A comparative in-vitro study of the bactericidal efficacy of sodium hypochlorite and chlorhexidine gluconate plus cetrimide on root canal anaerobic bacterial flora

INTRODUCTION: The permanence of necrotic tissues and/or bacteria may be responsible for persistent root canal infection. Root canal irrigation plays an important role in the success of endodontic treatment given that, on the one hand, it encourages the progressive elimination of the smear layer and, on the other, it neutralises microbic flora within the canal. The aim of this study was to test root canal irrigants from a microbiological point of view: sodium hypochlorite 5% (Niclor Ogna, Milan) and a new generation irrigant based on chlorhexidine gluconate and cetrimide (Cetrexidine VEBAS S. Giuliano Milanese-MI). METHODS: The experiments were performed on a series of obligatory anaerobic bacteria which are most frequently found in the endodontium, all belonging to the international collection "American Type Culture Collection" (ATCC) and supplied by Dasit SpA, Cornaredo (MI). The following bacterial strains were used in the experiment: Actinimyces odontolyticus ATCC 17929, Fusobacterium nucleatum ATCC 25586, Prevotella melanginogenica ATCC 25845, Porphyromonas gingivalis ATCC 33277. The working concentration (CFU/ml) was defined as 0.5 McFarland which corresponds to a concentration of microorganisms equivalent to approx. 1.5 x 10(3) bacteria. Each irrigant was kept in contact with the bacterial species used for this experiment for 10', 20', 30'. RESULTS: The results obtained confirm the bactericidal efficacy of both irrigants used, even after a short contact time. CONCLUSIONS: This does not mean that all irrigants are the same and/or promise the same results. This was a microbiological study, but in practice it is important to bear in mind other variables, such as contact time. Moreover, in order to increase the probability of endodontic treatment, root canal irrigants are also required to satisfy other criteria: biocompatibility, scarce toxicity, high proteolytic power.     

Standardized inspections of food premises during the 2004 Athens Olympic Games: descriptive analysis and risk factors for unsatisfactory results

Standardized inspections of food premises are part of environmental health systems implemented worldwide. The food safety strategy for the 2004 Olympic Games included standardized inspections to ensure uniformity and consistency of procedures and effective electronic management of data. Inspections were carried out by 196 inspectors in the five Olympic cities: Athens, Thessalonica, Volos, Iraklio, and Patra. From January 2003 to September 2004, a total of 1,249 food premises were inspected. An unsatisfactory inspection result (C grade) was received by 347 (27.8%) food premises, a relatively satisfactory result (B grade) was received by 332 (26.6%), and a satisfactory result (A grade) was received by 570 (45.6%). About 16% of inspected premises did not hold a valid permit. Unsatisfactory inspection results were more frequent for premises located in the two largest Greek cities in comparison with the other smaller cities (relative risk = 1.95, 95% confidence interval [CI] = 1.36 to 2.80). Based on logistic regression analysis, unsatisfactory inspection results were positively associated with food premises that were not located on a ground floor (odds ratio [OR] = 2.56, 95% CI = 1.39 to 4.73) and negatively associated with application of hazard analysis critical control point (HACCP) principles (OR = 0.27, 95% CI = 0.10 to 0.71). Food hygiene education through formal training programs should be encouraged to improve compliance of food premises. Food premises located on hotel floors and serving buffet meals are at higher risk for unsatisfactory conditions. Businesses that implemented a HACCP system within their operations to ensure food safety operated under more hygienic conditions. Future inspections by Public Health Authorities should involve elements of audit after the legislation for the application of HACCP principles.     

Comparative study of copper electrodeposition from sulphate acidic electrolytes in the presence of IT-85 and of its components

The effect of a new additive (IT-85) representing a mixture of triethyl-benzyl-ammonium chloride (TEBA) and hydroxyethylated-2-butyne-l,4-diol (Ferasine) on the kinetics of copper electrodeposition from sulphate acidic electrolytes, as well as on the morphology and structure of copper deposits was investigated and compared with those exerted by its two components, TEBA and Ferasine. Quasi-steady state hydrodynamic voltammetry at a rotating-disc electrode and electrochemical impedance spectroscopy were performed in order to obtain information about the kinetics of the cathodic process. SEM and X-ray diffraction analysis were used to examine the morphology and the structure of copper deposits. The kinetic parameters (_c, k₀) obtained by both Tafel and Koutecky-Levich interpretations showed that all tested organic additives have an inhibiting effect on copper electrodeposition. Unlike IT-85 or Ferasine, TEBA acts only as a blocking agent in the copper discharge process, without changing the reaction pathway corresponding to the absence of additives. Comparison of the inhibiting effects exerted by IT-85 and its components on the electrodeposition process pointed to the existence of a beneficial complementarity of TEBA and Ferasine when they are used in mixture.     

Some properties of highly refractory ceramics in the system MgO-MgAl2O4

Conclusions A region for compositions in the system MgO-MgAl₂O₄was detected which has great interest for practical use.Compositions containing up to 15% Al₂O₃ permit a big improvement to be obtained in the spalling resistance of periclase ceramics with a simultaneous reduction in the sintering temperature.Spinel and compositions close to it are distinguished from periclase by a lower volatilization capacity. This makes it possible to use the corresponding ceramic materials at temperatures that are much higher than with the ceramics containing a predominant content of periclase, despite the fact that in terms of deformation the spinel is much inferior to the periclase. The limiting service temperature of periclase ceramics (especially in vacuum) is limited not by the thermomechanical and refractory properties but by the high volatilization of the magnesia.It should be mentioned that there is a reduction in the sintering temperature and that bodies close in composition to spinel have high strengths.Bodies of intermediate composition containing from 20 to 50% Al₂O₃ apparently are of no practical interest as highly refractory ceramics.     

Efficient PCA-driven EAs and metamodel-assisted EAs,with applications in turbomachinery

This article presents methods to enhance the efficiency of Evolutionary Algorithms (EAs), particularly those assisted by surrogate evaluation models or metamodels. The gain in efficiency becomes important in applications related to industrial optimization problems with a great number of design variables. The development is based on the principal components analysis of the elite members of the evolving EA population, the outcome of which is used to guide the application of evolution operators and/or train dependable metamodels/artificial neural networks by reducing the number of sensory units. Regarding the latter, the metamodels are trained with less computing cost and yield more relevant objective function predictions. The proposed methods are applied to constrained, single- and two-objective optimization of thermal and hydraulic turbomachines.     

Improving Management Efficiency at Aerospace Enterprises

Russian Engineering Research - The adoption of an integrated management system, based on a systemic approach to production and management problems, improves management efficiency at an enterprise....