Shape transition of germanium nanocrystals on a silicon (001) surface from pyramids to domes     

G Medeiros-Ribeiro  AM Bratkovski  TI Kamins  DAA Ohlberg  RS Williams 《Science (New York, N.Y.)》1998,279(5349):353-355

Chemical vapor deposition of germanium onto the silicon (001) surface at atmospheric pressure and 600 degrees Celsius has previously been shown to produce distinct families of smaller (up to 6 nanometers high) and larger (all approximately 15 nanometers high) nanocrystals. Under ultrahigh-vacuum conditions, physical vapor deposition at approximately the same substrate temperature and growth rate produced a similar bimodal size distribution. In situ scanning tunneling microscopy revealed that the smaller square-based pyramids transform abruptly during growth to significantly larger multifaceted domes, and that few structures with intermediate size and shape remain. Both nanocrystal shapes have size-dependent energy minima that result from the interplay between strain relaxation at the facets and stress concentration at the edges. A thermodynamic model similar to a phase transition accounts for this abrupt morphology change.  相似文献   

Self-oriented regular arrays of carbon nanotubes and their field emission properties   总被引：4，自引：0，他引：4  

S Fan  MG Chapline  NR Franklin  TW Tombler  AM Cassell  H Dai 《Science (New York, N.Y.)》1999,283(5401):512-514

The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology.  相似文献   

Enhanced resistance to bacterial infection byErwinia carotovora subsp.atroseptica in transgenic potato plants expressing the attacin or the cecropin SB-37 genes     

Patricio Arce  Mauricio Moreno  Mónica Gutierrez  Marlene Gebauer  Paola Dell’Orto  Hebert Torres  Ivette Acuña  Pauline Oliger  Alejandro Venegas  Xavier Jordana  Julio Kalazich  Loreto Holuigue 《American Journal of Potato Research》1999,76(3):169-177

Blackleg and soft rot diseases, caused by the bacteriumErwinia carotovora, are among the diseases that cause important losses in culture and storage of potato. In this paper, we introduced bacterial resistance into potato, via genes encoding for proteins with antibacterial activity. For this purpose, potato clones were transformed either with the gene encoding the acidic attacin protein fromHyalophora cecropia, or with the gene encoding the cecropin analog peptide SB37. These clones were evaluated for soft rot and blackleg resistance, after inoculation with the bacterial strainErwinia carotovora subsp.atroseptica T7. Results reported in this paper indicate that a considerable percentage of the potato clones (15–22%) showed increased resistance to bacterial infection, revealed by reduced severity of blackleg or soft rot symptoms. Expression of the transgenes was demonstrated in some of the clones by Northern blot analysis. This is the first report indicating that expression of the gene encoding for an attacin protein and for the cecropin SB-37 peptide in transgenic potato confers increased resistance to bacterial infection.  相似文献   

Growth and feeding of Patagonian pejerrey Odontesthes hatcheri reared in net cages     

Juan Pablo Hualde  Walter Damián Ceferino Torres  Pablo Moreno  Mirna Ferrada  Mariela Ana Demicheli  Leonardo Javier Molinari  Carlos Marcelo Luquet 《Aquaculture Research》2011,42(6):754-763

An experiment was performed to evaluate the performance of Patagonian pejerrey during net cage rearing in the oligomesotrophic reservoir Exequiel Ramos Mexía. Survival, growth, nutrition and reproduction were evaluated for two lots of pejerrey, initial weights 4.0 and 2.5 g, reared in net cages for 22 and 14 months respectively. Fish were stocked at 29 and 48 individuals m^?3 densities and fed with an experimental pejerrey feed. During the experiment, temperature fluctuated between 6.6 and 19.6 °C. The two lots did not show substantial differences in survival (pooled survival at the end of the experiment >80%) and the thermal‐unit growth coefficient (TGC), daily feed intake and feeding efficiency were 0.43±0.19, 1.70±0.80 and 53.6±9.9 respectively. Digestive tract analysis showed that caged pejerrey can consume substantial quantities of natural food, taking advantage of its planktivorous condition. Pejerrey showed high percentage survival, slow growth and early sexual maturation in captivity. The use of the TGC is proposed as a model for describing the growth pattern of this species and other pejerrey under culture conditions.  相似文献   

Potential role of ectoparasites (Zeuxapta seriolae and Caligus lalandei) in the transmission of pathogenic bacteria in yellowtail kingfish Seriola lalandi,inferred from cultivable microbiota and molecular analyses          下载免费PDF全文

F A Sepúlveda  J F Torres  C D Infante  M T González 《Journal of fish diseases》2017,40(7):979-985

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Bactericidal and fungicidal activity of Aspergillus ochraceus metabolites and some derivatives     

Merc Torres  Merc Balcells  Núria Sala  Vicente Sanchis  Ramon Canela 《Pest management science》1998,53(1):9-14

The bactericidal and fungicidal activities of aspyrone and asperlactone, secondary metabolites of Aspergillus ochraceus, and some aspyrone derivatives were studied. In general, aspyrone exhibited better activity than asperlactone or aspyrone derivatives. The inhibition patterns of the assayed compounds were different. Helminthosporium monoceras was the tested mould most inhibited by the studied compounds. The comparative study of the activity of the different compounds showed that the epoxy group seems to be necessary for activity against some micro-organisms. © 1998 SCI  相似文献   

Environmental fate and behaviour of the biocontrol agent Bacillus amyloliquefaciens CPA‐8 after preharvest application to stone fruit          下载免费PDF全文

Laura Vilanova  Neus Teixidó  Josep Usall  Marta Balsells‐Llauradó  Amparo Gotor‐Vila  Rosario Torres 《Pest management science》2018,74(2):375-383

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Impact of Teratosphaeria nubilosa over tree growth and survival of Eucalyptus globulus and Eucalyptus maidenii in Uruguay     

Gustavo Balmelli  Sofía Simeto  Diego Torres  Andrés Hirigoyen  Alicia Castillo  Nora Altier  Guillermo Pérez  Julio J. Diez 《New Forests》2016,47(6):829-843

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Control of citrus pathogens by protein extracts from Solanum tuberosum tubers     

I. F. Rodríguez  J. E. Sayago  S. Torres  I. C. Zampini  M. I. Isla  R. M. Ordóñez 《European journal of plant pathology / European Foundation for Plant Pathology》2015,141(3):585-595

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Search for <Emphasis Type="Italic">Salmonella</Emphasis> spp. in ostrich productive chain of Brazilian southeast region     

Oliveiro Caetano de Freitas Neto  Sonia Luisa Silva Lages  Adriano Oliveira Torres Carrasco  Angelo Berchieri Junior 《Tropical animal health and production》2009,41(8):1607-1614

We analyzed ostriches from an equipped farm located in the Brazilian southeast region for the presence of Salmonella spp. This bacterium was investigated in 80 samples of ostrich droppings, 90 eggs, 30 samples of feed and 30 samples of droppings from rodents. Additionally, at slaughter-house this bacterium was investigated in droppings, caecal content, spleen, liver and carcasses from 90 slaughtered ostriches from the studied farm. Also, blood serum of those animals were harvested and submitted to serum plate agglutination using commercial Salmonella Pullorum antigen. No Salmonella spp. was detected in any eggs, caecal content, liver, spleen, carcass and droppings from ostriches and rodents. However, Salmonella Javiana and Salmonella enterica subsp. enterica 4, 12: i:- were isolated from some samples of feed. The serologic test was negative for all samples. Good sanitary farming management and the application of HACCP principles and GMP during the slaughtering process could explain the absence of Salmonella spp. in the tested samples.  相似文献