Investigation on the effects of microwave and conventional heating methods on the phytochemicals of pomegranate (Punica granatum L.) and black mulberry juices

Black mulberry and pomegranate juices were concentrated by conventional and microwave heating at different operational pressures (7.3, 12, 38.5, and 100 kPa). The effects of each heating method on the phytochemical changes (total anthocyanin content and antioxidant activity) of juices were investigated. The effect of various heating methods on the profile of the pomegranate anthocyanins were conducted using high-performance liquid chromatography–mass spectrometry (HPLC–MS). The main anthocyanins of pomegranate quantified by HPLC–MS were cyanidin, delphidin, pelargonidin, 3-glucoside, and 3, 5-diglucoside. In black mulberry juice, the final juice concentration of 42° Brix was achieved in 140, 120, and 95 min at 100, 38.5, and 7.3 kPa respectively and the final pomegranate juice concentration of 40° Brix was achieved in 140, 127, and 109 min at 100, 38.5, and 12 kPa respectively by using a rotary evaporator. Applying microwave energy decreased the required times to 115, 95, and 60 min for black mulberry juice and to 118, 95, and 75 min for pomegranate juice. Results showed that anthocyanin degradation and consequently decrease in antioxidant activity were more pronounced in rotary evaporation compared to microwave heating method.     

Three Basic Theorems in Numerical Analysis in Control Engineering Course and Their Application

International Journal of Control, Automation and Systems - Control system design packages like MATLAB, SICLAB, OCTAVE, etc. have become essential components of both undergraduate and graduate...     

An estimation of friction from the indentation of metals by acute-angled conical indenters

The paper describes a method for estimating the coefficient of friction (COF) between sliding surfaces by an indentation of an acute-angled indenter. The COF estimated by the method is compared with the COF measured by a friction tester. The conical indenter, which is made of WC and has an apex angle of 45°, is used for the experiments. A micro-Vickers hardness tester is used for the indentation tests. The friction tester used is one of Bowden–Leben type. A copper and a 0.45% carbon steel are used for the indentation and sliding specimens. The estimation of the COF is based on the equilibrium equation of indentation, which takes the friction between the contacting surfaces of the indenter and the specimen into consideration. The results show that the estimated COF is approximately equal to the measured one. Based on the results, the validity of this method is discussed.     

Curie Temperature Anomaly in Lead Zirconate Titanate/Silver Composites

The Curie temperatures of lead zirconate titanate-based (PZT-based) composites that were incorporated with silver particles were evaluated as a function of the silver content. Although the substitution of the silver ion has been considered to decrease the Curie temperature, PZT/silver composites exhibited higher Curie temperatures than those of monolithic PZT ceramics. It was found that the Curie temperature gradually increased as the silver content increased. It was suggested that the observed Curie temperature anomaly resulted from the relaxation of transformation-induced internal stress by intergranular silver particles.     

A Study of Polymer Electrolyte Fuel Cells by the Measurement of AC Impedance,Current Interrupt,and Dew Points: 2. Effect of Cell Temperature

The effect of cell temperature on the performance of a polymer electrolyte fuel cell was examined in the present study. Measurements using the current interrupt and AC impedance methods showed that membrane resistance increased as the cell temperature was reduced. The charge transfer resistance, determined by the AC impedance method, also increased with decreasing cell temperature. The results of electrochemical analysis showed that the temperature of the cell strongly affected the performance of the membrane–electrode assembly in the cell. In addition, the water balance calculated from dew points of fuel gases changed with cell temperature. At a cell temperature of 80 °C, ca. 80% of the water generated on the cathode passed through the membrane to the anode, while at a cell temperature of 40 °C, only ca. 20% of the water on the cathode passed through the membrane to the anode.     

Another approach to asymptotic model matching problem for nonlinear systems

This paper deals with the asymptotic model matching problem for square nonlinear systems. This problem has been studied by Di Benedetto and Grizzle via geometric approach. We adopt another approach. It is based on an idea that this problem is similar to the nonlinear servomechanism (output regulation) problem. By means of slight modification of the problem statement, a sufficient condition is given. It is described as the solvability of a certain partial differential equation. Its reduction and approximation methods are proposed. © 1998 John Wiley & Sons, Ltd.     

Densification behaviour of ceramic powder

A three-dimensional compaction device has been developed to carry out compaction of a ceramic powder. The details of the device, which provides compaction with various stress ratios, are described. A densification criterion for the powder is proposed; this is similar to that for the case for metal powders, but the role of the hydrostatic stress component appears to be different. Stress-strain rate relations are then derived using the concept of plastic potential; experimental results show that the normality of the strain rate vector to the surface which corresponds to the criterion almost holds.     

Challenges Upon Reactive Plasma Spray Nitriding: Al Powders and Fabrication of AlN Coatings as a Case Study

Reactive plasma spraying (RPS) is a promising technology for the in situ formation of several ceramic coatings. The focus of this paper is to summarize the state of our current knowledge about the RPS process and using the nitriding of Al particles and the fabrication of aluminum nitride coatings, as a case study. The aspects and challenges in this process such as the influence of the plasma power, in-flight time, particle size, nitriding mechanism, splat morphology, in-flight particle diagnostics, N₂ plasma gas, and the feeding rate on the RPS process are analyzed and discussed.     

Effects of bovine serum albumin on the corrosion behaviour of AISI 316L, Co–28Cr–6Mo, and Ti–6Al–4V alloys in phosphate buffered saline solutions

The corrosion behaviour of AISI 316L, wrought Co–28Cr–6Mo and Ti–6Al–4V was studied in aerated solutions of phosphate buffered saline (PBS) at various concentrations of bovine serum albumin (BSA) at 37 °C. Open circuit potential, potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) experiments along with X-ray photoelectron spectroscopy (XPS) on Co–28Cr–6Mo oxide layer were conducted to study the interaction of BSA and passive layers and to measure the corrosion rates. Ti–6Al–4V alloy had the lowest corrosion rate and the highest breakdown potential. It was shown that BSA has enhanced the alloy passive film stability at higher concentrations.