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Appl. Sci., Volume 11, Issue 14 (July-2 2021) – 427 articles

Cover Story (view full-size image): We have studied the inhibiting effect of ebselen, the most famous organoselenium compound with pharmacological activity, on the SARS-CoV-2 virus. Its antiviral potential is related to its capacity to covalently bind to the main SARS-CoV-2 protease. Particularly, we provide an explanation on the details of this chemical mechanism and the relevance of the N-Se bond, as well as provide thermodynamic support to a very recent mechanistic hypothesis. We highlight how the main metabolites of ebselen are less active than the parent compound, an aspect often not captured in in vitro studies. View this paper
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Article
Performance Evaluation of Low-Cost Multi-Frequency GNSS Receivers and Antennas for Displacement Detection
Appl. Sci. 2021, 11(14), 6666; https://doi.org/10.3390/app11146666 - 20 Jul 2021
Cited by 2 | Viewed by 1080
Abstract
Low-cost Global Navigation Satellite System (GNSS) receivers are currently used in various engineering applications. These low-cost devices are regarded as suitable sensors for applications in areas with a high risk of instrument damage. The main objectives of this research were to identify the [...] Read more.
Low-cost Global Navigation Satellite System (GNSS) receivers are currently used in various engineering applications. These low-cost devices are regarded as suitable sensors for applications in areas with a high risk of instrument damage. The main objectives of this research were to identify the size of displacements that can be detected in relative and absolute positioning modes by low-cost GNSS instruments and to compare the results of selected antennas. Additionally, geodetic and low-cost GNSS instruments were compared in the level of observations. For this study, low-cost SimpleRTK2B V1 boards, which house ZED-F9P GNSS chips, and three low-cost antennas, namely, Survey, Tallysman TW3882, and Survey Calibrated, were selected. While antenna calibration parameters are known for the last antenna, this is not the case for the first two. For testing purposes, a geodetic network consisting of four points was established; horizontal and vertical movements were imposed by a special mechanism with high accuracy. In relative positioning mode, the results indicate that the Survey Calibrated antenna can detect horizontal and vertical displacements with sizes of 4 mm, and 6 mm, respectively. In the detection of horizontal displacements, the performance of the Survey antenna was not as good as that of Tallysman, and the sizes of detected displacements were 6 mm and 4 mm for the first, and second antennas, respectively. Vertical displacements of 9 mm were detected using both Survey and Tallysman antennas. In absolute positioning mode, Survey Calibrated also had better performance than the Tallysman antenna, and spatial displacements of 20 mm or greater were detected by low-cost GNSS instruments. The observations made with low-cost and geodetic GNSS instruments were compared, and the latter showed better performance. However, the differences in cycle slips and the noise of phase observations were inferior. Considering their cost and proven performance, it can be concluded that such sensors can be considered for setting up a highly accurate but low-cost geodetic monitoring system. Full article
(This article belongs to the Special Issue GNSS Techniques for Land and Structure Monitoring)
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Article
Study on Prevention and Treatment Strategy of Asphalt Ultraviolet (UV) Aging Based on UV Climate Zoning in China
Appl. Sci. 2021, 11(14), 6665; https://doi.org/10.3390/app11146665 - 20 Jul 2021
Viewed by 779
Abstract
The purpose of this paper, based on the amount of ultraviolet (UV) radiation in different areas of China, was to give the corresponding measures to prevent UV aging of asphalt. In this paper, based on the average annual amount of UV radiation in [...] Read more.
The purpose of this paper, based on the amount of ultraviolet (UV) radiation in different areas of China, was to give the corresponding measures to prevent UV aging of asphalt. In this paper, based on the average annual amount of UV radiation in China in the past 30 years and the characteristics of UV aging of asphalt, the climatic zoning of UV radiation of asphalt in China was proposed. A variety of base asphalts and styrene–butadiene–styrene block copolymer (SBS) modified asphalts were selected to carry out a UV radiation test, and the relationship between UV radiation amount and viscosity, low-temperature performance, and the rheological properties of asphalt were studied. The equivalent aging indexes of asphalt during UV radiation were selected, the UV aging equation of asphalt was proposed, and the equivalent UV aging relationship among different UV climate zones was established. The prevention and control strategies of UV aging of asphalt among different zones were proposed, and the above theory was verified using a trial road. The main conclusions in the paper are presented: The climate zoning of asphalt UV radiation in China can be divided into three zones: zone I with an annual UV radiation less than or equal to 69.4 kW·h/m2 in the last 30 years; zone II with an annual UV radiation of 69.4~81.4 kW·h/m2 in the last 30 years; zone III with an annual UV radiation more than or equal to 81.4 kW·h/m2 in the last 30 years. The greater the amount of UV radiation, the greater the loss rate of penetration and ductility. For the same kind of asphalt, there is a relatively stable functional relationship between the loss rate and the amount of UV radiation. The results also show that UV radiation changes the proportion of viscous and elastic components in asphalt, showing that the proportion of viscous components decreases and the proportion of elastic components increases. The penetration loss rate and ductility loss rate of asphalt can be used as equivalent UV aging indexes of asphalt. Under the same outdoor UV irradiation time, for asphalt to achieve the same technical performance as zone I, the anti-UV ability of zone II needs to be improved by more than 5%, and that of zone III needs to be improved by more than 10%. Engineering practice has proved that the zoning established in this paper and the corresponding UV control measures are basically reasonable. Full article
(This article belongs to the Section Civil Engineering)
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Article
Technical-Economic Evaluation of the Effectiveness of Measures Applied to the Artificial Lighting System of a School
Appl. Sci. 2021, 11(14), 6664; https://doi.org/10.3390/app11146664 - 20 Jul 2021
Cited by 1 | Viewed by 771
Abstract
Ensuring optimum interior lighting is a topic of great importance, as this influences not only the well-being of users but also the optimal performance of visual tasks. Lighting can be natural, but if not sufficient, it can be compensated with artificial lighting. This [...] Read more.
Ensuring optimum interior lighting is a topic of great importance, as this influences not only the well-being of users but also the optimal performance of visual tasks. Lighting can be natural, but if not sufficient, it can be compensated with artificial lighting. This study highlights a methodology for designing a new lighting system that takes into account both technical and economic aspects. The method was applied to an existing school located in southern Italy, in which the electricity consumption is related to the current lighting system. The school is chosen as being representative of the construction type and layout of many local schools. In addition, the coexistence of several visual tasks with different design requisites (e.g., illuminance levels) makes the school a very complex environment. The school lighting is modelled in Google SketchUp and imported into Daysim to simulate the yearly and hourly daylight indoor contribution. Dialux Evo has been used to simulate and design artificial lighting. The results show a reduction of energy consumption of 33% with the simple replacement of fluorescent luminaires with LEDs, while the LED lamp dimming and modulation for rows of luminaires leads to a 95% reduction in energy consumption compared with the current state. Full article
(This article belongs to the Special Issue Recent Advances in Lighting for Energy Efficiency and Sustainability)
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Article
A Paired Learner-Based Approach for Concept Drift Detection and Adaptation in Software Defect Prediction
Appl. Sci. 2021, 11(14), 6663; https://doi.org/10.3390/app11146663 - 20 Jul 2021
Viewed by 1160
Abstract
The early and accurate prediction of defects helps in testing software and therefore leads to an overall higher-quality product. Due to drift in software defect data, prediction model performances may degrade over time. Very few earlier works have investigated the significance of concept [...] Read more.
The early and accurate prediction of defects helps in testing software and therefore leads to an overall higher-quality product. Due to drift in software defect data, prediction model performances may degrade over time. Very few earlier works have investigated the significance of concept drift (CD) in software-defect prediction (SDP). Their results have shown that CD is present in software defect data and tha it has a significant impact on the performance of defect prediction. Motivated from this observation, this paper presents a paired learner-based drift detection and adaptation approach in SDP that dynamically adapts the varying concepts by updating one of the learners in pair. For a given defect dataset, a subset of data modules is analyzed at a time by both learners based on their learning experience from the past. A difference in accuracies of the two is used to detect drift in the data. We perform an evaluation of the presented study using defect datasets collected from the SEACraft and PROMISE data repositories. The experimentation results show that the presented approach successfully detects the concept drift points and performs better compared to existing methods, as is evident from the comparative analysis performed using various performance parameters such as number of drift points, ROC-AUC score, accuracy, and statistical analysis using Wilcoxon signed rank test. Full article
(This article belongs to the Special Issue Artificial Intelligence and Machine Learning in Software Engineering)
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Article
Performing Cache Timing Attacks from the Reconfigurable Part of a Heterogeneous SoC—An Experimental Study
Appl. Sci. 2021, 11(14), 6662; https://doi.org/10.3390/app11146662 - 20 Jul 2021
Viewed by 602
Abstract
Cache attacks are widespread on microprocessors and multi-processor system-on-chips but have not yet spread to heterogeneous systems-on-chip such as SoC-FPGA that are found in increasing numbers of applications on servers or in the cloud. This type of SoC has two parts: a processing [...] Read more.
Cache attacks are widespread on microprocessors and multi-processor system-on-chips but have not yet spread to heterogeneous systems-on-chip such as SoC-FPGA that are found in increasing numbers of applications on servers or in the cloud. This type of SoC has two parts: a processing system that includes hard components and ARM processor cores and a programmable logic part that includes logic gates to be used to implement custom designs. The two parts communicate via memory-mapped interfaces. One of these interfaces is the accelerator coherency port that provides optional cache coherency between the two parts. In this paper, we discuss the practicability and potential threat of inside-SoC cache attacks using the cache coherency mechanism of a complex heterogeneous SoC-FPGA. We provide proof of two cache timing attacks Flush+Reload and Evict+Time when SoC-FPGA is targeted, and proof of hidden communication using a cache-based covert channel. The heterogeneous SoC-FPGA Xilinx Zynq-7010 is used as an experimental target. Full article
(This article belongs to the Special Issue Side Channel Attacks in Embedded Systems)
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Article
Modified Contrast-Detail Phantom for Determination of the CT Scanners Abilities for Low-Contrast Detection
Appl. Sci. 2021, 11(14), 6661; https://doi.org/10.3390/app11146661 - 20 Jul 2021
Cited by 2 | Viewed by 713
Abstract
Computerised tomography (CT) continues to be a corner stone medical and radiologic imaging modalities in radiology and radiotherapy departments. Its importance lies in its efficiency in low contrast detectability (LCD). The assessment of such capabilities requires rigorous image quality analysis using special designed [...] Read more.
Computerised tomography (CT) continues to be a corner stone medical and radiologic imaging modalities in radiology and radiotherapy departments. Its importance lies in its efficiency in low contrast detectability (LCD). The assessment of such capabilities requires rigorous image quality analysis using special designed phantoms with different densities as well as variation in atomic mass numbers (A) of the material. Absence of such ranges of densities and atomic mass numbers, limits the dynamic range of assessment. An example is Catphan phantom which represents only three subject contrast levels 0.3, 0.5 and 1 per cent. This project aims to present a phantom with extended range of available subject contrast to include very low-level values and to increase its dynamic scale. With this design, a relatively large number of different contrast objects (holes) can be presented for imaging by a CT scanner to assess its LCD ability. We shall thus introduce another LCD phantom to complement the existing ones, such as Catphan. The cylindrical phantom is constructed using Poly (methyl methacrylate) (PMMA), with craters (holes) having dimensions that gradually increase from 1.0 to 12.5 mm penetrated in configuration that extend from the centre to the corner. Each line of the drilled holes in the phantom is filled with contrast material of specific concentrations. As opposed to the phantom of low detail contrast used in planar imaging, the iodine (contrast material) in this phantom replaces the depth of the phantom holes. The iodine could be reduced to 0.2 l milli-Molar (mM) and can be varied for the next line of holes by a small increment depending on the required level of contrast detectability assessment required. Full article
(This article belongs to the Special Issue Nuclear and Radiation Physics in Medicine)
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Communication
Anti-Inflammatory Effect of Cudrania tricuspidata Extract and Stewartia koreana Extract Mixture in a Collagen-Induced Arthritis Mouse Model
Appl. Sci. 2021, 11(14), 6660; https://doi.org/10.3390/app11146660 - 20 Jul 2021
Viewed by 818
Abstract
Cudrania tricuspidata extracts (CTE) and Stewartia koreana extracts (SKE) are viable drugs for managing inflammation. We investigated the nitric oxide levels of CTE and a mixture of CTE/SKE (CTE mix) against lipopolysaccharide-induced RAW264.7 cells. In addition, we administered the CTE and CTE mix [...] Read more.
Cudrania tricuspidata extracts (CTE) and Stewartia koreana extracts (SKE) are viable drugs for managing inflammation. We investigated the nitric oxide levels of CTE and a mixture of CTE/SKE (CTE mix) against lipopolysaccharide-induced RAW264.7 cells. In addition, we administered the CTE and CTE mix to mice with collagen-induced arthritis to confirm an anti-inflammatory effect against rheumatoid arthritis. We analyzed arthritis symptoms by oral administration of CTE mix using a CIA-induced animal model and analyzed the inhibitory activity of NO production with in vitro experiments. Both the CTE and CTE mix decreased nitric oxide levels, and a 2:1 ratio of CTE mix was most effective in vivo among the varying ratios of CTE mix tested. The spleen size increased by about 2.1 times, and the lymph node size decreased by about 2.5 times relative compared to the vehicle group. In blood biochemical analyses, tumor necrosis factor–α levels decreased by about three times, interleukin-1β and interleukin-6 levels were reduced by about eight times and three times, and PRG4 expression levels were increased by about 2.5 times relative to the vehicle group. We suggest that the CTE mix was superior to CTE alone and has potential as an anti-inflammatory treatment for patients with rheumatoid arthritis. Full article
(This article belongs to the Special Issue Herbal Medicines and Their Beneficial Effect in Inflammatory Diseases)
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Review
Removal of Pharmaceuticals from Water by Adsorption and Advanced Oxidation Processes: State of the Art and Trends
Appl. Sci. 2021, 11(14), 6659; https://doi.org/10.3390/app11146659 - 20 Jul 2021
Cited by 11 | Viewed by 1748
Abstract
Pharmaceutical products have become a necessary part of life. Several studies have demonstrated that indirect exposure of humans to pharmaceuticals through the water could cause negative effects. Raw sewage and wastewater effluents are the major sources of pharmaceuticals found in surface waters and [...] Read more.
Pharmaceutical products have become a necessary part of life. Several studies have demonstrated that indirect exposure of humans to pharmaceuticals through the water could cause negative effects. Raw sewage and wastewater effluents are the major sources of pharmaceuticals found in surface waters and drinking water. Therefore, it is important to consider and characterize the efficiency of pharmaceutical removal during wastewater and drinking-water treatment processes. Various treatment options have been investigated for the removal/reduction of drugs (e.g., antibiotics, NSAIDs, analgesics) using conventional or biological treatments, such as activated sludge processes or bio-filtration, respectively. The efficiency of these processes ranges from 20–90%. Comparatively, advanced wastewater treatment processes, such as reverse osmosis, ozonation and advanced oxidation technologies, can achieve higher removal rates for drugs. Pharmaceuticals and their metabolites undergo natural attenuation by adsorption and solar oxidation. Therefore, pharmaceuticals in water sources even at trace concentrations would have undergone removal through biological processes and, if applicable, combined adsorption and photocatalytic degradation wastewater treatment processes. This review provides an overview of the conventional and advanced technologies for the removal of pharmaceutical compounds from water sources. It also sheds light on the key points behind adsorption and photocatalysis. Full article
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Article
Beetroot Microencapsulation with Pea Protein Using Spray Drying: Physicochemical, Structural and Functional Properties
Appl. Sci. 2021, 11(14), 6658; https://doi.org/10.3390/app11146658 - 20 Jul 2021
Cited by 4 | Viewed by 879
Abstract
Beetroot is a root vegetable with carotenoids, phenols, vitamins, minerals, and water-soluble betalain pigments such as betacyanins (red-violet color) and betaxanthins (yellow-orange color), which have many nutritional and health benefits. Its use in the food industry is mainly as a powdered natural dye. [...] Read more.
Beetroot is a root vegetable with carotenoids, phenols, vitamins, minerals, and water-soluble betalain pigments such as betacyanins (red-violet color) and betaxanthins (yellow-orange color), which have many nutritional and health benefits. Its use in the food industry is mainly as a powdered natural dye. This study aims to investigate the effect of adding pea protein to beetroot juice as an encapsulating agent, and the spray-dried temperature on the physicochemical, structural, and functional properties of the powder. The spray drying was conducted at 125 and 150 °C with 3.5% and 7% pea protein used in the mixtures with the beetroot juice. The water content, bulk density, porosity, hygroscopicity, water solubility, water absorption index, color, and microstructure of the obtained powder were determined. In addition, betacyanin, total phenols, antioxidant capacity, and powder encapsulate efficiency were analyzed. Using pea protein in the spray drying of beetroot juice had shown high yields of spray drying and good characteristics of the powdered product. Beetroot powder with 7% of pea protein was more porous and luminous, and less hygroscopic than beetroot powder with 3.5% of pea protein. However, the use of 7% of pea protein increased the amount of water immobilized by the samples and reduced the soluble solids present in the product compared to beetroot powder with 3.5% of pea protein. The use of 7% of pea protein protected beetroot bioactive compound higher than the use of 3.5%. Higher spray-drying temperature (150 °C) significantly decreased phenols content and antioxidant capacity of the beetroot powders (p < 0.05). Results showed using 7% pea protein mixed with beetroot juice and a 125 °C spray-drying temperature gave the most content of the studied bioactive compounds and antioxidant capacity. Moreover, the proposal gives more stable powders from a functionality viewpoint because it showed the higher encapsulate efficiency. Full article
(This article belongs to the Special Issue Advanced Microencapsulation in Food Science)
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Article
Segmenting 20 Types of Pollen Grains for the Cretan Pollen Dataset v1 (CPD-1)
Appl. Sci. 2021, 11(14), 6657; https://doi.org/10.3390/app11146657 - 20 Jul 2021
Cited by 2 | Viewed by 946
Abstract
Pollen analysis and the classification of several pollen species is an important task in melissopalynology. The development of machine learning or deep learning based classification models depends on available datasets of pollen grains from various plant species from around the globe. In this [...] Read more.
Pollen analysis and the classification of several pollen species is an important task in melissopalynology. The development of machine learning or deep learning based classification models depends on available datasets of pollen grains from various plant species from around the globe. In this paper, Cretan Pollen Dataset v1 (CPD-1) is presented, which is a novel dataset of grains from 20 pollen species from plants gathered in Crete, Greece. The pollen grains were prepared and stained with fuchsin, in order to be captured by a camera attached to a microscope under a ×400 magnification. In addition, a pollen grain segmentation method is presented, which segments and crops each unique pollen grain and achieved an overall detection accuracy of 92%. The final dataset comprises 4034 segmented pollen grains of 20 different pollen species, as well as the raw data and ground truth, as annotated by an expert. The developed dataset is publicly accessible, which we hope will accelerate research in melissopalynology. Full article
(This article belongs to the Special Issue Machine Learning in Agricultural Informatization)
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Article
Enabling Role-Based Orchestration for Cloud Applications
Appl. Sci. 2021, 11(14), 6656; https://doi.org/10.3390/app11146656 - 20 Jul 2021
Viewed by 661
Abstract
With the rapidly growing popularity of cloud services, the cloud computing faces critical challenges to orchestrate the deployment and operation of cloud applications on heterogenous cloud platforms. Cloud applications are built on a platform model that abstracts away underlying platform-specific details, so that [...] Read more.
With the rapidly growing popularity of cloud services, the cloud computing faces critical challenges to orchestrate the deployment and operation of cloud applications on heterogenous cloud platforms. Cloud applications are built on a platform model that abstracts away underlying platform-specific details, so that their orchestration can benefit from the abstract view and flexibility of the underlying platform configuration. However, considerable efforts are still required to properly manage complicated cloud applications. This paper proposes a model-driven approach to cloud application orchestration which promotes the concerns of distinct roles for cloud system provisioning and operation. By establishing a set of capabilities as modeling constructs, our approach allows TOSCA-based application topology itself and its orchestration needs to be specified in a way to provide a more targeted support for different needs and concerns of application developers and operators. With novel orchestration features like application topology description, platform capability modeling, and role-awareness for cloud application orchestration, it can significantly reduce the complexity of application orchestration in diverse cloud environments. To show the feasibility and effectiveness of our proposal for cloud application orchestration, we present a proof-of-concept orchestration system implementation and evaluate its deployment and orchestration results in a Kubernetes cluster. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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Article
EDEM Investigation and Experimental Evaluation of Abrasive Wear Resistance Performance of Bionic Micro-Thorn and Convex Hull Geometrically Coupled Structured Surface
Appl. Sci. 2021, 11(14), 6655; https://doi.org/10.3390/app11146655 - 20 Jul 2021
Cited by 1 | Viewed by 751
Abstract
Procambarus clarkii was found to have excellent anti-wear performance against abrasive materials. To improve the wear resistance performance of the soil-engaging component of agricultural machinery, in this study, the micro-thorn and convex hull coupled geometrical structured surfaces inspired from the cephalothorax exoskeleton of [...] Read more.
Procambarus clarkii was found to have excellent anti-wear performance against abrasive materials. To improve the wear resistance performance of the soil-engaging component of agricultural machinery, in this study, the micro-thorn and convex hull coupled geometrical structured surfaces inspired from the cephalothorax exoskeleton of the Procambarus clarkii was selected as the bionic prototype. By adopting bionic engineering techniques, three types of novel geometrical structured surfaces were proposed, which were bionic single, double and triple micro-thorn coupled convex hull surfaces (Bionic Type 2, 3 and 4, respectively). The anti-abrasive wear properties of these proposed geometrical surfaces were compared with a conventional bionic convex hull structured surface (Bionic Type 1) and a surface without any structures (smooth). Abrasive wear tests were conducted by using a rotational abrasive wear testing system. The accumulative test time was 80 h and the total wear distance was 6.09 × 105 m. By adopting the EDEM software (discrete element modeling), the Archard Wear model was selected to simulate the wear behavior of five different surfaces. In addition, the wear mechanisms of different surfaces were investigated. The results showed that the smooth surface suffered the most severe abrasive were, the abrasion loss reached 194.1 mg. The anti-abrasive properties of bionic geometric structured non-smooth surfaces were greatly improved; the reduction in terms of abrasion losses ranged between 20.4% and 94.1%, as compared with the smooth surface. The wear resistance property of micro-thorn and convex hull coupled structured surfaces were greatly improved as compared with convex hull and smooth surface. Bionic Type 3 was found to have the best anti-abrasive wear property: the abrasion loss was 11.5 mg. The wear morphology was observed by a scanning electron microscope. Smooth surface was characterized with wide, large size of grinding debris, while the bionic non-smooth surface featured narrow and small size abrasive dust. The results obtained from EDEM simulation agreed well with those of the aforementioned real scenario tests. It was revealed that the wear areas of the micro-thorn and convex hull coupled structured surface were mainly concentrated on the edge of convex hull and micro-thorn that faced the coming direction of particle flow. The geometric structure of the convex hull had beneficial effects on changing the movement behavior of particles, which means the stream of particle flow could be altered from a sliding to rolling state. Consequently, the ploughing and cutting phenomena of particles that act on the surfaces were greatly mitigated. Moreover, after being coupled with micro-thorns, the anti-abrasive wear preparty of the bionic convex hull geometrical structured surface was further improved. The rebound angle of particle flow that contacted the bionic micro-thorn coupled convex hull structured surface was greater than that of the conventional convex hull surface. Therefore, the dispersion effect of particle flow was further enhanced, since the movement behavior of the subsequent impact particle flow was altered. As a result, the wear of the bionic non-smooth surface was further reduced. This biconically inspired novel micro-thorn and convex hull coupled structured surface could provide theatrical and technical references to enhance the wear resistance performance of the soil-engaging component of agricultural machinery and mitigate the problem of abrasive wear failure. Full article
(This article belongs to the Special Issue Advances in Surface Modification of the Materials)
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Article
Identification of a Human-Structure Interaction Model on an Ultra-Lightweight FRP Footbridge
Appl. Sci. 2021, 11(14), 6654; https://doi.org/10.3390/app11146654 - 20 Jul 2021
Cited by 7 | Viewed by 785
Abstract
Due to the high strength-to-weight ratio of fibre reinforced polymers (FRPs), human-induced vibration problematic remains as a subject to be fully comprehended in order to extend the use of composites in Bridge Engineering. Thus, this paper studies an ultra-lightweight FRP footbridge, which presents [...] Read more.
Due to the high strength-to-weight ratio of fibre reinforced polymers (FRPs), human-induced vibration problematic remains as a subject to be fully comprehended in order to extend the use of composites in Bridge Engineering. Thus, this paper studies an ultra-lightweight FRP footbridge, which presents excessive vertical vibrations when the fourth harmonic of a walking pedestrian is synchronised with the structure’s fundamental frequency. Focusing on the vertical bending mode, at 7.66 Hz, the bridge dynamic behaviour was assessed under the action of a single pedestrian crossing the facility at a step frequency of 1.9 Hz. As an over prediction of the footbridge response was computed using a moving force (MF) model available in a design guideline, a mass-spring-damper-actuator (MSDA) system was adopted to depict a walker. Hence, Human-Structure Interaction (HSI) phenomenon was considered. Employing the experimental results, parameters of the MSDA system were identified, leading to a HSI model that considers the first fourth harmonics of a walking human. Additionally, a parametric analysis was carried out, determining that the damping ratio of the human body and the load factor associated to the fourth harmonic are the most relevant parameters on the estimation of the response. The identified HSI model may be used as a first approximation to accurately predict the dynamic response of ultra-lightweight composite structures and should be extended to account for crowd-induced loads. Full article
(This article belongs to the Special Issue Bridge Dynamics: Volume II)
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Article
The Control of Renewable Energies to Improve the Performance of Multisource Heat Pump Systems: A Two-Case Study
Appl. Sci. 2021, 11(14), 6653; https://doi.org/10.3390/app11146653 - 20 Jul 2021
Cited by 1 | Viewed by 644
Abstract
In new and refurbished buildings, different energy sources are usually exploited to reach the Near Zero Energy Building target. Heat pumps and renewables are the most common adopted technologies. The coupling of the different components with a control logic conceived to exploit all [...] Read more.
In new and refurbished buildings, different energy sources are usually exploited to reach the Near Zero Energy Building target. Heat pumps and renewables are the most common adopted technologies. The coupling of the different components with a control logic conceived to exploit all energy contributions causes an implied design complexity. In this paper, two case studies were reported regarding the use of multisource heat pump systems: as main novelties, the correct design of the solar field (thermal or photovoltaic/thermal) in relation with the other sources (ground heat exchangers, ventilation heat recovery) for a given building and climate was reported in order to balance the energy drawn and injected into the ground around the year, and to attempt to reach the independency from the electric grid. Moreover, the relatively complex (compared to conventional heating or cooling) system controlling for multisource heat pump plants was simulated. The paper reported on the design of the plant, of the control logic, and the energy performance of two original multisource heat pump systems by means of dynamic simulation. In one case, real measured data were available as well. Very high primary energy ratios were obtained due to suitable control logics of the multisource plants, around 1.4 (based on measured data) and 4.7 (based on simulated data) for the first and second case, respectively. As a consequence, non-renewable primary energy consumptions of 37 and 3.9 kWh m−2 y−1 were determined, respectively. Full article
(This article belongs to the Special Issue New Challenges in the Control of Renewable Energy Sources)
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Article
Life Cycle Assessment of Different Waste Lubrication Oil Management Options in Serbia
Appl. Sci. 2021, 11(14), 6652; https://doi.org/10.3390/app11146652 - 20 Jul 2021
Cited by 3 | Viewed by 724
Abstract
On average, approximately 22 thousand tons of new lubrication oil were marketed annually in Serbia in the period 2015–2019. Less than 20% of the waste lubrication oil (WLO) generated was treated, whereas the remainder was mostly uncollected or improperly disposed of. The purpose [...] Read more.
On average, approximately 22 thousand tons of new lubrication oil were marketed annually in Serbia in the period 2015–2019. Less than 20% of the waste lubrication oil (WLO) generated was treated, whereas the remainder was mostly uncollected or improperly disposed of. The purpose of this study is to examine different WLO management scenarios that could be implemented in Serbia in the future and to quantify their potential environmental benefits. Different WLO treatment processes (namely the re-refining of used oil for base oil recovery, the use of WLO as a substitute to fossil fuels in cement kilns, and the combustion of WLO in waste incinerators with energy recovery) were evaluated using the life cycle assessment (LCA) and ReCiPe 2016 impact assessment methods. The LCA results obtained indicate that no single WLO treatment process consistently exerts diminished environmental impacts according to all the impact categories considered. From a human health perspective, the incineration of WLO in waste incinerators was found more favourable than the other treatment processes considered, whereas the combustion in cement kilns was the most favourable approach with regard to ecosystem protection. In terms of fossil fuel savings, re-refining technologies performed slightly better than the other processes considered. This can be accounted for by significant amounts of marketable co-products generated in the re-refining process, which can be used as a substitute to fossil-based primary products. Furthermore, a total of four possible WLO management scenarios were developed on the basis of the annual quantities of untreated WLO and a mix of treatment options. The results obtained indicate that up to 22,100 t CO2 equivalent and 34,300 t oil equivalent could be saved annually in Serbia provided the most favourable WLO management scenario is considered. Full article
(This article belongs to the Section Environmental Sciences)
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Article
Data-Driven Analyses of Low Salinity Waterflooding in Carbonates
Appl. Sci. 2021, 11(14), 6651; https://doi.org/10.3390/app11146651 - 20 Jul 2021
Cited by 2 | Viewed by 600
Abstract
Low salinity water (LSW) injection is a promising Enhanced Oil Recovery (EOR) technique that has the potential to improve oil recovery and has been studied by many researchers. LSW flooding in carbonates has been widely evaluated by coreflooding tests in prior studies. A [...] Read more.
Low salinity water (LSW) injection is a promising Enhanced Oil Recovery (EOR) technique that has the potential to improve oil recovery and has been studied by many researchers. LSW flooding in carbonates has been widely evaluated by coreflooding tests in prior studies. A closer look at the literature on LSW in carbonates indicates a number of gaps and shortcomings. It is difficult to understand the exact relationship between different controlling parameters and the LSW effect in carbonates. The active mechanisms involved in oil recovery improvement are still uncertain and more analyses are required. To predict LSW performance and study the mechanisms of oil displacement, data collected from available experimental studies on LSW injection in carbonates were analyzed using data analysis approaches. We used linear regression to study the linear relationships between single parameters and the incremental recovery factor (RF). Correlations between rock, oil, and brine properties and tertiary RF were weak and negligible. Subsequently, we analyzed the effect of oil/brine parameters on LSW performance using multivariable linear regression. Relatively strong linear correlations were found for a combination of oil/brine parameters and RF. We also studied the nonlinear relationships between parameters by applying machine learning (ML) nonlinear models, such as artificial neural network (ANN), support vector machine (SVM), and decision tree (DT). These models showed better data fitting results compared to linear regression. Among the applied ML models, DT provided the best correlation for oil/brine parameters, as ANN and SVM overfitted the testing data. Finally, different mechanisms involved in the LSW effect were analyzed based on the changes in the effluent PDIs concentration, interfacial tension, pH, zeta potential, and pressure drop. Full article
(This article belongs to the Section Materials Science and Engineering)
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Article
Human Umbilical Cord Mesenchymal Stem Cells in Combination with Hyaluronic Acid Ameliorate the Progression of Knee Osteoarthritis
Appl. Sci. 2021, 11(14), 6650; https://doi.org/10.3390/app11146650 - 20 Jul 2021
Cited by 1 | Viewed by 868
Abstract
The aim of this study is to evaluate the feasibility and usefulness of the human umbilical cord mesenchymal stem cells (hUC-MSCs) and hyaluronan acid (HA) combination to attenuate osteoarthritis progression in the knee while simultaneously providing some insights on the mitigation mechanism. In [...] Read more.
The aim of this study is to evaluate the feasibility and usefulness of the human umbilical cord mesenchymal stem cells (hUC-MSCs) and hyaluronan acid (HA) combination to attenuate osteoarthritis progression in the knee while simultaneously providing some insights on the mitigation mechanism. In vitro, the effect of hUC-MSCs with HA treatment on chondrocyte cell viability and the cytokine profile were analyzed. Additionally, the antioxidation capability of hUC-MSCs-CM (conditioned medium) with HA towards H2O2-induced chondrocyte cell damage was evaluated. The HA addition increased the hUC-MSC antioxidation capability and cytokine secretion, such as Dickkopf-related protein 1 (DKK-1) and hepatocyte growth factor (HGF), while no adverse effect on the cell viability was observed. In vivo, the intra-articular injection of hUC-MSCs with HA to a mono-iodoacetate (MIA)-induced knee osteoarthritis (KOA) rat model was performed and investigated. Attenuation of the KOA progression in the MIA-damaged rat model was seen best in hUC-MSCs with a HA combination compared to the vehicle control or each individual element. Combining hUC-MSCs and HA resulted in a synergistic effect, such as increasing the cell therapeutic capability while incurring no observable adverse effects. Therefore, this combinatorial therapy is feasible and has promising potential to ameliorate KOA progression. Full article
(This article belongs to the Special Issue Applied Sciences in Orthopaedics)
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Article
A Measurement-Based Message-Level Timing Prediction Approach for Data-Dependent SDFGs on Tile-Based Heterogeneous MPSoCs
Appl. Sci. 2021, 11(14), 6649; https://doi.org/10.3390/app11146649 - 20 Jul 2021
Viewed by 676
Abstract
Fast yet accurate performance and timing prediction of complex parallel data flow applications on multi-processor systems remains a very difficult discipline. The reason for it comes from the complexity of the data flow applications w.r.t. data dependent execution paths and the hardware platform [...] Read more.
Fast yet accurate performance and timing prediction of complex parallel data flow applications on multi-processor systems remains a very difficult discipline. The reason for it comes from the complexity of the data flow applications w.r.t. data dependent execution paths and the hardware platform with shared resources, like buses and memories. This combination may lead to complex timing interferences that are difficult to express in pure analytical or classical simulation-based approaches. In this work, we propose the combination of timing measurement and statistical simulation models for probabilistic timing and performance prediction of Synchronous Data Flow (SDF) applications on MPSoCs with shared memories. We exploit the separation of computation and communication in our SDF model of computation to set-up simulation-based performance prediction models following different abstraction approaches. We especially propose a message-level communication model driven by a data-dependent probabilistic execution phase timing model. We compare our work against measurement on two case-studies from the computer vision domain: a Sobel filter and a JPEG decoder. We show that the accuracy and execution time of our modeling and evaluation framework outperforms existing approaches and is suitable for a fast yet accurate design space exploration. Full article
(This article belongs to the Special Issue New Trends in Real-Time Embedded Systems)
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Article
Gaze Behavior and Positioning of Referee Teams during Three-Point Shots in Basketball
Appl. Sci. 2021, 11(14), 6648; https://doi.org/10.3390/app11146648 - 20 Jul 2021
Cited by 2 | Viewed by 945
Abstract
This study looks at the visual scan patterns of high-class basketball referees. Using mobile eye-tracking devices, referees’ gaze behavior was analyzed during the execution of three-point shots in the official pre-season games of Germany’s men’s professional basketball league. We evaluated the extent to [...] Read more.
This study looks at the visual scan patterns of high-class basketball referees. Using mobile eye-tracking devices, referees’ gaze behavior was analyzed during the execution of three-point shots in the official pre-season games of Germany’s men’s professional basketball league. We evaluated the extent to which the referees fulfill the tasks assigned to them, where do they look, and to what extent does their gaze behavior overlap during a three-point shot. Results indicate that referees who are far away from the ball and are, therefore, not responsible for observing the actual shot, tend to comply with their areas of responsibility less often than referees standing nearer to the ball, i.e., they appear to observe the ball more than required (ball watching) at the expense of other areas that they are required to be observing at the beginning of the shooting process. However, referees spend a very small part of a three-point shot looking at the same areas of interest. This indicates that referee teams’ allocation of gaze is rather effective, remaining in line with FIBA recommendations and is presumably not the main cause for errors in officiating. Full article
(This article belongs to the Special Issue Diagnostic and Interventions in Team Sports)
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Article
A Co-Rotational Meshfree Method for the Geometrically Nonlinear Analysis of Structures
Appl. Sci. 2021, 11(14), 6647; https://doi.org/10.3390/app11146647 - 20 Jul 2021
Viewed by 561
Abstract
This paper presents a co-rotational beam formulation, which is used for geometric nonlinear analysis with the differential reproducing kernel (DRK) approximation collocation method. The present formulation, based on the Timoshenko beam hypothesis, is capable of effectively solving geometrically nonlinear problems such as large [...] Read more.
This paper presents a co-rotational beam formulation, which is used for geometric nonlinear analysis with the differential reproducing kernel (DRK) approximation collocation method. The present formulation, based on the Timoshenko beam hypothesis, is capable of effectively solving geometrically nonlinear problems such as large deformation, postbuckling, lateral buckling, and snap-through problems. The kinematics have been constructed with the concept of co-rotational formulation adopted in the finite element method (FEM). A meshfree method based on the differential reproducing kernel (DRK) approximation collocation method, combined with the Newton–Raphson method, is employed to solve the strong forms of the geometrically nonlinear problems. The DRK method takes full advantage of the meshfree method. Moreover, only a scattered set of nodal points is necessary for the discretization. No elements or mesh connectivity data are required. Therefore, DRK will be able to completely circumvent the problems of mesh dependence and mesh distortion. The effectiveness of this study and its performance are shown through several numerical applications. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2020)
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Article
Head-Related Transfer Functions for Dynamic Listeners in Virtual Reality
Appl. Sci. 2021, 11(14), 6646; https://doi.org/10.3390/app11146646 - 20 Jul 2021
Cited by 1 | Viewed by 1471
Abstract
In dynamic virtual reality, visual cues and motor actions aid auditory perception. With multimodal integration and auditory adaptation effects, generic head-related transfer functions (HRTFs) may yield no significant disadvantage to individual HRTFs regarding accurate auditory perception. This study compares two individual HRTF sets [...] Read more.
In dynamic virtual reality, visual cues and motor actions aid auditory perception. With multimodal integration and auditory adaptation effects, generic head-related transfer functions (HRTFs) may yield no significant disadvantage to individual HRTFs regarding accurate auditory perception. This study compares two individual HRTF sets against a generic HRTF set by way of objective analysis and two subjective experiments. First, auditory-model-based predictions examine the objective deviations in localization cues between the sets. Next, the HRTFs are compared in a static subjective (N=8) localization experiment. Finally, the localization accuracy, timbre, and overall quality of the HRTF sets are evaluated subjectively (N=12) in a six-degrees-of-freedom audio-visual virtual environment. The results show statistically significant objective deviations between the sets, but no perceived localization or overall quality differences in the dynamic virtual reality. Full article
(This article belongs to the Special Issue Psychoacoustics for Extended Reality (XR))
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Article
Regression Approach to a Novel Lateral Flatness Leveling System for Smart Manufacturing
Appl. Sci. 2021, 11(14), 6645; https://doi.org/10.3390/app11146645 - 20 Jul 2021
Viewed by 754
Abstract
Sheet metal coils are widely used in the steel, automotive, and electronics industries. Many of these coils are processed through metal stamping or laser cutting to form different types of shapes. Sheet metal coil leveling is an essential procedure before any metal forming [...] Read more.
Sheet metal coils are widely used in the steel, automotive, and electronics industries. Many of these coils are processed through metal stamping or laser cutting to form different types of shapes. Sheet metal coil leveling is an essential procedure before any metal forming process. In practice, this leveling procedure is now executed by operators and primarily relies on their experience, resulting in many trials and errors before settling on the correct machine parameters. In smart manufacturing, it is required to digitize the machine’s parameters to achieve such a leveling process. Although smart manufacturing has been adopted in the manufacturing industry in recent years, it has not been implemented in steel leveling. In this paper, a novel leveling method for flatness leveling is proposed and validated with data collected by flatness sensors for measuring each roll adjustment position, which is later processed through the multi-regression method. The regression results and experienced machine operator results are compared. From this research, not only can the experience of the machine operators be digitized, but the results also indicate the feasibility of the proposed method to offer more efficient and accurate machine settings for metal leveling operations. Full article
(This article belongs to the Special Issue Metal Forming)
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Article
Detection and Model of Thermal Traces Left after Aggressive Behavior of Laboratory Rodents
Appl. Sci. 2021, 11(14), 6644; https://doi.org/10.3390/app11146644 - 20 Jul 2021
Viewed by 553
Abstract
Automation of complex social behavior analysis of experimental animals would allow for faster, more accurate and reliable research results in many biological, pharmacological, and medical fields. However, there are behaviors that are not only difficult to detect for the computer, but also for [...] Read more.
Automation of complex social behavior analysis of experimental animals would allow for faster, more accurate and reliable research results in many biological, pharmacological, and medical fields. However, there are behaviors that are not only difficult to detect for the computer, but also for the human observer. Here, we present an analysis of the method for identifying aggressive behavior in thermal images by detecting traces of saliva left on the animals’ fur after a bite, nape attack, or grooming. We have checked the detection capabilities using simulations of social test conditions inspired by real observations and measurements. Detection of simulated traces different in size and temperature on single original frame revealed the dependence of the parameters of commonly used corner detectors (R score, ranking) on the parameters of the traces. We have also simulated temperature of saliva changes in time and proved that the detection time does not affect the correctness of the approximation of the observed process. Furthermore, tracking the dynamics of temperature changes of these traces allows to conclude about the exact moment of the aggressive action. In conclusion, the proposed algorithm together with thermal imaging provides additional data necessary to automate the analysis of social behavior in rodents. Full article
(This article belongs to the Special Issue Recent Advances in Biomedical Image Processing)
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Article
Investigations of the Surface of Heritage Objects and Green Bioremediation: Case Study of Artefacts from Maramureş, Romania
Appl. Sci. 2021, 11(14), 6643; https://doi.org/10.3390/app11146643 - 20 Jul 2021
Cited by 10 | Viewed by 1004
Abstract
Old textiles are important elements of thecultural heritage. As a result of their composition mostly of natural elements old textiles are extremely prone to physical and chemical degradation due to fungal action. The treatments usually applied for the cleaning of heritage textiles target [...] Read more.
Old textiles are important elements of thecultural heritage. As a result of their composition mostly of natural elements old textiles are extremely prone to physical and chemical degradation due to fungal action. The treatments usually applied for the cleaning of heritage textiles target the use of synthetic fungicides, which are potentially harmful to both human health and the environment. Numerous studies highlight as an alternative to the use of conventional antifungals, the employment of essential oils and plant extracts, which are environmentally friendly and which have no adverse effects on human health. Against this background the present study aims to test six essential oils (Lavandula angustifolia, Citrus limon, Mentha piperita, Marjoram, Melaleuca alternifolia, Origanum vulgare) to establish their inhibitory effects against fungi identified on an old piece of traditional Romanian clothing from Maramureş. For the study, the types of fungi present on the objects was determined primarily through the open plates technique and microscopic identification. After identification, the essential oils were applied to the delimited surfaces, and their effects observed up to 32 days after application. The results show that these essential oils have a strong inhibitory effect on such fungal genera as Penicillinum sp., Cladosporium sp., Aspergillus spp., Candida guillermondii, Botrys sp., Mucor sp., having no observable side-effects on the physical properties of the materials concerned. The antimicrobial effects that essential oils and plant extracts have in the short term must be tested in future to ensure the enhanced preservation of heritage textiles and the health integrity of the restorers and visitors who view them in museums, collections or exhibitions. Full article
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Article
In Vitro Evaluation of the Antibacterial and Antioxidant Activities of Extracts of Gracilaria gracilis with a View into Its Potential Use as an Additive in Fish Feed
Appl. Sci. 2021, 11(14), 6642; https://doi.org/10.3390/app11146642 - 20 Jul 2021
Cited by 1 | Viewed by 892
Abstract
Fish in aquaculture systems are subject to several stressors that inhibit the immune response and potentiate the development of disease and increased mortality. The inclusion of additives in the fish diet, namely seaweeds or their extracts, that are natural sources of bioactive compounds [...] Read more.
Fish in aquaculture systems are subject to several stressors that inhibit the immune response and potentiate the development of disease and increased mortality. The inclusion of additives in the fish diet, namely seaweeds or their extracts, that are natural sources of bioactive compounds can be an important tool for promoting the health and well-being of these animals. The present study aims at the development of sustainable and effective methodologies for the extraction of bioactive compounds of the red seaweed Gracilaria gracilis, exploring its antibacterial and antioxidant potential and considering its potential use as an additive for functional fish feeds. The yield of the extraction methods was evaluated upon the use of sequential solid–liquid extraction techniques with ethanol and water as solvents, different extraction temperatures (room temperature: 40 °C and 70 °C), and extraction time. The results demonstrated that the adoption extraction times of 30 min at 40 °C provided higher yields. We also evaluated the antioxidant capacity and the antibacterial properties of the obtained extracts against different strains that cause fish diseases by disk diffusion and broth microdilution methods. The antioxidant activity was determined by the DPPH reducing capacity method and quantification of total polyphenols content (TPC). With these results, we can establish extraction procedures that allow the future use of G. gracilis extracts, with antibacterial and antioxidant effects in a safe and effective way. Full article
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Article
Simple HPLC-PDA Analysis to Determine Illegal Synthetic Dyes in Herbal Medicines
Appl. Sci. 2021, 11(14), 6641; https://doi.org/10.3390/app11146641 - 20 Jul 2021
Viewed by 747
Abstract
Various synthetic dyes are artificially added to herbal medicines for the purpose of visual attraction. In order to monitor the illegal usage of synthetic dyes in herbal medication, a rapid and straightforward analysis method to determine synthetic dyes is required. The study aimed [...] Read more.
Various synthetic dyes are artificially added to herbal medicines for the purpose of visual attraction. In order to monitor the illegal usage of synthetic dyes in herbal medication, a rapid and straightforward analysis method to determine synthetic dyes is required. The study aimed to develop and validate a high-performance liquid chromatography (HPLC) analysis to determine ten synthetic dyes in Hawthorn fruit, Cornus fruit, and Schisandra fruit. Ten synthetic dyes such as Tartrazine, Sunset yellow, Metanil yellow, Auramine O, Amaranth, Orange II, Acid red 73, Amaranth, New Coccine, Azorubine, and Erythrosine B, were extracted using 50 mM ammonium acetate in 70% MeOH; then separated by gradient elution with a mobile phase consisting of acetonitrile and 50 mM ammonium acetate in distilled water using a photodiode array detector (PDA) at 428 nm or 500 nm. In addition, this study established the LC-MS/MS method to confirm the existence of synthetic dyes in the positive sample solution. The HPLC analysis had good linearity (r2 > 0.999). The recoveries of this method ranged from 74.6~132.1%, and the relative standard deviation (RSD) values were less than 6.9%. Most of the samples fulfilled the acceptance criteria of the AOAC guideline. This study demonstrates that the HPLC analysis can be applied to determine ten synthetic dyes in herbal medication. Full article
(This article belongs to the Special Issue Novel Achievements in Food Analytical Methodologies)
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Article
Identifying the Author Group of Malwares through Graph Embedding and Human-in-the-Loop Classification
Appl. Sci. 2021, 11(14), 6640; https://doi.org/10.3390/app11146640 - 20 Jul 2021
Viewed by 787
Abstract
Malware are developed for various types of malicious attacks, e.g., to gain access to a user’s private information or control of the computer system. The identification and classification of malware has been extensively studied in academic societies and many companies. Beyond the traditional [...] Read more.
Malware are developed for various types of malicious attacks, e.g., to gain access to a user’s private information or control of the computer system. The identification and classification of malware has been extensively studied in academic societies and many companies. Beyond the traditional research areas in this field, including malware detection, malware propagation analysis, and malware family clustering, this paper focuses on identifying the “author group” of a given malware as a means of effective detection and prevention of further malware threats, along with providing evidence for proper legal action. Our framework consists of a malware-feature bipartite graph construction, malware embedding based on DeepWalk, and classification of the target malware based on the k-nearest neighbors (KNN) classification. However, our KNN classifier often faced ambiguous cases, where it should say “I don’t know” rather than attempting to predict something with a high risk of misclassification. Therefore, our framework allows human experts to intervene in the process of classification for the final decision. We also developed a graphical user interface that provides the points of ambiguity for helping human experts to effectively determine the author group of the target malware. We demonstrated the effectiveness of our human-in-the-loop classification framework via extensive experiments using real-world malware data. Full article
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Article
Fabrication of Nanoporous Al by Vapor-Phase Dealloying: Morphology Features, Mechanical Properties and Model Predictions
Appl. Sci. 2021, 11(14), 6639; https://doi.org/10.3390/app11146639 - 20 Jul 2021
Cited by 2 | Viewed by 687
Abstract
The physical and chemical properties shown by nanoporous metals, related to their unique structure, make them very promising for application in several fields. Recently, vapor-phase dealloying has been reported as a method for the preparation of several non-noble nanoporous metals, alternatively to dealloying [...] Read more.
The physical and chemical properties shown by nanoporous metals, related to their unique structure, make them very promising for application in several fields. Recently, vapor-phase dealloying has been reported as a method for the preparation of several non-noble nanoporous metals, alternatively to dealloying in aqueous solutions. Using this approach, we have successfully fabricated nanoporous Al starting from an Al20Zn80 nanocomposite obtained by ball milling. The nanocomposite was annealed at 550 °C under high-vacuum conditions, and the difference in the vapor pressures allowed the selective removal of Zn by vapor-phase dealloying. The morphology of the resulting nanoporous material was analyzed by Scanning Electron Microscopy showing pores from few to thousands of nm; moreover, the nanoporous 3D structure was observed through Serial Block Face-Scanning Electron Microscopy. A specific surface area as high as 73 m2 g−1 was estimated by N2 physisorption measurements. In addition, a fractal model able to well reproduce the morphology of nanoporous Al was built. This model has been used for predicting mechanical properties which are in good agreement with experimental data obtained by nanoindentation. Full article
(This article belongs to the Special Issue Porous Materials: Design, Characterization, and Applications)
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Article
Effect of C-S-H Nucleating Agent on Cement Hydration
Appl. Sci. 2021, 11(14), 6638; https://doi.org/10.3390/app11146638 - 20 Jul 2021
Cited by 4 | Viewed by 723
Abstract
This work aims to study the effect of a nucleating agent on cement hydration. Firstly, the C-S-H crystal nucleation early strength agent (CNA) is prepared. Then, the effects of CNA on cement hydration mechanism, early strength enhancement effect, C-S-H content, 28-days hydration degree [...] Read more.
This work aims to study the effect of a nucleating agent on cement hydration. Firstly, the C-S-H crystal nucleation early strength agent (CNA) is prepared. Then, the effects of CNA on cement hydration mechanism, early strength enhancement effect, C-S-H content, 28-days hydration degree and 28-days fractal dimension of hydration products are studied by hydration kinetics calculation, resistivity test, BET specific surface area test and quantitative analysis of backscattered electron (BSE) images, respectively. The results show that CNA significantly improves the hydration degree of cement mixture, which is better than triethanolamine (TEA). CNA shortens the beginning time of the induction period by 49.3 min and the end time of the cement hydration acceleration period by 105.1 min than the blank sample. CNA increases the fractal dimension of hydration products, while TEA decreases the fractal dimension. CNA significantly improves the early strength of cement mortars; the 1-day and 3-days strength of cement mortars with CNA are more than the 3-days and 7-days strength of the blank sample. These results will provide a reference for the practical application of the C-S-H nucleating agent. Full article
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Communication
Superparamagnetic Fe/Au Nanoparticles and Their Feasibility for Magnetic Hyperthermia
Appl. Sci. 2021, 11(14), 6637; https://doi.org/10.3390/app11146637 - 20 Jul 2021
Cited by 1 | Viewed by 729
Abstract
Today, magnetic hyperthermia constitutes a complementary way to cancer treatment. This article reports a promising aspect of magnetic hyperthermia addressing superparamagnetic and highly Fe/Au core-shell nanoparticles. Those nanoparticles were prepared using a wet chemical approach at room temperature. We found that the as-synthesized [...] Read more.
Today, magnetic hyperthermia constitutes a complementary way to cancer treatment. This article reports a promising aspect of magnetic hyperthermia addressing superparamagnetic and highly Fe/Au core-shell nanoparticles. Those nanoparticles were prepared using a wet chemical approach at room temperature. We found that the as-synthesized core shells assembled with spherical morphology, including face-centered-cubic Fe cores coated and Au shells. The high-resolution transmission microscope images (HRTEM) revealed the formation of Fe/Au core/shell nanoparticles. The magnetic properties of the samples showed hysteresis loops with coercivity (HC) close to zero, revealing superparamagnetic-like behavior at room temperature. The saturation magnetization (MS) has the value of 165 emu/g for the as-synthesized sample with a Fe:Au ratio of 2:1. We also studied the feasibility of those core-shell particles for magnetic hyperthermia using different frequencies and different applied alternating magnetic fields. The Fe/Au core-shell nanoparticles achieved a specific absorption rate of 50 W/g under applied alternating magnetic field with amplitude 400 Oe and 304 kHz frequency. Based on our findings, the samples can be used as a promising candidate for magnetic hyperthermia for cancer therapy. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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