bluuebunny/crossref_metadata_2025 huggingface dataset:
Apigenin Attenuates Acetaminophen-Induced Hepatotoxicity by Activating AMP-Activated Protein Kinase/Carnitine Palmitoyltransferase I Pathway
Authors: Zhang Jiaqi , Liang Xiaoqiang , Li Jiacheng , Yin Hao , Liu Fangchen , Hu Cheng , Li Ling
Published: November 2020

Overuse of acetaminophen (APAP) is a major cause of drug-induced liver failure at the clinics. Apigenin (API) is a natural flavonoid derived from Matricaria chamomilla. The aim of the present study was to investigate the amelioration function of API in APAP-induced hepatotoxicity both in vitro and in vivo and investigate its potential mechanisms. Analysis results of the activities of serum alanine and aspartate aminotransferases (ALT and AST), malondialdehyde, myeloperoxidase (MPO), and reactive oxygen species (ROS) demonstrated therapeutic effects of API. MTT assay results revealed that API attenuated APAP and its metabolic product, N-acetyl-p-benzoquinone imine (NAPQI) induced cytotoxicity in a dose-dependent manner in human liver cells, L-02 cells. Subsequently, metabolomic results of cells and serum analyses demonstrated an aberrant level of carnitine palmitoyltransferase I (CPT1A). We established that API stimulated CPT1A activity in mice liver tissues and L-02 cells. Molecular docking analyses revealed potential interaction of API with CPT1A. Further investigation of the role of CPT1A in L0-2 cells revealed that API reversed cytotoxicity via the AMP-activated protein kinase (AMPK)/GSK-3β signaling pathway and compound C, which is a selective AMPK inhibitor, inhibited activation of CPT1A induced by API. API was bound to the catalytic region of AMPK as indicated by molecular docking results. In addition, compound C suppressed nuclear translocation of nuclear factor erythroid 2–related factor 2 (NRF2) that is enhanced by API and inhibited the antioxidative function of API. In summary, the study demonstrates that API attenuates APAP-induced hepatotoxicity by activating the AMPK/GSK-3β signaling pathway, which subsequently promotes CPT1A activity and activates the NRF2 antioxidant pathway.
A Close Relationship Between Networks of Interstitial Cells of Cajal and Gastrointestinal Transit In Vivo
Authors: Kishi Kazuhisa , Kamizaki Moe , Kaji Noriyuki , Iino Satoshi , Hori Masatoshi
Published: November 2020

The interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are located in the same area as the myenteric plexus. ICC-MP networks are linked to the generation of electrical pacemaker activity that causes spontaneous gastrointestinal (GI) contractions; however, its role in GI transit is not clear. The aim of this study was to comprehensively investigate the effect of ICC-MP disruption on GI transit in vivo using W/Wv mice, partially ICC-deficient model mice. In this study, we measured GI transit using a 13C-octanoic acid breath test, an orally administered dye and a bead expulsion assay. ICC were detected by immunohistochemical staining for c-Kit, a specific marker for ICC. Interestingly, we found that gastric emptying in W/Wv mice was normal. We also found that the ability of small intestinal and colonic transit was significantly reduced in W/Wv mice. Immunohistochemical staining using whole-mount muscularis samples revealed that c-Kit-positive ICC-MP networks were formed in wild-type mice. In contrast, ICC-MP networks in W/Wv mice were maintained only in the gastric antrum and were significantly reduced in the ileum and colon. No significant changes were observed in the nerve structures of the myenteric plexus in W/Wv mice. These findings suggest that ICC-MP contribute to GI transit as a powerful driving function in vivo.
Aspirin Eugenol Ester Protects Vascular Endothelium From Oxidative Injury by the Apoptosis Signal Regulating Kinase-1 Pathway
Authors: Huang Mei-Zhou , Zhang Zhen-Dong , Yang Ya-Jun , Liu Xi-Wang , Qin Zhe , Li Jian-Yong
Published: November 2020

Aspirin eugenol ester (AEE) is a new potential pharmaceutical compound possessing anti-inflammatory, anti-cardiovascular disease, and antioxidative stress activity. The pharmacological activities of AEE are partly dependent on its regulation of cell apoptosis. However, it is still unclear how AEE inhibits cell apoptosis on the basis of its antioxidative stress effect. This study aimed to reveal the vascular antioxidative mechanism of AEE in response to H2O2-induced oxidative stress in HUVECs and paraquat-induced oxidative stress in rats. In the different intervention groups of HUVECs and rats, the expression of ASK1, ERK1/2, SAPK/JNK, and p38 and the phosphorylation levels of ERK1/2, SAPK/JNK, and p38 were measured. The effects of ASK1 and ERK1/2 on the anti-apoptotic activity of AEE in the oxidative stress model were probed using the corresponding inhibitors ASK1 and ERK1/2. The results showed that in the HUVECs, 200 μM H2O2 treatment significantly increased the phosphorylation of SAPK/JNK and the level of ASK1 but decreased the phosphorylation of ERK1/2, while in the HUVECs pretreated with AEE, the H2O2-induced changes were significantly ameliorated. The findings were observed in vitro and in vivo. Moreover, inhibition of ASK1 and ERK1/2 showed that ASK1 plays a vital role in the protective effect of AEE on H2O2-induced apoptosis. All findings suggested that AEE protects the vascular endothelium from oxidative injury by mediating the ASK1 pathway.
Mechanistic Insights Into the Reduced Pacemaking Rate of the Rabbit Sinoatrial Node During Postnatal Development: A Simulation Study
Authors: Alghamdi Azzah M. , Testrow Craig P. , Whittaker Dominic G. , Boyett Mark R. , Hancox Jules. C. , Zhang Henggui
Published: November 2020

Marked age- and development- related differences have been observed in morphology and characteristics of action potentials (AP) of neonatal and adult sinoatrial node (SAN) cells. These may be attributable to a different set of ion channel interactions between the different ages. However, the underlying mechanism(s) have yet to be elucidated. The objective of this study was to determine the mechanisms underlying different spontaneous APs and heart rate between neonatal and adult SAN cells of the rabbit heart by biophysical modeling approaches. A mathematical model of neonatal rabbit SAN cells was developed by modifying the current densities and/or kinetics of ion channels and transporters in an adult cell model based on available experimental data obtained from neonatal SAN cells. The single cell models were then incorporated into a multi-cellular, two-dimensional model of the intact SAN-atrium to investigate the functional impact of altered ion channels during maturation on pacemaking electrical activities and their conduction at the tissue level. Effects of the neurotransmitter acetylcholine on the pacemaking activities in neonatal cells were also investigated and compared to those in the adult. Our results showed: (1) the differences in ion channel properties between neonatal and adult SAN cells are able to account for differences in their APs and the heart rate, providing mechanistic insight into understanding the reduced pacemaking rate of the rabbit sinoatrial node during postnatal development; (2) in the 2D model of the intact SAN-atria, it was shown that cellular changes during postnatal development impaired pacemaking activity through increasing the activation time and reducing the conduction velocity across the SAN; (3) the neonatal SAN model, with its faster beating rates, showed a greater sensitivity to parasympathetic modulation in response to acetylcholine than did the adult model. These results provide novel insights into the understanding of the cellular mechanisms underlying the differences in the cardiac pacemaking activities of the neonatal and adult SAN.
Association of Physical Fitness Performance Tests and Anthropometric Indices in Taiwanese Adults
Authors: Chen Po-Hung , Chen Wei , Wang Cheng-Wei , Yang Hui-Fei , Huang Wan-Ting , Huang Hsiu-Chen , Chou Che-Yi
Published: November 2020

Background

The association between physical fitness performance tests and anthropometric indices is not clear. The study aims to explore the association between physical fitness performance and anthropometric indices in Taiwanese community-dwelling adults. This may help in monitoring anthropometric indices to improve physical fitness.

Methods

We recruited 2216 participants aged 23–64 years between 2014 and 2017. Physical fitness performance, including abdominal muscular endurance (60-s sit-up test), flexibility (sit-and-reach test), and cardiorespiratory endurance (3-min step test), was evaluated in all participants. The association of the physical fitness performance and anthropometric indices, including body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR), was analyzed using linear regression, with adjustments for age and gender.

Results

Body mass index was negatively associated with abdominal muscular endurance (p < 0.001) and cardiorespiratory endurance (p < 0.001). Neither BMI, WC, WHR, nor WHtR were significantly associated with flexibility. Abdominal muscle endurance, flexibility, and cardiorespiratory endurance were significantly lower in obese participants when obesity was defined using a BMI of ≥27, 30, and 35 kg/m2. Participants with central obesity that was defined as WC ≥ 90 cm in men and 80 cm in women and WHtR ≥ 0.6 had lower abdominal muscular endurance than those without central obesity.

Conclusion

Body mass index is associated with abdominal muscular endurance and cardiorespiratory endurance in a reverse J-shaped manner. None of the anthropometric indices are significantly associated with flexibility. Obesity defined by BMI is linked to worse physical fitness performance and obesity defined using WHtR is linked to lower abdominal muscular endurance in Taiwanese community-dwelling adults.
Nicotiana benthamiana as a Transient Expression Host to Produce Auxin Analogs
Authors: Davis Katharine , Gkotsi Danai S. , Smith Duncan R. M. , Goss Rebecca J. M. , Caputi Lorenzo , O’Connor Sarah E.
Published: November 2020

Plant secondary metabolites have applications for the food, biofuel, and pharmaceutical industries. Recent advances in pathway elucidation and host expression systems now allow metabolic engineering of plant metabolic pathways to produce “new-to-nature” derivatives with novel biological activities, thereby amplifying the range of industrial uses for plant metabolites. Here we use a transient expression system in the model plantNicotiana benthamianato reconstitute the two-step plant-derived biosynthetic pathway for auxin (indole acetic acid) to achieve accumulation up to 500 ng/g fresh mass (FM). By expressing these plant-derived enzymes in combination with either bacterial halogenases and alternative substrates, we can produce both natural and new-to-nature halogenated auxin derivatives up to 990 ng/g FM. Proteins from the auxin synthesis pathway, tryptophan aminotransferases (TARs) and flavin-dependent monooxygenases (YUCs), could be transiently expressed in combination with four separate bacterial halogenases to generate halogenated auxin derivatives. Brominated auxin derivatives could also be observed after infiltration of the transfectedN. benthamianawith potassium bromide and the halogenases. Finally, the production of additional auxin derivatives could also be achieved by co-infiltration of TAR and YUC genes with various tryptophan analogs. Given the emerging importance of transient expression inN. benthamianafor industrial scale protein and product expression, this work provides insight into the capacity ofN. benthamianato interface bacterial genes and synthetic substrates to produce novel halogenated metabolites.
Identities Hidden in Challenges: The Sequential Mediation of Thriving at Work and Employee Investment
Authors: Saleem Sharjeel , Humayun Shazia , Latif Bilal , Iftikhar Umer , Sharif Imran
Published: November 2020

The present study explores the influence of challenge stressors on identity orientation directly and via thriving at work and employee investment. Drawing on the broaden–and–build theory of positive emotions, this study proposes challenge stressors as a critical predictor of identity orientation. The purpose of this article is to explore if a particular identity is salient in different contextual factors, and this study suggests that challenge stressors stimulate personal, relational, and collective identities to respond to a situation. The relationships hypothesized in this study were tested using a sample of 225 employees from the banking sector of Pakistan. A time-lagged research design consisting of two waves of data collection was employed. A structural equation modeling technique was used to test the hypotheses regarding the relationship between challenge stressors and identity orientation, including the role of thriving at work and employee investment as intervening mechanisms of this relationship. Results showed that challenge stressors had a significant positive relationship with identity orientation. The results also confirmed the sequential mediation of thriving at work and employee investment in the relationship between challenge stressors and identity orientation. The findings suggest that the positive side of stress as a strength motivates employees for continued self-development. Importantly, challenge stressors enhance employees’ ability to thrive at work and, in turn, they invest in the work more and identify themselves strongly with their organization and work.
Modulation of Repeated Anodal HD-tDCS on Attention in Healthy Young Adults
Authors: Lu Hongliang , Liu Quanhui , Guo Zhihua , Zhou Guangxin , Zhang Yajuan , Zhu Xia , Wu Shengjun
Published: November 2020

High-definition transcranial direct current stimulation (HD-tDCS) is a valid brain stimulation technology to optimize cognitive function. Recent evidence indicates that single anodal tDCS session enhances attention; however, the variation in attention produced by repeated anodal HD-tDCS over a longer period of time has not been explored. We examined the modulation of attention function in healthy young participants (39 young adults) who received repeated HD-tDCS sustained for 4 weeks. The results showed a robust benefit of anodal HD-tDCS on executive control and psychomotor efficiency, but not on orienting, alerting, or selective attention (inhibition); the benefit increased successively over 4 weeks; and the enhancement on executive control of each week was significant compared to baseline in the anodal group. In addition, the subjects’ performances on the test of executive control and psychomotor efficiency gradually restored to the initial level in the sham group, which appeared obviously from week 3 (after 9 interventions), but the improvement of attention in the anodal group was persistent. We conclude that repeated anodal HD-tDCS provides a positive benefit on executive control and psychomotor efficiency and has obvious accumulative effect after 9 or more times intervention compared to sham HD-tDCS. Additionally, our findings might provide pivotal guidance for the formulation of a strategy for the use of repeated anodal HD-tDCS to modulate on attention function.
Gender Difference in the Prevalence of Insomnia: A Meta-Analysis of Observational Studies
Authors: Zeng Liang-Nan , Zong Qian-Qian , Yang Yuan , Zhang Ling , Xiang Yi-Fan , Ng Chee H. , Chen Li-Gang , Xiang Yu-Tao
Published: November 2020

Objective: Insomnia is a major health challenge in the general population, but the results of the gender differences in the epidemiology of insomnia have been mixed. This is a meta-analysis to examine the gender difference in the prevalence of insomnia among the general population.

Methods:Two reviewers independently searched relevant publications in PubMed, EMBASE, PsycINFO, Web of Science from their inception to 16 April 2019. Studies that reported the gender-based prevalence of insomnia according to the international diagnostic criteria were included for analyses using the random-effects model.

Results:Eventually 13 articles were included in the meta-analysis. The pooled prevalence of insomnia in the general population was 22.0% [n = 22,980, 95% confidence interval (CI): 17.0–28.0%], and females had a significantly higher prevalence of insomnia compared with males (OR = 1.58, 95% CI: 1.35, 1.85, Z = 5.63, p < 0.0001). Subgroup analyses showed that greater gender difference was associated with the use of case-control study design and consecutive sampling method. Meta-regression analyses also revealed that higher proportion of females and better study quality were significantly associated with greater gender difference.

Conclusions:This meta-analysis found that the prevalence of insomnia in females was significantly higher than males in the included studies. Due to the negative effects of insomnia on health, regular screening, and effective interventions should be implemented in the general population particularly for females.
Feedlot Cattle Antimicrobial Use Surveillance Network: A Canadian Journey
Authors: Hannon Sherry J. , Brault Stephanie A. , Otto Simon J. G. , Morley Paul S. , McAllister Tim A. , Booker Calvin W. , Gow Sheryl P.
Published: November 2020

Antimicrobial drugs are important tools for maintaining human and animal health. Globally, antimicrobial use (AMU) in food-producing animals is under increasing scrutiny due to its potential to promote antimicrobial resistance (AMR). Historically, comprehensive Canadian data related to the types of antimicrobial drugs used, extent of use, common indicators of use and the demographics of the cattle populations receiving antimicrobial drugs have been limited, in part due to segmentation in the cattle industry and fragmentation of the drug distribution system. Appropriate AMU estimates are required to understand AMU practices, to interpret AMR levels and patterns, to meaningfully assess associated public health risks, and to inform stewardship activities. The Canadian beef cattle industry has a long history of collaboration in AMU and AMR research. Prior research projects identified both opportunities and challenges in the collection of AMU data. Cornerstone projects provided insight into the complexity of collecting AMU data in Canada's feedlot sector. This paper will discuss how the lessons learned from past work have contributed to the formation of a Canadian fed-cattle antimicrobial surveillance program that was initiated in 2019. This important surveillance program will allow feedlot cattle AMU to improve management decisions and support AMU best practices in the evolving Canadian AMR landscape.
Development of a Family of Jarratt-Like Sixth-Order Iterative Methods for Solving Nonlinear Systems with Their Basins of Attraction
Authors: Lee Min-Young , Kim Young Ik
Published: November 2020

We develop a family of three-step sixth order methods with generic weight functions employed in the second and third sub-steps for solving nonlinear systems. Theoretical and computational studies are of major concern for the convergence behavior with applications to special cases of rational weight functions. A number of numerical examples are illustrated to confirm the convergence behavior of local as well as global character of the proposed and existing methods viewed through the basins of attraction.
Herbicide-Based Weed Management for Soybean Production in the Far Eastern Region of Russia
Authors: Song Jong-Seok , Chung Ji-Hoon , Lee Kyu Jong , Kwon Jihyung , Kim Jin-Won , Im Ji-Hoon , Kim Do-Soon
Published: November 2020

This study was conducted to establish a weed management system based on the sequential application of pre-emergence (PRE) and post-emergence (POST) herbicides for soybean production in Primorsky krai. Field experiments were conducted for two years in a field located in Bogatyrka, Primorsky krai, Russia (N43°49′, E131°36′). No herbicide application resulted in significant soybean yield loss, 0.03–0.3 t ha−1, which is more than 91.6% yield loss compared with that of the weed-free plot. The PRE application of acetochlor showed good weed control efficacy (greater than 90% weed control) with acceptable soybean safety (less than 10% soybean damage), while the other PRE herbicides performed poorly in terms of weed control. The POST application of bentazon + acifluorfen, bentazon, and imazamox at 30 days after soybean sowing (DAS) showed good weed control efficacy with good soybean safety. Neither the PRE nor POST application alone showed a sufficient soybean yield protection, resulting in much lower soybean yield than the weed-free plot. The sequential application of acetochlor (PRE), followed by either bentazon + acifluorfen (POST) at 30 DAS in 2012 or bentazon + imazamox (POST) at 60 DAS in 2013 showed the best performance in soybean yields, 1.7 t and 1.9 t ha−1, respectively, provided with 724.5 US$ and 1155.6 US$ ha−1 of economic returns. For alternative PRE herbicides of acetochlor, which is now banned, our tests of the sequential application of S-metolachlor with other POST herbicides and the sole application of other PRE herbicides revealed that S-metolachlor and clomazone could also be considered. Our results thus demonstrate that the sequential applications of PRE and POST herbicides should be incorporated into the weed management system for soybean production in Primorsky krai, Russia.
Improved Prediction of Leaf Emergence for Efficacious Crop Protection: Assessing Field Variability in Phyllotherms for Upper Leaves in Winter Wheat and Winter Barley
Authors: El Jarroudi Moussa , Kouadio Louis , Junk Jürgen , Bock Clive H.
Published: November 2020

The choice of the phyllotherm value for predicting leaf emergence under field conditions is pivotal to the success of fungicide-based disease risk management in temperate cereals. In this study, we investigated phyllotherm variability for predicting the emergence of the three uppermost leaves (i.e., three last leaves to emerge) in winter wheat and winter barley fields. Data from four sites representative of wheat and barley growing regions in Luxembourg were used within the PROCULTURE model to predict the emergence of F-2, F-1 and F (F being the flag leaf) during the 2014–2019 cropping seasons. The phyllotherms tested ranged between 100 °Cd and 160 °Cd, in 15 °Cd steps, including the current default value of 130 °Cd. The comparisons between the observed and predicted emerged leaf area were qualitatively evaluated using the mean absolute error (MAE), the root mean square error (RMSE) and Willmott’s index (WI). A phyllotherm of 100 °Cd accurately and reliably predicted the emergence of all three upper leaves under the various environmental conditions and crop cultivars of winter wheat and winter barley over the study period. MAE and RMSE were generally <5% and the WI values were most often ≥0.90 for F-1 and F. For phyllotherm values ≥115 °Cd, the prediction errors generally increased for F-1 and F, with MAE and RMSE exceeding 20% in most cases. F-2 agreement between observed and predicted values was generally similar when using 100 °Cd or 115 °Cd. These results tie in valuable, complementary information regarding the variability of phyllotherms within leaf layers in winter wheat and winter barley in Luxembourg. Accurate and reliable leaf emergence prediction from F-2 to F allows for timely fungicide application, which ensures lasting protection against infections by foliar fungal disease pathogens. Hence, understanding phyllotherms can help ensure timely, environmentally sound, and efficacious fungicide application while increasing the likelihood of improved yields of winter wheat and winter barley.
The Regulatory Role of Apelin on the Appetite and Growth of Common Carp (Cyprinus Carpio L.)
Authors: Yan Xiao , Qin Chaobin , Yang Guokun , Deng Dapeng , Yang Liping , Feng Junchang , Mi Jiali , Nie Guoxing
Published: November 2020

Apelin, a kind of active polypeptide, has many biological functions, such as promoting food intake, enhancing immunity, and regulating energy balance. In mammals, studies have indicated that apelin is involved in regulating food intake. However, there are relatively few studies about the regulatory effect of apelin on fish feeding, and the specific mechanism is not clear. Therefore, the purpose of this study was to preliminarily investigate the regulatory effects of apelin on key genes of feeding and growth in common carp (Cyprinus Carpio L.) through in vitro and in vivo experiments. In the present study, after incubation with different concentrations of Pyr-apelin-13 (0, 10, 100, and 1000 nM) in hypothalamic fragments, the expressions of Neuropeptide Y (NPY) and Agouti related peptide (AgRP) mRNA were significantly up-regulated at 12 and 3 h, respectively, and the significant down-regulation of Cocaine and amphetamine-related transcript (CART) mRNA expression was observed at 1 and 3 h. In vivo, after Pyr-apelin-13 oral administration (0, 1, 10, and 100 pmol/g), the orexin mRNA level in the hypothalamus of common carp was significantly increased at 1, 6, and 12 h, while CART/(Proopiomelanocortin) POMC mRNA levels in the hypothalamus of common carp were significantly down-regulated. Following incubation with different concentrations of Pyr-apelin-13 (0, 10, 100, and 1000 nM) in primary hepatocytes, GHR (Growth hormone receptor), IGF2 (Insulin-like growth factor 2), IGFBP2 (Insulin like growth factor binding protein 2), and IGFBP3 (Insulin like growth factor binding protein 3) mRNA levels were significantly increased at 3 h. In vivo, the levels of IGF1 (Insulin-like growth factor 1), IGF2, IGFBP2 (Insulin like growth factor binding protein 2), and IGFBP3 mRNA were significantly increased after the oral administration of Pyr-apelin-13 in the hepatopancreas, in a time and dose-dependent manner. These results support the hypothesis that Pyr-apelin-13 might regulate the feeding and growth of common carp through mediating the expressions of appetite- and growth-related genes. Overall, apelin, which is an orexigenic peptide, improves food intake and is involved in the growth of common carp.
Therapeutic Potential of Heme Oxygenase-1 and Carbon Monoxide in Acute Organ Injury, Critical Illness, and Inflammatory Disorders
Authors: Ryter Stefan
Published: November 2020

Heme oxygenase-1 (HO-1) is an inducible stress protein that catalyzes the oxidative conversion of heme to carbon monoxide (CO), iron, and biliverdin (BV), the latter of which is converted to bilirubin (BR) by biliverdin reductase. HO-1 has been implicated as a cytoprotectant in various models of acute organ injury and disease (i.e., lung, kidney, heart, liver). Thus, HO-1 may serve as a general therapeutic target in inflammatory diseases. HO-1 may function as a pleiotropic modulator of inflammatory signaling, via the removal of heme, and generation of its enzymatic degradation-products. Iron release from HO activity may exert pro-inflammatory effects unless sequestered, whereas BV/BR have well-established antioxidant properties. CO, derived from HO activity, has been identified as an endogenous mediator that can influence mitochondrial function and/or cellular signal transduction programs which culminate in the regulation of apoptosis, cellular proliferation, and inflammation. Much research has focused on the application of low concentration CO, whether administered in gaseous form by inhalation, or via the use of CO-releasing molecules (CORMs), for therapeutic benefit in disease. The development of novel CORMs for their translational potential remains an active area of investigation. Evidence has accumulated for therapeutic effects of both CO and CORMs in diseases associated with critical care, including acute lung injury/acute respiratory distress syndrome (ALI/ARDS), mechanical ventilation-induced lung injury, pneumonias, and sepsis. The therapeutic benefits of CO may extend to other diseases involving aberrant inflammatory processes such as transplant-associated ischemia/reperfusion injury and chronic graft rejection, and metabolic diseases. Current and planned clinical trials explore the therapeutic benefit of CO in ARDS and other lung diseases.
Evolution Characteristics of Separated Vortices and Near-Wall Flow in a Centrifugal Impeller in an Off-Designed Condition
Authors: Zhou Shihao , Lin Peifeng , Zhang Wei , Zhu Zuchao
Published: November 2020

Flow separation is undesirable and lowers the efficiency of centrifugal impellers. In this study, the evolution characteristics of separated vortices in a centrifugal impeller are studied under the off-designed flow rate condition. Unsteady Reynolds-Averaged Navier–Stokes (URANS) with standard k-ε turbulent model is applied to simulate the alternating stall in the six-blade centrifugal impeller. We present and analyze the distributions of pressure gradient (either adverse or favorable) and skin friction coefficients on both sides of the blade for the stalled and unstalled passages to study the relationship between pressure gradient and separation of boundary layer flow. The evolution of skin friction coefficient is also presented at various axial cross sections. Numerical results reveal that, for the stalled passage, the increase in adverse pressure gradient on the pressure surface near the middle of the blade (S/S0 = 0.4) is much larger than that of the suction surface during a vortex formation cycle. The skin friction coefficient on the pressure surface also increases in magnitude sharply and the variation shows a peak-valley trend, while the coefficient on the suction surface increases slowly. Comparing the distribution of skin friction coefficient on the pressure surface of the same blade at different axial cross sections, it is found that the skin friction coefficient notably increases at S/S0 = 0.6 on the middle axial cross section (Z/b2 = 0.5). For the unstalled passage, both the pressure and suction surfaces produce favorable pressure gradients. The skin friction coefficient on the pressure surface shows an increasing trend around S/S0 = 0.5, and a large vortex can be seen at the exit of the impeller. The variation of skin friction coefficient on the suction surface is relatively mild; thus, the flow is relatively stable. It is clarified that the effect of adverse pressure gradient and wall shear stress jointly cause separation of the boundary layer; thus, the separated vortices are generated in the rotating impeller and deteriorate the performance of the impeller.
Non-Destructive Testing of Aircraft Structures Using Microwire-Based Tensile Stress Sensor
Authors: Šmelko Miroslav , Draganová Katarína , Lipovský Pavol , Semrád Karol , Blišťanová Monika , Kašper Patrik
Published: November 2020

The development of non-destructive methods for material testing and diagnostics has been, in the last few decades, focused mainly on optical, infrared, thermography, ultrasonic, acoustic or X-ray principles. This article deals with the possibility of adaptation of magnetic sensors for the diagnostics of aircraft structures. The developed sensors are based on the enhanced induction method, allowing contactless diagnostics of the material structure. In the role of the sensing element, amorphous magnetic microwires were used. Thanks to their dimensions, microwires can either be placed on the material surface or be embedded directly into the composite material without structural violations. In the article, the measurement principles of the developed microwire-based tensile stress sensors, together with the experimental measurements with the sensors originally tested in the aircraft wing, are presented.
Burst Detection in Water Distribution Systems: The Issue of Dataset Collection
Authors: Menapace Andrea , Zanfei Ariele , Felicetti Manuel , Avesani Diego , Righetti Maurizio , Gargano Rudy
Published: November 2020

Developing data-driven models for bursts detection is currently a demanding challenge for efficient and sustainable management of water supply systems. The main limit in the progress of these models lies in the large amount of accurate data required. The aim is to present a methodology for the generation of reliable data, which are fundamental to train anomaly detection models and set alarms. Thus, the results of the proposed methodology is to provide suitable water consumption data. The presented procedure consists of stochastic modelling of water request and hydraulic pipes bursts simulation to yield suitable synthetic time series of flow rates, for instance, inlet flows of district metered areas and small water supply systems. The water request is obtained through the superimposition of different components, such as the daily, the weekly, and the yearly trends jointly with a random normal distributed component based on the consumption mean and variance, and the number of users aggregation. The resulting request is implemented into the hydraulic model of the distribution system, also embedding background leaks and bursts using a pressure-driven approach with both concentrated and distributed demand schemes. This work seeks to close the gap in the field of synthetic generation of drinking water consumption data, by establishing a proper dedicated methodology that aims to support future water smart grids.
Numerical Analysis of EOD Helmet under Blast Load Events Using Human Head Model
Authors: Valverde-Marcos Borja , Rubio Ignacio , Antona-Makoshi Jacobo , Chawla Anoop , Loya José Antonio , Rodríguez-Millán Marcos
Published: November 2020

Brain injury resulting from improved explosives devices (IEDs) is identified as a challenge for force securities to improve protection equipment. This paper focuses on the mechanical response of explosive ordnance disposal (EOD) helmet under different blast loadings. Limited published studies on this type of helmet are available in the scientific literature. The results obtained show the blast performance of the EOD helmet because a decrease in the maximum values in the measured damage parameters is found. Therefore, an EOD helmet minimizes the risks of the severity of injuries on the user showing a low probability of injury.
A Proposed Extended Version of the Hadi-Vencheh Model to Improve Multiple-Criteria ABC Inventory Classification
Authors: Lin Pei-Chun , Chang Hung-Chieh
Published: November 2020

The ABC classification problem is approached as a ranking problem by the most current classification models; that is, a group of inventory items is expressed according to its overall weighted score of criteria in descending order. In this paper, we present an extended version of the Hadi-Vencheh model for multiple-criteria ABC inventory classification. The proposed model is one based on the nonlinear weighted product method (WPM), which determines a common set of weights for all items. Our proposed nonlinear WPM incorporates multiple criteria with different measured units without converting the performance of each inventory item, in terms of converting each criterion into a normalized attribute value, thereby providing an improvement over the model proposed by Hadi-Vencheh. Our study mainly includes various criteria for ABC classification and demonstrates an efficient algorithm for solving nonlinear programming problems, in which the feasible solution set does not have to be convex. The algorithm presented in this study substantially improves the solution efficiency of the canonical coordinates method (CCM) algorithm when applied to large-scale, nonlinear programming problems. The modified algorithm was tested to compare our proposed model results to the results derived using the Hadi-Vencheh model and demonstrate the algorithm’s efficacy. The practical objectives of the study were to develop an efficient nonlinear optimization solver by optimizing the quality of existing solutions, thus improving time and space efficiency.
Exploring the Capabilities of Scanning Microwave Microscopy to Characterize Semiconducting Polymers
Authors: Douhéret Olivier , Théron Didier , Moerman David
Published: November 2020

Standing at the meeting between solid state physics and optical spectroscopy, microwave characterization methods are efficient methods to probe electronic mechanisms and mesoscopic transport in semiconducting polymers. Scanning microwave microscopy, augmented with a Mach-Zehnder interferometer detection unit to allow for the probing of high impedance structures was applied on poly(3-hexylthiophene-2,5-diy) and exhibited high sensitivity while operating at the nanoscale. Provided a well-defined experiment protocol, S11 phase and amplitude signals are shown to lead simultaneously yet independently to probing the variations of the dielectric properties in the materials, i.e., conductive and capacitive properties, respectively, upon applied DC gate bias. Adjusting the operating microwave frequency can also serve to probe carrier trapping mechanisms.
Performance Analysis and Comparison of Two Base Isolation Systems with Super-Large Displacement Friction Pendulum Bearings
Authors: Wu Peisong , Ou Jinping
Published: November 2020

Isolation technology has been successfully applied in seismic migration. With increasing of seismic demand, seismic performance of isolation structures subjected to very-rare earthquakes need further improvement. However, the isolation layer generally lacks sufficient deformation ability under very-rare earthquakes due to the deformation limit of classical isolation bearing. In order to circumvent the difficulty, this paper develops two new isolation bearings, namely super-large displacement rotation friction pendulum bearing (SLDRFPB) and super-large displacement translation friction pendulum bearing (SLDTFPB). By setting spherical shells with large span and large radius, large horizontal displacement and small horizontal stiffness can be achieved. Safety of the isolation layer and the isolation effect of the superstructure can be greatly improved. SLDTFPB differs from SLDRFPB in the motion state of the superstructure and space utilization of the isolation layer, thus SLDRFPB and SLDTFPB are suitable for structures with different requirements. Due to rotation of the superstructure with SLDRFPB or sliding frames in SLDTFPB, the traditional design method of friction pendulum bearing is no longer suitable. We present a new procedure to accurately and conveniently evaluate seismic performance of two developed bearings. Numerical simulation shows that the seismic response of both the superstructure and isolation layer is small. Developed SLDRFPB and SLDTFPB have sufficient emergency capacity and isolation resilience when subjected to very-rare earthquakes.
An Efficient Approach for Identification of the Inlet Distortion of Engine Based on Acoustic Emission Technique
Authors: Huang Jiaoyan , Xia Aiguo , Zou Shenao , Han Cong , Yang Guoan
Published: November 2020

Effective and accurate diagnosis of engine health is key to ensuring the safe operation of engines. Inlet distortion is due to the flow or the pressure variations. In the paper, an acoustic emission (AE) online monitoring technique, which has a faster response time compared with the ordinary vibration monitoring technique, is used to study the inlet distortion of an engine. The results show that with the deterioration of the inlet distortion, the characteristic parameters of AE signals clearly evolve in three stages. Stage I: when the inlet distortion J ≤ 30%, the characteristic parameters of the AE signal increase as J increases and the amplitude saturates at J = 23%, faster than the other three parameters (the strength, the root mean square (RMS), and the average signal level (ASL)). Stage II: when the inlet distortion 30% < J ≤ 43.64%, all the parameters saturate with only slight fluctuations as J increases and the engine works in an unstable statue. Stage III: when the inlet distortion J > 43.64%, the engine is prone to surge. Furthermore, an intelligent recognition method of the engine inlet distortion based on a unit parameter entropy and the back propagation (BP) neural network is constructed. The recognition accuracy is as high as 97.5%, and this method provides a new approach for engine health management.
Study on the Applicability of Dynamic Stability Evaluation Criteria by Comparison of Trackside Measurement Results of Different Track Structures
Authors: Oh Kyuhwan , Lee Jaeik , Choi Junhyeok , Park Yonggul
Published: November 2020

Countries such as Korea adopt design codes, evaluation criteria and specifications from standards originating abroad; this leads to a lack of distinction of the separate applications of dynamic stability evaluation parameters between various track structures of different track moduli. This paper discusses the applicability of the dynamic stability evaluation method of railway track structures by assessing 10 different types of railway track sections of a newly constructed railway operation line (5 ballasted and 5 concrete type track structures) by field instrumentation testing. Parameters of track support stiffness (TSS), wheel load fluctuation, derailment coefficient, and rail displacement are measured. The respective results are first compared to the standard criteria (design specification) and comparisons between the different track types are presented as ratios. Findings show that while all of the tracks satisfy the design specification requirements, each track type measurement result varies by a noticeable degree, particularly when comparing between concrete and ballast type track structures. Results of the study demonstrate that using the same dynamic stability evaluation criteria can lead to an incorrect assessment of the track performance evaluation of track structure, and a separate evaluation parameter for ballasted and concrete track structures is required.
Business Continuity Plan in the Higher Education Industry: University Students’ Perceptions of the Effectiveness of Academic Continuity Plans during Covid-19 Pandemic
Authors: Rasiah Ratneswary , Kaur Harpaljit , Guptan Vinitha
Published: November 2020

The Covid-19 pandemic is one of the most disruptive, life-changing events that had brought the world to a perpetual standstill in 2020. Schools and institutions of higher education were impacted badly, resulting from the lockdowns and movement restrictions imposed by the governments of numerous countries. Students and faculty found themselves in virtual classrooms, with many caught unaware of what they needed to do, having to learn new things at lightning speed and feeling a sense of despair. While many online learners had frustrations and concerns regarding their online learning experience, there were those who had a good learning experience. The students’ observations and perceptions of the difficulties and opportunities they encountered in their online learning experience were assessed through grounded theory using textual thematic qualitative analysis of their reflective feedback. The findings reveal that most students had a good online learning experience and found that the academic continuity plans implemented by the universities were effective. The concerns that some students had with online learning were related to technological drawbacks such as poor internet connections, and personal concerns about academic ability and time management skills, among others. This study concludes by offering insights and recommendations to institutions, faculty, and students on how best to conduct online learning and teaching for all.
Optimization by Central Composite Experimental Design of the Synthesis of Physically Crosslinked Chitosan Spheres
Authors: Zamora Lagos Sara Isabel , Murillo Salas Jefferson , Valencia Zapata Mayra Eliana , Mina Hernández José Herminsul , Grande Tovar Carlos David
Published: November 2020

Chitosan (CS) has special properties such as biocompatibility, biodegradability, antibacterial, and biological activity which make this material is currently studied in various applications, including tissue engineering. There are different methods to modify the morphology of CS. Most use chemical crosslinking agents, however, those methods have disadvantages such as low polymer degradability and unwanted side effects. The objective of this research was to obtain CS spheres through the physical crosslinking of commercial CS without using crosslinking agents through a simple coacervation method. A central composite experimental design was used to optimize the synthesis of the CS spheres and by the response surface methodology it was possible to obtain CS spheres with the smallest diameter and the most regular morphology. With the optimal formulation (CS solution 1.8% (w/v), acetic acid (AAC) solution 1% (w/v), sodium hydroxide (NaOH) solution 13% (w/v), relative humidity of (10%) and needle diameter of 0.6 mm), a final sphere diameter of 1 mm was obtained. Spheres were characterized by physical, chemical, thermal, and biological properties in simulated body fluid (SBF). The results obtained allowed us to understand the effect of the studied variables on the spheres’ diameter. An optimized condition facilitated the change in the morphology of the CS while maintaining its desirable properties for use in tissue engineering.
Recent Advances in MXene Nanocomposite-Based Biosensors
Authors: Yoon Jinho , Shin Minkyu , Lim Joungpyo , Lee Ji-Young , Choi Jeong-Woo
Published: November 2020

The development of advanced biosensors with high sensitivity and selectivity is one of the most demanded concerns in the field of biosensors. To meet this requirement, up until now, numerous nanomaterials have been introduced to develop biosensors for achieving high sensitivity and selectivity. Among the latest nanomaterials attracting attention, MXene is one of the best materials for the development of biosensors because of its various superior properties. MXenes are two-dimensional inorganic compounds with few atomic layers that possess excellent characteristics including high conductivity and superior fluorescent, optical, and plasmonic properties. In this review, advanced biosensors developed on the basis of the MXene nanocomposite are discussed with the selective overview of recently reported studies. For this, introduction of the MXene including the definition, synthesis methods, and its properties are discussed. Next, MXene-based electrochemical biosensors and MXene-based fluorescent/optical biosensors are provided, which are developed on the basis of the exceptional properties of the MXene nanocomposite. This review will suggest the direction for use of the Mxene nanocomposite to develop advanced biosensors with high sensitivity and selectivity.
Avenanthramide C Prevents Neuronal Apoptosis via PI3K/Akt/GSK3β Signaling Pathway Following Middle Cerebral Artery Occlusion
Authors: Jin Baoyuan , Kim Hyehyun , Choi Jeong-Il , Bae Hong-Beom , Jeong Seongtae
Published: November 2020

Avenanthramides are a group of phenolic alkaloids that have been shown to have anti-inflammatory, anti-oxidant, anti-atherogenic, and vasodilation effects. The aim of the present study was to investigate the neuroprotective effect of avenanthramide-c (Avn-c) in focal brain ischemia and reperfusion injury using middle cerebral artery occlusion (MCAo) model with mice. Male C57BL/6 mice were divided into 4 groups: sham, control (MCAo), Avn-c, and Avn-c + LY294002 (phosphoinositide 3-kinase inhibitor) group. They were subjected to 60 min MCAo followed by reperfusion. Brain infarct volume and neurological deficit scores were measured after 24 h of reperfusion. We evaluated the blood brain barrier (BBB) integrity (ZO-1, VE-cadherin and occludin) and apoptosis (Bax, Bcl2, caspase3, Cytochrome C, and poly ADP ribose polymerase(PARP)-1). We also measured GSK3β for evaluation of the downstream mechanism of Akt. We examined the effect of the Avn-c in the phosphoinositide 3-kinase pathway. Avn-c reduced neurological score and infarction size. Avn-c inhibited the MCAo-induced disruption of tight junction proteins. Avn-c decreased apoptotic protein expression (Bax, Cytochrome C, and cleaved PARP-1) and increased anti-apoptotic protein expression (Bcl2) after MCAo. Akt and GSK3β were decreased in MCAo group and were restored in Avn-c group. This effect of Avn-c was abolished by PI3K inhibitor. In summary, Avn-c showed neuroprotective effects through PI3K-Akt-GSK3β signaling pathway.