bluuebunny/crossref_metadata_2025 huggingface dataset:
18F-Fluorodeoxyglucose Positron Emission Tomography Is Useful in the Evaluation of Prognosis in Retroperitoneal Sarcoma
Authors: Wakamatsu Toru , Imura Yoshinori , Tamiya Hironari , Yagi Toshinari , Yasuda Naohiro , Nakai Sho , Nakai Takaaki , Outani Hidetatsu , Hamada Kenichiro , Kakunaga Shigeki , Araki Nobuhito , Ueda Takafumi , Takenaka Satoshi
Published: September 2021

Background: Retroperitoneal sarcomas are rare neoplasms that occur in the retroperitoneum. Complete surgical resection is the only effective treatment option. The prediction of prognosis by histological diagnosis has not yet been established. The purpose of this study was to identify the usefulness of [18-F] fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging for validating the prognosis of retroperitoneal sarcoma (RPS) established by histological diagnosis. Methods: We retrospectively reviewed 201 patients with RPS treated at the Osaka International Cancer Institute between 2010 and 2021. We extracted the clinical data, including standardized uptake values (SUVs), evaluated with FDG-PET, and statistically analyzed the data. Results: The median age of patients was 64 years (range, 31–85 years). A total of 101 (50.2%) patients were men, and 100 (49.8%) were women. Surgical resection was performed in 155 (77.1%) patients. On histological analysis, 75 (37.3%), 52 (25.9%), and 29 (14.4%) patients were diagnosed with dedifferentiated liposarcoma, well-differentiated liposarcoma, and leiomyosarcoma, respectively. The median survival time for patients with high maximum SUV (SUVmax) (≥4) or low SUVmax (<4) was 275.8 months and 79.5 months, respectively. Furthermore, among the patients with dedifferentiated liposarcoma, the overall survival rate for patients with high SUVmax (≥4) was significantly lower than that of those with low SUVmax (<4). Conclusions: The present study demonstrated that SUVmax calculated with FDG-PET was useful as a prognostic factor in RPS, especially in dedifferentiated liposarcoma and Grade2 RPS. To devise a treatment strategy for RPS, SUVmax during FDG-PET scan may be considered for clinical assessment.
Transcription Factor Homeobox D9 Drives the Malignant Phenotype of HPV18-Positive Cervical Cancer Cells via Binding to the Viral Early Promoter
Authors: Hayashi Shigenori , Iwata Takashi , Imagawa Ryotaro , Sugawara Masaki , Chen Guanliang , Tanimoto Satoko , Sugawara Yo , Tanaka Ikumo , Matsui Tomoya , Nishio Hiroshi , Nakamura Masaru , Katoh Yuki , Mori Seiichiro , Kukimoto Iwao , Aoki Daisuke
Published: September 2021

Persistent infections with two types of human papillomaviruses (HPV), HPV16 and HPV18, are the most common cause of cervical cancer (CC). Two viral early genes, E6 and E7, are associated with tumor development, and expressions of E6 and E7 are primarily regulated by a single viral promoter: P97 in HPV16 and P105 in HPV18. We previously demonstrated that the homeobox D9 (HOXD9) transcription factor is responsible for the malignancy of HPV16-positive CC cell lines via binding to the P97 promoter. Here, we investigated whether HOXD9 is also involved in the regulation of the P105 promoter using two HPV18-positive CC cell lines, SKG-I and HeLa. Following the HOXD9 knockdown, cell viability was significantly reduced, and E6 expression was suppressed and was accompanied by increased protein levels of P53, while mRNA levels of TP53 did not change. E7 expression was also downregulated and, while mRNA levels of RB1 and E2F were unchanged, mRNA levels of E2F-target genes, MCM2 and PCNA, were decreased, which indicates that the HOXD9 knockdown downregulates E7 expression, thus leading to an inactivation of E2F and the cell-cycle arrest. Chromatin immunoprecipitation and promoter reporter assays confirmed that HOXD9 is directly associated with the P105 promoter. Collectively, our results reveal that HOXD9 drives the HPV18 early promoter activity to promote proliferation and immortalization of the CC cells.
Improving Biologics’ Effectiveness in Clinical Oncology: From the Combination of Two Monoclonal Antibodies to Oligoclonal Antibody Mixtures
Authors: Larbouret Christel , Gros Laurent , Pèlegrin André , Chardès Thierry
Published: September 2021

Monoclonal antibodies have revolutionized the treatment of many diseases, but their clinical efficacy remains limited in some other cases. Pre-clinical and clinical trials have shown that combinations of antibodies that bind to the same target (homo-combinations) or to different targets (hetero-combinations) to mimic the polyclonal humoral immune response improve their therapeutic effects in cancer. The approval of the trastuzumab/pertuzumab combination for breast cancer and then of the ipilimumab/nivolumab combination for melanoma opened the way to novel antibody combinations or oligoclonal antibody mixtures as more effective biologics for cancer management. We found more than 300 phase II/III clinical trials on antibody combinations, with/without chemotherapy, radiotherapy, small molecules or vaccines, in the ClinicalTrials.gov database. Such combinations enhance the biological responses and bypass the resistance mechanisms observed with antibody monotherapy. Usually, such antibody combinations are administered sequentially as separate formulations. Combined formulations have also been developed in which separately produced antibodies are mixed before administration or are produced simultaneously in a single cell line or a single batch of different cell lines as a polyclonal master cell bank. The regulation, toxicity and injection sequence of these oligoclonal antibody mixtures still need to be addressed in order to optimize their delivery and their therapeutic effects.
Lower Survival and Increased Circulating Suppressor Cells in Patients with Relapsed/Refractory Diffuse Large B-Cell Lymphoma with Deficit of Vitamin D Levels Using R-GDP Plus Lenalidomide (R2-GDP): Results from the R2-GDP-GOTEL Trial
Authors: Jiménez-Cortegana Carlos , Sánchez-Martínez Pilar M. , Palazón-Carrión Natalia , Nogales-Fernández Esteban , Henao-Carrasco Fernando , Martín García-Sancho Alejandro , Rueda Antonio , Provencio Mariano , de la Cruz-Merino Luis , Sánchez-Margalet Víctor
Published: September 2021

The search of prognostic factors is a priority in diffuse large B-cell lymphoma (DLBCL) due to its aggressiveness. We have recently found that the level of circulating MDSCs is a good marker of survival in a translational study based on a trial (EudraCT Number: 2014-001620-29), using lenalidomide combined with R-GDP (rituximab plus gemcitabine, cisplatin, and dexamethasone). Since Vitamin D is a known immunomodulator, we have studied blood levels of these cell populations comparing patients with deficit of vitamin D levels (<15 ng/mL with those with normal levels >15 ng/mL. Mann–Whitney U test was used to compare cells distributions between groups, Wilcoxon test to compare cells distribution at different times and Spearman test to measure the association between cell populations. Patients with vitamin D deficit maintained the increased level of immune suppressor cells, whereas we observed a depletion of all immune suppressor cells in patients with normal vitamin D levels. In conclusion, we have confirmed the importance of vitamin D in the response to treatment in R/R DLBCL, suggesting that vitamin D deficit may be involved in the immune deficit of these patients, and thus, vitamin D supplementation in these patients may help to obtain a better response, warranting further investigation.
Reinforcement Learning for Precision Oncology
Authors: Eckardt Jan-Niklas , Wendt Karsten , Bornhäuser Martin , Middeke Jan Moritz
Published: September 2021

Precision oncology is grounded in the increasing understanding of genetic and molecular mechanisms that underly malignant disease and offer different treatment pathways for the individual patient. The growing complexity of medical data has led to the implementation of machine learning techniques that are vastly applied for risk assessment and outcome prediction using either supervised or unsupervised learning. Still largely overlooked is reinforcement learning (RL) that addresses sequential tasks by exploring the underlying dynamics of an environment and shaping it by taking actions in order to maximize cumulative rewards over time, thereby achieving optimal long-term outcomes. Recent breakthroughs in RL demonstrated remarkable results in gameplay and autonomous driving, often achieving human-like or even superhuman performance. While this type of machine learning holds the potential to become a helpful decision support tool, it comes with a set of distinctive challenges that need to be addressed to ensure applicability, validity and safety. In this review, we highlight recent advances of RL focusing on studies in oncology and point out current challenges and pitfalls that need to be accounted for in future studies in order to successfully develop RL-based decision support systems for precision oncology.
Targeting OLFML3 in Colorectal Cancer Suppresses Tumor Growth and Angiogenesis, and Increases the Efficacy of Anti-PD1 Based Immunotherapy
Authors: Stalin Jimmy , Imhof Beat A. , Coquoz Oriana , Jeitziner Rachel , Hammel Philippe , McKee Thomas A. , Jemelin Stephane , Poittevin Marine , Pocard Marc , Matthes Thomas , Kaci Rachid , Delorenzi Mauro , Rüegg Curzio , Miljkovic-Licina Marijana
Published: September 2021

The role of the proangiogenic factor olfactomedin-like 3 (OLFML3) in cancer is unclear. To characterize OLFML3 expression in human cancer and its role during tumor development, we undertook tissue expression studies, gene expression analyses of patient tumor samples, in vivo studies in mouse cancer models, and in vitro coculture experiments. OLFML3 was expressed at high levels, mainly in blood vessels, in multiple human cancers. We focused on colorectal cancer (CRC), as elevated expression of OLFML3 mRNA correlated with shorter relapse-free survival, higher tumor grade, and angiogenic microsatellite stable consensus molecular subtype 4 (CMS4). Treatment of multiple in vivo tumor models with OLFML3-blocking antibodies and deletion of the Olfml3 gene from mice decreased lymphangiogenesis, pericyte coverage, and tumor growth. Antibody-mediated blockade of OLFML3 and deletion of host Olfml3 decreased the recruitment of tumor-promoting tumor-associated macrophages and increased infiltration of the tumor microenvironment by NKT cells. Importantly, targeting OLFML3 increased the antitumor efficacy of anti-PD-1 checkpoint inhibitor therapy. Taken together, the results demonstrate that OLFML3 is a promising candidate therapeutic target for CRC.
Clinical Functional Genomics
Authors: Carpenter Seren , Conlan R.
Published: September 2021

Functional genomics is the study of how the genome and its products, including RNA and proteins, function and interact to affect different biological processes. The field of functional genomics includes transcriptomics, proteomics, metabolomics and epigenomics, as these all relate to controlling the genome leading to expression of particular phenotypes. By studying whole genomes—clinical genomics, transcriptomes and epigenomes—functional genomics allows the exploration of the diverse relationship between genotype and phenotype, not only for humans as a species but also in individuals, allowing an understanding and evaluation of how the functional genome ‘contributes’ to different diseases. Functional variation in disease can help us better understand that disease, although it is currently limited in terms of ethnic diversity, and will ultimately give way to more personalized treatment plans.
Niclosamide and Pyrvinium Are Both Potential Therapeutics for Osteosarcoma, Inhibiting Wnt–Axin2–Snail Cascade
Authors: Yi Young , Woo Young Mi , Hwang Kyu Ho , Kim Hyun Sil , Lee Sang Hyeong
Published: September 2021

Osteosarcoma, the most common primary bone malignancy, is typically related to growth spurts during adolescence. Prognosis is very poor for patients with metastatic or recurrent osteosarcoma, with survival rates of only 20–30%. Epithelial–mesenchymal transition (EMT) is a cellular mechanism that contributes to the invasion and metastasis of cancer cells, and Wnt signaling activates the EMT program by stabilizing Snail and β-catenin in tandem. Although the Wnt/Snail axis is known to play significant roles in the progression of osteosarcoma, and the anthelmintic agents, niclosamide and pyrvinium, have been studied as inhibitors of the Wnt pathway, their therapeutic effects and regulatory mechanisms in osteosarcoma remain unidentified. In this study, we show that both niclosamide and pyrvinium target Axin2, resulting in the suppression of EMT by the inhibition of the Wnt/Snail axis in osteosarcoma cells. Axin2 and Snail are abundant in patient samples and cell lines of osteosarcoma. The treatment of niclosamide and pyrvinium inhibits the migration of osteosarcoma cells at nanomolar concentrations. These results suggest that Axin2 and Snail are candidate therapeutic targets in osteosarcoma, and that anthelminthic agents, niclosamide and pyrvinium, may be effective for osteosarcoma patients.
Generation of Antibody-Drug Conjugate Resistant Models
Authors: Gandullo-Sánchez Lucía , Ocaña Alberto , Pandiella Atanasio
Published: September 2021

In the last 20 years, antibody-drug conjugates (ADCs) have been incorporated into the oncology clinic as treatments for several types of cancer. So far, the Food and Drug Administration (FDA) has approved 11 ADCs and other ADCs are in the late stages of clinical development. Despite the efficacy of this type of drug, the tumors of some patients may result in resistance to ADCs. Due to this, it is essential not only to comprehend resistance mechanisms but also to develop strategies to overcome resistance to ADCs. To reach these goals, the generation and use of preclinical models to study those mechanisms of resistance are critical. Some cells or patient tumors may result in primary resistance to the action of an ADC, even if they express the antigen against which the ADC is directed. Isolated primary tumoral cells, cell lines, or patient explants (patient-derived xenografts) with these characteristics can be used to study primary resistance. The most common method to generate models of secondary resistance is to treat cancer cell lines or tumors with an ADC. Two strategies, either continuous treatment with the ADC or intermittent treatment, have successfully been used to develop those resistance models.
Evaluation of 3,3′-Triazolyl Biisoquinoline N,N′-Dioxide Catalysts for Asymmetric Hydrosilylation of Hydrazones with Trichlorosilane
Authors: Sun Shiyu , Xu Changgong , Jarvis Jamielyn , Nader Phillip , Naumann Brandon , Soliven Abigail , Peverati Roberto , Takenaka Norito
Published: September 2021

A new class of axial-chiral biisoquinoline N,N′-dioxides was evaluated as catalysts for the enantioselective hydrosilylation of acyl hydrazones with trichlorosilane. While these catalysts provided poor to moderate reactivity and enantioselectivity, this study represents the first example of the organocatalytic asymmetric reduction of acyl hydrazones. In addition, the structures and energies of two possible diastereomeric catalyst–trichlorosilane complexes (2a–HSiCl3) were analyzed using density functional theory calculations.
Influence of Cs Promoter on Ethanol Steam-Reforming Selectivity of Pt/m-ZrO2 Catalysts at Low Temperature
Authors: Rajabi Zahra , Jones Li , Martinelli Michela , Qian Dali , Cronauer Donald C. , Kropf A. Jeremy , Watson Caleb D. , Jacobs Gary
Published: September 2021

The decarboxylation pathway in ethanol steam reforming ultimately favors higher selectivity to hydrogen over the decarbonylation mechanism. The addition of an optimized amount of Cs to Pt/m-ZrO2 catalysts increases the basicity and promotes the decarboxylation route, converting ethanol to mainly H2, CO2, and CH4 at low temperature with virtually no decarbonylation being detected. This offers the potential to feed the product stream into a conventional methane steam reformer for the production of hydrogen with higher selectivity. DRIFTS and the temperature-programmed reaction of ethanol steam reforming, as well as fixed bed catalyst testing, revealed that the addition of just 2.9% Cs was able to stave off decarbonylation almost completely by attenuating the metallic function. This occurs with a decrease in ethanol conversion of just 16% relative to the undoped catalyst. In comparison with our previous work with Na, this amount is—on an equivalent atomic basis—just 28% of the amount of Na that is required to achieve the same effect. Thus, Cs is a much more efficient promoter than Na in facilitating decarboxylation.
Continuous Diastereomeric Kinetic Resolution—Silybins A and B
Authors: Biedermann David , Hurtová Martina , Benada Oldřich , Valentová Kateřina , Biedermannová Lada , Křen Vladimír
Published: September 2021

The natural diastereomeric mixture of silybins A and B is often used (and considered) as a single flavonolignan isolated from the fruit extract of milk thistle (Silybum marianum), silymarin. However, optically pure silybin diastereomers are required for the evaluation of their biological activity. The separation of silybin diastereomers by standard chromatographic methods is not trivial. Preparative chemoenzymatic resolution of silybin diastereomers has been published, but its optimization and scale-up are needed. Here we present a continuous flow reactor for the chemoenzymatic kinetic resolution of silybin diastereomers catalyzed by Candida antarctica lipase B (CALB) immobilized on acrylic resin beads (Novozym® 435). Temperature, flow rate, and starting material concentration were varied to determine optimal reaction conditions. The variables observed were conversion and diastereomeric ratio. Optimal conditions were chosen to allow kilogram-scale reactions and were determined to be −5 °C, 8 g/L silybin, and a flow rate of 16 mL/min. No significant carrier degradation was observed after approximately 30 cycles (30 days). Under optimal conditions and using a 1000 × 15 mm column, 20 g of silybin per day can be easily processed, yielding 6.7 and 5.6 g of silybin A and silybin B, respectively. Further scale-up depends only on the size of the reactor.
Remodeling of Cardiac Gap Junctional Cell–Cell Coupling
Authors: Dhein Stefan , Salameh Aida
Published: September 2021

The heart works as a functional syncytium, which is realized via cell-cell coupling maintained by gap junction channels. These channels connect two adjacent cells, so that action potentials can be transferred. Each cell contributes a hexameric hemichannel (=connexon), formed by protein subuntis named connexins. These hemichannels dock to each other and form the gap junction channel. This channel works as a low ohmic resistor also allowing the passage of small molecules up to 1000 Dalton. Connexins are a protein family comprising of 21 isoforms in humans. In the heart, the main isoforms are Cx43 (the 43 kDa connexin; ubiquitous), Cx40 (mostly in atrium and specific conduction system), and Cx45 (in early developmental states, in the conduction system, and between fibroblasts and cardiomyocytes). These gap junction channels are mainly located at the polar region of the cardiomyocytes and thus contribute to the anisotropic pattern of cardiac electrical conductivity. While in the beginning the cell–cell coupling was considered to be static, similar to an anatomically defined structure, we have learned in the past decades that gap junctions are also subject to cardiac remodeling processes in cardiac disease such as atrial fibrillation, myocardial infarction, or cardiomyopathy. The underlying remodeling processes include the modulation of connexin expression by e.g., angiotensin, endothelin, or catecholamines, as well as the modulation of the localization of the gap junctions e.g., by the direction and strength of local mechanical forces. A reduction in connexin expression can result in a reduced conduction velocity. The alteration of gap junction localization has been shown to result in altered pathways of conduction and altered anisotropy. In particular, it can produce or contribute to non-uniformity of anisotropy, and thereby can pre-form an arrhythmogenic substrate. Interestingly, these remodeling processes seem to be susceptible to certain pharmacological treatment.
Colorants: A New Journal Bringing Colour to Life
Authors: Harriman Anthony
Published: September 2021

Colorant: A substance which is used to impart colour to another material! [...]
The Role of Orbital Nesting in the Superconductivity of Iron-Based Superconductors
Authors: Fernández-Martín Raquel , Calderón María J. , Fanfarillo Laura , Valenzuela Belén
Published: September 2021

We analyze the magnetic excitations and the spin-mediated superconductivity in iron-based superconductors within a low energy model that operates in the band basis, but fully incorporates the orbital character of the spin excitations. We show how the orbital selectivity, encoded in our low energy description, simplifies substantially the analysis and allows for analytical treatments, while retaining all the main features of both spin excitations and gap functions computed using multiorbital models. Importantly, our analysis unveils the orbital matching between the hole and electron pockets as the key parameter to determine the momentum dependence and the hierarchy of the superconducting gaps, instead of the Fermi surface matching, as in the common nesting scenario.
Calcium Carbonate Growth with the Ring Structure of Stalactite-Type Minerals in a Tuff Breccia
Authors: Uenishi Ryo , Matsubara Hitoshi
Published: September 2021

Microbially induced carbonate precipitation (MICP) has attracted worldwide attention as an environmentally friendly ground restoration technology in response to geohazards. This study describes the relationship between calcium carbonate growth within stalactite-type minerals formed around fractures in tuff breccia and microorganisms. Scanning electron microscopy revealed that calcium carbonate was precipitated in the interstices of rings formed in stalactite-type minerals, as if the carbonate minerals enhanced the strength of the silicate minerals. In addition, X-ray powder diffraction analysis detected that the calcium carbonates were calcite and vaterite. Moreover, microorganisms, such as diatoms and green algae, inhabited the interstices and, consequently, MICP by these microorganisms could play a role in the stability of outcrops. The stable isotope ratios of δ13C and δ15N and the mass spectral signals of the demineralized samples also encouraged diatoms and green algae to be involved in the formation of minerals.
Clinical Efficacy of Novel Patient-Covering Negative-Pressure Box for Shielding Virus Transmission during Esophagogastroduodenoscopy: A Prospective Observational Study
Authors: Fujihara Shintaro , Kobara Hideki , Nishiyama Noriko , Tada Naoya , Kozuka Kazuhiro , Matsui Takanori , Chiyo Taiga , Kobayashi Nobuya , Shi Tingting , Yachida Tatsuo , Uchida Toshio , Nagatomi Taichi , Oba Haruo , Masaki Tsutomu
Published: September 2021

Esophagogastroduodenoscopy (EGD) has a high risk of virus transmission during the current coronavirus disease 2019 era, and preventive measures are under investigation. We investigated the effectiveness of a newly developed patient-covering negative-pressure box system (Endo barrier®) (EB) for EGD. Eighty consecutive unsedated patients who underwent screening EGD with EB use were prospectively enrolled. To examine the aerosol ratio before, during, and after EGD, 0.3- and 0.5-μm aerosols were measured every 60 s using an optical counter. Moreover, the degree of contamination of the examiners’ goggles and vinyl gowns was assessed before and after EGD using a rapid adenosine triphosphate (ATP) test for simulated droplets. Data were available in 73 patients and showed that 0.3- and 0.5-μm particles did not increase in 95.8% (70/73) and 94.5% (69/73) of patients during EGD under EB. There were no significant differences in the total 0.3- or 0.5-μm particle counts before versus after EGD. The difference in the ATP levels before and after EGD was −0.6 ± 16.6 relative light units (RLU) on goggles and 1.59 ± 19.9 RLU on gowns (both within the cutoff value). EB use during EGD may provide a certain preventive effect against aerosols and droplets, decreasing examiners’ exposure to viruses.
Understanding Changes in the Topology and Geometry of Financial Market Correlations during a Market Crash
Authors: Yen Peter Tsung-Wen , Xia Kelin , Cheong Siew Ann
Published: September 2021

In econophysics, the achievements of information filtering methods over the past 20 years, such as the minimal spanning tree (MST) by Mantegna and the planar maximally filtered graph (PMFG) by Tumminello et al., should be celebrated. Here, we show how one can systematically improve upon this paradigm along two separate directions. First, we used topological data analysis (TDA) to extend the notions of nodes and links in networks to faces, tetrahedrons, or k-simplices in simplicial complexes. Second, we used the Ollivier-Ricci curvature (ORC) to acquire geometric information that cannot be provided by simple information filtering. In this sense, MSTs and PMFGs are but first steps to revealing the topological backbones of financial networks. This is something that TDA can elucidate more fully, following which the ORC can help us flesh out the geometry of financial networks. We applied these two approaches to a recent stock market crash in Taiwan and found that, beyond fusions and fissions, other non-fusion/fission processes such as cavitation, annihilation, rupture, healing, and puncture might also be important. We also successfully identified neck regions that emerged during the crash, based on their negative ORCs, and performed a case study on one such neck region.
Helping Pregraduate Students Reach Deep Understanding of the Second Law of Thermodynamics
Authors: Atarés Lorena , Canet M. Jose , Trujillo Macarena , Benlloch-Dualde José Vte. , Paricio Royo Javier , Fernandez-March Amparo
Published: September 2021

Pregraduate students often have low success expectations toward their thermodynamics courses, which are often considered too abstract and remarkably difficult to understand. For this reason, they may not even try to reach any level of comprehension while settling for reproducing mathematical calculations and memorizing definitions to pass the exams. Traditional lectures on thermodynamics, focusing on mathematical deductions while neglecting the qualitative characterization of the concepts behind the equations, do not help in this respect. Aiming at a change in the teaching practice and focused on the second law of thermodynamics, the main goals of this work are to characterize the way of reasoning of the expert; to present a review on the most important learning difficulties encountered by students and categorize them into three groups: the disregard of qualitative understanding, the inherent conceptual difficulties, and those related to the students’ previous knowledge; and to propose some suitable teaching practices to assist instructors in this difficult but rewarding task.
Assessment of Cognitive Student Engagement Using Heart Rate Data in Distance Learning during COVID-19
Authors: Ladino Nocua Andrea Catalina , Cruz Gonzalez Joan Paola , Castiblanco Jimenez Ivonne Angelica , Gomez Acevedo Juan Sebastian , Marcolin Federica , Vezzetti Enrico
Published: September 2021

Student engagement allows educational institutions to make better decisions regarding teaching methodologies, methods for evaluating the quality of education, and ways to provide timely feedback. Due to the COVID-19 pandemic, identifying cognitive student engagement in distance learning has been a challenge in higher education institutions. In this study, we implemented a non-self-report method assessing students’ heart rate data to identify the cognitive engagement during active learning activities. Additionally, as a supplementary tool, we applied a previously validated self-report method. This study was performed in distance learning lessons on a group of university students in Bogota, Colombia. After data analysis, we validated five hypotheses and compared the results from both methods. The results confirmed that the heart rate assessment had a statistically significant difference with respect to the baseline during active learning activities, and this variance could be positive or negative. In addition, the results show that if students are previously advised that they will have to develop an a new task after a passive learning activity (such as a video projection), their heart rate will tend to increase and consequently, their cognitive engagement will also increase. We expect this study to provide input for future research assessing student cognitive engagement using physiological parameters as a tool.
Highly Flexible Polyaniline-Based Implantable Electrode Materials for Neural Sensing/Stimulation Applications
Authors: Almufleh Nader , Al-Othman Amani , Alani Zaid , Al-Sayah Mohammad H. , Al-Nashash Hasan
Published: September 2021

Implantable bioelectrodes have the potential to advance neural sensing and muscle stimulation, mainly in patients with peripheral nerve injuries. They function as the transducer at the interface between the damaged nerve and the muscle which is controlled by that nerve. This work reports the fabrication and characterization of novel, low-cost, flexible bioelectrodes based on polyaniline (PANI) and supported with silicone polymer. The fabricated electrodes were evaluated for their electrical and mechanical characteristics. PANI was used as the main transducer component in this fabrication. The characterization methods included electrical conductivity, capacitive behavior, long-term electrical impedance, and mechanical evaluation. The results of the fabricated PANI-silicone-based samples displayed a bulk impedance of 0.6 kΩ with an impedance of 1.6 kΩ at the frequency of 1 kHz. Furthermore, the bioelectrodes showed a charge storage capacity range from 0.0730 to 4.3124 C/cm2. The samples were stable when subjected to cyclic voltammetry tests. The bioelectrodes revealed very flexible mechanical properties as observed from the value of Young’s modulus (in the order of MPa) which was less than that of skin. Hence, the PANI-based bioelectrodes reported herein showed promising electrochemical characteristics with high flexibility.
Assessment of Conducted Emission for Multiple Compact Fluorescent Lamps in Various Grid Topology
Authors: Long Lok Choon , Sayed Waseem El , Munesswaran Venkatkumar , Moonen Niek , Smolenski Robert , Lezynski Piotr
Published: September 2021

This paper presents the measurement of aggregated conducted emission in the frequency range of 9 kHz to 150 kHz produced by multiple compact fluorescent lamps (CFL) and how it equates to a multiple power converter system. Discrepancies in peak emission measurement results related to this application are illustrated to understand the underlying issue related to volatility of frequency components. Furthermore, this knowledge analyzes the relation of electromagnetic disturbances with respect to different topological network connections. The final presented results constitute theoretical description and statistical information about the characteristics of conducted emission measured in this multi-converter system.
Thermoplastic RTM: Impact Properties of Anionically Polymerised Polyamide 6 Composites for Structural Automotive Parts
Authors: Murray James J. , Allen Tom , Bickerton Simon , Bajpai Ankur , Gleich Klaus , McCarthy Edward D. , Ó Brádaigh Conchúr M.
Published: September 2021

This study investigates the impact behaviour and post-impact performance of polyamide-6 glass fibre reinforced composites, manufactured by thermoplastic resin transfer moulding. Impact test samples were extracted from quasi-isotropic laminates using two different glass fibre sizings, both with a fibre volume fraction of approximately 52%. A previous study showed that one of these sizings enhanced the interfacial strength and Mode I fracture toughness; however, the effects of the sizing on out-of-plane impact is of greater significance in terms of automotive applications. A drop-weight impact tester was used to determine out-of-plane impact performance for both sizings in terms of impact load-induced and energy returned from the striker. High-speed video of the impact response was simultaneously captured. Testing was carried out at three impact energy levels: two sub-penetration and one full penetration. The impact damage area was observed, and the post-damage compression properties of samples were measured to determine the reduction in their strength and stiffness. Results showed that the use of different sizing technologies had little effect on the post-impact compressive properties and that penetration led to only a 29% drop in compression strength. Overall, the outcomes of this work demonstrate the potential of these materials in automotive applications.
Comparison of AC and DC Nanogrid for Office Buildings with EV Charging, PV and Battery Storage
Authors: Sulaeman Ilman , Chandra Mouli Gautham Ram , Shekhar Aditya , Bauer Pavol
Published: September 2021

Future office buildings are expected to be integrated with energy intensive, inherently DC components such as photovoltaic panels (PV), electric vehicles (EV), LED lighting, and battery storage. This paper conceptualizes the interconnection of these components through a 750 V DC nanogrid as against a conventional three-phase 400 V AC system. The factors influencing the performance of a DC-based nanogrid are identified and a comparative analysis with respect to a conventional AC nanogrid is presented in terms of efficiency, stability, and protection. It is proved how the minimization of grid energy exchange through power management is a vital system design choice. Secondly, the trade-off between stability, protection, and cost for sizing of the DC buffer capacitors is explored. The transient system response to different fault conditions for both AC and DC nanogrid is investigated. Finally the differences between the two systems in terms of various safety aspects are highlighted.
The Problem of Non-Typical Objects in the Multidimensional Comparative Analysis of the Level of Renewable Energy Development
Authors: Piwowarski Mateusz , Borawski Mariusz , Nermend Kesra
Published: September 2021

The development of energy from renewable sources is one of the most important aspects of today’s energy industry. The level of this development (production of green energy) is determined by the use of a variety of methods, e.g., the methods of multicriteria and multivariate analysis. The effectiveness of these methods is affected by many factors, and one of them is the appearance of non-typical objects (outliers). This paper investigates the effectiveness of selected methods (TOPSIS, VIKOR, VMCM) in terms of computational robustness to outlier objects. The most effective method in this respect (VMCM) is then applied to study the level of development of renewable energy sources in European countries. The presented research provides the opportunity to carry out a dynamic analysis (for selected base years) of the level of energy generation from diverse renewable sources in reference to the adopted patterns and anti-patterns (European countries). The obtained results are discussed, thus confirming the effectiveness of the proposed methodological approach.
Predictive Maintenance Framework for Cathodic Protection Systems Using Data Analytics
Authors: Rossouw Estelle , Doorsamy Wesley
Published: September 2021

In the quest to achieve sustainable pipeline operations and improve pipeline safety, effective corrosion control and improved maintenance paradigms are required. For underground pipelines, external corrosion prevention mechanisms include either a pipeline coating or impressed current cathodic protection (ICCP). For extensive pipeline networks, time-based preventative maintenance of ICCP units can degrade the CP system’s integrity between maintenance intervals since it can result in an undetected loss of CP (forced corrosion) or excessive supply of CP (pipeline wrapping disbondment). A conformance evaluation determines the CP system effectiveness to the CP pipe potentials criteria in the NACE SP0169-2013 CP standard for steel pipelines (as per intervals specified in the 49 CFR Part 192 statute). This paper presents a predictive maintenance framework based on the core function of the ICCP system (i.e., regulating the CP pipe potential according to the NACE SP0169-2013 operating window). The framework includes modeling and predicting the ICCP unit and the downstream test post (TP) state using historical CP data and machine learning techniques (regression and classification). The results are discussed for ICCP units operating either at steady state or with stray currents. This paper also presents a method to estimate the downstream TP’s CP pipe potential based on the multiple linear regression coefficients for the supplying ICCP unit. A maintenance matrix is presented to remedy the defined ICCP unit states, and the maintenance time suggestion is evaluated using survival analysis, cycle times, and time-series trend analysis.
Selected Issues of Safe Operation of the Railway Traffic Control System in the Event of Exposition to Damage Caused by Lightning Discharges
Authors: Markowska Renata , Wróbel Zofia
Published: September 2021

Lightning discharge becomes a serious source of interference and damage for electronic and electrical power systems. Safe and reliable operation of railway traffic control systems requires proper protection against the effects of lightning. However, the current standards on lightning protection, PN-EN/EN/IEC 62305, do not cover railway objects. Moreover, there are no other standards or recommendations dedicated to the railway. The paper is an attempt to apply the procedure of lightning risk management according to PN-EN 62305-2 to select the proper protection measures in railway objects. A case study for the signal box with installed relaying and digital stations of the railway traffic control system is analyzed. The analysis comprises calculations based on the current standard PN-EN 62305-2:2012 but including the issues specific to railway traffic control. The risks of lightning losses have been calculated for two cases: without lightning protection measures and with protection measures proposed to decrease the risks below the tolerable values. The results show that a practically effective solution to reduce the risks is applying surge protective devices with proper characteristics. Another way is replacing unshielded incoming lines with shielded ones of given shield bonding way, and supplementing it with surge protective devices when necessary.
Stress-Testing MQTT Brokers: A Comparative Analysis of Performance Measurements
Authors: Mishra Biswajeeban , Mishra Biswaranjan , Kertesz Attila
Published: September 2021

Presently, Internet of Things (IoT) protocols are at the heart of Machine-to-Machine (M2M) communication. Irrespective of the radio technologies used for deploying an IoT/M2M network, all independent data generated by IoT devices (sensors and actuators) rely heavily on the special messaging protocols used for M2M communication in IoT applications. As the demand for IoT services is growing, the need for reduced power consumption of IoT devices and services is also growing to ensure a sustainable environment for future generations. The Message-Queuing Telemetry Transport or in short MQTT is a widely used IoT protocol. It is a low-resource-consuming messaging solution based on the publish–subscribe type communication model. This paper aims to assess the performance of several MQTT broker implementations (also known as MQTT servers) using stress testing, and to analyze their relationship with system design. The evaluation of the brokers is performed by a realistic test scenario, and the analysis of the test results is done with three different metrics: CPU usage, latency, and message rate. As the main contribution of this work, we analyzed six MQTT brokers (Mosquitto, Active-MQ, Hivemq, Bevywise, VerneMQ, and EMQ X) in detail, and classified them using their main properties. Our results showed that Mosquitto outperforms the other considered solutions in most metrics; however, ActiveMQ is the best performing one in terms of scalability due to its multi-threaded implementation, while Bevywise has promising results for resource-constrained scenarios.
Potential Climate Change Risks to Meeting Zimbabwe’s NDC Goals and How to Become Resilient
Authors: Howells Mark , Boehlert Brent , Benitez Pablo César
Published: September 2021

Almost all countries have committed to develop Nationally Determined Contributions (NDC) to reduce GHG emissions. They determine the level of GHG mitigation that, as a nation, they will commit to reducing. Zimbabwe has ambitious and laudable GHG mitigation targets. Compared to a coal-based future, emissions will be reduced by 33% per capita by 2030. If historical climate conditions continue, it can do this at low or negative cost if suitable sources of climate financing are in place. The NDC plots a positive future. However, much of Zimbabwe’s NDC mitigation center on hydropower generation and other measures that are dangerously vulnerable to climate change. Should the climate change in accordance with recent projections, these investments will be at risk, severely constraining electricity supply and causing high degrees of economic damage. This paper uses the Open-Source energy Modelling SYStem (OSeMOSYS) to consider two adaptation pathways that address this vulnerability. In the first, the country turns to a historically accessible option, namely the deployment of coal. In so doing, the electrical system is made more resilient, but emissions ramp up. The second pathway ‘climate proofs’ the power sector by boosting solar and wind capacity, using hydropower to provide balance for these new renewable resources, and introducing significant energy efficiency measures. This second pathway would require a set of extra accompanying investments and changes to the power market rules, but allows for both system resilience and NDC targets to be met. The paper shows that Zimbabwe’s low emissions growth can be made resilient, and while this path promises strong benefits, it also requires strong commitment and political will. From this paper insights are drawn and requirements for future analysis are made. Two critical insights are that: (i) NDCs that focus on mitigation should include resilience in their design. If they do not, they can introduce deep vulnerability; (ii) a departure from historical electricity market structures appears to hold potential for strong environmental, cost and reliability gains.
Analysis of Spatial Effects in the Relationship between CO2 Emissions and Renewable Energy Consumption in the Context of Economic Growth
Authors: Jankiewicz Mateusz , Szulc Elżbieta
Published: September 2021

The paper presents a spatial approach to the analysis of the relationship between air pollution, economic growth, and renewable energy consumption. The economic growth of every country is based on the energy consumption that leads to an increase in national productivity. Using renewable energy is very important for the environmental protection and security of the earth’s resources. Promoting environmentally friendly operations increases awareness of sustainable development, which is currently a major concern of state governments. In this study, we explored the influence of economic growth and the share of renewable energy out of total energy consumption on CO2 emissions. The study was based on the classical environmental Kuznets curve (EKC) and enriched with the spatial dependencies. In particular, we determined the spatial spillovers in the form of the indirect effects of changes in renewable energy consumption of a specific country on the CO2 emissions of neighboring countries. A neighborhood in this study was defined by ecological development similarity. The neighborhood matrix was constructed based on the values of the ecological footprint measure. We used the spatio-temporal Durbin model, with which the indirect effects were determined in relation to the spatially lagged renewable energy consumption. The results of our study also show the strength of the effects caused by imitating actions from the states with high levels of environmental protection. The study was conducted using data for 75 selected countries from the period of 2013–2019. Cumulative spatial and spatio-temporal effects allowed us to determine (1) the countries with the greatest impact on others and (2) the countries that follow the leading ones.
Effects of Bypass Flow Distribution on Cold Flow Characteristics of Integrated Afterburner
Authors: Jia Xiangzhong , Shan Yong , Xu Xingping , Zhang Jingzhou , Tan Xiaoming
Published: September 2021

Integrated design is a trend in the development of afterburners, and the distribution of cold flow is directly related to their flow field characteristics, combustion organization, and the cooling effect of components. Numerical simulations were performed to illustrate the effects of bypass flow distribution on the flow distribution, mixing characteristics, and cooling efficiency of the components by varying the cooling flow path structure parameters. Within the range of parameters in this study, it can be indicated that with the increase of heat shield inlet height and afterburner annulus height, the total pressure recovery coefficient along the path increased accordingly, and the increasing rate at the afterburner outlet is 1.12% and 1.19%, respectively. The average cooling efficiency of radial flameholder, circumferential flameholder, and fuel injector all decrease, but the rate of decrease varies slightly depending on the location of the components. The increase of heat shield inlet height would reduce thermal mixing efficiency by approximately 5.4% at the afterburner outlet, and the increase of afterburner annular height would increase about 2.9%.
Experimental Validation of Flow Uniformity Improvement by a Perforated Plate in the Heat Exchanger of SFR Steam Generator
Authors: Kim Myung-Ho , Nguyen Van Toan , Im Sunghyuk , Jung Yohan , Choi Sun-Rock , Kim Byoung-Jae
Published: September 2021

The steam generator in a nuclear power plant is a type of heat exchanger in which heat transfer occurs from the hot fluid in multiple channels to the cold fluid. Therefore, a uniform flow over multiple channels is necessary to improve heat exchanger efficiency. The study aims at experimentally investigating the improvement of flow uniformity by the perforated plate in the heat exchanger used for a sodium-cooled fast reactor stream generator. A 1/4-scale experimental model for one heat exchanger unit with 33 × 66 channels was manufactured. The working fluid was water. A perforated plate was systematically designed using numerical simulations to improve the flow uniformity over the 33 × 66 channels. As a result, the flow uniformity greatly improved at a slight cost of pressure drop. To validate the numerical results, planar particle image velocimetry measurements were performed on the selected planes in the inlet and outlet headers. The experimental velocity profiles near the exits of the channels were compared with numerical simulation data. The experimental profiles agreed with the numerical data well. Both the numerical simulation and the experimental results showed a slight increase in pressure drop, despite significant improvement in the flow uniformity.