bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Mitochondria in Oocyte Maturation
Authors: Kirillova Anastasia , Smitz Johan E. J. , Sukhikh Gennady T. , Mazunin Ilya
Published: September 2021

With the nucleus as an exception, mitochondria are the only animal cell organelles containing their own genetic information, called mitochondrial DNA (mtDNA). During oocyte maturation, the mtDNA copy number dramatically increases and the distribution of mitochondria changes significantly. As oocyte maturation requires a large amount of ATP for continuous transcription and translation, the availability of the right number of functional mitochondria is crucial. There is a correlation between the quality of oocytes and both the amount of mtDNA and the amount of ATP. Suboptimal conditions of in vitro maturation (IVM) might lead to changes in the mitochondrial morphology as well as alternations in the expression of genes encoding proteins associated with mitochondrial function. Dysfunctional mitochondria have a lower ability to counteract reactive oxygen species (ROS) production which leads to oxidative stress. The mitochondrial function might be improved with the application of antioxidants and significant expectations are laid on the development of new IVM systems supplemented with mitochondria-targeted reagents. Different types of antioxidants have been tested already on animal models and human rescue IVM oocytes, showing promising results. This review focuses on the recent observations on oocytes’ intracellular mitochondrial distribution and on mitochondrial genomes during their maturation, both in vivo and in vitro. Recent mitochondrial supplementation studies, aiming to improve oocyte developmental potential, are summarized.
The Presence and Potential Role of ALDH1A2 in the Glioblastoma Microenvironment
Authors: Sanders Stephanie , Herpai Denise M. , Rodriguez Analiz , Huang Yue , Chou Jeff , Hsu Fang-Chi , Seals Darren , Mott Ryan , Miller Lance D. , Debinski Waldemar
Published: September 2021

Glioblastoma (GBM) is the most aggressive malignant glioma. Therapeutic targeting of GBM is made more difficult due to its heterogeneity, resistance to treatment, and diffuse infiltration into the brain parenchyma. Better understanding of the tumor microenvironment should aid in finding more effective management of GBM. GBM-associated macrophages (GAM) comprise up to 30% of the GBM microenvironment. Therefore, exploration of GAM activity/function and their specific markers are important for developing new therapeutic agents. In this study, we identified and evaluated the expression of ALDH1A2 in the GBM microenvironment, and especially in M2 GAM, though it is also expressed in reactive astrocytes and multinucleated tumor cells. We demonstrated that M2 GAM highly express ALDH1A2 when compared to other ALDH1 family proteins. Additionally, GBM samples showed higher expression of ALDH1A2 when compared to low-grade gliomas (LGG), and this expression was increased upon tumor recurrence both at the gene and protein levels. We demonstrated that the enzymatic product of ALDH1A2, retinoic acid (RA), modulated the expression and activity of MMP-2 and MMP-9 in macrophages, but not in GBM tumor cells. Thus, the expression of ALDH1A2 may promote the progressive phenotype of GBM.
Atomistic Descriptions of Gas-Surface Interactions on Tin Dioxide
Authors: Kucharski Stefan , Blackman Chris
Published: September 2021

Historically, in gas sensing literature, the focus on “mechanisms” has been on oxygen species chemisorbed (ionosorbed) from the ambient atmosphere, but what these species actually represent and the location of the adsorption site on the surface of the solid are typically not well described. Recent advances in computational modelling and experimental surface science provide insights on the likely mechanism by which oxygen and other species interact with the surface of SnO2, providing insight into future directions for materials design and optimisation. This article reviews the proposed models of adsorption and reaction of oxygen on SnO2, including a summary of conventional evidence for oxygen ionosorption and recent operando spectroscopy studies of the atomistic interactions on the surface. The analysis is extended to include common target and interfering reducing gases, such as CO and H2, cross-interactions with H2O vapour, and NO2 as an example of an oxidising gas. We emphasise the importance of the surface oxygen vacancies as both the preferred adsorption site of many gases and in the self-doping mechanism of SnO2.
Diagnostic Algorithm in Patients with Flexion Instability after Cruciate-Retaining Total Knee Arthroplasty: A Case Report
Authors: Moser Lukas B. , Prabhakar Ponnaian , Hess Silvan , Hirschmann Michael T.
Published: September 2021

A posterior flexion instability due to insufficiency of the posterior cruciate ligament (PCL) in cruciate retaining (CR) total knee arthroplasty (TKA) is an important but underdiagnosed problem. We hereby suggest a diagnostic algorithm, as demonstrated by a case report of a male patient suffering from anterior knee pain and instability after CR TKA. Clinical examination was followed by standard anterior–posterior and lateral radiographs. Stress radiographs in 30° and 90° posterior drawer position enabled a dynamic examination of the instability. SPECT/CT was used to determine the TKA component position in all planes and investigate bone tracer uptake (BTU) patterns. At revision surgery, an absent PCL after CR TKA was noted and a semi-constrained TKA was implanted.
Corrosion Resistance of a Plasma-Oxidized Ti6Al4V Alloy for Dental Applications
Authors: Velazquez-Torres N. , Porcayo-Calderon J. , Martinez-Valencia H. , Lopes-Cecenes R. , Rosales-Cadena I. , Sarmiento-Bustos E. , Rocabruno-Valdés C. I. , Gonzalez-Rodriguez J. G.
Published: September 2021

A Ti6Al4V alloy was plasma-oxidized at 600 °C during 1, 2, 3, 5 and 8 h and corroded in an artificial saliva solution. Electrochemical evaluation was performed by using potentiodynamic polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements during 100 h. Corroded specimens were characterized by using Raman spectroscopy and scanning electronic microscopy (SEM). All tests indicated that the highest corrosion resistance was obtained for specimen oxidized during 3 h since the noblest free corrosion potential, lowest passive and corrosion current density values, as well as the highest polarization resistance values were obtained under these circumstances. EIS measurements indicated that the highest impedance and phase angle values obtained for this specimen exhibited a high capacitive behavior typical of a very compact passive film.
Effect of Ni Addition on the Corrosion Resistance of NiTi Alloy Coatings on AISI 316L Substrate Prepared by Laser Cladding
Authors: Feng Yuqiang , Du Zexu , Hu Zhengfei
Published: September 2021

In this paper, an equiatomic NiTi (55NiTi) alloy powder was mixed with pure Ni powder to prepare laser cladding coatings on a 316L stainless steel substrate to study the effect of Ni addition on the microstructure and corrosion resistance of the coatings. The microstructure and phase composition of the coatings were analyzed using a scanning electron microscope (SEM) with configured energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD). OCP (open-circuit potential), PD (potentiodynamic polarization) and EIS (electrochemical impedance spectroscopy) experiments were conducted by a Gamry electrochemical workstation, and corresponding eroded morphologies were observed to evaluate the coating’s anti-corrosion performance. The addition of Ni led to fine and uniform dendrites and dense microstructure under the metallurgical microscope, which were beneficial for the formation of the passive film mainly consisting of titanium dioxide (TiO2). The results show that the pitting potential of the 55NiTi + 5Ni coating was 0.11 V nobler than that of the 55NiTi coating, and the corrosion current density was less than half that of the 55NiTi coating. The corrosion initiated preferentially at the interfaces of dendrites and inter-dendritic areas, then spread first to dendrites rather than in the inter-dendritic areas.
Preparation of ZnO/Bi2O3 Composites as Heterogeneous Thin Film Materials with High Photoelectric Performance on FTO Base
Authors: Nie Yuhan , Xie Yadong , Zheng Ying , Luo Yao , Zhang Jianguo , Yi Zao , Zheng Fusheng , Liu Li , Chen Xifang , Cai Pinggen , Wu Pinghui
Published: September 2021

In recent years, ZnO nanomaterials have achieved great performance in solar energy applications. How to synthesize a ZnO nanocomposite structure with high photoelectric conversion efficiency has become an urgent problem to solved. In this paper, a narrow band gap bismuth trioxide (Bi2O3) coated on a ZnO nanoarray by magnetron sputtering was used to prepare a composite heterojunction ZnO/Bi2O3. Studies have found that ZnO/Bi2O3 exhibits excellent photoelectric conversion performance. By preparing a composite heterostructure of ZnO/Bi2O3, it can effectively compensate for the insufficient absorption of ZnO in the visible light range and inhibit the recombination of carriers within the material. The influence of Bi2O3 thickness on the microstructure and electronic structure of the ZnO/Bi2O3 composite structure was explored and analyzed. The energy gap width of the composite heterostructure decreases with the increase in the Bi2O3 thickness on the surface of the ZnO nanorod array. At the same time, the conductive glass composite film structure is simple to prepare and is very environmentally friendly. The ZnO/Bi2O3 composite heterogeneous material prepared this time is suitable for solar cells, photodetectors, photocatalysis and other fields.
Effect of Thermal Management Approaches on Geometry and Productivity of Thin-Walled Structures of ER 5356 Built by Wire + Arc Additive Manufacturing
Authors: da Silva Leandro João , Ferraresi Henrique Nardon , Araújo Douglas Bezerra , Reis Ruham Pablo , Scotti Américo
Published: September 2021

The present paper aimed at assessing the effect of two thermal management approaches on geometry and productivity of thin-walled structures built by Wire + Arc Additive Manufacturing (WAAM). Thin-walls of ER 5356 (Al5Mg) with different lengths and the same number of layers were deposited via the gas metal arc (GMA) process with the aid of an active cooling technique (near-immersion active cooling—NIAC) under a fixed set of deposition parameters. Then, the same experiment was performed with natural cooling (NC) in air. To characterize the thermal management approaches, the interpass temperature (i.e., the temperature at which subsequent layers are deposited) were monitored by a trailing/leading infrared pyrometer during the deposition time. Finally, thin walls with a fixed length were deposited using the NC and NIAC approaches with equivalent interpass temperatures. As expected, the shorter the wall length the more intense the deposition concentration, heat accumulation, and, thus, geometric deviation. This behavior was more evident and premature for the NC strategy due to its lower heat sinking effectiveness. The main finding was that, regardless of the thermal management technique applied, if the same interpass temperature is selected and maintained, the geometry of the part being built tends to be stable and very similar. However, the total deposition time is somewhat shorter with the NIAC technique due its greater heat sinking advantage. Thus, the NIAC technique facilitates the non-stop manufacturing of small parts and details via WAAM.
First-Principles Study of Linear and Nonlinear Optical Properties of Multi-Layered Borophene
Authors: Sachdeva Geeta , Kaur Sumandeep , Pandey Ravindra , Karna Shashi P.
Published: September 2021

Anisotropic materials are of great interest due to their unique direction-dependent optical properties. Borophene, the two-dimensional analog of graphene consisting of boron atoms, has attracted immense research interest due to its exciting anisotropic electronic and mechanical properties. Its synthesis in several structural polymorphic configurations has recently been reported. The present work reports the layer-dependent optical absorption and hyperpolarizabilities of the buckled borophene (δ6-borophene). The results, based on density functional theory, show that multilayer borophene is nearly transparent with only a weak absorbance in the visible region, reflecting its anisotropic structural characteristics. The static first-order hyperpolarizability significantly increases with the number of layers, due mainly to interactions among the frontier orbitals in multilayer borophene. Transparency in the visible region combined with enhanced nonlinear optical properties makes the multilayer borophene important for future photonics technologies.
Preparation of Zinc Oxide and Zinc Ferrite from Zinc Hypoxide by Wet Process and Electrochemistry
Authors: Li Hui , Fu Yutian , Liang Jinglong , Wang Le , Yan Hongyan , Zhao Linfei
Published: September 2021

With the increase of zinc resource consumption, the recovery and utilization of zinc resources in zinc suboxide has become one of the current research hotspots. In this study, the electrochemical method was used to remove the impurities in the zinc leaching night and enrich the zinc ferrite in the ammonia leaching residue for the solution and ammonia leaching slag after the ammonia leaching of zinc hypoxide, in order to realize the comprehensive utilization of the essence of zinc immersion night and new resources. The results showed that the reduction potentials of copper, lead, cadmium, and zinc in the ammonia leaching solution were analyzed by electrochemical testing methods to be −0.76 V, −0.82 V, −0.94 V, and −1.3 V, respectively. Through constant potential electrodeposition, the removal rate of copper, lead, cadmium. The removal rate of cadmium is 98.73%, and the removal rate of lead and copper is more than 99%. The purified ammonia leaching solution is evaporated at 90 °C for 25 min to obtain basic zinc carbonate. The purity of ZnO obtained after calcination at 500 °C for 120 min is 96.31%. The ammonia leaching residue was pickled with 3 mol·L−1 acetic acid for 30 min to effectively remove PbCO3, and then magnetic separation was carried out with a current intensity of 1.4 A. The final zinc ferrite content was 83.83%.
Step Bunches, Nanowires and Other Vicinal “Creatures”—Ehrlich–Schwoebel Effect by Cellular Automata
Authors: Załuska-Kotur Magdalena , Popova Hristina , Tonchev Vesselin
Published: September 2021

Different patterns can be created on the surface of growing crystals, among which the step bunches and/or step meanders are two of the most studied. The Ehrlich–Schwoebel effect at the surface steps is considered one of the “usual suspects” of such patterning. A direct step barrier is when it is easier to attach a particle to the step from the lower terrace than from the upper terrace. Thus, during the process of crystal growth leads to the formation of meanders, while an inverse barrier leads to step bunching. Based on our vicinal Cellular Automaton model, but this time in (2 + 1)D, we show that the combination of a direct and inverse step barrier and the proper selection of the potential of the well between them leads to the formation of bunched step structures. Following this is the formation of anti-bands. In addition, changing the height of the direct step barrier leads to the growth of nanocolumns, nanowires, and nanopyramids or meanders, in the same system.
Broadband Tunable Terahertz Beam Deflector Based on Liquid Crystals and Graphene
Authors: Shen Yanchun , Wang Jinlan , Wang Qiaolian , Qiao Ximing , Wang Yuye , Xu Degang
Published: September 2021

Terahertz (THz) technology has unique applications in, for example, wireless communication, biochemical characterization, and security inspection. However, high-efficiency, low-cost, and actively tunable THz modulators are still scarce. We propose a broadband tunable THz beam deflector based on liquid crystals (LCs). By a periodic gradual distribution of the orientation of the LC in one direction, a frequency-independent geometric phase modulation is obtained. The LC device with this specific orientation distribution was obtained through ultraviolet polarization exposure. We have verified the broadband beam deflection in both the simulation and experiment. The device can achieve a good spin-coupled beam deflection effect in the 0.8–1.2 Thz band, and the average polarization conversion efficiency exceeds 70%. Moreover, because the electro-optical responsivity of LCs is excellent, graphene transparent electrode layers introduced on the upper and lower substrates enable the deflection modulation to be switched and dynamic tuning to be achieved.
Direct Observation of Induced Graphene and SiC Strengthening in Al–Ni Alloy via the Hot Pressing Technique
Authors: Elkady Omayma A. , Yehia Hossam M. , Ibrahim Aya A. , Elhabak Abdelhalim M. , Elsayed Elsayed. M. , Mahdy Amir A.
Published: September 2021

In this study, Al/5 Ni/0.2 GNPs/x SiC (x = 5, 10, 15, and 20 wt%) nanocomposites were constituted using the powder metallurgy–hot pressing technique. The SiC particles and GNPs were coated with 3 wt% Ag using the electroless deposition technique then mixed with an Al matrix and 5% Ni using ball milling. The investigated powders were hot-pressed at 550 °C and 600 °C and 800 Mpa. The produced samples were evaluated by studying their densification, microstructure, phase, chemical composition, hardness, compressive strength, wear resistance, and thermal expansion. A new intermetallic compound formed between Al and Ni, which is aluminum nickel (Al3Ni). Graphene reacted with the Ni and formed the nickel carbide Ni3C. Additionally, it reacted with the SiC and formed the nickel–silicon composite Ni31Si12 at different percentages. A proper distribution for Ni, GNs, and SiC particles and excellent adhesion were observed. No grain boundaries between the Al matrix particles were discovered. Slight increases in the density values and quite high convergence were revealed. The addition of 0.2 wt% GNs to Al-5Ni increased the hardness value by 47.38% and, by adding SiC-Ag to the Al-5Ni-0.2GNs, the hardness increased gradually. The 20 wt% sample recorded 121.6 HV with a 56.29% increment. The 15 wt% SiC sample recorded the highest compressive strength, and the 20 wt% SiC sample recorded the lowest thermal expansion at the different temperatures. The five Al-Ni-Gr-SiC samples were tested as an electrode for electro-analysis processes. A zinc oxide thin film was successfully prepared by electrodeposition onto samples using a zinc nitrate aqueous solution at 25 °C. The electrodeposition was performed using the linear sweep voltammetric and potentiostatic technique. The effect of the substrate type on the deposition current was fully studied. Additionally, the ohmic resistance polarization values were recorded for the tested samples in a zinc nitrate medium. The results show that the sample containing the Al-5 Ni-0.2 GNs-10% SiC composite is the most acceptable sample for these purposes.
Study on the Microstructure and Spectra of Regrown Quartz Crystals from Chinese Jewelry Market
Authors: Zhou Danyi , Lu Taijin , Dai Huiru , Lv Jieran , Chen Shouming , Song Zhonghua , Zhang Jian
Published: September 2021

Regrown quartz crystals consist of the natural section and the synthetic section grown by hydrothermal technique, which has become popular on the Chinese jewelry market in recent years. Similar gemological properties to those of natural quartz have brought challenges to gem identification and also new questions to scientific research. In this study, microstructure and spectral characteristics of the two sections of regrown quartz crystals were investigated by three dimensional computed tomography system and infrared spectroscopy. Results showed that the natural section has a higher porosity and there are also many micron- to millimeter-sized pores on the interface of the two sections. Different infrared absorption peaks of the two sections at the 3300–3600 cm−1 range were mainly attributed to the different existence state of OH groups. The distinction of microstructure and spectral characteristics between the natural and synthetic sections indicate their different growth condition. Compared with natural quartz, a relatively stable growth environment during the synthetic process leads to a lower porosity and the alkali growth solution could result in the change of the existence state of OH groups in the regrown quartz crystals.
Patterns of Cryptic Diversity and Phylogeography in Four Freshwater Copepod Crustaceans in European Lakes
Authors: Kochanova Elena , Nair Abhilash , Sukhikh Natalia , Väinölä Risto , Husby Arild
Published: September 2021

Comparative phylogeography has become a powerful approach in exploring hidden or cryptic diversity within widespread species and understanding how historical and biogeographical factors shape the modern patterns of their distribution. Most comparative phylogeographic studies so far focus on terrestrial and vertebrate taxa, while aquatic invertebrates (and especially freshwater invertebrates) remain unstudied. In this article, we explore and compare the patterns of molecular diversity and phylogeographic structure of four widespread freshwater copepod crustaceans in European water bodies: the harpacticoids Attheyella crassa, Canthocamptus staphylinus and Nitokra hibernica, and the cyclopoid Eucyclops serrulatus, using sequence data from mtDNA COI and nuclear ITS/18S rRNA genes. The three taxa A. crassa, C. staphylinus and E. serrulatus each consist of deeply diverged clusters and are deemed to represent complexes of species with largely (but not completely) non-overlapping distributions, while in N. hibernica only little differentiation was found, which may however reflect the geographically more restricted sampling. However, the geographical patterns of subdivision differ. The divisions in A. crassa and E. serrulatus follow an east–west pattern in Northern Europe whereas that in C. staphylinus has more of a north–south pattern, with a distinct Fennoscandian clade. The deep mitochondrial splits among populations of A. crassa, C. staphylinus and E. serrulatus (model-corrected distances 26–36%) suggest that divergence of the lineages predate the Pleistocene glaciations. This study provides an insight into cryptic diversity and biogeographic distribution of freshwater copepods.
MtDNA D-Loop Diversity in Alpine Cattle during the Bronze Age
Authors: Granado José , Harmath Marianna , Tecchiati Umberto , Oeggl Klaus , Schibler Jörg , Schlumbaum Angela
Published: September 2021

The Bronze Age in Europe is characterized by major socio-economic changes, including certain aspects of animal husbandry. In the Alpine region archaeozoological data, though not very abundant, reveal that cattle were the most important domestic animals in this time period. They were probably used differently in the lowlands than at higher altitude, traction became more important and people increasingly exploited them for dairy products rather than for meat. Thus, a crucial question in this context is whether these major events are accompanied by changes in genetic diversity of cattle. Here we report partial mtDNA d-loop data (320 bp) obtained by PCR from 40 alpine cattle excavated at different sites in South Tyrol, Italy, and Grisons, Switzerland. Most cattle belong to the main European taurine T3 haplogroup, but a few members of T2 and Q haplogroups were identified. Moreover, genetic diversity measures and population genetic statistics indicate different cattle histories at different sites, including bottlenecks and potential admixture. However, Bronze Age Alpine cattle appear to be linked to modern rural cattle mainly from Italy.
A Long-Term Symbiotic Relationship: Recruitment and Fidelity of the Crab Trapezia on Its Coral Host Pocillopora
Authors: Canizales-Flores H. M. , Rodríguez-Troncoso A. P. , Rodríguez-Zaragoza F. A. , Cupul-Magaña A. L.
Published: September 2021

The symbiotic relationship between the crab Trapezia spp. and pocilloporid corals has been characterized as obligate. Although this relationship is considered common and has been widely registered within the distribution areas of these corals, the initiation of this symbiotic relation and its potential persistence throughout the life cycle of the crustacean is still poorly described. To understand the Trapezia–Pocillopora symbiosis, determining the time and conditions when Trapezia recruits a coral colony and the factors influencing this process are key. Thus, in the present study, healthy, small and unrecruited coral fragments were attached to the substrates (using cable ties) of nearby adult Pocillopora colonies. All fragments were monitored for two years to measure their growth and size at the first evidence of Trapezia crab recruitment, as well as the abundance and permanence of the crabs on the coral fragments. Results showed a relation between the space available (coral volume) and crab recruitment as an increase in substrate complexity is required to provide protection for the crabs and hence maintain the symbiosis, while abiotic conditions such as sea temperature and the distance of the fragments from the adult coral colonies seemingly did not affect the recruitment process. In addition, crabs are able to move between colonies, thus discarding the theory that once recruited, crabs are obligate residents on this specific colony.
Lavage, Simethicone, and Prokinetics—What to Swallow with a Video Capsule
Authors: Keuchel Martin , Kurniawan Niehls , Bota Marc , Baltes Peter
Published: September 2021

The development of new capsules now allows endoscopic diagnosis in all segments of the gastrointestinal tract and comes with new needs for differentiated preparation regimens. Although the literature is steadily increasing, the results of the conducted trials on preparation are sometimes conflicting. The ingestion of simethicone before gastric and small bowel capsule endoscopy for prevention of air bubbles is established. The value of a lavage before small bowel capsule endoscopy (SBCE) is recommended, although not supported by all studies. Ingestion in the morning before the procedure seems useful for the improvement of mucosa visualization. Lavage after swallowing of the capsule seems to improve image quality, and in some studies also diagnostic yield. Prokinetics has been used with first generation capsules to shorten gastric transit time and increase the rate of complete small bowel visualization. With the massively prolonged battery capacity of the new generation small bowel capsules, prokinetics are only necessary in significantly delayed gastric emptying as documented by a real-time viewer. Lavage is crucial for an effective colon capsule or pan-intestinal capsule endoscopy. Mainly high or low volume polyethylene glycol (PEG) is used. Apart from achieving optimal cleanliness, propulsion of the capsule by ingested boosts is required to obtain a complete passage through the colon within the battery lifetime. Boosts with low volume sodium picosulfate (NaP) or diatrizoate (gastrografin) seem most effective, but potentially have more side effects than PEG. Future research is needed for more patient friendly but effective preparations, especially for colon capsule and pan-intestinal capsule endoscopy.
Diagnosis of Diabetes Mellitus Using Gradient Boosting Machine (LightGBM)
Authors: Rufo Derara Duba , Debelee Taye Girma , Ibenthal Achim , Negera Worku Gachena
Published: September 2021

Diabetes mellitus (DM) is a severe chronic disease that affects human health and has a high prevalence worldwide. Research has shown that half of the diabetic people throughout the world are unaware that they have DM and its complications are increasing, which presents new research challenges and opportunities. In this paper, we propose a preemptive diagnosis method for diabetes mellitus (DM) to assist or complement the early recognition of the disease in countries with low medical expert densities. Diabetes data are collected from the Zewditu Memorial Hospital (ZMHDD) in Addis Ababa, Ethiopia. Light Gradient Boosting Machine (LightGBM) is one of the most recent successful research findings for the gradient boosting framework that uses tree-based learning algorithms. It has low computational complexity and, therefore, is suited for applications in limited capacity regions such as Ethiopia. Thus, in this study, we apply the principle of LightGBM to develop an accurate model for the diagnosis of diabetes. The experimental results show that the prepared diabetes dataset is informative to predict the condition of diabetes mellitus. With accuracy, AUC, sensitivity, and specificity of 98.1%, 98.1%, 99.9%, and 96.3%, respectively, the LightGBM model outperformed KNN, SVM, NB, Bagging, RF, and XGBoost in the case of the ZMHDD dataset.
Light Blue Walls and Tan Flooring: A Culture of Belonging in Engineering Making Spaces (or Not?)
Authors: Villanueva Alarcón Idalis , Downey Robert Jamaal , Nadelson Louis , Bouwma-Gearhart Jana , Choi YoonHa
Published: September 2021

The motivation for this exploratory qualitative study is to understand what a culture of belonging may look like across six engineering education making spaces in institutions of higher education in the U.S. The research question for this study was: In what ways are the management, instructors, and staff operating engineering education making spaces influencing a culture of belonging (if any) for engineering students? We examined the transcripts of semi-structured interviews of 49 faculty members and 29 members of management/staff of making spaces, using thematic coding. From the data, we identified four themes that described the culture of belonging being created in these six engineering making spaces: (a) a ‘closed loop’ culture for inclusion, diversity, equity, and access; (b) a ‘transactional, dichotomous’ culture; (c) a ‘band-aid, masquerading’ culture; (d) a potential ‘boundary-crossing’ culture. Our primary conclusion was that created cultures in engineering making spaces are extensions of normative cultures found in traditional engineering classrooms. Additionally, while making spaces were attempting to change this culture in their physical infrastructures, it was deemed that the space leadership needs to expand hiring strategies, the nature of making activities, the ambient/physical appearance of the space, disciplines, and required expertise, to create a truly inclusive and equitable culture of belonging.
Primary Students’ Experiences of Remote Learning during COVID-19 School Closures: A Case Study of Finland
Authors: Loukomies Anni , Juuti Kalle
Published: September 2021

The remote learning period that took place due to the outbreak of the COVID-19 pandemic in the spring of 2020 was a novel experience for many students, teachers and guardians in Finland and globally. To be prepared for similar occasions in the future and to support all students appropriately, it is important to be aware of students’ experiences. In this study, instant video blogging (IVB) was used to collect primary school students’ first-hand reports of their emotions in remote learning situations. Through an experience sampling method, 23 Finnish fifth-grade students (aged 11–12 years) took part in IVB during the remote learning period 18 March 2020–13 May 2020. Students’ expressions related to negative emotional experiences were more diverse than those related to positive ones. Nice was the most often reported positive evaluation related to studying. The most often reported negative feelings were bored and irritated, and the most often reported negative aspects related to learning were difficult tasks or not having learned anything. Towards the end of the research period, positive mentions about returning to school increased. The IVB method offered direct insight into how primary students experienced the remote learning period, which can support preparation for exceptional periods in the future and the development of digital learning solutions.
Impact of Novel Image Preprocessing Techniques on Retinal Vessel Segmentation
Authors: Soomro Toufique A. , Ali Ahmed , Jandan Nisar Ahmed , Afifi Ahmed J. , Irfan Muhammad , Alqhtani Samar , Glowacz Adam , Alqahtani Ali , Tadeusiewicz Ryszard , Kantoch Eliasz , Zheng Lihong
Published: September 2021

Segmentation of retinal vessels plays a crucial role in detecting many eye diseases, and its reliable computerized implementation is becoming essential for automated retinal disease screening systems. A large number of retinal vessel segmentation algorithms are available, but these methods improve accuracy levels. Their sensitivity remains low due to the lack of proper segmentation of low contrast vessels, and this low contrast requires more attention in this segmentation process. In this paper, we have proposed new preprocessing steps for the precise extraction of retinal blood vessels. These proposed preprocessing steps are also tested on other existing algorithms to observe their impact. There are two steps to our suggested module for segmenting retinal blood vessels. The first step involves implementing and validating the preprocessing module. The second step applies these preprocessing stages to our proposed binarization steps to extract retinal blood vessels. The proposed preprocessing phase uses the traditional image-processing method to provide a much-improved segmented vessel image. Our binarization steps contained the image coherence technique for the retinal blood vessels. The proposed method gives good performance on a database accessible to the public named DRIVE and STARE. The novelty of this proposed method is that it is an unsupervised method and offers an accuracy of around 96% and sensitivity of 81% while outperforming existing approaches. Due to new tactics at each step of the proposed process, this blood vessel segmentation application is suitable for computer analysis of retinal images, such as automated screening for the early diagnosis of eye disease.
Applying a Genetic Algorithm to a m-TSP: Case Study of a Decision Support System for Optimizing a Beverage Logistics Vehicles Routing Problem
Authors: Gomes David E. , Iglésias Maria Inês D. , Proença Ana P. , Lima Tânia M. , Gaspar Pedro D.
Published: September 2021

Route optimization has become an increasing problem in the transportation and logistics sector within the development of smart cities. This article aims to demonstrate the implementation of a genetic algorithm adapted to a Vehicle Route Problem (VRP) in a company based in the city of Covilhã (Portugal). Basing the entire approach to this problem on the characteristic assumptions of the Multiple Traveling Salesman Problem (m-TSP) approach, an optimization of the daily routes for the workers assigned to distribution, divided into three zones: North, South and Central, was performed. A critical approach to the returned routes based on the adaptation to the geography of the Zones was performed. From a comparison with the data provided by the company, it is predicted by the application of a genetic algorithm to the m-TSP, that there will be a reduction of 618 km per week of the total distance traveled. This result has a huge impact in several forms: clients are visited in time, promoting provider-client relations; reduction of the fixed costs with fuel; promotion of environmental sustainability by the reduction of logistic routes. All these improvements and optimizations can be thought of as contributions to foster smart cities.
Extensible Chatbot Architecture Using Metamodels of Natural Language Understanding
Authors: Matic Rade , Kabiljo Milos , Zivkovic Miodrag , Cabarkapa Milan
Published: September 2021

In recent years, gradual improvements in communication and connectivity technologies have enabled new technical possibilities for the adoption of chatbots across diverse sectors such as customer services, trade, and marketing. The chatbot is a platform that uses natural language processing, a subset of artificial intelligence, to find the right answer to all users’ questions and solve their problems. Advanced chatbot architecture that is extensible, scalable, and supports different services for natural language understanding (NLU) and communication channels for interactions of users has been proposed. The paper describes overall chatbot architecture and provides corresponding metamodels as well as rules for mapping between the proposed and two commonly used NLU metamodels. The proposed architecture could be easily extended with new NLU services and communication channels. Finally, two implementations of the proposed chatbot architecture are briefly demonstrated in the case study of “ADA” and “COVID-19 Info Serbia”.
Bioinspired Auditory Model for Vowel Recognition
Authors: Abad Peraza Viviana , Ferrández Vicente José Manuel , Martínez Rams Ernesto Arturo
Published: September 2021

In this work, a bioinspired or neuromorphic model to replicate the vowel recognition process for an auditory system is presented. A bioinspired peripheral and central auditory system model is implemented and a neuromorphic higher auditory system model based on artificial neuronal nets for vowel recognition is proposed. For their verification, ten Hispanic Spanish language-speaking adults (five males and five females) were used. With the proposed bioinspired model based on artificial neuronal nets it is possible to recognize with high levels of accuracy and sensibility the vowels phonemes of speech signals and the assessment of cochlear implant stimulation strategies in terms of vowel recognition.
Read Reference Calibration and Tracking for Non-Volatile Flash Memories
Authors: Thiers Johann-Philipp , Nicolas Bailon Daniel , Freudenberger Jürgen , Lu Jianjie
Published: September 2021

The performance and reliability of nonvolatile NAND flash memories deteriorate as the number of program/erase cycles grows. The reliability also suffers from cell-to-cell interference, long data retention time, and read disturb. These processes effect the read threshold voltages. The aging of the cells causes voltage shifts which lead to high bit error rates (BER) with fixed predefined read thresholds. This work proposes two methods that aim on minimizing the BER by adjusting the read thresholds. Both methods utilize the number of errors detected in the codeword of an error correction code. It is demonstrated that the observed number of errors is a good measure for the voltage shifts and is utilized for the initial calibration of the read thresholds. The second approach is a gradual channel estimation method that utilizes the asymmetrical error probabilities for the one-to-zero and zero-to-one errors that are caused by threshold calibration errors. Both methods are investigated utilizing the mutual information between the optimal read voltage and the measured error values. Numerical results obtained from flash measurements show that these methods reduce the BER of NAND flash memories significantly.
Anaerobic Biodegradation of Wheat Straw Lignin: The Influence of Wet Explosion Pretreatment
Authors: Khan Muhammad Usman , Ahring Birgitte Kiaer
Published: September 2021

Large amounts of lignin residue is expected in the future when biorefineries for producing biofuels and bio-products will increase in numbers. It is, therefore, valuable to find solutions for using this resource for the sustained production of useful bioenergy or bio-products. Anaerobic digestion could potentially be an option for converting the biorefinery lignin into a valuable energy product. However, lignin is recalcitrant to biodegradation under anaerobic conditions unless the structure is modified. Wet oxidation followed by steam explosion (wet explosion) was previously found to make significant changes to the lignin structure allowing for biodegradation under anaerobic conditions. In this study, we examine the effect of wet explosion pretreatment for anaerobic digestion of wheat straw lignin under mesophilic (37 °C) conditions. Besides the biorefinery lignin produced from wheat straw, untreated lignin was further tested as feed material for anaerobic digestion. Our results showed that wet exploded lignin pretreated with 2% NaOH showed the highest lignin degradation (41.8%) as well as the highest methane potential of 157.3 ± 9.9 mL/g VS. The untreated lignin with no pretreatment showed the lowest methane yield of 65.8 ± 4.8 and only 3.5% of the lignin was degraded. Overall, increased severity of the pretreatment was found to enhance anaerobic degradation of lignin.
Feasibility of Reducing Operator-to-Passenger Contact for Passenger Screening at the Airport with Respect to the Power Consumption of the System
Authors: Kierzkowski Artur , Kisiel Tomasz
Published: September 2021

So far, airport security screening has only been analysed in terms of efficiency, level of service, and protection against any acts of unlawful interference. Screening procedures have not yet addressed the need to limit operator-to-passenger contact. However, the pandemic situation (COVID-19) has shown that it is a factor that can be a key protection for the health of passengers and operators. The purpose of this paper was to analyse the feasibility of reducing contact between operators and passengers in the airport security screening system by process management with respect to the power consumption of the system. Experimental research was conducted on a real system. A computer simulation was applied to estimate system performance and power consumption. The paper identifies the important findings that expand upon previous knowledge. The results showed that there are two key factors: the experience of operators and proper system structure. These factors can significantly reduce the number of operator-to-passenger contacts and, in parallel, provide lower energy consumption of the system. The results obtained in this article showed that proper management improves the process by up to 37%. This approach expands the World Health Organization’s policy of prevention against COVID-19 and helps to ensure sustainable process management.
Simulation of Perovskite Solar Cells Optimized by the Inverse Planar Method in SILVACO: 3D Electrical and Optical Models
Authors: Fakhri Naser , Salay Naderi Mohammad , Gholami Farkoush Saeid , SaeidNahaei Sanam , Park Si-Na , Rhee Sang-Bong
Published: September 2021

In recent years, perovskite solar cells (PSCs), often referred to as the third generation, have rapidly proliferated. Their most prominent deficiencies are their low efficiency and poor stability. To enhance their productivity, a combination of silicon and perovskite is employed. Here, we present a 3D simulation analysis of various electrical and optical properties of PSCs using the SILVACO simulation software. Using the inverted planar method with inorganic transport materials and the proper selection of anti-reflective coatings with a back contact layer increases the efficiency of PSCs to 28.064%, and enhances their stability without using silicone composites. Several materials, including CaF2, SiO2, and Al2O3, with various thicknesses have been employed to investigate the effect of anti-reflective coatings, and to improve the efficiency of the simulated PSC. The best thickness of the absorbent layer is 500 nm, using a CaF2 anti-reflective coating with an optimal thickness of 110 nm. A polymer composition of Spiro-OMeTAD and inorganic materials Cu2O and NiOx was used as the hole transport material (HTM) and inorganic ZnO was employed as the electron transport material (ETM) to optimize the solar cell efficiency, and an optimized thickness was considered for these materials. Yields of 29.261, 28.064 and 27.325% were obtained for Spiro-OMeTAD/ZnO, Cu2O/ZnO and NiOx/ZnO, respectively. Thus, Spiro-OMeTAD yields the highest efficiency. This material is highly expensive with a complex synthesis and high degradability. We proposed to employ Cu2O to alleviate these problems; however, this reduces the efficiency by 1.197%. As a graphene connector has high flexibility, reduces cell weight, and is cheaper and more accessible compared to other metals, it was regarded as an optimal alternative. The simulation results indicate that using the inverted planar method with inorganic transport materials for graphene-based PSCs is highly promising.
Experimental Investigation of a Double-Acting Vane Pump with Integrated Electric Drive
Authors: Ciurys Marek Pawel , Fiebig Wieslaw
Published: September 2021

The article presents an innovative design solution of a balanced vane pump integrated with an electric motor that has been developed by the authors. The designed and constructed bench, which enables testing of the system: power supply, converter, ntegrated motor—pump assembly and hydraulic load at different motor speeds and different pressures in the hydraulic system, is described. The electromagnetic and hydraulic processes in the motor-pump unit are investigated, and new, previously unpublished, results of experimental studies at steady and dynamic states are presented. The results of the study showed good dynamics of the integrated motor-pump assembly and proved its suitability to control the pump flow rate, and thus, the speed of the hydraulic cylinder or the speed of the hydraulic motor.
The Ukrainian Economy Transformation into the Circular Based on Fuzzy-Logic Cluster Analysis
Authors: Bublyk Myroslava , Kowalska-Styczeń Agnieszka , Lytvyn Vasyl , Vysotska Victoria
Published: September 2021

In the era of limited resources and progressive environmental degradation, the circular economy is a practical application of sustainable development. It is an alternative, but also competitive way to achieve economic growth in accordance with the principles of sustainable development. This issue was considered in this paper in the context of the Ukrainian economy. The Ukrainian economy’s transformation into a circular one needs to find ways to choose practical tools for such a transition, considering the destructive impact of economic activities on the environment, population, and economy. The goal was to develop a method of choosing tools for the circular transformations of economic activities for each cluster and to reduce man-made damage to the environment. Cluster analysis, fuzzy C-means method, and grouping of economic activities were used. Two analyzed sectors turned out to be the most interesting: mining and quarrying, and electricity, gas, steam, and air conditioning supply, which were finally assigned to the cluster with a high level of destructive impact, defined as ‘environmentally unfriendly’. The proposed method allows the choice of circular transformation tools for economic activities depending on the destructive impact of these economic activities within each cluster.
Thermal Analysis of Solid/Liquid Phase Change in a Cavity with One Wall at Periodic Temperature
Authors: Tomita Shogo , Celik Hasan , Mobedi Moghtada
Published: September 2021

In this study, heat transfer in a square cavity filled with a Phase Change Material (PCM) under a sinusoidal wall temperature during solidification and melting is analyzed. All surfaces of the cavity are insulated except one surface, which is under the sinusoidal temperature change. The governing equations and boundary conditions are made dimensionless to reduce the number of governing parameters into two as dimensionless frequency and Stefan number. The governing equations were solved numerically by using Finite Volume Method for a wide range of Stefan number (0.1 < Ste < 1.0) and dimensionless frequency (0.23 < ω* < 2.04). Based on the obtained results, a chart in terms of Stefan number and dimensionless frequency is obtained to divide the heat transfer process in the cavity into three regions as uncompleted, completed, and overheated phase-change processes. For the uncompleted process, some parts of the cavity are inactive, and no phase change occurs in those parts of the cavity during the melting and freezing process. For the overheated phase change, the temperature of the cavity highly increases (or decreases), causing the sensible heat storage to compete with latent thermal storage. In the completed process, almost all thermal storage is done by the utilization of latent heat. The suggested graph helps thermal designers to avoid wrong designs and predict the type of thermal storage (sensible or latent) in the cavity without doing any computations.