Technologies, Volume 3, Issue 4 (December 2015) – 7 articles , Pages 182-320

Thousands of tons of macadamia skin waste are generated annually with very limited utilisation of this extensive by-product. The aim of this study was to develop optimal ultrasonic extraction conditions for maximized recovery of phenolic compounds and antioxidant properties from macadamia skin using Response Surface Methodology (RSM). Three ultrasonic parameters, including temperature (30–50 °C), time (10–50 min) and power (150–250 W), were tested for their impact on the extraction of total phenolic compounds (TPC), flavonoids, proanthocyanidins and antioxidant properties. The results showed that ultrasonic temperature, time and power had an impact on TPC and antioxidant capacity; however, the effects varied. The optimum ultrasonic conditions for the maximum recovery of phenolic compounds and antioxidant properties from macadamia skin were found to be a temperature of 40 °C, a time of 35 min and a power of 80%/200 W. Under these optimal conditions, approximately 168 mg of TPC, 135 mg of flavonoids and 188 mg of proanthocyanidins can be extracted from one gram of dried macadamia skin. Full article

Helicteres hirsuta Lour. (H. hirsuta L.) is widely distributed in southeast Asian countries and has been used traditionally as a medicinal plant. However, optimal conditions for preparation of dried materials for further processing and suitable solvents for the extraction of bioactive compounds have not been investigated. The objective of this study was to evaluate the effects of different extraction solvents and different drying conditions on the physicochemical properties and antioxidant capacity of the H. hirsuta L. leaves. The results showed that both extraction solvents and drying conditions had a significant impact on physicochemical and antioxidant properties of H. hirsuta L. leaves. Among the five solvents investigated, water could extract the highest level of solid content and phenolic compounds, whereas methanol was more effective for obtaining flavonoids and saponins than other solvents. The leaves dried under either hot-air drying at 80 °C (HAD80), or vacuum drying at 50 °C (VD50) yielded the highest amount of total phenolic compounds (7.77 and 8.33 mg GAE/g, respectively) and total flavonoid content (5.79 and 4.62 mg CE/g, respectively), and possessed the strongest antioxidant power, while leaves dried using infrared drying at 30 °C had the lowest levels of bioactive compounds. Phenolic compounds including flavonoids had a strong correlation with antioxidant capacity. Therefore, HAD80 and VD50 are recommended for the preparation of dried H. hirsuta L. leaves. Water and methanol are suggested solvents to be used for extraction of phenolic compounds and saponins from H. hirsuta L. leaves for the potential application in the nutraceutical and pharmaceutical industries. Full article

The present paper talks about the free vibration analysis of simply supported Single- and Double-Walled Carbon Nanotubes (SWCNTs and DWCNTs). Refined 2D Generalized Differential Quadrature (GDQ) shell methods and an exact 3D shell model are compared. A continuum approach (based on an elastic three-dimensional shell model) is used for natural frequency investigation of SWCNTs and DWCNTs. SWCNTs are defined as isotropic cylinders with an equivalent thickness and Young modulus. DWCNTs are defined as two concentric isotropic cylinders (with an equivalent thickness and Young modulus) which can be linked by means of the interlaminar continuity conditions or by means of van der Waals interactions. Layer wise approaches are mandatory for the analysis of van der Waals forces in DWCNTs. The effect of van der Waals interaction between the two cylinders is shown for different DWCNT lengths, diameters and vibration modes. The accuracy of beam models and classical 2D shell models in the free vibration analysis of SWCNTs and DWCNTs is also investigated. Full article

A new carbon fiber reinforced polymer (CFRP) anchor is developed and tested to delay debonding in reinforced concrete (RC) beams externally strengthened with FRP laminate/sheet. The C-shape anchor is made from a commercially available CFRP grid. The anchors legs are 95 mm long while the spacing between the legs is adjustable, depending on FRP laminate and beam widths. Nine full scale RC beams, 3.0 m long, 250 mm wide and 400 mm deep, were strengthened with CFRP laminate/sheet, with and without the C-anchor. The main test parameters were the type and amount of FRP laminate and the presence/absence of the anchor. Test results showed that beams with the anchor had generally 5%–10% higher debonding and failure load, and they reached higher deflection at failure than the companion beams without anchors. Although complete separation of the FRP laminate from the concrete was not observed in any of the beams with anchors, there was noticeable slip at failure at one end of the laminate. A significant outcome of the study is that anchors are effective in limiting the extent of debonding along the laminate, thus contributing to the flexural stiffness of the beam by reducing the extent of cracking and limiting the crack width along the beam. Finally, the anchor allowed the FRP to reach or exceed its theoretically allowable strain computed based on the American Concrete Institute (ACI) Committee 440 recommendation while in none of the beams without anchors, the FRP reached its theoretically allowable strain. Full article

An intrinsic limitation of the accuracy that can be achieved with Compton cameras results from the inevitable fact that the detectors, which comprise the camera, cannot have infinitely-accurate spatial resolution. To mitigate this loss of accuracy, a new imaging model is proposed. The implementation of the new imaging model, however, requires new camera designs. The results of a computer simulation indicate that the new imaging model can produce reasonable images, at least when noiseless simulated data are used. In the future, more work is needed to determine if the use of the new imaging model will improve the imaging capabilities of Compton cameras despite the loss of sensitivity caused by the use of the new camera designs. Regardless of the outcome of this work, the results presented here illustrate that new models for imaging from Compton scatters are possible and motivate the development of further models that could be more advantageous than the ones already developed. Full article

The purpose of this study is to revisit the relationship among information technology (IT), Process, and Strategy. We focus on the impact of mobile Point of Sales (mPOS) on changing of operational processes in the restaurant industry. This study investigates the changing of IT strategy and service strategy. The research model was developed based on the literature (strategic alignment model and situated change perspective) and inputs from the restaurant industry and IT experts. The data of this study are collected from observation and face-to-face interviews with both business and IT personnel from 10 restaurants in Taiwan. The findings of this study provide a comprehensive view about the ways processes change once restaurants implements mPOS. We also figure out the impact of this change on IT strategy and service strategy. This study’s results shed new light on IT implementation. Researchers need to look at IT in different ways and suggest suitable solutions for practitioners. Full article

Microwaves at the ISM (Industrial, Scientific and Medical, reserved internationally) frequency of 2450 or 5800 MHz have been used to prepare FeCoNiCuAl, FeCrNiTiAl and FeCoCrNiAl_2.5 high entropy alloys by direct heating of pressed mixtures of metal powders. The aim of this work is to explore a new microwave-assisted near-net-shape technology, using a powder metallurgy approach for the preparation of high entropy alloys, able to overcome the limits of current melting technologies (defects formation) or solid state ones (time demanding). High entropy alloy compositions have been selected so as to comprise at least one ferromagnetic element and one highly reactive couple, like Ni-Al, Ti-Al, Co-Al or Fe-Al. Results show that direct microwave heating of the powder precursors occurs, and further heating generation is favored by the ignition of exothermal reactions in the load. Microwaves have been applied both for the ignition and sustaining of such reactions, showing that by the proposed technique, it is possible to control the cooling rate of the newly-synthesized high entropy alloys. Results showed also that microwave heating in predominant magnetic field regions of the microwave applicator is more effective at controlling the cooling rate. The herein proposed microwave-assisted powder metallurgy approach is suitable to retain the shape of the load imparted during forming by uniaxial pressing. The homogeneity of the prepared high entropy alloys in all cases was good, without the dendritic segregation typical of arc melting, even if some partially-unreacted powders were detected in the samples. Full article