bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors
Authors: Lee Eldred , Anagnost Kaitlin M. , Wang Zhehui , James Michael R. , Fossum Eric R. , Liu Jifeng
Published: April 2021

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.
Fractional SIR-Model for Estimating Transmission Dynamics of COVID-19 in India
Authors: Shah Nita H. , Suthar Ankush H. , Jayswal Ekta N. , Sikarwar Ankit
Published: April 2021

In this article, a time-dependent susceptible-infected-recovered (SIR) model is constructed to investigate the transmission rate of COVID-19 in various regions of India. The model included the fundamental parameters on which the transmission rate of the infection is dependent, like the population density, contact rate, recovery rate, and intensity of the infection in the respective region. Looking at the great diversity in different geographic locations in India, we determined to calculate the basic reproduction number for all Indian districts based on the COVID-19 data till 7 July 2020. By preparing district-wise spatial distribution maps with the help of ArcGIS 10.2, the model was employed to show the effect of complete lockdown on the transmission rate of the COVID-19 infection in Indian districts. Moreover, with the model’s transformation to the fractional ordered dynamical system, we found that the nature of the proposed SIR model is different for the different order of the systems. The sensitivity analysis of the basic reproduction number is done graphically which forecasts the change in the transmission rate of COVID-19 infection with change in different parameters. In the numerical simulation section, oscillations and variations in the model compartments are shown for two different situations, with and without lockdown.
Clinical Associations between Serial Electrocardiography Measurements and Sudden Cardiac Death in Patients with End-Stage Renal Disease Undergoing Hemodialysis
Authors: Lee Hyun Jin , Choe A Reum , Lee HaeJu , Ryu Dong Ryeol , Kang Ea Wha , Park Jung Tak , Lee Su Hwan , Park Junbeom
Published: April 2021

The rate of sudden cardiac death (SCD) for hemodialysis (HD) patients is significantly higher than that observed in the general population and have the highest risk for arrhythmogenic death. In this multi-center study, patients starting hemodialysis in each hospital were enrolled; they underwent regular check-ups in an open-patient clinic. We examined serial electrocardiography (ECG) data in patients undergoing HD and determined their associations with the occurrence of SCD. Of 678 enrolled subjects who underwent serial ECG before and after hemodialysis, 291 died and 39 developed SCD. In all subjects, the QT peak-to-end (QTpe) interval at all leads and QRS duration were shortened after hemodialysis. The SCD group showed a significant change in the QTpe interval of the inferior, anterior, and lateral leads before and after hemodialysis compared with the survivor group (p < 0.001). In the pre-hemodialysis ECG, SCD patients had significantly longer QTpe intervals in all leads (p < 0.001) and a longer QRS duration (92.6 ± 14.0 vs. 100.6 ± 14.9 ms, p = 0.015) than survivors. In conclusion, patients with a longer QTpe interval before hemodialysis and large changes in ECG parameters after hemodialysis might be at a higher risk of SCD. Therefore, changes in the ECG before and after hemodialysis could help to predict SCD.
Impact of HLA Mismatching on Early Subclinical Inflammation in Low-Immunological-Risk Kidney Transplant Recipients
Authors: Hernández Domingo , Vázquez Teresa , Alonso-Titos Juana , León Myriam , Caballero Abelardo , Cobo María Angeles , Sola Eugenia , López Verónica , Ruiz-Esteban Pedro , Cruzado Josep María , Sellarés Joana , Moreso Francesc , Manonelles Anna , Torio Alberto , Cabello Mercedes , Delgado-Burgos Juan , Casas Cristina , Gutiérrez Elena , Jironda Cristina , Kanter Julia , Serón Daniel , Torres Armando
Published: April 2021

The impact of human leukocyte antigen (HLA)-mismatching on the early appearance of subclinical inflammation (SCI) in low-immunological-risk kidney transplant (KT) recipients is undetermined. We aimed to assess whether HLA-mismatching (A-B-C-DR-DQ) is a risk factor for early SCI. As part of a clinical trial (Clinicaltrials.gov, number NCT02284464), a total of 105 low-immunological-risk KT patients underwent a protocol biopsy on the third month post-KT. As a result, 54 presented SCI, showing a greater number of total HLA-mismatches (p = 0.008) and worse allograft function compared with the no inflammation group (48.5 ± 13.6 vs. 60 ± 23.4 mL/min; p = 0.003). Multiple logistic regression showed that the only risk factor associated with SCI was the total HLA-mismatch score (OR 1.32, 95%CI 1.06–1.64, p = 0.013) or class II HLA mismatching (OR 1.51; 95%CI 1.04–2.19, p = 0.032) after adjusting for confounder variables (recipient age, delayed graft function, transfusion prior KT, and tacrolimus levels). The ROC curve illustrated that the HLA mismatching of six antigens was the optimal value in terms of sensitivity and specificity for predicting the SCI. Finally, a significantly higher proportion of SCI was seen in patients with >6 vs. ≤6 HLA-mismatches (62.3 vs. 37.7%; p = 0.008). HLA compatibility is an independent risk factor associated with early SCI. Thus, transplant physicians should perhaps be more aware of HLA mismatching to reduce these early harmful lesions.
The Relationship between Mucins and Ulcerative Colitis: A Systematic Review
Authors: Bankole Esther , Read Emily , Curtis Michael A. , Neves Joana F. , Garnett James A.
Published: April 2021

Mucins are a family of glycosylated proteins which are the primary constituents of mucus and play a dynamic role in the regulation of the protective mucosal barriers throughout the human body. Ulcerative colitis (UC) is an Inflammatory Bowel Disease (IBD) characterised by continuous inflammation of the inner layer of the large intestine, and in this systematic review we analyse currently available data to determine whether alterations exist in mucin activity in the colonic mucosa of UC patients. Database searches were conducted to identify studies published between 1990 and 2020 that assess the role of mucins in cohorts of UC patients, where biopsy specimens were resected for analysis and control groups were included for comparison. 5497 articles were initially identified and of these 14 studies were systematically selected for analysis, a further 2 articles were identified through citation chaining. Therefore, 16 studies were critically reviewed. 13 of these studies assessed the role of MUC2 in UC and the majority of articles indicated that alterations in MUC2 structure or synthesis had an impact on the colonic mucosa, although conflicting results were presented regarding MUC2 expression. This review highlights the importance of further research to enhance our understanding of mucin regulation in UC and summarises data that may inform future studies.
Plasma Rich in Growth Factors (PRGF) in Transepithelial Photorefractive Keratectomy (TPRK)
Authors: Sánchez-González José-María , Alonso-Aliste Federico , Borroni Davide , Amián-Cordero Jonatan , De-Hita-Cantalejo Concepción , Capote-Puente Raúl , Bautista-Llamas María-José , Sánchez-González María Carmen , Rodríguez-Calvo-de-Mora Marina , Rocha-de-Lossada Carlos
Published: April 2021

To evaluate the usage of plasma rich in growth factor (PRGF) in transepithelial photorefractive keratectomy (TPRK) in low and moderate myopia, patients who underwent myopic and astigmatism TPRK with PRGF were involved in this retrospective, observational study. Subjects underwent a surgical procedure between February 2019 and June 2019. A three-month follow-up was recorded. Pain score was assessed with a visual analogue scale (0–10) and re-epithelialization time recorded. A total of 48 eyes from 24 patients were recruited. Mean uncorrected distance visual acuity (UDVA) was 20/20.31 (0.00 ± 0.02 LogMAR). A total of 98% of eyes did not change corrected distance visual acuity (CDVA) lines. Two percent of eyes lost one line of CDVA. Preoperative spherical equivalent was −2.67 ± 1.37 D and after three months changed to −0.21 ± 0.34 D, and 2% of eyes changed 0.50 D or more between one and three months. Pain score was 3.29 ± 0.61 (3 to 6) score points at day one and 0.08 ± 0.27 score points at day seven. Finally, re-epithelialization time was 2.50 ± 1.20 days. PRGF addition to conventional refractive treatment such as TPRK seems to alleviate immediate postoperative pain and positively contribute to corneal re-epithelization time.
Surface Characterisation of Kolk-Boils within Tidal Stream Environments Using UAV Imagery
Authors: Slingsby James , Scott Beth E. , Kregting Louise , McIlvenny Jason , Wilson Jared , Couto Ana , Roos Deon , Yanez Marion , Williamson Benjamin J.
Published: April 2021

High-flow tidal stream environments, targeted for tidal turbine installations, exhibit turbulent features, at fine spatio-temporal scales (metres and seconds), created by site-specific topography and bathymetry. Bed-derived turbulent features (kolk-boils) are thought to have detrimental effects on tidal turbines. Characterisation of kolk-boils is therefore essential to inform turbine reliability, control, and maintenance strategies. It will also improve the understanding of potential ecological interactions with turbines, as marine animals use these sites for foraging. Unmanned aerial vehicle (UAV), or drone, imagery offers a novel approach to take precise measurements of kolk-boil characteristics (distribution, presence, and area) at the surface. This study carried out sixty-three UAV surveys within the Inner Sound of the Pentland Firth, Scotland, UK, over four-day periods in 2016 and 2018. Kolk-boil characteristics were examined against relevant environmental covariates to investigate potential drivers of presence and area. The results show that distribution at the surface could be predicted based on tidal phase, with current velocity significantly influencing presence above 3.0 m/s. The technique can be used to inform turbine development, micro-siting and provide better understanding of environmental implications of turbine operation. Finally, it highlights the suitability of UAVs for capturing rapid fine-scale hydrodynamic data in the absence of in situ measurements.
Experimental Study on the Unsteady Natural Cloud Cavities: Influence of Cavitation Number on Cavity Evolution and Pressure Pulsations
Authors: Sun Tiezhi , Zhang Xiaoshi , Zhang Jianyu , Wang Cong
Published: April 2021

High-speed underwater vehicles are subjected to complex multiphase turbulent processes, such as the growth, development, shedding, and collapse of cavitation bubbles. To study the cavity evolution and pressure pulsation characteristics, in this paper, cloud cavitation over a conical axisymmetric test body with four pressure sensors is investigated. A multi-field simultaneous measurement experiment method for the natural cavitation of underwater vehicles is proposed to understand the relationship between cavity evolution and instantaneous pressure. The results show that the evolution of cloud cavitation can be mainly divided into three stages: (I) the growth process of the attached cavity, (II) the shedding process of the attached cavity, and (III) the collapse of detached cavities. The evolution of the attached cavity and collapse of the large-scale shedding cavity will cause strong pressure pulsations. It is found that the cavitation number plays an important role in cavitation evolution and pressure pulsation. Interestingly, as the cavitation number decreases, the fluctuation intensity of cavitation increases significantly and gradually presents obvious periodicity. Moreover, the unstable cavitating flow patterns are highly correlated with the time domain and frequency domain characteristics of pressure. Especially, as the cavitation number decreases, the main frequency becomes lower and the pressure band becomes more concentrated.
A Topology Optimization Procedure for Assisting the Design of Nuclear Components
Authors: Chabod Sébastien
Published: April 2021

In this paper, we show that a module implemented in the MCNP transport code to perform sensitivity analyses can be diverted to perform topology optimizations of nuclear equipment. Component design with this approach leads to sophisticated solutions that outperform their human-designed counterparts.
Integrative Systems Biology Approaches to Identify Potential Biomarkers and Pathways of Cervical Cancer
Authors: Oany Arafat Rahman , Mia Mamun , Pervin Tahmina , Alyami Salem Ali , Moni Mohammad Ali
Published: April 2021

Nowadays, cervical cancer (CC) is treated as the leading cancer among women throughout the world. Despite effective vaccination and improved surgery and treatment, CC retains its fatality rate of about half of the infected population globally. The major screening biomarkers and therapeutic target identification have now become a global concern. In the present study, we have employed systems biology approaches to retrieve the potential biomarkers and pathways from transcriptomic profiling. Initially, we have identified 76 of each up-regulated and down-regulated gene from a total of 4643 differentially expressed genes. The up-regulatory genes mainly concentrate on immune-inflammatory responses, and the down-regulatory genes are on receptor binding and gamma-glutamyltransferase. The involved pathways associated with these genes were also assessed through pathway enrichment, and we mainly focused on different cancer pathways, immunoresponse, and cell cycle pathways. After the subsequent enrichment of these genes, we have identified 12 hub genes, which play a crucial role in CC and are verified by expression profile analysis. From our study, we have found that genes LILRB2 and CYBB play crucial roles in CC, as reported here for the first time. Furthermore, the survivability of the hub genes was also assessed, and among them, finally, CXCR4 has been identified as one of the most potential differentially expressed genes that might play a vital role in the survival of CC patients. Thus, CXCR4 could be used as a prognostic and/or diagnostic biomarker and a drug target for CC.
Land-Use Impact on Stand Structure and Fruit Yield of Tamarindus indica L. in the Drylands of Southeastern Ethiopia
Authors: Zeleke Gizachew , Dejene Tatek , Tadesse Wubalem , Martín-Pinto Pablo
Published: April 2021

In this study, we evaluated stand status, dendrometric variables, and fruit production of Tamarind (Tamarindus indica L.) trees growing in bushland and farmland-use types in dryland areas of Ethiopia. The vegetation survey was conducted using the point-centered quarter method. The fruit yield of 54 trees was also evaluated. Tree density and fruit production in ha were estimated. There was a significant difference in Tamarind tree density between the two land-use types (p = 0.01). The mean fruit yield of farmland trees was significantly higher than that of bushland trees. However, Tamarind has unsustainable structure on farmlands. Differences in the dendrometric characteristics of trees were also observed between the two land-use types. Predictive models were selected for Tamarind fruit yield estimations in both land-use types. Although the majority of farmland trees produced <5000 fruit year−1, the selection of Tamarind germplasm in its natural ranges could improve production. Thus, the development of management plans to establish stands that have a more balanced diameter structure and thereby ensure continuity of the population and fruit yields is required in this area, particularly in the farmlands. This baseline information could assist elsewhere in areas that are facing similar challenges for the species due to land-use change.
The Health Economic Evaluation of Bariatric Surgery Versus a Community Weight Management Intervention Analysis from the Idiopathic Intracranial Hypertension Weight Trial (IIH:WT)
Authors: Aguiar Magda , Frew Emma , Mollan Susan P. , Mitchell James L. , Ottridge Ryan S. , Alimajstorovic Zerin , Yiangou Andreas , Singhal Rishi , Tahrani Abd A. , Sinclair Alex J.
Published: April 2021

Background: The Idiopathic Intracranial Hypertension Weight Trial (IIH:WT) established the efficacy of bariatric surgery as compared to a community weight management intervention in reducing intracranial pressure in active IIH. The aim of this cost-effectiveness analysis was to evaluate the economic impact of these weight loss treatments for IIH. Methods: IIH:WT was a five-year randomised, controlled, parallel group, multicentre trial in the United Kingdom, where participants with active IIH and a body mass index ≥35 kg/m2 were randomly assigned (1:1) to receive access to bariatric surgery or a community weight management intervention. All clinical and quality of life data was recorded at baseline, 12 and 24 months. Economic evaluation was performed to assess health-care costs and cost-effectiveness. Evaluations were established on an intention to treat principle, followed by a sensitivity analysis using a per protocol analysis. Results: The mean total health care costs were GBP 1353 for the community weight management arm and GBP 5400 for the bariatric surgery arm over 24 months. The majority of costs for the bariatric surgery arm relate to the surgical procedure itself. The 85% who underwent bariatric surgery achieved a 12.5% reduction in intracranial pressure at 24 months as compared to 39% in the community weight management arm; a mean difference of 45% in favour of bariatric surgery. The cost effectiveness of bariatric surgery improved over time. Conclusions: The IIH:WT was the first to compare the efficacy and cost-effectiveness of bariatric surgery with community weight management interventions in the setting of a randomised control trial. The cost-effectiveness of bariatric surgery improved over time and therefore the incremental cost of surgery when offset against the incremental reduction of intracranial pressure improved after 24 months, as compared with 12 months follow up.
Zinc Sulfate Stimulates Osteogenic Phenotypes in Periosteum-Derived Cells and Co-Cultures of Periosteum-Derived Cells and THP-1 Cells
Authors: Park Jin-Ho , Park Su A , Kang Young-Hoon , Hwa So Myeong , Koh Eun-Byeol , Hwang Sun-Chul , Oh Se Heang , Byun June-Ho
Published: April 2021

Coupling between osteoblast-mediated bone formation and osteoclast-mediated bone resorption maintains both mechanical integrity and mineral homeostasis. Zinc is required for the formation, mineralization, growth, and maintenance of bones. We examined the effects of zinc sulfate on osteoblastic differentiation of human periosteum-derived cells (hPDCs) and osteoclastic differentiation of THP-1 cells. Zinc sulfate enhanced the osteoblastic differentiation of hPDCs; however, it did not affect the osteoclastic differentiation of THP-1 cells. The levels of extracellular signaling-related kinase (ERK) were strongly increased during osteoblastic differentiation in zinc sulfate-treated hPDCs, compared with other mitogen-activated protein kinases (MAPKs). Zinc sulfate also promoted osteogenesis in hPDCs and THP-1 cells co-cultured with the ratio of one osteoclast to one osteoblast, as indicated by alkaline phosphatase levels, mineralization, and cellular calcium contents. In addition, the receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio was decreased in the zinc sulfate-treated co-cultures. Our results suggest that zinc sulfate enhances osteogenesis directly by promoting osteoblastic differentiation and osteogenic activities in osteoblasts and indirectly by inhibiting osteoclastic bone resorption through a reduced RANKL/OPG ratio in co-cultured osteoblasts and osteoclasts.
Lipopolysaccharide-Induced Nitric Oxide and Prostaglandin E2 Production Is Inhibited by Tellimagrandin II in Mouse and Human Macrophages
Authors: Lin Chun-Yu , Kao Shih-Han , Hung Ling-Chien , Chien Hsin-Ju , Wang Wen-Hung , Chang Yu-Wei , Chen Yen-Hsu
Published: April 2021

Sepsis develops from a serious microbial infection that causes the immune system to go into overdrive. The major microorganisms that induce sepsis are Gram-negative bacteria with lipopolysaccharide (LPS) in their cell walls. Nitric oxide (NO) and cyclooxygenase-2 (COX-2) are the key factors involved in the LPS-induced pro-inflammatory process. This study aimed to evaluate the effects of polyphenol Tellimagrandin II (TGII) on anti-inflammatory activity and its underlying basic mechanism in murine macrophage cell line RAW 264.7 and human monocyte-derived macrophages. Macrophages with more than 90% cell viability were found in the cytotoxicity assay under 50 μM TGII. Pre- or post-treatment with TGII significantly reduced LPS-induced inducible nitric oxide synthase (NOS2) protein and mRNA expression, reducing LPS-induced COX-2 protein. Downstream of NOS2 and COX-2, NO and prostaglandin E2 (PGE2) were significantly inhibited by TGII. Upstream of NOS2 and COX-2, phospho-p65, c-fos and phospho-c-jun were also reduced after pre-treatment with TGII. Mitogen-activated protein kinases (MAPKs) are also critical to nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) stimulation, and phospho-p38 expression was found to have been blocked by TGII. TGII efficiently reduces LPS-induced NO production and its upstream regulatory factors, suggesting that TGII may be a potential therapeutic agent for sepsis and other inflammatory diseases.
Organic Farming Practices and Shade Trees Reduce Pest Infestations in Robusta Coffee Systems in Amazonia
Authors: Piato Kevin , Subía Cristian , Pico Jimmy , Calderón Darío , Norgrove Lindsey , Lefort François
Published: April 2021

Coffee agroforestry systems could reconcile agricultural and environmental objectives. While pests and diseases can reduce yield, their interactions with shade and nutrition have been rarely researched, and are particularly lacking in perennial systems. We hypothesized that intermediate shade levels could reduce coffee pests while excess shade could favor fungal diseases. We hypothesized that organic rather than mineral fertilization would better synchronize with nutrient uptake and higher nutrient inputs would be associated with reduced pest and disease damage due to higher plant vigor, yet effects would be less obvious in shaded plots as coffee growth would be light-limited. Using three-year-old trees of Coffea canephora var. Robusta (robusta coffee) in the Ecuadorian Amazon, we compared a full-sun system with four shading methods creating different shade levels: (1) Myroxylon balsamum; (2) Inga edulis; (3) Erythrina spp.; or, (4) Erythrina spp. plus Myroxylon balsamum. Conventional farming at either (1) moderate or (2) intensified input and organic farming at (3) low or (4) intensified input were compared in a split-plot design with shade as the main plot factor and farming practice as the sub-plot factor. The infestation of the following pests and disease incidences were evaluated monthly during the dry season: brown twig beetle (Xylosandrus morigerus), coffee leaf miner (Leucoptera coffeella), coffee berry borer (Hypothenemus hampei), anthracnose disease (Colletotrichum spp.), thread blight (Pellicularia koleroga), and cercospora leaf spot (Cercospora coffeicola). Coffee berry borer and brown twig beetle infestation were both reduced by 7% in intensified organic treatments compared to intensified conventional treatments. Colonization of coffee berry borer holes in coffee berries by the entomopathogenic fungus Beauveria bassiana was also assessed. Brown twig beetle infestation was significantly higher under full sun than under Inga edulis, yet no other shade effects were detected. We demonstrate for the first time how intensified input use might promote pest populations and thus ultimately lead to robusta coffee yield losses.
Do Microplastics Enter Our Food Chain Via Root Vegetables? A Raman Based Spectroscopic Study on Raphanus sativus
Authors: Tympa Leda-Eleni , Katsara Klytaimnistra , Moschou Panagiotis N. , Kenanakis George , Papadakis Vassilis M.
Published: April 2021

The outburst of plastic pollution in terrestrial ecosystems poses a potential threat to agriculture and food safety. Studies have already provided evidence for the uptake of plastic microparticles by several plant species, accompanied by numerous developmental effects, using fluorescence labelling techniques. Here, we introduce the implementation of confocal Raman spectroscopy, a label-free method, for the effective detection of microplastics (MPs) accumulation in the roots of a common edible root vegetable plant, Raphanus sativus, after treatment with acrylonitrile butadiene styrene (ABS) powder. We also demonstrate the concomitant occurrence of phenotypic defects in the polymer-treated plants. We anticipate that this work can provide new insights not only into the extent of the impact this widespread phenomenon has on crop plants but also on the methodological requirements to address it.
Development and Processing of Continuous Flax and Carbon Fiber-Reinforced Thermoplastic Composites by a Modified Material Extrusion Process
Authors: Kuschmitz Sebastian , Schirp Arne , Busse Johannes , Watschke Hagen , Schirp Claudia , Vietor Thomas
Published: April 2021

Additive manufacturing, especially material extrusion (MEX), has received a lot of attention recently. The reasons for this are the numerous advantages compared to conventional manufacturing processes, which result in various new possibilities for product development and -design. By applying material layer by layer, parts with complex, load-path optimized geometries can be manufactured at neutral costs. To expand the application fields of MEX, high-strength and simultaneously lightweight materials are required which fulfill the requirements of highly resilient technical parts. For instance, the embedding of continuous carbon and flax fibers in a polymer matrix offers great potential for this. To achieve the highest possible variability with regard to the material combinations while ensuring simple and economical production, the fiber–matrix bonding should be carried out in one process step together with the actual parts manufacture. This paper deals with the adaptation and improvement of the 3D printer on the one hand and the characterization of 3D printed test specimens based on carbon and flax fibers on the other hand. For this purpose, the print head development for in-situ processing of contin uous fiber-reinforced parts with improved mechanical properties is described. It was determined that compared to neat polylactic acid (PLA), the continuous fiber-reinforced test specimens achieve up to 430% higher tensile strength and 890% higher tensile modulus for the carbon fiber reinforcement and an increase of up to 325% in tensile strength and 570% in tensile modulus for the flax fibers. Similar improvements in performance were achieved in the bending tests.
An Exploratory Study on Resistance Spot Welding of Titanium Alloy Ti-6Al-4V
Authors: Fatmahardi Ichwan , Mustapha Mazli , Ahmad Azlan , Derman Mohd Nazree , Lenggo Ginta Turnad , Taufiqurrahman Iqbal
Published: April 2021

Resistance spot welding (RSW) is one of the most effective welding methods for titanium alloys, in particular Ti-6Al-4V. Ti-6Al-4V is one of the most used materials with its good ductility, high strength, weldability, corrosion resistance, and heat resistance. RSW and Ti-6Al-4V materials are often widely used in industrial manufacturing, particularly in automotive and aerospace industries. To understand the phenomenon of resistance spot weld quality, the physical and mechanical properties of Ti-6Al-4V spot weld are essential to be analyzed. In this study, an experiment was conducted using the Taguchi L9 method to find out the optimum level of the weld joint strength. The given optimum level sample was analyzed to study the most significant affecting RSW parameter, the failure mode, the weld nugget microstructure, and hardness values. The high heat input significantly affect the weld nugget temperature to reach and beyond the β-transus temperature. It led to an increase in the weld nugget diameter and the indentation depth. The expulsion appeared in the high heat input and decreased the weld nugget strength. It was caused by the molten material ejection in the fusion zone. The combination of high heat input and rapid air cooling at room temperature generated a martensite microstructure in the fusion zone. It increased the hardness, strength, and brittleness but decreased the ductility.
Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision
Authors: Lim Sunghyun , Ji Yong-hyeon , Park Yeong-il
Published: April 2021

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.
Envy-Free Allocation by Sperner’s Lemma Adapted to Rotation Shifts in a Company
Authors: Lantarón Sagrario , López Mariló , Merchán Susana , Rodrigo Javier , Rodríguez José Samuel
Published: April 2021

This article discusses a theoretical construction based on the graph theory to rework the space of potential partitions in envy-free distribution. This work has the objective of applying Sperner’s lemma to the distribution of three rotating shifts for three workers who are to cover a 24 h job position in a company. As a novel feature, worker’s preferences have been modeled as functions of probability for the three shifts, according to salary offers for said shifts. Envy-free allocation was achieved, since each worker received their preferred shift without the need for negotiation between agents in conflict. Adaptation to the type of dynamic situations that arise with rotating shifts, as well as the consideration of probabilistic preferences by workers are some of the main novelties of this work.
Real-Valued Systemic Risk Measures
Authors: Doldi Alessandro , Frittelli Marco
Published: April 2021

We describe the axiomatic approach to real-valued Systemic Risk Measures, which is a natural counterpart to the nowadays classical univariate theory initiated by Artzner et al. in the seminal paper “Coherent measures of risk”, Math. Finance, (1999). In particular, we direct our attention towards Systemic Risk Measures of shortfall type with random allocations, which consider as eligible, for securing the system, those positions whose aggregated expected utility is above a given threshold. We present duality results, which allow us to motivate why this particular risk measurement regime is fair for both the single agents and the whole system at the same time. We relate Systemic Risk Measures of shortfall type to an equilibrium concept, namely a Systemic Optimal Risk Transfer Equilibrium, which conjugates Bühlmann’s Risk Exchange Equilibrium with a capital allocation problem at an initial time. We conclude by presenting extensions to the conditional, dynamic framework. The latter is the suitable setup when additional information is available at an initial time.
The Structure of n Harmonic Points and Generalization of Desargues’ Theorems
Authors: Thaqi Xhevdet , Aljimi Ekrem
Published: April 2021

In this paper, we consider the relation of more than four harmonic points in a line. For this purpose, starting from the dependence of the harmonic points, Desargues’ theorems, and perspectivity, we note that it is necessary to conduct a generalization of the Desargues’ theorems for projective complete n-points, which are used to implement the definition of the generalization of harmonic points. We present new findings regarding the uniquely determined and constructed sets of H-points and their structure. The well-known fourth harmonic points represent the special case (n = 4) of the sets of H-points of rank 2, which is indicated by P42.
Philos-Type Oscillation Results for Third-Order Differential Equation with Mixed Neutral Terms
Authors: Kumar Marappan Sathish , Bazighifan Omar , Almutairi Alanoud , Chalishajar Dimplekumar N.
Published: April 2021

The motivation for this paper is to create new Philos-type oscillation criteria that are established for third-order mixed neutral differential equations with distributed deviating arguments. The key idea of our approach is to use the triple of the Riccati transformation techniques and the integral averaging technique. The established criteria improve, simplify and complement results that have been published recently in the literature. An example is also given to demonstrate the applicability of the obtained conditions.
The Impact of Increased Fib-4 Score in Patients with Type II Diabetes Mellitus on COVID-19 Disease Prognosis
Authors: Calapod Ovidiu P. , Marin Andreea M. , Onisai Minodora , Tribus Laura C. , Pop Corina S. , Fierbinteanu-Braticevici Carmen
Published: April 2021

Background: Emerging evidence suggests that patients with metabolic (dysfunction) associated fatty liver disease (MAFLD) are prone to severe forms of coronavirus disease (COVID-19), especially those with underlying liver fibrosis. The aim of our study is to assess the association of an increased FIB-4 score with COVID-19 disease prognosis. Methods: We performed a prospective study on hospitalized patients with known type II diabetes mellitus (T2DM) and confirmed COVID-19, with imaging evidence of liver steatosis within the last year or known diagnosis of MAFLD. All individuals were screened for liver fibrosis with a FIB-4 index. We evaluated the link between FIB-4 and disease prognosis. Results: Of 138 participants, 91.3% had MAFLD and 21.5% patients had a high risk of fibrosis. In the latter group of patients, the number of severe forms of disease, the hospital stay length, the rate of ICU admissions and the number of deaths reported registered a statistically significant increase. The independent predictors for developing severe forms of COVID-19 were obesity (odds ratio (OR), 3.24; 95% confidence interval (CI), p = 0.003), higher values of ferritin (OR-1.9; 95% CI, 1.17–8.29, p = 0.031) and of FIB-4 ≥ 3.25 (OR-4.89; 95% CI, 1.34–12.3, p = 0.02). Conclusions: Patients with high scores of FIB-4 have poor clinical outcomes and liver fibrosis may have a relevant prognostic role. Although the link between liver fibrosis and the prognosis of COVD-19 needs to be evaluated in further studies, screening for liver fibrosis with FIB-4 index, particularly in patients at risk, such as those with T2DM, will make a huge contribution to patient risk stratification.
Water Electrolysis Using a Porous IrO2/Ti/IrO2 Catalyst Electrode and Nafion Membranes at Elevated Temperatures
Authors: Kim Je-Deok , Ohira Akihiro
Published: April 2021

Porous IrO2/Ti/IrO2 catalyst electrodes were obtained by coating IrO2 on both sides of three types of porous Ti powder sheets (sample 1, sample 2, and sample 3) using different surface treatment methods, and a hydrogen evolution catalyst electrode was obtained by coating Pt/C on carbon gas diffusion layers. A Nafion115 membrane was used as an electrolyte for the membrane electrode assemblies (MEA). Water electrolysis was investigated at cell temperatures up to 150 °C, and the electrical characteristics of the three types of porous IrO2/Ti/IrO2 catalyst electrodes were investigated. The sheet resistance of sample 1 was higher than those of samples 2 and 3, although during water electrolysis, a high current density was observed due to the nanostructure of the IrO2 catalyst. In addition, the structural stabilities of Nafion and Aquivion membranes up to 150 °C were investigated by using small angle X-ray scattering (SAXS). The polymer structures of Nafion and Aquivion membranes were stable up to 80 °C, whereas the crystalline domains grew significantly above 120 °C. In other words, the initial polymer structure did not recover after the sample was heated above the glass transition temperature.
Effect of Asymmetric Membrane Structure on Hydrogen Transport Resistance and Performance of a Catalytic Membrane Reactor for Ethanol Steam Reforming
Authors: Bobrova Ludmilla , Eremeev Nikita , Vernikovskaya Nadezhda , Sadykov Vladislav , Smorygo Oleg
Published: April 2021

The performance of catalytic membrane reactors (CMRs) depends on the specific details of interactions at different levels between catalytic and separation parts. A clear understanding of decisive factors affecting their operational parameters can be provided via mathematical simulations. In the present paper, main results of numerical studies of ethanol steam reforming, followed by downstream hydrogen permeation through an asymmetric supported membrane, are reported. The membrane module consists of a thin selective layer supported on a substrate with graded porous structure. One-dimensional isothermal reaction–transport model for the CMR has been developed, and its validation has been carried out by using performance data from a lab-scale reactor with a disk-shaped membrane. Simulations demonstrate the model’s capabilities to analyze local concentrations gradients, as required to provide accurate estimates of the relationship between structure–property–performance. It was shown that transport properties of multilayer asymmetric membranes are highly related to the structural properties of each single layer.
Pilot Demonstration of Reclaiming Municipal Wastewater for Irrigation Using Electrodialysis Reversal: Effect of Operational Parameters on Water Quality
Authors: Xu Xuesong , He Qun , Ma Guanyu , Wang Huiyao , Nirmalakhandan Nagamany , Xu Pei
Published: April 2021

The modification of ion composition is important to meet product water quality requirements, such as adjusting the sodium adsorption ratio of reclaimed water for irrigation. Bench- and pilot-scale experiments were conducted using an electrodialysis reversal (EDR) system with Ionics normal grade ion-exchange membranes (CR67 and AR204) to treat the reclaimed water in the Scottsdale Water Campus, Arizona. The goal is to investigate the impact of operating conditions on improving reclaimed water quality for irrigation and stream flow augmentation. The desalting efficiency, expressed as electrical conductivity (EC) reduction, was highly comparable at the same current density between the bench- and pilot-scale EDR systems, proportional to the ratio of residence time in the electrodialysis stack. The salt flux was primarily affected by the current density independent of flow rate, which is associated with linear velocity, boundary layer condition, and residence time. Monovalent-selectivity in terms of equivalent removal of divalent ions (Ca2+, Mg2+, and SO42−) over monovalent ions (Na+, Cl−) was dominantly affected by both current density and water recovery. The techno-economic modeling indicated that EDR treatment of reclaimed water is more cost-effective than the existing ultrafiltration/reverse osmosis (UF/RO) process in terms of unit operation and maintenance cost and total life cycle cost. The EDR system could achieve 92–93% overall water recovery compared to 88% water recovery of the UF/RO system. In summary, electrodialysis is demonstrated as a technically feasible and cost viable alternative to treat reclaimed water for irrigation and streamflow augmentation.
Data-Driven Modeling for Multiphysics Parametrized Problems-Application to Induction Hardening Process
Authors: Derouiche Khouloud , Garois Sevan , Champaney Victor , Daoud Monzer , Traidi Khalil , Chinesta Francisco
Published: April 2021

Data-driven modeling provides an efficient approach to compute approximate solutions for complex multiphysics parametrized problems such as induction hardening (IH) process. Basically, some physical quantities of interest (QoI) related to the IH process will be evaluated under real-time constraint, without any explicit knowledge of the physical behavior of the system. Hence, computationally expensive finite element models will be replaced by a parametric solution, called metamodel. Two data-driven models for temporal evolution of temperature and austenite phase transformation, during induction heating, were first developed by using the proper orthogonal decomposition based reduced-order model followed by a nonlinear regression method for temperature field and a classification combined with regression for austenite evolution. Then, data-driven and hybrid models were created to predict hardness, after quenching. It is shown that the results of artificial intelligence models are promising and provide good approximations in the low-data limit case.
Inelastic Strength for Fire Resistance of Composite I-Beam Covered by Insulation Material Subjected to Basic Loading Condition
Authors: Nguyen Xuan Tung , Park Jong Sup
Published: April 2021

This paper presents a nonlinear numerical study on the moment resistance of composite steel-concrete beam using fire insulation subjected to various fire scenarios and basic loading conditions. The temperature-dependent material properties of fire insulation, concrete and steel were taken into consideration. The nonlinear finite element analysis was done by utilizing a commercial finite element program, ABAQUS. The obtained moment capacity of the composite I-beam from the current fire code was also performed and compared. The results showed that the fire scenarios and the fire insulation thickness have a great influence on the temperature distribution and strength degradation of the composite beam. The capacity of the beam in hydrocarbon fires, which is the most severe scenario, decreases faster than that in ISO834 standard fire and external fire. The fire resistance of the beam increases as the fire insulation thickness increases due to the temperature degradation in the steel beam. The calculated results from the current fire codes give conservative value at normal temperature and low temperature. The current fire codes can give unconservative values at high temperature when there is a great temperature discrepancy between parts of the beam. A new factor was proposed to determine the fire moment resistance of the composite beam with non-uniform temperature.
A Study on the Effect of Alumina on the Morphology and Reduction Behavior of Sinter by In Situ Observation
Authors: Shin Sang Gyun , Kim Wan Ho , Min Dong Joon
Published: April 2021

The effects of Al2O3 content on the morphology and reducibility of sinter were respectively investigated using confocal laser microscopy and thermogravimetric analysis at 1273 K under CO gas. To understand the effects of the sintering process, separate samples were prepared via the equilibrium and metastable reaction routes. In the equilibrium samples, the addition of Al2O3 led to the formation of the silico-ferrite of calcium and alumino phase and a decrease in the reduction rate due to the lowered reactivity of iron oxide. In contrast, in the metastable samples, the reduction rate increased after the addition of 2.5 mass% Al2O3. The addition of Al2O3 decreased the fraction of the liquid phase and increased the fraction of pores in the sample. As a result, the reduction rate is proportional to the Al2O3 content owing to the changes in the sinter morphology. In determining the reduction rate of the sinter, the influence of the microstructure on the diffusion of the reducing gas is more significant than that of the interfacial chemical reaction due to the formation of the SFCA phase. The microstructure changes of the sinter with the addition of Al2O3 and the corresponding reduction behaviors are further discussed.
Composition Stability and Cr-Rich Phase Formation in W-Cr-Y and W-Cr-Ti Smart Alloys
Authors: Sobieraj Damian , Wróbel Jan S. , Gilbert Mark R. , Litnovsky Andrey , Klein Felix , Kurzydłowski Krzysztof J. , Nguyen-Manh Duc
Published: April 2021

W-Cr-Y smart alloys are potential material candidates for plasma facing components due to their protective behaviour during the loss-of-coolant accident (LOCA), while maintaining beneficial properties of W during the normal operation of the fusion power plant. During plasma exposure, the lighter alloying elements are preferentially sputtered at the surface, but in case of a LOCA, the plasma quenches and sputtering stops and diffusion of the alloying elements to the surface becomes intensive. The diffusion of Cr to the surface due to alloying elements (Y, Ti) yields a protective oxide layer stopping the sublimation of WO3. The phase stability and short-range ordering of ternary alloys in W-Cr-Y(Ti) systems has been investigated, using combination of Density Functional Theory (DFT) and Cluster Expansion (CE) methods with Monte-Carlo (MC) simulations. It has been found out from the DFT calculations, that all pairs in the W-Cr-Y system have positive values of the enthalpy of mixing, while most of the Cr-Ti and Ti-W binary structures have negative enthalpies of mixing. The shift in the short-range order as a function of temperature between Cr and W has been predicted as a result of Y addition in W-Cr-Y alloys compared to W70Cr30, by around 400 K towards lower temperatures. A strong tendency towards clustering of Y has been observed even at elevated temperatures (1800 K). The decrease of the order–disorder transition temperature (ODTT) as a result of the Y addition has been observed, while the addition of Ti has not shown any significant changes in the ordering of W-Cr-Ti alloys compared to W-Cr alloy. Our MC simulations showed that for the W70Cr29Y1 alloy the enthalpy of mixing (Hmix) value is positive in the whole analysed temperature range. Free energy of mixing above 1000 K has been calculated from the first nearest neighbours approximation for W70Cr29Y1 and W70Cr29Ti1 alloys. The results of the present investigations provide an insight enabling for optimizing chemical composition of materials for future plasma facing components.