bluuebunny/crossref_metadata_2025 huggingface dataset:
Vagus Nerve Stimulation and Its Cardioprotective Abilities: A Systematic Review
Authors: Elamin Ahmed Banibella Abdelmagied , Forsat Kowthar , Senok Solomon Silas , Goswami Nandu
Published: February 2023

Despite the vagus nerve stimulator (VNS) being used in neuroscience, it has recently been highlighted that it has cardioprotective functions. However, many studies related to VNS are not mechanistic in nature. This systematic review aims to focus on the role of VNS in cardioprotective therapy, selective vagus nerve stimulators (sVNS), and their functional capabilities. A systemic review of the current literature was conducted on VNS, sVNS, and their ability to induce positive effects on arrhythmias, cardiac arrest, myocardial ischemia/reperfusion injury, and heart failure. Both experimental and clinical studies were reviewed and assessed separately. Of 522 research articles retrieved from literature archives, 35 met the inclusion criteria and were included in the review. Literature analysis proves that combining fiber-type selectivity with spatially-targeted vagus nerve stimulation is feasible. The role of VNS as a tool for modulating heart dynamics, inflammatory response, and structural cellular components was prominently seen across the literature. The application of transcutaneous VNS, as opposed to implanted electrodes, provides the best clinical outcome with minimal side effects. VNS presents a method for future cardiovascular treatment that can modulate human cardiac physiology. However, continued research is needed for further insight.
Clinical Results of a Modified Doty’s Technique for Supravalvular Aortic Stenosis
Authors: Lv Lizhi , Lang Xinyue , Zhang Simeng , Wang Cheng , Jin Yuanhao , Wang Qiang
Published: February 2023

This study aimed to assess the early and mid-term results of the modified Doty’s technique compared with the traditional Doty’s technique in patients with congenital supravalvular aortic stenosis (SVAS). We retrospectively included 73 consecutive SVAS patients in Beijing and Yunnan Fuwai Hospitals between 2014 and 2021. Patients were divided into the modified technique (n = 9) and the traditional technique group (n = 64). The modified technique involves altering the right head of the symmetrical inverted pantaloon-shaped patch into an asymmetrical triangular form to prevent compression of the right coronary artery ostium. The primary safety outcome was in-hospital surgery-related complications and the primary effectiveness outcome was re-operation at follow-up. The Mann–Whitney U test and Fisher’s exact test were used to test the group difference. The median age at operation was 50 months (IQR 27.0–96.0). Twenty-two (30.1%) of the patients were female. The median follow-up was 23.5 months (IQR 3.0–46.0). No in-hospital surgery-related complications and follow-up re-operation occurred in the modified technique group, but the traditional technique group had 14 (21.8%) surgery-related complications and 5 (7.9%) re-operation. Patients with the modified technique had a well-developed aortic root and no aortic regurgitation occurred. A modified technique could be considered for patients with poor aortic root development to reduce postoperative surgery-related complications.
Impact of Evolution of Self-Expandable Aortic Valve Design: Peri-Operative and Short-Term Outcomes
Authors: Bei Evangelia , Voudris Vasileios , Kalogeras Konstantinos , Oikonomou Evangelos , Iakovou Ioannis , Kosmas Ilias , Kalantzis Charalampos , Vavuranakis Michael-Andrew , Pantelidis Panteleimon , Lazaros George , Tousoulis Dimitrios , Tsioufis Constantinos , Vavuranakis Manolis
Published: February 2023

A few data exist on the differences of implantable aortic valve bio-prostheses. We investigate three generations of self-expandable aortic valves in terms of the outcomes. Patients undergoing transcatheter aortic valve implantation (TAVI) were allocated into three groups according to the valve type: group A (CoreValveTM), group B (EvolutTMR) and group C (EvolutTMPRO). The implantation depth, device success, electrocardiographic parameters, need for permanent pacemaker (PPM), and paravalvular leak (PVL) were assessed. In the study, 129 patients were included. The final implantation depth did not differ among the groups (p = 0.07). CoreValveTM presented greater upward jump of the valve at release (2.88 ± 2.33 mm vs. 1.48 ± 1.09 mm and 1.71 ± 1.35 mm, for groups A, B, and C, respectively, p = 0.011). The device success (at least 98% for all groups, p = 1.00) and PVL rates (67% vs. 58%, vs. 60% for groups A, B, and C, respectively, p = 0.64) did not differ. PPM implantation within 24 h (33% vs. 19% vs. 7% for groups A, B, and C, respectively, p = 0.006) and until discharge (group A: 38% vs. group B: 19% and group C: 9%, p = 0.005) was lower in the newer generation valves. Newer generation valves present better device positioning, more predictable deployment, and fewer rates of PPM implantation. No significant difference in PVL was observed.
Inhibition of γδ-TcR or IL17a Reduces T-Cell and Neutrophil Infiltration after Ischemia/Reperfusion Injury in Mouse Liver
Authors: Al Mogrampi Saant , Boumpoureka Christina , Afaloniati Hara , Lagou Maria , Angelopoulou Katerina , Anestakis Doxakis , Tampouratzi Zoi Gerasimina , Iliadis Stavros , Antoniadis Nikolaos , Giakoustidis Alexandros , Papalois Apostolos , Papadopoulos Vasileios , Poutahidis Theofilos , Giakoustidis Dimitrios
Published: February 2023

Neutrophil and T-cell recruitment contribute to hepatic ischemia/reperfusion injury. The initial inflammatory response is orchestrated by Kupffer cells and liver sinusoid endothelial cells. However, other cell types, including γδ-Τ cells, seem to be key mediators in further inflammatory cell recruitment and proinflammatory cytokine release, including IL17a. In this study, we used an in vivo model of partial hepatic ischemia/reperfusion injury (IRI) to investigate the role of the γδ-Τ-cell receptor (γδTcR) and the role of IL17a in the pathogenesis of liver injury. Forty C57BL6 mice were subjected to 60 min of ischemia followed by 6 h of reperfusion (RN 6339/2/2016). Pretreatment with either anti-γδΤcR antibodies or anti-IL17a antibodies resulted in a reduction in histological and biochemical markers of liver injury as well as neutrophil and T-cell infiltration, inflammatory cytokine production and the downregulation of c-Jun and NF-κΒ. Overall, neutralizing either γδTcR or IL17a seems to have a protective role in liver IRI.
Use of NEedle Versus suRFACE Recording Electrodes for Detection of Intraoperative Motor Warnings: A Non-Inferiority Trial. The NERFACE Study Part II
Authors: Dulfer Sebastiaan E. , Gadella Maria C. , Tamási Katalin , Absalom Anthony R. , Lange Fiete , Scholtens-Henzen Carola H. M. , Faber Christopher , Wapstra Frits H. , Groen Rob J. M. , Sahinovic Marko M. , Ulkatan Sedat , Drost Gea
Published: February 2023

In the NERFACE study part I, the characteristics of muscle transcranial electrical stimulation motor evoked potentials (mTc-MEPs) recorded from the tibialis anterior (TA) muscles with surface and subcutaneous needle electrodes were compared. The aim of this study (NERFACE part II) was to investigate whether the use of surface electrodes was non-inferior to the use of subcutaneous needle electrodes in detecting mTc-MEP warnings during spinal cord monitoring. mTc-MEPs were simultaneously recorded from TA muscles with surface and subcutaneous needle electrodes. Monitoring outcomes (no warning, reversible warning, irreversible warning, complete loss of mTc-MEP amplitude) and neurological outcomes (no, transient, or permanent new motor deficits) were collected. The non-inferiority margin was 5%. In total, 210 (86.8%) out of 242 consecutive patients were included. There was a perfect agreement between both recording electrode types for the detection of mTc-MEP warnings. For both electrode types, the proportion of patients with a warning was 0.12 (25/210) (difference, 0.0% (one-sided 95% CI, 0.014)), indicating non-inferiority of the surface electrode. Moreover, reversible warnings for both electrode types were never followed by permanent new motor deficits, whereas among the 10 patients with irreversible warnings or complete loss of amplitude, more than half developed transient or permanent new motor deficits. In conclusion, the use of surface electrodes was non-inferior to the use of subcutaneous needle electrodes for the detection of mTc-MEP warnings recorded over the TA muscles.
Green Biodegradable Polylactide-Based Polyurethane Triblock Copolymers Reinforced with Cellulose Nanowhiskers
Authors: Khattab Mohamed , Abdel Hady Noha , Dahman Yaser
Published: February 2023

A novel series of biodegradable polylactide-based triblock polyurethane (TBPU) copolymers covering a wide range of molecular weights and compositions were synthesized for potential use in biomedical applications. This new class of copolymers showed tailored mechanical properties, improved degradation rates, and enhanced cell attachment potential compared to polylactide homopolymer. Triblock copolymers, (TB) PL-PEG-PL, of different compositions were first synthesized from lactide and polyethylene glycol (PEG) via ring-opening polymerization in the presence of tin octoate as the catalyst. After which, polycaprolactone diol (PCL-diol) reacted with TB copolymers using 1,4-butane diisocyanate (BDI) as a nontoxic chain extender to form the final TBPUs. The final composition, molecular weight, thermal properties, hydrophilicity, and biodegradation rates of the obtained TB copolymers, and the corresponding TBPUs were characterized using 1H-NMR, GPC, FTIR, DSC, and SEM, and contact angle measurements. Results obtained from the lower molecular weight series of TBPUs demonstrated potential use in drug delivery and imaging contrast agents due to their high hydrophilicity and degradation rates. On the other hand, the higher molecular weight series of TBPUs exhibited improved hydrophilicity and degradation rates compared to PL-homopolymer. Moreover, they displayed improved tailored mechanical properties suitable for utilization as bone cement, or in regeneration medicinal applications of cartilage, trabecular, and cancellous bone implants. Furthermore, the polymer nanocomposites obtained by reinforcing the TBPU3 matrix with 7% (w/w) bacterial cellulose nanowhiskers (BCNW) displayed a ~16% increase in tensile strength, and 330% in % elongation compared with PL-homo polymer.
Influence of ECAP Parameters on the Structural, Electrochemical and Mechanical Behavior of ZK30: A Combination of Experimental and Machine Learning Approaches
Authors: Shaban Mahmoud , Alateyah Abdulrahman I. , Alsharekh Mohammed F. , Alawad Majed O. , BaQais Amal , Kamel Mokhtar , Alsunaydih Fahad Nasser , El-Garaihy Waleed H. , Salem Hanadi G.
Published: February 2023

Several physics-based models have been utilized in material design for the simulation and prediction of material properties. In this study, several machine-learning (ML) approaches were used to construct a prediction model to analyze the influence of equal-channel angular pressing (ECAP) parameters on the microstructural, corrosion and mechanical behavior of the biodegradable magnesium alloy ZK30. The ML approaches employed were linear regression, the Gaussian process, and support vector regression. For the optimization of the alloy’s performance, experiments were conducted on ZK30 billets using different ECAP routes, channel angles, and number of passes. The adopted ML model is an adequate predictive model which agreed with the experimental results. ECAP die angles had an insignificant effect on grain refinement, compared to the route type. ECAP via four passes of route Bc (rotating the sample 90° on its longitudinal axis after each pass in the same direction) was the most effective condition producing homogenous ultrafine grain distribution of 1.92 µm. Processing via 4-Bc and 90° die angle produced the highest hardness (97-HV) coupled with the highest tensile strength (344 MPa). The optimum corrosion rate of 0.140 mils penetration per year (mpy) and the optimum corrosion resistance of 1101 Ω·cm2 resulted from processing through 1-pass using the 120°-die. Grain refinement resulted in reducing the corrosion rates and increased corrosion resistance, which agreed with the ML findings.
A Data-Driven Model for Ice-Breaking Resistance of Structure Based on Non-Smooth Discrete Element Method and Artificial Neural Network Method
Authors: Sun Zhe , Qiu Yongjin , Yang Biye , Jia Zichen , Zhang Guiyong , Zong Zhi
Published: February 2023

In this paper, a data-driven model based on the Non-smooth Discrete Element Method (NDEM) and Artificial Neural Network Method (ANN) is proposed for the computation of the ice-breaking resistance of the structure. The idea of so-called “meta-modelling”, which means establishing an Artificial Neural Network (ANN) model based on a pre-computed ice failure database to avoid the time-consuming direct resolving of the ice fracture process, was integrated in the non-smooth discrete element method (NDEM). The developed model was validated by simulating the ice-breaking process of the cone structure, and the computational results match well with the experimental ones in the literature. After that, the effects of various parameters on the ice-breaking resistance were analyzed by the developed model. It was found that the factors that have great influence on the resistance of cone structure in level ice condition are the cone angle, navigation velocity and ice thickness.
Risk Assessment of the Wild Edible Leccinum Mushrooms Consumption According to the Total Mercury Content
Authors: Šnirc Marek , Jančo Ivona , Hauptvogl Martin , Jakabová Silvia , Demková Lenka , Árvay Július
Published: February 2023

Wild-growing edible mushrooms contain many biologically valuable substances. However, they are considered a risk commodity due to their extremely high capacity for bioaccumulation of potential risk elements and pollutants from the environment. Four bolete mushrooms from the genus Leccinum were collected from 16 forested areas of Slovakia from June to October 2019. The total mercury content in soil and fruiting body parts was determined by an AMA-254 Advanced Mercury Analyzer. Soil pollution by total mercury was evaluated by contamination factor (Cfi). Bioaccumulation factor (BCF), translocation factor (Qc/s), percentage of provisional tolerable weekly intake (%PTWI), and target hazard quotient (THQ) were used to describe and compare uptake and transition abilities of mushrooms, and the health risk arising from consumption of the mushrooms. Total mercury content varied between 0.05 to 0.61 mg kg−1 DW in the soil/substrate samples, and between 0.16 and 5.82 (caps), and 0.20 and 3.50 mg kg−1 DW (stems) in fruiting body samples. None of the analyzed locations represented a health risk based on %PTWI values, however, three locations may pose a significant health risk from the perspective of THQ values.
Effect of Hydrogen on AM Pyroptosis Induced by Severe Burns in Rats
Authors: Luo Ning , Lin Hua , Zhang Linlin , Jiang Yi , Zhao Yue , Han Qingqing , Wang Xin , Yu Yonghao , Qin Chao
Published: February 2023

Background: Hydrogen has anti-inflammatory and antioxidant effects and is beneficial to multiple organs. However, its effect on alveolar macrophage (AM) pyroptosis induced by burns is still unclear. The purpose of this research was to study the possible positive effects of hydrogen on burn-induced lung injury and the effects of hydrogen on AM pyroptosis during acute lung injury (ALI) induced by burns. Methods: In this study, histological changes in rat lungs in vivo were evaluated by micro-CT, and histological changes in isolated lungs were evaluated by hematoxylin and eosin (HE) staining. The expressions of leucine rich repeat (LRR) and pyrin domain (PYD) containing protein 3 (NLRP3), caspase-1 and Gasdermin-D (GSDMD) were analyzed by Western blotting. The expression of GSDMD was measured by immunofluorescence to evaluate the levels of lung inflammation and pyroptosis. The level of inflammation was assessed by enzyme-linked immunosorbent assay (ELISA). Pyroptosis was observed by transmission electron microscopy. Results: We observed that severe burn resulted in increased IL-1β and IL-18, overexpression of NLRP3 and caspase-1 proteins, and pyroptosis in rat lung tissues, as demonstrated by GSDMD overexpression and electron microscopy of AMs. We also observed that hydrogen treatment partially reversed the increase in lung tissue density and reduced pulmonary inflammation. Moreover, hydrogen reduced the HE pathological injury score in the lung tissues of severely burned rats. Hydrogen treatment significantly reduced the contents of IL-1β and IL-18 in the lung tissues and decreased the expression of NLRP3, caspase-1 and GSDMD proteins compared with the burn group. Transmission electron microscopy results also showed that the number of AM membrane pores was significantly reduced in the hydrogen treatment group. Conclusions: The results of this study suggest that hydrogen may protect against ALI induced by burn injury by inhibiting pyroptosis of macrophages via NLRP3.
Venture Capitalists on Boards and Corporate Innovation
Authors: Jing Li , Zhang Huiying
Published: February 2023

Venture capital has a significant positive impact on corporate innovation. However, innovation has great risks. Investors often lack sufficient confidence in innovation, which often leads to investors stopping their investment or to inadequate support for innovation behavior. Therefore, enhancing investor confidence is crucial. Monitoring is considered to be the most direct and common way to promote investor confidence. This paper mainly focus on the effect of venture capitalist monitoring on corporate innovation. We use companies listed in the Shenzhen and Shanghai stock exchanges from 2009 to 2017 as samples. We performed a metrological test and a series of robustness tests and found that venture capitalists on boards play a significant role in promoting corporate innovation. When dividing the sample according to the experience of venture capital or the governance level of the corporation, we found that venture capitalists on boards with high experience or in corporations with high-quality governance have a greater impact on corporate innovation. Furthermore, we studied the monitoring mechanism of venture capital on boards and found that the monitoring of venture capital can alleviate managers’ anxiety about being dismissed due to innovation failure.
The Coupling Relationship between Green Finance and Ecosystem Service Demand in China Based on an Improved Coupling Coordination Degree Model
Authors: Wang Haojia , Zhao Dandan , Zhou Qiaowei , Ke Qinhua , Dong Guanglong
Published: February 2023

With the rapid development of society and economy, people’s demand for ecosystem services is constantly increasing. All countries support this demand by vigorously developing green finance. The coordinated development of green finance and ecosystem service demand is of great significance for sustainable development. Most of the existing studies separately study green finance or ecosystem service demand, separating the relationship between the two. At present, there is still a lack of clear understanding of the coupling relationship between green finance and ecosystem service demand. In addition, in the existing coupling relationship calculation models, the setting of relevant parameters is subjective. Therefore, based on the green finance and ecosystem service demand database of 30 provinces in China from 2010 to 2017, this paper firstly evaluates the green finance and ecosystem service demand quantitatively, and then analyzes the coupling coordination relationship between them by using an improved coupling coordination degree model. The results show that: (1) compared with the traditional coupling coordination degree model, the contribution coefficient of each subsystem in the improved coupling coordination degree model has a more sufficient basis, and more objective evaluation results; (2) from 2010 to 2017, the level of green finance in China’s provinces increased significantly, showing a spatial pattern of “high in the east and low in the west”; the ecosystem services demand increased first and then decreased, with an increase in nearly two-thirds of provinces; (3) the coupling coordination relationship between green finance and ecosystem service demand in China’s provinces was optimized continuously from 2010 to 2017, showing the spatial differentiation of “eastern China > central China > northeast China > western China”; (4) in 2017, the coupling coordination degree of green finance and ecosystem service demand in Guangdong Province was the highest, reaching a high level of coordination, while Qinghai Province was the lowest, as a result of a serious level of incoordination. It is worth noting that the comprehensive development level of green finance in China is still low and seriously lags behind the development level of ecosystem services demand. In the future, green and low-carbon transformation should be accelerated to promote the sustainable development of financial ecology.
Sexually Transmitted Infections Prevalence and Cascade of Care among Undocumented Sex Workers: A Twenty-Year-Long Experience
Authors: Donisi Alessandra , Colpani Agnese , Zauli Beatrice , De Vito Andrea , Fiore Vito , Babudieri Sergio , Madeddu Giordano
Published: February 2023

Undocumented migrant sex-workers (SW) are vulnerable to Sexually Transmitted Infections (STIs). However, data regarding prevalence and linkage-to-care are lacking. Defining epidemiology is crucial to implement preventive measures. We report data from SW attending a facility for migrants in Piacenza, Italy. We collected medical records from 1999 until 2021. Quantitative variables were summarized as mean and standard deviation (SD), and qualitative ones by absolute and relative frequencies. Logistic regression analysis was performed to assess the relationship between sociodemographic, clinical variables, positive testing, and loss to follow-up (LFU). Overall, 1035 STI episodes were collected, 917 in cisgender-females (CF), and 118 in transgender-females (TF). Overall, 474 diagnoses were made. Three-hundred-ninety-two/474 (82.7%) started therapy, and 264/474 (55.7%) complied with a follow-up. Only 51.5% of HBV and 30.8% of HIV were linked to care. Having symptoms (OR 1.70 (95% CI 1.06–2.73), p = 0.028) and previous STIs (OR 1.36 (95% CI 1.04–1.77), p = 0.022) were associated with a higher chance of STIs, while at-risk intercourse to lower risk (OR 0.19 (95% CI 0.07–0.49), p = 0.001). TF had higher odds of bloodborne infections and syphilis (OR 2.61 (95% CI 1.17–5.80), p = 0.019). Regarding follow-up, the older the patient, the higher the LFU (OR 1.05 (95% CI 1.01–1.10), p = 0.021). Our data showed a high prevalence of STIs and LFU among undocumented SW. TF are even more vulnerable. Further efforts should be put into targeted interventions.
Alteration in Levels of Specific miRNAs and Their Potential Protein Targets between Human Pancreatic Cancer Samples, Adjacent Normal Tissue, and Xenografts Derived from These Tumors
Authors: O’Neill Fiona , Allen-Coyle Taylor-Jade , Roche Sandra , Meiller Justine , Conlon Neil T. , Swan Niall , Straubinger Robert M. , Geoghegan Justin , Straubinger Ninfa L. , Conlon Kevin , McDermott Ray , O’Sullivan Finbarr , Henry Michael , Meleady Paula , McVey Gerard , O’Connor Robert , Moriarty Michael , Clynes Martin
Published: February 2023

Herein, we describe the global comparison of miRNAs in human pancreatic cancer tumors, adjacent normal tissue, and matched patient-derived xenograft models using microarray screening. RNA was extracted from seven tumor, five adjacent normal, and eight FI PDX tumor samples and analyzed by Affymetrix GeneChip miRNA 4.0 array. A transcriptome analysis console (TAC) was used to generate comparative lists of up- and downregulated miRNAs for the comparisons, tumor vs. normal and F1 PDX vs. tumor. Particular attention was paid to miRNAs that were changed in the same direction in both comparisons. We identified the involvement in pancreatic tumor tissue of several miRNAs, including miR4534, miR3154, and miR4742, not previously highlighted as being involved in this type of cancer. Investigation in the parallel mRNA and protein lists from the same samples allowed the elimination of proteins where altered expression correlated with corresponding mRNA levels and was thus less likely to be miRNA regulated. Using the remaining differential expression protein lists for proteins predicted to be targeted for differentially expressed miRNA on our list, we were able to tentatively ascribe specific protein changes to individual miRNA. Particularly interesting target proteins for miRs 615-3p, 2467-3p, 4742-5p, 509-5p, and 605-3p were identified. Prominent among the protein targets are enzymes involved in aldehyde metabolism and membrane transport and trafficking. These results may help to uncover vulnerabilities that could enable novel approaches to treating pancreatic cancer.
Pre-Operative Functional Mapping in Patients with Brain Tumors by fMRI and MEG: Advantages and Disadvantages in the Use of One Technique over the Other
Authors: Cargnelutti Elisa , Tomasino Barbara
Published: February 2023

Pre-operative mapping of brain functions is crucial to plan neurosurgery and investigate potential plasticity processes. Due to its availability, functional magnetic resonance imaging (fMRI) is widely used for this purpose; on the other hand, the demanding cost and maintenance limit the use of magnetoencephalography (MEG), despite several studies reporting its accuracy in localizing brain functions of interest in patient populations. In this review paper, we discuss the strengths and weaknesses of both techniques, from a methodological perspective first; then, we scrutinized and commented on the findings from 16 studies, identified by a database search, that made pre-operative assessments using both techniques in patients with brain tumors. We commented on the results by accounting for study limitations associated with small sample sizes and variability in the used tasks. Overall, we found that, although some studies reported the superiority for MEG, the majority of them underlined the complementary use of these techniques and suggested assessment using both. Indeed, both fMRI and MEG present some disadvantages, although the development of novel devices and processing procedures has enabled ever more accurate assessments. In particular, the development of new, more feasible MEG devices will allow widespread availability of this technique and its routinely combined use with fMRI.
Theoretical Investigations on Tribological Properties of Air Foil Thrust Bearings during Start-Up Process
Authors: Wu Fangling , Hu Yang
Published: February 2023

During the start-up process, air foil thrust bearings (AFTBs) come into contact and are prone to localized overheating and even failure. Frequent starts and stops are the major sources of wear. In this study, a transient mixed lubrication model considering the air rarefaction effect is established. In the model, asperity contact between the top foil of the air foil thrust bearing (AFTB) and the rotor surface is considered using a deterministic approach, and the deformation of the foil structure is considered using the elastic-aerodynamic coupling. The influences of bearing compliance, external load, acceleration time and contact stiffness on the tribological properties during the start-up process are investigated. The results show that the lift-off speed increases with the increase of the bearing compliance and of the external load. Specifically, the lift-off speed of AFTBs increases from 1950 rpm to 5325 rpm when the bearing compliance increases linearly from 0.2 to 1.0. When the external load increases from 10 N to 80 N, the lift-off speed is increased by approximately 30 times, from 450 rpm to 13,575 rpm. Furthermore, a decrease in the acceleration time of the rotor generates a decrease in the lift-off time and an increase in the contact stiffness of the bearing leads to a decrease in the lift-off speed of the bearing. By exploring the effects of the bearing parameters and working conditions on the tribological performance of AFTBs during start-up, the results presented in this study can provide theoretical support for improving start-up performance and designing high-reliability and long-life AFTBs.
Tribological Properties of CNTs-Reinforced Nano Composite Materials
Authors: Ujah Chika Oliver , Kallon Daramy Vandi Von , Aigbodion Victor Sunday
Published: February 2023

High modulus of about 1 TPa, high thermal conductivity of over 3000 W/mK, very low coefficient of thermal expansion (CTE), high electrical conductivity, self-lubricating characteristics and low density have made CNTs one of the best reinforcing materials of nano composites for advanced structural, industrial, high strength and wear-prone applications. This is so because it has the capacity of improving the mechanical, tribological, electrical, thermal and physical properties of nanocomposites. So, this study is aimed at providing the latest discoveries on the tribological behavior of CNTs-reinforced composites. The composites reviewed included metal matrix composites (MMCs), polymer matrix composites (PMCs) and ceramic matrix composites (CMCs) reinforced with CNTs. Their tribological characteristics, uses, production challenges, conclusion and recommendations are presented. The work presented the best technique to disperse CNTs on matrices to avoid its agglomeration, since agglomeration is one of the major challenges in reinforcing with CNTs. It was discovered that ball milling destroys the outer walls of CNTs but recommended that ultrasonication and functionalization before ball milling eliminate this adverse effect of ball milling. In addition, it was discovered that addition of CNTs to composite matrices improved the wear resistance, reduced the wear volume, decreased the coefficient of friction (COF) and provided self-lubricating effect on MMCs, PMCs and CMCs.
Sintering, Microstructure, and Mechanical Properties of TiTaNbZrHf High-Entropy Alloys Prepared by Cold Isostatic Pressing and Pressure-Less Sintering of Hydrides
Authors: Chen Yubing , Liu Peidong , Dong Zhaowang , Liu Hanning , Wang Junjie , Guo Xueyi , Xia Yang , Wang Qinmeng
Published: February 2023

A TiTaNbZrHf refractory high-entropy alloy (RHEA) was synthesized through a cold isostatic pressing and a pressure-less sintering process in a hydrogen atmosphere using a powder mixture of metal hydride prepared either by mechanical alloying (MA) or by rotating mixing. This study investigates how differences in powder particle sizes impact the RHEA’s microstructure and mechanical properties. HCP (a = b = 3.198 Å, c = 5.061 Å) and BCC2 (a = b = c = 3.40 Å) phases were observed in the microstructure of coarse powder TiTaNbZrHf RHEAs at 1400 °C. In contrast, fine powder RHEAs were found to possess two-phase structures of HCP and BCC1 (a = b = c = 3.36 Å) with a higher hardness of 431 HV, compression strength of 1620 MPa, and a plasticity of >20%.
Ionic Liquids as Working Fluids for Heat Storage Applications: Decomposition Behavior of N-Butyl-N-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate
Authors: Nardelli Francesca , Berretti Enrico , Lavacchi Alessandro , Pitzalis Emanuela , Freni Angelo , Pizzanelli Silvia
Published: February 2023

Ionic liquids (ILs) represent promising working fluids to be used in thermal energy storage (TES) technologies thanks to their peculiar properties, such as low volatility, high chemical stability, and high heat capacity. Here, we studied the thermal stability of the IL N-butyl-N-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([BmPyrr]FAP), a potential working fluid for TES applications. The IL was heated at 200 °C for up to 168 h either in the absence or in contact with steel, copper, and brass plates to simulate the conditions used in TES plants. High-resolution magic angle spinning nuclear magnetic resonance spectroscopy was found to be useful for the identification of the degradation products of both the cation and the anion, thanks to the acquisition of 1H, 13C, 31P, and 19F-based experiments. In addition, elemental analysis was performed on the thermally degraded samples by inductively coupled plasma optical emission spectroscopy and energy dispersive X-ray spectroscopy. Our analysis shows a significant degradation of the FAP anion upon heating for more than 4 h, even in the absence of the metal/alloy plates; on the other hand, the [BmPyrr] cation displays a remarkable stability also when heated in contact with steel and brass.
A Novel Catalytic Ceramic Conversion Treatment of Zr702 to Combat Wear
Authors: Xiong Xinhe , Li Xiaoying , Alexander James , Zhang Zhenxue , Dong Hanshan
Published: February 2023

Zr and its alloys are widely used in multiple areas, including the nuclear and medical fields. Previous studies indicate that a ceramic conversion treatment (C2T) of Zr-based alloys can address the issues of low hardness, high friction, and poor wear resistance of Zr based alloys. This paper introduced a novel catalytic ceramic conversion treatment (C3T) to Zr702 by pre-depositing a catalytic film (such as silver, gold, platinum, etc.) before the ceramic conversion treatment, which efficiently promoted the C2T process, in terms of reduced treatment times, with a thick, good quality, surface ceramic layer. The formed ceramic layer significantly improved the surface hardness and tribological properties of Zr702 alloy. Compared with conventional C2T, the C3T technique provided two orders of magnitude reduction of wear factor and reduced the coefficient of friction from 0.65 to <0.25. Among the C3T samples, the C3TAg and the C3TAu samples have the highest wear resistance and lowest CoF, mainly due to the self-lubricant formation during the wear processes.
Effect of Bioactive Filler Addition on the Mechanical and Biological Properties of Resin-Modified Glass Ionomer
Authors: Diniz Ana Carolina , Bauer José , Veloso Suzanni do Amaral Rodrigues , Abreu-Pereira César Augusto , Carvalho Ceci Nunes , Leitão Tarcísio Jorge , Firoozmand Leily Macedo , Maia-Filho Etevaldo Matos
Published: February 2023

The maintenance of affected dentin can promote the greater conservation of tooth structure. The development of materials that have properties capable of reducing the demineralizing potential and/or even helping in dental remineralization is important for conservative dentistry. This study aimed to evaluate, in vitro, the alkalizing potential, fluoride as well as calcium ion release ability, antimicrobial activity, and dentin remineralization properties of resin-modified glass ionomer cement (RMGIC) incorporated with a bioactive filler (niobium phosphate (NbG) and bioglass (45S5)). The study samples were grouped into RMGIC, NbG, and 45S5. The materials’ alkalizing potential, ability to release calcium as well as fluoride ions, and antimicrobial properties concerning Streptococcus mutans UA159 biofilms were analyzed. The remineralization potential was evaluated using the Knoop microhardness test, which was performed at different depths. The alkalizing and fluoride release potential was higher for the 45S5 group (p < 0.001) over time. An increase in the microhardness of demineralized dentin was observed in the 45S5 and NbG groups (p < 0.001). No differences in biofilm formation were observed between the bioactive materials, although 45S5 exhibited lower biofilm acidogenicity at different time points (p < 0.001) and greater calcium ion release in the microbial environment. A resin-modified glass ionomer cement enriched with bioactive glasses, particularly 45S5, is a promising alternative for the treatment of demineralized dentin.
Electropolishing Stainless Steel Optimization Using Surface Quality, Dimensional Accuracy, and Electrical Consumption Criteria
Authors: Beamud-González Elena María , Núñez-López Pedro José , García-Plaza Eustaquio
Published: February 2023

Electropolishing (EP) processes require high electrical consumption that must be optimized to minimize production costs without sacrificing the objectives of surface quality and dimensional accuracy. The aim of the present paper was to analyze the effects of the interelectrode gap, initial surface roughness, electrolyte temperature, current density, and EP time on aspects of the EP process applied to AISI 316L stainless steel, which have not been examined in the literature, such as polishing rate, final surface roughness, dimensional accuracy, and electrical consumption cost. In addition, the paper aimed to obtain optimum individual and multi-objective considering criteria of surface quality, dimensional accuracy, and electrical consumption cost. The results showed that the electrode gap was not significant on the surface finish or current density, and the EP time was the parameter having the greatest effect on all criteria analyzed, with a temperature of 35 °C showing the best electrolyte performance. The initial surface texture with the lowest roughness Ra10 (0.5 ≤ Ra ≤ 0.8 μm) obtained the best results with a maximum polishing rate of ~90% and minimum final roughness (Ra) of ~0.035 μm. The response surface methodology showed the EP parameter effects and the optimum individual objective. The desirability function obtained the best global multi-objective optimum, while the overlapping contour plot provided optimum individual and simultaneous per polishing range.
The Effects of Hemisphere Dome Orientation on the Structure of Diamond-like Carbon Film Prepared Using Ion Beam Assisted Deposition
Authors: Shang Peng , Ma Yuanfei , Zhang Zhenyun , Sun Peng , Liu Huasong , Shi Hongchun , Lin Quan , Xue Tao , Ji Yiqin
Published: February 2023

Diamond-like carbon (DLC) has attracted significant attention in the recent decades because of its unique properties and applications. Ion beam assisted deposition (IBAD) has been widely established in industry due to the advantages of easy handling and scalability. In this work, a hemisphere dome model is specially designed as a substrate. The influence of the surface orientation on the coating thickness, Raman ID/IG ratio, surface roughness and the stress of the DLC films are examined. The reduction in the stress in the DLC films reflects the lower energy-dependence in diamond due to the varied sp3/sp2 fraction and columnar growth pattern. The variation of the surface orientation provides an efficient means of tailoring the properties and microstructure of the DLC films.
Surface-Dependent Hydrogen Evolution Activity of Copper Foil
Authors: Kong Ling-Jie , Hu Xin-Zhuo , Chen Chuan-Qi , Kulinich Sergei A. , Du Xi-Wen
Published: February 2023

Single-crystal planes are ideal platforms for catalytic research. In this work, rolled copper foils with predominantly (220) planes were used as the starting material. By using temperature gradient annealing, which caused grain recrystallization in the foils, they were transformed to those with (200) planes. In acidic solution, the overpotential of such a foil (10 mA cm−2) was found to be 136 mV lower than that of a similar rolled copper foil. The calculation results show that hollow sites formed on the (200) plane have the highest hydrogen adsorption energy and are active centers for hydrogen evolution. Thus, this work clarifies the catalytic activity of specific sites on the copper surface and demonstrates the critical role of surface engineering in designing catalytic properties.
Progress on the Fabrication of Superconducting Wires and Tapes via Hot Isostatic Pressing
Authors: Lei Zhenyu , Yao Chao , Guo Wenwen , Wang Dongliang , Ma Yanwei
Published: February 2023

Fabrication of high-performance superconducting wires and tapes is essential for large-scale applications of superconducting materials. The powder-in-tube (PIT) method involves a series of cold processes and heat treatments and has been widely used for fabricating BSCCO, MgB2, and iron-based superconducting wires. The densification of the superconducting core is limited by traditional heat treatment under atmospheric pressure. The low density of the superconducting core and a large number of pores and cracks are the main factors limiting the current-carrying performance of PIT wires. Therefore, to improve the transport critical current density of the wires, it is essential to densify the superconducting core and eliminate pores and cracks to enhance grain connectivity. Hot isostatic pressing (HIP) sintering was employed to improve the mass density of superconducting wires and tapes. In this paper, we review the development and application of the HIP process in the manufacturing of BSCCO, MgB2, and iron-based superconducting wires and tapes. The development of HIP parameters and the performance of different wires and tapes are reviewed. Finally, we discuss the advantages and prospects of the HIP process for the fabrication of superconducting wires and tapes.
Mechanical Performance and Cytotoxicity of an Alginate/Polyacrylamide Bipolymer Network Developed for Medical Applications
Authors: Mouchati Abdullah , Yagoubi Najet
Published: February 2023

Several hydrogels could be used as scaffolds for tissue engineering and a model of extracellular matrices for biological studies. However, the scope of alginate in medical applications is often severely limited by its mechanical behavior. In the present study, the modification of the mechanical properties of the alginate scaffold is obtained by its combination with polyacrylamide in order to obtain a multifunctional biomaterial. The advantage of this double polymer network is due to an improvement in the mechanical strength with regard to the alginate alone, and in particular, its Young’s modulus values. The morphological study of this network was carried out by scanning electron microscopy (SEM). The swelling properties were also studied over several time intervals. In addition to mechanical property requirements, these polymers must meet several biosafety parameters as part of an overall risk management strategy. Our preliminary study illustrates that the mechanical property of this synthetic scaffold depends on the ratio of the two polymers (alginate, polyacrylamide) which allows us to choose the appropriate ratio to mimic replaceable body tissue and be used in various biological and medical uses, including 3D cell culture, tissue engineering, and protection against local shocks.
Evaluating the Stability of PLA-Lignin Filament Produced by Bench-Top Extruder for Sustainable 3D Printing
Authors: Zaidi Siti Aisyah Syazwani , Kwan Cham Eng , Mohan Denesh , Harun Shuhaida , Luthfi Abdullah Amru Indera , Sajab Mohd Shaiful
Published: February 2023

As additive manufacturing continues to evolve, there is ongoing discussion about ways to improve the layer-by-layer printing process and increase the mechanical strength of printed objects compared to those produced by traditional techniques such as injection molding. To achieve this, researchers are exploring ways of enhancing the interaction between the matrix and filler by introducing lignin in the 3D printing filament processing. In this work, research has been conducted on using biodegradable fillers of organosolv lignin, as a reinforcement for the filament layers in order to enhance interlayer adhesion by using a bench-top filament extruder. Briefly, it was found that organosolv lignin fillers have the potential to improve the properties of polylactic acid (PLA) filament for fused deposition modeling (FDM) 3D printing. By incorporating different formulations of lignin with PLA, it was found that using 3 to 5% lignin in the filament leads to an improvement in the Young’s modulus and interlayer adhesion in 3D printing. However, an increment of up to 10% also results in a decrease in the composite tensile strength due to the lack of bonding between the lignin and PLA and the limited mixing capability of the small extruder.
Ultrasonic Fatigue Testing of Structural Steel S275JR+AR with Insights into Corrosion, Mean Stress and Frequency Effects
Authors: Gorash Yevgen , Comlekci Tugrul , Styger Gary , Kelly James , Brownlie Frazer , Milne Lewis
Published: February 2023

There are limited experimental data on VHCF for structural steels for >107 cycles. Unalloyed low-carbon steel S275JR+AR is a common structural material for the heavy machinery in minerals, sand and aggregate applications. The purpose of this research is to investigate the fatigue behaviour in the gigacycle domain (>109 cycles) for S275JR+AR grade steel. This is achieved using accelerated ultrasonic fatigue testing in as-manufactured, pre-corroded and non-zero mean stress conditions. As internal heat generation is a massive challenge for ultrasonic fatigue testing of structural steels which exhibit a pronounced frequency effect, effective temperature control is crucial for implementation of testing. The frequency effect is assessed by comparing the test data at 20 kHz and 15–20 Hz. Its contribution is significant, as there is no overlap between the stress ranges of interest. The obtained data are intended to be applied to the fatigue assessments of the equipment operating at the frequency for up to 1010 cycles over years of continuous service.
A Review of the Mechanical Properties of Graphene Aerogel Materials: Experimental Measurements and Computer Simulations
Authors: Qi Penghao , Zhu Hanxing , Borodich Feodor , Peng Qing
Published: February 2023

Graphene aerogels (GAs) combine the unique properties of two-dimensional graphene with the structural characteristics of microscale porous materials, exhibiting ultralight, ultra-strength, and ultra-tough properties. GAs are a type of promising carbon-based metamaterials suitable for harsh environments in aerospace, military, and energy-related fields. However, there are still some challenges in the application of graphene aerogel (GA) materials, which requires an in-depth understanding of the mechanical properties of GAs and the associated enhancement mechanisms. This review first presents experimental research works related to the mechanical properties of GAs in recent years and identifies the key parameters that dominate the mechanical properties of GAs in different situations. Then, simulation works on the mechanical properties of GAs are reviewed, the deformation mechanisms are discussed, and the advantages and limitations are summarized. Finally, an outlook on the potential directions and main challenges is provided for future studies in the mechanical properties of GA materials.
Effect of Ultrasonic Shot Peening and Laser Shock Peening on the Microstructure and Microhardness of IN738LC Alloys
Authors: Liu Sijia , Kim Youngdae , Jung Jinesung , Bae Seongguk , Jeong Sungho , Shin Keesam
Published: February 2023

IN738LC is a conventional-cast Ni-based superalloy intended for power generation and aerospace applications. Typically, ultrasonic shot peening (USP) and laser shock peening (LSP) are utilized to enhance cracking, creep, and fatigue resistance. In this study, the optimal process parameters for USP and LSP were established by observing the microstructure and measuring the microhardness of the near-surface region of IN738LC alloys. The LSP impact region (modification depth) was approximately 2500 μm, which was much higher than the USP impact depth of 600 μm. The observation of the microstructural modification and resulting strengthening mechanism revealed that the build-up of dislocations upon peening with plastic deformation was crucial for alloy strengthening in both methods. In contrast, significant strengthening via γ′ shearing was observed only in the USP-treated alloys.
Some Quantum Integral Inequalities for (p, h)-Convex Functions
Authors: Kantalo Jirawat , Wannalookkhee Fongchan , Nonlaopon Kamsing , Budak Hüseyin
Published: February 2023

In this paper, we derive an identity of the q-definite integral of a continuous function f on a finite interval. We then use such identity to prove some new quantum integral inequalities for (p,h)-convex function. The results obtained in this paper generalize previous work in the literature.