bluuebunny/crossref_metadata_2025 huggingface dataset:
Co-Bonded Hybrid Thermoplastic-Thermoset Composite Interphase: Process-Microstructure-Property Correlation
Authors: Zanjani Jamal Seyyed Monfared , Baran Ismet
Published: January 2021

Co-bonding is an effective joining method for fiber-reinforced composites in which a prefabricated part bonds with a thermoset resin during the curing process. Manufacturing of co-bonded thermoset-thermoplastic hybrid composites is a challenging task due to the complexities of the interdiffusion of reactive thermoset resin and thermoplastic polymer at the interface between two plies. Herein, the interphase properties of co-bonded acrylonitrile butadiene styrene thermoplastic to unsaturated polyester thermoset are investigated for different processing conditions. The effect of processing temperature on the cure kinetics and interdiffusion kinetics are studied experimentally. The interphase thickness and microstructure are linked to the chemo-rheological properties of the materials. The interdiffusion mechanisms are explored and models are developed to predict the interphase thickness and microstructure for various process conditions. The temperature-dependent diffusivities were estimated by incorporating an inverse diffusion model. The mechanical response of interphases was analyzed by the Vickers microhardness test and was correlated to the processing condition and microstructure. It was observed that processing temperature has significant effect on the interdiffusion process and, consequently, on the interphase thickness, its microstructure and mechanical performance.
Synergistic Effect of F–T Synthetic Wax and Surface-Active Agent Content on the Properties and Foaming Characteristics of Bitumen 50/70
Authors: Iwański Mateusz M
Published: January 2021

The level of the properties of bituminous mixtures produced with water foamed bitumen relies on the optimum characteristics of the bitumen. One way to achieve the desired characteristics is to modify the bitumen with chemical additives before it is foamed. Bitumen 50/70 treated with a surface-active agent (SAA) at 0.2%, 0.4% and 0.6% and Fischer–Tropsch (F–T) synthetic wax at 1.5%, 2.0%, 2.5% and 3.0% was used in the tests. The effect of the modifiers was investigated by assessing bitumen properties (penetration, softening point, Fraass breaking point and dynamic viscosity at 60 °C, 90 °C and 135 °C) and foam parameters (maximum expansion—ER, half-life—HL). For statistical evaluation of the test results, models of the properties of bitumen 50/70 were developed as a function of the contents of F–T synthetic wax and SAA. It was found that 2.0% F–T wax and 0.6% SAA were optimum contents for achieving the desired standard properties and foam characteristics of the tested binder. The developed models allow determining the composition of the modified binder depending on the required foam characteristics for specific applications in road construction. The recommended composition of the chemical additives used to modify the binder was also established to ensure its optimum properties.
Effects of Boron Carbide on Coking Behavior and Chemical Structure of High Volatile Coking Coal during Carbonization
Authors: Wu Qiang , Sun Can , Zhu Zi-Zong , Wang Ying-Dong , Zhang Chong-Yuan
Published: January 2021

Modified cokes with improved resistance to CO2 reaction were produced from a high volatile coking coal (HVC) and different concentrations of boron carbide (B4C) in a laboratory scale coking furnace. This paper focuses on modification mechanism about the influence of B4C on coking behavior and chemical structure during HVC carbonization. The former was studied by using a thermo-gravimetric analyzer. For the latter, four semi-cokes prepared from carbonization tests for HVC with or without B4C at 450 °C and 750 °C, respectively, were analyzed by using Fourier transform infrared spectrum and high-resolution transmission electron microscopy technologies. It was found that B4C will retard extensive condensation and crosslinking reactions by reducing the amount of active oxygen obtained from thermally produced free radicals and increase secondary cracking reactions, resulting in increasing size of aromatic layer and anisotropic degree in coke structure, which eventually improves the coke quality.
Hot Deformation and Dynamic Recrystallisation Behaviour of Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Magnesium Alloy
Authors: Ullmann Madlen , Kittner Kristina , Prahl Ulrich
Published: January 2021

In this work, the deformation behaviour of a twin-roll cast (TRC) Mg-6.8Y-2.5Zn-0.4Zr alloy during plane strain compression was characterised by high-temperature testing. Based on the experimental data, the values of strain-rate sensitivity, the efficiency of power dissipation and the instability parameter were investigated under the conditions of various hot deformation parameters. In contrast to conventionally cast material, no lamellae of the LPSO (long period stacking ordered) phase were precipitated in the magnesium matrix after TRC. The precipitation of fine lamellar LPSO phases only occurred during cooling to forming temperature after the heat treatment. Dynamic recrystallization (DRX) hardly occurred during deformation at temperatures between 350 °C and 400 °C. This can be attributed to the precipitation of the lamellar LSPO phases, which contribute to retardation of the DRX process. At higher deformation temperatures and strain rates DRX is pronounced and the twin-induced (TRDX) as well as continuous dynamic recrystallization could be identified as the dominant softening mechanisms. The processing maps were established by superimposing the instability map over the power dissipation map, this being associated with microstructural evolution analysis in the hot deformation processes. Two instability zones could be recognised for the twin-roll cast and heat-treated Mg-6.8Y-2.5Zn-0.4Zr alloy: (1) 350 °C to 460 °C and 0.01 s−1 to 0.3 s−1 and (2) 485 °C to 525 °C and 2.5 s−1 to 10 s−1, where deformation is not favourable.
Microstructure, Mechanical Properties, and Corrosion Behavior of Ultra-Low Carbon Bainite Steel with Different Niobium Content
Authors: Zong Yun , Liu Chun-Ming
Published: January 2021

Four types of ultra-low carbon bainite (ULCB) steels were obtained using unified production methods to investigate solely the effect of niobium content on the performance of ULCB steels. Tensile testing, low-temperature impact toughness testing, corrosion weight-loss method, polarization curves, electrochemical impedance spectroscopy (EIS), and the corresponding organizational observations were realized. The results indicate that the microstructure of the four steels comprise granular bainite and quite a few martensite/austenite (M/A) elements. The niobium content affects bainite morphology and the size, quantity, and distribution of M/A elements. The elongation, yield strength, and tensile strength of the four types of ULCB steels are above 20%, 500 MPa, and 650 MPa, respectively. The impact toughness of the four types of ULCB steels at −40 °C is lower than 10 J. Steel with Nb content of 0.0692% has better comprehensive property, and maximum charge transfer resistance in 3.5 wt.% NaCl solution at the initial corrosion stage. The corrosion products on the surface of steel with higher niobium content are much smoother and denser than those steel with lower niobium content after 240 h of corrosion. The degree of corrosion decreases gradually with the increase of niobium content at the later stage of corrosion.
The Effect of Electrophoretic Deposition Parameters on the Microstructure and Adhesion of Zein Coatings to Titanium Substrates
Authors: Maciąg Filip , Moskalewicz Tomasz , Kowalski Kazimierz , Łukaszczyk Alicja , Hadzhieva Zoya , Boccaccini Aldo Roberto
Published: January 2021

Zein coatings were obtained by electrophoretic deposition (EPD) on commercially pure titanium substrates in an as-received state and after various chemical treatments. The properties of the zein solution, zeta potential and conductivity, at varying pH values were investigated. It was found that the zein content and the ratio of water to ethanol of the solution used for EPD, as well as the process voltage value and time, significantly influence the morphology of coatings. The deposits obtained from the solution containing 150 g/L and 200 g/L of zein and 10 vol % of water and 90 vol % of ethanol, about 4–5 μm thick, were dense and homogeneous. The effect of chemical treatment of the Ti substrate surface prior to EPD on coating adhesion to the substrate was determined. The coatings showed the highest adhesion to the as-received and anodized substrates due to the presence of a thick TiO2 layer on their surfaces and the presence of specific surface features. Coated titanium substrates showed slightly lower electrochemical corrosion resistance than the uncoated one in Ringer’s solution. The coatings showed a well-developed surface topography compared to the as-received substrate, and they demonstrated hydrophilic nature. The present results provide new insights for the further development of zein-based composite coatings for biomedical engineering applications.
Properties and Classification of Diamond-Like Carbon Films
Authors: Ohtake Naoto , Hiratsuka Masanori , Kanda Kazuhiro , Akasaka Hiroki , Tsujioka Masanori , Hirakuri Kenji , Hirata Atsushi , Ohana Tsuguyori , Inaba Hiroshi , Kano Makoto , Saitoh Hidetoshi
Published: January 2021

Diamond-like carbon (DLC) films have been extensively applied in industries owing to their excellent characteristics such as high hardness. In particular, there is a growing demand for their use as protective films for mechanical parts owing to their excellent wear resistance and low friction coefficient. DLC films have been deposited by various methods and many deviate from the DLC regions present in the ternary diagrams proposed for sp3 covalent carbon, sp2 covalent carbon, and hydrogen. Consequently, redefining the DLC region on ternary diagrams using DLC coatings for mechanical and electrical components is urgently required. Therefore, we investigate the sp3 ratio, hydrogen content, and other properties of 74 types of amorphous carbon films and present the classification of amorphous carbon films, including DLC. We measured the sp3 ratios and hydrogen content using near-edge X-ray absorption fine structure and Rutherford backscattering-elastic recoil detection analysis under unified conditions. Amorphous carbon films were widely found with nonuniform distribution. The number of carbon atoms in the sp3 covalent carbon without bonding with hydrogen and the logarithm of the hydrogen content were inversely proportional. Further, we elucidated the DLC regions on the ternary diagram, classified the amorphous carbon films, and summarized the characteristics and applications of each type of DLC.
Printable Gel Polymer Electrolytes for Solid-State Printed Supercapacitors
Authors: Seol Myeong-Lok , Nam Inho , Sadatian Ellie , Dutta Nabanita , Han Jin-Woo , Meyyappan M.
Published: January 2021

Supercapacitors prepared by printing allow a simple manufacturing process, easy customization, high material efficiency and wide substrate compatibility. While printable active layers have been widely studied, printable electrolytes have not been thoroughly investigated despite their importance. A printable electrolyte should not only have high ionic conductivity, but also proper viscosity, small particle size and chemical stability. Here, gel-polymer electrolytes (GPE) that are compatible with printing were developed and their electrochemical performance was analyzed. Five GPE formulations based on various polymer-conductive substance combinations were investigated. Among them, GPE made of polyvinylidene difluoride (PVDF) polymer matrix and LiClO4 conductive substance exhibited the best electrochemical performance, with a gravimetric capacitance of 176.4 F/g and areal capacitance of 152.7 mF/cm2 at a potential scan rate of 10 mV/s. The in-depth study of the in-plane solid-state supercapacitors based on various printed GPEs suggests that printable electrolytes provide desirable attributes for high-performance printed energy devices such as supercapacitors, batteries, fuel cells and dye-sensitized solar cells.
Nitrogen-Doped Hierarchical Porous Activated Carbon Derived from Paddy for High-Performance Supercapacitors
Authors: Yuan Yudan , Sun Yi , Feng Zhichen , Li Xingjian , Yi Ruowei , Sun Wei , Zhao Cezhou , Yang Li
Published: January 2021

A facile and environmentally friendly fabrication is proposed to prepare nitrogen-doped hierarchical porous activated carbon via normal-pressure popping, one-pot activation and nitrogen-doping process. The method adopts paddy as carbon precursor, KHCO3 and dicyandiamide as the safe activating agent and nitrogen dopant. The as-prepared activated carbon presents a large specific surface area of 3025 m2·g−1 resulting from the synergistic effect of KHCO3 and dicyandiamide. As an electrode material, it shows a maximum specific capacitance of 417 F·g−1 at a current density of 1 A·g−1 and very good rate performance. Furthermore, the assembled symmetric supercapacitor presents a large specific capacitance of 314.6 F·g−1 and a high energy density of 15.7 Wh·Kg−1 at 1 A·g−1, maintaining 14.4 Wh·Kg−1 even at 20 A·g−1 with the energy density retention of 91.7%. This research demonstrates that nitrogen-doped hierarchical porous activated carbon derived from paddy has a significant potential for developing a high-performance renewable supercapacitor and provides a new route for economical and large-scale production in supercapacitor application.
Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction
Authors: Manzhos Roman A. , Baskakov Sergey A. , Kabachkov Evgeny N. , Korepanov Vitaly I. , Dremova Nadezhda N. , Baskakova Yulia V. , Krivenko Alexander G. , Shulga Yury M. , Gutsev Gennady L.
Published: January 2021

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm3 was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction. The rGOA-MS composite material was characterized by elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. It was found that nitrogen in the material is presented by different types with the maximum concentration of pyrrole-like nitrogen. By using Raman scattering it was established that the rGOA component of the material is graphene-like carbon with an average size of the sp2-domains of 5.7 nm. This explains a quite high conductivity of the composite obtained.
Utilization of Treated Agricultural Residue Ash as Sodium Silicate in Alkali Activated Slag Systems
Authors: Ataie Feraidon F.
Published: January 2021

This study investigated the influence of rice straw ash (RSA), rice husk ash (RHA), and silica fume (SF) on alkali activated slag (AAS) systems. RSA, RHA, and SF were treated with sodium hydroxide to improve their reactivity in AAS systems. Although addition of SF in AAS systems increased compressive strength, samples containing RSA or RHA had higher compressive strength than those having SF. Treated RSA or RHA further increased compressive strength of AAS samples. It was shown that samples containing treated ash samples had similar compressive strength to those made with sodium silica activator. Therefore, it is suggested that treated ash samples could be used as alternative sources of silica for AAS. Drying shrinkage of AAS samples increased considerably when treated RSA or RHA were used as partial replacement of slag. This could be attributed to higher silica modulus (SiO2/Na2O) ratio of samples containing treated ash, which in turn would lead to a finer pore size structure compared to control samples. However, SF significantly reduced drying shrinkage of AAS. This could be because SF reduces the permeability and porosity of AAS samples.
Effect of Substrate Plate Heating on the Microstructure and Properties of Selective Laser Melted Al-20Si-5Fe-3Cu-1Mg Alloy
Authors: Ma Pan , Ji Pengcheng , Jia Yandong , Shi Xuerong , Yu Zhishui , Prashanth Konda Gokuldoss
Published: January 2021

The Al-20Si-5Fe-3Cu-1Mg alloy was fabricated using selective laser melting (SLM). The microstructure and properties of the as-prepared SLM, post-treated SLM, and SLM with substrate plate heating are studied. The as-prepared SLM sample shows a non-uniform microstructure with four different phases: fcc-αAl, eutectic Al-Si, Al2MgSi, and δ-Al4FeSi2. With thermal treatment, the phases become coarser and the δ-Al4FeSi2 phase transforms partially to β-Al5FeSi. The sample produced with SLM substrate plate heating shows a relatively uniform microstructure without a distinct difference between hatch overlaps and track cores. Room temperature compression test results show that an as-prepared SLM sample reaches a maximum strength (862 MPa) compared to the heat-treated (524 MPa) and substrate plate heated samples (474 MPa) due to the presence of fine microstructure and the internal stresses. The reduction in strength of the sample produced with substrate plate heating is due to the coarsening of the microstructure, but the plastic deformation shows an improvement (20%). The present observations suggest that substrate plate heating can be effectively employed not only to minimize the internal stresses (by impacting the cooling rate of the process) but can also be used to modulate the mechanical properties in a controlled fashion.
Effect of Pore Structure on Thermal Conductivity and Mechanical Properties of Autoclaved Aerated Concrete
Authors: Chen Gonglian , Li Fenglan , Jing Pengfei , Geng Jingya , Si Zhengkai
Published: January 2021

With the premise of investigating mechanical properties, the thermal conductivity of autoclaved aerated concrete (AAC) is a key index of self-insulation block walls for building energy conservation. This study focused on the effect of pore structures on the mechanical performance and thermal conductivity of AAC with the comparison of AAC base materials. Different kinds of AAC and their base materials were prepared and experimentally investigated. While maintaining a consistent mix proportion of the AAC base material, the pore structure of AAC was changed by the dosage of aluminum power/paste, foam stabilizer, and varying the stirring time of aluminum paste. The steam curing systems of AAC and the base material were determined based on SEM (Scanning Electronic Microscopy) and XRD (X-ray Diffraction) tests. With almost the same apparent density, the pore size decreased with the increasing content of foam stabilizer, and the mixing time of aluminum paste and foam stabilizer has a great influence on pore size. The thermal conductivity test and compressive test results indicated that that pore size had an effect on the thermal conductivity, but it had little effect on the compressive strength, and the thermal conductivity of sand aeration AAC was 8.3% higher than that of fly ash aeration AAC; the compressive strength was 10.4% higher, too. With almost the same apparent density, the regression mathematical model indicates that the thermal conductivity of AAC increased gradually with the increase of pore size, but it had little effect on the compressive strength. From the test results of basic mechanical properties, the mechanical model of cubic compressive strength, elastic modulus, axial compressive strength, and splitting tensile strength was obtained. The proposed stress–strain relationship model could well describe the relationship of AAC and the base material at the rising section of the curve.
How to Influence the Results of MCDM?—Evidence of the Impact of Cognitive Biases
Authors: Melnik-Leroy Gerda Ana , Dzemyda Gintautas
Published: January 2021

Multi-criteria decision-making (MCDM) methods aim at dealing with certain limitations of human information processing. However, cognitive biases, which are discrepancies of human behavior from the behavior of perfectly rational agents, might persist even when MCDM methods are used. In this article, we focus on two among the most common biases—framing and loss aversion. We test whether these cognitive biases can influence in a predictable way both the criteria weights elicited using the Analytic Hierarchy Process (AHP) and the final ranking of alternatives obtained with the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). In a controlled experiment we presented two groups of participants with a multi-criteria problem and found that people make different decisions when presented with different but objectively equivalent descriptions (i.e., frames) of the same criteria. Specifically, the results show that framing and loss aversion influenced the responses of decision makers during pairwise comparisons, which in turn caused the rank reversal of criteria weights across groups and resulted in the choice of a different best alternative. We discuss our findings in light of Prospect Theory and show that the particular framing of criteria can influence the outcomes of MCDM in a predictable way. We outline implications for MCDM methodology and highlight possible debiasing techniques.
On the Effectiveness of the Digital Legal Proceedings Model in Russia
Authors: Anatoly Tikhanovich Karasev , Alexander Vladimirovich Savoskin , Veronika Aleksandrovna Meshcheryagina
Published: January 2021

Within the framework of this research, on the basis of the dialectical unity of its legal and mathematical components, on the basis of general scientific (analysis, synthesis, deduction and induction, abstraction, structural and functional method) and special research methods (formal-legal, method of legal construction, formal-logical, system, technical-legal analysis, statistical method, methods of mathematical statistics and probability theory, etc.), a model of digital legal proceedings in Russia is proposed. The article explains the optimal variant between the components of the digital legal proceedings model in Russia, as well as providing an analysis and evaluation of the effectiveness of the digital legal proceedings model and the prospects for the development of digital legal proceedings. It is concluded that there is a need to develop legal regulation in terms of introducing the definition of “electronic evidence”, types of electronic evidence; it is recognized as a positive practice of implementing a video-conferencing system that ensures the implementation of citizens’ rights to participate in a court session, which significantly reduces the time for case consideration; the need to create a single Internet portal for receiving, processing, and providing electronic documents by all authorities in Russia is explained. In this research, it is explained that the use of mathematical algorithms in evaluating evidence and modeling the behavior of participants in trials is now at an early stage of development, which allows them to be used only in the consideration of similar cases.
On the Existence of a Unique Solution for a Class of Fractional Differential Inclusions in a Hilbert Space
Authors: Kamenskii Mikhail , Obukhovskii Valeri , Petrosyan Garik , Yao Jen-Chih
Published: January 2021

We obtained results on the existence and uniqueness of a mild solution for a fractional-order semi-linear differential inclusion in a Hilbert space whose right-hand side contains an unbounded linear monotone operator and a Carathéodory-type multivalued nonlinearity satisfying some monotonicity condition in the phase variables. We used the Yosida approximations of the linear part of the inclusion, the method of a priori estimates of solutions, and the topological degree method for condensing vector fields. As an example, we considered the existence and uniqueness of a solution to the Cauchy problem for a system governed by a perturbed subdifferential inclusion of a fractional diffusion type.
Synergistic Effect of Biosynthesized Silver Nanoparticles and Natural Phenolic Compounds against Drug-Resistant Fish Pathogens and Their Cytotoxicity: An In Vitro Study
Authors: Essawy Ehab , Abdelfattah Mohamed S. , El-Matbouli Mansour , Saleh Mona
Published: January 2021

Fish pathogens causing disease outbreaks represent a major threat to aquaculture industry and food security. The aim of the presented study is to develop safe and effective bioactive agents against two bacterial isolates: Aeromonas hydrophila and Pseudomonas fluorescens. We employed a broth microdilution method to investigate the antibacterial effect of biosynthesized silver nanoparticles (AgNPs); rutin, a natural flavonoid extracted from Ruta graveneoles; and heliomycin, a secondary metabolite produced by marine actinomycetes AB5, as monotherapeutic agents. Moreover, AgNPs in combination with rutin (AgNP + R) and heliomycin (AgNPs + H) were examined for their synergistic effect. The cytotoxic effect of individual bioactive compounds and in combination with AgNPs was investigated on epithelioma papulosum cyprini (EPC) fish cell lines. Individual treatment of AgNPs, rutin, and heliomycin exhibited a dose-dependent antimicrobial activity against A. hydrophila and P. fluorescens. Rutin minimum inhibitory concentration (MIC) showed the lowest cytotoxicity when tested on EPC cell lines, while heliomycin MIC was highly cytotoxic. Combined subtherapeutic doses of AgNPs + R and AgNPs + H displayed additive and synergistic effects against A. hydrophila and P. fluorescens, respectively, with improved results and relative safety profile. The study findings demonstrate that a combination of AgNPs and natural bioactive compounds may represent novel therapeutics fighting fish pathogens potentially affecting the fish farming industry.
Affective Temperaments and Illness Severity in Patients with Bipolar Disorder
Authors: Luciano Mario , Steardo Luca , Sampogna Gaia , Caivano Vito , Ciampi Carmen , Del Vecchio Valeria , Di Cerbo Arcangelo , Giallonardo Vincenzo , Zinno Francesca , De Fazio Pasquale , Fiorillo Andrea
Published: January 2021

Background and objectives: Bipolar disorder (BD) is one of the most burdensome psychiatric illnesses, being associated with a negative long-term outcome and the highest suicide rate. Although affective temperaments can impact on BD long-term outcome, their role remains poorly investigated. The aims of the present study are to describe the clinical characteristics of patients with BD more frequently associated with the different affective temperaments and to assess the relation between affective temperaments and severity of clinical picture in a sample of patients with BD. Materials and Methods: A total of 199 patients have been recruited in the outpatients units of two university sites. Patients’ psychiatric symptoms, affective temperaments, and quality of life were investigated through validated assessment instruments. Results: Predominant cyclothymic and irritable temperaments are associated to higher number of relapses, poorer quality of life, higher rates of aggressive behaviors, and suicide attempts. Conversely, the predominant hyperthymic disposition was a protective factor for several outcome measures, including relapse rate, severity of anxiety, depressive and manic symptoms, suicidality, and earlier age at onset. One limitation of the present study is that the recruitment took place in two university sites; therefore, our findings cannot be fully generalized to the whole community of BD patients. Other limitations are the lack of a control group and the cross-sectional design of the study. Conclusions: The early identification of affective temperaments can help clinicians to identify those BD patients who are more likely to show a poor long-term outcome. An early screening of affective temperaments can be useful to develop targeted integrated pharmacological and psychosocial interventions.
Therapeutic Strategies for the Treatment of Chronic Hyperuricemia: An Evidence-Based Update
Authors: Cicero Arrigo F. G. , Fogacci Federica , Kuwabara Masanari , Borghi Claudio
Published: January 2021

This article aims to critically review the evidence on the available therapeutic strategies for the treatment of hyperuricemia. For this reason, several papers were reviewed. Xanthine oxidase inhibitors are the safest and most effective uric acid lowering drugs for the management of chronic hyperuricemia, while the efficacy of uricosuric agents is strongly modulated by pharmacogenetics. Emergent drugs (lesinurad, peglotidase) were found to be more effective for the acute management of refractory hyperuricemia, but their use is supported by a relatively small number of clinical trials so that further well-designed clinical research is needed to deepen their efficacy and safety profile.
Digital Customized Titanium Mesh for Bone Regeneration of Vertical, Horizontal and Combined Defects: A Case Series
Authors: De Santis Daniele , Gelpi Federico , Verlato Giuseppe , Luciano Umberto , Torroni Lorena , Antonucci Nadia , Bernardello Fabio , Zarantonello Morris , Nocini Pier Francesco
Published: January 2021

Background and Objective: Guided bone regeneration allows new bone formation in anatomical sites showing defects preventing implant rehabilitation. Material and Methods: The present case series reported the outcomes of five patients treated with customized titanium meshes manufactured with a digital workflow for achieving bone regeneration at future implant sites. A significant gain in both width and thickness was achieved for all patients. Results: From a radiographic point of view (CBTC), satisfactory results were reached both in horizontal and vertical defects. An average horizontal gain of 3.6 ± 0.8 mm and a vertical gain of 5.2 ± 1.1 mm. Conclusions: The findings from this study suggest that customized titanium meshes represent a valid method to pursue guided bone regeneration in horizontal, vertical or combined defects. Particular attention must be paid by the surgeon in the packaging of the flap according to a correct method called the “poncho” technique in order to reduce the most frequent complication that is the exposure of the mesh even if a partial exposure of one mesh does not compromise the final outcome of both the reconstruction and the healing of the implants.
Encephalic Leukocytoclastic Vasculitis during Treatment with Sunitinib for Renal Cell Carcinoma: A Case Report
Authors: Massucci Maria , Mollica Veronica , Rizzo Alessandro , Ventrella Laura , Maggio Ilaria , Manuzzi Lisa , Gatto Lidia , Brandi Giovanni , Massari Francesco
Published: January 2021

Renal cell carcinoma is a malignant tumor that arises in the kidney parenchyma. For many years, sunitinib has represented the mainstay of medical treatment for metastatic renal cell carcinoma. Herein, we present the case of a 66-year-old woman with metastatic clear cell renal carcinoma undergoing treatment with sunitinib for two years that developed encephalic leukocytoclastic vasculitis, probably due to a paraneoplastic syndrome.
Multilayered PVDF-HFP Porous Separator via Phase Separation and Selective Solvent Etching for High Voltage Lithium-Ion Batteries
Authors: Bui Van-Tien , Nguyen Van-Toan , Nguyen Ngoc-Anh , Umapathi Reddicherla , Larina Liudmila L. , Kim Jong Heon , Kim Hyun-Suk , Choi Ho-Suk
Published: January 2021

The development of highly porous and thin separator is a great challenge for lithium-ion batteries (LIBs). However, the inevitable safety issues always caused by poor mechanical integrity and internal short circuits of the thin separator must be addressed before this type of separator can be applied to lithium-ion batteries. Here, we developed a novel multilayer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane with a highly porous and lamellar structure, through a combination of evaporation-induced phase separation and selective solvent etching methods. The developed membrane is capable of a greater amount of electrolyte uptake and excellent electrolyte retention resulting from its superior electrolyte wettability and highly porous structure, thereby offering better electrochemical performance compared to that of a commercial polyolefin separator (Celgard). Moreover, benefiting from the layered configuration, the tensile strength of the membrane can reach 13.5 MPa, which is close to the mechanical strength of the Celgard type along the transversal direction. The elaborate design of the multilayered structure allows the fabrication of a new class of thin separators with significant improvements in the mechanical and electrochemical performance. Given safer operation, the developed multilayer membrane may become a preferable separator required for high-power and high-energy storage devices.
Development of Polymeric Membranes for Oil/Water Separation
Authors: Hussain Arshad , Al-Yaari Mohammed
Published: January 2021

In this work, the treatment of oily wastewater was investigated using developed cellulose acetate (CA) membranes blended with Nylon 66. Membrane characterization and permeation results in terms of oil rejection and flux were compared with a commercial CA membrane. The solution casting method was used to fabricate membranes composed of CA and Nylon 66. Scanning Electron Microscopy (SEM) analysis was done to examine the surface morphology of the membrane as well as the influence of solvent on the overall structure of the developed membranes. Mechanical and thermal properties of developed blended membranes and a commercial membrane were examined by thermogravimetric analysis (TGA) and universal (tensile) testing machine (UTM). Membrane characterizations revealed that the thermal and mechanical properties of the fabricated blended membranes better than those of the commercial membrane. Membrane fluxes and rejection of oil as a function of Nylon 66 compositions and transmembrane pressure were measured. Experimental results revealed that the synthetic membrane (composed of 2% Nylon 66 and Dimethyl Sulfoxide (DMSO) as a solvent) gave a permeate flux of 33 L/m2h and an oil rejection of around 90%, whereas the commercial membrane showed a permeate flux of 22 L/m2h and an oil rejection of 70%.
Comparison of Polypropylene and Ceramic Microfiltration Membranes Applied for Separation of 1,3-PD Fermentation Broths and Saccharomyces cerevisiae Yeast Suspensions
Authors: Tomczak Wirginia , Gryta Marek
Published: January 2021

In recent years, microfiltration (MF) has gained great interest as an excellent technique for clarification of biological suspensions. This paper addresses a direct comparison of efficiency, performance and susceptibility to cleaning of the ceramic and polymeric MF membranes applied for purification of 1,3-propanediol (1,3-PD) fermentation broths and suspensions of yeast Saccharomyces cerevisiae. For this purpose, ceramic, titanium dioxide (TiO2) based membranes and polypropylene (PP) membranes were used. It has been found that both TiO2 and PP membranes provide sterile permeate during filtration of 1,3-PD broths. However, the ceramic membrane, due to the smaller pore diameter, allowed obtaining a better quality permeate. All the membranes used were highly susceptible to fouling with the components of the clarified broths and yeast suspensions. The significant impact of the feed flow velocity and fermentation broth composition on the relative permeate flux has been demonstrated. Suitable cleaning agents with selected concentration and duration of action effectively cleaned the ceramic membrane. In turn, the use of aggressive cleaning solutions led to degradation of the PP membranes matrix. Findings of this study add to a growing body of literature on the use of ceramic and polypropylene MF membranes for the clarification of biological suspensions.
Experimental Correlation of Mechanical Properties of the Ti-6Al-4V Alloy at Different Length Scales
Authors: Tuninetti Víctor , Jaramillo Andrés Felipe , Riu Guiomar , Rojas-Ulloa Carlos , Znaidi Amna , Medina Carlos , Mateo Antonio Manuel , Roa Joan Josep
Published: January 2021

This article focuses on a systematic study of a Ti-6Al-4V alloy in order to extensively characterize the main mechanical properties at the macro-, micro- and submicrometric length scale under different stress fields. Hardness, elastic modulus, true stress–strain curves and strain-hardening exponent are correlated with the intrinsic properties of the α- and β-phases that constitute this alloy. A systematic characterization process followed, considering the anisotropic effect on both orthogonal crystallographic directions, as well as determining the intrinsic properties for the α-phase. An analytical relationship was established between the flow stress determined under different stress fields, testing geometries and length scales, highlighting that it is possible to estimate flow stress under compression and/or tensile loading from the composite hardness value obtained by instrumented nanoindentation testing.
Microstructure and Mechanical Properties of Dissimilar Friction Welding Ti-6Al-4V Alloy to Nitinol
Authors: Rehman Ateekh Ur , Babu Nagumothu Kishore , Talari Mahesh Kumar , Usmani Yusuf Siraj , Al-Khalefah Hisham
Published: January 2021

In the present study, a friction welding process was adopted to join dissimilar alloys of Ti-Al-4V to Nitinol. The effect of friction welding on the evolution of welded macro and microstructures and their hardnesses and tensile properties were studied and discussed in detail. The macrostructure of Ti-6Al-4V and Nitinol dissimilar joints revealed flash formation on the Ti-6Al-4V side due to a reduction in flow stress at high temperatures during friction welding. The optical microstructures revealed fine grains near the Ti-6Al-4V interface due to dynamic recrystallization and strain hardening effects. In contrast, the area nearer to the nitinol interface did not show any grain refinement. This study reveals that the formation of an intermetallic compound (Ti2Ni) at the weld interface resulted in poor ultimate tensile strength (UTS) and elongation values. All tensile specimens failed at the weld interface due to the formation of intermetallic compounds.
Intrinsic Fatigue Crack Growth in Al-Cu-Li-Mg-Zr Alloys: The Effect of the Iron Constituent Particles
Authors: Hao Min , Wang Liang , Chen Jun-Zhou , Wang Ren , Li Guo-Ai
Published: January 2021

The influence of iron (Fe)-containing constituent particles on the behavior of fatigue crack initiation and propagation of Al-Cu-Li-Mg-Zr alloys has been studied using fatigue crack growth (FCG) tests and in-situ fatigue testing and detailed metallographic examination based on scanning electron microscopy. Experimental results show that the alloy with a low level of Fe content (2A97-T3 sheet) exhibited a lower density, accompanying equivalent tensile strength and FCG rate compared to the damage-tolerant 2524-T3 sheet. It was found that the fatigue b growth of both alloys is dominated by transgranular mode, accompanied by intergranular expansion, and the high level of Fe content alloy presents more characteristics of intergranular. Coarse constituent particles were detrimental to the resistance against FCG. It is postulated here that the micro-cracks formed around the coarse Fe-containing particles are merged with the primary crack to produce a bridging effect, accelerating the growth of fatigue cracks in the alloy with a high level of Fe content.
Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate
Authors: Mladenović Ivana O. , Nikolić Nebojša D. , Lamovec Jelena S. , Vasiljević-Radović Dana , Radojević Vesna
Published: January 2021

The mechanical characteristics of electrochemically deposited copper coatings have been examined by application of two hardness composite models: the Chicot-Lesage (C-L) and the Cheng-Gao (C-G) models. The 10, 20, 40 and 60 µm thick fine-grained Cu coatings were electrodeposited on the brass by the regime of pulsating current (PC) at an average current density of 50 mA cm−2, and were characterized by scanning electron (SEM), atomic force (AFM) and optical (OM) microscopes. By application of the C-L model we determined a limiting relative indentation depth (RID) value that separates the area of the coating hardness from that with a strong effect of the substrate on the measured composite hardness. The coating hardness values in the 0.9418–1.1399 GPa range, obtained by the C-G model, confirmed the assumption that the Cu coatings on the brass belongs to the “soft film on hard substrate” composite hardness system. The obtained stress exponents in the 4.35–7.69 range at an applied load of 0.49 N indicated that the dominant creep mechanism is the dislocation creep and the dislocation climb. The obtained mechanical characteristics were compared with those recently obtained on the Si(111) substrate, and the effects of substrate characteristics such as hardness and roughness on the mechanical characteristics of the electrodeposited Cu coatings were discussed and explained.
Fatigue Failure Prediction of U-Notched ZK60 Magnesium Samples Using the Strain Energy Density Approach
Authors: Albinmousa Jafar
Published: January 2021

The light weight of magnesium alloys makes them a promising material in different potential industries, such as aerospace and automobile. In addition, magnesium alloys are attractive materials for biomedical applications due to their biocompatibility with the human body. The applications of these alloys in structural parts require an understanding of their fatigue behavior because they are usually subjected to time-varying loading. Furthermore, notches are inevitable in structural parts. Geometrical discontinuities weaken structures because they act as stress raisers. Localized cyclic plasticity around notches leads to crack formation and final failure. The main objective of this research was to investigate the fatigue failure of ZK60-T5 extrusion in the presence of a notch. U-notched specimens with a diameter of 16 mm, notch radius of 1.5 mm, and notch depth of 1.5 mm were machined along the extrusion direction. Cyclic tests were performed under completely reversed cyclic loading and ambient conditions. The results obtained from the cyclic tests of the U-notched specimens were compared with those of unnotched and V-notched specimens to assess the effects of both the presence and the geometry of a notch on fatigue life. The strain energy density approach was successfully used to analyze the fatigue behavior of the U-notch specimens.
Contact Geometry Modification of Friction-Welded Semi-Finished Products to Improve the Bonding of Hybrid Components
Authors: Behrens Bernd-Arno , Uhe Johanna , Petersen Tom , Nürnberger Florian , Kahra Christoph , Ross Ingo , Laeger René
Published: January 2021

To improve the bond strength of hybrid components when joined by friction welding, specimens with various front end surface geometries were evaluated. Rods made of aluminum AA6082 (AlSi1MgMn/EN AW-6082) and the case-hardening steel 20MnCr5 (AISI 5120) with adapted joining surface geometries were investigated to create both a form-locked and material-bonded joint. Eight different geometries were selected and tested. Subsequently, the joined components were metallographically examined to analyze the bonding and the resulting microstructures. The mechanical properties were tested by means of tensile tests and hardness measurements. Three geometrical variants with different locking types were identified as the most promising for further processing in a forming process chain due to the observed material bond and tensile strengths above 220 MPa. The hardness tests revealed an increase in the steel’s hardness and a softening of the aluminum near the transition area. Apparent intermetallic phases in the joining zone were analyzed by scanning electron microscopy (SEM) and an accumulation of silicon in the joining zone was detected by energy-dispersive X-ray spectroscopy (EDS).
On the Influence of the Microstructure upon the Fatigue and Corrosion Fatigue Behavior of UNS N07718
Authors: Engler Christopher Tom , Klapper Helmuth Sarmiento , Oechsner Matthias
Published: January 2021

Due to the challenging operational conditions occurring during drilling, e.g., in the oil and gas industry, the corrosion fatigue (CF) behavior of materials used in drillstring components needs to be well understood. The combination of cyclic mechanic loads and a corrosive environment can affect significantly the integrity of a material, which has to be taken into account when selecting and qualifying materials for drilling equipment. Nickel alloys such as the precipitation-hardenable alloy 718 (UNS N07718) are widely used in many industrial applications including subterranean drilling. In the present study, the fatigue and CF behavior of alloy 718 in three different metallurgical conditions was investigated. The CF behavior of the different conditions was determined using customized rotating bending machines enabling testing in a simulated drilling environment at 125 °C. Results have shown that the fatigue and CF strength of alloy 718 is affected by its microstructural particularities, for instance, the amount of strengthening phases and δ-phase.
Effect of Asymmetric Material Flow on the Microstructure and Mechanical Properties of 5A06 Al-Alloy Welded Joint by VPPA Welding
Authors: Yan Zhaoyang , Chen Shujun , Jiang Fan , Zheng Xing , Tian Ooi , Cheng Wei , Ma Xinqiang
Published: January 2021

The microstructure, texture, and mechanical properties of the asymmetric welded joint in variable polarity plasma arc (VPPA) welding were studied and discussed in this paper. The asymmetric welded joint was obtained through horizontal welding, where the effect of gravity caused asymmetric material flow. The results showed that the grain size and low angle grain boundary (LAGB) at both sides of the obtained welded joint were asymmetric; the grain size differed by a factor of 1.3. The average grain size of the Base Metal (BM), Lower-weld zone (WZ) and Upper-WZ were 25.73 ± 1.25, 37.87 ± 1.89 and 49.92 ± 2.49 µm, respectively. There is discrepancy between the main textures in both sides of the welded joint. However, the effect of asymmetric metal flow on the weld texture was not significant. The micro-hardness distribution was inhomogeneous, the lowest hardness was observed in regions with larger grain sizes and smaller low angle grain boundary. During tensile strength tests, the specimens fractured at the position with the lowest hardness although it has reached 89.2% of the strength of the BM. Furthermore, the effect of asymmetric metal flow and underlying causes of asymmetric weld properties in VPPA horizontal welding have been discussed and analyzed.
Technological Typomorphic Associations in Caustobiolites and Methods of Their Extraction
Authors: Romashev Artyom , He Dongsheng , Aleksandrova Tatiana , Nikolaeva Nadezhda
Published: January 2021

Heavy oil is considered as a multipurpose complex mineral, and the processing of heavy oils as a “complex problem”, aimed both at increasing the yield of light fractions and “transport” ability of oil, and at extracting metals from heavy asphaltene resinous fraction. The recovery of heavy metals (such as vanadium, nickel, titanium, iron, etc.) from heavy oil was performed by cavitation extraction technology with the use of light hydrocarbon solvents and chemical extractants, including a stage of extraction in an ultrasonic field with separation of insoluble fraction of asphaltenes in which a significant part of initial heavy metals and sulfur is concentrated, followed by re-extraction of metals and magnetic separation of metal aggregates.