60Co Γ-ray Irradiation Research Articles

Inhaled amifostine for the prevention of radiation-induced lung injury

ObjectiveTo alleviate radiation-induced lung injury and prevent the related pneumonitis and pulmonary fibrosis by inhaled amifostine (AMI). Methods15 ​Gy 60Co γ-ray irradiation was performed on the thoracic area of rats once to establish the radiation injury model. AMI was intraperitoneally (i.p.) injected or intratracheally (i.t.) administered to the rats 30 ​min pre-irradiation. The protective effects of the two AMI administration manners were compared in the aspects of hematopoietic system, lung edema, and histopathological examination, and the mechanisms were explored. ResultsCompared to i.p. AMI, i.t. AMI remarkably alleviated radiation-induced lung injury and prevented consequent pneumonitis or pulmonary fibrosis. Specifically, i.t. AMI notably protected white blood cells and platelets, reduced the lung wet/dry weight ratio, and decreased collagen volume fractions compared to the model group (P ​< ​0.05), while i.p. AMI showed no significant difference with the model group (P ​> ​0.05). The high therapeutic efficiency of i.t. AMI was related to its high antioxidation and anti-inflammation effects with downregulation of pro-inflammatory cytokines, the enhanced superoxide dismutase activity, the low levels of malondialdehyde and total proteins. ConclusionInhaled AMI is a promising medicine for preventing radiation-induced lung injury, including pneumonitis and pulmonary fibrosis.

Characterization of a Novel Creeping Tartary Buckwheat (Fagopyrum tataricum) Mutant lazy1.

Gravity is known as an important environmental factor involved in the regulation of plant architecture. To identify genes related to the gravitropism of Tartary buckwheat, a creeping line was obtained and designated as lazy1 from the mutant bank by 60Co-γ ray radiation. Genetic analysis indicated that the creeping phenotype of lazy1 was attributed to a single recessive locus. As revealed by the horizontal and inverted suspension tests, lazy1 was completely lacking in shoot negative gravitropism. The creeping growth of lazy1 occurred at the early seedling stage, which could not be recovered by exogenous heteroauxin, hormodin, α-rhodofix, or gibberellin. Different from the well-organized and equivalent cell elongation of wild type (WT), lazy1 exhibited dilated, distorted, and abnormally arranged cells in the bending stem. However, no statistical difference of indole-3-acetic acid (IAA) levels was found between the far- and near-ground bending sides in lazy1, which suggests that the asymmetric cell elongation of lazy1 was not induced by auxin gradient. Whereas, lazy1 showed up-expressed gibberellin-regulated genes by quantitative real-time PCR (qRT-PCR) as well as significantly higher levels of gibberellin, suggesting that gibberellin might be partly involved in the regulation of creeping growth in lazy1. RNA sequencing (RNA-seq) identified a number of differentially expressed genes (DEGs) related to gravitropism at stages I (before bending), II (bending), and III (after bending) between WT and lazy1. Venn diagram indicated that only Pectate lyase 5 was down-expressed at stages I [Log2 fold change (Log2FC): −3.20], II (Log2FC: −4.97), and III (Log2FC: −1.23) in lazy1, compared with WT. Gene sequencing revealed that a fragment deletion occurred in the coding region of Pectate lyase 5, which induced the destruction of a pbH domain in Pectate lyase 5 of lazy1. qRT-PCR indicated that Pectate lyase 5 was extremely down-expressed in lazy1 at stage II (0.02-fold of WT). Meanwhile, lazy1 showed the affected expression of lignin- and cellulose-related genes and cumulatively abnormal levels of pectin, lignin, and cellulose. These results demonstrate the possibility that Pectate lyase 5 functions as the key gene that could mediate primary cell wall metabolism and get involved in the asymmetric cell elongation regulation of lazy1.

Total ionizing dose effect on 2-D array data transfer ICs designed and fabricated by 0.18 μm CMOS technology

Circuits for CMOS two-dimensional (2-D) array data transfer are indispensable for applications such as space and nuclear fields. Issues include being operated with higher speed, lower power, fewer size penalties, and radiation hardness. To meet these requirements, two kinds of CMOS 2-D array data transfer circuits, such as a shift register type and a memory access type, are proposed and fabricated by the standard 0.18 μm CMOS process technology. In both types, 16 μm pitch, 8 × 128 array data transfer operations were realized with a data rate of more than 1 Gb/s. Furthermore, we conducted 60Co γ-ray irradiation experiments on those circuits. The current consumption ratio of the shift register type to the memory access type ranges from 150 to 200% as the dosage increases. The result indicates that the memory access type has better radiation hardness at 1 Gb/s than that of the shift register type.

High energy irradiation effects on silicon photonic passive devices.

In this work, the radiation responses of silicon photonic passive devices built in silicon-on-insulator (SOI) technology are investigated through high energy neutron and 60Co γ-ray irradiation. The wavelengths of both micro-ring resonators (MRRs) and Mach-Zehnder interferometers (MZIs) exhibit blue shifts after high-energy neutron irradiation to a fluence of 1×1012 n/cm2; the blue shift is smaller in MZI devices than in MRRs due to different waveguide widths. Devices with SiO2 upper cladding layer show strong tolerance to irradiation. Neutron irradiation leads to slight changes in the crystal symmetry in the Si cores of the optical devices and accelerated oxidization for devices without SiO2 cladding. A 2-µm top cladding of SiO2 layer significantly improves the radiation tolerance of these passive photonic devices.

Co60 γ-ray irradiation on the structural and morphological properties of CoZnF NPs and their major applications

The Co1-xZnxFe2O4 (0.2 ≤ x ≤ 0.8) spinel ferrite nanoparticles (CoZnF NPs) were successfully prepared by sol-gel auto-combustion method using citric acid as a complexent performing important role to drive the chemical reaction. The pH of the solution was kept to 7 with an addition of ammonia solution (NH4OH) solution in order to maintain the stability in the solution. Single phase; cubic spinel structure of CoZnF NPs; space group Fd3m-1 was confirmed through obtained XRD pattern. A mean crystallite size (t), lattice parameter (ɑ) and other structural and morphological parameters before and after gamma irradiation were studied to show the effect of Co60 γ-irradiation with a total gamma dose of 5 Mrad on the physico-chemical properties of the material. The topography of the CoZnF NPs was analysed using the AFM images. The Raman spectroscopic analysis have shown the particular active modes Eg, 3T2g, and A1g. The UV–Vis spectroscopic absorption of CoZnF NPs was reported at ∼ 254.09 to ∼ 258.73 Å and the optical bandgap was found with the help of Tauc’s plot; Kubelka-Munk function F(R); that was reported to be 3.51–3.96 eV.

Radiation Triggered Phenotypic Changes of Regulatory T Cells

Ionizing radiation disrupts the immune balance easily. Regulatory T (Treg) cells directly affect the immune balance after radiation exposure. Meanwhile, the present study is to investigate the survival ability and phenotypic changes of Treg cells induced by 60Co γ-rays in order to expand the understanding on how Treg cells modulated by radiation. Mice lymphocytes were isolated from thymus and spleen at 1, 4 and 10 days after 2 Gy 60Co γ-rays irradiation. The proliferation and phenotype of Treg cells were analyzed by flow cytometry. Helio+ Treg cells were calculated and ATP luminescence was measured by ELISA. CD39 from thymus and spleen was measured by flow cytometry. Moreover, miR-31 expression in the thymus and spleen post irradiation was determined by RT-PCR. The apoptosis rate of Treg cells was increased to 13.1% in thymus and 44.2% in the spleen after 2Gy irradiation. The proliferation of Treg cells in thymus decreased from 31.6 to 14.2% post irradiation (t = 3.56, 5.72, P<0.05). The percentage of Helio+ Treg cells increased and the mean florescence intensity of Helio in Treg cells increased from 5,677.7 to 6,529 in thymus and increased from 3,968.7 to 4,558.7 in spleen. The ratio of CD39+ Treg in thymus was significantly increase from 43.2 to 83.8 after 10 days radiation (t = -18.29, P<0.05). ATP released by Treg cells was down-regulated after radiation (0.15 μmol/L, t = 31.98, p<0.05). Furthermore, miR-31 expression in CD4+T cells significantly decreased after 2 Gy radiation in the thymus. This study indicating the relationship between radiation induced Treg cell apoptosis and phenotype changes in vivo and provided a theoretical basis for the prevention and treatment of radiation-induced immune imbalance. Our study offered a new idea for radiotherapy combined with immunotherapy by target-regulating CD39 and miR-31.

Inhaled curcumin mesoporous polydopamine nanoparticles against radiation pneumonitis

Radiation therapy is an effective method to kill cancer cells and shrink tumors using high-energy X-ray or γ-ray. Radiation pneumonitis (RP) is one of the most serious complications of radiation therapy for thoracic cancers, commonly leading to serious respiratory distress and poor prognosis. Here, we prepared curcumin-loaded mesoporous polydopamine nanoparticles (CMPN) for prevention and treatment of RP by pulmonary delivery. Mesoporous polydopamine nanoparticles (MPDA) were successfully synthesized with an emulsion-induced interface polymerization method and curcumin was loaded in MPDA via π‒π stacking and hydrogen bonding interaction. MPDA owned the uniform spherical morphology with numerous mesopores that disappeared after loading curcumin. More than 80% curcumin released from CMPN in 6 h and mesopores recovered. CMPN remarkably protected BEAS-2B cells from γ-ray radiation injury by inhibiting apoptosis. RP rat models were established after a single dose of 15 Gy 60Co γ-ray radiation was performed on the chest area. Effective therapy of RP was achieved by intratracheal administration of CMPN due to free radical scavenging and anti-oxidation ability, and reduced proinflammatory cytokines, high superoxide dismutase, decreased malondialdehyde, and alleviated lung tissue damages were observed. Inhaled CMPN paves a new avenue for the treatment of RP.

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.

60Coγ-ray irradiation inhibits germination of fresh walnuts by modulating respiratory metabolism and reducing energy status during storage

Postharvest germination negatively affects the development of fresh walnut industry. Our previous research showed that 60Coγ-ray irradiation with 0.3 kGy effectively inhibited the germination of fresh walnuts during storage, but the underlying mechanism in respiratory metabolism remains still unclear. The untreated and 0.3 kGy-irradiated fresh walnuts were stored at 25 °C for 24 d, and then the indicators related to respiratory metabolism in kernels and embryos were determined. The results found that the 0.3 kGy irradiation decreased the respiration intensity after 15d and completely inhibited the germination of fresh walnuts with the declined adenosine triphosphate (ATP) content and energy charge (EC) levels in kernels except from 12 to 15 d and polyphenol oxidase (PPO), cytochrome C oxidase (CCO) and ascorbic acid oxidase (AAO) activities in both tissues except the stimulated PPO activity in embryos during storage. Moreover, the irradiation promoted the glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activities but reduced the isocitrate lyase (ICL) activity in both tissues, and decreased the nicotinamide adenine dinucleotide reduced form (NADH) content but increased the nicotinamide adenine dinucleotide phosphate reduced form (NADPH) content in kernels of fresh walnuts during storage. The irradiation induced the JRG6PDH and JR6PGDH expression levels in both tissues, as well as the JRICL and JRMS expression levels in kernels before 12 d but suppressed those after 12 d of storage. In conclusion, the germination inhibition of fresh walnuts by gamma irradiation is attributed to suppressed terminal oxidases activities, decreased ratio of Embden–Meyerhof–Parnas pathway-tricarboxylic acid cycle (EMP-TCA) and glyoxylate cycle (GAC), increased level of pentose phosphate pathway (PPP) and reduced energy status.

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.

SEBS effect on 60Co radiation resistance behavior of PP/HDPE matrix for medical device applications

Radiation resistant polypropylene (PP) has become more and more critical in the medical industry. Composites of PP were synthesized by melting process in the presence of high-density polyethylene (HDPE) and styrene–ethylene–butylene–styrene triblock copolymer (SEBS). Under 60Co γ-ray irradiation, all samples were characterized by mechanical properties, thermal analysis, contact angle (CA), FT-IR analysis, and SEM. Under a 20 kG y dose irradiation, mechanical properties results show that the impact strength rose from 3.28 kJ/m2 to 4.40 kJ/m2, and the tensile strength decreased by 3.52 MPa. At the same time, CA's results show that a much higher irradiation dose makes CA lower, but the higher content of SEBS, the higher CA. To confirm the presence of polar oxygen-containing groups, the FT-IR was used, and the results show that the characteristic peak intensity of carbonyl groups decreased gradually. SEM images indicate that the number of cracks and plastic particles reduced gradually, and the radiation resistance of samples enhanced by the aromatic ring structure of SEBS.

Total ionizing dose effects of 60Co-γ ray radiation on the resistive switching and its bending performance of Al-in-O/InOx-based flexible RRAM device

Flexible resistive switching random access memory (RRAM) device is one of the promising candidates for non-volatile memory used in space because of its features such as simple structure, high speed, low power consumption, durability and lightweight with reduction in thickness. Al-In-O/InOx self-mixing layer can be applied for flexible RRAM due to its low annealing temperature (i.e. temperatures<180 °C), forming-free resistive switching characteristics and low SET and RESET voltage. Herein, effects of the total ionizing dose of 60Co-γ ray radiation on the resistive switching, the bending performance of the prepared flexible RRAM devices based on the Al-In-O/InOx films were studied. The results indicated that the resistance decreases with the bias in high resistance state (HRS) and the SET voltages of the device decrease very slightly after irradiation, while the low resistance state (LRS), RESET voltage, and retention parameters are almost immune to radiation. Moreover, after irradiation, the decrease of resistance with the bias in HRS becomes more exacerbated when bended. Mechanism of bending on the RS is studied by the first-principles calculation, and the mechanism underlying the irradiation effect is studied from the viewpoint of the origin of RS.

Estimating the Relative Biological Effectiveness of Auger Electron Emitter 123I in Human Lymphocytes

Auger electron emitters are considered to be a promising strategy for targeted radionuclide therapy of metastatic diseases, given their high linear energy transfer (LET) and short range in tissue which could potentially limit normal tissue toxicity. Particularly, Auger electron emitters that can be targeted into the DNA of tumor cells have been considered as an attractive cancer therapy in the past decade. In this study, the efficiency of induction of chromosomal damage by Auger electron emitter 123I (half-life 13.2 hours) was investigated by using the cytokinesis-block micronucleus assay. A stannylated deoxyuridine was synthesized and radiolabeled with 123I, resulting in 123IUdR that carried the Auger electron emitter across the nuclear membrane and allowed its incorporation into newly synthesized DNA. The DNA damage caused by the 123I Auger cascade was estimated by evaluating the induced micronuclei frequencies in human peripheral blood lymphocytes obtained from three different donors. The isolated lymphocytes were stimulated with phytohaemagglutinin (1 mg/mL) for 48 hours before pulse labelling with 123IUdR and the S-phase fraction was determined using flow cytometry. Geant4 Monte Carlo calculations were performed to determine the absorbed dose in cells by the Auger emitter. The relative biological effectiveness (RBE) was calculated by comparing the dose response curves for 123IUdR with the reference dose response curves, obtained by 60Co γ-ray irradiation, for lymphocytes of the same donors. This resulted in a range of individual RBE values from 3 up to 10, depending on the donor and the radiation dose. In addition, dose limiting RBE values (RBEMax) were calculated for each donor and ranged from 5 to 11, dependent on the inherent radiosensitivity of the donors. This study provides valuable information on the RBE of Auger electron emitter 123I, which is identified as a promising theranostic radionuclide for future targeted radionuclide therapy.

Regulatory Effect of Angelica sinensis Polysaccharide on Bcl-2/Bax/Caspase-3 Signal Pathway in Spleen of Rats with Radiation Injury

To investigate the protective effect of Angelica sinensis polysaccharide (ASP) on spleen injury and its influence of Bcl-2/Bax/Caspase-3 signal pathway in radiation rats, 60 Sprague Dawley (SD) rats were divided into 5 groups randomly: the normal group, the model group, low-, middle- and high- dose of ASP groups. On the 15th day after the appropriate medication, all the rats except the normal group received the 60Co γ-ray irradiation once with a total dose of 4.0Gy. The levels of NF-kBp65 and IKKa in serum, the contents of MDA, GSH and SOD in spleen of each group were detected with ELISA after 24 h of irradiation, and the protein expression levels of Bcl-2, Bax, Caspase-3, HSPBP1 and TIMM8B in spleen of each group were detected by western blotting. The results showed that compared with the model group, NF-kBp65, IKKa and MDA contents were decreased while GSH and SOD contents were increased in the middle and high dose groups. The level of Bcl-2 and TIMM8B were increased while Bax, caspase-3 and HSPBP1 were decreased in all groups. In conclusion, Angelica sinensis polysaccharide can reduce the expression levels of Bax and caspase-3, while increase the level of Bcl-2 in spleen of rats induced by radiation and antagonize the body injury caused by radiation by regulating Bcl 2/Bax/Caspase 3 signaling pathway.

In-situ fabrication of porous-silica-microsphere-supported platinum nanocluster catalyst by γ-ray radiation

The synthesis and stable loading of metal nanoclusters have always been a hot and difficult topic in the field of nano-metal catalysts. In this work, micron-sized inverse opal SiO2 microspheres (IO-SiO2) are firstly prepared as the carrier of platinum nanoclusters (PtNCs) through a sol-gel process of tetraethyl orthosilicate (TEOS) on sacrificed polystyrene (PS) colloidal crystal microspheres template. After the IO-SiO2 carriers are dispersed into the aqueous solution of H2PtCl6 and irradiated by 60Co γ-ray radiation for a certain absorbed dose in a deoxygenized atmosphere, PtNCs with a size of less than 2 nm are in situ synthesized based on a redox equilibrium of Pt(0)/Pt(IV) induced by effect of the reductive species (eaq−, H) and oxidizing radicals (HO) produced by the radiolysis of water, and immobilized on IO-SiO2 without the help of any stabilizer. Due to the large pore volume of the IO-SiO2, the loading capacity of PtNCs can reach as high as 18.63 μg/mgmicrosphere. The prepared IO-SiO2-supported PtNCs (PtNCs@IO-SiO2) show excellent catalytic activity and recyclability for the reduction of o-nitroaniline by NaBH4 as the model reaction. This work offers a new route to prepare stable and high-performance metal nanocluster catalysts loaded on porous microspheres using γ-ray radiation technique.

Total ionization dose effects of N-type tunnel field effect transistor (TFET) with ultra-shallow pocket junction

N-type tunnel field effect transistors (TFETs) with Si1−xGex/Si hetero-junction in the ultra-shallow N+ pocket region have been fabricated. This paper investigates the total ionization dose (TID) effects on the electrical characteristics of these N-type TFET devices, including transfer and output characteristics, via a 60Co γ-ray irradiation source. TID has little impact on the on-state current for TFETs with and without P well. With the increase in total dose, however, a shift in the transfer characteristics, such as the off-state current and subthreshold slope is observed. Under the same TID condition, TFETs with P well exhibit more robustness as compared to TFETs without P well. The characteristics under room temperature and high temperature annealing conditions after irradiation are also investigated. The underlying mechanisms, such as the interplay among bulk trapped charge in gate oxide-induced inversion and interface trap-induced trap-assisted-tunneling, are identified by TCAD simulation and are discussed in detail.

A Model for Estimating Dose-Rate Effects on Cell-Killing of Human Melanoma after Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is a type of radiation therapy for eradicating tumor cells through a 10B(n,α)7Li reaction in the presence of 10B in cancer cells. When delivering a high absorbed dose to cancer cells using BNCT, both the timeline of 10B concentrations and the relative long dose-delivery time compared to photon therapy must be considered. Changes in radiosensitivity during such a long dose-delivery time can reduce the probability of tumor control; however, such changes have not yet been evaluated. Here, we propose an improved integrated microdosimetric-kinetic model that accounts for changes in microdosimetric quantities and dose rates depending on the 10B concentration and investigate the cell recovery (dose-rate effects) of melanoma during BNCT irradiation. The integrated microdosimetric–kinetic model used in this study considers both sub-lethal damage repair and changes in microdosimetric quantities during irradiation. The model, coupled with the Monte Carlo track structure simulation code of the Particle and Heavy Ion Transport code System, shows good agreement with in vitro experimental data for acute exposure to 60Co γ-rays, thermal neutrons, and BNCT with 10B concentrations of 10 ppm. This indicates that microdosimetric quantities are important parameters for predicting dose-response curves for cell survival under BNCT irradiations. Furthermore, the model estimation at the endpoint of the mean activation dose exhibits a reduced impact of cell recovery during BNCT irradiations with high linear energy transfer (LET) compared to 60Co γ-rays irradiation with low LET. Throughout this study, we discuss the advantages of BNCT for enhancing the killing of cancer cells with a reduced dose-rate dependency. If the neutron spectrum and the timelines for drug and dose delivery are provided, the present model will make it possible to predict radiosensitivity for more realistic dose-delivery schemes in BNCT irradiations.

High performance hydrogen/oxygen terminated CVD single crystal diamond radiation detector

We report the performance of a single crystal diamond radiation detector with gold films on hydrogen-terminated diamond as electrical contacts and oxygen-terminated diamond as surface isolation between electrodes. The origin-symmetric current-voltage characteristics showed excellent Ohmic contact behavior. An extremely low dark current value of 7.46 × 10−13 A/mm2 was measured at an electric field of 1 V/μm. The charge collection efficiency and energy resolution of this detector were 99.01% and 1.5% for holes, and 98.6% and 1.7% for electrons under irradiation with 241Am α-particles. Under 60Co γ-ray irradiation with a dose rate of 1.271 Gy/s, the gain factor, specific sensitivities, and signal-to-noise ratio were 49.46, 12.43 μC/Gy·mm3, and 1 × 106 at 200 V bias voltage (0.66 V/μm), respectively. A rise time of 347.4 ps of the response to a pico-second pulsed electron source was also measured. This research provides a possibility to improve the performance of the diamond radiation detector through diamond surface modification.

Radiation-Induced Structural Changes of Miscanthus Biomass

Efficient pretreatment is a prerequisite for lignocellulosic biomass biorefinery due to the structure of lignocellulose. This study is a first-time investigation into the structural changes of Miscanthus biomass treated with 60Co γ-ray irradiation in different doses up to 1200 kGy. The structural properties of the treated sample have been systematically characterized by FTIR, thermogravimetric analysis (TGA), XRD, gel permeation chromatography (GPC), a laser particle size analyzer, SEM, an atomic force microscope (AFM), and NMR. The results show that irradiation treatment can partially destroy the intra- or inter-molecular hydrogen bonds of biomass. Irradiation treatment can also reduce particle size, narrow the distribution range, as well as increase the specific surface area of biomasses. Noticeably, the TGA stability of the treated biomass decreases with increasing absorbed doses. To respond to these structural changes, the treated biomass can be easily hydrolyzed by cellulases with a high yield of reducing sugars (557.58 mg/g biomass), much higher than that of the untreated sample. We conclude that irradiation treatment can damage biomass structure, a promising strategy for biomass biorefinery in the future.