An exploration on electron bunching of ionization induced self-injection in laser wakefield accelerators

Plasma-based wakefield accelerator is attractive for generating quasi-monoenergetic electron beams using the bubble regime. The bubble is formed by an intense driver, which propagates through the plasma and expels all electrons transversely, creating a cavity free of cold plasma electrons that trailing behind the driver. Self-injection is applicable in the bubble regime, which can produce bunches of quasi-monoenergetic electrons. (1) Such electron bunching structure can be diagnosed with coherent transition radiation and may be exploited to generate powerful high frequency radiation [16].This thesis focuses on electron bunching phenomenon through WAKE simulations and theoretical analysis. The simulation is completed under laser-driven field ionization wakefield acceleration. The code is improved by taking into consideration the high frequency property of laser driver in wakefield acceleration. Finer grid size is introduced to the ionization injection part of WAKE, for increasing simulation accuracy without much sacrifice of programming efficiency. Various conditions for optimal bunching in the trapped electrons are explored computationally and analytically.Physic

Exploring transcriptional signalling mediated by OsWRKY13, a potential regulator of multiple physiological processes in rice

BACKGROUND Rice transcription regulator OsWRKY13 influences the functioning of more than 500 genes in multiple signalling pathways, with roles in disease resistance, redox homeostasis, abiotic stress responses, and development. RESULTS To determine the putative transcriptional regulation mechanism of OsWRKY13, the putative cis-acting elements of OsWRKY13-influenced genes were analyzed using the whole genome expression profiling of OsWRKY13-activated plants generated with the Affymetrix GeneChip Rice Genome Array. At least 39 transcription factor genes were influenced by OsWRKY13, and 30 of them were downregulated. The promoters of OsWRKY13-upregulated genes were overrepresented with W-boxes for WRKY protein binding, whereas the promoters of OsWRKY13-downregulated genes were enriched with cis-elements putatively for binding of MYB and AP2/EREBP types of transcription factors. Consistent with the distinctive distribution of these cis-elements in up- and downregulated genes, nine WRKY genes were influenced by OsWRKY13 and the promoters of five of them were bound by OsWRKY13 in vitro; all seven differentially expressed AP2/EREBP genes and six of the seven differentially expressed MYB genes were suppressed by in OsWRKY13-activated plants. A subset of OsWRKY13-influenced WRKY genes were involved in host-pathogen interactions. CONCLUSION These results suggest that OsWRKY13-mediated signalling pathways are partitioned by different transcription factors. WRKY proteins may play important roles in the monitoring of OsWRKY13-upregulated genes and genes involved in pathogen-induced defence responses, whereas MYB and AP2/EREBP proteins may contribute most to the control of OsWRKY13-downregulated genes.This work was supported by grants from the National Program of High Technology Development of China, the National Program on the Development of Basic Research in China, and the National Natural Science Foundation of China

2,6-Bis(2-chloro­benzyl­idene)cyclo­hexanone

In the title mol­ecule, C20H16Cl2O, the central cyclo­hexa­none ring adopts an envelope conformation. The two aromatic rings form a dihedral angle of 30.0 (1)°. The crystal packing exhibits weak inter­molecular C—H⋯O hydrogen bonds and short Cl⋯O contacts [3.213 (3) Å]

The influence of particle size distribution on measures of states for granular materials and implications for small strain stiffness

Gap-graded soils are poorly graded soils, which have a deficiency of certain particle sizes, one example is a mixture of coarse and finer sand grains with no intermediate-sized particles. While current knowledge of soil behaviour has been mainly established by considering the response of well-graded soils, natural soils encountered in geotechnical engineering practice can be gap-graded. In this research, both numerical and experimental approaches are applied to study the mechanical behaviour of gap-graded soils; materials with continuous particle size distributions are also investigated using the same analytical tools to provide a benchmark against which the gap-graded materials can be considered. Using discrete element method (DEM) simulations, the stress transmission within granular materials with a broad range of particle size distributions was investigated. The first series of analyses took a rather simplistic binary approach and considered grains to be either active or inactive grains. These analyses showed that for both continuous and gap-graded soils, the proportion by volume of inactive grains can be sufficiently large to influence widely used measures of state such as void ratio and bulk density. The nature of the stress transmission was then analysed, which shows that for materials with a continuous, linear gradation, the proportion of stress carried by a particle aligns with its particle volume; this is not the case in gap-graded soils. Using DEM, the small-strain stiffness of gap-graded soils was considered in detail. The results show that the particle-scale distribution of stress influences the stiffness of gap-graded soils. A new semi-empirical state variable, e_α, was proposed that weights the contribution of particles to the solids volume used in calculating e by the particle stress. The strong correlation of G_0 with e_α shows how the heterogeneity of stress influences stiffness. The difference between the stiffness obtained from the quasi-static small strain probes and the stiffness obtained from the dynamic bender element tests can qualitatively capture the proportion of inactive particles. The potential to use this observation in physical laboratory experiments was explored.Open Acces

Analysis of oilseed glucosinolates and their fate during pressing or dehulling

Brassica carinata (A.) Braun and Camelina sativa (L.) Crantz are two re-emerging oilseed crops of the Brassicaceae family that are being adapted for cultivation in western Canada. Both seeds of these species reportedly accumulate considerable amounts of sulfur-containing secondary metabolites called glucosinolates. The purpose of the current work was to gain knowledge of the occurrence and distribution of glucosinolates during primary processing of these oilseeds, including during pressing and dehulling. In the first study, a reversed phase HPLC method was developed for the analysis of sinigrin, the major glucosinolate in B. carinata. Both C18 columns selected were able to separate the compound with an isocratic eluent containing 100% tetramethylammonium bromide (10 mM, pH 5) delivered at 1 mL/min at a column temperature of 25oC. These chromatographic conditions were applied and sinigrin concentration of whole B.carinata seed was estimated to be 29 μg/mg. Average matrix effect was estimated to be 104% that was caused by other components in the B. carinata seed matrix. In the second study, high concentrations of glucosinolates were detected and identified in fractions of C. sativa seeds using HPLC-ESI-MS. Methods for extraction, isolation, and purification of three individual glucosinolates from these fractions are reported. Quantitation of total glucosinolates was performed on proton NMR using DMF as an internal standard. Quantitation of individual glucosinolates was achieved by using MS extracted ion chromatogram data. Total glucosinolates were found in C. sativa whole seed at a concentration of 14 μg/mg, and glucocamelinin, the major glucosinolate, constituted 65% of the total amount. In addition, a dehulling treatment was applied to C. sativa seeds, from which both oil content and crude protein content increased after dehulling of the seeds

Fiberscopic Imaging of the Pediatric Nasopharynx

This study describes the endoscopic findings about the size of the adenoid tissue and the condition of the nasopharyngeal orifice of the eustachian tube. Results confirmed that only fiberscopic examination allows a thorough inspection of the nasopharyngeal anatomy to make a correct diagnosis and design therapeutic planning. When the presence of adenoid hypertrophy resulting in nasal obstruction, snoring, and/or otitis media was confirmed endoscopically, adenoidectomy proved to be highly efficacious in relieving these symptoms

Qualitative Fault Detection and Hazard Analysis Based on Signed Directed Graphs for Large-Scale Complex Systems

Nowadays in modern industries, the scale and complexity of process systems are increased continuously. These systems are subject to low productivity, system faults or even hazards because of various conditions such as mis-operation, equipment quality change, externa