[en] Dry seeds of Arabidopsis thaliana were irradiated with F ions and H ions with the energy range from keV to MeV, respectively. The inhibition of germination was investigated to display the influences of ion mass, energy and fluence. The results show that H ion irradiation is more effective in decreasing the germination rate than heavier F ion irradiation. After irradiation of F ions, a decrease-increase-decease type of germination rate-fluence response curve was found and the ion fluence at the peak position decreases with ion energy increase. The possible mechanism of above experimental results is discussed in this paper. (authors)

[en] The molecular dynamics method was used to simulate the conformation changes of the secondary structure of peptide molecules induced by MeV proton irradiation. The simulation results indicate that the sample's secondary structure was changed from α-helix to β-sheet gradually when the sample got energy higher than 3-5 eV from the incident ion, and the energy transfer mode has significant effect on final secondary structure of the sample. besides, the proton irradiation causes manifold final secondary structures compared with that caused by raising the sample temperature. (authors)

[en] The study on products of CT DNA irradiated with heavy ion is very important to understand the biologic effect induced by heavy ions. The authors have analyzed the products of CT DNA irradiated with MeV F ions using agarose gel electrophoresis, MALDI-TOF and HPLC methods. The results show that the products are mostly multi-DSB in our experiment observed by agarose gel electrophoresis, and there are not observable products between 1,000 and 30,000 (m/z) using MALDI-TOF method. HPLC result indicates some small biomolecules occurring in the products. These results suggest that the break of CT DNA induced by MeV heavy ions irradiation was not a random process. (authors)

[en] The water saturated Arabidopsis seeds were irradiated with protons in air. The ion energy is from 1.1 MeV to 6.5 MeV. According to TRIM simulation, the damaged region of the seed induced by the incident ions is near the surface region of the embryo, half of the embryo and the whole embryo, respectively. The protons with high energy can damage the shoot apical meristem (SAM) in the embryo while the protons with low energy cannot. The ion fluence used in this experiment was in the range of 4 x 10⁹ to 1 x 10¹⁴ ions/cm². The experimental results showed that both the germination and survival rates decrease while increasing ion fluence, and the fluence-response curve for different damaged region of the embryo has different characters. Besides SAM, which is generally considered as the main radiobiological target, the existence of a secondary target besides SAM is proposed in this paper. (authors)

[en] The dose-effect of the implantation of N⁺ and Ar⁺ on thymine and uracil were studied in this paper. Simulative curves were given when the sputtering of the intact sample molecules and the decomposition of the sample were taken into account. The simulative curves were fit for dose-effect curves when the sputtering and damage parameters change. It was also found that thymine and uracil had different sensitivities to N⁺ and Ar⁺. (authors)

[en] A study of the fragments of DNA irradiated with MeV ions is important for the understanding of the DNA damage mechanism and the subsequent biological effects (induced by heavy ions). In this experiment, the products of calf thymus DNA (CT DNA) irradiated with MeV fluorine ions were analyzed using agarose gel electrophoresis, modified time-of-flight mass spectrometer (MALDI-TOF), and high-performance liquid chromatography (HPLC). The results showed that the molecular mass of the fragments were concentrated around 831 bp with agarose gel electrophoresis, there was no observable product in the range of 1,000-30,000 (m/q) using MALDI-TOF, and small biomolecules were separated from the products. The results of this study indicated that the strand breaks of calf thymus DNA induced by MeV fluorine ions were nonrandom. (authors)

[en] Nitrogen doping can provide a large number of active sites for lithium-ion storage, thus can yield a higher capacity for lithium-ion batteries. However, most of the reported N-doped graphene-based materials have low nitrogen content (<10 wt%) as the introduction of nitrogen atoms prefer to be produced at edges and defects in the graphene lattices. Owing to the formation of edges and defects, the doped states or active sites can easily be located and nitrogen contents can be determined precisely. Here we present the preparation of N-doped graphene nanoribbons with high nitrogen contents (11.8 wt%) and a facile tunable configuration of doped states. The material can be used as an anode for lithium-ion batteries and shows a higher capacity (the electrode has a reversible capacity of 1100.34 mA h g⁻¹ at a charge/discharge rate of 100 mA g⁻¹, corresponds to a discharge time of about 9 h), better rate performance (the electrode has a reversible capacity of 471 mA h g⁻¹ at the current density of 2 A g⁻¹, corresponds to a discharge time of about 11.6 min) and improved cycling stability (87.37% of the initial capacity after 200 cycles). The experimental results and first-principle calculations suggest that the residual oxygen-containing functional groups of N-doped graphene nanoribbons promote the formation of pyrrolic nitrogen at edges and substantially increase the room for nitrogen doping. This work opens new strategies for designing and developing N-doped graphene anodes for high performance lithium-ion batteries. (paper)

[en] Surface properties of polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET) samples treated by microwave-induced argon plasma have been studied with contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanned electron microscopy (SEM). It is found that plasma treatment modified the surfaces both in composition and roughness. Modification of composition makes polymer surfaces tend to be highly hydrophilic, which mainly depended on the increase of ratio of oxygen-containing group as same as other papers reported. And this experiment further revealed that C=O bond is Key factor to the improvement of the hydrophilicity of polymer surfaces. Our SEM observation on PET shown that the roughness of the surface has also been improved in micron scale and it has influence on the surface hydrophilicity