Behavioral Immunity Suppresses an Epizootic in Caribbean Spiny Lobsters.

Science.gov (United States)

Butler, Mark J; Behringer, Donald C; Dolan, Thomas W; Moss, Jessica; Shields, Jeffrey D

2015-01-01

Sociality has evolved in a wide range of animal taxa but infectious diseases spread rapidly in populations of aggregated individuals, potentially negating the advantages of their social interactions. To disengage from the coevolutionary struggle with pathogens, some hosts have evolved various forms of "behavioral immunity"; yet, the effectiveness of such behaviors in controlling epizootics in the wild is untested. Here we show how one form of behavioral immunity (i.e., the aversion of diseased conspecifics) practiced by Caribbean spiny lobsters (Panulirus argus) when subject to the socially transmitted PaV1 virus, appears to have prevented an epizootic over a large seascape. We capitalized on a "natural experiment" in which a die-off of sponges in the Florida Keys (USA) resulted in a loss of shelters for juvenile lobsters over a ~2500km2 region. Lobsters were thus concentrated in the few remaining shelters, presumably increasing their exposure to the contagious virus. Despite this spatial reorganization of the population, viral prevalence in lobsters remained unchanged after the sponge die-off and for years thereafter. A field experiment in which we introduced either a healthy or PaV1-infected lobster into lobster aggregations in natural dens confirmed that spiny lobsters practice behavioral immunity. Healthy lobsters vacated dens occupied by PaV1-infected lobsters despite the scarcity of alternative shelters and the higher risk of predation they faced when searching for a new den. Simulations from a spatially-explicit, individual-based model confirmed our empirical results, demonstrating the efficacy of behavioral immunity in preventing epizootics in this system.

Behavioral Immunity Suppresses an Epizootic in Caribbean Spiny Lobsters.

Directory of Open Access Journals (Sweden)

Mark J Butler

Full Text Available Sociality has evolved in a wide range of animal taxa but infectious diseases spread rapidly in populations of aggregated individuals, potentially negating the advantages of their social interactions. To disengage from the coevolutionary struggle with pathogens, some hosts have evolved various forms of "behavioral immunity"; yet, the effectiveness of such behaviors in controlling epizootics in the wild is untested. Here we show how one form of behavioral immunity (i.e., the aversion of diseased conspecifics practiced by Caribbean spiny lobsters (Panulirus argus when subject to the socially transmitted PaV1 virus, appears to have prevented an epizootic over a large seascape. We capitalized on a "natural experiment" in which a die-off of sponges in the Florida Keys (USA resulted in a loss of shelters for juvenile lobsters over a ~2500km2 region. Lobsters were thus concentrated in the few remaining shelters, presumably increasing their exposure to the contagious virus. Despite this spatial reorganization of the population, viral prevalence in lobsters remained unchanged after the sponge die-off and for years thereafter. A field experiment in which we introduced either a healthy or PaV1-infected lobster into lobster aggregations in natural dens confirmed that spiny lobsters practice behavioral immunity. Healthy lobsters vacated dens occupied by PaV1-infected lobsters despite the scarcity of alternative shelters and the higher risk of predation they faced when searching for a new den. Simulations from a spatially-explicit, individual-based model confirmed our empirical results, demonstrating the efficacy of behavioral immunity in preventing epizootics in this system.

Epizootic ulcerative syndrome: Exotic fish disease threatens Africa’s aquatic ecosystems

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Karl D.A. Huchzermeyer

2012-09-01

Full Text Available In late 2006 an unusual ulcerative condition in wild fish was reported for the first time in Africa from the Chobe and upper Zambezi Rivers in Botswana and Namibia. Concern increased with subsistence fishermen reporting large numbers of ulcerated fish in their catches. In April 2007 the condition was confirmed as an outbreak of epizootic ulcerative syndrome (EUS. The causative agent, Aphanomyces invadans, is a pathogenic water mould of fish that shows little host specificity. Ulcers follow infection of tissues by oomycete zoospores, resulting in a granulomatous inflammation associated with invading oomycete hyphae. Granulomatous tracts surrounding oomycete hyphae within the necrotic tissues characterise the diagnostic histological picture. The upper Zambezi floodplain at the confluence with the Chobe River spans the four countries of Botswana, Namibia, Zambia and Zimbabwe, making disease control a challenge. The floodplain ecosystem supports a high fish diversity of around 80 species, and is an important breeding and nursery ground. The annual cycle of flooding brings about changes in water quality that are thought to favour the infectivity of A. invadans, with diseased fish appearing soon after the plains become flooded. Since 2006 the disease has spread rapidly upstream along the upper Zambezi and its tributaries. By 2010 the disease was reported from the Okavango Delta in Botswana and in 2011 from the Western Cape Province of South Africa. EUS has the potential to disrupt floodplain ecosystems elsewhere in Africa where high fish diversity forms the basis of subsistence fisheries and local economies, and is a direct threat to freshwater fish culture.

Genetic diversity and phylogenetic analysis of the attachment glycoprotein of phocine distemper viruses of the 2002 and 1988 epizootics

DEFF Research Database (Denmark)

Nielsen, L; Arctander, P; Jensen, T H

2009-01-01

To investigate the possible origin and spread of the dramatic re-emergent 2002 distemper epizootic observed among seals in Danish Waters, we have sequenced wild-type genes of the attachment (H) glycoproteins of viruses from both the 2002 and 1988 epizootics. Phylogenetic analysis of the H genes...... of phocine distemper virus (PDV) together with other morbilliviruses, suggests that the re-emergent 2002 PDV is more closely related to a putative recent ancestral PDV than the 1988 PDV isolates. Moreover, upsurges of distemper disease in land-living carnivores linked in time and locality to the 2002 seal...... epizootic in Danish Waters was investigated and determined to be caused by canine distemper virus, the closest relative of PDV, revealing no direct epidemiological link to the seal epizootics. (C) 2009 Elsevier B.V. All rights reserved....

Vector competence of Culicoides sonorensis (Diptera: Ceratopogonidae to epizootic hemorrhagic disease virus serotype 7

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Ruder Mark G

2012-10-01

Full Text Available Abstract Background Culicoides sonorensis (Diptera: Ceratopogonidae is a vector of epizootic hemorrhagic disease virus (EHDV serotypes 1 and 2 in North America, where these viruses are well-known pathogens of white-tailed deer (WTD and other wild ruminants. Although historically rare, reports of clinical EHDV infection in cattle have increased in some parts of the world over the past decade. In 2006, an EHDV-7 epizootic in cattle resulted in economic loss for the Israeli dairy industry. White-tailed deer are susceptible to EHDV-7 infection and disease; however, this serotype is exotic to the US and the susceptibility of C. sonorensis to this cattle-virulent EHDV is not known. The objective of the study was to determine if C. sonorensis is susceptible to EHDV-7 infection and is a competent vector. Methods To evaluate the susceptibility of C. sonorensis, midges were fed on EHDV-7 infected WTD, held at 22 ± 1°C, and processed individually for virus isolation and titration on 4–16 days post feeding (dpf. Midges with a virus titer of ≥102.7 median tissue culture infective doses (TCID50/midge were considered potentially competent. To determine if infected C. sonorensis were capable of transmitting EHDV-7 to a host, a susceptible WTD was then fed on by a group of 14–16 dpf midges. Results From 4–16 dpf, 45% (156/350 of midges that fed on WTD with high titer viremia (>107 TCID50/ml were virus isolation-positive, and starting from 10–16 dpf, 32% (35/109 of these virus isolation-positive midges were potentially competent (≥102.7 TCID50/midge. Midges that fed on infected deer transmitted the virus to a susceptible WTD at 14–16 dpf. The WTD developed viremia and severe clinical disease. Conclusion This study demonstrates that C. sonorensis is susceptible to EHDV-7 infection and can transmit the virus to susceptible WTD, thus, C. sonorensis should be considered a potential vector of EHDV-7. Together with previous work, this study demonstrates

Vector competence of Culicoides sonorensis (Diptera: Ceratopogonidae) to epizootic hemorrhagic disease virus serotype 7.

Science.gov (United States)

Ruder, Mark G; Howerth, Elizabeth W; Stallknecht, David E; Allison, Andrew B; Carter, Deborah L; Drolet, Barbara S; Klement, Eyal; Mead, Daniel G

2012-10-17

Culicoides sonorensis (Diptera: Ceratopogonidae) is a vector of epizootic hemorrhagic disease virus (EHDV) serotypes 1 and 2 in North America, where these viruses are well-known pathogens of white-tailed deer (WTD) and other wild ruminants. Although historically rare, reports of clinical EHDV infection in cattle have increased in some parts of the world over the past decade. In 2006, an EHDV-7 epizootic in cattle resulted in economic loss for the Israeli dairy industry. White-tailed deer are susceptible to EHDV-7 infection and disease; however, this serotype is exotic to the US and the susceptibility of C. sonorensis to this cattle-virulent EHDV is not known. The objective of the study was to determine if C. sonorensis is susceptible to EHDV-7 infection and is a competent vector. To evaluate the susceptibility of C. sonorensis, midges were fed on EHDV-7 infected WTD, held at 22 ± 1°C, and processed individually for virus isolation and titration on 4-16 days post feeding (dpf). Midges with a virus titer of ≥ 10(2.7) median tissue culture infective doses (TCID(50))/midge were considered potentially competent. To determine if infected C. sonorensis were capable of transmitting EHDV-7 to a host, a susceptible WTD was then fed on by a group of 14-16 dpf midges. From 4-16 dpf, 45% (156/350) of midges that fed on WTD with high titer viremia (>10(7) TCID(50)/ml) were virus isolation-positive, and starting from 10-16 dpf, 32% (35/109) of these virus isolation-positive midges were potentially competent (≥ 10(2.7) TCID(50)/midge). Midges that fed on infected deer transmitted the virus to a susceptible WTD at 14-16 dpf. The WTD developed viremia and severe clinical disease. This study demonstrates that C. sonorensis is susceptible to EHDV-7 infection and can transmit the virus to susceptible WTD, thus, C. sonorensis should be considered a potential vector of EHDV-7. Together with previous work, this study demonstrates that North America has a susceptible ruminant and

Causes of pneumonia epizootics among bighorn sheep, Western United States, 2008-2010.

Science.gov (United States)

Besser, Thomas E; Highland, Margaret A; Baker, Katherine; Cassirer, E Frances; Anderson, Neil J; Ramsey, Jennifer M; Mansfield, Kristin; Bruning, Darren L; Wolff, Peregrine; Smith, Joshua B; Jenks, Jonathan A

2012-03-01

Epizootic pneumonia of bighorn sheep is a devastating disease of uncertain etiology. To help clarify the etiology, we used culture and culture-independent methods to compare the prevalence of the bacterial respiratory pathogens Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida, and Mycoplasma ovipneumoniae in lung tissue from 44 bighorn sheep from herds affected by 8 outbreaks in the western United States. M. ovipneumoniae, the only agent detected at significantly higher prevalence in animals from outbreaks (95%) than in animals from unaffected healthy populations (0%), was the most consistently detected agent and the only agent that exhibited single strain types within each outbreak. The other respiratory pathogens were frequently but inconsistently detected, as were several obligate anaerobic bacterial species, all of which might represent secondary or opportunistic infections that could contribute to disease severity. These data provide evidence that M. ovipneumoniae plays a primary role in the etiology of epizootic pneumonia of bighorn sheep.

Emergence of epizootic ulcerative syndrome in native fish of the Murray-Darling River System, Australia: hosts, distribution and possible vectors.

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Craig A Boys

Full Text Available Epizootic ulcerative syndrome (EUS is a fish disease of international significance and reportable to the Office International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua, Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled from the Murray-Darling River System (MDRS between Bourke and Brewarrina, New South Wales Australia. Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor. Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS, supporting previous accounts of resistance against the disease by this species. The lack of previous clinical evidence, the large number of new hosts (n = 3, the geographic extent (200 km of this epizootic, the severity of ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans. The epizootic and associated environmental factors are documented and discussed within the context of possible vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and biosecurity are made.

Causes of Pneumonia Epizootics among Bighorn Sheep, Western United States, 2008–2010

Science.gov (United States)

Highland, Margaret A.; Baker, Katherine; Cassirer, E. Frances; Anderson, Neil J.; Ramsey, Jennifer M.; Mansfield, Kristin; Bruning, Darren L.; Wolff, Peregrine; Smith, Joshua B.; Jenks, Jonathan A.

2012-01-01

Epizootic pneumonia of bighorn sheep is a devastating disease of uncertain etiology. To help clarify the etiology, we used culture and culture-independent methods to compare the prevalence of the bacterial respiratory pathogens Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida, and Mycoplasma ovipneumoniae in lung tissue from 44 bighorn sheep from herds affected by 8 outbreaks in the western United States. M. ovipneumoniae, the only agent detected at significantly higher prevalence in animals from outbreaks (95%) than in animals from unaffected healthy populations (0%), was the most consistently detected agent and the only agent that exhibited single strain types within each outbreak. The other respiratory pathogens were frequently but inconsistently detected, as were several obligate anaerobic bacterial species, all of which might represent secondary or opportunistic infections that could contribute to disease severity. These data provide evidence that M. ovipneumoniae plays a primary role in the etiology of epizootic pneumonia of bighorn sheep. PMID:22377321

Epizootic of ovine congenital malformations associated with Schmallenberg virus infection

NARCIS (Netherlands)

Brom, van der R.; Luttikholt, S.J.; Lievaart-Peterson, K.; Peperkamp, N.H.M.T.; Mars, M.H.; Poel, van der W.H.M.; Vellema, P.

2012-01-01

Epizootic outbreaks of congenital malformations in sheep are rare and have, to the best of our knowledge, never been reported before in Europe. This paper describes relevant preliminary findings from the first epizootic outbreak of ovine congenital malformations in the Netherlands. Between 25

Novel serotype of bluetongue virus in South America and first report of epizootic haemorrhagic disease virus in Ecuador.

Science.gov (United States)

Verdezoto, J; Breard, E; Viarouge, C; Quenault, H; Lucas, P; Sailleau, C; Zientara, S; Augot, D; Zapata, S

2018-02-01

Bluetongue virus (BTV) and Epizootic haemorrhagic disease virus (EHDV) are closely related Orbiviruses that affect domestic and wild ruminants. In Ecuador previous serological studies reported the presence of BTV; however, no data are available about the presence of EHDV. In this study, 295 cattle without symptoms of infection were sampled from two farms located in Andean and Amazonian regions and from a slaughterhouse in the coastal region. ELISA analyses showed high prevalence of BTV (98.9%) and EHDV (81.3%) antibodies, and RT-qPCRs revealed the presence of EHDV (24.1%) and BTV (10.2%) genomes in cattle blood samples. Viral isolation allowed to identify EHDV serotype 1 (EHDV1) and BTV serotypes 9 (BTV9), 13 and 18. These findings suggest that BTV and EHDV are enzootic diseases in Ecuador. © 2017 Blackwell Verlag GmbH.

[The epizootic characteristics of tularemia in the Crimea].

Science.gov (United States)

Alekseev, A F; Chirniĭ, V I; Bogatyreva, L M; Tovpinets, N N; Evstaf'ev, I L; Markeshin, S Ia; Kovin, V V; Evstratov, Iu V; Zakharova, T F; Galushko, V I

1996-01-01

Cases of tularemia were registered in the Crimea both before and after planned immunization. In 1981-1993 in 4.000 localities 35,100 mammals, 27,400 ectoparasites, 8,800 feces left by birds of prey and foxes and 900 environmental specimens were studied. 137 Francisella tularensis strains were isolated. Field mapping of the spread of F.tularensis and places of habitation of small mammals was carried out. The active polyhostal natural focus of tularemia was found to exist on the Kerch Peninsula, less affected by anthropogenic factors, where tularemia morbidity among humans, and tularemia epizootic coincided with the maximum rises in the number of myomorphs. The core of the focus constituted 2.4% of its area and were characterized by the stable complex of Ixodes ticks and the preservation of F. tularensis in the environment. In other regions of the flat part of the Crimea with considerable anthropogenic transformations of the landscape rises in tularemia epizootics and tularemia morbidity in humans were rare. In the mountainous part of the Crimea tularemia epizootics were registered only by the detection of specific antibodies and antigens.

Review of the 2012 Epizootic Hemorrhagic Disease Outbreak in Domestic Ruminants in the United States.

Directory of Open Access Journals (Sweden)

G Stevens

Full Text Available An unusually large number of cases of Epizootic hemorrhagic disease (EHD were observed in United States cattle and white-tailed deer in the summer and fall of 2012. USDA APHIS Veterinary Services area offices were asked to report on foreign animal disease investigations and state diagnostic laboratory submissions which resulted in a diagnosis of EHD based on positive PCR results. EHD was reported in the following species: cattle (129 herds, captive white-tailed deer (65 herds, bison (8 herds, yak (6 herds, elk (1 herd, and sheep (1 flock. A majority of the cases in cattle and bison were found in Nebraska, South Dakota, and Iowa. The majority of cases in captive white-tailed deer were found in Ohio, Iowa, Michigan, and Missouri. The most common clinical sign observed in the cattle and bison herds was oral lesions. The major observation in captive white-tailed deer herds was death. Average within-herd morbidity was 7% in cattle and bison herds, and 46% in captive white-tailed deer herds. The average within-herd mortality in captive white-tailed deer herds was 42%.

A serosurvey of bluetongue and epizootic haemorrhagic disease in a convenience sample of sheep and cattle herds in Zimbabwe.

Science.gov (United States)

Gordon, Stuart J G; Bolwell, Charlotte; Rogers, Chris W; Musuka, Godfrey; Kelly, Patrick; Guthrie, Alan; Mellor, Philip S; Hamblin, Chris

2017-11-14

A convenience sample of sheep and cattle herds around the cities of Harare, Kwekwe and Bulawayo, located in the Highveld region of Zimbabwe, was used to estimate the seroprevalence and sero-incidence of bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) antibodies. A competitive enzyme-linked immunosorbent assay was used to identify serum antibodies against BTV and EHDV across three rainy seasons. The median sero-prevalence of BTV and EHDV antibodies in cattle was 62% (interquartile range [IQR]: 30-89) and 56% (IQR: 5-77), respectively. In sheep, the median sero-prevalence of BTV and EHDV was 41% (IQR: 19-63) and 0% (IQR: 0-21), respectively. Median sero-incidences of BTV and EHDV antibodies in cattle of 43% (IQR: 22-67) and 27% (IQR: 9-57) respectively were recorded. The median sero-incidence of BTV in sheep was 14% (IQR: 6-23). Based on these preliminary findings, animal health workers in Zimbabwe should continue to monitor the exposure rates of cattle and sheep to BTV and consider the possibility of strains emerging with increased pathogenicity. There are no previous published reports of antibodies against EHDV in Zimbabwe so the possibility of epizootic haemorrhagic disease existing in domestic livestock should now be considered by Zimbabwean animal health officials. Seroconversions to BTV and EHDV occurred predominantly at the end of each rainy season (March and April), which generally corresponds to high numbers of the Culicoides vectors. BTV isolations were made from three individual cows in two of the sentinel herds and all three were identified as serotype 3. This is the first time BTV serotype 3 has been recorded in Zimbabwe, although its presence in neighbouring South Africa is well documented.

Investigation of a Possible Link Between Vaccination and the 2010 Sheep Pox Epizootic in Morocco.

Science.gov (United States)

Haegeman, A; Zro, K; Sammin, D; Vandenbussche, F; Ennaji, M M; De Clercq, K

2016-12-01

Sheep pox is endemic in most parts of Northern Africa and has the potential to cause severe economic problems. Live attenuated vaccines are used in Morocco, and in many other countries, to control the disease. Sheep pox virus (SPPV) re-appeared in 2010 causing a nodular clinical form previously not observed in Morocco. The severe clinical signs observed during the course of this outbreak and initial reports citing similarity in nucleotide sequence between the Moroccan vaccine strain and field isolates warranted a more in depth analysis of this epizootic. In this study, sequence analysis showed that isolates obtained from four provinces of eastern Morocco were identical, demonstrating that a single SPPV strain was responsible for the 2010 epizootic. In addition, the genome fragments sequenced and phylogenetic analyses undertaken as part of this study showed significant differences between field isolates and the Moroccan vaccine strain. New PCR methods were developed to differentiate between wild-type isolates and vaccine strains of SPPV. Using these methods, no trace of wild-type SPPV was found in the vaccine and no evidence was found to suggest that the vaccine strain was causing clinical disease. © 2015 Blackwell Verlag GmbH.

Post-epizootic chronic dolphin morbillivirus infection in Mediterranean striped dolphins Stenella coeruleoalba.

Science.gov (United States)

Soto, Sara; Alba, Ana; Ganges, Llilianne; Vidal, Enric; Raga, Juan Antonio; Alegre, Ferrán; González, Beatriz; Medina, Pascual; Zorrilla, Irene; Martínez, Jorge; Marco, Alberto; Pérez, Mónica; Pérez, Blanca; Pérez de Vargas Mesas, Ana; Martínez Valverde, Rosa; Domingo, Mariano

2011-10-06

Dolphin morbillivirus (DMV) has caused 2 epizootics with high mortality rates on the Spanish Mediterranean coast, in 1990 and 2006-07, mainly affecting striped dolphins Stenella coeruleoalba. Following the first epizootic unusual DMV infections affecting only the central nervous system of striped dolphins were found, with histological features similar to subacute sclerosing panencephalitis and old dog encephalitis, the chronic latent localised infections caused by defective forms of measles virus and canine distemper virus, respectively. Between 2008 and 2010, monitoring by microscopic and immunohistochemical (IHC) studies of 118 striped dolphins stranded along Catalonia, the Valencia Region and Andalusia showed similar localised DMV nervous system infections in 25.0, 28.6 and 27.4% of cases, respectively, with no significant differences among regions or sex. The body length of DMV-infected dolphins was statistically greater than that of non-infected dolphins (196.5 vs. 160.5 cm; p dolphins with positive IHC-DMV had positive PCR results. All 6 cases were positive with the 78 bp RT-PCR. These findings contraindicate the use of the 429 bp RT-PCR protocol based on the P gene to detect this specific form of DMV. DMV localised nervous infection constitutes the most relevant single cause of stranding and death in Mediterranean striped dolphins in the years following a DMV epizootic, and it might even overwhelm the effects of the epizootic itself, at least in 2007.

Identification of Two Pathogenic Aeromonas Species Isolated during Production Related Epizootics from Juvenile Burbot Lota lota maculosa.

Science.gov (United States)

Terrazas, Marc M; Anderson, Cort L; Jacobs, Sarah J; Cain, Kenneth D

2018-05-25

In response to population declines of Burbot Lota lota maculosa, conservation aquaculture methods have been developed for this species. In general, Burbot are relatively resistant to many salmonid pathogens; however, cultured juvenile Burbot have experienced periodic epizootic disease outbreaks during production. A series of trials were conducted to determine the virulence of select bacteria isolated from juvenile Burbot following outbreaks that occurred in 2012 and 2013 at the University of Idaho's Aquaculture Research Institute. Initial clinical diagnostics and sampling resulted in the isolation of numerous putative bacterial pathogens. To determine which bacteria were the most likely causative agents contributing to these epizootics, juvenile Burbot were injectied intraperitoneally (IP) with select bacteria in log phase growth. Mortality associated with specific isolates was recorded, and more comprehensive challenges followed this initial screening. These challenges used side-by-side IP and immersion methods to expose Burbot to potential pathogens. The challenges resulted in significantly higher mortalities in fish following IP injection of two Aeromonas sp. isolates compared to controls (P ≤ 0.01), but no difference in mortality for immersion challenged groups was observed (P = 0.42). Results demonstrate that two isolates (Aeromonas sp.) cultured from the epizootics are virulent to Burbot. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Epizootic of ovine congenital malformations associated with Schmallenberg virus infection.

Science.gov (United States)

van den Brom, R; Luttikholt, S J M; Lievaart-Peterson, K; Peperkamp, N H M T; Mars, M H; van der Poel, W H M; Vellema, P

2012-02-01

Epizootic outbreaks of congenital malformations in sheep are rare and have, to the best of our knowledge, never been reported before in Europe. This paper describes relevant preliminary findings from the first epizootic outbreak of ovine congenital malformations in the Netherlands. Between 25 November and 20 December 2011, congenital malformations in newborn lambs on sheep farms throughout the country were reported to the Animal Health Service in Deventer. Subsequently, small ruminant veterinary specialists visited these farms and collected relevant information from farmers by means of questionnaires. The deformities varied from mild to severe, and ewes were reported to have given birth to both normal and deformed lambs; both male and female lambs were affected. Most of the affected lambs were delivered at term. Besides malformed and normal lambs, dummy lambs, unable to suckle, were born also on these farms. None of the ewes had shown clinical signs during gestation or at parturition. Dystocia was common, because of the lambs' deformities. Lambs were submitted for post-mortem examination, and samples of brain tissue were collected for virus detection. The main macroscopic findings included arthrogryposis, torticollis, scoliosis and kyphosis, brachygnathia inferior, and mild-to-marked hypoplasia of the cerebrum, cerebellum and spinal cord. Preliminary data from the first ten affected farms suggest that nutritional deficiencies, intoxication, and genetic factors are not likely to have caused the malformations. Preliminary diagnostic analyses of precolostral serum samples excluded border disease virus, bovine viral diarrhoea virus, and bluetongue virus. In December 2011, samples of brain tissue from 54 lambs were sent to the Central Veterinary Institute of Wageningen University Research, Lelystad. Real-time PCR detected the presence of a virus, provisionally named the Schmallenberg virus, in brain tissue from 22 of the 54 lambs, which originated from seven of eight

The impact of the territory contamination on the epizootic process of cattle infection

International Nuclear Information System (INIS)

Rusinovich, A.A.

2001-01-01

The article deals with specifying the influence of natural, geographic and ecological conditions on the epizootic process of cattle infection. The tests were conducted in northern districts with no territorial contamination and in the two contaminated southern farms in Vetka and Narovlya districts, having 15-40 curie/sq.km. The results on the intensity of cattle infections, clinic-morphological and immunological properties of the infection proved that the epizootic process of cattle infection in Chernobyl affected areas differ from clean districts. Last years the veterinary science and practice pay significant attention to studying of ecological factors influence on the development of infectious and noncontagious pathology at animals. For Belarus studying features and laws of development and cattle infection display under the consequences of Chernobyl atomic power station disaster is actual. The stimulating affection of radioactive radiation on hemablastosis development at animals and people is known. As a consequence of Chernobyl disaster, 2/3 of radionuclides emissions were scattered on the territory of Belarus. At the same time, according to the available data, in post Chernobyl period on contaminated territories people diseases have considerably increased, especially children and liquidators, including oncological diseases. For the definition of natural-geographical zones and ecological conditions influence 5 collective farms in northern areas without contamination and one collective farm in the south of republic with contamination were picked up. Originally researches on the definition of correlation factor between intensity of cows infecting by leukemia virus in clean and contaminated areas with approximately equal initial epizootic situation of the infection both in spontaneous conditions, and at realization anti leukemia actions. By the analysis of epizootic data it is established, that the rates of this parameter reduction are caused by work on leukemia

The effect of temperature on the in vitro transcriptase reaction of bluetongue virus, epizootic haemorrhagic disease virus and African horsesickness virus

International Nuclear Information System (INIS)

Van Dijk, A.A.; Huismans, H.

1982-01-01

Virions of bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV) and African horsesickness virus (AHSV) can be converted to core particles by treatment with chymotrypsin and magnesium. The conversion is characterized by the removal of the 2 outer capsid polypeptides of the virion. The loss of these 2 proteins results in an increase in density from 1,36 g/ml to 1,40 g/ml on CsCl gradients. The BTV, EHDV and AHSV core particles have an associated double-stranded RNA dependent RNA transcriptase that appears to transcribe mRNA optimally at 28 degrees Celsius. It was found, at least in the case of BTV, that this low temperature preference is not an intrinsic characteristic of the transcriptase, but is due to a temperature-dependent inhibition of transcription at high core concentrations

[Evaluation of modern epizootic activity of natural tularemia foci in Voronezh region using immune-serological and molecular-genetic study of main carriers of the disease].

Science.gov (United States)

Meshcheriakova, I S; Trankvilevskiĭ, D V; Kvasov, D A; Mikhaĭlova, T V; Kormilitsina, M I; Demidova, T N; Stepkin, Iu I; Zhukov, V I

2015-01-01

Improvement of monitoring and prognosis of epidemic manifestations of natural foci of tularemia on the territory of Voronezh region using immune-serological and molecular-genetic study of main carriers of the disease. 539 small mammals captured during summer period of 2011 in 4 districts of North-Eastern part of Voronezh region were studied. Animal organs were studied by serologic (search for Francisella tularensis antigens) and molecular-biologic (detection of F. tularensis DNA) methods. Tularemia antigen was detected using passive hemagglutination reaction (PHAR) with erythrocytic tularemia immunoglobulin diagnosticum. Real-time polymerase chain reaction (RT-PCR) was applied for detection of tularemia causative agent DNA. Complex study revealed epizootic activity of natural foci of tularemia in the examined territory. F. tularensis antigen and/or DNA were detected in 82 objects (15.2%). Use of RT-PCR allowed to additionally detect samples with relatively low content of F. tularensis DNA substrate, when antigen was not detected in samples. High sensitivity and specificity of the RT-PCR was ensured by inclusion of specific probes (tu14-PR2 and ISFTu2P). The results obtained give evidence on functioning and epizootic activity of natural foci of tularemia in Voronezh region that requires constant monitoring of the territory and prophylaxis measures, first of all vaccination of risk groups by live tularemia vaccine.

Cuticles of European and American lobsters harbor diverse bacterial species and differ in disease susceptibility.

Science.gov (United States)

Whitten, Miranda M A; Davies, Charlotte E; Kim, Anita; Tlusty, Michael; Wootton, Emma C; Chistoserdov, Andrei; Rowley, Andrew F

2014-06-01

Diseases of lobster shells have a significant impact on fishing industries but the risk of disease transmission between different lobster species has yet to be properly investigated. This study compared bacterial biofilm communities from American (Homarus americanus) and European lobsters (H. gammarus), to assess both healthy cuticle and diseased cuticle during lesion formation. Culture-independent molecular techniques revealed diversity in the bacterial communities of cuticle biofilms both within and between the two lobster species, and identified three bacterial genera associated with shell lesions plus two putative beneficial bacterial species (detected exclusively in healthy cuticle or healing damaged cuticle). In an experimental aquarium shared between American and European lobsters, heterospecific transmission of potentially pathogenic bacteria appeared to be very limited; however, the claws of European lobsters were more likely to develop lesions when reared in the presence of American lobsters. Aquarium biofilms were also examined but revealed no candidate pathogens for environmental transmission. Aquimarina sp. 'homaria' (a potential pathogen associated with a severe epizootic form of shell disease) was detected at a much higher prevalence among American than European lobsters, but its presence correlated more with exacerbation of existing lesions rather than with lesion initiation. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Molecular epidemiology of Epizootic haematopoietic necrosis virus (EHNV).

Science.gov (United States)

Hick, Paul M; Subramaniam, Kuttichantran; Thompson, Patrick M; Waltzek, Thomas B; Becker, Joy A; Whittington, Richard J

2017-11-01

Low genetic diversity of Epizootic haematopoietic necrosis virus (EHNV) was determined for the complete genome of 16 isolates spanning the natural range of hosts, geography and time since the first outbreaks of disease. Genomes ranged from 125,591-127,487 nucleotides with 97.47% pairwise identity and 106-109 genes. All isolates shared 101 core genes with 121 potential genes predicted within the pan-genome of this collection. There was high conservation within 90,181 nucleotides of the core genes with isolates separated by average genetic distance of 3.43 × 10 -4 substitutions per site. Evolutionary analysis of the core genome strongly supported historical epidemiological evidence of iatrogenic spread of EHNV to naïve hosts and establishment of endemic status in discrete ecological niches. There was no evidence of structural genome reorganization, however, the complement of non-core genes and variation in repeat elements enabled fine scale molecular epidemiological investigation of this unpredictable pathogen of fish. Copyright © 2017 Elsevier Inc. All rights reserved.

1995 epizootic of vesicular stomatitis (New Jersey serotype) in the western United States: an entomologic perspective.

Science.gov (United States)

Schmidtmann, E T; Tabachnick, W J; Hunt, G J; Thompson, L H; Hurd, H S

1999-01-01

Entomologic and epizootic data are reviewed concerning the potential for transmission of vesicular stomatitis (VS) virus by insects, including field data from case-positive premises in New Mexico and Colorado during the 1995 outbreak of the New Jersey serotype (VSNJ). As with previous outbreaks of VSNJ in the western United States, the 1995 epizootic illustrated that risk of exposure is seasonal, increasing during warm weather and decreasing with onset of cool weather; virus activity spread from south to north along river valleys of the southwestern and Rocky Mountain states; clinical disease was detected most commonly in horses, but also occurred in cattle and 1 llama; and most infections were subclinical. Overall, 367 case-positive premises were identified during the 1995 outbreak, with foci of virus activity along the Rio Grande River south of Albuquerque, NM, in southwestern Colorado, and along the Colorado River near Grand Junction, CO. The establishment of a 16-km (10-mile) radius zone of restricted animal movement around confirmed positive premises, along with imposition of state and international embargoes, created economic hardship for livestock owners and producers. The importance of defining the role of blood-feeding insects as biological vectors of VSNJ virus relative to risk factors that promote high levels of insect transmission, such as the presence of livestock along western river valleys, blood feeding activity, and frequent transport of animals for recreational purposes, is emphasized as a basis for developing effective disease management.

Epizootic of Yersinia pseudotuberculosis in a wildlife park.

Science.gov (United States)

Welsh, R D; Ely, R W; Holland, R J

1992-07-01

An epizootic attributable to Yersinia pseudotuberculosis infection was confirmed in captive ruminants in a wildlife park by microbiologic and histologic findings. An epornitic of Y pseudotuberculosis infection was identified at the same period in a vicinity near the ruminant deaths. Yersinia pseudotuberculosis can infect human beings and cause acute enteritis and mesenteric lymphadenitis. People in contact with infected animals should use extreme caution and use good sanitary precautions to preclude transmission of this agent.

Structured decision making for managing pneumonia epizootics in bighorn sheep

Science.gov (United States)

Sells, Sarah N.; Mitchell, Michael S.; Edwards, Victoria L.; Gude, Justin A.; Anderson, Neil J.

2016-01-01

Good decision-making is essential to conserving wildlife populations. Although there may be multiple ways to address a problem, perfect solutions rarely exist. Managers are therefore tasked with identifying decisions that will best achieve desired outcomes. Structured decision making (SDM) is a method of decision analysis used to identify the most effective, efficient, and realistic decisions while accounting for values and priorities of the decision maker. The stepwise process includes identifying the management problem, defining objectives for solving the problem, developing alternative approaches to achieve the objectives, and formally evaluating which alternative is most likely to accomplish the objectives. The SDM process can be more effective than informal decision-making because it provides a transparent way to quantitatively evaluate decisions for addressing multiple management objectives while incorporating science, uncertainty, and risk tolerance. To illustrate the application of this process to a management need, we present an SDM-based decision tool developed to identify optimal decisions for proactively managing risk of pneumonia epizootics in bighorn sheep (Ovis canadensis) in Montana. Pneumonia epizootics are a major challenge for managers due to long-term impacts to herds, epistemic uncertainty in timing and location of future epizootics, and consequent difficulty knowing how or when to manage risk. The decision tool facilitates analysis of alternative decisions for how to manage herds based on predictions from a risk model, herd-specific objectives, and predicted costs and benefits of each alternative. Decision analyses for 2 example herds revealed that meeting management objectives necessitates specific approaches unique to each herd. The analyses showed how and under what circumstances the alternatives are optimal compared to other approaches and current management. Managers can be confident that these decisions are effective, efficient, and

Antigenic profile of African horse sickness virus serotype 4 VP5 and identification of a neutralizing epitope shared with bluetongue virus and epizootic hemorrhagic disease virus

DEFF Research Database (Denmark)

Martinez-Torrecuadrada, J.L.; Langeveld, J.P.M.; Venteo, A.

1999-01-01

African horse sickness virus (AHSV) causes a fatal disease in horses. The virus capsid is composed of a double protein layer, the outermost of which is formed by two proteins: VP2 and VP5. VP2 is known to determine the serotype of the virus and to contain the neutralizing epitopes. The biological...... in a plaque reduction assay were generated. To dissect the antigenic structure of AHSV VP5, the protein was cloned in Escherichia coil using the pET3 system. The immunoreactivity of both MAbs, and horse and rabbit polyclonal antisera, with 17 overlapping fragments from VP5 was analyzed. The most....... Neutralizing epitopes were defined at positions 85-92 (PDPLSPGE) for MAb 10AE12 and at 179-185 (EEDLRTR) for MAb 10AC6. Epitope 10AE12 is highly conserved between the different orbiviruses. MAb 10AE12 was able to recognize bluetongue virus VP5 and epizootic hemorrhagic disease virus VP5 by several techniques...

Dynamics of epizootic hemorrhagic disease virus infection within the vector, Culicoides sonorensis (Diptera: Ceratopogonidae.

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Mary K Mills

Full Text Available Culicoides sonorensis biting midges are confirmed vectors of epizootic hemorrhagic disease virus (EHDV, which causes mortality in white-tailed deer and ruminant populations. Currently, of the seven EHDV serotypes, only 1, 2, and 6 are detected in the USA, and very few studies have focused on the infection time course of these serotypes within the midge. The objective of this current research was to characterize EHDV-2 infection within the midge by measuring infection prevalence, virus dissemination, and viral load over the course of infection. Midges were fed a blood meal containing 106.9 PFU/ml EHDV-2, collected every 12 h from 0-2 days post feeding (dpf and daily from 3-10 dpf, and cohorts of 20 C. sonorensis were processed using techniques that assessed EHDV infection and dissemination. Cytopathic effect assays and quantitative (qPCR were used to determine infection prevalence, revealing a 50% infection rate by 10 dpf using both methods. Using immunohistochemistry, EHDV-2 infection was detectable at 5 dpf, and shown to disseminate from the midgut to other tissues, including fat body, eyes, and salivary glands by 5 dpf. Stain intensity increased from 5-8 dpf, indicating replication of EHDV-2 in secondary infection sites after dissemination. This finding is also supported by trends in viral load over time as determined by plaque assays and qPCR. An increase in titer between 4-5 dpf correlated with viral replication in the midgut as seen with staining at day 5, while the subsequent gradual increase in viral load from 8-10 dpf suggested viral replication in midges with disseminated infection. Overall, the data presented herein suggest that EHDV-2 disseminates via the hemolymph to secondary infection sites throughout the midge and demonstrate a high potential for transmission at five days at 25°C after an infective blood-meal.

[Molecular-biologic analysis of avian influenza virus isolates which caused epizootics on the south of West Siberia and in Crimea].

Science.gov (United States)

Onishchenko, G G; Berezhnov, S P; Shestopalov, A M; Alekseev, A Iu; Ternovoĭ, V A; Khaĭtovich, A B; Kroviakova, M T; Netesov, S V; Drozdov, I G

2007-01-01

The objective of the study was to determine reasons of poultry deaths in Crimea Republic in December 2005 as well as isolation, identification, and comparative analysis of pathogens, which caused epizootics in Siberia and Crimea. During epizootic in poultry in North-East Crimea highly pathogenic avian influenza virus H5N1 was isolated. Phylogenetic analysis of RNA sequences revealed that they belong to one big cluster. Isolated strain was close to viruses, which caused epizootic in July-August 2005 in the south of West Siberia. Conclusion about the high importance of the south of West Siberia in spreading of highly pathogenic influenza viruses H5N1 in Eurasia was made.

[IMPACT OF CASPIAN SEA LEVEL FLUCTUATIONS ON THE EPIZOOTIC ACTIVITY OF THE CASPIAN SANDY NATURAL PLAGUE FOCUS].

Science.gov (United States)

Popov, N V; Udovikov, A I; Eroshenko, G A; Karavaeva, T B; Yakovlev, S A; Porshakov, A M; Zenkevich, E S; Kutyrev, V V

2016-01-01

There is evidence that in 1923-2014 the sharp aggravations of the epizootic situation of plague in the area of its Caspian sandy natural focus after long interepizootic periods are in time with the ups of the Caspian Sea in the extrema of 11-year solar cycles. There were cases of multiple manifestations of plague in the same areas in the epizootic cycles of 1946-1954, 1979-1996, 2001, and 2013-2014. The paper considers the possible role of amebae of the genus Acanthamoeba and nematodes, the representatives of the orders Rhabditida and Tylenchida in the microfocal pattern of plague manifestations.

Using animal performance data to evidence the under-reporting of case herds during an epizootic: application to an outbreak of bluetongue in cattle.

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Simon Nusinovici

Full Text Available Following the emergence of the Bluetongue virus serotype 8 (BTV-8 in France in 2006, a surveillance system (both passive and active was implemented to detect and follow precociously the progression of the epizootic wave. This system did not allow a precise estimation of the extent of the epizootic. Infection by BTV-8 is associated with a decrease of fertility. The objective of this study was to evaluate whether a decrease in fertility can be used to evidence the under-reporting of cases during an epizootic and to quantify to what extent non-reported cases contribute to the total burden of the epizootic. The cow fertility in herds in the outbreak area (reported or not was monitored around the date of clinical signs. A geostatistical interpolation method was used to estimate a date of clinical signs for non-reported herds. This interpolation was based on the spatiotemporal dynamic of confirmed case herds reported in 2007. Decreases in fertility were evidenced for both types of herds around the date of clinical signs. In non-reported herds, the decrease fertility was large (60% of the effect in reported herds, suggesting that some of these herds have been infected by the virus during 2007. Production losses in non-reported infected herds could thus contribute to an important part of the total burden of the epizootic. Overall, results indicate that performance data can be used to evidence the under-reporting during an epizootic. This approach could be generalized to pathogens that affect cattle's performance, including zoonotic agents such as Coxiella burnetii or Rift Valley fever virus.

Identification of Wild Boar-Habitat Epidemiologic Cycle in African Swine Fever Epizootic.

Science.gov (United States)

Chenais, Erika; Ståhl, Karl; Guberti, Vittorio; Depner, Klaus

2018-04-01

The African swine fever epizootic in central and eastern European Union member states has a newly identified component involving virus transmission by wild boar and virus survival in the environment. Insights led to an update of the 3 accepted African swine fever transmission models to include a fourth cycle: wild boar-habitat.

Identification of Wild Boar–Habitat Epidemiologic Cycle in African Swine Fever Epizootic

Science.gov (United States)

Ståhl, Karl; Guberti, Vittorio; Depner, Klaus

2018-01-01

The African swine fever epizootic in central and eastern European Union member states has a newly identified component involving virus transmission by wild boar and virus survival in the environment. Insights led to an update of the 3 accepted African swine fever transmission models to include a fourth cycle: wild boar–habitat. PMID:29553337

[Epizootic and epidemic manifestation of natural foci of tularemia in Moscow region (1965-2013)].

Science.gov (United States)

Demidova, T N; Popov, V P; Polukhina, A N; Orlov, D S; Mescheryakova, I S; Mikhailova, T V

2015-01-01

Detection of contemporary features of tularemia focimanifestations, determination of territories of high epidemic risk in various landscape zones and creation of a map of foci territories of Moscow Region for isolation of tularemia infectious agent cultures and registered human morbidity for justified planning of prophylaxis measures. Report materials of epizootologic examinations of natural foci for 1965-2013, 156 maps of epidemiologic examination of cases of human infection with tularemia, results of studies of casting of predatory birds and dung of predatory mammals were used. Registered morbidity and isolation of tularemia infectious agent cultures from 1965 to date were applied to an electronic map of Moscow Region by sign method using modern. GIS-technologies (MapInfo 10.5 program). Electronic maps Ingit at 1:200,000 scale, as well as Google Earth program were used to search for base points. Analysis of morbidity has revealed structure change in human tularemia morbidity--an increase of the fraction of urban population and a decrease of the fraction of patients among rural inhabitants, unimmunized against this infection are mostly ill. The presence of DNA of tularemia causative agent in biological objects in the complex with serologic and bacteriological studies was shown to allow to detect flaccid epizootics even at low numbers of rodents. Cartographic reflection of registered morbidity and isolation of tularemia infectious agent cultures allowed to show territories with various degrees of epizootic activity and epidemic manifestation. Positive results of serologic and molecular-genetic studies of environmental objects gives evident on epizootic activity and constant risk of aggravation of epidemic situation for this infection.

Epizootic rabbit enteropathy inoculum (TEC4): antibiograms and antibiotic fractionation.

Science.gov (United States)

Huybens, Nathalie; Houeix, Julien; Licois, Dominique; Mainil, Jacques; Marlier, Didier

2011-01-01

Epizootic rabbit enteropathy (ERE) emerged and spread in Europe within the last 13 years causing major economical loss. The aims of the study was to evaluate antibiograms of TEC4, an inoculum composed of an extract of intestinal content of affected rabbits, and to test the potential of different antibiotic-based TEC4 fractions to reproduce the disease. Twenty nine different antibiotic discs were incubated for determining bacteria resistance. In a complementary study, nine tubes of liquid medium were inoculated with TEC4, incubated and added individually with amoxicillin/clavulanic acid, bacitracin, ceftiofur, doxycycline, novobiocin, streptomycyin, tylosin, vancomycin and 0.9% saline solution as control. The content of each tube was washed by centrifugation and suspended in saline. The three most effective antibiotics are florfenicol, amoxycillin/clavulanic acid and tylosin. A high concentration of Clostridium sordelli and Bacillus firmus were isolated in all fractions. Species never cultured from TEC4 were identified as Fusobacterium necrogenes (in vancomycin fraction), Cellulomonas sp (in novobiocin fraction) and Bacteroides distasonis (in doxycycline fraction). The ERE was reproduced when bacitracin, doxycycline and 0.9% fractions were inoculated. Rabbits showed ERE clinical signs with the specific drop in daily weight gain.

Avian disease at the Salton Sea

Science.gov (United States)

Friend, M.

2002-01-01

A review of existing records and the scientific literature was conducted for occurrences of avian diseases affecting free-ranging avifauna within the Salton Sea ecosystem. The period for evaluation was 1907 through 1999. Records of the U.S. Department of Agriculture, Bureau of Biological Survey and the scientific literature were the data sources for the period of 1907a??1939. The narrative reports of the U.S. Fish and Wildlife Service's Sonny Bono National Wildlife Refuge Complex and the epizootic database of the U.S. Geological Survey's National Wildlife Health Center were the primary data sources for the remainder of the evaluation. The pattern of avian disease at the Salton Sea has changed greatly over time. Relative to past decades, there was a greater frequency of major outbreaks of avian disease at the Salton Sea during the 1990s than in previous decades, a greater variety of disease agents causing epizootics, and apparent chronic increases in the attrition of birds from disease. Avian mortality was high for about a decade beginning during the mid-1920s, diminished substantially by the 1940s and was at low to moderate levels until the 1990s when it reached the highest levels reported. Avian botulism (Clostridium botulinum type C) was the only major cause of avian disease until 1979 when the first major epizootic of avian cholera (Pasteurella multocidia) was documented. Waterfowl and shorebirds were the primary species affected by avian botulism. A broader spectrum of species have been killed by avian cholera but waterfowl have suffered the greatest losses. Avian cholera reappeared in 1983 and has joined avian botulism as a recurring cause of avian mortality. In 1989, avian salmonellosis (Salmonella typhimurium) was first diagnosed as a major cause of avian disease within the Salton Sea ecosystem and has since reappeared several times, primarily among cattle egrets (Bubulcus ibis). The largest loss from a single epizootic occurred in 1992, when an estimated

Beak deformities in Northwestern Crows: Evidence of a multispecies epizootic

Science.gov (United States)

Van Hemert, Caroline; Handel, Colleen M.

2010-01-01

Beak abnormalities are rare among adult birds and, typically, are not widespread in a given population, within a region, or across multiple species. A high concentration of beak deformities was recently documented in Black-capped Chickadees (Poecile atricapillus) and other resident avian species in Alaska. We describe a parallel condition in Northwestern Crows (Corvus caurinus) that signals the emergence of a multispecies epizootic. On the basis of 186 Northwestern Crows captured at six sites in Alaska during 2007 and 2008, we estimated the prevalence of beak deformities in adults to be 16.9 ± 5.3%, the highest rate of gross deformities ever recorded in a wild bird population. Prevalence varied among sites and was as high as 36% on the Kenai Peninsula, which suggests possible epizootic clusters. We also documented beak abnormalities in an additional 148 Northwestern Crows in south-central and southeastern Alaska and in 64 crows near Vancouver, British Columbia, and Puget Sound, Washington, a region where both Northwestern Crows and American Crows (C. brachyrhynchos) occur. The increase in frequency and distribution of crows observed with abnormal beaks throughout the Pacific Northwest since the late 1990s indicates a geographic expansion of this problem. Affected crows exhibited elongated and often crossed beaks that were morphologically similar to deformities documented in Black-capped Chickadees and other species in Alaska over approximately the same period. Additional research is needed to determine the etiology and potential adverse effects on bird populations affected by this disorder.

Analysis of spatial dynamic of epizootic process of bluetongue and its risk factors.

Science.gov (United States)

Bouchemla, Fayssal; Popova, Olga Mikhailovna; Agoltsov, Valerey Alexandrovich

2017-10-01

The study was undertaken to find out the spatial dynamic occurrence and patterns of the global spread of bluetongue (BT) disease for the period from 1996 to 2016, as well as the assessment of the risk of occurrence and its spread in 2017-2018. Outbreaks (serum samples were collected from clinically healthy as well as suspected animals in infected points) were confirmed and reported officially by veterinary departments which represent different geographical regions in the world to World Organization for Animal Health. These reports explained that ELISA and polymerase chain reaction were used to identify the BT disease, taking in the account number of infected, dead animals, and focus of BT infection in all susceptible animals from 1996 to 2016. Once conventional statistical population was defined (an observational study), we had classified data as well as possible to answer to our aim, using descriptive statistics methods, including the test of the relationship between different epizootiological indicators. The spatial dynamic study of BT's occurrence and its spread in the world over the two past decades was presented by different epizootic indicators. The given analysis includes assessment and measurement of risk factors. It was built too, regression models, and allowed to put different forecasts on the different epizootic indicators in the years 2017-2018 by the extrapolation method. We had also determined that, in 2017, BT continues to spread with the total expectancy of 3.4 focus of infection (number of diseased animals in a single unfavorable point) and mortality of about 26 %; these rates tend to decrease in 2018. At abused points by BT, up to 78.4% of animals are mixed (more than one type) and in 21.6% - uniform. By this way, the relative risk of the incidence of appearance-abused points in mixed households has 3.64, which might be considered higher for the BT dissemination. Moreover, between the enzootic index and other epizootiological indicators had

Analysis of spatial dynamic of epizootic process of bluetongue and its risk factors

Directory of Open Access Journals (Sweden)

Fayssal Bouchemla

2017-10-01

Full Text Available Aim: The study was undertaken to find out the spatial dynamic occurrence and patterns of the global spread of bluetongue (BT disease for the period from 1996 to 2016, as well as the assessment of the risk of occurrence and its spread in 2017-2018. Materials and Methods: Outbreaks (serum samples were collected from clinically healthy as well as suspected animals in infected points were confirmed and reported officially by veterinary departments which represent different geographical regions in the world to World Organization for Animal Health. These reports explained that ELISA and polymerase chain reaction were used to identify the BT disease, taking in the account number of infected, dead animals, and focus of BT infection in all susceptible animals from 1996 to 2016. Once conventional statistical population was defined (an observational study, we had classified data as well as possible to answer to our aim, using descriptive statistics methods, including the test of the relationship between different epizootiological indicators. Results: The spatial dynamic study of BT's occurrence and its spread in the world over the two past decades was presented by different epizootic indicators. The given analysis includes assessment and measurement of risk factors. It was built too, regression models, and allowed to put different forecasts on the different epizootic indicators in the years 2017-2018 by the extrapolation method. We had also determined that, in 2017, BT continues to spread with the total expectancy of 3.4 focus of infection (number of diseased animals in a single unfavorable point and mortality of about 26 %; these rates tend to decrease in 2018. At abused points by BT, up to 78.4% of animals are mixed (more than one type and in 21.6% - uniform. By this way, the relative risk of the incidence of appearance-abused points in mixed households has 3.64, which might be considered higher for the BT dissemination. Moreover, between the enzootic

African horse sickness: The potential for an outbreak in disease-free regions and current disease control and elimination techniques.

Science.gov (United States)

Robin, M; Page, P; Archer, D; Baylis, M

2016-09-01

African horse sickness (AHS) is an arboviral disease of equids transmitted by Culicoides biting midges. The virus is endemic in parts of sub-Saharan Africa and official AHS disease-free status can be obtained from the World Organization for Animal Health on fulfilment of a number of criteria. AHS is associated with case fatality rates of up to 95%, making an outbreak among naïve horses both a welfare and economic disaster. The worldwide distributions of similar vector-borne diseases (particularly bluetongue disease of ruminants) are changing rapidly, probably due to a combination of globalisation and climate change. There is extensive evidence that the requisite conditions for an AHS epizootic currently exist in disease-free countries. In particular, although the stringent regulations enforced upon competition horses make them extremely unlikely to redistribute the virus, there are great concerns over the effects of illegal equid movement. An outbreak of AHS in a disease free region would have catastrophic effects on equine welfare and industry, particularly for international events such as the Olympic Games. While many regions have contingency plans in place to manage an outbreak of AHS, further research is urgently required if the equine industry is to avoid or effectively contain an AHS epizootic in disease-free regions. This review describes the key aspects of AHS as a global issue and discusses the evidence supporting concerns that an epizootic may occur in AHS free countries, the planned government responses, and the roles and responsibilities of equine veterinarians. © 2016 EVJ Ltd.

A Quantitative Polymerase Chain Reaction Assay for the Detection and Quantification of Epizootic Epitheliotropic Disease Virus (EEDV; Salmonid Herpesvirus 3).

Science.gov (United States)

Glenney, Gavin W; Barbash, Patricia A; Coll, John A

2016-03-01

Epizootic epitheliotropic disease virus (EEDV; salmonid herpesvirus [SalHV3]; family Alloherpesviridae) causes a systemic disease of juvenile and yearling Lake Trout Salvelinus namaycush. No cell lines are currently available for the culture and propagation of EEDV, so primary diagnosis is limited to PCR and electron microscopy. To better understand the pervasiveness of EEDV (carrier or latent state of infection) in domesticated and wild Lake Trout populations, we developed a sensitive TaqMan quantitative PCR (qPCR) assay to detect the presence of the EEDV terminase gene in Lake Trout tissues. This assay was able to detect a linear standard curve over nine logs of plasmid dilution and was sensitive enough to detect single-digit copies of EEDV. The efficiency of the PCR assay was 99.4 ± 0.06% (mean ± SD), with a 95% confidence limit of 0.0296 (R(2) = 0.994). Methods were successfully applied to collect preliminary data from a number of species and water bodies in the states of Pennsylvania, New York, and Vermont, indicating that EEDV is more common in wild fish than previously known. In addition, through the development of this qPCR assay, we detected EEDV in a new salmonid species, the Cisco Coregonus artedi. The qPCR assay was unexpectedly able to detect two additional herpesviruses, the Atlantic Salmon papillomatosis virus (ASPV; SalHV4) and the Namaycush herpesvirus (NamHV; SalHV5), which both share high sequence identity with the EEDV terminase gene. With these unexpected findings, we subsequently designed three primer sets to confirm initial TaqMan qPCR assay positives and to differentiate among EEDV, ASPV, and NamHV by detecting the glycoprotein genes via SYBR Green qPCR. Received April 20, 2015; accepted November 10, 2015.

Microbial Degradation of Lobster Shells to Extract Chitin Derivatives for Plant Disease Management

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Gayathri Ilangumaran

2017-05-01

Full Text Available Biodegradation of lobster shells by chitinolytic microorganisms are an environment safe approach to utilize lobster processing wastes for chitin derivation. In this study, we report degradation activities of two microbes, “S223” and “S224” isolated from soil samples that had the highest rate of deproteinization, demineralization and chitinolysis among ten microorganisms screened. Isolates S223 and S224 had 27.3 and 103.8 protease units mg-1 protein and 12.3 and 11.2 μg ml-1 of calcium in their samples, respectively, after 1 week of incubation with raw lobster shells. Further, S223 contained 23.8 μg ml-1 of N-Acetylglucosamine on day 3, while S224 had 27.3 μg ml-1 on day 7 of incubation with chitin. Morphological observations and 16S rDNA sequencing suggested both the isolates were Streptomyces. The culture conditions were optimized for efficient degradation of lobster shells and chitinase (∼30 kDa was purified from crude extract by affinity chromatography. The digested lobster shell extracts induced disease resistance in Arabidopsis by induction of defense related genes (PR1 > 500-fold, PDF1.2 > 40-fold upon Pseudomonas syringae and Botrytis cinerea infection. The study suggests that soil microbes aid in sustainable bioconversion of lobster shells and extraction of chitin derivatives that could be applied in plant protection.

High probability of avian influenza virus (H7N7) transmission from poultry to humans active in disease control on infected farms

NARCIS (Netherlands)

M.E.H. Bos (Marian); D.E. te Beest (Dennis); M. van Boven (Michiel); M.R.D.R.B. van Holle; A. Meijer (Adam); A. Bosman (Arnold); Y.M. Mulder (Yonne); M.P.G. Koopmans D.V.M. (Marion); A. Stegeman (Arjan)

2010-01-01

textabstractAn epizootic of avian influenza (H7N7) caused a large number of human infections in The Netherlands in 2003. We used data from this epizootic to estimate infection probabilities for persons involved in disease control on infected farms. Analyses were based on databases containing

Denaturing gradient gel electrophoresis (DGGE as a powerful novel alternative for differentiation of epizootic ISA virus variants.

Directory of Open Access Journals (Sweden)

Marisela Carmona

Full Text Available Infectious Salmon Anemia is a devastating disease critically affecting world-wide salmon production. Chile has been particularly stricken by this disease which in all cases has been directly related with its causative agent, a novel orthomyxovirus which presents specific and distinctive infective features. Among these, two molecular markers have been directly associated with pathogenicity in two of the eight RNA sub genomic coding units of the virus: an insertion hot spot region present in viral segment 5 and a Highly Polymorphic Region (HPR located in viral segment 6. Here we report the successful adaptation of a PCR-dependent denaturing gel electrophoresis technique (DGGE, which enables differentiation of selected reported HPR epizootic variants detected in Chile. At the same time, the technique allows us to distinguish one nucleotide differences in sequences associated with the intriguing, and still not well-understood, insertion events which tend to occur on RNA Segment 5. Thus, the versatility of the technique opens new opportunities for improved understanding of the complex biology of all ISA variants as well as possible applications to other highly variable pathogens.

Changes in cecal microbiota and mucosal gene expression revealed new aspects of epizootic rabbit enteropathy.

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Christine Bäuerl

Full Text Available Epizootic Rabbit Enteropathy (ERE is a severe disease of unknown aetiology that mainly affects post-weaning animals. Its incidence can be prevented by antibiotic treatment suggesting that bacterial elements are crucial for the development of the disease. Microbial dynamics and host responses during the disease were studied. Cecal microbiota was characterized in three rabbit groups (ERE-affected, healthy and healthy pretreated with antibiotics, followed by transcriptional analysis of cytokines and mucins in the cecal mucosa and vermix by q-rtPCR. In healthy animals, cecal microbiota with or without antibiotic pretreatment was very similar and dominated by Alistipes and Ruminococcus. Proportions of both genera decreased in ERE rabbits whereas Bacteroides, Akkermansia and Rikenella increased, as well as Clostridium, γ-Proteobacteria and other opportunistic and pathogenic species. The ERE group displayed remarkable dysbiosis and reduced taxonomic diversity. Transcription rate of mucins and inflammatory cytokines was very high in ERE rabbits, except IL-2, and its analysis revealed the existence of two clearly different gene expression patterns corresponding to Inflammatory and (mucin Secretory Profiles. Furthermore, these profiles were associated to different bacterial species, suggesting that they may correspond to different stages of the disease. Other data obtained in this work reinforced the notion that ERE morbidity and mortality is possibly caused by an overgrowth of different pathogens in the gut of animals whose immune defence mechanisms seem not to be adequately responding.

Respiratory disease, behavior, and survival of mountain goat kids

Science.gov (United States)

Blanchong, Julie A.; Anderson, Christopher A.; Clark, Nicholas J.; Klaver, Robert W.; Plummer, Paul J.; Cox, Mike; Mcadoo, Caleb; Wolff, Peregrine L.

2018-01-01

Bacterial pneumonia is a threat to bighorn sheep (Ovis canadensis) populations. Bighorn sheep in the East Humboldt Mountain Range (EHR), Nevada, USA, experienced a pneumonia epizootic in 2009–2010. Testing of mountain goats (Oreamnos americanus) that were captured or found dead on this range during and after the epizootic detected bacteria commonly associated with bighorn sheep pneumonia die‐offs. Additionally, in years subsequent to the bighorn sheep epizootic, the mountain goat population had low kid:adult ratios, a common outcome for bighorn sheep populations that have experienced a pneumonia epizootic. We hypothesized that pneumonia was present and negatively affecting mountain goat kids in the EHR. From June–August 2013–2015, we attempted to observe mountain goat kids with marked adult females in the EHR at least once per week to document signs of respiratory disease; identify associations between respiratory disease, activity levels, and subsequent disappearance (i.e., death); and estimate weekly survival. Each time we observed a kid with a marked adult female, we recorded any signs of respiratory disease and collected behavior data that we fit to a 3‐state discrete hidden Markov model (HMM) to predict a kid's state (active vs. sedentary) and its probability of disappearing. We first observed clinical signs of respiratory disease in kids in late July–early August each summer. We observed 8 of 31 kids with marked adult females with signs of respiratory disease on 13 occasions. On 11 of these occasions, the HMM predicted that kids were in the sedentary state, which was associated with increased probability of subsequent death. We estimated overall probability of kid survival from June–August to be 0.19 (95% CI = 0.08–0.38), which was lower than has been reported in other mountain goat populations. We concluded that respiratory disease was present in the mountain goat kids in the EHR and negatively affected their activity levels and survival

Plague cycles in two rodent species from China: Dry years might provide context for epizootics in wet years

Science.gov (United States)

Eads, David A.; Biggins, Dean E.; Xu, Lei; Liu, Qiyong

2016-01-01

Plague, a rodent-associated, flea-borne zoonosis, is one of the most notorious diseases in history. Rates of plague transmission can increase when fleas are abundant. Fleas commonly desiccate and die when reared under dry conditions in laboratories, suggesting fleas will be suppressed during droughts in the wild, thus reducing the rate at which plague spreads among hosts. In contrast, fleas might increase in abundance when precipitation is plentiful, producing epizootic outbreaks during wet years. We tested these hypotheses using a 27-yr data set from two rodents in Inner Mongolia, China: Mongolian gerbils (Meriones unguiculatus) and Daurian ground squirrels (Spermophilus dauricus). For both species of rodents, fleas were most abundant during years preceded by dry growing seasons. For gerbils, the prevalence of plague increased during wet years preceded by dry growing seasons. If precipitation is scarce during the primary growing season, succulent plants decline in abundance and, consequently, herbivorous rodents can suffer declines in body condition. Fleas produce more offspring and better survive when parasitizing food-limited hosts, because starving animals tend to exhibit inefficient behavioral and immunological defenses against fleas. Further, rodent burrows might buffer fleas from xeric conditions aboveground during dry years. After a dry year, fleas might be abundant due to the preceding drought, and if precipitation and succulent plants become more plentiful, rodents could increase in density, thereby creating connectivity that facilitates the spread of plague. Moreover, in wet years, mild temperatures might increase the efficiency at which fleas transmit the plague bacterium, while also helping fleas to survive as they quest among hosts. In this way, dry years could provide context for epizootics of plague in wet years.

Bovine epizootic encephalomyelitis caused by Akabane virus in southern Japan

Directory of Open Access Journals (Sweden)

Tanaka Shogo

2008-06-01

from overseas in the summer of 2006 and caused an unprecedented epizootic of encephalomyelitis mainly in susceptible calves. It will be necessary to reconsider the vaccine strategy to control the disease effectually.

An Ichthyophonus hoferi epizootic in herring in the North Sea, the Skagerrak, the Kattegat and the Baltic Sea

DEFF Research Database (Denmark)

Mellergaard, Stig; Spanggaard, Bettina

1997-01-01

An epizootic caused by the internal parasite Ichthyophonus hoferi in herring Clupea harengus was recorded from 1991 to 1993 in the waters around Denmark. A surveillance programme from research vessels and commercial fishing boats was conducted in the North Sea, Skagerrak, Kattegat and Baltic Sea...

A protozoal-associated epizootic impacting marine wildlife: mass-mortality of southern sea otters (Enhydra lutris nereis) due to Sarcocystis neurona infection.

Science.gov (United States)

Miller, Melissa A; Conrad, Patricia A; Harris, Michael; Hatfield, Brian; Langlois, Gregg; Jessup, David A; Magargal, Spencer L; Packham, Andrea E; Toy-Choutka, Sharon; Melli, Ann C; Murray, Michael A; Gulland, Frances M; Grigg, Michael E

2010-09-20

During April 2004, 40 sick and dead southern sea otters (Enhydra lutris nereis) were recovered over 18km of coastline near Morro Bay, California. This event represented the single largest monthly spike in mortality ever recorded during 30 years of southern sea otter stranding data collection. Because of the point-source nature of the event and clinical signs consistent with severe, acute neurological disease, exposure to a chemical or marine toxin was initially considered. However, detailed postmortem examinations revealed lesions consistent with an infectious etiology, and further investigation confirmed the protozoan parasite Sarcocystis neurona as the underlying cause. Tissues from 94% of examined otters were PCR-positive for S. neurona, based on DNA amplification and sequencing at the ITS-1 locus, and 100% of tested animals (n=14) had elevated IgM and IgG titers to S. neurona. Evidence to support the point-source character of this event include the striking spatial and temporal clustering of cases and detection of high concentrations of anti-S. neurona IgM in serum of stranded animals. Concurrent exposure to the marine biotoxin domoic acid may have enhanced susceptibility of affected otters to S. neurona and exacerbated the neurological signs exhibited by stranded animals. Other factors that may have contributed to the severity of this epizootic include a large rainstorm that preceded the event and an abundance of razor clams near local beaches, attracting numerous otters close to shore within the affected area. This is the first report of a localized epizootic in marine wildlife caused by apicomplexan protozoa.

Border Disease Virus among Chamois, Spain

Science.gov (United States)

Rosell, Rosa; Cabezón, Oscar; Mentaberre, Gregorio; Casas, Encarna; Velarde, Roser; Lavín, Santiago

2009-01-01

Approximately 3,000 Pyrenean chamois (Rupicapra pyrenaica pyrenaica) died in northeastern Spain during 2005–2007. Border disease virus infection was identified by reverse transcription–PCR and sequencing analysis. These results implicate this virus as the primary cause of death, similar to findings in the previous epizootic in 2001. PMID:19239761

Models of marine molluscan diseases: Trends and challenges.

Science.gov (United States)

Powell, Eric N; Hofmann, Eileen E

2015-10-01

Disease effects on host population dynamics and the transmission of pathogens between hosts are two important challenges for understanding how epizootics wax and wane and how disease influences host population dynamics. For the management of marine shellfish resources, marine diseases pose additional challenges in early intervention after the appearance of disease, management of the diseased population to limit a decline in host abundance, and application of measures to restrain that decline once it occurs. Mathematical models provide one approach for quantifying these effects and addressing the competing goals of managing the diseased population versus managing the disease. The majority of models for molluscan diseases fall into three categories distinguished by these competing goals. (1) Models that consider disease effects on the host population tend to focus on pathogen proliferation within the host. Many of the well-known molluscan diseases are pandemic, in that they routinely reach high prevalence rapidly over large geographic expanses, are characterized by transmission that does not depend upon a local source, and exert a significant influence on host population dynamics. Models focused on disease proliferation examine the influence of environmental change on host population metrics and provide a basis to better manage diseased stocks. Such models are readily adapted to questions of fishery management and habitat restoration. (2) Transmission models are designed to understand the mechanisms triggering epizootics, identify factors impeding epizootic development, and evaluate controls on the rate of disease spread over the host's range. Transmission models have been used extensively to study terrestrial diseases, yet little attention has been given to their potential for understanding the epidemiology of marine molluscan diseases. For management of diseases of wild stocks, transmission models open up a range of options, including the application of area

Epizootic ulcerative syndrome caused by Aphanomyces invadans in captive bullseye snakehead Channa marulius collected from south Florida, USA

Science.gov (United States)

Saylor, Ryan K.; Miller, Debra L.; Vandersea, Mark W.; Bevelhimer, Mark S.; Schofield, Pamela J.; Bennett, Wayne A.

2010-01-01

Epizootic ulcerative syndrome (EUS) caused by the oomycete Aphanomyces invadans is an invasive, opportunistic disease of both freshwater and estuarine fishes. Originally documented as the cause of mycotic granulomatosis of ornamental fishes in Japan and as the cause of EUS of fishes in southeast Asia and Australia, this pathogen is also present in estuaries and freshwater bodies of the Atlantic and gulf coasts of the USA. We describe a mass mortality event of 343 captive juvenile bullseye snakehead Channa marulius collected from freshwater canals in Miami-Dade County, Florida. Clinical signs appeared within the first 2 d of captivity and included petechiae, ulceration, erratic swimming, and inappetence. Histological examination revealed hyphae invading from the skin lesions deep into the musculature and internal organs. Species identification was confirmed using a species-specific PCR assay. Despite therapeutic attempts, 100% mortality occurred. This represents the first documented case of EUS in bullseye snakehead fish collected from waters in the USA. Future investigation of the distribution and prevalence of A. invadans within the bullseye snakehead range in south Florida may give insight into this pathogen-host system.

Epizootic canine distemper virus infection among wild mammals.

Science.gov (United States)

Kameo, Yuki; Nagao, Yumiko; Nishio, Yohei; Shimoda, Hiroshi; Nakano, Hitoshi; Suzuki, Kazuo; Une, Yumi; Sato, Hiroshi; Shimojima, Masayuki; Maeda, Ken

2012-01-27

In the spring of 2007, seven raccoon dogs and a weasel were captured near the city of Tanabe in Wakayama prefecture, Japan. The causative agent of the animals' death 1-2 days after capture was identified as canine distemper virus (CDV) by virus isolation, immunostaining with an anti-CDV polyclonal antibody, and a commercially available CDV antigen-detection kit. Sequence analysis of hemagglutinin genes indicated the isolated viruses belong to genotype Asia-1 and possess the substitution from tyrosine (Y) to histidine (H) at position 549 that is associated with the spread of CDV to non-canine hosts. A serosurvey for CDV was then conducted among wild animals in the region. The animals assayed consisted of 104 raccoons, 41 wild boars, 19 raccoon dogs, five Sika deer, two badgers, one weasel, one marten, one Siberian weasel and one fox. Virus-neutralization (VN) tests showed that, except for fox and weasel, all of the species assayed had VN antibodies to CDV. Interestingly, 11 of the 41 wild boars (27%) and two of the five Sika deer assayed possessed VN antibodies to CDV. These findings indicate that CDV infection was widespread among wild mammals during this epizootic. Copyright © 2011 Elsevier B.V. All rights reserved.

Why did bluetongue spread the way it did? Environmental factors influencing the velocity of bluetongue virus serotype 8 epizootic wave in France.

Science.gov (United States)

Pioz, Maryline; Guis, Hélène; Crespin, Laurent; Gay, Emilie; Calavas, Didier; Durand, Benoît; Abrial, David; Ducrot, Christian

2012-01-01

Understanding where and how fast an infectious disease will spread during an epidemic is critical for its control. However, the task is a challenging one as numerous factors may interact and drive the spread of a disease, specifically when vector-borne diseases are involved. We advocate the use of simultaneous autoregressive models to identify environmental features that significantly impact the velocity of disease spread. We illustrate this approach by exploring several environmental factors influencing the velocity of bluetongue (BT) spread in France during the 2007-2008 epizootic wave to determine which ones were the most important drivers. We used velocities of BT spread estimated in 4,495 municipalities and tested sixteen covariates defining five thematic groups of related variables: elevation, meteorological-related variables, landscape-related variables, host availability, and vaccination. We found that ecological factors associated with vector abundance and activity (elevation and meteorological-related variables), as well as with host availability, were important drivers of the spread of the disease. Specifically, the disease spread more slowly in areas with high elevation and when heavy rainfall associated with extreme temperature events occurred one or two months prior to the first clinical case. Moreover, the density of dairy cattle was correlated negatively with the velocity of BT spread. These findings add substantially to our understanding of BT spread in a temperate climate. Finally, the approach presented in this paper can be used with other infectious diseases, and provides a powerful tool to identify environmental features driving the velocity of disease spread.

Batrachochytrium dendrobatidis infection patterns among Panamanian amphibian species, habitats and elevations during epizootic and enzootic stages.

Science.gov (United States)

Brem, Forrest M R; Lips, Karen R

2008-09-24

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has caused declines of many amphibian populations, yet the full course of the epizootic has rarely been observed in wild populations. We determined effects of elevation, habitat, and aquatic index (AI) on prevalence of infection among Panamanian amphibians sampled along 2 elevational transects. Amphibian populations on the Santa Fé transect (SFT) had declined in 2002, while those on the El Copé transect (ECT) were healthy until September 2004. In 2004 we sampled Bd along both transects, surveying the SFT 2 yr after decline, and surveying the ECT 4 mo prior to the arrival of Bd, during the epizootic, and 2 mo later. Overall prevalence of Bd along the ECT increased from 0.0 (95% CI 0.00-0.0003) to 0.51 (95% CI 0.48-0.55) over a 3 mo period, accompanied by significant decreases in amphibian abundance and species richness in all habitats. Prevalence of infection on the ECT was highest along riparian transects and at higher elevations, but not among levels of AI. Prevalence of infection on the SFT was highest in pool transects, and at higher elevations, but not among levels of AI. Riparian amphibian abundance and species richness also declined at SFT following detection of Bd in 2002. Variation among species, microenvironmental conditions, and the length of coexistence with Bd may contribute to observed differences in prevalence of Bd and in population response.

Pathogenesis of new strains of Newcastle disease virus from Israel and Pakistan

Science.gov (United States)

In the past few years, Newcastle disease virus (NDV) strains with epizootic characteristics belonging to subgenotypes VIIi and XIIIb emerged in the Middle East and Asia. In this study, 2 NDV strains—1 representative of subgenotype VIIi isolated in Israel (Kvuzat/13) and 1 representative of subgenoty...

Yellow fever epizootics in non-human primates, São Paulo state, Brazil, 2008-2009 Epizootias de febre amarela em primatas não humanos no estado de São Paulo, Brasil, 2008-2009

Directory of Open Access Journals (Sweden)

Eduardo Stramandinoli Moreno

2013-02-01

Full Text Available Since 2000, the expansion of Sylvatic Yellow Fever (YF has been observed in the southeast of Brazil, being detected in areas considered silent for decades. Epizootics in non-human primates (NHPs are considered sentinel events for the detection of human cases. It is important to report epizootic events that could have impact on the conservation status of susceptible species. We describe the epizootics in NHPs, notified in state of São Paulo, Brazil, between September 2008 to August 2009. Ninety-one epizootic events, involving 147 animals, were reported in 36 counties. Samples were obtained from 65 animals (44.2%. Most of the epizootics (46.6% were reported between March and April, the same period during which human cases of YF occurred in the state. Biological samples were collected from animals found dead and were sent to Instituto Adolfo Lutz, in São Paulo. Two samples, collected in two counties without an indication for YF vaccination, were positive for the virus. Another 48 animals were associated with YF by clinical-epidemiological linkage with laboratory confirmed cases. Because the disease in human and NHPs occurred in the same period, the detection of the virus in NHPs did not work as sentinel, but aided in the delineation of new areas of risk.Desde 2000, vem sendo observada a expansão da febre amarela (FA no Sudeste do Brasil, sendo detectados casos em áreas consideradas silenciosas por décadas. Epizootias em primatas não humanos (NHPs são considerados eventos sentinela para a detecção de casos humanos. É importante relatar eventos epizoóticos que podem ter impacto sobre o estado de conservação de espécies sensíveis. Descrevemos as epizootias, notificadas em NHPs no estado de São Paulo, Brasil, entre setembro de 2008 a agosto de 2009. Noventa e um eventos epizoóticos, envolvendo 147 animais, foram notificados em 36 municípios. As amostras foram obtidas a partir de 65 animais (44,2%. A maioria das epizootias (46,6% foram

Innate immune response against an oomycete pathogen Aphanomyces invadans in common carp (Cyprinus carpio), a fish resistant to epizootic ulcerative syndrome.

Science.gov (United States)

Yadav, Manoj K; Pradhan, Pravata K; Sood, Neeraj; Chaudhary, Dharmendra K; Verma, Dev K; Chauhan, U K; Punia, Peyush; Jena, Joy K

2016-03-01

Infection with Aphanomyces invadans, also known as epizootic ulcerative syndrome, is a destructive disease of freshwater and brackishwater fishes. Although more than 130 species of fish have been confirmed to be susceptible to this disease, some of the commercially important fish species like common carp, milk fish and tilapia are reported to be resistant. Species that are naturally resistant to a particular disease, provide a potential model to study the mechanisms of resistance against that disease. In the present study, following experimental infection with A. invadans in common carp Cyprinus carpio, sequential changes in various innate immune parameters and histopathological alterations were monitored. Some of the studied innate immunity parameters viz. respiratory burst, alternative complement and total antiproteases activities of the infected common carp were higher compared to control fish, particularly at early stages of infection. On the other hand, some parameters such as myeloperoxidase, lysozyme and alpha-2 macroglobulin activities were not altered. Histopathological examination of the muscle at the site of injection revealed well developed granulomas at 12 days post infection, with subsequent regeneration of muscle fibers. From the results, it could be inferred that innate defense mechanisms of common carp are able to neutralize the virulence factors secreted by A. invadans, thereby, preventing its invasive spread and containing the infection. The results obtained here will help to better understand the mechanisms underlying resistance against A. invadans infection. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

An Ichthyophonus hoferi epizootic in herring in the North Sea, the Skagerrak, the Kattegat and the Baltic Sea

OpenAIRE

Mellergaard, Stig; Spanggaard, Bettina

1997-01-01

An epizootic caused by the internal parasite Ichthyophonus hoferi in herring Clupea harengus was recorded from 1991 to 1993 in the waters around Denmark. A surveillance programme from research vessels and commercial fishing boats was conducted in the North Sea, Skagerrak, Kattegat and Baltic Sea. A total of 15769 hearts of adult herring were examined macroscopically for evidence of infection. The prevalence of the infection in this period decreased from 10.6 to 2.0% in the North Sea, from 8.0...

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

THE CONDITION OF CORAL REEFS IN SOUTH FLORIDA (2000) USING CORAL DISEASE AND BLEACHING AS INDICATORS

Science.gov (United States)

The destruction for coral reef habitats is occurring at unprecedented levels. Coral disease epizootics in the Southwestern Atlantic have lead to coral replacement by turf algae, prompting a call to classify some coral species as endangered. In addition, a massive bleaching event ...

An outbreak of Newcastle disease in free-living pheasants (Phasianus colchicus)

DEFF Research Database (Denmark)

Jørgensen, Poul Henrik; Handberg, Kurt; Ahrens, Peter

1999-01-01

The epidemiology of an outbreak of Newcastle disease in a population of approximately 12 000 free-living pheasants (Phasianus colchicus) on the island of Faeno in Denmark in 1996 is described. The mortality epizootic demonstrated over an observation period of 3 weeks. A total of 70 avian paramyxo...... to the pheasants by feral birds....

Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density.

Science.gov (United States)

Sugiura, Natsuko; Doi, Kandai; Kato, Takuya; Morita, Tatsushi; Hayama, Shin-Ichi

2018-03-30

To examine outbreaks of mange in raccoon dogs (Nyctereutes procyonoides) with respect to population density, we analyzed camera trap videos, and isolated mites from raccoon dog carcasses. In a camera trapping survey, we categorized the skin condition of raccoon dogs, and used a number of independent videos to calculate the relative abundance index (RAI). The RAI of raccoon dogs with alopecia increased following an increase in the RAI of those without alopecia. Among 27 raccoon dog carcasses, 12 showed mange-compatible skin lesions. Sarcoptes scabiei was isolated from 11 of these raccoon dogs, indicating that sarcoptic mange was endemic in our study area. Therefore, a high relative population density may be a factor underlying epizootics of sarcoptic mange in raccoon dogs.

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

Neglect and not forgetting produces shameful diseases such as yellow fever

Directory of Open Access Journals (Sweden)

Salim Mattar V

2017-05-01

Full Text Available Yellow fever (YF is a disease caused by a flavivirus that bears its name, is a disease with haemorrhagic manifestations and high lethality that compromises the central nervous system. YF has two cycles; one in the jungle and another urban, epizootics precede outbreaks before migrating to urban areas. The vectors are the mosquitoes Aedes aegypti, Aedes albopictus, Haemogogus janthinomys and Sabethes sp, which have a wide geographical distribution in Colombia and South America.

Development of field-deployable instrumentation based on “antigen–antibody” reactions for detection of hemorrhagic disease in ruminants

Science.gov (United States)

Development of field-deployable methodology utilizing antigen–antibody reactions and the surface Plasmon resonance (SPR) effect to provide a rapid diagnostic test for recognition of the blue tongue virus (BTV) and epizootic hemorrhage disease virus (EHDV) in wild and domestic ruminants is reported. ...

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.

Phylogenetic analysis of feline coronavirus strains in an epizootic outbreak of feline infectious peritonitis.

Science.gov (United States)

Barker, E N; Tasker, S; Gruffydd-Jones, T J; Tuplin, C K; Burton, K; Porter, E; Day, M J; Harley, R; Fews, D; Helps, C R; Siddell, S G

2013-01-01

Feline coronavirus (FCoV) infection is common. In a small percentage of cats, FCoV infection is associated with the fatal disease feline infectious peritonitis (FIP). Genetically distinct virulent and avirulent strains of FCoV might coexist within a cat population. To determine whether the strains of FCoV in FIP-affected cats are closely related or genetically distinct from the fecally derived strains of FCoV in contemporary-asymptomatic cats during an epizootic outbreak of FIP. Four cats euthanized because of FIP and 16 asymptomatic cats. This prospective outbreak investigation was initiated during an outbreak of FIP in cats within or rehomed from a rescue/rehoming center. Postmortem samples were collected from cats with FIP and contemporaneous fecal samples from asymptomatic cats. RNA was purified from tissue and fecal samples, FCoV gene fragments were reverse transcribed, PCR-amplified using novel primers, and sequenced. Sequences were aligned with ClustalW and compared with published FCoV sequences. FCoV RNA was detected in all 4 FIP cat postmortem samples and in 9 of the 16 fecal samples from contemporary-asymptomatic cats. Novel primers successfully amplified fragments from 4 regions of the genome for all FCoV-positive samples. Phylogenetic analysis showed that the FIP-associated strains of FCoV from the outbreak were very closely related to the fecally derived strains of FCoV from contemporary-asymptomatic cats. Sequence analysis provided no evidence that genetically distinct virulent and avirulent strains of FCoV were present during this FIP outbreak. Copyright © 2013 by the American College of Veterinary Internal Medicine.

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

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.

A behaviorally-explicit approach for delivering vaccine baits to mesopredators to control epizootics in fragmented landscapes.

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James C Beasley

Full Text Available Despite the widespread use of aerial baiting to manage epizootics among free-ranging populations, particularly in rabies management, bait acceptance and seroconversion rates often are lower than required to eliminate spread of disease. Our objectives in this study, therefore, were to evaluate the performance of stratified bait distribution models derived from resource selection functions (RSF on uptake of placebo rabies baits by raccoons (Procyon lotor and Virginia opossums (Didelphis virginiana, as well as the probability of bait uptake as a function of proximity to bait distribution areas in fragmented agricultural ecosystems. Among 478 raccoons and 108 opossums evaluated for presence of Rhodamine B (RB across 8 sites, only 26% of raccoons and 20% of opossums exhibited marking consistent with bait consumption 14-24 days post-baiting. The effective area treated, based on 90% kernel density estimators of marked individuals, ranged from 99-240 ha larger than bait distribution zones, with RB marked individuals captured up to 753 m beyond the bait zone. Despite incorporation of RSF data into bait distribution models, no differences in uptake rates were observed between treatment and control sites. These data likely reflect the underlying constraints imposed by the loss and fragmentation of habitat on animal movement in heterogeneous landscapes, forcing individuals to optimize movements at coarse (i.e., patch-level rather than fine spatial scales in highly fragmented environments. Our data also confirm that the probability of bait acceptance decreases with increasing distance from bait zone interiors, even within the zone itself. Thus, although bait acceptance was confirmed beyond bait zone boundaries, the proportion of vaccinated individuals may comprise a small minority of the population at increasing distances from baiting interiors. These data suggest focal baiting creates a buffered area of treated individuals around bait zones or bait stations

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.

Viral diseases of northern ungulates

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K. Frölich

2000-03-01

Full Text Available This paper describes viral diseases reported in northern ungulates and those that are a potential threat to these species. The following diseases are discussed: bovine viral diarrhoea/mucosal disease (BVD/MD, alphaherpesvirus infections, malignant catarrhal fever (MCF, poxvirus infections, parainfluenza type 3 virus infection, Alvsborg disease, foot-and-mouth disease, epizootic haemorrhage disease of deer and bluetongue disease, rabies, respiratory syncytial virus infection, adenovirus infection, hog-cholera, Aujeszky's disease and equine herpesvirus infections. There are no significant differences in antibody prevalence to BVDV among deer in habitats with high, intermediate and low density of cattle. In addition, sequence analysis from the BVDV isolated from roe deer (Capreolus capreolus showed that this strain was unique within BVDV group I. Distinct BVDV strains might circulate in free-ranging roe deer populations in Germany and virus transmission may be independent of domestic livestock. Similar results have been obtained in a serological survey of alpha-herpesviruses in deer in Germany. Malignant catarrhal fever was studied in fallow deer (Cervus dama in Germany: the seroprevalence and positive PCR results detected in sheep originating from the same area as the antibody-positive deer might indicate that sheep are the main reservoir animals. Contagious ecthyma (CE is a common disease in domestic sheep and goats caused by the orf virus. CE has been diagnosed in Rocky Mountain bighorn sheep (Ovis canadensis, mountain goats (Oreamnos americanus, Dall sheep (Ovis dalli, chamois (Rupkapra rupi-capra, muskox {Ovibos moschatus and reindeer (Rangifer tarandus. Most parainfluenza type 3 virus infections are mild or clinically undetectable. Serological surveys in wildlife have been successfully conducted in many species. In 1985, a new disease was identified in Swedish moose (Alces alces, designated as Alvsborg disease. This wasting syndrome probably

Etiology of sockeye salmon 'virus' disease

Science.gov (United States)

Guenther, Raymond W.; Watson, S.W.; Rucker, R.R.; Ross, A.J.

1959-01-01

Violent epizootics among hatchery reared sockeye salmon fingerlings (Oncorhynchus nerka) caused by a filterable agent have occurred. In 1954, one source of this infectious, filterable agent was found to be adult sockeye viscera used in the diet for the fingerlings. The results of observations on an epizootic in 1958 indicate that the infection may be transmitted to fingerlings from a water supply to which adult sockeye salmon have access.

Modelling local dispersal of Bluetongue virus serotype 8 using random walk.

NARCIS (Netherlands)

Gerbier, G.; Baldet, T.; Tran, A.; Hendrickx, G.; Guis, H.; Mintiens, K.; Elbers, A.R.W.; Staubach, C.

2008-01-01

The knowledge of the place where a disease is first introduced and from where it later spreads is a key element for the understanding of an epizootic. For a contagious disease, the main method is back tracing. For a vector-borne disease such as the Bluetongue virus serotype 8 epizootic that occurred

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.

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

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.

Biotin-avidin sandwich elisa with specific human isotypes IgG1 and IgG4 for Culicidae mosquito blood meal identification from an epizootic yellow fever area in Brazil

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AM Marassá

2009-01-01

Full Text Available With a view toward investigating the feeding behavior of Culicidae mosquitoes from an area of epizootic yellow fever transmission in the municipalities of Garruchos and Santo Antônio das Missões, Rio Grande do Sul State, Brazil, specimens were collected by aspiration from September 2005 to April 2007. The engorged females were submitted to blood meal identification by enzyme-linked immunosorbent assay (ELISA. A total of 142 blood-engorged samples were examined for human or monkey blood through species-specific IgG. Additional tests for specificity utilizing isotypes IgG1 and IgG4 of human monoclonal antibodies showed that only anti-human IgG1 was effective in recognizing blood meals of human origin. The results indicated a significant difference (p = 0.027 in detection patterns in samples of Haemagogus leucocelaenus recorded from human blood meals at Santo Antônio das Missões, which suggests some degree of exposure, since it was an area where epizootic outbreaks have been reported.

Bighorn sheep pneumonia: sorting out the cause of a polymicrobial disease.

Science.gov (United States)

Besser, Thomas E; Frances Cassirer, E; Highland, Margaret A; Wolff, Peregrine; Justice-Allen, Anne; Mansfield, Kristin; Davis, Margaret A; Foreyt, William

2013-02-01

Pneumonia of bighorn sheep (Ovis canadensis) is a dramatic disease of high morbidity and mortality first described more than 80 years ago. The etiology of the disease has been debated since its initial discovery, and at various times lungworms, Mannheimia haemolytica and other Pasteurellaceae, and Mycoplasma ovipneumoniae have been proposed as primary causal agents. A multi-factorial "respiratory disease complex" has also been proposed as confirmation of causation has eluded investigators. In this paper we review the evidence for each of the candidate primary agents with regard to causal criteria including strength of association, temporality, plausibility, experimental evidence, and analogy. While we find some degree of biological plausibility for all agents and strong experimental evidence for M. haemolytica, we demonstrate that of the alternatives considered, M. ovipneumoniae is the best supported by all criteria and is therefore the most parsimonious explanation for the disease. The strong but somewhat controversial experimental evidence implicating disease transmission from domestic sheep is consistent with this finding. Based on epidemiologic and microbiologic data, we propose that healthy bighorn sheep populations are naïve to M. ovipneumoniae, and that its introduction to susceptible bighorn sheep populations results in epizootic polymicrobial bacterial pneumonia often followed by chronic infection in recovered adults. If this hypothesized model is correct, efforts to control this disease by development or application of vectored vaccines to Pasteurellaceae are unlikely to provide significant benefits, whereas efforts to ensure segregation of healthy bighorn sheep populations from M. ovipneumoniae-infected reservoir hosts are crucial to prevention of new disease epizootics. It may also be possible to develop M. ovipneumoniae vaccines or other management strategies that could reduce the impact of this devastating disease in bighorn sheep. Copyright © 2012

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.

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.

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)

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.

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.

Comparison of Active Carbon, Sawdust, Almond Shell and Hazelnut Shell Absorbent in Removal of Nickel from Aqueous Environment

Directory of Open Access Journals (Sweden)

Moslem Mohammadi Galehzan

2013-09-01

Full Text Available The most important environmental pollutants are heavy metals in industrial wastewater effluents. Nickel is one of the toxic heavy metals which its high concentration causes skin allergy, heart disease and various cancers. So removal of this element from industrial effluent is of prime concern and necessary. The main purpose of this study is to compare kinetics and isotherms of nickel uptake by activated carbon (AC, sawdust (SD, hazelnut shell (SH and almond shells (AH. Adsorbents are initially prepared to remove nickel from solutions with concentrations 2.5 to 125 mg/l. pH test results showed that maximum absorption using AC, SH, SD and AH obtained at pH 6, 6, 6 and 7 respectively. Kinetics experiments showed that maximum absorption equilibrium time at concentration of 5 mg/l of AC, SH, SD and AH occur at 60, 75, 120 and 150 minutes respectively. Kinetic models fitting results showed that for sawdust and hazelnut shells, Lagergern model and for activated carbon and peanut shell Ho et al. model are suitable and have the lowest error and highest correlation coefficient at 95 percent confidence level. The results also revealed that rate of Nickel adsorption follows this order: AH

Molecular Characterization of Coccidia Associated with an Epizootic in Green Sea Turtles (Chelonia mydas in South East Queensland, Australia.

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Phoebe A Chapman

Full Text Available In the spring of 2014, mass mortalities among wild green sea turtles occurred off the coast of south-east Queensland, Australia. The suspected causative agent was Caryospora cheloniae, an eimeriid coccidian implicated in previous epizootics. Necropsies were undertaken on a subset of 11 dead turtles, with subsequent histopathology and molecular analyses. All turtles returned positive PCR results for coccidial infection in various tissues; these included the brain, gastrointestinal tract, lung, kidney and thyroid. Granulomatous encephalitis was consistently observed, as well as enteritis and, less frequently, thyroiditis and nephritis. Sequencing and phylogenetic analyses indicated the presence of two distinct coccidian genotypes, presumably separate species-one associated with the brain, gastrointestinal tract and lung, and the second with the thyroid and kidney. Maximum likelihood and Bayesian inference analyses placed the first genotype closest to the lankesterellid genus Schellackia, rather than in the Eimeriidae, while the second was paraphyletic to the eimeriids. Presence of coccidial stages in extra-intestinal tissues of the primary host raises questions about the potential presence of intermediate or paratenic hosts within the life cycles, as well as their current placement relative to the genus Caryospora. This study represents the first genetic characterization of this emerging disease agent in green sea turtles, an endangered species, and has relevance for life-cycle elucidation and future development of diagnostics.

Epizootic pertussis focus of hamadryad baboons

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A. Yu. Medkova

2015-01-01

Full Text Available The absence of an adequate experimental animal model makes difficult study of immunity against whooping cough and its pathogenesis. Experimental whooping cough reported by us earlier in pubescent non-human primates of the Old World was accompanied by specific clinical and laboratory marks in the absence of cough. The possibility of pertussis modelling while experimental whooping cough in impuberal hamadryad baboons was investigated. In the process of selection of monkeys for the further studies for perfecting of experimental model for pertussis research unexpectedly were detected specific pertussis antibodies in impuberal hamadryad baboons.The aim of the study: revealing of source of infection and transmission of pertussis to hamadryad baboons and investigation of response of antibody-positive impuberal hamadryad baboons to secondary contagion by B. pertussis bacteria while experimental infection.Results. 18 veterinary checked, somatically healthy hamadryad baboons of various gender managed in two neighboring cages. Specific pertussis IgM and IgG antibodies were found in blood serum of all the animals and one of the monkey keepers. By real-time PCR in nasopharyngeal swabs of the monkey keeper and three 7- and 9-month-old hamadryad baboons were registered single B. pertussis genom equivalents. Seropositive impuberal hamadryad baboons were experimentally challenged by virulent B. pertussis 475 strain. Quantity of B. pertussis genom equivalents and percentage of IgM and IgG antibodies in impuberal hamadryad baboons after experimental infection were detected. These results were comparable with such received after secondary experimental challenge of monkeys by B. pertussis. Humoral immuneresponse was characterized by booster effect and rapid B. pertussis elimination.Conclusion. The case of transmission of B.pertussis bacteria to hamadryad baboons by natural contagion and epizootic focus of pertussis in apery conditions

Epidemiology of Chronic Wasting Disease: PrPres Detection, Shedding, and Environmental Contamination

Science.gov (United States)

2008-08-01

epizootic hemorrhagic disease (EHD) epidemics in Aug−Sep 2006 and 2007 killed six otherwise apparently healthy white-tailed deer (1 96GG, 3 96GS, and 2...in inoculated white-tailed deer; seasonal EHD epidemics killed six otherwise healthy white-tailed deer during the course of this study, thereby...precautionary measure, all of the elk in this study group were treated with Nuflor (Schering- Plough Animal Health, Union, New Jersey). The sampling

Ancient DNA analysis identifies marine mollusc shells as new metagenomic archives of the past.

Science.gov (United States)

Der Sarkissian, Clio; Pichereau, Vianney; Dupont, Catherine; Ilsøe, Peter C; Perrigault, Mickael; Butler, Paul; Chauvaud, Laurent; Eiríksson, Jón; Scourse, James; Paillard, Christine; Orlando, Ludovic

2017-09-01

Marine mollusc shells enclose a wealth of information on coastal organisms and their environment. Their life history traits as well as (palaeo-) environmental conditions, including temperature, food availability, salinity and pollution, can be traced through the analysis of their shell (micro-) structure and biogeochemical composition. Adding to this list, the DNA entrapped in shell carbonate biominerals potentially offers a novel and complementary proxy both for reconstructing palaeoenvironments and tracking mollusc evolutionary trajectories. Here, we assess this potential by applying DNA extraction, high-throughput shotgun DNA sequencing and metagenomic analyses to marine mollusc shells spanning the last ~7,000 years. We report successful DNA extraction from shells, including a variety of ancient specimens, and find that DNA recovery is highly dependent on their biomineral structure, carbonate layer preservation and disease state. We demonstrate positive taxonomic identification of mollusc species using a combination of mitochondrial DNA genomes, barcodes, genome-scale data and metagenomic approaches. We also find shell biominerals to contain a diversity of microbial DNA from the marine environment. Finally, we reconstruct genomic sequences of organisms closely related to the Vibrio tapetis bacteria from Manila clam shells previously diagnosed with Brown Ring Disease. Our results reveal marine mollusc shells as novel genetic archives of the past, which opens new perspectives in ancient DNA research, with the potential to reconstruct the evolutionary history of molluscs, microbial communities and pathogens in the face of environmental changes. Other future applications include conservation of endangered mollusc species and aquaculture management. © 2017 John Wiley & Sons Ltd.

A SKIN TEST FOR DETECTING GROUP C HEMOLYTIC STREPTOCOCCAL INFECTION CAUSING EPIZOOTIC LYMPHADENITIS IN GUINEA PIGS

Science.gov (United States)

Moen, Johannes K.

1936-01-01

1. A skin test with a crude bacterial extract prepared from group C (Lancefield) hemolytic streptococci was used as a means of detecting possible carriers of the streptococcus causing epizootic lymphadenitis in guinea pigs. A positive test similar to a positive tuberculin reaction was considered presumptive evidence of present or recent infection with this streptococcus. 2. 20 positive reactors were found in 330 supposedly normal guinea pigs. 3. 195 negatively reacting animals were used as a breeding stock which yielded 1,296 progeny over a period of 15 months. None of the breeding stock or their progeny showed evidence of spontaneous lymphadenitis. Skin tests of 100 of the progeny were all negative. 4. The use of this skin test as a means of obtaining guinea pig breeding stock free of the streptococcus causing spontaneous lymphadenitis is suggested. PMID:19870552

Chronic nutrient enrichment increases prevalence and severity of coral disease and bleaching.

Science.gov (United States)

Vega Thurber, Rebecca L; Burkepile, Deron E; Fuchs, Corinne; Shantz, Andrew A; McMinds, Ryan; Zaneveld, Jesse R

2014-02-01

Nutrient loading is one of the strongest drivers of marine habitat degradation. Yet, the link between nutrients and disease epizootics in marine organisms is often tenuous and supported only by correlative data. Here, we present experimental evidence that chronic nutrient exposure leads to increases in both disease prevalence and severity and coral bleaching in scleractinian corals, the major habitat-forming organisms in tropical reefs. Over 3 years, from June 2009 to June 2012, we continuously exposed areas of a coral reef to elevated levels of nitrogen and phosphorus. At the termination of the enrichment, we surveyed over 1200 scleractinian corals for signs of disease or bleaching. Siderastrea siderea corals within enrichment plots had a twofold increase in both the prevalence and severity of disease compared with corals in unenriched control plots. In addition, elevated nutrient loading increased coral bleaching; Agaricia spp. of corals exposed to nutrients suffered a 3.5-fold increase in bleaching frequency relative to control corals, providing empirical support for a hypothesized link between nutrient loading and bleaching-induced coral declines. However, 1 year later, after nutrient enrichment had been terminated for 10 months, there were no differences in coral disease or coral bleaching prevalence between the previously enriched and control treatments. Given that our experimental enrichments were well within the ranges of ambient nutrient concentrations found on many degraded reefs worldwide, these data provide strong empirical support to the idea that coastal nutrient loading is one of the major factors contributing to the increasing levels of both coral disease and coral bleaching. Yet, these data also suggest that simple improvements to water quality may be an effective way to mitigate some coral disease epizootics and the corresponding loss of coral cover in the future. © 2013 John Wiley & Sons Ltd.

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.

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.

Mule deer spatial association patterns and potential implications for transmission of an epizootic disease.

Directory of Open Access Journals (Sweden)

María Fernanda Mejía-Salazar

Full Text Available Animal social behaviour can have important effects on the long-term dynamics of diseases. In particular, preferential spatial relationships between individuals can lead to differences in the rates of disease spread within a population. We examined the concurrent influence of genetic relatedness, sex, age, home range overlap, time of year, and prion disease status on proximal associations of adult Rocky Mountain mule deer (Odocoileus hemionus hemionus in a chronic wasting disease endemic area. We also quantified the temporal stability of these associations across different sex, age, and disease status classes. We used three years of high frequency telemetry data from 74 individuals to record encounters within 25 m of each other, and to calculate seasonal home range overlap measured by volume of intersection (VI. The strength of pairwise spatial association between adult mule deer was independent of genetic relatedness, age and disease status. Seasonal variation in association strength was not consistent across years, perhaps due to annual changes in weather conditions. The influence of home range overlap on association strength varied seasonally, whereby associations were stronger in pre-rut and fawning than in the rest of the seasons. The sexes of individuals also interacted with both VI and season. At increasing levels of VI, associations were stronger between females than between males and between females and males. The strongest associations in pre-rut were between males, while the strongest in rut were between females and males. The temporal stability of associations was markedly dependant on the sex and the diagnosis of the associating pair. Our findings highlight the importance of considering concurrent effects of biological and environmental factors when seeking to understand the role of social preference in behavioural ecology and disease spread. Applying this knowledge in epidemiological modelling will shed light on the dynamics of

Challenge studies of European stocks of redfin perch, Perca fluviatilis L., and rainbow trout, Oncorhynchus mykiss (Walbaum), with epizootic haematopoietic necrosis virus

DEFF Research Database (Denmark)

Ariel, Ellen; Jensen, Ann Britt Bang

2009-01-01

indicate that EHNV does not pose a high risk for wild perch and trout populations in Europe by natural exposure. Mortality appears to be primarily a function of environmental factors, with temperature playing an important role, and not just the presence of the virus in the fish.......A challenge model for comparison of the virulence of epizootic haematopoietic necrosis virus (EHNV) to European stock of redfin perch, Perca fluviatilis L., and rainbow trout, Oncorhynchus mykiss (Walbaum), was tested. The model investigated intraperitoneal (IP), bath and cohabitation routes at 10...

Core-shell designed scaffolds for drug delivery and tissue engineering.

Science.gov (United States)

Perez, Roman A; Kim, Hae-Won

2015-07-01

Scaffolds that secure and deliver therapeutic ingredients like signaling molecules and stem cells hold great promise for drug delivery and tissue engineering. Employing a core-shell design for scaffolds provides a promising solution. Some unique methods, such as co-concentric nozzle extrusion, microfluidics generation, and chemical confinement reactions, have been successful in producing core-shelled nano/microfibers and nano/microspheres. Signaling molecules and drugs, spatially allocated to the core and/or shell part, can be delivered in a controllable and sequential manner for optimal therapeutic effects. Stem cells can be loaded within the core part on-demand, safely protected from the environments, which ultimately affords ex vivo culture and in vivo tissue engineering. The encapsulated cells experience three-dimensional tissue-mimic microenvironments in which therapeutic molecules are secreted to the surrounding tissues through the semi-permeable shell. Tuning the material properties of the core and shell, changing the geometrical parameters, and shaping them into proper forms significantly influence the release behaviors of biomolecules and the fate of the cells. This topical issue highlights the immense usefulness of core-shell designs for the therapeutic actions of scaffolds in the delivery of signaling molecules and stem cells for tissue regeneration and disease treatment. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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

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

DISCONTOOLS: a database to identify research gaps on vaccines, pharmaceuticals and diagnostics for the control of infectious diseases of animals.

Science.gov (United States)

O'Brien, Declan; Scudamore, Jim; Charlier, Johannes; Delavergne, Morgane

2017-01-03

The public and private sector in the EU spend around €800 million per year on animal health and welfare related research. An objective process to identify critical gaps in knowledge and available control tools should aid the prioritisation of research in order to speed up the development of new or improved diagnostics, vaccines and pharmaceuticals and reduce the burden of animal diseases. Here, we describe the construction of a database based on expert consultation for 52 infectious diseases of animals. For each disease, an expert group produced a disease and product analysis document that formed the basis for gap analysis and prioritisation. The prioritisation model was based on a closed scoring system, employing identical weights for six evaluation criteria (disease knowledge; impact on animal health and welfare; impact on public health; impact on wider society; impact on trade; control tools). The diseases were classified into three groups: epizootic diseases, food-producing animal complexes or zoonotic diseases. The highly ranked diseases in the prioritisation model comprised mostly zoonotic and epizootic diseases with important gaps identified in vaccine development and pharmaceuticals, respectively. The most important outcome is the identification of key research needs by disease. The rankings and research needs by disease are provided on a public website ( www.discontools.eu ) which is currently being updated based on new expert consultations. As such, it can become a reference point for funders of research including the European Commission, member states, foundations, trusts along with private industry to prioritise research. This will deliver benefits in terms of animal health and welfare but also public health, societal benefits and a safe and secure food supply.

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.

Ancient DNA analysis identifies marine mollusc shells as new metagenomic archives of the past

DEFF Research Database (Denmark)

Der Sarkissian, Clio; Pichereau, Vianney; Dupont, Catherine

2017-01-01

Marine mollusc shells enclose a wealth of information on coastal organisms and their environment. Their life history traits as well as (palaeo-) environmental conditions, including temperature, food availability, salinity and pollution, can be traced through the analysis of their shell (micro...... extraction, high-throughput shotgun DNA sequencing and metagenomic analyses to marine mollusc shells spanning the last ~7,000 years. We report successful DNA extraction from shells, including a variety of ancient specimens, and find that DNA recovery is highly dependent on their biomineral structure......, carbonate layer preservation and disease state. We demonstrate positive taxonomic identification of mollusc species using a combination of mitochondrial DNA genomes, barcodes, genome-scale data and metagenomic approaches. We also find shell biominerals to contain a diversity of microbial DNA from the marine...

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.

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.

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

Epizootic and zoonotic helminths of the bobcat (Lynx rufus in Illinois and a comparison of its helminth component communities across the American Midwest

Directory of Open Access Journals (Sweden)

Hiestand Shelby J.

2014-01-01

Full Text Available A total of 6257 helminths of 19 taxa were recovered from the digestive tract and lungs of 67 bobcats in Illinois. Infections caused by Alaria mustelae, Diphyllobothrium latum, and Macracanthorhynchus ingens are reported for the first time in bobcats. From all the taxa recovered, only three species occurred in high prevalence and caused intense infections: Taenia rileyi, Alaria marcianae, and Toxocara cati, with prevalence and mean intensity of 70% and 6; 42% and 193, and 25% and 14 individuals, respectively. Prevalence lower than 15% of 14 helminth species suggests bobcats are not continuously exposed to infective stages of a single parasite, and may be exposed to a large variety of generalists during their lifespan. No significant difference in parasite species according to host sex or age was detected, except for Diphyllobothrium spp., which were found more frequently in females and in trapped bobcats, and the hookworm, Ancylostoma caninum, which infected juveniles more frequently. Average species richness per infracommunity was 2.4 (±1.2, and the parasite component community showed low qualitative similarity with neighbor communities. The taxa A. caninum, Alaria spp., Diphyllobothrium spp., Paragonimus kellicotti, and T. cati are etiological agents of epizootic and zoonotic diseases.

AN EPIZOOTIC OF EMERGING NOVEL AVIAN POX IN CARRION CROWS (CORVUS CORONE) AND LARGE-BILLED CROWS (CORVUS MACRORHYNCHOS) IN JAPAN.

Science.gov (United States)

Fukui, Daisuke; Nakamura, Makiko; Yamaguchi, Tsuyoshi; Takenaka, Makiko; Murakami, Mami; Yanai, Tokuma; Fukushi, Hideto; Yanagida, Kazumi; Bando, Gen; Matsuno, Keita; Nagano, Masashi; Tsubota, Toshio

2016-04-28

In 2006-10, an epizootic of emerging avian pox occurred in Carrion Crows ( Corvus corone ) and Large-billed Crows ( Corvus macrorhynchos ), leading to mortality of juvenile crows in Hokkaido, the northernmost island of Japan. We diagnosed 27 crows with proliferative skin lesions (19 carcasses and eight biopsied cases [one in zoo captivity]) as avian pox clinically, histopathologically by detection of Avipoxvirus-specific 4b core protein (P4b) gene, and epidemiologically. The fatal cases demonstrated intensively severe infection and aggressive lesions with secondary bacterial infection. Since the first identification of avian pox in Sapporo, Japan, in 2006, the frequency of mortality events has increased, peaking in 2007-08. Mortalities have subsequently occurred in other areas, suggesting disease expansion. In Sapporo, prevalence of avian pox evaluated by field censuses during 2007-12 was 17.6% (6.6-27.2%), peaked during 2007-08 and 2008-09, and then decreased. All diseased crows were juveniles, except for one adult. The number of crows assembling in the winter roosts had been stable for >10 yr; however, it declined in 2007-08, decreased by about 50% in 2008-09, and recovered to the previous level in 2009-10, correlated with the avian pox outbreak. Thus, avian pox probably contributed to the unusual crow population decline. All P4b sequences detected in six specimens in Sapporo were identical and different from any previously reported sequences. The sequence detected in the zoo-kept crow was distinct from any reported clades, and interspecies transmission was suspected. This report demonstrates an emerging novel avian pox in the Japanese avifauna and in global populations of Carrion Crows and Large-billed Crows. Longitudinal monitoring is needed to evaluate its impact on the crow population.

Epizootic emergence of Usutu virus in wild and captive birds in Germany.

Directory of Open Access Journals (Sweden)

Norbert Becker

Full Text Available This study aimed to identify the causative agent of mass mortality in wild and captive birds in southwest Germany and to gather insights into the phylogenetic relationship and spatial distribution of the pathogen. Since June 2011, 223 dead birds were collected and tested for the presence of viral pathogens. Usutu virus (USUV RNA was detected by real-time RT-PCR in 86 birds representing 6 species. The virus was isolated in cell culture from the heart of 18 Blackbirds (Turdus merula. USUV-specific antigen was demonstrated by immunohistochemistry in brain, heart, liver, and lung of infected Blackbirds. The complete polyprotein coding sequence was obtained by deep sequencing of liver and spleen samples of a dead Blackbird from Mannheim (BH65/11-02-03. Phylogenetic analysis of the German USUV strain BH65/11-02-03 revealed a close relationship with strain Vienna that caused mass mortality among birds in Austria in 2001. Wild birds from lowland river valleys in southwest Germany were mainly affected by USUV, but also birds kept in aviaries. Our data suggest that after the initial detection of USUV in German mosquitoes in 2010, the virus spread in 2011 and caused epizootics among wild and captive birds in southwest Germany. The data also indicate an increased risk of USUV infections in humans in Germany.

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

Institute of Scientific and Technical Information of China (English)

无

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.

Effectiveness of Shelled Almonds in Decreasing Blood Lipid and Lipoprotein Levels of Hyperlipidemic Patients

Directory of Open Access Journals (Sweden)

H Mozaffari

2008-10-01

Full Text Available Introduction: Hyperlipidemia is a risk factor for atherosclerosis and cardiovascular diseases. Nuts such as almonds are high in unsaturated lipids and antioxidants. Some studies indicate that nuts have beneficial effects on cardiovascular system. Therefore, the aim of this study was evaluation of the effectiveness of shelled almonds on reduction of blood lipid and lipoprotein levels in hyperlipidemic patients. Methods: This study was a clinical trial (before and after and was done on 30 men volunteering for the study. They consumed 60 grams shelled almonds per day for four weeks. Their blood lipid, lipoprotein, apolipoprotein and lipoprotein (a levels were measured after and before almond consumption. Results: Shelled almond consumption caused significant decrease in serum cholesterol 36.1 mg/dl, triglyceride 45.94 mg/dl, LDL-cholesterol 28.68 mg/dl and increase in HDL-cholesterol 10.64 mg/dl(p<0.001. Shelled almond consumption decreased lipoprotein (a (2.11 mg/dl, apolipoprotein B100 (8.93 mg/dl and increased apolipoprotein A (1 1.74 mg/dl levels, but this effect was insignificant statistically. Conclusion: Continuous consumption of shelled almonds has beneficial effect on blood lipids and may play a preventive role in Atherosclerosis and coronary heart diseases. We therefore suggest that a daily intake of 60 grams of almonds can be used for treatment of hyprelipidemic patients.

Venezuelan equine encephalitis emergence: Enhanced vector infection from a single amino acid substitution in the envelope glycoprotein

Science.gov (United States)

Brault, Aaron C.; Powers, Ann M.; Ortiz, Diana; Estrada-Franco, Jose G.; Navarro-Lopez, Roberto; Weaver, Scott C.

2004-01-01

In 1993 and 1996, subtype IE Venezuelan equine encephalitis (VEE) virus caused epizootics in the Mexican states of Chiapas and Oaxaca. Previously, only subtype IAB and IC VEE virus strains had been associated with major outbreaks of equine and human disease. The IAB and IC epizootics are believed to emerge via adaptation of enzootic (sylvatic, equine-avirulent) strains for high titer equine viremia that results in efficient infection of mosquito vectors. However, experimental equine infections with subtype IE equine isolates from the Mexican outbreaks demonstrated neuro-virulence but little viremia, inconsistent with typical VEE emergence mechanisms. Therefore, we hypothesized that changes in the mosquito vector host range might have contributed to the Mexican emergence. To test this hypothesis, we evaluated the susceptibility of the most abundant mosquito in the deforested Pacific coastal locations of the VEE outbreaks and a proven epizootic vector, Ochlerotatus taeniorhynchus. The Mexican epizootic equine isolates exhibited significantly greater infectivity compared with closely related enzootic strains, supporting the hypothesis that adaptation to an efficient epizootic vector contributed to disease emergence. Reverse genetic studies implicated a Ser → Asn substitution in the E2 envelope glycoprotein as the major determinant of the increased vector infectivity phenotype. Our findings underscore the capacity of RNA viruses to alter their vector host range through minor genetic changes, resulting in the potential for disease emergence. PMID:15277679

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.

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.

Hepatoprotective effects of pecan nut shells on ethanol-induced liver damage.

Science.gov (United States)

Müller, Liz Girardi; Pase, Camila Simonetti; Reckziegel, Patrícia; Barcelos, Raquel C S; Boufleur, Nardeli; Prado, Ana Cristina P; Fett, Roseane; Block, Jane Mara; Pavanato, Maria Amália; Bauermann, Liliane F; da Rocha, João Batista Teixeira; Burger, Marilise Escobar

2013-01-01

The hepatoprotective activity of the aqueous extract of the shells of pecan nut was investigated against ethanol-induced liver damage. This by-product of the food industry is popularly used to treat toxicological diseases. We evaluated the phytochemical properties of pecan shell aqueous extract (AE) and its in vitro and ex vivo antioxidant activity. The AE was found to have a high content of total polyphenols (192.4±1.9 mg GAE/g), condensed tannins (58.4±2.2 mg CE/g), and antioxidant capacity, and it inhibited Fe(2+)-induced lipid peroxidation (LP) in vitro. Rats chronically treated with ethanol (Et) had increased plasmatic transaminases (ALT, AST) and gamma glutamyl transpeptidase (GGT) levels (96%, 59.13% and 465.9%, respectively), which were effectively prevented (87; 41 and 383%) by the extract (1:40, w/v). In liver, ethanol consumption increased the LP (121%) and decreased such antioxidant defenses as glutathione (GSH) (33%) and superoxide dismutase (SOD) (47%) levels, causing genotoxicity in erythrocytes. Treatment with pecan shell AE prevented the development of LP (43%), GSH and SOD depletion (33% and 109%, respectively) and ethanol-induced erythrocyte genotoxicity. Catalase activity in the liver was unchanged by ethanol but was increased by the extract (47% and 73% in AE and AE+Et, respectively). Therefore, pecan shells may be an economic agent to treat liver diseases related to ethanol consumption. Copyright © 2011 Elsevier GmbH. All rights reserved.

Myxomatosis on the Western Plains of Victoria.

Science.gov (United States)

Tighe, F G; Edmonds, J W; Nolan, I F; Shepherd, R C; Gocs, A

1977-10-01

Myxomatosis on the Western Plains is an enzootic disease in contrast with the epizootic pattern which is general in eastern Australia. The most unusual aspects are the presence of significant numbers of diseased rabbits throughout the winter and the continuously low percentage of rabbits with antibodies to myxoma virus. Climatic and topographic conditions are unsuited to the production of the high densities of mosquitoes necessary for widespread epizootics. Under these conditions the effects of less efficient methods of myxomatosis transmission are apparent. The unusual epidemiology of myxomatosis has resulted in selection for virulence of the virus similar to that which has occurred under summer epizootic conditions. All field strains are now in the mid range of virulence.

Temporal variation in individual factors associated with hantavirus infection in bank voles during an epizootic: implications for Puumala virus transmission dynamics.

Science.gov (United States)

Tersago, Katrien; Verhagen, Ron; Leirs, Herwig

2011-06-01

Puumala virus (PUUV), the causal agent of nephropathia epidemica in humans, is one of the many hantaviruses included in the list of emerging pathogens. Hantavirus infection is not distributed evenly among PUUV reservoir hosts (i.e., bank voles [Myodes glareolus]). Besides environmental factors and local population features, individual characteristics play an important role in vole PUUV infection risk. Identifying the relative importance of these individual characteristics can provide crucial information on PUUV transmission processes. In the present study, bank voles were monitored during the nephropathia epidemica outbreak of 2005 in Belgium. Vole sera were tested for presence of immunoglobulin G against PUUV, and a logistic mixed model was built to investigate the temporal variation in individual characteristics and their relative importance to PUUV infection risk in bank voles. Relative risk calculations for individual vole characteristics related to PUUV infection in the reservoir host show that reproductive activity dominates infection risk. The gender effect is only found in reproductively active voles, where reproductively active males have the highest infection risk. Results also revealed a clear seasonal variation in the importance of reproductive activity linked to PUUV infection. In contrast to the main effect found in other trapping sessions, no difference in infection risk ratio was found between reproductively active and nonactive voles in the spring period. Combined with increased infection risk for the reproductively nonactive group at that time, these results indicate a shift in the transmission process due to changes in bank vole behavior, physiology, or climate conditions. Hence, our results suggest that mathematical models should take into account seasonal shifts in transmission mechanisms. When these results are combined with the seasonal changes in population structure during the epizootic period, we identify vole reproductive activity and

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.)

Characterization of chitinolytic bacteria and histological aspects of Shell Disease Syndrome in European spiny lobsters (Palinurus elephas) (Fabricius 1787).

Science.gov (United States)

Mancuso, M; Costanzo, M T; Maricchiolo, G; Gristina, M; Zaccone, R; Cuccu, D; Genovese, L

2010-07-01

The present research reports the first description of Shell Disease Syndrome in European spiny lobsters Palinurus elephas (Fabricius 1787), which occurred in an experimental aquaculture facility in Sicily (Italy). Both bacterial characterization and histopathological examination of the exoskeleton at site of lesions was carried out. Infected specimens showed tail fan erosions, and in one case uropod ulceration and complete loss of periods. Identified species included: Listonella anguillarum 50.5%, Vibrio parahaemolyticus 27.5% and Vibrio alginolyticus 22%. Microscopic evaluation of lesions indicate the presence of inflammatory responses, which include melanization and pseudomembrane formation, similar to those described for other crustaceans affected by SDS. (c) 2010 Elsevier Inc. All rights reserved.

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.

Disease prevalence in flounder (Platichthys flesus) from the Dutch Wadden Sea as indicator of environmental quality: A summary of 1988-2005 surveys

Science.gov (United States)

Vethaak, A. D.

2013-09-01

In 1988, epizootics of ulcer disease in the flatfish flounder in the Dutch Wadden Sea were reported near freshwater drainage sluices of IJsselmeer Lake, locally affecting up to 38.9% of fish. Other diseases such as fin rot and lymphocystis were less frequent, but followed a similar pattern. Results of follow-up surveys in the Wadden Sea in 1994-2005 confirm previous findings and also show significantly elevated ulcer prevalences at other smaller drainage works. The most likely stress factors that contributed to the development of the epizootics at these sites include osmotic stress, adverse water quality conditions including chemical contaminants, nutritional deficiencies, and obstruction to fish migration. It was shown that discharges of IJsselmeer Lake freshwater in 1988-96 had a wide effect on the prevalence and distribution of ulcers and lymphocystis in the western Wadden Sea. A general reduction in disease prevalence in flounder in the entire Dutch Wadden Sea was observed during 1988-2005, which was most likely due to a general improvement in water quality and locally improved habitat conditions for flounder near drainage sluices. Ulcer prevalences outside the two IJsselmeer Lake sluices (Den Oever and Kornwerderzand) declined in this period from approximately 30% to 10% for medium-sized fish. Other skin diseases have also displayed a downward trend at both sites in recent years, with prevalences falling sharply to below 1%. Elsewhere in the Wadden Sea and the Ems-Dollard estuary, disease prevalences have declined towards natural background levels (< 1%). It is concluded that skin diseases, especially ulcers, are useful indicators of environmental quality in the Wadden Sea.

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.

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.

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)

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

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.

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.

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.

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.

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.

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.

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.

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....

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.

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.

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...

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

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...

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.

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.

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.

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....

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....

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}.

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

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)

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.

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.

Complementary approaches to diagnosing marine diseases: a union of the modern and the classic

Science.gov (United States)

Burge, Colleen A.; Friedman, Carolyn S.; Getchell, Rodman G.; House, Marcia; Lafferty, Kevin D.; Mydlarz, Laura D.; Prager, Katherine C.; Sutherland, Kathryn P.; Renault, Tristan; Kiryu, Ikunari; Vega-Thurber, Rebecca

2016-01-01

Linking marine epizootics to a specific aetiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative real-time PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease.

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.

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.

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

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.

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.

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.

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.

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

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…

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.

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.

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.

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.

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.

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.)

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

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)

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.

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...

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.

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.

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.

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.

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)

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

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...

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.

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.)

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

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)

A SKIN TEST FOR DETECTING GROUP C HEMOLYTIC STREPTOCOCCAL INFECTION CAUSING EPIZOOTIC LYMPHADENITIS IN GUINEA PIGS : APPLICATIONS IN SELECTING BREEDING STOCK.

Science.gov (United States)

Moen, J K

1936-09-30

1. A skin test with a crude bacterial extract prepared from group C (Lancefield) hemolytic streptococci was used as a means of detecting possible carriers of the streptococcus causing epizootic lymphadenitis in guinea pigs. A positive test similar to a positive tuberculin reaction was considered presumptive evidence of present or recent infection with this streptococcus. 2. 20 positive reactors were found in 330 supposedly normal guinea pigs. 3. 195 negatively reacting animals were used as a breeding stock which yielded 1,296 progeny over a period of 15 months. None of the breeding stock or their progeny showed evidence of spontaneous lymphadenitis. Skin tests of 100 of the progeny were all negative. 4. The use of this skin test as a means of obtaining guinea pig breeding stock free of the streptococcus causing spontaneous lymphadenitis is suggested.

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.

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)

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

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

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

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.

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.

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.

Shell Shape Analysis and Spatial Allometry Patterns of Manila Clam (Ruditapes philippinarum in a Mesotidal Coastal Lagoon

Directory of Open Access Journals (Sweden)

Nathalie Caill-Milly

2012-01-01

Full Text Available While gradual allometric changes of shells are intrinsically driven by genotype, morphometrical shifts can also be modulated by local environmental conditions. Consequently the common use of a unique dimension (usually length to assess bivalves’ growth may mask phenotypic differences in valve shape among populations. A morphometric exhaustive study was conducted on Manila clam, Ruditapes philippinarum, by acquiring data in the French Arcachon Bay (intrasite phenotypic variability and by comparing with other sites in the literature (intersite phenotypic variability. 2070 shells were subsampled, weighted, and automatically measured using TNPC software. Some ratios’ values indicate a relatively round and globular shape shell in comparison with other sites confirming poor conditions for some individuals. Among adult clams, three main morphological groups were identified and discussed according to spatial considerations. Allometric relations for pairs of shell descriptors were determined by testing classical linear and piecewise regression models on log-transformed relation of Huxley. A significant shape change correlated to size was observed; it corresponds to the second year of life of the clam. Relationships between density, disease, and shell shape are demonstrated and discussed related to other potential factors affecting shell shape. Finally, consequences on population regulation are addressed.

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

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)

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...

Botanical pesticides effect from shells of bean’s cashew nut on biological agents of trichoderma sp. and gliocladium sp.

Science.gov (United States)

Bande, L. O. S.; Mariadi; Gusnawaty, HS; Nuriadi; Trisulpa, L.; Rahmania

2018-02-01

A shell of cashew nut (Anacardium occidentanle) has contained Cashew Nut Shell Liquid (CNSL) that is used as botanical pesticides. CNSL oil consists of active substance such as anacardat acid, cardol and cardanol. Utilization of the pesticides from shells of cashew nut to control pests and diseases of plants would be affected on biological agents. The objective of this research was to investigate pesticides inhibition on the increase of mycelium Trichoderma sp. and Gliocladium sp. by in vitro method. The tested concentration sample consisted of 0.0% (control), 2.5%, 7.5% and 10.0% in PDA media. The results of this research showed that 2.5% botanical pesticides concentration could minimize mycelium of Trichoderma sp. and Gliocladium sp. 22.73% and 21.04% respectively and also the increase shells of cashew extract could be affected the increase of mycelium inhibition. The extract with 2.5% concentration was the recommended concentration to control of fruit rot diseases and if concentration was 10.0% then its inhibition become 54.98% and 49.35%, respectively. The results proved that uncontrolled utilization of the pesticides could be affected on decrease of Trichoderma sp. and Gliocladium sp. growth.

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.

Controlled-release and preserved bioactivity of proteins from (self-assembled core-shell double-walled microspheres

Directory of Open Access Journals (Sweden)

Yuan W

2012-01-01

Full Text Available Weien Yuan1,2, Zhenguo Liu11Department of Neurology, Xinhua Hospital, affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 2School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of ChinaAbstract: In order to address preserved protein bioactivities and protein sustained-release problems, a method for preparing double-walled microspheres with a core (protein-loaded nanoparticles with a polymer-suspended granule system-formed core and a second shell (a polymer-formed shell for controlled drug release and preserved protein bioactivities has been developed using (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W phases. The method, based on our previous microsphere preparation method (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W, employs different concentric poly(D,L-lactide-co-glycolide, poly(D,L-lactide, and protein-loaded nanoparticles to produce a suspended liquid which then self-assembles to form shell-core microspheres in the hydrophilic oil phase, which are then solidified in the water phase. Variations in the preparation parameters allowed complete encapsulation by the shell phase, including the efficient formation of a poly(D,L-lactide shell encapsulating a protein-loaded nanoparticle-based poly(D,L-lactide-co-glycolide core. This method produces core-shell double-walled microspheres that show controlled protein release and preserved protein bioactivities for 60 days. Based upon these results, we concluded that the core-shell double-walled microspheres might be applied for tissue engineering and therapy for chronic diseases, etc.Keywords: protein delivery, protein stability, core-shell microspheres, dextran nanoparticles

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.

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)

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

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.

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

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.

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

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

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.

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

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)

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.

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.

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.

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.

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.

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.

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.

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...

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.

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

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.

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.

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.

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

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.

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

Epizootia de raiva na área urbana de Ribeirão Preto, SP, Brasil Rabies epizootic in the urban area of Ribeirão Preto, São Paulo, Brazil

Directory of Open Access Journals (Sweden)

Afonso Dinis Costa Passos

1998-10-01

Full Text Available Este estudo objetiva descrever uma epizootia de raiva iniciada em 1995 na área urbana de Ribeirão Preto e estudar os fatores que propiciaram o seu aparecimento. Foram revistos e estudados todos os casos laboratorialmente confirmados de raiva animal ocorridos a partir de janeiro de 1995. Paralelamente, foram levantadas informações relativas à cobertura vacinal e às atividades de vigilância. Em 1995, além de um caso humano, ocorreram 58 casos de raiva animal (54 cães, três gatos e um morcego. Em 1996, foram observados vinte casos (18 cães e dois gatos. A concentração de casos foi diferente conforme as áreas distritais, com maiores valores sendo observados nas regiões mais pobres da cidade. A distribuição de casos não variou conforme os meses do ano. Baixas coberturas vacinais e quase ausência de atividades de vigilância, traduzida pelo não-envio sistemático de amostras para exames laboratoriais nos anos imediatamente anteriores a 1995, foram os fatores determinantes do aparecimento da epizootia. Este evento ilustra os riscos de se negligenciar a profilaxia permanente da raiva, mesmo numa cidade com razoável estrutura dos serviços de saúde e localizada numa das áreas de maior desenvolvimento econômico do País.This report describes some epidemiological aspects of a rabies epizootic that started in 1995 in the urban area of Ribeirão Preto, SP, Brazil, and discusses its main causes. All laboratory confirmed cases were described according to a set of epidemiological variables. Simultaneously, information was raised concerning rabies vaccine coverage and epidemiological surveillance activities. In addition to one human case, 58 rabid animals were confirmed in 1995 (54 dogs, 3 cats. and 1 bat. There were 20 cases in 1996 (18 dogs and 2 cats. Geographical distribution was uneven in the city, with higher concentrations observed in the Western, Northern, and Southwestern sections, corresponding to the poorest areas. No seasonal

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...

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)

Biotypes and ScM types of isolates of Streptococcus canis from diseased and healthy cats.

Science.gov (United States)

Timoney, J F; Velineni, S; Ulrich, B; Blanchard, P

2017-04-08

Lancefield group G Streptococcus canis is a component of the normal urogenital and pharyngeal flora of the cat. It is also frequently implicated in epizootics of severe disease in closed cat colonies and animal shelters. Given the importance of S canis as a feline pathogen and relative lack of published information on characteristics potentially associated with virulence, the authors have compared isolates from healthy and diseased cats in New York and California using fermentation profiles (biotype) and ScM sequences. With few exceptions, isolates associated with disease were biotype 1. Four alleles of scm were identified of which type 1 dominated in diseased cats. Type 4 allelic variants were found only in healthy cats and all but one were biotype 2. Type 2 and 3 alleles showed extensive N-terminal variation suggesting a plasminogen-binding site as found on the type 1 allele was absent. Cat antisera to ScM were opsonobactericidal, and these potentially protective antibodies increased during convalescence. British Veterinary Association.

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

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.

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)

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.)

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.

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.)

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

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

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.

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.

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.

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.

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.

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.

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

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.)

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%.

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.)

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.

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)

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

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.

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

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.

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.

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.

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.)

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

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.

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)

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.

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

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

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.

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...

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

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.

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

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

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.

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.

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.

Status of aspergillosis and sea fan populations in Curaçao ten years after the 1995 Caribbean epizootic

Directory of Open Access Journals (Sweden)

M. M Nugues

2006-12-01

Full Text Available In 1995, a survey of sea fan corals was conducted in Curaçao during a Caribbean-wide outbreak of the sea fan disease aspergillosis. The survey was repeated in 2005 using the same methodology and identical sites to examine changes in sea fan populations 10 years after the initial epizootic. Necrotic lesions typical of aspergillosis were present on as many sea fans in 2005 as in 1995 (mean ± SE: 52 ± 6 vs 43 ± 10%. The disease also showed no significant variation in virulence (9.6 ± 1.2 vs 8.8 ± 1.0% tissue loss per diseased colony. However, the average number of sea fan colonies per 10 m² decreased from 2.7 ± 1.1 to 0.7 ± 0.2 over the 10-year period, a decline of almost 75%. This decrease occurred for all colony sizes, but was more pronounced among small colonies, resulting in an overall trend of domination by large colonies. These results support that aspergillosis can have a significant, long-term impact on sea fan population size and structure. The continued presence of the disease in 2005 could be contributing to reduced recruitment and/or selective mortality among the smallest colonies. This study provides no indication that host resistance against aspergillosis could reverse the decline of Caribbean sea fan corals. Rev. Biol. Trop. 54 (Suppl. 3: 153-160. Epub 2007 Jan. 15.En 1995, se realizó un sondeo de los abanicos de mar durante un brote de aspergilosis, una enfermedad de abanicos de mar extendida en todo el Caribe. En el año 2005 se repitió el sondeo utilizando exactamente la misma metodología y los mismos sitios para examinar cambios en las poblaciones tras 10 años del inicio del brote. Se presentaron lesiones necróticas típicas de la aspergilosis en tantos abanicos en el 2005, como en 1995 (promedio ± ES: 52 ± 6 vs 43 ± 10%. La enfermedad tampoco mostró variaciones significativas en la virulencia (9.6 ± 1.2 vs 8.8 ± 1.0%, pérdida de tejido por colonia enferma. Sin embargo, el número promedio de colonias de

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.

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

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.

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.

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

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 ...

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.

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

Distribution of haemic neoplasia of soft-shelled clams in Prince Edward Island: an examination of anthropogenic factors and effects of experimental fungicide exposure.

Science.gov (United States)

Mateo, D R; MacCallum, G S; McGladdery, S E; Davidson, J

2016-05-01

Haemic neoplasia was first considered a disease of concern for soft-shell clams in Prince Edward Island (PEI) when it was diagnosed as the cause of mass mortalities in 1999. The aetiology of the disease remains elusive, but has been associated with environmental degradation. In this study, a 2-year (2001-2002) geographic and seasonal survey was conducted for haemic neoplasia, using histology, in soft-shell clams from PEI. In addition, using geographic information system, the association between anthropogenic factors in the watersheds at sites affected by haemic neoplasia and the prevalence of the disease was investigated. Finally, histopathological changes were assessed in soft-shell clams experimentally exposed to four concentrations of chlorothalonil for 27 days. Haemic neoplasia could not be induced at any concentration of chlorothalonil. Clams exposed to a concentration of 1000 μg L(-1) of the fungicide, however, exhibited an LC50 of 17 days. Although this information provides additional toxicity information (LC50) for soft-shell clams, further experiments are required to assess longer term exposure to the fungicide. The highest prevalences of haemic neoplasia in PEI were found in North River and Miscouche (28.3-50.9% and 33.0-77.8%, respectively). No clear seasonal patterns were found. There was a correlation between haemic neoplasia prevalence and watersheds with a high percentage of potato acreage and forest coverage (P = 0.026 and P = 0.045, respectively), suggesting a link between anthropogenic activity and the prevalence of the disease. © 2015 John Wiley & Sons Ltd.

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.

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.

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

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)

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.

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

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.

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)

KEYNOTE PRESENTATION AND ROUNDTABLE SESSION 4. CRAYFISH PATHOLOGY IN EUROPE:PAST, PRESENT AND A PROGRAMME FOR THE FUTURE

Directory of Open Access Journals (Sweden)

EDGERTON B. F.

2004-01-01

Full Text Available The devastating affects of disease on European freshwater crayfish are well known as epizootics in wild populations have occurred throughout much of Europe since the mid XVIIIe s. After protracted and rigorous debate, the cause of the disease named crayfish plague was proved to be the fungus Aphanomyces astaci in 1934. In the last 70 years, much of the research conducted in the field of crayfish pathology has concentrated on fungi, especially improving diagnostic techniques for A. astaci. Similarly, diagnostic responses to epizootics in European crayfish have concentrated almost entirely on fungal isolation and/or identification. On the other hand, viruses have proved to be the most important pathogens in the growing global crustacean aquaculture and fishery industries. Rickettsia-like organisms (RLO are also important. Critically, diagnostic techniques necessary to detect the full range of potential pathogens of crayfish are rarely utilized in the field of crayfish pathology in Europe. Histopathological analysis, required for the diagnosis of infections by viruses and RLOs, is absent from most European studies. Epizootics unrelated to A. astaci in European crayfish and epizootics in introduced American crayfish species highlight the inadequate current state of knowledge in the field. Presently, the field is ill-equipped to determine the cause(s of these epizootics. Moreover, crayfish conservation strategies may be undermined and even detrimental to the longterm goals; eg., stocking programs may spread undetected pathogens. Therefore, critical limitations in the field of crayfish pathology have major repercussions in management of freshwater crayfish. Guiding principles and a concept for a trans-European Community research and education program were developed to address this serious issue and are presented herein.

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.

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

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

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.)

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.

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.

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

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.

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)

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...

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.

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

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.

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

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...

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.

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...

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.

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.

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)

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

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.)

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.

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.

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.

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

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.

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.

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

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

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.

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.)

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.

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

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

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

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...

Toward an integrative molecular approach to wildlife disease.

Science.gov (United States)

DeCandia, Alexandra L; Dobson, Andrew P; vonHoldt, Bridgett M

2018-01-29

Pathogens pose serious threats to human health, agricultural investment, and biodiversity conservation through the emergence of zoonoses, spillover to domestic livestock, and epizootic outbreaks. As such, wildlife managers are often tasked with mitigating the negative effects of disease. Yet, parasites form a major component of biodiversity that often persist. This is due to logistical challenges of implementing management strategies and to insufficient understanding of host-parasite dynamics. We advocate for an inclusive understanding of molecular diversity in driving parasite infection and variable host disease states in wildlife systems. More specifically, we examine the roles of genetic, epigenetic, and commensal microbial variation in disease pathogenesis. These include mechanisms underlying parasite virulence and host resistance and tolerance, and the development, regulation, and parasite subversion of immune pathways, among other processes. Case studies of devil facial tumor disease in Tasmanian devils (Sarcophilus harrisii) and chytridiomycosis in globally distributed amphibians exemplify the broad range of questions that can be addressed by examining different facets of molecular diversity. For particularly complex systems, integrative molecular analyses present a promising frontier that can provide critical insights necessary to elucidate disease dynamics operating across scales. These insights enable more accurate risk assessment, reconstruction of transmission pathways, discernment of optimal intervention strategies, and development of more effective and ecologically sound treatments that minimize damage to the host population and environment. Such measures are crucial when mitigating threats posed by wildlife disease to humans, domestic animals, and species of conservation concern. © 2018 Society for Conservation Biology.

Did vaccination slow the spread of bluetongue in France?

Directory of Open Access Journals (Sweden)

Maryline Pioz

Full Text Available Vaccination is one of the most efficient ways to control the spread of infectious diseases. Simulations are now widely used to assess how vaccination can limit disease spread as well as mitigate morbidity or mortality in susceptible populations. However, field studies investigating how much vaccines decrease the velocity of epizootic wave-fronts during outbreaks are rare. This study aimed at investigating the effect of vaccination on the propagation of bluetongue, a vector-borne disease of ruminants. We used data from the 2008 bluetongue virus serotype 1 (BTV-1 epizootic of southwest France. As the virus was newly introduced in this area, natural immunity of livestock was absent. This allowed determination of the role of vaccination in changing the velocity of bluetongue spread while accounting for environmental factors that possibly influenced it. The average estimated velocity across the country despite restriction on animal movements was 5.4 km/day, which is very similar to the velocity of spread of the bluetongue virus serotype 8 epizootic in France also estimated in a context of restrictions on animal movements. Vaccination significantly reduced the propagation velocity of BTV-1. In comparison to municipalities with no vaccine coverage, the velocity of BTV-1 spread decreased by 1.7 km/day in municipalities with immunized animals. For the first time, the effect of vaccination has been quantified using data from a real epizootic whilst accounting for environmental factors known to modify the velocity of bluetongue spread. Our findings emphasize the importance of vaccination in limiting disease spread across natural landscape. Finally, environmental factors, specifically those related to vector abundance and activity, were found to be good predictors of the velocity of BTV-1 spread, indicating that these variables need to be adequately accounted for when evaluating the role of vaccination on bluetongue spread.

Genetic and anatomic determinants of enzootic Venezuelan equine encephalitis virus infection of Culex (Melanoconion taeniopus.

Directory of Open Access Journals (Sweden)

Joan L Kenney

Full Text Available Venezuelan equine encephalitis (VEE is a re-emerging, mosquito-borne viral disease with the potential to cause fatal encephalitis in both humans and equids. Recently, detection of endemic VEE caused by enzootic strains has escalated in Mexico, Peru, Bolivia, Colombia and Ecuador, emphasizing the importance of understanding the enzootic transmission cycle of the etiologic agent, VEE virus (VEEV. The majority of work examining the viral determinants of vector infection has been performed in the epizootic mosquito vector, Aedes (Ochlerotatus taeniorhynchus. Based on the fundamental differences between the epizootic and enzootic cycles, we hypothesized that the virus-vector interaction of the enzootic cycle is fundamentally different from that of the epizootic model. We therefore examined the determinants for VEEV IE infection in the enzootic vector, Culex (Melanoconion taeniopus, and determined the number and susceptibility of midgut epithelial cells initially infected and their distribution compared to the epizootic virus-vector interaction. Using chimeric viruses, we demonstrated that the determinants of infection for the enzootic vector are different than those observed for the epizootic vector. Similarly, we showed that, unlike A. taeniorhynchus infection with subtype IC VEEV, C. taeniopus does not have a limited subpopulation of midgut cells susceptible to subtype IE VEEV. These findings support the hypothesis that the enzootic VEEV relationship with C. taeniopus differs from the epizootic virus-vector interaction in that the determinants appear to be found in both the nonstructural and structural regions, and initial midgut infection is not limited to a small population of susceptible cells.

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

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...

Synthesis and characterization of fluorinated magnetic core-shell nanoparticles for inhibition of insulin amyloid fibril formation

International Nuclear Information System (INIS)

Skaat, Hadas; Margel, Shlomo; Belfort, Georges

2009-01-01

Maghemite (γ-Fe 2 O 3 ) magnetic nanoparticles of 15.0 ± 2.1 nm are formed by nucleation followed by controlled growth of maghemite thin films on gelatin-iron oxide nuclei. Uniform magnetic γ-Fe 2 O 3 /poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) (γ-Fe 2 O 3 /PHFBA) core-shell nanoparticles are prepared by emulsion polymerization of the fluorinated monomer 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) in the presence of the maghemite nanoparticles. The kinetics of the insulin fibrillation process in the absence and in the presence of the γ-Fe 2 O 3 /PHFBA core-shell nanoparticles are elucidated. A significant direct slow transition from α-helix to β-sheets during insulin fibril formation is observed in the presence of the γ-Fe 2 O 3 /PHFBA nanoparticles. This is in contradiction to our previous manuscript, which illustrated that the γ-Fe 2 O 3 core nanoparticles do not affect the kinetics of the formation of the insulin fibrils, and to other previous publications that describe acceleration of the fibrillation process by using various types of nanoparticles. These core-shell nanoparticles may therefore be also useful for the inhibition of conformational changes of other amyloidogenic proteins that lead to neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, mad cow and prion diseases.

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.

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

Soft shell clams Mya arenaria with disseminated neoplasia demonstrate reverse transcriptase activity

Science.gov (United States)

House, M.L.; Kim, C.H.; Reno, P.W.

1998-01-01

Disseminated neoplasia (DN), a proliferative cell disorder of the circulatory system of bivalves, was first reported in oysters in 1969. Since that time, the disease has been determined to be transmissible through water-borne exposure, but the etiological agent has not been unequivocally identified. In order to determine if a viral agent, possibly a retrovirus, could be the causative agent of DN, transmission experiments were performed, using both a cell-free filtrate and a sucrose gradient-purified preparation of a cell-free filtrate of DN positive materials. Additionally, a PCR-enhanced reverse transcriptase assay was used to determine if reverse transcriptase was present in tissues or hemolymph from DN positive soft shell clams Mya arenaria. DN was transmitted to healthy clams by injection with whole DN cells, but not with cell-free flitrates prepared from either tissues from DN positive clams, or DN cells. The cell-free preparations from DN-positive tissues and hemolymph having high levels of DN cells in circulation exhibited positive reactions in the PCR-enhanced reverse transcriptase assay. Cell-free preparations of hemolymph from clams having low levels of DN (<0.1% of cells abnormal), hemocytes from normal soft shell clams, and normal soft shell clam tissues did not produce a positive reaction in the PCR enhanced reverse transcriptase assay.

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.

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...

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)

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.

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.

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...

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.

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

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.

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

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

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

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)

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.

Entomopathogenic fungi for mosquito control: A review

NARCIS (Netherlands)

Scholte, E.J.; Knols, B.G.J.; Samson, R.A.; Takken, W.

2004-01-01

Fungal diseases in insects are common and widespread and can decimate their populations in spectacular epizootics. Virtually all insect orders are susceptible to fungal diseases, including Dipterans. Fungal pathogens such as Lagenidium, Coelomomyces and Culicinomyces are known to affect mosquito

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....

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)

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

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

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

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...

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

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

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

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

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.

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...

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.

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

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

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.

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.))

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)

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.

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.)

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.

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.

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.

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.

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.

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.

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.

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

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

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)

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.

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.

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

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

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

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.

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

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...

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....

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.

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...

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.

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

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.)

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.)

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

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

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.

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.

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.

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

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.

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.

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.

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)

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.

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...

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.

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%).

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.

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

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.

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.

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

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.

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

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

Synthesis and characterization of fluorinated magnetic core-shell nanoparticles for inhibition of insulin amyloid fibril formation

Energy Technology Data Exchange (ETDEWEB)

Skaat, Hadas; Margel, Shlomo [Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900 (Israel); Belfort, Georges [Howard P Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)], E-mail: ch348@mail.biu.ac.il, E-mail: belfog@rpi.edu, E-mail: Shlomo.margel@mail.biu.ac.il

2009-06-03

Maghemite ({gamma}-Fe{sub 2}O{sub 3}) magnetic nanoparticles of 15.0 {+-} 2.1 nm are formed by nucleation followed by controlled growth of maghemite thin films on gelatin-iron oxide nuclei. Uniform magnetic {gamma}-Fe{sub 2}O{sub 3}/poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) ({gamma}-Fe{sub 2}O{sub 3}/PHFBA) core-shell nanoparticles are prepared by emulsion polymerization of the fluorinated monomer 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) in the presence of the maghemite nanoparticles. The kinetics of the insulin fibrillation process in the absence and in the presence of the {gamma}-Fe{sub 2}O{sub 3}/PHFBA core-shell nanoparticles are elucidated. A significant direct slow transition from {alpha}-helix to {beta}-sheets during insulin fibril formation is observed in the presence of the {gamma}-Fe{sub 2}O{sub 3}/PHFBA nanoparticles. This is in contradiction to our previous manuscript, which illustrated that the {gamma}-Fe{sub 2}O{sub 3} core nanoparticles do not affect the kinetics of the formation of the insulin fibrils, and to other previous publications that describe acceleration of the fibrillation process by using various types of nanoparticles. These core-shell nanoparticles may therefore be also useful for the inhibition of conformational changes of other amyloidogenic proteins that lead to neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, mad cow and prion diseases.

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

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

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

Reptiles as potential vectors and hosts of the amphibian pathogen Batrachochytrium dendrobatidis in Panama.

Science.gov (United States)

Kilburn, Vanessa L; Ibáñez, Roberto; Green, David M

2011-12-06

Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.

Changes in Caribbean coral disease prevalence after the 2005 bleaching event.

Science.gov (United States)

Cróquer, Aldo; Weil, Ernesto

2009-11-16

Bleaching events and disease epizootics have increased during the past decades, suggesting a positive link between these 2 causes in producing coral mortality. However, studies to test this hypothesis, integrating a broad range of hierarchical spatial scales from habitats to distant localities, have not been conducted in the Caribbean. In this study, we examined links between bleaching intensity and disease prevalence collected from 6 countries, 2 reef sites for each country, and 3 habitats within each reef site (N = 6 x 2 x 3 = 36 site-habitat combinations) during the peak of bleaching in 2005 and a year after, in 2006. Patterns of disease prevalence and bleaching were significantly correlated (Rho = 0.58, p = 0.04). Higher variability in disease prevalence after bleaching occurred among habitats at each particular reef site, with a significant increase in prevalence recorded in 4 of the 10 site-habitats where bleaching was intense and a non-significant increase in disease prevalence in 18 out of the 26 site-habitats where bleaching was low to moderate. A significant linear correlation was found (r = 0.89, p = 0.008) between bleaching and the prevalence of 2 virulent diseases (yellow band disease and white plague) affecting the Montastraea species complex. Results of this study suggest that if bleaching events become more intense and frequent, disease-related mortality of Caribbean coral reef builders could increase, with uncertain effects on coral reef resilience.

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.

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.)

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

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

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 .

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.

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

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.

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.

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.

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.

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.

Atomic mass formula with linear shell terms