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Aging is characterized by a progressive deterioration in metabolic functions. The present study aimed to investigate the antagonistic effects of ginsenoside Rg1 (Rg1) on the γ-ray irradiation-induced aging of mixed hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). C57BL/6 mice were divided into a control group, a γ-ray irradiation group that served as an aging mouse model, and an Rg1 group. The Rg1 group was treated with Rg1 at dosage of 20 mg/kg/day for 7 days prior to γ-ray irradiation. The aging mouse model was established by exposing the mice to 6.5-Gy γ-ray total-body irradiation. Stem cell antigen 1 positive (Sca-1 + ) HSC/HPCs isolated from the mice were examined using a senescence-associated β-galactosidase (SA-β-Gal) staining assay. The cell cycle of the HSC/HPCs was examined using flow cytometry. A mixed hematopoietic progenitor cell colony-forming unit (CFU-mix) assay was also conducted. The mRNA and protein expression levels of sirtuin 1 (SIRT1), SIRT3, forkhead box O3 (FOXO3) and superoxide dismutase (SOD2) were evaluated using western blot and reverse transcription-quantitative PCR assays. The results indicated that Rg1 treatment significantly increased white blood cell, red blood cell and platelet counts in peripheral blood compared with those in the γ-ray irradiation group (P<0.05). However, Rg1 significantly attenuated the senescence of Sca-1 + HSC/HPCs in the γ-ray irradiation aging mice model. The proportion of SA-β-Gal stained HSC/HPCs was significantly decreased and CFU-Mix counts were significantly increased in the Rg1 group compared with the γ-ray irradiation group (P<0.05). Rg1 significantly increased the mRNA and protein levels of SIRT1, SIRT3, FOXO3 and SOD2 in the Sca-1 + HSC/HPCs compared with those in the γ-ray irradiation group (P<0.05). The percentage of Sca-1 + HSC/HPCs arrested at the G1 phase in the Rg1 group was significantly decreased compared with that in the γ-ray irradiation group (P<0.05). In conclusion, the present study indicates that Rg1 exerts anti-aging effects via the regulation of SIRT1-FOXO3 and SIRT3-SOD2 signaling pathways, and triggering the progression of Sca-1 + HSC/HPCs from the G1 phase to the S phase in γ-ray irradiation-induced aging mice., (Copyright: © Tang et al.)

The effect of γ-ray irradiation on the surface plasmon resonance (SPR) sensing capability of refractive index (n = 1.418–1.448) of the silica glass optical fiber comprised of germano-silicate glass cladding embedded with Au nano-particles (NPs) was investigated. As the γ-ray irradiation increased from 1 h to 3 h with the dose rate of 1190 Gy/h, the morphology of the Au NPs and the SPR spectrum were found to change. The average diameter of Au NPs increased with the aspect ratio from 1 to 2, and the nano-particles became grown to the clusters. The SPR band wavelength shifted towards a longer wavelength with the increase of total dose of γ-ray irradiation regardless of the corresponding refractive indices. The SPR sensitivities (wavelength/refractive index unit, nm/RIU) also increased from 407 nm/RIU to 3553 nm/RIU, 1483 nm/RIU, and 2335 nm/RIU after the γ-ray irradiation at a total dose of 1190 Gy, 2380 Gy, and 3570 Gy, respectively. [ABSTRACT FROM AUTHOR]

Abstract Intense investigations are in progress globally towards the immobilization of radioactive and non-radioactive nuclear waste by their direct vitrification or by using novel glassy materials as an alternate shield. In fact, the entire technologies and economies of nuclear waste immobilization have been envisaged in the future on the basis of these approaches. Use of the glassy materials for shielding purpose is an important step towards realizing this vision. The radiation-induced effects of γ-ray irradiation (60Co source, 4 kGy, 8kGy and 12 kGy doses) have been examined in a novel STS ChGA. The physicochemical properties of present STS ChGA have been compared before and after γ-ray irradiation. Analysis of the different properties reveals the non-linear and non-monotonic behavior with increase in the dose of γ-ray irradiation but it suggests the possibilities of the application of this novel material for radiation shielding. In view of practical application in nuclear waste immobilization, the present finding reveals the possibilities for development of innovative ChGA based shielding system with stable and controlled parameters (like thermal stability, glass forming ability, crystallization rate, hardness etc). An attempt has been also made for understanding the mechanisms of radiation-induced effects in the present study. [ABSTRACT FROM AUTHOR]

Intensive study on structure transformation of muscovite single crystal under high-dose γ -ray irradiation is essential for its use in irradiation detection and also beneficial for mechanism cognition on defect formation within a matrix of clay used in the disposal of high-level radioactive waste (HLRW). In this work, muscovite single crystal was irradiated with Co-60 γ ray in air at a dose rate of 54 Gy min -1 with doses of 0-1000 kGy. Then, structure transformation and mechanism were explored by Raman spectrum, Fourier-transform infrared spectrum, X-ray diffraction, thermogravimetric analysis, CA, scanning electron microscope and atomic force microscopy. The main results show that variations in the chemical/crystalline structure are dose-dependent. Low-dose irradiation sufficiently destroyed the structure, removing Si-OH, thus declining hydrophilicity. With dose increase up to 100 kGy, CA increased from 20° to 40°. Except for hydrophilicity variation, shrink occurred in the (004) lattice plane which later recovered; the variation range at 500 kGy irradiation was 0.5% close to 0.02 Å. The main mechanisms involved were framework break and H 2 O radiolysis. Framework break results in Si-OH removal and H 2 O radiolysis results in extra OH introduction. The extra introduced OH probably results in Si-OH bond regeneration, lattice plane shrink and recovered surface hydrophilicity. The importance of framework break and H 2 O radiolysis on structure transformation is dose-dependence. At low doses, framework break seems more important while at high doses H 2 O radiolysis is important. Generally, variations in the chemical structure and surface property are nonlinear and less at high doses. This indicates using the chemical structure or surface property variation to describe irradiation is correct at low doses but not at high doses. This finding is meaningful for realizing whether muscovite is suitable for detecting high-dose irradiation or not, and mechanism exploration is efficient for identifying the procedure for defect formation within the matrix of clay used in disposal HLRW in practice., Competing Interests: There are no conflicts to declare.

The radial structural heterogeneity of thermally-stabilized polyacrylonitrile (PAN) fiber is considered to be a limiting factor affecting the mechanical properties of the resulting carbon fibers. In this study, we demonstrate that a low-dose (60 kGy) γ-ray irradiation pretreatment can effectively mitigate the radial structural heterogeneity of PAN fibers after thermal stabilization. The characterization results indicate that low-dose γ-ray irradiation only affects the physical structure of PAN through decreasing its crystalline size and crystallinity, rather than inducing chemical cross-linking and/or intramolecular cyclization. It is proposed that an increased amorphous region in PAN fibers prompted by low-dose γ-ray irradiation can facilitate oxygen diffusion from skin to core during stabilization, which results in the increased structural homogeneity of stabilized PAN fibers. [ABSTRACT FROM AUTHOR]

In this paper, chitosan (CS)/graphene oxide (GO) composite films were prepared, and the effect of γ-ray irradiation on the properties of composite films was investigated. The irradiation crosslinking reaction occurred in composite films with the existence of acetic acid, and the properties changed upon the various irradiation dose. The swelling degree of the composite film with 0 wt % GO decreased with the increasing of the irradiation dose, but the swelling degree of which with GO increased instead. The thermal stability increased with the increasing of the irradiation dose, but the effect of the irradiation on the thermal stability weakened as the increasing of the content of GO, due to the enhanced irradiation resistance performance. The tensile strength increased firstly and decreased subsequently with the increasing of the irradiation dose and the content of GO. Composite films showed the enhanced antibacterial activity against Bacillus subtilis , compared to Escherichia coli and Staphylococcus aureus . The antibacterial activity weakened with the increasing of the content of GO. The antibacterial activity was relatively stronger when the irradiation dose was 20 KGy. In addition, the structural, crystal, and morphological properties of composite films were characterized by FT-IR, XRD, and SEM. It is worth noting that the GO was pre-functionalized via KH560 for the better compatibility with CS matrix., Competing Interests: The authors declare no conflict of interest.

60 Co γ-ray irradiation-initiated reversible addition⁻fragmentation chain transfer (RAFT) polymerization at room temperature with 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the chain transfer agent was first applied to acrylonitrile (AN) polymerization, providing a "green" platform for preparing polyacrylonitrile (PAN)-based carbon fibers using an environment-friendly energy source. Various effects of dose rate, molar ratio of the monomer to the chain transfer agent, monomer concentration and reaction time on the AN polymerization behaviors were performed to improve the controllability of molecular the weight and molecular weight distribution of the obtained PAN. The feature of the controlled polymerization was proven by the first-order kinetics, linear increase of the molecular weight with the monomer conversion and a successful chain-extension experiment. The molecular weight and molecular weight distribution of PAN were characterized by size exclusion chromatography (SEC). ¹H NMR and Matrix assisted laser desorption ionization/time of flight mass spectra (MALDI-TOF-MS) confirmed the chain-end functionality of PAN, which also was supported by the successful chain-extension experiments of original PANs with acrylonitrile and styrene as the second monomers respectively.

The photoluminescence and thermoluminescence characteristics of rare earths (Dy or Ce) activated LiCaBO3 phosphors have been studied. Phosphors were synthesized by modified solid state synthesis. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescence studies. Dy(3+) activated LiCaBO3 shows emission at 486 and 577 nm due to (4) F9/2 →(6) H15/2 and (4) F9/2 → (6) H13/2 transition, respectively, whereas the PL emission spectra of Ce(3+) activated LiCaBO3 phosphor shows a broad band peaking at 432 nm, which is due to the transition from 5d level to the ground state of the Ce(3+) ion. The thermoluminescence study was also carried out for both these phosphors for γ-ray irradiation and carbon beam irradiation. Linearity was studied for a 0.4-3.1 Rad dose γ-rays. Linear behaviour over this dose range was observed. Gamma ray-irradiated phosphors were shown to be negligible fading upon storage. All the samples were also studied for 75 MeV C(5+) ion beam exposure in the range of 3.75 × 10(12) - 7.5 × 10(13) ion cm(-2) fluence. In addition to this, trapping parameters of all the samples were also calculated using Chen's peak shape method., (Copyright © 2015 John Wiley & Sons, Ltd.)

Cycloparaphenylenes (CPPs) have attracted wide attention because of their interesting properties owing to distorted and strained aromatic systems and radially oriented p orbitals. For application of CPPs, information on their charged states (radical cation and radical anion) is essential. Here, we measured absorption spectra of the radical cations and the radical anions of CPPs with various ring sizes over a wide spectral region by means of radiation chemical methods. The peak position of the near-IR bands for both the radical cation and the radical anion shifted to lower energies with an increase in the ring size. This trend is contrary to what is observed for transitions between the HOMO and LUMO of the neutral CPP. The observed spectra of the CPP radical ions were reasonably assigned based on time-dependent density functional theory. These results indicate that the next HOMO and the next LUMO levels are important in the electronic transitions of radical ions.