On the thermal conductivity of bimodal SiC/A356 composites fabricated via powder metallurgy route

The present study investigates the thermal conductivity of bimodal SiC particulate distribution in aluminum matrix composites fabricated via powder metallurgy route. The effects of the SiC_p reinforcement size distribution and processing parameters such as sintering time and temperature on the thermal conductivity have been examined. The Box–Behnken experimental array was employed to identify the effects of selected variables on the thermal conductivity of the composite. A reasonable augmentation in the thermal conductivity was observed with an increase in sintering time and %volume fraction of fine SiC particulates. It has been demonstrated that the matrix doped with fine SiC particulates (37?µm) occupied interstitial positions and formed continuous SiC–matrix network resulting in minimizing the micropores that contributed for good thermal conductivity, that is, 235?W/mK. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were conducted to evaluate the microstructure architecture and interfacial phase formation.     

Short anaerobiosis period prior to cold storage alleviates bitter pit and superficial scald in Granny Smith apples

BACKGROUND: Californian Granny Smith apples are very susceptible to bitter pit (BP) and superficial scald symptoms that develop during cold storage. The main preventive means are diphenylamine dipping and/or gaseous application of the ethylene inhibitor 1‐methylcylclopropene (1‐MCP), which is effective against superficial scald but not against BP. This study investigated the efficacy of a non‐chemical alternative, low‐O₂ (LO2) stress, in preventing these two physiological disorders. RESULTS: Application of LO2 stress at 20 °C for 10 days prior to cold storage of Granny Smith apples reduced superficial scald and BP incidence and severity during 8 months at 0 °C. LO2 treatments induced volatile alcohols and reduced ethylene and 6‐methyl‐5‐hepten‐2‐one (MHO‐on) production, thereby reducing superficial scald development after 4 months at 0 °C. In addition, LO2‐treated fruits had higher pectin methyl esterase (MdPME) gene expression, similar to that of 1‐MCP‐treated fruits, associated with their higher firmness. Conversion of MHO‐on to 6‐methyl‐5‐hepten‐2‐ol (MHO‐ol) in LO2‐treated fruits may explain the lower scald development. CONCLUSION: The ratio between MHO‐on and MHO‐ol might serve as an index of superficial scald severity. Reduction of BP symptoms in LO2‐treated fruits could be due to accumulation of volatile alcohols in the peel tissue. Copyright © 2010 Society of Chemical Industry     

Usability measurement and metrics: A consolidated model

Usability is increasingly recognized as an important quality factor for interactive software systems, including traditional GUIs-style applications, Web sites, and the large variety of mobile and PDA interactive services. Unusable user interfaces are probably the single largest reasons why encompassing interactive systems – computers plus people, fail in actual use. The design of this diversity of applications so that they actually achieve their intended purposes in term of ease of use is not an easy task. Although there are many individual methods for evaluating usability; they are not well integrated into a single conceptual framework that facilitate their usage by developers who are not trained in the filed of HCI. This is true in part because there are now several different standards (e.g., ISO 9241, ISO/IEC 9126, IEEE Std.610.12) or conceptual models (e.g., Metrics for Usability Standards in Computing [MUSiC]) for usability, and not all of these standards or models describe the same operational definitions and measures. This paper first reviews existing usability standards and models while highlighted the limitations and complementarities of the various standards. It then explains how these various models can be unified into a single consolidated, hierarchical model of usability measurement. This consolidated model is called Quality in Use Integrated Measurement (QUIM). Included in the QUIM model are 10 factors each of which corresponds to a specific facet of usability that is identified in an existing standard or model. These 10 factors are decomposed into a total of 26 sub-factors or measurable criteria that are furtherdecomposed into 127 specific metrics. The paper explains also how a consolidated model, such as QUIM, can help in developing a usability measurement theory. Ahmed Seffah interests are at the intersection of human-computer interaction and software engineering, with an emphasis on human-centered software engineering, empirical studies, theoretical models for quality in use measurement, as well as patterns as a vehicle for capturing and incorporating empirically valid design practices in software engineering practices. He is a co-founder of the Usability and Empirical Studies Lab and the founder and the chair of the Human-Centered Software Engineering Research Group at Concordia University. Harkirat K. Padda is a Ph.D. candidate at Concordia University (Montreal) since 2003, where she completed her masters’ degree in computer science. Her research interests are software quality measurement, metrics, and empirical software evaluation. Being a member of Human Computer Software Engineering Group, she is exploring the comprehension and usability of software systems—in particular the visualization systems. In her masters’ work, she already defined a repository of different metrics to measure the ‘quality in use’ factors of software products in general. Currently, she is proposing a pattern-oriented measurement framework to measure comprehension of visualization systems.     

Physico-chemical and organoleptic properties of patties from hot, chilled and frozen goat meat

The effects of processing hot versus chilled goat meat, as such and after freezing in chunk or mince forms, were studied in relation to physico-chemical and organoleptic properties of patties. The differences in the pH of the meat samples were non-significant (P < 0·05) at 3–4 h post mortem (PM) at room temperature (30°C) and after 24 h at 4°C. The yield of the broiled patties, prepared from hot meat at 3–4 h PM, was significantly lower (P<0·05) as compared to those from chilled meat. However, this trend was reversed, if processing of hot meat into patties was done within 1–2 h PM. Freezing of chilled meat in chunk or mince forms gave significantly higher (P < 0·05) cooking yields than freezing of hot meat in similar forms.

The organoleptic scores of the raw-cooked patties were similar for all treatments. Freezing of precooked patties at −10°C for 10 days, thawing and reheating did not reduce most of the sensory scores significantly (P<0·05). Moisture, protein and fat contents of the broiled patties were not significantly (P<0·05) affected by the treatments. Standard plate count of hot versus chilled meat, for all levels of processing and storage, were within acceptable limits.     

Assessment of positional error and hole quality during vibration-based drilling of aerospace alloy

Journal of Mechanical Science and Technology - Modulation assisted drilling (MAD) superimposes low frequency (&lt; 1000 Hz) and high amplitude (&lt; 150 µm) vibrations to the cutting...     

Detecting and responding to hostile disinformation activities on social media using machine learning and deep neural networks

Neural Computing and Applications - Disinformation attacks that make use of social media platforms, e.g., the attacks orchestrated by the Russian “Internet Research Agency” during the...     

Methodology optimization for quantification of total phenolics and individual phenolic acids in sweetpotato (Ipomoea batatas L.) roots

ABSTRACT:  Phenolic acids are one of the several classes of naturally occurring antioxidant compounds found in sweetpotatoes. Simplified, robust, and rapid methodologies were optimized to quantify total and individual phenolic acids in sweetpotato roots. Total phenolic acid content was quantified spectrophotometrically using both Folin–Denis and Folin–Ciocalteu reagents. The Folin–Ciocalteu reagent gave an overestimation of total phenolic acids due to the absorbance of interfering compounds (that is, reducing sugars and ascorbic acid). Individual phenolic acids were quantified by high-performance liquid chromatography (HPLC) using the latest in column technology. Four reversed-phase C18 analytical columns with different properties (dimensions, particle size, particle shape, pore size, and carbon load) were compared. Three different mobile phases using isocratic conditions were also evaluated. A column (4.6 × 150 mm) packed with 5-μm spherical silica particles of pore size 110 Å combined with 14% carbon load provided the best and fast separation of individual phenolic acids (that is, chlorogenic acid, caffeic acid, and 3 isomers of dicaffeoylquinic acid) with a total analysis time of less than 7 min. Among the 3 mobile phases tested, a mobile phase consisting of 1% (v/v) formic acid aqueous solution: acetonitrile: 2-propanol, pH 2.5 (70:22:8, v/v/v) gave adequate separation. Among the solvents tested, aqueous mixtures (80:20, solvent:water) of methanol and ethanol provided higher phenolic acid extraction efficiency than the aqueous mixture of acetone.     

Phenolic composition and antioxidant capacity of different heat-processed forms of sweetpotato cv. 'Beauregard'

Sweetpotato [ Ipomoea batatas (L.) Lam.] cv. 'Beauregard' roots were cooked using three different heat-processing techniques (baked in a conventional oven, baked in a microwave oven, and boiled). Total phenolic content, individual phenolic acids, and antioxidant capacity were determined using Folin-Denis assay, HPLC (high-performance liquid chromatography), and DPPH (1,1-diphenyl-2-picrylhydazyl) assay, respectively. The skin tissue (raw or processed) contained the highest concentration of total phenolics. All heat-processing methods resulted in a significant loss in total phenolic content and antioxidant capacity of the skin tissue. However, compared with the other processing methods, conventional oven baking resulted in greater losses in antioxidant capacity of skin tissue. Total phenolic content ranged from a low of 1.58 mg chlorogenic acid equivalent g⁻¹ dry tissue weight in boiled pith tissue to a high of 17.7 mg chlorogenic acid equivalent g⁻¹ dry tissue weight in raw skin tissue. The antioxidant capacity was highest in raw skin tissue (22.9 mg Trolox equivalent g⁻¹ dry tissue weight). Chlorogenic acid was the principal phenolic acid found in all sweetpotato tissues. Caffeic acid and three isomers of dicaffeoylquinic acid (diCQA) were also identified and quantified.