Science.gov

Sample records for a-150 plastic kerma

  1. Filament Winding of a Ship Hull. A Study of the Design of a 30 Ft. Filament Wound Model of a 150 Ft. GRP (Glass Reinforced Plastic) Ship.

    DTIC Science & Technology

    1983-10-01

    by block number) Naval Ship Structures; Composites . Glass Reinforced Plastics, Filament Winding, Minesweepers. 20. ABSTRACT (Continue on reverse side...associated with this method of manufacturing a ship hull out of Glass Reinforced Plastic (GRP). Winding machine and man- drel concepts were reviewed... machine and mandrel concepts were reviewed, as well as the structural requirements and possible materials. A design of a 1/5th scale (30 ft) model

  2. Remarks on KERMA Factors in ACE files

    NASA Astrophysics Data System (ADS)

    Konno, C.; Ochiai, K.; Takakura, K.; Sato, S.

    2014-04-01

    Some neutron KERMA factors in ACE files are negative and extremely large if nuclear data libraries do not keep energy-balance. The status of neutron KERMA factors in the official ACE file of ENDF/B-VII.1 is examined. As a result, it is found out that neutron KERMA factors of nuclei more than 200 in ENDF/B-VII.1 have some problems. Effects of the inadequate KERMA factor are also investigated, which are large for neutron heat while those are small for total (neutron + gamma) heat. Users who use only neutron KERMA factors should check if the factors are adequate or not before they use the factors.

  3. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    SciTech Connect

    Carl, W. F.

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  4. Nuclear Data Sheets for A=150

    SciTech Connect

    Basu, S.K.; Sonzogni, A.A.

    The experimental results from the various reaction and decay studies leading to nuclides in the A=150 mass chain have been reviewed. These data are summarized and presented, together with the adopted level schemes and properties, for the nuclides from Cs(Z=55) through Lu(Z=71). This evaluation replaces the previous evaluation by E. der Mateosian and J. K. Tuli (1995De28), which appeared in Nuclear Data Sheets 75, 827 (1995)

  5. Nuclear Data Sheets for A=150

    NASA Astrophysics Data System (ADS)

    Basu, S. K.; Sonzogni, A. A.

    2013-04-01

    The experimental results from the various reaction and decay studies leading to nuclides in the A=150 mass chain have been reviewed. These data are summarized and presented, together with the adopted level schemes and properties, for the nuclides from Cs(Z=55) through Lu(Z=71). This evaluation replaces the previous evaluation by E. der Mateosian and J. K. Tuli (1995De28), which appeared in Nuclear Data Sheets 75, 827 (1995).

  6. Evaluation of entrance surface air kerma in pediatric chest radiography

    NASA Astrophysics Data System (ADS)

    Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

    2014-11-01

    The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior-posterior (AP) and posterior-anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0-1 y, 1-5 y, 5-10 y, and 10-15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels.

  7. Comparison of the NIST and ENEA air kerma standards

    SciTech Connect

    Laitano, R.F.; Toni, M.P.; Lamperti, P.J.

    1998-07-01

    A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuov Tecnologie l`Energia e l`Ambiente (ENEA) air kerma standards for medium energy x rays and {sup 60}Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with {sup 60}Co gamma radiation. The transfer chamber calibration factorsmore » obtained at the NIST and at the ENEA agreed with one another to 0.03% for {sup 60}Co gamma radiation and between 0.1% to 0.8% for the medium energy x-ray beam codes.« less

  8. Comparison of the NIST and ENEA Air Kerma Standards

    PubMed Central

    Laitano, R. F.; Lamperti, P. J.; Toni, M. P.

    1998-01-01

    A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuove Tecnologie l’Energia e l’Ambiente (ENEA) air kerma standards for medium energy x rays and 60Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with 60Co gamma radiation. The transfer chamber calibration factors obtained at the NIST and at the ENEA agreed with one another to 0.03 % for 60Co gamma radiation and between 0.1 % to 0.8 % for the medium energy x-ray beam codes. PMID:28009356

  9. Simulation evaluation of NIST air-kerma rate calibration standard for electronic brachytherapy.

    PubMed

    Hiatt, Jessica R; Rivard, Mark J; Hughes, H Grady

    2016-03-01

    Dosimetry for the model S700 50 kV electronic brachytherapy (eBT) source (Xoft, Inc., a subsidiary of iCAD, San Jose, CA) was simulated using Monte Carlo (MC) methods by Rivard et al. ["Calculated and measured brachytherapy dosimetry parameters in water for the Xoft Axxent x-ray source: An electronic brachytherapy source," Med. Phys. 33, 4020-4032 (2006)] and recently by Hiatt et al. ["A revised dosimetric characterization of the model S700 electronic brachytherapy source containing an anode-centering plastic insert and other components not included in the 2006 model," Med. Phys. 42, 2764-2776 (2015)] with improved geometric characterization. While these studies examined the dose distribution in water, there have not previously been reports of the eBT source calibration methods beyond that recently reported by Seltzer et al. ["New national air-kerma standard for low-energy electronic brachytherapy sources," J. Res. Natl. Inst. Stand. Technol. 119, 554-574 (2014)]. Therefore, the motivation for the current study was to provide an independent determination of air-kerma rate at 50 cm in air K̇air(d=50 cm) using MC methods for the model S700 eBT source. Using CAD information provided by the vendor and disassembled sources, an MC model was created for the S700 eBT source. Simulations were run using the mcnp6 radiation transport code for the NIST Lamperti air ionization chamber according to specifications by Boutillon et al. ["Comparison of exposure standards in the 10-50 kV x-ray region," Metrologia 5, 1-11 (1969)], in air without the Lamperti chamber, and in vacuum without the Lamperti chamber. K̇air(d=50 cm) was determined using the *F4 tally with NIST values for the mass energy-absorption coefficients for air. Photon spectra were evaluated over 2 π azimuthal sampling for polar angles of 0° ≤ θ ≤ 180° every 1°. Volume averaging was averted through tight radial binning. Photon energy spectra were determined over all polar angles in both air and vacuum using

  10. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media.

    PubMed

    Kumar, Sudhir; Nahum, Alan E

    2016-02-07

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of 'secondary bremsstrahlung' along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV 'clinical' radiotherapy qualities. Concerning depth-dependence, the 'area under the kerma, K, curve' exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the 'double counting' of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma 'liberated' in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this 'violation' amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a 'clinical' 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm−2 for both very high and very low charged-particle transport cut-offs reveals the considerable

  11. Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

    PubMed Central

    2014-01-01

    This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

  12. Development of a phantom and a methodology for evaluation of depth kerma and kerma index for dental cone beam computed tomography.

    PubMed

    Batista, W O; Navarro, M V T; Maia, A F

    2013-12-01

    Basically, all modalities of diagnostic radiology require phantoms suitable for dosimetric evaluations. New technologies frequently arise unaccompanied of tools for dosimetric evaluations and quality control. In this study, a low-cost phantom and a consequent proposed methodology for dosimetric evaluations in cone beam computed tomography (CBCT) were presented. The developed phantom has typical dimensions of the human face, was built in polymethyl methacrylate and filled with water. Three devices with different technological concepts were evaluated and a proposed index, kerma index-height product (PKIH), was defined as an option to the use of air kerma-area product. The results of this study show relatively uniform kerma profiles for scanners with field of views (FOVs) of large diameters and non-uniform for FOVs of small diameters. With regard to the values obtained for the kerma indexes, much higher values were found for the equipment FOVs with small diameter compared with the values of the two other equipment that have larger diameters. The results indicate that (1) there is a need for special phantoms for use in CBCT, (2) the use of P(KA) in the evaluation of protocols on different equipment can lead to false interpretations and (3) the new index is a suitable alternative for the use of P(KA) in CBCT.

  13. The IPEM code of practice for determination of the reference air kerma rate for HDR 192Ir brachytherapy sources based on the NPL air kerma standard

    NASA Astrophysics Data System (ADS)

    Bidmead, A. M.; Sander, T.; Locks, S. M.; Lee, C. D.; Aird, E. G. A.; Nutbrown, R. F.; Flynn, A.

    2010-06-01

    This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR 192Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR 192Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an 192Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, \\dot K_R (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, SK (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL 192Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques.

  14. Comparison of the NIST and BIPM Medium-Energy X-Ray Air-Kerma Measurements

    PubMed Central

    Burns, D. T.; O’Brien, M.; Lamperti, P.; Boutillon, M.

    2003-01-01

    The air-kerma standards used for the measurement of medium-energy x rays were compared at the National Institute of Standards and Technology (NIST) and at the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and two NIST reference-class transfer ionization standards. Reference beam qualities in the range from 60 kV to 300 kV were used. The results show the standards to be in agreement within the combined standard uncertainty of the comparison of 0.35 %. PMID:27413616

  15. Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures

    NASA Astrophysics Data System (ADS)

    Vijayan, Sarath; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

    2016-03-01

    The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

  16. Seasonal variation of air kerma in the "Vulcano Porto" area (Aeolian Islands, Italy).

    PubMed

    Bellia, S; Basile, S; Brai, M; Hauser, S; Puccio, P; Rizzo, S

    2001-04-01

    Air kerma was measured in the "Vulcano Porto" area of the Vulcano Island, belonging to the Aeolian Islands, in the Mediterranean Sea. Measurements were carried out using thermoluminescence dosimeters. The relationship between observed dose values and source lithology has been assessed. Data show a seasonal variation due to weather conditions but also probably related to features of the soils, making the variation more evident.

  17. Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast.

    PubMed

    Gonçalves, Andréa; Rollo, João Manuel Domingos de Almeida; Gonçalves, Marcelo; Haiter Neto, Francisco; Bóscolo, Frab Norberto

    2004-01-01

    This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and were made on mandible phantom and on step-wedge. Depending on the thickness of aluminum-copper alloy filtration, the beam could be hardened and filtrated. The use of the aluminum-copper alloy filter resulted in reductions in air kerma rate from 8.40% to 47.33%, and indicated the same image contrast when compared to aluminum filtration. Aluminum-copper alloy filtration may be considered a good alternative to aluminum filtration.

  18. New National Air-Kerma Standard for Low-Energy Electronic Brachytherapy Sources

    PubMed Central

    Seltzer, Stephen M; O’Brien, Michelle; Mitch, Michael G

    2014-01-01

    The new primary standard for low-energy electronic brachytherapy sources for the United States is described. These miniature x-ray tubes are inserted in catheters for interstitial radiation therapy and operate at tube potentials of up to about 50 kV. The standard is based on the realization of the air kerma produced by the x-ray beam at a reference distance in air of 50 cm. PMID:26601044

  19. Estimation of the peak entrance surface air kerma for patients undergoing computed tomography-guided procedures.

    PubMed

    Avilés Lucas, P; Dance, D R; Castellano, I A; Vañó, E

    2005-01-01

    The purpose of this work was to develop a method for estimating the patient peak entrance surface air kerma from measurements using a pencil ionisation chamber on dosimetry phantoms exposed in a computed tomography (CT) scanner. The method described is especially relevant for CT fluoroscopy and CT perfusion procedures where the peak entrance surface air kerma is the risk-related quantity of primary concern. Pencil ionisation chamber measurements include scattered radiation, which is outside the primary radiation field, and that must be subtracted in order to derive the peak entrance surface air kerma. A Monte Carlo computer model has therefore been used to calculate correction factors, which may be applied to measurements of the CT dose index obtained using a pencil ionisation chamber in order to estimate the peak entrance surface air kerma. The calculations were made for beam widths of 5, 7, 10 and 20 mm, for seven positions of the phantom, and for the geometry of a GE HiSpeed CT/i scanner. The program was validated by comparing measurements and calculations of CTDI for various vertical positions of the phantom and by directly estimating the peak ESAK using the program. Both validations showed agreement within statistical uncertainties (standard deviation of 2.3% or less). For the GE machine, the correction factors vary by approximately 10% with slice width for a fixed phantom position, being largest for the 20 mm beam width, and at that beam width range from 0.87 when the phantom surface is at the isocentre to 1.23 when it is displaced vertically by 24 cm.

  20. Air kerma strength characterization of a GZP6 Cobalt-60 brachytherapy source

    PubMed Central

    Toossi, Mohammad Taghi Bahreyni; Ghorbani, Mahdi; Mowlavi, Ali Asghar; Taheri, Mojtaba; Layegh, Mohsen; Makhdoumi, Yasha; Meigooni, Ali Soleimani

    2010-01-01

    Background Task group number 40 (TG-40) of the American Association of Physicists in Medicine (AAPM) has recommended calibration of any brachytherapy source before its clinical use. GZP6 afterloading brachytherapy unit is a 60Co high dose rate (HDR) system recently being used in some of the Iranian radiotherapy centers. Aim In this study air kerma strength (AKS) of 60Co source number three of this unit was estimated by Monte Carlo simulation and in air measurements. Materials and methods Simulation was performed by employing the MCNP-4C Monte Carlo code. Self-absorption of the source core and its capsule were taken into account when calculating air kerma strength. In-air measurements were performed according to the multiple distance method; where a specially designed jig and a 0.6 cm3 Farmer type ionization chamber were used for the measurements. Monte Carlo simulation, in air measurement and GZP6 treatment planning results were compared for primary air kerma strength (as for November 8th 2005). Results Monte Carlo calculated and in air measured air kerma strength were respectively equal to 17240.01 μGym2 h−1 and 16991.83 μGym2 h−1. The value provided by the GZP6 treatment planning system (TPS) was “15355 μGym2 h−1”. Conclusion The calculated and measured AKS values are in good agreement. Calculated-TPS and measured-TPS AKS values are also in agreement within the uncertainties related to our calculation, measurements and those certified by the GZP6 manufacturer. Considering the uncertainties, the TPS value for AKS is validated by our calculations and measurements, however, it is incorporated with a large uncertainty. PMID:24376948

  1. New National Air-Kerma-Strength Standards for 125I and 103Pd Brachytherapy Seeds

    PubMed Central

    Seltzer, Stephen M.; Lamperti, Paul J.; Loevinger, Robert; Mitch, Michael G.; Weaver, James T.; Coursey, Bert M.

    2003-01-01

    The new U.S. measurement standard for the air-kerma strength from low-energy photon-emitting brachytherapy seed sources is formally described in detail. This instrument-based standard was implemented on 1 January 1999, with its salient features and the implications of differences with the previous standard given only through a series of informal communications. The Wide-Angle Free-Air Chamber (WAFAC) is specially designed to realize air kerma from a single-seed source emitting photons with energies up to about 40 keV, and is now used to measure the wide variety of seeds used in prostate-cancer therapy that has appeared in the last few years. For the two 125I seed models that have been subject to both the old and new standards, the new standard reduces the air-kerma strength by 10.3 %. This change is mainly due to the removal of the influence on the measurement of the Ti K x rays produced in the source encapsulation, a component with no clinical significance. PMID:27413614

  2. Determination of the reference air kerma rate for 192Ir brachytherapy sources and the related uncertainty.

    PubMed

    van Dijk, Eduard; Kolkman-Deurloo, Inger-Karine K; Damen, Patricia M G

    2004-10-01

    Different methods exist to determine the air kerma calibration factor of an ionization chamber for the spectrum of a 192Ir high-dose-rate (HDR) or pulsed-dose-rate (PDR) source. An analysis of two methods to obtain such a calibration factor was performed: (i) the method recommended by [Goetsch et al., Med. Phys. 18, 462-467 (1991)] and (ii) the method employed by the Dutch national standards institute NMi [Petersen et al., Report S-EI-94.01 (NMi, Delft, The Netherlands, 1994)]. This analysis showed a systematic difference on the order of 1% in the determination of the strength of 192Ir HDR and PDR sources depending on the method used for determining the air kerma calibration factor. The definitive significance of the difference between these methods can only be addressed after performing an accurate analysis of the associated uncertainties. For an NE 2561 (or equivalent) ionization chamber and an in-air jig, a typical uncertainty budget of 0.94% was found with the NMi method. The largest contribution in the type-B uncertainty is the uncertainty in the air kerma calibration factor for isotope i, N(i)k, as determined by the primary or secondary standards laboratories. This uncertainty is dominated by the uncertainties in the physical constants for the average mass-energy absorption coefficient ratio and the stopping power ratios. This means that it is not foreseeable that the standards laboratories can decrease the uncertainty in the air kerma calibration factors for ionization chambers in the short term. When the results of the determination of the 192Ir reference air kerma rates in, e.g., different institutes are compared, the uncertainties in the physical constants are the same. To compare the applied techniques, the ratio of the results can be judged by leaving out the uncertainties due to these physical constants. In that case an uncertainty budget of 0.40% (coverage factor=2) should be taken into account. Due to the differences in approach between the method

  3. Comparison of air-kerma strength determinations for HDR (192)Ir sources.

    PubMed

    Rasmussen, Brian E; Davis, Stephen D; Schmidt, Cal R; Micka, John A; Dewerd, Larry A

    2011-12-01

    To perform a comparison of the interim air-kerma strength standard for high dose rate (HDR) (192)Ir brachytherapy sources maintained by the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) with measurements of the various source models using modified techniques from the literature. The current interim standard was established by Goetsch et al. in 1991 and has remained unchanged to date. The improved, laser-aligned seven-distance apparatus of the University of Wisconsin Medical Radiation Research Center (UWMRRC) was used to perform air-kerma strength measurements of five different HDR (192)Ir source models. The results of these measurements were compared with those from well chambers traceable to the original standard. Alternative methodologies for interpolating the (192)Ir air-kerma calibration coefficient from the NIST air-kerma standards at (137)Cs and 250 kVp x rays (M250) were investigated and intercompared. As part of the interpolation method comparison, the Monte Carlo code EGSnrc was used to calculate updated values of A(wall) for the Exradin A3 chamber used for air-kerma strength measurements. The effects of air attenuation and scatter, room scatter, as well as the solution method were investigated in detail. The average measurements when using the inverse N(K) interpolation method for the Classic Nucletron, Nucletron microSelectron, VariSource VS2000, GammaMed Plus, and Flexisource were found to be 0.47%, -0.10%, -1.13%, -0.20%, and 0.89% different than the existing standard, respectively. A further investigation of the differences observed between the sources was performed using MCNP5 Monte Carlo simulations of each source model inside a full model of an HDR 1000 Plus well chamber. Although the differences between the source models were found to be statistically significant, the equally weighted average difference between the seven-distance measurements and the well chambers was 0.01%, confirming that it is not necessary to

  4. SU-D-209-01: Can Fluoroscopic Air-Kerma Rates Be Reliably Measured with Solid-State Meters?

    SciTech Connect

    Feng, C; Thai, L; Wagner, L

    Purpose: Ionization chambers remain the standard for calibration of air-kerma rate measuring devices. Despite their strong energy-dependent response, solid state radiation detectors are increasingly used, primarily due to their efficiency in making standardized measurements. To test the reliability of these devices in measuring air-kerma rates, we compared ion chambers measurements with solid-state measurements for various mobile fluoroscopes operated at different beam qualities and air-kerma rates. Methods: Six mobile fluoroscopes (GE OEC models 9800 and 9900) were used to generate test beams. Using various field sizes and dose rate controls, copper attenuators and a lead attenuator were placed at the imagemore » receptor in varying combinations to generate a range of air-kerma rates. Air-kerma rates at 30 centimeters from the image receptors were measured using two 6-cm{sup 3} ion chambers with electrometers (Radcal, models 1015 and 9015) and two with solid state detectors (Unfors Xi and Raysafe X2). No error messages occurred during measurements. However, about two months later, one solid-state device stopped working and was replaced by the manufacturer. Two out of six mobile fluoroscopic units were retested with the replacement unit. Results: Generally, solid state and ionization chambers agreed favorably well, with two exceptions. Before replacement of the detector, the Xi meter when set in the “RF High” mode deviated from ion chamber readings by factors of 2 and 10 with no message indicating error in measurement. When set in the “RF Low” mode, readings were within −4% to +3%. The replacement Xi detector displayed messages alerting the user when settings were not compatible with air-kerma rates. Conclusion: Air-kerma rates can be measured favorably well using solid-state devices, but users must be aware of the possibility that readings can be grossly in error with no discernible indication for the deviation.« less

  5. Plastic Jellyfish.

    ERIC Educational Resources Information Center

    Moseley, Christine

    2000-01-01

    Presents an environmental science activity designed to enhance students' awareness of the hazards of plastic waste for wildlife in aquatic environments. Discusses how students can take steps to reduce the effects of plastic waste. (WRM)

  6. Reference natural radionuclide concentrations in Australian soils and derived terrestrial air kerma rate.

    PubMed

    Kleinschmidt, R

    2017-06-01

    Sediment from drainage catchment outlets has been shown to be a useful means of sampling large land masses for soil composition. Naturally occurring radioactive material concentrations (uranium, thorium and potassium-40) in soil have been collated and converted to activity concentrations using data collected from the National Geochemistry Survey of Australia. Average terrestrial air kerma rate data are derived using the elemental concentration data, and is tabulated for Australia and states for use as baseline reference information. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  7. Air-kerma strength determination of a miniature x-ray source for brachytherapy applications

    NASA Astrophysics Data System (ADS)

    Davis, Stephen D.

    A miniature x-ray source has been developed by Xoft Inc. for high dose-rate brachytherapy treatments. The source is contained in a 5.4 mm diameter water-cooling catheter. The source voltage can be adjusted from 40 kV to 50 kV and the beam current is adjustable up to 300 muA. Electrons are accelerated toward a tungsten-coated anode to produce a lightly-filtered bremsstrahlung photon spectrum. The sources were initially used for early-stage breast cancer treatment using a balloon applicator. More recently, Xoft Inc. has developed vaginal and surface applicators. The miniature x-ray sources have been characterized using a modification of the American Association of Physicists in Medicine Task Group No. 43 formalism normally used for radioactive brachytherapy sources. Primary measurements of air kerma were performed using free-air ionization chambers at the University of Wisconsin (UW) and the National Institute of Standards and Technology (NIST). The measurements at UW were used to calibrate a well-type ionization chamber for clinical verification of source strength. Accurate knowledge of the emitted photon spectrum was necessary to calculate the corrections required to determine air-kerma strength, defined in vacuo. Theoretical predictions of the photon spectrum were calculated using three separate Monte Carlo codes: MCNP5, EGSnrc, and PENELOPE. Each code used different implementations of the underlying radiological physics. Benchmark studies were performed to investigate these differences in detail. The most important variation among the codes was found to be the calculation of fluorescence photon production following electron-induced vacancies in the L shell of tungsten atoms. The low-energy tungsten L-shell fluorescence photons have little clinical significance at the treatment distance, but could have a large impact on air-kerma measurements. Calculated photon spectra were compared to spectra measured with high-purity germanium spectroscopy systems at both UW and

  8. Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities.

    PubMed

    Pujades, M C; Granero, D; Vijande, J; Ballester, F; Perez-Calatayud, J; Papagiannis, P; Siebert, F A

    2014-12-01

    In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for (192)Ir and (60)Co HDR applications to account for several different bunker layouts.For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by (192)Ir and (60)Co will reduce the lead thickness by a factor of five for (192)Ir and ten for (60)Co. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers.The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness.

  9. SU-E-I-27: Estimating KERMA Area Product for CT Localizer Images

    SciTech Connect

    Ogden, K; Greene-Donnelly, K; Bennett, R

    2015-06-15

    Purpose: To estimate the free-in-air KERMA-Area Product (KAP) incident on patients due to CT localizer scans for common CT exams. Methods: In-plane beam intensity profiles were measured in localizer acquisition mode using OSLs for a 64 slice MDCT scanner (Lightspeed VCT, GE Medical Systems, Waukesha WI). The z-axis beam width was measured as a function of distance from isocenter. The beam profile and width were used to calculate a weighted average air KERMA per unit mAs as a function of intercepted x-axis beam width for objects symmetric about the localizer centerline.Patient areas were measured using manually drawn regions and dividedmore » by localizer length to determine average width. Data were collected for 50 head exams (lateral localizer only), 15 head/neck exams, 50 chest exams, and 50 abdomen/pelvis exams. Mean patient widths and acquisition techniques were used to calculate the weighted average free-in-air KERMA, which was multiplied by the patient area to estimate KAP. Results: Scan technique was 120 kV tube voltage, 10 mA current, and table speed of 10 cm/s. The mean ± standard deviation values of KAP were 120 ± 11.6, 469 ± 62.6, 518 ± 45, and 763 ± 93 mGycm{sup 2} for head, head/neck, chest, and abdomen/pelvis exams, respectively. For studies with AP and lateral localizers, the AP/lateral area ratio was 1.20, 1.33, and 1.24 for the head/neck, chest, and abdomen/pelvis exams, respectively. However, the AP/lateral KAP ratios were 1.12, 1.08, and 1.07, respectively. Conclusion: Calculation of KAP in CT localizers is complicated by the non-uniform intensity profile and z-axis beam width. KAP values are similar to those for simple radiographic exams such as a chest radiograph and represent a small fraction of the x-ray exposure at CT. However, as CT doses are reduced the localizer contribution will be a more significant fraction of the total exposure.« less

  10. Plastics Technology.

    ERIC Educational Resources Information Center

    Barker, Tommy G.

    This curriculum guide is designed to assist junior high schools industrial arts teachers in planning new courses and revising existing courses in plastics technology. Addressed in the individual units of the guide are the following topics: introduction to production technology; history and development of plastics; safety; youth leadership,…

  11. ETV Report: Siemens Model V-40R-A150 Open Channel UV System

    EPA Science Inventory

    Verification testing of the Siemens Barrier Sunlight V-40R-A150 UV System was completed at the UV Validation and Research Center of New York (UV Center), located in Johnstown, NY. The V-40R System supplied by Siemens utilizes 40 high-output, low-pressure amalgam lamps, oriented ...

  12. [Measurement of the air kerma using dosimeters embedded in an acrylic phantom in interventional radiology.].

    PubMed

    Kawabe, Atsushi; Shibuya, Koichi; Takeda, Yoshihiro

    2006-01-01

    Interventional radiology procedure guidelines and a measurement manual (IVR guidelines) have been published for the maintenance of interventional equipment with an objective of avoiding serious radiation-induced skin injuries. In the IVR guidelines, the positioning of a dosimeter at the interventional reference point is determined, whereas placement of a phantom is not specified. Therefore, the phantom is placed at any convenient location between the dosimeter and image intensifier. The space around the dosimeter reduces detection of scattered radiation. In this study, dosimeters (consisting of a parallel plate ionization chamber, glass dosimeter and OSL dosimeter) were embedded in the phantom surface to detected scattered radiation accurately. As a result, when dosimeters were embedded in the phantom surface, the air kerma was increased compared with that when dosimeters were placed on the phantom. This suggested that embedded dosimeters were able to detect scattered radiation from the phantom.

  13. Primary Beam Air Kerma Dependence on Distance from Cargo and People Scanners.

    PubMed

    Strom, Daniel J; Cerra, Frank

    2016-06-01

    The distance dependence of air kerma or dose rate of the primary radiation beam is not obvious for security scanners of cargo and people in which there is relative motion between a collimated source and the person or object being imaged. To study this problem, one fixed line source and three moving-source scan-geometry cases are considered, each characterized by radiation emanating perpendicular to an axis. The cases are 1) a stationary line source of radioactive material, e.g., contaminated solution in a pipe; 2) a moving, uncollimated point source of radiation that is shuttered or off when it is stationary; 3) a moving, collimated point source of radiation that is shuttered or off when it is stationary; and 4) a translating, narrow "pencil" beam emanating in a flying-spot, raster pattern. Each case is considered for short and long distances compared to the line source length or path traversed by a moving source. The short distance model pertains mostly to dose to objects being scanned and personnel associated with the screening operation. The long distance model pertains mostly to potential dose to bystanders. For radionuclide sources, the number of nuclear transitions that occur a) per unit length of a line source or b) during the traversal of a point source is a unifying concept. The "universal source strength" of air kerma rate at 1 m from the source can be used to describe x-ray machine or radionuclide sources. For many cargo and people scanners with highly collimated fan or pencil beams, dose varies as the inverse of the distance from the source in the near field and with the inverse square of the distance beyond a critical radius. Ignoring the inverse square dependence and using inverse distance dependence is conservative in the sense of tending to overestimate dose.

  14. Primary Beam Air Kerma Dependence on Distance from Cargo and People Scanners

    SciTech Connect

    Strom, Daniel J.; Cerra, Frank

    The distance dependence of air kerma or dose rate of the primary radiation beam is not obvious for security scanners of cargo and people in which there is relative motion between a collimated source and the person or object being imaged. To study this problem, one fixed line source and three moving-source scan-geometry cases are considered, each characterized by radiation emanating perpendicular to an axis. The cases are 1) a stationary line source of radioactive material, e.g., contaminated solution in a pipe; 2) a moving, uncollimated point source of radiation that is shuttered or off when it is stationary; 3)more » a moving, collimated point source of radiation that is shuttered or off when it is stationary; and 4) a translating, narrow “pencil” beam emanating in a flying-spot, raster pattern. Each case is considered for short and long distances compared to the line source length or path traversed by a moving source. The short distance model pertains mostly to dose to objects being scanned and personnel associated with the screening operation. The long distance model pertains mostly to potential dose to bystanders. For radionuclide sources, the number of nuclear transitions that occur a) per unit length of a line source, or b) during the traversal of a point source, is a unifying concept. The “universal source strength” of air kerma rate at a meter from the source can be used to describe x-ray machine or radionuclide sources. For many cargo and people scanners with highly collimated fan or pencil beams, dose varies as the inverse of the distance from the source in the near field and with the inverse square of the distance beyond a critical radius. Ignoring the inverse square dependence and using inverse distance dependence is conservative in the sense of tending to overestimate dose.« less

  15. Plastic welder

    NASA Technical Reports Server (NTRS)

    Buckley, J. D.; Fox, R. L.; Swain, R. J.

    1980-01-01

    Low-cost, self-contained, portable welder joins plastic parts by induction heating. Welder is useable in any atmosphere or in vacuum and with most types of thermoplastic; plastic components can be joined in situ. Device is applicable to aerospace industry and in automobile, furniture, and construction industries. Power requirements are easily met by battery or solar energy. In welder, toroidal inductor transfers magnetic flux through thermoplastic to screen. Heated screen causes plastic surface on either side to melt and flow into it to form joint.

  16. EPDM plasticizers

    SciTech Connect

    Godail, M.J.

    1983-08-01

    The properties of paraffinic, naphthenic, and aromatic extender oils used as EPDM plasticizers are discussed in detail. Particular attention is given to viscosity, volatility, specific gravity, and aromatic content.

  17. MO-D-213-07: RadShield: Semi- Automated Calculation of Air Kerma Rate and Barrier Thickness

    SciTech Connect

    DeLorenzo, M; Wu, D; Rutel, I

    2015-06-15

    Purpose: To develop the first Java-based semi-automated calculation program intended to aid professional radiation shielding design. Air-kerma rate and barrier thickness calculations are performed by implementing NCRP Report 147 formalism into a Graphical User Interface (GUI). The ultimate aim of this newly created software package is to reduce errors and improve radiographic and fluoroscopic room designs over manual approaches. Methods: Floor plans are first imported as images into the RadShield software program. These plans serve as templates for drawing barriers, occupied regions and x-ray tube locations. We have implemented sub-GUIs that allow the specification in regions and equipment for occupancymore » factors, design goals, number of patients, primary beam directions, source-to-patient distances and workload distributions. Once the user enters the above parameters, the program automatically calculates air-kerma rate at sampled points beyond all barriers. For each sample point, a corresponding minimum barrier thickness is calculated to meet the design goal. RadShield allows control over preshielding, sample point location and material types. Results: A functional GUI package was developed and tested. Examination of sample walls and source distributions yields a maximum percent difference of less than 0.1% between hand-calculated air-kerma rates and RadShield. Conclusion: The initial results demonstrated that RadShield calculates air-kerma rates and required barrier thicknesses with reliable accuracy and can be used to make radiation shielding design more efficient and accurate. This newly developed approach differs from conventional calculation methods in that it finds air-kerma rates and thickness requirements for many points outside the barriers, stores the information and selects the largest value needed to comply with NCRP Report 147 design goals. Floor plans, parameters, designs and reports can be saved and accessed later for modification and

  18. Direct measurement of air kerma rate in air from CDCS J-type caesium-137 therapy sources using a Farmer ionization chamber.

    PubMed

    Poynter, A J

    2000-04-01

    A simple method for directly measuring the reference air kerma rate from J-type 137Cs sources using a Farmer 2571 chamber has been evaluated. The method is useful as an independent means of verifying manufacturers' test data.

  19. SU-E-I-49: Influence of Scanner Output Measurement Technique on KERMA Ratios in CT.

    PubMed

    Ogden, K; Roskopf, M; Scalzetti, E

    2012-06-01

    KERMA ratios (RK) are defined as the ratio of KERMA measured at a specific phantom location (K) to in-air isocenter CT scanner output (KCT). In this work we investigate the impact of measurement methodology on KCT values. OSL dosimeter chips were used to measure KCT for a GE VCT scanner (GE Medical Systems, Waukesha WI), using the 40 mm nominal beam width. Methods included a single point measurement at the center of the beam (1 tube rotation), and extended z-axis measurements using multiple adjacent OSL's (7.5 cm extent), with single tube rotation, multiple contiguous axial scans, and helical scans (pitch of 1.375). Measurements were made in air and on the scan table at 80 and 120 kV. Averaged single point measurements were consistent, with a mean coefficient of variation of 2.5%. For extended measurements with a single tube rotation, the mean value was equivalent to the single point measurements. For multiple contiguous axial scans, the in-air KCT values were higher than the single rotation mean value and single point measurements by 13% and 10.3% at 120 and 80 kV, respectively, and for the on-table measurements the values were 14.9% and 8.1% higher at 120 and 80 kV, respectively. The increase is due to beam overlap caused by z- axis over-beaming. Extended measurements using helical scanning were equivalent to the multiple rotation axial measurements when corrected for the helical pitch. For all methodologies, the in-air values exceeded the on- table measurements by an average of 23% and 19.4% at 80 and 120 kV, respectively. Scanner KCT values must be measured to allow organ dose estimation using published RK values. It is imperative that the KCT measurement methodology is the same as for the published values, or large errors may be introduced into the resulting organ dose estimates. © 2012 American Association of Physicists in Medicine.

  20. Well-ionization chamber response relative to NIST air-kerma strength standard for prostate brachytherapy seeds.

    PubMed

    Mitch, M G; Zimmerman, B E; Lamperti, P J; Seltzer, S M; Coursey, B M

    2000-10-01

    The response of well-ionization chambers to the emissions of 103Pd and 125I radioactive seed sources used in prostate cancer brachytherapy has been measured. Calibration factors relating chamber response (current or dial setting) to measured air-kerma strength have been determined for seeds from nine manufacturers, each with different designs. Variations in well-ionization chamber response relative to measured air-kerma strength have been observed because of differences in the emitted energy spectrum due to both the radionuclide support material (125I seeds) and the mass ratio of 103Pd to 102Pd (103Pd seeds). Obtaining accurate results from quality assurance measurements using well-ionization chambers at a therapy clinic requires knowledge of such differences in chamber response as a function of seed design.

  1. Review of reconstruction of radiation incident air kerma by measurement of absorbed dose in tooth enamel with EPR.

    PubMed

    Wieser, A

    2012-03-01

    Electron paramagnetic resonance dosimetry with tooth enamel has been proved to be a reliable method to determine retrospectively exposures from photon fields with minimal detectable doses of 100 mGy or lower, which is lower than achievable with cytogenetic dose reconstruction methods. For risk assessment or validating dosimetry systems for specific radiation incidents, the relevant dose from the incident has to be calculated from the total absorbed dose in enamel by subtracting additional dose contributions from the radionuclide content in teeth, natural external background radiation and medical exposures. For calculating organ doses or evaluating dosimetry systems the absorbed dose in enamel from a radiation incident has to be converted to air kerma using dose conversion factors depending on the photon energy spectrum and geometry of the exposure scenario. This paper outlines the approach to assess individual dose contributions to absorbed dose in enamel and calculate individual air kerma of a radiation incident from the absorbed dose in tooth enamel.

  2. Comparison of incident air kerma (ki) of common digital and analog radiology procedures in Kohgiluyeh and Boyer-Ahmad province

    NASA Astrophysics Data System (ADS)

    Vafapour, Hassan; Salehi, Zaker

    2018-03-01

    Introduction: Although in many developed countries, Analog radiography (AR) is replaced with digital radiography (DR) but AR is still widely used in many countries included Iran. Therefore, dosimetrically assessment of delivered dose is very important to avoid unnecessary patient dose. Materials and Methods: In this study, all imaging centers in Kohgiluyeh and Boyer-Ahmad were selected. The initial information included the mean kVp and mAs used by the personnel to perform each radiological procedure were gathered through a questionnaire. Barracuda dosimeter was then used to measure Incident air kerma (ki). Data obtained from digital radiography (DR) and analogue radiography (AR) were then analyzed and compared to each other. Results: The mean incident air kerma (ki) for five radiological procedures (chest AP&Lat, Skull AP&Lat, Lumbar spine AP&Lat, Thoracic spine AP&Lat and Pelvis) in digital devices were 0.38&1.34, 2.1&1.94, 4.99&7.83, 4.18& 6.41 and 4.33 mGy and those for analogue devices were 0.7&1.28, 3.05&3.02, 7.25&9.9, 7.125&8.36 and 5.36 mGy, respectively. Discussion and Conclusion: The use of low kVp or high mAs is one of the reasons to increase the incident air kerma (ki) in analogue methods comparing to digital methods in all procedures except the chest (in Lateral view). Also the results, surprisingly, showed that in some of the analogue methods incident air kerma (ki) was less than digital methods which is most probably because of the auto-exposure conditions.

  3. Plastic condoms.

    PubMed

    1968-01-01

    Only simple equipment, simple technology and low initial capital investment are needed in their manufacture. The condoms can be made by people who were previously unskilled or only semi-skilled workers. Plastic condoms differ from those made of latex rubber in that the nature of the plastic film allows unlimited shelf-life. Also, the plastic has a higher degree of lubricity than latex rubber; if there is a demand for extra lubrication in a particular market, this can be provided. Because the plastic is inert, these condoms need not be packaged in hermetically sealed containers. All these attributes make it possible to put these condoms on the distributors' shelves in developing countries competitively with rubber condoms. The shape of the plastic condom is based on that of the lamb caecum, which has long been used as luxury-type condom. The plastic condom is made from plastic film (ethylene ethyl acrilate) of 0.001 inch (0.0254 mm.) thickness. In addition, a rubber ring is provided and sealed into the base of the condom for retention during coitus. The advantage of the plastic condom design and the equipment on which it is made is that production can be carried out either in labour-intensive economy or with varying degrees of mechanization and automation. The uniform, finished condom if made using previously untrained workers. Training of workers can be done in a matter of hours on the two machines which are needed to produce and test the condoms. The plastic film is provided on a double wound roll, and condom blanks are prepared by means of a heat-sealing die on the stamping machine. The rubber rings are united to the condom blanks on an assembly machine, which consists of a mandrel and heat-sealing equipment to seal the rubber ring to the base of the condom. Built into the assembly machine is a simple air-testing apparatus that can detect the smallest pinhole flaw in a condom. The manufacturing process is completed by unravelling the condom from the assembly

  4. Monte Carlo simulations in CT for the study of the surface air kerma and energy imparted to phantoms of varying size and position

    NASA Astrophysics Data System (ADS)

    Avilés Lucas, P.; Dance, D. R.; Castellano, I. A.; Vañó, E.

    2004-04-01

    A Monte Carlo computational model of CT has been developed and used to investigate the effect of various physical factors on the surface air kerma length product, the peak surface air kerma, the air kerma length product within a phantom and the energy imparted. The factors investigated were the bow-tie filter and the size, shape and position of a phantom which simulates the patient. The calculations show that the surface air kerma length product and the maximum surface air kerma are mainly dependent on phantom position and decrease along the vertical axis of the CT plane as the phantom surface moves away from the isocentre along this axis. As a result, measurements using standard body dosimetry phantoms may underestimate the skin dose for real patients. This result is specially important for CT fluoroscopic procedures: for an adult patient the peak skin dose can be 37% higher than that estimated with a standard measurement on the body AAPM (American Association of Physicists in Medicine) phantom. The results also show that the energy imparted to a phantom is mainly influenced by phantom size and is nearly independent of phantom position (within 3%) and shape (up to 5% variation). However, variations of up to 30% were found for the air kerma to regions within the AAPM body phantom when it is moved vertically. This highlights the importance of calculating doses to organs taking into account their size and position within the gantry.

  5. Direct calibration of a reference standard against the air kerma strength primary standard, at 192Ir HDR energy.

    PubMed

    Rajan, K N Govinda; Selvam, T Palani; Bhatt, B C; Vijayam, M; Patki, V S; Vinatha; Pendse, A M; Kannan, V

    2002-04-07

    The primary standard of low air kerma rate sources or beams, maintained at the Radiological Standards Laboratory (RSL) of the Bhabha Atomic Research Centre (BARC), is a 60 cm3 spherical graphite ionization chamber. A 192Ir HDR source was standardized at the hospital site in units of air kerma strength (AKS) using this primary standard. A 400 cm3 bakelite chamber, functioning as a reference standard at the RSL for a long period, at low air kerma rates (compared to external beam dose rates), was calibrated against the primary standard. It was seen that the primary standard and the reference standard, both being of low Z, showed roughly the same scatter response and yielded the same calibration factor for the 400 cm3 reference chamber, with or without room scatter. However, any likelihood of change in the reference chamber calibration factor would necessitate the re-transport of the primary standard to the hospital site for re-calibration. Frequent transport of the primary standard can affect the long-term stability of the primary standard, due to its movement or other extraneous causes. The calibration of the reference standard against the primary standard at the RSL, for an industrial type 192Ir source maintained at the laboratory, showed excellent agreement with the hospital calibration, making it possible to check the reference chamber calibration at RSL itself. Further calibration procedures have been developed to offer traceable calibration of the hospital well ionization chambers.

  6. NaI(Tl) scintillator detectors stripping procedure for air kerma measurements of diagnostic X-ray beams

    NASA Astrophysics Data System (ADS)

    Oliveira, L. S. R.; Conti, C. C.; Amorim, A. S.; Balthar, M. C. V.

    2013-03-01

    Air kerma is an essential quantity for the calibration of national standards used in diagnostic radiology and the measurement of operating parameters used in radiation protection. Its measurement within the appropriate limits of accuracy, uncertainty and reproducibility is important for the characterization and control of the radiation field for the dosimetry of the patients submitted to diagnostic radiology and, also, for the assessment of the system which produces radiological images. Only the incident beam must be considered for the calculation of the air kerma. Therefore, for energy spectrum, counts apart the total energy deposition in the detector must be subtracted. It is necessary to establish a procedure to sort out the different contributions to the original spectrum and remove the counts representing scattered photons in the detector's materials, partial energy deposition due to the interactions in the detector active volume and, also, the escape peaks contributions. The main goal of this work is to present spectrum stripping procedure, using the MCNP Monte Carlo computer code, for NaI(Tl) scintillation detectors to calculate the air kerma due to an X-ray beam usually used in medical radiology. The comparison between the spectrum before stripping procedure against the reference value showed a discrepancy of more than 63%, while the comparison with the same spectrum after the stripping procedure showed a discrepancy of less than 0.2%.

  7. NOTE: Monte Carlo evaluation of kerma in an HDR brachytherapy bunker

    NASA Astrophysics Data System (ADS)

    Pérez-Calatayud, J.; Granero, D.; Ballester, F.; Casal, E.; Crispin, V.; Puchades, V.; León, A.; Verdú, G.

    2004-12-01

    In recent years, the use of high dose rate (HDR) after-loader machines has greatly increased due to the shift from traditional Cs-137/Ir-192 low dose rate (LDR) to HDR brachytherapy. The method used to calculate the required concrete and, where appropriate, lead shielding in the door is based on analytical methods provided by documents published by the ICRP, the IAEA and the NCRP. The purpose of this study is to perform a more realistic kerma evaluation at the entrance maze door of an HDR bunker using the Monte Carlo code GEANT4. The Monte Carlo results were validated experimentally. The spectrum at the maze entrance door, obtained with Monte Carlo, has an average energy of about 110 keV, maintaining a similar value along the length of the maze. The comparison of results from the aforementioned values with the Monte Carlo ones shows that results obtained using the albedo coefficient from the ICRP document more closely match those given by the Monte Carlo method, although the maximum value given by MC calculations is 30% greater.

  8. Plastics Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document contains 16 units to consider for use in a tech prep competency profile for the occupation of plastics technician. All the units listed will not necessarily apply to every situation or tech prep consortium, nor will all the competencies within each unit be appropriate. Several units appear within each specific occupation and would…

  9. Pervasive plastic

    NASA Astrophysics Data System (ADS)

    2018-05-01

    Human manipulation of hydrocarbons — as fuel and raw materials for modern society — has changed our world and the indelible imprint we will leave in the rock record. Plastics alone have permeated our lives and every corner of our planet.

  10. SU-F-T-33: Air-Kerma Strength and Dose Rate Constant by the Full Monte Carlo Simulations

    SciTech Connect

    Tsuji, S; Oita, M; Narihiro, N

    2016-06-15

    Purpose: In general, the air-kerma strength (Sk) has been determined by the energy weighting the photon energy fluence and the corresponding mass-energy absorption coefficient or mass-energy transfer coefficient. Kerma is an acronym for kinetic energy released per unit mass, defined as the sum of the initial kinetic energies of all the charged particles. Monte Carlo (MC) simulations can investigate the kinetic energy of the charged particles after photo interactions and sum the energy. The Sk of {sup 192}Ir source is obtained in the full MC simulation and finally the dose rate constant Λ is determine. Methods: MC simulations were performedmore » using EGS5 with the microSelectron HDR v2 type of {sup 192}Ir source. The air-kerma rate obtained to sum the electron kinetic energy after photoelectric absorption or Compton scattering for transverse-axis distance from 1 to 120 cm with a 10 m diameter air phantom. Absorbed dose in water is simulated with a 30 cm diameter water phantom. The transport cut-off energy is 10 keV and primary photons from the source need two hundred and forty billion in the air-kerma rate and thirty billion in absorbed dose in water. Results: Sk is multiplied by the square of the distance in air-kerma rate and determined by fitting a linear function. The result of Sk is (2.7039±0.0085)*10-{sup −11} µGy m{sup 2} Bq{sup −1} s{sup −1}. Absorbed dose rate in water at 1 cm transverse-axis distance D(r{sub 0}, θ{sub 0}) is (3.0114±0.0015)*10{sup −11} cGy Bq{sup −1} s{sup −1}. Conclusion: From the results, dose rate constant Λ of the microSelectron HDR v2 type of {sup 192}Ir source is (1.1137±0.0035) cGy h{sup −1} U{sup −1} by the full MC simulations. The consensus value conΛ is (1.109±0.012) cGy h{sup −1} U{sup −1}. The result value is consistent with the consensus data conΛ.« less

  11. GLASS FIBER REINFORCED PLASTICS,

    DTIC Science & Technology

    Contents: Fibrous glass fillers Binders used in the glass plastic industry Method of manufacturing glass plastics and glass plastic articles Properties of fiberglass Primary areas for use of glass fibre reinforced plastics

  12. Shop test of the 501F; A 150 MW combustion turbine

    SciTech Connect

    Entenmann, D.T.; North, W.E.; Fukue, I.

    1991-10-01

    The 501F is a 150 MW-class 60 Hz engine jointly developed by Westinghouse Electric Corporation and Mitsubishi Heavy Industries, Ltd. This paper describes the full-load shop test program for the prototype engine, as carried out in Takasago, Japan. The shop test included a full range of operating conditions, from startup through full load at the 1260{degrees} C (2300{degrees} F) design turbine inlet temperature. The engine was prepared with more than 1500 instrumentation points to monitor flow path characteristics, metal temperatures, displacements, pressures, cooling circuit characteristics, strains, sound pressure levels, and exhaust emissions. The results of this shop test indicate themore » new 501F engine design and development effort to be highly successful. The engine exceeds power and overall efficiency expectations, thus verifying the new concepts and design improvements.« less

  13. A 150 and 300 kW lightweight diesel aircraft engine design study

    NASA Technical Reports Server (NTRS)

    Brouwers, A. P.

    1980-01-01

    The diesel engine was reinvestigated as an aircraft powerplant through design study conducted to arrive at engine configurations and applicable advanced technologies. Two engines are discussed, a 300 kW six-cylinder engine for twin engine general aviation aircraft and a 150 kW four-cylinder engine for single engine aircraft. Descriptions of each engine include concept drawings, a performance analysis, stress and weight data, and a cost study. This information was used to develop two airplane concepts, a six-place twin and a four-place single engine aircraft. The aircraft study consists of installation drawings, computer generated performance data, aircraft operating costs, and drawings of the resulting airplanes. The performance data show a vast improvement over current gasoline-powered aircraft.

  14. Radiation hard pixel sensors using high-resistive wafers in a 150 nm CMOS processing line

    NASA Astrophysics Data System (ADS)

    Pohl, D.-L.; Hemperek, T.; Caicedo, I.; Gonella, L.; Hügging, F.; Janssen, J.; Krüger, H.; Macchiolo, A.; Owtscharenko, N.; Vigani, L.; Wermes, N.

    2017-06-01

    Pixel sensors using 8'' CMOS processing technology have been designed and characterized offering the benefits of industrial sensor fabrication, including large wafers, high throughput and yield, as well as low cost. The pixel sensors are produced using a 150 nm CMOS technology offered by LFoundry in Avezzano. The technology provides multiple metal and polysilicon layers, as well as metal-insulator-metal capacitors that can be employed for AC-coupling and redistribution layers. Several prototypes were fabricated and are characterized with minimum ionizing particles before and after irradiation to fluences up to 1.1 × 1015 neq cm-2. The CMOS-fabricated sensors perform equally well as standard pixel sensors in terms of noise and hit detection efficiency. AC-coupled sensors even reach 100% hit efficiency in a 3.2 GeV electron beam before irradiation.

  15. Reference air kerma rate calibration system for high dose rate Ir-192 brachytherapy sources in Taiwan

    NASA Astrophysics Data System (ADS)

    Chu, Wei-Han; Yuan, Ming-Chen; Lee, Jeng-Hung; Lin, Yi-Chun

    2017-11-01

    Ir-192 sources are widely used in brachytherapy and the number of treatments is around seven thousand for the use of the high dose rate (HDR) Ir-192 brachytherapy source per year in Taiwan. Due to its physical half-life of 73.8 days, the source should be replaced four times per year to maintain the HDR treatment mode (DDEP, 2005; Coursey et al., 1992). When doing this work, it must perform the source dose trace to assure the dose accuracy. To establish the primary measurement standard of reference air kerma rate(RAKR) for the HDR Ir-192 brachytherapy sources in Taiwan, the Institute of Nuclear Energy Research (INER) fabricated a dual spherical graphite-walled cavity ionization chambers system to directly measure the RAKR of the Ir-192 brachytherapy source. In this system, the ion-charge was accumulated by the two ionization chambers and after correction for the ion recombination, temperature, atmosphere pressure, room scattering, graphite-wall attenuation, air attenuation, source decay, stem effect, and so on. The RAKR of the Ir-192 source was obtained in the ambient conditions of 22 °C and one atmosphere. The measurement uncertainty of the system was around 0.92% in 96% confidence level (k=2.0). To verify the accuracy of the result, the source calibration comparison has been made at the National Radiation Standard Laboratory (NRSL) of INER and Physikalisch-Technische Bundesanstalt (PTB, Germany) in 2015. The ratio of the measurement results between INER and PTB, INER/PTB, was 0.998±0.027 (k=2) which showed good consistency and the performance of the system was verified.

  16. Calibration methodology application of kerma area product meters in situ: Preliminary results

    NASA Astrophysics Data System (ADS)

    Costa, N. A.; Potiens, M. P. A.

    2014-11-01

    The kerma-area product (KAP) is a useful quantity to establish the reference levels of conventional X-ray examinations. It can be obtained by measurements carried out with a KAP meter on a plane parallel transmission ionization chamber mounted on the X-ray system. A KAP meter can be calibrated in laboratory or in situ, where it is used. It is important to use one reference KAP meter in order to obtain reliable quantity of doses on the patient. The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. It was manufactured following the IEC 60580 recommendations, an international standard for KAP meters. This study had the aim to calibrate KAP meters using the PDC in situ. Previous studies and the quality control program of the PDC have shown that it has good function in characterization tests of dosimeters with ionization chamber and it also has low energy dependence. Three types of KAP meters were calibrated in four different diagnostic X-ray equipments. The voltages used in the two first calibrations were 50 kV, 70 kV, 100 kV and 120 kV. The other two used 50 kV, 70 kV and 90 kV. This was related to the equipments limitations. The field sizes used for the calibration were 10 cm, 20 cm and 30 cm. The calibrations were done in three different cities with the purpose to analyze the reproducibility of the PDC. The results gave the calibration coefficient for each KAP meter and showed that the PDC can be used as a reference instrument to calibrate clinical KAP meters.

  17. Comparison for Air Kerma from Radiation Protection Gamma-ray Beams with Brazilian Network - 2016/2017

    NASA Astrophysics Data System (ADS)

    Cabral, TS; da Silva, CNM; Potiens, MPA; Soares, CMA; Silveira, RR; Khoury, H.; Saito, V.; Fernandes, E.; Cardoso, WF; de Oliveira, HPS; Pires, MA; de Amorim, AS; Balthar, M.

    2018-03-01

    The results of the comparison involving 9 laboratories in Brazil are reported. The measured quantity was the air kerma in 137Cs and 60Co, at the level of radioprotection. The comparison was conducted by the National Laboratory Metrology of Ionizing Radiation (LNMRI/IRD) from October 2016 to March 2017. The largest deviation between the calibration coefficients was 0.8% for 137Cs and 0.7% for 60Co. This proficiency exercise proved the technical capacity of the Brazilian calibration network in radiation monitors and the results were used by some in the implementation of the standard ISO/IEC 17025.

  18. Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.

    PubMed

    Behrens, R

    2012-09-01

    The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037.

  19. APMP key comparison for the measurement of air kerma for 60Co (APMP.RI(I)-K1.1)

    NASA Astrophysics Data System (ADS)

    Webb, D. V.; Lee, J.-H.; Budiantari, C. T.; Laban, J.; Saito, N.; Srimanoroth, S.; Khaled, N. E.

    2016-01-01

    The results are reported for an APMP.R(I)-K1.1 comparison that extends the regional comparison of standards for air kerma APMP.R(I)-K1 to several laboratories unable to participate earlier. The comparison was conducted with the goal of supporting the relevant calibration and measurement capabilities (CMCs) planned for publication by the participant laboratories. The comparison was conducted by the pilot laboratory, the Australian Radiation Protection and Nuclear Safety (ARPANSA), Australia, supported by the Institute of Nuclear Energy Research (INER), Taiwan, in a modified ring-shaped arrangement from September 2009 to November 2010, in parallel with an APMP.R(I)-K4 comparison being piloted by the INER. The laboratories that took part in the comparison were the ARPANSA, the Centre of Technology of Radiation Safety and Metrology (PTKMR-BATAN), Indonesia, the Division of Radiation and Medical Devices (DMSC), Thailand, the INER, the National Centre for Radiation Science (NCRS), New Zealand, the National Institute for Standards (NIS), Egypt and the National Metrology Institute of Japan (NMIJ/AIST), Japan. The two primary laboratories, ARPANSA and NMIJ, were chosen as the linking laboratories. Three ionization chambers were used as transfer instruments to be calibrated in terms of air kerma in 60Co radiotherapy beams. The comparison result is based on the ratio between the air kerma calibration coefficients (NK) determined by the participants and the mean of the results of the linking laboratories. The mean comparison ratio was found to be within 0.5 % of the key comparison reference value KCRV. The largest deviation between any two comparison ratios for the three chambers in terms of air kerma was 2.0 %. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE) in terms of the deviations of the results and their associated uncertainties. As a result of this APMP comparison, the BIPM key comparison database (KCDB) should

  20. MO-D-BRD-04: NIST Air-Kerma Standard for Electronic Brachytherapy Calibrations

    SciTech Connect

    Mitch, M.

    Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of

  1. Design and Validation of a 150 MHz HFFQCM Sensor for Bio-Sensing Applications

    PubMed Central

    Fernández, Román; García, Pablo; García, María; Jiménez, Yolanda; Arnau, Antonio

    2017-01-01

    Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor’s fragility, these requirements include a low-volume flow chamber in the nanoliter range, and a system approach that provides the appropriate pressure control for assuring liquid confinement while maintaining the integrity of the sensor with a good base line stability and easy sensor replacement. The sensor characteristics make it suitable for consideration as the elemental part of a sensor matrix in a multichannel platform for point of care applications. PMID:28885551

  2. A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography

    SciTech Connect

    Kharrati, Hedi

    2005-05-01

    In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations andmore » does not exceed 75% for the leakage radiation.« less

  3. Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams.

    PubMed

    Seltzer, Stephen M; Bergstrom, Paul M

    2003-01-01

    Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from (60)Co, (137)Cs, and (192)Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for (60)Co beams, +0.64 % to +1.07 % (depending on the chamber) for (137)Cs beams, and -0.06 % for the single chamber used in the measurement of the standardized (192)Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work.

  4. Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams

    PubMed Central

    Seltzer, Stephen M.; Bergstrom, Paul M.

    2003-01-01

    Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from 60Co, 137Cs, and 192Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for 60Co beams, +0.64 % to +1.07 % (depending on the chamber) for 137Cs beams, and −0.06 % for the single chamber used in the measurement of the standardized 192Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work. PMID:27413615

  5. Comparison of the NIST and PTB Air-Kerma Standards for Low-Energy X-Rays.

    PubMed

    O'Brien, Michelle; Bueermann, Ludwig

    2009-01-01

    A comparison has been made of the air-kerma standards for low-energy x rays at the National Institute of Standards and Technology (NIST) and the Physikalisch-Technische Bundesanstalt (PTB). The comparison involved a series of measurements at the PTB and the NIST using the air-kerma standards and two NIST reference-class transfer ionization chamber standards. Results are presented for the reference radiation beam qualities in the range from 25 kV to 50 kV for low energy x rays, including the techniques used for mammography dose traceability. The tungsten generated reference radiation qualities, between 25 kV and 50 kV used for this comparison, are new to NIST; therefore this comparison will serve as the preliminary comparison for NIST and a verification of the primary standard correction factors. The mammography comparison will repeat two previously unpublished comparisons between PTB and NIST. The results show the standards to be in reasonable agreement within the standard uncertainty of the comparison of about 0.4 %.

  6. Comparison of the NIST and NPL Air Kerma Standards Used for X-Ray Measurements Between 10 kV and 80 kV

    PubMed Central

    O’Brien, M.; Lamperti, P.; Williams, T.; Sander, T.

    2000-01-01

    A direct comparison was made between the air kerma primary standards used for the measurements of low-energy x rays at the National Institute of Standards and Technology (NIST) and the National Physical Laboratory (NPL). The comparison was conducted at the NPL using NPL reference radiation qualities between 10 kV and 80 kV. The results show the primary air-kerma standards to agree within 0.6 % of their values for beam qualities up to 80 kV. PMID:27551632

  7. Absorbed dose to water based dosimetry versus air kerma based dosimetry for high-energy photon beams: an experimental study.

    PubMed

    Palmans, Hugo; Nafaa, Laila; De, Jans Jo; Gillis, Sofie; Hoornaert, Marie-Thérèse; Martens, Chantal; Piessens, Marleen; Thierens, Hubert; Van der Plaetsen, Ann; Vynckier, Stefaan

    2002-02-07

    In recent years, a change has been proposed from air kerma based reference dosimetry to absorbed dose based reference dosimetry for all radiotherapy beams of ionizing radiation. In this paper, a dosimetry study is presented in which absorbed dose based dosimetry using recently developed formalisms was compared with air kerma based dosimetry using older formalisms. Three ionization chambers of each of three different types were calibrated in terms of absorbed dose to water and air kerma and sent to five hospitals. There, reference dosimetry with all the chambers was performed in a total of eight high-energy clinical photon beams. The selected chamber types were the NE2571, the PTW-30004 and the Wellhöfer-FC65G (previously Wellhöfer-IC70). Having a graphite wall, they exhibit a stable volume and the presence of an aluminium electrode ensures the robustness of these chambers. The data were analysed with the most important recommendations for clinical dosimetry: IAEA TRS-398, AAPM TG-51, IAEA TRS-277, NCS report-2 (presently recommended in Belgium) and AAPM TG-21. The necessary conversion factors were taken from those protocols, or calculated using the data in the different protocols if data for a chamber type are lacking. Polarity corrections were within 0.1% for all chambers in all beams. Recombination corrections were consistent with theoretical predictions, did not vary within a chamber type and only slightly between different chamber types. The maximum chamber-to-chamber variations of the dose obtained with the different formalisms within the same chamber type were between 0.2% and 0.6% for the NE2571, between 0.2% and 0.6% for the PTW-30004 and 0.1% and 0.3% for the Wellhöfer-FC65G for the different beams. The absorbed dose results for the NE2571 and Wellhöfer-FC65G chambers were in good agreement for all beams and all formalisms. The PTW-30004 chambers gave a small but systematically higher result compared to the result for the NE2571 chambers (on the

  8. Design assessment of a 150 kWt CFBC Test Unit

    SciTech Connect

    Batu, A.; Selcuk, N.; Kulah, G.

    2010-04-15

    For clean and efficient energy generation from coal, the most suitable technology known to date is 'Fluidized Bed Combustion' technology. Applications of circulating fluidized bed (CFB) combustion technology have been steadily increasing in both capacity and number over the past decade. Designs of these units have been based on the combustion tests carried out in pilot scale facilities to determine the combustion and desulfurization characteristics of coal and limestone reserves in CFB conditions. Similarly, utilization of Turkish lignites in CFB boilers necessitates adaptation of CFB combustion technology to these resources. However, the design of these test units are not basedmore » on firing coals with high ash, volatile matter and sulfur contents like Turkish lignites. For this purpose, a 150 kWt CFB combustor test unit is designed and constructed in Chemical Engineering Department of Middle East Technical University, based on the extensive experience acquired at the existing 0.3 MWt Bubbling Atmospheric Fluidized Bed Combustor (AFBC) Test Rig. Following the commissioning tests, a combustion test is carried out for investigation of combustion characteristics of Can lignite in CFB conditions and for assessment of the design of test unit. Comparison of the design outputs with experimental results reveals that most of the predictions and assumptions have acceptable agreement with the operating conditions. In conclusion, the performance of 150 kWt CFBC Test Unit is found to be satisfactory to be utilized for the long term research studies on combustion and desulfurization characteristics of indigenous lignite reserves in circulating fluidized bed combustors. (author)« less

  9. Toxicological Threats of Plastic

    EPA Pesticide Factsheets

    Plastics pose both physical (e.g., entanglement, gastrointestinal blockage, reef destruction) and chemical threats (e.g., bioaccumulation of the chemical ingredients of plastic or toxic chemicals sorbed to plastics) to wildlife and the marine ecosystem.

  10. Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy.

    PubMed

    Ebenau, Melanie; Radeck, Désirée; Bambynek, Markus; Sommer, Holger; Flühs, Dirk; Spaan, Bernhard; Eichmann, Marion

    2016-08-01

    Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm(3)) made from the commonly used plastic scintillator BC400. Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a (60)Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks' formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks' formula was determined to be kB = (12.3 ± 0.9) mg MeV(-1) cm(-2). The energy response was quantified relative to the response to (60)Co which is the common radiation quality for the calibration of therapy dosemeters. The observed energy dependence could be well explained with the

  11. Air-kerma strength determination of a new directional {sup 103}Pd source

    SciTech Connect

    Aima, Manik, E-mail: aima@wisc.edu; Reed, Joshua L.; DeWerd, Larry A.

    2015-12-15

    Purpose: A new directional {sup 103}Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing {sup 103}Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active {sup 103}Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normallymore » used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S{sub K}) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S{sub K} to a well-type ionization chamber. Methods: S{sub K} measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S{sub K} from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S{sub K} with the presence of gold fluorescent energy lines. In addition to S{sub K} measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S{sub K} values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to

  12. Air-kerma strength determination of a new directional (103)Pd source.

    PubMed

    Aima, Manik; Reed, Joshua L; DeWerd, Larry A; Culberson, Wesley S

    2015-12-01

    A new directional (103)Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing (103)Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active (103)Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S(K)) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S(K) to a well-type ionization chamber. S(K) measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S(K) from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S(K) with the presence of gold fluorescent energy lines. In addition to S(K) measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S(K) values for a directional source within a cylindrically symmetric measurement volume. The UW VAFAC was successfully used to measure the S(K) of four CivaDots with reproducibilities within 0.3%. Monte Carlo

  13. Air-kerma strength determination of a new directional 103Pd source

    PubMed Central

    Reed, Joshua L.; DeWerd, Larry A.; Culberson, Wesley S.

    2015-01-01

    Purpose: A new directional 103Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing 103Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active 103Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber. Methods: SK measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity SK from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the mcnp 6 Monte Carlo code in order to determine SK with the presence of gold fluorescent energy lines. In addition to SK measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating SK values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the SK of four CivaDots with reproducibilities within 0.3%. Monte

  14. A 150-year conundrum: cranial robusticity and its bearing on the origin of aboriginal australians.

    PubMed

    Curnoe, Darren

    2011-01-20

    The origin of Aboriginal Australians has been a central question of palaeoanthropology since its inception during the 19th Century. Moreover, the idea that Australians could trace their ancestry to a non-modern Pleistocene population such as Homo erectus in Southeast Asia have existed for more than 100 years, being explicitly linked to cranial robusticity. It is argued here that in order to resolve this issue a new program of research should be embraced, one aiming to test the full range of alternative explanations for robust morphology. Recent developments in the morphological sciences, especially relating to the ontogeny of the cranium indicate that character atomisation, an approach underpinning phylogenetic reconstruction, is fraught with difficulties. This leads to the conclusion that phylogenetic-based explanations for robusticity should be reconsidered and a more parsimonious approach to explaining Aboriginal Australian origins taken. One that takes proper account of the complex processes involved in the growth of the human cranium rather than just assuming natural selection to explain every subtle variation seen in past populations. In doing so, the null hypothesis that robusticity might result from phenotypic plasticity alone cannot be rejected, a position at odds with both reticulate and deep-time continuity models of Australian origins.

  15. A 150-Year Conundrum: Cranial Robusticity and Its Bearing on the Origin of Aboriginal Australians

    PubMed Central

    Curnoe, Darren

    2011-01-01

    The origin of Aboriginal Australians has been a central question of palaeoanthropology since its inception during the 19th Century. Moreover, the idea that Australians could trace their ancestry to a non-modern Pleistocene population such as Homo erectus in Southeast Asia have existed for more than 100 years, being explicitly linked to cranial robusticity. It is argued here that in order to resolve this issue a new program of research should be embraced, one aiming to test the full range of alternative explanations for robust morphology. Recent developments in the morphological sciences, especially relating to the ontogeny of the cranium indicate that character atomisation, an approach underpinning phylogenetic reconstruction, is fraught with difficulties. This leads to the conclusion that phylogenetic-based explanations for robusticity should be reconsidered and a more parsimonious approach to explaining Aboriginal Australian origins taken. One that takes proper account of the complex processes involved in the growth of the human cranium rather than just assuming natural selection to explain every subtle variation seen in past populations. In doing so, the null hypothesis that robusticity might result from phenotypic plasticity alone cannot be rejected, a position at odds with both reticulate and deep-time continuity models of Australian origins. PMID:21350636

  16. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

    PubMed

    Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

    2014-12-01

    The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, αγ)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Paying and playing with plastic. The meaning of plastics, plasticity, and plastic surgery.

    PubMed

    Williams, D

    1996-11-01

    Plastics are not only the proverbial everyday commodity, but they also permeate almost every aspect of medical devices, from technology to clinical application. This article addresses some of the confusing features of plasticity as they relate to the materials called plastics, to the phenomena of material plasticity, and to the clinical and biological usage of the word.

  18. Providing plastic zone extrusion

    SciTech Connect

    Manchiraju, Venkata Kiran; Feng, Zhili; David, Stan A.

    Plastic zone extrusion may be provided. First, a compressor may generate frictional heat in stock to place the stock in a plastic zone of the stock. Then, a conveyer may receive the stock in its plastic zone from the compressor and transport the stock in its plastic zone from the compressor. Next, a die may receive the stock in its plastic zone from the conveyer and extrude the stock to form a wire.

  19. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the ININ, Mexico and the BIPM in 137Cs gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Alvarez Romero, J. T.; De la Cruz Hernández, D.; Cabrera Vertti, M. R.; Tovar-Muñoz, V. M.

    2015-01-01

    A direct comparison of the standards for air kerma of the Instituto Nacional de Investigaciones Nucleares (ININ), Mexico, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in February 2015. The comparison result, evaluated as a ratio of the ININ and the BIPM standards for air kerma, is 1.0048 with a combined standard uncertainty of 2.0 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Processing of plastics

    PubMed Central

    Spaak, Albert

    1975-01-01

    An overview is given of the processing of plastic materials from the handling of polymers in the pellet and powder form to manufacturing of a plastic fabricated product. Various types of equipment used and melt processing ranges of various polymer formulations to make the myriad of plastic products that are commercially available are discussed. PMID:1175556

  1. Plastics in Building.

    ERIC Educational Resources Information Center

    Skeist, Irving, Ed.

    The evaluation and use of plastics in the construction industry are explained. The contributors offer extensive, timely, and thoroughly researched data on the chemistry, properties, functions, engineering behavior, and specific applications of plastics to building requirements. The major subjects discussed in depth are--(1) the role of plastics in…

  2. Tomorrow's Plastic World

    ERIC Educational Resources Information Center

    Macdonald, Averil

    2005-01-01

    Far from being just cheap packaging materials, plastics may be the materials of tomorrow. Plastic can conduct electricity, and this opens up a host of high-tech possibilities in the home and in energy generation. These possibilities are discussed here along with how plastic can be recycled and perhaps even grown.

  3. Effect of bedside shielding on air-kerma rates around gynecologic intracavitary brachytherapy patients containing sup 226 Ra or sup 137 Cs

    SciTech Connect

    Papin, P.J.; Ramsey, M.J.; LaFontaine, R.L.

    An anthropomorphic phantom was implanted with 226Ra or 137Cs gynecologic intracavitary brachytherapy sources. Air-kerma rate measurements were taken at 10-cm increments along a horizontal plane from the side of the bed at 50 cm, 87 cm, and 136 cm heights above the floor. Five portable lead shields were placed at the head, at the foot and along one side of the bed and readings were taken again at the corresponding heights above, below and behind the shields. The readings were normalized to 100-mg Ra equivalence, and air-kerma rate curves were drawn allowing for the comparison of 226Ra and 137Cs withmore » and without lead shields. The data demonstrated that the air-kerma rates for 137Cs were reduced more than those for 226Ra with the use of the portable lead shields. There was four times the transmission with 226Ra than with 137Cs. The optimal placement was with the lateral bedside shields proximal to the head and foot closest to the bed, with the middle shield overlapping in back. The shields at the head and foot should extend out and overlap the bedside shields. The level of the sources should be positioned near the bottom of the shields. This information will provide the medical health physicist with an estimate of air-kerma rates for both 226Ra and 137Cs with and without shielding for evaluating personnel exposures as well as the effectiveness of current shielding in relation to radiation protection requirements in adjacent rooms or hallways.« less

  4. Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and 137Cs Gamma-Ray Beams

    PubMed Central

    O’Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

    2010-01-01

    Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients. PMID:27134777

  5. Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and (137)Cs Gamma-Ray Beams.

    PubMed

    O'Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

    2010-01-01

    Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients.

  6. Biodegradability of plastics.

    PubMed

    Tokiwa, Yutaka; Calabia, Buenaventurada P; Ugwu, Charles U; Aiba, Seiichi

    2009-08-26

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

  7. Biodegradability of Plastics

    PubMed Central

    Tokiwa, Yutaka; Calabia, Buenaventurada P.; Ugwu, Charles U.; Aiba, Seiichi

    2009-01-01

    Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed. PMID:19865515

  8. KEY COMPARISON: Final report of the SIM 60Co air-kerma comparison SIM.RI(I)-K1

    NASA Astrophysics Data System (ADS)

    Ross, C. K.; Shortt, K. R.; Saravi, M.; Meghzifene, A.; Tovar, V. M.; Barbosa, R. A.; da Silva, C. N.; Carrizales, L.; Seltzer, S. M.

    2008-01-01

    Transfer chambers were used to compare the standards for 60Co air kerma maintained by seven laboratories. Six of the laboratories are members of the Sistema Interamericano de Metrología (SIM) regional metrology organization while the seventh is the International Atomic Energy Agency (IAEA) laboratory in Vienna. The National Research Council (NRC) acted as the pilot laboratory for the comparison. Because of the participation of laboratories holding primary standards, the comparison results could be linked to the key comparison reference value maintained by the Bureau International des Poids et Mesures (BIPM). The results for all laboratories were within the expanded uncertainty (two standard deviations) of the reference value. The estimated relative standard uncertainty of the comparison between any pair of laboratories ranged from 0.5% to 1.0%. The largest discrepancy between any two laboratories was 1.0%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  9. MO-FG-CAMPUS-IeP1-04: Kerma Area Product Calculation for Non-Uniform X-Ray Fields Using a Skin Dose Tracking System

    SciTech Connect

    Vijayan, S; Xiong, Z; Rudin, S

    Purpose: The functionality of the Dose-Tracking System (DTS) has been expanded to include the calculation of the Kerma-Area Product (KAP) for non-uniform x-ray fields such as result from the use of compensation filters during fluoroscopic procedures Methods: The DTS calculates skin dose during fluoroscopic interventions and provides a color-coded dose map on a patient-graphic model. The KAP is the integral of air kerma over the x-ray field and is usually measured with a transmission-ionization chamber that intercepts the entire x-ray beam. The DTS has been modified to determine KAP when there are beam non-uniformities that can be modeled. For example,more » the DTS includes models of the three compensation filters with tapered edges located in the collimator assembly of the Toshiba Infinix fluoroscopic C-Arm and can track their movement. To determine the air kerma after the filters, DTS includes transmission factors for the compensation filters as a function of kVp and beam filtration. A virtual KAP dosimeter is simulated in the DTS by an array of graphic vertices; the air kerma at each vertex is corrected by the field non-uniformity, which in this case is the attenuation factor for those rays which pass through the filter. The products of individual vertex air-kerma values for all vertices within the beam times the effective-area-per-vertex are summed for each x-ray pulse to yield the KAP per pulse and the cumulative KAP for the procedure is then calculated. Results: The KAP values estimated by DTS with the compensation filter inserted into the x-ray field agree within ± 6% with the values displayed on the fluoroscopy unit monitor, which are measured with a transmission chamber. Conclusion: The DTS can account for field non-uniformities such as result from the use of compensation filters in calculating KAP and can obviate the need for a KAP transmission ionization chamber. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

  10. A 150 year precipitation record preserved in lake sediments of Lake Gahai in the Qaidam Basin, northwest China

    NASA Astrophysics Data System (ADS)

    Li, X.

    2012-12-01

    A 150 year precipitation record preserved in lake sediments of Lake Gahai in the Qaidam Basin, northwest China Li Xiangzhong a, Liu Weiguoa, b a State Key Laboratory of Loess and Quaternary Geology, IEE, CAS, Xi'an, 710075, China b School of Human Settlement and Civil Engineering, Xi'an Jiaotong University, Xi'an, 710049, China Abstract Usually, the oxygen isotopic compositions of ostracods from the lake sediments are interpreted as changes in effective precipitation, temperature and evaporation/input water ratio in a sub-arid or arid area. Here, we compare a 150-year-long oxygen-isotope record that was derived from ostracod carbonate from the sediment core (in a seven-year resolution) of Lake Gahai in the Qaidam Basin with meteorological data (precipitation) and tree-ring evidence for changing precipitation. Our results show that the increased precipitation accompanied a shift to less positive δ18O values in the lake water, and hence of the ostracod shells, whereas decreased precipitation coincides with the opposite in Lake Gahai over the past ~150 years. The sole occurrence of the ostracod E. mareotica also indicates that the lake's salinity may have experienced no marked change over the past 150 years. Therefore, we conclude that the oxygen isotopic compositions of ostracod shells can be used to indicate changes in precipitation for paleoclimatic reconstruction over a short time scale in Lake Gahai. Keywords: oxygen isotope; ostracod; precipitation; Lake Gahai, Qaidam Basin

  11. How Plastics Work

    NASA Astrophysics Data System (ADS)

    Bloomfield, Louis

    2013-03-01

    We encounter plastics every day, but despite their widespread use, amazing range of properties, and basic scientific underpinnings, most physicists--like most people--know relatively little about plastics. In contrast to hard crystalline and amorphous solids (e.g., metals, salts, ceramics, and glasses), we take plastics for granted, select them carelessly, and examine them more closely only on a need-to-know basis. By ignoring plastics until we need them, however, we risk not knowing what we don't know and using the wrong ones. To repurpose a familiar advertisement, ``there's a plastic for that.'' This talk will review some of the basic physics and science of plastics. It will examine the roles of temperature, order, intermolecular forces, entanglements, and linkages in plastics, and how those issues affect the properties of a given plastic. We'll stop along the way to recognize a few of the more familiar plastics, natural and synthetic, and explain some of their mechanical, chemical, and optical properties. The talk will conclude by explaining the remarkable properties of a plastic that has been largely misunderstood since its discovery 70 years ago: Silly Putty.

  12. Our plastic age.

    PubMed

    Thompson, Richard C; Swan, Shanna H; Moore, Charles J; vom Saal, Frederick S

    2009-07-27

    Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation.

  13. Our plastic age

    PubMed Central

    Thompson, Richard C.; Swan, Shanna H.; Moore, Charles J.; vom Saal, Frederick S.

    2009-01-01

    Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation. PMID:19528049

  14. Plasticized phenolphthalein polycarbonate

    NASA Technical Reports Server (NTRS)

    Harrison, E. S.

    1976-01-01

    Phenolphthalein polycarbonate was successfully plasticized with polychlorinated biphenyls (e.g., Aroclor 1231) or tricresyl phosphate and cast from tetrahydrofuran to give clear films without loss of fire resistance. At loadings of 20 to 30 percent plasticizer the Tg was lowered to approximately 100 C which would render phenolphthalein polycarbonate easily moldable. Although these materials had some mechanical integrity as shown by their film forming ability, the room temperature toughness of the plasticized polymer was not significantly improved over unmodified polymer.

  15. Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on {sup 12}C

    SciTech Connect

    Chadwick, M.B.; Blann, M.; Cox, L.

    1995-04-11

    A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on {sup 12}C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements wheremore » they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A{le}and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV.« less

  16. Accuracy of Spencer-Attix cavity theory and calculations of fluence correction factors for the air kerma formalism

    SciTech Connect

    La Russa, D. J.; Rogers, D. W. O.

    EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for {sup 60}Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (K{sub fl}) by the presence of the cavity. The need for K{sub fl} corrections arises from the fact that the standard prescription for choosing the low-energy threshold {Delta}more » in the SA restricted stopping-power ratio consistently underestimates the values of {Delta} needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing {Delta}, but it is not clear how {Delta} can be calculated from first principles. Values of {Delta} required to avoid K{sub fl} corrections were found to be consistently higher than {Delta} values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of K{sub fl} have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%.« less

  17. Additives in plastics.

    PubMed Central

    Deanin, R D

    1975-01-01

    The polymers used in plastics are generally harmless. However, they are rarely used in pure form. In almost all commercial plastics, they are "compounded" with monomeric ingredients to improve their processing and end-use performance. In order of total volume used, these monomeric additives may be classified as follows: reinforcing fibers, fillers, and coupling agents; plasticizers; colorants; stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives); processing aids (lubricants, others, and flow controls); flame retardants, peroxides; and antistats. Some information is already available, and much more is needed, on potential toxicity and safe handling of these additives during processing and manufacture of plastics products. PMID:1175566

  18. Plastics and health risks.

    PubMed

    Halden, Rolf U

    2010-01-01

    By 2010, the worldwide annual production of plastics will surpass 300 million tons. Plastics are indispensable materials in modern society, and many products manufactured from plastics are a boon to public health (e.g., disposable syringes, intravenous bags). However, plastics also pose health risks. Of principal concern are endocrine-disrupting properties, as triggered for example by bisphenol A and di-(2-ethylhexyl) phthalate (DEHP). Opinions on the safety of plastics vary widely, and despite more than five decades of research, scientific consensus on product safety is still elusive. This literature review summarizes information from more than 120 peer-reviewed publications on health effects of plastics and plasticizers in lab animals and humans. It examines problematic exposures of susceptible populations and also briefly summarizes adverse environmental impacts from plastic pollution. Ongoing efforts to steer human society toward resource conservation and sustainable consumption are discussed, including the concept of the 5 Rs--i.e., reduce, reuse, recycle, rethink, restrain--for minimizing pre- and postnatal exposures to potentially harmful components of plastics.

  19. Biodegradation of plastics.

    PubMed

    Shimao, M

    2001-06-01

    Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. Recent work has included studies of the distribution of synthetic polymer-degrading microorganisms in the environment, the isolation of new microorganisms for biodegradation, the discovery of new degradation enzymes, and the cloning of genes for synthetic polymer-degrading enzymes.

  20. Pin-photodiode array for the measurement of fan-beam energy and air kerma distributions of X-ray CT scanners.

    PubMed

    Haba, Tomonobu; Koyama, Shuji; Aoyama, Takahiko; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao; Kameyama, Hiroshi; Tsutsumi, Yoshinori

    2016-07-01

    Patient dose estimation in X-ray computed tomography (CT) is generally performed by Monte Carlo simulation of photon interactions within anthropomorphic or cylindrical phantoms. An accurate Monte Carlo simulation requires an understanding of the effects of the bow-tie filter equipped in a CT scanner, i.e. the change of X-ray energy and air kerma along the fan-beam arc of the CT scanner. To measure the effective energy and air kerma distributions, we devised a pin-photodiode array utilizing eight channels of X-ray sensors arranged at regular intervals along the fan-beam arc of the CT scanner. Each X-ray sensor consisted of two plate type of pin silicon photodiodes in tandem - front and rear photodiodes - and of a lead collimator, which only allowed X-rays to impinge vertically to the silicon surface of the photodiodes. The effective energy of the X-rays was calculated from the ratio of the output voltages of the photodiodes and the dose was calculated from the output voltage of the front photodiode using the energy and dose calibration curves respectively. The pin-photodiode array allowed the calculation of X-ray effective energies and relative doses, at eight points simultaneously along the fan-beam arc of a CT scanner during a single rotation of the scanner. The fan-beam energy and air kerma distributions of CT scanners can be effectively measured using this pin-photodiode array. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  1. Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

    PubMed

    Wunderle, Kevin A; Rakowski, Joseph T; Dong, Frank F

    2016-05-08

    The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma-area product (Pk,a) over a broad spectrum of X-ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma-area product meters (KAP meters) to measure X-ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state-of-the-art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC deter-mined at 100 kVp with copper (Cu) in the beam resulted in a deviation of < 5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ± 35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (~ 55-60 kVp) and large amount of Cu filtration (~ 0.6-0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify.

  2. Track recording plastic compositions

    NASA Technical Reports Server (NTRS)

    Tarle, Gregory (Inventor)

    1983-01-01

    Improved nuclear track recording plastic compositions are provided which exhibit greatly decreased surface roughness when etched to produce visible tracks of energetic nuclear particles which have passed into and/or through said plastic. The improved compositions incorporate a small quantity of a phthalic acid ester into the major plastic component which is derived from the polymerization of monomeric di-ethylene glycol bis allyl carbonate. Di-substituted phthalic acid esters are preferred as the added component, with the further perference that the ester substituent has a chain length of 2 or more carbon atoms. The inclusion of the phthalic acid ester to an extent of from about 1-2% by weight of the plastic compositions is sufficient to drastically reduce the surface roughness ordinarily produced when the track recording plastic is contacted by etchants.

  3. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays.

    PubMed

    Burns, D T; Kessler, C; O'Brien, M; Minniti, R

    2012-01-01

    A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 10 3 , except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

  4. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the NIST, USA and the BIPM in medium-energy x-rays

    PubMed Central

    Burns, D T; Kessler, C; O’Brien, M; Minniti, R

    2017-01-01

    A key comparison has been made between the air-kerma standards of the NIST, USA and the BIPM in the medium-energy x–ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 103, except at 250 kV where the difference is 1.5 times the standard uncertainty. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. PMID:28966399

  5. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    SciTech Connect

    Crosbie, Jeffrey C.; Rogers, Peter A. W.; Stevenson, Andrew W.

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validatedmore » this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x

  6. 77 FR 54930 - Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A Subsidiary of Plastics...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-81,655] Carlyle Plastics and Resins, Formerly Known as Fortis Plastics, A Subsidiary of Plastics Acquisitions Inc., Including On-Site... to workers and former workers of workers of Fortis Plastics, a subsidiary of Plastics Acquisitions...

  7. Design, fabrication, and performance testing of a vacuum chamber for pulse compressor of a 150 TW Ti:sapphire laser

    NASA Astrophysics Data System (ADS)

    Tripathi, P. K.; Singh, Rajvir; Bhatnagar, V. K.; Sharma, S. D.; Sharma, Sanjay; Sisodia, B.; Yedle, K.; Kushwaha, R. P.; Sebastin, S.; Mundra, G.

    2012-11-01

    A vacuum chamber, to house the optical pulse compressor of a 150 TW Ti:sapphire laser system, has been designed, fabricated, and tested. As the intensity of the laser pulse becomes very high after pulse compression, there is phase distortion of the laser beam in air. Hence, the beam (after pulse compression) has to be transported in vacuum to avoid this distortion, which affects the laser beam focusability. A breadboard with optical gratings and reflective optics for compression of the optical pulse has to be kept inside the chamber. The chamber is made of SS 316L material in cuboidal shape with inside dimensions 1370×1030×650 mm3, with rectangular and circular demountable ports for entry and exit of the laser beam, evacuation, system cables, and ports to access optics mounted inside the chamber. The front and back sides of the chamber are kept demountable in order to insert the breadboard with optical components mounted on it. Leak tightness of 9×10-9 mbar-lit/sec in all the joints and ultimate vacuum of 6.5×10-6 mbar was achieved in the chamber using a turbo molecular pumping system. The paper describe details of the design/ features of the chamber, important procedure involved in machining, fabrication, processing and final testing.

  8. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the MKEH, Hungary and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Machula, G.

    2018-01-01

    A comparison of the standards for air kerma of the Hungarian Trade Licensing Office (MKEH), Hungary and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2016. The comparison result, evaluated as a ratio of the MKEH and the BIPM standards for air kerma, is 1.0047 with a combined standard uncertainty of 1.9 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2.6 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the IST-LPSR, Portugal and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Cardoso, J.

    2018-01-01

    A comparison of the standards for air kerma of the Instituto Superior Técnico, Laboratório de Proteção e Segurança Radiológica (IST-LPSR), Portugal and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in December 2015. The comparison result, evaluated as a ratio of the IST-LPSR and the BIPM standards for air kerma, is 1.0026 with a combined standard uncertainty of 1.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 1.1 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the SMU, Slovakia and the BIPM in 137Cs gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Durný, N.

    2018-01-01

    The first direct comparison of the standards for air kerma of the Slovak Institute of Metrology (SMU), Slovakia and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in June 2017. The comparison result, evaluated as a ratio of the SMU and the BIPM standards for air kerma, is 1.0051 with a combined standard uncertainty of 2.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the SMU, Slovakia and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D.; Durný, N.

    2018-01-01

    A key comparison of the standards for air kerma of the Slovak Institute of Metrology (SMU), Slovakia and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in June 2017. The comparison result, evaluated as a ratio of the SMU and the BIPM standards for air kerma, is 1.0042 with a combined standard uncertainty of 2.7 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 2 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Badiger, N. M.

    2014-11-01

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

  13. Physics in Plastics Technology.

    ERIC Educational Resources Information Center

    Thomas, Ken

    1980-01-01

    Discusses the increasing role of the physicist in plastics technology. Relationships of molecular structure to material behavior, design which is related to the material, and the practical problems of fabricating a material into an article are included. (HM)

  14. Stem cell plasticity.

    PubMed

    Lakshmipathy, Uma; Verfaillie, Catherine

    2005-01-01

    The central dogma in stem cell biology has been that cells isolated from a particular tissue can renew and differentiate into lineages of the tissue it resides in. Several studies have challenged this idea by demonstrating that tissue specific cell have considerable plasticity and can cross-lineage restriction boundary and give rise to cell types of other lineages. However, the lack of a clear definition for plasticity has led to confusion with several reports failing to demonstrate that a single cell can indeed differentiate into multiple lineages at significant levels. Further, differences between results obtained in different labs has cast doubt on some results and several studies still await independent confirmation. In this review, we critically evaluate studies that report stem cell plasticity using three rigid criteria to define stem cell plasticity; differentiation of a single cell into multiple cell lineages, functionality of differentiated cells in vitro and in vivo, robust and persistent engraft of transplanted cells.

  15. Art and Plastic Surgery.

    PubMed

    Fernandes, Julio Wilson; Metka, Susanne

    2016-04-01

    The roots of science and art of plastic surgery are very antique. Anatomy, drawing, painting, and sculpting have been very important to the surgery and medicine development over the centuries. Artistic skills besides shape, volume, and lines perception can be a practical aid to the plastic surgeons' daily work. An overview about the interactions between art and plastic surgery is presented, with a few applications to rhinoplasty, cleft lip, and other reconstructive plastic surgeries. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

  16. A Plastic Menagerie

    ERIC Educational Resources Information Center

    Hadley, Mary Jane

    2010-01-01

    Bobble heads had become quite popular, depicting all sorts of sports figures, animals, and even presidents. In this article, the author describes how her fourth graders made bobble head sculptures out of empty plastic drink bottles. (Contains 1 online resource.)

  17. Dreaming in plastic

    NASA Astrophysics Data System (ADS)

    Korzhov, Marianna; Andelman, David; Shikler, Rafi

    2008-07-01

    Plastic is one of the most versatile materials available. It is cheap, flexible and easy to process, and as a result it is all around us - from our computer keyboards to the soles of our shoes. One of its most common applications is as an insulating coating for electric wires; indeed, plastic is well known for its insulating characteristics. It came as something of a surprise, therefore, when in the late 1970s a new generation of plastics was discovered that displayed exactly the opposite behaviour - the ability to conduct electricity. In fact, plastics can be made with a whole range of conductivities - there are polymer materials that behave like semiconductors and there are those that can conduct as well as metals. This discovery sparked a revolution in the electronics community, and three decades of research effort is now yielding a range of stunning new applications for this ubiquitous material.

  18. Laser cutting plastic materials

    NASA Astrophysics Data System (ADS)

    Vancleave, R. A.

    1980-08-01

    A 1000 watt CO2 laser was demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics were laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass reinforced laminates, Kevlar/epoxy composites, fiberglass reinforced phenolics, nylon/epoxy laminates, ceramics, and disposal tooling made from acrylic.

  19. The Need for Plastics Education.

    ERIC Educational Resources Information Center

    Society of Plastics Engineers, Inc., Stamford, CT.

    In view of a lack of trained personnel in the industry, the Plastics Education Foundation proposes that educators (1) add more plastics programs, (2) establish plastics engineering degrees at appropriate 4-year institutions, (3) add plastics processing technology to current engineering curricula, and (4) interest younger students in courses and/or…

  20. Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality

    NASA Astrophysics Data System (ADS)

    Helge Østerås, Bjørn; Skaane, Per; Gullien, Randi; Catrine Trægde Martinsen, Anne

    2018-02-01

    The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra™). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra™. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

  1. SU-G-IeP3-01: Better Kerma-Area-Product (KAP) Estimation Using the System Parameters in Radiography and Fluoroscopy

    SciTech Connect

    Kim, D; MacDougall, R

    2016-06-15

    Purpose: Accurate values for Kerma-Area-Product (KAP) are needed for patient dosimetry and quality control for exams utilizing radiographic and/or fluoroscopic imaging. The KAP measured using a typical direct KAP meter built with parallel-plate transmission ionization chamber is not precise and depends on the energy spectrum of diagnostic x-rays. This study compared the accuracy and reproducibility of KAP derived from system parameters with values measured with a direct KAP meter. Methods: IEC tolerance for displayed KAP is specified up to ± 35% above 2.5 Gy-cm{sup 2} and manufacturer’s specifications are typically ± 25%. KAP values from the direct KAP meter driftsmore » with time leading to replacement or re-calibration. More precise and consistent KAP is achievable utilizing a database of known radiation output for various system parameters. The integrated KAP meter was removed from a radiography system. A total of 48 measurements of air kerma were acquired at x-ray tube potential from 40 to 150 kVp with 10 kVp increment using ion chamber type external dosimeter at free-in-air geometry for four different types of filter combinations following the manufacturer’s service procedure. These data were used to create updated correction factors that determine air kerma computationally for given system parameters. Results of calculated KAP were evaluated against results using a calibrated ion chamber based dosimeter and a computed radiography imaging plate to measure x-ray field size. Results: The accuracy of calculated KAP from the system parameters was better within 4% deviation in all diagnostic x-ray tube potentials tested from 50 to 140 kVp. In contrast, deviations of up to 25% were measured from KAP displayed from the direct KAP meter. Conclusion: The “calculated KAP” approach provides the nominal advantage of improved accuracy and precision of displayed KAP as well as reduced cost of calibrating or replacing integrated KAP meters.« less

  2. Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality.

    PubMed

    Østerås, Bjørn Helge; Skaane, Per; Gullien, Randi; Martinsen, Anne Catrine Trægde

    2018-01-25

    The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra ™ ). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra ™ . AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

  3. Plastic Organic Scintillator Chemistry

    NASA Astrophysics Data System (ADS)

    Brightwell, C. R.; Temanson, E. S.; Febbraro, M. T.

    2017-09-01

    Due to their high light output, quick decay time, affordability, durability and ability to be molded, plastic organic scintillators are increasingly becoming a more viable method of particle detection. Since the plastic is composed entirely of single molecular chains with repeating units, scintillating properties remain stable despite changes in experimental conditions. Different scintillating plastics can be modified and tailored to suit specific experiments depending on a variety of requirements such as light output, scintillating wavelength, and PMT compatibility. The synthesis chemistry of a recent but well-known scintillating polyester, polyethylene naphthalate (PEN) will be presented to demonstrate how plastic organic scintillators can be modified for different particle detection experiments. PEN has been successfully synthesized at ORNL, and procedures are currently being investigated to modify PEN using different reactants and catalysts. The goal is to achieve a transparent scintillating plastic with an incorporated wavelength shifter in the chain that scintillates with a wavelength around 440 nm. The status of this project will be presented. This research is supported by the U. S. Department of Energy Office of Science.

  4. The plasticity of clays

    USGS Publications Warehouse

    Group, F.F.

    1905-01-01

    (1) Sand injures plasticity little at first because the grains are suspended in a plastic mass. It is only when grains are abundant enough to come in contact with their neighbors, that the effect becomes serious, and then both strength and amount of possible flow are injured. (2) Certain rare organic colloids increase the plasticity by rendering the water viscous. (3) Fineness also tends to increase plasticity. (4) Plane surfaces (plates) increase the amount of possible flow. They also give a chance for lubrication by thinner films, thus increasing the friction of film, and the strength of the whole mass. The action of plates is thus twofold ; but fineness may be carried to such an extent as to break up plate-like grains into angular fragments. The beneficial effects of plates are also decreased by the fact that each is so closely surrounded by others in the mass. (5) Molecular attraction is twofold in increasing plasticity. As the attraction increases, the coherence and strength of the mass increase, and the amount of possible deformation before crumbling also increases. Fineness increases this action by requiring more water. Colloids and crystalloids in solution may also increase the attraction. It is thus seen to be more active than any other single factor.

  5. Cortical Plasticity in Depression

    PubMed Central

    Cantone, Mariagiovanna; Bramanti, Alessia; Pennisi, Manuela; Bramanti, Placido; Pennisi, Giovanni; Bella, Rita

    2017-01-01

    Neural plasticity is considered the neurophysiological correlate of learning and memory, although several studies have also noted that it plays crucial roles in a number of neurological and psychiatric diseases. Indeed, impaired brain plasticity may be one of the pathophysiological mechanisms that underlies both cognitive decline and major depression. Moreover, a degree of cognitive impairment is frequently observed throughout the clinical spectrum of mood disorders, and the relationship between depression and cognition is often bidirectional. However, most evidence for dysfunctional neural plasticity in depression has been indirect. Transcranial magnetic stimulation has emerged as a noninvasive tool for investigating several parameters of cortical excitability with the aim of exploring the functions of different neurotransmission pathways and for probing in vivo plasticity in both healthy humans and those with pathological conditions. In particular, depressed patients exhibit a significant interhemispheric difference in motor cortex excitability, an imbalanced inhibitory or excitatory intracortical neurochemical circuitry, reduced postexercise facilitation, and an impaired long-term potentiation-like response to paired-associative transcranial magnetic stimulation, and these symptoms may indicate disrupted plasticity. Research aimed at disentangling the mechanism by which neuroplasticity plays a role in the pathological processes that lead to depression and evaluating the effects of modulating neuroplasticity are needed for the field to facilitate more powerful translational research studies and identify novel therapeutic targets. PMID:28629225

  6. COMPARISON STUDY OF VARIOUS PLASTICS AS THE WALL MATERIAL OF THGEM-BASED MICRODOSEMETERS FOR FAST NEUTRON MEASUREMENTS.

    PubMed

    Moslehi, A; Raisali, G; Lamehi, M

    2017-04-15

    To find appropriate substitutions for the expensive plastics of A-150 and rexolite used in the construction of thick gas electron multiplier (THGEM)-based tissue-equivalent proportional counters, in the present work, the responses of a THGEM-based microdosimetric detector made of A-150 and rexolite and three others composed of plexiglas (PMMA), polyethylene and polystyrene plastics as the wall materials have been compared. Lineal energy distribution, frequency-averaged lineal energy, dose-averaged lineal energy, mean quality factor and dose-equivalent for 0.1, 1 and 10 MeV neutrons and also for 241Am-Be neutrons are calculated using Geant4 simulation toolkit. Frequency-averaged lineal energy, dose-averaged lineal energy, mean quality factor and dose-equivalent values for all plastics are found similar. In addition, the response of an indigenously constructed microdosemeter with PMMA walls is also measured for 241Am-Be neutrons. The experimental results are in good agreement with the simulation predictions. Conclusively, it was found that the three considered plastics can be used as good candidates instead of A-150 and rexolite plastics in fast neutron microdosimetry. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Consumer hazards of plastics.

    PubMed Central

    Wiberg, G S

    1976-01-01

    The modern consumer is exposed to a wide variety of plastic and rubber products in his day to day life: at home, work, school, shopping, recreation and play, and transport. A large variety of toxic sequellae have resulted from untoward exposures by many different routes: oral, dermal, inhalation, and parenteral. Toxic change may result from the plastic itself, migration of unbound components and additives, chemical decomposition or toxic pyrolysis products. The type of damage may involve acute poisoning, chronic organ damage, reproductive disorders, and carcinogenic, mutagenic and teratogenic episodes. Typical examples for all routes are cited along with the activites of Canadian regulatory agencies to reduce both the incidence and severity of plastic-induced disease. PMID:1026409

  8. Comparison of the NIST and BIPM Air-Kerma Standards for Measurements in the Low-Energy X-Ray Range

    PubMed Central

    Burns, D. T.; Lamperti, P.; O’Brien, M.

    1999-01-01

    A direct comparison was made between the air-kerma standards used for the measurement of low-energy x rays at the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison was carried out at the BIPM using the BIPM reference beam qualities in the range from 10 kV to 100 kV. The results show the standards to be in agreement to around 0.5 % at reference beam qualities up to 50 kV and at 100 kV. The result at the 80 kV beam quality is less favorable, with agreement at the 1 % level.

  9. KEY COMPARISON Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 137Cs gamma rays

    NASA Astrophysics Data System (ADS)

    Allisy-Roberts, P. J.; Kessler, C.; Toni, M.; Bovi, M.

    2010-01-01

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 137Cs radiation in 1998. The comparison result, updated for changes in the standards in 2003 and 2009, is 0.9927 (0.0067) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the uncertainties. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  10. Determination of the Kwall correction factor for a cylindrical ionization chamber to measure air-kerma in 60Co gamma beams.

    PubMed

    Laitano, R F; Toni, M P; Pimpinella, M; Bovi, M

    2002-07-21

    The factor Kwall to correct for photon attenuation and scatter in the wall of ionization chambers for 60Co air-kerma measurement has been traditionally determined by a procedure based on a linear extrapolation of the chamber current to zero wall thickness. Monte Carlo calculations by Rogers and Bielajew (1990 Phys. Med. Biol. 35 1065-78) provided evidence, mostly for chambers of cylindrical and spherical geometry, of appreciable deviations between the calculated values of Kwall and those obtained by the traditional extrapolation procedure. In the present work an experimental method other than the traditional extrapolation procedure was used to determine the Kwall factor. In this method the dependence of the ionization current in a cylindrical chamber was analysed as a function of an effective wall thickness in place of the physical (radial) wall thickness traditionally considered in this type of measurement. To this end the chamber wall was ideally divided into distinct regions and for each region an effective thickness to which the chamber current correlates was determined. A Monte Carlo calculation of attenuation and scatter effects in the different regions of the chamber wall was also made to compare calculation to measurement results. The Kwall values experimentally determined in this work agree within 0.2% with the Monte Carlo calculation. The agreement between these independent methods and the appreciable deviation (up to about 1%) between the results of both these methods and those obtained by the traditional extrapolation procedure support the conclusion that the two independent methods providing comparable results are correct and the traditional extrapolation procedure is likely to be wrong. The numerical results of the present study refer to a cylindrical cavity chamber like that adopted as the Italian national air-kerma standard at INMRI-ENEA (Italy). The method used in this study applies, however, to any other chamber of the same type.

  11. Plastics in Perspective.

    ERIC Educational Resources Information Center

    Bergandine, David R.; Holm, D. Andrew

    The materials in this curriculum supplement, developed for middle school or high school science classes, present solid waste problems related to plastics. The set of curriculum materials is divided into two units to be used together or independently. Unit I begins by comparing patterns in solid waste from 1960 to 1990 and introducing methods for…

  12. New plastic recycling technology

    EPA Science Inventory

    Greater than 60% of the total plastic content of municipal solid waste is comprised of polyolefins (high-density, low-density, and linear polyethylene and polypropylene. Polyethylene (PE) is the largest-volume component but presents a challenge due to the absence of low-energy de...

  13. Individual differences in behavioural plasticities.

    PubMed

    Stamps, Judy A

    2016-05-01

    Interest in individual differences in animal behavioural plasticities has surged in recent years, but research in this area has been hampered by semantic confusion as different investigators use the same terms (e.g. plasticity, flexibility, responsiveness) to refer to different phenomena. The first goal of this review is to suggest a framework for categorizing the many different types of behavioural plasticities, describe examples of each, and indicate why using reversibility as a criterion for categorizing behavioural plasticities is problematic. This framework is then used to address a number of timely questions about individual differences in behavioural plasticities. One set of questions concerns the experimental designs that can be used to study individual differences in various types of behavioural plasticities. Although within-individual designs are the default option for empirical studies of many types of behavioural plasticities, in some situations (e.g. when experience at an early age affects the behaviour expressed at subsequent ages), 'replicate individual' designs can provide useful insights into individual differences in behavioural plasticities. To date, researchers using within-individual and replicate individual designs have documented individual differences in all of the major categories of behavioural plasticities described herein. Another important question is whether and how different types of behavioural plasticities are related to one another. Currently there is empirical evidence that many behavioural plasticities [e.g. contextual plasticity, learning rates, IIV (intra-individual variability), endogenous plasticities, ontogenetic plasticities) can themselves vary as a function of experiences earlier in life, that is, many types of behavioural plasticity are themselves developmentally plastic. These findings support the assumption that differences among individuals in prior experiences may contribute to individual differences in behavioural

  14. Plastics for Elementary School Children

    ERIC Educational Resources Information Center

    Hanson, Jack

    1977-01-01

    Describes three plastics projects (which involve making a styrene fishing bobber, an acrylic salad fork and spoon set, and acetate shrink art) designed to provide elementary level students an opportunity to work with plastics and to learn about careers in plastics production and distribution. (TA)

  15. Respiratory Muscle Plasticity

    PubMed Central

    Gransee, Heather M.; Mantilla, Carlos B.; Sieck, Gary C.

    2014-01-01

    Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. As such, respiratory muscle is in a constant state of remodeling, and the basis of muscle’s plasticity is its ability to change protein expression and resultant protein balance in response to varying environmental conditions. Here, we will describe the changes of respiratory muscle imposed by extrinsic changes in mechanical load, activity, and innervation. Although there is a large body of literature on the structural and functional plasticity of respiratory muscles, we are only beginning to understand the molecular-scale protein changes that contribute to protein balance. We will give an overview of key mechanisms regulating protein synthesis and protein degradation, as well as the complex interactions between them. We suggest future application of a systems biology approach that would develop a mathematical model of protein balance and greatly improve treatments in a variety of clinical settings related to maintaining both muscle mass and optimal contractile function of respiratory muscles. PMID:23798306

  16. Adult Visual Cortical Plasticity

    PubMed Central

    Gilbert, Charles D.; Li, Wu

    2012-01-01

    The visual cortex has the capacity for experience dependent change, or cortical plasticity, that is retained throughout life. Plasticity is invoked for encoding information during perceptual learning, by internally representing the regularities of the visual environment, which is useful for facilitating intermediate level vision - contour integration and surface segmentation. The same mechanisms have adaptive value for functional recovery after CNS damage, such as that associated with stroke or neurodegenerative disease. A common feature to plasticity in primary visual cortex (V1) is an association field that links contour elements across the visual field. The circuitry underlying the association field includes a plexus of long range horizontal connections formed by cortical pyramidal cells. These connections undergo rapid and exuberant sprouting and pruning in response to removal of sensory input, which can account for the topographic reorganization following retinal lesions. Similar alterations in cortical circuitry may be involved in perceptual learning, and the changes observed in V1 may be representative of how learned information is encoded throughout the cerebral cortex. PMID:22841310

  17. Plastic footwear for leprosy.

    PubMed

    Antia, N H

    1990-03-01

    The anaesthetic foot in leprosy poses the most major problem in the rehabilitation of its patients. Various attempts have been made to produce protective footwear such as the microcellular rubber-car-tyre sandals. Unfortunately these attempts have had little success on a large scale because of the inability to produce them in large numbers and the stigma attached to such unusual footwear. While such footwear may be superior to the 'tennis' shoe in protecting the foot from injury by the penetration of sharp objects, it fails to distribute the weight-bearing forces which is the major cause of plantar damage and ulceration in the anaesthetic foot. This can be achieved by providing rigidity to the sole, as demonstrated by the healing of ulcers in plaster of paris casts or the rigid wooden clog. A new type of moulded plastic footwear has been evolved in conjunction with the plastic footwear industry which provides footwear that can be mass produced at a low price and which overcomes the stigma of leprosy. Controlled rigidity is provided by the incorporation of a spring steel shank between the sponge insole and the hard wearing plastic sole. Trials have demonstrated both the acceptability of the footwear and its protective effects as well as its hard wearing properties.

  18. New perspectives in plastic biodegradation.

    PubMed

    Sivan, Alex

    2011-06-01

    During the past 50 years new plastic materials, in various applications, have gradually replaced the traditional metal, wood, leather materials. Ironically, the most preferred property of plastics--durability--exerts also the major environmental threat. Recycling has practically failed to provide a safe solution for disposal of plastic waste (only 5% out of 1 trillion plastic bags, annually produced in the US alone, are being recycled). Since the most utilized plastic is polyethylene (PE; ca. 140 million tons/year), any reduction in the accumulation of PE waste alone would have a major impact on the overall reduction of the plastic waste in the environment. Since PE is considered to be practically inert, efforts were made to isolate unique microorganisms capable of utilizing synthetic polymers. Recent data showed that biodegradation of plastic waste with selected microbial strains became a viable solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Interfacial interactions between plastic particles in plastics flotation.

    PubMed

    Wang, Chong-qing; Wang, Hui; Gu, Guo-hua; Fu, Jian-gang; Lin, Qing-quan; Liu, You-nian

    2015-12-01

    Plastics flotation used for recycling of plastic wastes receives increasing attention for its industrial application. In order to study the mechanism of plastics flotation, the interfacial interactions between plastic particles in flotation system were investigated through calculation of Lifshitz-van der Waals (LW) function, Lewis acid-base (AB) Gibbs function, and the extended Derjaguin-Landau-Verwey-Overbeek potential energy profiles. The results showed that van der Waals force between plastic particles is attraction force in flotation system. The large hydrophobic attraction, caused by the AB Gibbs function, is the dominant interparticle force. Wetting agents present significant effects on the interfacial interactions between plastic particles. It is found that adsorption of wetting agents promotes dispersion of plastic particles and decreases the floatability. Pneumatic flotation may improve the recovery and purity of separated plastics through selective adsorption of wetting agents on plastic surface. The relationships between hydrophobic attraction and surface properties were also examined. It is revealed that there exists a three-order polynomial relationship between the AB Gibbs function and Lewis base component. Our finding provides some insights into mechanism of plastics flotation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Radiological investigations at the "Taiga" nuclear explosion site, part II: man-made γ-ray emitting radionuclides in the ground and the resultant kerma rate in air.

    PubMed

    Ramzaev, V; Repin, V; Medvedev, A; Khramtsov, E; Timofeeva, M; Yakovlev, V

    2012-07-01

    Samples of soil and epigeic lichens were collected from the "Taiga" peaceful nuclear explosion site (61.30°N 56.60°E, the Perm region, Russia) in 2009 and analyzed using high resolution γ-ray spectrometry. For soil samples obtained at six different plots, two products of fission ((137)Cs and (155)Eu), five products of neutron activation ((60)Co, (94)Nb, (152)Eu, (154)Eu, (207)Bi) and (241)Am have been identified and quantified. The maximal activity concentrations of (60)Co, (137)Cs, and (241)Am for the soils samples were measured as 1650, 7100, and 6800 Bq kg(-1) (d.w.), respectively. The deposit of (137)Cs for the top 20 cm of soil on the tested plots at the "Taiga" site ranged from 30 to 1020 kBq m(-2); the maximal value greatly (by almost 3 orders of magnitude) exceeded the regional background (from global fallout) level of 1.4 kBq m(-2). (137)Cs contributes approximately 57% of the total ground inventory of the man-made γ-ray emitters for the six plots tested at the "Taiga" site. The other major radionuclides -(241)Am and (60)Co, constitute around 40%. Such radionuclides as (60)Co, (137)Cs, (241)Am, and (207)Bi have also been determined for the epigeic lichens (genera Cladonia) that colonized certain areas at the ground lip produced by the "Taiga" explosion. Maximal activity concentrations (up to 80 Bq kg(-1) for (60)Co, 580 Bq kg(-1) for (137)Cs, 200 Bq kg(-1) for (241)Am, and 5 Bq kg(-1) for (207)Bi; all are given in terms of d.w.) have been detected for the lower dead section of the organisms. The air kerma rates associated with the anthropogenic sources of gamma radiation have been calculated using the data obtained from the laboratory analysis. For the six plots tested, the kerma rates ranged from 50 to 1200 nGy h(-1); on average, 51% of the dose can be attributed to (137)Cs and 45% to (60)Co. These estimates agree reasonably well with the results of the in situ measurements made during our field survey of the "Taiga" site in August

  1. Abiotic degradation of plastic films

    NASA Astrophysics Data System (ADS)

    Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

    2017-01-01

    Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

  2. Plastics in the Marine Environment

    NASA Astrophysics Data System (ADS)

    Law, Kara Lavender

    2017-01-01

    Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence—albeit limited—of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

  3. Plastics in the Marine Environment.

    PubMed

    Law, Kara Lavender

    2017-01-03

    Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence-albeit limited-of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

  4. Use of recycled plastics in wood plastic composites - a review.

    PubMed

    Kazemi Najafi, Saeed

    2013-09-01

    The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Direct liquefaction of plastics and coprocessing of coal with plastics

    SciTech Connect

    Huffman, G.P.; Feng, Z.; Mahajan, V.

    1995-12-31

    The objectives of this work were to optimize reaction conditions for the direct liquefaction of waste plastics and the coprocessing of coal with waste plastics. In previous work, the direct liquefaction of medium and high density polyethylene (PE), polypropylene (PPE), poly(ethylene terephthalate) (PET), and a mixed plastic waste, and the coliquefaction of these plastics with coals of three different ranks was studied. The results established that a solid acid catalyst (HZSM-5 zeolite) was highly active for the liquefaction of the plastics alone, typically giving oil yields of 80-95% and total conversions of 90-100% at temperatures of 430-450 {degrees}C. In themore » coliquefaction experiments, 50:50 mixtures of plastic and coal were used with a tetralin solvent (tetralin:solid = 3:2). Using approximately 1% of the HZSM-5 catalyst and a nanoscale iron catalyst, oil yields of 50-70% and total conversion of 80-90% were typical. In the current year, further investigations were conducted of the liquefaction of PE, PPE, and a commingled waste plastic obtained from the American Plastics Council (APC), and the coprocessing of PE, PPE and the APC plastic with Black Thunder subbituminous coal. Several different catalysts were used in these studies.« less

  6. Important comments on KERMA factors and DPA cross-section data in ACE files of JENDL-4.0, JEFF-3.2 and ENDF/B-VII.1

    NASA Astrophysics Data System (ADS)

    Konno, Chikara; Tada, Kenichi; Kwon, Saerom; Ohta, Masayuki; Sato, Satoshi

    2017-09-01

    We have studied reasons of differences of KERMA factors and DPA cross-section data among nuclear data libraries. Here the KERMA factors and DPA cross-section data included in the official ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 are examined in more detail. As a result, it is newly found out that the KERMA factors and DPA cross-section data of a lot of nuclei are different among JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 and reasons of the differences are the followings: 1) large secondary particle production yield, 2) no secondary gamma data, 3) secondary gamma data in files12-15 mt = 3, 4) mt = 103-107 data without mt = 600 s-800 s data in file6. The issue 1) is considered to be due to nuclear data, while the issues 2)-4) seem to be due to NJOY. The ACE files of JENDL-4.0, ENDF/B-VII.1 and JEFF-3.2 with these problems should be revised after correcting wrong nuclear data and NJOY problems.

  7. The commercialization of plastic surgery.

    PubMed

    Swanson, Eric

    2013-09-01

    The last decade has brought a major challenge to the traditional practice of plastic surgery from corporations that treat plastic surgery as a commercial product and market directly to the public. This corporate medicine model may include promotion of a trademarked procedure or device, national advertising that promises stunning results, sales consultants, and claims of innovation, superiority, and improved safety. This article explores the ethics of this business practice and whether corporate medicine is a desirable model for patients and plastic surgeons.

  8. Americium behaviour in plastic vessels.

    PubMed

    Legarda, F; Herranz, M; Idoeta, R; Abelairas, A

    2010-01-01

    The adsorption of (241)Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of (241)Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of (241)Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification. Copyright 2009 Elsevier Ltd. All rights reserved.

  9. Plastics recycling: challenges and opportunities.

    PubMed

    Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

    2009-07-27

    Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3-4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

  10. Public perception of Plastic Surgery.

    PubMed

    de Blacam, Catherine; Kilmartin, Darren; Mc Dermott, Clodagh; Kelly, Jack

    2015-02-01

    Public perception of Plastic Surgery is strongly influenced by the media and may not reflect the broad scope of work within the speciality. The aim of this study was to provide an assessment of the general public's perception of plastic surgical practice and to report the perceived importance of Plastic Surgery relative to other specialities working within a large tertiary referral centre. 899 members of the public who attended our Emergency Department completed a questionnaire where they matched eight surgical specialities with 30 operative procedures and ranked the importance of 30 different hospital specialities using a Likert scale. The majority of respondents correctly identified plastic surgeons as performing each of the cosmetic procedures listed (abdominoplasty 63.7%; breast augmentation 59.1%; facelift 61.35%; liposuction 59.7%). Plastic Surgery was identified as the primary speciality involved in breast reconstruction (49.3%) and burns surgery (43.0%). There was poor understanding of the role of plastic surgeons in hand surgery, with only 4.7% of respondents attributing tendon repair to plastic surgeons. Plastic Surgery ranked lowest of 30 specialities in terms of importance in providing care for patients within the hospital. Plastic Surgery is often misunderstood within the wider community and misconceptions reflect the influence of the media in highlighting certain aspects of the speciality. It behoves our professional organisations to highlight the importance of Plastic and Reconstructive Surgery within major tertiary referral centres. Copyright © 2014 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Plastics recycling: challenges and opportunities

    PubMed Central

    Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

    2009-01-01

    Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3–4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

  12. Cooperativity in plastic crystals

    NASA Astrophysics Data System (ADS)

    Pieruccini, Marco; Tombari, Elpidio

    2018-03-01

    A statistical mechanical model previously adopted for the analysis of the α -relaxation in structural glass formers is rederived within a general theoretical framework originally developed for systems approaching the ideal glassy state. The interplay between nonexponentiality and cooperativity is reconsidered in the light of energy landscape concepts. The method is used to estimate the cooperativity in orientationally disordered crystals, either from the analysis of literature data on linear dielectric response or from the enthalpy relaxation function obtained by temperature-modulated calorimetry. Knowledge of the specific heat step due to the freezing of the configurational or conformational modes at the glass transition is needed in order to properly account for the extent to which the relaxing system deviates from equilibrium during the rearrangement processes. A number of plastic crystals have been analyzed, and relatively higher cooperativities are found in the presence of hydrogen bonding interaction.

  13. Plastic surgery in the press.

    PubMed

    Reid, A J; Malone, P S C

    2008-08-01

    The media play a vital role in public education. The predominant image they portray of plastic and reconstructive surgery is that of cosmetic surgery, whilst the specialty's true scope is often misrepresented. The aim was to evaluate portrayal of plastic surgery in the national newspapers. LexisNexis Professional search engine was used to retrieve articles from all UK newspapers published in 2006 that contained the term 'plastic surgery' and each article was analysed. Of 1191 articles, 89% used the term 'plastic surgery' in the context of cosmetic surgery and only 10% referred to reconstructive work. There were 197 feature articles on cosmetic surgery and 52% of them included a quote from the medical profession. If the quoted doctor was on the UK General Medical Council (GMC) specialist register for plastic surgery, it was significantly more likely that a potential problem or complication associated with cosmetic surgery would be mentioned (p= 0.015). The vast majority of newspaper articles refer only to the cosmetic component of plastic surgery. When quoted, doctors on the GMC specialist register for plastic surgery provide a more balanced view of cosmetic surgery. Further initiative is needed to portray the full scope of plastic and reconstructive surgery to the general public.

  14. Plastics & Composites Technology Needs Assessment.

    ERIC Educational Resources Information Center

    Oakland Community Coll., Farmington, MI. Office of Institutional Planning and Analysis.

    In 1991, a study was conducted by Oakland Community College (OCC) to evaluate the need for a proposed plastics and composites technology program for design engineers. General information was obtained through a literature search, from the Society of the Plastics Industry, Inc., the Michigan Employment Security Commission, and interviews with…

  15. Plastics to fuel: A review

    USDA-ARS?s Scientific Manuscript database

    This paper reviews recent developments in catalytic and non-catalytic degradation of waste plastics into fuels. Thermal degradation decomposes plastic into three fractions: gas, crude oil, and solid residue. Crude oil from non-catalytic pyrolysis is usually composed of higher boiling point hydrocarb...

  16. What do plastic surgeons do?

    PubMed

    Park, A J; Scerri, G V; Benamore, R; McDiarmid, J G; Lamberty, B G

    1998-06-01

    The image of plastic surgery as portrayed by the media is of concern to all plastic surgeons. In order to assess knowledge about the specialty, a questionnaire was devised and given to five groups of participants: general practitioners, medical students, nurses, plastic surgical out-patient attendees, and the general public. The results revealed that general practitioners, nurses and medical students in the Cambridge area are, on the whole, knowledgeable about the role of plastic surgery. However, the general public are not so well educated and 23.7% of them could not think of five conditions treated by plastic surgeons, and felt that burns and cosmetic problems were the commonest conditions dealt with. Improved liaison with general practitioners, other specialties and more teaching of undergraduates, coupled with more effective promotion of the skills on offer might permit better use to be made of the specialty.

  17. Biodegradability of degradable plastic waste.

    PubMed

    Agamuthu, P; Faizura, Putri Nadzrul

    2005-04-01

    Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

  18. Comparing Hp(3) evaluated from the conversion coefficients from air kerma to personal dose equivalent for eye lens dosimetry calibrated on a new cylindrical PMMA phantom

    NASA Astrophysics Data System (ADS)

    Esor, J.; Sudchai, W.; Monthonwattana, S.; Pungkun, V.; Intang, A.

    2017-06-01

    Based on a new occupational dose limit recommended by ICRP (2011), the annual dose limit for the lens of the eye for workers should be reduced from 150 mSv/y to 20 mSv/y averaged over 5 consecutive years in which no single year exceeding 50 mSv. This new dose limit directly affects radiologists and cardiologists whose work involves high radiation exposure over 20 mSv/y. Eye lens dosimetry (Hp(3)) has become increasingly important and should be evaluated directly based on dosimeters that are worn closely to the eye. Normally, Hp(3) dose algorithm was carried out by the combination of Hp(0.07) and Hp(10) values while dosimeters were calibrated on slab PMMA phantom. Recently, there were three reports from European Union that have shown the conversion coefficients from air kerma to Hp(3). These conversion coefficients carried out by ORAMED, PTB and CEA Saclay projects were performed by using a new cylindrical head phantom. In this study, various delivered doses were calculated using those three conversion coefficients while nanoDot, small OSL dosimeters, were used for Hp(3) measurement. These calibrations were performed with a standard X-ray generator at Secondary Standard Dosimetry Laboratory (SSDL). Delivered doses (Hp(3)) using those three conversion coefficients were compared with Hp(3) from nanoDot measurements. The results showed that percentage differences between delivered doses evaluated from the conversion coefficient of each project and Hp(3) doses evaluated from the nanoDots were found to be not exceeding -11.48 %, -8.85 % and -8.85 % for ORAMED, PTB and CEA Saclay project, respectively.

  19. A radiation quality correction factor k for well-type ionization chambers for the measurement of the reference air kerma rate of (60)Co HDR brachytherapy sources.

    PubMed

    Schüller, Andreas; Meier, Markus; Selbach, Hans-Joachim; Ankerhold, Ulrike

    2015-07-01

    The aim of this study was to investigate whether a chamber-type-specific radiation quality correction factor kQ can be determined in order to measure the reference air kerma rate of (60)Co high-dose-rate (HDR) brachytherapy sources with acceptable uncertainty by means of a well-type ionization chamber calibrated for (192)Ir HDR sources. The calibration coefficients of 35 well-type ionization chambers of two different chamber types for radiation fields of (60)Co and (192)Ir HDR brachytherapy sources were determined experimentally. A radiation quality correction factor kQ was determined as the ratio of the calibration coefficients for (60)Co and (192)Ir. The dependence on chamber-to-chamber variations, source-to-source variations, and source strength was investigated. For the PTW Tx33004 (Nucletron source dosimetry system (SDS)) well-type chamber, the type-specific radiation quality correction factor kQ is 1.19. Note that this value is valid for chambers with the serial number, SN ≥ 315 (Nucletron SDS SN ≥ 548) onward only. For the Standard Imaging HDR 1000 Plus well-type chambers, the type-specific correction factor kQ is 1.05. Both kQ values are independent of the source strengths in the complete clinically relevant range. The relative expanded uncertainty (k = 2) of kQ is UkQ = 2.1% for both chamber types. The calibration coefficient of a well-type chamber for radiation fields of (60)Co HDR brachytherapy sources can be calculated from a given calibration coefficient for (192)Ir radiation by using a chamber-type-specific radiation quality correction factor kQ. However, the uncertainty of a (60)Co calibration coefficient calculated via kQ is at least twice as large as that for a direct calibration with a (60)Co source.

  20. International policies to reduce plastic marine pollution from single-use plastics (plastic bags and microbeads): A review.

    PubMed

    Xanthos, Dirk; Walker, Tony R

    2017-05-15

    Marine plastic pollution has been a growing concern for decades. Single-use plastics (plastic bags and microbeads) are a significant source of this pollution. Although research outlining environmental, social, and economic impacts of marine plastic pollution is growing, few studies have examined policy and legislative tools to reduce plastic pollution, particularly single-use plastics (plastic bags and microbeads). This paper reviews current international market-based strategies and policies to reduce plastic bags and microbeads. While policies to reduce microbeads began in 2014, interventions for plastic bags began much earlier in 1991. However, few studies have documented or measured the effectiveness of these reduction strategies. Recommendations to further reduce single-use plastic marine pollution include: (i) research to evaluate effectiveness of bans and levies to ensure policies are having positive impacts on marine environments; and (ii) education and outreach to reduce consumption of plastic bags and microbeads at source. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Plastic debris in Mediterranean seabirds.

    PubMed

    Codina-García, Marina; Militão, Teresa; Moreno, Javier; González-Solís, Jacob

    2013-12-15

    Plastic debris is often ingested by marine predators and can cause health disorders and even death. We present the first assessment of plastic ingestion in Mediterranean seabirds. We quantified and measured plastics accumulated in the stomach of 171 birds from 9 species accidentally caught by longliners in the western Mediterranean from 2003 to 2010. Cory's shearwaters (Calonectris diomedea) showed the highest occurrence (94%) and large numbers of small plastic particles per affected bird (on average N = 15.3 ± 24.4 plastics and mass = 23.4 ± 49.6 mg), followed by Yelkouan shearwaters (Puffinus yelkouan, 70%, N = 7.0 ± 7.9, 42.1 ± 100.0 mg), Balearic shearwaters (Puffinus mauretanicus, 70%, N = 3.6 ± 2.9, 5.5 ± 9.7 mg) and the rest of species (below 33%, N = 2.7, 113.6 ± 128.4 mg). Plastic characteristics did not differ between sexes and were not related to the physical condition of the birds. Our results point out the three endemic and threatened shearwater species as being particularly exposed to plastic accumulation.

  2. Developmental plasticity: Friend or foe?

    PubMed

    Michels, Karin B

    2017-01-01

    Developmental plasticity - the concept that adaptation to changing and unfavorable environmental conditions are possible but may come at the price of compromised health potentials - has evolutionary grounding as it facilitates survival but dissents with fundamental evolutionary principles in that it may advance the lesser fit. It is an important cornerstone of the Developmental Origins of Health and Disease (DOHaD). Unlike evolutionary adaptation developmental plasticity may be short-lived and restricted to one or few generations and inheritance is uncertain. Potential mechanisms include epigenetic modifications adopted in utero which may not transmit to the next generation; future insights may allow adjustments of the outcomes of developmental plasticity.

  3. Recycling of Reinforced Plastics

    NASA Astrophysics Data System (ADS)

    Adams, R. D.; Collins, Andrew; Cooper, Duncan; Wingfield-Digby, Mark; Watts-Farmer, Archibald; Laurence, Anna; Patel, Kayur; Stevens, Mark; Watkins, Rhodri

    2014-02-01

    This work has shown is that it is possible to recycle continuous and short fibre reinforced thermosetting resins while keeping almost the whole of the original material, both fibres and matrix, within the recyclate. By splitting, crushing hot or cold, and hot forming, it is possible to create a recyclable material, which we designate a Remat, which can then be used to remanufacture other shapes, examples of plates and tubes being demonstrated. Not only can remanufacturing be done, but it has been shown that over 50 % of the original mechanical properties, such as the E modulus, tensile strength, and interlaminar shear strength, can be retained. Four different forms of composite were investigated, a random mat Glass Fibre Reinforced Plastic (GFRP) bathroom component and boat hull, woven glass and carbon fibre cloth impregnated with an epoxy resin, and unidirectional carbon fibre pre-preg. One of the main factors found to affect composite recyclability was the type of resin matrix used in the composite. Thermoset resins tested were shown to have a temperature range around the Glass Transition Temperature (Tg) where they exhibit ductile behaviour, hence aiding reforming of the material. The high-grade carbon fibre prepreg was found to be less easy to recycle than the woven of random fibre laminates. One method of remanufacturing was by heating the Remat to above its glass transition temperature, bending it to shape, and then cooling it. However, unless precautions are taken, the geometric form may revert. This does not happen with the crushed material.

  4. Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams.

    PubMed

    Lourenço, A; Wellock, N; Thomas, R; Homer, M; Bouchard, H; Kanai, T; MacDougall, N; Royle, G; Palmans, H

    2016-11-07

    Water-equivalent plastics are frequently used in dosimetry for experimental simplicity. This work evaluates the water-equivalence of novel water-equivalent plastics specifically designed for light-ion beams, as well as commercially available plastics in a clinical high-energy carbon-ion beam. A plastic- to-water conversion factor [Formula: see text] was established to derive absorbed dose to water in a water phantom from ionization chamber readings performed in a plastic phantom. Three trial plastic materials with varying atomic compositions were produced and experimentally characterized in a high-energy carbon-ion beam. Measurements were performed with a Roos ionization chamber, using a broad un-modulated beam of 11  ×  11 cm 2 , to measure the plastic-to-water conversion factor for the novel materials. The experimental results were compared with Monte Carlo simulations. Commercially available plastics were also simulated for comparison with the plastics tested experimentally, with particular attention to the influence of nuclear interaction cross sections. The measured [Formula: see text] correction increased gradually from 0% at the surface to 0.7% at a depth near the Bragg peak for one of the plastics prepared in this work, while for the other two plastics a maximum correction of 0.8%-1.3% was found. Average differences between experimental and numerical simulations were 0.2%. Monte Carlo results showed that for polyethylene, polystyrene, Rando phantom soft tissue and A-150, the correction increased from 0% to 2.5%-4.0% with depth, while for PMMA it increased to 2%. Water-equivalent plastics such as, Plastic Water, RMI-457, Gammex 457-CTG, WT1 and Virtual Water, gave similar results where maximum corrections were of the order of 2%. Considering the results from Monte Carlo simulations, one of the novel plastics was found to be superior in comparison with the plastic materials currently used in dosimetry, demonstrating that it is feasible to tailor

  5. Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams

    NASA Astrophysics Data System (ADS)

    Lourenço, A.; Wellock, N.; Thomas, R.; Homer, M.; Bouchard, H.; Kanai, T.; MacDougall, N.; Royle, G.; Palmans, H.

    2016-11-01

    Water-equivalent plastics are frequently used in dosimetry for experimental simplicity. This work evaluates the water-equivalence of novel water-equivalent plastics specifically designed for light-ion beams, as well as commercially available plastics in a clinical high-energy carbon-ion beam. A plastic- to-water conversion factor {{H}\\text{pl,w}} was established to derive absorbed dose to water in a water phantom from ionization chamber readings performed in a plastic phantom. Three trial plastic materials with varying atomic compositions were produced and experimentally characterized in a high-energy carbon-ion beam. Measurements were performed with a Roos ionization chamber, using a broad un-modulated beam of 11  ×  11 cm2, to measure the plastic-to-water conversion factor for the novel materials. The experimental results were compared with Monte Carlo simulations. Commercially available plastics were also simulated for comparison with the plastics tested experimentally, with particular attention to the influence of nuclear interaction cross sections. The measured H\\text{pl,w}\\exp correction increased gradually from 0% at the surface to 0.7% at a depth near the Bragg peak for one of the plastics prepared in this work, while for the other two plastics a maximum correction of 0.8%-1.3% was found. Average differences between experimental and numerical simulations were 0.2%. Monte Carlo results showed that for polyethylene, polystyrene, Rando phantom soft tissue and A-150, the correction increased from 0% to 2.5%-4.0% with depth, while for PMMA it increased to 2%. Water-equivalent plastics such as, Plastic Water, RMI-457, Gammex 457-CTG, WT1 and Virtual Water, gave similar results where maximum corrections were of the order of 2%. Considering the results from Monte Carlo simulations, one of the novel plastics was found to be superior in comparison with the plastic materials currently used in dosimetry, demonstrating that it is feasible to tailor plastic

  6. Ag/SiO2 surface-enhanced Raman scattering substrate for plasticizer detection

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chung; Lin, Ming-Pin; Lin, Ting-Han; Su, Wei-Fang

    2018-04-01

    In this study, we demonstrated a simple method of fabricating a high-performance surface-enhanced Raman scattering (SERS) substrate. Monodispersive SiO2 colloidal spheres were self-assembled on a silicon wafer, and then a silver layer was coated on it to obtain a Ag/SiO2 SERS substrate. The Ag/SiO2 SERS substrates were used to detect three kinds of plasticizer with different concentrations, namely, including bis(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate (BBP), and dibutyl phthalate (DBP). The enhancement of Raman scattering intensity caused by surface plasmon resonance can be observed using the Ag/SiO2 SERS substrates. The Ag/SiO2 SERS substrate with a 150-nm-thick silver layer can detect plasticizers, and it satisfies the detection limit of plasticizers at 100 ppm. The developed highly sensitive Ag/SiO2 SERS substrates show a potential for the design and fabrication of functional sensors to identify the harmful plasticizers that plastic products release in daily life.

  7. Neuromodulation, development and synaptic plasticity.

    PubMed

    Foehring, R C; Lorenzon, N M

    1999-03-01

    We discuss parallels in the mechanisms underlying use-dependent synaptic plasticity during development and long-term potentiation (LTP) and long-term depression (LTD) in neocortical synapses. Neuromodulators, such as norepinephrine, serotonin, and acetylcholine have also been implicated in regulating both developmental plasticity and LTP/LTD. There are many potential levels of interaction between neuromodulators and plasticity. Ion channels are substrates for modulation in many cell types. We discuss examples of modulation of voltage-gated Ca2+ channels and Ca(2+)-dependent K+ channels and the consequences for neocortical pyramidal cell firing behaviour. At the time when developmental plasticity is most evident in rat cortex, the substrate for modulation is changing as the densities and relative proportions of various ion channels types are altered during ontogeny. We discuss examples of changes in K+ and Ca2+ channels and the consequence for modulation of neuronal activity.

  8. Remote Sensing of Plastic Debris

    NASA Astrophysics Data System (ADS)

    Garaba, S. P.; Dierssen, H. M.

    2016-02-01

    Plastic debris is becoming a nuisance in the environment and as a result there has been a dire need to synoptically detect and quantify them in the ocean and on land. We investigate the possible utility of spectral information determined from hand held, airborne and satellite remote sensing tools in the detection and identification polymer source of plastic debris. Sampled debris will be compared to our derived spectral library of typical raw polymer sources found at sea and in household waste. Additional work will be to determine ways to estimate the abundance of plastic debris in target areas. Implications of successful remote detection, tracking and quantification of plastic debris will be towards validating field observations over large areas and at repeated time intervals both on land and at sea.

  9. Plastics (Environmental Health Student Portal)

    MedlinePlus

    ... and flexible, and the risks they present to human health. Super Mallio Brothers (National Library of Medicine) - This ... the production of plastics for the environment and human health. World of Plasticraft (National Library of Medicine) - Journey ...

  10. THERMAL DEPOLYMERIZATION OF POSTCONSUMER PLASTICS

    EPA Science Inventory

    The University of North Dakota Energy & Environmental Research Center (EERC) performed two series of tests to evaluate process conditions for thermal depolymerization of postconsumer plastics. The objective of the first test series was to provide data for optimization of reactio...

  11. WEATHERABILITY OF ENHANCED DEGRADABLE PLASTICS

    EPA Science Inventory

    The main objective of this study was to assess the performance and the asociated variability of several selected enhanced degradable plastic materials under a variety of different exposure conditions. Other objectives were to identify the major products formed during degradation ...

  12. Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

    SciTech Connect

    Anderson, D; McEwen, M; Shen, H

    Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC wasmore » benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (∼8 – 100 keV) and 05ID-2 (∼20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ∼ 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors.« less

  13. Nano-Ceramic Coated Plastics

    NASA Technical Reports Server (NTRS)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (<100 C) is also a key to generating these ceramic coatings on the plastics. One possible way of processing nanoceramic coatings at low temperatures (< 90 C) is to take advantage of in-situ precipitated nanoparticles and nanostructures grown from aqueous solution. These nanostructures can be tailored to ceramic film formation and the subsequent microstructure development. In addition, the process provides environment- friendly processing because of the

  14. Interhemispheric plasticity in humans.

    PubMed

    Hortobágyi, Tibor; Richardson, Sarah Pirio; Lomarev, Mikhael; Shamim, Ejaz; Meunier, Sabine; Russman, Heike; Dang, Nguyet; Hallett, Mark

    2011-07-01

    Chronic unimanual motor practice increases the motor output not only in the trained but also in the nonexercised homologous muscle in the opposite limb. We examined the hypothesis that adaptations in motor cortical excitability of the nontrained primary motor cortex (iM1) and in interhemispheric inhibition from the trained to the nontrained M1 mediate this interlimb cross education. Healthy, young volunteers (n=12) performed 1000 submaximal voluntary contractions (MVC) of the right first dorsal interosseus (FDI) at 80% MVC during 20 sessions. Trained FDI's MVC increased 49.9%, and the untrained FDI's MVC increased 28.1%. Although corticospinal excitability in iM1, measured with transcranial magnetic stimulation (TMS) before and after every fifth session, increased 6% at rest, these changes, as those in intracortical inhibition and facilitation, did not correlate with cross education. When weak and strong TMS of iM1 were delivered on a background of a weak and strong muscle contraction, respectively, of the right FDI, excitability of iM1 increased dramatically after 20 sessions. Interhemispheric inhibition decreased 8.9% acutely within sessions and 30.9% chronically during 20 sessions and these chronic reductions progressively became more strongly associated with cross education. There were no changes in force or TMS measures in the trained group's left abductor minimi digiti and there were no changes in the nonexercising control group (n=8). The findings provide the first evidence for plasticity of interhemispheric connections to mediate cross education produced by a simple motor task.

  15. Bioterrorism: Preparing the Plastic Surgeon

    PubMed Central

    Chopra, Karan; Conde-Green, Alexandra; Folstein, Matthew K.; Knepp, Erin K.; Christy, Michael R.; Singh, Devinder P.

    2011-01-01

    Introduction: Many medical disciplines, such as emergency medicine, trauma surgery, dermatology, psychiatry, family practice, and dentistry have documented attempts at assessing the level of bioterrorism preparedness in their communities. Currently, there is neither such an assessment nor an existing review of potential bioterrorism agents as they relate to plastic surgery. Therefore, the purpose of this article is to present plastic surgeons with a review of potential bioterrorism agents. Methods: A review of the literature on bioterrorism agents and online resources of the Centers for Disease Control and Prevention was conducted. Category A agents were identified and specific attention was paid to the management issues that plastic surgeons might face in the event that these agents are used in an attack. Results: Disease entities reviewed were smallpox, anthrax, plague, viral hemorrhagic fever, tularemia, and botulism. For each agent, we presented the microbiology, pathophysiology, clinical presentation, potential for weaponization, medical management, and surgical issues related to the plastic surgeon. Conclusion: This article is the first attempt at addressing preparedness for bioterrorism in the plastic surgery community. Many other fields have already started a similar process. This article represents a first step in developing evidence-based consensus guidelines and recommendations for the management of biological terrorism for plastic surgeons. PMID:22132252

  16. 49 CFR 192.59 - Plastic pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Plastic pipe. 192.59 Section 192.59 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.59 Plastic pipe. (a) New plastic pipe... specification; and (2) It is resistant to chemicals with which contact may be anticipated. (b) Used plastic pipe...

  17. The Story of the Plastics Industry.

    ERIC Educational Resources Information Center

    Masson, Don, Ed.

    This is an illustrated informative booklet, designed to serve members of the Society of the Plastics Industry, Inc., and the plastics industry as a whole. It provides basic information about the industry's history and growth, plastics raw materials, typical uses of plastics, properties, and methods of processing and fabricating. (Author/DS)

  18. 49 CFR 192.59 - Plastic pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Plastic pipe. 192.59 Section 192.59 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.59 Plastic pipe. (a) New plastic pipe... specification; and (2) It is resistant to chemicals with which contact may be anticipated. (b) Used plastic pipe...

  19. 49 CFR 192.59 - Plastic pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Plastic pipe. 192.59 Section 192.59 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.59 Plastic pipe. (a) New plastic pipe... specification; and (2) It is resistant to chemicals with which contact may be anticipated. (b) Used plastic pipe...

  20. 49 CFR 192.59 - Plastic pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Plastic pipe. 192.59 Section 192.59 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.59 Plastic pipe. (a) New plastic pipe... specification; and (2) It is resistant to chemicals with which contact may be anticipated. (b) Used plastic pipe...

  1. Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

    NASA Astrophysics Data System (ADS)

    Wise, K. N.; Sandborg, M.; Persliden, J.; Alm Carlsson, G.

    1999-08-01

    We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient (varepsilon) to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of varepsilon/KAP by a factor of 1.3 and of varepsilon/ESD by up to a factor of 2. While KAP is preferred to determine varepsilon, the results show no strong preference of KAP over ESD in determining E. The mean absorbed dose (barD) in the patient obtained by dividing

  2. Integral neutron kerma coefficient ratios for silicon, iron, and oxygen to carbon on the energy range from 15 to 30 MeV

    NASA Astrophysics Data System (ADS)

    Miranda, Juan Gustavo

    2001-07-01

    Kerma coefficient ratios are reported for carbon to oxygen, silicon, and iron in the energy range of 15 to 30 MeV. The determination was done by measuring dose to the gas of proportional counters exposed to a well characterized neutron field. The measured dose in the proportional counter gas was then converted to dose in the proportional counter wall material applying Bragg-Gray theory. The proportional counters were made of the material of interest. The oxygen measurement was done by irradiating simultaneously zirconium and zirconium oxide proportional counters and substracting the dose to the zirconium from the zirconium oxide. Neutrons were generated with the UW Tandem Accelerator. The reaction 3H(d, n)4 He provided our neutron source which consisted of monoenergetic neutrons. Neutron spectra measurements were carried out for the 27.3 MeV neutron energy. This was necessary because of the presence of contaminating breakup neutrons at this energy. The spectra were measured with a pulse beam time-of-flight spectrometer and a NE-213 liquid scintillator. The dose conversion factor r is reported for carbon, oxygen, silicon, iron, zirconium, and zirconium oxide relative to TE-propane gas at neutron energies of 20, 23 and 27 MeV. The factor r, which relates the dose to the gas to that of the proportional counter through the Bragg-Gray theory, was calculated from angle integrated differential cross sections. This required a calculation of the initial energy spectra as well as the differential secondary charged particle energy spectra and for the first time a complete treatment of all heavy ions is considered. Furthermore, as the conditions required to apply the Bragg-Gray theory are difficult to satisfy (infinitesimal cavity), we report the calculation of the dose conversion factor r for the finite cavity case for carbon/TE-gas in order to test the validity of the application of the theory to this type of applications. We found that the two conditions of the Bragg

  3. Water Vapor Permeation in Plastics

    SciTech Connect

    Keller, Paul E.; Kouzes, Richard T.

    Polyvinyl toluene (PVT) and polystyrene (PS) (referred to as “plastic scintillator”) are used for gamma ray detectors. A significant decrease in radiation detection performance has been observed in some PVT-based gamma-ray detectors in systems in outdoor environments as they age. Recent studies have revealed that plastic scintillator can undergo an environmentally related material degradation that adversely affects gamma ray detection performance under certain conditions and histories. A significant decrease in sensitivity has been seen in some gamma-ray detectors in some systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors,more » and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. The objective of this report is to document the phenomenon of permeability of plastic scintillator to water vapor and to derive the relationship between time, temperature, humidity and degree of water penetration in plastic. Several conclusions are documented about the properties of water permeability of plastic scintillator.« less

  4. Brightness and uniformity measurements of plastic scintillator tiles at the CERN H2 test beam

    DOE PAGES

    Chatrchyan, S.; Sirunyan, A. M.; Tumasyan, A.; ...

    2018-01-05

    Here, we study the light output, light collection efficiency and signal timing of a variety of organic scintillators that are being considered for the upgrade of the hadronic calorimeter of the CMS detector. The experimental data are collected at the H2 test-beam area at CERN, using a 150 GeV muon beam. In particular, we investigate the usage of over-doped and green-emitting plastic scintillators, two solutions that have not been extensively considered. We present a study of the energy distribution in plastic-scintillator tiles, the hit efficiency as a function of the hit position, and a study of the signal timing formore » blue and green scintillators.« less

  5. Brightness and uniformity measurements of plastic scintillator tiles at the CERN H2 test beam

    SciTech Connect

    Chatrchyan, S.; Sirunyan, A. M.; Tumasyan, A.

    Here, we study the light output, light collection efficiency and signal timing of a variety of organic scintillators that are being considered for the upgrade of the hadronic calorimeter of the CMS detector. The experimental data are collected at the H2 test-beam area at CERN, using a 150 GeV muon beam. In particular, we investigate the usage of over-doped and green-emitting plastic scintillators, two solutions that have not been extensively considered. We present a study of the energy distribution in plastic-scintillator tiles, the hit efficiency as a function of the hit position, and a study of the signal timing formore » blue and green scintillators.« less

  6. Brightness and uniformity measurements of plastic scintillator tiles at the CERN H2 test beam

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Sirunyan, A. M.; Tumasyan, A.; Litomin, A.; Mossolov, V.; Shumeiko, N.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Spilbeeck, A.; Alves, G. A.; Aldá Júnior, W. L.; Hensel, C.; Carvalho, W.; Chinellato, J.; De Oliveira Martins, C.; Matos Figueiredo, D.; Mora Herrera, C.; Nogima, H.; Prado Da Silva, W. L.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Finger, M.; Finger, M., Jr.; Kveton, A.; Tomsa, J.; Adamov, G.; Tsamalaidze, Z.; Behrens, U.; Borras, K.; Campbell, A.; Costanza, F.; Gunnellini, P.; Lobanov, A.; Melzer-Pellmann, I.-A.; Muhl, C.; Roland, B.; Sahin, M.; Saxena, P.; Hegde, V.; Kothekar, K.; Pandey, S.; Sharma, S.; Beri, S. B.; Bhawandeep, B.; Chawla, R.; Kalsi, A.; Kaur, A.; Kaur, M.; Walia, G.; Bhattacharya, S.; Ghosh, S.; Nandan, S.; Purohit, A.; Sharan, M.; Banerjee, S.; Bhattacharya, S.; Chatterjee, S.; Das, P.; Guchait, M.; Jain, S.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Patil, M.; Sarkar, T.; Juodagalvis, A.; Afanasiev, S.; Bunin, P.; Ershov, Y.; Golutvin, I.; Malakhov, A.; Moisenz, P.; Smirnov, V.; Zarubin, A.; Chadeeva, M.; Chistov, R.; Danilov, M.; Popova, E.; Rusinov, V.; Andreev, Yu.; Dermenev, A.; Karneyeu, A.; Krasnikov, N.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Toms, M.; Zhokin, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Kaminskiy, A.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Terkulov, A.; Bitioukov, S.; Elumakhov, D.; Kalinin, A.; Krychkine, V.; Mandrik, P.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Volkov, A.; Sekmen, S.; Medvedeva, T.; Rumerio, P.; Adiguzel, A.; Bakirci, N.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dölek, F.; Dozen, C.; Dumanoglu, I.; Eskut, E.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kayis Topaksu, A.; Işik, C.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Ozturk, S.; Polatoz, A.; Sunar Cerci, D.; Tali, B.; Tok, U. G.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Isildak, B.; Karapinar, G.; Murat Guler, A.; Ocalan, K.; Yalvac, M.; Zeyrek, M.; Atakisi, I. O.; Gülmez, E.; Kaya, M.; Kaya, O.; Koseyan, O. K.; Ozcelik, O.; Ozkorucuklu, S.; Tekten, S.; Yetkin, E. A.; Yetkin, T.; Cankocak, K.; Sen, S.; Boyarintsev, A.; Grynyov, B.; Levchuk, L.; Popov, V.; Sorokin, P.; Flacher, H.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Buccilli, A.; Cooper, S. I.; Henderson, C.; West, C.; Arcaro, D.; Gastler, D.; Hazen, E.; Rohlf, J.; Sulak, L.; Wu, S.; Zou, D.; Hakala, J.; Heintz, U.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Yu, D. R.; Gary, J. W.; Ghiasi Shirazi, S. M.; Lacroix, F.; Long, O. R.; Wei, H.; Bhandari, R.; Heller, R.; Stuart, D.; Yoo, J. H.; Chen, Y.; Duarte, J.; Lawhorn, J. M.; Nguyen, T.; Spiropulu, M.; Winn, D.; Abdullin, S.; Apresyan, A.; Apyan, A.; Banerjee, S.; Chlebana, F.; Freeman, J.; Green, D.; Hare, D.; Hirschauer, J.; Joshi, U.; Lincoln, D.; Los, S.; Pedro, K.; Spalding, W. J.; Strobbe, N.; Tkaczyk, S.; Whitbeck, A.; Linn, S.; Markowitz, P.; Martinez, G.; Bertoldi, M.; Hagopian, S.; Hagopian, V.; Kolberg, T.; Baarmand, M. M.; Noonan, D.; Roy, T.; Yumiceva, F.; Bilki, B.; Clarida, W.; Debbins, P.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Miller, M.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Schmidt, I.; Snyder, C.; Southwick, D.; Tiras, E.; Yi, K.; Al-bataineh, A.; Bowen, J.; Castle, J.; McBrayer, W.; Murray, M.; Wang, Q.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Baden, A.; Belloni, A.; Calderon, J. D.; Eno, S. C.; Feng, Y. B.; Ferraioli, C.; Grassi, T.; Hadley, N. J.; Jeng, G.-Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Yang, Z. S.; Yao, Y.; Brandt, S.; D'Alfonso, M.; Hu, M.; Klute, M.; Niu, X.; Chatterjee, R. M.; Evans, A.; Frahm, E.; Kubota, Y.; Lesko, Z.; Mans, J.; Ruckstuhl, N.; Heering, A.; Karmgard, D. J.; Musienko, Y.; Ruchti, R.; Wayne, M.; Benaglia, A. D.; Mei, K.; Tully, C.; Bodek, A.; de Barbaro, P.; Galanti, M.; Garcia-Bellido, A.; Khukhunaishvili, A.; Lo, K. H.; Vishnevskiy, D.; Zielinski, M.; Agapitos, A.; Amouzegar, M.; Chou, J. P.; Hughes, E.; Saka, H.; Sheffield, D.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Mengke, T.; Muthumuni, S.; Undleeb, S.; Volobouev, I.; Wang, Z.; Goadhouse, S.; Hirosky, R.; Wang, Y.

    2018-01-01

    We study the light output, light collection efficiency and signal timing of a variety of organic scintillators that are being considered for the upgrade of the hadronic calorimeter of the CMS detector. The experimental data are collected at the H2 test-beam area at CERN, using a 150 GeV muon beam. In particular, we investigate the usage of over-doped and green-emitting plastic scintillators, two solutions that have not been extensively considered. We present a study of the energy distribution in plastic-scintillator tiles, the hit efficiency as a function of the hit position, and a study of the signal timing for blue and green scintillators.

  7. Avalanches and plastic flow in crystal plasticity: an overview

    NASA Astrophysics Data System (ADS)

    Papanikolaou, Stefanos; Cui, Yinan; Ghoniem, Nasr

    2018-01-01

    Crystal plasticity is mediated through dislocations, which form knotted configurations in a complex energy landscape. Once they disentangle and move, they may also be impeded by permanent obstacles with finite energy barriers or frustrating long-range interactions. The outcome of such complexity is the emergence of dislocation avalanches as the basic mechanism of plastic flow in solids at the nanoscale. While the deformation behavior of bulk materials appears smooth, a predictive model should clearly be based upon the character of these dislocation avalanches and their associated strain bursts. We provide here a comprehensive overview of experimental observations, theoretical models and computational approaches that have been developed to unravel the multiple aspects of dislocation avalanche physics and the phenomena leading to strain bursts in crystal plasticity.

  8. Smartphones and the plastic surgeon.

    PubMed

    Al-Hadithy, Nada; Ghosh, Sudip

    2013-06-01

    Surgical trainees are facing limited training opportunities since the introduction of the European Working Time Directive. Smartphone sales are increasing and have usurped computer sales for the first time. In this context, smartphones are an important portable reference and educational tool, already in the possession of the majority of surgeons in training. Technology in the palm of our hands has led to a revolution of accessible information for the plastic surgery trainee and surgeon. This article reviews the uses of smartphones and applications for plastic surgeons in education, telemedicine and global health. A comprehensive guide to existing and upcoming learning materials and clinical tools for the plastic surgeon is included. E-books, podcasts, educational videos, guidelines, work-based assessment tools and online logbooks are presented. In the limited resource setting of modern clinical practice, savvy plastic surgeons can select technological tools to democratise access to education and best clinical care. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  9. Deciphering indented impressions on plastic.

    PubMed

    Brown, Sharon; Klein, Asne; Chaikovsky, Alan

    2003-07-01

    The questioned document laboratory is often called upon to decipher writing that has been erased, obliterated, or that has faded. In cases like these, the original writing is no longer legible to the naked eye, but may be enhanced using various light sources. Certain remnants of the ink's components absorb into the substrate's fibers and can be visualized, usually as luminescence or absorbance. A case is described here that involved the theft of a credit card. An empty plastic credit card holder was found in the possession of a suspect, and as submitted for examination. Indented impressions could be discerned on its clear plastic window and presumably originated from the credit card that had been held in the envelope. These indented impressions were deciphered in the hope that they would reveal enough details from the credit card to establish a connection between the plastic envelope and the stolen credit card. With methods generally utilized in the toolmarks and materials laboratory and the photography laboratory of the Israel Police, most of the indented impressions on the plastic were deciphered and a connection between the plastic envelope and the stolen credit card was demonstrated.

  10. Integrated analyses in plastics forming

    NASA Astrophysics Data System (ADS)

    Bo, Wang

    This is the thesis which explains the progress made in the analysis, simulation and testing of plastics forming. This progress can be applied to injection and compression mould design. Three activities of plastics forming have been investigated, namely filling analysis, cooling analysis and ejecting analysis. The filling section of plastics forming has been analysed and calculated by using MOLDFLOW and FILLCALC V. software. A comparing of high speed compression moulding and injection moulding has been made. The cooling section of plastics forming has been analysed by using MOLDFLOW software and a finite difference computer program. The latter program can be used as a sample program to calculate the feasibility of cooling different materials to required target temperatures under controlled cooling conditions. The application of thermal imaging has been also introduced to determine the actual process temperatures. Thermal imaging can be used as a powerful tool to analyse mould surface temperatures and to verify the mathematical model. A buckling problem for ejecting section has been modelled and calculated by PATRAN/ABAQUS finite element analysis software and tested. These calculations and analysis are applied to the special case but can be use as an example for general analysis and calculation in the ejection section of plastics forming.

  11. Plasticity in Glutamatergic NTS Neurotransmission

    PubMed Central

    Kline, David D.

    2008-01-01

    Changes in the physiological state of an animal or human can result in alterations in the cardiovascular and respiratory system in order to maintain homeostasis. Accordingly, the cardiovascular and respiratory systems are not static but readily adapt under a variety of circumstances. The same can be said for the brainstem circuits that control these systems. The nucleus tractus solitarius (NTS) is the central integration site of baroreceptor and chemoreceptor sensory afferent fibers. This central nucleus, and in particular the synapse between the sensory afferent and second-order NTS cell, possesses a remarkable degree of plasticity in response to a variety of stimuli, both acute and chronic. This brief review is intended to describe the plasticity observed in the NTS as well as the locus and mechanisms as they are currently understood. The functional consequence of NTS plasticity is also discussed. PMID:18524694

  12. Excitation Spectra in Crystal Plasticity

    NASA Astrophysics Data System (ADS)

    Ovaska, Markus; Lehtinen, Arttu; Alava, Mikko J.; Laurson, Lasse; Zapperi, Stefano

    2017-12-01

    Plastically deforming crystals exhibit scale-free fluctuations that are similar to those observed in driven disordered elastic systems close to depinning, but the nature of the yielding critical point is still debated. Here, we study the marginal stability of ensembles of dislocations and compute their excitation spectrum in two and three dimensions. Our results show the presence of a singularity in the distribution of excitation stresses, i.e., the stress needed to make a localized region unstable, that is remarkably similar to the one measured in amorphous plasticity and spin glasses. These results allow us to understand recent observations of extended criticality in bursty crystal plasticity and explain how they originate from the presence of a pseudogap in the excitation spectrum.

  13. Oxytocin and Maternal Brain Plasticity.

    PubMed

    Kim, Sohye; Strathearn, Lane

    2016-09-01

    Although dramatic postnatal changes in maternal behavior have long been noted, we are only now beginning to understand the neurobiological mechanisms that support this transition. The present paper synthesizes growing insights from both animal and human research to provide an overview of the plasticity of the mother's brain, with a particular emphasis on the oxytocin system. We examine plasticity observed within the oxytocin system and discuss how these changes mediate an array of other adaptations observed within the maternal brain. We outline factors that affect the oxytocin-mediated plasticity of the maternal brain and review evidence linking disruptions in oxytocin functions to challenges in maternal adaptation. We conclude by suggesting a strategy for intervention with mothers who may be at risk for maladjustment during this transition to motherhood, while highlighting areas where further research is needed. © 2016 Wiley Periodicals, Inc.

  14. Surface properties of beached plastics.

    PubMed

    Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

    2015-07-01

    Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

  15. Extruded plastic scintillator including inorganic powders

    DOEpatents

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-06-27

    A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

  16. High energy resolution plastic scintillator

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Feng, Patrick; Markosyan, Gary; Shirwadkar, Urmila; Doty, Patrick; Shah, Kanai S.

    2016-09-01

    In this paper we present results on a novel tin-loaded plastic scintillator. We will show that this particular plastic scintillator has a light output similar to that of BGO, a fast scintillation decay (< 10 ns), exhibits good neutron/gamma PSD with a Figure-of-Merit of 1.3 at 2.5 MeVee cut-off energy, and excellent energy resolution of about 12% (FWHM) at 662 keV. Under X-ray excitation, the radioluminescence spectrum exhibits a broad band between 350 and 500 nm peaking at 420 nm which is well-matched to bialkali photomultiplier tubes and UV-enhanced photodiodes.

  17. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, Michael S.

    1995-01-01

    A polishing compound for plastic surfaces. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS.TM., LEXAN.TM., LUCITE.TM., polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  18. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1993-01-01

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains colloidal silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{sup TM}, LEXAN{sup TM}, LUCITE{sup TM}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  19. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1995-08-22

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired. 5 figs.

  20. For the Classroom: "Plastic" Jellyfish.

    ERIC Educational Resources Information Center

    Current: The Journal of Marine Education, 1989

    1989-01-01

    Describes an activity in which students monitor the plastic waste production in their households, research its effects on freshwater and marine life, and propose ways to lessen the problem. Provides objectives, background information, materials, procedures, extension activities, and an evaluation for students. (Author/RT)

  1. Burnout among plastic surgery residents

    PubMed Central

    Aldrees, Turki; Hassouneh, Basil; Alabdulkarim, Abdulaziz; Asad, Loujin; Alqaryan, Saleh; Aljohani, Emad; Alqahtani, Khalid

    2017-01-01

    Objectives: To develop a more comprehensive explanation and understanding of the prevalence of and factors associated with burnout for residents of the Saudi Plastic Surgery Residency Program. Methods: This is a cross sectional study. Data was gathered using a survey, which was distributed during April 2015, among all 57 plastic surgery residents enrolled in training programs across all regions of Saudi Arabia, 38 of whom responded (60% response rate). The dependent variable was professional burnout, which was measured by 3 subscales of the validated Maslach Burnout Inventory (MBI). High scores on emotional exhaustion (EE) or depersonalization (DP) or low scores on personal accomplishment (PA) were taken to be indicative of professional burnout. Variables evaluating possible predictors of burnout, such as sociodemographic and professional characteristics, were also included. Results: The validated rate of high burnout status was 18%. Nearly three quarters (71%) of residents scored high in emotional exhaustion, and half (50%) scored high in depersonalization. A third (34%) scored low in personal accomplishment. However, only 5% were dissatisfied with the plastic surgery specialty as a career, and 69% would choose the same specialty again. Workload was not found to play a significant role in the development of burnout (mean 70 hours per week). Conclusion: Approximately half of plastic surgery trainees in the Kingdom of Saudi Arabia have signs of professional burnout. PMID:28762436

  2. Ways of Viewing Pictorial Plasticity

    PubMed Central

    2017-01-01

    The plastic effect is historically used to denote various forms of stereopsis. The vivid impression of depth often associated with binocular stereopsis can also be achieved in other ways, for example, using a synopter. Accounts of this go back over a hundred years. These ways of viewing all aim to diminish sensorial evidence that the picture is physically flat. Although various viewing modes have been proposed in the literature, their effects have never been compared. In the current study, we compared three viewing modes: monocular blur, synoptic viewing, and free viewing (using a placebo synopter). By designing a physical embodiment that was indistinguishable for the three experimental conditions, we kept observers naïve with respect to the differences between them; 197 observers participated in an experiment where the three viewing modes were compared by performing a rating task. Results indicate that synoptic viewing causes the largest plastic effect. Monocular blur scores lower than synoptic viewing but is still rated significantly higher than the baseline conditions. The results strengthen the idea that synoptic viewing is not due to a placebo effect. Furthermore, monocular blur has been verified for the first time as a way of experiencing the plastic effect, although the effect is smaller than synoptic viewing. We discuss the results with respect to the theoretical basis for the plastic effect. We show that current theories are not described with sufficient details to explain the differences we found. PMID:28491270

  3. Field based plastic contamination sensing

    USDA-ARS?s Scientific Manuscript database

    The United States has a long-held reputation of being a dependable source of high quality, contaminant-free cotton. Recently, increased incidence of plastic contamination from sources such as shopping bags, vegetable mulch, surface irrigation tubing, and module covers has threatened the reputation o...

  4. Gene therapy in plastic surgery.

    PubMed

    Tepper, Oren M; Mehrara, Babak J

    2002-02-01

    Recent developments in gene therapy have shown promise in the treatment of soft-tissue repair, bone formation, nerve regeneration, and cranial suture development. This special topic article reviews commonly used methods of gene therapy and discusses their various advantages and disadvantages. In addition, an overview of new developments in gene therapy as they relate to plastic surgery is provided.

  5. Body dysmorphia and plastic surgery.

    PubMed

    Kyle, Allison

    2012-01-01

    Body dysmorphic disorder is a mental disorder characterized by a preoccupation with some aspect of one's appearance. In cosmetic surgery, this preoccupation can be overlooked by practitioners resulting in a discrepancy between expected and realistic outcome. Identifying the characteristics of this disorder may be crucial to the practitioner-patient relationship in the plastic surgery setting.

  6. Plastic Clamp Retains Clevis Pin

    NASA Technical Reports Server (NTRS)

    Cortes, R. G.

    1983-01-01

    Plastic clamp requires no special installation or removal tools. Clamp slips easily over end of pin. Once engaged in groove, holds pin securely. Installed and removed easily without special tools - screwdriver or putty knife adequate for prying out of groove. Used to retain bearings, rollers pulleys, other parts that rotate. Applications include slowly and intermittently rotating parts in appliances.

  7. Oxytocin and Maternal Brain Plasticity

    ERIC Educational Resources Information Center

    Kim, Sohye; Strathearn, Lane

    2016-01-01

    Although dramatic postnatal changes in maternal behavior have long been noted, we are only now beginning to understand the neurobiological mechanisms that support this transition. The present paper synthesizes growing insights from both animal and human research to provide an overview of the plasticity of the mother's brain, with a particular…

  8. Synaptic Plasticity and Translation Initiation

    ERIC Educational Resources Information Center

    Klann, Eric; Antion, Marcia D.; Banko, Jessica L.; Hou, Lingfei

    2004-01-01

    It is widely accepted that protein synthesis, including local protein synthesis at synapses, is required for several forms of synaptic plasticity. Local protein synthesis enables synapses to control synaptic strength independent of the cell body via rapid protein production from pre-existing mRNA. Therefore, regulation of translation initiation is…

  9. [The history of plastic surgery in Israel].

    PubMed

    Wiser, Itay; Scheflan, Michael; Heller, Lior

    2014-09-01

    The medical institutions in the country have advanced together with the development of the state of Israel. Plastic surgery, which has progressed significantly during the 20th century, has also grown rapidly in the new state. The arrival of Jewish plastic surgeons from all over the world with the knowledge and experience gained in their countries of origin, as well as the need for reconstructive surgical treatment for many combat injured soldiers, also contributed to the development of plastic surgery. This review tells the story of plastic surgery in Israel, since its foundation until nowadays. This article reviews the work of the founders of plastic surgery in Israel, indicating significant milestones in its development, and clinical and scientific contribution to the international plastic surgery profession. Moreover, the article describes the current condition of the field of plastic surgery in Israel and presents the trends and the future challenges facing the next generation of plastic surgery in Israel.

  10. Chemistry technology: Adhesives and plastics: A compilation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Technical information on chemical formulations for improving and/or producing adhesives is presented. Data are also reported on polymeric plastics with special characteristics or those plastics that were produced by innovative means.

  11. Interpretation on Recycling Plastics from Shredder Residue

    EPA Pesticide Factsheets

    EPA is considering an interpretation of its regulations that would generally allow for recycling of plastic separated from shredder residue under the conditions described in the Voluntary Procedures for Recycling Plastics from Shredder Residue.

  12. Plastics and beaches: a degrading relationship.

    PubMed

    Corcoran, Patricia L; Biesinger, Mark C; Grifi, Meriem

    2009-01-01

    Plastic debris in Earth's oceans presents a serious environmental issue because breakdown by chemical weathering and mechanical erosion is minimal at sea. Following deposition on beaches, plastic materials are exposed to UV radiation and physical processes controlled by wind, current, wave and tide action. Plastic particles from Kauai's beaches were sampled to determine relationships between composition, surface textures, and plastics degradation. SEM images indicated that beach plastics feature both mechanically eroded and chemically weathered surface textures. Granular oxidation textures were concentrated along mechanically weakened fractures and along the margins of the more rounded plastic particles. Particles with oxidation textures also produced the most intense peaks in the lower wavenumber region of FTIR spectra. The textural results suggest that plastic debris is particularly conducive to both chemical and mechanical breakdown in beach environments, which cannot be said for plastics in other natural settings on Earth.

  13. SU-E-T-552: Monte Carlo Calculation of Correction Factors for a Free-Air Ionization Chamber in Support of a National Air-Kerma Standard for Electronic Brachytherapy

    SciTech Connect

    Mille, M; Bergstrom, P

    2015-06-15

    Purpose: To use Monte Carlo radiation transport methods to calculate correction factors for a free-air ionization chamber in support of a national air-kerma standard for low-energy, miniature x-ray sources used for electronic brachytherapy (eBx). Methods: The NIST is establishing a calibration service for well-type ionization chambers used to characterize the strength of eBx sources prior to clinical use. The calibration approach involves establishing the well-chamber’s response to an eBx source whose air-kerma rate at a 50 cm distance is determined through a primary measurement performed using the Lamperti free-air ionization chamber. However, the free-air chamber measurements of charge or currentmore » can only be related to the reference air-kerma standard after applying several corrections, some of which are best determined via Monte Carlo simulation. To this end, a detailed geometric model of the Lamperti chamber was developed in the EGSnrc code based on the engineering drawings of the instrument. The egs-fac user code in EGSnrc was then used to calculate energy-dependent correction factors which account for missing or undesired ionization arising from effects such as: (1) attenuation and scatter of the x-rays in air; (2) primary electrons escaping the charge collection region; (3) lack of charged particle equilibrium; (4) atomic fluorescence and bremsstrahlung radiation. Results: Energy-dependent correction factors were calculated assuming a monoenergetic point source with the photon energy ranging from 2 keV to 60 keV in 2 keV increments. Sufficient photon histories were simulated so that the Monte Carlo statistical uncertainty of the correction factors was less than 0.01%. The correction factors for a specific eBx source will be determined by integrating these tabulated results over its measured x-ray spectrum. Conclusion: The correction factors calculated in this work are important for establishing a national standard for eBx which will help ensure

  14. 7 CFR 58.326 - Plastic cream.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

  15. Plastics. A Handbook for Workplace Educators.

    ERIC Educational Resources Information Center

    Curry, Donna; Smith, Mikki

    This handbook was designed to help adult literacy education teachers to understand the plastics industry, develop a curriculum, and teach basic skills classes in a plastics company. The book contains four main sections. The first section, on the basics of plastics, contains a brief history of the industry, an elementary description of the…

  16. The Rhetorical Limits of the "Plastic Body"

    ERIC Educational Resources Information Center

    Jordan, John W.

    2004-01-01

    This essay analyzes the "plastic body" as it is produced in the discourse of plastic surgery. The contemporary industry has constructed a popular image of plastic surgery as a readily available and personally empowering means to resolve body image issues, on the presumption that any body can become a "better" body. The ideology underlying the…

  17. 7 CFR 58.326 - Plastic cream.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

  18. 49 CFR 192.281 - Plastic pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Plastic pipe. (a) General. A plastic pipe joint that is joined by solvent cement, adhesive, or heat fusion..., see § 192.7). (3) The joint may not be heated to accelerate the setting of the cement. (c) Heat-fusion joints. Each heat-fusion joint on plastic pipe must comply with the following: (1) A butt heat-fusion...

  19. 49 CFR 192.281 - Plastic pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Plastic pipe. (a) General. A plastic pipe joint that is joined by solvent cement, adhesive, or heat fusion..., see § 192.7). (3) The joint may not be heated to accelerate the setting of the cement. (c) Heat-fusion joints. Each heat-fusion joint on plastic pipe must comply with the following: (1) A butt heat-fusion...

  20. 49 CFR 192.281 - Plastic pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Plastic pipe. (a) General. A plastic pipe joint that is joined by solvent cement, adhesive, or heat fusion..., see § 192.7). (3) The joint may not be heated to accelerate the setting of the cement. (c) Heat-fusion joints. Each heat-fusion joint on plastic pipe must comply with the following: (1) A butt heat-fusion...

  1. 49 CFR 192.281 - Plastic pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Plastic pipe. (a) General. A plastic pipe joint that is joined by solvent cement, adhesive, or heat fusion..., see § 192.7). (3) The joint may not be heated to accelerate the setting of the cement. (c) Heat-fusion joints. Each heat-fusion joint on plastic pipe must comply with the following: (1) A butt heat-fusion...

  2. 7 CFR 58.326 - Plastic cream.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

  3. 7 CFR 58.326 - Plastic cream.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

  4. 7 CFR 58.326 - Plastic cream.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

  5. Facile silicification of plastic surface for bioassays

    PubMed Central

    Hong, Seonki; Park, Ki Soo; Weissleder, Ralph; Castro, Cesar M.; Lee, Hakho

    2017-01-01

    We herein report a biomimetic technique to modify plastic substrates for bioassays. The method first places a polydopamine adhesion layer to plastic surface, and then grows conformal silica coating. As proof of principle, we coated plastic microbeads to construct a disposable filter for point-of-care nucleic acid extraction. PMID:28134385

  6. SUSTAINABLE PLASTICS: DESIGNING AND DEMONSTRATING RENEWABLE, BIODEGRADABLE PRODUCTS MADE OF SOY PROTEIN-BASED PLASTICS

    EPA Science Inventory

    We have found that soy protein plastics have flow properties that are comparable to fossil fuel-based plastics. Soy plastics are processed at much lower temperatures, however, yielding energy savings over synthetic plastics during processing. These comparable flow properties m...

  7. Elemental carbon and polycyclic aromatic compounds in a 150-year sediment core from Lake Qinghai, Tibetan Plateau, China: influence of regional and local sources and transport pathways.

    PubMed

    Han, Y M; Wei, C; Bandowe, B A M; Wilcke, W; Cao, J J; Xu, B Q; Gao, S P; Tie, X X; Li, G H; Jin, Z D; An, Z S

    2015-04-07

    Elemental carbon (EC) and polycyclic aromatic compounds (PACs) are potential proxies for the reconstruction of change in human activities and the origin of air masses in historic times. In this study, the historic deposition of char and soot (the two subtypes of EC) and PACs in a 150-year sediment core from different topographic subbasins of Lake Qinghai on the Qinghai Tibetan Plateau (QTP) were reconstructed. The objective was to explore how the variations in the concentrations of EC and PACs, in the ratios of char to soot and of oxygenated polycyclic aromatic hydrocarbons (OPAHs) to parent PAHs, and in the composition of the PAC mixtures reflect historical changes in climate and human activity and the origin of air masses arriving at the QTP. The deposition fluxes of soot in the different subbasins were similar, averaging 0.18 (range of 0.15-0.25) and 0.16 (0.13-0.23) g m(-2) year(-1), respectively, but they varied for char (averaging 0.11 and 0.22 g m(-2) year(-1), respectively), suggesting ubiquitous atmospheric deposition of soot and local river inputs of char. The different vertical distributions of the char/soot ratios in the different subbasins can be interpreted in terms of the different transport mechanisms of char and soot. An abrupt increase in soot concentrations since 1980 coincides with results from the QTP ice cores that were interpreted to be indicative of soot transport from South Asia. Similar concentration patterns of PAHs with soot and 9,10-anthraquinone/anthracene (9,10-AQ/ANT) ratios all >2.0 suggest regional PAC sources. Increasing PAH/soot ratios and decreasing 9,10-AQ/ANT ratios since the beginning of the 1970s indicate increasing local emissions. The historical trends of these diagnostic ratios indicate an increase in the fossil-fuel contribution since the beginning of the 1970s. The increase of perylene concentrations with increasing core depth and the ratio of perylene to its penta-aromatic isomers indicate that perylene originates

  8. Sleep and Plasticity in Schizophrenia

    PubMed Central

    Sprecher, Kate E.; Ferrarelli, Fabio

    2016-01-01

    Schizophrenia is a devastating mental illness with a worldwide prevalence of approximately 1 %. Although the clinical features of the disorder were described over one hundred years ago, its neurobiology is still largely elusive despite several decades of research. Schizophrenia is associated with marked sleep disturbances and memory impairment. Above and beyond altered sleep architecture, sleep rhythms including slow waves and spindles are disrupted in schizophrenia. In the healthy brain, these rhythms reflect and participate in plastic processes during sleep. This chapter discusses evidence that schizophrenia patients exhibit dysfunction of sleep-mediated plasticity on a behavioral, cellular, and molecular level and offers suggestions on how the study of sleeping brain activity can shed light on the pathophysiological mechanisms of the disorder. PMID:25608723

  9. Behavioural plasticity in evolving robots.

    PubMed

    Carvalho, Jônata Tyska; Nolfi, Stefano

    2016-12-01

    In this paper, we show how the development of plastic behaviours, i.e., behaviour displaying a modular organisation characterised by behavioural subunits that are alternated in a context-dependent manner, can enable evolving robots to solve their adaptive task more efficiently also when it does not require the accomplishment of multiple conflicting functions. The comparison of the results obtained in different experimental conditions indicates that the most important prerequisites for the evolution of behavioural plasticity are: the possibility to generate and perceive affordances (i.e., opportunities for behaviour execution), the possibility to rely on flexible regulatory processes that exploit both external and internal cues, and the possibility to realise smooth and effective transitions between behaviours.

  10. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1991-01-01

    This invention is comprised of a polishing compound for plastic materials. The compound includes approximately by approximately by weight 25 to 80 parts at least one petroleum distillate lubricant, 1 to 12 parts mineral spirits, 50 to 155 parts abrasive paste, and 15 to 60 parts water. Preferably, the compound includes approximately 37 to 42 parts at least one petroleum distillate lubricant, up to 8 parts mineral spirits, 95 to 110 parts abrasive paste, and 50 to 55 parts water. The proportions of the ingredients are varied in accordance with the particular application. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC), and similar plastic materials whenever a smooth, clear polished surface is desired.

  11. Temperature dependence of plastic scintillators

    NASA Astrophysics Data System (ADS)

    Peralta, L.

    2018-03-01

    Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

  12. Plastic biliary stents for benign biliary diseases.

    PubMed

    Perri, Vincenzo; Familiari, Pietro; Tringali, Andrea; Boskoski, Ivo; Costamagna, Guido

    2011-07-01

    Biliary plastic stenting plays a key role in the endoscopic management of benign biliary diseases. Complications following surgery of the biliary tract and liver transplantation are amenable to endoscopic treatment by plastic stenting. Insertion of an increasing number of plastic stents is currently the method of choice to treat postoperative biliary strictures. Benign biliary strictures secondary to chronic pancreatitis or primary sclerosing cholangitis may benefit from plastic stenting in select cases. There is a role for plastic stent placement in nonoperative candidates with acute cholecystitis and in patients with irretrievable bile duct stones. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Public health impact of plastics: An overview

    PubMed Central

    Rustagi, Neeti; Pradhan, S. K.; Singh, Ritesh

    2011-01-01

    Plastic, one of the most preferred materials in today's industrial world is posing serious threat to environment and consumer's health in many direct and indirect ways. Exposure to harmful chemicals during manufacturing, leaching in the stored food items while using plastic packages or chewing of plastic teethers and toys by children are linked with severe adverse health outcomes such as cancers, birth defects, impaired immunity, endocrine disruption, developmental and reproductive effects etc. Promotion of plastics substitutes and safe disposal of plastic waste requires urgent and definitive action to take care of this potential health hazard in future. PMID:22412286

  14. Process for remediation of plastic waste

    DOEpatents

    Pol, Vilas G; Thiyagarajan, Pappannan

    2013-11-12

    A single step process for degrading plastic waste by converting the plastic waste into carbonaceous products via thermal decomposition of the plastic waste by placing the plastic waste into a reactor, heating the plastic waste under an inert or air atmosphere until the temperature of about 700.degree. C. is achieved, allowing the reactor to cool down, and recovering the resulting decomposition products therefrom. The decomposition products that this process yields are carbonaceous materials, and more specifically carbon nanotubes having a partially filled core (encapsulated) adjacent to one end of the nanotube. Additionally, in the presence of a transition metal compound, this thermal decomposition process produces multi-walled carbon nanotubes.

  15. Process for remediation of plastic waste

    DOEpatents

    Pol, Vilas G [Westmont, IL; Thiyagarajan, Pappannan [Germantown, MD

    2012-04-10

    A single step process for degrading plastic waste by converting the plastic waste into carbonaceous products via thermal decomposition of the plastic waste by placing the plastic waste into a reactor, heating the plastic waste under an inert or air atmosphere until the temperature of 700.degree. C. is achieved, allowing the reactor to cool down, and recovering the resulting decomposition products therefrom. The decomposition products that this process yields are carbonaceous materials, and more specifically egg-shaped and spherical-shaped solid carbons. Additionally, in the presence of a transition metal compound, this thermal decomposition process produces multi-walled carbon nanotubes.

  16. The Plastic Surgery Hand Curriculum.

    PubMed

    Silvestre, Jason; Levin, L Scott; Serletti, Joseph M; Chang, Benjamin

    2015-12-01

    Designing an effective hand rotation for plastic surgery residents is difficult. The authors address this limitation by elucidating the critical components of the hand curriculum during plastic surgery residency. Hand questions on the Plastic Surgery In-Service Training Exam for six consecutive years (2008 to 2013) were characterized by presence of imaging, vignette setting, question taxonomy, answer domain, anatomy, and topic. Answer references were quantified by source and year of publication. Two hundred sixty-six questions were related to hand surgery (22.7 percent of all questions; 44.3 per year) and 61 were accompanied by an image (22.9 percent). Vignettes tended to be clinic- (50.0 percent) and emergency room-based (35.3 percent) (p < 0.001). Questions required decision-making (60.5 percent) over interpretation (25.9 percent) and recall skills (13.5 percent) (p < 0.001). Answers focused on interventions (57.5 percent) over anatomy/pathology (25.2 percent) and diagnoses (17.3 percent) (p < 0.001). Nearly half of the questions focused on the digits. The highest yield topics were trauma (35.3 percent), reconstruction (24.4 percent), and aesthetic and functional problems (14.2 percent). The Journal of Hand Surgery (American volume) (20.5 percent) and Plastic and Reconstructive Surgery (18.0 percent) were the most-cited journals, and the median publication lag was 7 years. Green's Operative Hand Surgery was the most-referenced textbook (41.8 percent). These results will enable trainees to study hand surgery topics with greater efficiency. Faculty can use these results to ensure that tested topics are covered during residency training. Thus, a benchmark is established to improve didactic, clinical, and operative experiences in hand surgery.

  17. The rise of plastic bioelectronics.

    PubMed

    Someya, Takao; Bao, Zhenan; Malliaras, George G

    2016-12-14

    Plastic bioelectronics is a research field that takes advantage of the inherent properties of polymers and soft organic electronics for applications at the interface of biology and electronics. The resulting electronic materials and devices are soft, stretchable and mechanically conformable, which are important qualities for interacting with biological systems in both wearable and implantable devices. Work is currently aimed at improving these devices with a view to making the electronic-biological interface as seamless as possible.

  18. The rise of plastic bioelectronics

    NASA Astrophysics Data System (ADS)

    Someya, Takao; Bao, Zhenan; Malliaras, George G.

    2016-12-01

    Plastic bioelectronics is a research field that takes advantage of the inherent properties of polymers and soft organic electronics for applications at the interface of biology and electronics. The resulting electronic materials and devices are soft, stretchable and mechanically conformable, which are important qualities for interacting with biological systems in both wearable and implantable devices. Work is currently aimed at improving these devices with a view to making the electronic-biological interface as seamless as possible.

  19. [Community survey of plastic surgery].

    PubMed

    Gao, Wei-Cheng; Yu, Yang; Ma, Shao-Lin

    2007-05-01

    A community survey was developed in order to analyses and assess the recognition of plastic surgery. And to provide some initial and useful evidence document for our other jobs. One thousand and one hundred individuals of various ages, either sex, different occupation and education levels, ethnically/racially diverse, social background, participated in this survey. All questionnaires were analyzed and chi-square analysis was performed for each question to compare the pattern of responses among the categories of respondents using the SPSS 11.5. Nine hundred and forty six individuals completed the survey (overall response rate 86%). Group 1 consisted of 342 general college students; The second group consisted of 427 medical college students; the third included 129 general practitioners, and 48 members of the general public comprised the fourth group of respondents. The results reveal that the majority of the crowd in the four groups needs more information about the benefits that our specialty can offer them. Despite the rapid progress that has occurred in the field of plastic surgery in the last 10 years, a large portion of the population is still unaware, even misunderstanding of the specialty. Therefore, they may not be taking advantage of the optimal care that is already available. And certainly, it also seriously hindrance the specialty. We should take effective methods to improve the advocacy from them. However, in our country, there is a scarcity of empirical evidence about the public perception of plastic surgery; this pilot study attempts to serve our jobs.

  20. Surface Enhancement For Optical Plastics

    NASA Astrophysics Data System (ADS)

    Masso, Jon D.

    1988-07-01

    Optical plastics can be molded or cast to replicate traditional spherical and aspheric lenses. It is possible to obtain good optical quality, but often it is necessary or desirable to enhance the surface characteristics in a variety of ways. These include improving the abrasion resistance, chemical resistance, the addition of anti-fog, or anti-static characteristics, applying electrically conductive coatings, and applying coatings or selective absorbers for light and color control. Coatings may be entirely organic or organo-silanes applied by dipping or spinning. All dielectric coatings such as quartz abrasion resistant coatings or multilayer dielectric coatings for reflection reduction or enhancement may be applied by vacuum vapor deposition. This paper discusses a number of these coatings and surface treatments. The paper describes their characteristics and includes discussions of their durability and environmental stability. The adhesion of coatings to plastic substrate depends on the specific substrate and coating materials. Pretreatments or primers are used to promote good coating adhesion. A coating used for one purpose will generally affect other properties of the plastic and trade-offs are sometimes required. A description is given of several test methods which have been found useful in evaluating the quality of the various coatings.

  1. Plastic solid waste utilization technologies: A Review

    NASA Astrophysics Data System (ADS)

    Awasthi, Arun Kumar; Shivashankar, Murugesh; Majumder, Suman

    2017-11-01

    Plastics are used in more number of applications in worldwide and it becomes essential part of our daily life. In Indian cities and villages people use the plastics in buying vegetable as a carry bag, drinking water bottle, use of plastic furniture in home, plastics objects uses in kitchen, plastic drums in packing and storage of the different chemicals for industrial use, use plastic utensils in home and many more uses. After usage of plastics it will become part of waste garbage and create pollution due to presence of toxic chemicals and it will be spread diseases and give birth to uncontrolled issues in social society. In current scenario consumption of plastic waste increasing day by day and it is very difficult to manage the plastic waste. There are limited methodologies available for reutilization of plastic waste again. Such examples are recycling, landfill, incineration, gasification and hydrogenation. In this paper we will review the existing methodologies of utilization of plastic waste in current scenario

  2. Applications and societal benefits of plastics.

    PubMed

    Andrady, Anthony L; Neal, Mike A

    2009-07-27

    This article explains the history, from 1600 BC to 2008, of materials that are today termed 'plastics'. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years.

  3. A review of plastic waste biodegradation.

    PubMed

    Zheng, Ying; Yanful, Ernest K; Bassi, Amarjeet S

    2005-01-01

    With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

  4. Do plastic surgeons have cosmetic surgery?

    PubMed

    Gurunluoglu, Raffi; Gurunluoglu, Aslin

    2009-12-01

    Thoughts and attitudes of plastic surgeons about having cosmetic surgery on themselves remain obscure for the most part and pose an attractive subject to study. A survey was distributed to a random sample of 2635 American Society of Plastic Surgeons member and candidate member surgeons to determine plastic surgeons' interest in both minimally invasive cosmetic procedures and cosmetic surgical procedures, selection of facility type, selection of surgeon, and their satisfaction level. There were 276 responses. Sixty-two percent of the plastic surgeons had undergone at least one type of minimally invasive cosmetic procedure. Female plastic surgeons had significantly more minimally invasive cosmetic procedures compared with male plastic surgeons (84.9 versus 57 percent; p < 0.05). The most common procedure was botulinum toxin type A injection (31.5 percent). Approximately one-third of plastic surgeons had at least one type of cosmetic surgery. The most common cosmetic surgical procedure was liposuction of the trunk and/or extremity (18.6 percent). Male plastic surgeons were more likely to have a procedure than men in the general population, and female plastic surgeons were less likely to have breast augmentation than the general population. The percentage of operations conducted by a plastic surgeon was 88.2 percent. The percentage performed by a nationally known surgeon was 45.3 percent; 75.9 percent of plastic surgeons selected a surgeon who was certified by the American Board of Plastic Surgery. The satisfaction rate was 90 percent. The survey provides insight on the stance of American Society of Plastic Surgeons member and candidate member surgeons on the subject. To the authors' knowledge, this is the first survey designed for this purpose.

  5. Characterization of plastic blends made from mixed plastics waste of different sources.

    PubMed

    Turku, Irina; Kärki, Timo; Rinne, Kimmo; Puurtinen, Ari

    2017-02-01

    This paper studies the recyclability of construction and household plastic waste collected from local landfills. Samples were processed from mixed plastic waste by injection moulding. In addition, blends of pure plastics, polypropylene and polyethylene were processed as a reference set. Reference samples with known plastic ratio were used as the calibration set for quantitative analysis of plastic fractions in recycled blends. The samples were tested for the tensile properties; scanning electron microscope-energy-dispersive X-ray spectroscopy was used for elemental analysis of the blend surfaces and Fourier transform infrared (FTIR) analysis was used for the quantification of plastics contents.

  6. Developmental plasticity and evolutionary biology.

    PubMed

    Bateson, Patrick

    2007-04-01

    Fetal experience determines some of the characteristics of human adults. Well-nourished mothers have offspring who are adapted to affluent conditions; mothers on a low level of nutrition have offspring who are adapted to lean environments. If the mother's forecast of her offspring's future environment is incorrect, the health of her offspring may suffer severely. The developmental plasticity that accounts for the ill health of humans who are living in conditions of rapid economic change is commonplace in biology. Understanding the evolutionary background sets the developmental origins of ill health in humans in context and has profound implications for public health.

  7. Cognitive Plasticity and Cortical Modules

    PubMed Central

    Mercado, Eduardo

    2009-01-01

    Some organisms learn to calculate, accumulate knowledge, and communicate in ways that others do not. What factors determine which intellectual abilities a particular species or individual can easily acquire? I propose that cognitive-skill learning capacity reflects (a) the availability of specialized cortical circuits, (b) the flexibility with which cortical activity is coordinated, and (c) the customizability of cortical networks. This framework can potentially account for differences in learning capacity across species, individuals, and developmental stages. Understanding the mechanisms that constrain cognitive plasticity is fundamental to developing new technologies and educational practices that maximize intellectual advancements. PMID:19750239

  8. Cognitive Plasticity and Cortical Modules.

    PubMed

    Mercado, Eduardo

    2009-06-01

    Some organisms learn to calculate, accumulate knowledge, and communicate in ways that others do not. What factors determine which intellectual abilities a particular species or individual can easily acquire? I propose that cognitive-skill learning capacity reflects (a) the availability of specialized cortical circuits, (b) the flexibility with which cortical activity is coordinated, and (c) the customizability of cortical networks. This framework can potentially account for differences in learning capacity across species, individuals, and developmental stages. Understanding the mechanisms that constrain cognitive plasticity is fundamental to developing new technologies and educational practices that maximize intellectual advancements.

  9. River plastic emissions to the world's oceans.

    PubMed

    Lebreton, Laurent C M; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia

    2017-06-07

    Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.

  10. Phenotypic plasticity in a population of odonates.

    PubMed

    Bowman, Randi M; Schmidt, Sharol; Weeks, Chelsea; Clark, Hunter; Brown, Christopher; Latta, Leigh C; Edgehouse, Michael

    2018-05-31

    The maintenance of phenotypic plasticity within a species ensures survival through environmental flux. Plastic strategies are increasingly important given the number and magnitude of modern anthropogenic threats to the environment. We tested for phenotypic plasticity in the odonate Argia vivida in response to resource limitation. By limiting food availability, effectively inducing hunger, we were able to quantify shifts in agonistic behavior during intraspecific interactions. Scoring behavior in one-on-one combat trials after 1 and 4 days without food revealed phenotypic plasticity. Three classes of genotypes were identified, genotypes exhibiting either increased aggression, decreased aggression, or no phenotypic plasticity, in response to resource limitation. The variable plastic strategies in this population of odonates likely aids in maintaining fitness in fluctuating environments.

  11. Applications and societal benefits of plastics

    PubMed Central

    Andrady, Anthony L.; Neal, Mike A.

    2009-01-01

    This article explains the history, from 1600 BC to 2008, of materials that are today termed ‘plastics’. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years. PMID:19528050

  12. Synaptic plasticity in drug reward circuitry.

    PubMed

    Winder, Danny G; Egli, Regula E; Schramm, Nicole L; Matthews, Robert T

    2002-11-01

    Drug addiction is a major public health issue worldwide. The persistence of drug craving coupled with the known recruitment of learning and memory centers in the brain has led investigators to hypothesize that the alterations in glutamatergic synaptic efficacy brought on by synaptic plasticity may play key roles in the addiction process. Here we review the present literature, examining the properties of synaptic plasticity within drug reward circuitry, and the effects that drugs of abuse have on these forms of plasticity. Interestingly, multiple forms of synaptic plasticity can be induced at glutamatergic synapses within the dorsal striatum, its ventral extension the nucleus accumbens, and the ventral tegmental area, and at least some of these forms of plasticity are regulated by behaviorally meaningful administration of cocaine and/or amphetamine. Thus, the present data suggest that regulation of synaptic plasticity in reward circuits is a tractable candidate mechanism underlying aspects of addiction.

  13. River plastic emissions to the world's oceans

    NASA Astrophysics Data System (ADS)

    Lebreton, Laurent C. M.; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia

    2017-06-01

    Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.

  14. Biodegradability of Plastics: Challenges and Misconceptions.

    PubMed

    Kubowicz, Stephan; Booth, Andy M

    2017-11-07

    Plastics are one of the most widely used materials and, in most cases, they are designed to have long life times. Thus, plastics contain a complex blend of stabilizers that prevent them from degrading too quickly. Unfortunately, many of the most advantageous properties of plastics such as their chemical, physical and biological inertness and durability present challenges when plastic is released into the environment. Common plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) are extremely persistent in the environment, where they undergo very slow fragmentation (projected to take centuries) into small particles through photo-, physical, and biological degradation processes 1 . The fragmentation of the material into increasingly smaller pieces is an unavoidable stage of the degradation process. Ultimately, plastic materials degrade to micron-sized particles (microplastics), which are persistent in the environment and present a potential source of harm for organisms.

  15. River plastic emissions to the world's oceans

    PubMed Central

    Lebreton, Laurent C. M.; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia

    2017-01-01

    Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies. PMID:28589961

  16. Constraints on the evolution of phenotypic plasticity: limits and costs of phenotype and plasticity

    PubMed Central

    Murren, C J; Auld, J R; Callahan, H; Ghalambor, C K; Handelsman, C A; Heskel, M A; Kingsolver, J G; Maclean, H J; Masel, J; Maughan, H; Pfennig, D W; Relyea, R A; Seiter, S; Snell-Rood, E; Steiner, U K; Schlichting, C D

    2015-01-01

    Phenotypic plasticity is ubiquitous and generally regarded as a key mechanism for enabling organisms to survive in the face of environmental change. Because no organism is infinitely or ideally plastic, theory suggests that there must be limits (for example, the lack of ability to produce an optimal trait) to the evolution of phenotypic plasticity, or that plasticity may have inherent significant costs. Yet numerous experimental studies have not detected widespread costs. Explicitly differentiating plasticity costs from phenotype costs, we re-evaluate fundamental questions of the limits to the evolution of plasticity and of generalists vs specialists. We advocate for the view that relaxed selection and variable selection intensities are likely more important constraints to the evolution of plasticity than the costs of plasticity. Some forms of plasticity, such as learning, may be inherently costly. In addition, we examine opportunities to offset costs of phenotypes through ontogeny, amelioration of phenotypic costs across environments, and the condition-dependent hypothesis. We propose avenues of further inquiry in the limits of plasticity using new and classic methods of ecological parameterization, phylogenetics and omics in the context of answering questions on the constraints of plasticity. Given plasticity's key role in coping with environmental change, approaches spanning the spectrum from applied to basic will greatly enrich our understanding of the evolution of plasticity and resolve our understanding of limits. PMID:25690179

  17. Stability of Glass Fiber-Plastic Composites

    DTIC Science & Technology

    1974-11-01

    miniiiii’ 5 0712 01016774 9 x TECHNICA. . LIBRARY Jt U*Al>/l 1 Technical Report RL-75-6 STABILITY OF GLASS FIBER -PLASTIC COMPOSITES Wartan A...Subtitle) STABILITY OF GLASS FIBER -PLASTIC COMPOSITES 5. TYPE OF REPORT & PERIOD COVERED Technical Report 6. PERFORMING ORG. REPORT NUMBER 7...Exploratory research was conducted to determine the stages and nature of degradation of glass fiber -plastic composite systems under various environmental

  18. Plastic Recycling Experiments in Materials Education

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, Tommy L.

    1996-01-01

    The objective of this project was to introduce a series of plastic recycling experiments to students in materials-related courses such as materials science, material technology and materials testing. With the plastic recycling experiments, students not only can learn the fundamentals of plastic processing and properties as in conventional materials courses, but also can be exposed to the issue of materials life cycle and the impact on society and environment.

  19. PLASTIC SCINTILLATOR FOR RADIATION DOSIMETRY.

    PubMed

    Kim, Yewon; Yoo, Hyunjun; Kim, Chankyu; Lim, Kyung Taek; Moon, Myungkook; Kim, Jongyul; Cho, Gyuseong

    2016-09-01

    Inorganic scintillators, composed of high-atomic-number materials such as the CsI(Tl) scintillator, are commonly used in commercially available a silicon diode and a scintillator embedded indirect-type electronic personal dosimeters because the light yield of the inorganic scintillator is higher than that of an organic scintillator. However, when it comes to tissue-equivalent dose measurements, a plastic scintillator such as polyvinyl toluene (PVT) is a more appropriate material than an inorganic scintillator because of the mass energy absorption coefficient. To verify the difference in the absorbed doses for each scintillator, absorbed doses from the energy spectrum and the calculated absorbed dose were compared. From the results, the absorbed dose of the plastic scintillator was almost the same as that of the tissue for the overall photon energy. However, in the case of CsI, it was similar to that of the tissue only for a photon energy from 500 to 4000 keV. Thus, the values and tendency of the mass energy absorption coefficient of the PVT are much more similar to those of human tissue than those of the CsI. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Psychoactive Drugs in Plastic Surgery

    PubMed Central

    Davison, Steven P.; Hayes, Kylie D.

    2017-01-01

    Background: Psychoactive drug use is on the rise in the United States, with plastic surgery patients a potentially susceptible group. This study aimed to determine the incidence of cosmetic and reconstructive patients in our practice taking psychoactive drugs and to compare those values with the national average. Furthermore, we discuss the patient safety concerns when patients withhold their medical history information over the course of their treatment. Methods: Urban private plastic practice patients who underwent surgery in a closed practice from 2009 to 2016 were divided into cosmetic and reconstructive cohorts. Review for drug use was medical scripts, history, and Surescripts drug reporting. Extracted information includes age, race, procedure, psychoactive medications, and whether or not they stated a mental health diagnosis on their medical history forms. Only patients with complete records were included. Results: A total of 830 patients were included in statistical analysis. Due to minimal cohort number, 70 men were excluded, as there were no comparative national data. Our analysis found that 33.6% cosmetic patients and 46.3% reconstructive patients used at least one psychoactive drug. Conclusion: There is a statistically significant difference between psychoactive drug use at our practice compared with the general population and a significantly larger percentage of reconstructive patients taking drugs compared with the cosmetic cohort. PMID:28458985

  1. Plasticity in the Interoceptive System.

    PubMed

    Torrealba, Fernando; Madrid, Carlos; Contreras, Marco; Gómez, Karina

    2017-01-01

    The most outstanding manifestations of the plastic capacities of brain circuits and their neuronal and synaptic components in the adult CNS are learning and memory. A reduced number of basic plastic mechanisms underlie learning capacities at many levels and regions of the brain. The interoceptive system is no exception, and some of the most studied behavioral changes that involve learning and memory engage the interoceptive pathways at many levels of their anatomical and functional organization.In this chapter, we will review four examples of learning, mostly in rats, where the interoceptive system has a role. In the case of conditioned taste aversion, the interoceptive system is of outstanding importance. In drug addiction, the role of the insular cortex - the highest level of the interoceptive system- is unusual and complex, as many forebrain regions are engaged by the process of addiction. In the third example, neophobia, the gustatory region of the insular cortex plays a major role. Finally, the role of different areas of the insular cortex in different processes of aversive memory, particularly fear conditioning, will be reviewed.

  2. Surface plasticity: theory and computation

    NASA Astrophysics Data System (ADS)

    Esmaeili, A.; Steinmann, P.; Javili, A.

    2017-11-01

    Surfaces of solids behave differently from the bulk due to different atomic rearrangements and processes such as oxidation or aging. Such behavior can become markedly dominant at the nanoscale due to the large ratio of surface area to bulk volume. The surface elasticity theory (Gurtin and Murdoch in Arch Ration Mech Anal 57(4):291-323, 1975) has proven to be a powerful strategy to capture the size-dependent response of nano-materials. While the surface elasticity theory is well-established to date, surface plasticity still remains elusive and poorly understood. The objective of this contribution is to establish a thermodynamically consistent surface elastoplasticity theory for finite deformations. A phenomenological isotropic plasticity model for the surface is developed based on the postulated elastoplastic multiplicative decomposition of the surface superficial deformation gradient. The non-linear governing equations and the weak forms thereof are derived. The numerical implementation is carried out using the finite element method and the consistent elastoplastic tangent of the surface contribution is derived. Finally, a series of numerical examples provide further insight into the problem and elucidate the key features of the proposed theory.

  3. Plastics processing: statistics, current practices, and evaluation.

    PubMed

    Cooke, F

    1993-11-01

    The health care industry uses a huge quantity of plastic materials each year. Much of the machinery currently used, or supplied, for plastics processing is unsuitable for use in a clean environment. In this article, the author outlines the reasons for the current situation and urges companies to re-examine their plastic-processing methods, whether performed in-house or subcontracted out. Some of the factors that should be considered when evaluating plastics-processing equipment are outlined to assist companies in remaining competitive and complying with impending EC regulations on clean room standards for manufacturing areas.

  4. Neuronal cytoskeleton in synaptic plasticity and regeneration.

    PubMed

    Gordon-Weeks, Phillip R; Fournier, Alyson E

    2014-04-01

    During development, dynamic changes in the axonal growth cone and dendrite are necessary for exploratory movements underlying initial axo-dendritic contact and ultimately the formation of a functional synapse. In the adult central nervous system, an impressive degree of plasticity is retained through morphological and molecular rearrangements in the pre- and post-synaptic compartments that underlie the strengthening or weakening of synaptic pathways. Plasticity is regulated by the interplay of permissive and inhibitory extracellular cues, which signal through receptors at the synapse to regulate the closure of critical periods of developmental plasticity as well as by acute changes in plasticity in response to experience and activity in the adult. The molecular underpinnings of synaptic plasticity are actively studied and it is clear that the cytoskeleton is a key substrate for many cues that affect plasticity. Many of the cues that restrict synaptic plasticity exhibit residual activity in the injured adult CNS and restrict regenerative growth by targeting the cytoskeleton. Here, we review some of the latest insights into how cytoskeletal remodeling affects neuronal plasticity and discuss how the cytoskeleton is being targeted in an effort to promote plasticity and repair following traumatic injury in the central nervous system. © 2013 International Society for Neurochemistry.

  5. Academic plastic surgery: faculty recruitment and retention.

    PubMed

    Chen, Jenny T; Girotto, John A; Kitzmiller, W John; Lawrence, W Thomas; Verheyden, Charles N; Vedder, Nicholas B; Coleman, John J; Bentz, Michael L

    2014-03-01

    A critical element of a thriving academic plastic surgery program is the quality of faculty. A decline in recruitment and retention of faculty has been attributed to the many challenges of academic medicine. Given the substantial resources required to develop faculty, academic plastic surgery has a vested interest in improving the process of faculty recruitment and retention. The American Council of Academic Plastic Surgeons Issues Committee and the American Society of Plastic Surgeons/Plastic Surgery Foundation Academic Affairs Council surveyed the 83 existing programs in academic plastic surgery in February of 2012. The survey addressed the faculty-related issues in academic plastic surgery programs over the past decade. Recruitment and retention strategies were evaluated. This study was designed to elucidate trends, and define best strategies, on a national level. Academic plastic surgery programs have added substantially more full-time faculty over the past decade. Recruitment efforts are multifaceted and can include guaranteed salary support, moving expenses, nurse practitioner/physician's assistant hires, protected time for research, seed funds to start research programs, and more. Retention efforts can include increased compensation, designation of a leadership appointment, protected academic time, and call dilution. Significant change and growth of academic plastic surgery has occurred in the past decade. Effective faculty recruitment and retention are critical to a successful academic center. Funding sources in addition to physician professional fees (institutional program support, grants, contracts, endowment, and so on) are crucial to sustain the academic missions.

  6. Interaction between vegetable oil based plasticizer molecules and polyvinyl chloride, and their plasticization effect

    NASA Astrophysics Data System (ADS)

    Haryono, Agus; Triwulandari, Evi; Jiang, Pingping

    2017-01-01

    Plasticizer molecules are low molecular weight compounds that are widely used in polymer industries especially in polyvinyl chloride (PVC) resin. As an additive in PVC resin, the important role of plasticizer molecules is to improve the flexibility and processability of PVC by lowering the glass transition temperature (Tg). However, the commercial plasticizer like di(2-ethylhexyl)phthalate (DEHP) is known to cause liver cancer, at least in laboratory rats. DEHP can leach out from PVC into blood, certain drug solutions and fatty foods, which has been detected in the bloodstream of patients undergoing transfusion. Vegetable oil based plasticizers have some attractive properties such as non-toxic, bio-degradable, good heat and light stability, renewable resources, and environmentally friendly. Here we discussed the main results and development of vegetable oil based plasticizer, and especially palm oil based plasticizer. The interaction between plasticizer and polymer was discussed from the properties of the plasticized polymeric material.

  7. Plasticizers derived from cardanol: Synthesis and plasticization properties for poly(vinyl chloride)

    USDA-ARS?s Scientific Manuscript database

    Two natural plasticizers derived from cardanol, cardanol acetate (CA), and epoxidized cardanol acetate (ECA), were synthesized and characterized by 1H NMR and 13C NMR. The plasticizing effects of the obtained plasticizers on semi-rigid polyvinyl chloride (PVC) formulations were also investigated. Tw...

  8. Melting the Plastic Ceiling: Overcoming Obstacles to Foster Leadership in Women Plastic Surgeons.

    PubMed

    Silva, Amanda K; Preminger, Aviva; Slezak, Sheri; Phillips, Linda G; Johnson, Debra J

    2016-09-01

    The underrepresentation of women leaders in plastic surgery echoes a phenomenon throughout society. The importance of female leadership is presented, and barriers to gender equality in plastic surgery, both intrinsic and extrinsic, are discussed. Strategies for fostering women in leadership on an individual level and for the specialty of plastic surgery are presented.

  9. Method to separate and recover oil and plastic from plastic contaminated with oil

    DOEpatents

    Smith, H.M.; Bohnert, G.W.; Olson, R.B.; Hand, T.E.

    1998-01-27

    The present invention provides a method to separate and recover oils and recyclable plastic from plastic contaminated with oil. The invention utilizes the different solubility of oil in a liquid or supercritical fluid as compared to a gas to effect separation of the oil from the plastic. 3 figs.

  10. Method to separate and recover oil and plastic from plastic contaminated with oil

    DOEpatents

    Smith, Henry M.; Bohnert, George W.; Olson, Ronald B.; Hand, Thomas E.

    1998-01-27

    The present invention provides a method to separate and recover oils and recyclable plastic from plastic contaminated with oil. The invention utilizes the different solubility of oil in as liquid or supercritical fluid as compared to a gas to effect separation of the oil from the plastic.

  11. Views of College Students on Plastic Surgery

    PubMed Central

    Ahmad, Muhammad; Mohmand, Humayun; Ahmad, Nabila

    2013-01-01

    BACKGROUND Various studies have been conducted in many countries to determine the perception/awareness about plastic surgery. The present study assessed the views of college students about plastic surgery. METHODS A questionnaire consisted of nine questions regarding the basic knowledge about plastic surgery was randomly distributed among college students. The students were given 20 minutes to fill out the forms. RESULTS A total of 250 male and 250 female college students were randomly included in the study. The mean age of the male students was 21.1 years as compared to 20.7 years of female students. The top five conditions named were related to hair (89.8%) followed by face scars (88%). The most common procedure named by the students was liposuction (88.2%) followed by hair transplantation. 80.2% of the students opted not to be a plastic surgeon if given an opportunity to select the profession. 33.8% of the students had seen some kinds of plastic surgery operation. Only 5.6% of the students (3.4% male and 2.2% female) had seen some kinds of plastic surgery procedure. 68% of male students and 48% of female students wished to have a plastic surgery procedure sometime in their lives. Majority of the students (88%) got the information from the internet. The second most common source was magazines (85.2%). Majority of the students (53.4%) had an idea of an invisible scar as a result of having a plastic surgery procedure. Only 22% thought to have no scar. Late Michael Jackson was at the top of the list of celebrities having a plastic surgery procedure (97.8%) followed by Nawaz Shariff (92.4%). CONCLUSION Despite the rapid growth of plastic surgery in the last two decades, a large portion of population remains unaware of the spatiality. It is essential to institute programs to educate healthcare consumers and providers about the plastic surgery. PMID:25489513

  12. Views of college students on plastic surgery.

    PubMed

    Ahmad, Muhammad; Mohmand, Humayun; Ahmad, Nabila

    2013-06-01

    Various studies have been conducted in many countries to determine the perception/awareness about plastic surgery. The present study assessed the views of college students about plastic surgery. A questionnaire consisted of nine questions regarding the basic knowledge about plastic surgery was randomly distributed among college students. The students were given 20 minutes to fill out the forms. A total of 250 male and 250 female college students were randomly included in the study. The mean age of the male students was 21.1 years as compared to 20.7 years of female students. The top five conditions named were related to hair (89.8%) followed by face scars (88%). The most common procedure named by the students was liposuction (88.2%) followed by hair transplantation. 80.2% of the students opted not to be a plastic surgeon if given an opportunity to select the profession. 33.8% of the students had seen some kinds of plastic surgery operation. Only 5.6% of the students (3.4% male and 2.2% female) had seen some kinds of plastic surgery procedure. 68% of male students and 48% of female students wished to have a plastic surgery procedure sometime in their lives. Majority of the students (88%) got the information from the internet. The second most common source was magazines (85.2%). Majority of the students (53.4%) had an idea of an invisible scar as a result of having a plastic surgery procedure. Only 22% thought to have no scar. Late Michael Jackson was at the top of the list of celebrities having a plastic surgery procedure (97.8%) followed by Nawaz Shariff (92.4%). Despite the rapid growth of plastic surgery in the last two decades, a large portion of population remains unaware of the spatiality. It is essential to institute programs to educate healthcare consumers and providers about the plastic surgery.

  13. Molecular Signaling in Muscle Plasticity

    NASA Technical Reports Server (NTRS)

    Epstein, Henry F.

    1999-01-01

    Extended spaceflight under microgravity conditions leads to significant atrophy of weight-bearing muscles. Atrophy and hypertrophy are the extreme outcomes of the high degree of plasticity exhibited by skeletal muscle. Stimuli which control muscle plasticity include neuronal, hormonal, nutritional, and mechanical inputs. The mechanical stimulus for muscle is directly related to the work or exercise against a load performed. Little or no work is performed by weight-bearing muscles under microgravity conditions. A major hypothesis is that focal adhesion kinase (FAK) which is associated with integrin at the adherens junctions and costa meres of all skeletal muscles is an integral part of the major mechanism for molecular signaling upon mechanical stimulation in all muscle fibers. Additionally, we propose that myotonic protein kinase (DMPK) and dystrophin (DYSTR) also participate in distinct mechanically stimulated molecular signaling pathways that are most critical in type I and type II muscle fibers, respectively. To test these hypotheses, we will use the paradigms of hindlimb unloading and overloading in mice as models for microgravity conditions and a potential exercise countermeasure, respectively, in mice. We expect that FAK loss-of-function will impair hypertrophy and enhance atrophy in all skeletal muscle fibers whereas DYSTR and DMPK loss-of-function will have similar but more selective effects on Type IT and Type I fibers, respectively. Gene expression will be monitored by muscle-specific creatine kinase M promoter-reporter construct activity and specific MRNA and protein accumulation in the soleus (type I primarily) and plantaris (type 11 primarily) muscles. With these paradigms and assays, the following Specific Project Aims will be tested in genetically altered mice: 1) identify the roles of DYSTR and its pathway; 2) evaluate the roles of the DMPK and its pathway; 3) characterize the roles of FAK and its pathway and 4) genetically analyze the mechanisms

  14. SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

    SciTech Connect

    Vijayan, S; Rana, V; Nagesh, S Setlur

    Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detectormore » was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.« less

  15. Manufacturing plastic injection optical molds

    NASA Astrophysics Data System (ADS)

    Bourque, David

    2008-08-01

    ABCO Tool & Die, Inc. is a mold manufacturer specializing in the manufacturing of plastic injection molds for molded optical parts. The purpose of this presentation is to explain the concepts and procedures required to build a mold that produces precision optical parts. Optical molds can produce a variety of molded parts ranging from safety eyewear to sophisticated military lens parts, which must meet precise optical specifications. The manufacturing of these molds begins with the design engineering of precision optical components. The mold design and the related optical inserts are determined based upon the specific optical criteria and optical surface geometry. The mold manufacturing techniques will be based upon the optical surface geometry requirements and specific details. Manufacturing processes used will be specific to prescribed geometrical surface requirements of the molded part. The combined efforts result in a robust optical mold which can produce molded parts that meet the most precise optical specifications.

  16. Neuronal plasticity and antidepressant actions

    PubMed Central

    Castrén, Eero; Hen, René

    2013-01-01

    Antidepressant treatments enhance plasticity and increase neurogenesis in the adult brain, but it has been unclear how these effects influence mood. We propose that like environmental enrichment and exercise, antidepressant treatments enhance adaptability by increasing structural variability within the nervous system at many levels, from proliferating precursors to immature synaptic contacts. Conversely, sensory deprivation and chronic stress reduce this structural variability. Activity-dependent competition within the mood-related circuits, guided by rehabilitation, then selects for the survival and stabilization of those structures that best represent the internal or external milieu. Increased variability together with competition-mediated selection facilitates normal function, such as pattern separation within the dentate gyrus and other mood-related circuits, thereby enhancing adaptability towards novel experiences. PMID:23380665

  17. ECM remodeling and its plasticity

    NASA Astrophysics Data System (ADS)

    Feng, Jingchen; Jones, Christopher A. R.; Cibula, Matthew; Mao, Xiaoming; Sander, Leonard M.; Levine, Herbert; Sun, Bo

    The mechanical interactions between cells and Extracellular Matrix (ECM) are of great importance in many cellular processes. These interactions are reciprocal, i.e. contracting cells pull and reorganize the surrounding matrix, while the remodeled matrix feeds back to regulate cell activities. Recent experiments show in collagen gels with densely distributed cells, aligned fiber bundles are formed in the direction between neighboring cells. Fibers flow into the center region between contracting cell pairs in this process, which causes the concentration of fibers in the fiber bundles to become significantly enhanced. Using an extended lattice-based model, we show that viscoelasticity plays an essential role in ECM remodeling and contributes to the enhanced concentration in fiber bundles. We further characterize ECM plasticity within our model and verify our results with rheometer experiments.

  18. A Conservative Formulation for Plasticity

    DTIC Science & Technology

    1992-01-01

    UNCLASSIFIED UL NSN 7540-01-280-5500 Standard C -- -9P ’Rev 2 P1’su1ba Or AN-YS SI I AI) V -\\ -’ IsiN 17 l1 I IM 1 \\I f fi S 1i t i I 1( , 13. 402 -493...2.24) and (2.25) has been suggested by Frangenstcin and Colella [34], viz., the equality of mixed partial derivatiXes for d ) - a + [g"-, v ] = 0. (2.26...gradient nor plastic flow (i.e.. T = 0. E,’, = 0. and K = 0). inequality (3.12) leads to the identifications __ P -- - (3.13) and T (3.14) d S along with

  19. Perceptual Grouping Enhances Visual Plasticity

    PubMed Central

    Mastropasqua, Tommaso; Turatto, Massimo

    2013-01-01

    Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity. PMID:23301100

  20. Evolutionary plasticity of insect immunity.

    PubMed

    Vilcinskas, Andreas

    2013-02-01

    Many insect genomes have been sequenced and the innate immune responses of several species have been studied by transcriptomics, inviting the comparative analysis of immunity-related genes. Such studies have demonstrated significant evolutionary plasticity, with the emergence of novel proteins and protein domains correlated with insects adapting to both abiotic and biotic environmental stresses. This review article focuses on effector molecules such as antimicrobial peptides (AMPs) and proteinase inhibitors, which display greater evolutionary dynamism than conserved components such as immunity-related signaling molecules. There is increasing evidence to support an extended role for insect AMPs beyond defense against pathogens, including the management of beneficial endosymbionts. The total number of AMPs varies among insects with completed genome sequences, providing intriguing examples of immunity gene expansion and loss. This plasticity is discussed in the context of recent developments in evolutionary ecology suggesting that the maintenance and deployment of immune responses reallocates resources from other fitness-related traits thus requiring fitness trade-offs. Based on our recent studies using both model and non-model insects, I propose that insect immunity genes can be lost when alternative defense strategies with a lower fitness penalty have evolved, such as the so-called social immunity in bees, the chemical sanitation of the microenvironment by some beetles, and the release of antimicrobial secondary metabolites in the hemolymph. Conversely, recent studies provide evidence for the expansion and functional diversification of insect AMPs and proteinase inhibitors to reflect coevolution with a changing pathosphere and/or adaptations to habitats or food associated with microbial contamination. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Augmentation-related brain plasticity

    PubMed Central

    Di Pino, Giovanni; Maravita, Angelo; Zollo, Loredana; Guglielmelli, Eugenio; Di Lazzaro, Vincenzo

    2014-01-01

    Today, the anthropomorphism of the tools and the development of neural interfaces require reconsidering the concept of human-tools interaction in the framework of human augmentation. This review analyses the plastic process that the brain undergoes when it comes into contact with augmenting artificial sensors and effectors and, on the other hand, the changes that the use of external augmenting devices produces in the brain. Hitherto, few studies investigated the neural correlates of augmentation, but clues on it can be borrowed from logically-related paradigms: sensorimotor training, cognitive enhancement, cross-modal plasticity, sensorimotor functional substitution, use and embodiment of tools. Augmentation modifies function and structure of a number of areas, i.e., primary sensory cortices shape their receptive fields to become sensitive to novel inputs. Motor areas adapt the neuroprosthesis representation firing-rate to refine kinematics. As for normal motor outputs, the learning process recruits motor and premotor cortices and the acquisition of proficiency decreases attentional recruitment, focuses the activity on sensorimotor areas and increases the basal ganglia drive on the cortex. Augmentation deeply relies on the frontoparietal network. In particular, premotor cortex is involved in learning the control of an external effector and owns the tool motor representation, while the intraparietal sulcus extracts its visual features. In these areas, multisensory integration neurons enlarge their receptive fields to embody supernumerary limbs. For operating an anthropomorphic neuroprosthesis, the mirror system is required to understand the meaning of the action, the cerebellum for the formation of its internal model and the insula for its interoception. In conclusion, anthropomorphic sensorized devices can provide the critical sensory afferences to evolve the exploitation of tools through their embodiment, reshaping the body representation and the sense of the self

  2. Perceptual grouping enhances visual plasticity.

    PubMed

    Mastropasqua, Tommaso; Turatto, Massimo

    2013-01-01

    Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity.

  3. Industrial Arts Curriculum Guide for Plastics.

    ERIC Educational Resources Information Center

    Connecticut State Dept. of Education, Hartford. Div. of Vocational Education.

    This curriculum guide provides topic outlines and objectives for 12 units of an industrial arts program in plastics at any grade level. Introductory material describes the scope and sequence of an Industrial Arts program, gives specific guidelines for Industrial Arts, and briefly discusses the nature of plastics. Unit titles include Orientation of…

  4. Fabrication of plastic microparts on wafer level

    NASA Astrophysics Data System (ADS)

    Weber, Lutz; Ehrfeld, Wolfgang; Begemann, Marc; Berg, Udo; Michel, Frank

    1999-08-01

    In the recent years micromolding has become one of the most important key technologies of microengineering. At the current state of art, the mass fabrication of plastic microparts for a wide range of applications like telecommunications, sensors, medical technology and biochemistry is feasible. Here a micro motor, plastic optical waveguides, a micro pump, and nanotiterplates are presented.

  5. Fuels from pyrolysis of waste plastic

    USDA-ARS?s Scientific Manuscript database

    A large quantity of carbon containing materials, such as waste plastic, used tires, food waste, and biomass end up in landfills. These materials represent a rich energy source that is currently untapped or underutilized. Municipal solid waste is comprised of 12% waste plastic, but only a small fract...

  6. Plastic Accumulation in the Mediterranean Sea

    PubMed Central

    Cózar, Andrés; Sanz-Martín, Marina; Martí, Elisa; González-Gordillo, J. Ignacio; Ubeda, Bárbara; Gálvez, José Á.; Irigoien, Xabier; Duarte, Carlos M.

    2015-01-01

    Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region. PMID:25831129

  7. Plastic-aluminum composites in transportation infrastructure.

    DOT National Transportation Integrated Search

    2017-03-01

    This report presents an initial investigation of the mechanics of I-beams developed with plastic-aluminum composite technology. Plastic-aluminum composites in structural beam/frame/truss elements are a relatively new concept that has seen little, if ...

  8. Marine Debris and Plastic Source Reduction Toolkit

    EPA Pesticide Factsheets

    Many plastic food service ware items originate on college and university campuses—in cafeterias, snack rooms, cafés, and eateries with take-out dining options. This Campus Toolkit is a detailed “how to” guide for reducing plastic waste on college campuses.

  9. Plastic accumulation in the Mediterranean sea.

    PubMed

    Cózar, Andrés; Sanz-Martín, Marina; Martí, Elisa; González-Gordillo, J Ignacio; Ubeda, Bárbara; Gálvez, José Á; Irigoien, Xabier; Duarte, Carlos M

    2015-01-01

    Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region.

  10. Electromagnetic bonding of plastics to aluminum

    NASA Technical Reports Server (NTRS)

    Sheppard, A. T.; Silbert, L.

    1980-01-01

    Electromagnetic curing is used to bond strain gage to aluminum tensile bar. Electromagnetic energy heats only plastic/metal interface by means of skin effect, preventing degradation of heat-treated aluminum. Process can be easily applied to other metals joined by high-temperature-curing plastic adhesives.

  11. COMPOSITES FROM RECYCLED WOOD AND PLASTICS

    EPA Science Inventory

    The ultimate goal of this research was to develop technology to convert recycled wood fiber and plastics into durable products that are recyclable and otherwise environmentally friendly. Two processing technologies were used to prepare wood-plastic composites: air-laying and melt...

  12. COMPOSITES FROM RECYCLED WOOD AND PLASTICS

    EPA Science Inventory

    The ultimate goal of this research was to develop technology to convert recycled wood fiber and plastics into durable products that are recyclable and otherwise environmentally friendly. wo processing technologies were used to prepare wood-plastic composites: air-laying and melt-...

  13. Biological degradation of plastics: a comprehensive review.

    PubMed

    Shah, Aamer Ali; Hasan, Fariha; Hameed, Abdul; Ahmed, Safia

    2008-01-01

    Lack of degradability and the closing of landfill sites as well as growing water and land pollution problems have led to concern about plastics. With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. The interest in environmental issues is growing and there are increasing demands to develop material which do not burden the environment significantly. Biodegradation is necessary for water-soluble or water-immiscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires understanding of the interactions between materials and microorganisms and the biochemical changes involved. Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. This paper reviews the current research on the biodegradation of biodegradable and also the conventional synthetic plastics and also use of various techniques for the analysis of degradation in vitro.

  14. Starch plastics packaging and agriculture applications

    USDA-ARS?s Scientific Manuscript database

    The environmental impact of petroleum-based plastics is a growing concern throughout the world. Containers and packaging comprise the largest sector of municipal solid waste and are a major component of pollution on both land and sea. Although the benefits of plastics in many consumer and industrial...

  15. Microwave interferometer controls cutting depth of plastics

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.

    1969-01-01

    Microwave interferometer system controls the cutting of plastic materials to a prescribed depth. The interferometer is mounted on a carriage with a spindle and cutting tool. A cross slide, mounted on the carriage, allows the interferometer and cutter to move toward or away from the plastic workpiece.

  16. Integrating Hebbian and homeostatic plasticity: introduction.

    PubMed

    Fox, Kevin; Stryker, Michael

    2017-03-05

    Hebbian plasticity is widely considered to be the mechanism by which information can be coded and retained in neurons in the brain. Homeostatic plasticity moves the neuron back towards its original state following a perturbation, including perturbations produced by Hebbian plasticity. How then does homeostatic plasticity avoid erasing the Hebbian coded information? To understand how plasticity works in the brain, and therefore to understand learning, memory, sensory adaptation, development and recovery from injury, requires development of a theory of plasticity that integrates both forms of plasticity into a whole. In April 2016, a group of computational and experimental neuroscientists met in London at a discussion meeting hosted by the Royal Society to identify the critical questions in the field and to frame the research agenda for the next steps. Here, we provide a brief introduction to the papers arising from the meeting and highlight some of the themes to have emerged from the discussions.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'. © 2017 The Author(s).

  17. DEVELOPING SUSTAINABLE ALTERNATIVES TO PLASTIC MULCH

    EPA Science Inventory

    We propose a project to raise awareness of pollution associated with the production, use and disposal of plastic films/ sheeting used as mulch, and to work with farmers and industry partners to develop a biodegradable, sustainable alternative to plastic mulch.

  18. Demonstrating Fluorescence with Neon Paper and Plastic

    ERIC Educational Resources Information Center

    Birriel, Jennifer J.; Roe, Clarissa

    2015-01-01

    Several papers in this journal have dealt with the fluorescence in orange neon plastic, olive oil, and soda. In each case, the fluorescent emission was excited by either green or violet-blue laser light. In this paper, we examine the fluorescent emission spectra of so-called neon colored papers and plastic clipboards available in department and…

  19. Nano-plastics in the aquatic environment.

    PubMed

    Mattsson, K; Hansson, L-A; Cedervall, T

    2015-10-01

    The amount of plastics released to the environment in modern days has increased substantially since the development of modern plastics in the early 1900s. As a result, concerns have been raised by the public about the impact of plastics on nature and on, specifically, aquatic wildlife. Lately, much attention has been paid to macro- and micro-sized plastics and their impact on aquatic organisms. However, micro-sized plastics degrade subsequently into nano-sizes whereas nano-sized particles may be released directly into nature. Such particles have a different impact on aquatic organisms than larger pieces of plastic due to their small size, high surface curvature, and large surface area. This review describes the possible sources of nano-sized plastic, its distribution and behavior in nature, the impact of nano-sized plastic on the well-being of aquatic organisms, and the difference of impact between nano- and micro-sized particles. We also identify research areas which urgently need more attention and suggest experimental methods to obtain useful data.

  20. Liquid crystal displays with plastic substrates

    NASA Astrophysics Data System (ADS)

    Lueder, Ernst H.

    1998-04-01

    Plastic substrates for the cells of displays exhibit only 1/6 of the weight of glass substrates; they are virtually unbreakable; their flexibility allows the designer to give them a shape suppressing reflections, to realize a display board on a curved surface or meeting the requirements for an appealing styling; displays with plastics are thinner which provides a wider viewing angle. These features render them attractive for displays in portable systems such as mobile phones, pagers, smart cards, personal digital assistants (PDAs) and portable computers. Reflective displays are especially attractive as they don't need a back light. The most important requirements are the protection of plastics against gas permeation and chemical agents, the prevention of layers on plastics to crack or peel off when the plastic is bent and the development of low temperature thin film processes because the plastics, as a rule, only tolerate temperatures below 150 degrees Celsius. Bistable reflective FLC- and PSCT-displays with plastic substrates will be introduced. Special sputtered SiO2-orientation layers preserve the displayed information even if pressure or torsion is applied. MIM-addressed PDLC-displays require additional Al- or Ti-layers which provide the necessary ductility. Sputtered or PECVD-generated TFTs can be fabricated on plastics at temperatures below 150 degrees Celsius.

  1. 49 CFR 192.59 - Plastic pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.59 Plastic pipe. (a) New plastic pipe...

  2. Industrial plastics waste: Identification and segregation

    NASA Technical Reports Server (NTRS)

    Widener, Edward L.

    1990-01-01

    Throwaway plastic products, mainly packaging, are inundating our landfills and incinerators. Most are ethenic thermoplastics, which can be recycled as new products or fossil-fuels. Lab experiments are described, involving destructive and non-destructive tests for identifying and using plastics. The burn-test, with simple apparatus and familiar samples, is recommended as quick, cheap and effective.

  3. Gas Property Demonstrations Using Plastic Water Bottles

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Bannon, Stephen J.; Gunter, Molly M.

    2011-01-01

    Plastic water bottles are convenient containers for demonstrations of gas properties illustrating Boyle's law, Charles's law, and Avogadro's law. The contents of iron-based disposable hand warmer packets can be used to remove oxygen gas from the air within an unfilled plastic water bottle.

  4. [Survey of plasticizers in polyvinyl chloride toys].

    PubMed

    Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Yoko

    2012-01-01

    Plasticizers in 101 samples of polyvinyl chloride (PVC) toys on the Japanese market were surveyed. No phthalates were detected in designated toys, though bis(2-ethylhexyl)phthalate, diisononyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisodecyl phthalate and benzyl butyl phthalate were detected in more than half of other toys. 2,2,4-Tributyl-1,3-pentanediol diisobutylate, o-acetyl tributyl citrate, adipates and diacetyl lauroyl glycerol, which are alternative plasticizers to phthalates, were detected. The results of structural analysis confirmed the presence of di(2-ethylhexyl)terephthalate, tributyl citrate, diisononyl 1,2-cyclohexanedicarboxylate and neopentyl glycol esters; these have not previonsly been reported in Japan. There appears to be a shift in plasticizers used for designated toys from phthalates to new plasticizers, and the number of different plasticizers is increasing.

  5. Phyllosphere yeasts rapidly break down biodegradable plastics.

    PubMed

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-Hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-11-29

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

  6. Nanoparticles from Degradation of Biodegradable Plastic Mulch

    NASA Astrophysics Data System (ADS)

    Flury, Markus; Sintim, Henry; Bary, Andy; English, Marie; Schaefer, Sean

    2017-04-01

    Plastic mulch films are commonly used in crop production. They provide multiple benefits, including control of weeds and insects, increase of soil and air temperature, reduction of evaporation, and prevention of soil erosion. The use of plastic mulch film in agriculture has great potential to increase food production and security. Plastic mulch films must be retrieved and disposed after usage. Biodegradable plastic mulch films, who can be tilled into the soil after usage offer great benefits as alternative to conventional polyethylene plastic. However, it has to be shown that the degradation of these mulches is complete and no micro- and nanoparticles are released during degradation. We conducted a field experiment with biodegradable mulches and tested mulch degradation. Mulch was removed from the field after the growing season and composted to facilitate degradation. We found that micro- and nanoparticles were released during degradation of the mulch films in compost. This raises concerns about degradation in soils as well.

  7. Leaching of plastic additives to marine organisms.

    PubMed

    Koelmans, Albert A; Besseling, Ellen; Foekema, Edwin M

    2014-04-01

    It is often assumed that ingestion of microplastics by aquatic species leads to increased exposure to plastic additives. However, experimental data or model based evidence is lacking. Here we assess the potential of leaching of nonylphenol (NP) and bisphenol A (BPA) in the intestinal tracts of Arenicola marina (lugworm) and Gadus morhua (North Sea cod). We use a biodynamic model that allows calculations of the relative contribution of plastic ingestion to total exposure of aquatic species to chemicals residing in the ingested plastic. Uncertainty in the most crucial parameters is accounted for by probabilistic modeling. Our conservative analysis shows that plastic ingestion by the lugworm yields NP and BPA concentrations that stay below the lower ends of global NP and BPA concentration ranges, and therefore are not likely to constitute a relevant exposure pathway. For cod, plastic ingestion appears to be a negligible pathway for exposure to NP and BPA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Sacrificial plastic mold with electroplatable base

    DOEpatents

    Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

    2002-01-01

    A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  9. Castable plastic mold with electroplatable base

    DOEpatents

    Domeier, Linda A.; Morales, Alfredo M.; Gonzales, Marcela G.; Keifer, Patrick M.

    2004-01-20

    A sacrificial plastic mold having an electroplatable backing is provided as are methods of making such a mold via the infusion of a castable liquid formulation through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale master mold. Upon casting and demolding, the porous metal substrate is embedded within the cast formulation and projects a plastic structure with features determined by the mold tool. The plastic structure provides a sacrificial plastic mold mechanically bonded to the porous metal substrate, which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved, leaving the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  10. Sacrificial Plastic Mold With Electroplatable Base

    DOEpatents

    Domeier, Linda A.; Hruby, Jill M.; Morales, Alfredo M.

    2005-08-16

    A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

  11. Plastics and Environmental Health: The Road Ahead

    PubMed Central

    North, Emily J.; Halden, Rolf U.

    2013-01-01

    Plastics continue to benefit society in innumerable ways, even though recent public focus on plastics has centered mostly on human health and environmental concerns, including endocrine-disrupting properties and long-term pollution. The benefits of plastics are particularly apparent in medicine and public health. Plastics are versatile, cost-effective, require less energy to produce than alternative materials – such as metal or glass – and can be manufactured to have many different properties. Due to these characteristics, polymers are used in diverse health applications, such as disposable syringes and intravenous bags, sterile packaging for medical instruments as well as in joint replacements, tissue engineering, etc. However, not all current uses of plastics are prudent and sustainable, as illustrated by widespread, unwanted human exposure to endocrine-disrupting bisphenol-A (BPA) and di-(2-ethylhexyl)phthalate (DEHP), problems arising from the large quantities of plastic being disposed of, and depletion of non-renewable petroleum resources as a result of ever increasing mass-production of plastic consumer articles. By example of the healthcare sector, this review concentrates on benefits and downsides of plastics and identities opportunities to change the composition and disposal practices of these invaluable polymers for a more sustainable future consumption. It highlights ongoing efforts to phase out DEHP and BPA in the healthcare and food industry, and discusses biodegradable options for plastic packaging, opportunities for reducing plastic medical waste, and recycling in medical facilities in the quest to reap a maximum of benefits from polymers without compromising human health or the environment in the process. PMID:23337043

  12. Plastics and environmental health: the road ahead.

    PubMed

    North, Emily J; Halden, Rolf U

    2013-01-01

    Plastics continue to benefit society in innumerable ways, even though recent public focus on plastics has centered mostly on human health and environmental concerns, including their endocrine-disrupting properties and the long-term pollution they represent. The benefits of plastics are particularly apparent in medicine and public health. Plastics are versatile, cost-effective, require less energy to produce than alternative materials like metal or glass, and can be manufactured to have many different properties. Due to these characteristics, polymers are used in diverse health applications like disposable syringes and intravenous bags, sterile packaging for medical instruments as well as in joint replacements, tissue engineering, etc. However, not all current uses of plastics are prudent and sustainable, as illustrated by the widespread, unwanted human exposure to endocrine-disrupting bisphenol A (BPA) and di-(2-ethylhexyl)phthalate (DEHP), problems arising from the large quantities of plastic being disposed of, and depletion of non-renewable petroleum resources as a result of the ever-increasing mass production of plastic consumer articles. Using the health-care sector as example, this review concentrates on the benefits and downsides of plastics and identifies opportunities to change the composition and disposal practices of these invaluable polymers for a more sustainable future consumption. It highlights ongoing efforts to phase out DEHP and BPA in the health-care and food industry and discusses biodegradable options for plastic packaging, opportunities for reducing plastic medical waste, and recycling in medical facilities in the quest to reap a maximum of benefits from polymers without compromising human health or the environment in the process.

  13. Recycling of plastic waste: Presence of phthalates in plastics from households and industry.

    PubMed

    Pivnenko, K; Eriksen, M K; Martín-Fernández, J A; Eriksson, E; Astrup, T F

    2016-08-01

    Plastics recycling has the potential to substitute virgin plastics partially as a source of raw materials in plastic product manufacturing. Plastic as a material may contain a variety of chemicals, some potentially hazardous. Phthalates, for instance, are a group of chemicals produced in large volumes and are commonly used as plasticisers in plastics manufacturing. Potential impacts on human health require restricted use in selected applications and a need for the closer monitoring of potential sources of human exposure. Although the presence of phthalates in a variety of plastics has been recognised, the influence of plastic recycling on phthalate content has been hypothesised but not well documented. In the present work we analysed selected phthalates (DMP, DEP, DPP, DiBP, DBP, BBzP, DEHP, DCHP and DnOP) in samples of waste plastics as well as recycled and virgin plastics. DBP, DiBP and DEHP had the highest frequency of detection in the samples analysed, with 360μg/g, 460μg/g and 2700μg/g as the maximum measured concentrations, respectively. Among other, statistical analysis of the analytical results suggested that phthalates were potentially added in the later stages of plastic product manufacturing (labelling, gluing, etc.) and were not removed following recycling of household waste plastics. Furthermore, DEHP was identified as a potential indicator for phthalate contamination of plastics. Close monitoring of plastics intended for phthalates-sensitive applications is recommended if recycled plastics are to be used as raw material in production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. AIR KERMA TO Hp(3) CONVERSION COEFFICIENTS FOR IEC 61267 RQR X-RAY RADIATION QUALITIES: APPLICATION TO DOSE MONITORING OF THE LENS OF THE EYE IN MEDICAL DIAGNOSTICS.

    PubMed

    Principi, S; Guardiola, C; Duch, M A; Ginjaume, M

    2016-09-01

    Recent studies highlight the fact that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens monitoring could be required for these workers. The recommended operational quantity for monitoring of eye lens exposure is the personal dose equivalent at 3 mm depth Hp(3) (ICRU 51). However, there are no available conversion coefficients in international standards, while in the literature coefficients have only been calculated for monoenergetic beams and for ISO 4037-1 X-ray qualities. The aim of this article is to provide air kerma to Hp(3) conversion coefficients for a cylindrical phantom made of ICRU-4 elements tissue-equivalent material for RQR radiation qualities (IEC-61267) from 40 to 120 kV and for angles of incidence from 0 to 180°, which are characteristic of medical workplace. Analytic calculations using interpolation techniques and Monte Carlo modelling have been compared. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Phenotypic plasticity with instantaneous but delayed switches.

    PubMed

    Utz, Margarete; Jeschke, Jonathan M; Loeschcke, Volker; Gabriel, Wilfried

    2014-01-07

    Phenotypic plasticity is a widespread phenomenon, allowing organisms to better adapt to changing environments. Most empirical and theoretical studies are restricted to irreversible plasticity where the expression of a specific phenotype is mostly determined during development. However, reversible plasticity is not uncommon; here, organisms are able to switch back and forth between phenotypes. We present two optimization models for the fitness of (i) non-plastic, (ii) irreversibly plastic, and (iii) reversibly plastic genotypes in a fluctuating environment. In one model, the fitness values of an organism during different life phases act together multiplicatively (so as to consider traits that are related to survival). The other model additionally considers additive effects (corresponding to traits related to fecundity). Both models yield qualitatively similar results. If the only costs of reversible plasticity are due to temporal maladaptation while switching between phenotypes, reversibility is virtually always advantageous over irreversibility, especially for slow environmental fluctuations. If reversibility implies an overall decreased fitness, then irreversibility is advantageous if the environment fluctuates quickly or if stress events last relatively short. Our results are supported by observations from different types of organisms and have implications for many basic and applied research questions, e.g., on invasive alien species. © 2013 Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.

  16. Morphological plasticity of bacteria—Open questions

    PubMed Central

    Shen, Jie-Pan

    2016-01-01

    Morphological plasticity of bacteria is a cryptic phenomenon, by which bacteria acquire adaptive benefits for coping with changing environments. Some environmental cues were identified to induce morphological plasticity, but the underlying molecular mechanisms remain largely unknown. Physical and chemical factors causing morphological changes in bacteria have been investigated and mostly associated with potential pathways linked to the cell wall synthetic machinery. These include starvation, oxidative stresses, predation effectors, antimicrobial agents, temperature stresses, osmotic shock, and mechanical constraints. In an extreme scenario of morphological plasticity, bacteria can be induced to be shapeshifters when the cell walls are defective or deficient. They follow distinct developmental pathways and transform into assorted morphological variants, and most of them would eventually revert to typical cell morphology. It is suggested that phenotypic heterogeneity might play a functional role in the development of morphological diversity and/or plasticity within an isogenic population. Accordingly, phenotypic heterogeneity and inherited morphological plasticity are found to be survival strategies adopted by bacteria in response to environmental stresses. Here, microfluidic and nanofabrication technology is considered to provide versatile solutions to induce morphological plasticity, sort and isolate morphological variants, and perform single-cell analysis including transcriptional and epigenetic profiling. Questions such as how morphogenesis network is modulated or rewired (if epigenetic controls of cell morphogenesis apply) to induce bacterial morphological plasticity could be resolved with the aid of micro-nanofluidic platforms and optimization algorithms, such as feedback system control. PMID:27375812

  17. Plastic debris in the open ocean.

    PubMed

    Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J Ignacio; Irigoien, Xabier; Ubeda, Bárbara; Hernández-León, Santiago; Palma, Alvaro T; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L; Duarte, Carlos M

    2014-07-15

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

  18. GABAergic Inhibition in Visual Cortical Plasticity

    PubMed Central

    Sale, Alessandro; Berardi, Nicoletta; Spolidoro, Maria; Baroncelli, Laura; Maffei, Lamberto

    2010-01-01

    Experience is required for the shaping and refinement of developing neural circuits during well defined periods of early postnatal development called critical periods. Many studies in the visual cortex have shown that intracortical GABAergic circuitry plays a crucial role in defining the time course of the critical period for ocular dominance plasticity. With the end of the critical period, neural plasticity wanes and recovery from the effects of visual defects on visual acuity (amblyopia) or binocularity is much reduced or absent. Recent results pointed out that intracortical inhibition is a fundamental limiting factor for adult cortical plasticity and that its reduction by means of different pharmacological and environmental strategies makes it possible to greatly enhance plasticity in the adult visual cortex, promoting ocular dominance plasticity and recovery from amblyopia. Here we focus on the role of intracortical GABAergic circuitry in controlling both developmental and adult cortical plasticity. We shall also discuss the potential clinical application of these findings to neurological disorders in which synaptic plasticity is compromised because of excessive intracortical inhibition. PMID:20407586

  19. Plastic debris in the open ocean

    PubMed Central

    Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

    2014-01-01

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean. PMID:24982135

  20. Regulatory mechanisms link phenotypic plasticity to evolvability

    PubMed Central

    van Gestel, Jordi; Weissing, Franz J.

    2016-01-01

    Organisms have a remarkable capacity to respond to environmental change. They can either respond directly, by means of phenotypic plasticity, or they can slowly adapt through evolution. Yet, how phenotypic plasticity links to evolutionary adaptability is largely unknown. Current studies of plasticity tend to adopt a phenomenological reaction norm (RN) approach, which neglects the mechanisms underlying plasticity. Focusing on a concrete question – the optimal timing of bacterial sporulation – we here also consider a mechanistic approach, the evolution of a gene regulatory network (GRN) underlying plasticity. Using individual-based simulations, we compare the RN and GRN approach and find a number of striking differences. Most importantly, the GRN model results in a much higher diversity of responsive strategies than the RN model. We show that each of the evolved strategies is pre-adapted to a unique set of unseen environmental conditions. The regulatory mechanisms that control plasticity therefore critically link phenotypic plasticity to the adaptive potential of biological populations. PMID:27087393

  1. Modeling plasticity by non-continuous deformation

    NASA Astrophysics Data System (ADS)

    Ben-Shmuel, Yaron; Altus, Eli

    2017-10-01

    Plasticity and failure theories are still subjects of intense research. Engineering constitutive models on the macroscale which are based on micro characteristics are very much in need. This study is motivated by the observation that continuum assumptions in plasticity in which neighbour material elements are inseparable at all-time are physically impossible, since local detachments, slips and neighbour switching must operate, i.e. non-continuous deformation. Material microstructure is modelled herein by a set of point elements (particles) interacting with their neighbours. Each particle can detach from and/or attach with its neighbours during deformation. Simulations on two- dimensional configurations subjected to uniaxial compression cycle are conducted. Stochastic heterogeneity is controlled by a single "disorder" parameter. It was found that (a) macro response resembles typical elasto-plastic behaviour; (b) plastic energy is proportional to the number of detachments; (c) residual plastic strain is proportional to the number of attachments, and (d) volume is preserved, which is consistent with macro plastic deformation. Rigid body displacements of local groups of elements are also observed. Higher disorder decreases the macro elastic moduli and increases plastic energy. Evolution of anisotropic effects is obtained with no additional parameters.

  2. Predictors of readmission after outpatient plastic surgery.

    PubMed

    Mioton, Lauren M; Buck, Donald W; Rambachan, Aksharananda; Ver Halen, Jon; Dumanian, Gregory A; Kim, John Y S

    2014-01-01

    Hospital readmissions have become a topic of focus for quality care measures and cost-reduction efforts. However, no comparative multi-institutional data on plastic surgery outpatient readmission rates currently exist. The authors endeavored to investigate hospital readmission rates and predictors of readmission following outpatient plastic surgery. The 2011 National Surgical Quality Improvement Program database was reviewed for all outpatient procedures. Unplanned readmission rates were calculated for all 10 tracked surgical specialties (i.e., general, thoracic, vascular, cardiac, orthopedics, otolaryngology, plastics, gynecology, urology, and neurosurgery). Multivariate logistic regression models were used to determine predictors of readmission for plastic surgery. A total of 7005 outpatient plastic surgery procedures were isolated. Outpatient plastic surgery had a low associated readmission rate (1.94 percent) compared with other specialties. Seventy-five patients were readmitted with a complication. Multivariate regression analysis revealed obesity (body mass index ≥ 30), wound infection within 30 days of the index surgery, and American Society of Anesthesiologists class 3 or 4 physical status as significant predictors for unplanned readmission. Unplanned readmission after outpatient plastic surgery is infrequent and compares favorably to rates of readmission among other specialties. Obesity, wound infection within 30 days of the index operation, and American Society of Anesthesiologists class 3 or 4 physical status are independent predictors of readmission. As procedures continue to transition into outpatient settings and the drive to improve patient care persists, these findings will serve to optimize outpatient surgery use.

  3. Cryo-comminution of plastic waste.

    PubMed

    Gente, Vincenzo; La Marca, Floriana; Lucci, Federica; Massacci, Paolo; Pani, Eleonora

    2004-01-01

    Recycling of plastics is a big issue in terms of environmental sustainability and of waste management. The development of proper technologies for plastic recycling is recognised as a priority. To achieve this aim, the technologies applied in mineral processing can be adapted to recycling systems. In particular, the improvement of comminution technologies is one of the main actions to improve the quality of recycled plastics. The aim of this work is to point out suitable comminution processes for different types of plastic waste. Laboratory comminution tests have been carried out under different conditions of temperature and sample pre-conditioning adopting as refrigerant agents CO2 and liquid nitrogen. The temperature has been monitored by thermocouples placed in the milling chamber. Also different internal mill screens have been adopted. A proper procedure has been set up in order to obtain a selective comminution and a size reduction suitable for further separation treatment. Tests have been performed on plastics coming from medical plastic waste and from a plant for spent lead batteries recycling. Results coming from different mill devices have been compared taking into consideration different indexes for representative size distributions. The results of the performed tests show as cryo-comminution improves the effectiveness of size reduction of plastics, promotes liberation of constituents and increases specific surface size of comminuted particles in comparison to a comminution process carried out at room temperature. Copyright 2004 Elsevier Ltd.

  4. Microbial Enzymatic Degradation of Biodegradable Plastics.

    PubMed

    Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

    2017-01-01

    The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. Pregnancy and the Plastic Surgery Resident.

    PubMed

    Garza, Rebecca M; Weston, Jane S; Furnas, Heather J

    2017-01-01

    Combining pregnancy with plastic surgery residency has historically been difficult. Two decades ago, 36 percent of plastic surgery program directors surveyed actively discouraged pregnancy among residents, and 33 percent of women plastic surgeons suffered from infertility. Most alarmingly, 26 percent of plastic surgery trainees had had an elective abortion during residency. With increasing numbers of women training in plastic surgery, this historical lack of support for pregnancy deserves further attention. To explore the current accommodations made for the pregnant plastic surgery resident, an electronic survey was sent to 88 plastic surgery program directors in the United States. Fifty-four responded, for a response rate of 61.36 percent. On average, a director trained a total of 7.91 women among 17.28 residents trained over 8.19 years. Of the women residents, 1.43 were pregnant during a director's tenure, with 1.35 of those residents taking maternity leave. An average 1.75 male residents took paternity leave. Approximately one-third of programs had a formal maternity/paternity leave policy (36.54 percent) which, in most cases, was limited to defining allowed weeks of leave, time required to fulfill program requirements, and remuneration during leave. This survey of plastic surgery directors is a first step in defining the challenges training programs face in supporting the pregnant resident. Directors provided comments describing their challenges accommodating an absent resident in a small program and complying with the American Board of Plastic Surgery's required weeks of training per year. A discussion of these challenges is followed by suggested solutions.

  6. [Application of biodegradable plastic film to reduce plastic film residual pollution in Chinese agriculture].

    PubMed

    Yan, Changrong; He, Wenqing; Xue, Yinghao; Liu, Enke; Liu, Qin

    2016-06-25

    Plastic film has become an important agriculture production material in recent years. Over the past three decades, the amount and application area of plastic film have increased steadily, and in 2014, which are 1.4 million tons and more than 180 million hm² respectively. It plays a key role for ensuring the supply of agricultural goods in China. Meanwhile, plastic film residual pollution becomes more and more serious, and in some regions, the amount of plastic film residues has reached over 250 kg/hm². In part of the Northwest region, soil structure of farmland has been destroyed by plastic film residues and then crop growth and farming operations were suppressed. It is recognized as a good choice to replace plastic film with biodegradable plastic film, an effective measure to solve the plastic film residue pollution. Now, it is in a critical stage of study and assessment of biodegradable plastic film in China and fortunately some biodegradable plastic films show effects in the production of potatoes, peanuts and tobacco. Overall, a series of challenges has still been faced by the biodegradable plastic film, mainly including improving the quality of biodegradable plastic products, such as tensile strength, flexibility, improving the controllability of rupture and degradation, enhancing the ability of increasing soil temperature and preserving soil moisture, and to satisfy the demand of crops production with mulching. In addition, it is essential to reduce the cost of the biodegradable film and promote the application of biodegradable film on large-scale. With the development of biodegradable plastic technology and agricultural production environment, the application of the biodegradable film will have a good future.

  7. Thermal degradation and plasticizing mechanism of poly(vinyl chloride) plasticized with a novel cardanol derived plasticizer

    NASA Astrophysics Data System (ADS)

    Chen, J.; Nie, X. A.; Jiang, J. C.; Zhou, Y. H.

    2018-01-01

    A natural plasticizer cardanol derivatives glycidyl ether (CGE) was synthesized and employed as a plasticizer for the poly(vinyl chloride). The effect of CGE on thermal degradation of PVC films and its plasticizing mechanism were firstly reported. The molecular structure of CGE was characterized with Fourier transform infrared spectroscopy (FTIR). Thermal properties, degradation properties and compatibility of the PVC films were investigated by Differential scanning calorimeter analysis (DSC), Thermogravimetric analysis (TGA) and FTIR, respectively. Compared with the commercial plasticizers dioctylphthalate (DOP), CGE can endow PVC film with a decrease of 4.31 °C in glass transition temperature (Tg), an increase of 24.01 °C and 25.53 °C in 10% weight loss (T 10) and 50% weight loss (T 50) respectively, and a higher activetion energy of thermal degradation (Ea ).

  8. Epigenetics and Developmental Plasticity Across Species

    PubMed Central

    Champagne, Frances A.

    2012-01-01

    Plasticity is a typical feature of development and can lead to divergent phenotypes. There is increasing evidence that epigenetic mechanisms, such as DNA methylation, are present across species, are modifiable by the environment, and are involved in developmental plasticity. Thus, in the context of the concept of developmental homology, epigenetic mechanisms may serve to create a process homology between species by providing a common molecular pathway through which environmental experiences shape development, ultimately leading to phenotypic diversity. This article will highlight evidence derived from across-species investigations of epigenetics, development, and plasticity which may contribute to our understanding of the homology that exists between species and between ancestors and descendants. PMID:22711291

  9. Plasticity in single neuron and circuit computations

    NASA Astrophysics Data System (ADS)

    Destexhe, Alain; Marder, Eve

    2004-10-01

    Plasticity in neural circuits can result from alterations in synaptic strength or connectivity, as well as from changes in the excitability of the neurons themselves. To better understand the role of plasticity in the brain, we need to establish how brain circuits work and the kinds of computations that different circuit structures achieve. By linking theoretical and experimental studies, we are beginning to reveal the consequences of plasticity mechanisms for network dynamics, in both simple invertebrate circuits and the complex circuits of mammalian cerebral cortex.

  10. Optical sensors based on plastic fibers.

    PubMed

    Bilro, Lúcia; Alberto, Nélia; Pinto, João L; Nogueira, Rogério

    2012-01-01

    The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

  11. Electroless shielding of plastic electronic enclosures

    NASA Astrophysics Data System (ADS)

    Thompson, D.

    1985-12-01

    The containment or exclusion of radio frequency interference (RFI) via metallized plastic enclosures and the electroless plating as a solution are examined. The electroless coating and process, shielding principles and test data, shielding design requirements, and shielding advantages and limitations are reviewed. It is found that electroless shielding provides high shielding effectiveness to plastic substrates. After application of a conductive metallic coating by electroless plating, various plastics have passed the ASTM adhesion test after thermal cycle and severe environmental testing. Electroless shielding provides a lightweight, totally metallized housing to EMI/RFI shielding. Various compositions of electroless deposits are found to optimize electroless shielding cost/benefit ratio.

  12. Consciousness: the radical plasticity thesis.

    PubMed

    Cleeremans, Axel

    2008-01-01

    In this chapter, I sketch a conceptual framework which takes it as a starting point that conscious and unconscious cognition are rooted in the same set of interacting learning mechanisms and representational systems. On this view, the extent to which a representation is conscious depends in a graded manner on properties such as its stability in time or its strength. Crucially, these properties are accrued as a result of learning, which is in turn viewed as a mandatory process that always accompanies information processing. From this perspective, consciousness is best characterized as involving (1) a graded continuum defined over "quality of representation", such that availability to consciousness and to cognitive control correlates with quality, and (2) the implication of systems of metarepresentations. A first implication of these ideas is that the main function of consciousness is to make flexible, adaptive control over behavior possible. A second, much more speculative implication, is that we learn to be conscious. This I call the "radical plasticity thesis"--the hypothesis that consciousness emerges in systems capable not only of learning about their environment, but also about their own internal representations of it.

  13. Working memory plasticity and aging.

    PubMed

    Rhodes, Rebecca E; Katz, Benjamin

    2017-02-01

    The present research explores how the trajectory of learning on a working memory task changes throughout the life span, and whether gains in working memory performance are exclusively a question of initial working memory capacity (WMC) or whether age exerts an independent effect. In a large, cross-sectional study of younger, middle-aged, and older adults, we examined learning on a widely used working memory task-the dual n-back task-over 20 sessions of practice. We found that, while all age groups improved on the task, older adults demonstrated less improvement on the task, and also reached a lower asymptotic maximum performance than younger adults. After controlling for initial WMC, we found that age exerted independent effects on training gains and asymptotic performance; older adults tended to improve less and reached lower levels of performance than younger adults. The difference between younger and older adults' rates of learning depended in part on initial WMC. These results suggest that age-related effects on working memory include not only effects on capacity, but also plasticity and the ability to improve on a task. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. Distortion-free foamed-plastic parts

    NASA Technical Reports Server (NTRS)

    Hogenson, P. A.; Jackson, R. G.

    1979-01-01

    In process for molding foamed-plastic products, gases that are formed as byproducts of foaming reaction escape through perforated die. Thus, volatiles are not trapped in pockets that can deform and weaken the molded part.

  15. Methane Detector With Plastic Fresnel Lens

    NASA Technical Reports Server (NTRS)

    Grant, W. B.

    1986-01-01

    Laser detector for natural gas leaks modified by substitution of molded plastic lens for spherical mirror. By measuring relative attenuation at two wavelengths, detector used to check for methane escaping from pipelines above or below ground and from landfill.

  16. Construction loads experienced by plastic composite ties.

    DOT National Transportation Integrated Search

    2014-07-01

    Damage to plastic composite ties during handling and track installation has been reported by a number of railroads. Results from : a survey conducted to identify specific handling issues were used to develop field and laboratory tests to measure the ...

  17. Vapor pressure measured with inflatable plastic bag

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.

  18. Viscoelasticity and plasticity mechanisms of human dentin

    NASA Astrophysics Data System (ADS)

    Borodin, E. N.; Seyedkavoosi, S.; Zaitsev, D.; Drach, B.; Mikaelyan, K. N.; Panfilov, P. E.; Gutkin, M. Yu.; Sevostianov, I.

    2018-01-01

    Theoretical models of viscoelastic behavior and plastic deformation mechanisms of human dentin are considered. Using the linear viscoelasticity theory in which creep and relaxation kernels have the form of fraction-exponential functions, numerical values of instantaneous and long-time Young's moduli and other characteristics of dentin viscoelasticity under uniaxial compression are found. As dentin plastic deformation mechanisms, mutual collagen fiber sliding in the region of contact of their side surfaces, separation of these fibers from each other, and irreversible tension of some collagen fibers, are proposed. It is shown that the second mechanism activation requires a smaller stress than that for activating others. The models of plastic zones at the mode I crack tip, which correspond to these mechanisms, are studied. It is shown that the plastic zone size can increase from a few hundreds of nanometers to hundreds of micrometers with increasing applied stress.

  19. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, C.S.; Reed, S.T.

    1988-01-26

    An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  20. Sol-gel antireflective coating on plastics

    DOEpatents

    Ashley, Carol S.; Reed, Scott T.

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  1. Rotating mandrel speeds assembly of plastic inflatables

    NASA Technical Reports Server (NTRS)

    Mac Fadden, J. A.; Stenlund, S. J.; Wendt, A. J.

    1966-01-01

    Rotating mandrel permits the accurate cutting, forming, and sealing of plastic gores for assembly of an inflatable surface of revolution. The gores remain on the mandrel until the final seam is reached. Tolerances are tightly controlled by the mandrel configuration.

  2. REDUCING EMISSIONS IN FIBERGLASS REINFORCED PLASTICS MANUFACTURING

    EPA Science Inventory

    The paper summarizes results of an evaluation of pollution prevention techniques, so that technical assistance providers can provide better information to fiber-reinforced plastics and composites (FRP/C) facilities about pollution prevention options. It gives background about the...

  3. Plastics and Rubber Products Manufacturing (NAICS 326)

    EPA Pesticide Factsheets

    Find environmental regulatory and compliance information for plastics and rubber products manufacturing (which includes the manufacture of cellulose and other fibers) including information about NESHAPs and effluent guidelines for wastewater discharges

  4. Elastic And Plastic Deformations In Butt Welds

    NASA Technical Reports Server (NTRS)

    Verderaime, V.

    1992-01-01

    Report presents study of mathematical modeling of stresses and strains, reaching beyond limits of elasticity, in bars and plates. Study oriented toward development of capability to predict stresses and resulting elastic and plastic strains in butt welds.

  5. Scale effects in crystal plasticity

    NASA Astrophysics Data System (ADS)

    Padubidri Janardhanachar, Guruprasad

    The goal of this research work is to further the understanding of crystal plasticity, particularly at reduced structural and material length scales. Fundamental understanding of plasticity is central to various challenges facing design and manufacturing of materials for structural and electronic device applications. The development of microstructurally tailored advanced metallic materials with enhanced mechanical properties that can withstand extremes in stress, strain, and temperature, will aid in increasing the efficiency of power generating systems by allowing them to work at higher temperatures and pressures. High specific strength materials can lead to low fuel consumption in transport vehicles. Experiments have shown that enhanced mechanical properties can be obtained in materials by constraining their size, microstructure (e.g. grain size), or both for various applications. For the successful design of these materials, it is necessary to have a thorough understanding of the influence of different length scales and evolving microstructure on the overall behavior. In this study, distinction is made between the effect of structural and material length scale on the mechanical behavior of materials. A length scale associated with an underlying physical mechanism influencing the mechanical behavior can overlap with either structural length scales or material length scales. If it overlaps with structural length scales, then the material is said to be dimensionally constrained. On the other hand, if it overlaps with material length scales, for example grain size, then the material is said to be microstructurally constrained. The objectives of this research work are: (1) to investigate scale and size effects due to dimensional constraints; (2) to investigate size effects due to microstructural constraints; and (3) to develop a size dependent hardening model through coarse graining of dislocation dynamics. A discrete dislocation dynamics (DDD) framework where the

  6. Molding apparatus. [for thermosetting plastic compositions

    NASA Technical Reports Server (NTRS)

    Heier, W. C. (Inventor)

    1974-01-01

    Apparatus for compression molding of thermosetting plastics compositions including interfitting hollow male and female components is reported. The components are adapted to be compressed to form a rocket nozzle in a cavity. A thermal jacket is provided exteriorly adjacent to the female component for circulating a thermal transfer fluid to effect curing of a thermosetting plastics material being molded. Each of the male and female components is provided with suitable inlets and outlets for circulating a thermal transfer fluid.

  7. Recovery of monomers from recycled plastics

    SciTech Connect

    Sharp, L.L.; Ness, R.O. Jr.; Sosa, J.M.

    1995-10-01

    Plastics make up approximately 20% by volume of the material disposed of in landfills in the United States. The increased interest in recycling has focused attention on ways to expand our current recycling efforts. Types of commodity plastics typically found in a postconsumer stream include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (PS). In addition to plastics such as these, a number of organic and inorganic constituents will be present, including paper, paint, food, and various metals. These constituents are present as a result of introduction intomore » the plastics during manufacturing (to give a plastic product selective properties) or as residual matter from use by the consumer. The Energy & Environmental Research Center (EERC) is one of several groups in the United States and Europe that, over the last several years, has worked toward developing a process to thermally break down postconsumer plastics to hydrocarbon liquids and gases. Such a process, sometimes referred to as thermal depolymerization, thermal recycling, or feedstock recycling, produces hydrocarbon liquids and gases that could be used for the manufacture of new plastics or other petroleum products. The specific slate of products depends on processing conditions. Subsequent studies have identified several relatively high-value products possible from the process, including ethylene (C{sub 2}{sup -}), propylene (C{sub 3}{sup -}), and butylenes. Past work at the EERC has also indicated that optimal processing conditions exist for these olefin yields. The proposed the EPA work is based on information, presented here, that was obtained in studies completed at the EERC under the sponsorship of the American Plastics Council (APC) and the U.S. Department of Energy (DOE).« less

  8. Localized coating removal using plastic media blasting

    NASA Technical Reports Server (NTRS)

    Novak, Howard L.; Wyckoff, Michael G.; Zook, Lee M.

    1988-01-01

    Steps taken to qualify the use of plastic media blasting for safely and effectively removing paint and other coatings from solid rocket booster aluminum structures are described. As a result of the effort, an improvement was made in the design of surface finishing equipment for processing flight hardware, in addition to a potentially patentable idea on improved plastic media composition. The general arrangement of the blast equipment and the nozzle configuration are presented.

  9. Plastic, Fantastic? What We Make. Science and Technology Education in Philippine Society.

    ERIC Educational Resources Information Center

    Philippines Univ., Quezon City. Inst. for Science and Mathematics Education Development.

    This module provides information about plastics, focusing on the uses of plastic bags in particular. Topic areas considered include: (1) making plastic bags; (2) transparency of plastic bags; (3) plastic bags and food odors; (4) food containers (before and since plastics); and (5) disposing of plastic bags and other plastic products. The text is…

  10. Education on the Business of Plastic Surgery During Training: A Survey of Plastic Surgery Residents.

    PubMed

    Ovadia, Steven A; Gishen, Kriya; Desai, Urmen; Garcia, Alejandro M; Thaller, Seth R

    2018-06-01

    Entrepreneurial skills are important for physicians, especially plastic surgeons. Nevertheless, these skills are not typically emphasized during residency training. Evaluate the extent of business training at plastic surgery residency programs as well as means of enhancing business training. A 6-question online survey was sent to plastic surgery program directors for distribution to plastic surgery residents. Responses from residents at the PGY2 level and above were included for analysis. Tables were prepared to present survey results. Hundred and sixty-six residents including 147 PGY2 and above residents responded to our survey. Only 43.5% reported inclusion of business training in their plastic surgery residency. A majority of residents reported they do not expect on graduation to be prepared for the business aspects of plastic surgery. Additionally, a majority of residents feel establishment of a formal lecture series on the business of plastic surgery would be beneficial. Results from our survey indicate limited training at plastic surgery programs in necessary business skills. Plastic surgery residency programs should consider incorporating or enhancing elements of business training in their curriculum. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  11. Combustion and Gasification Properties of Plastics Particles.

    PubMed

    Zevenhoven, Ron; Karlsson, Magnus; Hupa, Mikko; Frankenhaeuser, Martin

    1997-08-01

    The combustion and gasification behavior of the most common plastics is studied and compared with conventional fuels such as coal, peat, and wood. The aim is to give background data for finding the optimum conditions for co-combustion or co-gasification of a conventional fuel with a certain amount of plastic-derived fuel. Atmospheric or pressurized fluidized bed co-combustion of conventional fuels and plastics are considered to be promising future options. The plastics investigated were poly(ethylene) (PE), poly(propylene) (PP), poly(styrene) (PS), and poly(vinyl chloride) (PVC). Some of the samples had a print or color. The reference fuels were Polish bituminous coal, Finnish peat, and Finnish pine wood. PE, PP, and PS were found to burn like oil. The particles shrank to a droplet and burned completely during the pyrolysis stage, leaving no char. Printing and coloring left a small portion of ash. PVC was the only plastic that produced a carbonaceous residue, and its timescales for heating, devolatilization, and char burning were of the same order as those for peat and wood, and much shorter for the other plastics studied. An important result is that char from PVC contains less than 1% chlorine,99% hydrocarbon. The gasification rate of PVC char (at 1 bar and 25 bar) was of the same order as that of char from coal. Peat-char and wood-char were gasified an order of magnitude faster.

  12. Pathogen evolution under host avoidance plasticity.

    PubMed

    McLeod, David V; Day, Troy

    2015-09-07

    Host resistance consists of defences that limit pathogen burden, and can be classified as either adaptations targeting recovery from infection or those focused upon infection avoidance. Conventional theory treats avoidance as a fixed strategy which does not vary from one interaction to the next. However, there is increasing empirical evidence that many avoidance strategies are triggered by external stimuli, and thus should be treated as phenotypically plastic responses. Here, we consider the implications of avoidance plasticity for host-pathogen coevolution. We uncover a number of predictions challenging current theory. First, in the absence of pathogen trade-offs, plasticity can restrain pathogen evolution; moreover, the pathogen exploits conditions in which the host would otherwise invest less in resistance, causing resistance escalation. Second, when transmission trades off with pathogen-induced mortality, plasticity encourages avirulence, resulting in a superior fitness outcome for both host and pathogen. Third, plasticity ensures the sterilizing effect of pathogens has consequences for pathogen evolution. When pathogens castrate hosts, selection forces them to minimize mortality virulence; moreover, when transmission trades off with sterility alone, resistance plasticity is sufficient to prevent pathogens from evolving to fully castrate. © 2015 The Author(s).

  13. Changing trends in plastic surgery training.

    PubMed

    Sharma, Ramesh Kumar

    2014-05-01

    The currently available training models are being put to scrutiny in India today, both by the residents and the teachers. Plastic surgery specialty was created primarily for reconstructive purposes but the society always perceived it from a cosmetic angle, particularly in the post second world war era. As a result, there is a need to redefine the goals of plastic surgery training in the present times so that the plastic surgeon is "future ready" to meet the needs of society and the market forces. The author has reviewed the currently available literature on plastic surgery training from India and the western countries. An attempt has been made to study opinions from the teachers and the trainees. The modules currently available in India and abroad have been analyzed and a suggestion has been made for drafting training programs that would meet the demands of the society as well as prepare the resident both for the aesthetic and reconstructive practice. The plastic surgery training needs to be more vibrant and in tune with the changing times. While maintaining its core nature, the current predominantly reconstructive modules need to incorporate the aesthetic content. The evaluation should be both knowledge and competence based. The teachers need to be educated in the various teaching methods that are more applicable to grown up residents. There is a need to find ways to attract talented people in the academic plastic surgery.

  14. Plastic photochromic eyewear: a status report

    NASA Astrophysics Data System (ADS)

    Crano, John C.; Elias, Richard C.

    1991-12-01

    An estimated 10 million pairs of photochromic prescription lenses were dispensed in the United States in 1989, essentially all based on a silver halide system suspended in an inorganic glass. A significant trend within the ophthalmic industry has been the growth of light-weight plastic lenses. In the United States market, the percentage of prescription eyewear made of plastic is now greater than 70%. With this increasing market penetration of plastic lenses, the desire for an acceptable plastic photochromic lens has also increased. As with any commercial product, in order to achieve consumer acceptance there exist several technical requirements for a plastic photochromic lens. These include the light transmission and color of the lens in both the unactivated and activated states, the speeds of darkening and fading, and the fatigue resistance or lifetime of the photochromic system. These requirements will be defined along with approaches to achieving them. The properties of the commercially available plastic photochromic lenses will be compared with the defined requirements.

  15. Changing trends in plastic surgery training

    PubMed Central

    Sharma, Ramesh Kumar

    2014-01-01

    Background: The currently available training models are being put to scrutiny in India today, both by the residents and the teachers. Plastic surgery specialty was created primarily for reconstructive purposes but the society always perceived it from a cosmetic angle, particularly in the post second world war era. As a result, there is a need to redefine the goals of plastic surgery training in the present times so that the plastic surgeon is “future ready” to meet the needs of society and the market forces. Materials and Methods: The author has reviewed the currently available literature on plastic surgery training from India and the western countries. An attempt has been made to study opinions from the teachers and the trainees. The modules currently available in India and abroad have been analyzed and a suggestion has been made for drafting training programs that would meet the demands of the society as well as prepare the resident both for the aesthetic and reconstructive practice. Conclusions: The plastic surgery training needs to be more vibrant and in tune with the changing times. While maintaining its core nature, the current predominantly reconstructive modules need to incorporate the aesthetic content. The evaluation should be both knowledge and competence based. The teachers need to be educated in the various teaching methods that are more applicable to grown up residents. There is a need to find ways to attract talented people in the academic plastic surgery. PMID:25190909

  16. Consumer Exposure to Bisphenol A from Plastic Bottles

    ERIC Educational Resources Information Center

    Bidabadi, Fatemeh

    2013-01-01

    Bisphenol A (BPA) is a plastic monomer and plasticizer and is a chemical that has one of the highest volume production worldwide, with more than six billion pounds each year. Its primary use is the production of polycarbonate plastics, epoxy resins used to line metal cans in a host of plastic consumer products such as toys, water pipes, drinking…

  17. 49 CFR 192.321 - Installation of plastic pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

  18. 49 CFR 192.193 - Valve installation in plastic pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  19. 49 CFR 178.517 - Standards for plastic boxes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for plastic boxes. 178.517 Section 178...-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

  20. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are as...

  1. 33 CFR 183.552 - Plastic encased fuel tanks: Installation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Plastic encased fuel tanks... § 183.552 Plastic encased fuel tanks: Installation. (a) Each fuel tank encased in cellular plastic foam or in fiber reinforced plastic must have the connections, fittings, and labels accessible for...

  2. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  3. 49 CFR 192.375 - Service lines: Plastic.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

  4. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for plastic film bags. 178.519 Section... PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film...

  5. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

  6. Plasticity: A New Materialist Approach to Policy and Methodology

    ERIC Educational Resources Information Center

    Ulmer, Jasmine B.

    2015-01-01

    This article examines Catherine Malabou's philosophical concept of plasticity as a new materialist methodology. Given that plasticity simultaneously maintains the ability to receive, give, and annihilate form, plasticity and plastic readings offer material-discursive possibilities for educational research. This article begins by discussing the…

  7. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended to...

  8. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended to...

  9. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended to...

  10. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended to...

  11. 49 CFR 178.517 - Standards for plastic boxes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for plastic boxes. 178.517 Section 178... PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

  12. 49 CFR 192.193 - Valve installation in plastic pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  13. 49 CFR 192.191 - Design pressure of plastic fittings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Design pressure of plastic fittings. 192.191... Components § 192.191 Design pressure of plastic fittings. (a) Thermosetting fittings for plastic pipe must conform to ASTM D 2517, (incorporated by reference, see § 192.7). (b) Thermoplastic fittings for plastic...

  14. 33 CFR 183.552 - Plastic encased fuel tanks: Installation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Plastic encased fuel tanks... § 183.552 Plastic encased fuel tanks: Installation. (a) Each fuel tank encased in cellular plastic foam or in fiber reinforced plastic must have the connections, fittings, and labels accessible for...

  15. 49 CFR 192.321 - Installation of plastic pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

  16. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

  17. 49 CFR 192.375 - Service lines: Plastic.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

  18. 21 CFR 878.3925 - Plastic surgery kit and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Plastic surgery kit and accessories. 878.3925... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Prosthetic Devices § 878.3925 Plastic surgery kit and accessories. (a) Identification. A plastic surgery kit and accessories is a device intended to...

  19. 33 CFR 183.552 - Plastic encased fuel tanks: Installation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Plastic encased fuel tanks... § 183.552 Plastic encased fuel tanks: Installation. (a) Each fuel tank encased in cellular plastic foam or in fiber reinforced plastic must have the connections, fittings, and labels accessible for...

  20. 49 CFR 192.193 - Valve installation in plastic pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  1. 49 CFR 192.193 - Valve installation in plastic pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  2. 49 CFR 178.517 - Standards for plastic boxes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for plastic boxes. 178.517 Section 178...-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

  3. 49 CFR 192.191 - Design pressure of plastic fittings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Design pressure of plastic fittings. 192.191... Components § 192.191 Design pressure of plastic fittings. (a) Thermosetting fittings for plastic pipe must conform to ASTM D 2517, (incorporated by reference, see § 192.7). (b) Thermoplastic fittings for plastic...

  4. 49 CFR 192.321 - Installation of plastic pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

  5. 49 CFR 178.517 - Standards for plastic boxes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for plastic boxes. 178.517 Section 178...-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

  6. 49 CFR 192.375 - Service lines: Plastic.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

  7. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  8. 49 CFR 192.375 - Service lines: Plastic.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

  9. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are as...

  10. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  11. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

  12. 49 CFR 192.321 - Installation of plastic pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

  13. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

  14. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  15. 33 CFR 183.552 - Plastic encased fuel tanks: Installation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Plastic encased fuel tanks... § 183.552 Plastic encased fuel tanks: Installation. (a) Each fuel tank encased in cellular plastic foam or in fiber reinforced plastic must have the connections, fittings, and labels accessible for...

  16. 49 CFR 178.517 - Standards for plastic boxes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for plastic boxes. 178.517 Section 178...-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

  17. 49 CFR 192.193 - Valve installation in plastic pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  18. 33 CFR 183.552 - Plastic encased fuel tanks: Installation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Plastic encased fuel tanks... § 183.552 Plastic encased fuel tanks: Installation. (a) Each fuel tank encased in cellular plastic foam or in fiber reinforced plastic must have the connections, fittings, and labels accessible for...

  19. 49 CFR 192.375 - Service lines: Plastic.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

  20. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are as...

  1. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

  2. 49 CFR 192.321 - Installation of plastic pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

  3. 49 CFR 192.191 - Design pressure of plastic fittings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Design pressure of plastic fittings. 192.191... Components § 192.191 Design pressure of plastic fittings. (a) Thermosetting fittings for plastic pipe must conform to ASTM D 2517, (incorporated by reference, see § 192.7). (b) Thermoplastic fittings for plastic...

  4. 49 CFR 178.519 - Standards for plastic film bags.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for plastic film bags. 178.519 Section...-bulk Performance-Oriented Packaging Standards § 178.519 Standards for plastic film bags. (a) The identification code for a plastic film bag is 5H4. (b) Construction requirements for plastic film bags are as...

  5. Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

    NASA Astrophysics Data System (ADS)

    Galeano, D. C.; Cavalcante, F. R.; Carvalho, A. B.; Hunt, J.

    2014-02-01

    The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature.

  6. Comparison of pediatric radiation dose and vessel visibility on angiographic systems using piglets as a surrogate: antiscatter grid removal vs. lower detector air kerma settings with a grid — a preclinical investigation

    PubMed Central

    Racadio, John M.; Abruzzo, Todd A.; Johnson, Neil D.; Patel, Manish N.; Kukreja, Kamlesh U.; den Hartog, Mark. J. H.; Hoornaert, Bart P.A.; Nachabe, Rami A.

    2015-01-01

    The purpose of this study was to reduce pediatric doses while maintaining or improving image quality scores without removing the grid from X‐ray beam. This study was approved by the Institutional Animal Care and Use Committee. Three piglets (5, 14, and 20 kg) were imaged using six different selectable detector air kerma (Kair) per frame values (100%, 70%, 50%, 35%, 25%, 17.5%) with and without the grid. Number of distal branches visualized with diagnostic confidence relative to the injected vessel defined image quality score. Five pediatric interventional radiologists evaluated all images. Image quality score and piglet Kair were statistically compared using analysis of variance and receiver operating curve analysis to define the preferred dose setting and use of grid for a visibility of 2nd and 3rd order vessel branches. Grid removal reduced both dose to subject and imaging quality by 26%. Third order branches could only be visualized with the grid present; 100% detector Kair was required for smallest pig, while 70% detector Kair was adequate for the two larger pigs. Second order branches could be visualized with grid at 17.5% detector Kair for all three pig sizes. Without the grid, 50%, 35%, and 35% detector Kair were required for smallest to largest pig, respectively. Grid removal reduces both dose and image quality score. Image quality scores can be maintained with less dose to subject with the grid in the beam as opposed to removed. Smaller anatomy requires more dose to the detector to achieve the same image quality score. PACS numbers: 87.53.Bn, 87.57.N‐, 87.57.cj, 87.59.cf, 87.59.Dj PMID:26699297

  7. The Prevalence of Cosmetic Facial Plastic Procedures among Facial Plastic Surgeons.

    PubMed

    Moayer, Roxana; Sand, Jordan P; Han, Albert; Nabili, Vishad; Keller, Gregory S

    2018-04-01

    This is the first study to report on the prevalence of cosmetic facial plastic surgery use among facial plastic surgeons. The aim of this study is to determine the frequency with which facial plastic surgeons have cosmetic procedures themselves. A secondary aim is to determine whether trends in usage of cosmetic facial procedures among facial plastic surgeons are similar to that of nonsurgeons. The study design was an anonymous, five-question, Internet survey distributed via email set in a single academic institution. Board-certified members of the American Academy of Facial Plastic and Reconstructive Surgery (AAFPRS) were included in this study. Self-reported history of cosmetic facial plastic surgery or minimally invasive procedures were recorded. The survey also queried participants for demographic data. A total of 216 members of the AAFPRS responded to the questionnaire. Ninety percent of respondents were male ( n  = 192) and 10.3% were female ( n  = 22). Thirty-three percent of respondents were aged 31 to 40 years ( n  = 70), 25% were aged 41 to 50 years ( n  = 53), 21.4% were aged 51 to 60 years ( n  = 46), and 20.5% were older than 60 years ( n  = 44). Thirty-six percent of respondents had a surgical cosmetic facial procedure and 75% has at least one minimally invasive cosmetic facial procedure. Facial plastic surgeons are frequent users of cosmetic facial plastic surgery. This finding may be due to access, knowledge base, values, or attitudes. By better understanding surgeon attitudes toward facial plastic surgery, we can improve communication with patients and delivery of care. This study is a first step in understanding use of facial plastic procedures among facial plastic surgeons. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  8. Synthesis of biodegradable plastic from tapioca with N-Isopropylacrylamid and chitosan using glycerol as plasticizer

    NASA Astrophysics Data System (ADS)

    Syaubari; Safwani, S.; Riza, M.

    2018-04-01

    One of natural polymers that can be used as raw material in the manufacture of biodegradable plastic is tapioca and chitosan. The addition of other compounds such as glycerol as plasticizer is to improve the characteristics of the plastic that already produced. N- Isopropylacrylamid (NIPAm) is an organic compound that can be synthesized into a polymer or polymer grafting which also biodegradable too. This research aims tostudy the synthesis of biodegradable plastics from tapioca with the addition of chitosan, NIPAm, poly(NIPAm) and analyze the characteristics of biodegradable plastics that already produced. This research was done in three stages, there are (1) polymerization NIPAm, (2) the grafting of chitosan-poly NIPAm and (3) the synthesis of biodegradable plastics from starch mixture with variation of addition chitosan, NIPAm, poly(NIPAm), chitosan-graft-poly(NIPAm) and also variations of glycerol as plasticizer. The results of this research is a thin sheet of plastic which is will get analyzed for the characteristics of functional groups, mechanical, morphological and its biodegradability. FTIR spectra showed the grafting process with the new group formation of CO single-bond at 850 cm-1. Plastic with the addition of NIPAm and 1 ml glycerol has the highest tensile strength value about 31.1 MPa. Plastic with poly(NIPAm) and 4 ml glycerol produces the highest elongation value about 153.72%. Plastic with Chitosan-graft-poly(NIPAm) with 1 ml glycerol has the longest biodegradation because of the small mass-loss for six weeks which is about 6.6%.

  9. Crystal plastic earthquakes in dolostones

    NASA Astrophysics Data System (ADS)

    Passelegue, Francois; Aubry, Jerome; Nicolas, Aurelien; Fondriest, Michele; Schubnel, Alexandre; Di Toro, Giulio

    2017-04-01

    processes. We demonstrate that the transition from slow to dynamic instabilities is observed when the entire fault exhibits plastic processes, which increase the stiffness of the fault.

  10. [Preliminary evaluation of plastic crown restoration supported by osseointegrated implants].

    PubMed

    Huang, J; Zhang, K

    1997-08-01

    This study was to evaluate the feasibility of plastic crown restoration supported by osseointegrated implants. The following conclusions were drawn from this study: plastic crown gave better biomechanical consideration than porcelain fused to metal (PFM) crown in osseointegrated prostheses, but plastic crown gave worse wearability, tensile strength, compression strength and flexuaral strength than PFM crown. After restoration the disadvantages of the plastic crown were beyond the clinical acceptable range. It showed plastic crown designed dental prothetic implantation was unfeasible.

  11. Aesthetic breast shape preferences among plastic surgeons.

    PubMed

    Broer, Peter Niclas; Juran, Sabrina; Walker, Marc E; Ng, Reuben; Weichman, Katie; Tanna, Neil; Liu, Yuen-Jong; Shah, Ajul; Patel, Anup; Persing, John A; Thomson, James Grant

    2015-06-01

    There has been little discussion in the plastic surgery literature regarding breast shape preferences among plastic surgeons, despite strong evidence that such aesthetic preferences are influenced by multiple factors. Much effort has been focused on delineating the objective criteria by which an "attractive" breast might be defined. This study aimed at providing a better understanding of the presence and significance of differences in personal aesthetic perception, and how these relate to a plastic surgeon's demographic, ethnic, and cultural background, as well as practice type (academic vs private). An interactive online survey was designed. Modifiable ranges of upper pole fullness and areola size were achieved via digital alteration, enabling participants to interactively change the shape of a model's breasts. The questionnaire was translated into multiple languages and sent to plastic surgeons worldwide. Demographic data were also collected. Analysis of variance was used to elucidate plastic surgeon's breast shape preferences in respect to sex and age, geographic and ethnic background, as well as practice type. The authors gathered 614 responses from 29 different countries. Significant differences regarding preferences for upper pole fullness, areola size in the natural breast, and areola size in the augmented breast were identified across surgeons from the different countries. Further, significant relationships regarding breast shape preferences were distilled between the age and sex of the surgeon, as well as the practice type. No differences were found in respect to the surgeons' self-reported ethnic background. Country of residence, age, and practice type significantly impact breast shape preferences of plastic surgeons. These findings have implications for both patients seeking and surgeons performing cosmetic and reconstructive breast surgery. In an increasingly global environment, cultural differences and international variability must be considered when

  12. Social Media and the Plastic Surgery Patient.

    PubMed

    Sorice, Sarah C; Li, Alexander Y; Gilstrap, Jarom; Canales, Francisco L; Furnas, Heather J

    2017-11-01

    Many plastic surgeons use social media as a marketing tool to attract and retain patients, but information about how patients use social media and their preferred types of plastic surgery posts have been lacking. To investigate patients' preferred social media networks and the type of posts they wished to see, a cross-sectional study was conducted in a single aesthetic practice of two plastic surgeons by surveying 100 consecutive patients. The age of the patients averaged 44.4 years (range, 17 to 78 years). Facebook had the greatest patient use and engagement, with YouTube second in use, and Instagram second in number of engaged users. Over half used Pinterest, but with little daily engagement. Only one-fourth used Snapchat, but the percentage of users who were highly engaged was second only to Facebook. The least popular network was Twitter, with the fewest patient users and least engagement. Social media played a minor role compared with the practice's Web site in both influencing patients to choose the practice and providing information on the day of the appointment. Patients most wanted to see posts on a plastic surgeon's social media platform related to practice information, before-and-after photographs, and contests. Articles about plastic surgery held the least interest. Among five types of Web site content, patients expressed most interest in before-and-after photographs. This study is the first to articulate the plastic surgery patient perspective regarding social media. The findings aim to help plastic surgeons maximize their influence on their target audience.

  13. Practical solution of plastic deformation problems in elastic-plastic range

    NASA Technical Reports Server (NTRS)

    Mendelson, A; Manson, S

    1957-01-01

    A practical method for solving plastic deformation problems in the elastic-plastic range is presented. The method is one of successive approximations and is illustrated by four examples which include a flat plate with temperature distribution across the width, a thin shell with axial temperature distribution, a solid cylinder with radial temperature distribution, and a rotating disk with radial temperature distribution.

  14. 75 FR 34170 - Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ... Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC, Troy, MI... the Anderson, South Carolina location of Plastic Omnium Automotive Exteriors, LLC, working out of Troy... certification to include workers in support of the Anderson, South Carolina facility working out of Troy...

  15. Preparing Attitude Scale to Define Students' Attitudes about Environment, Recycling, Plastic and Plastic Waste

    ERIC Educational Resources Information Center

    Avan, Cagri; Aydinli, Bahattin; Bakar, Fatma; Alboga, Yunus

    2011-01-01

    The aim of this study is to introduce an attitude scale in order to define students? attitudes about environment, recycling, plastics, plastic waste. In this study, 80 attitude sentences according to 5-point Likert-type scale were prepared and applied to 492 students of 6th grade in the Kastamonu city center of Turkey. The scale consists of…

  16. Preparation and properties of water and glycerol-plasticized sugar beet pulp plastics

    USDA-ARS?s Scientific Manuscript database

    Sugar beet pulp (SBP), the residue from sugar extraction, was compounded and turned into thermoplastic composite materials. The compounding was performed using a common twin screw compounding extruder and water and glycerol were used as plasticizers. The plasticization of SBP utilized the water-solu...

  17. Degradation of Oxo-Biodegradable Plastic by Pleurotus ostreatus

    PubMed Central

    da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Nunes, Mateus Dias; da Silva, Marliane de Cássia Soares; Kasuya, Maria Catarina Megumi

    2013-01-01

    Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate. PMID:23967057

  18. Degradation of oxo-biodegradable plastic by Pleurotus ostreatus.

    PubMed

    da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Nunes, Mateus Dias; da Silva, Marliane de Cássia Soares; Kasuya, Maria Catarina Megumi

    2013-01-01

    Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate.

  19. SU-F-T-09: In Phantom Full-Implant Validation of Plastic Scintillation Detectors for in Vivo Dosimetry During Low Dose Rate Brachytherapy

    SciTech Connect

    Therriault-Proulx, F; Bruno, T; Beddar, S

    Purpose: To validate in a water phantom the use of plastic scintillation detectors to measure dose to the urethra and the rectal wall during a clinically realistic low dose rate (LDR) brachytherapy implant. Methods: A template was designed to replicate a clinically realistic LDR brachytherapy prostate implant inside a water phantom. Twenty-two catheters were inserted, including one mimicking the urethra and another the rectal wall. The needles inserted in the remaining 20 catheters were composed of thin-walled nylon tubes in which I-125 radioactive seeds (Air Kerma Strengths of (0.328±0.020)U) were abutted together with plastic spacers to replicate a typical loading.more » A plastic scintillation detector (PSD) with a 5-mm long × 1-mm diameter sensitive element was first placed inside the urethra and 1-second measurements were performed for 60s after each needle implant. Measurements were also performed at multiple positions along the urethra once all the needles were inserted. The procedure was then repeated with the PSD placed at the rectal wall. Results: Individual dose-rates ranging from 0.07µGy/s to 1.5µGy/s were measured after each needle implant. The average absolute relative differences were (6.2±3.6)% and (6.9±6.5)% to the values calculated with the TG-43 formalism, for the urethra and rectal wall respectively. These results are within expectations from the error uncertainty budget once accounting for uncertainties in seeds’ strength and positioning. Interestingly, the PSD allowed for unplanned error detection as the study was performed. Finally, the measured dose after the full implant at different positions along the mimicked organs at risk were in agreement with TG-43 values for all of the positions tested. Conclusion: Plastic scintillation detectors could be used as in vivo detectors for LDR brachytherapy as they would provide accurate dose information after each needle implant as well as along the organs at risk at the end of the implant.« less

  20. Developmental plasticity and language: A comparative perspective

    PubMed Central

    Griebel, Ulrike; Pepperberg, Irene; Oller, D. Kimbrough

    2016-01-01

    The growing field of evo-devo is increasingly demonstrating the complexity of steps involved in genetic, intracellular regulatory, and extracellular environmental control of the development of phenotypes. A key result of such work is an account for the remarkable plasticity of organismal form in many species based on relatively minor changes in regulation of highly conserved genes and genetic processes. Accounting for behavioral plasticity is of similar potential interest but has received far less attention. Of particular interest is plasticity in communication systems, where human language represents an ultimate target for research. The present paper considers plasticity of language capabilities in a comparative framework, focusing attention on examples of a remarkable fact: Whereas there exist design features of mature human language that have never been observed to occur in nonhumans in the wild, many of these features can be developed to notable extents when nonhumans are enculturated through human training (especially with intensive social interaction). These examples of enculturated developmental plasticity across extremely diverse taxa suggest, consistent with the evo-devo theme of highly conserved processes in evolution, that human language is founded in part on cognitive capabilities that are indeed ancient and that even modern humans show self-organized emergence of many language capabilities in the context of rich enculturation, built on the special social/ecological history of the hominin line. Human culture can thus be seen as a regulatory system encouraging language development in the context of a cognitive background with many highly conserved features. PMID:27003391

  1. Optical absorption in recycled waste plastic polyethylene

    NASA Astrophysics Data System (ADS)

    Aji, M. P.; Rahmawati, I.; Priyanto, A.; Karunawan, J.; Wati, A. L.; Aryani, N. P.; Susanto; Wibowo, E.; Sulhadi

    2018-03-01

    We investigated the optical properties of UV spectrum absorption in recycled waste plastic from polyethylene polymer type. Waste plastic polyethylene showed an optical spectrum absorption after it’s recycling process. Spectrum absorption is determined using spectrophotometer UV-Nir Ocean Optics type USB 4000. Recycling method has been processed using heating treatment around the melting point temperature of the polyethylene polymer that are 200°C, 220°C, 240°C, 260°C, and 280°C. In addition, the recycling process was carried out with time variations as well, which are 1h, 1.5h, 2h, and 2.5h. The result of this experiment shows that recycled waste plastic polyethylene has a spectrum absorption in the ∼ 340-550 nm wavelength range. The absorbance spectrum obtained from UV light which is absorbed in the orbital n → π* and the orbital π → π*. This process indicates the existence of electron transition phenomena. This mechanism is affected by the temperature and the heating time where the intensity of absorption increases and widens with the increase of temperature and heating time. Furthermore this study resulted that the higher temperature affected the enhancement of the band gap energy of waste plastic polyethylene. These results show that recycled waste plastic polyethylene has a huge potential to be absorber materials for solar cell.

  2. Plastic Surgery Response in Natural Disasters.

    PubMed

    Chung, Susan; Zimmerman, Amanda; Gaviria, Andres; Dayicioglu, Deniz

    2015-06-01

    Disasters cause untold damage and are often unpredictable; however, with proper preparation, these events can be better managed. The initial response has the greatest impact on the overall success of the relief effort. A well-trained multidisciplinary network of providers is necessary to ensure coordinated care for the victims of these mass casualty disasters. As members of this network of providers, plastic surgeons have the ability to efficiently address injuries sustained in mass casualty disasters and are a valuable member of the relief effort. The skill set of plastic surgeons includes techniques that can address injuries sustained in large-scale emergencies, such as the management of soft-tissue injury, tissue viability, facial fractures, and extremity salvage. An approach to disaster relief, the types of disasters encountered, the management of injuries related to mass casualty disasters, the role of plastic surgeons in the relief effort, and resource management are discussed. In order to improve preparedness in future mass casualty disasters, plastic surgeons should receive training during residency regarding the utilization of plastic surgery knowledge in the disaster setting.

  3. Emergent spatial synaptic structure from diffusive plasticity.

    PubMed

    Sweeney, Yann; Clopath, Claudia

    2017-04-01

    Some neurotransmitters can diffuse freely across cell membranes, influencing neighbouring neurons regardless of their synaptic coupling. This provides a means of neural communication, alternative to synaptic transmission, which can influence the way in which neural networks process information. Here, we ask whether diffusive neurotransmission can also influence the structure of synaptic connectivity in a network undergoing plasticity. We propose a form of Hebbian synaptic plasticity which is mediated by a diffusive neurotransmitter. Whenever a synapse is modified at an individual neuron through our proposed mechanism, similar but smaller modifications occur in synapses connecting to neighbouring neurons. The effects of this diffusive plasticity are explored in networks of rate-based neurons. This leads to the emergence of spatial structure in the synaptic connectivity of the network. We show that this spatial structure can coexist with other forms of structure in the synaptic connectivity, such as with groups of strongly interconnected neurons that form in response to correlated external drive. Finally, we explore diffusive plasticity in a simple feedforward network model of receptive field development. We show that, as widely observed across sensory cortex, the preferred stimulus identity of neurons in our network become spatially correlated due to diffusion. Our proposed mechanism of diffusive plasticity provides an efficient mechanism for generating these spatial correlations in stimulus preference which can flexibly interact with other forms of synaptic organisation. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Experience-driven plasticity in binocular vision

    PubMed Central

    Klink, P. Christiaan; Brascamp, Jan W.; Blake, Randolph; van Wezel, Richard J.A.

    2010-01-01

    Summary Experience-driven neuronal plasticity allows the brain to adapt its functional connectivity to recent sensory input. Here we use binocular rivalry [1], an experimental paradigm where conflicting images are presented to the individual eyes, to demonstrate plasticity in the neuronal mechanisms that convert visual information from two separated retinas into single perceptual experiences. Perception during binocular rivalry tended to initially consist of alternations between exclusive representations of monocularly defined images, but upon prolonged exposure, mixture percepts became more prevalent. The completeness of suppression, reflected in the incidence of mixture percepts, plausibly reflects the strength of inhibition that likely plays a role in binocular rivalry [2]. Recovery of exclusivity was possible, but required highly specific binocular stimulation. Documenting the prerequisites for these observed changes in perceptual exclusivity, our experiments suggest experience-driven plasticity at interocular inhibitory synapses, driven by the (lack of) correlated activity of neurons representing the conflicting stimuli. This form of plasticity is consistent with a previously proposed, but largely untested, anti-Hebbian learning mechanism for inhibitory synapses in vision [3, 4]. Our results implicate experience-driven plasticity as one governing principle in the neuronal organization of binocular vision. PMID:20674360

  5. Phyllosphere yeasts rapidly break down biodegradable plastics

    PubMed Central

    2011-01-01

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands. PMID:22126328

  6. Neuron-glia metabolic coupling and plasticity.

    PubMed

    Magistretti, Pierre J

    2006-06-01

    The coupling between synaptic activity and glucose utilization (neurometabolic coupling) is a central physiological principle of brain function that has provided the basis for 2-deoxyglucose-based functional imaging with positron emission tomography (PET). Astrocytes play a central role in neurometabolic coupling, and the basic mechanism involves glutamate-stimulated aerobic glycolysis; the sodium-coupled reuptake of glutamate by astrocytes and the ensuing activation of the Na-K-ATPase triggers glucose uptake and processing via glycolysis, resulting in the release of lactate from astrocytes. Lactate can then contribute to the activity-dependent fuelling of the neuronal energy demands associated with synaptic transmission. An operational model, the 'astrocyte-neuron lactate shuttle', is supported experimentally by a large body of evidence, which provides a molecular and cellular basis for interpreting data obtained from functional brain imaging studies. In addition, this neuron-glia metabolic coupling undergoes plastic adaptations in parallel with adaptive mechanisms that characterize synaptic plasticity. Thus, distinct subregions of the hippocampus are metabolically active at different time points during spatial learning tasks, suggesting that a type of metabolic plasticity, involving by definition neuron-glia coupling, occurs during learning. In addition, marked variations in the expression of genes involved in glial glycogen metabolism are observed during the sleep-wake cycle, with in particular a marked induction of expression of the gene encoding for protein targeting to glycogen (PTG) following sleep deprivation. These data suggest that glial metabolic plasticity is likely to be concomitant with synaptic plasticity.

  7. Radiation crosslinking of highly plasticized PVC

    NASA Astrophysics Data System (ADS)

    Mendizabal, E.; Cruz, L.; Jasso, C. F.; Burillo, G.; Dakin, V. I.

    1996-02-01

    To improve the physical properties of highly plasticized PVC, the polymer was crosslinked by gamma irradiation using a dose rate of 91 kGy/h. The effect of plasticizer type was studied by using three different plasticizers, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), di(2-ethyl hexyl) phthalate (DOP), and di(2-ethylhexyl terephthalate) (DOTP), and varying irradiation doses. Gel content was determined by soxhlet extraction, tensile measurements were made on a universal testing machine and the mechano-dynamic measurements were made in a dynamic rheometer. It was found that a considerable bonding of plasticizer molecules to macromolelcules takes place along with crosslinking, so that the use of the solvent extraction method for measuring the degree of crosslinking can give erroneous information. Radiation-chemical crosslinking yield ( Gc) and molecular weight of interjunctions chains ( Mc), were calculated for different systems studied. Addition of ethylene glycol dimethacrylate (EGDM) as a crosslinking coagent and dioctyl tin oxide (DOTO) as a stabilizer was also studied. Plasticizers extraction resistance was increased by irradiation treatment.

  8. Role of Plastics on Human Health.

    PubMed

    Kumar, Pramod

    2018-05-01

    Plastics, currently the universal workhorse materials of modern economy, because of their low cost and varied functional properties are posing serious threat to environment and consumer's health in many direct and indirect ways. Rising concern about the impact of plastics on environment and human health, has forced the industry to look for alternatives. This review studies current understanding of benefits and concerns surrounding use of plastics, reviews literature about health effects in humans and discusses the current state of evidence, as well as future research trends. There is increasing concern regarding additives in plastics to which most people are exposed, such as phthalates, bisphenol A or polybrominated diphenyl ethers (PBDE), and their detection in humans, leading to harmful impact on health. The studies are divided, among many other issues on the fact of considering these additives as carcinogens or toxicants, but there is a consensus that these chemicals have the ability to alter the endocrine system. Human data are limited compared to large body of experimental evidence documenting reproductive or developmental toxicity in relation to these compounds in animals. The concentrations of these additives in young children, a segment particularly sensitive to exogenous insults, are typically higher, indicating the need to decrease exposure to these compounds. The rapid increase in usage of plastics and increased awareness about its health hazard has lent urgency to the whole issue.

  9. Epigenetic Basis of Neuronal and Synaptic Plasticity.

    PubMed

    Karpova, Nina N; Sales, Amanda J; Joca, Samia R

    2017-01-01

    Neuronal network and plasticity change as a function of experience. Altered neural connectivity leads to distinct transcriptional programs of neuronal plasticity-related genes. The environmental challenges throughout life may promote long-lasting reprogramming of gene expression and the development of brain disorders. The modifications in neuronal epigenome mediate gene-environmental interactions and are required for activity-dependent regulation of neuronal differentiation, maturation and plasticity. Here, we highlight the latest advances in understanding the role of the main players of epigenetic machinery (DNA methylation and demethylation, histone modifications, chromatin-remodeling enzymes, transposons, and non-coding RNAs) in activity-dependent and long- term neural and synaptic plasticity. The review focuses on both the transcriptional and post-transcriptional regulation of gene expression levels, including the processes of promoter activation, alternative splicing, regulation of stability of gene transcripts by natural antisense RNAs, and alternative polyadenylation. Further, we discuss the epigenetic aspects of impaired neuronal plasticity and the pathogenesis of neurodevelopmental (Rett syndrome, Fragile X Syndrome, genomic imprinting disorders, schizophrenia, and others), stressrelated (mood disorders) and neurodegenerative Alzheimer's, Parkinson's and Huntington's disorders. The review also highlights the pharmacological compounds that modulate epigenetic programming of gene expression, the potential treatment strategies of discussed brain disorders, and the questions that should be addressed during the development of effective and safe approaches for the treatment of brain disorders.

  10. Core Characteristics Deterioration due to Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Kaido, Chikara; Arai, Satoshi

    This paper discusses the effect of plastic deformation at core manufacturing on the characteristics of cores where non-oriented electrical steel sheets are used as core material. Exciting field and iron loss increase proportionally to plastic deformation in the case of rP<10, where rP is a ratio of plastic deformation to that at yield point. In this region, anomalous eddy currents increase because plastic deformations of crystalline grains are distributed and then the flux distribution is induced. In the case of rP>20, the deterioration tend to saturate, and the increases in magnetic field and iron loss are 1000 to 1500A/m and 2 to 4W/kg. They are related to grain size, and high grade with larger grain may have lager field increase and smaller iron loss increase. Anomalous eddy current losses scarcely increase in this region. In actual motors, the plastic deformation affects iron loss increase although exciting current increases a little.

  11. Neural plasticity of development and learning.

    PubMed

    Galván, Adriana

    2010-06-01

    Development and learning are powerful agents of change across the lifespan that induce robust structural and functional plasticity in neural systems. An unresolved question in developmental cognitive neuroscience is whether development and learning share the same neural mechanisms associated with experience-related neural plasticity. In this article, I outline the conceptual and practical challenges of this question, review insights gleaned from adult studies, and describe recent strides toward examining this topic across development using neuroimaging methods. I suggest that development and learning are not two completely separate constructs and instead, that they exist on a continuum. While progressive and regressive changes are central to both, the behavioral consequences associated with these changes are closely tied to the existing neural architecture of maturity of the system. Eventually, a deeper, more mechanistic understanding of neural plasticity will shed light on behavioral changes across development and, more broadly, about the underlying neural basis of cognition. (c) 2010 Wiley-Liss, Inc.

  12. Stress and plasticity in Cu thin films

    NASA Astrophysics Data System (ADS)

    Weihnacht, Volker; Brückner, Winfried

    1999-11-01

    Aim of the work was to get more detailed knowledge about the processes of plasticity in thin Cu films. For this purpose, stress measurements and microstructural investigations have been done on 535nm thick Cu films on oxidized Si substrates. The film stress was measured by wafer-curvature technique using a home-made laser-optical apparatus. This apparatus allowed four-point bending experiments additionally to thermal cycling. It turned out that applied bending strains even higher than 0.5% did not leave significant plastic strains after relief of bending stress. It is concluded, that the elastic interaction of parallel dislocations at the film-substrate interface may play an important role in strain hardening even after small plastic strains.

  13. Botulinum Toxin Use in Pediatric Plastic Surgery.

    PubMed

    Fu, Katherine J; Teichgraeber, John F; Greives, Matthew R

    2016-11-01

    Botulinum toxin has increasingly become a prevalent treatment option for a wide range of conditions, many of which have their roots in plastic surgery and have been well studied. In adults, chronic headache, hyperhidrosis, and facial muscular hypertrophy have been effectively treated with botulinum toxin, and emerging studies have begun looking at its efficacy in children, as well. Successful treatment of spasticity and muscular contraction has allowed for the creation of safety profiles and dosage guidelines for botulinum toxin usage in children. The expanded indications for its use have since flourished in all arenas of pediatric care, including plastic surgery. Recent studies have described the use of botulinum toxin as an adjunct to the treatment of congenital torticollis and cleft lip. This review discusses the various applications of botulinum toxin for pediatric patients in the field of plastic surgery.

  14. The unaccountability case of plastic pellet pollution.

    PubMed

    Karlsson, Therese M; Arneborg, Lars; Broström, Göran; Almroth, Bethanie Carney; Gipperth, Lena; Hassellöv, Martin

    2018-04-01

    Plastic preproduction pellets are found in environmental samples all over the world and their presence is often linked to spills during production and transportation. To better understand how these pellets end up in the environment we assessed the release of plastic pellets from a polyethylene production site in a case study area on the Swedish west coast. The case study encompasses; field measurements to evaluate the level of pollution and pathways, models and drifters to investigate the potential spread and a revision of the legal framework and the company permits. This case study show that millions of pellets are released from the production site annually but also that there are national and international legal frameworks that if implemented could help prevent these spills. Bearing in mind the negative effects observed by plastic pollution there is an urgent need to increase the responsibility and accountability of these spills. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  15. Influence of Inflammation on Poststroke Plasticity

    PubMed Central

    Kossut, Malgorzata

    2013-01-01

    Age-related brain injuries including stroke are a leading cause of morbidity and mental disability worldwide. Most patients who survive stroke experience some degree of recovery. The restoration of lost functions can be explained by neuronal plasticity, understood as brain ability to reorganize and remodel itself in response to changed environmental requirements. However, stroke triggers a cascade of events which may prevent the normal development of the plastic changes. One of them may be inflammatory response initiated immediately after stroke, which has been found to contribute to neuronal injury. Some recent evidence though has suggested that inflammatory reaction can be also neuroprotective. This paper attempts to discuss the influence of poststroke inflammatory response on brain plasticity and stroke outcome. We also describe the recent anti-inflammatory strategies that have been effective for recovery in experimental stroke. PMID:23533818

  16. Optical Sensors Based on Plastic Fibers

    PubMed Central

    Bilro, Lúcia; Alberto, Nélia; Pinto, João L.; Nogueira, Rogério

    2012-01-01

    The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented. PMID:23112707

  17. Onset of Plasticity via Relaxation Analysis (OPRA)

    SciTech Connect

    Pandey, Amit; Wheeler, Robert; Shyam, Amit

    In crystalline metals and alloys, plasticity occurs due to the movement of mobile dislocations and the yield stress for engineering applications is traditionally quantified based on strain. The onset of irreversible plasticity or “yielding” is generally identified by a deviation from linearity in the stress-strain plot or by some standard convention such as 0.2 % offset strain relative to the “linear elastic response”. In the present work, we introduce a new methodology for the determination of the true yield point based on stress relaxation. We show experimentally that this determination is self-consistent in nature and, as such, provides an objectivemore » observation of the very onset of plastic flow. Lastly, our designation for yielding is no longer related to the shape of the stress-strain curve but instead reflects the earliest signature of the activation of concerted irreversible dislocation motion in a test specimen under increasing load.« less

  18. Onset of Plasticity via Relaxation Analysis (OPRA)

    DOE PAGES

    Pandey, Amit; Wheeler, Robert; Shyam, Amit; ...

    2016-03-17

    In crystalline metals and alloys, plasticity occurs due to the movement of mobile dislocations and the yield stress for engineering applications is traditionally quantified based on strain. The onset of irreversible plasticity or “yielding” is generally identified by a deviation from linearity in the stress-strain plot or by some standard convention such as 0.2 % offset strain relative to the “linear elastic response”. In the present work, we introduce a new methodology for the determination of the true yield point based on stress relaxation. We show experimentally that this determination is self-consistent in nature and, as such, provides an objectivemore » observation of the very onset of plastic flow. Lastly, our designation for yielding is no longer related to the shape of the stress-strain curve but instead reflects the earliest signature of the activation of concerted irreversible dislocation motion in a test specimen under increasing load.« less

  19. Epigenetics and developmental plasticity across species.

    PubMed

    Champagne, Frances A

    2013-01-01

    Plasticity is a typical feature of development and can lead to divergent phenotypes. There is increasing evidence that epigenetic mechanisms, such as DNA methylation, are present across species, are modifiable by the environment, and are involved in developmental plasticity. Thus, in the context of the concept of developmental homology, epigenetic mechanisms may serve to create a process homology between species by providing a common molecular pathway through which environmental experiences shape development, ultimately leading to phenotypic diversity. This article will highlight evidence derived from across-species investigations of epigenetics, development, and plasticity which may contribute to our understanding of the homology that exists between species and between ancestors and descendants. Copyright © 2012 Wiley Periodicals, Inc.

  20. Enhancing contrast of fingerprints on plastic tape.

    PubMed

    Steele, Charles A; Ball, Mikki S

    2003-11-01

    Many of the currently available fingerprinting methods have limited ability to visualize fingerprints on plastic tape without expensive equipment or significant handling of the sample. This is especially true for visualizing fingerprints on black electrical tape. This study sought a hands-off method to produce easy visualization of fingerprints on different types of plastic tape, including black electrical tape, without the need for expensive equipment. The methods selected were to sublime disperse dyes into the tape, both with and without the fuming of cyanoacrylate, everywhere except for where the fingerprint was applied. The resulting color contrasts provided enough differentiation to visualize fingerprints on plastic tape under ambient light. Sequential fuming with cyanoacrylate followed by disperse dyes provided the best visualizations on all tapes, and cyanoacrylate followed by disperse yellow 211 clearly visualized fingerprints on black electrical tape.

  1. Plastic deformation in a metallic granular chain

    NASA Astrophysics Data System (ADS)

    Musson, Ryan W.; Carlson, William

    2016-03-01

    Solitary wave response was investigated in a metallic granular chain-piston system using LS-DYNA. A power law hardening material model was used to show that localized plastic deformation is present in a metallic granular chain for an impact velocity of 0.5 m/s. This loss due to plastic deformation was quantified via impulse, and it was shown that the loss scales nearly linearly with impact velocity. Therefore, metallic grains may not be suitable for devices that require high-amplitude solitary waves. There would be too much energy lost to plastic deformation. One can assume that ceramics will behave elastically; therefore, the response of an aluminum oxide granular chain was compared to that of a steel chain.

  2. The Corticohippocampal Circuit, Synaptic Plasticity, and Memory

    PubMed Central

    Basu, Jayeeta; Siegelbaum, Steven A.

    2015-01-01

    Synaptic plasticity serves as a cellular substrate for information storage in the central nervous system. The entorhinal cortex (EC) and hippocampus are interconnected brain areas supporting basic cognitive functions important for the formation and retrieval of declarative memories. Here, we discuss how information flow in the EC–hippocampal loop is organized through circuit design. We highlight recently identified corticohippocampal and intrahippocampal connections and how these long-range and local microcircuits contribute to learning. This review also describes various forms of activity-dependent mechanisms that change the strength of corticohippocampal synaptic transmission. A key point to emerge from these studies is that patterned activity and interaction of coincident inputs gives rise to associational plasticity and long-term regulation of information flow. Finally, we offer insights about how learning-related synaptic plasticity within the corticohippocampal circuit during sensory experiences may enable adaptive behaviors for encoding spatial, episodic, social, and contextual memories. PMID:26525152

  3. Miniature plastic gripper and fabrication method

    DOEpatents

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

    1997-03-11

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same are disclosed. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or closed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis. 8 figs.

  4. Fabrication method for miniature plastic gripper

    DOEpatents

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

    1998-07-21

    A miniature plastic gripper is described actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or dosed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis. 8 figs.

  5. Fabrication method for miniature plastic gripper

    DOEpatents

    Benett, William J.; Krulevitch, Peter A.; Lee, Abraham P.; Northrup, Milton A.; Folta, James A.

    1998-01-01

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or dosed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis.

  6. Miniature plastic gripper and fabrication method

    DOEpatents

    Benett, William J.; Krulevitch, Peter A.; Lee, Abraham P.; Northrup, Milton A.; Folta, James A.

    1997-01-01

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or closed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis.

  7. Benthic plastic debris in marine and fresh water environments.

    PubMed

    Corcoran, Patricia L

    2015-08-01

    This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

  8. Early microbial biofilm formation on marine plastic debris.

    PubMed

    Lobelle, Delphine; Cunliffe, Michael

    2011-01-01

    An important aspect of the global problem of plastic debris pollution is plastic buoyancy. There is some evidence that buoyancy is influenced by attached biofilms but as yet this is poorly understood. We submerged polyethylene plastic in seawater and sampled weekly for 3 weeks in order to study early stage processes. Microbial biofilms developed rapidly on the plastic and coincided with significant changes in the physicochemical properties of the plastic. Submerged plastic became less hydrophobic and more neutrally buoyant during the experiment. Bacteria readily colonised the plastic but there was no indication that plastic-degrading microorganisms were present. This study contributes to improved understanding of the fate of plastic debris in the marine environment. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Polychlorinated biphenyls and organochlorine pesticides in plastics ingested by seabirds.

    PubMed

    Colabuono, Fernanda Imperatrice; Taniguchi, Satie; Montone, Rosalinda Carmela

    2010-04-01

    The occurrence of plastic objects in the digestive tract was assessed in eight species of Procellariiformes collected in southern Brazil and the occurrence of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the ingested plastics pellets and plastic fragments was evaluated. PCBs were detected in plastic pellets (491 ng g(-1)) and plastic fragments (243-418 ng g(-1)). Among the OCPs, p,p'-DDE had the highest concentrations, ranging from 68.0 to 99.0 ng g(-1). The occurrence of organic pollutants in post-consumer plastics supports the fact that plastics are an important source carrying persistent organic pollutants in the marine environment. Although transfer through the food chain may be the main source of exposure to POPs to seabirds, plastics could be an additional source for the organisms which ingest them, like Procellariiformes which are the seabirds most affected by plastic pollution. (c) 2010 Elsevier Ltd. All rights reserved.

  10. Towards the effective plastic waste management in Bangladesh: a review.

    PubMed

    Mourshed, Monjur; Masud, Mahadi Hasan; Rashid, Fazlur; Joardder, Mohammad Uzzal Hossain

    2017-12-01

    The plastic-derived product, nowadays, becomes an indispensable commodity for different purposes. A huge amount of used plastic causes environmental hazards that turn in danger for marine life, reduces the fertility of soil, and contamination of ground water. Management of this enormous plastic waste is challenging in particular for developing countries like Bangladesh. Lack of facilities, infrastructure development, and insufficient budget for waste management are some of the prime causes of improper plastic management in Bangladesh. In this study, the route of plastic waste production and current plastic waste management system in Bangladesh have been reviewed extensively. It emerges that no technical and improved methods are adapted in the plastic management system. A set of the sustainable plastic management system has been proposed along with the challenges that would emerge during the implementation these strategies. Successful execution of the proposed systems would enhance the quality of plastic waste management in Bangladesh and offers enormous energy from waste.

  11. Use of recycled plastics in concrete: A critical review.

    PubMed

    Gu, Lei; Ozbakkaloglu, Togay

    2016-05-01

    Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Thermodynamic theory of dislocation-enabled plasticity

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2017-11-01

    The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects, yielding transitions, and adiabatic shear banding.

  13. Antifriction basalt-plastics based on polypropylene

    NASA Astrophysics Data System (ADS)

    Bashtannik, P. I.; Ovcharenko, V. G.

    1997-05-01

    A study is made of the dependence of the mechanical and friction-engineering properties of polypropylene reinforced with basalt fibers on the viscosity of the polymer matrix. It is established that the main factors that determine the mechanical properties of the plastics are the quality of impregnation of the fibers by the binder and the residual length of the reinforcing filler in the composite after extrusion and injection molding. The material that was developed has a low friction coefficient and low rate of wear within a relatively brood range of friction conditions. The basalt-plastics can be used in the rubbing parts of machines and mechanisms subjected to dry friction.

  14. Epigenetic Influences on Brain Development and Plasticity

    PubMed Central

    Fagiolini, Michela; Jensen, Catherine L.; Champagne, Frances A.

    2009-01-01

    A fine interplay exists between sensory experience and innate genetic programs leading to the sculpting of neuronal circuits during early brain development. Recent evidence suggests that the dynamic regulation of gene expression through epigenetic mechanisms is at the interface between environmental stimuli and long-lasting molecular, cellular and complex behavioral phenotypes acquired during periods of developmental plasticity. Understanding these mechanisms may give insight into the formation of critical periods and provide new strategies for increasing plasticity and adaptive change in adulthood. PMID:19545993

  15. Intravital imaging of dendritic spine plasticity

    PubMed Central

    Sau Wan Lai, Cora

    2014-01-01

    Abstract Dendritic spines are the postsynaptic part of most excitatory synapses in the mammalian brain. Recent works have suggested that the structural and functional plasticity of dendritic spines have been associated with information coding and memories. Advances in imaging and labeling techniques enable the study of dendritic spine dynamics in vivo. This perspective focuses on intravital imaging studies of dendritic spine plasticity in the neocortex. I will introduce imaging tools for studying spine dynamics and will further review current findings on spine structure and function under various physiological and pathological conditions. PMID:28243511

  16. Bidirectional optical coupler for plastic optical fibers.

    PubMed

    Sugita, Tatsuya; Abe, Tomiya; Hirano, Kouki; Itoh, Yuzo

    2005-05-20

    We have developed a low-loss bidirectional optical coupler for high-speed optical communication with plastic optical fibers (POFs). The coupler, which is fabricated by an injection molding method that uses poly (methyl methacrylate), has an antisymmetric tapered shape. We show that the coupler has low insertion and branching losses. The tapered shape of the receiving branch reduces beam diameter and increases detection efficiency coupling to a photodetector, whose area is smaller than that of the plastic optical fiber. The possibility of more than 15-m bidirectional transmission with a signaling bit rate up to 500 Mbits/s for simplex step-index POFs is demonstrated.

  17. Plastics in soil: Analytical methods and possible sources.

    PubMed

    Bläsing, Melanie; Amelung, Wulf

    2018-01-15

    At least 300 Mio t of plastic are produced annually, from which large parts end up in the environment, where it persists over decades, harms biota and enters the food chain. Yet, almost nothing is known about plastic pollution of soil; hence, the aims of this work are to review current knowledge on i) available methods for the quantification and identification of plastic in soil, ii) the quantity and possible input pathways of plastic into soil, (including first preliminary screening of plastic in compost), and iii) its fate in soil. Methods for plastic analyses in sediments can potentially be adjusted for application to soil; yet, the applicability of these methods for soil needs to be tested. Consequently, the current data base on soil pollution with plastic is still poor. Soils may receive plastic inputs via plastic mulching or the application of plastic containing soil amendments. In compost up to 2.38-1200mg plastic kg -1 have been found so far; the plastic concentration of sewage sludge varies between 1000 and 24,000 plastic items kg -1 . Also irrigation with untreated and treated wastewater (1000-627,000 and 0-125,000 plastic items m -3 , respectively) as well as flooding with lake water (0.82-4.42 plastic items m -3 ) or river water (0-13,751 items km -2 ) can provide major input pathways for plastic into soil. Additional sources comprise littering along roads and trails, illegal waste dumping, road runoff as well as atmospheric input. With these input pathways, plastic concentrations in soil might reach the per mill range of soil organic carbon. Most of plastic (especially >1μm) will presumably be retained in soil, where it persists for decades or longer. Accordingly, further research on the prevalence and fate of such synthetic polymers in soils is urgently warranted. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Flotation separation of waste plastics for recycling-A review.

    PubMed

    Wang, Chong-qing; Wang, Hui; Fu, Jian-gang; Liu, You-nian

    2015-07-01

    The sharp increase of plastic wastes results in great social and environmental pressures, and recycling, as an effective way currently available to reduce the negative impacts of plastic wastes, represents one of the most dynamic areas in the plastics industry today. Froth flotation is a promising method to solve the key problem of recycling process, namely separation of plastic mixtures. This review surveys recent literature on plastics flotation, focusing on specific features compared to ores flotation, strategies, methods and principles, flotation equipments, and current challenges. In terms of separation methods, plastics flotation is divided into gamma flotation, adsorption of reagents, surface modification and physical regulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Accumulation of plastic-derived chemicals in tissues of seabirds ingesting marine plastics.

    PubMed

    Tanaka, Kosuke; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Fukuwaka, Masa-aki; Watanuki, Yutaka

    2013-04-15

    We analyzed polybrominated diphenyl ethers (PBDEs) in abdominal adipose of oceanic seabirds (short-tailed shearwaters, Puffinus tenuirostris) collected in northern North Pacific Ocean. In 3 of 12 birds, we detected higher-brominated congeners (viz., BDE209 and BDE183), which are not present in the natural prey (pelagic fish) of the birds. The same compounds were present in plastic found in the stomachs of the 3 birds. These data suggested the transfer of plastic-derived chemicals from ingested plastics to the tissues of marine-based organisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. A Self-Instructional System in Plastics.

    ERIC Educational Resources Information Center

    Greene, Mark M.; And Others

    The purpose of this system is to teach rural high school students the process of forming objects with expandable polystyrene plastic beads. Instruction in the system generally follows a three-step sequence in which the student: 1) views one of the four demonstration films; 2) progresses through a corresponding programed instruction book; and 3)…

  1. Diffusion of herbicides through plastic film

    USGS Publications Warehouse

    Bridges, W.R.; Sanders, Herman O.

    1963-01-01

    Plastic film have been used by fishery workers as barriers to subdivide experimental ponds in order to assess the value of some chemical treatment, and as test vessels to contain dilute solutions or suspensions of toxic chemicals in experiments conducted to establish tolerance levels of these chemicals for fish.

  2. Telemedicine and Plastic Surgery: A Pilot Study.

    PubMed

    Valente, Denis Souto; Silveira Eifler, Luciano; Carvalho, Lauro Aita; Filho, Gustavo Azambuja Pereira; Ribeiro, Vinicius Weissheimer; Padoin, Alexandre Vontobel

    2015-01-01

    Background. Telemedicine can be defined as the use of electronic media for transmission of information and medical data from one site to another. The objective of this study is to demonstrate an experience of telemedicine in plastic surgery. Methods. 32 plastic surgeons received a link with password for real-time streaming of a surgery. At the end of the procedure, the surgeons attending the procedure by the Internet answered five questions. The results were analyzed with descriptive statistics. Results. 27 plastic surgeons attended the online procedure in real-time. 96.3% considered the access to the website as good or excellent and 3.7% considered it bad. 14.8% reported that the transmission was bad and 85.2% considered the quality of transmission as good or excellent. 96.3% classified the live broadcasting as a good or excellent learning experience and 3.7% considered it a bad experience. 92.6% reported feeling able to perform this surgery after watching the demo and 7.4% did not feel able. 100% of participants said they would like to participate in other surgical demonstrations over the Internet. Conclusion. We conclude that the use of telemedicine can provide more access to education and medical research, for plastic surgeons looking for medical education from distant regions.

  3. Plasticity of Altruistic Behavior in Children

    ERIC Educational Resources Information Center

    Lozada, Mariana; D'Adamo, Paola; Carro, Natalia

    2014-01-01

    The present study investigates the plasticity of altruistic behavior in children, analyzing the effect of a short intervention on 6- to 7-year-olds. After a 10-session intervention performed in a school context, altruism significantly increased. The intervention, which included relaxation practices, cooperative activities and emotional security…

  4. Optimization of wood plastic composite decks

    NASA Astrophysics Data System (ADS)

    Ravivarman, S.; Venkatesh, G. S.; Karmarkar, A.; Shivkumar N., D.; Abhilash R., M.

    2018-04-01

    Wood Plastic Composite (WPC) is a new class of natural fibre based composite material that contains plastic matrix reinforced with wood fibres or wood flour. In the present work, Wood Plastic Composite was prepared with 70-wt% of wood flour reinforced in polypropylene matrix. Mechanical characterization of the composite was done by carrying out laboratory tests such as tensile test and flexural test as per the American Society for Testing and Materials (ASTM) standards. Computer Aided Design (CAD) model of the laboratory test specimen (tensile test) was created and explicit finite element analysis was carried out on the finite element model in non-linear Explicit FE code LS - DYNA. The piecewise linear plasticity (MAT 24) material model was identified as a suitable model in LS-DYNA material library, describing the material behavior of the developed composite. The composite structures for decking application in construction industry were then optimized for cross sectional area and distance between two successive supports (span length) by carrying out various numerical experiments in LS-DYNA. The optimized WPC deck (Elliptical channel-2 E10) has 45% reduced weight than the baseline model (solid cross-section) considered in this study with the load carrying capacity meeting acceptance criterion (allowable deflection & stress) for outdoor decking application.

  5. Transmission, Development, and Plasticity of Synapses

    PubMed Central

    Harris, Kathryn P.

    2015-01-01

    Chemical synapses are sites of contact and information transfer between a neuron and its partner cell. Each synapse is a specialized junction, where the presynaptic cell assembles machinery for the release of neurotransmitter, and the postsynaptic cell assembles components to receive and integrate this signal. Synapses also exhibit plasticity, during which synaptic function and/or structure are modified in response to activity. With a robust panel of genetic, imaging, and electrophysiology approaches, and strong evolutionary conservation of molecular components, Drosophila has emerged as an essential model system for investigating the mechanisms underlying synaptic assembly, function, and plasticity. We will discuss techniques for studying synapses in Drosophila, with a focus on the larval neuromuscular junction (NMJ), a well-established model glutamatergic synapse. Vesicle fusion, which underlies synaptic release of neurotransmitters, has been well characterized at this synapse. In addition, studies of synaptic assembly and organization of active zones and postsynaptic densities have revealed pathways that coordinate those events across the synaptic cleft. We will also review modes of synaptic growth and plasticity at the fly NMJ, and discuss how pre- and postsynaptic cells communicate to regulate plasticity in response to activity. PMID:26447126

  6. Neuronal plasticity and seasonal reproduction in sheep

    PubMed Central

    Lehman, Michael N.; Ladha, Zamin; Coolen, Lique M.; Hileman, Stanley M.; Connors, John M.; Goodman, Robert L.

    2010-01-01

    Seasonal reproduction represents a naturally occurring example of functional plasticity in the adult brain since it reflects changes in neuroendocrine pathways controlling GnRH secretion and, in particular, the responsiveness of GnRH neurons to estradiol negative feedback. Structural plasticity within this neural circuitry may, in part, be responsible for seasonal switches in the negative feedback control of GnRH secretion that underlies annual reproductive transitions. In this paper, we review evidence for structural changes in the circuitry responsible for seasonal inhibition of GnRH secretion in sheep. These include changes in synaptic inputs onto GnRH neurons, as well as onto dopamine neurons in the A15 cell group, a nucleus that play a key role in estradiol negative feedback. We also present preliminary data suggesting a role for neurotrophins and neurotrophin receptors as an early mechanistic step in the plasticity that accompanies seasonal reproductive transitions in the sheep. Finally, we review recent evidence suggesting that kisspeptin cells of the arcuate nucleus constitute a critical intermediary in the control of seasonal reproduction. While a majority of the data for a role of neuronal plasticity in seasonal reproduction has come from the sheep model, the players and principles are likely to have relevance for reproduction in a wide variety of vertebrates, including humans, and in both health and disease. PMID:21143669

  7. Bacterial production of the biodegradable plastics polyhydroxyalkanoates.

    PubMed

    Urtuvia, Viviana; Villegas, Pamela; González, Myriam; Seeger, Michael

    2014-09-01

    Petroleum-based plastics constitute a major environmental problem due to their low biodegradability and accumulation in various environments. Therefore, searching for novel biodegradable plastics is of increasing interest. Microbial polyesters known as polyhydroxyalkanoates (PHAs) are biodegradable plastics. Life cycle assessment indicates that PHB is more beneficial than petroleum-based plastics. In this report, bacterial production of PHAs and their industrial applications are reviewed and the synthesis of PHAs in Burkholderia xenovorans LB400 is described. PHAs are synthesized by a large number of microorganisms during unbalanced nutritional conditions. These polymers are accumulated as carbon and energy reserve in discrete granules in the bacterial cytoplasm. 3-hydroxybutyrate and 3-hydroxyvalerate are two main PHA units among 150 monomers that have been reported. B. xenovorans LB400 is a model bacterium for the degradation of polychlorobiphenyls and a wide range of aromatic compounds. A bioinformatic analysis of LB400 genome indicated the presence of pha genes encoding enzymes of pathways for PHA synthesis. This study showed that B. xenovorans LB400 synthesize PHAs under nutrient limitation. Staining with Sudan Black B indicated the production of PHAs by B. xenovorans LB400 colonies. The PHAs produced were characterized by GC-MS. Diverse substrates for the production of PHAs in strain LB400 were analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. The demise of plastic encapsulated microcircuit myths

    NASA Astrophysics Data System (ADS)

    Hakim, E. B.; Agarwal, R. K.; Pecht, M.

    1994-10-01

    Production of microelectronic devices encapsulated in solid, molded plastic packages has rapidly increased since the early 1980's. Today, millions of plastic-encapsulated devices are produced daily. On the other hand, only a few million hermetic (cavity) packages are produced per year. Reasons for the increased use of plastic-encapsulated packages include cost, availability, size, weight, quality, and reliability. Markets taking advantage of this technology range from computers and telecommunications to automotive uses. Yet, several industries, the military in particular, will not accept such devices. One reason for this reluctance to use the best available commercial parts is a perceived risk of poor reliability, derived from antiquated military specifications, standards, and handbooks; other common justifications cite differing environments; inadequate screens; inadequate test data, and required government audits of suppliers' processes. This paper describes failure mechanisms associated with plastic encapsulation and their elimination. It provides data indicating the relative reliability of cavity and solid-encapsulated packaging, and presents possible approaches to assuring quality and reliability in the procuring and applying this successful commercial technology.

  9. Child health developmental plasticity, and epigenetic programming

    USDA-ARS?s Scientific Manuscript database

    Plasticity in developmental programming has evolved in order to provide the best chances of survival and reproductive success to the organism under changing environments. Environmental conditions that are experienced in early life can profoundly influence human biology and long-term health. Developm...

  10. Plastic Brains and the Dialectics of Dialectics

    ERIC Educational Resources Information Center

    Loxley, Andrew; Murphy, Colette; Seery, Aidan

    2014-01-01

    This article advances the thinking of Lima, Ostermann and Rezende's "Marxism in Vygotskian approaches to cultural studies of science education" and Mark Zuss' response to their paper. Firstly, it introduces Catherine Malabou's concept of plasticity, from which Hegel's dialectic can be re-read as historical materialist…

  11. Air void analyzer for plastic concrete.

    DOT National Transportation Integrated Search

    2008-10-01

    The two main test methods that measure the air content in plastic concrete are the pressure method and the volumetric : or roll-a-meter method. Although these methods report the total air in the concrete, they do not distinguish between : entrained a...

  12. Data-driven in computational plasticity

    NASA Astrophysics Data System (ADS)

    Ibáñez, R.; Abisset-Chavanne, E.; Cueto, E.; Chinesta, F.

    2018-05-01

    Computational mechanics is taking an enormous importance in industry nowadays. On one hand, numerical simulations can be seen as a tool that allows the industry to perform fewer experiments, reducing costs. On the other hand, the physical processes that are intended to be simulated are becoming more complex, requiring new constitutive relationships to capture such behaviors. Therefore, when a new material is intended to be classified, an open question still remains: which constitutive equation should be calibrated. In the present work, the use of model order reduction techniques are exploited to identify the plastic behavior of a material, opening an alternative route with respect to traditional calibration methods. Indeed, the main objective is to provide a plastic yield function such that the mismatch between experiments and simulations is minimized. Therefore, once the experimental results just like the parameterization of the plastic yield function are provided, finding the optimal plastic yield function can be seen either as a traditional optimization or interpolation problem. It is important to highlight that the dimensionality of the problem is equal to the number of dimensions related to the parameterization of the yield function. Thus, the use of sparse interpolation techniques seems almost compulsory.

  13. Development, maternal effects, and behavioral plasticity.

    PubMed

    Mateo, Jill M

    2014-11-01

    Behavioral, hormonal, and genetic processes interact reciprocally, and differentially affect behavior depending on ecological and social contexts. When individual differences are favored either between or within environments, developmental plasticity would be expected. Parental effects provide a rich source for phenotypic plasticity, including anatomical, physiological, and behavioral traits, because parents respond to dynamic cues in their environment and can, in turn, influence offspring accordingly. Because these inter-generational changes are plastic, parents can respond rapidly to changing environments and produce offspring whose phenotypes are well suited for current conditions more quickly than occurs with changes based on evolution through natural selection. I review studies on developmental plasticity and resulting phenotypes in Belding's ground squirrels (Urocitellus beldingi), an ideal species, given the competing demands to avoid predation while gaining sufficient weight to survive an upcoming hibernation, and the need for young to learn their survival behaviors. I will show how local environments and perceived risk of predation influence not only foraging, vigilance, and anti-predator behaviors, but also adrenal functioning, which may be especially important for obligate hibernators that face competing demands on the storage and mobilization of glucose. Mammalian behavioral development is sensitive to the social and physical environments provided by mothers during gestation and lactation. Therefore, maternal effects on offspring's phenotypes, both positive and negative, can be particularly strong. © The Author 2014. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

  14. Ocean acidification challenges copepod reproductive plasticity

    NASA Astrophysics Data System (ADS)

    Vehmaa, A.; Almén, A.-K.; Brutemark, A.; Paul, A.; Riebesell, U.; Furuhagen, S.; Engström-Öst, J.

    2015-11-01

    Ocean acidification is challenging phenotypic plasticity of individuals and populations. Calanoid copepods (zooplankton) are shown to be fairly plastic against altered pH conditions, and laboratory studies indicate that transgenerational effects are one mechanism behind this plasticity. We studied phenotypic plasticity of the copepod Acartia bifilosa in the course of a pelagic, large-volume mesocosm study that was conducted to investigate ecosystem and biogeochemical responses to ocean acidification. We measured copepod egg production rate, egg hatching success, adult female size and adult female antioxidant capacity (ORAC) as a function of acidification (fCO2 ~ 365-1231 μatm), and as a function of quantity and quality of their diet. We used an egg transplant experiment to reveal if transgenerational effects can alleviate the possible negative effects of ocean acidification on offspring development. We found significant negative effects of ocean acidification on adult female copepod size and egg hatching success. In addition, we found a threshold of fCO2 concentration (~ 1000 μatm), above which adaptive maternal effects cannot alleviate the negative effects of acidification on egg hatching and nauplii development. We did not find support for the hypothesis that insufficient food quantity (total particulate carbon ~ 55 μm) or quality (C : N) weakens the transgenerational effects. However, females with high ORAC produced eggs with high hatching success. Overall, these results indicate that A. bifilosa could be affected by projected near future CO2 levels.

  15. Ocean acidification challenges copepod phenotypic plasticity

    NASA Astrophysics Data System (ADS)

    Vehmaa, Anu; Almén, Anna-Karin; Brutemark, Andreas; Paul, Allanah; Riebesell, Ulf; Furuhagen, Sara; Engström-Öst, Jonna

    2016-11-01

    Ocean acidification is challenging phenotypic plasticity of individuals and populations. Calanoid copepods (zooplankton) are shown to be fairly plastic against altered pH conditions, and laboratory studies indicate that transgenerational effects are one mechanism behind this plasticity. We studied phenotypic plasticity of the copepod Acartia sp. in the course of a pelagic, large-volume mesocosm study that was conducted to investigate ecosystem and biogeochemical responses to ocean acidification. We measured copepod egg production rate, egg-hatching success, adult female size and adult female antioxidant capacity (ORAC) as a function of acidification (fCO2 ˜ 365-1231 µatm) and as a function of quantity and quality of their diet. We used an egg transplant experiment to reveal whether transgenerational effects can alleviate the possible negative effects of ocean acidification on offspring development. We found significant negative effects of ocean acidification on adult female size. In addition, we found signs of a possible threshold at high fCO2, above which adaptive maternal effects cannot alleviate the negative effects of acidification on egg-hatching and nauplii development. We did not find support for the hypothesis that insufficient food quantity (total particulate carbon < 55 µm) or quality (C : N) weakens the transgenerational effects. However, females with high-ORAC-produced eggs with high hatching success. Overall, these results indicate that Acartia sp. could be affected by projected near-future CO2 levels.

  16. Illinois Occupational Skill Standards: Plastics Molding Cluster.

    ERIC Educational Resources Information Center

    Illinois Occupational Skill Standards and Credentialing Council, Carbondale.

    This document, which is intended to serve as a guide for work force preparation program providers, details the Illinois occupational skill standards for programs preparing students for employment in jobs in the plastics molding industry. Agency partners involved in this project include: the Illinois State Board of Education, Illinois Community…

  17. Durability of wood-plastic composite lumber

    Treesearch

    Rebecca E. Ibach

    2010-01-01

    Wood-plastic composite (WPC) lumber has been marketed as a low-maintenance, high-durability product. Retail sales in the United States were slightly less than $1 billion in 2008. Applications include docking, railing, windows, doors, fencing, siding, moldings, landscape timbers, car interior parts, and furniture. The majority of these products are used outdoors and...

  18. Effects of morphine on brain plasticity.

    PubMed

    Beltrán-Campos, V; Silva-Vera, M; García-Campos, M L; Díaz-Cintra, S

    2015-04-01

    Morphine shares with other opiates and drugs of abuse the ability to modify the plasticity of brain areas that regulate the morphology of dendrites and spines, which are the primary sites of excitatory synapses in regions of the brain involved in incentive motivation, rewards, and learning. In this review we discuss the impact of morphine use during the prenatal period of brain development and its long-term consequences in murines, and then link those consequences to similar effects occurring in human neonates and adults. Repeated exposure to morphine as treatment for pain in terminally ill patients produces long-term changes in the density of postsynaptic sites (dendrites and spines) in sensitive areas of the brain, such as the prefrontal cortex, the limbic system (hippocampus, amygdala), and caudate nuclei and nucleus accumbens. This article reviews the cellular mechanisms and receptors involved, primarily dopaminergic and glutamatergic receptors, as well as synaptic plasticity brought about by changes in dendritic spines in these areas. The actions of morphine on both developing and adult brains produce alterations in the plasticity of excitatory postsynaptic sites of the brain areas involved in limbic system functions (reward and learning). Doctors need further studies on plasticity in dendrites and spines and on signaling molecules, such as calcium, in order to improve treatments for addiction. Copyright © 2014 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  19. Plastic-Sealed Hybrid Power Circuit Package

    NASA Technical Reports Server (NTRS)

    Miller, W. N.; Gray, O. E.

    1983-01-01

    Proposed design for hybrid high-voltage power-circuit package uses molded plastic for hermetic sealing instead of glass-to-metal seal. New package used to house high-voltage regulators and solid-state switches for applications in aircraft, electric automobiles, industrial equipment, satellites, solarcell arrays, and other equipment in extreme environments.

  20. Design principles of electrical synaptic plasticity.

    PubMed

    O'Brien, John

    2017-09-08

    Essentially all animals with nervous systems utilize electrical synapses as a core element of communication. Electrical synapses, formed by gap junctions between neurons, provide rapid, bidirectional communication that accomplishes tasks distinct from and complementary to chemical synapses. These include coordination of neuron activity, suppression of voltage noise, establishment of electrical pathways that define circuits, and modulation of high order network behavior. In keeping with the omnipresent demand to alter neural network function in order to respond to environmental cues and perform tasks, electrical synapses exhibit extensive plasticity. In some networks, this plasticity can have dramatic effects that completely remodel circuits or remove the influence of certain cell types from networks. Electrical synaptic plasticity occurs on three distinct time scales, ranging from milliseconds to days, with different mechanisms accounting for each. This essay highlights principles that dictate the properties of electrical coupling within networks and the plasticity of the electrical synapses, drawing examples extensively from retinal networks. Copyright © 2017 The Author. Published by Elsevier B.V. All rights reserved.

  1. [Application of thermosetting plastics to eliminate undercuts].

    PubMed

    Bielawski, T

    1989-01-01

    The author proposes to utilize the properties of thermosetting plastics used in other fields to use them in prosthetics in order to eliminate undercuts. Application of extra equipment in claspograph in the form of studs of three dimension makes formation of undercuts' blockade easier improving the result of work at the same time.

  2. Plastic Encapsulated Microcircuits (PEMs) Reliability Guide

    NASA Technical Reports Server (NTRS)

    Sandor, M.

    2000-01-01

    It is reported by some users and has been demonstrated by others via testing and qualification that the quality and reliability of plastic-encapsulated microcircuits (PEMs) manufactured today are excellent in commercial applications and closely equivalent, and in some cases superior to their hemetic counterparts.

  3. Plastic Tubing and Maple Syrup Quality

    Treesearch

    Russell S. Walters; Harry W. Yawney

    1978-01-01

    Maple syrup made from sap collected using improperly or carelessly installed plastic pipelines varied more in color from day to day, and was more often darker in color, than sap collected from either the property installed pipeline or clean, frequently emptied galvanized buckets. Use of both properly installed tubing and buckets, following recommended procedures,...

  4. Durability of Capped Wood Plastic Composites

    Treesearch

    Mark Mankowski; Mark J. Manning; Damien P. Slowik

    2015-01-01

    Manufacturers of wood plastic composites (WPCs) have recently introduced capped decking to their product lines. These new materials have begun to take market share from the previous generation of uncapped products that possessed a homogenous composition throughout the thickness of their cross-section. These capped offerings have been introduced with claims that the...

  5. Thermally stable, plastic-bonded explosives

    DOEpatents

    Benziger, Theodore M.

    1979-01-01

    By use of an appropriate thermoplastic rubber as the binder, the thermal stability and thermal stress characteristics of plastic-bonded explosives may be greatly improved. In particular, an HMX-based explosive composition using an oil-extended styrene-ethylenebutylene-styrene block copolymer as the binder exhibits high explosive energy and thermal stability and good handling safety and physical properties.

  6. Monopole track characteristics in plastic detectors

    NASA Technical Reports Server (NTRS)

    Ahlen, S. P.

    1975-01-01

    Total and restricted energy loss rates were calculated for magnetic monopoles of charge g = 137 e in Lexan polycarbonate. Range-energy curves are also presented. The restricted energy loss model is used to estimate the appearance of a monopole track in plastic detectors. These results should be useful for the design and analysis of monopole experiments.

  7. Sustainable harvest: managing plasticity for resilient crops

    PubMed Central

    Bloomfield, Justin A; Rose, Terry J; King, Graham J

    2014-01-01

    Maintaining crop production to feed a growing world population is a major challenge for this period of rapid global climate change. No consistent conceptual or experimental framework for crop plants integrates information at the levels of genome regulation, metabolism, physiology and response to growing environment. An important role for plasticity in plants is assisting in homeostasis in response to variable environmental conditions. Here, we outline how plant plasticity is facilitated by epigenetic processes that modulate chromatin through dynamic changes in DNA methylation, histone variants, small RNAs and transposable elements. We present examples of plant plasticity in the context of epigenetic regulation of developmental phases and transitions and map these onto the key stages of crop establishment, growth, floral initiation, pollination, seed set and maturation of harvestable product. In particular, we consider how feedback loops of environmental signals and plant nutrition affect plant ontogeny. Recent advances in understanding epigenetic processes enable us to take a fresh look at the crosstalk between regulatory systems that confer plasticity in the context of crop development. We propose that these insights into genotype × environment (G × E) interaction should underpin development of new crop management strategies, both in terms of information-led agronomy and in recognizing the role of epigenetic variation in crop breeding. PMID:24891039

  8. Amphibious fishes: evolution and phenotypic plasticity.

    PubMed

    Wright, Patricia A; Turko, Andy J

    2016-08-01

    Amphibious fishes spend part of their life in terrestrial habitats. The ability to tolerate life on land has evolved independently many times, with more than 200 extant species of amphibious fishes spanning 17 orders now reported. Many adaptations for life out of water have been described in the literature, and adaptive phenotypic plasticity may play an equally important role in promoting favourable matches between the terrestrial habitat and behavioural, physiological, biochemical and morphological characteristics. Amphibious fishes living at the interface of two very different environments must respond to issues relating to buoyancy/gravity, hydration/desiccation, low/high O2 availability, low/high CO2 accumulation and high/low NH3 solubility each time they traverse the air-water interface. Here, we review the literature for examples of plastic traits associated with the response to each of these challenges. Because there is evidence that phenotypic plasticity can facilitate the evolution of fixed traits in general, we summarize the types of investigations needed to more fully determine whether plasticity in extant amphibious fishes can provide indications of the strategies used during the evolution of terrestriality in tetrapods. © 2016. Published by The Company of Biologists Ltd.

  9. Human Maternal Brain Plasticity: Adaptation to Parenting

    ERIC Educational Resources Information Center

    Kim, Pilyoung

    2016-01-01

    New mothers undergo dynamic neural changes that support positive adaptation to parenting and the development of mother-infant relationships. In this article, I review important psychological adaptations that mothers experience during pregnancy and the early postpartum period. I then review evidence of structural and functional plasticity in human…

  10. Catalytic Pyrolysis of Waste Plastic Mixture

    NASA Astrophysics Data System (ADS)

    Sembiring, Ferdianta; Wahyu Purnomo, Chandra; Purwono, Suryo

    2018-03-01

    Inorganic waste especially plastics still become a major problem in many places. Low biodegradability of this materials causes the effort in recycling become very difficult. Most of the municipal solid waste (MSW) recycling facilities in developing country only use composting method to recover the organic fraction of the waste, while the inorganic fraction is still untreated. By pyrolysis, plastic waste can be treated to produce liquid fuels, flammable gas and chars. Reduction in volume and utilization of the liquid and gas as fuel are the major benefits of the process. By heat integration actually this process can become a self-sufficient system in terms of energy demand. However, the drawback of this process is usually due to the diverse type of plastic in the MSW creating low grade of liquid fuel and harmful gases. In this study, the mixture of plastics i.e. polypropylene (PP) and polyethylene terephthalate (PET) is treated using pyrolysis with catalyst in several operating temperature. PET is problematic to be treated using pyrolysis due to wax-like byproduct in liquid which may cause pipe clogging. The catalyst is the mixture of natural zeolite and bentonite which is able to handle PP and PET mixture feed to produce high grade liquid fuels in terms of calorific value and other fuel properties.

  11. Recombination rate plasticity: revealing mechanisms by design

    PubMed Central

    Sefick, Stephen; Rushton, Chase

    2017-01-01

    For over a century, scientists have known that meiotic recombination rates can vary considerably among individuals, and that environmental conditions can modify recombination rates relative to the background. A variety of external and intrinsic factors such as temperature, age, sex and starvation can elicit ‘plastic’ responses in recombination rate. The influence of recombination rate plasticity on genetic diversity of the next generation has interesting and important implications for how populations evolve. Further, many questions remain regarding the mechanisms and molecular processes that contribute to recombination rate plasticity. Here, we review 100 years of experimental work on recombination rate plasticity conducted in Drosophila melanogaster. We categorize this work into four major classes of experimental designs, which we describe via classic studies in D. melanogaster. Based on these studies, we highlight molecular mechanisms that are supported by experimental results and relate these findings to studies in other systems. We synthesize lessons learned from this model system into experimental guidelines for using recent advances in genotyping technologies, to study recombination rate plasticity in non-model organisms. Specifically, we recommend (1) using fine-scale genome-wide markers, (2) collecting time-course data, (3) including crossover distribution measurements, and (4) using mixed effects models to analyse results. To illustrate this approach, we present an application adhering to these guidelines from empirical work we conducted in Drosophila pseudoobscura. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’. PMID:29109222

  12. Elastic-plastic analysis of AS4/PEEK composite laminate using a one-parameter plasticity model

    NASA Technical Reports Server (NTRS)

    Sun, C. T.; Yoon, K. J.

    1992-01-01

    A one-parameter plasticity model was shown to adequately describe the plastic deformation of AS4/PEEK (APC-2) unidirectional thermoplastic composite. This model was verified further for unidirectional and laminated composite panels with and without a hole. The elastic-plastic stress-strain relations of coupon specimens were measured and compared with those predicted by the finite element analysis using the one-parameter plasticity model. The results show that the one-parameter plasticity model is suitable for the analysis of elastic-plastic deformation of AS4/PEEK composite laminates.

  13. [The role of balneology in plastic surgery].

    PubMed

    Correia, N; Binet, A; Caliot, J; Poli Merol, M-L; Bodin, F; François-Fiquet, C

    2016-02-01

    Balneology can be part of the plastic surgery care sector. The objectives of this study were firstly to the state of knowledge about the hydrotherapy and specify the place reserved for hydrotherapy by surgeons as an adjunct in plastic and reconstructive surgery (adult and child). Multicentric national study by poll (Google Drive®) focused at plastic and/or pediatric surgeons. The following information was analyzed: frequency, timing of prescription, indications, the surgeon's feelings towards hydrotherapy and the differences between adult's and children's prescriptions. Fifty-four teams were contacted: 22 responses were received (15 "adult" plastic surgeons, 9 "pediatric" plastic surgeons, 6 pediatric surgeons, with 12 out of 22 working with burnt patients). Eighteen out of 22 prescribed hydrotherapy. Twenty out of 22 thought that hydrotherapy had a role as adjuvant therapy in plastic surgery. The indications were: burns (11/20), skin-graft hypertrophy (10/20), inflammatory and pruritic scar and cutaneous trophic disorders (9/20), psychological (3/20), retractions (2/20), weight loss and smoking (1/20). The timing of the prescription was: < 3 months (2/20), < 6 months (7/20), > 6 months and < 1 year (15/20), > 1 year (8/20) after surgery/trauma. Twenty out of 22 found a beneficial effect: physical (19/20): reduction of inflammatory signs, pruritus and pain, scar maturation, skin thinning improvement; psychological (14/20): positive for patient/family. Five out of 17 made the difference between child/adult, 10/17 made no difference but only treated adults or children. The respondents in the study are probably more sensitive to the effects of hydrotherapy that non-respondents. It is difficult to assess the real impact of hydrotherapy in plastic surgery because distinguishing spontaneous favorable evolution of a scar from one only due to the hydrotherapy or multidisciplinary management is difficult. However, hydrotherapy seems to have its role among multidisciplinary

  14. Developmental Plasticity and Language: A Comparative Perspective.

    PubMed

    Griebel, Ulrike; Pepperberg, Irene M; Oller, D Kimbrough

    2016-04-01

    The growing field of evo-devo is increasingly demonstrating the complexity of steps involved in genetic, intracellular regulatory, and extracellular environmental control of the development of phenotypes. A key result of such work is an account for the remarkable plasticity of organismal form in many species based on relatively minor changes in regulation of highly conserved genes and genetic processes. Accounting for behavioral plasticity is of similar potential interest but has received far less attention. Of particular interest is plasticity in communication systems, where human language represents an ultimate target for research. The present paper considers plasticity of language capabilities in a comparative framework, focusing attention on examples of a remarkable fact: Whereas there exist design features of mature human language that have never been observed to occur in non-humans in the wild, many of these features can be developed to notable extents when non-humans are enculturated through human training (especially with intensive social interaction). These examples of enculturated developmental plasticity across extremely diverse taxa suggest, consistent with the evo-devo theme of highly conserved processes in evolution, that human language is founded in part on cognitive capabilities that are indeed ancient and that even modern humans show self-organized emergence of many language capabilities in the context of rich enculturation, built on the special social/ecological history of the hominin line. Human culture can thus be seen as a regulatory system encouraging language development in the context of a cognitive background with many highly conserved features. Copyright © 2016 Cognitive Science Society, Inc.

  15. ["Plastic lung". Broncho-pulmonary pathology related to plastics (author's transl)].

    PubMed

    Anthoine, D; Martinet, Y; Zuck, P; Peiffer, G; Dangelzer, J; Lamy, P

    1980-01-01

    Plastics can induce three main groups of respiratory accidents.--Acute and subacute intoxications related to the inhalation of volatil substances from decomposing plastics (mostly during burning and pyrolysis) or on the contrary during synthesis. They are accidental chemical broncho-pneumopathies (acute tracheo-bronchitis and pulmonary edema).--Chronic broncho-pneumopathies following repeated inhalation of dusts or suspension of plastics: pneumoconioses and thesaurismoses leading to pulmonary fibrosis.--Broncho-pneumopathies related to the irritant and sensitizing action of some components of plastics: professional asthma and sensitization pneumopathies. Diagnosis of such diseases therefore imposes a careful study of working conditions. Proof rests on two arguments:--curing by risk eviction;--analysis of the products in order to reveal their toxicity.

  16. Hebbian Wiring Plasticity Generates Efficient Network Structures for Robust Inference with Synaptic Weight Plasticity

    PubMed Central

    Hiratani, Naoki; Fukai, Tomoki

    2016-01-01

    In the adult mammalian cortex, a small fraction of spines are created and eliminated every day, and the resultant synaptic connection structure is highly nonrandom, even in local circuits. However, it remains unknown whether a particular synaptic connection structure is functionally advantageous in local circuits, and why creation and elimination of synaptic connections is necessary in addition to rich synaptic weight plasticity. To answer these questions, we studied an inference task model through theoretical and numerical analyses. We demonstrate that a robustly beneficial network structure naturally emerges by combining Hebbian-type synaptic weight plasticity and wiring plasticity. Especially in a sparsely connected network, wiring plasticity achieves reliable computation by enabling efficient information transmission. Furthermore, the proposed rule reproduces experimental observed correlation between spine dynamics and task performance. PMID:27303271

  17. Plastic bag clip discovered in partial colectomy accompanying proposal for phylogenic plastic bag clip classification

    PubMed Central

    Lehmer, Larisa M; Ragsdale, Bruce D; Daniel, John; Hayashi, Edwin; Kvalstad, Robert

    2011-01-01

    A plastic bag clip was incidentally found anchored in the mucosa of a partial colectomy specimen 2.6 cm proximal to a ruptured diverticulum for which the patient, a mentally retarded, diabetic, 58-year-old man, underwent surgery. Over 20 cases of accidental ingestion of plastic bag clips have been published. Known complications include small bowel perforation, obstruction, dysphagia, gastrointestinal bleeding and colonic impaction. Preoperative diagnosis of plastic clips lodged in the gastrointestinal tract is frustrated due to radiographic translucency. This occult threat could likely be prevented by the design of gastrointestinally safe, plastic-bag-sealing devices. Presented here is a morphologically based classification of bag clips as a possible guide for determining the most hazardous varieties and to aid further discussions of their impact on health. PMID:22679182

  18. Factors influencing the detection of beach plastic debris.

    PubMed

    Lavers, Jennifer L; Oppel, Steffen; Bond, Alexander L

    2016-08-01

    Marine plastic pollution is a global problem with considerable ecological and economic consequences. Quantifying the amount of plastic in the ocean has been facilitated by surveys of accumulated plastic on beaches, but existing monitoring programmes assume the proportion of plastic detected during beach surveys is constant across time and space. Here we use a multi-observer experiment to assess what proportion of small plastic fragments is missed routinely by observers, and what factors influence the detection probability of different types of plastic. Detection probability across the various types of plastic ranged from 60 to 100%, and varied considerably by observer, observer experience, and biological material present on the beach that could be confused with plastic. Blue fragments had the highest detection probability, while white fragments had the lowest. We recommend long-term monitoring programmes adopt survey designs accounting for imperfect detection or at least assess the proportion of fragments missed by observers. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Linking plastic ingestion research with marine wildlife conservation.

    PubMed

    Avery-Gomm, Stephanie; Borrelle, Stephanie B; Provencher, Jennifer F

    2018-05-16

    Plastic is an increasingly pervasive marine pollutant. Concomitantly, the number of studies documenting plastic ingestion in wildlife is accelerating. Many of these studies aim to provide a baseline against which future levels of plastic ingestion can be compared, and are motivated by an underlying interest in the conservation of their study species and ecosystems. Although this research has helped to raise the profile of plastic as a pollutant of emerging concern, there is a disconnect between research examining plastic pollution and wildlife conservation. We present ideas to further discussion about how plastic ingestion research could benefit wildlife conservation by prioritising studies that elucidates the significance of plastic pollution as a population-level threat, identifies vulnerable populations, and evaluates strategies for mitigating impacts. The benefit of plastic ingestion research to marine wildlife can be improved by establishing a clearer understanding of how discoveries will be integrated into conservation and policy actions. Copyright © 2018. Published by Elsevier B.V.

  20. 49 CFR 192.123 - Design limitations for plastic pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... formula under § 192.121 is determined. (ii) For reinforced thermosetting plastic pipe, 150 °F (66 °C). (c...) The wall thickness for reinforced thermosetting plastic pipe may not be less than that listed in the...