A micropillar array for sample concentration via in-plane evaporation

We present a method to perform sample concentration within a lab-on-a-chip using a microfluidic structure which controls the liquid-gas interface through a micropillar array fabricated in polydimethylsiloxane between microfluidic channels. The microstructure confines the liquid flow and a thermal gradient is used to drive evaporation at the liquid-gas-interface. The evaporation occurs in-plane to the microfluidic device, allowing for precise control of the ambient environment. This method is demonstrated with a sample containing 1 μm, 100 nm fluorescent beads and SYTO-9 labelled Escherichia coli bacteria. Over 100 s, the fluorescent beads and bacteria are concentrated by a factor of 10.     

Towards teaching analytics: a contextual model for analysis of students’ evaluation of teaching through text mining and machine learning classification

Education and Information Technologies - Recent trends in educational technology have led to emergence of methods such as teaching analytics (TA) in understanding and management of the...     

The application of SECI model as a framework of knowledge creation in virtual learning Case study of IUST Virtual Classes

The research aims to define SECI model of knowledge creation (socialization, externalization, combination, and internalization) as a framework of Virtual class management which can lead to better online teaching–learning mechanisms as well as knowledge creation. It has used qualitative research methodology including researcher’s close observation and attendance in the online MBA classes of Iran University of Science and Technology for one academic semester as well as semi-structured interviews with the professional facilitators. The article has defined a practical SECI framework in which 4 phases of socialization, externalization, combination, internalization, and their required “ba” contexts are explained with regards to tasks and responsibilities of both students and facilitators.     

Three dimensional passivated-electrode insulator-based dielectrophoresis

In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D πDEP) is presented. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D πDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 μm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D πDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 μl/h and 70% at flow rates as high as 750 μl/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape.     

An economic evaluation of Iranian public agricultural R&D policy: The case of sugarbeet

Despite its long tradition in the economic literature, there is no acceptable economic evaluation of Iranian public agricultural R&D policy mainly because of the lack of reliable estimates of supply shift parameter. Sugarbeet is chosen as a case for the estimation of the parameter using the method developed here and then the efficiency of the public investment in sugarbeet research is evaluated using the ordinary cost–benefit analysis. Research station records for 1982–2004 are used to estimate annual changes in beet attributes of root yield and sugar content and the estimates are used to make an evaluation of Iranian beet research investment. The results showed that the investment led to an average of 7.18% annual increase in beet sugar supply during the period (composing of +7.74% change in root yield index and −0.5% change in sugar content index) giving an internal rate of return of 32% (or an NPV/ha of $69) to this investment. It is concluded that although the investment has been profitable in comparison to other public investment projects, the efficiency of the policy is not comparable to that common in the literature and a revision in the policy is proposed.     

Testing a Model of Intercultural Willingness to Communicate based on Ethnocentrism,Ambiguity Tolerance and Sensation Seeking: The Role of Learning English in Iran

The present study aimed at testing a model of intercultural willingness to communicate based on ethnocentrism, ambiguity tolerance and sensation seeking between English and non-English major university students in Iran. A significant difference was found between the two groups on ethnocentrism and the results showed that the model fit the data adequately. Ethnocentrism was the strongest predictor of intercultural willingness to communicate for both groups. Sensation seeking was a significant predictor of intercultural willingness to communicate only for the non-English major university students. Moreover, sensation seeking and ambiguity tolerance were significant predictors of ethnocentrism.     

Evolution and adoption of contributor role ontologies and taxonomies

Contributor Role Ontologies and Taxonomies (CROTs) are standard vocabularies to describe individual contributions to a scholarly project or research output. Contributor Roles Taxonomy (CRediT) is one of the most widely used CROTs, and has been adopted by numerous journals to describe author's contributions, and recently formalized as a ANSI/NISO standard. Despite these developments, there is still much work left to be done to improve how CROTs are used across different research domains, research output types, and scholarly workflows. In this paper, we describe how CROTs could be extended to include roles from various disciplines in an ethical and inclusive manner. We explore potential approaches to apply CROTs to diverse research objects and various disciplines; as well as envision their integration into various scholarly workflows, such as promotion and tenure in academic institutions. Lastly, we discuss potential mechanisms for wide adoption and use. While acknowledging that improving current systems of attribution is a slow and iterative process, we believe that engaging the community in the evolution of CROTs will ultimately enhance the ethical attribution of credit and responsibilities in scholarly publications.     

A novel control strategy for load converter of DC isolated distribution system under unbalanced loading conditions

A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in the d-q-0 rotating coordinate based on symmetrical sequence components. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is a newly proposed control strategy based on the decomposition of the voltage and current into in- stantaneous positive, negative, and zero sequences. These three sequences are controlled independently in their own reference frames as DC signals. The performance of the load converter using these two control strategies is compared. Simulation results show the validity and capability of the newly proposed control strategy.