bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-World Safety and Effectiveness of Remdesivir and Corticosteroids in Hospitalized Patients with COVID-19
Authors: Caffrey Aisling R. , Liao J. Xin , Lopes Vrishali V. , LaPlante Kerry L. , Appaneal Haley J.
Published: February 2023

Real-world effectiveness studies of remdesivir in hospitalized patients with COVID-19 conducted to date have produced conflicting findings which may be due, in part, to treatment heterogeneity within standard of care comparison groups. Our objective was to evaluate the comparative effectiveness and safety of remdesivir in a cohort of patients all treated with corticosteroids. We conducted a retrospective cohort study in the National Veterans Affairs Healthcare System. We included hospitalized patients (>18 years old) with positive COVID-19 PCR tests and COVID-19 diagnosis codes, and corticosteroid treatment within 2 days of admission, from 1 May 2020 to 30 November 2021. Time-to-event outcomes included time to inpatient mortality (primary), discharge, mortality after discharge, readmission, and acute kidney injury and bacterial infection after treatment initiation. Propensity score (PS)-adjusted, PS-matched, and inverse probability of treatment weighted (IPTW) Cox proportional hazards regression models controlled for study timeframe, supplemental oxygen, vaccination status, and other important confounders. We observed significantly lower inpatient mortality, 90-day post-discharge mortality, 30-day post-discharge readmission, and significantly longer hospital stays in the remdesivir group (n = 14,509) compared with the non-remdesivir group (n = 4365). Higher rates of bacterial infections were observed in the remdesivir group. Acute kidney injury was lower in subgroup analyses restricting the study population to index dates in 2021, on supplemental oxygen, and fully vaccinated, and higher in those without baseline supplemental oxygen. When comparing the effectiveness and safety of remdesivir plus corticosteroids to a homogenous comparison group, all also treated with corticosteroids, mortality and readmission were significantly lower in the remdesivir group. Longer length of stay corresponds with duration of remdesivir treatment and may impact the risk of developing infections during the hospitalization, which requires further study.
Vaccine Breakthrough COVID-19 Outbreak in Section of a Hospital with 88% Attack Rate: Lessons to Be Learned
Authors: Ehelepola N. D. B. , Wijewardana B. A. S.
Published: February 2023

Vaccine breakthrough COVID-19 clusters with high attack rates are very rare. They paralyze affected section/s of the institution; thus, awareness of them is important. This is an analysis of a vaccine breakthrough COVID-19 cluster with an 88% attack rate involving 35 security guards (SGs) of the Teaching Hospital-Peradeniya, Sri Lanka. The identification of the particular combination of factors that resulted in this outbreak’s 88% attack rate was our main objective, because this knowledge is useful to prevent similar clusters of COVID-19 and other similar infections. We traced and documented contact details, risky behaviors, and medical history of all SGs. Contacts of all COVID-19 cases were tested for COVID-19. We created an epi-curve and identified the index case (IC). The epi-curve pattern indicates a propagated source outbreak. No SG was seriously immunocompromised. There was no breach in the local cold chain. The following combination of factors synergistically created this outbreak: communal meals at cramped spaces, unfamiliarity with vaccine breakthrough cases, disregard of the risk of infection from fully vaccinated coworkers, hesitancy to report COVID-19-like symptoms early on, symptomatic treatment of COVID-19-like patients without testing for COVID-19, permission to return home, and the Alpha variant of the SARS-CoV-2 virus.
Spatial Self-Phase Modulation in Graphene-Oxide Monolayer
Authors: Neupane Tikaram , Tabibi Bagher , Kim Wan-Joong , Seo Felix Jaetae
Published: February 2023

The spatial self-phase modulation (SSPM) of the optical field revealed the magnitude and polarity of nonlinear refraction coefficients of the graphene-oxide (GO) atomic layers in an aqueous base solution with a resonant excitation using a chopped quasi-static laser at 532 nm. The SSPM of the optical field as a result of the intrinsic nonlinear refraction coefficient of GO atomic layers and the spatial distribution of intensity displayed the concentric diffraction rings at the far field due to the coherent superposition of transverse wave vectors. The number of concentric rings as a function of the applied intensity revealed the nonlinear refraction coefficient of GO which was estimated to be ~–6.65 × 10−12 m2/W for the laser-excitation duration of ~0.32 s, where the negative polarity of nonlinear refraction coefficient was confirmed with the interference image profile of SSPM. The upper and vertical distortion of concentric rings at the far field at the longer laser-excitation duration of ~0.8 s indicates the distortion of the coherent superposition of transverse wave vectors due to the localized thermal vortex of GO in the aqueous solution that offers novel platforms of thermal metrology based on localized optical nonlinearity and temperature-sensitive all-optical switching.
Characterizations on Precipitations in the Cu-Rich Corner of Cu-Ni-Al Ternary Phase Diagram
Authors: Zhou Yongxin , Zheng Chenyang , Chen Jiankun , Chen Amin , Jia Lei , Xie Hui , Lu Zhenlin
Published: February 2023

Three kinds of Cu-Ni-Al alloys, whose chemical compositions are located in the Cu-rich corner of the isothermal section of the Cu-Ni-Al ternary phase diagram, were prepared by melting and casting firstly, and then solution and aging treatments were carried out. The microstructure was characterized and the competitive formation process of Ni-Al intermetallics were discussed. The results show that there are little amounts of NiAl phase at the grain boundary and needle- or particle-like Ni3Al phase inside the Cu matrix in all the as-cast alloys, although they are in the single-phase area. Solution and aging treatments mainly result in the disappearance and precipitation of Ni3Al phase, but the precipitations during aging are much smaller than those in the as-cast alloys. Thermodynamics and kinetics calculation indicate that the NiAl intermetallic wins out in the solidification process because of its lower change in Gibbs free energy, while Ni3Al phase is first to precipitate during aging due to its lower formation enthalpy and required Al concentration. The most important contribution of this work is that it proves that intermetallics can precipitate from the so-called single-phase zone in the Cu-rich corner of the Cu-Ni-Al phase diagram, which is the necessary prerequisite for the realization of high strength and high electrical conductivity.
Assessing Strain Rate Sensitivity of Nanotwinned Al–Zr Alloys through Nanoindentation
Authors: Richter Nicholas Allen , Sheng Xuanyu , Yang Bo , Stegman Benjamin Thomas , Wang Haiyan , Zhang Xinghang
Published: February 2023

Nanotwinned metals have exhibited many enhanced physical and mechanical properties. Twin boundaries have recently been introduced into sputtered Al alloys in spite of their high stacking fault energy. These twinned Al alloys possess unique microstructures composed of vertically aligned Σ3(112) incoherent twin boundaries (ITBs) and have demonstrated remarkable mechanical strengths and thermal stability. However, their strain rate sensitivity has not been fully assessed. A modified nanoindentation method has been employed here to accurately determine the strain rate sensitivity of nanotwinned Al–Zr alloys. The hardness of these alloys reaches 4.2 GPa while simultaneously exhibiting an improved strain rate sensitivity. The nanotwinned Al–Zr alloys have shown grain size-dependent strain rate sensitivity, consistent with previous findings in the literature. This work provides insight into a previously unstudied aspect of nanotwinned Al alloys.
Saudi Consensus Recommendations on the Management of Multiple Sclerosis: Symptom Management and Vaccination
Authors: Al Thubaiti Ibtisam A. , AlKhawajah Mona M. , Al Fugham Norah , Alissa Dema A. , Al-Jedai Ahmed H. , Al Malik Yaser M. , Almejally Mousa A. , Al-Mudaiheem Hajer Y. , Al-Omari Bedor A. , AlOtaibi Hessa S. , Al Yafeai Rumaiza H. , Babakkor Mohammed A. , Bunyan Reem F. , Cupler Edward J. , Hakami Mohammed , Kedah Hanaa M. , Makkawi Seraj , Saeed Leena H. , Saeedi Jameelah A. , Shosha Eslam , Al Jumah Mohammed A.
Published: February 2023

This article deals with recommendations on the management of symptoms of MS and on the provision of vaccinations in patients receiving disease-modifying therapies (DMTs). Symptoms of MS, such as fatigue, depression, urinary symptoms, spasticity, impairment of gait, and sexual dysfunction, are common in this population. Recognizing and addressing these symptoms is key to maintaining the quality of life of people with MS. Vaccination status should be reviewed and updated prior to initiation of DMTs. In general, vaccination should be avoided for variable periods after the initiation of some DMTs. Live attenuated vaccines are contraindicated and should be considered on a case-by-case basis. These consensus recommendations will present the best practices for vaccination in Saudi Arabia before, during, and after the COVID-19 pandemic. The recommendations will be updated periodically and as needed as new evidence becomes available.
Selection Bias in Real-World Data Studies Used to Support Health Technology Assessments: A Case Study in Metastatic Cancer
Authors: Jarada Tamer N. , O’Sullivan Dylan E. , Brenner Darren R. , Cheung Winson Y. , Boyne Devon J.
Published: February 2023

Real-world evidence has been increasingly used to support evaluations of emerging therapies. These investigations are often conducted in settings that may not be representative of the underlying population. The purpose of this investigation was to empirically quantify the magnitude of this selection bias. Individuals diagnosed with solid metastatic cancer in Alberta, Canada, between 2010–2019 were identified using the provincial cancer registry for 13 common metastatic sites. Two outcomes used to support oncology reimbursement decisions were examined: the proportion of individuals who initiated systemic therapy and median overall survival (OS). These outcomes were assessed in the entire population and in a subset of individuals who were referred to a medical oncologist. Among the 23,152 individuals in the entire population, 40.8% (95% CI: 40.2–41.4) initiated systemic therapy, and the median OS from diagnosis was 5.4 months (95% CI: 5.3–5.6). Among those who were referred to a medical oncologist (n = 13,372; 57.8%), 67.4% (95% CI: 66.6–68.2) initiated systemic therapy, and the median OS from diagnosis was 11.2 months (95% CI: 10.9–11.5). The magnitude of bias varied by cancer site where lower referral rates were associated with greater bias. Non-referral is an important source of selection bias in real-world investigations. Studies that rely on limited-catchment real-world data should be interpreted with caution, particularly in metastatic cancer settings.
Immunotherapy and Chemotherapy Versus Sleep Disturbances for NSCLC Patients
Authors: Zarogoulidis Paul , Petridis Dimitrios , Kosmidis Christoforos , Sapalidis Konstantinos , Nena Lila , Matthaios Dimitrios , Porpodis Konstantinos , Kakavelas Paschalis , Steiropoulos Paschalis
Published: February 2023

Introduction: Cancer patients are known to experience sleep disturbances that differ between disease stages and treatments. Regarding lung cancer patients and immunotherapy, information on their sleep disturbances has been recently acquired, but no comparison has been made between different treatment modalities. Patients and Methods: We recruited 98 non-small cell lung cancer patients; 49 had programmed death-ligand 1 expression of ≥50% and received immunotherapy as first-line treatment and 49 had programmed death-ligand 1 expression in the range from 0–49 and received chemotherapy as first-line treatment. All patients were stage IV, but with no bone metastasis. Sleep disturbances were recorded through polysomnography and sleep questionnaires. Results: For immunotherapy patients with PD-L1 expression ≥ 50%, the disease response was rapid and the sleep disturbances decreased rapidly. On the other hand, for chemotherapy patients, the sleep disturbances remained for all those patients that had partial response and stable disease. It was noticed that chemotherapy drugs induce severe adverse effects. Discussion: In our study, it was observed that patients with complete response had reduced sleep disturbances in the case of immunotherapy patients. However, sleep disturbances continued for several patients in the chemotherapy group due to the adverse effects of chemotherapy drugs. In conclusion: Immunotherapy drugs on their own do not induce sleep disturbances and, through treatment response, alleviate sleep disturbances in lung cancer patients.
Continuous Real-Time Neuropsychological Testing during Resection Phase in Left and Right Prefrontal Brain Tumors
Authors: Tomasino Barbara , Guarracino Ilaria , Ius Tamara , Skrap Miran
Published: February 2023

Background: Executive functions are multi-component and are based on large-scale brain networks. For patients undergoing brain surgery in the prefrontal cortex, resection in the anterior prefrontal sites is assisted by continuous monitoring of their performance on several tasks measuring components of executive functions. In this study, we did not test patients during direct cortical stimulation, but during resection itself. We chose tests routinely used to assess executive functions and included them in a protocol for left (LH) and right (RH) hemisphere prefrontal resections. This protocol is meant to be used during real-time neuropsychological testing (RTNT)—an already established monitoring technique. Methods: We retrospectively reviewed a consecutive series of 29 adult patients with glioma in the superior and middle frontal areas who performed the RTNT sequence throughout the resection phase. The testing protocol comprised 10 tests for LH frontal resections and 9 tests for RH frontal resections. Results: RH patients showed a median performance on RTNT with significantly lower scores for visuo-spatial attention and emotion processing (95% Confidence Interval Lower bound of 66.55 and 82.57, respectively, χ2 (7) = 32.8, p < 0.001). LH patients showed a median performance on RTNT, with significantly lower scores for selective attention and working memory (95% Confidence Interval Lower bound of 51.12, χ2 (5) = 20.31 p < 0.001) and minimum scores for the same task and for the Stroop test (χ2 (5) = 17.86, p < 0.005). The delta for accuracy between the first and the last RTNT run was not statistically significant (RH patients: χ2 (7) = 10.49, p > 0.05, n.s.; LH patients: χ2 (5) = 3.35, p > 0.05, n.s.). Mean extent of resection was 95.33% ± 9.72 for the RH group and 94.64% ± 6.74 for the LH group. Patients showed good performance post- vs. pre-surgery. The greater difference in the number of LH patients scoring within the normal range was found for the symbol-digit modality test (83.3% to 62%), Stroop test (100% to 77%) and short-term memory (84.61% to 72.72%) and working memory (92.3% to 63.63%). For RH patients, the main changes were observed on the clock drawing test (100% to 77.7%) and cognitive estimation (100% to 72.7%). Conclusions: Frontal RTNT offers continuous and reliable feedback on the patients’ cognitive status during resection in frontal areas.
Not the Last Piece of the Puzzle: Niphargus Phylogeny in Hungary
Authors: Balázs Gergely , Borko Špela , Angyal Dorottya , Zakšek Valerija , Biró Anna , Fišer Cene , Herczeg Gábor
Published: February 2023

The Palaearctic genus Niphargus is a promising model system to understand subterranean fauna genesis in Europe. The Pannonian Plain (mainly covered by Hungary) in Central Europe, once being the area of the Paratethys, is a key area for Niphargus diversification. However, our knowledge on Hungarian species of Niphargus is primarily based on sporadic taxonomical works from the pre-molecular era. Here, we studied 14 localities, covering the eight valid Hungarian species of Niphargus and including nine previously unstudied populations. Based on sequences of three gene fragments, we reconstructed their phylogeny using maximum likelihood and Bayesian approaches. We found that not all Hungarian species of Niphargus are closely related, and even species sampled at the same localities can belong to different clades. Some Hungarian species form monophyletic clades, while others are nested in various non-Hungarian lineages. The new populations are all genetically distinct from the known species. Our results suggest that the Hungarian Niphargus fauna has originated from seven unrelated clades and its diversity is underestimated due to unknown populations and cryptic species. The detection of genetically distinct species of Niphargus from non-carbonate regions calls for further research efforts. The high diversity and the number of putative new species in the N. tatrensis clade warrants further, high-resolution phylogenetic studies.
Testolactone: The Rise and Fall of a Drug
Authors: Savic Marina , Kuzminac Ivana , Nikolic Andrea
Published: February 2023

Testolactone is structurally related to testosterone and belongs to the first generation of aromatase inhibitors. It is a non-selective irreversible aromatase enzyme inhibitor that was one of the first steroids used in the clinical treatment of breast cancer. The use of testolactone in the treatment of breast cancer started in 1970, although its ability to inhibit aromatase was not discovered until 1975. Its use was primarily based on the inhibition of estrogen synthesis, which was applied in the treatment of estrogen-dependent breast cancers, in the treatment of disorders of sex steroid excess, familial male-limited precocious puberty, or in the treatment of patients with McCune–Albright syndrome, etc. The weak inhibitory activity of testolactone, and the moderate clinical response, prevented its widespread use, which ultimately resulted in withdrawal from the drug market in 2008. This review paper is dedicated to testolactone, its rise in the second half of the 20th century, and its fall in the first decade of the 21st century. Regardless of withdrawal from the market, for many years testolactone was a drug that improved the quality of life of patients facing one of the most serious diseases today, and for this reason, this paper describes medicinal application, synthesis, and modifications of testolactone.
Molten Salt Corrosion Behavior of Dual-Phase High Entropy Alloy for Concentrating Solar Power Systems
Authors: Patel Kunjal , Hasannaeimi Vahid , Sadeghilaridjani Maryam , Muskeri Saideep , Mahajan Chaitanya , Mukherjee Sundeep
Published: February 2023

Dual-phase high entropy alloys have recently attracted widespread attention as advanced structural materials due to their unique microstructure, excellent mechanical properties, and corrosion resistance. However, their molten salt corrosion behavior has not been reported, which is critical in evaluating their application merit in the areas of concentrating solar power and nuclear energy. Here, the molten salt corrosion behavior of AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) was evaluated in molten NaCl-KCl-MgCl2 salt at 450 °C and 650 °C in comparison to conventional duplex stainless steel 2205 (DS2205). The EHEA showed a significantly lower corrosion rate of ~1 mm/year at 450 °C compared to ~8 mm/year for DS2205. Similarly, EHEA showed a lower corrosion rate of ~9 mm/year at 650 °C compared to ~20 mm/year for DS2205. There was selective dissolution of the body-centered cubic phase in both the alloys, B2 in AlCoCrFeNi2.1 and α-Ferrite in DS2205. This was attributed to micro-galvanic coupling between the two phases in each alloy that was measured in terms of Volta potential difference using a scanning kelvin probe. Additionally, the work function increased with increasing temperature for AlCoCrFeNi2.1, indicating that the FCC-L12 phase acted as a barrier against further oxidation and protected the underlying BCC-B2 phase with enrichment of noble elements in the protective surface layer.
Emerging Trends of Electrochemical Sensors in Food Analysis
Authors: Marx Ítala M. G.
Published: February 2023

Food quality and safety pose an increasing threat to human health worldwide [...]
Catalysts for ORR Based on Silver-Modified Graphene Oxide and Carbon Nanotubes
Authors: Vinogradov Kirill Yurievich , Shafigulin Roman Vladimirovich , Tokranova Elena Olegovna , Vostrikov Sergey Vladimirovich , Martynenko Evgeniya Andreevna , Podlipnov Vladimir Vladimirovich , Kazakevich Pavel Vladimirovich , Sheldaisov-Meshcheryakov Artem Anatolevich , Vinogradov Nikolai Aleksandrovich , Bulanova Andzhela Vladimirovna
Published: February 2023

The main obstacle to the widespread dissemination of fuel cells is the high cost, so researchers are actively searching for ways to replace the expensive platinum catalyst with cheaper analogs. In this paper we studied the Ag- and Pd-containing carbon catalysts based on carbon nanotubes and graphene oxide. The study of the textural characteristics of the catalysts showed that the greatest specific surface area has a catalyst based on MWCNT containing 10% silver, all synthesized catalysts are mainly mesoporous, and the content of micropores is insignificant. Raman spectroscopy and SEM data indicate a significant change in the structure of the modified carriers compared to pure MWCNT and GO. An electrochemical experiment was performed and linear voltammetric diagrams were obtained and compared with the voltammetric diagrams obtained on the platinum catalyst. GO_Ag 10% and MWCNT_Ag 10% Pd 10% are closest in the values of kinetic parameters in both kinetic and diffusion regions. GO_Ag 10% has the highest initial potential Eonset = −0.145 V and MWCNT_Ag 10% Pd 10% has the highest half-wave potential E½ = −0.23 V. The studied catalysts have characteristics comparable to those presented in the literature.
Energy Consumption Analysis of the Selected Navigation Algorithms for Wheeled Mobile Robots
Authors: Rapalski Adam , Dudzik Sebastian
Published: February 2023

The article presents the research on navigation algorithms of a wheeled mobile robot with the use of a vision mapping system and the analysis of energy consumption of selected navigation algorithms, such as RRT and A-star. Obstacle maps were made with the use of an RGBW camera, and binary occupation maps were also made, which were used to determine the traffic path. To recreate the routes in hardware, a programmed Pure Pursuit controller was used. The results of navigation were compared on the basis of the forward kinematics model and odometry measurements. Quantities such as current, except (x, y, phi), and linear and angular velocities were measured in real time. As a result of the conducted research, it was found that the RRT star algorithm consumes the least energy to reach the designated target in the designated environment.
A New Explicit Sequentially Coupled Technique for Chemo-Thermo-Poromechanical Modelling and Simulation in Shale Formations
Authors: Akanji Lateef T. , Ibrahim Adamu , Hamidi Hossein , Matthai Stephan , Akisanya Alfred
Published: February 2023

A new explicit sequentially coupled technique for chemo-thermo-poromechanical problems in shale formations is developed. Simultaneously solving the flow and geomechanics equations in a single step is computationally expensive with consequent limitations on the computations involving well or reservoir-scale geometries. The newly developed solution sequence involves solving the temperature field within the porous system. This is followed by the computation of the chemical activity constrained by the previously computed temperature field. The pore pressure is then computed by coupling the pore thermal and chemical effects but without consideration of the volumetric strains. The geomechanical effect of the volumetric strain, stress tensors, and associated displacement vectors on the pore fluid is subsequently computed explicitly in a single-step post-processing operation. By increasing the borehole pressure to 20 MPa, it is observed that the rock displacement and velocities concurrently increase by 50%. However, increasing the wellbore temperature and chemical activities shows only a slight effect on the rock and pore fluid. In the chemo-thermo-poroelasticity steady-state simulation, the maximum displacements recorded in the Hmin and Hmax are 0.00633 m and 0.0035 m, respectively, for 2D and 0.21 for the 3D simulation. In the transient simulation, the displacement values are observed to increase gradually over time with a corresponding decrease in the maximum pore-fluid velocity. A comparison of this work and the partial two-way coupling scheme in a commercial simulator for the 2D test cases was carried out. The maximum differences between the computed temperatures, displacement values, and fluid velocities are 0.33%, 0.7%, and 0%, respectively. The analysed results, therefore, indicate that this technique is comparatively accurate and more computationally efficient than running a full or partial two-way coupling scheme.
Micro-Scale Lattice Boltzmann Simulation of Two-Phase CO2–Brine Flow in a Tighter REV Extracted from a Permeable Sandstone Core: Implications for CO2 Storage Efficiency
Authors: Wan Yidi , Jia Chengzao , Zhao Wen , Jiang Lin , Chen Zhuxin
Published: February 2023

Deep saline permeable sandstones have the potential to serve as sites for CO2 storage. However, unstable CO2 storage in pores can be costly and harmful to the environment. In this study, we used lattice Boltzmann (LB) simulations to investigate the factors that affect steady-state CO2–brine imbibition flow in sandstone pores, with a focus on improving CO2 storage efficiency in deep saline permeable sandstone aquifers. We extracted three representative element volumes (REVs) from a digital rock image of a sandstone core and selected a tighter REV in the upper subdomain so that its permeability would apparently be lower than that of the other two based on single-phase LB simulation for further analysis. The results of our steady-state LB simulations of CO2–brine imbibition processes in the tighter REV under four differential pressures showed that a threshold pressure gradient of around 0.5 MPa/m exists at a differential pressure of 200 Pa, and that higher differential pressures result in a greater and more linear pressure drop and stronger channelization after the flow are initiated. Furthermore, we conducted simulations over a range of target brine saturations in the tighter REV at the optimal differential pressure of 400 Pa. Our findings showed that the relative permeability of CO2 is greatly reduced as the capillary number falls below a certain threshold, while the viscosity ratio has a smaller but still significant effect on relative permeability and storage efficiency through the lubrication effect. Wettability has a limited effect on the storage efficiency, but it does impact the relative permeability within the initial saturation range when the capillary number is low and the curves have not yet converged. Overall, these results provide micro-scale insights into the factors that affect CO2 storage efficiency in sandstones.
Estimating the Error of Fault Location on Overhead Power Lines by Emergency State Parameters Using an Analytical Technique
Authors: Kulikov Aleksandr , Ilyushin Pavel , Suslov Konstantin , Filippov Sergey
Published: February 2023

Fault location on overhead power lines achieved with the highest possible accuracy can reduce the time to locate faults. This contributes to ensuring the stability of power systems, as well as the reliability of power supply to consumers. There are a number of known mathematical techniques based on different physical principles that are used in fault location on overhead power lines and whose errors vary. Fault location on overhead power lines uses techniques based on the estimation of emergency state parameters, which are referred to as distance-to-fault techniques and are widely used. They are employed in digital protection relay terminals and power-line fault locators. Factors that have a significant impact on the error of fault location on overhead power lines by emergency state parameters are design, manufacturing, and operation. The aim of this article is to analyze the existing techniques and to present a new analytical technique for estimating errors of fault location on overhead power lines by using emergency state parameters. The technique developed by the authors makes it possible to properly take into account a set of random factors, including various measurement errors of currents and voltages in the emergency state, which have a significant impact on the fault location on overhead power lines error. The technique allows one to determine more accurately the fault location and the size of the inspection area, which is necessary to reduce the time it takes to carry out emergency recovery operations. The proposed technique can be applied in fault locators and digital protection relay terminals that use both single-end, double- and multi-end sensing of currents and voltages in the emergency state.
Numerical Simulation Study of Huff-n-Puff Hydrocarbon Gas Injection Parameters for Enhanced Shale Oil Recovery
Authors: Garipova Alsu , Mukhina Elena , Cheremisin Alexander , Spivakova Margarita , Kasyanenko Anton , Cheremisin Alexey
Published: February 2023

Gas injection has already proven to be an efficient shale oil recovery method successfully tested all around the world. However, gas-enhanced oil recovery methods have never been implemented or tested for the greatest Siberian shale oil formation yet. This article proposes numerical simulation of a hydrocarbon gas injection process into a horizontal well with multiple hydraulic fractures perforating Bazhenov shale oil formation in Western Siberia characterized by ultra-low permeability. A complex field-scale numerical study of gas injection for such a formation has never been performed before and is presented for the first time in our work. The hydrodynamic compositional simulation was performed utilizing a commercial simulator. A sensitivity study for different operating parameters including cycle times, bottom-hole pressures for the production and injection period, and injected gas composition was performed after the model was history matched with the available production data. Some uncertain reservoir properties such as relative permeability curves were also sensitized upon. Two different ways of accounting for multiple hydraulic fractures in the simulation model are presented and the simulation results from both models are compared and discussed. Eventually, huff-n-puff injection of a hydrocarbon gas resulted in a 34–117% increase in oil recovery depending on the fracture model.
Prospect of Green Hydrogen Generation from Hybrid Renewable Energy Sources: A Review
Authors: Sarker Asim Kumar , Azad Abul Kalam , Rasul Mohammad G. , Doppalapudi Arun Teja
Published: February 2023

Hydrogen is one of the prospective clean energies that could potentially address two pressing areas of global concern, namely energy crises and environmental issues. Nowadays, fossil-based technologies are widely used to produce hydrogen and release higher greenhouse gas emissions during the process. Decarbonizing the planet has been one of the major goals in the recent decades. To achieve this goal, it is necessary to find clean, sustainable, and reliable hydrogen production technologies with low costs and zero emissions. Therefore, this study aims to analyse the hydrogen generation from solar and wind energy sources and observe broad prospects with hybrid renewable energy sources in producing green hydrogen. The study mainly focuses on the critical assessment of solar, wind, and hybrid-powered electrolysis technologies in producing hydrogen. Furthermore, the key challenges and opportunities associated with commercial-scale deployment are addressed. Finally, the potential applications and their scopes are discussed to analyse the important barriers to the overall commercial development of solar-wind-based hydrogen production systems. The study found that the production of hydrogen appears to be the best candidate to be employed for multiple purposes, blending the roles of fuel energy carrier and energy storage modality. Further studies are recommended to find technical and sustainable solutions to overcome the current issues that are identified in this study.
A Design and Validation of 400 W PV Emulator Using Simple Equivalent Circuit for PV Power System Test
Authors: Choi Seungho , Park Sangyoung , Hong Junhee , Won Jehyuk
Published: February 2023

In this paper, we propose a photovoltaic emulator (PVE) composed of a series of connected power diodes with a single constant current source, rather than a power converter-based PVE. Accordingly, this enables readily verifying the operation because a the simple hardware structure and lack of a complex control algorithm. The proposed PVE can be intuitively implemented using the proposed selection criteria for the power diode and equivalent resistances. Since there is no feedback control based on complex analog/digital controls and sensors, the control response can be very fast. In addition, the proposed PVE can be easily integrated with a PV power system such as a power optimizer, to allow testing in a simple and flexible manner. Spice simulation was performed based on the electrical characteristics provided by the solar panel manufacturer, and this was utilized to validate the applied emulator circuit model, the Norton Equivalent Circuit. During the design process, the simulation helped to manufacture the PVE within error ranges satisfying the desired I–V and P–V curves, as well as the maximum power point (MPP). Partial shading could be easily implemented through use of the multiple series connection of individual PVEs, demonstrating local MPP and global MPP. A 400 W class PVE was built through appropriate power diode selection, with a thermal design to increase the output power. Moreover, its performance and feasibility were verified through intensive experiments. The measured efficiency, transient response time, and maximum transient error of the partial shading tests were 91%, 22 μs, and 5.8%, respectively.
Mapping Seasonal Variability of Buildings Electricity Demand profiles in Mediterranean Small Islands
Authors: Ferrari Simone , Zagarella Federica , Caputo Paola , Beccali Marco
Published: February 2023

In communities with a high tourist influx and warm climate, such as Mediterranean small islands, the energy demands for space cooling and domestic hot water are expected to significantly increase during summer. Considering the current energy context, for succeeding energy transition and reducing the dependency on not endogenous fossil fuels, it is paramount to increase the deployment of renewable sources of energy, especially wind and solar which, however, are aleatory and unpredictable. Hence, to reduce the high costs for energy supply in these contexts, the analysis of the variation of energy consumption is fundamental. Moreover, mapping the spatial distribution of energy profiles can be useful to have an overview at a large scale of the considered building stock. Within this frame, a Geographic-Information-System-based procedure was implemented to estimate the residential buildings energy demand profiles, focusing on the seasonal variation. The adopted method can provide a valid supporting tool for decision makers that have to implement smart energy strategies in contexts with a high variation of the energy demand and evident electricity summer peaks. The method for mapping the energy demand profiles, implemented on the small island of Pantelleria, can be applied to other similar contexts, also supporting energy policies in the implementation of renewable energy communities.
Feasibility Study of the Grid-Connected Hybrid Energy System for Supplying Electricity to Support the Health and Education Sector in the Metropolitan Area
Authors: Ahmed Md. Rasel , Hasan Md. Rokib , Al Hasan Suharto , Aziz Muhammad , Hoque Md. Emdadul
Published: February 2023

One of the biggest issues impeding a country’s progress is the lack of power. To overcome this issue, hybrid renewable energy systems (HRES) play an important role. Due to rising consumption and diminishing resources globally, sustainability has recently attracted more attention. Bangladesh has access to renewable energy sources, including solar, micro-hydro, biomass, wind, and others. The objective of this research is to minimize the net present cost (NPC), cost of energy (COE), and CO2 emissions of the suggested electricity network using the Hybrid Optimization Model for Multiple Energy Resources (HOMER) Pro Software. This investigation explores the possible use of a hybridized energy system (i.e., solar, wind, and diesel) with battery storage in Bangladesh’s northern area. Utilizing HOMER Pro software, an optimal grid-connected system is chosen after evaluating the techno-economic viability of several configuration options. For the Rangpur metropolitan region, seven distinct grid-connected solutions with stationary renewable sources are simulated. The HRES is designed to meet demands for hospital, diagnostic, school, and operation theatre loads of 3250.00 kWh, 250.00 kW maximum requirement, and 570.00 kWh, 71.25 kW maximum electricity demand, respectively. Multivariate linear regression (MLR) is used to assess the suggested optimal combination in terms of system size, cost, technical performance, and environmental stability. The findings show that the metric real-time rate (annual) has emerged as the most advantageous option since economic criteria like total NPC and COE are preferred above others.
Analysis of Asymmetric Hybrid Modular Multilevel Topology for Medium-Voltage Front-End Converter Applications
Authors: Ali Muhammad , Farooq Ajmal , Khan Muhammad Qasim , Khan Muhammad Mansoor , Mihet-Popa Lucian
Published: February 2023

Modular multilevel converters (MMCs) have been conceived as an alternative in front-end converter applications to enhance the converter system’s reliability, minimize total harmonic distortion, and improve power quality. These converters utilize several DC-link capacitors and power electronic switches, along with switches operating with high switching frequencies, to attain the desired characteristics. Thereby, this paper systematically proposes a novel three-phase asymmetric hybrid modular multilevel converter (AHMMC) for front-end converters used in lower-medium-voltage applications. The AHMMC configuration is based on a three-phase converter connected to a per-phase series arrangement with a cascaded converter module (CCM). The study investigates the AHMMC and proposes a control scheme, which minimizes the voltage range on switches and maintains the current to its reference value. Furthermore, the study also introduces an active balancing of voltage across DC-link capacitors based on the phase opposition disposition PWM (POD-PWM) method. Our new configuration has features such as low switching loss, reduced DC-link voltage, a wider modulation range for the unity power factor (PF), and low voltage and current harmonic distortion. The simulation results are added to verify the performance of the new AHMMC topology and the usefulness of the modular control scheme. In addition, a low-voltage laboratory prototype based on customized control and power boards is built to validate the proposed converter and its control scheme in practice.
Evaluation of Methane Emissions in Daily Operations and Accidents: A Case Study of a Local Distribution Company in China
Authors: Xie Yitong , Qin Chaokui , Wu Cong , Zhang Lubing , Cao Ping
Published: February 2023

As the second-largest contributor to historical global warming, methane emissions must be controlled to slow down temperature increase and achieve climate benefits. Due to a lack of knowledge about the specific sources and processes, a quantitative approach will lead to inaccurate estimation. In this paper, a typical local distribution company with more than 100 years of operation history was chosen. Detailed procedures of pipeline constructions and accidents were investigated, and critical steps leading to methane emissions were clarified. Then emission quantification methodologies for all processes were proposed, including a new pipeline connection, new regulator connection, emergency repair and third-party damages. As a basis for emission estimation, the distribution of parameters, such as diameter, length and pressure, was counted. Then the emission rates of all projects were calculated, and emission factors were established. The average emission rates of the new pipeline connection, new regulator connection, emergency repair, third-party damage (medium pressure) and third-party damage (low pressure) were 234 kg, 147 kg, 217 kg, 17,282 kg and 62 kg, respectively. In addition, the total methane emission in China from these sources was estimated to be about 5 × 104 t, which is large enough to attract attention. The work in this paper aims to establish a reasonable framework to evaluate venting methane emissions from the distribution process of natural gas.
A Review of the Use of Electrolytic Cells for Energy and Environmental Applications
Authors: Ferreira Ana P. R. A. , Oliveira Raisa C. P. , Mateus Maria Margarida , Santos Diogo M. F.
Published: February 2023

There is a significant push to reduce carbon dioxide (CO2) emissions and develop low-cost fuels from renewable sources to replace fossil fuels in applications such as energy production. As a result, CO2 conversion has gained widespread attention as it can reduce the accumulation of CO2 in the atmosphere and produce fuels and valuable industrial chemicals, including carbon monoxide, alcohols, and hydrocarbons. At the same time, finding ways to store energy in batteries or energy carriers such as hydrogen (H2) is essential. Water electrolysis is a powerful technology for producing high-purity H2, with negligible emission of greenhouse gases, and compatibility with renewable energy sources. Additionally, the electrolysis of organic compounds, such as lignin, is a promising method for localised H2 production, as it requires lower cell voltages than conventional water electrolysis. Industrial wastewater can be employed in those organic electrolysis systems due to their high organic content, decreasing industrial pollution through wastewater disposal. Electrocoagulation, indirect electrochemical oxidation, anodic oxidation, and electro-Fenton are effective electrochemical methods for treating industrial wastewater. Furthermore, bioenergy technology possesses a remarkable potential for producing H2 and other value-added chemicals (e.g., methane, formic acid, hydrogen peroxide), along with wastewater treatment. This paper comprehensively reviews these approaches by analysing the literature in the period 2012–2022, pointing out the high potential of using electrolytic cells for energy and environmental applications.
Calculation of AC Losses in a 500 kJ/200 kW Multifilamentary MgB2 SMES Coil
Authors: Morandi Antonio , Fabbri Massimo , Ribani Pier Luigi , Lo Franco Francesco , Mandrioli Riccardo , Melaccio Umberto , Magrassi Daniele , Neri Martina , Capelluto Alessio , Tropeano Matteo , Gandolfi Chiara
Published: February 2023

SMES technology based on MgB2 superconductor and cryogenic-free cooling can offer a viable solution to power-intensive storage in the short term. One of the main obstacles to the development of dry-cooled SMES systems is the heat load removal due to the AC loss of the superconductor during fast charging and discharging cycles at high power. Accurate knowledge of the amount and distribution of AC loss in the coil is of paramount importance for the sizing and the design of the cooling system and for assessing the possible operational limits of the technology. In this manuscript, the AC loss of a 500 kJ/200 kW multifilamentary MgB2 SMES during charge–discharge cycling at full power is numerically investigated. The methodology and assumptions of the calculation are briefly resumed, and numerical results are reported and discussed in detail. In particular, the time profile and the distribution of the dissipated power all over the coil are reported. An average dissipation of 85.5 mW/m is found all over the coil during one charge–discharge cycle at full power, with a peak of 150.1 mW/m in the turns lying at the ends of the coil.
A New Two-Foci V-Trough Concentrator for Small-Scale Linear Fresnel Reflectors
Authors: Pardellas Alberto , Fortuny Ayuso Pedro , Bayón Luis , Barbón Arsenio
Published: February 2023

We present the design of an original secondary cavity for use in Small-Scale Fresnel Reflectors in photovoltaic applications. The cavity is similar to the classical V-trough, but the primary reflector system is configured so that there are two focal points on the aperture. The rays coming from each side of the primary system reach the opposite side of the cavity, producing a non-symmetrical distribution of the irradiance. This modifies the acceptance half-angle and allows us to break the maximum limit for the concentration ratio of ideal symmetric concentrators. Our study is analytic, and we provide formulas for any number of reflections. Numerical simulations with a ray-tracing program based on MATLAB are included. We provide a comparison of optical concentration ratio, height and cost parameter between our system and two classical designs with a single focal point: the V-trough and the Compound Parabolic concentrators. This way, we verify that our design yields better concentration ratios while keeping the ray acceptance rate at one. Our solution proves to be better than both the classical one-focus V-trough and the Compound Parabolic concentrator. Specifically, the proposed solution is significantly better than the classical one-focus V-trough in optical concentration ratio, with an increase between 15.02 and 35.95%. As regards the compound parabolic concentrator, the optical concentration ratio is always slightly better (around 4%). The height of the cavity, however, is notably less in this design (around 54.33%).
Guest Editorial: Special Issue of ESREL2020 PSAM15
Authors: Baraldi Piero , Razavi-Far Roozbeh , Zio Enrico
Published: February 2023

This Special Issue includes seven extended works that have been selected from papers presented at the ESREL 2020 PSAM 15 Conference, the 30th European Safety and Reliability Conference (ESREL 2020) and the 15th Probabilistic Safety Assessment and Management Conference (PSAM 15), jointly held virtually on 1–5 November 2020 to discuss the second wave of the pandemic breakout [...]