bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrins: An Important Link between Angiogenesis, Inflammation and Eye Diseases
Authors: Mrugacz Małgorzata , Bryl Anna , Falkowski Mariusz , Zorena Katarzyna
Published: July 2021

Integrins belong to a group of cell adhesion molecules (CAMs) which is a large group of membrane-bound proteins. They are responsible for cell attachment to the extracellular matrix (ECM) and signal transduction from the ECM to the cells. Integrins take part in many other biological activities, such as extravasation, cell-to-cell adhesion, migration, cytokine activation and release, and act as receptors for some viruses, including severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). They play a pivotal role in cell proliferation, migration, apoptosis, tissue repair and are involved in the processes that are crucial to infection, inflammation and angiogenesis. Integrins have an important part in normal development and tissue homeostasis, and also in the development of pathological processes in the eye. This review presents the available evidence from human and animal research into integrin structure, classification, function and their role in inflammation, infection and angiogenesis in ocular diseases. Integrin receptors and ligands are clinically interesting and may be promising as new therapeutic targets in the treatment of some eye disorders.
Viscoelastic Properties in Cancer: From Cells to Spheroids
Authors: Abidine Yara , Giannetti Arianna , Revilloud Jean , Laurent Valérie M. , Verdier Claude
Published: July 2021

AFM-based rheology methods enable the investigation of the viscoelastic properties of cancer cells. Such properties are known to be essential for cell functions, especially for malignant cells. Here, the relevance of the force modulation method was investigated to characterize the viscoelasticity of bladder cancer cells of various invasiveness on soft substrates, revealing that the rheology parameters are a signature of malignancy. Furthermore, the collagen microenvironment affects the viscoelastic moduli of cancer cell spheroids; thus, collagen serves as a powerful proxy, leading to an increase of the dynamic moduli vs. frequency, as predicted by a double power law model. Taken together, these results shed new light on how cancer cells and tissues adapt their viscoelastic properties depending on their malignancy and the microenvironment. This method could be an attractive way to control their properties in the future, based on the similarity of spheroids with in vivo tumor models.
Deficiency in MT5-MMP Supports Branching of Human iPSCs-Derived Neurons and Reduces Expression of GLAST/S100 in iPSCs-Derived Astrocytes
Authors: Arnst Nikita , Belio-Mairal Pedro , García-González Laura , Arnaud Laurie , Greetham Louise , Nivet Emmanuel , Rivera Santiago , Dityatev Alexander
Published: July 2021

For some time, it has been accepted that the β-site APP cleaving enzyme 1 (BACE1) and the γ-secretase are two main players in the amyloidogenic processing of the β-amyloid precursor protein (APP). Recently, the membrane-type 5 matrix metalloproteinase (MT5-MMP/MMP-24), mainly expressed in the nervous system, has been highlighted as a new key player in APP-processing, able to stimulate amyloidogenesis and also to generate a neurotoxic APP derivative. In addition, the loss of MT5-MMP has been demonstrated to abrogate pathological hallmarks in a mouse model of Alzheimer’s disease (AD), thus shedding light on MT5-MMP as an attractive new therapeutic target. However, a more comprehensive analysis of the role of MT5-MMP is necessary to evaluate how its targeting affects neurons and glia in pathological and physiological situations. In this study, leveraging on CRISPR-Cas9 genome editing strategy, we established cultures of human-induced pluripotent stem cells (hiPSC)-derived neurons and astrocytes to investigate the impact of MT5-MMP deficiency on their phenotypes. We found that MT5-MMP-deficient neurons exhibited an increased number of primary and secondary neurites, as compared to isogenic hiPSC-derived neurons. Moreover, MT5-MMP-deficient astrocytes displayed higher surface area and volume compared to control astrocytes. The MT5-MMP-deficient astrocytes also exhibited decreased GLAST and S100β expression. These findings provide novel insights into the physiological role of MT5-MMP in human neurons and astrocytes, suggesting that therapeutic strategies targeting MT5-MMP should be controlled for potential side effects on astrocytic physiology and neuronal morphology.
Review: Vaspin (SERPINA12) Expression and Function in Endocrine Cells
Authors: Kurowska Patrycja , Mlyczyńska Ewa , Dawid Monika , Jurek Małgorzata , Klimczyk Dominika , Dupont Joelle , Rak Agnieszka
Published: July 2021

Proper functioning of the body depends on hormonal homeostasis. White adipose tissue is now known as an endocrine organ due to the secretion of multiple molecules called adipokines. These proteins exert direct effects on whole body functions, including lipid metabolism, angiogenesis, inflammation, and reproduction, whereas changes in their level are linked with pathological events, such as infertility, diabetes, and increased food intake. Vaspin-visceral adipose tissue-derived serine protease inhibitor, or SERPINA12 according to serpin nomenclature, is an adipokine discovered in 2005 that is connected to the development of insulin resistance, obesity, and inflammation. A significantly higher amount of vaspin was observed in obese patients. The objective of this review was to summarize the latest findings about vaspin expression and action in endocrine tissues, such as the hypothalamus, pituitary gland, adipose tissue, thyroid, ovary, placenta, and testis, as well as discuss the link between vaspin and pathologies connected with hormonal imbalance.
Translation Initiation Regulated by RNA-Binding Protein in Mammals: The Modulation of Translation Initiation Complex by Trans-Acting Factors
Authors: Fukao Akira , Tomohiro Takumi , Fujiwara Toshinobu
Published: July 2021

Protein synthesis is tightly regulated at each step of translation. In particular, the formation of the basic cap-binding complex, eukaryotic initiation factor 4F (eIF4F) complex, on the 5′ cap structure of mRNA is positioned as the rate-limiting step, and various cis-elements on mRNA contribute to fine-tune spatiotemporal protein expression. The cis-element on mRNAs is recognized and bound to the trans-acting factors, which enable the regulation of the translation rate or mRNA stability. In this review, we focus on the molecular mechanism of how the assembly of the eIF4F complex is regulated on the cap structure of mRNAs. We also summarize the fine-tuned regulation of translation initiation by various trans-acting factors through cis-elements on mRNAs.
Brain Protection after Anoxic Brain Injury: Is Lactate Supplementation Helpful?
Authors: Annoni Filippo , Peluso Lorenzo , Gouvêa Bogossian Elisa , Creteur Jacques , Zanier Elisa R. , Taccone Fabio Silvio
Published: July 2021

While sudden loss of perfusion is responsible for ischemia, failure to supply the required amount of oxygen to the tissues is defined as hypoxia. Among several pathological conditions that can impair brain perfusion and oxygenation, cardiocirculatory arrest is characterized by a complete loss of perfusion to the brain, determining a whole brain ischemic-anoxic injury. Differently from other threatening situations of reduced cerebral perfusion, i.e., caused by increased intracranial pressure or circulatory shock, resuscitated patients after a cardiac arrest experience a sudden restoration of cerebral blood flow and are exposed to a massive reperfusion injury, which could significantly alter cellular metabolism. Current evidence suggests that cell populations in the central nervous system might use alternative metabolic pathways to glucose and that neurons may rely on a lactate-centered metabolism. Indeed, lactate does not require adenosine triphosphate (ATP) to be oxidated and it could therefore serve as an alternative substrate in condition of depleted energy reserves, i.e., reperfusion injury, even in presence of adequate tissue oxygen delivery. Lactate enriched solutions were studied in recent years in healthy subjects, acute heart failure, and severe traumatic brain injured patients, showing possible benefits that extend beyond the role as alternative energetic substrates. In this manuscript, we addressed some key aspects of the cellular metabolic derangements occurring after cerebral ischemia-reperfusion injury and examined the possible rationale for the administration of lactate enriched solutions in resuscitated patients after cardiac arrest.
Sniff Species: SURMOF-Based Sensor Array Discriminates Aromatic Plants beyond the Genus Level
Authors: Okur Salih , Li Chun , Zhang Zejun , Vaidurya Pratap Sahi , Sarheed Mohammed , Kanbar Adnan , Franke Leonard , Geislhöringer Felix , Heinke Lars , Lemmer Uli , Nick Peter , Wöll Christof
Published: July 2021

Lamiaceae belong to the species-richest family of flowering plants and harbor many species that are used as herbs or in medicinal applications such as basils or mints. The evolution of this group has been driven by chemical speciation, mainly volatile organic compounds (VOCs). The commercial use of these plants is characterized by adulteration and surrogation to a large extent. Authenticating and discerning this species is thus relevant for consumer safety but usually requires cumbersome analytics, such as gas chromatography, often coupled with mass spectroscopy. Here, we demonstrate that quartz-crystal microbalance (QCM)-based electronic noses provide a very cost-efficient alternative, allowing for fast, automated discrimination of scents emitted from the leaves of different plants. To explore the range of this strategy, we used leaf material from four genera of Lamiaceae along with lemongrass, which is similarly scented but from an unrelated outgroup. To differentiate the scents from different plants unambiguously, the output of the six different SURMOF/QCM sensors was analyzed using machine learning (ML) methods together with a thorough statistical analysis. The exposure and purging of data sets (four cycles) obtained from a QCM-based, low-cost homemade portable e-Nose were analyzed using a linear discriminant analysis (LDA) classification model. Prediction accuracy with repeated test measurements reached values of up to 0%. We show that it is possible not only to discern and identify plants at the genus level but also to discriminate closely related sister clades within a genus (basil), demonstrating that an e-Nose is a powerful device that can safeguard consumer safety against dangers posed by globalized trade.
Mouse and Fly Sperm Motility Changes Differently under Modelling Microgravity
Authors: Ogneva Irina V.
Published: July 2021

Sperm motility is essential for the natural fertilization process in most animal species. Despite the fact that evolution took place under conditions of constant gravity, the motility of spermatozoa of insects and mammals under microgravity conditions changes in different ways. In this work, an attempt was made to explain this effect. The sperm motility of the fruit fly Drosophila melanogaster and the mouse was evaluated after exposure to a random positioning machine for 6 h. Sodium fluoride was used to inhibit serine/threonine phosphatases, sodium orthovanadate was used to inhibit tyrosine phosphatases, and 6-(dimethylamino)purine was used to inhibit protein kinases. The results obtained indicate that simulated microgravity leads to an increase in the speed of movement of fly spermatozoa by 30% (p < 0.05), and this effect is blocked by sodium fluoride. In contrast, a 29% (p < 0.05) decrease in the speed of movement of mouse spermatozoa under simulated microgravity is prevented by 6-(dimethylamino)purine. Moreover, after 6 h of exposure, the content of tubulin cytoskeleton and actin proteins remains at the control level in the spermatozoa of flies and mice. However, the content of the actin-binding protein alpha-actinin in fly sperm decreases by 29% (p < 0.05), while in mouse sperm, the relative content of alpha-actinin1 increases by 94% (p < 0.05) and alpha-actinin4 by 121% (p < 0.05) relative to the control, as determined by 6 simulated microgravity tests. It can be assumed that the effect of simulated microgravity on the motility of mammalian spermatozoa is mediated through the regulation of phosphorylation and that of insects through the regulation of dephosphorylation of motor proteins; moreover, the development of a response to changes in external mechanical conditions has a different time scale.
Sensitivity of Winter Barley Yield to Climate Variability in a Pleistocene Loess Area
Authors: Heil Kurt , Gerl Sebastian , Schmidhalter Urs
Published: July 2021

Global climate change is predicted to increase temperatures and change the distribution of precipitation. However, there is high uncertainty regarding the regional occurrence and intensity of climate change. Therefore, this work examines the effects of climate parameters on the long-term yields of winter barley and assesses the parameters affecting plant development throughout the year and in specific growth phases. The investigation was carried out in an area with Pleistocene loess, a highly fertile site in Germany. The effect of climate on crop yields was modeled with monthly weather parameters and additional indices such as different drought parameters, heat-related stress, late spring frost, early autumn frost, and precipitation-free periods. Residuals and yield values were treated as dependent variables. The residuals were determined from long-term yield trends using the autoregressive integrated moving average (ARIMA) method. The results indicated that temperature and precipitation are significant in all calculations in all variants, but to a lesser degree when considered as sums or mean values, compared with specific indices (e.g., frost-alternating days, the temperature threshold, the precipitation intensity, rain-free days, the early/late frost index, and the de Martonne–Reichel dryness index). The inter-annual variations in crop yields were mainly determined by the prevailing climatic conditions in winter as well as the transition periods from the warmer season to winter and vice versa. The main winter indices were the temperature threshold, frost-alternating days, and precipitation intensity. During the main growth periods, only the precipitation intensity was significant. These findings can be attributed to the high available field water capacity of this site, which overcomes the need for summer precipitation if the soil water storage is replenished during winter.
Preparation and Characterization of Functional Films Based on Chitosan and Corn Starch Incorporated Tea Polyphenols
Authors: Gao Lepeng , Zhu Tao , He Fuyang , Ou Zhiqiang , Xu Jian , Ren Lili
Published: July 2021

The functional films based on chitosan and corn starch incorporated tea polyphenols were developed through mixing the chitosan and starch solution and the powder of tea polyphenols by the casting method. The objective of this research was to investigate the effect of different concentrations of tea polyphenols on the functional properties of the films. Attenuated total reflectance Fourier transform infrared spectrometry and X-ray diffraction were used to investigate the potential interactions among chitosan, corn starch and tea polyphenols in the blend films. Physical properties of the blend films, including density, moisture content, opacity, color, water solubility and water swelling, as well as morphological characteristics, were measured. The results demonstrated that the incorporation of tea polyphenols caused the blend films to lead to a darker appearance. The water solubility of the blend film increased with the increase of tea polyphenol concentrations, while moisture content and swelling degree decreased. The hydrogen bonding between chitosan, starch and tea polyphenols restricted the movement of molecular chains and was helpful to the stability of the blend films. The results suggested that these biodegradable blend films could potentially be used as packaging films for the food and drug industries to extend the shelf life to maintain their quality and safety.
A Study on Beryl in the Cuonadong Be-W-Sn Polymetallic Deposit, Longzi County, Tibet, China
Authors: Shen Jia-Qi , Hu Zhi-Kang , Cui Shi-Yuan , Zhang Yu-Fei , Li En-Qi , Liang Wei , Xu Bo
Published: July 2021

Recently, aquamarine was discovered in the Cuonadong Be-W-Sn Polymetallic Deposit, Longzi County, Tibet. Longzi aquamarine is being extracted and is expected to be available over the next decade. This study provides a full set of data through standard gemmological properties, including scenes, color characteristics and advanced spectroscopic and chemical analyses, including micro ultraviolet–visible–near-infrared (UV–Vis–NIR), Raman and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The main inclusions in Longzi aquamarine are gas–liquid inclusions and a great number of quartz inclusions. The content of type I H2O is greater than that of type II H2O because of the low-alkali metal content, and “tetrahedral” substitutions and “octahedral” substitutions exist at the same time.
Photoconduction of Polar and Nonpolar Cuts of Undoped Sr0.61Ba0.39Nb2O6 Single Crystals
Authors: Beyreuther Elke , Ratzenberger Julius , Roeper Matthias , Kirbus Benjamin , Rüsing Michael , Ivleva Liudmila I. , Eng Lukas M.
Published: July 2021

In the last two decades, variably doped strontium barium niobate (SBN) has attracted a lot of scientific interest mainly due to its specific non-linear optical response. Comparably, the parental compound, i.e., undoped SBN, appears to be less studied so far. Here, two different cuts of single-crystalline nominally pure strontium barium niobate in the composition Sr0.61Ba0.39Nb2O6 (SBN61) are comprehensively studied and analyzed with regard to their photoconductive responses. We present conductance measurements under systematically varied illumination conditions along either the polar z-axis or perpendicular to it (x-cut). Apart from a pronounced photoconductance (PC) already under daylight and a large effect upon super-bandgap illumination in general, we observe (i) distinct spectral features when sweeping the excitation wavelength over the sub-bandgap region as then discussed in the context of deep and shallow trap states, (ii) extremely slow long-term relaxation for both light-on and light-off transients in the range of hours and days, (iii) a critical dependence of the photoresponse on the pre-illumination history of the sample, and (iv) a current–voltage hysteresis depending on both the illumination and the electrical-measurement conditions in a complex manner.
X-ray Diffraction of Alkali-Activated Materials with Cement By-Pass Dust
Authors: Vojvodíková Barbara , Procházka Lukáš , Boháčová Jana
Published: July 2021

Alkali-activated materials are alternative building binders, where secondary raw materials are processed. The possibility of using landfilled waste materials in the building industry increases their potential application in construction practice, and they are therefore subject to extensive research, especially in recent years. This paper briefly summarizes the interesting results of an experiment aimed at verifying the possibility of applying cement by-pass dust (CBPD) in the preparation of alkali-activated materials. The research was focused on the possibilities of using these wastes for the preparation of small elements of garden architecture. This work also briefly summarized the interesting results of an experiment aimed at verifying the possibility of applying cement by-pass dust (CBPD) in the preparation of alkali-activated materials. In the experiment, a mixture of blast furnace granulated slag, fly ash and cement by-pass dust was alkali activated with sodium metasilicate.
The Sharing of the Same Host of Two Species of Anemonefish in the Gulf of Thailand, One of Which Is Possibly Introduced
Authors: Songploy Se , Chavanich Suchana , Mariasingarayan Yosuva , Viyakarn Voranop
Published: July 2021

At Samaesan Island, which is in Chon Buri Province, the Upper Gulf of Thailand, in 2018 we found skunk anemonefish (Amphiprion akallopisos) previously only known from the Andaman Sea that have been establishing their populations in the area at a 4-m depth [...]
Automated Skin Lesion Classification on Ultrasound Images
Authors: Marosán-Vilimszky  Péter , Szalai  Klára , Horváth  András , Csabai  Domonkos , Füzesi  Krisztián , Csány  Gergely , Gyöngy  Miklós
Published: July 2021

The growing incidence of skin cancer makes computer-aided diagnosis tools for this group of diseases increasingly important. The use of ultrasound has the potential to complement information from optical dermoscopy. The current work presents a fully automatic classification framework utilizing fully-automated (FA) segmentation and compares it with classification using two semi-automated (SA) segmentation methods. Ultrasound recordings were taken from a total of 310 lesions (70 melanoma, 130 basal cell carcinoma and 110 benign nevi). A support vector machine (SVM) model was trained on 62 features, with ten-fold cross-validation. Six classification tasks were considered, namely all the possible permutations of one class versus one or two remaining classes. The receiver operating characteristic (ROC) area under the curve (AUC) as well as the accuracy (ACC) were measured. The best classification was obtained for the classification of nevi from cancerous lesions (melanoma, basal cell carcinoma), with AUCs of over 90% and ACCs of over 85% obtained with all segmentation methods. Previous works have either not implemented FA ultrasound-based skin cancer classification (making diagnosis more lengthy and operator-dependent), or are unclear in their classification results. Furthermore, the current work is the first to assess the effect of implementing FA instead of SA classification, with FA classification never degrading performance (in terms of AUC or ACC) by more than 5%.
Radiation Dose Reduction in CT Torsion Measurement of the Lower Limb: Introduction of a New Ultra-Low Dose Protocol
Authors: Keller Gabriel , Götz Simon , Kraus Mareen Sarah , Grünwald Leonard , Springer Fabian , Afat Saif
Published: July 2021

This study analyzed the radiation exposure of a new ultra-low dose (ULD) protocol compared to a high-quality (HQ) protocol for CT-torsion measurement of the lower limb. The analyzed patients (n = 60) were examined in the period March to October 2019. In total, 30 consecutive patients were examined with the HQ and 30 consecutive patients with the new ULD protocol comprising automatic tube voltage selection, automatic exposure control, and iterative image reconstruction algorithms. Radiation dose parameters as well as the contrast-to-noise ratio (CNR) and diagnostic confidence (DC; rated by two radiologists) were analyzed and potential predictor variables, such as body mass index and body volume, were assessed. The new ULD protocol resulted in significantly lower radiation dose parameters, with a reduction of the median total dose equivalent to 0.17 mSv in the ULD protocol compared to 4.37 mSv in the HQ protocol (p < 0.001). Both groups showed no significant differences in regard to other parameters (p = 0.344–0.923). CNR was 12.2% lower using the new ULD protocol (p = 0.033). DC was rated best by both readers in every HQ CT and in every ULD CT. The new ULD protocol for CT-torsion measurement of the lower limb resulted in a 96% decrease of radiation exposure down to the level of a single pelvic radiograph while maintaining good image quality.
Prognostic Value of CTA-Derived Left Ventricular Mass in Neonates with Congenital Heart Disease
Authors: Ellmann Stephan , Nickel Julie-Marie , Heiss Rafael , El Amrani Nouhayla , Wüst Wolfgang , Rompel Oliver , Rueffer Andre , Cesnjevar Robert , Dittrich Sven , Uder Michael , May Matthias S.
Published: July 2021

For therapeutic decisions regarding uni- or biventricular surgical repair in congenital heart disease (CHD), left ventricular mass (LVM) is an important factor. The aim of this retrospective study was to determine the LVM of infants with CHD in thoracic computed tomography angiographies (CTAs) and to evaluate its usefulness as a prognostic parameter, with special attention paid to hypoplastic left heart (HLH) patients. Manual segmentation of the left ventricular endo- and epicardial volumes was performed in CTAs of 132 infants. LVMs were determined from these volumes and normalized to body surface area. LVMs of patients with different types of CHD were compared to each other using analyses of variances (ANOVA). An LVM cutoff for discrimination between uni- and biventricular repair was determined using receiver operating characteristics. Survival rates were calculated using Kaplan–Meier statistics. Patients with a clinical diagnosis of an HLH had significantly lower mean LVM (21.88 g/m2) compared to patients without applicable disease (50.22 g/m2; p < 0.0001) and compared to other CHDs, including persistent truncus arteriosus, left ventricular outflow tract obstruction, transposition of the great arteries, pulmonary artery stenosis or atresia, and double-outlet right ventricle (all, p < 0.05). The LVM cutoff for uni- vs. biventricular surgery was 33.9 g/m2 (sensitivity: 82.3%; specificity: 73.7%; PPV: 94.9%). In a subanalysis of HLH patients, a sensitivity of 50.0%, specificity of 100%, PPV of 100%, and NPV of 83.3% was determined. Patient survival was not significantly different between the surgical approaches or between patients with LVM above or below the cutoff. LVM can be measured in chest CTA of newborns with CHD and can be used as a prognostic factor.
Mild Clinical Presentation of Joubert Syndrome in a Male Adult Carrying Biallelic MKS1 Truncating Variants
Authors: Brunetti-Pierri Raffaella , Karali Marianthi , Testa Francesco , Cappuccio Gerarda , Onore Maria Elena , Romano Francesca , De Rosa Giuseppe , Tedeschi Enrico , Brunetti-Pierri Nicola , Banfi Sandro , Simonelli Francesca
Published: July 2021

Pathogenic variants in the MKS1 gene are responsible for a ciliopathy with a wide spectrum of clinical manifestations ranging from Meckel and Joubert syndrome (JBTS) to Bardet-Biedl syndrome, and involving the central nervous system, liver, kidney, skeleton, and retina. We report a 39-year-old male individual presenting with isolated Retinitis Pigmentosa (RP), as assessed by full ophthalmological evaluation including Best-Corrected Visual Acuity measurements, fundus examination, Goldmann Visual Field test, and full-field Electroretinography. A clinical exome identified biallelic nonsense variants in MKS1 that prompted post-genotyping investigations for systemic abnormalities of ciliopathy. Brain magnetic resonance imaging revealed malformations of the posterior cranial fossa with the ‘molar tooth sign’ and cerebellar folia dysplasia, which are both distinctive features of JBTS. No other organ or skeletal abnormalities were detected. This case illustrates the power of clinical exome for the identification of the mildest forms of a disease spectrum, such as a mild JBTS with RP in the presented case of an individual carrying biallelic truncating variants in MKS1.
Effect of Water Storage on Hardness and Interfacial Strength of Resin Composite Luting Agents Bonded to Surface-Treated Monolithic Zirconia
Authors: Tzanakakis Emmanouil-George , Dimitriadi Maria , Tzoutzas Ioannis , Koidis Petros , Zinelis Spiros , Eliades George
Published: July 2021

Background: Durable bonding between resin composite luting agents (CLA) and zirconia is still a matter of controversy. The purpose of this study was to evaluate the effect of water storage on hardness and interfacial strength of three CLA, a non-adhesive (Multilink Automix/ML), an adhesive (Panavia F 2.0/PF) and a self-adhesive (PermaCem 2.0/PC), bonded to polished (CL) and grit-blasted (AL: 50 μm alumina, SJ: Sil-Jet + Monobond Plus silane) monolithic zirconia surfaces. Methods: CLA specimens (n = 5/cement, condition) were prepared, stored under dry conditions or immersed in water, and Vickers hardness (VH) measurements were obtained at 1 h, 24 h, 1 week and 3 weeks intervals. Optical profilometry was used to determine the roughness parameters (Sa, Sz, Sdr, Sci) of zirconia surfaces (n = 5/treatment). A shear strength test (SBS, n = 10 × 2/cement) was performed to assess the strength and fractography of the cements bonded to zirconia after isothermal water storage and thermal-cycling (TC). Results: PF demonstrated significantly lower VHN after water storage at all time intervals, PC at 1 w, 3 w and ML at 3 w. SJ and AL showed significantly higher values from CL in all roughness parameters. Weibull analysis revealed the following significance in σο ranking within the same material: AL, SJ, ALTC > SJTC, CL > CLTC (PF); SJ, SJTC, AL, ALTC > CL, CLTC (PC) and SJ, SJTC > AL > ALTC > CL, CLTC (ML). Within the same surface treatment subgroups, the significance in σo ranking was PC, ML > PF (before/after TC) for SJ; PC > PF > ML (before TC), PC, PF > ML (after TC) for AL, and PC > PF > ML (before/after TC) for CL. For the m ranking, the only significant difference within each material group was found in PC (AL > ALTC) and for the same surface treatment in AL (PC > ML). Conclusion: There are significant differences in the water plasticization susceptibility of the CLA tested; the materials with adhesive monomers were the most affected. Tribo-chemical silica coating combined with a silane coupling agent was the most efficient bonding treatment for the non-adhesive and the self-adhesive materials. The adhesive CLA performed better on alumina-blasted than on tribo-chemically coated surfaces.
Geometric Variational Inference
Authors: Frank Philipp , Leike Reimar , Enßlin Torsten A.
Published: July 2021

Efficiently accessing the information contained in non-linear and high dimensional probability distributions remains a core challenge in modern statistics. Traditionally, estimators that go beyond point estimates are either categorized as Variational Inference (VI) or Markov-Chain Monte-Carlo (MCMC) techniques. While MCMC methods that utilize the geometric properties of continuous probability distributions to increase their efficiency have been proposed, VI methods rarely use the geometry. This work aims to fill this gap and proposes geometric Variational Inference (geoVI), a method based on Riemannian geometry and the Fisher information metric. It is used to construct a coordinate transformation that relates the Riemannian manifold associated with the metric to Euclidean space. The distribution, expressed in the coordinate system induced by the transformation, takes a particularly simple form that allows for an accurate variational approximation by a normal distribution. Furthermore, the algorithmic structure allows for an efficient implementation of geoVI which is demonstrated on multiple examples, ranging from low-dimensional illustrative ones to non-linear, hierarchical Bayesian inverse problems in thousands of dimensions.
The Electrochemical Stability of Starch Carbon as an Important Property in the Construction of a Lithium-Ion Cell
Authors: Kurc Beata , Pigłowska Marita , Rymaniak Łukasz
Published: July 2021

This paper shows use of starch-based carbon (CSC) and graphene as the anode electrode for lithium-ion cell. To describe electrochemical stability of the half-cell system and kinetic parameters of charging process in different temperatures, electrochemical impedance spectroscopy (EIS) measurement was adopted. It has been shown that smaller resistances are observed for CSC. Additionally, Bode plots show high electrochemical stability at higher temperatures. The activation energy for the SEI (solid–electrolyte interface) layer, charge transfer, and electrolyte were in the ranges of 24.06–25.33, 68.18–118.55, and 13.84–15.22 kJ mol−1, respectively. Moreover, the activation energy of most processes is smaller for CSC, which means that this electrode could serve as an eco-friendly biodegradable lithium-ion cell element.
Optimal Placement and Sizing of an Energy Storage System Using a Power Sensitivity Analysis in a Practical Stand-Alone Microgrid
Authors: Kim Dongmin , Yoon Kipo , Lee Soo Hyoung , Park Jung-Wook
Published: July 2021

The energy storage system (ESS) is developing into a very important element for the stable operation of power systems. An ESS is characterized by rapid control, free charging, and discharging. Because of these characteristics, it can efficiently respond to sudden events that affect the power system and can help to resolve congested lines caused by the excessive output of distributed generators (DGs) using renewable energy sources (RESs). In order to efficiently and economically install new ESSs in the power system, the following two factors must be considered: the optimal installation placements and the optimal sizes of ESSs. Many studies have explored the optimal installation placement and the sizing of ESSs by using analytical approaches, mathematical optimization techniques, and artificial intelligence. This paper presents an algorithm to determine the optimal installation placement and sizing of ESSs for a virtual multi-slack (VMS) operation based on a power sensitivity analysis in a stand-alone microgrid. Through the proposed algorithm, the optimal installation placement can be determined by a simple calculation based on a power sensitivity matrix, and the optimal sizing of the ESS for the determined placement can be obtained at the same time. The algorithm is verified through several case studies in a stand-alone microgrid based on practical power system data. The results of the proposed algorithm show that installing ESSs in the optimal placement could improve the voltage stability of the microgrid. The sizing of the newly installed ESS was also properly determined.
GaN-Based PCSS with High Breakdown Fields
Authors: Gaddy Matthew , Kuryatkov Vladimir , Wilson Nicholas , Neuber Andreas , Ness Richard , Nikishin Sergey
Published: July 2021

The suitability of GaN PCSSs (photoconductive semiconductor switches) as high voltage switches (>50 kV) was studied using a variety of commercially available semi-insulating GaN wafers as the base material. Analysis revealed that the wafers’ physical properties were noticeably diverse, mainly depending on the producer. High Voltage PCSSs were fabricated in both vertical and lateral geometry with various contacts, ohmic (Ti/Al/Ni/Au or Ni/Au), with and without a conductive n-GaN or p-type layer grown by metal-organic chemical vapor deposition. Inductively coupled plasma (ICP) reactive ion etching (RIE) was used to form a mesa structure to reduce field enhancements allowing for a higher field to be applied before electrical breakdown. The length of the active region was also varied from a 3 mm gap spacing to a 600 µm gap spacing. The shorter gap spacing supports higher electric fields since the number of macro defects within the device’s active region is reduced. Such defects are common in hydride vapor phase epitaxy grown samples and are likely one of the chief causes for electrical breakdown at field levels below the bulk breakdown field of GaN. Finally, the switching behavior of PCSS devices was tested using a pulsed, high voltage testbed and triggered by an Nd:YAG laser. The best GaN PCSS fabricated using a 600 µm gap spacing, and a mesa structure demonstrated a breakdown field strength as high as ~260 kV/cm.
An Informative Path Planner for a Swarm of ASVs Based on an Enhanced PSO with Gaussian Surrogate Model Components Intended for Water Monitoring Applications
Authors: Kathen Micaela Jara Ten , Flores Isabel Jurado , Reina Daniel Gutiérrez
Published: July 2021

Controlling the water quality of water supplies has always been a critical challenge, and water resource monitoring has become a need in recent years. Manual monitoring is not recommended in the case of large water surfaces for a variety of reasons, including expense and time consumption. In the last few years, researchers have proposed the use of autonomous vehicles for monitoring tasks. Fleets or swarms of vehicles can be deployed to conduct water resource explorations by using path planning techniques to guide the movements of each vehicle. The main idea of this work is the development of a monitoring system for Ypacarai Lake, where a fleet of autonomous surface vehicles will be guided by an improved particle swarm optimization based on the Gaussian process as a surrogate model. The purpose of using the surrogate model is to model water quality parameter behavior and to guide the movements of the vehicles toward areas where samples have not yet been collected; these areas are considered areas with high uncertainty or unexplored areas and areas with high contamination levels of the lake. The results show that the proposed approach, namely the enhanced GP-based PSO, balances appropriately the exploration and exploitation of the surface of Ypacarai Lake. In addition, the proposed approach has been compared with other techniques like the original particle swarm optimization and the particle swarm optimization with Gaussian process uncertainty component in a simulated Ypacarai Lake environment. The obtained results demonstrate the superiority of the proposed enhanced GP-based PSO in terms of mean square error with respect to the other techniques.
Review on Free-Space Optical Communications for Delay and Disruption Tolerant Networks
Authors: Goncalves Teixeira Mafalda , Molina Julio Ramirez , Soares Vasco N. G. J.
Published: July 2021

The increase of data-rates that are provided by free-space optical (FSO) communications is essential in our data-driven society. When used in satellite and interplanetary networks, these optical links can ensure fast connections, yet they are susceptible to atmospheric disruptions and long orbital delays. The Delay and Disruption Tolerant Networking (DTN) architecture ensures a reliable connection between two end nodes, without the need for a direct connection. This can be an asset when used with FSO links, providing protocols that can handle the intermittent nature of the connection. This paper provides a review on the theoretical and state-of-the-art studies on FSO and DTN. The aim of this review is to provide motivation for the research of an optical wireless satellite network, with focus on the use of the Licklider Transmission Protocol. The assessment presented establishes the viability of these networks, providing many examples to rely on, and summarizing the most recent stage of the development of the technologies addressed.
Sensory Substitution for the Visually Impaired: A Study on the Usability of the Sound of Vision System in Outdoor Environments
Authors: Zvorișteanu Otilia , Caraiman Simona , Lupu Robert-Gabriel , Botezatu Nicolae Alexandru , Burlacu Adrian
Published: July 2021

For most visually impaired people, simple tasks such as understanding the environment or moving safely around it represent huge challenges. The Sound of Vision system was designed as a sensory substitution device, based on computer vision techniques, that encodes any environment in a naturalistic representation through audio and haptic feedback. The present paper presents a study on the usability of this system for visually impaired people in relevant environments. The aim of the study is to assess how well the system is able to help the perception and mobility of the visually impaired participants in real life environments and circumstances. The testing scenarios were devised to allow the assessment of the added value of the Sound of Vision system compared to traditional assistive instruments, such as the white cane. Various data were collected during the tests to allow for a better evaluation of the performance: system configuration, completion times, electro-dermal activity, video footage, user feedback. With minimal training, the system could be successfully used in outdoor environments to perform various perception and mobility tasks. The benefit of the Sound of Vision device compared to the white cane was confirmed by the participants and by the evaluation results to consist in: providing early feedback about static and dynamic objects, providing feedback about elevated objects, walls, negative obstacles (e.g., holes in the ground) and signs.
Heat Transfer Efficiency Prediction of Coal-Fired Power Plant Boiler Based on CEEMDAN-NAR Considering Ash Fouling
Authors: Shi Yuanhao , Li Mengwei , Wen Jie , Yang Yanru , Cui Fangshu , Zeng Jianchao
Published: July 2021

Ash fouling has been an important factor in reducing the heat transfer efficiency and safety of the coal-fired power plant boilers. Scientific and accurate prediction of ash fouling of heat transfer surfaces is the basis of formulating a reasonable soot blowing strategy to improve energy efficiency. This study presented a comprehensive approach of dynamic prediction of the ash fouling of heat transfer surfaces in coal-fired power plant boilers. At first, the cleanliness factor is used to reflect the fouling level of the heat transfer surfaces. Then, a dynamic model is proposed to predict ash deposits in the coal-fired boilers by combining complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and nonlinear autoregressive neural networks (NARNN). To construct a reasonable network model, the minimum information criterion and trial-and-error method are used to determine the delay orders and hidden layers. Finally, the experimental object is established on the 300 MV economizer clearness factor dataset of the power station, and the root mean square error and mean absolute percentage error of the proposed method are the smallest. In addition, the experimental results show that this multiscale prediction model is more competitive than the Elman model.
Losing the Energy to Cook: An Exploration of Modern Food Systems and Energy Consumption in Domestic Kitchens
Authors: Scott Nigel , Barnard-Tallier Melinda , Batchelor Simon
Published: July 2021

The Modern Energy Cooking Services (MECS) programme has generated data on the amount of energy required to cook meals using different fuels and cooking devices. Fuel stacking is commonplace, especially among households with access to modern fuels. Experience shows that people tend to use modern fuels for quick tasks, such as preparing a cup of tea, but prefer to use biomass fuels for foods that take longer to cook. Therefore, changes in the choice of foods in the household menu have the potential to affect the transition to modern fuels. This paper discusses the potential of innovative and emerging aspects of food systems in low-income countries to impact on households. It starts by looking at the processing of indigenous crops to create convenient and nutritious food products. This leads to an overview of the rapid growth of the food processing industry and future opportunities. Consuming food that has been prepared outside of the home is also a common and rapidly growing practice, which is likely to be driven (and disrupted) by technological innovation. Cooking energy considerations depend largely on fuel stacking behaviours, and the paper argues that modern food systems have the potential to reduce energy consumption in the kitchen, and to play a role in displacing traditional biomass fuels with modern fuels.
High-Frequency Modeling of a Three-Winding Power Transformer Using Sweep Frequency Response Analysis
Authors: Yoon Yeunggurl , Son Yongju , Cho Jintae , Jang SuHyeong , Kim Young-Geun , Choi Sungyun
Published: July 2021

A power transformer is an essential device for stable and reliable power transfer to customers. Therefore, accurate modeling of transformers is required for simulation-based analysis with the model. The paper proposes an efficient and straightforward parameter estimation of power transformers based on sweep frequency response analysis (SFRA) test data. The method first develops a transformer model consisting of repetitive RLC sections and mutual inductances and then aligns the simulated SFRA curve with the measured one by adjusting parameters. Note that this adjustment is based on individual parameter impacts on the SFRA curve. After aligning the two curves, the final transformer model can be obtained. In this paper, actual single-phase, three-winding transformer model parameters were estimated based on field SFRA data, showing that SFRA curves simulated from the estimated model are consistent with the measured data.
Modeling of Harmonic Current in Electrical Grids with Photovoltaic Power Integration Using a Nonlinear Autoregressive with External Input Neural Networks
Authors: Jumilla-Corral Adán Alberto , Perez-Tello Carlos , Campbell-Ramírez Héctor Enrique , Medrano-Hurtado Zulma Yadira , Mayorga-Ortiz Pedro , Avitia Roberto L.
Published: July 2021

This research presents the modeling and prediction of the harmonic behavior of current in an electric power supply grid with the integration of photovoltaic power by inverters using artificial neural networks to determine if the use of the proposed neural network is capable of capturing the harmonic behavior of the photovoltaic energy integrated into the user’s electrical grids. The methodology used was based on the use of recurrent artificial neural networks of the nonlinear autoregressive with external input type. Work data were obtained from experimental sources through the use of a test bench, measurement, acquisition, and monitoring equipment. The input–output parameters for the neural network were the current values in the inverter and the supply grid, respectively. The results showed that the neural network can capture the dynamics of the analyzed system. The generated model presented flexibility in data handling, allowing to represent and predict the behavior of the harmonic phenomenon. The obtained algorithm can be transferred to physical or virtual systems for the control or reduction of harmonic distortion.
Harmonic Effects Due to the High Penetration of Photovoltaic Generation into a Distribution System
Authors: Pereira Jorge Luiz Moreira , Leal Adonis Ferreira Raiol , Almeida Gabriel Oliveira de , Tostes Maria Emília de Lima
Published: July 2021

The growth in global electricity demand has expanded the search for new energy resources. Renewable sources such as photovoltaic (PV) systems have proven to be major alternatives. PV generators connected to distribution grids have exhibited significant growth in the last decade, so it is essential to analyse the impacts resulting from this increase. This work investigated the influence of high PV system penetration in distribution grids in terms of harmonic levels. In particular, this study addressed the distortions in voltage and current waveforms in the presence and absence of PV generators connected to a distribution grid. Additionally, the total harmonic content and the individual harmonic frequencies of voltage and current were analysed. This study was performed with an IEEE 37 bus distribution system and the Open Distribution System Simulator software (OpenDSS). The results show that the voltage limits of some phases far away from a substation can exceed the limits. Furthermore, the total harmonic distortion (THD) and individual harmonic distortion (IHD) levels for voltage and current were significantly high for harmonics of the 3rd, 5th, and 7th orders, where current levels violate the standard levels.