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Sample records for strongylocentrotus purpuratus shell

  1. New biomarkers of post-settlement growth in the sea urchin Strongylocentrotus purpuratus.

    Science.gov (United States)

    Fadl, Alyaa Elsaid Abdelaziz; Mahfouz, Magdy Elsayed; El-Gamal, Mona Mabrouk Taha; Heyland, Andreas

    2017-10-01

    Some sea urchins, including the purple sea urchin Strongylocentrotus purpuratus, have been successfully used in aquaculture, but their slow growth and late reproduction are challenging to overcome when developing efficient aquaculture production techniques. S. purpuratus develops via an indirect life history that is characterized by a drastic settlement process at the end of a larval period that lasts for several weeks. During this transition, the bilateral larva is transformed into a pentaradial juvenile, which will start feeding and growing in the benthic habitat. Due to predation and other ecological factors, settlement is typically associated with high mortality rates in juvenile populations. Additionally, juveniles require several days to develop a functional mouth and digestive system. During this perimetamorphic period, juveniles use up larval resources until they are capable to digest adult food. Mechanisms underlying the onset of juvenile feeding and metabolism have implications for the recruitment of natural populations as well as aquaculture and are relatively poorly understood in S. purpuratus . The insulin/insulin-like growth factor signalling (IIS)/Target of Rapamycin (TOR) pathway (IIS/TOR) is well conserved among animal phyla and regulates physiological and developmental functions, such as growth, reproduction, aging and nutritional status. We analyzed the expression of FoxO, TOR, and ILPs in post-settlement juveniles in conjunction with their early growth trajectories. We also tested how pre-settlement starvation affected post-settlement expression of IIS. We found that FoxO provides a useful molecular marker in early juveniles as its expression is strongly correlated with juvenile growth. We also found that pre-settlement starvation affects juvenile growth trajectories as well as IIS. Our findings provide preliminary insights into the mechanisms underlying post-settlement growth and metabolism in S. purpuratus . They also have important

  2. New biomarkers of post-settlement growth in the sea urchin Strongylocentrotus purpuratus

    Directory of Open Access Journals (Sweden)

    Alyaa Elsaid Abdelaziz Fadl

    2017-10-01

    Full Text Available Some sea urchins, including the purple sea urchin Strongylocentrotus purpuratus, have been successfully used in aquaculture, but their slow growth and late reproduction are challenging to overcome when developing efficient aquaculture production techniques. S. purpuratus develops via an indirect life history that is characterized by a drastic settlement process at the end of a larval period that lasts for several weeks. During this transition, the bilateral larva is transformed into a pentaradial juvenile, which will start feeding and growing in the benthic habitat. Due to predation and other ecological factors, settlement is typically associated with high mortality rates in juvenile populations. Additionally, juveniles require several days to develop a functional mouth and digestive system. During this perimetamorphic period, juveniles use up larval resources until they are capable to digest adult food. Mechanisms underlying the onset of juvenile feeding and metabolism have implications for the recruitment of natural populations as well as aquaculture and are relatively poorly understood in S. purpuratus. The insulin/insulin-like growth factor signalling (IIS/Target of Rapamycin (TOR pathway (IIS/TOR is well conserved among animal phyla and regulates physiological and developmental functions, such as growth, reproduction, aging and nutritional status. We analyzed the expression of FoxO, TOR, and ILPs in post-settlement juveniles in conjunction with their early growth trajectories. We also tested how pre-settlement starvation affected post-settlement expression of IIS. We found that FoxO provides a useful molecular marker in early juveniles as its expression is strongly correlated with juvenile growth. We also found that pre-settlement starvation affects juvenile growth trajectories as well as IIS. Our findings provide preliminary insights into the mechanisms underlying post-settlement growth and metabolism in S. purpuratus. They also have

  3. Ocean acidification research in the 'post-genomic' era: Roadmaps from the purple sea urchin Strongylocentrotus purpuratus.

    Science.gov (United States)

    Evans, Tyler G; Padilla-Gamiño, Jacqueline L; Kelly, Morgan W; Pespeni, Melissa H; Chan, Francis; Menge, Bruce A; Gaylord, Brian; Hill, Tessa M; Russell, Ann D; Palumbi, Stephen R; Sanford, Eric; Hofmann, Gretchen E

    2015-07-01

    Advances in nucleic acid sequencing technology are removing obstacles that historically prevented use of genomics within ocean change biology. As one of the first marine calcifiers to have its genome sequenced, purple sea urchins (Strongylocentrotus purpuratus) have been the subject of early research exploring genomic responses to ocean acidification, work that points to future experiments and illustrates the value of expanding genomic resources to other marine organisms in this new 'post-genomic' era. This review presents case studies of S. purpuratus demonstrating the ability of genomic experiments to address major knowledge gaps within ocean acidification. Ocean acidification research has focused largely on species vulnerability, and studies exploring mechanistic bases of tolerance toward low pH seawater are comparatively few. Transcriptomic responses to high pCO₂ seawater in a population of urchins already encountering low pH conditions have cast light on traits required for success in future oceans. Secondly, there is relatively little information on whether marine organisms possess the capacity to adapt to oceans progressively decreasing in pH. Genomics offers powerful methods to investigate evolutionary responses to ocean acidification and recent work in S. purpuratus has identified genes under selection in acidified seawater. Finally, relatively few ocean acidification experiments investigate how shifts in seawater pH combine with other environmental factors to influence organism performance. In S. purpuratus, transcriptomics has provided insight into physiological responses of urchins exposed simultaneously to warmer and more acidic seawater. Collectively, these data support that similar breakthroughs will occur as genomic resources are developed for other marine species. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Histamine is a modulator of metamorphic competence in Strongylocentrotus purpuratus (Echinodermata: Echinoidea

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    Sutherby Josh

    2012-04-01

    Full Text Available Abstract Background A metamorphic life-history is present in the majority of animal phyla. This developmental mode is particularly prominent among marine invertebrates with a bentho-planktonic life cycle, where a pelagic larval form transforms into a benthic adult. Metamorphic competence (the stage at which a larva is capable to undergo the metamorphic transformation and settlement is an important adaptation both ecologically and physiologically. The competence period maintains the larval state until suitable settlement sites are encountered, at which point the larvae settle in response to settlement cues. The mechanistic basis for metamorphosis (the morphogenetic transition from a larva to a juvenile including settlement, i.e. the molecular and cellular processes underlying metamorphosis in marine invertebrate species, is poorly understood. Histamine (HA, a neurotransmitter used for various physiological and developmental functions among animals, has a critical role in sea urchin fertilization and in the induction of metamorphosis. Here we test the premise that HA functions as a developmental modulator of metamorphic competence in the sea urchin Strongylocentrotus purpuratus. Results Our results provide strong evidence that HA leads to the acquisition of metamorphic competence in S. purpuratus larvae. Pharmacological analysis of several HA receptor antagonists and an inhibitor of HA synthesis indicates a function of HA in metamorphic competence as well as programmed cell death (PCD during arm retraction. Furthermore we identified an extensive network of histaminergic neurons in pre-metamorphic and metamorphically competent larvae. Analysis of this network throughout larval development indicates that the maturation of specific neuronal clusters correlates with the acquisition of metamorphic competence. Moreover, histamine receptor antagonist treatment leads to the induction of caspase mediated apoptosis in competent larvae. Conclusions We

  5. Non-directional photoreceptors in the pluteus of Strongylocentrotus purpuratus

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    Alberto Valero-Gracia

    2016-11-01

    Full Text Available In comparison to complex visual systems, non-directional photoreception – the most primitive form of biological photodetection – has been poorly investigated, although it is essential to many biological processes such as circadian and seasonal rhythms. Here we describe the spatiotemporal expression pattern of the major molecular actors mediating light reception – opsins – localized in the Strongylocentrotus purpuratus larva. In contrast to other zooplanktonic larvae, the echinopluteus lacks photoreceptor cells with observable shading pigments involved in directional visual tasks. Nonetheless, the echinopluteus expresses two distinct classes of opsins: a Go-opsin and a rhabdomeric opsin. The Go-opsin, Sp-opsin3.2, is detectable at early (3 days post fertilization and four armed pluteus stages (4 days post fertilization in two cells that flank the apical organ. To rule out the presence of shading pigments involved in directional photoreception, we used electron microscopy to explore the expression domain of Go-opsin Sp-opsin3.2 positive cells. The rhabdomeric opsin Sp-Opsin4 expression is detectable in clusters of cells located around the primary podia at the five-fold ectoderm pentagonal disc stage (day 18-21 and thereafter, thus indicating that Sp-Opsin4 may not be involved in the photoreception mechanism of the larva, but only of the juvenile. We discuss the putative function of the relevant cells in their neural context, and propose a model for understanding simple photodetection in marine larvae.

  6. Characterization of the proteins comprising the integral matrix of Strongylocentrotus purpuratus embryonic spicules

    Science.gov (United States)

    Killian, C. E.; Wilt, F. H.

    1996-01-01

    In the present study, we enumerate and characterize the proteins that comprise the integral spicule matrix of the Strongylocentrotus purpuratus embryo. Two-dimensional gel electrophoresis of [35S]methionine radiolabeled spicule matrix proteins reveals that there are 12 strongly radiolabeled spicule matrix proteins and approximately three dozen less strongly radiolabeled spicule matrix proteins. The majority of the proteins have acidic isoelectric points; however, there are several spicule matrix proteins that have more alkaline isoelectric points. Western blotting analysis indicates that SM50 is the spicule matrix protein with the most alkaline isoelectric point. In addition, two distinct SM30 proteins are identified in embryonic spicules, and they have apparent molecular masses of approximately 43 and 46 kDa. Comparisons between embryonic spicule matrix proteins and adult spine integral matrix proteins suggest that the embryonic 43-kDa SM30 protein is an embryonic isoform of SM30. An adult 49-kDa spine matrix protein is also identified as a possible adult isoform of SM30. Analysis of the SM30 amino acid sequences indicates that a portion of SM30 proteins is very similar to the carbohydrate recognition domain of C-type lectin proteins.

  7. Engineering Pichia pastoris for Efficient Production of a Novel Bifunctional Strongylocentrotus purpuratus Invertebrate-Type Lysozyme.

    Science.gov (United States)

    Huang, Peng; Shi, Jinlei; Sun, Qingwen; Dong, Xianping; Zhang, Ning

    2018-04-13

    Lysozymes are known as ubiquitously distributed immune effectors with hydrolytic activity against peptidoglycan, the major bacterial cell wall polymer, to trigger cell lysis. In the present study, the full-length cDNA sequence of a novel sea urchin Strongylocentrotus purpuratus invertebrate-type lysozyme (sp-iLys) was synthesized according to the codon usage bias of Pichia pastoris and was cloned into a constitutive expression plasmid pPIC9K. The resulting plasmid, pPIC9K-sp-iLys, was integrated into the genome of P. pastoris strain GS115. The bioactive recombinant sp-iLys was successfully secreted into the culture broth by positive transformants. The highest lytic activity of 960 U/mL of culture supernatant was reached in fed-batch fermentation. Using chitin affinity chromatography and gel-filtration chromatography, recombinant sp-iLys was produced with a yield of 94.5 mg/L and purity of > 99%. Recombinant sp-iLys reached its peak lytic activity of 8560 U/mg at pH 6.0 and 30 °C and showed antimicrobial activities against Gram-negative bacteria (Vibrio vulnificus, Vibrio parahemolyticus, and Aeromonas hydrophila) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). In addition, recombinant sp-iLys displayed isopeptidase activity which reached the peak at pH 7.5 and 37 °C with the presence of 0.05 M Na + . In conclusion, this report describes the heterologous expression of recombinant sp-iLys in P. pastoris on a preparative-scale, which possesses lytic activity and isopeptidase activity. This suggests that sp-iLys might play an important role in the innate immunity of S. purpuratus.

  8. The sea urchin (Strongylocentrotus purpuratus test and spine proteomes

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    Mann Karlheinz

    2008-08-01

    Full Text Available Abstract Background The organic matrix of biominerals plays an important role in biomineral formation and in determining biomineral properties. However, most components of biomineral matrices remain unknown at present. In sea urchin, which is an important model organism for developmental biology and biomineralization, only few matrix components have been identified and characterized at the protein level. The recent publication of the Strongylocentrotus purpuratus genome sequence rendered possible not only the identification of possible matrix proteins at the gene level, but also the direct identification of proteins contained in matrices of skeletal elements by in-depth, high-accuracy, proteomic analysis. Results We identified 110 proteins as components of sea urchin test and spine organic matrix. Fourty of these proteins occurred in both compartments while others were unique to their respective compartment. More than 95% of the proteins were detected in sea urchin skeletal matrices for the first time. The most abundant protein in both matrices was the previously characterized spicule matrix protein SM50, but at least eight other members of this group, many of them only known as conceptual translation products previously, were identified by mass spectrometric sequence analysis of peptides derived from in vitro matrix degradation. The matrices also contained proteins implicated in biomineralization processes previously by inhibition studies using antibodies or specific enzyme inhibitors, such as matrix metalloproteases and members of the mesenchyme-specific MSP130 family. Other components were carbonic anhydrase, collagens, echinonectin, a α2-macroglobulin-like protein and several proteins containing scavenger receptor cysteine-rich domains. A few possible signal transduction pathway components, such as GTP-binding proteins, a semaphorin and a possible tyrosine kinase were also identified. Conclusion This report presents the most comprehensive

  9. Effects of an oil production effluent on gametogenesis and gamete performance in the purple sea urchin (Strongylocentrotus purpuratus Stimpson)

    International Nuclear Information System (INIS)

    Krause, P.R.

    1994-01-01

    Adult organisms subjected to chronic discharges from a point source of pollution may exhibit several sublethal responses. One such response is the impairment of gamete production. This may be expressed in the amount and/or quality of gametes produced by adults. In this study the effects of chronic exposure to produced water (an oil production effluent) on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus Stimpson) were examined using an in situ caging experiment. Adult purple sea urchins were kept in benthic cages arrayed down-field from a discharging diffuser at 13 sites, with distances ranging from 5 to 1,000 m. Cage exposures were maintained in the field for eight weeks, and each cage held 25 animals. Gametogenesis was examined for each sex by comparing a size-independent measure of relative gonads ass as determined by analysis of covariance. Results showed that there was a significant negative relationship between these estimates of relative gonad mass and distance from the outfall for both sexes, indicating that sea urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetics bioassay that held the concentration of eggs constant and varied the amount of sperm added. The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a model of fertilizability showed a positive relationship with distance away from the outfall. These findings indicate that although adult sea urchins exposed to a produced water outfall exhibit larger gonads, they suffer a marked decrease in a gamete performance

  10. A pancreatic exocrine-like cell regulatory circuit operating in the upper stomach of the sea urchin Strongylocentrotus purpuratus larva.

    Science.gov (United States)

    Perillo, Margherita; Wang, Yue Julia; Leach, Steven D; Arnone, Maria Ina

    2016-05-26

    Digestive cells are present in all metazoans and provide the energy necessary for the whole organism. Pancreatic exocrine cells are a unique vertebrate cell type involved in extracellular digestion of a wide range of nutrients. Although the organization and regulation of this cell type is intensively studied in vertebrates, its evolutionary history is still unknown. In order to understand which are the elements that define the pancreatic exocrine phenotype, we have analyzed the expression of genes that contribute to specification and function of this cell-type in an early branching deuterostome, the sea urchin Strongylocentrotus purpuratus. We defined the spatial and temporal expression of sea urchin orthologs of pancreatic exocrine genes and described a unique population of cells clustered in the upper stomach of the sea urchin embryo where exocrine markers are co-expressed. We used a combination of perturbation analysis, drug and feeding experiments and found that in these cells of the sea urchin embryo gene expression and gene regulatory interactions resemble that of bona fide pancreatic exocrine cells. We show that the sea urchin Ptf1a, a key transcriptional activator of digestive enzymes in pancreatic exocrine cells, can substitute for its vertebrate ortholog in activating downstream genes. Collectively, our study is the first to show with molecular tools that defining features of a vertebrate cell-type, the pancreatic exocrine cell, are shared by a non-vertebrate deuterostome. Our results indicate that the functional cell-type unit of the vertebrate pancreas may evolutionarily predate the emergence of the pancreas as a discrete organ. From an evolutionary perspective, these results encourage to further explore the homologs of other vertebrate cell-types in traditional or newly emerging deuterostome systems.

  11. Characterization and expression analysis of Galnts in developing Strongylocentrotus purpuratus embryos.

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    Amber L Famiglietti

    Full Text Available Mucin-type O-glycosylation is a ubiquitous posttranslational modification in which N-Acetylgalactosamine (GalNAc is added to the hydroxyl group of select serine or threonine residues of a protein by the family of UDP-GalNAc:Polypeptide N-Acetylgalactosaminyltransferases (GalNAc-Ts; EC 2.4.1.41. Previous studies demonstrate that O-glycosylation plays essential roles in protein function, cell-cell interactions, cell polarity and differentiation in developing mouse and Drosophila embryos. Although this type of protein modification is highly conserved among higher eukaryotes, little is known about this family of enzymes in echinoderms, basal deuterostome relatives of the chordates. To investigate the potential role of GalNAc-Ts in echinoderms, we have begun the characterization of this enzyme family in the purple sea urchin, S. purpuratus. We have fully or partially cloned a total of 13 genes (SpGalnts encoding putative sea urchin SpGalNAc-Ts, and have confirmed enzymatic activity of five recombinant proteins. Amino acid alignments revealed high sequence similarity among sea urchin and mammalian glycosyltransferases, suggesting the presence of putative orthologues. Structural models underscored these similarities and helped reconcile some of the substrate preferences observed. Temporal and spatial expression of SpGalnt transcripts, was studied by whole-mount in situ hybridization. We found that many of these genes are transcribed early in developing embryos, often with restricted expression to the endomesodermal region. Multicolor fluorescent in situ hybridization (FISH demonstrated that transcripts encoding SpGalnt7-2 co-localized with both Endo16 (a gene expressed in the endoderm, and Gcm (a gene expressed in secondary mesenchyme cells at the early blastula stage, 20 hours post fertilization (hpf. At late blastula stage (28 hpf, SpGalnt7-2 message co-expresses with Gcm, suggesting that it may play a role in secondary mesenchyme development. We

  12. Effects of increased pCO2 and geographic origin on purple sea urchin (Strongylocentrotus purpuratus) calcite elemental composition

    Science.gov (United States)

    LaVigne, M.; Hill, T. M.; Sanford, E.; Gaylord, B.; Russell, A. D.; Lenz, E. A.; Hosfelt, J. D.; Young, M. K.

    2012-12-01

    Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (such as Mg and Sr) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore the effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low to high magnesium calcites. Mg/Ca and Sr/Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions along the US west coast (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg/Ca and Sr/Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg/Ca or Sr/Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 ppm; pH = 8.02 ± 0.03 1 SD; Ωcalcite = 3.3 ± 0.2 1 SD). However, when reared under elevated CO2 (900 ppm; pH = 7.72 ± 0.03; Ωcalcite = 1.8 ± 0.1), skeletal Sr/Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated CO2 (Sr/Ca = 2

  13. Effects of five southern California macroalgal diets on consumption, growth, and gonad weight, in the purple sea urchin Strongylocentrotus purpuratus

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    Matthew C. Foster

    2015-01-01

    Full Text Available Consumer growth and reproductive capacity are direct functions of diet. Strongylocentrotid sea urchins, the dominant herbivores in California kelp forests, strongly prefer giant kelp (Macrocystis pyrifera, but are highly catholic in their ability to consume other species. The biomass of Macrocystis fluctuates greatly in space and time, and the extent to which urchins can use alternate species of algae or a mixed diet of multiple algal species to maintain fitness when giant kelp is unavailable is unknown. We experimentally examined the effects of single and mixed species diets on consumption, growth and gonad weight in the purple sea urchin Strongylocentrotus purpuratus. Urchins were fed single species diets consisting of one of four common species of macroalgae (the kelps Macrocystis pyrifera and Pterygophora californica, and the red algae Chondracanthus corymbiferus and Rhodymenia californica (hereafter referred to by genus or a mixed diet containing all four species ad libitum over a 13-week period in a controlled laboratory setting. Urchins fed Chondracanthus, Macrocystis and a mixed diet showed the highest growth (in terms of test diameter, wet weight and jaw length and gonad weight, while urchins fed Pterygophora and Rhodymenia showed the lowest. Urchins consumed their preferred food, Macrocystis, at the highest rate when offered a mixture, but consumed Chondracanthus or Macrocystis at similar rates when the two algae were offered alone. The differences in urchin feeding behavior and growth observed between these diet types suggest the relative availability of the algae tested here could affect urchin populations and their interactions with the algal assemblage. The fact that the performance of urchins fed Chondracanthus was similar or higher than those fed the preferred Macrocystis suggests that the availability of the former could could sustain growth and reproduction of purple sea urchins during times of low Macrocystis abundance as is

  14. NCBI nr-aa BLAST: CBRC-DNOV-01-0174 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DNOV-01-0174 ref|XP_786035.2| PREDICTED: similar to autism-related protein 1 [...Strongylocentrotus purpuratus] ref|XP_001191209.1| PREDICTED: similar to autism-related protein 1 [Strongylocentrotus purpuratus] XP_786035.2 2.3 34% ...

  15. Geographical variation of shell thickness in the mussel Perumytilus purpuratus along the southeast Pacific coast.

    Science.gov (United States)

    Briones, Carolina; Rivadeneira, Marcelo M; Fernández, Miriam; Guiñez, Ricardo

    2014-12-01

    At broad geographical scales, the variation in bivalve shell thickness can be modulated by environmental factors that vary with latitude, such as sea surface temperature (SST), seawater pH, or calcium carbonate availability. Mussels usually form multilayered beds, and shell thickness is also expected to be affected by density and layering due to intraspecific competition. In this work, we explored the geographical variation of shell thickness in the intertidal mussel Perumytilus purpuratus between 18° and 42°S along the southeastern Pacific coast. We tested the hypothesis that there was a positive relationship between shell thickness and SST, and then we explored other variables that could have an effect on thickness, such as density, number of layers, and others environmental variables (pH and calcite concentration). The expected positive linear relationship between shell thickness and sea surface temperature was not found, but when the other population variables were included in the analysis, an unexpected inverse SST-thickness relationships appeared as significant, probably because this species could be adapted to colder and more acid seawater as are those of the tips of South America. Thickness was also negatively affected by density, which was expected for a gregarious species showing high intraspecific competition. Finally, our results highlight the importance of including density and crowding effects when macroscale patterns are explored, particularly in gregarious species, since these patterns could also be modulated by density-dependent processes, which might then override latitudinal trends of shell thickness when they are not included in the analyses. © 2014 Marine Biological Laboratory.

  16. NCBI nr-aa BLAST: CBRC-CBRE-01-0130 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-CBRE-01-0130 ref|XP_782524.1| PREDICTED: similar to Slc40a1-prov protein [Stro...ngylocentrotus purpuratus] ref|XP_001190795.1| PREDICTED: similar to Slc40a1-prov protein [Strongylocentrotus purpuratus] XP_782524.1 4e-26 30% ...

  17. The elemental composition of purple sea urchin (Strongylocentrotus purpuratus) calcite and potential effects of pCO2 during early life stages

    Science.gov (United States)

    LaVigne, M.; Hill, T. M.; Sanford, E.; Gaylord, B.; Russell, A. D.; Lenz, E. A.; Hosfelt, J. D.; Young, M. K.

    2013-06-01

    Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (e.g. magnesium) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low- to high-Mg calcites. Mg / Ca and Sr / Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions spanning a range of carbonate chemistry conditions (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg / Ca and Sr / Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg / Ca or Sr / Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 μatm; pHT = 8.02 ± 0.03 1 SD; Ωcalcite = 3.3 ± 0.2 1 SD). However, when reared under elevated pCO2 (900 μatm; pHT = 7.73 ± 0.03; Ωcalcite = 1.8 ± 0.1), skeletal Sr / Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr

  18. The elemental composition of purple sea urchin (Strongylocentrotus purpuratus calcite and potential effects of pCO2 during early life stages

    Directory of Open Access Journals (Sweden)

    M. LaVigne

    2013-06-01

    Full Text Available Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (e.g. magnesium into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2 on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus. We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low- to high-Mg calcites. Mg / Ca and Sr / Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions spanning a range of carbonate chemistry conditions (Oregon, Northern California, Central California, and Southern California. Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg / Ca and Sr / Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg / Ca or Sr / Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 μatm; pHT = 8.02 ± 0.03 1 SD; Ωcalcite = 3.3 ± 0.2 1 SD. However, when reared under elevated pCO2 (900 μatm; pHT = 7.73 ± 0.03; Ωcalcite = 1.8 ± 0.1, skeletal Sr / Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California did not exhibit differences in Mg or Sr

  19. Asociación del color de la concha de reproductores de Argopecten purpuratus (Lamarck, 1819 con la supervivencia, crecimiento y desarrollo larval de sus progenies Association between shell color of breeds (Lamarck, 1819 and the survival, growth and larval development of their progenies

    Directory of Open Access Journals (Sweden)

    Ricardo M García

    2012-07-01

    Full Text Available Las conchas de moluscos bivalvos marinos son extremadamente diversas en sus patrones de pigmentación y riqueza de colores. Tal diversidad se debe a factores ambientales y genéticos. En bivalvos marinos adultos, individuos con coloraciones de concha poco comunes en las poblaciones silvestres suelen presentar tasas de crecimiento y supervivencia menores que aquellos con colores de concha más frecuentes. Conociendo que la variación del color de la concha en Argopecten purpuratus está bajo control genético, en este trabajo se pone a prueba la hipótesis de que los loci responsables de dicha variación pueden afectar el crecimiento, la supervivencia y la tasa de desarrollo de las larvas de esta especie. Se estimó la supervivencia y el crecimiento en progenies de cruzamientos dirigidos entre individuos de A. purpuratus con colores de concha blanco, naranja y marrón, y se verificó la existencia de diferencias en las tasas de desarrollo. El crecimiento de las larvas producidas en cruzamientos que incluyeron individuos marrones o blancos con naranja no mostraron diferencias entre sí. En cambio, las progenies producto de autofecundaciones de individuos naranja y blancos presentaron tasas de crecimiento significativamente menores que las anteriores y distintas entre sí. Las tasas de desarrollo y de supervivencia, en cambio, no mostraron diferencias entre las progenies de los distintos tipos de cruzamientos. Los resultados sugieren que los genes que controlan la variación del color en las conchas de juveniles y adultos de A. purpuratus afectarían la tasa de crecimiento de sus larvas, pero no la tasa de desarrollo ni su supervivencia.Marine bivalve mollusks are extremely diverse in shell color and pigmentation patterns. Such diversity is affected by environmental and genetic factors. Some evidences in adult marine bivalves shows that individuals with low-frequency shell colors have lower growth rates and/or higher mortalities than those with the

  20. Gene : CBRC-CJAC-01-0267 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available ein [Strongylocentrotus purpuratus] 6e-23 26% MRHRDAAGDRRHKLQPGAGRAIGQSACVGPGPSTTPHADSPILLCPSTTPHADCPILLRLSTTPNADCPILLLCPSTTPHADCP...ILLYPSNTPHADCPILLCPSTTPNADCPILLCPSTTPHADCPILLCPSTTPHADCPILFLCPSTTPHADCPSLLYPSNTPHADC...PILLCPSTTPSADCPILLCPSTTPHGDCPILCPSTTPHADCPILLCPCTTPHADCPILLCPSTTSHADCPVLLCPSTXXXXXX

  1. Gene : CBRC-CJAC-01-1131 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available : similar to beta-1,3-galactosyltransferase 6 [Strongylocentrotus purpuratus] 2e-28 29% MTITIIIISPSLSPSSSSLSPSSPSPSS...LSHHHYHHHHHHYPHHHHHNHHYLTIIITIIIIIPIITITIIIISPSLSPSSSSLSPSSPSLSSLSHHCYHHH...HHHHLTIVITIIIIIPIITITIIIISPSLSPSSLSLSPSSPSPSSLSHHHYHHHHYYPHHHHHHYHYLTIVITIIITSLSLSPSSLSLSPSSPSPSSLSHHHYHHHHY...LTVVITIIIIIIPIITITIIIISSPSPSSLSHHHHHHHYLTVIITIIIIIIPIITITITIIIINPIITITIIIITTVVIRIIIIITIIINISTITTAINTIITISVIAIITITNIVTIISISTIAIITIITITDVDNSFYRKKKGKMLRVT ...

  2. Dicty_cDB: Contig-U01139-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 179314 ) Strongylocentrotus purpuratus clone R3-1102P16, W... 32 6.6 5 ( FG289388 ) 1108793297216 New World ...Screwworm Egg 9261 ESTs C... 38 6.9 2 ( FG286433 ) 1108770714983 New World Screww

  3. Effects of produced water on gametogenesis and gamete performance in the purple sea urchin (Stronglyocentrotus purpuratus)

    International Nuclear Information System (INIS)

    Krause, P.R.

    1993-01-01

    The author examined the effects of a chronic exposure to produced water (an oil production effluent) discharge on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus) using an in situ caging experiment. Adult purple urchins were kept in benthic cages arrayed down-field from a discharging diffuser at 13 sites with distances ranging from 5m to 1,000m. Cage exposures were maintained in the field for eight weeks and each cage held 25 urchins. Gametogenesis was examined for each sex by comparing a size-independent measure of gonad mass as determined by analysis of covariance. The author found that there was a significant negative relationship between gonad mass and cage distance for both sexes, indicating that urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetic bioassay that holds the concentration of eggs constant and varies the amount of sperm added. The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a kinetics model. Significant differences were found in the fertilizability of eggs between cages. This showed a positive relationship with distance away from the outfall. The findings indicate that while adult urchins exposed to a produced water outfall produced larger gonads, they suffered a marked decreases in gamete performance

  4. Dicty_cDB: Contig-U14349-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 36 0.10 2 ( FE846078 ) CAFI539.rev CAFI Pichia stipitis aerobic dextrose... 38 0.11 2 ( FE846079 ) CAFI539.f...wd CAFI Pichia stipitis aerobic dextrose... 38 0.11 2 ( AC176598 ) Strongylocentrotus purpuratus clone R3-30

  5. Base excision DNA repair in the embryonic development of the sea urchin, Strongylocentrotus intermedius.

    Science.gov (United States)

    Torgasheva, Natalya A; Menzorova, Natalya I; Sibirtsev, Yurii T; Rasskazov, Valery A; Zharkov, Dmitry O; Nevinsky, Georgy A

    2016-06-21

    In actively proliferating cells, such as the cells of the developing embryo, DNA repair is crucial for preventing the accumulation of mutations and synchronizing cell division. Sea urchin embryo growth was analyzed and extracts were prepared. The relative activity of DNA polymerase, apurinic/apyrimidinic (AP) endonuclease, uracil-DNA glycosylase, 8-oxoguanine-DNA glycosylase, and other glycosylases was analyzed using specific oligonucleotide substrates of these enzymes; the reaction products were resolved by denaturing 20% polyacrylamide gel electrophoresis. We have characterized the profile of several key base excision repair activities in the developing embryos (2 blastomers to mid-pluteus) of the grey sea urchin, Strongylocentrotus intermedius. The uracil-DNA glycosylase specific activity sharply increased after blastula hatching, whereas the specific activity of 8-oxoguanine-DNA glycosylase steadily decreased over the course of the development. The AP-endonuclease activity gradually increased but dropped at the last sampled stage (mid-pluteus 2). The DNA polymerase activity was high at the first cleavage division and then quickly decreased, showing a transient peak at blastula hatching. It seems that the developing sea urchin embryo encounters different DNA-damaging factors early in development within the protective envelope and later as a free-floating larva, with hatching necessitating adaptation to the shift in genotoxic stress conditions. No correlation was observed between the dynamics of the enzyme activities and published gene expression data from developing congeneric species, S. purpuratus. The results suggest that base excision repair enzymes may be regulated in the sea urchin embryos at the level of covalent modification or protein stability.

  6. EST Table: FS927325 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available ar to Restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Strongylocentrotus pu...rpuratus] ref|XP_001183478.1| PREDICTED: similar to Restin (Reed-Steinberg cell-expressed intermediate filam...CTED: similar to restin (Reed-Steinberg cell-expressed intermediate filament-associated protein) [Tribolium castaneum] CK533543 fwgP ...

  7. Dicty_cDB: Contig-U01461-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 38 0.002 2 ( FK759294 ) av02122h06r1.1 Symbiotic sea anemone (Anemonia vi... 40 0.002 3 ( AC178264 ) Strongy... ) Strongylocentrotus purpuratus clone R3-14I24, WOR... 44 0.014 6 ( FK730160 ) av02050j21r1.1 Symbiotic sea

  8. The offline combination of thin-layer chromatography and high-performance liquid chromatography with diode array detection and micrOTOF-Q mass spectrometry for the separation and identification of spinochromes from sea urchin (Strongylocentrotus droebachiensis) shells.

    Science.gov (United States)

    Shikov, Alexander N; Ossipov, Vladimir I; Martiskainen, Olli; Pozharitskaya, Olga N; Ivanova, Svetlana A; Makarov, Valery G

    2011-12-16

    Thin-layer chromatography (TLC) with off-line high-performance liquid chromatography coupled to diode array detection and micrOTOF-Q mass spectrometry (HPLC-DAD-MS) resulted in the successful fractionation, separation and identification of spinochrome pigments from sea urchin (Strongylocentrotus droebachiensis) shells. Two fractions of pigments were separated by TLC and eluted with methanol using a TLC-MS interface. HPLC-DAD-MS analysis of the fractions indicated the presence of six sea urchin pigments: spinochrome monomers B and D, three spinochrome dimers (anhydroethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin) and its isomer and ethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin)), and one pigment that was preliminary identified as a spinochrome dimer with the structural formula C(22)H(16)O(16). Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Occurrence of psilocybin, psilocin and baeocystin in Gymnopilus purpuratus

    NARCIS (Netherlands)

    Gartz, J.

    1989-01-01

    Analysis of Gymnopilus purpuratus from two localities in the G.D.R. revealed the presence of psilocybin, psilocin and low concentrations of baeocystin. Psilocybin levels varied from 0.07 % up to 0.33 % of dry weight of the bluing basidiocarps. The psilocin content was high and reached 0.31 % of dry

  10. Dicty_cDB: Contig-U05011-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 4 1.0 3 ( FG289817 ) 1108793307980 New World Screwworm Egg 9261 ESTs C... 38 1.3 3 ( AC176252 ) Strongylocen...trotus purpuratus clone R3-3060I22, W... 40 1.3 4 ( FG290522 ) 1108793323765 New World... Screwworm Egg 9261 ESTs C... 38 1.4 3 ( FG286635 ) 1108770723708 New World Screwworm Egg 9261 ESTs C..

  11. The 3’UTR of Nanos2 directs enrichment in the germ cell lineage of the sea urchin

    OpenAIRE

    Oulhen, Nathalie; Yoshida, Takaya; Yajima, Mamiko; Song, Jia; Sakuma, Tetsushi; Sakamoto, Naoaki; Yamamoto, Takashi; Wessel, Gary M.

    2013-01-01

    Nanos is a translational regulator required for the survival and maintenance of primordial germ cells during embryogenesis. Three nanos homologs are present in the genome of the sea urchin Strongylocentrotus purpuratus (Sp), and each nanos mRNA accumulates specifically in the small micromere (sMic) lineage. We found that a highly conserved element in the 3’ UTR of nanos2 is sufficient for reporter expression selectively in the sMic lineage: microinjection into a Sp fertilized egg of an RNA th...

  12. Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification

    KAUST Repository

    Ramajo, Laura; Marbà , Nú ria; Prado, Luis; Peron, Sophie; Lardies, Marco A.; Rodriguez-Navarro, Alejandro; Vargas, Cristian A.; Lagos, Nelson A.; Duarte, Carlos M.

    2015-01-01

    Future ocean acidification (OA) will affect physiological traits of marine species, with calcifying species being particularly vulnerable. As OA entails high energy demands, particularly during the rapid juvenile growth phase, food supply may play a key role in the response of marine organisms to OA. We experimentally evaluated the role of food supply in modulating physiological responses and biomineralization processes in juveniles of the Chilean scallop, Argopecten purpuratus, that were exposed to control (pH ~ 8.0) and low pH (pH ~ 7.6) conditions using three food supply treatments (high, intermediate, and low). We found that pH and food levels had additive effects on the physiological response of the juvenile scallops. Metabolic rates, shell growth, net calcification, and ingestion rates increased significantly at low pH conditions, independent of food. These physiological responses increased significantly in organisms exposed to intermediate and high levels of food supply. Hence, food supply seems to play a major role modulating organismal response by providing the energetic means to bolster the physiological response of OA stress. On the contrary, the relative expression of chitin synthase, a functional molecule for biomineralization, increased significantly in scallops exposed to low food supply and low pH, which resulted in a thicker periostracum enriched with chitin polysaccharides. Under reduced food and low pH conditions, the adaptive organismal response was to trade-off growth for the expression of biomineralization molecules and altering of the organic composition of shell periostracum, suggesting that the future performance of these calcifiers will depend on the trajectories of both OA and food supply. Thus, incorporating a suite of traits and multiple stressors in future studies of the adaptive organismal response may provide key insights on OA impacts on marine calcifiers.

  13. Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification

    KAUST Repository

    Ramajo, Laura

    2015-12-08

    Future ocean acidification (OA) will affect physiological traits of marine species, with calcifying species being particularly vulnerable. As OA entails high energy demands, particularly during the rapid juvenile growth phase, food supply may play a key role in the response of marine organisms to OA. We experimentally evaluated the role of food supply in modulating physiological responses and biomineralization processes in juveniles of the Chilean scallop, Argopecten purpuratus, that were exposed to control (pH ~ 8.0) and low pH (pH ~ 7.6) conditions using three food supply treatments (high, intermediate, and low). We found that pH and food levels had additive effects on the physiological response of the juvenile scallops. Metabolic rates, shell growth, net calcification, and ingestion rates increased significantly at low pH conditions, independent of food. These physiological responses increased significantly in organisms exposed to intermediate and high levels of food supply. Hence, food supply seems to play a major role modulating organismal response by providing the energetic means to bolster the physiological response of OA stress. On the contrary, the relative expression of chitin synthase, a functional molecule for biomineralization, increased significantly in scallops exposed to low food supply and low pH, which resulted in a thicker periostracum enriched with chitin polysaccharides. Under reduced food and low pH conditions, the adaptive organismal response was to trade-off growth for the expression of biomineralization molecules and altering of the organic composition of shell periostracum, suggesting that the future performance of these calcifiers will depend on the trajectories of both OA and food supply. Thus, incorporating a suite of traits and multiple stressors in future studies of the adaptive organismal response may provide key insights on OA impacts on marine calcifiers.

  14. Effects of long-term elevated temperature on covering, sheltering and righting behaviors of the sea urchin Strongylocentrotus intermedius

    Science.gov (United States)

    Zhang, Lisheng; Zhang, Lingling; Shi, Dongtao; Wei, Jing; Chang, Yaqing

    2017-01-01

    Increases in ocean temperature due to climate change are predicted to change the behaviors of marine invertebrates. Altered behaviors of keystone ecosystem engineers such as echinoderms will have consequences for the fitness of individuals, which are expected to flow on to the local ecosystem. Relatively few studies have investigated the behavioral responses of echinoderms to long-term elevated temperature. We investigated the effects of exposure to long-term (∼31 weeks) elevated temperature (∼3 °C above the ambient water temperature) on covering, sheltering and righting behaviors of the sea urchin Strongylocentrotus intermedius. Long-term elevated temperature showed different effects on the three behaviors. It significantly decreased covering behavior, including both covering behavior reaction (time to first covering) and ability (number of covered sea urchins and number of shells used for covering). Conversely, exposure to long-term elevated temperature significantly increased sheltering behavior. Righting response in S. intermedius was not significantly different between temperature treatments. The results provide new information into behavioral responses of echinoderms to ocean warming. PMID:28348933

  15. Cell surface of sea urchin micromeres and primary mesenchyme

    International Nuclear Information System (INIS)

    DeSimone, D.W.

    1985-01-01

    The cell surface and extracellular matrix (ECM) of the sea urchin embryo were studied during the early morphogenetic events involved in the differentiation of the micromere cell lineage. Sixteen-cell and early cleavage stage blastomeres were isolated and the protein composition of their cell surfaces examined by 125 I-labelling followed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Micromere-specific cell surface proteins are reported for Arbacia punctulata, Strongylocentrotus droebachiensis, and Strongylocentrotus purpuratus. Cell surface glycoproteins were characterized on the basis of lectin binding specificity with a novel lectin affinity transfer technique. Using this procedure, cell-type specific surface proteins, which are also lectin-binding specific, can be detected. In addition, fluorescein conjugated lectins were microinjected into the blastocoels of living S. drobachiensis and Lytechinus pictus embryos and the patterns of lectin bindings observed by fluorescence microscopy. The evidence presented in this thesis suggests that the differentiation of the primary mesenchyme cells is correlated with changes in the molecular composition of the cell-surface and the ECM

  16. Population dynamics of Strongylocentrotus droebachiensis in kelpforests and barren grounds in Norway

    DEFF Research Database (Denmark)

    Fagerli, Camilla W.; Gran Stadniczeñko, Sandra; Pedersen, Morten Foldager

    2015-01-01

    A northward trend of declining abundance of sea urchins (Strongylocentrotus droebachiensis) and increasing kelp recovery along the coast of Norway has provided an opportunity to explore whether the decline of sea urchins can be explained by systematic variations in demographic or fitness-related ......A northward trend of declining abundance of sea urchins (Strongylocentrotus droebachiensis) and increasing kelp recovery along the coast of Norway has provided an opportunity to explore whether the decline of sea urchins can be explained by systematic variations in demographic or fitness......-related traits. The population density of sea urchins in mid-Norway (65°70′N) close to the boundary between barren grounds and recently recovered kelp forests was only 26 % of that on barren grounds in northern Norway (70°70′N). Populations were dominated by young (2–4 years) individuals and age-specific numbers...... decreased nearly exponentially with age. The variation in most demographic variables was high among replicate sampling sites and test size. Mean age and growth rates did not differ consistently among sites in mid- and northern Norway nor between barren ground and kelp sites. In contrast, mortality rates...

  17. Caracterización de algunas técnicas de inmunofluorescencia y de fluorescencia en mejillones chilenos Perumytilus purpuratus y Semimytilus algosus

    Directory of Open Access Journals (Sweden)

    Orlando Garrido

    2014-06-01

    Full Text Available Gametos y estadios larvales de los mejillones P. purpuratus y S. algosus fueron tratados in vitro con técnicas de fluorescencia y no fluorescencia a fin de detectar microfilamentos, DNA y gránulos corticales involucrados con estadios de la reproducción como fertilización y clivaje. En P. purouratus se detectó tubulina a nivel de los cilios y el velum; asimismo, la actina fue detectada desde el estadio de fertilización a los estadios de desarrollo tanto en P purpuratus como en S. algosus, lo que sugiere que no son descartados durante el proceso de fertilización. Los microfilamentos detectados en ambos mejillones sugieren que ellos juegan un rol importante como integrante del citoesqueleto durante el desarrollo.

  18. Intrinsic hierarchical structural imperfections in a natural ceramic of bivalve shell with distinctly graded properties.

    Science.gov (United States)

    Jiao, Da; Liu, Zengqian; Zhang, Zhenjun; Zhang, Zhefeng

    2015-07-22

    Despite the extensive investigation on the structure of natural biological materials, insufficient attention has been paid to the structural imperfections by which the mechanical properties of synthetic materials are dominated. In this study, the structure of bivalve Saxidomus purpuratus shell has been systematically characterized quantitatively on multiple length scales from millimeter to sub-nanometer. It is revealed that hierarchical imperfections are intrinsically involved in the crossed-lamellar structure of the shell despite its periodically packed platelets. In particular, various favorable characters which are always pursued in synthetic materials, e.g. nanotwins and low-angle misorientations, have been incorporated herein. The possible contributions of these imperfections to mechanical properties are further discussed. It is suggested that the imperfections may serve as structural adaptations, rather than detrimental defects in the real sense, to help improve the mechanical properties of natural biological materials. This study may aid in understanding the optimizing strategies of structure and properties designed by nature, and accordingly, provide inspiration for the design of synthetic materials.

  19. Aryl sulfate formation in sea urchins (Strongylocentrotus droebachiensis) ingesting marine algae (Fucus distichus) containing 2,6-dimethylnapthalene

    International Nuclear Information System (INIS)

    Malins, D.C.; Roubal, W.T.

    1982-01-01

    The metabolism of tritiated 2,6-dimethylnapthalene (2,6-DMN) was studied in sea urchins (Strongylocentrotus droebachiensis) feeding on marine algae (Fucus distichus). The Fucus accumulated this hydrocarbon from sea water without converting it to metabolites. Most of the tritium accumulated by the sea urchins (e.g., 70.8% after 3 days) from feeding on 2,6-DMN-exposed Fucus was present in the exoskeleton (shell and spines). Moreover, after 3 days feeding, about 90% of the tritium in the total metabolite fraction of the gonads and digestive tract of the sea urchin was present as sulfate derivatives. These metabolites were identified through hydrolysis with aryl sulfatase, followed by thin-layer chromatography of the products. After 14 days of feeding, the tritium associated with the sulfate derivatives decreased in the gonads and digestive tract to 61 and 65%, respectively, of the total metabolite fraction. Hydroxy compounds from sulfatase hydrolysis were chromatographed using multiple elutions with toluene. The hydroxy isomers were separated and the R/sub f/ values were compared to those of pure reference compounds. The data indicated that 80% of the 2,6-dimethylnaphtyl sulfate contained the sulfate on the 1 and/or 3 position of the aromatic ring. Moreover, 6-methyl-2-naphthalenemethanol was not detected, which implies that sea urchins, unlike fish, metabolize alkyl-substituted aromatic hydrocarbons primarily through aromatic ring oxidations

  20. Calidad microbiológica de argopecten purpuratus "concha de abanico" utilizados en acuicultura proveniente de bahía samanco - ancash, 2015

    OpenAIRE

    Espinoza Ramírez, Jessica Karina

    2016-01-01

    The aquaculture activity in Peru has been increasing by national and international demand for seafood products, being one of the products most in demand Argopecten purpuratus "scallops". For this food product is considered apt for human consumption must comply with maximum permissible limits for microbiological parameters of Salmonella: Absence / 25g and E. coli:

  1. Dicty_cDB: Contig-U06881-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available T, clone G000... 44 4.9 1 ( CB077241 ) hj51d10.g1 Hedyotis terminalis flower - Stage 2 (... 44 4.9 1 ( BI739...) 1092959732476 Global-Ocean-Sampling_GS-31-01-01-1... 36 0.16 3 ( EJ122584 ) 1092343379871 Global-Ocean-Sampli...one mth2-12f13... 38 0.28 7 ( EJ342623 ) 1092963526465 Global-Ocean-Sampling_GS-28-01-01-1... 48 0.32 1 ( CE...2 ) 1095469414961 Global-Ocean-Sampling_GS-31-01-01-1... 40 0.59 2 ( AJ871361 ) Nyctotherus ovalis partial g...180574 ) Strongylocentrotus purpuratus clone R3-3095P18, W... 46 1.2 1 ( EJ372544 ) 1092963729038 Global-Ocean-Sampli

  2. Feeding behaviour and growth of the Peruvian scallop (Argopecten purpuratus) under daily cyclic hypoxia conditions

    Science.gov (United States)

    Aguirre-Velarde, Arturo; Jean, Fred; Thouzeau, Gérard; Flye-Sainte-Marie, Jonathan

    2018-01-01

    As a secondary consequence of the high productivity of the upwelling system, organisms inhabiting Peruvian coastal bays are frequently exposed to hypoxic conditions. The aim of the present paper was to investigate the effects of daily-cyclic-severe hypoxia on energetics of a species presenting little escape ability when facing hypoxia. For this purpose, juvenile Peruvian scallops (Argopecten purpuratus) were exposed to four experimental conditions: fed and starved, combined or not to nightly severe hypoxia (5% oxygen saturation) for ≈ 12 h over a 21-day experiment. In both fed conditions, clearance rate was measured by the mean of an open-flow system. Our results indicate that the Peruvian scallop is able to maintain an active filtration even at low oxygen saturation, at least during expositions up to 12 h. During the first phase of exposure to hypoxia, clearance rate decreased abruptly when oxygen saturation dropped below 10%, but rapidly recovered to values close to those found under normoxia. As a consequence of this ability to feed during hypoxia, no difference in soft tissue dry weight (digestive gland not included) was observed at the end of the experimental period between oxic conditions among fed scallops. However, shell growth was negatively affected by hypoxic condition. Starved individuals exhibited similar weight loss between hypoxic and normoxic conditions indicating no or little effect of oxic condition on maintenance costs. Considering the observed responses for feeding, growth and maintenance, we can hypothesize that this species presents metabolic/bioenergetic efficient adaptations to deal with hypoxic conditions that are recurrent in Peruvian coastal bays. We hypothesize that the small observed effects might be modelled in the context of the Dynamic Energy Budget theory as a restriction of reserve mobilization under hypoxic conditions.

  3. Kelp forest monitoring 1993 annual report. Channel Islands National Park. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kushner, D.; Walder, R.; Gorodezky, L.; Lerma, D.; Richards, D.

    1993-06-01

    The 1993 results of the Channel Islands National Park Kelp Forest Monitoring Project are described in this report. Population dynamics of 68 taxa or categories of algea, fish, and invertebrates were measured at 16 permanent sites around the five islands within the park. Survey techniques utilized SCUBA and surface-supplied-air, and included quadrats, band transects, random contacts, fish transects, video transects, size frequency measurements, artificial recruitment modules, and species list surveys. Temperature data was collected using Sea Data batheothermographs, and HOBOTEMP temperature loggers. Temperature loggers were installed at each of the sixteen sites. Size frequency measurements were taken from artifical recruitment modules at nine sites. In 1993, 13 sites had giant kelp, Macrocysts pyrifera, forests, one site was dominated by the aggregating red sea cucumber, pachythyone rubra, one site was dominated by red sea urchins, Strongylocentrotus franciscanus, and another by purple sea urchins, S. purpuratus. The 13 sites with kelp forests consisted of 10 mature and three young kelp forests. Wasting disease was observed in sea stars and wasting syndrome was apparent in sea urchins. Sea urchins wasting syndrome appears to have caused mass mortality of purple sea urchins, S. purpuratus, at two Santa Barbara Island sites.

  4. De novo transcriptome sequencing and comparative analysis to discover genes involved in ovarian maturity in Strongylocentrotus nudus.

    Science.gov (United States)

    Jia, Zhiying; Wang, Qiai; Wu, Kaikai; Wei, Zhenlin; Zhou, Zunchun; Liu, Xiaolin

    2017-09-01

    Strongylocentrotus nudus is an edible sea urchin, mainly harvested in China. Correlation studies indicated that S. nudus with larger diameter have a prolonged marketing time and better palatability owing to their precocious gonads and extended maturation process. However, the molecular mechanism underlying this phenomenon is still unknown. Here, transcriptome sequencing was applied to study the ovaries of adult S. nudus with different shell diameters to explore the possible mechanism. In this study, four independent cDNA libraries were constructed, including two from the big size urchins and two from the small ones using a HiSeq™2500 platform. A total of 88,581 unigenes were acquired with a mean length of 1354bp, of which 66,331 (74.88%) unigenes could be annotated using six major publicly available databases. Comparative analysis revealed that 353 unigenes were differentially expressed (with log2(ratio)≥1, FDR≤0.001) between the two groups. Of these, 20 differentially expressed genes (DEGs) were selected to confirm the accuracy of RNA-seq data by quantitative real-time RT-PCR. Furthermore, gene ontology and KEGG pathway enrichment analyses were performed to find the putative genes and pathways related to ovarian maturity. Eight unigenes were identified as significant DEGs involved in reproduction related pathways; these included Mos, Cdc20, Rec8, YP30, cytochrome P450 2U1, ovoperoxidase, proteoliaisin, and rendezvin. Our research fills the gap in the studies on the S. nudus ovaries using transcriptome analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The test skeletal matrix of the black sea urchin Arbacia lixula.

    Science.gov (United States)

    Kanold, Julia M; Immel, Francoise; Broussard, Cédric; Guichard, Nathalie; Plasseraud, Laurent; Corneillat, Marion; Alcaraz, Gérard; Brümmer, Franz; Marin, Frédéric

    2015-03-01

    In the field of biomineralization, the past decade has been marked by the increasing use of high throughput techniques, i.e. proteomics, for identifying in one shot the protein content of complex macromolecular mixtures extracted from mineralized tissues. Although crowned with success, this approach has been restricted so far to a limited set of key-organisms, such as the purple sea urchin Strongylocentrotus purpuratus, the pearl oyster or the abalone, leaving in the shadow non-model organisms. As a consequence, it is still unknown to what extent the calcifying repertoire varies, from group to group, at high (phylum, class), median (order, family) or low (genus, species) taxonomic rank. The present paper shows the first biochemical and proteomic characterization of the test matrix of the Mediterranean black sea urchin Arbacia lixula (Arbacioida). Our work suggests that the skeletal repertoire of A. lixula exhibits some similarities but also several differences with that of the few sea urchin species (S. purpuratus, Paracentrotus lividus), for which molecular data are already available. The differences may be attributable to the taxonomic position of the species considered: A. lixula belongs to an order - Arbacioida - that diverged more than one hundred million years ago from the Camarodonta, which includes the two species S. purpuratus and P. lividus. For the echinoid class, we suggest that large-scale proteomic screening should be performed in order to understand which molecular functions related to calcification are conserved and which ones have been co-opted for biomineralization in particular lineages. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Spermidine is bound to a unique protein in early sea urchin embryos

    International Nuclear Information System (INIS)

    Canellakis, Z.N.; Bondy, P.K.; Infante, A.A.

    1985-01-01

    Spermidine is rapidly taken up and becomes bound to protein during the very early hours of sea urchin embryogenesis. During the first 6 hr after fertilization of freshly obtained sea urchin eggs (Strongylocentrotus purpuratus), which are incubated in the presence of exogenous [ 3 H]-spermidine, up to 7% of the total cell-associated spermidine appears uniquely as spermidine bound in macromolecular form. This unique protein containing spermidine migrates as a single radioactive band in gel electrophoresis. It has a Mr of approximately equal to 30,000 and is readily distinguishable from the protein initiation factor eIF-4D, which has a Mr of 18,000, the only other identifiable protein known to date to be posttranslationally modified by polyamines

  7. Transgenerational effects of ocean warming on the sea urchin Strongylocentrotus intermedius.

    Science.gov (United States)

    Zhao, Chong; Zhang, Lisheng; Shi, Dongtao; Ding, Jingyun; Yin, Donghong; Sun, Jiangnan; Zhang, Baojing; Zhang, Lingling; Chang, Yaqing

    2018-04-30

    Transgenerational effects, which involve both selection and plasticity, are important for the evolutionary adaptation of echinoderms in the changing ocean. Here, we investigated the effects of breeding design and water temperature for offspring on fertilization, hatchability, larval survival, size, abnormality and metamorphosis of the sea urchin Strongylocentrotus intermedius, whose dams and sires were exposed to long-term (~15 months) elevated temperature (~3°C above ambient) or ambient temperature. There was no transgenerational effect on fertilization and metamorphosis of S. intermedius, while negative transgenerational effects were found in hatchability and most traits of larval size. Dam and sire effects were highly trait and developmental stage dependent. Interestingly, we found S. intermedius probably cannot achieve transgenerational acclimation to long-term elevated temperature for survival provided their offspring were exposed to an elevated temperature. The present study enriches our understanding of transgenerational effects of ocean warming on sea urchins. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. Sclerochronological records and daily microgrowth of the Peruvian scallop (Argopecten purpuratus, Lamarck, 1819) related to environmental conditions in Paracas Bay, Pisco, Peru

    Science.gov (United States)

    Aguirre Velarde, Arturo; Flye-Sainte-Marie, Jonathan; Mendo, Jaime; Jean, Fred

    2015-05-01

    We investigated the rhythm of micro-striae formation in the shell of Argopecten purpuratus and environmental influence on micro-growth increments by monitoring growth over a 98-day period between April and July 2007 under bottom and suspended culture (2 m above the bottom) rearing conditions. The transfer of individuals to the study site induced the formation of a notable growth mark that allowed us to count the number of micro-striae formed between transfer and sampling dates. Micro-striae counts showed a deposition rate of one stria per day independent of rearing condition. This result allowed us to analyse the relationships between growth increments and environmental conditions. We therefore examined the deviations between observed growth rates and growth rates predicted from a Von Bertalanffy growth function. Cross-correlation analysis revealed significant correlations, without time-lag, between these deviations and both particulate organic carbon and nitrogen concentrations in the bottom treatment. Additionally, we observed negative correlations with temperature and current speed at this depth with time-lags of 1 and 10 days respectively. In the suspended treatment, we observed a significant negative correlation with temperature, only with a 12-day lag-time. Our results show that growth response to environmental variability is not always instantaneous. This delay can be explained by the time delay over which metabolic processes need to be performed (e.g. digestion, use/movements of reserves, growth, reproduction). Further modeling studies could help to better understand these processes.

  9. Dicty_cDB: Contig-U01505-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available y1 Gm-c1004 Glycine max cDNA clone GENOME... 32 3.7 2 ( DV211690 ) 0089P0160Z_H09_T7 Mimulus guttatus library 2 Mimu...38TG Tetrahymena thermophila EST library str... 38 2.5 2 ( AC177658 ) Strongylocentrotus purpuratus clone R3...6 1.4 1 ( BG041778 ) saa41a04.y1 Gm-c1059 Glycine soja cDNA clone GENO... 46 1.4 1 ( BF645094 ) NF034E10EC1F1082 Elicited cell cultur...e Medicago t... 46 1.4 1 ( BF644741 ) NF014E01EC1F1005 Elicited cell culture Medica...a oleracea var. alboglabra EST, clone AAF... 44 5.4 1 ( CN828044 ) EL2662R Brassica embryo library (EL) Brassic

  10. Morphological alterations in cryopreserved spermatozoa of scallop Argopecten purpuratus Alteraciones morfológicas en espermatozoides criopreservados de concha de abanico Argopecten purpuratus

    Directory of Open Access Journals (Sweden)

    Carlos Espinoza

    2010-01-01

    Full Text Available The present work identifies and quantifies the morphological alterations of scallop Argopecten purpuratus spermatozoa caused by long-term cryopreservation. Percentages of motility, fertilization and injured spermatozoa were quantified by optic microscopy and scanned electron microscopy. These parameters were evaluated in sperm without treatment (CTR, spermatozoa incubated in cryoprotective solution but not freezed (ICS and freezed-thawed spermatozoa (FTS. Spermatozoa of ICS treatment remained motile longer than those of CTR, whereas those of FTS treatment were lowest. Morphology of the spermatozoa was affected in several ways by the freeze-thawing treatment; some had their head deformed or swollen, others had their cell membrane folded or broken; acrosome reaction; anomalous positions or absence of mitochondria as well as broken, stiff or loss of lineal structure of tail. CTR and ICS treatments had higher percentages of undamaged sperm (87.7% and 79.0% respectively, while FTS samples had 14.2% of undamaged sperm. The tail was the spermatic structure most commonly injured in FTS (77.0%, the percentage of sperm with head injury was 55.1% and with acrosome reaction was 28.7%, whereas middle piece was affected in 23.9% of sperm. Percentages of fertilization were 68.3%, 67.9% and 58.2% for CTR, ICS and FTS respectively, which were not significantly different. There was a higher correlation between injuries and motility than between injuries and fertilization success. Correlation between motility and fertilization was low (0.605 and 0.668 with motility at 5 and 30 min, respectively.El presente trabajo identifica y cuantifica las alteraciones morfológicas en espermatozoides de concha de abanico A. purpuratus causadas por la criopreservación en nitrógeno líquido. Porcentajes de motilidad, fecundación de ovocitos frescos y espermatozoides lesionados (en cabeza, acrosoma, pieza media y flagelo fueron determinados bajo microscopía óptica y electr

  11. Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification, supplement to: Ramajo, L; Marba, Núria; Prado, Luis; Peron, Sophie; Lardies, Marco A; Rodriguez-Navarro, Alejandro; Vargas, C A; Lagos, Nelson A; Duarte, Carlos M (2016): Biomineralization changes with food supply confer juvenile scallops (Argopecten purpuratus) resistance to ocean acidification. Global Change Biology, 22(6), 2025-2037

    KAUST Repository

    Ramajo, L

    2016-01-01

    Future ocean acidification (OA) will affect physiological traits of marine species, with calcifying species being particularly vulnerable. As OA entails high energy demands, particularly during the rapid juvenile growth phase, food supply may play a key role in the response of marine organisms to OA. We experimentally evaluated the role of food supply in modulating physiological responses and biomineralization processes in juveniles of the Chilean scallop, Argopecten purpuratus, that were exposed to control (pH 8.0) and low pH (pH 7.6) conditions using three food supply treatments (high, intermediate, and low). We found that pH and food levels had additive effects on the physiological response of the juvenile scallops. Metabolic rates, shell growth, net calcification, and ingestion rates increased significantly at low pH conditions, independent of food. These physiological responses increased significantly in organisms exposed to intermediate and high levels of food supply. Hence, food supply seems to play a major role modulating organismal response by providing the energetic means to bolster the physiological response of OA stress. On the contrary, the relative expression of chitin synthase, a functional molecule for biomineralization, increased significantly in scallops exposed to low food supply and low pH, which resulted in a thicker periostracum enriched with chitin polysaccharides. Under reduced food and low pH conditions, the adaptive organismal response was to trade-off growth for the expression of biomineralization molecules and altering of the organic composition of shell periostracum, suggesting that the future performance of these calcifiers will depend on the trajectories of both OA and food supply. Thus, incorporating a suite of traits and multiple stressors in future studies of the adaptive organismal response may provide key insights on OA impacts on marine calcifiers.

  12. La bioénergétique du pétoncle péruvien (Argopecten purpuratus) dans un contexte environnemental limitant en oxygène

    OpenAIRE

    Aguirre-Velarde , Arturo

    2016-01-01

    During the past two decades, the scallop (Argopecten Purpuratus) culture developed in the Peruvian coastal bays. The trophic availability linked to the upwelling system supports the production scallop. However, the Peruvian coasts are also known to have a high environmental variability especially in oceanic domain. Although scallop farms are vulnerable to production hazards (mortality, low growth), environmental variability in coastal bays of Peru and its effects on growth, reproduction and s...

  13. Sea urchin akt activity is Runx-dependent and required for post-cleavage stage cell division

    KAUST Repository

    Robertson, Anthony J.

    2013-03-25

    In animal development following the initial cleavage stage of embryogenesis, the cell cycle becomes dependent on intercellular signaling and controlled by the genomically encoded ontogenetic program. Runx transcription factors are critical regulators of metazoan developmental signaling, and we have shown that the sea urchin Runx gene runt-1, which is globally expressed during early embryogenesis, functions in support of blastula stage cell proliferation and expression of the mitogenic genes pkc1, cyclinD, and several wnts. To obtain a more comprehensive list of early runt-1 regulatory targets, we screened a Strongylocentrotus purpuratus microarray to identify genes mis-expressed in mid-blastula stage runt-1 morphants. This analysis showed that loss of Runx function perturbs the expression of multiple genes involved in cell division, including the pro-growth and survival kinase Akt (PKB), which is significantly underexpressed in runt-1 morphants. Further genomic analysis revealed that Akt is encoded by two genes in the S. purpuratus genome, akt-1 and akt-2, both of which contain numerous canonical Runx target sequences. The transcripts of both genes accumulate several fold during blastula stage, contingent on runt-1 expression. Inhibiting Akt expression or activity causes blastula stage cell cycle arrest, whereas overexpression of akt-1 mRNA rescues cell proliferation in runt-1 morphants. These results indicate that post-cleavage stage cell division requires Runx-dependent expression of akt.

  14. Sea urchin akt activity is Runx-dependent and required for post-cleavage stage cell division

    KAUST Repository

    Robertson, Anthony J.; Coluccio, Alison; Jensen, Sarah; Rydlizky, Katarina; Coffman, James A.

    2013-01-01

    In animal development following the initial cleavage stage of embryogenesis, the cell cycle becomes dependent on intercellular signaling and controlled by the genomically encoded ontogenetic program. Runx transcription factors are critical regulators of metazoan developmental signaling, and we have shown that the sea urchin Runx gene runt-1, which is globally expressed during early embryogenesis, functions in support of blastula stage cell proliferation and expression of the mitogenic genes pkc1, cyclinD, and several wnts. To obtain a more comprehensive list of early runt-1 regulatory targets, we screened a Strongylocentrotus purpuratus microarray to identify genes mis-expressed in mid-blastula stage runt-1 morphants. This analysis showed that loss of Runx function perturbs the expression of multiple genes involved in cell division, including the pro-growth and survival kinase Akt (PKB), which is significantly underexpressed in runt-1 morphants. Further genomic analysis revealed that Akt is encoded by two genes in the S. purpuratus genome, akt-1 and akt-2, both of which contain numerous canonical Runx target sequences. The transcripts of both genes accumulate several fold during blastula stage, contingent on runt-1 expression. Inhibiting Akt expression or activity causes blastula stage cell cycle arrest, whereas overexpression of akt-1 mRNA rescues cell proliferation in runt-1 morphants. These results indicate that post-cleavage stage cell division requires Runx-dependent expression of akt.

  15. Boom-to-bust. The scallop (Argopecten purpuratus fishery in the Pisco-Paracas region, southern Peruvian coast Auge y crisis: la pesquería de la concha de abanico (Argopecten purpuratus en la región Pisco-Paracas, costa sur del Perú

    Directory of Open Access Journals (Sweden)

    Ricardo M. González Hunt

    2010-12-01

    Full Text Available This paper examines scallop (Argopecten purpuratus booms experienced in the Pisco-Paracas Region of southern Peru, triggered by the 1982-1983 and the 1997-1998 mega-El Niño Southern Oscillation (ENSO events.The quiet fishing ports have been transformed by these booms, which have attracted outside stakeholders transforming the local society. Government institutions in their role as resource managers and environmental stewards have attempted to control access to a region that until recently contained the only marine protected area of Peru.This situation has led to rapid growth in the scallop industry, the overexploitation and depletion of the shellfish, creating a sustainability crisis. Furthermore, this paper examines contradictions and relationships across local, regional, national, and international scales.Este trabajo examina los ciclos de expansión (boom de la explotación de la concha de abanico (Argopecten purpuratus observados en la región Pisco-Paracas del sur del Perú, resultantes de los fenómenos El Niño de 1982-1983 y 1997-1998.Los apacibles puertos de pesca han sido transformados por estos booms productivos que han atraído actores externos y han generado un impacto en la sociedad local. Las instituciones gubernamentales, en su papel de administradores de recursos y protectores del medio ambiente, han tratado de controlar el acceso a una región que hasta hace poco contenía la única área marina protegida del Perú.Esta situación ha producido un rápido crecimiento de la industria de la concha de abanico, su sobreexplotación y el agotamiento de dicho recurso, y ha producido una crisis de sostenibilidad. Asimismo, este trabajo examina las contradicciones y las relaciones entre las escalas local, regional, nacional e internacional.

  16. Effect of temperature on physiological responses of Peruvian scallop Argopecten purpuratus

    Directory of Open Access Journals (Sweden)

    Jhon Dionicio Acedo

    2015-12-01

    Full Text Available The effect of temperature on the clearance rate (CR, ingestion rate (IR and specific oxygen consumption (SOC in individuals of Argopecten purpuratus at different size groups were determined. The CR and IR tests were performed at a concentration of approximately 1x106 cel.mlL-1 of Chaetoceros calcitrans, two temperatures 17 and 22 °C were evaluated and different groups of average size were formed of 7.6 ± 0.265, and 0.058 ± 4.9 3.7 ± 0.173 cm. In SOC test the average size groups were 8.1 ± 0.351, 0.058 ± 5.6 and 4.3 ± 0.100 cm. The results show a significant effect of temperature in CR (Lh-1 and IR (cel.h-1 x 105 on the larger individuals (7.6 ± 0.265 cm, it was observed at 22 °C an average increase, about 17 °C, up to 250% to CR and 48% to IR. In addition, a direct relationship of body size with CR and IR in both temperatures was observed. The effect of temperature at 22 ° C on SOC in all groups was evaluated, with an increase of 239.8, 165.3 and 183.4% for size individuals of 8.1 ± 0.351, 0.058 ± 5.6 and 4.3 ± 0.100 respectively. Furthermore, in both evaluated temperatures, the results show an indirect relationship of body size with the SOC.

  17. Germ line determinants are not localized early in sea urchin development, but do accumulate in the small micromere lineage.

    Science.gov (United States)

    Juliano, Celina E; Voronina, Ekaterina; Stack, Christie; Aldrich, Maryanna; Cameron, Andrew R; Wessel, Gary M

    2006-12-01

    Two distinct modes of germ line determination are used throughout the animal kingdom: conditional-an inductive mechanism, and autonomous-an inheritance of maternal factors in early development. This study identifies homologs of germ line determinants in the sea urchin Strongylocentrotus purpuratus to examine its mechanism of germ line determination. A list of conserved germ-line associated genes from diverse organisms was assembled to search the S. purpuratus genome for homologs, and the expression patterns of these genes were examined during embryogenesis by whole mount in situ RNA hybridization and QPCR. Of the 14 genes tested, all transcripts accumulate uniformly during oogenesis and Sp-pumilio, Sp-tudor, Sp-MSY, and Sp-CPEB1 transcripts are also uniformly distributed during embryonic development. Sp-nanos2, Sp-seawi, and Sp-ovo transcripts, however, are enriched in the vegetal plate of the mesenchyme blastula stage and Sp-vasa, Sp-nanos2, Sp-seawi, and Sp-SoxE transcripts are localized in small micromere descendents at the tip of the archenteron during gastrulation and are then enriched in the left coelomic pouch of larvae. The results of this screen suggest that sea urchins conditionally specify their germ line, and support the hypothesis that this mechanism is the basal mode of germ line determination amongst deuterostomes. Furthermore, accumulation of germ line determinants selectively in small micromere descendents supports the hypothesis that these cells contribute to the germ line.

  18. Expression pattern of vascular endothelial growth factor 2 during sea urchin development.

    Science.gov (United States)

    Kipryushina, Yulia O; Yakovlev, Konstantin V; Kulakova, Milana A; Odintsova, Nelly A

    2013-12-01

    The VEGF family in the sea urchin is comprised of three members designated Vegf1 through Vegf3. In this study, we found a high level of similarity between the PDGF/VEGF domain of the predicted gene Sp-Vegf2 in the sea urchin Strongylocentrotus purpuratus and the same domain of a gene that we found in a closely related sea urchin, Strongylocentrotus intermedius. The sequence of the Si-Vegf2 cDNA was determined, and the expression of the Si-Vegf2 mRNA throughout early sea urchin development was studied by RT-PCR and in situ hybridization. Also we analyzed phylogenetic relationships of Si-Vegf2 and other members of the PDGF and VEGF families. We have found that the Si-Vegf2 present during the time span from the egg to the 4-arm pluteus stage. This mRNA is uniformly distributed in eggs, cleaving embryos and early blastulae. At the gastrula stage, the Si-Vegf2 transcripts are localized in the ventrolateral clusters of primary mesenchyme cells, and later, at the prism stage, they are detected in the forming apex. At the early pluteus stage, Si-Vegf2 mRNAs are found in two groups of mesenchyme cells in the scheitel region on the apical pole. We have determined that Si-Vegf2 is a mesenchyme-expressed factor but its developmental function is unknown. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Effects of light and covering behavior on PAX6 expression in the sea urchin Strongylocentrotus intermedius.

    Directory of Open Access Journals (Sweden)

    Chong Zhao

    Full Text Available We studied the diel expression pattern of PAX6 (a structural gene that is commonly involved in the eye development and photoreception of eye forming animals and the effects of light and covering behavior on PAX6 expression in the sea urchin Strongylocentrotus intermedius. We confirmed that aphotic condition significantly reduced covering behavior in S. intermedius. The diel expression pattern of PAX6 was significantly different in S. intermedius under photic and aphotic conditions. The gene expression of PAX6 significantly deceased in covered S. intermedius both under natural light and in darkness. The present finding provides valuable insight into the probable link between covering and PAX6 expression of sea urchins. Further studies are required to investigate the detailed expression network of light detection involved genes in order to fully reveal the molecular mechanism of the light-induced covering behavior of sea urchins.

  20. Comparison of the disposition of several nitrogen-containing compounds in the sea urchin and other marine invertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Landrum, P.F.; Crosby, D.G.

    1981-01-01

    1. The disposition of an aromatic amine and three aromatic nitro compounds was investigated in the sea urchin, Strongylocentrotus purpuratus. 2. The sea urchin rapidly eliminated injected compounds. The elimination rate constants decreased in the order p-toluidine greater than p-nitroanisole . p-nitrophenol greater than p-nitrotoluene. The fraction of total injected compound eliminated in 8 h was lowest for p-nitrophenol less than p-toluidine less than p-nitrotoluene less than p-nitroanisole. 3. Biotransformation for the sea urchin was primarily reduction of the nitro group followed by acetylation of the amine. 4. Other animals, starfish (Pisaster ochraceus), sea cucumber (Cucumaria miniata), gum boot chiton (Cryptochiton stelleri) and mussels (Mytilus californianus), injected with p-nitroanisole exhibited a trend toward oxidative biotransformation. 5. Elimination of parent compound was the major pathway for reducing body burden of xenobiotics for the invertebrates studied. 6. p-Toluidine oxidizes during analysis and was thus not suitable for studying biotransformation.

  1. Unusual Gene Order and Organization of the Sea Urchin HoxCluster

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Paul M.; Lucas, Susan; Cameron, R. Andrew; Rowen,Lee; Nesbitt, Ryan; Bloom, Scott; Rast, Jonathan P.; Berney, Kevin; Arenas-Mena, Cesar; Martinez, Pedro; Davidson, Eric H.; Peterson, KevinJ.; Hood, Leroy

    2005-05-10

    The highly consistent gene order and axial colinear expression patterns found in vertebrate hox gene clusters are less well conserved across the rest of bilaterians. We report the first deuterostome instance of an intact hox cluster with a unique gene order where the paralog groups are not expressed in a sequential manner. The finished sequence from BAC clones from the genome of the sea urchin, Strongylocentrotus purpuratus, reveals a gene order wherein the anterior genes (Hox1, Hox2 and Hox3) lie nearest the posterior genes in the cluster such that the most 3' gene is Hox5. (The gene order is : 5'-Hox1,2, 3, 11/13c, 11/13b, '11/13a, 9/10, 8, 7, 6, 5 - 3)'. The finished sequence result is corroborated by restriction mapping evidence and BAC-end scaffold analyses. Comparisons with a putative ancestral deuterostome Hox gene cluster suggest that the rearrangements leading to the sea urchin gene order were many and complex.

  2. Exploring the Sea Urchin Neuropeptide Landscape by Mass Spectrometry.

    Science.gov (United States)

    Monroe, Eric B; Annangudi, Suresh P; Wadhams, Andinet A; Richmond, Timothy A; Yang, Ning; Southey, Bruce R; Romanova, Elena V; Schoofs, Liliane; Baggerman, Geert; Sweedler, Jonathan V

    2018-05-01

    Neuropeptides are essential cell-to-cell signaling messengers and serve important regulatory roles in animals. Although remarkable progress has been made in peptide identification across the Metazoa, for some phyla such as Echinodermata, limited neuropeptides are known and even fewer have been verified on the protein level. We employed peptidomic approaches using bioinformatics and mass spectrometry (MS) to experimentally confirm 23 prohormones and to characterize a new prohormone in nervous system tissue from Strongylocentrotus purpuratus, the purple sea urchin. Ninety-three distinct peptides from known and novel prohormones were detected with MS from extracts of the radial nerves, many of which are reported or experimentally confirmed here for the first time, representing a large-scale study of neuropeptides from the phylum Echinodermata. Many of the identified peptides and their precursor proteins have low homology to known prohormones from other species/phyla and are unique to the sea urchin. By pairing bioinformatics with MS, the capacity to characterize novel peptides and annotate prohormone genes is enhanced. Graphical Abstract.

  3. Expression, purification, crystallization and preliminary X-ray analysis of the olfactomedin domain from the sea urchin cell-adhesion protein amassin

    International Nuclear Information System (INIS)

    Hillier, Brian J.; Sundaresan, Vidyasankar; Stout, C. David; Vacquier, Victor D.

    2005-01-01

    The olfactomedin (OLF) domain from the sea urchin cell-adhesion protein amassin has been crystallized. A native data set extending to 2.7 Å has been collected using an in-house X-ray source. A family of animal proteins is emerging which contain a conserved protein motif known as an olfactomedin (OLF) domain. Novel extracellular protein–protein interactions occur through this domain. The OLF-family member amassin, from the sea urchin Strongylocentrotus purpuratus, has previously been identified to mediate a rapid cell-adhesion event resulting in a large aggregation of coelomocytes, the circulating immune cells. In this work, heterologous expression and purification of the OLF domain from amassin was carried out and initial crystallization trials were performed. A native data set has been collected, extending to 2.7 Å under preliminary cryoconditions, using an in-house generator. This work leads the way to the determination of the first structure of an OLF domain

  4. The impact of gene expression variation on the robustness and evolvability of a developmental gene regulatory network.

    Directory of Open Access Journals (Sweden)

    David A Garfield

    2013-10-01

    Full Text Available Regulatory interactions buffer development against genetic and environmental perturbations, but adaptation requires phenotypes to change. We investigated the relationship between robustness and evolvability within the gene regulatory network underlying development of the larval skeleton in the sea urchin Strongylocentrotus purpuratus. We find extensive variation in gene expression in this network throughout development in a natural population, some of which has a heritable genetic basis. Switch-like regulatory interactions predominate during early development, buffer expression variation, and may promote the accumulation of cryptic genetic variation affecting early stages. Regulatory interactions during later development are typically more sensitive (linear, allowing variation in expression to affect downstream target genes. Variation in skeletal morphology is associated primarily with expression variation of a few, primarily structural, genes at terminal positions within the network. These results indicate that the position and properties of gene interactions within a network can have important evolutionary consequences independent of their immediate regulatory role.

  5. Proteome-wide dataset supporting the study of ancient metazoan macromolecular complexes

    Directory of Open Access Journals (Sweden)

    Sadhna Phanse

    2016-03-01

    Full Text Available Our analysis examines the conservation of multiprotein complexes among metazoa through use of high resolution biochemical fractionation and precision mass spectrometry applied to soluble cell extracts from 5 representative model organisms Caenorhabditis elegans, Drosophila melanogaster, Mus musculus, Strongylocentrotus purpuratus, and Homo sapiens. The interaction network obtained from the data was validated globally in 4 distant species (Xenopus laevis, Nematostella vectensis, Dictyostelium discoideum, Saccharomyces cerevisiae and locally by targeted affinity-purification experiments. Here we provide details of our massive set of supporting biochemical fractionation data available via ProteomeXchange (http://www.ebi.ac.uk/pride/archive/projects/PXD002319-http://www.ebi.ac.uk/pride/archive/projects/PXD002328, PPIs via BioGRID (185267; and interaction network projections via (http://metazoa.med.utoronto.ca made fully accessible to allow further exploration. The datasets here are related to the research article on metazoan macromolecular complexes in Nature [1]. Keywords: Proteomics, Metazoa, Protein complexes, Biochemical, Fractionation

  6. In-depth, high-accuracy proteomics of sea urchin tooth organic matrix

    Directory of Open Access Journals (Sweden)

    Mann Matthias

    2008-12-01

    Full Text Available Abstract Background The organic matrix contained in biominerals plays an important role in regulating mineralization and in determining biomineral properties. However, most components of biomineral matrices remain unknown at present. In sea urchin tooth, which is an important model for developmental biology and biomineralization, only few matrix components have been identified. The recent publication of the Strongylocentrotus purpuratus genome sequence rendered possible not only the identification of genes potentially coding for matrix proteins, but also the direct identification of proteins contained in matrices of skeletal elements by in-depth, high-accuracy proteomic analysis. Results We identified 138 proteins in the matrix of tooth powder. Only 56 of these proteins were previously identified in the matrices of test (shell and spine. Among the novel components was an interesting group of five proteins containing alanine- and proline-rich neutral or basic motifs separated by acidic glycine-rich motifs. In addition, four of the five proteins contained either one or two predicted Kazal protease inhibitor domains. The major components of tooth matrix were however largely identical to the set of spicule matrix proteins and MSP130-related proteins identified in test (shell and spine matrix. Comparison of the matrices of crushed teeth to intact teeth revealed a marked dilution of known intracrystalline matrix proteins and a concomitant increase in some intracellular proteins. Conclusion This report presents the most comprehensive list of sea urchin tooth matrix proteins available at present. The complex mixture of proteins identified may reflect many different aspects of the mineralization process. A comparison between intact tooth matrix, presumably containing odontoblast remnants, and crushed tooth matrix served to differentiate between matrix components and possible contributions of cellular remnants. Because LC-MS/MS-based methods directly

  7. Comparación del crecimiento de Argopecten purpuratus entre cohortes obtenidas de captación de larvas en ambiente natural y de hatchery Comparison of growth among cohorts obtained Argopecten purpuratus larval recruitment in natural and hatchery

    Directory of Open Access Journals (Sweden)

    Eduardo P Pérez

    2012-11-01

    Full Text Available En Chile los cultivos del ostión del norte Argopecten purpuratus han sido desarrollados intensivamente a partir de la captación de semillas en ambiente natural y desde principios de 1980 con semillas obtenidas en hatchery. Para aportar información sobre el desempeno de semillas de ostión del norte en este estudio se comparó, mediante ANCOVA, el crecimiento en longitud entre cohortes producidas a partir de semillas de ambiente natural y de hatchery en Tongoy, Chile. Se evaluó la consistencia de esta comparación en distintos anos y estaciones, comparándose parejas de cohortes producidas simultáneamente en los anos 2003 (primavera, 2005 (invierno y 2006 (verano. El análisis estadístico mostró que existen diferencias estadísticas significativas entre cohortes obtenidas en ambiente natural y aquellas obtenidas en hatchery. La prueba de Tukey evidenció diferencias significativas entre CN2003 y CH2003 como también entre CN2005 y CH2005, pero no así entre CN2006 y CH2006. Estas diferencias indican que las cohortes de semillas de ambiente natural crecieron más rápido que las de hatchery. La comparación interanual evidenció diferencias estadísticas significativas. Estos resultados son discutidos a la luz de dos factores: la temperatura de cultivo y la heterocigocidad de la población de cultivo.In Chile crops of the northern scallop Argopecten purpuratus have been developed intensively from seeds obtained in natural environment, and since 1980 from hatchery's seed, when this technique could be controlled and developed. In order to provide information on the performance of seeds of northern scallops in this study growth in length between cohorts produced from seeds obtained in natural environment (CN and hatchery (CH in Tongoy (Chile was compared using ANCOVA. We assessed the consistency of this comparison in different years and seasons. The compared cohorts are pairs of cohorts produced simultaneously in the years 2003 (spring, 2005

  8. Evaluación en ambiente natural, del uso de biopelículas marinas en el asentamiento larval de Argopecten purpuratus (Lamarck, 1819 Evaluation in natural environment of use of marine biofilms, in the larval settlement of Argopecten purpuratus (Lamarck, 1819

    Directory of Open Access Journals (Sweden)

    Marcela Cantillánez

    2010-01-01

    Full Text Available En una granja marina ubicada colindante con el área de reserva marina “La Rinconada” (Antofagasta, Chile, se evaluó el asentamiento larval del pectínido Argopecten purpuratus sobre colectores impregnados con películas multi-específicas, de las diatomeas Navicula sp. y Amphora sp., y de la cepa bacteriana NC1, aisladas desde colectores utilizados en captaciones comerciales de esta especie que presentaron altos índices de fijación, y que bajo condiciones controladas de criadero y laboratorio, han mostrando altos niveles de asentamiento larval. Los resultados obtenidos con el uso de estas biopelículas, sobre colectores instalados en forma paralela a los utilizados por la empresa para la captación de semilla con fines comerciales, no mostraron diferencias significativas entre los diferentes tratamientos probados y el control, respecto a las fijaciones ocurridas en un lapso de 30 días de inmersión. Se discute, debido a los tiempos que demandaron las larvas de la primera cohorte en asentarse sobre los colectores tratados, un posible reemplazo de las biopelículas utilizadas, por otra común en todos ellos y atractiva para el asentamiento de las larvas, como causa de la ausencia de efectos significativos de los tratamientos probados en el medio natural. Se recomienda la necesidad de establecer el tiempo de permanencia, en el ambiente natural, de las biopelículas impregnadas a los colectores en laboratorio.In a commercial farm located near the Marine Reserve “La Rinconada” (Antofagasta, Chile the larval settlement of Argopecten purpuratus on artificial collectors impregnated with multiespecific films of marine diatoms Navicula sp. and Amphora sp. and, bacterial strain NC1 were evaluated, These biofilms were isolates from artificial collector used in commercial activities with highest index of settlement in hatchery and laboratory conditions. The results to use this biofilms in collectors installed in same condition of commercial

  9. Reproductive and larval cycle of the scallop Argopecten purpuratus (Ostreoida: Pectinidae, during El Niño-La Niña events and normal weather conditions in Antofagasta, Chile

    Directory of Open Access Journals (Sweden)

    Miguel Avendaño

    2008-03-01

    Full Text Available Seasonality, amplitude, and magnitude of spawning events were determined for Argopecten purpuratus in the La Rinconada marine reserve, Antofagasta, Chile, between December 1995 and January 2004. During the same period, samples of scallop larvae were obtained in vertical plankton hauls recovered within this reserve in an area routinely exposed to circular, gyre-like currents which helped retain the larvae within the bay. The reproduction of this population in normal or cool (e.g. "La Niña", 1998-2000 years occurred throughout the year, with a more active period between September and April, declining in June and August; this contrasted with the warmer "El Niño" oceanographic period of 1997-98 in which reproductive activity was more intense and prolonged throughout the entire year. The reproductive events in this population were mostly synchronous, although one asynchronous period occurred each year following the more intense March to May spawnings. This reproductive activity generated a continuous presence of larvae in the area in which no strict relation could be found between the intensities of spawning and numbers of larvae in the water. Larval presence was, however, generally correlated with active spawning periods. Important increases in larval numbers recorded at the end of 1999 and the beginning of 2003 were correlated with census data showing a higher percentage presence of broodstock over 90 mm in shell length during these years. An adequate stock of this size class is needed for a successful seed capture program in the reserve (for mass culture. Rev. Biol. Trop. 56 (1: 121-132. Epub 2008 March 31.Entre 1995 y 2004 se determinó, con el índice gonadosomático, el ciclo reproductivo de Argopecten purpuratus en La Rinconada, Antofagasta, Chile. Paralelamente se realizaron muestreos larvales mediante arrastres verticales de plancton. La reproducción, en años normales y fríos (La Niña, 1998-2000, ocurre todo el año, con un período m

  10. Physiological effects of environmental acidification in the deep-sea urchin Strongylocentrotus fragilis

    Science.gov (United States)

    Taylor, J. R.; Lovera, C.; Whaling, P. J.; Buck, K. R.; Pane, E. F.; Barry, J. P.

    2014-03-01

    Anthropogenic CO2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of elevated pCO2 and variable O2 on the deep-sea urchin Strongylocentrotus fragilis, a species whose range of 200-1200 m depth includes the OMZ and spans a pCO2 range of approx. 600-1200 μatm (approx. pH 7.6 to 7.8). Individuals were evaluated during two exposure experiments (1-month and 4 month) at control and three levels of elevated pCO2 at in situ O2 levels of approx. 10% air saturation. A treatment of control pCO2 at 100% air saturation was also included in experiment two. During the first experiment, perivisceral coelomic fluid (PCF) acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by elevated pCO2, due in part to low non-bicarbonate PCF buffering capacity. During the second experiment, individuals were separated into fed and fasted experimental groups, and longer-term effects of elevated pCO2 and variable O2 on righting time, feeding, growth, and gonadosomatic index (GSI) were investigated for both groups. Results suggest that the acidosis found during experiment one does not directly correlate with adverse effects during exposure to realistic future pCO2 levels.

  11. SoxB2 in sea urchin development: implications in neurogenesis, ciliogenesis and skeletal patterning.

    Science.gov (United States)

    Anishchenko, Evgeniya; Arnone, Maria Ina; D'Aniello, Salvatore

    2018-01-01

    Current studies in evolutionary developmental biology are focused on the reconstruction of gene regulatory networks in target animal species. From decades, the scientific interest on genetic mechanisms orchestrating embryos development has been increasing in consequence to the fact that common features shared by evolutionarily distant phyla are being clarified. In 2011, a study across eumetazoan species showed for the first time the existence of a highly conserved non-coding element controlling the SoxB2 gene, which is involved in the early specification of the nervous system. This discovery raised several questions about SoxB2 function and regulation in deuterostomes from an evolutionary point of view. Due to the relevant phylogenetic position within deuterostomes, the sea urchin Strongylocentrotus purpuratus represents an advantageous animal model in the field of evolutionary developmental biology. Herein, we show a comprehensive study of SoxB2 functions in sea urchins, in particular its expression pattern in a wide range of developmental stages, and its co-localization with other neurogenic markers, as SoxB1 , SoxC and Elav . Moreover, this work provides a detailed description of the phenotype of sea urchin SoxB2 knocked-down embryos, confirming its key function in neurogenesis and revealing, for the first time, its additional roles in oral and aboral ectoderm cilia and skeletal rod morphology. We concluded that SoxB2 in sea urchins has a neurogenic function; however, this gene could have multiple roles in sea urchin embryogenesis, expanding its expression in non-neurogenic cells. We showed that SoxB2 is functionally conserved among deuterostomes and suggested that in S. purpuratus this gene acquired additional functions, being involved in ciliogenesis and skeletal patterning.

  12. Transcriptomic responses to ocean acidification in larval sea urchins from a naturally variable pH environment.

    Science.gov (United States)

    Evans, Tyler G; Chan, Francis; Menge, Bruce A; Hofmann, Gretchen E

    2013-03-01

    Some marine ecosystems already experience natural declines in pH approximating those predicted with future anthropogenic ocean acidification (OA), the decline in seawater pH caused by the absorption of atmospheric CO2 . The molecular mechanisms that allow organisms to inhabit these low pH environments, particularly those building calcium carbonate skeletons, are unknown. Also uncertain is whether an enhanced capacity to cope with present day pH variation will confer resistance to future OA. To address these issues, we monitored natural pH dynamics within an intertidal habitat in the Northeast Pacific, demonstrating that upwelling exposes resident species to pH regimes not predicted to occur elsewhere until 2100. Next, we cultured the progeny of adult purple sea urchins (Strongylocentrotus purpuratus) collected from this region in CO2 -acidified seawater representing present day and near future ocean scenarios and monitored gene expression using transcriptomics. We hypothesized that persistent exposure to upwelling during evolutionary history will have selected for increased pH tolerance in this population and that their transcriptomic response to low pH seawater would provide insight into mechanisms underlying pH tolerance in a calcifying species. Resulting expression patterns revealed two important trends. Firstly, S. purpuratus larvae may alter the bioavailability of calcium and adjust skeletogenic pathways to sustain calcification in a low pH ocean. Secondly, larvae use different strategies for coping with different magnitudes of pH stress: initiating a robust transcriptional response to present day pH regimes but a muted response to near future conditions. Thus, an enhanced capacity to cope with present day pH variation may not translate into success in future oceans. © 2013 Blackwell Publishing Ltd.

  13. Exploring the Sea Urchin Neuropeptide Landscape by Mass Spectrometry

    Science.gov (United States)

    Monroe, Eric B.; Annangudi, Suresh P.; Wadhams, Andinet A.; Richmond, Timothy A.; Yang, Ning; Southey, Bruce R.; Romanova, Elena V.; Schoofs, Liliane; Baggerman, Geert; Sweedler, Jonathan V.

    2018-04-01

    Neuropeptides are essential cell-to-cell signaling messengers and serve important regulatory roles in animals. Although remarkable progress has been made in peptide identification across the Metazoa, for some phyla such as Echinodermata, limited neuropeptides are known and even fewer have been verified on the protein level. We employed peptidomic approaches using bioinformatics and mass spectrometry (MS) to experimentally confirm 23 prohormones and to characterize a new prohormone in nervous system tissue from Strongylocentrotus purpuratus, the purple sea urchin. Ninety-three distinct peptides from known and novel prohormones were detected with MS from extracts of the radial nerves, many of which are reported or experimentally confirmed here for the first time, representing a large-scale study of neuropeptides from the phylum Echinodermata. Many of the identified peptides and their precursor proteins have low homology to known prohormones from other species/phyla and are unique to the sea urchin. By pairing bioinformatics with MS, the capacity to characterize novel peptides and annotate prohormone genes is enhanced. [Figure not available: see fulltext.

  14. SM30 protein function during sea urchin larval spicule formation.

    Science.gov (United States)

    Wilt, Fred; Killian, Christopher E; Croker, Lindsay; Hamilton, Patricia

    2013-08-01

    A central issue in better understanding the process of biomineralization is to elucidate the function of occluded matrix proteins present in mineralized tissues. A potent approach to addressing this issue utilizes specific inhibitors of expression of known genes. Application of antisense oligonucleotides that specifically suppress translation of a given mRNA are capable of causing aberrant biomineralization, thereby revealing, at least in part, a likely function of the protein and gene under investigation. We have applied this approach to study the possible function(s) of the SM30 family of proteins, which are found in spicules, teeth, spines, and tests of Strongylocentrotus purpuratus as well as other euechinoid sea urchins. It is possible using the anti-SM30 morpholino-oligonucleotides (MO's) to reduce the level of these proteins to very low levels, yet the development of skeletal spicules in the embryo shows little or no aberration. This surprising result requires re-thinking about the role of these, and possibly other occluded matrix proteins. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Asymmetric distribution of hypoxia-inducible factor α regulates dorsoventral axis establishment in the early sea urchin embryo.

    Science.gov (United States)

    Chang, Wei-Lun; Chang, Yi-Cheng; Lin, Kuan-Ting; Li, Han-Ru; Pai, Chih-Yu; Chen, Jen-Hao; Su, Yi-Hsien

    2017-08-15

    Hypoxia signaling is an ancient pathway by which animals can respond to low oxygen. Malfunction of this pathway disturbs hypoxic acclimation and can result in various diseases, including cancers. The role of hypoxia signaling in early embryogenesis remains unclear. Here, we show that in the blastula of the sea urchin Strongylocentrotus purpuratus , hypoxia-inducible factor α (HIFα), the downstream transcription factor of the hypoxia pathway, is localized and transcriptionally active on the future dorsal side. This asymmetric distribution is attributable to its oxygen-sensing ability. Manipulations of the HIFα level entrained the dorsoventral axis, as the side with the higher level of HIFα tends to develop into the dorsal side. Gene expression analyses revealed that HIFα restricts the expression of nodal to the ventral side and activates several genes encoding transcription factors on the dorsal side. We also observed that intrinsic hypoxic signals in the early embryos formed a gradient, which was disrupted under hypoxic conditions. Our results reveal an unprecedented role of the hypoxia pathway in animal development. © 2017. Published by The Company of Biologists Ltd.

  16. Exploring the Sea Urchin Neuropeptide Landscape by Mass Spectrometry

    Science.gov (United States)

    Monroe, Eric B.; Annangudi, Suresh P.; Wadhams, Andinet A.; Richmond, Timothy A.; Yang, Ning; Southey, Bruce R.; Romanova, Elena V.; Schoofs, Liliane; Baggerman, Geert; Sweedler, Jonathan V.

    2018-05-01

    Neuropeptides are essential cell-to-cell signaling messengers and serve important regulatory roles in animals. Although remarkable progress has been made in peptide identification across the Metazoa, for some phyla such as Echinodermata, limited neuropeptides are known and even fewer have been verified on the protein level. We employed peptidomic approaches using bioinformatics and mass spectrometry (MS) to experimentally confirm 23 prohormones and to characterize a new prohormone in nervous system tissue from Strongylocentrotus purpuratus, the purple sea urchin. Ninety-three distinct peptides from known and novel prohormones were detected with MS from extracts of the radial nerves, many of which are reported or experimentally confirmed here for the first time, representing a large-scale study of neuropeptides from the phylum Echinodermata. Many of the identified peptides and their precursor proteins have low homology to known prohormones from other species/phyla and are unique to the sea urchin. By pairing bioinformatics with MS, the capacity to characterize novel peptides and annotate prohormone genes is enhanced. [Figure not available: see fulltext.

  17. Lesions of Copper Toxicosis in Captive Marine Invertebrates With Comparisons to Normal Histology.

    Science.gov (United States)

    LaDouceur, E E B; Wynne, J; Garner, M M; Nyaoke, A; Keel, M K

    2016-05-01

    Despite increasing concern for coral reef ecosystem health within the last decade, there is scant literature concerning the histopathology of diseases affecting the major constituents of coral reef ecosystems, particularly marine invertebrates. This study describes histologic findings in 6 species of marine invertebrates (California sea hare [Aplysia californica], purple sea urchin [Strongylocentrotus purpuratus], sunburst anemone [Anthopleura sola], knobby star [Pisaster giganteus], bat star [Asterina miniata], and brittle star [Ophiopteris papillosa]) with spontaneous copper toxicosis, 4 purple sea urchins with experimentally induced copper toxicosis, and 1 unexposed control of each species listed. The primary lesions in the California sea hare with copper toxicosis were branchial and nephridial necrosis. Affected echinoderms shared several histologic lesions, including epidermal necrosis and ulceration and increased numbers of coelomocytes within the water-vascular system. The sunburst anemone with copper toxicosis had necrosis of both epidermis and gastrodermis, as well as expulsion of zooxanthellae from the gastrodermis. In addition to the lesions attributed to copper toxicosis, our results describe normal microscopic features of these animals that may be useful for histopathologic assessment of marine invertebrates. © The Author(s) 2015.

  18. Proteomic profiles reveal age-related changes in coelomic fluid of sea urchin species with different life spans.

    Science.gov (United States)

    Bodnar, Andrea

    2013-05-01

    Sea urchins have a different life history from humans and traditional model organisms used to study the process of aging. Sea urchins grow indeterminately, reproduce throughout their life span and some species have been shown to exhibit negligible senescence with no increase in mortality rate at advanced ages. Despite these properties, different species of sea urchins are reported to have very different natural life spans providing a unique model to investigate cellular mechanisms underlying life span determination and negligible senescence. To gain insight into the biological changes that accompany aging in these animals, proteomic profiles were examined in coelomic fluid from young and old sea urchins of three species with different life spans: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate life span. The proteomic profiles of cell-free coelomic fluid were complex with many proteins exhibiting different forms and extensive post-translational modifications. Approximately 20% of the protein spots on 2-D gels showed more than two-fold change with age in each of the species. Changes that are consistent with age in all three species may prove to be useful biomarkers for age-determination for these commercially fished marine invertebrates and also may provide clues to mechanisms of negligible senescence. Among the proteins that change with age, the ectodomain of low-density lipoprotein receptor-related protein 4 (LRP4) was significantly increased in the coelomic fluid of all three sea urchin species suggesting that the Wnt signaling pathway should be further investigated for its role in negligible senescence. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. NIF Double Shell outer/inner shell collision experiments

    Science.gov (United States)

    Merritt, E. C.; Loomis, E. N.; Wilson, D. C.; Cardenas, T.; Montgomery, D. S.; Daughton, W. S.; Dodd, E. S.; Desjardins, T.; Renner, D. B.; Palaniyappan, S.; Batha, S. H.; Khan, S. F.; Smalyuk, V.; Ping, Y.; Amendt, P.; Schoff, M.; Hoppe, M.

    2017-10-01

    Double shell capsules are a potential low convergence path to substantial alpha-heating and ignition on NIF, since they are predicted to ignite and burn at relatively low temperatures via volume ignition. Current LANL NIF double shell designs consist of a low-Z ablator, low-density foam cushion, and high-Z inner shell with liquid DT fill. Central to the Double Shell concept is kinetic energy transfer from the outer to inner shell via collision. The collision determines maximum energy available for compression and implosion shape of the fuel. We present results of a NIF shape-transfer study: two experiments comparing shape and trajectory of the outer and inner shells at post-collision times. An outer-shell-only target shot measured the no-impact shell conditions, while an `imaging' double shell shot measured shell conditions with impact. The `imaging' target uses a low-Z inner shell and is designed to perform in similar collision physics space to a high-Z double shell but can be radiographed at 16keV, near the viable 2DConA BL energy limit. Work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.

  20. Elimination of vibrio cholerae El Tor, in scallops (Argopecten purpuratus) by gamma radiation and product organoleptic evaluation

    International Nuclear Information System (INIS)

    Torres, Z.; Bernuy, B.; Vivanco, M.; Kahn, G.

    1999-03-01

    V. cholerae D 10 value in scallops (Argopecten purpuratus) was determined in vivo. D 10 was found to be 0,143 kGy, requiring therefore the application of 8D in scallops, equivalent to a 1,14 kGy dose, the optimal dose for life span extension of samples kept under refrigeration conditions (0-1 o ), and examined periodically under different analytic method criteria. Life span for the appearance characteristic reaches the acceptability limit of 3, after 11 days for control samples, and 16 and 13 days for samples radiated at 1 and 2 kGy. Smell of control samples was accepted only until the 13 th day while samples radiated at 1 and 2 kGy went beyond this level, reaching 19 and 17 days respectively. In the same way, life span for the flavor characteristic was extended to 19 and 20 days for samples radiated at 1 and 2 kGy, respectively, while control samples only reached 15 days. Control sample texture remained within acceptable limits until the 18 th day, whereas samples radiated at 1 and 2 kGy reached 21 and 17 days, respectively. Use of ph and nitrogen volatile bases were also evaluated as quality indicators. (authors)

  1. Physiological compensation for environmental acidification is limited in the deep-sea urchin Strongylocentrotus fragilis

    Science.gov (United States)

    Taylor, J. R.; Lovera, C.; Whaling, P. J.; Buck, K. R.; Pane, E. F.; Barry, J. P.

    2013-05-01

    Anthropogenic CO2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals - particularly, calcifiers - are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of hypercapnia and hypoxia on the deep-sea urchin Strongylocentrotus fragilis, during two long-term exposure experiments (1 month and 4 month) at three levels of reduced pH at in situ O2 levels of approx. 10% saturation, and also to control pH at 100% O2 saturation. During the first experiment, internal acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by reduced pH, due in part to low non-bicarbonate extracellular fluid buffering capacity. During the second experiment, longer-term effects of hypercapnia and variable O2 on locomotion, feeding, growth, and gonadosomatic index (GSI) were investigated; results show significant mortality and correlation of all measured parameters with environmental acidification at pH 6.6. Transient adverse effects on locomotion and feeding were seen at pH 7.2, without compromise of growth or GSI. Based on the expected changes in ocean pH and oxygen, results suggest extinction of S. fragilis in the eastern North Pacific is unlikely. Rather, we expect a shoaling and contraction of its bathymetric range.

  2. Genomic Characterization of the Evolutionary Potential of the Sea Urchin Strongylocentrotus droebachiensis Facing Ocean Acidification

    Science.gov (United States)

    Dorey, Narimane; Garfield, David A.; Stumpp, Meike; Dupont, Sam; Wray, Gregory A.

    2016-01-01

    Abstract Ocean acidification (OA) is increasing due to anthropogenic CO2 emissions and poses a threat to marine species and communities worldwide. To better project the effects of acidification on organisms’ health and persistence, an understanding is needed of the 1) mechanisms underlying developmental and physiological tolerance and 2) potential populations have for rapid evolutionary adaptation. This is especially challenging in nonmodel species where targeted assays of metabolism and stress physiology may not be available or economical for large-scale assessments of genetic constraints. We used mRNA sequencing and a quantitative genetics breeding design to study mechanisms underlying genetic variability and tolerance to decreased seawater pH (-0.4 pH units) in larvae of the sea urchin Strongylocentrotus droebachiensis. We used a gene ontology-based approach to integrate expression profiles into indirect measures of cellular and biochemical traits underlying variation in larval performance (i.e., growth rates). Molecular responses to OA were complex, involving changes to several functions such as growth rates, cell division, metabolism, and immune activities. Surprisingly, the magnitude of pH effects on molecular traits tended to be small relative to variation attributable to segregating functional genetic variation in this species. We discuss how the application of transcriptomics and quantitative genetics approaches across diverse species can enrich our understanding of the biological impacts of climate change. PMID:28082601

  3. Shell Venster

    International Nuclear Information System (INIS)

    De Wit, P.; Looijesteijn, B.; Regeer, B.; Stip, B.

    1995-03-01

    In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles

  4. Elimination of vibrio cholerae El Tor, in scallops (Argopecten purpuratus) by gamma radiation and product organoleptic evaluation; Eliminacion de vibrio cholerae, El Tor, en conchas de abanico (Argopecten purpuratus) con el uso de radiacion gamma y evaluacion sensorial del producto

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Z [Instituto Peruano de Energia Nuclear, Lima (Peru); Bernuy, B [Universidad Nacional Agraria la Molina, Lima (Peru); Vivanco, M [Universidad Nacional Federico Villarreal, Lima (Peru); Kahn, G [Universidad Nacional Agraria de la Selva, Pucallpa (Peru)

    1999-03-01

    V. cholerae D{sub 10} value in scallops (Argopecten purpuratus) was determined in vivo. D{sub 10} was found to be 0,143 kGy, requiring therefore the application of 8D in scallops, equivalent to a 1,14 kGy dose, the optimal dose for life span extension of samples kept under refrigeration conditions (0-1{sup o}), and examined periodically under different analytic method criteria. Life span for the appearance characteristic reaches the acceptability limit of 3, after 11 days for control samples, and 16 and 13 days for samples radiated at 1 and 2 kGy. Smell of control samples was accepted only until the 13{sup th} day while samples radiated at 1 and 2 kGy went beyond this level, reaching 19 and 17 days respectively. In the same way, life span for the flavor characteristic was extended to 19 and 20 days for samples radiated at 1 and 2 kGy, respectively, while control samples only reached 15 days. Control sample texture remained within acceptable limits until the 18{sup th} day, whereas samples radiated at 1 and 2 kGy reached 21 and 17 days, respectively. Use of ph and nitrogen volatile bases were also evaluated as quality indicators. (authors) 14 refs., 3 figs., 3 tabs., 1 ill.

  5. Importance-truncated shell model for multi-shell valence spaces

    Energy Technology Data Exchange (ETDEWEB)

    Stumpf, Christina; Vobig, Klaus; Roth, Robert [Institut fuer Kernphysik, TU Darmstadt (Germany)

    2016-07-01

    The valence-space shell model is one of the work horses in nuclear structure theory. In traditional applications, shell-model calculations are carried out using effective interactions constructed in a phenomenological framework for rather small valence spaces, typically spanned by one major shell. We improve on this traditional approach addressing two main aspects. First, we use new effective interactions derived in an ab initio approach and, thus, establish a connection to the underlying nuclear interaction providing access to single- and multi-shell valence spaces. Second, we extend the shell model to larger valence spaces by applying an importance-truncation scheme based on a perturbative importance measure. In this way, we reduce the model space to the relevant basis states for the description of a few target eigenstates and solve the eigenvalue problem in this physics-driven truncated model space. In particular multi-shell valence spaces are not tractable otherwise. We combine the importance-truncated shell model with refined extrapolation schemes to approximately recover the exact result. We present first results obtained in the importance-truncated shell model with the newly derived ab initio effective interactions for multi-shell valence spaces, e.g., the sdpf shell.

  6. Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development.

    Science.gov (United States)

    Mao, Chai-An; Agca, Cavit; Mocko-Strand, Julie A; Wang, Jing; Ullrich-Lüter, Esther; Pan, Ping; Wang, Steven W; Arnone, Maria Ina; Frishman, Laura J; Klein, William H

    2016-03-16

    Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures. © 2016 The Authors.

  7. Dynamic evolution of toll-like receptor multigene families in echinoderms

    Directory of Open Access Journals (Sweden)

    Katherine M Buckley

    2012-06-01

    Full Text Available The genome of the purple sea urchin, Strongylocentrotus purpuratus, was the first to be sequenced from a long-lived large invertebrate. Analysis of this genome uncovered a surprisingly complex immune system in which the moderately sized sets of pattern recognition receptors that form the core of vertebrate innate immunity are encoded in large multigene families. The sea urchin genome contains 253 Toll-like receptor (TLR genes, more than 200 Nod-like receptors and 1095 scavenger receptor cysteine-rich domains, a ten-fold expansion relative to vertebrates. Given their stereotypic structure and simple intron-exon architecture, the TLRs are the most tractable of these families for more detailed analysis. An immune defense role for these receptors is suggested by their sequence diversity and expression in immunologically active tissues, including phagocytes. This complexity of the sea urchin TLR multigene families largely derives from expansions that are independent of those in vertebrates and protostomes, although a small family of TLRs with structure similar to that of Drosophila Toll likely originated in an ancient eumetazoan ancestor. Several other invertebrate deuterostome genomes have been sequenced, including the cephalochordate, Branchiostoma floridae and the sea urchin Lytechinus variegatus, as well as partial sequences from two other sea urchin species. Here, we present an analysis of the invertebrate deuterostome TLRs with emphasis on the echinoderms. Representatives of most of the S. purpuratus TLR subfamilies and homologs of the protostome-like sequences are found in L. variegatus. The phylogeny of these genes within sea urchins highlights lineage-specific expansions at higher resolution than is evident at the phylum level. These analyses identify quickly evolving TLR subfamilies that are likely to have novel functions and other, more stable, subfamilies that may function similarly to those of vertebrates.

  8. MicroShell Minimalist Shell for Xilinx Microprocessors

    Science.gov (United States)

    Werne, Thomas A.

    2011-01-01

    MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is

  9. Oxidative Damage and Cellular Defense Mechanisms in Sea Urchin Models of Aging

    Science.gov (United States)

    Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

    2013-01-01

    The free radical or oxidative stress theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging due to the existence of species with tremendously different natural life spans including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate lifespan. Levels of protein carbonyls and 4-hydroxynonenal (HNE) measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age-pigment lipofuscin measured in muscle, nerve and esophagus, increased with age however it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species, however further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. PMID:23707327

  10. Parental exposure to heavy fuel oil induces developmental toxicity in offspring of the sea urchin Strongylocentrotus intermedius.

    Science.gov (United States)

    Duan, Meina; Xiong, Deqi; Yang, Mengye; Xiong, Yijun; Ding, Guanghui

    2018-05-03

    The present study investigated the toxic effects of parental (maternal/paternal) exposure to heavy fuel oil (HFO) on the adult reproductive state, gamete quality and development of the offspring of the sea urchin Strongylocentrotus intermedius. Adult sea urchins were exposed to effluents from HFO-oiled gravel columns for 7 days to simulate an oil-contaminated gravel shore, and then gametes of adult sea urchins were used to produce embryos to determine developmental toxicity. For adult sea urchins, no significant difference in the somatic size and weight was found between the various oil loadings tested, while the gonad weight and gonad index were significantly decreased at higher oil loadings. The spawning ability of adults and fecundity of females significantly decreased. For gametes, no effect was observed on the egg size and fertilization success in any of the groups. However, a significant increase in the percentage of anomalies in the offspring was observed and then quantified by an integrative toxicity index (ITI) at 24 and 48 h post fertilization. The offspring from exposed parents showed higher ITI values with more malformed embryos. The results confirmed that parental exposure to HFO can cause adverse effects on the offspring and consequently affect the recruitment and population maintenance of sea urchins. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Production, characterization and application of monoclonal antibodies to the coelomocytes of sea urchin Strongylocentrotus intermedius.

    Science.gov (United States)

    Wang, Yinan; Meng, Shaodong; Zhang, Jialin; Ding, Jun; Li, Qiang

    2018-04-01

    Sea urchin is one of marine animals with high economic and great scientific research values. Axial organ is a glandular organ that has been presumed as coelomocytes origin site. In this paper, two monoclonal antibodies (3G10 and 6B3) against coelomocytes of sea urchin Strongylocentrotus intermedius were developed by hybridoma technique. The mAbs were characterized by indirect immunofluorescence assay test (IIFAT), flow cytometry (FCM) and western blot assay. Results showed that mAb 3G10 recognized a protein of a molecular weight of 17 kDa in the spherule cells, while mAb 6B3 reacted with a protein of a molecular weight of 35 kDa in the phagocytes. Furthermore, specificity analysis revealed that the two mAbs could react with the coelomocytes of sea urchin S. nudus and Hemicentrotus pulcherrimus, but not with those of other common echinoderms including sea cucumber Apostichopus japonicus and starfish Asterias rollestoni. To determine whether the coelomocytes exist in the axial organ of sea urchin, the IIFAT assays were carried out based on the two mAbs. Result showed that positive fluorescence signals were distributed in the organ. It was revealed that the axial organ was rich in coelomocytes, which suggests that the organ may play as a producing source or reservoir in the ontogenesis of coelomocytes of sea urchin. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Optical properties of core-shell and multi-shell nanorods

    Science.gov (United States)

    Mokkath, Junais Habeeb; Shehata, Nader

    2018-05-01

    We report a first-principles time dependent density functional theory study of the optical response modulations in bimetallic core-shell (Na@Al and Al@Na) and multi-shell (Al@Na@Al@Na and Na@Al@Na@Al: concentric shells of Al and Na alternate) nanorods. All of the core-shell and multi-shell configurations display highly enhanced absorption intensity with respect to the pure Al and Na nanorods, showing sensitivity to both composition and chemical ordering. Remarkably large spectral intensity enhancements were found in a couple of core-shell configurations, indicative that optical response averaging based on the individual components can not be considered as true as always in the case of bimetallic core-shell nanorods. We believe that our theoretical results would be useful in promising applications depending on Aluminum-based plasmonic materials such as solar cells and sensors.

  13. Deadenylase depletion protects inherited mRNAs in primordial germ cells.

    Science.gov (United States)

    Swartz, S Zachary; Reich, Adrian M; Oulhen, Nathalie; Raz, Tal; Milos, Patrice M; Campanale, Joseph P; Hamdoun, Amro; Wessel, Gary M

    2014-08-01

    A crucial event in animal development is the specification of primordial germ cells (PGCs), which become the stem cells that create sperm and eggs. How PGCs are created provides a valuable paradigm for understanding stem cells in general. We find that the PGCs of the sea urchin Strongylocentrotus purpuratus exhibit broad transcriptional repression, yet enrichment for a set of inherited mRNAs. Enrichment of several germline determinants in the PGCs requires the RNA-binding protein Nanos to target the transcript that encodes CNOT6, a deadenylase, for degradation in the PGCs, thereby creating a stable environment for RNA. Misexpression of CNOT6 in the PGCs results in their failure to retain Seawi transcripts and Vasa protein. Conversely, broad knockdown of CNOT6 expands the domain of Seawi RNA as well as exogenous reporters. Thus, Nanos-dependent spatially restricted CNOT6 differential expression is used to selectively localize germline RNAs to the PGCs. Our findings support a 'time capsule' model of germline determination, whereby the PGCs are insulated from differentiation by retaining the molecular characteristics of the totipotent egg and early embryo. © 2014. Published by The Company of Biologists Ltd.

  14. Core-shell microspheres with porous nanostructured shells for liquid chromatography.

    Science.gov (United States)

    Ahmed, Adham; Skinley, Kevin; Herodotou, Stephanie; Zhang, Haifei

    2018-01-01

    The development of new stationary phases has been the key aspect for fast and efficient high-performance liquid chromatography separation with relatively low backpressure. Core-shell particles, with a solid core and porous shell, have been extensively investigated and commercially manufactured in the last decade. The excellent performance of core-shell particles columns has been recorded for a wide range of analytes, covering small and large molecules, neutral and ionic (acidic and basic), biomolecules and metabolites. In this review, we first introduce the advance and advantages of core-shell particles (or more widely known as superficially porous particles) against non-porous particles and fully porous particles. This is followed by the detailed description of various methods used to fabricate core-shell particles. We then discuss the applications of common silica core-shell particles (mostly commercially manufactured), spheres-on-sphere particles and core-shell particles with a non-silica shell. This review concludes with a summary and perspective on the development of stationary phase materials for high-performance liquid chromatography applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Hi shells, supershells, shell-like objects, and ''worms''

    International Nuclear Information System (INIS)

    Heiles, C.

    1984-01-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10 0 . We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo

  16. Crecimiento y producción somática de la concha de abanico (Argopecten purpuratus) en Bahía Independencia, Pisco (Perú) comparados entre eventos El Niño y La Niña

    OpenAIRE

    Tarazona, Juan; Espinoza, Roberto; Solís, Marco; Arntz, Wolf

    2007-01-01

    Argopecten purpuratus es el marisco de mayor importancia económica en la costa central del Perú, por su elevado volumen de extracción en la pesca artesanal. En los últimos años se ha incrementado la información sobre su stock, estructura poblacional y cambios en el tiempo (reclutamiento, reproducción, etc.). Sin embargo, aún se desconocen algunos aspectos de su dinámica poblacional ante la presencia de la Oscilación Sureña El Niño (ENOS). En el presente trabajo se hace una comparación de algu...

  17. Free vibration analysis of delaminated composite shells using different shell theories

    International Nuclear Information System (INIS)

    Nanda, Namita; Sahu, S.K.

    2012-01-01

    Free vibration response of laminated composite shells with delamination is presented using the finite element method based on first order shear deformation theory. The shell theory used is the extension of dynamic, shear deformable theory according to the Sanders' first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. An eight-noded C 0 continuity, isoparametric quadrilateral element with five degrees of freedom per node is used in the formulation. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. The natural frequencies of the delaminated cylindrical (CYL), spherical (SPH) and hyperbolic paraboloid (HYP) shells are determined by using the above mentioned shell theories, namely Sanders', Love's, and Donnell's. The validity of the present approach is established by comparing the authors' results with those available in the literature. Additional studies on free vibration response of CYL, SPH and HYP shells are conducted to assess the effects of delamination size and number of layers considering all three shell theories. It is shown that shell theories according to Sanders and Love always predict practically identical frequencies. Donnell's theory gives reliable results only for shallow shells. Moreover, the natural frequency is found to be very sensitive to delamination size and number of layers in the shell.

  18. Composted oyster shell as lime fertilizer is more effective than fresh oyster shell.

    Science.gov (United States)

    Lee, Young Han; Islam, Shah Md Asraful; Hong, Sun Joo; Cho, Kye Man; Math, Renukaradhya K; Heo, Jae Young; Kim, Hoon; Yun, Han Dae

    2010-01-01

    Physio-chemical changes in oyster shell were examined, and fresh and composted oyster shell meals were compared as lime fertilizers in soybean cultivation. Structural changes in oyster shell were observed by AFM and FE-SEM. We found that grains of the oyster shell surface became smoother and smaller over time. FT-IR analysis indicated the degradation of a chitin-like compound of oyster shell. In chemical analysis, pH (12.3+/-0.24), electrical conductivity (4.1+/-0.24 dS m(-1)), and alkaline powder (53.3+/-1.12%) were highest in commercial lime. Besides, pH was higher in composted oyster shell meal (9.9+/-0.53) than in fresh oyster shell meal (8.4+/-0.32). The highest organic matter (1.1+/-0.08%), NaCl (0.54+/-0.03%), and moisture (15.1+/-1.95%) contents were found in fresh oyster shell meal. A significant higher yield of soybean (1.33 t ha(-1)) was obtained by applying composted oyster shell meal (a 21% higher yield than with fresh oyster shell meal). Thus composting of oyster shell increases the utility of oyster shell as a liming material for crop cultivation.

  19. On the core-mass-shell-luminosity relation for shell-burning stars

    International Nuclear Information System (INIS)

    Jeffery, C.S.; Saint Andrews Univ.

    1988-01-01

    Core-mass-shell-luminosity relations for several types of shell-burning star have been calculated using simultaneous differential equations derived from simple homology approximations. The principal objective of obtaining a mass-luminosity relation for helium giants was achieved. This relation gives substantially higher luminosities than the equivalent relation for H-shell stars with core masses greater than 1 solar mass. The algorithm for calculating mass-luminosity relations in this fashion was investigated in detail. Most of the assumptions regarding the physics in the shell do not play a critical role in determining the core-mass-shell-luminosity relation. The behaviour of the core-mass-core-radius relation for a growing degenerate core as a single unique function of mass and growth rate needs to be defined before a single core-mass-shell-luminosity relation for all H-shell stars can be obtained directly from the homology approximations. (author)

  20. Variation in Orthologous Shell-Forming Proteins Contribute to Molluscan Shell Diversity.

    Science.gov (United States)

    Jackson, Daniel J; Reim, Laurin; Randow, Clemens; Cerveau, Nicolas; Degnan, Bernard M; Fleck, Claudia

    2017-11-01

    Despite the evolutionary success and ancient heritage of the molluscan shell, little is known about the molecular details of its formation, evolutionary origins, or the interactions between the material properties of the shell and its organic constituents. In contrast to this dearth of information, a growing collection of molluscan shell-forming proteomes and transcriptomes suggest they are comprised of both deeply conserved, and lineage specific elements. Analyses of these sequence data sets have suggested that mechanisms such as exon shuffling, gene co-option, and gene family expansion facilitated the rapid evolution of shell-forming proteomes and supported the diversification of this phylum specific structure. In order to further investigate and test these ideas we have examined the molecular features and spatial expression patterns of two shell-forming genes (Lustrin and ML1A2) and coupled these observations with materials properties measurements of shells from a group of closely related gastropods (abalone). We find that the prominent "GS" domain of Lustrin, a domain believed to confer elastomeric properties to the shell, varies significantly in length between the species we investigated. Furthermore, the spatial expression patterns of Lustrin and ML1A2 also vary significantly between species, suggesting that both protein architecture, and the regulation of spatial gene expression patterns, are important drivers of molluscan shell evolution. Variation in these molecular features might relate to certain materials properties of the shells of these species. These insights reveal an important and underappreciated source of variation within shell-forming proteomes that must contribute to the diversity of molluscan shell phenotypes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  1. Off-shell CHY amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Lam, C.S., E-mail: Lam@physics.mcgill.ca [Department of Physics, McGill University, Montreal, Q.C., H3A 2T8 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Yao, York-Peng, E-mail: yyao@umich.edu [Department of Physics, The University of Michigan Ann Arbor, MI 48109 (United States)

    2016-06-15

    The Cachazo–He–Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.

  2. Dossier Shell Eco-Marathon; Dossier Shell Eco-Marathon

    Energy Technology Data Exchange (ETDEWEB)

    Matla, P.

    2012-05-15

    Three articles address subjects concerning the annual race with highly energy efficient cars: the Shell Eco-Marathon. [Dutch] In 3 artikelen wordt aandacht besteed aan de ontwerpen voor de jaarlijkse race met superzuinige auto's, de Shell Eco-Marathon.

  3. Dominant thermogravimetric signatures of lignin in cashew shell as compared to cashew shell cake.

    Science.gov (United States)

    Gangil, Sandip

    2014-03-01

    Dominant thermogravimetric signatures related to lignin were observed in cashew shell as compared to these signatures in cashew shell cake. The phenomenon of weakening of lignin from cashew shell to cashew shell cake was explained on the basis of changes in the activation energies. The pertinent temperature regimes responsible for the release of different constituents of both the bio-materials were identified and compared. The activation energies of cashew shell and cashew shell cake were compared using Kissinger-Akahira-Sunose method. Thermogravimetric profiling of cashew shell and cashew shell cake indicated that these were different kinds of bio-materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Shell-like structures

    CERN Document Server

    Altenbach, Holm

    2011-01-01

    In this volume, scientists and researchers from industry discuss the new trends in simulation and computing shell-like structures. The focus is put on the following problems: new theories (based on two-dimensional field equations but describing non-classical effects), new constitutive equations (for materials like sandwiches, foams, etc. and which can be combined with the two-dimensional shell equations), complex structures (folded, branching and/or self intersecting shell structures, etc.) and shell-like structures on different scales (for example: nano-tubes) or very thin structures (similar

  5. Lipofuscin-like pigment in gonads of Sea Urchin Strongylocentrotus intermedius as a potential biomarker of marine pollution: a field study.

    Science.gov (United States)

    Vaschenko, Marina A; Zhadan, Peter M; Aminin, Dmitry L; Almyashova, Tatyana N

    2012-05-01

    Accumulation of lipofuscin-like pigments (LLPs) has been shown to be an appropriate index of both age and stress in some aquatic invertebrates. In the present study, LLP was quantified by measuring its autofluorescence intensity (ex 450 nm/em 512 nm) in nutritive phagocytes (NPs) of sea urchins Strongylocentrotus intermedius inhabiting polluted and relatively clean areas of Japan Sea. To avoid variations in LLP content related to sea urchin reproductive condition, only developing gonads with acini occupied mostly by NPs were used for LLP quantification as well as semiquantitative histopathological analysis. LLP concentrations ranged from 0.0 to 4.57 ± 0.53% area fraction in female gonads and from 0.0 to 4.61 ± 0.35% in male gonads. The presence of specimens with extremely high LLP concentrations (>1.5%) in all examined samples, including specimens from the reference station, as well as the absence of strong correlations between LLP concentrations and several parameters related to pollution (heavy-metal concentrations in sea urchin gonads and concentrations of heavy metals, DDT, hexachlorocyclohexane, and total petroleum hydrocarbons in sediments), allow us to conclude that LLP content in sea urchin NPs can not be used as a biomarker in marine pollution monitoring.

  6. Extensions to a nonlinear finite-element axisymmetric shell model based on Reissner's shell theory

    International Nuclear Information System (INIS)

    Cook, W.A.

    1981-01-01

    Extensions to shell analysis not usually associated with shell theory are described in this paper. These extensions involve thick shells, nonlinear materials, a linear normal stress approximation, and a changing shell thickness. A finite element shell-of-revolution model has been developed to analyze nuclear material shipping containers under severe impact conditions. To establish the limits for this shell model, the basic assumptions used in its development were studied; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress

  7. Isogeometric shell formulation based on a classical shell model

    KAUST Repository

    Niemi, Antti

    2012-09-04

    This paper constitutes the first steps in our work concerning isogeometric shell analysis. An isogeometric shell model of the Reissner-Mindlin type is introduced and a study of its accuracy in the classical pinched cylinder benchmark problem presented. In contrast to earlier works [1,2,3,4], the formulation is based on a shell model where the displacement, strain and stress fields are defined in terms of a curvilinear coordinate system arising from the NURBS description of the shell middle surface. The isogeometric shell formulation is implemented using the PetIGA and igakit software packages developed by the authors. The igakit package is a Python package used to generate NURBS representations of geometries that can be utilised by the PetIGA finite element framework. The latter utilises data structures and routines of the portable, extensible toolkit for scientific computation (PETSc), [5,6]. The current shell implementation is valid for static, linear problems only, but the software package is well suited for future extensions to geometrically and materially nonlinear regime as well as to dynamic problems. The accuracy of the approach in the pinched cylinder benchmark problem and present comparisons against the h-version of the finite element method with bilinear elements. Quadratic, cubic and quartic NURBS discretizations are compared against the isoparametric bilinear discretization introduced in [7]. The results show that the quadratic and cubic NURBS approximations exhibit notably slower convergence under uniform mesh refinement as the thickness decreases but the quartic approximation converges relatively quickly within the standard variational framework. The authors future work is concerned with building an isogeometric finite element method for modelling nonlinear structural response of thin-walled shells undergoing large rigid-body motions. The aim is to use the model in a aeroelastic framework for the simulation of flapping wings.

  8. Testing lagoonal sediments with early life stages of the copepod Acartia tonsa (Dana): An approach to assess sediment toxicity in the Venice Lagoon.

    Science.gov (United States)

    Picone, Marco; Bergamin, Martina; Delaney, Eugenia; Ghirardini, Annamaria Volpi; Kusk, Kresten Ole

    2018-01-01

    The early-life stages of development of the calanoid copepod Acartia tonsa from egg to copepodite I is proposed as an endpoint for assessing sediment toxicity by exposing newly released eggs directly onto the sediment-water interface. A preliminary study of 5 sediment samples collected in the lagoon of Venice highlighted that the larval development rate (LDR) and the early-life stages (ELS) mortality endpoints with A. tonsa are more sensitive than the standard amphipod mortality test; moreover LDR resulted in a more reliable endpoint than ELS mortality, due to the interference of the sediment with the recovery of unhatched eggs and dead larvae. The LDR data collected in a definitive study of 48 sediment samples from the Venice Lagoon has been analysed together with the preliminary data to evaluate the statistical performances of the bioassay (among replicate variance and minimum significant difference between samples and control) and to investigate the possible correlation with sediment chemistry and physical properties. The results showed that statistical performances of the LDR test with A. tonsa correspond with the outcomes of other tests applied to the sediment-water interface (Strongylocentrotus purpuratus embryotoxicity test), sediments (Neanthes arenaceodentata survival and growth test) and porewater (S. purpuratus); the LDR endpoint did, however, show a slightly higher variance as compared with other tests used in the Lagoon of Venice, such as 10-d amphipod lethality test and larval development with sea urchin and bivalves embryos. Sediment toxicity data highlighted the high sensitivity and the clear ability of the larval development to discriminate among sediments characterized by different levels of contamination. The data of the definitive study evidenced that inhibition of the larval development was not affected by grain-size and the organic carbon content of the sediment; in contrast, a strong correlation between inhibition of the larval development

  9. Axial complex and associated structures of the sea urchin Strongylocentrotus pallidus (Sars, G.O. 1871) (Echinodermata: Echinoidea).

    Science.gov (United States)

    Ezhova, Olga Vladimirovna; Malakhov, Vladimir Vasil'yevich; Egorova, Ekaterina Alekseevna

    2018-06-01

    Studies of echinoid microscopic anatomy over the last two centuries have created a number of inaccuracies and mistakes that have accumulated in the descriptions of the intricate organization of the coelomic system of Echinoidea. To clarify the situation, we reconstructed the axial complex and radial complex of the echinoid Strongylocentrotus pallidus. The water ring is located between the perivisceral coelom and the perioral coelom. The oral haemal ring lies between the coelothelia of the water-vascular, perivisceral, and perioral rings. The axial part of the axial organ communicates with the oral haemal ring in interradius CD, but the axial coelom does not form the axocoelomic perihaemal ring. The ventral intestinal haemal vessel originates from the oral haemal ring in radius A, and then branches into a network of capillaries, from which the dorsal intestinal vessel starts. The pericardial coelom envelopes the pericardial part of the axial organ, the lacunae of which communicate with the haemocoel of the body wall and with the axial part of the axial organ. The genital haemal ring and the dorsal intestinal vessel communicate with the axial organ. The genital coelom passes in the CD interradius on the side opposite to the hindgut. There is a somatocoelomic perihaemal ring, which sends a pair of coelomic outgrowths into each radius, accompanied by a radial haemal vessel in the oral part. The mistakes and inaccuracies of early descriptions of the echinoid axial complex are listed. The axial complex and associated structures of sea urchins are compared with other eleutherozoans. © 2018 Wiley Periodicals, Inc.

  10. Sobrevivencia y crecimiento de post-larvas de Argopecten purpuratus (Lamarck, 1819 en Bahía Inglesa, Chile: efectos del origen, distribución en la bahía y bacterioflora larval Postlarval survival and growth of Argopecten purpuratus (Lamarck,1819 in Bahia Inglesa, Chile: effects of origin, distribution in the bay and larval bacterioflora

    Directory of Open Access Journals (Sweden)

    RUBÉN E. AVENDAÑO

    2001-09-01

    Full Text Available Argopecten purpuratus es uno de los recursos marinos de mayor importancia comercial en Chile. Una de las etapas críticas en el cultivo de esta especie, es el traspaso de las post-larvas al medio natural, ya que durante este período se produce un significativo descenso en el número de post-larvas. Los factores que provocan estas bajas sobrevivencias pueden ser diversos, pero aún son desconocidos. En el presente estudio se evaluó la incidencia en la sobrevivencia y crecimiento de las variables origen de las larvas, distribución de los colectores en diferentes estaciones de Bahía Inglesa, III región (27° 03' 24" S, 70° 51' 30" O y los cambios en la bacterioflora asociadas a las post-larvas. Los organismos utilizados en el estudio fueron obtenidas desde los "hatcheries" de Cultivos Marinos Internacionales (III región y Cultivos Guayacán (IV región. Los resultados del estudio indican claramente que la ubicación y origen de las post-larvas en la bahía incide en la sobrevivencia de éstas. Sin embargo, el crecimiento no es afectado por las variables estudiadas (P Argopecten purpuratus is one of the most commercially important marine resources in Chile. One of the most critical steps in the massive culture of this species is the transference of postlarvae from hatchery production to the sea where significant mortality regularly occurs. The factors behind this low survival rate are probably diverse, and are as yet unknown. In the present study, postlarval survival and growth was observed as a function of origin of postlarvae, distribution of postlarvae in the bay, and microbial loading of the postlarvae. Survival rates were measured for different sites in Bahia Inglesa, Chile (27° 03' 24" S, 70° 51' 30" W as well as changes in the bacterioflora of the postlarvae. Postlarvae utilized in the study were obtained from Cultivos Marinos Internacionales (III Región and Cultivos Guayacan (IV Región. Results of the study clearly indicated that

  11. Molluscan shell colour.

    Science.gov (United States)

    Williams, Suzanne T

    2017-05-01

    The phylum Mollusca is highly speciose, and is the largest phylum in the marine realm. The great majority of molluscs are shelled, including nearly all bivalves, most gastropods and some cephalopods. The fabulous and diverse colours and patterns of molluscan shells are widely recognised and have been appreciated for hundreds of years by collectors and scientists alike. They serve taxonomists as characters that can be used to recognise and distinguish species, however their function for the animal is sometimes less clear and has been the focus of many ecological and evolutionary studies. Despite these studies, almost nothing is known about the evolution of colour in molluscan shells. This review summarises for the first time major findings of disparate studies relevant to the evolution of shell colour in Mollusca and discusses the importance of colour, including the effects of visual and non-visual selection, diet and abiotic factors. I also summarise the evidence for the heritability of shell colour in some taxa and recent efforts to understand the molecular mechanisms underpinning synthesis of shell colours. I describe some of the main shell pigments found in Mollusca (carotenoids, melanin and tetrapyrroles, including porphyrins and bile pigments), and their durability in the fossil record. Finally I suggest that pigments appear to be distributed in a phylogenetically relevant manner and that the synthesis of colour is likely to be energetically costly. © 2016 Cambridge Philosophical Society.

  12. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    Directory of Open Access Journals (Sweden)

    Schilthuizen Menno

    2003-06-01

    Full Text Available Abstract Background Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored. Presentation of the hypothesis The hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species. Testing the hypothesis The first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy. Implications of the hypothesis If the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.

  13. Windows PowerShell 20 Bible

    CERN Document Server

    Lee, Thomas; Schill, Mark E; Tanasovski, Tome

    2011-01-01

    Here's the complete guide to Windows PowerShell 2.0 for administrators and developers Windows PowerShell is Microsoft's next-generation scripting and automation language. This comprehensive volume provides the background that IT administrators and developers need in order to start using PowerShell automation in exciting new ways. It explains what PowerShell is, how to use the language, and specific ways to apply PowerShell in various technologies. Windows PowerShell is Microsoft's standard automation tool and something that every Windows administrator will eventually have to understand; this b

  14. TWO-DIMENSIONAL APPROXIMATION OF EIGENVALUE PROBLEMS IN SHELL THEORY: FLEXURAL SHELLS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The eigenvalue problem for a thin linearly elastic shell, of thickness 2e, clamped along its lateral surface is considered. Under the geometric assumption on the middle surface of the shell that the space of inextensional displacements is non-trivial, the authors obtain, as ε→0,the eigenvalue problem for the two-dimensional"flexural shell"model if the dimension of the space is infinite. If the space is finite dimensional, the limits of the eigenvalues could belong to the spectra of both flexural and membrane shells. The method consists of rescaling the variables and studying the problem over a fixed domain. The principal difficulty lies in obtaining suitable a priori estimates for the scaled eigenvalues.

  15. Plasticity and trade-offs in physiological traits of intertidal mussels subjected to freshwater-induced environmental variation

    KAUST Repository

    Ramajo, L

    2016-05-17

    Environmental gradients play an important role in shaping geographic variability in coastal marine populations. Thus, the ability of organisms to cope with these changes will depend on their potential to acclimatize, or adapt, to these new environmental conditions. We investigated the spatial variability in biological responses shown by Perumytilus purpuratus mussels collected from 2 intertidal areas experiencing contrasting freshwater input influences (river-influenced vs. marine conditions). To highlight the role of plasticity and adaptive potential in biological responses, we performed a reciprocal-Transplant experiment and measured relevant phenotypic traits including mortality, growth, calcification, metabolism, and chemical composition of the shell periostra-cum. We determined that mussels exposed to river-influenced conditions had increased metabolic rates and reduced growth rates, as compared to mussels experiencing marine conditions (p > 0.05). While the energy investment strategies of the 2 local populations resulted in similar net calcification rates, these rates decreased significantly when mussels were transplanted to the river-influenced site. Stressful conditions at the river-influenced site were evidenced by decreased survivorship across treatments. Freshwater inputs modify the organic composition of the shell periostracum through a significant reduction in polysaccharides. Although our field experiment did not identify specific environmental factors underlying these contrasting phenotypic changes, the results imply that plasticity plays a strong role when P. purpuratus is exposed to some combination of natural (e.g. salinity) and anthropogenic influences (e.g. pollution), and that the lack of exposure to freshwater may promote less tolerant mussels with greater potential for local adaptation. © The authors 2016.

  16. Plasticity and trade-offs in physiological traits of intertidal mussels subjected to freshwater-induced environmental variation

    KAUST Repository

    Ramajo, L; Prado, L; Rodriguez-Navarro, AB; Lardies, MA; Duarte, Carlos M.; Lagos, NA

    2016-01-01

    Environmental gradients play an important role in shaping geographic variability in coastal marine populations. Thus, the ability of organisms to cope with these changes will depend on their potential to acclimatize, or adapt, to these new environmental conditions. We investigated the spatial variability in biological responses shown by Perumytilus purpuratus mussels collected from 2 intertidal areas experiencing contrasting freshwater input influences (river-influenced vs. marine conditions). To highlight the role of plasticity and adaptive potential in biological responses, we performed a reciprocal-Transplant experiment and measured relevant phenotypic traits including mortality, growth, calcification, metabolism, and chemical composition of the shell periostra-cum. We determined that mussels exposed to river-influenced conditions had increased metabolic rates and reduced growth rates, as compared to mussels experiencing marine conditions (p > 0.05). While the energy investment strategies of the 2 local populations resulted in similar net calcification rates, these rates decreased significantly when mussels were transplanted to the river-influenced site. Stressful conditions at the river-influenced site were evidenced by decreased survivorship across treatments. Freshwater inputs modify the organic composition of the shell periostracum through a significant reduction in polysaccharides. Although our field experiment did not identify specific environmental factors underlying these contrasting phenotypic changes, the results imply that plasticity plays a strong role when P. purpuratus is exposed to some combination of natural (e.g. salinity) and anthropogenic influences (e.g. pollution), and that the lack of exposure to freshwater may promote less tolerant mussels with greater potential for local adaptation. © The authors 2016.

  17. Revisiting chameleon gravity: Thin-shell and no-shell fields with appropriate boundary conditions

    International Nuclear Information System (INIS)

    Tamaki, Takashi; Tsujikawa, Shinji

    2008-01-01

    We derive analytic solutions of a chameleon scalar field φ that couples to a nonrelativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass m A inside of the body. The standard thin-shell field profile is recovered by taking the limit m A r c →∞, where r c is a radius of the body. We show the existence of ''no-shell'' solutions where the field is nearly frozen in the whole interior of the body, which does not necessarily correspond to the 'zero-shell' limit of thin-shell solutions. In the no-shell case, under the condition m A r c >>1, the effective coupling of φ with matter takes the same asymptotic form as that in the thin-shell case. We study experimental bounds coming from the violation of equivalence principle as well as solar-system tests for a number of models including f(R) gravity and find that the field is in either the thin-shell or the no-shell regime under such constraints, depending on the shape of scalar-field potentials. We also show that, for the consistency with local gravity constraints, the field at the center of the body needs to be extremely close to the value φ A at the extremum of an effective potential induced by the matter coupling.

  18. Transport comparison of multiwall carbon nanotubes by contacting outer shell and all shells.

    Science.gov (United States)

    Luo, Qiang; Cui, A-Juan; Zhang, Yi-Guang; Lu, Chao; Jin, Ai-Zi; Yang, Hai-Fang; Gu, Chang-Zhi

    2010-11-01

    Carbon nanotubes, particularly multiwall carbon nanotubes (MWCNTs) can serve as interconnects in nanoelectronic devices and integrated circuits because of their extremely large current-carrying capacity. Many experimental results about the transport properties of individual MWCNTs by contacting outer shell or all shells have been reported. In this work, a compatible method with integrated circuit manufacturing process was presented to compare the transport property of an individual multiwall carbon nanotube (MWCNT) by contacting outer shell only and all shells successively. First of the Ti/Au electrodes contacting outer shell only were fabricated onto the nanotube through the sequence of electron beam lithography (EBL) patterning, metal deposition and lift-off process. After the characterization of its transport property, focused ion beam (FIB) was used to drill holes through the same nanotube at the as-deposited electrodes. Then new contact to the holes and electrodes were made by ion-induced deposition of tungsten from W(CO)6 precursor gas. The transport results indicated that the new contact to all shells can clear up the intershell resistance and the electrical conductance of the tube can be improved about 8 times compared to that of by contacting outer shell only.

  19. Shell report 2001; Les personnes, la planete, les profits. Shell rapport 2001

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    In 2001, Shell saw mixed results across the social, environmental and economic spectrum. In order to contribute to the sustainable development, the Group is on track towards meeting its target to reduce greenhouse gas emissions to 10 % below 1990 levels by the end of 2002, although there was a significant increase in spill volumes and greenhouse gas emissions rose. Shell has articulated the business case and defined seven principles of sustainable development for use across the Group in business plans and daily operations: generating robust profitability; delivering value to customers; protecting the environment; managing resources; respecting and safeguarding people; benefiting communities; and working with stakeholders. Key points from the Shell Report include: in the framework of Managing, an independent review of the Shell Nigeria Community Development programme and testing of a human rights assessment tool in Shell South Africa and the implementing of a new Diversity and Inclusiveness Standard; in the framework of the economy the cost improvements of 5,1 billion dollars, ahead of target, the second highest earnings ever in difficult market conditions and the election of Shell top brand for fifth year running by motorists; in the framework of the Social, the safety performance, the avoidance of 100 contracts for incompatibility with Shell Business Principles; in the framework of the Environment, the publication of the Fresh water usage report for the first time, the Greenhouse gas emissions, the increase of spills as a result of a small number of incidents including a pipeline rupture in Nigeria and a well blow out in Oman. The economic, environmental and social data of the Shell Report are externally verified. (A.L.B.)

  20. Local shell-to-shell energy transfer via nonlocal interactions in fluid ...

    Indian Academy of Sciences (India)

    However, the shell-to-shell energy transfer rate is found to be local and forward. .... interaction was strong, but the energy exchange occurred predominantly between ..... The wave-number range considered is in the inverse cascade regime.

  1. Multi-shelled ZnCo2O4 yolk-shell spheres for high-performance acetone gas sensor

    Science.gov (United States)

    Xiong, Ya; Zhu, Zongye; Ding, Degong; Lu, Wenbo; Xue, Qingzhong

    2018-06-01

    In the present study, multi-shelled ZnCo2O4 yolk-shell spheres have been successfully prepared by using carbonaceous microspheres as templates. It is found that the multi-shelled ZnCo2O4 yolk-shell spheres based sensor shows optimal sensing performances (response value of 38.2, response/recovery time of 19 s/71 s) toward 500 ppm acetone at 200 °C. In addition, this sensor exhibits a low detection limit of 0.5 ppm acetone (response value of 1.36) and a good selectivity toward hydrogen, methane, ethanol, ammonia and carbon dioxide. Furthermore, it is demonstrated that acetone gas response of multi-shelled ZnCo2O4 yolk-shell spheres is significantly better than that of ZnCo2O4 nanotubes and ZnCo2O4 nanosheets. High acetone response of the multi-shelled ZnCo2O4 yolk-shell spheres is attributed to the enhanced gas accessibility of the multi-shell morphology caused by the small crystalline size and high specific surface area while the short response/recovery time is mainly related to the rapid gas diffusion determined by the highly porous structure. Our work puts forward an exciting opportunity in designing various yolk-shelled structures for multipurpose applications.

  2. Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions.

    Science.gov (United States)

    Neville, Frances; Moreno-Atanasio, Roberto

    2018-01-01

    We present a Discrete Element study of the behavior of magnetic core-shell particles in which the properties of the core and the shell are explicitly defined. Particle cores were considered to be made of pure iron and thus possessed ferromagnetic properties, while particle shells were considered to be made of silica. Core sizes ranged between 0.5 and 4.0 μm with the actual particle size of the core-shell particles in the range between 0.6 and 21 μm. The magnetic cores were considered to have a magnetization of one tenth of the saturation magnetization of iron. This study aimed to understand how the thickness of the shell hinders the formation of particle chains. Chain formation was studied with different shell thicknesses and particle sizes in the presence and absence of an electrical double layer force in order to investigate the effect of surface charge density on the magnetic core-shell particle interactions. For core sizes of 0.5 and 4.0 μm the relative shell thicknesses needed to hinder the aggregation process were approximately 0.4 and 0.6 respectively, indicating that larger core sizes are detrimental to be used in applications in which no flocculation is needed. In addition, the presence of an electrical double layer, for values of surface charge density of less than 20 mC/m 2 , could stop the contact between particles without hindering their vertical alignment. Only when the shell thickness was considerably larger, was the electrical double layer able to contribute to the full disruption of the magnetic flocculation process.

  3. Interelectron correlations in photoionization of outer shells near inner shell thresholds

    International Nuclear Information System (INIS)

    Amusia, M Ya; Chernysheva, L V; Drukarev, E G

    2015-01-01

    We have studied the role of virtual excitations of inner shells upon outer shell photoionization. The calculations were performed in the frames of the Random Phase Approximation with Exchange (RPAE) and its generalized version GRPAE that take into account variation of the atomic field due to electron elimination and the inner vacancies decay. We apply both analytic approximation and numeric computations. The results are presented for 3p electrons in Ar and for 4d-electrons in Pd near inner shells thresholds. The effect considered proved to be quite noticeable. (paper)

  4. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

    2011-01-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells

  5. Adsorption of volatile organic compounds by pecan shell- and almond shell-based granular activated carbons.

    Science.gov (United States)

    Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

    2003-11-01

    The objective of this research was to determine the effectiveness of using pecan and almond shell-based granular activated carbons (GACs) in the adsorption of volatile organic compounds (VOCs) of health concern and known toxic compounds (such as bromo-dichloromethane, benzene, carbon tetrachloride, 1,1,1-trichloromethane, chloroform, and 1,1-dichloromethane) compared to the adsorption efficiency of commercially used carbons (such as Filtrasorb 200, Calgon GRC-20, and Waterlinks 206C AW) in simulated test medium. The pecan shell-based GACs were activated using steam, carbon dioxide or phosphoric acid. An almond shell-based GAC was activated with phosphoric acid. Our results indicated that steam- or carbon dioxide-activated pecan shell carbons were superior in total VOC adsorption to phosphoric acid-activated pecan shell or almond shell carbons, inferring that the method of activation selected for the preparation of activated carbons affected the adsorption of VOCs and hence are factors to be considered in any adsorption process. The steam-activated, pecan shell carbon adsorbed more total VOCs than the other experimental carbons and had an adsorption profile similar to the two coconut shell-based commercial carbons, but had greater adsorption than the coal-based commercial carbon. All the carbons studied adsorbed benzene more effectively than the other organics. Pecan shell, steam-activated and acid-activated GACs showed higher adsorption of 1,1,1-trichloroethane than the other carbons studied. Multivariate analysis was conducted to group experimental carbons and commercial carbons based on their physical, chemical, and adsorptive properties. The results of the analysis conclude that steam-activated and acid-activated pecan shell carbons clustered together with coal-based and coconut shell-based commercial carbons, thus inferring that these experimental carbons could potentially be used as alternative sources for VOC adsorption in an aqueous environment.

  6. Instant Windows PowerShell

    CERN Document Server

    Menon, Vinith

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. A practical, hands-on tutorial approach that explores the concepts of PowerShell in a friendly manner, taking an adhoc approach to each topic.If you are an administrator who is new to PowerShell or are looking to get a good grounding in these new features, this book is ideal for you. It's assumed that you will have some experience in PowerShell and Windows Server, as well being familiar with the PowerShell command-line.

  7. Coal option. [Shell Co

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    This paper notes the necessity of developing an international coal trade on a very large scale. The role of Shell in the coal industry is examined; the regions in which Shell companies are most active are Australia, Southern Africa, Indonesia; Europe and North America. Research is being carried out on marketing and transportation, especially via slurry pipelines; coal-oil emulsions; briquets; fluidized-bed combustion; recovery of coal from potential waste material; upgrading of low-rank coals; unconventional forms of mining; coal conversion (the Shell/Koppers high-pressure coal gasification process). Techniques for cleaning flue gas (the Shell Flue Gas Desulfurization process) are being examined.

  8. Nuclear shell theory

    CERN Document Server

    de-Shalit, Amos; Massey, H S W

    1963-01-01

    Nuclear Shell Theory is a comprehensive textbook dealing with modern methods of the nuclear shell model. This book deals with the mathematical theory of a system of Fermions in a central field. It is divided into three parts. Part I discusses the single particle shell model. The second part focuses on the tensor algebra, two-particle systems. The last part covers three or more particle systems. Chapters on wave functions in a central field, tensor fields, and the m-Scheme are also presented. Physicists, graduate students, and teachers of nuclear physics will find the book invaluable.

  9. Wrinkling of Pressurized Elastic Shells

    KAUST Repository

    Vella, Dominic

    2011-10-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.

  10. Genetic diversity of the NE Atlantic sea urchin Strongylocentrotus droebachiensis unveils chaotic genetic patchiness possibly linked to local selective pressure.

    Science.gov (United States)

    Norderhaug, K M; Anglès d'Auriac, M B; Fagerli, C W; Gundersen, H; Christie, H; Dahl, K; Hobæk, A

    We compared the genetic differentiation in the green sea urchin Strongylocentrotus droebachiensis from discrete populations on the NE Atlantic coast. By using eight recently developed microsatellite markers, genetic structure was compared between populations from the Danish Strait in the south to the Barents Sea in the north (56-79°N). Urchins are spread by pelagic larvae and may be transported long distances by northwards-going ocean currents. Two main superimposed patterns were identified. The first showed a subtle but significant genetic differentiation from the southernmost to the northernmost of the studied populations and could be explained by an isolation by distance model. The second pattern included two coastal populations in mid-Norway (65°N), NH and NS, as well as the northernmost population of continental Norway (71°N) FV. They showed a high degree of differentiation from all other populations. The explanation to the second pattern is most likely chaotic genetic patchiness caused by introgression from another species, S. pallidus, into S. droebachiensis resulting from selective pressure. Ongoing sea urchin collapse and kelp forests recovery are observed in the area of NH, NS and FV populations. High gene flow between populations spanning more than 22° in latitude suggests a high risk of new grazing events to occur rapidly in the future if conditions for sea urchins are favourable. On the other hand, the possibility of hybridization in association with collapsing populations may be used as an early warning indicator for monitoring purposes.

  11. Stability of charged thin shells

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2011-01-01

    In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.

  12. Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

    Directory of Open Access Journals (Sweden)

    Bartosz Bartosewicz

    2017-10-01

    Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

  13. Shell supports

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2004-01-01

    A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....

  14. A refined element-based Lagrangian shell element for geometrically nonlinear analysis of shell structures

    Directory of Open Access Journals (Sweden)

    Woo-Young Jung

    2015-04-01

    Full Text Available For the solution of geometrically nonlinear analysis of plates and shells, the formulation of a nonlinear nine-node refined first-order shear deformable element-based Lagrangian shell element is presented. Natural co-ordinate-based higher order transverse shear strains are used in present shell element. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Furthermore, a refined first-order shear deformation theory for thin and thick shells, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. To avoid difficulties resulting from large increments of the rotations, a scheme of attached reference system is used for the expression of rotations of shell normal. Numerical examples demonstrate that the present element behaves reasonably satisfactorily either for the linear or for geometrically nonlinear analysis of thin and thick plates and shells with large displacement but small strain. Especially, the nonlinear results of slit annular plates with various loads provided the benchmark to test the accuracy of related numerical solutions.

  15. Statistical Mechanics of Thin Spherical Shells

    Directory of Open Access Journals (Sweden)

    Andrej Košmrlj

    2017-01-01

    Full Text Available We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells. In flat membranes with a shear modulus, thermal fluctuations increase the bending rigidity and reduce the in-plane elastic moduli in a scale-dependent fashion. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes, and the local out-of-plane undulations leads to novel phenomena. In spherical shells, thermal fluctuations produce a radius-dependent negative effective surface tension, equivalent to applying an inward external pressure. By adapting renormalization group calculations to allow for a spherical background curvature, we show that while small spherical shells are stable, sufficiently large shells are crushed by this thermally generated “pressure.” Such shells can be stabilized by an outward osmotic pressure, but the effective shell size grows nonlinearly with increasing outward pressure, with the same universal power-law exponent that characterizes the response of fluctuating flat membranes to a uniform tension.

  16. Temporal structures in shell models

    DEFF Research Database (Denmark)

    Okkels, F.

    2001-01-01

    The intermittent dynamics of the turbulent Gledzer, Ohkitani, and Yamada shell-model is completely characterized by a single type of burstlike structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell...

  17. Expert system development (ESD) shell

    International Nuclear Information System (INIS)

    Padmini, S.; Diwakar, M.P.; Rathode, N.C.; Bairi, B.R.

    1991-01-01

    An Expert System Development (ESD) Shell design implementation is desribed in detail. The shell provides high-level generic facilities for Knowledge Representation (KR) and inferencing and tools for developing user interfaces. Powerful set of tools in the shell relieves much of the programming burden in the ES development. The shell is written in PROLOG under IBM PC/AT. KR facilities are based on two very powerful formalisms namely, frames and rules. Inference Engine (IE) draws most of its power from unification and backward reasoning strategy in PROLOG. This basic mechanism is enhanced further by incorporating both forward and backward chaining of rules and frame-based inferencing. Overall programming style integrates multiple paradigms including logic, object oriented, access-oriented and imperative programming. This permits ES designer a lot of flexibility in organizing inference control. Creation and maintainance of knowledge base is a major activity. The shell, therefore, provides number of facilities to simplify these tasks. Shell design also takes note of the fact that final success of any system depends on end-user satisfaction and hence provides features to build use-friendly interfaces. The shell also provides a set of interfacing predicates so that it can be embedded within any PROLOG program to incorporate functionalilty of the shell in the user program. (author). 10 refs., 8 figs

  18. Design aids for stiffened composite shells with cutouts

    CERN Document Server

    Sahoo, Sarmila

    2017-01-01

    This book focuses on the free vibrations of graphite-epoxy laminated composite stiffened shells with cutout both in terms of the natural frequencies and mode shapes. The dynamic analysis of shell structures, which may have complex geometry and arbitrary loading and boundary conditions, is solved efficiently by the finite element method, even including cutouts in shells. The results may be readily used by practicing engineers dealing with stiffened composite shells with cutouts. Several shell forms viz. cylindrical shell, hypar shell, conoidal shell, spherical shell, saddle shell, hyperbolic paraboloidal shell and elliptic paraboloidal shell are considered in the book. The dynamic characteristics of stiffened composite shells with cutout are described in terms of the natural frequency and mode shapes. The size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of cross-ply and angle-ply laminated composite shells. The effects of these parametric variat...

  19. Activated carbons prepared from hazelnut shells, walnut shells and peanut shells for high CO2 adsorption

    Directory of Open Access Journals (Sweden)

    Lewicka Katarzyna

    2017-06-01

    Full Text Available Research treats about producing activated carbons for CO2 capture from hazelnut shells (HN, walnut shells (WN and peanut shells (PN. Saturated solution of KOH was used as an activating agent in ratio 1:1. Samples were carbonized in the furnace in the range of temperatures 600°C–900°C. Properties of carbons were tested by N2 adsorption method, using BET equation, DFT method and volumetric CO2 adsorption method. With the increase of carbonization temperature specific surface area of studied samples increased. The largest surface area was calculated for samples carbonized at 900°C and the highest values of CO2 adsorption had samples: PN900 at 0°C (5.5 mmol/g and WN900 at 25°C (4.34 mmol/g. All of the samples had a well-developed microporous structure.

  20. Patterns of Mass Mortality among Rocky Shore Invertebrates across 100 km of Northeastern Pacific Coastline.

    Directory of Open Access Journals (Sweden)

    Laura J Jurgens

    Full Text Available Mass mortalities in natural populations, particularly those that leave few survivors over large spatial areas, may cause long-term ecological perturbations. Yet mass mortalities may remain undocumented or poorly described due to challenges in responding rapidly to unforeseen events, scarcity of baseline data, and difficulties in quantifying rare or patchily distributed species, especially in remote or marine systems. Better chronicling the geographic pattern and intensity of mass mortalities is especially critical in the face of global changes predicted to alter regional disturbance regimes. Here, we couple replicated post-mortality surveys with preceding long-term surveys and historical data to describe a rapid and severe mass mortality of rocky shore invertebrates along the north-central California coast of the northeastern Pacific Ocean. In late August 2011, formerly abundant intertidal populations of the purple sea urchin (Strongylocentrotus purpuratus, a well-known ecosystem engineer, and the predatory six-armed sea star (Leptasterias sp. were functionally extirpated from ~100 km of coastline. Other invertebrates, including the gumboot chiton (Cryptochiton stelleri the ochre sea star (Pisaster ochraceus, and subtidal populations of purple sea urchins also exhibited elevated mortality. The pattern and extent of mortality suggest the potential for long-term population, community, and ecosystem consequences, recovery from which may depend on the different dispersal abilities of the affected species.

  1. cDNA cloning, expression and immune function analysis of a novel Rac1 gene (AjRac1) in the sea cucumber Apostichopus japonicus.

    Science.gov (United States)

    Li, Kaiquan; Liu, Lin; Shang, Shengnan; Wang, Yi; Zhan, Yaoyao; Song, Jian; Zhang, Xiangxiang; Chang, Yaqing

    2017-10-01

    The ras-related C3 botulinum toxin substrate 1 (Rac1) belongs to Ras homolog (Rho) small GTPases subfamily. As an important molecular switch, Rac1 regulates various processes in the cell, especially in cellular immune response. With attempt to clarify characters and functions of Rac1 in sea cucumbers, full length cDNA of a Rac1 homolog in the sea cucumber Apostichopus japonicus (AjRac1) was cloned by transcriptome database mining and rapid amplification of cDNA ends (RACE) techniques. The open reading frame of AjRac1 is 579 bp encoding a protein with a length of 192 aa. Sequence analysis showed that AjRac1 is highly conserved as compared to those from other eukaryotic species. Phylogenetic analysis revealed that amino acid sequence of AjRac1 closely related to those from Strongylocentrotus purpuratus. Results of expression analysis showed that AjRac1 exhibited a relative high expression in blastula stage, adult coelomocytes and respiratory tree in A. japonicus. The transcription of AjRac1 in adult coelomocytes altered significantly at 4 h- and 12 h-after Vibrio splendidus infection, respectively, which indicated that AjRac1 involved in sea cucumber innate immunity. All data presented in this study will deepen our understanding of characterizations and immunological functions of Rac1 in sea cucumbers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Transcriptome analysis of the scleractinian coral Stylophora pistillata.

    Directory of Open Access Journals (Sweden)

    Sarit Karako-Lampert

    Full Text Available The principal architects of coral reefs are the scleractinian corals; these species are divided in two major clades referred to as "robust" and "complex" corals. Although the molecular diversity of the "complex" clade has received considerable attention, with several expressed sequence tag (EST libraries and a complete genome sequence having been constructed, the "robust" corals have received far less attention, despite the fact that robust corals have been prominent focal points for ecological and physiological studies. Filling this gap affords important opportunities to extend these studies and to improve our understanding of the differences between the two major clades. Here, we present an EST library from Stylophora pistillata (Esper 1797 and systematically analyze the assembled transcripts compared to putative homologs from the complete proteomes of six well-characterized metazoans: Nematostella vectensis, Hydra magnipapillata, Caenorhabditis elegans, Drosophila melanogaster, Strongylocentrotus purpuratus, Ciona intestinalis and Homo sapiens. Furthermore, comparative analyses of the Stylophora pistillata ESTs were performed against several Cnidaria from the Scleractinia, Actiniaria and Hydrozoa, as well as against other stony corals separately. Functional characterization of S. pistillata transcripts into KOG/COG categories and further description of Wnt and bone morphogenetic protein (BMP signaling pathways showed that the assembled EST library provides sufficient data and coverage. These features of this new library suggest considerable opportunities for extending our understanding of the molecular and physiological behavior of "robust" corals.

  3. Mechanism of Calcite Co-Orientation in the Sea Urchin Tooth

    Energy Technology Data Exchange (ETDEWEB)

    Killian, Christopher; Metzler, Rebecca; Gong, Y. U. T.; Olson, Ian; Aizenberg, Joanna; Politi, Yael; Wilt, Fred; Scholl, Andreas; Young, Anthony; Doran, Andrew; Kunz, Martin; Tamura, Nobumichi; Coppersmith, Susan; Gilbert, P. U. P. A.

    2009-12-01

    Sea urchin teeth are remarkable and complex calcite structures, continuously growing at the forming end and self-sharpening at the mature grinding tip. The calcite (CaCO{sub 3}) crystals of tooth components, plates, fibers, and a high-Mg polycrystalline matrix, have highly co-oriented crystallographic axes. This ability to co-orient calcite in a mineralized structure is shared by all echinoderms. However, the physico-chemical mechanism by which calcite crystals become co-oriented in echinoderms remains enigmatic. Here, we show differences in calcite c-axis orientations in the tooth of the purple sea urchin (Strongylocentrotus purpuratus), using high-resolution X-ray photoelectron emission spectromicroscopy (X-PEEM) and microbeam X-ray diffraction ({mu}XRD). All plates share one crystal orientation, propagated through pillar bridges, while fibers and polycrystalline matrix share another orientation. Furthermore, in the forming end of the tooth, we observe that CaCO{sub 3} is present as amorphous calcium carbonate (ACC). We demonstrate that co-orientation of the nanoparticles in the polycrystalline matrix occurs via solid-state secondary nucleation, propagating out from the previously formed fibers and plates, into the amorphous precursor nanoparticles. Because amorphous precursors were observed in diverse biominerals, solid-state secondary nucleation is likely to be a general mechanism for the co-orientation of biomineral components in organisms from different phyla.

  4. Extraordinary Diversity of Immune Response Proteins among Sea Urchins: Nickel-Isolated Sp185/333 Proteins Show Broad Variations in Size and Charge

    Science.gov (United States)

    Sherman, Lauren S.; Schrankel, Catherine S.; Brown, Kristy J.; Smith, L. Courtney

    2015-01-01

    Effective protection against pathogens requires the host to produce a wide range of immune effector proteins. The Sp185/333 gene family, which is expressed by the California purple sea urchin Strongylocentrotus purpuratus in response to bacterial infection, encodes a highly diverse repertoire of anti-pathogen proteins. A subset of these proteins can be isolated by affinity to metal ions based on multiple histidines, resulting in one to four bands of unique molecular weight on standard Western blots, which vary depending on the individual sea urchin. Two dimensional gel electrophoresis (2DE) of nickel-isolated protein samples followed by Western blot was employed to detect nickel-isolated Sp185/333 (Ni-Sp185/333) proteins and to evaluate protein diversity in animals before and after immune challenge with marine bacteria. Ni-Sp185/333 proteins of the same molecular weight on standard Western blots appear as a broad complex of variants that differ in pI on 2DE Western blots. The Ni-Sp185/333 protein repertoire is variable among animals, and shows a variety of changes among individual sea urchins in response to immune challenges with both the same and different species of bacteria. The extraordinary diversity of the Ni-Sp185/333 proteins may provide significant anti-pathogen capabilities for sea urchins that survive solely on innate immunity. PMID:26406912

  5. Differential Nanos 2 protein stability results in selective germ cell accumulation in the sea urchin.

    Science.gov (United States)

    Oulhen, Nathalie; Wessel, Gary M

    2016-10-01

    Nanos is a translational regulator required for the survival and maintenance of primordial germ cells. In the sea urchin, Strongylocentrotus purpuratus (Sp), Nanos 2 mRNA is broadly transcribed but accumulates specifically in the small micromere (sMic) lineage, in part because of the 3'UTR element GNARLE leads to turnover in somatic cells but retention in the sMics. Here we found that the Nanos 2 protein is also selectively stabilized; it is initially translated throughout the embryo but turned over in the future somatic cells and retained only in the sMics, the future germ line in this animal. This differential stability of Nanos protein is dependent on the open reading frame (ORF), and is independent of the sumoylation and ubiquitylation pathways. Manipulation of the ORF indicates that 68 amino acids in the N terminus of the Nanos protein are essential for its stability in the sMics whereas a 45 amino acid element adjacent to the zinc fingers targets its degradation. Further, this regulation of Nanos protein is cell autonomous, following formation of the germ line. These results are paradigmatic for the unique presence of Nanos in the germ line by a combination of selective RNA retention, distinctive translational control mechanisms (Oulhen et al., 2013), and now also by defined Nanos protein stability. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Dyson shells: a retrospective

    Science.gov (United States)

    Bradbury, Robert J.

    2001-08-01

    More than 40 years have passed since Freeman Dyson suggested that advanced technological civilizations are likely to dismantle planets in their solar systems to harvest all of the energy their stars wastefully radiate into space. Clearly this was an idea that was ahead of its time. Since that time, dozens of SETI searches have been conducted and almost all of them have focused their attention on stars which by definition cannot be the advanced civilizations that Dyson envisioned. I will review the data that created the confusion between Dyson spheres and Dyson shells. The sources that disprove Dyson spheres while still allowing Dyson shells will be discussed. The use of outmoded ideas that have biased the few searches for Dyson Shells that have occurred will be pointed out. An update of the concept of Dyson shells to include our current knowledge of biotechnology, nanotechnology and computer science will be explored. Finally, an approach to setting limits on the abundance of Dyson shells in our galaxy using existing optical astronomical data and future optical satellites will be proposed.

  7. Mussel Shell Impaction in the Esophagus

    Directory of Open Access Journals (Sweden)

    Sunmin Kim

    2013-03-01

    Full Text Available Mussels are commonly used in cooking around the world. The mussel shell breaks more easily than other shells, and the edge of the broken mussel shell is sharp. Impaction can ultimately cause erosion, perforation and fistula. Aside from these complications, the pain can be very intense. Therefore, it is essential to verify and remove the shell as soon as possible. In this report we describe the process of diagnosing and treating mussel shell impaction in the esophagus. Physicians can overlook this unusual foreign body impaction due to lack of experience. When physicians encounter a patient with severe chest pain after a meal with mussels, mussel shell impaction should be considered when diagnosing and treating the patient.

  8. Enzymatic methods for the determination of pollution in seawater using salt resistant alkaline phosphatase from eggs of the sea urchin Strongylocentrotus intermedius

    International Nuclear Information System (INIS)

    Menzorova, Natalie I.; Seitkalieva, Alexandra V.; Rasskazov, Valery A.

    2014-01-01

    Highlights: • Alkaline phosphatase from eggs of the sea urchin (StAP) proved to be active in seawater. • Activity of StAP is inhibited by very low concentrations of heavy metal. • A test to assess sea and fresh water quality has been developed basing on StAP. • For the first time a salt resistant alkaline phosphatase has been found in eukaryote. - Abstract: A new salt resistant alkaline phosphatase from eggs of the sea urchin Strongylocentrotus intermedius (StAP) has been shown to have a unique property to hydrolyze substrate in seawater without loss of enzymatic activity. The enzyme has pH optimum at 8.0–8.5. Model experiments showed various concentrations of copper, zinc, cadmium and lead added to seawater or a standard buffer mixture to inhibit completely the enzyme activity at the concentrations of 15–150 μg/l. StAP sensitivity to the presence in seawater of metals, pesticides, detergents and oil products appears to be considerably less. Samples of seawater taken from aquatic areas of the Troitsy Bay of the Peter the Great Bay, Japan Sea have been shown to inhibit the enzyme activity; the same was shown for the samples of fresh waters. The phosphatase inhibition assay developed proved to be highly sensitive, technically easy-to use allowing to test a great number of samples

  9. Plate shell structures of glass

    DEFF Research Database (Denmark)

    Bagger, Anne

    to their curved shape. A plate shell structure maintains a high stiffness-to-weight ratio, while facilitating the use of plane structural elements. The study focuses on using laminated glass panes for the load bearing facets. Various methods of generating a plate shell geometry are suggested. Together with Ghent......, such as facet size, imperfections, and connection characteristics. The critical load is compared to that of a similar, but smoothly curved, shell structure. Based on the investigations throughout the study, a set of guidelines for the structural design of plate shells of glass is proposed....

  10. Optimised photocatalytic hydrogen production using core–shell AuPd promoters with controlled shell thickness

    DEFF Research Database (Denmark)

    Jones, Wilm; Su, Ren; Wells, Peter

    2014-01-01

    of these materials towards the reforming of alcohols for hydrogen production. The core–shell structured Au–Pd bimetallic nanoparticle supported on TiO2 has being of interest as it exhibited extremely high quantum efficiencies for hydrogen production. However, the effect of shell composition and thickness...... of the nanoparticles by a combination of X-ray absorption fine structure and X-ray photoelectron spectroscopy. Photocatalytic ethanol reforming showed that the core–shell structured Au–Pd promoters supported on TiO2 exhibit enhanced activity compared to that of monometallic Au and Pd as promoters, whilst the core......–shell Au–Pd promoters containing one ML equivalent Pd provide the optimum reactivity....

  11. Nanostructued core–shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada); Cai, Mei [General Motors Research and Development Center, Warren, MI 48090-9055 (United States); Sun, Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada)

    2015-03-30

    Graphical abstract: - Highlights: • Sn nanowires encapsulated in CNTs directly grew on current collectors. • The thickness of CNTs were controlled via growth time, gas flow rate and synthesis temperature. • Thick CNTs contributed to a better capacity retention while thin CNTs led to a higher capacity. • The core–shell structures formed in one-step CVD process. - Abstract: Core–shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C{sub 2}H{sub 4}) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g{sup −1}.

  12. Nanostructued core–shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

    International Nuclear Information System (INIS)

    Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying; Cai, Mei; Sun, Xueliang

    2015-01-01

    Graphical abstract: - Highlights: • Sn nanowires encapsulated in CNTs directly grew on current collectors. • The thickness of CNTs were controlled via growth time, gas flow rate and synthesis temperature. • Thick CNTs contributed to a better capacity retention while thin CNTs led to a higher capacity. • The core–shell structures formed in one-step CVD process. - Abstract: Core–shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C 2 H 4 ) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g −1

  13. Extensions to a nonlinear finite element axisymmetric shell model based on Reissner's shell theory

    International Nuclear Information System (INIS)

    Cook, W.A.

    1981-01-01

    A finite element shell-of-revolution model has been developed to analyze shipping containers under severe impact conditions. To establish the limits for this shell model, I studied the basic assumptions used in its development; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress. (orig./HP)

  14. Core-Shell-Corona Micelles with a Responsive Shell.

    Science.gov (United States)

    Gohy, Jean-François; Willet, Nicolas; Varshney, Sunil; Zhang, Jian-Xin; Jérôme, Robert

    2001-09-03

    A reactor for the synthesis of gold nanoparticles is one of the uses of a poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer (PS-b-P2VP-b-PEO) which forms core-shell-corona micelles in water. Very low polydispersity spherical micelles are observed that consist of a PS core surrounded by a pH-sensitive P2VP shell and a corona of PEO chains end-capped by a hydroxyl group. The corona can act as a site for attaching responsive or sensing molecules. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  15. Biomineral repair of abalone shell apertures.

    Science.gov (United States)

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Porous Core-Shell Nanostructures for Catalytic Applications

    Science.gov (United States)

    Ewers, Trevor David

    Porous core-shell nanostructures have recently received much attention for their enhanced thermal stability. They show great potential in the field of catalysis, as reactant gases can diffuse in and out of the porous shell while the core particle is protected from sintering, a process in which particles coalesce to form larger particles. Sintering is a large problem in industry and is the primary cause of irreversible deactivation. Despite the obvious advantages of high thermal stability, porous core-shell nanoparticles can be developed to have additional interactive properties from the combination of the core and shell together, rather than just the core particle alone. This dissertation focuses on developing new porous core-shell systems in which both the core and shell take part in catalysis. Two types of systems are explored; (1) yolk-shell nanostructures with reducible oxide shells formed using the Kirkendall effect and (2) ceramic-based porous oxide shells formed using sol-gel chemistry. Of the Kirkendall-based systems, Au FexOy and Cu CoO were synthesized and studied for catalytic applications. Additionally, ZnO was explored as a potential shelling material. Sol-gel work focused on optimizing synthetic methods to allow for coating of small gold particles, which remains a challenge today. Mixed metal oxides were explored as a shelling material to make dual catalysts in which the product of a reaction on the core particle becomes a reactant within the shell.

  17. Ge/Si core/shell quantum dots in alumina: tuning the optical absorption by the core and shell size

    Directory of Open Access Journals (Sweden)

    Nekić Nikolina

    2017-03-01

    Full Text Available Ge/Si core/shell quantum dots (QDs recently received extensive attention due to their specific properties induced by the confinement effects of the core and shell structure. They have a type II confinement resulting in spatially separated charge carriers, the electronic structure strongly dependent on the core and shell size. Herein, the experimental realization of Ge/Si core/shell QDs with strongly tunable optical properties is demonstrated. QDs embedded in an amorphous alumina glass matrix are produced by simple magnetron sputtering deposition. In addition, they are regularly arranged within the matrix due to their self-assembled growth regime. QDs with different Ge core and Si shell sizes are made. These core/shell structures have a significantly stronger absorption compared to pure Ge QDs and a highly tunable absorption peak dependent on the size of the core and shell. The optical properties are in agreement with recent theoretical predictions showing the dramatic influence of the shell size on optical gap, resulting in 0.7 eV blue shift for only 0.4 nm decrease at the shell thickness. Therefore, these materials are very promising for light-harvesting applications.

  18. Studies of dust shells around stars

    International Nuclear Information System (INIS)

    Bedijn, P.J.

    1977-01-01

    This thesis deals with some aspects of circumstellar dust shells. This dust shell, emitting infrared radiation, is described by way of its absorptive and emissive properties as well as by the transfer of radiation through the dust shell itself. Model calculations are compared to experimental results and agree reasonably well. The author also discusses the dynamics of the extended shells of gas and dust around newly formed stars

  19. Covarying Shell Growth Parameters and the Regulation of Shell Shape in Marine Bivalves: A Case Study on Tellinoidea

    Directory of Open Access Journals (Sweden)

    Jean Béguinot

    2014-01-01

    Full Text Available Specific parameters characterising shell shape may arguably have a significant role in the adaptation of bivalve molluscs to their particular environments. Yet, such functionally relevant shape parameters (shell outline elongation, dissymmetry, and ventral convexity are not those parameters that the animal may directly control. Rather than shell shape, the animal regulates shell growth. Accordingly, an alternative, growth-based description of shell-shape is best fitted to understand how the animal may control the achieved shell shape. The key point is, in practice, to bring out the link between those two alternative modes of shell-shape descriptions, that is, to derive the set of equations which connects the growth-based shell-shape parameters to the functionally relevant shell-shape parameters. Thus, a preliminary object of this note is to derive this set of equations as a tool for further investigations. A second object of this work is to provide an illustrative example of implementation of this tool. I report on an unexpected negative covariance between growth-based parameters and show how this covariance results in a severe limitation of the range of interspecific variability of the degree of ventral convexity of the shell outline within the superfamily Tellinoidea. Hypotheses are proposed regarding the constraints possibly at the origin of this limitation of interspecific variability.

  20. Pressure Shell Approach to Integrated Environmental Protection

    Science.gov (United States)

    Kennedy, Kriss J.

    2011-01-01

    The next generation of exploration mission human systems will require environmental protection such as radiation protection that is effective and efficient. In order to continue human exploration, habitat systems will require special shells to protect astronauts from hostile environments. The Pressure Shell Approach to integrated environmental (radiation) protection is a multi-layer shell that can be used for multifunctional environmental protection. Self-healing, self-repairing nano technologies and sensors are incorporated into the shell. This shell consists of multiple layers that can be tailored for specific environmental protection needs. Mainly, this innovation focuses on protecting crew from exposure to micrometeorites, thermal, solar flares, and galactic cosmic ray (GCR) radiation. The Pressure Shell Approach consists of a micrometeoroid and secondary ejecta protection layer; a thin, composite shell placed in between two layers that is non-structural; an open cavity layer that can be filled with water, regolith, or polyethylene foam; a thicker composite shell that is a structural load bearing that is placed between two layers; and a bladder coating on the interior composite shell. This multi-layer shell creates an effective radiation protection system. Most of its layers can be designed with the materials necessary for specific environments. In situ materials such as water or regolith can be added to the shell design for supplemental radiation protection.

  1. Engineered inorganic core/shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mélinon, Patrice, E-mail: patrice.melinon@univ-lyon1.fr [Institut Lumière matière Université Claude Bernard Lyon 1 et CNRS et OMNT, Domaine Scientifique de la Doua, Bâtiment Léon Brillouin, 43 Boulevard du 11 Novembre 1918, F 69622 Villeurbanne (France); Begin-Colin, Sylvie [IPCMS et OMNT, 23 rue du Loess BP 43, 67034 STRASBOURG Cedex 2 (France); Duvail, Jean Luc [IMN UMR 6502 et OMNT Campus Sciences : 2 rue de la Houssinire, BP32229, 44322 Nantes Cedex3 (France); Gauffre, Fabienne [SPM et OMNT : Institut des sciences chimiques de Rennes - UMR 6226, 263 Avenue du General Leclerc, CS 74205, 35042 RENNES Cedex (France); Boime, Nathalie Herlin [IRAMIS-NIMBE, Laboratoire Francis Perrin (CEA CNRS URA 2453) et OMNT, Bat 522, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Ledoux, Gilles [Institut Lumière Matière Université Claude Bernard Lyon 1 et CNRS et OMNT, Domaine Scientifique de la Doua, Bâtiment Alfred Kastler 43 Boulevard du 11 Novembre 1918 F 69622 Villeurbanne (France); Plain, Jérôme [Universit de technologie de Troyes LNIO-ICD, CNRS et OMNT 12 rue Marie Curie - CS 42060 - 10004 Troyes cedex (France); Reiss, Peter [CEA Grenoble, INAC-SPrAM, UMR 5819 CEA-CNRS-UJF et OMNT, Grenoble cedex 9 (France); Silly, Fabien [CEA, IRAMIS, SPEC, TITANS, CNRS 2464 et OMNT, F-91191 Gif sur Yvette (France); Warot-Fonrose, Bénédicte [CEMES-CNRS, Université de Toulouse et OMNT, 29 rue Jeanne Marvig F 31055 Toulouse (France)

    2014-10-20

    It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.

  2. Carbon isotopes in mollusk shell carbonates

    Science.gov (United States)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  3. Dynamic centering of liquid shells

    International Nuclear Information System (INIS)

    Tsamopoulos, J.A.; Brown, R.A.

    1987-01-01

    The moderate-amplitude axisymmetric oscillations of an inviscid liquid shell surrounding an incompressible gas bubble are calculated by a multiple-time-scale expansion for initial deformations composed of two-lobed perturbations of the shell and a displacement of the bubble from the center of mass of the liquid. Two types of small-amplitude motion are identified and lead to very different nonlinear dynamic interactions, as described by the results valid up to second order in the amplitude of the initial deformation. In the ''bubble mode,'' the oscillations of the captive bubble and the liquid shell are exactly in phase and the bubble vibrates about its initial eccentric location. The bubble moves toward the center of the drop when the shell is perturbed into a ''sloshing mode'' of oscillation where both interfaces move out of phase. These results explain the centering of liquid shells observed in several experiments

  4. Shells and Patterns

    Science.gov (United States)

    Sutley, Jane

    2009-01-01

    "Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

  5. Four-loop on-shell integrals. MS-on-shell relation and g-2

    Energy Technology Data Exchange (ETDEWEB)

    Marquard, P.

    2013-12-15

    We present first results towards a full four-loop calculation for both the anomalous magnetic moment of the muon and the MS-on-shell relation. The calculation requires the detailed study of an up to now not considered class of diagrams, so-called on-shell diagrams, at four-loop order.

  6. Recent developments in anisotropic heterogeneous shell theory

    CERN Document Server

    Grigorenko, Alexander Ya; Grigorenko, Yaroslav M; Vlaikov, Georgii G

    2016-01-01

    This volume focuses on the relevant general theory and presents some first applications, namely those based on classical shell theory. After a brief introduction, during which the history and state-of-the-art are discussed, the first chapter presents the mechanics of anisotropic heterogeneous shells, covering all relevant assumptions and the basic relations of 3D elasticity, classical and refined shell models. The second chapter examines the numerical techniques that are used, namely discrete orthogonalization, spline-collocation and Fourier series, while the third highlights applications based on classical theory, in particular, the stress-strain state of shallow shells, non-circular shells, shells of revolution, and free vibrations of conical shells. The book concludes with a summary and an outlook bridging the gap to the second volume.

  7. Ni3Si(Al)/a-SiOx core shell nanoparticles: characterization, shell formation, and stability

    Science.gov (United States)

    Pigozzi, G.; Mukherji, D.; Gilles, R.; Barbier, B.; Kostorz, G.

    2006-08-01

    We have used an electrochemical selective phase dissolution method to extract nanoprecipitates of the Ni3Si-type intermetallic phase from two-phase Ni-Si and Ni-Si-Al alloys by dissolving the matrix phase. The extracted nanoparticles are characterized by transmission electron microscopy, energy-dispersive x-ray spectrometry, x-ray powder diffraction, and electron powder diffraction. It is found that the Ni3Si-type nanoparticles have a core-shell structure. The core maintains the size, the shape, and the crystal structure of the precipitates that existed in the bulk alloys, while the shell is an amorphous phase, containing only Si and O (SiOx). The shell forms around the precipitates during the extraction process. After annealing the nanoparticles in nitrogen at 700 °C, the tridymite phase recrystallizes within the shell, which remains partially amorphous. In contrast, on annealing in air at 1000 °C, no changes in the composition or the structure of the nanoparticles occur. It is suggested that the shell forms after dealloying of the matrix phase, where Si atoms, the main constituents of the shell, migrate to the surface of the precipitates.

  8. Fabrication of Foam Shells for ICF Experiments

    Science.gov (United States)

    Czechowicz, D. G.; Acenas, O.; Flowers, J. S.; Nikroo, A.; Paguio, R. R.; Schroen, D. G.; Streit, J.; Takagi, M.

    2004-11-01

    The General Atomics/Schafer team has developed processes to fabricate foam shells targets suitable for ICF experiments. The two most common chemical systems used to produce foam shells have been resorcinol-formaldehyde (R/F) aerogel and divinylbenzene (DVB). Spherical targets have been made in the form of shells and beads having diameters ranging from approximately 0.5 mm to 4.0 mm, and having densities from approximately 100 mg/cc to 250 mg/cc. The work on R/F foam shells has been concentrated on 1) shell fabrication process improvement to obtain high yields ( ˜25%) and 2) depositing a reliable permeation barrier to provide shells for ongoing direct drive experiments at LLE. Development of divinylbenzene foam shells has been mainly directed towards Inertial Fusion Energy applications (at densities as low as 30 mg/cc) and recently for shells for experiments at LLE. Details of the relevant metrology and properties of these foams as well as the range of targets currently available will be discussed.

  9. Radar attenuation in Europa's ice shell: Obstacles and opportunities for constraining the shell thickness and its thermal structure

    Science.gov (United States)

    Kalousová, Klára; Schroeder, Dustin M.; Soderlund, Krista M.

    2017-03-01

    Young surface and possible recent endogenic activity make Europa one of the most exciting solar system bodies and a primary target for spacecraft exploration. Future Europa missions are expected to carry ice-penetrating radar instruments designed to investigate its subsurface thermophysical structure. Several authors have addressed the radar sounders' performance at icy moons, often ignoring the complex structure of a realistic ice shell. Here we explore the variation in two-way radar attenuation for a variety of potential thermal structures of Europa's shell (determined by reference viscosity, activation energy, tidal heating, surface temperature, and shell thickness) as well as for low and high loss temperature-dependent attenuation model. We found that (i) for all investigated ice shell thicknesses (5-30 km), the radar sounder will penetrate between 15% and 100% of the total thickness, (ii) the maximum penetration depth varies laterally, with deepest penetration possible through cold downwellings, (iii) direct ocean detection might be possible for shells of up to 15 km thick if the signal travels through cold downwelling ice or the shell is conductive, (iv) even if the ice/ocean interface is not directly detected, penetration through most of the shell could constrain the deep shell structure through returns from deep non-ocean interfaces or the loss of signal itself, and (v) for all plausible ice shells, the two-way attenuation to the eutectic point is ≲30 dB which shows a robust potential for longitudinal investigation of the ice shell's shallow thermophysical structure.

  10. Vibration of liquid-filled thin shells

    International Nuclear Information System (INIS)

    Kalnins, A.

    1979-01-01

    This paper describes the analysis of free and forced vibration of a thin, axisymmetric shell, which contains some liquid. The axis of symmetry is vertical. Only such vibration is considered which can be produced by a horizontal movement of the base of shell. The objective of this paper is to examine the response of the coupled shell-liquid system for a frequency range lying between zero and the lowest natural sloshing frequency of the liquid. The mass of the liquid is modeled by a stationary and one or more sloshing masses. It is shown how the stationary mass can be incorporated in the vibration analysis of the shell and how to natural frequency of the coupled shell-liquid system can be obtained from a simple formula, if the lowest natural frequency of the shell, plus the stationary mass of the liquid, can be determined. A numerical example is given. (orig.)

  11. On-shell and half-shell effects of the coulomb potential in quantum mechanics

    NARCIS (Netherlands)

    Maag, Jan Willem de

    1984-01-01

    In dit proefschrift wordt de Coulomb potentiaal in de nietrelativistische quantummechanica bestudeerd. Met gebruik van een streng wiskundige beschrijving onderzoeken we, in het bijzonder, on-shell en off-shell eigenschappen. De overeenkomsten en de verschillen met het geval van een glad afgeschermde

  12. Creep buckling of shell structures

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Hagihara, Seiya

    2015-01-01

    The present article contains a review of the literatures on the creep buckling of shell structures published from late 1950's to recent years. In this article, the creep buckling studies on circular cylindrical shells, spherical shells, partial cylindrical shells and other shells are reviewed in addition to creep buckling criteria. Creep buckling is categorized into two types. One is the creep buckling due to quasi-static instability, in which the critical time for creep buckling is determined by tracing a creep deformation versus time curve. The other is the creep buckling due to kinetic instability, in which the critical time can be determined by examining the shape of total potential energy in the vicinity of a quasi-static equilibrium state. Bifurcation buckling and snap-through buckling during creep deformation belong to this type of creep buckling. A few detailed descriptions are given to the bifurcation and snap-through type of creep buckling based on the present authors' works. (author)

  13. Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products.

    Science.gov (United States)

    Cho, Min Guk; Bae, Su Min; Jeong, Jong Youn

    2017-01-01

    This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (-) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed ( p cooking loss in samples with natural calcium powder added was similar ( p >0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher ( p egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities.

  14. 7 CFR 983.29 - Shelled pistachios.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means pistachio...

  15. Vibrations of Thin Piezoelectric Shallow Shells

    Indian Academy of Sciences (India)

    Abstract. In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two-dimensional eigenvalue problem.

  16. Patterning of the turtle shell.

    Science.gov (United States)

    Moustakas-Verho, Jacqueline E; Cebra-Thomas, Judith; Gilbert, Scott F

    2017-08-01

    Interest in the origin and evolution of the turtle shell has resulted in a most unlikely clade becoming an important research group for investigating morphological diversity in developmental biology. Many turtles generate a two-component shell that nearly surrounds the body in a bony exoskeleton. The ectoderm covering the shell produces epidermal scutes that form a phylogenetically stable pattern. In some lineages, the bones of the shell and their ectodermal covering become reduced or lost, and this is generally associated with different ecological habits. The similarity and diversity of turtles allows research into how changes in development create evolutionary novelty, interacting modules, and adaptive physiology and anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Synthesis of Aqueous CdTe/CdS/ZnS Core/shell/shell Quantum Dots by a Chemical Aerosol Flow Method

    Directory of Open Access Journals (Sweden)

    Chen Dong

    2009-01-01

    Full Text Available Abstract This work described a continuous method to synthesize CdTe/CdS/ZnS core/shell/shell quantum dots. In an integrated system by flawlessly combining the chemical aerosol flow system working at high temperature (200–300°C to generate CdTe/CdS intermediate products and an additional heat-up setup at relatively low temperature to overcoat the ZnS shells, the CdTe/CdS/ZnS multishell structures were realized. The as-synthesized CdTe/CdS/ZnS core/shell/shell quantum dots are characterized by photoluminescence spectra, X-ray diffraction (XRD, energy-dispersive X-ray spectra (EDS, transmission electron microscopy (TEM, and high-resolution transmission electron microscopy (HRTEM. Fluorescence and XRD results confirm that the obtained quantum dots have a core/shell/shell structure. It shows the highest quantum yield above 45% when compared to the rhodamine 6G. The core/shell/shell QDs were more stable via the oxidation experiment by H2O2.

  18. Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

    Science.gov (United States)

    Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

    2018-02-01

    Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

  19. Signatures of shell evolution in alpha decay across the N = 126 shell closure

    Science.gov (United States)

    Rui-Wang; Wang, Rui-Yao; Qian, Yi-Bin; Ren, Zhong-Zhou

    2017-06-01

    Within the alpha-cluster model, we particularly investigate the alpha decay of exotic nuclei in the vicinity of the N = 126 neutron shell plus the Z = 82 proton shell. The systematics of alpha-preformation probability (P α ), as an indicator of the shell effect, is deduced from the ratio of the experimental decay width to the calculated one. Through the comparative analysis of the P α trend in the N = 124-130 isotonic chain, the N = 126 and Z = 82 shell closures are believed to strongly affect the formation of the alpha particle before its penetration. Additionally, the P α variety in Po and Rn isotopes is presented as another proof for such an influence. More importantly, it may be concluded that the expected neutron (or proton) shell effect gradually fades away along with the increasing valence proton (or neutron) number. The odd-even staggering presented in the P α value is also discussed. Supported by National Natural Science Foundation of China (11375086, 11535004, 11605089, 11120101005), Natural Science Youth Fund of Jiangsu Province (BK20150762), Fundamental Research Funds for the Central Universities (30916011339), 973 National Major State Basic Research and Development Program of China (2013CB834400), and a Project Funded by the Priority Academic Programme Development of JiangSu Higher Education Institutions (PAPD)

  20. Shell film- and video catalogue 1996

    International Nuclear Information System (INIS)

    1996-01-01

    An overview is given of films and videos that are available through 'Shell Nederland Filmcentrale' (Shell Netherlands Film Center), subdivided into the subjects (1) About Shell; (2) Health, Safety and Environment; (3) Science and Technology; (4) The History of Car(racing); and (5) Historical Overview. 5 ills

  1. 7 CFR 981.6 - Shelled almonds.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds after...

  2. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    KAUST Repository

    Vella, Dominic

    2012-10-01

    Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.

  3. Double containment shell for nuclear power plants

    International Nuclear Information System (INIS)

    Sykora, D.

    1977-01-01

    A double containment shell is proposed for nuclear power plants, especially those equipped with pressurized water reactors. The shell offers increased environmental protection from primary circuit accidents. The inner shell is built of steel or concrete while the outer shell is always built of concrete. The space between the two shells is filled with water and is provided with several manholes and with stiffeners designed for compensation for load due to the water hydrostatic pressure. Water serves the airtight separation of the containment shell inside from the environment and the absorption of heat released in a primary circuit accident. In case the inner shell is made of concrete, it is provided with heat-removal tubes in-built in its walls ensuring rapid heat transfer from the inside of the containment to the water in the interwall space. (Z.M.)

  4. Seismic analysis of axisymmetric shells

    International Nuclear Information System (INIS)

    Jospin, R.J.; Toledo, E.M.; Feijoo, R.A.

    1984-01-01

    Axisymmetric shells subjected to multiple support excitation are studied. The shells are spatialy discretized by the finite element method and in order to obtain estimates for the maximum values of displacements and stresses the response spectrum tecnique is used. Finally, some numerical results are presented and discussed in the case of a shell of revolution with vertical symmetry axis, subjected to seismic ground motions in the horizontal, vertical and rocking directions. (Author) [pt

  5. Creep analysis of orthotropic shells

    International Nuclear Information System (INIS)

    Mehra, V.K.; Ghosh, A.

    1975-01-01

    A method of creep analysis of orthotropic cylindrical shells subjected to axisymmetric loads has been developed. A general study of creep behaviour of cylindrical shells subjected to a uniform internal pressure has been conducted for a wide range of values of anisotropy coefficients and creep law exponent. Analysis includes determination of stress re-distribution, strain rates, stationary state stresses. Application of reference stress technique has been extended to analysis of shells. (author)

  6. Faraday Wave Turbulence on a Spherical Liquid Shell

    Science.gov (United States)

    Holt, R. Glynn; Trinh, Eugene H.

    1996-01-01

    Millimeter-radius liquid shells are acoustically levitated in an ultrasonic field. Capillary waves are observed on the shells. At low energies (minimal acoustic amplitude, thick shell) a resonance is observed between the symmetric and antisymmetric thin film oscillation modes. At high energies (high acoustic pressure, thin shell) the shell becomes fully covered with high-amplitude waves. Temporal spectra of scattered light from the shell in this regime exhibit a power-law decay indicative of turbulence.

  7. Probabilistic risk assessment of the effect of acidified seawater on development stages of sea urchin (Strongylocentrotus droebachiensis).

    Science.gov (United States)

    Chen, Wei-Yu; Lin, Hsing-Chieh

    2018-05-01

    Growing evidence indicates that ocean acidification has a significant impact on calcifying marine organisms. However, there is a lack of exposure risk assessments for aquatic organisms under future environmentally relevant ocean acidification scenarios. The objective of this study was to investigate the probabilistic effects of acidified seawater on the life-stage response dynamics of fertilization, larvae growth, and larvae mortality of the green sea urchin (Strongylocentrotus droebachiensis). We incorporated the regulation of primary body cavity (PBC) pH in response to seawater pH into the assessment by constructing an explicit model to assess effective life-stage response dynamics to seawater or PBC pH levels. The likelihood of exposure to ocean acidification was also evaluated by addressing the uncertainties of the risk characterization. For unsuccessful fertilization, the estimated 50% effect level of seawater acidification (EC50 SW ) was 0.55 ± 0.014 (mean ± SE) pH units. This life stage was more sensitive than growth inhibition and mortality, for which the EC50 values were 1.13 and 1.03 pH units, respectively. The estimated 50% effect levels of PBC pH (EC50 PBC ) were 0.99 ± 0.05 and 0.88 ± 0.006 pH units for growth inhibition and mortality, respectively. We also predicted the probability distributions for seawater and PBC pH levels in 2100. The level of unsuccessful fertilization had 50 and 90% probability risks of 5.07-24.51 (95% CI) and 0-6.95%, respectively. We conclude that this probabilistic risk analysis model is parsimonious enough to quantify the multiple vulnerabilities of the green sea urchin while addressing the systemic effects of ocean acidification. This study found a high potential risk of acidification affecting the fertilization of the green sea urchin, whereas there was no evidence for adverse effects on growth and mortality resulting from exposure to the predicted acidified environment.

  8. Study of characterization of trace elements in marine shells of Sambaqui: correlation between recent and old shells

    International Nuclear Information System (INIS)

    Gomez, Mauro Roger Batista Pousada; Rocha, Flavio Roberto; Silva, Paulo Sergio Cardoso da

    2013-01-01

    Calcium carbonate of recent and ancient C. rhizophorae oyster shells was analyzed for the determination of trace elements by instrumental neutron activation analysis. The ancient shells belong to a Sambaqui located in Cananeia region, South of Sao Paulo state and the recent ones are from an oyster production farm in the same region Studies related to the element concentrations in molluscs shell has been done as a tentative of establishing the element concentrations with palio-environmental factor. In this study it was aimed to verify differences in the elemental constitution of recent and ancient oyster shells that present potential for being used as indicator of marine changes. Results indicated that the elements Br, Ce, La, Na, Sm and An are higher in recent shells and the elements Cr, Fe Sc and Th are higher in ancient shells. Statistical analyses performed indicated that the enrichment of the light rare earth elements related to Ca are possibly good candidates for these palio-environmental studies. (author)

  9. Foam shell project: Progress report

    International Nuclear Information System (INIS)

    Overturf, G.; Reibold, B.; Cook, B.; Schroen-Carey, D.

    1994-01-01

    The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 μm thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D 2 or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE

  10. Thin-shell wormholes in dilaton gravity

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2005-01-01

    In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed

  11. The dorsal shell wall structure of Mesozoic ammonoids

    Directory of Open Access Journals (Sweden)

    Gregor Radtke

    2017-03-01

    Full Text Available The study of pristine preserved shells of Mesozoic Ammonoidea shows different types of construction and formation of the dorsal shell wall. We observe three major types: (i The vast majority of Ammonoidea, usually planispirally coiled, has a prismatic reduced dorsal shell wall which consists of an outer organic component (e.g., wrinkle layer, which is the first layer to be formed, and the subsequently formed dorsal inner prismatic layer. The dorsal mantle tissue suppresses the formation of the outer prismatic layer and nacreous layer. With the exception of the outer organic component, secretion of a shell wall is omitted at the aperture. A prismatic reduced dorsal shell wall is always secreted immediately after the hatching during early teleoconch formation. Due to its broad distribution in (planispiral Ammonoidea, the prismatic reduced dorsal shell wall is probably the general state. (ii Some planispirally coiled Ammonoidea have a nacreous reduced dorsal shell wall which consists of three mineralized layers: two prismatic layers (primary and secondary dorsal inner prismatic layer and an enclosed nacreous layer (secondary dorsal nacreous layer. The dorsal shell wall is omitted at the aperture and was secreted in the rear living chamber. Its layers are a continuation of an umbilical shell doubling (reinforcement by additional shell layers that extends towards the ventral crest of the preceding whorl. The nacreous reduced dorsal shell wall is formed in the process of ontogeny following a prismatic reduced dorsal shell wall. (iii Heteromorph and some planispirally coiled taxa secrete a complete dorsal shell wall which forms a continuation of the ventral and lateral shell layers. It is formed during ontogeny following a prismatic reduced dorsal shell wall or a priori. The construction is identical with the ventral and lateral shell wall, including a dorsal nacreous layer. The wide distribution of the ability to form dorsal nacre indicates that it is

  12. Preparation of yolk-shell MoS2 nanospheres covered with carbon shell for excellent lithium-ion battery anodes

    Science.gov (United States)

    Guo, Bangjun; Feng, Yu; Chen, Xiaofan; Li, Bo; Yu, Ke

    2018-03-01

    Molybdenum disulfide is regarded as one of the most promising electrode materials for high performance lithium-ion batteries. Designing firm basal structure is a key point to fully utilize the high capacity of layered MoS2 nanomaterials. Here, yolk-shell structured MoS2 nanospheres is firstly designed and fabricated to meet this needs. This unique yolk-shell nanospheres are transformed from solid nanospheres by a simply weak alkaline etching method. Then, the yolk-shell MoS2/C is synthesized by a facile process to protect the outside MoS2 shell and promote the conductivity. Taking advantages of high capacity and well-defined cavity space, allowing the core MoS2 to expand freely without breaking the outer shells, yolk-shell MoS2/C nanospheres delivers long cycle life (94% of capacity retained after 200 cycles) and high rate behaviour (830 mA h g-1 at 5 A g-1). This design of yolk-shell structure may set up a new strategy for preparing next generation anode materials for LIBs.

  13. Au@Ag core-shell nanocubes with finely tuned and well-controlled sizes, shell thicknesses, and optical properties.

    Science.gov (United States)

    Ma, Yanyun; Li, Weiyang; Cho, Eun Chul; Li, Zhiyuan; Yu, Taekyung; Zeng, Jie; Xie, Zhaoxiong; Xia, Younan

    2010-11-23

    This paper describes a facile method for generating Au@Ag core-shell nanocubes with edge lengths controllable in the range of 13.4-50 nm. The synthesis involved the use of single-crystal, spherical Au nanocrystals of 11 nm in size as the seeds in an aqueous system, with ascorbic acid serving as the reductant and cetyltrimethylammonium chloride (CTAC) as the capping agent. The thickness of the Ag shells could be finely tuned from 1.2 to 20 nm by varying the ratio of AgNO(3) precursor to Au seeds. We also investigated the growth mechanism by examining the effects of seeds (capped by CTAC or cetyltrimethylammonium bromide(CTAB)) and capping agent (CTAC vs CTAB) on both size and shape of the resultant core-shell nanocrystals. Our results clearly indicate that CTAC worked much better than CTAB as a capping agent in both the syntheses of Au seeds and Au@Ag core-shell nanocubes. We further studied the localized surface plasmon resonance properties of the Au@Ag nanocubes as a function of the Ag shell thickness. By comparing with the extinction spectra obtained from theoretical calculations, we derived a critical value of ca. 3 nm for the shell thickness at which the plasmon excitation of the Au cores would be completely screened by the Ag shells. Moreover, these Au@Ag core-shell nanocubes could be converted into Au-based hollow nanostructures containing the original Au seeds in the interiors through a galvanic replacement reaction.

  14. Ni(3)Si(Al)/a-SiO(x) core-shell nanoparticles: characterization, shell formation, and stability.

    Science.gov (United States)

    Pigozzi, G; Mukherji, D; Gilles, R; Barbier, B; Kostorz, G

    2006-08-28

    We have used an electrochemical selective phase dissolution method to extract nanoprecipitates of the Ni(3)Si-type intermetallic phase from two-phase Ni-Si and Ni-Si-Al alloys by dissolving the matrix phase. The extracted nanoparticles are characterized by transmission electron microscopy, energy-dispersive x-ray spectrometry, x-ray powder diffraction, and electron powder diffraction. It is found that the Ni(3)Si-type nanoparticles have a core-shell structure. The core maintains the size, the shape, and the crystal structure of the precipitates that existed in the bulk alloys, while the shell is an amorphous phase, containing only Si and O (SiO(x)). The shell forms around the precipitates during the extraction process. After annealing the nanoparticles in nitrogen at 700 °C, the tridymite phase recrystallizes within the shell, which remains partially amorphous. In contrast, on annealing in air at 1000 °C, no changes in the composition or the structure of the nanoparticles occur. It is suggested that the shell forms after dealloying of the matrix phase, where Si atoms, the main constituents of the shell, migrate to the surface of the precipitates.

  15. Radar attenuation in Europa's ice shell: obstacles and opportunities for constraining shell thickness and thermal structure

    Science.gov (United States)

    Kalousova, Klara; Schroeder, Dustin M.; Soderlund, Krista M.; Sotin, Christophe

    2016-10-01

    With its strikingly young surface and possibly recent endogenic activity, Europa is one of the most exciting bodies within our Solar System and a primary target for spacecraft exploration. Future missions to Europa are expected to carry ice penetrating radar instruments which are powerful tools to investigate the subsurface thermophysical structure of its ice shell.Several authors have addressed the 'penetration depth' of radar sounders at icy moons, however, the concept and calculation of a single value penetration depth is a potentially misleading simplification since it ignores the thermal and attenuation structure complexity of a realistic ice shell. Here we move beyond the concept of a single penetration depth by exploring the variation in two-way radar attenuation for a variety of potential thermal structures of Europa's ice shell as well as for a low loss and high loss temperature-dependent attenuation model. The possibility to detect brines is also investigated.Our results indicate that: (i) for all ice shell thicknesses investigated (5-30 km), a nominal satellite-borne radar sounder will penetrate between 15% and 100% of the total thickness, (ii) the maximum penetration depth strongly varies laterally with the deepest penetration possible through the cold downwellings, (iii) the direct detection of the ice/ocean interface might be possible for shells of up to 15 km if the radar signal travels through the cold downwelling, (iv) even if the ice/ocean interface is not detected, the penetration through most of the shell could constrain the deep shell structure through the loss of signal, and (v) for all plausible ice shells the two-way attenuation to the eutectic point is ≤30 dB which shows a robust potential for longitudinal investigation of the ice shell's shallow structure.Part of this work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. K.K. acknowledges support by the Grant Agency of the

  16. Stationary spherical shells around Kerr-Newman naked singularities

    International Nuclear Information System (INIS)

    Zdenek Stuchlik; Stanislav Hledik

    1998-01-01

    It is shown that in the field of some Kerr-Newman naked singularities a stationary spherical shell of charged dust can exist, with the specific charge being the same for all particles of the dusty shell. Gravitational attractions acting on the particles are balanced by electromagnetic repulsion in such a way that the shell is stable against radial perturbations. Particles of the shell move along orbits with constant latitude and radius. Rotation of the shell is differential. The shell is corotating relative to static observers at infinity, but it is counter rotating relative to the family of locally non-rotating observers. No such a shell can exist in the field of Kerr-Newman black holes. (authors)

  17. Modeling plate shell structures using pyFormex

    DEFF Research Database (Denmark)

    Bagger, Anne; Verhegghe, Benedict; Hertz, Kristian Dahl

    2009-01-01

    A shell structure made of glass combines a light-weight structural concept with glass’ high permeability to light. If the geometry of the structure is plane-based facetted (plate shell structure), the glass elements will be plane panes, and these glass panes will comprise the primary load...... (plate shells and triangulated lattice shells) may not differ in complexity regarding the topology, but when it comes to the practical generation of the geometry, e.g. in CAD, the plate shell is far more troublesome to handle than the triangulated geometry. The free software tool “pyFormex”, developed...

  18. Core–shell interaction and its impact on the optical absorption of pure and doped core-shell CdSe/ZnSe nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinqin; Cui, Yingqi; Zeng, Qun; Yang, Mingli, E-mail: myang@scu.edu.cn [Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065 (China); Yu, Shengping [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China)

    2016-04-07

    The structural, electronic, and optical properties of core-shell nanoclusters, (CdSe){sub x}@(CdSe){sub y} and their Zn-substituted complexes of x = 2–4 and y = 16–28, were studied with density functional theory calculations. The substitution was applied in the cores, the shells, and/or the whole clusters. All these clusters are characterized by their core-shell structures in which the core-shell interaction was found different from those in core or in shell, as reflected by their bondlengths, volumes, and binding energies. Moreover, the core and shell combine together to compose a new cluster with electronic and optical properties different from those of separated individuals, as reflected by their HOMO-LUMO gaps and optical absorptions. With the substitution of Cd by Zn, the structural, electronic, and optical properties of clusters change regularly. The binding energy increases with Zn content, attributed to the strong Zn–Se bonding. For the same core/shell, the structure with a CdSe shell/core has a narrower gap than that with a ZnSe shell/core. The optical absorption spectra also change accordingly with Zn substitution. The peaks blueshift with increasing Zn concentration, accompanying with shape variations in case large number of Cd atoms are substituted. Our calculations reveal the core-shell interaction and its influence on the electronic and optical properties of the core-shell clusters, suggesting a composition–structure–property relationship for the design of core-shell CdSe and ZnSe nanoclusters.

  19. Some Differential Geometric Relations in the Elastic Shell

    Directory of Open Access Journals (Sweden)

    Xiaoqin Shen

    2016-01-01

    Full Text Available The theory of the elastic shells is one of the most important parts of the theory of solid mechanics. The elastic shell can be described with its middle surface; that is, the three-dimensional elastic shell with equal thickness comprises a series of overlying surfaces like middle surface. In this paper, the differential geometric relations between elastic shell and its middle surface are provided under the curvilinear coordinate systems, which are very important for forming two-dimensional linear and nonlinear elastic shell models. Concretely, the metric tensors, the determinant of metric matrix field, the Christoffel symbols, and Riemann tensors on the three-dimensional elasticity are expressed by those on the two-dimensional middle surface, which are featured by the asymptotic expressions with respect to the variable in the direction of thickness of the shell. Thus, the novelty of this work is that we can further split three-dimensional mechanics equations into two-dimensional variation problems. Finally, two kinds of special shells, hemispherical shell and semicylindrical shell, are provided as the examples.

  20. Determination of shell energies. Nuclear deformations and fission barriers

    International Nuclear Information System (INIS)

    Koura, Hiroyuki; Tachibana, Takahiro; Uno, Masahiro; Yamada, Masami.

    1996-01-01

    We have been studying a method of determining nuclear shell energies and incorporating them into a mass formula. The main feature of this method lies in estimating shell energies of deformed nuclei from spherical shell energies. We adopt three assumptions, from which the shell energy of a deformed nucleus is deduced to be a weighted sum of spherical shell energies of its neighboring nuclei. This shell energy should be called intrinsic shell energy since the average deformation energy also acts as an effective shell energy. The ground-state shell energy of a deformed nucleus and its equilibrium shape can be obtained by minimizing the sum of these two energies with respect to variation of deformation parameters. In addition, we investigate the existence of fission isomers for heavy nuclei with use of the obtained shell energies. (author)

  1. Lessons Not Learned. The Other Shell Report 2004

    International Nuclear Information System (INIS)

    Harden, M.; Walker, N.; Griffiths, H.; Verweij, M.

    2005-06-01

    The third alternative Shell Corporate Social Responsibility (CSR) report is presented on behalf of several of the many communities that live on Shell's 'fencelines', next to Shell's refineries, depots and pipelines. This 2004 report builds on reports of the past two years 'Failing the Challenge', (2002) and 'Behind the Shine' (2003) which chronicled Shell's impacts around the world. It gives critical updates of Shell's performance over the past year

  2. Strength Calculation of Locally Loaded Orthotropic Shells

    Directory of Open Access Journals (Sweden)

    Yu. I. Vinogradov

    2015-01-01

    Full Text Available The article studies laminated orthotropic cylindrical, conic, spherical, and toroidal shells, which are often locally loaded in the aircraft designs over small areas of their surfaces.The aim of this work is to determine stress concentration in shells versus structure of orthotropic composite material, shell form and parameters, forms of loading areas, which borders do not coincide with lines of main curvatures of shells. For this purpose, an analytical computing algorithm to estimate strength of shells in terms of stress is developed. It enables us to have solution results of the boundary value problem with a controlled error. To solve differential equations an analytical method is used. An algorithm of the boundary value problem solution is multiplicative.The main results of researches are graphs of stress concentration in the orthotropic shells versus their parameters and areas of loading lineated by circles and ellipses.Among the other works aimed at determination of stress concentration in shells, the place of this one is defined by the analytical solution of applied problems for strength estimation in terms of shell stresses of classical forms.The developed effective analytical algorithm to solve the boundary value problem and received results are useful in research and development.

  3. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    NARCIS (Netherlands)

    Schilthuizen, M.

    2003-01-01

    Background: Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not

  4. Shell coal gasification process

    Energy Technology Data Exchange (ETDEWEB)

    Hennekes, B. [Shell Global Solutions (US) Inc. (United States). Technology Marketing

    2002-07-01

    The presentation, on which 17 slides/overheads are included in the papers, explained the principles of the Shell coal gasification process and the methods incorporated for control of sulfur dioxide, nitrogen oxides, particulates and mercury. The economics of the process were discussed. The differences between gasification and burning, and the differences between the Shell process and other processes were discussed.

  5. Cylindrical thin-shell wormholes

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2004-01-01

    A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity

  6. Standardized CSR and climate performance: why is Shell willing, but Hydro reluctant?; Shell; Hydro

    Energy Technology Data Exchange (ETDEWEB)

    Boasson, Elin Lerum; Wettestad, Joergen

    2007-06-15

    This report aims to contribute to the ongoing discussion concerning whether CSR merely serves to streamline company rhetoric or also has an influence on actual efforts. We discuss the tangible effects of CSR instruments on the climate-related rules and performances of the two different oil companies Hydro and Shell. First we explore whether similar CSR instruments lead to similar climate-related rules and practices in the two companies. Both Hydro and Shell adhere to the Global Compact (GC), the Global Reporting Initiative (GRI), the Carbon Disclosure Project (CDP) and the Global Gas Flaring Reduction Public-Private Partnership (GGFR). The report concludes that the GC has not rendered any tangible effects in either of the companies. Concerning the other instruments, Hydro has only followed the instrument requirements that fit their initial approach, and refrained from all deviating requirements. Shell has been more malleable, but we have noted few effects on the actual emissions and business portfolio resulting from the instrument adherence. Second, we assess how the differing results of the similar CSR portfolio may be explained. The reluctant attitude of the leaders in Hydro and the strong CSR motivation of Shell's executives result in significant differences. Hydro executives are able to constrain the effects of the instrument adherence. With Shell we note the opposite pattern: Its leaders promoted the instruments to be translated into internal rules, but a general lack of hierarchical structures hinders them from governing the conduct of various sub-organisations. The very diversity of the Shell culture helps to explain why the efforts of its executives have resulted in limited impact. The strength of the Hydro culture makes the corporation resistant to the instruments. Moreover, Hydro is strikingly shielded by virtue of its strong position in Norway. In contrast, Shell is more strongly affected by the global field of petroleum and the global field of CSR

  7. The influence of MOVPE growth conditions on the shell of core-shell GaN microrod structures

    Science.gov (United States)

    Schimpke, Tilman; Avramescu, Adrian; Koller, Andreas; Fernando-Saavedra, Amalia; Hartmann, Jana; Ledig, Johannes; Waag, Andreas; Strassburg, Martin; Lugauer, Hans-Jürgen

    2017-05-01

    A core-shell geometry is employed for most next-generation, three-dimensional opto-electric devices based on III-V semiconductors and grown by metal organic vapor phase epitaxy (MOVPE). Controlling the shape of the shell layers is fundamental for device optimization, however no detailed analysis of the influence of growth conditions has been published to date. We study homogeneous arrays of gallium nitride core-shell microrods with height and diameter in the micrometer range and grown in a two-step selective area MOVPE process. Changes in shell shape and homogeneity effected by deliberately altered shell growth conditions were accurately assessed by digital analysis of high-resolution scanning electron microscope images. Most notably, two temperature regimes could be established, which show a significantly different behavior with regard to material distribution. Above 900 °C of wafer carrier temperature, the shell thickness along the growth axis of the rods was very homogeneous, however variations between vicinal rods increase. In contrast, below 830 °C the shell thickness is higher close to the microrod tip than at the base of the rods, while the lateral homogeneity between neighboring microrods is very uniform. This temperature effect could be either amplified or attenuated by changing the remaining growth parameters such as reactor pressure, structure distance, gallium precursor, carrier gas composition and dopant materials. Possible reasons for these findings are discussed with respect to GaN decomposition as well as the surface and gas phase diffusion of growth species, leading to an improved control of the functional layers in next-generation 3D V-III devices.

  8. Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells

    Directory of Open Access Journals (Sweden)

    Laurie Dolan

    Full Text Available Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control, 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week no observable adverse effect level (NOAEL of 150 000 ppm in rats and is not genotoxic at the doses analyzed. Keywords: Pecan shell, Fiber, Rat, Diet, Toxicity, Mutagenicity

  9. Electron spin resonance dating of shells from the sambaqui (shell mound) Capelinha, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Kinoshita, A.; Figuty, L.; Baffa, O.

    2006-01-01

    Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valley in the State of Sao Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archaeological doses obtained were (8.05±0.07) Gy and (9.50±0.03) Gy. Since the last site was previously dated by C-14 (Beta -Analytics, Beta 153988) giving: 8860 +/- 60 years BP (conventional age) and 10180 to 9710 years BP (calibrated age), the archaeological dose found for this shell was used to determine the local rate of (0.93 to 0.98) mGy/year, that aggress with other surveys done in the region. Using this dose rate the age of the second shell was found to be 8.14 to 8.73 ky BP that agrees with the stratigraphy of the site. (author)

  10. Soft template synthesis of yolk/silica shell particles.

    Science.gov (United States)

    Wu, Xue-Jun; Xu, Dongsheng

    2010-04-06

    Yolk/shell particles possess a unique structure that is composed of hollow shells that encapsulate other particles but with an interstitial space between them. These structures are different from core/shell particles in that the core particles are freely movable in the shell. Yolk/shell particles combine the properties of each component, and can find potential applications in catalysis, lithium ion batteries, and biosensors. In this Research News article, a soft-template-assisted method for the preparation of yolk/silica shell particles is presented. The demonstrated method is simple and general, and can produce hollow silica spheres incorporated with different particles independent of their diameters, geometry, and composition. Furthermore, yolk/mesoporous silica shell particles and multishelled particles are also prepared through optimization of the experimental conditions. Finally, potential applications of these particles are discussed.

  11. WHAT IS THE SHELL AROUND R CORONAE BOREALIS?

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, Edward J.; Clayton, Geoffrey C.; Marcello, Dominic C. [Dept. of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Lockman, Felix J., E-mail: emonti2@lsu.edu, E-mail: gclayton@fenway.phys.lsu.edu, E-mail: dmarce1@tigers.lsu.edu, E-mail: jlockman@nrao.edu [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States)

    2015-07-15

    The hydrogen-deficient, carbon-rich R Coronae Borealis (RCB) stars are known for being prolific producers of dust which causes their large iconic declines in brightness. Several RCB stars, including R Coronae Borealis (R CrB), itself, have large extended dust shells seen in the far-infrared. The origin of these shells is uncertain but they may give us clues to the evolution of the RCB stars. The shells could form in three possible ways. (1) They are fossil Planetary Nebula (PN) shells, which would exist if RCB stars are the result of a final, helium-shell flash, (2) they are material left over from a white-dwarf (WD) merger event which formed the RCB stars, or (3) they are material lost from the star during the RCB phase. Arecibo 21 cm observations establish an upper limit on the column density of H I in the R CrB shell implying a maximum shell mass of ≲0.3 M{sub ☉}. A low-mass fossil PN shell is still a possible source of the shell although it may not contain enough dust. The mass of gas lost during a WD merger event will not condense enough dust to produce the observed shell, assuming a reasonable gas-to-dust ratio. The third scenario where the shell around R CrB has been produced during the star’s RCB phase seems most likely to produce the observed mass of dust and the observed size of the shell. But this means that R CrB has been in its RCB phase for ∼10{sup 4} years.

  12. Studies on Freezing of Shell-Fish-I

    Science.gov (United States)

    Song, Dae Jin; Konagaya, Shiro; Tanaka, Takeo

    Ark shell, Anadara broughtonii(Shrenk), are commonly eaten raw or under-done in Korea, Japan, and East Asian countries. Along with a recent remarkable development of culture fisheries, Ark shell has become one of the commercially important shell-fish species. Transportation and storage of large quantities of shell-fish is becoming increasingly important. This work was begun with this background to make clear the effects of temperature and length of storage time on the quality of frozen stored ark shell. Results are as follows : (1) There was little chang in amounts of free and expressible drip from ark shell flesh frozen stored at -40°CdegC for 6 months. Water holding capacity of the same meat was almost constant over 6 months storage. However, a mounts of both drip increased markedly after 2 months storage at -10°C. (2) Protein extractibility of ark shell flesh tended to decrease gradually from the begining when stored at -10°C, while at -20°C, the protein extractibility was stable for 3 months before decreasing gradually. However at -40°C, the protein extractibility was stable for 6 months. It was found that paramyosin was very stable even when the ark shell was frozen stored at -10°C. (3) It was observed that ark shell flesh became tough when frozen. The toughness of ark shell flesh as measured by an instrument increased with frozen storage time and increased temperature. (4) In the smooth muscle, it was histologically observed that initial small ice crystals formed between muscle bundles grew larger during frozen storage. It was found that the higher the storage temperature, the bigger the ice crystals formed. Aggregation of some muscle fiber and empty spaces between muscle bundles were observd after thawed muscles frozen stored at relatively high temperature such as -10°C.

  13. Atomistic tight-binding computations of the structural and optical properties of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals

    Science.gov (United States)

    Sukkabot, Worasak

    2018-05-01

    A study of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals is carried out using atomistic tight-binding theory and the configuration interaction method to provide information for applications in bioimaging, biolabeling, display devices and near-infrared electronic instruments. The calculations yield the dependences of the internal and external passivated shells on the natural behaviours of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals. The reduction of the optical band gaps is observed with increasing numbers of monolayers in the external ZnS shell due to quantum confinement. Interestingly, the optical band gaps of CdTe/CdS/ZnS core/shell/shell nanocrystals are greater than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. In the presence of an external ZnS-coated shell, electron-hole wave function overlaps, oscillation strengths, ground-state exchange energies and Stokes shift are improved, whereas ground-state coulomb energies and fine-structure splitting are reduced. The oscillation strengths, Stokes shift and fine-structure splitting are reduced with the increase in external ZnS shell thickness. The oscillation strengths, Stokes shift and fine-structure splitting of CdTe/CdS/ZnS core/shell/shell nanocrystals are larger than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. Reduction of the atomistic electron-hole interactions is observed with increasing external ZnS shell size. The strong electron-hole interactions are more probed in CdTe/CdS/ZnS core/shell/shell nanocrystals than in CdTe/CdSe/ZnS core/shell/shell nanocrystals.

  14. Development of Mortar Simulator with Shell-In-Shell System – Problem of External Ballistics

    Directory of Open Access Journals (Sweden)

    A. Fedaravicius

    2007-01-01

    Full Text Available The shell-in-shell system used in the mortar simulator raises a number of non-standard technical and computational problems starting from the requirement to distribute the propelling blast energy between the warhead and the ballistic barrel, finishing with the requirement that the length of warhead's flight path must be scaled to combat shell firing tables. The design problem of the simulator is split into two parts – the problem of external ballistics where the initial velocities of the warhead must be determined, and the problem of internal ballistics – where the design of the cartridge and the ballistic barrel must be performed.

  15. Three-dimensional flat shell-to-shell coupling: numerical challenges

    Science.gov (United States)

    Guo, Kuo; Haikal, Ghadir

    2017-11-01

    The node-to-surface formulation is widely used in contact simulations with finite elements because it is relatively easy to implement using different types of element discretizations. This approach, however, has a number of well-known drawbacks, including locking due to over-constraint when this formulation is used as a twopass method. Most studies on the node-to-surface contact formulation, however, have been conducted using solid elements and little has been done to investigate the effectiveness of this approach for beam or shell elements. In this paper we show that locking can also be observed with the node-to-surface contact formulation when applied to plate and flat shell elements even with a singlepass implementation with distinct master/slave designations, which is the standard solution to locking with solid elements. In our study, we use the quadrilateral four node flat shell element for thin (Kirchhoff-Love) plate and thick (Reissner-Mindlin) plate theory, both in their standard forms and with improved formulations such as the linked interpolation [1] and the Discrete Kirchhoff [2] elements for thick and thin plates, respectively. The Lagrange multiplier method is used to enforce the node-to-surface constraints for all elements. The results show clear locking when compared to those obtained using a conforming mesh configuration.

  16. Three-dimensional flat shell-to-shell coupling: numerical challenges

    Directory of Open Access Journals (Sweden)

    Guo Kuo

    2017-11-01

    Full Text Available The node-to-surface formulation is widely used in contact simulations with finite elements because it is relatively easy to implement using different types of element discretizations. This approach, however, has a number of well-known drawbacks, including locking due to over-constraint when this formulation is used as a twopass method. Most studies on the node-to-surface contact formulation, however, have been conducted using solid elements and little has been done to investigate the effectiveness of this approach for beam or shell elements. In this paper we show that locking can also be observed with the node-to-surface contact formulation when applied to plate and flat shell elements even with a singlepass implementation with distinct master/slave designations, which is the standard solution to locking with solid elements. In our study, we use the quadrilateral four node flat shell element for thin (Kirchhoff-Love plate and thick (Reissner-Mindlin plate theory, both in their standard forms and with improved formulations such as the linked interpolation [1] and the Discrete Kirchhoff [2] elements for thick and thin plates, respectively. The Lagrange multiplier method is used to enforce the node-to-surface constraints for all elements. The results show clear locking when compared to those obtained using a conforming mesh configuration.

  17. Structural shell analysis understanding and application

    CERN Document Server

    Blaauwendraad, Johan

    2014-01-01

    The mathematical description of the properties of a shell is much more elaborate than those of beam and plate structures. Therefore many engineers and architects are unacquainted with aspects of shell behaviour and design, and are not familiar with sufficiently reliable shell theories for the different shell types as derived in the middle of the 20th century. Rather than contributing to theory development, this university textbook focuses on architectural and civil engineering schools. Of course, practising professionals will profit from it as well. The book deals with thin elastic shells, in particular with cylindrical, conical and spherical types, and with elliptic and hyperbolic paraboloids. The focus is on roofs, chimneys, pressure vessels and storage tanks. Special attention is paid to edge bending disturbance zones, which is indispensable knowledge in FE meshing. A substantial part of the book results from research efforts in the mid 20th century at Delft University of Technology. As such, it is a valua...

  18. Thermoluminescence analysis of irradiated oyster shells

    International Nuclear Information System (INIS)

    Cruz-Zaragoza, E.; Marcazzó, J.; Della Monaca, S.; Boniglia, C.; Gargiulo, R.; Bortolin, E.

    2012-01-01

    This paper reports the thermoluminescence (TL) analysis performed on the oyster shells powder. TL response of 60 Co gamma-rays irradiated samples were studied in the range from 80 Gy to 8 kGy doses. TL signal of irradiated shell powder was higher as compared to the unirradiated control samples, which allowed to identify the irradiated oysters. Results show that the oyster shells have good TL properties and can be useful for the identification of irradiated seafood as well as for the evaluation of the treatment dose. - Highlights: ► TL properties of irradiated oyster shell powder were studied. ► The SEM analysis shows that several elements are present in oyster shell powder. ► Calcite is the main component in the samples and β-calcite is also present. ► Following the European Standard EN 1788, the irradiated oyster can be identified. ► Determination of absorbed dose is possible by performing a preheat treatment.

  19. An empirical model of Onecut binding activity at the sea urchin SM50 C-element gene regulatory region.

    Science.gov (United States)

    Otim, Ochan

    2017-01-01

    Studying the formation of endoskeleton in many species is complex and difficult. The sea urchin embryo offers an unparalleled platform for understanding this process because of the ease with which its skeletogenic mesenchyme cells can be manipulated. In this study, preliminary evidence from biochemical studies towards understanding the role of the Onecut transcription factor during sea urchin skeletogenic mesenchyme cell specification is presented. Based on the evidence, an empirical model is proposed showing how Onecut, together with associated co-factors, may be using the C-element of the SM50 gene regulatory region in advance of the sea urchin Strongylocentrotus purpuratus spicule development. In the model, Onecut recognizes and binds the DNA sequence CATCGATCTC in the C-element without temporal restriction. Onecut then utilizes different sets of co-factors to switch from its unknown function early in development (four cell stage to the mesenchyme blastula stage), to its known role in the oral-aboral boundary thereafter. At the writing of this report, definitive evidence as to whether the "early" factors are expressed in all cells except the micromere lineages, or whether the "late" factors are expressed in micromere descendants or ectodermal precursors only are lacking. The former would suggest a possible Onecut repression function for the early co-factors outside the micromere lineages; the latter scenario would suggest a Onecut activation function for the late co-factors in the presumptive ciliary band.

  20. Developmental expression of a cell surface protein involved in sea urchin skeleton formation

    International Nuclear Information System (INIS)

    Farach, M.C.; Valdizan, M.; Park, H.R.; Decker, G.L.; Lennarz, W.J.

    1986-01-01

    The authors have previously used a monoclonal antibody (1223) to identify a 130 Kd cell surface protein involved in skeleton formation is sea urchin embryos. In the current study the authors have examined the expression of the 1223 antigen over the course of development of embryos of two species, Strongylocentrotus purpuratus and Lytechinus pictus. The 130 Kd protein is detected in S. purp eggs on immunoblots. Labeling with [ 3 H] leucine and immunoaffinity chromatography show that it also is synthesized shortly after fertilization. Immunofluroescence reveals that at this early stage the 1223 antigen is uniformly distributed on all of the cells. Synthesis decreases to a minimum by the time of hatching (18 h), as does the total amount of antigen present in the embryo. A second period of synthesis commences at the mesenchyme blastula stage, when the spicule-forming primary mesenchyme cells (PMCs) have appeared. During this later stage, synthesis and cell surface expression are restricted to the PMCs. In contrast to S. purp., in L. pictus the 130 Kd protein does not appear until the PMCs are formed. Hybrid embryos demonstrate a pattern of expression of the maternal species. These results suggest that early expression of 1223 antigen in S. purp. is due to utilization of maternal transcripts present in the egg. In both species later expression in PMCs appears to be the result of cell-type specific synthesis, perhaps encoded by embryonic transcripts

  1. Transformation and Crystallization Energetics of Synthetic and Biogenic Amorphous Calcium Carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Radha, A. V. [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States); Forbes, Tori Z. [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States); Killian, Christopher E. [Univ. of Wisconsin, Madison, WI (United States); Gilbert, P.U.P.A [Univ. of Wisconsin, Madison, WI (United States); Navrotsky, Alexandra [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States)

    2010-01-01

    Amorphous calcium carbonate (ACC) is a metastable phase often observed during low temperature inorganic synthesis and biomineralization. ACC transforms with aging or heating into a less hydrated form, and with time crystallizes to calcite or aragonite. The energetics of transformation and crystallization of synthetic and biogenic (extracted from California purple sea urchin larval spicules, Strongylocentrotus purpuratus) ACC were studied using isothermal acid solution calorimetry and differential scanning calorimetry. Transformation and crystallization of ACC can follow an energetically downhill sequence: more metastable hydrated ACC → less metastable hydrated ACC→anhydrous ACC ~ biogenic anhydrous ACC→vaterite → aragonite → calcite. In a given reaction sequence, not all these phases need to occur. The transformations involve a series of ordering, dehydration, and crystallization processes, each lowering the enthalpy (and free energy) of the system, with crystallization of the dehydrated amorphous material lowering the enthalpy the most. ACC is much more metastable with respect to calcite than the crystalline polymorphs vaterite or aragonite. The anhydrous ACC is less metastable than the hydrated, implying that the structural reorganization during dehydration is exothermic and irreversible. Dehydrated synthetic and anhydrous biogenic ACC are similar in enthalpy. The transformation sequence observed in biomineralization could be mainly energetically driven; the first phase deposited is hydrated ACC, which then converts to anhydrous ACC, and finally crystallizes to calcite. The initial formation of ACC may be a first step in the precipitation of calcite under a wide variety of conditions, including geological CO₂ sequestration.

  2. An equations of motion approach for open shell systems

    International Nuclear Information System (INIS)

    Yeager, D.L.; McKoy, V.

    1975-01-01

    A straightforward scheme is developed for extending the equations of motion formalism to systems with simple open shell ground states. Equations for open shell random phase approximation (RPA) are given for the cases of one electron outside of a closed shell in a nondegenerate molecular orbital and for the triplet ground state with two electrons outside of a closed shell in degenerate molecular orbitals. Applications to other open shells and extension of the open shell EOM to higher orders are both straightforward. Results for the open shell RPA for lithium atom and oxygen molecule are given

  3. Construction of carbon nanoflakes shell on CuO nanowires core as enhanced core/shell arrays anode of lithium ion batteries

    International Nuclear Information System (INIS)

    Cao, F.; Xia, X.H.; Pan, G.X.; Chen, J.; Zhang, Y.J.

    2015-01-01

    Highlights: • CuO/C core/shell nanowire arrays are prepared by electro-deposition + ALD method. • Carbon shell is favorable for structural stability. • CuO/C core/shell arrays show enhanced cycle stability and high capacity. - Abstract: Tailored metal oxide/carbon composite structures have attracted great attention due to potential synergistic effects and enhanced properties. In this work, novel CuO/C core/shell nanowire arrays are prepared by the combination of electro-deposition of CuO and atomic-layer-deposition-assisted formation of carbon nanoflakes shell. The CuO nanowires with diameters of ∼200 nm are homogenously coated by carbon nanoflakes shell. When evaluated as anode materials for lithium ion batteries (LIBs), compared to the unmodified CuO nanowire arrays, the CuO/C core/shell nanowire arrays exhibit improved electrochemical performances with higher capacity, better electrochemical reactivity and high-rate capability as well as superior cycling life (610 mAh g"−"1 at 0.5C after 290 cycles). The enhanced electrochemical performance is mainly attributed to the introduction of carbon flake shell in the core/shell nanowire arrays structure, which provides higher active material-electrolyte contact area, improved electrical conductivity, and better accommodation of volume change. The proposed method provides a new way for fabrication of high-performance metal oxides anodes of LIBs.

  4. A sea urchin Na(+)K(+)2Cl(-) cotransporter is involved in the maintenance of calcification-relevant cytoplasmic cords in Strongylocentrotus droebachiensis larvae.

    Science.gov (United States)

    Basse, Wiebke C; Gutowska, Magdalena A; Findeisen, Ulrike; Stumpp, Meike; Dupont, Sam; Jackson, Daniel J; Himmerkus, Nina; Melzner, Frank; Bleich, Markus

    2015-09-01

    The cellular mechanisms of calcification in sea urchin larvae are still not well understood. Primary mesenchyme cells within the larval body cavity form a syncytium to secrete CaCO3 spicules from intracellular amorphous CaCO3 (ACC) stores. We studied the role of Na(+)K(+)2Cl(-) cotransporter (NKCC) in intracellular ACC accumulation and larval spicule formation of Strongylocentrotus droebachiensis. First, we incubated growing larvae with three different loop diuretics (azosemide, bumetanide, and furosemide) and established concentration-response curves. All loop diuretics were able to inhibit calcification already at concentrations that specifically inhibit NKCC. Calcification was most effectively inhibited by azosemide (IC50=6.5 μM), while larval mortality and swimming ability were not negatively impacted by the treatment. The inhibition by bumetanide (IC50=26.4 μM) and furosemide (IC50=315.4 μM) resembled the pharmacological fingerprint of the mammalian NKCC1 isoform. We further examined the effect of azosemide on the maintenance of cytoplasmic cords and on the occurrence of calcification vesicles using fluorescent dyes (calcein, FM1-43). Fifty micromolars of azosemide inhibited the maintenance of cytoplasmic cords and resulted in increased calcein fluorescence within calcification vesicles. The expression of NKCC in S. droebachiensis was verified by PCR and Western blot with a specific NKCC antibody. In summary, the pharmacological profile of loop diuretics and their specific effects on calcification in sea urchin larvae suggest that they act by inhibition of NKCC via repression of cytoplasmic cord formation and maintenance. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Recent shell-model results for exotic nuclei

    Directory of Open Access Journals (Sweden)

    Utsuno Yusuke

    2014-03-01

    Full Text Available We report on our recent advancement in the shell model and its applications to exotic nuclei, focusing on the shell evolution and large-scale calculations with the Monte Carlo shell model (MCSM. First, we test the validity of the monopole-based universal interaction (VMU as a shell-model interaction by performing large-scale shell-model calculations in two different mass regions using effective interactions which partly comprise VMU. Those calculations are successful and provide a deeper insight into the shell evolution beyond the single-particle model, in particular showing that the evolution of the spin-orbit splitting due to the tensor force plays a decisive role in the structure of the neutron-rich N ∼ 28 region and antimony isotopes. Next, we give a brief overview of recent developments in MCSM, and show that it is applicable to exotic nuclei that involve many valence orbits. As an example of its applications to exotic nuclei, shape coexistence in 32Mg is examined.

  6. Off-shell distortions of multichannel atomic processes

    Science.gov (United States)

    Barrachina, R. O.; Clauser, C. F.

    2017-10-01

    Any multichannel problem can be reduced to a succession of two-body events. However, these basic building blocks of many-body theories do not correspond to elastic processes but are off-the-energy-shell. In view of this difficulty, the great majority of the Distorted-Wave models includes a subsidiary approximation where these off-shell terms are arbitrarily forced to lie on the energy shell. At a first glance, since the energy deficiency is negligible for high enough velocities, the on-shell assumption seems to be completely justified. However, for the case of Coulomb interactions, the two-body off-shell distortions have branch-point singularities on the on-shell limit. In this article we demonstrate that these singularities might produce sizeable distortions of multiple scattering amplitudes, mainly when dealing with ion-ion collisions. Finally, we propose a method of including these distortions that might lead to better results that removing them completely.

  7. Constraints for system specifications for the double-shell and single-shell tank systems

    International Nuclear Information System (INIS)

    SHAW, C.P.

    1999-01-01

    This is a supporting document for the Level 1 Double-Shell and Single-Shell System Specifications. The rationale for selection of specific regulatory constraining documents cited in the two system specifications is provided. many of the regulations have been implemented by the Project Hanford Management Contract procedures (HNF-PROs) and as such noted and traced back to their origins in State and Federal regulations

  8. Constraints for system specifications for the double-shell and single-shell tank systems

    Energy Technology Data Exchange (ETDEWEB)

    SHAW, C.P.

    1999-05-18

    This is a supporting document for the Level 1 Double-Shell and Single-Shell System Specifications. The rationale for selection of specific regulatory constraining documents cited in the two system specifications is provided. many of the regulations have been implemented by the Project Hanford Management Contract procedures (HNF-PROs) and as such noted and traced back to their origins in State and Federal regulations.

  9. Ionization of inner shells of atoms taking account of outer shell rearrangement

    International Nuclear Information System (INIS)

    Amusia, M.Ya.

    1977-01-01

    The application of the general many-body theory and methods formulated with its help, in particular, the so-called random phase approximation with exchange (RPAE) and the many-body perturbation theory (MBPT) makes possible a description of ionization processes for many outer and intermediate shells of a number of atoms. This investigation of outer- and intermediate-shell ionization by photons and electrons demonstrates the collective character of these processes and the possibility of describing them by RPAE. 28 references

  10. Stability of bubble nuclei through Shell-Effects

    OpenAIRE

    Dietrich, Klaus; Pomorski, Krzysztof

    1997-01-01

    We investigate the shell structure of bubble nuclei in simple phenomenological shell models and study their binding energy as a function of the radii and of the number of neutron and protons using Strutinsky's method. Shell effects come about, on the one hand, by the high degeneracy of levels with large angular momentum and, on the other, by the big energy gaps between states with a different number of radial nodes. Shell energies down to -40 MeV are shown to occur for certain magic nuclei. E...

  11. Obtainment of calcium carbonate from mussels shell

    International Nuclear Information System (INIS)

    Hamester, M.R.R.; Becker, D.

    2010-01-01

    The mussels and oyster shell are discarded at environment, and this accumulation is causing negative consequences to ecosystem. Calcium carbonate is main constituent of the shell chemical composition. Aiming to reduce environmental aggression and generate income to shellfish producer, there was the possibility of using these shells as an alternative to commercial calcium carbonate. For this physics, chemicals and thermal properties were evaluated, using X-ray fluorescence, thermogravimetric analysis, size distribution, abrasiveness and scanning electronic microscopy. The results indicate that mussels shells have an initial degradation temperature higher than commercial calcium carbonate e same lost weight behavior and 95% of shell chemical composition is calcium carbonate. The sample size distribution was influenced by grinding condition and time as well as its abrasiveness. (author)

  12. A design chart for long vacuum pipes and shells

    International Nuclear Information System (INIS)

    Krempetz, K.; Grimson, J.; Kelly, P.

    1986-01-01

    This paper presents a design chart to aid designers in the selection of a wall thickness for long cylindrical shells having atmospheric pressure outside the shell and a pressure less than atmospheric inside the shell. The chart indicates a conservative value for the minimum wall thickness for a given shell diameter and material when the shell is completely evacuated

  13. Statistical mechanics of microscopically thin thermalized shells

    Science.gov (United States)

    Kosmrlj, Andrej

    Recent explosion in fabrication of microscopically thin free standing structures made from graphene and other two-dimensional materials has led to a renewed interest in the mechanics of such structures in presence of thermal fluctuations. Since late 1980s it has been known that for flat solid sheets thermal fluctuations effectively increase the bending rigidity and reduce the bulk and shear moduli in a scale-dependent fashion. However, much is still unknown about the mechanics of thermalized flat sheets of complex geometries and about the mechanics of thermalized shells with non-zero background curvature. In this talk I will present recent development in the mechanics of thermalized ribbons, spherical shells and cylindrical tubes. Long ribbons are found to behave like hybrids between flat sheets with renormalized elastic constants and semi-flexible polymers, and these results can be used to predict the mechanics of graphene kirigami structures. Contrary to the anticipated behavior for ribbons, the non-zero background curvature of shells leads to remarkable novel phenomena. In shells, thermal fluctuations effectively generate negative surface tension, which can significantly reduce the critical buckling pressure for spherical shells and the critical axial load for cylindrical tubes. For large shells this thermally generated load becomes big enough to spontaneously crush spherical shells and cylindrical tubes even in the absence of external loads. I will comment on the relevance for crushing of microscopic shells (viral capsids, bacteria, microcapsules) due to osmotic shocks and for crushing of nanotubes.

  14. Shell model in large spaces and statistical spectroscopy

    International Nuclear Information System (INIS)

    Kota, V.K.B.

    1996-01-01

    For many nuclear structure problems of current interest it is essential to deal with shell model in large spaces. For this, three different approaches are now in use and two of them are: (i) the conventional shell model diagonalization approach but taking into account new advances in computer technology; (ii) the shell model Monte Carlo method. A brief overview of these two methods is given. Large space shell model studies raise fundamental questions regarding the information content of the shell model spectrum of complex nuclei. This led to the third approach- the statistical spectroscopy methods. The principles of statistical spectroscopy have their basis in nuclear quantum chaos and they are described (which are substantiated by large scale shell model calculations) in some detail. (author)

  15. Mechanical stability of cylindrical thin-shell wormholes

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M. [University of the Punjab, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)

    2013-04-15

    In this paper, we apply the cut and paste procedure to the charged black string for the construction of a thin-shell wormhole. We consider the Darmois-Israel formalism to determine the surface stresses of the shell. We take the Chaplygin gas to deal with the matter distribution on shell. The radial perturbation approach (preserving the symmetry) is used to investigate the stability of static solutions. We conclude that stable static solutions exist both for uncharged and charged black string thin-shell wormholes for particular values of the parameters. (orig.)

  16. Horizon shells and BMS-like soldering transformations

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Matthias [Albert Einstein Center for Fundamental Physics,Institute for Theoretical Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland); O’Loughlin, Martin [University of Nova Gorica,Vipavska 13, 5000 Nova Gorica (Slovenia)

    2016-03-07

    We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, and these solderings create non-trivial horizon shells containing both massless matter and impulsive gravitational wave components. We also rephrase this result in the language of Carrollian symmetry groups. To illustrate this phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild black hole (with equal interior and exterior mass), uncovering a rich classical structure at the horizon and deriving an explicit expression for the general horizon shell energy-momentum tensor. In the special case of BMS-like soldering supertranslations we find a conserved shell-energy that is strikingly similar to the standard expression for asymptotic BMS supertranslation charges, suggesting a direct relation between the physical properties of these horizon shells and the recently proposed BMS supertranslation hair of a black hole.

  17. Axisymmetric vibrations of thick shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)

  18. A finite element for plates and shells

    International Nuclear Information System (INIS)

    Muller, A.; Feijoo, R.A.; Bevilacqua, L.

    1981-08-01

    A simple triangular finite element for plates and shells, is presented. Since the rotation fields are assumed independent of the displacement fields, the element allows one to solve thick shells problems. In the limit for thin shell, the Kirchoff-Love hypothesis is automatically satisfied, thus enlarging its range of application. (Author) [pt

  19. Shell model Monte Carlo methods

    International Nuclear Information System (INIS)

    Koonin, S.E.

    1996-01-01

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of γ-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs

  20. Semiclassical shell structure in rotating Fermi systems

    International Nuclear Information System (INIS)

    Magner, A. G.; Sitdikov, A. S.; Khamzin, A. A.; Bartel, J.

    2010-01-01

    The collective moment of inertia is derived analytically within the cranking model for any rotational frequency of the harmonic-oscillator potential well and at a finite temperature. Semiclassical shell-structure components of the collective moment of inertia are obtained for any potential by using the periodic-orbit theory. We found semiclassically their relation to the free-energy shell corrections through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. The shell effects in the moment of inertia exponentially disappear with increasing temperature. For the case of the harmonic-oscillator potential, one observes a perfect agreement of the semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures.

  1. Core@shell@shell structured carbon-based magnetic ternary nanohybrids: Synthesis and their enhanced microwave absorption properties

    Science.gov (United States)

    Yang, Erqi; Qi, Xiaosi; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

    2018-05-01

    High encapsulation efficiency of core@shell@shell structured carbon-based magnetic ternary nanohybrids have been synthesized in high yield by chemical vapor deposition of acetylene directly over octahedral-shaped Fe2O3 nanoparticles. By controlling the pyrolysis temperature, Fe3O4@Fe3C@carbon nanotubes (CNTs) and Fe@Fe3C@CNTs ternary nanohybrids could be selectively produced. The optimal RL values for the as-prepared ternary nanohybrids could reach up to ca. -46.7, -52.7 and -29.5 dB, respectively. The excellent microwave absorption properties of the obtaiend ternary nanohybrids were proved to ascribe to the quarter-wavelength matching model. Moreover, the as-prepared Fe@Fe3C@CNTs ternary nanohybrids displayed remarkably enhanced EM wave absorption capabilities compared to Fe3O4@Fe3C@CNTs due to their excellent dielectric loss abilities, good complementarities between the dielectric loss and the magnetic loss, and high attenuation constant. Generally, this strategy can be extended to explore other categories of core@shell or core@shell@shell structured carbon-based nanohybrids, which is very beneficial to accelerate the advancements of high performance MAMs.

  2. Folding of non-Euclidean curved shells

    Science.gov (United States)

    Bende, Nakul; Evans, Arthur; Innes-Gold, Sarah; Marin, Luis; Cohen, Itai; Santangelo, Christian; Hayward, Ryan

    2015-03-01

    Origami-based folding of 2D sheets has been of recent interest for a variety of applications ranging from deployable structures to self-folding robots. Though folding of planar sheets follows well-established principles, folding of curved shells involves an added level of complexity due to the inherent influence of curvature on mechanics. In this study, we use principles from differential geometry and thin shell mechanics to establish fundamental rules that govern folding of prototypical creased shells. In particular, we show how the normal curvature of a crease line controls whether the deformation is smooth or discontinuous, and investigate the influence of shell thickness and boundary conditions. We show that snap-folding of shells provides a route to rapid actuation on time-scales dictated by the speed of sound. The simple geometric design principles developed can be applied at any length-scale, offering potential for bio-inspired soft actuators for tunable optics, microfluidics, and robotics. This work was funded by the National Science Foundation through EFRI ODISSEI-1240441 with additional support to S.I.-G. through the UMass MRSEC DMR-0820506 REU program.

  3. Double shell planar experiments on OMEGA

    Science.gov (United States)

    Dodd, E. S.; Merritt, E. C.; Palaniyappan, S.; Montgomery, D. S.; Daughton, W. S.; Schmidt, D. W.; Cardenas, T.; Wilson, D. C.; Loomis, E. N.; Batha, S. H.; Ping, Y.; Smalyuk, V. A.; Amendt, P. A.

    2017-10-01

    The double shell project is aimed at fielding neutron-producing capsules at the National Ignition Facility (NIF), in which an outer low-Z ablator collides with an inner high-Z shell to compress the fuel. However, understanding these targets experimentally can be challenging when compared with conventional single shell targets. Halfraum-driven planar targets at OMEGA are being used to study physics issues important to double shell implosions outside of a convergent geometry. Both VISAR and radiography through a tube have advantages over imaging through the hohlraum and double-shell capsule at NIF. A number physics issues are being studied with this platform that include 1-d and higher dimensional effects such as defect-driven hydrodynamic instabilities from engineering features. Additionally, the use of novel materials with controlled density gradients require study in easily diagnosed 1-d systems. This work ultimately feeds back into the NIF capsule platform through manufacturing tolerances set using data from OMEGA. Supported under the US DOE by the LANS, LLC under contract DE-AC52-06NA25396. LA-UR-17-25386.

  4. Synthesis of parallel and antiparallel core-shell triangular nanoparticles

    Science.gov (United States)

    Bhattacharjee, Gourab; Satpati, Biswarup

    2018-04-01

    Core-shell triangular nanoparticles were synthesized by seed mediated growth. Using triangular gold (Au) nanoparticle as template, we have grown silver (Ag) shellto get core-shell nanoparticle. Here by changing the chemistry we have grown two types of core-shell structures where core and shell is having same symmetry and also having opposite symmetry. Both core and core-shell nanoparticles were characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) to know the crystal structure and composition of these synthesized core-shell nanoparticles. From diffraction pattern analysis and energy filtered TEM (EFTEM) we have confirmed the crystal facet in core is responsible for such two dimensional growth of core-shell nanostructures.

  5. The evolution of mollusc shells.

    Science.gov (United States)

    McDougall, Carmel; Degnan, Bernard M

    2018-05-01

    Molluscan shells are externally fabricated by specialized epithelial cells on the dorsal mantle. Although a conserved set of regulatory genes appears to underlie specification of mantle progenitor cells, the genes that contribute to the formation of the mature shell are incredibly diverse. Recent comparative analyses of mantle transcriptomes and shell proteomes of gastropods and bivalves are consistent with shell diversity being underpinned by a rapidly evolving mantle secretome (suite of genes expressed in the mantle that encode secreted proteins) that is the product of (a) high rates of gene co-option into and loss from the mantle gene regulatory network, and (b) the rapid evolution of coding sequences, particular those encoding repetitive low complexity domains. Outside a few conserved genes, such as carbonic anhydrase, a so-called "biomineralization toolkit" has yet to be discovered. Despite this, a common suite of protein domains, which are often associated with the extracellular matrix and immunity, appear to have been independently and often uniquely co-opted into the mantle secretomes of different species. The evolvability of the mantle secretome provides a molecular explanation for the evolution and diversity of molluscan shells. These genomic processes are likely to underlie the evolution of other animal biominerals, including coral and echinoderm skeletons. This article is categorized under: Comparative Development and Evolution > Regulation of Organ Diversity Comparative Development and Evolution > Evolutionary Novelties. © 2018 Wiley Periodicals, Inc.

  6. Deriving the nuclear shell model from first principles

    Science.gov (United States)

    Barrett, Bruce R.; Dikmen, Erdal; Vary, James P.; Maris, Pieter; Shirokov, Andrey M.; Lisetskiy, Alexander F.

    2014-09-01

    The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. Supported by the US NSF under Grant No. 0854912, the US DOE under

  7. Unified description of pf-shell nuclei by the Monte Carlo shell model calculations

    Energy Technology Data Exchange (ETDEWEB)

    Mizusaki, Takahiro; Otsuka, Takaharu [Tokyo Univ. (Japan). Dept. of Physics; Honma, Michio

    1998-03-01

    The attempts to solve shell model by new methods are briefed. The shell model calculation by quantum Monte Carlo diagonalization which was proposed by the authors is a more practical method, and it became to be known that it can solve the problem with sufficiently good accuracy. As to the treatment of angular momentum, in the method of the authors, deformed Slater determinant is used as the basis, therefore, for making angular momentum into the peculiar state, projected operator is used. The space determined dynamically is treated mainly stochastically, and the energy of the multibody by the basis formed as the result is evaluated and selectively adopted. The symmetry is discussed, and the method of decomposing shell model space into dynamically determined space and the product of spin and isospin spaces was devised. The calculation processes are shown with the example of {sup 50}Mn nuclei. The calculation of the level structure of {sup 48}Cr with known exact energy can be done with the accuracy of peculiar absolute energy value within 200 keV. {sup 56}Ni nuclei are the self-conjugate nuclei of Z=N=28. The results of the shell model calculation of {sup 56}Ni nucleus structure by using the interactions of nuclear models are reported. (K.I.)

  8. Aqueous-phase synthesis and color-tuning of core/shell/shell inorganic nanocrystals consisting of ZnSe, (Cu, Mn)-doped ZnS, and ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jongwan; Yoon, Sujin [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of); Kim, Felix Sunjoo, E-mail: fskim@cau.ac.kr [School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul, 156-756 (Korea, Republic of); Kim, Nakjoong, E-mail: kimnj@hanyang.ac.kr [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of)

    2016-06-25

    We report synthesis of colloidal nanocrystals based on ZnSe core, (Cu,Mn)-doped ZnS inner-shell, and ZnS outer-shell by using an eco-friendly method and their optical properties. Synthesis of core/shell/shell nanocrystals was performed by using a one-pot/three-step colloidal method with 3-mercaptopropionic acid as a stabilizer in aqueous phase at low temperature. A double-shell structure was employed with inner-shell as a host for doping and outer-shell as a passivation layer for covering surface defects. Copper and manganese were introduced as single- or co-dopants during inner-shell formation, providing an effective means to control the emission color of the nanocrystals. The synthesized nanocrystals showed fluorescent emission ranging from blue to green, to white, and to orange, adjusted by doping components, amounts, and ratios. The photoluminescence quantum yields of the core/doped-shell/shell nanocrystals approached 36%. - Highlights: • ZnSe/ZnS:(Cu,Ms)/ZnS core/(doped)shell/shell nanocrystals were synthesized in an aqueous phase. • Emission color of nanocrystals was controlled from blue to white to orange by adjusting the atomic ratio of Cu and Mn co-dopants. • Photoluminescence quantum yields of the colloidal nanocrystals approached 36%.

  9. Conventional shell model: some issues

    International Nuclear Information System (INIS)

    Vallieres, M.; Pan, X.W.; Feng, D.H.; Novoselsky, A.

    1997-01-01

    We discuss some important issues in shell-model calculations related to the effective interactions used in different regions of the periodic table; in particular the quality of different interactions is discussed, as well as the mass dependence of the interactions. Mention is made of the recently developed Drexel University shell-model (DUSM). (orig.)

  10. Modeling complicated rheological behaviors in encapsulating shells of lipid-coated microbubbles accounting for nonlinear changes of both shell viscosity and elasticity.

    Science.gov (United States)

    Li, Qian; Matula, Thomas J; Tu, Juan; Guo, Xiasheng; Zhang, Dong

    2013-02-21

    It has been accepted that the dynamic responses of ultrasound contrast agent (UCA) microbubbles will be significantly affected by the encapsulating shell properties (e.g., shell elasticity and viscosity). In this work, a new model is proposed to describe the complicated rheological behaviors in an encapsulating shell of UCA microbubbles by applying the nonlinear 'Cross law' to the shell viscous term in the Marmottant model. The proposed new model was verified by fitting the dynamic responses of UCAs measured with either a high-speed optical imaging system or a light scattering system. The comparison results between the measured radius-time curves and the numerical simulations demonstrate that the 'compression-only' behavior of UCAs can be successfully simulated with the new model. Then, the shell elastic and viscous coefficients of SonoVue microbubbles were evaluated based on the new model simulations, and compared to the results obtained from some existing UCA models. The results confirm the capability of the current model for reducing the dependence of bubble shell parameters on the initial bubble radius, which indicates that the current model might be more comprehensive to describe the complex rheological nature (e.g., 'shear-thinning' and 'strain-softening') in encapsulating shells of UCA microbubbles by taking into account the nonlinear changes of both shell elasticity and shell viscosity.

  11. Modeling complicated rheological behaviors in encapsulating shells of lipid-coated microbubbles accounting for nonlinear changes of both shell viscosity and elasticity

    International Nuclear Information System (INIS)

    Li Qian; Tu Juan; Guo Xiasheng; Zhang Dong; Matula, Thomas J

    2013-01-01

    It has been accepted that the dynamic responses of ultrasound contrast agent (UCA) microbubbles will be significantly affected by the encapsulating shell properties (e.g., shell elasticity and viscosity). In this work, a new model is proposed to describe the complicated rheological behaviors in an encapsulating shell of UCA microbubbles by applying the nonlinear ‘Cross law’ to the shell viscous term in the Marmottant model. The proposed new model was verified by fitting the dynamic responses of UCAs measured with either a high-speed optical imaging system or a light scattering system. The comparison results between the measured radius–time curves and the numerical simulations demonstrate that the ‘compression-only’ behavior of UCAs can be successfully simulated with the new model. Then, the shell elastic and viscous coefficients of SonoVue microbubbles were evaluated based on the new model simulations, and compared to the results obtained from some existing UCA models. The results confirm the capability of the current model for reducing the dependence of bubble shell parameters on the initial bubble radius, which indicates that the current model might be more comprehensive to describe the complex rheological nature (e.g., ‘shear-thinning’ and ‘strain-softening’) in encapsulating shells of UCA microbubbles by taking into account the nonlinear changes of both shell elasticity and shell viscosity. (paper)

  12. Molluscan shell evolution with review of shell calcification hypothesis

    Czech Academy of Sciences Publication Activity Database

    Furuhashi, T.; Schwarzinger, C.; Mikšík, Ivan; Smrž, Miloslav; Beran, A.

    2009-01-01

    Roč. 154, č. 3 (2009), s. 351-371 ISSN 1096-4959 Institutional research plan: CEZ:AV0Z50110509 Keywords : mollusca * shell * biomineralization Subject RIV: CE - Biochemistry Impact factor: 1.607, year: 2009

  13. Inactivation of Vibrio cholerae O1 El Tor inoculated into Peruvian ''choro'' mussels (Aulacomya ater) and two species of clams (Argopecten purpuratus and Gari solida) using medium-dose irradiation

    International Nuclear Information System (INIS)

    Torres, Z.; Bernuy, B.; Kahn, G.; Zapata, G.; Vivanco, M.; Guzman, E.; Leon, R.

    2001-01-01

    The radiation decimal reduction dose (D 10 ) for Vibrio cholerae O1 biotype El Tor inoculated through the natural feeding system into three species of bivalve mollusks from the Peruvian Pacific coast: ''choro'' mussels (Aulacome ater), ''abanico'' clams (Argopecten purpuratus), and common clams (Gari solida), was determined in vivo. The D 10 value obtained in vivo was 0.14 kGy in all mollusks tested. Concurrent studies conducted to determine the potential use of irradiation to extend the microbiological shelf-life of the mollusks during post-irradiation storage at 0-1 deg. C indicated that a dose of 1.0 kGy was optimal for choro mussels and abanico clams, whereas 2.0 kGy produced the best results when treating common clams. Shelf-life extension thus achieved was 31 days for choro mussels, 16 days for abanico clams, and 21 days for common clams. Non-irradiated control samples of all mollusks spoiled after 17 days of refrigerated storage. There were no significant (p<.05) adverse effects from the application of the optimal radiation treatments on the sensory characteristics (i.e. appearance, odor, flavor, and texture) of the mollusks. Total volatile basic nitrogen (VBN) and pH values were examined for use as indexes of seafood freshness. (author)

  14. Vibrio cholerae Colonization of Soft-Shelled Turtles.

    Science.gov (United States)

    Wang, Jiazheng; Yan, Meiying; Gao, He; Lu, Xin; Kan, Biao

    2017-07-15

    Vibrio cholerae is an important human pathogen and environmental microflora species that can both propagate in the human intestine and proliferate in zooplankton and aquatic organisms. Cholera is transmitted through food and water. In recent years, outbreaks caused by V. cholerae -contaminated soft-shelled turtles, contaminated mainly with toxigenic serogroup O139, have been frequently reported, posing a new foodborne disease public health problem. In this study, the colonization by toxigenic V. cholerae on the body surfaces and intestines of soft-shelled turtles was explored. Preferred colonization sites on the turtle body surfaces, mainly the carapace and calipash of the dorsal side, were observed for the O139 and O1 strains. Intestinal colonization was also found. The colonization factors of V. cholerae played different roles in the colonization of the soft-shelled turtle's body surface and intestine. Mannose-sensitive hemagglutinin (MSHA) of V. cholerae was necessary for body surface colonization, but no roles were found for toxin-coregulated pili (TCP) or N -acetylglucosamine-binding protein A (GBPA). Both TCP and GBPA play important roles for colonization in the intestine, whereas the deletion of MSHA revealed only a minor colonization-promoting role for this factor. Our study demonstrated that V. cholerae can colonize the surfaces and the intestines of soft-shelled turtles and indicated that the soft-shelled turtles played a role in the transmission of cholera. In addition, this study showed that the soft-shelled turtle has potential value as an animal model in studies of the colonization and environmental adaption mechanisms of V. cholerae in aquatic organisms. IMPORTANCE Cholera is transmitted through water and food. Soft-shelled turtles contaminated with Vibrio cholerae (commonly the serogroup O139 strains) have caused many foodborne infections and outbreaks in recent years, and they have become a foodborne disease problem. Except for epidemiological

  15. Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells.

    Science.gov (United States)

    Dolan, Laurie; Matulka, Ray; Worn, Jeffrey; Nizio, John

    2016-01-01

    Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control), 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only) that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week) no observable adverse effect level (NOAEL) of 150 000 ppm in rats and is not genotoxic at the doses analyzed.

  16. Collapse analysis of toroidal shell

    International Nuclear Information System (INIS)

    Pomares, R.J.

    1990-01-01

    This paper describes a study performed to determine the collapse characteristics of a toroidal shell using finite element method (FEM) analysis. The study also included free drop testing of a quarter scale prototype to verify the analytical results. The full sized toroidal shell has a 24-inch toroidal diameter with a 24-inch tubal diameter. The shell material is type 304 strainless steel. The toroidal shell is part of the GE Model 2000 transportation packaging, and acts as an energy absorbing device. The analyses performed were on a full sized and quarter scaled models. The finite element program used in all analyses was the LIBRA code. The analytical procedure used both the elasto-plastic and large displacement options within the code. The loading applied in the analyses corresponded to an impact of an infinite rigid plane oriented normal to the drop direction vector. The application of the loading continued incrementally until the work performed by the deforming structure equalled the kinetic energy developed in the free fall. The comparison of analysis and test results showed a good correlation

  17. Micromagnetic studies of three-dimensional pyramidal shell structures

    International Nuclear Information System (INIS)

    Knittel, A; Franchin, M; Fischbacher, T; Fangohr, H; Nasirpouri, F; Bending, S J

    2010-01-01

    We present a systematic numerical analysis of the magnetic properties of pyramidal-shaped core-shell structures in a size range below 400 nm. These are three-dimensional structures consisting of a ferromagnetic shell which is grown on top of a non-magnetic core. The standard micromagnetic model without the magnetocrystalline anisotropy term is used to describe the properties of the shell. We vary the thickness of the shell between the limiting cases of an ultra-thin shell and a conventional pyramid and delineate different stable magnetic configurations. We find different kinds of single-domain states, which predominantly occur at smaller system sizes. In analogy to equivalent states in thin square films we term these onion, flower, C and S states. At larger system sizes, we also observe two types of vortex states, which we refer to as symmetric and asymmetric vortex states. For a classification of the observed states, we derive a phase diagram that specifies the magnetic ground state as a function of structure size and shell thickness. The transitions between different ground states can be understood qualitatively. We address the issue of metastability by investigating the stability of all occurring configurations for different shell thicknesses. For selected geometries and directions hysteresis measurements are analysed and discussed. We observe that the magnetic behaviour changes distinctively in the limit of ultra-thin shells. The study has been motivated by the recent progress made in the growth of faceted core-shell structures.

  18. Snap-Through Buckling Problem of Spherical Shell Structure

    Directory of Open Access Journals (Sweden)

    Sumirin Sumirin

    2014-12-01

    Full Text Available This paper presents results of a numerical study on the nonlinear behavior of shells undergoing snap-through instability. This research investigates the problem of snap-through buckling of spherical shells applying nonlinear finite element analysis utilizing ANSYS Program. The shell structure was modeled by axisymmetric thin shell of finite elements. Shells undergoing snap-through buckling meet with significant geometric change of their physical configuration, i.e. enduring large deflections during their deformation process. Therefore snap-through buckling of shells basically is a nonlinear problem. Nonlinear numerical operations need to be applied in their analysis. The problem was solved by a scheme of incremental iterative procedures applying Newton-Raphson method in combination with the known line search as well as the arc- length methods. The effects of thickness and depth variation of the shell is taken care of by considering their geometrical parameter l. The results of this study reveal that spherical shell structures subjected to pressure loading experience snap-through instability for values of l≥2.15. A form of ‘turn-back’ of the load-displacement curve took place at load levels prior to the achievement of the critical point. This phenomenon was observed for values of l=5.0 to l=7.0.

  19. Nanostructured core-shell electrode materials for electrochemical capacitors

    Science.gov (United States)

    Jiang, Long-bo; Yuan, Xing-zhong; Liang, Jie; Zhang, Jin; Wang, Hou; Zeng, Guang-ming

    2016-11-01

    Core-shell nanostructure represents a unique system for applications in electrochemical energy storage devices. Owing to the unique characteristics featuring high power delivery and long-term cycling stability, electrochemical capacitors (ECs) have emerged as one of the most attractive electrochemical storage systems since they can complement or even replace batteries in the energy storage field, especially when high power delivery or uptake is needed. This review aims to summarize recent progress on core-shell nanostructures for advanced supercapacitor applications in view of their hierarchical architecture which not only create the desired hierarchical porous channels, but also possess higher electrical conductivity and better structural mechanical stability. The core-shell nanostructures include carbon/carbon, carbon/metal oxide, carbon/conducting polymer, metal oxide/metal oxide, metal oxide/conducting polymer, conducting polymer/conducting polymer, and even more complex ternary core-shell nanoparticles. The preparation strategies, electrochemical performances, and structural stabilities of core-shell materials for ECs are summarized. The relationship between core-shell nanostructure and electrochemical performance is discussed in detail. In addition, the challenges and new trends in core-shell nanomaterials development have also been proposed.

  20. Shell model Monte Carlo methods

    International Nuclear Information System (INIS)

    Koonin, S.E.; Dean, D.J.; Langanke, K.

    1997-01-01

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; the resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo (SMMC) methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, the thermal and rotational behavior of rare-earth and γ-soft nuclei, and the calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. (orig.)

  1. Computed tomographic evaluation of dinosar egg shell integrity

    International Nuclear Information System (INIS)

    Jones, J.C.; Greenberg, W.; Ayers, S.

    1998-01-01

    The purpose of this study was to determine whether computed tomography (CT) could be used to identify hatching holes in partially embedded dinosaur eggs. One Faveololithus and two Dendroolithus eggs were examined using a fourth generation CT scanner. The eggs were partially embedded in a fossilized sediment matrix, with the exposed portion of the shell appearing intact. In CT images of all three eggs, the shells appeared hyperdense relative to the matrix. Hatching holes were visible as large gaps in the embedded portion of the shell, with inwardly displaced shell fragments. It was concluded that CT is an effective technique for nondestructively assessing dinosaur egg shell integrity

  2. Method of fabricating nested shells and resulting product

    Science.gov (United States)

    Henderson, Timothy M.; Kool, Lawrence B.

    1982-01-01

    A multiple shell structure and a method of manufacturing such structure wherein a hollow glass microsphere is surface treated in an organosilane solution so as to render the shell outer surface hydrophobic. The surface treated glass shell is then suspended in the oil phase of an oil-aqueous phase dispersion. The oil phase includes an organic film-forming monomer, a polymerization initiator and a blowing agent. A polymeric film forms at each phase boundary of the dispersion and is then expanded in a blowing operation so as to form an outer homogeneously integral monocellular substantially spherical thermoplastic shell encapsulating an inner glass shell of lesser diameter.

  3. Shell model and spectroscopic factors

    International Nuclear Information System (INIS)

    Poves, P.

    2007-01-01

    In these lectures, I introduce the notion of spectroscopic factor in the shell model context. A brief review is given of the present status of the large scale applications of the Interacting Shell Model. The spectroscopic factors and the spectroscopic strength are discussed for nuclei in the vicinity of magic closures and for deformed nuclei. (author)

  4. Optimal designs of mollusk shells from bivalves to snails.

    Science.gov (United States)

    Okabe, Takuya; Yoshimura, Jin

    2017-02-10

    Bivalve, ammonite and snail shells are described by a small number of geometrical parameters. Raup noted that the vast majority of theoretically possible shell forms do not occur in nature. The constraint factors that regulate the biased distribution of natural form have long since been an open problem in evolution. The problem of whether natural shell form is a result of optimization remains unsolved despite previous attempts. Here we solve this problem by considering the scaling exponent of shell thickness as a morphological parameter. The scaling exponent has a drastic effect on the optimal design of shell shapes. The observed characteristic shapes of natural shells are explained in a unified manner as a result of optimal utilization of shell material resources, while isometric growth in thickness leads to impossibly tight coiling.

  5. Adaptative mixed methods to axisymmetric shells

    International Nuclear Information System (INIS)

    Malta, S.M.C.; Loula, A.F.D.; Garcia, E.L.M.

    1989-09-01

    The mixed Petrov-Galerkin method is applied to axisymmetric shells with uniform and non uniform meshes. Numerical experiments with a cylindrical shell showed a significant improvement in convergence and accuracy with adaptive meshes. (A.C.A.S.) [pt

  6. Inner shell ionization accompanying nuclear collisions

    International Nuclear Information System (INIS)

    Sujkowski, Z.

    1987-01-01

    Selected phenomena leading to inner shell ionization and being of relevance for nuclear physics are discussed. The selection emphasizes the K-shell ionization induced in head-on collisions by fast light and medium-heavy ions. Cross-sections are reviewed. Effects of multiple inner shell ionization on the K X-ray spectra are illustrated with recent results. Implications for nuclear experiments are noted. Use of atomic observables as clocks for proton induced nuclear reactions is reviewed. Prospects for H.I. reactions are discussed. Preliminary experimental results on the direct K-shell ionization accompanying H.I. fusion reactions are presented. The post-collisional K-shell ionization due to internal conversion of γ-rays is discussed as the dominating contribution to the ionization for residues of dissipative nuclear reactions with Z > 40. Systematics of the corresponding K X-ray multiplicities are presented for rotational nuclei. These multiplicity values can be used for determining cross-sections for e.g. incomplete fusion reactions. Examples of such applications are given. Also discussed is the use of target K X-rays for normalization purposes and of the post-collisional, residue K X-rays in the studies of high spin phenomena. 96 references, 35 figures, 3 tables

  7. Process to make core-shell structured nanoparticles

    Science.gov (United States)

    Luhrs, Claudia; Phillips, Jonathan; Richard, Monique N

    2014-01-07

    Disclosed is a process for making a composite material that contains core-shell structured nanoparticles. The process includes providing a precursor in the form of a powder a liquid and/or a vapor of a liquid that contains a core material and a shell material, and suspending the precursor in an aerosol gas to produce an aerosol containing the precursor. In addition, the process includes providing a plasma that has a hot zone and passing the aerosol through the hot zone of the plasma. As the aerosol passes through the hot zone of the plasma, at least part of the core material and at least part of the shell material in the aerosol is vaporized. Vapor that contains the core material and the shell material that has been vaporized is removed from the hot zone of the plasma and allowed to condense into core-shell structured nanoparticles.

  8. Bending stresses in Facetted Glass Shells

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik

    2008-01-01

    A shell structure of glass combines a highly effective structural principle with a material of optimal permeability to light. A facetted shell structure has a piecewise plane geometry, and together the facets form an approximation to a curved surface. A distributed load on a plane-based facetted...... structure will locally cause bending moments in the loaded facets. The bending stresses are dependent on the stiffness of the joints. Approximate solutions are developed to estimate the magnitude of the bending stresses. A FE-model of a facetted glass shell structure is used to validate the expressions...

  9. Amplitude structure of off-shell processes

    International Nuclear Information System (INIS)

    Fearing, H.W.; Goldstein, G.R.; Moravcsik, M.J.

    1984-01-01

    The structure of M matrices, or scattering amplitudes, and of potentials for off-shell processes is discussed with the objective of determining how one can obtain information on off-shell amplitudes of a process in terms of the physical observables of a larger process in which the first process is embedded. The procedure found is inevitably model dependent, but within a particular model for embedding, a determination of the physically measurable amplitudes of the larger process is able to yield a determination of the off-shell amplitudes of the embedded process

  10. Type I Shell Galaxies as a Test of Gravity Models

    Energy Technology Data Exchange (ETDEWEB)

    Vakili, Hajar; Rahvar, Sohrab [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Kroupa, Pavel, E-mail: vakili@physics.sharif.edu [Helmholtz-Institut für Strahlen-und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn (Germany)

    2017-10-10

    Shell galaxies are understood to form through the collision of a dwarf galaxy with an elliptical galaxy. Shell structures and kinematics have been noted to be independent tools to measure the gravitational potential of the shell galaxies. We compare theoretically the formation of shells in Type I shell galaxies in different gravity theories in this work because this is so far missing in the literature. We include Newtonian plus dark halo gravity, and two non-Newtonian gravity models, MOG and MOND, in identical initial systems. We investigate the effect of dynamical friction, which by slowing down the dwarf galaxy in the dark halo models limits the range of shell radii to low values. Under the same initial conditions, shells appear on a shorter timescale and over a smaller range of distances in the presence of dark matter than in the corresponding non-Newtonian gravity models. If galaxies are embedded in a dark matter halo, then the merging time may be too rapid to allow multi-generation shell formation as required by observed systems because of the large dynamical friction effect. Starting from the same initial state, the observation of small bright shells in the dark halo model should be accompanied by large faint ones, while for the case of MOG, the next shell generation patterns iterate with a specific time delay. The first shell generation pattern shows a degeneracy with the age of the shells and in different theories, but the relative distance of the shells and the shell expansion velocity can break this degeneracy.

  11. Fossil shell emission in dying radio loud AGNs

    Science.gov (United States)

    Kino, M.; Ito, H.; Kawakatu, N.; Orienti, M.; Nagai, H.; Wajima, K.; Itoh, R.

    2016-02-01

    We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolution of shells after stopping the jet energy injection. We find that the shell emission overwhelms that of the radio lobes soon after stopping the jet energy injection because fresh electrons are continuously supplied into the shell via the forward shock, while the radio lobes rapidly fade out without jet energy injection. We find that such fossil shells can be a new class of target sources for SKA telescope. Next, we apply the model to the nearby radio source 3C84. Then, we find that the fossil shell emission in 3C84 is less luminous in the radio band while it is bright in the TeV γ-ray band and can be detectable by CTA. Data from STELLA

  12. Inner-shell excitation of alkali-metal atoms

    International Nuclear Information System (INIS)

    Tiwary, S.N.

    1987-06-01

    Inner-shell excitation of alkali-metal atoms, which leads to auto-ionization, is reviewed. The validity of quantum mechanical approximation is analyzed and the importance of exchange and correlation is demonstrated. Basic difficulties in making accurate calculations for inner-shell excitation process are discussed. Suggestions are made for further study of inner-shell process in atoms and ions. (author). 26 refs, 4 figs, 1 tab

  13. Effect of shell thickness on the exchange bias blocking temperature and coercivity in Co-CoO core-shell nanoparticles

    Science.gov (United States)

    Thomas, S.; Reethu, K.; Thanveer, T.; Myint, M. T. Z.; Al-Harthi, S. H.

    2017-08-01

    The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.

  14. Shell Thickness Dependence of Interparticle Energy Transfer in Core-Shell ZnSe/ZnSe Quantum Dots Doping with Europium

    Science.gov (United States)

    Liu, Ni; Li, Shuxin; Wang, Caifeng; Li, Jie

    2018-04-01

    Low-toxic core-shell ZnSe:Eu/ZnS quantum dots (QDs) were prepared through two steps in water solution: nucleation doping and epitaxial shell grown. The structural and morphological characteristics of ZnSe/ZnS:Eu QDs with different shell thickness were explored by transmission electron microscopy (TEM) and X-ray diffraction (XRD) results. The characteristic photoluminescence (PL) intensity of Eu ions was enhanced whereas that of band-edge luminescence and defect-related luminescence of ZnSe QDs was decreased with increasing shell thickness. The transformation of PL intensity revealed an efficient energy transfer process between ZnSe and Eu. The PL intensity ratio of Eu ions ( I 613) to ZnSe QDs ( I B ) under different shell thickness was systemically analyzed by PL spectra and time-resolved PL spectra. The obtained results were in agreement with the theory analysis results by the kinetic theory of energy transfer, revealing that energy was transmitted in the form of dipole-electric dipole interaction. This particular method of adjusting luminous via changing the shell thickness can provide valuable insights towards the fundamental understanding and application of QDs in the field of optoelectronics.

  15. Active constrained layer damping treatments for shell structures: a deep-shell theory, some intuitive results, and an energy analysis

    Science.gov (United States)

    Shen, I. Y.

    1997-02-01

    This paper studies vibration control of a shell structure through use of an active constrained layer (ACL) damping treatment. A deep-shell theory that assumes arbitrary Lamé parameters 0964-1726/6/1/011/img1 and 0964-1726/6/1/011/img2 is first developed. Application of Hamilton's principle leads to the governing Love equations, the charge equation of electrostatics, and the associated boundary conditions. The Love equations and boundary conditions imply that the control action of the ACL for shell treatments consists of two components: free-end boundary actuation and membrane actuation. The free-end boundary actuation is identical to that of beam and plate ACL treatments, while the membrane actuation is unique to shell treatments as a result of the curvatures of the shells. In particular, the membrane actuation may reinforce or counteract the boundary actuation, depending on the location of the ACL treatment. Finally, an energy analysis is developed to determine the proper control law that guarantees the stability of ACL shell treatments. Moreover, the energy analysis results in a simple rule predicting whether or not the membrane actuation reinforces the boundary actuation.

  16. From Bash to Z shell in 5 min

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Chances are you're spending a good amount of your time working on a shell. While Bash is the standard shell on Linux, some alternatives exist. I'll show you how to switch to one of them (Z shell) and what benefits come with it.

  17. Super-paramagnetic core-shell material with tunable magnetic behavior by regulating electron transfer efficiency and structure stability of the shell

    Directory of Open Access Journals (Sweden)

    Wenyan Zhang

    Full Text Available In this work, a spherical nano core-shell material was constructed by encapsulating Fe3O4 microsphere into conductive polymer-metal composite shell. The Fe3O4 microspheres were fabricated by assembling large amounts of Fe3O4 nano-crystals, which endowed the microspheres with super-paramagnetic property and high saturation magnetization. The polymer-metal composite shell was constructed by inserting Pt nano-particles (NPs into the conductive polymer polypyrrole (PPy. As size and dispersion of the Pt NPs has an important influence on their surface area and surface energy, it was effective to enlarge the interface area between PPy and Pt NPs, enhance the electron transfer efficiency of PPy/Pt composite shell, and reinforced the shell’s structural stability just by tuning the size and dispersion of Pt NPs. Moreover, core-shell structure of the materials made it convenient to investigate the PPy/Pt shell’s shielding effect on the Fe3O4 core’s magnetic response to external magnetic fields. It was found that the saturation magnetization of Fe3O4/PPy/Pt core-shell material could be reduced by 20.5% by regulating the conductivity of the PPy/Pt shell. Keywords: Super-paramagnetic, Conductivity, Magnetic shielding, Structural stability

  18. Shell Trumpets from Western Mexico

    Directory of Open Access Journals (Sweden)

    Robert Novella

    1991-11-01

    Full Text Available Marine shells have been used as musical instruments in almost all parts of the world (Izikowitz 1935, including Mesoamerica, where large univalves, also called conch shells in the literature, had a utilitarian function as trumpets. Their use is well documented in most cultural areas of Mesoamerica, as in Western Mexico, through their various occurrences in archaeological contexts and museums collections.

  19. Thick-shell nanocrystal quantum dots

    Science.gov (United States)

    Hollingsworth, Jennifer A [Los Alamos, NM; Chen, Yongfen [Eugene, OR; Klimov, Victor I [Los Alamos, NM; Htoon, Han [Los Alamos, NM; Vela, Javier [Los Alamos, NM

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  20. P-shell hyperon binding energies

    International Nuclear Information System (INIS)

    Koetsier, D.; Amos, K.

    1991-01-01

    A shell model for lambda hypernuclei has been used to determine the binding energy of the hyperon in nuclei throughout the p shell. Conventional (Cohen and Kurath) potential energies for nucleon-nucleon interactions were used with hyperon-nucleon interactions taken from Nijmegen one boson exchange potentials. The hyperon binding energies calculated from these potentials compare well with measured values. 7 refs., 2 figs

  1. SHELL DISEASES AND TOXINS REGULATED BY LAW

    Directory of Open Access Journals (Sweden)

    Natalija Topić Popović

    1999-06-01

    Full Text Available There is a long tradition of cultivating shells in Croatia, and the shell industry has a good perspective of further development. Since shells are delicate organisms that require special breeding conditions and climate, they are also subject to many diseases. Bonamiosis, haplospioridiosis, marteiliosis, microcytosis and perkinsosis are stated by the International Bureau for Epizootics as shell diseases that, in keeping with law, must be reported, and iridovirosis as a disease of a potential international importance. The same diseases are regulated by the Veterinary Law from 1997 as infectious diseases prevention of which is of an interest for the Republic of Croatia. Although, according to the law, it does not have to be prevented, in this article the disease Mytilicola is also described. According to the Health Department Statute from 1994, eatable part of shells are being tested for toxins of some marine dinoflagelates that can damage human health, and these are PSP (Paralytic Shellfish Poison, DSP (Diarrhoeic Shellfish Poison and NSP (Neuroparalytic Shellfish Poison.

  2. Vibrations of thin piezoelectric shallow shells: Two-dimensional ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two- dimensional eigenvalue problem. Keywords. Vibrations; piezoelectricity ...

  3. Microsoft Hyper-V PowerShell automation

    CERN Document Server

    Menon, Vinith

    2015-01-01

    This book is great for administrators who are new to automating Hyper-V administration tasks using PowerShell. If you are familiar with the PowerShell command line and have some experience with the Windows Server, this book is perfect for you.

  4. Acoustic coupling of two parallel shells in compressible fluid

    International Nuclear Information System (INIS)

    Gerges, S.N.Y.

    1982-01-01

    Modifications are done in the acoustic impedance for a vibrating shell, due to the pressure of another similar shell. The multi-analysis method of scattering is used. The results of the impedance in function of the shell radius, the wave length, the distance between the shell axis and its vibration models are presented. (E.G.) [pt

  5. Semiclassical shell structure and nuclear double-humped fission barriers

    Directory of Open Access Journals (Sweden)

    A. G. Magner

    2010-09-01

    Full Text Available We derived the semiclassical trace formulas for the level density as sums over periodic-orbit families and isolated orbits within the improved stationary phase method. Averaged level-density shell corrections and shell-structure energies are continuous through all symmetry-breaking (bifurcation points with the correct asymptotics of the standard stationary phase approach accounting for continuous symmetries. We found enhancement of the nuclear shell structure near bifurcations in the superdeformed region. Our semiclassical results for the averaged level densities with the gross-shell and more thin-shell structures and the energy shell corrections for critical deformations are in good agreement with the quantum calculations for several single-particle Hamiltonians, in particular for the potentials with a sharp spheroidal shape. Enhancement of the shell structure owing to bifurcations of the shortest 3-dimensional orbits from equatorial orbits is responsible for the second well of fission barrier in a superdeformation region.

  6. Plasma-column instabilities in a reversed-field pinch without a shell

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell.

  7. Plasma-column instabilities in a reversed-field pinch without a shell

    International Nuclear Information System (INIS)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell

  8. Clustering of 1p-shell nuclei in the framework of the shell model

    International Nuclear Information System (INIS)

    Kwasniewicz, E.

    1991-01-01

    The two- and three-fragment clustering of the 1p-shell nuclei has been studied in the framework of the shell model. The absolute probabilities of the required types of clustering in a given nucleus have been obtained by projecting its realistic shell-model wavefunction onto the suitable subspace of the orthonormal, completely antisymmetric two- or three-cluster states. With the aid of these data the selectivity in population of final states produced in multinucleon transfer reactions has been discussed. This problem has also been considered in the approach where the exchange of nucleons between clusters has been neglected. This has enabled to demonstrate the role of the complete antisymmetrization in predicting the intensities of states populated in multinucleon transfer reactions. The compact theory of the multinucleon one- and two-cluster spectroscopic amplitudes has been formulated. The examples of studying the nuclear structure and reactions with the aid of these spectroscopic amplitudes have been presented. (author)

  9. Shell-like structures advanced theories and applications

    CERN Document Server

    Eremeyev, Victor

    2017-01-01

    The book presents mathematical and mechanical aspects of the theory of plates and shells, applications in civil, aero-space and mechanical engineering, as well in other areas. The focus relates to the following problems: • comprehensive review of the most popular theories of plates and shells, • relations between three-dimensional theories and two-dimensional ones, • presentation of recently developed new refined plates and shells theories (for example, the micropolar theory or gradient-type theories), • modeling of coupled effects in shells and plates related to electromagnetic and temperature fields, phase transitions, diffusion, etc., • applications in modeling of non-classical objects like, for example, nanostructures, • presentation of actual numerical tools based on the finite element approach.

  10. Shell energy scenarios to 2050

    International Nuclear Information System (INIS)

    2008-01-01

    Shell developed two scenarios that describe alternative ways the energy future may develop. In the first scenario (Scramble) policymakers pay little attention to more efficient energy use until supplies are tight. Likewise, greenhouse gas emissions are not seriously addressed until there are major climate shocks. In the second scenario (Blueprints) growing local actions begin to address the challenges of economic development, energy security and environmental pollution. A price is applied to a critical mass of emissions giving a huge stimulus to the development of clean energy technologies, such as carbon dioxide capture and storage, and energy efficiency measures. The result is far lower carbon dioxide emissions. Both these scenarios can help Shell to test their strategy against a range of possible developments over the long-term. However, according to Shell, the Blueprints' outcomes offer the best hope for a sustainable future, whether or not they arise exactly in the way described. However, with the right combination of policy, technology and commitment from governments, industry and society globally, Shell believes it can be realized. But achieving the targets will not be easy, and time is short. Clear thinking, huge investment, and effective leadership are required

  11. Triggered Snap-Through of Bistable Shells

    Science.gov (United States)

    Cai, Yijie; Huang, Shicheng; Trase, Ian; Hu, Nan; Chen, Zi

    Elastic bistable shells are common structures in nature and engineering, such as the lobes of the Venus flytrap or the surface of a toy jumping poppers. Despite their ubiquity, the parameters that control the bistability of such structures are not well understood. In this study, we explore how the geometrical features of radially symmetric elastic shells affect the shape and potential energy of a shell's stable states, and how to tune certain parameters in order to generate a snap-through transition from a convex semi-stable state to concave stable state. We fabricated a series of elastic shells with varying geometric parameters out of silicone rubber and measured the resulting potential energy in the semi-stable state. Finite element simulations were also conducted in order to determine the deformation and stress in the shells during snap-through. It was found that the energy of the semi-stable state is controlled by only two geometric parameters and a dimensionless ratio. We also noted two distinct transitions during snap-through, one between monostability and semi-bistability (the state a popper toy is in before it snaps-through and jumps), and a second transition between semi-bistability and true bistability. This work shows that it is possible to use a set of simple parameters to tailor the energy landscape of an elastic shell in order to generate complex trigger motions for their potential use in smart applications. Z.C. acknowledge support from Society in Science-Branco Weiss Fellowship, administered by ETH Zurich.

  12. Systematic study of shell effect near drip-lines

    International Nuclear Information System (INIS)

    Adhikari, S.; Samanta, C.

    2004-01-01

    The variation of nuclear shell effects with nucleon numbers is evaluated using the modified Bethe–Weizsaecker mass formula (BWM) and the measured atomic masses. The shell effects at magic neutron numbers N=8, 20, 28, 50, 82 and 126 and magic proton numbers Z=8, 20, 28, 50 and 82 are found to vary rapidly approaching the drip-lines. The shell effect due to one magic number increases on approaching another magic number. Thus, shell effects are not always negligible near the drip-lines. (author)

  13. Inner-shell couplings in transiently formed superheavy quasimolecules

    Energy Technology Data Exchange (ETDEWEB)

    Verma, P [Kalindi College, University of Delhi, New Delhi 110008 (India); Mokler, P H [Max-Planck-Institut fuer Kernphysik, 69117 Heidelberg (Germany); Braeuning-Demian, A; Kozhuharov, C; Braeuning, H; Bosch, F; Hagmann, S; Liesen, D [GSI Helmholzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Anton, J; Fricke, B [Universitaet Kassel, 34109 Kassel (Germany); Stachura, Z [Institute for Nuclear Physics, Cracow PL 31342 (Poland); Wahab, M A, E-mail: p.verma.du@gmail.com [Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 (India)

    2011-06-15

    The inner-shell couplings for U{sup q+}-ions (73{<=}q{<=}91) moving moderately slow at {approx}69 MeV u{sup -1} and bombarding thin Au targets have been investigated. Having established the definite survival probability of incoming projectile K vacancies in these targets in an earlier publication, the transfer of these vacancies to the target K-shell due to inner-shell couplings has been studied. As the system is in the quasiadiabatic collision regime for the K-shell of collision partners, advanced SCF-DFS (self-consistent field-Dirac-Fock-Slater) multielectron level diagrams have been used for interpretation. Using a simple model, the L-K shell coupling interaction distance has been estimated and compared with level diagram calculations.

  14. Isospin invariant boson models for fp-shell nuclei

    International Nuclear Information System (INIS)

    Van Isacker, P.

    1994-01-01

    Isospin invariant boson models, IBM-3 and IBM-4, applicable in nuclei with neutrons and protons in the same valence shell, are reviewed. Some basic results related to these models are discussed: the mapping onto the shell model, the relation to Wigner's supermultiplet scheme, the boson-number and isospin dependence of parameters, etc. These results are examined for simple single-j shell situations (e.g. f 7/2 ) and their extension to the f p shell is investigated. Other extensions discussed here concern the treatment of odd-mass nuclei and the classification of particle-hole excitations in light nuclei. The possibility of a pseudo-SU(4) supermultiplet scheme in f p -shell nuclei is discussed. (author) 4 figs., 3 tabs., 23 refs

  15. Optical Bistability in Graded Core-Shell Granular Composites

    International Nuclear Information System (INIS)

    Wu Ya-Min; Chen Guo-Qing; Xue Si-Zhong; Zhu Zhuo-Wei; Ma Chao-Qun

    2012-01-01

    The intrinsic optical bistability (OB) of graded core-shell granular composites is investigated. The coated particles are made of cores with gradient dielectric function in c (r) = A(r/a) k and nonlinear shells. In view of the exponential distribution of the core dielectric constant, the potential functions of each region are obtained by solving the Maxwell equations, and the mathematical expressions of electric field in the shells and cores are determined. Numerical study reveals that the optical bistable threshold and the threshold width of the composite medium are dependent on the shell thickness, core dielectric exponent, and power function coefficient. The optical bistable width increases with the decreasing shell thickness and the power exponent and with the increasing power function coefficient

  16. Axisymmetric vibrations of thin shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kikuchi, Norio; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    The problem of free vibration of axisymmetric shells of revolution is important in connection with the design of pressure vessels, chemical equipment, aircrafts, structures and so on. In this study, the axisymmetrical vibration of a thin shell of revolution having a constant curvature in meridian direction was analyzed by thin shell theory. First, the Lagrangian during one period of the vibration of a shell of revolution was determined by the primary approximate theory of Love, and the vibration equations and boundary conditions were derived from its stopping condition. The vibration equations were strictly analyzed by using the series solution. The basic equations for the strain and strain energy of a shell were based on those of Novozhilov. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. The theory and the numerical calculation ore described. Especially in the frequency curves, the waving phenomena were observed frequently, which were not seen in non-axisymmetric vibration, accordingly also the vibration mode changed in complex state on the frequency curves of same order. The numerical calculation was carried out in the large computer center in Tohoku University. (Kako, I.)

  17. Microsoft Exchange Server PowerShell cookbook

    CERN Document Server

    Andersson, Jonas

    2015-01-01

    This book is for messaging professionals who want to build real-world scripts with Windows PowerShell 5 and the Exchange Management Shell. If you are a network or systems administrator responsible for managing and maintaining Exchange Server 2013, you will find this highly useful.

  18. Fast synthesis, formation mechanism, and control of shell thickness of CuS–polystyrene core–shell microspheres

    International Nuclear Information System (INIS)

    Zhao, Li-min; Shao, Xin; Yin, Yi-bin; Li, Wen-zhi

    2012-01-01

    Graphical abstract: Core–shell structure PSt/CuS were prepared using polystyrene which were modified by 3-methacryloxypropyltrimethoxysilane as template. The coating thickness of CuS can be controlled by the amount of 3-methacryloxypropyltrimethoxysilane and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. Highlights: ► Core–shell structure PSt/CuS were prepared using silanol-modified polystyrene microspheres as template. ► The coating thickness of core–shell structure PSt/CuS can be controlled by a simple method. ► The UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. -- Abstract: The silanol-modified polystyrene microspheres were prepared through dispersion polymerization. Then copper sulfide particles were grown on silanol-modified polystyrene through sonochemical deposition in an aqueous bath containing copper acetate and sulfide, released through the hydrolysis of thioacetamide. The resulting particles were continuous and uniform as characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared, thermogravimetric analysis and UV–vis absorption spectroscopy were used to characterize the structure and properties of core–shell particles. The results showed the coating thickness of CuS shell can be controlled by the amount of silanol and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS.

  19. Strontium and fluorine in tuatua shells

    International Nuclear Information System (INIS)

    Trompetter, W.J.; Coote, G.E.

    1993-01-01

    This report describes the research to date on the elemental distributions of strontium, calcium, and fluorine in a collection of 24 tuatua shells (courtesy of National Museum). Variations in elemental concentrations were measured in the shell cross-sections using a scanning proton microprobe (PIXE and PIGME). In this paper we report the findings to date, and present 2-D measurement scans as illustrative grey-scale pictures. Our results support the hypothesis that increased strontium concentrations are deposited in the shells during spawning, and that fluorine concentration is proportional to growth rate. (author). 15 refs.; 13 figs.; 1 appendix

  20. Insights from the Shell Proteome: Biomineralization to Adaptation.

    Science.gov (United States)

    Arivalagan, Jaison; Yarra, Tejaswi; Marie, Benjamin; Sleight, Victoria A; Duvernois-Berthet, Evelyne; Clark, Melody S; Marie, Arul; Berland, Sophie

    2017-01-01

    Bivalves have evolved a range of complex shell forming mechanisms that are reflected by their incredible diversity in shell mineralogy and microstructures. A suite of proteins exported to the shell matrix space plays a significant role in controlling these features, in addition to underpinning some of the physical properties of the shell itself. Although, there is a general consensus that a minimum basic protein tool kit is required for shell construction, to date, this remains undefined. In this study, the shell matrix proteins (SMPs) of four highly divergent bivalves (The Pacific oyster, Crassostrea gigas; the blue mussel, Mytilus edulis; the clam, Mya truncata, and the king scallop, Pecten maximus) were analyzed in an identical fashion using proteomics pipeline. This enabled us to identify the critical elements of a "basic tool kit" for calcification processes, which were conserved across the taxa irrespective of the shell morphology and arrangement of the crystal surfaces. In addition, protein domains controlling the crystal layers specific to aragonite and calcite were also identified. Intriguingly, a significant number of the identified SMPs contained domains related to immune functions. These were often are unique to each species implying their involvement not only in immunity, but also environmental adaptation. This suggests that the SMPs are selectively exported in a complex mix to endow the shell with both mechanical protection and biochemical defense. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  1. Effect of supercritical water shell on cavitation bubble dynamics

    International Nuclear Information System (INIS)

    Shao Wei-Hang; Chen Wei-Zhong

    2015-01-01

    Based on reported experimental data, a new model for single cavitation bubble dynamics is proposed considering a supercritical water (SCW) shell surrounding the bubble. Theoretical investigations show that the SCW shell apparently slows down the oscillation of the bubble and cools the gas temperature inside the collapsing bubble. Furthermore, the model is simplified to a Rayleigh–Plesset-like equation for a thin SCW shell. The dependence of the bubble dynamics on the thickness and density of the SCW shell is studied. The results show the bubble dynamics depends on the thickness but is insensitive to the density of the SCW shell. The thicker the SCW shell is, the smaller are the wall velocity and the gas temperature in the bubble. In the authors’ opinion, the SCW shell works as a buffering agent. In collapsing, it is compressed to absorb a good deal of the work transformed into the bubble internal energy during bubble collapse so that it weakens the bubble oscillations. (paper)

  2. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    The morphological evolution of bivalves is documented by a rich fossil record. It is believed that the shell shape and surface sculpture play an important role for the burrowing performance of endobenthic species. While detailed morphometric studies of bivalve shells have been done...... dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results...

  3. Scanning the parameter space of collapsing rotating thin shells

    Science.gov (United States)

    Rocha, Jorge V.; Santarelli, Raphael

    2018-06-01

    We present results of a comprehensive study of collapsing and bouncing thin shells with rotation, framing it in the context of the weak cosmic censorship conjecture. The analysis is based on a formalism developed specifically for higher odd dimensions that is able to describe the dynamics of collapsing rotating shells exactly. We analyse and classify a plethora of shell trajectories in asymptotically flat spacetimes. The parameters varied include the shell’s mass and angular momentum, its radial velocity at infinity, the (linear) equation-of-state parameter and the spacetime dimensionality. We find that plunges of rotating shells into black holes never produce naked singularities, as long as the matter shell obeys the weak energy condition, and so respects cosmic censorship. This applies to collapses of dust shells starting from rest or with a finite velocity at infinity. Not even shells with a negative isotropic pressure component (i.e. tension) lead to the formation of naked singularities, as long as the weak energy condition is satisfied. Endowing the shells with a positive isotropic pressure component allows for the existence of bouncing trajectories satisfying the dominant energy condition and fully contained outside rotating black holes. Otherwise any turning point occurs always inside the horizon. These results are based on strong numerical evidence from scans of numerous sections in the large parameter space available to these collapsing shells. The generalisation of the radial equation of motion to a polytropic equation-of-state for the matter shell is also included in an appendix.

  4. Coulomb ionization of inner shells by heavy charged particles

    International Nuclear Information System (INIS)

    Lapicki, G.

    1975-01-01

    The theory of inner-shell Coulomb ionization by heavy charged particles, of atomic number small compared to the target atomic number, is developed through the extension of work by Brandt and his coworkers for K shells to L shells. In slow collisions relative to the characteristic times of the inner shell electrons, the quantum-mechanical predictions in the plane-wave Born approximation (PWBA) can exceed experimental cross sections by orders of magnitude. The effects of the perturbation of the atom by and the Coulomb deflection of the particle during collisions are included in the theory. The perturbed atomic states amount to a binding of the inner-shell electrons to the moving particle in slow collisions, and to a polarization of the inner shells by the particle passing at large impact parameters during nonadiabatic collisions. These effects, not contained in the PWBA, are treated in the framework of the perturbed stationary state (PSS) theory for slow collisions and in terms of the harmonic oscillator model of Ashley, Brandt, and Ritchie for stopping powers in fast collisions. The effect of the Coulomb deflection of the particle in the field of the target nucleus on the cross sections is incorporated in the semiclassical approximation of Bang and Hansteen. Except for the lightest target atoms, the contribution of electron capture by the particles to inner-shell ionizations is shown to be negligible. The theory as developed earlier for the K shell, and here for L shells, agrees well with the vast body of experimental data on inner-shell Coulomb ionization by heavy charged particles

  5. Note on off-shell relations in nonlinear sigma model

    International Nuclear Information System (INIS)

    Chen, Gang; Du, Yi-Jian; Li, Shuyi; Liu, Hanqing

    2015-01-01

    In this note, we investigate relations between tree-level off-shell currents in nonlinear sigma model. Under Cayley parametrization, all odd-point currents vanish. We propose and prove a generalized U(1) identity for even-point currents. The off-shell U(1) identity given in http://dx.doi.org/10.1007/JHEP01(2014)061 is a special case of the generalized identity studied in this note. The on-shell limit of this identity is equivalent with the on-shell KK relation. Thus this relation provides the full off-shell correspondence of tree-level KK relation in nonlinear sigma model.

  6. Shell Scripting Expert Recipes for Linux, Bash and more

    CERN Document Server

    Parker, Steve

    2011-01-01

    A compendium of shell scripting recipes that can immediately be used, adjusted, and applied The shell is the primary way of communicating with the Unix and Linux systems, providing a direct way to program by automating simple-to-intermediate tasks. With this book, Linux expert Steve Parker shares a collection of shell scripting recipes that can be used as is or easily modified for a variety of environments or situations. The book covers shell programming, with a focus on Linux and the Bash shell; it provides credible, real-world relevance, as well as providing the flexible tools to get started

  7. Dispersion of axially symmetric waves in fluid-filled cylindrical shells

    DEFF Research Database (Denmark)

    Bao, X.L.; Überall, H.; Raju, P. K.

    2000-01-01

    Acoustic waves normally incident on an elastic cylindrical shell can cause the excitation of circumferential elastic waves on the shell. These shells may be empty and fluid immersed, or fluid filled in an ambient medium of air, or doubly fluid loaded inside and out. Circumferential waves...... on such shells have been investigated for the case of aluminum shells, and their phase-velocity dispersion curves have been obtained for double fluid loading [Bao, Raju, and Überall, J. Acoust. Soc. Am. 105, 2704 (1999)]. Similar results were obtained for empty or fluid-filled brass shells [Kumar, Acustica 27......, 317 (1972)]. We have extended the work of Kumar to the case of fluid-filled aluminum shells and steel shells imbedded in air. These cases demonstrate the existence of circumferential waves traveling in the filler fluid, exhibiting a certain simplicity of the dispersion curves of these waves...

  8. Integrable structure in discrete shell membrane theory.

    Science.gov (United States)

    Schief, W K

    2014-05-08

    We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory.

  9. Ancient shell industry at Bet Dwarka island

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.; Sundaresh; Patankar, V.

    for the manufacture of beads, bangles, etc. 12 . Shell species found at the sites include T. pyrum (cha nk), Chicoreus ramosus , Fasciolaria trapezium , Cypraea (cowries), Arabica arabica (cowries), Babylonia spirata , dentalium, mussel and Arca... muscles are attached. Average length of a shell can be up to 15 to 20 cm and width 10 ? 15 cm 8 . It provides a unique structure for the manufacture of several bangles from a single shell. The organ ism living inside is also edible...

  10. Isogeometric shell formulation based on a classical shell model

    KAUST Repository

    Niemi, Antti; Collier, Nathan; Dalcí n, Lisandro D.; Ghommem, Mehdi; Calo, Victor M.

    2012-01-01

    The authors future work is concerned with building an isogeometric finite element method for modelling nonlinear structural response of thin-walled shells undergoing large rigid-body motions. The aim is to use the model in a aeroelastic framework for the simulation of flapping wings.

  11. Coulomb energy of uniformly charged spheroidal shell systems.

    Science.gov (United States)

    Jadhao, Vikram; Yao, Zhenwei; Thomas, Creighton K; de la Cruz, Monica Olvera

    2015-03-01

    We provide exact expressions for the electrostatic energy of uniformly charged prolate and oblate spheroidal shells. We find that uniformly charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the formation of spheroidal structures over a sphere of equal area for high values of shell volume fractions.

  12. Vibrational analysis of submerged cylindrical shells based on elastic foundations

    International Nuclear Information System (INIS)

    Shah, A.G.; Naeem, M.N.

    2014-01-01

    In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

  13. Relativistic effects in atomic inner-shell transitions

    International Nuclear Information System (INIS)

    Chen, M.H.

    1982-01-01

    Theoretical calculations of atomic inner-shell transition rates based on independent-particle models are reviewed. Factors affecting inner-shell transition rates are examined, particularly the effects of relativity. 48 references, 5 figures

  14. Sequencing and analysis of the gastrula transcriptome of the brittle star Ophiocoma wendtii

    Directory of Open Access Journals (Sweden)

    Vaughn Roy

    2012-09-01

    Full Text Available Abstract Background The gastrula stage represents the point in development at which the three primary germ layers diverge. At this point the gene regulatory networks that specify the germ layers are established and the genes that define the differentiated states of the tissues have begun to be activated. These networks have been well-characterized in sea urchins, but not in other echinoderms. Embryos of the brittle star Ophiocoma wendtii share a number of developmental features with sea urchin embryos, including the ingression of mesenchyme cells that give rise to an embryonic skeleton. Notable differences are that no micromeres are formed during cleavage divisions and no pigment cells are formed during development to the pluteus larval stage. More subtle changes in timing of developmental events also occur. To explore the molecular basis for the similarities and differences between these two echinoderms, we have sequenced and characterized the gastrula transcriptome of O. wendtii. Methods Development of Ophiocoma wendtii embryos was characterized and RNA was isolated from the gastrula stage. A transcriptome data base was generated from this RNA and was analyzed using a variety of methods to identify transcripts expressed and to compare those transcripts to those expressed at the gastrula stage in other organisms. Results Using existing databases, we identified brittle star transcripts that correspond to 3,385 genes, including 1,863 genes shared with the sea urchin Strongylocentrotus purpuratus gastrula transcriptome. We characterized the functional classes of genes present in the transcriptome and compared them to those found in this sea urchin. We then examined those members of the germ-layer specific gene regulatory networks (GRNs of S. purpuratus that are expressed in the O. wendtii gastrula. Our results indicate that there is a shared ‘genetic toolkit’ central to the echinoderm gastrula, a key stage in embryonic development, though

  15. The status of experimental buckling investigations of shells

    International Nuclear Information System (INIS)

    Singer, J.

    1982-01-01

    The recent developments in shell buckling experiments are surveyed and related to a review of the progress in the seventies. Model fabrication, imperfection measurements, boundary conditions, nondestructive testing, combined loading, postbuckling behavior, composite shells and other aspects of shell buckling tests are discussed. The motivation for experiments and the conclusions drawn in the previous review are reassessed. (orig.)

  16. Majorana states in prismatic core-shell nanowires

    Science.gov (United States)

    Manolescu, Andrei; Sitek, Anna; Osca, Javier; Serra, Llorenç; Gudmundsson, Vidar; Stanescu, Tudor Dan

    2017-09-01

    We consider core-shell nanowires with conductive shell and insulating core and with polygonal cross section. We investigate the implications of this geometry on Majorana states expected in the presence of proximity-induced superconductivity and an external magnetic field. A typical prismatic nanowire has a hexagonal profile, but square and triangular shapes can also be obtained. The low-energy states are localized at the corners of the cross section, i.e., along the prism edges, and are separated by a gap from higher energy states localized on the sides. The corner localization depends on the details of the shell geometry, i.e., thickness, diameter, and sharpness of the corners. We study systematically the low-energy spectrum of prismatic shells using numerical methods and derive the topological phase diagram as a function of magnetic field and chemical potential for triangular, square, and hexagonal geometries. A strong corner localization enhances the stability of Majorana modes to various perturbations, including the orbital effect of the magnetic field, whereas a weaker localization favorizes orbital effects and reduces the critical magnetic field. The prismatic geometry allows the Majorana zero-energy modes to be accompanied by low-energy states, which we call pseudo Majorana, and which converge to real Majoranas in the limit of small shell thickness. We include the Rashba spin-orbit coupling in a phenomenological manner, assuming a radial electric field across the shell.

  17. A login shell interface for INFN-GRID

    Energy Technology Data Exchange (ETDEWEB)

    Pardi, S [INFN - Sezione di Napoli, Complesso di Monte S.Angelo - Via Cintia 80126 Napoli (Italy); Calloni, E; Rosa, R De; Garufi, F; Milano, L; Russo, G [Universita degli Studi di Napoli ' Federico M' , Dipartimento di Scienze Fisiche, Complesso di Monte S.Angelo - Via Cintia 80126 Napoli (Italy)], E-mail: silvio.pardi@na.infn.it

    2008-12-15

    The user interface is a crucial service to guarantee the Grid accessibility. The goal to achieve, is the implementation of an environment able to hide the grid complexity and offer a familiar interface to the final user. Currently many graphical interfaces have been proposed to simplify the grid access, but the GUI approach appears not very congenital to UNIX developers and users accustomed to work with command line interface. In 2004 the GridShell project proposed an extension of popular UNIX shells such as TCSH and BASH with features supporting Grid computing. Starting from the ideas included in GridShell, we propose IGSH (INFN-GRID SHELL) a new login shell for the INFN-GRID middleware, that interact with the Resource Broker services and integrates in a 'naturally way' the grid functionality with a familiar interface. The architecture of IGSH is very simple, it consist of a software layer on the top of the INFN-GRID middleware layer. When some operation is performed by the user, IGSH takes in charge to parse the syntax and translate it in the correspondents INFN-GRID commands according to some semantic rules specified in the next sections. The final user interacts with the underlying distributed infrastructure by using IGSH instead of his default login shell, with the sensation to work on a local machine.

  18. A login shell interface for INFN-GRID

    International Nuclear Information System (INIS)

    Pardi, S; Calloni, E; Rosa, R De; Garufi, F; Milano, L; Russo, G

    2008-01-01

    The user interface is a crucial service to guarantee the Grid accessibility. The goal to achieve, is the implementation of an environment able to hide the grid complexity and offer a familiar interface to the final user. Currently many graphical interfaces have been proposed to simplify the grid access, but the GUI approach appears not very congenital to UNIX developers and users accustomed to work with command line interface. In 2004 the GridShell project proposed an extension of popular UNIX shells such as TCSH and BASH with features supporting Grid computing. Starting from the ideas included in GridShell, we propose IGSH (INFN-GRID SHELL) a new login shell for the INFN-GRID middleware, that interact with the Resource Broker services and integrates in a 'naturally way' the grid functionality with a familiar interface. The architecture of IGSH is very simple, it consist of a software layer on the top of the INFN-GRID middleware layer. When some operation is performed by the user, IGSH takes in charge to parse the syntax and translate it in the correspondents INFN-GRID commands according to some semantic rules specified in the next sections. The final user interacts with the underlying distributed infrastructure by using IGSH instead of his default login shell, with the sensation to work on a local machine.

  19. Buckling strength of spherical shells under combined loads

    International Nuclear Information System (INIS)

    Nagashima, H.; Kokubo, K.; Takayanagi, M.; Hayasaka, Y.; Kume, T.; Nagata, T.

    1995-01-01

    Many studies on buckling of cylindrical shells have been conducted, and many buckling evaluation equations have been proposed for actual plant designs; however, buckling of spherical shells under combined horizontal and vertical loads cannot be evaluated due to insufficient data. There is a particular lack of buckling data for spherical shells under lateral loads. To establish a method for estimating the buckling strength of spherical shells, we investigate the interactions between horizontal and vertical (compressive tensile) loads by conducting buckling tests. Applying several combinations of these loads in tests and using computer linear analysis, we obtain interaction curves. This study reports on the buckling tests conducted using spherical shell 1120 mm in dia., 0.7 mm thick and 696 mm high, which are shaped individually by press-forming and finally joined together by four meridional welds, using a specially made jig. Initial imperfections before testing and local deformations after each loading increment during testing are measured with special measuring equipment, and the interaction curve of horizontal and vertical loads and effect of imperfection on the buckling strength of spherical shells are obtained. Nonlinear FEM programs are developed using an 8-node isoparametric shell element and a four-node quadrilateral element of C 0 type with reduced integration based upon a Mindlin-Reissner theory which includes transverse shear. Actual initial imperfections are generally in irregular patterns. Thus, there may be several definitions of the equivalent magnitudes of initial imperfections related to buckling loads. Equivalent magnitudes have no practical meaning unless they can be obtained easily not only for small structures such as test shells but also for large actual structures. In the present study, we define the equivalent magnitude of initial imperfections as the maximum local ruggedness measured radially from a circular temperature having a radius equal

  20. A novel Rapid Additive Manufacturing concept for architectural composite shell construction inspired by the shell formation in land snails.

    Science.gov (United States)

    Felbrich, Benjamin; Wulle, Frederik; Allgaier, Christoph; Menges, Achim; Verl, Alexander; Wurst, Karl-Heinz; Nebelsick, James

    2018-01-04

    State of the art rapid additive manufacturing (RAM), specifically Fused Filament Fabrication (FFF) has gained popularity among architects, engineers and designers for quick prototyping of technical devices, rapid production of small series and even construction scale fabrication of architectural elements. The spectrum of producible shapes and the resolution of detail, however, are determined and constrained by the layer-based nature of the fabrication process. These aspects significantly limit FFF-based approaches for the prefabrication and in-situ fabrication of freeform shells at the architectural scale. Snails exhibit a shell building process that suggests ways to overcome these limits. They produce a soft, pliable proteinaceous film - the periostracum - which later hardens and serves, among other functions, as a form-giving surface for an inner calcium carbonate layer. Snail shell formation behavior is interpreted from a technical point of view to extract potentially useful aspects for a biomimetic transfer. A RAM concept for continuous extrusion of thin free form composite shells inspired by the snail shell formation is presented. © 2018 IOP Publishing Ltd.

  1. Forced Vibration Analysis for a FGPM Cylindrical Shell

    Directory of Open Access Journals (Sweden)

    Hong-Liang Dai

    2013-01-01

    Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.

  2. Pemex to acquire interest in Shell Texas refinery

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that Petroleos Mexicanos and Shell Oil Co. have signed a memorandum of understanding to form a joint refining venture involving Shell's 225,000 b/d Deer Park, Tex., refinery. Under the agreement, Mexico's state owned oil company is to purchase a 50% interest in the refinery, and Shell is to sell Pemex unleaded gasoline on a long term basis. Under the venture, Shell and Pemex plan to add undisclosed conversion and upgrading units tailored to process heavy Mexican crude. The revamp will allow Pemex to place more than 100,000 b/d of Mayan heavy crude on the U.S. market. Mayan accounts for 70% of Mexico's crude oil exports. In turn, Shell will sell Pemex as much as 45,000 b/d of unleaded gasoline to help meet Mexico's rapidly growing demand

  3. Structural qualification of the multifunctional instrument tree for installation in double-shell and 100-series single-shell tanks

    International Nuclear Information System (INIS)

    Strohlow, J.P.

    1995-12-01

    This document provides the technical basis and methodology for qualifying the multifunctional instrument tree (MIT) structure for installation in double-shell and 100-series single-shell tanks. Structural qualification for MIT installations in specific tanks are also contained in this document

  4. Design criteria of launching rockets for burst aerial shells

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, T.; Takishita, Y.; Onda, T.; Shibamoto, H.; Hosaya, F. [Hosaya Kako Co. Ltd (Japan); Kubota, N. [Mitsubishi Electric Corporation (Japan)

    2000-04-01

    Rocket motors attached to large-sized aerial shells are proposed to compensate for the increase in the lifting charge in the mortar and the thickness of the shell wall. The proposal is the result of an evaluation of the performance of solid propellants to provide information useful in designing launch rockets for large-size shells. The propellants composed of ammonium perchlorate and hydroxy-terminated polybutadiene were used to evaluate the ballistic characteristics such as the relationship between propellant mass and trajectories of shells and launch rockets. In order to obtain an optimum rocket design, the evaluation also included a study of the velocity and height of the rocket motor and shell separation. A launch rocket with a large-sized shell (84.5 cm in diameter) was designed to verify the effectiveness of this class of launch system. 2 refs., 6 figs.

  5. Shell stabilization of super- and hyperheavy nuclei without magic gaps

    International Nuclear Information System (INIS)

    Bender, M.; Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.; Reinhard, P.G.; Oak Ridge National Lab., TN

    2001-05-01

    Quantum stabilization of superheavy elements is quantified in terms of the shell-correction energy. We compute the shell correction using self-consistent nuclear models: the non-relativistic Skyrme-Hartree-Fock approach and the relativistic mean-field model, for a number of parametrizations. All the forces applied predict a broad valley of shell stabilization around Z = 120 and N = 172-184. We also predict two broad regions of shell stabilization in hyperheavy elements with N ∼ 258 and N ∼ 308. Due to the large single-particle level density, shell corrections in the superheavy elements differ markedly from those in lighter nuclei. With increasing proton and neutron numbers, the regions of nuclei stabilized by shell effects become poorly localized in particle number, and the familiar pattern of shells separated by magic gaps is basically gone. (orig.)

  6. Electrochemical synthesis of CORE-shell magnetic nanowires

    KAUST Repository

    Ovejero, Jesús G.

    2015-04-16

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloys). Novel opportunities offered by such nanowires are discussed particularly the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare TM nanowires. These core-shell nanowires can be released from the template so, opening novel opportunities for biofunctionalization of individual nanowires.

  7. Core-shell architectures as nano-size transporters

    International Nuclear Information System (INIS)

    Adeli, M.; Zarnegar, Z.; Kabiri, R.; Salimi, F.; Dadkah, A.

    2006-01-01

    Core-shell architectures containing poly (ethylene imine) (PEI) as a core and poly (lactide) (PLA) as arms were prepared. PEI was used as macro initiator for ring opening polymerization of lactide. PEI-PLA core-shell architectures were able to encapsulate guest molecules. Size of the core-shell architectures was between 10- 100 nm, hence they can be considered as nano carriers to transport the guest molecules. Transport capacity of nano carriers depends on their nano-environments and type of self-assembly in solvent. In solid state nano carriers self-assemble as long structures with nano-size diameter or they form network structures. Aggregations type depends on the concentration of nano carriers in solution. Effect of the shell thickness and aggregation type on the release rate are also investigated

  8. Initial Single-Shell Tank Retrieval System mission analysis report

    International Nuclear Information System (INIS)

    Hertzel, J.S.

    1996-03-01

    This document provides the mission analysis for the Initial Single-Shell Tank Retrieval System task, which supports the Single-Shell Tank Waste Retrieval Program in its commitment to remove waste from single-shell tanks for treatment and final closure

  9. Synthesis of bimetallic Pt-Pd core-shell nanocrystals and their high electrocatalytic activity modulated by Pd shell thickness

    Science.gov (United States)

    Li, Yujing; Wang, Zhi Wei; Chiu, Chin-Yi; Ruan, Lingyan; Yang, Wenbing; Yang, Yang; Palmer, Richard E.; Huang, Yu

    2012-01-01

    Bimetallic Pt-Pd core-shell nanocrystals (NCs) are synthesized through a two-step process with controlled Pd thickness from sub-monolayer to multiple atomic layers. The oxygen reduction reaction (ORR) catalytic activity and methanol oxidation reactivity of the core-shell NCs for fuel cell applications in alkaline solution are systematically studied and compared based on different Pd thickness. It is found that the Pd shell helps to reduce the over-potential of ORR by up to 50mV when compared to commercial Pd black, while generating up to 3-fold higher kinetic current density. The carbon monoxide poisoning test shows that the bimetallic NCs are more resistant to the CO poisoning than Pt NCs and Pt black. It is also demonstrated that the bimetallic Pt-Pd core-shell NCs can enhance the current density of the methanol oxidation reaction, lowering the over-potential by 35 mV with respect to the Pt core NCs. Further investigation reveals that the Pd/Pt ratio of 1/3, which corresponds to nearly monolayer Pd deposition on Pt core NCs, gives the highest oxidation current density and lowest over-potential. This study shows for the first time the systematic investigation of effects of Pd atomic shells on Pt-Pd bimetallic nanocatalysts, providing valuable guidelines for designing high-performance catalysts for fuel cell applications.Bimetallic Pt-Pd core-shell nanocrystals (NCs) are synthesized through a two-step process with controlled Pd thickness from sub-monolayer to multiple atomic layers. The oxygen reduction reaction (ORR) catalytic activity and methanol oxidation reactivity of the core-shell NCs for fuel cell applications in alkaline solution are systematically studied and compared based on different Pd thickness. It is found that the Pd shell helps to reduce the over-potential of ORR by up to 50mV when compared to commercial Pd black, while generating up to 3-fold higher kinetic current density. The carbon monoxide poisoning test shows that the bimetallic NCs are more

  10. Dehydration of core/shell fruits

    OpenAIRE

    Liu, Y.; Yang, Xiaosong; Cao, Y.; Wang, Z.; Chen, B.; Zhang, Jian J.; Zhang, H.

    2015-01-01

    Dehydrated core/shell fruits, such as jujubes, raisins and plums, show very complex buckles and wrinkles on their exocarp. It is a challenging task to model such complicated patterns and their evolution in a virtual environment even for professional animators. This paper presents a unified physically-based approach to simulate the morphological transformation for the core/shell fruits in the dehydration process. A finite element method (FEM), which is based on the multiplicative decomposition...

  11. Study on reinforced lightweight coconut shell concrete beam behavior under flexure

    International Nuclear Information System (INIS)

    Gunasekaran, K.; Annadurai, R.; Kumar, P.S.

    2013-01-01

    Highlights: ► Use of coconut shell as aggregate in concrete. ► Behavior of coconut shell concrete under flexure. ► SEM images of cement, sand, coconut shell and coconut shell aggregate concrete. ► Coconut shell hollow blocks and precast slabs are used in practice. - Abstract: Coconut shell has been used as coarse aggregate in the production of concrete. The flexural behavior of reinforced concrete beam made with coconut shell is analyzed and compared with the normal control concrete. Twelve beams, six with coconut shell concrete and six with normal control concrete, were fabricated and tested. This study includes the moment capacity, deflection, cracking, ductility, corresponding strains in both compression and tension, and end rotation. It was found that the flexural behavior of coconut shell concrete is comparable to that of other lightweight concretes. The results of concrete compression strain and steel tension strain showed that coconut shell concrete is able to achieve its full strain capacity under flexural loadings. Under serviceability condition, deflection and cracking characteristics of coconut shell concrete are comparable with control concrete. However, the failure zones of coconut shell concrete were larger than for control concrete beams. The end rotations of the coconut shell concrete beams just prior to failure values are comparable to other lightweight concretes. Coconut shell concrete was used to produce hollow blocks and precast slab in 2007 and they are being subjected to some practical loading till today without any problems such as deflection, bending, cracks, and damages for the past five years

  12. Læren fra Shell

    DEFF Research Database (Denmark)

    Ørding Olsen, Anders

    2017-01-01

    Hvad kan afsløringerne om Shells mere end 25 år gamle viden om klimaforandringer lære virksomheder om disruption og strategi? Først og fremmest at undgå at se disruption som en mulig trussel, men i stedet som en fremtidig realitet og chance for vækst......Hvad kan afsløringerne om Shells mere end 25 år gamle viden om klimaforandringer lære virksomheder om disruption og strategi? Først og fremmest at undgå at se disruption som en mulig trussel, men i stedet som en fremtidig realitet og chance for vækst...

  13. Graded core/shell semiconductor nanorods and nanorod barcodes

    Science.gov (United States)

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2010-12-14

    Graded core/shell semiconductor nanorods and shaped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  14. Zero-point energy of N perfectly conducting concentric cylindrical shells

    International Nuclear Information System (INIS)

    Tatur, K.; Woods, L.M.

    2008-01-01

    The zero-point (Casimir) energy of N perfectly conducting, infinitely long, concentric cylindrical shells is calculated utilizing the mode summation technique. The obtained convergent expression is studied as a function of size, curvature and number of shells. Limiting cases, such as infinitely close shells or infinite radius shells are also investigated

  15. The influence of shell thickness of Au@TiO2 core-shell nanoparticles on the plasmonic enhancement effect in dye-sensitized solar cells.

    Science.gov (United States)

    Liu, Wei-Liang; Lin, Fan-Cheng; Yang, Yu-Chen; Huang, Chen-Hsien; Gwo, Shangjr; Huang, Michael H; Huang, Jer-Shing

    2013-09-07

    Plasmonic core-shell nanoparticles (PCSNPs) can function as nanoantennas and improve the efficiency of dye-sensitized solar cells (DSSCs). To achieve maximum enhancement, the morphology of PCSNPs needs to be optimized. Here we precisely control the morphology of Au@TiO2 PCSNPs and systematically study its influence on the plasmonic enhancement effect. The enhancement mechanism was found to vary with the thickness of the TiO2 shell. PCSNPs with a thinner shell mainly enhance the current, whereas particles with a thicker shell improve the voltage. While pronounced plasmonic enhancement was found in the near infrared regime, wavelength-independent enhancement in the visible range was observed and attributed to the plasmonic heating effect. Emission lifetime measurement confirms that N719 molecules neighboring nanoparticles with TiO2 shells exhibit a longer lifetime than those in contact with metal cores. Overall, PCSNPs with a 5 nm shell give the highest efficiency enhancement of 23%. Our work provides a new synthesis route for well-controlled Au@TiO2 core-shell nanoparticles and gains insight into the plasmonic enhancement in DSSCs.

  16. Testing refined shell-model interactions in the sd shell: Coulomb excitation of Na26

    CERN Document Server

    Siebeck, B; Blazhev, A; Reiter, P; Altenkirch, R; Bauer, C; Butler, P A; De Witte, H; Elseviers, J; Gaffney, L P; Hess, H; Huyse, M; Kröll, T; Lutter, R; Pakarinen, J; Pietralla, N; Radeck, F; Scheck, M; Schneiders, D; Sotty, C; Van Duppen, P; Vermeulen, M; Voulot, D; Warr, N; Wenander, F

    2015-01-01

    Background: Shell-model calculations crucially depend on the residual interaction used to approximate the nucleon-nucleon interaction. Recent improvements to the empirical universal sd interaction (USD) describing nuclei within the sd shell yielded two new interactions—USDA and USDB—causing changes in the theoretical description of these nuclei. Purpose: Transition matrix elements between excited states provide an excellent probe to examine the underlying shell structure. These observables provide a stringent test for the newly derived interactions. The nucleus Na26 with 7 valence neutrons and 3 valence protons outside the doubly-magic 16O core is used as a test case. Method: A radioactive beam experiment with Na26 (T1/2=1,07s) was performed at the REX-ISOLDE facility (CERN) using Coulomb excitation at safe energies below the Coulomb barrier. Scattered particles were detected with an annular Si detector in coincidence with γ rays observed by the segmented MINIBALL array. Coulomb excitation cross sections...

  17. Shell-side single-phase flows and heat transfer in shell-and-tube heat exchangers, 4

    International Nuclear Information System (INIS)

    Matsushita, Hitoshi; Nakayama, Wataru; Yanagida, Takehiko; Kudo, Akio.

    1987-01-01

    Refering to the results of our previous works, a procedure for estimating the distribution of heat flux in shell-and-tube heat exchangers is proposed. The steam generator used in a high temperature reactor plant is taken up as the subject of analysis. Particular attention is paid to critical conditions for burnout and the strength of material in high temperature conditions. It is found that the distribution of heat transfer coefficient on the shell-side is crucial to the occurrence of burnout in the tubes. The use of a relatively large inlet nozzle (the ratio of its diameter to the shell is roughly half) is recommended. A low level of thermal stress on heat transfer tubes can be realized by the adoption of a relatively thin 2.25 Cr-1 Mo Steel tube wall of 1.24 mm thickness. (author)

  18. Shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowires

    Science.gov (United States)

    Wen, Feng; Dillen, David C.; Kim, Kyounghwan; Tutuc, Emanuel

    2017-06-01

    We investigate the shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowire heterostructures grown using a combination of a vapor-liquid-solid (VLS) growth mechanism for the core, followed by in-situ epitaxial shell growth using ultra-high vacuum chemical vapor deposition. Cross-sectional transmission electron microscopy reveals that the VLS growth yields cylindrical Ge, and Si nanowire cores grown along the ⟨111⟩, and ⟨110⟩ or ⟨112⟩ directions, respectively. A hexagonal cross-sectional morphology is observed for Ge-SixGe1-x core-shell nanowires terminated by six {112} facets. Two distinct morphologies are observed for Si-SixGe1-x core-shell nanowires that are either terminated by four {111} and two {100} planes associated with the ⟨110⟩ growth direction or four {113} and two {111} planes associated with the ⟨112⟩ growth direction. We show that the Raman spectra of Si- SixGe1-x are correlated with the shell morphology thanks to epitaxial growth-induced strain, with the core Si-Si mode showing a larger red shift in ⟨112⟩ core-shell nanowires compared to their ⟨110⟩ counterparts. We compare the Si-Si Raman mode value with calculations based on a continuum elasticity model coupled with the lattice dynamic theory.

  19. Immediate catalytic upgrading of soybean shell bio-oil

    International Nuclear Information System (INIS)

    Bertero, Melisa; Sedran, Ulises

    2016-01-01

    The pyrolysis of soybean shell and the immediate catalytic upgrading of the bio-oil over an equilibrium FCC catalyst was studied in order to define its potential as a source for fuels and chemicals. The experiments of pyrolysis and immediate catalytic upgrading were performed at 550 °C during 7 min with different catalysts to oil relationships in an integrated fixed bed pyrolysis-conversion reactor. The results were compared under the same conditions against those from pine sawdust, which is a biomass source commonly used for the production of bio-oil. In the pyrolysis the pine sawdust produced more liquids (61.4%wt.) than the soybean shell (54.7%wt.). When the catalyst was presented, the yield of hydrocarbons increased, particularly in the case of soybean shell, which was four time higher than in the pyrolysis. The bio-oil from soybean shell produced less coke (between 3.1 and 4.3%wt.) in its immediate catalytic upgrading than that from pine sawdust (between 5 and 5.8%wt.), due to its lower content of phenolic and other high molecular weight compounds (three and five times less, respectively). Moreover, soybean shell showed a higher selectivity to hydrocarbons in the gasoline range, with more olefins and less aromatic than pine sawdust. - Highlights: • Soybean shell is a possible source of fuels with benefits as compared to pine sawdust. • Bio-oils upgraded over FCC catalyst in an integrated pyrolysis-conversion reactor. • Pine sawdust bio-oil had more phenols than soybean shell bio-oil. • Soybean shell bio-oil produced more hydrocarbons in gasoline range and less coke.

  20. Waves on fluid-loaded shells and their resonance frequency spectrum

    DEFF Research Database (Denmark)

    Bao, X.L.; Uberall, H.; Raju, P.K.

    2005-01-01

    , or axially propagating waves both in the shell material, and in the fluid loading. Previous results by Bao et al. (J. Acoust. Soc. Am. 105 (1999) 2704) were obtained for the circumferential-wave dispersion curves on doubly loaded aluminum shells; the present study extends this to fluid-filled shells in air......Technical requirements for elastic (metal) cylindrical shells include the knowledge of their natural frequency spectrum. These shells may be empty and fluid-immersed, or fluid-filled in an ambient medium of air, or doubly fluid-loaded inside and out. They may support circumferential waves....... For practical applications, steel shells are most important and we have here obtained corresponding results for these. To find the natural frequencies of cylindrical shells, one may invoke the principle of phase matching where resonating standing waves are formed around the circumference, or in the axial...

  1. POPULATION PHARMACOKINETICS OF ENROFLOXACIN AND ITS METABOLITE CIPROFLOXACIN IN THE GREEN SEA URCHIN (STRONGYLOCENTROTUS DROEBACHIENSIS) FOLLOWING INTRACOELOMIC AND IMMERSION ADMINISTRATION.

    Science.gov (United States)

    Phillips, Brianne E; Harms, Craig A; Lewbart, Gregory A; Lahner, Lesanna L; Haulena, Martin; Rosenberg, Justin F; Papich, Mark G

    2016-03-01

    Sea urchin mass mortality events have been attributed to both infectious and noninfectious etiologies. Bacteria, including Vibrio spp. and Pseudoalteromonas spp., have been isolated during specific mortality events. Aquarium collection sea urchins are also subject to bacterial infections and could benefit from antimicrobial treatment, but pharmacokinetic studies have been lacking for this invertebrate group until recently. This study evaluated the pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin in the green sea urchin (Strongylocentrotus droebachiensis) after intracoelomic injection and medicated bath immersion administration. The utility of a population pharmacokinetic method using nonlinear mixed effects modeling (NLME) was also evaluated. Thirty sea urchins were assigned to either the injection or immersion group. Twelve study animals and three untreated controls were utilized for each administration method: enrofloxacin 10 mg/kg intracoelomic injection or a 6-hr enrofloxacin 10 mg/L immersion. Each animal was sampled four times from 0 to 120 hr. Water samples were collected during immersion treatment and posttreatment time points in both groups. Hemolymph and water sample drug concentrations were analyzed using high-performance liquid chromatography, and pharmacokinetic parameters were determined using an NLME population pharmacokinetic method. Enrofloxacin concentrations were fit to a two-compartment model with first-order input for the intracoelomic injection group. The enrofloxacin elimination half-life (t½), peak hemolymph concentration (CMAX), and area under the curve (AUC) were 38.82 hr, 90.92 μg/ml, and 1,199 hr·μg/ml, respectively. Enrofloxacin was modeled to a one-compartment model with first-order input for the immersion treatment. The enrofloxacin t½, CMAX, and AUC were 33.46 hr, 0.48 μg/ml, and 32.88 hr·μg/ml, respectively. Ciprofloxacin was detected in trace concentrations in all hemolymph samples, indicating

  2. DNA nanoparticles with core-shell morphology.

    Science.gov (United States)

    Chandran, Preethi L; Dimitriadis, Emilios K; Lisziewicz, Julianna; Speransky, Vlad; Horkay, Ferenc

    2014-10-14

    Mannobiose-modified polyethylenimines (PEI) are used in gene therapy to generate nanoparticles of DNA that can be targeted to the antigen-presenting cells of the immune system. We report that the sugar modification alters the DNA organization within the nanoparticles from homogenous to shell-like packing. The depth-dependent packing of DNA within the nanoparticles was probed using AFM nano-indentation. Unmodified PEI-DNA nanoparticles display linear elastic properties and depth-independent mechanics, characteristic of homogenous materials. Mannobiose-modified nanoparticles, however, showed distinct force regimes that were dependent on indentation depth, with 'buckling'-like response that is reproducible and not due to particle failure. By comparison with theoretical studies of spherical shell mechanics, the structure of mannobiosylated particles was deduced to be a thin shell with wall thickness in the order of few nanometers, and a fluid-filled core. The shell-core structure is also consistent with observations of nanoparticle denting in altered solution conditions, with measurements of nanoparticle water content from AFM images, and with images of DNA distribution in Transmission Electron Microscopy.

  3. FABRICATION OF GAS-FILLED TUNGSTEN-COATED GLASS SHELLS

    International Nuclear Information System (INIS)

    NIKROO, A; BAUGH, W; STEINMAN, D.A.

    2003-09-01

    OAK-B135 Deuterium (D 2 ) filled glass shells coated with a high Z element are needed for high energy density (HED) experiments by researchers at Los Alamos National Laboratory. They report here on our initial attempt to produce such shells. Glass shells made using the drop tower technique were coated with gold, palladium or tungsten, or a mixture of two of these elements. It was found that gold and palladium coatings did not stick well to the glass and resulted in poor or delaminated films. Tungsten coatings resulted in films suitable for these targets. Bouncing of shells during coating resulted in uniform tungsten coatings, but the surface of such coatings were filled with small nodules. Proper agitation of shells using a tapping technique resulted in smooth films with minimal particulate contamination. For coating rates of ∼ 0.15 (micro)m/hr coatings with ∼ 2 nm RMS surface finish could be deposited. The surface roughness of coatings at higher rates, 0.7 (micro)m/hr, was considerably worse (∼ 100 nm RMS). The columnar structure of the coatings allowed permeation filling of the tungsten coated glass shells with deuterium at 300 C

  4. On-shell diagrams for N=8 supergravity amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Heslop, Paul; Lipstein, Arthur E. [Department of Mathematical Sciences, Durham University,Lower Mountjoy, Stockton Road, Durham, DH1 3LE (United Kingdom)

    2016-06-10

    We define recursion relations for N=8 supergravity amplitudes using a generalization of the on-shell diagrams developed for planar N=4 super-Yang-Mills. Although the recursion relations generically give rise to non-planar on-shell diagrams, we show that at tree-level the recursion can be chosen to yield only planar diagrams, the same diagrams occurring in the planar N=4 theory. This implies non-trivial identities for non-planar diagrams as well as interesting relations between the N=4 and N=8 theories. We show that the on-shell diagrams of N=8 supergravity obey equivalence relations analogous to those of N=4 super-Yang-Mills, and we develop a systematic algorithm for reading off Grassmannian integral formulae directly from the on-shell diagrams. We also show that the 1-loop 4-point amplitude of N=8 supergravity can be obtained from on-shell diagrams.

  5. Theory of hydrogen shell flashes on accreting white dwarfs. II. The stable shell burning and the recurrence period of shell flashes

    International Nuclear Information System (INIS)

    Fujimoto, M.Y.

    1982-01-01

    By means of analytical solutions of the envelope, thermal properties of hydrogen shell burning on accreting white dwarfs are studied and a general picture for their progress is presented which is described by two parameters, the accretion rate and the mass of the white dwarf. On a white dwarf, the thermal behavior of gas in the burning shell depends on the configuration of the envelope, which gives birth to two distinct types of stable configurations in thermal equilibrium, a high and a low state. In the high state, the nuclear shell burning makes up for the energy loss from the surface. There exists the lower limit to the envelope mass for this state. The nuclear burning rate lies in a narrow range of about a factor of 2.5, irrespective of the mass of the white dwarf, while the range itself varies greatly with the latter. In the low state, the nuclear burning is extinct, and yet the compressional heating by accreted gas balances with the cooling through the diffusion of heat. Therefore, the structure depends on the accretion rate. Thermal instability of nuclear burning sets the upper limit to the envelope mass of this state

  6. Many-body forces in nuclear shell-model

    International Nuclear Information System (INIS)

    Rath, P.K.

    1985-01-01

    In the microscopic derivation of the effective Hamiltonian for the nuclear shell model many-body forces between the valence nucleons occur. These many-body forces can be discriminated in ''real'' many-body forces, which can be related to mesonic and internal degrees of freedom of the nucleons, and ''effective'' many-body forces, which arise by the confinement of the nucleonic Hilbert space to the finite-dimension shell-model space. In the present thesis the influences of such three-body forces on the spectra of sd-shell nuclei are studied. For this the two common techniques for shell-model calculations (Oak Ridge-Rochester and Glasgow representation) are extended in such way that a general three-body term in the Hamiltonian can be regarded. The studies show that the repulsive contributions of the considered three-nucleon forces become more important with increasing number of valence nucleons. By this the particle-number dependence of empirical two-nucleon forces can be qualitatively explained. A special kind of effective many-body force occurs in the folded diagram expansion of the energy-dependent effective Hamiltonian for the shell model. Thereby it is shown that the contributions of the folded diagrams with three nucleons are just as important as those with two nucleons. Thus it is to be suspected that the folded diagram expansion contains many-particle terms with arbitrary particle number. The present studies however show that four nucleon effects are neglegible so that the folded diagram expansion can be confined to two- and three-particle terms. In shell-model calculations which extend over several main shells the influences of the spurious center-of-mass motion must be regarded. A procedure is discussed by which these spurious degrees of freedom can be exactly separated. (orig.) [de

  7. Windows PowerShell Cookbook The Complete Guide to Scripting Microsoft's New Command Shell

    CERN Document Server

    Holmes, Lee

    2010-01-01

    Do you know how to use Windows PowerShell to navigate the filesystem and manage files and folders? Or how to retrieve a web page? This introduction to the PowerShell language and scripting environment provides more than 430 task-oriented recipes to help you solve the most complex and pressing problems, and includes more than 100 tried-and-tested scripts that intermediate to advanced system administrators can copy and use immediately. You'll find hands-on tutorials on fundamentals, common tasks, and administrative jobs that you can apply whether you're on a client or server version of Windows

  8. Driven self-assembly of hard nanoplates on soft elastic shells

    International Nuclear Information System (INIS)

    Zhang Yao-Yang; Hua Yun-Feng; Deng Zhen-Yu

    2015-01-01

    The driven self-assembly behaviors of hard nanoplates on soft elastic shells are investigated by using molecular dynamics (MD) simulation method, and the driven self-assembly structures of adsorbed hard nanoplates depend on the shape of hard nanoplates and the bending energy of soft elastic shells. Three main structures for adsorbed hard nanoplates, including the ordered aggregation structures of hard nanoplates for elastic shells with a moderate bending energy, the collapsed structures for elastic shells with a low bending energy, and the disordered aggregation structures for hard shells, are observed. The self-assembly process of adsorbed hard nanoplates is driven by the surface tension of the elastic shell, and the shape of driven self-assembly structures is determined on the basis of the minimization of the second moment of mass distribution. Meanwhile, the deformations of elastic shells can be controlled by the number of adsorbed rods as well as the length of adsorbed rods. This investigation can help us understand the complexity of the driven self-assembly of hard nanoplates on elastic shells. (paper)

  9. Axial strain in GaAs/InAs core-shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Biermanns, Andreas; Pietsch, Ullrich [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany); Rieger, Torsten; Gruetzmacher, Detlev; Ion Lepsa, Mihail [Peter Gruenberg Institute (PGI-9), Forschungszentrum, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technology, 52425 Juelich (Germany); Bussone, Genziana [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany); ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex (France)

    2013-01-28

    We study the axial strain relaxation in GaAs/InAs core-shell nanowire heterostructures grown by molecular beam epitaxy. Besides a gradual strain relaxation of the shell material, we find a significant strain in the GaAs core, increasing with shell thickness. This strain is explained by a saturation of the dislocation density at the core-shell interface. Independent measurements of core and shell lattice parameters by x-ray diffraction reveal a relaxation of 93% in a 35 nm thick InAs shell surrounding cores of 80 nm diameter. The compressive strain of -0.5% compared to bulk InAs is accompanied by a tensile strain up to 0.9% in the GaAs core.

  10. Hydration shells exchange charge with their protein

    DEFF Research Database (Denmark)

    Abitan, Haim; Lindgård, Per-Anker; Nielsen, Bjørn Gilbert

    2010-01-01

    . In our experiments, the amplitude of an ultrasonic pressure wave is gradually increased (0–20 atm) while we simultaneously measure the Raman spectra from the hydrated protein (β-lactoglobulin and lysozyme). We detected two types of spectral changes: first, up to 70% increase in the intensity......Investigation of the interaction between a protein and its hydration shells is an experimental and theoretical challenge. Here, we used ultrasonic pressure waves in aqueous solutions of a protein to explore the conformational states of the protein and its interaction with its hydration shells...... the presence of an ultrasonic pressure, a protein and its hydration shells are in thermodynamic and charge equilibrium, i.e. a protein and its hydration shells exchange charges. The ultrasonic wave disrupts these equilibria which are regained within 30–45 min after the ultrasonic pressure is shut off....

  11. Cask for concrete shells transportation

    International Nuclear Information System (INIS)

    Labergri, F.

    2001-01-01

    Nowadays, nuclear plant radioactive waste are conditioned in situ into concrete shells. Most of them enter in the industrial waste category defined by the regulations of radioactive material transportation. However, the content of a few ones exceeds the limits set for low specific activity substances. Thus, these shells must be transported into type B packagings. To this end, Robatel has undertaken, for EDF (Electricite de France), the development of a container, named ROBATEL TM R68, for further licensing. The particularity of this packaging is that the lid must have a wide opening to allow the usual handling operations of the concrete shells. This leads to a non-conventional conception, and makes the package more vulnerable to drop test solicitations. In order to define a minimal drop test program on a reduced scale model, we use a simple method to find the most damageable drop angle. (author)

  12. Characterization of Physic nut (Jatropha curcas L.) shells

    International Nuclear Information System (INIS)

    Wever, Diego-Armando Z.; Heeres, H.J.; Broekhuis, Antonius A.

    2012-01-01

    The characterization of Physic nut shells was done using the wet chemical analysis of wood components. The obtained fractions were analyzed using IR, NMR, GPC, ICP and MALDI-TOF mass spectroscopy. TGA was used to determine the fixed carbon (+ash) and water content of the shells. The results of wet chemical analysis of wood components offered a clear procedure to isolate the main components in Physic nut shells (a). The fractions obtained were: polar extract (b), non-polar extract (c), Acid Insoluble Lignin (d), Holocellulose (e), α-Cellulose (f). The total Lignin content present in the shells equaled 48.84%. IR and NMR spectroscopy demonstrated that the non-polar extract is Lignin, which corresponds to the extractable Lignin (1.24%) in the Physic nut shells and the Acid Insoluble Lignin was 47.60%. Elemental analysis showed no Sulfur present in the investigated materials. Furthermore both 1 H and 13 C NMR of the non-polar extract showed the presence of aliphatic hydrocarbon chains. The α-Cellulose content (22.29%) and the Hemicelluloses content (23.84%) were in line with that of agricultural residues. The water content and the fixed carbon content (+ash [2.8%]) equal 5–6% and 35.6%, respectively. GPC showed that the polydispersity of the non-polar extract (3.6) lies between Alcell Lignin and Kraft Lignin. The polar extract contains a variety of metals, with especially a high amount of the alkali metals K and Na. The extraction with water is proposed to generate a fertilizer fraction and may be applied to reduce potential sintering issues during eventual combustion or gasification of the shells. -- Highlights: ► Physic nut shell is a potential source of value added chemicals due to its high lignin content (48.8 wt%). ► Lignin extracted from Jatropha curcas L. shells is rich in aliphatic linkages. ► Water extraction of the shells yields a potential fertilizer fraction rich in alkali metals and phosphorous. ► Pre-extraction is recommended to eliminate

  13. Nonlinear thermo-optical properties of two-layered spherical system of gold nanoparticle core and water vapor shell during initial stage of shell expansion

    Directory of Open Access Journals (Sweden)

    Astafyeva Liudmila

    2011-01-01

    Full Text Available Abstract Nonlinear thermo-optical properties of two-layered spherical system of gold nanoparticle core and water vapor shell, created under laser heating of nanoparticle in water, were theoretically investigated. Vapor shell expansion leads to decreasing up to one to two orders of magnitude in comparison with initial values of scattering and extinction of the radiation with wavelengths 532 and 633 nm by system while shell radius is increased up to value of about two radii of nanoparticle. Subsequent increasing of shell radius more than two radii of nanoparticle leads to rise of scattering and extinction properties of system over initial values. The significant decrease of radiation scattering and extinction by system of nanoparticle-vapor shell can be used for experimental detection of the energy threshold of vapor shell formation and investigation of the first stages of its expansion. PACS: 42.62.BE. 78.67. BF

  14. Study on reinforced lightweight coconut shell concrete beam behavior under shear

    International Nuclear Information System (INIS)

    Gunasekaran, K.; Annadurai, R.; Kumar, P.S.

    2013-01-01

    Highlights: • Coconut shell used as aggregate in concrete production. • Coconut shell concrete beam behavior studied under shear. • Coconut shell concrete beam behavior are compared with control concrete beams. - Abstract: Lightweight concrete has been produced using crushed coconut shell as coarse aggregate. The shear behavior of reinforced concrete beam made with coconut shell is analyzed and compared with the normal control concrete. Eight beams, four with coconut shell concrete and four with normal control concrete were fabricated and tested. Study includes the structural shear behavior, shear capacity, cracking behavior, deflection behavior, ductility, strains in concrete and in reinforcement. It was observed that the shear behavior of coconut shell concrete is comparable to that of other lightweight concretes. The results of concrete compression strain and steel tension strain showed that coconut shell concrete is able to achieve its full strain capacity under shear loadings. However, the failure zones of coconut shell concrete were larger than for control concrete beams

  15. Strontium clusters: electronic and geometry shell effects

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2008-01-01

    charged strontium clusters consisting of up to 14 atoms, average bonding distances, electronic shell closures, binding energies per atom, and spectra of the density of electronic states (DOS). It is demonstrated that the size-evolution of structural and electronic properties of strontium clusters...... is governed by an interplay of the electronic and geometry shell closures. Influence of the electronic shell effects on structural rearrangements can lead to violation of the icosahedral growth motif of strontium clusters. It is shown that the excessive charge essentially affects the optimized geometry...

  16. Gross shell structure of moments of inertia

    International Nuclear Information System (INIS)

    Deleplanque, M.A.; Frauendorf, S.; Pashkevich, V.V.; Chu, S.Y.; Unzhakova, A.

    2002-01-01

    Average yrast moments of inertia at high spins, where the pairing correlations are expected to be largely absent, were found to deviate from the rigid-body values. This indicates that shell effects contribute to the moment of inertia. We discuss the gross dependence of moments of inertia and shell energies on the neutron number in terms of the semiclassical periodic orbit theory. We show that the ground-state shell energies, nuclear deformations and deviations from rigid-body moments of inertia are all due to the same periodic orbits

  17. FABRICATION AND PROPERTIES OVERCOATED RESORCINOL-FORMALDEHYDE SHELLS FOR OMEGA EXPERIMENTS

    International Nuclear Information System (INIS)

    NIKROO, A; CZECHOWICZ, D; PAGUIO, R; GREENWOOD, A.L; TAKAGI, M.

    2003-09-01

    OAK-B135 New high gain designs for direct drive ignition on NIF require foam shells. Scaled down versions of these designs are needed for near term experiments on the OMEGA laser facility at the Laboratory Laser Energetics (LLE). These shells need to be about 1 mm in diameter and 50-100 (micro)m wall thickness and densities of 100-250 mg/cc. In addition, a full density permeation seal needs to be deposited for retention of the fill gas at room temperature or the ice at cryogenic temperatures. They have fabricated such shells using Resorcinol-formaldehyde (R/F) as the selected foam material due to its transparency in the optical region. Extensive characterization of the wall uniformity of these shells has been performed. The foam shells have ∼ 5%-6% non-concentricities on the average. A full density permeation seal has been deposited on the R/F shells using two different techniques. In the first technique R/F shells are coated directly with plasma polymer to thicknesses of 3-4 (micro)m. In the second technique, R/F shells are coated with polyvinylphenol, using a chemical interfacial polymerization technique. Data on surface finish and gas retention for R/F shells coated by both methods are provided

  18. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    KAUST Repository

    Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

    2012-01-01

    Thin shells are found in nature at scales ranging from viruses to hens' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal

  19. L-shell dielectronic recombination for 0-like ions

    International Nuclear Information System (INIS)

    Omar, G.; Semedal, R.; Shahin, F.; El-Sherbini, T.H.

    2007-01-01

    In electron-Ion (e/I) collisions, a free electron may be captured by a positively charged ion having bound electrons with a simultaneous, excitation. This radiationless capture, most probably, creates resonance (d) states. These d- states may stabilize by emission of radiation (x-rays). This two-step process is known as Dielectronic recombination (D R). At high incident-electron energy, D R dominates over the radiative recombination (R R) and three- body recombination (Tbr) processes. Thus, D R is one of the most effective recombination for ionisation balance in solar corona and artificial plasma . In addition, the D R rates are needed for the development of nuclear fusion plasma. Thus, D R is still an interesting process m both experimental and theoretical research. Previously we have done the D R rates for 0-like AL 5+ , Cl 9+ Ti 14+ and Zn 22+ ions with K-shell excitation. In this work, the D R rates are calculated for the same ions, but with L-shell excitation. It is found that, the peak values of the D R rates for L-shell excitation are 1000 times larger than that for K-shell excitation. This means that, D R process is the most efficient mechanism for outer-shell excitations. It is found also that, the Dr rates for L-shell excitation peak at Kt = 6 Ry, 22 Ry for AL 5+ and Ti 14+ ions respectively. These Kt values are much smaller than that for for K-shell excitation

  20. Nanomechanics of biocompatible hollow thin-shell polymer microspheres.

    Science.gov (United States)

    Glynos, Emmanouil; Koutsos, Vasileios; McDicken, W Norman; Moran, Carmel M; Pye, Stephen D; Ross, James A; Sboros, Vassilis

    2009-07-07

    The nanomechanical properties of biocompatible thin-shell hollow polymer microspheres with approximately constant ratio of shell thickness to microsphere diameter were measured by nanocompression tests in aqueous conditions. These microspheres encapsulate an inert gas and are used as ultrasound contrast agents by releasing free microbubbles in the presence of an ultrasound field as a result of free gas leakage from the shell. The tests were performed using an atomic force microscope (AFM) employing the force-distance curve technique. An optical microscope, on which the AFM was mounted, was used to guide the positioning of tipless cantilevers on top of individual microspheres. We performed a systematic study using several cantilevers with spring constants varying from 0.08 to 2.3 N/m on a population of microspheres with diameters from about 2 to 6 microm. The use of several cantilevers with various spring constants allowed a systematic study of the mechanical properties of the microsphere thin shell at different regimes of force and deformation. Using thin-shell mechanics theory for small deformations, the Young's modulus of the thin wall material was estimated and was shown to exhibit a strong size effect: it increased as the shell became thinner. The Young's modulus of thicker microsphere shells converged to the expected value for the macroscopic bulk material. For high applied forces, the force-deformation profiles showed a reversible and/or irreversible nonlinear behavior including "steps" and "jumps" which were attributed to mechanical instabilities such as buckling events.

  1. The protein precursors of peptides that affect the mechanics of connective tissue and/or muscle in the echinoderm Apostichopus japonicus.

    Directory of Open Access Journals (Sweden)

    Maurice R Elphick

    Full Text Available Peptides that cause muscle relaxation or contraction or that modulate electrically-induced muscle contraction have been discovered in the sea cucumber Apostichopus japonicus (Phylum Echinodermata; Class Holothuroidea. By analysing transcriptome sequence data, here the protein precursors of six of these myoactive peptides (the SALMFamides Sticho-MFamide-1 and -2, NGIWYamide, stichopin, GN-19 and GLRFA have been identified, providing novel insights on neuropeptide and endocrine-type signalling systems in echinoderms. The A. japonicus SALMFamide precursor comprises eight putative neuropeptides including both L-type and F-type SALMFamides, which contrasts with previous findings from the sea urchin Strongylocentrotus purpuratus where L-type and F-type SALMFamides are encoded by different genes. The NGIWYamide precursor contains five copies of NGIWYamide but, unlike other NG peptide-type neuropeptide precursors in deuterostomian invertebrates, the NGIWYamide precursor does not have a C-terminal neurophysin domain, indicating loss of this character in holothurians. NGIWYamide was originally discovered as a muscle contractant, but it also causes stiffening of mutable connective tissue in the body wall of A. japonicus, whilst holokinins (PLGYMFR and derivative peptides cause softening of the body wall. However, the mechanisms by which these peptides affect the stiffness of body wall connective tissue are unknown. Interestingly, analysis of the A. japonicus transcriptome reveals that the only protein containing the holokinin sequence PLGYMFR is an alpha-5 type collagen. This suggests that proteolysis of collagen may generate peptides (holokinins that affect body wall stiffness in sea cucumbers, providing a novel perspective on mechanisms of mutable connective tissue in echinoderms.

  2. RNA deep sequencing reveals differential microRNA expression during development of sea urchin and sea star.

    Directory of Open Access Journals (Sweden)

    Sabah Kadri

    Full Text Available microRNAs (miRNAs are small (20-23 nt, non-coding single stranded RNA molecules that act as post-transcriptional regulators of mRNA gene expression. They have been implicated in regulation of developmental processes in diverse organisms. The echinoderms, Strongylocentrotus purpuratus (sea urchin and Patiria miniata (sea star are excellent model organisms for studying development with well-characterized transcriptional networks. However, to date, nothing is known about the role of miRNAs during development in these organisms, except that the genes that are involved in the miRNA biogenesis pathway are expressed during their developmental stages. In this paper, we used Illumina Genome Analyzer (Illumina, Inc. to sequence small RNA libraries in mixed stage population of embryos from one to three days after fertilization of sea urchin and sea star (total of 22,670,000 reads. Analysis of these data revealed the miRNA populations in these two species. We found that 47 and 38 known miRNAs are expressed in sea urchin and sea star, respectively, during early development (32 in common. We also found 13 potentially novel miRNAs in the sea urchin embryonic library. miRNA expression is generally conserved between the two species during development, but 7 miRNAs are highly expressed in only one species. We expect that our two datasets will be a valuable resource for everyone working in the field of developmental biology and the regulatory networks that affect it. The computational pipeline to analyze Illumina reads is available at http://www.benoslab.pitt.edu/services.html.

  3. RNA Deep Sequencing Reveals Differential MicroRNA Expression during Development of Sea Urchin and Sea Star

    Science.gov (United States)

    Kadri, Sabah; Hinman, Veronica F.; Benos, Panayiotis V.

    2011-01-01

    microRNAs (miRNAs) are small (20–23 nt), non-coding single stranded RNA molecules that act as post-transcriptional regulators of mRNA gene expression. They have been implicated in regulation of developmental processes in diverse organisms. The echinoderms, Strongylocentrotus purpuratus (sea urchin) and Patiria miniata (sea star) are excellent model organisms for studying development with well-characterized transcriptional networks. However, to date, nothing is known about the role of miRNAs during development in these organisms, except that the genes that are involved in the miRNA biogenesis pathway are expressed during their developmental stages. In this paper, we used Illumina Genome Analyzer (Illumina, Inc.) to sequence small RNA libraries in mixed stage population of embryos from one to three days after fertilization of sea urchin and sea star (total of 22,670,000 reads). Analysis of these data revealed the miRNA populations in these two species. We found that 47 and 38 known miRNAs are expressed in sea urchin and sea star, respectively, during early development (32 in common). We also found 13 potentially novel miRNAs in the sea urchin embryonic library. miRNA expression is generally conserved between the two species during development, but 7 miRNAs are highly expressed in only one species. We expect that our two datasets will be a valuable resource for everyone working in the field of developmental biology and the regulatory networks that affect it. The computational pipeline to analyze Illumina reads is available at http://www.benoslab.pitt.edu/services.html. PMID:22216218

  4. Perturbation of gut bacteria induces a coordinated cellular immune response in the purple sea urchin larva

    Science.gov (United States)

    CH Ho, Eric; Buckley, Katherine M; Schrankel, Catherine S; Schuh, Nicholas W; Hibino, Taku; Solek, Cynthia M; Bae, Koeun; Wang, Guizhi; Rast, Jonathan P

    2016-01-01

    The purple sea urchin (Strongylocentrotus purpuratus) genome sequence contains a complex repertoire of genes encoding innate immune recognition proteins and homologs of important vertebrate immune regulatory factors. To characterize how this immune system is deployed within an experimentally tractable, intact animal, we investigate the immune capability of the larval stage. Sea urchin embryos and larvae are morphologically simple and transparent, providing an organism-wide model to view immune response at cellular resolution. Here we present evidence for immune function in five mesenchymal cell types based on morphology, behavior and gene expression. Two cell types are phagocytic; the others interact at sites of microbial detection or injury. We characterize immune-associated gene markers for three cell types, including a perforin-like molecule, a scavenger receptor, a complement-like thioester-containing protein and the echinoderm-specific immune response factor 185/333. We elicit larval immune responses by (1) bacterial injection into the blastocoel and (2) seawater exposure to the marine bacterium Vibrio diazotrophicus to perturb immune state in the gut. Exposure at the epithelium induces a strong response in which pigment cells (one type of immune cell) migrate from the ectoderm to interact with the gut epithelium. Bacteria that accumulate in the gut later invade the blastocoel, where they are cleared by phagocytic and granular immune cells. The complexity of this coordinated, dynamic inflammatory program within the simple larval morphology provides a system in which to characterize processes that direct both aspects of the echinoderm-specific immune response as well as those that are shared with other deuterostomes, including vertebrates. PMID:27192936

  5. Experimental ocean acidification alters the allocation of metabolic energy.

    Science.gov (United States)

    Pan, T-C Francis; Applebaum, Scott L; Manahan, Donal T

    2015-04-14

    Energy is required to maintain physiological homeostasis in response to environmental change. Although responses to environmental stressors frequently are assumed to involve high metabolic costs, the biochemical bases of actual energy demands are rarely quantified. We studied the impact of a near-future scenario of ocean acidification [800 µatm partial pressure of CO2 (pCO2)] during the development and growth of an important model organism in developmental and environmental biology, the sea urchin Strongylocentrotus purpuratus. Size, metabolic rate, biochemical content, and gene expression were not different in larvae growing under control and seawater acidification treatments. Measurements limited to those levels of biological analysis did not reveal the biochemical mechanisms of response to ocean acidification that occurred at the cellular level. In vivo rates of protein synthesis and ion transport increased ∼50% under acidification. Importantly, the in vivo physiological increases in ion transport were not predicted from total enzyme activity or gene expression. Under acidification, the increased rates of protein synthesis and ion transport that were sustained in growing larvae collectively accounted for the majority of available ATP (84%). In contrast, embryos and prefeeding and unfed larvae in control treatments allocated on average only 40% of ATP to these same two processes. Understanding the biochemical strategies for accommodating increases in metabolic energy demand and their biological limitations can serve as a quantitative basis for assessing sublethal effects of global change. Variation in the ability to allocate ATP differentially among essential functions may be a key basis of resilience to ocean acidification and other compounding environmental stressors.

  6. Transcriptomics reveal transgenerational effects in purple sea urchin embryos: Adult acclimation to upwelling conditions alters the response of their progeny to differential pCO2 levels.

    Science.gov (United States)

    Wong, Juliet M; Johnson, Kevin M; Kelly, Morgan W; Hofmann, Gretchen E

    2018-03-01

    Understanding the mechanisms with which organisms can respond to a rapidly changing ocean is an important research priority in marine sciences, especially in the light of recent predictions regarding the pace of ocean change in the coming decades. Transgenerational effects, in which the experience of the parental generation can shape the phenotype of their offspring, may serve as such a mechanism. In this study, adult purple sea urchins, Strongylocentrotus purpuratus, were conditioned to regionally and ecologically relevant pCO 2 levels and temperatures representative of upwelling (colder temperature and high pCO 2 ) and nonupwelling (average temperature and low pCO 2 ) conditions typical of coastal upwelling regions in the California Current System. Following 4.5 months of conditioning, adults were spawned and offspring were raised under either high or low pCO 2 levels, to examine the role of maternal effects. Using RNA-seq and comparative transcriptomics, our results indicate that differential conditioning of the adults had an effect on the gene expression patterns of the progeny during the gastrula stage of early development. For example, maternal conditioning under upwelling conditions intensified the transcriptomic response of the progeny when they were raised under high versus low pCO 2 conditions. Additionally, mothers that experienced upwelling conditions produced larger progeny. The overall findings of this study are complex, but do suggest that transgenerational plasticity in situ could act as an important mechanism by which populations might keep pace with rapid environmental change. © 2018 John Wiley & Sons Ltd.

  7. The 3'UTR of nanos2 directs enrichment in the germ cell lineage of the sea urchin.

    Science.gov (United States)

    Oulhen, Nathalie; Yoshida, Takaya; Yajima, Mamiko; Song, Jia L; Sakuma, Tetsushi; Sakamoto, Naoaki; Yamamoto, Takashi; Wessel, Gary M

    2013-05-01

    Nanos is a translational regulator required for the survival and maintenance of primordial germ cells during embryogenesis. Three nanos homologs are present in the genome of the sea urchin Strongylocentrotus purpuratus (Sp), and each nanos mRNA accumulates specifically in the small micromere (sMic) lineage. We found that a highly conserved element in the 3' UTR of nanos2 is sufficient for reporter expression selectively in the sMic lineage: microinjection into a Sp fertilized egg of an RNA that contains the GFP open reading frame followed by Sp nanos2 3'UTR leads to selective reporter enrichment in the small micromeres in blastulae. The same result was seen with nanos2 from the sea urchin Hemicentrotus pulcherrimus (Hp). In both species, the 5'UTR alone is not sufficient for the sMic localization but it always increased the sMic reporter enrichment when present with the 3'UTR. We defined an element conserved between Hp and Sp in the nanos2 3'UTR which is necessary and sufficient for protein enrichment in the sMic, and refer to it as GNARLE (Global Nanos Associated RNA Lability Element). We also found that the nanos2 3'UTR is essential for the selective RNA retention in the small micromeres; GNARLE is required but not sufficient for this process. These results show that a combination of selective RNA retention and translational control mechanisms instills nanos accumulation uniquely in the sMic lineage. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. The 3’UTR of Nanos2 directs enrichment in the germ cell lineage of the sea urchin

    Science.gov (United States)

    Oulhen, Nathalie; Yoshida, Takaya; Yajima, Mamiko; Song, Jia; Sakuma, Tetsushi; Sakamoto, Naoaki; Yamamoto, Takashi; Wessel, Gary M.

    2013-01-01

    Nanos is a translational regulator required for the survival and maintenance of primordial germ cells during embryogenesis. Three nanos homologs are present in the genome of the sea urchin Strongylocentrotus purpuratus (Sp), and each nanos mRNA accumulates specifically in the small micromere (sMic) lineage. We found that a highly conserved element in the 3’ UTR of nanos2 is sufficient for reporter expression selectively in the sMic lineage: microinjection into a Sp fertilized egg of an RNA that contains the GFP open reading frame followed by Sp nanos2 3’UTR leads to selective reporter enrichment in the small micromeres in blastulae. The same result was seen with nanos2 from the sea urchin Hemicentrotus pulcherrimus (Hp). In both species, the 5’UTR alone is not sufficient for the sMic localization but it always increased the sMic reporter enrichment when present with the 3’UTR. We defined an element conserved between Hp and Sp in the nanos2 3’UTR which is necessary and sufficient for protein enrichment in the sMic, and refer to it as GNARLE (Global Nanos Associated RNA Lability Element). We also found that the nanos2 3’UTR is essential for the selective RNA retention in the small micromeres; GNARLE is required but not sufficient for this process. These results show that a combination of selective RNA retention and translational control mechanisms instills nanos accumulation uniquely in the sMic lineage. PMID:23357540

  9. 46 CFR 174.225 - Hull penetrations and shell connections.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection except...

  10. Ancient limpet shells as paleo-environmental and ethno-archaeological archives: the case of Beniguet Island's shell middens (Iroise Sea)

    Science.gov (United States)

    Cudennec, Jean-François; Stephan, Pierre; Dupont, Catherine; Pailler, Yvan; Thébault, Julien; Schöne, Bernd; Paulet, Yves-Marie

    2017-04-01

    During the winter 2013-2014, severe storm events caused a coastal erosion in the southern part of the Beniguet Island (Brittany, France). The associated shoreline retreat had uncovered three layers of shell middens interbedded into an aeolian sand dune deposit. From several radiocarbon dating crossed with the study of ceramic and lithic contents, the shell middens were dated to the Final Neolithic (2400 BC), the Early Bronze Age (2000 BC) and the Early Middle Age (800 AD) respectively. This site offers a unique opportunity to collect two types of information: palaeo-environmental (palaeo-temperature of sea water) and archaeological (determination of harvest season). In this study, we focus on gastropod of the genus Patella which represent 90% of the remains found in this midden. This organism is potentially a highly valuable archive for these environments because they are intertidal and relatively sedentary. We studied the growth rings in the outer calcitic layer of individual limpet shells from the Neolithic, Early Bronze Age and Present Day populations. We report here the results of δ18O analyses. We found a similarity between the reconstructed palaeo-temperature in the Neolithic and the Present periods (between 13 and 14°C in summer and about 8 - 9°C in winter). However, palaeo-temperatures of the Early Bronze Age shells are significantly lower in winter (5 - 6 °C). Moreover, the initial results of the δ18O analyses at the margin of these shells showed that they were harvested during a specific season (end of spring or early summer). Additional work will be done to address questions about shell growth dynamics of these species. These results confirm the interest of using ancient limpet shells as palaeo-environmental and archaeological archives.

  11. Synthesis of Cationic Core-Shell Latex Particles

    NARCIS (Netherlands)

    Dziomkina, N.; Hempenius, Mark A.; Vancso, Gyula J.

    2006-01-01

    Surfactant-free seeded (core-shell) polymerization of cationic polymer colloids is presented. Polystyrene core particles with sizes between 200 nm and 500 nm were synthesized. The number average diameter of the colloidal core particles increased with increasing monomer concentration. Cationic shells

  12. Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

    International Nuclear Information System (INIS)

    Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

    2014-01-01

    We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H 2 or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H 2 and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H 2 , an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H 2 and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated

  13. Reversible patterning of spherical shells through constrained buckling

    Science.gov (United States)

    Marthelot, J.; Brun, P.-T.; Jiménez, F. López; Reis, P. M.

    2017-07-01

    Recent advances in active soft structures envision the large deformations resulting from mechanical instabilities as routes for functional shape morphing. Numerous such examples exist for filamentary and plate systems. However, examples with double-curved shells are rarer, with progress hampered by challenges in fabrication and the complexities involved in analyzing their underlying geometrical nonlinearities. We show that on-demand patterning of hemispherical shells can be achieved through constrained buckling. Their postbuckling response is stabilized by an inner rigid mandrel. Through a combination of experiments, simulations, and scaling analyses, our investigation focuses on the nucleation and evolution of the buckling patterns into a reticulated network of sharp ridges. The geometry of the system, namely, the shell radius and the gap between the shell and the mandrel, is found to be the primary ingredient to set the surface morphology. This prominence of geometry suggests a robust, scalable, and tunable mechanism for reversible shape morphing of elastic shells.

  14. Stresses at the intersection of two cylindrical shells

    International Nuclear Information System (INIS)

    Xue, M.D.; Chen, W.; Hwang, K.C.

    1995-01-01

    The stress analysis based on the theory of a thin shell is carried out for two normally intersecting cylindrical shells with a large diameter ratio. Instead of the Donnell shallow shell equation, the modified Morley equation, which is applicable to ρ 0 (R/T) 1/2 XXXX1, is used for the analysis of the shell with cut-out. The solution in terms of displacement function for the nozzle with a non-planar end is based on the Love equation. The boundary forces and displacements at the intersection are all transformed from Gaussian coordinates (α,β) on the shell, or Gaussian coordinates (ζ,θ) on the nozzle into three-dimensional cylindrical coordinates (ρ,θ,z). Their expressions on the intersecting curve are periodic functions of θ and expanded in Fourier series. Every harmonics of Fourier coefficients of boundary forces and displacements are obtained by numerical quadrature.The results obtained are in agreement with those from the finite element method and experiments for d/D≤0.8. ((orig.))

  15. Study on irradiation preservation of frozen shelled shrimps

    International Nuclear Information System (INIS)

    Liu Chunquan; Zhu Jiating; Zhao Yongfu; Yu Gang; Zhang Weidong; Jin Yudong; Ji Ping

    2004-01-01

    The effect of irradiaiton preservation of frozen shelled shrimps for export was studied. The microbial indexd, nutritional ingredient, physico-chemical index for irradiation frozen shelled shrimps were detected. The results showed that 3-5 kGy irradiation dose could kill more than 99% of all kinds of microorganisms in frozen shelled shrimps, the content of most amino acids in shelled shrimps increased, after being irradiated by 1-9 kGy dose, the total amino acids had been obvisouly higher than CK, the increased range was 0.33%-24.6%, the content of the total volatile basic nitrogen (TVBN) decreased. Compared with the CK, the content of the heavy metal elements etc had no obvious change, the presrvation duration of irradiated shelled shrimp was twelve months longer than that of CK when storage temperature was under -7 degree C soft frozen, Compared with -18 degree C the effect of irradiation preservation had no obvious change. (authors)

  16. Dynamic strength of cylindrical fiber-glass shells and basalt plastic shells under multiple explosive loading

    Science.gov (United States)

    Syrunin, M. A.; Fedorenko, A. G.

    2006-08-01

    We have shown experimentally that, for cylindrical shells made of oriented fiberglass platic and basalt plastic there exists a critical level of deformations, at which a structure sustains a given number of explosions from the inside. The magnitude of critical deformation for cylindrical fiberglass shells depends linearly on the logarithm of the number of loads that cause failure. For a given type of fiberglass, there is a limiting level of explosive action, at which the number of loads that do not lead to failure can be sufficiently large (more than ˜ 102). This level is attained under loads, which are an order of magnitude lower than the limiting loads under a single explosive action. Basalt plastic shells can be repeatedly used even at the loads, which cause deformation by ˜ 30-50% lower than the safe value ˜ 3.3.5% at single loading.

  17. CO{sub 2} capture behavior of shell during calcination/carbonation cycles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.J.; Zhao, C.S.; Chen, H.C.; Duan, L.B.; Chen, X.P. [School of Energy and Environment, Southeast University, Nanjing (China)

    2009-08-15

    The cyclic carbonation performances of shells as CO{sub 2} sorbents were investigated during multiple calcination/carbonation cycles. The carbonation kinetics of the shell and limestone are similar since they both exhibit a fast kinetically controlled reaction regime and a diffusion controlled reaction regime, but their carbonation rates differ between these two regions. Shell achieves the maximum carbonation conversion for carbonation at 680-700 C. The mactra veneriformis shell and mussel shell exhibit higher carbonation conversions than limestone after several cycles at the same reaction conditions. The carbonation conversion of scallop shell is slightly higher than that of limestone after a series of cycles. The calcined shell appears more porous than calcined limestone, and possesses more pores >230 nm, which allow large CO{sub 2} diffusion-carbonation reaction rates and higher conversion due to the increased surface area of the shell. The pores of the shell that are greater than 230 nm do not sinter significantly. The shell has more sodium ions than limestone, which probably leads to an improvement in the cyclic carbonation performance during the multiple calcination/carbonation cycles. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Core-shell polymer nanorods by a two-step template wetting process

    International Nuclear Information System (INIS)

    Dougherty, S; Liang, J

    2009-01-01

    One-dimensional core-shell polymer nanowires offer many advantages and great potential for many different applications. In this paper we introduce a highly versatile two-step template wetting process to fabricate two-component core-shell polymer nanowires with controllable shell thickness. PLLA and PMMA were chosen as model polymers to demonstrate the feasibility of this process. Solution wetting with different concentrations of polymer solutions was used to fabricate the shell layer and melt wetting was used to fill the shell with the core polymer. The shell thickness was analyzed as a function of the polymer solution concentration and viscosity, and the core-shell morphology was observed with TEM. This paper demonstrates the feasibility of fabricating polymer core-shell nanostructures using our two-step template wetting process and opens the arena for optimization and future experiments with polymers that are desirable for specific applications.

  19. Properties of Activated Carbon Prepared from Coconut Shells in ...

    African Journals Online (AJOL)

    Materials commonly used for preparation of activated carbons include coal and coconut shells. Ghana generates over 30,000 tonnes of coconut shells annually from coconut oil processing activities but apart from a small percentage of the shells, which is burned as fuel, the remaining is usually dumped as waste.

  20. On the dynamics of relativistic multi-layer spherical shell systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, Merse E; Racz, Istvan, E-mail: merse@rmki.kfki.hu, E-mail: iracz@rmki.kfki.hu [RMKI, H-1121 Budapest, Konkoly Thege Miklos ut 29-33, Budapest (Hungary)

    2011-04-21

    The relativistic time evolution of multi-layer spherically symmetric shell systems-consisting of infinitely thin shells separated by vacuum regions-is examined. Whenever two shells collide the evolution is continued with the assumption that the collision is totally transparent. The time evolution of various multi-layer shell systems-comprising large number of shells thereby mimicking the behavior of a thick shell making it possible to study the formation of acoustic singularities-is analyzed numerically and compared in certain cases to the corresponding Newtonian time evolution. The analytic setup is chosen such that the developed code is capable of following the evolution even inside the black hole region. This, in particular, allowed us to investigate the mass inflation phenomenon in the chosen framework.

  1. Multidimensional Analysis of Direct-Drive Plastic-Shell Implosions on OMEGA

    Science.gov (United States)

    Radha, P. B.

    2004-11-01

    Direct-drive implosions of plastic shells with the OMEGA laser are used as energy-scaled warm surrogates for ignition cryogenic targets designed for use on the National Ignition Facility. Plastic targets involve varying shell thickness (15 to 33 μm), fill pressures (3 to 15 atm), and shell adiabats. The multidimensional hydrodynamics code DRACO is used to evaluate the effects of capsule-surface roughness and illumination nonuniformities on target performance. These simulations indicate that shell stability during the acceleration phase plays a critical role in determining fusion yields. For shells that are thick enough to survive the Rayleigh--Taylor growth, target yields are significantly reduced by growth of the long (ℓ surrogacy between these plastic-shell implosions and the cryogenic ignition designs.

  2. Ni@Ru and NiCo@Ru Core-Shell Hexagonal Nanosandwiches with a Compositionally Tunable Core and a Regioselectively Grown Shell.

    Science.gov (United States)

    Hwang, Hyeyoun; Kwon, Taehyun; Kim, Ho Young; Park, Jongsik; Oh, Aram; Kim, Byeongyoon; Baik, Hionsuck; Joo, Sang Hoon; Lee, Kwangyeol

    2018-01-01

    The development of highly active electrocatalysts is crucial for the advancement of renewable energy conversion devices. The design of core-shell nanoparticle catalysts represents a promising approach to boost catalytic activity as well as save the use of expensive precious metals. Here, a simple, one-step synthetic route is reported to prepare hexagonal nanosandwich-shaped Ni@Ru core-shell nanoparticles (Ni@Ru HNS), in which Ru shell layers are overgrown in a regioselective manner on the top and bottom, and around the center section of a hexagonal Ni nanoplate core. Notably, the synthesis can be extended to NiCo@Ru core-shell nanoparticles with tunable core compositions (Ni 3 Co x @Ru HNS). Core-shell HNS structures show superior electrocatalytic activity for the oxygen evolution reaction (OER) to a commercial RuO 2 black catalyst, with their OER activity being dependent on their core compositions. The observed trend in OER activity is correlated to the population of Ru oxide (Ru 4+ ) species, which can be modulated by the core compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Learning Shell scripting with Zsh

    CERN Document Server

    Festari, Gaston

    2014-01-01

    A step-by-step tutorial that will teach you, through real-world examples, how to configure and use Zsh and its various features. If you are a system administrator, developer, or computer professional involved with UNIX who are looking to improve on their daily tasks involving the UNIX shell, ""Learning Shell Scripting with Zsh"" will be great for you. It's assumed that you have some familiarity with an UNIX command-line interface and feel comfortable with editors such as Emacs or vi.

  4. 40 Years of Shell Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-02-15

    Shell has been using scenario planning for four decades. During that time these scenarios have helped the company and governments across the world to make better strategic choices. Scenarios provide lenses that help see future prospects more clearly, make richer judgments and be more sensitive to uncertainties. Discover how the Shell Scenarios team has helped guide decision makers at major moments in history and get a peek at the team future focus, including the intricate relationship between energy, water and food.

  5. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., 90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions, equilibrium carbon isotope fractionation

  6. Evolution of shell gaps with neutron richness

    International Nuclear Information System (INIS)

    Basu, Moumita Ray; Ray, I.; Kshetri, Ritesh; Saha Sarkar, M.; Sarkar, S.

    2006-01-01

    In the present work, an attempt has been made to coordinate the recent data available over the periodic table, specially near the shell gaps and studied the evolution of the shell gaps as function of neutron numbers and/or other related quantities

  7. Radiometric measuring method for egg shells

    Energy Technology Data Exchange (ETDEWEB)

    Forberg, S; Svaerdstroem, K

    1973-02-01

    A description is given of a fast nondestructive radiometric method for registration of the thickness of egg shells of the tawny owl, hen, osprey, and Canada goose. Certain errors are discussed. Measurement of the thickness of egg shells (mineral content per cm/sup 2/) with an accuracy better than 1% is possible in less than one minute under field conditions. (auth)

  8. Size-exclusion chromatography using core-shell particles.

    Science.gov (United States)

    Pirok, Bob W J; Breuer, Pascal; Hoppe, Serafine J M; Chitty, Mike; Welch, Emmet; Farkas, Tivadar; van der Wal, Sjoerd; Peters, Ron; Schoenmakers, Peter J

    2017-02-24

    Size-exclusion chromatography (SEC) is an indispensable technique for the separation of high-molecular-weight analytes and for determining molar-mass distributions. The potential application of SEC as second-dimension separation in comprehensive two-dimensional liquid chromatography demands very short analysis times. Liquid chromatography benefits from the advent of highly efficient core-shell packing materials, but because of the reduced total pore volume these materials have so far not been explored in SEC. The feasibility of using core-shell particles in SEC has been investigated and contemporary core-shell materials were compared with conventional packing materials for SEC. Columns packed with very small core-shell particles showed excellent resolution in specific molar-mass ranges, depending on the pore size. The analysis times were about an order of magnitude shorter than what could be achieved using conventional SEC columns. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Shell model description of Ge isotopes

    International Nuclear Information System (INIS)

    Hirsch, J G; Srivastava, P C

    2012-01-01

    A shell model study of the low energy region of the spectra in Ge isotopes for 38 ≤ N ≤ 50 is presented, analyzing the excitation energies, quadrupole moments, B(E2) values and occupation numbers. The theoretical results have been compared with the available experimental data. The shell model calculations have been performed employing three different effective interactions and valence spaces. We have used two effective shell model interactions, JUN45 and jj44b, for the valence space f 5/2 pg 9/2 without truncation. To include the proton subshell f 7/2 in valence space we have employed the fpg effective interaction due to Sorlin et al., with 48 Ca as a core and a truncation in the number of excited particles.

  10. Complete Surface Mapping of ICF Shells

    International Nuclear Information System (INIS)

    Stephens, R.B.; Olson, D.; Huang, H.; Gibson, J.B.

    2004-01-01

    Inertial confinement fusion shells have previously been evaluated on the basis of microscopic examination for local defects and limited surface profiling to represent their average fluctuation power. Since defects are local, and don't always have visible edges, this approach both misses some important fluctuations and doesn't properly represent the spatially dependent surface fluctuation power. We have taken the first step toward correcting this problem by demonstrating the capability to completely map the surface of a NIF shell with the resolution to account for all modes. This allows complete accounting of all the surface fluctuations. In the future this capability could be used for valuable shells to generate a complete r(θ, φ) surface map for accurate 3-D modeling of a shot

  11. COMPLETE SURFACE MAPPING OF ICF SHELLS

    International Nuclear Information System (INIS)

    STEPHENS, R.B.; OLSON, D.; HUANG, H.; GIBSON, J.B.

    2003-09-01

    OAK-B135 Inertial confinement fusion shells have previously been evaluated on the basis of microscopic examination for local defects and limited surface profiling to represent their average fluctuation power. Since defects are local, and don't always have visible edges, this approach both misses some important fluctuations and doesn't properly represent the spatially dependent surface fluctuation power. they have taken the first step toward correcting this problem by demonstrating the capability to completely map the surface of a NIF shell with the resolution to account for all modes. This allows complete accounting of all the surface fluctuations. In the future this capability could be used for valuable shells to generate a complete r(θ,ψ) surface map for accurate 3-D modeling of a shot

  12. Ethanol production of banana shell and cassava starch

    International Nuclear Information System (INIS)

    Monsalve G, John F; Medina de Perez, Victoria Isabel; Ruiz colorado, Angela Adriana

    2006-01-01

    In this work the acid hydrolysis of the starch was evaluated in cassava and the cellulose shell banana and its later fermentation to ethanol, the means of fermentation were adjusted for the microorganisms saccharomyces cerevisiae nrrl y-2034 and zymomonas mobilis cp4. The banana shell has been characterized, which possesses a content of starch, cellulose and hemicelluloses that represent more than 80% of the shell deserve the study of this as source of carbon. The acid hydrolysis of the banana shell yield 20g/l reducing sugar was obtained as maximum concentration. For the cassava with 170 g/l of starch to ph 0.8 in 5 hours complete conversion is achieved to you reducing sugars and any inhibitory effect is not noticed on the part of the cultivations carried out with banana shell and cassava by the cyanide presence in the cassava and for the formation of toxic compounds in the acid hydrolysis the cellulose in banana shell. For the fermentation carried out with saccharomyces cerevisiae a concentration of ethanol of 7.92± 0.31% it is achieved and a considerable production of ethanol is not appreciated (smaller than 0.1 g/l) for none of the means fermented with zymomonas mobilis

  13. Morphology and properties of periwinkle shell asbestos-free brake pad

    Directory of Open Access Journals (Sweden)

    D.S. Yawas

    2016-01-01

    Full Text Available The development of asbestos-free automotive brake pad using periwinkle shell particles as frictional filler material is presented. This was with a view to exploiting the characteristics of the periwinkle shell, which is largely deposited as a waste, in replacing asbestos which has been found to be carcinogenic. Five sets of brake pads with different sieve size (710–125 μm of periwinkle shell particles with 35% resin were produced using compressive moulding. The physical, mechanical and tribological properties of the periwinkle shell particle-based brake pads were evaluated and compared with the values for the asbestos-based brake pads. The results obtained showed that compressive strength, hardness and density of the developed brake pad samples increased with decreasing the particle size of periwinkle shell from 710 to 125 μm, while the oil soak, water soak and wear rate decreased with decreasing the particle size of periwinkle shell. The results obtained at 125 μm of periwinkle shell particles compared favourably with that of commercial brake pad. The results of this research indicate that periwinkle shell particles can be effectively used as a replacement for asbestos in brake pad manufacture.

  14. Theory of elastic thin shells solid and structural mechanics

    CERN Document Server

    Gol'Denveizer, A L; Dryden, H L

    1961-01-01

    Theory of Elastic Thin Shells discusses the mathematical foundations of shell theory and the approximate methods of solution. The present volume was originally published in Russian in 1953, and remains the only text which formulates as completely as possible the different sets of basic equations and various approximate methods of shell analysis emphasizing asymptotic integration. The book is organized into five parts. Part I presents the general formulation and equations of the theory of shells, which are based on the well-known hypothesis of the preservation of the normal element. Part II is

  15. Emulsion preparation for novel micro-porous polymeric hemi-shells

    CSIR Research Space (South Africa)

    Naidoo, Kersch

    2008-01-01

    Full Text Available -dichloromethane (DCM) oil phase , micro-porous hemi-shells formed as solvent evaporated. CO2 gas ) 252–254 www.elsevier.com/locate/matlet Polycaprolactone hemi-shells were prepared by using an O/W technique. PCL (15% w/v) was fully dissolved in 10ml DCM (oil 253K...-averaged particle size and hemi-shell yield with solvent evaporation time. (ImageJ, NIH), the number-average particle size and yield of hemi-shells were obtained with increasing time intervals (n=200). Scanning electron microscopy (LEO 1525 field emis- sion SEM...

  16. On the accuracy of the asymptotic theory for cylindrical shells

    DEFF Research Database (Denmark)

    Niordson, Frithiof; Niordson, Christian

    1999-01-01

    We study the accuracy of the lowest-order bending theory of shells, derived from an asymptotic expansion of the three-dimensional theory of elasticity, by comparing the results of this shell theory for a cylindrical shell with clamped ends with the results of a solution to the three......-dimensional problem. The results are also compared with those of some commonly used engineering shell theories....

  17. Broadband absorption and enhanced photothermal conversion property of octopod-like Ag@Ag2S core@shell structures with gradually varying shell thickness.

    Science.gov (United States)

    Jiang, Qian; Zeng, Wenxia; Zhang, Canying; Meng, Zhaoguo; Wu, Jiawei; Zhu, Qunzhi; Wu, Daxiong; Zhu, Haitao

    2017-12-19

    Photothermal conversion materials have promising applications in many fields and therefore they have attracted tremendous attention. However, the multi-functionalization of a single nanostructure to meet the requirements of multiple photothermal applications is still a challenge. The difficulty is that most nanostructures have specific absoprtion band and are not flexible to different demands. In the current work, we reported the synthesis and multi-band photothermal conversion of Ag@Ag 2 S core@shell structures with gradually varying shell thickness. We synthesized the core@shell structures through the sulfidation of Ag nanocubes by taking the advantage of their spatially different reactivity. The resulting core@shell structures show an octopod-like mopgorlogy with a Ag 2 S bulge sitting at each corner of the Ag nanocubes. The thickness of the Ag 2 S shell gradually increases from the central surface towards the corners of the structure. The synthesized core@shell structures show a broad band absorption spectrum from 300 to 1100 nm. Enhanced photothermal conversion effect is observed under the illuminations of 635, 808, and 1064 nm lasers. The results indicate that the octopod-like Ag@Ag 2 S core@shell structures have characteristics of multi-band photothermal conversion. The current work might provide a guidance for the design and synthesis of multifunctional photothermal conversion materials.

  18. Microwave moisture meter for in-shell almonds.

    Science.gov (United States)

    Determining almond kernel moisture content while still in the shell is important for both almond growers and processors. A dielectric method was developed for almond kernel moisture determination from dielectric measurements on in-shell almonds at a single microwave frequency. A sample holder was fi...

  19. On the mechanics of elastic lines in thin shells

    Science.gov (United States)

    Benet, Eduard; Vernerey, Franck

    The deformation of soft shells in nature and engineering is often conditioned by the presence of lines whose mechanical properties are different from the shell. For instance, the deformation of tree leaves is conditioned by the presence of harder stems, and cell mitosis is driven by a stiffening line along its membrane. From an experimental standpoint, many groups have taken advantage of this feature to develop self-actuated shells with prescribed deformations. Examples include the polymerization of gels along certain lines, or the inclusion of stiffer lines via 3D printing. However, there is not yet a general continuum theory that accounts for this type of discontinuity within the membrane. Hence, we extend the general shell theory to account for the inclusion of a line that potentially induces jumps in stresses, couple stresses and moments, across its thickness. This is achieved via coupling the rod and the membrane deformations, and ensuring continuity of displacements. The model is then applied to three important problems: a constriction disc inside a shell of revolution, the induced twisting of a shell via the torsion of an embedded line, and the effect of an helicoidal line on the uni-axial deformation of a cylindrical shell. National Science Foundation CAREER award 1350090.

  20. A finite-element for the analysis of shell intersections

    International Nuclear Information System (INIS)

    Koves, W.J.; Nair, S.

    1994-01-01

    The analysis of discontinuity stresses at shell intersections is a problem of great importance in several major industries. Some of the major areas of interest are pressure-containing equipment, such as reactors and piping, in the nuclear and fossil power industry; pressure vessels and heat exchangers in the petrochemical industry; bracing in offshore oil platforms; and aerospace structures. A specialized shell-intersection finite element, which is compatible with adjoining shell elements, has been developed that has the capability of physically representing the complex three-dimensional geometry and stress state at shell intersections. The element geometry is a contoured shape that matches a wide variety of practical nozzle configurations used in ASME Code pressure vessel construction, and allows computational rigor. A closed-form theory of elasticity solution was used to compute the stress state and strain energy in the element. The concept of an energy-equivalent nodal displacement and force vector set was then developed to allow complete compatibility with adjoining shell elements and retain the analytical rigor within the element. This methodology provides a powerful and robust computation scheme that maintains the computational efficiency of shell element solutions. The shell-intersection element was then applied to the cylinder-sphere and cylinder-cylinder intersection problems

  1. Thin shells joining local cosmic string geometries

    Energy Technology Data Exchange (ETDEWEB)

    Eiroa, Ernesto F. [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Rubin de Celis, Emilio; Simeone, Claudio [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Ciudad Universitaria Pabellon I, IFIBA-CONICET, Buenos Aires (Argentina)

    2016-10-15

    In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)

  2. Thin shells joining local cosmic string geometries

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Rubin de Celis, Emilio; Simeone, Claudio

    2016-01-01

    In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)

  3. Microsoft Exchange Server 2013 PowerShell cookbook

    CERN Document Server

    Andersson, Jonas

    2013-01-01

    This book is written in a Cookbook-style format and provides practical, immediately usable task-based recipes that show you how to manage and maintain your Microsoft Exchange Server 2013 environment with Windows PowerShell 3. Each chapter of the book is written so that it can be used as a desktop reference, or it can be read from beginning to end, allowing you to build a solid foundation for building scripts in your Exchange environment.This Cookbook is for messaging professionals who want to learn how to build real-world scripts with Windows PowerShell 3 and the Exchange Management Shell. If

  4. Analysis of anisotropic shells containing flowing fluid

    International Nuclear Information System (INIS)

    Lakis, A.A.

    1983-01-01

    A general theory for the dynamic analysis of anisotropic thin cylindrical shells containing flowing fluid is presented. The shell may be uniform or non-uniform, provided it is geometrically axially symmetric. This is a finite- element theory, using cylindrical finite elements, but the displacement functions are determined by using classical shell theory. A new solution of the wave equation of the liquid finite element leads to an expression of the fluid pressure, p, as a function of the nodal displacements of the element and three operative forces (inertia, centrifugal and Coriolis) of the moving fluid. (Author) [pt

  5. CIRCUMSTELLAR SHELL FORMATION IN SYMBIOTIC RECURRENT NOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Kevin; Bildsten, Lars [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106 (United States)

    2012-12-20

    We present models of spherically symmetric recurrent nova shells interacting with circumstellar material (CSM) in a symbiotic system composed of a red giant (RG) expelling a wind and a white dwarf accreting from this material. Recurrent nova eruptions periodically eject material at high velocities ({approx}> 10{sup 3} km s{sup -1}) into the RG wind profile, creating a decelerating shock wave as CSM is swept up. High CSM densities cause the shocked wind and ejecta to have very short cooling times of days to weeks. Thus, the late-time evolution of the shell is determined by momentum conservation instead of energy conservation. We compute and show evolutionary tracks of shell deceleration, as well as post-shock structure. After sweeping up all the RG wind, the shell coasts at a velocity {approx}100 km s{sup -1}, depending on system parameters. These velocities are similar to those measured in blueshifted CSM from the symbiotic nova RS Oph, as well as a few Type Ia supernovae that show evidence of CSM, such as 2006X, 2007le, and PTF 11kx. Supernovae occurring in such systems may not show CSM interaction until the inner nova shell gets hit by the supernova ejecta, days to months after the explosion.

  6. Open source integrated modeling environment Delta Shell

    Science.gov (United States)

    Donchyts, G.; Baart, F.; Jagers, B.; van Putten, H.

    2012-04-01

    In the last decade, integrated modelling has become a very popular topic in environmental modelling since it helps solving problems, which is difficult to model using a single model. However, managing complexity of integrated models and minimizing time required for their setup remains a challenging task. The integrated modelling environment Delta Shell simplifies this task. The software components of Delta Shell are easy to reuse separately from each other as well as a part of integrated environment that can run in a command-line or a graphical user interface mode. The most components of the Delta Shell are developed using C# programming language and include libraries used to define, save and visualize various scientific data structures as well as coupled model configurations. Here we present two examples showing how Delta Shell simplifies process of setting up integrated models from the end user and developer perspectives. The first example shows coupling of a rainfall-runoff, a river flow and a run-time control models. The second example shows how coastal morphological database integrates with the coastal morphological model (XBeach) and a custom nourishment designer. Delta Shell is also available as open-source software released under LGPL license and accessible via http://oss.deltares.nl.

  7. Multimode interaction in axially excited cylindrical shells

    Directory of Open Access Journals (Sweden)

    Silva F. M. A.

    2014-01-01

    Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.

  8. Functions and Requirements for Automated Liquid Level Gauge Instruments in Single-Shell and Double-Shell Tank Farms

    International Nuclear Information System (INIS)

    CARPENTER, K.E.

    1999-01-01

    This functions and requirements document defines the baseline requirements and criteria for the design, purchase, fabrication, construction, installation, and operation of automated liquid level gauge instruments in the Tank Farms. This document is intended to become the technical baseline for current and future installation, operation and maintenance of automated liquid level gauges in single-shell and double-shell tank farms

  9. Experiment on vibration in water of a cylindrical shell fixed in water; Suichu ni koteisareta ento shell no sessui shindo jikken

    Energy Technology Data Exchange (ETDEWEB)

    Toyota, K; Yasuzawa, Y; Kagawa, K; Nanatsuya, Y [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1996-04-10

    In order to utilize more effectively wide oceanic spaces, a feasibility study is performed on submerged large shell structures from the aspect of structural engineerings. As part of the study, for the purpose of deriving dynamic response characteristics of a structure, development was made on a numerical analysis code, `DASOR`, required to analyze natural frequency of a rotating shell fixed in water. The `DASOR` is a dynamic analysis code to derive added water mass effect, and effects of water depth on the dynamic response characteristics based on the shell theory by Donnell-Mushtari-Vlasov. This paper describes an experiment using a cylindrical shell to elucidate effects of the cylindrical shell on vibration characteristics due to contact with water. Comparisons and discussions were given on the result of numerical calculation using the `DASOR`, solution of a simplified theory analysis, and the result of the experiment to make clear the reasonability of the `DASOR`. The cylindrical shell in water has its natural frequency decreased due to the added water mass effect in association with increase in the water level. The `DASOR` showed good agreement with the experimental values as a result of giving considerations on the boundary conditions, by which its reasonability was verified. 3 refs., 9 figs., 2 tabs.

  10. Gene expression correlated with delay in shell formation in larval Pacific oysters (Crassostrea gigas) exposed to experimental ocean acidification provides insights into shell formation mechanisms.

    Science.gov (United States)

    De Wit, Pierre; Durland, Evan; Ventura, Alexander; Langdon, Chris J

    2018-02-22

    Despite recent work to characterize gene expression changes associated with larval development in oysters, the mechanism by which the larval shell is first formed is still largely unknown. In Crassostrea gigas, this shell forms within the first 24 h post fertilization, and it has been demonstrated that changes in water chemistry can cause delays in shell formation, shell deformations and higher mortality rates. In this study, we use the delay in shell formation associated with exposure to CO 2 -acidified seawater to identify genes correlated with initial shell deposition. By fitting linear models to gene expression data in ambient and low aragonite saturation treatments, we are able to isolate 37 annotated genes correlated with initial larval shell formation, which can be categorized into 1) ion transporters, 2) shell matrix proteins and 3) protease inhibitors. Clustering of the gene expression data into co-expression networks further supports the result of the linear models, and also implies an important role of dynein motor proteins as transporters of cellular components during the initial shell formation process. Using an RNA-Seq approach with high temporal resolution allows us to identify a conceptual model for how oyster larval calcification is initiated. This work provides a foundation for further studies on how genetic variation in these identified genes could affect fitness of oyster populations subjected to future environmental changes, such as ocean acidification.

  11. Skeletal remodelling suggests the turtle's shell is not an evolutionary straitjacket.

    Science.gov (United States)

    Cordero, Gerardo Antonio; Quinteros, Kevin

    2015-04-01

    Recent efforts to decipher the enigma of the turtle's shell revealed that distantly related turtle species deploy diverse processes during shell development. Even so, extant species share in common a shoulder blade (scapula) that is encapsulated within the shell. Thus, evolutionary change in the correlated development of the shell and scapula probably underpins the evolution of highly derived shell morphologies. To address this expectation, we conducted one of the most phylogenetically comprehensive surveys of turtle development, focusing on scapula growth and differentiation in embryos, hatchlings and adults of 13 species. We report, to our knowledge, the first description of secondary differentiation owing to skeletal remodelling of the tetrapod scapula in turtles with the most structurally derived shell phenotypes. Remodelling and secondary differentiation late in embryogenesis of box turtles (Emys and Terrapene) yielded a novel skeletal segment (i.e. the suprascapula) of high functional value to their complex shell-closing system. Remarkably, our analyses suggest that, in soft-shelled turtles (Trionychidae) with extremely flattened shells, a similar transformation is linked to truncated scapula growth. Skeletal remodelling, as a form of developmental plasticity, might enable the seemingly constrained turtle body plan to diversify, suggesting the shell is not an evolutionary straitjacket. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  12. A new method to make poly acrylate foam shells

    International Nuclear Information System (INIS)

    Fan Yongheng; Luo Xuan; Fang Yu; Ren Hongbo; Zhang Lin; Cui Yi

    2009-01-01

    A triple-orifice droplet generator was designed and developed for the size-controllable continuous fabrication of hollow foam micro-shells. Solutions of an internal water phase, an oil phase (trimethylpropane triacrylate monomer, dibutyl phthalate solvent, and benzoin ethyl ether initiator), and an external water phase were used to prepare micro-shells whose diameters are between 1.5 mm and 4.0 mm successfully. Characterization of the foam shells was carried out using a scanning electron microscope and X-ray radiography. The results show that cell diameters of the shells are not above 1 um. The refractive index of the polymer framework is around 1.50. Furthermore, the shells fabricated through the triple-orifice droplet generator have a high survival probability of 93% and exhibit narrow size distribution. (authors)

  13. A general and high-yield galvanic displacement approach to Au-M (M = Au, Pd, and Pt) core-shell nanostructures with porous shells and enhanced electrocatalytic performances.

    Science.gov (United States)

    Kuai, Long; Geng, Baoyou; Wang, Shaozhen; Sang, Yan

    2012-07-23

    In this work, we utilize the galvanic displacement synthesis and make it a general and efficient method for the preparation of Au-M (M = Au, Pd, and Pt) core-shell nanostructures with porous shells, which consist of multilayer nanoparticles. The method is generally applicable to the preparation of Au-Au, Au-Pd, and Au-Pt core-shell nanostructures with typical porous shells. Moreover, the Au-Au isomeric core-shell nanostructure is reported for the first time. The lower oxidation states of Au(I), Pd(II), and Pt(II) are supposed to contribute to the formation of porous core-shell nanostructures instead of yolk-shell nanostructures. The electrocatalytic ethanol oxidation and oxygen reduction reaction (ORR) performance of porous Au-Pd core-shell nanostructures are assessed as a typical example for the investigation of the advantages of the obtained core-shell nanostructures. As expected, the Au-Pd core-shell nanostructure indeed exhibits a significantly reduced overpotential (the peak potential is shifted in the positive direction by 44 mV and 32 mV), a much improved CO tolerance (I(f)/I(b) is 3.6 and 1.63 times higher), and an enhanced catalytic stability in comparison with Pd nanoparticles and Pt/C catalysts. Thus, porous Au-M (M = Au, Pd, and Pt) core-shell nanostructures may provide many opportunities in the fields of organic catalysis, direct alcohol fuel cells, surface-enhanced Raman scattering, and so forth. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Skeletal remodelling suggests the turtle's shell is not an evolutionary straitjacket

    OpenAIRE

    Cordero, Gerardo Antonio; Quinteros, Kevin

    2015-01-01

    Recent efforts to decipher the enigma of the turtle's shell revealed that distantly related turtle species deploy diverse processes during shell development. Even so, extant species share in common a shoulder blade (scapula) that is encapsulated within the shell. Thus, evolutionary change in the correlated development of the shell and scapula probably underpins the evolution of highly derived shell morphologies. To address this expectation, we conducted one of the most phylogenetically compre...

  15. Sidewall coring shell

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Ya A; Konstantinov, L P; Martyshin, A N

    1966-12-12

    A sidewall coring shell consists of a housing and a detachable core catcher. The core lifter is provided with projections, the ends of which are situated in another plane, along the longitudinal axis of the lifter. The chamber has corresponding projections.

  16. Walnut shells: replacement for natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Goss, J R; Williams, R O

    1977-11-01

    A method of extracting useful energy from cracked walnut shells has been developed by the University of California in co-operation with Diamond/Sunsweet, Inc., and the California Energy Resources Conservation and Development Commission. The technique involves converting the shells to producer gas, a low-Btu gas in which the major combustible components are carbon monoxide (20 to 30%) and hydrogen (10 to 15%).

  17. Nonlinear Vibration and Mode Shapes of FG Cylindrical Shells

    Directory of Open Access Journals (Sweden)

    Saeed Mahmoudkhani

    Full Text Available Abstract The nonlinear vibration and normal mode shapes of FG cylindrical shells are investigated using an efficient analytical method. The equations of motion of the shell are based on the Donnell’s non-linear shallow-shell, and the material is assumed to be gradually changed across the thickness according to the simple power law. The solution is provided by first discretizing the equations of motion using the multi-mode Galerkin’s method. The nonlinear normal mode of the system is then extracted using the invariant manifold approach and employed to decouple the discretized equations. The homotopy analysis method is finally used to determine the nonlinear frequency. Numerical results are presented for the backbone curves of FG cylindrical shells, nonlinear mode shapes and also the nonlinear invariant modal surfaces. The volume fraction index and the geometric properties of the shell are found to be effective on the type of nonlinear behavior and also the nonlinear mode shapes of the shell. The circumferential half-wave numbers of the nonlinear mode shapes are found to change with time especially in a thinner cylinder.

  18. Metal shell technology based upon hollow jet instability

    International Nuclear Information System (INIS)

    Kendall, J.M.; Lee, M.C.; Wang, T.G.

    1982-01-01

    Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. We describe a technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal. We have produced shells in the 0.7--2.0 mm size range using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold--lead--antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise

  19. A shell approach for fibrous reinforcement forming simulations

    Science.gov (United States)

    Liang, B.; Colmars, J.; Boisse, P.

    2018-05-01

    Because of the slippage between fibers, the basic assumptions of classical plate and shell theories are not verified by fiber reinforcement during a forming. However, simulations of reinforcement forming use shell finite elements when wrinkles development is important. A shell formulation is proposed for the forming simulations of continuous fiber reinforcements. The large tensile stiffness leads to the quasi inextensibility in the fiber directions. The fiber bending stiffness determines the curvature of the reinforcement. The calculation of tensile and bending virtual works are based on the precise geometry of the single fiber. Simulations and experiments are compared for different reinforcements. It is shown that the proposed fibrous shell approach not only correctly simulates the deflections but also the rotations of the through thickness material normals.

  20. Wireless energy transfer between anisotropic metamaterials shells

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José, E-mail: jsdehesa@upv.es

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  1. Wireless energy transfer between anisotropic metamaterials shells

    International Nuclear Information System (INIS)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José

    2014-01-01

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted

  2. Computational mechanics of nonlinear response of shells

    Energy Technology Data Exchange (ETDEWEB)

    Kraetzig, W.B. (Bochum Univ. (Germany, F.R.). Inst. fuer Statik und Dynamik); Onate, E. (Universidad Politecnica de Cataluna, Barcelona (Spain). Escuela Tecnica Superior de Ingenieros de Caminos) (eds.)

    1990-01-01

    Shell structures and their components are utilized in a wide spectrum of engineering fields reaching from space and aircraft structures, pipes and pressure vessels over liquid storage tanks, off-shore installations, cooling towers and domes, to bodyworks of motor vehicles. Of continuously increasing importance is their nonlinear behavior, in which large deformations and large rotations are involved as well as nonlinear material properties. The book starts with a survey about nonlinear shell theories from the rigorous point of view of continuum mechanics, this starting point being unavoidable for modern computational concepts. There follows a series of papers on nonlinear, especially unstable shell responses, which draw computational connections to well established tools in the field of static and dynamic stability of systems. Several papers are then concerned with new finite element derivations for nonlinear shell problems, and finally a series of authors contribute to specific applications opening a small window of the above mentioned wide spectrum. (orig./HP) With 159 figs.

  3. Computational mechanics of nonlinear response of shells

    International Nuclear Information System (INIS)

    Kraetzig, W.B.; Onate, E.

    1990-01-01

    Shell structures and their components are utilized in a wide spectrum of engineering fields reaching from space and aircraft structures, pipes and pressure vessels over liquid storage tanks, off-shore installations, cooling towers and domes, to bodyworks of motor vehicles. Of continuously increasing importance is their nonlinear behavior, in which large deformations and large rotations are involved as well as nonlinear material properties. The book starts with a survey about nonlinear shell theories from the rigorous point of view of continuum mechanics, this starting point being unavoidable for modern computational concepts. There follows a series of papers on nonlinear, especially unstable shell responses, which draw computational connections to well established tools in the field of static and dynamic stability of systems. Several papers are then concerned with new finite element derivations for nonlinear shell problems, and finally a series of authors contribute to specific applications opening a small window of the above mentioned wide spectrum. (orig./HP) With 159 figs

  4. Finite element model for nonlinear shells of revolution

    International Nuclear Information System (INIS)

    Cook, W.A.

    1979-01-01

    Nuclear material shipping containers have shells of revolution as basic structural components. Analytically modeling the response of these containers to severe accident impact conditions requires a nonlinear shell-of-revolution model that accounts for both geometric and material nonlinearities. Existing models are limited to large displacements, small rotations, and nonlinear materials. The paper presents a finite element model for a nonlinear shell of revolution that will account for large displacements, large strains, large rotations, and nonlinear materials

  5. Effects of egg shell quality and washing on Salmonella Infantis penetration.

    Science.gov (United States)

    Samiullah; Chousalkar, K K; Roberts, J R; Sexton, M; May, D; Kiermeier, A

    2013-07-15

    The vast majority of eggs in Australia are washed prior to packing to remove dirt and fecal material and to reduce the microbial contamination of the egg shell. The egg contents can be an ideal growth medium for microorganisms which can result in human illness if eggs are stored improperly and eaten raw or undercooked, and it is estimated that egg-related salmonellosis is costing Australia $44 million per year. Egg shell characteristics such as shell thickness, amount of cuticle present, and thickness of individual egg shell layers can affect the ease with which bacteria can penetrate the egg shell and washing could partially or completely remove the cuticle layer. The current study was conducted to investigate the effects of egg washing on cuticle cover and effects of egg shell quality and cuticle cover on Salmonella Infantis penetration of the egg shell. A higher incidence of unfavorable ultrastructural variables of the mammillary layer such as late fusion, type B bodies, type A bodies, poor cap quality, alignment, depression, erosion and cubics were recorded in Salmonella penetrated areas of egg shells. The influence of egg washing on the ability of Salmonella Infantis on the egg shell surface to enter the egg internal contents was also investigated using culture-based agar egg penetration and real-time qPCR based experiments. The results from the current study indicate that washing affected cuticle cover. There were no significant differences in Salmonella Infantis penetration of washed or unwashed eggs. Egg shell translucency may have effects on Salmonella Infantis penetration of the egg shell. The qPCR assay was more sensitive for detection of Salmonella Infantis from egg shell wash and internal contents than traditional microbiological methods. The agar egg and whole egg inoculation experiments indicated that Salmonella Infantis penetrated the egg shells. Egg washing not only can be highly effective at removing Salmonella Infantis from the egg shell surface

  6. Controlling interface characteristics by adjusting core-shell structure

    International Nuclear Information System (INIS)

    Chang, H.Y.; Cheng, S.Y.; Sheu, C.I.

    2004-01-01

    Most grain boundary layer ceramics comprise semiconductive/conductive grains and insulated grain boundaries. Such a structure can be theoretically regarded as a shell (grain boundary layer) surrounds a core (conductive or semiconductive grain). The core-shell structure of titanium (Ti)-strontium titanate (ST) is composed of three zones - ST, non-stoichiometric strontium-titanium oxide and Ti, in order from shell to core. It was successfully prepared using a hydrothermal method. The Ti-ST core-shell structure was sintered in a reducing atmosphere and then annealed in air to achieve the metal-insulator-metal structure (MIM structure). The resulting MIM structure, annealed in air, changes with the oxygen stoichiometry of the ST shell (insulator layer) at various temperatures, which is thus used to tune its electrical characteristics. The characteristics exhibit nonlinear behavior. Accordingly, the thickness of the insulator layer can be adjusted in various annealing atmospheres and at various temperatures to develop various interfacial devices, such as varistors, capacitors and thermistors, without the use of complex donor/acceptor doping technology

  7. CO2 sequestration using principles of shell formation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Woo; Jang, Young-Nam [CO2 Sequestration Research Department, Korea Institute of Geoscience and Mineral Resources (Korea, Republic of); Lee, Si-Hyun; Lim, Kyoung-Soo; Jeong, Soon-Kwan [Energy Conservation Research Department of Clean Energy System Research Center, Korea Institute of Energy Research (Korea, Republic of)

    2011-06-15

    The biomimetic sequestration of carbon dioxide to reduce the CO2 emitted into the atmosphere is introduced in this paper. Bivalve shells are used as a good model of CO2 sequestration in this paper, because the shell is derived from the calcium ions and CO2 in seawater. Carbonic anhydrase, hemocyte from diseased shell (HDS) and extrapallial fluid (EFP) are involved in shell formation. This paper compares the soluble protein extracted from Crassostrea gigas with bovine carbonic anhydrase II in terms of their ability to promote CO2 hydration and the production of calcium precipitates. The result demonstrates that HDS has more functional groups to bind calcium ions in aqueous systems, and a different process of calcium precipitation, than does bovine carbonic anhydrase II. To understand molecular weight and secondary protein structure, mass-spectroscopic analysis (MALDI-TOF) and circular dichroism (CD) analysis were used. With regard to EPF, EPF related to shell formation is composed of several fractions and plays a role in sequestration of CO2.

  8. Double-shell tank system dangerous waste permit application

    International Nuclear Information System (INIS)

    1991-06-01

    This Double-Shell Tank System Dangerous Waste Permit Application should be read in conjunction with the 242-A Evaporator Dangerous Waste Permit Application and the Liquid Effluent Retention Facility Dangerous Waste Permit Application, also submitted on June 28, 1991. Information contained in the Double-Shell Tank System permit application is referenced in the other two permit applications. The Double-Shell Tank System stores and treats mixed waste received from a variety of sources on the Hanford Site. The 242-A Evaporator treats liquid mixed waste received from the double-shell tanks. The 242-A Evaporator returns a mixed-waste slurry to the double-shell tanks and generates the dilute mixed-waste stream stored in the Liquid Effluent Retention Facility. This report contains information on the following topics: Facility Description and General Provisions; Waste Characteristics; Process Information; Groundwater Monitoring; Procedures to Prevent Hazards; Contingency Plan; Personnel Training; Exposure Information Report; Waste Minimization Plan; Closure and Postclosure Requirements; Reporting and Recordkeeping; other Relevant Laws; and Certification. 150 refs., 141 figs., 118 tabs

  9. A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell.

    Science.gov (United States)

    Joyce, Walter G; Lucas, Spencer G; Scheyer, Torsten M; Heckert, Andrew B; Hunt, Adrian P

    2009-02-07

    A new, thin-shelled fossil from the Upper Triassic (Revueltian: Norian) Chinle Group of New Mexico, Chinlechelys tenertesta, is one of the most primitive known unambiguous members of the turtle stem lineage. The thin-shelled nature of the new turtle combined with its likely terrestrial habitat preference hint at taphonomic filters that basal turtles had to overcome before entering the fossil record. Chinlechelys tenertesta possesses neck spines formed by multiple osteoderms, indicating that the earliest known turtles were covered with rows of dermal armour. More importantly, the primitive, vertically oriented dorsal ribs of the new turtle are only poorly associated with the overlying costal bones, indicating that these two structures are independent ossifications in basal turtles. These novel observations lend support to the hypothesis that the turtle shell was originally a complex composite in which dermal armour fused with the endoskeletal ribs and vertebrae of an ancestral lineage instead of forming de novo. The critical shell elements (i.e. costals and neurals) are thus not simple outgrowths of the bone of the endoskeletal elements as has been hypothesized from some embryological observations.

  10. Shell effects in the nuclear deformation energy

    International Nuclear Information System (INIS)

    Ross, C.K.

    1973-01-01

    A new approach to shell effects in the Strutinsky method for calculating nuclear deformation energy is evaluated and the suggestion of non-conservation of angular momentum in the same method is resolved. Shell effects on the deformation energy in rotational bands of deformed nuclei are discussed. (B.F.G.)

  11. Hamiltonian treatment of the gravitational collapse of thin shells

    International Nuclear Information System (INIS)

    Crisostomo, Juan; Olea, Rodrigo

    2004-01-01

    A Hamiltonian treatment of the gravitational collapse of thin shells is presented. The direct integration of the canonical constraints reproduces the standard shell dynamics for a number of known cases. The formalism is applied in detail to three-dimensional spacetime and the properties of the (2+1)-dimensional charged black hole collapse are further elucidated. The procedure is also extended to deal with rotating solutions in three dimensions. The general form of the equations providing the shell dynamics implies the stability of black holes, as they cannot be converted into naked singularities by any shell collapse process

  12. Nuclear spectroscopy in large shell model spaces: recent advances

    International Nuclear Information System (INIS)

    Kota, V.K.B.

    1995-01-01

    Three different approaches are now available for carrying out nuclear spectroscopy studies in large shell model spaces and they are: (i) the conventional shell model diagonalization approach but taking into account new advances in computer technology; (ii) the recently introduced Monte Carlo method for the shell model; (iii) the spectral averaging theory, based on central limit theorems, in indefinitely large shell model spaces. The various principles, recent applications and possibilities of these three methods are described and the similarity between the Monte Carlo method and the spectral averaging theory is emphasized. (author). 28 refs., 1 fig., 5 tabs

  13. Gravitational collapse of a cylindrical null shell in vacuum

    Directory of Open Access Journals (Sweden)

    S. Khakshournia

    2008-03-01

    Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

  14. Stability analysis of thin-shell wormholes from charged black string

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, M.; Azam, M., E-mail: msharif.math@pu.edu.pk, E-mail: azammath@gmail.com [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan)

    2013-04-01

    In this paper, we construct thin-shell wormholes from charged black string through cut and paste procedure and investigate its stability. We assume modified generalized Chaplygin gas as a dark energy fluid (exotic matter) present in the thin layer of matter-shell. The stability of these constructed thin-shell wormholes is investigated in the scenario of linear perturbations. We conclude that static stable as well as unstable configurations are possible for cylindrical thin-shell wormholes.

  15. Sedimentological time-averaging and 14C dating of marine shells

    International Nuclear Information System (INIS)

    Fujiwara, Osamu; Kamataki, Takanobu; Masuda, Fujio

    2004-01-01

    The radiocarbon dating of sediments using marine shells involves uncertainties due to the mixed ages of the shells mainly attributed to depositional processes also known as 'sedimentological time-averaging'. This stratigraphic disorder can be removed by selecting the well-preserved indigenous shells based on ecological and taphonomic criteria. These criteria on sample selection are recommended for accurate estimation of the depositional age of geologic strata from 14 C dating of marine shells

  16. Shell-crossing in quasi-one-dimensional flow

    Science.gov (United States)

    Rampf, Cornelius; Frisch, Uriel

    2017-10-01

    Blow-up of solutions for the cosmological fluid equations, often dubbed shell-crossing or orbit crossing, denotes the breakdown of the single-stream regime of the cold-dark-matter fluid. At this instant, the velocity becomes multi-valued and the density singular. Shell-crossing is well understood in one dimension (1D), but not in higher dimensions. This paper is about quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence, the problem of the first shell-crossing, which is highly singular in Eulerian coordinates, has been desingularized by switching to Lagrangian coordinates, and can then be handled by perturbation theory. Here, all-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing, which is generically shown to be taking place earlier than for the unperturbed 1D flow. The time variable used for these statements is not the cosmic time t but the linear growth time τ ˜ t2/3. For simplicity, calculations are restricted to an Einstein-de Sitter universe in the Newtonian approximation, and tailored initial data are used. However it is straightforward to relax these limitations, if needed.

  17. Vibration experiment of the semi-spherical shell fixed in water; Suichu ni koteisareta hankyu shell no sessui shindo jikken

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, K; Yasuzawa, Y; Kagawa, K; Sugimoto, S [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1997-10-01

    Vibration characteristics of the semi-spherical shell fixed in water with bidirectional curvatures were studied experimentally. Various marine structures have been devised as relay station for life spaces or submarine resource excavation. As compared with land structures, marine structures are constantly under a severe condition subjected to hydrostatic pressure, and requires advanced technologies. The experimental result, numerical computation result by analytical code DASOR (Dynamic Analysis of Shell of Revolution) and theoretical analysis result were compared with each other. FEM and BEM were used in DASOR computation for the axisymmetric thin semi-spherical shell and circumferential liquid, respectively. Due to an added mass effect, the natural frequency decreased with an increase in water level regardless of mode orders. However, the water level over the top of the semi-spherical shell caused the nearly constant natural frequencies of 30-40% of that in the air. The computation result by DASOR well agreed with the experimental result demonstrating its validity. 4 refs., 13 figs., 1 tab.

  18. Multibody dynamic analysis using a rotation-free shell element with corotational frame

    Science.gov (United States)

    Shi, Jiabei; Liu, Zhuyong; Hong, Jiazhen

    2018-03-01

    Rotation-free shell formulation is a simple and effective method to model a shell with large deformation. Moreover, it can be compatible with the existing theories of finite element method. However, a rotation-free shell is seldom employed in multibody systems. Using a derivative of rigid body motion, an efficient nonlinear shell model is proposed based on the rotation-free shell element and corotational frame. The bending and membrane strains of the shell have been simplified by isolating deformational displacements from the detailed description of rigid body motion. The consistent stiffness matrix can be obtained easily in this form of shell model. To model the multibody system consisting of the presented shells, joint kinematic constraints including translational and rotational constraints are deduced in the context of geometric nonlinear rotation-free element. A simple node-to-surface contact discretization and penalty method are adopted for contacts between shells. A series of analyses for multibody system dynamics are presented to validate the proposed formulation. Furthermore, the deployment of a large scaled solar array is presented to verify the comprehensive performance of the nonlinear shell model.

  19. The NASA Monographs on Shell Stability Design Recommendations: A Review and Suggested Improvements

    Science.gov (United States)

    Nemeth, Michael P.; Starnes, James H., Jr.

    1998-01-01

    A summary of the existing NASA design criteria monographs for the design of buckling-resistant thin-shell structures is presented. Subsequent improvements in the analysis for nonlinear shell response are reviewed, and current issues in shell stability analysis are discussed. Examples of nonlinear shell responses that are not included in the existing shell design monographs are presented, and an approach for including reliability-based analysis procedures in the shell design process is discussed. Suggestions for conducting future shell experiments are presented, and proposed improvements to the NASA shell design criteria monographs are discussed.

  20. Core-shell magnetic nanowires fabrication and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kalska-Szostko, B., E-mail: kalska@uwb.edu.pl [Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok (Poland); Faculty of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Bialystok, Poland (Poland); Klekotka, U.; Satuła, D. [Institute of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok (Poland); Faculty of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Bialystok, Poland (Poland)

    2017-02-28

    Highlights: • New approach for nanowires modification are presented. • Physical and chemical characterization of the nanowires are shown. • Properties modulations as an effect of the surface layer composition are discussed. - Abstract: In this paper, a new way of the preparation of core-shell magnetic nanowires has been proposed. For the modification Fe nanowires were prepared by electrodeposition in anodic aluminium oxide matrixes, in first step. In second, by wetting chemical deposition, shell layers of Ag, Au or Cu were obtained. Resultant core-shell nanowires structure was characterized by X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray. Whereas magnetic properties by Mössbauer spectroscopy.

  1. Atomic mass formula with linear shell terms

    International Nuclear Information System (INIS)

    Uno, Masahiro; Yamada, Masami; Ando, Yoshihira; Tachibana, Takahiro.

    1981-01-01

    An atomic mass formula is constructed in the form of a sum of gross terms and empirical linear shell terms. Values of the shell parameters are determined after the statistical method of Uno and Yamada, Which is characterized by inclusion of the error inherent in the mass formula. The resulting formula reproduces the input masses with the standard deviation of 393 keV. A prescription is given for estimating errors of calculated masses. The mass formula is compared with recent experimental data of Rb, Cs and Fr isotopes, which are not included in the input data, and also with the constant-shell-term formula of Uno and Yamada. (author)

  2. Double shell tank waste analysis plan

    International Nuclear Information System (INIS)

    Mulkey, C.H.; Jones, J.M.

    1994-01-01

    Waste analysis plan for the double shell tanks. SD-WM-EV-053 is Superseding SD-WM-EV-057.This document provides the plan for obtaining information needed for the safe waste handling and storage of waste in the Double Shell Tank Systems. In Particular it addresses analysis necessary to manage waste according to Washington Administrative Code 173-303 and Title 40, parts 264 and 265 of the Code of Federal Regulations

  3. On the shell model connection of the cluster model

    International Nuclear Information System (INIS)

    Cseh, J.; Levai, G.; Kato, K.

    2000-01-01

    Complete text of publication follows. The interrelation of basic nuclear structure models is a longstanding problem. The connection between the spherical shell model and the quadrupole collective model has been studied extensively, and symmetry considerations proved to be especially useful in this respect. A collective band was interpreted in the shell model language long ago as a set of states (of the valence nucleons) with a specific SU(3) symmetry. Furthermore, the energies of these rotational states are obtained to a good approximation as eigenvalues of an SU(3) dynamically symmetric shell model Hamiltonian. On the other hand the relation of the shell model and cluster model is less well explored. The connection of the harmonic oscillator (i.e. SU(3)) bases of the two approaches is known, but it was established only for the unrealistic harmonic oscillator interactions. Here we investigate the question: Can an SU(3) dynamically symmetric interaction provide a similar connection between the spherical shell model and the cluster model, like the one between the shell and collective models? In other words: whether or not the energy of the states of the cluster bands, defined by a specific SU(3) symmetries, can be obtained from a shell model Hamiltonian (with SU(3) dynamical symmetry). We carried out calculations within the framework of the semimicroscopic algebraic cluster model, in which not only the cluster model space is obtained from the full shell model space by an SU(3) symmetry-dictated truncation, but SU(3) dynamically symmetric interactions are also applied. Actually, Hamiltonians of this kind proved to be successful in describing the gross features of cluster states in a wide energy range. The novel feature of the present work is that we apply exclusively shell model interactions. The energies obtained from such a Hamiltonian for several bands of the ( 12 C, 14 C, 16 O, 20 Ne, 40 Ca) + α systems turn out to be in good agreement with the experimental

  4. Perturbation theory instead of large scale shell model calculations

    International Nuclear Information System (INIS)

    Feldmeier, H.; Mankos, P.

    1977-01-01

    Results of large scale shell model calculations for (sd)-shell nuclei are compared with a perturbation theory provides an excellent approximation when the SU(3)-basis is used as a starting point. The results indicate that perturbation theory treatment in an SU(3)-basis including 2hω excitations should be preferable to a full diagonalization within the (sd)-shell. (orig.) [de

  5. CIRCUMSTELLAR SHELLS IN ABSORPTION IN TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Borkowski, Kazimierz J.; Blondin, John M.; Reynolds, Stephen P.

    2009-01-01

    Progenitors of Type Ia supernovae (SNe) have been predicted to modify their ambient circumstellar (CSM) and interstellar environments through the action of their powerful winds. While there is X-ray and optical evidence for circumstellar interaction in several remnants of Type Ia SNe, widespread evidence for such interaction in Type Ia SNe themselves has been lacking. We consider prospects for the detection of CSM shells that have been predicted to be common around Type Ia SNe. Such shells are most easily detected in Na I absorption lines. Variable (declining) absorption is expected to occur soon after the explosion, primarily during the SN rise time, for shells located within ∼1-10 pc of a SN. The distance of the shell from the SN can be determined by measuring the timescale for line variability.

  6. Thick or Thin Ice Shell on Europa?

    Science.gov (United States)

    2007-01-01

    Scientists are all but certain that Europa has an ocean underneath its icy surface, but they do not know how thick this ice might be. This artist concept illustrates two possible cut-away views through Europa's ice shell. In both, heat escapes, possibly volcanically, from Europa's rocky mantle and is carried upward by buoyant oceanic currents. If the heat from below is intense and the ice shell is thin enough (left), the ice shell can directly melt, causing what are called 'chaos' on Europa, regions of what appear to be broken, rotated and tilted ice blocks. On the other hand, if the ice shell is sufficiently thick (right), the less intense interior heat will be transferred to the warmer ice at the bottom of the shell, and additional heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise, flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the extremely cold, brittle ice at the surface. Europa is no larger than Earth's moon, and its internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As tides raised by Jupiter in Europa's ocean rise and fall, they may cause cracking, additional heating and even venting of water vapor into the airless sky above Europa's icy surface. (Artwork by Michael Carroll.)

  7. Pair of null gravitating shells: III. Algebra of Dirac's observables

    International Nuclear Information System (INIS)

    Kouletsis, I; Hajicek, P

    2002-01-01

    The study of the two-shell system started in 'pair of null gravitating shells I and II' is continued. The pull back of the Liouville form to the constraint surface, which contains complete information about the Poisson brackets of Dirac observables, is computed in the singular double-null Eddington-Finkelstein (DNEF) gauge. The resulting formula shows that the variables conjugate to the Schwarzschild masses of the intershell spacetimes are simple combinations of the values of the DNEF coordinates on these spacetimes at the shells. The formula is valid for any number of in- and outgoing shells. After applying it to the two-shell system, the symplectic form is calculated for each component of the physical phase space; regular coordinates are found, defining it as a symplectic manifold. The symplectic transformation between the initial and final values of observables for the shell-crossing case is given

  8. Workability and Compressive Strength for Concrete With Coconut Shell Aggregate

    Directory of Open Access Journals (Sweden)

    Leman Alif Syazani

    2017-01-01

    Full Text Available This study was conducted to investigate the compressive strength and workability of concrete added with coconut shells. Comparisons were made between conventional concrete with concrete mix coconut shell. In this study, the concretes were mixes with coconut shell by percentage of weight concrete which is 0%, 5%, and 10%. The coconut shell has been crushed first, then it was sieved, to get the optimum size which, that retained on the 5mm sieve and passing 10mm sieve. Experimental tests conducted in this study are slump test and compressive test. The results from this study are workability of concrete added with 0% and 5% of coconut shell has medium degree of workability compared to concrete added with 10% that has low workability. For the compressive strength, the concrete added with 5% and 10% of coconut shell has lower strength compared with normal concrete.

  9. Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells

    OpenAIRE

    Dolan, Laurie; Matulka, Ray; Worn, Jeffrey; Nizio, John

    2015-01-01

    Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control), 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermitt...

  10. Effects of alga polysaccharide capsule shells on in-vivo bioavailability and disintegration

    Science.gov (United States)

    Li, Ting; Guo, Shuju; Ma, Lin; Yuan, Yi; Han, Lijun

    2012-01-01

    Gelatin has been used in hard capsule shells for more than a century, and some shortcomings have appeared, such as high moisture content and risk of transmitting diseases of animal origin to people. Based on available studies regarding gelatin and vegetable shells, we developed a new type of algal polysaccharide capsule (APPC) shells. To test whether our products can replace commercial gelatin shells, we measured in-vivo plasma concentration of 12 selected volunteers with a model drug, ibuprofen, using high performance liquid chromatography (HPLC), by calculating the relative bioavailability of APPC and Qualicaps® referenced to gelatin capsules and assessing bioequivalence of the three types of shells, and calculated pharmacokinetic parameters with the software DAS 2.0 (China). The results show that APPC shells possess bioequivalence with Qualicaps® and gelatin shells. Moreover, the disintegration behavior of four types of shells (APPC, Vegcaps®, Qualicaps® and gelatin shells) with the content of lactose and radioactive element (99mTc) was observed via gamma-scintigraphic images. The bioavailability and gamma-scintigraphic studies showed that APPC was not statistically different from other vegetable and gelatin capsule shells with respect to in-vivo behavior. Hence, it can be concluded that APPCs are exchangeable with other vegetable and gelatin shells.

  11. Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nonkumwong, Jeeranan [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Pakawanit, Phakkhananan [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wipatanawin, Angkana [Division of Biochemistry and Biochemical Technology, Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Jantaratana, Pongsakorn [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 11900 (Thailand); Ananta, Supon [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Srisombat, Laongnuan, E-mail: slaongnuan@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2016-04-01

    In this work, the core-magnesium ferrite (MgFe{sub 2}O{sub 4}) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe{sub 2}O{sub 4} nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe{sub 2}O{sub 4} core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV–visible spectroscopy (UV–vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe{sub 2}O{sub 4} core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV–vis spectra of complete coated MgFe{sub 2}O{sub 4}-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe{sub 2}O{sub 4}-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe{sub 2}O{sub 4} core. Both of MgFe{sub 2}O{sub 4} and MgFe{sub 2}O{sub 4}-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line. - Highlights: • Synthesis of MgFe{sub 2}O{sub 4}-Au core-shell nanoparticles with particle size < 100 nm • Complete Au shell coating on the surfaces of MgFe{sub 2}O{sub 4} nanoparticles • In vitro cytotoxicity study of complete coated MgFe{sub 2}O{sub 4}-Au core-shell

  12. Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles

    International Nuclear Information System (INIS)

    Nonkumwong, Jeeranan; Pakawanit, Phakkhananan; Wipatanawin, Angkana; Jantaratana, Pongsakorn; Ananta, Supon; Srisombat, Laongnuan

    2016-01-01

    In this work, the core-magnesium ferrite (MgFe_2O_4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe_2O_4 nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe_2O_4 core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV–visible spectroscopy (UV–vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe_2O_4 core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV–vis spectra of complete coated MgFe_2O_4-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe_2O_4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe_2O_4 core. Both of MgFe_2O_4 and MgFe_2O_4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line. - Highlights: • Synthesis of MgFe_2O_4-Au core-shell nanoparticles with particle size < 100 nm • Complete Au shell coating on the surfaces of MgFe_2O_4 nanoparticles • In vitro cytotoxicity study of complete coated MgFe_2O_4-Au core-shell nanoparticles

  13. Charge symmetry of the nuclear force as off-shell constraint

    International Nuclear Information System (INIS)

    Sauer, P.U.

    1975-01-01

    Off-shell changes are generated in the 1 S 0 nucleon-nucleon interaction using the Reid soft-core potential and unitary transformations of short range. Charge symmetry is assumed for the nuclear force. The same off-shell variations of the Reid potential are employed as the hadronic part of the proton-proton interaction and as neutron-neutron interaction. The Reid potential fits the experimental proton-proton data. It also accounts for the neutron-neutron scattering length with satisfying accuracy. The off-shell behavior of the Reid potential is varied in two different ways. First, off-shell changes consistent with the experimental proton-proton data can be selected. (auth) are performed which preserve the fit to the proton-proton data. Most transformed potentials of the type attempted here are unable to yield the correct experimental value of the neutron-neutron scattering length and have to be rejected. A simple practical rule is given according to which the off-shell changes consistent with the neutron-neutron scattering length can be selected. Second, off-shell changes are performed which leave the neutron-neutron scattering length unaltered. Transformed potentials of this type have usually been employed in nuclear-structure calculations. The potentials which exhibit large off-shell effects in nuclear structure are unable to account for the experimental proton-proton data. Their off-shell effects are therefore of no physical significance, and the potentials have to be rejected. A simple practical rule is given according to which the off-shell changes consistent with the experimental proton-proton data can be selected. (U.S.)

  14. Intershell correlations in photoionization of outer shells

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Ya. [The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Chernysheva, L.V. [A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Drukarev, E.G. [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute, St. Petersburg 188300 (Russian Federation)

    2016-02-15

    We demonstrate that the cross sections for photoionization of the outer shells are noticeably modified at the photon energies close to the thresholds of ionization of the inner shells due to correlations with the latter. The correlations may lead to increase or to decrease of the cross sections just above the ionization thresholds.

  15. Intershell correlations in photoionization of outer shells

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Chernysheva, L.V.; Drukarev, E.G.

    2016-01-01

    We demonstrate that the cross sections for photoionization of the outer shells are noticeably modified at the photon energies close to the thresholds of ionization of the inner shells due to correlations with the latter. The correlations may lead to increase or to decrease of the cross sections just above the ionization thresholds.

  16. The theory of spherically symmetric thin shells in conformal gravity

    Science.gov (United States)

    Berezin, Victor; Dokuchaev, Vyacheslav; Eroshenko, Yury

    The spherically symmetric thin shells are the nearest generalizations of the point-like particles. Moreover, they serve as the simple sources of the gravitational fields both in General Relativity and much more complex quadratic gravity theories. We are interested in the special and physically important case when all the quadratic in curvature tensor (Riemann tensor) and its contractions (Ricci tensor and scalar curvature) terms are present in the form of the square of Weyl tensor. By definition, the energy-momentum tensor of the thin shell is proportional to Diracs delta-function. We constructed the theory of the spherically symmetric thin shells for three types of gravitational theories with the shell: (1) General Relativity; (2) Pure conformal (Weyl) gravity where the gravitational part of the total Lagrangian is just the square of the Weyl tensor; (3) Weyl-Einstein gravity. The results are compared with these in General Relativity (Israel equations). We considered in detail the shells immersed in the vacuum. Some peculiar properties of such shells are found. In particular, for the traceless ( = massless) shell, it is shown that their dynamics cannot be derived from the matching conditions and, thus, is completely arbitrary. On the contrary, in the case of the Weyl-Einstein gravity, the trajectory of the same type of shell is completely restored even without knowledge of the outside solution.

  17. Dynamics of Inhomogeneous Shell Systems Under Non-Stationary Loading (Survey)

    Science.gov (United States)

    Lugovoi, P. Z.; Meish, V. F.

    2017-09-01

    Experimental works on the determination of dynamics of smooth and stiffened cylindrical shells contacting with a soil medium under various non-stationary loading are reviewed. The results of studying three-layer shells of revolution whose motion equations are obtained within the framework of the hypotheses of the Timoshenko geometrically nonlinear theory are stated. The numerical results for shells with a piecewise or discrete filler enable the analysis of estimation of the influence of geometrical and physical-mechanical parameters of structures on their dynamics and reveal new mechanical effects. Basing on the classical theory of shells and rods, the effect of the discrete arrangement of ribs and coefficients of the Winkler or Pasternak elastic foundation on the normal frequencies and modes of rectangular planar cylindrical and spherical shells is studied. The number and shape of dispersion curves for longitudinal harmonic waves in a stiffened cylindrical shell are determined. The equations of vibrations of ribbed shells of revolution on Winkler or Pasternak elastic foundation are obtained using the geometrically nonlinear theory and the Timoshenko hypotheses. On applying the integral-interpolational method, numerical algorithms are developed and the corresponding non-stationary problems are solved. The special attention is paid to the statement and solution of coupled problems on the dynamical interaction of cylindrical or spherical shells with the soil water-saturated medium of different structure.

  18. Shell biofilm-associated nitrous oxide production in marine molluscs

    DEFF Research Database (Denmark)

    Heisterkamp, I.M.; Schramm, Andreas; Larsen, Lone Heimann

    2013-01-01

    Emission of the greenhouse gas nitrous oxide (N2O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces...... are important sites of N2O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2O emission. Nitrification and denitrification were equally important sources of N2O in shell biofilms as revealed by 15N-stable isotope...... mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2O production of the shell biofilm. This animal-induced stimulation...

  19. Low-energy impact of adaptive cylindrical piezoelectric-composite shells

    Energy Technology Data Exchange (ETDEWEB)

    Saravanos, D.A. [University of Patras (United Kingdom). Dept. of Mechanical Engineering and Aeronautics; Christoforou, A.P. [Kuwait Univ. (Kuwait). Dept. of Mechanical Engineering

    2002-04-01

    A theoretical framework for analyzing low-energy impacts of laminated shells with active and sensory piezoelectric layers is presented, including impactor dynamics and contact law. The formulation encompasses a coupled piezoelectric shell theory mixing first order shear displacement assumptions and layerwise variation of electric potential. An exact in-plane Ritz solution for the impact of open cylindrical piezoelectric-composite shells is developed and solved numerically using an explicit time integration scheme. The active impact control problem of adaptive cylindrical shells with distributed curved piezoelectric actuators is addressed. The cases of optimized state feedback controllers and output feedback controllers using piezoelectric sensors are analyzed. Numerical results quantify the impact response of cylindrical shells of various curvatures including the signal of curved piezoelectric sensors. Additional numerical studies quantify the impact response of adaptive cylindrical panels and investigate the feasibility of actively reducing the impact force. (author)

  20. Hanford double shell tank corrosion monitoring instrument tree prototype

    International Nuclear Information System (INIS)

    Nelson, J.L.; Edgemon, G.L.; Ohl, P.C.

    1995-11-01

    High-level nuclear wastes at the Hanford site are stored underground in carbon steel double-shell and single-shell tanks (DSTs and SSTs). The installation of a prototype corrosion monitoring instrument tree into DST 241-A-101 was completed in December 1995. The instrument tree has the ability to detect and discriminate between uniform corrosion, pitting, and stress corrosion cracking (SCC) through the use of electrochemical noise measurements and a unique stressed element, three-electrode probe. The tree itself is constructed of AISI 304L stainless steel (UNS S30403), with probes in the vapor space, vapor/liquid interface and liquid. Successful development of these trees will allow their application to single shell tanks and the transfer of technology to other US Department of Energy (DOE) sites. Keywords: Hanford, radioactive waste, high-level waste tanks, electrochemical noise, probes, double-shell tanks, single-shell tanks, corrosion

  1. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    International Nuclear Information System (INIS)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-01-01

    Double-shelled sea urchin-like yolk-shell Fe 3 O 4 /TiO 2 /Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe 3 O 4 /TiO 2 support by a in situ reduction of HAuCl 4 with NaBH 4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO 2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe 3 O 4 /TiO 2 microspheres. The sea urchin-like structure composed of TiO 2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe 3 O 4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe 3 O 4 /TiO 2 /Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min −1 and turnover frequency is 5457 h −1 . (paper)

  2. Modeling of microencapsulated polymer shell solidification

    International Nuclear Information System (INIS)

    Boone, T.; Cheung, L.; Nelson, D.; Soane, D.; Wilemski, G.; Cook, R.

    1995-01-01

    A finite element transport model has been developed and implemented to complement experimental efforts to improve the quality of ICF target shells produced via controlled-mass microencapsulation. The model provides an efficient means to explore the effect of processing variables on the dynamics of shell dimensions, concentricity, and phase behavior. Comparisons with experiments showed that the model successfully predicts the evolution of wall thinning and core/wall density differences. The model was used to efficiently explore and identify initial wall compositions and processing temperatures which resulted in concentricity improvements from 65 to 99%. The evolution of trace amounts of water entering into the shell wall was also tracked in the simulations. Comparisons with phase envelope estimations from modified UNIFAP calculations suggest that the water content trajectory approaches the two-phase region where vacuole formation via microphase separation may occur

  3. Novel fluorescent core-shell nanocontainers for cell membrane transport.

    Science.gov (United States)

    Yin, Meizhen; Kuhlmann, Christoph R W; Sorokina, Ksenia; Li, Chen; Mihov, George; Pietrowski, Eweline; Koynov, Kaloian; Klapper, Markus; Luhmann, Heiko J; Müllen, Klaus; Weil, Tanja

    2008-05-01

    The synthesis and characterization of novel core-shell macromolecules consisting of a fluorescent perylene-3,4,9,10-tetracarboxdiimide chromophore in the center surrounded by a hydrophobic polyphenylene shell as a first and a flexible hydrophilic polymer shell as a second layer was presented. Following this strategy, several macromolecules bearing varying polymer chain lengths, different polymer shell densities, and increasing numbers of positive and negative charges were achieved. Because all of these macromolecules reveal a good water solubility, their ability to cross cellular membranes was investigated. In this way, a qualitative relationship between the molecular architecture of these macromolecules and the biological response was established.

  4. Design and Analysis of Tow-Steered Composite Shells Using Fiber Placement

    Science.gov (United States)

    Wu, K. Chauncey

    2008-01-01

    In this study, a sub-scale advanced composite shell design is evaluated to determine its potential for use on a future aircraft fuselage. Two composite shells with the same nominal 8-ply [+/-45/+/-Theta](sub s) layup are evaluated, where Theta indicates a tow-steered ply. To build this shell, a fiber placement machine would be used to steer unidirectional prepreg tows as they are placed around the circumference of a 17-inch diameter right circular cylinder. The fiber orientation angle varies continuously from 10 degrees (with respect to the shell axis of revolution) at the crown, to 45 degrees on the side, and back to 10 degrees on the keel. All 24 tows are placed at each point on every fiber path in one structure designated as the shell with overlaps. The resulting pattern of tow overlaps causes the laminate thickness to vary between 8 and 16 plies. The second shell without tow overlaps uses the capability of the fiber placement machine to cut and add tows at any point along the fiber paths to fabricate a shell with a nearly uniform 8-ply laminate thickness. Issues encountered during the design and analysis of these shells are presented and discussed. Static stiffness and buckling loads of shells with tow-steered layups are compared with the performance of a baseline quasi-isotropic shell using both finite element analyses and classical strength of materials theory.

  5. Simple proteomics data analysis in the object-oriented PowerShell.

    Science.gov (United States)

    Mohammed, Yassene; Palmblad, Magnus

    2013-01-01

    Scripting languages such as Perl and Python are appreciated for solving simple, everyday tasks in bioinformatics. A more recent, object-oriented command shell and scripting language, Windows PowerShell, has many attractive features: an object-oriented interactive command line, fluent navigation and manipulation of XML files, ability to consume Web services from the command line, consistent syntax and grammar, rich regular expressions, and advanced output formatting. The key difference between classical command shells and scripting languages, such as bash, and object-oriented ones, such as PowerShell, is that in the latter the result of a command is a structured object with inherited properties and methods rather than a simple stream of characters. Conveniently, PowerShell is included in all new releases of Microsoft Windows and therefore already installed on most computers in classrooms and teaching labs. In this chapter we demonstrate how PowerShell in particular allows easy interaction with mass spectrometry data in XML formats, connection to Web services for tools such as BLAST, and presentation of results as formatted text or graphics. These features make PowerShell much more than "yet another scripting language."

  6. Generalized synthesis of mesoporous shells on zeolite crystals

    KAUST Repository

    Han, Yu; Pitukmanorom, Pemakorn; Zhao, L. J.; Ying, Jackie

    2010-01-01

    A simple and generalized synthetic approach is developed for creating mesoporous shells on zeolite crystals. This method allows for the tailoring of thickness, pore size, and composition of the mesoporous shell, and can be applied to zeolites

  7. Structural Acoustic Physics Based Modeling of Curved Composite Shells

    Science.gov (United States)

    2017-09-19

    NUWC-NPT Technical Report 12,236 19 September 2017 Structural Acoustic Physics -Based Modeling of Curved Composite Shells Rachel E. Hesse...SUBTITLE Structural Acoustic Physics -Based Modeling of Curved Composite Shells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...study was to use physics -based modeling (PBM) to investigate wave propagations through curved shells that are subjected to acoustic excitation. An

  8. Study of thiophene inner shell photofragmentation

    International Nuclear Information System (INIS)

    Mundim, M.S.P.; Mocellin, A.; Makiuchi, N.; Naves de Brito, A.; Attie, M.; Correia, N.

    2007-01-01

    We investigated the inner shell photofragmentation of thiophene by time of flight (TOF) mass spectroscopy using multi-coincidence electron-ion techniques. Our main purpose was to understand aspects of molecular relaxation process after inner shell excitation and to search for bond break selectivity. Analyses of mass and branching ratios are presented and the results suggest different mechanisms and channel of fragmentation when compared with S 2p and C 1s excitations

  9. Study of thiophene inner shell photofragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Mundim, M.S.P. [Instituto de Fisica, Universidade de Brasilia-UnB, P.O. Box 04455, CEP 70919-970 Brasilia, DF (Brazil)], E-mail: spedrosa@fis.unb.br; Mocellin, A.; Makiuchi, N. [Instituto de Fisica, Universidade de Brasilia-UnB, P.O. Box 04455, CEP 70919-970 Brasilia, DF (Brazil); Naves de Brito, A. [Instituto de Fisica, Universidade de Brasilia-UnB, P.O. Box 04455, CEP 70919-970 Brasilia, DF (Brazil); Laboratorio Nacional de Luz Sincrotron-LNLS, P.O. Box 6192, CEP 13084-971 Campinas, SP (Brazil); Attie, M. [Departamento de Ciencias Biologicas, Universidade Estadual de Santa Cruz, UESC Rodovia Ilheus-Itabuna, km 16, CEP 45 650 000 Ilheus, BA (Brazil); Correia, N. [Departamento de Ciencias Exatas e Tecnologicas, Universidade Estadual de Santa Cruz, UESC, Rodovia Ilheus-Itabuna, km 16, CEP 45 650 000 Ilheus, BA (Brazil); Departament of Quantum Chemistry, University of Uppsala, P.O. Box 518, 751 21 Uppsala (Sweden)

    2007-03-15

    We investigated the inner shell photofragmentation of thiophene by time of flight (TOF) mass spectroscopy using multi-coincidence electron-ion techniques. Our main purpose was to understand aspects of molecular relaxation process after inner shell excitation and to search for bond break selectivity. Analyses of mass and branching ratios are presented and the results suggest different mechanisms and channel of fragmentation when compared with S 2p and C 1s excitations.

  10. On the shell-model-connection of the cluster model

    International Nuclear Information System (INIS)

    Cseh, J.

    2000-01-01

    Complete text of publication follows. The interrelation of basic nuclear structure models is a longstanding problem. The connection between the spherical shell model and the quadrupole collective model has been studied extensively, and symmetry considerations proved to be especially useful in this respect. A collective band was interpreted in the shell model language long ago [1] as a set of states (of the valence nucleons) with a specific SU(3) symmetry. Furthermore, the energies of these rotational states are obtained to a good approximation as eigenvalues of an SU(3) dynamically symmetric shell model Hamiltonian. On the other hand the relation of the shell model and cluster model is less well explored. The connection of the harmonic oscillator (i.e. SU(3)) bases of the two approaches is known [2] but it was established only for the unrealistic harmonic oscillator interactions. Here we investigate the question: Can an SU(3) dynamically symmetric interaction provide a similar connection between the spherical shell model and the cluster model, like the one between the shell and collective models? In other words: whether or not the energy of the states of the cluster bands, defined by a specific SU(3) symmetries, can be obtained from a shell model Hamiltonian (with SU(3) dynamical symmetry). We carried out calculations within the framework of the semimicroscopic algebraic cluster model [3,4] in order to find an answer to this question, which seems to be affirmative. In particular, the energies obtained from such a Hamiltonian for several bands of the ( 12 C, 14 C, 16 O, 20 Ne, 40 Ca) + α systems turn out to be in good agreement with the experimental values. The present results show that the simple and transparent SU(3) connection between the spherical shell model and the cluster model is valid not only for the harmonic oscillator interactions, but for much more general (SU(3) dynamically symmetric) Hamiltonians as well, which result in realistic energy spectra. Via

  11. Elasto-plastic impact of hemispherical shell impacting on hard rigid sphere

    Science.gov (United States)

    Raftopoulos, D. D.; Spicer, A. L.

    1976-01-01

    An analysis of plastic stress waves for cylindrical metallic projectile in impact is extended to an analysis of a hemispherical shell suffereing plastic deformation during the process of impact. It is assumed that the hemispherical shell with a prescribed launch velocity impinges a fixed rigid sphere of diameter equal to the internal diameter of the shell. The dynamic biaxial state of stress present in the shell during deformation is investigated. The analysis is valuable for studying the state of stress during large plastic deformation of a hemispherical shell.

  12. An IBM-3 hamiltonian from a multi-j-shell model

    International Nuclear Information System (INIS)

    Evans, J.A.; Elliott, J.P.; Lac, V.S.; Long, G.L.

    1995-01-01

    The number and isospin dependence of the hamiltonian in the isospin invariant form (IBM-3) of the boson model is deduced from a seniority mapping onto a shell-model system of several shells. The numerical results are compared with earlier work for a single j-shell. (orig.)

  13. Current directions in core-shell nanoparticle design

    Science.gov (United States)

    Schärtl, Wolfgang

    2010-06-01

    Ten years ago I wrote a review about the important field of core-shell nanoparticles, focussing mainly on our own work about tracer systems, and briefly addressing polymer-coated nanoparticles as fillers for homogeneous polymer-colloid composites. Since then, the potential use of core-shell nanoparticles as multifunctional sensors or potential smart drug-delivery vehicles in biology and medicine has gained more and more importance, affording special types of multi-functionalized and bio-compatible nanoparticles. In this new review article, I try to address the most important developments during the last ten years. This overview is mainly based on frequently cited and more specialized recent review articles from leaders in their respective field. We will consider a variety of nanoscopic core-shell architectures from highly fluorescent nanoparticles (NPs), protected magnetic NPs, multifunctional NPs, thermoresponsive NPs and biocompatible systems to, finally, smart drug-delivery systems.Ten years ago I wrote a review about the important field of core-shell nanoparticles, focussing mainly on our own work about tracer systems, and briefly addressing polymer-coated nanoparticles as fillers for homogeneous polymer-colloid composites. Since then, the potential use of core-shell nanoparticles as multifunctional sensors or potential smart drug-delivery vehicles in biology and medicine has gained more and more importance, affording special types of multi-functionalized and bio-compatible nanoparticles. In this new review article, I try to address the most important developments during the last ten years. This overview is mainly based on frequently cited and more specialized recent review articles from leaders in their respective field. We will consider a variety of nanoscopic core-shell architectures from highly fluorescent nanoparticles (NPs), protected magnetic NPs, multifunctional NPs, thermoresponsive NPs and biocompatible systems to, finally, smart drug-delivery systems

  14. Atomic inner-shell physics

    International Nuclear Information System (INIS)

    Crasemann, B.

    1985-01-01

    This book discusses: relativistic and quantum electrodynamic effects on atomic inner shells; relativistic calculation of atomic transition probabilities; many-body effects in energetic atomic transitions; Auger Electron spectrometry of core levels of atoms; experimental evaluation of inner-vacancy level energies for comparison with theory; mechanisms for energy shifts of atomic K-X rays; atomic physics research with synchrotron radiation; investigations of inner-shell states by the electron energy-loss technique at high resolution; coherence effects in electron emission by atoms; inelastic X-ray scattering including resonance phenomena; Rayleigh scattering: elastic photon scattering by bound electrons; electron-atom bremsstrahlung; X-ray and bremsstrahlung production in nuclear reactions; positron production in heavy-ion collisions, and X-ray processes in heavy-ion collisions

  15. Optical absorption of carbon-gold core-shell nanoparticles

    Science.gov (United States)

    Wang, Zhaolong; Quan, Xiaojun; Zhang, Zhuomin; Cheng, Ping

    2018-01-01

    In order to enhance the solar thermal energy conversion efficiency, we propose to use carbon-gold core-shell nanoparticles dispersed in liquid water. This work demonstrates theoretically that an absorbing carbon (C) core enclosed in a plasmonic gold (Au) nanoshell can enhance the absorption peak while broadening the absorption band; giving rise to a much higher solar absorption than most previously studied core-shell combinations. The exact Mie solution is used to evaluate the absorption efficiency factor of spherical nanoparticles in the wavelength region from 300 nm to 1100 nm as well as the electric field and power dissipation profiles inside the nanoparticles at specified wavelengths (mostly at the localized surface plasmon resonance wavelength). The field enhancement by the localized plasmons at the gold surfaces boosts the absorption of the carbon particle, resulting in a redshift of the absorption peak with increased peak height and bandwidth. In addition to spherical nanoparticles, we use the finite-difference time-domain method to calculate the absorption of cubic core-shell nanoparticles. Even stronger enhancement can be achieved with cubic C-Au core-shell structures due to the localized plasmonic resonances at the sharp edges of the Au shell. The solar absorption efficiency factor can exceed 1.5 in the spherical case and reach 2.3 in the cubic case with a shell thickness of 10 nm. Such broadband absorption enhancement is in great demand for solar thermal applications including steam generation.

  16. Yolk@Shell Nanoarchitectures with Bimetallic Nanocores-Synthesis and Electrocatalytic Applications.

    Science.gov (United States)

    Guiet, Amandine; Unmüssig, Tobias; Göbel, Caren; Vainio, Ulla; Wollgarten, Markus; Driess, Matthias; Schlaad, Helmut; Polte, Jörg; Fischer, Anna

    2016-10-10

    In the present paper, we demonstrate a versatile approach for the one-pot synthesis of metal oxide yolk@shell nanostructures filled with bimetallic nanocores. This novel approach is based on the principles of hydrophobic nanoreactor soft-templating and is exemplified for the synthesis of various AgAu NP @tin-rich ITO (AgAu@ITO TR ) yolk@shell nanomaterials. Hydrophobic nanoreactor soft-templating thereby takes advantage of polystyrene-block-poly(4-vinylpiridine) inverse micelles as two-compartment nanoreactor template, in which the core and the shell of the micelles serve as metal and metal oxide precursor reservoir, respectively. The composition, size and number of AuAg bimetallic nanoparticles incorporated within the ITO TR yolk@shell can easily be tuned. The conductivity of the ITO TR shell and the bimetallic composition of the AuAg nanoparticles, the as-synthesized AuAg NP @ITO TR yolk@shell materials could be used as efficient electrocatalysts for electrochemical glucose oxidation with improved onset potential when compared to their gold counterpart.

  17. Shell shape as a biomarker of marine pollution historic increase.

    Science.gov (United States)

    Márquez, F; Primost, M A; Bigatti, G

    2017-01-30

    Buccinanops globulosus is a TBT sensitive marine gastropod, classified as a good indicator of imposex incidence and used as a model to study adverse contamination effects. Population and maritime industries has incremented pollution in Nuevo gulf harbor since 1970s, promoting morphological changes in B. globulosus shell shape. We study the shell shape of the species comparing present day's specimens from the harbor zone with those collected in the same zone before the increasing of maritime activity and pre-Hispanic archaeological Middens. We demonstrated that harbor pollution produces globular shell shape in B. globulosus, an effect that probably allows gastropods to isolate themselves from the external adverse environment. On the contrary, shells from pre-Hispanic periods, unpolluted sites and those collected before the expansion of maritime activities, presented an elongated shell shape. Our study confirms that shell shape variation in marine gastropods can be used as a biomarker of harbor pollution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Collapsing shells and black holes: a quantum analysis

    Science.gov (United States)

    Leal, P.; Bernardini, A. E.; Bertolami, O.

    2018-06-01

    The quantization of a spherically symmetric null shells is performed and extended to the framework of phase-space noncommutative (NC) quantum mechanics. This shell is considered to be inside a black hole event horizon. The encountered properties are investigated making use of the Israel junction conditions on the shell, considering that it is the boundary between two spherically symmetric spacetimes. Using this method, and considering two different Kantowski–Sachs spacetimes as a representation for the Schwarzschild spacetime, the relevant quantities on the shell are computed, such as its stress-energy tensor and the action for the whole spacetime. From the obtained action, the Wheeler–deWitt equation is deduced in order to provide the quantum framework for the system. Solutions for the wave function of the system are found on both the commutative and NC scenarios. It is shown that, on the commutative version, the wave function has a purely oscillatory behavior in the interior of the shell. In the NC setting, it is shown that the wave function vanishes at the singularity, as well as, at the event horizon of the black hole.

  19. Laser Heating of the Core-Shell Nanowires

    Science.gov (United States)

    Astefanoaei, Iordana; Dumitru, Ioan; Stancu, Alexandru

    2016-12-01

    The induced thermal stress in a heating process is an important parameter to be known and controlled in the magnetization process of core-shell nanowires. This paper analyses the stress produced by a laser heating source placed at one end of a core-shell type structure. The thermal field was computed with the non-Fourier heat transport equation using a finite element method (FEM) implemented in Comsol Multiphysics. The internal stresses are essentially due to thermal gradients and different expansion characteristics of core and shell materials. The stress values were computed using the thermo elastic formalism and are depending on the laser beam parameters (spot size, power etc.) and system characteristics (dimensions, thermal characteristics). Stresses in the GPa range were estimated and consequently we find that the magnetic state of the system can be influenced significantly. A shell material as the glass which is a good thermal insulator induces in the magnetic core, the smaller stresses and consequently the smaller magnetoelastic energy. These results lead to a better understanding of the switching process in the magnetic materials.

  20. Synthesis of triangular Au core-Ag shell nanoparticles

    International Nuclear Information System (INIS)

    Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali

    2007-01-01

    In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules

  1. Spectrophotometry of the shell around AG Carinae

    Science.gov (United States)

    Mitra, P. Mila; Dufour, Reginald J.

    1990-01-01

    Spatially-resolved long-slit spectrophotometry are presented for two regions of the shell nebula around the P-Cygni variable star AG Carinae. The spectra cover the 3700-6800 A wavelength range. Emission-line diagnostics are used to derive extinction, electron temperatures, and densities for various positions in the nebula. The chemical abundances and ionization structure are calculated and compared with other types of planetary nebulae and shells around other luminous stars. It is found that the N/O and N/S ratios of Ag Car are high compared to solar neighborhood ISM values. The O/H depletion found for the AG Car shell approaches that found in the condensations of the Eta Car system.

  2. Performance requirements for the single-shell tank

    International Nuclear Information System (INIS)

    GRENARD, C.E.

    1999-01-01

    This document provides performance requirements for the waste storage and waste feed delivery functions of the Single-Shell Tank (SST) System. The requirements presented here in will be used as a basis for evaluating the ability of the system to complete the single-shell tank waste feed delivery mission. They will also be used to select the technology or technologies for retrieving waste from the tanks selected for the single-shell tank waste feed delivery mission, assumed to be 241-C-102 and 241-C-104. This revision of the Performance Requirements for the SST is based on the findings of the SST Functional Analysis, and are reflected in the current System Specification for the SST System

  3. Fabrication of Magnetite/Silica/Titania Core-Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Suh Cem Pang

    2012-01-01

    Full Text Available Fe3O4/SiO2/TiO2 core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4 nanoparticles were being encapsulated within discrete silica nanospheres, and a layer of TiO2 shell was then coated directly onto each silica nanosphere. As-synthesized Fe3O4/SiO2/TiO2 core-shell nanoparticles showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of methylene blue under UV light irradiation.

  4. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results......, there are almost no studies experimentally testing their dynamic properties. To investigate the functional morphology of the bivalve shell, we employed a synthetic methodology and built an experimental setup to simulate the burrowing process. Using an evolutionary algorithm and a printer that prints three...

  5. Nitride stabilized core/shell nanoparticles

    Science.gov (United States)

    Kuttiyiel, Kurian Abraham; Sasaki, Kotaro; Adzic, Radoslav R.

    2018-01-30

    Nitride stabilized metal nanoparticles and methods for their manufacture are disclosed. In one embodiment the metal nanoparticles have a continuous and nonporous noble metal shell with a nitride-stabilized non-noble metal core. The nitride-stabilized core provides a stabilizing effect under high oxidizing conditions suppressing the noble metal dissolution during potential cycling. The nitride stabilized nanoparticles may be fabricated by a process in which a core is coated with a shell layer that encapsulates the entire core. Introduction of nitrogen into the core by annealing produces metal nitride(s) that are less susceptible to dissolution during potential cycling under high oxidizing conditions.

  6. Potential of using coconut shell particle fillers in eco-composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Sarki, J., E-mail: sarksj@yahoo.com [Department of Fire and Safety, Kaduna International Airport, Kaduna-State (Nigeria); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Samaru, Zaria (Nigeria); Hassan, S.B., E-mail: hassbolaji@yahoo.com [Department of Fire and Safety, Kaduna International Airport, Kaduna-State (Nigeria); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Samaru, Zaria (Nigeria); Aigbodion, V.S., E-mail: aigbodionv@yahoo.com [Department of Fire and Safety, Kaduna International Airport, Kaduna-State (Nigeria); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Samaru, Zaria (Nigeria); Oghenevweta, J.E. [Department of Fire and Safety, Kaduna International Airport, Kaduna-State (Nigeria); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Samaru, Zaria (Nigeria)

    2011-02-03

    Research highlights: > The production and characterization of the composites has been done. - Abstract: Morphology and mechanical properties of coconut shell particles reinforced epoxy composites were evaluated to assess the possibility of using it as a new material in engineering applications. Coconut shell filled composites were prepared from epoxy polymer matrix containing up to 30 wt% coconut shell fillers. The effects of coconut shell particle content on the mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) of the composite surfaces indicates that there are fairly good interfacial interaction between coconut shell particles and epoxy matrix. It was shown that the value of tensile modulus and tensile strength values increases with the increase of coconut shell particles content, while the impact strength slightly decreased, compared to pure epoxy resin. This work has shown that coconut shell particles can be used to improve properties of epoxy polymer composite to be used in eco-buildings.

  7. Potential of using coconut shell particle fillers in eco-composite materials

    International Nuclear Information System (INIS)

    Sarki, J.; Hassan, S.B.; Aigbodion, V.S.; Oghenevweta, J.E.

    2011-01-01

    Research highlights: → The production and characterization of the composites has been done. - Abstract: Morphology and mechanical properties of coconut shell particles reinforced epoxy composites were evaluated to assess the possibility of using it as a new material in engineering applications. Coconut shell filled composites were prepared from epoxy polymer matrix containing up to 30 wt% coconut shell fillers. The effects of coconut shell particle content on the mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) of the composite surfaces indicates that there are fairly good interfacial interaction between coconut shell particles and epoxy matrix. It was shown that the value of tensile modulus and tensile strength values increases with the increase of coconut shell particles content, while the impact strength slightly decreased, compared to pure epoxy resin. This work has shown that coconut shell particles can be used to improve properties of epoxy polymer composite to be used in eco-buildings.

  8. Studies on II-VI and III-V semiconductor nanostructures. Introduction of the core/shell/shell structure and development of CdSe nanocrystals in an automatized procedure; Untersuchungen an II-VI und III-V Halbleiternanostrukturen. Einfuehrung der Core/shell/shell-Struktur und Darstellung von CdSe-Nanokristallen in einem automatisierten Verfahren

    Energy Technology Data Exchange (ETDEWEB)

    Mekis, I.

    2005-11-15

    The work in this dissertation is focused on the development and characterization of fluorescent II-VI and III-V-Nanomaterials. Highly luminescent and photostable Nanocrystals with narrow size distributions were prepared. It was shown that nearly monodisperse CdSe-Nanocrystals could be prepared from Cd(Ac){sub 2} and TOPSe in a mixture of TOPO/TOP/HDA/TDPA. Nearly monodisperse CdSe/CdS-Core/shell-Nanocrystals have been prepared in a one-pot-synthesis by injection of H{sub 2}S-Gas into a freshly prepared crude solution of CdSe. The passivation of the CdSe-core with an inorganic shell of CdS resulted in the drastic improvement of the photoluminescence-efficiency of the colloidal solution. Reproducible room-temperature quantum yields reached up to a value of 85%. Photostability investigations have proved the enhanced stability of CdSe/CdS-Nanocrystals compared to CdSe-Nanocrystals under illumination with UV-Light. A novel type of luminescent semiconductor nanocrystal structure has been developed, consisting of a CdSe core and two anorganic shells. Highly fluorescent and nearly monodisperse CdSe/CdS/ZnS- and CdSe/ZnSe/ZnS-Core/shell/shell-nanocrystals have been prepared via organometallic- and acetate-precursors. The Core/she ll/shell particles reached reproducible room-temperature quantum yields up to 85%. Photostability investigations among CdSe-core, CdSe/CdS-Core/shell- and CdSe/CdS/ZnS- Core/shell/-shell-nanocrystals under illumination with UV-light have proved the highest photostability of the Core/shell/shell-particles. The photostabilities of CdSe/ZnSe/ZnS-and CdSe/ZnS-nanocrystals were compared under illumination with intense laser-beam in air. Another part of this work focused on the development of an automated synthesis procedure of CdSe-nanocrystals by constructing and implementing a flow-reactor system. The size and structure of prepared nanocrystals depended considerably on the Cd:Se-precursorratio and the flow-rate. The preparation of CdSe using Cd(Ac)2

  9. Proton induced X-ray emission analysis of aberrant cowrie shells

    International Nuclear Information System (INIS)

    Luta, A.M.; Kravchenko, I.I.; Dunnam, F.E.; Van Rinsvelt, H.A.; Meyer, C.P.

    2004-01-01

    It is hypothesized that the irregular growth and coloring of aberrant rostrate and melanistic cowrie shells are the result of intensification of the melanain biochemical pathway caused by an overabundance of spin-stabilizing heavy metals. PIXE measurements have shown no pattern in elemental composition to stand out as a distinct difference between the normal and aberrant shells. Therefore, no evidence was found in the shell to corroborate the role of heavy metals in causing these teratologies. The absence of heavy element abundance in rostrate and melanistic shells does not exclude the possible role that these elements play within the soft tissue, as these metals may be too large to pass through membrane channels into the extracellular space where shell deposition occurs

  10. Creep deformations of shells of revolution under asymmetrical loading

    International Nuclear Information System (INIS)

    Takezono, S.

    1975-01-01

    The numerical analysis of creep deformations of shells of revolution under unsymmetrical loads is described with application to a cylindrical shell. The analytical formulation of the creep of axisymmetric undergoing unsymmetrical deformations is developed for two hardening laws: the time hardening law and the strain hardening law. The method is based on the creep power law, and on the assumption of plane stress condition and the Euler-Bernoulli hypothesis used in the ordinary thin shell theory. The basic differential equations derived for incremental values with respect to time are numerically solved by a finite difference method and the solutions at any time are obtained by integration of the incremental values. In conclusion the computer programs are developed which can be used to predict the creep deformations of arbitrary axisymmetrical shells. As a numerical example the creep deformation of cylindrical shell of importance in practical use is treated, and the variations of displacements and internal forces with the lapse of time are discussed

  11. Pion-nucleon vertex function with an off-shell nucleon

    International Nuclear Information System (INIS)

    Nutt, W.T.; Shakin, C.M.

    1977-01-01

    A model calculation for the π-N vertex function is presented in the case in which there is a single off-mass-shell nucleon and a (nearly) on-mass-shell pion. Very strong effects due to the P 11 resonance at 1470 MeV are found. A simple parametrization of the vertex function is prvided in the case that at least one nucleon is on its mass shell. (Auth.)

  12. Exploring the potential of climate adaptive building shells

    NARCIS (Netherlands)

    Loonen, R.C.G.M.; Trcka, M.; Hensen, J.L.M.

    2011-01-01

    Building shells with adaptive, rather than static properties, intuitively offer opportunities for both energy savings and comfort enhancements. Progress in this field is characterized by fragmented developments, and the most effective type of climate adaptive building shell (CABS) behaviour is still

  13. Determination of K shell absorption jump factors and jump ratios of 3d transition metals by measuring K shell fluorescence parameters

    International Nuclear Information System (INIS)

    Kaçal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

    2015-01-01

    Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature. - Highlights: • This work regard the K shell absorption jump ratios and jump factors of Ti, Cr, Fe, Co, Ni and Cu. • This paper presents the first measurement of these parameters using the experimental K shell fluorescence parameters. • A good agreement was found between experimental and theoretical values. • The EDXRF technique was suitable, precise and reliable for the measurement of these atomic parameters

  14. Fabrication of Ni@Ti core-shell nanoparticles by modified gas aggregation source

    Science.gov (United States)

    Hanuš, J.; Vaidulych, M.; Kylián, O.; Choukourov, A.; Kousal, J.; Khalakhan, I.; Cieslar, M.; Solař, P.; Biederman, H.

    2017-11-01

    Ni@Ti core-shell nanoparticles were prepared by a vacuum based method using the gas aggregation source (GAS) of nanoparticles. Ni nanoparticles fabricated in the GAS were afterwards coated by a Ti shell. The Ti shell was deposited by means of magnetron sputtering. The Ni nanoparticles were decelerated in the vicinity of the magnetron to the Ar drift velocity in the second deposition chamber. X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy analysis of the nanoparticles showed the core-shell structure. It was shown that the thickness of the shell can be easily tuned by the process parameters with a maximum achieved thickness of the Ti shell ~2.5 nm. The core-shell structure was confirmed by the STEM analysis of the particles.

  15. Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell

    Directory of Open Access Journals (Sweden)

    Nam-Hee Park

    2015-07-01

    Full Text Available To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface.

  16. Shell effects in the superasymmetric fission

    CERN Document Server

    Mirea, M

    2002-01-01

    A new formalism based on the Landau-Zener promotion mechanism intends to explain the fine structure of alpha and cluster decay. The analysis of this phenomenon is accomplished by following the modality in which the shells are reorganized during the decay process beginning with the initial ground state of the parent towards the final configuration of two separated nuclei. A realistic level scheme is obtained in the framework of the superasymmetric two-center shell model. (author)

  17. Synthesis of low density foam shells for inertial confinement fusion experiments

    International Nuclear Information System (INIS)

    Lattaud, Cecile

    2011-01-01

    This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60 C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between the internal water phase and the organic phase increases, the TMPTMA shells non-concentricity improves. A density gap of 0.078 g.cm -3 at 60 C, leads to an average non-concentricity of 2.4% with a yield of shells of 58%. It was also shown that the synthesis process can be considered as reproducible. While using the same internal water phase, equivalent non-concentricity results are obtained using either a straight tube, a tube with areas of constriction or a short wound tube. The time required to fix the shell's shape is at least 20 minutes with thermal polymerization. So, it seems that the time spent by the shells inside the rotating flask allows the centering of the internal water phase inside the organic phase, whatever the circulation process used. In order to get higher polymerization rates and to avoid destabilization phenomena, we then focused our study on photo polymerization. When the synthesis is performed using a UV lamp with an efficient light intensity, the shells have a slightly higher thickness than the shells synthesized by thermal polymerization. Moreover, a really higher yield, around 80%, is achieved with UV polymerization. However, the average non-concentricity of the shells synthesized lays around 20%, which is really high compared to the 2.4% average

  18. Meta-shell Approach for Constructing Lightweight and High Resolution X-Ray Optics

    Science.gov (United States)

    McClelland, Ryan S.

    2016-01-01

    Lightweight and high resolution optics are needed for future space-based x-ray telescopes to achieve advances in high-energy astrophysics. Past missions such as Chandra and XMM-Newton have achieved excellent angular resolution using a full shell mirror approach. Other missions such as Suzaku and NuSTAR have achieved lightweight mirrors using a segmented approach. This paper describes a new approach, called meta-shells, which combines the fabrication advantages of segmented optics with the alignment advantages of full shell optics. Meta-shells are built by layering overlapping mirror segments onto a central structural shell. The resulting optic has the stiffness and rotational symmetry of a full shell, but with an order of magnitude greater collecting area. Several meta-shells so constructed can be integrated into a large x-ray mirror assembly by proven methods used for Chandra and XMM-Newton. The mirror segments are mounted to the meta-shell using a novel four point semi-kinematic mount. The four point mount deterministically locates the segment in its most performance sensitive degrees of freedom. Extensive analysis has been performed to demonstrate the feasibility of the four point mount and meta-shell approach. A mathematical model of a meta-shell constructed with mirror segments bonded at four points and subject to launch loads has been developed to determine the optimal design parameters, namely bond size, mirror segment span, and number of layers per meta-shell. The parameters of an example 1.3 m diameter mirror assembly are given including the predicted effective area. To verify the mathematical model and support opto-mechanical analysis, a detailed finite element model of a meta-shell was created. Finite element analysis predicts low gravity distortion and low thermal distortion. Recent results are discussed including Structural Thermal Optical Performance (STOP) analysis as well as vibration and shock testing of prototype meta-shells.

  19. Host susceptibility hypothesis for shell disease in American lobsters.

    Science.gov (United States)

    Tlusty, Michael F; Smolowitz, Roxanna M; Halvorson, Harlyn O; DeVito, Simone E

    2007-12-01

    Epizootic shell disease (ESD) in American lobsters Homarus americanus is the bacterial degradation of the carapace resulting in extensive irregular, deep erosions. The disease is having a major impact on the health and mortality of some American lobster populations, and its effects are being transferred to the economics of the fishery. While the onset and progression of ESD in American lobsters is undoubtedly multifactorial, there is little understanding of the direct causality of this disease. The host susceptibility hypothesis developed here states that although numerous environmental and pathological factors may vary around a lobster, it is eventually the lobster's internal state that is permissive to or shields it from the final onset of the diseased state. To support the host susceptibility hypothesis, we conceptualized a model of shell disease onset and severity to allow further research on shell disease to progress from a structured model. The model states that shell disease onset will occur when the net cuticle degradation (bacterial degradation, decrease of host immune response to bacteria, natural wear, and resorption) is greater than the net deposition (growth, maintenance, and inflammatory response) of the shell. Furthermore, lesion severity depends on the extent to which cuticle degradation exceeds deposition. This model is consistent with natural observations of shell disease in American lobster.

  20. Core@shell Nanoparticles: Greener Synthesis Using Natural Plant Products

    Directory of Open Access Journals (Sweden)

    Mehrdad Khatami

    2018-03-01

    Full Text Available Among an array of hybrid nanoparticles, core-shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the center, while the other material/materials that were located around the central core develops a shell. Core-shell nanostructures are useful entities with high thermal and chemical stability, lower toxicity, greater solubility, and higher permeability to specific target cells. Plant or natural products-mediated synthesis of nanostructures refers to the use of plants or its extracts for the synthesis of nanostructures, an emerging field of sustainable nanotechnology. Various physiochemical and greener methods have been advanced for the synthesis of nanostructures, in contrast to conventional approaches that require the use of synthetic compounds for the assembly of nanostructures. Although several biological resources have been exploited for the synthesis of core-shell nanoparticles, but plant-based materials appear to be the ideal candidates for large-scale green synthesis of core-shell nanoparticles. This review summarizes the known strategies for the greener production of core-shell nanoparticles using plants extract or their derivatives and highlights their salient attributes, such as low costs, the lack of dependence on the use of any toxic materials, and the environmental friendliness for the sustainable assembly of stabile nanostructures.