Influence of Preaging Treatment on Bake-Hardening Response and Electrochemical Corrosion Behavior of High Strength Al-Zn-Mg-Cu-Zr Alloy

The influence of preaging (PA) treatments on the bake hardening (BH) response of a AlZnMgCuZr aluminum alloy which served as automotive body structures were studied in this paper. A novel two-step PA treatment was particularly designed and further employed. The mechanical properties of the alloy were tested in detail. The microstructure was characterized by optical microscope (OM), transmission electron microscopy (TEM) and 3D measuring laser microscope (3D–MLM). Meanwhile, the corrosion behavior was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results indicated that the PA treatment was beneficial for the improvement of BH response after baking at 180 °C immediately after the solution treatment and the micro-hardness reached the peak value (194 HV) after 10 h holding, which had a percentage improvement of 110.87% compared to the hardness under the solution condition. The PA treatments decreased natural aging (NA) adverse effects, while it had the lowest NA effect and optimal BH response under 120 °C/20 min. Such a novel two-step PA treatment was revealed further to decrease the NA effect and increase the BH response compared to the optimal PA treatment, in particular, the BH value could reach 168 MPa and was 21.7% higher than that of optimal PA + NA treatment. The optimal corrosion resistance has been shown up by the combined characterizations of potentiodynamic polarization curves, EIS Nyquist plots, and 3D–MLM images.

Pro-innovation restructuring strategy: case study of a multipurpose public organization in health

The aim of this article is to measure the effect on performance, of the innovation in the organizational structure of the laboratories for clinical research associated with healthcare in infectious diseases of the Evandro Chagas National Institute of Infectious Diseases (INI) at Fiocruz in 2007, na effect herein identified as representative of the corporate intangible assets resulting from such restructuring strategy. The method consists, first, in the analysis of the literature about the measurement of intangible assets and organizational innovation, the potential effects of organization�s structure in performance, and the assessment of multipurpose public organizations in health, as sources of the basic notion on relations between intangible assets, organizational structure and performance which is used in this research. Next, the empirical research involves: (a) characterizing the change in organizational structure of 8 INI laboratories; (b) quantifying variables on the use of consumer goods and specialized personnel and on the production of teaching, research and health care; (c) calculating indicators about the development of relative technical efficiency of INI laboratories in the period 2002-2014, through Data Envelopment Analysis (DEA); and (d) using these indicators to compare the performance of these laboratories before and after the organizational innovation associated with the adoption of the Innovative Structure in their restructuring. As a contribution to knowledge, opens up prospects of collaborative research in Administration, Accounting and Economics for the development of a metric for organizational innovation. As management contribution, confirms the association between restructuring of INI laboratories as Innovative Organizations and their improvement in performance. Although the case study method imposes limitations to the generalizability of these results, mainly because there are no sufficient multipurpose organizations that use this methodology in performance assessment, it brings evidence on the potential benefit of the entrepreneurial-oriented innovation for the expansion and improvement of multipurpose public organizations.

Mathematical model indicates nonlinearity of noradrenaline effect on rat renal artery

The aim of this work is to present the efficacy of a previously introduced computational procedure, developed for evaluation of vascular responsiveness. On this reason, as an example a common study of noradrenaline (NA) effect on a rat renal artery under in vitro conditions was arbitrarily selected. The response of the arterial segment to NA doses (0.1-10 μg) was digitally recorded on a PC and employed to develop mathematical model of NA effect. Using the model, the following NA effect variables were determined: the vessel sensitivity parameter, mean effect time and rate constant, respectively, characterizing the effect intensity, duration, and regression and also classic response variables: the maximal effect and time of the maximal effect. The two-way analysis of variance followed by Bonferroni’s test revealed a significant influence of the increasing NA dose on the vessel sensitivity parameter and mean effect time. These findings indicated nonlinearity of processes underlying NA effect on the rat renal artery over the given range of NA doses. The procedure exemplified has the potential for use as an effective adjunct to routine studies of vascular responsiveness as it enables the extraction of meaningful information which cannot by obtained by common manual evaluation procedures.

Sodium-proton exchange stimulates Ca2+ release from acidocalcisomes of Trypanosoma brucei

Acidocalcisomes are acidic vacuoles present in trypanosomatids that contain a considerable fraction of intracellular Ca2+ [Vercesi, Moreno and Docampo (1994) Biochem. J. 304, 227–233; Scott, Moreno and Docampo (1995) Biochem. J. 310, 789–794; Docampo, Scott, Vercesi and Moreno (1995) Biochem. J. 310, 1005–1012]. The data presented here indicate that Na+ stimulates Ca2+ release from the acidocalcisomes of digitonin-permeabilized Trypanosoma brucei procyclic trypomastigotes in a dose-dependent fashion, this effect being enhanced by increasing pH of the medium from 7.0 to 7.8. The hypothesis that this Na+ effect was mediated by alkalinization of the acidocalcisomes via a Na+/H+ antiporter was supported by experiments showing that Na+ promotes release of Acridine Orange previously accumulated in these vacuoles. This putative antiporter did not transport Li+ and was not sensitive to the amiloride analogue 5-(N-ethyl-N-isopropyl)amiloride. Addition of the Na+/H+ ionophore monensin to intact cells loaded with fura 2, in the nominal absence of extracellular Ca2+ to preclude Ca2+ entry, was followed by an increase in cytosolic Ca2+ concentration ([Ca2+]i), which was more accentuated in the presence of extracellular Na+. An increase in intracellular pH (pHi) of BCECF-loaded cells was detected after addition of monensin in the presence of extracellular Na+, whereas a dramatic decrease in pHi was detected in its absence, thus indicating the presence of a significant amount of releasable protons in the acidic compartments. These results are consistent with the presence of a Na+/H+ antiporter in the acidocalcisomes that could be involved in the regulation of pHi and [Ca2+]i in these parasites.

Effects of sodium and proton pump activity on respiratory burst and pH regulation of rat alveolar macrophages

At pH 7.4, extracellular Na+ removal inhibited the rat alveolar macrophage respiratory burst (RB) stimulated by phorbol 12-myristate 13-acetate (PMA) or zymosan-activated serum (ZAS). At pH 6.8, the RB was lower and decreased the Na+ effect. Amiloride inhibited the ZAS RB independently of effects on Na(+)-H+ exchange, but did not affect PMA stimulation. NBD-Cl, an H(+)-ATPase inhibitor, significantly inhibited the PMA or ZAS RB. Na+ removal caused sustained elevation of intracellular free [Ca2+], which previous studies suggested inhibits the RB. Intracellular pH (pHi) was lower at pHo 6.8 compared with pHo 7.4, but not altered by Na+ removal. PMA stimulation resulted in acidification corresponding with onset of superoxide production. At pHo 7.4, recovery to baseline pHi occurred that was not inhibited by amiloride or Na+ removal. In contrast, amiloride slowed pHi recovery after an exogenous acid load. Addition of H(+)-ATPase inhibitors, NBD-Cl or bafilomycin, following PMA stimulation or acid loading, inhibited pHi restoration. These studies suggest that pHi regulation following stimulation was mainly through a proton pump, whereas Na(+)-H+ exchange occurred only after greater acid loading. Nevertheless, Na+ and pH interacted to modulate the RB independent of Na(+)-H+ exchange.