Plasma-polymerized acetylene nanofilms modified by nitrogen ion implantation

Thin films were prepared by plasma enhanced chemical vapour deposition (PECVD) from a mixture of acetylene and argon, and post deposition-treated by plasma immersion ion implantation (PIII). The effect of PIII on the nanofilms properties was evaluated as a function of treatment time. The average thickness and roughness were diminished upon PIII. On the other hand, hardness (0.7-3.9 GPa) and elastic modulus (29-54 GPa) increased upon 60 min of ion bombardment. Such results are ascribed mainly to the densification of the film structure caused by the increment in the crosslinking degree with increasing the energy deposited in the films. Wettability of the samples, investigated by contact angle measurements, was reduced (from 64 to 21°) right after PIII. This result, attributed to the introduction of polar groups in the film structure, was not preserved as the sample was aged in atmosphere. After aging, contact angles were larger than 70° but still smaller than 90°. Although the wettability has decreased with aging, the hydrophilic character of the samples was preserved. For certain treatment times, nitrogen PIII turned the plasma-polymerized acetylene films smoother, denser, mechanically and tribologicaly more resistant than the as-deposited material. © 2013 Elsevier B.V.

Determination of Glycerol in Biodiesel Using a Nickel(II) Oxyhydroxide Chemically Modified Electrode by Cyclic Voltammetry

A glassy carbon electrode chemically modified with nickel oxyhydroxide from a nickel hexacyanoferrate (NiHCF) film was used to determine glycerol in biodiesel by cyclic voltammetry. The modified electrode exhibited a linear response to glycerol concentration in the range from 0.05 to 0.35mmol L-1, and a detection limit of 0.030mmol L-1. The glycerol concentration found in the biodiesel sample was 0.156mmol L-1. The method developed in this study showed a recovery of (100.3±5.0)%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vestibuloplasty by modified kazanjian technique in treatment with dental implants

Dentists are often faced with extensively resorbed mandibular ridges with shallow buccal vestibule and high insertion of the mentalis muscle in relation to the crest of the ridge, causing the displacement of the prosthesis. Vestibuloplasty techniques aim at eliminating the muscle insertions, reposition the mucosa, and increase the area chapeável, giving more stability to the prosthesis. Among the techniques to deepen the vestibule are submucosal vestibuloplasties by secondary epithelialization and with mucosal and skin grafts. We will discuss vestibuloplasty by secondary epithelialization with emphasis on the so-called modified Kazanjian technique. This technique provides an appropriate result and does not require hospitalization, additional surgery at the donor, or prolonged periods without the use of prosthesis. © 2013 by Mutaz B. Habal, MD.

Structural characteristics of P123-modified supercritical drying and hydrophobic ambient pressure drying aerogels

Supercritical drying (SCD) and hydrophobic ambient pressure drying (APD) aerogels were prepared from hydrolysis of tetraethoxysilane in solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (P123) in the range of composition below the threshold for the ordered mesoporous silica precipitation. APD was carried out after silylation of wet gels with trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDZ). The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. Wet gels are formed by mass-fractal domains, with fractal dimension close to 2, and larger pores superposing the pores belonging to the fractal structure in case of high P123 concentrations. Aerogels exhibit smaller-sized mass-fractal domains with larger mass-fractal dimension accounting for some porosity elimination on drying. The pore volume of the aerogels increases significantly with the P123 amount and it is even larger in the APD aerogels than in the SCD aerogels. © 2013 Elsevier B.V. All rights reserved.

Dynamics characterization of modified Gross-Pitaevskii equation

The dynamics of dissipative and coherent N-body systems, such as a Bose-Einstein condensate, which can be described by an extended Gross-Pitaevskii formalism, is investigated. In order to analyze chaotic and unstable regimes, two approaches are considered: a metric one, based on calculations of Lyapunov exponents, and an algorithmic one, based on the Lempel-Ziv criterion. The consistency of both approaches is established, with the Lempel-Ziv algorithmic found as an efficient complementary approach to the metric one for the fast characterization of dynamical behaviors obtained from finite sequences. © 2013 Elsevier B.V. All rights reserved.

Determination of copper in different ethanolic matrices using a chloropropyl silica gel modified with a nanostructured cubic octa(3-aminopropyl)octasilsesquioxane

The chloropropyl silica gel was modified with octa(3-aminopropyl) octasilsesquioxane and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), spectroscopies, and surface and area porosity. The specific sorption capacity of metallic ions (Cu2+ and Ni2+) increases in the following solvent order: water < ethanol 42% < ethanol < ketone. The high values of the constant (K) in the order of 103 L mol-1 suggested the high adsorbent capacity of the modified silica (SGAPC) for Cu2+ and Ni2+. SGAPC was applied to a separation column and shows recoveries of around 100% of copper in samples of sugar cane spirit, vodka, ginger brandy, and ethanol fuel. © 2013 Devaney Ribeiro Do Carmo et al.

Environmental ageing studies of chemically modified micro and nanofibril phenol formaldehyde composites

Cellulose micro and nano fibrils were extracted from banana macro fibres and chemically modified using sodium hydroxide, formic acid, 3-methacryloxy propyltrimethoxy silane. These untreated and chemically treated fibrils were incorporated into PF resin and the specimens were prepared. The composites were subjected to long-term water ageing, thermal ageing soil burial and outdoor weathering. The mechanical properties are reduced under all ageing conditions. The present study investigates the effects of different types of ageing on macro fibre, microfibril and nanofibril reinforced PF composites. The effect of chemical modifications of fibres on the degradability of the composites at different environments also has been analysed. © 2013 Elsevier B.V.

Commercially pure titanium implants with surfaces modified by laser beam with and without chemical deposition of apatite. Biomechanical and topographical analysis in rabbits

Objectives: The purpose of this study was to evaluate the surfaces of commercially pure titanium (cp Ti) implants modified by laser beam (LS), without and with hydroxyapatite deposition by the biomimetic method (HAB), without (HAB) and with thermal treatment (HABT), and compare them with implants with surfaces modified by acid treatment (AS) and with machined surfaces (MS), employing topographical and biomechanics analysis. Methods: Forty-five rabbits received 75 implants. After 30, 60, and 90 days, the implants were removed by reverse torque and the surfaces were topographically analyzed. Results: At 30 days, statistically significant difference (P < 0.05) was observed among all the surfaces and the MS, between HAB/HABT and AS and between HAB and LS. At 60 days, the reverse torque of LS, HAB, HABT, and AS differed significantly from MS. At 90 days, difference was observed between HAB and MS. The microtopographic analysis revealed statistical difference between the roughness of LS, HAB, and HABT when compared with AS and MS. Conclusions: It was concluded that the implants LS, HAB, and HABT presented physicochemical and topographical properties superior to those of AS and MS and favored the osseointegration process in the shorter periods. In addition, HAB showed the best results when compared with other surfaces. © 2012 John Wiley & Sons A/S.

Five-year follow-up of modified implant-supported overdenture in an iliac crest autograft failure: Clinical report

The treatment of extensive pathologic lesions in the jaw, most of the time, can generate rehabilitation problems to the patient. The solid ameloblastoma is a locally invasive odontogenic tumor with a high recurrence rate. Its treatment is aggressive and accomplished through resection with safety margin. The criterion standard for reconstruction is autogenous bone, but it can provide a high degree of resorption, causing inconvenience to the patient because of lack of rehabilitative option. This study aimed to describe a patient with ameloblastoma treated through resection and reconstruction with autogenous bone graft, in which, after an extensive resorption of the graft was made, a modified bar was applied to support a prosthetic implant overdenture. Copyright © 2013 by Mutaz B. Habal, MD.

Randomized controlled clinical trial evaluating connective tissue graft plus resin-modified glass ionomer restoration for the treatment of gingival recession associated with non-carious cervical lesion: 2-year follow-up

Background: The aim of this clinical study is to evaluate the 2-year term results of gingival recession (GR) associated with non-carious cervical lesions (NCCLs) treated by connective tissue graft (CTG) alone or in combination with a resin-modified glass ionomer restoration (CTG+R). Methods: Thirty-six patients with Miller Class I buccal GR associated with NCCLs completed the follow-up. The defects were randomly assigned to receive either CTG or CTG+R. Bleeding on probing (BOP), probing depth (PD), relative GR, clinical attachment level (CAL), and cervical lesion height coverage were measured at baseline, 6 months, 1 year, and 2 years after treatment. Results: Both groups showed statistically significant gains in CAL and soft-tissue coverage. The differences between groups were not statistically significant in BOP, PD, relative GR, or CAL after 2 years. Cervical lesion height coverage was 79.31% ± 18.51% for CTG and 71.95% ± 13.25% for CTG+R (P >0.05). Estimated root coverage was 91.56% ± 11.74% for CTG and 93.29% ± 7.97% for CTG+R (P ≥0.05). Conclusions: Within the limits of the present study, it can be concluded that both procedures provide comparable soft tissue coverage after 2 years of follow-up.