Genetic Transformation of Watermelon with Pumpkin DNA by Low Energy Ion Beam-mediated Introduction

The No.601 watermelon (citrullus lanatus) seeds were treated with 25 keV N+ implantation at the dosage of 7.8 ×1016 ions/cm2. After treatment, watermelon seeds were incubated with 380μg/μl pumpkin (Cucubita, maxima Duch) DNA solution at 35 ℃ for 5 hours. By two-generations of selection and resistance screening at seedling stage, one transformed material was selected out, whose rind color is similar to that of the donor pumpkin and whose size of seeds is between that of the donor and the receptor. Using AFLP (amplified fragment length polymorphism) technique, two polymorphic DNA fragments were amplified. This primarily testified that the donor DNA fragments/gene were introduced into the receptor cell and integrated into the genomic DNA of the receptor.

Bioeffects of Low Energy Ion Beam Implantation:DNA Damage,Mutation and Gene Transter

Low-energy ion beam implantation （10 - 200 keV） has been proved to have a wide range of biological effects and is broadly used in the breeding of crops and micro-organisms.To understand its mechanisms better and facilitate its applications, the developments in the bioeffects of low energy ion beam implantation in the past twenty years are summarized in this paper.

Preliminary Studies on Base Substitutions and Repair of DNA Mismatch Damage Stimulated by Low Energy N^+ Ion Beam Implantation in Escherichia coli

Ever since the low energy N+ ion beam has been accepted that the mutation effects of ionizing radiation are attributed mainly to direct or indirect damage to DNA. Evidences based on naked DNA irradiation in support of a mutation spectrum appears to be consistent, but direct proof of such results in vivo are limited. Using mutS, dam and/or dcm defective Eschericha coli imitator strains, an preliminary experimental system on induction of in vivo mutation spectra of low energy N+ ion beam has been established in this study. It was observed that the mutation rates of rifampicin resistance induced by N+ implantation were quite high, ranging from 9.2 x 10~8 to 4.9× 10~5 at the dosage of 5.2×1014 ions/cm2. Strains all had more than 90-fold higher mutation rate than its spontaneous mutation rate determined by this method. It reveals that base substitutions involve in induction of mutation of low energy nitrogen ion beam implantation. The mutation rates of mutator strains were nearly 500-fold (GM2929), 400-fold (GM5864) and 6-fold larger than that of AB1157. The GM2929 and GM5864 both lose the ability of repair DNA mismatch damage by virtue of both dam and dcm pathways defective (GM2929) or failing to assemble the repair complex (GM5864) respectively. It may explain the both strains had a similar higher mutation rate than GM124 did. It indicated that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N+ implantation. The further related research were also discussed.

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.

Electron-beam radiation effects on the structure and properties of polypropylene at low dose rates

While the high-energy radiation effects on polypropylene, which are crucial for the cable industry for nuclear power plants, have been thoroughly studied, the property changes of PP at low-dose-rate electron-beam irradiation are far from elucidated. Herein, the influence of electron-beam irradiation on the structure and properties of PP was examined. The static EB irradiation conditions were 1.2 MeV at a low dose rate of 20 kGy/h to achieve absorbed doses ranging from 45, to 60, 100, and 200 kGy.The molecular structure was first evaluated by measuring the carboxyl index and the relative radical concentrations via Fourier transform infrared spectroscopy and electron spin resonance, respectively. Mechanical, differential scanning colorimetric, and rheological tests were carried out to further investigate the changes in the properties(tensile, crystalizing, and viscoelastic properties) of irradiated PP, which showed good agreement with the structural analysis results. We found that radio-oxidative degradation(chain scission) was predominant, which can be due to the low dose rate facilitating oxygen diffusion into the PP matrix during electron-beam irradiation.

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.

The feasibility and safety of high-intensity focused ultrasound combined with low-dose external beam radiotherapy as supplemental therapy for advanced prostate cancer following hormonal therapy

The aim of this study was to investigate the feasibility and safety of high-intensity focused ultrasound （HIFU） combined with （＋） low-dose external beam radiotherapy （LRT） as supplemental therapy for advanced prostate cancer （PCa） following hormonal therapy （HT）. Our definition of HIFU＋LRT refers to treating primary tumour lesions with HIFU in place of reduced field boost irradiation to the prostate, while retaining four-field box irradiation to the pelvis in conventional-dose external beam radiotherapy （CRT）. We performed a prospective, controlled and non-randomized study on 120 patients with advanced PCa after HT who received HIFU, CRT, HIFU＋LRT and HT alone, respectively. CT/MR imaging showed the primary tumours and pelvic lymph node metastases visibly shrank or even disappeared after HIFU ＋LRT treatment. There were significant differences among four groups with regard to overall survival （OS） and disease-specific survival （DSS） curves （P=0.018 and 0.015）. Further comparison between each pair of groups suggested that the long-term DSS of the H IFU ＋ LRT group was higher than those of the other three groups, but there was no significant difference between the HIFU＋LRT group and the CRT group. Multivariable Cox＇s proportional hazard model showed that both HIFU＋LRT and CRT were independently associated with DSS （P=0.001 and 0.035） and had protective effects with regard to the risk of death. Compared with CRT, HIFU ＋LRT significantly decreased incidences of radiation-related late gastrointestinal （GI） and genitourinary （GU） toxicity grade ≥ II. In conclusion, long-term survival of patients with advanced PCa benefited from strengthening local control of primary tumour and reRional lymph node metastases after HT. As an alternative to CRT, HIFU＋LRT showed Rood efficacy and better safety.

Mutation Breeding of an Organic Phosphorus-Solubilizing Bacterium B3 by Low Energy Ion Beam Implantation

A preliminary study on the mutation breeding of an organic phosphorus-solubilizing bacterium B3 by low-energy N^＋ ion beam was conducted. Analysis of dosage vs. survival rate and mutation rate showed that the dosage of 3×10^15 ions/cm^2 was optimal for the mutation. Some parameters for determining the efficient phosphorus content were studied to simplify the protocols for screening. Ultimately one reliable mutant was screened out under plating and flask-culturing screening conditions. Importantly, a novel phosphorus-dissolving mechanism is reported for the first time in terms of bio-surfactant production, which indicates that bio-surfactant might play a vital role in phosphorus-dissolving for some phosphobacteria.

Evidence for Base Substitutions and Repair of DNA Mismatch Damage Induced by Low Energy N^+ Ion Beam Implantation in E. coli

Ever since the low energy N + ion beam has been accepted, the mutations of ionizing radiation are attributable mainly to avoidance of DNA damages repair. Evidences based on in vivo proof results are limited. Using the E.coli wild type and mutator strains, the mutant frequencies suggest that base substitutions in rpoB gene are induced by the N + implantation. A highly conserved region is selected to get the direct evidence for base substitutions by sequence of the high fidelity PCR amplification products in mutants. Most of the mutants (90.9%, 40/44) have at least one base substitution in the amplification region. The evidences for CG to TA (55%, 22/40), AT to GC (20%, 8/40) and TA to CG (5%, 2/40) transitions are identified. The transversions are AT to TA (15%, 6/40) and GC to CG (5%, 2/40). It is suggested that DNA cytosine methylase might play an important role in mismatch repair of DNA damage induced by N + implantation by analysis of the mutant frequencies of mutator strains.

Low Velocity Impact Response Analysis of Shape Memory Alloy Reinforced Composite Beam

The low velocity impact responses of shape memory alloy （ SMA ） reinforced composite beams were analyzed by employing the finite element method. The finite element dynamic equntion was solved by the Newmark direct integration method, the impact contact force was determined asing the Hertzian contact law, and the influence of SMA .fibers on stiffiwss matrix is studied. Numerical results show that the SMA fibers can effectively improve the low velocity impact response property of composite beam.

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.

Beam Characteristics at Low Dose Monitor Unit Settings for Vero4DRT

The stability of delivery of low monitor unit (MU) setting is important especially for step-and-shoot intensity-modulated radiotherapy (IMRT), because the nature of the technique is inherent to repeat beam on/off according to the number of the segments. This study evaluates the dose linearity and profile flatness/symmetry under low MU settings for Vero4DRT, a new linear-accelerator based irradiation system that currently implements step-and-shoot IMRT. To evaluate the dose linearity and flatness/symmetry, the point doses and beam profiles were measured as functions of MU and dose rates. The accuracy of dose delivery depended on the dose rate. Under all dose rates, the dose was linear within 1% above 5 MU and within 2% above 3 MU. The beam symmetry was degraded in-line compared with crossline, although both profiles were symmetric within 2% at all dose settings. The profile flatness was also within 2% above 5 MU at any dose rate and showed no significant variation among the low MU settings. To ensure stable beam delivery without increasing the treatment time of Vero4DRT, we recommend a delivery of 5 MU per segment at a dose rate of 500 MU/min.

Slice-wise reconstruction for low-dose cone-beam CT using a deep residual convolutional neural network

Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.

A New Synthesis Method for Sum and Difference Beam Pattern with Low Sidelobe

A new method for sum and difference beam pattern synthesis with low sidelobe is proposed.In the situation of phase taper weighting,it makes use of Fourier transform pair relationship existing between the array factor and the element excitations and uses a loop iterative way to derive the array element excitations according to given array factor.The iteration does not stop until the array element excitations meet the initial sidelobe requirements.The method overcomes the defects of traditional methods,such as more searching times,larger amount of calculation and poor robustness.In addition,it can also synthesize the low sidelobe pattern in case of element failures.Simulation verifies the effectiveness of the method.

A Mutant of Bacillus Subtilis with High-Producing Surfactin by Ion Beam Implantation

In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope （SEM）. The optimum condition of ions implantation, 20 keV of energy and 2.6 × 10^15N^＋/cm^2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum （ESI/MS） and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain.

Low-alpha optics design for SSRF

In this paper,short pulse radiation in Shanghai Synchrotron Radiation Facility(SSRF)is generated by the low momentum compaction factor(α_C)optics,and three kinds of the low-α_C optics are found,with the very lowα_C being adopted by reducing dispersion in the straight section to negative value in the SSRF.Energy acceptance is selected as objective functions in nonlinear optimization rather than the second orderα_C or other nonlinear driving terms.The optimal result is improved step-by-step by randomly setting harmonic sextupole strengths.Two optics modes,i.e.low positiveα_C and low negativeα_C,are analyzed.In order to get a large energy acceptance and only one stable point in longitudinal phase space,the low negativeα_C optics is taken as an operation mode for the short pulse radiation in the SSRF.

Proteome Changes in Maize Embryo(Zea mays L)Induced by Ion Beam Implantation Treatment

Low energy ion beam implantation was applied to the maize （Zea mays L） embryo proteome using two-dimensional gel electrophoresis. Protein profile analysis detected more than Ii00 protein spots, 72 of which were determined to be expressed differently in the treated and control （not exposed to ion beam implantation） embryos. Of the 72 protein spots, 53 were up- regulated in the control and 19 were more abundantly expressed in the ion beam-treated embryos. The spots of up- or down-regulated proteins were identified by matrix assisted laser desorption /ionization-time of flight mass spectrometry （MALDI-TOF-MS）. Among the identified proteins, ii were up-regulated in the treated embryos. Four of these up-regulated proteins were antioxidant molecules, three were related to stress response, two to sugar metabolism and two were associated with heat shock response. Of the five proteins up-regulated in the control embryos, three were functionally related to carbohydrate metabolism; the functions of the remaining two proteins were unknown. The data collected during this study indicate that treatment of maize embryos with low energy ion beam implantation induces changes in stress tolerance enzymes/proteins, possibly as a result of alterations in metabolism.

Simple General Purpose Ion Beam Deceleration System Using a Single Electrode Lens

Ion beam deceleration properties of a newly developed low-energy ion beam implantation system were studied. The objective of this system was to produce general purpose low-energy (5 to 15 keV) implantations with high current beam of hundreds of μA level, providing the most wide implantation area possible and allowing continuously magnetic scanning of the beam over the sample(s). This paper describes the developed system installed in the high-current ion implanter at the Laboratory of Accelerators and Radiation Technologies of the Nuclear and Technological Cam-pus, Sacavém, Portugal (CTN).

Seismic Behaviour of Beam-Column Joints of Precast and Partial Steel Reinforced Concrete

A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is located in the core joint region and the connections between concrete members. This paper presents an experimental study of a series of PPSRC specimens. These specimens are tested under low cyclic loading.Experimental results demonstrate that the bearing capacity of the PPSRC specimens is 3 times that of the ordinary reinforced concrete( RC) beam-column joints. The strength and stiffness degradation rates are slower compared with that of the RC beam-column joints. In addition,the strength of the core joint region and the connections is higher than other parts of the PPSRC specimens. Beam failure occurs firstly for the PPSRC specimens,followed by column failure and connections failure. The failure of the core joint region occurs finally.Test results show that the seismic performance of the PPSRC is better than that of the ordinary RC beam-column joints.