bluuebunny/crossref_metadata_2025 huggingface dataset:
Strength of Partially Encased Steel-Concrete Composite Column for Modular Building Structures
Authors: Park Keum-Sung , Lee Sang-Sup , Bae Kyu-Woong , Moon Jiho
Published: September 2022

Modular structural systems have been used increasingly for low- and mid-rise structures such as schools and apartment buildings, and applications are extending to high-rise buildings. To provide sufficient resistance and economical construction of the high-rise modular structural system, the steel-concrete composite unit modular structure was proposed. The proposed composite unit modular system consists of the composite beam and the partially encased nonsymmetrical composite column. The outside steel member of the composite column has an open section, and is manufactured using a pressed forming procedure so that easy joining connecting work and manufacturing cost reductions are possible. However, the design methods are complicated due to the inherent nonsymmetrical properties of the section. Therefore, in this study, the focus was made on the strength evaluation and development of design methods for the partially encased nonsymmetrical steel-concrete composite column. Four full-scale specimens were constructed and tested. The experimental study focused on the effect of the slenderness ratio of the column, eccentricity, and the through bars on the strength of such columns. Additionally, the P–M interaction curve to estimate the strength of the proposed composite column under general combined loading was developed based on the plastic stress distribution method. The results indicate that the through bars are needed to delay the local buckling and distribute the loading uniformly throughout the composite column. Finally, the proposed design methods provide a conservative strength prediction of the proposed composite column.
Recycling of Flexible Polyurethane Foams by Regrinding Scraps into Powder to Replace Polyol for Re-Foaming
Authors: Guo Lei , Wang Wenchao , Guo Xiurui , Hao Kuanfa , Liu Haichao , Xu Yuan , Liu Gongxu , Guo Shouyun , Bai Lichen , Ren Donghui , Liu Fumin
Published: September 2022

In the context of protecting the ecological environment and carbon neutrality, high-value recycling of flexible polyurethane foam (F-PUF) scraps, generated in the production process, is of great significance to save petroleum raw materials and reduce energy consumption. In the present study, F-PUF scraps were ground into powder by strong shear regrinding using two-roll mill and then reused as a partial replacement of polyol for re-foaming. A series of characterizations were employed to investigate the effect of milling cycles, roller temperatures, and content of the powder on the properties of the powder and F-PUF containing powder. It was revealed that the mechanochemical effect induced breaking of the cross-linking structure and increased activity of the powder. The volume mean diameter (VMD) of powder prepared with 7 milling cycles, at room temperature, is about 97.73 μm. The microstructure and density of the F-PUF containing powder prepared in the above-mentioned manner to replace up to 15 wt.% polyol, is similar to the original F-PUF, with resilience 49.08% and compression set 7.8%, which indicates that the recycling method will play an important role in industrial applications.
Adsorption of Non-Steroidal Anti-Inflammatory Drugs on Alginate-Carbon Composites—Equilibrium and Kinetics
Authors: Wasilewska Małgorzata , Deryło-Marczewska Anna
Published: September 2022

In this work, alginate–carbon composites with different active carbon content were synthesized and studied by various techniques. The obtained materials can be used as adsorbents in the processes of removing organic pollutants from water. In this study, the effect of the immobilization of activated carbon in calcium alginate was investigated. Textural properties were determined by measuring low-temperature nitrogen adsorption/desorption isotherms. The largest specific surface area was recorded for ALG_C8 and amounted to 995 m2/g. The morphology of alginate materials was determined on the basis of scanning electron microscopy. The adsorption properties were estimated based on the measurements of equilibrium and adsorption kinetics. The highest sorption capacities were 0.381 and 0.873 mmol/g for ibuprofen and diclofenac, respectively. The generalized Langmuir isotherm was used to analyze the equilibrium data. A number of equations and kinetic models were used to describe the adsorption rate data, including first (FOE) and second (SOE) order kinetic equations, 1,2-mixed-order kinetic equation (MOE), fractal-like MOE equation (f-MOE), multi-exponential equation (m-exp), in addition to diffusion models: intraparticle diffusion model (IDM) and pore diffusion model (PDM). Thermal stability was determined on the basis of data from thermal analysis in an atmosphere of synthetic air.
Sol–Gel Synthesis of Endodontic Cements: Post-Synthesis Treatment to Improve Setting Performance and Bioactivity
Authors: Song Xiaozhe , Díaz-Cuenca Aránzazu
Published: September 2022

The sol–gel process is a wet chemical technique that allows very fine control of the composition, microstructure, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. In this work, the influence of different sol–gel synthesis variables on the preparation of endodontic cement based on calcium silicate with Ca/Si stoichiometry equal to 3 was studied. Starting from the most optimal hydraulic composition selected, a novel second post-synthesis treatment using ethanol was essayed. The effects of the tested variables were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption, and Gillmore needles to determine the setting time and simulated body fluid (SBF) immersion to measure the bioactive response in vitro. The results indicated that the sol–gel technique is effective in obtaining bioactive endodontic cements (BECs) with high content of the hydraulic compound tricalcium silicate (C3S) in its triclinic polymorph. The implementation of a novel post-synthesis treatment at room temperature using ethanol allows obtaining a final BEC product with a finer particle size and a higher CaCO3 content, which results in an improved material in terms of setting time and bioactive response.
Flexural Response of Axially Restricted RC Beams: Numerical and Theoretical Study
Authors: Hu Han , Lopes Sergio M. R. , Lopes Adelino V. , Lou Tiejiong
Published: September 2022

Reinforced concrete (RC) frame beams are subject to axial restriction at the ends, which plays an important role in the nonlinear behavior of these beams. This paper presents a numerical and theoretical investigation into the flexural behavior of RC beams axially restricted with external steel or fiber reinforced polymer (FRP) reinforcement. A numerical procedure for RC beams axially restricted with external reinforcement has been developed and it is verified against available experimental results. A numerical parametric study is then performed on axially restricted RC beams, focusing on the effect of type, area, and depth of external reinforcement. The results show that axial restriction increases the post-cracking stiffness and ultimate load-carrying capacity but reduces the flexural ductility. The ultimate stress in external reinforcement is substantially impacted by reinforcement type, area, and depth. A simplified model is developed to predict the ultimate load of RC beams axially restricted with external steel/FRP reinforcement. The predictions of the proposed simplified model agree favorably with the numerical results. The correlation coefficient for the ultimate load is 0.984, and the mean difference is −2.11% with a standard deviation of 3.62%.
Study on the Effect of Pre-Refinement and Heat Treatment on the Microstructure and Properties of Hypoeutectic Al-Si-Mg Alloy
Authors: Lin Ling , Zhou Lian , Xie Yu , Bai Weimin , Li Faguo , Xie Ying , Lu Mingxin , Wang Jue
Published: September 2022

Hypoeutectic Al-Si-Mg alloys with a silicon content of around 10 wt % are widely used in the aerospace and automotive fields due to their excellent casting properties. However, the occurrence of “silicon poisoning” weakens the refinement effect of a conventional refiner system such as Al-5Ti-1B. In this paper, we proposed the “pre-refinement” method to avoid the “Si poisoning” to recover the refinement effect of Al-5Ti-1B. The core concept was to adjust the order of adding the Si element to form the TiAl3 before forming the Ti-Si intermetallic compound. To prove the effectiveness of the “pre-refinement” method, three alloys of “pre-refinement”, “post-refinement”, and “non-refinement” of an Al-10Si-0.48Mg alloy were prepared and characterized in as-cast and heat-treatment states. The results showed that the average grain diameter of the “pre-refinement” alloy was 60.19% smaller than that of the “post-refinement” one and 81.34% smaller than that of the “non-refinement” one, which demonstrated that the proposed method could effectively avoid the “silicon poisoning” effect. Based on a refined grain size, the “pre-refinement” Al-10Si-0.48Mg alloy showed the best optimization effect in mechanical properties after a solid-solution and subsequent aging heat treatments. The best mechanical properties were found in the “pre-refinement” alloy with 2 h of solid solution treatment and 10 h of aging treatment: a hardness of 92 HV, a tensile strength of 212 MPa, and an elongation of 20%.
Residual Stress Build-Up in Aluminum Parts Fabricated with SLM Technology Using the Bridge Curvature Method
Authors: Ma Quoc-Phu , Mesicek Jakub , Fojtik Frantisek , Hajnys Jiri , Krpec Pavel , Pagac Marek , Petru Jana
Published: September 2022

In metal 3D printing with Selective Laser Melting (SLM) technology, due to large thermal gradients, the residual stress (RS) distribution is complicated to predict and control. RS can distort the shape of the components, causing severe failures in fabrication or functionality. Thus, several research papers have attempted to quantify the RS by designing geometries that distort in a predictable manner, including the Bridge Curvature Method (BCM). Being different from the existing literature, this paper provides a new perspective of the RS build-up in aluminum parts produced with SLM using a combination of experiments and simulations. In particular, the bridge samples are printed with AlSi10Mg, of which the printing process and the RS distribution are experimentally assessed with the Hole Drilling Method (HDM) and simulated using ANSYS and Simufact Additive. Subsequently, on the basis of the findings, suggestions for improvements to the BCM are made. Throughout the assessment of BCM, readers can gain insights on how RS is built-up in metallic 3D-printed components, some available tools, and their suitability for RS prediction. These are essential for practitioners to improve the precision and functionality of SLM parts should any post-subtractive or additive manufacturing processes be employed.
Extraction of Alkalis from Silicate Materials PART 2—Crystalline Silicate Materials
Authors: Kotsay Galyna , Szewczenko Wiktor
Published: September 2022

A feature of silicate materials is that they can exist in two antagonistic states—amorphous and crystalline. In both cases, alkalis, which are always present in chemical compositions, play an important role. A feature of alkalis in the composition of silicate materials is that at certain stages of the synthesis of products, they play a positive role, reducing the temperature of synthesis, but worsening the properties of these products at the stage of their operation. Synthesis products should be understood as important building materials such as building glass and cement. It is known that the performance properties of glass and cement can be improved by the extraction of alkalis. In the first part of the article, the issues of extraction of alkalis in amorphous silicate materials-inorganic glasses were considered. This article presents the results of studies on the extraction process of alkalis in crystalline silicate materials-cement.
Reducing Compaction Temperature of Asphalt Mixtures by GNP Modification and Aggregate Packing Optimization
Authors: Yan Tianhao , Turos Mugurel , Le Jia-Liang , Marasteanu Mihai
Published: September 2022

Compaction of hot mix asphalt (HMA) requires high temperatures in the range of 125 to 145 °C to ensure the fluidity of asphalt binder and, therefore, the workability of asphalt mixtures. The high temperatures are associated with high energy consumption, and higher NOx emissions, and can also accelerate the aging of asphalt binders. In previous research, the authors have developed two approaches for improving the compactability of asphalt mixtures: (1) addition of Graphite Nanoplatelets (GNPs), and (2) optimizing aggregate packing. This research explores the effects of these two approaches, and the combination of them, on reducing compaction temperatures while the production temperature is kept at the traditional levels. A reduction in compaction temperatures is desired for prolonging the paving window, extending the hauling distance, reducing the energy consumption for reheating, and for reducing the number of repairs and their negative environmental and safety effects, by improving the durability of the mixtures. A Superpave asphalt mixture was chosen as the control mixture. Three modified mixtures were designed, respectively, by (1) adding 6% GNP by the weight of binder, (2) optimizing aggregate packing, and (3) combining the two previous approaches. Gyratory compaction tests were performed on the four mixtures at two compaction temperatures: 135 °C (the compaction temperature of the control mixture) and 95 °C. A method was proposed based on the gyratory compaction to estimate the compaction temperature of the mixtures. The results show that all the three methods increase the compactability of mixtures and thus significantly reduce the compaction temperatures. Method 3 (combining GNP modification and aggregate packing optimization) has the most significant effect, followed by method 1 (GNP modification), and method 2 (aggregate packing optimization).
Laser Surface Alloying of Sintered Stainless Steel
Authors: Dudek Agata , Lisiecka Barbara , Radek Norbert , Orman Łukasz J. , Pietraszek Jacek
Published: September 2022

A characteristic feature of sintered stainless steel (SSS) is its porosity. Porosity results in a lower density of steel, making attractive components for producing lightweight structures and materials used in industry (e.g., the automotive industry or aerospace). Scientists also observe that porosity adversely affects steel’s properties, especially its strength properties. One of the proposals for improving the discussed properties is the use of surface treatment of sintered stainless steels, e.g., with the use of concentrated energy sources such as plasma beams or laser beams. However, this proposal is an incidental subject of research, which is not justified from the point of view of the obtained research results presented by a few research groups. In this study, the surface modification (surface treatment) of sintered stainless steel was presented. The authors proposed the use of two surface treatments in order to compare them and obtain the best results. The first treatment was the deposit of Cr3C2–NiCr coatings on SSS surfaces using the atmospheric plasma spraying (APS) method. The second treatment was to create surface layers on SSSs by laser alloying the surface with a CO2 laser. Due to high precision and ease of automation, the most common methods in surface alloying treatment are laser technologies. This research’s main aim was to analyze the microstructure and strength properties of the SSS surface layer. The research confirms that applying the Cr3C2–NiCr coating and modifying the surface layer through the laser alloying method improves the mechanical properties of SSSs.
Synthesis of NiAl Intermetallic Compound under Shock-Wave Extrusion
Authors: Malakhov Andrey , Shakhray Denis , Denisov Igor , Galiev Fanis , Seropyan Stepan
Published: September 2022

This paper presents the implementation of the first stage of a study on the synthesis of the intermetallic compound in the Ni-Al system under shock-wave extrusion (SWE). A method was developed and experiments involving SWE of the reactive Ni–Al powder mixture were carried out. As a result, it was possible to obtain up to 56 vol.% of the final product and achieve 100% synthesis of NiAl. The results of metallographic analysis indicate that the process of high-velocity collapse of the tube created conditions for the formation of a cumulative flow, which directly affects the phase formation in NiAl. It was shown that the presence of the central hole in the powder sample reduced the effect of the Mach stem on the homogeneity of the NiAl structure. It was also determined that with a central hole with a 5 mm diameter, the effect of the Mach stem could not be observed at all. The goals of further studies are achieving 90–100 vol.% of the final product and reducing the porosity in the final product. Preliminary experimental studies have shown great potential for SWE to produce composite metal–intermetallic materials.
An Experimental and Analytical Study on a Damage Constitutive Model of Engineered Cementitious Composites under Uniaxial Tension
Authors: Zhao Dapeng , Wang Changjun , Li Ke , Zhang Pengbo , Cong Lianyou , Chen Dazhi
Published: September 2022

Engineered cementitious composites (ECC) exhibit ultra-high ductility and post-cracking resistance, which makes it an attractive material in civil engineering. First, a monotonic uniaxial tensile test was performed, considering the effects of polyvinyl alcohol (PVA) fiber volume content and water-binder ratio. Then, the effects of the above variables on the tensile characteristics including the tensile stress–strain relationship, deformation capacity, and fracture energy were investigated based on test results; and when the water-binder ratio is 0.28 and the fiber volume content is 2%, the deformation performance of ECC is improved most significantly. Next, combined with damage mechanics theory, the damage evolution mechanism of ECC in monotonic uniaxial tension was revealed, based on which the damage factor and damage evolution equation of ECC were developed and the expressions of model parameters were proposed. Moreover, the comparison between the proposed model and test results demonstrated the accuracy of the proposed model. Finally, to further verify the feasibility of the proposed model, a finite element (FE) simulation analysis of the tensile performance of high-strength stainless steel wire rope (HSSWR) reinforced ECC by adopting the proposed model was compared with test results and the simulation analysis results by using anther existing model, the “trilinear model of ECC”. The comparison shows that the proposed model in this paper can predict more accurately.
Effect of Curing Temperature on the Properties of a MgO-SiO2-H2O System Prepared Using Dead-Burned MgO
Authors: Cheng Fuan , Hu Yaru , Song Qiang , Nie Jiao , Su Jiahao , Chen Yanxin
Published: September 2022

The hydration of M-S-H prepared using silica fume (SF) and dead-burned MgO cured at 20 °C, 50 °C, and 80 °C was investigated, and the properties and performance of this M-S-H were measured. The formation of M-S-H was characterized using XRD, FTIR, TGA, and 29Si MAS-NMR. Results show that the compressive strength of paste prepared using MgO calcined at 1450 °C for 2 h reached 25 MPa after 28 d. The shrinkage of mortar made with low reactivity MgO was lower than that made with high reactivity MgO. The pH value of MgO/SF paste mixed with dead-burned MgO did not exceed 10.4 at room temperature. The shrinkage of M-S-H prepared using dead-burned MgO was less than that prepared using more active MgO, and its strength did not decrease over time. No (or only a small amount of) Mg(OH)2 was formed, which is why the strength of M-S-H prepared with dead-burned MgO continually increased, without decreasing. The promotion of curing temperature favor process of MgO hydration and is beneficial for degree of silica polymerization. The sample cured in 50 °C water showed the highest relative degree of reaction.
A Measurement Solution of Face Gears with 3D Optical Scanning
Authors: Lu Xinxin , Zhao Xing , Hu Bo , Zhou Yuansheng , Cao Zhezhen , Tang Jinyuan
Published: September 2022

Gears are usually measured by the contact metrology method in gear measuring centers or coordinate measuring machines. Recently, three-dimensional (3D) optical scanning, a non-contact metrology method, has been applied in the industry as an advanced measurement technology mainly due to its high efficiency. However, its applications to gears with complicated geometry, such as face gears, are still limited due to its relatively low accuracy and the void of related measurement solutions. In this work, an accurate measurement solution with 3D optical scanning is proposed for the tooth surface deviations of orthogonal face gears. First, point cloud collection is carried out by the 3D scanner. Furthermore, the measurement solution is implemented with a three-stage algorithm by aligning point clouds with the design model. Subsequently, 3D modeling is studied by numbering the points and reconstructing the real tooth surfaces. An example with a measurement experiment and loaded tooth contact analysis is given to show the validity of the proposed method.
Peculiarities of the Phase Formation during Electroconsolidation of Al2O3–SiO2–ZrO2 Powders Mixtures
Authors: Krzysiak Zbigniew , Gevorkyan Edwin , Nerubatskyi Volodymyr , Rucki Mirosław , Chyshkala Volodymyr , Caban Jacek , Mazur Tomasz
Published: September 2022

This paper is devoted to the sintering process of Al2O3–SiO2–ZrO2 ceramics. The studied method was electroconsolidation with directly applied electric current. This method provides substantial improvements to the mechanical properties of the sintered samples compared to the traditional sintering in the air. The research covered elemental and phase analysis of the samples, which revealed phase transition of high-alumina solid solutions into mullite and corundum. Zirconia was represented mainly by tetragonal phase, but monoclinic phase was present, too. Electroconsolidation enabled samples to reach a density of 3.0 g/cm3 at 1300 °C, while the sample prepared by traditional sintering method obtained it only at 1700 °C. For the composite Al2O3—20 wt.% SiO2—10 wt.% ZrO2 fabricated by electroconsolidation, it was demonstrated that fracture toughness was higher by 20–30%, and hardness was higher by 15–20% compared to that of samples sintered traditionally. Similarly, the samples fabricated by electroconsolidation exhibited elastic modulus E higher by 15–20%. The hypothesis was proposed that the difference in mechanical and physical properties could be attributed to the peculiarities of phase formation processes during electroconsolidation.
Liquid-Phase-Assisted Catalytic Nitridation of Silicon and In Situ Growth of α-Si3N4
Authors: Liu Zhenglong , Chai Zhinan , Yu Chao , Ding Jun , Deng Chengji , Li Xiangcheng , Zhu Hongxi
Published: September 2022

Si3N4 powders were synthesized with Fe, Co, or Ni as catalysts using Si powder at 1250 °C in a nitrogen atmosphere by liquid-phase-assisted catalytic nitridation synthesis (LPA–CNS). The catalytic effects of the metals on the nitridation of silicon powder were investigated by mixing the powder with 2 wt% by mass of Fe, Co, or Ni in a high-temperature liquid phase in flowing nitrogen. The α-Si3N4 micro-morphology could be effectively changed by adjusting the type of catalyst in the initial reaction mixtures. Fe, Co, and Ni promoted the formation of α-Si3N4 at 1250 °C and controlled the morphology of the α-Si3N4 particles. The hexagonal flakes of α-Si3N4 with a better defined morphology were obtained using Ni as the catalyst, compared to that obtained from the other two catalysts.
Comparison of Shielding Material Dispersion Characteristics and Shielding Efficiency for Manufacturing Medical X-ray Shielding Barriers
Authors: Kim Seon-Chil
Published: September 2022

During medical diagnoses, X-ray shielding barriers are used to protect against direct and indirect X-rays. Currently, lead is used as the primary material for shielding barriers; however, the demand for eco-friendly shielding barriers has been increasing. Conventionally, shielding barriers are manufactured using a mechanically bonded combination of lead and aluminum; however, in this study, a plastic-based injection-molded product was developed using tungsten as an eco-friendly alternative to lead. A new process technology was required for mixing tungsten—which can be difficult to process—with a polymer. Consequently, the mixing conditions within the injection molding machine and the related compounding technology factors were analyzed. The process technology considered the pre-mixing method using powdery polymer, particle dispersion method, number of screw rotations, and amount of filler input. The product’s shielding performance was then analyzed. The tungsten content of the 2-mm thick barrier manufactured using the proposed method was 90 wt%, and the lead equivalent was 0.321 mmPb. To increase the effectiveness of injection molding in the manufacturing process, specific hourly compounding conditions were proposed. Consequently, the process technology method developed in this study can be considered suitable for manufacturing various shielding barriers.
Investigating the Mechanical and Durability Characteristics of Fly Ash Foam Concrete
Authors: Li Sheng , Li Hongbo , Yan Changyu , Ding Yongfa , Zhang Xuanshuo , Zhao Jing
Published: September 2022

Although fly ash foam concrete (FAFC) is lightweight, heat-retaining, and insulating, its application options are constrained by its weak construction and short lifespan. The effects of various dosage ratios of the foaming agent (i.e., hydrogen peroxide), silica fume, and polypropylene fiber on the dry density, compressive strength, thermal insulation performance, pore structure parameters, and durability of FAFC were analyzed in this study, which sought to address the issues of low strength and low durability of FAFC. According to the findings, there is a negative correlation between the amount of hydrogen peroxide (as the foaming agent) and compressive strength, and, as the silica fume and polypropylene fiber (PP fiber) content rise, the strength will initially rise and then fall. The distribution of pore sizes gradually shifts from being dominated by small pores to large pores as the amount of foaming agent increases, while the porosity and average pore size gradually decrease. When the hydrogen peroxide content is 5%, the pore shape factor is at its lowest. The pore size distribution was first dominated by a small pore size and thereafter by a large pore size when the silica fume and PP fiber concentration increased. Prior to increasing, the porosity, average pore size, and pore shape factor all decreased. Additionally, the impact of PP fiber on the freeze–thaw damage to FAFC was also investigated at the same time. The findings indicate that the freeze–thaw failure of FAFC is essentially frost heave failure of the pore wall. The use of PP fiber is crucial for enhancing FAFC’s ability to withstand frost. The best frost resistance is achieved at 0.4% PP fiber content. In conclusion, the ideal ratio for overall performance was found to be 5% hydrogen peroxide content, 4% silica fume content, and 0.1% polypropylene fiber content. The results obtained could be applied in different fields, such as construction and sustainable materials, among others.
Use of Hydrogen–Rich Gas in Blast Furnace Ironmaking of V–bearing Titanomagnetite: Mass and Energy Balance Calculations
Authors: Gao Xudong , Zhang Run , You Zhixiong , Yu Wenzhou , Dang Jie , Bai Chenguang
Published: September 2022

The iron and steel industry is a major CO2 emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace.
Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology
Authors: Gao Zeng , Qin Zhen , Lu Qingsong
Published: September 2022

3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried out at a relatively high temperature, causing the assembled heat exchanger to be partially molten or easily deformed. A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology and then applied to CAB of 3003 aluminum alloy in this research. The solidus and liquidus of brazing filler metal was 513.21 °C and 532.48 °C. All elements were evenly distributed and free from elemental segregation. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm. As the brazing temperature reached 575 °C, the void in the joint disappeared completely. The morphology of CuAl2 was sensitive to the brazing temperature and dwell time. The appearance of net-like CuAl2 brazed at 575 °C for 20 min was more beneficial to improve joint mechanical properties. The leakage rate of the joint was qualified to be 10−10 Pa·m3/s when the brazing temperature was 570 °C or higher. The maximum shear strength of 76.1 MPa can be obtained when the joint was brazed at 575 °C for 20 min. More dwell time induced growth of the interfacial layer and reduced joint shear strength. The open circuit potential and corrosion current density test indicated that the brazing filler metal Al-5.0Si-20.5Cu-2.0Ni had better corrosion resistance than that of 3003 aluminum alloy.
Research on Unbalanced Vibration Suppression Method for Coupled Cantilever Dual-Rotor System
Authors: Lu Jiaqiao , Zhang Xin , Pan Xin , Zhang Meng
Published: September 2022

The cantilever dual-rotor system is a typical structure of the blade output end of the open rotor engine and the coaxial output turboshaft engine. The excessive unbalanced vibration of a coupled cantilever dual-rotor system is one of the main factors limiting the application of the above engine type. In order to accurately describe the vibration coupling effect between the dual-rotor-intermediate bearings, the unbalanced response of the cantilever dual-rotor system is analyzed, and the self-sensitivity coefficient is proposed to guide the selection of measuring points and vibration suppression experiments for the dual-rotor system. On this basis, a new online automatic balance actuator applicable to this dual-rotor system is designed, and a feasibility experiment is carried out. The experimental results indicate that: (1) The self-sensitivity coefficient can be used as the basis for the actual vibration measuring point arrangement and unbalanced vibration suppression strategy of the dual-rotor system, and the proposed step-by-step vibration suppression strategy can reduce the vibration of the dual-rotor system by more than 80%. (2) The designed online automatic balance actuator can reduce the unbalanced vibration by 53% in 3.52 s. The proposed method in this study can provide guidance for the vibration suppression of the dual-rotor system.
Novel Authentication Protocols Based on Quadratic Diophantine Equations
Authors: Vijayarangan Avinash , Narayanan Veena , Natarajan Vijayarangan , Raghavendran Srikanth
Published: September 2022

The Diophantine equation is a strong research domain in number theory with extensive cryptography applications. The goal of this paper is to describe certain geometric properties of positive integral solutions of the quadratic Diophantine equation x12+x22=y12+y22(x1,x2,y1,y2>0), as well as their use in communication protocols. Given one pair (x1,y1), finding another pair (x2,y2) satisfying x12+x22=y12+y22 is a challenge. A novel secure authentication mechanism based on the positive integral solutions of the quadratic Diophantine which can be employed in the generation of one-time passwords or e-tokens for cryptography applications is presented. Further, the constructive cost models are applied to predict the initial effort and cost of the proposed authentication schemes.
Short-Sale Constraints and Stock Prices: Evidence from Implementation of Securities Refinancing Mechanism in Chinese Stock Markets
Authors: Su Larry , Homapour Elmina , Chiclana Francisco
Published: September 2022

Qualified Securities for Short-sale Refinancing (QSSR) is a unique trading mechanism that has exogenously increased the supply of loanable securities in Chinese stock markets. Using difference-in-differences (DID) methodology, this paper is the first to investigate whether and to what extent additions to the QSSR eligibility list affect short selling activities and stock price behaviors. The paper finds that stocks added to the QSSR list exhibit better liquidity and less negative skewness in returns than non-QSSR stocks. However, QSSR stocks are more volatile and display a higher frequency of extreme negative returns. In addition, on average, QSSR stocks experience larger negative abnormal returns (ARs) and cumulative abnormal returns (CARs) relative to non-QSSR stocks, and the difference in CARs is positively related to investor heterogeneity. The results indicate that short selling has mixed effects on stock prices. Removing short-sale constraints can improve liquidity and reduce price bubbles, but can also increase return volatility and amplify market crashes.
The Acute Achilles Tendon Rupture: An Evidence-Based Approach from the Diagnosis to the Treatment
Authors: Amendola Francesco , Barbasse Léa , Carbonaro Riccardo , Alessandri-Bonetti Mario , Cottone Giuseppe , Riccio Michele , De Francesco Francesco , Vaienti Luca , Serror Kevin
Published: September 2022

Background and Objective: Acute Achilles tendon rupture (AATR) is a common injury with a significant impact on daily living. Although various systematic reviews and meta-analyses have been written on the topic, no actual consensus exists on the best treatment. We aimed to collect the highest quality of evidence on the subject and to produce a document to which to refer, from the diagnosis to the final treatment. Material and Methods: Inclusion criteria were systematic reviews discussing Achilles tendon rupture, concerning either diagnostic criteria, classification, or treatment; English language; clearly stated inclusion and exclusion criteria for patients’ selection. Results: Thirteen systematic reviews were included in the study. A strong consensus exists about the higher risk of re-rupture associated with non-operative treatment and a higher risk of complications associated with surgical repair. Conclusions: The combination of minimally invasive repair and accelerated functional rehabilitation seems to offer the best results in the treatment of Achilles tendon rupture.
CT-Navigated Spinal Instrumentations–Three-Dimensional Evaluation of Screw Placement Accuracy in Relation to a Screw Trajectory Plan
Authors: Gubian Arthur , Kausch Lisa , Neumann Jan-Oliver , Kiening Karl , Ishak Basem , Maier-Hein Klaus , Unterberg Andreas , Scherer Moritz
Published: September 2022

Background and Objectives: In the literature, spinal navigation and robot-assisted surgery improved screw placement accuracy, but the majority of studies only qualitatively report on screw positioning within the vertebra. We sought to evaluate screw placement accuracy in relation to a preoperative trajectory plan by three-dimensional quantification to elucidate technical benefits of navigation for lumbar pedicle screws. Materials and Methods: In 27 CT-navigated instrumentations for degenerative disease, a dedicated intraoperative 3D-trajectory plan was created for all screws. Final screw positions were defined on postoperative CT. Trajectory plans and final screw positions were co-registered and quantitatively compared computing minimal absolute differences (MAD) of screw head and tip points (mm) and screw axis (degree) in 3D-space, respectively. Differences were evaluated with consideration of the navigation target registration error. Clinical acceptability of screws was evaluated using the Gertzbein–Robbins (GR) classification. Results: Data included 140 screws covering levels L1-S1. While screw placement was clinically acceptable in all cases (GR grade A and B in 112 (80%) and 28 (20%) cases, respectively), implanted screws showed considerable deviation compared to the trajectory plan: Mean axis deviation was 6.3° ± 3.6°, screw head and tip points showed mean MAD of 5.2 ± 2.4 mm and 5.5 ± 2.7 mm, respectively. Deviations significantly exceeded the mean navigation registration error of 0.87 ± 0.22 mm (p < 0.001). Conclusions: Screw placement was clinically acceptable in all screws after navigated placement but nevertheless, considerable deviation in implanted screws was noted compared to the initial trajectory plan. Our data provides a 3D-quantitative benchmark for screw accuracy achievable by CT-navigation in routine spine surgery and suggests a framework for objective comparison of screw outcome after navigated or robot-assisted procedures. Factors contributing to screw deviations should be considered to assure optimal surgical results when applying navigation for spinal instrumentation.
Malassezia Folliculitis following Triple Therapy for Cystic Fibrosis
Authors: Li Pomi Federica , Di Bartolomeo Luca , Vaccaro Mario , Lentini Maria , Cristadoro Simona , Lucanto Maria Cristina , Lombardo Mariangela , Costa Stefano , Borgia Francesco
Published: September 2022

Triple-combination therapy with elexacaftor, tezacaftor and ivacaftor has been recently approved for cystic fibrosis patients with at least one F508del mutation in the transmembrane conductance regulator of the cystic fibrosis gene. Among the adverse events of elexacaftor, tezacaftor and ivacaftor, the cutaneous ones have been rarely reported, mainly dealing with urticarial-like rashes. On this topic, we report two cases of Malassezia folliculitis following triple therapy administration in two young females. In the first patient, a papulopustular rush appeared before the folliculitis while in the second patient it was not preceded by other skin manifestations. The diagnosis was confirmed both by dermoscopy and histology. The prompt response to systemic antimycotic drugs provided further evidence for the causative role of Malassezia, requiring no discontinuation of cystic fibrosis therapy. We could hypothesize that the triple regimen treatment may induce changes in the skin microbiome, potentially able to favor colonization and proliferation of Malassezia species. Physicians should be aware of such associations to allow prompt diagnosis and early interventions, avoiding useless drug removal.
Cutting the First Turf to Heal Post-SSRI Sexual Dysfunction: A Male Retrospective Cohort Study
Authors: De Luca Rosaria , Bonanno Mirjam , Manuli Alfredo , Calabrò Rocco Salvatore
Published: September 2022

Post-SSRI sexual dysfunction (PSSD) is a set of heterogeneous sexual problems, which may arise during the administration of selective serotonin reuptake inhibitors (SSRIs) and persist after their discontinuation. PSSD is a rare clinical entity, and it is commonly associated with non-sexual concerns, including emotional and cognitive problems and poor quality of life. To date, however, no effective treatment is available. The aim of this study was to retrospectively evaluate the potential efficacy of the different treatments used in clinical practice in improving male PSSD. Of the 30 patients referred to our neurobehavioral outpatient clinic from January 2020 to December 2021, 13 Caucasian male patients (mean age 29.53 ± 4.57 years), previously treated with SSRIs, were included in the study. Patients with major depressive disorder and/or psychotic symptoms were excluded a priori to avoid overlapping symptomatology, and potentially reduce the misdiagnosis rate. To treat PSSD, we decided to use drugs positively affecting the brain dopamine/serotonin ratio, such as bupropion and vortioxetine, as well as other compounds. This latter drug is known not to cause or reverse iatrogenic SD. Most patients, after treatment with vortioxetine and/or nutraceuticals, reported a significant improvement in all International Index of Erectile Function-(IIEF-5) domains (p < 0.05) from baseline (T0) to 12-month follow-up (T1). Moreover, the only patient treated with pelvic muscle vibration reached very positive results. Although our data come from a retrospective open-label study with a small sample size, drugs positively modulating the central nervous system serotonin/dopamine ratio, such as vortioxetine, could be used to potentially improve PSSD. Large-sample prospective cohort studies and randomized clinical trials are needed to investigate the real prevalence of this clinical entity and confirm such a promising approach to a potentially debilitating illness.
Site-Differentiated Iron–Sulfur Cluster Ligation Affects Flavin-Based Electron Bifurcation Activity
Authors: Wise Courtney E. , Ledinina Anastasia E. , Lubner Carolyn E.
Published: September 2022

Electron bifurcation is an elegant mechanism of biological energy conversion that effectively couples three different physiologically relevant substrates. As such, enzymes that perform this function often play critical roles in modulating cellular redox metabolism. One such enzyme is NADH-dependent reduced-ferredoxin: NADP+ oxidoreductase (NfnSL), which couples the thermodynamically favorable reduction of NAD+ to drive the unfavorable reduction of ferredoxin from NADPH. The interaction of NfnSL with its substrates is constrained to strict stoichiometric conditions, which ensures minimal energy losses from non-productive intramolecular electron transfer reactions. However, the determinants for this are not well understood. One curious feature of NfnSL is that both initial acceptors of bifurcated electrons are unique iron–sulfur (FeS) clusters containing one non-cysteinyl ligand each. The biochemical impact and mechanistic roles of site-differentiated FeS ligands are enigmatic, despite their incidence in many redox active enzymes. Herein, we describe the biochemical study of wild-type NfnSL and a variant in which one of the site-differentiated ligands has been replaced with a cysteine. Results of dye-based steady-state kinetics experiments, substrate-binding measurements, biochemical activity assays, and assessments of electron distribution across the enzyme indicate that this site-differentiated ligand in NfnSL plays a role in maintaining fidelity of the coordinated reactions performed by the two electron transfer pathways. Given the commonality of these cofactors, our findings have broad implications beyond electron bifurcation and mechanistic biochemistry and may inform on means of modulating the redox balance of the cell for targeted metabolic engineering approaches.
All-MEMS Lidar Using Hybrid Optical Architecture with Digital Micromirror Devices and a 2D-MEMS Mirror
Authors: Kang Eunmo , Choi Heejoo , Hellman Brandon , Rodriguez Joshua , Smith Braden , Deng Xianyue , Liu Parker , Lee Ted , Evans Eric , Hong Yifan , Guan Jiafan , Luo Chuan , Takashima Yuzuru
Published: September 2022

In a lidar system, replacing moving components with solid-state devices is highly anticipated to make a reliable and compact lidar system, provided that a substantially large beam area with a large angular extent as well as high angular resolution is assured for the lidar transmitter and receiver. A new quasi-solid-state lidar optical architecture employs a transmitter with a two-dimensional MEMS mirror for fine beam steering at a fraction of the degree of the angular resolution and is combined with a digital micromirror device for wide FOV scanning over 37 degree while sustaining a large aperture area of 140 mm squared. In the receiver, a second digital micromirror device is synchronized to the transmitter DMD, which enables a large FOV receiver. An angular resolution of 0.57°(H) by 0.23° (V) was achieved with 0.588 fps for scanning 1344 points within the field of view.
Editorial for the Special Issue on Recent Advances in Thin Film Electronic Devices
Authors: Dong Chengyuan
Published: September 2022

Thin film electronic devices have been attracting more and more attention because of their applications in many industry fields, such as in flat panel displays (FPDs), energy devices, sensors, memories, and so on [...]
Efficiency Optimization of the Electroerosive Process in µ-WEDM of Steel MS1 Sintered Using DMLS Technology
Authors: Straka Ľuboslav , Gombár Miroslav , Vagaská Alena , Kuchta Patrik
Published: September 2022

Although the application of mathematical optimization methods for controlling machining processes has been the subject of much research, the situation is different for µ-WEDM. This fact has prompted us to fill the gap in this field in conjunction with investigating µ-WEDM’s very low productivity and overall process efficiency, since the current trend is oriented towards achieving high quality of the machined area at a high manufacturing productivity. This paper discusses in detail the application of non-linear programming (NLP) methods using MATLAB to maximize the process performance of µ-WEDM maraging steel MS1 sintered using direct metal laser sintering (DMLS) technology. The novelty of the solution lies mainly in the selection of efficient approaches to determine the optimization maximum on the basis of a solution strategy based on multi-factor analysis. The main contribution of this paper is the obtained mathematical-statistical computational (MSC) model for predicting high productivity and quality of the machined area with respect to the the optimal efficiency of the electrical discharge process in the µ-WEDM of maraging steel MS1 material. During the experimental research and subsequent statistical processing of the measured data, a local maximum of 0.159 mm3·min−1 for the MRR parameter and a local minimum of 1.051 µm for the Rz parameter were identified simultaneously during µ-WEDM maraging steel MS1, which was in the range of the predicted optimal settings of the main technological parameters (MTP).