bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Pyridyl–Oxazole Carboxamides: Toxicity Assay Determination in Fungi and Zebrafish Embryos
Authors: Chen Shu , Zhang Dong-Lin , Ren Chao-Li , Zou Wen-Qian , Tian Xiao-Yu , Du Xiao-Hua , Tan Cheng-Xia
Published: June 2021

Eight novel pyridyl–oxazole carboxamides were evaluated against fungi and displayed good fungicidal activities against Botrytis cinereal and Rhizoctonia solani. Preliminary bioassay results indicated that at 100 mg/L, compounds 6a–6e, 6g and 6h exhibited 100% fungicidal activities against Botrytis cinerea, and the compound 6b to Rhizoctonia solani at 100%. Then, the zebrafish embryo acute toxicity test was performed to assess the toxicity of 6b and 6c. A series of malformations appeared, when the zebrafish embryos were exposed to 6b and 6c, such as delayed yolk sac resorption, significant shortening of body length, pericardial edema, bending spine, lack of melanin, heart hemorrhage, head hemorrhage, delayed swim sac development, yolk malformation and head malformation. In addition, the acute toxicity of 6b to zebrafish embryo is 4.878 mg/L, and 6c is 6.257 mg/L.
Theoretical Studies on the Binding Mode and Reaction Mechanism of TLP Hydrolase kpHIUH
Authors: Wang Xixi , Shan Jiankai , Liu Wei , Li Jing , Tan Hongwei , Li Xichen , Chen Guangju
Published: June 2021

In this work, we have investigated the binding conformations of the substrate in the active site of 5-HIU hydrolase kpHIUH and its catalytic hydrolysis mechanism. Docking calculations revealed that the substrate adopts a conformation in the active site with its molecular plane laying parallel to the binding interface of the protein dimer of kpHIUH, in which His7 and His92 are located adjacent to the hydrolysis site C6 and have hydrogen bond interactions with the lytic water. Based on this binding conformation, density functional theory calculations indicated that the optimal catalytic mechanism consists of two stages: (1) the lytic water molecule is deprotonated by His92 and carries out nucleophilic attack on C6=O of 5-HIU, resulting in an oxyanion intermediate; (2) by accepting a proton transferred from His92, C6–N5 bond is cleaved to completes the catalytic cycle. The roles of His7, His92, Ser108 and Arg49 in the catalytic reaction were revealed and discussed in detail.
Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing
Authors: Pudkon Watcharapong , Laomeephol Chavee , Damrongsakkul Siriporn , Kanokpanont Sorada , Ratanavaraporn Juthamas
Published: June 2021

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1–3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.
Analysis of Pathogenic Bacterial and Yeast Biofilms Using the Combination of Synchrotron ATR-FTIR Microspectroscopy and Chemometric Approaches
Authors: Cheeseman Samuel , Shaw Z. L. , Vongsvivut Jitraporn , Crawford Russell J. , Dupont Madeleine F. , Boyce Kylie J. , Gangadoo Sheeana , Bryant Saffron J. , Bryant Gary , Cozzolino Daniel , Chapman James , Elbourne Aaron , Truong Vi Khanh
Published: June 2021

Biofilms are assemblages of microbial cells, extracellular polymeric substances (EPS), and other components extracted from the environment in which they develop. Within biofilms, the spatial distribution of these components can vary. Here we present a fundamental characterization study to show differences between biofilms formed by Gram-positive methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative Pseudomonas aeruginosa, and the yeast-type Candida albicans using synchrotron macro attenuated total reflectance-Fourier transform infrared (ATR-FTIR) microspectroscopy. We were able to characterise the pathogenic biofilms’ heterogeneous distribution, which is challenging to do using traditional techniques. Multivariate analyses revealed that the polysaccharides area (1200–950 cm−1) accounted for the most significant variance between biofilm samples, and other spectral regions corresponding to amides, lipids, and polysaccharides all contributed to sample variation. In general, this study will advance our understanding of microbial biofilms and serve as a model for future research on how to use synchrotron source ATR-FTIR microspectroscopy to analyse their variations and spatial arrangements.
Chitosan, Polyethylene Glycol and Polyvinyl Alcohol Modified MgFe2O4 Ferrite Magnetic Nanoparticles in Doxorubicin Delivery: A Comparative Study In Vitro
Authors: Ramnandan Deevak , Mokhosi Seipati , Daniels Aliscia , Singh Moganavelli
Published: June 2021

Cancer-based magnetic theranostics has gained significant interest in recent years and can contribute as an influential archetype in the effective treatment of cancer. Owing to their excellent biocompatibility, minute sizes and reactive functional surface groups, magnetic nanoparticles (MNPs) are being explored as potential drug delivery systems. In this study, MgFe2O4 ferrite MNPs were evaluated for their potential to augment the delivery of the anticancer drug doxorubicin (DOX). These MNPs were successfully synthesized by the glycol-thermal method and functionalized with the polymers; chitosan (CHI), polyvinyl alcohol (PVA) and polyethylene glycol (PEG), respectively, as confirmed by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) confirmed the formation of the single-phase cubic spinel structures while vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic properties of all MNPs. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) revealed small, compact structures with good colloidal stability. CHI-MNPs had the highest DOX encapsulation (84.28%), with the PVA-MNPs recording the lowest encapsulation efficiency (59.49%). The 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) cytotoxicity assays conducted in the human embryonic kidney (HEK293), colorectal adenocarcinoma (Caco-2), and breast adenocarcinoma (SKBR-3) cell lines showed that all the drug-free polymerized MNPs promoted cell survival, while the DOX loaded MNPs significantly reduced cell viability in a dose-dependent manner. The DOX-CHI-MNPs possessed superior anticancer activity (<40% cell viability), with approximately 85.86% of the drug released after 72 h in a pH-responsive manner. These MNPs have shown good potential in enhancing drug delivery, thus warranting further optimizations and investigations.
White Tea Intake Abrogates Markers of Streptozotocin-Induced Prediabetes Oxidative Stress in Rat Lungs’
Authors: Silveira Ana C. , Rato Luís , Oliveira Pedro Fontes , Alves Marco G. , Silva Branca M.
Published: June 2021

Prediabetes (PrDM) is a prodromal stage of diabetes mellitus (DM) with an increasing prevalence worldwide. During DM progression, individuals gradually develop complications in various organs. However, lungs are suggested to be affected later than other organs, such as the eyes, heart or brain. In this work, we studied the effects of PrDM on male Wistar rats’ lungs and whether the regular consumption of white tea (WTEA) for 2 months contributes to the improvement of the antioxidant profile of this tissue, namely through improved activity of the first line defense antioxidant enzymes, the total antioxidant capacity and the damages caused in proteins, lipids and histone H2A. Our data shows that PrDM induced a decrease in lung superoxide dismutase and glutathione peroxidase activities and histone H2A levels and an increase in protein nitration and lipid peroxidation. Remarkably, the regular WTEA intake improved lung antioxidant enzymes activity and total antioxidant capacity and re-established the values of protein nitration, lipid peroxidation and histone H2A. Overall, this is the first time that lung is reported as a major target for PrDM. Moreover, it is also the first report showing that WTEA possesses relevant chemical properties against PrDM-induced lung dysfunction.
How Does Diet Influence Our Lives? Evaluating the Relationship between Isotopic Signatures and Mortality Patterns in Italian Roman Imperial and Medieval Periods
Authors: Baldoni Marica , Nardi Alessandra , De Angelis Flavio , Rickards Olga , Martínez-Labarga Cristina
Published: June 2021

The present research investigates the relationship between dietary habits and mortality patterns in the Roman Imperial and Medieval periods. The reconstructions of population dynamics and subsistence strategies provide a fascinating source of information for understanding our history. This is particularly true given that the changes in social, economic, political, and religious aspects related to the transition from the Roman period to the Middle Ages have been widely discussed. We analyzed the isotopic and mortality patterns of 616 individuals from 18 archeological sites (the Medieval Latium sites of Colonna, Santa Severa, Allumiere, Cencelle, and 14 Medieval and Imperial funerary contexts from Rome) to compile a survivorship analysis. A semi-parametric approach was applied, suggesting variations in mortality patterns between sexes in the Roman period. Nitrogen isotopic signatures influenced mortality in both periods, showing a quadratic and a linear effect for Roman Imperial and Medieval populations, respectively. No influence of carbon isotopic signatures has been detected for Roman Imperial populations. Conversely, increased mortality risk for rising carbon isotopic values was observed in Medieval samples.
Transmission of Soil Transmitted Helminthiasis in the Mifi Health District (West Region, Cameroon): Low Endemicity but Still Prevailing Risk
Authors: Sumo Laurentine , Otiobo Atibita Esther Nadine , Mache Eveline , Gangue Tiburce , Nana-Djeunga Hugues C.
Published: June 2021

The control of soil-transmitted helminthiasis (STH) in Cameroon is focused on large-scale deworming through annual mass drug administration (MDA) of albendazole or mebendazole to at-risk groups, principally pre-school and school-age children. After a decade of intervention, prevalence and intensity of infection have been significantly lowered, encouraging the paradigm shift from control to elimination. However, STH eggs are extremely resistant to environmental stressors and may survive for years in soils. It therefore appeared important to assess whether the risk of transmission was still prevailing, especially in a context where transmission of soil-transmitted helminths in the human population had almost been interrupted. A retrospective and a prospective cross-sectional surveys were conducted in five Health Areas of the Mifi Health District (West Region, Cameroon) to: (i) assess the trends in infestation rates over three-years (2018–2020) using health facility registers, and (ii) investigate, in 2020, the contamination rates of the environment by dissemination stages of soil-transmitted helminths using the sucrose centrifugal flotation method. The overall soil-transmitted helminth infestation rate was 4.9% (95% CI: 4.3–5.6), significantly lower than the overall soil contamination rate (12.0%; 95% CI: 8.2–17.2). These results are supportive of the low endemicity level of STHs in the Mifi Health District, but environmental pollution by dissemination stages of the parasites outlines that the risk of transmission is still persistent. It therefore appears compulsory to account for the environment when considering policy/recommendations for transmission interruption and stopping MDA, as it is in the case with vector-borne diseases.
In Vitro Production of Somaclones with Decreased Erucic Acid Content in Indian Mustard [Brassica juncea (Linn.) Czern&Coss]
Authors: Shyam Chitralekha , Tripathi Manoj Kumar , Tiwari Sushma , Tripathi Niraj , Solanki Ravindra Singh , Sapre Swapnil , Ahuja Ashok , Tiwari Sharad
Published: June 2021

Brassica juncea is a crucial cultivated mustard species and principal oilseed crop of India and Madhya Pradesh, grown for diverse vegetables, condiments, and oilseeds. Somaclonal variation was explored as a probable source of additional variability for the manipulation of fatty acids, especially low erucic acid contents that may be valuable for this commercially important plant species. The plantlets regenerated from tissue cultures (R0), their R1 generation and respective parental lines were compared for morpho-physiological traits and fatty acid profile for the probable existence of somaclonal variations. The first putative somaclone derived from genotype CS54 contained 5.48% and 5.52% erucic acid in R0 and R1 regenerants, respectively, compared to the mother plant (41.36%). In comparison, the second somaclone acquired from PM30 exhibited a complete absence of erucic acid corresponding to its mother plant (1.07%). These putative somaclones present a source of variation for exploitation in the development of future mustard crops with low erucic acid content.
Boosting Electrochemical Performance of Hematite Nanorods via Quenching-Induced Alkaline Earth Metal Ion Doping
Authors: Chen Qin , Chong Yanan , Rao Mumin , Su Ming , Qiu Yongcai
Published: June 2021

Ion doping in transition metal oxides is always considered to be one of the most effective methods to obtain high-performance electrochemical supercapacitors because of the introduction of defective surfaces as well as the enhancement of electrical conductivity. Inspired by the smelting process, an ancient method, quenching is introduced for doping metal ions into transition metal oxides with intriguing physicochemical properties. Herein, as a proof of concept, α-Fe2O3 nanorods grown on carbon cloths (α-Fe2O3@CC) heated at 400 °C are rapidly put into different aqueous solutions of alkaline earth metal salts at 4 °C to obtain electrodes doped with different alkaline earth metal ions (M-Fe2O3@CC). Among them, Sr-Fe2O3@CC shows the best electrochemical capacitance, reaching 77.81 mF cm−2 at the current of 0.5 mA cm−2, which is 2.5 times that of α-Fe2O3@CC. The results demonstrate that quenching is a feasible new idea for improving the electrochemical performances of nanostructured materials.
Network Pharmacology Study to Interpret Signaling Pathways of Ilex cornuta Leaves against Obesity
Authors: Oh Ki-Kwang , Adnan Md. , Cho Dong-Ha
Published: June 2021

Ilex cornuta Leaves (ICLs) are a representative and traditional prescription for controlling obesity. Nevertheless, the corresponding therapeutic compounds and related pharmacological mechanisms of such medication remain undocumented. The compounds from ICLs were identified by gas chromatography-mass spectrum (GC-MS), and SwissADME confirmed their physicochemical properties. Next, the target proteins related to compounds or obesity-associated proteins were retrieved from public databases. RPackage constructed the protein–protein interaction (PPI) network, a bubble chart, and signaling pathways–target proteins–compounds (STC) network. Lastly, a molecular docking test (MDT) was performed to evaluate the affinity between target proteins and ligands from ICLs. GC-MS detected a total of 51 compounds from ICLs. The public databases identified 219 target proteins associated with selective compounds, 3028 obesity-related target proteins, and 118 overlapping target proteins. Moreover, the STC network revealed 42 target proteins, 22 signaling pathways, and 39 compounds, which were viewed to be remedially significant. The NOD-like receptor (NLR) signaling pathway was considered a key signaling pathway from the bubble chart. In parallel, the MDT identified three target proteins (IL6, MAPK1, and CASP1) on the NLR signaling pathway and four compounds against obesity. Overall, four compounds from ICLs might show anti-obesity synergistic efficacy by inactivating the NLR signaling pathway.
Computer Vision, IoT and Data Fusion for Crop Disease Detection Using Machine Learning: A Survey and Ongoing Research
Authors: Ouhami Maryam , Hafiane Adel , Es-Saady Youssef , El Hajji Mohamed , Canals Raphael
Published: June 2021

Crop diseases constitute a serious issue in agriculture, affecting both quality and quantity of agriculture production. Disease control has been a research object in many scientific and technologic domains. Technological advances in sensors, data storage, computing resources and artificial intelligence have shown enormous potential to control diseases effectively. A growing body of literature recognizes the importance of using data from different types of sensors and machine learning approaches to build models for detection, prediction, analysis, assessment, etc. However, the increasing number and diversity of research studies requires a literature review for further developments and contributions in this area. This paper reviews state-of-the-art machine learning methods that use different data sources, applied to plant disease detection. It lists traditional and deep learning methods associated with the main data acquisition modalities, namely IoT, ground imaging, unmanned aerial vehicle imaging and satellite imaging. In addition, this study examines the role of data fusion for ongoing research in the context of disease detection. It highlights the advantage of intelligent data fusion techniques, from heterogeneous data sources, to improve plant health status prediction and presents the main challenges facing this field. The study concludes with a discussion of several current issues and research trends.
Creating a Field-Wide Forage Canopy Model Using UAVs and Photogrammetry Processing
Authors: Minch Cameron , Dvorak Joseph , Jackson Josh , Sheffield Stuart Tucker
Published: June 2021

Alfalfa canopy structure reveals useful information for managing this forage crop, but manual measurements are impractical at field-scale. Photogrammetry processing with images from Unmanned Aerial Vehicles (UAVs) can create a field-wide three-dimensional model of the crop canopy. The goal of this study was to determine the appropriate flight parameters for the UAV that would enable reliable generation of canopy models at all stages of alfalfa growth. Flights were conducted over two separate fields on four different dates using three different flight parameters. This provided a total of 24 flights. The flight parameters considered were the following: 30 m altitude with 90° camera gimbal angle, 50 m altitude with 90° camera gimbal angle, and 50 m altitude with 75° camera gimbal angle. A total of 32 three-dimensional canopy models were created using photogrammetry. Images from each of the 24 flights were used to create 24 separate models and images from multiple flights were combined to create an additional eight models. The models were analyzed based on Model Ground Sampling Distance (GSD), Model Root Mean Square Error (RMSE), and camera calibration difference. Of the 32 attempted models, 30 or 94% were judged acceptable. The models were then used to estimate alfalfa yield and the best yield estimates occurred with flights at a 50 m altitude with a 75° camera gimbal angle; therefore, these flight parameters are suggested for the most consistent results.
Tell Me, What Do You See?—Interpretable Classification of Wiring Harness Branches with Deep Neural Networks
Authors: Kicki Piotr , Bednarek Michał , Lembicz Paweł , Mierzwiak Grzegorz , Szymko Amadeusz , Kraft Marek , Walas Krzysztof
Published: June 2021

In the context of the robotisation of industrial operations related to manipulating deformable linear objects, there is a need for sophisticated machine vision systems, which could classify the wiring harness branches and provide information on where to put them in the assembly process. However, industrial applications require the interpretability of the machine learning system predictions, as the user wants to know the underlying reason for the decision made by the system. We propose several different neural network architectures that are tested on our novel dataset to address this issue. We conducted various experiments to assess the influence of modality, data fusion type, and the impact of data augmentation and pretraining. The outcome of the network is evaluated in terms of the performance and is also equipped with saliency maps, which allow the user to gain in-depth insight into the classifier’s operation, including a way of explaining the responses of the deep neural network and making system predictions interpretable by humans.
Densely Deployed Indoor Massive MIMO Experiment: From Small Cells to Spectrum Sharing to Cooperation
Authors: Guevara Andrea P. , Pollin Sofie
Published: June 2021

Massive MIMO is a key 5G technology that achieves high spectral efficiency and capacity by significantly increasing the number of antennas per cell. Furthermore, due to precoding, massive MIMO allows co-channel interference cancellation across cells. In this work, based on experimental channel data for an indoor scenario, we analyse the impact of inter and intra-cell interference suppression in terms of spectral efficiency, capacity, user fairness and computational cost for three simulated systems under different cooperation levels. The first scenario assumes a cooperative case where eight neighbouring cells share the spectrum and infrastructure. This scenario provides the highest system performance; however, user fairness is achieved only when there is inter and intra-cell interference suppression. The second scenario considers eight cells that only share the spectrum; with full intra-cell and inter-cell interference cancellation, it is possible to achieve 32% of the optimal capacity with 20% of the computational cost in each distributed CPU, although the total computational cost per system is the highest. The third scenario considers eight independent cells operating in different frequency bands; in this case, intra-cell interference suppression leads to higher spectral efficiency compared to the cooperative case without intra-cell interference suppression.
Clustering-Based Noise Elimination Scheme for Data Pre-Processing for Deep Learning Classifier in Fingerprint Indoor Positioning System
Authors: Liu Shuzhi , Sinha Rashmi Sharan , Hwang Seung-Hoon
Published: June 2021

Wi-Fi-based indoor positioning systems have a simple layout and a low cost, and they have gradually become popular in both academia and industry. However, due to the poor stability of Wi-Fi signals, it is difficult to accurately decide the position based on a received signal strength indicator (RSSI) by using a traditional dataset and a deep learning classifier. To overcome this difficulty, we present a clustering-based noise elimination scheme (CNES) for RSSI-based datasets. The scheme facilitates the region-based clustering of RSSIs through density-based spatial clustering of applications with noise. In this scheme, the RSSI-based dataset is preprocessed and noise samples are removed by CNES. This experiment was carried out in a dynamic environment, and we evaluated the lab simulation results of CNES using deep learning classifiers. The results showed that applying CNES to the test database to eliminate noise will increase the success probability of fingerprint location. The lab simulation results show that after using CNES, the average positioning accuracy of margin-zero (zero-meter error), margin-one (two-meter error), and margin-two (four-meter error) in the database increased by 17.78%, 7.24%, and 4.75%, respectively. We evaluated the simulation results with a real time testing experiment, where the result showed that CNES improved the average positioning accuracy to 22.43%, 9.15%, and 5.21% for margin-zero, margin-one, and margin-two error, respectively.
Efficient Data Communication Using Distributed Ledger Technology and IOTA-Enabled Internet of Things for a Future Machine-to-Machine Economy
Authors: Akhtar Mohd Majid , Rizvi Danish Raza , Ahad Mohd Abdul , Kanhere Salil S. , Amjad Mohammad , Coviello Giuseppe
Published: June 2021

A potential rise in interest in the Internet of Things in the upcoming years is expected in the fields of healthcare, supply chain, logistics, industries, smart cities, smart homes, cyber physical systems, etc. This paper discloses the fusion of the Internet of Things (IoT) with the so-called “distributed ledger technology” (DLT). IoT sensors like temperature sensors, motion sensors, GPS or connected devices convey the activity of the environment. Sensor information acquired by such IoT devices are then stored in a blockchain. Data on a blockchain remains immutable however its scalability still remains a challenging issue and thus represents a hindrance for its mass adoption in the IoT. Here a communication system based on IOTA and DLT is discussed with a systematic architecture for IoT devices and a future machine-to-machine (M2M) economy. The data communication between IoT devices is analyzed using multiple use cases such as sending DHT-11 sensor data to the IOTA tangle. The value communication is analyzed using a novel “micro-payment enabled over the top” (MP-OTT) streaming platform that is based on the “pay-as-you-go” and “consumption based” models to showcase IOTA value transactions. In this paper, we propose an enhancement to the classical “masked authenticated message” (MAM) communication protocol and two architectures called dual signature masked authenticated message (DSMAM) and index-based address value transaction (IBAVT). Further, we provided an empirical analysis and discussion of the proposed techniques. The implemented solution provides better address management with secured sharing and communication of IoT data, complete access control over the ownership of data and high scalability in terms of number of transactions that can be handled.
Emitter Identification of Digital Modulation Transmitter Based on Nonlinearity and Modulation Distortion of Power Amplifier
Authors: Chen Yue , Chen Xiang , Lei Yingke
Published: June 2021

Specific transmitter identification (SEI) is a technology that uses a received signal to identify to which individual radiation source the transmitted signal belongs. It can complete the identification of the signal transmitter in a non-cooperative scenario. Therefore, there are broad application prospects in the field of wireless-communication-network security, spectral resource management, and military battlefield-target communication countermeasures. This article demodulates and reconstructs a digital modulation signal to obtain a signal without modulator distortion and power-amplifier nonlinearity. Comparing the reconstructed signal with the actual received signal, the coefficient representation of the nonlinearity of the power amplifier and the distortion of the modulator can be obtained, and these coefficients can be used as the fingerprint characteristics of different transmitters through a convolutional neural network (CNN) to complete the identification of specific transmitters. The existing SEI strategy for changing the modulation parameters of a test signal is to mix part of the test signal with the training signal so that the classifier can learn the signal of which the modulation parameter was changed. This method is still data-oriented and cannot process signals for which the classifier has not been trained. It has certain limitations in practical applications. We compared the fingerprint features extracted by the method in this study with the fingerprint features extracted by the bispectral method. When SNR < 20 dB, the recognition accuracy of the bispectral method dropped rapidly. The method in this paper still achieved 86% recognition accuracy when SNR = 0 dB. When the carrier frequency of the test signal was changed, the bispectral feature failed, and the proposed method could still achieve a recognition accuracy of about 70%. When changing the test-signal baud rate, the proposed method could still achieve a classification accuracy rate of more than 70% for four different individual radiation sources when SNR = 0 dB.
Discrete Fourier Transform Radar in the Terahertz-Wave Range Based on a Resonant-Tunneling-Diode Oscillator
Authors: Konno Hiroki , Dobroiu Adrian , Suzuki Safumi , Asada Masahiro , Ito Hiroshi
Published: June 2021

We used a resonant-tunneling-diode (RTD) oscillator as the source of a terahertz-wave radar based on the principle of the swept-source optical coherence tomography (SS-OCT). Unlike similar reports in the terahertz range, we apply the stepwise frequency modulation to a subcarrier obtained by amplitude modulation instead of tuning the terahertz carrier frequency. Additionally, we replace the usual optical interference with electrical mixing and, by using a quadrature mixer, we can discriminate between negative and positive optical path differences, which doubles the measurement range without increasing the measurement time. To measure the distance to multiple targets simultaneously, the terahertz wave is modulated in amplitude at a series of frequencies; the signal returning from the target is detected and homodyne mixed with the original modulation signal. A series of voltages is obtained; by Fourier transformation the distance to each target is retrieved. Experimental results on one and two targets are shown.
Analytical Methods for Extraction and Identification of Primary and Secondary Metabolites of Apple (Malus domestica) Fruits: A Review
Authors: Acquavia Maria , Pascale Raffaella , Foti Luca , Carlucci Giuseppe , Scrano Laura , Martelli Giuseppe , Brienza Monica , Coviello Donatella , Bianco Giuliana , Lelario Filomena
Published: June 2021

Apples represent a greater proportion of the worldwide fruit supply, due to their availability on the market and to the high number of existing cultivar varieties and apple-based products (fresh fruit, fruit juice, cider and crushed apples). Several studies on apple fruit metabolites are available, with most of them focusing on their healthy properties’ evaluation. In general, the metabolic profile of apple fruits strongly correlates with most of their peculiar characteristics, such as taste, flavor and color. At the same time, many bioactive molecules could be identified as markers of a specific apple variety. Therefore, a complete description of the analytical protocols commonly used for apple metabolites’ characterization and quantification could be useful for researchers involved in the identification of new phytochemical compounds from different apple varieties. This review describes the analytical methods published in the last ten years, in order to analyze the most important primary and secondary metabolites of Malus domestica fruits. In detail, this review gives an account of the spectrophotometric, chromatographic and mass spectrometric methods. A discussion on the quantitative and qualitative analytical shortcomings for the identification of sugars, fatty acids, polyphenols, organic acids, carotenoids and terpenes found in apple fruits is reported.
Public Participation and Governance Performance in Gender-Imbalanced Central Rural China: The Roles of Trust and Risk Perception
Authors: Song Ruixia , Li Shuzhuo , Feldman Marcus W.
Published: June 2021

The study investigates the impact of public participation on governance performance in a risk society. A trust-based participatory paradigm is proposed as a viable framework. Using data from a 2018 survey of family planning services in Hubei, China, this study develops hypotheses drawn from causal mechanisms of participatory governance. A structural equation modeling (SEM) approach is employed to disentangle the direct effect of public participation on governance performance from its indirect effect through trust. Moderated multiple regressions (MMR) are conducted to identify the moderating effect of risk perception. The results indicate that public participation is associated with higher perceived quality of family planning services and decreases son preference through the serial mediation effects of trust and perceived quality. Risk perception of gender imbalance magnifies the positive effect of civic autonomy on perceived quality. This paper extends previous research on the governance of gender imbalance and contributes to the literature on the relationship between public participation, trust, risk perception, and governance performance in authoritarian countries.
Combating the Coronavirus Pandemic in Small Schools
Authors: Maněnová Martina , Wolf Janet , Skutil Martin , Vítová Jitka
Published: June 2021

Due to the COVID-19 pandemic, the issue of distance education in primary schools has become a much-discussed topic. It is therefore no surprise that the issues related to it have come to the forefront of many researchers. There is, however, at least one group that has stayed relatively unnoticed, and it is so-called small schools. Thus, we conducted a qualitative study based on the phenomenological approach, searching for answers to our research question: What has been the experience of the directors of small schools with distance education during the pandemic? Our findings offer an in-depth insight into the life of six schools through the eyes of their directors. Semi-structural interviews with school directors helped us reveal three key factors that, in our opinion, had the greatest influence on the form of distance education. These are (1) the factor of ICT competence of all actors, (2) the factor of organization of educational settings, and (3) the factor of the teaching methods and forms used in education. Furthermore, we conclude the result section with a subchapter that captures the positive aspects of distance education as perceived by the addressed school directors.
Heterogeneous Deterioration Process and Risk of Deficiencies of Aging Bridges for Transportation Asset Management
Authors: Han Daeseok
Published: June 2021

The government of the Republic of Korea has set the minimum service level of bridges as Grade B and has defined the risk management level as higher than 95 percent. To achieve this goal, it is necessary to understand the deterioration process and risk of deficiencies for bridges, and these characteristics should be reflected in the management strategy and budget investment plan. To this end, this study developed deterioration models according to the bridge ages to define heterogeneous deterioration characteristics of aging bridges. To build the deterioration models, this study collected and processed bridge diagnosis data for 10 years, and a Bayesian Markov mixed hazard model was introduced. Analysis results showed that the life expectancy of the aging bridges over 30 years was remarkably short, 1/3 of the average life expectancy of the network, and the probability of failure was seven times higher than that of new bridges within 10 years after completion. In addition, the optimal maintenance demand that satisfies a risk management level of 95 percent illustrated that 44.7 percent of the bridges at Grade C should be continuously maintained annually. The results showed that it is urgent to prepare a preemptive response strategy and budget-securing plan for aging bridges, which will rapidly increase to 39% in the next 10 years and 76% in 20 years.
Artificial Intelligence Applied to Evaluate Emissions and Energy Consumption in Commuter Railways: Comparison of Liquefied Natural Gas as an Alternative Fuel to Diesel
Authors: Luque Pablo , Mántaras Daniel A. , Sanchez Luciano
Published: June 2021

At present, there is a common effort to reduce the environmental effect of energy consumption. With this objective, the transportation sector seeks to improve emissions in all its modes. In particular, the rail transport industry is analysing various alternatives for non-electrified lines. These services are mainly carried out with diesel units. As an alternative to diesel fuel, in the present study the use of liquefied natural gas (LNG) in railway traction was analysed. A predictive model was developed and implemented in order to estimate the emissions impact of this fuel on different rail routes or networks. The model was fitted with real data obtained from pilot tests. In these tests, a train with two engines, one diesel and the other LNG, was used. The methodology was applied to evaluate the impact on consumption and emissions of the two fuels on a narrow-gauge commuter line. An improvement was observed in some indicators, while in others there was no clear progress. The conclusions that can be drawn are that CO2 (greenhouse gas) operating emissions are lower in the LNG engine than in the diesel line; CO emissions are lower in the diesel engine and emissions of other pollutants (nitrogen oxide and particles) are higher in the diesel engine by several orders of magnitude.
The Impact of Extreme Events and Climate Change on Agricultural and Fishery Enterprises in Central Vietnam
Authors: Do Van Quang , Phung Mai Lan , Truong Duc Toan , Pham Thi Thanh Trang , Dang Van Thanh , Nguyen The Kien
Published: June 2021

Vietnam is located in the tropical monsoon region and it often faces many types of extreme weather events, especially storms and droughts. In addition to the effect of climate change, extreme weather events have been becoming more complicated and difficult to predict, causing heavy losses to many areas and economic sectors of the country. These problems impose a great threat to the country to achieve its socio-economic targets and sustainable development goals. This study uses a Riparian approach integrated with two-stage Hsiao method using a panel dataset from 2000–2018 to examine the impact of extreme weather events and climate change on the output of agriculture and fishery enterprises in the Central and Central Highlands regions of Vietnam. Findings from the study indicate that extreme weather events and climate change have a negative impact on agriculture and fishery enterprises in the regions. Specifically, the model results show that the value-added loss to agriculture and fishery enterprises as the impact of extreme weather events and climate change may escalate from billion VND 3597.72 to 18,891.2 under different climate change scenarios. The results also indicate the impact of various factors regarding extreme weather events and climate change on the efficiency of enterprises in the study area. Findings from this study provide insights on the impacts of extreme weather events and climate change on value-added of enterprises in the study regions and help to propose appropriate solutions to adapt and mitigate their impacts in the future.
Inner Damping of Water in Conduit of Hydraulic Power Plant
Authors: Himr Daniel , Habán Vladimír , Štefan David
Published: June 2021

The operation of any hydraulic power plant is accompanied by pressure pulsations that are caused by vortex rope under the runner, rotor–stator interaction and various transitions during changes in operating conditions or start-ups and shut-downs. Water in the conduit undergoes volumetric changes due to these pulsations. Compression and expansion of the water are among the mechanisms by which energy is dissipated in the system, and this corresponds to the second viscosity of water. The better our knowledge of energy dissipation, the greater the possibility of a safer and more economic operation of the hydraulic power plant. This paper focuses on the determination of the second viscosity of water in a conduit. The mathematical apparatus, which is described in the article, is applied to data obtained during commissioning tests in a water storage power plant. The second viscosity is determined using measurements of pressure pulsations in the conduit induced with a ball valve. The result shows a dependency of second viscosity on the frequency of pulsations.
The Market Responses to Super Bowl Advertising: The Role of Product Type and Multiple Executions
Authors: Lee Jung-Gyo , Ko Kyung-A
Published: June 2021

This study uses event study analysis to examine the impact of Super Bowl commercials on the stock prices of sponsoring firms by product type and the frequency of ad executions. By examining 272 Super Bowl advertisements from 142 firms that aired from 2010 to 2019, the results show that the execution of Super Bowl advertising was positively associated with excess returns. In particular, the abnormal return for the day after the event represents the largest gain in excess returns over a period of ±10 days around the event day. Further, cumulative average abnormal returns (CAARs) are consistently positive right after the event day. The findings demonstrate that Super Bowl commercials yielded higher returns for low-involvement and hedonic products. The number of ad executions is found to substantially enhance the effectiveness of Super Bowl advertising.
ESG Ratings and Stock Performance during the COVID-19 Crisis
Authors: Engelhardt Nils , Ekkenga Jens , Posch Peter
Published: June 2021

We investigate the association between Environmental, Social, and Governance (ESG) ratings and stock performance during the COVID-19 crisis. Although there is mixed evidence in the literature whether ESG is valuable in times of crisis, we find high ESG-rated European firms to be associated with higher abnormal returns and lower stock volatility. After decomposing ESG into its separate components, we find the social score to be the predominant driver of our results. Further, we argue that ESG is value-enhancing in low-trust countries, and in countries with poorer security regulations and where lower disclosure standards prevail.
A Concise Review on Interlayer Bond Strength in 3D Concrete Printing
Authors: Babafemi Adewumi John , Kolawole John Temitope , Miah Md Jihad , Paul Suvash Chandra , Panda Biranchi
Published: June 2021

Interlayer bond strength is one of the key aspects of 3D concrete printing. It is a well-established fact that, similar to other 3D printing process material designs, process parameters and printing environment can significantly affect the bond strength between layers of 3D printed concrete. The first section of this review paper highlights the importance of bond strength, which can affect the mechanical and durability properties of 3D printed structures. The next section summarizes all the testing and bond strength measurement methods adopted in the literature, including mechanical and microstructure characterization. Finally, the last two sections focus on the influence of critical parameters on bond strength and different strategies employed in the literature for improving the strength via strengthening mechanical interlocking in the layers and tailoring surface as well as interface reactions. This concise review work will provide a holistic perspective on the current state of the art of interlayer bond strength in 3D concrete printing process.
Spreading of Food Deserts in Time and Space: The Case of the City of Nitra (Slovakia)
Authors: Trembošová Miroslava , Jakab Imrich
Published: June 2021

The aim of the article is to evaluate the time availability of food stores for the population permanently residing in the city of Nitra (Slovakia). Parts of the city where poor accessibility has been identified can be described as “food deserts”. In the last two decades, there have been dramatic changes in the retail network in Nitra, as well as extensive housing construction and an aging change in the demographic structure. Therefore, we evaluated the years 2008 and 2019 separately. This made it possible to evaluate the changes in time availability and the number of inhabitants located in individual zones. During the years 2008–2019, the residential zones of the city of Nitra increased by 43.86%, the area of food desert increased by up to 68.78%, and the number of inhabitants endangered by the food desert increased by 1100 residents, i.e., 23.9%. In 2008, 5.51% of Nitra’s residents lived in the food deserts, in approximately twelve years this percentage increased to 7.45% of the population (2019). The proximity to the nearest grocery was in Nitra in 2008 median 504 m, while in 2019 median 623 m. Evaluating the time availability of grocery stores and identifying so-called “food deserts” can be interesting for both the city’s residents and the business community, especially for potential developers. It can also be used effectively in the spatial planning process and in the rational management of complex territorial development, as well as in local politics. Given the character of the city of Nitra, it can be assumed that the acquired knowledge can be extrapolated to other post-socialist cities of a similar size and hierarchical level.
Microstructure of Structural Lightweight Concrete Incorporating Coconut Shell as a Partial Replacement of Brick Aggregate and Its Influence on Compressive Strength
Authors: Bari Hamidul , Safiuddin Md. , Salam Md. Abdus
Published: June 2021

In this study, coconut shell aggregate (CSA) was used in brick aggregate concrete (BAC) to produce structural lightweight concrete. Various BACs containing CSA (CSBACs) were prepared based on the volumetric mix ratio of 1:1.5:3 (cement:fine aggregate:coarse aggregate). CSA was used substituting 0−15% of brick aggregate (BA) by weight. The concrete mixes were designed based on the weight-based water to cement (w/c) ratios of 0.45, 0.50, and 0.55. All the freshly mixed concretes were tested for their workability with respect to slump. In addition, the freshly mixed concretes made with the w/c ratio of 0.50 were examined for their wet density and air content. The hardened concretes were tested for their dry density, compressive strength, and microstructural characteristics (e.g., microcrack, micropore, fissure). The microstructure of CSBACs was investigated by a scanning electron microscope (SEM). In addition, the fissure width between the cement paste and CSA was measured from the SEM images using “ImageJ” software. The correlation between the compressive strength and fissure width of CSBAC was also examined. Test results showed that the air content of CSBACs including 5–15% CSA was higher than that of the control concrete (0% CSA). In addition, the density and compressive strength of concrete decreased with the increased CSA content. Above all, the most interesting finding of this study was the presence of fissures in the interfacial transition zone between the cement paste and CSA of CSBAC. The fissure width gradually increased with the increase in CSA content and thus decreased the compressive strength of concrete. However, the fissure width decreased with the increased curing age of concrete and therefore the compressive strength of CSBAC was enhanced at later ages. Moreover, a good correlation between the compressive strength and fissure width of CSBAC was observed in this study.