bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy and Safety Ablation Index-Guided High-Energy Linear Ablation for Persistent Atrial Fibrillation: PVI Plus Linear Ablation of Mitral Isthmus and Posterior Box Isolation
Authors: Li Xi , Liu Tao , Cui Bo , Zhang Jinlin , Chen Yanhong , Wu Gang
Published: January 2023

Background: For patients with persistent atrial fibrillation (AF), whether linear ablation should be performed remains controversial, and the efficacy and safety for ablation index (AI)-guided high-energy linear ablation of mitral isthmus (MI) and left atrial (LA) posterior box isolation is still unclear. The aims of this study were to assess the feasibility and clinical success rate of pulmonary veins isolation (PVI) combined with linear ablation of LA roof and posterior inferior (posterior wall isolation) and MI compare with the PVI-alone method in patients of persistent AF. Methods and results: 362 consecutive persistent AF patients were enrolled from two electrophysiology centers. A total of 200 cases were in PVI-plus group and 162 cases were in PVI-alone group. The PVI-alone group received wide circumferential isolation of both ipsilateral pulmonary veins. PVI combined with linear ablation of left atrial posterior wall isolation (LAPWI)and MI were performed in the PVI-plus group. The primary study end point was the first recurrence of an atrial arrhythmia. After 24 months, freedom from the primary endpoint was achieved in 73.5% of the patients in the PVI-plus group and 62.5% in the PVI-alone group (hazard ratio = 0.62, 95% confidence interval: 0.43–0.91, log rank p = 0.012). The procedure-related complication rates were 2.5% in PVI-plus group and 1.9% in PVI-alone group (p = 0.808). Conclusion: In this study, the ablation strategy of ablation (PVI plus linear ablation of mitral isthmus and posterior box isolation) was feasible and safe for persistent AF patients. Compared with the PVI-alone method, it improved outcomes in patients with persistent AF.
Maximal Effort Cytoreduction in Epithelial Ovarian Cancer: Perioperative Complications and Survival Outcomes from a Retrospective Cohort
Authors: Haidopoulos Dimitrios , Pergialiotis Vasilios , Zachariou Eleftherios , Sapantzoglou Ioakim , Thomakos Nikolaos , Stamatakis Emmanouil , Alexakis Nikolaos
Published: January 2023

Background: Rates of maximal effort cytoreductive surgery in ovarian cancer patients increase gradually the last decade. The purpose of the present study is to evaluate factors that contribute to survival and morbidity outcomes in this group of patients. Methods: We retrospectively reviewed patient records of epithelial ovarian cancer patients with an intermediate and high Mayo Clinic surgical complexity score, operated between January 2010 and December 2018. Results: Overall, 107 patients were enrolled in the present study with a median age of 62 years (23–84) and a follow-up of 32 months (2–156). Thirteen Clavien-Dindo grade IIIa complications were documented in 10 patients (9.3%). Of all the investigated factors, only stage IVb (p = 0.027) and interval debulking surgery (p = 0.042) affected overall survival rates. Overall survival outcomes of patients operated on a primary setting started to differentiate compared to those that received neo-adjuvant chemotherapy after the 4th postoperative year. Conclusions: Maximal effort cytoreductive procedures should be considered feasible in the modern surgical era, as they are accompanied by acceptable rates of perioperative morbidity. Hence, every effort should be made to perform them in the primary setting, rather than following neoadjuvant chemotherapy as current evidence favor increased survival rates of patients that will likely surpass an interval of observation of more than 4 years.
Epidemiology of Inflammatory Bowel Diseases: A Population Study in a Healthcare District of North-West Italy
Authors: Caviglia Gian Paolo , Garrone Angela , Bertolino Chiara , Vanni Riccardo , Bretto Elisabetta , Poshnjari Anxhela , Tribocco Elisa , Frara Simone , Armandi Angelo , Astegiano Marco , Saracco Giorgio Maria , Bertolusso Luciano , Ribaldone Davide Giuseppe
Published: January 2023

The burden of inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is increasing worldwide. The aim of the present study was to investigate the clinical characteristics and the changing in epidemiology of IBD in the Healthcare District Bra, an area of North-West Italy accounting for 57,615 inhabitants as of 31 December 2021. Clinical and demographic data were retrieved from administrative databases and the medical records of general practitioners (n = 39) at Verduno Hospital. Prevalence and incidence rates were calculated for the time span 2016–2021 and compared to the 2001–2006 period. IBD prevalence was 321.2 per 100,000 population in 2021 and, compared with 2006 (200 per 100,000 population), the prevalence has increased at a rate of +46%. Similarly, the average incidence has increased from the period 2001–2006 (6.7 per 100,000 population/year) to the period 2016–2021 (18.0 per 100,000 population/year) at a rate of +169%; such an increase was greater for CD than UC. In the 2016–2021 period, the mean age at diagnosis was 42.0 ± 17.4 years and 30.9% required at least one hospitalization, while 10.9% of patients underwent at least one surgery. In conclusion, the prevalence and incidence of IBD distinctly increased over a two decade period in the Healthcare District Bra paralleling the results of previous surveys from other Italian regions. These data warrant specific interventions to improve patients’ management and resources’ allocation.
Factors Associated with Postpartum Maternal Functioning in Black Women: A Secondary Analysis
Authors: Floyd James Kortney , Smith Betsy E. , Robinson Millicent N. , Thomas Tobin Courtney S. , Bulles Kelby F. , Barkin Jennifer L.
Published: January 2023

In the United States, 29–44% of Black women experience postpartum depressive symptoms (PDS), yet few are properly identified and/or connected to mental care services. The purpose of this secondary analysis was to examine the relationship between maternal functioning and clinical variables (PDS, maternal–infant attachment), racial variable (Black racial identity types—low race salience, assimilated and miseducated, self-hating, anti-White, multiculturalist, and conflicted), and sociodemographic characteristics (relationship status, education, insurance, childbirth type). A total of 116 women living in the southern United States were included in the analysis. Multivariate analyses revealed that Black racial identity (p = 0.02), PDS (p < 0.0001), maternal–infant attachment (p < 0.0001), and educational level (p = 0.03) were independently associated with maternal functioning. This work provides new evidence regarding the role of various clinical and racial factors on Black postpartum women’s adjustment to motherhood. This analysis also adds to the growing body of evidence of reliability for the BIMF in Black postpartum women.
Microleakage Study of a Bulk Fill over an Uncured Adhesive System
Authors: Pinto Mariana Vaz , Pires Salomé , Marto Carlos Miguel , Amaro Inês , Coelho Ana , Sousa José , Ferreira Manuel Marques , Botelho Maria Filomena , Carrilho Eunice , Abrantes Ana Margarida , Paula Anabela Baptista
Published: January 2023

This study aimed to evaluate and compare the microleakage of composite resin restorations under a total-etch adhesive system applied with two different techniques, with and without cure. Cavities were made on the buccal surface of twenty-six intact teeth and subsequently restored with bulk-fill flow composite resin (SDR®® flow+) and conventional resin (Spectra™ ST HV). Two experimental groups were created, one where the total-etch adhesive (Prime & Bond Active®) was cured and another where the adhesive was not cured before placing the flowable resin. Two control groups were also created, negative and positive. After the restorations were finished the, teeth were submerged in a solution of sodium pertechnetate (99mTcNaO4) for 3 h to evaluate the microleakage. The results showed more infiltration of radioisotopes characterized by the highest total count values of microleakage in group 1 (cured adhesive) and in the positive control. Group 2 (noncured adhesive) and the negative control showed lower values. We therefore considered that these groups were similar since their p-value was less than 0.05, with no statistically significant difference. Group 4 showed a statistically significant increase in relation to group 3 (p = 0.027). We concluded that the method of bulk-fill composite resins with noncured adhesive agents can have a positive effect on the longevity of bond strengths, with reduced microleakage.
Multi-Response Optimization of Ti6Al4V Support Structures for Laser Powder Bed Fusion Systems
Authors: Dimopoulos Antonios , Zournatzis Ilias , Gan Tat-Hean , Chatzakos Panagiotis
Published: January 2023

Laser Powder Bed Fusion (LPBF) is one of the most commonly used and rapidly developing metal Additive Manufacturing (AM) technologies for producing optimized geometries, complex features, and lightweight components, in contrast to traditional manufacturing, which limits those characteristics. However, this technology faces difficulties with regard to the construction of overhang structures and warping deformation caused by thermal stresses. Producing overhangs without support structures results in collapsed parts, while adding unnecessary supports increases the material required and post-processing. The purpose of this study was to evaluate the various support and process parameters for metal LPBF, and propose optimized support structures to minimize Support Volume, Support Removal Effort, and Warping Deformation. The optimization approach was based on the Design of Experiments (DOE) methodology and multi-response optimization, by 3D printing and studying overhang geometries from 0° to 45°. For this purpose, EOS Titanium Ti64 Grade 5 powder was used, a Ti6Al4V alloy commonly employed in LPBF. For 0° overhangs, the optimum solution was characterized by an average Tooth Height, large Tooth Top Length, low X, Y Hatching, and high Laser Speed, while for 22.5° and 45° overhangs, it was characterized by large Tooth Height, low Tooth Top Length, high X, Y Hatching, and high Laser Speed.
Development of Electromagnetic Current Meter for Marine Environment
Authors: Chen Shizhe , Wu Yushang , Liu Shixuan , Yang Yingdong , Wan Xiaozheng , Yang Xianglong , Zhang Keke , Wang Bo , Yan Xingkui
Published: January 2023

Ocean current is one of the most important parameters in ocean observation, and ocean current measurement based on electromagnetic induction is becoming more and more important because of its advantages such as simple structure and high measurement accuracy. However, it is difficult to detect weak current signals in a complex marine environment. In this paper, an electromagnetic induction current measurement scheme based on lock-in amplification technology is proposed. Key technologies such as the evaluation of induced current intensity, overall design, circuit design, and orientation design of the current meter were studied. The prototype of the electromagnetic current meter was developed and tested in the laboratory and at sea. The repeatability of current velocity and current direction was higher than 1.5 cm/s and 1.5°, respectively. A comparison test between the electromagnetic current meter prototype and Nortek ADCP (Acoustic Doppler Current Profiler) installed on a buoy at sea was carried out, and the correlation coefficients of the current velocity and current direction datum were 0.90 and 0.96, respectively. Through continuous on-site and fault-free operations at sea, the experimental data show that the electromagnetic current meter has good adaptability at sea, which provides feasible technical and equipment support for ocean current observation.
Optimization of a Regional Marine Environment Mobile Observation Network Based on Deep Reinforcement Learning
Authors: Zhao Yuxin , Liu Yanlong , Deng Xiong
Published: January 2023

The observation path planning of an ocean mobile observation network is an important part of the ocean mobile observation system. With the aim of developing a traditional algorithm to solve the observation path of the mobile observation network, a complex objective function needs to be constructed, and an improved deep reinforcement learning algorithm is proposed. The improved deep reinforcement learning algorithm does not need to establish the objective function. The agent samples the marine environment information by exploring and receiving feedback from the environment. Focusing on the real-time dynamic variability of the marine environment, our experiment shows that adding bidirectional recurrency to the Deep Q-network allows the Q-network to better estimate the underlying system state. Compared with the results of existing algorithms, the improved deep reinforcement learning algorithm can effectively improve the sampling efficiency of the observation platform. To improve the prediction accuracy of the marine environment numerical prediction system, we conduct sampling path experiments on a single platform, double platform, and five platforms. The experimental results show that increasing the number of observation platforms can effectively improve the prediction accuracy of the numerical prediction system, but when the number of observation platforms exceeds 2, increasing the number of observation platforms will not improve the prediction accuracy, and there is a certain degree of decline. In addition, in the multi-platform experiment, the improved deep reinforcement learning algorithm is compared with the unimproved algorithm, and the results show that the proposed algorithm is better than the existing algorithm.
CRISPR/Cas9-Mediated Multiplexed Genome Editing in Aspergillus oryzae
Authors: Li Qinghua , Lu Jinchang , Zhang Guoqiang , Zhou Jingwen , Li Jianghua , Du Guocheng , Chen Jian
Published: January 2023

Aspergillus oryzae has great potential and competitive advantages to be developed as an excellent expression system, owing to its powerful protein secretion ability, complex post-translational modification, and safety characteristics. However, the low efficiency of genetic modification and gene function analysis is an urgent problem to be solved in A. oryzae and other filamentous fungal systems. Therefore, establishing efficient genetic transformation and multiplexed genome editing tools is significant for developing A. oryzae expression systems, and revealing its intrinsic mechanisms. In this study, the high-efficiency transformation of A. oryzae was achieved by optimizing the preparation conditions of protoplasts, and the random editing efficiency of the CRISPR/Cas9 system in A. oryzae for single and double genes reached 37.6% and 19.8%, respectively. With the aid of the selection marker, such as color or resistance, the editing efficiency of single and double genes can reach 100%. Based on the developed CRISPR/Cas9 genome editing method, the heterologous lipase gene (TLL) achieves precise integration at different genetic loci in one step. The efficient and accurate acquisition of positive transformants indicated that the morphological gene yA could be used as a helpful selection marker for genome editing in A. oryzae. In conclusion, the developed system improves the efficiency of transformation and multiplexed genome editing for A. oryzae. It provides a practical method for developing the A. oryzae high-efficiency expression system for heterologous proteins.
Unraveling the Secrets of a Double-Life Fungus by Genomics: Ophiocordyceps australis CCMB661 Displays Molecular Machinery for Both Parasitic and Endophytic Lifestyles
Authors: de Menezes Thaís Almeida , Aburjaile Flávia Figueira , Quintanilha-Peixoto Gabriel , Tomé Luiz Marcelo Ribeiro , Fonseca Paula Luize Camargos , Mendes-Pereira Thairine , Araújo Daniel Silva , Melo Tarcisio Silva , Kato Rodrigo Bentes , Delabie Jacques Hubert Charles , Ribeiro Sérvio Pontes , Brenig Bertram , Azevedo Vasco , Drechsler-Santos Elisandro Ricardo , Andrade Bruno Silva , Góes-Neto Aristóteles
Published: January 2023

Ophiocordyceps australis (Ascomycota, Hypocreales, Ophiocordycipitaceae) is a classic entomopathogenic fungus that parasitizes ants (Hymenoptera, Ponerinae, Ponerini). Nonetheless, according to our results, this fungal species also exhibits a complete set of genes coding for plant cell wall degrading Carbohydrate-Active enZymes (CAZymes), enabling a full endophytic stage and, consequently, its dual ability to both parasitize insects and live inside plant tissue. The main objective of our study was the sequencing and full characterization of the genome of the fungal strain of O. australis (CCMB661) and its predicted secretome. The assembled genome had a total length of 30.31 Mb, N50 of 92.624 bp, GC content of 46.36%, and 8,043 protein-coding genes, 175 of which encoded CAZymes. In addition, the primary genes encoding proteins and critical enzymes during the infection process and those responsible for the host–pathogen interaction have been identified, including proteases (Pr1, Pr4), aminopeptidases, chitinases (Cht2), adhesins, lectins, lipases, and behavioral manipulators, such as enterotoxins, Protein Tyrosine Phosphatases (PTPs), and Glycoside Hydrolases (GHs). Our findings indicate that the presence of genes coding for Mad2 and GHs in O. australis may facilitate the infection process in plants, suggesting interkingdom colonization. Furthermore, our study elucidated the pathogenicity mechanisms for this Ophiocordyceps species, which still is scarcely studied.
Understanding Employees’ Energy Saving in the Workplace: DR and the Philippines’ Realities
Authors: Camacho Luis J. , Pasco Michael , Banks Moises , Pasco Randall , Almanzar Marisela , Rodriguez Alvin , Amoo Akinlawon , Rosima Nelda
Published: January 2023

Understanding how employees act at work to save energy and the meaning for sustainability and environmental protection is essential. This research aimed to analyze the influences of Subjective Norms (SN), Descriptive Norms (DN), and Environmental Knowledge (EK) on employees’ intention to save energy (ISE) in the Philippines (PH) and the Dominican Republic (DR). The effects of SN, DN, and EK on ISE were evaluated by comparing two developing countries and the mediation effect of EK on the relationship between DN, SN, and ISE. Confirmatory factor analysis (CFA), followed by structural equation modeling and path analysis based on samples collected from employees from DR (340) and PH (339), was performed. Also, construct convergent and discriminant validity were assessed using composite reliability, maximal reliability, average variance extracted, and maximum shared variance. The findings of this study indicate that SN influences ISE positively among employees in PH (β = 0.15, p < 0.05) but not among employees in DR. Descriptive Norms positively influence ISE among employees in PH (β = 0.47, p < 0.01) and DR (β = 0.27, p < 0.01), while EK has a positive and significant influence on the ISE among employees in PH (β = 0.22, p < 0.01) and not in DR. There is a partial mediation effect between SN and EK on ISE when EK is the mediator in PH, and no mediation effects for RD. The intention to save energy is significant in economic terms because reducing energy consumption can help decrease energy costs and improve business profitability and competitiveness; in social terms, it can reduce energy consumption worldwide and improve social health, reducing gas emissions and pollution.
COVID-19 Pandemic & Financial Market Volatility; Evidence from GARCH Models
Authors: Khan Maaz , Kayani Umar Nawaz , Khan Mrestyal , Mughal Khurrum Shahzad , Haseeb Mohammad
Published: January 2023

Across the globe, COVID-19 has disrupted the financial markets, making them more volatile. Thus, this paper examines the market volatility and asymmetric behavior of Bitcoin, EUR, S&P 500 index, Gold, Crude Oil, and Sugar during the COVID-19 pandemic. We applied the GARCH (1, 1), GJR-GARCH (1, 1), and EGARCH (1, 1) econometric models on the daily time series returns data ranging from 27 November 2018 to 15 June 2021. The empirical findings show a high level of volatility persistence in all the financial markets during the COVID-19 pandemic. Moreover, the Crude Oil and S&P 500 index shows significant positive asymmetric behavior during the pandemic. Apart from this, the results also reveal that EGARCH is the most appropriate model to capture the volatilities of the financial markets before the COVID-19 pandemic, whereas during the COVID-19 period and for the whole period, each GARCH family evenly models the volatile behavior of the six financial markets. This study provides financial investors and policymakers with useful insight into adopting effective strategies for constructing portfolios during crises in the future.
The Societal Value of the Modern Zoo: A Commentary on How Zoos Can Positively Impact on Human Populations Locally and Globally
Authors: Greenwell Phillip J. , Riley Lisa M. , Lemos de Figueiredo Ricardo , Brereton James E. , Mooney Andrew , Rose Paul E.
Published: January 2023

Modern zoos and aquariums have evolved greatly since the end of the Second World War, to become centres of conservation excellence and scientific institutions for the study of animal behaviour, ecology, husbandry management. Whilst the impact of zoos and aquariums to biodiversity conservation, population management and advancement of species care is well documented, their positive impacts on society (including the communities that they are located within) is less well known. The four established aims of the modern zoo—Conservation, Education, Recreation (Engagement) and Research—provide a strong foundation for wider review and critique of the societal value of zoos and aquariums. This article synthesises what such value may be, and how it could be measured, from a systematic review of the literature pertaining to each of these four established aims. It also recommends areas of future scientific inquiry to further study the wider impact of zoos on their local communities and on human populations and behaviour more generally. Including Wellbeing as a fifth aim of the modern zoo would also cement their wider societal value. Further scrutiny of the societal value of the modern zoo enhances the value of the zoo’s living collection and the green spaces that it manages to provide accessibility to biodiversity and nature-centric education essential to long-term, planetary friendly human behaviour change.
Impact of Intellectualization of a Zoo through a FCEM-AHP and IPA Approach
Authors: Lin Yuxuan , Shimoda Ryosuke
Published: January 2023

As urbanization is growing faster, the term “Smart” is becoming more widely used. However, it is difficult to define how to objectively evaluate intellectualization. This study aims to explore an objective method of evaluating intellectualization in Japanese zoos and suggest project directions for their future development. First, we will define the unique Japanese zoo smart projects. Then, an analytic hierarchy process (AHP) will be used to determine the weights of each item, and the fuzzy comprehensive evaluation method (FCEM) will be used to evaluate the degree of construction. Finally, the strengths and weaknesses of each project will be analyzed by importance–performance analysis (IPA). The findings showed that the research subject, Ueno Zoo, is still in the early stage of smartening, and most of the items are not sufficient for users to have a full tourist experience. There is a need to increase the level of intellectualization and ease-of-use for the construction of the zoos of Tokyo. This study provides an objective approach for evaluating the intellectualization of zoos in Japan and provides a method of construction advice for intellectualization construction.
Alaska Native Allotments at Risk: Technological Strategies for Monitoring Erosion and Informing Solutions in Southwest Alaska
Authors: Lim Jonathan S. , Gleason Sean , Strehlau Hannah , Church Lynn , Nicolai Carl , Church Willard , Jones Warren
Published: January 2023

After the United States’ purchase of Alaska from Russia in 1867, Alaska Native lands have existed in a legal state of aboriginal title, whereby the land rights of its traditional occupants could be extinguished by Congress at any time. With the passage of the Alaska Native Claims Settlement Act (ANCSA) in 1971, however, Alaska Native individuals were given the opportunity to select and secure a title to ancestral lands as federally administered ANCSA 14(c) allotments. Today, though, these allotments are threatened by climate-change-driven erosion. In response, our article provides an erosion monitoring tool to quantify the damage caused by coastal and riverine erosion. Using the Yup’ik (pl. Yupiit) community of Quinhagak as a case study, we employ high-precision measurement devices and archival spatial datasets to demonstrate the immense scale of the loss of cultural lands in this region. From 1976 to 2022, an average of 30.87 m of coastline were lost according to 9 ANCSA 14(c) case studies within Quinhagak’s Traditional Land Use Area. In response, we present a free erosion monitoring tool and urge tribal entities in Alaska to replicate our methods for recording and quantifying erosion on their shareholders’ ANCSA 14(c) properties. Doing so will foster urgent dialogue between Alaskan Native communities and lawmakers to determine what measures are needed to protect Alaska Native land rights in the face of new environmental challenges.
Synthesis of Bis(1,2,3-triazolyl)alkanes in Superbasic and Solvent-Free Conditions
Authors: Marchenko Roman D. , Potapov Andrei S.
Published: January 2023

Nucleophilic substitution reactions between 1,2,3-triazole and dibromomethane or 1,2-dirbomoethane in a superbasic medium potassium hydroxide–dimethyl sulfoxide gave mixtures of the isomeric bis(1,2,3-triazolyl)alkanes, in which (1,2,3-triazol-1-yl)(1,2,3-triazol-2-yl)alkanes and bis(1,2,3-triazol-2-yl)alkanes were the dominating products, while bis(triazol-1-yl)alkanes were detected only in trace amounts. The same products could also be obtained under solvent-free conditions in a neat reaction mixture. The proposed methods are economically feasible, do not require using toxic solvents or catalysts, and make the (1,2,3-triazol-2-yl)-derivatives, inaccessible by alkyne-azide cycloaddition (click) reactions, readily available.
Design and Optimization of Thermal Field for PVT Method 8-Inch SiC Crystal Growth
Authors: Zhang Shengtao , Fu Guoqing , Cai Hongda , Yang Junzhi , Fan Guofeng , Chen Yanyu , Li Tie , Zhao Lili
Published: January 2023

As a wide bandgap semiconductor material, silicon carbide has promising prospects for application. However, its commercial production size is currently 6 inches, and the difficulty in preparing larger single crystals increases exponentially with size increasing. Large-size single crystal growth is faced with the enormous problem of radial growth conditions deteriorating. Based on simulation tools, the physical field of 8-inch crystal growth is modeled and studied. By introducing the design of the seed cavity, the radial temperature difference in the seed crystal surface is reduced by 88% from 93 K of a basic scheme to 11 K, and the thermal field conditions with uniform radial temperature and moderate temperature gradient are obtained. Meanwhile, the effects of different processing conditions and relative positions of key structures on the surface temperature and axial temperature gradients of the seed crystals are analyzed in terms of new thermal field design, including induction power, frequency, diameter and height of coils, the distance between raw materials and the seed crystal. Meanwhiles, better process conditions and relative positions under experimental conditions are obtained. Based on the optimized conditions, the thermal field verification under seedless conditions is carried out, discovering that the single crystal deposition rate is 90% of that of polycrystalline deposition under the experimental conditions. Meanwhile, an 8-inch polycrystalline with 9.6 mm uniform deposition was successfully obtained after 120 h crystal growth, whose convexity is reduced from 13 mm to 6.4 mm compared with the original scheme. The results indicate that the optimized conditions can be used for single-crystal growth.
Reflecting the Quality Degradation of Engine Oil by the Thermal Diffusivity: Radiative and Nonradiative Analyses
Authors: Gokul Vijayakumar , Swapna Mohanachandran Nair Sindhu , Korte Dorota , Sankararaman Sankaranarayana Iyer
Published: January 2023

Ageing of engine oil is an important issue determining the engine life and performance. The present work attempts to delineate the ageing-induced changes in engine oil through the mode-mismatched dual-beam thermal lens (MMDBTL) technique and other conventional spectroscopic techniques. For the analyses, engine oil samples were collected after every 200 km of runtime. As the thermal diffusivity is related to the nonradiative deexcitation upon optical absorption, comprehensive radiative and nonradiative analyses were carried out. The Ultraviolet-Visible, Fourier transform infrared, and Nuclear magnetic resonance spectroscopic analyses point to the structural modification as a result of the breaking of the long-chain hydrocarbons into ketones, aldehydes, esters, and other compounds. This modifies the absorption pattern, which can also be understood from the nonlinear refractive index study using the Z-scan technique. The compositional variations associated with the degradation upon ageing, the length of the hydrocarbon chain, and the formation of newer molecules account for the enhancement of the thermal diffusivity revealed through the MMBDTL techniques. The complementary nature of the radiative and nonradiative emission is understood from the fluorescence study. Thus, the study reveals the possibility of thermal diffusivity measurement as an effective tool for the quality monitoring of engine oil.
Cellulose-Acetate-Based Films Modified with Ag2O and ZnS as Nanocomposites for Highly Controlling Biological Behavior for Wound Healing Applications
Authors: Alharthi Amjad F. , Gouda Mohamed , Khalaf Mai M. , Elmushyakhi Abraham , Abou Taleb Manal F. , Abd El-Lateef Hany M.
Published: January 2023

For wound healing, functional films with certain physicochemical and biological properties are needed. Thus, the current work aimed to fabricate multifunctional materials comprising metal oxide nanoparticles loaded with an efficient polymer to be used as dressing material. A composite containing polymeric phases of cellulose acetate (CA) blended with zinc sulfide (ZnS), silver oxide (Ag2O), and graphene oxide (GO) was successfully synthesized. The prepared composite crystallinity was studied using the X-ray diffraction technique (XRD). Further, the functional groups and the elemental analysis were investigated using Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX). Furthermore, the surface morphology was studied using scanning electron microscopy (SEM) to obtain the shape and size of particles. SEM showed that the particles were formed in wide distribution in the range of 18–915 nm with an average size of 235 nm for Ag2O/ZnS/GO/CA. The particle size of Ag2O in the CA film was in the range between 19 and 648 nm with an average size of 216 nm, while the particle size of ZnS in CA was in the range of 12–991 nm with an average age particle size of 158 mm. In addition, EDX, based on SEM investigation, detected high carbon and oxygen quantities at around 94.21% of the composite. The contact angle decreased and reached 26.28° ± 2.12° in Ag2O/ZnS/CA. Furthermore, thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the composition was thermally stable until 300 °C. Moreover, the cell viability of “normal lung cells” reached 102.66% in vitro at a concentration of 1250 µg/mL. The antibacterial activity of Ag2O/ZnS/GO/CA was also detected against E. coli with a zone of inhibition reaching 17.7 ± 0.5 mm. Therefore, the composite can be used in biomedical applications due to its biocompatibility and antibacterial activity.
Review on Mechanoresponsive Smart Windows: Structures and Driving Modes
Authors: Chen Bo , Feng Qi , Liu Weiwei , Liu Yang , Yang Lili , Ge Dengteng
Published: January 2023

The growing awareness about the global energy crisis and extreme weather from global warming drives the development of smart windows market. Compared to conventional electrochromic, photochromic, or thermochromic smart windows, mechanoresponsive smart windows present advantages of simple construction, low cost, and excellent stability. In this review, we summarize recent developments in mechanoresponsive smart windows with a focus on the structures and properties. We outline the categories and discuss the advantages and disadvantages. Especially, we also summarize six unconventional driving modes to generate mechanical strain, including pneumatic, optical, thermal, electric, magnetic, and humidity modes. Lastly, we provide practical recommendations in prospects for future development. This review aims to provide a useful reference for the design of novel mechanoresponsive smart windows and accelerate their practical applications.
Formation of Thick Immersion Coatings and Residual Stress Evaluation in the System ZrB2–ZrO2: Experimental and Numerical Investigation
Authors: Buyakov Ales , Smolin Igor , Zimina Valentina , Fedyanin Nikita , Shmakov Vasiliy , Buyakova Svetlana
Published: January 2023

The combination of various oxide ceramics in layered and functionally graded composites allows for the development of novel materials, including for high-temperature applications. This study demonstrates the possibility of obtaining a thick ZrO2-based coating on a ZrB2–SiC ceramic substrate by the immersion method. For better wettability, the porous ZrB2–SiC substrate is treated with cold plasma without changing the structure and phase composition of the surface. Immersion of the substrate in a ZrO2-based slurry results in the formation of a gradient transition layer due to ZrO2 particle penetration into the pore volume. The interfacial residual microstresses are evaluated experimentally. The residual macrostresses in the samples are calculated by finite element simulation. It is shown that the thermal residual stresses in the ZrB2–SiC substrate are compressive and do not exceed 43 MPa. In the ZrO2 coating and transition layers of the composite, the residual stresses are tensile. Their values increase as they get closer to the outer layer of the ZrO2 coating and reach 1525 MPa. This confirms the conclusions about the presence of tensile residual stresses made in the experimental part of the work when observing crack propagation in the surface layers during indentation.
Investigation of the Resistance to High-Speed Impact Loads of a Heterogeneous Materials Reinforced with Silicon Carbide Fibers and Powder
Authors: Malikov Alexander , Golyshev Alexander
Published: January 2023

Pioneering studies on the additive manufacturing of a cermet heterogeneous material using SiC ceramic fiber were carried out. Unique studies of the damage staging (cratering) and the transition to the destruction of the formed material during high-speed impact created with the help of an electrodynamic mass accelerator have been carried out. It has been shown that the use of ceramic fiber in a metal matrix reduces the impact crater depth by 22% compared to material with ceramic particles. For the first time, the phase composition of the resulting composite was studied using synchrotron radiation. It was shown that, as a result of laser exposure, silicon carbide SiC is dissolved in the titanium matrix with the formation of secondary compounds of the TiC and Ti5Si3C types. It has been established that the use of SiC ceramic fibers leads to their better dissolution, in contrast to the use of SiC ceramic particles, with the formation of secondary phase compounds, and to an increase in mechanical characteristics.
Specimen Geometry Effect on Experimental Tensile Mechanical Properties of Tough Hydrogels
Authors: Ji Donghwan , Im Pilseon , Shin Sunmi , Kim Jaeyun
Published: January 2023

Synthetic tough hydrogels have received attention because they could mimic the mechanical properties of natural hydrogels, such as muscle, ligament, tendon, and cartilage. Many recent studies suggest various approaches to enhance the mechanical properties of tough hydrogels. However, directly comparing each hydrogel property in different reports is challenging because various testing specimen shapes/sizes were employed, affecting the experimental mechanical property values. This study demonstrates how the specimen geometry—the lengths and width of the reduced section—of a tough double-network hydrogel causes differences in experimental tensile mechanical values. In particular, the elastic modulus was systemically compared using eleven specimens of different shapes and sizes that were tensile tested, including a rectangle, ASTM D412-C and D412-D, JIS K6251-7, and seven customized dumbbell shapes with various lengths and widths of the reduced section. Unlike the rectangular specimen, which showed an inconsistent measurement of mechanical properties due to a local load concentration near the grip, dumbbell-shaped specimens exhibited a stable fracture at the reduced section. The dumbbell-shaped specimen with a shorter gauge length resulted in a smaller elastic modulus. Moreover, a relationship between the specimen dimension and measured elastic modulus value was derived, which allowed for the prediction of the experimental elastic modulus of dumbbell-shaped tough hydrogels with different dimensions. This study conveys a message that reminds the apparent experimental dependence of specimen geometry on the stress-strain measurement and the need to standardize the measurement of of numerous tough hydrogels for a fair comparison.
Shape Memory Alloys for Civil Engineering
Authors: Fang Cheng , Qiu Canxing , Zheng Yue
Published: January 2023

Shape memory alloys (SMAs) are a unique class of metals capable of recovering large strains either spontaneously or upon heating, depending on their thermal-mechanical state [...]
Instantaneous Ablation Behavior of Laminated CFRP by High-Power Continuous-Wave Laser Irradiation in Supersonic Wind Tunnel
Authors: Ma Te , Wang Jiangtao , Song Hongwei , Wang Ruixing , Yuan Wu
Published: January 2023

Experimental and numerical investigations of the instantaneous ablation behavior of laminated carbon fiber-reinforced polymer (CFRP) exposed to an intense continuous-wave (CW) laser in a supersonic wind tunnel are reported. We establish an in situ observation measurement in the experiments to examine the instantaneous ablation behavior. The surface recession depth is calculated by using the Particle Image Velocimetry (PIV) method, taking the ply angle of laminated CFRP as a reference. A coupled thermal-fluid-ablation numerical model incorporating mechanisms of oxidation, sublimation, and thermomechanical erosion is developed to solve the ablation-through problem of multilayer materials. The results show that the laser ablation depth is related to the laser power density, airflow velocity and airflow mode. Thermomechanical erosion is the primary ablation mechanism when the surface temperature is relatively low and the cavity flow mode is a closed cavity flow. When the surface temperature reaches the sublimation of carbon and the airflow mode is transformed to open cavity flow, sublimation plays a dominant role and the ablation rate of thermomechanical erosion gradually decreases.
Atherosclerotic-Derived Endothelial Cell Response Conducted by Titanium Oxide Nanotubes
Authors: Beltrán-Partida Ernesto , Valdez-Salas Benjamín , García-López Portillo Martha , Gutierrez-Perez Claudia , Castillo-Uribe Sandra , Salvador-Carlos Jorge , Alcocer-Cañez José , Cheng Nelson
Published: January 2023

Atherosclerosis lesions are described as the formation of an occlusive wall-vessel plaque that can exacerbate infarctions, strokes, and even death. Furthermore, atherosclerosis damages the endothelium integrity, avoiding proper regeneration after stent implantation. Therefore, we investigate the beneficial effects of TiO2 nanotubes (NTs) in promoting the initial response of detrimental human atherosclerotic-derived endothelial cells (AThEC). We synthesized and characterized NTs on Ti6Al4V by anodization. We isolated AThEC and tested the adhesion long-lasting proliferation activity, and the modulation of focal adhesions conducted on the materials. Moreover, ultrastructural cell-surface contact at the nanoscale and membrane roughness were evaluated to explain the results. Our findings depicted improved filopodia and focal adhesions stimulated by the NTs. Similarly, the NTs harbored long-lasting proliferative metabolism after 5 days, explained by overcoming cell-contact interactions at the nanoscale. Furthermore, the senescent activity detected in the AThEC could be mitigated by the modified membrane roughness and cellular stretch orchestrated by the NTs. Importantly, the NTs stimulate the initial endothelial anchorage and metabolic recovery required to regenerate the endothelial monolayer. Despite the dysfunctional status of the AThEC, our study brings new evidence for the potential application of nano-configured biomaterials for innovation in stent technologies.
Femtosecond Laser-Induced Periodic Surface Structures in Titanium-Doped Diamond-like Nanocomposite Films: Effects of the Beam Polarization Rotation
Authors: Pimenov Sergei M. , Zavedeev Evgeny V. , Jaeggi Beat , Neuenschwander Beat
Published: January 2023

We study the properties of laser-induced periodic surface structures (LIPSS) formed on titanium-doped diamond-like nanocomposite (DLN) a-C:H:Si:O films during ablation processing with linearly-polarized beams of a visible femtosecond laser (wavelength 515 nm, pulse duration 320 fs, pulse repetition rates 100 kHz-2 MHz, scanning beam velocity 0.05–1 m/s). The studies are focused on (i) laser ablation characteristics of Ti-DLN films at different pulse frequencies and constant fluence close to the ablation threshold, (ii) effects of the polarization angle rotation on the properties of low spatial frequency LIPSS (LSFL), and (iii) nanofriction properties of the ‘rotating’ LIPSS using atomic force microscopy (AFM) in a lateral force mode. It is found that (i) all LSFL are oriented perpendicular to the beam polarization direction, so being rotated with the beam polarization, and (ii) LSFL periods are gradually changed from 360 ± 5 nm for ripples parallel to the beam scanning direction to 420 ± 10 nm for ripples formed perpendicular to the beam scanning. The obtained results are discussed in the frame of the surface plasmon polaritons model of the LIPSS formation. Also, the findings of the nanoscale friction behavior, dependent on the LIPSS orientation relative to the AFM tip scanning direction, are presented and discussed.
Numerical Modelling of the Nonlinear Shear Creep Behavior of FRP-Concrete Bonded Joints
Authors: Soleilhet François , Quiertant Marc , Benzarti Karim
Published: January 2023

This paper presents a numerical investigation of the shear creep behavior of the adhesive joint in concrete structures strengthened by externally bonded fibre-reinforced polymers (FRP) composites. Based on experimental data collected in a previous study, creep constitutive equations were developed for the adhesive layer and implemented into a finite element code. The proposed model extends the classical one-dimensional formulation of Burgers creep model to a fully 3D model and introduces the nonlinearity of the model parameters. This numerical approach was first used to simulate the nonlinear creep behavior of bulk epoxy samples; it was then extended to predict the nonlinear creep response of the FRP-concrete interface in double lap shear specimens. Globally, a fair agreement was obtained between numerical results and experimental evidences. As a main result, it was found that creep induces a redistribution of the interfacial shear stress along the FRP-concrete lap joint, leading both to a stress relaxation near the loaded end of the adhesive joint and to an increase in the effective transfer length.
Analysis of the Vehicle Chassis Axle Fractures
Authors: Decker Živilė , Rudzinskas Vitalijus , Drozd Kazimierz , Caban Jacek , Tretjakovas Jurijus , Nieoczym Aleksander , Matijošius Jonas
Published: January 2023

With the rapid development of the road transport industry, trucks with semi-trailers have become the main means of transporting goods by road. High quality, durability and reliability of the construction are the main requirements for the production of trailers. Trailer and semi-trailer axles are one of the main and most important components of a truck. Due to the fact that semi-trailer axles are subjected to additional static and dynamic loads during operation, their proper construction is extremely important, therefore they should be carefully designed and tested. The durability of the suspension components refers to the duration of the onset of fatigue. This article presents an analysis of damage to the rear axle of the semi-trailer using macroscopic observations of the damage site and dynamic FEA of stress distribution in the axle material. In order to identify the probable cause of the damage, eight cases of loading the semi-trailer axle were considered. Analytical solutions have shown that in various cases the yield point is exceeded and the strength limit of the modeled semi-trailer axle is reached. The risk of damage to the vehicle’s suspension system components increases on poor roads (bumps and winding road sections).
Frequency Response Analysis for Three-Phase Star and Delta Induction Motors: Pattern Recognition and Fault Analysis Using Statistical Indicators
Authors: Al-Ameri Salem Mgammal , Abdul-Malek Zulkurnain , Salem Ali Ahmed , Noorden Zulkarnain Ahmad , Alawady Ahmed Allawy , Yousof Mohd Fairouz Mohd , Mosaad Mohamed Ibrahim , Abu-Siada Ahmed , Thabit Hammam Abdurabu
Published: January 2023

This paper presents a new investigation to detect various faults within the three-phase star and delta induction motors (IMs) using a frequency response analysis (FRA). In this regard, experimental measurements using FRA are performed on three IMs of ratings 1 HP, 3 HP and 5.5 HP in normal conditions, short-circuit fault (SC) and open-circuit fault (OC) conditions. The SC and OC faults are applied artificially between the turns (Turn-to-Turn), between the coils (Coil-to-Coil) and between the phases (Phase-to-Phase). The obtained measurements show that the star and delta IMs result in dissimilar FRA signatures for the normal and faulty windings. Various statistical indicators are used to quantify the deviations between the normal and faulty FRA signatures. The calculation is performed in three frequency ranges: low, middle and high ones, as the winding parameters including resistive, inductive and capacitive components dominate the frequency characteristics at different frequency ranges. Consequently, it is proposed that the boundaries for the used indicators facilitate fault identification and quantification.
Enhanced Reaching-Law-Based Discrete-Time Terminal Sliding Mode Current Control of a Six-Phase Induction Motor
Authors: Kali Yassine , Rodas Jorge , Doval-Gandoy Jesus , Ayala Magno , Gonzalez Osvaldo
Published: January 2023

This paper develops an inner stator current controller based on an enhanced reaching-law-based discrete-time terminal sliding mode. The problem of tracking stator currents with high accuracy while ensuring the robustness of a six-phase induction motor in the presence of uncertain electrical parameters and unmeasurable states is tackled. The unknown dynamics are approximated by using a time delay estimation method. Then, an enhanced power-reaching law is used to make each stage of the convergence faster. A stability analysis and the system controller’s finite-time convergence are demonstrated in detail. Practical work was conducted on an asymmetrical six-phase induction machine to illustrate the developed discrete approach’s robustness and effectiveness.