Effects Of Web-Based Interactive Modules On Engineering Students’ Learning Motivations

The purpose of this study is to assess the impact of a newly developed modules, Interactive Web-Based Visualization Tools for Gluing Undergraduate Fuel Cell Systems Courses system (IGLU), on learning motivations of engineering students using two samples (n1=144 and n2=135) from senior engineering classes. The multivariate analysis results revealed that the participants had a significant increase in their learning motivation after the treatment with the IGLU modules. This result was cross-validated with the two samples, in which the motivation mean posttest scores are significantly higher than the mean pretest scores, systematically (Sample 1: the mean score is increased by 2.09 [.32, 3.87] points, p = .021; Sample 2: the mean score is increased by 1.38 [.14, 2.61] points, p = .029). With the use of instructional technology prevailing in current university courses, the education initiative of the IGLU system and the assessment of its impact on student learning motivation provide us information to improve the modules to serve a more diverse student body. It will greatly help the development of engineering educational curriculum. With regards to the statistical inference, it is desirable to conduct further studies with a quasi-experiment control group design to assess the program effect focusing on student learning and its associations with student learning motivations and learning styles

Disappearance of Transverse Flow in Central Collisions for Heavier Nuclei

For the first time, mass dependence of balance energy only for heavier systems has been studied. Our results are in excellent agreement with the data which allow us to predict the balance energy of U+U, for the first time, around 37-39 MeV/nucleon. Also our results indicate a hard equation of state along with nucleon-nucleon cross-section around 40 mb.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

DNS of vertical plane channel flow with finite-size particles: Voronoi analysis, acceleration statistics and particle-conditioned averaging

We have performed a direct numerical simulation of dilute turbulent particulate flow in a vertical plane channel, fully resolving the phase interfaces. The flow conditions are the same as those in the main case of "Uhlmann, M., Phys. Fluids, vol. 20, 2008, 053305", with the exception of the computational domain length which has been doubled in the present study. The statistics of flow and particle motion are not significantly altered by the elongation of the domain. The large-scale columnar-like structures which had previously been identified do persist and they are still only marginally decorrelated in the prolonged domain. Voronoi analysis of the spatial particle distribution shows that the state of the dispersed phase can be characterized as slightly more ordered than random tending towards a homogeneous spatial distribution. It is also found that the p.d.f.'s of Lagrangian particle accelerations for wall-normal and spanwise directions follow a lognormal distribution as observed in previous experiments of homogeneous flows. The streamwise component deviates from this law presenting significant skewness. Finally, a statistical analysis of the flow in the near field around the particles reveals that particle wakes present two regions, a near wake where the velocity deficit decays as 1/x and a far wake with a decay of approximately 1/(x*x).Comment: accepted for publication in Int. J. Multiphase Flo

Designing Durable Vapor-Deposited Surfaces for Reduced Hydrate Adhesion

The formation and accumulation of clathrate hydrates inside oil and gas pipelines cause severe problems in deep-sea oil/gas operations. In the present work, durable and mechanically robust bilayer poly-divinyl benzene/poly(perfluorodecylacrylate) coatings are developed using initiated chemical vapor deposition (iCVD) to reduce the adhesion strength of hydrates to underlying substrates (silicon and steel). Tetrahydrofuran (THF) dissolved in water with a wt% concentration of 0–70 is used to study the formation of hydrates and their adhesion strength. Goniometric measurements of the THF–water droplets on the substrates exhibit a reduction in advancing and receding contact angles with an increase in the THF concentration. The strength of hydrate adhesion experiences a tenfold reduction when substrates are coated with these iCVD polymers: from 1050 ± 250 kPa on bare silicon to 128 ± 100 kPa on coated silicon and from 1130 ± 185 kPa on bare steel to 153 ± 86 kPa on coated steel. The impact of subcooling temperature and time on the adhesion strength of hydrate on substrates is also studied. The results of this work suggest that the THF–water mixture repellency of a given substrate can be utilized to assess its hydrate-phobic behavior; hence, it opens a pathway for studying hydrate-phobicity.Chevron Corporation (MIT-Chevron University Partnership Program

Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)

Transforming plant biology and breeding with CRISPR/Cas9, Cas12 and Cas13

Currently, biology is revolutionized by ever growing applications of the CRISPR /Cas system. As discussed in this Review, new avenues have opened up for plant research and breeding by the use of the sequence‐specific DN ases Cas9 and Cas12 (formerly named Cpf1) and, more recently, the RN ase Cas13 (formerly named C2c2). Although double strand break‐induced gene editing based on error‐prone nonhomologous end joining has been applied to obtain new traits, such as powdery mildew resistance in wheat or improved pathogen resistance and increased yield in tomato, improved technologies based on CRISPR /Cas for programmed change in plant genomes via homologous recombination have recently been developed. Cas9‐ and Cas12‐ mediated DNA binding is used to develop tools for many useful applications, such as transcriptional regulation or fluorescence‐based imaging of specific chromosomal loci in plant genomes. Cas13 has recently been applied to degrade mRNA s and combat viral RNA replication. By the possibility to address multiple sequences with different guide RNA s and by the simultaneous use of different Cas proteins in a single cell, we should soon be able to achieve complex changes of plant metabolism in a controlled way