bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexible Sample Environments for the Investigation of Soft Matter at the European Spallation Source: Part I—The In Situ SANS/DLS Setup
Authors: Schmid Andreas Josef , Wiehemeier Lars , Jaksch Sebastian , Schneider Harald , Hiess Arno , Bögershausen Torsten , Widmann Tobias , Reitenbach Julija , Kreuzer Lucas P. , Kühnhammer Matthias , Löhmann Oliver , Brandl Georg , Frielinghaus Henrich , Müller-Buschbaum Peter , von Klitzing Regine , Hellweg Thomas
Published: April 2021

As part of the development of the new European Spallation Source (ESS) in Lund (Sweden), which will provide the most brilliant neutron beams worldwide, it is necessary to provide different sample environments with which the potential of the new source can be exploited as soon as possible from the start of operation. The overarching goal of the project is to reduce the downtimes of the instruments related to changing the sample environment by developing plug and play sample environments for different soft matter samples using the same general carrier platform and also providing full software integration and control by just using unified connectors. In the present article, as a part of this endeavor, the sample environment for in situ SANS and dynamic light scattering measurements is introduced.
Automatic Electromechanical Perturbator for Postural Control Analysis Based on Model Predictive Control
Authors: Pacheco Quiñones Daniel , Paterna Maria , De Benedictis Carlo
Published: April 2021

Objective clinical analyses are required to evaluate balance control performance. To this outcome, it is relevant to study experimental protocols and to develop devices that can provide reliable information about the ability of a subject to maintain balance. Whereas most of the applications available in the literature and on the market involve shifting and tilting of the base of support, the system presented in this paper is based on the direct application of an impulsive (short-lasting) force by means of an electromechanical device (named automatic perturbator). The control of such stimulation is rather complex since it requires high dynamics and accuracy. Moreover, the occurrence of several non-linearities, mainly related to the human–machine interaction, signals the necessity for robust control in order to achieve the essential repeatability and reliability. A linear electric motor, in combination with Model Predictive Control, was used to develop an automatic perturbator prototype. A test bench, supported by model simulations, was developed to test the architecture of the perturbation device. The performance of the control logic has been optimized by iterative tuning of the controller parameters, and the resulting behavior of the automatic perturbator is presented.
Heavy Metals in Urban Street Dust: Health Risk Assessment (Lublin City, E Poland)
Authors: Zgłobicki Wojciech , Telecka Małgorzata
Published: April 2021

Various pollutants, including heavy metals, present in street dust can pose a threat to the health of city dwellers. So far, studies on levels of this threat have been carried out mainly in large cities, characterised by considerable road traffic and industrial activity. This paper assesses the levels of hazard index and cancer risk for Cd, Cr, Cu, Ni, Pb and Zn contained in street dust collected in 2013 and 2018 at 62 points located in different parts of a small/medium-sized city (Lublin, E Poland). Heavy metals contents were analysed by means of XRF spectrometry (in the fraction <63 µm). Despite the fact that the concentrations of some elements (Zn, Cd and Cu) in street dust are 6–7 times higher than the geochemical background, this does not pose a risk of non-carcinogenic effects. The average hazard index (HI) for the individual elements reaches very low levels (<0.01). Cancer risk (CR) for adults is below the less strict limit of 10−4, and in the case of Pb, it is even lower than values of the order of 10−6, whereas for children, CR levels exceed the standards and are of the order of 10−4, except for Pb. For all metals except Cr, the health risk was higher in 2013 than in 2018.
Migration Groups: A Poorly Explored Point of View for Genetic Damage Assessment Using Comet Assay in Human Lymphocytes
Authors: Reynoso-Silva Mónica , Álvarez-Moya Carlos , Ramírez-Velasco Rafael , Sámano-León Alexis Gerardo , Arvizu-Hernández Erandi , Castañeda-Vásquez Hugo , Ruíz-Lopez Mario Alberto
Published: April 2021

A new point of view for genetic damage assessment using the comet assay is proposed based on the number of migration groups, the number of comets in each group, and the groups with the highest number of comets. Human lymphocytes were exposed to different concentrations of Methyl Methane Sulfonate (MMS), Maleic Hydrazide (MH), 2,4-Dichlorophenoxyacetic (2,4-D), and N-nitroso diethylamine (NDEA). Using comet assay, the migration means of the comets were determined and later grouped arbitrarily in migration groups with no higher differences than 1 µc. The number of migration groups, the number of comets in each group, and the groups with the highest number of comets (modes) were determined. All four of the genotoxic agents studied showed a significant increase (p < 0.05) in the tail length and the number of migration groups compared to the negative control. The number of migration groups did not show a significant variation between the four-genotoxic agents nor within their different concentrations. However, the comparison of the modes did show differences between the genotoxic agents, but not within the concentrations of a same genotoxic agent, which indicated a determined chemical interaction on the DNA. These parameters can improve the detection of genetic damage associated with certain genotoxic agents.
The CatWalk XT® Gait Analysis Is Closely Correlated with Tissue Damage after Cervical Spinal Cord Injury in Rats
Authors: Zheng Guoli , Younsi Alexander , Scherer Moritz , Riemann Lennart , Walter Johannes , Skutella Thomas , Unterberg Andreas , Zweckberger Klaus
Published: April 2021

Objective and consistent assessment of locomotion recovery remains challenging in rodent spinal cord injury (SCI). We, therefore, studied the validity and relevance of the CatWalk XT® gait analysis as a tool for assessing functional outcome in a clinically relevant cervical SCI model in rats. In total, 20 Wistar rats were randomly assigned to either a C6 clip compression/contusion SCI or a sham laminectomy. Locomotion recovery was assessed weekly using the CatWalk XT® gait analysis and the BBB open field score. Six weeks after SCI, the percentage of preserved spinal cord tissue was measured by glial fibrillary acidic protein (GFAP) immunohistochemistry (IHC) staining. Statistical analyses were performed to assess the correlation of the BBB and the percentage of preserved tissue with 30 different CatWalk XT® parameters. SCI caused a bilateral and significant functional impairment in all studied CatWalk XT® parameters. Similar to the BBB, a significant spontaneous recovery could be observed in most of the CatWalk XT® parameters in the following weeks. Correlation between the hindlimb CatWalk XT® parameters and the BBB was good (53% of r values > 0.6) while the correlation between the forelimb and the hindlimb CatWalk XT® parameters and the percentage of preserved tissue was even stronger (83% of r values > 0.6). The CatWalk XT® gait analysis is closely correlated with tissue damage after cervical contusion/compression SCI and can be used as an objective and consistent tool for assessing locomotion recovery.
Virtual Reality Rehabilitation and Exergames—Physical and Psychological Impact on Fall Prevention among the Elderly—A Literature Review
Authors: Piech Joanna , Czernicki Krzysztof
Published: April 2021

The present review is aimed at the effectiveness of virtual reality (VR) and exergames in the prevention of falls among the elderly. Falls become a significant problem in the aging population and lead to psychological, social, and physical impairment. Prevention of falls is crucial to the well-being of the elderly population and is one of the challenges of contemporary rehabilitation. Recently, in view of the threat of the SARS-CoV-2 pandemic, contactless methods of rehabilitation, including telerehabilitation, appear as valuable rehabilitation tools. This review is based on the PRISMA guidelines and was carried out in five databases: PubMed, Medline, Web of Science, Scopus, and PEDro. Twenty-one randomized controlled trials, focused on the application of VR and exergames in the prevention of falls, were included. This review suggests that VR training in rehabilitation appears to be a promising complement to traditional techniques of physiotherapy to improve specific physical outcomes. VR and exergames could be considered as a complement of standard physiotherapy and its possible continuation at home for elderly. However, further high-quality studies, with carefully designed protocols and proper blinding, are needed.
Effect of pH on the Economic Potential of Dark Fermentation Products from Used Disposable Nappies and Expired Food Products
Authors: Zagklis Dimitris , Papadionysiou Marina , Tsigkou Konstantina , Tsafrakidou Panagiota , Zafiri Constantina , Kornaros Michael
Published: April 2021

Used disposable nappies constitute a waste stream that has no established treatment method. The purpose of this study was the assessment of the dark fermentation of used disposable nappies and expired food products under different pH values. The biodegradable part of the used disposable nappies was recovered and co-fermented with expired food products originating from supermarkets. The recoverable economic potential of the process was examined for different volatile fatty acids exploitation schemes and process pH values. The process pH strongly affected the products, with optimum hydrogen production at pH 6 (4.05 NLH2/Lreactor), while the amount of produced volatile fatty acids was maximized at pH 7 (13.44 g/L). Hydrogen production was observed at pH as low as pH 4.5 (2.66 NLH2/Lreactor). The recoverable economic potential was maximized at two different pH values, with the first being pH 4.5 with minimum NaOH addition requirements (181, 138, and 296 EUR/ton VS of substrate for valorization of volatile fatty acids through microbial fuel cell, biodiesel production, and anaerobic digestion, respectively) and the second being pH 6, where the hydrogen production was maximized with the simultaneous production of high amounts of volatile fatty acids (191, 142, and 339 EUR/ton VS of substrate respectively).
Solar Potential in Saudi Arabia for Southward-Inclined Flat-Plate Surfaces
Authors: Farahat Ashraf , Kambezidis Harry D. , Almazroui Mansour , Ramadan Emad
Published: April 2021

The major objective of the present work is to investigate into the appropriate tilt angles of south-oriented solar panels in Saudi Arabia for maximum performance. This is done with the estimation of the annual energy sums received on surfaces with tilt angles in the range 15°–55° inclined to south at 82 locations covering all Saudi Arabia. The analysis shows that tilt angles of 20°, 25° and 30° towards south are the optimum ones depending on site. These optimum tilt angles define three distinct solar energy zones in Saudi Arabia. The variation of the energy sums in each energy zone on annual, seasonal and monthly basis is given; the analysis provides regression equations for the energy sums as function of time in each case. Furthermore, the spatial distribution of the annual global inclined solar energy in Saudi Arabia is shown in a solar map specially derived. The annual energy sums are found to vary between 1612 kWhm−2year−1 and 2977 kWhm−2year−1 across the country. Finally, the notion of a correction factor is introduced, defined, and employed. This factor can be used to correct energy values estimated by a reference ground albedo to those based on near-real ground albedo.
Bot Datasets on Twitter: Analysis and Challenges
Authors: Samper-Escalante Luis Daniel , Loyola-González Octavio , Monroy Raúl , Medina-Pérez Miguel Angel
Published: April 2021

The reach and influence of social networks over modern society and its functioning have created new challenges and opportunities to prevent the misuse or tampering of such powerful tools of social interaction. Twitter, a social networking service that specializes in online news and information exchange involving billions of users world-wide, has been infested by bots for several years. In this paper, we analyze both public and private databases from the literature of bot detection on Twitter. We summarize their advantages, disadvantages, and differences, recommending which is more suitable to work with depending on the necessities of the researcher. From this analysis, we present five distinct behaviors in automated accounts exhibited across all the bot datasets analyzed from these databases. We measure their level of presence in each dataset using a radar chart for visual comparison. Finally, we identify four challenges that researchers of bot detection on Twitter have to face when using these databases from the literature.
Investigation of the Optimum Display Luminance of an LCD Screen under Different Ambient Illuminances in the Evening
Authors: Zhou Ying , Shi Haoyue , Chen Qing-Wei , Ru Taotao , Zhou Guofu
Published: April 2021

Ambient illuminance and screen luminance have a significant influence on the visual fatigue and visual performance associated with the use of computers. The current study was conducted to investigate optimal screen luminance under different ambient illuminances and fit a curve of the optimum luminance of LCD screens under evening illumination. Thirty-three participants were assigned to rate screen brightness, visual comfort with screen luminance, satisfaction with ambient illuminance and visual fatigue under six screen luminance levels (3.87, 21.47, 42.74, 64.12, 84.77 and 106.7 cd/m2) combined with five ambient illuminance levels (0, 25, 50, 75 and 100 lx) in the evening. The results showed that optimum LCD screen luminance increased with increasing ambient illuminance. Moreover, ambient illuminance and screen luminance levels should be in the range of 13.08–62.16 lx and 20.63–75.15 cd/m2, respectively, to obtain the optimal subjective feelings of visual fatigue and visual comfort during the evening.
Mobile Learning Technologies for Education: Benefits and Pending Issues
Authors: Criollo-C Santiago , Guerrero-Arias Andrea , Jaramillo-Alcázar Ángel , Luján-Mora Sergio
Published: April 2021

Today’s world demands more efficient learning models that allow students to play a more active role in their education. Technology is having an impact on how instruction is delivered and how information is found and share. Until very recently, the educational models encouraged memorization as an essential learning skill. These days, technologies have changed the educational model and access to information. Knowledge is available online, mostly free, and easily accessible. Reading, sharing, listening and, doing are currently necessary skills for education. Mobile devices have become a complete set of applications, support, and help for educational organizations. By conducting an analysis of the behavior and use of mobile devices on current students, efficient educational applications can be developed. Although there are several initiatives for the use of mobile learning in education, there are also issues linked to this technology that must be addressed. In this work, we present the results of a literature review of mobile learning; the findings described are the result of the analysis of several articles obtained in three scientific repositories. This work also lists certain issues that, if properly addressed, can avoid possible complications to the implementation of this technology in education.
Experimental and Numerical Study on the Performance Change of a Simple Propeller Shape Using the Coanda Effect
Authors: Lee Ju-Han , Paik Kwang-Jun , Lee Soon-Hyun , Kim Gu-Hyeon , Cho Jun-Hui
Published: April 2021

In this study, a jet injection propeller was designed to increase its efficiency, and the results were compared by open water tests and numerical computations. Also, the change in shape of the slit and injection volume conditions, which are difficult to perform experiments with, were analyzed through computations. The jet injected from the blade surface generates additional thrust due to the Coanda effect, and the jet injection generates a moment in the direction of propeller rotation, resulting in a decrease in the total torque. Computations were performed for three slit heights. When the height of the slit is high, the efficiency of the propeller increases, even if the power of the pump required for jet injection is considered. The result was found to increase the efficiency by about 8.7%, even when the efficiency was compared under the condition of generating the same thrust by controlling the injection volume of the jet by designing a normal propeller that does not inject a jet.
Inferring Agents’ Goals from Observing Successful Traces
Authors: Lorthioir Guillaume , Inoue Katsumi , Bourgne Gauvain
Published: April 2021

Goal recognition is a sub-field of plan recognition that focuses on the goals of an agent. Current approaches in goal recognition have not yet tried to apply concept learning to a propositional logic formalism. In this paper, we extend our method for inferring an agent’s possible goal by observing this agent in a series of successful attempts to reach its goal and using concept learning on these observations. We propose an algorithm, LFST (Learning From Successful Traces), to produce concise hypotheses about the agent’s goal. We show that if such a goal exists, our algorithm always provides a possible goal for the agent, and we evaluate the performance of our algorithm in different settings. We compare it to another concept-learning algorithm that uses a formalism close to ours, and we obtain better results at producing the hypotheses with our algorithm. We introduce a way to use assumptions about the agent’s behavior and the dynamics of the environment, thus improving the agent’s goal deduction by optimizing the potential goals’ search space.
Resource-Based Quality Performance Estimation Method for Construction Operations
Authors: Park Young-Jun , Yi Chang-Yong
Published: April 2021

Construction quality is one of the primary management objectives relating to duration and cost for construction projects. Project managers struggle with minimizing duration and cost while maximizing quality for construction projects. In construction projects, duration and cost have management priorities. On the other hand, quality is considered a matter of achievement only when it reaches a certain level. Although the importance of quality control in construction management has been constantly discussed, it has still been sacrificed under the goal of shortening construction duration and reducing costs. This study presents a method for estimating the quantitative quality performance of construction operations in which the level of detail is breaking into the work task level for intuitive quality performance evaluation. For this purpose, quality weights of resources that have a proportional quality importance weight and quality performance indexes of resources are utilized for estimating the quantitative quality performance of construction operations. Quality performance estimation and the resource allocation optimization system is presented and validated using a construction simulation model.
The Effect of Yellow Tea Leaves Camellia sinensis on the Quality of Stored Chocolate Confectionery
Authors: Gramza-Michałowska Anna , Kulczyński Bartosz , Skopiec Marta , Kobus-Cisowska Joanna , Brzozowska Anna
Published: April 2021

Chocolate and tea leaves are considered the most valuable sources of highly bioactive polyphenols due to their potential anti-cancer properties and beneficial effects on the cardiovascular and nervous systems. The objective of the present study was the development of a sensory profiling modality that is correlated with the taste of the chocolate enriched with yellow tea phytochemicals. The additive concentration was optimized in white chocolate and the designed product was evaluated using the sensory profiling method. It was shown that the yellow tea extract in chocolate had a significant effect on the taste and color of the product. Addition of 2.0% yellow tea powdered extract increased the value of color acceptance and caused an intensification of the aromas, particularly the leafy taste, compared to the control samples. The next step of the study was to determine the influence of tea addition in white, milk and dark chocolate subjected to 6 months of storage. The designed chocolates were tested for their activity as antioxidants (DPPH, ABTS and ORAC assay) and cholinesterase inhibitors (AChE, BChE assay). It was confirmed that the yellow tea addition affected the activity of prepared chocolates with respect to radical scavenging activity and was highest for dark chocolate with yellow tea where the values were as follows: 4373 mg Tx/100 g (DPPH), 386 mg Tx/100 g (ABTS) and 4363 µM Tx/100 g (ORAC). An increase in the anti-radical activity of chocolate with yellow tea was found after 3 months of storage, but the subsequent 3 months of storage resulted in its reduction. AChE values ranged from 0.118 to 0.730 [µM eserine/g dw] and from 0.095 to 0.480 [µM eserine/g dw] for BChE assay. Total capacity to inhibit AChE and BChE differed depending on the type of chocolate and was negatively influenced by the half-year storage. Summarizing tested values for individual samples were higher, with increasing content of cocoa liquor and yellow tea extract in the product. The results of the research show that the use of yellow tea in confectionery is promising and may appoint a new direction in functional foods.
Modeling Heat Transport in Systems of Hydrate-Filled Sediments Using Residual Thermodynamics and Classical Nucleation Theory
Authors: Zarifi Mojdeh , Kvamme Bjørn , Kuznetsova Tatiana
Published: April 2021

As in any other phase transition, hydrate phase transition kinetics involves an implicit coupling of phase transition thermodynamic control and the associated dynamics of mass and heat transport. This work provides a brief overview of certain selected hydrate film growth models with an emphasis on analyzing the hydrate phase transition dynamics. Our analysis is based on the fundamental properties of hydrate and hydrate/liquid water interfaces derived from molecular modeling. We demonstrate that hydrate phase transitions involving water-dominated phases are characterized by heat transport several orders of magnitude faster than mass transport, strongly suggesting that any hydrate phase transition kinetic models based on heat transport will be entirely incorrect as far as thermodynamics is concerned. We therefore propose that theoretical studies focusing on hydrate nucleation and growth should be based on concepts that incorporate all the relevant transport properties. We also illustrate this point using the example of a fairly simplistic kinetic model, that of classical nucleation theory (CNT), modified to incorporate new models for mass transport across water/hydrate interfaces. A novel and consistent model suitable for the calculation of enthalpies is also discussed and appropriate calculations for pure components and relevant mixtures of carbon dioxide, methane, and nitrogen are demonstrated. This residual thermodynamic model for hydrate is consistent with the free energy model for hydrate and ensures that our revised CNT model is thermodynamically harmonious.
Aerodynamic Response and Running Posture Analysis When the Train Passes a Crosswind Region on a Bridge
Authors: Yan Jian , Chen Tefang , Deng E , Yang Weichao , Cheng Shu , Zhang Biming
Published: April 2021

Trains running on a bridge face more significant safety risks. Based on the Unsteady Reynolds-Averaged Navier–Stokes turbulence model, a three-dimensional Computational Fluid Dynamics computational model of the train–bridge–wind barrier was proposed in this study to measure the transient aerodynamic load of the train. The transient aerodynamic load was input into the wind–train–bridge coupling dynamic system to perform dynamic analysis of running safety. Significant fluctuations in the aerodynamic coefficients were found when the train entered and exited the wind barrier due to the dramatic change in flow pattern. The maximum value of the derailment coefficient decreased with the height of wind barriers, which hardly affected the wheel load reduction rate. The 2 m high wind barrier had no evident influence on the running posture of a general high-speed train, while the 4 m high wind barrier was proven to have better protection. Over-protection was found with an even higher wind barrier.
PV Benefits Assessment for PV-Powered Charging Stations for Electric Vehicles
Authors: Krim Youssef , Sechilariu Manuela , Locment Fabrice
Published: April 2021

Recently, the lift off point for the sales of electric vehicle (EV) was started with a significant increase. Therefore, convenient access to charging station infrastructure is required. The purpose of this work is to assess the role and benefits of photovoltaic (PV) for PV-powered charging infrastructures for EVs by a better energy management. This management is performed by a microgrid based on PV panels installed on roofs or car parking shades, EVs charging terminals, electrochemical stationary storage, and public grid connection. The aim is to define the economic aspects, feasibility and preliminary requirements for this system, in order to avoid overloading the power grid and guarantee a higher percentage of clean energy. The proposed methodology is presented through the modeling and development of a techno-economic tool for local stakeholders, allowing to manage and size EV charging stations, which is divided into three phases. The first phase informs local stakeholders on the necessary space and the maximum sizing as well as the generated cost to install a PV-powered charging station (PVCS). During the second phase, the total cost of the PVCS is adjusted according to the users’ budgets and needs. The third phase presents a detailed qualitative analysis of the user-defined configuration. In this phase, the main objective is to assess the performance of the PVCS, and then, to improve its sizing and its operating modes aiming at increasing the use of PV energy, while minimizing energy supplied by the power grid. In addition, it allows evaluating the PVCS performance by proposing an energy balance according to different charging scenarios (virtuous scenario, critical scenario, realistic scenario, and personalized scenario) and weather conditions. Moreover, this tool is reproducible in peri-urban area since it is able to handle any location.
Study on the Effect of Grinding Pressure on Material Removal Behavior Performed on a Self-Designed Passive Grinding Simulator
Authors: Liu Peng-Zhan , Zou Wen-Jun , Peng Jin , Song Xu-Dong , Xiao Fu-Ren
Published: April 2021

Passive grinding is a new rail grinding strategy. In this work, the influence of grinding pressure on the removal behaviors of rail material in passive grinding was investigated by using a self-designed passive grinding simulator. Meanwhile, the surface morphology of the rail and grinding wheel were observed, and the grinding force and temperature were measured during the experiment. Results show that the increase of grinding pressure leads to the rise of rail removal rate, i.e., grinding efficiency, surface roughness, residual stress, grinding force and grinding temperature. Inversely, the enhancement of grinding pressure and grinding force will reduce the grinding ratio, which indicates that service life of grinding wheel decreases. The debris presents dissimilar morphology under different grinding pressure, which reflects the distinction in grinding process. Therefore, for rail passive grinding, the appropriate grinding pressure should be selected to balance the grinding quality and the use of grinding wheel.
Machine Learning Methods with Noisy, Incomplete or Small Datasets
Authors: Caiafa Cesar F. , Sun Zhe , Tanaka Toshihisa , Marti-Puig Pere , Solé-Casals Jordi
Published: April 2021

In this article, we present a collection of fifteen novel contributions on machine learning methods with low-quality or imperfect datasets, which were accepted for publication in the special issue “Machine Learning Methods with Noisy, Incomplete or Small Datasets”, Applied Sciences (ISSN 2076-3417). These papers provide a variety of novel approaches to real-world machine learning problems where available datasets suffer from imperfections such as missing values, noise or artefacts. Contributions in applied sciences include medical applications, epidemic management tools, methodological work, and industrial applications, among others. We believe that this special issue will bring new ideas for solving this challenging problem, and will provide clear examples of application in real-world scenarios.
Reliability Analysis Based on a Gamma-Gaussian Deconvolution Degradation Modeling with Measurement Error
Authors: Rodríguez-Picón Luis Alberto , Méndez-González Luis Carlos , Romero-López Roberto , Pérez-Olguín Iván J. C. , Rodríguez-Borbón Manuel Iván , Valles-Rosales Delia Julieta
Published: April 2021

In most degradation tests, the measuring processes is affected by several conditions that may cause variation in the observed measures. As the measuring process is inherent to the degradation testing, it is important to establish schemes that define a certain level of permissible measurement error such that a robust reliability estimation can be obtained. In this article, an approach to deal with measurement error in degradation processes is proposed, the method focuses on studying the effect of such error in the reliability assessment. This approach considers that the true degradation is a function of the observed degradation and the measurement error. As the true degradation is not directly observed it is proposed to obtain an estimate based on a deconvolution operation, which considers the subtraction of random variables such as the observed degradation and the measurement error. Given that the true degradation is free of measurement error, the first-passage time distribution will be different from the observed degradation. For the establishment of a control mechanism, these two distributions are compared using different indices, which account to describe the differences between the observed and true degradation. By defining critical levels of these indices, the reliability assessment may be obtained under a known level of measurement error. An illustrative example based on a fatigue-crack growth dataset is presented to illustrate the applicability of the proposed scheme, the reliability assessment is developed, and some important insights are provided.
Remediation of Metal/Metalloid-Polluted Soils: A Short Review
Authors: Raffa Carla Maria , Chiampo Fulvia , Shanthakumar Subramanian
Published: April 2021

The contamination of soil by heavy metals and metalloids is a worldwide problem due to the accumulation of these compounds in the environment, endangering human health, plants, and animals. Heavy metals and metalloids are normally present in nature, but the rise of industrialization has led to concentrations higher than the admissible ones. They are non-biodegradable and toxic, even at very low concentrations. Residues accumulate in living beings and become dangerous every time they are assimilated and stored faster than they are metabolized. Thus, the potentially harmful effects are due to persistence in the environment, bioaccumulation in the organisms, and toxicity. The severity of the effect depends on the type of heavy metal or metalloid. Indeed, some heavy metals (e.g., Mn, Fe, Co, Ni) at very low concentrations are essential for living organisms, while others (e.g., Cd, Pb, and Hg) are nonessential and are toxic even in trace amounts. It is important to monitor the concentration of heavy metals and metalloids in the environment and adopt methods to remove them. For this purpose, various techniques have been developed over the years: physical remediation (e.g., washing, thermal desorption, solidification), chemical remediation (e.g., adsorption, catalysis, precipitation/solubilization, electrokinetic methods), biological remediation (e.g., biodegradation, phytoremediation, bioventing), and combined remediation (e.g., electrokinetic–microbial remediation; washing–microbial degradation). Some of these are well known and used on a large scale, while others are still at the research level. The main evaluation factors for the choice are contaminated site geology, contamination characteristics, cost, feasibility, and sustainability of the applied process, as well as the technology readiness level. This review aims to give a picture of the main techniques of heavy metal removal, also giving elements to assess their potential hazardousness due to their concentrations.
A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear
Authors: Pecora Rosario
Published: April 2021

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.
A Novel Type of Wall-Climbing Robot with a Gear Transmission System Arm and Adhere Mechanism Inspired by Cicada and Gecko
Authors: Bian Shiyuan , Xu Feng , Wei Yuliang , Kong Deyi
Published: April 2021

To support the inspections of different contact walls (rough and smooth), a novel type of wall-climbing robot was proposed. Its design embodied a new gear transmission system arm and an adherence mechanism inspired by cicadas and geckos. The actuating structure consisted of a five-bar link and a gear transmission for the arm stretching, which was driven by the servos. The linkers and gears formed the palm of this robot for climbing on a line. Moreover, the robot’s adherence method for the rough surfaces used bionic spine materials inspired by the cicada. For smooth surface, a bionic adhesion material was proposed inspired by the gecko. To assess the adherence mechanism of the cicada and gecko, the electron microscope images of the palm of the cicada and gecko were obtained by an electron microscope. The 3D printing technology and photolithography technology were utilized to manufacture the robot’s structures. The adherence force experiments demonstrated the bionic spines and bionic materials achieved good climbing on cloth, stones, and glass surfaces. Furthermore, a new gait for the robot was designed to ensure its stability. The dynamic characteristics of the robot’s gear transmission were obtained.
Organic Molecular Tracers in PM2.5 at Urban Sites during Spring and Summer in Japan: Impact of Secondary Organic Aerosols on Water-Soluble Organic Carbon
Authors: Ikemori Fumikazu , Nishimura Rie , Saito Shinji , Akiyama Masayuki , Yamamoto Shigekazu , Iijima Akihiro , Sugata Seiji
Published: April 2021

To understand the characteristics of secondary organic aerosols (SOAs) and estimate their impact on water-soluble organic carbon (WSOC) in urban areas in Japan, we measured 17 organic tracers using gas chromatography–mass spectrometry from particulate matter with an aerodynamic diameter smaller than 2.5 μm collected at five urban sites in Japan during spring and summer. Most anthropogenic, monoterpene-derived, and isoprene-derived SOA tracers showed meaningful correlations with potential ozone in both these seasons. These results indicate that oxidants play an important role in SOAs produced during both seasons in urban cities in Japan. WSOC was significantly affected by anthropogenic and monoterpene-derived SOAs during spring and three SOA groups during summer at most of the sites sampled. The total estimated secondary organic carbons (SOCs), including mono-aromatic, di-aromatic, monoterpene-derived, and isoprene-derived SOCs, could explain the WSOC fractions of 39–63% in spring and 46–54% in summer at each site. Notably, monoterpene-derived and mono-aromatic SOCs accounted for most of the total estimated SOCs in both spring (85–93%) and summer (75–82%) at each site. These results indicate that SOAs significantly impact WSOC concentrations during both these seasons at urban sites in Japan.
Proteolytic Cleavage of Receptor Tyrosine Kinases
Authors: Huang Hao
Published: April 2021

The receptor tyrosine kinases (RTKs) are a large family of cell-surface receptors, which are essential components of signal transduction pathways. There are more than fifty human RTKs that can be grouped into multiple RTK subfamilies. RTKs mediate cellular signaling transduction, and they play important roles in the regulation of numerous cellular processes. The dysregulation of RTK signaling is related to various human diseases, including cancers. The proteolytic cleavage phenomenon has frequently been found among multiple receptor tyrosine kinases. More and more information about proteolytic cleavage in RTKs has been discovered, providing rich insight. In this review, we summarize research about different aspects of RTK cleavage, including its relation to cancer, to better elucidate this phenomenon. This review also presents proteolytic cleavage in various members of the RTKs.
Imbalance in Coagulation/Fibrinolysis Inhibitors Resulting in Extravascular Thrombin Generation in Gliomas of Varying Levels of Malignancy
Authors: Wojtukiewicz Marek Z. , Mysliwiec Marta , Matuszewska Elwira , Sulkowski Stanislaw , Zimnoch Lech , Politynska Barbara , Wojtukiewicz Anna M. , Tucker Stephanie C. , Honn Kenneth V.
Published: April 2021

Neoplastic processes are integrally related to disturbances in the mechanisms regulating hemostatic processes. Brain tumors, including gliomas, are neoplasms associated with a significantly increased risk of thromboembolic complications, affecting 20–30% of patients. As gliomas proliferate, they cause damage to the brain tissue and vascular structures, which leads to the release of procoagulant factors into the systemic circulation, and hence systemic activation of the blood coagulation system. Hypercoagulability in cancer patients may be, at least in part, a result of the inadequate activity of coagulation inhibitors. The aim of the study was to evaluate the expression of the inhibitors of the coagulation and fibrinolysis systems (tissue factor pathway inhibitor, TFPI; tissue factor pathway inhibitor-2 TFPI-2; protein C, PC; protein S, PS, thrombomodulin, TM; plasminogen activators inhibitor, PAI-1) in gliomas of varying degrees of malignancy. Immunohistochemical studies were performed on 40 gliomas, namely on 13 lower-grade (G2) gliomas (8 astrocytomas, 5 oligodendrogliomas) and 27 high-grade gliomas (G3–12 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas; G4–11 glioblastomas). A strong expression of TFPI-2, PS, TM, PAI-1 was observed in lower-grade gliomas, while an intensive color immunohistochemical (IHC) reaction for the presence of TFPI antigens was detected in higher-grade gliomas. The presence of PC antigens was found in all gliomas. Prothrombin fragment 1+2 was observed in lower- and higher-grade gliomas reflecting local activation of blood coagulation. Differences in the expression of coagulation/fibrinolysis inhibitors in the tissues of gliomas with varying degrees of malignancy may be indicative of their altered role in gliomas, going beyond that of their functions in the hemostatic system.
Correlated Motions of Conserved Polar Motifs Lay out a Plausible Mechanism of G Protein-Coupled Receptor Activation
Authors: Mitra Argha , Sarkar Arijit , Szabó Márton Richárd , Borics Attila
Published: April 2021

Recent advancements in the field of experimental structural biology have provided high-resolution structures of active and inactive state G protein-coupled receptors (GPCRs), a highly important pharmaceutical target family, but the process of transition between these states is poorly understood. According to the current theory, GPCRs exist in structurally distinct, dynamically interconverting functional states of which populations are shifted upon binding of ligands and intracellular signaling proteins. However, explanation of the activation mechanism, on an entirely structural basis, gets complicated when multiple activation pathways and active receptor states are considered. Our unbiased, atomistic molecular dynamics simulations of the μ opioid receptor (MOP) revealed that transmission of external stimulus to the intracellular surface of the receptor is accompanied by subtle, concerted movements of highly conserved polar amino acid side chains along the 7th transmembrane helix. This may entail the rearrangement of polar species and the shift of macroscopic polarization in the transmembrane domain, triggered by agonist binding. Based on our observations and numerous independent indications, we suggest amending the widely accepted theory that the initiation event of GPCR activation is the shift of macroscopic polarization between the ortho- and allosteric binding pockets and the intracellular G protein-binding interface.
Novel Chemically Modified Curcumin (CMC) Derivatives Inhibit Tyrosinase Activity and Melanin Synthesis in B16F10 Mouse Melanoma Cells
Authors: Goenka Shilpi , Johnson Francis , Simon Sanford R.
Published: April 2021

Skin hyperpigmentation disorders arise due to excessive production of the macromolecular pigment melanin catalyzed by the enzyme tyrosinase. Recently, the therapeutic use of curcumin for inhibiting tyrosinase activity and production of melanin have been recognized, but poor stability and solubility have limited its use, which has inspired synthesis of curcumin analogs. Here, we investigated four novel chemically modified curcumin (CMC) derivatives (CMC2.14, CMC2.5, CMC2.23 and CMC2.24) and compared them to the parent compound curcumin (PC) for inhibition of in vitro tyrosinase activity using two substrates for monophenolase and diphenolase activities of the enzyme and for diminution of cellular melanogenesis. Enzyme kinetics were analyzed using Lineweaver-Burk and Dixon plots and nonlinear curve-fitting to determine the mechanism for tyrosinase inhibition. Copper chelating activity, using pyrocatechol violet dye indicator assay, and antioxidant activity, using a DPPH radical scavenging assay, were also conducted. Next, the capacity of these derivatives to inhibit tyrosinase-catalyzed melanogenesis was studied in B16F10 mouse melanoma cells and the mechanisms of inhibition were elucidated. Inhibition mechanisms were studied by measuring intracellular tyrosinase activity, cell-free and intracellular α-glucosidase enzyme activity, and effects on MITF protein level and cAMP maturation factor. Our results showed that CMC2.24 showed the greatest efficacy as a tyrosinase inhibitor of all the CMCs and was better than PC as well as a popular tyrosinase inhibitor-kojic acid. Both CMC2.24 and CMC2.23 inhibited tyrosinase enzyme activity by a mixed mode of inhibition with a predominant competitive mode. In addition, CMC2.24 as well as CMC2.23 showed a comparable robust efficacy in inhibiting melanogenesis in cultured melanocytes. Furthermore, after removal of CMC2.24 or CMC2.23 from the medium, we could demonstrate a partial recovery of the suppressed intracellular tyrosinase activity in the melanocytes. Our results provide a proof-of-principle for the novel use of the CMCs that shows them to be far superior to the parent compound, curcumin, for skin depigmentation.
Chitosan Functionalized Magnetic Nanoparticles to Provide Neural Regeneration and Recovery after Experimental Model Induced Peripheral Nerve Injury
Authors: Pop Nadina Liana , Nan Alexandrina , Urda-Cimpean Andrada Elena , Florea Adrian , Toma Vlad Alexandru , Moldovan Remus , Decea Nicoleta , Mitrea Daniela Rodica , Orasan Remus
Published: April 2021

(1) Background: Peripheral nerve injuries have a great impact on a patient’s quality of life and a generally poor outcome regarding functional recovery. Lately, studies have focused on different types of nanoparticles and various natural substances for the treatment of peripheral nerve injuries. This is the case of chitosan, a natural compound from the crustaceans’ exoskeleton. The present study proposes to combine chitosan benefic properties to the nanoparticles’ ability to transport different substances to specific locations and evaluate the effects of magnetic nanoparticles functionalized with chitosan (CMNPs) on peripheral nerve injuries’ rehabilitation by using an in vivo experimental model. (2) Methods: CMNPs treatment was administrated daily, orally, for 21 days to rats subjected to right sciatic nerve lesion and compared to the control group (no treatment) by analyzing the sciatic functional index, pain level, body weight, serum nerve growth factor levels and histology, TEM and EDX analysis at different times during the study. (3) Results: Animals treated with CMNPs had a statistically significant functional outcome compared to the control group regarding: sciatic functional index, pain-like behavior, total body weight, which were confirmed by the histological and TEM images. (4) Conclusions: The results of the study suggest that CMNPs appear to be a promising treatment method for peripheral nerve injuries.