bluuebunny/crossref_metadata_2025 huggingface dataset:
The Interaction of Seasons and Biogeochemical Properties of Water Regulate the Air–Water CO2 Exchanges in Two Major Tropical Estuaries, Bay of Bengal (India)
Authors: Pattanaik Suchismita , Mohapatra Pradipta Kumar , Mohapatra Debasish , Swain Sanhita , Panda Chitta Ranjan , Dash Pradeep Kumar
Published: October 2022

The exchange of CO2 between the air–water interfaces of estuaries is crucial from the perspective of the global carbon cycle and climate change feedback. In this regard, we evaluated the air–water CO2 exchanges in two major estuaries—the Mahanadi estuary (ME) and the Dhamra estuary (DE) in the northern part of the Bay of Bengal, India. Biogeochemical properties of these estuarine waters were quantified in three distinct seasons, namely, pre-monsoon (March to May), monsoon (June to October), and post-monsoon (November to February). The significant properties of water, such as the water temperature, pH, salinity, nutrients, dissolved oxygen, chlorophyll-a (chl a), and photosynthetic pigment fluorescence of phytoplankton, were estimated and correlated with CO2 fluxes. We found that the ME acted as a source of CO2 fluxes in the monsoon and post-monsoon, while DE acted as a sink during the monsoon. The stepwise regression model showed that the fluxes were primarily driven by water temperature, pH, and salinity, and they correlated well with the phytoplankton characteristics. The chl a content, fluorescence yield, and phycobilisomes-to-photosystem II fluorescence ratios were major drivers of the fluxes. Therefore, for predicting air–water CO2 exchanges precisely in a large area over a seasonal and annual scale in the estuaries of the Bay of Bengal, India, critical key parameters such as water temperature, pH, salinity, chl a, and fluorescence yield of phytoplankton should be taken into consideration. However, the responses of phytoplankton, both in terms of production and CO2 capture, are critical research areas for a better understanding of air–water CO2 exchanges in coastal ecology under climate change scenarios.
Light-Driven Synthetic Biology: Progress in Research and Industrialization of Cyanobacterial Cell Factory
Authors: Li Chaofeng , Zheng Jiyang , Wu Yushuang , Wang Xiaotong , Shao Hui , Yan Dong
Published: October 2022

Light-driven synthetic biology refers to an autotrophic microorganisms-based research platform that remodels microbial metabolism through synthetic biology and directly converts light energy into bio-based chemicals. This technology can help achieve the goal of carbon neutrality while promoting green production. Cyanobacteria are photosynthetic microorganisms that use light and CO2 for growth and production. They thus possess unique advantages as “autotrophic cell factories”. Various fuels and chemicals have been synthesized by cyanobacteria, indicating their important roles in research and industrial application. This review summarized the progresses and remaining challenges in light-driven cyanobacterial cell factory. The choice of chassis cells, strategies used in metabolic engineering, and the methods for high-value CO2 utilization will be discussed.
Improving the Tolerance to Salinity Stress in Lettuce Plants (Lactuca sativa L.) Using Exogenous Application of Salicylic Acid, Yeast, and Zeolite
Authors: Babaousmail Mahfoud , Nili Mohammed S. , Brik Rania , Saadouni Mohammed , Yousif Sawsan K. M. , Omer Rihab M. , Osman Nahid A. , Alsahli Abdulaziz A. , Ashour Hatem , El-Taher Ahmed M.
Published: October 2022

Salinity is among the most limiting factors of crop production worldwide. This study aims to investigate the influence of the exogenous application of zeolite, yeast, and salicylic acid in alleviating the negative effect of salt stress under field conditions. Lettuce plants (Lactuca sativa L. cv. Batavia) were tested in a split-plot arrangement replicated three times. The salt stress was applied as a whole-plot factor in the concentrations (0 mM, 50 mM, 100 mM, and 150 mM NaCl). After 28 days of sowing, the plants were sprayed twice during the foliage growth with (control, salicylic acid 0.02%, yeast extract 3%, and zeolite 0.5%) as a split-plot factor. The length of roots and shoots, the number and area of leaves, and the biomass accumulation (dry and fresh weights) were measured 50 days after sowing. The concentrations of total soluble sugars, proline, Chlorophylls a and b in leaves have also been quantified. Salt stress significantly reduced the growth and the total chlorophyll of the lettuce plants (p < 0.05) and increased their proline and sugar contents’. Zeolite application improved the growth of lettuce at 0 and 50 mM NaCl, but at the highest salinity level only the number of leaves was improved by 15%. At a mild salinity stress, the application of salicylic acid has significantly (p < 0.05) increased the root length, height of plant, chlorophyll, and proline contents. Regarding the high stress levels (100 and 150 mM NaCl), yeast application showed the best tolerance to salinity stress by improving significantly most of the growth parameters (p < 0.05) but with lower proline, sugar, and chlorophyll contents. In general, foliar spray of yeast extract may offer a good alternative source of nutrients through leaves, leading to a better tolerance of the high salt stress exerted on roots.
The Predictive Role of the Upper-Airway Adipose Tissue in the Pathogenesis of Obstructive Sleep Apnoea
Authors: Molnár Viktória , Lakner Zoltán , Molnár András , Tárnoki Dávid László , Tárnoki Ádám Domonkos , Kunos László , Jokkel Zsófia , Tamás László
Published: October 2022

This study aimed to analyse the thickness of the adipose tissue (AT) around the upper airways with anthropometric parameters in the prediction and pathogenesis of OSA and obstruction of the upper airways using artificial intelligence. One hundred patients were enrolled in this prospective investigation, who were divided into control (non-OSA) and mild, moderately severe, and severe OSA according to polysomnography. All participants underwent drug-induced sleep endoscopy, anthropometric measurements, and neck MRI. The statistical analyses were based on artificial intelligence. The midsagittal SAT, the parapharyngeal fat, and the midsagittal tongue fat were significantly correlated with BMI; however, no correlation with AHI was observed. Upper-airway obstruction was correctly categorised in 80% in the case of the soft palate, including parapharyngeal AT, sex, and neck circumference parameters. Oropharyngeal obstruction was correctly predicted in 77% using BMI, parapharyngeal AT, and abdominal circumferences, while tongue-based obstruction was correctly predicted in 79% using BMI. OSA could be predicted with 99% precision using anthropometric parameters and AT values from the MRI. Age, neck circumference, midsagittal and parapharyngeal tongue fat values, and BMI were the most vital parameters in the prediction. Basic anthropometric parameters and AT values based on MRI are helpful in predicting OSA and obstruction location using artificial intelligence.
Toxic Megacolon Burdened with COVID-19 Coinfection—Worsening of an Unfavorable Diagnosis: A Single-Center Retrospective Study
Authors: Řezáč Tomáš , Klos Dušan , Stašek Martin , Vrba Radek , Zbořil Pavel , Špička Petr
Published: October 2022

Introduction: This study primarily sought to evaluate the risk factors for toxic megacolon development and treatment outcomes in Clostridium difficile-positive COVID-19 patients, secondarily to determining predictors of survival. Methods: During the second COVID-19 wave (May 2020 to May 2021), we identified 645 patients with confirmed COVID-19 infection, including 160 patients with a severe course in the intensive care unit. We selected patients with Clostridium difficile infection (CDI) (31 patients) and patients with toxic megacolon (9 patients) and analyzed possible risk factors. Results: Patients who developed toxic megacolon had a higher incidence (without statistical significance, due to small sample size) of cancer and chronic obstructive pulmonary disease, a higher proportion of them required antibiotic treatment using cephalosporins or penicillins, and there was a higher rate of extracorporeal circulation usage. C-reactive protein (CRP) and interleukin-6 values showed significant differences between the groups (CRP [median 126 mg/L in the non-toxic megacolon cohort and 237 mg/L in the toxic megacolon cohort; p = 0.037] and interleukin-6 [median 252 ng/L in the group without toxic megacolon and 1127 ng/L in those with toxic megacolon; p = 0.016]). As possible predictors of survival, age, presence of chronic venous insufficiency, cardiac disease, mechanical ventilation, and infection with Candida species were significant for increasing the risk of death, while corticosteroid and cephalosporin treatment and current Klebsiella infection decreased this risk. Conclusions: More than ever, the COVID-19 pandemic required strong up-to-date treatment recommendations to decrease the rate of serious in-hospital complications. Further studies are required to evaluate the interplay between COVID-19 and CDI/toxic megacolon.
Climate Stressors on Growth, Yield, and Functional Biochemistry of two Brassica Species, Kale and Mustard
Authors: Sehgal Akanksha , Reddy Kambham Raja , Walne Charles Hunt , Barickman T. Casey , Brazel Skyler , Chastain Daryl , Gao Wei
Published: October 2022

Due to climate change, the attainment of global food security is facing serious challenges in meeting the growing food demand. Abiotic stresses are the foremost limiting factors for agricultural productivity. However, not much information is available on the effect of multiple abiotic stresses on the morphological and biochemical aspects of kale and mustard. Therefore, an experiment was designed to study the effects of UV-B radiation, CO2 concentration, and high temperature on the growth, yield, and biochemistry of two Brassica species, namely B. oleracea L. var. acephala Winterbor F1 (hybrid kale) and B. juncea var. Green wave O.G. (mustard greens), which were grown under optimal nutrients and soil moisture conditions in soil–plant–atmosphere–research (SPAR) units. Two levels of UV-B radiation (0 and 10 kJ m−2 d−1), two concentrations of CO2 (420 and 720 ppm), and two different temperature treatments (25/17 °C and 35/27 °C) were imposed 12 days after sowing (DAS). Several morphological and biochemical parameters were measured at harvest (40 DAS) in both species. All the traits declined considerably under individual and multi-stress conditions in both species except under elevated CO2 levels, which had a positive impact. Marketable fresh weight decreased by 64% and 58% in kale and mustard plants, respectively, growing under UV-B treatment. A slight increase in the chlorophyll content was observed in both species under the UV-B treatment alone and in combination with high temperature and elevated CO2. Understanding the impacts of high temperature, CO2, and UV-B radiation treatments on leafy vegetables, such as kale and mustard, can help to improve existing varieties to enhance resilience towards environmental stresses while simultaneously improving yield, morphology, and biochemistry in plants.
The Rescue of the Romanian Health System by the Emergency Departments during the Fourth Wave of COVID-19 Pandemic
Authors: Oprita Bogdan , Davidoiu Andrei , Dinu Alexandru Bogdan , Oprita Ruxandra
Published: October 2022

The COVID-19 pandemic has led to the confrontation of the health system with the need to identify solutions for providing medical care to a very large number of patients. The main objective of our study was to describe the measures taken to provide optimal medical care to patients who presented themselves in one of the large emergency hospitals of Romania in the fourth wave of the COVID-19 pandemic. Material and Methods: We conducted a retrospective, observational study on a group of 1417 patients. The statistical analysis was performed using R. Results: The average length of stay of patients in the emergency departments was approximately 2.6 h, increasing to up to 15 days in some more severe cases. For rapid antigen tests, the highest positivity rate for SARS-CoV-2 was identified in patients aged >75 years (53%). Among the identified risk factors associated with the need for mechanical ventilation were advanced age (α < 0.001) and lack of vaccination against SARS-CoV-2 (α < 0.001). Discussion and conclusions: A method of saving the Romanian health system in full hospital bed occupancy conditions in the wards proved to be the provision of medical care in emergency departments.
Identification of Universally Applicable and Species-Specific Marker Peptides for Bacillus anthracis
Authors: Witt Natalie , Galante Domenico , Andreotti Sandro , Abdel Glil Mostafa , Fasanella Antonio , Meierhofer David , Tomaso Herbert
Published: October 2022

Anthrax is a zoonotic infection caused by the bacterium Bacillus anthracis (BA). Specific identification of this pathogen often relies on targeting genes located on two extrachromosomal plasmids, which represent the major pathogenicity factors of BA. However, more recent findings show that these plasmids have also been found in other closely related Bacillus species. In this study, we investigated the possibility of identifying species-specific and universally applicable marker peptides for BA. For this purpose, we applied a high-resolution mass spectrometry-based approach for 42 BA isolates. Along with the genomic sequencing data and by developing a bioinformatics data evaluation pipeline, which uses a database containing most of the publicly available protein sequences worldwide (UniParc), we were able to identify eleven universal marker peptides unique to BA. These markers are located on the chromosome and therefore, might overcome known problems, such as observable loss of plasmids in environmental species, plasmid loss during cultivation in the lab, and the fact that the virulence plasmids are not necessarily a unique feature of BA. The identified chromosomally encoded markers in this study could extend the small panel of already existing chromosomal targets and along with targets for the virulence plasmids, may pave the way to an even more reliable identification of BA using genomics- as well as proteomics-based techniques.
The Antioxidant, Analgesic, Anti-Inflammatory, and Wound Healing Activities of Haplophyllum tuberculatum (Forsskal) A. Juss Aqueous and Ethanolic Extract
Authors: Agour Abdelkrim , Mssillou Ibrahim , Es-safi Imane , Conte Raffaele , Mechchate Hamza , Slighoua Meryem , Amrati Fatima Ez-Zahra , Parvez Mohammad Khalid , Numan Omer , Bari Amina , Lyoussi Badiaa , Derwich Elhoussine
Published: October 2022

Herbal extracts are part of the solution to the increased demand for organic health care products. Traditionally, the different extracts prepared from Haplophyllum tuberculatum (Forsskal) A. Juss (H. tuberculatum) have been widely used to treat a wide range of illnesses. The aim of this study is to evaluate the antioxidant, analgesic, anti-inflammatory, and wound healing potential of the aqueous (HTAE) and ethanolic (HTEE) extracts of this plant as well as identify its major phytochemical components using LC-MS. Phytochemical analysis of both extracts revealed a rich composition and especially high amounts of glycosylic flavonols, 65.37% and 68.77% for the HTEE and HTAE, respectively. The antioxidant assays performed (DPPH, FRAP and TAC) indicated the excellent activity of the ethanolic extract while the in vivo activities (analgesic, anti-inflammatory, and healing potential) indicated the excellent activity of the aqueous extract. These findings support the therapeutic use of this plant by preventing pain and inflammation and promoting wound healing. To uncover, identify, and isolate compounds of potential medicinal and therapeutic significance, more studies on this species are required.
Disturbance in Some Fertility Biomarkers Induced and Changes in Testis Architecture by Chronic Exposure to Various Dosages of Each of Nonylphenol or Bisphenol A and Their Mix
Authors: Melebary Sahar J. , AlGhamdi Mariam S. , Elhalwagy Manal E. A. , Alsolmy Soha A. , Bin Dohaish Al Jawaher A.
Published: October 2022

This investigation was conducted to demonstrate the potential impacts of different doses of Bisphenol A (BPA) or Nonylphenol (NP) and their mixtures on some biological activities in male albino rats. Seventy male albino rats were allocated to the control group (GI) and were given 1 mL of ethanol. G II and G III were given 100 mg/kg of each of BPA and NP, G IV and G V were given 25 mg/kg of each of BPA and NP, G VI was given a high dose of BPA and NP, and G VII was given a low dose of BPA and NP. All animals were treated orally for 60 days. Serum biomarkers of oxidative stress, antioxidants, immune-inflammatory mediators, and apoptotic markers were determined, as well as a histopathological examination of the testis at the end of the experimental period. The results obtained showed a pronounced increase in malondialdehyde (MDA), protein carbonyl (PC), and 4-hydroxynonenol (4-HNE), concomitant with a significant reduction in serum Superoxide dismutase (SOD), catalase enzyme (CAT), and total antioxidant capacity (TAC) in all treated groups. A significant elevation in TNF Alpha, TNF Beta, and Caspase 3 serum was recorded individually and in the groups treated with high doses. The disturbance is represented by histological damage in the testis in the germinal epithelium and a decrease in spermatozoa inside the lumen of seminiferous tubules. The effects on testis tissues were dose-dependent, pronounced in mixture doses, and remarkable in higher doses. In conclusion, exposure to BPA and NP strongly impacts antioxidants, immune-inflammatory mediators, and testis tissue architecture. Furthermore, the data from this investigation support the idea that exposure to BPA and NP in daily life has multiple damages.
Two-Year Follow-Up on Chemosensory Dysfunction and Adaptive Immune Response after Infection with SARS-CoV-2 in a Cohort of 44 Healthcare Workers
Authors: Schambeck Sophia E. , Mateyka Laura M. , Burrell Teresa , Graf Natalia , Brill Ioana , Stark Thomas , Protzer Ulrike , Busch Dirk H. , Gerhard Markus , Riehl Henriette , Poppert Holger
Published: October 2022

Persistent chemosensory dysfunction (PCD) is a common symptom of long-COVID. Chemosensory dysfunction (CD) as well as SARS-CoV-2-specific antibody levels and CD8+ T-cell immunity were investigated in a cohort of 44 healthcare workers up to a median of 721 days after a positive PCR test. CD was assessed using questionnaires and psychophysical screening tests. After 721 days, 11 of 44 (25%) participants reported PCD, with five describing an impaired quality of life. One participant reported hyperosmia (increased sense of smell). The risk of PCD at 721 days was higher for participants reporting qualitative changes (parosmia (altered smell), dysgeusia (altered taste), or phantosmia (hallucination of smell)) during initial infection than in those with isolated quantitative losses during the first COVID-19 infection (62.5% vs. 7.1%). The main recovery rate occurred within the first 100 days and did not continue until follow-up at 2 years. No correlation was found between antibody levels and CD, but we observed a trend of a higher percentage of T-cell responders in participants with CD. In conclusion, a significant proportion of patients suffer from PCD and impaired quality of life 2 years after initial infection. Qualitative changes in smell or taste during COVID-19 pose a higher risk for PCD.
C-Reactive Protein as a Potential Peripheral Biomarker for High-Lethality Suicide Attempts
Authors: Aguglia Andrea , Natale Antimo , Fusar-Poli Laura , Gnecco Giovanni Battista , Lechiara Alessio , Marino Margherita , Meinero Matteo , Pastorino Fabrizio , Costanza Alessandra , Spedicato Giorgio Alfredo , Amerio Andrea , Serafini Gianluca , Aguglia Eugenio , Amore Mario
Published: October 2022

The aim of the present study was to identify a cut-off of c-reactive protein (c-RP) potentially predictive of high-lethality suicide attempts (SA) in an inpatient psychiatric sample. After attempting suicide, subjects were admitted to the emergency ward of the IRCCS Ospedale Policlinico San Martino and later to the section of Psychiatry from 1 August 2013 to 31 July 2018. C-reactive protein was measured. The Area Under the Receiver Operating Characteristic (ROC_AUC) was used to assess the discriminative capacity of c-RP for high- vs. low-lethality SA, and a logistic regression was performed to detect the odds ratio, adjusted for age and sex. High-lethality suicide attempters were 133 (30.8%), while low-lethality suicide attempters were 299 (69.2%). The optimal cut-off threshold (and corresponding sensitivity and specificity values) for c-RP was 4.65 mg/L (68/71%). This cut-off corresponds to an AUC of 73.5%. An odds ratio of 4.70 was generated for current high-lethality SA after a logistic regression, adjusted for age and sex. Research on social and biological factors underlying the lethality of SA is crucial for a better understanding of this complex phenomenon. Identifying potential predictors of SA, especially those at high lethality, is essential to implement personalized preventive strategies.
One Carbon Metabolism and S-Adenosylmethionine in Non-Alcoholic Fatty Liver Disease Pathogenesis and Subtypes
Authors: Fernández-Ramos David , Lopitz-Otsoa Fernando , Millet Oscar , Alonso Cristina , Lu Shelly C. , Mato José M.
Published: October 2022

One carbon metabolism (1CM) can be defined as the transfer of a carbon unit from one metabolite to another and its replenishment by different sources of labile methyl-group nutrients: primarily choline, methionine, betaine, and serine. This flow of carbon units allows the biosynthesis of nucleotides, amino acids, formylated methionyl-tRNA, polyamines, glutathione, phospholipids, detoxification reactions, maintenance of the redox status and the concentration of NAD, and methylation reactions including epigenetic modifications. That is, 1CM functions as a nutrient sensor and integrator of cellular metabolism. A critical process in 1CM is the synthesis of S-adenosylmethionine (SAMe), the source of essentially all the hundreds of millions of daily methyl transfer reactions in a cell. This versatility of SAMe imposes a tight control in its synthesis and catabolism. Much of our knowledge concerning 1CM has been gained from studies in the production and prevention of nonalcoholic fatty liver disease (NAFLD). Here, we discuss in detail the function of the most important enzymes for their quantitative contribution to maintaining the flux of carbon units through 1CM in the liver and discuss how alterations in their enzymatic activity contribute to the development of NAFLD. Next, we discuss NAFLD subtypes based on serum lipidomic profiles with different risk of cardiovascular disease. Among the latter, we highlight the so-called subtype A for its serum lipidomic profile phenocopying that of mice deficient in SAMe synthesis and because its high frequency (about 50% of the NAFLD patients).
Experimental Investigation of Tribological Properties of Two Fully Formulated Engine Oils with Additional Nanoscale Spherical Zirconia Particles
Authors: Kuti Rajmund , Szabó Ádám István , Tóth Álmos Dávid
Published: October 2022

Decreasing harmful emissions of vehicle engines is becoming more and more challenging due to stricter standards. A possible solution is to improve the tribological attributes of lubricants, which can be achieved through the application of appropriate additives. According to preliminary studies conducted by the authors, ZrO2 (zirconium-dioxide) nano-sized ceramic particles as lubricant additives have overwhelmingly positive tribological attributes in the presence of non-metallic superficial materials. Additive concentration, as well as cross-effects with other additives were investigated in order to determine a formulation resulting in optimal tribological attributes. In this paper, the experimental investigation of ZrO2 nano-ceramic powder as a lubricant additive is presented. The tribological performance of individually samples were experimentally investigated on a ball-on-disc translational tribometer. The experiments revealed an optimal additive content of 0.3 wt%. Increasing the quantity of additives further ruined friction and wear properties of the examined tribological system.
Research Progress of High-Speed Wheel–Rail Relationship
Authors: Jin Xuesong
Published: October 2022

The research on wheel–rail relationship includes the basic theoretical models and corresponding numerical methods of wheel–rail in rolling contact, geometric parameter matching and material matching of them, friction and wear, wheel–rail rolling contact fatigue, wheel–rail adhesion and noise. They are also key theoretical and technical problems of the high-speed train/track coupling system. The basic theoretical models of wheel–rail in rolling contact and the corresponding numerical methods are the basis and one of the basic means for solving other wheel–rail relationship problems. The other is the experimental means. Moreover, the modeling and analysis of coupling behavior of the train and track can only be realized by means of the wheel–rail rolling contact mechanics model and its corresponding numerical method. This paper mainly discusses some research work and achievements on high-speed wheel–rail relationship problems since China opened a high-speed railway system on a large scale. The discussions in this paper include the classic wheel–rail rolling contact theoretical models (analytical forms) and the modern wheel–rail rolling contact theories (numerical methods), their advantages and disadvantages, their application and future development direction of them. The reviewed research progress on the other wheel–rail relationships mainly expounds the thorny problems of the wheel–rail relationship encountered in the operation of China’s high-speed railway, how to adopt new theoretical analysis methods, test means and take effective measures to solve these problems. It also includes research results of similar important reference values performed by international peer experts in related fields. Challenging and unsolved problems in high-speed wheel–rail relationship research are also reviewed in the full text.
N-Benzyl-N-(2-hydroxyethyl)-2-(oxazolidin-2-on-3-yl)-2-phenylacetamide
Authors: Aitken R. Alan , Logan Joe S. , Slawin Alexandra M. Z.
Published: October 2022

The title compound, obtained by base-induced dimerization of 3-benzyloxazolidin-2-one, has been prepared and fully characterised. Its X-ray structure features hydrogen-bonded dimers involving the hydroxyl OH and amide carbonyl, forming a 14-membered ring.
Hydrodesulfurization of Dibenzothiophene over Ni-Mo-W Sulfide Catalysts Supported on Sol-Gel Al2O3-CeO2
Authors: Navarro Yerga Rufino M. , Pawelec Barbara , Mota Noelia , Huirache-Acuña Rafael
Published: October 2022

To achieve sulfur content in gas oil at a near-zero level, new catalysts with improved hydrogenation functions are needed. In this work, new Ni-Mo-Mo hydrodesulfurization (HDS) catalysts supported by Al2O3-CeO2 materials were synthesized to evaluate their efficiency in the reaction of HDS with dibenzothiophene (DBT). Al2O3-CeO2 supports different CeO2 loadings (0, 5, 10 and 15 wt.%) and supported NiMoW catalysts were synthesized by sol-gel and impregnation methods, respectively. The physicochemical properties of the supports and catalysts were determined by a variety of techniques (chemical analysis, XRD, N2 physisorption, DRS UV-Vis, XPS, and HRTEM). In the DBT HDS reaction carried out in a batch reactor at 320 °C and a H2 pressure of 5.5 MPa, the sulfide catalysts showed a dramatic increase in activity with increasing CeO2 content in the support. Nearly complete DBT conversion (97%) and enhanced hydrogenation function (HYD) were achieved on the catalyst with the highest CeO2 loading. The improved DBT conversion and selectivity towards the hydrogenation products (HYD/DDS ratio = 1.6) of this catalyst were attributed to the combination of the following causes: (i) the positive effect of CeO2 in forcing the formation of the onion-shaped Mo(W)S2 layers with a large number of active phases, (ii) the inhibition of the formation of the undesired NiAlO4 spinel phase, (iii) the appropriate textural properties, (iv) the additional ability for heterolytic dissociation of H2 on the CeO2 surfaces, and (v) the increase in Brønsted acidity.
Metal Knitting: A New Strategy for Cold Gas Spray Additive Manufacturing
Authors: Vaz Rodolpho F. , Albaladejo-Fuentes Vicente , Sanchez Javier , Ocaña Unai , Corral Ziortza G. , Canales Horacio , Cano Irene G.
Published: October 2022

Cold Spray Additive Manufacturing (CSAM) is an emergent technique to produce parts by the additive method, and, like other technologies, it has pros and cons. Some advantages are using oxygen-sensitive materials to make parts, such as Ti alloys, with fast production due to the high deposition rate, and lower harmful residual stress levels. However, the limitation in the range of the parts’ geometries is a huge CSAM con. This work presents a new conceptual strategy for CSAM spraying. The controlled manipulation of the robot arm combined with the proper spraying parameters aims to optimize the deposition efficiency and the adhesion of particles on the part sidewalls, resulting in geometries from thin straight walls, less than 5 mm thick, up to large bulks. This new strategy, Metal Knitting, is presented regarding its fundamentals and by comparing the parts’ geometries produced by Metal Knitting with the traditional strategy. The Metal Knitting described here made parts with vertical sidewalls, in contrast to the 40 degrees of inclination obtained by the traditional strategy. Their mechanical properties, microstructures, hardness, and porosity are also compared for Cu, Ti, Ti6Al4V, 316L stainless steel, and Al.
The Effect of Repeated Pressing on the Flexural Strength, Color Stability, Vickers Hardness, and Surface Topography of Heat-Pressed Lithium Disilicate
Authors: AbuHaimed Tariq S. , Alzahrani Saeed J. , Farsi Sami A. , AL-Turki Lulwa E. , Hajjaj Maher S.
Published: October 2022

The aim of this study was to investigate the effect of repressing leftover heat-pressed lithium disilicate material on its mechanical and optical properties. A lithium disilicate ingot (IPS e.max® Press, IvoclarVivadent, Schaan, Liechtenstein) shade (A1) low translucency was first heat-pressed to yield ceramic bars and disks. Then, the second and third presses were fabricated from the leftovers of the previous pressing cycles. A total of 36 bars and 15 disk specimens were fabricated and divided into three groups according to the number of pressing cycles (n = 12 bars and n = 5 disks): P1: first press (control), P2: second press, and P3: third press. The specimens were tested for flexural strength, color change, Vickers hardness, and surface topography under scanning electron microscopy. One-way ANOVA testing was used to evaluate flexural strength and hardness, while an independent t-test was performed to evaluate color change. There was no significant difference in flexural strength as the number of heat-pressed cycles increased (p = 0.283). Similarly, there was no significant difference in the microhardness values between all groups (p = 0.220). The overall color change ∆E between P1–P2 and P1–P3 were 2.01 and 2.14, respectively. The SEM images showed evenly distributed and densely packed lithium disilicate crystals in the P1 group. However, larger and less densely packed crystals were noticeable in P2 and P3. The IPS e.max Press could be repressed up to two times without an adverse effect on mechanical properties or color stability. These results may support the reuse of pressed lithium disilicate for economical purposes, but further clinical evaluation should be conducted to confirm these findings.
Mechanical Behaviour and Morphology of Thixoformed Aluminium Alloy Reinforced by Graphene
Authors: Md Ali Afifah , Omar Mohd Zaidi , Salleh Mohd Shukor , Hashim Hanizam , Mohamed Intan Fadhlina , Wakhi Anuar Nur Farah Bazilah
Published: October 2022

Thixoforming is a promising method that offers several advantages over both liquid and solid processing. This process utilizes semi-solid behaviour and reduces macrosegregation, porosity and forming forces during the shaping process. Microstructural and mechanical characterization of 0.3, 0.5 and 1.0 wt% graphene nanoplatelet (GNP) reinforced A356 aluminium alloy composite fabricated by thixoforming was investigated. Stir casting was employed to fabricate feedstocks before they were thixoformed at 50% liquid. The microstructure was characterized and evaluated by field emission scanning electron microscopy with an energy dispersive X-ray detector and X-ray diffraction. Mechanical testing, such as microhardness and tensile testing, was also performed to estimate the mechanical properties of the composites. The incorporation of 0.3 wt.% GNPs in Al alloy increased by about 27% in ultimate tensile strength and 29% in hardness. The enhancement in tensile strength is primarily attributed to load transfer strengthening due to the uniform dispersion of these GNPs within the Al matrix, which promotes effective load transfer during tensile deformation, and GNPs’ wrinkled surface structure. Simultaneously, the addition of GNPs enhances the grain refinement effect of the Al alloy matrix, resulting in a grain size strengthening mechanism of the GNPs/Al composites. The results reveal that thixoformed composite microstructure consists of uniformly distributed GNPs, α-Al globules and fine fibrous Si particles. The composites’ grains were refined and equiaxed, and the mechanical properties were improved significantly. This study creates a new method for incorporating GNPs into Al alloy for high-performance composites.
Parametric Study of the Numerical Model of a Bolted Connection of Steel Structure for Photovoltaic Panels
Authors: Mrówczyński Damian , Gajewski Tomasz , Garbowski Tomasz
Published: October 2022

In the face of the reality that unexpectedly mobilized the governments of most central European countries (including Poland), the development of renewable energy sources (RES) seems to be an important direction. Therefore, both wind parks and solar farms will be constructed at double speed for energetic independence. This urgency makes the market of producers of structures for mounting solar panels also need to adapt quickly to the new situation. New constructions adapted to quick assembly with the use of nutless screw connections seem to be one of the best solutions. These structures must not only be easy and quick to install but also durable, which makes the connections resistant to cyclical loads. The speed of assembly of the substructure can be achieved precisely with the help of nutless connections, but their durability should be carefully analyzed. This article presents parametric analyses of the numerical model of this type of connection. The selection of appropriate numerical models for simulation is of key importance in the fatigue strength analysis of bolted connections. This article investigates two different models used in numerical fatigue analyses performed in the Abaqus FEA and FE-Safe program, namely, traditional bolt with nut and innovative self-tapping nutless bolt. Extended parametric analyses of both numerical models were carried out, which ultimately allowed optimization of the fatigue capacity of the connection.
Special Issue: Corrosion Properties and Mechanism of Steels
Authors: Křivý Vít
Published: October 2022

The economic losses caused by corrosion are estimated to be 3–5% of gross domestic product in developed countries [...]
Regulating the Configurational Entropy to Improve the Thermoelectric Properties of (GeTe)1−x(MnZnCdTe3)x Alloys
Authors: Huang Yilun , Zhi Shizhen , Zhang Shengnan , Yao Wenqing , Ao Weiqin , Zhang Chaohua , Liu Fusheng , Li Junqin , Hu Lipeng
Published: October 2022

In thermoelectrics, entropy engineering as an emerging paradigm-shifting strategy can simultaneously enhance the crystal symmetry, increase the solubility limit of specific elements, and reduce the lattice thermal conductivity. However, the severe lattice distortion in high-entropy materials blocks the carrier transport and hence results in an extremely low carrier mobility. Herein, the design principle for selecting alloying species is introduced as an effective strategy to compensate for the deterioration of carrier mobility in GeTe-based alloys. It demonstrates that high configurational entropy via progressive MnZnCdTe3 and Sb co-alloying can promote the rhombohedral-cubic phase transition temperature toward room temperature, which thus contributes to the enhanced density-of-states effective mass. Combined with the reduced carrier concentration via the suppressed Ge vacancies by high-entropy effect and Sb donor doping, a large Seebeck coefficient is attained. Meanwhile, the severe lattice distortions and micron-sized Zn0.6Cd0.4Te precipitations restrain the lattice thermal conductivity approaching to the theoretical minimum value. Finally, the maximum zT of Ge0.82Sb0.08Te0.90(MnZnCdTe3)0.10 reaches 1.24 at 723 K via the trade-off between the degraded carrier mobility and the improved Seebeck coefficient, as well as the depressed lattice thermal conductivity. These results provide a reference for the implementation of entropy engineering in GeTe and other thermoelectric materials.
A Novel Friction Stir Deposition Technique to Refill Keyhole of Friction Stir Spot Welded AA6082-T6 Dissimilar Joints of Different Sheet Thicknesses
Authors: Ahmed Mohamed M. Z. , El-Sayed Seleman Mohamed M. , Ahmed Essam , Reyad Hagar A. , Alsaleh Naser A. , Albaijan Ibrahim
Published: October 2022

Joining dissimilar sheet thicknesses of AA6082-T6 alloys by friction stir spot welding (FSSW) provides many advantages in automotive and aerospace applications. The formed keyhole at the end of the FSSW process is one of the typical features after the welding process, which owns the same size as the rotating pin that remains at the joint center. This keyhole destroys the joint continuity and can stimulate serious stress concentration when the FSSW joint bears an external force. To solve this issue, a novel refilling technique was developed for the FSSW keyholes using a friction stir deposition (FSD) technique. The FSSW joints of AA6082-T6 sheets were welded at various rotation speeds from 400 to 1000 rpm and a constant dwell time of 3 s, where a 2 mm sheet thickness was an upper sheet, and a 1 mm sheet thickness was a lower sheet. All the keyhole refilling processes were achieved using a specially designed AA2011-T6 consumable rod to be used for friction stir deposition of continuous layers at a constant deposition parameter of 400 rpm consumable rod rotation speed and a 1 mm/min feed rate. The heat input energy for both the FSSW and refilled FSSW lap joints was calculated. In addition, the FSSW and the FSD temperatures were measured. Macrostructure, microstructure, and mechanical properties in terms of hardness and tensile shear maximum load were evaluated for both the friction stir spot welded (FSSWed) and the refilled FSSW lap joints. The obtained results showed that the keyhole could be successfully refilled with defect-free continuous multilayers after the refill friction stir spot welding (RFSSW) process. All the RFSSW lap joints showed higher tensile shear loads than that given by the FSSW (before refill) lap joints. The RFSSW joint (welded at 600 rpm/3 s and refilled at 400 rpm/1 mm/min) showed a higher tensile shear load of 5400 N ± 100 compared with that recorded by the unrefilled joint (4300 N ± 80). The fracture location and fracture surface of the FSSW and RFSSW were examined and discussed.
Nonlocal Free Vibration of Embedded Short-Fiber-Reinforced Nano-/Micro-Rods with Deformable Boundary Conditions
Authors: Civalek Ömer , Uzun Büşra , Yaylı Mustafa Özgür
Published: October 2022

An efficient eigenvalue algorithm is developed for the axial vibration analysis of embedded short-fiber-reinforced micro-/nano-composite rods under arbitrary boundary conditions. In the formulation, nonlocal elasticity theory is used to capture the size effect, and the deformable boundary conditions at the ends are simulated using two elastic springs in the axial direction. In addition, to determine the reinforcing effect of restrained nano-/micro-rods, a new system of linear equations with the concept of the infinite power series is presented. After performing the mathematical processes known as Fourier sine series, Stokes’ transformation and successive integration, we finally obtain a coefficient matrix in terms of infinite series for various rigid or deformable boundary conditions. Some accurate eigenvalue solutions of the free axial vibration frequencies of the short-fiber-reinforced micro-/nano-composite rods with and without being restrained by the means of elastic springs are given to show the performance of the present method. The presence of the elastic spring boundary conditions changes the axial vibration frequencies and corresponding mode shapes.
Viscoelastic and Electromagnetic Materials with Nonlinear Memory
Authors: Giorgi Claudio , Golden John Murrough
Published: October 2022

A method is presented for generating free energies relating to nonlinear constitutive equations with memory from known free energies associated with hereditary linear theories. Some applications to viscoelastic solids and hereditary electrical conductors are presented. These new free energies are then used to obtain estimates for nonlinear integro-differential evolution problems describing the behavior of nonlinear plasmas with memory.
Numerical Analysis on Transverse Splicing Structure for the Widening of a Long Multi-Span Highway Concrete Continuous Box Girder Bridge
Authors: Wu Wenqing , Zhang Hui , Liu Zheng , Wang Yunpeng
Published: October 2022

For the bridge widening of long multi-span highway concrete continuous box girder with a conventional splicing structure, due to the large longitudinal difference deformation by concrete shrinkage and creep between the existing and new ones, the widened structure will have an overlarge bending deformation after widening, especially an obvious transverse deformation at the end of girder, which will lead to structural damage to the newly widened structure. To effectively absorb the difference deformation mentioned above, this study proposes a novel transverse splicing structure based on the folding effect of a corrugated steel plate (CSP) (hereinafter referred to as “the CSP splicing structure”). Then, a finite element structural analysis was performed on the mechanical properties of the widened structure with the CSP splicing structure, and compared to those of a widened structure adopting the conventional concrete splicing mode, to clarify the transverse load transferring mechanism of the structure. Finally, by conducting a sensitivity analysis on CSP thickness, corrugation length, splicing stitch width, and other structural parameters, a sound parameter combination scheme was put forward. According to the research results, to ensure effective utilization of the CSP folding effect, the corrugation pattern direction of CSP should be set as horizontal, and the wave angle as the degree of 90°. In addition, it mitigated the transverse tensile stress to effectively avoid concrete cracking feasibility on the top flange of the box girder at the end of the girder. This study offers a feasible way of avoiding the structural damage produced by an excess transverse deformation at the end of the girder after bridge widening of a long multi-span concrete continuous box girder.
Experimental Study of the Damage and Failure Characteristics of the Backfill-Surrounding Rock Contact Zone
Authors: Li Guang , Wan Yang , Guo Jie , Ma Fengshan , Zhao Haijun , Wu Yanfang
Published: October 2022

Due to obvious differences in the properties of the filling body and surrounding rock, deformation always develops near the contact zone. Thus, determining the damage and failure characteristics of the contact zone between the backfill and surrounding rock is a precondition for safe production in mines. Taking Jinchuan mine as study area, the backfill-surrounding rock contact zones are divided into three models according to their different geometric shapes, namely, a linear model, embedded model, and multiple broken line model. A combined numerical simulation and physical model test method was adopted in this study. The research results show that the damage in the linear model begins at the seam, the failure is mainly concentrated in the filling body, and shear failure is dominant. The damage in the embedded model initially occurs around the inflection points, while the damage in the multiple broken line model initially occurs at the seams, and cracks always appear on the vertical contact surface first. Among the three contact models, the stability increases as follows: embedded > multiple broken line > linear. Moreover, the filling body enclosed by surrounding rock is the most stable, and the surrounding rock located in the footwall is more stable than the filling body located in the footwall. The conclusions of this study provide a theoretical basis for designing a mining scheme for Jinchuan mine and other mines with similar geological conditions and mining methods, and they provide a reference for studying the mechanical properties and stability of composite materials.
Numerical Investigation of the Temperature Field Effect on the Mechanical Responses of Conventional and Cool Pavements
Authors: Liu Pengfei , Kong Xiangrui , Du Cong , Wang Chaohe , Wang Di , Oeser Markus
Published: October 2022

Conventional asphalt pavement has a deep surface color and large thermal inertia, which leads to the continuous absorption of solar thermal radiation and the sharp rise of surface temperature. This can easily lead to the permanent deformation of pavement, as well as aggravate the urban heat island (UHI) effect. Cool pavement with a reflective coating plays an important role in reducing pavement temperature and alleviating the UHI effect. It is of great significance to study the influence of temperature on the mechanical response of different types of pavement under vehicle loading. Therefore, this study examined the heat exchange theory between pavement and the external environment and utilized the representative climate data of a 24 h period in the summer. Two kinds of three-dimensional finite element models were established for the analysis of temperature distribution and the mechanical responses of conventional pavement and cool pavement. The results show that in this environmental condition, conventional pavement temperatures can exceed 50 °C under high temperatures in summer, which allows for the permanent deformation of pavement and further affects the service life of asphalt pavement. The temperature difference in a conventional pavement surface between 6 h (24.7 °C) and 22 h (30.2 °C) is much less than that between 22 h (30.2 °C) and 13 h (50.1 °C) in the summer. However, the difference in the vertical displacements of the pavement surface between 6 h and 22 h is much larger than that between 22 h and 13 h. One reason is that the difference in temperature distribution between the morning and night leads to changes in pavement structure stiffness, resulting in significant differences in vertical displacement. Cool pavement has a significant cooling effect, which can reduce the surface temperature of a road by more than 15 °C and reduce the vertical displacement of the pavement by approximately 11.3%, which improves the rutting resistance of the pavement. However, the use of cool pavement will not change the horizontal strain at the bottom of the asphalt base and will not improve the fatigue resistance of asphalt pavement. This research will lay the foundation for further clarifying the difference in the mechanical properties between the two types of pavements in the management and maintenance stage.