The effect of CO 2 laser irradiation on failed implant surfaces

The aim of this investigation was to evaluate the cleaning effect of CO 2 on surface topography and composition of failed dental implant surfaces. Ten failed dental implants were retrieved from nine patients (mean age, 46.33 �� 5.81 years) as a result of early or late failure. The implants were divided into two parts: one side of the implant was irradiated with a CO 2 laser (test side), while the other side did not receive irradiation (control side). The CO 2 laser was operated at 1.2 W in a continuous wave for 40 seconds (40 J energy). The handpiece of the CO 2 laser was kept at a distance of 30 mm from the implant surface, resulting in a spot area of 0.031415 cm 2 (38.20 W/cm 2; 1559 J/cm 2) in scanning mode (cervical-apical). One unused dental implant was used as a negative control for both groups. All implant surfaces were examined by scanning electron mi croscopy (SEM) and energy-dispersive spectrometer x-ray (EDS) for element analysis. SEM showed that the surface of the test sides consisted of different degrees of organic residues, appearing mainly as dark stains similar to those observed on the control sides. None of the test surfaces presented alterations such as crater-like alterations, lava-like layers, or melting compared with the nonirradiated surfaces. Foreign elements such as carbon, oxygen, sodium, calcium, and aluminum were detected on both sides. These results suggest that CO 2 laser irradiation does not modify the implant surface, although the cleaning effect was not satisfactory.

Investiga����o de Intrus��o de ��gua Salgada em Aq����fero Superficial a Partir de Medidas de Resistividade El��trica

A site investigation program was carried out to detect salt-water intrusions in a shallow sedimentary aquifer based on electrical resistivity measurements. The site is located close to Paranagu�� harbor, in the Paran�� State, Brasil. At this site, high chloride concentration contaminated shallow water wells used to supply water for local industries. The site investigation program included a fieldwork, dipole-dipole electrical profiling, resistivity piezocone tests, physical-chemical analysis of sampled water and interpretation of borehole logs. The resistivity piezocone tests provided two simultaneous information; the soil stratigraphy at a very detailed level and a quasi-continuous resistivity profile. Both information adequately complemented dipole-dipole electrical profiling test data. The integration of all test data allowed identifying the contaminated areas as well as guided the location of new water wells to be installed in this area.

Effects in the population inversion of3H4 level in Tm, Tm-Tb and Tm-Eu doped germanate glasses for amplifiers applications

The population inversion of the Tm3+ in GLKZ glass involved in the 1470 nm emission (3H4 ��� 3F 4) as a function of Tb (or Eu) concentration was calculated by computational simulation for a CW laser pumping at 792 nm. These calculations were performed using the experimental Tm���Tb an Tm���Eu transfer rates and the spectroscopic parameters of the Tm (0.1 mol %) system. The result shows that 0.2 mol % (Tb3+) and 0.4 mol % of Eu3+ ions propitiate best population inversion of Tm3+ (0.1 mol %) maximizing the amplification coefficient of germanate (GLKZ) glass when operating as laser intensity amplification at 1470 nm. Besides the effective deactivation of the 3F4 level, the presence of Tb3+ or Eu 3+ ions introduce a depopulation of the 3H4 emitting level by means of a cross relaxation process with Tm3+ ions. In spite of this, the whole effect is verified to be benefic for using Tm-doped GLKZ glass codoped with Tb3+ or Eu3+ as a suitable material for confectioning optical amplifiers that operates in the S-band for telecommunication.

Upconversion luminescence in Er3+ doped Ga10Ge 25S65 glass and glass-ceramic excited in the near-infrared

The infrared-to-visible frequency upconversion was investigated in Er 3+-doped Ga10Ge25S65 glass and in the transparent glass-ceramic obtained by heat-treatment of the glass above its glass-transition temperature. Continuous-wave and pulsed lasers operating at 980 nm and 1480 nm were used as excitation sources. The green (2H 11/2 ��� 4I15/2; 4S3/2 ��� 4I15/2) and red (4F9/2 ��� 4I15/2) photoluminescence (PL) signals due to the Er3+ ions were characterized. The PL decay times were influenced by energy transfer among Er3+ ions, by cross-relaxation processes and by energy transfer from the Er3+ ions to the host material. The PL from the Er3+ ions hosted in the crystalline phase was distinguished only when the glass-ceramic was excited by the 1480 nm pulsed laser. The excitation pathways responsible for the green and red PL bands are discussed to explain the differences between the spectra observed under continuous-wave and pulsed excitation. �� 2013 American Institute of Physics.

White light generation in Tm3+/Ho3+/Yb3+ doped PbO-GeO2 glasses excited at 980 nm

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Laser emission of a Nd-doped mixed tellurite and zinc oxide glass

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Investigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Investigation of chemical changes in sealers during application of the warm vertical compaction technique

Aim To assess (i) heat generated by pluggers during warm vertical compaction of gutta-percha and investigation of temperature changes on the external root surface during canal filling, and (ii) the chemical changes of root canal sealers induced by heat.Methodology Four sealers, namely AH Plus, MTA Plus and two other experimental sealers based on tricalcium silicate, were characterised. External temperatures generated on the root surface during warm vertical compaction of gutta-percha with different sealers inside the root canal were monitored using an infrared thermography camera. Chemical changes induced by heating the sealers were assessed by Fourier transform infrared (FT-IR) spectroscopy.Results MTA Plus and the experimental sealers were composed of a cement and radiopacifier, with epoxy resin or a water-soluble polymer as dispersant, whilst AH Plus was epoxy resin-based. The heat generated at the tips of the continuous wave pluggers was found to be lower than the temperature set and indicated on the device LCD display. The sealers reduced the heat generated on the external root surfaces during the heating phase. AH Plus sustained changes to its chemical structure after exposure to heat, whilst the other sealers were unaffected.Conclusions The temperatures recorded at the tips of continuous wave pluggers varied with their taper and were lower than the temperature set on the System B LCD display. Root canal sealers reduced the dissipation of heat generated during warm vertical compaction, with the temperature at the external root surface maintained at 37-41 degrees C, a temperature below that is necessary to cause irreversible damage to bone and periodontium. The use of AH Plus sealer during warm vertical compaction techniques results in chemical changes in the sealer. The effect on sealer properties needs to be further investigated.

Fast determination of beef quality parameters with time-domain nuclear magnetic resonance spectroscopy and chemometrics

The noteworthy of this study is to predict seven quality parameters for beef samples using time-domain nuclear magnetic resonance (TD-NMR) relaxometry data and multivariate models. Samples from 61 Bonsmara heifers were separated into five groups based on genetic (breeding composition) and feed system (grain and grass feed). Seven sample parameters were analyzed by reference methods; among them, three sensorial parameters, flavor, juiciness and tenderness and four physicochemical parameters, cooking loss, fat and moisture content and instrumental tenderness using Warner Bratzler shear force (WBSF). The raw beef samples of the same animals were analyzed by TD-NMR relaxometry using Carr-Purcell-Meiboom-Gill (CPMG) and Continuous Wave-Free Precession (CWFP) sequences. Regression models computed by partial least squares (PLS) chemometric technique using CPMG and CWFP data and the results of the classical analysis were constructed. The results allowed for the prediction of aforementioned seven properties. The predictive ability of the method was evaluated using the root mean square error (RMSE) for the calibration (RMSEC) and validation (RMSEP) data sets. The reference and predicted values showed no significant differences at a 95% confidence level.

High-throughput non-destructive nuclear magnetic resonance method to measure intramuscular fat content in beef

High intake of saturated fat from meats has been associated with cardiovascular disease, cancer, diabetes, and others diseases. In this paper, we are introducing a simple, high-throughput, and non-destructive low-resolution nuclear magnetic resonance method that has the potential to analyze the intramuscular fat content (IMF) in more than 1,000 beef portions per hour. The results can be used in nutritional fact labels, replacing the currently used average value. The method is based on longitudinal (T(1)) and transverse (T(2)) relaxation time information obtained by a continuous wave-free precession (CWFP) sequence. CWFP yields a higher correlation coefficient (r=0.9) than the conventional Carr-Purcell-Meiboom- Gill (CPMG) method (r=-0.25) for IMF in beef and is just as fast and a simpler pulse sequence than CPMG. The method can also be applied to other meat products.

Vibro-Acoustography Beam Formation with Reconfigurable Arrays

In this work, we present a numerical study of the use of reconfigurable arrays (RCA) for vibro-acoustography (VA) beam formation. A parametric study of the aperture selection, number of channels, number of elements, focal distance, and steering parameters is presented to show the feasibility and evaluate the performance of VA imaging based on RCA. The transducer aperture was based on two concentric arrays driven by two continuous-wave or toneburst signals at slightly different frequencies. The mathematical model considers a homogeneous, isotropic, inviscid medium. The point-spread function of the system is calculated based on angular spectrum methods using the Fresnel approximation for rectangular sources. Simulations considering arrays with 50 x 50 to 200 x 200 elements with number of channels varying in the range of 32 to 128 are evaluated to identify the best configuration for VA. Advantages of two-dimensional and RCA arrays and aspects related to clinical importance of the RCA implementation in VA, such as spatial resolution, image frame rate, and commercial machine implementation, are discussed. It is concluded that RCA transducers can produce spatial resolution similar to confocal transducers and steering is possible in the elevational and azimuthal planes. Optimal settings for number of elements, number of channels, maximum steering, and focal distance are suggested for VA clinical applications. Furthermore, an optimization for beam steering based on the channel assignment is proposed for balancing the contribution of the two waves in the steered focus.

Deconvolution of the EPR spectra of vanadium oxide nanotubes

In this work we report results of continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy of vanadium oxide nanotubes. The observed EPR spectra are composed of a weak well-resolved spectrum of isolated V4+ ions on top of an intense and broad structure-less line shape, attributed to spin-spin exchanged V4+ clusters. With the purpose to deconvolute the structured weak spectrum from the composed broad line, a new approach based on the Krylov basis diagonalization method (KBDM) is introduced. It is based on the discrimination between broad and sharp components with respect to a selectable threshold and can be executed with few adjustable parameters, without the need of a priori information on the shape and structure of the lines. This makes the method advantageous with respect to other procedures and suitable for fast and routine spectral analysis, which, in conjunction with simulation techniques based on the spin Hamiltonian parameters, can provide a full characterization of the EPR spectrum. Results demonstrate and characterize the coexistence of two V4+ species in the nanotubes and show good progress toward the goal of obtaining high fidelity deconvoluted spectra from complex signals with overlapping broader line shapes. (C) 2012 Elsevier Inc. All rights reserved.

Three time-based scale formulations for the two-stage lot sizing and scheduling in process industries

In this paper, we propose three novel mathematical models for the two-stage lot-sizing and scheduling problems present in many process industries. The problem shares a continuous or quasi-continuous production feature upstream and a discrete manufacturing feature downstream, which must be synchronized. Different time-based scale representations are discussed. The first formulation encompasses a discrete-time representation. The second one is a hybrid continuous-discrete model. The last formulation is based on a continuous-time model representation. Computational tests with state-of-the-art MIP solver show that the discrete-time representation provides better feasible solutions in short running time. On the other hand, the hybrid model achieves better solutions for longer computational times and was able to prove optimality more often. The continuous-type model is the most flexible of the three for incorporating additional operational requirements, at a cost of having the worst computational performance. Journal of the Operational Research Society (2012) 63, 1613-1630. doi:10.1057/jors.2011.159 published online 7 March 2012

Enhancement of the Nonlinear Optical Absorption of the E7 Liquid Crystal at the Nematic-Isotropic Transition

We present an experimental study of the nonlinear optical absorption of the eutectic mixture E7 at the nematic-isotropic phase transition by the Z-scan technique, under continuous-wave excitation at 532 nm. In the nematic region, the effective nonlinear optical coefficient beta, which vanishes in the isotropic phase, is negative for the extraordinary beam and positive for an ordinary beam. The parameter , whose definition in terms of the nonlinear absorption coefficient follows the definition of the optical-order parameter in terms of the linear dichroic ratio, behaves like an order parameter with critical exponent 0.22 +/- 0.05, in good agreement with the tricritical hypothesis for the nematic-isotropic transition.

Influence of prior 810-nm-diode intracanal laser irradiation on hydrophilic resin-based sealer obturation

Dentin wall structural changes caused by 810-nm-diode laser irradiation can influence the sealing ability of endodontic sealers. The objective of this study was to evaluate the apical leakage of AH Plus and RealSeal resin-based sealers with and without prior diode laser irradiation. Fifty-two single-rooted mandibular premolars were prepared and divided into 4 groups, according to the endodontic sealer used and the use or non-use of laser irradiation. The protocol for laser irradiation was 2.5W, continuous wave in scanning mode, with 4 exposures per tooth. After sample preparation, apical leakage of 50% ammoniacal silver nitrate impregnation was analyzed. When the teeth were not exposed to irradiation, the Real Seal sealer achieved the highest scores, showing the least leakage, with significant differences at the 5% level (Kruskal-Wallis test, p = 0.0004), compared with AH Plus. When the teeth were exposed to the 810-nm-diode laser irradiation, the sealing ability of AH Plus sealer was improved (p = 0282). In the Real Seal groups, the intracanal laser irradiation did not interfere with the leakage index, showing similar results in the GRS and GRSd groups (p = 0.1009).