scholarly journals Spectroscopic Investigation of Degradation Reaction Mechanism in γ-Rays Irradiation of HDPE

2020 ◽  
Vol 11 (2) ◽  
pp. 9405-9419
Keyword(s):  
Reaction Mechanism ◽  
Chain Scission ◽  
Product Formation ◽  
X Ray Diffraction ◽  
Γ Irradiation ◽  
Ketone Carbonyl ◽  
Degradation Reaction ◽  
Γ Rays ◽  
Xrd Techniques ◽  
Dose Dependent

Radiation damage and reaction mechanism of product formation due to γ-irradiation in high-density polyethylene (HDPE) have been studied by Fourier transform infrared (FTIR), UV-vis spectroscopic, and x-ray diffraction (XRD) techniques. A Co60gamma source (with a dose rate of 1.707 kGy/hr) has been used up to the total dose of 570 kGy. There are dose-dependent changes in the polymer. The optical band gap decreases with the increase of the γ-irradiation dose. Formations of unsaturation centers have been observed. FTIR observed that a lower dose of γ-irradiation induces the formation of an unsaturated (-C=C-) group and a ketone carbonyl group. Breaking of the C-H bond is more frequent than the breaking of the C-C bond in irradiated HDPE. Crosslinking dominates over chain scission (breaking of C-C bond of the main chain) at a lower dose (100 kGy). There has been no significant influence of γ-irradiation on the crystalline structure, although crystalline size decreases. Mechanisms of the formation of alkyl, allylic, and polyenyl radicals have been investigated.

Devitrification products of rapidly solidified Ni-Nb amorphous alloys.

1990 ◽  
Vol 48 (4) ◽  
pp. 950-951
Author(s):  
G. A. Bertero ◽  
W.H. Hofmeister ◽  
N.D. Evans ◽  
J.E. Wittig ◽  
R.J. Bayuzick
Keyword(s):  
Electron Microscopy ◽  
Amorphous Structure ◽  
Sulphuric Acid Solution ◽  
X Ray Diffraction ◽  
High Fracture ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Rapidly Solidified ◽  
Electromagnetically Levitated

Rapid solidification of Ni-Nb alloys promotes the formation of amorphous structure. Preliminary results indicate promising elastic properties and high fracture strength for the metallic glass. Knowledge of the thermal stability of the amorphus alloy and the changes in properties with temperature is therefore of prime importance. In this work rapidly solidified Ni-Nb alloys were analyzed with transmission electron microscopy (TEM) during in-situ heating experiments and after isothermal annealing of bulk samples. Differential thermal analysis (DTA), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques were also used to characterize both the solidification and devitrification sequences.Samples of Ni-44 at.% Nb were electromagnetically levitated, melted, and rapidly solidified by splatquenching between two copper chill plates. The resulting samples were 100 to 200 μm thick discs of 2 to 3 cm diameter. TEM specimens were either ion-milled or alternatively electropolished in a methanol-10% sulphuric acid solution at 20 V and −40°C.

One Step Synthesis and Characterization of Zirconia-Graphene Composites

2012 ◽  
Vol 600 ◽  
pp. 174-177 ◽  
Author(s):  
Jian Fei Xia ◽  
Zong Hua Wang ◽  
Yan Zhi Xia ◽  
Fei Fei Zhang ◽  
Fu Qiang Zhu ◽  
...  
Keyword(s):  
Synthesis And Characterization ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Composite ◽  
Transmission Electron ◽  
One Step ◽  
Ft Ir ◽  
Xrd Techniques

Zirconia-graphene composite (ZrO2-G) has been successfully synthesized via decomposition of ZrOCl2•6H2O in a water-isopropanol system with dispersed graphene oxide (GO) utilizing Na2S as a precursor could enable the occurrence of the deposition of Zr4+ and the deoxygenation of GO at the same time. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the samples. It was found that graphene were fully coated with ZrO2, and the ZrO2 existing in tetragonal phase, which resulted in the formation of two-dimensional composite.

Study in performance and morphology of polyamide 12 produced by selective laser sintering technology

2018 ◽  
Vol 24 (5) ◽  
pp. 813-820 ◽  
Author(s):  
Junjie Wu ◽  
Xiang Xu ◽  
Zhihao Zhao ◽  
Minjie Wang ◽  
Jie Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Polarized Light ◽  
Chain Scission ◽  
High Energy ◽  
Laser Sintering ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Polyamide 12

Purpose The purpose of this paper is to investigate the effect of selective laser sintering (SLS) method on morphology and performance of polyamide 12. Design/methodology/approach Crystallization behavior is critical to the properties of semi-crystalline polymers. The crystallization condition of SLS process is much different from others. The morphology of polyamide 12 produced by SLS technology was investigated using scanning electron microscopy, polarized light microscopy, differential scanning calorimetry, X-ray diffraction and wide-angle X-ray diffraction. Findings Too low fill laser power brought about bad fusion of powders, while too high energy input resulted in bad performance due to chain scission of macromolecules. There were three types of crystal in the raw powder material, denoted as overgrowth crystal, ring-banded spherulite and normal spherulite. Originality/value In this work, SLS samples with different sintering parameters, as well as compression molding sample for the purpose of comparison, were made to study the morphology and crystal structure of sintered PA12 in detail.

Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques

2011 ◽  
Vol 465 ◽  
pp. 259-262 ◽  
Author(s):  
M. Rogante ◽  
Pavol Mikula ◽  
Miroslav Vrána
Keyword(s):  
Mechanical Tests ◽  
Substantial Contribution ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
Interface Area ◽  
X Ray ◽  
Coated Materials ◽  
Coating Delamination ◽  
Yield Trends ◽  
Xrd Techniques

The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, thus, a substantial contribution in justifying different cases of failure or else bad performance of coated components due to e.g. the coating delamination or to other occurrences which are not simply interpretable via the conventional mechanical tests or microstructure analyses. The adoption of both neutron diffraction (ND) and X-ray diffraction (XRD) techniques has revealed its usefulness in assessing the RS values in proximity of the coating interface area, respectively, without any layer removal or hole drilling at the extreme surface. In this paper, some real cases of RS determination in coated materials by using these techniques and exploiting their complementarity are described. ND, in particular, is very suitable for crucial applications, where a much different stress situation than that assessed by XRD could be present at some depth below the surface. The results achieved can yield trends adoptable in monitoring of the coating features.

scholarly journals Hepatic Gene Expression Changes in Rats Internally Exposed to Radioactive 56MnO2 Particles at Low Doses

2021 ◽  
Vol 43 (2) ◽  
pp. 758-766
Author(s):  
Bakhyt Ruslanova ◽  
Zhaslan Abishev ◽  
Nailya Chaizhunussova ◽  
Dariya Shabdarbayeva ◽  
Sholpan Tokesheva ◽  
...  
Keyword(s):  
Atomic Bomb ◽  
Kinase Inhibitor ◽  
Biological Effects ◽  
Nuclear Factor Κb ◽  
Internal Exposure ◽  
Whole Body ◽  
Control Group ◽  
Gene Expressions ◽  
Γ Irradiation ◽  
Γ Rays

We have studied the biological effects of the internal exposure to radioactive manganese-56 dioxide (56MnO2), the major radioisotope dust found in soil after atomic bomb explosions. Our previous study of blood chemistry indicated a possible adverse effect of 56MnO2 on the liver. In the present study, we further examined the effects on the liver by determining changes in hepatic gene expressions. Male Wistar rats were exposed to 56MnO2 particles (three groups with the whole-body doses of 41, 90, and 100 mGy), stable MnO2 particles, or external 60Co γ-rays (2 Gy), and were examined together with the non-treated control group on postexposure day 3 and day 61. No histopathological changes were observed in the liver. The mRNA expression of a p53-related gene, the cyclin-dependent kinase inhibitor 1A, increased in 56MnO2 as well as in γ-ray irradiated groups on postexposure day 3 and day 61. The expression of a stress-responsive gene, nuclear factor κB, was also increased by 56MnO2 and γ-rays on postexposure day 3. However, the expression of cytokine genes (interleukin-6 or chemokine ligand 2) or fibrosis-related TGF-β/Smad genes (Tgfb1, Smad3, or Smad4) was not altered by the exposure. Our data demonstrated that the internal exposure to 56MnO2 particles at less than 0.1 Gy significantly affected the short-term gene expressions in the liver in a similar manner with 2 Gy of external γ-irradiation. These changes may be adaptive responses because no changes occurred in cytokine or TGF-β/Smad gene expressions.

Reaction Synthesis and Oxidation Behaviours of Ludwigite

2010 ◽  
Vol 146-147 ◽  
pp. 475-480 ◽  
Author(s):  
Ran Liu ◽  
Xing Juan Wang ◽  
Yong Liang Gao ◽  
Qing Lu ◽  
Xiang Xin Xue
Keyword(s):  
Weight Loss ◽  
Mass Loss Rate ◽  
Mass Gain ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Blast Furnace Smelting ◽  
Isothermal Tg ◽  
Lower Temperature ◽  
Xrd Techniques ◽  
Furnace Smelting

Using ludwigite as raw material, the phase transformation and mass loss rate of ludwigite in the process of oxidizing roasting are investigated by DTA, isothermal TG, scanning electron microscopy (SEM), X-ray diffraction (XRD) techniques. The results showed that magnetite is transformed into hematite, serpentine is decomposed into forsterite at lower temperature (T＜700°C). The weight of ludwigite has a small loss below 600°C. The decomposed of szaibelyite dehydrated and formed into suanite about 700°Cis the main reason of causing ludwigite mass losses. By comparing the curves of ludwigite at different temperature from 700 to 900°C, the process of oxidizing roasting can be divided into three phases: characterized by a period of fast weight loss, and then followed by a mass gain. Finally, weight of sample is no longer change with prolongation of time. The final weight loss is 6.062%, 6.658% and 7.442% respectively for test temperature. Suanite can not be decomposed to form B2O3 and volatilized when the temperature of oxidizing roasting is below 1142 °C. It is found by XRD that paigeite and magnoferrite are the most stable composition without deterioration on oxidizing roasting. The experiment results can provide theoretical references for agglomeration and blast furnace smelting of ludwigite.

Etude par résonance paramagnétique électronique de la radiolyse en phase solide de composés cycliques perfluorés

1970 ◽  
Vol 48 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Claude Chachaty ◽  
Alain Forchioni ◽  
Masaru Shiotani
Keyword(s):  
Electron Spin Resonance ◽  
Solid State ◽  
Relative Intensity ◽  
Transition Point ◽  
Γ Irradiation ◽  
Ring Inversion ◽  
Spin Resonance ◽  
The Matrix ◽  
Γ Rays ◽  
Transition Points

Perfluorocyclohexane (PFCH) and perfluoromethylcyclohexane (PFMCH) have been irradiated in the solid state by γ rays of 60Co. The electron spin resonance (e.s.r.) spectrum of PFCH irradiated at 77 °K corresponds mainly towhich is tumbling in the matrix above 160 °K and disappears at the transition point (180 °K). When γ irradiation is carried out at 200 °K, C6F11• is also produced, but reacts with PFCH giving a radicalsupposed to be [Formula: see text]The e.s.r. spectrum of PFMCH γ irradiated at 77 °K has not been identified; it might be attributable in part to (•C6F11CF3)−. Above 160–170° K, the e.s.r. spectrum corresponds only toThe equal coupling of the four γ fluorines and also the relative intensity 1:4:1 of the three main groups of lines observed above 210 °K suggest that ring inversion occurs with a high rate.We have also studied the radicals [Formula: see text]produced by γ irradiation in the presence of oxygen. The variation of their spectra with temperature, particularly near the transition points, is very characteristic of the motion involved.

scholarly journals Synthesis of (Bi,Pb)-2223 superconductor powder by pechini method

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Guilherme Botega Torsoni ◽  
Cícero Rafael Cena ◽  
Gustavo Quereza de Freitas ◽  
Claudio Luis Carvalho
Keyword(s):  
Pechini Method ◽  
Crystallization Kinetic ◽  
Inorganic Ions ◽  
Precursor Solution ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Powder Morphology ◽  
Chemical Reagents ◽  
Different Temperatures ◽  
Xrd Techniques

In this paper, we present a detailed route of synthesis to produce ceramic superconductor Bi1,6Pb0,4Sr2Ca2Cu3Ox (Bi,Pb)-2223 powder by Pechini method. The obtained polymeric precursor solution was produced by using inexpensive chemical reagents, which showed a great stability for three weeks with high concentration of BPSCCO inorganic ions. The crystallization kinetic of BPSCCO powder was investigated by thermal analysis (DSC/TGA) and X-ray diffraction (XRD) techniques. The thermal treatment of the BPSCCO powder at different temperatures showed that complex phase equilibrium occurs to the system. The three superconductor phases seems to coexist in a large range of temperature, the Bi-2201 phase was crystallized around 500 oC and then, after 840 oC the desirable (Bi,Pb)-2223 phase appears with coexistence of the Bi-2212 phase at low quantity. Finally, the powder morphology was characterized by scanning electron microscopy (SEM), the results point to a typical plate like formation of the grains.

scholarly journals Syntheses, Structures, and Characteristics of Three Metal Complexes Constructed Using Hexacarboxylic Acid

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4431 ◽  
Author(s):  
Lingshu Meng ◽  
Lun Zhao ◽  
Guanlin Guo ◽  
Xin Liu ◽  
Zhijun Liang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Thermogravimetric Analysis ◽  
Coordination Polymers ◽  
Electrochemical Behavior ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Hexadentate Ligand ◽  
Xrd Techniques

In this study, three new 3D coordination polymers (CPs), {[Cd3(L)(H2O)6]·H2O}n (1), {[Cu1.5(L)0.5(bimb)1.5]·5H2O·DMF}n (2), and {[Mn1.5(H3L)(bibp)0.5(H2O)2]·3H2O}n (3) (bimb= 1,3-bis(imidazol-1-yl)benzene, bibp= 1,4-bis((4-imidazol-1-yl)benzyl)piperazine), were prepared under solvothermal or hydrothermal conditions based on a hexadentate ligand (1,3,5-triazine-2,4,6-triamine hexa-acetic acid (H6L)). Structural elucidations were carried out by IR spectra along with single-crystal X-ray diffraction analysis, while thermogravimetric analysis (TGA) (dynamic and isothermal) and XRD techniques were used for property evaluations of the polymers. Furthermore, the fluorescence properties and detection of the Fe3+ ions in 1 were tested at room temperature, and the electrochemical behavior of 2 is also stated in this article.

Sign in / Sign up

Export Citation Format

Share Document