bluuebunny/crossref_metadata_2025 huggingface dataset:
Protective Face Mask Filter Capable of Inactivating SARS-CoV-2, and Methicillin-Resistant Staphylococcus aureus and Staphylococcus epidermidis
Authors: Martí Miguel , Tuñón-Molina Alberto , Aachmann Finn , Muramoto Yukiko , Noda Takeshi , Takayama Kazuo , Serrano-Aroca Ángel
Published: January 2021

Face masks have globally been accepted to be an effective protective tool to prevent bacterial and viral transmission, especially against indoor aerosol transmission. However, commercial face masks contain filters that are made of materials that are not capable of inactivating either SARS-CoV-2 or multidrug-resistant bacteria. Therefore, symptomatic and asymptomatic individuals can infect other people even if they wear them because some viable viral or bacterial loads can escape from the masks. Furthermore, viral or bacterial contact transmission can occur after touching the mask, which constitutes an increasing source of contaminated biological waste. Additionally, bacterial pathogens contribute to the SARS-CoV-2-mediated pneumonia disease complex, and their resistance to antibiotics in pneumonia treatment is increasing at an alarming rate. In this regard, herein, we report the development of a non-woven face mask filter fabricated with a biofunctional coating of benzalkonium chloride that is capable of inactivating more than 99% of SARS-CoV-2 particles in one minute of contact, and the life-threatening methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis (normalized antibacterial halos of 0.52 ± 0.04 and 0.72 ± 0.04, respectively). Nonetheless, despite the results obtained, further studies are needed to ensure the safety and correct use of this technology for the mass production and commercialization of this broad-spectrum antimicrobial face mask filter. Our novel protective non-woven face mask filter would be useful for many healthcare workers and researchers working in this urgent and challenging field.
Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications
Authors: Riehle Natascha , Athanasopulu Kiriaki , Kutuzova Larysa , Götz Tobias , Kandelbauer Andreas , Tovar Günter E. M. , Lorenz Günter
Published: January 2021

The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol−1), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H12MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H12MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H12MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.
On the Use of Persian Gum for the Development of Antiviral Edible Coatings against Murine Norovirus of Interest in Blueberries
Authors: Sharif Niloufar , Falcó Irene , Martínez-Abad Antonio , Sánchez Gloria , López-Rubio Amparo , Fabra María José
Published: January 2021

In the last decades, berries have been identified as important vehicles for the transmission of foodborne viruses and different strategies are being explored to eliminate or reduce viral contamination in these fruits. The aim of this work was to develop novel edible coatings with antiviral properties for inactivating and reducing murine norovirus (MNV). Firstly, the effect of gelatin (G) addition on Persian gum (PG) films was studied in terms of microstructural, mechanical, optical, and water barrier properties. The following PG:G ratios were considered: 100:0, 75:25, 50:50, 25:75, and 0:100. Microstructure analysis revealed the compatibility of both hydrocolloids since no phase separation was observed. The addition of G to PG films provided stiffer and more deformable films than pure PG, with lower water vapor permeability values. Specifically, films prepared with 50:50 PG:G ratio presented better mechanical and barrier performance. Interestingly, pure PG showed antiviral activity on murine norovirus, probably due to the presence of some impurities (mainly tannins). Adding allyl isothiocyanate (AITC) enhanced the PG antiviral activity at refrigerated temperatures in blueberries, not being affected by the AITC concentration. This effect was not observed at ambient temperature, probably due to the volatilization of AITC.
Pyrolysis of Polystyrene Waste: A Review
Authors: Maafa Ibrahim
Published: January 2021

The manufacturing of polystyrene around the globe has escalated in the past years due to its huge applications in various areas. The perpetual market needs of polystyrene led the polystyrene wastes accretion in the landfill causing environmental deterioration. The soaring need for polystyrene also led to the exhaustion of petroleum, a non-renewable energy source, as polystyrene is a petroleum-derived product. Researchers from around the world have discovered a few techniques to take care of the polystyrene scraps, namely recycling and energy recovery techniques. Nevertheless, there are demerits involved with recycling techniques, such as they call for huge labor expenses in the separation process and cause water pollution, thereby decreasing the process sustainability. Owing to these demerits, the researchers have focused their attention on the energy recovery technique. Since petroleum is the main ingredient of polystyrene synthesis, the restoration of liquid oil from polystyrene via the pyrolysis method is a promising technique as the recovered oil has greater calorific value as compared to commercially available fuel. The present paper surveys the pyrolysis technique for polystyrene and the important process parameters that control the end product, like oil, gas, and char. The chief process parameters that are discussed in this review paper include the type of reactors, temperature, residence time, pressure, catalyst types, type of fluidizing gases, and their flow rate. A more recent technique of utilizing a solvent to perform pyrolysis and the effect of various process conditions on the product yield have been discussed. Apart from this, various outlooks to optimize the liquid oil recovery from polystyrene are also reviewed.
Magnetic Solid-Phase Extraction of Cadmium Ions by Hybrid Self-Assembled Multicore Type Nanobeads
Authors: Buema Gabriela , Borhan Adrian Iulian , Herea Daniel Dumitru , Stoian George , Chiriac Horia , Lupu Nicoleta , Roman Tiberiu , Pui Aurel , Harja Maria , Gherca Daniel
Published: January 2021

Novel hybrid inorganic CoFe2O4/carboxymethyl cellulose (CMC) polymeric framework nanobeads-type adsorbents with tailored magnetic properties were synthesized by a combination of coprecipitation and flash-cooling technology. Precise self-assembly engineering of their shape and composition combined with deep testing for cadmium removal from wastewater are investigated. The development of a single nanoscale object with controllable composition and spatial arrangement of CoFe2O4 (CF) nanoparticles in carboxymethyl cellulose (CMC) as polymeric matrix, is giving new boosts to treatments of wastewaters containing heavy metals. The magnetic nanobeads were characterized by means of scanning electron microscopy (SEM), powder X-ray diffraction analysis (XRD), thermogravimetric analysis (TG), and vibrational sample magnetometer (VSM). The magnetic properties of CF@CMC sample clearly exhibit ferromagnetic nature. Value of 40.6 emu/g of saturation magnetization would be exploited for magnetic separation from aqueous solution. In the adsorptions experiments the assessment of equilibrium and kinetic parameters were carried out by varying adsorbent dosage, contact time and cadmium ion concentration. The kinetic behavior of adsorption process was best described by pseudo-second-order model and the Langmuir isotherm was fitted best with maximum capacity uptake of 44.05 mg/g.
Are Structurally Modified Galactomannan Derivatives Biologically Active?
Authors: Geronço Maurycyo Silva , da Silveira Ramos Igor Frederico , da Silva Filho Edson Cavalcanti , dos Santos Rizzo Márcia , Ribeiro Alessandra Braga , da Costa Marcilia Pinheiro
Published: January 2021

Galactomannans are versatile macromolecules with broad industrial potential. The influence of changes in the chemical structures and respective bioactivities of these polysaccharides have been extensively studied. The derivatives obtained by sulfation, complexation, and phosphorylation are the most studied biological properties in galactomannans. The derivatives obtained have shown several pharmacological activities such as antiviral, antimicrobial, anticoagulant, fibrinolytic, chemopreventive, anticancer, antioxidant, chondroprotective, analgesic, immunomodulatory, and antileishmanial. Considering the relevance of these studies, we aim to provide an overview of studies that apply galactomannan modification or derivatization strategies to improve their properties for applications in the biomedical area. We identified the success of most modified galactomannans for pharmacological purposes. However, some studies found loss of bioactivity of the original polysaccharide after chemical changes to its original structures.
Investigation of Electrochemical Processes in Solid Oxide Fuel Cells by Modified Levenberg–Marquardt Algorithm: A New Automatic Update Limit Strategy
Authors: Žic Mark , Fajfar Iztok , Subotić Vanja , Pereverzyev Sergei , Kunaver Matevž
Published: January 2021

Identification of ongoing processes in solid oxide fuel cells (SOFC) enables both optimizing the operating environment and prolonging the lifetime of SOFC. The Levenberg–Marquardt algorithm (LMA) is commonly used in the characterization of unknown electrochemical processes within SOFC by extracting equivalent electrical circuit (EEC) parameter values from electrochemical impedance spectroscopy (EIS) data. LMA is an iteration optimization algorithm regularly applied to solve complex nonlinear least square (CNLS) problems. The LMA convergence can be boosted by the application of an ordinary limit strategy, which avoids the occurrence of off-limit values during the fit. However, to additionally improve LMA descent properties and to discard the problem of a poor initial parameters choice, it is necessary to modify the ordinary limit strategy. In this work, we designed a new automatic update (i.e., adaptive) limit strategy whose purpose is to reduce the impact of a poor initial parameter choice. Consequently, the adaptive limit strategy was embedded in a newly developed EIS fitting engine. To demonstrate that the new adaptive (vs. ordinary) limit strategy is superior, we used it to solve several CNLS problems. The applicability of the adaptive limit strategy was also validated by analyzing experimental EIS data collected by using industrial-scale SOFCs.
Rapid and Green Preparation of Multi-Branched Gold Nanoparticles Using Surfactant-Free, Combined Ultrasound-Assisted Method
Authors: Huynh Phat Trong , Nguyen Giang Dang , Thi Le Tran Khanh , Minh Ho Thu , Lam Vinh Quang , Ngo Thanh Vo Ke
Published: January 2021

The conventional seed-mediated preparation of multi-branched gold nanoparticles uses either cetyltrimethylammonium bromide or sodium dodecyl sulfate. However, both surfactants are toxic to cells so they have to be removed before the multi-branched gold nanoparticles can be used in biomedical applications. This study describes a green and facile method for the preparation of multi-branched gold nanoparticles using hydroquinone as a reducing agent and chitosan as a stabilizer, through ultrasound irradiation to improve the multi-branched shape and stability. The influence of pH, mass concentration of chitosan, hydroquinone concentration, as well as sonication conditions such as amplitude and time of US on the growth of multi-branched gold nanoparticles, were also investigated. The spectra showed a broad band from 500 to over 1100 nm, an indication of the effects of both aggregation and contribution of multi-branches to the surface plasmon resonance signal. Transmission electron microscopy measurements of GNS under optimum conditions showed an average core diameter of 64.85 ± 6.79 nm and 76.11 ± 14.23 nm of the branches of multi-branched particles. Fourier Transfer Infrared Spectroscopy was employed to characterize the interaction between colloidal gold nanoparticles and chitosan, and the results showed the presence of the latter on the surface of the GNS. The cytotoxicity of chitosan capped GNS was tested on normal rat fibroblast NIH/3T3 and normal human fibroblast BJ-5ta using MTT assay concentrations from 50–125 µg/mL, with no adverse effect on cell viability.
Bioactive Compounds Produced by the Accompanying Microflora in Bulgarian Yoghurt
Authors: Ivanov Ivan , Petrov Kaloyan , Lozanov Valentin , Hristov Iassen , Wu Zhengjun , Liu Zhenmin , Petrova Penka
Published: January 2021

Bulgarian yoghurt is associated with health benefits and longevity of consumers. The specific microflora producing bioactive metabolites is responsible for this effect. The present study examines the biodiversity in four homemade yoghurts from regions containing endemic microflora. Metagenome sequencing indicated Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus were predominant in all samples. In addition, yoghurts contained accompanying lactic acid bacteria (LAB) including Lacticaseibacillus paracasei, Lb. helveticus, Limosilactobacillus fermentum, Lb. rhamnosus, Lactococcus lactis, Pediococcus acidilactici, Leuconostoc mesenteroides, and Leuc. pseudomesenteroides. A negligible amount of pollutant strains was found. Twenty-four LAB strains were isolated from the yoghurts and identified. Lb. delbrueckii subsp. bulgaricus strains were genotyped by randomly amplified polymorphic DNA–PCR (RAPD), multi-locus sequence typing (MLST), and pulse field gel electrophoresis (PFGE), which demonstrated their uniqueness and non-commercial origin. To estimate the bioactive metabolites produced by the accompanying microflora, yoghurts fermented by single LAB strains were analyzed using liquid chromatography and mass spectrometry (LC-MS). The fermented samples contained large amounts of free essential amino acids (arginine, citrulline, tryptophan, lysine, and histidine), the neuroprotector indole-3-propionic acid (IPA), and significant quantities of the cyclic antimicrobial peptides cyclo(phenylalanyl-prolyl) and cyclo(leucyloprolyl). The disclosure of these special qualities draws attention to the accompanying microflora as a source of potential probiotic strains that can fortify the yoghurts’ content with bioactive compounds.
Qualitative Analysis of the Perception of Company Managers in Knowledge Management in the Maintenance Activity in the Era of Industry 4.0
Authors: Cárcel-Carrasco Javier , Gómez-Gómez Consuelo
Published: January 2021

In industrial maintenance activity, very sophisticated technical and human factors are needed to achieve the great process or service that the company provides, with a large dose of knowledge based on the personal experience of maintenance technicians. However, the management and application of knowledge in this activity is often relegated to a third level (or simply forgotten). The aim of this study is to identify, classify and prioritize the different barriers and facilitators that can be found in maintenance organizations of the company in reference to knowledge management in strategic maintenance activities, and what competitive advantages could be used for their appropriate introduction in the company. For this, qualitative techniques have been used through a field study and observation, as well as semi-structured interviews between company directors and maintenance managers of first-level companies in various sectors (industrial or services), to draw conclusions on the application of knowledge management techniques which help to determine the principles of a company that wants to face a knowledge management project within the area of maintenance engineering.
Global Stability Analysis of a Bioreactor Model for Phenol and Cresol Mixture Degradation
Authors: Dimitrova Neli , Zlateva Plamena
Published: January 2021

We propose a mathematical model for phenol and p-cresol mixture degradation in a continuously stirred bioreactor. The model is described by three nonlinear ordinary differential equations. The novel idea in the model design is the biomass specific growth rate, known as sum kinetics with interaction parameters (SKIP) and involving inhibition effects. We determine the equilibrium points of the model and study their local asymptotic stability and bifurcations with respect to a practically important parameter. Existence and uniqueness of positive solutions are proved. Global stabilizability of the model dynamics towards equilibrium points is established. The dynamic behavior of the solutions is demonstrated on some numerical examples.
Numerical Analyses of Heterogeneous CLC Reaction and Transport Processes in Large Oxygen Carrier Particles
Authors: Huo Guanping , Guo Xueyan
Published: January 2021

Heterogeneous chemical looping combustion (CLC) reactions and conjugate transports in large oxygen carrier particles were numerically investigated with computational fluid dynamics (CFD) approaches, in which a simplified noncatalytic reaction model was implemented for reducing intraparticle modelling computation. Volumic gas-solid reactions were treated as surface reactions based on the equivalent internal surface in the particle model. In large porous particles such as fixed bed CLC reactors, the heterogeneous reactions are often limited by intraparticle diffusion. Comprehensive analyses were conducted on transports across the particle surface and their influences on reactions inside the single particles. A threshold Reynolds number of external convections was found for the enhancement of intraparticle reactions. The heterogeneous reactions, intraparticle diffusions and interstitial transports in a fixed bed CLC reactor randomly packed with 597 spheres were thoroughly analysed with the same numerical approaches. Comprehensive insights of the temporal evolution and spatial distribution of scalars in the packed bed reactor were presented.
Abrasive Wear Behavior of CNT-Filled Unidirectional Kenaf–Epoxy Composites
Authors: Sapiai Napisah , Jumahat Aidah , Jawaid Mohammad , Santulli Carlo
Published: January 2021

Kenaf (Hibiscus Cannabinus) fibers have received significant attention for replacing the usage of synthetic fibers, especially glass fiber, in the fabrication of fiber-reinforced polymer (FRP) composites. The aim of this research was to study the change in wear behavior of kenaf-epoxy fiber composites by filling them with multiwall carbon nanotubes (MWCNT). In particular, the effect of untreated MWCNT (PMWCNT), acid-treated MWCNT (AMWCNT), and silane-treated MWCNT (SMWCNT) was studied, using three different MWCNT loadings, i.e., 0.5, 0.75, and 1 wt.%. The abrasive wear test was conducted to measure the wear properties of the composites. A thermal infrared camera was also used to measure the punctual contact temperature during the abrasive wear test, while the abraded surfaces were analyzed using the stereomicroscope. Starting from the considerable reduction of wear rate with the introduction of kenaf fibers, it was observed that PMWCNT provided some further, yet modest, reduction of wear rate only at the higher loadings. In contrast, the inclusion of AMWCNT proved to increase the specific wear rate of the epoxy-kenaf composites, an effect worsened at higher loadings. This may be due to the weakened interfacial bonding between the AMWCNT and epoxy. On the other hand, the presence of SMWCNT improved the interfacial bonding between CNT and epoxy, as shown by an increase in contact temperature. However, the increase in bonding strength was stipulated to have caused the rougher worn debris, thus inducing a three-body abrasive wear effect.
High Yield Super-Hydrophobic Carbon Nanomaterials Using Cobalt/Iron Co-Catalyst Impregnated on Powder Activated Carbon
Authors: Betar Bashir O. , Alsaadi Mohammed A. , Chowdhury Zaira Z. , Aroua Mohamed K. , Mjalli Farouq S. , Niazi MD Mourad
Published: January 2021

Synthesis of super-hydrophobic carbonaceous materials is gaining a broader interest by the research community due to its versatile application in separation processes, special coating technologies, and membrane distillation. Carbon nanomaterials (CNMs) may exhibit stable super-hydrophobic character due to their unique physio-chemical features which can be further controlled based on customer requirements by optimizing the process variables. This study deals with the application of a bimetallic catalyst composed of iron (Fe) and cobalt (Co) to synthesize CNMs from powder activated carbon as a precursor. The process parameters were optimized to ensure super-hydrophobic surfaces. Chemical vapor deposition was utilized for the growth of carbon nanomaterials. The impact of input variables on the desired output of yield and contact angle was analyzed. The chemical vapor deposition process was optimized using the response surface methodology based on Box-Behnken design. The proportion of the catalysts and reaction time were the three input explanatory variables whereas the desired response variables were selected as the carbon yield (CY) and contact angle (CA). The synthesized super-hydrophobic materials were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, thermogravimetric analysis (TGA), and contact angle analysis. The comprehensive statistical study of the results led to a significant model and optimization. The highest CY (351%) and CA (173°) were obtained at the optimal loading of 2.5% Fe and 2% Mo with a reaction time of 60 min. The images obtained from FESEM and TEM revealed the presence of two types of CNMs including carbon nanofibers and multiwall carbon nanotubes. Thermogravimetric analysis was carried out to observe the temperature degradation profile of the synthesized sample. Raman spectroscopic analysis was also used to observe the proportion of ordered and disordered carbon content inside the synthesized samples. The improved catalytic super-hydrophobic carbon nanostructured materials production process proposed by this study assures the stability and high yield of the product.
Polymeric Films Containing Tenoxicam as Prospective Transdermal Drug Delivery Systems: Design and Characterization
Authors: Ciurba Adriana , Antonoaea Paula , Todoran Nicoleta , Rédai Emőke , Vlad Robert Alexandru , Tătaru Anamaria , Muntean Daniela-Lucia , Bîrsan Magdalena
Published: January 2021

The administration of drugs via transdermal therapeutic systems has become an attractive form of therapeutic approach, considering its advantages and the high patient compliance achieved, making them a viable alternative, especially in the treatment of chronic diseases. The purpose of our study was the development of polymer-based films containing tenoxicam (TX) and the analysis of dissolution kinetics. Auxiliary substances represent an important part of pharmaceutical forms, so during the first stage, TX and excipient compatibility were verified. Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analyses were performed on TX and on physical mixtures of TX-HPMCE5 and TX-HPMC15kcP. Three polymeric films of TX (TX1, TX2, and TX3) were prepared using a solvent evaporation technique. Release studies were done at 32 °C ± 1 °C with a Franz diffusion cell. The results of the DSC and FT-IR analyses demonstrated the compatibility of the active substance with the two matrix-forming polymers. The results obtained in the release studies of TX from the proposed polymeric films suggested a pH-dependent behavior in all three polymeric films. At pH 5.5, flux values were between 8.058 ± 0.125 μg·cm−2·h−1 and 10.850 ± 0.380 μg·cm−2·h−1; and at pH 7.4, between 10.990 ± 0.2.490 μg·cm−2·h−1 and 53.140 ± 0.196 μg·cm−2·h−1. The Korsmeyer–Peppas model described a non-Fickian transport mechanism. The n values varied between 0.63–0.7 at pH 5.5 and 0.73–0.86 at pH 7.4, which suggested a diffusion depending on the matrix hydration and polymer relaxation.
Past, Present and Future of Prosthesis: 2020 Upgrade
Authors: Cicciù Marco
Published: January 2021

The scientific journal Prosthesis (ISSN 2673-1592) had its first issue published in 2019 thanks to the publisher, MDPI [...]
The Influence of Regulatory Focus on Media Choice in Interpersonal Conflicts
Authors: Tretter Stefan , Diefenbach Sarah
Published: January 2021

People’s choices of (electronic) communication channels are central to the quality of communication—and sometimes detrimental to their actual communication goals. However, while factors influencing media choice are abundant, potential means to intentionally influence these choices are scarce within computer-mediated communication research. We explore the role of regulatory focus as one possible factor to understand and influence media choice in interpersonal conflicts. Regulatory focus theory proposes two motivational systems, promotion (i.e., needs for nurturance and growth) and prevention (i.e., needs for safety and security), that account for differences in preferred strategies for goal-pursuit. In a vignette-based study, we manipulated the situational regulatory focus (promotion or prevention) and surveyed participants’ preferred media choice for a hypothetical conflict scenario. Our results show that the induction of a dominant prevention focus (vs. promotion focus) leads to a shift in preference towards leaner communication media and channels that establish a higher subjective buffer between sender and receiver (e.g., text-messaging over calling). We elaborate on how these findings contribute to the understanding of media choice in interpersonal conflicts and point out potential ways to influence behavior through the design of communication technologies. Limitations of the present study and future research opportunities are discussed.
Dating of the Lower Pleistocene Vertebrate Site of Tsiotra Vryssi (Mygdonia Basin, Greece): Biochronology, Magnetostratigraphy, and Cosmogenic Radionuclides
Authors: Konidaris George , Kostopoulos Dimitris , Maron Matteo , Schaller Mirjam , Ehlers Todd , Aidona Elina , Marini Mattia , Tourloukis Vangelis , Muttoni Giovanni , Koufos George , Harvati Katerina
Published: January 2021

Background and scope: The late Villafranchian large mammal age (~2.0–1.2 Ma) of the Early Pleistocene is a crucial interval of time for mammal/hominin migrations and faunal turnovers in western Eurasia. However, an accurate chronological framework for the Balkans and adjacent territories is still missing, preventing pan-European biogeographic correlations and schemes. In this article, we report the first detailed chronological scheme for the late Villafranchian of southeastern Europe through a comprehensive and multidisciplinary dating approach (biochronology, magnetostratigraphy, and cosmogenic radionuclides) of the recently discovered Lower Pleistocene vertebrate site Tsiotra Vryssi (TSR) in the Mygdonia Basin, Greece. Results: The minimum burial ages (1.88 ± 0.16 Ma, 2.10 ± 0.18 Ma, and 1.98 ± 0.18 Ma) provided by the method of cosmogenic radionuclides indicate that the normal magnetic polarity identified below the fossiliferous layer correlates to the Olduvai subchron (1.95–1.78 Ma; C2n). Therefore, an age younger than 1.78 Ma is indicated for the fossiliferous layer, which was deposited during reverse polarity chron C1r. These results are in agreement with the biochronological data, which further point to an upper age limit at ~1.5 Ma. Overall, an age between 1.78 and ~1.5 Ma (i.e., within the first part of the late Villafranchian) is proposed for the TSR fauna. Conclusions: Our results not only provide age constraints for the local mammal faunal succession, thus allowing for a better understanding of faunal changes within the same sedimentary basin, but also contribute to improving correlations on a broader scale, leading to more accurate biogeographic, palaeoecological, and taphonomic interpretations.
Between Dualism and Immanentism Sacramental Ontology and History
Authors: Beltramini Enrico
Published: January 2021

How to deal with religious ideas in religious history (and in history in general) has recently become a matter of discussion. In particular, a number of authors have framed their work around the concept of ‘sacramental ontology,’ that is, a unified vision of reality in which the secular and the religious come together, although maintaining their distinction. The authors’ choices have been criticized by their fellow colleagues as a form of apologetics and a return to integralism. The aim of this article is to provide a proper context in which to locate the phenomenon of sacramental ontology. I suggest considering (1) the generation of the concept of sacramental ontology as part of the internal dialectic of the Christian intellectual world, not as a reaction to the secular; and (2) the adoption of the concept as a protection against ontological nihilism, not as an attack on scientific knowledge.
On the Market-Consistent Valuation of Participating Life Insurance Heterogeneous Contracts under Longevity Risk
Authors: Bacinello Anna Rita , Chen An , Sehner Thorsten , Millossovich Pietro
Published: January 2021

The purpose of this paper is to conduct a market-consistent valuation of life insurance participating liabilities sold to a population of partially heterogeneous customers under the joint impact of biometric and financial risk. In particular, the heterogeneity between groups of policyholders stems from their offered minimum interest rate guarantees and contract maturities. We analyse the effects of these features on the company’s insolvency while embracing the insurer’s goal to achieve the same expected return for different cohorts of policyholders. Within our extensive numerical analyses, we determine the fair participation rates and other key figures, and discuss the implications for the stakeholders, taking account of various degrees of conservativeness of the insurer when pricing the contracts.
Pattern of Turbidity Change in the Middle Reaches of the Yarlung Zangbo River, Southern Tibetan Plateau, from 2007 to 2017
Authors: Shen Ming , Wang Siyuan , Li Yingkui , Tang Maofeng , Ma Yuanxu
Published: January 2021

Turbidity is an important indicator of riverine conditions, especially in a fragile environment such as the Tibetan Plateau. Remote sensing, with the advantages of large-scale observations, has been widely applied to monitor turbidity change in lakes and rivers; however, few studies have focused on turbidity change of rivers on the Tibetan Plateau. We investigated the pattern of turbidity change in the middle reaches of the Yarlung Zangbo River, southern Tibetan Plateau, based on multispectral satellite imagery and in situ measurements. We developed empirical models from in situ measured water leaving reflectance and turbidity, and applied the best performed s-curve models on satellite imagery from Sentinel-2, Landsat 8, and Landsat 5 to derive turbidity change in 2007–2017. Our results revealed an overall decreasing spatial trend from the upper to lower streams. Seasonal variations were observed with high turbidity from July to September and low turbidity from October to May. Annual turbidity showed a temporally slightly declining trend from 2007 to 2017. The pattern of turbidity change is affected by the confluence of tributaries and the changes in precipitation and vegetation along the river. These findings provide important insights into the responses of riverine turbidity to climate and environmental changes on the Tibetan Plateau.
The Spatial-Temporal Distribution of GOCI-Derived Suspended Sediment in Taiwan Coastal Water Induced by Typhoon Soudelor
Authors: Chau Pham Minh , Wang Chi-Kuei , Huang An-Te
Published: January 2021

This paper discusses the use of a Geostationary Ocean Color Imager (GOCI) to monitor the spatial–temporal distribution of suspended sediment (SS) along the coastal waters of northern Taiwan which was affected by Typhoon Soudelor from 8 to 10 August 2015. High temporal resolution satellite images derived from GOCI were processed to generate four-day average images of SS for pre- and post-typhoon periods. By using these four-day average images, characteristics of SS along the north of Taiwan coastal water can be tracked. The results show that SS concentration increased in the four-day average image immediately after the typhoon (11–14 August), and then decreased in the four-day average image 9 to 12 days after the typhoon (19–22 August). The mouths of the Dajia River and Tamsui River were hotspots of SS, ranging from 9 to 15 g/m3 during the two post-typhoon periods. Moreover, the maximum suspended sediment (SSmax) and its corresponding time (tmax) can be computed using GOCI hourly images for the post-typhoon period from 08:30 on 11 August to 08:30 on 22 August. The results show that SSmax occurred in the west coastal water within 4 days post-typhoon, and SSmax occurred in the east coastal water 9 to 12 days post-typhoon. Furthermore, an exponential decay model was used to compute the time when 90% of typhoon-induced SS was dissipated after Typhoon Soudelor (t90). It was found that t90 in the mouths of the Tamsui River and Heping River was the longest among all coastal waters of our study area, with a range of 360–480 h. River discharge and ocean currents with suspended sediment concentration are discussed.
Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network
Authors: Wang He , Yang Jingsong , Zhu Jianhua , Ren Lin , Liu Yahao , Li Weiwei , Chen Chuntao
Published: January 2021

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.
A Preliminary Study of Wave Energy Resource Using an HF Marine Radar, Application to an Eastern Southern Pacific Location: Advantages and Opportunities
Authors: Mundaca-Moraga Valeria , Abarca-del-Rio Rodrigo , Figueroa Dante , Morales James
Published: January 2021

As climate change is of global concern, the electric generation through fossil fuel is progressively shifted to renewable energies. Among the renewables, the most common solar and wind, the wave energy stands for its high-power density. Studies about wave energy resource have been increasing over the years, especially in coastal countries. Several research investigations have assessed the global wave power, with higher values at high latitudes. However, to have a precise assessment of this resource, the measurement systems need to provide a high temporal and spatial resolution, and due to the lack of in-situ measurements, the way to estimate this value is numerical. Here, we use a high-frequency radar to estimate the wave energy resource in a nearshore central Chile at a high resolution. The study focuses near Concepción city (36.5° S), using a WERA (WavE RAdar) high frequency (HF) radar. The amount of annual energy collected is calculated. Analysis of coefficient of variation (COV), seasonal variability (SV), and monthly variability (MV) shows the area’s suitability for installing a wave energy converter device due to a relatively low variability and the high concentration of wave power obtained. The utility of HF radars in energy terms relies on its high resolution, both temporal and spatial. It can then compare the location of interest within small areas and use them as a complement to satellite measurements or numerical models, demonstrating its versatility.
Spatial Temporal Analysis of Traffic Patterns during the COVID-19 Epidemic by Vehicle Detection Using Planet Remote-Sensing Satellite Images
Authors: Chen Yulu , Qin Rongjun , Zhang Guixiang , Albanwan Hessah
Published: January 2021

The spread of the COVID-19 since the end of 2019 has reached an epidemic level and has quickly become a global public health crisis. During this period, the responses for COVID-19 were highly diverse and decentralized across countries and regions. Understanding the dynamics of human mobility change at high spatial temporal resolution is critical for assessing the impacts of non-pharmaceutical interventions (such as stay-at-home orders, regional lockdowns and travel restrictions) during the pandemic. However, this requires collecting traffic data at scale, which is time-consuming, cost-prohibitive and often not available (e.g., in underdeveloped countries). Therefore, spatiotemporal analysis through processing periodical remote-sensing images is very beneficial to enable efficient monitoring at the global scale. In this paper, we present a novel study that utilizes high temporal Planet multispectral images (from November 2019 to September 2020, on average 7.1 days of frequency) to detect traffic density in multiple cities through a proposed morphology-based vehicle detection method and evaluate how the traffic data collected in such a manner reflect mobility pattern changes in response to COVID-19. Our experiments at city-scale detection, demonstrate that our proposed vehicle detection method over this 3 m resolution data is able to achieve a detection level at an accuracy of 68.26% in most of the images, and the observations’ trends coincide with existing public data of where available (lockdown duration, traffic volume, etc.), further suggesting that such high temporal Planet data with global coverage (although not with the best resolution), with well-devised detection algorithms, can sufficiently provide traffic details for trend analysis to better facilitate informed decision making for extreme events at the global level.
Hindcast and Near Real-Time Monitoring of Green Macroalgae Blooms in Shallow Coral Reef Lagoons Using Sentinel-2: A New-Caledonia Case Study
Authors: Brisset Maële , Van Wynsberge Simon , Andréfouët Serge , Payri Claude , Soulard Benoît , Bourassin Emmanuel , Gendre Romain Le , Coutures Emmanuel
Published: January 2021

Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and types of correction applied to reflectance data, the spectral indices explained between 1 and 64.9% of variance. The models providing the best statistical fit were used to revisit the algal dynamics using Sentinel-2 data from January 2017 to December 2019, through two image segmentation approaches: unsupervised and supervised. The latter accurately reproduced the two algal blooms that occurred in the area in 2018. This paper demonstrates that Sentinel-2 data can be an effective source to hindcast and monitor the dynamics of green algae in shallow lagoons.
Estimating Artificial Impervious Surface Percentage in Asia by Fusing Multi-Temporal MODIS and VIIRS Nighttime Light Data
Authors: Li Fanggang , Li Erzhu , Zhang Ce , Samat Alim , Liu Wei , Li Chunmei , Atkinson Peter M.
Published: January 2021

Impervious surfaces have important effects on the natural environment, including promoting hydrological run-off and impeding evapotranspiration, as well as increasing the urban heat island effect. Obtaining accurate and timely information on the spatial distribution and dynamics of urban surfaces is, thus, of paramount importance for socio-economic analysis, urban planning, and environmental modeling and management. Previous studies have indicated that the fusion of multi-source remotely sensed imagery can increase the accuracy of prediction for impervious surface information across large areas. However, the majority of them are limited to the use of specific data sources to construct a few features with which it can be challenging to characterize adequately the variation in impervious surfaces over large areas. Thus, impervious surface maps are often presented with high uncertainty. In response to this problem, we proposed the use of multi-temporal MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime light data to construct a more general and robust feature set for large-area artificial impervious surface percentage (AISP) prediction. Three fusion methods were proposed for application to multi-temporal MODIS surface reflectance product (MOD09A1) and Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) Day/Night Band (DNB) data to construct three different types of features: spectral features, index features (band calculations), and fusion features. These features were then used as variables in a random-forest-based AISP prediction model. The model was fitted to China and then applied to predict AISP across Asia. Fifteen typical cities from different regions of Asia were selected to assess the accuracy of the prediction model. The use of multi-temporal MODIS and VIIRS DNB data was found to significantly increase the accuracy of prediction for large-area AISP. The feature set constructed in this research was demonstrated to be suitable for large-area AISP prediction, and the random forest model based on optimization of the selected features achieved the highest accuracy, amongst benchmarks, with testing R2 of 0.690, and testing RMSE of 0.044 in 2018, respectively. In addition, to further test the performance of the proposed method, three existing impervious products (GAIA, HBASE, and NUACI) were used to compare quantitatively. The results showed that the predicted AISP achieved superior performance in comparison with others in some areas (e.g., arid areas and cloudy areas).
A Novel Four-Stage Method for Vegetation Height Estimation with Repeat-Pass PolInSAR Data via Temporal Decorrelation Adaptive Estimation and Distance Transformation
Authors: Xing Cheng , Zhang Tao , Wang Hongmiao , Zeng Liang , Yin Junjun , Yang Jian
Published: January 2021

Vegetation height estimation plays a pivotal role in forest mapping, which significantly promotes the study of environment and climate. This paper develops a general forest structure model for vegetation height estimation using polarimetric interferometric synthetic aperture radar (PolInSAR) data. In simple terms, the temporal decorrelation factor of the random volume over ground model with volumetric temporal decorrelation (RVoG-vtd) is first modeled by random motions of forest scatterers to solve the problem of ambiguity. Then, a novel four-stage algorithm is proposed to improve accuracy in forest height estimation. In particular, to compensate for the temporal decorrelation mainly caused by changes between multiple observations, one procedure of temporal decorrelation adaptive estimation via Expectation-Maximum (EM) algorithm is added into the novel method. On the other hand, to extract the features of amplitude and phase more effectively, in the proposed method, we also convert Euclidean distance to a generalized distance for the first time. Assessments of different algorithms are given based on the repeat-pass PolInSAR data of Gabon Lope Park acquired in AfriSAR campaign of German Aerospace Center (DLR). The experimental results show that the proposed method presents a significant improvement of vegetation height estimation accuracy with a root mean square error (RMSE) of 6.23 m and a bias of 1.28 m against LiDAR heights, compared to the results of the three-stage method (RMSE: 8.69 m, bias: 4.81 m) and the previous four-stage method (RMSE: 7.72 m, bias: −2.87 m).