Impact of Low-Energy Ion Beam Implantation on the Expression of Ty1-copia-like Retrotransposons in Wheat(Triticum aestivum)

Retrotransposon-like elements are major constituents of most eukaryotic genomes. For example, they account for roughly 90% of the wheat （Triticum aestivum） genome, Previous study on a wheat strain treated by low-energy N^＋ ions indicated the variations in AFLP （Amplified Fragment Length Polymorphism ） markers, One such variation was caused by the re-activation of Tyl-copia-like retrotransposons, implying that the mutagenic effects of lowenergy ions might work through elevated activation of retrotransposons, In this paper an expression profile of Tyl-copia-like retrotransposons in wheat treated by low-energy N^＋ ions is reported, The reverse transcriptase （RT） domains of these retrotransposons were amplified by reverse-transcriptional polymerase chain reaction （RT-PCR） and sequentially cloned, 42 and 65 clones were obtained from the treated （CL） and control materials （CK）, respectively, Sequence analysis of each clone was performed by software. Phylogeny and classification were calculated responding to the sequences of the RT domains. All the results show that there is much difference in the RT domain between the control sample and the treated sample, Especially, the RT domains from the treated group encode significantly more functional ORF （open reading frames） than those from the control sample, This observation suggests that the treated sample has higher activation of retrotransposons, possibly as a consequence of low-energy ion beam irradiation, It also suggests that retrotransposons in the two groups impact the host gene expression in two different ways and carry out different functions in wheat cells.

Mutagenic Effects of BM302:GO112 Induced by Low-Energy Ion Beam Implantation

Mutant strains of GO112 and BM302 with a high 2-keto-L-gulonic acid （2KLG） transformation rate induced by ion beam implantation were separately and combinatorially compared with the original strains GO29 and BM80 to study the mutagenic effects of ion beam implantation. Both the sole GOl12 and mixed BM302：GOl12 demonstrated improved SNDH activity and 2KLG yield compared to the original strains. The mutant combinations of BM302：GOl12 showed a longer stationary phase and higher biomass than BM80：GO29. The mutant BM302 exhibited a stronger capacity to maintain a stable pH environment at mixed fermentation with Gluconobacter oxydans （G. oxydans） for 2KLG transformation and facilitated the growth of G. oxydans compared with the original strain BM80. The promotive capacity to L-sorbosone dehydrogenase （L-SNDH） from the supernate of BM302 was 1.6-fold higher than that of BM80. Genes encoded SNDH in GO29 and GOl12 were amplified and sequenced, and mutations including three transitions （CG →TA, CG →TA, GC → AT） and one transversion （AT→ TA） were confirmed from GO29 to GOl12. The corresponding amino acid was changed as Leu →Phe, Arg → Gln and Asn → Lys.

Analysis of a Partial Male-Sterile Mutant of Arabidopsis thaliana Isolated from a Low-Energy Argon Ion Beam Mutagenized Pool

A screen for Arabidopsis fertility mutants, mutagenized by low-energy argon ion beam, yielded two partial male-sterile mutants tc243-1 and tc243-2 which have similar phenotypes. tc243-2 was investigated in detail. The segregation ratio of the mutant phenotypes in the M2 pools suggested that mutation behaved as single Mendelian recessive mutations, tc243 showed a series of mutant phenotypes, among which partial male-sterile was its striking mutant characteristic. Phenotype analysis indicates that there are four factors leading to male sterility, a. Floral organs normally develop inside the closed bud, but the anther filaments do not elongate sufficiently to position the locules above the stigma at anthesis, b. The anther locules do not dehisce at the time of flower opening （although limited dehiscence occurs later）, c. Pollens of mutant plants develop into several types of pollens at the trinucleated stage. as determined by staining with DAPI （4＇,6-diamidino-2-phenylindole）. which shows a variable size. shape and number of nucleus. d. The viability of pollens is lower than that of the wild type on the germination test in vivo and vitro.

Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance.In this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation doses.The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)irradiation.Significant J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film devices.Clear Shapiro steps are observed under 10 GHz microwave irradiation.The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

A segmented conical electric lens for optimization of the beam spot of the low-energy muon facility at PSI: a Geant4 simulation analysis

The low-energy muon facility at PSI provides nearly fully polarized positive muons with tunable energies in the ke V range to carry out muon spin rotation(LE-μSR)experiments with nanometer depth resolution on thin films,heterostructures, and near-surface regions. The low-energy muon beam is focused and transported to the sample by electrostatic lenses. In order to achieve a minimum beam spot size at the sample position and to enable the steering of the beam in the horizontal and vertical direction, a special electrostatic device has been implemented close to the sample position. It consists of a cylinder at ground potential followed by four conically shaped electrodes,which can be operated at different electric potential. In LE-μSR experiments, an electric field at the sample along the beam direction can be applied to accelerate/decelerate muons to different energies(0.5–30 keV). Additionally, a horizontal or vertical magnetic field can be superimposed for transverse or longitudinal field μSR experiments. The focusing properties of the conical lens in the presence of these additional electric and magnetic fields have been investigated and optimized by Geant4 simulations. Some experimental tests were also performed and show that the simulation well describes the experimental setup.

Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.

Isothermal hydrogen absorption process of Pd-capped Mg films traced by ion beam techniques and optical methods

Pd-capped nanocrystalline Mg films were prepared by electron beam evaporation and hydrogenated under isothermal conditions to inves-tigate the hydrogen absorption process via ion beam techniques and in situ optical methods.Films were characterized by different techniques such as X-ray diffraction(XRD)and scanning electron microscopy(SEM).Rutherford backscattering spectrometry(RBS)and elastic recoil detection analysis(ERDA)provided a detailed compositional depth profile of the films during hydrogenation.Gas-solid reaction kinetics theory applied to ERDA data revealed a H absorption mechanism controlled by H diffusion.This rate-limiting step was also confirmed by XRD measurements.The diffusion coefficient(D)was also determined via RBS and ERDA,with a value of(1.1±0.1)·10^(−13)cm^(2)/s at 140℃.Results confirm the validity of IBA to monitor the hydrogenation process and to extract the control mechanism of the process.The H kinetic information given by optical methods is strongly influenced by the optical absorption of the magnesium layer,revealing that thinner films are needed to extract further and reliable information from that technique.

Half-integer Shapiro steps in MgB_(2) focused He ion beam Josephson junctions

Half-integer microwave induced steps(Shapiro steps)have been observed in many different Josephson junction systems,which have attracted a lot of attention because they signify the deviation of current phase relation(CPR)and uncover many unconventional physical properties.In this article,we first report the discovery of half-integer Shapiro steps in MgB_(2)focused He ion beam(He-FIB)Josephson junctions.The half-integer steps'dependence on microwave frequency,temperature,microwave power,and magnetic field is also analyzed.We find that the existence of half-integer steps can be controlled by the magnetic field periodically,which is similar to that of high temperature superconductor(HTS)grain boundary junctions,and the similarity of the microstructures between gain boundary junctions and He-FIB junctions is discussed.As a consequence,we mainly attribute the physical origin of half-integer steps in MgB_(2)He-FIB junctions to the model that a He-FIB junction is analogous to a parallel junctions'array.Our results show that He-FIB technology is a promising platform for researching CPR in junctions made of different superconductors.

Measuring and Analyzing Transverse Low-Energy Ion Beam Emittances

The transverse emittance of an ion beam describes its transverse size as the particles are transported from a source to a target.It allows for predicting beam losses in limiting apertures and the beam focus size at the target.Various definitions and issues are discussed.The most common and emerging measuring techniques are presented,including their advantages.Several methods of emittance data analysis,their accuracy and trustworthiness,are discussed.

Research on the Distant Hybrids of Wheat Obtained via Low-Energy Ion-Beam Implantation

The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu 5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plants obtained whose protein content was higher than 18.5 %, the highest one was 21.44 %. There were 3 plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically. The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.

Screening of Biocontrol Strain Bacillus subtilis by N^+ Ion Beam Implantation

[Objective] This study was to investigate the effect of N＋ ion beam implantation on the survival rate and mutation rate of biocontrol strain Bacillus subtilis. [Method] The factors influencing B. subtilis ion beam implantation, including culture time, dilution concentration, solvent, drying time of mycoderm were optimized. B. subtilis cells were implanted by using ion beam at dose of 2.0×10^14～4.0×10^14 ions/cm2 and the energy of 30 kev. Then the methods of culturing colonies confronting each other on plate and Oxford cup diffusion were used to screening strains. [Result] The optimal parameters were found as follows： culture in liquid for 20-24 h, dilution with sterile water to 106 cells/ml and drying time of 60 min for sample preparation; the optimal N＋ ion beam implantation dose of 2.0×10^14～4.0×10^14 ions/cm2 at the energy of 30 kev, the survival rate of 8.43%-26.71% and the mutation rate of 3.50%-5.43%. [Conclusion] This study provided reference for ion beam implantation mutation of B. subtilis.

Preliminary Study on the Low Energy Ion Beam Mediated Parameters with Fractional Factorial Design Method

[Objective] The aim was to explore the biological effect of low energy ion beam mediated parameters with fractional factorial design method. [Method] The twin-embryos seed of autotetraploid rice DER10-04-01 was taken as the receptor material,and the Elymus dahuricus Turcz. was used as materials to provide DNA to carry out the ion beam mediated experiment. And the fractional factorial design method was used to study the parameters of low enery N＋ ion beam mediated foreign genes into rice. [Result] The implantation energy,dose,DNA concentrations and immersion time of DNA showed significant biological effects on the normal growth and development of DER10-04-01,in which the biological effects of implantation dose and DNA concentrations were relatively obvious. [Conclusion] The implantation energy,dose,DNA concentrations and immersion time of DNA were major factors showing important effects on the experimental result in ion beam mediated foreign genetic materials.

High-Power and High-Efficiency 650nm-Band AlGaInP Visible Laser Diodes Fabricated by Ion Beam Etching

High power and high-slope efficiency 650nm band real-refractive-index ridge w aveguide AlGaInP laser diodes with compressive strained MQW active layer are for med by pure Ar ion beam etching process.Symmetric laser mesas with high perpendi cularity,which are impossible to obtain by traditional wet etching method due to the use of a 15°-misoriented substrate,are obtained by this dry etching metho d.Laser diodes with 4μm wide,600μm long and 10%/90% coat are fabricated.Th e typical threshold current of these devices is 46mA at room temperature,and a s table fundamental-mode operation over 40mW is obtained.Very high slope efficien cy of 1.4W/A at 10mW and 1.1W/A at 40mW are realized.

Gene Chip Analysis for Rice MicroRNA Response to Low Energy N^+ Beam Radiation

[Objective] The aim of this study was to explore the expression differences of miRNA response to low energy N＋ beam radiation in rice.[Method]Three groups of ion beam irradiation rice seeds and untreated rice seeds were selected respectively,and then the total RNA of seedlings after 96 h of germination was extracted at 30 ℃.Agilent gene chip was used to screen the differentially expressed genes of two groups of rice seedlings.The chip contained 510 miRNA probes;and about two times of expression differences between two samples were considered as the threshold range.[Result]14 miRNA molecules showed significant expression differences between the irradiated group and the control group,and all of them were decreased.[Conclusion]The miRNAs showed expression differences between irradiated group and the control group,which might regulate the expression of certain genes to respond to ion irradiation,thus producing physiological,biochemical and phenotypic differences.

Characterization of Ga NAs/ Ga As and Ga In NAs/ Ga As Quantum Wells Grown by Plasma-Assisted Molecular Beam Epitaxy: Effects of Ion Damage

The effects of ion damage on Ga NAs/Ga As and Ga In NAs/Ga As quantum wells ( QWs) grown by plas- ma- assisted molecular beam epitaxy have been investigated. Itis found thation damage is a key factor affecting the quality of Ga NAs and Ga In NAs QWs. Obvious appearance of pendello¨ sung fringes in X- ray diffraction pattern and remarkable im provement in the optical properties of the samples grown with ion removal magnets are observed.By removing nitrogen ions,the PL intensity of the Ga In NAs QW is improved so as to be comparable with that of Ga In As QW. The stronger is the magnetic field,the m ore obvious the PL intensity im provement would be.

Effects of Heavy-ion Beams Irradiation on Survival Rate and Antioxidant Enzymes of Sweet Sorghum Seedlings

[Objective] This study aimed to investigate the effects of heavy-ion beams irradiation on the seed germination potential, survival rate, antioxidant enzyme activi- ties and lipid peroxidation of sweet sorghum. [Method] The dry seeds were irradiated by ＇2（36. heavy ion beams with absorbed doses： 0, 40, 80, 120, 160 and 200 Gy, respectively. Then, the seed germination potential, survival rate, antioxidant enzyme activities and lipid peroxidation of sweet sorghum were measured. [Result] Heavy-ion beams irradiation exhibited different influence on germination potential and survival rates. Germination rate showed a downward trend, but the corresponding survival curve of seedlings was saddle-shaped. The activities of SOD, POD, CAT and ASA- POD changed in different trends as well. The MDA content rose toward increasing irradiation dose, suggesting that high dose of heavy-ion beams irradiation enhanced the damage to membrane of sweet sorghum seedlings. [Conclusion] After being irra- diated, germination potential and survival rates of sweet sorghum were decreased, and antioxidant enzymes activity changed greatly. This study laid the basis for fur- ther work on breeding and improvement of sweet sorghum irradiated by ,^（12）C^（6＋） heavy ion beams.

Quantitative Traits of Ion Beam Induced Mutagenesis in Triticum aestivum

[Objective] The aim of this study was to elucidate the quantitative traits of plants mutagenized by ion beam. [Method] The particular variation phenotypes, a- gronomic traits, and protein and wet gluten contents of progenies derived from the same ion beam induced mutant were investigated. [Result] Morphological polymor- phism existed in some individuals. Plant height, spike length and protein content were significantly influenced by ion beam, and effective tiller number and wet gluten content were moderately influenced. Multiple comparisons of all the indices within groups indicated genomic instability among these groups. Coefficient of variation im- plied the differences within group were very low. [Conclusion] Ion beam irradiation displayed characteristics of multi-directivity and non-directiveness. It aroused multiple variations in the same mutant. Instability among progeny indicates cells had different fate even in the same irradiated tissue. It may take several generations for mutants to stabilize particular phenotypes. The effects of ion beam irradiation may be the in- terrelated direct irradiation damage, indirect irradiation damage and late effect, such as bystander effect and adaptive response.

Cu_2ZnSnS_4 thin films prepared by sulfurization of ion beam sputtered precursor and their electrical and optical properties

Cu2ZnSnS4 (CZTS) thin films were successfully prepared by sulfurization of ion bean sputtered precursors on soda-lime glass substrate. The single phase of stannite-type structure CZTS films were obtained as revealed in EDS and XRD analysis when the ratios of the constituents of CZTS thin films are close to stoichiometric by optimizing the conditions of precursor preparation and sulfurization. A low sheet resistivity as about 0.156 Ω·cm and a high absorption coefficient as 1×104 cm-1 were achieved in this method by Hall effect measurements and UV-VIS spectrophotometer. The optical band-gap energy of the CZTS sample is about 1.51 eV, which is very close to the optimum value for a solar-cell absorber.

Purification and Properties of a New L-Sorbose Dehydrogenase Accelerative Protein from Bacillus megaterium Bred by Ion-Beam Implantation

Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein （SAP） to accelerate the activity of L-sorbose dehydrogenase （SDH） of Gluconobacter oxydans in the 2-keto-L-gulonic acid （2KLG） fermentation from L-sorbose by the mixed culture of B. megaterium BM302 and G. oxydans. The SAP purified by three chromatographic steps gave 35-fold purification with a yield of 13% and a specific activity of 5.21 units/mg protein. The molecular weight of the purified SAP was about 58 kDa. The SDH accelerative activity of SAP at pH 7 and 50℃ was the highest. Additionally, it retained 60% activity at a pH range of 6.5 ～ 10 and was stable at 20℃ ～ 60℃. After 0.32-unit SAP was added to the single cultured G. oxydans strains, the SDH activity was apparently accelerated and the 2KLG yield of GO29, GO112, GO and GI13 was enhanced 2.1, 3.3, 3.5 and 2.9 folds respectively over that of the strains without the addition of SAP.

Storage Stability in Reversion Mutation of a Rice Line Devoid of LOX-1, 2 Acquired by Ion Beam Irradiation

The effect of absence of lipoxygenase isoenzyme （LOX） on storage stability was investigated. Rice mutant 1297 without lipoxygenase isoenzyme-1 （LOX-1） or lipoxygenase isoenzyme-2 （LOX-2） generated by ion beam irradiation from Wanjian2090 and reversion mutant RM1297 with LOX-1 and LOX-2 were subjected to an accelerated-aging experiment. Shanyou63 （with LOX-1 and LOX-2 ） served as control. Results showed that the germination and dehydrogenase activity decreased while the electrical conductivity and free fatty acid content increased in all varieties with accelerated aging. In 1297 that lacked LOX-1 and 2, there were slight changes in germination, dehydrogenase activity, membrane permeability and free fatty acid content during the thirty-day accelerated-aging experiment. But in varieties with LOX-1 and LOX-2, significant changes were observed, suggesting that LOX-1, 2 might be a definite factor which influenced seed lifespan. This study also indicates that ion beam irradiation may be used as mutagen to generate mutant and reversion mutants for biological study and could become a new direction in ion beam application.