Field-effect tunneling transistor based on vertical graphene heterostructures     

Britnell L  Gorbachev RV  Jalil R  Belle BD  Schedin F  Mishchenko A  Georgiou T  Katsnelson MI  Eaves L  Morozov SV  Peres NM  Leist J  Geim AK  Novoselov KS  Ponomarenko LA 《Science (New York, N.Y.)》2012,335(6071):947-950

An obstacle to the use of graphene as an alternative to silicon electronics has been the absence of an energy gap between its conduction and valence bands, which makes it difficult to achieve low power dissipation in the OFF state. We report a bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness. Our prototype devices are graphene heterostructures with atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier. They exhibit room-temperature switching ratios of ≈50 and ≈10,000, respectively. Such devices have potential for high-frequency operation and large-scale integration.  相似文献   

Temporal stability of vigor in rubber tree genotypes in the pre- and post-tapping phases using different methods     

Lígia Regina Lima Gouvêa  Guilherme Augusto Peres Silva  Cecília Khusala Verardi  Juliano Quarteroli Silva  Erivaldo José Scaloppi-Junior  Paulo de Souza Gonçalves 《Euphytica》2012,186(3):625-634

Vigor is important in rubber tree cropping because of its association with early latex exploitation, resistance to wind breakage and wood production. The objective of the present study was to assess the vigor stability of 25 rubber tree genotypes in the pre- and post-tapping phases using different methods. A randomized block design was used with three replications and six plants per plot. Seven annual trunk girth increments were used in the pre-tapping and six in the post-tapping phases. Stability was assessed by the methods by Wricke, Eberhart and Russell, Lin and Binns, and the AMMI statistical model (Model Additive Main Effects and Multiplicative Interaction). The association among the different stability parameters ωι, , Pi, and IPCA 1 was verified by the Spearman correlation. Joint ANOVA showed highly significant effects for genotypes, years, and genotypes × years interaction in the two phases. In the pre-tapping phase, the IAC 311 genotype was stable in all the methods and in the post-tapping presented stability in Eberhart and Russell, Wricke, and AMMI. In the post-tapping phase, the IAC 312 genotype was stable in Eberhart and Russell, AMMI and Lin and Binns. While in the pre-tapping the correlations were positive and significant among all the parameters, in the post-tapping it only occurred between ωι with and ωι with IPCA 1. In the stability assessment of rubber tree vigor, the association among the methods depended on the assessment period. Stability methods based on different principles can show agreement in identifying stable genotypes in rubber tree vigor. The tapping procedure affected vigor stability of rubber trees.  相似文献   

Digestive enzyme activity and nutrient digestibility in meagre (Argyrosomus regius) fed increasing levels of black soldier fly meal (Hermetia illucens)     

Inês Guerreiro  Cludia R. Serra  Filipe Coutinho  Ana Couto  Carolina Castro  Fbio Rangel  Helena Peres  Pedro Pouso‐Ferreira  Elisabete Matos  Laura Gasco  Francesco Gai  Aires Oliva‐Teles  Paula Enes 《Aquaculture Nutrition》2021,27(1):142-152

The effect of partially replacing fishmeal (FM) by black soldier fly larvae meal (Hermetia meal—HM) in meagre (Argyrosomus regius) diet was evaluated for nutrient digestibility and digestive enzyme activity. For that purpose, triplicate groups of fish (18.0 ± 0.02 g) were fed during 48 days either a control diet (CTR), without HM, or one of three diets including 100, 200 and 300 g/kg of HM, replacing 17, 35 and 52% of FM, respectively. Apparent digestibility coefficients (ADCs) of dry matter, energy, protein, lysine, isoleucine, leucine, phenylalanine, alanine, glutamate, glycine and serine presented a decreasing response with increased HM inclusion. Chitin ADC was null, independent of dietary HM inclusion. Total alkaline protease activity increased while trypsin activity decreased with dietary HM inclusion. No intestinal chitinolytic activity was detected. Intestinal alkaline protease zymogram revealed nine bands with proteolytic activity against casein, with molecular weights ranging between 15 and 75 kDa. Anti‐protease activity in the intestine was not affected by dietary inclusion of HM compared to the CTR diet. Overall, it is concluded that replacement of up to 17% FM with HM (100 g/kg HM inclusion level) in meagre diets has no major adverse effects in diet digestibility and digestive enzyme activity.  相似文献   

Influence of experimental inflammatory response on hepatic hepcidin gene expression and plasma iron concentration in sheep     

Badial PR  Oliveira-Filho JP  Cunha PH  Araújo JP  Peiró JR  Divers TJ  Winand NJ  Borges AS 《Veterinary immunology and immunopathology》2011,141(1-2):157-161

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Anatomical description of arterial segments of the spleen of deer     

Peres Ferraz de Melo A  de Souza WM  Rodrigues RF  Alves FR  Rici RE  Guerra RR  Favaron PO  Miglino MA  Di Dio LJ 《Anatomia, histologia, embryologia》2011,40(4):243-248

With 2 figures SUMMARY: The anatomosurgical segmentation of the arteries of the spleen was studied in 31 deer of the species Mazama gouazoubira and Blastocerus dichotomus by means of vascular injection with latex and vinyl acetate and radiographic examination. The arteria lienalis penetrated through the hilus lienis in 87% of the cases, whereas an extrahilar artery was present in the other cases. An extraparenchymal division of the lineal artery into two, three or four segmental arteries was observed in 74% of the cases. Anastomoses between intraparenchymal arterial branches were rare and of a reduced calibre.  相似文献   

Real‐time quantitative PCR‐based detection of Coxiella burnetii in unpasteurized cow's milk sold for human consumption     

Mateus de Souza Ribeiro Mioni  Bruna Letícia Devid Ribeiro  Marina Gea Peres  Wanderson Sirley Reis Teixeira  Vanessa Cristina Pelícia  Rodrigo Garcia Motta  Marcelo Bahia Labruna  Mrcio Garcia Ribeiro  Karim Sidi‐Boumedine  Jane Megid 《Zoonoses and public health》2019,66(6):695-700

Coxiella burnetii is a zoonotic pathogen with a worldwide distribution that is responsible for Q fever in humans. It is a highly infectious bacterium that can be transmitted from cattle to humans through the consumption of unpasteurized milk. We report the molecular identification of C. burnetii in raw cow's milk being sold directly for human consumption in Brazil without official inspection or pasteurization. One hundred and twelve samples of raw milk were analysed by real‐time quantitative PCR (qPCR), and C. burnetii was detected in 3.57% (4/112) of the samples at a concentration ranging from 125 to 404 bacteria per millilitre. The identification of this zoonotic pathogen in raw milk sold directly for human consumption is a public health concern since C. burnetii can be transmitted through the oral route. This result indicates that health education and other preventive measures should be officially implemented in Brazil to prevent the spread of infection. To our knowledge, this is the first qPCR‐based detection of C. burnetii in raw milk samples from cows sold in Brazil that do not undergo official inspection or pasteurization.  相似文献   

A review of earthworm impact on soil function and ecosystem services     

M. Blouin  M. E. Hodson  E. A. Delgado  G. Baker  L. Brussaard  K. R. Butt  J. Dai  L. Dendooven  G. Peres  J. E. Tondoh  D. Cluzeau  J.‐J. Brun 《European Journal of Soil Science》2013,64(2):161-182

Biodiversity is responsible for the provision of many ecosystem services; human well‐being is based on these services, and consequently on biodiversity. In soil, earthworms represent the largest component of the animal biomass and are commonly termed ‘ecosystem engineers’. This review considers the contribution of earthworms to ecosystem services through pedogenesis, development of soil structure, water regulation, nutrient cycling, primary production, climate regulation, pollution remediation and cultural services. Although there has been much research into the role of earthworms in soil ecology, this review demonstrates substantial gaps in our knowledge related in particular to difficulties in identifying the effects of species, land use and climate. The review aims to assist people involved in all aspects of land management, including conservation, agriculture, mining or other industries, to obtain a broad knowledge of earthworms and ecosystem services.  相似文献   

Bringing home the biggest bacon: a cross-site analysis of the structure of hunter-kill profiles in Neotropical forests     

Adriano Jerozolimski  Carlos A. Peres 《Biological conservation》2003,111(3):415-425

Forest vertebrates are critical to the subsistence of many tropical forest dwellers enjoying little or no access to other sources of animal protein. Yet the ecological and socioeconomic value of forest wildlife is being undermined as many large vertebrate populations are driven to local extinction by unsustainable hunting practices. Although large mammals that are preferred by hunters are widely variable in their morphology and ecology, they share a set of life history traits, which make them particularly vulnerable to overhunting. In this paper we compile data on game harvest from 31 tribal and nontribal settlements in Neotropical forests to examine how mammal assemblages are affected by the history of hunting within settlement catchment areas. The structure of hunter-kill profiles is related to settlement age and size in an attempt to understand how changes in hunting pressure may affect prey selectivity and the structure of residual game assemblages. There was a predictable shift from a few large-bodied to several small-bodied species harvested by increasingly older villages. Settlement persistence thus explained a significant proportion of the variation in mean body mass and species richness of mammals harvested. We conclude that differences in prey species profiles obtained by subsistence hunters of different ethnic groups can be largely explained by the local depletion status of game stocks, particularly large mammals, rather than by cultural factors.  相似文献   

Effective replacement of protein‐bound amino acids by crystalline amino acids in Senegalese sole (Solea senegalensis) juveniles     

A. Pérez‐Jiménez  H. Peres  A. Oliva‐Teles 《Aquaculture Nutrition》2014,20(1):60-68

The objective of this study was to evaluate the potential of free amino acids to replace protein‐bound amino acids in diets for Solea senegalensis juveniles. For this purpose, fish with 4.26 g mean initial weight were fed during 55 days with diets containing 500 g kg^?1 protein and 100 g kg^?1 lipid, based on fish meal and fish oil as main protein and lipid sources (control diet), or diets where 20%, 35% and 50% of fish meal were replaced by crystalline amino acids, using L‐lysine HCl as lysine source. To access the efficiency of the crystalline lysine source, another diet was formulated with 35% fish meal replacement but using L‐lysine sulphate instead of L‐lysine HCl as lysine source. Overall, growth performance, feed utilization, nutrient retention, whole‐body and amino acid composition did not show significant differences among groups. In conclusion, up to 50% protein‐bound amino acids can be replaced by crystalline amino acids in diets for Senegalese sole juveniles without negative effects in fish performance. Additionally, it was shown that L‐lysine sulphate and L‐lysine‐HCl may be used interchangeably by Senegalese sole juveniles, with the potential economic benefits involved.  相似文献   

Blood chemistry profile as indicator of nutritional status in European seabass (Dicentrarchus labrax)     

Helena Peres  Sara Santos  Aires Oliva-Teles 《Fish physiology and biochemistry》2014,40(5):1339-1347

This study was carried out to establish biochemical parameters with potential diagnostic value to assess the nutritional status of healthy seabass. For that purpose, triplicate groups of seabass juveniles were submitted to different feeding protocols: fed for 14 days; fed for 7 days followed by 7 days of fasting or fasted for 14 days. At the end of the trial, body, liver and viscera were randomly sampled for proximate composition analysis. Blood was also collected and the following plasma parameters were analyzed by standard clinical methods: glucose; cholesterol; triglycerides; protein; inorganic phosphorus; calcium; magnesium; alkaline phosphatase (ALP); aspartate aminotransferase; lactate dehydrogenase; creatine phosphokinase and lipase. No major effect of feed deprivation on body composition, visceral index, perivisceral and hepatic lipid content were observed, whereas hepatosomatic index and hepatic glycogen were reduced. Previous feeding conditions strongly influenced the plasma parameters in seabass. Comparatively to the fed group, plasma glucose, cholesterol and calcium levels were reduced after 2 weeks of fasting while plasma triglycerides, protein, inorganic phosphorus and ALP attained minimum levels after 1 week of fasting. Overall, enzymatic activity parameters showed higher variability than biochemistry parameters. In conclusion, during short-term starvation (<14 days) hepatic energy depots were extensively mobilized while perivisceral and body lipids reserves were preserved. Among measured parameters, plasma protein, triglycerides, inorganic phosphorus and ALP seem to have potential as predicative diagnostic tools to assess the nutritional status of seabass and may be useful to monitor feeding practices in aquaculture. Further studies are, however, required to extend results of this study to other fish size classes.  相似文献