The purpose of this in vitro study was to evaluate the effect of air-abrasion/zirconia sintering order on the yttria partially stabilized tetragonal zirconia polycrystal (Y-TZP) surface characterization (roughness, morphology, and phase transformation), flexural strength (FS), and shear bond strength (SBS) to a resin cement. Y-TZP specimens were air abraded with 50-μm Al2O3 particles after (AS), before (BS), or before and after zirconia sintering (BAS). For roughness (Ra), 30 block specimens (12×12×3.0 mm; n=10) had their surfaces analyzed by a profilometer. Next, on the air-abraded surfaces of these specimens, composite resin discs (n=30) were bonded with RelyX ARC. The bonded specimens were stored for 24 hours in distilled water at 37°C before shear testing. Failure mode was determined with a stereomicroscope (20×). The surface morphology (n=2) was evaluated by SEM (500×). For the four-point flexural strength test (EMIC DL2000), 39 bar-shaped specimens (20×4.0×1.2 mm; n=13) were air abraded according to the three conditions proposed, and an additional group (nonabraded) was evaluated (n=13). The quantitative analysis of phase transformation (n=1) was completed with Rietveld refinement with X-ray diffraction data. Ra (μm) and SBS (MPa) data were analyzed by one-way analysis of variance (ANOVA) and the Tukey test (α=0.05). Pearson correlation analysis was used to determine if there was a correlation between roughness and SBS. For FS (MPa) data, one-way ANOVA and the Dunnett C-test (α=0.05) were used. The air-abrasion/zirconia sintering order influenced significantly (p<0.001) Ra, SBS, and FS. The BS and AS groups presented the highest (1.3 μm) and the lowest (0.7 μm) Ra. The highest SBS (7.0 MPa) was exhibited by the BAS group, followed by the AS group (5.4 MPa) and finally by the BS group (2.6 MPa). All groups presented 100% adhesive failure. A weak correlation (r=-0.45, p<0.05) was found between roughness and SBS. The air-abrasion/zirconia sintering order provided differences in the surface morphology. The nonabraded (926.8 MPa) and BS (816.3 MPa) groups exhibited statistically similar FS values but lower values than the AS (1249.1 MPa) and BAS (1181.4 MPa) groups, with no significant difference between them. The nonabraded, AS, BS, and BAS groups exhibited, respectively, percentages of monoclinic phase of 0.0 wt%, 12.2 wt%, 0.0 wt%, and 8.6 wt%. The rougher surface provided by the air-abrasion before zirconia sintering may have impaired the bonding with the resin cement. The morphological patterns were consistent with the surface roughness. Considering the short-term SBS and FS, the BAS group exhibited the best performance. Air abrasion, regardless of its performance order, provides tetragonal to monoclinic transformation, while sintering tends to zero the monoclinic phase content.

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This study showed that CCC patients submitted to CRT have worse prognosis compared to patients with DCM and ICM who undergo CRT. Studies comparing CCC patients with and without CRT are warranted.

SummaryAn overview is presented of the analytical approaches developed by our research group over the last ten years for analysis of alternative fuel, both biomass and fossil. The alternative fuels are analyzed successively by PLC-8 (preparative liquid chrornatography-group-type) fractionation and high resolution gas chromatography. Some of the possibilities for fractionation and characterization of alternative fuels are herein exemplified with sugar cane bagasse pyrolysis products.

Background: Cardiac resynchronization therapy (CRT) is an established procedure for patients with heart failure (HF). However, trials evaluating its efficacy did not include patients with chronic Chagas cardiomyopathy (CCC), an important cause of HF in endemic countries. We aimed to assess the role of CRT in a cohort of patients with CCC. Methods: This was a retrospective study of consecutive CCC patients who underwent CRT between January 2005 and December 2012. We compared the outcomes of CCC patients who underwent CRT (CCC-CRT group) with those of ischemic and dilated cardiomyopathy patients who underwent CRT (CRT-control group) in the same period and with those of CCC patients with induced left bundle branch block (LBBB) who did not undergo CRT (CCC-control group). The primary endpoint was all-cause mortality and the secondary endpoint was echocardiographic changes, at least 24 months after CRT. Results: There were 115 patients in the CCC-CRT group, 311 in the CRT-control group, and 16 in the CCC-control group. The annual mortality rates were 25.4%, 10.9%, and 42.9%, respectively. Multivariate analysis adjusted for potential confounders showed that the CCC-CRT group had a two-fold (hazard ratio [HR] 2.11 [1.56-2.86], P<0.001) higher risk of death compared to the CRT-control group, and that the CCC-control group had an almost three-fold (HR 2.78 [1.09-7.01], P=0.032) higher risk of death compared to the CCC-CRT group. Conclusions: This cohort study showed that CRT has a favorable impact in patients with CCC, despite their worse prognosis compared to patients with other cardiomyopathies who undergo CRT.

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