EFFECTS OF SURFACE HYDRATION AND APPLICATION METHOD ON THE BOND STRENGTH OF SELF-ETCHING ADHESIVES TO DENTIN

The effect of application methods and dentin hydration on the bond strength of three self-etching adhesives (SEA) were evaluated; 195 extracted bovine incisors were used. The buccal surface was ground in order to expose the dentin, which remained 2-mm minimum thickness, measured by a thickness meter through an opening on the lingual surface. Adper Single Bond 2? was used for the control group. The SEA were applied following two modes of application: passive or active and two hydration states of the dentin surface—dry and wet. After light-curing, composite buildups were made using Grandio? composite. The specimens were sectioned and tested with a microtensile bond strength test. The application method and the hydration state resulted in statistical differences (p = 0.000) making the values of active application for μTBS to dentin higher than passive application. The wet surfaces showed higher μTBS to dentin ratios than dry surfaces. There were no statistical differences in μTBS among the SEA tested but there were differences regarding to control group.     

Structure and antioxidant activity of β-lactoglobulin-glycoconjugates obtained by high-intensity-ultrasound-induced Maillard reaction in aqueous model systems under neutral conditions

Sonication is a new processing technology in the dairy industry. The aim of this study was to test glycation of β-lactoglobulin (BLG) in Maillard reaction (MR) induced by high-intensity ultrasound in aqueous solution under neutral conditions at 10–15 °C, which is not favourable for the MR. BLG was sonicated in the presence of glucose, galactose, lactose, fructose, ribose and arabinose. Formation of Maillard reaction products (MRPs) was monitored by mass spectrometry, spectrophotometry and fluorimetry. Ultrasound treatment resulted in formation of MRPs with all tested carbohydrates. Ribose induced the highest degree of modification resulting in 76% of BLG modified and an average of three anhydroribose units attached. Circular dichroism spectra analyses indicated only minor alterations in secondary and tertiary structures. MRP obtained by ultrasound exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity and possessed increased iron-chelating activity and reducing power. High-intensity ultrasound efficiently promotes BLG-glycoconjugates formation by MR in aqueous solutions under non-denaturing conditions.     

Detection of ochratoxin A in tropical wine and grape juice from Brazil

BACKGROUND: Ochratoxin A (OTA) is the main mycotoxin found in grapes, wines and grape juices and is considered one of the most harmful contaminants to human health. In this study, samples of tropical wines and grape juices from different grape varieties grown in Brazil were analysed for their OTA content by high‐performance liquid chromatography. RESULTS: The detection and quantification limits for OTA were 0.01 and 0.03 µg L^?1 respectively. OTA was detected in 13 (38.24%) of the samples analysed, with concentrations ranging from < 0.03 to 0.62 µg L^?1. OTA was not detected in any of the grape juice samples. Most of the red wine samples proved to be contaminated with OTA (75%), while only one white wine sample was contaminated. However, the OTA levels detected in all samples were well below the maximum tolerable limit (2 µg L^?1) in wine and grape juice established by the European Community and Brazilian legislature. CONCLUSION: The results of this study indicate a low risk of exposure to OTA by consumption of tropical wines and grape juices from Brazil. © 2012 Society of Chemical Industry     

Chemical transformations of polymers. XVIII. Mercury-complexing polymers with pendent thiol groups. Preparation and medical uses

Poly(vinyltoluene-α-thiol) and poly(1-methacryloyloxyethane-2-thiol) were prepared by the polymeranalogous hydrolysis of the respective polymeric isothiuronium salts. The sorption of heavy metals from low-concentrated solutions was studied for both thiol polymers. Affinity increases in the series Pb < Ag < Hg in experiments in vitro. In vivo the mercury resorption in the gastrointestinal tract of rats was partly blocked by the methacrylate derivative if mercuric chloride or methylmercurichloride was administered (in the case of phenylmercurichloride the polymeric thiol was ineffective).     

Complex segregation analysis in a sample of consecutive newborns with cleft lip with or without cleft palate in Italy

The mode of inheritance of cleft lip with or without cleft palate (CL/P) has been extensively investigated, but the results are controversial. We report results of complex segregation analysis performed in the families of 636 consecutive newborns with CL/P registered in the northeast Italy and Emilia Romagna congenital malformation registries to test hypotheses regarding CL/P inheritance. The programs POINTER and COMDS have been used. POINTER could not distinguish between alternative genetic models, and only the hypothesis of no familial transmission could be rejected. COMDS results, after inclusion of the severity parameter, rejected the hypotheses of a single major locus and were consistent with the two-locus model with a major dominant locus and at least one modifier locus.     

MILD ELECTROLYTIC REDUCTION OF ASPHALTENES

Adsorption chromatography together with GPC have shown that the reduction of both bitumen and coal derived asphaltenes produces tower m.w. material with concurrent appearance of small amounts of higher m.w. components. The lower m.w. components could be separated into saturated and aromatic hydrocarbons and oxygenated material. In the case of coal derived asphaltenes some basic material could also be found. Polarography and cyclic voltaircnetry showed that oxidation/reduction processes occurred for the products of preparatively electroreduced asphaltenes but failed to identify the nature of the acceptors involved.     

The partition of N-dimensional space,using shells

In the field of pattern recognition there are problems where a decision can be made upon a set of training patterns. A training pattern represents a particular known case of the problem under investigation. Here it is represented as a point in the n-dimensional space Rⁿ, where each coordinate denotes a particular parameter of an observation or measurement. Each pattern point belongs to a single answer, which is the solution of this case. In this way, solved examples of the problem under investigation are represented by points of training patterns in the n-dimensional space. The question arises how to make the decision in order to find the answer for a given unknown pattern, i.e. a case without an answer, upon a set of training patterns used as basic knowledge.By the proposed method, shells are used to divide the n-dimensional space into regions where points of training patterns are located. Each shell has the shape of an n-dimensional rectangle and covers pattern points of the same answer. The partition of the n-dimensional space is achieved first in the adaptation phase, where a single shell belongs to the same answer as the pattern points it covers. The coverage of the space obtained after the adaptation phase is then improved in the following self-adaptation phase. Here, pairs of shells belonging to the same answer are merged into substitute shells. Thus, the number of shells is reduced without damage to the obtained quality of the coverage of the space Rⁿ. Upon such a coverage, a decision can be made for a given pattern by searching a shell which covers its pattern point. The answer belonging to this shell is also the answer for that pattern.The efficiency of this model has been satisfactorily demonstrated in two medical fields: prognosis of acute pancreatitis and in the diagnosis of disseminated cancer of unknown origin.     

A novel root locus calibrated in real gain in the inverses plane

The design of feedback control systems is presented by means of a novel root locus method in the plane of the inverse of the Laplace's variable. The steady-state error constants are unified in a generalized static gain and denominated real gain, which coincides with the gain coefficient used in the Bode, Nyquist, and Nichols methods. The design of compensators becomes easier and straightforward for both steady-state and transient performance. Some illusory effects occurring in the conventional s-plane design are discussed and eliminated     

Determination of Chromium Oxidation States in Part of the System CaO─3CaO · Cr2O3 in Air

The aim of the present work was to identify the structural characteristics of calcium chromium oxide formed at molar ratios CaO/Cr₂O₃≥ 3/1 and at elevated temperatures by the use of nondestructive techniques: instrumental neutron activation analysis (for determination of the total chromium content), electron paramagnetic resonance, magnetic susceptibility (for determination of chromium oxidation states), X-ray diffraction, and scanning electron microscopy. Our results suggest formation of the 3CaO · Cr₂O₅ compound, while at larger molar ratios only a small portion of Cr is incorporated into the crystalline CaO lattice as paramagnetic Cr³⁺.