Latent track radius of PTFE irradiated with high energy ion beam

PTFE foils were irradiated with different ion beams (Xe, Au and U) with energies up to 1.5 GeV and fluences between 1 x 10(8) and 1 x 10(13) ions/cm(2) at room temperature. The induced modifications in the polymer were analyzed by FTIR, UV-Vis spectroscopy, and XRD. In the FTIR spectra, the CF2 degradation accompanied by the formation of CF3 terminal and side groups were observed. In the UV-Vis spectra, the observed increase in the absorption at UV wavelengths is an indication of polymer carbonization. From XRD, the amorphization of the material was evidenced by the decrease in the intensity of the main diffraction peak. An exponential fit of the intensity of the IR absorption peaks resulted in the following values: 2.9 +/- 0.8; 4.5 +/- 0.9 and 5.6 +/- 0.8 nm for the latent track radius after irradiation with Xe, Au and U beams, respectively. (C) 2011 Elsevier B.V. All rights reserved.

Nd:YAG Laser Irradiation of Etched/Unetched Dentin Through an Uncured Two-step Etch-and-Rinse Adhesive and its Effect on Microtensile Bond Strength

Purpose: To evaluate whether Nd:YAG laser irradiation of etched and unetched dentin through an uncured adhesive affected the microtensile bond strength (pTBS). Materials and Methods: Flat dentin surfaces were created in 19 extracted human third molars. Adper Single Bond (SB) adhesive was applied over etched (groups 1 to 3) or unetched dentin (groups 4 to 6). The dentin was then irradiated with a Nd:YAG laser through the uncured adhesive, using 0.75 or 1 W power settings, except for the control groups (groups 1 and 4). The adhesive was light cured and composite crowns were built up. After 24 h, the teeth were sectioned into beams, with cross-sectional areas of 0.49 mm(2), and were stressed under tension. Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha = 5%). Dentin surfaces of fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM). Results: Acid etching, laser irradiation, and their interaction significantly affected bonding (p < 0.05). Laser irradiation did not improve bonding of etched dentin to resin (p > 0.05). However, higher pTBS means were found on unetched lased dentin (groups 5 and 6), but only in comparison to group 4, where neither lasing nor etching was performed. Groups 4 to 6 showed the lowest pTBS means among all groups tested (p < 0.05). Laser irradiation did not change the characteristics of the hybrid layers created, while solidification globules were observed on lased dentin surfaces under SEM. Conclusion: Laser irradiation of dentin through the uncured adhesive did not significantly improve the pTBS in comparison to the suggested manufacturer's technique.

Discovery and cross-section measurement of neutron-rich isotopes in the element range from neodymium to platinum with the FRS

Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of 60 <= Z <= 78. The new isotopes were unambiguously identified in reactions with a U-238 beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium. (C) 2012 Elsevier B.V. All rights reserved.

Effects of the particle sizes and concentrations on the X-ray absorption by CuO compounds

This work presents a study on the effects of the particle size, material concentration and radiation energy on the X-ray absorption. CuO nanoparticles and microparticles were incorporated separately into a polymeric resin in concentrations of 5%, 10% and 30% relative to the resin mass. X-ray absorption by these materials was analyzed with a CdTe detector. The X-ray absorption is higher for the nanostructured material compared to the microstructured one for low energy X-ray beams for all CuO concentrations. (c) 2011 Elsevier Ltd. All rights reserved.

An evaluation of dosimetric characteristics of MAGIC gel modified by adding formaldehyde (MAGIC-f)

Purpose: To evaluate the dosimetric characteristics of a new formulation of MAGIC gel, called MAGIC-f, which contains the addition of 3.3% formaldehyde, resulting in a gel with increased thermal stability. Methods: MAGIC-f gel was prepared and stored in hermetically sealed plastic containers. After irradiation, magnetic resonance images (MRI) were acquired to evaluate dose and dose distribution. Dosimetric characterization was performed by means of depth dose measurements, dose response sensitivity and linearity, temporal stability, energy and dose rate dependence, dose integration using sequential beams, temperature influence during MRI acquisition and dose distribution integrity. Results: MAGIC-f depth dose measurements are compatible with the dosimetric table data within +/- 4% uncertainty. The dosimeter's R-2 response varies linearly with dose at least from 0 to 6 Gy. The time-course of the sensitivity of the dosimeter following irradiation, indicated stabilization after 2 weeks. The dosimeter's response to irradiation was altered by 6% when increasing the energy from cobalt beams to 10 MV beams. The dose rate dependence of this new formulation of gel dosimeter is small: less than 2.5% for a variation from 200 to 500 cGy/min, and the dependence with the fractionation scheme is about 50% smaller than for standard MAGIC gel, The dependence on scanning temperature was also verified, and the integrity of the dose distribution was confirmed for a period of 90 days. Conclusions: The results demonstrate the applicability of this new dosimeter in tridimensional dose distribution measurements. (C) 2012 Elsevier Ltd. All rights reserved.

Experimental analyses of the poly(vinyl chloride) foams' mechanical anisotropic behavior

Assessing a full set of mechanical properties is a rather complicate task in the case of foams, especially if material models must be calibrated with these results. Many issues, for example anisotropy and heterogeneity, influence the mechanical behavior. This article shows through experimental analyses how the microstructure affects different experimental setups and it also quantifies the degree of anisotropy of a poly(vinyl chloride) foam. Monotonic and cyclic experimental tests were carried out using standard compression specimens and non-standard tensile specimens. Results are complemented and compared with the aid of a digital image correlation technique and scanning electron microscopy analyses. Mechanical properties (e.g., elastic and plastic Poisson's ratios) are evaluated for compression and tensile tests, for two different material directions (normal and in-plane). The material is found to be transversely isotropic. Differences in the results of the mechanical properties can be as high as 100%, or even more depending on the technique used and the loading direction. Also, the experimental analyses show how the material's microstructure behavior, like the evolution of the herein identified yield fronts and a spring back phenomenon, can influence the phenomenological response and the failure mechanisms as well as the hardening curves. POLYM. ENG. SCI., 52:2654-2663, 2012. (C) 2012 Society of Plastics Engineers

Loading a K-39 crossed optical dipole trap from a magneto-optical trap

In this work, we have applied sub-Doppler laser cooling to a K-39 magneto-optical trap in order to load a 1071 nm crossed optical dipole trap. The number of atoms loaded into the dipole trap was characterized as a function of the frequency and intensity of the cooling and repump laser beams. For the optimum conditions, the dipole trap has about 2 x 10(6) atoms at an atomic density of 2 x 10(12) cm(-3), with a temperature of about 10 mu K. This technique is a very simple procedure to load a K-39 optical dipole trap without a previous magnetic evaporative cooling step and may find application in other atomic physic systems.

Composite connections in slim-floor system: An experimental study

This paper reports the results of full-scale tests in beam-to-column connections for composite slim floor systems, including tests on Bare Steel connection and composite connection. The tested system consists of a concrete-filled composite column and a composite floor where an asymmetric steel beam is connected to a composite column by shear steel plates. Tests results previously obtained on partially encased composite beams were used to define the position of the headed studs in the slim floor system. Based on the obtained results of connections, the composite and Bare Steel connection behaved as semi-rigid and nominally pinned respectively. The tests results also indicated a significant contribution of the slim floor to the moment capacity of the connection. (C) 2011 Elsevier Ltd. All rights reserved.

Transverse pseudo-nonlinear effects measured in solid-state laser materials using a sensitive time-resolved technique

We present a detailed study of the Baryscan technique, a new efficient alternative to the widespread Z-scan technique which has been demonstrated [Opt. Lett. 36:8, 2011] to reach among the highest sensitivity levels. This method is based upon the measurement of optical nonlinearities by means of beam centroid displacements with a position sensitive detector and is able to deal with any kind of lensing effect. This technique is applied here to measure pump-induced electronic refractive index changes (population lens), which can be discriminated from parasitic thermal effects by using a time-resolved Baryscan experiment. This method is validated by evaluating the polarizability variation at the origin of the population lens observed in the reference Cr3+:GSGG laser material.

Optical parametric oscillation with distributed feedback in cold atoms

There is currently a strong interest in mirrorless lasing systems(1), in which the electromagnetic feedback is provided either by disorder (multiple scattering in the gain medium) or by order (multiple Bragg reflection). These mechanisms correspond, respectively, to random lasers(2) and photonic crystal lasers(3). The crossover regime between order and disorder, or correlated disorder, has also been investigated with some success(4-6). Here, we report one-dimensional photonic-crystal lasing (that is, distributed feedback lasing(7,8)) with a cold atom cloud that simultaneously provides both gain and feedback. The atoms are trapped in a one-dimensional lattice, producing a density modulation that creates a strong Bragg reflection with a small angle of incidence. Pumping the atoms with auxiliary beams induces four-wave mixing, which provides parametric gain. The combination of both ingredients generates a mirrorless parametric oscillation with a conical output emission, the apex angle of which is tunable with the lattice periodicity.

Portable light transmission measuring system for preserved corneas

Abstract Background The authors have developed a small portable device for the objective measurement of the transparency of corneas stored in preservative medium, for use by eye banks in evaluation prior to transplantation. Methods The optical system consists of a white light, lenses, and pinholes that collimate the white light beams and illuminate the cornea in its preservative medium, and an optical filter (400–700 nm) that selects the range of the wavelength of interest. A sensor detects the light that passes through the cornea, and the average corneal transparency is displayed. In order to obtain only the tissue transparency, an electronic circuit was built to detect a baseline input of the preservative medium prior to the measurement of corneal transparency. The operation of the system involves three steps: adjusting the "0 %" transmittance of the instrument, determining the "100 %" transmittance of the system, and finally measuring the transparency of the preserved cornea inside the storage medium. Results Fifty selected corneas were evaluated. Each cornea was submitted to three evaluation methods: subjective classification of transparency through a slit lamp, quantification of the transmittance of light using a corneal spectrophotometer previously developed, and measurement of transparency with the portable device. Conclusion By comparing the three methods and using the expertise of eye bank trained personnel, a table for quantifying corneal transparency with the new device has been developed. The correlation factor between the corneal spectrophotometer and the new device is 0,99813, leading to a system that is able to standardize transparency measurements of preserved corneas, which is currently done subjectively.

Emprego de ferramentas numéricas na avaliação do módulo de elasticidade em vigas roliças de madeira

Vigas são elementos estruturais encontrados na maioria das construções civis. Dentre os materiais de engenharia, destaca-se a madeira, por ter resistência mecânica satisfatória aliada a baixa densidade. A madeira roliça apresenta-se como boa solução na confecção de vigas, uma vez que não precisa ser processada, como é o caso da madeira serrada. O projeto de elementos estruturais de madeira requer o conhecimento de suas propriedades físicas e mecânicas, obtidas segundo as premissas de documentos normativos. Em se tratando da madeira roliça, os documentos normativos nacionais que tratam da determinação das propriedades de resistência e rigidez estão vigentes há mais de vinte anos sem revisão técnica. De forma geral, tanto as normas nacionais como as internacionais idealizam geometria troncocônica para as peças roliças de madeira, implicando equações simplificadas incapazes de prever a influência das irregularidades da forma na determinação do módulo de elasticidade longitudinal. Este trabalho objetiva avaliar a influência das irregularidades da geometria em peças roliças de madeira Corymbia citriodora e Pinus caribaea no cálculo do módulo de elasticidade longitudinal. Para tanto, utilizou-se do ensaio de flexão estática a três pontos, considerando também um modelo matemático simplificado, assumindo seção circular constante para a forma do elemento. As irregularidades das peças são consideradas nos modelos numéricos, constituídos de elementos finitos de barra e tridimensionais. Os resultados encontrados revelam equivalência estatística entre os módulos de elasticidade para ambas as formas de cálculo, indicando ser plausível a consideração de seção circular constante para as peças de madeira aqui avaliadas.

Tratamento alternativo para neuralgia pós-herpética após transplante pulmonar. Relato de caso

JUSTIFICATIVA E OBJETIVOS: A neuralgia pós-herpética (NPH) é a dor que permanece após o desaparecimento do episódio agudo de herpes zoster. O objetivo deste estudo foi relatar o tratamento da dor da NPH em paciente transplantado pulmonar. RELATO DO CASO: Paciente do sexo masculino, 73 anos, transplantado pulmonar há três anos, em uso de imunossupressores. Desenvolveu quadro de herpes zoster há um ano, com vesículas no oitavo espaço intercostal do hemitórax direito (HTD). O tratamento foi efetivo com ganciclovir; entretanto, o paciente evoluiu com dor em queimação, intensa, constante, com piora no último mês, com intensidade pela escala visual numérica (EVN) de 9, mesmo com uso de 600 mg/dia de gabapentina. Ao exame físico apresentava uma lesão avermelhada no HTD, hiperestésica. Foi instituído tratamento com gabapentina (900 mg), amitriptilina (25 mg), dipirona (8 g) e oxicodona (20 mg) ao dia. Feita a aplicação de laser de baixa intensidade (LBI) diariamente por uma semana, seguido de tratamento com amitriptilina tópica a 4%. A intensidade da dor diminuiu para 5. A frequência de aplicação do LBI diminuiu para uma vez a cada dois dias com melhora significativa com EVN entre 1 e 2. Teve alta hospitalar, com 25 mg/dia de amitriptilina oral e amitriptilina tópica a 4%. CONCLUSÃO: O uso do LBI e da amitriptilina tópica foi eficaz para remissão do quadro doloroso.

Reliability of buildings in service limit state for maximum horizontal displacements

Brazilian design code ABNT NBR6118:2003 - Design of Concrete Structures - Procedures - [1] proposes the use of simplified models for the consideration of non-linear material behavior in the evaluation of horizontal displacements in buildings. These models penalize stiffness of columns and beams, representing the effects of concrete cracking and avoiding costly physical non-linear analyses. The objectives of the present paper are to investigate the accuracy and uncertainty of these simplified models, as well as to evaluate the reliabilities of structures designed following ABNT NBR6118:2003[1&] in the service limit state for horizontal displacements. Model error statistics are obtained from 42 representative plane frames. The reliabilities of three typical (4, 8 and 12 floor) buildings are evaluated, using the simplified models and a rigorous, physical and geometrical non-linear analysis. Results show that the 70/70 (column/beam stiffness reduction) model is more accurate and less conservative than the 80/40 model. Results also show that ABNT NBR6118:2003 [1] design criteria for horizontal displacement limit states (masonry damage according to ACI 435.3R-68(1984) [10]) are conservative, and result in reliability indexes which are larger than those recommended in EUROCODE [2] for irreversible service limit states.

Contribution to assessing the stiffness reduction of structural elements in the global stability analysis of precast concrete multi-storey buildings

This study deals with the reduction of the stiffness in precast concrete structural elements of multi-storey buildings to analyze global stability. Having reviewed the technical literature, this paper present indications of stiffness reduction in different codes, standards, and recommendations and compare these to the values found in the present study. The structural model analyzed in this study was constructed with finite elements using ANSYS® software. Physical Non-Linearity (PNL) was considered in relation to the diagrams M x N x 1/r, and Geometric Non-Linearity (GNL) was calculated following the Newton-Raphson method. Using a typical precast concrete structure with multiple floors and a semi-rigid beam-to-column connection, expressions for a stiffness reduction coefficient are presented. The main conclusions of the study are as follows: the reduction coefficients obtained from the diagram M x N x 1/r differ from standards that use a simplified consideration of PNL; the stiffness reduction coefficient for columns in the arrangements analyzed were approximately 0.5 to 0.6; and the variation of values found for stiffness reduction coefficient in concrete beams, which were subjected to the effects of creep with linear coefficients from 0 to 3, ranged from 0.45 to 0.2 for positive bending moments and 0.3 to 0.2 for negative bending moments.