Measurement and control of pressure driven flows in microfluidic devices using an optofluidic flow sensor

Measurement and control of pressure-driven flow (PDF) has a great potential to enhance the performance of chemical and biological experiments in Lab on a Chip technology. In this paper, we present an optofluidic flow sensor for real-time measurement and control of PDF. The optofluidic flow sensor consists of an on-chip micro Venturi and two optical Fabry-Pérot (FP) interferometers. Flow rate was measured from the fringe shift of FP interferometers resulted from movement fluid in the on-chip micro Venturi. The experimental results show that the optofluidic flow sensor has a minimum detectable flow change of 5 nl/min that is suitable for real time monitoring and control of fluids in many chemical and biological experiments. A Finite Element Method is used to solve the three dimensional (3D) Navier–Stokes and continuity equations to validate the experimental results.     

An adaptive finite element procedure for crack propagation analysis

INTRODUCTION The finite element method (FEM) has proved to be very well suited for the study of fracture mechanics. Nevertheless, modelling the propagation of a crack through a finite element mesh turns out to be difficult because of the modification of the mesh topology. Use of crack propagation laws based on stress inten-sity factor range is the most successful engineering application of fracture mechanics. The stress intensity factors are a very important parameter in fracture analys…     

Antagonistic interaction between <Emphasis Type="Italic">Trichoderma asperellum</Emphasis> and <Emphasis Type="Italic">Phytophthora capsici</Emphasis> in vitro

Phytophthora capsici is a phytopathogen that causes a destructive pepper blight that is extremely difficult to control. Using a fungicide application against the disease is costly and relatively ineffective and there is also a huge environmental concern about the use of such chemicals. The genus Trichoderma has been known to have a potential biocontrol issue. In this paper we investigate the mechanism for causing the infection of T. asperellum against P. capsici. Trichoderma sp. (isolate CGMCC 6422) was developed to have a strong antagonistic action against hyphae of P. capsici through screening tests. The strain was identified as T. asperellum through using a combination of morphological characteristics and molecular data. T. asperellum was able to collapse the mycelium of the colonies of the pathogen through dual culture tests by breaking down the pathogenic hyphae into fragments. The scanning electron microscope showed that the hyphae of T. asperellum surrounded and penetrated the pathogens hyphae, resulting in hyphal collapse. The results show that seven days after inoculation, the hyphae of the pathogen were completely degraded in a dual culture. T. asperellum was also able to enter the P. capsici oospores through using oogonia and then developed hyphae and produced conidia, leading to the disintegration of the oogonia and oospores. Seven days after inoculation, an average 10.8% of the oospores were infected, but at this stage, the structures of oospores were still intact. Subsequently, the number of infected oospores increased and the oospores started to collapse. Forty-two days after inoculation, almost all the oospores were infected, with 9.3% of the structures of the oospores being intact and 90.7% of the oospores having collapsed.     

Learning communities and fair trade in doctorates and development: report of a collaborative project

This article reports the second stage of a study examining an academic partnership in which Bangladeshi doctoral students in a western university focus their research in the grounded context of Bangladesh and investigate the processes for change. After briefly outlining the previous published stage which examined the academic trade in higher education with developing countries, the article builds on the concept of fair academic trade to critically reflect on the development of a doctoral learning community, a publication project and three specific doctoral studies. The methodological approach is one of participatory action research, with focus on critical reflection on practice.     

Learner satisfaction,engagement and performances in an online module: Implications for institutional e-learning policy

Education and Information Technologies - There has been debates related to online and blended learning from a perspective of learner experiences in terms of student satisfaction, engagement and...     

Malaysian university students' attitudes to academic dishonesty and business ethics

Academic dishonesty is believed to have predictive ability for subsequent behaviours in the workplace. This study adds to the literature by investigating Malaysian business students' attitudes to academic dishonesty and their attitudes to ethics issues in business. This study also explores the association between these two constructs. The form of academic dishonesty being investigated here is related to assignments, quizzes, and examinations. Employing data collected from 153 business students from different academic years, this exploratory study concludes that business students may have found that some level of dishonesty is acceptable in some academic settings as well as in business settings. The study's outcomes highlight the possibility of using students' attitudes to academic dishonesty to explain their attitudes to ethics in business contexts. The findings of this study, to a certain extent, indicate that years spent in business education might contribute to such unfavourable attitudes. This exploratory study also draws attention to several issues related to the teaching of ethics within business education.     

Effects of within-class ability grouping on social interaction,achievement, and motivation

This study examined how grouping arrangements affect students achievement, social interaction, and motivation. Students of high, average and low ability were randomly assigned to homogeneous or heterogeneous ability groups. All groups attended the same plant biology course. The main results indicate that low-ability students achieve more and are more motivated to learn in heterogeneous groups. Average-ability students perform better in homogeneous groups whereas high-ability students show equally strong learning outcomes in homogeneous and heterogeneous groups. Results on social interaction indicate that heterogeneous groups produce higher proportions of individual elaborations, whereas homogeneous groups use relatively more collaborative elaborations. In the discussion, these differences in social interaction are used to explain the differential effects of grouping arrangements on achievement scores. Practical implications are discussed and topics for further research are advanced.     

Performance of passive and reactive profiled median barriers in traffic noise reduction

Median noise barriers, like parallel noise barriers, can be employed to reduce the impact of traffic on roadside communities via the direct propagation path. The performance of different shapes of median barriers was compared using reactive and passive surfaces and a 2D boundary element method (BEM). In the case of reactive surfaces, quadratic residue diffusers (QRDs) and primitive root diffusers (PRDs) were used on the top and stem surfaces of median barriers. To introduce passive barriers, two different absorbent materials including fibrous material and a grass surface with flow resistivity of 20 000 and 2500 kg/(s·m²), respectively, were similarly applied. The effect of thin absorptive barriers was similar at lower frequencies and better at mid and high frequencies to that of their equivalent rigid barriers. More improvement was achieved by covering the top surface of thick barriers with grass rather than with fibrous material. The performance of QRD and PRD barriers where the diffuser was located on the top surface was more frequency dependent than that of barriers coated with fibrous material. A comparison of the average A-weighted insertion loss in the thick barriers showed that the greatest improvement (2.59 dB (A)) was achieved using a barrier of 30-cm thickness covered with grass.