Temperature evaluation in ex-vivo bovine bones submitted to drilling processes

A necrose óssea induzida durante o processo de furação é um fenómeno frequente que contribui para problemas pós-operatórios. O calor de fricção gerado pelo contato entre a broca e a parede do furo é inevitável. No entanto, a utilização de técnicas avançadas para a obtenção do registo térmico durante a furação óssea é importante para a garantia da qualidade durante a furação. O objetivo deste estudo é apresentar dois métodos experimentais diferentes para analisar as condições de furação que geram as temperaturas mais baixas, evitando a ocorrência da necrose óssea. Foram utilizados ossos de bovino ex-vivo para simular o processo de furação considerando os efeitos do diâmetro da broca, velocidade de rotação e velocidade de avanço. Foram realizados diferentes testes experimentais para avaliar a sua repetibilidade. Os resultados identificaram o diâmetro da broca como o parâmetro mais crítico na indução de temperaturas mais elevadas durante a furação óssea.This research was supported by the Portuguese Foundation of Science and Technology under the research project UID/EMS/50022/2013. The third author acknowledges the funding of Project NORTE-01-0145-FEDER-000022-SciTech -Science and Technology for Competitive and Sustainable Industries, co-financed by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER).info:eu-repo/semantics/publishedVersio

GEM operation in double-phase xenon

http://www.sciencedirect.com/science/article/B6TJM-4T7F5JF-5/2/897502f8049abd8c2dd3dffc3821f0f

A survey of energy loss calculations for heavy ions between 1 and 100 keV

The original Lindhard-Scharff-Schi{\o}tt (LSS) theory and the more recent Tilinin theory for calculating the nuclear and electronic stopping powers of slow heavy ions are compared with predictions from the SRIM code by Ziegler. While little discrepancies are present for the nuclear contribution to the energy loss, large differences are found in the electronic one. When full ion recoil cascade simulations are tested against the elastic neutron scattering data available in the literature, it can be concluded that the LSS theory is the more accurate.Comment: Presented at the 10th International Symposium on Radiation Physics, 17-22 September, 2006, Coimbra, Portugal; style corrections, small change to fig.

A model of the reflection distribution in the vacuum ultra violet region

A reflection model with three components, a specular spike, a specular lobe and a diffuse lobe is discussed. This model was successfully applied to describe reflection of xenon scintillation light (175 nm) by PTFE and other fluoropolymers and can be used for Monte Carlo simulation and analysis of scintillation detectors. The measured data favors a Trowbridge-Reitz distribution function of ellipsoidal micro-surfaces. The intensity of the coherent reflection increases with increasing angle of incidence, as expected, since the surface appears smoother at grazing angles. The total reflectance obtained for PTFE is about 70% for VUV light at normal incidence in vacuum and estimated to be up to 100% in contact with liquid xenon

Scintillation efficiency of liquid xenon for nuclear recoils with the energy down to 5 keV

The scintillation efficiency of liquid xenon for nuclear recoils has been measured to be nearly constant in the recoil energy range from 140 keV down to 5 keV. The average ratio of the efficiency for recoils to that for gamma-rays is found to be 0.19+-0.02.Comment: 13 pages, 5 figure

Perspectives for Positron Emission Tomography with RPCs

In this study we address the feasibility and main properties of a positron emission tomograph (PET) based on RPCs. The concept, making use of the converter-plate principle, takes advantage of the intrinsic layered structure of RPCs and its simple and economic construction. The extremely good time and position resolutions of RPCs also allow the TOF-PET imaging technique to be considered. Monte-Carlo simulations, supported by experimental data, are presented and the main advantages and drawbacks for applications of potential interest are discussed.Comment: Presented at "RPC2001-VI Workshop on Resistive Plate Chambers and Related Detectors", Coimbra, Portugal, 26-27 November 2001 (5 pages

Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model

It is shown that exciton swapping between two graphene sheets may occur under specific conditions. A magnetically tunable optical filter is described to demonstrate this new effect. Mathematically, it is shown that two turbostratic graphene layers can be described as a "noncommutative" two-sheeted (2+1)-spacetime thanks to a formalism previously introduced for the study of braneworlds in high energy physics. The Hamiltonian of the model contains a coupling term connecting the two layers which is similar to the coupling existing between two braneworlds at a quantum level. In the present case, this term is related to a K-K' intervalley coupling. In addition, the experimental observation of this effect could be a way to assess the relevance of some theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical Journal

Agrobacterium-mediated transformation of the terpenoid indole alkaloid-producing plant species Tabernaemontana pandacaqui

Plants of the Apocynaceae family produce a wide range of terpenoid indole alkaloids (TIAs) which have important pharmaceutical applications. Studies of the molecular mechanisms controlling TIA biosynthesis may eventually provide possibilities to improve product yield by genetic modification of plants or cell cultures. However, these studies suffer from the lack of transformation/regeneration protocols for Apocynaceae plants. We chose to study the feasibility of Agrobacterium tumefaciens-mediated transformation of Tabernaemontana pandacaqui, because of the availability of an efficient regeneration procedure for this member of the Apocynaceae family. A procedure to produce transgenic T. pandacaqui plants was established, albeit with low efficiency. Transgenic expression was demonstrated of an intron-containing β-glucuronidase reporter gene and of a gene coding for the TIA biosynthetic enzyme strictosidine synthase from Catharanthus roseus, another Apocynaceae species.info:eu-repo/semantics/publishedVersio

Agrobacterium-mediated transformation of the terpenoid indole alkaloid-producing plant species Tabernaemontana pandacaqui

Plants of the Apocynaceae family produce a wide range of terpenoid indole alkaloids (TIAs) which have important pharmaceutical applications. Studies of the molecular mechanisms controlling TIA biosynthesis may eventually provide possibilities to improve product yield by genetic modification of plants or cell cultures. However, these studies suffer from the lack of transformation/regeneration protocols for Apocynaceae plants. We chose to study the feasibility of Agrobacterium tumefaciens-mediated transformation of Tabernaemontana pandacaqui, because of the availability of an efficient regeneration procedure for this member of the Apocynaceae family. A procedure to produce transgenic T. pandacaqui plants was established, albeit with low efficiency. Transgenic expression was demonstrated of an intron-containing β-glucuronidase reporter gene and of a gene coding for the TIA biosynthetic enzyme strictosidine synthase from Catharanthus roseus, another Apocynaceae species.info:eu-repo/semantics/publishedVersio

Measurement of single electron emission in two-phase xenon

We present the first measurements of the electroluminescence response to the emission of single electrons in a two-phase noble gas detector. Single ionization electrons generated in liquid xenon are detected in a thin gas layer during the 31-day background run of the ZEPLIN-II experiment, a two-phase xenon detector for WIMP dark matter searches. Both the pressure dependence and magnitude of the single-electron response are in agreement with previous measurements of electroluminescence yield in xenon. We discuss different photoionization processes as possible cause for the sample of single electrons studied in this work. This observation may have implications for the design and operation of future large-scale two-phase systems.Comment: 11 pages, 6 figure