scholarly journals High-Efficiency, Flexibility and Lead-Free X-ray Shielding Multilayered Polymer Composites

2020 ◽  
Author(s):  
Zefeng Li ◽  
Wei Zhou ◽  
Xianlong Zhang ◽  
Yue Gao ◽  
Shaoyun Guo
Keyword(s):  
Polymer Composites ◽  
Layer Thickness ◽  
High Efficiency ◽  
Thickness Ratio ◽  
Lead Free ◽  
X Rays ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Number Of Layers ◽  
Ethylene Octene Copolymer

Abstract To overcome the severe toxicity and blind absorption zone of conventional lead-based shielding materials for X-rays in the 70-90 keV range, the lead-free multilayered polymer composites were designed and fabricated. The effects of the direction of incidence of the X-rays and number of layers as well as layer thickness ratio of the (tungsten/ethylene-octene copolymer)/(bismuth/ethylene-octene copolymer) layered composites on their shielding efficiency were studied systematically. Compared to the traditional polymer blending, the multilayered polymer composites exhibited the improved photon attenuation. The multilayered polymer composites (layer thickness ratio was 3:7) with 6 layers had the best X-ray shielding ability. Moreover, the X-ray shielding provided by the multi-layered interfaces and the multiple complementary effect of the absorption within the multilayered structure were firstly proposed based on computer simulations. The multilayered structural design effectively weakened the probability of the X-ray penetration. Therefore, the X-ray shielding capability can be effectively enhanced through increasing number of layers and the synergistic effect of multi-layered interfaces. The experimental results of this study can serve as guidelines for the fabrication of flexibility, lead-free, lightweight and high-efficiency X-ray shielding materials.

scholarly journals High-efficiency, flexibility and lead-free X-ray shielding multilayered polymer composites: layered structure design and shielding mechanism

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zefeng Li ◽  
Wei Zhou ◽  
Xianlong Zhang ◽  
Yue Gao ◽  
Shaoyun Guo
Keyword(s):  
Polymer Composites ◽  
Layer Thickness ◽  
High Efficiency ◽  
Thickness Ratio ◽  
Lead Free ◽  
X Rays ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Number Of Layers ◽  
Ethylene Octene Copolymer

AbstractTo overcome the severe toxicity and blind absorption zone of conventional lead-based shielding materials for X-rays in the 70–90 keV range, the lead-free multilayered polymer composites were designed and fabricated. The effects of the direction of incidence of the X-rays and number of layers as well as layer thickness ratio of the (tungsten/ethylene-octene copolymer)/(bismuth/ethylene-octene copolymer) layered composites on their shielding efficiency were studied systematically. Compared to the traditional polymer blending, the multilayered polymer composites exhibited the improved photon attenuation. The multilayered polymer composites (layer thickness ratio was 3:7) with 6 layers had the best X-ray shielding ability. Moreover, the X-ray shielding provided by the multi-layered interfaces and the multiple complementary effect of the absorption within the multilayered structure were firstly proposed based on computer simulations. The multilayered structural design effectively weakened the probability of the X-ray penetration. Therefore, the X-ray shielding capability can be effectively enhanced through increasing number of layers and the synergistic effect of multi-layered interfaces. The experimental results of this study can serve as guidelines for the fabrication of flexibility, lead-free, lightweight and high-efficiency X-ray shielding materials.

Structural characterization and thermal stability of W/Si multilayers

1993 ◽  
Vol 8 (10) ◽  
pp. 2600-2607 ◽  
Author(s):  
M. Brunel ◽  
S. Enzo ◽  
M. Jergel ◽  
S. Luby ◽  
E. Majkova ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Layer Thickness ◽  
Thickness Ratio ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Transmission Electron ◽  
Thermal Stability Of ◽  
Beam Deposition

Tungsten/silicon multilayers with tungsten layers of a thickness of 1–2 nm were prepared by means of electron beam deposition. Their structure and thermal stability under rapid thermal annealing were investigated by a combination of x-ray diffraction techniques and cross-sectional transmission electron microscopy. The crystallization behavior was found to depend on the interdiffusion and mixing at the tungsten/silicon interfaces during deposition as well as during annealing. The as-deposited tungsten/silicon multilayers were amorphous and remained stable after annealing at 250 °C/40 s. Interdiffusion and crystallization occurred after annealing all samples from 500 °C/40 s up to 1000 °C/20 s. By performing the same heat treatment in the tungsten/silicon multilayers, the formation of body-centered cubic W was observed with a layer thickness ratio δW/δsi = 1, whereas tetragonal WSi2 was detected in tungsten/silicon multilayers with a layer thickness ratio of δw/δsi ∼0.25. This dependence of the crystallization products on the layer thickness ratio δw/δsi originates from the different phenomena of interdiffusion and mixing at the tungsten/silicon interfaces. The possible formation of bcc tungsten as a first stage of crystallization of tungsten-silicon amorphous phase, rich in tungsten, is discussed.

Laminated Si3N4/SiC Composites with Self-Sealed Structure

2007 ◽  
Vol 280-283 ◽  
pp. 1873-1876 ◽  
Author(s):  
Zhengbo Yu ◽  
Zoran Krstić ◽  
Vladimir D. Krstić
Keyword(s):  
Layer Thickness ◽  
Fracture Behavior ◽  
Thickness Ratio ◽  
X Ray Diffraction ◽  
Relative Thickness ◽  
X Ray ◽  
Layer Thickness Ratio ◽  
Sic Composites ◽  
Physical And Chemical ◽  
Work Of Fracture

Self-sealed laminar Si3N4/SiC composites, with different cross-section shapes and various thickness ratios of Si3N4 to SiC, have been fabricated. The laminates consist alternately of thicker Si3N4 layers ranging from 100 to 500µm and thinner SiC layers ranging from 6 to 15µm after sintering. Preliminary results indicate that SiC thin layer forms during sintering according to the reaction Si3N4 + 3C ® 3SiC + 2N2, which is confirmed by X-ray diffraction. An excellent physical and chemical compatibility between Si3N4 and SiC layers was observed. The self-sealed Si3N4/SiC composites not only demonstrate a superb resistance to delamination, usually associated with the plate-form ones, but also show a high damage-tolerance behavior. The laminated Si3N4/ SiC composite with a layer thickness ratio of Si3N4 to SiC of approximately 40 gives the highest value of work of fracture (WOF) of approximately 406 kJ/m3, whereas the highest toughness of 21 MPam1/2 was achieved at the layer thickness ratio of 50. The effects of the relative thickness of Si3N4 and SiC layers on the densification of the laminates are examined and fracture behavior and microstructure of the Si3N4/SiC laminates discussed.

Tuning Negative Capacitance in PbZr0.2Ti0.8O3/SrTiO3 Heterostructures via Layer Thickness Ratio

2021 ◽  
Vol 16 (3) ◽  
Author(s):  
Yifei Hao ◽  
Tianlin Li ◽  
Yu Yun ◽  
Xin Li ◽  
Xuegang Chen ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Thickness Ratio ◽  
Negative Capacitance ◽  
Layer Thickness Ratio

scholarly journals Future developments for macromolecular crystallography at the CLS

2014 ◽  
Vol 70 (a1) ◽  
pp. C1737-C1737
Author(s):  
Pawel Grochulski ◽  
Miroslaw Cygler ◽  
Michel Fodje ◽  
Shaunivan Labiuk ◽  
James Gorin ◽  
...  
Keyword(s):  
High Efficiency ◽  
Single Photon ◽  
Temporal Stability ◽  
Small Samples ◽  
X Rays ◽  
Macromolecular Crystallography ◽  
Optical Elements ◽  
X Ray ◽  
Small Crystals ◽  
Reported Data

The Canadian Macromolecular Crystallography Facility (CMCF) at the Canadian Light Source (CLS) is a suite of fully automated beamlines, 08ID-1 and 08B1-1 [1]. It serves over 60 Canadian groups plus academic and commercial users in the US. Besides remote data collection, we offer Mail-In service where data are collected by CMCF staff. Beamline 08B1-1 has been in operation since 2011 and beamline 08ID-1 since 2006. When beamline 08ID-1 was designed, over 10 years ago, small crystals were defined as having sizes of 50-100 μm. Today, the most challenging experiments require more intense X-ray beams that can be focused to accommodate much smaller crystal sizes of less than 5 μm with flux on the order of 10^11 photons/s. To reach these stringent parameters, a new more powerful source of X-rays will be required, which will be provided by a longer small-gap in-vacuum undulator (SGU). To accommodate the higher power levels and to focus X-rays to a smaller focal spot with a high degree of spatial and temporal stability, the existing X-ray optical elements need to be upgraded. The remaining components of the project include a 5-axis alignment table for improving alignment of small samples with the microbeam, a high-efficiency robotic sample-changer and a single-photon X-ray detector. Several options for the new design will be discussed. These developments are consistent with the current direction of structural biology research at the CLS [2]. Since 2006 over 225 (240) papers and 400 (444) PDB deposits reported data collected at beamline 08ID-1. Parentheses indicate the total number for the CMCF. Many of these have been published in very high impact journals such as N. Engl. J. Med., Nature, Cell, Science, PNAS, among others (http://cmcf.lightsource.ca/publications/).

Influence of Layer-Thickness Ratio on Magnetic Properties in F-La2/3Ca1/3MnO3/AF-La1/3Ca2/3MnO3 Bilayers

2012 ◽  
Vol 25 (7) ◽  
pp. 2193-2198 ◽  
Author(s):  
P. Prieto ◽  
L. Marín ◽  
S. M. Diez ◽  
J.-G. Ramirez ◽  
M. E. Gómez
Keyword(s):  
Magnetic Properties ◽  
Layer Thickness ◽  
Thickness Ratio ◽  
Layer Thickness Ratio

The Characteristic X-Rays from Boron and Beryllium

1965 ◽  
Vol 9 ◽  
pp. 456-470 ◽  
Author(s):  
R. C. Ehlert ◽  
R. A. Mattson
Keyword(s):  
Proportional Counter ◽  
Soap Film ◽  
Peak Height ◽  
Half Width ◽  
Emission Lines ◽  
X Rays ◽  
Pure Element ◽  
X Ray ◽  
Number Of Layers ◽  
Lead Stearate

AbstractLead stearate and lead lignocerate multilayer soap-film structures are used to disperse the K emission lines of boron and beryllium respectively. Data are presented showing the dependence of the peak height and half-width on the number of layers in the lignocerate structure. Spectra are presented and compared for the pure element and several compounds of each element. Both electron and X-ray excitation are used. Detection is by a thin-window flow-proportional counter.

Experimental Study of Wave Loading by Internal Solitary Waves on a Submerged Slender Body

2020 ◽  
Author(s):  
Meng Ji ◽  
Ke Chen ◽  
Yunxiang You ◽  
Ruirui Zhang
Keyword(s):  
Layer Thickness ◽  
Solitary Waves ◽  
Wave Amplitude ◽  
Prediction Method ◽  
Thickness Ratio ◽  
Experimental Results ◽  
Slender Body ◽  
Internal Solitary Waves ◽  
Wave Loads ◽  
Layer Thickness Ratio

Abstract Although ocean structures are complex, they all can be disassembled into a number of simple-shaped parts. One common shape is the slender body mentioned in this paper, and we focus on studying the mechanism of this shape. Experiments were carried out to study features of wave loads exerted by internal solitary waves (ISWs) on a submerged slender body. ISWs were generated by a piston-type wave maker in a large-type density stratified two-layer fluid wave flume. Using a three-component force transducer, the force variation of three degree of freedom (DOF) on the model was recorded. A satisfactory prediction method is established for ISWs on a submerged slender body based on internal solitary wave theory, Morison equation and pressure integral. Calculations based on this new prediction method are in good agreement with the experimental results. The experimental results and calculations show that, different incident angles, wave amplitude and layer thickness ratio have great effects on the wave loads, especially transverse incident waves bring much more severely influence. Besides the forces increase linearly with the wave amplitude becoming larger, and the maximums of the horizontal forces increase with the layer thickness ratio increasing.

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