Exfoliated Graphite Nanoplatelet-Carbon Nanotube Hybrid Composites for Compression Sensing

In this study, we investigated the gauge factor and compressive modulus of hybrid nanocomposites of exfoliated graphite nanoplatelets (xGnP) and multiwalled carbon nanotubes (MWCNTs) in a polydimethylsiloxane matrix under compressive strain. Mechanical and electrical tests were conducted to investigate the effects of nanofiller wt %, the xGnP size, and xGnP:MWCNT ratio on the compressive modulus and sensitivity of the sensors. It was found that nanofiller wt %, the xGnP size, and xGnP:MWCNT ratio significantly affect the electromechanical properties of the sensor. The compressive modulus increased with an increase in the nanofiller wt % and a decrease in the xGnP size and xGnP:MWCNT ratio. However, the gauge factor decreases with a decrease in the nanofiller wt % and xGnP size and an increase in the xGnP:MWCNT ratio. Therefore, by investigating the piezoresistive effects of various factors for sensing performance, such as wt %, xGnP size, and xGnP:MWCNT ratio, the concept of one- and two-dimensional hybrid fillers provides an effective way to tune both mechanical properties and sensitivity of nanocomposites by tailoring the network structure of fillers

The effect of computer-mediated discussion on L2 academic writing in a composition course for ESL students

textThis dissertation research investigated the role of online discussion in students’ experience in an academic writing class. As an intervention study, I implemented 20-minute-long online discussions at the end of every class period over a semester as part of required class activities and measured students’ subsequent timed writings and their first and final essays to trace some possible influence from online discussion to their writing development. Topics for online discussions were organized according to course objectives and the day’s lesson, with students developing subtopics reflecting their own interest according to the evolution of each discussion. These topics included theoretical concepts on academic writing as well as orthographical, lexical, grammar, and discourse-related inquiries. Participants included 10 treatment and 12 control students registered in two sections of a rhetoric and composition course designated for non-native English speaking students at a private university. This course was not an ESL class, but was part of the regular composition course offerings, except that it was restricted to international students specifically. Data sources included the treatment group’s 26 online discussion transcripts, 12 sets of timed writings, individual interviews, field notes, two types of essays, and surveys. The control group contributed essays, one set of timed writing taken in the middle of the semester, survey responses, five class recordings, and an instructor interview. Data analysis was performed by using a mixed method approach. Results from online discussion transcripts revealed that treatment students made use of online discussions for their learning, shown through types and characteristics of language-, content-, and writing-related episodes and the semester-long changes and pattern in such talk. Interviews and survey data showed students’ positive learning experiences and changes in their perception toward computer-mediated learning experiences over the semester. In terms of students’ writing, the treatment group made significant improvement in their timed writings over the semester and also outperformed the control group in essay writing significantly, in five of seven categories on a writing rubric. The most significant finding from this study was the improvement of treatment students’ writing scores over the semester. This study suggests the possible value of incorporating computer-mediated instruction in writing instruction as well as future research ideas that bridge research on traditional L2 writing and technology-enriched language learning.Foreign Language Educatio

Improvement of retinoids production in recombinant E. coli using glyoxylic acid

Isoprenoids are the most chemically diverse compounds found in nature. They are present in all organisms and have essential roles in membrane structure, redox chemistry, reproductive cycles, growth regulation, signal transduction and defense mechanisms. In spite of their diversity of functions and structures, all isoprenoids are derived from the common building blocks of isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP). Optimization of IPP synthesis pathway is of benefit to mass production of various isoprenoids. There are two pathways of 2-C-Methyl-D-erythritol-4-phosphate (MEP) and mevalonate (MVA) for IPP synthesis. Prokaryotes including E. coli generally use MEP pathway whereas MVA pathway is used in eukaryotes. To improve isoprenoid production, it was performed the deletion of genes in E. coli, which are involved in both formation of fermentation by-products such as organic acids and alcohols, and consumption of precursors of MEP and MVA pathways, pyruvate and acetyl-CoA. As a result, we were able to develop a strain with improved fermentation productivity and carbon source utilization efficiency, the mutant strain was called AceCo. Higher lycopene production was achieved in the AceCo strain compared to the wild type MG1655 strain due to no formation of the inhibitory by-products. However, retinoids production of AceCo strain decreased to a half of that of MG1655 strain. Please click Additional Files below to see the full abstract

Influence of Blade Pass Frequency Vibrations on MCSA-based Rotor Fault Detection of Induction Motors

(c) 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works[EN] Motor current signature analysis (MCSA) has recently become widespread in industry for on-line detection of rotor cage faults in induction motors for preventing forced outages. Although it can provide low cost, remote monitoring of rotor faults, cases of false indications have been reported, where the causes of some false indications are still unknown. It is shown for the first time in this work that high-amplitude blade pass frequency (BPF) vibrations produced in pumps, fans, or compressors can cause false rotor fault indications, if the number of motor poles is an integer multiple of the number of blades. The influence of BPF vibration on MCSA based rotor fault detection is analyzed, and it is shown that the interaction between BPF vibration and rotor faults can produce false positive and negative fault indications. Alternative test methods capable of separating the influence of the BPF vibration and rotor faults are suggested for avoiding false MCSA alarms. The claims made in the paper are verified experimentally on a custom-built 380 V induction motor-centrifugal pump system setup.This work was supported in part by the Human Resources program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry, and Energy, Requblic of Korea, under Grant 20154030200610, and in part by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education under Grant 2016R1D1A1A09917190.Park, Y.; Jeong, M.; Sang Bin Lee; Antonino-Daviu, J.; Teska, M. (2017). Influence of Blade Pass Frequency Vibrations on MCSA-based Rotor Fault Detection of Induction Motors. IEEE Transactions on Industry Applications. 53(3):2049-2058. doi:10.1109/TIA.2017.2672526S2049205853

Chemical composition and anti-inflammatory activity of essential oils from resin of Commiphora species

ABSTRACT. Essential oils (EOs) were prepared by the hydro-distillation technique from the resins of four Commiphora species and analyzed by GC-MS. Major constituents of EOs were a-copaene (22.71%), β-caryophyllene (28.03%) and β-caryophyllene oxide (13.89%) for C. sphaerocarpa; a-pinene (29.1%) for C. africana; hexadecane (14.1%) for C. habessinica and δ-cadinene (31.5%) for C. schimperi. We investigated the anti-inflammatory effects of EOs in lipopolysaccharide (LPS) stimulated RAW 264.7 macrophages by measuring nitric oxide (NO). The effect in mRNA or protein level after EO treatment were evaluated by RT-PCR and Western blot analysis, respectively. Among four Commiphora species, C. sphaerocarpa EO demonstrated a significant inhibition of LPS by 27.2±3.6% at 10 μg/mL and 62.3±5.2% at 20 μg/mL. C. sphaerocarpa EO inhibited LPS mediated iNOS over expression in both protein and mRNA level with dose dependent manner. It inhibited phosphorylation of ERK1/2, p38, ATF2. The enhanced anti-inflammatory activity of the EO of the plant was due to HO-1 expression by ROS dependent Nrf2 activation in RAW264.7 cells. These findings indicate C. sphaerocarpa EO inhibits the pro-inflammatory responses by inhibiting MAPK/ATF2, and triggering ROS/Nrf2/HO-1 signaling. Therefore, C. sphaerocarpa EO could have potential for useful therapeutic candidate preventing and treating inflammatory diseases.   KEY WORDS: GC-MS, Anti-inflammatory, C. africana, C. habessinica, C. sphaerocarpa, C. schimperi   Bull. Chem. Soc. Ethiop. 2022, 36(2), 399-415.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i2.13                                                     &nbsp

Sequential whole cell conversion process for production of D-psicose and D- mannitol from D-fructose

Rare sugars, which exist only limited quantities naturally, have received considerable attention because of its various specific nutritional and biological functions. Likewise, D-psicose (D-ribo-2-hexulose or D-allulose), a C-3 epimer of D-fructose, has many uses which include reducing intra-abdominal fat accumulation, protecting pancreas beta-islets and improving insulin sensitivity. Especially, D-psicose has only 0.3% calories compared to sucrose, while it has 70% relative sweetness. Additionally, in 2012, D-psicose was approved as a food additive and designated as Generally Recognized As Safe (GRAS) by Food and Drug Administration (FDA). Despite such abundant advantages, there is no economical way of mass production of D-psicose. Recently, biological production of D-psicose from D-fructose using D-psicose 3-epimerase (DPE) has been developed. However, the conversion yield is below 30%, which causes an undesirable increase of purification cost because of the similar solubility of D-psicose and D-fructose. Thus, we addressed the problem by converting the residual fructose, after the reaction of D-psicose production, to D-mannitol, which has a low solubility. The sequential whole cell conversion reactions for D-psicose and D-mannitol allow a convenient and economic purification of both products. This work was supported by a grant from the Next-Generation BioGreen 21 Program (SSAC, grant#: PJ01106201), RDA, Korea. Reference 1) Carsten Bäumchen & Stephanie Bringer-Meyer (2007), Expression of glf Z.m. increases D-mannitol formation in whole cell biotransformation with resting cells of Corynebacterium glutamicum, Appl Microbiol Biotechnol 76(3):545–52. 2) Ortiz, M. E., Bleckwedel, J., Raya, R. R., & Mozzi, F. (2013). Biotechnological and in situ food production of polyols by lactic acid bacteria, Appl Microbiol Biotechnol 97:4713-4726 3) Park, Y., Oh, E. J., Jo, J., Jin, Y., & Seo, J. (2016). Recent advances in biological production of sugar alcohols. Curr Opin Biotechnol 37:105–113

Spatial rank-based multifactor dimensionality reduction to detect gene–gene interactions for multivariate phenotypes

Background Identifying interaction effects between genes is one of the main tasks of genome-wide association studies aiming to shed light on the biological mechanisms underlying complex diseases. Multifactor dimensionality reduction (MDR) is a popular approach for detecting gene–gene interactions that has been extended in various forms to handle binary and continuous phenotypes. However, only few multivariate MDR methods are available for multiple related phenotypes. Current approaches use Hotellings T2 statistic to evaluate interaction models, but it is well known that Hotellings T2 statistic is highly sensitive to heavily skewed distributions and outliers. Results We propose a robust approach based on nonparametric statistics such as spatial signs and ranks. The new multivariate rank-based MDR (MR-MDR) is mainly suitable for analyzing multiple continuous phenotypes and is less sensitive to skewed distributions and outliers. MR-MDR utilizes fuzzy k-means clustering and classifies multi-locus genotypes into two groups. Then, MR-MDR calculates a spatial rank-sum statistic as an evaluation measure and selects the best interaction model with the largest statistic. Our novel idea lies in adopting nonparametric statistics as an evaluation measure for robust inference. We adopt tenfold cross-validation to avoid overfitting. Intensive simulation studies were conducted to compare the performance of MR-MDR with current methods. Application of MR-MDR to a real dataset from a Korean genome-wide association study demonstrated that it successfully identified genetic interactions associated with four phenotypes related to kidney function. The R code for conducting MR-MDR is available at https://github.com/statpark/MR-MDR Conclusions Intensive simulation studies comparing MR-MDR with several current methods showed that the performance of MR-MDR was outstanding for skewed distributions. Additionally, for symmetric distributions, MR-MDR showed comparable power. Therefore, we conclude that MR-MDR is a useful multivariate non-parametric approach that can be used regardless of the phenotype distribution, the correlations between phenotypes, and sample size.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (2013M3A9C4078158, NRF-2021R1A2C1007788)

Identification of Vulnerable Plaque in a Stented Coronary Segment 17 Years after Implantation Using Optical Coherence Tomography

A patient presented with exertional chest pain two months prior to admission. Coronary angiography revealed a subocclusive stenosis within the boundaries of the stent. Optical coherence tomography showed remarkable intimal growth inside the stent, which demonstrated a heterogeneous appearance including low-intensity areas. These findings were congruent with the morphology of fibroatheroma in the native coronary artery and suggested that new atherosclerotic progression of the intima within the stent had occurred over 17 years following bare metal stent implantation. To the best of our knowledge, this is one of the most delayed instances of a bare metal stent restenosis described in the medical literature