bluuebunny/crossref_metadata_2025 huggingface dataset:
LPS Induces Opposing Memory-like Inflammatory Responses in Mouse Bone Marrow Neutrophils
Authors: Lajqi Trim , Braun Maylis , Kranig Simon , Frommhold David , Pöschl Johannes , Hudalla Hannes
Published: September 2021

A growing body of evidence suggests that innate immune cells can respond in a memory-like (adaptive) fashion, which is referred to as trained immunity. Only few in vivo studies have shown training effects in neutrophils; however, no in vitro setup has been established to study the induction of trained immunity or tolerance in neutrophils by microbial agents. In light of their short lifespan (up to 48 h), we suggest to use the term trained sensitivity for neutrophils in an in vitro setting. Here, we firstly describe a feasible two-hit model, using different doses of lipopolysaccharide (LPS) in bone marrow neutrophils. We found that low doses (10 pg/mL) induce pro-inflammatory activation (trained sensitivity), whereas priming with high doses (100 ng/mL) leads to suppression of pro-inflammatory mediators such as TNF-α or IL-6 (tolerance) (p < 0.05). On a functional level, trained neutrophils displayed increased phagocytic activity and LFA-1 expression as well as migrational capacity and CD11a expression, whereas tolerant neutrophils show contrasting effects in vitro. Mechanistically, TLR4/MyD88/PI3Ks regulate the activation of p65, which controls memory-like responses in mouse bone marrow neutrophils (p < 0.05). Our results open a new window for further in vitro studies on memory-like inflammatory responses of short-lived innate immune cells such as neutrophils.
Real-World Outcomes Using a Spinal Cord Stimulation Device Capable of Combination Therapy for Chronic Pain: A European, Multicenter Experience
Authors: Kallewaard Jan , Paz-Solis Jose , De Negri Pasquale , Canós-Verdecho Maria , Belaid Hayat , Thomson Simon , Abejón David , Vesper Jan , Mehta Vivek , Rigoard Philippe , Maino Paolo , Love-Jones Sarah , Peña Isaac , Bayerl Simon , Perruchoud Christophe , Bougeard Renaud , Mertz Cleo , Pei Yu , Jain Roshini
Published: September 2021

Given the differing mechanisms thought to underlie therapeutic sub- and supra-perception-based neurostimulative modalities, Spinal Cord Stimulation (SCS) systems designed for combined delivery of these approaches may help improve analgesic outcomes and quality of life, and reduce treatment failures. This multicenter, observational case-series evaluated 188 patients with chronic back and/or leg pain implanted with an SCS device capable of sequential or simultaneous delivery of sub-perception and supra-perception stimulation programming (i.e., combination therapy) at 16 sites in Europe. Following implantation, patients were provided with an array of advanced supra-perception programs (e.g., paresthesia-based SCS using multiple independent current sources), and a custom set of sub-perception programs optimized with specific waveforms and/or field shapes. A mean overall pain score of 7.9 ± 1.7 (Standard Deviation (SD)) was reported pre-trial (Baseline). Overall pain was reduced by 4.4 ± 2.8 points (NRS) at 3-months (n = 117) and at 12 months post-implant (n = 90), respectively (p < 0.0001). Substantial quality-of-life (EQ-5D-5L) improvement as assessed at last follow-up was also observed (n = 60). These results suggest that an implanted SCS device capable of combination therapy, while also enabled with patient-specific waveform optimization and stimulation field targeting capabilities, can enable highly effective pain relief and improve quality of life in patients suffering with chronic pain.
Impact of COVID-19 on Eye Care in Spain during the First Phase of the Pandemic
Authors: Rodríguez-Fernández Carmen Antía , Varela-Agra María , Pérez-Roldán Lucía , Álvarez-Reguera Ana , Martínez-Reglero Cristina , Campo-Gesto Ana
Published: September 2021

Background: The declaration of the first state of alarm for COVID-19 in March 2020 provoked changes in ophthalmological care. The objective of this study was to assess its impact on reorganising care activities, the mental health of ophthalmologists and the training of residents. Methods: We sent an anonymous online questionnaire between August and October 2020 to consultant ophthalmologists and residents who were active during the state of alarm in Spain. We used Google Forms® software for data collection. We analysed responses according to the degree of regional impact. Results: We received a total of 328 responses from the 17 Autonomous Communities. We saw that 99.4% of respondents changed their work activities with 50% reductions in surgery (94.5%) and consultations (93.0%). Furthermore, 58.8% of respondents reported increased anxiety, and 29.9% transferred to support other services, with this number reaching 49.6% in the hardest-hit regions. Training programs were greatly reduced in external consultations (90.7%), and surgical training was completely cancelled (100%). Additionally, 56.5% of trainees wanted to prolong their residence periods. Conclusions: The first wave of the pandemic produced significant changes in ophthalmology services, and these changes were more pronounced in the most affected regions. It caused a negative psychological impact on a high rate of respondents and an interruption of the training of ophthalmology residents. Predictably, the negative consequences of this delay in ophthalmological care on patients will be uneven between regions.
The Impact of the COVID-19 Emergency on Life Activities and Delivery of Healthcare Services in the Elderly Population
Authors: Agrawal Siddarth , Makuch Sebastian , Dróżdż Mateusz , Strzelec Bartłomiej , Sobieszczańska Małgorzata , Mazur Grzegorz
Published: September 2021

Due to the prevailing pandemic of the coronavirus disease COVID-19, we are experiencing emotional and social isolation, which negatively affects mental and physical health, particularly among the elderly population. In this study, we performed a cross-sectional analysis based on computer-assisted telephone interviews of 500 Polish adults aged 60 years or older in order to determine the impact of the SARS-CoV-2 pandemic on the older population’s behavior, life activity, and delivery of healthcare services. According to our study, COVID-19 infection entailed a substantial change in older people’s behavior. Over 50%, nearly 80%, and more than 25% of the surveyed participants reduced their social, recreational, and professional activities, respectively. The most significant change in senior’s behavior due to the fear of COVID-19 infection was observed in patients (1) with cardiac and pulmonary problems, (2) being on multi-drug therapy, (3) vaccinated against influenza, and (4) with several mental difficulties including loneliness, social isolation, and depression. Furthermore, we demonstrated that 10% of participants canceled planned hospitalization due to the fear of COVID-19 infection. This was observed primarily in patients suffering from chronic heart and lung diseases, vaccinated against influenza, exhibiting the reluctance to carry out more complex daily activities, and with a higher level of anxiety, social loneliness, and malnutrition. Thus, these groups of seniors require more attention; hence, we propose telemedicine as a strategy directed to them that provides clinical healthcare and information regarding measurements, control, and protection against SARS-CoV-2 during the prevailing COVID-19 pandemic. We believe this strategy may improve treatment outcomes, reduce comorbidities-related complications and unnecessary hospitalizations.
TOUCH® Prosthesis for Thumb Carpometacarpal Joint Osteoarthritis: A Prospective Case Series
Authors: Froschauer Stefan M. , Holzbauer Matthias , Mihalic Julian A. , Kwasny Oskar
Published: September 2021

The dual mobility concept currently represents the newest generation of thumb carpometacarpal prostheses. The aim of this study was to evaluate the short-term outcomes of TOUCH® prosthesis. From September 2019 to July 2020, 40 prosthesis were implanted in 37 patients suffering from symptomatic stage III osteoarthritis. All included patients with a median age of 57.7 (IQR: 13.6) finished the systematic follow-up regimen (4, 8, 16 weeks, 6, and 12 months postoperatively). All parameters significantly improved (p < 0.0001) compared to the preoperative status. At 1 year follow-up, median DASH Scores decreased from 54 (IQR 22) to 12 (IQR 28) and pain levels improved from 8 (IQR 2) to 1 (IQR 2). Moreover, key-pinch strength increased from 3.8 (2.0) to 5.8 (2.5), while palmar abduction, radial abduction, and opposition also significantly improved. 35/37 patients were satisfied with the functional outcomes. We observed 10 complications, of which 6 were tendon-related issues, and 2 were due to an inappropriate choice of neck size. We could detect one dislocation but no evidence of cup loosening, tilting or subsidence in any patient. Despite the occurrence of some complications, we recommend implantation of this prosthesis type due to favorable clinical and radiological performance.
Protein Kinase A Detection in Human Urine Samples
Authors: Ragone Angela , Salzillo Alessia , Spina Annamaria , Zappavigna Silvia , Caraglia Michele , Sapio Luigi , Naviglio Silvio
Published: September 2021

Actively involved in tumor maintenance, cAMP-dependent protein kinase A (PKA) has been proposed as a putative biomarker in cancer. Recently, an active PKA form has been identified in human sera and PKA autoantibodies have been detected in cancer patients. However, their serum functions, as well as diagnostic significance, remain largely unknown. Although several PKA detection assays have been developed, none refer to a laboratory diagnostic procedure. Among these, ELISA and Western blotting (WB) assays have been employed in PKA detection. Since, to the best of our knowledge, there are no data showing its presence in human urine samples, herein, we explore the possibility of PKA’s existence in this biological specimen. Interestingly, among the 30 screened urines by quantitative sandwich ELISA, we recognized detectable PKA levels in 5 different samples, and of those two exhibited a considerable high concentration. To corroborate these results, we also evaluated PKA’s presence in both positive and negative ELISA urines by WB. Remarkably, immunoblotting analysis confirmed PKA’s existence in certain, but not in all, human urine specimens. Despite being quite preliminary, these findings firstly identify PKA in urine samples and provide evidence for its potential clinic usage as a diagnostic analyte in laboratory medicine.
Association of Flow Rate of Prehospital Oxygen Administration and Clinical Outcomes in Severe Traumatic Brain Injury
Authors: Hong Won Pyo , Hong Ki Jeong , Shin Sang Do , Song Kyoung Jun , Kim Tae Han , Park Jeong Ho , Ro Young Sun , Lee Seung Chul , Kim Chu Hyun , Jeong Joo
Published: September 2021

The goal of this study was to investigate the association of prehospital oxygen administration flow with clinical outcome in severe traumatic brain injury (TBI) patients. This was a cross-sectional observational study using an emergency medical services-assessed severe trauma database in South Korea. The sample included adult patients with severe blunt TBI without hypoxia who were treated by EMS providers in 2013 and 2015. Main exposure was prehospital oxygen administration flow rate (no oxygen, low-flow 1~5, mid-flow 6~14, high-flow 15 L/min). Primary outcome was in-hospital mortality. A total of 1842 patients with severe TBI were included. The number of patients with no oxygen, low-flow oxygen, mid-flow oxygen, high-flow oxygen was 244, 573, 607, and 418, respectively. Mortality of each group was 34.8%, 32.3%, 39.9%, and 41.1%, respectively. Compared with the no-oxygen group, adjusted odds (95% CI) for mortality in the low-, mid-, and high-flow oxygen groups were 0.86 (0.62–1.20), 1.15 (0.83–1.60), and 1.21 (0.83–1.73), respectively. In the interaction analysis, low-flow oxygen showed lower mortality when prehospital saturation was 94–98% (adjusted odds ratio (AOR): 0.80 (0.67–0.95)) and ≥99% (AOR: 0.69 (0.53–0.91)). High-flow oxygen showed higher mortality when prehospital oxygen saturation was ≥99% (AOR: 1.33 (1.01~1.74)). Prehospital low-flow oxygen administration was associated with lower in-hospital mortality compared with the no-oxygen group. High-flow administration showed higher mortality.
Impact of SARS-CoV-2 Lockdown on Glycaemic Control: A Retrospective Observational Cohort Study in a Tertiary Setting
Authors: Zechmann Stefan , Hotz Leana , Di Gangi Stefania , Baumgartl Klaus , Plate Andreas , Potlukova Eliska
Published: September 2021

We analysed the effects of Swiss national lockdown due to the COVID-19 pandemic on the glycaemic control in patients with diabetes mellitus. In a retrospective observational cohort study with observation period 16 December 2018–27 July 2020, we included tertiary care patients with diabetes and at least one glycated haemoglobin A1c (HbA1c) measurement before and after the lockdown beginning. Main outcome measure was change in HbA1c after the lockdown. We included 1078 patients (86% diabetes type 2) with a mean HbA1c of 55.63 mmol/mol (7.24%). Glycaemic control was susceptible to seasonal changes with higher mean HbA1c in winter as compared to spring (57.49 mmol/mol (7.41%) vs. 55.52 mmol/mol (7.23%), p = 0.013). The lockdown did not affect the mean HbA1c values of all patients. However, we found a higher proportion of type 2 diabetes patients with a worsening HbA1c after the lockdown as compared to the year before (32% vs. 22.9%, p = 0.02). In a mixed-model regression multivariable analysis, inappropriate alcohol intake and hypothyroidism were associated with an increase in HbA1c after the lockdown. In conclusion, the national lockdown had no effect on overall mean HbA1c values but affected a proportion of type 2 diabetes patients with worsening HbA1c, whose individual risk factors were identified.
CFD-DEM Simulation of Backflow Blockage of Deep-Sea Multistage Pump
Authors: Hu Qiong , Chen Jun , Deng Liwen , Kang Yajuan , Liu Shaojun
Published: September 2021

The multistage centrifugal pump is the critical component of mineral resources lifting in deep-sea mining. The reflux of nodules in the lifting pipe caused by the emergency pump stop can easily cause the pump to clog. In this paper, coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM co-simulations) are used to clarify the solid-liquid two-phase flow in two-stage centrifugal pumps under different particle sizes (10–20, 20–30, 30–40, 40–50 mm) with constant particle concentration. The movement and accumulation behaviour of particles in different flow fields (pipeline to pump, the first to the second pump stage) is investigated. Meanwhile, the effect of particle size and particle reflux velocity on the blockage of the flow channel in the pump was investigated. Particle accumulation in the pump was observed to determine the key factors affecting the pump’s reflux capacity. The residual mass of particles in the pump at different particle sizes was counted. Simultaneously, the percentage of residual mass of 10–20 mm particles in the pump was compared between the experiment and the simulation with an acceptable tolerance of within 10%. In addition, pressure changes in the blockage-prone section were also investigated. A comparison between experiments and simulations verifies the consistency of the trend on the pump inlet pressure when clogged with 50 mm particles. It was found that larger particles in the range of 10–30 mm can better ensure the pump’s reflux performance.
Round Robin Laboratory Testing of a Scaled 10 MW Floating Horizontal Axis Wind Turbine
Authors: Gueydon Sebastien , Judge Frances M. , O’Shea Michael , Lyden Eoin , Le Boulluec Marc , Caverne Julien , Ohana Jérémy , Kim Shinwoong , Bouscasse Benjamin , Thiebaut Florent , Day Sandy , Dai Saishuai , Murphy Jimmy
Published: September 2021

This paper documents the round robin testing campaign carried out on a floating wind turbine as part of the EU H2020 MaRINET2 project. A 1/60th scale model of a 10 MW floating platform was tested in wave basins in four different locations around Europe. The tests carried out in each facility included decay tests, tests in regular and irregular waves with and without wind thrust, and tests to characterise the mooring system as well as the model itself. For the tests in wind, only the thrust of the turbine was considered and it was fixed to pre-selected levels. Hence, this work focuses on the hydrodynamic responses of a semi-submersible floating foundation. It was found that the global surge stiffness was comparable across facilities, except in one case where different azimuth angles were used for the mooring lines. Heave and pitch had the same stiffness coefficient and periods for all basins. Response Amplitude Operators (RAOs) were used to compare the responses in waves from all facilities. The shape of the motion RAOs were globally similar for all basins except around some particular frequencies. As the results were non-linear around the resonance and cancellation frequencies, the differences between facilities were magnified at these frequencies. Surge motions were significantly impacted by reflections leading to large differences in these RAOs between all basins.
Native Endophytic Pseudomonas putida as a Biocontrol Agent against Common Bean Rust Caused by Uromyces appendiculatus
Authors: Abo-Elyousr Kamal A. M. , Abdel-Rahim Ismail R. , Almasoudi Najeeb M. , Alghamdi Sameera A.
Published: September 2021

This study aimed to evaluate the efficacy of endophytic bacterium to control common bean rust disease under greenhouse conditions. Endophytic bacterium Pseudomonas putida ASU15 was isolated from fresh asymptomatic common bean, identified using biochemical and molecular characteristics. In vitro, the inhibitory effect of different concentrations of P. putida (1 × 104, 1 × 105 and 1 × 106), as well as fungicide ortiva (0.01%) on uredospores germination of Uromyces appendiculatus were tested using water agar medium. The concentration showing the highest reduction of uredospores germination was at 1 × 106, while there was complete inhibition of uredospores germination associated with using ortiva. Scanning electron microscope exhibited the ability of P. putida cells to attack the cell wall of the fungal uredospores germ tubes of U. appendiculatus, causing obvious cell wall breakdown. The activities of chitinase, lipase, and protease produced by P. putida ASU15, in vitro, were evaluated spectrophotometrically. Chitinolytic, proteolytic, and lipolytic activities were exhibited, contributing 55.26, 3.87, and 26.12 U/mL, respectively. Under greenhouse conditions, treated plants with P. putida ASU15 (two days before pathogen inoculation or at the same time of pathogen inoculation) or fungicide reduced the disease severity, compared to the control. Applying P. putida ASU15 at the same time of pathogen inoculation showed reduction in disease severity (69.9%), higher than application before pathogen inoculation (54.9%). This study is considered the first report that demonstrates the mycoparasitic strategy of P. putida for controlling U. appendiculatus. In conclusion, our results revealed that P. putida ASU15 affords a significant disease reduction that may be attributed to direct suppression of pathogen spores germination.
Use of Pedotransfer Functions in the Rosetta Model to Determine Saturated Hydraulic Conductivity (Ks) of Arable Soils: A Case Study
Authors: Borek Łukasz , Bogdał Andrzej , Kowalik Tomasz
Published: September 2021

A key parameter for the design of soil drainage and irrigation facilities and for the modelling of surface runoff and erosion phenomena in land-formed areas is the saturated hydraulic conductivity (Ks). There are many methods for determining its value. In situ and laboratory measurements are commonly regarded as the most accurate and direct methods; however, they are costly and time-consuming. Alternatives can be found in the increasingly popular models of pedotransfer functions (PTFs), which can be used for rapid determination of soil hydrophysical parameters. This study presents an analysis of the Ks values obtained from in situ measurements conducted using a double-ring infiltrometer (DRI). The measurements were conducted using a laboratory permeability meter (LPM) and were estimated using five PTFs in the Rosetta program, based on easily accessible input data, i.e., the soil type, content of various grain sizes in %, density, and water content at 2.5 and 4.2 pF, respectively. The degrees of matching between the results from the PTF models and the values obtained from the in situ and laboratory measurements were investigated based on the root-mean-square deviation (RMSD), Nash–Sutcliffe efficiency (NSE), and determination coefficient (R2). The statistical relationships between the tested variables tested were confirmed using Spearman’s rank correlation coefficient (rho). Data analysis showed that in situ measurements of Ks were only significantly correlated with the laboratory tests conducted on intact samples; the values obtained in situ were much higher. The high sensitivity of Ks to biotic and abiotic factors, especially in the upper soil horizons, did not allow for a satisfactory match between the values from the in situ measurements and those obtained from the PTFs. In contrast, the laboratory measurements, showed a significant correlation with the Ks values, as estimated by the models PTF-2 to PTF-5; the best match was found for PTF-2.
Understanding Grass Invasion, Fire Severity, and Acacia koa Regeneration for Forest Restoration in Hawaiʻi Volcanoes National Park
Authors: Hamilton Natalia P. , Yelenik Stephanie G. , Durboraw Tara D. , Cox Robert D. , Gill Nathan S.
Published: September 2021

With invasive grasses increasing wildfire occurrence worldwide, a better understanding of the relationships between native plants, fire, and invasive grass is needed to help restoration plans facilitate ecosystem resilience. Invasive grasses are particularly problematic for altering fire regimes in the tropics, yet in Hawaiʻi, restoration sites are often planted with monocultures of the native tree Acacia koa, which can promote grass growth via nitrogen fixation. This, combined with the difficulty of estimating pre-fire grass cover under thick canopies, complicates attempts to restore Hawaiian ecosystems. We studied the 2018 Keauhou Ranch Fire in Hawaiʻi to investigate three questions: (1) at what level of precision can pre-fire grass cover be accurately estimated from oblique aerial photos? (2) how are post-fire A. koa regeneration densities affected by fire severity? and (3) how are post-fire A. koa regeneration densities affected by pre-fire grass cover and its interaction with fire severity? We collected burn severity and post-fire regeneration data from 30 transects stratified across mid-elevation woodland, montane woodland, and montane shrubland communities. We evaluated visual estimates of pre-fire grass cover from oblique aerial imagery with quantitative in situ data from 60 unburned transects of the same cover types. Pre-fire estimates of grass cover categories were 67% accurate in montane woodland (n = 9) and 100% accurate in montane shrubland (n = 11), but only 20% accurate in mid-elevation woodland (n = 10). In montane woodlands with low pre-fire tree densities, A. koa regeneration densities were higher with increased fire severity, but this trend reversed when pre-fire tree densities were high. We detected no effect of pre-fire grass cover, nor its interaction with fire severity, on A. koa regeneration density. This indicates that restoration through the planting of A. koa may be successful in promoting fire-resilient A. koa forest, although there are potential issues to consider regarding the effects that A. koa’s grass promotion may have on other species within the ecosystem.
Continuous Feeding Reduces the Generation of Metabolic Byproducts and Increases Antibodies Expression in Chinese Hamster Ovary-K1 Cells
Authors: Xiao Shang , Ahmed Waqas , Mohsin Ali , Guo Meijin
Published: September 2021

Chinese hamster ovary (CHO) cells are the most important host system used for monoclonal antibody (mAb) expression. Moreover, the fed-batch culture mode is the most widely used method to increase mAb expression in CHO cells by increasing the amount of feed. However, a high amount of culture feed results in the production of metabolic byproducts. In this work, we used a continuous feeding strategy to reduce metabolic byproducts and improve mouse–human chimeric anti-epidermal growth factor receptor vIII (EGFRvIII) antibody C12 expression in Chinese hamster ovary-K1 cells. Moreover, the effects of the feeding strategy on the cell culture and monoclonal antibody production were evaluated in chemically defined suspension cultures of recombinant CHO-K1 cells. Compared with bolus feeding methods, the continuous feeding method did not have any advantages when the feeding amount was low, but with a high feeding amount, the continuous feeding method significantly reduced the concentrations of lactate and NH4+ in the later culture stage. At the end of the culture stage, compared with bolus feeding methods, the lactate and NH4+ concentrations under the continuous feeding mode were reduced by approximately 45% and 80%, respectively. In addition, the antibody C12 expression level was also increased by almost 10%. Compared to the bolus feeding method, the antibody C12 produced by the continuous feeding method had a lower content of high-mannose glycoforms. Further analysis found that the osmolality of the continuous feeding method was lower than that of the typical fed-batch bolus feeding method. Conclusively, these results indicate that the continuous feeding method is very useful for reducing metabolic byproducts and achieving higher levels of mAb production.
Metabolism of Photosynthetic Organisms
Authors: Savchenko Tatyana , Frolov Andrej
Published: September 2021

According to multiple definitions of life, metabolism is an indispensable characteristic of living organisms [...]
Prediction of Epitaxial Grain Growth in Single-Track Laser Melting of IN718 Using Integrated Finite Element and Cellular Automaton Approach
Authors: Ansari Dezfoli Amir Reza , Lo Yu-Lung , Raza M. Mohsin
Published: September 2021

The mechanical properties of selective laser melting (SLM) components are fundamentally dependent on their microstructure. Accordingly, the present study proposes an integrated simulation framework consisting of a three-dimensional (3D) finite element model and a cellular automaton model for predicting the epitaxial grain growth mode in the single-track SLM processing of IN718. The laser beam scattering effect, melt surface evolution, powder volume shrinkage, bulk heterogeneous nucleation, epitaxial growth, and initial microstructure of the substrate are considered. The simulation results show that during single-track SLM processing, coarse epitaxial grains are formed at the melt–substrate interface, while fine grains grow at the melt–powder interface with a density determined by the intensity of the heat input. During the solidification stage, the epitaxial grains and bulk nucleated grains grow toward the top surface of the melt pool along the temperature gradient vectors. The rate of the epitaxial grain growth varies as a function of the orientation and size of the partially melted grains at the melt–substrate boundary, the melt pool size, and the temperature gradient. This is observed that by increasing heat input from 250 J/m to 500 J/m, the average grain size increases by ~20%. In addition, the average grain size reduces by 17% when the initial substrate grain size decreases by 50%. In general, the results show that the microstructure of the processed IN718 alloy can be controlled by adjusting the heat input, preheating conditions, and initial substrate grain size.
Influence of Silica Modulus and Curing Temperature on the Strength of Alkali-Activated Volcanic Ash and Limestone Powder Mortar
Authors: Adewumi Adeshina Adewale , Mohd Ariffin Mohd Azreen , Maslehuddin Mohammed , Yusuf Moruf Olalekan , Ismail Mohammad , Al-Sodani Khaled A. Alawi
Published: September 2021

This present study evaluates the effect of silica modulus (Ms) and curing temperature on strengths and the microstructures of binary blended alkali-activated volcanic ash and limestone powder mortar. Mortar samples were prepared using mass ratio of combined Na2SiO3(aq)/10 M NaOH(aq) of 0.5 to 1.5 at an interval of 0.25, corresponding to Ms of 0.52, 0.72, 0.89, 1.05 and 1.18, respectively, and sole 10 M NaOH(aq). Samples were then subjected to ambient room temperature, and the oven-cured temperature was maintained from 45 to 90 °C at an interval of 15 °C for 24 h. The maximum achievable 28-day strength was 27 MPa at Ms value of 0.89 cured at 75 °C. Samples synthesised with the sole 10 M NaOH(aq) activator resulted in a binder with a low 28-day compressive strength (15 MPa) compared to combined usage of Na2SiO3(aq)/10 M NaOH(aq) activators. Results further revealed that curing at low temperatures (25 °C to 45 °C) does not favour strength development, whereas higher curing temperature positively enhanced strength development. More than 70% of the 28-day compressive strength could be achieved within 12 h of curing with the usage of combined Na2SiO3(aq)/10 M NaOH(aq). XRD, FTIR and SEM + EDX characterisations revealed that activation with combined Na2SiO3(aq)/10 M NaOH(aq) leads to the formation of anorthite (CaAl2Si2O8), gehlenite (CaO.Al2O3.SiO2) and albite (NaAlSi3O8) that improve the amorphosity, homogeneity and microstructural density of the binder compared to that of samples synthesised with sole 10 M NaOH(aq).
Finite Element Analysis of Lightning Damage Factors Based on Carbon Fiber Reinforced Polymer
Authors: Zhu Yansong , Ming Yueke , Wang Ben , Duan Yugang , Xiao Hong , Zhang Chenping , Sun Jinru , Tian Xiangyu
Published: September 2021

While carbon-fiber-reinforced polymers (CFRPs) are widely used in the aerospace industry, they are not able to disperse current from lightning strikes because their conductivity is relatively low compared to metallic materials. As such, the undispersed current can cause the vaporization or delamination of the composites, threatening aircraft safety. In this paper, finite element models of lightning damage to CFRPs were established using commercial finite element analysis software, Abaqus, with the user-defined subroutines USDFLD and HEAVEL. The influences of factors such as the structural geometry, laminate sequence, and intrinsic properties of CFRPs on the degree of damage to the composites are further discussed. The results showed that when a current from lightning is applied to the CFRP surface, it mainly disperses along the fiber direction in the outermost layer. As the length of the CFRP increases, the injected current has a longer residence time in the material due to the increased current exporting distance. Consequently, larger amounts of current accumulate on the surface, eventually leading to more severe damage to the CFRP. This damage can be alleviated by increasing the thickness of the CFRP, as the greater overall resistance makes the CFRP a better insulator against the imposed current. This study also found that the damaged area increased as the angle between the first two layers increased, whereas the depth of the damage decreased due to the current dispersion between the first two layers. The analysis of the electrical conductivity of the composite suggested that damage in the fiber direction will be markedly reduced if the conductivity in the vertical fiber direction increases approximately up to the conductivity of the fiber direction. Moreover, increasing the thermal conductivity along the fiber direction will accelerate the heat dissipation process after the lightning strike, but the influence of the improved thermal conductivity on the extent of the lightning damage is less significant than that of the electrical conductivity.
High Temperature Dry Tribological Behavior of Nb-Microalloyed Bearing Steel 100Cr6
Authors: Zhu Yucheng , Li Jian , Zhang Chaolei , Wang Wenjun , Wang Huan
Published: September 2021

100Cr6 steel is one of the most widely used bearing steels and a representative of first-generation bearing steel. Many engineering applications require rolling bearings to run at a high temperature. Therefore, it is necessary to improve the high temperature properties of 100Cr6 steel. In this paper, the effect of Nb on high temperature dry tribological behavior, including worn surface and friction coefficient, was analyzed by a wear test when Nb content was 0.018% and 0.040%. The results show that the microstructure is refined gradually, the hardness is improved, and wear volume decreases by 31.8% at most with the increase of Nb content. At 50 °C, the friction coefficient of 100Cr6 steel can be reduced by adding a small amount of Nb, but this effect will be weakened if the content of Nb is too high. In addition, excess Nb increases the hard precipitation of NbC, which aggravates the abrasive wear and leads to the increase in the depth of the worn surface. At 125 °C, the effect of Nb on tribological properties is weaker. With the increase of temperature, the steel substrate softens, and the oxide particles increase, which aggravates the abrasive wear and oxidation wear and makes the wear volume increase significantly.
Adaptive Finite Element Model for Simulating Crack Growth in the Presence of Holes
Authors: Alshoaibi Abdulnaser M. , Fageehi Yahya Ali
Published: September 2021

This study presents a developed finite element code written by Visual Fortran to computationally model fatigue crack growth (FCG) in arbitrary 2D structures with constant amplitude loading, using the linear elastic fracture mechanics (LEFM) concept. Accordingly, optimizing an FCG analysis, it is necessary to describe all the characteristics of the 2D model of the cracked component, including loads, support conditions, and material characteristics. The advancing front method has been used to generate the finite element mesh. The equivalent stress intensity factor was used as the onset criteria of crack propagation, since it is the main significant parameter that must be precisely predicted. As such, a criterion premised on direction (maximum circumferential stress theory) was implemented. After pre-processing, the analysis continues with incremental analysis of the crack growth, which is discretized into short straight segments. The adaptive mesh finite element method was used to perform the stress analysis for each increment. The displacement extrapolation technique was employed at each crack extension increment to compute the SIFs, which are then assessed by the maximum circumferential stress theory to determine the direction of the crack growth and predict the fatigue life as a function of crack length using a modified form of Paris’ law. The application examples demonstrate the developed program’s capability and performance.
Efficiency Evaluation of Regional Environmental Management Systems in Russia Using Data Envelopment Analysis
Authors: Ratner Svetlana , Lychev Andrey , Rozhnov Aleksei , Lobanov Igor
Published: September 2021

The concept of eco-efficiency has recently become an issue of great importance due to the growing trend of environmental degradation, and many approaches based on Data Envelopment Analysis (DEA) are used in the literature to evaluate the environmental performance of economic systems. However, research to date has paid little attention to the possibility of extending the DEA approach to the problem of measuring the economic feasibility of eco-efficiency improvement. The main aim of this study is to evaluate the efficiency of investments focused on improving the eco-efficiency of the regional economy in Russia using the DEA approach. The various types of costs for environmental protection measures are considered as inputs and the annual decrease in specific environmental impacts of the regional economy are considered as outputs of DEA models. This is different from previous research, which generally focused on environmental efficiency only, omitting the integration of economic aspects in eco-efficiency measures. This study compares three different modifications of basic DEA models in the context of technical complexity and practical feasibility. The results show that the efficiency of regional environmental management in many Russian regions has a great potential for improvement. From a practical point of view, the Slack-Based Measure (SBM) model provides the most accurate results for policy applications. Unlike other ratings, the DEA-SBM model may stimulate an optimization of environmental protection spending and the introduction of technological and organizational eco-innovations.
On the Use of Copula for Quality Control Based on an AR(1) Model
Authors: Young Timothy M. , Nanthakumar Ampalavanar , Nanthakumar Hari
Published: September 2021

Manufacturing for a multitude of continuous processing applications in the era of automation and ‘Industry 4.0’ is focused on rapid throughput while producing products of acceptable quality that meet customer specifications. Monitoring the stability or statistical control of key process parameters using data acquired from online sensors is fundamental to successful automation in manufacturing applications. This study addresses the significant problem of positive autocorrelation in data collected from online sensors, which may impair assessment of statistical control. Sensor data collected at short time intervals typically have significant autocorrelation, and traditional statistical process control (SPC) techniques cannot be deployed. There is a plethora of literature on techniques for SPC in the presence of positive autocorrelation. This paper contributes to this area of study by investigating the performance of ‘Copula’ based control charts by assessing the average run length (ARL) when the subsequent observations are correlated and follow the AR(1) model. The conditional distribution of yt given yt−1 is used in deriving the control chart limits for three different categories of Copulas: Gaussian, Clayton, and Farlie-Gumbel-Morgenstern Copulas. Preliminary results suggest that the overall performance of the Clayton Copula and Farlie-Gumbel-Morgenstern Copula is better compared to other Archimedean Copulas. The Clayton Copula is the more robust with respect to changes in the process standard deviation as the correlation coefficient increases.
Mathematical Modelling of Glioblastomas Invasion within the Brain: A 3D Multi-Scale Moving-Boundary Approach
Authors: Suveges Szabolcs , Hossain-Ibrahim Kismet , Steele J. Douglas , Eftimie Raluca , Trucu Dumitru
Published: September 2021

Brain-related experiments are limited by nature, and so biological insights are often limited or absent. This is particularly problematic in the context of brain cancers, which have very poor survival rates. To generate and test new biological hypotheses, researchers have started using mathematical models that can simulate tumour evolution. However, most of these models focus on single-scale 2D cell dynamics, and cannot capture the complex multi-scale tumour invasion patterns in 3D brains. A particular role in these invasion patterns is likely played by the distribution of micro-fibres. To investigate the explicit role of brain micro-fibres in 3D invading tumours, in this study, we extended a previously introduced 2D multi-scale moving-boundary framework to take into account 3D multi-scale tumour dynamics. T1 weighted and DTI scans are used as initial conditions for our model, and to parametrise the diffusion tensor. Numerical results show that including an anisotropic diffusion term may lead in some cases (for specific micro-fibre distributions) to significant changes in tumour morphology, while in other cases, it has no effect. This may be caused by the underlying brain structure and its microscopic fibre representation, which seems to influence cancer-invasion patterns through the underlying cell-adhesion process that overshadows the diffusion process.
Use of Sertraline in Hemodialysis Patients
Authors: Kubanek Alicja , Paul Przemysław , Przybylak Mateusz , Kanclerz Katarzyna , Rojek Jakub Jan , Renke Marcin , Bidzan Leszek , Grabowski Jakub
Published: September 2021

Depression and anxiety are the most common psychiatric disorders in end-stage renal disease (ESRD) patients treated with hemodialysis (HD) and may correlate with lower quality of life and increased mortality. Depression treatment in HD patients is still a challenge both for nephrologists and psychiatrists. The possible treatment of depressive disorders can be pharmacological and non-pharmacological. In our article, we focus on the use of sertraline, the medication which seems to be relatively safe and efficient in the abovementioned population, taking under consideration several limitations regarding the use of other selective serotonin reuptake inhibitors (SSRIs). In our paper, we discuss different aspects of sertraline use, taking into consideration possible benefits and side effects of drug administration like impact on QTc (corrected QT interval) prolongation, intradialytic hypotension (IDH), chronic kidney disease-associated pruritus (CKD-aP), bleeding, sexual functions, inflammation, or fracture risk. Before administering the medication, one should consider benefits and possible side effects, which are particularly significant in the treatment of ESRD patients; this could help to optimize clinical outcomes. Sertraline seems to be safe in the HD population when provided in proper doses. However, we still need more studies in this field since the ones performed so far were usually based on small samples and lacked placebo control.
Fatigue Improvement of Additive Manufactured Ti–TiB Material through Shot Peening
Authors: DiCecco Liza-Anastasia , Mehdi Mehdi , Edrisy Afsaneh
Published: September 2021

In this work, fatigue improvement through shot peening of an additive manufactured Ti–TiB block produced through Plasma Transferred Arc Solid Free-Form Fabrication (PTA-SFFF) was investigated. The microstructure and composition were explored through analytical microscopy techniques such as scanning and transmission electron microscopy (SEM, TEM) and electron backscatter diffraction (EBSD). To investigate the isotropic behavior within the additive manufactured Ti–TiB blocks, tensile tests were conducted in longitudinal, diagonal, and lateral directions. A consistent tensile behavior was observed for all the directions, highlighting a nearly isotropic behavior within samples. Shot peening was introduced as a postmanufacturing treatment to enhance the mechanical properties of AM specimens. Shot peening led to a localized increase in hardness at the near-surface where stress-induced twins are noted within the affected microstructure. The RBF-200 HT rotating-beam fatigue machine was utilized to conduct fatigue testing on untreated and shot-peened samples, starting at approximately 1/2 the ultimate tensile strength of the bulk material and testing within low- (<105 cycles) to high-cycle (>105 cycles) regimes. Shot-peened samples experienced significant improvement in fatigue life, increasing the fitted endurance limit from 247.8 MPa for the untreated samples to 318.3 MPa, leading to an increase in fatigue resistance of approximately 28%.
Modelling of Microstructure Formation in Metal Additive Manufacturing: Recent Progress, Research Gaps and Perspectives
Authors: Gunasegaram Dayalan R. , Steinbach Ingo
Published: September 2021

Microstructures encountered in the various metal additive manufacturing (AM) processes are unique because these form under rapid solidification conditions not frequently experienced elsewhere. Some of these highly nonequilibrium microstructures are subject to self-tempering or even forced to undergo recrystallisation when extra energy is supplied in the form of heat as adjacent layers are deposited. Further complexity arises from the fact that the same microstructure may be attained via more than one route—since many permutations and combinations available in terms of AM process parameters give rise to multiple phase transformation pathways. There are additional difficulties in obtaining insights into the underlying phenomena. For instance, the unstable, rapid and dynamic nature of the powder-based AM processes and the microscopic scale of the melt pool behaviour make it difficult to gather crucial information through in-situ observations of the process. Therefore, it is unsurprising that many of the mechanisms responsible for the final microstructures—including defects—found in AM parts are yet to be fully understood. Fortunately, however, computational modelling provides a means for recreating these processes in the virtual domain for testing theories—thereby discovering and rationalising the potential influences of various process parameters on microstructure formation mechanisms. In what is expected to be fertile ground for research and development for some time to come, modelling and experimental efforts that go hand in glove are likely to provide the fastest route to uncovering the unique and complex physical phenomena that determine metal AM microstructures. In this short Editorial, we summarise the status quo and identify research opportunities for modelling microstructures in AM. The vital role that will be played by machine learning (ML) models is also discussed.
Investigation of Fatigue Crack Growth in Full-Scale Railway Axles Subjected to Service Load Spectra: Experiments and Predictive Models
Authors: Pourheidar Amir , Patriarca Luca , Beretta Stefano , Regazzi Daniele
Published: September 2021

In this paper, a series of experimental investigations was performed on full-scale railway axles to analyze the fatigue crack growth behavior of EA4T steel under load spectrum derived from real operating conditions. The experimental results were compared to life predictions carried out adopting two models: (i) the conventional Nasgro equation and (ii) the cyclic R-curve concept implemented in the Modified Nasgro equation for describing the crack growth behavior of an arbitrary crack length. The results show that the life predictions performed by means of the Modified Nasgro equation coincide well with the experimental results with an underestimation of the residual lifetime less than 32%, while the traditional Nasgro equation leads to significant overestimation (≈120%) of the residual lifetime for load spectra close to the in service scenario.