THEORY RESEARCH ON APPLICATION OF CT TECHNOLOGY TO SHIELDED NUCLEAR MATERIAL DISCRIMINATION

Abstract Smuggling of nuclear material is a serious threat to security of international society. Formal research on nuclear material discrimination can fulfil customs inspection requirement. This paper designs a situation that nuclear material which is packaged and shielded by heavy metal need to be discriminated accurately on the condition that the object being detected cannot be dismantled. Calculation results prove nuclear material could be discriminated accurately while the ideal condition is fulfilled. If multi-energy X-ray source is used the discrimination accuracy is declined. However the accuracy could be improved while energy spectrum shaping technique is used

Experiments on bright field and dark field high energy electron imaging with thick target material

Using a high energy electron beam for the imaging of high density matter with both high spatial-temporal and areal density resolution under extreme states of temperature and pressure is one of the critical challenges in high energy density physics . When a charged particle beam passes through an opaque target, the beam will be scattered with a distribution that depends on the thickness of the material. By collecting the scattered beam either near or off axis, so-called bright field or dark field images can be obtained. Here we report on an electron radiography experiment using 45 MeV electrons from an S-band photo-injector, where scattered electrons, after interacting with a sample, are collected and imaged by a quadrupole imaging system. We achieved a few micrometers (about 4 micrometers) spatial resolution and about 10 micrometers thickness resolution for a silicon target of 300-600 micron thickness. With addition of dark field images that are captured by selecting electrons with large scattering angle, we show that more useful information in determining external details such as outlines, boundaries and defects can be obtained.Comment: 7pages, 7 figure

Colour break in reverse bicolour daffodils is associated with the presence of Narcissus mosaic virus

<p>Abstract</p> <p>Background</p> <p>Daffodils (<it>Narcissus pseudonarcissus</it>) are one of the world's most popular ornamentals. They also provide a scientific model for studying the carotenoid pigments responsible for their yellow and orange flower colours. In reverse bicolour daffodils, the yellow flower trumpet fades to white with age. The flowers of this type of daffodil are particularly prone to colour break whereby, upon opening, the yellow colour of the perianth is observed to be 'broken' into patches of white. This colour break symptom is characteristic of potyviral infections in other ornamentals such as tulips whose colour break is due to alterations in the presence of anthocyanins. However, reverse bicolour flowers displaying colour break show no other virus-like symptoms such as leaf mottling or plant stunting, leading some to argue that the carotenoid-based colour breaking in reverse bicolour flowers may not be caused by virus infection.</p> <p>Results</p> <p>Although potyviruses have been reported to cause colour break in other flower species, enzyme-linked-immunoassays with an antibody specific to the potyviral family showed that potyviruses were not responsible for the occurrence of colour break in reverse bicolour daffodils. Colour break in this type of daffodil was clearly associated with the presence of large quantities of rod-shaped viral particles of lengths 502-580 nm in tepals. Sap from flowers displaying colour break caused red necrotic lesions on <it>Gomphrena globosa</it>, suggesting the presence of potexvirus. Red necrotic lesions were not observed in this indicator plant when sap from reverse bicolour flowers not showing colour break was used. The reverse transcriptase polymerase reactions using degenerate primers to carla-, potex- and poty-viruses linked viral RNA with colour break and sequencing of the amplified products indicated that the potexvirus <it>Narcissisus mosaic virus </it>was the predominant virus associated with the occurrence of the colour break.</p> <p>Conclusions</p> <p>High viral counts were associated with the reverse bicolour daffodil flowers that were displaying colour break but otherwise showed no other symptoms of infection. <it>Narcissus mosaic virus </it>was the virus that was clearly linked to the carotenoid-based colour break.</p

Induction of vacuolar invertase inhibitor mRNA in potato tubers contributes to cold-induced sweetening resistance and includes spliced hybrid mRNA variants

Cold storage of tubers of potato (Solanum tuberosum L.) compromises tuber quality in many cultivars by the accumulation of hexose sugars in a process called cold-induced sweetening. This is caused by the breakdown of starch to sucrose, which is cleaved to glucose and fructose by vacuolar acid invertase. During processing of affected tubers, the high temperatures involved in baking and frying cause the Maillard reaction between reducing sugars and free amino acids, resulting in the accumulation of acrylamide. cDNA clones with deduced proteins homologous to known invertase inhibitors were isolated and the two most abundant forms, termed INH1 and INH2, were shown to possess apoplastic and vacuolar localization, respectively. The INH2 gene showed developmentally regulated alternative splicing, so, in addition to the INH2α transcript encoding the full-length protein, two hybrid mRNAs (INH2β*A and INH2β*B) that encoded deduced vacuolar invertase inhibitors with divergent C-termini were detected, the result of mRNA splicing of an upstream region of INH2 to a downstream region of INH1. Hybrid RNAs are common in animals, where they may add to the diversity of the proteome, but are rarely described in plants. During cold storage, INH2α and the hybrid INH2β mRNAs accumulated to higher abundance in cultivars resistant to cold-induced sweetening than in susceptible cultivars. Increased amounts of invertase inhibitor may contribute to the suppression of acid invertase activity and prevent cleavage of sucrose. Evidence for increased RNA splicing activity was detected in several resistant lines, a mechanism that in some circumstances may generate a range of proteins with additional functional capacity to aid adaptability

A manually annotated Actinidia chinensis var. chinensis (kiwifruit) genome highlights the challenges associated with draft genomes and gene prediction in plants

Most published genome sequences are drafts, and most are dominated by computational gene prediction. Draft genomes typically incorporate considerable sequence data that are not assigned to chromosomes, and predicted genes without quality confidence measures. The current Actinidia chinensis (kiwifruit) 'Hongyang' draft genome has 164\ua0Mb of sequences unassigned to pseudo-chromosomes, and omissions have been identified in the gene models

Cytokinins and phase change in Pinus radiata : morphological, physiological and molecular studies : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology at Massey University, Palmerston North, New Zealand

Phase change in higher plants is a developmental process during which changes occur at morphological, physiological and molecular levels. In Pinus radiata, buds of juvenile trees produce photosynthetically functional primary needles while buds from mature trees do not produce such primary needles. Cytokinin, however, causes production of primary needles from mature buds in vitro (Horgan, 1987). Pursuing this observation, morphological and anatomical examinations of the buds were carried out using light microscopy. The results showed that the cytokinin-induced transition from mature to juvenile bud morphology may be through resetting the fate of fascicle meristems and/or foliar primordia. To determine if a correlation existed between the endogenous cytokinin content and the maturation status of the buds, buds from the juvenile and mature P. radiata were analysed using a range of modern techniques, including column complex purification, immunoaffinity purification, normal and reverse HPLC, radioimmunoassay and electrospray tandem mass spectrometry. A wide spectrum of endogenous cytokinins were detected in the bud tissues, including five novel forms discovered in this work. Quantitative analyses revealed a general trend with seedling buds > juvenile (J4) buds > mature (M4) buds > mature (M8) buds for the combined concentration of free base and riboside cytokinins. High concentrations of phosphorylated cytokinins were found in the mature buds but not the juvenile buds. Novel cytokinin glucosides were the most abundant forms in the buds, with zeatin-9-(glucopyranosyl-1,3-ribosyl) and dihydrozeatin-9-(glucopyranosyl-1,3-ribosyl) being higher in the mature buds and isopentenyladenine-9-(glucopyranosyl-l,3-ribosyl) being higher in the juvenile buds. Overall, particular patterns of cytokinins in the field buds reflected the maturation status of the buds. Extensive metabolism of 6-benzylaminopurine occurred, including the production of the novel forms, 6-benzylaminopurine-9-(glucopyranosyl-1,3-ribosyl) and phosphorylated 6-benzylaminopurine-9-(glucopyranosyl-1,3-ribosyl), during the in vitro 'rejuvenation' of mature buds to the juvenile phenotype. Among the metabolites, the abundance of 6-benzylaminopurine, 6-benzylaminopurine riboside and 6-benzylaminopurine-9-(glucopyranosyl-1,3-ribosyl) was high while phosphorylated forms were very low over the duration of the experiment. The patterns of metabolites reflected the patterns of endogenous cytokinins observed in juvenile buds. The results also indicated that 6-benzylaminopurine did not regulate phase-specific traits by increasing endogenous cytokinins. Molecular tools were used to clone cytokinin-responsive genes which may also be involved in the regulation of phase change. A cDNA sequence (Prcr5) was cloned using a modified mRNA differential display technique. Northern analyses showed that cytokinin promoted and maintained the expression of Prcr5 at a high level during rejuvenation of the mature buds in vitro. The deduced PrCR5 protein sequence displays homology to Ginseng RNases and PR-10. A possible function of the Prcr5 gene in the regulation of phase change is discussed. A cDNA sequence (Prcab) coding for a chlorophyll a/b binding protein was also cloned. Although expression of the cab gene has been reported to be associated with phase change in other species, no such change was observed in P. radiata

Single-system pulmonary langerhans cell histiocytosis with only tracheobronchial involvement: a case report

Abstract Background Pulmonary Langerhans cell histiocytosis (PLCH) only with airway involvement manifested as diffuse thickening of the tracheobronchial walls is rare. Case report A 26-year-old male was admitted to the hospital with progressive wheezing, cough, and a source of blood in sputum after activity. He had no history of smoking. Chest computed tomography showed airway stenosis of different degrees with tracheobronchial wall thickening, and fiberoptic bronchoscopy demonstrated multiple nodular neoplasms in tracheobronchial, while the pulmonary parenchyma was normal. The patient’s condition partially improved after excision of partial lesions by fiberoptic bronchoscope. Histopathological results showed that CD1a and S-100 immunohistochemical staining was positive, and the molecular pathological results suggested that the BRAF V600E mutation, thus confirming the diagnosis of PLCH. The treatment of partial resection and systemic chemotherapy is effective. Conclusions The possibility of PLCH needs to be considered when diffuse tracheobronchial lesions without lung parenchyma involvement are encountered, which provides experience for early clinical diagnosis and adequate treatment

New insight into the structures and formation of anthocyanic vacuolar inclusions in flower petals

Abstract Background Although the biosynthetic pathways for anthocyanins and their regulation have been well studied, the mechanism of anthocyanin accumulation in the cell is still poorly understood. Different models have been proposed to explain the transport of anthocyanins from biosynthetic sites to the central vacuole, but cellular and subcellular information is still lacking for reconciliation of different lines of evidence in various anthocyanin sequestration studies. Here, we used light and electron microscopy to investigate the structures and the formation of anthocyanic vacuolar inclusions (AVIs) in lisianthus (Eustoma grandiflorum) petals. Results AVIs in the epidermal cells of different regions of the petal were investigated. Three different forms of AVIs were observed: vesicle-like, rod-like and irregular shaped. In all cases, EM examinations showed no membrane encompassing the AVI. Instead, the AVI itself consisted of membranous and thread structures throughout. Light and EM microscopy analyses demonstrated that anthocyanins accumulated as vesicle-like bodies in the cytoplasm, which themselves were contained in prevacuolar compartments (PVCs). The vesicle-like bodies seemed to be transported into the central vacuole through the merging of the PVCs and the central vacuole in the epidermal cells. These anthocyanin-containing vesicle-like bodies were subsequently ruptured to form threads in the vacuole. The ultimate irregular AVIs in the cells possessed a very condensed inner and relatively loose outer structure. Conclusion Our results strongly suggest the existence of mass transport for anthocyanins from biosynthetic sites in the cytoplasm to the central vacuole. Anthocyanin-containing PVCs are important intracellular vesicles during the anthocyanin sequestration to the central vacuole and these specific PVCs are likely derived directly from endoplasmic reticulum (ER) in a similar manner to the transport vesicles of vacuolar storage proteins. The membrane-like and thread structures of AVIs point to the involvement of intravacuolar membranes and/or anthocyanin intermolecular association in the central vacuole.</p