Kriging metamodel management in the design optimization of a CNG injection system

This paper deals with the use of Kriging metamodels in multi-objective engineering design optimization. The metamodel management issue to find the tradeoff between accuracy and efficiency is addressed. A comparative analysis of different strategies is conducted for a case study devoted to the design of a component of the injection system for Compressed Natural Gas (CNG) engines. The computational results are reported and analyzed for a performance assessment conducted with a data envelopment analysis approach.     

A Merit Function for Variational Inequalities Applied to Equilibrium Problems

In this note, we introduce a new continuously differentiable merit functionfor solving variational inequalities. Our function is closely related to theaugmented lagrangian function for nonlinear optimization problems. We solvetwo equilibrium problems and obtain numerical results making use of aquasi-Newton method. Our computational experience shows that the new functionperforms quite well.     

Copper adaptation and methylotrophic metabolism in Candida boidinii

The importance of the antioxidant enzyme superoxide dismutase (CuZnSOD) in the metabolic switch from normotrophic to methylotrophic conditions was studied in the facultative methylotrophic yeast Candida boidinii. Copper adaptation was performed to qualify C. boidinii as a suitable cellular system to study the effect of induction of CuZnSOD, and other biochemical components along the copper detoxification system, on methanol adaptation. Copper adaptation results in the induction of CuZnSOD peroxidase activity as well as of glutathione. The effects at the metabolic level of exposure to both copper and methanol were also studied: the results suggest that the effect on antioxidant enzyme levels as a function of the change of trophic condition are predominant with respect to the effects of copper administration. Thus, the methanol-dependent induction of such enzymes is likely to provide a sufficient protection for the cells against toxic effects depending on copper administration. Administration of copper under methylotrophic conditions decreases the growth rate in spite of the high levels of antioxidant enzymes that are elicited by copper treatment. The adaptation to methanol metabolism was studied alsoafter methanol-independent induction of CuZnSOD, glutathione and catalase levels, obtained by exposure to high copper concentrations in glucose-containing medium. The metabolic changes induced by copper are persistent over several re-inoculations in normo-cupric glucose medium, thus allowing the study of the glucose-to-methanol switch on cells exhibiting high levels of antioxidant enzyme activities. Under such conditions the lag time observed during the transition from normotrophic to methylotrophic conditions is strongly reduced.     

Acoustic Emission Damage Assessment of Steel/CFRP Bonds for Rehabilitation

The use of adhesively bonded carbon fiber reinforced polymer (CFRP) laminates is increasingly being considered for the rehabilitation of metallic structures. The effective structural monitoring of steel/CFRP adhesive joints is of critical importance to assess the design service performance of the system, which ultimately depends on the bond damage tolerance at the load transfer regions. In the present study laboratory static and fatigue tests were conducted on steel/CFRP skin doubler and double strap joint specimens, which were monitored using the acoustic emission (AE) technique. The characteristics of the AE signals were correlated with the mechanical response of the samples, in order to understand the AE response associated with the accumulation of bond damage. One-dimensional source location was also performed to examine the initiation and the development of the disbond. The results show that AE parameter-based analysis is an effective nondestructive evaluation tool for bond damage detection and area location.     

Preparation and optical characterization of photosensitive multilayered structures based on polythiophenes and tetracyanoquinodimethane

Organic double layers obtained by electrodeposition of a substituted polythiophene followed by spin-coating of a Tetracyanoquinodimethane (TCNQ) electron acceptor layer, are characterized by means of spectrophotometric measurements carried out in the UV-VIS-IR range. According to the optical data, the electron acceptor molecules reduce to the singly ionized state as a consequence of a charge-transfer reaction that takes place at the interface with the electrodeposited polymer, which acts as an electron donor. Rectifying heterojunctions are obtained by depositing the double layers on the top of monocrystalline silicon wafers, and on the top of monocrystalline silicon wafers coated with electrochemically de-doped poly(3,4-ethylendioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS). Current versus voltage measurements performed in the dark and under halogen light irradiation show that the developed heterojunctions exhibit photosensitive charge transport features, promising in view of photovoltaic applications.     

A multi-institutional study confirms the presence and expression of simian virus 40 in human malignant mesotheliomas

Exposure to the carcinogen asbestos is a major factor in the development of malignant mesothelioma. However, not all mesotheliomas are associated with asbestos exposure, and only a small minority of people exposed to asbestos develop mesothelioma. Therefore, the identification of the cofactors that render certain individuals more susceptible to asbestos or that cause mesothelioma in people not exposed to asbestos has been a major priority of the International Mesothelioma Interest Group. The possible association of SV40 with mesothelioma was recently discussed in a special session at the Fourth International Mesothelioma Interest Group Conference, and it was decided to conduct a multi-institutional study to independently verify the presence of this tumor virus in mesotheliomas. We report the results of this investigation: (a) DNA and protein analyses revealed SV40 sequences and SV40 large T antigen expression in 10 of 12 mesotheliomas tested (83%); and (b) electron microscopy demonstrated variable amounts of asbestos fibers in 5 (71%) of 7 corresponding lung tissues available for analysis. Our results demonstrate that SV40 DNA is frequently present and expressed in mesotheliomas in the United States. Because our data demonstrate that some patients test positive for both SV40 and asbestos, the possibility that these two carcinogens interact should be investigated in future studies.