bluuebunny/crossref_metadata_2025 huggingface dataset:
Fragility Assessment of RC Bridges Exposed to Seismic Loads and Corrosion over Time
Authors: Herrera Daniel , Tolentino Dante
Published: January 2023

A methodology to estimate the structural fragility of RC bridges, considering the effects of seismic loadings and corrosion over time, is presented. Two scenarios are considered: (a) The structure is exposed only to seismic loads, (b) Both the effect of corrosion and seismic loads are present in the system. The uncertainties related to material properties, structural geometry, seismic occurrences, corrosion initiation time, cracking and corrosion evolution are considered. Different time stages, such as 0, 50, 75, 100, and 125 years are selected to evaluate the effect of both seismic loads and seismic loads plus corrosion. The calculation of fragility curves implies a structural design, nonlinear modeling of structures with simulated properties, estimation of both corrosion times and seismic occurrences, and evaluation of structural demand over time considering the effect of seismic loads and corrosion. An illustrative example is provided on an RC continuous bridge with AASHTO beams, cap beams and circular columns located in Acapulco, Guerrero, Mexico. A performance level equal to 0.002 is chosen for the design of the structure. Results show that the probability of exceeding the design performance levels for both cases (seismic and seismic plus corrosion) are similar at the stage of time equal to zero (a newly built bridge). However, such probabilities, after 150 years, are equal to 0.61 and 0.85 due to the cumulative damage caused by seismic and seismic plus corrosion, respectively. The estimation of the probability of exceeding a certain performance level, considering the effect of corrosion together with seismic loads, highlights the importance of considering more than one type of solicitation for these kinds of structural systems. Lastly, recommendations about design are given.
The Relevance of Building an Appropriate Environment around an Atomic Resolution Transmission Electron Microscope as Prerequisite for Reliable Quantitative Experiments: It Should Be Obvious, but It Is a Subtle Never-Ending Story!
Authors: Taurino Antonietta , Carlino Elvio
Published: January 2023

The realization of electron microscopy facilities all over the world has experienced a paramount increase in the last decades. This means huge investments of public and private money due to the high costs of equipment, but also for maintenance and running costs. The proper design of a transmission electron microscopy facility is mandatory to fully use the advanced performances of modern equipment, capable of atomic resolution imaging and spectroscopies, and it is a prerequisite to conceive new methodologies for future advances of the knowledge. Nonetheless, even today, in too many cases around the world, the realization of the environment hosting the equipment is not appropriate and negatively influences the scientific quality of the results during the life of the infrastructure, practically vanishing the investment made. In this study, the key issues related to the realization of an advanced electron microscopy infrastructure are analyzed based on personal experience of more than thirty years, and on the literature.
Mathematical Model for Estimating the Sound Absorption Coefficient in Grid Network Structures
Authors: Satoh Takamasa , Sakamoto Shuichi , Isobe Takunari , Iizuka Kenta , Tasaki Kastsuhiko
Published: January 2023

Although grid network structures are often not necessarily intended to absorb sound, the gaps between the rods that make up the grid network are expected to have a sound absorption effect. In this study, the one-dimensional transfer matrix method was used to develop a simple mathematical model for accurately estimating the sound absorption coefficient of a grid network structure. The gaps in the grid network structure were approximated as the clearance between two parallel planes, and analysis units were derived to consider the exact geometry of the layers. The characteristic impedance and propagation constant were determined for the approximated gaps and treated as a one-dimensional transfer matrix. The transfer matrix obtained for each layer was used to calculate the sound absorption coefficient. The samples were fabricated from light-curing resin by using a Form2 3D printer from Formlabs. The measurement results showed that a sound absorption coefficient of 0.81 was obtained at the peak when seven layers were stacked. A sensitivity analysis was carried out to investigate the influence of the rod diameter and pitch. The simulated values tended to be close to the experimental values. The above results indicate that the mathematical model used to calculate the sound absorption coefficient is sufficiently accurate to predict the sound absorption coefficient for practical application.
Predicting Flexible Pavement Distress and IRI Considering Subgrade Resilient Modulus of Fine-Grained Soils Using MEPDG
Authors: Islam Kazi Moinul , Gassman Sarah L.
Published: January 2023

This paper highlights the subgrade resilient modulus (MR), which is recognized as an important parameter to characterize the stiffness of the subgrade soil for designing flexible pavement. In this study, 18 thin-walled Shelby tube samples of fine-grained subgrade soils were collected from two sites in South Carolina (Laurens/SC-72 and Pickens/SC-93) and tested in the laboratory using AASHTO T307-99 to obtain the MR. In addition, falling weight deflectometer (FWD) tests were performed on the same pavement sections to obtain the back-calculated MR(FWD) per the AASHTOWare 2017 back-calculation tool. A subgrade MR catalog was established and used to select hierarchical Input Level 2 for Pavement Mechanistic-Empirical design (PMED) analysis (v 2.6.1). The PMED analysis was run for 20 years. The Mechanistic-Empirical Pavement Design Guide (MEPDG) and global calibration values were used to predict asphalt concrete (AC) pavement distresses (e.g., rutting, bottom-up fatigue, top-down fatigue, and transverse cracking) and International Roughness Index (IRI) for each pavement section. The predicted values were compared to the field-measured values to determine bias and the standard error of the estimate to validate each distress prediction model for local calibration.
Band Structure, Phonon Spectrum and Thermoelectric Properties of Ag3CuS2
Authors: Pshenay-Severin Dmitry , Guin Satya Narayan , Konstantinov Petr , Novikov Sergey , Rathore Ekashmi , Biswas Kanishka , Burkov Alexander
Published: January 2023

Sulfides and selenides of copper and silver have been intensively studied, particularly as potentially efficient thermoelectrics. Ag3CuS2 (jalpaite) is a related material. However very little is known about its physical properties. It has been found that the compound undergoes several structural phase transitions, having the tetrahedral structural modification I41/amd at room temperature. In this work, its band structure, phonon spectrum and thermoelectric properties were studied theoretically and experimentally. Seebeck coefficient, electrical conductivity and thermal conductivity were measured in a broad temperature range from room temperature to 600 K. These are the first experimental data on transport properties of jalpaite. Ab initio calculations of the band structure and Seebeck coefficient were carried out taking into account energy dependence of the relaxation time typical for the scattering of charge carriers by phonons. The results of the calculations qualitatively agree with the experiment and yield large values of the Seebeck coefficient characteristic for lightly doped semiconductor. The influence of intrinsic defects (vacancies) on the transport properties was studied. It was shown that the formation of silver vacancies is the most probable and leads to an increase of hole concentration. Using the temperature dependent effective potential method, the phonon spectrum and thermal conductivity at room temperature were calculated. The measurements yield low lattice thermal conductivity value of 0.5 W/(m K) at 300 K, which is associated with the complex crystal structure of the material. The calculated room temperature values of the lattice thermal conductivity were also small (0.14–0.2 W/(m K)).
MXene-Based Nanomaterials for Multifunctional Applications
Authors: Perera A.A.P.R. , Madhushani K.A.U. , Punchihewa Buwanila T. , Kumar Anuj , Gupta Ram K.
Published: January 2023

MXene is becoming a “rising star” material due to its versatility for a wide portfolio of applications, including electrochemical energy storage devices, electrocatalysis, sensors, biomedical applications, membranes, flexible and wearable devices, etc. As these applications promote increased interest in MXene research, summarizing the latest findings on this family of materials will help inform the scientific community. In this review, we first discuss the rapid evolutionary change in MXenes from the first reported M2XTx structure to the last reported M5X4Tx structure. The use of systematically modified synthesis routes, such as foreign atom intercalation, tuning precursor chemistry, etc., will be further discussed in the next section. Then, we review the applications of MXenes and their composites/hybrids for rapidly growing applications such as batteries, supercapacitors, electrocatalysts, sensors, biomedical, electromagnetic interference shielding, membranes, and flexible and wearable devices. More importantly, we notice that its excellent metallic conductivity with its hydrophilic nature distinguishes MXene from other materials, and its properties and applications can be further modified by surface functionalization. MXene composites/hybrids outperform pristine MXenes in many applications. In addition, a summary of the latest findings using MXene-based materials to overcome application-specific drawbacks is provided in the last few sections. We hope that the information provided in this review will help integrate lab-scale findings into commercially viable products.
Study on Microstructure and Mechanical Properties of TC4/AZ31 Magnesium Matrix Nanocomposites
Authors: Chen Yong , Yao Yuan , Han Shengli , Feng Xiaowei , Luo Tiegang , Zheng Kaihong
Published: January 2023

In the field of metal matrix composites, it is a great challenge to improve the strength and elongation of magnesium matrix composites simultaneously. In this work, xTC4/AZ31 (x = 0.5, 1, 1.5 wt.%) composites were fabricated by spark plasma sintering (SPS) followed by hot extrusion. Scanning electron microscopy (SEM) showed that nano-TC4 (Ti-6Al-4V) was well dispersed in the AZ31 matrix. We studied the microstructure evolution and tensile properties of the composites, and analyzed the strengthening mechanism of nano-TC4 on magnesium matrix composites. The results showed that magnesium matrix composites with 1 wt.%TC4 had good comprehensive properties; compared with the AZ31 matrix, the yield strength (YS) was increased by 20.4%, from 162 MPa to 195 MPa; the ultimate tensile strength (UTS) was increased by 11.7%, from 274 MPa to 306 MPa, and the failure strain (FS) was increased by 21.1%, from 7.6% to 9.2%. The improvement in strength was mainly due to grain refinement and good interfacial bonding between nano-TC4 and the Mg matrix. The increase in elongation was the result of grain refinement and a weakened texture.
Launching Plasmons in a Two-Dimensional Material Traversed by a Fast Charged Particle
Authors: Marks Gareth Arturo , Blankespoor Devin , Miskovic Zoran L.
Published: January 2023

We use a dielectric-response formalism to compute the induced charge density and the induced potential in a conductive two-dimensional (2D) material, traversed by a charged particle that moves on a perpendicular trajectory with constant velocity. By analyzing the electric force on the material via the Maxwell stress tensor, we showed that the polarization of the material can be decomposed into a conservative part related to the dynamic image force, and a dissipative part describing the energy and momentum transfer to the material, which is ultimately responsible for launching the plasma oscillation waves in the material. After showing that the launching dynamics is fully determined by the Loss function of the material, we used a conductivity model suitable for the terahertz to the midinfrared frequency range, which includes both the intraband and interband electron transitions in the material, to compute the real-space and time animations of the propagating plasma waves in the plane of the material. Finally, we used a stationary phase analysis to show that the plasmon wave crests go into an overdamped regime at large propagation distances, which are comparable to the distances where retardation effects are expected to emerge due to hybridization of the plasmon dispersion with the light line at long wavelengths.
Phenolic Compounds Removal from Olive Mill Wastewater Using the Composite of Activated Carbon and Copper-Based Metal-Organic Framework
Authors: Abu-Dalo Muna A. , Al-Rawashdeh Nathir A. F. , Almurabi Moath , Abdelnabi Jehad , Al Bawab Abeer
Published: January 2023

As the industry of olive oil continues to grow, the management of olive mill wastewater (OMW) by-products has become an area of great interest. While many strategies for processing OMW have been established, more studies are still required to find an effective adsorbent for total phenolic content uptake. Here, we present a composite of a Cu 1,4-benzene dicarboxylate metal-organic framework (Cu (BDC) MOF) and granular activated carbon (GAC) as an adsorbent for total phenolic content removal from OMW. Experimental results demonstrated that the maximum adsorption capacity was 20 mg/g of total phenolic content (TPC) after 4 h. using 2% wt/wt of GAC/Cu (BDC) MOF composite to OMW at optimum conditions (pH of 4.0 and 25 °C). The adsorption of phenolic content onto the GAC/Cu (BDC) MOF composite was described by the Freundlich adsorption and pseudo-second-order reaction. The adsorption reaction was found to be spontaneous and endothermic at 298 K where ΔS° and ΔH° were found to be 0.105 KJ/mol and 25.7 kJ/mol, respectively. While ΔGº value was −5.74 (kJ/mol). The results of this study provide a potential solution for the local and worldwide olive oil industry.
Characterization of Dual-Layer Hybrid Biomatrix for Future Use in Cutaneous Wound Healing
Authors: Zulkiflee Izzat , Amirrah Ibrahim N. , Fadilah Nur Izzah Md , Wee M. F. Mohd Razip , Yusop Salma Mohamad , Maarof Manira , Fauzi Mh Busra
Published: January 2023

A skin wound without immediate treatment could delay wound healing and may lead to death after severe infection (sepsis). Any interruption or inappropriate normal wound healing, mainly in these wounds, commonly resulted in prolonged and excessive skin contraction. Contraction is a common mechanism in wound healing phases and contributes 40–80% of the original wound size post-healing. Even though it is essential to accelerate wound healing, it also simultaneously limits movement, mainly in the joint area. In the worst-case scenario, prolonged contraction could lead to disfigurement and loss of tissue function. This study aimed to fabricate and characterise the elastin-fortified gelatin/polyvinyl alcohol (PVA) film layered on top of a collagen sponge as a bilayer hybrid biomatrix. Briefly, the combination of halal-based gelatin (4% (w/v)) and PVA ((4% (w/v)) was used to fabricate composite film, followed by the integration of poultry elastin (0.25 mg/mL) and 0.1% (w/v) genipin crosslinking. Furthermore, further analysis was conducted on the composite bilayer biomatrix’s physicochemical and mechanical strength. The bilayer biomatrix demonstrated a slow biodegradation rate (0.374967 ± 0.031 mg/h), adequate water absorption (1078.734 ± 42.33%), reasonable water vapour transmission rate (WVTR) (724.6467 ± 70.69 g/m2 h) and porous (102.5944 ± 28.21%). The bilayer biomatrix also exhibited an excellent crosslinking degree and was mechanically robust. Besides, the elastin releasing study presented an acceptable rate post-integration with hybrid biomatrix. Therefore, the ready-to-use bilayer biomatrix will benefit therapeutic effects as an alternative treatment for future diabetic skin wound management.
Two-Step Preparation of CCF/PEEK Wrapped Yarn for 3D Printing Composites with Enhanced Mechanical Properties
Authors: Zhang Jianghu , Shen Hao , Yang Lili , Ge Dengteng
Published: January 2023

Continuous fiber reinforced thermoplastic composites (CFTPCs) have shown advantages such as high strength, long life, corrosion resistance, and green recyclability. Three-dimensional printing of CFTPCs opened up a new strategy for the fabrication of composites with complicated structures, low cost, and short production cycles. However, a traditional 3D printing process usually causes poor impregnation of the fiber or surface damage of the fiber due to the short impregnation time or high viscosity of the thermoplastic resin. Here, continuous carbon fiber/poly(ether-ether-ketones) (CCF/PEEK) wrapped yarn was fabricated via powder impregnation and using double spinning technology for the 3D printing. The concentration of PEEK powder suspension and wire speed were optimized as 15% and 2.0 m/min. The twist of wrapped yarn was optimized as 1037 T/m. Mechanical testing showed that the 3D-printed composite wire had excellent tensile and bending strength, which was about 1.6~4.2 times larger than those without the powder pre-impregnation process. It is mainly attributed to the improved impregnation of the CF which took place during the powder pre-impregnation process. We believe that our research on wrapped yarn for 3D-printed composites provides an effective strategy for the 3D printing of composites with enhanced mechanical properties.
MoS2/Au Heterojunction Catalyst for SERS Monitoring of a Fenton-like Reaction
Authors: Wei Qian , Lu Beibei , Yang Qing , Shi Can , Wei Yulan , Xu Minmin , Zhang Chenjie , Yuan Yaxian
Published: January 2023

Fenton technology is one of advanced oxidation process (AOP) methods to treat wastewater through chemical oxidation. Due to the limitations of classical iron-based catalysts, it is still challenging to find suitable catalysts for Fenton-like reactions. Here, MoS2/Au heterojunctions were successfully synthesized by reduction of chloroauric acid in the solution of layered MoS2 prepared by hydrothermal method. As a model molecule, methylene blue (MB) was used as the species to be degraded to evaluate the performance of the catalyst. It was determined by UV–visible spectra that the optimal catalyst can be obtained when MoS2 (mg): HAuCl4 (wt. % mL) is 2:2. The Fenton-like reaction process was monitored by introducing highly sensitive surface enhanced Raman spectroscopy (SERS). The results show that MB can be degraded by 83% in the first 10 min of the reaction, indicating that MoS2/Au has good catalytic performance. In addition, as a fingerprint spectrum, SERS was used to preliminarily analyze the molecular structure changes during the degradation process. The result showed that C-N-C bond was easier to break than the C-S-C bond. NH2 group and the fused ring were destroyed at the comparable speed at the first 30 min. In terms of application applicability, it was showed that MB degradation had exceeded 95% at all the three pH values of 1.4, 5.0, and 11.1 after the reaction was carried out for 20 min. The test and analysis of the light environment showed that the catalytic efficiency was significantly improved in the natural light of the laboratory compared to dark conditions. The possible mechanism based on ·OH and ·O2− from ESR data was proposed. In addition, it was demonstrated to be a first-order reaction from the perspective of kinetics. This study made a positive contribution to broaden of the applicable conditions and scope of Fenton-like reaction catalysts. It is expected to be used as a non-iron catalyst in practical industrial applications. From the perspective of detection method, we expect to develop SERS as a powerful tool for the in situ monitoring of Fenton-like reactions, and to further deepen our understanding of the mechanism.
A Central Spiral Split Rectangular-Shaped Metamaterial Absorber Surrounded by Polarization-Insensitive Ring Resonator for S-Band Applications
Authors: Sakib Shihabun , Hoque Ahasanul , Rahim Sharul Kamal Bin Abdul , Singh Mandeep , Sahar Norsuzlin Mohd , Islam Md. Shabiul , Soliman Mohamed S. , Islam Mohammad Tariqul
Published: January 2023

This paper reports a central spiral split-rectangular-shaped metamaterial absorber surrounded by a polarization-insensitive ring resonator for s-band applications. The rated absorption is 99.9% at 3.1 GHz when using a three-layer structure where the top and ground are made of copper and the center dielectric material is a commonly used FR-4 substrate. The central split gaps have an impact on the unit cell by increasing high absorption, and an adequate electric field is apparent in the outer split ring gap. At 3.1 GHz, the permittivity and permeability are negative and positive, respectively, so the proposed unit cell acts as an epsilon negative (ENG) metamaterial absorber. In a further analysis, Roger4450B was used as a substrate and obtained excellent absorption rates of 99.382%, 99.383%, 99.91%, and 95.17% at 1.44, 3.96, 4.205, and 5.025 GHz, respectively, in the S- and C-band regions. This unit cell acts as a single negative metamaterial (SNG) absorber at all resonance frequencies. The S11 and S21 parameters for FR-4 and Rogers4450B were simulated while keeping the polarization angle (θ and φ) at 15, 30, 45, 60, 75, and 90 degrees to measure, permittivity, permeability, reflective index, absorption, and reflection. The values of the reflective index are near zero. Near-zero reflective indexes (NZRI) are widely used in antenna gain propagation. The unit cell fabricated for the FR-4 substrate attained 99.9% absorption. S-band values in the range of (2–4) GHz can be applied for low-frequency radar detection.
A Trilinear Model for the Load–Slip Behavior of Headed Stud Shear Connectors
Authors: Meng Hao , Wang Wei , Xu Rongqiao
Published: January 2023

Headed stud shear connectors are most broadly applied in various composite structures. There exist plenty of empirical formulae for load–slip curves. However, most of them are fitting formulae in particular forms. Due to the lack of physical model support, fitting empirical formulae apply only to cases with similar parameters to the tests. Therefore, this paper analyzes the load–slip curves of existing headed stud connectors, proposes three stages of slip deformation in the shear connectors and the corresponding trilinear model, and presents the analytical formulae for the stiffness and strength of headed stud shear connectors. Firstly, we model the headed studs and surrounding concrete as beams on the foundation model, derive the equivalent shear stiffness equations for headed studs, and establish the load–slip behaviors for the first two stages. Then, the connectors’ shear stiffness and shear strength in the third stage are derived based on the head stud’s plastic deformation characteristics and failure mode. Finally, the numerical results are presented and verified with the existing test results, showing that the trilinear model is conceptually straightforward, easy to apply, and has sufficient accuracy.
Reinforcement Corrosion Testing in Concrete and Fiber Reinforced Concrete Specimens Exposed to Aggressive External Factors
Authors: Raczkiewicz Wioletta , Bacharz Magdalena , Bacharz Kamil , Teodorczyk Michał
Published: January 2023

One of the leading causes of reinforced concrete degradation is chloride attack. It occurs due to the penetration of chlorides through pores and cracks into the concrete cover. This phenomenon becomes more dangerous if reinforced concrete elements are subjected to cyclic temperature changes. The concrete cover protects against corrosion. This paper presents research, the primary purpose of which was to determine the effect of the addition of steel fibers to concrete on the development of corrosion of the main reinforcement. The tests were carried out on three types of reinforced concrete specimens made of ordinary concrete and concrete with different amounts of steel fibers (0.25% and 0.50%). In order to initiate corrosion processes, specimens were partially submerged in a 3% sodium chloride solution and were subjected to freeze–thaw cycles. The electrochemical polarization galvanostatic pulse method was used for analyzing the reinforcement corrosion activity. Moreover, it was verified whether the corrosion of reinforced concrete elements affects the acoustic emission wave velocity. The addition of steel micro-reinforcement fibers increases the corrosion resistance of reinforced concrete. In addition, a strong linear correlation between the AE wave velocity and the values of the corrosion current density was revealed.
The Effect of Copper on the Microstructure, Wear and Corrosion Resistance of CoCrCuFeNi High-Entropy Alloys Manufactured by Powder Metallurgy
Authors: Mukanov Samat , Loginov Pavel , Fedotov Alexander , Bychkova Marina , Antonyuk Maria , Levashov Evgeny
Published: January 2023

This paper focuses on the microstructure, phase composition, mechanical, tribological and corrosion properties of high-entropy alloys (HEAs) in the CoCrCuFeNi system depending on copper content, which was varied from 0 to 20 at. % with an increment of 5%. CoCrCuFeNi alloys were manufactured by powder metallurgy methods: mechanical alloying and hot pressing of element mixtures. The solubility limit of copper in CoCrFeNi solid solution was found to be 9 at. %. Segregation of irregularly shaped copper grains sized 1–30 μm is observed at concentrations above this solubility limit. As copper concentration increases, the phase composition of CoCrCuFeNi alloys changes from the single phase based on FCC1 solid solution (Cu = 0–5 at. %) to the dual-phase FCC1 + FCC2 alloy (Cu = 10–20 at. %), where FCC1 is the main phase and FCC2 is the secondary copper-rich phase. Tribological tests have shown that doping the CoCrFeNi alloy with copper increased wear resistance by 23% due to solid solution hardening. As copper content rises above 20%, the content of the secondary FCC2 phase increases, while wear resistance and alloy hardness decline. An analysis of wear tracks and wear products has shown that abrasion of CoCrCuFeNi alloys occurs via the abrasive-oxidative wear mechanism. The corrosion tests of CoCrCuFeNi HEAs in 3.5% NaCl solution had demonstrated that doping the alloy with copper at low concentrations (5–10%) leads to decreasing of corrosion resistance, possibly due to the formation of undesirable oxide Cu2O along with protective Cr2O3. At high copper concentrations (15–20%) galvanic corrosion is suppressed due to coarsening of FCC2 grains and thus decreasing the specific contact surface area between the cathode (FCC2) and the anode (FCC1).
Oxidation Kinetics of Ti-6Al-4V Alloys by Conventional and Electron Beam Additive Manufacturing
Authors: Estupinán-López Francisco , Orquiz-Muela Carlos , Gaona-Tiburcio Citlalli , Cabral-Miramontes Jose , Bautista-Margulis Raul German , Nieves-Mendoza Demetrio , Maldonado-Bandala Erick , Almeraya-Calderón Facundo , Lopes Amit Joe
Published: January 2023

New manufacturing processes for metal parts such as additive manufacturing (AM) provide a technological development for the aeronautical and aerospace industries, since these AM processes are a means to reduce the weight of the parts, which generate cost savings. AM techniques such as Laser Powder Bed Fusions (LPBF) and Electron Beam Fusion (EBM), provided an improvement in mechanical properties, corrosion resistance, and thermal stability at temperatures below 400 °C, in comparison to conventional methods. This research aimed to study the oxidation kinetics of Ti-6Al-4V alloys by conventional and Electron Beam Additive Manufacturing. The thermogravimetric analysis was performed at temperatures of 600 °C, 800 °C, and 900 °C, having a heating rate of 25 °C/min and oxidation time of 24 h. The microstructural analysis was carried out by thermogravimetric analysis. Thickness and morphology of oxide layers were analyzed by field emission scanning electron microscope, phase identification (before and after the oxidation process) was realized by X-ray diffraction at room temperature and hardness measurements were made in cross section. Results indicated that the oxidation kinetics of Ti-6Al-4V alloys fabricated by EBM was similar to conventional processing and obeyed a parabolic or quasi-parabolic kinetics. The samples oxidized at 600 °C for 24 h presented the lowest hardness values (from 350 to 470 HV). At oxidation temperatures of 800 and 900 °C, however, highest hardness values (from 870 close to the alpha-case interface up to 300 HV in base metal) were found on the surface and gradually decreased towards the center of the base alloy. This may be explained by different microstructures presented in the manufacturing processes.
Flame Synthesis of Carbon and Metal-Oxide Nanoparticles: Flame Types, Effects of Combustion Parameters on Properties and Measurement Methods
Authors: Serrano-Bayona Raul , Chu Carson , Liu Peng , Roberts William L.
Published: January 2023

Carbon and metal-oxide nanoparticles (NP) are currently synthesized worldwide for various applications in the solar-energy, optical, pharmaceutical, and biomedical industries, among many others. Gas phase methods comprise flame synthesis and flame spray pyrolysis (FSP), which provide high efficiency, low cost, and the possibility of large-scale applications. The variation of combustion operation parameters exerts significant effects on the properties of the NPs. An analysis of the latest research results relevant to NP flame synthesis can provide new insight into the optimization of these methods and the development of these techniques for a large scale. This review offers insight into the current status of flame synthesis for carbon and metal-oxide NPs—specifically containing analysis and comparison of the most common carbon and metal-oxide NP production techniques. The burner configurations used at the laboratory scale and large scale are also discussed, followed by the assessment of the influence of combustion parameters on the properties of NPs. Finally, the features of the measurement techniques applied for determining NP properties were described.
Runtime Verification for Anomaly Detection of Robotic Systems Security
Authors: Kirca Yunus Sabri , Degirmenci Elif , Demirci Zekeriyya , Yazici Ahmet , Ozkan Metin , Ergun Salih , Kanak Alper
Published: January 2023

Robotic systems are widely used in industry, agriculture, the inspection of infrastructure, and even in our daily lives. The safety and security of robotic systems have become a primary concern as their interaction with humans increases. In this context, attacks on robotic systems have increased for diversified field applications. It is necessary to accurately detect these abnormal events in these systems as soon as possible. However, these systems also need a runtime verification approach on whether they conform to the established specifications. In this study, runtime verification for anomaly detection methods is proposed for the security of the robot operating system (ROS). Firstly, an anomaly detection method is proposed to detect unexpected situations, such as the number of the received packages being decreased under DoS attacks. Then, a holistic runtime verification architecture is proposed for the anomaly detection method. This architecture consists of three major entities: a verification device, an attacker device, and a robotic platform without losing generality. In the verification device, ROSMonitoring and Oracle are used to implement runtime verification. The proposed architecture is verified through an experimental setup. It is shown that the architecture can be used for runtime verification of different anomaly detection algorithms. A discussion on the security of robotic systems is also presented.
On the Use of a Genetic Algorithm for Determining Ho–Cook Coefficients in Continuous Path Planning of Industrial Robotic Manipulators
Authors: Grenko Teodor , Baressi Šegota Sandi , Anđelić Nikola , Lorencin Ivan , Štifanić Daniel , Štifanić Jelena , Glučina Matko , Franović Borna , Car Zlatan
Published: January 2023

Path planning is one of the key steps in the application of industrial robotic manipulators. The process of determining trajectories can be time-intensive and mathematically complex, which raises the complexity and error proneness of this task. For these reasons, the authors tested the application of a genetic algorithm (GA) on the problem of continuous path planning based on the Ho–Cook method. The generation of trajectories was optimized with regard to the distance between individual segments. A boundary condition was set regarding the minimal values that the trajectory parameters can be set in order to avoid stationary solutions. Any distances between segments introduced by this condition were addressed with Bezier spline interpolation applied between evolved segments. The developed algorithm was shown to generate trajectories and can easily be applied for the further path planning of various robotic manipulators, which indicates great promise for the use of such algorithms.
Automated Fire Extinguishing System Using a Deep Learning Based Framework
Authors: Jagatheesaperumal Senthil Kumar , Muhammad Khan , Saudagar Abdul Khader Jilani , Rodrigues Joel J. P. C.
Published: January 2023

Fire accidents occur in every part of the world and cause a large number of casualties because of the risks involved in manually extinguishing the fire. In most cases, humans cannot detect and extinguish fire manually. Fire extinguishing robots with sophisticated functionalities are being rapidly developed nowadays, and most of these systems use fire sensors and detectors. However, they lack mechanisms for the early detection of fire, in case of casualties. To detect and prevent such fire accidents in its early stages, a deep learning-based automatic fire extinguishing mechanism was introduced in this work. Fire detection and human presence in fire locations were carried out using convolution neural networks (CNNs), configured to operate on the chosen fire dataset. For fire detection, a custom learning network was formed by tweaking the layer parameters of CNN for detecting fires with better accuracy. For human detection, Alex-net architecture was employed to detect the presence of humans in the fire accident zone. We experimented and analyzed the proposed model using various optimizers, activation functions, and learning rates, based on the accuracy and loss metrics generated for the chosen fire dataset. The best combination of neural network parameters was evaluated from the model configured with an Adam optimizer and softmax activation, driven with a learning rate of 0.001, providing better accuracy for the learning model. Finally, the experiments were tested using a mobile robotic system by configuring them in automatic and wireless control modes. In automatic mode, the robot was made to patrol around and monitor for fire casualties and fire accidents. It automatically extinguished the fire using the learned features triggered through the developed model.
Promising Antiparasitic Natural and Synthetic Products from Marine Invertebrates and Microorganisms
Authors: Zhang Mingyue , Zhang Qinrong , Zhang Qunde , Cui Xinyuan , Zhu Lifeng
Published: January 2023

Parasitic diseases still threaten human health. At present, a number of parasites have developed drug resistance, and it is urgent to find new and effective antiparasitic drugs. As a rich source of biological compounds, marine natural products have been increasingly screened as candidates for developing new antiparasitic drugs. The literature related to the study of the antigenic animal activity of marine natural compounds from invertebrates and microorganisms was selected to summarize the research progress of marine compounds and the structure–activity relationship of these compounds in the past five years and to explore the possible sources of potential antiparasitic drugs for parasite treatment.
Magnetic Hydroxyapatite Composite Nanoparticles for Augmented Differentiation of MC3T3-E1 Cells for Bone Tissue Engineering
Authors: Kaliannagounder Vignesh , Hossain Mohammad , Kim Jong-Hoon , Thangavelu Muthukumar , Adithan Aravinthan
Published: January 2023

Progressive aging harms bone tissue structure and function and, thus, requires effective therapies focusing on permanent tissue regeneration rather than partial cure, beginning with regenerative medicine. Due to advances in tissue engineering, stimulating osteogenesis with biomimetic nanoparticles to create a regenerative niche has gained attention for its efficacy and cost-effectiveness. In particular, hydroxyapatite (HAP, Ca10(PO4)6(OH)2) has gained significant interest in orthopedic applications as a major inorganic mineral of native bone. Recently, magnetic nanoparticles (MNPs) have also been noted for their multifunctional potential for hyperthermia, MRI contrast agents, drug delivery, and mechanosensitive receptor manipulation to induce cell differentiation, etc. Thus, the present study synthesizes HAP-decorated MNPs (MHAP NPs) via the wet chemical co-precipitation method. Synthesized MHAP NPs were evaluated against the preosteoblast MC3T3-E1 cells towards concentration-dependent cytotoxicity, proliferation, morphology staining, ROS generation, and osteogenic differentiation. The result evidenced that MHAP NPs concentration up to 10 µg/mL was non-toxic even with the time-dependent proliferation studies. As nanoparticle concentration increased, FACS apoptosis assay and ROS data showed a significant rise in apoptosis and ROS generation. The MC3T3-E1 cells cocultured with 5 µg/mL MHAP NPs showed significant osteogenic differentiation potential. Thus, MHAP NPs synthesized with simple wet chemistry could be employed in bone regenerative therapy.
Thermodynamic Study of H2-FeO Based on the Principle of Minimum Gibbs Free Energy
Authors: Chen Shuyue , Zhang Jianliang , Wang Yaozu , Wang Tengfei , Li Yang , Liu Zhengjian
Published: January 2023

Studies have shown that the reduction of wustite is the limiting factor in the ironmaking process, whether in hydrogen-based shaft furnaces, hydrogen-rich blast furnaces or smelting reduction vessels. The study of the thermodynamic conditions for the reduction of molten wustite by hydrogen is of great significance for the optimization of the ironmaking process, energy saving and emission reduction. Previous studies have mostly focused on the thermodynamic study of the reduction at a lower temperature, but the data at high temperatures are different, which makes the calculation of thermodynamics difficult. Moreover, it is difficult to obtain experimental evidence for the data at high temperature, so calculation is needed to verify its feasibility. In this paper, a thermodynamic calculation model for the reduction of molten wustite by hydrogen based on the principle of minimum Gibbs free energy is developed. The enthalpy changes of the reaction at different temperatures and the partial pressure of hydrogen required for the reaction to occur are calculated, and the energy change during the reaction is analyzed. The results show that the partial pressure of hydrogen for the reduction of molten wustite by hydrogen at high temperatures decreases from 0.67 at 1650 K to about 0.65 at 2000 K. The enthalpy changes of reaction at 1873 K are only 1/4 to 1/3 of that at 1173 K compared with that at the corresponding temperature between hydrogen for the reduction of molten wustite (1873 K) and hydrogen-based shaft furnace reaction (1173 K). Interestingly, the thermodynamic calculations show that the effect of energy absorption in the gas–liquid reaction of hydrogen with wustite at high temperatures is much lower than in the gas–solid reaction zone at low temperatures. These results indicate that the energy change of the reduction of molten wustite by hydrogen at high temperatures is better than that of hydrogen reduction at low temperatures, and the thermodynamic conditions are more favorable, with slightly different results from different thermodynamic databases, but the general trend is the same. The results of this study will provide fundamental data to support new hydrogen metallurgy technologies in the future. If its correctness can be verified experimentally in the future, this result will be promoted to the development of a new alternative ironmaking technology, hydrogen-based smelting reduction.
Study of Tensile Deformation and Damage Law in Undermatching X80 Pipeline Steel Welded Joints
Authors: Que Yongbin , Wu Yi , Wang Guanhua , Jia Haidong , Zhang Shichao , Feng Qingshan , Dai Lianshuang
Published: January 2023

This study used a digital imaging technique (DIC) to obtain the strain distribution at various locations in undermatching X80 pipe girth-weld joints under uniaxial tensile loading. In addition, the microstructure characteristics and deformation patterns in different regions were analyzed by scanning electron microscopy (SEM). The results showed that there was strain heterogeneity between the various regions of the welded joint. Strain concentration existed only in the 12.8 mm base metal heat-affected zone (HAZ) and only in the elastic deformation stage. There was strain concentration in the weld metal (WM) and both sides of the HAZ close to the near-fracture stage, and the maximum deformation was in the WM. When εM = 12.2%, the KC was 6.27 and the KF was 1.73, and the KF was 113% and 152% of the KC and the KG, respectively. The large number of slip strips generated indicated serious damage in the WM near the fracture stage. In the elastic deformation stage, the strain concentration of the N1 HAZ was caused by the softened ferrite. The maximum deformation of the WM near the fracture stage was caused by the large grain size and the non-uniform martensite–austenite (M–A) islands, which may also lead to better local toughness of the cover weld and further affect the fracture mechanism of the welded joint.
Investigation of Phospholipid Differences in Valproic Acid-Induced Autistic Mouse Model Brain Using Mass Spectrometry Imaging
Authors: Jang Hyun Jun , Kwon Kyoung Ja , Shin Chan Young , Lee Ga Seul , Moon Jeong Hee , Lee Tae Geol , Yoon Sohee
Published: January 2023

Autism is a neurodevelopmental disorder for which the cause and treatment have yet not been determined. The polyunsaturated fatty acid (PUFA) levels change rapidly in the blood or cerebrospinal fluid of autistic children and PUFAs are closely related to autism spectrum disorder (ASD). This finding suggests that changes in lipid metabolism are associated with ASD and result in an altered distribution of phospholipids in cell membranes. To further understand ASD, it is necessary to analyze phospholipids in organs consisting of nerve cells, such as the brain. In this study, we investigated the phospholipid distribution in the brain tissue of valproic acid-induced autistic mice using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Phospholipids including phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine were identified in each brain region and exhibited differences between the ASD and control groups. These phospholipids contain docosahexaenoic acid and arachidonic acid, which are important PUFAs for cell signaling and brain growth. We expect that the differences in phospholipids identified in the brain tissue of the ASD model with MALDI-MSI, in conjunction with conventional biological fluid analysis, will help to better understand changes in lipid metabolism in ASD.
Status and Prospects of Heterojunction-Based HEMT for Next-Generation Biosensors
Authors: Fauzi Najihah , Mohd Asri Rahil Izzati , Mohamed Omar Mohamad Faiz , Manaf Asrulnizam Abd , Kawarada Hiroshi , Falina Shaili , Syamsul Mohd
Published: January 2023

High electron mobility transistor (HEMT) biosensors hold great potential for realizing label-free, real-time, and direct detection. Owing to their unique properties of two-dimensional electron gas (2DEG), HEMT biosensors have the ability to amplify current changes pertinent to potential changes with the introduction of any biomolecules, making them highly surface charge sensitive. This review discusses the recent advances in the use of AlGaN/GaN and AlGaAs/GaAs HEMT as biosensors in the context of different gate architectures. We describe the fundamental mechanisms underlying their operational functions, giving insight into crucial experiments as well as the necessary analysis and validation of data. Surface functionalization and biorecognition integrated into the HEMT gate structures, including self-assembly strategies, are also presented in this review, with relevant and promising applications discussed for ultra-sensitive biosensors. Obstacles and opportunities for possible optimization are also surveyed. Conclusively, future prospects for further development and applications are discussed. This review is instructive for researchers who are new to this field as well as being informative for those who work in related fields.
Valorization of Banana Peel Using Carbonization: Potential Use in the Sustainable Manufacturing of Flexible Supercapacitors
Authors: Tadesse Melkie Getnet , Kasaw Esubalew , Lübben Jörn Felix
Published: January 2023

Sustainable and environmentally friendly activated carbon from biomass materials is proposed to produce supercapacitors from banana peels and has the potential to replace the non-sustainable and hazardous process from either graphite or/and fossil fuels. In order to determine the potential of using banana peel for supercapacitor application, raw banana peel, a bio-waste, was activated both mechanically and chemically to observe the real differences. The sample was activated at 700 °C and chemically activated using KOH. Characterization of activated banana peel was performed using FTIR, DLS, TGA and XRD analytical equipment. FTIR analysis revised the presence of hydroxyl, carbonyl and aromatic compounds on a banana peel cellulose-based carbon. The TGA results proved that 700 °C could be sufficient to totally carbonize banana peel. DLS clearly showed a strong difference between the carbonized and KOH-activated material in particle size distribution. Meanwhile, surface area analysis using BET displayed an increase from 553.862 m2/g to 565.024 m2/g BET in surface area (SBET) when carbon was activated using KOH with a nitrogen isotherm at 77.350 K. Specific capacitance was increased from 0.3997 Fg−1 to 0.821 Fg−1, suggesting more than a 100% increase in the specific capacity due to KOH activation, as proved by the cyclic voltammetry (CV) curve. The X-ray diffraction results revealed the patterns of activated carbon. The findings demonstrated the feasibility of using banana peel waste as a low-cost and sustainable material for the preparation of flexible supercapacitor batteries.
Analysis and Suppression of Crosstalk Stray Light in a Microlens Array Scanning and Searching System
Authors: Lv Zhiyang , Huang Yunhan , Liu Zhiying
Published: January 2023

The microlens array (MLA) system can aid in realizing fast beam deflection owing to the lateral displacement between arrays. The MLA system has the advantages of miniaturization and good functionality. However, during system operation, crosstalk beams are generated between each microlens array unit, introducing additional stray light, thus affecting the imaging contrast of the system. Therefore, this study uses the matrix operation method to trace the paraxial ray to trace the optical system and analyzes the generation mechanism of crosstalk stray light in the MLA system. Furthermore, this study proposes a crosstalk suppression method based on a stop array to reasonably suppress stray light. Finally, an example of an infrared array scanning infrared optical system is considered so as to verify the correctness and feasibility of the proposed crosstalk stray light suppression method. Therefore, this paper introduces the stray light suppression principle to guide the optical design process of the system, providing a theoretical basis for the design and analysis of the microlens array scanning and search system.