bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-Healing Concrete as a Prospective Construction Material: A Review
Authors: Amran Mugahed , Onaizi Ali M. , Fediuk Roman , Vatin Nikolai Ivanovicn , Muhammad Rashid Raizal Saifulnaz , Abdelgader Hakim , Ozbakkaloglu Togay
Published: April 2022

Concrete is a material that is widely used in the construction market due to its availability and cost, although it is prone to fracture formation. Therefore, there has been a surge in interest in self-healing materials, particularly self-healing capabilities in green and sustainable concrete materials, with a focus on different techniques offered by dozens of researchers worldwide in the last two decades. However, it is difficult to choose the most effective approach because each research institute employs its own test techniques to assess healing efficiency. Self-healing concrete (SHC) has the capacity to heal and lowers the requirement to locate and repair internal damage (e.g., cracks) without the need for external intervention. This limits reinforcement corrosion and concrete deterioration, as well as lowering costs and increasing durability. Given the merits of SHCs, this article presents a thorough review on the subject, considering the strategies, influential factors, mechanisms, and efficiency of self-healing. This literature review also provides critical synopses on the properties, performance, and evaluation of the self-healing efficiency of SHC composites. In addition, we review trends of development in research toward a broad understanding of the potential application of SHC as a superior concrete candidate and a turning point for developing sustainable and durable concrete composites for modern construction today. Further, it can be imagined that SHC will enable builders to construct buildings without fear of damage or extensive maintenance. Based on this comprehensive review, it is evident that SHC is a truly interdisciplinary hotspot research topic integrating chemistry, microbiology, civil engineering, material science, etc. Furthermore, limitations and future prospects of SHC, as well as the hotspot research topics for future investigations, are also successfully highlighted.
Quo Vadis, Nanothermite? A Review of Recent Progress
Authors: Polis Mateusz , Stolarczyk Agnieszka , Glosz Karolina , Jarosz Tomasz
Published: April 2022

One of the groups of pyrotechnic compositions is thermite compositions, so-called thermites, which consist of an oxidant, usually in the form of a metal oxide or salt, and a free metal, which is the fuel. A characteristic feature of termite combustion reactions, apart from their extremely high exothermicity, is that they proceed, for the most part, in liquid and solid phases. Nanothermites are compositions, which include at least one component whose particles size is on the order of nanometers. The properties of nanothermites, such as high linear burning velocities, high reaction heats, high sensitivity to stimuli, low ignition temperature, ability to create hybrid compositions with other high-energy materials allow for a wide range of applications. Among the applications of nanothermites, one should mention igniters, detonators, microdetonators, micromotors, detectors, elements of detonation chain or elements allowing self-destruction of systems (e.g., microchips). The aim of this work is to discuss the preparation methods, research methods, direction of the future development, eventual challenges or problems and to highlight the applications and emerging novel avenues of use of these compositions.
Optimal Design and Competitive Spans of Timber Floor Joists Based on Multi-Parametric MINLP Optimization
Authors: Jelušič Primož , Kravanja Stojan
Published: April 2022

This study investigates the optimization of the design of timber floor joists, taking into account the self-manufacturing costs and the discrete sizes of the structure. This non-linear and discrete class of optimization problem was solved with the multi-parametric mixed-integer non-linear programming (MINLP). An MINLP optimization model was developed. In the model, an accurate objective function of the material and labor costs of the structure was subjected to design, strength, vibration and deflection (in)equality constraints, defined according to Eurocode regulations. The optimal design of timber floor joists was investigated for different floor systems, different materials (sawn wood and glulam), different load sharing systems, different vertical imposed loads, different spans, and different alternatives of discrete cross-sections. For the above parameters, 380 individual MINLP optimizations were performed. Based on the results obtained, a recommended optimal design for timber floor joists was developed. Engineers can select from the recommendations the optimal design system for a given imposed load and span of the structure. Economically suitable spans for timber floor joists structures were found. The current knowledge of competitive spans for timber floor joists is extended based on cost optimization and Eurocode standards.
Enhancement of Confinement in Scaled RC Columns using Steel Fibers Extracted from Scrap Tyres
Authors: Ahmad Izaz , Iqbal Mudasir , Abbas Asim , Badrashi Yasir Irfan , Jamal Arshad , Ullah Shahid , Yosri Ahmed M. , Hamad Moustafa
Published: April 2022

Steel fibers are widely extracted from scrap tyres, causing environmental concerns. This paper presents the use of steel fibers in variable proportions extracted from scrap tyres. The enhancement of the confinement was envisaged through the addition of steel fibers obtained from scrap tyres. The study included an experimental program for the development of constitutive material models for ordinary Portland cement (OPC) concrete and concrete with added steel fibers. A mix design was carried out for OPC, targeting a compressive strength of 3000 psi. Steel fibers were added to OPC in ratios of 1.0% to 3.0%, with an increment of 0.5%. Concrete columns, with cross-sectional dimensions of 6 × 6 inches and a length of 30 inches, were cast with both OPC and fiber-reinforced concrete. The column confinement was evaluated with a different spacing of ties (3- and 4-inch center-to-center). Compression tests on the concrete columns indicate that the addition of steel fibers to a concrete matrix results in an appreciable increase in strength and ductility. Overall, increasing the percentage of steel fibers increased the compression strength and the ductility of concrete. The maximum strain in the concrete containing 2.5% steel fibers increased by 285% as compared to the concrete containing 1% of steel fibers. An optimum percentage of 2.5% steel fibers added to the concrete resulted in a 39% increase in compressive strength, accompanied by a significant improvement in ductility. The optimum content of steel fibers, when used in confined columns, showed that confined compression strength increased with the addition of steel fibers. However, it is recommended that additional columns on the basis of the optimum steel fiber content shall be tested to evaluate their effectiveness in reducing the stirrup spacing.
Advances in Titanium/Polymer Hybrid Joints by Carbon Fiber Plug Insert: Current Status and Review
Authors: Faudree Michael , Uchida Helmut , Kimura Hideki , Kaneko Satoru , Salvia Michelle , Nishi Yoshitake
Published: April 2022

A literature review of up-to-date methods to strengthen Ti/carbon-fiber-reinforced polymer (CFRP) hybrid joints is given. However, there are little or no studies on Ti/CFRP joints by carbon fiber plug insert, which takes advantage of the extremely high surface adhesion area of ~6 μm CFs. Therefore, we cover the current status and review our previously published results developing hybrid joints by a CF plug insert with spot-welded Ti half-lengths to enhance the safety levels of aircraft fan blades. A thermoset Ti/CF/epoxy joint exhibited an ultimate tensile strength (UTS) of 283 MPa when calculated according to the rule of mixtures (RM) for the CF cross-section portion. With concern for the environment, thermoplastic polymers (TPs) allowed recyclability. However, a drawback is easy CF pull-out from difficult-to-adhere TPs due to insufficient contact sites. Therefore, research on a novel method of homogeneous low voltage electron beam irradiation (HLEBI) to activate a bare CF half-length prior to dipping in a TP resin was reviewed and showed that the UTS by the RM of Ti/EBCF/acrylonitrile butadiene styrene (ABS) and Ti/EBCF/polycarbonate (PC) joints increased 154% (from 55 to 140 MPa) and 829% (from 30 to 195 MPa), respectively, over the untreated sample. The optimum 0.30 MGy HLEBI prevented CF pull-out by apparently growing crystallites into the TP around the CF circumference, raising the UTS amount closer to that of epoxy.
Optimization-Based Economical Flexural Design of Singly Reinforced Concrete Beams: A Parametric Study
Authors: Azam Rizwan , Riaz Muhammad Rizwan , Farooq Muhammad Umer , Ali Faraz , Mohsan Muhammad , Deifalla Ahmed Farouk , Mohamed Abdeliazim Mustafa
Published: April 2022

In the past, many studies have been conducted on the optimization of reinforced concrete (RC) structures. These studies have demonstrated the effectiveness of different optimization techniques to obtain an economical design. However, the use of optimization techniques to an obtain economical design is not so practical due to the difficulty in applying most of the optimization techniques to achieve an optimal solution. The RC beam is one of the most common structural elements encountered by a practising design engineer. The current study is designed to highlight the potential of the Solver tool in MS Excel as an easy-to-use option for optimizing the design of simply supported RC beams. A user-friendly interface was developed in a spreadsheet in which beam design parameters from a typical design can be entered and an economical design can be obtained using the Evolutionary Algorithm available in the MS Excel Solver tool. To demonstrate the effectiveness of the developed optimization tool, three examples obtained from the literature have been optimized. The results showed that up to 24% economical solution can be obtained by keeping the same material strengths that were assumed in the original design. However, if material strength is also considered as a variable, up to 44% of the economical solution can be obtained. A parametric study was also conducted to investigate the effect of different design variables on the economical design of simply supported RC beams and to derive useful rules of thumb for their design and proportioning, with the objective of cost minimization. The results of the parametric study suggest that the grade of the reinforcing steel is one of the most influential factors that affect the cost of simply supported RC beams. Practicing engineers can use the trends derived from this research to further refine their optimal designs.
Indirect Measurement of Electron Energy Relaxation Time at Room Temperature in Two-Dimensional Heterostructured Semiconductors
Authors: Sužiedėlis Algirdas , Ašmontas Steponas , Gradauskas Jonas , Čerškus Aurimas , Anbinderis Maksimas
Published: April 2022

Hot carriers are a critical issue in modern photovoltaics and miniaturized electronics. We present a study of hot electron energy relaxation in different two-dimensional electron gas (2DEG) structures and compare the measured values with regard to the dimensionality of the semiconductor formations. Asymmetrically necked structures containing different types of AlGaAs/GaAs single quantum wells, GaAs/InGaAs layers, or bulk highly and lowly doped GaAs formations were investigated. The research was performed in the dark and under white light illumination at room temperature. Electron energy relaxation time was estimated using two models of I-V characteristics analysis applied to a structure with n-n+ junction and a model of voltage sensitivity dependence on microwave frequency. The best results were obtained using the latter model, showing that the electron energy relaxation time in a single quantum well structure (2DEG structure) is twice as long as that in the bulk semiconductor.
Corrosion Behavior of SiMo Cast Iron under Controlled Conditions
Authors: Stawarz Marcin , Nuckowski Paweł M.
Published: April 2022

The resistance of cast iron to chemical and electrochemical corrosion depends on the exposure conditions, chemical composition and the distribution of alloying elements in the microstructure. The article presents an attempt to describe the formation of a corrosion layer under controlled chemical corrosion conditions for SiMo ductile iron. In the experiment, a (HT-HRD) chamber for heating the samples with a controlled atmosphere was used, at the same time providing the possibility of testing the sample surface using the XRD method. The analysis was both qualitative and quantitative. It allowed us to capture the sequence of the oxide layer growth on the tested samples. The beneficial effect of molybdenum on the corrosion resistance of SiMo cast iron has been proven. For all cases under analysis, the phenomenon of an increase in the share of hematite (Fe2O3) and magnetite (Fe3O4) was observed in the subsequent sample heating cycles. It turned out that the addition of molybdenum helps to create a tight oxide coating that inhibits the further growth of corrosion processes. Increasing the share of molybdenum in the alloy also reduces the thickness of the oxide layer.
Si/SiO2/Al2O3 Supported Growth of CNT Forest for the Production of La/ZnO/CNT Photocatalyst for Hydrogen Production
Authors: Irfan Muhammad , Shukrullah Shazia , Naz Muhammad Yasin , Ahmad Irshad , Shoukat Bilal , Legutko Stanislaw , Petrů Jana , Rahman Saifur , Alsaiari Mabkhoot A.
Published: April 2022

The use of ZnO as a photocatalyst with a reduced recombination rate of charge carriers and maximum visible light harvesting remains a challenge for researchers. Herein, we designed and synthesized a unique La/ZnO/CNTs heterojunction system via a sol–gel method to evaluate its photocatalytic performance for hydrogen evolution. A ferrocene powder catalyst was tested for the production of CNT forests over Si/SiO2/Al2O3 substrate. A chemical vapor deposition (CVD) route was followed for the forest growth of CNTs. The La/ZnO/CNTs composite showed improved photocatalytic efficiency towards hydrogen evolution (184.8 mmol/h) in contrast to 10.2 mmol/h of pristine ZnO. The characterization results show that promoted photocatalytic activity over La/ZnO/NTs is attributed to the spatial separation of the charge carriers and extended optical absorption towards the visible light spectrum. The optimum photocatalyst shows a 16 h cycle performance for hydrogen evolution. The H2 evolution rate under visible light illumination reached 10.2 mmol/h, 145.9 mmol/h and 184.8 mmol/h over ZnO, La/ZnO and La/ZnO/CNTs, respectively. Among the prepared photocatalysts, ZnO showed the lowest H2 evolution rate due to the fast recombination of electron–hole pairs than heterojunction photocatalysts. This research paves the way for the development of ZnO and CNT-based photocatalysts with a wide optical response and reduced charge carrier recombinations.
Diabetes Mellitus and Dental Implants: A Systematic Review and Meta-Analysis
Authors: Al Ansari Yasmin , Shahwan Halime , Chrcanovic Bruno Ramos
Published: April 2022

The present review aimed to evaluate the impact of diabetes mellitus on dental implant failure rates and marginal bone loss (MBL). An electronic search was undertaken in three databases, plus a manual search of journals. Meta-analyses were performed as well as meta-regressions in order to verify how the odds ratio (OR) and MBL were associated with follow-up time. The review included 89 publications. Altogether, there were 5510 and 62,780 implants placed in diabetic and non-diabetic patients, respectively. Pairwise meta-analysis showed that implants in diabetic patients had a higher failure risk in comparison to non-diabetic patients (OR 1.777, p < 0.001). Implant failures were more likely to occur in type 1 diabetes patients than in type 2 (OR 4.477, p = 0.032). The difference in implant failure between the groups was statistically significant in the maxilla but not in the mandible. The MBL mean difference (MD) between the groups was 0.776 mm (p = 0.027), with an estimated increase of 0.032 mm in the MBL MD between groups for every additional month of follow-up (p < 0.001). There was an estimated decrease of 0.007 in OR for every additional month of follow-up (p = 0.048). In conclusion, implants in diabetic patients showed a 77.7% higher risk of failure than in non-diabetic patients.
Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro
Authors: Sarfraz Sonia , Mäntynen Pilvi-helinä , Laurila Marisa , Suojanen Juho , Saarnio Juha , Rossi Sami , Horelli Jani , Kaakinen Mika , Leikola Junnu , Reunanen Justus
Published: April 2022

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3× with 1× PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.
Explicit Analysis of Nonuniform Irradiation Swelling Pressure Exerting on Dispersion Fuel Matrix Based on the Equivalent Inclusion Method
Authors: Dong Yingxuan , Lv Junnan , Zuo Hong , Li Qun
Published: April 2022

Under irradiation, dispersion nuclear fuel meat consists of a three-phase composite of fuel particles surrounded by an interaction layer dispersed within a metal matrix. Nonuniform swelling pressures are exerted on the matrix, generated by irradiation swelling of the fuel particles. As these are considerable, they can cause matrix failure, but they are difficult to calculate. In this paper, taking into account thermal expansion, nonuniform fission pores and the interaction layer, nonuniform irradiation swelling pressure has been formulated, based on the equivalent inclusion method. By means of doubly equivalent transformations, a porous fuel particle, surrounded by an interaction layer, which is under irradiation, can be simplified as a homogeneous particle with the eigenstrain. With the aid of Green’s function, nonuniform irradiation swelling pressure can be numerically analyzed. The simulation results of swelling pressures are in good agreement with numerical calculations. Furthermore, several simplified examples have been given to investigate the factors of influence and the impact mechanisms. Conclusions are drawn that nonuniform irradiation swelling pressure can be analyzed numerically and adopted to explore matrix failure. It is identified that the number and locations of fission pores inside a fuel particle are key factors for nonuniformity of swelling pressures. The volatility of swelling pressures is aggravated by burnup, while the average values of swelling pressures are intensely affected by temperature. This work provides a perspective to investigate the strength and integrity of dispersion fuel meat under high burnup.
New Chemically Resistant Coating Systems with Progressive Incorporation of Hazardous Waste in Polyurethane and Epoxy Matrices
Authors: Hodul Jakub , Mészárosová Lenka , Drochytka Rostislav
Published: April 2022

New types of highly chemically resistant coating systems, primarily intended for concrete and metal substrates, were designed and experimentally verified in the paper. Secondary raw materials in optimal amounts, including solidified hazardous waste (e.g., end product and cement bypass dust), were used as microfillers. The polymer coating systems, containing pre-treated hazardous waste (HW), showed high abrasion resistance and excellent adhesion to metal and concrete surfaces. Based on polyurethane and epoxy resins, the coatings can be used in environments where aggressive chemical media act, such as sewers and the chemical industry. The developed polymeric coating systems showed even better properties than the compared reference coating systems. The chemical resistance of the three-layer coating systems was evaluated both visually and based on changes in mechanical properties, such as hardness and adhesion. The microstructure of the coating systems was also monitored using a digital optical microscope and a scanning electron microscope with energy dispersive X-ray analysis (SEM-EDX) after chemical stress. It was observed that the particles of HW were fully incorporated into the polymer matrix of the coating systems.
MulTi-FAST: A Machinability Assessment of Functionally Graded Titanium Billets Produced from Multiple Alloy Powders
Authors: Levano Blanch Oliver , Suárez Fernández Daniel , Graves Alex , Jackson Martin
Published: April 2022

Technological developments in the area of functionally graded multi-material manufacture are poised to disrupt the aerospace industry, providing the means for step-change improvements in performance through tailored component design. However, the challenges faced during the downstream processing, i.e., machining of such functionally graded multi-materials are unclear. In this study, the challenges involved when face-turning billets consisting of multiple alloys are assessed. To achieve this, a cylindrical billet consisting of Ti-64, Ti-6242, Ti-5553 and Beta C alloys was manufactured from powder feedstock using field-assisted sintering technique (FAST) and termed MulTi-FAST billets. A detailed study of the structural integrity during machining at the diffusion bond interfaces of multiple titanium alloy bond pairings in the MulTi-FAST billet was conducted. The machining forces were measured during face-turning to investigate the impact and behaviour of different alloy pairings during a continuous machining operation. The results showed the significant differences in force machining response, surface topography and the type of surface damage was dependent on the direction the titanium alloy graded pairings were machined in. In terms of subsurface microstructural damage, regardless of the machining direction, no critical damage was found in the vicinity of the bonded alloys. The findings provide an insight into the deformation characteristics and challenges faced in the machining of functionally graded components with multiple titanium alloys.
High-Entropy Borides under Extreme Environment of Pressures and Temperatures
Authors: Iwan Seth , Lin Chia-Min , Perreault Christopher , Chakrabarty Kallol , Chen Cheng-Chien , Vohra Yogesh , Hrubiak Rostislav , Shen Guoyin , Velisavljevic Nenad
Published: April 2022

The high-entropy transition metal borides containing a random distribution of five or more constituent metallic elements offer novel opportunities in designing materials that show crystalline phase stability, high strength, and thermal oxidation resistance under extreme conditions. We present a comprehensive theoretical and experimental investigation of prototypical high-entropy boride (HEB) materials such as (Hf, Mo, Nb, Ta, Ti)B2 and (Hf, Mo, Nb, Ta, Zr)B2 under extreme environments of pressures and temperatures. The theoretical tools include modeling elastic properties by special quasi-random structures that predict a bulk modulus of 288 GPa and a shear modulus of 215 GPa at ambient conditions. HEB samples were synthesized under high pressures and high temperatures and studied to 9.5 GPa and 2273 K in a large-volume pressure cell. The thermal equation of state measurement yielded a bulk modulus of 276 GPa, in excellent agreement with theory. The measured compressive yield strength by radial X-ray diffraction technique in a diamond anvil cell was 28 GPa at a pressure of 65 GPa, which is a significant fraction of the shear modulus at high pressures. The high compressive strength and phase stability of this material under high pressures and high temperatures make it an ideal candidate for application as a structural material in nuclear and aerospace fields.
Automated Development of an Accurate Diffusion Database in Fcc AlCoCrFeNi High-Entropy Alloys from a Big Dataset of Composition Profiles
Authors: Zhong Jing , Li Qin , Deng Chunming , Zhang Lijun
Published: April 2022

This study aims to incorporate a big dataset of composition profiles of fcc AlCoCrFeNi alloys, in addition to those of the related subsystem, to develop a self-consistent kinetic description for quinary high-entropy alloys. The latest feature of the HitDIC (High-throughput Determination of Interdiffusion Coefficients) code was adopted in a high-throughput and automatic manner for accommodating a dataset of composition profiles with up to 87 diffusion couples. A good convergence for the optimization process was achieved, while satisfactory results regarding the composition profiles and previously evaluated diffusion properties were obtained. Here, we present an investigation into the elemental effect of Al towards interdiffusion and tracer diffusion, and their potential effect on creep and precipitation processes.
Prediction of Ultrasonic Pulse Velocity for Cement, Mortar, and Concrete through a Multiscale Homogenization Approach
Authors: Jiang Jingluo , Zhang Dawei , Gong Fuyuan , Zhi Dian
Published: April 2022

Ultrasonic testing (UT) is an important method for concrete, and ultrasonic pulse velocity is commonly used to evaluate the quality of concrete materials in existing studies. The ultrasonic pulse velocity of concrete materials is affected by many factors; therefore, it is necessary to establish a quantitative prediction model for the ultrasonic pulse velocity of concrete materials. Based on the multiscale homogenization method, concrete material is divided into different scales of homogenized materials, namely cement paste, mortar, and concrete. Then, a multiscale ultrasonic pulse velocity model is established through a combination of elasticity formulation and the hydration model. At the three scales of cement paste, mortar, and concrete, the elastic parameters and ultrasonic pulse velocity were predicted with the water-to-cement ratio of 0.35, 0.5, and 0.65, respectively. The ultrasonic pulse velocity of concrete with different water-to-cement ratios and different ages were measured in the test and predicted by the model. The results show that the predicted value of ultrasonic pulse velocity is within the error range of ±1.5% of the measured ultrasonic pulse velocity, suggesting that the established prediction model of ultrasonic pulse velocity can reliably predict the velocity change in concrete materials.
Numerical Prediction of Strength of Socket Welded Pipes Taking into Account Computer Simulated Welding Stresses and Deformations
Authors: Domański Tomasz , Piekarska Wiesława , Saternus Zbigniew , Kubiak Marcin , Stano Sebastian
Published: April 2022

The paper presents a numerical model based on the finite element method (FEM) to predict deformations and residual stresses in socket welding of different diameter stainless steel pipes made of X5CrNi18-10 steel. The next part of the paper concerns the determination of strength properties of a welded joint in terms of a shear test. A thermo-elastic–plastic numerical model is developed using Abaqus FEA software in order to determine the thermal and mechanical phenomena of the welded joint. This approach requires the implementation of moveable heat source power intensity distribution based on circumferentially moving Goldak’s heat source model. This model is implemented in the additional DFLUX subroutine, written in Fortran programming language. The correctness of the assumed model of thermal phenomena is confirmed by examinations of the shape and size of the melted zone. The strength of the welded joint subjected to shear is verified by performing a compression test of welded pipes as well as computer simulations with validation of the computational model using the Dantec 3D image correlation system.
Fatigue Fracture Analysis on 2524 Aluminum Alloy with the Influence of Creep-Aging Forming Processes
Authors: Ma Liyong , Liu Chi , Ma Minglei , Wang Zhanying , Wu Donghao , Liu Lijuan , Song Mingxing
Published: April 2022

The different creep-aging forming processes of 2524 aluminum alloy were taken as the research object, and the effects of creep-aging temperature and creep stress on the fatigue-crack propagation properties of the alloy were studied. The research results showed the following under the same sintering time of 9 h, at creep-aging temperatures of 100 °C, 130 °C, 160 °C, and 180 °C, respectively, with an increase in creep-aging temperature: the fatigue-crack propagation rate was promoted, the spacing of fatigue striations increased, and the sizes of dimples decreased while the number was enlarged; this proves that the fatigue property of the alloy was weakened. Compared with the specimens with creep deformation radii of 1000 mm and 1500 mm, the creep deformation stress was the smallest when the forming radius was 1800 mm, with a higher threshold value of fatigue-crack growth in the near-threshold region of fatigue-crack propagation (ΔK ≤ 8 MPa·m1/2). Under the same fatigue cycle, the specimens under the action of larger creep stress endured a longer fatigue stable-propagation time and a faster fracture speed. Comparing the effect of creep-aging temperature and creep stress, the creep-aging temperature plays a dominant role in the fatigue-crack propagation of creep-aged 2524 aluminum alloy.
Obtaining and Characterization of Highly Crystalline Recycled Graphites from Different Types of Spent Batteries
Authors: Alcaraz Lorena , Díaz-Guerra Carlos , Calbet Joaquín , López María Luisa , López Félix A.
Published: April 2022

Spent batteries recycling is an important way to obtain low-cost graphite. Nevertheless, the obtaining of crystalline graphite with a rather low density of defects is required for many applications. In the present work, high-quality graphites have been obtained from different kinds of spent batteries. Black masses from spent alkaline batteries (batteries black masses, BBM), and lithium-ion batteries from smartphones (smartphone black masses, SBM) and electric and/or hybrid vehicles (lithium-ion black masses, LBM) were used as starting materials. A hydrometallurgical process was then used to obtain recycled graphites by acidic leaching. Different leaching conditions were used depending on the type of the initial black mass. The final solids were characterized by a wide set of complementary techniques. The performance as Li ion batteries anode of the sample with better structural quality was assessed.
Pregnancy Outcomes in a Cohort of Patients Who Underwent Double-J Ureteric Stenting—A Single Center Experience
Authors: Radu Viorel Dragos , Vasilache Ingrid-Andrada , Costache Radu-Cristian , Scripcariu Ioana-Sadiye , Nemescu Dragos , Carauleanu Alexandru , Nechifor Valentin , Groza Veaceslav , Onofrei Pavel , Boiculese Lucian , Socolov Demetra
Published: April 2022

Background and Objectives: Minimally invasive procedures, such as double-J ureteric stenting, could be a promising therapeutic alternative to conservative management of obstructive urinary tract pathology. We aimed to evaluate the safety and effectiveness of double-J ureteric stenting in pregnant women with ureterohydronephrosis or urolithiasis, along with their infectious complications, and to assess the pregnancy outcomes of this cohort of patients in comparison with a control group. Materials and Methods: This observational retrospective study included 52 pregnant patients who underwent double-J ureteric stenting for urologic disorders in the Urology Department of ‘C.I. Parhon’ University Hospital, and who were followed up at a tertiary maternity hospital- ‘Cuza-Voda’, Iasi, Romania. The control group (63 patients) was randomly selected from the patient’s cohort who gave birth in the same time frame at the maternity hospital, without urinary pathology. Clinical, sonographic, and laboratory variables were examined. Descriptive statistics, non-parametric tests, and a one-to-one propensity score-matched analysis were used to analyze our data. Results: The univariate analysis indicated a significant statistical difference between the control group and the interventional group regarding maternal age (p = 0.018), previous maternal history of renal colic (p = 0.005) or nephrolithiasis (p = 0.002). After applying the propensity score-matched analysis, cesarean delivery rates (p < 0.001), preterm labour (p = 0.039), premature rupture of membranes (p = 0.026), preterm birth rates (p = 0.002), and post-partum UTI rates (p = 0.012) were significantly different between the control group and the matched treatment group. Ureterohydronephrosis, whether simple (n = 37; 71.2%) or infected (n = 13; 25%), was the main indication for double-J ureteric stenting. Complications such as pain (n = 21; 40.3%), stent migration (n = 3; 5.76%) or encrustation (n = 2; 3.84%), as well as reflux pyelonephritis (n = 2; 3.84%) and gross hematuria (n = 1; 1.92%) were recorded during follow-up. Conclusions: Our results show that double-J stenting is a safe and effective treatment option for pregnant patients with obstructive urological disorders.
Isolated Proximal Median Neuropathy after Aortic Dissection Repair: Case Report
Authors: Chen Yen-Yu , Huang Chao-Chun , Wang Jia-Chi , Hsu Po-Cheng
Published: April 2022

Surgery-related isolated proximal median neuropathy is a rare complication. Brachial plexus injury is a possible complication after major cardiac surgery; however, isolated mononeuropathy is less frequently documented. We present an unusual case of isolated proximal median neuropathy after aortic dissection repair surgery in a 39-year-old man. Electrodiagnostic study and ultrasound examinations helped in localizing the lesion to the axillary region. Serial follow-ups showed improvement in electrodiagnostic parameters, which were compatible with clinical symptoms. Partial recovery was achieved at the seventh month follow-up. This case report aimed to increase awareness of nerve stretching during open heart surgery and demonstrate the diagnosis and clinical follow-up by concomitant use of electrodiagnostic and nerve ultrasound studies.
Plasma Concentrations of Cytokines in Patients with Combined Hyperlipidemia and Atherosclerotic Plaque before Treatment Initiation—A Pilot Study
Authors: Basiak Marcin , Kosowski Michal , Hachula Marcin , Okopien Boguslaw
Published: April 2022

Background and Objectives: The formation and destabilization of atherosclerotic plaques is a complex process involving several proteins and cytokines. Interleukin 6 (IL-6), interleukin 18 (IL-18), and tumor necrosis factor (TNF-α) are examples of such cytokines. The goal of our research is to compare the concentrations of the above-mentioned indicators in the plasma of patients with verified high-risk atherosclerotic plaque to the plasma levels of healthy people before lipid lowering therapy. Materials and Methods: Patients with dyslipidemia who had the presence of unstable atherosclerotic plaque verified by ultrasonography were included in the study. The concentrations of IL-6, IL-18 and TNF-α in the plasma of these people were determined and compared with the concentrations of these cytokines in the plasma of the control group. Results: Levels of lipid panel, IL-6 and IL-18 were significantly lower in the group of healthy people than in the study group. Conclusions: The concentrations of IL-6 and IL-18 in the plasma of patients with ruptured plaque are higher than in the plasma of healthy people, suggesting that these cytokines as a panel might be used as new indicators of the presence of unstable atherosclerotic plaque.
Air-to-Air Heat and Moisture Recovery in a Plate-Frame Exchanger Using Composite and Asymmetric Membranes
Authors: Jahed Mogharrab Amir , Sharifian Seyedmehdi , Asasian-Kolur Neda , Ghadimi Ali , Haddadi Bahram , Harasek Michael
Published: April 2022

The present work studied an air-to-air exchanger comprising a flat plate module with a diagonal channel and a counterflow configuration for the air streams. The objective of this study was to remove moisture and sensible heat from an exhaust air stream by indirect contact with another air stream. The temperature and flow rate of the exhaust air was in the range of 40–80 °C and 1–5 L·min−1, respectively, and the fresh ambient air to exhaust air flow ratio was 1–5. An asymmetric porous membrane (P-MEM), a thin film composite membrane (C-MEM), and a kraft paper were used as the core for the heat exchange module. The most influential parameter was the humid air temperature, with a direct positive effect (50–60%) due to the increase in the kinetic energy of the water molecules. The other effective parameter was the flow rate of the humid gas with a reverse effect on the enthalpy exchanger performance (25–37%). The ratio of “fresh” air to “exhaust” air had the lowest positive effect (8–10%) on the total effectiveness. The sensible effectiveness of different membranes under the studied conditions was relatively the same, showing their similar heat conductivity. However, the kraft paper showed the best performance compared to the synthetic membranes due to having a porous/hydrophile texture. P-MEM with an asymmetric porous texture showed the closest performance to kraft paper. Furthermore, it was found that under limited conditions, such as higher temperatures (70 and 80 °C) and flow rates (5 L·min−1) for the humid air, the performance of P-MEM was a little better than the kraft paper. However, C-MEM with the lowest total effectiveness and overall heat transfer coefficient (150–210 W·m−2·K−1) showed that the hydrophile PEBAX layer could not contribute to moisture recovery due to its high thickness.
Dynamic Interaction between Dislocation and Irradiation-Induced Defects in Stainless Steels during Tensile Deformation
Authors: Fukumoto Ken-ichi , Umehara Kohei , Yabuuchi Kiyohiro
Published: April 2022

A series of in-situ transmission electron microscopy (TEM) observations during tensile deformation were conducted on the ion-irradiated stainless steel. The jerky motion of dislocations appeared, and dislocations were pinned and depinned at the defects through the in-situ TEM observation. The jump distance traveled by dislocation was measured and discussed as the mean interval of defects interacting with the dislocation motion. Microstructural information of irradiation defects such as obstacle interval was obtained by TEM and atom probe tomography (APT), and the type of pinning site was identified. It was found that Frank loops and black dots were irradiation defects that strongly interacted with dislocations. It was suggested that solute atom clusters act as weak obstacles for dislocations in the dynamic interaction behavior with dislocation motion.
Green Synthesis of Silver Oxide Nanoparticles for Photocatalytic Environmental Remediation and Biomedical Applications
Authors: Danish Mir Sayed Shah , Estrella-Pajulas Liezel L. , Alemaida Ivy Michelle , Grilli Maria Luisa , Mikhaylov Alexey , Senjyu Tomonobu
Published: April 2022

Among the most notable nanotechnology applications is its employment in environmental remediation and biomedical applications. Nonetheless, there is a need for cleaner and sustainable methods in preparing nanomaterials that use cheaper, more environment-friendly precursors than the conventional synthesis process. The green chemistry approach for the preparation of nanoparticles is becoming more attractive as it uses non-toxic chemicals and reagents. It also offers cost-effective synthesis process as it uses readily available plant sources and microbe as redox mediators in converting metallic cations to metal or metal oxide nanoparticles. The extracts of these plants and microbe sources contain phytochemicals and metabolites in variable quantities, which serve as redox mediators and capping agents that stabilize the biosynthesized nanoparticles. The present article reviews the recent studies on the fabrication of silver oxide nanoparticles (Ag2O-NPs) via plant-mediated and microbe-mediated green synthesis, giving a concise discussion on the green preparation of Ag2O-NPs employing extracts of different plants and microbial sources. The performances of the biosynthesized Ag2O-NPs are also reviewed, highlighting their potential use in photocatalysis and biomedical applications.
Differential Accumulation of Metabolites and Transcripts Related to Flavonoid, Styrylpyrone, and Galactolipid Biosynthesis in Equisetum Species and Tissue Types
Authors: Parrish Amber N. , Lange Iris , Šamec Dunja , Lange Bernd Markus
Published: April 2022

Three species of the genus Equisetum (E. arvense, E. hyemale, and E. telmateia) were selected for an analysis of chemical diversity in an ancient land plant lineage. Principal component analysis of metabolomics data obtained with above-ground shoot and below-ground rhizome extracts enabled a separation of all sample types, indicating species- and organ-specific patterns of metabolite accumulation. Follow-up efforts indicated that galactolipids, carotenoids, and flavonoid glycosides contributed positively to the separation of shoot samples, while stryrylpyrone glycosides and phenolic glycosides were the most prominent positive contributors to the separation of rhizome samples. Consistent with metabolite data, genes coding for enzymes of flavonoid and galactolipid biosynthesis were found to be expressed at elevated levels in shoot samples, whereas a putative styrylpyrone synthase gene was expressed preferentially in rhizomes. The current study builds a foundation for future endeavors to further interrogate the organ and tissue specificity of metabolism in the last living genus of a fern family that was prevalent in the forests of the late Paleozoic era.
Identification of Preisach Model Parameters Based on an Improved Particle Swarm Optimization Method for Piezoelectric Actuators in Micro-Manufacturing Stages
Authors: Yang Lei , Ding Bingxiao , Liao Wenhu , Li Yangmin
Published: April 2022

The Preisach model is a typical scalar mathematical model used to describe the hysteresis phenomena, and it attracts considerable attention. However, parameter identification for the Preisach model remains a challenging issue. In this paper, an improved particle swarm optimization (IPSO) method is proposed to identify Preisach model parameters. Firstly, the Preisach model is established by introducing a Gaussian−Gaussian distribution function to replace density function. Secondly, the IPSO algorithm is adopted to Fimplement the parameter identification. Finally, the model parameter identification results are compared with the hysteresis loop of the piezoelectric actuator. Compared with the traditional Particle Swarm Optimization (PSO) algorithm, the IPSO algorithm demonstrates faster convergence, less calculation time and higher calculation accuracy. This proposed method provides an efficient approach to model and identify the Preisach hysteresis of piezoelectric actuators.
Optimization AlGaN/GaN HEMT with Field Plate Structures
Authors: Shi Ningping , Wang Kejia , Zhou Bing , Weng Jiafu , Cheng Zhiyuan
Published: April 2022

AlGaN/GaN HEMTs with several different designs of field plate structure are studied for device optimization purposes. To increase device breakdown voltage, optimal dimensions of field plates were first investigated using Silvaco TCAD software, and the electrical characteristics of the devices are analyzed. Several devices were designed and fabricated based on the simulation results. It has been confirmed that the gate-source composite field plate (SG-FP) has a higher breakdown voltage than other types of field plate structures, with FOM reaches 504 MW/cm−2, showing that the device with SG-FP structure outperforms the other three structures. The experiment and simulation verify that the gate-source composite field plate optimizes FOM by increasing the breakdown voltage and reducing the intrinsic on-resistance so that the device has better electrical performance and a wider application range.
Simulation Design of Surface Acoustic Wave Sensor Based on Langasite Coplanar Integration with Multiple Parameters
Authors: Liang Xiaorui , Zhang Yongwei , Xu Fangmeng , Tan Qiulin , Zhang Juan
Published: April 2022

In the harsh environment of high temperature and high rotation, a single parameter is difficult to satisfy the multi-parameter test requirements of aerospace metallurgy. Therefore, a multi-parameter coplanar integrated surface acoustic wave (SAW) sensor based on Langasite (LGS) is proposed. In this paper, the optimal cut for different measurement parameters is analyzed, and the optimal cut to temperature, pressure and vibration are obtained. The simulation results show that (0°, 138.5°, 25°) LGS has superior second-order temperature sensitivity, the edge of the rectangular sealed cavity is more suitable for pressure sensors, and the optimal cut is (0°, 138.5°, 30°). The stress of the vibration sensor cantilever beam is mainly concentrated on the edge of the fixed end, and the optimal cut is (0°, 138.5°, 35°). Based on the optimal sensitive tangential direction of each sensitive element and the symmetry of the Langasite wafer, the reasonable layout of the coplanar integrated structure with the three parameters of temperature, pressure and vibration is determined. Moreover, according to the optimal orientation selection and reasonable structure layout of each parameter, combined with frequency separation rules, the parameters of interdigital electrode were determined, and the idea of multi-parameter integrated design was simulated and verified.