To optimize the protocols of the conservation for Chinese cherry (Prunus pseudocerasus Lindl.), in vitro-grown shoot tips of 'Taishanganying' were used as the material and an orthogonal test and single factor test were designed. The result showed that the optimal step of vitrification cryopreservation was: 50 days in vitro plantlets were cold hardened at 4 degrees C for 3 weeks. The shoot tips were peeled and precultured in 0.3 mol L-1 sucrose concentrations preculture medium for 1 day. Then they were treated with loading solution (LS) for 20 min before exposure to PVS3 at 0 degrees C for 90 min and plunged directly in liquid nitrogen (LN) where they were kept for at least 2 h. After thawing in 42 degrees C, 1 min, they were washed twice with DS. Two weeks after regrowth, the survival rate was 87.8%. Regenerated plants showed the same morphological characteristics as the control. It is proved to be viable and could be used for long-term storage of this species.

Shandong Province (SD) is the largest area of sweet cherry production in China. It also holds the dominant position in terms of nursery stock exports to the rest of the country. Several surveys on viral infections of sweet cherry in this district have been carried out. The rate of infection with Prunus necrotic ringspot virus (PNRSV), which causes serious economic losses in most Prunus species, is higher than that with other viruses in SD. The rate of PNRSV infection increased from 38.00% in 2011 to 66.67% in 2016. To better understand the genetic variation in PNRSV at a molecular level, 33 full-length PNRSV coat protein (CP) sequences from 23 PNRSV-infected samples were acquired. Compared with other PNRSV isolates obtained from GenBank, CP sequences from SD isolates shared 96.67-100 and 96.70-100% nucleotide sequence and amino acid sequence identity, respectively. Phylogenetic reconstruction confirmed the clustering of the isolates into three molecular groups (PV-96, PV-32, and PE-5), whereby SD isolates were separated into two phylogroups (PV-96 and PV-32). However, 10 of 23 samples exhibited mixed infection with PV-96-type and PV-32-type PNRSV. In mixed-infection samples, PV-96-type PNRSV (66.28%) was more likely to be detected than PV-32-type PNRSV (33.72%); and PV-96-type PNRSV (2.22%) was more likely to be mutated than PV-32-type PNRSV (1.65%). Furthermore, those mutations were often concentrated at specific positions. Therefore, analysis of nucleotide sequence 'hot spots' can provide information on the molecular mechanisms of viral mutagenesis.

The WRKY transcription factors are widely involved in the physiological processes related to plant growth and development as well as response to biotic and abiotic stresses. A full-length cDNA for PcWRKY3 (GenBank accession number KY399984) gene was cloned from the cherry (Prunus) rootstock 'Gisela 6' (Prunus cerasus x Prunus canescens) using reverse transcription-polymerase chain reaction (RT-PCR). The PcWRKY3 gene was found to contain an open reading frame (ORF) with 1,551 bp encoding 516 amino acids. Sequence analysis indicated that the resultant PcWRKY3 protein comprised of two conserved WRKY domains and two zinc finger structures (C2H2), and thus, belonged to Group I of the WRKY family. Furthermore, the expression of PcWRKY3 on treating the plantlets with 200 mmol mannitol and 200 mmol NaCl was analysed by quantitative RT-PCR. The gene exhibited differential expression under these artificial abiotic stresses, which suggested its potential role in the plant's response to abiotic stress factors. This study provides a basis for further analysis of the physiological functions of PcWRKY3 in environmental tolerance in cherry rootstocks.

This paper describes the ion beam irradiation facility built up at the 4 MV electrostatic accelerator of Shanghai Institute of Applied Physics (SINAP), CAS for simulating neutron damage to thorium molten salt reactor (TMSR) material studies. The system mainly consists of a beam line containing the magnetic scanning device and the beam monitoring device, and the high temperature high vacuum chamber. H+, He+, Ar+ions(<4 MeV, 2 μA) from the accelerator are used for ion beam irradiation. The range of irradiation temperature is from the liquid nitrogen temperature to 950 ℃. The maximum irradiation field is equal to 30 mm×30 mm. Beam energy degrade with rotating aluminum foils is installed in the chamber, so that the uniformity damage can be obtained within a certain range of the target materials. The preliminary ion irradiation experiments showed that this facility is suitable for exploring radiation effects on the refractory metals as well as other potential TMSR materials.

Sweet cherry (Prunus avium L.) is a deciduous tree originating in the Black Sea/Caspian Sea region where Asia and Europe converge. Being highly valued for its timber and fruit, sweet cherry has been cultivated and naturalized on all continents. Over the past decade, the area of sweet cherry cultivation increased rapidly in China and has reached 140,000 ha. In April 2013, sweet cherry trees (cv. Summit) exhibiting floral virescence symptoms were observed in two orchards located in suburban Taian, Shandong Province, China. The diseased trees developed flowers having white petals with green veins or abnormal floral structures having cupped, green petals. The affected flowers failed to set fruit. A month following the first appearance of the virescence symptoms, the diseased trees became wilted and eventually died. Leaf and stem samples were collected from nine symptomatic and two nearby symptomless trees. Total DNA was extracted from each sample using the Plant Quick DNA Extract Kit (TianGen, Beijing, China). Nested-PCR was carried out using phytoplasma-universal primer pairs P1/P7 and R16F2n/R16R2 (1). All PCR assays with DNA templates from symptomatic samples yielded an amplicon of 1.25 kb, corresponding to the full-length F2nR2 region of phytoplasmal 16S rDNA. No amplicon was generated in PCRs containing DNA templates from symptomless plants. The amplicons were cloned into plasmid vector pMD18-T (TaKaRa, Dalian, China) and sequenced. The obtained sequences were nearly identical, and a representative sequence was deposited into GenBank (Accession No. KF268424). An analysis of the sequence through the iPhyClassifier (4) revealed that the sweet cherry virescence (SCV) disease was associated with infection by a phytoplasma closely related to the reference strain of ‘Candidatus Phytoplasma ziziphi.’ The 16S rDNA F2nR2 region of the SCV phytoplasma shared 99.8% nucleotide sequence identity with that of ‘Candidatus Phytoplasma ziziphi’ reference strain (Accession No. AB052876). A computer-simulated restriction fragment length polymorphism (RFLP) analysis of the SCV phytoplasma 16S rDNA F2nR2 sequence with a set 17 restriction enzymes (3) resulted in a collective RFLP profile identical to the reference pattern of the elm yellows phytoplasma group, subgroup B (16SrV-B). Phytoplasmal diseases of sweet cherry were reported previously in Europe and the etiological agents were phytoplasmas of other groups, including the aster yellows group (16SrI), the X-disease group (16SrIII), and the apple proliferation group (16SrX) (2). To our knowledge, this is the first report of a phytoplasmal disease of sweet cherry in China, and the SCV phytoplasma is a new member of the subgroup 16SrV-B. Presence of 16SrV-B phytoplasmas and their etiological association with various plant diseases in China have been reported previously; affected host plants included jujube, hemp fiber, paper mulberry, Chinese cherry, plum, apricot, red barberry, clover, dianthus, elm, and sunshine tree. Our identification of the SCV phytoplasma expands the known plant host range of the 16SrV-B phytoplasma lineage. The impact of the SCV phytoplasma in the regional ecosystem and in sweet cherry production is being assessed. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) S. Paltrinieri et al. Acta Hort. 550:365, 2001. (3) W. Wei et al. Int. J. Syst. Evol. Microbiol. 57:1855, 2007. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Nanocrystalline diamond (NCD) films were grown on silicon substrates by hot filament chemical vapor deposition in Ar/N2/CH4 gas mixtures. The effects of seeding process prior to deposition, the total gas pressure, and concentration of nitrogen on the grain size, morphology and bonding nature in HFCVD technique were investigated. The results indicated that a low total gas pressure is favorable for nanosized diamond crystallites. Films micrograph obtained from scanning electron microscopy showed diamond nanograins elongated with the addition of nitrogen in the plasma. Crystal structure investigations were carried out by X-ray diffraction measurements for deposited films. An increase in the size of crystallite is also observed from XRD measurements in NCD film when nitrogen was added in plasma. From Raman spectra, it was observed that the relative intensity of G peak increases indicating more graphite content after nitrogen added in the plasma. The effects of the nitrogen incorporation in nanocrystalline films in HFCVD are discussed.

Amorphous structure transformation of multiwalled carbon nanotubes (MWCNTs) irradiated by 70 keV protons at room temperature was investigated.It was found that some of the proton-irradiated MWCNTs were covered with homogeneous amorphous structure with the inner tube walls in graphite structure.Moreover,the amorphous structure continuously proceeds and the graphite structure was reduced during the proton irradiation until the irradiated MWCNTs become amorphous nanowires with a hollow structure.The proton-induced structural transformation of MWCNTs was a unique graphite-to-amorphous structural transition from the outer walls to the inner walls of the irradiated MWCNTs.The structural evolutionary mechanism of proton-beam-irradiated MWCNTs has been discussed.

Ion beam irradiation is usually thought to induce defects and disordered structures in materials and then to destroy the properties of the materials.However,our recent experiments about the ion beam irradiation on carbon nanotubes(CNTs)indicate that the ion beam modification mechanism of CNTs is completely different from traditional one of bulk materials,and ion beam irradiation can lead to self-organized structures in CNTs,such as amorphous junctions and CNT junctions.Moreover,the irradiated CNTs exhibit a improved conductivity and an enhanced field emission.

Carbon nanotubes (CNTs) irradiated by Ar ion beams at elevated temperature were studied. The irradiation-induced defects in CNTs are greatly reduced by elevated temperature. Moreover, the two types of CNT junctions, the crossing junction and the parallel junction, were formed. And the CNT networks may be fabricated by the two types of CNT junctions. The formation process and the corresponding mechanism of CNT networks are discussed.

Controlled evolution of silicon nanocone arrays induced by Ar+ sputtering at room temperature, using the coating carbon as a mask, is demonstrated. The investigation of scanning electron microscopy indicates that the morphology of silicon nanostructures can be controlled by adjusting the thickness of the coating carbon film. Increasing the thickness of the coating carbon film from 50–60 nm, 250–300 nm and 750–800 nm to 1500 nm, the morphologies of silicon nanostructures are transformed from smooth surface ripple, coarse surface ripple and surface ripple with densely distributed nanocones to nanocone arrays with a high density of about 1 × 109 – 2 × 109 cm−2.

Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated. It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose. Similar behavior was observed in terahertz range, where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose. The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.

Diamond nanorods (DNRs) have been prepared by hydrogen plasma post-treatment of nanocrystalline diamond films in radio-frequency (RF) plasma-assisted hot-filament chemical vapor deposition. Single-crystal diamond nanorods with diameters of 3–5 nm and with lengths up to 200 nm grow under hydrogen plasma irradiation of nanocrystalline diamond thin film on the Si substrate at high temperatures. The DNRs growth occurs from graphite clusters. The graphite clusters arises from the etching of diamond carbon atoms and from the non-diamond phase present in the parent film. The graphite clusters recrystallized to form nanocrystalline diamonds which further grow for diamond nanorods. The negative applied bias and surface stresses are suggested to support one-dimensional growth. The growth direction of diamond nanorods is perpendicular to the (1 1 1) crystallographic planes of diamond. The studies address the structure and growth mechanism of diamond nanorods.

Si nanocone array was fabricated under oblique ion beam bombardment on diamond film-masked Si substrates at room temperature.SEM images of the ion sputtered samples showed that the Si nanocone density was determined by density of the diamond particles on the Si substrate, and topography of the Si nanocones was closely linked with the beam incidence.By increasing the incidence angle from 30° to 75°, apex angle of the Si nanocone decreased from 73° to 23°, and aspect ratio of the Si nanocone increased from 500 nm/360 nm to 2400 nm/600 nm.It was believed that the formation of silicon nanocones using the diamond film mask was attributed to the lower sputtering rate of diamond compared to Si substrate.With increasing incidence angle, the decreasing apex angle and increasing aspect ratio of Si nanocone were attributed to decreased effective diffusion coefficiency and increased sputtering yield induced by the ion beams.

In this investigation, diamond thin films with grain size ranging from 50 nm to I pm deposited using hot filament chemical vapor deposition (HFCVD) have been analyzed by elastic recoil detection analysis (ERDA) for determining hydrogen concentration. Hydrogen concentration in diamond thin films increases with decreasing grain size. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed that part of this hydrogen is bonded to carbon forming C-H bonding. Raman spectra also indicated the increase of non diamond phase with the decrease in crystallite size. Incorporation of hydrogen in the samples and increase of hydrogen content in nanocrystalline sample are discussed. Large separation between filament and substrate used for the synthesis of nanocrystalline film helped to understand the large incorporation of hydrogen in nanocrystalline diamond films during growth. The study addresses the hydrogen trapping in different samples and higher hydrogen concentration in nanocrystallites by considering the synthesis conditions, growth mechanisms for different grain sized diamond films and from the quality of CVD diamond films. (C) 2009 Elsevier B.V. All rights reserved.

The electron field emission of carbon nanotubes (CNTs) has been enhanced by Si ion beam irradiation. The defects generated by ion beam irradiation and the absorbed molecules on the CNTs were responsible for the enhancement of electron field emission. This investigation provides a possible way to improve the electron field emission properties of CNTs and understand the mechanism of electron field emission enhancement of CNTs.

A method for improving the electrical conductivity of carbon nanotube (CNT) sheets by ion beam irradiation is reported. CNT sheets prepared by a vacuum filtration method were irradiated by Ar and H ion beams at different temperatures. The electrical conductivity of the irradiated CNT sheets at a temperature of 800K can be improved. The conductivity improvement can be ascribed to the formation of covalent bond crosslinks between CNTs induced by the ion beam irradiation at the elevated temperature.

The graphite-to-amorphous structural transformation of multiwalled carbon nanotubes (MWCNTs) was investigated under 70 keV proton beam irradiation at room temperature. it was found that under proton irradiation some amorphous structure homogeneously covers the inner tube walls with graphite structure in irradiated MWCNTs. Moreover, the amorphous structure continuously proceeds and the graphite structure is reduced during the proton irradiation until the irradiated MWCNTs become amorphous nanowires with a hollow structure. The proton irradiation induced structural transformation of MWCNTs was a unique graphite-to-amorphous structural transition from the outer walls to the inner walls of the irradiated MWCNTs. The structural evolutionary mechanism of proton-beam-irradiated MWCNTs has been discussed. (C) 2009 Elsevier B.V. All rights reserved.

In this paper, effect of pressure on deposition temperature for hot filament chemical vapor deposition of diamond thin films was investigated. SEM images show that diamond film of small grain size can be deposited at 500°C by decreasing the pressure from 5.32 kPa to 0.67 kPa. Raman spectra show that the quality of the film deposited at 0.67 kPa and 500°C was as good as that of the film deposited at 5.32 kPa and 700°C. We believe that the deposition of diamond film at low temperature and low pressure is due to the effect of pressure on the concentrations and kinetic energy of the active species near the substrate surface. Compared to the situations with higher pressure, the active species at 0.67 kPa arrive at the substrate surface with higher concentration, which makes it possible for the high-quality diamond films of small grain size can be deposited at very low temperature (500°C).