bluuebunny/crossref_metadata_2025 huggingface dataset:
Return to Sport after Adolescent Idiopathic Scoliosis (AIS) Correction Surgery: A Retrospective Data Analysis
Authors: Pepke Wojciech , Madathinakam Abhilash , Bruckner Tom , Renkawitz Tobias , Hemmer Stefan , Akbar Michael
Published: February 2023

Sports are relevant to younger populations in society. Adolescent idiopathic scoliosis (AIS) patients who undergo surgical correction of the spine are often intensively involved in sports. For that, returning to the sport is often an important concern for the patients and their families. To the best of our knowledge, there is still a lack of scientific data indicating established recommendations about the time of returning to sport activities after surgical spinal correction. The aim of this study was to investigate (1) when AIS patients return to athletic activities after a posterior fusion, and (2) if they change their activities postoperatively. Furthermore, another question was (3) if the length of the performed posterior fusion or (4) fusion to the lower lumbar spine could have an influence on the rates or time of returning to sport activities postoperatively. Data collection was performed using questionnaires assessing patients’ contentment and athletic activity. Athletic activities were categorized into three categories: (1) contact, (2) contact/non-contact and (3) non-contact sports. The intensity of exercised sports, the time of returning to the sport and changes in sport habits were documented. Radiographs were evaluated pre- and postoperatively to determine the Cobb angle and the length of the posterior fusion via the identification of the upper (UIV) and lower instrumented vertebra (LIV). Stratification analysis due to the fusion length was performed to answer a hypothetical question. This retrospective survery of 113 AIS patients treated with a posterior fusion revealed that, on average, returning to sport activities required 8 months of postoperative rest. The preoperative to postoperative rate of patients participating in sport activities increased from 88 (78%) to 94 (89%). Furthermore, postoperatively, a relevant shift of exercised activities from contact to non-contact sports was noted. Further subanalysis revealed that only 33 subjects were able to return to exactly the same athletic activities as before surgery (10 months postoperatively). The assessment of radiographs revealed that in this study group, the length of the performed posterior fusion and fusions to the lower lumbar spine had no influence on the time of return to athletic activities. The results of this study might shed some light on postoperative recommendations for sport activities after AIS treatment with a posterior fusion and may be beneficial for surgeons treating patients.
Allopregnanolone Is Associated with a Stress-Induced Reduction of Heart Rate Variability in Premenstrual Dysphoric Disorder
Authors: Hamidovic Ajna , Davis John , Soumare Fatimata , Naveed Aamina , Ghani Yaseen , Semiz Selma , Khalil Dina , Wardle Margaret
Published: February 2023

Human survival and wellbeing require appropriate responses to stress, including a highly coordinated and efficient nervous system control of the heart rhythm. During stress, a greater disinhibition of the vagal nerve is reflective of poor stress adaptability, which may be relevant in premenstrual dysphoric disorder (PMDD)—a debilitating affective condition thought to be marked by dysregulated stress processing and sensitivity to allopregnanolone. In the present study, women with PMDD (n = 17) and healthy controls (n = 18), who did not take medication, smoke, or consume illicit drugs, and who were free of other psychiatric conditions, participated in the Trier Social Stress Test, during which we measured the high frequency of the heart rate (HF-HRV) and allopregnanolone using ultra-performance liquid chromatography tandem mass spectrometry. Relative to their baseline, women who have PMDD, but not the healthy controls, experienced a reduction in HF-HRV during stress anticipation (p ≤ 0.05) and stress (p ≤ 0.01). Their recovery from stress was significantly delayed (p ≤ 0.05). Absolute peak HF-HRV change from baseline was significantly predicted by baseline allopregnanolone only in the PMDD group (p ≤ 0.01). The present study shows how an interaction between stress and allopregnanolone—which have both been separately implicated in PMDD—underlies PMDD expression.
Endogenous Catecholamine Release in COVID-19 Related Acute Respiratory Distress Syndrome: Link between Enhanced Sympathetic Stimulation, Cardiac Dysfunction and Outcome
Authors: Dammassa Valentino , Voltini Marta , Colombo Costanza Natalia Julia , Siano Gilda Maria , Lo Coco Claudia , Rizzo Vittoria , Corradi Francesco , Mojoli Francesco , Tavazzi Guido
Published: February 2023

The aim of this study was to measure the serum levels of catecholamines in patients admitted to intensive care unit (ICU) with COVID-19-related acute respiratory distress syndrome (ARDS) and describe their relation with clinical, inflammatory and echocardiographic parameters. Serum levels of endogenous catecholamines (norepinephrine, epinephrine and dopamine) were measured at ICU admission. We enrolled 71 patients consecutively admitted to ICU due to moderate to severe ARDS. 11 patients (15.5%) died during the admission in ICU. Serum levels of endogenous catecholamines were significantly elevated. Norepinephrine levels were higher in those with RV and LV systolic dysfunction, higher CRP, and higher IL-6. Patients with higher mortality rate were those with norepinephrine values ≥ 3124 ng/mL, CRP ≥ 17.2 mg/dL and IL-6 ≥ 102 pg/mL. Univariable analysis by Cox proportional hazards regression modelling showed that norepinephrine, IL-6 and CRP had the highest risk of acute mortality. Multivariable analysis showed that only norepinephrine and IL-6 retained in the model. Marked increase of serum catecholamine levels is present during acute phase of critically ill COVID-19 and it is associated with inflammatory and clinical parameters.
Clinical Characteristics and Outcomes of Patients with Acute Respiratory Failure Due to SARS-CoV-2 Interstitial Pneumonia Treated with CPAP in a Medical Intermediate Care Setting: A Retrospective Observational Study on Comparison of Four Waves
Authors: Accordino Silvia , Canetta Ciro , Bettini Greta , Corsico Federica , Ghigliazza Gabriele , Barbetta Laura , Folli Christian , Savojardo Valeria , Blasi Francesco
Published: February 2023

Background: In COVID-19 patients non-invasive-positive-pressure-ventilation (NIPPV) has held a challenging role to reduce mortality and the need for invasive mechanical ventilation (IMV). The aim of this study was to compare the characteristics of patients admitted to a Medical Intermediate Care Unit for acute respiratory failure due to SARS-CoV-2 pneumonia throughout four pandemic waves. Methods: The clinical data of 300 COVID-19 patients treated with continuous positive airway pressure (CPAP) were retrospectively analysed, from March-2020 to April-2022. Results: Non-survivors were older and more comorbid, whereas patients transferred to ICU were younger and had fewer pathologies. Patients were older (from 65 (29–91) years in I wave to 77 (32–94) in IV, p < 0.001) and with more comorbidities (from Charlson’s Comorbidity Index = 3 (0–12) in I to 6 (1–12) in IV, p < 0.001). No statistical difference was found for in-hospital mortality (33.0%, 35.8%, 29.6% and 45.9% in I, II, III and IV, p = 0.216), although ICU-transfers rate decreased from 22.0% to 1.4%. Conclusions: COVID-19 patients have become progressively older and with more comorbidities even in critical care area; from risk class analyses by age and comorbidity burden, in-hospital mortality rates remain high and are thus consistent over four waves while ICU-transfers have significantly reduced. Epidemiological changes need to be considered to improve the appropriateness of care.
An Integrated Complete Ensemble Empirical Mode Decomposition with Adaptive Noise to Optimize LSTM for Significant Wave Height Forecasting
Authors: Zhao Lingxiao , Li Zhiyang , Zhang Junsheng , Teng Bin
Published: February 2023

In recent years, wave energy has gained attention for its sustainability and cleanliness. As one of the most important parameters of wave energy, significant wave height (SWH) is difficult to accurately predict due to complex ocean conditions and the ubiquitous chaotic phenomena in nature. Therefore, this paper proposes an integrated CEEMDAN-LSTM joint model. Traditional computational fluid dynamics (CFD) has a long calculation period and high capital consumption, but artificial intelligence methods have the advantage of high accuracy and fast convergence. CEEMDAN is a commonly used method for digital signal processing in mechanical engineering, but has not yet been used for SWH prediction. It has better performance than the EMD and EEMD and is more suitable for LSTM prediction. In addition, this paper also proposes a novel filter formulation for SWH outliers based on the improved violin-box plot. The final empirical results show that CEEMDAN-LSTM significantly outperforms LSTM for each forecast duration, significantly improving the prediction accuracy. In particular, for a forecast duration of 1 h, CEEMDAN-LSTM has the most significant improvement over LSTM, with 71.91% of RMSE, 68.46% of MAE and 6.80% of NSE, respectively. In summary, our model can improve the real-time scheduling capability for marine engineering maintenance and operations.
Stability Study of Graphene Oxide-Bovine Serum Albumin Dispersions
Authors: Pérez-Piñeiro Javier , Sánchez-Cea Fernando , Arce Mariana P. , Lado-Touriño Isabel , Rojas-Cervantes María Luisa , Gilsanz María Fuencisla , Gallach-Pérez Darío , Blasco Rodrigo , Barrios-Bermúdez Niurka , Cerpa-Naranjo Arisbel
Published: February 2023

In this work, a stability study of dispersions of graphene oxide and graphene oxide functionalized with polyethylene glycol (PEG) in the presence of bovine serum albumin is carried out. First, a structural characterization of these nanomaterials is performed by scanning electron microscopy, atomic force microscopy, and ultraviolet visible spectroscopy, comparing the starting nanomaterials with the nanomaterials in contact with the biological material, i.e., bovine fetal serum. The different experiments were performed at different concentrations of nanomaterial (0.125–0.5 mg/mL) and BSA (0.01–0.04 mg/mL), at different incubation times (5–360 min), with and without PEG, and at different temperatures (25–40 °C). The SEM results show that BSA is adsorbed on the surface of the graphene oxide nanomaterial. Using UV-Vis spectrophotometry, the characteristic absorption peaks of BSA are observed at 210 and 280 nm, corroborating that the protein has been adsorbed. When the time increases, the BSA protein can be detached from the nanomaterial due to a desorption process. The stability of the dispersions is reached at a pH between 7 and 9. The dispersions behave like a Newtonian fluid with viscosity values between 1.1 and 1.5 mPa·s at a temperature range of 25 to 40 °C. The viscosity values decrease as the temperature increases.
What Role do Androgens Play in Endometrial Cancer?
Authors: Maček Petra , Molinari Nikolaus , Sobočan Monika , Knez Jure
Published: February 2023

The role of estrogens and progesterone in the development and progression of endometrial cancer is well-established, but there are very little data about the role of androgens. There are five different androgens produced in women: dehydroepiandrosterone sulphate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T) and dihydrotestosterone (DHT). The most potent hormones are T and DHT, the latter being mainly produced from T in peripheral tissues, including endometrium. Although they are considered to exert antiproliferative effects in many settings and the expression of their receptors is more often associated with a good prognosis in EC, it is still unknown in which specific settings androgens have carcinogenic or protective effects in EC.
A Semi-Automatic Approach for Holistic 3D Assessment of Temporomandibular Joint Changes
Authors: Holte Michael Boelstoft , Sæderup Henrik , Pinholt Else Marie
Published: February 2023

The literature lacks a reliable holistic approach for the three-dimensional (3D) assessment of the temporomandibular joint (TMJ) including all three adaptive processes, which are believed to contribute to the position of the mandible: (1) adaptive condylar changes, (2) glenoid fossa changes, and (3) condylar positional changes within the fossa. Hence, the purpose of the present study was to propose and assess the reliability of a semi-automatic approach for a 3D assessment of the TMJ from cone-beam computed tomography (CBCT) following orthognathic surgery. The TMJs were 3D reconstructed from a pair of superimposed pre- and postoperative (two years) CBCT scans, and spatially divided into sub-regions. The changes in the TMJ were calculated and quantified by morphovolumetrical measurements. To evaluate the reliability, intra-class correlation coefficients (ICC) were calculated at a 95% confidence interval on the measurements of two observers. The approach was deemed reliable if the ICC was good (>0.60). Pre- and postoperative CBCT scans of ten subjects (nine female; one male; mean age 25.6 years) with class II malocclusion and maxillomandibular retrognathia, who underwent bimaxillary surgery, were assessed. The inter-observer reliability of the measurements on the sample of the twenty TMJs was good to excellent, ICC range (0.71–1.00). The range of the mean absolute difference of the repeated inter-observer condylar volumetric and distance measurements, glenoid fossa surface distance measurements, and change in minimum joint space distance measurements were (1.68% (1.58)–5.01% (3.85)), (0.09 mm (0.12)–0.25 mm (0.46)), (0.05 mm (0.05)–0.08 mm (0.06)) and (0.12 mm (0.09)–0.19 mm (0.18)), respectively. The proposed semi-automatic approach demonstrated good to excellent reliability for the holistic 3D assessment of the TMJ including all three adaptive processes.
Investigation of Phenolic Compounds and Antioxidant Activity of Sorbaria pallasii (Rosaceae) Microshoots Grown In Vitro
Authors: Zheleznichenko Titiana V. , Veklich Tatiana N. , Kostikova Vera A.
Published: February 2023

Sorbaria pallasii is an endemic species of the Far East and Siberia and grows along the Goltsy altitudinal belt. Data on micropropagation and phytochemical characteristics of this plant are not available, probably because of the inaccessibility of the plant material. Morphogenesis initiation from flower buds of S. pallasii in vitro and micropropagation were performed here in the Murashige and Skoog medium supplemented with 5.0 µM 6-benzylaminopurine and 0.0–1.0 µM α-naphthylacetic acid; elongation was implemented in the same medium without the hormones. A well-growing sterile culture of S. pallasii was obtained; the number of microshoots per explant reached 5.7 ± 1.2. Phytochemical analyses of in vitro propagated S. pallasii detected 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in a water-ethanol extract from its microshoots and revealed phenolic compounds in it. The phenolic compounds that likely contribute to its biological activity are tannins (74.9 mg/g), phenolcarboxylic acids (30.8 mg/g), and catechins (13.3 mg/g). In the microshoot extract, high-performance liquid chromatography identified three catechins. Microshoots showed the highest concentration of (±)-catechin (3.03 mg/(g of absolutely dry mass; ADM)). Concentrations of epigallocatechin gallate (0.38 mg/(g of ADM)) and (−)-epicatechin (0.55 mg/(g of ADM)) were significantly lower. This study paves the way for further biotechnological and phytochemical research on S. pallasii.
“That Day Does Not Belong to Our Generation”: Komatsu Sakyō’s Affective Futurities
Authors: Posadas Baryon Tensor
Published: February 2023

Commentary that observes the frequency of the appearances of images of disaster pervades much of the discourse surrounding postwar Japanese popular culture, and especially Japanese science fiction. Against such approaches, I argue that it is more productive to read these narratives of disaster through the critical lens of the genre’s engagement with the problem of futurity. My contention then is that these narratives of disaster do not merely function as imaginative repetitions or re-enactments of past events, but also take on an anticipatory quality, affectively preparing and the ground for and pre-empting responses to future events. I examine the work of Komatsu Sakyō (1931–2011) in particular, whose writing makes for an illustrative test case for articulating the premediative dimension of disaster narratives in postwar Japanese science fiction.
On the Wear Behavior of Bush Drive Chains: Part I—Characterization of Engine Damage Processes and Development of a Model Test Setup for Pin Wear
Authors: Summer Florian , Bergmann Philipp , Grün Florian
Published: February 2023

The present work deals with the tribological characterization of the bush-pin contact in timing chains, with a particular focus on the pin wear processes and the development of a model testing technique suitable for this purpose. With the presented test methodology, both the friction and other parameters, such as contact temperatures and the electrical contact resistance between the CrN-coated pin and a steel bush equivalent could be precisely measured during the test procedure, and the input parameters, such as test load, temperature, and test frequency, could be specifically adjusted. In addition, motor components were analyzed in the present study, in order to study the damage processes of application and compare them with those of the model tests. The measured friction and wear processes on the test rig were verified using well-acknowledged design parameters, such as apparent friction energy and linear wear intensity according to Fleischer. The results demonstrated the wear process between the CrN coated spherical steel surface and the plane steel counterpart (mild smoothing wear at moderate loads, and for an advanced wear state with an exposed steel substrate, there was exposed break-outs and deformation, as well as abrasive grooving) and showed that the methodology replicated the wear processes of application and is therefore suitable for characterizing the pin wear of bush drive timing chains.
An Ultra-Thin, Triple-Band, Incident Angle-Insensitive Perfect Metamaterial Absorber
Authors: Jahan MST Ishrat , Faruque Mohammad Rashed Iqbal , Hossain Md Bellal , Abdullah Sabirin
Published: February 2023

We created an ultra-thin, triple-band incident angle-insensitive perfect metamaterial absorber (MMA) with a metallic patch and a continuous metal ground isolated by a central dielectric substrate. The top metallic patch, placed across the edges of the 0.58 mm thickness Rogers RO4003C (lossy) substrate, forms the bulk of the projected absorber’s ultra-thin layer. Nonetheless, absorption is exceedingly strong, covering C-band, X-band and K-band and reaching levels of 97.8%, 99.9%, and 99.9%, respectively, under normal and even oblique (0° to 45°) incident conditions. In chosen ranges of frequency of 6.24, 10.608, and 18.624 GHz for both TM and TE mode, the displayed Q-factors were 62.4, 17.68, and 26.61, respectively. We correspondingly calculated the RAB (relative absorption bandwidth) to evaluate absorption performance. An equivalent circuit proved its performance capabilities, indicating that it would produce a high-quality MMA from ADS software. Furthermore, the absorber’s performance has been verified in free space on a sample being tested using a different array of unit cells. Moreover, the proposed structures with HFSS simulators to display the MMA’s absolute absorption at each absorption peak are somewhat inconsistent with the results of the CST simulator. Because of its superior performance, the ultra-thin absorber is suited for a wide range of applications, including satellite applications such as radar systems, stealth technology, imaging, and electromagnetic interference reduction.
Comparative Analysis of Waste, Steel, and Polypropylene Microfibers as an Additive for Cement Mortar
Authors: Zakrzewski Mateusz , Gancarz Mateusz , Tvrdá Katarína , Laskowska-Bury Joanna , Domski Jacek
Published: February 2023

This study presents the results of laboratory experiments conducted to determine the mechanical parameters for cement mortar with various quantities of waste fibers, polypropylene microfibers, and steel microfibers. Waste fibers were used as samples and obtained using an end-of-life car tire recycling process. For comparison, samples with the addition of steel and polypropylene microfibers were tested. The same degrees of fiber reinforcement were used for all types of fibers. Ultimately, 22 mixtures of cement mortar were prepared. The aim of this study is therefore to present and compare basic mechanical parameter values. Compressive strength, flexural strength, fracture toughness, and flexural toughness were of particular interest. A three-point bending test was performed on three types of samples, without a notch and with a notch of 4 and 8 mm. The results show that the use of steel microfibers in the cement mortar produces a product with better properties compared to a mixture with steel cord or polypropylene fibers. However, the cement mortar with the steel cord provides better flexural strength and greater flexural toughness factors compared to the cement mortar with polypropylene fibers. This means that the steel cord is a full-value ecological replacement for different fibers.
Wooden Solar Evaporator Design Based on the Water Transpiration Principle of Trees
Authors: Xiong Wei , Li Dagang
Published: February 2023

The double-sided carbonization of poplar with different sections forms a three-layer structure inspired by tree water transpiration. A photothermal evaporation comparison experiment was conducted to simulate the influence of solar radiation intensity (1 kW·m−2) on uncarbonized and single- and double-sided carbonized poplar specimens. The tissue structure, chemical functional group changes, and profile density of the specimens were analyzed using scanning electron microscopy, Fourier transform infrared spectrometry, and X-ray profile density testing, respectively. The results showed that the tissue structure of the specimen changed after treatment, and the relationship of water evaporation was shown as follows: cross-section (C) > Radial section (R) > Tangential section (T), and Double-sided carbonized poplar (DCP) > Single-sided carbonized poplar (SCP) > Non-carbonized poplar (NCP). Of these, the maximum photothermal evaporation was from the cross-section of the double-sided carbonized poplar (NCPC) with a value of 1.32 kg·m−2·h−1, which was 21.97% higher than single-sided carbonized poplar (SCPC) and 37.88% higher than non-carbonized poplar (NCPC). Based on the results, double-sided carbonization three-layer structure treatment can improve the evaporation force of the poplar interface, thereby improving the moisture migration ability of wood, and can be applied to solar interface absorber materials.
Enhanced Fatigue Limit in Ultrafine-Grained Ferritic–Martensitic Steel
Authors: Nikitina Marina A. , Islamgaliev Rinat K. , Ganeev Artur V. , Frik Aleksandra A.
Published: February 2023

The influence of the ultrafine-grained (UFG) structure on the fatigue endurance limit and the nature of fatigue failure have been studied. It is shown that the formation of the UFG structure containing carbides and the coincidence site lattice relationship (CSL) and twin boundaries leads to an increase in the fatigue endurance limit. To study the mechanisms of fatigue failure, scanning and transmission electron microscopy and X-ray diffraction analysis were used. Studies have shown that the formation of the UFG structure as a result of rolling and subsequent heat treatment above the temperature of the ferrite/austenite phase transition leads to an increase in the fatigue endurance limit by more than 70%, from 475 to 800 MPa, compared to coarse-grained samples. The dynamic aging observed during fatigue tests was more pronounced in materials with a UFG microstructure. The influence of the CSL and twin boundaries on the nature of the fatigue failure of ferritic–martensitic steel is discussed.
Glass–Zirconia Composites as Seals for Solid Oxide Cells: Preparation, Properties, and Stability over Repeated Thermal Cycles
Authors: Kosiorek Magdalena , Żurawska Agnieszka , Ajdys Leszek , Kolasa Anna , Naumovich Yevgeniy , Wiecińska Paulina , Yaremchenko Aleksey , Kupecki Jakub
Published: February 2023

This study focuses on the preparation and characterization of composite gaskets designed for the sealing of the solid oxide cell stacks operating below 700 °C. The seals were fabricated with the addition of various amounts (10–90 wt.%) of 3 mol.% yttria partially stabilized zirconia to a BaO-Al2O3-CaO-SiO2 glass matrix. The sample gaskets in the form of thin frames were shaped by tape casting. The quality of the junctions between the composites and Crofer 22APU steel commonly used as an SOC interconnect was evaluated after thermal treatment of heating to 710 °C, then cooling to the working temperature of around 620 °C and then leaving them for 10h in an air atmosphere, before cooling to room temperature. The samples were also studied after 3, 5, and 10 thermal cycles to determine the changes in microstructure and to evaluate the porosity and possible crystallization of the glass phase. The compression of the seals was calculated on the basis of differences in thickness before and after thermal treatment. The influence of zirconia additions on the mechanical properties of the seals was studied. The experimental results confirmed that glass–ceramic composites are promising materials for gaskets in SOC stacks. The most beneficial properties were obtained for a composite containing 40 wt.% of YSZ.
Laser Powder Bed Fusion of Molybdenum and Mo-0.1SiC Studied by Positron Annihilation Lifetime Spectroscopy and Electron Backscatter Diffraction Methods
Authors: Ellsworth Nathan E. , Machacek Joshua R. , Kemnitz Ryan A. , Eckley Cayla C. , Sexton Brianna M. , Gearhart Joel A. , Burggraf Larry W.
Published: February 2023

Positron annihilation lifetime spectroscopy (PALS) has been used for the first time to investigate the microstructure of additively manufactured molybdenum. Despite the wide applicability of positron annihilation spectroscopy techniques to the defect analysis of metals, they have only been used sparingly to monitor the microstructural evolution of additively manufactured metals. Molybdenum and molybdenum with a dilute addition (0.1 wt%) of nano-sized silicon carbide, prepared via laser powder bed fusion (LPBF) at four different scan speeds: 100, 200, 400, and 800 mm/s, were studied by PALS and compared with electron backscatter diffraction analysis. The aim of this study was to clarify the extent to which PALS can be used to identify microstructural changes resulting from varying LPBF process parameters. Grain sizes and misorientation results do not correlate with positron lifetimes indicating the positrons are sampling regions within the grains. Positron annihilation spectroscopy identified the presence of dislocations and nano-voids not revealed through electron microscopy techniques and correlated with the findings of SiO2 nanoparticles in the samples prepared with silicon carbide. The comparison of results indicates the usefulness of positron techniques to characterize nano-structure in additively manufactured metals due to the significant increase in atomic-level information.
Hydrothermal Synthesis of ZnO Superstructures with Controlled Morphology via Temperature and pH Optimization
Authors: Ejsmont Aleksander , Goscianska Joanna
Published: February 2023

Zinc oxide, as a widely used material in optics, electronics, and medicine, requires a complete overview of different conditions for facile and easily reproducible syntheses. Two types of optimization of ZnO hydrothermal preparation from zinc acetate and sodium hydroxide solution are presented, which allowed for obtaining miscellaneous morphologies of materials. The first was a temperature-controlled synthesis from 100 to 200 °C, using citric acid as a capping agent. The formation of hexagonal rods at the lowest temperature was evidenced, which agglomerated to flower-like structures at 110 and 120 °C. It was followed by transformation to flake-like roses at 160 °C, up to disordered structures composed of nanosized plates (>180 °C). The transformations were generated through a temperature change, which had an impact on the diffusion effect of hydroxide and citrate complexes. The second optimization was the hydrothermal synthesis free of organic additives and it included only a pH variation from 7.5 to 13.5. It was found that by utilizing a slow-dropping process and varying amounts of NaOH solutions, it is possible to obtain well-formed hexagonal pellets at pH 8.0–8.5. Strongly basic conditions of pH 11.0 and 13.5 impeded superstructure formations, giving small elongated particles of ZnO. All samples were characterized by high phase purity and crystallinity, with a specific surface area of 18–37 m2/g, whereas particle size distribution indicated a predominance of small particles (<1 μm).
Effects of Laser Cutting Parameters on the Magnetic Properties of 50W350 High-Grade Non-Oriented Electrical Steel
Authors: Xiang Qian , Cheng Lin , Wu Kaiming
Published: February 2023

Based on the application demand of laser cutting technology in non-oriented electrical steel, the influencing mechanisms of laser cutting parameters on the magnetic properties of 50W350 high-grade non-oriented electrical steel were investigated in this work. The specific total loss was utilized to evaluate the quality of cutting methods and the cutting parameter combinations. The results showed that the deterioration of the specific total loss was mainly due to the increase in hysteresis loss. Compared to traditional mechanic shearing, laser cutting generally degrades the magnetic properties under the evaluation index ΔP1.0/50. However, in some cases, laser cutting is superior to the mechanic shearing method under the evaluation index ΔP1.5/50. The main parameters related to laser cutting exhibited complicated influencing mechanisms on the specific total loss of 50W350 high-grade non-oriented electrical steel. However, based on the results of the experiments designed using the Box–Behnken model, the laser cutting parameters were optimized and the evaluation indexes have been significantly improved.
Study on the Single Sheet Measurement Method for AC Magnetic Measurement on Grain-Oriented Electrical Steel
Authors: Xiang Qian , Cheng Lin , Wu Kaiming
Published: February 2023

To quickly and accurately measure the AC magnetic properties of grain-oriented electrical steel by means of the existing measuring system designed for the magnetizing current method (MC), specifically the SST (92) single sheet method, in this work, the H-coil (HC) measuring system, which directly senses the magnetic field strength of the tested sample, was designed to measure the AC magnetic properties of the grain-oriented electrical steel. The assumed effective magnetic path length introduced in the MC method was corrected by comparing the measurement results obtained by means of HC and MC methods. The results found that specific total loss measured by the HC method was significantly lower than that measured by the classical magnetizing current (MC) method. Taking the HC method as the reference, the influencing factors of the effective magnetic path length was studied. It was found that the actual effective magnetic path length depends on the investigated sample characteristics, the measurement conditions, as well as yoke characteristics. The actual effective magnetic path length introduced in the MC method is examined to be more than 450 mm, fluctuating around 468 mm.
Method of Fuzzy Analysis of Qualitative-Environmental Threat in Improving Products and Processes (Fuzzy QE-FMEA)
Authors: Pacana Andrzej , Siwiec Dominika
Published: February 2023

Improving products and production processes is necessary to ensure the competitiveness of the organisation. As part of these improvements, the popular approach is to use the FMEA method (Failure Mode and Effect Analysis). In the traditional FMEA approach, only the qualitative aspect is included, i.e., the analysis of the quality level of products or processes, its possible incompatibilities, and then proposing improving actions for them. It seems insufficient in times of expansion of the idea of sustainable development and dynamically changing customer requirements. Hence, the purpose of the research is to develop a fuzzy QE-FMEA method to simultaneously analyze hazards for product quality and the natural environment. This method will be based on a fuzzy decision environment. The main elements of originality of the developed method are: (i) extension of the characteristics of the selection of ratings for indicators with triangular fuzzy numbers and the development of a new characteristics of the selection of ratings for the environmental impact indicator, (ii) development of a selection matrix for the qualitative-environmental indicator (QE) according to the rules of triangular fuzzy numbers, (iii) determination of the method of estimating the value of the threat priority, additionally considering the qualitative-environmental indicator (RQE). The complement of research is developed procedure of the Fuzzy QE-FMEA method. It was shown that it is possible to include the effects of incompatibilities (effects of defects occurring in products or processes), which were simultaneously assessed considering the importance and impact on the natural environment. This method will be useful for any company for analysing defects of any products or processes mainly with significant impact on the natural environment.
Finite Element Modeling and Vibration Control of Plates with Active Constrained Layer Damping Treatment
Authors: Huang Zhicheng , Peng Huanyou , Wang Xingguo , Chu Fulei
Published: February 2023

An enhanced lightness and thinness is the inevitable trend of modern industrial production, which will also lead to prominent low-frequency vibration problems in the associated structure. To solve the vibration problem of thin plate structures in various engineering fields, the active constrained layer damping (ACLD) thin plate structure is taken as the research object to study vibration control. Based on the FEM method, energy method, and Hamilton principle, the dynamic model of an ACLD thin plate structure is derived, in which the Golla–Hughes–McTavish (GHM) model is used to characterize the damping characteristics of the viscoelastic layer, and the equivalent Rayleigh damping is used to characterize the damping characteristics of the base layer. The order of the model is reduced based on the high-precision physical condensation method and balance reduction method, and the model has good controllability and observability. An LQR controller is designed to actively control the ACLD sheet, and the controller parameters and piezoelectric sheet parameters are optimized. The results show that the finite element model established in this paper is accurate under different boundary conditions, and the model can still accurately and reliably describe the dynamic characteristics of the original system in the time and frequency domain after using the joint reduction method. Under different excitation and boundary conditions, LQR control can effectively suppress structural vibration. Considering the performance and cost balance, the most suitable control parameter for the system is: Q-matrix coefficient is between 1 × 104 and 1 × 105, the R-matrix coefficient is between 1 and 10, and the thickness of the piezoelectric plate is 0.5 mm.
The Study of Localized Crack-Induced Effects of Nonlinear Vibro-Acoustic Modulation
Authors: Broda Dariusz , Mendrok Krzysztof , Silberschmidt Vadim V. , Pieczonka Lukasz , Staszewski Wieslaw J.
Published: February 2023

The nonlinear interaction of longitudinal vibration and ultrasound in beams with cracks is investigated. The central focus is on the localization effect of this interaction, i.e., the locally enhanced nonlinear vibro-acoustic modulation. Both numerical and experimental investigations are undertaken. The finite element (FE) method is used to investigate different crack models, including the bi-linear crack, open crack, and breathing crack. A parametric study is performed considering different crack depths, locations, and boundary conditions in a two-dimensional beam model. The study shows that observed nonlinearities (i.e., nonlinear crack–wave modulations) are particularly strong in the vicinity of the crack, allowing not only for crack localization but also for the separation of the crack-induced nonlinearity from other sources of nonlinearity.
Multi-Energy and Fast-Convergence Iterative Reconstruction Algorithm for Organic Material Identification Using X-ray Computed Tomography
Authors: Iovea Mihai , Stanciulescu Andrei , Hermann Edward , Neagu Marian , Duliu Octavian G.
Published: February 2023

In order to significantly reduce the computing time while, at the same time, keeping the accuracy and precision when determining the local values of the density and effective atomic number necessary for identifying various organic material, including explosives and narcotics, a specialized multi-stage procedure based on a multi-energy computed tomography investigation within the 20–160 keV domain was elaborated. It consisted of a compensation for beam hardening and other non-linear effects that affect the energy dependency of the linear attenuation coefficient (LAC) in the chosen energy domain, followed by a 3D fast reconstruction algorithm capable of reconstructing the local LAC values for 64 energy values from 19.8 to 158.4 keV, and, finally, the creation of a set of algorithms permitting the simultaneous determination of the density and effective atomic number of the investigated materials. This enabled determining both the density and effective atomic number of complex objects in approximately 24 s, with an accuracy and precision of less than 3%, which is a significantly better performance with respect to the reported literature values.
Evaluation of an Imine-Linked Polymer Organic Framework for Storage and Release of H2S and NO
Authors: Carvalho Sílvia , Pires João , Moiteiro Cristina , Pinto Moisés L.
Published: February 2023

Hydrogen sulfide (H2S) and nitric oxide (NO) are especially known as toxic and polluting gases, yet they are also endogenously produced and play key roles in numerous biological processes. These two opposing aspects of the gases highlight the need for new types of materials to be developed in addition to the most common materials such as activated carbons and zeolites. Herein, a new imine-linked polymer organic framework was obtained using the inexpensive and easy-to-access reagents isophthalaldehyde and 2,4,6-triaminopyrimidine in good yield (64%) through the simple and catalyst-free Schiff-base reaction. The polymeric material has microporosity, an ABET surface area of 51 m2/g, and temperature stability up to 300 °C. The obtained 2,4,6-triaminopyrimidine imine-linked polymer organic material has a higher capacity to adsorb NO (1.6 mmol/g) than H2S (0.97 mmol/g). Release studies in aqueous solution showed that H2S has a faster release (3 h) from the material than NO, for which a steady release was observed for at least 5 h. This result is the first evaluation of the possibility of an imine-linked polymer organic framework being used in the therapeutic release of NO or H2S.
A New Method for Inversion of Dam Foundation Hydraulic Conductivity Using an Improved Genetic Algorithm Coupled with an Unsaturated Equivalent Continuum Model and Its Application
Authors: Peng Jiayi , Shen Zhenzhong , Xu Liqun , Gan Lei , Tan Jiacheng
Published: February 2023

Seepage is a main cause of dam failure, and its stability analysis is the focus of a dam’s design, construction, and management. Because a geological survey can only determine the range of a dam foundation’s hydraulic conductivity, hydraulic conductivity inversion is crucial in engineering. However, current inversion methods of dam hydraulic conductivity are either not accurate enough or too complex to be directly used in engineering. Therefore, this paper proposes a new method for the inversion of hydraulic conductivity with high application value in hydraulic engineering using an improved genetic algorithm coupled with an unsaturated equivalent continuum model (IGA–UECM). This method is implemented by a new code that fully considers engineering applicability. In addition to overcoming the premature convergence shortcomings of traditional genetic algorithms, it converges faster than Bayesian optimization and tree-structured Parzen estimator inversion algorithms. This method is verified by comparing the water head from drilling exploration and inversion. The results of the inversion are used to study the influence of a cement grouting curtain layout scheme on the seepage field of the Hami concrete-face rockfill dam in China, which is used as an engineering application case of the IGA–UECM. The law of the seepage field is reasonable, which verifies the validity of the IGA–UECM. The new inversion method of hydraulic conductivity and the proposed cement grouting curtain layout in this study offer possible strategies for the design, construction, and management of concrete-face rockfill dams.
Developing Improved Corrosion-Resistant AA5083—BN/WC Composites for Tribological Applications
Authors: Ammar Hany R. , Sherif Elsayed M. , Sivasankaran Subbarayan , Almufadi Fahad A. , Mekky Abdel-baset H.
Published: February 2023

In this study, corrosion-resistant AA5083—BN/WC composites were developed for tribological applications through adequate control of the reinforcement content (WC and BN) in the matrix (AA5083 alloy). The effects of 6% and 12% tungsten carbide (WC) as well as 6% and 12% boron nitride (BN) additions on the corrosion behavior of AA5083 aluminum composite in 3.5% NaCl solution were carried out. Electrochemical techniques such as cyclic potentiodynamic polarization (CPP), changes in the chronoamperometric current with time (CCT), and electrochemical impedance spectroscopy (EIS) were utilized. The polarization results showed that the addition of 6% WC to the AA5083 alloy matrix improved its resistance to corrosion (RP). Rp exhibited an additional increase by adding 12% WC to the matrix. The values of RP were observed to increase for the AA5083 composite when adding 6% BN, and the highest RP values were recorded for the composite that contains 12% BN. The results obtained by the CPP method were confirmed by CCT and EIS measurements, where the presence of WC and BN protected the developed AA5083- BN/WC composites against corrosion. The corrosion resistance revealed an additional improvement with an increase in WC and BN content from 6% to 12%. The results also confirm that pitting corrosion decreased in the presence of WC and BN in the fabricated composites.
3D DEM Simulations and Experiments on Spherical Impactor Penetrating into the Elongated Particles
Authors: Li Ping , Li Yanjie , Hua Xia , Guo Yu , Curtis Jennifer Sinclair
Published: February 2023

In this study, a brass or glass spherical impactor vertically penetrating into a granular bed composed of mono-sized spherical or elongated particles was simulated with three-dimensional (3D) discrete element method (DEM). Good agreement of the particle masses in the cup before and after penetration can be found in the simulations and experiments. The effects of particle length (Lp), friction coefficient, and particle configuration on the penetration depth of the impactor, ejecta mass, and solid volume fraction describing the response of the granular bed are discussed. The penetration depth is negatively correlated with Lp as the corresponding solid volume fraction of the granular bed decreases. A smaller friction coefficient leads to a larger penetration depth of the impactor and more ejection of particles. When the impactor is penetrating the Lp = 10 mm elongated particles, the penetration depth is negatively correlated to the order parameter and solid volume fraction.
The λ-Point Map between Two Legendre Plane Curves
Authors: Alghanemi Azeb , AlGhawazi Abeer
Published: February 2023

The λ-point map between two Legendre plane curves, which is a map from the plane into the plane, is introduced. The singularity of this map is studied through this paper and many known plane map singularities are realized as special cases of this construction. Precisely, the corank one and corank two singularities of the λ-point map between two Legendre plane curves are investigated and the geometric conditions for this map to have corank one singularities, such as fold, cusp, swallowtail, lips, and beaks are obtained. Additionally, the geometric conditions for the λ-point map to have a sharksfin singularity, which is a corank two singularity, are obtained.
Influence of the Internal Structure on the Integral Risk of a Complex System on the Example of the Risk Minimization Problem in a “Star” Type Structure
Authors: Shiroky Alexander , Kalashnikov Andrey
Published: February 2023

This paper is devoted to studying the influence of the structure of a complex system on its integral risk. When solving risk management problems, it often becomes necessary to take into account structural effects, which most often include risk transfer and failure propagation. This study discusses the influence of the position of the elements of a protected system inside a fixed structure of the “star” type on its integral risk. The authors demonstrate that the problem of the optimal placement of elements in such a structure from the point of view of minimizing the risk cannot be precisely solved by analytical methods and propose an algorithm for solving it with bounded errors. For the case of equal expected damages in case of a successful attack of a system element, the authors calculate upper estimates for the relative error of solving the placement problem using the proposed algorithm and also propose a methodology for rapid risk assessment for systems with a “star” type structure. Finally, for the particular case when the risks of elements are in a certain ratio, the authors have found an exact solution to the problem of the optimal placement of elements.
On the Approximation by Bivariate Szász–Jakimovski–Leviatan-Type Operators of Unbounded Sequences of Positive Numbers
Authors: Alotaibi Abdullah
Published: February 2023

In this paper, we construct the bivariate Szász–Jakimovski–Leviatan-type operators in Dunkl form using the unbounded sequences αn, βm and ξm of positive numbers. Then, we obtain the rate of convergence in terms of the weighted modulus of continuity of two variables and weighted approximation theorems for our operators. Moreover, we provide the degree of convergence with the help of bivariate Lipschitz-maximal functions and obtain the direct theorem.