bluuebunny/crossref_metadata_2025 huggingface dataset:
Satisfaction with Fertility Preservation Decisions among Adolescent Males with Cancer: A Mixed Methods Study
Authors: Theroux Charleen I. , Hill Kylie N. , Olsavsky Anna L. , Klosky James L. , Yeager Nicholas D. , Audino Anthony , O’Brien Sarah H. , Quinn Gwendolyn P. , Gerhardt Cynthia A. , Nahata Leena
Published: July 2021

Half of male childhood cancer survivors experience treatment-related fertility impairment, which can lead to distress. Survivors often regret forgoing fertility preservation (FP), and decisional dissatisfaction is associated with a lower quality of life. This mixed methods study examined short-term FP decisional satisfaction among families of male adolescents newly diagnosed with cancer who received an initial fertility consult and completed an FP values clarification tool. One-two months after the FP decision, thirty-nine families completed the Brief Subjective Decision Quality measure. Decisional satisfaction was compared for participants (mothers, fathers, adolescents) who did and did not attempt to bank. Semi-structured interviews included the following question: How do you/your family feel about the banking decision now/in the future? Decisional quality scores were moderate-high (M = 5.74–6.33 out of 7), with no significant differences between non-attempter (n = 15) and attempter (n = 24) families (adolescents: p = 0.83, d = 0.08; mothers: p = 0.18, d = 0.45; fathers: p = 0.32, d = 0.44). Three qualitative themes emerged among non-attempter families: (1) satisfaction with decision (50% of participants), (2) acceptance of decision (60%), and (3) potential for future regret (40%). Satisfaction with decision was the only theme identified in attempter families (93%). Quantitively, short-term decisional satisfaction was high regardless of the banking attempt. However, the qualitative findings suggest that the experiences of families who did not bank may be more nuanced, as several participants discussed a potential for future regret, highlighting the importance of ongoing support.
Correction: Yun et al. Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer. Cancers 2021, 13, 2144
Authors: Yun Chul-Won , Lee Jun-Hee , Go Gyeongyun , Jeon Juhee , Yoon Sungtae , Lee Sang-Hun
Published: July 2021

The authors wish to make the following corrections to this paper [...]
Treatment and Survival of Malignant Extracranial Germ Cell Tumours in the Paediatric Population: A Systematic Review and Meta-Analysis
Authors: Hulsker Caroline C. C. , el Mansori Issam , Fiocco Marta , Zsiros József , Wijnen Marc H. W. , Looijenga Leendert H. J. , Mavinkurve-Groothuis Annelies M. C. , van der Steeg Alida F. W.
Published: July 2021

Objective: This systematic review and meta-analysis was performed to explore overall survival (OS) and event free survival (EFS) rates internationally over the past two decades and to define specific subgroups with inferior outcomes which may demand different treatment strategies. Methods: The search focused on malignant extracranial germ cell tumours (GCTs) in the paediatric population. The initial database search identified 12,556 articles; 32 articles were finally included in this review, comprising a total of 5095 patients. Results: The studies were heterogeneous, varying from single institution reports to large prospective trials. Older studies, describing eras where non-platinum-based chemotherapy regimens were used, showed clearly worse outcomes. Survival for stage I–II gonadal disease is excellent. On the other hand, patients with an initial alpha-fetoprotein (AFP) > 10,000 ng/mL or kU/L, age > 11 years and stage IV disease confer a survival disadvantage. For testicular disease in particular, lymphovascular invasion and certain histopathological subtypes, such as embryonal carcinoma (EC) and mixed malignant GCTs, survival is poorer. Survival data for sacrococcygeal and mediastinal GCTs show a heterogeneous distribution across studies in this review, independent of year of publication. Patients > 12 years presenting with a mediastinal GCT pose a subpopulation which fares worse than GCTs in other locations or age groups. This is independent of AFP levels, stage of disease or treatment protocol, and these patients may demand a different treatment strategy. Conclusions: This review describes the heterogeneous nature of GCTs in different anatomical locations, impacting on stage at presentation, treatment modalities used and survival data. Despite this heterogeneity, in line with the current developmental biology-based classification system, subpopulations can be defined which have an inferior EFS and OS and where future research and more individualised treatment would help to improve survival.
Phosphorous Magnetic Resonance Spectroscopy and Molecular Markers in IDH1 Wild Type Glioblastoma
Authors: Galijašević Malik , Steiger Ruth , Radović Ivan , Birkl-Toeglhofer Anna Maria , Birkl Christoph , Deeg Lukas , Mangesius Stephanie , Rietzler Andreas , Regodić Milovan , Stockhammer Guenther , Freyschlag Christian Franz , Kerschbaumer Johannes , Haybaeck Johannes , Grams Astrid Ellen , Gizewski Elke Ruth
Published: July 2021

The World Health Organisation’s (WHO) classification of brain tumors requires consideration of both histological appearance and molecular characteristics. Possible differences in brain energy metabolism could be important in designing future therapeutic strategies. Forty-three patients with primary, isocitrate dehydrogenase 1 (IDH1) wild type glioblastomas (GBMs) were included in this study. Pre-operative standard MRI was obtained with additional phosphorous magnetic resonance spectroscopy (31-P-MRS) imaging. Following microsurgical resection of the tumors, biopsy specimens underwent neuropathological diagnostics including standard molecular diagnosis. The spectroscopy results were correlated with epidermal growth factor (EGFR) and O6-Methylguanine-DNA methyltransferase (MGMT) status. EGFR amplified tumors had significantly lower phosphocreatine (PCr) to adenosine triphosphate (ATP)-PCr/ATP and PCr to inorganic phosphate (Pi)-PCr/Pi ratios, and higher Pi/ATP and phosphomonoesters (PME) to phosphodiesters (PDE)-PME/PDE ratio than those without the amplification. Patients with MGMT-methylated tumors had significantly higher cerebral magnesium (Mg) values and PME/PDE ratio, while their PCr/ATP and PCr/Pi ratios were lower than in patients without the methylation. In survival analysis, not-EGFR-amplified, MGMT-methylated GBMs showed the longest survival. This group had lower PCr/Pi ratio when compared to MGMT-methylated, EGFR-amplified group. PCr/Pi ratio was lower also when compared to the MGMT-unmethylated, EGFR not-amplified group, while PCr/ATP ratio was lower than all other examined groups. Differences in energy metabolism in various molecular subtypes of wild-type-GBMs could be important information in future precision medicine approach.
Sustainable Production of Glycolipids by Biocatalyst on Renewable Deep Eutectic Solvents
Authors: Hoyos Laura V. , Ramírez Laura , Yarce Cristhian J. , Alvarez-Vasco Carlos , Caicedo Ortega Nelson H.
Published: July 2021

Glycolipids have become an ecofriendly alternative to chemically obtained surfactants, mainly for the cosmetic, pharmaceutical, and food industries. However, the sustainable production of these compounds is still challenging, because: (i) water is a recognized inhibitor, (ii) multiphases make the use of cosolvent reaction medium necessary, and (iii) there are difficulties in finding a source for both starting materials. This study used sugars and lipids from peach palm fruit shells or model compounds as substrates to synthesize glycolipids on five different renewable deep eutectic solvents (Re-DES) alone or with a cosolvent system. Substrate conversions up to 24.84% (so far, the highest reported for this reaction on DES), showing (1) the non-precipitation of glucose in the solvent, (2) emulsification and (3) low viscosity (e.g., more favorable mass transfer) as the main limiting factors for these heterogeneous enzymatic processes. The resulting conversion was reached using a cosolvent system Re-DES:DMSO:t-butanol that was robust enough to allow conversions in the range 19–25%, using either model compounds or sugar and fatty acid extracts, with free or immobilized enzymes. Finally, the characterization of the in-house synthesized glycolipids by surface tension demonstrated their potential as biosurfactants, for instance, as an alternative to alcohol ethoxylates, industrially produced using less sustainable methods.
Combination of GP88 Expression in Tumor Cells and Tumor-Infiltrating Immune Cells Is an Independent Prognostic Factor for Bladder Cancer Patients
Authors: Eckstein Markus , Lieb Verena , Jung Rudolf , Sikic Danijel , Weigelt Katrin , Stöhr Robert , Geppert Carol , Weyerer Veronika , Bertz Simone , Serrero Ginette , Yue Binbin , Hartmann Arndt , Wullich Bernd , Taubert Helge , Wach Sven
Published: July 2021

Urothelial bladder cancer (BCa) is the ninth most commonly diagnosed cancer worldwide and accounts for approximately 3% of global cancer diagnoses. We are interested in prognostic markers that may characterize tumor cells (TCs) and immune cells (ICs) and their relationship in BCa. A potential candidate marker that meets these criteria is progranulin (GP88), which is expressed separately in TCs and ICs. We analyzed GP88 expression by immunohistochemistry (IHC) in 196 muscle-invasive BCa samples using a tissue microarray. The immunoreactive score for GP88 staining in TCs and the percentage of GP88-positive ICs was determined. An easy cutoff for the staining status of TCs (positive vs. negative) and ICs (0% vs. >0%) and, more generally, negative vs. positive GP88 staining could be applied. We detected 93 patients (47.4%) and 92 patients (46.9%) with GP88-positive TCs or ICs, respectively. The IHC results were correlated with clinicopathological and survival data. Positive GP88 staining in TCs appeared to be an independent poor prognostic factor for disease-specific survival (DSS) (RR (relative risk) = 1.74; p = 0.009) and recurrence-free survival (RFS) (RR = 1.92; p = 0.002). In contrast, negative GP88 staining in ICs was an independent negative predictor for overall survival (OS) (RR = 2.18; p < 0.001), DSS (RR = 2.84; p < 0.001) and RFS (RR = 2.91; p < 0.001) in multivariate Cox’s regression analysis. When combining GP88 staining in TCs and ICs, a specific combination of GP88-positive TCs and GP88-negative ICs was associated with a 2.54-fold increased risk of death, a 4.21-fold increased risk of disease-specific death and a 4.81-fold increased risk of recurrence compared to GP88-negative TCs and GP88-positive ICs. In summary, GP88 positivity in TCs is a negative prognostic factor for DSS and RFS. In addition, GP88 positivity can mark ICs that are associated with a good prognosis (OS, DSS and RFS). The combination of GP88 staining in TCs and ICs appears to be a significant independent prognostic biomarker in muscle-invasive BCa.
NF-κB—An Important Player in Xenoestrogen Signaling in Immune Cells
Authors: Nowak Karolina , Jabłońska Ewa , Ratajczak-Wrona Wioletta
Published: July 2021

The proper functioning of the immune system is critical for an effective defense against pathogenic factors such as bacteria and viruses. All the cellular processes taking place in an organism are strictly regulated by an intracellular network of signaling pathways. In the case of immune cells, the NF-κB pathway is considered the key signaling pathway as it regulates the expression of more than 200 genes. The transcription factor NF-κB is sensitive to exogenous factors, such as xenoestrogens (XEs), which are compounds mimicking the action of endogenous estrogens and are widely distributed in the environment. Moreover, XE-induced modulation of signaling pathways may be crucial for the proper development of the immune system. In this review, we summarize the effects of XEs on the NF-κB signaling pathway. Based on our analysis, we constructed a model of XE-induced signaling in immune cells and found that in most cases XEs activate NF-κB. Our analysis indicated that the indirect impact of XEs on NF-κB in immune cells is related to the modulation of estrogen signaling and other pathways such as MAPK and JAK/STAT. We also summarize the role of these aspects of signaling in the development and further functioning of the immune system in this paper.
Evaluation of the Effects of Human Dental Pulp Stem Cells on the Biological Phenotype of Hypertrophic Keloid Fibroblasts
Authors: Yan Ming , Fu Ling-Ling , Nada Ola A. , Chen Li-Ming , Gosau Martin , Smeets Ralf , Feng Hong-Chao , Friedrich Reinhard E.
Published: July 2021

Objective: Despite numerous existing treatments for keloids, the responses in the clinic have been disappointing, due to either low efficacy or side effects. Numerous studies dealing with preclinical and clinical trials have been published about effective therapies for fibrotic diseases using mesenchymal stem cells; however, no research has yet been reported to scientifically investigate the effect of human dental pulp stem cells (HDPSCs) on the treatment of keloids. The objective is to provide an experimental basis for the application of stem cells in the treatment of keloids. Methods: Human normal fibroblasts (HNFs) and human keloid fibroblasts (HKFs) were cultured alone and in combination with HDPSCs using a transwell cell-contact-independent cell culture system. The effects of HDPSCs on HKFs were tested using a CCK-8 assay, live/dead staining assay, quantitative polymerase chain reaction, Western blot and immunofluorescence microscopy. Results: HDPSCs did not inhibit the proliferation nor the apoptosis of HKFs and HNFs. HDPSCs did, however, inhibit their migration. Furthermore, HDPSCs significantly decreased the expression of profibrotic genes (CTGF, TGF-β1 and TGF-β2) in HKFs and KNFs (p < 0.05), except for CTGF in HNFs. Moreover, HDPSCs suppressed the extracellular matrix (ECM) synthesis in HKFs, as indicated by the decreased expression of collagen I as well as the low levels of hydroxyproline in the cell culture supernatant (p < 0.05). Conclusions: The co-culture of HDPSCs inhibits the migration of HKFs and the expression of pro-fibrotic genes, while promoting the expression of anti-fibrotic genes. HDPSCs’ co-culture also inhibits the synthesis of the extracellular matrix by HKFs, whereas it does not affect the proliferation and apoptosis of HKFs. Therefore, it can be concluded that HDPSCs can themselves be used as a tool for restraining/hindering the initiation or progression of fibrotic tissue.
Environmental Odour Quantification by IOMS: Parametric vs. Non-Parametric Prediction Techniques
Authors: Zarra Tiziano , Galang Mark Gino K. , Belgiorno Vincenzo , Naddeo Vincenzo
Published: July 2021

Odour emissions are a global issue that needs to be controlled to prevent negative impacts. Instrumental odour monitoring systems (IOMS) are an intelligent technology that can be applied to continuously assess annoyance and thus avoid complaints. However, gaps to be improved in terms of accuracy in deciphering information, especially in the implementation of the mathematical model, are still being researched, especially in environmental odour monitoring applications. This research presents and discusses the implementation of traditional and innovative parametric and non-parametric prediction techniques for the elaboration of an effective odour quantification monitoring model (OQMM), with the aim of optimizing the accuracy of the measurements. Artificial neural network (ANN), multivariate adaptive regression splines (MARSpline), partial least square (PLS), multiple linear regression (MLR) and response surface regression (RSR) are implemented and compared for prediction of odour concentrations using an advanced IOMS. Experimental analyses are carried out by using real environmental odour samples collected from a municipal solid waste treatment plant. Results highlight the strengths and weaknesses of the analysed models and their accuracy in terms of environmental odour concentration prediction. The ANN application allows us to obtain the most accurate results among the investigated techniques. This paper provides useful information to select the appropriate computational tool to process the signals from sensors, in order to improve the reliability and stability of the measurements and create a robust prediction model.
Simple and Rapid Preparation of MIL-121 with Small Particles for Lithium Adsorption from Brine
Authors: Wei Qinyan , Shi Bingqian , Wang Fei , Shao Shuoshuo , Zhu Liang , Zhao Xiaoyu
Published: July 2021

A novel method to generate an aluminum-based MOF material named as MIL-121 was investigated. MIL-121, [Al(OH)(H2BTEC)·(H2O)]n is a prototypal aluminum MOF with 1,2,4,5-benzenetetracarboxylic acid (BTEC) linkers, which was normally produced by the hydrothermal method. Different from the hydrothermal method, the developed novel method does not involve high temperature and high pressure, instead the MOF material was produced by the traditional cooling crystallization method at ambient pressure and low temperature below 100 °C. The MIL-121 obtained by the novel method possesses the same lithium adsorption performance as that obtained by hydrothermal method, but with lower energy consumption and more environmentally friendly. Compared with hydrothermal method, this method has more advantage to be scaled up to industrialized production. The formation mechanism of MIL-121 in the novel method including nucleation and growth process of MOF crystal was studied. The results indicated that the size and morphology of MIL-121 crystals were influenced by the temperature and additives, respectively. As the reaction temperature increased to 100 °C, the operation time can be shortened to 2–5 h. The crystal habit that was predicted by Material studio software using BFDH, which is a model for crystal habit prediction proposed by Bravais, Friedel, Donnay, and Harker based on the crystal lattice parameters and crystal symmetry in the Morphology module, the simulated morphology of MIL-121 was in accord with that of the products obtained by cooling crystallization. The thermal stability of MIL-121 obtained by cooling crystallization is better than that obtained by the hydrothermal method.
Synthesis, Optical, Magnetic and Thermodynamic Properties of Rocksalt Li1.3Nb0.3Mn0.4O2 Cathode Material for Li-Ion Batteries
Authors: Kamel Mohamed , Hanna Abanoub R. N. , Krellner Cornelius , Klingeler Rüdiger , Abdellah Mohamed , Abdel-Hafiez Mahmoud , Hassen Arafa , Khalil Ahmed S. G. , Abdel-Baset Tarob , Hassan Abdelwahab
Published: July 2021

Since the discovery of the reversible intercalation of lithium-ion materials associated with promising electrochemical properties, lithium-containing materials have attracted attention in the research and development of effective cathode materials for lithium-ion batteries. Despite various studies on synthesis, and electrochemical properties of lithium-based materials, fairly little fundamental optical and thermodynamic studies are available in the literature. Here, we report on the structure, optical, magnetic, and thermodynamic properties of Li-excess disordered rocksalt, Li1.3Nb0.3Mn0.4O2 (LNMO) which was comprehensively studied using powder X-ray diffraction, transient absorption spectroscopy, magnetic susceptibility, and low-temperature heat capacity measurements. Charge carrier dynamics and electron–phonon coupling in LNMO were studied using ultra-fast laser spectroscopy. Magnetic susceptibility and specific heat data are consistent with the onset of long-range antiferromagnetic order at the Néel temperatures of 6.5 (1.5) K. The effective magnetic moment of LNMO is found to be 3.60 μB. The temperature dependence of the inverse magnetic susceptibility follows the Curie–Weiss law in the high-temperature region and shows negative values of the Weiss temperature 52 K (3), confirming the strong AFM interactions.
What Makes a Hot-Spring Habitat “Hot” for the Hot-Spring Snake: Distributional Data and Niche Modelling for the Genus Thermophis (Serpentes, Colubridae)
Authors: Hofmann Sylvia , Fritzsche Peter , Dorge Tsering , Miehe Georg , Nothnagel Michael
Published: July 2021

Knowledge about species’ distributions is central to diverse applications in ecology, biogeography, and conservation science. Hot-spring snakes of the genus Thermophis share a distribution restricted to geothermal sites at the Tibetan Plateau (T. baileyi) and in the Hengduan Mountains (T. zhaoermii, T. shangrila). Although the suture zones of these regions are widely covered with hot springs, Thermophis populations are restricted to only a few of these habitats. Here, we use bioclimatic, topographic, and land cover data to model the potential distribution of the genus. Moreover, using logistic regression on field survey data of T. zhaoermii, we test whether hot-spring water parameters and landscape features correlate with the species’ presence or absence. Hot springs with temperatures between 45 and 100 °C and winter precipitation showed the most predictive power. At small scale, our data support the relevance of the hot-spring temperature on the species’ occurrence and indicate that also the along-valley distance from the hot-spring site to the major river might influence the distribution of Thermophis species. Our findings contribute to better understand factors shaping the current distribution of the genus and will aid in setting priorities in applied conservation biology for the hot-spring snakes.
Cardiac Autonomic Nervous System and Ventricular Arrhythmias: The Role of Radionuclide Molecular Imaging
Authors: Fesas Andreas , Giannoula Evanthia , Vrachimis Alexis , Doumas Argyrios , Wenning Christian , Didagelos Matthaios , Iakovou Ioannis
Published: July 2021

Widely established compared to myocardial perfusion imaging, cardiac autonomous nervous system (CANS) assessment by radiopharmaceutical means is of potential use especially to arrhythmogenic diseases not correlated with anatomic or functional alterations revealed by classical imaging techniques. Molecular imaging of both pre- and postsynaptic functions of the autonomous nervous system is currently feasible, since single photon emission tomography (SPECT) and positron emission tomography (PET) have the ability to reveal the insights of molecular pathophysiology depicting both sympathetic and parasympathetic imbalance in discrete heart pathologies. This review provides not only a brief presentation of radiopharmaceuticals used for non-invasive CANS imaging in the case of ventricular arrhythmias, but also a current update on ventricular tachycardias, cardiomyopathies, Brugada and Long QT syndrome literature.
Differences in the Quantity and Composition of Extracellular Vesicles in the Aqueous Humor of Patients with Retinal Neovascular Diseases
Authors: Hsiao Yai-Ping , Chen Connie , Lee Chee-Ming , Chen Pei-Ying , Chung Wei-Heng , Wang Yu-Ping , Hung Yu-Chien , Cheng Chao-Min , Chen Chihchen , Ko Bei-Han , Hsu Min-Yen
Published: July 2021

Extracellular vesicles (EVs) are secreted by various cells in the body fluid system and have been found to influence vessel formation and inflammatory responses in a variety of diseases. However, which EVs and their subtypes are involved in vascular retinal diseases is still unclear. Therefore, the aim of this study was to explore the particle distribution of EVs in retinal neovascular diseases, including age-related macular degeneration, polypoidal choroidal vasculopathy, and central retinal vein occlusion. The aqueous humor was harvested from 20 patients with different retinal neovascular diseases and six patients with cataracts as the control group. The particle distribution was analyzed using nanoparticle tracking analysis (NTA) and transmitting electron microscopy (TEM). The results revealed that the disease groups had large amounts of EVs and their subtypes compared to the control group. After isolating exosomes, a higher expression of CD81+ exosomes was shown in the disease groups using flow cytometry. The exosomes were then further classified into three subtypes of exomeres, small exosomes, and large exosomes, and their amounts were shown to differ depending on the disease type. To the best of our knowledge, this is the first study to elucidate the dynamics of EVs in retinal neovascular diseases using clinical cases. Our findings demonstrated the possible functionality of microvesicles and exosomes, indicating the potential of exosomes in the diagnosis and therapy of retinal neovascular diseases.
Raman Spectroscopy Technique: A Non-Invasive Tool in Celiac Disease Diagnosis
Authors: Acri Giuseppe , Romano Claudio , Costa Stefano , Pellegrino Salvatore , Testagrossa Barbara
Published: July 2021

Celiac disease (CD) is diagnosed by a combination of specific serology and typical duodenal lesions. The histological confirmation of CD, mandatory in the majority of patients with suspected CD, is based on invasive and poorly tolerated procedures, such as upper gastrointestinal endoscopy. In this study we propose an alternative and non-invasive methodology able to confirm the diagnosis of CD based on the analysis of serum samples using the Raman spectroscopy technique. Three different bands centered at 1650, 1450 and 1003 cm−1 have been considered and the A1450/A1003 and A1650/A1003 ratios have been computed to discriminate between CD and non-CD subjects. The reliability of the methodology was validated by statistical analysis using receiver operating characteristic (ROC) curves. The Youden index was also determined to obtain optimal cut-off points. The obtained results highlighted that the proposed methodology was able to distinguish between CD and non-CD subjects with 98% accuracy. The optimal cut-off points revealed, for both the A1450/A1003 and A1650/A1003 ratios, high values of sensitivity and specificity (>95.0% and >92.0% respectively), confirming that Raman spectroscopy may be considered a valid alternative to duodenal biopsy and demonstrates spectral changes in the secondary structures of the protein network.
Left Ventricular Diastolic Function Studied with Magnetic Resonance Imaging: A Systematic Review of Techniques and Relation to Established Measures of Diastolic Function
Authors: Bojer Annemie Stege , Soerensen Martin Heyn , Gaede Peter , Myerson Saul , Madsen Per Lav
Published: July 2021

Purpose: In recent years, cardiac magnetic resonance (CMR) has been used to assess LV diastolic function. In this systematic review, studies were identified where CMR parameters had been evaluated in healthy and/or patient groups with proven diastolic dysfunction or known to develop heart failure with preserved ejection fraction. We aimed at describing the parameters most often used, thresholds where possible, and correlation to echocardiographic and invasive measurements. Methods and results: A systematic literature review was performed using the databases of PubMed, Embase, and Cochrane. In total, 3808 articles were screened, and 102 studies were included. Four main CMR techniques were identified: tagging; time/volume curves; mitral inflow quantification with velocity-encoded phase-contrast sequences; and feature tracking. Techniques were described and estimates were presented in tables. From published studies, peak change of torsion shear angle versus volume changes in early diastole (−dφ′/dV′) (from tagging analysis), early peak filling rate indexed to LV end-diastolic volume <2.1 s−1 (from LV time-volume curve analysis), enlarged LA maximal volume >52 mL/m2, lowered LA total (<40%), and lowered LA passive emptying fractions (<16%) seem to be reliable measures of LV diastolic dysfunction. Feature tracking, especially of the atrium, shows promise but is still a novel technique. Conclusion: CMR techniques of LV untwisting and early filling and LA measures of poor emptying are promising for the diagnosis of LV filling impairment, but further research in long-term follow-up studies is needed to assess the ability for the parameters to predict patient related outcomes.
Relative Entropy in Determining Degressive Proportional Allocations
Authors: Cegiełka Katarzyna , Dniestrzański Piotr , Łyko Janusz , Maciuk Arkadiusz , Szczeciński Maciej
Published: July 2021

The principle of degressively proportional apportionment of goods, being a compromise between equality and proportionality, facilitates the application of many different allocation rules. Agents with smaller entitlements are more interested in an allocation that is as close to equality as possible, while those with greater entitlements prefer an allocation as close to proportionality as possible. Using relative entropy to quantify the inequity of allocation, this paper indicates an allocation that neutralizes these two contradictory approaches by symmetrizing the inequities perceived by the smallest and largest agents participating in the apportionment. First, based on some selected properties, the set of potential allocation rules was reduced to those generated by power functions. Then, the existence of the power function whose exponent is determined so as to generate the allocation that symmetrizes the relative entropy with respect to equal and proportional allocations was shown. As a result, all agents of the apportionment are more inclined to accept the proposed allocation regardless of the size of their entitlements. The exponent found in this way shows the significant relationship between the problem under study and the well-known Theil indices of inequality. The problem may also be seen from this viewpoint.
Performance Analysis and Optimization of a Series Heat Exchangers Organic Rankine Cycle Utilizing Multi-Heat Sources from a Marine Diesel Engine
Authors: Li Youyi , Tang Tianhao
Published: July 2021

Organic Rankine Cycle (ORC) is an effective way to recycle waste heat sources of a marine diesel engine. The aim of the present paper is to analyze and optimize the thermoeconomic performance of a Series Heat Exchangers ORC (SHEORC) for recovering energy from jacket water, scavenge air, and exhaust gas. The three sources are combined into three groups of jacket water (JW)→exhaust gas (EG), scavenge air (SA)→exhaust gas, and jacket water→scavenge air→exhaust gas. The influence of fluid mass flow rate, evaporation pressure, and heat source recovery proportion on the thermal performance and economic performance of SHEORC was studied. A single-objective optimization with power output as the objective and multi-objective optimization with exergy efficiency and levelized cost of energy (LCOE) as the objectives are carried out. The analysis results show that in jacket water→exhaust gas and jacket water→scavenge air→exhaust gas source combination, there is an optimal heat recovery proportion through which the SHEORC could obtain the best performance. The optimization results showed that R245ca has the best performance in thermoeconomic performance in all three source combinations. With scavenge air→exhaust, the power output, exergy efficiency, and LCOE are 354.19 kW, 59.02%, and 0.1150 $/kWh, respectively. Integrating the jacket water into the SA→EG group would not increase the power output, but would decrease the LCOE.
Multiobjective Optimization of Pin-Type Flow Channels Using a Reinterpretation of Murray’s Law
Authors: Vaz Warren Santiago
Published: July 2021

Biomimetics has been used to improve performance in several fields of engineering. For flow fields, Murray’s Law has been used to explore branching of channels that carry reactants and products. The applicability of Murray’s Law to flow fields was examined here. The pin-type flow field was used to explore variations and conflicting performance objectives: pressure drop, manufacturability, standard deviation of flow velocity, and channel area. NSGA-II was used to solve a multiobjective optimization problem. Two designs, 3 × 3 and 11 × 11, were analyzed. Results that were similar to previous single-objective studies were obtained, confirming the efficacy of Murray’s Law. Computational fluid dynamics simulations were used to compare optimized and unoptimized designs. The maximum velocity for the 3 × 3 and 11 × 11 cases was lower when Murray’s Law was followed, indicating that it effectively slowed down the flow. Similarly, the flow was much more uniform: the standard deviation of flow velocity in the channels was 94% and 57% lower, respectively, for both cases, compared to the unoptimized designed. Finally, a method to select one optimal solution from a front of non-dominated solutions, the nearest point method, was demonstrated.
Multilayer Model Predictive Control for a Voltage Mode Digital Power Amplifier
Authors: Wei Xinwei , Zhu Xiaonan , Zhang Wenyuan , Wang Hanzhe , Wang Hongliang , Luo An , Li Minying
Published: July 2021

The application of the finite control set model predictive control to cascaded inverters is severely limited by its computational complexity. In this paper, a load observer based multilayer model predictive control is proposed for the voltage mode digital power amplifier employing cascaded full-bridge neutral point clamped inverter, which can avoid the use of load current sensor and greatly reduce the controller computation without affecting its dynamic performance. The discrete mathematical model of the voltage mode digital power amplifier employing cascaded full-bridge neutral point clamped inverter is established with filter inductor current and filter capacitor voltage as state variables. A load current observer is designed based on this to avoid the use of load current observer. Based on the discrete model and the observed load current, the upper layer of the multilayer model predictive control determines the optimal level that minimizes the cost function. The middle layer allocates the optimal level to each submodule in order to achieve capacitor voltage balancing. The lower layer determines the switching state of each submodule in order to reduce switching actions. Finally, the experimental results based on the designed nine-level prototype show that the develop multilayer model predictive control lead to acceptable steady state, dynamic and robust performance, with only 1.37% of the run time of the traditional model predictive control.
Development of Air Conditioner Robot Prototype That Follows Humans in Outdoor Applications
Authors: Chaari Mohamed Zied , Abdelfatah Mohamed , Loreno Christopher , Al-Rahimi Rashid
Published: July 2021

According to Robert McSweeney, in light of a new study: “Conditions in the GCC could become so hot and humid in the coming years that staying outside for more than six hours will become difficult”. He is a climate analyst at CARBON BRIEF, a nonprofit temperature and climate analysis group. He also states that changes there can help give us an idea of what the rest of the world can expect if we do not reduce the emissions that pollute homes and factories. Because of the high temperatures in GCC countries, the effect of heat stress is very high there, which discourages shoppers and pedestrians from shopping in the open area due to the physical exertion and high risks faced by people and workers. Heat stress peaks in most Arab Gulf countries from 11:00 a.m. to 4:00 p.m. during the summer season. Heat stress is increasingly an obstacle to economic efficiency in these countries. This work designs and develops a robot that tracks shoppers and provides a cool stream of air directly around them during shopping in open areas to reduce the effect of heat stress. The robot enables us to cool the temperature around customers in the market to increase comfort. In this project, a robot was designed and manufactured to track a specific person and cool the air around him through a cool stream of air generated by the air conditioner installed inside the robot. We used a Raspberry Pi camera sensor to detect the target person and interact with a single-board computer (Raspberry Pi 3) to accomplish this design and the prototype. Raspberry Pi controls the air-conditioning robot to follow the movement of the target person. We used image processing to discover the target shopper, the control system, and then guide the bot. In the meantime, the robot must also bypass any potential obstacles that could prevent its movement and cause a collision. We made a highly efficient design that can synchronize between the software algorithm and the mechanical platform of the robot. This work is merely the combination of a cool stream of air and a robot that follows a human.
Early Dropout Prediction in MOOCs through Supervised Learning and Hyperparameter Optimization
Authors: Panagiotakopoulos Theodor , Kotsiantis Sotiris , Kostopoulos Georgios , Iatrellis Omiros , Kameas Achilles
Published: July 2021

Over recent years, massive open online courses (MOOCs) have gained increasing popularity in the field of online education. Students with different needs and learning specificities are able to attend a wide range of specialized online courses offered by universities and educational institutions. As a result, large amounts of data regarding students’ demographic characteristics, activity patterns, and learning performances are generated and stored in institutional repositories on a daily basis. Unfortunately, a key issue in MOOCs is low completion rates, which directly affect student success. Therefore, it is of utmost importance for educational institutions and faculty members to find more effective practices and reduce non-completer ratios. In this context, the main purpose of the present study is to employ a plethora of state-of-the-art supervised machine learning algorithms for predicting student dropout in a MOOC for smart city professionals at an early stage. The experimental results show that accuracy exceeds 96% based on data collected during the first week of the course, thus enabling effective intervention strategies and support actions.
Power Limit Control Strategy for Household Photovoltaic and Energy Storage Inverter
Authors: Xu Zhongyan , Tao Shengyu , Fan Hongtao , Sun Jie , Sun Yaojie
Published: July 2021

The increased installation capacity of grid-connected household photovoltaic (PV) systems has been witnessed worldwide, and the power grid is facing the challenges of overvoltage during peak power generation and limited frequency regulation performance. With the dual purpose of enhancing the power grid safety and improving the PV utilization rate, the maximum feed-in active power can be regulated by modifying the maximum power point tracking (MPPT) algorithm and battery energy storage (BES) accessibility as control instructions. However, the existing methods not only waste installed PV capacity, but it becomes no longer accessible when the state of charge (SOC) of the BES approaches its upper limit. In response to the above problem, this paper proposes a power limit control strategy to coordinate the MPPT algorithm and the BES accessibility. The proposed strategy directly controls the inverter output current according to the power limit instructions from the electric operation control centers, leading to a bus voltage difference. The difference serves as a control signal for BES and PV. Under a power-limiting scenario, priority is given to power regulation through energy storage to absorb the limited active power. When the SOC of the BES reaches the upper limit of charging, modification of the PV MPPT algorithm facilitates the inverter output power to meet the power limit requirements. To further verify the effectiveness of the proposed power limit control strategy, both simulation and experimental studies are conducted, which consistently indicated a synchronized inverter current with grid voltage and a rapid power response of the power-limiting instruction within 0.2 s. The power limit control strategy not only improves the PV energy utilization but also supports the safe and reliable operation of the power gird in the context of soaring renewable energy penetration.
Analysis of the Soft-Switching Tuning Effect on the Figures of Merit Involved in the Design of a Class-E Amplifier with Finite DC-Feed Inductance
Authors: Casallas Ingrid , Urbina Robert , Paez-Rueda Carlos-Ivan , Perilla Gabriel , Pérez Manuel , Fajardo Arturo
Published: July 2021

This paper explores the design of a Class-E amplifier with finite DC-feed inductance using three tuning methods. Furthermore, this work quantifies the impacts of the tuning process (referred to in this paper as the tuning effect) on the main figures of merit (FoMs) of this amplifier. The tuning goals were to guarantee two conditions: zero voltage and zero voltage derivative switching (i.e., soft-switching tuning). To the best of the authors’ knowledge, systematic tuning methods have not been analyzed before for this amplifier topology. Two of them are based on the iterative component tuning process, and they have been explored previously in the design of the conventional class-E amplifier with an RF choke inductance. The last tuning method explores the simultaneous adjustment of the control signal period and one amplifier capacitor. The analyzed tuning methods were validated by extensive simulations of case studies, which were designed following the power specifications of the Qi standard. In 100% and 96% of the case studies, zero voltage switching (ZVS) and zero-derivative voltage switching (ZDS) were achieved, respectively. Furthermore, we identified an unexpected behavior in the tuning process (referred to in this paper as the turning point), which consisted of a change of the expected trend of the soft-switching (i.e., ZVS and ZDS) point, and it occurred in 21% of the case studies. When this behavior occurred and converged to at least ZVS, the tuning process required more iterations and a large number of tuning variables. Additionally, after the tuning process, the total harmonic distortion and output power capacity were improved (i.e., in 78% and 61% of the case studies, respectively), whereas the output power, drain and added power efficiencies deteriorated (i.e., in 83%, 61% and 65% of the case studies, respectively) in the overall case studies. However, we could not identify an improvement in the overall FoMs related to the soft-switching tuning. Furthermore, the tuning impact was significant and produced some improvements and some deleterious effects for the FoMs in each case study, without a clear trend by FoMs or by tuning method. Therefore, the amplifier designer may choose the more favorable tuning method and the related FoM trade-offs for the required design specifications.
Low-Complexity Aggregation Techniques for DOA Estimation over Wide-RF Bandwidths
Authors: Mulinde Ronald , Kaushik Mayank , Attygalle Manik , Aziz Syed Mahfuzul
Published: July 2021

Accurate direction of arrival (DOA) estimation of wideband, low-power nonstationary signals is important in many radio frequency (RF) applications. This article analyses the performance of two incoherent aggregation techniques for the DOA estimation of high chirp-rate linear frequency modulated (LFM) signals used in modern radar and electronic warfare (EW) applications. The aim is to determine suitable aggregation techniques for blind DOA estimation for real-time implementation with a frequency channelised signal. The first technique calculates a single pseudospectrum by directly combining the spatial covariance matrices from each of the frequency bins. The second technique first calculates the spatial pseudospectra from the spatial covariance matrix (SCM) from each frequency bin and then combines the spatial pseudospectra into one single estimate. Firstly, for single and multiple signal emitters, we compare the DOA estimation performance of incoherent SCM-based aggregation with that of the incoherent spatial pseudospectra-based aggregation using the root mean-squared error (RMSE). Secondly, we determine the types of signals and conditions for which these incoherent aggregation techniques are more suited. We demonstrate that the low-complexity SCM-based aggregation technique can achieve relatively good estimation performance compared to the pseudospectra-based aggregation technique for multiple narrowband signal detection. However, pseudospectra aggregation is better suited for single wideband emitter detection. Both the incoherent aggregation techniques presented in this article offer a computational advantage over the coherent processing techniques and hence are better suited for real-time implementation.
Impedance Matching Method for 6.78 MHz Class-E2-Based WPT System
Authors: Zhang Yi , Feng Yue , Liu Sheng , Wu Jiande , He Xiangning
Published: July 2021

The performance of a conventional Class-E2-based WPT system is sensitive to system parameters such as the coil coupling coefficient and load variation. System efficiency decreases rapidly when the coil coupling coefficient and load deviate from their optimum values. In this paper, an impedance matching method and a design procedure are proposed to maintain high system efficiency over a wider range of coupling coefficient and load variations. The load-pull technique is adopted to identify the high-efficiency load region of a Class-E power amplifier (PA), and a double-L-type impedance matching network (IMN) is proposed to transform the load impedance of a Class-E PA into a high-efficiency working region. Compared to a single L-type IMN, a double-L-type IMN is more flexible and has better tuning performance. A 6.78 MHz Class-E2-based WPT system was built to validate the proposed design method. The experimental results show that the proposed double-L-type IMN can significantly attenuate the decline in Class-E PA efficiency when system parameters dynamically change. With a double-L-type IMN, the WPT system could maintain high efficiency (over 55%) under a wider range of coil coupling coefficient and load variations. The peak system efficiency reached 83.2% with 13.7 W output power. The impedance matching method and design procedure in this paper could provide a practical solution for building a high-efficiency WPT system with strong robustness.
Converter-Driven Stability Analysis of Power Systems Integrated with Hybrid Renewable Energy Sources
Authors: Luo Jianqiang , Zou Yiqing , Bu Siqi , Karaagac Ulas
Published: July 2021

Renewable energy sources such as wind power and photovoltaics (PVs) have been increasingly integrated into the power system through power electronic converters in recent years. However, power electronic converter-driven stability has issues under specific circumstances, for instance, modal resonances might deteriorate the dynamic performance of the power systems or even threaten the overall stability. In this work, the integration impact of a hybrid renewable energy source (HRES) system on modal interaction and converter-driven stability was investigated in an IEEE 16-machine 68-bus power system. In this paper, firstly, an HRES system is introduced, which consists of full converter-based wind power generation (FCWG) and full converter-based photovoltaic generation (FCPV). The equivalent dynamic models of FCWG and FCPV are then established, followed by linearized state-space modeling. On this basis, converter-driven stability analysis was performed to reveal the modal resonance mechanisms between different renewable energy sources (RESs) and weak grids in the interconnected power systems and the multi-modal interaction phenomenon. Additionally, time-domain simulations were conducted to verify the effectiveness of dynamic models and support the converter-driven stability analysis results. To avoid detrimental modal resonances, a multi-modal and multi-parametric optimization strategy is further proposed by retuning the controller parameters of the multi-RESs in the HRES system. The overall results demonstrate the modal interaction effect between the external AC power system and the HRES system and its various impacts on converter-driven stability.