bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutated p53 in HGSC—From a Common Mutation to a Target for Therapy
Authors: Saleh Aya , Perets Ruth
Published: July 2021

Mutations in tumor suppressor gene TP53, encoding for the p53 protein, are the most ubiquitous genetic variation in human ovarian HGSC, the most prevalent and lethal histologic subtype of epithelial ovarian cancer (EOC). The majority of TP53 mutations are missense mutations, leading to loss of tumor suppressive function of p53 and gain of new oncogenic functions. This review presents the clinical relevance of TP53 mutations in HGSC, elaborating on several recently identified upstream regulators of mutant p53 that control its expression and downstream target genes that mediate its roles in the disease. TP53 mutations are the earliest genetic alterations during HGSC pathogenesis, and we summarize current information related to p53 function in the pathogenesis of HGSC. The role of p53 is cell autonomous, and in the interaction between cancer cells and its microenvironment. We discuss the reduction in p53 expression levels in tumor associated fibroblasts that promotes cancer progression, and the role of mutated p53 in the interaction between the tumor and its microenvironment. Lastly, we discuss the potential of TP53 mutations to serve as diagnostic biomarkers and detail some more advanced efforts to use mutated p53 as a therapeutic target in HGSC.
Modified Red Mud Catalyst for Volatile Organic Compounds Oxidation
Authors: Pande Gaurav , Selvakumar Subramanian , Ciotonea Carmen , Giraudon Jean-Marc , Lamonier Jean-François , Batra Vidya S.
Published: July 2021

Red mud waste from the aluminium industry was modified by leaching using hydrochloric acid or oxalic acid with additives, followed by precipitation or evaporation. The prepared catalysts were characterized in detail and tested for toluene total oxidation. The samples prepared by precipitation of the leachate by adding a base gave a much better performance in catalytic oxidation than the ones prepared by just evaporating the leachate. These improved performances can be correlated to the enhanced textural and redox properties of the catalysts due to the better dispersion and higher enrichment of Fe oxides at their surface. The best performing catalyst had a light-off temperature of around 310 °C and complete oxidation took place at around 380 °C.
Catalytic Effect of 1,4-Dioxane on the Kinetics of the Oxidation of Iodide by Dicyanobis(bipyridine)iron(III) in Water
Authors: Khattak Rozina , Khan Muhammad Sufaid , Iqbal Zahoor , Ullah Rizwan , Khan Abbas , Summer Shazia , Noreen Hamsa , Zahoor Muhammad , El-Bahy Salah M. , Batiha Gaber El-Saber
Published: July 2021

Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today’s photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. This article discusses the potential use of dicyanobis(bipyridine)iron(III) to oxidize iodide as a sensitizer in DSSCs. However, it is critical to understand the kinetics of this essential process in order to understand the mechanism of electron transport. The oxidation of iodide by dicyanobis(bipyridine)iron(III) in three reaction media was studied: water, 10% v/v 1,4-dioxane-water, and 20% v/v 1,4-dioxane-water. The reaction was carried out in a regular laboratory setting, with no special sensitive conditions or the use of expensive materials, making it a cost-effective and practical method. Dicyanobis(bipyridine)iron(III) oxidized iodide in selected media at 0.06 M ionic strength and constant temperature. The reaction was subjected to a spectrophotometric analysis. The data were acquired by measuring the rise in visible absorbance as a function of time after the formation of dicyanobis(bipyridine)iron(II). The reaction proceeded with an overall fractional (0.5), first order, and third order in water, 10% media, and 20% media, respectively. The presence of dicyanobis(bipyridine)iron(III) in either of the reaction media had no effect on the rate. The effect of protons (H+) on the rate constant indicated resistance in water and catalysis in dioxane-water media containing 10–20% dioxane. When the ionic strength was raised, there was no change in the rate constant in water, but there was a deceleration in both binary solvent media. In an aqueous medium, the thermodynamic parameters of activation were computed as Ea 46.23 kJ mol−1, 24.62 M s−1, ΔH# 43.76 kJ mol−1, ΔS# −226.5 J mol−1 K−1, and ΔG# 111.26 kJ mol−1 (25 °C). By increasing the rate of the reaction to its maximum, this study discovered the binary solvent media with the highest catalytic efficiency, i.e., 20% v/v 1,4-dioxane-water, which may increase the efficiency of DSSCs without using any expensive material or unusual experimental conditions.
Changes in Chromatin Organization Eradicate Cellular Stress Resilience to UVA/B Light and Induce Premature Aging
Authors: Vasileva Bela , Staneva Dessislava , Krasteva Natalia , Miloshev George , Georgieva Milena
Published: July 2021

Complex interactions among DNA and nuclear proteins maintain genome organization and stability. The nuclear proteins, particularly the histones, organize, compact, and preserve the stability of DNA, but also allow its dynamic reorganization whenever the nuclear processes require access to it. Five histone classes exist and they are evolutionarily conserved among eukaryotes. The linker histones are the fifth class and over time, their role in chromatin has been neglected. Linker histones interact with DNA and the other histones and thus sustain genome stability and nuclear organization. Saccharomyces cerevisiae is a brilliant model for studying linker histones as the gene for it is a single-copy and is non-essential. We, therefore, created a linker histone-free yeast strain using a knockout of the relevant gene and traced the way cells age chronologically. Here we present our results demonstrating that the altered chromatin dynamics during the chronological lifespan of the yeast cells with a mutation in ARP4 (the actin-related protein 4) and without the gene HHO1 for the linker histone leads to strong alterations in the gene expression profiles of a subset of genes involved in DNA repair and autophagy. The obtained results further prove that the yeast mutants have reduced survival upon UVA/B irradiation possibly due to the accelerated decompaction of chromatin and impaired proliferation. Our hypothesis posits that the higher-order chromatin structure and the interactions among chromatin proteins are crucial for the maintenance of chromatin organization during chronological aging under optimal and UVA-B stress conditions.
Antiviral Activity of Influenza A Virus Defective Interfering Particles against SARS-CoV-2 Replication In Vitro through Stimulation of Innate Immunity
Authors: Rand Ulfert , Kupke Sascha Young , Shkarlet Hanna , Hein Marc Dominique , Hirsch Tatjana , Marichal-Gallardo Pavel , Cicin-Sain Luka , Reichl Udo , Bruder Dunja
Published: July 2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) emerged in late 2019 and resulted in a devastating pandemic. Although the first approved vaccines were already administered by the end of 2020, worldwide vaccine availability is still limited. Moreover, immune escape variants of the virus are emerging against which the current vaccines may confer only limited protection. Further, existing antivirals and treatment options against COVID-19 show only limited efficacy. Influenza A virus (IAV) defective interfering particles (DIPs) were previously proposed not only for antiviral treatment of the influenza disease but also for pan-specific treatment of interferon (IFN)-sensitive respiratory virus infections. To investigate the applicability of IAV DIPs as an antiviral for the treatment of COVID-19, we conducted in vitro co-infection experiments with cell culture-derived DIPs and the IFN-sensitive SARS-CoV-2 in human lung cells. We show that treatment with IAV DIPs leads to complete abrogation of SARS-CoV-2 replication. Moreover, this inhibitory effect was dependent on janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling. Further, our results suggest boosting of IFN-induced antiviral activity by IAV DIPs as a major contributor in suppressing SARS-CoV-2 replication. Thus, we propose IAV DIPs as an effective antiviral agent for treatment of COVID-19, and potentially also for suppressing the replication of new variants of SARS-CoV-2.
Antioxidant Supplements versus Health Benefits of Brief/Intermittent Exposure to Potentially Toxic Physical or Chemical Agents
Authors: Franco Rafael , Casanovas Berta , Camps Jordi , Navarro Gemma , Martínez-Pinilla Eva
Published: July 2021

Although antioxidants can act locally to react with an oxidant, oral administration of “antioxidants” is quite useless in treating oxidative stress in tissues. Furthermore, it does not make sense to consider a vitamin as an antioxidant, but vitamin B3 leads to the in vivo formation of compounds that are essential for reducing this stress. A rigorous treatment of the subject indicates that to deal with oxidative stress, the most direct approach is to enhance the innate antioxidant mechanisms. The question is whether this is possible through daily activities. Diets can contain the necessary components for these mechanisms or may induce the expression of the genes involved in them. Another possibility is that pro-oxidant molecules in food increase the sensitivity and power of the detoxification pathways. This option is based on well-known DNA repair mechanisms after exposure to radiation (even from the Sun), or strong evidence of induction of antioxidant capacity after exposure to powerful pro-oxidants such as H2O2. More experimental work is required to test whether some molecules in food can increase the expression of antioxidant enzymes and/or improve antioxidant mechanisms. Identifying effective molecules to achieve such antioxidant power is critical to the food and nutraceutical industries. The potential of diet-based interventions to combat oxidative stress must be viewed from a new perspective.
Performing Learning Analytics via Generalised Mixed-Effects Trees
Authors: Fontana Luca , Masci Chiara , Ieva Francesca , Paganoni Anna Maria
Published: July 2021

Nowadays, the importance of educational data mining and learning analytics in higher education institutions is being recognised. The analysis of university careers and of student dropout prediction is one of the most studied topics in the area of learning analytics. From the perspective of estimating the likelihood of a student dropping out, we propose an innovative statistical method that is a generalisation of mixed-effects trees for a response variable in the exponential family: generalised mixed-effects trees (GMET). We performed a simulation study in order to validate the performance of our proposed method and to compare GMET to classical models. In the case study, we applied GMET to model undergraduate student dropout in different courses at Politecnico di Milano. The model was able to identify discriminating student characteristics and estimate the effect of each degree-based course on the probability of student dropout.
Loss of Lymphotoxin Alpha-Expressing Memory B Cells Correlates with Metastasis of Human Primary Melanoma
Authors: Werner Franziska , Wagner Christine , Simon Martin , Glatz Katharina , Mertz Kirsten D. , Läubli Heinz , Richtig Erika , Griss Johannes , Wagner Stephan N.
Published: July 2021

Activated antigen-experienced B cells play an unexpected complex role in anti-tumor immunity in human melanoma patients. However, correlative studies between B cell infiltration and tumor progression are limited by the lack of distinction between functional B cell subtypes. In this study, we examined a series of 59 primary and metastatic human cutaneous melanoma specimens with B cell infiltration. Using seven-color multiplex immunohistochemistry and automated tissue imaging and analysis, we analyzed the spatiotemporal dynamics of three major antigen-experienced B cell subpopulations expressing lymphotoxin alpha (LTA/TNFSF1) or interleukin-10 (IL-10) outside tertiary lymphoid structures. The expression of both LTA and IL-10 was not restricted to a particular B cell subtype. In primary melanomas, these cells were predominantly found at the invasive tumor-stroma front and, in metastatic melanomas, they were also found in the intratumoral stroma. In primary melanomas, decreased densities of LTA+ memory-like and, to a lesser extent, activated B cells were associated with metastasis. Compared with metastatic primary tumors, B cell infiltrates in melanoma metastases were enriched in both LTA+ memory-like and LTA+ activated B cells, but not in any of the IL-10+ B cell subpopulations. Melanoma disease progression shows distinct dynamics of functional B cell subpopulations, with the regulation of LTA+ B cell numbers being more significant than IL-10+ B cell subpopulations.
Improving Recommendations for Online Retail Markets Based on Ontology Evolution
Authors: Alaa Rana , Gawish Mariam , Fernández-Veiga Manuel
Published: July 2021

The semantic web is considered to be an extension of the present web. In the semantic web, information is given with well-defined meanings, and thus helps people worldwide to cooperate together and exchange knowledge. The semantic web plays a significant role in describing the contents and services in a machine-readable form. It has been developed based on ontologies, which are deemed the backbone of the semantic web. Ontologies are a key technique with which semantics are annotated, and they provide common comprehensible foundation for resources on the semantic web. The use of semantics and artificial intelligence leads to what is known to be “Smarter Web”, where it will be easy to retrieve what customers want to see on e-commerce platforms, and thus will help users save time and enhance their search for the products they need. The semantic web is used as well as webs 3.0, which helps enhancing systems performance. Previous personalized recommendation methods based on ontologies identify users’ preferences by means of static snapshots of purchase data. However, as the user preferences evolve with time, the one-shot ontology construction is too constrained for capturing individual diverse opinions and users’ preferences evolution over time. This paper will present a novel recommendation system architecture based on ontology evolution, the proposed subsystem architecture for ontology evolution. Furthermore, the paper proposes an ontology building methodology based on a semi-automatic technique as well as development of online retail ontology. Additionally, a recommendation method based on the ontology reasoning is proposed. Based on the proposed method, e-retailers can develop a more convenient product recommendation system to support consumers’ purchase decisions.
Dynamic Frequency Support for Low Inertia Power Systems by Renewable Energy Hubs with Fast Active Power Regulation
Authors: Rueda Torres Jose , Kumar Nidarshan Veera , Rakhshani Elyas , Ahmad Zameer , Adabi Ebrahim , Palensky Peter , van der Meijden Mart
Published: July 2021

This paper concerns the feasibility of Fast Active Power Regulation (FAPR) in renewable energy hubs. Selected state-of-the-art FAPR strategies are applied to various controllable devices within a hub, such as a solar photovoltaic (PV) farm and an electrolyzer acting as a responsive load. Among the selected strategies are droop-based FAPR, droop derivative-based FAPR, and virtual synchronous power (VSP)-based FAPR. The FAPR-supported hub is interconnected with a test transmission network, modeled and simulated in a real-time simulation electromagnetic transient (EMT) environment to study a futuristic operating condition of the high-voltage infrastructure covering the north of the Netherlands. The real-time EMT simulations show that the FAPR strategies (especially the VSP-based FAPR) can successfully help to significantly and promptly limit undesirable large instantaneous frequency deviations.
Analyzing Visual Attention of People with Intellectual Disabilities during Virtual Reality-Based Job Training
Authors: Hong Sungjin , Shin Heesook , Gil Younhee , Jo Junghee
Published: July 2021

Virtual reality (VR) has proven an effective means of job training for people with intellectual disabilities who may experience difficulties in learning. However, it is unlikely for them to successfully complete a certain task using only VR-based job training contents without receiving supplemental help from others. Accordingly, to increase the effectiveness of virtual job training for people with intellectual disabilities in training situations in which they may experience difficulty and become unable to proceed further, the contents of the training program need to automatically identify such moments and provide support so that they may correctly perform the task. To identity the moment of intervention, we conducted an experiment (n = 21) to collect eye tracking data of people with intellectual disabilities while performing VR-based barista training. We measured eye scanning patterns to identify any difference between people with intellectual disabilities who complete a given step independently and those who request intervention. We found that the information about the types of fixated objects did not help to identify any difference, but the information about eye transition, eye movements between two different areas of interest, was useful in identifying the difference. Our findings provide implications for identifying the moment of intervention for people with intellectual disabilities.
Survey of Millimeter-Wave Propagation Measurements and Models in Indoor Environments
Authors: Al-Saman Ahmed , Cheffena Michael , Elijah Olakunle , Al-Gumaei Yousef A. , Abdul Rahim Sharul Kamal , Al-Hadhrami Tawfik
Published: July 2021

The millimeter-wave (mmWave) is expected to deliver a huge bandwidth to address the future demands for higher data rate transmissions. However, one of the major challenges in the mmWave band is the increase in signal loss as the operating frequency increases. This has attracted several research interests both from academia and the industry for indoor and outdoor mmWave operations. This paper focuses on the works that have been carried out in the study of the mmWave channel measurement in indoor environments. A survey of the measurement techniques, prominent path loss models, analysis of path loss and delay spread for mmWave in different indoor environments is presented. This covers the mmWave frequencies from 28 GHz to 100 GHz that have been considered in the last two decades. In addition, the possible future trends for the mmWave indoor propagation studies and measurements have been discussed. These include the critical indoor environment, the roles of artificial intelligence, channel characterization for indoor devices, reconfigurable intelligent surfaces, and mmWave for 6G systems. This survey can help engineers and researchers to plan, design, and optimize reliable 5G wireless indoor networks. It will also motivate the researchers and engineering communities towards finding a better outcome in the future trends of the mmWave indoor wireless network for 6G systems and beyond.
Modeling of Small Productive Processes for the Operation of a Microgrid
Authors: Espín-Sarzosa Danny , Palma-Behnke Rodrigo , Valencia Felipe
Published: July 2021

Small productive processes (SPPs) are promising drivers that promote the economic use of energy in microgrids (MGs). Both the complex nature of the SPPs and voltage variations make the operation of MGs challenging, since the quality of an energy management system’s (EMS) decisions depend on its characterization. The aim of this work is to propose a methodology for SPPs modeling, and to consider the influence of voltage on load consumption, which has general validity, and can be efficiently integrated into different MG EMS approaches. For this purpose, a novel extended multi-zone ZIP approach for the characterization of SPP loads and sensitivity to voltage changes is proposed. The associated framework herein presented was assessed using actual data collected from SPPs installed near the city of Arica, in northern Chile. The results showed that the proposed methodology was capable of representing the complex load behavior of the SPPs, properly considering the voltage influence. These results were compared with those obtained through common approaches found in the literature. The effectiveness of the proposed approach in representing SPP loads and their sensitivity to voltage changes was verified. The proposed scheme can be efficiently integrated into a wide range of EMS for MGs that include SPPs.
The Influence of Introducing Autonomous Vehicles on Conventional Transport Modes and Travel Time
Authors: Hamadneh Jamil , Esztergár-Kiss Domokos
Published: July 2021

Introducing autonomous vehicles (AVs) on the market is likely to bring changes in the mobility of travelers. In this work, extensive research is conducted to study the impact of different levels of automation on the mobility of people, and full driving automation needs further study because it is still under development. The impacts of AVs on travel behavior can be studied by integrating AVs into activity-based models. The contribution of this study is the estimation of AVs’ impacts on travelers’ mobility when different travel demands are provided, and also the estimation of AVs’ impact on the modal share considering the different willingness of pay to travel by AVs. This study analyses the potential impacts of AVs on travel behavior by investigating a sample of 8500 travelers who recorded their daily activity plans in Budapest, Hungary. Three scenarios are derived to study travel behavior and to find the impacts of the AVs on the conventional transport modes. The scenarios include (1) a simulation of the existing condition, (2) a simulation of AVs as a full replacement for conventional transport modes, and (3) a simulation of the AVs with conventional transport modes concerning different marginal utilities of travel time in AVs. The simulations are done by using the Multi-Agent Transport Simulation (MATSim) open-source software, which applies a co-evolutionary optimization algorithm. Using the scenarios in the study, we develop a base model, determine the required fleet size of AVs needed to fulfill the demand of the different groups of travelers, and predict the new modal shares of the transport modes when AVs appear on the market. The results demonstrate that the travelers are exposed to a reduction in travel time once conventional transport modes are replaced by AVs. The impact of the value of travel time (VOT) on the usage of AVs and the modal share is demonstrated. The decrease in the VOT of AVs increases the usage of AVs, and it particularly decreases the usage of cars even more than other transport modes. AVs strongly affect the public transport when the VOT of AVs gets close to the VOT of public transport. Finally, the result shows that 1 AV can replace 7.85 conventional vehicles with acceptable waiting time.
Thermal Analysis of the Medium Voltage Cable
Authors: Szczegielniak Tomasz , Kusiak Dariusz , Jabłoński Paweł
Published: July 2021

The use of high voltage power cables in distribution and transmission networks is still increasing. As a result, the research on the electrical performance of cable lines is still up to date. In the paper, an analytical method of determining the power losses and the temperature distribution in the medium voltage cable was proposed. The main feature of the method is direct including the skin and proximity effects. Then the Joule law is used to express the power losses in the conductor and screen, and the Fourier-Kirchhoff equation is applied to find out the temperature distribution in the cable. The research was focused on a cable with isolated screen and return current in the screen taken into account. The proposed method was tested by using the commercial COMSOL software(5.6/COMSOL AB, Stockholm, Sweden) as well as by carrying out laboratory measurements. Furthermore, the results obtained via the proposed method were compared with those given in literature. The differences between the temperature values calculated by the analytical method, numerical computations and obtained experimentally do not exceed 10%. The proposed analytical method is suitable in prediction the temperature of the power cables with good accuracy.
Enhancing PV Self-Consumption through Energy Communities in Heating-Dominated Climates
Authors: Franzoi Nicola , Prada Alessandro , Verones Sara , Baggio Paolo
Published: July 2021

The European Union, in accordance with its decarbonization objectives, has enacted the Directive (EU) 2018/2001 and subsequently the Directive (EU) 2019/944 that legally recognizes and regulates the formation of citizen energy communities. These are believed to be key enablers for reducing buildings’ carbon footprint by allowing for a wider diffusion of on-site renewable energy generation and by maximizing renewable energy self-consumption. In this study, the benefits of the energy community are assessed through simulations of average Italian buildings of various sizes, different energy efficiency levels, equipped with a photovoltaic system and a heat pump-driven heating system, and located in heating-dominated climates. The work focuses on energy communities both at the apartment scale—i.e., in a multi-family building—and at the building scale—i.e., in a neighborhood. The net energy consumption, the self-consumption, and the self-sufficiency of all the possible energy communities obtainable by combining the different buildings are compared to the baseline case that is represented by the absence of energy sharing between independent building units. The energy community alone at both the building-scale and the neighborhood-scale increases self-consumption by up to 5% and reduces net energy consumption by up to 10%. However, when the energy community is combined with other maximization strategies such as demand-side management and rule-based control, self-consumption can be raised by 15%. These results quantify the lower bound of the achievable self-consumption in energy communities, which, in the rush towards climate neutrality, and in light of these results, could be considered among the solutions for rationalizing the energy consumption of buildings.
Energy Parameters of Miscanthus Biomass Pellets Supplemented with Copra Meal in Terms of Energy Consumption during the Pressure Agglomeration Process
Authors: Szyszlak-Bargłowicz Joanna , Słowik Tomasz , Zając Grzegorz , Blicharz-Kania Agata , Zdybel Beata , Andrejko Dariusz , Obidziński Sławomir
Published: July 2021

The process of pelleting miscanthus biomass often encounters issues related to the low durability of the obtained pellets and high energy inputs. To solve these issues, the use of copra meal as a supplement is proposed. This paper presents the results of research on energy parameters of miscanthus biomass pellets supplemented with copra meal in terms of energy consumption in the pressure agglomeration process. As part of this research, the energy parameters of miscanthus biomass, copra meal biomass, and their blends were characterized. Next, the raw materials were used for the production of pellets in the pressure agglomeration process. The investigations included proximate and ultimate analysis and estimation of heating values. Moreover, the total fat content, mechanical durability, kinetic strength, and bulk density were determined, and the energy consumption in the pelleting process was assessed. The results indicate that the energy consumption in the miscanthus biomass pelleting process can be substantially reduced by adding copra meal as a biocomponent. When the copra meal addition did not exceed 30%, the pellets exhibited over 95% durability, over 1200 kg∙m−3 density, and over 417 kg∙m−3 bulk density. Given the 44% reduction in energy consumption in the pellet production process and the energy efficiency of 4815 Wh·kg−1 determined in this study, copra meal may be an interesting material for use as an additive in the production of miscanthus biomass pellets.
Reliability of ERA5 Reanalysis Data for Wind Resource Assessment: A Comparison against Tall Towers
Authors: Gualtieri Giovanni
Published: July 2021

The reliability of ERA5 reanalyses for directly predicting wind resources and energy production has been assessed against observations from six tall towers installed over very heterogeneous sites around the world. Scores were acceptable at the FINO3 (Germany) offshore platform for both wind speed (bias within 1%, r = 0.95−0.96) and capacity factor (CF, at worst biased by 6.70%) and at the flat and sea-level site of Cabauw (Netherlands) for both wind speed (bias within 7%, r = 0.93−0.94) and CF (bias within 6.82%). Conversely, due to the ERA5 limited resolution (~31 km), large under-predictions were found at the Boulder (US) and Ghoroghchi (Iran) mountain sites, and large over-predictions were found at the Wallaby Creek (Australia) forested site. Therefore, using ERA5 in place of higher-resolution regional reanalysis products or numerical weather prediction models should be avoided when addressing sites with high variation of topography and, in particular, land use. ERA5 scores at the Humansdorp (South Africa) coastal location were generally acceptable, at least for wind speed (bias of 14%, r = 0.84) if not for CF (biased by 20.84%). However, due to the inherent sea–land discontinuity resulting in large differences in both surface roughness and solar irradiation (and thus stability conditions), a particular caution should be paid when applying ERA5 over coastal locations.
Thermal Insulation of Excavations and Its Effect on Climate Conditions
Authors: Szlązak Nikodem , Obracaj Dariusz , Swolkień Justyna
Published: July 2021

The article compares the climate conditions in an excavation with thermally insulated roof and sidewalls to the conditions when such insulation is absent. The analysis of the temperatures presented in the article consisted of limiting the heat transfer from the rock mass to the heading in one of the Polish coal mines. It is widely believed that the thermal insulation of heading sidewalls, through which fresh air is supplied, can substantially improve climate conditions. The article’s objective is to evaluate the impact of thermal insulation on the surface of the roof and sidewalls on the reduction in heat transfer from the strata with a high virgin temperature to mine air. Preventing the existing climate hazard involves higher costs of coal extraction, whereas the consequences of inadequate prevention threaten the health or life of the miners.
Optimizing Large-Scale Solar Field Efficiency: Latvia Case Study
Authors: Polikarpova Ilze , Kakis Roberts , Pakere Ieva , Blumberga Dagnija
Published: July 2021

Solar energy transformation technologies are increasingly being used worldwide in the district heating sector. In the Baltic states, only one district heating company has implemented a large-scale solar collector field into its thermal energy production system, which is analyzed within this research. In this study, we analyzed the first year operation of the solar field, solar collector efficiency, and several influencing factors, i.e., ambient air temperature, heat carrier flow, and the temperature difference between the supply and return heat carrier temperatures. The study includes collecting and compilation of the data, analyzing influencing factors, and data analysis using the statistical analysis method. In addition, the research presents a simplified multi-regression model based on the actual performance of a large-scale solar field, which allows for forecasting the efficiency of solar collectors by taking into account the main operational parameters of the DH system. The results show that solar energy covers around 90% of the summer heat load of a particular district heating system. However, they also show room for improvements in producing all the necessary heat in the summer using solar energy. The regression analyses show that the most significant correlation between all parameters examined was obtained in May, reaching R2 = 0.9346 in solar field efficiency evaluation. This is due to several suitable conditions for solar energy production, i.e., placing solar collectors at an angle for them to be the most productive, having enough space in the storage tank, and the demand for thermal energy being still higher than in the summer months.
Investigation of an Interior Micro Permanent Magnet Synchronous Motor
Authors: Pang Da-Chen , Shi Zhen-Jia , Chang Young-Ho , Huang Hua-Chih , Bui Gia-Thinh
Published: July 2021

This study describes the development of the world’s smallest interior permanent magnet synchronous motor (IPMSM) to increase the torque density of micromotors. The research evaluates the feasibility of the miniaturization of IPMSM since recent studies in this area focus on medium to large size compressor and traction motor applications. The standard-type and spoke-type IPMSM were selected for ease of micro machining. In order to surpass the performance of an inset motor of the same size used in previous research, the interior motors were designed with a different slot pole number, permanent magnet shape and rotor structure. Two types of interior motors were manufactured and tested to compare their performance. It was shown that the spoke-type interior motor had a better output torque, while the standard-type interior motor had a lower torque ripple, and both motors matched the specifications of commercially available motors. To achieve a higher torque density, the IPMSM designs increased the slot pole number from 6 slots 4 poles to 9 slots 6 poles. The torque density of the spoke-type motor was increased by 48% compared to the inset motor. The disadvantage is that the new design has a greater number of parts and smaller size, resulting in difficulties in manufacturing and assembly.
Technical Indicators for the Comparison of Power Network Development in Scenario Evaluations
Authors: Dicorato Maria , Tricarico Gioacchino , Forte Giuseppe , Marasciuolo Francesca
Published: July 2021

The problem of electric network expansion has different implications concerning the definition of criteria for the comparison of different candidate projects. Transmission expansion planning usually involves a set of economic and technical influences on market framework and on network operation over defined scenario evolutions, or even combining generation and transmission planning, although the application to real-sized networks usually implies cost-benefit analysis. In this paper, a methodology for performance analysis of a set of network development projects is proposed, including zonal market framework and load flow analysis, in order to individuate possible candidate projects and their influence on active power losses, admissible load increase and admissible renewable generation increase. Those merit indicators are compared among candidate projects by means of Analytic Hierarchy Process (AHP) method, aiming at determining the most promising solution under different weights of criteria. Moreover, the influence of network development investment cost on project selection is assessed by means of an extension of AHP. The procedure is applied to yearly operation of NREL-118 test system.
Economic and Environmental Assessment on Implementing Solar Renewable Energy Systems in Spanish Residential Homes
Authors: Cerezo-Narváez Alberto , Bastante-Ceca María-José , Piñero-Vilela José-María
Published: July 2021

In Europe, buildings are responsible for more than one third of the total final energy demands and greenhouse gas emissions. In the last twenty years, the European Union has published a succession of energy performance of building directives to define and ensure the fulfilment of a series of objectives regarding greenhouse gas emissions, energy consumption, energy efficiency and energy generation from renewable sources in buildings. For its part, Spain is adapting its legal framework, transposing these directives with the aim of achieving greater energy efficiency and sustainability for buildings. Under this context, an energy, economic and environmental assessment is performed to analyze the impact of these regulatory changes on a single-family home including a photovoltaic installation for self-consumption with surpluses and/or a solar thermal installation for domestic hot water supply, located in each one of the eight thousand one hundred thirty-one municipalities that make up Spain. The energy behavior of the original house is compared with that obtained after it is updated with these new facilities. The transient system simulation tool is used for the energy study. The results show that the European objectives are far exceeded. The energy savings achieved range from 67% to 126%, carbon dioxide emissions decrease by 42% to 100% and energy bills are reduced in cost by 32% to 81%. The findings of this work can be used by policymakers as guidelines for the development of national strategic plans and financial incentives for the promotion of small-scale residential photovoltaic and solar thermal applications, as well as by designers, supervisors, managers and developers to include them in their projects.
Design of a Low-Cost Multiplexer for the Study of the Impact of Soiling on PV Panel Performance
Authors: López Gabriel , Ramírez Diego , Alonso-Montesinos Joaquín , Sarmiento Juan , Polo Jesús , Martín-Chivelet Nuria , Marzo Aitor , Batlles Francisco Javier , Ferrada Pablo
Published: July 2021

Atmospheric factors, such as clouds, wind, dust, or aerosols, play an important role in the power generation of photovoltaic (PV) plants. Among these factors, soiling has been revealed as one of the most relevant causes diminishing the PV yield, mainly in arid zones or deserts. The effect of soiling on the PV performance can be analyzed by means of I–V curves measured simultaneously on two PV panels: one soiled and the other clean. To this end, two I–V tracers, or one I–V tracer along with a multiplexer, are needed. Unfortunately, these options are usually expensive, and only one I–V tracer is typically available at the site of interest. In this work, the design of a low-cost multiplexer is described. The multiplexer is controlled by a low-cost single-board microcontroller manufactured by ArduinoTM, and is capable of managing several pairs of PV panels almost simultaneously. The multiplexer can be installed outdoors, in contrast to many commercial I–V tracers or multiplexers. This advantage allows the soiling effect to be monitored on two PV panels, by means of I–V indoor tracers. I–V curves measured by the low-cost multiplexer are also presented, and preliminary results are analyzed.
Heterogeneous Impacts of Extreme Climate Risks on Global Energy Consumption Transition: An International Comparative Study
Authors: Peng Jiaying , Zheng Yuhang , Mao Ke
Published: July 2021

In response to the uncertainty of extreme climate change, energy consumption structure has been actively adjusted globally. Based on panel data of 101 countries or regions from 2006 to 2019, a panel data model with fixed effects is used to analyze the heterogeneous impacts of extreme climate risks on global consumption transition. The results show that extreme climate change has promoted the transition of the energy structure, reduced the consumption of fossil energy, and increased the consumption of renewable energy. Meanwhile, there are heterogeneous impacts of extreme climate change risks on the energy transition when different countries suffering from extreme weather conditions. Areas with high levels of economic development and coastal countries are more inclined to respond to climate change through energy transition. It is further confirmed that, under the impact of business cycle and oil price fluctuations, economic recession and falling oil prices will strengthen the correlation between climate risk and the global energy transition, and governments need to pay more attention to the impact of climate risks.
Computational Analysis of Premixed Syngas/Air Combustion in Micro-channels: Impacts of Flow Rate and Fuel Composition
Authors: Pokharel Sunita , Ayoobi Mohsen , Akkerman V’yacheslav
Published: July 2021

Due to increasing demand for clean and green energy, a need exists for fuels with low emissions, such as synthetic gas (syngas), which exhibits excellent combustion properties and has demonstrated promise in low-emission energy production, especially at microscales. However, due to complicated flame properties in microscale systems, it is of utmost importance to describe syngas combustion and comprehend its properties with respect to its boundary and inlet conditions, and its geometric characteristics. The present work studied premixed syngas combustion in a two-dimensional channel, with a length of 20 mm and a half-width of 1 mm, using computational approaches. Specifically, a fixed temperature gradient was imposed at the upper wall, from 300 K at the inlet to 1500 K at the outlet, to preheat the mixture, accounting for the conjugate heat transfer through the walls. The detailed chemistry of the ignition process was imitated using the San Diego mechanism involving 46 species and 235 reactions. For the given boundary conditions, stoichiometric premixed syngas containing various compositions of carbon monoxide, methane, and hydrogen, over a range of inlet velocities, was simulated, and various combustion phenomena, such as ignition, flame stabilization, and flames with repeated extinction and ignition (FREI), were analyzed using different metrics. The flame stability and the ignition time were found to correlate with the inlet velocity for a given syngas mixture composition. Similarly, for a given inlet velocity, the correlation of the flame properties with respect to the syngas composition was further scrutinized.
Fear of the COVID-19 Pandemic and Social Distancing as Factors Determining the Change in Consumer Payment Behavior at Retail and Service Outlets
Authors: Huterska Agnieszka , Piotrowska Anna Iwona , Szalacha-Jarmużek Joanna
Published: July 2021

The aim of this study was to identify the factors inducing customers to choose cashless payments made with payment cards at retail and service outlets during the COVID-19 pandemic. We identified factors that are crucial for consumers’ functioning under pandemic conditions, but which have so far been neglected in research. The estimated logit model indicates that the variables significantly influencing the more frequent choice of payment cards at retail outlets are related to the fear of infection and perception of the advantages of new technological solutions in connection with social distancing. Our study shows that, in addition to sociodemographic characteristics such as age and level of education, emotionally motivated factors induced by the pandemic have begun to play an important role in the transition to cashless payment.
Evaluation of Discoloration and Subterranean Termite Resistance of Four Furfurylated Tropical Wood Species after One-Year Outdoor Exposure
Authors: Hadi Yusuf Sudo , Nawawi Deded Sarip , Abdillah Imam Busyra , Pari Gustan , Pari Rohmah
Published: July 2021

The discoloration and resistance to subterranean termite attack of four furfurylated fast-growing tropical wood species were evaluated after outdoor exposure for 1 year in Bogor, Indonesia. For comparison purposes, imidacloprid-preserved and untreated wood samples were also prepared. Discoloration of all treated samples was measured before and after the furfurylation process. The wood specimens were then placed vertically to three-fourths of their length in the ground for 1 year, at which point they were evaluated for resistance to subterranean termite attack. After furfurylation, wood samples were darker in color than untreated wood, while imidacloprid-preserved wood was lighter. After 1-year exposure, furfurylated wood samples appeared to have the highest resistance to subterranean termite attack. These samples had minimal weight loss, indicating a substantial protection level. Imidacloprid-preserved wood had less resistance to termite attack, but was more resistant than untreated wood.
Availability and Structure of Coarse Woody Debris in Hemiboreal Mature to Old-Growth Aspen Stands and Its Implications for Forest Carbon Pool
Authors: Šēnhofa Silva , Šņepsts Guntars , Bičkovskis Kārlis , Jaunslaviete Ieva , Liepa Līga , Straupe Inga , Jansons Āris
Published: July 2021

European aspen deadwood is extensively studied as a habitat for saproxylic species, while less is known of its dynamics and role in carbon sequestration. We studied unmanaged mature (41–60 years), moderately overmature (61–80 years), overmature (81–100 years), and old-growth (101–140 years) and managed mature and moderately overmature aspen stands on fertile mineral soils. In unmanaged stands, marginal mean CWD volume was from 67.3 ± 12.1 m3 ha−1 in moderately overmature to 92.4 ± 5.1 m3 ha−1 in old-growth stands, with corresponding marginal mean CWD carbon pool 8.2 ± 1.6 t ha−1 and 12.5 ± 0.7 t ha−1 (all p > 0.05), respectively. High CWD volume was present in most stands, by at least two-thirds of plots comprising more than 20 m3 ha−1, and about half of CWD was larger than 30 cm in diameter. Changes in CWD species composition toward a higher proportion of deciduous deadwood in old-growth stands, together with a high volume of recently dead trees, suggest early senescence of the dominant aspen cohort.
Government Policy for the Procurement of Food from Local Family Farming in Brazilian Public Institutions
Authors: Soares Panmela , Martinelli Suellen Secchi , Davó-Blanes Mari Carmen , Fabri Rafaela Karen , Clemente-Gómez Vicente , Cavalli Suzi Barletto
Published: July 2021

This study aims to explore and compare Brazilian public institutional food services’ characteristics concerning the implementation of the government policy for the procurement of food from family farming (FF) and the opinions of food service managers on the benefits and difficulties of its implementation. We conducted a cross-sectional study employing an online questionnaire. The results were stratified by purchase. The Chi-square and Fisher’s Exact tests were applied. Five hundred forty-one food services’ managers participated in the study. Most claimed to buy food from FF, and this acquisition was more frequent among those working in institutions of municipalities <50,000 inhabitants, and educational and self-managed institutions. Those buying from FF developed more actions to promote healthy and sustainable food. Most recognized that the purchase could boost local farming and the economy and improve the institution’s food. However, the managers believe that the productive capacity of FF, the lack of technical assistance to farmers, production seasonality, and the bureaucratic procurement process hinder this type of purchase. The self-management of food services and the small size of the municipality might be associated with implementing the direct purchase policy from FF, which can contribute to building healthier and more sustainable food systems. However, the lack of public management support and the weak productive fabric may pose an obstacle to its maintenance or dissemination. The strengthening and consolidation of these policies require more significant government investments in productive infrastructure for family farming.