Ultraviolet‑Irradiated All‑Organic Nanocomposites with Polymer Dots for High‑Temperature Capacitive Energy Storage

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems.While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers,the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing.Herein,zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone)to form the all-organic polymer composites for hightemperature capacitive energy storage.Upon ultraviolet irradiation,the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures,which significantly reduces the high-field energy loss of the composites at 200℃.Accordingly,the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm^(−3)at 200℃.Along with outstanding cyclic stability of capacitive performance at 200℃,this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

Study of leakage current degradation based on stacking faults expansion in irradiated SiC junction barrier Schottky diodes

A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky(JBS)diodes under heavy ion irradiation.We propose and verify that the generation of stacking faults(SFs)induced by the recombination of massive electron-hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results.The irradiation experiment was carried out based on Ta ions with high linear energy transfer(LET)of 90.5 MeV/(mg/cm^(2)).It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20%of the rated reverse voltage.Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes.We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation.Finally,three-dimensional(3D)TCAD simulation was employed to evaluate the excessive electron-hole pairs(EHPs)concentration excited by heavy ion irradiation.It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate.The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.

Thermoluminescent response of gamma irradiated Na^(+)–Cu^(+) ionexchanged silicate glass in large dose range

The introduction of metals into vitreous matrices is the origin of various interesting phenomena;in particular,the presence of copper ions in glass has been the subject of considerable research because of its numerous applications.The ion-exchange process is primarily used to introduce copper ions into glass matrices.The thermoluminescence(TL)of silicate glass was studied to evaluate its potential as gamma-sensitive material for dosimetric applications;the effect of copper doping on the thermoluminescent sensitivity was investigated using the Cu-Na ion-exchange technique for different concentrations and doping conditions,over a wide dose range of 10 mGy to 100 kGy.The results showed that Cu doping significantly improved the sensitivity of the glasses to gamma radiation.After the ion-exchange,two peaks appeared in the glow curves at approximately 175 and 230°C,respectively,which possibly originated from the Cu^(+) centers,along with a weak TL peak at around 320℃.We also attempted to explain the origin of the observed thermoluminescence by exploiting the Electron paramagnetic resonance(EPR)spectra.The results clearly show quenching of the TL emission with increasing copper concentrations.The present work indicates that the thermoluminescence response of these glasses to gamma rays can be reasonably measured in the range of 0.001-100 kGy.This study also facilitates the understanding of the basic TL mechanism in this glass system.

Study on Tribological Properties of Irradiated Crosslinking UHMWPE Nano-Composite

Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

Effects on Agronomic Traits of M_1 by Pollen of Upland Cotton Irradiated by ^(60)Co-γ Ray

[Objective] The aim was to provide reference for research on radiation and breeding of cotton pollen through irradiating common ripe pollen grain of upland cotton by 60Co-γ Ray of varied doses. [Method] Ripe pollen grains of upland cotton were irradiated by 60Co-γ Ray with doses of 5, 10, 15, and 20 Gy, respectively, to learn radiation effect and select appropriate dose. [Result] Most properties of M1 obviously showed variation when dose was over 10 Gy; vitality, growth, and fertility were greatly inhibited when dose was 15 Gy which was almost semi-lethal concentration, and variation species were richest at the same time, which provided materi- als for practical breeding. [Conclusion] 60Co-γ Ray of 15 Gy is more suitable for mutagenesis research on ripe pollen grains of upland cotton.

Fixation and Creep of Compressed Wood of Chinese Fir Irradiated with Gamma Rays

In order to discuss the mechanisms of permanent fixation of wood compression set , compressed wood of Chinese fir (Cunninghamia lanceolata) was irradiated by gamma rays from 60 Co. The irradiation doses were 0 (for match specim ens), 10 3, 5×10 3, 10 4, 5×10 4, 10 5, 5×10 5, 10 6, 5×10 6 Gy, res pectively. Then the weight loss, the equilibrium moisture content (EMC), the rec overy of wood compression set after adsorption (RSA) and the recovery after imme rsion in water (RSW), as well as the creep behaviour under a dry specimen condit ion and under an adsorption and subsequent desorption condition were measured an d discussed. This research proves that the doses of gamma irradiation have great effect on weight loss, EMC, RSA, RSW of irradiated compressed wood of Chinese f ir. The weight loss and the EMC increase, the RSA and the RSW fall drastically w hen the irradiation doses exceed 10 6 Gy. Both the instantaneous compliance and the creep compliance of the irradiated specimens under the two measurement cond itions show the general trend of increase with the increase of gamma irradiation doses. It can be deduced that decomposition or decrystallization reactions happ en in the wood cell wall at high gamma irradiation doses, especially at doses of around 5×10 6 Gy. In addition, this research proves that decomposition of mai n components of cell wall of compressed wood will lead to fixation of compressio n set of wood to a certain degree.

High-energy-density plasma in femtosecond-laser-irradiated nanowire-array targets for nuclear reactions

In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.

Preparation of Different Lights Irradiated ZnSe/GSH QDs and Their Interaction with BSA

Using L-glutathione(GSH) as a capping agent,Zn Se/GSH quantum dots(QDs) were prepared under microwave irradiation and irradiated under dark, ultraviolet light and incandescent light, respectively. The properties and interaction of different lights irradiated ZnSe/GSH QDs and bovine serum albumin(BSA) were studied systematically. The fluorescence(FL) spectra results reveal that the quenching mechanism are all the static quenching in nature. The quenching constant(Ksv) and binding constant(K) value of different irradiated Zn Se/GSH QDs and BSA all increased with the change of light types from dark to incandescent light and UV light. The number of binding site(n) is close to 1 at different temperatures. The lighting types influence the enthalpy and entropy changes. The Fourier transform infrared(FTIR) spectra indicate that the light induced GSH ligand will facilitate photocatalytic oxidation on the surface of ZnSe/GSH QDs. The circular dichroism(CD)results show that the α-helicity content of BSA decreases from 60.34%, 59.31%, to 58.79% under UV lighting,incandescent lighting and dark conditions. The interaction results of different lights illuminated ZnSe/GSH QDs with BSA by CD spectra method matches well with that by FL and FTIR spectra. That is, the interaction of ZnSe/GSH QDs and BSA from strong to weak is UV light, incandescent light and dark in sequence.

Hot-Carrier Effects on Total Dose Irradiated 65 nm n-Type Metal-Oxide-Semiconductor Field-Effect Transistors

The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.

Defects of laser-irradiated KDP crystals with different fluences studied by photoluminescence spectroscopy

Photoluminescence(PL)bands from potassium dihydrogen phosphate(KDP)crystals are studied by time-resolved PL spectroscopy.KDPcrystals irradiated at a laser fluence of 11.5 J/cm^(2) are found to have the highest probability of phosphorus–oxygen hole center defects and the lowest probability of phosphorus-oxygen electric center defects,in contrast to the probabilities of these defects forKDPcrystals irradiated at 9.0 J/cm^(2).The probabilities of these two defects occurring in retired components are found to be intermediate between those for crystals irradiated at the two different fluences.The two types of defects may result fromtwo differentmechanisms and may interconvert under certain conditions.Thus,there are differences between the defects in KDP crystals irradiated at a high laser fluence and those in retired components.

Ionoluminescence Spectra of a ZnO Single Crystal Irradiated with 2.5MeV H^＋ Ions

The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.

Free Volume Changes in γ-Irradiated Polyethylene and Polytetraflourethylene

Positron lifetime spectrum was measured and the change of the free volume was studied for commercial polyethylene (PE) and polytetrafluoroethylene (PTFE) during 7-irradiation processing up to 265 kGy. The free volume size increases but the crystallinity decreases as irradiation dose increases in PE. Both qualities (free volume size and crystallinity) in PTFE display an opposite behavior. The fractional free volume reduces monotonically with increasing irradiation dose in both PE and PTFE. The competition between the crosslinkmg and the splitting decomposition in polymers can be used to understand the free volume changes with irradiation dose.

Effect of Treatment Temperature on Iron Nitride Foils Irradiated with Nitrogen Plasma

We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ'-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.

Differentiation of Natural and Irradiated Blue Topaz by Cathodoluminescence(CL) Properties

Blue colored topaz is one of the most recognized gemstones worldwide.However,it is rarely found in the field and the products have been made mostly in laboratory using gamma,neutron and electron irradiation or combinations of these devices.Origin of the blue color in topaz remains not well understood, largely due to a lack of nondestructive way in idnetifying the blue topaz.Here we report a compari-

Thermoluminescence Responses of Photon and Electron Irradiated Ge- and Al-Doped SiO_(2) Optical Fibres

We carry out a comparison of the thermoluminescence (TL) response of photon and electron irradiated Ge- and Al-doped SiO_(2) optical fibres,as well as cross-comparison with that of TLD-100.Irradiation is made with 6 MeV electrons and 6 MV photons,for doses ranging from 0.2 Gy to 4.0Gy.The commercially available Al- and Gedoped optical fibres produce a linear dose-TL response.The TL yield for both of the doped fibres and also for TLD-100 is greater for electron irradiation than for photon irradiation.The TL yield of the Al-doped fibres is a small fraction of that of Ge-doped fibres (by a factor of 25),the Ge-doped fibres offering a response of 59%o of that of TLD-100.

Vacancy-Type Defects in Neutron-Irradiated Silicon

Position annihilation measurements show that the radiation defects and secondary defects in neutron-transmutation-doped(NTD)Si irradiated by two neutron doses can he removed at 600-650℃。The concentration and annealing behavior of V-type and Vo defects are related to the neutron doses.V_(4 )appears at 150℃ and 450℃-550℃ in NTD Si irradiated by higher neutron dose.

Orientation Dependence of Photoelectron Angular Distribution in Nitrogen Molecule Irradiated by XUV Laser Field

We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of local density approximation complemented by self-interaction correction. It is found that photoelectron emission in one photon regime could be considered as a probing tool for the main character of different types of molecular orbitals （σ or π）. The pattern of emitted photoelectrons strongly depends on the polarized angle of the laser, for σ orbital, the number of photoelectron decreases with increasing the polarized angle, while for π orbital, it has the inverse relation to the polarized angle, which reveals the multi-electron effect in molecules. On the other hand, concerning the total photoelectron emission, one should take into account a few occupied orbitals instead of only the outmost one.

The Magnetic Order in Ion Irradiated Graphite

The magnetism of highly oriented pyrolytic graphite （HOPG） induced by ion implantation is investigated with electron spin resonance （ESR） spectroscopy and magnetization measurements. The results indicate that the ESR spectra of the HOPG sample correlate with ion species, incident energy and dose of implantation. The correlation of the ESR spectra and magnetism of the HOPG sample with ：2C＋ ion implantation and H＋ ion implantation are studied in detail. The ferromagnetism of the HOPG sample is likely related to the asymmetric L1 line, which may be attributed to the interaction between localized defects and itinerant electrons occupied in the ＇impurity＇ band induced by ion implantation.

Toxicological Studies of Irradiated Pollen for Medicinal Use

The toxicity and mutagenicity of irradiated pollen were studied. Its oral LD50 value was＞21,500 mg/kg for both malc and female mice. Mutagenicity assays were studied by three short-term tests. Ames test showed that irradiated pollen did not induce any mutation of the strains TA97, TA98, TA100 and TA102. Micronucleus test on the bone marrow cells of mice showed no significant difference in the percentages of polychromatic erythrocytes with micronuclei between the exposed groups and the control. Chromosomal test on the reproduction cells of mice showed no change on the chromosomal aberration rate. These results demonstrate that irradiated pollen is safe for medicinal use.

Structural integrity evaluation of irradiated LEU targets for the production of molybdenum‑99 using thermo‑mechanical behavior simulation coupled with pressure of fission gas release calculation

Irradiated low-enriched uranium as target plates is used to produce,via neutron radiation and from the molybdenum-99 fission product,technetium-99m,which is a radio-element widely used for diagnosis in the field of nuclear medicine.The behavior of this type of target must be known to prevent eventual failures during radiation.The present study aims to assess,via prediction,the thermal–mechanical behavior,physical integrity,and geometric stability of targets under neutron radiation in a nuclear reactor.For this purpose,a numerical simulation using a three-dimensional finite element analysis model was performed to determine the thermal expansion and stress distribution in the target cladding.The neutronic calculation results,target material properties,and cooling parameters of the KAERI research group were used as inputs in our developed model.Thermally induced stress and deflection on the target were calculated using Ansys-Fluent codes,and the temperature profiles,as inputs of this calculation,were obtained from a CFD thermal–hydraulic model.The stress generated,induced by the pressure of fission gas release at the interface of the cladding target,was also estimated using the Redlich–Kwong equation of state.The results obtained using the bonded and unbonded target models considering the effect of the radiation heat combined with a fission gas release rate of approximately 3%show that the predicted thermal stress and deflection values satisfy the structural performance requirement and safety design.It can be presumed that the integrity of the target cladding is maintained under these conditions.