WorldWideScience

Sample records for monte-carlo-based phase retardation

  1. Monte Carlo based investigation of Berry phase for depth resolved characterization of biomedical scattering samples

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Justin S [ORNL; John, Dwayne O [ORNL; Koju, Vijay [ORNL

    2015-01-01

    The propagation of light in turbid media is an active area of research with relevance to numerous investigational fields, e.g., biomedical diagnostics and therapeutics. The statistical random-walk nature of photon propagation through turbid media is ideal for computational based modeling and simulation. Ready access to super computing resources provide a means for attaining brute force solutions to stochastic light-matter interactions entailing scattering by facilitating timely propagation of sufficient (>10million) photons while tracking characteristic parameters based on the incorporated physics of the problem. One such model that works well for isotropic but fails for anisotropic scatter, which is the case for many biomedical sample scattering problems, is the diffusion approximation. In this report, we address this by utilizing Berry phase (BP) evolution as a means for capturing anisotropic scattering characteristics of samples in the preceding depth where the diffusion approximation fails. We extend the polarization sensitive Monte Carlo method of Ramella-Roman, et al.,1 to include the computationally intensive tracking of photon trajectory in addition to polarization state at every scattering event. To speed-up the computations, which entail the appropriate rotations of reference frames, the code was parallelized using OpenMP. The results presented reveal that BP is strongly correlated to the photon penetration depth, thus potentiating the possibility of polarimetric depth resolved characterization of highly scattering samples, e.g., biological tissues.

  2. Quantitative Monte Carlo-based holmium-166 SPECT reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Elschot, Mattijs; Smits, Maarten L. J.; Nijsen, Johannes F. W.; Lam, Marnix G. E. H.; Zonnenberg, Bernard A.; Bosch, Maurice A. A. J. van den; Jong, Hugo W. A. M. de [Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Viergever, Max A. [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2013-11-15

    Purpose: Quantitative imaging of the radionuclide distribution is of increasing interest for microsphere radioembolization (RE) of liver malignancies, to aid treatment planning and dosimetry. For this purpose, holmium-166 ({sup 166}Ho) microspheres have been developed, which can be visualized with a gamma camera. The objective of this work is to develop and evaluate a new reconstruction method for quantitative {sup 166}Ho SPECT, including Monte Carlo-based modeling of photon contributions from the full energy spectrum.Methods: A fast Monte Carlo (MC) simulator was developed for simulation of {sup 166}Ho projection images and incorporated in a statistical reconstruction algorithm (SPECT-fMC). Photon scatter and attenuation for all photons sampled from the full {sup 166}Ho energy spectrum were modeled during reconstruction by Monte Carlo simulations. The energy- and distance-dependent collimator-detector response was modeled using precalculated convolution kernels. Phantom experiments were performed to quantitatively evaluate image contrast, image noise, count errors, and activity recovery coefficients (ARCs) of SPECT-fMC in comparison with those of an energy window-based method for correction of down-scattered high-energy photons (SPECT-DSW) and a previously presented hybrid method that combines MC simulation of photopeak scatter with energy window-based estimation of down-scattered high-energy contributions (SPECT-ppMC+DSW). Additionally, the impact of SPECT-fMC on whole-body recovered activities (A{sup est}) and estimated radiation absorbed doses was evaluated using clinical SPECT data of six {sup 166}Ho RE patients.Results: At the same noise level, SPECT-fMC images showed substantially higher contrast than SPECT-DSW and SPECT-ppMC+DSW in spheres ≥17 mm in diameter. The count error was reduced from 29% (SPECT-DSW) and 25% (SPECT-ppMC+DSW) to 12% (SPECT-fMC). ARCs in five spherical volumes of 1.96–106.21 ml were improved from 32%–63% (SPECT-DSW) and 50%–80

  3. GPU-Monte Carlo based fast IMRT plan optimization

    Directory of Open Access Journals (Sweden)

    Yongbao Li

    2014-03-01

    , Shi F, Jiang S, Jia X. GPU-Monte Carlo based fast IMRT plan optimization. Int J Cancer Ther Oncol 2014; 2(2:020244. DOI: 10.14319/ijcto.0202.44

  4. Development of a Monte-Carlo based method for calculating the effect of stationary fluctuations

    DEFF Research Database (Denmark)

    Pettersen, E. E.; Demazire, C.; Jareteg, K.

    2015-01-01

    that corresponds to the real part of the neutron balance, and one that corresponds to the imaginary part. The two equivalent problems are in nature similar to two subcritical systems driven by external neutron sources, and can thus be treated as such in a Monte Carlo framework. The definition of these two...... of light water reactor conditions in an infinite lattice of fuel pins surrounded by water. The test case highlights flux gradients that are steeper in the Monte Carlo-based transport solution than in the diffusion-based solution. Compared to other Monte Carlo-based methods earlier proposed for carrying out...

  5. MCHITS: Monte Carlo based Method for Hyperlink Induced Topic Search on Networks

    Directory of Open Access Journals (Sweden)

    Zhaoyan Jin

    2013-10-01

    Full Text Available Hyperlink Induced Topic Search (HITS is the most authoritative and most widely used personalized ranking algorithm on networks. The HITS algorithm ranks nodes on networks according to power iteration, and has high complexity of computation. This paper models the HITS algorithm with the Monte Carlo method, and proposes Monte Carlo based algorithms for the HITS computation. Theoretical analysis and experiments show that the Monte Carlo based approximate computing of the HITS ranking reduces computing resources a lot while keeping higher accuracy, and is significantly better than related works

  6. Monte Carlo based treatment planning systems for Boron Neutron Capture Therapy in Petten, The Netherlands

    Science.gov (United States)

    Nievaart, V. A.; Daquino, G. G.; Moss, R. L.

    2007-06-01

    Boron Neutron Capture Therapy (BNCT) is a bimodal form of radiotherapy for the treatment of tumour lesions. Since the cancer cells in the treatment volume are targeted with 10B, a higher dose is given to these cancer cells due to the 10B(n,α)7Li reaction, in comparison with the surrounding healthy cells. In Petten (The Netherlands), at the High Flux Reactor, a specially tailored neutron beam has been designed and installed. Over 30 patients have been treated with BNCT in 2 clinical protocols: a phase I study for the treatment of glioblastoma multiforme and a phase II study on the treatment of malignant melanoma. Furthermore, activities concerning the extra-corporal treatment of metastasis in the liver (from colorectal cancer) are in progress. The irradiation beam at the HFR contains both neutrons and gammas that, together with the complex geometries of both patient and beam set-up, demands for very detailed treatment planning calculations. A well designed Treatment Planning System (TPS) should obey the following general scheme: (1) a pre-processing phase (CT and/or MRI scans to create the geometric solid model, cross-section files for neutrons and/or gammas); (2) calculations (3D radiation transport, estimation of neutron and gamma fluences, macroscopic and microscopic dose); (3) post-processing phase (displaying of the results, iso-doses and -fluences). Treatment planning in BNCT is performed making use of Monte Carlo codes incorporated in a framework, which includes also the pre- and post-processing phases. In particular, the glioblastoma multiforme protocol used BNCT_rtpe, while the melanoma metastases protocol uses NCTPlan. In addition, an ad hoc Positron Emission Tomography (PET) based treatment planning system (BDTPS) has been implemented in order to integrate the real macroscopic boron distribution obtained from PET scanning. BDTPS is patented and uses MCNP as the calculation engine. The precision obtained by the Monte Carlo based TPSs exploited at Petten

  7. Monte Carlo-based Noise Compensation in Coil Intensity Corrected Endorectal MRI

    CERN Document Server

    Lui, Dorothy; Haider, Masoom; Wong, Alexander

    2015-01-01

    Background: Prostate cancer is one of the most common forms of cancer found in males making early diagnosis important. Magnetic resonance imaging (MRI) has been useful in visualizing and localizing tumor candidates and with the use of endorectal coils (ERC), the signal-to-noise ratio (SNR) can be improved. The coils introduce intensity inhomogeneities and the surface coil intensity correction built into MRI scanners is used to reduce these inhomogeneities. However, the correction typically performed at the MRI scanner level leads to noise amplification and noise level variations. Methods: In this study, we introduce a new Monte Carlo-based noise compensation approach for coil intensity corrected endorectal MRI which allows for effective noise compensation and preservation of details within the prostate. The approach accounts for the ERC SNR profile via a spatially-adaptive noise model for correcting non-stationary noise variations. Such a method is useful particularly for improving the image quality of coil i...

  8. New Monte Carlo-based method to evaluate fission fraction uncertainties for the reactor antineutrino experiment

    Science.gov (United States)

    Ma, X. B.; Qiu, R. M.; Chen, Y. X.

    2017-02-01

    Uncertainties regarding fission fractions are essential in understanding antineutrino flux predictions in reactor antineutrino experiments. A new Monte Carlo-based method to evaluate the covariance coefficients between isotopes is proposed. The covariance coefficients are found to vary with reactor burnup and may change from positive to negative because of balance effects in fissioning. For example, between 235U and 239Pu, the covariance coefficient changes from 0.15 to -0.13. Using the equation relating fission fraction and atomic density, consistent uncertainties in the fission fraction and covariance matrix were obtained. The antineutrino flux uncertainty is 0.55%, which does not vary with reactor burnup. The new value is about 8.3% smaller.

  9. Dosimetric validation of a commercial Monte Carlo based IMRT planning system.

    Science.gov (United States)

    Grofsmid, Dennis; Dirkx, Maarten; Marijnissen, Hans; Woudstra, Evert; Heijmen, Ben

    2010-02-01

    Recently a commercial Monte Carlo based IMRT planning system (Monaco version 1.0.0) was released. In this study the dosimetric accuracy of this new planning system was validated. Absolute dose profiles, depth dose curves, and output factors calculated by Monaco were compared with measurements in a water phantom. Different static on-axis and off-axis fields were tested at various source-skin distances for 6, 10, and 18 MV photon beams. Four clinical IMRT plans were evaluated in a water phantom using a linear diode detector array and another six IMRT plans for different tumor sites in solid water using a 2D detector array. In order to evaluate the accuracy of the dose engine near tissue inhomogeneities absolute dose distributions were measured with Gafchromic EBT film in an inhomogeneous slab phantom. For an end-to-end test a four-field IMRT plan was applied to an anthropomorphic lung phantom with a simulated tumor peripherally located in the right lung. Gafchromic EBT film, placed in and around the tumor area, was used to evaluate the dose distribution. Generally, the measured and the calculated dose distributions agreed within 2% dose difference or 2 mm distance-to-agreement. But mainly at interfaces with bone, some larger dose differences could be observed. Based on the results of this study, the authors concluded that the dosimetric accuracy of Monaco is adequate for clinical introduction.

  10. A comprehensive revisit of the ρ meson with improved Monte-Carlo based QCD sum rules

    Science.gov (United States)

    Wang, Qi-Nan; Zhang, Zhu-Feng; Steele, T. G.; Jin, Hong-Ying; Huang, Zhuo-Ran

    2017-07-01

    We improve the Monte-Carlo based QCD sum rules by introducing the rigorous Hölder-inequality-determined sum rule window and a Breit-Wigner type parametrization for the phenomenological spectral function. In this improved sum rule analysis methodology, the sum rule analysis window can be determined without any assumptions on OPE convergence or the QCD continuum. Therefore, an unbiased prediction can be obtained for the phenomenological parameters (the hadronic mass and width etc.). We test the new approach in the ρ meson channel with re-examination and inclusion of α s corrections to dimension-4 condensates in the OPE. We obtain results highly consistent with experimental values. We also discuss the possible extension of this method to some other channels. Supported by NSFC (11175153, 11205093, 11347020), Open Foundation of the Most Important Subjects of Zhejiang Province, and K. C. Wong Magna Fund in Ningbo University, TGS is Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), Z. F. Zhang and Z. R. Huang are Grateful to the University of Saskatchewan for its Warm Hospitality

  11. A Monte-Carlo based model of the AX-PET demonstrator and its experimental validation.

    Science.gov (United States)

    Solevi, P; Oliver, J F; Gillam, J E; Bolle, E; Casella, C; Chesi, E; De Leo, R; Dissertori, G; Fanti, V; Heller, M; Lai, M; Lustermann, W; Nappi, E; Pauss, F; Rudge, A; Ruotsalainen, U; Schinzel, D; Schneider, T; Séguinot, J; Stapnes, S; Weilhammer, P; Tuna, U; Joram, C; Rafecas, M

    2013-08-21

    AX-PET is a novel PET detector based on axially oriented crystals and orthogonal wavelength shifter (WLS) strips, both individually read out by silicon photo-multipliers. Its design decouples sensitivity and spatial resolution, by reducing the parallax error due to the layered arrangement of the crystals. Additionally the granularity of AX-PET enhances the capability to track photons within the detector yielding a large fraction of inter-crystal scatter events. These events, if properly processed, can be included in the reconstruction stage further increasing the sensitivity. Its unique features require dedicated Monte-Carlo simulations, enabling the development of the device, interpreting data and allowing the development of reconstruction codes. At the same time the non-conventional design of AX-PET poses several challenges to the simulation and modeling tasks, mostly related to the light transport and distribution within the crystals and WLS strips, as well as the electronics readout. In this work we present a hybrid simulation tool based on an analytical model and a Monte-Carlo based description of the AX-PET demonstrator. It was extensively validated against experimental data, providing excellent agreement.

  12. A Monte-Carlo based extension of the Meteor Orbit and Trajectory Software (MOTS) for computations of orbital elements

    Science.gov (United States)

    Albin, T.; Koschny, D.; Soja, R.; Srama, R.; Poppe, B.

    2016-01-01

    The Canary Islands Long-Baseline Observatory (CILBO) is a double station meteor camera system (Koschny et al., 2013; Koschny et al., 2014) that consists of 5 cameras. The two cameras considered in this report are ICC7 and ICC9, and are installed on Tenerife and La Palma. They point to the same atmospheric volume between both islands allowing stereoscopic observation of meteors. Since its installation in 2011 and the start of operation in 2012 CILBO has detected over 15000 simultaneously observed meteors. Koschny and Diaz (2002) developed the Meteor Orbit and Trajectory Software (MOTS) to compute the trajectory of such meteors. The software uses the astrometric data from the detection software MetRec (Molau, 1998) and determines the trajectory in geodetic coordinates. This work presents a Monte-Carlo based extension of the MOTS code to compute the orbital elements of simultaneously detected meteors by CILBO.

  13. Using a Monte-Carlo-based approach to evaluate the uncertainty on fringe projection technique

    CERN Document Server

    Molimard, Jérôme

    2013-01-01

    A complete uncertainty analysis on a given fringe projection set-up has been performed using Monte-Carlo approach. In particular the calibration procedure is taken into account. Two applications are given: at a macroscopic scale, phase noise is predominant whilst at microscopic scale, both phase noise and calibration errors are important. Finally, uncertainty found at macroscopic scale is close to some experimental tests (~100 {\\mu}m).

  14. A Monte Carlo-based radiation safety assessment for astronauts in an environment with confined magnetic field shielding.

    Science.gov (United States)

    Geng, Changran; Tang, Xiaobin; Gong, Chunhui; Guan, Fada; Johns, Jesse; Shu, Diyun; Chen, Da

    2015-12-01

    The active shielding technique has great potential for radiation protection in space exploration because it has the advantage of a significant mass saving compared with the passive shielding technique. This paper demonstrates a Monte Carlo-based approach to evaluating the shielding effectiveness of the active shielding technique using confined magnetic fields (CMFs). The International Commission on Radiological Protection reference anthropomorphic phantom, as well as the toroidal CMF, was modeled using the Monte Carlo toolkit Geant4. The penetrating primary particle fluence, organ-specific dose equivalent, and male effective dose were calculated for particles in galactic cosmic radiation (GCR) and solar particle events (SPEs). Results show that the SPE protons can be easily shielded against, even almost completely deflected, by the toroidal magnetic field. GCR particles can also be more effectively shielded against by increasing the magnetic field strength. Our results also show that the introduction of a structural Al wall in the CMF did not provide additional shielding for GCR; in fact it can weaken the total shielding effect of the CMF. This study demonstrated the feasibility of accurately determining the radiation field inside the environment and evaluating the organ dose equivalents for astronauts under active shielding using the CMF.

  15. Reconciliation between experimental and Monte Carlo-based simulation of the pore size distribution in mesoporous silicon.

    Science.gov (United States)

    Tadvani, Jalil Khajepour; Falamaki, Cavus

    2008-07-23

    It is demonstrated for the first time that mesoporous PS structures obtained by the electrochemical etching of p(+)(100) oriented silicon wafers might assume the peculiarity of invariance of the first peak positions in their pore size distribution curves, albeit for current densities far from the electropolishing region and at constant electrolyte composition. A new Monte Carlo-based simulation model is presented that predicts reasonably the pore size distribution of the PS layers and the observed invariance of peak position with respect to changes in current density. The main highlight of the new model is the introduction of a 'light avalanche breakdown' process in a mathematical fashion. The model is also able to predict an absolute value of 4.23 Å for the smallest pore created experimentally. It is discussed that the latter value has an exact physical meaning: it corresponds with great accuracy to the width of a void created on the surface due to the exclusion of one Si atom.

  16. Reconciliation between experimental and Monte Carlo-based simulation of the pore size distribution in mesoporous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Tadvani, Jalil Khajepour [Ceramics Department, Materials and Energy Research Center, PO Box 14155-4777, Tehran (Iran, Islamic Republic of); Falamaki, Cavus [Chemical Engineering Department, Amirkabir University of Technology, Hafez Avenue, PO Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2008-07-23

    It is demonstrated for the first time that mesoporous PS structures obtained by the electrochemical etching of p{sup +}(100) oriented silicon wafers might assume the peculiarity of invariance of the first peak positions in their pore size distribution curves, albeit for current densities far from the electropolishing region and at constant electrolyte composition. A new Monte Carlo-based simulation model is presented that predicts reasonably the pore size distribution of the PS layers and the observed invariance of peak position with respect to changes in current density. The main highlight of the new model is the introduction of a 'light avalanche breakdown' process in a mathematical fashion. The model is also able to predict an absolute value of 4.23 A for the smallest pore created experimentally. It is discussed that the latter value has an exact physical meaning: it corresponds with great accuracy to the width of a void created on the surface due to the exclusion of one Si atom.

  17. Monte Carlo based verification of a beam model used in a treatment planning system

    Science.gov (United States)

    Wieslander, E.; Knöös, T.

    2008-02-01

    Modern treatment planning systems (TPSs) usually separate the dose modelling into a beam modelling phase, describing the beam exiting the accelerator, followed by a subsequent dose calculation in the patient. The aim of this work is to use the Monte Carlo code system EGSnrc to study the modelling of head scatter as well as the transmission through multi-leaf collimator (MLC) and diaphragms in the beam model used in a commercial TPS (MasterPlan, Nucletron B.V.). An Elekta Precise linear accelerator equipped with an MLC has been modelled in BEAMnrc, based on available information from the vendor regarding the material and geometry of the treatment head. The collimation in the MLC direction consists of leafs which are complemented with a backup diaphragm. The characteristics of the electron beam, i.e., energy and spot size, impinging on the target have been tuned to match measured data. Phase spaces from simulations of the treatment head are used to extract the scatter from, e.g., the flattening filter and the collimating structures. Similar data for the source models used in the TPS are extracted from the treatment planning system, thus a comprehensive analysis is possible. Simulations in a water phantom, with DOSXYZnrc, are also used to study the modelling of the MLC and the diaphragms by the TPS. The results from this study will be helpful to understand the limitations of the model in the TPS and provide knowledge for further improvements of the TPS source modelling.

  18. SU-E-T-761: TOMOMC, A Monte Carlo-Based Planning VerificationTool for Helical Tomotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chibani, O; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

    2015-06-15

    Purpose: Present a new Monte Carlo code (TOMOMC) to calculate 3D dose distributions for patients undergoing helical tomotherapy treatments. TOMOMC performs CT-based dose calculations using the actual dynamic variables of the machine (couch motion, gantry rotation, and MLC sequences). Methods: TOMOMC is based on the GEPTS (Gama Electron and Positron Transport System) general-purpose Monte Carlo system (Chibani and Li, Med. Phys. 29, 2002, 835). First, beam models for the Hi-Art Tomotherpy machine were developed for the different beam widths (1, 2.5 and 5 cm). The beam model accounts for the exact geometry and composition of the different components of the linac head (target, primary collimator, jaws and MLCs). The beams models were benchmarked by comparing calculated Pdds and lateral/transversal dose profiles with ionization chamber measurements in water. See figures 1–3. The MLC model was tuned in such a way that tongue and groove effect, inter-leaf and intra-leaf transmission are modeled correctly. See figure 4. Results: By simulating the exact patient anatomy and the actual treatment delivery conditions (couch motion, gantry rotation and MLC sinogram), TOMOMC is able to calculate the 3D patient dose distribution which is in principal more accurate than the one from the treatment planning system (TPS) since it relies on the Monte Carlo method (gold standard). Dose volume parameters based on the Monte Carlo dose distribution can also be compared to those produced by the TPS. Attached figures show isodose lines for a H&N patient calculated by TOMOMC (transverse and sagittal views). Analysis of differences between TOMOMC and TPS is an ongoing work for different anatomic sites. Conclusion: A new Monte Carlo code (TOMOMC) was developed for Tomotherapy patient-specific QA. The next step in this project is implementing GPU computing to speed up Monte Carlo simulation and make Monte Carlo-based treatment verification a practical solution.

  19. Assessment of parameter uncertainty in hydrological model using a Markov-Chain-Monte-Carlo-based multilevel-factorial-analysis method

    Science.gov (United States)

    Zhang, Junlong; Li, Yongping; Huang, Guohe; Chen, Xi; Bao, Anming

    2016-07-01

    Without a realistic assessment of parameter uncertainty, decision makers may encounter difficulties in accurately describing hydrologic processes and assessing relationships between model parameters and watershed characteristics. In this study, a Markov-Chain-Monte-Carlo-based multilevel-factorial-analysis (MCMC-MFA) method is developed, which can not only generate samples of parameters from a well constructed Markov chain and assess parameter uncertainties with straightforward Bayesian inference, but also investigate the individual and interactive effects of multiple parameters on model output through measuring the specific variations of hydrological responses. A case study is conducted for addressing parameter uncertainties in the Kaidu watershed of northwest China. Effects of multiple parameters and their interactions are quantitatively investigated using the MCMC-MFA with a three-level factorial experiment (totally 81 runs). A variance-based sensitivity analysis method is used to validate the results of parameters' effects. Results disclose that (i) soil conservation service runoff curve number for moisture condition II (CN2) and fraction of snow volume corresponding to 50% snow cover (SNO50COV) are the most significant factors to hydrological responses, implying that infiltration-excess overland flow and snow water equivalent represent important water input to the hydrological system of the Kaidu watershed; (ii) saturate hydraulic conductivity (SOL_K) and soil evaporation compensation factor (ESCO) have obvious effects on hydrological responses; this implies that the processes of percolation and evaporation would impact hydrological process in this watershed; (iii) the interactions of ESCO and SNO50COV as well as CN2 and SNO50COV have an obvious effect, implying that snow cover can impact the generation of runoff on land surface and the extraction of soil evaporative demand in lower soil layers. These findings can help enhance the hydrological model

  20. An approach to using conventional brachytherapy software for clinical treatment planning of complex, Monte Carlo-based brachytherapy dose distributions

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, Mark J.; Melhus, Christopher S.; Granero, Domingo; Perez-Calatayud, Jose; Ballester, Facundo [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Radiation Oncology Department, Physics Section, ' ' La Fe' ' University Hospital, Avenida Campanar 21, E-46009 Valencia (Spain); Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, C/Dr. Moliner 50, E-46100 Burjassot, Spain and IFIC (University of Valencia-CSIC), C/Dr. Moliner 50, E-46100 Burjassot (Spain)

    2009-06-15

    dosimetry parameter data {<=}0.1 cm was required, and the virtual brachytherapy source data set included over 5000 data points. On the other hand, the lack of consideration for applicator heterogeneity effect caused conventional dose overestimates exceeding an order of magnitude in regions of clinical interest. This approach is rationalized by the improved dose estimates. In conclusion, a new technique was developed to incorporate complex Monte Carlo-based brachytherapy dose distributions into conventional TPS. These results are generalizable to other brachytherapy source types and other TPS.

  1. Monte Carlo-based interval transformation analysis for multi-criteria decision analysis of groundwater management strategies under uncertain naphthalene concentrations and health risks

    Science.gov (United States)

    Ren, Lixia; He, Li; Lu, Hongwei; Chen, Yizhong

    2016-08-01

    A new Monte Carlo-based interval transformation analysis (MCITA) is used in this study for multi-criteria decision analysis (MCDA) of naphthalene-contaminated groundwater management strategies. The analysis can be conducted when input data such as total cost, contaminant concentration and health risk are represented as intervals. Compared to traditional MCDA methods, MCITA-MCDA has the advantages of (1) dealing with inexactness of input data represented as intervals, (2) mitigating computational time due to the introduction of Monte Carlo sampling method, (3) identifying the most desirable management strategies under data uncertainty. A real-world case study is employed to demonstrate the performance of this method. A set of inexact management alternatives are considered in each duration on the basis of four criteria. Results indicated that the most desirable management strategy lied in action 15 for the 5-year, action 8 for the 10-year, action 12 for the 15-year, and action 2 for the 20-year management.

  2. A hybrid phantom Monte Carlo-based method for historical reconstruction of organ doses in patients treated with cobalt-60 for Hodgkin's lymphoma

    Science.gov (United States)

    Petroccia, Heather; Mendenhall, Nancy; Liu, Chihray; Hammer, Clifford; Culberson, Wesley; Thar, Tim; Mitchell, Tom; Li, Zuofeng; Bolch, Wesley

    2017-08-01

    Historical radiotherapy treatment plans lack 3D images sets required for estimating mean organ doses to patients. Alternatively, Monte Carlo-based models of radiotherapy devices coupled with whole-body computational phantoms can permit estimates of historical in-field and out-of-field organ doses as needed for studies associating radiation exposure and late tissue toxicities. In recreating historical patient treatments with 60Co based systems, the major components to be modeled include the source capsule, surrounding shielding layers, collimators (both fixed and adjustable), and trimmers as needed to vary field size. In this study, a computational model and experimental validation of the Theratron T-1000 are presented. Model validation is based upon in-field commissioning data collected at the University of Florida, published out-of-field data from the British Journal of Radiology (BJR) Supplement 25, and out-of-field measurements performed at the University of Wisconsin’s Accredited Dosimetry Calibration Laboratory (UWADCL). The computational model of the Theratron T-1000 agrees with central axis percentage depth dose data to within 2% for 6  ×  6 to 30  ×  30 cm2 fields. Out-of-field doses were found to vary between 0.6% to 2.4% of central axis dose at 10 cm from field edge and 0.42% to 0.97% of central axis dose at 20 cm from the field edge, all at 5 cm depth. Absolute and relative differences between computed and measured out-of-field doses varied between  ±2.5% and  ±100%, respectively, at distances up to 60 cm from the central axis. The source-term model was subsequently combined with patient-morphometry matched computational hybrid phantoms as a method for estimating in-field and out-of-field organ doses for patients treated for Hodgkin’s Lymphoma. By changing field size and position, and adding patient-specific field shaping blocks, more complex historical treatment set-ups can be to recreated, particularly those

  3. Experimental Component Characterization, Monte-Carlo-Based Image Generation and Source Reconstruction for the Neutron Imaging System of the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, C A; Moran, M J

    2007-08-21

    The Neutron Imaging System (NIS) is one of seven ignition target diagnostics under development for the National Ignition Facility. The NIS is required to record hot-spot (13-15 MeV) and downscattered (6-10 MeV) images with a resolution of 10 microns and a signal-to-noise ratio (SNR) of 10 at the 20% contour. The NIS is a valuable diagnostic since the downscattered neutrons reveal the spatial distribution of the cold fuel during an ignition attempt, providing important information in the case of a failed implosion. The present study explores the parameter space of several line-of-sight (LOS) configurations that could serve as the basis for the final design. Six commercially available organic scintillators were experimentally characterized for their light emission decay profile and neutron sensitivity. The samples showed a long lived decay component that makes direct recording of a downscattered image impossible. The two best candidates for the NIS detector material are: EJ232 (BC422) plastic fibers or capillaries filled with EJ399B. A Monte Carlo-based end-to-end model of the NIS was developed to study the imaging capabilities of several LOS configurations and verify that the recovered sources meet the design requirements. The model includes accurate neutron source distributions, aperture geometries (square pinhole, triangular wedge, mini-penumbral, annular and penumbral), their point spread functions, and a pixelated scintillator detector. The modeling results show that a useful downscattered image can be obtained by recording the primary peak and the downscattered images, and then subtracting a decayed version of the former from the latter. The difference images need to be deconvolved in order to obtain accurate source distributions. The images are processed using a frequency-space modified-regularization algorithm and low-pass filtering. The resolution and SNR of these sources are quantified by using two surrogate sources. The simulations show that all LOS

  4. Foveal phase retardation changes associated with normal aging.

    Science.gov (United States)

    VanNasdale, Dean A; Elsner, Ann E; Hobbs, Timothy; Burns, Stephen A

    2011-11-01

    This study quantified normal age-related changes to the photoreceptor axons in the central macula using the birefringent properties of the Henle fiber layer. A scanning laser polarimeter was used to acquire 15° × 15° macular images in 120 clinically normal subjects, ranging in age from the third decade to the eighth. Raw image data of the macular cross were used to compute phase retardation maps associated with Henle fiber layer. Annular regions of interest ranging from 0.25° to 3° eccentricity and centered on the fovea were used to generate intensity profiles from the phase retardation data, which were then analyzed using sine curve fitting and Fast Fourier Transform (FFT). The amplitude of a 2f sine curve was used as a measure of macular phase retardation magnitude. For FFT analysis, the 2f amplitude, as well as the 4f, were normalized by the remaining FFT components. The amplitude component of the 2f curve fit and the normalized 2f FFT component decreased as a function of age, while the eccentricity of the maximum value for the normalized 2f FFT component increased. The phase retardation changes in the central macula indicate structural alterations in the cone photoreceptor axons near the fovea as a function of age. These changes result in either fewer cone photoreceptors in the central macula, or a change in the orientation of their axons. This large sample size demonstrates systematic changes to the central cone photoreceptor morphology using scanning laser polarimetry.

  5. Inverse modeling of cloud-aerosol interactions -- Part 2: Sensitivity tests on liquid phase clouds using a Markov Chain Monte Carlo based simulation approach

    NARCIS (Netherlands)

    Partridge, D.G.; Vrugt, J.A.; Tunved, P.; Ekman, A.M.L.; Struthers, H.; Sooroshian, A.

    2012-01-01

    This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov chain Monte Carlo (MCMC) algorithm to an adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools t

  6. Inverse modelling of cloud-aerosol interactions – Part 2: Sensitivity tests on liquid phase clouds using a Markov chain Monte Carlo based simulation approach

    Directory of Open Access Journals (Sweden)

    D. G. Partridge

    2012-03-01

    Full Text Available This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov chain Monte Carlo (MCMC algorithm to an adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools to investigate the global sensitivity of a cloud model to input aerosol physiochemical parameters. Using numerically generated cloud droplet number concentration (CDNC distributions (i.e. synthetic data as cloud observations, this inverse modelling framework is shown to successfully estimate the correct calibration parameters, and their underlying posterior probability distribution.

    The employed analysis method provides a new, integrative framework to evaluate the global sensitivity of the derived CDNC distribution to the input parameters describing the lognormal properties of the accumulation mode aerosol and the particle chemistry. To a large extent, results from prior studies are confirmed, but the present study also provides some additional insights. There is a transition in relative sensitivity from very clean marine Arctic conditions where the lognormal aerosol parameters representing the accumulation mode aerosol number concentration and mean radius and are found to be most important for determining the CDNC distribution to very polluted continental environments (aerosol concentration in the accumulation mode >1000 cm−3 where particle chemistry is more important than both number concentration and size of the accumulation mode.

    The competition and compensation between the cloud model input parameters illustrates that if the soluble mass fraction is reduced, the aerosol number concentration, geometric standard deviation and mean radius of the accumulation mode must increase in order to achieve the same CDNC distribution.

    This study demonstrates that inverse modelling provides a flexible, transparent and integrative method for efficiently exploring cloud-aerosol interactions with respect to parameter sensitivity and correlation.

  7. Inverse modeling of cloud-aerosol interactions – Part 2: Sensitivity tests on liquid phase clouds using a Markov Chain Monte Carlo based simulation approach

    Directory of Open Access Journals (Sweden)

    D. G. Partridge

    2011-07-01

    Full Text Available This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov Chain Monte Carlo (MCMC algorithm to a pseudo-adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools to investigate the sensitivity of a cloud model to input aerosol physiochemical parameters. Using synthetic data as observed values of cloud droplet number concentration (CDNC distribution, this inverse modelling framework is shown to successfully converge to the correct calibration parameters.

    The employed analysis method provides a new, integrative framework to evaluate the sensitivity of the derived CDNC distribution to the input parameters describing the lognormal properties of the accumulation mode and the particle chemistry. To a large extent, results from prior studies are confirmed, but the present study also provides some additional insightful findings. There is a clear transition from very clean marine Arctic conditions where the aerosol parameters representing the mean radius and geometric standard deviation of the accumulation mode are found to be most important for determining the CDNC distribution to very polluted continental environments (aerosol concentration in the accumulation mode >1000 cm−3 where particle chemistry is more important than both number concentration and size of the accumulation mode.

    The competition and compensation between the cloud model input parameters illustrate that if the soluble mass fraction is reduced, both the number of particles and geometric standard deviation must increase and the mean radius of the accumulation mode must increase in order to achieve the same CDNC distribution.

    For more polluted aerosol conditions, with a reduction in soluble mass fraction the parameter correlation becomes weaker and more non-linear over the range of possible solutions (indicative of the sensitivity. This indicates that for the cloud parcel model used herein, the relative importance of the soluble mass fraction appears to decrease if the number or geometric standard deviation of the accumulation mode is increased.

    This study demonstrates that inverse modelling provides a flexible, transparent and integrative method for efficiently exploring cloud-aerosol interactions efficiently with respect to parameter sensitivity and correlation.

  8. Design of broad angular phase retarders for the complete polarization analysis of extreme ultraviolet radiation

    Science.gov (United States)

    Lin, Cheng-You; Chen, Shu-Jing; Chen, Zhao-Yang; Ding, Ying-Chun

    2015-11-01

    A method of designing broad angular phase retarders in the extreme ultraviolet (EUV) region is presented. The design is based on a standard Levenberg-Marquardt algorithm combined with a common merit function. Using this method, a series of broad angular EUV phase retarders were designed using aperiodic Mo/Si multilayers. At photon energy of 90 eV, broad angular phase retarders with 30°, 60°, and 90° phase retardations have been realized in the angular range of 39°-51°. By analyzing and comparing the performances of the designed broad angular phase retarders, we found that the Mo/Si multilayer with more layers could obtain higher phase retardation in broader angular range when used to design the broad angular phase retarder. Broad angular phase retarders possess lower sensitivity toward changing incident angle compared with the traditional phase retarders designed with transmission periodic multilayers, and can be used for the polarization control of broad angular EUV sources. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant Nos. JD1517, ZY1349, and 2652014012).

  9. A virtual photon source model of an Elekta linear accelerator with integrated mini MLC for Monte Carlo based IMRT dose calculation.

    Science.gov (United States)

    Sikora, M; Dohm, O; Alber, M

    2007-08-07

    A dedicated, efficient Monte Carlo (MC) accelerator head model for intensity modulated stereotactic radiosurgery treatment planning is needed to afford a highly accurate simulation of tiny IMRT fields. A virtual source model (VSM) of a mini multi-leaf collimator (MLC) (the Elekta Beam Modulator (EBM)) is presented, allowing efficient generation of particles even for small fields. The VSM of the EBM is based on a previously published virtual photon energy fluence model (VEF) (Fippel et al 2003 Med. Phys. 30 301) commissioned with large field measurements in air and in water. The original commissioning procedure of the VEF, based on large field measurements only, leads to inaccuracies for small fields. In order to improve the VSM, it was necessary to change the VEF model by developing (1) a method to determine the primary photon source diameter, relevant for output factor calculations, (2) a model of the influence of the flattening filter on the secondary photon spectrum and (3) a more realistic primary photon spectrum. The VSM model is used to generate the source phase space data above the mini-MLC. Later the particles are transmitted through the mini-MLC by a passive filter function which significantly speeds up the time of generation of the phase space data after the mini-MLC, used for calculation of the dose distribution in the patient. The improved VSM model was commissioned for 6 and 15 MV beams. The results of MC simulation are in very good agreement with measurements. Less than 2% of local difference between the MC simulation and the diamond detector measurement of the output factors in water was achieved. The X, Y and Z profiles measured in water with an ion chamber (V = 0.125 cm(3)) and a diamond detector were used to validate the models. An overall agreement of 2%/2 mm for high dose regions and 3%/2 mm in low dose regions between measurement and MC simulation for field sizes from 0.8 x 0.8 cm(2) to 16 x 21 cm(2) was achieved. An IMRT plan film verification

  10. SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Jin, L; Eldib, A; Li, J; Price, R; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

    2015-06-15

    Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reduce the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin.

  11. Quasi-Monte Carlo based global uncertainty and sensitivity analysis in modeling free product migration and recovery from petroleum-contaminated aquifers.

    Science.gov (United States)

    He, Li; Huang, Gordon; Lu, Hongwei; Wang, Shuo; Xu, Yi

    2012-06-15

    This paper presents a global uncertainty and sensitivity analysis (GUSA) framework based on global sensitivity analysis (GSA) and generalized likelihood uncertainty estimation (GLUE) methods. Quasi-Monte Carlo (QMC) is employed by GUSA to obtain realizations of uncertain parameters, which are then input to the simulation model for analysis. Compared to GLUE, GUSA can not only evaluate global sensitivity and uncertainty of modeling parameter sets, but also quantify the uncertainty in modeling prediction sets. Moreover, GUSA's another advantage lies in alleviation of computational effort, since those globally-insensitive parameters can be identified and removed from the uncertain-parameter set. GUSA is applied to a practical petroleum-contaminated site in Canada to investigate free product migration and recovery processes under aquifer remediation operations. Results from global sensitivity analysis show that (1) initial free product thickness has the most significant impact on total recovery volume but least impact on residual free product thickness and recovery rate; (2) total recovery volume and recovery rate are sensitive to residual LNAPL phase saturations and soil porosity. Results from uncertainty predictions reveal that the residual thickness would remain high and almost unchanged after about half-year of skimmer-well scheme; the rather high residual thickness (0.73-1.56 m 20 years later) indicates that natural attenuation would not be suitable for the remediation. The largest total recovery volume would be from water pumping, followed by vacuum pumping, and then skimmer. The recovery rates of the three schemes would rapidly decrease after 2 years (less than 0.05 m(3)/day), thus short-term remediation is not suggested. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Study on phase retardation characteristic of LCVR using dispersion analysis and SVM

    Institute of Scientific and Technical Information of China (English)

    HU; Dongmei; LIU; Quan; NIU; Guocheng; ZHU; Yifeng; YU; Lintao

    2015-01-01

    To calibrate the phase retardance of a Liquid crystal variable retarder(LCVR),its birefringence dispersion characteristic was analyzed,and the Support vector machines(SVM) algorithm was adopted to establish the prediction model.The obtained SVM decision function was used as a part of LCVR phase retardance,which was generated by the driving voltage.The experimental verification was carried out with a 568 nm laser.The results show that the deviation of the experimental value and the theoretical value is about 0.0061λ.SVM method could be used as an effective method for LCVR phase retardance characteristic calibration.

  13. SU-E-T-448: On the Perturbation Factor P-cav of the Markus Parallel Plate Ion Chambers in Clinical Electron Beams, Monte Carlo Based Reintegration of An Historical Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Voigts-Rhetz, P von; Zink, K [Technische Hochschule Mittelhessen - University of Applied Sciences, Giessen, Hessen (Germany)

    2014-06-01

    Purpose: All present dosimetry protocols recommend well-guarded parallel-plate ion chambers for electron dosimetry. For the guard-less Markus chamber an energy dependent fluence perturbation correction pcav is given. This perturbation correction was experimentally determined by van der Plaetsen by comparison of the read-out of a Markus and a NACP chamber, which was assumed to be “perturbation-free”. Aim of the present study is a Monte Carlo based reiteration of this experiment. Methods: Detailed models of four parallel-plate chambers (Roos, Markus, NACP and Advanced Markus) were designed using the Monte Carlo code EGSnrc and placed in a water phantom. For all chambers the dose to the active volume filled with low density water was calculated for 13 clinical electron spectra (E{sub 0}=6-21 MeV) at the depth of maximum and at the reference depth under reference conditions. In all cases the chamber's reference point was positioned at the depth of measurement. Moreover, the dose to water DW was calculated in a small water voxel positioned at the same depth. Results: The calculated dose ratio D{sub NACP}/D{sub Markus}, which according to van der Plaetsen reflects the fluence perturbation correction of the Markus chamber, deviates less from unity than the values given by van der Plaetsen's but exhibits a similar energy dependence. The same holds for the dose ratios of the other well guarded chambers. But, in comparison to water, the Markus chamber reveals the smallest overall perturbation correction which is nearly energy independent at both investigated depths. Conclusion: The simulations principally confirm the energy dependence of the dose ratio D{sub NACP}/D{sub Markus} as published by van der Plaetsen. But, as shown by our simulations of the ratio D{sub W}/D{sub Markus}, the conclusion drawn in all dosimetry protocols is questionable: in contrast to all well-guarded chambers the guard-less Markus chamber reveals the smallest overall perturbation

  14. In-line phase retarder and polarimeter for conversion of linear to circular polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Smith, N.V.; Denlinger, J.D. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    An in-line polarimeter including phase retarder and linear polarizer was designed and commissioned on undulator beamline 7.0 for the purpose of converting linear to circular polarization for experiments downstream. In commissioning studies, Mo/Si multilayers at 95 eV were used both as the upstream, freestanding phase retarder and the downstream linear polarized. The polarization properties of the phase retarder were characterized by direct polarimetry and by collecting MCD spectra in photoemission from Gd and other magnetic surfaces. The resonant birefringence of transmission multilayers results from differing distributions of s- and p-component wave fields in the multilayer when operating near a structural (Bragg) interference condition. The resulting phase retardation is especially strong when the interference is at or near the Brewster angle, which is roughly 45{degrees} in the EUV and soft x-ray ranges.

  15. Optimal Design of an Achromatic Angle-Insensitive Phase Retarder Used in MWIR Imaging Polarimetry

    Institute of Scientific and Technical Information of China (English)

    KiNG Guo-Guo; TAN Qiao-Feng; JIN Guo-Fan

    2009-01-01

    Dielectric gratings with period in the range from λ/10 to λ/4 with λ being the illumination wavelength not only exclude higher order diffractions but also exhibit strong dispersion of effective indices which are proportional to the wavelength. Moreover, they are insensitive to the incident angle of the illumination wave. With these features, we can design a true zero-order achromatic and angle-insensitive phase retarder which can be used as the polarization state analyzer in middle wave infrared (MWIR) imaging polarimetry. A design method using effective medium theory is described, and the performance of the designed phase retarder is evaluated by rigorous coupled wave analysis theory. The calculation results demonstrate that the retardance deviates from 45° by < ±1.6° within a field of view ±10° over the MWIR bandwidth (3-5μm).

  16. An Overview of Mode of Action and Analytical Methods for Evaluation of Gas Phase Activities of Flame Retardants

    Directory of Open Access Journals (Sweden)

    Khalifah A. Salmeia

    2015-03-01

    Full Text Available The latest techniques used to prove, describe and analyze the gas phase activity of a fire retardant used in polymeric materials are briefly reviewed. Classical techniques, such as thermogravimetric analysis or microscale combustion calorimetry, as well as complex and advanced analytical techniques, such as modified microscale combustion calorimeter (MCC, molecular beam mass spectroscopy and vacuum ultra violet (VUV photoionization spectroscopy coupled with time of flight MS (TOF-MS, are described in this review. The recent advances in analytical techniques help not only in determining the gas phase activity of the flame-retardants but also identify possible reactive species responsible for gas phase flame inhibition. The complete understanding of the decomposition pathways and the flame retardant activity of a flame retardant system is essential for the development of new eco-friendly-tailored flame retardant molecules with high flame retardant efficiency.

  17. Focal junctions retard lateral movement and disrupt fluid phase connectivity in the plasma membrane

    DEFF Research Database (Denmark)

    Vind-Kezunovic, D.; Wojewodzka, U.; Gniadecki, R.

    2008-01-01

    containing liquid-ordered (L-o) lipids. Indeed, values of maximal fluorescence recovery after photobleaching revealed that the long-range mobility of cholera toxin B subunit (CTB, marker of L-o) was similar to 1.5-fold retarded within the focal junctions compared to the surrounding membrane. However, 1......,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C-18:0), which specifically partitions to the liquid-disordered (L-d), non-raft phase, was also enriched in focal junctions and its mobility was slightly retarded. Cross-linking of GM(1) by CTB or raft aggregation by methyl...

  18. Simultaneous Absolute Measurements of Principal Angle and Phase Retardation with a New Common-Path Heterodyne Interferometer

    Science.gov (United States)

    Lo, Yu-Lung; Lai, Chun-Hau; Lin, Jing-Fung; Hsu, Ping-Feng

    2004-04-01

    This study demonstrates a new method for simultaneously measuring both the angle of the principal axis and the phase retardation of the linear birefringence in optical materials. We used a circular common-path interferometer (polariscope) as the basic structure modulated by an electro-optic (EO) modulator. An algorithm was developed to simultaneously measure the principal axis and the phase retardation of a lambda/4 or lambda/8 plate as a sample. In the case of a lambda/4 plate, the average absolute error of the principal axis is approximately 3.77°, and that of the phase retardation is approximately 1.03° (1.09%). The retardation error is within the 5% uncertainty range of a commercial wave plate. Fortunately, the nonlinear error caused by the reflection phase retardation of the beam splitter dose not appear in the new system. Therefore the error could be attributed to misalignment and defects in the EO modulator or the other optical components. As for the repeatability of this new common-path heterodyne interferometer, the average deviation for the principal axis is 0.186° and the phase retardation is 0.356°. For the stability, the average deviation for the principal axis is 0.405° and the phase retardation is 0.635°. The resolution of this new system is estimated to be ~0.5°, and the principal axis and phase retardation could be measured up to pi and 2pi, respectively, without ambiguity.

  19. [Phase transition behavior and thermodynamic analysis of hydrotalcite flame-retardant].

    Science.gov (United States)

    Zhang, Zhi-qing; Liao, Meng-chen; Zeng, Hong-yan; Xu, Sheng; Xu, Li-hua; Zhu, Pei-han; Yang, Yong-jie

    2015-01-01

    The hydrotalcite with the properties of flame-retardant, eliminating smoke, filling and thermostability is a new kind of inorganic flame retardant. In the work, the MgAl hydrotalcite as flame retardant with Mg/Al molar ratio of 4 (MgAl-LDH) was prepared by using urea as the precipitating agent. The thermolysis behavior of the MgAl-LDH flame retardant was investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and thermogravimetry-differential scanning calorimetry (TG-DSC) as well as self deconvolution and curve-fitting analyses. Thermal phase transition of the MgAl-LDH was clarified, especially the characteristics of the hydroxyl groups (-OH) in the brucite-like layers and the changes in coordinate of the carbonate (CO3(2-)) from the interlayers. Based on thermodynamic data, thermal decomposition process was discussed. By.XRD analysis; it was found that the phase change took place when the decomposition temperature increased. The MgAl-LDH was decarbonated basically to MgAl mixed metal oxides (Mg-Al-O) at 500 °C, and impurity MgAl204 phase formed at 600 °C. According to the analyses of FT-IR, TG-DSC and curve-fitting technique, the hydroxyl groups (-OH) in the brucite-like layers possessed three the ligands such as [Al-OH-Al], [Al-OH-Mg] and [Mg-OH-Mg] modes. Dehydroxylation of the brucite-like layers based on the binding forces, where the [Mg-OH-Mg] among the three modes was the most difficult to be re- moved during the pyrolysis process. In the same way, the CO3(2-) ligands also possessed three modes such as H2O-bridged CO3(2-), monodentate and bidentate coordination modes. Based on the thermodynamic analysis, the thermodynamic properties of the hydrotalcite as flame retardant were evaluated, and the expressions of the Gibbs free energy, (ΔrGθT), as a function of temperature, were derived for the Mg8Al2 (OH)20CO3 crystal. Thermodynamic analysis showed that the removal of -OH from the brucite-like layers was spontaneous process

  20. SU-E-T-561: Monte Carlo-Based Organ Dose Reconstruction Using Pre-Contoured Human Model for Hodgkins Lymphoma Patients Treated by Cobalt-60 External Beam Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J; Pelletier, C [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Pyakuryal, A; Lee, C [National Cancer Institute, Rockville, MD (United States)

    2015-06-15

    Purpose: Organ doses for the Hodgkin’s lymphoma patients treated with cobalt-60 radiation were estimated using an anthropomorphic model and Monte Carlo modeling. Methods: A cobalt-60 treatment unit modeled in the BEAMnrc Monte Carlo code was used to produce phase space data. The Monte Carlo simulation was verified with percent depth dose measurement in water at various field sizes. Radiation transport through the lung blocks were modeled by adjusting the weights of phase space data. We imported a precontoured adult female hybrid model and generated a treatment plan. The adjusted phase space data and the human model were imported to the XVMC Monte Carlo code for dose calculation. The organ mean doses were estimated and dose volume histograms were plotted. Results: The percent depth dose agreement between measurement and calculation in water phantom was within 2% for all field sizes. The mean organ doses of heart, left breast, right breast, and spleen for the selected case were 44.3, 24.1, 14.6 and 3.4 Gy, respectively with the midline prescription dose of 40.0 Gy. Conclusion: Organ doses were estimated for the patient group whose threedimensional images are not available. This development may open the door to more accurate dose reconstruction and estimates of uncertainties in secondary cancer risk for Hodgkin’s lymphoma patients. This work was partially supported by the intramural research program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.

  1. Flame Retardancy of Sorbitol Based Bioepoxy via Combined Solid and Gas Phase Action

    Directory of Open Access Journals (Sweden)

    Beáta Szolnoki

    2016-08-01

    Full Text Available Flame-retarded bioepoxy resins were prepared with the application of commercially available sorbitol polyglycidyl ether (SPE. The additive-type flame retardancy of the cycloaliphatic amine-cured SPE was investigated. Three-percent phosphorus (P-containing samples were prepared with the application of the liquid resorcinol bis(diphenyl phosphate (RDP, the solid ammonium polyphosphate (APP, and by combining them. Synergistic effect was found between the inorganic APP and the organophosphorus RDP, when applied in combination: formulations applying RDP or APP alone showed increased limiting oxygen index (LOI values, however, their UL-94 standard ratings remained HB. When the same amount of P originated from the two additives, V-0, self-extinguishing rating and LOI value of 34% (v/v was reached. By the combined approach the heat release rate of SPE could be lowered by approximately 60%. The assumed balanced solid and gas phase mechanism was confirmed by thermogravimetric analysis, Fourier transform infrared spectrometry (FTIR analysis (of the gases formed during laser pyrolysis, attenuated total reflection-infrared spectrometry (ATR-IR analysis (of the charred residues, as well as by mechanical testing (of the char obtained after combustion.

  2. Monte Carlo Based Toy Model for Fission Process

    CERN Document Server

    Kurniadi, R; Viridi, S

    2014-01-01

    Fission yield has been calculated notoriously by two calculations approach, macroscopic approach and microscopic approach. This work will proposes another calculation approach which the nucleus is treated as a toy model. The toy model of fission yield is a preliminary method that use random number as a backbone of the calculation. Because of nucleus as a toy model hence the fission process does not represent real fission process in nature completely. Fission event is modeled by one random number. The number is assumed as width of distribution probability of nucleon position in compound nuclei when fission process is started. The toy model is formed by Gaussian distribution of random number that randomizes distance like between particle and central point. The scission process is started by smashing compound nucleus central point into two parts that are left central and right central points. These three points have different Gaussian distribution parameters such as mean ({\\mu}CN, {\\mu}L, {\\mu}R), and standard d...

  3. Development and evaluation of Monte Carlo-based SPECT reconstruction

    NARCIS (Netherlands)

    Xiao, J.

    2009-01-01

    Single Photon Emission Computed Tomography (SPECT) is one of the most applied molecular imaging techniques to diagnose human diseases, e.g., of the heart, the brain or in oncology. For example, cardiac SPECT imaging plays a central role in diagnosing coronary heart diseases by providing clinicians w

  4. Monte Carlo based radial shield design of typical PWR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gul, Anas; Khan, Rustam; Qureshi, M. Ayub; Azeem, Muhammad Waqar; Raza, S.A. [Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan). Dept. of Nuclear Engineering; Stummer, Thomas [Technische Univ. Wien (Austria). Atominst.

    2016-11-15

    Neutron and gamma flux and dose equivalent rate distribution are analysed in radial and shields of a typical PWR type reactor based on the Monte Carlo radiation transport computer code MCNP5. The ENDF/B-VI continuous energy cross-section library has been employed for the criticality and shielding analysis. The computed results are in good agreement with the reference results (maximum difference is less than 56 %). It implies that MCNP5 a good tool for accurate prediction of neutron and gamma flux and dose rates in radial shield around the core of PWR type reactors.

  5. A Markov Chain Monte Carlo Based Method for System Identification

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, R E; Lee, C L; Nitao, J J; Hanley, W G

    2002-10-22

    This paper describes a novel methodology for the identification of mechanical systems and structures from vibration response measurements. It combines prior information, observational data and predictive finite element models to produce configurations and system parameter values that are most consistent with the available data and model. Bayesian inference and a Metropolis simulation algorithm form the basis for this approach. The resulting process enables the estimation of distributions of both individual parameters and system-wide states. Attractive features of this approach include its ability to: (1) provide quantitative measures of the uncertainty of a generated estimate; (2) function effectively when exposed to degraded conditions including: noisy data, incomplete data sets and model misspecification; (3) allow alternative estimates to be produced and compared, and (4) incrementally update initial estimates and analysis as more data becomes available. A series of test cases based on a simple fixed-free cantilever beam is presented. These results demonstrate that the algorithm is able to identify the system, based on the stiffness matrix, given applied force and resultant nodal displacements. Moreover, it effectively identifies locations on the beam where damage (represented by a change in elastic modulus) was specified.

  6. A Monte Carlo-based model of gold nanoparticle radiosensitization

    Science.gov (United States)

    Lechtman, Eli Solomon

    The goal of radiotherapy is to operate within the therapeutic window - delivering doses of ionizing radiation to achieve locoregional tumour control, while minimizing normal tissue toxicity. A greater therapeutic ratio can be achieved by utilizing radiosensitizing agents designed to enhance the effects of radiation at the tumour. Gold nanoparticles (AuNP) represent a novel radiosensitizer with unique and attractive properties. AuNPs enhance local photon interactions, thereby converting photons into localized damaging electrons. Experimental reports of AuNP radiosensitization reveal this enhancement effect to be highly sensitive to irradiation source energy, cell line, and AuNP size, concentration and intracellular localization. This thesis explored the physics and some of the underlying mechanisms behind AuNP radiosensitization. A Monte Carlo simulation approach was developed to investigate the enhanced photoelectric absorption within AuNPs, and to characterize the escaping energy and range of the photoelectric products. Simulations revealed a 10 3 fold increase in the rate of photoelectric absorption using low-energy brachytherapy sources compared to megavolt sources. For low-energy sources, AuNPs released electrons with ranges of only a few microns in the surrounding tissue. For higher energy sources, longer ranged photoelectric products travelled orders of magnitude farther. A novel radiobiological model called the AuNP radiosensitization predictive (ARP) model was developed based on the unique nanoscale energy deposition pattern around AuNPs. The ARP model incorporated detailed Monte Carlo simulations with experimentally determined parameters to predict AuNP radiosensitization. This model compared well to in vitro experiments involving two cancer cell lines (PC-3 and SK-BR-3), two AuNP sizes (5 and 30 nm) and two source energies (100 and 300 kVp). The ARP model was then used to explore the effects of AuNP intracellular localization using 1.9 and 100 nm AuNPs, and 100 and 300 kVp source energies. The impact of AuNP localization was most significant for low-energy sources. At equal mass concentrations, AuNP size did not impact radiosensitization unless the AuNPs were localized in the nucleus. This novel predictive model of AuNP radiosensitization could help define the optimal use of AuNPs in potential clinical strategies by determining therapeutic AuNP concentrations, and recommending when active approaches to cellular accumulation are most beneficial.

  7. A Monte Carlo Based Analysis of Optimal Design Criteria

    Science.gov (United States)

    2011-11-09

    MATLAB’s fmincon or SolvOpt, developed by A. Kuntsevich and F. Kappel [18, 17], with four variations of the constraint implementation. We denote by (C1...Statistics, John Wiley & Sons, Inc., New York, NY, 1981. [17] F. Kappel and A. V. Kuntsevich , An implementation of Shor’s r-algorithm, Computational...Optimization and Applications, 15 (2000), 193–205. [18] A. Kuntsevich and F. Kappel, SolvOpt, retrieved December 2009, from http://www.kfunigraz.ac.at

  8. A Monte Carlo based spent fuel analysis safeguards strategy assessment

    Energy Technology Data Exchange (ETDEWEB)

    Fensin, Michael L [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Menlove, Howard O [Los Alamos National Laboratory; Sandoval, Nathan P [Los Alamos National Laboratory

    2009-01-01

    Safeguarding nuclear material involves the detection of diversions of significant quantities of nuclear materials, and the deterrence of such diversions by the risk of early detection. There are a variety of motivations for quantifying plutonium in spent fuel assemblies by means of nondestructive assay (NDA) including the following: strengthening the capabilities of the International Atomic Energy Agencies ability to safeguards nuclear facilities, shipper/receiver difference, input accountability at reprocessing facilities and burnup credit at repositories. Many NDA techniques exist for measuring signatures from spent fuel; however, no single NDA technique can, in isolation, quantify elemental plutonium and other actinides of interest in spent fuel. A study has been undertaken to determine the best integrated combination of cost effective techniques for quantifying plutonium mass in spent fuel for nuclear safeguards. A standardized assessment process was developed to compare the effective merits and faults of 12 different detection techniques in order to integrate a few techniques and to down-select among the techniques in preparation for experiments. The process involves generating a basis burnup/enrichment/cooling time dependent spent fuel assembly library, creating diversion scenarios, developing detector models and quantifying the capability of each NDA technique. Because hundreds of input and output files must be managed in the couplings of data transitions for the different facets of the assessment process, a graphical user interface (GUI) was development that automates the process. This GUI allows users to visually create diversion scenarios with varied replacement materials, and generate a MCNPX fixed source detector assessment input file. The end result of the assembly library assessment is to select a set of common source terms and diversion scenarios for quantifying the capability of each of the 12 NDA techniques. We present here the generalized assessment process, the techniques employed to automate the coupled facets of the assessment process, and the standard burnup/enrichment/cooling time dependent spent fuel assembly library. We also clearly define the diversion scenarios that will be analyzed during the standardized assessments. Though this study is currently limited to generic PWR assemblies, it is expected that the results of the assessment will yield an adequate spent fuel analysis strategy knowledge that will help the down-select process for other reactor types.

  9. Hardware acceleration of Monte Carlo-based simulations

    OpenAIRE

    Echeverría Aramendi, Pedro

    2011-01-01

    During the last years there has been an enormous advance in FPGAs. Traditionally, FPGAs have been used mainly for prototyping as they offer significant advantages at a suitable low cost: flexibility and verification easiness. Their flexibility allows the implementation of different generations of a given application and provides space to designers to modify implementations until the very last moment, or even correct mistakes once the product has been released. Second, the verification of a de...

  10. Green's function of a massless scalar field in curved space-time and superluminal phase velocity of the retarded potential

    CERN Document Server

    Dai, De-Chang

    2012-01-01

    We study a retarded potential solution of a massless scalar field in curved space-time. In a special ansatz for a particle at rest whose magnitude of the (scalar) charge is changing with time, we found an exact analytic solution. The solution indicates that the phase velocity of the retarded potential of a non-moving scalar charge is position dependent, and may easily be greater than the speed of light at a given point. In the case of the Schwarzschild space-time, at the horizon, the phase velocity becomes infinitely faster than the coordinate speed of light at that point. Superluminal phase velocity is relatively common phenomenon, with the the phase velocity of the massive Klein-Gordon field as the best known example. We discuss why it is possible to have modes with superluminal phase velocity even for a massless field.

  11. Fabric phase sorptive extraction: Two practical sample pretreatment techniques for brominated flame retardants in water.

    Science.gov (United States)

    Huang, Guiqi; Dong, Sheying; Zhang, Mengfei; Zhang, Haihan; Huang, Tinglin

    2016-09-15

    Sample pretreatment is the critical section for residue monitoring of hazardous pollutants. In this paper, using the cellulose fabric as host matrix, three extraction sorbents such as poly (tetrahydrofuran) (PTHF), poly (ethylene glycol) (PEG) and poly (dimethyldiphenylsiloxane) (PDMDPS), were prepared on the surface of the cellulose fabric. Two practical extraction techniques including stir bar fabric phase sorptive extraction (stir bar-FPSE) and magnetic stir fabric phase sorptive extraction (magnetic stir-FPSE) have been designed, which allow stirring of fabric phase sorbent during the whole extraction process. In the meantime, three brominated flame retardants (BFRs) [tetrabromobisphenol A (TBBPA), tetrabromobisphenol A bisallylether (TBBPA-BAE), tetrabromobisphenol A bis(2,3-dibromopropyl)ether (TBBPA-BDBPE)] in the water sample were selected as model analytes for the practical evaluation of the proposed two techniques using high-performance liquid chromatography (HPLC). Moreover, various experimental conditions affecting extraction process such as the type of fabric phase, extraction time, the amount of salt and elution conditions were also investigated. Due to the large sorbent loading capacity and unique stirring performance, both techniques possessed high extraction capability and fast extraction equilibrium. Under the optimized conditions, high recoveries (90-99%) and low limits of detection (LODs) (0.01-0.05 μg L(-1)) were achieved. In addition, the reproducibility was obtained by evaluating the intraday and interday precisions with relative standard deviations (RSDs) less than 5.1% and 6.8%, respectively. The results indicated that two pretreatment techniques were promising and practical for monitoring of hazardous pollutants in the water sample. Due to low solvent consumption and high repeated use performance, proposed techniques also could meet green analytical criteria.

  12. Miniature Compressive Ultra-spectral Imaging System Utilizing a Single Liquid Crystal Phase Retarder

    Science.gov (United States)

    August, Isaac; Oiknine, Yaniv; Abuleil, Marwan; Abdulhalim, Ibrahim; Stern, Adrian

    2016-03-01

    Spectroscopic imaging has been proved to be an effective tool for many applications in a variety of fields, such as biology, medicine, agriculture, remote sensing and industrial process inspection. However, due to the demand for high spectral and spatial resolution it became extremely challenging to design and implement such systems in a miniaturized and cost effective manner. Using a Compressive Sensing (CS) setup based on a single variable Liquid Crystal (LC) retarder and a sensor array, we present an innovative Miniature Ultra-Spectral Imaging (MUSI) system. The LC retarder acts as a compact wide band spectral modulator. Within the framework of CS, a sequence of spectrally modulated images is used to recover ultra-spectral image cubes. Using the presented compressive MUSI system, we demonstrate the reconstruction of gigapixel spatio-spectral image cubes from spectral scanning shots numbering an order of magnitude less than would be required using conventional systems.

  13. Quantitative structure-retardation factor relationship of protein amino acids in different solvent mixtures for normal-phase thin-layer chromatography.

    Science.gov (United States)

    Yousefinejad, Saeed; Honarasa, Fatemeh; Saeed, Negar

    2015-05-01

    A quantitative predictive/descriptive model was proposed for the retardation factors of protein amino acids in normal-phase thin-layer chromatography. The experimental retardation factors of 126 chromatographic mixtures (21 protein amino acids in different mobile phases) were used as the independent variable. The matrix of dependent variables of the model was built using structural descriptors of amino acids and empirical parameters of solvents of the applied mobile phases. After variable selection, a five-parametr model was proposed for the retardation factor of amino acids, which covered about 84 and 77% variance of data in training and cross-validation, respectively. The correlation coefficient of the external test set was 0.80, which shows the prediction potential of proposed model as well as its good applicability domain that was checked using a standardized residual-leverage plot. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Viewing angle switching of liquid crystal display using fringe-field switching to control off-axis phase retardation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Young Jin; Kim, Jin Ho; Her, Jung Hwa; Lee, Seung Hee [Polymer BIN Fusion Research Center, Department of Polymer Nano-Science and Technology, Chonbuk National University, Chonju, Chonbuk 561-756 (Korea, Republic of); Park, Kyoung Ho; Lee, Joun Ho; Kim, Byeong Koo [Mobile Product Development Department, LG Display Company, Ltd, Gumi, Gyungbuk 730-350 (Korea, Republic of); Kang, Wan-Seok; Lee, Gi-Dong, E-mail: gdlee@dau.ac.k, E-mail: lsh1@chonbuk.ac.k [Department of Electronics Engineering, Dong-A University, Pusan 604-714 (Korea, Republic of)

    2010-03-03

    A viewing angle switchable liquid crystal display associated with fringe-field switching mode is proposed. In the device, one pixel is composed of a main pixel and a sub-pixel, in which both pixels are formed to generate a fringe electric field. However, the field directions are different from each other so that in the main pixel, the fringe field rotates the liquid crystal for displaying the main image, whereas it controls only the tilt angle of the liquid crystal without rotating in the sub-pixel region. In this way, phase retardation to cause leakage of light at the off-normal axis can be generated in the sub-pixel, and by utilizing the light, the main displayed image in the normal direction can be blocked in the oblique viewing direction.

  15. Modeling contaminant transport in a three-phase groundwater system with the Freundlich-type retardation factor.

    Science.gov (United States)

    Kim, M; Kim, S B

    2007-02-01

    Colloid-facilitated contaminant transport was simulated in this study for the three-phase groundwater system where one or more sorption processes can be described with nonlinear sorption isotherm (Freundlich isotherm). A concise form of contaminant transport equation was derived from the mass balance equation of the contaminant. The developed model was numerically solved by the finite difference method along with the Picard iteration. The simulation results were used to quantitatively analyze the previously reported column data showing nonlinear sorption behavior. The analysis led to the following observations: (i) increases of the distribution coefficient of contaminant between the aqueous and solid phases (K(S)c) and the one between the dissolved natural organic matters and solid phase ( K(S)OM) generate less facilitation (i.e., late arrival of contaminant breakthrough curves (BTCs), and the distribution coefficient of contaminant between the aqueous and the solid phases (K(OM)c) gives the opposite result; (ii) the increase of the Freundlich constant for the sorption isotherm between the aqueous and the solid phases (N(S)c) yields the late arrival of BTC, and the other two Freundlich constants produce the opposite results; (iii) the Freundlich constants generally yield a sharper front as the BTC arrives at later pore volumes, while the distribution coefficients generally yield a more spread of the BTC as it arrives at later volumes. This modeling study shows that transport modeling provides a more efficient analyzing tool than the retardation factor alone concerning the colloid-facilitated contaminant transport with nonlinear sorption processes.

  16. Epstein-Barr virus BGLF4 kinase retards cellular S-phase progression and induces chromosomal abnormality.

    Directory of Open Access Journals (Sweden)

    Yu-Hsin Chang

    Full Text Available Epstein-Barr virus (EBV induces an uncoordinated S-phase-like cellular environment coupled with multiple prophase-like events in cells replicating the virus. The EBV encoded Ser/Thr kinase BGLF4 has been shown to induce premature chromosome condensation through activation of condensin and topoisomerase II and reorganization of the nuclear lamina to facilitate the nuclear egress of nucleocapsids in a pathway mimicking Cdk1. However, the observation that RB is hyperphosphorylated in the presence of BGLF4 raised the possibility that BGLF4 may have a Cdk2-like activity to promote S-phase progression. Here, we investigated the regulatory effects of BGLF4 on cell cycle progression and found that S-phase progression and DNA synthesis were interrupted by BGLF4 in mammalian cells. Expression of BGLF4 did not compensate Cdk1 defects for DNA replication in S. cerevisiae. Using time-lapse microscopy, we found the fate of individual HeLa cells was determined by the expression level of BGLF4. In addition to slight cell growth retardation, BGLF4 elicits abnormal chromosomal structure and micronucleus formation in 293 and NCP-TW01 cells. In Saos-2 cells, BGLF4 induced the hyperphosphorylation of co-transfected RB, while E2F1 was not released from RB-E2F1 complexes. The E2F1 regulated activities of the cyclin D1 and ZBRK1 promoters were suppressed by BGLF4 in a dose dependent manner. Detection with phosphoamino acid specific antibodies revealed that, in addition to Ser780, phosphorylation of the DNA damage-responsive Ser612 on RB was enhanced by BGLF4. Taken together, our study indicates that BGLF4 may directly or indirectly induce a DNA damage signal that eventually interferes with host DNA synthesis and delays S-phase progression.

  17. Analysis of Flame Retardancy in Polymer Blends by Synchrotron X-ray K-edge Tomography and Interferometric Phase Contrast Movies.

    Science.gov (United States)

    Olatinwo, Mutairu B; Ham, Kyungmin; McCarney, Jonathan; Marathe, Shashidhara; Ge, Jinghua; Knapp, Gerry; Butler, Leslie G

    2016-03-10

    Underwriters Laboratories 94 test bars have been imaged with X-ray K-edge tomography between 12 and 32 keV to assess the bromine and antimony concentration gradient across char layers of partially burnt samples. Phase contrast tomography on partially burnt samples showed gas bubbles and dark-field scattering ascribed to residual blend inhomogeneity. In addition, single-shot grating interferometry was used to record X-ray movies of test samples during heating (IR and flame) intended to mimic the UL 94 plastics flammability test. The UL 94 test bars were formulated with varying concentrations of a brominated flame retardant, Saytex 8010, and a synergist, Sb2O3, blended into high-impact polystyrene (HIPS). Depending on the sample composition, samples will pass or fail the UL 94 plastics flammability test. Tomography and interferometry imaging show differences that correlate with UL 94 performance. Key features such as char layer, gas bubble formation, microcracks, and dissolution of the flame retardant in the char layer regions are used in understanding the efficiency of the flame retardant and synergist. The samples that pass the UL 94 test have a thick, highly visible char layer as well as an interior rich in gas bubbles. Growth of gas bubbles from flame-retardant thermal decomposition is noted in the X-ray phase contrast movies. Also noteworthy is an absence of bubbles near the burning surface of the polymer; dark-field images after burning suggest a microcrack structure between interior bubbles and the surface. The accepted mechanism for flame retardant activity includes free radical quenching in the flame by bromine and antimony species. The imaging supports this as well as provides a fast inspection of other parameters, such as viscosity and surface tension.

  18. Monte Carlo based geometrical model for efficiency calculation of an n-type HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Padilla Cabal, Fatima, E-mail: fpadilla@instec.c [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba); Lopez-Pino, Neivy; Luis Bernal-Castillo, Jose; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D' Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba)

    2010-12-15

    A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ({sup 241}Am, {sup 133}Ba, {sup 22}Na, {sup 60}Co, {sup 57}Co, {sup 137}Cs and {sup 152}Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized.

  19. Monte Carlo-based treatment planning system calculation engine for microbeam radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Rovira, I.; Sempau, J.; Prezado, Y. [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, Barcelona E-08028 (Spain) and ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz B.P. 220, F-38043 Grenoble Cedex (France); Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, Barcelona E-08028 (Spain); Laboratoire Imagerie et modelisation en neurobiologie et cancerologie, UMR8165, Centre National de la Recherche Scientifique (CNRS), Universites Paris 7 et Paris 11, Bat 440., 15 rue Georges Clemenceau, F-91406 Orsay Cedex (France)

    2012-05-15

    Purpose: Microbeam radiation therapy (MRT) is a synchrotron radiotherapy technique that explores the limits of the dose-volume effect. Preclinical studies have shown that MRT irradiations (arrays of 25-75-{mu}m-wide microbeams spaced by 200-400 {mu}m) are able to eradicate highly aggressive animal tumor models while healthy tissue is preserved. These promising results have provided the basis for the forthcoming clinical trials at the ID17 Biomedical Beamline of the European Synchrotron Radiation Facility (ESRF). The first step includes irradiation of pets (cats and dogs) as a milestone before treatment of human patients. Within this context, accurate dose calculations are required. The distinct features of both beam generation and irradiation geometry in MRT with respect to conventional techniques require the development of a specific MRT treatment planning system (TPS). In particular, a Monte Carlo (MC)-based calculation engine for the MRT TPS has been developed in this work. Experimental verification in heterogeneous phantoms and optimization of the computation time have also been performed. Methods: The penelope/penEasy MC code was used to compute dose distributions from a realistic beam source model. Experimental verification was carried out by means of radiochromic films placed within heterogeneous slab-phantoms. Once validation was completed, dose computations in a virtual model of a patient, reconstructed from computed tomography (CT) images, were performed. To this end, decoupling of the CT image voxel grid (a few cubic millimeter volume) to the dose bin grid, which has micrometer dimensions in the transversal direction of the microbeams, was performed. Optimization of the simulation parameters, the use of variance-reduction (VR) techniques, and other methods, such as the parallelization of the simulations, were applied in order to speed up the dose computation. Results: Good agreement between MC simulations and experimental results was achieved, even at the interfaces between two different media. Optimization of the simulation parameters and the use of VR techniques saved a significant amount of computation time. Finally, parallelization of the simulations improved even further the calculation time, which reached 1 day for a typical irradiation case envisaged in the forthcoming clinical trials in MRT. An example of MRT treatment in a dog's head is presented, showing the performance of the calculation engine. Conclusions: The development of the first MC-based calculation engine for the future TPS devoted to MRT has been accomplished. This will constitute an essential tool for the future clinical trials on pets at the ESRF. The MC engine is able to calculate dose distributions in micrometer-sized bins in complex voxelized CT structures in a reasonable amount of time. Minimization of the computation time by using several approaches has led to timings that are adequate for pet radiotherapy at synchrotron facilities. The next step will consist in its integration into a user-friendly graphical front-end.

  20. Monte Carlo based unit commitment procedures for the deregulated market environment

    Energy Technology Data Exchange (ETDEWEB)

    Granelli, G.P.; Marannino, P.; Montagna, M.; Zanellini, F. [Universita di Pavia, Pavia (Italy). Dipartimento di Ingegneria Elettrica

    2006-12-15

    The unit commitment problem, originally conceived in the framework of short term operation of vertically integrated utilities, needs a thorough re-examination in the light of the ongoing transition towards the open electricity market environment. In this work the problem is re-formulated to adapt unit commitment to the viewpoint of a generation company (GENCO) which is no longer bound to satisfy its load, but is willing to maximize its profits. Moreover, with reference to the present day situation in many countries, the presence of a GENCO (the former monopolist) which is in the position of exerting the market power, requires a careful analysis to be carried out considering the different perspectives of a price taker and of the price maker GENCO. Unit commitment is thus shown to lead to a couple of distinct, yet slightly different problems. The unavoidable uncertainties in load profile and price behaviour over the time period of interest are also taken into account by means of a Monte Carlo simulation. Both the forecasted loads and prices are handled as random variables with a normal multivariate distribution. The correlation between the random input variables corresponding to successive hours of the day was considered by carrying out a statistical analysis of actual load and price data. The whole procedure was tested making use of reasonable approximations of the actual data of the thermal generation units available to come actual GENCOs operating in Italy. (author)

  1. Monte Carlo based calibration of scintillation detectors for laboratory and in situ gamma ray measurements

    NARCIS (Netherlands)

    van der Graaf, E. R.; Limburg, J.; Koomans, R. L.; Tijs, M.

    2011-01-01

    The calibration of scintillation detectors for gamma radiation in a well characterized setup can be transferred to other geometries using Monte Carlo simulations to account for the differences between the calibration and the other geometry. In this study a calibration facility was used that is const

  2. Monte Carlo-based revised values of dose rate constants at discrete photon energies

    Directory of Open Access Journals (Sweden)

    T Palani Selvam

    2014-01-01

    Full Text Available Absorbed dose rate to water at 0.2 cm and 1 cm due to a point isotropic photon source as a function of photon energy is calculated using the EDKnrc user-code of the EGSnrc Monte Carlo system. This code system utilized widely used XCOM photon cross-section dataset for the calculation of absorbed dose to water. Using the above dose rates, dose rate constants are calculated. Air-kerma strength S k needed for deriving dose rate constant is based on the mass-energy absorption coefficient compilations of Hubbell and Seltzer published in the year 1995. A comparison of absorbed dose rates in water at the above distances to the published values reflects the differences in photon cross-section dataset in the low-energy region (difference is up to 2% in dose rate values at 1 cm in the energy range 30-50 keV and up to 4% at 0.2 cm at 30 keV. A maximum difference of about 8% is observed in the dose rate value at 0.2 cm at 1.75 MeV when compared to the published value. S k calculations based on the compilation of Hubbell and Seltzer show a difference of up to 2.5% in the low-energy region (20-50 keV when compared to the published values. The deviations observed in the values of dose rate and S k affect the values of dose rate constants up to 3%.

  3. An automated Monte-Carlo based method for the calculation of cascade summing factors

    Science.gov (United States)

    Jackson, M. J.; Britton, R.; Davies, A. V.; McLarty, J. L.; Goodwin, M.

    2016-10-01

    A versatile method has been developed to calculate cascade summing factors for use in quantitative gamma-spectrometry analysis procedures. The proposed method is based solely on Evaluated Nuclear Structure Data File (ENSDF) nuclear data, an X-ray energy library, and accurate efficiency characterisations for single detector counting geometries. The algorithm, which accounts for γ-γ, γ-X, γ-511 and γ-e- coincidences, can be applied to any design of gamma spectrometer and can be expanded to incorporate any number of nuclides. Efficiency characterisations can be derived from measured or mathematically modelled functions, and can accommodate both point and volumetric source types. The calculated results are shown to be consistent with an industry standard gamma-spectrometry software package. Additional benefits including calculation of cascade summing factors for all gamma and X-ray emissions, not just the major emission lines, are also highlighted.

  4. An exercise in model validation: Comparing univariate statistics and Monte Carlo-based multivariate statistics

    Energy Technology Data Exchange (ETDEWEB)

    Weathers, J.B. [Shock, Noise, and Vibration Group, Northrop Grumman Shipbuilding, P.O. Box 149, Pascagoula, MS 39568 (United States)], E-mail: James.Weathers@ngc.com; Luck, R. [Department of Mechanical Engineering, Mississippi State University, 210 Carpenter Engineering Building, P.O. Box ME, Mississippi State, MS 39762-5925 (United States)], E-mail: Luck@me.msstate.edu; Weathers, J.W. [Structural Analysis Group, Northrop Grumman Shipbuilding, P.O. Box 149, Pascagoula, MS 39568 (United States)], E-mail: Jeffrey.Weathers@ngc.com

    2009-11-15

    The complexity of mathematical models used by practicing engineers is increasing due to the growing availability of sophisticated mathematical modeling tools and ever-improving computational power. For this reason, the need to define a well-structured process for validating these models against experimental results has become a pressing issue in the engineering community. This validation process is partially characterized by the uncertainties associated with the modeling effort as well as the experimental results. The net impact of the uncertainties on the validation effort is assessed through the 'noise level of the validation procedure', which can be defined as an estimate of the 95% confidence uncertainty bounds for the comparison error between actual experimental results and model-based predictions of the same quantities of interest. Although general descriptions associated with the construction of the noise level using multivariate statistics exists in the literature, a detailed procedure outlining how to account for the systematic and random uncertainties is not available. In this paper, the methodology used to derive the covariance matrix associated with the multivariate normal pdf based on random and systematic uncertainties is examined, and a procedure used to estimate this covariance matrix using Monte Carlo analysis is presented. The covariance matrices are then used to construct approximate 95% confidence constant probability contours associated with comparison error results for a practical example. In addition, the example is used to show the drawbacks of using a first-order sensitivity analysis when nonlinear local sensitivity coefficients exist. Finally, the example is used to show the connection between the noise level of the validation exercise calculated using multivariate and univariate statistics.

  5. A Monte Carlo-based treatment-planning tool for ion beam therapy

    CERN Document Server

    Böhlen, T T; Dosanjh, M; Ferrari, A; Haberer, T; Parodi, K; Patera, V; Mairan, A

    2013-01-01

    Ion beam therapy, as an emerging radiation therapy modality, requires continuous efforts to develop and improve tools for patient treatment planning (TP) and research applications. Dose and fluence computation algorithms using the Monte Carlo (MC) technique have served for decades as reference tools for accurate dose computations for radiotherapy. In this work, a novel MC-based treatment-planning (MCTP) tool for ion beam therapy using the pencil beam scanning technique is presented. It allows single-field and simultaneous multiple-fields optimization for realistic patient treatment conditions and for dosimetric quality assurance for irradiation conditions at state-of-the-art ion beam therapy facilities. It employs iterative procedures that allow for the optimization of absorbed dose and relative biological effectiveness (RBE)-weighted dose using radiobiological input tables generated by external RBE models. Using a re-implementation of the local effect model (LEM), theMCTP tool is able to perform TP studies u...

  6. Monte Carlo-based diode design for correction-less small field dosimetry

    Science.gov (United States)

    Charles, P. H.; Crowe, S. B.; Kairn, T.; Knight, R. T.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

    2013-07-01

    Due to their small collecting volume, diodes are commonly used in small field dosimetry. However, the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore, this study uses Monte Carlo simulations to look at introducing air upstream to diodes such that they measure with a constant sensitivity across all field sizes in small field dosimetry. Varying thicknesses of air were introduced onto the upstream end of two commercial diodes (PTW 60016 photon diode and PTW 60017 electron diode), as well as a theoretical unenclosed silicon chip using field sizes as small as 5 mm × 5 mm. The metric \\frac{{D_{w,Q} }}{{D_{Det,Q} }} used in this study represents the ratio of the dose to a point of water to the dose to the diode active volume, for a particular field size and location. The optimal thickness of air required to provide a constant sensitivity across all small field sizes was found by plotting \\frac{{D_{w,Q} }}{{D_{Det,Q} }} as a function of introduced air gap size for various field sizes, and finding the intersection point of these plots. That is, the point at which \\frac{{D_{w,Q} }}{{D_{Det,Q} }} was constant for all field sizes was found. The optimal thickness of air was calculated to be 3.3, 1.15 and 0.10 mm for the photon diode, electron diode and unenclosed silicon chip, respectively. The variation in these results was due to the different design of each detector. When calculated with the new diode design incorporating the upstream air gap, k_{Q_{clin} ,Q_{msr} }^{f_{clin} ,f_{msr} } was equal to unity to within statistical uncertainty (0.5%) for all three diodes. Cross-axis profile measurements were also improved with the new detector design. The upstream air gap could be implanted on the commercial diodes via a cap consisting of the air cavity surrounded by water equivalent material. The results for the unclosed silicon chip show that an ideal small field dosimetry diode could be created by using a silicon chip with a small amount of air above it.

  7. Monte Carlo-based adaptive EPID dose kernel accounting for different field size responses of imagers.

    Science.gov (United States)

    Wang, Song; Gardner, Joseph K; Gordon, John J; Li, Weidong; Clews, Luke; Greer, Peter B; Siebers, Jeffrey V

    2009-08-01

    The aim of this study is to present an efficient method to generate imager-specific Monte Carlo (MC)-based dose kernels for amorphous silicon-based electronic portal image device dose prediction and determine the effective backscattering thicknesses for such imagers. EPID field size-dependent responses were measured for five matched Varian accelerators from three institutions with 6 MV beams at the source to detector distance (SDD) of 105 cm. For two imagers, measurements were made with and without the imager mounted on the robotic supporting arm. Monoenergetic energy deposition kernels with 0-2.5 cm of water backscattering thicknesses were simultaneously computed by MC to a high precision. For each imager, the backscattering thickness required to match measured field size responses was determined. The monoenergetic kernel method was validated by comparing measured and predicted field size responses at 150 cm SDD, 10 x 10 cm2 multileaf collimator (MLC) sliding window fields created with 5, 10, 20, and 50 mm gaps, and a head-and-neck (H&N) intensity modulated radiation therapy (IMRT) patient field. Field size responses for the five different imagers deviated by up to 1.3%. When imagers were removed from the robotic arms, response deviations were reduced to 0.2%. All imager field size responses were captured by using between 1.0 and 1.6 cm backscatter. The predicted field size responses by the imager-specific kernels matched measurements for all involved imagers with the maximal deviation of 0.34%. The maximal deviation between the predicted and measured field size responses at 150 cm SDD is 0.39%. The maximal deviation between the predicted and measured MLC sliding window fields is 0.39%. For the patient field, gamma analysis yielded that 99.0% of the pixels have gamma < 1 by the 2%, 2 mm criteria with a 3% dose threshold. Tunable imager-specific kernels can be generated rapidly and accurately in a single MC simulation. The resultant kernels are imager position independent and are able to predict fields with varied incident energy spectra and a H&N IMRT patient field. The proposed adaptive EPID dose kernel method provides the necessary infrastructure to build reliable and accurate portal dosimetry systems.

  8. Experimental validation of a rapid Monte Carlo based micro-CT simulator

    Science.gov (United States)

    Colijn, A. P.; Zbijewski, W.; Sasov, A.; Beekman, F. J.

    2004-09-01

    We describe a newly developed, accelerated Monte Carlo simulator of a small animal micro-CT scanner. Transmission measurements using aluminium slabs are employed to estimate the spectrum of the x-ray source. The simulator incorporating this spectrum is validated with micro-CT scans of physical water phantoms of various diameters, some containing stainless steel and Teflon rods. Good agreement is found between simulated and real data: normalized error of simulated projections, as compared to the real ones, is typically smaller than 0.05. Also the reconstructions obtained from simulated and real data are found to be similar. Thereafter, effects of scatter are studied using a voxelized software phantom representing a rat body. It is shown that the scatter fraction can reach tens of per cents in specific areas of the body and therefore scatter can significantly affect quantitative accuracy in small animal CT imaging.

  9. Monte-Carlo based Uncertainty Analysis For CO2 Laser Microchanneling Model

    Science.gov (United States)

    Prakash, Shashi; Kumar, Nitish; Kumar, Subrata

    2016-09-01

    CO2 laser microchanneling has emerged as a potential technique for the fabrication of microfluidic devices on PMMA (Poly-methyl-meth-acrylate). PMMA directly vaporizes when subjected to high intensity focused CO2 laser beam. This process results in clean cut and acceptable surface finish on microchannel walls. Overall, CO2 laser microchanneling process is cost effective and easy to implement. While fabricating microchannels on PMMA using a CO2 laser, the maximum depth of the fabricated microchannel is the key feature. There are few analytical models available to predict the maximum depth of the microchannels and cut channel profile on PMMA substrate using a CO2 laser. These models depend upon the values of thermophysical properties of PMMA and laser beam parameters. There are a number of variants of transparent PMMA available in the market with different values of thermophysical properties. Therefore, for applying such analytical models, the values of these thermophysical properties are required to be known exactly. Although, the values of laser beam parameters are readily available, extensive experiments are required to be conducted to determine the value of thermophysical properties of PMMA. The unavailability of exact values of these property parameters restrict the proper control over the microchannel dimension for given power and scanning speed of the laser beam. In order to have dimensional control over the maximum depth of fabricated microchannels, it is necessary to have an idea of uncertainty associated with the predicted microchannel depth. In this research work, the uncertainty associated with the maximum depth dimension has been determined using Monte Carlo method (MCM). The propagation of uncertainty with different power and scanning speed has been predicted. The relative impact of each thermophysical property has been determined using sensitivity analysis.

  10. Monte Carlo based protocol for cell survival and tumour control probability in BNCT

    Science.gov (United States)

    Ye, Sung-Joon

    1999-02-01

    A mathematical model to calculate the theoretical cell survival probability (nominally, the cell survival fraction) is developed to evaluate preclinical treatment conditions for boron neutron capture therapy (BNCT). A treatment condition is characterized by the neutron beam spectra, single or bilateral exposure, and the choice of boron carrier drug (boronophenylalanine (BPA) or boron sulfhydryl hydride (BSH)). The cell survival probability defined from Poisson statistics is expressed with the cell-killing yield, the (n, ) reaction density, and the tolerable neutron fluence. The radiation transport calculation from the neutron source to tumours is carried out using Monte Carlo methods: (i) reactor-based BNCT facility modelling to yield the neutron beam library at an irradiation port; (ii) dosimetry to limit the neutron fluence below a tolerance dose (10.5 Gy-Eq); (iii) calculation of the (n, ) reaction density in tumours. A shallow surface tumour could be effectively treated by single exposure producing an average cell survival probability of - for probable ranges of the cell-killing yield for the two drugs, while a deep tumour will require bilateral exposure to achieve comparable cell kills at depth. With very pure epithermal beams eliminating thermal, low epithermal and fast neutrons, the cell survival can be decreased by factors of 2-10 compared with the unmodified neutron spectrum. A dominant effect of cell-killing yield on tumour cell survival demonstrates the importance of choice of boron carrier drug. However, these calculations do not indicate an unambiguous preference for one drug, due to the large overlap of tumour cell survival in the probable ranges of the cell-killing yield for the two drugs. The cell survival value averaged over a bulky tumour volume is used to predict the overall BNCT therapeutic efficacy, using a simple model of tumour control probability (TCP).

  11. Monte Carlo based water/medium stopping-power ratios for various ICRP and ICRU tissues.

    Science.gov (United States)

    Fernández-Varea, José M; Carrasco, Pablo; Panettieri, Vanessa; Brualla, Lorenzo

    2007-11-07

    Water/medium stopping-power ratios, s(w,m), have been calculated for several ICRP and ICRU tissues, namely adipose tissue, brain, cortical bone, liver, lung (deflated and inflated) and spongiosa. The considered clinical beams were 6 and 18 MV x-rays and the field size was 10 x 10 cm(2). Fluence distributions were scored at a depth of 10 cm using the Monte Carlo code PENELOPE. The collision stopping powers for the studied tissues were evaluated employing the formalism of ICRU Report 37 (1984 Stopping Powers for Electrons and Positrons (Bethesda, MD: ICRU)). The Bragg-Gray values of s(w,m) calculated with these ingredients range from about 0.98 (adipose tissue) to nearly 1.14 (cortical bone), displaying a rather small variation with beam quality. Excellent agreement, to within 0.1%, is found with stopping-power ratios reported by Siebers et al (2000a Phys. Med. Biol. 45 983-95) for cortical bone, inflated lung and spongiosa. In the case of cortical bone, s(w,m) changes approximately 2% when either ICRP or ICRU compositions are adopted, whereas the stopping-power ratios of lung, brain and adipose tissue are less sensitive to the selected composition. The mass density of lung also influences the calculated values of s(w,m), reducing them by around 1% (6 MV) and 2% (18 MV) when going from deflated to inflated lung.

  12. Monte Carlo based dosimetry for neutron capture therapy of brain tumors

    Science.gov (United States)

    Zaidi, Lilia; Belgaid, Mohamed; Khelifi, Rachid

    2016-11-01

    Boron Neutron Capture Therapy (BNCT) is a biologically targeted, radiation therapy for cancer which combines neutron irradiation with a tumor targeting agent labeled with a boron10 having a high thermal neutron capture cross section. The tumor area is subjected to the neutron irradiation. After a thermal neutron capture, the excited 11B nucleus fissions into an alpha particle and lithium recoil nucleus. The high Linear Energy Transfer (LET) emitted particles deposit their energy in a range of about 10μm, which is of the same order of cell diameter [1], at the same time other reactions due to neutron activation with body component are produced. In-phantom measurement of physical dose distribution is very important for BNCT planning validation. Determination of total absorbed dose requires complex calculations which were carried out using the Monte Carlo MCNP code [2].

  13. Monte Carlo based performance assessment of different animal PET architectures using pixellated CZT detectors

    Energy Technology Data Exchange (ETDEWEB)

    Visvikis, D. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France)]. E-mail: Visvikis.Dimitris@univ-brest.fr; Lefevre, T. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France); Lamare, F. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France); Kontaxakis, G. [ETSI Telecomunicacion Universidad Politecnica de Madrid, Ciudad Universitaria, s/n 28040, Madrid (Spain); Santos, A. [ETSI Telecomunicacion Universidad Politecnica de Madrid, Ciudad Universitaria, s/n 28040, Madrid (Spain); Darambara, D. [Department of Physics, School of Engineering and Physical Sciences, University of Surrey, Guildford (United Kingdom)

    2006-12-20

    The majority of present position emission tomography (PET) animal systems are based on the coupling of high-density scintillators and light detectors. A disadvantage of these detector configurations is the compromise between image resolution, sensitivity and energy resolution. In addition, current combined imaging devices are based on simply placing back-to-back and in axial alignment different apparatus without any significant level of software or hardware integration. The use of semiconductor CdZnTe (CZT) detectors is a promising alternative to scintillators for gamma-ray imaging systems. At the same time CZT detectors have the potential properties necessary for the construction of a truly integrated imaging device (PET/SPECT/CT). The aims of this study was to assess the performance of different small animal PET scanner architectures based on CZT pixellated detectors and compare their performance with that of state of the art existing PET animal scanners. Different scanner architectures were modelled using GATE (Geant4 Application for Tomographic Emission). Particular scanner design characteristics included an overall cylindrical scanner format of 8 and 24 cm in axial and transaxial field of view, respectively, and a temporal coincidence window of 8 ns. Different individual detector modules were investigated, considering pixel pitch down to 0.625 mm and detector thickness from 1 to 5 mm. Modified NEMA NU2-2001 protocols were used in order to simulate performance based on mouse, rat and monkey imaging conditions. These protocols allowed us to directly compare the performance of the proposed geometries with the latest generation of current small animal systems. Results attained demonstrate the potential for higher NECR with CZT based scanners in comparison to scintillator based animal systems.

  14. Fast online Monte Carlo-based IMRT planning for the MRI linear accelerator

    NARCIS (Netherlands)

    Bol, G.H.; Hissoiny, S.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2012-01-01

    The MRI accelerator, a combination of a 6 MV linear accelerator with a 1.5 T MRI, facilitates continuous patient anatomy updates regarding translations, rotations and deformations of targets and organs at risk. Accounting for these demands high speed, online intensity-modulated radiotherapy (IMRT) r

  15. A class of Monte-Carlo-based statistical algorithms for efficient detection of repolarization alternans.

    Science.gov (United States)

    Iravanian, Shahriar; Kanu, Uche B; Christini, David J

    2012-07-01

    Cardiac repolarization alternans is an electrophysiologic condition identified by a beat-to-beat fluctuation in action potential waveform. It has been mechanistically linked to instances of T-wave alternans, a clinically defined ECG alternation in T-wave morphology, and associated with the onset of cardiac reentry and sudden cardiac death. Many alternans detection algorithms have been proposed in the past, but the majority have been designed specifically for use with T-wave alternans. Action potential duration (APD) signals obtained from experiments (especially those derived from optical mapping) possess unique characteristics, which requires the development and use of a more appropriate alternans detection method. In this paper, we present a new class of algorithms, based on the Monte Carlo method, for the detection and quantitative measurement of alternans. Specifically, we derive a set of algorithms (one an analytical and more efficient version of the other) and compare its performance with the standard spectral method and the generalized likelihood ratio test algorithm using synthetic APD sequences and optical mapping data obtained from an alternans control experiment. We demonstrate the benefits of the new algorithm in the presence of Gaussian and Laplacian noise and frame-shift errors. The proposed algorithms are well suited for experimental applications, and furthermore, have low complexity and are implementable using fixed-point arithmetic, enabling potential use with implantable cardiac devices.

  16. Monte Carlo based statistical power analysis for mediation models: methods and software.

    Science.gov (United States)

    Zhang, Zhiyong

    2014-12-01

    The existing literature on statistical power analysis for mediation models often assumes data normality and is based on a less powerful Sobel test instead of the more powerful bootstrap test. This study proposes to estimate statistical power to detect mediation effects on the basis of the bootstrap method through Monte Carlo simulation. Nonnormal data with excessive skewness and kurtosis are allowed in the proposed method. A free R package called bmem is developed to conduct the power analysis discussed in this study. Four examples, including a simple mediation model, a multiple-mediator model with a latent mediator, a multiple-group mediation model, and a longitudinal mediation model, are provided to illustrate the proposed method.

  17. Effect of statistical fluctuation in Monte Carlo based photon beam dose calculation on gamma index evaluation.

    Science.gov (United States)

    Graves, Yan Jiang; Jia, Xun; Jiang, Steve B

    2013-03-21

    The γ-index test has been commonly adopted to quantify the degree of agreement between a reference dose distribution and an evaluation dose distribution. Monte Carlo (MC) simulation has been widely used for the radiotherapy dose calculation for both clinical and research purposes. The goal of this work is to investigate both theoretically and experimentally the impact of the MC statistical fluctuation on the γ-index test when the fluctuation exists in the reference, the evaluation, or both dose distributions. To the first order approximation, we theoretically demonstrated in a simplified model that the statistical fluctuation tends to overestimate γ-index values when existing in the reference dose distribution and underestimate γ-index values when existing in the evaluation dose distribution given the original γ-index is relatively large for the statistical fluctuation. Our numerical experiments using realistic clinical photon radiation therapy cases have shown that (1) when performing a γ-index test between an MC reference dose and a non-MC evaluation dose, the average γ-index is overestimated and the gamma passing rate decreases with the increase of the statistical noise level in the reference dose; (2) when performing a γ-index test between a non-MC reference dose and an MC evaluation dose, the average γ-index is underestimated when they are within the clinically relevant range and the gamma passing rate increases with the increase of the statistical noise level in the evaluation dose; (3) when performing a γ-index test between an MC reference dose and an MC evaluation dose, the gamma passing rate is overestimated due to the statistical noise in the evaluation dose and underestimated due to the statistical noise in the reference dose. We conclude that the γ-index test should be used with caution when comparing dose distributions computed with MC simulation.

  18. Monte-Carlo-based studies of a polarized positron source for International Linear Collider (ILC)

    Science.gov (United States)

    Dollan, Ralph; Laihem, Karim; Schälicke, Andreas

    2006-04-01

    The full exploitation of the physics potential of an International Linear Collider (ILC) requires the development of a polarized positron beam. New concepts of polarized positron sources are based on the development of circularly polarized photon sources. The polarized photons create electron-positron pairs in a thin target and transfer their polarization state to the outgoing leptons. To achieve a high level of positron polarization the understanding of the production mechanisms in the target is crucial. Therefore, a general framework for the simulation of polarized processes with GEANT4 is under development. In this contribution the current status of the project and its application to a study of the positron production process for the ILC is presented.

  19. Monte Carlo based studies of a polarized positron source for international linear collider (ILC).

    OpenAIRE

    Schälicke, A.; Dollan, R.; Laihem, K.

    2006-01-01

    The full exploitation of the physics potential of an International Linear Collider (ILC) requires the development of a polarized positron beam. New concepts of polarized positron sources are based on the development of circularly polarized photon sources. The polarized photons create electron-positron pairs in a thin target and transfer their polarization state to the outgoing leptons. To achieve a high level of positron polarization the understanding of the production mechanisms in the targe...

  20. Monte Carlo based NMR simulations of open fractures in porous media

    Science.gov (United States)

    Lukács, Tamás; Balázs, László

    2014-05-01

    According to the basic principles of nuclear magnetic resonance (NMR), a measurement's free induction decay curve has an exponential characteristic and its parameter is the transversal relaxation time, T2, given by the Bloch equations in rotating frame. In our simulations we are observing that particular case when the bulk's volume is neglectable to the whole system, the vertical movement is basically zero, hence the diffusion part of the T2 relation can be editted out. This small-apertured situations are common in sedimentary layers, and the smallness of the observed volume enable us to calculate with just the bulk relaxation and the surface relaxation. The simulation uses the Monte-Carlo method, so it is based on a random-walk generator which provides the brownian motions of the particles by uniformly distributed, pseudorandom generated numbers. An attached differential equation assures the bulk relaxation, the initial and the iterated conditions guarantee the simulation's replicability and enable having consistent estimations. We generate an initial geometry of a plain segment with known height, with given number of particles, the spatial distribution is set to equal to each simulation, and the surface-volume ratio remains at a constant value. It follows that to the given thickness of the open fracture, from the fitted curve's parameter, the surface relaxivity is determinable. The calculated T2 distribution curves are also indicating the inconstancy in the observed fracture situations. The effect of varying the height of the lamina at a constant diffusion coefficient also produces characteristic anomaly and for comparison we have run the simulation with the same initial volume, number of particles and conditions in spherical bulks, their profiles are clear and easily to understand. The surface relaxation enables us to estimate the interaction beetwen the materials of boundary with this two geometrically well-defined bulks, therefore the distribution takes as a basis in estimation of the porosity and can be use of identifying small-grained porous media.

  1. Markov chain Monte Carlo based analysis of post-translationally modified VDAC gating kinetics.

    Science.gov (United States)

    Tewari, Shivendra G; Zhou, Yifan; Otto, Bradley J; Dash, Ranjan K; Kwok, Wai-Meng; Beard, Daniel A

    2014-01-01

    The voltage-dependent anion channel (VDAC) is the main conduit for permeation of solutes (including nucleotides and metabolites) of up to 5 kDa across the mitochondrial outer membrane (MOM). Recent studies suggest that VDAC activity is regulated via post-translational modifications (PTMs). Yet the nature and effect of these modifications is not understood. Herein, single channel currents of wild-type, nitrosated, and phosphorylated VDAC are analyzed using a generalized continuous-time Markov chain Monte Carlo (MCMC) method. This developed method describes three distinct conducting states (open, half-open, and closed) of VDAC activity. Lipid bilayer experiments are also performed to record single VDAC activity under un-phosphorylated and phosphorylated conditions, and are analyzed using the developed stochastic search method. Experimental data show significant alteration in VDAC gating kinetics and conductance as a result of PTMs. The effect of PTMs on VDAC kinetics is captured in the parameters associated with the identified Markov model. Stationary distributions of the Markov model suggest that nitrosation of VDAC not only decreased its conductance but also significantly locked VDAC in a closed state. On the other hand, stationary distributions of the model associated with un-phosphorylated and phosphorylated VDAC suggest a reversal in channel conformation from relatively closed state to an open state. Model analyses of the nitrosated data suggest that faster reaction of nitric oxide with Cys-127 thiol group might be responsible for the biphasic effect of nitric oxide on basal VDAC conductance.

  2. Iterative reconstruction using a Monte Carlo based system transfer matrix for dedicated breast positron emission tomography.

    Science.gov (United States)

    Saha, Krishnendu; Straus, Kenneth J; Chen, Yu; Glick, Stephen J

    2014-08-28

    To maximize sensitivity, it is desirable that ring Positron Emission Tomography (PET) systems dedicated for imaging the breast have a small bore. Unfortunately, due to parallax error this causes substantial degradation in spatial resolution for objects near the periphery of the breast. In this work, a framework for computing and incorporating an accurate system matrix into iterative reconstruction is presented in an effort to reduce spatial resolution degradation towards the periphery of the breast. The GATE Monte Carlo Simulation software was utilized to accurately model the system matrix for a breast PET system. A strategy for increasing the count statistics in the system matrix computation and for reducing the system element storage space was used by calculating only a subset of matrix elements and then estimating the rest of the elements by using the geometric symmetry of the cylindrical scanner. To implement this strategy, polar voxel basis functions were used to represent the object, resulting in a block-circulant system matrix. Simulation studies using a breast PET scanner model with ring geometry demonstrated improved contrast at 45% reduced noise level and 1.5 to 3 times resolution performance improvement when compared to MLEM reconstruction using a simple line-integral model. The GATE based system matrix reconstruction technique promises to improve resolution and noise performance and reduce image distortion at FOV periphery compared to line-integral based system matrix reconstruction.

  3. Monte Carlo based geometrical model for efficiency calculation of an n-type HPGe detector.

    Science.gov (United States)

    Cabal, Fatima Padilla; Lopez-Pino, Neivy; Bernal-Castillo, Jose Luis; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D'Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar

    2010-12-01

    A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ((241)Am, (133)Ba, (22)Na, (60)Co, (57)Co, (137)Cs and (152)Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized.

  4. Monte-Carlo based prediction of radiochromic film response for hadrontherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Frisson, T. [Universite de Lyon, F-69622 Lyon (France); CREATIS-LRMN, INSA, Batiment Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Centre Leon Berrard - 28 rue Laennec, F-69373 Lyon Cedex 08 (France)], E-mail: frisson@creatis.insa-lyon.fr; Zahra, N. [Universite de Lyon, F-69622 Lyon (France); IPNL - CNRS/IN2P3 UMR 5822, Universite Lyon 1, Batiment Paul Dirac, 4 rue Enrico Fermi, F-69622 Villeurbanne Cedex (France); Centre Leon Berrard - 28 rue Laennec, F-69373 Lyon Cedex 08 (France); Lautesse, P. [Universite de Lyon, F-69622 Lyon (France); IPNL - CNRS/IN2P3 UMR 5822, Universite Lyon 1, Batiment Paul Dirac, 4 rue Enrico Fermi, F-69622 Villeurbanne Cedex (France); Sarrut, D. [Universite de Lyon, F-69622 Lyon (France); CREATIS-LRMN, INSA, Batiment Blaise Pascal, 7 avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Centre Leon Berrard - 28 rue Laennec, F-69373 Lyon Cedex 08 (France)

    2009-07-21

    A model has been developed to calculate MD-55-V2 radiochromic film response to ion irradiation. This model is based on photon film response and film saturation by high local energy deposition computed by Monte-Carlo simulation. We have studied the response of the film to photon irradiation and we proposed a calculation method for hadron beams.

  5. Monte-Carlo based prediction of radiochromic film response for hadrontherapy dosimetry

    Science.gov (United States)

    Frisson, T.; Zahra, N.; Lautesse, P.; Sarrut, D.

    2009-07-01

    A model has been developed to calculate MD-55-V2 radiochromic film response to ion irradiation. This model is based on photon film response and film saturation by high local energy deposition computed by Monte-Carlo simulation. We have studied the response of the film to photon irradiation and we proposed a calculation method for hadron beams.

  6. Monte Carlo based calibration of scintillation detectors for laboratory and in situ gamma ray measurements

    NARCIS (Netherlands)

    van der Graaf, E. R.; Limburg, J.; Koomans, R. L.; Tijs, M.

    The calibration of scintillation detectors for gamma radiation in a well characterized setup can be transferred to other geometries using Monte Carlo simulations to account for the differences between the calibration and the other geometry. In this study a calibration facility was used that is

  7. A Monte Carlo-based treatment planning tool for proton therapy

    Science.gov (United States)

    Mairani, A.; Böhlen, T. T.; Schiavi, A.; Tessonnier, T.; Molinelli, S.; Brons, S.; Battistoni, G.; Parodi, K.; Patera, V.

    2013-04-01

    In the field of radiotherapy, Monte Carlo (MC) particle transport calculations are recognized for their superior accuracy in predicting dose and fluence distributions in patient geometries compared to analytical algorithms which are generally used for treatment planning due to their shorter execution times. In this work, a newly developed MC-based treatment planning (MCTP) tool for proton therapy is proposed to support treatment planning studies and research applications. It allows for single-field and simultaneous multiple-field optimization in realistic treatment scenarios and is based on the MC code FLUKA. Relative biological effectiveness (RBE)-weighted dose is optimized either with the common approach using a constant RBE of 1.1 or using a variable RBE according to radiobiological input tables. A validated reimplementation of the local effect model was used in this work to generate radiobiological input tables. Examples of treatment plans in water phantoms and in patient-CT geometries together with an experimental dosimetric validation of the plans are presented for clinical treatment parameters as used at the Italian National Center for Oncological Hadron Therapy. To conclude, a versatile MCTP tool for proton therapy was developed and validated for realistic patient treatment scenarios against dosimetric measurements and commercial analytical TP calculations. It is aimed to be used in future for research and to support treatment planning at state-of-the-art ion beam therapy facilities.

  8. Iterative reconstruction using a Monte Carlo based system transfer matrix for dedicated breast positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Krishnendu [Ohio Medical Physics Consulting, Dublin, Ohio 43017 (United States); Straus, Kenneth J.; Glick, Stephen J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Chen, Yu. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States)

    2014-08-28

    To maximize sensitivity, it is desirable that ring Positron Emission Tomography (PET) systems dedicated for imaging the breast have a small bore. Unfortunately, due to parallax error this causes substantial degradation in spatial resolution for objects near the periphery of the breast. In this work, a framework for computing and incorporating an accurate system matrix into iterative reconstruction is presented in an effort to reduce spatial resolution degradation towards the periphery of the breast. The GATE Monte Carlo Simulation software was utilized to accurately model the system matrix for a breast PET system. A strategy for increasing the count statistics in the system matrix computation and for reducing the system element storage space was used by calculating only a subset of matrix elements and then estimating the rest of the elements by using the geometric symmetry of the cylindrical scanner. To implement this strategy, polar voxel basis functions were used to represent the object, resulting in a block-circulant system matrix. Simulation studies using a breast PET scanner model with ring geometry demonstrated improved contrast at 45% reduced noise level and 1.5 to 3 times resolution performance improvement when compared to MLEM reconstruction using a simple line-integral model. The GATE based system matrix reconstruction technique promises to improve resolution and noise performance and reduce image distortion at FOV periphery compared to line-integral based system matrix reconstruction.

  9. Quality assessment of Monte Carlo based system response matrices in PET

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, J.; Gillam, J.E. [Valencia Univ. (Spain). Inst. de Fisica Corpuscular; Rafecas, M. [Valencia Univ. (Spain). Inst. de Fisica Corpuscular; Valencia Univ. (Spain). Dept. de Fisica Atomica, Molecular y Nuclear

    2011-07-01

    Iterative methods are currently accepted as the gold standard image reconstruction methods in nuclear medicine. The quality of the final reconstructed image greatly depends on how well physical processes are modelled in the System-Response- Matrix (SRM). The SRM can be obtained using experimental measurements, or calculated using Monte-Carlo (MC) or analytical methods. Nevertheless, independent on the method, the SRM is always contaminated by a certain level of error. MC based methods have recently gained popularity in calculation of the SRM due to the significant increase in computer power exhibited by regular commercial computers. MC methods can produce high accuracy results, but are subject to statistical noise, which affects the precision of the results. By increasing the number of annihilations simulated, the level of noise observed in the SRM decreases, at the additional cost of increased simulation time and increased file size necessary to store the SRM. The latter also has a negative impact on reconstruction time. A study on the noise of the SRM has been performed from a spatial point of view, identifying specific regions subject to higher levels of noise. This study will enable the calculation of SRM with different levels of statistics depending on the spatial location. A quantitative comparison of images, reconstructed using different SRM realizations, with similar and different levels of statistical quality, has been presented. (orig.)

  10. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    Science.gov (United States)

    Renner, F; Wulff, J; Kapsch, R-P; Zink, K

    2015-10-01

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as the energy of the radiation source and the underlying photon cross sections as well as the I-value of media involved in the simulation. The combined standard uncertainty of the Monte Carlo calculation yields 0.78% as a conservative estimation. The result of the calculation is close to the experimental result and with each combined standard uncertainty  benchmark other Monte Carlo codes for the calculation of absorbed dose in radiotherapy.

  11. Monte Carlo-based multiphysics coupling analysis of x-ray pulsar telescope

    Science.gov (United States)

    Li, Liansheng; Deng, Loulou; Mei, Zhiwu; Zuo, Fuchang; Zhou, Hao

    2015-10-01

    X-ray pulsar telescope (XPT) is a complex optical payload, which involves optical, mechanical, electrical and thermal disciplines. The multiphysics coupling analysis (MCA) plays an important role in improving the in-orbit performance. However, the conventional MCA methods encounter two serious problems in dealing with the XTP. One is that both the energy and reflectivity information of X-ray can't be taken into consideration, which always misunderstands the essence of XPT. Another is that the coupling data can't be transferred automatically among different disciplines, leading to computational inefficiency and high design cost. Therefore, a new MCA method for XPT is proposed based on the Monte Carlo method and total reflective theory. The main idea, procedures and operational steps of the proposed method are addressed in detail. Firstly, it takes both the energy and reflectivity information of X-ray into consideration simultaneously. And formulate the thermal-structural coupling equation and multiphysics coupling analysis model based on the finite element method. Then, the thermalstructural coupling analysis under different working conditions has been implemented. Secondly, the mirror deformations are obtained using construction geometry function. Meanwhile, the polynomial function is adopted to fit the deformed mirror and meanwhile evaluate the fitting error. Thirdly, the focusing performance analysis of XPT can be evaluated by the RMS. Finally, a Wolter-I XPT is taken as an example to verify the proposed MCA method. The simulation results show that the thermal-structural coupling deformation is bigger than others, the vary law of deformation effect on the focusing performance has been obtained. The focusing performances of thermal-structural, thermal, structural deformations have degraded 30.01%, 14.35% and 7.85% respectively. The RMS of dispersion spot are 2.9143mm, 2.2038mm and 2.1311mm. As a result, the validity of the proposed method is verified through comparing the simulation results and experiments, which can be employed in the reliability-based design of XPT.

  12. Graphene oxide based sol-gel stainless steel fiber for the headspace solid-phase microextraction of organophosphate ester flame retardants in water samples.

    Science.gov (United States)

    Jin, Tingting; Cheng, Jing; Cai, Cuicui; Cheng, Min; Wu, Shiju; Zhou, Hongbin

    2016-07-29

    In this paper, graphene oxide was coated onto a stainless steel wire through sol-gel technique and it was used as a solid phase microextraction (SPME) fiber. The prepared fiber was characterized by scanning electron microscopy (SEM), which displayed that the fiber had crinkled surface and porous structure The application of the fiber was evaluated through the headspace SPME of nine organophosphate ester flame retardants (OPFRs) with different characteristics in water samples followed by gas chromatography and nitrogen-phosphorous detector (GC/NPD). The major factors influencing the extraction efficiency, including the extraction and desorption conditions, were studied and optimized. Under the optimum conditions, the proposed method was evaluated, and applied to the analysis of organophosphate ester flame retardants in real environmental water samples. The results demonstrated the HS-SPME method based on GO sol-gel fiber had good linearity (R>0.9928), and limits of detection (1.4-135.6ngL(-1)), high repeatability (RSDsol-gel fiber displayed bigger extraction capability than the commercial PDMS fiber and the pure sol-gel fiber for both polar and apolar organophosphate esters, especially for the OPFRs containing benzene rings.

  13. Modification and calibration of a passive air sampler for monitoring vapor and particulate phase brominated flame retardants in indoor air: application to car interiors.

    Science.gov (United States)

    Abdallah, Mohamed Abou-Elwafa; Harrad, Stuart

    2010-04-15

    A passive air sampler was modified to monitor both vapor and particulate phase brominated flame retardants (BFRs) in indoor air using polyurethane foam disks and glass fiber filters (GFF). Significant correlation (p GFF was investigated using environmental scanning electron microscopy which revealed gravitational deposition of particles as the main mechanism involved. The developed sampler was applied to monitor BFR concentrations in 21 cars. Average concentrations of SigmaHBCDs, TBBP-A, and Sigmatetra-deca BDEs were 400, 3, and 2200 pg m(-3) in cabins and 400, 1, and 1600 pg m(-3) in trunks. No significant differences (p < 0.05) were observed between levels of SigmaHBCDs and Sigmatrito hexa- BDEs in cabins and trunks. However, TBBP-A, BDE-209, and SigmaPBDEs concentrations were significantly higher in vehicle cabins.

  14. Magnetic solid-phase extraction of brominated flame retardants from environmental waters with graphene-doped Fe3O4 nanocomposites.

    Science.gov (United States)

    Yang, Jing; Qiao, Jun-qin; Cui, Shi-hai; Li, Jia-yuan; Zhu, Jin-jin; Yin, He-xing; Zhan, Cheng-yan; Lian, Hong-zhen

    2015-06-01

    Graphene-doped Fe3O4 nanocomposites were prepared by a solvothermal reaction of an iron source with graphene. The nanocomposites were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, superconducting quantum interference, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This nanomaterial has been used as a magnetic solid-phase extraction sorbent to extract trace brominated flame retardants from environmental waters. Various extraction parameters were optimized including dosage and reusability of the nanocomposites, and pH of sample matrix. The reliability of the magnetic solid-phase extraction protocol based on graphene-doped Fe3O4 nanocomposites was evaluated by investigating the recoveries of 2,4,6-tribromophenol, tetrabromobisphenol A, 4-bromodiphenyl ether, and 4,4'-dibromodiphenyl ether in water samples. Good recoveries (85.0-105.0%) were achieved with the relative standard deviation ranging from 1.1-7.1%. Moreover, it is speculated from characterization and magnetic solid-phase extraction experiment that there is not only π-π stacking but also possible hydrophobic interaction between the graphene-doped Fe3O4 nanocomposites and analytes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Determination of organophosphorus flame retardants in fish by pressurized liquid extraction using aqueous solutions and solid-phase microextraction coupled with gas chromatography-flame photometric detector.

    Science.gov (United States)

    Gao, Zhanqi; Deng, Yuehua; Yuan, Wenting; He, Huan; Yang, Shaogui; Sun, Cheng

    2014-10-31

    A novel method was developed for the determination of organophosphorus flame retardants (PFRs) in fish. The method consists of a combination of pressurized liquid extraction (PLE) using aqueous solutions and solid-phase microextraction (SPME), followed by gas chromatography-flame photometric detector (GC-FPD). The experimental parameters that influenced extraction efficiency were systematically evaluated. The optimal responses were observed by extracting 1g of fish meat with the solution of water:acetonitrile (90:10, v/v) at 150°C for 5min and acid-washed silica gel used as lipid sorbent. The obtained extract was then analyzed by SPME coupled with GC-FPD without any additional clean-up steps. Under the optimal conditions, the proposed procedure showed a wide linear range (0.90-5000ngg(-1)) obtained by analyzing the spiked fish samples with increasing concentrations of PFRs and correlation coefficient (R) ranged from 0.9900 to 0.9992. The detection limits (S/N=3) were in the range of 0.010-0.208ngg(-1) with standard deviations (RSDs) ranging from 2.0% to 9.0%. The intra-day and inter-day variations were less than 9.0% and 7.8%, respectively. The proposed method was successfully applied to the determination of PFRs in real fish samples with recoveries varying from 79.8% to 107.3%. The results demonstrate that the proposed method is highly effective for analyzing PFRs in fish samples.

  16. Retardance and flicker modeling and characterization of electro-optic linear retarders by averaged Stokes polarimetry.

    Science.gov (United States)

    Martínez, Francisco J; Márquez, Andrés; Gallego, Sergi; Francés, Jorge; Pascual, Inmaculada; Beléndez, Augusto

    2014-02-15

    A polarimetric method for the measurement of linear retardance in the presence of phase fluctuations is presented. This can be applied to electro-optic devices behaving as variable linear retarders. The method is based on an extended Mueller matrix model for the linear retarder containing the time-averaged effects of the instabilities. As a result, an averaged Stokes polarimetry technique is proposed to characterize both the retardance and its flicker magnitude. Predictive capability of the approach is experimentally demonstrated, validating the model and the calibration technique. The approach is applied to liquid crystal on silicon displays (LCoS) using a commercial Stokes polarimeter. Both the magnitude of the average retardance and the amplitude of its fluctuation are obtained for each gray level value addressed, thus enabling a complete phase characterization of the LCoS.

  17. Solid Phase Synthesis of Anhydrous Zinc Borate from Zinc and Boron Oxide and Utilization as a Flame Retardant in Dye and Textile

    OpenAIRE

    AYAR, Barış; GÜRÜ, Metin; ÇAKANYILDIRIM, Çetin

    2014-01-01

    Durability of materials to flame and stability at high temperatures are very important in order to increase the field of use. Non-flammability is not the only requirement materials should not have toxic gas products during the burning, also. Anhydrous zinc borate was chosen as flame retardant due to its advantages, such as; light weight, high melting point, low thermal expansion, and intrinsic smoke suppressant and corrosion resistance properties. For the synthesis, metallic zinc and anhydrou...

  18. Fire retardants for wood

    Directory of Open Access Journals (Sweden)

    Vlatka Jirouš-Rajković

    2009-06-01

    Full Text Available Along with many advantages, wood as traditional building material also has some disadvantages. One of them is the flammability. The most usual way to improve the fire performance of wood is by treating it with fire retardants that can be applied to wood composite products during manufacture, pressure impregnated into solid wood or wood products or added as a paint or surface coating. Fire retardants are formulated to control ignition, flame spread on the wood surface and to reduce the amount of heat released from wood. Fire retardants cannot make wood non combustible. According to the European reaction-to-fire “Euroclasses”classification system for construction products, wood treated with fire retardant can meet the requirements of Euroclass B, whereas ordinary wood products typically fall into class D. This article attempts to bring together information related to the burning of wood, fire performance of wood, types of fire retardants and mechanism of fire retardancy. Fire retardant coatings and chemical impregnation by pressure-treating are described separately.

  19. X linked mental retardation.

    Science.gov (United States)

    Rejeb, Imen; Ben Jemaa, Lamia; Chaabouni, Habiba

    2009-05-01

    Mental retardation (MR) is a group of heterogeneous clinical conditions. There are more than 900 genetic disorders associated with MR and it affects around 3% of the general population. Many MR conditions described are syndromic, fragile X syndrome being the most common clinical entity among them. X linked mental retardation (XLMR) is subdivided in two categories: syndromic XLMR (MRXS) when MR is associated with clinical features and non-syndromic XLMR (MRX) when MR is isolated. The aim of this systematic review of the literature was to join together the results of several studies related to X linked mental retardation and to present various genes implicated in this disease. In this review, focus has been given on genes implicated in mental retardation, the clinical data and on phenotype-genotype correlations. An exhaustive electronic and library research of the recent literature was carried out on the Web sites "Science Direct" and "Interscience Wiley". The key words used were "mental retardation", "X chromosome", "gene", "syndromic mental retardation", "non-syndromic mental retardation". In this review a number of X linked genes, the clinical features associated with the gene abnormality, and the prevalence of the disease gene are discussed. We classified these genes by order of their first implication in MR. A table presented on the XLMR Update Web site who list the 82 known XLMR genes is available as XLMR Genes and corresponding proteins.

  20. Two computational approaches for Monte Carlo based shutdown dose rate calculation with applications to the JET fusion machine

    Energy Technology Data Exchange (ETDEWEB)

    Petrizzi, L.; Batistoni, P.; Migliori, S. [Associazione EURATOM ENEA sulla Fusione, Frascati (Roma) (Italy); Chen, Y.; Fischer, U.; Pereslavtsev, P. [Association FZK-EURATOM Forschungszentrum Karlsruhe (Germany); Loughlin, M. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxfordshire, OX (United Kingdom); Secco, A. [Nice Srl Via Serra 33 Camerano Casasco AT (Italy)

    2003-07-01

    In deuterium-deuterium (D-D) and deuterium-tritium (D-T) fusion plasmas neutrons are produced causing activation of JET machine components. For safe operation and maintenance it is important to be able to predict the induced activation and the resulting shut down dose rates. This requires a suitable system of codes which is capable of simulating both the neutron induced material activation during operation and the decay gamma radiation transport after shut-down in the proper 3-D geometry. Two methodologies to calculate the dose rate in fusion devices have been developed recently and applied to fusion machines, both using the MCNP Monte Carlo code. FZK has developed a more classical approach, the rigorous 2-step (R2S) system in which MCNP is coupled to the FISPACT inventory code with an automated routing. ENEA, in collaboration with the ITER Team, has developed an alternative approach, the direct 1 step method (D1S). Neutron and decay gamma transport are handled in one single MCNP run, using an ad hoc cross section library. The intention was to tightly couple the neutron induced production of a radio-isotope and the emission of its decay gammas for an accurate spatial distribution and a reliable calculated statistical error. The two methods have been used by the two Associations to calculate the dose rate in five positions of JET machine, two inside the vacuum chamber and three outside, at cooling times between 1 second and 1 year after shutdown. The same MCNP model and irradiation conditions have been assumed. The exercise has been proposed and financed in the frame of the Fusion Technological Program of the JET machine. The scope is to supply the designers with the most reliable tool and data to calculate the dose rate on fusion machines. Results showed that there is a good agreement: the differences range between 5-35%. The next step to be considered in 2003 will be an exercise in which the comparison will be done with dose-rate data from JET taken during and shortly after the deuterium-tritium experiment (DTE1) in 1997. Large computing power, both in terms of amount of data handling and storage and the CPU computing time is needed by the two methods, partly due to the complexity of the problem. With parallel versions of the MCNP code, running on two different platforms, a satisfying accuracy of the calculation has been reached in reasonable times. (authors)

  1. Patient-specific Monte Carlo-based dose-kernel approach for inverse planning in afterloading brachytherapy.

    Science.gov (United States)

    D'Amours, Michel; Pouliot, Jean; Dagnault, Anne; Verhaegen, Frank; Beaulieu, Luc

    2011-12-01

    Brachytherapy planning software relies on the Task Group report 43 dosimetry formalism. This formalism, based on a water approximation, neglects various heterogeneous materials present during treatment. Various studies have suggested that these heterogeneities should be taken into account to improve the treatment quality. The present study sought to demonstrate the feasibility of incorporating Monte Carlo (MC) dosimetry within an inverse planning algorithm to improve the dose conformity and increase the treatment quality. The method was based on precalculated dose kernels in full patient geometries, representing the dose distribution of a brachytherapy source at a single dwell position using MC simulations and the Geant4 toolkit. These dose kernels are used by the inverse planning by simulated annealing tool to produce a fast MC-based plan. A test was performed for an interstitial brachytherapy breast treatment using two different high-dose-rate brachytherapy sources: the microSelectron iridium-192 source and the electronic brachytherapy source Axxent operating at 50 kVp. A research version of the inverse planning by simulated annealing algorithm was combined with MC to provide a method to fully account for the heterogeneities in dose optimization, using the MC method. The effect of the water approximation was found to depend on photon energy, with greater dose attenuation for the lower energies of the Axxent source compared with iridium-192. For the latter, an underdosage of 5.1% for the dose received by 90% of the clinical target volume was found. A new method to optimize afterloading brachytherapy plans that uses MC dosimetric information was developed. Including computed tomography-based information in MC dosimetry in the inverse planning process was shown to take into account the full range of scatter and heterogeneity conditions. This led to significant dose differences compared with the Task Group report 43 approach for the Axxent source. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Patient-Specific Monte Carlo-Based Dose-Kernel Approach for Inverse Planning in Afterloading Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    D' Amours, Michel [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de l' Universite Laval, Hotel-Dieu de Quebec, Quebec, QC (Canada); Department of Physics, Physics Engineering, and Optics, Universite Laval, Quebec, QC (Canada); Pouliot, Jean [Department of Radiation Oncology, University of California, San Francisco, School of Medicine, San Francisco, CA (United States); Dagnault, Anne [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de l' Universite Laval, Hotel-Dieu de Quebec, Quebec, QC (Canada); Verhaegen, Frank [Department of Radiation Oncology, Maastro Clinic, GROW Research Institute, Maastricht University Medical Centre, Maastricht (Netherlands); Department of Oncology, McGill University, Montreal, QC (Canada); Beaulieu, Luc, E-mail: beaulieu@phy.ulaval.ca [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de l' Universite Laval, Hotel-Dieu de Quebec, Quebec, QC (Canada); Department of Physics, Physics Engineering, and Optics, Universite Laval, Quebec, QC (Canada)

    2011-12-01

    Purpose: Brachytherapy planning software relies on the Task Group report 43 dosimetry formalism. This formalism, based on a water approximation, neglects various heterogeneous materials present during treatment. Various studies have suggested that these heterogeneities should be taken into account to improve the treatment quality. The present study sought to demonstrate the feasibility of incorporating Monte Carlo (MC) dosimetry within an inverse planning algorithm to improve the dose conformity and increase the treatment quality. Methods and Materials: The method was based on precalculated dose kernels in full patient geometries, representing the dose distribution of a brachytherapy source at a single dwell position using MC simulations and the Geant4 toolkit. These dose kernels are used by the inverse planning by simulated annealing tool to produce a fast MC-based plan. A test was performed for an interstitial brachytherapy breast treatment using two different high-dose-rate brachytherapy sources: the microSelectron iridium-192 source and the electronic brachytherapy source Axxent operating at 50 kVp. Results: A research version of the inverse planning by simulated annealing algorithm was combined with MC to provide a method to fully account for the heterogeneities in dose optimization, using the MC method. The effect of the water approximation was found to depend on photon energy, with greater dose attenuation for the lower energies of the Axxent source compared with iridium-192. For the latter, an underdosage of 5.1% for the dose received by 90% of the clinical target volume was found. Conclusion: A new method to optimize afterloading brachytherapy plans that uses MC dosimetric information was developed. Including computed tomography-based information in MC dosimetry in the inverse planning process was shown to take into account the full range of scatter and heterogeneity conditions. This led to significant dose differences compared with the Task Group report 43 approach for the Axxent source.

  3. Monte Carlo-based subgrid parameterization of vertical velocity and stratiform cloud microphysics in ECHAM5.5-HAM2

    Directory of Open Access Journals (Sweden)

    J. Tonttila

    2013-08-01

    Full Text Available A new method for parameterizing the subgrid variations of vertical velocity and cloud droplet number concentration (CDNC is presented for general circulation models (GCMs. These parameterizations build on top of existing parameterizations that create stochastic subgrid cloud columns inside the GCM grid cells, which can be employed by the Monte Carlo independent column approximation approach for radiative transfer. The new model version adds a description for vertical velocity in individual subgrid columns, which can be used to compute cloud activation and the subgrid distribution of the number of cloud droplets explicitly. Autoconversion is also treated explicitly in the subcolumn space. This provides a consistent way of simulating the cloud radiative effects with two-moment cloud microphysical properties defined at subgrid scale. The primary impact of the new parameterizations is to decrease the CDNC over polluted continents, while over the oceans the impact is smaller. Moreover, the lower CDNC induces a stronger autoconversion of cloud water to rain. The strongest reduction in CDNC and cloud water content over the continental areas promotes weaker shortwave cloud radiative effects (SW CREs even after retuning the model. However, compared to the reference simulation, a slightly stronger SW CRE is seen e.g. over mid-latitude oceans, where CDNC remains similar to the reference simulation, and the in-cloud liquid water content is slightly increased after retuning the model.

  4. Optimisation of Simultaneous Tl-201/Tc-99m Dual Isotope Reconstruction with Monte-Carlo-Based Scatter Correction

    Directory of Open Access Journals (Sweden)

    Tuija Kangasmaa

    2012-01-01

    Full Text Available Simultaneous Tl-201/Tc-99m dual isotope myocardial perfusion SPECT is seriously hampered by down-scatter from Tc-99m into the Tl-201 energy window. This paper presents and optimises the ordered-subsets-expectation-maximisation-(OS-EM- based reconstruction algorithm, which corrects the down-scatter using an efficient Monte Carlo (MC simulator. The algorithm starts by first reconstructing the Tc-99m image with attenuation, collimator response, and MC-based scatter correction. The reconstructed Tc-99m image is then used as an input for an efficient MC-based down-scatter simulation of Tc-99m photons into the Tl-201 window. This down-scatter estimate is finally used in the Tl-201 reconstruction to correct the crosstalk between the two isotopes. The mathematical 4D NCAT phantom and physical cardiac phantoms were used to optimise the number of OS-EM iterations where the scatter estimate is updated and the number of MC simulated photons. The results showed that two scatter update iterations and 105 simulated photons are enough for the Tc-99m and Tl-201 reconstructions, whereas 106 simulated photons are needed to generate good quality down-scatter estimates. With these parameters, the entire Tl-201/Tc-99m dual isotope reconstruction can be accomplished in less than 3 minutes.

  5. Monte Carlo-based fluorescence molecular tomography reconstruction method accelerated by a cluster of graphic processing units.

    Science.gov (United States)

    Quan, Guotao; Gong, Hui; Deng, Yong; Fu, Jianwei; Luo, Qingming

    2011-02-01

    High-speed fluorescence molecular tomography (FMT) reconstruction for 3-D heterogeneous media is still one of the most challenging problems in diffusive optical fluorescence imaging. In this paper, we propose a fast FMT reconstruction method that is based on Monte Carlo (MC) simulation and accelerated by a cluster of graphics processing units (GPUs). Based on the Message Passing Interface standard, we modified the MC code for fast FMT reconstruction, and different Green's functions representing the flux distribution in media are calculated simultaneously by different GPUs in the cluster. A load-balancing method was also developed to increase the computational efficiency. By applying the Fréchet derivative, a Jacobian matrix is formed to reconstruct the distribution of the fluorochromes using the calculated Green's functions. Phantom experiments have shown that only 10 min are required to get reconstruction results with a cluster of 6 GPUs, rather than 6 h with a cluster of multiple dual opteron CPU nodes. Because of the advantages of high accuracy and suitability for 3-D heterogeneity media with refractive-index-unmatched boundaries from the MC simulation, the GPU cluster-accelerated method provides a reliable approach to high-speed reconstruction for FMT imaging.

  6. Posture-specific phantoms representing female and male adults in Monte Carlo-based simulations for radiological protection

    Science.gov (United States)

    Cassola, V. F.; Kramer, R.; Brayner, C.; Khoury, H. J.

    2010-08-01

    Does the posture of a patient have an effect on the organ and tissue absorbed doses caused by x-ray examinations? This study aims to find the answer to this question, based on Monte Carlo (MC) simulations of commonly performed x-ray examinations using adult phantoms modelled to represent humans in standing as well as in the supine posture. The recently published FASH (female adult mesh) and MASH (male adult mesh) phantoms have the standing posture. In a first step, both phantoms were updated with respect to their anatomy: glandular tissue was separated from adipose tissue in the breasts, visceral fat was separated from subcutaneous fat, cartilage was segmented in ears, nose and around the thyroid, and the mass of the right lung is now 15% greater than the left lung. The updated versions are called FASH2_sta and MASH2_sta (sta = standing). Taking into account the gravitational effects on organ position and fat distribution, supine versions of the FASH2 and the MASH2 phantoms have been developed in this study and called FASH2_sup and MASH2_sup. MC simulations of external whole-body exposure to monoenergetic photons and partial-body exposure to x-rays have been made with the standing and supine FASH2 and MASH2 phantoms. For external whole-body exposure for AP and PA projection with photon energies above 30 keV, the effective dose did not change by more than 5% when the posture changed from standing to supine or vice versa. Apart from that, the supine posture is quite rare in occupational radiation protection from whole-body exposure. However, in the x-ray diagnosis supine posture is frequently used for patients submitted to examinations. Changes of organ absorbed doses up to 60% were found for simulations of chest and abdomen radiographs if the posture changed from standing to supine or vice versa. A further increase of differences between posture-specific organ and tissue absorbed doses with increasing whole-body mass is to be expected.

  7. Monte Carlo-Based Dose Calculation in Postprostatectomy Image-Guided Intensity Modulated Radiotherapy: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Ashley Rankine

    2015-01-01

    Full Text Available Step-and-shoot (S&S intensity-modulated radiotherapy (IMRT using the XiO treatment planning system (TPS has been routinely used for patients receiving postprostatectomy radiotherapy (PPRT. After installing the Monaco, a pilot study was undertaken with five patients to compare XiO with Monaco (V2.03 TPS for PPRT with respect to plan quality for S&S as well as volumetric-modulated arc therapy (VMAT. Monaco S&S showed higher mean clinical target volume (CTV coverage (99.85% than both XiO S&S (97.98%, P = 0.04 and Monaco VMAT (99.44, P = 0.02. Rectal V60Gy volumes were lower for Monaco S&S compared to XiO (46.36% versus 58.06%, P = 0.001 and Monaco VMAT (46.36% versus 54.66%, P = 0.02. Rectal V60Gy volume was lowest for Monaco S&S and superior to XiO (mean 19.89% versus 31.25%, P = 0.02. Rectal V60Gy volumes were lower for Monaco VMAT compared to XiO (21.09% versus 31.25%, P = 0.02. Other organ-at-risk (OAR parameters were comparable between TPSs. Compared to XiO S&S, Monaco S&S plans had fewer segments (78.6 versus 116.8 segments, P = 0.02, lower total monitor units (MU (677.6 MU versus 770.7 MU, P = 0.01, and shorter beam-on times (5.7 min versus 7.6 min, P = 0.03. This pilot study suggests that Monaco S&S improves CTV coverage, OAR doses, and planning and treatment times for PPRT.

  8. Monte Carlo based approach to the LS–NaI 4πβ–γ anticoincidence extrapolation and uncertainty.

    Science.gov (United States)

    Fitzgerald, R

    2016-03-01

    The 4πβ–γ anticoincidence method is used for the primary standardization of β−, β+, electron capture (EC), α, and mixed-mode radionuclides. Efficiency extrapolation using one or more γ ray coincidence gates is typically carried out by a low-order polynomial fit. The approach presented here is to use a Geant4-based Monte Carlo simulation of the detector system to analyze the efficiency extrapolation. New code was developed to account for detector resolution, direct γ ray interaction with the PMT, and implementation of experimental β-decay shape factors. The simulation was tuned to 57Co and 60Co data, then tested with 99mTc data, and used in measurements of 18F, 129I, and 124I. The analysis method described here offers a more realistic activity value and uncertainty than those indicated from a least-squares fit alone.

  9. SU-E-T-175: Clinical Evaluations of Monte Carlo-Based Inverse Treatment Plan Optimization for Intensity Modulated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Y; Li, Y; Tian, Z; Gu, X; Jiang, S; Jia, X [UT Southwestern Medical Center, Dallas, TX (United States)

    2015-06-15

    Purpose: Pencil-beam or superposition-convolution type dose calculation algorithms are routinely used in inverse plan optimization for intensity modulated radiation therapy (IMRT). However, due to their limited accuracy in some challenging cases, e.g. lung, the resulting dose may lose its optimality after being recomputed using an accurate algorithm, e.g. Monte Carlo (MC). It is the objective of this study to evaluate the feasibility and advantages of a new method to include MC in the treatment planning process. Methods: We developed a scheme to iteratively perform MC-based beamlet dose calculations and plan optimization. In the MC stage, a GPU-based dose engine was used and the particle number sampled from a beamlet was proportional to its optimized fluence from the previous step. We tested this scheme in four lung cancer IMRT cases. For each case, the original plan dose, plan dose re-computed by MC, and dose optimized by our scheme were obtained. Clinically relevant dosimetric quantities in these three plans were compared. Results: Although the original plan achieved a satisfactory PDV dose coverage, after re-computing doses using MC method, it was found that the PTV D95% were reduced by 4.60%–6.67%. After re-optimizing these cases with our scheme, the PTV coverage was improved to the same level as in the original plan, while the critical OAR coverages were maintained to clinically acceptable levels. Regarding the computation time, it took on average 144 sec per case using only one GPU card, including both MC-based beamlet dose calculation and treatment plan optimization. Conclusion: The achieved dosimetric gains and high computational efficiency indicate the feasibility and advantages of the proposed MC-based IMRT optimization method. Comprehensive validations in more patient cases are in progress.

  10. Quantifying acoustic doppler current profiler discharge uncertainty: A Monte Carlo based tool for moving-boat measurements

    Science.gov (United States)

    Mueller, David S.

    2017-01-01

    This paper presents a method using Monte Carlo simulations for assessing uncertainty of moving-boat acoustic Doppler current profiler (ADCP) discharge measurements using a software tool known as QUant, which was developed for this purpose. Analysis was performed on 10 data sets from four Water Survey of Canada gauging stations in order to evaluate the relative contribution of a range of error sources to the total estimated uncertainty. The factors that differed among data sets included the fraction of unmeasured discharge relative to the total discharge, flow nonuniformity, and operator decisions about instrument programming and measurement cross section. As anticipated, it was found that the estimated uncertainty is dominated by uncertainty of the discharge in the unmeasured areas, highlighting the importance of appropriate selection of the site, the instrument, and the user inputs required to estimate the unmeasured discharge. The main contributor to uncertainty was invalid data, but spatial inhomogeneity in water velocity and bottom-track velocity also contributed, as did variation in the edge velocity, uncertainty in the edge distances, edge coefficients, and the top and bottom extrapolation methods. To a lesser extent, spatial inhomogeneity in the bottom depth also contributed to the total uncertainty, as did uncertainty in the ADCP draft at shallow sites. The estimated uncertainties from QUant can be used to assess the adequacy of standard operating procedures. They also provide quantitative feedback to the ADCP operators about the quality of their measurements, indicating which parameters are contributing most to uncertainty, and perhaps even highlighting ways in which uncertainty can be reduced. Additionally, QUant can be used to account for self-dependent error sources such as heading errors, which are a function of heading. The results demonstrate the importance of a Monte Carlo method tool such as QUant for quantifying random and bias errors when evaluating the uncertainty of moving-boat ADCP measurements.

  11. Optimisation of simultaneous tl-201/tc-99m dual isotope reconstruction with monte-carlo-based scatter correction.

    Science.gov (United States)

    Kangasmaa, Tuija; Kuikka, Jyrki; Sohlberg, Antti

    2012-01-01

    Simultaneous Tl-201/Tc-99m dual isotope myocardial perfusion SPECT is seriously hampered by down-scatter from Tc-99m into the Tl-201 energy window. This paper presents and optimises the ordered-subsets-expectation-maximisation-(OS-EM-) based reconstruction algorithm, which corrects the down-scatter using an efficient Monte Carlo (MC) simulator. The algorithm starts by first reconstructing the Tc-99m image with attenuation, collimator response, and MC-based scatter correction. The reconstructed Tc-99m image is then used as an input for an efficient MC-based down-scatter simulation of Tc-99m photons into the Tl-201 window. This down-scatter estimate is finally used in the Tl-201 reconstruction to correct the crosstalk between the two isotopes. The mathematical 4D NCAT phantom and physical cardiac phantoms were used to optimise the number of OS-EM iterations where the scatter estimate is updated and the number of MC simulated photons. The results showed that two scatter update iterations and 10(5) simulated photons are enough for the Tc-99m and Tl-201 reconstructions, whereas 10(6) simulated photons are needed to generate good quality down-scatter estimates. With these parameters, the entire Tl-201/Tc-99m dual isotope reconstruction can be accomplished in less than 3 minutes.

  12. Fast and accurate Monte Carlo-based system response modeling for a digital whole-body PET

    Science.gov (United States)

    Sun, Xiangyu; Li, Yanzhao; Yang, Lingli; Wang, Shuai; Zhang, Bo; Xiao, Peng; Xie, Qingguo

    2017-03-01

    Recently, we have developed a digital whole-body PET scanner based on multi-voltage threshold (MVT) digitizers. To mitigate the impact of resolution degrading factors, an accurate system response is calculated by Monte Carlo simulation, which is computationally expensive. To address the problem, here we improve the method of using symmetries by simulating an axial wedge region. This approach takes full advantage of intrinsic symmetries in the cylindrical PET system without significantly increasing the computation cost in the process of symmetries. A total of 4224 symmetries are exploited. It took 17 days to generate the system maxtrix on 160 cores of Xeon 2.5 GHz. Both simulation and experimental data are used to evaluate the accuracy of system response modeling. The simulation studies show the full-width-half-maximum of a line source being 2.1 mm and 3.8 mm at the center of FOV and 200 mm at the center of FOV. Experimental results show the 2.4 mm rods in the Derenzo phantom image, which can be well distinguished.

  13. Monte Carlo-based quantitative structure-activity relationship models for toxicity of organic chemicals to Daphnia magna.

    Science.gov (United States)

    Toropova, Alla P; Toropov, Andrey A; Veselinović, Aleksandar M; Veselinović, Jovana B; Leszczynska, Danuta; Leszczynski, Jerzy

    2016-11-01

    Quantitative structure-activity relationships (QSARs) for toxicity of a large set of 758 organic compounds to Daphnia magna were built up. The simplified molecular input-line entry system (SMILES) was used to represent the molecular structure. The Correlation and Logic (CORAL) software was utilized as a tool to develop the QSAR models. These models are built up using the Monte Carlo method and according to the principle "QSAR is a random event" if one checks a group of random distributions in the visible training set and the invisible validation set. Three distributions of the data into the visible training, calibration, and invisible validation sets are examined. The predictive potentials (i.e., statistical characteristics for the invisible validation set of the best model) are as follows: n = 87, r(2)  = 0.8377, root mean square error = 0.564. The mechanistic interpretations and the domain of applicability of built models are suggested and discussed. Environ Toxicol Chem 2016;35:2691-2697. © 2016 SETAC. © 2016 SETAC.

  14. Prediction in the face of uncertainty: a Monte Carlo-based approach for systems biology of cancer treatment.

    Science.gov (United States)

    Wierling, Christoph; Kühn, Alexander; Hache, Hendrik; Daskalaki, Andriani; Maschke-Dutz, Elisabeth; Peycheva, Svetlana; Li, Jian; Herwig, Ralf; Lehrach, Hans

    2012-08-15

    Cancer is known to be a complex disease and its therapy is difficult. Much information is available on molecules and pathways involved in cancer onset and progression and this data provides a valuable resource for the development of predictive computer models that can help to identify new potential drug targets or to improve therapies. Modeling cancer treatment has to take into account many cellular pathways usually leading to the construction of large mathematical models. The development of such models is complicated by the fact that relevant parameters are either completely unknown, or can at best be measured under highly artificial conditions. Here we propose an approach for constructing predictive models of such complex biological networks in the absence of accurate knowledge on parameter values, and apply this strategy to predict the effects of perturbations induced by anti-cancer drug target inhibitions on an epidermal growth factor (EGF) signaling network. The strategy is based on a Monte Carlo approach, in which the kinetic parameters are repeatedly sampled from specific probability distributions and used for multiple parallel simulations. Simulation results from different forms of the model (e.g., a model that expresses a certain mutation or mutation pattern or the treatment by a certain drug or drug combination) can be compared with the unperturbed control model and used for the prediction of the perturbation effects. This framework opens the way to experiment with complex biological networks in the computer, likely to save costs in drug development and to improve patient therapy.

  15. Fire-Retardant Polymeric Additives

    Science.gov (United States)

    Williams, Martha K.; Smith, Trent M.

    2011-01-01

    Polyhydroxyamide (PHA) and polymethoxyamide (PMeOA) are fire-retardant (FR) thermoplastic polymers and have been found to be useful as an additive for imparting fire retardant properties to other compatible, thermoplastic polymers (including some elastomers). Examples of compatible flammable polymers include nylons, polyesters, and acrylics. Unlike most prior additives, PHA and PMeOA do not appreciably degrade the mechanical properties of the matrix polymer; indeed, in some cases, mechanical properties are enhanced. Also, unlike some prior additives, PHA and PMeOA do not decompose into large amounts of corrosive or toxic compounds during combustion and can be processed at elevated temperatures. PMeOA derivative formulations were synthesized and used as an FR additive in the fabrication of polyamide (PA) and polystyrene (PS) composites with notable reduction (>30 percent for PS) in peak heat release rates compared to the neat polymer as measured by a Cone Calorimeter (ASTM E1354). Synergistic effects were noted with nanosilica composites. These nanosilica composites had more than 50-percent reduction in peak heat release rates. In a typical application, a flammable thermoplastic, thermoplastic blend, or elastomer that one seeks to render flame-retardant is first dry-mixed with PHA or PMeOA or derivative thereof. The proportion of PHA or PMeOA or derivative in the mixture is typically chosen to lie between 1 and 20 weight percent. The dry blend can then be melt-extruded. The extruded polymer blend can further be extruded and/or molded into fibers, pipes, or any other of a variety of objects that may be required to be fire-retardant. The physical and chemical mechanisms which impart flame retardancy of the additive include inhibiting free-radical oxidation in the vapor phase, preventing vaporization of fuel (the polymer), and cooling through the formation of chemical bonds in either the vapor or the condensed phase. Under thermal stress, the cyclic hydroxyl/ methoxy

  16. Litter-Spinning Retarders

    Science.gov (United States)

    Wilson, John C.

    1995-01-01

    Aerodynamic plates stop litter from spinning during hoisting by helicopter. Features of proposed litter-spinning retarders include convenience of deployment and independence from ground restraint. Retarder plate(s) folded flat against bottom of litter during storage or while litter is loaded. Plate(s) held in storage position by latch that releases manually or automatically as litter is hoisted. Upon release, springs move plates into deployed position.

  17. Genetics of mental retardation

    OpenAIRE

    Ahuja A; Thapar Anita; Owen M

    2005-01-01

    Mental retardation can follow any of the biological, environmental and psychological events that are capable of producing deficits in cognitive functions. Recent advances in molecular genetic techniques have enabled us to understand more about the molecular basis of several genetic syndromes associated with mental retardation. In contrast, where there is no discrete cause, the interplay of genetic and environmental influences remains poorly understood. This article presents a critical review ...

  18. TG-FTIR characterization of flame retardant polyurethane foams materials

    Science.gov (United States)

    Liu, W.; Tang, Y.; Li, F.; Ge, X. G.; Zhang, Z. J.

    2016-07-01

    Dimethyl methylphosphonate (DMMP) and trichloroethyl phosphtate (TCEP) have been used to enhance the flame retardancy of polyurethane foams materials (PUF). Flame retardancy and thermal degradation of PUF samples have been investigated by the LOI tests and thermal analysis. The results indicate that the excellent flame retardancy can be achieved due to the presence of the flame retardant system containing DMMP and TCEP. TG-FTIR reveals that the addition of DMMP/TCEP can not only improve the thermal stability of PUF samples but can also affect the gaseous phase at high temperature.

  19. Polarization characterization of liquid-crystal variable retarders

    Science.gov (United States)

    Montes, Iván.; Bruce, Neil C.; López-Téllez, Juan M.

    2016-08-01

    A comparison between two experimental techniques to characterize retardance as a function of applied voltage of liquid crystal variable retarders (LCVR) is presented. In the first method the variable retarder was rotated between two polarizers with their transmission axes parallel, and the retardance was calculated from the Fourier series coefficients for each applied voltage. The second method involved using two polarizers with their transmission axes perpendicular to each other, the variable retarder was placed between the polarizers with its optical axis at 45° from the horizontal, and a final stage known as "phase unwrapping" is used on experimental data to obtain the voltage-retardance function. With these two experimental methods, the voltage-retardance relationship was obtained. To verify the accuracy of this characterization a second experiment involving the production of specific polarization states was performed as the basis of a Mueller polarimeter. A method based on measuring the optical signal resulting from the application of a predetermined set of fixed values of retardance in each retarder was used. 16 elements of the Mueller matrix of a polarizer with its transmission axis at 0° and 90° were measured, and the results are compared to the expected theoretical values.

  20. Flame retardancy and its mechanism of polymers flame retarded by DBDPE/Sb2O3

    Institute of Scientific and Technical Information of China (English)

    ZUO Jian-dong; LI Rong-xun; FENG Shao-hua; LIU Guang-ye; ZHAO Jian-qing

    2008-01-01

    The flammability characterization and thermal composition of polymers flame retarded by decabromodiphenylethane(DBDPE) and antimony trioxide (Sb2O3) were studied by cone calorimeter and thermogravimetry (TG). The results show thatABS/DBDPE/Sb2O3 has the similar flammability parameters and thermal composition curves to ABS/DBDPO/Sb3O3. It suggests thatDBDPE/Sb2O3 has the similar flame retardant behavior to DBDPO/Sb2O3. The heat release rate (HRR) and the effect heat combustion (EHC) curves of polymers flame retarded by DBDPE/Sb2O3 all decrease, but the mass loss rate (MLR) curve slightly increase. It shows that the decrease of HRR is not due to the increase of char formation ratio but the generation of incombustible gases. The major flame retardant mechanism of DBDPE/Sb2O3 is gas phase flame retardant mechanism. Increasing content of Sb2O3in DBDPE/Sb2O3 can improve the flame retardant property and thermal stability of aerylonitrile butadiene styrene. Sb203 has a good synergistic effect with DBDPE.

  1. Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO4/FePO4 electrode

    Directory of Open Access Journals (Sweden)

    Kazuya Tokuda

    2014-07-01

    Full Text Available LiFePO4 is a potential positive electrode material for lithium ion batteries. We have experimentally observed an imbalance between the valence change of Fe ions and the structure change from the LiFePO4 phase to the FePO4 phase during delithiation by simultaneous in situ XRD and XANES measurements in an LiFePO4/FePO4 electrode. The ratio of structure change to valence change clearly indicates that the phase separation from LiFePO4 to FePO4 is suppressed at the beginning of delithiation, while it is accelerated at the latter stage, which is due to the coherent strain caused by the lattice misfit between the two phases.

  2. Flame Retardant Polyamide Fibres: The Challenge of Minimising Flame Retardant Additive Contents with Added Nanoclays

    Directory of Open Access Journals (Sweden)

    Richard Horrocks

    2016-08-01

    Full Text Available This work shows that halogen-free, flame retarded polyamide 6 (PA6, fabrics may be produced in which component fibres still have acceptable tensile properties and low levels (preferably ≤10 wt % of additives by incorporating a nanoclay along with two types of flame retardant formulations. The latter include (i aluminium diethyl phosphinate (AlPi at 10 wt %, known to work principally in the vapour phase and (ii ammonium sulphamate (AS/dipentaerythritol (DP system present at 2.5 and 1 wt % respectively, believed to be condense phase active. The nanoclay chosen is an organically modified montmorillonite clay, Cloisite 25A. The effect of each additive system is analysed in terms of its ability to maximise both filament tensile properties relative to 100% PA6 and flame retardant behaviour of knitted fabrics in a vertical orientation. None of the AlPi-containing formulations achieved self-extinguishability, although the presence of nanoclay promoted lower burning and melt dripping rates. The AS/DP-containing formulations with total flame retardant levels of 5.5 wt % or less showed far superior properties and with nanoclay, showed fabric extinction times ≤ 39 s and reduced melt dripping. The tensile and flammability results, supported by thermogravimetric analysis, have been interpreted in terms of the mechanism of action of each flame retardant/nanoclay type.

  3. Flame Retardant Epoxy Resins

    Science.gov (United States)

    Thompson, C. M.; Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Lyon, R. E.

    2004-01-01

    As part of a program to develop fire resistant exterior composite structures for future subsonic commercial aircraft, flame retardant epoxy resins are under investigation. Epoxies and their curing agents (aromatic diamines) containing phosphorus were synthesized and used to prepare epoxy formulations. Phosphorus was incorporated within the backbone of the epoxy resin and not used as an additive. The resulting cured epoxies were characterized by thermogravimetric analysis, propane torch test, elemental analysis and microscale combustion calorimetry. Several formulations showed excellent flame retardation with phosphorous contents as low as 1.5% by weight. The fracture toughness of plaques of several cured formulations was determined on single-edge notched bend specimens. The chemistry and properties of these new epoxy formulations are discussed.

  4. Fire-retardant foams

    Science.gov (United States)

    Gagliani, J.

    1978-01-01

    Family of polyimide resins are being developed as foams with exceptional fire-retardant properties. Foams are potentially useful for seat cushions in aircraft and ground vehicles and for applications such as home furnishings and building-construction materials. Basic formulations can be modified with reinforcing fibers or fillers to produce celular materials for variety of applications. By selecting reactants, polymer structure can be modified to give foams with properties ranging from high resiliency and flexibility to brittleness and rigidity.

  5. Retardo mental Mental retardation

    Directory of Open Access Journals (Sweden)

    Marcio M. Vasconcelos

    2004-04-01

    Full Text Available OBJETIVO: Esta revisão aborda as recentes descobertas da neurobiologia do retardo mental, enfatizando os novos recursos da citogenética, das técnicas moleculares e da neurorradiologia para esclarecer o diagnóstico. FONTES DE DADOS: O autor pesquisou o banco de dados MEDLINE da National Library of Medicine utilizando as palavras-chave "mental retardation", "developmental disability", "child" e "adolescent" em diferentes combinações, abrangendo o período de janeiro de 2000 a outubro de 2003. Também foram utilizados os bancos de dados das revistas científicas Pediatrics e New England Journal of Medicine através da palavra-chave "mental retardation". No total, o autor consultou cerca de 1.500 títulos de artigos e 500 resumos, e teve acesso direto a 150 artigos completos pertinentes. Quando oportuno, algumas referências dos artigos consultados também foram consideradas. O site Online Mendelian Inheritance in Man foi utilizado como fonte de informações em genética clínica. SÍNTESE DOS DADOS: Em outubro de 2003, o total de síndromes genéticas associadas a retardo mental chegou a 1.149. Considerando-se o conjunto das causas genéticas ou ambientais e congênitas ou adquiridas de retardo mental, a avaliação diagnóstica atual é capaz de esclarecer a etiologia em 50 a 70% dos casos. CONCLUSÕES: O autor sugere uma avaliação diagnóstica do retardo mental em etapas lógicas, visando ao uso racional dos dispendiosos recursos da citogenética, biologia molecular e neuroimagem.OBJECTIVE: This paper describes recent advances in the neurobiology of mental retardation, emphasizing new diagnostic resources provided by cytogenetics, molecular testing, and neuroimaging. SOURCES OF DATA: MEDLINE (January 2000 through October 2003, using the following key words: mental retardation, developmental disability, child, and adolescent. Search of the Pediatrics and New England Journal of Medicine websites using the key word mental retardation. The

  6. A near-infrared zero-order achromatic retarder

    Indian Academy of Sciences (India)

    Arijit Saha; Kallol Bhattacharya; Ajoy Kumar Chakraborty

    2011-10-01

    Phase retarders normally show strong wavelength dependence. Achromatic retarders which exhibit nearly identical characteristics over a wide wavelength spectrum is used in polychromatic light. The present investigation deals with a technique to design and study the characteristics of an achromatic combination of birefringent plates in 800–2000 nm range. The retarder has been designed using calcite, crystalline quartz and ADP. The thicknesses of the plates are 19.38 m, 446.14 m and 12.57 m respectively. The new arrangement of three birefringent plates proposed has the promise of producing a zero-order quarter wave achromatic combination with fairly good accuracy.

  7. Research Progress in Flame Retardants for Polypropylene%聚丙烯用阻燃剂的研究进展

    Institute of Scientific and Technical Information of China (English)

    曾伟立

    2011-01-01

    综述了聚丙烯用阻燃剂的3种阻燃作用机理,包括气相阻燃、凝聚相阻燃、中断热交换阻燃机理。重点介绍了聚丙烯用阻燃剂的研究开发进展,包括水合金属化合物阻燃剂、磷系阻燃剂、膨胀型阻燃剂、硅系阻燃剂、纳米阻燃剂等。最后,指出纳米无机阻燃剂、膨胀型阻燃剂以及具有高效阻燃、低烟、无毒的复配阻燃剂是聚丙烯崩阻燃剂未来的发展趋势。%The action mechanisms of flame retardants for polypropylene were reviewed, including gas phase flame retardancy, condensed phase flame retardancy, and interruptingheat exchange flame retardancy. The research and development status of some flame retardants for polypropylene such as hydrated metal compound flame retardants, phosphated flame retardants, intumescent flame retardants, silicone flame retardants, and nanometer flame retardants were introduced. It was pointed out that the development directions of flame retardants for polypropylene were nanometer inorganic flame retardants, intumescent flame retardants, and compound flame retardants with high-efficiency, low-smoke and non-toxicity.

  8. Optical inspection of liquid crystal variable retarder inhomogeneities.

    Science.gov (United States)

    Vargas, Javier; Uribe-Patarroyo, Néstor; Antonio Quiroga, Juan; Alvarez-Herrero, Alberto; Belenguer, Tomás

    2010-02-01

    Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardance between two orthogonal components of incident polarized light or to introduce a known phase shifting (PS) between coherent waves, both by means of an applied voltage. Typically, the retardance or PS introduced by an LCVR is not homogeneous across the aperture. On the one hand, the LCVR glass substrates present a global bend that causes an overall variation of the retardance or PS. On the other hand, in the manufacturing process of an LCVR, there sometimes appears a set of micro-air bubbles that causes local retardance or PS inhomogeneities. In this work, we present an interferometric technique based on a Mach-Zehnder interferometer that is insensitive to vibrations and capable of inspecting and characterizing the LCVR's retardance or PS inhomogeneities. The feasibility of the proposed method is demonstrated in the experimental results, where the LCVR retardance is measured with an error of about 0.2 rad. The thickness of possible micro-air bubbles is obtained with a resolution of about 50 nm.

  9. Hypoparathyroidism-retardation-dysmorphism syndrome

    Directory of Open Access Journals (Sweden)

    Kalenahalli Jagadish Kumar

    2013-01-01

    Full Text Available Congenital hypoparathyroidism, growth retardation and facial dysmorphism is a rare autosomal recessive disorder seen among children born to consanguineous couple of Arab ethnicity. This syndrome is commonly known as Sanjad-Sakati or hypoparathyroidism-retardation-dysmorphism syndrome (HRD. We report 13-year-old Hindu boy with hypoparathyroidism, tetany, facial dysmorphism and developmental delay, compatible with HRD syndrome.

  10. X-linked mental retardation.

    NARCIS (Netherlands)

    Ropers, H.H.; Hamel, B.C.J.

    2005-01-01

    Genetic factors have an important role in the aetiology of mental retardation. However, their contribution is often underestimated because in developed countries, severely affected patients are mainly sporadic cases and familial cases are rare. X-chromosomal mental retardation is the exception to

  11. Phosphorus-based Flame Retardancy Mechanisms—Old Hat or a Starting Point for Future Development?

    Directory of Open Access Journals (Sweden)

    Bernhard Schartel

    2010-09-01

    Full Text Available Different kinds of additive and reactive flame retardants containing phosphorus are increasingly successful as halogen-free alternatives for various polymeric materials and applications. Phosphorus can act in the condensed phase by enhancing charring, yielding intumescence, or through inorganic glass formation; and in the gas phase through flame inhibition. Occurrence and efficiency depend, not only on the flame retardant itself, but also on its interaction with pyrolysing polymeric material and additives. Flame retardancy is sensitive to modification of the flame retardant, the use of synergists/adjuvants, and changes to the polymeric material. A detailed understanding facilitates the launch of tailored and targeted development.

  12. Engineering Flame Retardant Biodegradable Nanocomposites

    Science.gov (United States)

    He, Shan; Yang, Kai; Guo, Yichen; Zhang, Linxi; Pack, Seongchan; Davis, Rachel; Lewin, Menahem; Ade, Harald; Korach, Chad; Kashiwagi, Takashi; Rafailovich, Miriam

    2013-03-01

    Cellulose-based PLA/PBAT polymer blends can potentially be a promising class of biodegradable nanocomposites. Adding cellulose fiber reinforcement can improve mechanical properties of biodegradable plastics, but homogeneously dispersing hydrophilic cellulose in the hydrophobic polymer matrix poses a significant challenge. We here show that resorcinol diphenyl phosphates (RDP) can be used to modify the surface energy, not only reducing phase separation between two polymer kinds but also allowing the cellulose particles and the Halloysite clay to be easily dispersed within polymer matrices to achieve synergy effect using melt blending. Here in this study we describe the use of cellulose fiber and Halloysite clay, coated with RDP surfactant, in producing the flame retardant polymer blends of PBAT(Ecoflex) and PLA which can pass the stringent UL-94 V0 test. We also utilized FTIR, SEM and AFM nanoindentation to elucidate the role RDP plays in improving the compatibility of biodegradable polymers, and to determine structure property of chars that resulted in composites that could have optimized mechanical and thermal properties. Supported by Garcia Polymer Center and NSF Foundation.

  13. Epigenetic mechanisms of mental retardation.

    Science.gov (United States)

    Schaefer, Anne; Tarakhovsky, Alexander; Greengard, Paul

    2011-01-01

    Mental retardation is a common form of cognitive impairment affecting approximately 3% of the population in industrialized countries. The mental retardation syndrome incorporates a highly diverse group of mental disorders characterized by the combination of cognitive impairment and defective adaptive behavior. The genetic basis of the disease is strongly supported by identification of the genetic lesions associated with impaired cognition, learning, and social adaptation in many mental retardation syndromes. Several of the impaired genes encode epigenetic regulators of gene expression. These regulators exert their function through genome-wide posttranslational modification of histones or by mediating and/or recognizing DNA methylation. In this chapter, we review the most recent advances in the field of epigenetic mechanisms of mental retardation. In particular, we focus on animal models of the human diseases and the mechanism of transcriptional deregulation associated with changes in the cell epigenome.

  14. Recurrence risks in mental retardation.

    OpenAIRE

    Crow, Y J; Tolmie, J L

    1998-01-01

    Despite improvements in diagnostic techniques and progress made in mapping genes associated with syndromal mental handicap, the estimation of recurrence risks in non-syndromal mental retardation is still dependent on empirical data. Unfortunately, few studies are available to guide the clinician and their results differ significantly. For example, recurrence risks to all sibs of a male index patient with severe mental retardation vary between 3.5% and 14% in commonly quoted series. The presen...

  15. Balanced translocations in mental retardation.

    Science.gov (United States)

    Vandeweyer, Geert; Kooy, R Frank

    2009-07-01

    Over the past few decades, the knowledge on genetic defects causing mental retardation has dramatically increased. In this review, we discuss the importance of balanced chromosomal translocations in the identification of genes responsible for mental retardation. We present a database-search guided overview of balanced translocations identified in patients with mental retardation. We divide those in four categories: (1) balanced translocations that helped to identify a causative gene within a contiguous gene syndrome, (2) balanced translocations that led to the identification of a mental retardation gene confirmed by independent methods, (3) balanced translocations disrupting candidate genes that have not been confirmed by independent methods and (4) balanced translocations not reported to disrupt protein coding sequences. It can safely be concluded that balanced translocations have been instrumental in the identification of multiple genes that are involved in mental retardation. In addition, many more candidate genes were identified with a suspected but (as yet?) unconfirmed role in mental retardation. Some balanced translocations do not disrupt a protein coding gene and it can be speculated that in the light of recent findings concerning ncRNA's and ultra-conserved regions, such findings are worth further investigation as these potentially may lead us to the discovery of novel disease mechanisms.

  16. Experimental studies on a single-stage compressor equipped with profiles with controlled retardation. Phase 2. Final report; Experimentelle Untersuchungen an einem einstufigen Verdichter mit Profilen mit kontrollierter Verzoegerung. Phase 2. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Blaha, C.; Schulze, G.

    1996-04-01

    As part of the TurboTech study detailed measurements were performed on compressor cascades, single-stage machines, and whole compressors. The purpose of this was to gain greater clarity concerning flow conditions in compressors. The experimental results obtained were to permit a refinement of the calculation methods thus creating a reliable tool for dimensioning the HTGT compressors. The project described here is dedicated to the single stage. The tasks of phase II can be divided as follows: determination of the performance map; numerical simulation of operating behaviour; dimensioning check; analysis of the simulation and measurements and their comparison; and further measurements for the study of special flow phenomena and development of an experimental - data base for the validation of calculation methods. (orig./GL) [Deutsch] Im Rahmen von TurboTech werden detaillierte Messungen an Verdichtergittern, einstufigen Maschinen und Gesamtverdichtern durchgefuehrt, um groessere Klarheit ueber die Stroemungsverhaeltnisse in Verdichtern zu erlangen. Hierbei sollen mit Hilfe der Versuchsergebnisse die Rechenverfahren verfeinert werden, um so ein zuverlaessiges Werkzeug zur Auslegung des HTGT Verdichters in die Hand zu bekommen. Das beschriebene Vorhaben ist der Einzelstufe gewidmet. Die Aufgaben der Phase II unterteilten sich in folgende Punkte: - Vermessung des Kennfeldes - Numerische Simulation des Betriebsverhaltens - Ueberpruefung der Auslegung - Analyse der Simulation und der Messungen sowie deren Vergleich - Durchfuehrung weiterer Messungen zur Untersuchung spezieller Stroemungsphaenomene und Schaffung einer Basis experimenteller Daten zur Validierung von Rechenverfahren. (orig./GL)

  17. Development of novel fire retardants

    Science.gov (United States)

    Sigdel Regmi, Bhawani

    Numerous candidate environmentally-friendly, water-soluble, and non-toxic fire retardants and fire-retarding processes were developed and tested according to the ASTM D 3801 flammability test and the NRL 8093 smoldering test. Flame retardants that passed the ASTM D 3801 flammability test with the highest V0 rating were boron esters of guanidinium hydroxycarboxylate (glycolate, salicylate and dihydroxybenzoate), zinc gluconate borate ester, and cyanoacetate salts of organic bases (melaminium, cyanoguanidinium, and ammonium). Several related compounds pass this test with the lower V1 rating. Two new synergistic flame and smolder retarding systems were developed in which the individual components were incapable of preventing flame spread or smoldering but in combination they were highly effective. These systems were mixtures of either guanyl urea phosphate and boric acid or beta-alanine and boric acid. Compositions leading to the maximum solubility of boron oxides in the ammonium borate/sodium borate system were determined at several temperatures and the formation of mixtures exceeding 50% dissolved boric acid equivalents was found possible. These mixtures were applied as flame retardants for wood, paper, and carbon-loaded polyurethane foam both directly and indirectly by in situ precipitation of boric acid or zinc borate by appropriate chemical treatments. These all passed the ASTM flammability test with V0 rating. The performance of the boron-containing fire retardants is likely due to deposition of protective boron oxide coatings at elevated temperatures except where phosphate was present and a protective boron phosphate was deposited instead. In all cases, the oxidation of carbonaceous char was strongly inhibited. The hydroxycarboxylate groups generally formed intumescent chars during thermal decomposition that also contributed to fire retardancy.

  18. Highly accurate spectral retardance characterization of a liquid crystal retarder including Fabry-Perot interference effects

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Asticio [Departamento de Ciencias Físicas, Universidad de La Frontera, Temuco (Chile); Center for Optics and Photonics, Universidad de Concepción, Casilla 4016, Concepción (Chile); Mar Sánchez-López, María del [Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche (Spain); García-Martínez, Pascuala [Departament d' Òptica, Universitat de València, 45100 Burjassot (Spain); Arias, Julia; Moreno, Ignacio [Departamento de Ciencia de Materiales, Óptica y Tecnología Electrónica, Universidad Miguel Hernández, 03202 Elche (Spain)

    2014-01-21

    Multiple-beam Fabry-Perot (FP) interferences occur in liquid crystal retarders (LCR) devoid of an antireflective coating. In this work, a highly accurate method to obtain the spectral retardance of such devices is presented. On the basis of a simple model of the LCR that includes FP effects and by using a voltage transfer function, we show how the FP features in the transmission spectrum can be used to accurately retrieve the ordinary and extraordinary spectral phase delays, and the voltage dependence of the latter. As a consequence, the modulation characteristics of the device are fully determined with high accuracy by means of a few off-state physical parameters which are wavelength-dependent, and a single voltage transfer function that is valid within the spectral range of characterization.

  19. Firefighters and flame retardant activism.

    Science.gov (United States)

    Cordner, Alissa; Rodgers, Kathryn M; Brown, Phil; Morello-Frosch, Rachel

    2015-02-01

    In the past decade, exposure to flame retardant chemicals has become a pressing health concern and widely discussed topic of public safety for firefighters in the United States. Working through local, state, and national unions and independent health and advocacy organizations, firefighters have made important contributions to efforts to restrict the use of certain flame retardants. Firefighters are key members in advocacy coalitions dedicated to developing new environmental health regulations and reforming flammability standards to reflect the best available fire science. Their involvement has been motivated by substantiated health concerns and critiques of deceptive lobbying practices by the chemical industry. Drawing on observations and interviews with firefighters, fire safety experts, and other involved stakeholders, this article describes why firefighters are increasingly concerned about their exposure to flame retardant chemicals in consumer products, and analyzes their involvement in state and national environmental health coalitions.

  20. Auto cannibalism in mental retardation

    Directory of Open Access Journals (Sweden)

    Rohit Verma

    2014-01-01

    Full Text Available Mental retardation (MR deems an individual more vulnerable to psychopathologies. The individual may develop an array of behavioral disturbances manifesting themselves in the form of aggressive and destructive conduct, violent fits of anger, stereotyped, or self-injuring behavior. Self-injurious behavior is heterogeneous in nature ranging from mild to severe variant. We report a case of a 7-year-old boy with MR with self-inflicted severe oral injuries of cannibalistic nature presenting as cleft lip and palate. A more extensive research is needed on the problem behaviors in mentally retarded patients for early detection and effective and timely intervention leading to a better outcome.

  1. Auto cannibalism in mental retardation.

    Science.gov (United States)

    Verma, Rohit; Mina, Shaily; Sachdeva, Ankur

    2014-01-01

    Mental retardation (MR) deems an individual more vulnerable to psychopathologies. The individual may develop an array of behavioral disturbances manifesting themselves in the form of aggressive and destructive conduct, violent fits of anger, stereotyped, or self-injuring behavior. Self-injurious behavior is heterogeneous in nature ranging from mild to severe variant. We report a case of a 7-year-old boy with MR with self-inflicted severe oral injuries of cannibalistic nature presenting as cleft lip and palate. A more extensive research is needed on the problem behaviors in mentally retarded patients for early detection and effective and timely intervention leading to a better outcome.

  2. The Influence of Flame Retardant Treated Timber Density on Combustibility

    Directory of Open Access Journals (Sweden)

    Zbignev Karpovič

    2011-04-01

    Full Text Available Timber is widely used as a construction material in the majority of countries. In most cases, timber is the main structural material. Timber and timber fabrics used in building structure elements have to fulfill the requirements of fire safety. This article presents factors affecting the combustibility of timber, mainly the influence of flame retardants on the combustion phase, timber density and moisture. The influence of flame retardant treated timber density on combustibility is analyzed in this paper. Research was performed according to the requirements of the standard LST ISO 5657:1999 “Reaction to fire tests – ignitibility of building products using a radiant heat source”. The influence of flame retardant treated timber density on combustibility is assessed according to duration up to the combustion of the specimen. Article in Lithuanian

  3. Acute and Developmental Behavioral Effects of Flame Retardants and Related Chemicals in Zebrafish

    Science.gov (United States)

    As polybrominated diphenyl ethers are phased out, numerous compounds are emerging as potential replacement flame retardants for use in consumer and electronic products. Little is known, however, about the neurobehavioral toxicity of these replacements. This study evaluated the ne...

  4. Acute Neurobehavorial Toxicity of Flame Retardant Replacement Compounds in Zebrafish Larvae

    Science.gov (United States)

    As polybrominated diphenyl ethers (PBDEs) are phased out, numerous compounds areemerging as potential replacement flame retardants for use in consumer and electronicproducts. Little is known, however, about the neurobehavioral toxicity of thesereplacements. This study evaluated t...

  5. Research on flame retardation of wool fibers

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Ichiro; Ametani, Kazuo; Sawai, Takeshi (Tokyo Metropolitan Isotope Research Center (Japan))

    1990-01-01

    Flame retardant, vinyl phosphonate oligomer, was uniformly impregnated in wool fibers, and by irradiating low energy electron beam or cobalt-60 gamma ray, the flame retardation of fabrics was attempted, as the results, the following knowledges were obtained. At the rate of sticking of flame retardant lower than that in cotton fabrics, sufficient flame retarding property can be given. The flame retarding property withstands 30 times of washing. The lowering of strength due to the processing hardly arose. For the flame retardation, gamma-ray was more effective than electron beam. Since the accidents of burning clothes have occurred frequently, their flame retardation has been demanded. So far the flame retardation of cotton fabrics has been advanced, but this time the research on the flame retardation of wool fabrics was carried out by the same method. The experimental method is explained. As for the performance of the processed fabrics, the rate of sticking of the flame retardant, the efficiency of utilization, the flame retarding property, the endurance in washing and the tensile and tearing strength were examined. As the oxygen index was higher, the flame retarding property was higher, and in the case of the index being more than 27, the flame retarding property is sufficient, that is, the rate of sticking of 6% in serge and 5% in muslin. (K.I.).

  6. Detection of Malingered Mental Retardation

    Science.gov (United States)

    Shandera, Anne L.; Berry, David T. R.; Clark, Jessica A.; Schipper, Lindsey J.; Graue, Lili O.; Harp, Jordan P.

    2010-01-01

    In a cross-validation of results from L. O. Graue et al. (2007), standard psychological assessment instruments, as well as tests of neurocognitive and psychiatric feigning, were administered under standard instructions to 24 participants diagnosed with mild mental retardation (MR) and 10 demographically matched community volunteers (CVH). A 2nd…

  7. Idiots Savants: Retarded and Gifted.

    Science.gov (United States)

    Yewchuk, Carolyn

    The paper reviews the paradoxical nature of idiots savants, persons who, although retarded, have exceptional skills in certain areas. Various explanations for the phenomenon are discussed, such as a specific genetic endowment, a specialized compensatory response to general intellectual deficiency, and possession of an eidetic memory. Various…

  8. Flame Retardants Used in Flexible Polyurethane Foam

    Science.gov (United States)

    The partnership project on flame retardants in furniture seeks to update the health and environmental profiles of flame-retardant chemicals that meet fire safety standards for upholstered consumer products with polyurethane foam

  9. Mental Retardation and Parenting Stress

    Directory of Open Access Journals (Sweden)

    Eleni Siamaga

    2011-01-01

    Full Text Available Backround: The presence, upbringing and looking after of a mentally retarded child in the family, can become a threat to the mental health of its parents and is the main predisposing factor of stress for the parents.Aim: The purpose of this systematic review is (a to document the contemporary research bibliography related to the stress of parents with mentally retarded children, (b to aggregate the factors and secondary parameters based on the contemporary research related to the influence of the (child’s mental retardation on the parents and (c to show an intercultural aspect regarding the presence of stress to parents with mentally retarded children.Methods: Systematic review of research articles published in scientific journals included in the international academic databases HEAL-LING, SAGE, ELSEVIER, WILSON, SCIENCEDIRECT, MEDLINE, PUBMED, PsycINFO, Cochrane, EMBASE, SCIRUS and CINAHL having as search criteria and key words the terms («parental stress and mental retardation» [MeSH], «parenting stress and persons with special needs» [MeSH], «mental retardation and family problems» [MeSH], «stress and parents» [MeSH], «parenting and stress» [MeSH], «mental delay and parents» [MeSH], «developmental disabilities and family stress» [MeSH], «intellectual handicap and parenting» [MeSH], «maternal stress and child with disabilities» [MeSH].Discussion: The review has proven that all forms of mental retardation have an important -from a statistic point of viewimpacton the parents’ mental health. Anxiety, stress and depression are common symptoms mentioned by the parents.Additionally, there are individual variables such as the husband-wife relationship, the parents’ approach to their child’s disability, the parental strategies used in order to cope with the daily life of the child’s disability and the behavioural problems of their child, all of which contribute to the increase of the level of parental stress

  10. Reducing radiation dose to selected organs by selecting the tube start angle in MDCT helical scans: A Monte Carlo based study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Di; Zankl, Maria; DeMarco, John J.; Cagnon, Chris H.; Angel, Erin; Turner, Adam C.; McNitt-Gray, Michael F. [David Geffen School of Medicine at UCLA, Los Angeles, California 90024 (United States); German Research Center for Environmental Health (GmbH), Institute of Radiation Protection, Helmholtz Zentrum Muenchen, Ingolstaedter Landstrasse 1, 85764 Neuherberg (Germany); David Geffen School of Medicine at UCLA, Los Angeles, California 90024 (United States)

    2009-12-15

    Purpose: Previous work has demonstrated that there are significant dose variations with a sinusoidal pattern on the peripheral of a CTDI 32 cm phantom or on the surface of an anthropomorphic phantom when helical CT scanning is performed, resulting in the creation of ''hot'' spots or ''cold'' spots. The purpose of this work was to perform preliminary investigations into the feasibility of exploiting these variations to reduce dose to selected radiosensitive organs solely by varying the tube start angle in CT scans. Methods: Radiation dose to several radiosensitive organs (including breasts, thyroid, uterus, gonads, and eye lenses) resulting from MDCT scans were estimated using Monte Carlo simulation methods on voxelized patient models, including GSF's Baby, Child, and Irene. Dose to fetus was also estimated using four pregnant female models based on CT images of the pregnant patients. Whole-body scans were simulated using 120 kVp, 300 mAs, both 28.8 and 40 mm nominal collimations, and pitch values of 1.5, 1.0, and 0.75 under a wide range of start angles (0 deg. - 340 deg. in 20 deg. increments). The relationship between tube start angle and organ dose was examined for each organ, and the potential dose reduction was calculated. Results: Some organs exhibit a strong dose variation, depending on the tube start angle. For small peripheral organs (e.g., the eye lenses of the Baby phantom at pitch 1.5 with 40 mm collimation), the minimum dose can be 41% lower than the maximum dose, depending on the tube start angle. In general, larger dose reductions occur for smaller peripheral organs in smaller patients when wider collimation is used. Pitch 1.5 and pitch 0.75 have different mechanisms of dose reduction. For pitch 1.5 scans, the dose is usually lowest when the tube start angle is such that the x-ray tube is posterior to the patient when it passes the longitudinal location of the organ. For pitch 0.75 scans, the dose is lowest when the tube start angle is such that the x-ray tube is anterior to the patient when it passes the longitudinal location of the organ. Conclusions: Helical MDCT scanning at pitch 1.5 and pitch 0.75 results in ''cold spots'' and ''hot spots'' that are created both at surface and in-depth locations within patients. For organs that have a relatively small longitudinal extent, dose can vary considerably with different start angles. While current MDCT systems do not provide the user with the ability to control the tube start angle, these results indicate that in these specific situations (pitch 1.5 or pitch 0.75, small organs and especially small patients), there could be significant dose savings to organs if that functionality would be provided.

  11. Comparison of diffusion approximation and Monte Carlo based finite element models for simulating thermal responses to laser irradiation in discrete vessels.

    Science.gov (United States)

    Zhang, Rong; Verkruysse, Wim; Aguilar, Guillermo; Nelson, J Stuart

    2005-09-07

    Both diffusion approximation (DA) and Monte Carlo (MC) models have been used to simulate light distribution in multilayered human skin with or without discrete blood vessels. However, no detailed comparison of the light distribution, heat generation and induced thermal damage between these two models has been done for discrete vessels. Three models were constructed: (1) MC-based finite element method (FEM) model, referred to as MC-FEM; (2) DA-based FEM with simple scaling factors according to chromophore concentrations (SFCC) in the epidermis and vessels, referred to as DA-FEM-SFCC; and (3) DA-FEM with improved scaling factors (ISF) obtained by equalizing the total light energy depositions that are solved from the DA and MC models in the epidermis and vessels, respectively, referred to as DA-FEM-ISF. The results show that DA-FEM-SFCC underestimates the light energy deposition in the epidermis and vessels when compared to MC-FEM. The difference is nonlinearly dependent on wavelength, dermal blood volume fraction, vessel size and depth, etc. Thus, the temperature and damage profiles are also dramatically different. DA-FEM-ISF achieves much better results in calculating heat generation and induced thermal damage when compared to MC-FEM, and has the advantages of both calculation speed and accuracy. The disadvantage is that a multidimensional ISF table is needed for DA-FEM-ISF to be a practical modelling tool.

  12. Clinically applicable Monte Carlo-based biological dose optimization for the treatment of head and neck cancers with spot-scanning proton therapy

    CERN Document Server

    Tseung, H Wan Chan; Kreofsky, C R; Ma, D; Beltran, C

    2016-01-01

    Purpose: To demonstrate the feasibility of fast Monte Carlo (MC) based inverse biological planning for the treatment of head and neck tumors in spot-scanning proton therapy. Methods: Recently, a fast and accurate Graphics Processor Unit (GPU)-based MC simulation of proton transport was developed and used as the dose calculation engine in a GPU-accelerated IMPT optimizer. Besides dose, the dose-averaged linear energy transfer (LETd) can be simultaneously scored, which makes biological dose (BD) optimization possible. To convert from LETd to BD, a linear relation was assumed. Using this novel optimizer, inverse biological planning was applied to 4 patients: 2 small and 1 large thyroid tumor targets, and 1 glioma case. To create these plans, constraints were placed to maintain the physical dose (PD) within 1.25 times the prescription while maximizing target BD. For comparison, conventional IMRT and IMPT plans were created for each case in Eclipse (Varian, Inc). The same critical structure PD constraints were use...

  13. Monte Carlo-based Spencer-Attix and Bragg-Gray tissue-to-air stopping power ratios for ISO beta sources.

    Science.gov (United States)

    Selvam, T Palani; Vandana, S; Bakshi, A K; Babu, D A R

    2016-02-01

    Spencer-Attix (SA) and Bragg-Gray (BG) mass-collision-stopping-power ratios of tissue-to-air are calculated using a modified version of EGSnrc-based SPRRZnrc user-code for the International Organization for Standardization (ISO) beta sources such as (147)Pm, (85)Kr, (90)Sr/(90)Y and (106)Ru/(106)Rh. The ratios are calculated at 5 and 70 µm depths along the central axis of the unit density ICRU-4-element tissue phantom as a function of air-cavity lengths of the extrapolation chamber l = 0.025-0.25 cm. The study shows that the BG values are independent of l and agree well with the ISO-reported values for the above sources. The overall variation in the SA values is ∼0.3% for all the investigated sources, when l is varied from 0.025 to 0.25 cm. As energy of the beta increases the SA stopping-power ratio for a given cavity length decreases. For example, SA values of (147)Pm are higher by ∼2% when compared with the corresponding values of (106)Ru/(106)Rh source. SA stopping-power ratios are higher than the BG stopping-power ratios and the degree of variation depends on type of source and the value of l. For example, the difference is up to 0.7 % at l = 0.025 cm for the (90)Sr/(90)Y source. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Hydration structure in concentrated aqueous lithium chloride solutions: A reverse Monte Carlo based combination of molecular dynamics simulations and diffraction data

    Science.gov (United States)

    Harsányi, I.; Pusztai, L.

    2012-11-01

    We report on a comparison of three interaction potential models of water (SPC/E, TIP4P-2005, and SWM4-DP) for describing the structure of concentrated aqueous lithium chloride solutions. Classical molecular dynamics simulations have been carried out and total scattering structure factors, calculated from the particle configurations, were compared with experimental diffraction data. Later, reverse Monte Carlo structural modelling was applied for refining molecular dynamics results, so that particle configurations consistent with neutron and X-ray diffraction data could be prepared that, at the same time, were as close as possible to the final stage of the molecular dynamics simulations. Partial radial distribution functions, first neighbors, and angular correlations were analysed further from the best fitting particle configurations. It was found that none of the water potential models describe the structure perfectly; overall, the SWM4-DP model seems to be the most promising. At the highest concentrations the SPC/E model appears to provide the best approximation of the water structure, whereas the TIP4P-2005 model proved to be the most successful for estimating the lithium-oxygen partial radial distribution function at each concentration.

  15. CARMEN: a system Monte Carlo based on linear programming from direct openings; CARMEN: Un sistema de planficiacion Monte Carlo basado en programacion lineal a partir de aberturas directas

    Energy Technology Data Exchange (ETDEWEB)

    Ureba, A.; Pereira-Barbeiro, A. R.; Jimenez-Ortega, E.; Baeza, J. A.; Salguero, F. J.; Leal, A.

    2013-07-01

    The use of Monte Carlo (MC) has shown an improvement in the accuracy of the calculation of the dose compared to other analytics algorithms installed on the systems of business planning, especially in the case of non-standard situations typical of complex techniques such as IMRT and VMAT. Our treatment planning system called CARMEN, is based on the complete simulation, both the beam transport in the head of the accelerator and the patient, and simulation designed for efficient operation in terms of the accuracy of the estimate and the required computation times. (Author)

  16. Comparison of interatomic potentials of water via structure factors reconstructed from simulated partial radial distribution functions: a reverse Monte Carlo based approach

    Science.gov (United States)

    Steinczinger, Zsuzsanna; Jóvári, Pál; Pusztai, László

    2017-01-01

    Neutron- and x-ray weighted total structure factors of liquid water have been calculated on the basis of the intermolecular parts of partial radial distribution functions resulting from various computer simulations. The approach includes reverse Monte Carlo (RMC) modelling of these partials, using realistic flexible molecules, and the calculation of experimental diffraction data, including the intramolecular contributions, from the RMC particle configurations. The procedure has been applied to ten sets of intermolecular partial radial distribution functions obtained from various computer simulations, including one set from an ab initio molecular dynamics, of water. It is found that modern polarizable water potentials, such as SWM4-DP and BK3 are the most successful in reproducing measured diffraction data.

  17. Inversion of Schlumberger resistivity sounding data from the critically dynamic Koyna region using the Hybrid Monte Carlo-based neural network approach

    Directory of Open Access Journals (Sweden)

    S. Maiti

    2011-03-01

    Full Text Available Koyna region is well-known for its triggered seismic activities since the hazardous earthquake of M=6.3 occurred around the Koyna reservoir on 10 December 1967. Understanding the shallow distribution of resistivity pattern in such a seismically critical area is vital for mapping faults, fractures and lineaments. However, deducing true resistivity distribution from the apparent resistivity data lacks precise information due to intrinsic non-linearity in the data structures. Here we present a new technique based on the Bayesian neural network (BNN theory using the concept of Hybrid Monte Carlo (HMC/Markov Chain Monte Carlo (MCMC simulation scheme. The new method is applied to invert one and two-dimensional Direct Current (DC vertical electrical sounding (VES data acquired around the Koyna region in India. Prior to apply the method on actual resistivity data, the new method was tested for simulating synthetic signal. In this approach the objective/cost function is optimized following the Hybrid Monte Carlo (HMC/Markov Chain Monte Carlo (MCMC sampling based algorithm and each trajectory was updated by approximating the Hamiltonian differential equations through a leapfrog discretization scheme. The stability of the new inversion technique was tested in presence of correlated red noise and uncertainty of the result was estimated using the BNN code. The estimated true resistivity distribution was compared with the results of singular value decomposition (SVD-based conventional resistivity inversion results. Comparative results based on the HMC-based Bayesian Neural Network are in good agreement with the existing model results, however in some cases, it also provides more detail and precise results, which appears to be justified with local geological and structural details. The new BNN approach based on HMC is faster and proved to be a promising inversion scheme to interpret complex and non-linear resistivity problems. The HMC-based BNN results are quite useful for the interpretation of fractures and lineaments in seismically active region.

  18. Evaluation of a commercial VMC++ Monte Carlo based treatment planning system for electron beams using EGSnrc/BEAMnrc simulations and measurements.

    Science.gov (United States)

    Edimo, P; Clermont, C; Kwato, M G; Vynckier, S

    2009-09-01

    In the present work, Monte Carlo (MC) models of electron beams (energies 4, 12 and 18MeV) from an Elekta SL25 medical linear accelerator were simulated using EGSnrc/BEAMnrc user code. The calculated dose distributions were benchmarked by comparison with measurements made in a water phantom for a wide range of open field sizes and insert combinations, at a single source-to-surface distance (SSD) of 100cm. These BEAMnrc models were used to evaluate the accuracy of a commercial MC dose calculation engine for electron beam treatment planning (Oncentra MasterPlan Treament Planning System (OMTPS) version 1.4, Nucletron) for two energies, 4 and 12MeV. Output factors were furthermore measured in the water phantom and compared to BEAMnrc and OMTPS. The overall agreement between predicted and measured output factors was comparable for both BEAMnrc and OMTPS, except for a few asymmetric and/or small insert cutouts, where larger deviations between measurements and the values predicted from BEAMnrc as well as OMTPS computations were recorded. However, in the heterogeneous phantom, differences between BEAMnrc and measurements ranged from 0.5 to 2.0% between two ribs and 0.6-1.0% below the ribs, whereas the range difference between OMTPS and measurements was the same (0.5-4.0%) in both areas. With respect to output factors, the overall agreement between BEAMnrc and measurements was usually within 1.0% whereas differences up to nearly 3.0% were observed for OMTPS. This paper focuses on a comparison for clinical cases, including the effects of electron beam attenuations in a heterogeneous phantom. It, therefore, complements previously reported data (only based on measurements) in one other paper on commissioning of the VMC++ dose calculation engine. These results demonstrate that the VMC++ algorithm is more robust in predicting dose distribution than Pencil beam based algorithms for the electron beams investigated.

  19. 基于蒙特卡罗模拟的可转换债券定价研究%Monte Carlo-based pricing of convertible bonds

    Institute of Scientific and Technical Information of China (English)

    赵洋; 赵立臣

    2009-01-01

    The paper applied the least-square Monte Carlo method proposed by Longstaff,et al.to price convertible bond,so as to solve the problem of prcing the path-dependent clauses and American option features embeded in convertible bonds.Convertible bonds are complex hybrid securities being subject to equity risk,credit risk,and interest rate risk.In the established pricing model,the assumption of constant volatility is relaxed and the volatility is estimated with GARCH (1,1),according to TF model,the credit risk is represented with the credit risk spread,and the yield curve is estimsted with Nelson-Siegel method.By empirical research,it is found that the convertible bonds in China are underpriced by 2% to 3%.%使用Longstaff等提出的最小二乘蒙特卡罗方法为可转换债券定价,从而解决为可转换债券中路径依赖条款和美式期权进行定价的难题.可转换债券是复杂的结构化产品,同时受股价风险、信用风险和利率风险影响.在建立的定价模型中,股价过程放松波动率为常数的假设,用GARCH(1,1)模型估计波动率,信用风险根据TF模型用常数信用利差代表,收益率曲线用Nelson-Siegel方法估计.通过实证检验发现国内可转换债券市场存在低估,低估幅度在2%~3%之间.

  20. Dosimetric verification and clinical evaluation of a new commercially available Monte Carlo-based dose algorithm for application in stereotactic body radiation therapy (SBRT) treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Fragoso, Margarida; Wen Ning; Kumar, Sanath; Liu Dezhi; Ryu, Samuel; Movsas, Benjamin; Munther, Ajlouni; Chetty, Indrin J, E-mail: ichetty1@hfhs.or [Henry Ford Health System, Detroit, MI (United States)

    2010-08-21

    Modern cancer treatment techniques, such as intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT), have greatly increased the demand for more accurate treatment planning (structure definition, dose calculation, etc) and dose delivery. The ability to use fast and accurate Monte Carlo (MC)-based dose calculations within a commercial treatment planning system (TPS) in the clinical setting is now becoming more of a reality. This study describes the dosimetric verification and initial clinical evaluation of a new commercial MC-based photon beam dose calculation algorithm, within the iPlan v.4.1 TPS (BrainLAB AG, Feldkirchen, Germany). Experimental verification of the MC photon beam model was performed with film and ionization chambers in water phantoms and in heterogeneous solid-water slabs containing bone and lung-equivalent materials for a 6 MV photon beam from a Novalis (BrainLAB) linear accelerator (linac) with a micro-multileaf collimator (m{sub 3} MLC). The agreement between calculated and measured dose distributions in the water phantom verification tests was, on average, within 2%/1 mm (high dose/high gradient) and was within {+-}4%/2 mm in the heterogeneous slab geometries. Example treatment plans in the lung show significant differences between the MC and one-dimensional pencil beam (PB) algorithms within iPlan, especially for small lesions in the lung, where electronic disequilibrium effects are emphasized. Other user-specific features in the iPlan system, such as options to select dose to water or dose to medium, and the mean variance level, have been investigated. Timing results for typical lung treatment plans show the total computation time (including that for processing and I/O) to be less than 10 min for 1-2% mean variance (running on a single PC with 8 Intel Xeon X5355 CPUs, 2.66 GHz). Overall, the iPlan MC algorithm is demonstrated to be an accurate and efficient dose algorithm, incorporating robust tools for MC-based SBRT treatment planning in the routine clinical setting.

  1. Experimental validation of a Monte Carlo-based kV x-ray projection model for the Varian linac-mounted cone-beam CT imaging system

    Science.gov (United States)

    Lazos, Dimitrios; Pokhrel, Damodar; Su, Zhong; Lu, Jun; Williamson, Jeffrey F.

    2008-03-01

    Fast and accurate modeling of cone-beam CT (CBCT) x-ray projection data can improve CBCT image quality either by linearizing projection data for each patient prior to image reconstruction (thereby mitigating detector blur/lag, spectral hardening, and scatter artifacts) or indirectly by supporting rigorous comparative simulation studies of competing image reconstruction and processing algorithms. In this study, we compare Monte Carlo-computed x-ray projections with projections experimentally acquired from our Varian Trilogy CBCT imaging system for phantoms of known design. Our recently developed Monte Carlo photon-transport code, PTRAN, was used to compute primary and scatter projections for cylindrical phantom of known diameter (NA model 76-410) with and without bow-tie filter and antiscatter grid for both full- and half-fan geometries. These simulations were based upon measured 120 kVp spectra, beam profiles, and flat-panel detector (4030CB) point-spread function. Compound Poisson- process noise was simulated based upon measured beam output. Computed projections were compared to flat- and dark-field corrected 4030CB images where scatter profiles were estimated by subtracting narrow axial-from full axial width 4030CB profiles. In agreement with the literature, the difference between simulated and measured projection data is of the order of 6-8%. The measurement of the scatter profiles is affected by the long tails of the detector PSF. Higher accuracy can be achieved mainly by improving the beam modeling and correcting the non linearities induced by the detector PSF.

  2. Monte Carlo-based investigations on the impact of removing the flattening filter on beam quality specifiers for photon beam dosimetry.

    Science.gov (United States)

    Czarnecki, Damian; Poppe, Björn; Zink, Klemens

    2017-06-01

    The impact of removing the flattening filter in clinical electron accelerators on the relationship between dosimetric quantities such as beam quality specifiers and the mean photon and electron energies of the photon radiation field was investigated by Monte Carlo simulations. The purpose of this work was to determine the uncertainties when using the well-known beam quality specifiers or energy-based beam specifiers as predictors of dosimetric photon field properties when removing the flattening filter. Monte Carlo simulations applying eight different linear accelerator head models with and without flattening filter were performed in order to generate realistic radiation sources and calculate field properties such as restricted mass collision stopping power ratios (L¯/ρ)airwater, mean photon and secondary electron energies. To study the impact of removing the flattening filter on the beam quality correction factors kQ , this factor for detailed ionization chamber models was calculated by Monte Carlo simulations. Stopping power ratios (L¯/ρ)airwater and kQ values for different ionization chambers as a function of TPR1020 and %dd(10)x were calculated. Moreover, mean photon energies in air and at the point of measurement in water as well as mean secondary electron energies at the point of measurement were calculated. The results revealed that removing the flattening filter led to a change within 0.3% in the relationship between %dd(10)x and (L¯/ρ)airwater, whereby the relationship between TPR1020 and (L¯/ρ)airwater changed up to 0.8% for high energy photon beams. However, TPR1020 was a good predictor of (L¯/ρ)airwater for both types of linear accelerator with energies mean photon energy below the linear accelerators head as well as at the point of measurement may not be suitable as a predictor of (L¯/ρ)airwater and kQ to merge the dosimetry of both linear accelerator types. It was possible to derive (L¯/ρ)airwater using the mean secondary electron energy at the point of measurement as a predictor with an accuracy of 0.17%. A bias between kQ for linear accelerators with and without flattening filter within 1.1% and 1.6% was observed for TPR1020 and %dd(10)x respectively. The results of this study have shown that removing the flattening filter led to a change in the relationship between the well-known beam quality specifiers and dosimetric quantities at the point of measurement, namely (L¯/ρ)airwater, mean photon and electron energy. Furthermore, the results show that a beam profile correction is important for dose measurements with large ionization chambers in flattening filter free beams. © 2017 American Association of Physicists in Medicine.

  3. Mental Retardation: Prevention Strategies That Work.

    Science.gov (United States)

    President's Committee on Mental Retardation, Washington, DC.

    The report by the President's Committee on Mental Retardation reviews the current state of knowledge in the area of biological and environmental prevention of mental retardation and describes programs on the frontiers of research or service delivery. Section I examines programs that are effectively preventing mental retardation through biomedical…

  4. MENTAL RETARDATION--THE PRESENT PROBLEM.

    Science.gov (United States)

    SHAFTER, ALBERT J.

    MENTAL RETARDATION IS DEFINED AS A MENTAL DEFECT, NOT A DISEASE. LEVELS OF SEVERITY IN MENTAL RETARDATION ARE CAUSED BY AN INTERRELATIONSHIP BETWEEN HEREDITY AND ENVIRONMENT. ONE OF THE MAJOR PROBLEMS CONCERNS THE LONGER LIFE EXPECTANCY OF THE RETARDATE DUE TO IMPROVEMENTS IN MODERN MEDICINE. THIS IS CREATING A SITUATION WHERE RESIDENTIAL…

  5. Physical properties and flame-retardant effects of polyurethane coatings containing pyrophosphoric lactone modified polyesters

    Energy Technology Data Exchange (ETDEWEB)

    Chung, D.J.; Kim, S.R.; Park, H.J.; Park, H.S. [Myongji University, Yongin (Korea); Kim, S.J. [Korea Institute of Construction Materials, Seoul (Korea)

    2002-05-01

    Pyrophosphoric lactone modified polyester(PATT) containing two phosphorous functional groups in one unit structure was synthesized to prepare a non-toxic reactive flame-retardant coatings. Then the PATT was cured at room temperature with isocyanate, toluene diisocyanate-isocyanurate, to get a two-component polyurethane flame-retardant coatings (PIPUC). Comparing physical properties of the films of PIPUC with those of film of non-flame-retardant coating, there was no deterioration observed in physical properties by the introduction of a flame-retarding component into the resin. We found that the char lengths measured by 45 deg. Meckel burner method were 3.1{approx}4.4 cm and LOI values recorded 27{approx}30%. These results indicate that the coating prepared in this study is a good flame-retardant. The surface structure of coatings investigated with SEM does not show any defects and phase separation. (author). 23 refs., 8 tabs., 3 figs.

  6. General technique for discrete retardation-modulation polarimetry

    Science.gov (United States)

    Saxena, Indu

    1993-01-01

    The general theory and rigorous solutions of the Stokes parameters of light of a new technique in time-resolved ellipsometry are outlined. In this technique the phase of the linear retarder is stepped over three discrete values over a time interval for which the Stokes vector is determined. The technique has an advantage over synchronous detection techniques, as it can be implemented as a digitizable system.

  7. [Clinical studies on pramipexol retard].

    Science.gov (United States)

    Klivényi, Péter; Vécsei, László

    2010-05-30

    Pramipexol retard is the newest drug for the treatment of Parkinson's disease. The prolonged release of the agent in this preparation allows a more continuous dopaminergic stimulation than previous preparations, without reducing the agent's already known and proven clinical efficiency. In addition, it has a more favourable adverse effect profile than previous preparations, and patient compliance can also be better as it needs to be taken only once daily. These benefits have been proven in recent clinical studies, of which the most important ones are reviewed here.

  8. Our Sedation Experience on Mentally Retarded Patients

    OpenAIRE

    Metin Alkan

    2014-01-01

    Aim: The majority of dental treatments can be performed under local anesthesia. However, sedation or general anesthesia are often required for mentally retarded patients presenting a lack of cooperation. The aim of this study was to retrospectively evaluate the outcomes of mentally retarded patients treated under sedation. Material and Method: The records of the 214 mentally retarded patients that were treated under sedation between 2010-2012 were retrospectively evaluated. The retrospective ...

  9. Non-specific X linked mental retardation.

    OpenAIRE

    Kerr, B.; Turner, G; Mulley, J.; Gedeon, A; PARTINGTON, M.

    1991-01-01

    Non-specific X linked mental retardation (MRX) is mental retardation in persons of normal physical appearance who have no recognisable features apart from a characteristic pedigree. Review of published reports shows that there is clinical variability in the degree of mental retardation within families and genetic heterogeneity, based on gene localisation, between families. We propose a classification based on genetic localisation and a set of minimal clinical features that should be recorded ...

  10. Orthopaedic Problems of the Mentally Retarded

    Science.gov (United States)

    McSweeney, Anthony

    1972-01-01

    Problems encountered by orthopedic surgeons treating the mentally retarded are identified, and cooperation among pediatricians, psychiatrists, psychologists, social workers, physiotherapists, occupational therapists, and orthopedic surgeons is recommended. (GW)

  11. Orthopaedic Problems of the Mentally Retarded

    Science.gov (United States)

    McSweeney, Anthony

    1972-01-01

    Problems encountered by orthopedic surgeons treating the mentally retarded are identified, and cooperation among pediatricians, psychiatrists, psychologists, social workers, physiotherapists, occupational therapists, and orthopedic surgeons is recommended. (GW)

  12. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  13. Intumescent Coatings as Fire Retardants

    Science.gov (United States)

    Parker, J. A.; Fohlen, G. M.; Sawko, P. M.; Fish, R. H.

    1970-01-01

    The development of fire-retardant coatings to protect surfaces which may be exposed to fire or extreme heat is a subject of intense interest to many industries. A fire-retardant paint has been developed which represents a new chemical approach for preparing intumescent coatings, and potentially, is very important to fire-prevention authorities. The requirements for a superior coating include ease of application, suitability to a wide variety of surfaces and finishes, and stability over an extended period of time within a broad range of ambient temperature and humidity conditions. These innovative coatings, when activated by the heat of a fire, react to form a thick, low-density, polymeric coating or char layer. Water vapor and sulphur dioxide are released during the intumescent reaction. Two fire-protection mechanisms thus become available: (1) the char layer retards the flow of heat, due to the extremely low thermal conductivity; and (2) water vapor and sulfur dioxide are released, providing fire quenching properties. Still another mechanism functions in cases where the char, by virtue of its high oxidation resistance and low thermal conductivity, reaches a sufficiently high temperature to re-radiate much of the incident heat load. The coatings consist of dispersions of selective salts of a nitro-amino-arornatic compound. Specifically, para-nitroaniline bisulfate and the ammonium salt of para-nitroaniline-ortho sulphuric acid (2-amino-5-nitrobenzenesulphuric acid) are used. Suitable vehicles are cellulose nitrate of lacquer grade, a nitrite-phenolic modified rubber, or epoxy-polysulfide copolymer. Three separate formulations have been developed. A solvent is usually employed, such as methylethyl ketone, butyl acetate, or toluene, which renders the coatings suitably thin and which evaporates after the coatings are applied. Generally, the intumescent material is treated as insoluble in the vehicle, and is ground and dispersed in the vehicle and solvent like an

  14. Human Sexuality for the Mentally Retarded.

    Science.gov (United States)

    Zitzow, Darryl; And Others

    The Human Sexuality for the Mentally Retarded program sought to provide cognitive awareness of human sexuality for mentally retarded trainable residents (5 to 21 years old) as well as inservice staff training regarding attitudes and cognitive awareness changes. Cognitive awareness training focused on body parts, discrimination of the sexes,…

  15. MR 76. Mental Retardation: Past and Present.

    Science.gov (United States)

    President's Committee on Mental Retardation, Washington, DC.

    The tenth annual report of the President's Committee on Mental Retardation reviews the history of America's services for the retarded from the 1850's to the present. Traced is governmental involvement through conferences on children and youth, and reviewed is the role of parents and volunteers in securing appropriate services. Among agencies…

  16. Operant Conditioning of Mental Retardates' Visual Monitoring.

    Science.gov (United States)

    Perryman, Roy E.; And Others

    1981-01-01

    To study improvement of visual monitoring of retardates, specialized training methods backed up by incentives were used. The extent to which these training techniques might be expected to produce results which would generalize was explored. Subjects were eight female mental retardates (ages 15-22) with IQs from 38 to 69. (Author/SJL)

  17. Flame retardant cotton based highloft nonwovens

    Science.gov (United States)

    Flame retardancy has been a serious bottleneck to develop cotton blended very high specific volume bulky High loft fabrics. Alternately, newer approach to produce flame retardant cotton blended High loft fabrics must be employed that retain soft feel characteristics desirable of furnishings. Hence, ...

  18. Political Philosophy and the Mentally Retarded.

    Science.gov (United States)

    Stanovich, Keith E.

    The effects of Social Darwinism, eugenics, and contemporary political conservatism on the status of advocacy efforts for the mentally retarded are reviewed. Provided are historical sketches of Social Darwinism, which viewed the retarded as members of an inferior race, and eugenics, which argued for sterilization of the "genetically…

  19. CASE REPORT OF A MENTALLY RETARDED CHILD

    Directory of Open Access Journals (Sweden)

    Vasilka GALEVSKA

    2006-06-01

    Full Text Available Mental retardation is a complex individual and social problem. According to WHO, around 1-3 % of world population are mentally retarded people and the percentage between school children is around 2 %.The development of a mentally retarded child depends on factors related to the disability itself, all the limitations and characteristics which results from that. But, physical, psychical, educational and social development of a mentally retarded child, also, depend on other conditions, such as the family and the wider environment, their reactions, attitudes, awareness and sensitivity for special needs of the child, as well as their preparedness and possibilities to respond.At the same time, it is necessary that the mentally retarded child is detected and diagnosed in time, as well as the early start of an adequate treatment.

  20. ATTITUDE OF PARENTS TOWARDS THEIR MENTALLY RETARDED CHILDREN1

    OpenAIRE

    Rastogi, C. K.

    1981-01-01

    SUMMARY Parents of 50 mentally retarded children were investigated for their attitudes towards their retarded children. Both the parents showed more negative attitudes toward their severely retarded child. In general mothers exhibited more negative attitude than the fathers.

  1. Studying the Hydration of a Retarded Suspension of Ground Granulated Blast-Furnace Slag after Reactivation

    Directory of Open Access Journals (Sweden)

    Nick Schneider

    2016-11-01

    Full Text Available This article presents a combined use of a retarder (d-gluconic acid and an alkaline activator (sodium hydroxide in a binder system based on ground granulated blast-furnace slag. The properties of the retarder are extending the dormant hydration period and suppressing the generation of strength-giving phases. Different retarder concentrations between 0.25 and 1.00 wt.% regulate the intensity and the period of the retardation and also the characteristics of the strength development. The activator concentration of 30 and 50 wt.% regulates the overcoming of the dormant period and thereby the solution of the slag and hence the formation of the hydration products. The research objective is to produce a mineral binder system based on two separate liquid components. The highest concentration of retarder and activator generates the highest compressive strength and mass of hydration products—after 90 days of hydration a compressive strength of more than 50 N/mm2. The main phases are calcium silicate hydrate and hydrotalcite. Generally, the combination of retarder and activator shows a high potential in the performance increase of the hydration process.

  2. Flame Retardant Effects of Nano-Clinoptilolite on AcrylonitrileButadiene-Styrene (ABS Nano-Composite

    Directory of Open Access Journals (Sweden)

    Aboulfazl Barati

    2012-01-01

    Full Text Available In recent years, intumescent technology has found a place in polymer science as a method of providing flame retardance to polymeric materials. On heating, fire-retardant intumescent material restricts the action of the heat flux or flame. The proposed mechanism is based on charred layer acting as physical barrier, which slows down heat and mass transfer between the gas and the condensed phases. In this paper, the flammability of intumescent fire-retardant acrylonitrile-butadiene-styrene (ABS matrix composites consisting of hydromagnesite (HMg as an acid source and blowing agent, pentaerythritol (PER as a carbonisation agent and natural zeolite (clinoptilolite rich, Kansar Shargh as a synergistic agent were examined. The flammability of composites was characterized by limiting oxygen index (LOI measurement and horizontal burning tests. A synergistic effect in flame retardancy was observed when natural zeolites were used in combination with HMg and PER.

  3. A Thermogravimetric Study of Cotton Fabric Flame-Retardancy by Means of Impregnation with Red Phosphorus

    Institute of Scientific and Technical Information of China (English)

    MOSTASHARI,S.M.; FAYYAZ,F.

    2008-01-01

    The effect of red phosphorus was found to be effective for flame-retardancy of a pure cotton fabric.The laundered bone-dried weighed samples were impregnated with red phosphorus at suitable concentrations.Vertical flame spread test was accomplished.The optimum add-on value to impart flame-retardancy onto cotton fabric was determined around 3.95 g of red phosphorus per 100 g of fabric.TG/DTG curves of treated samples showed a well-timed weight loss occurred with regard to untreated specimens.This illustrates the sufficiency of impregnation and support its catalytic action on flame-retardancy,which is compliance with data obtained via flammability test.The resuits are in favor of "Chemical Action Theory","Gas Theory" and "Condensed Phase Retardation".

  4. SEXUAL ABUSE OF PEOPLE WITH MENTAL RETARDATION

    Directory of Open Access Journals (Sweden)

    Olivera RASHICH

    2006-12-01

    Full Text Available People from the”Normal“ population don't have enough knowledge about the problems caused by mental retardation. Very often they have wrong sense and biases about mentally retarded people, considering them as people who suffer from pshychic illness. Mentally retarded people, very often are considered very different from the ”Normal“ population, but if we come closer to them we will see that there are more similarities than differences. The period in which we live today is full of challenges and fulfillments, which are frightening for people with mental retardation. It will be logical if the progress and contemporary techniques and the society go together with progress of human relationships, but, in fact, we are witnesses of lots of unhuman acts. The number of mental retarded people who have been victims of sexual abuse increases more and more everyday, and the most tragic is that they are not even aware of the situation in most cases. Persons with mental retardation in most situations become victims of this kind of unhuman acts because they don't know to say ”No“ to adults.This paper is a supplement for investigations about frequency, reasons and possibilities for prevention of sexual abuse of people with mental retardation.

  5. Identification of flame retardants in polyurethane foam collected from baby products.

    Science.gov (United States)

    Stapleton, Heather M; Klosterhaus, Susan; Keller, Alex; Ferguson, P Lee; van Bergen, Saskia; Cooper, Ellen; Webster, Thomas F; Blum, Arlene

    2011-06-15

    With the phase-out of PentaBDE in 2004, alternative flame retardants are being used in polyurethane foam to meet flammability standards. However, insufficient information is available on the identity of the flame retardants currently in use. Baby products containing polyurethane foam must meet California state furniture flammability standards, which likely affects the use of flame retardants in baby products throughout the U.S. However, it is unclear which products contain flame retardants and at what concentrations. In this study we surveyed baby products containing polyurethane foam to investigate how often flame retardants were used in these products. Information on when the products were purchased and whether they contained a label indicating that the product meets requirements for a California flammability standard were recorded. When possible, we identified the flame retardants being used and their concentrations in the foam. Foam samples collected from 101 commonly used baby products were analyzed. Eighty samples contained an identifiable flame retardant additive, and all but one of these was either chlorinated or brominated. The most common flame retardant detected was tris(1,3-dichloroisopropyl) phosphate (TDCPP; detection frequency 36%), followed by components typically found in the Firemaster550 commercial mixture (detection frequency 17%). Five samples contained PBDE congeners commonly associated with PentaBDE, suggesting products with PentaBDE are still in-use. Two chlorinated organophosphate flame retardants (OPFRs) not previously documented in the environment were also identified, one of which is commercially sold as V6 (detection frequency 15%) and contains tris(2-chloroethyl) phosphate (TCEP) as an impurity. As an addition to this study, we used a portable X-ray fluorescence (XRF) analyzer to estimate the bromine and chlorine content of the foam and investigate whether XRF is a useful method for predicting the presence of halogenated flame

  6. A, a Brominated Flame Retardant

    Directory of Open Access Journals (Sweden)

    Tomomi Takeshita

    2013-01-01

    Full Text Available Tetrabromobisphenol A (TBBPA, a brominated flame retardant, has been found to exacerbate pneumonia in respiratory syncytial virus- (RSV- infected mice. We examined the effect of Brazilian propolis (AF-08 on the exacerbation of RSV infection by TBBPA exposure in mice. Mice were fed a powdered diet mixed with 1% TBBPA alone, 0.02% AF-08 alone, or 1% TBBPA and 0.02% AF-08 for four weeks and then intranasally infected with RSV. TBBPA exposure increased the pulmonary virus titer and level of IFN-γ, a representative marker of pneumonia due to RSV infection, in the lungs of infected mice without toxicity. AF-08 was significantly effective in reducing the virus titers and IFN-γ level increased by TBBPA exposure. Also, AF-08 significantly reduced proinflammatory cytokine (TNF-α and IL-6 levels in the lungs of RSV-infected mice with TBBPA exposure, but Th2 cytokine (IL-4 and IL-10 levels were not evidently increased. Neither TBBPA exposure nor AF-08 treatment affected the anti-RSV antibody production in RSV-infected mice. In flow cytometry analysis, AF-08 seemed to be effective in reducing the ratio of pulmonary CD8a+ cells in RSV-infected mice with TBBPA exposure. TBBPA and AF-08 did not exhibit anti-RSV activity in vitro. Thus, AF-08 probably ameliorated pneumonia exacerbated by TBBPA exposure in RSV-infected mice by limiting excess cellular immune responses.

  7. Video Tape and the Mentally Retarded

    Science.gov (United States)

    Weisbord, H. F.

    1972-01-01

    Three uses of video tape recordings with the mentally retarded; discussed briefly are staff training or teacher education, parental involvement in the child's education, and therapeutic uses by psychiatrists and psychologists. (CB)

  8. Intrauterine growth retardation - small events, big consequences

    Directory of Open Access Journals (Sweden)

    Ali Syed R

    2011-09-01

    Full Text Available Abstract Intrauterine growth retardation refers to a rate of growth of a fetus that is less than normal for the growth potential of a fetus (for that particular gestational age. As one of the leading causes of perinatal mortality and morbidity, intrauterine growth retardation has immense implications for the short term and long term growth of children. It is an important public health concern in the developing countries. Health statistics encompassing parameters for maternal and child health in the Indian subcontinent have shown improvement in the past few years but they are still far from perfect. Maternal health, education and empowerment bears a strong influence on perinatal outcomes including intrauterine growth retardation and should be the primary focus of any stratagem targeted at reducing the incidence of intrauterine growth retardation. A concerted liaison of various medical and social disciplines is imperative in this regard.

  9. Cortical Response of Retardates for AER Audiometry

    Science.gov (United States)

    Hogan, Donald D.

    1971-01-01

    Averaged auditory evoked responses were obtained from 15 retarded and motor-handicapped subjects and from 15 nonretarded subjects in order to investigate comparative responsiveness and response features. (Author)

  10. Approximations of solutions to retarded integrodifferential equations

    Directory of Open Access Journals (Sweden)

    Dhirendra Bahuguna

    2004-11-01

    Full Text Available In this paper we consider a retarded integrodifferential equation and prove existence, uniqueness and convergence of approximate solutions. We also give some examples to illustrate the applications of the abstract results.

  11. Inequalities applicable to retarded Volterra integral equations

    Directory of Open Access Journals (Sweden)

    B. G. Pachpatte

    2004-12-01

    Full Text Available The main objective of this paper is to establish explicit bounds on certain integral inequialities which can be used as tools in the study of certain classes of retarded Volterra integral equations.

  12. Video Tape and the Mentally Retarded

    Science.gov (United States)

    Weisbord, H. F.

    1972-01-01

    Three uses of video tape recordings with the mentally retarded; discussed briefly are staff training or teacher education, parental involvement in the child's education, and therapeutic uses by psychiatrists and psychologists. (CB)

  13. ON SOME RETARDED INTEGRAL INEQUALITIES AND APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We establish explicit bounds on some more general retarded integral inequalities which can be used as convenient tools in some applications, and give some examples which show the feasibility of our results.

  14. Opitz C syndrome: Trigonocephaly, mental retardation and ...

    African Journals Online (AJOL)

    J.A. Avina Fierro

    2015-06-09

    Jun 9, 2015 ... including speech delay and early motor development retarded; she rolled over at age ... alized hypotonia, clumsiness and awkward movements, global ... ular monitoring of growth and receives speech therapy, her cognitive ...

  15. Multistage Pressure-Retarded Osmosis

    Science.gov (United States)

    Bharadwaj, Devesh; Fyles, Thomas M.; Struchtrup, Henning

    2016-10-01

    One promising sustainable energy source is the chemical potential difference between salt and freshwater. The membrane process of pressure-retarded osmosis (PRO) has been the most widely investigated means to harvest salinity gradient energy. In this report, we analyse the thermodynamic efficiency of multistage PRO systems to optimize energy recovery from a salinity gradient. We establish a unified description of the efficiencies of the component pumps (P), turbines (T), pressure exchangers (PX), and membrane modules (M) and exploit this model to determine the maximum available work with respect to the volume of the brine produced, the volume of the sea water consumed, or the volume of the freshwater that permeates the membrane. In an idealized series configuration of 1-20 modules (P-M-T), the three optimization conditions have significantly different intermediate operating pressures in the modules, but demonstrate that multistage systems can recover a significantly larger fraction of the available work compared to single-stage PRO. The biggest proportional advantage occurs for one to three modules in series. The available work depends upon the component efficiencies, but the proportional advantage of multistage PRO is retained. We also optimize one- and two-stage PX-M-T and P-M-T configurations with respect to the three volume parameters, and again significantly different optimal operating conditions are found. PX-M-T systems are more efficient than P-M-T systems, and two-stage systems have efficiency advantages that transcend assumed component efficiencies. The results indicate that overall system design with a clear focus on critical optimization parameters has the potential to significantly improve the near-term practical feasibility of PRO.

  16. Recent Developments in Organophosphorus Flame Retardants Containing P-C Bond and Their Applications.

    Science.gov (United States)

    Wendels, Sophie; Chavez, Thiebault; Bonnet, Martin; Salmeia, Khalifah A; Gaan, Sabyasachi

    2017-07-11

    Organophosphorus compounds containing P-C bonds are increasingly developed as flame retardant additives due to their excellent thermal and hydrolytic stability and ease of synthesis. The latest development (since 2010) in organophosphorus flame retardants containing P-C bonds summarized in this review. In this review, we have broadly classified such phosphorus compounds based on the carbon unit linked to the phosphorus atom i.e., could be a part of either an aliphatic or an aromatic unit. We have only considered those published literature where a P-C bond was created as a part of synthetic strategy to make either an intermediate or a final organophosphorus compound with an aim to use it as a flame retardant. General synthetic strategies to create P-C bonds are briefly discussed. Most popular synthetic strategies used for developing P-C containing phosphorus based flame retardants include Michael addition, Michaelis-Arbuzov, Friedels-Crafts and Grignard reactions. In general, most flame retardant derivatives discussed in this review have been prepared via a one- to two-step synthetic strategy with relatively high yields greater than 80%. Specific examples of P-C containing flame retardants synthesized via suitable synthetic strategy and their applications on various polymer systems are described in detail. Aliphatic phosphorus compounds being liquids or low melting solids are generally applied in polymers via coatings (cellulose) or are incorporated in the bulk of the polymers (epoxy, polyurethanes) during their polymerization as reactive or non-reactive additives. Substituents on the P atoms and the chemistry of the polymer matrix greatly influence the flame retardant behavior of these compounds (condensed phase vs. the gas phase). Recently, aromatic DOPO based phosphinate flame retardants have been developed with relatively higher thermal stabilities (>250 °C). Such compounds have potential as flame retardants for high temperature processable polymers such as

  17. A Study on Normal Siblings of Mentally Retarded Persons

    OpenAIRE

    1997-01-01

    This study examined how normal people perceive their mentally retarded siblings and what they see to be their future relationship. Normal siblings of mentally retarded persons were given a questionnaire regarding their relationships with their parents and mentally retarded siblings during childhood and how they introduced their mentally retarded siblings to their fiancees. In most cases, they had good relationships with their mentally retarded siblings during childhood. Most of them also inte...

  18. Preparation and Properties of Graphene Straw Retardant Composites

    Directory of Open Access Journals (Sweden)

    Xiao Li-guang

    2016-01-01

    Full Text Available This article was prepared by spin-coating the evaporation process graphene oxide having a shell core structure GO/straw flame retardant composite materials, through the oxygen index apparatus and SEM measured the relationship between the flame retardant properties and the morphological structure of the flame retardant composite material, the experiment preparation process is simple, environmentally friendly non-toxic, and the resulting GO/straw flame retardant composite material having a high fire retardant properties.

  19. Synergistic Flame Retardancy of Aluminium Dipropylphosphinate and Melamine in Polyamide 6

    Directory of Open Access Journals (Sweden)

    Linsheng Tang

    2013-01-01

    Full Text Available The synergistic flame retardancy of aluminium dipropylphosphinate (ADPP and melamine (ME in polyamide 6 (PA6 was studied by the limiting oxygen index (LOI measurement, the vertical burning test, and the cone calorimeter test, and the mechanism was also discussed by thermogravimetric and residual analyses. The experimental results indicated that there was obvious synergistic flame retardancy between ADPP and ME under their appropriate weight ratios. The thermogravimetric results and the analysis of the residues obtained in cone calorimeter test showed that ADPP and ADPP/ME played the role of flame retardance by gaseous- and condensed-phase mechanisms, where, on one hand, they were decomposed into nonvolatile aluminum phosphate and promoted the carbonization of PA6, and the formed intumescent layer resulted in flame retardancy by the barrier effect on heat, air, and decomposition products, and on the other hand, they were decomposed into volatile phosphorus compounds which bring about flame retardancy by flame inhibition. Using a combination of ADPP and ME improved charring of PA6 and raised the residual rate of P and Al, thus, improving the barrier effect in the condensed phase.

  20. Analysis of retarding effect on α to γ transformation in Fe–C alloy by addition of dispersed particles

    Directory of Open Access Journals (Sweden)

    Liang Chen

    2015-06-01

    Full Text Available The effects of dispersed second phase particles on α-ferrite (α to austenite (γ transformation at 1140 K in Fe–C alloy were studied by means of phase field simulation. According to the simulated results, it was found that the particle could retard the migration of α/γ interface. Importantly, both the morphology of particles and the interfacial energy of particle/matrix (α or γ interface affect the magnitude of the retarding effect. More specifically, the particles with smaller aspect ratio bring stronger retarding force, and when the interfacial energy of particle/γ interface is larger than that of particle/α interface, the retarding effect also becomes significant. These phenomena could be explained from the viewpoint of change in the total amount of the interfacial energy of the simulation system.

  1. Inlfuence of Compound Flame Retardant on Flame Retardant Properties of Rigid Polyurethane Foam%复配阻燃剂对硬质聚氨酯泡沫塑料阻燃性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘伟

    2016-01-01

    研究了甲基膦酸二甲酯(DMMP)、尿素(UC)、磷酸三乙酯(TEP)单独添加及复配使用对硬质聚氨酯泡沫塑料(RPUF)阻燃性能的影响。结果表明,UC与DMMP及TEP复配是气相和凝聚相双相协同阻燃机理的复合阻燃剂;UC与DMMP,UC与TEP复配阻燃RPUF,可达到垂直燃烧分级V0级;UC/DMMP复配使用,UC和DMMP含量分别为15%和25%时,其阻燃RPUF的氧指数最高,为27.3%,阻燃性能优于UC/TEP复配阻燃RPUF;复配阻燃RPUF的压缩强度比单独填充UC体系高,呈现协同作用。%The effects of methyl phosphonic acid dimethyl ester (DMMP),urea (UC),triethyl phosphate (TEP) and their compounds on the flame retardancy of rigid polyurethane foam (RPUF) were studied. The results show that the UC and DMMP mixture,UC and TEP mixture are composite flame retardant agents of gas phase and condensed phase double coordinate flame retardant mechanism. UC and DMMP,UC and TEP compound flame retardant RPUF can achieve the vertical combustion grade V0. When UC is compound with DMMP,and the content of UC and DMMP is 15% and 25% respectively, the flame retardant RPUF has the highest oxygen index of 27.3%,the flame retardancy is better than that of UC/TEP flame retardant RPUF. The compressive strength of compound flame retardant RPUF is higher than that of UC alone flame retardant system.

  2. Self-Injurious Behavior within the Menstrual Cycle of Women with Mental Retardation.

    Science.gov (United States)

    Taylor, Derek V.; And Others

    1993-01-01

    Catamenial and behavioral records of nine women with mental retardation who exhibited self-injurious behavior (SIB) were analyzed for six months. Analysis confirmed that SIB was cyclic across the menstrual cycle, with the highest frequency occurring in the early follicular and late follicular phases. (Author/JDD)

  3. Thermal damping and retardation in karst conduits

    Directory of Open Access Journals (Sweden)

    A. J. Luhmann

    2014-08-01

    Full Text Available Water temperature is a non-conservative tracer in the environment. Variations in recharge temperature are damped and retarded as water moves through an aquifer due to heat exchange between water and rock. However, within karst aquifers, seasonal and short-term fluctuations in recharge temperature are often transmitted over long distances before they are fully damped. Using analytical solutions and numerical simulations, we develop relationships that describe the effect of flow path properties, flow-through time, recharge characteristics, and water and rock physical properties on the damping and retardation of thermal peaks/troughs in karst conduits. Using these relationships, one can estimate the thermal retardation and damping that would occur under given conditions with a given conduit geometry. Ultimately, these relationships can be used with thermal damping and retardation field data to estimate parameters such as conduit diameter. We also examine sets of numerical experiments where we relax some of the assumptions used to develop these relationships, testing the effects of variable diameter, variable velocity, open channels, and recharge shape on thermal damping and retardation to provide some constraints on uncertainty. Finally, we discuss a tracer experiment that provides field confirmation of our relationships. High temporal resolution water temperature data are required to obtain sufficient constraints on the magnitude and timing of thermal peaks and troughs in order to take full advantage of water temperature as a tracer.

  4. [Clinical features of strabismus in psychomotor retardation].

    Science.gov (United States)

    Arias-Cabello, Belina; Arroyo-Yllanes, María Estela; Pérez-Pérez, José Fernando; Fonte-Vázquez, Anselmo

    2016-01-01

    In psychomotor retardation there is an abnormal development of mental, sensory and motor skills associated with ocular manifestations. There are biological and psychosocial risk factors that predispose an individual to neurological damage. From 50% to 80% of patients with strabismus retardation have special features that differentiate it from the rest of strabismus in healthy patients. To determine the most common type of strabismus in patients with psychomotor retardation and their clinical features. Patients with psychomotor retardation and strabismus were included. An ophthalmological examination was performed, as well as an evaluation of the characteristics of strabismus, including perinatal and post-natal history. Esotropia was the most frequent squint with 65.3%, followed by exotropia with 32.7%. The variability in the squint magnitude was 60% in both types, and 6 patients had dissociated vertical deviation. Most of the patients started to present strabismus since they were born. The most frequent perinatal risk factors were threatened miscarriage, pre-eclampsia, foetal distress, and hypoxia. Esotropia is the most common type of strabismus in psychomotor retardation. The variability of squint magnitude is a characteristic in these patients. The moderate variability is the most frequent in both esotropia and exotropia. The most common refractive error is hyperopic astigmatism in esotropia and the myopic kind in exotropia. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.

  5. Coherence and polarization speckle generated by a rough-surfaced retardation plate depolarizer

    DEFF Research Database (Denmark)

    Ma, Ning; Hanson, Steen Grüner; Takeda, Mitsuo

    2015-01-01

    The coherence and polarization of polarization speckle, arising from a stochastic electromagnetic field with random change of polarization, modulated by a depolarizer are examined on the basis of the coherence matrix. The depolarizer is a rough-surfaced retardation plate with a random function...... of position introducing random phase differences between the two orthogonal components of the electric vector. Under the assumption of Gaussian statistics with zero mean, the surface model for the depolarizer of the rough-surfaced retardation plate is obtained. The propagation of the modulated fields through...

  6. CHARACTERISTICS OF THE LIGHTLY MENTALLY RETARDED PERSONS

    Directory of Open Access Journals (Sweden)

    Goran AJDINSKI

    1998-09-01

    Full Text Available Bearing in mind the fact that many scientific researches, the mental retardation are treated as a complex and specific human phenomenon, the author of this paper likes to point out three basic questions. Those are the definition of mental retardation, classification of the some of the characteristics of the mentally retarded persons.In connection with this questions practically all of the former awareness is presented and also for this aim is used a huge list of literature.Here is made a synthesis of many opinions of the eminent authors. With this presentation, concerned specialists, parents and students could be acquaintance with most important facts about the mentioned problems, which are elaborated in this paper.

  7. Laser Feedback Technique for Precise Retardation Measurements

    Institute of Scientific and Technical Information of China (English)

    FEI Li-Gang; ZHANG Shu-Lian

    2006-01-01

    @@ A simple and precise retardation measurement based on laser feedback is demonstrated. The measurement principle is based on polarization flipping induced by optical feedback from an external birefringence cavity.The measured wave plate is located in the external cavity. When the length of the external cavity is tuned,the polarization states of laser will flip between two eigenstates, and the position of polarization flipping in one period of intensity modulation will vary with retardation of the wave plate. The duty ratio of two eigenstates is used to determine the retardation. Main advantages of the technique are that it is compact, low cost, fast and flexible. Especially, it is insensitive to a fluctuation of laser intensity and is suitable for on-line measurement. The experimental results have shown that the measurement uncertainty is better than 0.03° in the range 30°-150°.

  8. "Idiopathic" mental retardation and new chromosomal abnormalities.

    Science.gov (United States)

    Galasso, Cinzia; Lo-Castro, Adriana; El-Malhany, Nadia; Curatolo, Paolo

    2010-02-14

    Mental retardation is a heterogeneous condition, affecting 1-3% of general population. In the last few years, several emerging clinical entities have been described, due to the advent of newest genetic techniques, such as array Comparative Genomic Hybridization. The detection of cryptic microdeletion/microduplication abnormalities has allowed genotype-phenotype correlations, delineating recognizable syndromic conditions that are herein reviewed. With the aim to provide to Paediatricians a combined clinical and genetic approach to the child with cognitive impairment, a practical diagnostic algorithm is also illustrated. The use of microarray platforms has further reduced the percentage of "idiopathic" forms of mental retardation, previously accounted for about half of total cases. We discussed the putative pathways at the basis of remaining "pure idiopathic" forms of mental retardation, highlighting possible environmental and epigenetic mechanisms as causes of altered cognition.

  9. Plasma impregnation of wood with fire retardants

    Science.gov (United States)

    Pabeliña, Karel G.; Lumban, Carmencita O.; Ramos, Henry J.

    2012-02-01

    The efficacy of chemical and plasma treatments with phosphate and boric compounds, and nitrogen as flame retardants on wood are compared in this study. The chemical treatment involved the conventional method of spraying the solution over the wood surface at atmospheric condition and chemical vapor deposition in a vacuum chamber. The plasma treatment utilized a dielectric barrier discharge ionizing and decomposing the flame retardants into innocuous simple compounds. Wood samples are immersed in either phosphoric acid, boric acid, hydrogen or nitrogen plasmas or a plasma admixture of two or three compounds at various concentrations and impregnated by the ionized chemical reactants. Chemical changes on the wood samples were analyzed by Fourier transform infrared spectroscopy (FTIR) while the thermal changes through thermo gravimetric analysis (TGA). Plasma-treated samples exhibit superior thermal stability and fire retardant properties in terms of highest onset temperature, temperature of maximum pyrolysis, highest residual char percentage and comparably low total percentage weight loss.

  10. AN EVA/UNMODIFIED NANO-MAGNESIUM HYDROXIDE/SILICONE RUBBER NANOCOMPOSITE WITH SYNERGISTIC FLAME RETARDANCY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel EVA/unmodified nano-magnesium hydroxide (NMH)/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubbet (CFR).The flammability of the ternary composite was studied by cone calorimeter test (CCT).Synergistic effect on flame retardancy was found between silicone rubber and NMH.EVA/CFR ternary nanocomposite showed the lowest peak heat release rate (PHRR) and mass loss rate (MLR) among the samples of virgin EVA,EVA composites.The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.

  11. Intrinsic Flame-Retardant and Thermally Stable Epoxy Endowed by a Highly Efficient, Multifunctional Curing Agent

    Directory of Open Access Journals (Sweden)

    Chunlei Dong

    2016-12-01

    Full Text Available It is difficult to realize flame retardancy of epoxy without suffering much detriment in thermal stability. To solve the problem, a super-efficient phosphorus-nitrogen-containing reactive-type flame retardant, 10-(hydroxy(4-hydroxyphenylmethyl-5,10-dihydrophenophosphazinine-10-oxide (HB-DPPA is synthesized and characterized. When it is used as a co-curing agent of 4,4′-methylenedianiline (DDM for curing diglycidyl ether of bisphenol A (DGEBA, the cured epoxy achieves UL-94 V-0 rating with the limiting oxygen index of 29.3%. In this case, the phosphorus content in the system is exceptionally low (0.18 wt %. To the best of our knowledge, it currently has the highest efficiency among similar epoxy systems. Such excellent flame retardancy originates from the exclusive chemical structure of the phenophosphazine moiety, in which the phosphorus element is stabilized by the two adjacent aromatic rings. The action in the condensed phase is enhanced and followed by pressurization of the pyrolytic gases that induces the blowing-out effect during combustion. The cone calorimeter result reveals the formation of a unique intumescent char structure with five discernible layers. Owing to the super-efficient flame retardancy and the rigid molecular structure of HB-DPPA, the flame-retardant epoxy acquires high thermal stability and its initial decomposition temperature only decreases by 4.6 °C as compared with the unmodified one.

  12. CITRIC ACID AS A SET RETARDER FOR CALCIUM ALUMINATE PHOSPHATE CEMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.; BROTHERS, L.E.

    2005-01-01

    Citric acid added as set retarder significantly contributed to enhancing the setting temperature and to extending the thickening time of a calcium aluminate phosphate (CaP) geothermal cement slurry consisting of calcium aluminate cement (CAC) as the base reactant and sodium polyphosphate (NaP) solution as the acid reactant. The set-retarding activity of citric acid was due to the uptake of Ca{sup 2+} ions from the CAC by carboxylic acid groups within the citric acid. This uptake led to the precipitation of a Ca-complexed carboxylate compound as a set-retarding barrier layer on the CAC grains' surfaces. However, this barrier layer was vulnerable to disintegration by the attack of free Ca{sup 2+} ions from CAC, and also to degradation at elevated temperature, thereby promoting the generation of exothermic energy from acid-base reactions between the CAC and NaP after the barrier was broken. The exothermic reaction energy that was promoted in this way minimized the loss in strength of the citric acid-retarded cement. The phase composition assembled in both retarded and non-retarded cements after autoclaving at 180 C encompassed three reaction products, hydroxyapatite (HOAp), hydrogrossular and boehmite, which are responsible for strengthening the autoclaved cement. The first two reaction products were susceptible to reactions with sulfuric acid and sodium sulfate to form crystalline bassanite scale as the corrosion product. The boehmite phase possessed a great resistance to acid and sulfate. Although the bassanite scales clinging to the cement's surfaces were the major factor governing the loss in weight, they served in protecting the cement from further acid- and sulfate-corrosion until their spallation eventually occurred. Nevertheless, the repetitive processes of HOAp and hydrogrossular {yields} bassanite {yields} spallation played an important role in extending the useful lifetime of CaP cement in a low pH environment at 180 C.

  13. Euthanasia and Mental Retardation: Suggesting the Unthinkable.

    Science.gov (United States)

    Hollander, Russell

    1989-01-01

    The article examines current opinions toward euthanasia of persons with mental retardation in light of the history of public and professional attitudes. It also discusses the rejection of euthanasia on moral and religious grounds, and notes the use of lifelong incarceration, based on eugenics principles, to accomplish similar ends. (DB)

  14. PENETRATING KERATOPLASTY IN MENTALLY RETARDED PATIENTS

    Directory of Open Access Journals (Sweden)

    Dušica Pahor

    2002-12-01

    Full Text Available Background. Penetrating keratoplasty (PK is rarely performed in mentally retarded patients, first of all because of numerous complications after surgery such as inflammation, self-inflicted injury, injury and because of difficult post-operative treatment. The aim of this study was to present the success of PK in this patients. In 16 years (from May 1984 to May 2000 201 PK were performed, but only three in mentally retarded patients.Methods. We present three cases of PK in mentally retarded patients. All the patients were men. They were 14, 16 and 27 year old. The indication for PK were in two cases acute keratoconus and in one case acute keratoglobus. The mean followup was 24.6 months. Trepanation was made with rotor threpin and donor material was sutured using single continuous 10-0 nylon suture.Results. In two cases keratoplasties stayed clear. Visual acuities were 0,4 and 0,5. In one patient with very aggressive behaviour graft failure developed with significant corneal vascularisation. Re-keratoplasty was not performed.Conclusions. Adequate post-operative care following PK in mentally retarded patients is the most important factor for the success of transplantation. The indication for the surgery must be made very carefully especially in self-aggressive patients in residential care.

  15. Puberty in the Girl Who is Retarded.

    Science.gov (United States)

    Pattullo, Ann

    Designed to help mothers of mentally retarded girls deal with the problems and concerns of puberty, the booklet provides information on physical and emotional changes, menstruation, masturbation, heterosexual behavior, contraception, protection against sexual aggression, the possibilities of marriage, and additional sources of information.…

  16. Language Transference by Mentally Retarded Spanish Speakers.

    Science.gov (United States)

    Flaherty, Carol

    In an investigation of language transference vs. language interference, 12 trainable mentally retarded Spanish speakers (5 to 9 years old) were trained to name in English objects previously identified receptively and objects not previously identified receptively in Spanish. Results indicated no significant difference in the number of words learned…

  17. Flame retardant cotton barrier nonwovens for mattresses

    Science.gov (United States)

    According to regulation CPSC 16 CFR 1633, every new residential mattress sold in the United States since July 2007 must resist ignition by open flame. An environmentally benign “green”, inexpensive way to meet this regulation is to use a low-cost flame retardant (FR) barrier fabric. In this study, a...

  18. Brominated flame retardants and endocrine disruption

    NARCIS (Netherlands)

    Vos, J.G.; Becher, G.; Berg, van den M.; Boer, de J.; Leonards, P.E.G.

    2003-01-01

    From an environmental point of view, an increasing important group of organohalogen compounds are the brominated flame retardants (BFRs), which are widely used in polymers and textiles and applied in construction materials, furniture, and electronic equipment. BFRs with the highest production volume

  19. Teaching Mending Skills to Mentally Retarded Adolescents.

    Science.gov (United States)

    Cronin, Kathleen A.; Cuvo, Anthony J.

    1979-01-01

    A task analysis model for analyzing and teaching community living skills to the mentally handicapped was developed and validated with five moderately retarded youths (ages 17 to 20 years) who were taught mending skills (sewing hems, buttons, and seams). (Author/DLS)

  20. Let the Mentally-Retarded Shine

    Institute of Scientific and Technical Information of China (English)

    GONG BORONG

    2007-01-01

    @@ Of all the people with disabilities, the mentallyretarded not only are the most difficult to be part of the society and to get jobs but also add to the family burdens. This has become a big headache for Shanghai, the leading industrial city of China, which has about 70,000 mentally-retarded among the 520,000 persons with disabilities.

  1. Euthanasia and Mental Retardation: Suggesting the Unthinkable.

    Science.gov (United States)

    Hollander, Russell

    1989-01-01

    The article examines current opinions toward euthanasia of persons with mental retardation in light of the history of public and professional attitudes. It also discusses the rejection of euthanasia on moral and religious grounds, and notes the use of lifelong incarceration, based on eugenics principles, to accomplish similar ends. (DB)

  2. Psychomotor Retardation in Elderly Untreated Depressed Patients

    NARCIS (Netherlands)

    Beheydt, L.L.; Schrijvers, D.L.; Docx, L.; Bouckaert, F.; Hulstijn, W.; Sabbe, B.G.C.

    2015-01-01

    BACKGROUND: Psychomotor retardation (PR) is one of the core features in depression according to DSM V (1), but also aging in itself causes cognitive and psychomotor slowing. This is the first study investigating PR in relation to cognitive functioning and to the concomitant effect of depression and

  3. Genetic and epigenetic defects in mental retardation.

    NARCIS (Netherlands)

    Kramer, J.M.; Bokhoven, H. van

    2009-01-01

    Mental retardation (MR) is a highly diverse group of cognitive disorders. The high incidence of MR, 2-3% in most populations, and the high burden for families and society makes this condition one of the major unsolved problems in modern medicine. Gene defects account for about half of all patients a

  4. MENTAL RETARDATION. CATALOG OF LIBRARY ACCESSIONS.

    Science.gov (United States)

    FEARON, ROSS E.

    LISTING ABOUT 570 ITEMS, THIS BIBLIOGRAPHY REPRESENTS THE MENTAL RETARDATION COLLECTION AT MANTOR LIBRARY, FARMINGTON STATE COLLEGE. ITEMS ARE LISTED BY DEWEY DECIMAL CLASSIFICATION NUMBER OR VERTICAL FILE NUMBER, INCLUDED ARE CURRICULUM AND TEACHER GUIDES, PROGRAM DESCRIPTIONS, PARENT HANDBOOKS, CONFERENCE PROCEEDINGS, DIRECTORIES, RESEARCH…

  5. Theories of Dual Diagnosis in Mental Retardation.

    Science.gov (United States)

    Matson, Johnny L.; Sevin, Jay A.

    1994-01-01

    Provides historical review of theory development in the field of dual diagnosis, defined as co-occurrence of mental health disorders with mental retardation. Noting that current etiological theories have practical implications for treatment and prevention of dual diagnosis, discusses current status of etiological theories and future directions for…

  6. Daphnid life cycle response to new generation of flame retardants

    NARCIS (Netherlands)

    Waaijers, S.L.; Bleyenberg, T.E.; Dits, A; Schoorl, M.; Schütt, J; Kools, S.A.E.; de Voogt, P.; Admiraal, W.; Parsons, J.R.; Kraak, M.H.S.

    2013-01-01

    Relatively hazardous brominated flame retardants (BFRs) are currently substituted with halogen-free flame retardants (HFFRs). Consequently, information on their persistence, bioaccumulation and toxicity (PBT) is urgently needed. Therefore, we investigated the chronic toxicity to the water flea

  7. Preparation of Flame Retardant Modified with Titanate for Asphalt Binder

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available Improving the compatibility between flame retardant and asphalt is a difficult task due to the complex nature of the materials. This study explores a low dosage compound flame retardant and seeks to improve the compatibility between flame retardants and asphalt. An orthogonal experiment was designed taking magnesium hydroxide, ammonium polyphosphate, and melamine as factors. The oil absorption and activation index were tested to determine the effect of titanate on the flame retardant additive. The pavement performance test was conducted to evaluate the effect of the flame retardant additive. Oxygen index test was conducted to confirm the effect of flame retardant on flame ability of asphalt binder. The results of this study showed that the new composite flame retardant is more effective in improving the compatibility between flame retardant and asphalt and reducing the limiting oxygen index of asphalt binder tested in this study.

  8. US Forest Service Aerial Fire Retardant Hydrographic Avoidance Areas: Aquatic

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map services on the www depicting aerial retardant avoidance areas for hydrographic feature data. Aerial retardant avoidance area for hydrographic feature data are...

  9. US Forest Service Aerial Fire Retardant Avoidance Areas: Terrestrial

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map service depicting aerial fire retardant avoidance areas delivered as part of the 2011 Nationwide Aerial Application of Fire Retardant on National Forest System...

  10. Preparation and characterizations of flame retardant polyamide 66 fiber

    Science.gov (United States)

    Li, Y. Y.; Liu, K.; Xiao, R.

    2017-06-01

    The polyamide 66 (PA66) is one of the most important thermoplastic materials, but it has the drawback of flammability. So the flame retardant PA66 was prepared by condensation polymerization using nylon salt and DOPO-based flame retardant in this paper. Then the flame retardant PA66 fiber was manufactured via melt spinning. The properties of flame retardant PA66 and flame retardant PA66 fiber were investigated by relative viscosity, differential scanning calorimetry (DSC), tensile test, vertical burning test (UL94) and limiting oxygen index (LOI) test. Although the loading of the DOPO-based flame retardant decreased the molecular weight, the melting temperature, the crystallinity and the mechanical properties of flame retardant PA66, the flame retardancy properties improved. The flame retardant PA66 loaded with 5.5 wt% of DOPO-based flame retardant can achieve a UL94 V-0 rating with a LOI value of 32.9%. The tenacity at break decreased from 4.51 cN·dtex-1 for PA66 fiber to 2.82 cN·dtex-1 for flame retardant PA66 fiber which still satisfied the requirements for fabrics. The flame retardant PA66 fiber expanded the application of PA66 materials which had a broad developing prospect.

  11. Conjunctive Visual Search in Individuals with and without Mental Retardation

    Science.gov (United States)

    Carlin, Michael; Chrysler, Christina; Sullivan, Kate

    2007-01-01

    A comprehensive understanding of the basic visual and cognitive abilities of individuals with mental retardation is critical for understanding the basis of mental retardation and for the design of remediation programs. We assessed visual search abilities in individuals with mild mental retardation and in MA- and CA-matched comparison groups. Our…

  12. Genetics of non-syndromic autosomal recessive mental retardation.

    Science.gov (United States)

    Afroze, Bushra; Chaudhry, Bushra

    2013-01-01

    Non-syndromic mental retardation is one of the most serious neurodevelopmental disorders, which has a serious impact not only on the affected individuals and their families but also on the health care system and society. Previously research has been more focused on the X-linked mental retardation and only recently studies have shown that non-syndromic autosomal recessive mental retardation is extremely heterogeneous and contributes much more than the X-linked mental retardation. But very little is known about the genes and loci involved in nonsyndromic autosomal recessive mental retardation than the X-linked mental retardation. To date only thirty loci and ten genes have been established associated with the non-syndromic autosomal recessive mental retardation. This short review presents an overview of the current knowledge on clinical information available for the ten genes associated with this unexplored group of genetic disorder.

  13. Psychomotor Retardation in untreated depressed elderly

    Directory of Open Access Journals (Sweden)

    Lieve Lia Beheydt

    2015-01-01

    Full Text Available Background: Psychomotor retardation (PR is one of the core features in depression according to 17 DSM V1, but also aging in itself causes cognitive and psychomotor slowing. This is the first study 18 investigating psychomotor retardation in relation to cognitive functioning and to the concomitant 19 effect of depression and aging in a geriatric population ruling out contending effects of psychotropic 20 medication. Methods: A group of 28 non-demented depressed elderly is compared to a matched 21 control group of 20 healthy elderly. All participants underwent a test battery containing clinical 22 depression measures, cognitive measures of processing speed, executive function and memory, 23 clinical ratings of psychomotor retardation and objective computerized fine motor skill-tests. 24 Statistical analysis consisted of a General Linear Method (GLM multivariate analysis of variance to 25 compare the clinical, cognitive and psychomotor outcomes of the two groups. Results: Patients 26 performed worse on all clinical, cognitive and psychomotor retardation measures. Both groups 27 showed an effect of cognitive load on fine motor function but the influence was significantly larger 28 for patients than for healthy elderly except for the initiation time. Limitations: due to the restrictive 29 inclusion criteria, only a relatively limited sample size could be obtained. Conclusion: With a 30 medication free sample, an additive effect of depression and aging on cognition and PR in geriatric 31 patients was found,. As this effect was independent of demand of effort (by varying the cognitive 32 load, it was apparently not a motivational slowing effect of depression.

  14. Pediatric alacrima, achalasia, and mental retardation.

    Science.gov (United States)

    Ornek, Kemal; Atilla, Huban; Zilelioğlu, Güler

    2002-08-01

    Absence or deficiency of tear volume (alacrima) is rarely seen in pediatric ophthalmology. It is often a part of the multiple systemic anomalies like Riley-Day syndrome and anhidrotic ectodermal dysplasia, or it may be associated with adrenal gland insufficiency, achalasia, and neurologic disorders like Allgrove's syndrome. We report on a 7-year-old girl presenting alacrima, achalasia, and mental retardation with normal adrenocortical function.

  15. Flexible PVC flame retarded with expandable graphite

    CSIR Research Space (South Africa)

    Focke, WW

    2014-02-01

    Full Text Available by the polymer matrix and the exfoliating graphite prevents the formation of a flammable air fuel mixture. Keywords: Expandable graphite; graphite oxide; graphite intercalation compound; exfoliation; thermal analysis ________________ *Corresponding author: Tel... char residue [6] and this contributes to the mechanisms of flame retardant action [5]. Expandable graphite (EG) is a partially oxidized form of graphite containing intercalated guest species (e.g., sulfuric acid anions) in-between the stacked...

  16. MRI in children with mental retardation

    Energy Technology Data Exchange (ETDEWEB)

    Soto-Ares, Gustavo; Joyes, Beatrice; Pruvo, Jean-Pierre [Department of Neuroradiology, Hopital Roger Salengro, CHRU Lille, 59037 Lille (France); Lemaitre, Marie-Pierre; Vallee, Louis [Department of Paediatric Neurology, Hopital Roger Salengro, CHRU Lille, Lille (France)

    2003-05-01

    In mental retardation (MR) an aetiological diagnosis is not always obtained despite a detailed history, physical examination and metabolic or genetic investigations. In some of these patients, MRI is recommended and may identify subtle abnormal brain findings. We reviewed the cerebral MRI of children with non-specific mental retardation in an attempt to establish a neuroanatomical picture of this disorder. Thirty children with non-specific MR were selected to undergo cerebral MRI. The examination included supratentorial axial slices, mid-sagittal images and posterior fossa coronal images. Brain malformations, midline and cerebellar abnormalities were studied. In 27 of 30 patients, the neuroimaging evaluation revealed a relatively high incidence of cerebral and posterior fossa abnormalities. The most frequent were: dysplasia of the corpus callosum (46%; hypoplasia, short corpus callosum and vertical splenium), partially opened septum pellucidum and/or cavum vergae (33%), ventriculomegaly (33%), cerebral cortical dysplasia (23%), subarachnoid space enlargement (16.6%), vermian hypoplasia (33%), cerebellar and/or vermian disorganised folia (20%), and subarachnoid spaces enlargement in the posterior fossa (20%). Other anomalies were: enlarged Virchow-Robin spaces (10%), white matter anomalies (10%) and cerebellar or vermian atrophy. MRI has shown a high incidence of subtle cerebral abnormalities and unexpected minor forms of cerebellar cortical dysplasia. Even if most of these abnormalities are considered as subtle markers of brain dysgenesis, their role in the pathogenesis of mental retardation needs further investigation. (orig.)

  17. Influence of radiation-crosslinking on flame retarded polymer materials-How crosslinking disrupts the barrier effect

    Science.gov (United States)

    Sonnier, Rodolphe; Caro-Bretelle, Anne-Sophie; Dumazert, Loïc; Longerey, Marc; Otazaghine, Belkacem

    2015-01-01

    Fire behavior of flame retardant-free and flame retarded PP/PA6 blends was studied using pyrolysis-combustion flow calorimeter, cone calorimeter and epiradiator equipped with infrared camera and pyrometer. Blends were previously γ-irradiated in presence of crosslinking agents at various doses (up to 100 kGy) in order to assess the influence of irradiation crosslinking on flame retardancy. Crosslinked specimens exhibit a solid-like behavior under high temperature gradient in cone calorimeter and then distort considerably. The influence of such a behavior depends on the material properties. When the flame retardancy is provided by heat shielding effect, heat distortion disrupts the top protective layer leading to a substantial increase of peak of heat release rate (pHRR). The barrier layer is no longer able to prevent the heat transfer to the underlying condensed phase. In other cases (flame retardant-free blends or flame retardancy provided by other effects than heat shielding), heat distortion has negligible influence on heat release rate curves in cone calorimeter tests.

  18. Parenting provided by adults with mental retardation.

    Science.gov (United States)

    Dowdney, L; Skuse, D

    1993-01-01

    Studies assessing the quality of parenting provided by adults with mental retardation present conflicting conclusions. Some consider the majority to be doing reasonably well, whilst others report frequently unsatisfactory caretaking. There are a number of reasons for such different views. First, inconsistent selection criteria make it hard to compare across studies. In particular, sample composition will be influenced by the recruitment source. For example, if parents have been chosen from voluntary educational programmes a rather different picture is likely to be found than if they have been selected from individuals known to, or referred by, statutory agencies. On the whole, authors working with subjects from the former source have been rather more optimistic than those working with parents referred because there were already serious concerns about parenting difficulties or about delayed child development. Secondly, the majority of studies have used poorly defined global measures of parenting, with variable criteria of what constitutes adequate care. Some have concentrated on physical care and hygiene, whilst others have looked for the presence of affection and warmth. A child's reception into care as the sole measure of the quality of parenting is an unsatisfactory criterion because parental retardation has itself occasionally been used as the basis for removal of a child into care, even in the absence of other evidence of neglect or abuse. Thirdly, methodological flaws are found in studies that have used observational assessments of parenting. Such studies have suggested mothers with mental retardation tend to lack interactive skills (such as high levels of praise and imitation, and low restrictiveness) which are known to be associated with optimal child development. Control groups have often not been matched on social and other variables which might be expected to exert a significant influence upon parenting practices. In addition, the generalisability of

  19. Assessing Pediatric Nurses' Knowledge About Chemical Flame Retardants.

    Science.gov (United States)

    Distelhorst, Laura; Bieda, Amy; DiMarco, Marguerite; Tullai-McGuinness, Susan

    Chemical flame retardants are routinely applied to children's products and are harmful to their health. Pediatric nurses are in a key position to provide education to caregivers on methods to decrease their children's exposure to these harmful chemicals. However, a critical barrier is the absence of any program to educate nurses about chemical flame retardants. In order to overcome this barrier, we must first assess their knowledge. This article provides key highlights every pediatric nurse should know about chemical flame retardants and reports the results of a knowledge assessment study. The purpose of this study was to (1) assess pediatric nurses' knowledge of chemical flame retardants, (2) determine what topic areas of chemical flame retardants pediatric nurses lack knowledge in, and (3) determine the best method to educate nurses about chemical flame retardants. A single sample cross-sectional questionnaire design was used. A total sample of 417 advanced practice registered nurses and registered nurses completed an online survey about chemical flame retardants. Pediatric nurses' knowledge of chemical flame retardants was low (M=13.4 out of 51). Articles, webinars, and e-mails were the primary preferred methods for education on the subject identified as a result of the survey. Pediatric nurses have a large knowledge deficit related to chemical flame retardants. The data collected from this study will help structure future educational formats for pediatric nurses on chemical flame retardants to increase their knowledge. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Flame Retardation Modification of Paper-Based PVC Wallcoverings

    Directory of Open Access Journals (Sweden)

    Lin Hui

    2016-01-01

    Full Text Available The flame-retarded paper-based polyvinyl chloride (PVC wallcoverings were successfully prepared, using plant fiber paper as base material and adding inorganic flame retardants and flame-retarded plasticizer as additives. Flame retardancy, thermostability, smoke suppression and mechanical properties were tested regarding to the prepared wallcoverings. The results showed that 2ZnO·3B2O3·3.5H2O could improve flame retardancy and thermostability of paper-based PVC wallcoverings; plasticizer tricresyl phosphate increased flame retardancy of the prepared materials auxiliarily. Also, flame-retarded paper-based PVC wallcoverings with higher flame retardancy, smoke suppression and mechanical property was prepared using plant fiber paper with fix quantity of 90 g/m3 as base material, using 2ZnO·3B2O3·3.5H2O as inorganic flame retardant, and using tricresyl phosphate as plasticizer. For the flame-retarded paper-based PVC wallcoverings in this study, the limit oxygen index (LOI reaches 32.3, maximal smoke density is 16.91 %, and the horizontal and longitudinal wet tensile strength reaches 1.38 kN·m−1 and 1.51 kN·m−1 respectively. Meanwhile, its flame retardancy meets the requirements about flame retardancy for material Class B1 listed in Chinese National Standards GB 8624-2012, Classification for burning behavior of building materials and products. This research creates an effective path to prepare paper-based PVC wallcoverings with high flame retardancy.

  1. In-line broadband 270 degrees (3lambda/4) chevron four-reflection wave retarders.

    Science.gov (United States)

    Azzam, R M A; Khanfar, H K

    2008-09-20

    The net differential phase shift Delta(t) introduced between the orthogonal p and s linear polarizations after four successive total internal reflections inside an in-line chevron dual-Fresnel-rhomb retarder is a function of the first internal angle of incidence phi and prism refractive index n. Retardance of 3lambda/4 (i.e., Delta(t)=270 degrees) is achieved with minimum angular sensitivity when phi=45 degrees and n=1.900822. Several optical glasses with this refractive index are identified. For Schott glass SF66 the deviation of Delta(t) from 270 degrees is three octaves (0.5 to 4.5 microm) in the visible, near-, and mid-IR spectral range. Another mid-IR 3lambda/4 retarder uses a Si prism, which is coated by an optically thick silicon oxynitride film of the proper composition, to achieve retardance that differs from 270 degrees by < 0.5 degrees over the 3-5 microm spectral range.

  2. Fire-retardant and fire-barrier poly(vinyl acetate composites for sealant application

    Directory of Open Access Journals (Sweden)

    2010-02-01

    Full Text Available Fire-retardant ceramifying poly(vinyl acetate (PVAc sealants have been prepared. The degradation of PVA was integrated with the action of the fire retardants to reduce flammable gases, produce carbonaceous char and convert the fillers into a self-supporting ceramic barrier. PVA is readily degraded by elimination of acetic acid, yielding a char that provides a transitory phase as the filler particles fuse into a ceramic mass. Acetic acid is eliminated at similar temperature to the release of water from magnesium hydroxide fire-retardant, thereby diluting flammable acetic acid. The residual oxide from the fire-retardant filler and structural filler are fused by a flux, zinc borate. The degradative and ceramifying processes were characterised using thermogravimetry, infrared spectroscopy, scanning electron microscopy and ceramic strength. Thermogravimetry of the composites was compared with additive mass loss curves calculated from the components. Deviations between the experimental and additive curves revealed interactions between the components in the composites. The modulus of the PVAc composites and the strength of their ceramic residues after combustion were determined.

  3. Advances in the study of current-use non-PBDE brominated flame retardants and dechlorane plus in the environment and humans

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The fate of the high production volume,currently in use,and not regulated non-polybrominated diphenyl ether(PBDE) flame retardants,such as tetrabromobisphenol A(TBBPA) ,hexabromocyclododecane(HBCD) and dechlorane plus(DP),and the alternative flame retardants of PBDE,such as BTBPE and DBDPE,in the environment has attracted increasing attention and aroused concern due to the increasing regulation and phasing-out of PBDEs.This paper reviews the distribution,bioaccumulation,human exposure and environmental behavior of those non-PBDE flame retardants in various environmental compartments.The data gaps and needs for future research are discussed.

  4. Analysis of retarding effect on αto γtransformation in Fe-C alloy by addition of dispersed particles

    Institute of Scientific and Technical Information of China (English)

    Liang Chen; Yun Han; Bin Zhou; Jie Gong

    2015-01-01

    The effects of dispersed second phase particles onα-ferrite (α) to austenite (γ) transformation at 1140 K in Fe–C alloy were studied by means of phase field simulation. According to the simulated results, it was found that the particle could retard the migration ofα/γinterface. Importantly, both the morphology of particles and the interfacial energy of particle/matrix (αorγ) interface affect the magnitude of the retarding effect. More specifically, the particles with smaller aspect ratio bring stronger retarding force, and when the interfacial energy of particle/γinterface is larger than that of particle/αinterface, the retarding effect also becomes significant. These phenomena could be explained from the viewpoint of change in the total amount of the interfacial energy of the simulation system.

  5. Structure–property relationships of synthetic organophosphorus flame retardant oligomers by thermal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Zhiman [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Wang, Xin; Tang, Gang; Song, Lei [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Yuen, Richard K.K., E-mail: Richard.Yuen@cityu.edu.hk [USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Department of Building and Construction, City University of Hong Kong, Tat Chee Avenue Kowloon (Hong Kong)

    2013-08-10

    Highlights: • Oligomers with different chemical components in molecular chains were synthesized. • FP-3 containing three IFR components possessed high thermal stability. • FP-3 possessed lowest flammability. • FP-3 exhibited a synergistic interaction between gas and condensed phase. - Abstract: A series of flame retardant oligomers with different chemical components in molecular chains, designated as FP-1, FP-2 and FP-3, respectively, were successfully synthesized using solution polycondensation and well characterized. The thermal properties and flammability of these oligomers were investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The results demonstrated that FP-3 had the lowest flammability in terms of the lowest maximum mass loss rate, and FP-1 possessed the highest thermal stability and char yield, due to its higher stable hexatomic ring structure of piperazine compared with the linear alkane chain structure of neopentyl glycol. The gases evolved during decomposition were analyzed using Fourier transform infrared coupled with the thermogravimetric analyzer (TG–IR) technique. The char residues of the flame retardant oligomers were investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results demonstrated that FP-3 exhibited a synergistic interaction between the gas phase and condensation phase, increasing its flame retardancy.

  6. The research of far infrared flame retardant polyester staple fiber

    Science.gov (United States)

    Li, Qingshan; Zhang, Kaijun; Luo, Jinqong; Li, Ji’an; Jiang, Jian; Liang, Qianqian; Jin, Yongxia; Liu, Bing

    2017-01-01

    Far infrared flame retardant slices was prepared, fiber with far infrared flame retardant composite function was also prepared by the method of melt spinning. Scanning electron microscopy (SEM) was used to observe the fibrous microscopic structure. In the SEM images, functional ultrafine powder particle size and distribution in the fiber were visible. The results show that the functional ultrafine powder is evenly distributed on the fibrous surface, which is closely combined with fiber, and the far infrared emissivity is F, which is more than (8 to 14 microns) 0.88. Far infrared flame retardant polyester fiber has not only good flame retardant, but also environmental health effect: releasing negative ions and launch far-infrared, which shows wide application prospect. The fiber was processed into far-infrared flame retardant electric blanket, whose functional indicators and flame retardant properties are not reduced.

  7. Factors affecting social integration of noninstitutionalized mentally retarded adults.

    Science.gov (United States)

    Reiter, S; Levi, A M

    1980-07-01

    The social integration of noninstitutionalized moderately and mildly mentally retarded young adults was investigated. A group of moderately and mildly retarded adults (study group) was compared with a group of borderline retarded (control group) adults on employability, behavior at work, social integration and social skills, personality, and self-concept. Findings indicated that the study group was less well integrated at work and in society than was the control group and showed lack of social skills. The retarded adults who had nonretarded friends showed better social-educational skills than did the other subjects. Findings suggest that even retarded individuals who grow up in the community need help in order to become socially independent. The existence of a special social club for retarded adults was found to fulfill the functions of a sheltered framework. Participants in the club showed more positive self-concepts; however, the club did not seem to prepare them for social integration in the general community.

  8. Nanotechnology finding its way into flame retardancy

    Energy Technology Data Exchange (ETDEWEB)

    Schartel, Bernhard, E-mail: bernhard.schartel@bam.de [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2014-05-15

    Nanotechnology is one of the key technologies of the 21{sup st} century. The exploitation of 'new' effects that arise from materials structured on the nano-scale has also been proposed successfully for flame retardancy of polymers since the end of the 90s. Of all of the approaches these include, at this time the use of nanocomposites offers the best potential for industrial application, also some other ideas are sketched, such as using electrospun nanofibers mats or layer-by-layer deposits as protection coatings, as well as sub-micrometer multilayer coatings as effective IR-mirrors. The general phenomena, inducing a flow limit in the pyrolysing melt and changing the fire residue, are identified in nanocomposites. Key experiments are performed such as quasi online investigation of the protection layer formation to understand what is going on in detail. The flame retardancy mechanisms are discussed and their impact on fire behaviour quantified. With the latter, the presentation pushes forward the state of the art. For instance, the heat shielding is experimentally quantified for a layered silicate epoxy resin nanocomposite proving that it is the only import mechanism controlling the reduction in peak heat release rate in the investigated system for different irradiations. The flame retardancy performance is assessed comprehensively illuminating not only the strengths but also the weak points of the concepts. Guidelines for materials development are deduced and discussed. Apart from inorganic fillers (layered silicate, boehmite, etc.) not only carbon nanoobjects such as multiwall carbon nanotubes, multilayer graphene and graphene are investigated, but also nanoparticles that are more reactive and harbor the potential for more beneficial interactions with the polymer matrix.

  9. Retardo del crecimiento intrauterino Intrauterine growth retardation

    Directory of Open Access Journals (Sweden)

    Adriana Cuartas Calle

    1995-01-01

    Full Text Available

    El crecimiento fetal anormal es un aspecto de gran interés en la obstetricia actual y un dilema clínico relativamente frecuente. La falla del crecimiento sigue siendo un enigma a pesar de los adelantos que ha habido en su conocimiento: el diagnóstico temprano y preciso del retardo del crecimiento puede aminorar la incidencia de complicaciones y muerte en fetos con este problema. Por ello es necesario mejorar las técnicas para identificar esta entidad y asegurar una atención apropiada durante el embarazo y el parto. En este artículo se resumen datos acerca de la definición del retardo del crecimiento fetal, su fisiopatología, clasificación, etiología, diagnóstico y manejo.

    Abnormal fetal growth is a very important aspect In present-day obstetrics and a frequent clinical dilemma. Fetal failure to grow continues to be puzzling, despite advances in its knowledge; early and precise diagnosis of growth retardation can diminish the incidence of complications and death of fetuses with this problem. It becomes therefore necessary, in the presence of growth retardation, to improve diagnostic techniques and assure proper attention during pregnancy and delivery. Information is summarized in this review on the definition, pathophysiology, classification, etiology, diagnosis and handling of fetal growth retardation.

  10. Our Sedation Experience on Mentally Retarded Patients

    Directory of Open Access Journals (Sweden)

    Metin Alkan

    2014-03-01

    Full Text Available Aim: The majority of dental treatments can be performed under local anesthesia. However, sedation or general anesthesia are often required for mentally retarded patients presenting a lack of cooperation. The aim of this study was to retrospectively evaluate the outcomes of mentally retarded patients treated under sedation. Material and Method: The records of the 214 mentally retarded patients that were treated under sedation between 2010-2012 were retrospectively evaluated. The retrospective data included demographic variables, duriation of anesthesia, anti-epileptic drugs used, level of sedation, anesthetic agents, the type of dental treatment and adverse events during and after sedation. Results: In this study the mean age of patients was 22,49±9,54. The female/male ratio was 109/105. The number of ASA I, II, III patients were 43, 157 and 14 respectively. 16.8% of the patiens (n=36 was on one anti-epileptic drug regimen, while 29.9% of the patiens (n=54 was on more than one anti-epileptic drug regimen. The sedation levels were determined as minimal sedation (6.5%, n=14, moderate sedation (35%, n=75 and deep sedation (58.4%, n=125 respectively. The midazolam-ketamine combination was the most preferred anesthetic regimen (41.1%, n=88. Single dental extraction was the most performed dental treatment (58.4%, n=125. Postoperative nausea and vomiting was encountered in 3.7% of patients (n=8. Respiratuar depression occurred in 2 patients. Two patients developed bronchospasm, while one patient developed postoperative agitation, deep bradycardia and allergic reaction respectively. Discussion: We are of the opinion that sedation can be performed safely by choosing the appropriate drug and method without depressing respiration and reflexes.

  11. Highly porous flame-retardant and sustainable biofoams based on wheat gluten and in situ polymerized silica

    DEFF Research Database (Denmark)

    Wu, Qiong; Andersson, Richard L.; Holgate, Tim

    2014-01-01

    This article presents a novel type of flame-retardant biohybrid foam with good insulation properties based on wheat gluten and silica, the latter polymerized in situ from hydrolysed tetraethyl orthosilicate (TEOS). This led to the formation of intimately mixed wheat gluten and silica phases, where...

  12. [Negative destructive behavior in young retarded children].

    Science.gov (United States)

    Dosen, A

    1983-02-01

    Twenty percent of a population of mentally retarded children, who underwent clinical observation because of behavior problems, demonstrated serious aggressive, destructive, negativistic and hyperactive behavior patterns. According to the parents this type of behavior developed between two and four years of age. It remains unclear whether this behavior is caused by a differential rate of maturation of certain brain structures or by unfavorable emotional and environmental variables. A psychotherapeutic approach to the treatment of these children led to positive results. It is supposed that if left untreated, a symptom shift can occur towards neurotic, depressive or aggressive behavior when the child gets older.

  13. Tactile function of educable mentally retarded children.

    Science.gov (United States)

    McCracken, A

    1975-08-01

    The tactile perception ability of 29 seven-and eight-year-old educable mentally retarded children was evaluated by using the tactile perception portions of the Southern California Sensory Integration Tests. The children were also observed for tactile defensive behavior. Compared to normal children of the same age (as reported in normative data), this sample of children was significantly inferior in manual form, finger identification, graphesthesia, and perception of simultaneous stimuli, but not in the localization of single stimuli. During the testing, 62 percent showed tactile defensive behavior. The role of tactile perception in the development of symbolic communications is reviewed.

  14. Aspects of Verbal Behavior Cited by Listeners in Judging Speakers as Retarded or Not Retarded.

    Science.gov (United States)

    Kernan, Keith T.; And Others

    1986-01-01

    Results of asking 30 nonprofessionals for reasons speakers were judged to be retarded or not indicated that quality of speech (articulation, prosody, etc.) and the structure, content, and coherence of discourse are more important than sentence-level grammatical features in forming impressions of cognitive competence. (Author/DB)

  15. Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients.

    NARCIS (Netherlands)

    Buggenhout, G.J.C.M. van; Ravenswaaij-Arts, C.M.A. van; Mieloo, H.; Syrrou, M.; Hamel, B.C.J.; Brunner, H.G.; Fryns, J.P.

    2001-01-01

    In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysmorphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectabl

  16. Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients.

    NARCIS (Netherlands)

    Buggenhout, G.J.C.M. van; Ravenswaaij-Arts, C.M.A. van; Mieloo, H.; Syrrou, M.; Hamel, B.C.J.; Brunner, H.G.; Fryns, J.P.

    2001-01-01

    In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysmorphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectabl

  17. Research on Alkaline Filler Flame-Retarded Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    HU Shuguang; ZHANG Houji; WANG Jiaolan

    2006-01-01

    Used as flame retardant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame-retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel pavement.

  18. MENTALLY RETARDED CHILD AT PRESCHOOL AGE AND FAMILY

    Directory of Open Access Journals (Sweden)

    M. BOSKOVSKA

    1998-09-01

    Full Text Available The authors’ in their exposure likes to point the most complicated problems, which appeared when the mentally retarded child was born in a family that is followed by dramatic changes of their wishes and aspirations. In this contexts the authors elaborated many questions as well as:· relation between the parents;· mentally retarded child in the setting and living ambient;· social problems of mentally retarded children and their families;· the rule of the treats in the work with parents of mentally retarded child.

  19. Bender-Gestalt reproduction times for retarded adults.

    Science.gov (United States)

    Andert, J N; Hustak, T L; Dinning, W D

    1978-10-01

    Examined the length of time required by retarded adults to complete the Bender-Gestalt test with a sample of 241 test administrations. In order to provide for normative comparisons among retarded adults, descriptive data are presented on the Bender reproduction times of adults in three AAMD ranges of retardation based on WAIS IQs and two ranges based on Stanford-Binet IQs. Negative correlations were found between the length of Bender times and the degree of retardation. The duration of Bender times was correlated positively with the number of errors in reproduction as measured by the Koppitz developmental scoring system.

  20. Mental Retardation (MR Etiology in Children Referred to Care Services

    Directory of Open Access Journals (Sweden)

    Mahdi Foroutan

    2014-10-01

    Conclusion: Considering Mental Retardation (MR financial burden, planning to reduce and control preventable factors such as parents’ drug abuse could be possible through education and cultural changes.

  1. POLYAMIDE 6 WITH A FLAME RETARDANT ENCAPSULATED BY POLYAMIDE 66: FLAME RETARDATION, THERMO-DECOMPOSITION AND THE POTENTIAL MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Wei-cheng Xiong; Li Chen; Bin Zhao; De-yi Wang; Yu-zhong Wang

    2012-01-01

    A novel encapsulated flame retardant containing phosphorus-nitrogen (MSMM-Al-P) was prepared by encapsulating with polyamide 66 (PA66-MSMM-Al-P) for the flame retardation of polyamide 6 (PA6).The structure and thermal properties of PA66-MSMM-Al-P were characterized by Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy and thermogravimetric analysis.The flammability of PA6 containing' flame retardants (MSMMAl-P and PA66-MSMM-Al-P) was investigated by the limiting oxygen index test,vertical burning test and cone calorimeter.The flame retardancy and cone calorimetric analyses suggested a synergistic effect between PA66 and MSMM-Al-P in the flame-retardant PA6.Thermal stability of the flame-retardant PA6 was also investigated.

  2. Fire-retardant coatings based on organic bromine/phenoxy or brominated epoxy systems

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M.; Chiu, Ing L.

    1989-06-01

    Thin phenoxy and brominated epoxy/curing agent films were prepared by solvent casting on Mylar and Kapton. Thicknesses were approximated assuming volume additivity. Important parameters were uniformity of thickness, distribution of the bromine-containing fire retardant, adhesion to carrier substrate (either Mylar or Kapton), and uniformity of the coating, i.e., absence of pinholes, blush, blistering, etc. Wetting behavior was modified using fluoro, silicone or polyurea surfactants. Several solvent systems were examined and a ternary solvent system was ultimately used. Distribution of fire-retardant bromine was analyzed using electron microprobe, x-ray fluorescence and wet chemical methods. Significant discrepancies in the /mu/m-scale analyses of the microprobe measurements have not been resolved. Some of the brominated fire retardants were insoluble in the resin systems and the phase separation was immediately obvious. Similarly, some of the crystallizable epoxies could not be cast easily into homogeneous, amorphous films. Castings were made on a standard 8'' /times/ 10'' aluminum vacuum plate polished with jeweler's rouge prior to every casting. Solvent was removed in a forced air or vacuum oven. Removal and/or curing was accelerated with temperature. The fire-retardant bromine was required to be stable in alcohol/salt solutions. Final formulation used after a significant amount of testing was phenoxy resin PKHC in a ternary solvent system composed of methylethyl ketone, cellosolve acetate and toluene. Tetrabromobisphenol A was used as the flame retardant with FC-430 as surfactant. The dying schedule was 30 minutes at 150/degree/C. 4 refs., 6 figs., 3 tabs.

  3. Detection of 34 plasticizers and 25 flame retardants in indoor air from houses in Sapporo, Japan.

    Science.gov (United States)

    Takeuchi, Shinji; Kojima, Hiroyuki; Saito, Ikue; Jin, Kazuo; Kobayashi, Satoshi; Tanaka-Kagawa, Toshiko; Jinno, Hideto

    2014-09-01

    Various plasticizers and flame retardants are contained in building materials and furniture produced for indoor environments. However, some of these material inclusions have been reported to cause endocrine-disrupting and mucosa-irritating effects. Because of the local climate, buildings in Sapporo are better insulated against cold weather than those in many other areas in Japan. In this study, we measured 59 compounds, including plasticizers (phthalates, adipates, and others) and flame retardants (organo-phosphates and brominated compounds), from indoor air samples from six houses in Sapporo. These compounds were measured separately in the gas phase and the particle phase using a two-stage cartridge equipped with a quartz fiber filter (1 μm mesh) and C18 solid-phase extraction disk for sampling and analyzed by GC/MS and LC/MS/MS (for the detection of brominated flame retardants). Among the 59 compounds measured in this study, 34 compounds were detected from the indoor air of the six houses. The highest concentration among the 34 compounds found in a newly built house was 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TXIB) at 20.8 μg/m(3). Di(2-ethyl-1-hexyl)terephthalate (DEHT), which has been used in recent years as an alternative to di(2-ethyl-1-hexyl)phthalate (DEHP), was found in all six houses, although at low concentrations ranging from 0.005 to 0.027 μg/m(3). To our knowledge, this is the first report of DEHT in indoor air in Japan. Among the compounds detected in this study, those with lower molecular weights tended to be captured in the C18 solid-phase extraction disk rather than in the quartz fiber filter. These results suggest that compounds with higher volatility exist preferentially in the gas phase, whereas compounds with lower volatility exist preferentially in the particulate phase in indoor air.

  4. A nonvocal system for teaching retarded children to read and write.

    Science.gov (United States)

    Kuntz, J B; Carrier, J K; Hollis, J H

    1978-01-01

    This study investigated the development of nonvocal teaching of reading and writing in severely retarded children. Fourteen subjects were selected who demonstrated limited communication skills, and were randomly placed into two groups. Group A received training procedures utilizing abstract plastic symbols which were arbitrarily assigned to represent specific words. The training program was divided into three phases. Phase I consisted of training left to right sequencing of four color--coded forms; Phase II consisted of training of matching symbols to stimulus pictures; and Phase III consisted of training of fading from symbols to printed words. The subjects completing this training program demonstrated the ability to learn selected reading and writing skills, i.e., they learned to sequence an article, subject noun, auxiliary verb, and verb. They also demonstrated functional semantic comprehension of five nouns and five verbs. Thirteen subjects finished the communication training program in less than four months with a mean training of 7 hours and 55 minutes. This is approximately 2 hours of training a month per subject to learn these skills. The data showed that Group B (rebuses) required fewer trials than Group A (abstract symbols) to meet criterion for Phase II, matching symbols to stimulus pictures. This suggests that Group B subjects may have had a meaningful association for the rebus signs which generalized to stimulus pictures. Group A (abstract symbols) required fewer trials than Group B (rebuse) to meet criterion for Phase 111, matching printed words to stimulus pictures. This indicates that perhaps Group A's training with abstract symbols positively affected learning to read printed words. The success of the visual nonvocal treatment program with the severely retarded is encouraging. Indeed, this is a different and viable approach in teaching communication skills (reading and writing) to the retarded.

  5. Mental Retardation. Fact Sheet = El Retraso Mental. Hojas Informativas Sobre Discapacidades.

    Science.gov (United States)

    National Information Center for Children and Youth with Disabilities, Washington, DC.

    This fact sheet on mental retardation is written in both English and Spanish. It begins with a vignette of a 15-year-old boy with mental retardation. Mental retardation is briefly explained as are some causes of mental retardation. It notes that a diagnosis of mental retardation looks at two things: first, the ability of a person's brain to learn,…

  6. Monte Carlo-based assessment of the trade-off between spatial resolution, field-of-view and scattered radiation in the variable resolution X-ray CT scanner

    NARCIS (Netherlands)

    Arabi, Hossein; Asl, Ali Reza Kamali; Ay, Mohammad Reza; Zaidi, Habib

    Objective: The purpose of this work is to evaluate the impact of optimization of magnification on performance parameters of the variable resolution X-ray (VRX) CT scanner. MethodsA realistic model based on an actual VRX CT scanner was implemented in the GATE Monte Carlo simulation platform. To

  7. Feasibility of Diagrammatic Monte-Carlo based on weak-coupling expansion in asymptotically free theories: case study of $O(N)$ sigma-model in the large-$N$ limit

    CERN Document Server

    Buividovich, P V

    2015-01-01

    We discuss the feasibility of applying Diagrammatic Monte-Carlo algorithms to the weak-coupling expansions of asymptotically free quantum field theories, taking the large-$N$ limit of the $O(N)$ sigma-model as the simplest example where exact results are available. We use stereographic mapping from the sphere to the real plane to set up the perturbation theory, which results in a small bare mass term proportional to the coupling $\\lambda$. Counting the powers of coupling associated with higher-order interaction vertices, we arrive at the double-series representation for the dynamically generated mass gap in powers of both $\\lambda$ and $\\log(\\lambda)$, which converges quite quickly to the exact non-perturbative answer. We also demonstrate that it is feasible to obtain the coefficients of these double series by a Monte-Carlo sampling in the space of Feynman diagrams. In particular, the sign problem of such sampling becomes milder at small $\\lambda$, that is, close to the continuum limit.

  8. A comparative study on the risk of second primary cancers in out-of-field organs associated with radiotherapy of localized prostate carcinoma using Monte Carlo-based accelerator and patient models

    Energy Technology Data Exchange (ETDEWEB)

    Bednarz, Bryan; Athar, Basit; Xu, X. George [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02108 and Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2010-05-15

    Purpose: A physician's decision regarding an ideal treatment approach (i.e., radiation, surgery, and/or hormonal) for prostate carcinoma is traditionally based on a variety of metrics. One of these metrics is the risk of radiation-induced second primary cancer following radiation treatments. The aim of this study was to investigate the significance of second cancer risks in out-of-field organs from 3D-CRT and IMRT treatments of prostate carcinoma compared to baseline cancer risks in these organs. Methods: Monte Carlo simulations were performed using a detailed medical linear accelerator model and an anatomically realistic adult male whole-body phantom. A four-field box treatment, a four-field box treatment plus a six-field boost, and a seven-field IMRT treatment were simulated. Using BEIR VII risk models, the age-dependent lifetime attributable risks to various organs outside the primary beam with a known predilection for cancer were calculated using organ-averaged equivalent doses. Results: The four-field box treatment had the lowest treatment-related second primary cancer risks to organs outside the primary beam ranging from 7.3x10{sup -9} to 2.54x10{sup -5}%/MU depending on the patients age at exposure and second primary cancer site. The risks to organs outside the primary beam from the four-field box and six-field boost and the seven-field IMRT were nearly equivalent. The risks from the four-field box and six-field boost ranged from 1.39x10{sup -8} to 1.80x10{sup -5}%/MU, and from the seven-field IMRT ranged from 1.60x10{sup -9} to 1.35x10{sup -5}%/MU. The second cancer risks in all organs considered from each plan were below the baseline risks. Conclusions: The treatment-related second cancer risks in organs outside the primary beam due to 3D-CRT and IMRT is small. New risk assessment techniques need to be investigated to address the concern of radiation-induced second cancers from prostate treatments, particularly focusing on risks to organs inside the primary beam.

  9. A comparative study on the risk of second primary cancers in out-of-field organs associated with radiotherapy of localized prostate carcinoma using Monte Carlo-based accelerator and patient models

    Science.gov (United States)

    Bednarz, Bryan; Athar, Basit; Xu, X. George

    2010-01-01

    Purpose: A physician’s decision regarding an ideal treatment approach (i.e., radiation, surgery, and∕or hormonal) for prostate carcinoma is traditionally based on a variety of metrics. One of these metrics is the risk of radiation-induced second primary cancer following radiation treatments. The aim of this study was to investigate the significance of second cancer risks in out-of-field organs from 3D-CRT and IMRT treatments of prostate carcinoma compared to baseline cancer risks in these organs. Methods: Monte Carlo simulations were performed using a detailed medical linear accelerator model and an anatomically realistic adult male whole-body phantom. A four-field box treatment, a four-field box treatment plus a six-field boost, and a seven-field IMRT treatment were simulated. Using BEIR VII risk models, the age-dependent lifetime attributable risks to various organs outside the primary beam with a known predilection for cancer were calculated using organ-averaged equivalent doses. Results: The four-field box treatment had the lowest treatment-related second primary cancer risks to organs outside the primary beam ranging from 7.3×10−9 to 2.54×10−5%∕MU depending on the patients age at exposure and second primary cancer site. The risks to organs outside the primary beam from the four-field box and six-field boost and the seven-field IMRT were nearly equivalent. The risks from the four-field box and six-field boost ranged from 1.39×10−8 to 1.80×10−5%∕MU, and from the seven-field IMRT ranged from 1.60×10−9 to 1.35×10−5%∕MU. The second cancer risks in all organs considered from each plan were below the baseline risks. Conclusions: The treatment-related second cancer risks in organs outside the primary beam due to 3D-CRT and IMRT is small. New risk assessment techniques need to be investigated to address the concern of radiation-induced second cancers from prostate treatments, particularly focusing on risks to organs inside the primary beam. PMID:20527532

  10. Monte Carlo-based assessment of the trade-off between spatial resolution, field-of-view and scattered radiation in the variable resolution X-ray CT scanner

    NARCIS (Netherlands)

    Arabi, Hossein; Asl, Ali Reza Kamali; Ay, Mohammad Reza; Zaidi, Habib

    2015-01-01

    Objective: The purpose of this work is to evaluate the impact of optimization of magnification on performance parameters of the variable resolution X-ray (VRX) CT scanner. MethodsA realistic model based on an actual VRX CT scanner was implemented in the GATE Monte Carlo simulation platform. To evalu

  11. GZP型60Co源剂量学参数的蒙特卡洛模拟%A Monte Carlo-based dosimetric study of the GZP 60Co source

    Institute of Scientific and Technical Information of China (English)

    王先良; 袁珂; 唐斌; 康盛伟; 黎杰; 肖明勇; 李晓兰; 李林涛; 王培

    2016-01-01

    目的 GZP型60Co源高剂量率后装机在临床中已有应用,模拟计算GZP型60Co源的剂量学参数.方法 使用EGSnrc蒙特卡洛软件模拟计算已知的BEBIG60Co源(Co0.A86)剂量学参数,与其结果进行对比,验证方法的可行性.对GZP型高剂量率后装机60Co源进行建模,用同样方法模拟计算GZP型60Co源剂量学参数.结果 对BEBIG 60Co源,结果与标准数据吻合很好,单位活度空气比释动能强度SK/A相差0.2%,剂量率常数∧相差1.0%,径向剂量函数gL(r)和各向异性函数F(r,θ)曲线吻合.计算得到的GZP型60Co源(1、2)号通道的SK/A和∧分别是3.011×10-7 cGycm2h-1Bq-1和1.118 cGyh-1U-1,GZP (3)号通道60Co源的SK/A和∧分别是3.002× 10-7 cGycm2h-1Bq-1和1.110 cGyh-1U-1,gL(r)、F(r,θ)和水模中单位空气比释动能强度的剂量率参照AAPM推荐列出.结论 研究结果可用于GZP型60Co源的计划系统中,也可以作为GZP型60Co源的质量控制.%Objective To simulate and calculate the dosimetric parameters of the GZP 60Co source that has been clinically used in high-dose-rate brachytherapy.Methods The EGSnrc Monte Carlo software was used to simulate and calculate the dosimetric parameters of a well known BEBIG 60Co source (Co0.A86).The results were compared with the actual parameters to verify the feasibility of this method.A Monte Carlo model of the GZP 60Co source for high-dose-rate brachytherapy was established to simulate and calculate its dosimetric parameters in the same way.Results For the BEBIG 60Co source,the resuhs were well accorded with the standard.The air-kerma strength per unit activity (SK/A) and dose rate constant (∧)deviated from the standard by 0.2% and 1.0%,respectively.The curves of the radial dose function gL(r) and the anisotropy function F (r,θ) fit well.For the GZP 60Co source,the SK/A and ∧values were calculated as 3.011 × 10-7 cGycm2h-1Bq-1 and 1.118 cGyh-1 U-1 in channel l&2 and 3.002× 10-7 cGycm2h-1 Bq-1 and 1.110 cGyh-1U-1 in channel 3.The gL(r),F (r,θ),and dose rate per unit air-kerma strength in a liquid water phantom were listed as the American Association of Physicists in Medicine recommended.Conclusions The results can be used in planning system and quality control for the GZP 60Co source.

  12. Flame Retardancy of PA6 Using a Guanidine Sulfamate/Melamine Polyphosphate Mixture

    Directory of Open Access Journals (Sweden)

    Mathieu Coquelle

    2015-02-01

    Full Text Available Polyamide 6 (PA6 is a widely-used polymer that could find applications in various sectors, including home textiles, transportation or construction. However, due to its organic nature, PA6 is flammable, and flame-retardant formulations have to be developed to comply with fire safety standards. Recently, it was proposed to use ammonium sulfamate as an effective flame retardant for PA6, even at low loading content. However, processing issues could occur with this additive considering large-scale production. This paper thus studies the use of another sulfamate salt—guanidine sulfamate (GAS—and evidences its high efficiency when combined with melamine polyphosphate (MPP as a flame retardant for PA6. A decrease of the peak of the heat release rate by 30% compared to pure PA6 was obtained using only 5 wt% of a GAS/MPP mixture in a microscale calorimeter. Moreover, PA6 containing the mixture GAS/MPP exhibits a Limiting Oxygen Index (LOI of 37 vol% and is rated V0 for the UL 94 test (Vertical Burning Test; ASTM D 3801. The mechanisms of degradation were investigated analyzing the gas phase and solid phase when the material degrades. It was proposed that MPP and GAS modify the degradation pathway of PA6, leading to the formation of nitrile end-group-containing molecules. Moreover, the formation of a polyaromatic structure by the reaction of MPP and PA6 was also shown.

  13. Retrospective analysis of "new" flame retardants in the global atmosphere under the GAPS Network.

    Science.gov (United States)

    Lee, Sum Chi; Sverko, Ed; Harner, Tom; Pozo, Karla; Barresi, Enzo; Schachtschneider, JoAnne; Zaruk, Donna; DeJong, Maryl; Narayan, Julie

    2016-10-01

    A retrospective analysis was conducted on air samples that were collected in 2005 under the Global Atmospheric Passive Sampling (GAPS) Network around the time period when the Stockholm Convention on Persistent Organic Pollutants came into force. Results are presented for several new flame retardants, including hexabromocyclododecane (HBCD), which was recently listed under the Convention (2013). These results represent the first global-scale distributions in air for these compounds. The targeted compounds are shown to have unique global distributions in air, which highlights the challenges in understanding the sources and environmental fate of each chemical, and ultimately in their assessments as persistent organic pollutants. The study also demonstrates the feasibility of using the PUF disk passive air sampler to study these new flame retardants in air, many of which exist entirely in the particle-phase as demonstrated in this study using a KOA-based partitioning model.

  14. STUDY ON THE EFFECTS OF TLCP ON PYROLYSIS OF PET AND ITS RETARDANT MECHANISM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The flame retardancy of aromatic thermotropic liquid crystal phosphorus-containing copolyester,TLCP,on PET was investigated.The results show that the presence of TLCP promotes char formation of the substrate and enhances thermal stability of char,hence delay its decomposition.SEM pictures show that the char formed from PET/TLCP is more compact,therefore is more resistant to fire and heat than that from pure PET.Evolved gas analysis by I.R measurements indicates that TLCP would decompose to produce phosphorus containing small molecular compounds in pyrolysis process.Phosphoruscontaining volatile compounds are detected in gas pyrolytical products.It is suggested that TLCP could play an important role of flame retardancy in vapor phase.TLCP could inhibit the generation of combustible volatile in the pyrolytical process of PET,and therefore prevent the fire propagation during the combustion since combustible volatile is necessary for the generation of fire.

  15. Flame Retardance and Physical Properties of Novel Cured Blends of Unsaturated Polyester and Furan Resins

    Directory of Open Access Journals (Sweden)

    Baljinder Kaur Kandola

    2015-02-01

    Full Text Available Novel blends of two furan resins with an unsaturated polyester have been prepared and cured by parallel free radical (for the unsaturated polyester and acid-catalysed crosslinking (for the furan resin to give co-cured composite materials. Although these materials have inferior physical properties, such as low Tg and low storage modulus compared with those of unsaturated polyester and furan resins alone, they show markedly improved flame retardance compared with that of the normally highly flammable unsaturated polyester. This increased flame retardance arises from a condensed phase mechanism in which the furanic component forms a semi-protective char, reducing rates of thermal degradation and total heat release and heat of combustion. The blends also burn with reduced smoke output compared with that from unsaturated polyester alone.

  16. Building America Top Innovations 2012: Vapor Retarder Classification

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2013-01-01

    This Building America Top Innovations profile describes research in vapor retarders. Since 2006 the IRC has permitted Class III vapor retarders like latex paint (see list above) in all climate zones under certain conditions thanks to research by Building America teams.

  17. Perceptual-Motor Attributes of Mentally Retarded Youth.

    Science.gov (United States)

    Cratty, Bryant J.

    To evaluate six perceptual-motor attributes of trainable and educable mentally retarded children, a battery of tests was constructed which included body perception, gross agility, balance, locomotor ability, throwing, and tracking; 83 retarded subjects provided reliability data, and their scores, with those of 120 additional subjects, provided…

  18. Community Care for People with Mental Retardation in the Netherlands.

    Science.gov (United States)

    Dosen, Anton

    1988-01-01

    Services for people with mental retardation in the Netherlands are examined, with emphasis on normalization, placement options including group homes and institutionalization, guidance for families through the Social Pedological Service, and the care of mental illness in mentally retarded persons through special diagnostic and treatment centers.…

  19. Kansas Citizens Plan Comprehensive Mental Retardation Services. Summary and Recommendations.

    Science.gov (United States)

    Kansas State Dept. of Social Welfare, Topeka. Div. of Institutional Management.

    Summarized are the recommendations and findings of 1 1/2-year project to prepare a plan to combat mental retardation in Kansas. The study is said to have been based on the principle that needs rather than diagnostic labels should determine services provided. Outlined are mental retardation planning activities at the federal level and preplanning…

  20. Toxicity of new generation flame retardants to Daphnia magna

    NARCIS (Netherlands)

    Waaijers, S.L.; Hartmann, J; Soeter, A.M.; Helmus, R.; Kools, S.A.E.; de Voogt, P.; Admiraal, W.; Parsons, J.R.; Kraak, M.H.S.

    2013-01-01

    There is a tendency to substitute frequently used, but relatively hazardous brominated flame retardants (BFRs) with halogen-free flame retardants (HFFRs). Consequently, information on the persistence, bioaccumulation and toxicity (PBT) of these HFFRs is urgently needed, but large data gaps and

  1. Newborn Screening To Prevent Mental Retardation. The Arc Q & A.

    Science.gov (United States)

    Arc, Arlington, TX.

    This information fact sheet on screening newborns to prevent mental retardation defines newborn screening and outlines how screening is performed. It discusses the six most common disorders resulting in mental retardation for which states most commonly screen. These include phenylketonuria, congenital hypothyroidism, galactosemia, maple syrup…

  2. Fire Retardant Textiles: A Particular Reference to China and Kenya

    Institute of Scientific and Technical Information of China (English)

    Eric Oyondi Nganyi; YU Chong-wen

    2002-01-01

    As more and more attention is paid to the utilization of fire retardant textile products in apparel, household,furnishing, and industrial sectors, this paper presents a brief survey of the use of fire retardant (FR) textile products, the rules, and regulations concerning their use, and their market potential in China and in Kenya.

  3. Psychopharmacology and Mental Retardation: A 10 Year Review (1990- 1999).

    Science.gov (United States)

    Matson, Johnny L.; Bamburg, Jay W.; Mayville, Erik A.; Pinkston, Jim; Bielecki, Joanne; Kuhn, David; Smalls, Yemonja; Logan, James R.

    2000-01-01

    Review of the literature on psychopharmacology and mental retardation from 1990-1999 found most studies had major methodological flaws. Also, most drug administrations were not based in science, were not evaluated appropriately, and generally did not follow best practices for treatment of persons with mental retardation. A table lists the studies…

  4. Lessons from the Margins, Narrating Mental Retardation: A Review Essay.

    Science.gov (United States)

    Biklen, Douglas

    2000-01-01

    This essay argues that ideas circulated by Blatt and Dybwad, two scholars who exposed the plight of people labeled "retarded," can be illustrated in certain inclusive education practices and reinforced and refined in various critical narratives about mental retardation, particularly in autobiographical accounts of people with…

  5. Carbamazepine-Induced Hyponatremia in Patients with Mental Retardation.

    Science.gov (United States)

    Kastner, Ted; And Others

    1992-01-01

    This study of 40 patients with mental retardation receiving carbamazepine found hyponatremia in only 5 percent of these patients and found a statistically, but not clinically, significant decrease in serum sodium levels in patients receiving anticonvulsant polytherapy. Results support the use of this drug with patients with mental retardation and…

  6. 38 CFR 4.127 - Mental retardation and personality disorders.

    Science.gov (United States)

    2010-07-01

    ... personality disorders. 4.127 Section 4.127 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS... and personality disorders. Mental retardation and personality disorders are not diseases or injuries... superimposed upon mental retardation or a personality disorder may be service-connected. (Authority: 38 U.S.C...

  7. Muscle Fatigue during Intermittent Exercise in Individuals with Mental Retardation

    Science.gov (United States)

    Zafeiridis, Andreas; Giagazoglou, Paraskevi; Dipla, Konstantina; Salonikidis, Konstantinos; Karra, Chrisanthi; Kellis, Eleftherios

    2010-01-01

    This study examined fatigue profile during intermittent exercise in 10 men with mild to moderate mental retardation (MR) and 10 men without mental retardation (C). They performed 4 x 30 s maximal knee extensions and flexions with 1-min rest on an isokinetic dynamometer. Peak torque of flexors (PTFL) and extensors (PTEX), total work (TW), and…

  8. Three-dimensional polarization ray-tracing calculus II: retardance.

    Science.gov (United States)

    Yun, Garam; McClain, Stephen C; Chipman, Russell A

    2011-06-20

    The concept of retardance is critically analyzed for ray paths through optical systems described by a three-by-three polarization ray-tracing matrix. Algorithms are presented to separate the effects of retardance from geometric transformations. The geometric transformation described by a "parallel transport matrix" characterizes nonpolarizing propagation through an optical system, and also provides a proper relationship between sets of local coordinates along the ray path. The proper retardance is calculated by removing this geometric transformation from the three-by-three polarization ray-tracing matrix. Two rays with different ray paths through an optical system can have the same polarization ray-tracing matrix but different retardances. The retardance and diattenuation of an aluminum-coated three fold-mirror system are analyzed as an example.

  9. Studies on Flame Retardants on Malaysian Coir Fiber

    Directory of Open Access Journals (Sweden)

    Elwaleed Awad Khidir

    2011-01-01

    Full Text Available In this study to the effect of the utilization of urea and diammonium phosphate as fire retardant on Malaysian coir fiber was evaluated. Flammability and thermogravimetric analysis (TGA tests were used to evaluate the fire retardancy. Weight loss and percentage of mass residue were used as a measure from the results of flammability and TGA, respectively. The results revealed the effectiveness of using urea and diammonium phosphate as fire retardant for Malaysian coir fiber. However, for the samples treated with retardant high concentration the weight loss is not significant with the time of dipping treatment. This indicates that the just dip application for the fire retardant of higher concentration is sufficient.

  10. Human placental lactogen and intrauterine growth retardation.

    Science.gov (United States)

    Spellacy, W N; Buhi, W C; Birk, S A

    1976-04-01

    Serum human placental lactogen levels were measured after 36 weeks' gestation in 264 serum samples from 109 women with normal pregnancies and in 137 serum samples from 70 women with pregnancies complicated by fetal intrauterine growth retardation (IGR). The fetal and placental weights were significantly lower in the IGR groups while the maternal ages were not different. There was a significantly lower hPL value at each week from 36 to 41 (except for the 39th) in the IGR group. Sixty percent of the women with IGR had hPL values less than 6 mug/ml, and 18.6% were less than 4 mug/ml. It is suggested that a low serum hPL value obtained during the last month of pregnancy should alert the physician to the possibility of intrauterine problems, including IGR.

  11. A mentally retarded patient with schizophrenia.

    Science.gov (United States)

    Rabia, K; Khoo, Em

    2008-01-01

    Schizophrenia is one of the most incapacitating forms of mental disorder that runs a chronic and relapsing course. It typically starts in adolescence or early adulthood and can be life-long. It is more common in people with learning disabilities than in the general population. Its prodromal features include depression, anxiety, suspiciousness, social isolation and bizarre behaviour. It may result in significant functional, social and economic impairments. The care of patients with schizophrenia places a considerable burden on all carers including patient's family, health and social services. Treatment includes pharmacotherapy and psychosocial interventions. In this case report we describe a thirteen-year-old patient with schizophrenia who has a background history of mental retardation.

  12. The Helmholtz theorem and retarded fields

    Science.gov (United States)

    Heras, Ricardo

    2016-11-01

    Textbooks frequently use the Helmholtz theorem to derive expressions for electrostatic and magnetostatic fields but they do not usually apply this theorem to derive expressions for time-dependent electric and magnetic fields, even when there is no formal objection to doing so because the proof of the theorem does not involve time derivatives but only spatial derivatives. Here we address the question as to whether the Helmholtz theorem is useful in deriving expressions for the fields of Maxwell’s equations. We show that when this theorem is applied to Maxwell’s equations we obtain instantaneous expressions of the electric and magnetic fields, which are formally correct but of little practical usefulness. We then discuss two generalizations of the theorem which are shown to be useful in deriving the retarded fields.

  13. The Helmholtz theorem and retarded fields

    CERN Document Server

    Heras, Ricardo

    2016-01-01

    Textbooks frequently use the Helmholtz theorem to derive expressions for the electrostatic and magnetostatic fields but they do not usually apply this theorem to derive expressions for the time-dependent electric and magnetic fields, even when there is no formal objection to doing so because the proof of the theorem does not involve time derivatives but only spatial derivatives. Here we address the question as to whether the Helmholtz theorem is useful to derive expressions for the fields of Maxwell's equations. We show that when this theorem is applied to Maxwell's equations we obtain instantaneous expressions of the electric and magnetic fields, which are formally correct but of little practical usefulness. We then discuss two generalizations of the theorem which are shown to be useful to derive the retarded fields.

  14. Trisomy 21: from chromosomes to mental retardation.

    Science.gov (United States)

    Roubertoux, Pierre L; Kerdelhué, Bernard

    2006-05-01

    The first descriptions of the trisomy 21 phenotype were by Jean-Etienne-Dominique Esquirol (1838), Edouard Séguin (1846) and later by John L. H. Down in 1862. It took more than a century to discover the extra-chromosomal origin of the syndrome commonly called "Down's syndrome" and which, we suggest, should be referred to as "Trisomy 21". In this review we are presenting the landmarks, from the pioneering description of the syndrome in 1838 to Jérôme Lejeune's discovery of the first genetic substrate for mental retardation. The sequencing of HSA21 was a new starting point that generated transcriptome studies, and we have noted that studies of gene over-expression have provided the impetus for discovering the HSA21 genes associated with trisomy 21 cognitive impairment.

  15. Environmental monitoring of brominated flame retardants

    Science.gov (United States)

    Vagula, Mary C.; Kubeldis, Nathan; Nelatury, Charles F.

    2011-06-01

    Brominated flame retardants (BFRs) are synthetic organobromide compounds which inhibit ignition and combustion processes. Because of their immense ability to retard fire and save life and property, they have been extensively used in many products such as TVs, computers, foam, plastics etc. The five major classes of BFRs are tetrabromobisphenol-A (TBBPA), hexabromocyclododecane (HBCD), pentabromodiphenyl ether, octabromodiphenyl ether, and decabromodiphenyl ether. The last three are also commonly called PBDEs. BDE-85 and BDE-209 are the two prominent congeners of PBDEs and this study reports the adverse effects of these congeners in rodents. Exposure of rat sciatic nerves to 5 μg/mL and 20 μg/mL of BDE-85 and BDE-209 respectively lead to significant, concentration dependent reduction in nerve conduction function. Glucose absorption in the rat intestinal segments exposed to 5 μg/mL of BDE-85 and BDE-209 was significantly reduced for both the compounds tested. Lastly, mice when exposed to 0.25 mg/kg body weight for four days showed a disruption in oxidant and antioxidant equilibrium. The tissues namely liver and brain have shown increase in the levels of lipid hydroperoxides indicating oxidative stress. Moreover, all the protective enzymes namely superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, and glutathione S transferase (GST) have shown tissue specific alterations indicating the induction of damaging oxidative stress and setting in of lipid peroxidation in exposed animals. The results indicate monitoring of PBDEs in the environment is essential because levels as low as 5 μg/mL and 0.25 mg/kg body weight were able to cause damage to the functions of rodents.

  16. The Educational Meaning of Mental Retardation: Toward a More Helpful Construct. Mental Retardation and the Neglected Construct of Motivation.

    Science.gov (United States)

    Switzky, Harvey N.

    This paper examines the role of motivation in the way mental retardation is defined and treated. It reviews evidence that mental retardation involves a motivational self-system and a self-regulatory influence which, interacting with cognitive and metacognitive factors, result in inefficient learning. It suggests that individuals with mental…

  17. Flame Retardant Applications in Camping Tents and Potential Exposure.

    Science.gov (United States)

    Keller, Alexander S; Raju, Nikhilesh P; Webster, Thomas F; Stapleton, Heather M

    2014-02-11

    Concern has mounted over health effects caused by exposure to flame retardant additives used in consumer products. Significant research efforts have focused particularly on exposure to polybrominated diphenyl ethers (PBDEs) used in furniture and electronic applications. However, little attention has focused on applications in textiles, particularly textiles meeting a flammability standard known as CPAI-84. In this study, we investigated flame retardant applications in camping tents that met CPAI-84 standards by analyzing 11 samples of tent fabrics for chemical flame retardant additives. Furthermore, we investigated potential exposure by collecting paired samples of tent wipes and hand wipes from 27 individuals after tent setup. Of the 11 fabric samples analyzed, 10 contained flame retardant additives, which included tris(1,3-dichloroisopropyl) phosphate (TDCPP), decabromodiphenyl ether (BDE-209), triphenyl phosphate, and tetrabromobisphenol-A. Flame retardant concentrations were discovered to be as high as 37.5 mg/g (3.8% by weight) in the tent fabric samples, and TDCPP and BDE-209 were the most frequently detected in these samples. We also observed a significant association between TDCPP levels in tent wipes and those in paired hand wipes, suggesting that human contact with the tent fabric material leads to the transfer of the flame retardant to the skin surface and human exposure. These results suggest that direct contact with flame retardant-treated textiles may be a source of exposure. Future studies will be needed to better characterize exposure, including via inhalation and dermal sorption from air.

  18. Current-use flame retardants in the water of Lake Michigan tributaries

    Science.gov (United States)

    Guo, Jiehong; Romanak, Kevin; Westenbroek, Stephen M.; Hites, Ronald A.; Venier, Marta

    2017-01-01

    In this study, we measured the concentrations of 65 flame retardants in water samples from five Lake Michigan tributaries. These flame retardants included organophosphate esters (OPEs), brominated flame retardants (BFRs), and Dechlorane-related compounds. A total of 59 samples, including both the particulate and the dissolved phases, were collected from the Grand, Kalamazoo, Saint Joseph, and Lower Fox rivers and from the Indiana Harbor and Ship Canal (IHSC) in 2015. OPEs were the most abundant among the targeted compounds with geometric mean concentrations ranging from 20 to 54 ng/L; OPE concentrations were comparable among the five tributaries. BFR concentrations were about 1 ng/L, and the most-abundant compounds were bis(2-ethylhexyl) tetrabromophthalate, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate, and decabromodiphenyl ether. The highest BFR concentrations were measured in either the IHSC or the Saint Joseph River. The dechlorane-related compounds were detected at low concentrations (increase with their octanol–water partition coefficient. The chemical loading from all the five tributaries into Lake Michigan were <10 kg/year for the BFRs and about 500 kg/year for the OPEs.

  19. Adsorption and Flame Retardant Properties of Bio-Based Phytic Acid on Wool Fabric

    Directory of Open Access Journals (Sweden)

    Xian-Wei Cheng

    2016-04-01

    Full Text Available Bio-based phytic acid (PA as a nontoxic naturally occurring compound is a promising prospect for flame-retardant (FR modifications to polymers. In this work, PA was applied to wool fabric using an exhaustion technique, and the adsorption and FR properties of PA on wool fabric were studied. The flame retardancy of the treated wool fabrics depended greatly on the adsorption quantity of PA, which was related to the pH of treatment solution, immersing temperature and initial PA concentration. The Langmuir adsorption of PA took place due to electrostatic interactions between PA and wool fiber. The limiting oxygen index, vertical burning and pyrolysis combustion flow calorimetry tests revealed that the treated wool fabrics exhibited good flame retardancy. The measurements of the phosphorus content of the burned fabric residues and thermogravimetric analyses suggested that a significant condensed-phase FR action was applicable to the PA treated fabrics. PA treatment was found to have little adverse effect on the whiteness and mechanical performance of wool. Additionally, the washing resistance of the FR fabrics should be further improved.

  20. Fatigue crack growth retardation in spot heated mild steel sheet

    Indian Academy of Sciences (India)

    B B Verma; P K Ray

    2002-08-01

    A fatigue crack can be effectively retarded by heating a spot near the crack tip under nil remote stress condition. The subcritical spot heating at a proper position modifies the crack growth behaviour in a way, more or less, similar to specimen subjected to overload spike. It is observed that the extent of crack growth retardation increases with increasing level of overload as well as with increasing spot temperature. It is also observed that modification in crack growth behaviour is a function of location of heating spot and maximum retardation is observed at + 5 position.

  1. Synthesis and application of amino resinous intumescent flame retardants

    Institute of Scientific and Technical Information of China (English)

    Ming GAO; Rongjie YANG

    2009-01-01

    A kind of amino resinous intumescent flame retardants (IFR) was firstly synthesized, and the structure of the main composition was determined to be a caged bicyclic macromolecule containing phosphorus. The 30% weight of IFR was added into the flexible polyurethane foam (FPUF) to get retardant FPUF which has 26.5% of the limiting oxygen index. The date of CONE show that the heat release, smoke and gas of the flame retardant FPUF are much decreased and the activation energy decreases by 54kJ-mor1. It shows that the IFR can catalyze decomposition and carbonization of FPUF.

  2. Stokes polarimetry using analysis of the nonlinear voltage-retardance relationship for liquid-crystal variable retarders

    Energy Technology Data Exchange (ETDEWEB)

    López-Téllez, J. M., E-mail: jmlopez@comunidad.unam.mx; Bruce, N. C. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, Apdo. Postal 70-186, México D.F., 04510 (Mexico)

    2014-03-15

    We present a method for using liquid-crystal variable retarders (LCVR’s) with continually varying voltage to measure the Stokes vector of a light beam. The LCVR's are usually employed with fixed retardance values due to the nonlinear voltage-retardance behavior that they show. The nonlinear voltage-retardance relationship is first measured and then a linear fit of the known retardance terms to the detected signal is performed. We use known waveplates (half-wave and quarter-wave) as devices to provide controlled polarization states to the Stokes polarimeter and we use the measured Stokes parameters as functions of the orientation of the axes of the waveplates as an indication of the quality of the polarimeter. Results are compared to a Fourier analysis method that does not take into account the nonlinear voltage-retardance relationship and also to a Fourier analysis method that uses experimental voltage values to give a linear retardance function with time. Also, we present results of simulations for comparison.

  3. Stokes polarimetry using analysis of the nonlinear voltage-retardance relationship for liquid-crystal variable retarders.

    Science.gov (United States)

    López-Téllez, J M; Bruce, N C

    2014-03-01

    We present a method for using liquid-crystal variable retarders (LCVR's) with continually varying voltage to measure the Stokes vector of a light beam. The LCVR's are usually employed with fixed retardance values due to the nonlinear voltage-retardance behavior that they show. The nonlinear voltage-retardance relationship is first measured and then a linear fit of the known retardance terms to the detected signal is performed. We use known waveplates (half-wave and quarter-wave) as devices to provide controlled polarization states to the Stokes polarimeter and we use the measured Stokes parameters as functions of the orientation of the axes of the waveplates as an indication of the quality of the polarimeter. Results are compared to a Fourier analysis method that does not take into account the nonlinear voltage-retardance relationship and also to a Fourier analysis method that uses experimental voltage values to give a linear retardance function with time. Also, we present results of simulations for comparison.

  4. Synergistic Effect of Nanosilica Aerogel with Phosphorus Flame Retardants on Improving Flame Retardancy and Leaching Resistance of Wood

    Directory of Open Access Journals (Sweden)

    Xiaodan Zhu

    2014-01-01

    Full Text Available Nanosilica (Nano-SiO2 sol fabricated by a sol-gel process was introduced into wood modification with phosphorus flame retardants to improve the flame retardancy and leaching resistance of wood. The obtained materials were characterized by scanning electron microscopy and energy dispersive spectrometer (SEM-EDS, thermogravimetric analysis (TGA, cone calorimetric (CONE, and infrared spectroscopy (FT-IR. The residual rate of flame retardants before and after leaching was determinated by a leaching resistance. The results showed that the phosphorus flame retardants and SiO2 sol could reside in the poplar wood and are widely distributed in the vessels, pits, wood timber, and the spaces between wood cells of poplar substrate. TGA and CONE results indicated that the introduction of nano-SiO2 aerogel with phosphorus flame retardants had a significantly synergistic effect on improving the flame retardancy and inhibiting the release of smoke and toxic gases. In addition, the leaching resistance test, combined with infrared analysis and EDS analysis, confirmed that the phosphorus flame retardants were able to be fixed by SiO2 aerogel in the wood.

  5. SELF-CONTROL FORMATION TECHNOLOGY FOR PRIMARY SCHOOL CHILDREN WITH MILD MENTAL RETARDATION IN LEARNING PROCESS

    Directory of Open Access Journals (Sweden)

    Vera A. Galkina

    2015-01-01

    Full Text Available The purpose of the article is to present self-control development technology meeting up-to-date requirements in the special education for pupils with mild mental retardation; to reveal the self-control special features for children of the studied category found during the experiment; to show necessity of the task-oriented work. Methods. The methods involve theoretical analysis of relevant psychologicpedagogical and methodical literature; empiric methods (conversation, writing tasks, observation; pedagogic experiment; quantitative and qualitative analysis. Results. The article contains the data obtained during the experiment concerning study of the self-control special features for primary school children with mild mental retardation in learning process. The author describes and scientifically justifies the self-control development technology based on the step-bystep approach for children of the studied category. The revealed reasons of low self-control level for primary school children with intellectual disorder are proven by qualitative and quantitative analysis. The presented experimental results confirm the developed technology efficiency and can be applied while studying of all disciplines at primary school. Scientific novelty. For the first time the unified (may be used at all subjects and comprehensive (for all self-control components self-control development technology was developed and proven for primary school children with mild mental disorder in learning process; transient phase necessity is proved and justified for mastering all control kinds by primary school children with mild mental retardation. Practical significance. The developed technology allows qualitative enhancement of learning activities for primary school children with mild mental retardation. The research results may be used in both correctional and educational work at special (correctional schools (type VIII and at general-education schools. In addition the results

  6. Mesic retardation and the triton binding energy

    Energy Technology Data Exchange (ETDEWEB)

    Brandenburg, R.A.; Chulick, G.S.; Machleidt, R.; Picklesimer, A.; Thaler, R.M.

    1988-09-01

    The relationship between the apparently successful result for the triton binding energy obtained from the static Bonn potentials and the underlying meson theory is investigated. The triton binding is shown to be strongly dependent upon mesic retardation and associated explicit energy dependences in the meson theory of the nucleon-nucleon interaction. Because it is a much closer representation of the full interaction than are its energy-independent counterparts, the energy-dependent one-boson-exchange potential representation of the Bonn interaction is used to gauge the implications of the full interaction. This one-boson-exchange potential, with or without corrections to adapt it for use in conjunction with nonrelativistic (Schroedinger) three-body equations, predicts a triton binding of only approx.6.7 MeV, as compared to a result of about 8.4 MeV obtained with the energy-independent potentials. This difference is traced to the combination of the explicit energy-dependence and the implicit energy dependence introduced through the tensor force, especially in the /sup 3/S/sub 1/ partial wave. This provides a new perspective on the success of the static Bonn potentials relative to other realistic potentials and relative to the meson-theoretic framework. Implications, especially with regard to the need for investigations of consistent three-body forces, are discussed.

  7. Mesic retardation and the triton binding energy

    Science.gov (United States)

    Brandenburg, R. A.; Chulick, G. S.; Machleidt, R.; Picklesimer, A.; Thaler, R. M.

    1988-09-01

    The relationship between the apparently successful result for the triton binding energy obtained from the static Bonn potentials and the underlying meson theory is investigated. The triton binding is shown to be strongly dependent upon mesic retardation and associated explicit energy dependences in the meson theory of the nucleon-nucleon interaction. Because it is a much closer representation of the full interaction than are its energy-independent counterparts, the energy-dependent one-boson-exchange potential representation of the Bonn interaction is used to gauge the implications of the full interaction. This one-boson-exchange potential, with or without corrections to adapt it for use in conjunction with nonrelativistic (Schrödinger) three-body equations, predicts a triton binding of only ~6.7 MeV, as compared to a result of about 8.4 MeV obtained with the energy-independent potentials. This difference is traced to the combination of the explicit energy-dependence and the implicit energy dependence introduced through the tensor force, especially in the 3S1 partial wave. This provides a new perspective on the success of the static Bonn potentials relative to other realistic potentials and relative to the meson-theoretic framework. Implications, especially with regard to the need for investigations of consistent three-body forces, are discussed.

  8. Inhibition of Complement Retards Ankylosing Spondylitis Progression

    Science.gov (United States)

    Yang, Chaoqun; Ding, Peipei; Wang, Qingkai; Zhang, Long; Zhang, Xin; Zhao, Jianquan; Xu, Enjie; Wang, Na; Chen, Jianfeng; Yang, Guang; Hu, Weiguo; Zhou, Xuhui

    2016-01-01

    Ankylosing spondylitis (AS) is a chronic axial spondyloarthritis (SpA) resulting in back pain and progressive spinal ankyloses. Currently, there are no effective therapeutics targeting AS largely due to elusive pathogenesis mechanisms, even as potential candidates such as HLA-B27 autoantigen have been identified. Herein, we employed a proteoglycan (PG)-induced AS mouse model together with clinical specimens, and found that the complement system was substantially activated in the spinal bone marrow, accompanied by a remarkable proportion alteration of neutrophils and macrophage in bone marrow and spleen, and by the significant increase of TGF-β1 in serum. The combined treatment with a bacteria-derived complement inhibitor Efb-C (C-terminal of extracellular fibrinogen-binding protein of Staphylococcus aureus) remarkably retarded the progression of mouse AS by reducing osteoblast differentiation. Furthermore, we demonstrated that two important modulators involved in AS disease, TGF-β1 and RANKL, were elevated upon in vitro complement attack in osteoblast and/or osteoclast cells. These findings further unravel that complement activation is closely related with the pathogenesis of AS, and suggest that complement inhibition may hold great potential for AS therapy. PMID:27698377

  9. Some plant extracts retarde nitrification in soil

    Directory of Open Access Journals (Sweden)

    Abdul–Mehdi S. AL-ANSARI

    2015-12-01

    Full Text Available An incubation experiment was conducted to evaluate the effect of aqueous extracts of 17 plant materials on nitrification inhibition of urea- N in soil as compared with chemical inhibitor Dicyandiamide (DCD. Plant materials used in study were collected from different areas of Basrah province, south of Iraq. Aqueous extracts were prepared at ratio of 1:10 (plant material: water and added at conc. of 0.05, 0.10 and 0.20 ml g– 1 soil to loamy sand soil. DCD was added to soil at rate of 50 µg g-1 soil . Soil received urea at rate of 1000 µg N g-1 soil. Treated soils were incubated at 30 OC for 40 days. Results showed that application of all plant extracts, except those of casuarina, date palm and eucalyptus to soil retarded nitrification in soil. Caper, Sowthistle ,bladygrass and pomegranate extracts showed highest inhibition percentage (51, 42, 40 and 40 %, respectively and were found to be more effective than DCD (33 %. Highest inhibition was achieved by using those extracts at conc. of 0.1 ml g-1 soil after 10 days of incubation . Data also revealed that treated soil with these plant extracts significantly increased amount of NH4+–N and decreased amount of NO3-–N accumulation in soil compared with DCD and control treatments. Results of the study suggested a possibility of using aqueous extracts of some studied plants as potent nitrification inhibitor in soil.

  10. Alpha thalassaemia-mental retardation, X linked

    Directory of Open Access Journals (Sweden)

    Gibbons Richard

    2006-05-01

    Full Text Available Abstract X-linked alpha thalassaemia mental retardation (ATR-X syndrome in males is associated with profound developmental delay, facial dysmorphism, genital abnormalities and alpha thalassaemia. Female carriers are usually physically and intellectually normal. So far, 168 patients have been reported. Language is usually very limited. Seizures occur in about one third of the cases. While many patients are affectionate with their caregivers, some exhibit autistic-like behaviour. Patients present with facial hypotonia and a characteristic mouth. Genital abnormalities are observed in 80% of children and range from undescended testes to ambiguous genitalia. Alpha-thalassaemia is not always present. This syndrome is X-linked recessive and results from mutations in the ATRX gene. This gene encodes the widely expressed ATRX protein. ATRX mutations cause diverse changes in the pattern of DNA methylation at heterochromatic loci but it is not yet known whether this is responsible for the clinical phenotype. The diagnosis can be established by detection of alpha thalassaemia, identification of ATRX gene mutations, ATRX protein studies and X-inactivation studies. Genetic counselling can be offered to families. Management is multidisciplinary: young children must be carefully monitored for gastro-oesophageal reflux as it may cause death. A number of individuals with ATR-X are fit and well in their 30s and 40s.

  11. Teaching about Older People with Mental Retardation: An Educational Model.

    Science.gov (United States)

    Kropf, Nancy P.; And Others

    1993-01-01

    The University of Georgia model curriculum to prepare students to work with mentally retarded older adults has six units: population overview, physiological issues, mental health issues, social support systems, service delivery networks, and legal/ethical issues. (SK)

  12. The Effects of Institutionalisation on Retardates Social Independence.

    Science.gov (United States)

    Burkhart, G.; Seim, R.

    1979-01-01

    Forty retarded adults were the Ss of a study to evaluate the hypothesis that individuals who have been institutionalized for a greater percentage of their lifetime are more socially immature than those institutionalized for a smaller percentage. (CL)

  13. Management problems of mentally retarded children and their families.

    Science.gov (United States)

    Gayton, W F

    1975-08-01

    Pediatricians faced with the difficult task of providing management services to mentally retarded children and their families are confronted with a number of difficult problems. These range all the way from deciding how to inform parents that their child is retarded to dealing with grandparents who are a source of stress. Successful handling of these problems requires a recognition that management is central to the care of the mentally retarded child. The needs of mentally retarded children and their families will not be met by interacting with families only around issues of acute physical illness. Attention must be directed toward psychosocial as well as medical variables and the emphasis must be on the total family system.

  14. Reality Therapy with Institutionalized Emotionally Disturbed Mentally Retarded Adolescents.

    Science.gov (United States)

    Dolly, John P.; Page, D. Patricia

    1981-01-01

    The study evaluated a reality therapy program used with 20 institutionalized mentally retarded (mild to profound) and emotionally disturbed adolescents residing in an institution. Results indicated that 17 of the Ss increased adaptive behaviors and all decreased maladaptive behaviors. (DB)

  15. Psychosocial Impacts of Mentally Retarded Children on Parents in ...

    African Journals Online (AJOL)

    Psychosocial Impacts of Mentally Retarded Children on Parents in Sudan. ... effects are directly related to the age, number of handicapped children in the family as well as the degree ... Keywords: Anxiety, depression, divorce, marital stability.

  16. Stress retardation versus stress relaxation in linear viscoelasticity

    CERN Document Server

    Christov, Ivan C

    2016-01-01

    We present a preliminary examination of a new approach to a long-standing problem in non-Newtonian fluid mechanics. First, we summarize how a general implicit functional relation between stress and rate of strain of a continuum with memory is reduced to the well-known linear differential constitutive relations that account for "relaxation" and "retardation." Then, we show that relaxation and retardation are asymptotically equivalent for small Deborah numbers, whence causal pure relaxation models necessarily correspond to ill-posed pure retardation models. We suggest that this dichotomy could be a possible way to reconcile the discrepancy between the theory of and certain experiments on viscoelastic liquids that are conjectured to exhibit only stress retardation.

  17. The involvement of epigenetic defects in mental retardation.

    Science.gov (United States)

    Franklin, Tamara B; Mansuy, Isabelle M

    2011-07-01

    Mental retardation is a group of cognitive disorders with a significant worldwide prevalence rate. This high rate, together with the considerable familial and societal burden resulting from these disorders, makes it an important focus for prevention and intervention. While the diseases associated with mental retardation are diverse, a significant number are linked with disruptions in epigenetic mechanisms, mainly due to loss-of-function mutations in genes that are key components of the epigenetic machinery. Additionally, several disorders classed as imprinting syndromes are associated with mental retardation. This review will discuss the epigenetic abnormalities associated with mental retardation, and will highlight their importance for diagnosis, treatment, and prevention of these disorders. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Inferential reading abilities of mildly mentally retarded and nonretarded students.

    Science.gov (United States)

    Bos, C S; Tierney, R J

    1984-07-01

    The inferential operations of mildly mentally retarded students reading at the intermediate level were investigated using methods based on discourse comprehension theory. We hypothesized that problems encountered in reading by these students are related to difficulties in generating logical inferences. Mildly retarded junior-high students and nonretarded third-grade students of the same reading comprehension level read and recalled a descriptive expository and a narrative passage. On the expository passage mildly retarded students generated the same quantity of inferences as did nonretarded students, but the inferences were qualitatively inferior. On the narrative passage the differences between the two groups were not significant. These findings were discussed in relation to the cognitive functioning of mildly retarded students.

  19. Aerobic Dance and the Mentally Retarded--A Winning Combination.

    Science.gov (United States)

    Barton, Bonnie J.

    1982-01-01

    The results of a study on an experimental dance program for mentally retarded children show that these children can improve in physical fitness and that success through physical activities can enhance their generally poor self-concept. (JN)

  20. Bounds for solutions to retarded nonlinear double integral inequalities

    Directory of Open Access Journals (Sweden)

    Sabir Hussain

    2014-12-01

    Full Text Available We present bounds for the solution to three types retarded nonlinear integral inequalities in two variables. By doing this, we generalizing the results presented in [3,12]. To illustrate our results, we present some applications.

  1. Aryl Polyphosphonates: Useful Halogen-Free Flame Retardants for Polymers

    Directory of Open Access Journals (Sweden)

    Li Chen

    2010-10-01

    Full Text Available Aryl polyphosphonates (ArPPN have been demonstrated to function in wide applications as flame retardants for different polymer materials, including thermosets, polycarbonate, polyesters and polyamides, particularly due to their satisfactory thermal stability compared to aliphatic flame retardants, and to their desirable flow behavior observed during the processing of polymeric materials. This paper provides a brief overview of the main developments in ArPPN and their derivatives for flame-retarding polymeric materials, primarily based on the authors’ research work and the literature published over the last two decades. The synthetic chemistry of these compounds is discussed along with their thermal stabilities and flame-retardant properties. The possible mechanisms of ArPPN and their derivatives containing hetero elements, which exhibit a synergistic effect with phosphorus, are also discussed.

  2. Retarded Boson-Fermion interaction in atomic systems

    Indian Academy of Sciences (India)

    Sambhu N Datta

    2007-09-01

    The retarded interaction between an electron and a spin-0 nucleus, that has been derived from electro-dynamical perturbation theory is discussed here. A brief account of the derivation is given. The retarded form is correct through order 2/2. Use of the relative coordinates leads to an effective oneelectron operator that can be used through all orders of perturbation theory. A few unitary transformations give rise to the interaction that is valid in the non-relativistic limit.

  3. Porous Flame-retarded Asphalt Pavement for Highway Tunnel

    Institute of Scientific and Technical Information of China (English)

    HU Shuguang; HUANG Shaolong; Ding Qingjun

    2008-01-01

    A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt (PA) and flame-retarded porous asphalt (FRPA) were studied comparing with cement concrete pavement, dense-graded HMA and S MA. Results of burning test and pavement performance test indicate that FRPA is appropriate and suitable as the pavement material of highway tunnel.

  4. Flame Retardant Applications in Camping Tents and Potential Exposure

    OpenAIRE

    Keller, Alexander S.; Raju, Nikhilesh P.; Webster, Thomas F.; Stapleton, Heather M.

    2014-01-01

    Concern has mounted over health effects caused by exposure to flame retardant additives used in consumer products. Significant research efforts have focused particularly on exposure to polybrominated diphenyl ethers (PBDEs) used in furniture and electronic applications. However, little attention has focused on applications in textiles, particularly textiles meeting a flammability standard known as CPAI-84. In this study, we investigated flame retardant applications in camping tents that met C...

  5. STRESS & COPING STRATEGIES IN FAMILIES OF MENTALLY RETARDED CHILDREN

    Directory of Open Access Journals (Sweden)

    Mukesh

    2015-06-01

    Full Text Available BACKGROUND : Families with mentally retarded children experience a great physical and psychosocial stress which demands various psychosocial strategies for effective coping. METHODOLOGY : This study was conducted in the department of Psychiatry , Government Medical College , Kota (Raj. in 2006 - 07 with the objectives of finding out the stress & coping strategies and the factors influencing these strategies in the families with mentally retarded children. Fifty mentally reta rded children were divided into two groups - Group A comprising children with IQ more or equal to 50 (n=28 and Group B comprising children having IQ less than 50 (n=22 . Parents of selected mentally retarded children were interviewed by using semi structur ed Performa containing – personnel identification data , Family Interview for Stress and Coping in Mental Retardation (FISC - MR , NIMH – Family Efficacy Scale (NIMH - FES , Problem Behavior Check List. Obtained data was analyzed by using unpaired t test , Pearson`s correlation coefficient & z - score. RESULTS : In various dimensions of perceived stress , families with mentally retarded children with IQ ˂50 (Group B experienced significantly higher daily care stress , emotional stress , social stress and total pe rceived stress than the families with mentally retarded children with IQ≥50 (Group A . Families in both groups used similar coping strategies (i.e. , awareness about mental retardation , attitude and expectation , rearing practices and social support except global support strategy which was used significantly higher by the families of children with IQ<5o. Having a female mentally retarded child and nuclear family were the factors associated with higher stress in families.

  6. Pyrolytic characteristics of burning residue of fire-retardant wood

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guangjie; LUO Wensheng; Furuno T; REN Qiang; MA Erni

    2007-01-01

    In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood,a multifunctional fire-resistance test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood.Samples at different distances from the combustion surface were obtained and a thennogravimetric analysis (TG) was applied to test the pyrolytic process of the burning residue in an atmosphere of nitrogen.The results showed that:1) there was little difference between fireretardant wood and its residue in the initial temperature of thermal degradation.The initial temperature of thermal degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample;2) the temperature of the flame retardant in fire-retardant wood was 200℃ in the differential thermogravimetry (DTG).The peak belonging to the flame retardant tended to dissipate during the time of burning;3) for the burning residue of fire-retardant wood,the peak belonging to hemicellulose near 230℃ in the DTG disappeared and there was a gentle shoulder from 210 to 240℃;4) the temperature of the main peaks of the fireretardant wood and its burning residue in DTG was 100℃ lower than that of the untreated wood and its burning residue.The rate of weight loss also decreased sharply;5) the residual weight of fire-retardant wood at 600~C clearly increased compared with that of untreated wood.Residual weight of the burning residue increased markedly as the heating temperature increased when burning;6) there was a considerable difference with respect to the thermal degradation temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood.

  7. A Case with Mental Retardation, Gynecomastia and Dysmorphic Features

    Directory of Open Access Journals (Sweden)

    Ozge Ozalp Yuregir

    2012-02-01

    Full Text Available The 17 years old boy was diagnosed as Borjeson Forsmann Lehmann Syndrome who was referred to our Genetic Diagnosis Center for his dysmorphic features, obesity, gynecomasty and mental retardation . There are so many diseases in differantial diagnosis of obesity and mental retardation that BFLS is a rare one of them. We aimed to discuss the findings of the patient clinically diagnosed as BFLS within the scope of literature. [Cukurova Med J 2012; 37(1.000: 60-63

  8. Flame retardancy of paulownia wood and its mechanism

    OpenAIRE

    2007-01-01

    Paulownia wood (Pauloumia tomentosa) is a special kind of wood material in that it has especially excellent flame retardancy. Using this property, it has been commonly used to make clothing wardrobes for a long time in Japan. In this research, the flame retardancy of paulownia wood has been verified by heating experiments and cone calorimeter testing. The structure and tissue of the material have been analyzed by scanning electron microscope and other methods. Moreover, the mechanism of the f...

  9. Mao Yuyan Brings New Fortune to Mentally Retarded Children

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    BEIJING Fortune Training School for Mentally Retarded Children aims at developing the abilities and independence of mentally disabled children. Located at Fourth Ring Road in Chaoyang District, northeast Beijing, the school provides good housing and firstrate teaching facilities for 60 mentally retarded children aged 3 to 10. With a staff of 18, the school finally settled here in 1996 with the assistance of the Beijing municipal government and Chaoyang District government, and funds contributed by organizations in Hong

  10. Migration and Retardation of Chemical Toxic Components from Radioactive Waste - Hydrochemical Aspects

    Energy Technology Data Exchange (ETDEWEB)

    Jedinakova-Krizova, V.; Hanslik, E.

    2003-02-24

    A systematic analysis of nuclear power plant (NPP) operation and radioactive wastes disposal (near-surface disposal and geologic disposal) in underground repositories has provided the basis for a comparison between the radiotoxicity and chemotoxicity as part of an EIA (environmental impact assessment) procedure. This contribution summarizes the hydrochemical mechanisms of transport and retardation processes, chemistry and migration behavior of radionuclides and chemical toxics in natural sorbents, especially bentonites. The effect of solubility and dissolution reactions, diffusion and sorption/desorption, complexation and variations in the aqueous phase composition, pH-value and oxidation-reduction properties and other phenomena affecting distribution coefficients (Kd values) is discussed.

  11. Development of flame retardant PV module encapsulants: Volume 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Galica, J.P.

    1998-06-01

    This Phase 1 final report covers the work performed by Springborn Testing and Research, Inc., for the period October 1, 1997 to June 30, 1998 under the Department of Energy Cooperative Agreement Number DE-FC36-97GO10255, entitled Development of Flame Retardant PV Module Encapsulants. While use of roof-mounted arrays has always been an attractive means of deploying PV, only within recent years have such building integrated concepts (BIPV) found renewed interest among module makers and end-users. Prior to building integrated and rooftop applications, flammability requirements for modules have not been a great industry concern. However, with growing interest in BIPV and the requirement for building code requirements for commercial and industrial structures, flammability issues have become a barrier to entry for many module constructions into this potentially huge domestic market for PV. The overall goal of the 3 phase PV BONUS two project is to develop and commercialize a line of fire retardant encapsulation materials to serve the emerging building integrated and building mounted PV market. The objectives of the Phase 1 effort are limited to concept development and business planning activities.

  12. Flame Retardant Exposure among Collegiate U.S. Gymnasts

    Science.gov (United States)

    Carignan, Courtney C.; Heiger-Bernays, Wendy; McClean, Michael D.; Roberts, Simon C.; Stapleton, Heather M.; Sjödin, Andreas; Webster, Thomas F.

    2013-01-01

    Gymnastics training facilities contain large volumes of polyurethane foam, a material that often contains additive flame retardants such as PentaBDE. While investigations of human exposure to flame retardants have focused on the general population, potentially higher than background exposures may occur in gymnasts and certain occupational groups. Our objectives were to compare PentaBDE body burden among gymnasts to the general U.S. population and characterize flame retardants levels in gym equipment, air and dust. We recruited 11 collegiate female gymnasts (ages 18–22) from one gym in the Eastern U.S. The geometric mean (GM) concentration of BDE-153 in gymnast sera (32.5 ng/g lipid) was 4–6.5 times higher than general U.S. population groups. Median concentrations of PentaBDE, TBB and TBPH in paired handwipe samples were 2–3 times higher after practice compared to before, indicating the gymnasts contacted these flame retardants during practice. GM concentrations of PentaBDE, TBB and TBPH were 1-3 orders of magnitude higher in gym air and dust than in residences. Our findings suggest that these collegiate gymnasts experienced higher exposures to PentaBDE flame retardants compared to the general U.S. population and that gymnasts may also have increased exposure to other additive flame retardants used in polyurethane foam such as TBB and TBPH. PMID:24195753

  13. The frequency of Toxocara infection in mental retarded children

    Directory of Open Access Journals (Sweden)

    Mustafa Kaplan

    2004-03-01

    Full Text Available Human toxocariasis is commonly seen in places where stray and Toxocara canis-infected dog population is high. There is a strong correlation between frequency of Toxocara infection, life style, and infection risk. Institutionalization of mental retarded patients increases to risk of toxocariasis. In this study, we aimed at investigating the frequency of Toxocara infection among children with mental retardation not requiring institutionalization. The study included 96 cases, who had educatable mental retardation and 85 healthy subjects who comprised the control group. Anti-Toxocara IgG or IgM antibodies were investigated in all serum samples, using ELISA method. The frequency of Toxocara infection was found significantly higher in mental retarded cases than in those in the control group (18.8% and 7.1% respectively (p 0.05. We did not find any significant difference between Toxocara seropositive and seronegative mental retarded children in terms of demographic factors and epidemiological factors that could increase the risk of Toxocara infection (p > 0.05. The present study is the first seroprevalence study carried out with a mental retarded group not requiring institutionalization. Determination of high frequency of Toxocara infection suggests that these subjects constitute a risk factor for Toxocara infection, which may be attributed to their behavioural patterns.

  14. Flame retardant exposure among collegiate United States gymnasts.

    Science.gov (United States)

    Carignan, Courtney C; Heiger-Bernays, Wendy; McClean, Michael D; Roberts, Simon C; Stapleton, Heather M; Sjödin, Andreas; Webster, Thomas F

    2013-12-03

    Gymnastics training facilities contain large volumes of polyurethane foam, a material that often contains additive flame retardants such as PentaBDE. While investigations of human exposure to flame retardants have focused on the general population, potentially higher than background exposures may occur in gymnasts and certain occupational groups. Our objectives were to compare PentaBDE body burden among gymnasts to the general United States population and characterize flame retardants levels in gym equipment, air, and dust. We recruited 11 collegiate female gymnasts (ages 18-22) from one gym in the eastern United States. The geometric mean (GM) concentration of BDE-153 in gymnast sera (32.5 ng/g lipid) was 4-6.5 times higher than in the general United States population groups. Median concentrations of PentaBDE, TBB, and TBPH in paired handwipe samples were 2-3 times higher after practice compared to before, indicating the gymnasts contacted these flame retardants during practice. GM concentrations of PentaBDE, TBB, and TBPH were 1-3 orders of magnitude higher in gym air and dust than in residences. Our findings suggest that these collegiate gymnasts experienced higher exposures to PentaBDE flame retardants compared to the general United States population and that gymnasts may also have increased exposure to other additive flame retardants used in polyurethane foam such as TBB and TBPH.

  15. Autism and Mental Retardation of Young Children in China

    Institute of Scientific and Technical Information of China (English)

    XIN ZHANG; CHENG-YE JI

    2005-01-01

    Objective To understand the prevalence and rehabilitation status of autism and mental retardation in China. Methods Screening test and clinical assessment were conducted for the diagnosis of autism and mental retardation. The assessment included investigation of the histories of medical conditions and development of these two disorders, utilization and needs for the rehabilitation service, and related intellectual and behavioral appraisal. Results Among the 7345 children investigated, the prevalence of autism disorder was 1.10 cases per 1000 children aged 2-6 years (95% CI=0.34 to 2.54), and the prevalence of mental retardation was 10.76 cases per 1000 children (95% CI=8.40 to 13.12). All the children suffering from autistic disorder were intellectually disabled, whereas 31.0% of the non-autism mental retardates had other disabilities. The medical conditions prior to birth and perinatal period were important potential factors for autism. Half of the autistic children and 84% of the children with non-autism mental retardation had never received any rehabilitative service. Conclusions The prevalence of autistic disorder in children aged 2-6 years in Tianjin is rather high. It is urgent to improve the status of the autistic and intelligently disabled young children in China. In order to upgrade the level of early diagnostic and improve the intervention to autism and mental retardation, public awareness and training courses should be heightened.

  16. Tapentadol retard en el dolor crónico intenso Tapentadol retard for severe chronic pain

    Directory of Open Access Journals (Sweden)

    L. M. Torres Morera

    2011-10-01

    Full Text Available Desde la introducción en España de la primera morfina de administración oral, en el año 1988, se ha ido evolucionando en la biodisponibilidad de fármacos opioides potentes no administrados por vía endovenosa. Las formulaciones que permiten la absorción de estos fármacos por la piel o por la mucosa oral han supuesto un antes y un después en la administración de medicación analgésica. Posteriormente, las nuevas formas de liberación inmediata o liberación controlada han acabado de perfilar la seguridad y eficacia de estos nuevos fármacos opioides. Tapentadol retard es un fármaco analgésico de acción central de última generación, aprobado tanto por la EMA ("European Medicines Agency" en 2010 como recientemente por la Agencia Española de Medicamentos y Productos Sanitarios ("AEMPS" para el tratamiento del dolor crónico intenso. La sinergia de sus dos mecanismos de acción, el agonismo μ-opioide y la inhibición de la recaptación de noradrenalina permite abordar el dolor desde diferentes mecanismos fisiológicos. Tapentadol retard se absorbe rápidamente tras su administración oral y es excretado casi exclusivamente vía renal. Así como la eficacia analgésica de otros opioides, como codeína y tramadol dependen de su actividad metabólica, la analgesia producida por tapentadol se debe a la acción de la molécula principal, sin metabolitos farmacológicamente activos. Los trabajos analizados en esta revisión demuestran la eficacia de tapentadol retard en el tratamiento del dolor de moderado a intenso en pacientes con dolor lumbar crónico, dolor crónico por artrosis de rodilla o cadera y también en pacientes con dolor por neuropatía diabética. En aspectos de seguridad, este fármaco presenta un perfil de tolerabilidad superior al de los analgésicos opioides actuales, lo cual le confiere un potencial importante en el tratamiento de dolor por procesos crónicos. En esta revisión bibliográfica se hace análisis del

  17. Fire-retardant mechanism of fire-retardant FRW by FTIR

    Institute of Scientific and Technical Information of China (English)

    WANG Qingwen; LI Jian; LI Shujun

    2006-01-01

    The structures of the solid state products formed by the partial combustion of Korean pine wood treated with fire-retardant FRW were analyzed by microscopic FTIR.The volatile pyrolytic products of basswood (Tilia amurensis)specimens treated with FRW and its components guanylurea phosphate and boric acid were analyzed by GC-FTIR.The pyrolytic and charring process,the effects of fire-retardant,and the structural characteristics of the pyrolytic products were discussed.It was concluded that upon heating and by the catalysis of FRW and its decomposition products reactions of wood took place successively,namely the dehydration of polysaccharide,the elimination of acetic acid from hemicellulose,the degradation of polysaccharide,the degradation of lignin,the polymerization of the pyrolytic products of wood,reactions of oxygen-element-elimination of aliphatic polymers and the structural change of the latter to form aromatic structures,and charring.The pyrolysis process of wood was altered and the yield of volatile pyrolytic products was decreased by FRW treatment.

  18. Unexplained mental retardation: is brain MRI useful?

    Energy Technology Data Exchange (ETDEWEB)

    Decobert, Fabrice; Merzoug, Valerie; Kalifa, Gabriel; Adamsbaum, Catherine [Saint Vincent de Paul Hospital, Department of Radiology, 75674 Paris Cedex 14 (France); Grabar, Sophie [Cochin Hospital, Department of Biostatistics and Medical Information, Paris (France); Ponsot, Gerard [Saint Vincent de Paul Hospital, Department of Neuropaediatrics, Paris (France); Des Portes, Vincent [Saint Vincent de Paul Hospital, Department of Neuropaediatrics, Paris (France); Debrousse Hospital, Department of Neuropaediatrics, Lyon (France)

    2005-06-01

    Mental retardation (MR), defined as an IQ below 70, is a frequent cause of consultation in paediatrics. To evaluate the yield of brain MRI in the diagnostic work-up of unexplained MR in children. Patients and methods: The MRI features and clinical data of 100 patients (age 1-18 years) affected with non-progressive MR of unknown origin were compared to an age-matched control group (n=100). Two radiologists conducted an independent review of the MRI scans. Univariate and multivariate analyses showed a higher incidence of brain anomalies in the MR group than in the control group (53 vs 17, OR=5.7 [2.9-11.1]), for signal abnormalities within the periventricular white matter (OR=20.3 [2.6-155.3]), lateral ventricular dilatation (OR=15.6 [2.0-124]), mild corpus callosum abnormalities (shortness, atrophy) (OR=6.8 [1.8-25.6]) and subtle cerebellar abnormalities, including fissure enlargement (OR=5.2 [1.1-26.2]). The diagnostic value of MRI abnormalities was considered good in 5% of patients (Alexander disease n=1, diffuse cortical malformation n=1, leukomalacia n=1, vermian agenesis n=1, commissural agenesis n=1), and weak in 48% of patients, in whom non-specific abnormalities did not lead to a diagnosis. Some clinical features resulted in a significantly higher percentage of abnormal MRI scans: abnormal neurological examination (82% vs 47%, P=0.008), abnormal skull circumference (66% vs 49%, P=0.04). Motor delay was associated with cerebellar abnormalities (P=0.01). (orig.)

  19. Determinants of growth retardation in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Aerts Denise

    2004-01-01

    Full Text Available A cross-sectional population-based study of determinants of growth retardation in under-five children (3,389 in the city of Porto Alegre, Rio Grande do Sul, Brazil estimated odds ratios (OR for stunting, defined as height-for-age < -2 z-scores of the NCHS standards. Hierarchical modeling based on a framework of the process of stunting was used. Stunting prevalence was 6.8%; the main determinants were per capita family income < 0.8 times the minimum wage (OR: 3.95; 95%CI: 2.10-7.42, maternal illiteracy (OR: 17.17; 95%CI: 4.43-66.54, living in a wooden or mixed-construction house (OR: 2.33; 95%CI: 1.35-4.01, inadequate housing (OR: 2.75; 95%CI: 1.70-4.43, maternal age at the child's birth < 20 years (OR: 1.73; 95%CI: 1.11-2.70, being an adopted child (OR: 3.28; 95%CI: 1.52-7.07, third-born child or greater (OR: 2.04; 95%CI: 1.15-3.62, birth interval < 24 months since previous child (OR: 1.69; 95%CI: 1.13-2.53, subsequent sibling (OR: 1.91; 95%CI: 1.16-3.13, multiple birth (OR: 2.40; 95%CI: 1.04-5.50, low birth weight (OR: 3.79; 95%CI: 2.38-6.02, and hospitalization in the first year of life (OR: 1,65; 95%CI: 1.01-2.68.The findings can be used by primary healthcare services to design specific interventions to prevent stunting.

  20. Reproductive rights of mentally retarded persons.

    Science.gov (United States)

    Katalinić, Sanja; Sendula-Jengić, Vesna; Sendula-Pavelić, Martina; Zudenigo, Slaven

    2012-03-01

    Mental retardation denotes sub-average intellectual functioning, based on IQ, i.e. the inability of normal learning, accompanied by behavioral and developmental disorders. Persons with impairments (cognitive, motor, sensory or psychiatric) have often been, both through human history and today victims of discrimination and deprived of their basic human rights, both in the public and the private life spheres. Since the end of the 20th century, throughout the developed world, many disabled persons can accomplish their dreams and rights. However, the issue of sexuality is still an obstacle in realizing oneself as a whole person, of course in accordance with personal psychophysical abilities. The greatest problem is present in persons with severe disablement, considered not apt enough for information on sexuality and for expressing themselves as persons with their own sexual needs. Thus it is desirable to observe each disabled person individually and flexibly enough in order to establish parameters for the functioning of an intimate affair on the level of understanding and assent. The legal system must protect the most vulnerable and ensure for them the right of choice and consent, as well as the possibility of fulfilling their sexual needs, so that they could love and be loved. Naturally, the system must be built on foundations that satisfy the needs of its users, but also of persons engaged in work with them. Sex education should contain information regarding biological, socio-cultural and spiritual dimensions of sexuality, including cognitive, affective and behavioral domains. Unfortunately, very few educational programs with such aims provide sex education, not only for the disabled young population but also for the healthy. This review article is based on international investigations and Croatian legislative postulates. Its aim is to focus the attention of both professionals and non-professionals on this delicate problem.

  1. X-linked mental retardation and epigenetics.

    Science.gov (United States)

    Froyen, Guy; Bauters, Marijke; Voet, Thierry; Marynen, Peter

    2006-01-01

    The search for the genetic defects in constitutional diseases has so far been restricted to direct methods for the identification of genetic mutations in the patients' genome. Traditional methods such as karyotyping, FISH, mutation screening, positional cloning and CGH, have been complemented with newer methods including array-CGH and PCR-based approaches (MLPA, qPCR). These methods have revealed a high number of genetic or genomic aberrations that result in an altered expression or reduced functional activity of key proteins. For a significant percentage of patients with congenital disease however, the underlying cause has not been resolved strongly suggesting that yet other mechanisms could play important roles in their etiology. Alterations of the 'native' epigenetic imprint might constitute such a novel mechanism. Epigenetics, heritable changes that do not rely on the nucleotide sequence, has already been shown to play a determining role in embryonic development, X-inactivation, and cell differentiation in mammals. Recent progress in the development of techniques to study these processes on full genome scale has stimulated researchers to investigate the role of epigenetic modifications in cancer as well as in constitutional diseases. We will focus on mental impairment because of the growing evidence for the contribution of epigenetics in memory formation and cognition. Disturbance of the epigenetic profile due to direct alterations at genomic regions, or failure of the epigenetic machinery due to genetic mutations in one of its components, has been demonstrated in cognitive derangements in a number of neurological disorders now. It is therefore tempting to speculate that the cognitive deficit in a significant percentage of patients with unexplained mental retardation results from epigenetic modifications.

  2. Simultaneous determination of brominated and phosphate flame retardants in flame-retarded polyester curtains by a novel extraction method.

    Science.gov (United States)

    Miyake, Yuichi; Tokumura, Masahiro; Nakayama, Hayato; Wang, Qi; Amagai, Takashi; Ogo, Sayaka; Kume, Kazunari; Kobayashi, Takeshi; Takasu, Shinji; Ogawa, Kumiko; Kannan, Kurunthachalam

    2017-12-01

    The use of novel brominated flame retardants (BFRs) and phosphate-based flame retardants (PFRs) has increased as substitutes for hexabromocyclododecane (HBCD) in many consumer products. To facilitate collection of data on chemicals used as flame retardants in textiles and fabrics, we developed an analytical method using liquid chromatography interfaced with tandem mass spectrometry (LC-MS/MS). We compared two extraction methods, one involving ultrasonic extraction (traditional method) using dichloromethane, toluene or acetone and the other encompassing complete dissolution of textile with 25% 1,1,1,3,3,3-hexafluoro-2-propanol/chloroform. The dissolution method extracted up to 204 times more BFRs and PFRs than the traditional ultrasonic extraction. Tris(2,3-dibromopropyl) isocyanurate (TDBP-TAZTO), triphenylphosphine oxide (TPhPO), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), tricresyl phosphate (TCsP), and triphenyl phosphate (TPhP) were found in 40 flame-retarded curtain samples purchased from Japanese market in 2014. TDBP-TAZTO was detected in polyester curtains for the first time. Some of the flame-retarded curtain samples did not contain any of the known target analytes, which suggested the presence of other unknown flame retardants in those fabrics. Copyright © 2017. Published by Elsevier B.V.

  3. Hierarchical Polyphosphazene@Molybdenum Disulfide Hybrid Structure for Enhancing the Flame Retardancy and Mechanical Property of Epoxy Resins.

    Science.gov (United States)

    Zhou, Xia; Qiu, Shuilai; Xing, Weiyi; Gangireddy, Chandra Sekhar Reddy; Gui, Zhou; Hu, Yuan

    2017-08-30

    A novel polyphosphazene (PZS) microsphere@molybdenum disulfide nanoflower (MoS2) hierarchical hybrid architecture was first synthesized and applied for enhancing the mechanical performance and flame retardancy of epoxy (EP) resin via a cooperative effect. Herein, using PZS microsphere as the template, a layer of MoS2 nanoflowers were anchored to PZS spheres via a hydrothermal strategy. The well-designed PZS@MoS2 exhibits excellent fire retardancy and a reinforcing effect. The obtained PZS@MoS2 significantly enhanced the flame-retardant performance of EP composites, which can be proved by thermogravimetric and cone calorimeter results. For instance, the incorporation of 3 wt % PZS@MoS2 brought about a 41.3% maximum reduction in the peak heat-release rate and decreased by 30.3% maximum in the total heat release, accompanying the higher graphitized char layer. With regard to mechanical property, the storage modulus of EP/PZS@MoS23.0 in the glassy state was dramatically increased to 22.4 GPa in comparison with that of pure EP (11.15 GPa). It is sensible to know that the improved flame-retardant performance for EP composites is primarily assigned to a physical barrier effect of the MoS2 nanoflowers and the polyphosphazene structure has an positive impact on promoting char formation in the condensed phase.

  4. Novel routes in flame retardancy of bisphenol A polycarbonate/impact modifier/aryl phosphate blends

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzyn, Eliza

    2013-07-01

    The massive use of electronic engineering products accompanied by high demands on fire safety has led to increasing interest in environmentally friendly flame retardancy of bisphenol A polycarbonate (PC) based materials. In this work, novel routes for enhancing the flame retardancy of PC/Impact Modifier/Aryl phosphate were studied with respect to pyrolysis (TG, TG-FTIR, ATR-FTIR, NMR), flammability (LOI and UL 94) and fire behavior (cone calorimeter at different irradiations). To improve charring of PC/ABS{sub PTFE}+Aryl phosphate, the exchange of bisphenol A bis(diphenyl phosphate) (BDP) with novel aryl phosphates was proposed. Two novel flame retardants were synthesized: 3,3,5-trimethylcyclohexylbisphenol-bis(diphenyl phosphate) (TMC-BDP) and bisphenol A-bis(diethylphosphate) (BEP). TMC-BDP was more stable than BDP, thus gave a potential to increase the chemical reactions between the components of the PC/ABS{sub PTFE}+Aryl phosphate, whereas more reactive BEP was expected to increase the cross linking activity with the polymer matrix. Nevertheless, the corresponding blends did not enhance the flame retardancy compared to PC/ABS{sub PTFE}+BDP. BEP in PC/ABS{sub PTFE} preferred to cross-link with itself instead of with PC, thus it showed poor fire protection performance. TMC-BDP gave as good results as BDP in PC/ABS PTFE material. The results delivered evidence that BDP possesses a high degree of optimization in PC/ABS{sub PTFE} system. To provide a novel impact modifier improving not only mechanical properties but also the fire retardancy of PC/BDP material, the replacement of highly flammable acrylonitrile-butadiene-styrene (ABS) with silicon acrylate rubber (SiR) with high content of polydimethylsiloxane (PDMS) was studied. In PC/SiR{sub PTFE}/BDP the replacement of ABS is beneficial, but PDMS worsened the BDP gas phase and condensed phase action. PDMS reacted also with PC during combustion. PDMS-PC and PDMS-BDP interactions led to silicon dioxide. In fact, the

  5. The third international interlaboratory study on brominated flame retardants

    Energy Technology Data Exchange (ETDEWEB)

    Boer, J. de [Netherlands Institute for Fisheries Research, IJmuiden (Netherlands); Wells, D. [FRS Marine Laboratory, Aberdeen (United Kingdom)

    2004-09-15

    Polybrominated diphenyl ethers (PBDEs) have been produced as brominated flame retardants (BFRs) since the early 1970s and have been found in the aquatic environment since the late 1970s. However, as a result of their detection in sperm whales from deeper Atlantic waters and in human milk, many laboratories are now measuring PBDEs in environmental samples. A first international interlaboratory study (ILS) on the analysis of PBDEs, organised by the Bromine Science and Environmental Forum (BSEF), Brussels, Belgium, in collaboration with the Netherlands Institute for Fisheries Research (RIVO) was conducted in 1999-2000. The results showed that the 18 participating laboratories produced comparable results for BDE 47 in various matrices but had analytical difficulties for other BDEs, in particular for the BDEs 99 and 209. A second study was organised in 2001-2002 by BSEF, QUASIMEME and RIVO. That study showed improvement in comparability of the participating laboratories for BDE99 and some other BDEs. However, there was no improvement for BDE209. Hexabromocyclododecane (HBCD), tetrabromobisphenol-A (TBBP-A) and the dimethyl derivative of TBBP-A (dimethyl TBBP-A) were included in the second study. However, it appeared that only two or three laboratories were able to analyse these determinands. Others laboratories were still in the development phase with their methods for these BFRs. This third study was organised as a development exercise by QUASIMEME, in collaboration with RIVO between September and December 2003. The BFRs selected were the same as in the second study. Two biota test materials, a harbor sediment, a sewage sludge, and two standard solutions were dispatched to the participants.

  6. Duplication of 5q21 in a mildly retarded male and his non-retarded mother

    Energy Technology Data Exchange (ETDEWEB)

    Stallard, R.; Zurcher, V.; Schwartz, S. [Case Western Reserve Univ., Cleveland, OH (United States)

    1994-09-01

    Euchromatic autosomal additions to chromosomal complements are typically associated with global effects including mental retardation (MR) and dysmorphism. We report a familial duplication that does not appear to cause consistent, significant effects. A hyperactive male with mild MR was referred for fra(X) testing at 8 yrs. His karyotype was fra(X) negative and normal except for an addition in one 5q. The abnormal 5 was also in the maternal karyotype, but all other parental chromosomes were normal. The addition (=8.5% the length of a 5) was interpreted as a duplication of band 5q21. FISH with Coatasome 5 (Oncor) showed the addition was from 5. The proband`s karyotype was designated 46,XY,dup(5)(q15q22.1)mat; his mother`s, 46,XX,dup(5)(q15q22.1). Single copy probes are being used to test the cytogenetic interpretation. At 39 yrs, the non-retarded, somewhat inattentive mother, who has a high school diploma and subsequent secretarial courses, cares for the proband and his chromosomally normal, but learning disabled sister at home. The family situation is chaotic with reported paternal psychiatric illness and abuse of the proband and his sister. The mother`s father is dead, but her four younger siblings and mother are reportedly normal. Their chromosomes have not been available. The proband was born at 40 weeks following an uneventful pregnancy, with length and weight at the 5-10th centiles. He walked and talked at about one year. At 9 yrs, his ht/wt ratio was 10th centile. Foot length as <3rd centile; soft masses were present on the anterior ankles. He was otherwise physically normal. His estimated I.Q. was 75 and he was severely hyperactive despite Ritalin. This is the first report of a familial duplication in 5q; no identical, isolated case is known. Although additional family members need evaluation, the presence of the dup(5q) in the non-retarded mother suggests that it may not be associated with the proband`s MR.

  7. Flame Retardancy of Carbon Fibre Reinforced Sorbitol Based Bioepoxy Composites with Phosphorus-Containing Additives

    Directory of Open Access Journals (Sweden)

    Andrea Toldy

    2017-04-01

    Full Text Available Carbon fibre reinforced flame-retarded bioepoxy composites were prepared from commercially available sorbitol polyglycidyl ether (SPE cured with cycloaliphatic amine hardener. Samples containing 1, 2, and 3% phosphorus (P were prepared using additive type flame retardants (FRs resorcinol bis(diphenyl phosphate (RDP, ammonium polyphosphate (APP, and their combinations. The fire performance of the composites was investigated by limiting oxygen index (LOI, UL-94 tests, and mass loss calorimetry. The effect of FRs on the glass transition temperature, and storage modulus was evaluated by dynamic mechanical analysis (DMA, while the mechanical performance was investigated by tensile, bending, and interlaminar shear measurements, as well as by Charpy impact test. In formulations containing both FRs, the presence of RDP, acting mainly in gas phase, ensured balanced gas and solid-phase mechanism leading to best overall fire performance. APP advantageously compensated the plasticizing (storage modulus and glass transition temperature decreasing effect of RDP in combined formulations; furthermore, it led to increased tensile strength and Charpy impact energy.

  8. Responses of tooth eruption and alveolar bone subject to somatic growth retardation in the rat.

    Science.gov (United States)

    Park, A W

    1981-06-01

    The morphogenesis and regression of the osteodental fissure formed by alveolar bone in the maxillary and mandibular regions has been investigated in relation to eruption of the dentition during and following a period of somatic retardation stemming from nutritional suppression. Fissural formation occurred above the first and second molars of the maxilla and mandible, morphologically within normal limits but retarded by two days. During eruption a sequence of cuspal perforations of the alveolar bone took place behind the edge of the alveolar crest which later disintegrated as the bulk of the crown moved upwards. The appearance of the specific cusps of the experimental animals was two days behind that of the controls. Eruption through the oral mucosa was fairly rapid and the deficit noted in the bone emergence phase was reduced to one day. As in control animals, fissural formation did not occur over the third molars which were totally encapsulated by bone. Eruption of third molars in experimental animals was similar to control observations- no difference in timing and the removal of the encapsulating bone being achieved by the rapid enlarging of a wedge-shaped area at the mesio-occlusal aspect. Observation of eruption through alveolar bone is regarded as a more accurate assessment of changes in the early phases.

  9. Surface Modification of Fire-retardant Asphalt with Silane Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    CHEN Huiqiang; TANG Boming

    2012-01-01

    The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced,The optimum silane dosage was determined,and the structure and properties of the asphalt fire-retardant before and after the surface modification were characterized by infrared spectrum and thermo gravimetric analysis.The dispersion effect of asphalt fire-retardant was studied.The influence of the surface modification on the hydrophilicity and lipophilicity of the asphalt fire-retardant was analyzed.The experimental results showed that there were physical and chemical interactions between the silane coupling agent and the asphalt fire-retardant,which reduced the surface polarity of the asphalt fire retardant.The optimum silane coupling agent dosage was 0.95% of the asphalt fire retardant.The surface modification improved the thermal stability,dispersibility and lipophilicity of the asphalt fire retardant,which enhanced the compatibility between asphalt fire retardant and asphalt.

  10. Thermal properties of flame retardant cotton fabric grafted by dimethyl methacryloyloxyethyl phosphate

    Directory of Open Access Journals (Sweden)

    Xing Tie-Ling

    2012-01-01

    Full Text Available Thermal properties of flame retardant cotton fabric grafted by dimethyl methacryloy-loxyethyl phosphate were investigated by the atom transfer radical polymerization method. Thermal gravimetric analysis was used to explore the thermal decomposition mode of flamed retardant cotton fabric. The weight loss rate of the flamed retardant cotton was bigger than that of the control cotton fabric, and a more final residual char of flamed retardant cotton was also observed. Flammability tests were used to study the flame retardance property of the flame retardant cotton fabric. The results showed that flamed retardant cotton fabric with 16.8% of weight gain could keep good flame retardance. Scanning electron microscope pictures were applied to investigate the morphology of residual char of the flame retardant samples.

  11. THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

    Institute of Scientific and Technical Information of China (English)

    Qing-shan Kong; Bing-bing Wang; Quan Ji; Yan-zhi Xia; Zhao-xia Guo; Jian Yu

    2009-01-01

    Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride. The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry (TG), X-ray diffraction (XRD), limiting oxygen index (LOI) and cone calorimeter (CONE). The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34, and the heat release rate (HRR), total heat release (THR), CO and CO_2 concentrations during combustion are much lower compared with those of viscose fibers. Calcium carbonate and calcium oxide were formed during thermal degradation of calcium alginate fibers at different temperatures. The shape of calcium alginate fibers is well kept after LOI test. The rigid combustion residue char acts as an effective barrier to the outward diffusion of flame and heat. The combustion process and flame retardant mechanism of calcium alginate fibers are also discussed.

  12. Flame Retardant and Antimicrobial Jute Textile Using Sodium Metasilicate Nonahydrate

    Directory of Open Access Journals (Sweden)

    Basak S.

    2014-06-01

    Full Text Available Flame retardant and antimicrobial functionalities were imparted in jute textile using sodium metasilicate nonahydrate (SMSN, commonly known as “water glass”. Sodium metasilicate nonahydrate (SMSN was applied in jute fabric in different concentration by padding method followed by drying. Flame retardancy of the fabric was evaluated by Limiting Oxygen Index (LOI and burning behaviour under vertical flammability tester including the char length. Burning rate was found to decrease by almost 10 times after an application of 2% SMSN compared to the control sample. Thermogravimetry (TG and differential scanning calorimetry (DSC analysis of both the control and treated jute fabrics were utilized to understand the mechanism of developed flame retardance in jute fabric. It was observed that the SMSN treated samples showed excellent antimicrobial property against both gram positive and gram negative bacteria. Antimicrobial properties of both the control and treated jute fabrics were also measured quantitatively.

  13. Disease profile of 400 institutionalized mentally retarded patients in Kuwait.

    Science.gov (United States)

    Farag, T I; al-Awadi, S A; el-Badramary, M H; Aref, M A; Kasrawi, B; Krishna Murthy, D S; el-Khalifa, M Y; Yadav, G; Marafie, M J; Bastaki, L

    1993-12-01

    In this preliminary report we summarize the results of a 4-year multidisciplinary systematic, etiological clinicogenetic survey of 400 institutionalized mentally retarded patients in Kuwait. All had an intelligence quotient below 50. A constitutional disorder, as the direct cause of the mental retardation, was found in 203 patients (50.75%)): a chromosomal abnormality in 37 (9.25%), Mendelian disorders in 137 (34.25%), MCA/MR in 22 (5.55%) and CNS malformations in 7 cases (1.75%). In 157 patients (39.35%) a pre-, peri or postnatal cause was ascertained. No etiological diagnosis was detected in 40 patients (10%). A detailed analysis of the "disease profile" is given and compared with the results of previous diagnostic genetic surveys among different institutionalized mentally retarded populations in Western and developing countries.

  14. FLAMMABILITY OF ARALDITE BASED COMPOSITE MIXED WITH INORGANIC RETARDANTS

    Directory of Open Access Journals (Sweden)

    ALI I. AL-MOSAWI

    2012-10-01

    Full Text Available Flammability characteristics of araldite based composite mixed with inorganic hybrid flame retardant represent zinc borate - antimony trioxide as a surface layer(4mm thickness have been studied by thermal erosion test . Antimony trioxide was added to zinc borate with various amounts (10%,20% and 30% to forming a hybrid flame retardant for enhance the action of this material to react flame . The result composite material was exposed to a direct flame generated from Oxyacetylene torch (3000ºC with different flame exposure intervals (10,20mm, and studies the range of resistance of retardant material layer to the flames and protected the substrate. The optimum results were with large percentage from protective layer which is zinc borate-30% antimony trioxide and large exposed distance.

  15. Brominated flame retardant: environmental and exposed individuals' health impact.

    Science.gov (United States)

    Dufour, Patrice; Charlier, Corinne

    2017-04-01

    Since Antiquity, men have used chemicals to protect their goods against fire. Effective and easy to use, brominated flame retardants are used since decades massively in plastic industry. Such like other organohalogenated compounds, brominated flame retardants are very persistent in the environment and able to accumulate along the food chain. Many authors highlight their presence in the environment, in many animal species and in the human serum. Worryingly, man is exposed as soon as the pregnancy and then by the breastfeeding. This exposition may have consequence on our health. Many studies (in vitro, in vivo or epidemiologic) highlight brominated flame retardant negative effects on the endocrine system, mainly on the thyroid function but also on the reproduction, the neurodevelopment in the children and on the metabolism with increasing diabetes risk. If authorities and some big enterprises are aware about the problematic, new studies are needed to confirm previous results, elucidate endocrine disrupting mechanisms and highlight hypothetical synergies with other pollutants such like PCBs.

  16. PLACENTAL PATHOLOGY IN INTRA UTERINE GROWTH RETARDATION

    Directory of Open Access Journals (Sweden)

    Vijaya Sheela

    2015-04-01

    Full Text Available INTRODUCTION: The placental development is an essential step in developing effective strategies or the prediction of various maternal and fetal medical and developmental problems . Oxygen transfer and nutrients to the fetus will be actively regulated by the placenta . AIM AND OBJECTIVE: To study morphological changes of placenta in Intrauterine growth Retardation and to correlate morphological changes of placenta with fetal outcome . MATERIALS AND METHODS: Placental tissue samples were obtained from 50 pregnancies complicated by IUGR and 50 normal uncomplicated pregnancies with gestational age between 28 to 42 weeks attending King George hospital Visakhapatnam . INCLUSIVE CRITERIA : An IUGR fetuses whose estimated fetal weight less than those in 10 th percentile are included in the study . Birth weight percentiles were determined by previously published normal curves . EXCLUSIVE CRITERIA: fetuses with known syndromes , chromosomal anomalies and twins . For all patients included in the data set gestational age was estimated from the last menstrual period or early ultra - sonogram before the 12 th week of gestation . The final data set was composed of 50pregnancies complicated by IUGR and APGAR scores . Because preeclampsia is an important maternal factor associated with IUGR , these cases were further divided into t wo subgroups according to presence of hypertension . Samples were taken both from vaginal deliveries and caesarean sections . All the placentas were examined by pathologists . The placentas were weighed . For each case one or two samples from the umbilical cor ds , extra placental membrane , and parenchyma were taken . Gross pathological findings were confirmed by histology . Histological data included are ischemic necrosis , decidual vascularity , acute chorioamni oni tis , fibrinoid necrosis and choriangiosis . Appropriate statistical parameters were used . Chi - square test was conducted to compare placental pathological changes

  17. Sugar Supplementation Stimulates Growth Performance in Calves with Growth Retardation

    OpenAIRE

    Sato, Tomohiro; HIDAKA, Yuichi; KAMIMURA, Shunichi

    2010-01-01

    The growth effect of sugar supplementation was determined in 49 retarded growth calves. Calves were supplemented with sugar at 1 g/kg BW 2 times weekly for 8 weeks. Glucose tolerance tests prior to the experiment showed no difference between the retarded growth calves and normal growth controls. After sugar supplementation, the calves were classified into 4 groups characterized by high (H) or low (L) periodic changes in daily weight gain (DG) with a breakpoint of 0.8 kg/d in three periods, bi...

  18. Retardation effects in induced atomic dipole-dipole interactions

    CERN Document Server

    Graham, S D

    2016-01-01

    We present mean-field calculations of azimuthally averaged retarded dipole-dipole interactions in a Bose-Einstein condensate induced by a laser, at both long and short wavelengths. Our calculations demonstrate that dipole-dipole interactions become significantly stronger at shorter wavelengths, by as much as 30-fold, due to retardation effects. This enhancement, along with inclusion of the dynamic polarizability, indicate a method of inducing long-range interatomic interactions in neutral atom condensates at significantly lower intensities than previously realized.

  19. [Adults with mild mental retardation and intelligence tests].

    Science.gov (United States)

    Roivainen, Eka

    2015-01-01

    One of the criteria for mild mental retardation is a total level of less than 70 IQ points measured by an intelligence test. The results of intelligence tests are approximate. There are differences in the norms of test versions, and measurement error must be taken into account in individual testing. A total level of 80 measured by adult tests utilized in Finland does not exclude the possibility of mild mental retardation, and a total level of 60 does not confirm it. The test performance should be compared with other measures, such as school and work history, practical functional capacity and previous test results.

  20. THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

    Institute of Scientific and Technical Information of China (English)

    于建; 夏延致

    2009-01-01

    Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during ...

  1. Role-taking, moral development, and mental retardation.

    Science.gov (United States)

    Perry, J E; Krebs, D

    1980-03-01

    Role-taking ability and level of moral development were measured in three groups of boys and girls including 16 moderately retarded adolescents (mean chronological age 15; mean mental age 9), 16 nonretarded adolescents matched for chronological age, and 16 nonretarded children matched for mental age. The mentally retarded adolescents scored significantly lower on role-taking ability and moral development than the adolescents matched for chronological age. They did not differ from children of their same mental age in role-taking ability; and they tended to score lower in moral development. The results supplied qualified support for Kohlberg's theory of moral development.

  2. Background music for repetitive task performance of severely retarded individuals.

    Science.gov (United States)

    Richman, J S

    1976-11-01

    Environmental manipulation in the form of specific tempo background music was used to assist in the habilitation of severely retarded persons. Thirty institutionalized retarded males were tested on a repetitive manual performance task judged to be similar to the type of tasks found in sheltered workshops. Each subject received each of the background treatments noncontingently: no music, slow tempo music, regular tempo music, fast tempo music. The results indicated that the regular tempo of background music facilitated the greatest improvement in performance, suggesting that the effect of music on performance is more complex than the issue of contingent presentation.

  3. Point defect engineering strategies to retard phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-01-01

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

  4. Role of microRNA pathway in mental retardation.

    Science.gov (United States)

    Qurashi, Abrar; Chang, Shuang; Peng, Jin

    2007-11-02

    Deficits in cognitive functions lead to mental retardation (MR). Understanding the genetic basis of inherited MR has provided insights into the pathogenesis of MR. Fragile X syndrome is one of the most common forms of inherited MR, caused by the loss of functional Fragile X Mental Retardation Protein (FMRP). MicroRNAs (miRNAs) are endogenous, single-stranded RNAs between 18 and 25 nucleotides in length, which have been implicated in diversified biological pathways. Recent studies have linked the miRNA pathway to fragile X syndrome. Here we review the role of the miRNA pathway in fragile X syndrome and discuss its implication in MR in general.

  5. Fetishistic transvestism in a patient with mental retardation and psychosis.

    Science.gov (United States)

    Velayudhan, Rajmohan; Khaleel, Asfia; Sankar, Nideesh; Kumar, Manoj; Kazhungil, Firoz; Raghuram, Thazhe Mangool

    2014-04-01

    Fetishistic transvestism is a disorder of sexual preference associated with fantasies and sexual urges to dress in opposite gender clothing as a means of arousal and as an adjunct to masturbation and coitus. The disorder has been reported in people with learning disabilities. The disorder has been reported in a young male with dull normal intelligence. Transvestism though has been described in schizophrenia and psychosis and fetishism has been described in the course of simple schizophrenia, there are no reports of fetishistic transvestism in a patient with mental retardation and psychosis. A case of fetishistic transvestism in a patient with mental retardation and psychosis with treatment and relevant review of literature is reported.

  6. RETARDATION AS PART OF THE CONCEPTUALIZATION OF SUSTAINABLE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Ryszard Janikowski

    2014-10-01

    Full Text Available Category material and immaterial retardation is the canonical element of the strategy for the implementation of sustainable development. Earth's non-renewable environmental resources are limited and finite, not only in the local or regional context, they are finite and exhaustible also in a global context. It is necessary to slow down consumption of resources, and it means cultural change. Category material and immaterial retardation in view of the multi-dimensional needs further in-depth research and disseminating positive examples.

  7. Comparative studies on the retardation and reduction of glyphosate during subsurface passage.

    Science.gov (United States)

    Litz, N T; Weigert, A; Krause, B; Heise, S; Grützmacher, G

    2011-05-01

    The herbicide Glyphosate was detected in River Havel (Berlin, Germany) in concentrations between 0.1 and 2 μg/L (single maximum outlier: 5 μg/L). As the river indirectly acts as drinking water source for the city's 3.4 Mio inhabitants potential risks for drinking water production needed to be assessed. For this reason laboratory (sorption and degradation studies) and technical scale investigations (bank filtration and slow sand filter experiments) were carried out. Batch adsorption experiments with Glyphosate yielded a low K(F) of 1.89 (1/n = 0.48) for concentrations between 0.1 and 100 mg/L. Degradation experiments at 8 °C with oxygen limitation resulted in a decrease of Glyphosate concentrations in the liquid phase probably due to slow adsorption (half life: 30 days). During technical scale slow sand filter (SSF) experiments Glyphosate attenuation was 70-80% for constant inlet concentrations of 0.7, 3.5 and 11.6 μg/L, respectively. Relevant retardation of Glyphosate breakthrough was observed despite the low adsorption potential of the sandy filter substrate and the relatively high flow velocity. The VisualCXTFit model was applied with data from typical Berlin bank filtration sites to extrapolate the results to a realistic field setting and yielded sufficient attenuation within a few days of travel time. Experiments on an SSF planted with Phragmites australis and an unplanted SSF with mainly vertical flow conditions to which Glyphosate was continuously dosed showed that in the planted SSF Glyphosate retardation exceeds 54% compared to 14% retardation in the unplanted SSF. The results show that saturated subsurface passage has the potential to efficiently attenuate glyphosate, favorably with aerobic conditions, long travel times and the presence of planted riparian boundary buffer strips.

  8. Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2017-01-01

    Full Text Available In order to comprehensively improve the strength, toughness, flame retardancy, smoke suppression, and thermal stability of polypropylene (PP, layered double hydroxide (LDH Ni0.2Mg2.8Al–LDH was synthesized by a coprecipitation method coupled with the microwave-hydrothermal treatment. The X-ray diffraction (XRD, morphology, mechanical, thermal, and fire properties for PP composites containing 1 wt %–20 wt % Ni0.2Mg2.8Al–LDH were investigated. The cone calorimeter tests confirm that the peak heat release rate (pk–HRR of PP–20%LDH was decreased to 500 kW/m2 from the 1057 kW/m2 of PP. The pk–HRR, average mass loss rate (AMLR and effective heat of combustion (EHC analysis indicates that the condensed phase fire retardant mechanism of Ni0.2Mg2.8Al–LDH in the composites. The production rate and mean release yield of CO for composites gradually decrease as Ni0.2Mg2.8Al–LDH increases in the PP matrix. Thermal analysis indicates that the decomposition temperature for PP–5%LDH and PP–10%LDH is 34 °C higher than that of the pure PP. The mechanical tests reveal that the tensile strength of PP–1%LDH is 7.9 MPa higher than that of the pure PP. Furthermore, the elongation at break of PP–10%LDH is 361% higher than PP. In this work, the synthetic LDH Ni0.2Mg2.8Al–LDH can be used as a flame retardant, smoke suppressant, thermal stabilizer, reinforcing, and toughening agent of PP products.

  9. Predicting Adaptive Functioning of Mentally Retarded Persons in Community Settings.

    Science.gov (United States)

    Hull, John T.; Thompson, Joy C.

    1980-01-01

    The impact of a variety of individual, residential, and community variables on adaptive functioning of 369 retarded persons (18 to 73 years old) was examined using a multiple regression analysis. Individual characteristics (especially IQ) accounted for 21 percent of the variance, while environmental variables, primarily those related to…

  10. "School Retardation" in Mexico from 1920 to 1960: Conceptual Passages

    Science.gov (United States)

    Castro, Josefina Granja

    2012-01-01

    Educational concepts, such as enrolment, attendance, passing or failing students, school retardation, and school desertion, which made it possible to describe the course of children through the school system, went through a gradual process, beginning in the second half of the nineteenth century and throughout the first decades of the twentieth. In…

  11. Music Training for Severely and Profoundly Retarded Individuals.

    Science.gov (United States)

    Kesler, Buford; Richmond, Bert O.

    Investigated were the effects of sex, ability and training method on the musical instrument playing ability of 16 institutionalized severely and profoundly retarded persons ages 7 to 20 years. Ss were randomly assigned to one of four treatment groups, and the time required to reach criterion playing a familiar tune was recorded. Data indicated…

  12. Japanese Studies on Attitudes towards Persons with Mental Retardation.

    Science.gov (United States)

    Tachibana, Toshiaki; Watanabe, Kanji

    2002-01-01

    Review of Japanese studies on attitudes toward persons with mental retardation first notes origins in increased support for special classes in schools. Reported findings focus on items most affecting attitude differences, gender differences, effect of contact, educational differences, and age differences. A unique sociological study in a fishery…

  13. PHENYLKETONURIA, AN INHERITED METABOLIC DISORDER ASSOCIATED WITH MENTAL RETARDATION.

    Science.gov (United States)

    CENTERWALL, WILLARD R.; CENTERWALL, SIEGRIED A.

    ADDRESSED TO PUBLIC HEALTH WORKERS AND PHYSICIANS IN GENERAL PRACTICE, THE PAMPHLET INTRODUCES METHODS OF DETECTING AND MANAGING PHENYLKETONURIA, AN INHERITED METABOLIC DISORDER ASSOCIATED WITH MENTAL RETARDATION. INFORMATION, UPDATED FROM THE 1961 EDITION, IS INCLUDED ON THE INCIDENCE AND GENETICS, BIOCHEMISTRY, AND CLINICAL COURSE OF THE…

  14. Space for the Mentally Retarded in South Dakota. Final Report.

    Science.gov (United States)

    South Dakota State Dept. of Health, Pierre. Mental Retardation Planning Office.

    The 10 priority recommendations for aiding the mentally retarded in South Dakota are presented. Summaries are provided of recommendations for federal and state legislative action and for state agencies, communities, state medical and hospital associations, and private organizations. The State and the method of planning are discussed; mental…

  15. Mental Retardation FY 1983. Special Report to Congress.

    Science.gov (United States)

    National Inst. of Child Health and Human Development (NIH), Bethesda, MD.

    The paper reviews mental retardation research activities of the National Institute of Child Health and Human Development (NICHHD) and the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS). Research activities are cited to illustrate the scope of NICHHD's efforts in a variety of biomedial areas. Activities are…

  16. Services and Provisions for Persons with Mental Retardation in Sweden.

    Science.gov (United States)

    Melin, Lennar

    1988-01-01

    This paper focuses on recent legislation providing special services and provisions for mentally retarded persons in Sweden. The paper describes the legislation's goal in normalizing their lives, the types of residential placements available, their educational and vocational activities, and their mental health problems. (JDD)

  17. Molecular Genetic Approaches to Human Diseases Involving Mental Retardation.

    Science.gov (United States)

    Latt, Samuel A.; And Others

    1984-01-01

    Recombinant DNA techniques provide new approaches to the diagnosis and analysis of inherited human diseases associated with mental retardation, such as Lesch-Nyhan syndrome, phenylketonauria, the Fragile X syndrome, Down syndrome, and those associated with deletions or duplications of subchromosomal regions. (Author/CL)

  18. An Annotated Bibliography on the Severely and Profoundly Mentally Retarded.

    Science.gov (United States)

    Cass, Michael, Comp.; Schilit, Jeffrey, Comp.

    Presented is an annotated bibliography with approximately 250 entries relating to the severely and profoundly retarded. Citations are listed alphabetically by author under the following categories: assessments, measurements, evaluations; associations; attending behavior; behavior modification; books; classical conditioning; cognitive development;…

  19. The Psychopathological Model of Mental Retardation: Theoretical and Therapeutic Considerations.

    Science.gov (United States)

    La Malfa, Giampaolo; Campigli, Marco; Bertelli, Marco; Mangiapane, Antonio; Cabras, Pier Luigi

    1997-01-01

    Describes a new integrated bio-psycho-social model of etiology for mental retardation. Discusses the problems with current models and the ability of the "universe line" model to integrate data from different research areas, especially cognitive and psychopathologic indicators. Addresses implications of this theoretical approach. (Author/CR)

  20. Synergistic Study on the Effect of Flame Retardants on Timber

    Directory of Open Access Journals (Sweden)

    Nwajiobi, C.C

    2015-12-01

    Full Text Available the fire characteristic proportion of Halleacilliata has been carried out. The timber was treated with different concentrations of ammonium chloride (0.01, 0.05, 0.10, 0.15, 0.50, and 0.55 mol/dm3 and borax (0.01, 0.03, 0.05, 0.07, 0.10, and 0.12 mol/dm3 . Flammability tests such as ignition time, flame propagation rate and after-glow time were carried out and the results showed that the flame retardants drastically reduced the flame propagation rate and after-glow time while ignition time and percentage add-on (% increased. Synergy was observed when the two flame retardants were mixed at different concentrations which gave better retarding properties than when treated individually. These results are interpreted as arising from the fact that on heating, these flame retardants evolve molecules that interfere with the chemistry and pyrolysis of combustion of timber.

  1. A Training Model for Peer Tutoring with Mentally Retarded Individuals.

    Science.gov (United States)

    Vacc, Nicholas

    A program in which mentally retarded persons are trained to tutor their peers is described. Considered are selection and training aspects of such a program, and emphasized is the importance of the relationship between tutor and student. Tutors are explained to learn principles of establishing specific plans and keeping basic records. (CL)

  2. Oral Health of Institutionalized Individuals with Mental Retardation.

    Science.gov (United States)

    Jurek, George H.; Reid, William H.

    1993-01-01

    Residents (n=702) of Texas Department of Mental Health and Mental Retardation institutions were given dental examinations, and findings were compared with data from 1,077 residents 9 years earlier. Data were analyzed for oral pathology, unmet dental needs, contribution of dental care to habilitation, and effectiveness of the dental service system.…

  3. Estimation of Energy Stores of Mentally Retarded Individuals.

    Science.gov (United States)

    Litchford, Mary Demarest

    1987-01-01

    The study sought to identify reliable measurements for estimating energy stores of retarded adults (N=80) and possible correlations between energy intakes and obesity. Among results were a lack of significant correlations between caloric intake and anthropometric measures (e.g., tricepts skinfold). Body mass index is suggested as a more practical…

  4. Relationships between Facial Discrimination and Social Adjustment in Mental Retardation

    Science.gov (United States)

    Rojahn, Johannes; Esbensen, Anna J.; Hoch, Theodore A.

    2006-01-01

    Sixty-two adults with mental retardation of heterogeneous etiology performed four facial emotion discrimination tasks and two facial nonemotion tasks. Staff members familiar with the participants completed measures of social adjustment (the Socialization and Communication domains of the Vineland Adaptive Behavior Scales and the Social Performance…

  5. Maturational Rate of Tokyo Children with and without Mental Retardation.

    Science.gov (United States)

    Lindgren, Gunilla W.; Katoda, Hiroshi

    1993-01-01

    Comparison of growth rates and menarcheal age for groups of boys and girls, ages 6 to 15, in Tokyo (Japan) found that children with mental retardation had a smaller growth spurt during puberty but did not differ in maturational rate defined by age at pubertal height spurt or age at menarche. (Author/DB)

  6. Quantitative Assessments of Sensitivity to Reinforcement Contingencies in Mental Retardation.

    Science.gov (United States)

    Dube, William V.; McIlvane, William J.

    2002-01-01

    Sensitivity to reinforcement contingencies was examined in six individuals with mental retardation using a concurrent operants procedure in the context of a computer game. Results included individual differences in sensitivity and differential sensitivity to rate and magnitude variation. Results suggest that comprehensive assessments of potential…

  7. Drug Abuse in Persons with Mental Retardation: A Review.

    Science.gov (United States)

    Christian, LeeAnn; Poling, Alan

    1997-01-01

    Review of the literature on drug abuse by people with mental retardation addresses prevalence, drug-related problems, special vulnerabilities of this population, treatment programs, and status of drug abuse prevention and drug education for this population. A lack of and need for controlled research dealing with the genesis, treatment, and…

  8. Individuals with Mental Retardation from the Perspective of Turkish People

    Science.gov (United States)

    Güner Yildiz, Nevin

    2015-01-01

    This descriptive study examined the attitude of Turkish people towards the mentally retarded. The working group was composed of 329 male and female staff in various places of employment in Eskisehir provincial center, 87 non-working women living in Eskisehir provincial center and 49 non-working women living in Mugla provincial center. Research…

  9. Depressive Symptoms Displayed by Persons with Mental Retardation: A Review.

    Science.gov (United States)

    Pawlarcyzk, Douglas; Beckwith, Bill E.

    1987-01-01

    The applicability of the "Diagnostic and Statistical Manual of Mental Disorders III" diagnostic criteria for "Major Depressive Episode" within a population of persons with mild and moderate mental retardation was validated by reviewing reports of severe depression among these individuals. (Author/DB)

  10. Sexual Health and Behavior of Mentally Retarded Pupils in Japan

    Science.gov (United States)

    Tsutsumi, Angela Aparecida

    2009-01-01

    Sex education has always been a controversial topic. Although sex education at schools has improved in general, sex education for mentally retarded pupils still encounters prejudice and conservatism as a result of several misconceptions about the subject. This research was performed in the form of a survey of opinions about sex education in…

  11. Preliminary Study of Imipramine in Profoundly Retarded Residents.

    Science.gov (United States)

    Aman, Michael G.; And Others

    1986-01-01

    The effects of imipramine were assessed in 10 profoundly retarded subjects (aged 8-25 years) who exhibited either depressionlike symptoms or acting out behaviors. Results of observation, interval sampling, and the Aberrant Behavior Checklist indicated behavioral deterioration on irritability, lethargy/social withdrawal, and hyperactivity…

  12. Issues in Mental Health Counseling with Persons with Mental Retardation.

    Science.gov (United States)

    Prout, H. Thompson; Strohmer, Douglas C.

    1998-01-01

    Reviews mental-health issues concerning persons with mental retardation, particularly as these issues apply to mental-health counseling. Included in this review is a discussion of the prevalence of psychopathology, types of problems presented, issues in clinical bias, access to community services, assessment techniques, and specific…

  13. Functional Assessment of Problem Behaviors in Adults with Mental Retardation

    Science.gov (United States)

    Paclawskyj, Theodosia R.; Kurtz, Patricia F.; O'Connor, Julia T.

    2004-01-01

    Functional assessment has significantly improved the success of behavioral treatment of problem behaviors in adults with mental retardation. Functional assessment methods (i.e., techniques that yield a hypothesis of functional relationships) include direct observation, interviews, and checklists. Functional analysis consists of empirical methods…

  14. Fluid-Structure Interaction Using Retarded Potential and ABAQUS

    Science.gov (United States)

    1992-08-19

    but require the formuation and factoring of a global stiffness matrix. This is very costly and even prohibitive especially for Manuacript approved...Dimensional Retarded Potential Fluid - Finite Element Structural Analysis, NRL Memorandum, Report 5903, May 1987. 20. Tamm. M. A., A Parametric Patch

  15. OCCUPATIONAL INFORMATION FOR THE MENTALLY RETARDED, SELECTED READINGS.

    Science.gov (United States)

    STAHLECKER, LOTAR V., ED.

    INTENDED AS A REFERENCE TOOL FOR PROFESSIONAL PERSONS, THIS COMPILATION CONTAINS 78 ARTICLES SELECTED FOR THEIR PERTINENCE TO OCCUPATIONAL EDUCATION FOR MENTALLY RETARDED YOUTH AND ADULTS. THE ARTICLES ARE GROUPED INTO SIX MAJOR AREAS. ON GUIDANCE, 22 ARTICLES COVER THE TRANSITION FROM HIGH SCHOOL TO WORK, COUNSELING, EVALUATION OF WORK POTENTIAL,…

  16. Innovative green technique for preparing of flame retardant cotton

    Science.gov (United States)

    Due to its environmentally benign character, microwave-assisted or supercritical carbon dioxide high pressure reactors are considered in green chemistry as a substitute for organic solvents in chemical reactions. In this paper, an innovative approach for preparation of flame retardant cotton fabric ...

  17. Polysiloxane-Based Organoclay Nanocomposites as Flame Retardants

    Science.gov (United States)

    2013-01-01

    density polyethylene- nanoclay composites: The effect of poly ( acrylic acid ) on mechanical properties , XRD, morphology properties and water absorption...exhibited enhanced FR properties relative to copolye- sters and copolyamides[3–5]. The thermal studies suggested that the polyamic acid portion of...RETARDANT THERMAL PROPERTIES COPOLYMERS DECOMPOSITION THERMOGRAVIMETRIC ANALYSIS TEMPERATURE

  18. IQ and the Death Penalty: Verifying Mental Retardation.

    Science.gov (United States)

    Keyes, Denis William

    Whether or not subjects can simulate mental retardation, a consideration that has implications in criminal cases, was studied using 21 adult Caucasian males between 20 and 30 years of age, largely comprised of students and staff employees of the University of New Mexico. Subjects were asked to give genuine and simulated responses to two major test…

  19. A Note on Left-Handedness and Severity of Mental Retardation

    Science.gov (United States)

    Hicks, Robert E.; Barton, A. Keith

    1975-01-01

    This paper presents data supplementing previous reports of elevated incidence of left handedness for the mentally retarded. The new data confirm a positive relationship between degree of retardation and incidence of left-handedness. (GO)

  20. [Behavioral disorders and substance abuse in adolescents with mental retardation].

    Science.gov (United States)

    Papachristou, Ec; Anagnostopoulos, Dk

    2014-01-01

    The percentage of people with mental retardation in the general population is estimated at about 2.3%, with adolescence (15-20 years) constituting the development period during which a peak in rates of mental retardation is observed. The increased prevalence of adolescence may be explained from the fact that the specified requirements of the school initially, and society later, inevitably lead to comparative evaluation of the teen with mental retardation in relation to peers, thus making mental retardation more apparent. Adolescents with mental retardation face a number of physical and psychological needs which are not often distinguishable and as a consequence undergo the deterioration of their already burdened quality of life. In particular, mental health problems occur 3 to 4 times more often in adolescents with mental retardation compared with adolescents of the general population. This review presents the most recent epidemiological findings regarding the correlation between behavioral disorders, substance use and the possible comorbidity in adolescents with intellectual disability, both at community level and residential care level. Epidemiological data indicate that behavioral disorders are among the most common types of psychopathology in mentally retarded adolescents with the severity and symptoms varying depending on the personal characteristics of each adolescent. Regarding substance use, the available data show that the rates of substance use (alcohol, smoking, illicit drugs) are lower in this specific population group but the differences over the last years tend to be eliminated. Finally, according to the few surveys that were examined referring to the comorbidity of behavioral disorders and substance use in adolescents with intellectual disability, the results were contradictory. Specifically, while behavioral disorders continued to be one of the most common types of psychopathology, the related substances disorders indicated lower rates compared to

  1. EFFECT OF SOME PLANT GROWTH REGULATORS WITH RETARDING ACTIVITY ON SPRING PEA FOR GRAIN

    Directory of Open Access Journals (Sweden)

    Tsenka ZHELYAZKOVA

    2012-12-01

    Full Text Available A field experiment was conducted at Trakia University - Stara Zagora to establish the effect of some growth retardants on morphological and productive parameters in spring pea for grain variety Bogatir. Three combined preparations: Trisalvit (phenylphthalamic acid + chlorocholine chloride + chlorophenoxyacetic acid +salicylic acid at doses of 300 and 400 сmз*ha-1; SM-21 (phenylphthalamic acid + chlorocholine chloride at doses of 300 and 400 сmз*ha-1 and PNSA-44 (phenylphthalamic acid + naphthaleneacetic acid + chlorophenoxyacetic acid at doses of 200 and 300 сmз*ha-1 were applied in the early growth phase of the plant up to a height of 15-20 cm. The study showed that the greatest reduction in the stem height (by 12.8% compared to untreated plants was achieved by applying SM-21 (400 сmз*ha-1. The application of growth regulators Trisalvit and SM-21 had no appreciable effect on the production of spring pea grain. Maximum values of yield structure components (number of pods and grain per plant, grain mass per plant and mass of 1000 grain and the yield were obtained after application of PNSA-44 (300 сmз*ha-1 - up to 5.6% (117.2 kg*ha-1 more grain than the control. The investigation of the influence of tested factors (retardant, dose and year demonstrated that the conditions of the year as a factor had the strongest effect on plant height and grain yield.

  2. Understanding the Mechanism of Action of Triazine-Phosphonate Derivatives as Flame Retardants for Cotton Fabric

    Directory of Open Access Journals (Sweden)

    Monique M. Nguyen

    2015-06-01

    Full Text Available Countless hours of research and studies on triazine, phosphonate, and their combination have provided insightful information into their flame retardant properties on polymeric systems. However, a limited number of studies shed light on the mechanism of flame retardancy of their combination on cotton fabrics. The purpose of this research is to gain an understanding of the thermal degradation process of two triazine-phosphonate derivatives on cotton fabric. The investigation included the preparation of diethyl 4,6-dichloro-1,3,5-triazin-2-ylphosphonate (TPN1 and dimethyl (4,6-dichloro-1,3,5-triazin-2-yloxy methyl phosphonate (TPN3, their application on fabric materials, and the studies of their thermal degradation mechanism. The studies examined chemical components in both solid and gas phases by using attenuated total reflection infrared (ATR-IR spectroscopy, thermogravimetric analysis coupled with Fourier transform infrared (TGA-FTIR spectroscopy, and 31P solid state nuclear magnetic resonance (31P solid state NMR, in addition to the computational studies of bond dissociation energy (BDE. Despite a few differences in their decomposition, TPN1 and TPN3 produce one common major product that is believed to help reduce the flammability of the fabric.

  3. Super flame-retardant lightweight rime-like carbon-phenolic nanofoam

    Science.gov (United States)

    Cheng, Haiming; Hong, Changqing; Zhang, Xinghong; Xue, Huafei; Meng, Songhe; Han, Jiecai

    2016-09-01

    The desire for lightweight nanoporous materials with high-performance thermal insulation and efficient anti-ablation resistance for energy conservation and thermal protection/insulation has greatly motivated research and development recently. The main challenge to synthesize such lightweight materials is how to balance the relationship of low thermal conductivity and flame retardancy. Herein, we propose a new concept of lightweight “rime-like” structured carbon-phenolic nanocomposites to solve this problem, where the 3D chopped network-structured carbon fiber (NCF) monoliths are incorporated with nanoporous phenolic aerogel to retain structural and functional integrity. The nanometer-scaled porous phenolic (NP) was synthesized through polymerization-induced phase separation and ambient pressure drying using phenolic resin (PR) solution as reaction source, ethylene glycol (EG) as solvent and hexamethylenetetramine (HMTA) as catalyst. We demonstrate that the as-prepared NCF-NP nanocomposite exhibits with a low density of 0.25–0.35 g/cm3, low thermal conductivity of 0.125 Wm‑1K‑1 and outstanding flame retardancy exceeding 2000 °C under arc-jet wind tunnel simulation environment. Our results show that the synthesis strategy is a promising approach for producing nanocomposites with excellent high-temperature heat blocking property.

  4. RING CHROMOSOME 13 SYNDROME IN AN ADULT MALE WITH MILD MENTAL RETARDATION

    OpenAIRE

    Matsuishi, Takesi; Millar, Anne; Yamaguchi, Tetsuaki; Endo, Keiko

    1997-01-01

    A case of ring 13 syndrome in an 18-year-old male is presented with particular focus on mental retardation. The clinical picture was characterized by mild mental retardation, microcephaly, large low set ears, a broad nasal bridge, epicanthus, micrognathia and short philtrum. A review of the literature with a focus on mental retardation concluded that descriptions of mental retardation were often unqualified and at times ambiguous. Furthermore, in contrast to the characteristic description of ...

  5. Health-related Physical Fitness in Children with Mental Retardation

    Directory of Open Access Journals (Sweden)

    Fazel Bazyar

    2014-12-01

    Full Text Available Human health is highly dependent on the condition of health-related physical fitness and particularly body composition. Adolescence is unique in this regard, especially when the adolescents are mentally retarded, about whom information on physical fitness is limited. Thus, the objective of this paper was to study the components of health-related physical fitness with emphasis on body composition and weight gain and loss in mentally retarded students of Roodbar. Statistical sample included 91 mentally retarded male students with mean age of 13.44±1.56, mean height of 167±6.97, and mean IQ of 68.7±7.8. Physical fitness components were assessed using modified Brockport Physical Fitness Test (BPFT including cardiovascular endurance, muscular strength, muscular endurance, flexibility, and body composition (by calculation of body mass index. The results indicated that in terms of body mass index, 40% of participants were underweight, 10% were overweight, and 10% were obese. In addition, body fat percentage was high in 11.9% of subjects and very high in 13% of them. The mean aerobic power of mentally retarded boys aged 12-14 was measured 31.5% (ml/kg/min, indicating 25% and 35% lower physical fitness, respectively, compared to their normal peers and the reference values. The present study revealed that a significant proportion of mentally retarded adolescents in Roodbar are suffering from either underweight or overweight. Moreover, their physical fitness in all components is not desirable compared to their normal peers.

  6. Koppitz errors on the Bender-Gestalt for adult retardates: normative data.

    Science.gov (United States)

    Andert, J N; Dinning, W D; Hustak, T L

    1976-04-01

    Normative data on the Koppitz developmental scoring system for the Bender-Gestalt test were derived from a sample which included 510 protocols of adult resident retardates. Percentile norms are presented on Koppitz error scores for three AAMD ranges of retardation based on WAIS IQs and two AAMD ranges of retardation based on Stanford-Binet IQs.

  7. Mineralisation and primary biodegradation of aromatic organophosphorus flame retardants in activated sludge

    NARCIS (Netherlands)

    Jurgens, S.S.; Helmus, R.; Waaijers, S.L.; Uittenbogaard, D.; Dunnebier, D; Vleugel, M; Kraak, M.H.S.; de Voogt, P.; Parsons, J.R.

    2014-01-01

    Halogen-free flame retardants (HFFRs), such as the aromatic organophosphorus flame retardants (OPFRs) triphenyl phosphate (TPHP), resorcinol bis(diphenylphosphate) (PBDPP) and bisphenol A bis(diphenylphosphate) (BPA-BDPP) have been proposed as potential replacements for brominated flame retardants i

  8. Increased Lead and Cadmium Burdens among Mentally Retarded Children and Children with Borderline Intelligence.

    Science.gov (United States)

    Marlowe, Mike; And Others

    1983-01-01

    The relationship between subtoxic metal levels and mild mental retardation and borderline intelligence was investigated through comparison of hair metal concentrations in 135 secondary students with mild retardation or borderline intelligence. Children in the retarded/borderline group had significantly higher lead and cadmium concentrations.…

  9. Neurotoxicity of past, present and future flame retardants - neurotoxic hazard characterization and risk assessment of (alternative) flame retardants

    NARCIS (Netherlands)

    Hendriks, H.S.

    2014-01-01

    Brominated flame retardants (BFRs), and to a lesser extent polychlorinated biphenyls (PCBs), are widely used chemicals that prevent or slow the onset and spreading of fire in order to reduce injuries and death. Unfortunately, many of these compounds pose serious threats for human health and the envi

  10. Part I. Improved flame retardant textiles. Part II. Novel approach to layer-by-layer processing for flame retardant textiles.

    Science.gov (United States)

    In this presentation, new approaches for flame retardant textile by using supercritical carbon dioxide (scCO2) and layer-by-layer processing will be discussed. Due to its environmentally benign character, the scCO2 is considered in green chemistry as a substitute for organic solvents in chemical re...

  11. Plasma-enhanced synthesis of green flame retardant cellulosic materials

    Science.gov (United States)

    Totolin, Vladimir

    The natural fiber-containing fabrics and composites are more environmentally friendly, and are used in transportation (automobiles, aerospace), military applications, construction industries (ceiling paneling, partition boards), consumer products, etc. Therefore, the flammability characteristics of the composites based on polymers and natural fibers play an important role. This dissertation presents the development of plasma assisted - green flame retardant coatings for cellulosic substrates. The overall objective of this work was to generate durable flame retardant treatment on cellulosic materials. In the first approach sodium silicate layers were pre-deposited onto clean cotton substrates and cross linked using low pressure, non-equilibrium oxygen plasma. A statistical design of experiments was used to optimize the plasma parameters. The modified cotton samples were tested for flammability using an automatic 45° angle flammability test chamber. Aging tests were conducted to evaluate the coating resistance during the accelerated laundry technique. The samples revealed a high flame retardant behavior and good thermal stability proved by thermo-gravimetric analysis. In the second approach flame retardant cellulosic materials have been produced using a silicon dioxide (SiO2) network coating. SiO 2 network armor was prepared through hydrolysis and condensation of the precursor tetraethyl orthosilicate (TEOS), prior coating the substrates, and was cross linked on the surface of the substrates using atmospheric pressure plasma (APP) technique. Due to protection effects of the SiO2 network armor, the cellulosic based fibers exhibit enhanced thermal properties and improved flame retardancy. In the third approach, the TEOS/APP treatments were extended to linen fabrics. The thermal analysis showed a higher char content and a strong endothermic process of the treated samples compared with control ones, indicating a good thermal stability. Also, the surface analysis proved

  12. Cardiac surgery for adults with mental retardation. Dilemmas in management.

    Science.gov (United States)

    Goldhaber, S Z; Reardon, F E; Goulart, D T; Rubin, I L

    1985-10-01

    In summary, cardiac surgery for adults with mental retardation raises a series of controversial legal, economic, ethical, medical, and nursing dilemmas. During the past 20 years, many improvements have taken place in the care of these patients. However, in the future, judicial and statutory mandates requiring high-quality medical care for persons with mental retardation may conflict increasingly with hospital cost-control legislation and thereby affect clinical decisions. For example, it is conceivable that elective repair of an ostium secundum atrial septal defect in an asymptomatic patient will expend the limited resources necessary to carry out emergency revascularization in a symptomatic patient with impending myocardial infarction. This issue becomes even more delicate when the asymptomatic patient is a mentally retarded ward of the state, and the symptomatic patient is a middle-aged man supporting a wife and several college-age children. There may be no easy solution to this problem, and it will provide the grist for many bioethicists. Fortunately, from a practical point of view, we do not currently have to choose between these patients to receive treatment. Our hope is that health care for mentally retarded patients will not be compromised. We believe that decisions about patient management should be based on enlightened clinical judgment rather than on preconceived notions about this population. In the quest for optimal health care delivery, the special needs of these patients should be considered when cardiac catheterization and possible cardiac surgery are contemplated. Although we have presented an approach to a patient with cardiac disease requiring cardiac surgery, we believe that this approach can be utilized for any retarded patient requiring acute medical care. Currently, because there has not been much training in this area, many physicians and nurses lack first-hand experience in caring for the mentally retarded. This inexperience may lead to

  13. Determination of the volatile fraction of phosphorus flame retardants in cushioning foam of upholstered furniture: towards respiratory exposure assessment.

    Science.gov (United States)

    Ghislain, Mylène; Beigbeder, Joana; Dumazert, Loïc; Lopez-Cuesta, José-Marie; Lounis, Mohammed; Leconte, Stéphane; Desauziers, Valérie

    2016-10-01

    The purpose of this paper was to highlight potential exposure in indoor air to phosphorus flame retardants (PFRs) due to their use in upholstered furniture. For that, an analytical method of PFRs by headspace coupled to solid-phase micro-extraction (HS-SPME) was developed on cushioning foams in order to determine the PFRs' volatile fraction in the material. Tests on model foams proved the feasibility of the method. The average repeatability (RSD) is 6.3 % and the limits of detection range from 0.33 to 1.29 μg g(-1) of foam, depending on the PFRs. Results showed that some PFRs can actually be emitted in air, leading to a potential risk of exposure by inhalation. The volatile fraction can be high (up to 98 % of the total PFRs amount) and depends on the physicochemical properties of flame retardants, on the textural characteristics of the materials and on the temperature. The methodology developed for cushioning foams could be further applied to other types of materials and can be used to rate them according to their potential releases of phosphorus flame retardants.

  14. Flammability of Cellulose-Based Fibers and the Effect of Structure of Phosphorus Compounds on Their Flame Retardancy

    Directory of Open Access Journals (Sweden)

    Khalifah A. Salmeia

    2016-08-01

    Full Text Available Cellulose fibers are promoted for use in various textile applications due their sustainable nature. Cellulose-based fibers vary considerably in their mechanical and flammability properties depending on their chemical composition. The chemical composition of a cellulose-based fiber is further dependent on their source (i.e., seed, leaf, cane, fruit, wood, bast, and grass. Being organic in nature, cellulose fibers, and their products thereof, pose considerable fire risk. In this work we have compared the flammability properties of cellulose fibers obtained from two different sources (i.e., cotton and peat. Compared to cotton cellulose textiles, peat-based cellulose textiles burn longer with a prominent afterglow which can be attributed to the presence of lignin in its structure. A series of phosphoramidates were synthesized and applied on both cellulose textiles. From thermogravimetric and pyrolysis combustion flow analysis of the treated cellulose, we were able to relate the flame retardant efficacy of the synthesized phosphorus compounds to their chemical structure. The phosphoramidates with methyl phosphoester groups exhibited higher condensed phase flame retardant effects on both types of cellulose textiles investigated in this study. In addition, the bis-phosphoramidates exhibited higher flame retardant efficacy compared to the mono-phosphoramidates.

  15. STRUCTURE OF BODY DEFORMATIES AMONG PERSONS WITH MENTAL RETARDATION

    Directory of Open Access Journals (Sweden)

    Blagoja GESHOSKI

    2010-04-01

    Full Text Available The purpose of this research was to assess body structure deformities among people with mental retardation.Knowing the structure of people with mental retardation’s physical deformities is the starting basis of a quality program for preventive and corrective work. Also, it is a starting point in the process of special education and rehabilitation in regards to their removal and mitigation.The structure of the physical deformities among persons with mental retardation were analyzed in terms of age and degree of mental retardation in relation to everyday life activities.The inquiry covered 170 respondents with mental retardation in both sexes. All respondents were placed in an institution for treatment of persons with severe and profound mental retardation (Special Institute Deep River. On the basis of two criteria, participants are divided into groups. The first criterion forestablishing a group of level of mental retardation: Group I - severe mental retardation (TMR and Group II - profound mental retardation (DMR. A second criterion for establishing the age group of respondents: Group I - age 18 years; Group II- Age 19 - 30 years and Group III - over 31 years. The structure of the physical deformities was analyzed in terms of age and degree of mental retardation in relation to activities in everyday life.For the purposes of the planned research , an integral protocol is established for the evaluation of physical deformities among persons with disabilities, including: an application form for general information about the respondents, a questionnaire to assess somatic status, and a clinical sheet and test activities in everyday life (Test ASZH, Rusk, 1971. All data obtained by the research are expressed quantitatively and treated with the following statistical methods and procedures: number of repetitions, frequency and percentages, measure of central tendency, the arithmetic mean and standard deviation, χ2 and Fisher Exact - test

  16. Prevalence of mental retardation among children in RS Pura town of Jammu and Kashmir

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Raina

    2012-01-01

    Full Text Available Objective: To determine the Prevalence of mental retardation in children 3 to 10 years of age. Materials and Methods: The study was conducted in the framework of a population based, single centre, cross-sectional study at R.S.Pura town, 22 kms south- west of Jammu city. Results: A total of 61 (0.79 percent of the 7,707 children surveyed had positive screening results on the Ten Questions instrument. 56 (0.72percent children were diagnosed as suffering from mental retardation. Serious mental retardation was diagnosed in 48 children and mild mental retardation was diagnosed in 8 children. The combined prevalence estimates of mild and serious mental retardation were 7.2/1000. No notable sex differences were observed for either serious or mild retardation. Interpretation: The prevalence rates of mental retardation among children less than 19 years of age in R. S. town compares favorably with studies from developed world.

  17. Modeling and prediction of retardance in citric acid coated ferrofluid using artificial neural network

    Science.gov (United States)

    Lin, Jing-Fung; Sheu, Jer-Jia

    2016-06-01

    Citric acid coated (citrate-stabilized) magnetite (Fe3O4) magnetic nanoparticles have been conducted and applied in the biomedical fields. Using Taguchi-based measured retardances as the training data, an artificial neural network (ANN) model was developed for the prediction of retardance in citric acid (CA) coated ferrofluid (FF). According to the ANN simulation results in the training stage, the correlation coefficient between predicted retardances and measured retardances was found to be as high as 0.9999998. Based on the well-trained ANN model, the predicted retardance at excellent program from Taguchi method showed less error of 2.17% compared with a multiple regression (MR) analysis of statistical significance. Meanwhile, the parameter analysis at excellent program by the ANN model had the guiding significance to find out a possible program for the maximum retardance. It was concluded that the proposed ANN model had high ability for the prediction of retardance in CA coated FF.

  18. Dynamics Models of Interacting Torques of Hydrodynamic Retarder Braking Process

    Directory of Open Access Journals (Sweden)

    Wenhao Shen

    2013-01-01

    Full Text Available Hydrodynamic retarder is a kind of assist braking device, which can transfer the vehicle kinetic energy into the heat energy of working medium. There are complicated three-dimensional viscous incompressible turbulent flows in hydrodynamic retarder, so that it is difficult to represent the parameters changing phenomenon and investigate the interactional law. In order to develop a kind of reliable theoretical model for internal flow field, in this study, the dynamics models of interacting torques between impellers and working fluid were constructed based on braking energy transfer principle by using Euler theory to describe the flow state in view of time scale. The model can truly represent the dynamic braking process.

  19. Mental retardation after prenatal exposure. Re-analysis indicated

    Energy Technology Data Exchange (ETDEWEB)

    Paile, W. [Finnish Centre for Radiation and Nuclear Safety (STUK), Helsinki (Finland). Radiation and Nuclear Safety Authority

    2000-05-01

    The current risk assessment for severe mental retardation after prenatal exposure to the A-bomb radiation is based on 21 cases exposed to more than 0.005 Gy, of which 17 were exposed in the most sensitive period 8-15 weeks p.c. The latest analysis, applying the best fitting model, indicates a threshold with a lower 95% bound of 0.06-0.31 Gy, depending on whether 2 cases with Down's syndrome are included or not. The authors have interpreted this as suggesting a threshold in the low-dose region. In the dose group 0.10-0.49 Gy, except one case with Down's syndrome there is only one other case, exposed 8 weeks p.c. to 0.14 Gy. However, in a RERF report (TR 13-91) concerning brain abnormalities detected by MRI in retarded persons, the same case is described. According to this report he was actually exposed to 0.86 Gy. The distance was 1060 m, and his mother exhibited severe epilation. These details indicate that the higher dose is correct and the lower dose is erroneous. In a small material the misclassification of one case has a deep influence on the result of the data analysis. Reclassification of this case will lead to a considerable change in the estimated threshold, notably in the 95% lower bound of the threshold. There will be no indication of severe retardation after less than 0.5 Gy even in the most sensitive period. This does not preclude a milder effect on intelligence from lower doses. The fraction of severe retardation after exposure to 1 Sv in the period 8-15 weeks p.c. has been estimated at 40%. The effect on intelligence score has been estimated at 30 IQ units per Sv in the same period. These estimates have been combined in ICRP 60 to create a model, based on a presumed normal distribution of IQ scores, according to which the final outcome for an individual is determined by his expected IQ without exposure. Thus the dose required to make an otherwise normal individual retarded would be high, while a much lower dose would be enough to bring an

  20. Quantum Computation Based on Retarded and Advanced Propagation

    CERN Document Server

    Castagnoli, G C

    1997-01-01

    Computation is currently seen as a forward propagator that evolves (retards) a completely defined initial vector into a corresponding final vector. Initial and final vectors map the (logical) input and output of a reversible Boolean network respectively, whereas forward propagation maps a one-way propagation of logical implication, from input to output. Conversely, hard NP-complete problems are characterized by a two-way propagation of logical implication from input to output and vice versa, given that both are partly defined from the beginning. Logical implication can be propagated forward and backward in a computation by constructing the gate array corresponding to the entire reversible Boolean network and constraining output bits as well as input bits. The possibility of modeling the physical process undergone by such a network by using a retarded and advanced in time propagation scheme is investigated.

  1. Carotenemia in mentally retarded children I. Incidence and etiology

    Science.gov (United States)

    Patel, H.; Dunn, H. G.; Tischler, B.; McBurney, A. Karaa

    1973-01-01

    The incidence and etiology of carotenemia in mentally retarded children were examined. Fasting serum carotenoid and vitamin A levels were measured in 77 profoundly mentally retarded children aged 3 to 19 years who were receiving a standard diet containing 2000 IU of carotene (expressed in terms of vitamin A activity) and supplemented by 2000 IU of vitamin A daily. Seventeen of the 77 patients had serum carotenoid levels of more than 300 μg./ml. The particulate size of food had a significant inverse relationship to serum carotenoid levels and was an important factor in determining carotenemia. The serum vitamin A level was also higher in children on homogenized diet than in those on pureed feeds, while the lowest level was noted among patients on a chopped diet. Besides particulate size of food, other factors may also be operative in determining carotenemia. PMID:4707231

  2. A STUDY ON CNV OF PATIENTS WITH MENTAL RETARDATION

    Institute of Scientific and Technical Information of China (English)

    CHEN Xingshi

    2002-01-01

    Objective: To investigate the variations of contingent negative variation (CNV) of petients with mental retardation. Methods: The CNV was recorded in 16 children with mental retardation (MR) and 14 healthly age-matched controls. And CNV retest was carried out in 11 children with MR after one yeat treatment of Piracetam. Results: Compared with the normal control, the CNV of MR group showed prolonged postimperative negative variation (PINV) duration (P<0.01) and total A-C duration (P < 0.01), decreased amplitude B (P<0.01 ), and reduced preimperative A-S2 area (P<0.01). A comparison of the CNV of MR group was made between before and after one year treatment of Piracetam and no significant difference was found. Conclusions:The significant CNV variations were found in children with MR and these abnormal changes presisted throughout the Piracetam treatment.

  3. Environmental Impact of Flame Retardants (Persistence and Biodegradability

    Directory of Open Access Journals (Sweden)

    Asher Brenner

    2009-02-01

    Full Text Available Flame-retardants (FR are a group of anthropogenic environmental contaminants used at relatively high concentrations in many applications. Currently, the largest market group of FRs is the brominated flame retardants (BFRs. Many of the BFRs are considered toxic, persistent and bioaccumulative. Bioremediation of contaminated water, soil and sediments is a possible solution for the problem. However, the main problem with this approach is the lack of knowledge concerning appropriate microorganisms, biochemical pathways and operational conditions facilitating degradation of these chemicals at an acceptable rate. This paper reviews and discusses current knowledge and recent developments related to the environmental fate and impact of FRs in natural systems and in engineered treatment processes.

  4. Fetishistic transvestism in a patient with mental retardation and psychosis

    Directory of Open Access Journals (Sweden)

    Rajmohan Velayudhan

    2014-01-01

    Full Text Available Fetishistic transvestism is a disorder of sexual preference associated with fantasies and sexual urges to dress in opposite gender clothing as a means of arousal and as an adjunct to masturbation and coitus. The disorder has been reported in people with learning disabilities. The disorder has been reported in a young male with dull normal intelligence. Transvestism though has been described in schizophrenia and psychosis and fetishism has been described in the course of simple schizophrenia, there are no reports of fetishistic transvestism in a patient with mental retardation and psychosis. A case of fetishistic transvestism in a patient with mental retardation and psychosis with treatment and relevant review of literature is reported.

  5. Health-promoting physical activity of adults with mental retardation.

    Science.gov (United States)

    Stanish, Heidi I; Temple, Viviene A; Frey, Georgia C

    2006-01-01

    This literature review describes the physical activity behavior of adults with mental retardation consistent with the U.S. Surgeon General's recommendation of 30 minutes of moderate intensity physical activity on 5 or more days per week. The proportion of participants achieving this criterion ranges from 17.5 to 33%. These data are likely to be generous estimates of activity as individuals included in physical activity studies to date have been relatively young and healthy volunteers with mild to moderate limitations. Major sources of physical activity were walking and cycling for transport, chores and work, dancing, and Special Olympics. There is a pressing need to conduct studies using appropriately powered representative samples and to validate measures that assess physical activity less directly; including methodologies in which proxy respondents are used. Accurate information about existing patterns of behavior will enhance the development of effective strategies to promote physical activity among persons with mental retardation.

  6. Improved fire retardancy of thermoset composites modified with carbon nanofibers

    Directory of Open Access Journals (Sweden)

    Zhongfu Zhao and Jan Gou

    2009-01-01

    Full Text Available Multifunctional thermoset composites were made from polyester resin, glass fiber mats and carbon nanofiber sheets (CNS. Their flaming behavior was investigated with cone calorimeter under well-controlled combustion conditions. The heat release rate was lowered by pre-planting carbon nanofiber sheets on the sample surface with the total fiber content of only 0.38 wt.%. Electron microscopy showed that carbon nanofiber sheet was partly burned and charred materials were formed on the combusting surface. Both the nanofibers and charred materials acted as an excellent insulator and/or mass transport barrier, improving the fire retardancy of the composite. This behavior agrees well with the general mechanism of fire retardancy in various nanoparticle-thermoplastic composites.

  7. Recurrent cholecystitis in an elderly mentally retarded patient with pica.

    Science.gov (United States)

    Miyakawa, Koichi; Ito, Masanobu; Hatta, Kotaro; Eto, Ko; Arai, Heii

    2011-12-01

    The case of a 64-year-old patient with pica and severe mental retardation who was admitted to our hospital for treatment of recurrent cholecystitis is reported. Abdominal ultrasound showed sludge in the gallbladder, but no stones. Abdominal CT revealed a foreign body in the duodenum resembling a suction cup of the type commonly used in kitchens and bathrooms. The object could not be removed because it was deeply embedded in the hypertrophic intestinal mucosa. A nasogastric tube was inserted for feeding, since the object impeded the passage of solid foods. The patient's fever and abdominal pain subsequently resolved, and laboratory data improved. The indwelling feeding tube prevented recurrence of cholecystitis. Since pica is common not only in patients with mental retardation but also in dementia patients, the present case may also relate to the treatment of acute abdominal conditions in dementia patients.

  8. Non syndromic gingival fibromatosis in a mild mental retardation child

    Directory of Open Access Journals (Sweden)

    Mahesh K Duddu

    2012-01-01

    Full Text Available Gingival fibromatosis is a benign oral condition characterized by enlargement of gingival tissues. It usually develops as an isolated disorder but can be one of the features of a syndrome. This case report is of a 5-year-old male with severe gingival hyperplasia and mild mental retardation which was complicated by open bite, abnormal occlusion, open lip posture, and disabilities associated with mastication and speech. Full mouth gingivectomy in single sitting under general anesthesia was done with electrocautery.

  9. Work function measurements by the field emission retarding potential method.

    Science.gov (United States)

    Strayer, R. W.; Mackie, W.; Swanson, L. W.

    1973-01-01

    Description of the theoretical foundation of the field electron retarding potential method, and review of its experimental application to the measurement of single crystal face work functions. The results obtained from several substrates are discussed. An interesting and useful fallout from the experimental approach described is the ability to accurately measure the elastic and inelastic reflection coefficient for impinging electrons to near zero-volt energy.

  10. A NEW POLYMERIC FLAME RETARDANT ADDITIVE FOR NYLON

    Institute of Scientific and Technical Information of China (English)

    M. SRINIVASAN; R. VASANTHAKUMARI; P. T. UTHIAH

    1993-01-01

    The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15 - 20% PPS into nylon-6 has provided UL V- 0 rating for the system and there is enhancement in tensile and flexural properties. The results obtained on the thermal, crystallization and flow characteristics of the nylon-PPS system uptoa loading of 40% PPS are also discussed.

  11. Psychopathology in Children and Adolescents with ASD without Mental Retardation

    Science.gov (United States)

    Caamaño, Marta; Boada, Leticia; Merchán-Naranjo, Jessica; Moreno, Carmen; Llorente, Cloe; Moreno, Dolores; Arango, Celso; Parellada, Mara

    2013-01-01

    This study analyzes subclinical psychopathology in children and adolescents with autism spectrum disorders (ASD) without mental retardation with no comorbid disorder, assessed by an extensive general psychopathology interview. The K-SADS-PL was administered to a group of 25 patients with ASD (mean age = 12.80 ± 2.86 years) and 25 healthy controls…

  12. Intumescent Biobased-Polylactide Films to Flame Retard Nonwovens

    OpenAIRE

    Christelle Reti; Mathilde Casetta, Ph.D.; Sophie Duquesne, Ph.D.; René Delobel; Serge Bourbigot; Jérémie Soulestin

    2009-01-01

    The work focuses on the development of a newprocess to flame retard nonwovens, using films basedon renewable resources. Films consist in intumescentformulations of polylactic acid (PLA), ammoniumpolyphosphate (APP) blended with lignin or starchand are coated on hemp or wool nonwovens. Theobjective of this study was to investigate the fireretardant and mechanical properties of textilesprotected by FR PLA films for potential use inbuilding applications. Horizontal and vertical flamespread tests...

  13. Skeletal demineralization and growth retardation in inflammatory bowel disease

    Energy Technology Data Exchange (ETDEWEB)

    Genant, H.K.; Mall, J.C.; Wagonfeld, J.B.; Vander Horst, J.; Lanzl, L.H.

    1976-01-01

    Skeletal growth and mineralization in 54 adolescent and adult patients with inflammatory bowel disease have been analyzed comprehensively. Quantitative and qualitative radiologic techniques consisted of conventional roentgenography, photon absorptiometry, and radiographic morphometry. The data are correlated with the type, duration, and severity of disease, and with several modes of therapy. The results indicate that osteopenia and retardation of growth are common in patients with inflammatory bowel disease, particularly in adolescents, in whom the effects of corticosteroids on the skeleton are most deleterious.

  14. Psychopathology in Children and Adolescents with ASD without Mental Retardation

    Science.gov (United States)

    Caamaño, Marta; Boada, Leticia; Merchán-Naranjo, Jessica; Moreno, Carmen; Llorente, Cloe; Moreno, Dolores; Arango, Celso; Parellada, Mara

    2013-01-01

    This study analyzes subclinical psychopathology in children and adolescents with autism spectrum disorders (ASD) without mental retardation with no comorbid disorder, assessed by an extensive general psychopathology interview. The K-SADS-PL was administered to a group of 25 patients with ASD (mean age = 12.80 ± 2.86 years) and 25 healthy controls…

  15. Demonstration of scattering suppression in retardation-based plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Nielsen, M.G.; Pors, A.; Nielsen, Rasmus Bundgaard;

    2010-01-01

    Modifications in scattering strength of and local field enhancement by retardation-based plasmonic nanoantennas when being transformed from straight nanorods to split-ring resonators are investigated experimentally. Scattering properties are characterized with linear reflection and extinction...... is decreased, a feature that is attributed to the decrease in the nanoantenna electric-dipole response when bending the nanorods. The experimental observations are corroborated with numerical simulations using the finite-element method....

  16. Hyperbranched Polyurethane Acrylate Applied to UV Curable Flame Retardant Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ UV curable hyperbranched prepolymers based on amine-ester, ester-amide and ether-amide started with AB2-type monomers have been prepared by the authors[1~3]. A se-ries of work on allyl ether maleate hyperbranched polyesters for UV curing coatings by Hult and his colleagues has been reported[4]. However, the UV cured films from those materials are all flammable when attached to fire without addition of flame retardants.

  17. Advanced-Retarded Differential Equations in Quantum Photonic Systems

    Science.gov (United States)

    Alvarez-Rodriguez, Unai; Perez-Leija, Armando; Egusquiza, Iñigo L.; Gräfe, Markus; Sanz, Mikel; Lamata, Lucas; Szameit, Alexander; Solano, Enrique

    2017-01-01

    We propose the realization of photonic circuits whose dynamics is governed by advanced-retarded differential equations. Beyond their mathematical interest, these photonic configurations enable the implementation of quantum feedback and feedforward without requiring any intermediate measurement. We show how this protocol can be applied to implement interesting delay effects in the quantum regime, as well as in the classical limit. Our results elucidate the potential of the protocol as a promising route towards integrated quantum control systems on a chip. PMID:28230090

  18. Growth retardation in children with chronic renal disease

    Directory of Open Access Journals (Sweden)

    Peco-Antić Amira

    2014-01-01

    Full Text Available Despite recent advances in the management of children with chronic renal disease (CRD, growth retardation remains its most visible comorbid condition. Growth retardation has adverse impact on morbidity and mortality rates, quality of life and education, and in adult patients on job family life, and independent leaving accomodation. Pathophysiology of impaired growth in CRD is complex and still not fully understood. The following complications are: anorexia, malnutrition, inflammation, decreased residual renal function, dialysis frequency and adequacy, renal anemia, metabolic acidosis, fluid/electrolyte imbalance, renal osteodistrophy, growth hormone (GH and insulin-like growth factor -1 (IGF-1 resistance. Malnutrition is most frequent and most important factor contributing to the degree of growth retardation in infancy. The degree of renal dysfunction is the major determinant of variability in growth from third year of age until puberty onset, while in puberty hypergonadotropic hypogonadism has negative effect. The main factors that influence growth after renal transplantation are the age of the recipient and glucocorticoid drugs dosage with negative effect and allograft function with positive effect. In order to improve growth in children with CRD it is necessary to include: diet with optimal caloric intake, correction of fluid/ electrolyte imbalance, correction of acidosis, renal osteodistrophy and anemia. If growth velocity is insufficient to normalize growth, it is necessary to start recombinant human GH (rhGH therapy at 0.05 mg/kg per day (0.35 mg/kg per week or 28 IU/m2 per week administered by subcutaneous injection.

  19. Flame retardant exposures in California early childhood education environments.

    Science.gov (United States)

    Bradman, Asa; Castorina, Rosemary; Gaspar, Fraser; Nishioka, Marcia; Colón, Maribel; Weathers, Walter; Egeghy, Peter P; Maddalena, Randy; Williams, Jeffery; Jenkins, Peggy L; McKone, Thomas E

    2014-12-01

    Infants and young children spend as much as 50h per week in child care and preschool. Although approximately 13 million children, or 65% of all U.S. children, spend some time each day in early childhood education (ECE) facilities, little information is available about environmental exposures in these environments. We measured flame retardants in air and dust collected from 40 California ECE facilities between May 2010 and May 2011. Low levels of six polybrominated diphenyl ether (PBDE) congeners and four non-PBDE flame retardants were present in air, including two constituents of Firemaster 550 and two tris phosphate compounds [tris (2-chloroethyl) phosphate (TCEP) and tris (1,3-dichloroisopropyl) phosphate (TDCIPP)]. Tris phosphate, Firemaster 550 and PBDE compounds were detected in 100% of the dust samples. BDE47, BDE99, and BDE209 comprised the majority of the PBDE mass measured in dust. The median concentrations of TCEP (319 ng g(-1)) and TDCIPP (2265 ng g(-1)) were similar to or higher than any PBDE congener. Levels of TCEP and TDCIPP in dust were significantly higher in facilities with napping equipment made out of foam (Mann-Whitney p-valuesflame retardant chemicals.

  20. Flame retardants: Dust - And not food - Might be the risk.

    Science.gov (United States)

    de Boer, J; Ballesteros-Gómez, A; Leslie, H A; Brandsma, S H; Leonards, P E G

    2016-05-01

    Flame retardants (FRs) are used to delay ignition of materials such as furniture and electric and electronic instruments. Many FRs are persistent and end up in the environment. Environmental studies on flame retardants (FRs) took off in the late 1990s. Polybrominated diphenylethers (PBDEs) appeared to be bioaccumulative and were found in many organisms all over the world. When PBDEs were banned or their production voluntarily terminated, alternatives appeared on the market that often had similar properties or were of more concern due to their toxicity such as halogenated phosphorus-based FRs. Here we show that in spite of the ban on PBDEs more brominated FRs are being produced, an increasing number of other FRs is being applied and FR levels in our homes are much higher than in the outdoor environment. While nowadays we live in better isolated houses and sit in front of the computer or television, on flame retarded upholstery, we are at risk due to the toxic effects of a suite of FRs. The high exposure to these substances indoors calls for better risk assessments that include mixture effects.

  1. Synergistic effects of sepiolite on intumescent flame retardant polypropylene

    Directory of Open Access Journals (Sweden)

    2010-12-01

    Full Text Available In this paper, the effects of sepiolite as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene (PP/IFR were studied using the limiting oxygen index (LOI, the UL-94 test, thermogravimetric analysis (TGA, laser Raman spectroscopy (LRS, cone calorimeter test (CCT and scanning electron microscopy (SEM, and the IFR system mainly consisted of the ammonium polyphosphate modified with γ-aminopropyltriethoxysilane coupling agent, melamine and dipentaerythritol. The results from the LOI and UL 94 tests show that sepiolite added to the PP/IFR system has a synergistic flame retardant effects with the IFR system. The TGA results reveal that sepiolite enhances the thermal stability of the PP/IFR composite and increases the char residue formation. The cone calorimeter results indicate that the heat release rate, mass loss rate, total heat release and average specific extinction area of the PP/IFR/sepiolite composite decrease in comparison with the PP/IFR composite. The LRS measurements provide useful information on the carbonaceous microstructures. The morphological structures observed by SEM have demonstrated that sepiolite promote the formation of the reinforced and homogeneous char barrier on the surface of the composites. Simultaneously, the Young’s modulus and flexural modulus of the PP/IFR composites are also much better improved with the increase of sepiolite added.

  2. Partial beta-amylolysis retards starch retrogradation in rice products.

    Science.gov (United States)

    Yao, Yuan; Zhang, Jingmin; Ding, Xiaolin

    2003-07-02

    Starch retrogradation is the main cause of quality deterioration of starch-containing foods during storage. The current work investigated the effect of partial beta-amylolysis on the retrogradation of rice starch and the potential of beta-amylase in preparing rice products with extended shelf life. Isolated amylopectin, whole rice starch, and rice flour from a regular rice cultivar were partially hydrolyzed by either reagent-grade or food-grade beta-amylase. The degree of beta-amylolysis was expressed as average external chain length () for isolated amylopectin or the degree of hydrolysis (%) for other starch systems. Pulsed nuclear magnetic resonance was used to monitor starch retrogradation during storage at 4 degrees C. The results indicated that partial beta-amylolysis using reagent-grade beta-amylase retarded amylopectin retrogradation by shortening the of amylopectin. When was below DP 11.6, the amylopectin retrogradation was essentially inhibited. Partial beta-amylolysis had a similar effect on the amylopectin retrogradation in the whole starch system. The maltose produced in beta-amylolysis might slightly attenuate the retrogradation-retarding effect of partial beta-amylolysis. The effect of food-grade beta-amylase on starch retrogradation was also evident, although less effective than that of reagent-grade beta-amylase. The retrogradation-retarding effect of food-grade beta-amylase was also demonstrated in rice flour system, indicating a potential method for controlling the starch retrogradation of rice products.

  3. Approach to Mental Retardation and Global Developmental Delay

    Directory of Open Access Journals (Sweden)

    Mahmoud Reza ASHRAFI

    2011-04-01

    Full Text Available ObjectiveMental Retardation (MR or Intellectual Disability is one of three chronic and disabling neurological disorders of children and adolescents. Its prevalence is estimated 1-3% of the population. MR is defined as significant sub-average intellectual functioning and adaptive behavior that become detectable before the age of 18. MR may come into view before 5 years as delay in at least two developmental domains which is called Global Developmental Delay (GDD.The causes of mental retardation can be considered under the titles of prenatal, perinatal and postnatal factors. Prenatal causes account for approximately 60 -80 % of the etiological factors. All patients with GDD / MR should undergo a stepwise diagnostic approach, because a specific diagnosis leads to opportunity for treatment, future planning and genetic counseling. History, physical examination and neurodevelopmental examinations are the most important parts of the approach. Recent advances in cytogenetic investigations and neuroimaging studies have led to recognition of new disorders and improvement of the diagnostic yield.Keywords: Mental retardation ; global developmental delay; diagnostic yield.

  4. Epilepsy, speech delay, and mental retardation in facioscapulohumeral muscular dystrophy.

    Science.gov (United States)

    Grosso, Salvatore; Mostardini, Rosa; Di Bartolo, Rosanna Maria; Balestri, Paolo; Verrotti, Alberto

    2011-09-01

    Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies which is related to the deletion of tandem repeats on chromosome 4q35. Extramuscular features such as hearing loss, retinopathy, mental retardation, and epilepsy, may be observed in patients carrying large 4q35 deletions resulting in fragment sizes less than 12 kilobases (kb) (normal >35 kb). We report on a family affected by FSHD carrying a small 4q35 deletion and residual fragments length of 17 kb, presenting with epilepsy (three patients), speech delay (two), and mental retardation (one). In all patients semeiology of seizures and interictal EEG anomalies were congruent with a localization-related epilepsy possibly involving the temporal lobe. In conclusion, we provide further evidences that extramuscular findings such as epilepsy, speech delay, and mental retardation may occur in those patients carrying smaller 4q35 deletions, suggesting that a close correlation between 4q35 fragment size and clinical severity in FSHD is therefore not constant. Moreover, a review of the literature and our observations seem to suggest that focal epilepsies, likely related to the temporal lobe in the present family, represent the main type of epilepsy occurring in children with FSHD. Copyright © 2011 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

  5. X chromosome inactivation and X-linked mental retardation

    Energy Technology Data Exchange (ETDEWEB)

    Willard, H.F. [Case Western Reserve Univ. School of Medicine, Cleveland, OH (United States)]|[Univ. Hospitals of Cleveland, OH (United States)

    1996-07-12

    The expression of X-linked genes in females heterozygous for X-linked defects can be modulated by epigenetic control mechanisms that constitute the X chromosome inactivation pathway. At least four different effects have been found to influence, in females, the phenotypic expression of genes responsible for X-linked mental retardation (XLMR). First, non-random X inactivation, due either to stochastic or genetic factors, can result in tissues in which one cell type (for example, that in which the X chromosome carrying a mutant XLMR gene is active) dominates, instead of the normal mosaic cell population expected as a result of random X inactivation. Second, skewed inactivation of the normal X in individuals carrying a deletion of part of the X chromosome has been documented in a number of mentally retarded females. Third, functional disomy of X-linked genes that are expressed inappropriately due to the absence of X inactivation has been found in mentally retarded females with structurally abnormal X chromosomes that do not contain the X inactivation center. And fourth, dose-dependent overexpression of X-linked genes that normally {open_quotes}escape{close_quotes} X inactivation may account for the mental and developmental delay associated with increasing numbers of otherwise inactive X chromosomes in individuals with X chromosome aneuploidy. 53 refs., 1 fig.

  6. Nabumetone induces less gastrointestinal mucosal changes than diclofenac retard.

    Science.gov (United States)

    Becvár, R; Urbanová, Z; Vlasáková, V; Vítová, J; Rybár, I; Maldyk, H; Filipowicz-Sosnowska, A; Bernacka, K; Mackiewicz, S; Gömör, B; Rojkovich, B; Siro, B; Bereczki, J; Toth, K; Sukenik, S; Green, L; Ehrenfeld, M; Pavelka, K

    1999-01-01

    The aim of the study was to compare the efficacy and the effects on the mucosa of the gastrointestinal tract (GIT) of nabumetone and diclofenac retard in patients with osteoarthritis (OA). An open, multicentre, randomised, comparative, endoscopy-blind parallel group study included 201 patients with nabumetone and 193 patients with diclofenac retard suffering from moderate to severe OA of the knee or hip joint. Twelve clinical efficacy variables were assessed and a portion of the population underwent gastroduodenoscopy. All patients exhibited significant improvement in pain severity and pain relief (p nabumetone and 19% on diclofenac experienced GIT side-effects. Sixty-nine patients with nabumetone and 61 with diclofenac underwent gastroduodenoscopy. The differences in the mucosal grade for the oesophagus, stomach and duodenum at baseline were not significant. In the oesophagus there were significantly less changes after treatment with nabumetone (p = 0.007) than with diclofenac; there were similar findings in the stomach (p nabumetone and diclofenac retard have similar efficacy in the treatment of OA, but nabumetone has significantly fewer GIT side-effects.

  7. Mental Retardation: General Information. Fact Sheet Number 8 = El Retraso Mental; Informacion General. Fact Sheet Number 16.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on mental retardation is offered in both English and Spanish. First it provides the federal definition of mental retardation and discusses components of the definition. Causes of mental retardation are briefly noted, and incidence figures are provided. Typical characteristics of people with mental retardation are mentioned.…

  8. Mental Retardation: General Information. Fact Sheet Number 8 = El Retraso Mental; Informacion General. Fact Sheet Number 16.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on mental retardation is offered in both English and Spanish. First it provides the federal definition of mental retardation and discusses components of the definition. Causes of mental retardation are briefly noted, and incidence figures are provided. Typical characteristics of people with mental retardation are mentioned.…

  9. Retardation of thermal and urea induced inactivation of alpha-chymotrypsin by modification with carbohydrate polymers.

    Science.gov (United States)

    Sundaram, P V; Venkatesh, R

    1998-08-01

    Modification of enzymes by means of covalent coupling using soluble polymers results in enzymes which retain high biological activity and display resistance to denaturants, high temperature and chaotropic agents. Alpha-chymotrypsin, which has a potential for use in industrial applications, was covalently modified by reductive alkylation using polymeric sucrose (OSP, molecular weight 70 and 400 kDa), dextran (73 and 250 kDa) and carboxymethyl cellulose (CMC, approximately 12 kDa). The derivatives retained around 50-80% activity depending on the polymer used and the extent of modification. At the same time, they displayed better thermotolerance than their native counterpart with 4-14 degrees C higher T50 values. During thermal inactivation, both the native and modified enzymes showed biphasic inactivation kinetics. Half-life of modified enzymes were 2-66-fold greater for the first phase and 5-250-fold greater than the native for the second phase of inactivation. The activation free energy of inactivation of alpha-chymotrypsin coupled to polymeric sucrose (400 kDa) was 112.85 kJ/mol for the first phase and 114.71 kJ/mol for the second phase, whereas in the case of the native enzyme, the value for the first phase was 101.55 kJ/mol and 103.42 kJ/mol for the second phase. The activation free energy of inactivation (deltaG*), as well as the activation enthalpy values (deltaH*) of all the modified enzymes were greater than those of the native enzyme, which is an indication of stabilization of the protein and a retardation of inactivation that is usually accompanied by unfolding under thermal and chemical stress. The stability of modified alpha-chymotrypsin is in the following order: OSP 400-C > OSP 70-C > CMC-C > Dextran 73-C = Dextran 250-C.

  10. Craniotubular dysplasia with severe postnatal growth retardation, mental retardation, ectodermal dysplasia, and loose skin: Lenz-Majewski-like syndrome.

    Science.gov (United States)

    Nishimura, G; Harigaya, A; Kuwashima, M; Kuwashima, S

    1997-07-11

    The heterogeneous group of craniotubular dysplasias is characterized by modeling errors of the craniofacial and tubular bones. Some conditions in this category cause not only skeletal abnormalities but also a variety of mesoectodermal dysplasias, as exemplified in Lenz-Majewski syndrome (MIM 151050), which comprises craniodiaphyseal dysplasia, failure to thrive, mental retardation, proximal symphalangism, enamel hypoplasia, and loose skin. We report on a boy with a hitherto unknown multisystem disorder, including skeletal changes that were regarded as a form of craniotubular dysplasia. The patient had a large head, exophthalmos, a broad nasal root, anteverted nostrils, large auricles, thick lips, micrognathia, severe postnatal growth retardation with emaciation, severe mental retardation, sparse hair growth, enamel hypoplasia, and thin, loose skin with hyperlaxity. Skeletal changes consisted of thickened calvaria, sclerosis of the skull base and facial bones, thick ribs, and metaphyseal undermodeling of the tubular bones. In addition, generalized osteopenia was evident. The present disorder overlaps phenotypically with Lenz-Majewski syndrome; nevertheless, the absence of diaphyseal hyperostosis and proximal symphalangism in the present patient was not consistent with Lenz-Majewski syndrome.

  11. Preparation and Flame-retardant Mechanism of Flame Retarded LGF/PA6 Composites%阻燃型LGF/PA6复合材料的制备及阻燃机理研究

    Institute of Scientific and Technical Information of China (English)

    左晓玲; 张凯舟; 邵会菊; 瞿进; 郝智; 郭建兵

    2013-01-01

    Long-glass-fiber reinforced polyamide 6 composites were flame retarded with an halogenic flame retardant (FR/LGF/PA6) system containing brominated epoxy resins (BER) synchronized with antimony trioxide (Sb2O3).The effects of BER and Sb2O3 on the flame retarding properties of the LGF/PA6 were studied by LOI,UL-94measurements,TGA,cone tests and FT-IR.The results demonstrated that the LOI value and UL-94 rating of FR/LGF/PA6 composites reached at 23.9% and FV-0,respectively,and exhibited much better mechanical properties for the sample containing 12 wt% BER synchronized with antimony trioxide Sb 2O 3.The cone and thermal gravimetric showed that the thermal stability of FR/LGF/PA6 composites was raised by brominated epoxy resins in synchronizing antimony trioxide,so that retard the decomposing rate of PA6 and played an important role in flame retardance.The problem of "candlewick"effect related to the glass fiber was successfully solved by the introduction of flame retarded system.FT-IR and cone showed that the residue char after heat treatment of LGF/PA6 and FR/LGF/PA6 was not the same completely,which indicated that the BER/Sb2O3 system had flame retarded effects not only in gaseous phase but also in condensed phase.%利用溴化环氧树脂(BER)协同三氧化二锑(Sb2O3)制备新型卤素阻燃长玻纤增强尼龙6复合材料(FR/LGF/PA6).通过极限氧指数(LOI)、垂直燃烧(UL94)、热重分析法(TGA)、锥形量热(cone)、红外光谱分析(FTIR)等方法研究了BER协同Sb2O3对长玻纤增强尼龙6复合材料阻燃性能影响.结果表明:在BER与Sb2O3的协效阻燃体系质量分数为12%时,可使FR/LGF/PA6复合材料的阻燃等级达到FV-0级,LOI为23.9%,且力学性能表现为最佳.锥形量热与热失重分析均表明:BER协同Sb2O3能提高FR/LGF/PA6复合材料的热稳定性,缓解PA6分解速率,从而起到良好的阻燃作用,成功地解决了玻纤增强材料燃烧时的“烛芯效应”问题.红外光谱和锥形

  12. Modeling and prediction of retardance in citric acid coated ferrofluid using artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jing-Fung, E-mail: jacklin@cc.feu.edu.tw [Department of Industrial Design, Far East University, Taiwan, ROC (China); Sheu, Jer-Jia [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Taiwan, ROC (China)

    2016-06-01

    Citric acid coated (citrate-stabilized) magnetite (Fe{sub 3}O{sub 4}) magnetic nanoparticles have been conducted and applied in the biomedical fields. Using Taguchi-based measured retardances as the training data, an artificial neural network (ANN) model was developed for the prediction of retardance in citric acid (CA) coated ferrofluid (FF). According to the ANN simulation results in the training stage, the correlation coefficient between predicted retardances and measured retardances was found to be as high as 0.9999998. Based on the well-trained ANN model, the predicted retardance at excellent program from Taguchi method showed less error of 2.17% compared with a multiple regression (MR) analysis of statistical significance. Meanwhile, the parameter analysis at excellent program by the ANN model had the guiding significance to find out a possible program for the maximum retardance. It was concluded that the proposed ANN model had high ability for the prediction of retardance in CA coated FF. - Highlights: • The feedforward ANN is applied for modeling of retardance in CA coated FFs. • ANN can predict the retardance at excellent program with acceptable error to MR. • The proposed ANN has high ability for the prediction of retardance.

  13. Thin-Film Composite Pressure Retarded Osmosis Membranes for Sustainable Power Generation from Salinity Gradients

    KAUST Repository

    Yip, Ngai Yin

    2011-05-15

    Pressure retarded osmosis has the potential to produce renewable energy from natural salinity gradients. This work presents the fabrication of thin-film composite membranes customized for high performance in pressure retarded osmosis. We also present the development of a theoretical model to predict the water flux in pressure retarded osmosis, from which we can predict the power density that can be achieved by a membrane. The model is the first to incorporate external concentration polarization, a performance limiting phenomenon that becomes significant for high-performance membranes. The fabricated membranes consist of a selective polyamide layer formed by interfacial polymerization on top of a polysulfone support layer made by phase separation. The highly porous support layer (structural parameter S = 349 μm), which minimizes internal concentration polarization, allows the transport properties of the active layer to be customized to enhance PRO performance. It is shown that a hand-cast membrane that balances permeability and selectivity (A = 5.81 L m-2 h-1 bar-1, B = 0.88 L m-2 h-1) is projected to achieve the highest potential peak power density of 10.0 W/m2 for a river water feed solution and seawater draw solution. The outstanding performance of this membrane is attributed to the high water permeability of the active layer, coupled with a moderate salt permeability and the ability of the support layer to suppress the undesirable accumulation of leaked salt in the porous support. Membranes with greater selectivity (i.e., lower salt permeability, B = 0.16 L m-2 h-1) suffered from a lower water permeability (A = 1.74 L m-2 h-1 bar-1) and would yield a lower peak power density of 6.1 W/m2, while membranes with a higher permeability and lower selectivity (A = 7.55 L m-2 h-1 bar-1, B = 5.45 L m-2 h-1) performed poorly due to severe reverse salt permeation, resulting in a similar projected peak power density of 6.1 W/m2. © 2011 American Chemical Society.

  14. Distribution of copper, silver and gold during thermal treatment with brominated flame retardants

    Energy Technology Data Exchange (ETDEWEB)

    Oleszek, Sylwia, E-mail: sylwia_oleszek@yahoo.com [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, 34 M. Sklodowska-Curie St., 41-819 Zabrze (Poland); Grabda, Mariusz, E-mail: mariusz@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, 34 M. Sklodowska-Curie St., 41-819 Zabrze (Poland); Shibata, Etsuro, E-mail: etsuro@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Nakamura, Takashi, E-mail: ntakashi@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan)

    2013-09-15

    Highlights: • Copper, silver and gold during thermal treatment with brominated flame retardants. • Distribution of copper, silver and gold during thermal processing. • Thermodynamic considerations of the bromination reactions. - Abstract: The growing consumption of electric and electronic equipment results in creating an increasing amount of electronic waste. The most economically and environmentally advantageous methods for the treatment and recycling of waste electric and electronic equipment (WEEE) are the thermal techniques such as direct combustion, co-combustion with plastic wastes, pyrolysis and gasification. Nowadays, this kind of waste is mainly thermally treated in incinerators (e.g. rotary kilns) to decompose the plastics present, and to concentrate metals in bottom ash. The concentrated metals (e.g. copper, precious metals) can be supplied as a secondary raw material to metal smelters, while the pyrolysis of plastics allows the recovery of fuel gases, volatilising agents and, eventually, energy. Indeed, WEEE, such as a printed circuit boards (PCBs) usually contains brominated flame retardants (BFRs). From these materials, hydrobromic acid (HBr) is formed as a product of their thermal decomposition. In the present work, the bromination was studied of copper, silver and gold by HBr, originating from BFRs, such as Tetrabromobisphenol A (TBBPA) and Tetrabromobisphenol A-Tetrabromobisophenol A diglycidyl ether (TTDE) polymer; possible volatilization of the bromides formed was monitored using a thermo-gravimetric analyzer (TGA) and a laboratory-scale furnace for treating samples of metals and BFRs under an inert atmosphere and at a wide range of temperatures. The results obtained indicate that up to about 50% of copper and silver can evolve from sample residues in the form of volatile CuBr and AgBr above 600 and 1000 °C, respectively. The reactions occur in the molten resin phase simultaneously with the decomposition of the brominated resin. Gold is

  15. Built-up Effect of Core Material for Microencapsulated Flame Retardant Containing Dimethyl Methyl Phosphate

    Institute of Scientific and Technical Information of China (English)

    LIN Miao; DONG Kai; YANG Yong

    2008-01-01

    The flame retardants containing organophosphorus compounds have extensively been used inthe flame retarding of polymer materials.Among others,dimethyl methyl phosphate (DMMP) was applied in flame retarding of polyurethane owmg to its so much merit.However,the water-soluble property of DMMP restricted its application in textile fabric.The flame retardtag systemcontainirm DMMP will be microencapsulated to form a novel flame retardant that could be used in textiles.We have studied the builtup effect of DMMP with some inorganic compounds to improve the afterflame and afterglow suppression in the flame retarding system.The experimeatal data indicated that inorganic compounds containing various non-metal elements P,N,B and metal ions Mg2+,Al3+,Ca2+,Zn2+,Cu2+,Mn4+ could be applied in flame retarding systems as additives to effectively suppress afterflame or afterglow.

  16. Synthesis of Antistatic Composite Based on Reaction Flame Retarding Unsaturated Polyester Resin

    Institute of Scientific and Technical Information of China (English)

    WANG Shui-ping; GONG Wen-hua; ZENG Jia

    2002-01-01

    The synthesis of reaction flame retarding unsaturated polyester resin and the flame retarding mechanism are investigated. By taking the synthesis flame retarding unsaturated polyester resin as a base material,glass fibers as reinforced material, under the condition of adding graphite or carbon black respectively, the composites were manufactured. The flame retarding and antistatic properties are also studied. In the experiment, bromidebearing flame retarding resin decomposed under a high temperature. Compound HBr was set out and retarded or stopped the flame. High concentration of HBr gas wall was formed between gas and solid phrases, which decreased flame. The results show that antistatic property of carbon black is higher than that of graphite. Adding a threshed value of 1% carbon black into composite, the antistatic property is at its highest value.

  17. Study of the Synergistic Effect of Nanoporous Nickel Phosphates on Novel Intumescent Flame Retardant Polypropylene Composites

    Directory of Open Access Journals (Sweden)

    Shibin Nie

    2015-01-01

    Full Text Available A char forming agent (CFA and silica-gel microencapsulated ammonium polyphosphate (Si-MCAPP were selected to form novel intumescent flame retardant system to prepare flame retardant polypropylene (PP composites, and then the influences of nanoporous nickel phosphates (NiP on the thermal and flame retardant properties of flame retardant PP composites were studied by the real time FTIR (RTFTIR spectra, limited oxygen index (LOI test, and the scanning electron microscopy. RTFTIR shows the addition of NiP can improve the thermal stability of flame retardant PP composites. LOI test shows LOI value is increased with the increase of the content of NiP, and the optimized concentration of NiP is 1.0%. Furthermore, smoke toxicity of the novel flame retardant PP composites was studied by mice experiment. The upper limit of the no death smoke concentration of the composite is 12.37 mg/L.

  18. Synthesis,Characterization and Flame-retardant Properties of Epoxy Resins and AACHH Composites

    Institute of Scientific and Technical Information of China (English)

    QIN Linqing; ZHANG Lianmeng; HUANG Zhixiong; HUANG Zhiliang; WANG Yanbing

    2009-01-01

    Flame retardant epoxy resins were prepared by a simple mixed method using am-monium aluminum carbonate hydroxy hydrate(AACHH)as a halogen-free flame retardant.The pre-pared samples were characterized by X-ray diffraction,thermogravimetric and differential scanning calorimetry,scanning electron microscope and limiting oxygen index(LOI)experiments.Effects of AACHH content on LOI of epoxy resins/AACHH composite and flame retardant mechanism were investigated and discussed.Results show that AACHH exhibites excellent flame-retardant properties in epoxy resin(EP).When the content of AACHH was 47.4%,the LOI of EP reached 32.2%.Moreover, the initial and terminal decomposition temperature of EP increased by 48 ℃and 40℃,respectively. The flame retarded mechanism of AACHH is due to the synergic flame retardant effects of diluting, cooling,decomposition resisting and obstructing.

  19. Inhalation a significant exposure route for chlorinated organophosphate flame retardants.

    Science.gov (United States)

    Schreder, Erika D; Uding, Nancy; La Guardia, Mark J

    2016-05-01

    Chlorinated organophosphate flame retardants (ClOPFRs) are widely used as additive flame retardants in consumer products including furniture, children's products, building materials, and textiles. Tests of indoor media in homes, offices, and other environments have shown these compounds are released from products and have become ubiquitous indoor pollutants. In house dust samples from Washington State, U.S.A., ClOPFRs were the flame retardants detected in the highest concentrations. Two ClOPFRs, tris(1,3-dichloro-2-propyl)phosphate (TDCPP or TDCIPP) and tris(2-chloroethyl)phosphate (TCEP), have been designated as carcinogens, and there is growing concern about the toxicity of the homologue tris(1-chloro-2-propyl)phosphate (TCPP or TCIPP). In response to concerns about exposure to these compounds, the European Union and a number of U.S. states have taken regulatory action to restrict their use in certain product categories. To better characterize exposure to ClOPFRs, inhalation exposure was assessed using active personal air samplers in Washington State with both respirable and inhalable particulate fractions collected to assess the likelihood particles penetrate deep into the lungs. Concentrations of ∑ClOPFRs (respirable and inhalable) ranged from 97.1 to 1190 ng m(-3) (mean 426 ng m(-3)), with TCPP detected at the highest concentrations. In general, higher levels were detected in the inhalable particulate fraction. Total intake of ClOPFRs via the inhalation exposure route was estimated to exceed intake via dust ingestion, indicating that inhalation is an important route that should be taken into consideration in assessments of these compounds.

  20. AN S- AND P-CONTAINING FLAME RETARDANT FOR POLYPROPYLENE

    Institute of Scientific and Technical Information of China (English)

    Hua-qiao Peng; De-yi Wang; Qian Zhou; Yu-zhong Wang

    2008-01-01

    A novel charring agent, bis(1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane) phenylphosphine sulfide (BCPPS), has been synthesized, and it is combined with ammonium polyphosphate (APP) and melamine phosphate (MP) to impart flame retardance and dripping resistance for polypropylene (PP). The fire performance of the treated PP is investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter, and the thermal stability and thermal oxidative stability of the composites are studied using thermogravimetric analysis (TG). It has been found that the treated PP with the optimal flame retardant formulation of APP:MP:BCPPS = 12:6:12 (weight ratio, formulation 10)gives an LOI of 31.3 and UL-94 V-0 rating. The results from cone calorimeter indicate that both the heat release rate (HRR)and the total heat evolved (THE) of IFR-PP (formulation 10) decrease significantly compared with those of neat PP. The TG result shows that the IFR-PP (formulation 10) has a high yield of residual char at high temperature. FTIR is used to investigate the residue of the treated PP that degrades at 400℃ for different time. The compact outer surface and the shaggy inner surface can be observed from the SEM graph of the residual chars after LOI test, which form a much better barrier for the transfer of heat and fuel during combustion and show good flame retardancy. Moreover, the treated PP and its residue are investigated by XPS analysis.

  1. Recycling of plastic waste: Screening for brominated flame retardants (BFRs).

    Science.gov (United States)

    Pivnenko, K; Granby, K; Eriksson, E; Astrup, T F

    2017-08-30

    Flame retardants are chemicals vital for reducing risks of fire and preventing human casualties and property losses. Due to the abundance, low cost and high performance of bromine, brominated flame retardants (BFRs) have had a significant share of the market for years. Physical stability on the other hand, has resulted in dispersion and accumulation of selected BFRs in the environment and receiving biota. A wide range of plastic products may contain BFRs. This affects the quality of waste plastics as secondary resource: material recycling may potentially reintroduce the BFRs into new plastic product cycles and lead to increased exposure levels, e.g. through use of plastic packaging materials. To provide quantitative and qualitative data on presence of BFRs in plastics, we analysed bromophenols (tetrabromobisphenol A (TBBPA), dibromophenols (2,4- and 2,6-DBP) and 2,4,6-tribromophenol (2,4,6-TBP)), hexabromocyclododecane stereoisomers (α-, β-, and γ-HBCD), as well as selected polybrominated diphenyl ethers (PBDEs) in samples of household waste plastics, virgin and recycled plastics. A considerable number of samples contained BFRs, with highest concentrations associated with acrylonitrile butadiene styrene (ABS, up to 26,000,000ngTBBPA/g) and polystyrene (PS, up to 330,000ng∑HBCD/g). Abundancy in low concentrations of some BFRs in plastic samples suggested either unintended addition in plastic products or degradation of higher molecular weight BFRs. The presence of currently restricted flame retardants (PBDEs and HBCD) identified in the plastic samples illustrates that circular material flows may be contaminated for extended periods. The screening clearly showed a need for improved documentation and monitoring of the presence of BFRs in plastic waste routed to recycling. Copyright © 2017. Published by Elsevier Ltd.

  2. Chromosomal abnormalities associated with mental retardation in female subjects

    Directory of Open Access Journals (Sweden)

    Dutta Samikshan

    2009-01-01

    Full Text Available Chromosomal abnormalities are thought to be the most common cause of mental retardation (MR. However, apart from a few selected types with typical aneuploidy, like Downs syndrome, Klinefelter syndrome, Turner syndrome, etc., the frequency of detectable chromosomal abnormalities in association with idiopathic MR is very low. In this study, we have investigated chromosomal abnormalities in female MR subjects (n = 150 by high-resolution GTG banding. Of them, 30 cases were diagnosed as Downs syndrome. Among the remaining (n = 120, chromosomal abnormalities/marked polymorphisms were detectable in only three MR cases (0.025.

  3. Fast switchable electro-optic radial polarization retarder

    CERN Document Server

    Lim, B C; Lai, W J; Hong, M H

    2008-01-01

    A fast, switchable electro-optic radial polarization retarder (EO-RPR) fabricated using the electro-optic ceramic PMN-PT is presented. This EO-RPR is useful for fast, switchable generation of pure cylindrical vector beam. When used together with a pair of half-wave plates, the EO-RPR can change circularly polarized light into any cylindrical vector beam of interest such as radially or azimuthally polarized light. Radially and azimuthally polarized light with purities greater than 95% are generated experimentally. The advantages of using EO-RPR include fast response times, low driving voltage and transparency in a wide spectral range (500 -7000 nm).

  4. [Schooling of patients exhibiting Autism Spectrum Disorders without mental retardation].

    Science.gov (United States)

    Grimm, D; Assouline, B; Piero, A

    2015-12-01

    Autism Spectrum Disorders belong to Pervasive Development Disorders. Although access to education is recommended by the French National High Authority for Health (HAS), the practice remains limited and the reasons for the low education rate of these children have still not been sufficiently explored in the literature. The main objective of this study was to analyze the links between Autism Spectrum Disorder without mental retardation, psychiatric comorbidity and education. The secondary objective was to analyze the cognitive and contextual factors that could limit educational inclusion. Eighty-three autistic patients (3-18years old; 73 males and 10 females) with childhood autism, atypical autism or Asperger's syndrome (criteria from the International Classification of Diseases-10) without mental retardation and in education were assessed at the Alpine Centre for Early Diagnosis of Autism. The sample included 45 subjects with childhood autism, 12 subjects with atypical autism and 26 subjects with Asperger's syndrome. The diagnosis was based on the Autism Diagnostic Interview Revised (ADI-R), in accordance with the recommendations of the HAS, the Autism Diagnostic Observation Schedule (ADOS) and the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV). Our results showed that childhood autism and atypical autism were mainly found in nursery and primary school, whereas Asperger's syndrome was mainly found in secondary school (Chi(2)=18.23; df=6; PWISC-IV also differed: the Verbal Comprehension Index (VCI) and Working Memory Index (WMI) were higher for Asperger's syndrome than for childhood autism and atypical autism (respectively, F=23.11, PWISC-IV, along a continuum that ranges from childhood autism (more needs and deficits) to atypical autism to Asperger's syndrome. The Verbal Comprehension Index (VCI) and the Processing Speed Index (PSI) could be used to evaluate the number of hours of support needed by children and to better target the deficits and

  5. Psychomotor retardation and externally oriented thinking in major depression

    Directory of Open Access Journals (Sweden)

    Luca M

    2013-05-01

    Full Text Available Maria Luca,1 Antonina Luca,2 Carmela Calandra11Department of Medical and Surgery Specialties, Psychiatry Unit of the University Hospital “Policlinico-Vittorio Emanuele” of Catania (Sicily, Italy; 2Department of Neuroscience of the University Hospital “Policlinico-Vittorio Emanuele” of Catania (Sicily, ItalyObjective: To investigate possible correlations between the tendency towards alexithymia and the depressive state, globally and with regard to the Toronto Alexithymia scale (TAS-20 subscales and the Hamilton rating scale for depression (HAM-D subscales.Methods: 75 patients, suffering from Unipolar Depression, were assessed through the HAM-D and the TAS-20 and compared to the control group (n = 63. Both groups were divided into two subgroups (30–60 years old; 61–80 years old. Correlations between the tendency towards alexithymia and depressive symptoms, globally and with regard to the TAS-20 subscales and the HAM-D subscales, were investigated.Results: With regard to patients, a positive correlation was found between: the HAM-D total score and the TAS-20 total score; the HAM-D factor V (psychomotor retardation and the TAS-20 total score; the TAS-20 subscale III (externally oriented thinking and the HAM-D total score. In addition a positive correlation between the HAM-D factor V and the TAS-20 subscales I and III was found and confirmed among females. In patients aged 30–60 years, the HAM-D factor V was correlated with all the TAS-20 subscales. As to the control group, a positive correlation was found between: the HAM-D factor I (anxiety/somatization and the TAS-20 total score; the TAS-20 subscale I and the HAM-D total score; the HAM-D factor I and the TAS-20 subscale. The latter was confirmed in the control group aged 30–60 years.Conclusion: The link between alexithymia and affective symptoms has been confirmed in the patients and in the control group. An interesting data is the correlation between psychomotor retardation and

  6. VOCABULARY PROBLEMS OF THE LIGHTLY MENTALLY RETARDED SCHOOL AGED CHILDREN

    Directory of Open Access Journals (Sweden)

    Vesna KOSTIC

    2000-06-01

    Full Text Available The main research objectives are the problems in the vocabulary of school aged, lightly mentally retarded children. Results of the research indicate which are the most important factors that have impact of the vocabulary and language competence of these persons. The research variables are: sex, IQ, chronological age and school age. Comics-like stories were used as an examination instrument in this research. Their interpretation is helpful in determining the vocabulary level of every single examine. At the end of the research some suggestions are presented, whose goal is to enrich children's vocabulary.

  7. Wheeler and Feynman electrodynamics within the framework of retarded causality

    Energy Technology Data Exchange (ETDEWEB)

    Yaremko, Yu [Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv (Ukraine)

    2002-11-08

    A frontal collision of two point-like charged particles which are asymptotically free in the remote past and in the distant future is considered. Ten conserved quantities corresponding to the symmetry of a closed system of particles and electromagnetic field under the Poincare group are expressed in terms of particle variables. It is shown that an interference of outgoing electromagnetic waves (retarded Lienard-Wiechert solutions) ensures the action of the field of one source on another (mutual interaction). The combination of wave motions accords with the modified Wheeler and Feynman absorber theory of radiation where (acausal) 'perfect absorption' is replaced by an interference phenomenon.

  8. Psychomotor retardation in a girl with complete growth hormone deficiency.

    Science.gov (United States)

    Dayal, Devi; Malhi, Prabhjot; Kumar Bhalla, Anil; Sachdeva, Naresh; Kumar, Rakesh

    2013-01-01

    Infants with complete growth hormone deficiency may suffer from psychomotor retardation in addition to severe growth failure. Without replacement therapy, they may have a compromised intellectual potential manifesting as learning disabilities and attention-deficit disorders in later life. In this communication, we discuss an infant who showed improvement in physical growth after growth hormone therapy but her psychomotor skills did not improve probably due to late start of treatment. There is a need to start growth hormone therapy as early as possible in infants with complete growth hormone deficiency to avoid adverse effects on psychomotor and brain development.

  9. Persistence, bioaccumulation, and toxicity of halogen-free flame retardants.

    Science.gov (United States)

    Waaijers, Susanne L; Kong, Deguo; Hendriks, Hester S; de Wit, Cynthia A; Cousins, Ian T; Westerink, Remco H S; Leonards, Pim E G; Kraak, Michiel H S; Admiraal, Wim; de Voogt, Pim; Parsons, John R

    2013-01-01

    Polymers are synthetic organic materials having a high carbon and hydrogen content, which make them readily combustible. Polymers have many indoor uses and their flammability makes them a fire hazard. Therefore, flame retardants (FRs) are incorporated into these materials as a safety measure. Brominated flame retardants (BFRs), which accounted for about 21% of the total world market of FRs, have several unintended negative effects on the environment and human health. Hence, there is growing interest in finding appropriate alternative halogen-free flame retardants (HFFRs). Many of these HFFRs are marketed already, although their environ- mental behavior and toxicological properties are often only known to a limited extent, and their potential impact on the environment cannot yet be properly assessed. Therefore, we undertook this review to make an inventory of the available data that exists (up to September 2011) on the physical-chemical properties, pro- duction volumes, persistence, bioaccumulation, and toxicity (PBT) of a selection of HFFRs that are potential replacements for BFRs in polymers. Large data gaps were identified for the physical-chemical and the PBT properties of the reviewed HFFRs. Because these HFFRs are currently on the market, there is an urgent need to fill these data gaps. Enhanced transparency of methodology and data are needed to reevaluate certain test results that appear contradictory, and, if this does not provide new insights, further research should be performed. TPP has been studied quite extensively and it is clearly persistent, bioaccumulative, and toxic. So far, RDP and BDP have demonstrated low to high ecotoxicity and persistence. The compounds ATH and ZB exerted high toxicity to some species and ALPI appeared to be persistent and has low to moderate reported ecotoxicity. DOPO and MPP may be persistent, but this view is based merely on one or two studies, clearly indicating a lack of information. Many degradation studies have been

  10. Intumescent Biobased-Polylactide Films to Flame Retard Nonwovens

    Directory of Open Access Journals (Sweden)

    Christelle Reti

    2009-06-01

    Full Text Available The work focuses on the development of a newprocess to flame retard nonwovens, using films basedon renewable resources. Films consist in intumescentformulations of polylactic acid (PLA, ammoniumpolyphosphate (APP blended with lignin or starchand are coated on hemp or wool nonwovens. Theobjective of this study was to investigate the fireretardant and mechanical properties of textilesprotected by FR PLA films for potential use inbuilding applications. Horizontal and vertical flamespread tests as well as cone calorimetry tests showthat flammability properties of nonwovens aresignificantly improved. Better mechanical propertiesare also obtained with coated nonwovens.

  11. Chromosomal abnormalities associated with mental retardation in female subjects.

    Science.gov (United States)

    Dutta, Samikshan; Shaw, Jyothi; Sinha, Swagata; Mukhopadhyay, Kanchan

    2009-01-01

    Chromosomal abnormalities are thought to be the most common cause of mental retardation (MR). However, apart from a few selected types with typical aneuploidy, like Downs syndrome, Klinefelter syndrome, Turner syndrome, etc., the frequency of detectable chromosomal abnormalities in association with idiopathic MR is very low. In this study, we have investigated chromosomal abnormalities in female MR subjects (n = 150) by high-resolution GTG banding. Of them, 30 cases were diagnosed as Downs syndrome. Among the remaining (n = 120), chromosomal abnormalities/marked polymorphisms were detectable in only three MR cases (0.025).

  12. Wheeler and Feynman electrodynamics within the framework of retarded causality

    CERN Document Server

    Yaremko, Yu

    2002-01-01

    A frontal collision of two point-like charged particles which are asymptotically free in the remote past and in the distant future is considered. Ten conserved quantities corresponding to the symmetry of a closed system of particles and electromagnetic field under the Poincare group are expressed in terms of particle variables. It is shown that an interference of outgoing electromagnetic waves (retarded Lienard-Wiechert solutions) ensures the action of the field of one source on another (mutual interaction). The combination of wave motions accords with the modified Wheeler and Feynman absorber theory of radiation where (acausal) 'perfect absorption' is replaced by an interference phenomenon.

  13. Wheeler and Feynman electrodynamics within the framework of retarded causality

    Science.gov (United States)

    Yaremko, Yu

    2002-11-01

    A frontal collision of two point-like charged particles which are asymptotically free in the remote past and in the distant future is considered. Ten conserved quantities corresponding to the symmetry of a closed system of particles and electromagnetic field under the Poincaré group are expressed in terms of particle variables. It is shown that an interference of outgoing electromagnetic waves (retarded Liénard-Wiechert solutions) ensures the action of the field of one source on another (mutual interaction). The combination of wave motions accords with the modified Wheeler and Feynman absorber theory of radiation where (acausal) 'perfect absorption' is replaced by an interference phenomenon.

  14. Stability of 2-body orbits in retarded gravitation theory (RGT)

    CERN Document Server

    Raju, C K

    2015-01-01

    The recently formulated retarded gravitation theory (RGT) explains the non-Newtonian velocities of stars in spiral galaxies, *without any new hypothesis*, and may hence be tested even in the laboratory. However, doubts have been expressed that those higher rotation velocities in RGT may be due to instabilities. We resolve these doubts by solving the full functional differential equations of RGT for a model 2-body planetary system. The solution is stable and closely agrees with the Newtonian solution for this planetary case. Thus, the big difference between RGT and Newtonian gravity for a spiral galaxy is not due to any instability in RGT.

  15. Appropriate classification of obesity of mentally retarded adults.

    Science.gov (United States)

    Fox, R; Burkhart, J E; Rotatori, A F

    1983-07-01

    Triceps skinfold thickness and body weight measures were obtained for 44 female and 40 male mentally retarded adults participating in a sheltered workshop setting. Subjects' relative weights and skinfold thicknesses were found to correlate reasonably well for females and males, rs = .88 and .59, respectively. Use of only height and weight tables for determining the presence of obesity, however, resulted in 22.5 percent of the males and 13.7 percent of the females being misclassified as nonobese. The distinction between overweight and obesity was discussed. Clinical/research implications of the findings were delineated.

  16. Law & psychiatry: mental retardation and the death penalty: after Atkins.

    Science.gov (United States)

    Appelbaum, Paul S

    2009-10-01

    In Atkins v. Virginia the U.S. Supreme Court declared execution of persons with mental retardation to constitute cruel and unusual punishment, and thus to be unconstitutional under the Eighth Amendment. However, the Court left all considerations regarding how to implement the decision explicitly to the states. Since Atkins was decided in 2002, legislatures, courts, and mental health experts have struggled with its implementation, highlighting the complexities that can arise when the courts base legal rules on clinical findings. This column reviews the Atkins case and considers the challenges associated with a clinical determination that can have life-or-death consequences for capital defendants.

  17. Fabrication of Cellulose Nanofiber/AlOOH Aerogel for Flame Retardant and Thermal Insulation

    OpenAIRE

    Bitao Fan; Shujun Chen; Qiufang Yao; Qingfeng Sun; Chunde Jin

    2017-01-01

    Cellulose nanofiber/AlOOH aerogel for flame retardant and thermal insulation was successfully prepared through a hydrothermal method. Their flame retardant and thermal insulation properties were investigated. The morphology image of the cellulose nanofiber/AlOOH exhibited spherical AlOOH with an average diameter of 0.5 μm that was wrapped by cellulose nanofiber or adhered to them. Cellulose nanofiber/AlOOH composite aerogels exhibited excellent flame retardant and thermal insulation propertie...

  18. Two subtelomeric chromosomal deletions in forty-six children with idiopathic mental retardation

    Institute of Scientific and Technical Information of China (English)

    李荣; 赵正言

    2004-01-01

    @@ Mental retardation (MR) affects approximately 3% of the population. In infancy and early childhood, mental retardation often presents as developmental delay. Unexplained MR is responsible for more than half of all cases.1,2 There is some evidence that subtle chromosomal rearrangements involved in subtelomeric regions (gene-rich regions), resulting in segmental aneuploidy and gene-dosage imbalance, are significant unrecognized causes of idiopathic mental retardation (IMR).3-10

  19. Diagnosis and treatment of mental illness in mentally retarded children: a developmental model.

    Science.gov (United States)

    Dosen, A

    1989-01-01

    Attempts have been made in recent years to discover the roots of psychiatric disorders in mentally retarded children by employing a developmental approach in which the child, not the handicap, is brought more clearly into focus. This paper provides a brief overview of the developmental model that has proven useful for the author in the psychiatric diagnosis of mentally retarded children. Application of this model to the treatment of mentally ill-mentally retarded children is also addressed.

  20. Combining cone calorimeter and PCFC to determine the mode of action of flame retardant additives

    OpenAIRE

    LOPEZ CUESTA, José-Marie; Sonnier, Rodolphe; Ferry, Laurent; Longuet, Claire; Laoutid, Fouad; Friedrich, Blandine; Laachachi, Abdelghani

    2011-01-01

    Abstract The flammability of various flame retarded formulations containing different hydrated mineral fillers and/or phosphorous compounds and/or carbon nanotubes has been investigated using both cone calorimeter and PCFC. A method was proposed to evaluate the barrier effect of the flame retardant additives. This method is based on the fact that PCFC is non sensitive to physical flame retardant effects while both chemical and physical phenomena have a great effect on cone calorime...

  1. 膨胀型沥青阻燃剂阻燃性能研究%On Flame Retardant Performance of Intumescent Asphalt Flame Retardant

    Institute of Scientific and Technical Information of China (English)

    凌天清; 张睿卓; 宁华宇; 袁明

    2011-01-01

    Based on the flame-retardant mechanism of modified asphalt and requests and development trend of flame retard-ants, the paper chose IFR to make flame-retardant asphalt. Indicators as limiting oxygen index, synergistic efficiency and flame retardant value were employed to evaluate the flame retardant effectiveness of SBS modified asphalt. After analyzing the flammability of a dollar flame-retardant, binary formulation, ternary formulation system, the optimum composite ratio was determined.%在分析阻燃沥青阻燃机理的基础上,结合阻燃剂的使用要求及发展趋势,选用膨胀型阻燃剂IFR制备阻燃沥青.采用极限氧指数、协同效率和阻燃价值等指标评价了阻燃剂对SBS改性沥青的阻燃效果,通过分析单一阻燃剂、二元复配、三元复配体系的阻燃效果,确定膨胀型阻燃体系的最佳复配比.

  2. Recent Developments in Halogen Free Flame Retardants for Epoxy Resins for Electrical and Electronic Applications

    Directory of Open Access Journals (Sweden)

    Manfred Döring

    2010-08-01

    Full Text Available The recent implementation of new environmental legislations led to a change in the manufacturing of composites that has repercussions on printed wiring boards (PWB. This in turn led to alternate processing methods (e.g., lead-free soldering, which affected the required physical and chemical properties of the additives used to impart flame retardancy. This review will discuss the latest advancements in phosphorus containing flame retardants for electrical and electronic (EE applications and compare them with commercially available ones. The mechanism of degradation and flame retardancy of phosphorus flame retardants in epoxy resins will also be discussed.

  3. Effect of Flame Retardant Containing Phosphorus and Silicone on Thermal Performance of PC/ABS

    Institute of Scientific and Technical Information of China (English)

    WEI Ping; WU Dan; ZHONG Hanfang; DU Jianxin

    2009-01-01

    A flame retardant (DPA-SiN) containing phosphorus, nitrogen and silicon elements was synthesized. The halogen free flame retardant was incorporated into PC/ABS to improve its flame retardancy. The flame-retardant properties of the PC/ABS/DPA-SiN blends were estimated bylimiting oxygen index (LOI) values and CONE Calorimeter, while thermal stabilities were investi-gated through thermo gravimetric analysis (TGA). The PC/ABS/DPA-SiN blends were thermally de-graded at 400 ℃ for different amounts of time and studied by Fourier transform infrared spectros-copy (FTIR) to better understand the degradation behavior of PC/ABS/DPA-SiN.

  4. Systematic Recording of Behaviors and Skills of Retarded and Psychotic Children

    Science.gov (United States)

    Wing, Lorna; Gould, Judith

    1978-01-01

    The reliability of the Children's Handicaps, Behavior and Skills structured interview schedule, intended to elicit information concerning mentally retarded or psychotic children, was investigated. (Author/SBH)

  5. Characterization of organophosphorus flame retardants' sorption on building materials and consumer products

    Science.gov (United States)

    Liu, Xiaoyu; Allen, Matthew R.; Roache, Nancy F.

    2016-09-01

    Better understanding the transport mechanisms of organophosphorus flame-retardants (OPFRs) in the residential environment is important to more accurately estimate their indoor exposure and develop risk management strategies that protect human health. This study describes an improved dual small chamber testing method to characterize the sorption of OPFRs on indoor building materials and consumer products. The OPFRs studied were tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP). The test materials and products used as sinks include concrete, ceiling tile, vinyl flooring, carpet, latex painted gypsum wallboard, open cell polyurethane foam, mattress pad and liner, polyester clothing, cotton clothing, and uniform shirt. During the tests, the amount of OPFRs absorbed by the materials at different exposure times was determined simultaneously. OPFRs air concentrations at the inlet and inside the test chamber were monitored. The data were used to rank the sorption strength of the OPFRs on different materials. In general, building materials exhibited relatively stronger sorption strength than clothing textiles. The material-air partition and material phase diffusion coefficients were estimated by fitting a sink model to the sorption concentration data for twelve materials with three OPFRs. They are in the range of 2.72 × 105 to 3.99 × 108 (dimensionless) for the material-air partition coefficients and 1.13 × 10-14 to 5.83 × 10-9 (m2/h) for the material phase diffusion coefficients.

  6. Electrophoretic Retardation of Colloidal Particles in Nonpolar Liquids

    Directory of Open Access Journals (Sweden)

    Filip Strubbe

    2013-04-01

    Full Text Available We have measured the electrophoretic mobility of single, optically trapped colloidal particles, while gradually depleting the co-ions and counterions in the liquid around the particle by applying a dc voltage. This is achieved in a nonpolar liquid, where charged reverse micelles act as co-ions and counterions. By increasing the dc voltage, the mobility first increases when the concentrations of co-ions and counterions near the particle start to decrease. At sufficiently high dc voltage (around 2 V, the mobility reaches a saturation value when the co-ions and counterions are fully separated. The increase in mobility is larger when the equilibrium ionic strength is higher. The dependence of the experimental data on the equilibrium ionic strength and on the applied voltage is in good agreement with the standard theory of electrophoretic retardation, assuming that the bare particle charge remains constant. This method is useful for studying the electrophoretic retardation effect and charging mechanisms for nonpolar colloids, and it sheds light on previously unexplained particle acceleration in electronic ink devices.

  7. Engineering Biodegradable Flame Retardant Wood-Plastic Composites

    Science.gov (United States)

    Zhang, Linxi

    Wood-plastic composites (WPCs), which are produced by blending wood and polymer materials, have attracted increasing attentions in market and industry due to the low cost and excellent performance. In this research, we have successfully engineered WPC by melt blending Polylactic Acid (PLA) and Poly(butylene adipate-co-terphthalate) (PBAT) with recycled wood flour. The thermal property and flammability of the composite are significantly improved by introducing flame retardant agent resorcinol bis(biphenyl phosphate) (RDP). The mechanical and morphological properties are also investigated via multiple techniques. The results show that wood material has increased toughness and impact resistance of the PLA/PBAT polymer matrix. SEM images have confirmed that PLA and PBAT are immiscible, but the incompatibility is reduced by the addition of wood. RDP is initially dispersed in the blends evenly. It migrates to the surface of the sample after flame application, and serves as a barrier between the fire and underlying polymers and wood mixture. It is well proved in the research that RDP is an efficient flame retardant agent in the WPC system.

  8. Preliminary Study of Mental Retardation in Rovira (Tolima, Colombia

    Directory of Open Access Journals (Sweden)

    Luis Gustavo Celis

    2008-07-01

    Full Text Available limitationsin performance, significant deficiencyin intelligence and adaptative behavior, causingclinical and social disability. Most patients withmental retardation in Colombia do not receiveclinical genetics evaluation. The aims of thepresent study are to evaluate and characterizea group of patients with mental retardationfrom the population of Rovira. The presentstudy included twenty five patients with mentalretardation from Rovira (Tolima whichwere studied by clinical examination, metabolicscreening (ferric chloride, nitrosonaphtol,silver nitroprusiate, dinitrophenylhydrazineand benedict and cytogenetics (G-Bandingkariotype. Pesticide detection was perfomedby random sampling of water and tomatoes intwenty different places of water distribution,the center of the town and crop fields. A familywith three affected sibs (two females, onemale with mental retardation was identified,suggesting a genetic component. Metabolicscreening was negative and karyotypes werenormal. The analyses performed for organophosphateswere positive in 100% of the samples.Carbamates were positive in 60% of thewater source and 100% of tomato samples. Allthe samples tested were negative for organochlorides.Further studies as molecular fragile-X test, will be performed.

  9. Retarded Fields of Null Particles and the Memory Effect

    CERN Document Server

    Tolish, Alexander

    2014-01-01

    We consider the retarded solution to the scalar, electromagnetic, and linearized gravitational field equations in Minkowski spacetime, with source given by a particle moving on a null geodesic. In the scalar case and in the Lorenz gauge in the electromagnetic and gravitational cases, the retarded integral over the infinite past of the source does not converge as a distribution, so we cut off the null source suitably at a finite time $t_0$ and then consider two different limits: (i) the limit as the observation point goes to null infinity at fixed $t_0$, from which the ``$1/r$'' part of the fields can be extracted and (ii) the limit $t_0 \\to - \\infty$ at fixed ``observation point.'' The limit (i) gives rise to a ``velocity kick'' on distant test particles in the scalar and electromagnetic cases, and it gives rise to a ``memory effect'' (i.e., a permanent change in relative separation of two test particles) in the linearized gravitational case, in agreement with previous analyses. Although the second limit does...

  10. Potential estrogenic effects of phosphorus-containing flame retardants.

    Science.gov (United States)

    Zhang, Quan; Lu, Meiya; Dong, Xiaowu; Wang, Cui; Zhang, Chunlong; Liu, Weiping; Zhao, Meirong

    2014-06-17

    As the substitute of polybrominated diphenyl ethers (PBDEs), further assessments about the potential ecological safety and health risks of phosphorus-containing flame retardants (PFRs) are required because the worldwide demand for PFRs has been increasing every year. In this study, we examined the agonistic/antagonistic activity of a group of PFRs by three in vitro models (luciferase reporter gene assay, yeast two-hybrid assay, and E-screen assay). Molecule docking was used to further explain the interactions between ERα and PFRs. Data from luciferase reporter gene analysis showed three members of the nine tested PFRs significantly induced estrogenic effects, with the order of TPP > TCP > TDCPP, while TCEP and TEHP have remarkable antiestrogenic properties with calculated REC20 and RIC20 values of 10(-6) M or lower. Results from the luciferase reporter gene method are generally consistent with results obtained from the yeast two-hybrid assay and E-screen, except for the positive estrogenic activity of TBP in E-screen testing. Docking results showed that binding between ligands and ERα was stabilized by hydrophobic interactions. As a proposed alternative for brominated flame retardant, PFRs may have anti/estrogenic activity via ERα at the low dose typical of residue in environmental matrix or animals. PFRs with a short chain, halogen, and benzene ring in the substituent group tend to be estrogenic. Our research suggests that comprehensive evaluations, including health and ecological assessments, are required in determining whether PFRs are preferable as an emerging industrial substitute.

  11. Modeling mechanical effects on promotion and retardation of martensitic transformation

    Energy Technology Data Exchange (ETDEWEB)

    Maalekian, Mehran, E-mail: mehran.maalekian@ubc.ca [Department of Materials Engineering, University of British Columbia, 309-6350 Stores Road, Vancouver, B.C. V61Z4 (Canada); Kozeschnik, Ernst [Christian Doppler Laboratory for ' Early Stages of Precipitation' , Institute of Materials Science and Technology, Vienna University of Technology (Austria)

    2011-01-25

    Research highlights: {yields} Compressive elastic stresses up to 250 MPa are applied in continuous cooling. {yields} Using the thermodynamic data and maximum value of the mechanical driving force the predicted increase in M{sub s} ({approx}0.1 K/MPa) is in agreement with experiment {yields} Austenite was deformed plastically at different temperatures (800 deg. C-1100 deg. C). {yields} High deformation temperature (i.e. 1100 deg. C) as well as low plastic strain (i.e. {epsilon}{sub ave} {approx} 30%) do not affect martensite transformation noticeably, whereas lower deformation temperature (e.g. 900 deg. C) and large plastic strain (i.e. {epsilon}{sub ave} {approx} 70%) retards martensite transformation. {yields} The theory of mechanical stabilization predicts the depression of M{sub s}. - Abstract: The influence of compressive stress and prior plastic deformation of austenite on the martensite transformation in a eutectoid steel is studied both experimentally and theoretically. It is demonstrated that martensite formation is assisted by stress but it is retarded when transformation occurs from deformed austenite. With the quantitative modeling of the problem based on the theory of displacive shear transformation, the explanation of the two opposite roles of mechanical treatment prior to or simultaneously to martensite transformation is presented.

  12. Organophosphate ester flame retardant-induced acute intoxications in dogs.

    Science.gov (United States)

    Lehner, Andreas F; Samsing, Francisca; Rumbeiha, Wilson K

    2010-12-01

    Flame retardants have wide industrial applications and are incorporated into articles found in automobiles and home environments, including seat cushions. These compounds differ widely chemically and in their toxic potential. We report here two cases involving dogs following ingestion of car seat cushions impregnated with organophosphate ester fire retardants. Two case reports are presented. Two adult American Pit Bull dogs were presented at an emergency clinic with acute signs of central nervous system excitation including seizures. The most severely affected dog died 15 min after presentation, while the less affected dog fully recovered following treatment. In the second case, both a German Shepherd and a Rottweiler were found dead in the morning after they were left in a car overnight. A comprehensive toxicological analysis of samples from both cases revealed the presence of significant amounts (>2 ppm) of tris(2-chloroethyl)phosphate (TCEP) in stomach contents. This compound is a known inducer of epileptic seizures. Some other structurally related organophosphate ester compounds were found, and their role in the acute intoxications reported here is not known and remains to be determined. This is the first report linking acute deaths in dogs to the ingestion of car seat cushions found to contain large amounts of TCEP, an organophosphate ester compound. It is highly likely that this compound caused death through its known seizure-inducing activity.

  13. EVALUASI RENCANA KINERJA KOLAM RETENSI (RETARDING BASIN DALAM UPAYA PENGENDALIAN BANJIR TUKAD MATI DI KOTA DENPASAR

    Directory of Open Access Journals (Sweden)

    I G. Suryadinata P

    2013-03-01

    Full Text Available Tukad Mati is one of the rivers in the province of Bali that unfolds and flows in Badung regency and Denpasar. Inundation due to flooding is a problem that often occurs in this region during the rainy season. In an effort to overcome problems of flooding have been many studies carried out so as to produce flood control alternatives such as normalization, diversion channels and retarding basins. Retarding basin is one of flood control alternative that has not been much studied. In this study conducted a simulation of flood prevention alternative with retarding basin at Tukad Mati, by the hydrology approach method and hydraulics using HEC-RAS 4.0 program applications. Simulations performed on the current river flow conditions (existing condition and to the existing conditions with the retarding basin, according to the detail design of retarding basin in the city of Denpasar and evaluate the effectiveness of the retarding basin in the river basin flood control of Tukad Mati. Flood control by retarding basin based on simulations with the 2 (two years flood return period, resulting in a reduction of water level by an average of 0.42 meters or an average of 12% of the maximum water level in the conditions without retarding basin, which occurred in along the grooves on the lower reaches of the retarding basin and inundation waters still occur in some places, particularly in the downstream of Umadui Dam. Economic analysis of both the analysis of Benefits/Cost produces a parameter of BCR, NPV and IRR are not meet the feasibility requirements. The effective retention of retarding basin based on simulation results are 282,630.00 m3 with the ability to flood accommodate for 3-4 hours. In terms of economic development retarding basin is not feasible in terms of comparative costs and benefits

  14. EVALUASI RENCANA KINERJA KOLAM RETENSI (RETARDING BASIN DALAM UPAYA PENGENDALIAN BANJIR TUKAD MATI DI KOTA DENPASAR

    Directory of Open Access Journals (Sweden)

    I G. Suryadinata P

    2013-01-01

    Full Text Available Tukad Mati is one of the rivers in the province of Bali that unfolds and flows in Badung regency and Denpasar. Inundation due to flooding is a problem that often occurs in this region during the rainy season. In an effort to overcome problems of flooding have been many studies carried out so as to produce flood control alternatives such as normalization, diversion channels and retarding basins. Retarding basin is one of flood control alternative that has not been much studied. In this study conducted a simulation of flood prevention alternative with retarding basin at Tukad Mati, by the hydrology approach method and hydraulics using HEC-RAS 4.0 program applications. Simulations performed on the current river flow conditions (existing condition and to the existing conditions with the retarding basin, according to the detail design of retarding basin in the city of Denpasar and evaluate the effectiveness of the retarding basin in the river basin flood control of Tukad Mati. Flood control by retarding basin based on simulations with the 2 (two years flood return period, resulting in a reduction of water level by an average of 0.42 meters or an average of 12% of the maximum water level in the conditions without retarding basin, which occurred in along the grooves on the lower reaches of the retarding basin and inundation waters still occur in some places, particularly in the downstream of Umadui Dam. Economic analysis of both the analysis of Benefits/Cost produces a parameter of BCR, NPV and IRR are not meet the feasibility requirements. The effective retention of retarding basin based on simulation results are 282,630.00 m3 with the ability to flood accommodate for 3-4 hours. In terms of economic development retarding basin is not feasible in terms of comparative costs and benefits

  15. Molecular Design, Graft Polymerization and Performance Evaluation of Radiation Curable Flame Retardant Monomers Derived from Phosphorus-Nitrogen Systems

    Science.gov (United States)

    Edwards, Brian Tyndall

    The textile industry is constantly seeking new technologies to make its production more efficient, economical and environmentally friendly. An exciting new strategy to impart value-added functional finishes to textiles is the use of radiation, such as ultraviolet (UV) light, to drive the polymerization of monomers onto the surface of the substrates. These grafted polymeric layers provide the fiber or fabric with interesting new properties, such as antimicrobial behavior, water and oil repellency or flame retardancy. With the aid of a photoinitiator, UV curing can take place very rapidly and the process is waterless and uses less energy than traditional textile wet processing. With these thoughts in mind, this research explores the molecular design, synthesis, UV induced graft polymerization and performance evaluation of nine phosphorus-based flame retardant monomers for cellulosic cotton substrates. All monomers in this work were easily prepared using one-pot reactions procedures. With the assistance of Irgacure 819 photoinitiator, seven of the nine monomers were shown to simultaneously graft and polymerize onto the surface of cotton fabrics under UV radiation. JMPRTM Pro 10 software was used to explore the effect of variables, such as monomer concentration, photoinitiator concentration and UV exposure time, on the yield of the grafted polymeric layer. Burn testing of the treated fabrics in the vertical, 45° and horizontal orientations showed that all nine monomers were effective flame retardants that function via the condensed phase mechanism by encouraging the formation of nonflammable char. These burn test results were validated by thermogravimetric analysis, which demonstrated quantitatively that all nine monomers strongly promote the generation of a protective char. Finally, scanning electron microscopy was used to examine the surface morphology of the treated fabrics and visualize the grafted polymeric layer.

  16. Halogen Free Flame Retardant Rigid Polyurethane Foam%无卤阻燃聚氨酯外墙保温材料

    Institute of Scientific and Technical Information of China (English)

    胡爽; 翟金国; 叶文; 许肖丽; 陈涛; 林倬仕; 尹亮; 陈崇伟

    2015-01-01

    聚氨酯外墙保温材料( PUF)容易燃烧,本文使用自制无卤膨胀型阻燃剂对PUF进行阻燃改性。阻燃改性提高了材料在高温区的热稳定性,材料的成炭量提高了311%。阻燃聚氨酯保温材料( FRPUF)的总热释放下降了约45%,氧指数( LOI)增加了80%。%The rigid polyurethane foam ( PUF) was combustible. The self-made flame retardant was used to improve the PUF. Results showed that the flame retardant improved the thermal stability of PUF in high temperature phase. The heat release rate reduced 45%, and the LOI increased 80%.

  17. Experimental study on retarding mortar and its application in prestressed concrete

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-ling; SONG Yu-pu; HONG Lei

    2008-01-01

    Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5℃ -35℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investiga-ted. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mecha-nism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded pre-stressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the testwhen retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in prac-tical concrete projects.

  18. These Are Not Children; A Play About Opportunities for the Mentally Retarded.

    Science.gov (United States)

    Alden, Jerome; Johnesse, Adaline

    The play, which involves a mentally retarded youth, his parents, and a rehabilitation counselor, gives dramatic emphasis to the youth's problems in adjusting to the outside world and to the adjustment problems of the parents. The character of Joey is used to demonstrate that the retarded can be helped to lead useful and productive lives and to…

  19. Awareness among Family Members Having Children with Mental Retardation on Relevant Legislations in India

    Science.gov (United States)

    Kuppusamy, Balabaskar; Narayan, Jayanthi; Nair, Deepa

    2012-01-01

    In India, Acts and legislations are in place for persons with mental retardation. Three major Acts namely Rehabilitation Council of India Act (1992), Persons with Disabilities (Equal opportunities, protection of rights and full participation) Act (1995) and National Trust for welfare of persons with Autism, Cerebral Palsy, Mental retardation and…

  20. The Croydon Assessment of Learning Study: Prevalence and Educational Identification of Mild Mental Retardation

    Science.gov (United States)

    Simonoff, Emily; Pickles, Andrew; Chadwick, Oliver; Gringras, Paul; Wood, Nicky; Higgins, Siobhan; Maney, Julie-Ann; Karia, Nisha; Iqbal, Huma; Moore, Anne

    2006-01-01

    Background: Mild mental retardation is an enduring and impairing condition. Its prevalence has varied widely across different studies from 0.5 to over 8%, with higher rates in completely ascertained samples. The current study estimates the prevalence of low IQ in the mental retardation range (intellectual disability) in a population sample and…