1,972 research outputs found
Assessment of Models for Near Wall Behavior and Swirling Flows in Nuclear Reactor Sub-system Simulations
No full textAccurate simulation of turbulence remains one of the most challenging problems in nuclear reactor analysis and design. Due to limitations in computing resources, Reynolds averaged Navier Stokes models (RANS) continue to play an important role in reactor simulations. The Consortium for advanced simulations of light water reactors (CASL) is a Department of Energy technology hub that is investing in research and developmentof a state-of-the-art computational fluid dynamics capabilityto meet the challenges of turbulent simulation of nuclear reactors. In this presentation, we assess several RANS eddy viscosity models appropriate for single-phase incompressible turbulent flows. Specifically, we compare the single equation Splalart-Allmaras to several variations of the model. The assessment takes into consideration elements of full system reactor cores such as complex geometries, heterogeneous meshes, swirling flow, near wall flow behavior, heat transfer and robustness issues. The goal of this strategically oriented assessment is to provide an accurate and robust turbulent simulation capability for the CASL community. Metrics of performance will be constructed by comparing different models on a strategically chosen set of problems that represent reactor core sub-systems
Eatonigenia zhangi Sun, Luo & Zhou, 2016, sp. nov.
No full textEatonigenia zhangi sp. nov. Eatonigenia chaperi Zhang, 1988: 68 (male, female, subimago) (nec. Hexagenia chaperi Navás, 1935: 99, misidentification); Zhang et al., 1995: 74; She et al., 1995: 80; You and Gui, 1995: 91. Diagnosis. The new species can be distinguished from the other species of the genus based on the following characteristics: in males, larger and more colorful body, slightly projected apex of penis and three tips of gonopores; in nymphs, larger and paler body, smaller fore-claw and asymmetrical labrum. Nymph (in alcohol, not mature, Figs. 1, 3 A): Body length 20.0 mm, cerci 4.0–6.0 mm, terminal filament 3.0 mm. Body ivory pale, with golden setae on most parts of body. Head (Figs. 1, 3 A, 5A): Length of frontal processes slightly shorter than width, its anterior margin smoothly convex and narrower than posterior margin; all free margins with dense golden setae; base of antenna projected forwards with relatively long setae on supra-antennal surface; scape of antenna slightly longer than pedicel, the latter with setae on basal half; flagella with sparse setae; length of antenna subequal to head width; compound eyes dark, surrounded with a row of setae; upper half of ocelli pale, lower half dark; area between 3 ocelli slightly pigmented grey; vertex pale (Fig. 5 A). Mouthparts: Labrum generally heart-shaped, asymmetrical; free margins and dorsal surface with long anteriorly directed setae (Figs. 2 A, 5F), ventral surface with short mesally directed setae but no long setae (Fig. 5 G). Mandibles asymmetrical, tusk of left mandible shorter than right in dorsal view; triangular mandibular tusks densely setaceous dorsally and laterally with setae progressively shorter toward apex; outer incisor of left mandible much stronger than inner incisor; apex of both incisors of left mandible divided into 3 denticles; prostheca of left mandible modified into a thick spine, with 2 denticles near apex and a small setal tuft next to prostheca (Fig. 2 B); outer incisor of right mandible slightly stronger than inner incisor, apex of both incisors divided into 3 denticles; prostheca represented as 2 spines, one near inner incisor, other close to mola, an additional small setal tuft between them (Fig. 2 C). Maxillae slender, outer margin with relatively long hair distally, inner margin with long spines and hair, apex of galea-lacinia extended to form 2 large spines (canine and dentiseta) (Fig. 2 D), apex of distal spine (canine) bifurcate (Fig. 2 E); maxillary palp 3-segmented although segmentation between second and third segment indistinct; basal and second segment subequal in length, apical segment slightly longer; basal segment with only 2 long setae on outer margin near apex but other segments with long setae over entire surface, those on inner margin longer; cardo with small spine-like setae (Figs.2 D, 5H). Hypopharynx with lingua slightly emarginated to straight on free margin; surface of lingua and superlinguae with setae, setae more abundant on dorsoapical surface and free margin (Fig. 2 F). Labium with dense setae on paraglossae forming brush-like setal tuft; labial palp 2-segmented, apical segment ca. 2× length of basal segment, basal segment with a thumb-like protuberance, apical segment with fan of long setae and dense spines on surface near apex (Fig. 2 G). Thorax: totally pale to pale grey; pronotum slightly produced laterally, forming a lobe-like structure on anterolateral corners with additional hooked projection and cluster of golden setae, lateral margins with golden setae (Figs. 3 A, 3I, 5A). Length ratio of femur, tibia and tarsus of foreleg 7: 5: 3.6, ratio of midleg 2: 2: 1, hindleg 9.2: 8: 3, midleg shorter than other legs; ventral margin of coxa and trochanter of foreleg with setae, those on trochanter longer and more abundant; forefemur rounded, dorsal surface with 3 longitudinal rows of setae (one median row and rows near margins); foretibia greatly expanded with curved, pointed apex and long setae on margins, sparse and short setae on surfaces (Figs. 3 B, 5C); foretarsus with setae on dorsal surface, apex with cleft, vestigial claw recessed in cleft (Figs. 3 C, 5B); femur and tibia of midleg expanded slightly, tarsi without apical cleft but with slender claw, setal pattern similar to that of foreleg (Figs. 3 D, 5D); all segments of hindleg longer than midleg, coxa with setae on margins and surface, trochanter with very sparse short setae, other segments with longer, and denser setae (Figs. 3 E, 5E); apex of tibia expanded to form large curved projection, its length subequal to tarsus; claw similar to that of midleg but slightly longer and stronger (Fig. 3 F). Abdomen: ivory or pale, with golden hair on lateral margins of terga; gills I forked deeply to one third distance from base (Figs. 3 G, 5I); gills II–VII similar in shape, each of them divided into two lamellae, dorsal lamella broader at base and ventral lamella slender and tapered (Figs. 3 H, 5J); each lamella of gills further divided into large number of fringed filaments; main trachea of gills II–VII clear to pigmented grey to brown; gills VII smaller than anterior pairs; margins of 3 caudal filaments with dense setae, terminal filament shorter than cerci. Male imago (in alcohol, additional characters to those provided by Zhang 1988): Body length 20.0–23.0 mm; forewings 14.0–15.0 mm (Figs. 4 A, 6A), hindwings 6.0–7.0 mm (Figs. 4 B, 6B); body general yellowish brown. Genitalia (Figs. 4 D, 6C): basal segment of forceps broader than distal segments, chestnut pigmented; second segment about 6× length of basal segment, curved with basal one-third light purplish red; apical segment very small, length slightly longer than broad. Apical two-thirds of fused penes slightly sclerotized and reddish brown. except for pale median groove; posterolateral corners of penes expanded apically forming trapezoidal shape (Figs. 4 C, 6D); basal third of penes membranous; sclerotized projections of gonopores with 3 tips, ventral tip slightly smaller than two dorsal tips (Figs. 4 C, 4D, 6E). Eggs (Figs. 8 A, 8B, dissected from female body): Length 0.2 mm, width 0.1 mm; oval, chorionic surface without distinct structure, surface made up of many polygons; small micropyle with long sperm guide visible on equatorial area. Material examined and collecting information. Holotype: 6, Wan-quan River, near Jia-ji Bridge, Qonghai County, Hainan Province, China, leg. Shu-Sheng SHE and Jun ZHANG, 23-V-1986; Paratypes: 3 66, 5 ♀♀, same as the holotype. Others: 10♀♀ subimagos, 22-V-1986; 10♀♀, 13-V-1986, other information same as types; 1 male subimago, 13-VII-2014, about 2 km downstream Jia-ji Bridge, 13-VII-2014, Jian-Hua DAI, Dan ZHOU and Jun- Zhi SUN; 16 larvae, Qionghai, Wan-quan River (110.465784°E, 19.226526°N), 4 km upstream of Jia-ji Bridge, 6- I-2015, Leg. Chang-Fa ZHOU, Jun-Zhi SUN and Yi-Ke HAN. All specimens are deposited in the Institute of Genetic Resources, College of Life Sciences, Nanjing Normal University, P. R. China. The nymphs described here were collected from fine silt and sand substrates of Wan-quan River, Hainan Island, southern China. The river is wide, averaging at least 80 m in width, and more than 300 m at some sections visited (Fig. 7). It has deep water current in all seasons. Other mayflies collected at the same habitat and time include Ephemera and Caenis. This is consistent with the information provided by McCafferty (1973, 1979).Published as part of Sun, Jun-Zhi, Luo, Juan-Yan & Zhou, Chang-Fa, 2016, The nymph, habitat, and status of Eatonigenia in China (Ephemeroptera: Ephemeridae), pp. 381-389 in Zootaxa 4193 (2) on pages 381-386, DOI: 10.11646/zootaxa.4193.2.12, http://zenodo.org/record/16699
Genotype calling in tetraploid species from bi-allelic marker data using mixture models
No full textAbstract Background Automated genotype calling in tetraploid species was until recently not possible, which hampered genetic analysis. Modern genotyping assays often produce two signals, one for each allele of a bi-allelic marker. While ample software is available to obtain genotypes (homozygous for either allele, or heterozygous) for diploid species from these signals, such software is not available for tetraploid species which may be scored as five alternative genotypes (aaaa, baaa, bbaa, bbba and bbbb; nulliplex to quadruplex). Results We present a novel algorithm, implemented in the R package fitTetra, to assign genotypes for bi-allelic markers to tetraploid samples from genotyping assays that produce intensity signals for both alleles. The algorithm is based on the fitting of several mixture models with five components, one for each of the five possible genotypes. The models have different numbers of parameters specifying the relation between the five component means, and some of them impose a constraint on the mixing proportions to conform to Hardy-Weinberg equilibrium (HWE) ratios. The software rejects markers that do not allow a reliable genotyping for the majority of the samples, and it assigns a missing score to samples that cannot be scored into one of the five possible genotypes with sufficient confidence. Conclusions We have validated the software with data of a collection of 224 potato varieties assayed with an Illumina GoldenGate™ 384 SNP array and shown that all SNPs with informative ratio distributions are fitted. Almost all fitted models appear to be correct based on visual inspection and comparison with diploid samples. When the collection of potato varieties is analyzed as if it were a population, almost all markers seem to be in Hardy-Weinberg equilibrium. The R package fitTetra is freely available under the GNU Public License from http://www.plantbreeding.wur.nl/UK/software_fitTetra.html and as Additional files with this article.</p
FA clusters with correlations with HDRS scores for EO vs. LO MDD.
No full text<p>Upper panel (EO): two FA clusters (g, h) with positive correlations (red color) and three FA clusters (i, j, k) with negative correlations (blue color) with HDRS scores. Lower panel (LO): nine FA clusters (H-P), all with negative correlations (blue) with HDRS scores. EO, early onset; LO, later onset; MDD, major depressive disorder; HDRS, Hamilton Depression Rating Scale.</p
Replacement of extracellular anion resulted in different <i>I</i><sub>SC</sub> induced by FA.
No full text<p>Representative <i>I</i><sub>SC</sub> recordings with arrows indicating FA (200 µM) were added in different K-H solutions. (A) Normal K-H (B) HCO<sub>3</sub><sup>−</sup> free K-H (C) Cl<sup>-</sup> free K-H and (D) Cl<sup>-</sup> and HCO<sub>3</sub><sup>−</sup> both free K-H. (E) Comparison of the peak magnitude of <i>I</i><sub>SC</sub> in different bathing solutions induced by FA(200 µM). Values are mean ± SEM (n = 5, ***p<0.001 vs. control).</p
CFD modelling of the thermal degradation of biomass in fluidized beds
No full textPyrolysis is considered as a promising technology of recovering bioenergy from biomass into gas, liquid and solid fuels. A series of works have been carried out previously on the fundamentals and the decomposition mechanism of pyrolysis empirically. Based on these experimental works, numerical approaches are employed to achieve a better understanding of the pyrolysis mechanism or aid the applications in experimental and industrial area.In order to construct a systematic model of the thermochemical processes in biomass pyrolysis in a fluidized bed, the mass and heat transfer processes are investigated by two sub-subjects: modelling of the heat exchange between an immersed tube and a fluidized bed; modelling of mixing-segregation phenomena of binary mixture loaded in a fluidized bed as bed materials. Based on the finished studies, two reacting beds are represented by Eulerian approaches. The fast pyrolysis and catalytic pyrolysis of biomass is modelled by incorporating the corresponding kinetic schemes into the mass and heat transfer processes. The relevant models, coefficients and functions are tested and discussed for the sensitivity and the simulation results show qualitative consistence with the existing experimental works. The general model for thermochemical processes of biomass in the fluidised beds is built up in the present work successfully. The entire structure and methods can be introduced into other applications but not limited to biomass pyrolysis. The further optimization based on this model can be a useful tool on design of a large-scale pyrolyzor.<br/
Dual tumor-targeted poly(lactic-co-glycolic acid)–polyethylene glycol–folic acid nanoparticles: a novel biodegradable nanocarrier for secure and efficient antitumor drug delivery
No full textJia Chen,1,2,* Qi Wu,1,* Li Luo,1 Yi Wang,1 Yuan Zhong,1 Han-Bin Dai,1 Da Sun,1,3 Mao-Ling Luo,4 Wei Wu,1 Gui-Xue Wang1 1Key Laboratory for Biorheological Science and Technology, Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College, Chongqing University, Chongqing, 2Institute of Laboratory Animals, Sichuan Academy of Medical Science, Sichuan Provincial People’s Hospital, Chengdu, 3Institute of Life Sciences, Wenzhou University, Wenzhou, 4School of Medicine, Wuhan University, Wuhan, China *These authors contributed equally to this work Abstract: Further specific target-ability development of biodegradable nanocarriers is extremely important to promote their security and efficiency in antitumor drug-delivery applications. In this study, a facilely prepared poly(lactic-co-glycolic acid) (PLGA)–polyethylene glycol (PEG)–folic acid (FA) copolymer was able to self-assemble into nanoparticles with favorable hydrodynamic diameters of around 100 nm and negative surface charge in aqueous solution, which was expected to enhance intracellular antitumor drug delivery by advanced dual tumor-target effects, ie, enhanced permeability and retention induced the passive target, and FA mediated the positive target. Fluorescence-activated cell-sorting and confocal laser-scanning microscopy results confirmed that doxorubicin (model drug) loaded into PLGA-PEG-FA nanoparticles was able to be delivered efficiently into tumor cells and accumulated at nuclei. In addition, all hemolysis, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, and zebrafish-development experiments demonstrated that PLGA-PEG-FA nanoparticles were biocompatible and secure for biomedical applications, even at high polymer concentration (0.1 mg/mL), both in vitro and in vivo. Therefore, PLGA-PEG-FA nanoparticles provide a feasible controlled-release platform for secure and efficient antitumor drug delivery. Keywords: tumor target, biodegradable nanoparticle, security, efficient, drug delivery, tumor therapy 
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