High Chromium Cast Irons: Destabilized-Subcritical Secondary Carbide Precipitation and Its Effect on Hardness and Wear Properties

This work evaluates the effect of a destabilization treatment combined with a subcritical diffusion (SCD) and a subsequent quenching (Q) steps on precipitation of secondary carbides and their influence on the wear properties of HCCI (16%Cr). The destabilization of the austenite at high temperature leads to a final microstructure composed of eutectic and secondary carbides, with an M₇C₃ nature, embedded in a martensitic matrix. An improved wear resistance was observed in the SCD?+?Q samples in comparison with the Q one, which was attributed to the size of secondary carbides.     

Effects of Microwave-Assisted Hot Air Drying and Conventional Hot Air Drying on the Drying Kinetics,Color, Rehydration,and Volatiles of Moringa oleifera

In this study, the fresh Moringa oleifera pods (Drumsticks) were dehydrated by microwave-assisted hot air drying (MAHD) and conventional hot air drying methods. The samples were dried at three different temperatures, viz. 50, 60, and 70°C, with and without the application of microwaves. Microwave power density of 1 W/g was used for the MAHD. The final moisture content was targeted as 13% wb. The drying curves and drying rate curves were plotted and compared. The kinetics of drying obtained experimentally were correlated with the Page equation. The constants K and N of the Page equation were determined to predict the drying kinetics for varying conditions. The quality attributes, namely, color, rehydration ratio, and volatile compounds, were analyzed and compared with that of the fresh Moringa pods. The volatile compounds were analyzed using z-Nose (an electronic nose; Electronic Sensor Technology, Newbury Park, CA) and bioactive molecules were analyzed using gas chromatography–mass spectrometry. The results showed that the MAHD method had significantly (P < 0.05) reduced the loss of volatiles during drying. Also, MAHD preserved most of the bioactive molecules when compared to the conventional hot air drying method. The samples dried at 50°C using MAHD were the best in terms of all of the quality attributes tested in this study. Also, the results established that the z-Nose can be used as a quick and inexpensive means to assess the effect of different process parameters on the aromatic quality of the product and quantitatively classify quality based on aroma.     

Growth and aggression: I. Childhood to early adolescence.

Followed 4th-grade subjects (116 girls and 104 boys) in annual assessments of aggressive patterns over 6 years, from childhood through early adolescence. Results indicated that (a) there were marked normative shifts from childhood to adolescence in the nature of aggressive themes in conflicts, with developmental persistence of direct confrontation and physical attacks (i.e., a "brutality norm") in male–male conflicts and an increase in social aggression and ostracism in female–female conflicts; (b) individual differences in teacher ratings (and in self-ratings) of aggressive patterns were reasonably continuous over 6 years, with a decay in magnitude as the interval between measurements increased; and (c) there were developmental shifts in the factor structure of aggressive measures, along with changes in how measures from the "self" and "others" were aligned. Some theoretical implications for development, continuity, and convergence are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diffusion of drugs from hydrogels and liposomes as drug carriers

BACKGROUND: The mass transfer of model drugs Lidocaine hydrochloride and Dihydroquercetin from hydrogels (the usual carriers for topical drugs), and hydrogels containing liposomes, as novel drug vehicles, was studied. Diffusion experiments were performed using a Franz diffusion cell. Experimental data were used to calculate drug diffusion coefficients across membranes, and their effective diffusion coefficients from hydrogels and liposome containing hydrogels. For the first time the diffusion resistance of all drug carriers was determined from corresponding diffusion coefficients. The main aim of this work was the study of drug diffusion coefficients from liposomes and their comparison with related diffusion coefficients from hydrogels to find how liposomes contribute to prolonged and controlled drug release. RESULTS: Drug diffusion coefficients were: 1.38 · 10^?8m² s^?1 for Lidocaine hydrochloride and 5.96 · 10^?9m² s^?1 for Dihydroquercetin, while corresponding effective diffusion coefficients from hydrogels were: 7.82 · 10^?10m² s^?1 and 7.98 · 10^?10m² s^?1, respectively. Effective diffusion coefficients from liposome‐containing hydrogels were:4.82 · 10^?10m² s^?1 (Lidocaine hydrochloride) and 4.305 · 10^?10m² s^?1 (Dihydroquercetin). Diffusion resistances for the two hydrogels were almost the same. Very similar values of diffusion resistances for all liposome dispersions were obtained. CONCLUSION: Calculated diffusion coefficients and resistances demonstrate that liposomes, as drug carriers, significantly affect diffusion rates. The results obtained could be used whenever diffusion‐controlled drug release is required. Copyright © 2010 Society of Chemical Industry     

Graphene-supported platinum and platinum-ruthenium nanoparticles with high electrocatalytic activity for methanol and ethanol oxidation

In this study, Pt and Pt-Ru nanoparticles were synthesized on graphene sheets and their electrocatalytic activity for methanol and ethanol oxidation was investigated. Experimental results demonstrate that, in comparison to the widely-used Vulcan XC-72R carbon black catalyst supports, graphene-supported Pt and Pt-Ru nanoparticles demonstrate enhanced efficiency for both methanol and ethanol electro-oxidations with regard to diffusion efficiency, oxidation potential, forward oxidation peak current density, and the ratio of the forward peak current density to the reverse peak current density. For instance, the forward peak current density of methanol oxidation for graphene- and carbon black-supported Pt nanoparticles is 19.1 and 9.76 mA/cm², respectively; and the ratios are 6.52 and 1.39, respectively; the forward peak current density of ethanol oxidation for graphene- and carbon black-supported Pt nanoparticles is 16.2 and 13.8 mA/cm², respectively; and the ratios are 3.66 and 0.90, respectively. These findings favor the use of graphene sheets as catalyst supports for both direct methanol and ethanol fuel cells.     

Application of independent component analysis in removing artefacts from the electrocardiogram

Routinely recorded electrocardiograms (ECGs) are often corrupted by different types of artefacts and many efforts have been made to enhance their quality by reducing the noise or artefacts. This paper addresses the problem of removing noise and artefacts from ECGs using independent component analysis (ICA). An ICA algorithm is tested on three-channel ECG recordings taken from human subjects, mostly in the coronary care unit. Results are presented that show that ICA can detect and remove a variety of noise and artefact sources in these ECGs. One difficulty with the application of ICA is the determination of the order of the independent components. A new technique based on simple statistical parameters is proposed to solve this problem in this application. The developed technique is successfully applied to the ECG data and offers potential for online processing of ECG using ICA.     

Adaptation of Lactobacillus alimentarius to environmental stresses

Lactobacillus alimentarius BJ33 has been tested for its biopreservative capacities to improve quality and safety in many meat products. The combination of different preservatives such as NaCl, glucono-delta-lactone and citric acid with this protective culture during the manufacture of sausages represent an interesting alternative to control microbial spoilage and to extend product shelf life. The use of these preservatives may also limit the growth of L. alimentarius. In this study, the sublethal doses of these preservatives were determined and tested in combination to verify if the organism was able to adapt to these stresses. The sublethal doses of gluconic acid, citric acid, and NaCl were 100-110 mM, 50-55 mM and 8%, respectively. When the culture was first grown in MRS broth containing citric acid (50 or 55 mM) or gluconic acid (100 or 110 mM) and then transferred in MRS broth containing NaCl (8%), only limited growth was observed (O.D.(600 nm) = 0.2-0.3) after 6 days at 30 degrees C. However, when the culture was first grown in NaCl and then transferred in MRS broth containing gluconic or citric acid, growth was observed after 1 day (O.D.(600 nm) = 0.4-0.5) and after 5 days an O.D.(600 nm) of 0.8 was reached. Cell filamentation was also observed under electron microscopy when cells were grown for 2 days in presence of gluconic and citric acid at their sublethal doses and with a combination of 18 mM gluconic acid and 37 mM citric acid, but cellular elongation was not observed with cultures exposed to 8% NaCl. These results suggest that two different adaptation mechanisms are induced in L. alimenatrius when treated with organic acids and NaCl.