bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in Spinal-Reflex Excitability during Static Stretch and/or Explosive Contraction
Authors: Min Kyeong Eun , Lee YongSuk , Park Jihong
Published: March 2021

To examine individual or combined effects of static stretch and explosive contraction on quadriceps spinal-reflex excitability (the peak Hoffmann’s reflex normalized by the peak motor-response) and the latency times of the Hoffmann’s reflex and motor-response. Fourteen healthy young males randomly experienced four conditions (stretch, contraction, stretch + contraction, and control—no intervention). For the stretch condition, three sets of a 30 s hold using the modified Thomas test on each leg were performed. For the contraction condition, three trials of maximal countermovement vertical jump were performed. Quadriceps spinal-reflex excitability and the latent period of each value on the right leg were compared at pre- and post-condition. All measurement values across conditions were not changed at any time point (condition × time) in spinal-reflex excitability (F6,143 = 1.10, p = 0.36), Hoffmann’s reflex latency (F6,143 = 0.45, p = 0.84), motor-response latency (F6,143 = 0.37, p = 0.90), and vertical jump heights (F2,65 = 1.82, p = 0.17). A statistical trend was observed in the contraction condition that spinal-reflex excitability was increased by 42% (effect size: 0.63). Neither static stretch nor explosive contraction changed the quadriceps spinal-reflex excitability, latency of Hoffmann’s reflex, and motor-response. Since our stretch protocol did not affect jumping performance and our contraction protocol induced the post-activation potentiation effect, either protocol could be used as pre-exercise activity.
Mechanical Properties of White Metal on SCM440 Alloy Steel by Laser Cladding Treatment
Authors: Jeong Jae-Il , Kim Jong-Hyoung , Choi Si-Geun , Cho Young Tae , Kim Chan-Kyu , Lee Ho
Published: March 2021

The bearing is a machine element that plays an important role in rotating the shaft of a machine while supporting its weight and load. Numerous bearings have been developed to improve durability and life, depending on the functions and operating conditions in which they are desired. White metal is one of method to improve durability that is soft and bonded to the inner surface of the bearing to protect the bearing shaft. Currently, the centrifugal casting process is used as a white metal lamination method, but it involves problems such as long processing times, high defect rates and harmful health effects. In this paper, a laser cladding treatment is applied to bond powdered white metal to SCM440 alloy steel, which is used as bearing material in terms of replacing the risks of a centrifugal process. In order to understand whether laser cladding is a suitable process, this paper compares the mechanical properties of white metal produced on SCM440 alloy steel by centrifugal casting and the laser cladding process. The laser power, powder feed rate and laser head speed factors are varied to understand the mechanical properties and measure the hardness using micro Vickers and conduct field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and friction testing to understand the mechanical properties and surface characteristics. Based on the results, the hardness values of the cladding (white metal) layer ranged between 24 and 26 HV in both the centrifugal casting and laser cladding methods. However, the hardness of the white metal produced by laser cladding at about a depth of 0.1 mm rose rapidly in the cladding process, forming a heat-affected zone (HAZ) with an average hardness value of 200 HV at a laser power of 1.1 kW, 325 HV at 1.3 kW and 430 HV at 1.5 kW. The surface friction testing results revealed no significant differences in the friction coefficient between the centrifugal casting and laser cladding methods, which allows the assumption that the processing method does not significantly influence the friction coefficient.
Lower-Extremity Intra-Joint Coordination and Its Variability between Fallers and Non-Fallers during Gait
Authors: Sadeghi Hassan , Shojaedin Seyed Sadredin , Abbasi Ali , Alijanpour Elham , Vieira Marcus Fraga , Svoboda Zdeněk , Nazarpour Kianoush
Published: March 2021

Falling is one of the most common causes of hip fracture and death in older adults. A comparison of the biomechanics of the gait in fallers and non-fallers older adults, especially joint coordination and coordination variability, enables the understanding of mechanisms that underpin falling. Therefore, we compared lower-extremity intra-joint coordination and its variability between fallers and non-fallers older adults during gait. A total of 26 older adults, comprising 13 fallers, took part in this study. The participants walked barefoot at a self-selected speed on a 10-m walkway. Gait kinematics in the dominant leg during 10 cycles were captured with 10 motion tracking cameras at a sampling rate of 100 Hz. Spatiotemporal gait parameters, namely, cadence, walking speed, double support time, stride time, width, and length, as well as intra-joint coordination and coordination variability in the sagittal plane were compared between the two groups. Results showed that fallers walked with significant lower cadence, walking speed, and stride length but greater double support and stride time than non-fallers. Significant differences in the ankle-to-knee, knee-to-hip, and ankle-to-hip coordination patterns between fallers and non-fallers and less coordination variability in fallers compared to non-fallers in some instants of the gait cycles were observed. The differences in spatiotemporal gait parameters in fallers compared to non-fallers may indicate an adaptation resulting from decreased efficiency to decrease the risk of falling. Moreover, the differences in segment coordination and its variability may indicate an inconsistency in neuromuscular control. It may also indicate reduced ability to control the motion of the leg in preparation for foot contact with the ground and the knee and ankle motions during loading response. Finally, such differences may show less control in generating power during the push-off phase in fallers.
Structural Biology and Structure–Function Relationships of Membrane Proteins
Authors: Moraes Isabel , Quigley Andrew
Published: March 2021

To understand the biological complexity of life, one needs to investigate how biomolecules behave and interact with each other at a molecular level [...]
Small Ruminants and Its Use in Regenerative Medicine: Recent Works and Future Perspectives
Authors: Alvites Rui Damásio , Branquinho Mariana Vieira , Sousa Ana Catarina , Lopes Bruna , Sousa Patrícia , Mendonça Carla , Atayde Luís Miguel , Maurício Ana Colette
Published: March 2021

Medical and translational scientific research requires the use of animal models as an initial approach to the study of new therapies and treatments, but when the objective is an exploration of translational potentialities, classical models fail to adequately mimic problems in humans. Among the larger animal models that have been explored more intensely in recent decades, small ruminants, namely sheep and goats, have emerged as excellent options. The main advantages associated to the use of these animals in research works are related to their anatomy and dimensions, larger than conventional laboratory animals, but very similar to those of humans in most physiological systems, in addition to their low maintenance and feeding costs, tendency to be docile, long life expectancies and few ethical complications raised in society. The most obvious disadvantages are the significant differences in some systems such as the gastrointestinal, and the reduced amount of data that limits the comparison between works and the validation of the characterization essays. Despite everything, recently these species have been increasingly used as animal models for diseases in different systems, and the results obtained open doors for their more frequent and advantageous use in the future. The purpose of this review is to summarize the general principles related to the use of small ruminants as animal models, with a focus on regenerative medicine, to group the most relevant works and results published recently and to highlight the potentials for the near future in medical research.
Dilignans with a Chromanol Motif Discovered by Molecular Networking from the Stem Barks of Magnolia obovata and Their Proprotein Convertase Subtilisin/Kexin Type 9 Expression Inhibitory Activity
Authors: Ahn Jongmin , Chae Hee-Sung , Pel Pisey , Kim Young-Mi , Choi Young Hee , Kim Jinwoong , Chin Young-Won
Published: March 2021

Natural products have been fundamental materials in drug discovery. Traditional strategies for observing natural products with novel structure and/or biological activity are challenging due to large cost and time consumption. Implementation of the MS/MS-based molecular networking strategy with the in silico annotation tool is expected to expedite the dereplication of secondary metabolites. In this study, using this tool, two new dilignans with a 2-phenyl-3-chromanol motif, obovatolins A (1) and B (2), were discovered from the stem barks of Magnolia obovata Thunb. along with six known compounds (3–8), expanding chemical diversity of lignan skeletons in this natural source. Their structures and configurations were elucidated using spectroscopic data. All isolates were evaluated for their PCSK9 mRNA expression inhibitory activity. Obovatolins A (1) and B (2), and magnolol (3) showed potent lipid controlling activities. To identify transcriptionally controlled genes by 1 along with downregulation of PCSK9, using small set of genes (42 genes) related to lipid metabolism selected from the database, focused bioinformatic analysis was carried out. As a result, it showed the correlations between gene expression under presence of 1, which led to detailed insight of the lipid metabolism caused by 1.
Differential MicroRNA Expression Involved in Endometrial Receptivity of Goats
Authors: Zang Xupeng , Zhou Chen , Wang Wenjing , Gan Jianyu , Li Yaokun , Liu Dewu , Liu Guangbin , Hong Linjun
Published: March 2021

Endometrial receptivity represents one of the leading factors affecting the successful implantation of embryos during early pregnancy. However, the mechanism of microRNAs (miRNAs) to establish goat endometrial receptivity remains unclear. This study was intended to identify potential miRNAs and regulatory mechanisms associated with establishing endometrial receptivity through integrating bioinformatics analysis and experimental verification. MiRNA expression profiles were obtained by high-throughput sequencing, resulting in the detection of 33 differentially expressed miRNAs (DEMs), followed by their validation through quantitative RT-PCR. Furthermore, 10 potential transcription factors (TFs) and 1316 target genes of these DEMs were obtained, and the TF–miRNA and miRNA–mRNA interaction networks were constructed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that these miRNAs were significantly linked to establishing endometrial receptivity. Moreover, the fluorescence in situ hybridization (FISH) analysis, dual-luciferase report assay, and immunohistochemistry (IHC) analysis corroborated that chi-miR-483 could directly bind to deltex E3 ubiquitin ligase 3L (DTX3L) to reduce its expression level. In conclusion, our findings contribute to a better understanding of molecular mechanisms regulating the endometrial receptivity of goats, and they provide a reference for improving embryo implantation efficiency.
In Vitro Preformed Biofilms of Bacillus safensis Inhibit the Adhesion and Subsequent Development of Listeria monocytogenes on Stainless-Steel Surfaces
Authors: Hascoët Anne-Sophie , Ripolles-Avila Carolina , Cervantes-Huamán Brayan R. H. , Rodríguez-Jerez José Juan
Published: March 2021

Listeria monocytogenes continues to be one of the most important public health challenges for the meat sector. Many attempts have been made to establish the most efficient cleaning and disinfection protocols, but there is still the need for the sector to develop plans with different lines of action. In this regard, an interesting strategy could be based on the control of this type of foodborne pathogen through the resident microbiota naturally established on the surfaces. A potential inhibitor, Bacillus safensis, was found in a previous study that screened the interaction between the resident microbiota and L. monocytogenes in an Iberian pig processing plant. The aim of the present study was to evaluate the effect of preformed biofilms of Bacillus safensis on the adhesion and implantation of 22 strains of L. monocytogenes. Mature preformed B. safensis biofilms can inhibit adhesion and the biofilm formation of multiple L. monocytogenes strains, eliminating the pathogen by a currently unidentified mechanism. Due to the non-enterotoxigenic properties of B. safensis, its presence on certain meat industry surfaces should be favored and it could represent a new way to fight against the persistence of L. monocytogenes in accordance with other bacterial inhibitors and hygiene operations.
MicroRNAs as Predictive Biomarkers of Resistance to Targeted Therapies in Gastrointestinal Tumors
Authors: Angerilli Valentina , Galuppini Francesca , Businello Gianluca , Dal Santo Luca , Savarino Edoardo , Realdon Stefano , Guzzardo Vincenza , Nicolè Lorenzo , Lazzarin Vanni , Lonardi Sara , Loupakis Fotios , Fassan Matteo
Published: March 2021

The advent of precision therapies against specific gene alterations characterizing different neoplasms is revolutionizing the oncology field, opening novel treatment scenarios. However, the onset of resistance mechanisms put in place by the tumor is increasingly emerging, making the use of these drugs ineffective over time. Therefore, the search for indicators that can monitor the development of resistance mechanisms and above all ways to overcome it, is increasingly important. In this scenario, microRNAs are ideal candidate biomarkers, being crucial post-transcriptional regulators of gene expression with a well-known role in mediating mechanisms of drug resistance. Moreover, as microRNAs are stable molecules, easily detectable in tissues and biofluids, they are the ideal candidate biomarker to identify patients with primary resistance to a specific targeted therapy and those who have developed acquired resistance. The aim of this review is to summarize the major studies that have investigated the role of microRNAs as mediators of resistance to targeted therapies currently in use in gastro-intestinal neoplasms, namely anti-EGFR, anti-HER2 and anti-VEGF antibodies, small-molecule tyrosine kinase inhibitors and immune checkpoint inhibitors. For every microRNA and microRNA signature analyzed, the putative mechanisms underlying drug resistance were outlined and the potential to be translated in clinical practice was evaluated.
Perspectives on Epigenetics and Cancer Immunotherapy: A Preface to Special Issue
Authors: Alvarez-Errico Damiana
Published: March 2021

The interaction of tumor cells with immune cells within the tumor microenvironment (TME) is the basis for several strategies of tumor evasion from immune surveillance, which nurture cancer development [...]
Synthesis of Magnetic α-Fe2O3/Rutile TiO2 Hollow Spheres for Visible-Light Photocatalytic Activity
Authors: Zhou Zhongli , Yin Hang , Zhao Yuling , Zhang Jianmin , Li Yahui , Yuan Jinshi , Tang Jie , Wang Fengyun
Published: March 2021

The high recombination rate of the electron-hole pair on the surface of rutile TiO2 (RT) reduces its photocatalytic performance, although it has high thermodynamic stability and few internal grain defects. Therefore, it is necessary for RT to develop effective methods to reduce electron-hole pair recombination. In this study, magnetic α-Fe2O3/Rutile TiO2 self-assembled hollow spheres were fabricated via a facile hydrothermal reaction and template-free method. Based on the experimental result, phosphate concentration was found to play a crucial role in controlling the shape of these hollow α-Fe2O3/RT nanospheres, and the optimal concentration is 0.025 mM. Due to a heterojunction between α-Fe2O3 and RT, the electron-hole pair recombination rate was reduced, the as-synthesized hollow α-Fe2O3/RT nanospheres exhibited excellent photocatalysis in rhodamine B (RhB) photodegradation compared to α-Fe2O3 and RT under visible-light irradiation, and the degradation rate was about 16% (RT), 60% (α-Fe2O3), and 93% (α-Fe2O3/RT) after 100 min. Moreover, α-Fe2O3/RT showed paramagnetism and can be recycled to avoid secondary environmental pollution.
Photocatalytic Degradation of Polycyclic Aromatic Hydrocarbons in Fine Particulate Matter (PM2.5) Collected on TiO2-Supporting Quartz Fibre Filters
Authors: Sohara Koki , Yamauchi Katsuya , Sun Xu , Misawa Kazuhiro , Sekine Yoshika
Published: March 2021

Airborne fine particulate matter (PM2.5) pollution is known to have adverse effects on human health, and owing to their carcinogenic and mutagenic nature, polycyclic aromatic hydrocarbons (PAHs) are of particular concern. This study investigated the effect of ultraviolet (UV)-induced photocatalysis on the degradation of PAHs in PM2.5, employing titanium dioxide (TiO2)-supporting quartz fibre filters. A TiO2 layer was formed on the quartz fibre filters, and airborne PM2.5 was collected using an air sample at a flow rate of 500 L/min for 24 h. The PM2.5 samples were subsequently irradiated with ultraviolet rays at 1.1 mW/cm2. The amounts of nine targeted PAHs (phenanthrene, PHE; anthracene, ANT; pyrene, PYR; benzo[a]anthracene, BaA; chrysene, CHR; benzo[b]fluoranthene, BbF; benzo[k]fluoranthene, BkF; benzo[a]pyrene, BaP; and benzo[g,h,i]perylene, BgP) gradually decreased during the treatment, with half-lives ranging from 18 h (PHE) to 3 h (BaP), and a significantly greater reduction was found in comparison with the PAHs collected in the control (non-TiO2 coated) quartz fibre filters. However, the degradation rates were much faster when the PAHs were in direct contact with the TiO2 layer. As PM2.5 is a mixture of various kinds of solids, co-existing components can be a rate-determining factor in the UV-induced degradation of PAHs. This was demonstrated by a remarkable increase in degradation rates following the removal of co-existing salts from the PM2.5 using water treatment.
Rapid and Progressive Loss of Multiple Retinal Cell Types in Cathepsin D-Deficient Mice—An Animal Model of CLN10 Disease
Authors: Bassal Mahmoud , Liu Junling , Jankowiak Wanda , Saftig Paul , Bartsch Udo
Published: March 2021

Vision loss is among the characteristic symptoms of neuronal ceroid lipofuscinosis (NCL), a fatal neurodegenerative lysosomal storage disorder. Here, we performed an in-depth analysis of retinal degeneration at the molecular and cellular levels in mice lacking the lysosomal aspartyl protease cathepsin D, an animal model of congenital CLN10 disease. We observed an early-onset accumulation of storage material as indicated by elevated levels of saposin D and subunit C of the mitochondrial ATP synthase. The accumulation of storage material was accompanied by reactive astrogliosis and microgliosis, elevated expression of the autophagy marker sequestosome 1/p62 and a dysregulated expression of several lysosomal proteins. The number of cone photoreceptor cells was reduced as early as at postnatal day 5. At the end stage of the disease, the outer nuclear layer was almost atrophied, and all cones were lost. A significant loss of rod and cone bipolar cells, amacrine cells and ganglion cells was found at advanced stages of the disease. Results demonstrate that cathepsin D deficiency results in an early-onset and rapidly progressing retinal dystrophy that involves all retinal cell types. Data of the present study will serve as a reference for studies aimed at developing treatments for retinal degeneration in CLN10 disease.
Impact of Seasonal Variation in Climate on Water Quality of Old Woman Creek Watershed Ohio Using SWAT
Authors: Olaoye Israel A. , Confesor Remegio B. , Ortiz Joseph D.
Published: March 2021

The effect of the projected 21st century climate change on water quality in Old Woman Creek (OWC) watershed was evaluated using the Soil and Water Assessment Tool (SWAT) and the precipitation and temperature projections from three best Global Climate Circulation Model (GCM)l ensemble downloaded from the Coupled Model Intercomparison Project Phase 5 (CMIP5). These three best GCMs (GFDL-ESM2M, MPI-ESM-MR, EC-EARTH) were identified as those closest to the multivariate ensemble average of twenty different GCM-driven SWAT simulations. Seasonal analysis was undertaken in historical (1985–2014), current to near future (2018–2045), mid-century (2046–2075), and late-century (2076–2100) climate windows. The hydrological model calibration was carried out using a multi-objective evolutionary algorithm and pareto optimization. Simulations were made for stream flow and nine water quality variables (sediment, organic nitrogen, organic phosphorus, mineral phosphorus, chlorophyll a, carbonaceous biochemical oxygen demand, dissolved oxygen, total nitrogen, and total phosphorus) of interest. The average of twenty different CMIP5-driven SWAT simulation results showed good correlation for all the 10 variables with the PRISM-driven SWAT simulation results in the historical climate window (1985–2014). For the historical period, the result shows an over-estimation of flow, sediment, and organic nitrogen from January to March in simulations with CMIP5 inputs, relative to simulations with PRISM input. For the other climate windows, the simulation results show a progressive increase in stream flow with peak flow month shifting from April to March. The expected seasonal changes in each water quality variable have implications for the OWC estuary and Lake Erie water quality.
Biocomposite Materials Based on Chitosan and Lignin: Preparation and Characterization
Authors: Rosova Elena , Smirnova Natalia , Dresvyanina Elena , Smirnova Valentina , Vlasova Elena , Ivan’kova Elena , Sokolova Maria , Maslennikova Tatiana , Malafeev Konstantin , Kolbe Konstantin , Kanerva Mikko , Yudin Vladimir
Published: March 2021

In this study, bioactive composite systems based on natural polymers (chitosan and lignin) were prepared in this study. The structural, mechanical, and morphological properties of chitosan-based materials containing various amounts of lignin filler were investigated. The infra-red IR spectroscopy data confirmed the formation of chemical bonds between the components of the obtained composites. The mechanical properties of film samples were studied in air and in physiological solution. It was demonstrated that the breaking elongation values of the obtained film samples in the wet state were higher (150–160%) than the corresponding (average) value of a pure chitosan film (100%). The scanning electron microscopy and atomic force microscopy data demonstrated that the introduction of lignin had caused significant changes in the surface morphology of films. The appearance of a strongly pronounced texture and porosity facilitated cell proliferation on the surface of composites, i.e., the bioactivity of film samples was enhanced with an increasing lignin content in the chitosan matrix.
Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction
Authors: Kim Chan-Jung
Published: March 2021

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.
Eciton Army Ants—Umbrella Species for Conservation in Neotropical Forests
Authors: Pérez-Espona Sílvia
Published: March 2021

Identification of priority areas for conservation is crucial for the maintenance and protection of biodiversity, particularly in tropical forests where biodiversity continues to be lost at alarming rates. Surveys and research on umbrella species can provide efficient and effective approaches to identify potential areas for conservation at small geographical scales. Army ants of the genus Eciton are keystone species in neotropical forests due to their major role as top predators and due to the numerous vertebrate- and invertebrate associated species that depend upon their colonies for survival. These associates range from the iconic army ant-following birds to a wide range of arthropod groups, some of which have evolved intricate morphological, behavioural and/or chemical strategies to conceal their presence and integrate into the colony life. Furthermore, Eciton colonies require large forested areas that support a diverse leaf litter prey community and several field-based and genetic studies have demonstrated the negative consequences of forest fragmentation for the long-term maintenance of these colonies. Therefore, Eciton species will not only act as umbrella for their associates but also for many other species in neotropical forests, in particular for those that require a large extent of forest. This review summarises past and recent accounts of the main taxonomic groups found associated with Eciton colonies, as well research assessing the impact of forest fragmentation on this army ant, to encourage the adoption of Eciton army ants as umbrella species for the identification of priority areas for conservation and assessments of the effect of disturbance in neotropical forests.
A Generative Adversarial Network for Infrared and Visible Image Fusion Based on Semantic Segmentation
Authors: Hou Jilei , Zhang Dazhi , Wu Wei , Ma Jiayi , Zhou Huabing
Published: March 2021

This paper proposes a new generative adversarial network for infrared and visible image fusion based on semantic segmentation (SSGAN), which can consider not only the low-level features of infrared and visible images, but also the high-level semantic information. Source images can be divided into foregrounds and backgrounds by semantic masks. The generator with a dual-encoder-single-decoder framework is used to extract the feature of foregrounds and backgrounds by different encoder paths. Moreover, the discriminator’s input image is designed based on semantic segmentation, which is obtained by combining the foregrounds of the infrared images with the backgrounds of the visible images. Consequently, the prominence of thermal targets in the infrared images and texture details in the visible images can be preserved in the fused images simultaneously. Qualitative and quantitative experiments on publicly available datasets demonstrate that the proposed approach can significantly outperform the state-of-the-art methods.
Technology as Thirdspace: Teachers in Scottish Schools Engaging with and Being Challenged by Digital Technology in First COVID-19 Lockdown
Authors: Brown Jonathan , McLennan Carrie , Mercieca Daniela , Mercieca Duncan P. , Robertson Derek P. , Valentine Eddie
Published: March 2021

This paper looks at the impact of digital technology on teaching and learning in primary schools in Scotland during the first COVID-19 lockdown from March to June 2020. The pandemic has challenged our understanding of schooling as, for the first time in many years, schools as we know them were shut and the school building was removed as the site of teaching and learning. This paper uses the concept of Thirdspace as developed by Edward Soja (1996), where Thirdspace is understood as an in-between space between binaries that enables the possibility to think and act otherwise. Drawing from qualitative data from interviews with primary school teachers, this paper explores how the lockdown in general, and digital technology in particular, facilitated a Thirdspace in the first COVID-19 lockdown. Findings from the study indicate that engaging with digital technology offers the teacher more possibilities than they have come to expect in the physical space of traditional schooling.
Atomic Network-Based DOA Estimation Using Low-Bit ADC
Authors: Sheng Shuran , Chen Peng , Yao Yuxuan , Wu Lenan , Chen Zhimin
Published: March 2021

In the direction of arrival (DOA) estimation problem, when a low-bit analog to digital converter (ADC) is used, the estimation performance severely deteriorates. In this paper, the DOA estimation problem is considered in a low-cost direction finding system with low-bit ADC. To eliminate quantization noise, we propose a novel network ADCnet, which is a composition of fully connected layers and exponential linear unit (ELU) layers, and the input signals are the received signals using low-bit ADC. After the ADCnet, an AtomicNet is also proposed to estimate the DOA from the denoised signals, where atomic vectors are corresponding to the steer vectors. A loss function considering both the reconstruction performance and the sparsity is proposed in the AtomicNet. Different from the exiting atomic norm-based methods, the proposed method can avoid an optimization problem and estimate the DOA with lower computational complexity. Simulation results show that the proposed method outperforms the existing methods in the DOA estimation performance using low-bit ADC.
Evaluation of a LoRa Mesh Network for Smart Metering in Rural Locations
Authors: Marahatta Anup , Rajbhandari Yaju , Shrestha Ashish , Singh Ajay , Thapa Anup , Gonzalez-Longatt Francisco , Korba Petr , Shin Seokjoo
Published: March 2021

Accompanying the advancement on the Internet of Things (IoT), the concept of remote monitoring and control using IoT devices is becoming popular. Digital smart meters hold many advantages over traditional analog meters, and smart metering is one of application of IoT technology. It supports the conventional power system in adopting modern concepts like smart grids, block-chains, automation, etc. due to their remote load monitoring and control capabilities. However, in many applications, the traditional analog meters still are preferred over digital smart meters due to the high deployment and operating costs, and the unreliability of the smart meters. The primary reasons behind these issues are a lack of a reliable and affordable communication system, which can be addressed by the deployment of a dedicated network formed with a Low Power Wide Area (LPWA) platform like wireless radio standards (i.e., LoRa devices). This paper discusses LoRa technology and its implementation to solve the problems associated with smart metering, especially considering the rural energy system. A simulation-based study has been done to analyse the LoRa technology’s applicability in different architecture for smart metering purposes and to identify a cost-effective and reliable way to implement smart metering, especially in a rural microgrid (MG).
Complex-Valued Pix2pix—Deep Neural Network for Nonlinear Electromagnetic Inverse Scattering
Authors: Guo Liang , Song Guanfeng , Wu Hongsheng
Published: March 2021

Nonlinear electromagnetic inverse scattering is an imaging technique with quantitative reconstruction and high resolution. Compared with conventional tomography, it takes into account the more realistic interaction between the internal structure of the scene and the electromagnetic waves. However, there are still open issues and challenges due to its inherent strong non-linearity, ill-posedness and computational cost. To overcome these shortcomings, we apply an image translation network, named as Complex-Valued Pix2pix, on the inverse scattering problem of electromagnetic field. Complex-Valued Pix2pix includes two parts of Generator and Discriminator. The Generator employs a multi-layer complex valued convolutional neural network, while the Discriminator computes the maximum likelihoods between the original value and the reconstructed value from the aspects of the two parts of the complex: real part and imaginary part, respectively. The results show that the Complex-Valued Pix2pix can learn the mapping from the initial contrast to the real contrast in microwave imaging models. Moreover, due to the introduction of discriminator, Complex-Valued Pix2pix can capture more features of nonlinearity than traditional Convolutional Neural Network (CNN) by confrontation training. Therefore, without considering the time cost of training, Complex-Valued Pix2pix may be a more effective way to solve inverse scattering problems than other deep learning methods. The main improvement of this work lies in the realization of a Generative Adversarial Network (GAN) in the electromagnetic inverse scattering problem, adding a discriminator to the traditional Convolutional Neural Network (CNN) method to optimize network training. It has the prospect of outperforming conventional methods in terms of both the image quality and computational efficiency.
The Degradation Behavior of LiFePO4/C Batteries during Long-Term Calendar Aging
Authors: Sui Xin , Świerczyński Maciej , Teodorescu Remus , Stroe Daniel-Ioan
Published: March 2021

With widespread applications for lithium-ion batteries in energy storage systems, the performance degradation of the battery attracts more and more attention. Understanding the battery’s long-term aging characteristics is essential for the extension of the service lifetime of the battery and the safe operation of the system. In this paper, lithium iron phosphate (LiFePO4) batteries were subjected to long-term (i.e., 27–43 months) calendar aging under consideration of three stress factors (i.e., time, temperature and state-of-charge (SOC) level) impact. By means of capacity measurements and resistance calculation, the battery’s long-term degradation behaviors were tracked over time. Battery aging models were established by a simple but accurate two-step nonlinear regression approach. Based on the established model, the effect of the aging temperature and SOC level on the long-term capacity fade and internal resistance increase of the battery is analyzed. Furthermore, the storage life of the battery with respect to different stress factors is predicted. The analysis results can hopefully provide suggestions for optimizing the storage condition, thereby prolonging the lifetime of batteries.
Improvement in Torque Density by Ferrofluid Injection into Magnet Tolerance of Interior Permanent Magnet Synchronous Motor
Authors: Yang In-Jun , Song Si-Woo , Kim Dong-Ho , Kim Kwang-Soo , Kim Won-Ho
Published: March 2021

In an interior permanent magnet synchronous motor, an adhesive such as bond is generally injected into the magnet tolerance to prevent vibration of the permanent magnet within the insertion space. In this case, a disadvantage is that the magnet tolerance does not contribute to the performance. In this paper, ferrofluid is inserted to improve the torque density, utilizing the magnet tolerance. When inserting ferrofluid into the magnet tolerance, it is important to fix the magnet because conventional adhesives are not used, and it is important that the ferrofluid does not act as a leakage path within the insertion space. In this study, a new rotor configuration using a plastic barrier that satisfies these considerations was introduced. The analysis was conducted through finite element analysis (FEA), and this technique was verified by comparing the simulation results and the experimental results through a dynamo test. It was confirmed that the no-load back electromotive force in the final model increased through ferrofluid injection.
Crystal Engineering Approach for Fabrication of Inverted Perovskite Solar Cell in Ambient Conditions
Authors: Ermanova Inga , Yaghoobi Nia Narges , Lamanna Enrico , Di Bartolomeo Elisabetta , Kolesnikov Evgeny , Luchnikov Lev , Di Carlo Aldo
Published: March 2021

In this paper, we demonstrate the high potentialities of pristine single-cation and mixed cation/anion perovskite solar cells (PSC) fabricated by sequential method deposition in p-i-n planar architecture (ITO/NiOX/Perovskite/PCBM/BCP/Ag) in ambient conditions. We applied the crystal engineering approach for perovskite deposition to control the quality and crystallinity of the light-harvesting film. The formation of a full converted and uniform perovskite absorber layer from poriferous pre-film on a planar hole transporting layer (HTL) is one of the crucial factors for the fabrication of high-performance PSCs. We show that the in-air sequential deposited MAPbI3-based PSCs on planar nickel oxide (NiOX) permitted to obtain a Power Conversion Efficiency (PCE) exceeding 14% while the (FA,MA,Cs)Pb(I,Br)3-based PSC achieved 15.6%. In this paper we also compared the influence of transporting layers on the cell performance by testing material depositions quantity and thickness (for hole transporting layer), and conditions of deposition processes (for electron transporting layer). Moreover, we optimized second step of perovskite deposition by varying the dipping time of substrates into the MA(I,Br) solution. We have shown that the layer by layer deposition of the NiOx is the key point to improve the efficiency for inverted perovskite solar cell out of glove-box using sequential deposition method, increasing the relative efficiency of +26% with respect to reference cells.
Global Oil Price and Innovation for Sustainability: The Impact of R&D Spending, Oil Price and Oil Price Volatility on GHG Emissions
Authors: Mohamued Elyas Abdulahi , Ahmed Masood , Pypłacz Paula , Liczmańska-Kopcewicz Katarzyna , Khan Muhammad Asif
Published: March 2021

Recently, sustainable economic growth has taken the front line of the global development agenda. The common dependency on fossil fuel energy, greenhouse gas (GHG) emissions and the continuous rising demands for energy have posed challenges that put the world in a climate change trap. This work empirically analyzes the effect of innovation, oil price, oil price volatility and economic growth on GHG emissions over the period of 1991–2015. The study compares the emission level between European Union countries (EU) (26), oil-producing countries (22), China and the United States of America (USA) using the Driscoll–Kraay model. The main empirical finding points to a positive effect of innovation on GHG emission reduction initiatives in oil-importing economies. Particularly, EU countries significantly minimized emissions due to innovation, followed by China and the USA. Contrarily, the effect of innovation increases GHG emission in oil-exporting economies. The results also indicate broader significant effects of oil price and oil price volatility on GHG emission. Interestingly, the effect of oil price on GHG emission is asymmetrical between oil-exporting and -importing economies. Oil price increases in oil-importing countries decrease GHG emission; contrarily, its effect increases emissions in oil-exporting countries. Thus, oil-exporting countries lack motivation to decrease emission levels due to oil price escalation. Unlike the oil price, oil price volatility comparably decreases GHG emissions in oil-exporting and -importing economies. Thus, one might be tempted to take oil price volatility and the future uncertainty of oil price as a virtuous instance rather than oil price increment. Thus, policymakers need to pay attention to market forces and policy measures to monitor GHG emissions due to economic activities. The results are also robust under the alternative econometrics estimation model of generalized method of moments (GMM)-Differenced.
Optimization of 5G Networks for Smart Logistics
Authors: Khatib Emil Jatib , Barco Raquel
Published: March 2021

Industry 4.0 is generalizing the use of wireless connectivity in manufacturing and logistics. Specifically, in Smart Logistics, novel Industry 4.0 technologies are used to enable agile supply chains, with reduced management, energy and storage costs. Cellular networks allow connectivity throughout all the scenarios where logistics processes take place, each having their own challenges. This paper explores such scenarios and challenges, and proposes 5G technology as a global unified connectivity solution. Moreover, this paper proposes a system for exploiting the application-specific optimization capabilities of 5G networks to better cater for the needs of Smart Logistics. An application traffic modeling process is proposed, along with a proactive approach to network optimization that can improve the Quality of Service and reduce connectivity costs.
Assessing the Level of Energy and Climate Sustainability in the European Union Countries in the Context of the European Green Deal Strategy and Agenda 2030
Authors: Tutak Magdalena , Brodny Jarosław , Bindzár Peter
Published: March 2021

The concept of sustainable development integrates activities in the economic, environmental and social areas. Energy policy, which is very closely linked to climate protection, is of key importance for achieving the goals of the concept in question. All these elements are connected by the European Green Deal strategy and Agenda 2030. Their implementation requires the evaluation of previous actions undertaken within the framework of sustainable development and the diagnosis of the current state. Therefore, this article presents the results of such research in relation to the key industry connected with this process, which is the energy sector. The research methodology was based on the analysis of 14 indicators that characterize four basic areas (dimensions) related to energy and climate sustainability. These indicators concern energy and climate as well as social and economic issues. This approach makes it possible to comprehensively assess the actions taken so far in the implementation of sustainable economic development in the energy and climate area in the European Union (EU) countries. The entropy-complex-proportional-assessment (COPRAS) methodologies, which belong to the group of multiple criteria decision-making methods, were used for this study. The conducted research allowed for the assessment of the changes in the EU countries in terms of energy and climate sustainability between 2009–2018. In addition, the effects of the introduced changes in individual years and in relation to the studied areas (dimensions) were also evaluated. Based on the results, considering the adopted criteria, the EU countries were divided into groups similar to the level of energy and climate sustainability. The results constitute a valuable set of data, which allows for a wide and in-depth multicriteria analysis. This allows for a very objective and broad assessment of the effects of sustainable development policies in the EU countries and the current state in the context of the European Green Deal strategy and Agenda 2030.
Analysis of Harmful Exhaust Gas Concentrations in Cloud behind a Vehicle with a Spark Ignition Engine
Authors: Rymaniak Łukasz , Kamińska Michalina , Szymlet Natalia , Grzeszczyk Rafał
Published: March 2021

The article presents issues related to the assessment of concentrations of harmful substances in the exhaust gas cloud behind the vehicle. In the theoretical part, considerations about the harmfulness of exhaust gases and methods of detection of chemical compounds were made, and the issues of von Karman vortices and the Lambert-Beer law were referred to. The test object was a vehicle equipped with an SI engine meeting the Euro 3 standard. The drive unit had a capacity of 2.8 dm3, a rated power reaching 142 kW at 5500 rpm and a maximum torque of 280 Nm at 3500 rpm. The measurements of the dilution of the exhaust gas cloud behind the vehicle were made in stationary conditions (laboratory) and during actual operation in the Poznań agglomeration. In the research, technically advanced equipment from the PEMS group was used. In the analysis of the obtained results, detailed considerations were made regarding the influence of the location of the measuring probe in relation to the exhaust system. As can be seen from the obtained dependencies, the vehicle motion is favorable for the assessment of concentrations behind a moving object, because the ecological indicators at successive distances behind the exhaust system achieve better parameters in most points than in a stationary test.
Lactate Metabolism and Microbiome Composition Are Affected by Nitrogen Gas Supply in Continuous Lactate-Based Chain Elongation
Authors: Contreras-Dávila Carlos A. , Ali Arielle , Buisman Cees J. N. , Strik David P. B. T. B.
Published: March 2021

Chain elongation reactor microbiomes produce valuable medium-chain carboxylates (MCC) from non-sterile residual substrates where lactate is a relevant intermediate. Gas supply has been shown to impact chain elongation performance. In the present study, the effect of nitrogen gas (N2) supply on lactate metabolism, conversion rates, biomass growth, and microbiome composition was evaluated in a lactate-fed upflow anaerobic reactor with continuous or intermittent N2 gas supply. Successful MCC production was achieved with continuous N2 gas supply at low superficial gas velocities (SGV) of 0.22 m∙h−1. Supplying N2 at high SGV (>2 m∙h−1) either continuously (2.2 m∙h−1) or intermittently (3.6 m∙h−1) disrupted chain elongation, resulting in production of short-chain carboxylates (SCC), i.e., acetate, propionate, and n-butyrate. Caproiciproducens-dominated chain-elongating microbiomes enriched at low SGV were washed out at high SGV where Clostridium tyrobutyricum-dominated microbiomes thrived, by displaying higher lactate consumption rates. Suspended growth seemed to be dominant regardless of SGV and gas supply regime applied with no measurable sludge bed formed. The highest MCC production from lactate of 10 g COD∙L−1∙d−1 with electron selectivities of 72 ± 5%was obtained without N2 gas supply at a hydraulic retention time (HRT) of 1 day. The addition of 5 g∙L−1 of propionate did not inhibit chain elongation, but rather boosted lactate conversion rates towards MCC with n-heptylate reaching 1.8 g COD∙L−1∙d−1. N2 gas supply can be used for mixing purposes and to steer lactate metabolism to MCC or SCC production.
A Characterization of the Dynamics of Schröder’s Method for Polynomials with Two Roots
Authors: Galilea Víctor , Gutiérrez José M.
Published: March 2021

The purpose of this work is to give a first approach to the dynamical behavior of Schröder’s method, a well-known iterative process for solving nonlinear equations. In this context, we consider equations defined in the complex plane. By using topological conjugations, we characterize the basins of attraction of Schröder’s method applied to polynomials with two roots and different multiplicities. Actually, we show that these basins are half-planes or circles, depending on the multiplicities of the roots. We conclude our study with a graphical gallery that allow us to compare the basins of attraction of Newton’s and Schröder’s method applied to some given polynomials.