bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon and Nitrogen Sources Have No Impact on the Organization and Composition of Ustilago maydis Respiratory Supercomplexes
Authors: Matuz-Mares Deyamira , Flores-Herrera Oscar , Guerra-Sánchez Guadalupe , Romero-Aguilar Lucero , Vázquez-Meza Héctor , Matus-Ortega Genaro , Martínez Federico , Pardo Juan Pablo
Published: January 2021

Respiratory supercomplexes are found in mitochondria of eukaryotic cells and some bacteria. A hypothetical role of these supercomplexes is electron channeling, which in principle should increase the respiratory chain efficiency and ATP synthesis. In addition to the four classic respiratory complexes and the ATP synthase, U. maydis mitochondria contain three type II NADH dehydrogenases (NADH for reduced nicotinamide adenine dinucleotide) and the alternative oxidase. Changes in the composition of the respiratory supercomplexes due to energy requirements have been reported in certain organisms. In this study, we addressed the organization of the mitochondrial respiratory complexes in U. maydis under diverse energy conditions. Supercomplexes were obtained by solubilization of U. maydis mitochondria with digitonin and separated by blue native polyacrylamide gel electrophoresis (BN-PAGE). The molecular mass of supercomplexes and their probable stoichiometries were 1200 kDa (I1:IV1), 1400 kDa (I1:III2), 1600 kDa (I1:III2:IV1), and 1800 kDa (I1:III2:IV2). Concerning the ATP synthase, approximately half of the protein is present as a dimer and half as a monomer. The distribution of respiratory supercomplexes was the same in all growth conditions. We did not find evidence for the association of complex II and the alternative NADH dehydrogenases with other respiratory complexes.
How Do Machines Learn? Artificial Intelligence as a New Era in Medicine
Authors: Koteluk Oliwia , Wartecki Adrian , Mazurek Sylwia , Kołodziejczak Iga , Mackiewicz Andrzej
Published: January 2021

With an increased number of medical data generated every day, there is a strong need for reliable, automated evaluation tools. With high hopes and expectations, machine learning has the potential to revolutionize many fields of medicine, helping to make faster and more correct decisions and improving current standards of treatment. Today, machines can analyze, learn, communicate, and understand processed data and are used in health care increasingly. This review explains different models and the general process of machine learning and training the algorithms. Furthermore, it summarizes the most useful machine learning applications and tools in different branches of medicine and health care (radiology, pathology, pharmacology, infectious diseases, personalized decision making, and many others). The review also addresses the futuristic prospects and threats of applying artificial intelligence as an advanced, automated medicine tool.
Combination of Genome-Wide Polymorphisms and Copy Number Variations of Pharmacogenes in Koreans
Authors: Han Nayoung , Oh Jung Mi , Kim In-Wha
Published: January 2021

For predicting phenotypes and executing precision medicine, combination analysis of single nucleotide variants (SNVs) genotyping with copy number variations (CNVs) is required. The aim of this study was to discover SNVs or common copy CNVs and examine the combined frequencies of SNVs and CNVs in pharmacogenes using the Korean genome and epidemiology study (KoGES), a consortium project. The genotypes (N = 72,299) and CNV data (N = 1000) were provided by the Korean National Institute of Health, Korea Centers for Disease Control and Prevention. The allele frequencies of SNVs, CNVs, and combined SNVs with CNVs were calculated and haplotype analysis was performed. CYP2D6 rs1065852 (c.100C>T, p.P34S) was the most common variant allele (48.23%). A total of 8454 haplotype blocks in 18 pharmacogenes were estimated. DMD ranked the highest in frequency for gene gain (64.52%), while TPMT ranked the highest in frequency for gene loss (51.80%). Copy number gain of CYP4F2 was observed in 22 subjects; 13 of those subjects were carriers with CYP4F2*3 gain. In the case of TPMT, approximately one-half of the participants (N = 308) had loss of the TPMT*1*1 diplotype. The frequencies of SNVs and CNVs in pharmacogenes were determined using the Korean cohort-based genome-wide association study.
Altered Gut Microbiota in Irritable Bowel Syndrome and Its Association with Food Components
Authors: Barandouzi Zahra A. , Lee Joochul , Maas Kendra , Starkweather Angela R. , Cong Xiaomei S.
Published: January 2021

The interplay between diet and gut microbiota has gained interest as a potential contributor in pathophysiology of irritable bowel syndrome (IBS). The purpose of this study was to compare food components and gut microbiota patterns between IBS patients and healthy controls (HC) as well as to explore the associations of food components and microbiota profiles. A cross-sectional study was conducted with 80 young adults with IBS and 21 HC recruited. The food frequency questionnaire was used to measure food components. Fecal samples were collected and profiled by 16S rRNA Illumina sequencing. Food components were similar in both IBS and HC groups, except in caffeine consumption. Higher alpha diversity indices and altered gut microbiota were observed in IBS compared to the HC. A negative correlation existed between total observed species and caffeine intake in the HC, and a positive correlation between alpha diversity indices and dietary fiber in the IBS group. Higher alpha diversity and gut microbiota alteration were found in IBS people who consumed caffeine more than 400 mg/d. Moreover, high microbial diversity and alteration of gut microbiota composition in IBS people with high caffeine consumption may be a clue toward the effects of caffeine on the gut microbiome pattern, which warrants further study.
A Predictive Model and Risk Factors for Case Fatality of COVID-19
Authors: Álvarez-Mon Melchor , Ortega Miguel A. , Gasulla Óscar , Fortuny-Profitós Jordi , Mazaira-Font Ferran A. , Saurina Pablo , Monserrat Jorge , Plana María N. , Troncoso Daniel , Moreno José Sanz , Muñoz Benjamin , Arranz Alberto , Varona Jose F. , Lopez-Escobar Alejandro , Barco Angel Asúnsolo-del
Published: January 2021

This study aimed to create an individualized analysis model of the risk of intensive care unit (ICU) admission or death for coronavirus disease 2019 (COVID-19) patients as a tool for the rapid clinical management of hospitalized patients in order to achieve a resilience of medical resources. This is an observational, analytical, retrospective cohort study with longitudinal follow-up. Data were collected from the medical records of 3489 patients diagnosed with COVID-19 using RT-qPCR in the period of highest community transmission recorded in Europe to date: February–June 2020. The study was carried out in in two health areas of hospital care in the Madrid region: the central area of the Madrid capital (Hospitales de Madrid del Grupo HM Hospitales (CH-HM), n = 1931) and the metropolitan area of Madrid (Hospital Universitario Príncipe de Asturias (MH-HUPA) n = 1558). By using a regression model, we observed how the different patient variables had unequal importance. Among all the analyzed variables, basal oxygen saturation was found to have the highest relative importance with a value of 20.3%, followed by age (17.7%), lymphocyte/leukocyte ratio (14.4%), CRP value (12.5%), comorbidities (12.5%), and leukocyte count (8.9%). Three levels of risk of ICU/death were established: low-risk level (<5%), medium-risk level (5–20%), and high-risk level (>20%). At the high-risk level, 13% needed ICU admission, 29% died, and 37% had an ICU–death outcome. This predictive model allowed us to individualize the risk for worse outcome for hospitalized patients affected by COVID-19.
Pharmacogenetics of Direct Oral Anticoagulants: A Systematic Review
Authors: Raymond Johanna , Imbert Laurent , Cousin Thibault , Duflot Thomas , Varin Rémi , Wils Julien , Lamoureux Fabien
Published: January 2021

Dabigatran, rivaroxaban, apixaban, edoxaban, and betrixaban are direct oral anticoagulants (DOACs). Their inter-individual variability in pharmacodynamics and pharmacokinetics (transport and metabolism) is high, and could result from genetic polymorphisms. As recommended by the French Network of Pharmacogenetics (RNPGx), the management of some treatments in cardiovascular diseases (as antiplatelet agents, oral vitamin K antagonists, and statins) can rely on genetic testing in order to improve healthcare by reducing therapeutic resistance or toxicity. This paper is a review of association studies between single nucleotide polymorphisms (SNPs) and systemic exposure variation of DOACs. Most of the results presented here have a lot to do with some SNPs of CES1 (rs2244613, rs8192935, and rs71647871) and ABCB1 (rs1128503, rs2032582, rs1045642, and rs4148738) genes, and dabigatran, rivaroxaban, and apixaban. Regarding edoxaban and betrixaban, as well as SNPs in the CYP3A4 and CYP3A5 genes, literature is scarce, and further studies are needed.
Money Decentralization under Direct Democracy Procedures. The Case of Classical Athens
Authors: Economou Emmanouil-Marios L. , Kyriazis Nicholas C. , Kyriazis Nikolaos A.
Published: January 2021

By analyzing the case of Athens during the Classical period (508-323 BCE) the main thesis of this paper is that under direct democracy procedures and the related institutional setup, a monetary system without a Central Bank may function relatively well. We focus on the following issues: (i) Τhe procedures of currency issuing in the Athenian city-state, (ii) why the Athenian drachma become the leading international currency in the Mediterranean world (iii) how and towards which targets monetary policy without a Central Bank was possible (iv) defining the targets of monetary policy and the mechanisms for its implementation (v) the role of money in the economy (vi) the issue of deficit spending (vii) the reasons of the replacement of the Athenian drachma as a leading currency by others from the Hellenistic period onwards (viii) the correlation of our findings regarding the decentralized character of monetary policy in Classical Athens to today’s realities, such as the issue of cryptocurrencies. Our analysis shows that monetary policy without a Central Bank was possible, with its foremost aim being the stability of the currency (mainly, silver coins) in order to enhance trust in it and so, make it an international currency which could outcompete other currencies. Since there was no Central Bank like today, monetary policy decisions were taken by the popular assembly of citizens in combination with the market forces themselves.
Executive Compensation and Firm Performance in New Zealand: The Role of Employee Stock Option Plans
Authors: Ding David K. , Chea Ya Eem
Published: January 2021

We examine the role of employee stock option plans (ESOPs) in mitigating agency problems in New Zealand firms. We find that ESOPs have a significant and positive effect on firm performance relative to their non-ESOP counterparts. This relation appears within a year from the first ESOP announcement, and for two to four years after the announcement. Our results show that ESOPs improve corporate performance by 10 times the cost of the ESOPs’ adoption in the first year of issue. The improvement persists for four years after the first issuance. These findings confirm the effectiveness of employee stock option plans for companies issuing ESOPs compared with companies that do not issue ESOPs, and show how much the value creation of ESOPs contributes to these firms.
The Interplay of Objectivity and Subjectivity in Landscape Character Assessment: Qualitative and Quantitative Approaches and Challenges
Authors: Terkenli Theano , Gkoltsiou Aikaterini , Kavroudakis Dimitris
Published: January 2021

Landscape character assessment (LCA) methods have been used in the past few decades to analyze, classify, and map landscape types, using objective and subjective approaches, with the aid of both quantitative and qualitative data. This paper addresses and critically evaluates the compromises and ways in which contemporary LCA methodologies employ (or profess they employ) objective versus subjective and quantitative versus qualitative data and analytical tools, in their conceptualization and implementation. It begins with an extensive literature review of the ways in which the objective/subjective and the quantitative/qualitative variables interweave in currently practiced or proposed versions of LCA. With the aid of meta-analysis, the paper traces and discusses the recent evolution, methods, concessions, and risks of such endeavors, and develops an integrative conceptual model for critical assessment, analysis, and negotiation of the interplay between objective-subjective and quantitative-qualitative constituent parts of existing LCA methodologies. It concludes by pointing to pitfalls and prospects, in the broader attempt towards a more concerted, integrative approach to LCA development and practice, both appropriate to its challenges and adaptable to time-space-culture-discipline landscape particularities and means of implementation.
Modelling Beach Litter Accumulation on Mediterranean Coastal Landscapes: An Integrative Framework Using Species Distribution Models
Authors: Di Febbraro Mirko , Frate Ludovico , de Francesco Maria Carla , Stanisci Angela , Tozzi Francesco Pio , Varricchione Marco , Carranza Maria Laura
Published: January 2021

Beach litter accumulation patterns are influenced by biotic and abiotic factors, as well as by the distribution of anthropogenic sources. Although the importance of comprehensive approaches to deal with anthropogenic litter pollution is acknowledged, integrated studies including geomorphologic, biotic, and anthropic factors in relation to beach debris accumulation are still needed. In this perspective, Species Distribution Models (SDMs) might represent an appropriate tool to predict litter accumulation probability in relation to environmental conditions. In this context, we explored the applicability of a SDM–type modelling approach (a Litter Distribution Model; LDM) to map litter accumulation in coastal sand dunes. Starting from 180 litter sampling plots combined with fine–resolution variables, we calibrated LDMs from litter items classified either by their material type or origin. We also mapped litter accumulation hotspots. LDMs achieved fair-to-good predictive performance, with LDMs for litter classified by material type performing significantly better than models for litter classified by origin. Accumulation hotspots were mostly localized along the beach, by beach accesses, and at river mouths. In light of the promising results achieved by LDMs in this study, we conclude that this tool can be successfully applied within a coastal litter management context.
Evaluating the Potentiality of Sentinel-2 for Change Detection Analysis Associated to LULUCF in Wallonia, Belgium
Authors: Close Odile , Petit Sophie , Beaumont Benjamin , Hallot Eric
Published: January 2021

Land Use/Cover changes are crucial for the use of sustainable resources and the delivery of ecosystem services. They play an important contribution in the climate change mitigation due to their ability to emit and remove greenhouse gas from the atmosphere. These emissions/removals are subject to an inventory which must be reported annually under the United Nations Framework Convention on Climate Change. This study investigates the use of Sentinel-2 data for analysing lands conversion associated to Land Use, Land Use Change and Forestry sector in the Wallonia region (southern Belgium). This region is characterized by one of the lowest conversion rates across European countries, which constitutes a particular challenge in identifying land changes. The proposed research tests the most commonly used change detection techniques on a bi-temporal and multi-temporal set of mosaics of Sentinel-2 data from the years 2016 and 2018. Our results reveal that land conversion is a very rare phenomenon in Wallonia. All the change detection techniques tested have been found to substantially overestimate the changes. In spite of this moderate results our study has demonstrated the potential of Sentinel-2 regarding land conversion. However, in this specific context of very low magnitude of land conversion in Wallonia, change detection techniques appear to be not sufficient to exceed the signal to noise ratio.
Tracing Agricultural Land Transfer in China: Some Legal and Policy Issues
Authors: Zhou Chao , Liang Yunjuan , Fuller Anthony
Published: January 2021

This paper traces the evolution of land tenure changes in contemporary China since 1949. The transfer of land from peasant households to family farms and commercial sized units is on a vast scale and forms one of the greatest land reforms we have ever seen. The agrarian question forms both the policy and academic context in which this legislative account of land transfer is assessed and raises the question of whether land assembly in China resembles previous agricultural transformation policy and processes in industrialized countries or to what extent it has special characteristics of its own. The security of land holding in rural China, established with the household responsibility system, is seen to mature slowly over three to four periods of adjustment, always protecting the rights of peasants while improving conditions for increasing land productivity, resulting in an extension of the two rights of peasant holdings to three rights in the new millennium. The introduction of a third right, a land management right which is transferable from peasants to outsiders, has enabled a huge land assembly movement affecting millions of small holdings. This process of land tenure restructuring raises such questions as the consequences of the capitalization of agriculture, peasant land dispossession, proletarianization, and the prospect of a future land market in rural China, all topics for further research.
Teaching Adult Immigrants with Limited Formal Education: Theory, Research, and Practice. 2020. Edited by Peyton, Joy K. and Young-Scholten Martha. Bristol: Multilingual Matters, 208p; ISBN: 978-1-78309-996-2
Authors: Alonso González Vanesa
Published: January 2021

Teaching Adult Immigrants with Limited Formal Education: Theory, Research, and Practice is a compendium of the six modules that were the result of the third phase of the EU-Speak Project, European Speakers of Other Languages: Teaching Adult Migrants and Training Their Teachers, an ambitious collaborative research project carried out by several European and American universities with the purpose of orienting second language educators whose target pupils are immigrant second language learners with limited education and literacy. Each chapter covers different linguistic, psycholinguistic, sociolinguistic, and pedagogical issues in order to offer a complete guide to those interested in teaching a second language to this particular group of learners. As a result, the book presents itself as a link between researchers, teachers, policy-makers, and administrators with the common aim of integrating these learners as active members of their new countries through the acquisition of their new languages.
Alterations of Nigral Dopamine Levels in Parkinson’s Disease after Environmental Enrichment and PACAP Treatment in Aging Rats
Authors: Jungling Adel , Reglodi Dora , Maasz Gabor , Zrinyi Zita , Schmidt Janos , Rivnyak Adam , Horvath Gabor , Pirger Zsolt , Tamas Andrea
Published: January 2021

The neuroprotective effects of environmental enrichment and PACAP (pituitary adenylate cyclase-activating polypeptide) are well-described in Parkinson’s disease. The aim of our study is to investigate the beneficial effects of these factors in aging parkinsonian rats. Newborn Wistar rats were divided into standard and enriched groups according to their environmental conditions. Standard animals were raised under regular conditions. During the first five postnatal weeks, enriched pups were placed in larger cages with different objects. Aging animals received (1) saline, (2) 6-hydroxidopamine (6-OHDA), or (3) 6-OHDA + PACAP injections into the left substantia nigra (s.n.). On the seventh postoperative day, the left and right s.n. were collected. The s.n. of young and aging unoperated animals were also examined in our experiment. We determined the dopamine (DA) levels by the HPLC-MS technique, while the sandwich ELISA method was used to measure the Parkinson disease protein 7 (PARK7) protein levels. In healthy animals, we found an age-related decrease of DA levels. In aging parkinsonian-enriched rats, the operation did not result in a significant DA loss. PACAP treatment could prevent the DA loss in both the standard and enriched groups. All injured PACAP-treated rats showed remarkably higher protective PARK7 levels. The protective effect of PACAP correlated with the increase of the DA and PARK7 levels.
Organic Matter in Cometary Environments
Authors: McKay Adam J. , Roth Nathan X.
Published: January 2021

Comets contain primitive material leftover from the formation of the Solar System, making studies of their composition important for understanding the formation of volatile material in the early Solar System. This includes organic molecules, which, for the purpose of this review, we define as compounds with C–H and/or C–C bonds. In this review, we discuss the history and recent breakthroughs of the study of organic matter in comets, from simple organic molecules and photodissociation fragments to large macromolecular structures. We summarize results both from Earth-based studies as well as spacecraft missions to comets, highlighted by the Rosetta mission, which orbited comet 67P/Churyumov–Gerasimenko for two years, providing unprecedented insights into the nature of comets. We conclude with future prospects for the study of organic matter in comets.
Secreted Protein Acidic and Rich in Cysteine as A Regeneration Factor: Beyond the Tissue Repair
Authors: Ghanemi Abdelaziz , Yoshioka Mayumi , St-Amand Jonny
Published: January 2021

Diverse pathologies (inflammation, tissues injuries, cancer, etc.) and physiological conditions (obesity, physical activity, etc.) induce the expression/secretion of the matricellular protein, secrete protein acidic and rich in cysteine (SPARC). SPARC contributes to the creation of an environment that is suitable for tissue regeneration through a variety of roles, including metabolic homeostasis, inflammation reduction, extracellular matrix remodeling and collagen maturation. Such a homeostatic environment optimizes tissue regeneration and improves tissues’ repair ability. These properties that SPARC has within the regeneration contexts could have a variety of applications, such as in obesity, cancer, sarcopenia, diabetes and bioengineering.
LDL-Cholesterol and Platelets: Insights into Their Interactions in Atherosclerosis
Authors: Gąsecka Aleksandra , Rogula Sylwester , Szarpak Łukasz , Filipiak Krzysztof J.
Published: January 2021

Atherosclerosis and its complications, including acute coronary syndromes, are the major cause of death worldwide. The two most important pathophysiological mechanisms underlying atherosclerosis include increased platelet activation and increased low-density lipoproteins (LDL) concentration. In contrast to LDL, oxidized (ox)-LDL have direct pro-thrombotic properties by functional interactions with platelets, leading to platelet activation and favoring thrombus formation. In this review, we summarize the currently available evidence on the interactions between LDL-cholesterol and platelets, which are based on (i) the presence of ox-LDL-binding sites on platelets, (ii) generation of ox-LDL by platelets and (iii) the role of activated platelets and ox-LDL in atherosclerosis. In addition, we elaborate on the clinical implications of these interactions, including development of the new therapeutic possibilities. The ability to understand and modulate mechanisms governing interactions between LDL-cholesterol and platelets may offer new treatment strategies for atherosclerosis prevention.
Influence of the Nanoclay Concentration and Oil Viscosity on the Rheological and Tribological Properties of Nanoclay-Based Ecolubricants
Authors: Fernández-Silva Samuel D. , García-Morales Moisés , Ruffel Charlène , Delgado Miguel A.
Published: January 2021

This manuscript describes a rheological and tribological study carried out on eco-friendly lubricants. These ecolubricants were made up of nanoclays as dispersed phase (a layered nanosilicate (montmorillonite Cloisite 15A) and a fiber-like nanoclay (sepiolite Pangel B20)) and vegetable-based oil as continuous phase (castor oil (CO), high oleic sunflower oil (HOSO) and their mixtures). A series of nanoclay-based ecolubricants were prepared by varying both nanoclay concentration and base oil, and thus, its viscosity. Friction and wear behaviors were assessed by using a ball-on-three plates tribometer cell. The results showed that the fiber-like sepiolite Pangel B20 yielded an important reduction in the wear scar diameter, thus revealing its potential as anti-wear and load-carrying additive in ecolubricant formulations, while Cloisite 15A proved to have friction improving properties. These anti-wear and friction reducing properties were found to be influenced by both nanoclay concentration and oil viscosity.
Effect of Radiation-Induced Cross-Linking on Thermal Aging Properties of Ethylene-Tetrafluoroethylene for Aircraft Cable Materials
Authors: Zhang Xiaodong , Chen Fei , Su Zhimin , Xie Taiping
Published: January 2021

The effects of electron beam irradiation on ethylene-tetrafluoroethylene copolymer (ETFE) were studied. Samples were irradiated in air at room temperature by a universal electron beam accelerator for various doses. The effect of irradiation on samples and the cross-linked ETFE after aging were investigated with respect to thermal characteristics, crystallinity, mechanical properties, and volume resistivity using thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC), universal mechanical tester, and high resistance meter. TGA showed that thermal stability of irradiated ETFE is considerably lower than that of unirradiated ETFE. DSC indicates that crystallinity is altered greatly by cross-link. The analysis of mechanical properties, fracture surface morphology, visco-elastic properties and volume resistivity certify radiation-induced cross-linking is vital to aging properties.
Development of a Model of Crack Propagation in Multilayer Hard Coatings under Conditions of Stochastic Force Impact
Authors: Vereschaka Alexey , Grigoriev Sergey , Chigarev Anatoli , Milovich Filipp , Sitnikov Nikolay , Andreev Nikolay , Sotova Catherine , Bublikov Jury
Published: January 2021

The article deals with the problems of cracking in the structure of multilayered coatings under the conditions of stochastic loading process. A mathematical model has been proposed in order to predict the crack propagation velocity in the coating while taking the influence of interlayer interfaces into account. A technique for calculating the probability density distribution of the coating fracture (failure rate) has been developed. The probability of a change in the crack growth direction is compared with the experimental data that were obtained as a result of the studies focused on the pattern of cracking in the Zr,Nb-(Zr,Nb)N-(Zr,Nb,Al)N and Ti-TiN-(Ti,Cr,Al)N coatings under the conditions of the real stochastic loading of cutting tools during the turning. The influence of the crystalline structure of the coating on the cracking pattern has been studied. The investigation has found the significant effect of the crystalline structure of the coating layers on the cracking pattern.
Enhanced Antioxidant Activity of Ursolic Acid by Complexation with Copper (II): Experimental and Theoretical Study
Authors: Samsonowicz Mariola , Kalinowska Monika , Gryko Kamila
Published: January 2021

The copper (II) complex of ursolic acid (Cu(II) UA) was synthesized and discussed in terms of its infrared, UV–visible spectra, quantum-chemical calculations at B3LYP/6-31G(d) level and antioxidant capacity. The copper (II) complex was stable in methanolic solution with the molar ratio metal:ligand 1:1. The data obtained by FT-IR confirmed the metal ion coordination through the carboxylate anion. The antioxidant properties of ursolic acid and its complex with Cu were discussed on the basis of energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and values of chemical reactivity parameters. The antiradical properties of ursolic acid and the Cu (II) complex were examined against DPPH• and HO• radicals, and the ferric reducing antioxidant power (FRAP) was examined. The Cu(II) complex showed higher antioxidant activity than ursolic acid, i.e., in DPPH• assay, the EC50 for UA was 47.0 mM, whereas, for Cu(II), UA EC50 = 19.5 mM; the FRAP value for UA was 20.8 µMFe2+, and 35.4 µMFe2+ for Cu(II) UA (compound concentration 3 mM). Although there was no distinct difference in the antioxidant activity against HO• between these two chemicals, they were both better HO• scavengers than DPPH• and showed different kinetics in the reaction with DPPH•.
Investigation of Formation Behaviour of Al–Cu Intermetallic Compounds in Al–50vol%Cu Composites Prepared by Spark Plasma Sintering under High Pressure
Authors: Kim Dasom , Kim Kyungju , Kwon Hansang
Published: January 2021

Al–Cu matrix composites with excellent mechanical and thermal properties are among the most promising materials for realising high performance in thermal management systems. However, intermetallic compounds (ICs) formed at the Al/Cu interfaces prevent direct contact between the metals and severely deteriorate the thermal conductivity of the composite. In this study, we systemically investigated the formation behaviour of Al–Cu ICs as a function of compaction pressure at a low temperature of 380 °C. The phases of the Al–Cu ICs formed during sintering were detected via X-ray diffraction, and the layer thickness and average area fraction of each IC at different compaction pressures were analysed via micro-scale observations of the cross-sections of the Al–Cu composites. The ICs were partially formed along the Al/Cu interfaces at high pressures, and the formation region was related to the direction of applied pressure. The Vickers hardness of the Al–Cu composites with ICs was nearly double those calculated using the rule of mixtures. On the other hand, the thermal conductivity of the composites increased with compaction pressure and reached 201 W·m−1·K−1. This study suggests the possibility of employing Al–Cu matrix composites with controlled IC formation in thermal management applications.
Clinical and Histological Differences between Guided Tissue Regeneration with Acellular Dermal Matrix of Porcine Origin and Autologous Connective Tissue: An Animal Study
Authors: Aragoneses Javier , Suárez Ana , Rodríguez Cinthia , Aragoneses Juan Manuel
Published: January 2021

This research aims to evaluate the clinical and histological parametric differences concerning keratinized tissue that result from two regeneration techniques, the subepithelial autologous connective tissue graft (ACTG) and the acellular dermal matrix (MD) of porcine origin, performed on surgical beds on edentulous spaces in an animal model. The parameters of the MD and ACTG groups were compared with samples of the control group (CG) after 15, 45, and 90 days. Nine female white pigs (Sus scrofa domestica) were used, and each animal provided 20 study areas (12 MD and 8 ACTG). At 15 days, the keratin layer thickness in the MD group was greater than those of the ACTG (25.27 vs. 19.95 μm) and the CG (21.2 μm). After 45 days, the MD and ACTG thickness values decreased but were higher than the CG. At 90 days, MD (19.46 μm) obtained a value close to that of CG, and the ACTG decreased to CG (15.53 μm, p < 0.001). The use of an MD may be a viable alternative to the ACTG because of its ability to provide increased keratinized tissue in comparison to the ACTG.
Effect of Magnetized Water on the Stability and Consolidation Compressive Strength of Cement Grout
Authors: Hu Huan-Xiao , Deng Chao
Published: January 2021

In this study, tap water is magnetized by a self-developed device. The conductivity and evaporation of magnetized water (MW) at different temperatures are tested to demonstrate the magnetization mechanism. The results show that the conductivity and evaporation of the magnetized water increase to different degrees compared with regular tap water (RW). The maximum increase in conductivity is 10.6%, and the maximum increase in evaporation is 25.6% and 16.7% at 50 and 80 °C, respectively. Cement grout samples with water-cement ratios (w/c) of 0.5 and 1.0 were prepared with magnetized water. The stability of the cement grout mixed with RW and MW under different magnetic conditions is tested. The compressive strength and SEM images of the hardened cement grout samples mixed with RW and MW (under optimum magnetic conditions) are compared. The cement grout prepared with MW has a higher stability compared to that of the control specimen, and the relative change of bleeding volume of the MW cement grout with w/c = 0.5 and 1 is 67.69% and 24.36%, respectively. MW has a positive effect on the consolidation compressive strength of cement grout. SEM images show that hardened cement grout with MW has more hydrate crystals, more compact filling space between cement particles, more contact points, and fewer voids compared to that of RW. The influence mechanism of MW on the stability of cement grout is analyzed, which provides a theoretical basis for the application of MW in the field of grouting engineering.
Parametric Finite Element Model and Mechanical Characterisation of Electrospun Materials for Biomedical Applications
Authors: Polak-Kraśna Katarzyna , Mazgajczyk Emilia , Heikkilä Pirjo , Georgiadis Anthimos
Published: January 2021

Electrospun materials, due to their unique properties, have found many applications in the biomedical field. Exploiting their porous nanofibrous structure, they are often used as scaffolds in tissue engineering which closely resemble a native cellular environment. The structural and mechanical properties of the substrates need to be carefully optimised to mimic cues used by the extracellular matrix to guide cells’ behaviour and improve existing scaffolds. Optimisation of these parameters is enabled by using the finite element model of electrospun structures proposed in this study. First, a fully parametric three-dimensional microscopic model of electrospun material with a random fibrous network was developed. Experimental results were obtained by testing electrospun poly(ethylene) oxide materials. Parameters of single fibres were determined by atomic force microscopy nanoindentations and used as input data for the model. The validation was performed by comparing model output data with tensile test results obtained for electrospun mats. We performed extensive analysis of model parameters correlations to understand the crucial factors and enable extrapolation of a simplified model. We found good agreement between the simulation and the experimental data. The proposed model is a potent tool in the optimisation of electrospun structures and scaffolds for enhanced regenerative therapies.
Development of Co-Based Amorphous Composite Coatings Synthesized by Laser Cladding for Neutron Shielding
Authors: Liu Xiaobin , Bi Jiazi , Meng Ziyang , Ke Yubin , Li Ran , Zhang Tao
Published: January 2021

Advanced amorphous coatings consisting of Co-based metallic glasses with ultrahigh strength (6 GPa) and high microhardness (up to 17 GPa) can significantly improve the surface properties of matrix materials. However, the intrinsic brittleness of Co-based metallic glasses can lead to the initiation of microcracks caused by the inevitable generation of thermal stress during the laser cladding process, which severely limits the potential application. In this paper, the methods of increasing substrate temperature and fabricating composite coatings with the addition of toughened Fe powders were adopted to inhibit the generation of microcracks in the Co55Ta10B35 amorphous coatings. Moreover, neutron shielding performances of the cladding coatings with high B content were investigated with a wide range of neutron energy (wavelength: 0.15–0.85 nm). The results indicate that the fully amorphous coating and composite ones can be fabricated successfully. The increase in the substrate temperature and the addition of Fe powders can effectively inhibit the initiation and propagation of microcracks. The fully Co-based amorphous coating with high B content (35 at.%) can exhibit excellent neutron shielding performance. With the addition of Fe powders, the neutron shielding performance is reduced gradually due to the dilution effect of B in the composite cladding coatings, but the microcrack will be completely restrained.
Removal of Nickel from Aqueous Solutions by Natural Bentonites from Slovakia
Authors: Šuránek Matej , Melichová Zuzana , Kureková Valéria , Kljajević Ljiljana , Nenadović Snežana
Published: January 2021

In this study, the removal of nickel (Ni(II)) by adsorption from synthetically prepared solutions using natural bentonites (Lieskovec (L), Hliník nad Hronom (S), Jelšový Potok (JP), and Stará Kremnička (SK)) was investigated. All experiments were carried out under batch processing conditions, with the concentration of Ni(II), temperature, and time as the variables. The adsorption process was fast, approaching equilibrium within 30 min. The Langmuir maximum adsorption capacities of the four bentonite samples used were found to be 8.41, 12.24, 21.79, and 21.93 mg g–1, respectively. The results best fitted the pseudo-second-order kinetic model, with constant rates in a range of 0.0948–0.3153 g mg–1 min. The effect of temperature was investigated at temperatures of 20, 30, and 40 °C. Thermodynamic parameters, including standard enthalpy (ΔH0), Gibbs energy (ΔG0), and standard entropy (ΔS0), were calculated. The adsorption of Ni(II) by bentonite samples was an endothermic and spontaneous process. These results indicated that, of the bentonite samples used, the natural bentonites from JP and SK were most suitable for the removal of nickel from synthetically prepared solutions.
Influence of Particle Morphology of Ground Fly Ash on the Fluidity and Strength of Cement Paste
Authors: Ma Juntao , Wang Daguang , Zhao Shunbo , Duan Ping , Yang Shangtong
Published: January 2021

The grinding process has become widely used to improve the fineness and performance of fly ash. However, most studies focus on the particle size distribution of ground fly ash, while the particle morphology is also an important factor to affect the performance of cement paste. This article aims at three different kinds of ground fly ash from the ball mill and vertical mill, and the particle morphology is observed by scanning electron microscopy (SEM) to calculate the spherical destruction (the ratio of spherical particles broken into irregular particles in the grinding process of fly ash), which provides a quantification of the morphology change in the grinding process. The fluidity of cement paste and the strength of cement mortar are tested to study the relation of spherical destruction and fluidity and strength. The results show that the spherical destruction of ground fly ash in a ball mill is more than 80% and that in a vertical mill with a separation system is only 11.9%. Spherical destruction shows a significant relation with the fluidity. To different addition of ground fly ash, the fluidity of cement paste decreases with the increase of spherical destruction. To the strength of cement paste, particle size distribution and spherical destruction are both the key factors. Therefore, spherical destruction is an important measurement index to evaluate the grinding effect of the fly ash mill.
Corrosion Protective Film Formation on Mg Alloy AZ31 by Exposure to Dilute Selenite Solutions
Authors: Feng Zhiyuan , Xu Charles C. , Zhang Dadi , Buchheit Rudolph
Published: January 2021

The study of protective film formation on Mg alloys by exposure to sodium selenite solutions was conducted. Anodic polarization studies, electrochemical impedance spectroscopy studies, morphological analysis, and Energy-dispersive X-ray spectroscopy were performed on AZ31 Mg alloy after coating treatment in different concentrations of sodium selenite. The corrosion resistance was improved by around 5 times compared with control. Improved resistance to localized corrosion was observed in the coatings treated by 5 mM or 10 mM sodium selenite. The protection mechanism was ascribed to the transformation of selenite to insoluble selenium, the formation of insoluble MgSeO3 hydrate, and polymerization of amorphous selenium.
Effect of Different Austempering Heat Treatments on Corrosion Properties of High Silicon Steel
Authors: Franceschi Mattia , Pezzato Luca , Settimi Alessio Giorgio , Gennari Claudio , Pigato Mirko , Polyakova Marina , Konstantinov Dmitry , Brunelli Katya , Dabalà Manuele
Published: January 2021

A novel high silicon austempered (AHS) steel has been studied in this work. The effect of different austenitizing temperatures, in full austenitic and biphasic regime, on the final microstructure was investigated. Specimens were austenitized at 780 °C, 830 °C, 850 °C and 900 °C for 30 min and held isothermally at 350 °C for 30 min. A second heat treatment route was performed which consisted of austenitizing at 900 °C for 30 min and austempering at 300 °C, 350 °C and 400 °C for 30 min. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to evaluate the microstructural evolution. These techniques revealed that the microstructures were composed of carbide-free bainite, ferrite, martensite and retained austenite (RA) in different volume fractions (Vγ). An aqueous borate buffer solution with 0.3 M H3BO3 and 0.075 M Na2B4O7∂10H2O (pH = 8.4) was used for corrosion tests in order to evaluate the influence of the different volume fractions of retained austenite on the corrosion properties of the specimens. The results showed that when increasing the austenitization temperatures, the volume fractions of retained austenite reached a maximum value at 850 °C, and decrease at higher temperatures. The corrosion properties were investigated after 30 min and 24 h immersion by means of potentiodynamic polarization (after 30 min) and electrochemical impedance spectroscopy (after both 30 min and 24 h) tests. The corrosion resistance of the samples increased with increases in the volume fraction of retained austenite due to lower amounts of residual stresses.
Three-Dimensional Printing of Natural Materials Involving Loess-Based Composite Materials Designed for Ecofriendly Applications
Authors: Lee Hyunbae , Kim Jae-Hwan , Bae Seung-Muk , Oh Jiwon , Hwang Heesu , Hwang Jin-Ha
Published: January 2021

In this work, loess-based materials were designed based on a multicomponent composite materials system for ecofriendly natural three-dimensional (3D) printing involving quick lime, gypsum, and water. The 3D printing process was monitored as a function of gypsum content; in terms of mechanical strength and electrical resistance, in the cube-shaped bulk form. After initial optimization, the 3D printing composition was refined to provide improved printability in a 3D printing system. The optimal 3D fabrication allowed for reproducible printing of rectangular columns and cubes. The development of 3D printing materials was scrutinized using a multitude of physicochemical probing tools, including X-ray diffraction for phase identification, impedance spectroscopy to monitor setting behaviors, and mercury intrusion porosimetry to extract the pore structure of loess-based composite materials. Additionally, the setting behavior in the loess-based composite materials was analyzed by investigating the formation of gypsum hydrates induced by chemical reaction between quick lime and water. This setting reaction provides reasonable mechanical strength that is sufficient to print loess-based pastes via 3D printing. Such mechanical strength allows utilization of robotic 3D printing applications that can be used to fabricate ecofriendly structures.
Testing of Eluates from Waterproof Building Materials for Potential Environmental Effects Due to the Behavior of Enchytraeus albidus
Authors: von Wolff Marya , Stephan Dietmar
Published: January 2021

In order to determine the potential environmental impact of construction products, it is necessary to evaluate their influence on organisms exposed to them or their eluates under environmental conditions. The behavior of the white worm Enchytraeus albidus is a useful tool for assessing the potential environmental impact of construction products in contact with water and soil. This study investigates the environmental effects of eluates from two construction products, a reactive waterproofing product, and an injection resin, on the reproduction and avoidance behavior of E. albidus. The eluates were prepared according to existing guidelines. The soil used for the tests was moistened with the eluates of the construction products. The reproduction results of the worms were collected after six weeks of exposure. Offsprings were counted under the microscope and statistically analyzed. Results from the avoidance behavior were collected after 48 h of exposure, and results were compared with the reproduction results. The eluates from both construction products induced significant changes in the reproduction behavior of E. albidus. Undiluted or only slightly diluted eluates of the injection resin drastically reduced the reproduction of the worms, whereas the leaches of the reactive waterproofing product only had a minor effect. The avoidance results for the injection resin indicates that its presence in the habitat is clearly detrimental to the survival of E. albidus, while the avoidance results for the waterproofing resin showed an initial avoidance of the eluates, but no harmful effects were observed. The avoidance test is a way of rapid toxicity screening of environmental samples when time is a critical parameter to measure possible environmental effects. This study shows that ecotoxicological tests using Enchytraeids are a valuable and important tool for understanding the mode of action of eluates from construction products in the environment.
Long-Term Creep and Shrinkage Behavior of Concrete-Filled Steel Tube
Authors: Nguyen Doan-Binh , Lin Wei-Sheng , Liao Wen-Cheng
Published: January 2021

A concrete-filled steel tube (CFT) combines the advantages of concrete and steel in construction and structural applications. However, research on the time-dependent deformation of the CFT under long-term sustained loading are still limited, particularly for stress transfer between the steel tube and concrete due to creep. This study investigated the creep behavior of CFT over a long period of 400 days. The creep and shrinkage strain of CFT was significantly lower than those of concrete that was not confined within a steel tube. The vertical strains of the steel tube and concrete core were almost identical, and it was shown that they were well bonded and acted as a composite. The vertical stress of steel increased by 32.7%, whereas the vertical stress of concrete decreased by 15.8% at 375 days. The stress transfer is notable and cannot be neglected in CFT design. Moreover, the results of creep and shrinkage were compared to prediction values of the B4 model and B4-TW model to verify their validity.