bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastrointestinal Dysfunction in Parkinson’s Disease: Current and Potential Therapeutics
Authors: Han Myat Noe , Finkelstein David I. , McQuade Rachel M. , Diwakarla Shanti
Published: January 2022

Abnormalities in the gastrointestinal (GI) tract of Parkinson’s disease (PD) sufferers were first reported over 200 years ago; however, the extent and role of GI dysfunction in PD disease progression is still unknown. GI dysfunctions, including dysphagia, gastroparesis, and constipation, are amongst the most prevalent non-motor symptoms in PD. These symptoms not only impact patient quality of life, but also complicate disease management. Conventional treatment pathways for GI dysfunctions (i.e., constipation), such as increasing fibre and fluid intake, and the use of over-the-counter laxatives, are generally ineffective in PD patients, and approved compounds such as guanylate cyclase C agonists and selective 5-hyroxytryptamine 4 receptor agonists have demonstrated limited efficacy. Thus, identification of potential targets for novel therapies to alleviate PD-induced GI dysfunctions are essential to improve clinical outcomes and quality of life in people with PD. Unlike the central nervous system (CNS), where PD pathology and the mechanisms involved in CNS damage are relatively well characterised, the effect of PD at the cellular and tissue level in the enteric nervous system (ENS) remains unclear, making it difficult to alleviate or reverse GI symptoms. However, the resurgence of interest in understanding how the GI tract is involved in various disease states, such as PD, has resulted in the identification of novel therapeutic avenues. This review focuses on common PD-related GI symptoms, and summarizes the current treatments available and their limitations. We propose that by targeting the intestinal barrier, ENS, and/or the gut microbiome, may prove successful in alleviating PD-related GI symptoms, and discuss emerging therapies and potential drugs that could be repurposed to target these areas.
Diffusion on the Peer-to-Peer Network
Authors: Riposo Julien
Published: January 2022

In a peer-to-peer complex environment, information is permanently diffused. Such an environment can be modeled as a graph, where there are flows of information. The interest of such modeling is that (1) one can describe the exchanges through time from an initial state of the network, (2) the description can be used through the fit of a real-world case and to perform further forecasts, and (3) it can be used to trace information through time. In this paper, we review the methodology for describing diffusion processes on a network in the context of exchange of information in a crypto (Bitcoin) peer-to-peer network. Necessary definitions are posed, and the diffusion equation is derived by considering two different types of Laplacian operators. Equilibrium conditions are discussed, and analytical solutions are derived, particularly in the context of a directed graph, which constitutes the main innovation of this paper. Further innovations follow as the inclusion of boundary conditions, as well as the implementation of delay in the diffusion equation, followed by a discussion when doing approximations useful for the implementation. Numerous numerical simulations additionally illustrate the theory developed all along the paper. Specifically, we validated, through simple examples, the derived analytic solutions, and implemented them in more sophisticated graphs, e.g., the ring graph, particularly important in crypto peer-to-peer networks. As a conclusion for this article, we further developed a theory useful for fitting purposes in order to gain more information on its diffusivity, and through a modeling which the scientific community is aware of.
The Impact of Chatbots on Customer Loyalty: A Systematic Literature Review
Authors: Jenneboer Liss , Herrando Carolina , Constantinides Efthymios
Published: January 2022

More and more companies have implemented chatbots on their websites to provide support to their visitors on a 24/7 basis. The new customer wants to spend less and less time and therefore expects to reach a company anytime and anywhere, regardless of time, location, and channel. This study provides insight into the influence of chatbots on customer loyalty. System quality, service quality, and information quality are crucial dimensions that a chatbot must meet to give a good customer experience. To make a chatbot more personal, companies can alter the language style. Human-like chatbots lead to greater satisfaction and trust among customers, leading to greater adoption of the chatbot. The results of this study showed that a connection between chatbots and customer loyalty is very likely. Besides, some customers suffer from the privacy paradox because of personalization. Implications of this study are discussed.
Modelling Runoff within a Small River Basin under the Changing Climate: A Case Study of Using SWAT in the Bălțata River Basin (The Republic of Moldova)
Authors: Sîrodoev Igor , Corobov Roman , Sîrodoev Ghennadi , Trombitsky Ilya
Published: January 2022

The article focuses on modelling surface runoff in a small river basin taking into consideration climate change projections. The runoff was modelled using the Soil and Water Assessment Tool (SWAT), while three Representative Concentration Pathways (RCP2.6, RCP4.5, and RCP8.5) were considered for modelling the future climate. Despite the identified uncertainties, all the scenarios pointed towards decreasing runoff and losing available water resources. The expected runoff of the case study basin (Bălțata River in the Republic of Moldova) will decrease under all considered scenarios. The risk of diminishing runoff will be low in the middle-term perspective and moderate in the long-term one, if considered from the yearly changes. However, there are months with a high risk of diminishing runoff, especially important for proper crop production. While in the middle-term perspective, traditional adaptation measures can be used, in the long-term one, a totally new approach should be sought.
The Potential of SEA in Fostering European Agriculture Policy and Strategies—Challenges and Opportunities
Authors: Rega Carlo , Partidario Maria do Rosario , Martins Rute , Baldizzone Giorgio
Published: January 2022

Agriculture presents one of the central global pressures on biodiversity and climate. In the EU, the Green Deal, the Farm to Fork, and the Biodiversity Strategy 2030 set ambitious environmental targets, acknowledging the key role of agriculture for their achievement. It is, therefore, crucial to integrate such targets in the European Commission’s Common Agricultural Policy (CAP). The CAP 2023–2027 will be implemented through the national CAP Strategic Plans, subject to Strategic Environmental Assessment (SEA). This presents an unprecedented opportunity to steer agriculture towards sustainability. This paper aims to elaborate the role of SEA in CAP Strategic Plans by identifying the links between the strategies mentioned above and SEA, learnings from previous SEA experience in Rural development programs, and collecting experts and stakeholders’ views on the topic. We maintain that SEA of CAP Plans should adopt a strategic approach rather than an impact-based one. Relying on the Critical Decision Factors, we exemplify how this approach can be applied to the key objective of reducing mineral fertilizers and chemical pesticides. We show how SEA could be pivotal in this regard and identify three enabling Critical Decision Factors: knowledge transfer, governance, and the need to bring industries into the forum.
Peer Effects in Housing Size in Rural China
Authors: Li Tianjiao , Feng Changchun , Xi Hao , Guo Yongpei
Published: January 2022

In recent decades, rural China has witnessed a housing construction boom. In order to control the rapid growth of rural housing, both central and local governments have established quantitative restrictions on the floor numbers and total housing area; however, these have been relatively ineffective. Current research to explain this rapid growth in rural housing tends to consider independent household behavior, while social interactions among villagers are neglected. Therefore, the aim of this article is to examine the existence of peer effects in the housing size of villagers and whether they differ among different regions to better understand the influence of social interactions on individual housing behaviors, especially in the context of rural China. A spatial autoregressive model with autoregressive disturbances (SARAR) was used to analyze data from the 2014 China Family Panel Studies (CFPS). The results confirm that villagers’ peer effects do exist, indicating that rural households build housing not only to satisfy their dwelling needs but also to keep up with the other villagers’ housing size. Moreover, there are regional disparities in terms of peer effects in rural housing size. Among the three regional parts, the undeveloped region in the western parts showed the largest peer effects. Therefore, local governments, especially from the underdeveloped region, should pay attention to the villagers’ inner motivations behind housing behavior.
Rural Space Modeling—Contemporary Challenges
Authors: Kurowska Krystyna , Kowalczyk Cezary
Published: January 2022

Rural areas feature mainly agricultural land and forests, and they are often referred to as non-urbanized areas whose spatial uniqueness can be credited to the planners’ imagination, environmental and esthetic sensitivity, and environmental awareness [...]
The Historical Development of Constructed Wetlands for Wastewater Treatment
Authors: Vymazal Jan
Published: January 2022

Constructed wetlands (CWs) for wastewater treatment are engineered systems that are designed and operated in order to use all natural processes involved in the removal of pollutants from wastewaters. CWs are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. The basic classification is based on the presence/absence of wastewater on the wetland surface. The subsurface flow of CWs can be classified according to the direction of the flow to horizontal and vertical. The combination of various types of CWs is called hybrid CW. The CWs technology began in the 1950s in Germany, but the major extension across the world occurred during the 1990s and early 2000s. The early CWs in Germany were designed as hybrid CWs; however, during the 1970s and 1980s, horizontal subsurface flow CWs were mostly designed. The stricter limits for nitrogen, and especially ammonia, applied in Europe during the 1990s, brought more attention to vertical subsurface flow and hybrid systems. Constructed wetlands have been used to treat various types of wastewater, including sewage, industrial and agricultural wastewaters, various drainage and runoff waters and landfill leachate. Recently, more attention has also been paid to constructed treatment wetlands as part of a circular economy in the urban environments: it is clear that CWs are a good fit for the new concept of sponge cities.
Quantitative Evaluation of Ecological Stress Caused by Land Use Transitions Considering the Location of Incremental Construction Lands: The Case of Southern Jiangsu in Yangtze River Delta Region
Authors: Li Pingxing , Liu Chonggang , Cao Hui
Published: January 2022

With their significance in connecting socio-economic development and related eco-environmental consequences, land use transitions have gradually become the focus of land change science and sustainability science. Although various research studies have determined the ecological effects of land use transitions and provided suggestions to regulate them, few studies have investigated the different ecological stress of construction lands from the perspective of their spatial locations in ecologically differentiated regions. Taking economically developed and highly urbanized southern Jiangsu in Eastern China as an example, we developed a process-based method to indicate the spatial heterogeneity of ecological suitability and divided southern Jiangsu into five-level ecological zones accordingly. Considering that construction lands in ecological zones with higher ecological suitability levels cause greater ecological stress, we evaluated the ecological stress levels of incremental construction lands at different stages after 1990. Then, we carried out the calculation of county-level ecological stress and county-level zoning based on both the area and ecological stress level of their incremental construction lands. Results indicated that ecological zones with the highest to lowest ecological suitability levels accounted for 49.85%, 25.73%, 15.56%, 6.51%, and 2.34%, respectively. The majority of the incremental construction lands had the highest and moderately high ecological stress levels, and they were mainly distributed in areas along the Yangtze River and around Taihu Lake. The general ecological stress level of southern Jiangsu was at a relatively high level at each stage, but the county-level patterns of ecological stress levels were spatially different. As determined from the relationship between the amount of incremental construction lands and the average stress level associated with these lands in each unit, four types of zones, i.e., H-H, H-L, L-H and L-L zones, were identified, and targeted suggestions on land use regulations were proposed. We conclude that the spatial distribution of incremental construction lands significantly affects their ecological consequences from the perspective of maintaining ecosystem integrity. Both construction lands and ecological suitability are location specific, so the location-oriented evaluations could provide an effective approach for determining the spatial patterns of land use transitions based on spatially differentiated ecological consequences. It is essential to propose location-specific policies to carry out spatially precise ecological restoration and the redistribution of incremental construction lands.
The Prosodic Expression of Sarcasm vs. Sincerity by Heritage Speakers of Spanish
Authors: Rao Rajiv , Ye Ting , Butera Brianna
Published: January 2022

Motivated by existing research gaps exploring heritage Spanish, the current study analyzes the prosodic manifestation of sarcasm versus sincerity in 19 English-dominant, English-Spanish bilinguals residing in the Midwest region of the USA. In order to explore cross-generational effects and source input varieties, a subset of participants from within the same family was analyzed, including their Spanish-dominant, adult immigrant parents, but only for Spanish. Participants produced sarcastic and sincere utterances in response to contextualized stimuli in both English and Spanish. Data were analyzed for f0 mean, f0 range, and speech rate using Praat. A linear mixed-effects analysis examined the main and interactive effects of language, language dominance, gender, bilingual type, place of birth, and age on sarcasm and sincerity. Results show that sincere speech is faster than sarcastic speech and that speakers have a higher speech rate when speaking English as compared to Spanish. Results show that sincere speech is faster than sarcastic speech and that speakers have a higher speech rate when speaking English compared to Spanish. Results also indicate that the effect of attitude on speech rate can be modified by age, and that the effect of language on speech rate can be modified by age, gender, and dominance, as well as a two-way interactive effect of attitude and language on speech rate. Speaking in Spanish yields a higher f0 mean and range. Results also indicate two-way interactive effects of attitude and bilingual type, and language and dominance on f0 mean and range, as well as a three-way interactive effect of attitude, language, and age on f0 mean. In terms of intrafamilial findings, parents and their adult children pattern the same way in Spanish with respect to speech rate and f0, highlighting the role of source input variety. These results expand our knowledge of how different language experiences and sociolinguistic variables influence prosodic outcomes in heritage speakers of Spanish in the USA.
Isoprostanoid Plasma Levels Are Relevant to Cerebral Adrenoleukodystrophy Disease
Authors: Signorini Cinzia , De Felice Claudio , Durand Thierry , Galano Jean-Marie , Oger Camille , Leoncini Silvia , Hayek Joussef , Lee Jetty Chung-Yung , Lund Troy C. , Orchard Paul J.
Published: January 2022

Cerebral adrenoleukodystrophy (ALD) is a rare neuroinflammatory disorder characterized by progressive demyelination. Mutations within the ABCD1 gene result in very long-chain fatty acid (VLCFA) accumulation within the peroxisome, particularly in the brain. While this VLCFA accumulation is known to be the driving cause of the disease, oxidative stress can be a contributing factor. For patients with early cerebral disease, allogeneic hematopoietic stem cell transplantation (HSCT) is the standard of care, and this can be supported by antioxidants. To evaluate the involvement of fatty acid oxidation in the disease, F2-isoprostanes (F2-IsoPs), F2-dihomo-isoprostanes (F2-dihomo-IsoPs) and F4-neuroprostanes (F4-NeuroPs)—which are oxygenated metabolites of arachidonic (ARA), adrenic (AdA) and docosahexaenoic (DHA) acids, respectively—in plasma samples from ALD subjects (n = 20)—with various phenotypes of the disease-were measured. Three ALD groups were classified according to patients with: (1) confirmed diagnosis of ALD but without cerebral disease; (2) cerebral disease in early period post-HSCT (<100 days post-HSCT) and on intravenous N-acetyl-L-cysteine (NAC) treatment; (3) cerebral disease in late period post-HSCT (beyond 100 days post-HSCT) and off NAC therapy. In our observation, when compared to healthy subjects (n = 29), in ALD (i), F2-IsoPs levels were significantly (p < 0.01) increased in all patients, with the single exception of the early ALD and on NAC subjects; (ii) significant elevated (p < 0.0001) amounts of F2-dihomo-IsoPs were detected, with the exception of patients with a lack of cerebral disease; (iii), a significant increase (p < 0.003) in F4-NeuroP plasma levels was detected in all ALD patients. Moreover, F2-IsoPs plasma levels were significantly higher (p = 0.038) in early ALD in comparison to late ALD stage, and F4-NeuroPs were significantly lower (p = 0.012) in ALD subjects with a lack of cerebral disease in comparison to the late disease stage. Remarkably, plasma amounts of all investigated isoprostanoids were shown to discriminate ALD patients vs. healthy subjects. Altogether, isoprostanoids are relevant to the phenotype of X-ALD and may be helpful in predicting the presence of cerebral disease and establishing the risk of progression.
The Impact of Intermittent Hypoxemia on Left Atrial Remodeling in Patients with Obstructive Sleep Apnea Syndrome
Authors: Chen Yung-Lung , Chen Yung-Che , Wang Hui-Ting , Chang Ya-Ting , Fang Yen-Nan , Hsueh Shukai , Liu Wen-Hao , Lin Pei-Ting , Hsu Po-Yuan , Su Mao-Chang , Huang Kuo-Tung , Lin Meng-Chih
Published: January 2022

Obstructive sleep apnea syndrome (OSAS) is a significant risk factor for left atrial (LA) remodeling. Intermittent hypoxemia occurs during the sleep cycle in patients with OSAS and plays a crucial role in cardiovascular pathologies such as stroke, arrhythmia, and coronary artery disease. However, there is very little information about the role of intermittent hypoxemia in LA remodeling in patients with OSAS. In total, 154 patients with sleep-related breathing disorders (SRBD) were prospectively recruited for this study. All enrolled SRBD patients underwent polysomnography and echocardiography. Significant OSAS was defined as an oxygen desaturation index (ODI) of ≥10 per hour. Intermittent hypoxia/reoxygenation (IHR) stimulation was used to test the effect of hypoxia on the viability, reactive oxygen species, apoptosis, and inflammation-associated cytokine expression in the HL-1 cell line. To investigate the effect of patients’ exosomes on HIF-1 and inflammation-associated cytokine expression, as well as the relationship between ODI and their expression, exosomes were purified from the plasma of 95 patients with SRBD and incubated in HL-1 cells. The LA size was larger in patients with significant OSAS than in those without. There was a significant association between ODI, lowest SpO2, mean SpO2, and LA size (all p < 0.05) but not between the apnea–hypopnea index and LA size. IHR condition caused increased LDH activity, reactive oxygen species (ROS) levels, and apoptosis in HL-1 cells and decreased cellular viability (all p < 0.05). The expression of HIF-1α, TNF-α, IL-6, and TGF-β increased in the IHR condition compared with the control (all p < 0.05). The expression of HIF-1α, IL-1β, and IL-6 increased in the HL-1 cells incubated with exosomes from those patients with significant OSAS than those without (all p < 0.05). There was a significantly positive correlation between ODI and the expression of HIF-1α, TNF-α, IL-1β, IL-6, and TGF-β; a significantly negative correlation between mean SpO2 and IL-6 and TGF-β; and a significantly negative correlation between the lowest SpO2 and HIF-1α (all p < 0.05). In conclusion, intermittent hypoxemia was strongly associated with LA remodeling, which might be through increased ROS levels, LDH activity, apoptosis, and the expression of HIF-1α and inflammation-associated cytokines.
Plasma Protein Levels Analysis in Multiple Sclerosis Sardinian Families Identified C9 and CYP24A1 as Candidate Biomarkers
Authors: Nova Andrea , Fazia Teresa , Beecham Ashley , Saddi Valeria , Piras Marialuisa , McCauley Jacob L. , Berzuini Carlo , Bernardinelli Luisa
Published: January 2022

Here we investigate protein levels in 69 multiple sclerosis (MS) cases and 143 healthy controls (HC) from twenty Sardinian families to search for promising biomarkers in plasma. Using antibody suspension bead array technology, the plasma levels of 56 MS-related proteins were obtained. Differences between MS cases and HC were estimated using Linear Mixed Models or Linear Quantile Mixed Models. The proportion of proteins level variability, explained by a set of 119 MS-risk SNPs as to the literature, was also quantified. Higher plasma C9 and CYP24A1 levels were found in MS cases compared to HC (p < 0.05 after Holm multiple testing correction), with protein level differences estimated as, respectively, 0.53 (95% CI: 0.25, 0.81) and 0.42 (95% CI: 0.19, 0.65) times plasma level standard deviation measured in HC. Furthermore, C9 resulted in both statistically significantly higher relapsing-remitting MS (RRMS) and secondary-progressive MS (SPMS) compared to HC, with SPMS showing the highest differences. Instead, CYP24A1 was statistically significantly higher only in RRMS as compared to HC. Respectively, 26% (95% CI: 10%, 44%) and 16% (95% CI: 9%, 39%) of CYP24A1 and C9 plasma level variability was explained by known MS-risk SNPs. Our results highlight C9 and CYP24A1 as potential biomarkers in plasma for MS and allow us to gain insight into molecular disease mechanisms.
A Novel Anti-B7-H3 × Anti-CD3 Bispecific Antibody with Potent Antitumor Activity
Authors: Feng Yan , Xie Kun , Yin Yanxin , Li Bingyu , Pi Chenyu , Xu Xiaoqing , Huang Tao , Zhang Jingming , Wang Bo , Gu Hua , Fang Jianmin
Published: January 2022

B7-H3 plays an important role in tumor apoptosis, proliferation, adhesion, angiogenesis, invasion, migration, and evasion of immune surveillance. It is overexpressed in various human solid tumor tissues. In patients, B7-H3 overexpression correlates with advanced stages, poor clinical outcomes, and resistance to therapy. The roles of B7-H3 in tumor progression make it a potential candidate for targeted therapy. Here, we generated a mouse anti-human B7-H3 antibody and demonstrated its binding activity via Tongji University Suzhou Instituteprotein-based and cell-based assays. We then developed a novel format anti-B7-H3 × anti-CD3 bispecific antibody based on the antibody-binding fragment of the anti-B7-H3 antibody and single-chain variable fragment structure of anti-CD3 antibody (OKT3) and demonstrated that this bispecific antibody mediated potent cytotoxic activities against various B7-H3-positive tumor cell lines in vitro by improving T cell activation and proliferation. This bispecific antibody also demonstrated potent antitumor activity in humanized mice xenograft models. These results revealed that the novel anti-B7-H3 × anti-CD3 bispecific antibody has the potential to be employed in treatment of B7-H3-positive solid tumors.
The Short-Term Antibacterial Activity of Three Selected Endodontic Sealers against Enterococcus faecalis Bacterial Culture
Authors: Rosa Matej , Morozova Yuliya , Moštěk Roman , Holík Pavel , Somolová Lucia , Novotná Barbora , Zábojníková Soňa , Bogdanová Kateřina , Langová Kateřina , Voborná Iva , Pospíšilová Lenka , Kovařík Josef Paul
Published: January 2022

(1) Background: Microorganisms originating from the microflora of the oral cavity are the main cause of the inflammatory diseases of the dental pulp and periapical periodontium, as well as the failure of endodontic treatment. The subsequent root canal treatment is not able to remove all the pathogens, and a small number of viable bacteria remain in the dentine tubules, which must be sealed by endodontic sealers. These sealers should have at least a bacteriostatic effect to prevent the remaining bacteria from reproducing. The aim of this study is to compare the short-term antibacterial activity of three endodontic sealers based on poly-epoxy resin, zinc oxide-eugenol and calcium silicate with a calcium hydroxide-based sealer. Calcium hydroxide is used as temporary intracanal medicament and, thus, should show significant antibacterial activity. (2) Methods: A total of 25 bovine dentine samples infected with Enterococcus faecalis were used in this study. After the sealer placement and a 24 h incubation period, the root canal walls were scraped, and the suspension of dentine fillings was used for a semi-quantitative evaluation of microbial growth. (3) Results: The poly-epoxide resin-based sealer ADSeal™ showed significant antibacterial properties. (4) Conclusions: The highest antibacterial activity was shown in poly-epoxide resin-based sealer group, followed by the zinc oxide-eugenol-based sealer and calcium silicate-based sealer.
Influence of Dissolved Oxygen Level on Chitin–Glucan Complex and Mannans Production by the Yeast Pichia pastoris
Authors: Farinha Inês , Baptista Sílvia , Reis Maria A. M. , Freitas Filomena
Published: January 2022

The yeast Pichia pastoris was cultivated under different dissolved oxygen (DO) levels (5, 15, 30 and 50% of the air saturation) to evaluate its impact on the production of the cell-wall polysaccharide chitin–glucan complex (CGC) and mannans. Decreasing the DO level from 50 to 15% had no significant impact on cell growth but substrate conversion into biomass was improved. Under such conditions, a mannans content in the biomass of 22 wt% was reached, while the CGC content in the biomass was improved from 15 to 18 wt%, confirming that the DO level also impacted on P. pastoris cell-wall composition. Overall mannans and CGC volumetric productivity values of 10.69 and 8.67 g/(L. day) were reached, respectively. On the other hand, the polymers’ composition was not significantly affected by decreasing the DO level. These results demonstrated that considerable energy savings can be made in the polysaccharide production process by reducing the DO level during cultivation of P. pastoris by improving the overall polymers’ productivity without altering their composition. This has impact on the polysaccharide production costs, which is of considerable relevance for process scale-up and products’ commercialization.
2,6-exo-8,10-exo-4-Butyl-9-oxa-4-azatetracyclo[5.3.1.02,6.08,10]undecane-3,5-dione
Authors: Aitken R. Alan , Fotherby Fiona M. , Slawin Alexandra M. Z.
Published: January 2022

The title epoxide was obtained by spontaneous epoxidation of the corresponding unsaturated imide in air or by peracid oxidation. Unambiguous assignment of the 1H- and 13C-NMR spectra is achieved by comparison between analogous compounds and its X-ray structure confirms the exo,exo-configuration.
Fabrication of PLA/PCL/Graphene Nanoplatelet (GNP) Electrically Conductive Circuit Using the Fused Filament Fabrication (FFF) 3D Printing Technique
Authors: Masarra Nour-Alhoda , Batistella Marcos , Quantin Jean-Christophe , Regazzi Arnaud , Pucci Monica Francesca , El Hage Roland , Lopez-Cuesta José-Marie
Published: January 2022

For the purpose of fabricating electrically conductive composites via the fused filament fabrication (FFF) technique whose properties were compared with injection-moulded properties, poly(lactic acid) (PLA) and polycaprolactone (PCL) were mixed with different contents of graphene nanoplatelets (GNP). The wettability, morphological, rheological, thermal, mechanical, and electrical properties of the 3D-printed samples were investigated. The microstructural images showed the selective localization of the GNPs in the PCL nodules that are dispersed in the PLA phase. The electrical resistivity results using the four-probes method revealed that the injection-moulded samples are insulators, whereas the 3D-printed samples featuring the same graphene content are semiconductors. Varying the printing raster angles also exerted an influence on the electrical conductivity results. The electrical percolation threshold was found to be lower than 15 wt.%, whereas the rheological percolation threshold was found to be lower than 10 wt.%. Furthermore, the 20 wt.% and 25 wt.% GNP composites were able to connect an electrical circuit. An increase in the Young’s modulus was shown with the percentage of graphene. As a result, this work exhibited the potential of the FFF technique to fabricate biodegradable electrically conductive PLA-PCL-GNP composites that can be applicable in the electronic domain.
Evolution of Surface Topography and Microstructure in Laser Polishing of Cold Work Steel 1.2379 (AISI D2) Using Quadratic, Top-Hat Shaped Intensity Distributions
Authors: Temmler André , Cortina Magdalena , Ross Ingo , Küpper Moritz E. , Rittinghaus Silja-Katharina
Published: January 2022

Within the scope of this study, basic experimental research was carried out on macro-laser polishing of tool steel 1.2379 (D2) using a square intensity distribution and continuous wave laser radiation. The influence of the individual process parameters on surface topography was analyzed by a systematic investigation of a wide range of process parameters for two different, square laser beam diameters. Contrary to a typical laser polishing approach, it was shown that short interaction times (high scanning velocity and small laser beam dimensions) are required to reduce both micro-roughness and meso-roughness. A significant reduction of surface roughness of approx. 46% was achieved from Raini = 0.33 ± 0.026 µm to Ramin = 0.163 ± 0.018 µm using a focused square laser beam with an edge length of dL,E = 100 µm at a scanning velocity of vscan = 200 mm/s, a laser power PL = 60 W and n = 2 passes. However, characteristic surface features occur during laser polishing and are a direct consequence of the laser polishing process. Martensite needles in the micro-roughness region, undercuts in the meso-roughness region, and surface waviness in the macro-roughness region can dominate different regions of the resulting surface roughness spectrum. In terms of mechanical properties, average surface hardness was determined by hundreds of nano-indentation measurements and was approx. 390 ± 21 HV0.1 and particularly homogeneous over the whole laser polished surface.
Transient Phase-Driven Cyclic Deformation in Additively Manufactured 15-5 PH Steel
Authors: Lam Tu-Ngoc , Wu Yu-Hao , Liu Chia-Jou , Chae Hobyung , Lee Soo-Yeol , Jain Jayant , An Ke , Huang E-Wen
Published: January 2022

The present work extends the examination of selective laser melting (SLM)-fabricated 15-5 PH steel with the 8%-transient-austenite-phase towards fully-reversed strain-controlled low-cycle fatigue (LCF) test. The cyclic-deformation response and microstructural evolution were investigated via in-situ neutron-diffraction measurements. The transient-austenite-phase rapidly transformed into the martensite phase in the initial cyclic-hardening stage, followed by an almost complete martensitic transformation in the cyclic-softening and steady stage. The compressive stress was much greater than the tensile stress at the same strain amplitude. The enhanced martensitic transformation associated with lower dislocation densities under compression predominantly governed such a striking tension-compression asymmetry in the SLM-built 15-5 PH.
Mayenite Synthesis from Hydroxide Precursors: Structure Formation and Active Sites on Its Surface
Authors: Kapishnikov Aleksandr V. , Kenzhin Roman M. , Koskin Anton P. , Volodin Alexander M. , Geydt Pavel V.
Published: January 2022

We studied the formation process of a mayenite structure from hydroxide precursors in different gas media. According to X-ray diffraction data, this method allows a well-crystallized mayenite (Ca12Al14O33 or C12A7) phase to be obtained at low (500–900 °C) temperatures with an insignificant impurity of CaO. It was shown that the lattice parameters for C12A7 obtained in an inert atmosphere (Ar) were lower when compared with similar samples in the air. These results can be explained by the different levels of oxygen nonstoichiometry in the resulting phase. We noted that sintering and crystallization of mayenite proceeds at lower temperatures in Ar than in the air medium. We found the presence of donor and acceptor active sites on the surface of mayenite, which was detected by the spin probe method. The specific (per unit surface) concentration of such sites (2.5 × 1016 m−2 and 1.5 × 1015 m−2 for donor and acceptor sites, respectively) is comparable to that of γ-Al2O3, which is traditionally used as catalyst support. This allows it to be used in adsorption and catalytic technologies, taking into account its high specific surface area (~30–50 m2/g at a low synthesis temperature).
Structural and Optical Characterizations of Cadmium Chalcogenide Layers on Polyamide Formed Using Monotelluropentathionic Acid
Authors: Ivanauskas Remigijus , Samardokas Linas , Sukyte Judita , Zalenkiene Skirma , Ancutiene Ingrida
Published: January 2022

Mixed cadmium tellurides–cadmium sulfide thin layers were formed on the polyamide PA 6. Monotelluropentathionic acid (H2TeS4O6) was used as a precursor of tellurium and sulfur. A low-temperature, nontoxic, and cost-effective SILAR method was applied. Cadmium telluride (CdTe) and sulfide (CdS) layers were formed through the consecutive reactions of sorbed/diffused chalcogens species from telluropentathionate anion (TeS4O62−) with functional groups of polyamide and alkaline cadmium sulfate. The pseudo-second-order rate and Elovich kinetic models were the best fit to quantify an uptake of chalcogens and cadmium on PA 6. The effects of chalcogens and Cd on the structure and optical properties of PA 6 were characterized using UV-Vis and IR spectra. The clear changes of these properties depended on the concentration and exposure time in the precursor solutions. Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were applied in order to evaluate the effect of the chalcogen species on the changes in structure of polyamide 6 films, depending on the exposure time in the solution of the chalcogens precursor and its concentration. The optical bandgap energy of the formed layers was found to be in the order of 1.52–2.36 eV. Studies by scanning electron microscopy and atomic force microscopy reveal that the diameter of the average grain is approximately 30 nm. The grains are conical in shape and unevenly distributed all over the surface of the substrate.
Status of Aluminum Oxide Gate Dielectric Technology for Insulated-Gate GaN-Based Devices
Authors: Calzolaro Anthony , Mikolajick Thomas , Wachowiak Andre
Published: January 2022

Insulated-gate GaN-based transistors can fulfill the emerging demands for the future generation of highly efficient electronics for high-frequency, high-power and high-temperature applications. However, in contrast to Si-based devices, the introduction of an insulator on (Al)GaN is complicated by the absence of a high-quality native oxide for GaN. Trap states located at the insulator/(Al)GaN interface and within the dielectric can strongly affect the device performance. In particular, although AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) provide superior properties in terms of gate leakage currents compared to Schottky-gate HEMTs, the presence of an additional dielectric can induce threshold voltage instabilities. Similarly, the presence of trap states can be detrimental for the operational stability and reliability of other architectures of GaN devices employing a dielectric layer, such as hybrid MIS-FETs, trench MIS-FETs and vertical FinFETs. In this regard, the minimization of trap states is of critical importance to the advent of different insulated-gate GaN-based devices. Among the various dielectrics, aluminum oxide (Al2O3) is very attractive as a gate dielectric due to its large bandgap and band offsets to (Al)GaN, relatively high dielectric constant, high breakdown electric field as well as thermal and chemical stability against (Al)GaN. Additionally, although significant amounts of trap states are still present in the bulk Al2O3 and at the Al2O3/(Al)GaN interface, the current technological progress in the atomic layer deposition (ALD) process has already enabled the deposition of promising high-quality, uniform and conformal Al2O3 films to gate structures in GaN transistors. In this context, this paper first reviews the current status of gate dielectric technology using Al2O3 for GaN-based devices, focusing on the recent progress in engineering high-quality ALD-Al2O3/(Al)GaN interfaces and on the performance of Al2O3-gated GaN-based MIS-HEMTs for power switching applications. Afterwards, novel emerging concepts using the Al2O3-based gate dielectric technology are introduced. Finally, the recent status of nitride-based materials emerging as other gate dielectrics is briefly reviewed.
Investigating the Action Mechanism of Titanium in Alumina–Magnesia Castables by Adding Different Ti-Bearing Compounds
Authors: Tang Hai , Zhou Yuhao , Yuan Wenjie
Published: January 2022

To investigate the action mechanism of titanium, the effects of different Ti-bearing compounds, including CaTiO3, MgTiO3, and nano-TiO2, on the properties of alumina–magnesia castables were studied. By analyzing the phase compositions, microstructures, and physical and mechanical properties of the castables, it was demonstrated that an intermediate product, CaTiO3, was first generated. This was then consumed by solid-solution reactions, and titanium was involved in the liquid formation as the temperature increased. The solid-solution reaction of CA6 (CaAl12O19) was more prominent due to the incorporation of more titanium in the crystal lattice of CA6 instead of spinel (MgAl2O4). Moreover, the liquid formation was strongly promoted when more titanium accompanied the calcium, which finally accelerated the densification and improved the strengths of alumina–magnesia castables. On the whole, castables with CaTiO3 addition presented higher bulk density and excellent strength after the heat treatment. Besides, the castables with 2 wt.% CaTiO3 contents were estimated to possess greater thermal shock resistance.
Some Specifics of Defect-Free Poly-(o-aminophenylene)naphthoylenimide Fibers Preparation by Wet Spinning
Authors: Skvortsov Ivan Y. , Kulichikhin Valery G. , Ponomarev Igor I. , Varfolomeeva Lydia A. , Kuzin Mikhail S. , Razorenov Dmitry Y. , Skupov Kirill M.
Published: January 2022

A series of model experiments were carried out on drops of poly-(o-aminophenylene)naphthoylenimide (PANI-O) solutions in N-methyl-2-pyrrolidone (NMP) surrounded by a coagulant of different compositions as starting points of defect-free fibers spinning by the wet method. An influence of compositions of dopes and multicomponent coagulants on the diffusion kinetics and drop morphology during coagulation has been investigated. It is shown that the defining parameters of the coagulation process are viscoelastic properties of the polymer solution and the diffusion activity of the coagulant, meaning not only the rate of coagulation but also the presence/absence of macro defects in the resulting fiber. The optimal morphology of as-spun fibers is obtained by coagulation of solution in a three-component mixture containing solvent and two precipitants of different activity (water and ethanol). The chosen coagulating mixture was used for the fiber spinning of PANI-O with different molecular weights dopes, and fibers with sufficiently high strength (~250 MPa), moduli (~2.1 MPa), and elongation at break (50%) were obtained.
Compositional Tailoring of Mg–2Zn–1Ca Alloy Using Manganese to Enhance Compression Response and In-Vitro Degradation
Authors: Prasadh Somasundaram , Parande Gururaj , Gupta Manoj , Wong Raymond
Published: January 2022

The present study investigates Mg–2Zn–1Ca/XMn alloys as biodegradable implants for orthopedic fracture fixation applications. The effect of the presence and progressive addition of manganese (X = 0.3, 0.5, and 0.7 wt.%) on the degradation, and post-corrosion compressive response were investigated. Results suggest that the addition of manganese at 0.5 wt.% improved the corrosion resistance of Mg–2Zn–1Ca alloys. The pH values stabilized for the 0.5Mn-containing alloy and displayed a lower corrosion rate when compared to other Mg–2Zn–1Ca/Mn alloys. Mg–2Zn–1Ca showed a progressive reduction in the compressive strength properties at the end of day 21 whereas Mg–2Zn–1Ca/0.3Mn and Mg–2Zn–1Ca/0.5Mn samples showed a decrease until day 14 and stabilized around the same strength range after day 21. The ability of Mg–2Zn–1Ca/0.5Mn alloy to develop a network of protective hydroxide and phosphate layers has resulted in the corrosion control of the alloy. Mg–2Zn–1Ca/0.7Mn displays segregation of Mn particles at the grain boundaries resulting in decreased corrosion protection. The mechanism behind the corrosion protection of Mg–2Zn–1Ca alloys was discussed.
Influence of Accelerating Admixtures on the Reactivity of Synthetic Aluminosilicate Glasses
Authors: Gonzalez-Panicello Laura , Garcia-Lodeiro Ines , Puertas Francisca , Palacios Marta
Published: January 2022

This research aims at gaining a further understanding of the impact of accelerating admixtures on the reactivity of supplementary cementitious materials (SCMs), which are widely used as a clinker replacement in blended cements. This was done on synthetic glasses with controlled composition and structure that mimic two types of real SCMs (slag and calcium-rich fly ash). The effects of DEIPA, TIPA, NaSCN and Na2S2O3 on the glass dissolution, hydration kinetics and reaction products were investigated. The obtained results concluded that the pH of the NaOH solution and the composition of the synthetic glass play a key role on the effect of the admixtures. In 0.1 M NaOH (pH = 13.0), all the studied admixtures inhibited the dissolution of slag-like glasses while they enhanced the dissolution of Ca-rich fly ash-like glasses, being Na2S2O3 the admixture that led to the highest increase of the dissolution rate of the Ca-rich fly ash-type glasses. In 1 M NaOH solutions (pH = 13.8), only the alkali admixtures (NaSCN and Na2S2O3) enhanced the degree of reaction of both glasses. In slag-type glasses pastes mixed with 1 M NaOH, the addition of 2% Na2S2O3 induced the highest increase of their reactivity as inferred by the total heat release and the amount of bound water. This is related to the formation of a high amount of S(II)-AFm, in addition to C-A-S-H, that would increase the aluminium undersaturation of the pore solution and consequently the further dissolution of the glass.
Numerical Simulation of the Effects of Scanning Strategies on the Aluminum Evaporation of Titanium Alloy in the Electron Beam Cold Hearth Melting Process
Authors: Truong Van-Doi , Hyun Yong-Taek , Won Jong Woo , Lee Wonjoo , Yoon Jonghun
Published: January 2022

In the production of titanium alloy, the electron beam cold hearth melting (EBCHM) process is commonly used due to its effectiveness and the high quality of the end product. However, its main drawback is the significant loss of elements such as aluminum (Al) due to evaporation under the vacuum environment. Numerical coupled thermal-flow models were here developed to investigate the effects of scanning strategies on Al loss in a titanium alloy during EBCHM. The validation model was successful in comparison with previously published experimental data. The Al mass fraction results at the outlet of the water-cooled hearth were strongly influenced by changes in the applied scanning strategies. The results indicated that the Al mass fraction loss could be reduced by using the full-hearth scanning strategies.
A Facile Synthesis of Noble-Metal-Free Catalyst Based on Nitrogen Doped Graphene Oxide for Oxygen Reduction Reaction
Authors: Vasiliev Vladimir P. , Manzhos Roman A. , Kochergin Valeriy K. , Krivenko Alexander G. , Kabachkov Eugene N. , Kulikov Alexander V. , Shulga Yury M. , Gutsev Gennady L.
Published: January 2022

A simple method for the mechanochemical synthesis of an effective metal-free electrocatalyst for the oxygen reduction reaction was demonstrated. A nitrogen-doped carbon material was obtained by grinding a mixture of graphene oxide and melamine in a planetary ball mill. The resulting material was characterized by XPS, EPR, and Raman and IR spectroscopy. The nitrogen concentration on the N-bmGO surface was 5.5 at.%. The nitrogen-enriched graphene material (NbmGO has half-wave potential of −0.175/−0.09 V and was shown to possess high activity as an electrocatalyst for oxygen reduction reaction. The electrocatalytic activity of NbmGO can be associated with a high concentration of active sites for the adsorption of oxygen molecules on its surface. The high current retention (93% for 12 h) after continuous polarization demonstrates the excellent long-term stability of NbmGO.
A Model for Flywheel Fault Diagnosis Based on Fuzzy Fault Tree Analysis and Belief Rule Base
Authors: Cheng Xiaoyu , Liu Shanshan , He Wei , Zhang Peng , Xu Bing , Xie Yawen , Song Jiayuan
Published: January 2022

In the fault diagnosis of the flywheel system, the input information of the system is uncertain. This uncertainty is mainly caused by the interference of environmental factors and the limited cognitive ability of experts. The BRB (belief rule base) shows a good ability for dealing with problems of information uncertainty and small sample data. However, the initialization of the BRB relies on expert knowledge, and it is difficult to obtain the accurate knowledge of flywheel faults when constructing BRB models. Therefore, this paper proposes a new BRB model, called the FFBRB (fuzzy fault tree analysis and belief rule base), which can effectively solve the problems existing in the BRB. The FFBRB uses the Bayesian network as a bridge, uses an FFTA (fuzzy fault tree analysis) mechanism to build the BRB’s expert knowledge, uses ER (evidential reasoning) as its reasoning tool, and uses P-CMA-ES (projection covariance matrix adaptation evolutionary strategies) as its optimization model algorithm. The feasibility and superiority of the proposed method are verified by an example of a flywheel friction torque fault tree.