nucleation, while limiting the transport of nutrients to the growth surface. These conditions increase the tendency for stacking fault formation on {1 0 0} surfaces and small angle branching, which eventually results in spherulitic growth. The growth of high quality ETS-4 single crystals (from less viscous synthesis mixtures) occurred at lower surface nucleation rates. Data suggest that these high quality, large crystals grew due to one-dimensional nucleation at spiral hillocks, and indicate that under these conditions un-faulted growth is preferred.

  14. Fluid balance and length of mechanical ventilation in children admitted to a single Pediatric Intensive Care Unit.

    Science.gov (United States)

    Vidal, Solange; Pérez, Augusto; Eulmesekian, Pablo

    2016-08-01

    Associations between cumulative fluid balance and a prolonged duration of assisted mechanical ventilation have been described in adults. The aim of this study was to evaluate whether fluid balance in the first 48 hours of assisted mechanical ventilation initiation was associated with a prolonged duration of this process among children in the Pediatric Intensive Care Unit (PICU). Retrospective cohort of patients in the PICU o, Hospital Italiano de Buenos Aires, between 1/1/2010 and 6/30/2012. Balance was calculated in percentage of body weight; prolonged mechanical ventilation was defined as >7 days, and confounders were registered. Univariate and multivariate analyses were performed. Two hundred and forty-nine patients were mechanically ventilated for over 48 hours; 163 were included in the study. Balance during the first 48 hours of mechanical ventilation was 5.7% ± 5.86; 82 patients (50.3%) were on mechanical ventilation for more than 7 days. Age 〈 4 years old (OR 3.21, 95% CI 1.38-7.48, p 0.007), respiratory disease (OR 4.94, 95% CI 1.51-16.10, p 0.008), septic shock (OR 4.66, 95% CI 1.10-19.65, p 0.036), Pediatric Logistic Organ Dysfunction (PELOD) 〉 10 (OR 2.44, 95% CI 1.234.85, p 0.011), and positive balance 〉 13% (OR 4.02, 95% CI 1.08-15.02, p 0.038) were associated with prolonged mechanical ventilation. The multivariate model resulted in an OR 2.58, 95% CI: 1.17-5.58, p= 0.018 for PELOD 〉 10, and an OR 3.7, 95% CI: 0.91-14.94, p= 0.066 for positive balance 〉 13%. Regarding prolonged mechanical ventilation, the multivariate model showed an independent association with organ dysfunction (PELOD 〉 10) and a trend towards an association with positive balance 〉 13%. Sociedad Argentina de Pediatría.

  15. Comparative Efficacy and Mechanisms of a Single-Session Pain Psychology Class in Chronic Low Back Pain: Study Protocol for a Randomized Controlled Trial.

    Science.gov (United States)

    Darnall, Beth D; Ziadni, Maisa S; Roy, Anuradha; Kao, Ming-Chih; Sturgeon, John A; Cook, Karon F; Lorig, Kate; Burns, John W; Mackey, Sean C

    2018-03-06

    The Institute of Medicine (IOM) reported that chronic pain affects about 100 million U.S. adults, with chronic low back pain (CLBP) cited as the most prevalent type. Pain catastrophizing is a psychological construct shown to predict the development and trajectory of chronic pain and patient response to pain treatments. While effective treatment for pain catastrophizing typically includes eight-session groups of cognitive behavioral therapy (CBT), a single-session targeted treatment class yielded promising results which, if replicated and extended, could prove to efficiently and cost-effectively reduce pain catastrophizing. In this trial, we seek to determine the comparative efficacy of this novel single-session pain catastrophizing class to an eight-session course of pain CBT and a single-session back pain health education class. We will also explore the psychosocial mechanisms and outcomes of pain catastrophizing treatment. In this trial we will randomize 231 individuals with CLBP to one of three treatment arms: (1) pain-CBT (eight weekly 2-h group sessions with home exercises and readings); (2) a single 2-h pain catastrophizing class; or (3) a single 2-h back pain health education class (active control). For the primary outcome of pain catastrophizing, the trial is designed as a non-inferiority test between pain-CBT and the single-session pain catastrophizing class, and as a superiority test between the single-session pain catastrophizing class and the health education class. Team researchers masked to treatment assignment will assess outcomes up to six months post treatment. If the single-session targeted pain catastrophizing class is found to be an effective treatment for patients with CLBP, this low cost and low burden treatment could dismantle many of the current barriers and burdens of effective pain care. Further, elucidation of the mechanisms of pain catastrophizing treatments will facilitate future research on the topic as well as further development and

  16. The kinematics and mechanics of leaf expansion: new pieces to the Arabidopsis puzzle.

    Science.gov (United States)

    Szymanski, Daniel B

    2014-12-01

    Leaves are the primary organs for photosynthesis, and their angle, size, and timing of deployment determine the light capture efficiency of the canopy. Therefore, leaf development is an important trait in both natural and managed populations. In dicot leaves, the spatial and temporal patterns of cell division and expansion are heterogeneous, and a long-standing challenge has been to understand how subcellular and cellular growth processes can operate across broad spatial scales to influence the macroscopic growth of leaves. This review focuses on recent time-lapse analyses that help to clarify relationships between the polarized growth of individual cells, the growth behaviors of cell clusters, and leaf morphology.

  17. Single-Molecule Titration in a Protein Nanoreactor Reveals the Protonation/Deprotonation Mechanism of a C:C Mismatch in DNA.

    Science.gov (United States)

    Ren, Hang; Cheyne, Cameron G; Fleming, Aaron M; Burrows, Cynthia J; White, Henry S

    2018-04-18

    Measurement of single-molecule reactions can elucidate microscopic mechanisms that are often hidden from ensemble analysis. Herein, we report the acid-base titration of a single DNA duplex confined within the wild-type α-hemolysin (α-HL) nanopore for up to 3 h, while monitoring the ionic current through the nanopore. Modulation between two states in the current-time trace for duplexes containing the C:C mismatch in proximity to the latch constriction of α-HL is attributed to the base flipping of the C:C mismatch. As the pH is lowered, the rate for the C:C mismatch to flip from the intra-helical state to the extra-helical state ( k intra-extra ) decreases, while the rate for base flipping from the extra-helical state to the intra-helical state ( k extra-intra ) remains unchanged. Both k intra-extra and k extra-intra are on the order of 1 × 10 -2 s -1 to 1 × 10 -1 s -1 and remain stable over the time scale of the measurement (several hours). Analysis of the pH-dependent kinetics of base flipping using a hidden Markov kinetic model demonstrates that protonation/deprotonation occurs while the base pair is in the intra-helical state. We also demonstrate that the rate of protonation is limited by transport of H + into the α-HL nanopore. Single-molecule kinetic isotope experiments exhibit a large kinetic isotope effect (KIE) for k intra-extra ( k H / k D ≈ 5) but a limited KIE for k extra-intra ( k H / k D ≈ 1.3), supporting our model. Our experiments correspond to the longest single-molecule measurements performed using a nanopore, and demonstrate its application in interrogating mechanisms of single-molecule reactions in confined geometries.

  18. H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts: Hydrothermal preparation and formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Chang, K.-H. [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Hu, C.-C. [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621, Taiwan (China)], E-mail: cchu@che.nthu.edu.tw

    2007-10-15

    The formation mechanism of highly pure H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts is clarified in a hydrothermal synthesis process with a specially designed precursor solution containing V{sup 5+} and V{sup 4+} in a fixed ratio of 2/1. This specially designed precursor solution provides an additional merit for the rapid fabrication of highly pure H{sub 2}V{sub 3}O{sub 8} nanobelts through a simple hydrothermal route. During the hydrothermal synthesis process, V{sup 5+} species initially reacts with some V{sup 4+} to form a metastable, whisker-like V{sub 10}O{sub 24} . nH{sub 2}O (n < 12). The V{sup 5+} species dissolved from the whisker-like V{sub 10}O{sub 24} . nH{sub 2}O reacts continuously with residual V{sup 4+} ions in the precursor solution to form seeds of H{sub 2}V{sub 3}O{sub 8} single-crystals. The anisotropic growth of H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts with length > 10 {mu}m and width between 50 and 150 nm occurs with prolonging the hydrothermal time. Finally, highly pure H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts are obtained when the hydrothermal time reaches 4 h. The textures of vanadium oxides prepared at different hydrothermal times are systematically compared through X-ray diffraction, transmission electron microscopic and X-ray photoelectron spectroscopic analyses to clarify the synthesis mechanism of H{sub 2}V{sub 3}O{sub 8} single-crystal nanobelts.

  19. OVERVIEW OF WORK PIECE TEMPERATURE MEASUREMENT TECHNIQUES FOR MACHINING OF Ti6Al4V#

    Directory of Open Access Journals (Sweden)

    P.J.T. Conradie

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Ti6Al4V is one of the most widely used titanium alloys in aerospace applications, but its machining remains a challenge. Comprehensive research has been done in the past, mainly investigating tool failure of various materials. Less research has been done to investigate the thermal effect of machining on work piece quality, including fatigue performance. Temperature measurement is considered to be a key enabling technology. This study presents an overview of current temperature measurement techniques for machined and tool surfaces. Two categories of methods were investigated: slower contact, and faster optical methods. Optical fibre two colour pyrometry experiments are reported that demonstrate the technique’s adequate response time. The infrared camera temperature measurement experiments synchronised temperature measurement with visual observation, aimed at mechanism analysis. The results corresponded with the literature.

    AFRIKAANSE OPSOMMING: Ti6Al4V is een van die mees gewilde lugvaart allooie, maar sy masjinering is ’n uitdaging. Bestaande navorsing dek beitelslytasie omvattend. Die termiese effek van masjinering op werkstuk integriteit, insluitend vermoeiingleeftyd, het egter veel minder dekking geniet. Temperatuurmeting wat in hierdie studie ondersoek word, word as ’n sleuteltegnologie beskou. Twee kategorië metodes is ondersoek, nl stadige kontakmetodes en optiese metodes met vinnige respons, wat die meting van oorgangsverskynsels moontlik maak. Eksperimentele werk wat beide optiese vesel tweekleurpirometrie en termiese kamera tegnieke insluit bewys die tegnieke as geskik vir die benodigde navorsing.

  20. Study of the curvature of green pieces in stoneware ceramic tiles

    Directory of Open Access Journals (Sweden)

    de Pablos, A.

    2000-02-01

    Full Text Available Ceramic tiles undergo some deformations on the production line. After pressing, tiles are flat but, in subsequent stages of the production line, surfaces are wetted producing temperature and water gradients across their thickness. These gradients generate curvature in the tiles and therefore deformations in the pieces. The aim of the present work has been to measure the curvature and the mechanical properties of the tiles as a function of the water absorption for two types of ceramic pastes.

    Las baldosas cerámicas sufren deformaciones durante su proceso en línea de producción. Cuando las baldosas salen de la prensa presentan una superficie plana, pero en las siguientes etapas de la línea de producción la superficie de las muestras se humedece, produciéndose gradientes de temperatura y humedad que dan lugar a una deformación por curvatura de la pieza. El objetivo de este trabajo es estudiar dicha curvatura y las propiedades mecánicas de las baldosas en función de la humedad absorbida en dos tipos de pastas cerámicas.

  1. Postnatal risk environments, epigenetics, and psychosis: putting the pieces together.

    Science.gov (United States)

    Kundakovic, Marija

    2014-10-01

    Postnatal environmental factors, such as early life adversity, cannabis use, and social stressors are associated with increased risk for psychotic disorders. Understanding mechanisms that underlie increased psychosis risk is of great importance for the development of novel preventive approaches and early interventions. In a timely review article, Pishva et al. discuss available evidence suggesting that postnatal environmental risk factors contribute to psychotic disorders via epigenetic mechanisms. While the evidence supporting this hypothesis is limited and primarily based on the epigenetic profiling of psychotic patients and animal models, further investigation in this area is warranted and may bring exciting results.

  2. Simulation of Double-Seaming in a Two-piece Aluminum Can

    Science.gov (United States)

    Romanko, Anne; Berry, Dale; Fox, David

    2004-06-01

    The aluminum can industry in the United States and Canada manufactures over 100 billion cans per year. Two-piece aluminum cans are commonly used to seal and deliver foodstuffs such as soft drinks, beer, pet food, and other perishable items. In order to ensure product safety and performance, the double seam between the can body and lid is a critical component of the package. Double-seaming is a method by which the flange of the can body and the curl of the end are folded over together such that the final joint is composed of five metal thicknesses. There are a number of design challenges involved with the art of double seaming, especially with the push to lightweight. Although the requirements vary by product, the typical beer package must be able to hold pressures in excess of 90psi. In addition, in production, double seaming is a high-speed operation with speeds as high as 3000 cans/minute on an 18-spindle seamer. For this high volume, low cost industry, understanding and optimizing the seaming process can advance the industry as well as help prevent various manufacturing problems that produce a poor seal between the two pieces of the can. To aid in understanding the mechanics of the can parts during double-seaming, a simulation procedure was developed and carried out on a 202 diameter beverage can and lid. Simulations were run with the explicit dynamics solver ABAQUS/Explicit using the continuum shell element technology available in the ABAQUS general purpose FEA program. The continuum shell is a shear-deformable shell element with the topology of an eight node brick. The element's formulation allows continuously varying, solution-dependent shell thickness and through-thickness pinching stress. One important advantage of using the continuum shell as opposed to a traditional shell element is that true contact interactions at the top and bottom surfaces of the can body and lid can be accurately modeled. With a conventional shell element, contact is performed at the

  3. Simulation of double-seaming in a two-piece aluminum can

    International Nuclear Information System (INIS)

    Romanko, Anne; Berry, Dale; Fox, David

    2004-01-01

    The aluminum can industry in the United States and Canada manufactures over 100 billion cans per year. Two-piece aluminum cans are commonly used to seal and deliver foodstuffs such as soft drinks, beer, pet food, and other perishable items. In order to ensure product safety and performance, the double seam between the can body and lid is a critical component of the package. Double-seaming is a method by which the flange of the can body and the curl of the end are folded over together such that the final joint is composed of five metal thicknesses. There are a number of design challenges involved with the art of double seaming, especially with the push to lightweight. Although the requirements vary by product, the typical beer package must be able to hold pressures in excess of 90psi. In addition, in production, double seaming is a high-speed operation with speeds as high as 3000 cans/minute on an 18-spindle seamer. For this high volume, low cost industry, understanding and optimizing the seaming process can advance the industry as well as help prevent various manufacturing problems that produce a poor seal between the two pieces of the can.To aid in understanding the mechanics of the can parts during double-seaming, a simulation procedure was developed and carried out on a 202 diameter beverage can and lid. Simulations were run with the explicit dynamics solver ABAQUS/Explicit using the continuum shell element technology available in the ABAQUS general purpose FEA program. The continuum shell is a shear-deformable shell element with the topology of an eight node brick. The element's formulation allows continuously varying, solution-dependent shell thickness and through-thickness pinching stress. One important advantage of using the continuum shell as opposed to a traditional shell element is that true contact interactions at the top and bottom surfaces of the can body and lid can be accurately modeled. With a conventional shell element, contact is performed at the

  4. [Grades evaluation of Phellodendri chinensis cortex pieces based on quality constant].

    Science.gov (United States)

    Deng, Zhe; Jiao, Meng-Jiao; Zhang, Jun; Zhang, Qing; Cui, Wen-Jin; Shen, Li; Cheng, Jin-Tang; Liu, An

    2017-09-01

    Quality constant is a comprehensive grades evaluation method for traditional Chinese medicine decoction pieces, which is better but based on traditional way. In this paper, a new grading mode for Phellodendri chinensis pieces was established based on quality constant evaluation method. The results showed that the range of relative quality constant for 15 batches of different samples was from 0.41 to 0.96. As customary, if these samples were divided into three grades: the relative quality constant shall be ≥0.77 for first grade; quality constant mode can be used to effectively grade the P. chinensis pieces in a scientific, reasonable, objective and specific way. Simultaneously, it provided a beneficial reference for grading cortex herbal pieces or medicines. Copyright© by the Chinese Pharmaceutical Association.

  5. NICHD Research Networks Help Piece Together the Puzzle of Polycystic Ovary Syndrome

    Science.gov (United States)

    ... research networks help piece together the puzzle of polycystic ovary syndrome Many people think that scientific progress is ... Consider, for example the puzzling disorder known as polycystic ovary syndrome (PCOS) . Women with this condition produce high ...

  6. Distance pieces for the mutual support of hexagonal fuel element boxes of a fast sodium-cooled breeder reactor

    International Nuclear Information System (INIS)

    Wild, E.

    1986-01-01

    All fuel elements are supported by distance pieces below and above the fuel zone. Each distance piece consists of two adjacent distance pieces of the same width and length, which are made of various materials. Stellite 6 with Inconel 718 or Hastelloy are particularly suitable as pairs of materials. These pairs of materials hardly tend to cold welding. (DG) [de

  7. Single-molecule tracking of small GTPase Rac1 uncovers spatial regulation of membrane translocation and mechanism for polarized signaling

    Science.gov (United States)

    Das, Sulagna; Yin, Taofei; Yang, Qingfen; Zhang, Jingqiao; Wu, Yi I.; Yu, Ji

    2015-01-01

    Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent of each other and what their respective roles are in polarization of Rac1 signaling. We designed a single-particle tracking (SPT) method to quantitatively analyze the kinetics of Rac1 membrane translocation in living cells. We found that the rate of Rac1 translocation was significantly elevated in protrusions during cell spreading on collagen. Furthermore, combining FRET sensor imaging with SPT measurements in the same cell, the recruitment of Rac1 was found to be polarized to an extent similar to that of the nucleotide exchange process. Statistical analysis of single-molecule trajectories and optogenetic manipulation of membrane lipids revealed that Rac1 membrane translocation precedes nucleotide exchange, and is governed primarily by interactions with phospholipids, particularly PI(3,4,5)P3, instead of protein factors. Overall, the study highlights the significance of membrane translocation in spatial Rac1 signaling, which is in addition to the traditional view focusing primarily on GEF distribution and exchange reaction. PMID:25561548

  8. The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-01-01

    The influence of composition on the tensile and creep strength of 001-line oriented nickel-base superalloy single crystals at temperatures near 1000 C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247. For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta-plus-W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels of gamma-prime volume fraction, gamma-gamma-prime lattice mismatch, and solid solution hardening.

  9. The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

    Science.gov (United States)

    Ali, Sajjad; Fu Liu, Tian; Lian, Zan; Li, Bo; Sheng Su, Dang

    2017-08-23

    The mechanism of CO oxidation by O 2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory. We determine that single Au atoms can be trapped effectively by the defects on SWCNTs. The defects on SWCNTs can enhance both the binding strength and catalytic activity of the supported single Au atom. Fundamental aspects such as adsorption energy and charge transfer are elucidated to analyze the adsorption properties of CO and O 2 and co-adsorption of CO and O 2 molecules. It is found that CO binds stronger than O 2 on Au supported SWCNT. We clearly demonstrate that the defected SWCNT surface promotes electron transfer from the supported single Au atom to O 2 molecules. On the other hand, this effect is weaker for pristine SWCNTs. It is observed that the high density of spin-polarized states are localized in the region of the Fermi level due to the strong interactions between Au (5d orbital) and the adjacent carbon (2p orbital) atoms, which influence the catalytic performance. In addition, we elucidate both the Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms of CO oxidation by O 2 . For the LH pathway, the barriers of the rate-limiting step are calculated to be 0.02 eV and 0.05 eV for Au/m-SWCNT and Au/di-SWCNT, respectively. To regenerate the active sites, an ER-like reaction occurs to form a second CO 2 molecule. The ER pathway is observed on Au/m-SWCNT, Au/SW-SWCNT and Au/SWCNT in which the Au/m-SWCNT has a smaller barrier. The comparison with a previous study (Lu et al., J. Phys. Chem. C, 2009, 113, 20156-20160.) indicates that the curvature effect of SWCNTs is important for the catalytic property of the supported single Au. Overall, Au/m-SWCNT is identified as the most active catalyst for CO oxidation compared to pristine SWCNT, SW-SWCNT and di-SWCNT. Our findings give a

  10. The kink-pair mechanism and low-temperature flow-stress behaviour of strontium titanate single crystals

    International Nuclear Information System (INIS)

    Castillo-Rodriguez, M.; Sigle, W.

    2011-01-01

    The mechanical behaviour of strontium titanate exhibits a remarkable behaviour at low temperature, in the so-called regime A, where the flow stress experiences two different temperature dependences separated by a noticeably abrupt drop in between. The dislocation microstructure was investigated and, by making adequate use of the kink-pair model, we interpret this behaviour as a transition from the short- to the long-segment limit of kink-pair formation. The fit parameters are found to be physically sound.

  11. Depressurization and boiling of a single magmatic fluid as a mechanism for tin-tungsten deposit formation

    OpenAIRE

    Maximilian Korges; Philipp Weis; Volker Lüders; Oscar Laurent

    2018-01-01

    Tin (Sn) and tungsten (W) mineralization are commonly associated with each other in relation to highly evolved granites, but economical ore grades are restricted to rare global occurrences and mineralization styles are highly variable, indicating different mechanisms for ore formation. The Sn-W Zinnwald deposit in the Erzgebirge (Germany and the Czech Republic) in the roof zone of a Variscan Li-F granite hosts two contrasting styles of mineralization: (1) cassiterite (Sn) in greisen bodies, a...

  12. An Automatic System of Testing the Best Stress of Installation for Semiconductor Refrigeration Piece

    Science.gov (United States)

    Chen, Hongyan; Song, Ping

    Concerning the problems of the impact on the factors of installation about semiconductor refrigeration piece are rarely studied in China and abroad, a reasonable structure of test device is designed, using stepper motor to test the temperature of the cold surface under different stress of installation to get the best stress of installation for the semiconductor refrigeration piece. Experiments shows that the system is of good noise immunity, high controlling and measuring precision.

  13. Piece rates and their effects on health and safety - a literature review.

    Science.gov (United States)

    Johansson, Bo; Rask, Kjell; Stenberg, Magnus

    2010-07-01

    The purpose of this study was to carry out a broad survey and analysis of relevant research articles about piece rate wages and their effects on health and safety that were published internationally until the fall of 2008. The aim was to summarize and describe the state of the art of the research in this field and if possible draw conclusions from the accumulated research results. A total of 75 research articles were examined extensively and 31 of these were found relevant and had sufficient quality to serve the purpose of this study. The findings of these relevant articles are summarized and analyzed in the survey. Since the late 1980s, there has been a change of research focus regarding piece rates and their effects on health and safety. More recent research shows a clear interest for health, musculoskeletal injuries, physical workload, pains and occupational injuries. The previous interest in risk behavior, security and accidents is still there, but no longer dominates the research scene. Although research is still sparse and fragmented, much of the accumulated knowledge about the effects of piece rate work tells us that piece rates in many situations have a negative effect on health and safety. The fact that 27 of the 31 studied articles found negative effects of piece rates on different aspects of health and safety does not prove causality, but together they give very strong support for the hypothesis that in most situations piece rates have negative effects on health and safety. In order to achieve better knowledge about the effects of piece rates in branches where piece rates are regarded problematic, further research is needed and such research has to be designed to meet the specific questions that are to be answered. Copyright 2010 Elsevier Ltd. All rights reserved.

  14. Application of gamma radiation to the nodes detection in Pinus Radiata (D.Don) wood pieces

    International Nuclear Information System (INIS)

    Morales, J.R.; Dinator, Maria I; Karsulovic C, Jose T.; Leon G, Adolfo

    1996-01-01

    Attenuation of 59.5 KeV photons provided by an Am-241 source, has been used to detect knots in lumber pieces from Pinus Radiata (D.Don). It is shown that the linear attenuation coefficient is a sensitive parameter to detect singularities in the structure of this material. The scanning of the piece provides profiles which define the position and extension of the singularity. (author)

  15. Nzikitanza – A piece on the resistance against the MUOS in Niscemi , Sicily

    Directory of Open Access Journals (Sweden)

    Marcello Messina

    2015-12-01

    Full Text Available Nzikitanza for accordion, violin, cello and tape was written in 2012 as a reflection on the deployment of Sicilian territory for NATO and US military operations. In particular, the piece was inspired by the then newly formed resistance committee against the MUOS in Niscemi. This brief commentary will illustrate a priori and a posteriori reflections on the status of the piece as a contribution to forms of antagonistic culture.

  16. Measurement of the mechanical properties of single Synechocystis sp. strain PCC6803 cells in different osmotic concentrations using a robot-integrated microfluidic chip.

    Science.gov (United States)

    Chang, Di; Sakuma, Shinya; Kera, Kota; Uozumi, Nobuyuki; Arai, Fumihito

    2018-03-23

    Synechocystis sp. strain PCC6803 (Synechocystis) is a model microorganism and its mechanosensitive (MS) channels play important roles in its osmoadaptation mechanism. When the osmotic concentration of the culture environment changes, the inner pressure of the cell also changes due to the transportation of water through ion channels. Because the tension in the cell membrane relates to the inner pressure, we expect that the response of the MS channels to an osmotic concentration change could be evaluated by measuring their mechanical properties. Here, we propose a system for the measurement of the mechanical properties of a single Synechocystis cell. We developed a robot-integrated microfluidic chip combined with optical tweezers. The chip has an external actuated pushing probe and a force sensor probe. A single cell was located between the tip of both probes using the optical tweezers and was then deformed using the probes. As a result, we could measure the force and deformation and compare the Young's moduli of two groups: a group of wild type cells and a group of mutant (genetically modified) cells with a defect in the MS channels, at three different osmotic concentrations. The results showed that the Young's modulus of each group changed according to the osmotic concentration, while changes in cell size were too small to be detected. These results confirmed that the proposed evaluation method provides an understanding of the physiological function of MS channels for keeping the cell integrity of microorganisms when the cells are exposed to different external osmotic changes.

  17. Pay Matters: The Piece Rate and Health in the Developing World.

    Science.gov (United States)

    Davis, Mary E

    Piece rate pay remains a common form of compensation in developing-world industries. While the piece rate may boost productivity, it has been shown to have unintended consequences for occupational safety and health, including increased accident and injury risk. This paper explores the relationship between worker pay and physical and emotional health, and questions the modern day business case for piece rate pay in the developing world. The relationship between piece rate and self-reported measures of physical and emotional health is estimated using a large survey of garment workers in 109 Vietnamese factories between 2010 and 2014. A random effects logit model controls for factory and year, predicting worker health as a function of pay type, demographics, and factory characteristics. Workers paid by the piece report worse physical and emotional health than workers paid by the hour (OR = 1.38-1.81). Wage incentives provide the most consistently significant evidence of all demographic and factory-level variables, including the factory's own performance on occupational safety and health compliance measures. These results highlight the importance of how workers are paid to understanding the variability in worker health outcomes. More research is needed to better understand the business case supporting the continued use of piece rate pay in the developing world. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

  18. [Application of relative quality constant in grades evaluation of Glycyrrizae Radix et Rhizome pieces].

    Science.gov (United States)

    Deng, Zhe; Jiao, Meng-Jiao; Zhang, Jun; Xian, Jing; Zhang, Qing; Chen, Chang; Wang, Yue-Sheng; Liu, An

    2017-07-01

    Quality constant evaluation is a comprehensive method for grades evaluation of traditional Chinese medicine pieces, but when it comes to Glycyrrizae Radix et Rhizome pieces, grades evaluation is diverged due to significant difference in contents of liquiritin and glycyrrhizic acid and unreasonable weight of index. To solve this problem, we have established a relative quality constant method in this paper to evaluate grades of Glycyrrizae Radix et Rhizome pieces. Twenty-nine batches of different quality samples were collected and tested, and finally, 17 batches of them were chosen as researcher objects. The results revealed that the range of the relative quality constant of these samples was from 1.78 to 11.49. When Glycyrrizae Radix et Rhizome pieces are divided into three grades: the relative quality constant of first grade is greater than or equal to 9.19; the second grade is greater than or equal to 5.75 but less than 9.19; while the third grade is less than 5.75. This research indicates that relative quality constant can divide the grades of herbal pieces in a scientific, reasonable, objective and specific way and remedy the shortage of quality constant perfectly. It provides a novel mode for grading pieces of Chinese medicine that contains multi-target ingredients. Copyright© by the Chinese Pharmaceutical Association.

  19. Single nanowire electrode electrochemistry of silicon anode by in situ atomic force microscopy: solid electrolyte interphase growth and mechanical properties.

    Science.gov (United States)

    Liu, Xing-Rui; Deng, Xin; Liu, Ran-Ran; Yan, Hui-Juan; Guo, Yu-Guo; Wang, Dong; Wan, Li-Jun

    2014-11-26

    Silicon nanowires (SiNWs) have attracted great attention as promising anode materials for lithium ion batteries (LIBs) on account of their high capacity and improved cyclability compared with bulk silicon. The interface behavior, especially the solid electrolyte interphase (SEI), plays a significant role in the performance and stability of the electrodes. We report herein an in situ single nanowire atomic force microscopy (AFM) method to investigate the interface electrochemistry of silicon nanowire (SiNW) electrode. The morphology and Young's modulus of the individual SiNW anode surface during the SEI growth were quantitatively tracked. Three distinct stages of the SEI formation on the SiNW anode were observed. On the basis of the potential-dependent morphology and Young's modulus evolution of SEI, a mixture-packing structural model was proposed for the SEI film on SiNW anode.

  20. Dominant pinning mechanisms in YBa2Cu3O7-x films on single and polycrystalline yttria stabilized zirconia substrates

    Science.gov (United States)

    Harshavardhan, K. S.; Rajeswari, M.; Hwang, D. M.; Chen, C. Y.; Sands, T.; Venkatesan, T.; Tkaczyk, J. E.; Lay, K. W.; Safari, A.

    1992-04-01

    Critical-current densities have been measured in YBa2Cu3O7-x films deposited on (100) yttria stabilized zirconia (YSZ) and polycrystalline YSZ substrates as a function of temperature (4.5-88 K), magnetic field (0-1 T) and orientation relative to the applied field. The results indicate that in films on polycrystalline substrates, surface and interface pinning play a dominant role at high temperatures. In films on (100) YSZ, pinning is mainly due to intrinsic layer pinning as well as extrinsic pinning associated with the interaction of the fluxoids with point defects and low energy planar (2D) boundaries. The differences are attributed to the intrinsic rigidity of single fluxoids which is reduced in films on polycrystalline substrates thereby weakening the intrinsic layer pinning.

  1. Promoting mechanism of N-doped single-walled carbon nanotubes for O2 dissociation and SO2 oxidation

    Science.gov (United States)

    Chen, Yanqiu; Yin, Shi; Chen, Yang; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

    2018-03-01

    Although heteroatom doping in carbon based catalysts have recently received intensive attentions, the role of the intrinsically porous structure of practical carbon materials and their potential synergy with doping atoms are still unclear. To investigate the complex effects, a range of N-doped single-walled carbon nanotubes (SWCNTs) were used to investigate their potential use for O2 dissociation and the subsequent SO2 oxidation using density functional theory. It is found that graphite N doping can synergize with the outer surface of SWCNTs to facilitate the dissociation of O2. The barrier for the dissociation on dual graphite N-doped SWCNT-(8, 8) is as low as 0.3 eV, and the subsequent SO2 oxidation is thermodynamically favorable and kinetically feasible. These results spotlight on developing promising carboncatalyst via utilization of porous gemometry and heteroatom-doping of carbon materials simultaneously.

  2. Emergence of cytotoxic resistance in cancer cell populations: Single-cell mechanisms and population-level consequences

    International Nuclear Information System (INIS)

    Lorenzi, Tommaso; Chisholm, Rebecca H.; Lorz, Alexander; Neves de Almeida, Luís; Clairambault, Jean; Larsen, Annette K.; Escargueil, Alexandre

    2016-01-01

    We formulate an individual-based model and a population model of phenotypic evolution, under cytotoxic drugs, in a cancer cell population structured by the expression levels of survival-potential and proliferation-potential. We apply these models to a recently studied experimental system. Our results suggest that mechanisms based on fundamental laws of biology can reversibly push an actively-proliferating, and drug-sensitive, cell population to transition into a weakly-proliferative and drug-tolerant state, which will eventually facilitate the emergence of more potent, proliferating and drug-tolerant cells.

  3. Emergence of cytotoxic resistance in cancer cell populations: Single-cell mechanisms and population-level consequences

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzi, Tommaso [Centre de Mathématiques et de Leurs Applications, ENS Cachan, CNRS, Cachan 94230 Cedex, France & INRIA-Paris-Rocquencourt, MAMBA Team, Domaine de Voluceau, BP105, 78153 Le Chesnay Cedex (France); Chisholm, Rebecca H. [School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052 (Australia); Lorz, Alexander; Neves de Almeida, Luís; Clairambault, Jean [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); CNRS, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); INRIA-Paris-Rocquencourt, MAMBA Team, Domaine de Voluceau, BP105, 78153 Le Chesnay Cedex (France); Larsen, Annette K.; Escargueil, Alexandre [Sorbonne Universités, UPMC Univ Paris 06, F-75005, Paris (France); INSERM, UMR-S 938, Laboratory of “Cancer Biology and Therapeutics”, F-75012, Paris (France)

    2016-06-08

    We formulate an individual-based model and a population model of phenotypic evolution, under cytotoxic drugs, in a cancer cell population structured by the expression levels of survival-potential and proliferation-potential. We apply these models to a recently studied experimental system. Our results suggest that mechanisms based on fundamental laws of biology can reversibly push an actively-proliferating, and drug-sensitive, cell population to transition into a weakly-proliferative and drug-tolerant state, which will eventually facilitate the emergence of more potent, proliferating and drug-tolerant cells.

  4. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong

    2009-02-05

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed in comparison with the growth of ZnO nanowires. The ZnO mesoporous film was successfully applied as a gas sensor. The fabrication and growth analysis of the mesoporous ZnO thin film gi ve general guidance for the controlled growth of nanostructures. It also pro vides a unique structure with a superhigh surface-to-volume ratio for surface-related applications. © 2009 American Chemical Society.

  5. Mechanical Control of Whole Body Shape by a Single Cuticular Protein Obstructor-E in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Reiko Tajiri

    2017-01-01

    Full Text Available Body shapes are much more variable than body plans. One way to alter body shapes independently of body plans would be to mechanically deform bodies. To what extent body shapes are regulated physically, or molecules involved in physical control of morphogenesis, remain elusive. During fly metamorphosis, the cuticle (exoskeleton covering the larval body contracts longitudinally and expands laterally to become the ellipsoidal pupal case (puparium. Here we show that Drosophila melanogaster Obstructor-E (Obst-E is a protein constituent of the larval cuticle that confers the oriented contractility/expandability. In the absence of obst-E function, the larval cuticle fails to undergo metamorphic shape change and finally becomes a twiggy puparium. We present results indicating that Obst-E regulates the arrangement of chitin, a long-chain polysaccharide and a central component of the insect cuticle, and directs the formation of supracellular ridges on the larval cuticle. We further show that Obst-E is locally required for the oriented shape change of the cuticle during metamorphosis, which is associated with changes in the morphology of those ridges. Thus, Obst-E dramatically affects the body shape in a direct, physical manner by controlling the mechanical property of the exoskeleton.

  6. Pieced Together: Collage as an Artist's Method for Interdisciplinary Research

    Directory of Open Access Journals (Sweden)

    Kathleen Vaughan

    2005-03-01

    Full Text Available As a visual artist undertaking doctoral studies in education, the author required a research method that integrated her studio practice into her research process, giving equal weight to the visual and the linguistic. Her process of finding such a method is outlined in this article, which touches on arts-based research and practice-led research, and her ultimate approach of choice, collage. Collage, a versatile art form that accommodates multiple texts and visuals in a single work, has been proposed as a model for a “borderlands epistemology”: one that values multiple distinctive understandings and that deliberately incorporates nondominant modes of knowing, such as visual arts. As such, collage is particularly suited to a feminist, postmodern, postcolonial inquiry. This article offers a preliminary theorizing of collage as a method and is illustrated with images from the author's research/visual practice.

  7. Analysis of mechanical properties of N2in situ doped polycrystalline 3C-SiC thin films by chemical vapor deposition using single-precursor hexamethyildisilane

    International Nuclear Information System (INIS)

    Kim, Kang-San; Han, Ki-Bong; Chung, Gwiy-Sang

    2010-01-01

    This paper describes the mechanical properties of poly (polycrystalline) 3C-SiC thin films with N 2 in situ doping. In this work, in situ doped poly 3C-SiC film was deposited by using the atmospheric pressure chemical vapor deposition (APCVD) method at 1200 deg. C using single-precursor hexamethyildisilane: Si 2 (CH 3 ) 6 (HMDS) as Si and C precursors, and 0∼100 sccm N 2 as the dopant source gas. The mechanical properties of doped poly 3C-SiC thin films were measured by nano-indentation. Young's modulus and hardness were measured to be 285 and 35 GPa at 0 sccm N 2 , respectively. Young's modulus and hardness decreased with increasing N 2 flow rate. Surface morphology was evaluated by atomic force microscopy (AFM) according to N 2 flow rate.

  8. PUMA: a puzzle piece in chloroquine's antimelanoma activity.

    Science.gov (United States)

    Amaravadi, Ravi K

    2013-09-01

    Chloroquine (CQ) can induce cell death in a subset of cancer cell lines, and some melanoma cell lines are quite susceptible. Although it is well known that CQ impairs lysosomal function and can serve as an autophagy inhibitor, the molecular target of CQ and the subsequent cascade of events that lead to cell death are not fully understood. Recent evidence indicates that in melanoma cell lines, CQ induces apoptosis by preventing degradation of the pro-apoptotic BH3-only protein p53-upregulated modulator of apoptosis. This finding adds to the unfolding story of CQ's mechanism of action as a cancer therapeutic agent.

  9. PUMA: a puzzle piece in chloroquine’s antimelanoma activity

    Science.gov (United States)

    Amaravadi, Ravi K.

    2013-01-01

    Chloroquine can induce cell death in a subset of cancer cell lines, and some melanoma cell lines are quite susceptible. While it is well known that chloroquine impairs lysosomal function and can serve as an autophagy inhibitor, the molecular target of chloroquine and the subsequent cascade of events that leads to cell death are not fully understood. Recent evidence indicates that in melanoma cell lines, chloroquine induces apoptosis by preventing degradation of the pro-apoptotic BH3-only protein PUMA. This finding adds to the unfolding story of chloroquine’s mechanism of action as a cancer therapeutic agent. PMID:23949767

  10. A microfluidic-enabled mechanical microcompressor for the immobilization of live single- and multi-cellular specimens.

    Science.gov (United States)

    Yan, Yingjun; Jiang, Liwei; Aufderheide, Karl J; Wright, Gus A; Terekhov, Alexander; Costa, Lino; Qin, Kevin; McCleery, W Tyler; Fellenstein, John J; Ustione, Alessandro; Robertson, J Brian; Johnson, Carl Hirschie; Piston, David W; Hutson, M Shane; Wikswo, John P; Hofmeister, William; Janetopoulos, Chris

    2014-02-01

    A microcompressor is a precision mechanical device that flattens and immobilizes living cells and small organisms for optical microscopy, allowing enhanced visualization of sub-cellular structures and organelles. We have developed an easily fabricated device, which can be equipped with microfluidics, permitting the addition of media or chemicals during observation. This device can be used on both upright and inverted microscopes. The apparatus permits micrometer precision flattening for nondestructive immobilization of specimens as small as a bacterium, while also accommodating larger specimens, such as Caenorhabditis elegans, for long-term observations. The compressor mount is removable and allows easy specimen addition and recovery for later observation. Several customized specimen beds can be incorporated into the base. To demonstrate the capabilities of the device, we have imaged numerous cellular events in several protozoan species, in yeast cells, and in Drosophila melanogaster embryos. We have been able to document previously unreported events, and also perform photobleaching experiments, in conjugating Tetrahymena thermophila.

  11. Single-Nucleotide Mutations in Reveal Novel Functions and Regulatory Mechanisms of the Fragile X Syndrome Protein FMRP

    Directory of Open Access Journals (Sweden)

    Joshua A. Suhl

    2015-01-01

    Full Text Available Fragile X syndrome is a monogenic disorder and a common cause of intellectual disability. Despite nearly 25 years of research on FMR1, the gene underlying the syndrome, very few pathological mutations other than the typical CGG-repeat expansion have been reported. This is in contrast to other X-linked, monogenic, intellectual disability disorders, such as Rett syndrome, where many point mutations have been validated as causative of the disorder. As technology has improved and significantly driven down the cost of sequencing, allowing for whole genes to be sequenced with relative ease, in-depth sequencing studies on FMR1 have recently been performed. These studies have led to the identification of novel variants in FMR1 , where some of which have been functionally evaluated and are likely pathogenic. In this review, we discuss recently identified FMR1 variants, the ways these novel variants cause dysfunction, and how they reveal new regulatory mechanisms and functionalities of the gene.

  12. Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy

    Science.gov (United States)

    Kuppan, Saravanan; Xu, Yahong; Liu, Yijin; Chen, Guoying

    2017-02-01

    Understanding the reaction pathway and kinetics of solid-state phase transformation is critical in designing advanced electrode materials with better performance and stability. Despite the first-order phase transition with a large lattice mismatch between the involved phases, spinel LiMn1.5Ni0.5O4 is capable of fast rate even at large particle size, presenting an enigma yet to be understood. The present study uses advanced two-dimensional and three-dimensional nano-tomography on a series of well-formed LixMn1.5Ni0.5O4 (0growth process instead of a shrinking-core or a particle-by-particle process. Superior kinetics of (100) facets at the vertices of truncated octahedral particles promote preferential delithiation, whereas the observation of strain-induced cracking suggests mechanical degradation in the material.

  13. AN INVESTIGATION INTO THE MECHANICS OF SINGLE CRYSTAL TURBINE BLADES WITH A VIEW TOWARDS ENHANCING GAS TURBINE EFFICIENCY

    Energy Technology Data Exchange (ETDEWEB)

    K.R. Rajagopal; I.J. Rao

    2006-05-05

    The demand for increased efficiency of gas turbines used in power generation and aircraft applications has fueled research into advanced materials for gas turbine blades that can withstand higher temperatures in that they have excellent resistance to creep. The term ''Superalloys'' describes a group of alloys developed for applications that require high performance at elevated temperatures. Superalloys have a load bearing capacity up to 0.9 times their melting temperature. The objective of the investigation was to develop a thermodynamic model that can be used to describe the response of single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model. Having developed the model, its efficacy was to be tested by corroborating the predictions of the model with available experimental data. Such a model was developed and it is implemented in the finite element software ABAQUS/STANDARD through a user subroutine (UMAT) so that the model can be used in realistic geometries that correspond to turbine blades.

  14. Synthesis, growth, optical and anisotropic mechanical behaviour of organic nonlinear optical imidazolium 2-chloro-4-nitrobenzoate single crystals

    Science.gov (United States)

    Krishnakumar, Varadharajan; Jayaprakash, Jeyaram; Boobas, Singaram; Komathi, Muniraj

    2016-10-01

    The title compound, imidazolium 2-chloro-4-nitrobenzoate (I2C4NB), has been synthesized and optical quality single crystals were grown with a dimension of 4 × 2 × 1 mm3 using an ethanol and acetone (1:1) mixed solvent by slow evaporation solution growth technique. The powder XRD analysis confirmed the crystal structure and found that it is crystallized in the non-centrosymmetric space group P21 with the monoclinic system. The symmetries of molecular vibrations were confirmed by FT-IR spectrum. The CHN(S) analysis confirmed the stoichiometric composition of the grown crystal. It also exhibits a good transparency in the entire visible region (300-800nm) and it was thermally stable up to 131.1 °C. The microhardness measurement shows the anisotropic nature of I2C4NB and also that it belongs to a soft material category. Photoconductivity studies reveal a linear increase of the photocurrent with respect to the applied electric field. HOMO LUMO studies were carried out for the crystal. The second harmonic generation test by the Kurtz powder method shows that the crystal exhibits phase matching and a conversion efficiency which is 2 times that of KDP.

  15. Enhanced mechanical properties of single walled carbon nanotube-borosilicate glass composite due to cushioning effect and localized plastic flow

    Directory of Open Access Journals (Sweden)

    Sujan Ghosh

    2011-12-01

    Full Text Available A borosilicate glass composite has been fabricated incorporating Single Wall Carbon Nanotubes (SWCNT in the glass matrix by melt-quench technique. Hardness and the fracture toughness of the composite, were found to increase moderately with respect to the base glass. Interestingly one can observe accumulation of SWCNT bundles around the crack zone though no such accumulation was observed in the crack free indentation zone. The enhanced hardness of the composite was discussed by correlating the cushioning as well as toughening behavior of the agglomerated SWCNT bundles. On the other hand enhanced plastic flow was proposed to be the prime reason for the accumulation of SWCNT bundles around the crack, which increases the toughness of the composite by reducing the crack length. Moreover to ascertain the enhanced plasticity of the composite than that of the glass we calculated the recovery resistance of glass and the composite where recovery resistance of composite was found to be higher than that of the glass.

  16. Effect of single and multi-wall carbon nanotubes on the mechanical properties of Gd-123 superconducting phase

    Science.gov (United States)

    Anas, M.; Ebrahim, Shaker; Eldeen, I. G.; Awad, R.; Abou-Aly, A. I.

    2017-10-01

    The influence of single wall carbon nanotubes SWCNTs and multi wall carbon nanotubes MWCNTs on Vickers microhardness of Gd-123 superconducting phase is studied. Samples of type (SWCNTs)x and (MWCNTs)xGdBa2Cu3O7-δ, composite where, 0.0 ≤ x ≤ 0.1 wt.%, are prepared by solid-state reaction technique. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). Moreover the samples are examined by measuring electrical resistivity and Vickers microhardness. The obtained results showed an enhancement in the phase formation and grains connectivity up to 0.06 and 0.08 wt.% for SWCNTs and MWCNTs added samples, respectively. Likewise the superconducting transition temperature Tc was improved at a low content of CNTs but it suppressed for higher concentrations. In addition, the analysis of Vickers microhardness measurements suggests that the most suitable model that describes the behavior of our sample is proportional specimen resistance PSR model.

  17. Different mechanisms of radiation-induced loss of heterozygosity in two human lymphoid cell lines from a single donor

    Science.gov (United States)

    Wiese, C.; Gauny, S. S.; Liu, W. C.; Cherbonnel-Lasserre, C. L.; Kronenberg, A.

    2001-01-01

    Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis combined with microsatellite marker analysis showed that the increase in TK1 mutagenesis in WTK1 cells could be attributed, in part, to mitotic recombination. The microsatellite marker analysis over a 64-cM region on chromosome 17q indicated that the recombinational events could initiate at different positions between the TK1 locus and the centromere. Virtually all of the recombinational LOH events extended beyond the TK1 locus to the most telomeric marker. In general, longer LOH tracts were observed in mutants from WTK1 cells than in mutants from TK6 cells. Taken together, the results demonstrate that the incidence of radi-ation-induced mutations is dependent on the genetic background of the cell at risk, on the locus examined, and on the mechanisms for mutation available at the locus of interest.

  18. Mechanical performance of a screw-type veterinary suture anchor subjected to single load to failure and cyclic loads.

    Science.gov (United States)

    Balara, Jason M; McCarthy, Robert J; Boudrieau, Randy J; Kraus, Karl H

    2004-01-01

    To characterize the mechanical performance of a veterinary bone anchor under static and cyclic loads. Mechanical testing study. Cadaveric canine humeri. Humeri (6 pairs) were collected from skeletally mature dogs (mean [+/-SD] age, 17.2+/-2.1 months; weight, 20.8+/-1.5 kg). Bone anchors were inserted in the proximal metaphysis using nylon, and were longitudinally extracted. For the opposite humerus, anchors were subjected to longitudinal cyclic load (50% of the load at failure of their pair) for 1200 cycles then longitudinally loaded to failure. Anchors were then installed in a similar and adjacent area of these 2(nd) humeri with nylon and cyclically tested perpendicular to the axis of anchor insertion (100% of the longitudinal holding power of their pair) for 1200 cycles, then perpendicularly loaded to failure. Paired t-tests were used to compare holding power before and after longitudinal cyclic testing. Longitudinal holding power of the screw-type anchor in the proximal humerus was 385+/-30 N. Anchor pullout was the only mode of failure. Anchors in the paired humeri did not fail after 1200 cycles of 50% longitudinal loading, and post-cycle holding strength was not different (335+/-87 N; P=.32). Perpendicularly loaded anchors did not fail after 1200 cycles of 100% of opposite longitudinal holding strength, and had post-cycle perpendicular holding strengths of 514+/-72 N. Suture breakage was the mode of failure. Bone anchor holding strength is dependent on orientation of suture load. Screw-type bone anchor holding strength was not affected by longitudinal cyclic loading, and holding strengths of approximately 385 N can be expected in metaphyseal bone of large-breed mature dogs. Perpendicularly loaded anchors have higher failure loads, and holding strength of approximately 514 N can be expected in metaphyseal bone of the proximal humerus.

  19. Molecular beam study of the mechanism of catalyzed hydrogen--deuterium exchange on platinum single crystal surfaces

    International Nuclear Information System (INIS)

    Bernasek, S.L.; Somorjai, G.A.

    1975-01-01

    The hydrogen--deuterium exchange reaction was studied by molecular beam scattering on low and high Miller index crystal faces of platinum in the surface temperature range of 300--1300degreeK. Under the condition of the experiments which put strict limitation on the residence time of the detected molecules, the reaction product, HD, was readily detectable from the high Miller index, stepped surfaces (integrated reaction probability, defined as total desorbed HD flux divided by D 2 flux, is approx.10/sup -1/) while HD formation was below the limit of detectability on the Pt(111) low Miller index surface (reaction probability 2 beam pressure and half-order in H 2 background pressure. The absence of beam kinetic energy dependence of the rate indicates that the molecular adsorption does not require activation energy. The surface is able to store a sufficiently large concentration of atoms which react with the molecules by a two-branch mechanism. The rate constants for this two-branch mechanism were determined under conditions of constant H atom coverage, reducing the bimolecular reaction to a pseudo-first-order reaction. At lower temperatures ( 1 = (2plus-or-minus1) times10 5 exp(-4.5plus-or-minus0.5 kcal/RT) sec/sup -1/. The rate determining step appears to be the diffusion of the D 2 molecule on the surface to a step site where HD is formed via a three-center (atom--molecule) reaction, or via a two-center (atom--atom) reaction subsequent to D 2 dissociation at the step. At higher temperatures (>600degreeK) the reaction between an adsorbed H atom and an incident D 2 gas molecule competes with the low temperature branch. The rate constant for this branch is k 2 = (1plus-or-minus2) times10 2 exp(-0.6plus-or-minus0.3 kcal/RT) sec/sup -1/

  20. Altered lower extremity joint mechanics occur during the star excursion balance test and single leg hop after ACL-reconstruction in a collegiate athlete.

    Science.gov (United States)

    Samaan, Michael A; Ringleb, Stacie I; Bawab, Sebastian Y; Greska, Eric K; Weinhandl, Joshua T

    2018-03-15

    The effects of ACL-reconstruction on lower extremity joint mechanics during performance of the Star Excursion Balance Test (SEBT) and Single Leg Hop (SLH) are limited. The purpose of this study was to determine if altered lower extremity mechanics occur during the SEBT and SLH after ACL-reconstruction. One female Division I collegiate athlete performed the SEBT and SLH tasks, bilaterally, both before ACL injury and 27 months after ACL-reconstruction. Maximal reach, hop distances, lower extremity joint kinematics and moments were compared between both time points. Musculoskeletal simulations were used to assess muscle force production during the SEBT and SLH at both time points. Compared to the pre-injury time point, SEBT reach distances were similar in both limbs after ACL-reconstruction except for the max anterior reach distance in the ipsilateral limb. The athlete demonstrated similar hop distances, bilaterally, after ACL-reconstruction compared to the pre-injury time point. Despite normal functional performance during the SEBT and SLH, the athlete exhibited altered lower extremity joint mechanics during both of these tasks. These results suggest that measuring the maximal reach and hop distances for these tasks, in combination with an analysis of the lower extremity joint mechanics that occur after ACL-reconstruction, may help clinicians and researchers to better understand the effects of ACL-reconstruction on the neuromuscular system during the SEBT and SLH.