Measurement of XeI and XeII velocity in the near exit plane of a low-power Hall effect thruster by light induced fluorescence spectroscopy

Near exit plane non-resonant light induced fluorescence spectroscopy is performed in a Hall effect low-power Xenon thruster at discharge voltage of 250V and anode flow rate of 0.7mg/sec. Measurement of the axial and radial velocity components are performed, exciting the 6s[3/2]_2-->6p[3/2]_2 transition at 823.16nm in XeI and the 5d[4]_(7/2)-->6p[3]_(5/2) transition at 834.724nm in XeII. No significant deviation from the thermal velocity is observed for XeI. Two most probable ion velocities are registered at a given position with respect to the thruster axis, which are mainly attributed to different areas of creation of ions inside the acceleration channel. The spatial resolution of the set-up is limited by the laser beam size (radius of the order of 0.5mm) and the fluorescence collection optics, which have a view spot diameter of 8mm.Comment: 6 pages, 8 figure

Ion dynamic characterization using phase-resolved laser-induced fluorescence spectroscopy in low power Hall effect thruster

Valuable information on the dynamics of the plasma constituents in Hall effect thrusters can be extracted with minimally intrusive means such as time-resolved light-induced fluorescence diagnostics. In general, maps of the ion velocity distribution function are built for plasma characterization using different techniques. One of the most relevant phenomena under investigation is the so called breathing mode that is characterized by intense and quasi-periodic oscillation of the discharge current. The goal of this work is to propose a new approach for plasma dynamic studies based on parallelized laser-induced fluorescence spectroscopy with phase-resolution within the breathing period.Comment: 6 pages, 11 figures, 29 reference

advanced electric propulsion diagnostic tools at iom

Abstract Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1] , which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1] , [4] ), in two different vacuum facilities

A Brassica rapa Linkage Map of EST-based SNP Markers for Identification of Candidate Genes Controlling Flowering Time and Leaf Morphological Traits

For identification of genes responsible for varietal differences in flowering time and leaf morphological traits, we constructed a linkage map of Brassica rapa DNA markers including 170 EST-based markers, 12 SSR markers, and 59 BAC sequence-based markers, of which 151 are single nucleotide polymorphism (SNP) markers. By BLASTN, 223 markers were shown to have homologous regions in Arabidopsis thaliana, and these homologous loci covered nearly the whole genome of A. thaliana. Synteny analysis between B. rapa and A. thaliana revealed 33 large syntenic regions. Three quantitative trait loci (QTLs) for flowering time were detected. BrFLC1 and BrFLC2 were linked to the QTLs for bolting time, budding time, and flowering time. Three SNPs in the promoter, which may be the cause of low expression of BrFLC2 in the early-flowering parental line, were identified. For leaf lobe depth and leaf hairiness, one major QTL corresponding to a syntenic region containing GIBBERELLIN 20 OXIDASE 3 and one major QTL containing BrGL1, respectively, were detected. Analysis of nucleotide sequences and expression of these genes suggested possible involvement of these genes in leaf morphological traits

The reproductive capacity of Monk Parakeets Myiopsitta monachus is higher in their invasive range

Breeding parameters for Monk Parakeets Myiopsitta monachus nesting in Barcelona, Spain, were collected for 651 nests over five breeding seasons. This invasive population has a high reproductive capacity compared with the species in the native range: fledging success was double, the percentage of pairs attempting second broods three times higher and 55% of first-year birds bred compared with almost zero in South America

Perfil comparativo do transcriptoma em Psidium guajava L. e Psidium friedrichsthalianum fornece expressão gênica em resposta à resistencia ao Meloidogyne enterolobii.

A goiabeira (Psidium guajava L.), espécie tropical da América do Sul, é considerada uma frutífera de relevância econômica no Brasil. Entretanto, interações sinérgicas entre o nematoide Meloidogyne enterolobii e o fungo Fusarium solani nas raízes destas lantas acarretam a formação de galhas e apodrecimento das raízes. Nesse contexto, P. friedrichsthalianum (Araçá Costa Rica) foi identificada como espécie resistente ao nematoide. Para melhor entender a relação de suscetibilidade e resistência à infecção por M. enterolobii, foi realizado o sequenciamento do transcriptoma de folhas das espécies P. guajava L. e P. friedrichsthalianum (de plantas controle e de plantas inoculadas com o nematoide) pela metodologia de RNA-seq, seguida pela montagem de sequências. Foram obtidos 60.836 contigs com N50 de 786 pb utilizando o sequenciador ILLUMINA (Illumina HiSeq 2000). As transcrições foram anotadas via Genomes Kyoto (KEGG) e Gene Ontology (GO). Para as quatro bibliotecas disponibilizadas no NCBI (National Center for Biotetchnology Information) sob acesso PRJNA779437, realizou-se o mapeamento comparativo com o genoma de Eucalyptus grandis v2.0, por meio de ferramentas de bioinformática. Considerando os genes que possuem anotação no Phytozome e com expressão acima de 50 TPM, construíram-se um heatmap e uma rede de interação do tipo interactoma, com 68 genes. Desses, 21 estão intimamente relacionados à regulação dos fotossistemas I e II. Os demais estão envolvidos na produção de clorofila, rubisco e cadeia transportadora de elétrons. Também verificou-se alteração da expressão gênica relacionada às enzimas do estresse oxidativo, com redução de catalase, peroxidase e tiredoxina (mRNA splicing) em plantas de P. guajava inoculadas e aumento das mesmas enzimas em P. friedrichsthalianum na mesma condição. Com isso, sugere-se a ocorrência de um efeito sistêmico nas folhas de Psidium spp. como resposta à infecção nas raízes, refletido por alterações nas vias fotossintéticas. Adicionalmente, também ocorre alteração da expressão de genes relacionados ao metabolismo fenólico, atuante na defesa de plantas contra os estresses bióticos e abiótico

Repression of Flowering by the miR172 Target SMZ

The flowering repressors SMZ and FLM, members of the AP-2 and MADS domain transcription factor families, unexpectedly work together to regulate flowering time via their effects on expression of the FT gene