Out-of-plane and in-plane actuation effects on atomic-scale friction

The influence of out-of-plane and in-plane contact vibrations and temperature on the friction force acting on a sharp tip elastically pulled on a crystal surface is studied using a generalized Prandtl- Tomlinson model. The average friction force is significantly lowered in a frequency range determined by the "washboard" frequency of the stick-slip motion and the viscous damping accompanying the tip motion. An approximately linear relation between the actuation amplitude and the effective corrugation of the surface potential is derived in the case of in-plane actuation, extending a similar conclusion for out-of-plane actuation. Temperature causes an additional friction reduction with a scaling relation in formal agreement with the predictions of reaction rate theory in absence of contact vibrations. In this case the actuation effects can be described by the effective energy or, more accurately, by introducing an effective temperature.Comment: To appear in Physical Review

Lateral vibration effects in atomic-scale friction

The influence of lateral vibrations on the stick-slip motion of a nanotip elastically pulled on a flat crystal surface is studied by atomic force microscopy (AFM) measurements on a NaCl(001) surface in ultra-high vacuum. The slippage of the nanotip across the crystal lattice is anticipated at increasing driving amplitude, similarly to what is observed in presence of normal vibrations. This lowers the average friction force, as explained by the Prandtl-Tomlinson model with lateral vibrations superimposed at finite temperature. Nevertheless, the peak values of the lateral force, and the total energy losses, are expected to increase with the excitation amplitude, which may limit the practical relevance of this effect.Comment: To appear in Applied Physics Letter

Obtenção de material propagativo livre de vírus e diagnóstico de vírus em macieiras e pereiras.

Principais vírus da macieira e da pereira. Danos causados por vírus. Limpeza clonal: produção de macieiras e pereiras livres de vírus. Análises e testes de avaliação de sanidade.bitstream/item/60758/1/CNPUV-DOC.-69-09.pd

Thermal Energy Replacement Potential in a Slaughter Plant From Rumen Pellets

In this work, steam generation was studied using natural gas or rumen as energy sources in a slaughter plant that sacrifices 7500 cattle per month, with consumption 0.5749 kg/s of saturated steam at 624 kPa. For a slaughtered cow, 10.5 kg of rumen can be obtained after being dried outdoors; for its final disposal, the slaughter plant bears the costs of USD 7.2 per ton of rumen. In the study, exergy and exergoeconomic performances were compared by generating steam with a natural gas boiler with the steam generation with a rumen boiler. From this, combustion analysis, energy efficiency, exergy destruction, exergy efficiency, exergy destruction costs, and generating 1 kg of steam from the two boilers were evaluated. The study results showed that the generation of steam with rumen is less efficient than with natural gas since it presents the exergy destruction of 1175.9 kW and exergy efficiency of 26.83%. While the generation of steam with rumen boiler was obtained, with exergy destruction of 1419.9 kW and exergy efficiency of 23.29%. Exergy destruction cost and the cost of generating 1 kg of steam using rumen were $/h 7821 and 0.0073$/kg, respectively. Although the generation of steam with natural gas present the exergy destruction cost of 26285 $/h and the cost of generating steam of 0.021$/kg, this indicators are higher using natural gas as a fuel that with rumen pellets

Detection of Viruses in Apples and Pears by Real Time RT-PCR Using 5'-Hydrolysis Probes

Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple chlorotic leaf spot virus (ACLSV) and Apple mosaic virus (ApMV) are common in apples and pears and the main targets of virus elimination from propagation material. The objective of this work was to design primers and probes for a real time RT-PCR protocol for detection of the four above viruses. FAM/TAMRA-labeled probes and primers were designed by searching for highly conserved nucleotide regions in the coat protein gene of the four viruses. Infection levels in analyzed apple samples were 92.6, 96.4, 100 and 88% for ASGV, ASPV, ACLSV and ApMV, respectively. In pears, all pre-existing ASPV infections were detected. Viral infections were confirmed in a selection of commercial cultivars of apples and pear scions, and quince rootstocks, demonstrating the sensitivity and reliability of the designed primers and probes. Real time RT-PCR using 5'-labeled probes is suitable for checking sanitary quality as a routine test in certification programs

Anisotropy effects and friction maps in the framework of the 2d PT model

We present a series of numerical simulations on the friction-anisotropy behavior and stick-slip dynamics of a point mass in the framework of a 2d Prandtl-Tomlinson model. Results for three representative surface lattice are shown: square, hexagonal and honeycomb. Curves for scan angle dependence of static friction force, and kinetic one at T=0 K and T=300 K are shown. Friction force maps are computed at different directions.The authors acknowledge financial support from Spanish MINECO through Project no. FIS2011-25167, cofinanced by FEDER funds and Project no. MAT2012-34487. O.Y.F. acknowledges financial support from FPU grant by Ministerio de Ciencia e Inovación of Spain.Peer Reviewe

Detecção e caracterização molecular dos genes da proteína capsidial de ilarvírus e ampelovírus que infectam fruteiras temperadas.

Dentre os principais patógenos que incidem em fruteiras temperadas, destacam-se o Prune dwarf virus (PDV), o Apple mosaic virus (ApMV) e o Grapevine leafroll-associated virus 1 (GLRaV-1). Neste trabalho foram realizadas a detecção e a caracterização molecular dos genes da proteína capsidial de isolados destas três espécies virais. RNAs totais foram extraídos de amostras de folhas de pessegueiros, macieiras e videiras e, nas reações de RT-PCR, foram utilizados oligonucleotídeos específicos para cada espécie viral. Os cDNAs amplificados foram clonados e sequenciados. Foram verificadas altas identidades entre as sequências de nucleotídeos dos genes da proteína capsidial dos isolados brasileiros de PDV, ApMV e GLRaV-1 e isolados de outros países, independente da origem geográfica e da hospedeira. O peso molecular da proteína capsidial destes vírus foi estimado por meio de Western blot em cerca de 24kDa (PDV), 26kDa (ApMV) e 39kDa (GLRaV-1).Nota técnica

First report of grapevine pinot gris virus infecting grapevine in Brazil.

Grapevine Pinot gris virus (GPGV) has been re-ported infecting grapevines (Vitisspp.) in several countriesof the world. In this study, 19.5% of grapevine samples col-lected in Brazil and indexed for GPGV by RT-qPCR wasinfected. The complete coat protein and the partial replicase genes of two Brazilian isolates (CF-BR and ME-BR) were sequenced and exhibited very high nucleotide and deduced amino acid identities with many foreign characterized isolates of GPGVavailable in the GenBank. This is the first detection of GPGV infecting grapevines in Brazil. Keywords GPGV . Trichovirus . RT-qPCR . Real time RT-PCR. Diagnosis.Disponível em: . Acesso em: 04 set. 2017

First report on detection of three Bunya-Like Viruses in apples in Brazil.

Apple chlorotic leaf spot virus (ACLSV), apple stem grooving virus (ASGV), and apple stem pitting virus (ASPV) cause significant losses to Brazilian (BR) apple production. Looking beyond these latent viruses, high-throughput sequencing (HTS) of three samples (Vacaria, Brazil) was performed on an Illumina HiSeq X Ten platform (USA), cv. Braeburn (BB), and a BGISEQ-500 platform (China), cvs. Royal Gala (RG) and Mishima (MI)