Γ-ray Irradiation Research Articles

Gamma–ray irradiation of lead iodide precursor for enhanced perovskite crystalline properties

We describe an effective method for tuning the structure of lead iodide (PbI2) via high-energy gamma (γ)-ray irradiation. The chemistry of the precursor used in preparing the solution critically determines the quality of the perovskite films and the photovoltaic performance. We investigated the dependence of the precursor crystal structure and morphology on the γ-ray irradiation dose without by-products. The crystal orientation of PbI2 gradually changed when PbI2 was exposed to γ-ray radiation, causing it to form high-valent iodoplumbates with organic solvents because of the increase in the Pb oxidation number required to maintain a planar structure. The iodoplumbates suppress rapid crystallization and limit the space available for the grains to grow, thereby improving perovskite crystallinity. We also analyzed the optical and electrical properties of a perovskite film containing the irradiated precursor and compared them with those of a film containing the pristine PbI2 precursor. The detailed analysis of the crystal structure of the film revealed the effects of γ-ray irradiation. The PSC devices produced with γ-irradiated precursor material displayed improved performance. The direct treatment of precursors with high energy sources, such as γ-rays, which does not involve fabrication, is efficient in improving perovskite structures.

Influences of gamma-ray irradiation on PVDF membrane behavior: An experimental study based on simulation and numerical analysis

This study aims to explore the effects of gamma rays on various properties of poly(1,1-difluoroethylene) (PVDF) membranes under different irradiation conditions. The effects of 60Co γ-ray irradiation on the hydrophilicity, permeability, and mechanical performances of the PVDF membranes were discussed. Results showed that the size of the radiation dose rate had almost no effect on the performance of the membranes, as determined by the total radiation dose. The fracture and collapse of the PVDF structure under anaerobic conditions were obviously lower than those under aerobic conditions. Advanced characterization methods confirmed that the initial impact of gamma rays on the PVDF membranes occurred between 50 and 200 kGy. When the total dose exceeded 200 kGy, structural collapse and chain scission caused by the oxidative degradation mechanism became widespread, thereby leading to the relaxation of the PVDF network and the decline in properties. This study provides valuable information for the application of PVDF membranes to radioactive wastewater and clarifies the mechanism of membrane irradiation degradation to help prolong the service life of membranes. In addition, low total irradiation dose can embellish polymers and thus provide a feasible method for modifying and grafting polymer membranes in the future.

A novel approach for the reduction of aflatoxin in pistachio nuts using experimental and MCNP simulation

Humans are greatly affected by aflatoxin exposure via the dietary intake of pistachio nuts which pose a serious health risk. This study analysed the reduction of aflatoxin-B1 (AFB1) in pistachio using the exposure of gamma-rays of radioactive granite rock (RGR). The AFB1 level was measured using high-performance liquid chromatography (HPLC). Meanwhile, the reduction of AFB1 in pistachios was examined in two steps. In the first step, AFB1 reduction was examined via different masses of pistachio paste placed on the RGR bed which measured approximately 45% of AFB1 reduction. Whereas, 97% reduction in AFB1 was observed in pistachios within the small packets placed on the RGR bed. The second step was designed to investigate the effects of irradiation time and mass of RGR bed on the AFB1 reduction using RGR bed. Based on the results, the increase in AFB1 reduction level was recorded by increasing the γ-ray irradiation time and the mass of RGR. Through the introduction of the pistachio dosimetric AFB1 reduction coefficient (η), an empirical formula was developed to predict the amount of AFB1 reduction in the pistachio by RGR bed. Overall, the consistency level between empirical formulas and practical results is about 84–87%. Meanwhile, the gamma radiation was calculated using the Monte Carlo N Particle eXtended (MCNPX) simulation code. In conclusion, the proposed novel technique demonstrated RGR to be a suitable industrial substrate for safe and hygienic storage of pistachios.

Exploring the ensiling characteristics and bacterial community of red clover inoculated with the epiphytic bacteria from temperate gramineous grasses.

To explore the microbiological factors that cause the difference in silage fermentation characteristics between temperate gramineous (Italian ryegrass and oat) grass and legume forage. Through γ-ray irradiation sterilization and bacterial transplantation technology, the sterilized red clover was inoculated as follows: (i) aseptic water (STRC); (ii) epiphytic bacteria on red clover (RCRC); (iii) epiphytic bacteria on oat (RCOT); and (iv) epiphytic bacteria on Italian ryegrass (RCIR). Red clover was ensiled in laboratory-scale silos made of vacuum-packed plastic bags for 1, 3, 7, 14, 30 and 60days. STRC remained unfermented state based on similar chemical components with fresh red clover. Compared with RCRC and RCIR, higher lactic acid content and ratio of lactic acid to acetic acid, and lower pH, acetic acid and ammonia nitrogen contents were observed in RCOT after 60days of ensiling. Using next-generation sequencing, higher abundances of Methylobacterium and Sphingomonas were observed in the epiphytic bacteria on red clover. Pediococcus was dominant in RCRC after 3days of ensiling. Lactobacillus was the most predominant in each group after 60days of fermentation. RCRC and RCIR had a more hetero-fermentative process, while RCOT possessed a more homo-fermentative pathway. According to the 16S rRNA gene-predicted functional profiles, the metabolism of amino acids was accelerated by the epiphytic bacteria from red clover. Inoculating the epiphytic bacteria from oat could alter the fermentation characteristics and bacterial compositions of red clover silage. The relative abundance and activity of Methylobacterium, Sphingomonas, Enterobacteriaceae and hetero-fermentative Lactobacillus in red clover silage could be changed by the epiphytic bacteria on temperate gramineous grass. The exogenous micro-organisms inhibiting the metabolism of amino acids can be a good potential source to improve the silage quality of legume forage.

Gamma-ray irradiation effects on capacitance and conductance of graphene-based Schottky diode

The purpose of this study is to determine the effects of gamma (γ)-ray irradiation on capacitance and conductance features of Al/Graphene/Al2O3/p-Si structure. Graphene has been grown on copper foil by the Chemical Vapor Deposition (CVD) method and transferred onto Al2O3/p-Si by the wet transfer method. After Al/Graphene/Al2O3/p-Si structure has been exposed to 30 kGy and 60 kGy γ-ray irradiation, capacitance, and conductance measurements have been accomplished at 300 K. Electrical parameters have been compared before and after γ-ray irradiation for 50 kHz and 500 kHz. These results have been confirmed that capacitance and conductance values have increased after γ-ray irradiation and, have decreased when the radiation dose was increased from 30 kGy to 60 kGy. It has been observed that series resistance has decreased after 30 kGy radiation dose and has increased with increasing radiation dose.

Quantitative proteomic analysis of the effects of melatonin treatment for mice suffered from small intestinal damage induced by γ-ray radiation

Purpose Intestinal damage induced by radiation exposure is a major clinic concern of radiotherapy for patients with abdominal or pelvic tumor. Melatonin (N-acetyl-5-methoxytryptamine) is likely be an ideal radioprotector to protect individuals from radiation exposure. The study aimed to define the role of melatonin in small intestinal damage caused by abdominal irradiation (ABI). Materials and methods 30-day survival rate and pathological histology of the intestines from melatonin-treated mice after 13 Gy ABI exposure was first detected. Next, quantitative proteomics analysis of the small intestines tissue was examined and GO term and KEGG pathways analysis were performed. Results Melatonin treatment before ABI exposure significantly increased 30-day survival rate to 83% and ameliorated damage to the intestinal epithelial cells. Melatonin significantly altered the proteins profile of the small intestines following irradiation. For the irradiated mice treated with melatonin in comparison with the irradiated mice, the enriched GO terms were mainly involved in defense response to other organism (BP, GO: 0098542), response to other organism (BP, GO: 0051707), anion transmembrane transporter activity (MF, GO: 0008509), and secondary active transmembrane transporter activity (MF, GO: 0015291). In the process of antioxidant activity (MF, GO: 0016209), melatonin treatment prior to radiation exhibited high protein levels of Sod3 and Gpx3. The markedly KEGG pathways for melatonin treatment prior to radiation mainly included protein digestion and absorption (ko 04974) and mineral absorption (ko 04978). p53 signaling pathway and DNA repair pathways were enriched in melatonin treated mice. The amount of radiation-induced DNA damage and the cell apoptosis of the small intestines was decreased in the melatonin-treated mice. Conclusions Melatonin may protect small intestines from radiation damage through increasing DNA repair and decreasing cell apoptosis of the small intestines. Our data provided perspective for the study of melatonin in mitigating ABI-caused intestinal damage.

Improvement of cordycepin production by an isolated Paecilomyces hepiali mutant from combinatorial mutation breeding and medium screening.

Cordycepin is a major bioactive compound found in Cordyceps sinensis that exhibits a broad spectrum of biological activities. Here a Paecilomyces hepiali OR-1 strain was initially isolated from plateau soil for the bioproduction of cordycepin. Subsequently, strain modification including 60Co γ-ray and ultraviolet irradiation were employed to increase the cordycepin titer, resulted in a high-yield mutant strain P. hepiali ZJB18001 with the cordycepin content of 0.61mg/gDCW, showing a 2.3-fold to that from the wild strain (0.26mg/gDCW). Furthermore, medium screening based on Box-Behnken design and the response surface methodology facilitated the enhancement of cordycepin yield to the value of 0.96mg/gDCW at 25°C for 5days in submerged cultivation with an optimized medium composition. The high cordycepin yield, rapid growth rate and stable genetic characteristics of P. hepiali ZJB18001 are beneficial in terms of costs and time for the industrialization of cordycepin production.

Sponge-inspired reassembly of 3D hydrolyzed collagen aerogel with polyphenol-functionalization for ultra-capturing iodine from airborne effluents

The efficient capture of radioactive iodine (I-129, I-131) and radon (Rn-222) is crucial to the development of nuclear energy in spent fuel treatment. Herein, we successfully synthesized a new type of three-dimensional hydrolyzed collagen aerogel immobilized with catechin (Catechin@3DCF aerogel) as an effective adsorbent to remove iodine and radon through enzymatic hydrolysis, dialysis, freeze-drying, immobilization, and cross-linking. The as-prepared adsorbent was systematically characterized by FE-SEM, EDX, FT–IR, and XPS, showing that the adsorbent possesses ultra-high porosity, high content flake structure, and abundant adsorption sites on the surface of adsorbent. The results show that Catechin@3DCF aerogel exhibited excellent capture capacity for iodine and radon, with the maximum capture capacity of 222.67 wt% (88.5 wt% for 3DCF aerogel) and 44,877.9 Bq/Kg, respectively. Through the active group-shielding experiment analysis, the phenolic hydroxyl groups on the surface of adsorbent played a major role in iodine capture, followed by the -NHR group. In addition, mechanism studies have shown that the capture of iodine is mainly by chemical adsorption, while the capture of radon is mainly through physical adsorption, which is related to the numerous mesopores and flake structure of the adsorbent. Furthermore, Catechin@3DCF aerogel still maintains excellent adsorption capacity for iodine and radon under 60Co γ-ray irradiation at a total dose ranging from 10 to 350 kGy, indicating that it has excellent radiation resistance stability. Advantages such as novelty, ultra-high porosity, high-radiation stability, ultra-high capture capacity, environment-friendly, and low-cost indicate that biomass-derived Catechin@3DCF aerogel plays a role in the capture of radioactive iodine and radon from airborne effluents.

Hydrazine Radiolysis by Gamma-Ray in the N2H4-Cu+-HNO3 System.

Radiolysis of chemical agents occurs during the decontamination of nuclear power plants. The γ-ray irradiation tests of the N2H4–Cu+–HNO3 solution, a decontamination agent, were performed to investigate the effect of Cu+ ion and HNO3 on N2H4 decomposition using a Co-60 high-dose irradiator. After the irradiation, the residues of N2H4 decomposition were analyzed by Ultraviolet-visible (UV) spectroscopy. NH4+ ions generated from N2H4 radiolysis were analyzed by ion chromatography. Based on the results, the decomposition mechanism of N2H4 in the N2H4–Cu+–HNO3 solution under γ-ray irradiation condition was derived. Cu+ ions form Cu+N2H4 complexes with N2H4, and then N2H4 is decomposed into intermediates. H+ ions and H● radicals generated from the reaction between H+ ion and eaq− increased the N2H4 decomposition reaction. NO3− ions promoted the N2H4 decomposition by providing additional reaction paths: (1) the reaction between NO3− ions and N2H4●+, and (2) the reaction between NO● radical, which is the radiolysis product of NO3− ion, and N2H5+. Finally, the radiolytic decomposition mechanism of N2H4 obtained in the N2H4–Cu+–HNO3 was schematically suggested.

Protective behavior of tea catechins against DNA double strand breaks produced by radiations with different linear energy transfer

The number of DNA double strand breaks (DSBs) of genome-sized DNA was quantitatively evaluated under several types of radiation sources. The characteristics of radiation damages by different linear energy transfer (LET) and the effect of radiation protection by tea catechins were also studied as a function of its concentration. After β-rays and γ-rays irradiation to samples, the length of genome size DNA molecules (bacteriophage T4 GT7 DNA; 166 kbp) was measured by single molecule observation method using fluorescence microscope, which can estimate DSBs quantitatively. It was found that the number of DSBs was increased with increasing LET due to high radical density. By addition of EGCg ((-)-epigallocatechin gallate), the number of DSBs was reduced with a small concentration of 1 µM.

The effect of gamma and electron beam irradiation on the structural and physicochemical properties of myofibrillar protein and myosin from grass carp.

Myofibrillar protein (MPS) and myosin (MS) from grass carp was irradiated by γ-ray and electron beam (EB) irradiation with different dose (2, 4, 6, 8, and 10kGy). The changes in the physicochemical properties (solubility, Ca2+ -ATPase activity, total and reactive sulfhydryl content, surface hydrophobicity [S0 -ANS]), and structure of MPS and MS were investigated in the present work. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that there were degradation and aggregation of MPS and MS caused by irradiation, and the disappearance of myosin heavy chains (MHC) irradiated by EB was earlier than that of irradiated by γ-ray. As compared with MPS, the extracted MS was more easily destroyed. With the increase of irradiation dose, the particle size, solubility, Ca2+ -ATPase activity, and SH content of MPS and MS decreased (p<.05), while the S0 -ANS first increased and then decreased. Two-way analysis of variance results suggested that the degree of protein denaturation depends on the irradiation mode and dose. Compared with γ-ray irradiation, the EB irradiation had a greater impact on the physicochemical properties of MPS and MS.

Differences in the Fatty Acid Profile, Morphology, and Tetraacetylphytosphingosine-Forming Capability Between Wild-Type and Mutant Wickerhamomyces ciferrii.

One tetraacetylphytosphingosine (TAPS)-producing Wickerhamomyces ciferrii mutant was obtained by exposing wild-type W. ciferrii to γ-ray irradiation. The mutant named 736 produced up to 9.1 g/L of TAPS (218.7 mg-TAPS/g-DCW) during batch fermentation in comparison with 1.7 g/L of TAPS (52.2 mg-TAPS/g-DCW) for the wild type. The highest production, 17.7 g/L of TAPS (259.6 mg-TAPS/g-DCW), was obtained during fed-batch fermentation by mutant 736. Fatty acid (FA) analysis revealed an altered cellular FA profile of mutant 736: decrease in C16:0 and C16:1 FA levels, and increase in C18:1 and C18:2 FA levels. Although a significant change in the cellular FA profile was observed, scanning electron micrographs showed that morphology of wild-type and mutant 736 cells was similar. Genetic alteration analysis of eight TAPS biosynthesis-related genes revealed that there are no mutations in these genes in mutant 736; however, mRNA expression analysis indicated 30% higher mRNA expression of TCS10 among the eight genes in mutant 736 than that in the wild-type. Collectively, these results imply that the enhancement of TAPS biosynthesis in mutant 736 may be a consequence of system-level genetic and physiological alterations of a complicated metabolic network. Reverse metabolic engineering based on system-level omics analysis of mutant 736 can make the mutant more suitable for commercial production of TAPS.

Long-term multiband correlation study and spectral energy distribution modeling of blazar 3C 454.3

Abstract We analyzed the multiband and long-term light curves of blazar 3C 454.3 over a time span of more than 10 yr. The discrete correlation functions (DCFs) between the γ-rays (Fermi-LAT) and the U and V bands (Swift) show simultaneous variations above the 99% confidence level. The DCFs between the X-ray band and the ultraviolet/U bands (Swift-UVW2, Swift-UVW1) are correlated over the 95% confidence level, with the X-ray variations leading by 98 d. The observed X-ray emission might not come from the same region as the γ-rays. For the studied time range, we identify four flare states and one quiescent state in the γ-ray light curve. With a synchrotron self-Compton + external Compton (EC) model, the spectral energy distributions (SEDs) of the five quasi-simultaneous observed states are modeled to discuss the underlying reasons for the flares. The EC soft photons could originate from the broad-line region (BLR) rather than from the dusty torus for the quiescent and four activity states. This indicates that the γ-ray radiation area may be located inside the BLR. From the quiescent state to the flare states, the fitting results show that N0, γmax, γbr, and δ increase, while B and R decrease. The reproduction of the SEDs implies that the increase in the bulk Lorentz factor and the emitted electron power might be the primary reason for the γ-ray flares.

Effect of gamma and neutron irradiation on properties of boron nitride/epoxy resin composites

Improving the radiation resistance of epoxy resin (EP) is pivotal for the reliability of equipment and the safety of facilities in the nuclear industry. Hexagonal boron nitride (h-BN) is attractive in the preparation of radiation-resistant materials due to its good radiation stability and neutron shielding capability. In this work, h-BN/EP composites with enhanced radiation resistance were fabricated by solution blending. The tensile strength and thermal properties of the composites after γ-ray and neutron irradiation were investigated. The results showed that the addition of h-BN improved the mechanical property and the glassy transition temperature of the resin. The presence of low-level h-BN was favorable to enhance the radiation resistance of EP. As for composites with the 0.05% mass percentage of h-BN, the absorbed dose required to decrease relative tensile strength by 50% was about 300 kGy, which was higher than that of neat EP. The intrinsic mechanism of radiation resistance was attributed to the oxygen barrier effect as investigated by XPS and EPR. Then, benefiting from the absorbing neutrons capability of boron atoms, an addition of 0.55% h-BN to the EP resin could reduce the neutron transmittance of the resin by 5.6%. This study demonstrates that the blending with h-BN can increase the radiation-resistant property of EP resin, meanwhile augmenting the neutron shielding ability.

Polymer Film Blend of Polyvinyl Alcohol, Trichloroethylene and Cresol Red for Gamma Radiation Dosimetry.

This study investigated the polymer film composite of polyvinyl alcohol (PVA), trichlorethylene (TCE) and cresol red (CR) dye irradiated with gamma (γ) rays for potential application as radiation dosimetry. The film was prepared via the solvent-casting method with varying concentrations of TCE. Film samples were exposed to radiation from a γ-rays radiation source of 60Cobalt isotope. Color changes before and after γ-rays irradiation were observed, and the optical properties of the polymer films were investigated by spectrophotometry. Results show that increasing the radiation dose physically changed the color of the polymer film, from purple (pH > 8.8) without radiation (0 kGy) to yellow (almost transparent) (2.8 < pH < 7.2) at the highest dose (12 kGy). The concentration of acid formed due to irradiation increased with the increase in irradiation doses and at higher TCE content. The critical doses of PVA-TCE composites decreased linearly with the increase of TCE composition, facilitating an easy calibration process. The dose response at 438 nm increased exponentially with increasing radiation dose, but showed an opposite trend at the 575 nm band. An increase in the TCA concentration indicated a decrease in the absorption edge and an increase in activation energy, but both decreased for all TCE concentrations at higher doses. The energy gap for the direct and the indirect transitions decreased with increasing TCE concentration and γ-rays radiation dose. The results of this study demonstrated the potential application of PVA-TCE-CR polymer film as γ-rays irradiation dosimetry in a useful dose range of 0–12 kGy.

Effect of the GeO2 content on the radiation resistance of Er3+ -doped silica glasses and fibers

In this work, Er/Al/Ge co-doped silica glasses with different GeO2 content (0–3 mol%), as well as Ge/Al co-doped silica glasses, are prepared by combining the sol–gel and high-temperature sintering methods. Further, the effects of the GeO2 content on the absorptions and emissions properties, and lifetimes of the glasses before and after 1KGy γ-ray irradiation are compared. The Er/Al/Ge co-doped silica fibers are prepared from a preform produced via modified chemical vapor deposition (MCVD) combined with nano sol-doping. The effects of Ge co-doping on the optical loss and amplifier gain of the Er-doped silica fibers (EDFs) before and after irradiation are also investigated. The related mechanism and species of the γ-ray radiation-induced color centers are revealed via radiation-induced-absorption (RIA) and continuous wave electron paramagnetic resonance (CW-EPR) spectroscopies. The results revealed that co-doping with GeO2 considerably improves the radiation resistance of the glass and exerts a slight effect on the spectral properties of the Er/Al/Ge co-doped silica glasses before irradiation. The RIA and CW-EPR spectra revealed that the aluminum–oxygen hole center (AlOHC) defects reduce with increasing GeO2 content because the intermediaries, the Ge-related oxygen-deficient centers (GeODC(I) and GeODC(II)), exhibit stronger abilities to trap the holes compared with the [AlO4/2]− group. This reduces the RIA level in the visible and near-infrared regions of the Er/Al/Ge co-doped silica glass. The irradiation experiment on the fiber further confirmed that the radiation resistance of EDFs can be considerably improved by Ge co-doping.

Enhancement of T2* Weighted MRI Imaging Sensitivity of U87MG Glioblastoma Cells Using γ-Ray Irradiated Low Molecular Weight Hyaluronic Acid-Conjugated Iron Nanoparticles.

IntroductionIt has been reported that low-molecular-weight hyaluronic acid (LMWHA) exhibits a potentially beneficial effect on cancer therapy through targeting of CD44 receptors on tumor cell surfaces. However, its applicability towards tumor detection is still unclear. In this regard, LMWHA-conjugated iron (Fe3O4) nanoparticles (LMWHA-IONPs) were prepared in order to evaluate its application for enhancing the T2* weighted MRI imaging sensitivity for tumor detection.MethodsLMWHA and Fe3O4 NPs were produced using γ-ray irradiation and chemical co-precipitation methods, respectively. First, LMWHA-conjugated FITC was prepared to confirm the ability of LMWHA to target U87MG cells using fluorescence microscopy. The hydrodynamic size distribution and dispersion of the IONPs and prepared LMWHA-IONPs were analyzed using dynamic light scattering (DLS). In addition, cell viability assays were performed to examine the biocompatibility of LMWHA and LMWHA-IONPs toward U87MG human glioblastoma and NIH3T3 fibroblast cell lines. The ability of LMWHA-IONPs to target tumor cells was confirmed by detecting iron (Fe) ion content using the thiocyanate method. Finally, time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging and in vitro magnetic resonance imaging (MRI) were performed to confirm the contrast enhancement effect of LMWHA-IONPs.ResultsFlorescence analysis results showed that LMWHA-FITC successfully targeted the surfaces of both tested cell types. The ability of LMWHA to target U87MG cells was higher than for NIH3T3 cells. Cell viability experiments showed that the fabricated LMWHA-IONPs possessed good biocompatibility for both cell lines. After co-culturing test cells with the LMWHA-IONPs, detected Fe ion content in the U87MG cells was much higher than that of the NIH3T3 cells in both thiocyanate assays and TOF-SIMs images. Finally, the addition of LMWHA-IONPs to the U87MG cells resulted in an obvious improvement in T2* weighted MR image contrast compared to control NIH3T3 cells.DiscussionOverall, the present results suggest that LMWHA-IONPs fabricated in this study provide an effective MRI contrast agent for improving the diagnosis of early stage glioblastoma in MRI examinations.

Carbon nitride/positive carbon black anchoring PtNPs assembled by γ-rays as ORR catalyst with excellent stability

Electrocatalytic performance of low-cost graphitic carbon nitride (CN) is greatly limited by its limited conductivity and small specific surface area. Herein, a simple and cost-effective idea to produce novel nanocomposite is constructed by the CN and cetyl trimethyl ammonium bromide functionalized carbon black (CB) anchored platinum nanoparticles as highly efficient oxygen reduction catalysts based on gamma irradiation. The assembled carbon nitride/positive carbon black anchoring PtNPs (Pt/CN2-CB+ 1) catalyst exhibits significantly improved specific surface area, high graphitization, and uniformly dispersed ultra-small platinum nanoparticles. For the oxygen reduction reaction (ORR) performance, the catalyst shows more positive onset-potential (0.93 V versus RHE) and larger diffusion limiting current density (5.65 mA cm−2) compared with benchmark Pt/C catalysts in alkaline medium. Moreover, the Pt/CN2-CB+ 1 catalyst exhibits a small Tafel slope (92 mV dec−1). Besides, the catalyst was demonstrated the remarkable methanol tolerance and good long-term stability under working conditions. This work provides a new and effective γ-rays irradiation for synthesizing the carbon nitride catalysts for energy conversion and storage applications.

Influences of γ-ray irradiation on physico-chemical, structural, X-ray diffraction, thermal and antimicrobial activity of some γ-irradiated N′,N′′′-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide) metal complexes

A series of Co(II), Ni(II), Cu(II), Th(IV) and UO2(II) complexes have been synthesized from reaction of nitrogen based ligand (L) i.e. N′,N′′′-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide)(L) with their salts. Investigation of synthesized metal complexes was achieved by using elemental analyses, magnetic moment, molar conductance, FT-IR, UV/Vis. spectroscopy, thermal techniques and 3D molecular modeling. An octahedral geometry has been suggested for all complexes except for Ni(II) complex (2) which adopted tetrahedral geometry. To through a light on the probability of structure changes with γ-irradiation, the effect of gamma irradiation on powder samples of the complexes [Co(L)Cl2].4H2O (1); [Ni2(L)(OAc)4].5H2O (2) and [Cu(L)Br2].5H2O (3) was investigated after being exposed to high energetic γ-rays at 100 kGy dose (hereafter referred to as (1A,2A,3A, respectively). Spectral, thermal, magnetic susceptibility, molar conductance and powder X-ray diffraction patterns (XRD) were performed before and after irradiation. In addition, the in vitro antimicrobial activity of the complexes against Staphylococcus aureus as Gram-positive strain, Escherichia coli as Gram-negative strain and antifungal Candida albicans was performed for both unirradiated and irradiated samples. The obtained results showed that the irradiated complexes were affected, but not greatly by the applied γ-irradiation dose.

Tightly-bound trion and bandgap engineering via γ-ray irradiation in the monolayer transition metal dichalcogenide WSe2

After γ-ray irradiation treatment, a monolayer tungsten diselenide could be transitioned into an n-doped semiconductor due to the anion vacancies created by the radiation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interface. Change in the lattice vibrational modes induced by passivation of oxygen is captured by Raman spectroscopy. The frequency shifts in both in-plane and out-of-plane modes are dependent linearly on the oxidation content. We observe a negative trion, which is a neutral exciton bound with an electron, in the photoluminescence spectra. The binding energy of this trion is estimated to be ∼90 meV, making it a tightly bound exciton. The first-principles calculation suggests that an increase in the anion vacancy population is generally accompanied by a transition from a direct gap material to an indirect one. This opens up a new venue to engineer the electronic properties of transition metal dichalcogenides by using irradiation.