bluuebunny/crossref_metadata_2025 huggingface dataset:
Alloy Design and Fabrication of Duplex Titanium-Based Alloys by Spark Plasma Sintering for Biomedical Implant Applications
Authors: Ijaz Muhammad Farzik , Alharbi Hamad F. , Bahri Yassir A. , Sherif El-Sayed M.
Published: December 2022

Very often, pure Ti and (α + β) Ti-6Al-4V alloys have been used commercially for implant applications, but ensuring their chemical, mechanical, and biological biocompatibility is always a serious concern for sustaining the long-term efficacy of implants. Therefore, there has always been a great quest to explore new biomedical alloying systems that can offer substantial beneficial effects in tailoring a balance between the mechanical properties and biocompatibility of implantable medical devices. With a view to the mechanical performance, this study focused on designing a Ti-15Zr-2Ta-xSn (where x = 4, 6, 8) alloying system with high strength and low Young’s modulus prepared by a powder metallurgy method. The experimental results showed that mechanical alloying, followed by spark plasma sintering, produced a fully consolidated (α + β) Ti-Zr-Ta-Sn-based alloy with a fine grain size and a relative density greater than 99%. Nevertheless, the shape, size, and distribution of α-phase precipitations were found to be sensitive to Sn contents. The addition of Sn also increased the α/β transus temperature of the alloy. For example, as the Sn content was increased from 4 wt.% to 8 wt.%, the β grains transformed into diverse morphological characteristics, namely, a thin-grain-boundary α phase (αGB), lamellar α colonies, and acicular αs precipitates and very low residual porosity during subsequent cooling after the spark plasma sintering procedure, which is consistent with the relative density results. Among the prepared alloys, Ti-15Zr-2Ta-8Sn exhibited the highest hardness (s340 HV), compressive yield strength (~1056 MPa), and maximum compressive strength (~1470). The formation of intriguing precipitate–matrix interfaces (α/β) acting as dislocation barriers is proposed to be the main reason for the high strength of the Ti-15Zr-2Ta-8Sn alloy. Finally, based on mechanical and structural properties, it is envisaged that our developed alloys will be promising for indwelling implant applications.
Effects of Functionalized Materials and Bacterial Metabolites on Quality Indicators in Composts
Authors: Gondek Krzysztof , Micek Piotr , Mierzwa-Hersztek Monika , Kowal Jerzy , Andres Krzysztof , Szczurowska Katarzyna , Lis Marcin , Smoroń Krzysztof
Published: December 2022

The addition of functionalized materials (biochar, zeolite, and diatomite) and lyophilized metabolic products of Pseudomonas sp. and Bacillus subtilis to composted biomass may bring many technological and environmental benefits. In this study, we verify the effects of biochar, zeolite Na-P1 (Na6Si10Al6O32·12 H2O), diatomite (SiO2_nH2O), and bacterial metabolites on the composting of biomass prepared from poultry litter, corn straw, grass, leonardite, and brown coal. The experimental design included the following treatments: C—biomass without the addition of functionalized materials and bacterial metabolites, CB—biomass with the addition of biochar, CBM—biomass with the addition of biochar and bacterial metabolites, CZ—biomass with the addition of zeolite, CZM—biomass with the addition of zeolite and bacterial metabolites, CD—biomass with the addition of diatomite, and CDM—biomass with the addition of diatomite and bacterial metabolites. Composts were analyzed for enzymatic and respiratory activities, mobility of heavy metals, and the presence of parasites. The results of this study revealed that, among the analyzed functionalized materials, the addition of diatomite to the composted biomass (CD and CDM) resulted in the most effective immobilization of Cd, Zn, Pb, and Cu. Zinc immobilization factors (IFHM) for diatomite-amended composts averaged 30%. For copper, each functionalized material was found to enhance mobilization of the element in bioavailable forms; similar observations were made for lead, except for the compost to which biochar and bacterial metabolites were added (CBM). The determined values of biochemical indicators proved the different effects of the applied functionalized materials and bacterial metabolites on the microbial communities colonizing individual composts. The dehydrogenase activity (DhA) was lower in all combinations as compared with the control, indicating an intensification of the rate of processes in the studied composts. The highest basal respiration (BR) and substrate-induced respiration (SIR) activities were determined in composts with the addition of bacterial metabolites (CBM, CZM, and CDM). The addition of functionalized materials completely inactivated Eimeria sp. in all combinations. In the case of Capillaria sp., complete inactivation was recorded for the combination with zeolite as well as biochar and diatomite without bacterial metabolites (CB, CZ, and CD).
Effect of Isothermal Holding at 750 °C and 900 °C on Microstructure and Properties of Cast Duplex Stainless Steel Containing 24% Cr-5% Ni-2.5% Mo-2.5% Cu
Authors: Kalandyk Barbara Elżbieta , Zapała Renata Elżbieta , Pałka Paweł
Published: December 2022

Changes in the microstructure and selected mechanical properties of two-phase ferritic-austenitic cast steel containing 24% Cr-5% Ni-2.5% Mo-2.5% Cu after isothermal holding at 750 °C and 900 °C are presented. The choice of the two temperatures of isothermal holding was dictated by the precipitation of brittle phases within a range of 600 °C–950 °C, while the holding time depended on the casting cooling time in the mould. Changes in the microstructure were studied by the SEM-EDS and XRD techniques. As a result of the decomposition of the eutectoid ferrite, a σ phase that was rich in Cr, Mo, and Ni and a secondary γ2 austenite with Widmannstätten morphology were formed. Compared to the austenite, the chemical composition of the secondary γ2 austenite showed depletion of Cr and Mo. In the ferrite, the presence of Cr2N nitrides was also detected. After a holding time of 3 h at 900 °C, these phases increased the hardness of the tested cast steel to approximately 275 HV10. At the same time, the UTS value was recorded to decrease with the increasing temperature based on the tensile test results. At 750 °C, the value of UTS was 250 MPa for 1 h of holding and 345 MPa for 3 h of holding. These values decreased after increasing the temperature to 900 °C and amounted to 139 for 1 h holding and 127 MPa for 3 h holding. It was also found that the elongation values at 750 °C ranged from 7–10%, while they amounted to 35–37% at 900 °C. A fracture analysis of the tested cast steel showed that in the prevailing part, the fractures were made of ductile nature with an arrangement of dimples that is typical for this type of fracture. Non-metallic inclusions that are typical for cast steel (i.e., oxides and nitrides) were also found in the area of the fractures.
Study on the Influence of Delamination Damage on the Processing Quality of Composite Laminates
Authors: Yu Jiali , Shan Yimeng , Zhao Yiming , Mo Ran
Published: December 2022

Internal delamination damage in composite connection structures can occur in the process of the overloading of a high-speed bearing, with alternating force loads, high or low temperatures, and the humid or hot environment loads. Mechanical drilling and riveting are usually used at the delamination position and outside its envelope, to inhibit delamination expansion. However, delamination damage can change the structural stress state of the original structure. It is difficult to achieve a better inhibition effect using conventional drilling mechanisms and process methods with intact composite panels, and new damage forms can even be introduced into the drilling process due to unreasonable parameter settings. Therefore, this paper combined finite element simulation technology and experimental processing technology, to analyze the influence of different delamination dimensions and positions on processing quality. The results showed that the feed speed and rotating speed had significant effects on the axial force of composite laminates. In particular, in the case of a low speed and high feed, the axial force will increase significantly.
An Efficient High-Order-Moment-Based Reliability Method Combining the Maximum Likelihood Point and Cubic Normal Transformation
Authors: Cao Shuang , Lu Hao
Published: December 2022

Moment-based methods can measure the safety degrees of mechanical systems affected by unavoidable uncertainties, utilizing only the statistical moments of random variables for reliability analysis. For the conventional derivation of the first four statistical moments based on the second-order Taylor expansion series evaluated at the most likelihood point (MLP), skewness and kurtosis involve the higher fourth raw moments of random variables and thus are unfavorable for engineering applications. This paper develops new computing formulae for the first four statistical moments which require only the first four central moments of random variables, and the probability distribution of the performance function is approximated using cubic normal transformation. Several numerical examples are given to demonstrate the accuracy of the proposed methods. Comparisons of the two proposed approaches and the maximum entropy method (ME) are also made regarding reliability assessment.
Effect of ZrO2 Content on Microstructure Evolution and Sintering Properties of (Tb0.7Lu0.3)2O3 Magneto-Optic Transparent Ceramics
Authors: Xin Yu , Xu Tao , Wang Yaozhi , Luo Peng , Li Weiwei , Kang Bin , Mei Bingchu , Jing Wei
Published: December 2022

In this paper, (Tb0.7Lu0.3)2O3 magneto-optical transparent ceramics with different ZrO2 doping levels (0~5 at%) were prepared by hydrogen sintering and sequential HIP technique using ZrO2 as a sintering aid. The effect of ZrO2 doping content on the microstructure and optical properties of (Tb0.7Lu0.3)2O3 ceramics was analyzed. We found that the optimal doping content of ZrO2 was 3 at%. The transmittance of 3 at% ZrO2-doped (Tb0.7Lu0.3)2O3 ceramics at the wavelength of 1064 nm was 74.84 %, and the Verdet constant was approximately 275.28 rad·T−1·m−1 at the wavelength of 650 nm.
Magnetic Field Assisted Spark Discharge-Generated Gold Nanostructures: XPS Study of Nitrogen Gas Fate and Chemical Composition of Gold Thin Films
Authors: Ručman Stefan , Thongpan Winai , Sroila Wattikon , Jhuntama Niwat , Singjai Pisith
Published: December 2022

The sparking discharge process utilises high voltage to melt and evaporate tips of electrodes to create particles that can be deposited on substrate. In our research, we examine the influence of a magnetic field and nitrogen flow on gold thin-film formation onto quartz substrate. A positive effect of nitrogen flow and a 0.3 T external magnetic field was observed, in enhancement of surface plasmon band in UV visible and dispersal of nanoparticles without agglomeration. We also detected and described nitrification occurrences of gold measured by XPS at 407 eV and nitridification of quartz substrate on which gold particles are collected. These nitrogen-based chemical reactions occurred during sparking of gold wire inside of ambient air and in the magnetic field, as well during pure nitrogen flow. We measured the valence band electronic structure of gold nanoparticles deposited onto quartz substrate and found that gold thin film prepared in the magnetic field under nitrogen flow has the lowest value of 1.5 eV. Preparation of gold thin films in the magnetic field under nitrogen flow offers a highly dispersed and convenient method for productions of thin films.
Some New Generalizations of Integral Inequalities for Harmonical cr-(h1,h2)-Godunova–Levin Functions and Applications
Authors: Saeed Tareq , Afzal Waqar , Abbas Mujahid , Treanţă Savin , De la Sen Manuel
Published: December 2022

The interval analysis is famous for its ability to deal with uncertain data. This method is useful for addressing models with data that contain inaccuracies. Different concepts are used to handle data uncertainty in an interval analysis, including a pseudo-order relation, inclusion relation, and center–radius (cr)-order relation. This study aims to establish a connection between inequalities and a cr-order relation. In this article, we developed the Hermite–Hadamard (H.H) and Jensen-type inequalities using the notion of harmonical (h1,h2)-Godunova–Levin (GL) functions via a cr-order relation which is very novel in the literature. These new definitions have allowed us to identify many classical and novel special cases that illustrate our main findings. It is possible to unify a large number of well-known convex functions using the principle of this type of convexity. Furthermore, for the sake of checking the validity of our main findings, some nontrivial examples are given.
Explicit Gaussian Variational Approximation for the Poisson Lognormal Mixed Model
Authors: Shi Xiaoping , Wang Xiang-Sheng , Wong Augustine
Published: December 2022

In recent years, the Poisson lognormal mixed model has been frequently used in modeling count data because it can accommodate both the over-dispersion of the data and the existence of within-subject correlation. Since the likelihood function of this model is expressed in terms of an intractable integral, estimating the parameters and obtaining inference for the parameters are challenging problems. Some approximation procedures have been proposed in the literature; however, they are computationally intensive. Moreover, the existing studies of approximate parameter inference using the Gaussian variational approximation method are usually restricted to models with only one predictor. In this paper, we consider the Poisson lognormal mixed model with more than one predictor. By extending the Gaussian variational approximation method, we derive explicit forms for the estimators of the parameters and examine their properties, including the asymptotic distributions of the estimators of the parameters. Accurate inference for the parameters is also obtained. A real-life example demonstrates the applicability of the proposed method, and simulation studies illustrate the accuracy of the proposed method.
Answering Multiple-Choice Questions in Which Examinees Doubt What the True Answer Is among Different Options
Authors: Sánchez Lasheras Fernando , Curbelo José , Baladrón Romero Jaime , García Guerrero Alberto , Peñalver San Cristóbal Carmen , Villacampa Tomás , Jiménez Fonseca Paula
Published: December 2022

This research explores the results that an examinee would obtain if taking a multiple-choice questions test in which they have doubts as to what the true answer is among different options. This problem is analyzed by making use of combinatorics and analytical and sampling methodologies. The Spanish exam through which doctors become medical specialists has been employed as an example. Although it is difficult to imagine that there are candidates who respond randomly to all the questions of such an exam, it is common that they may doubt over what the correct answer is in some questions. The exam consists of a total of 210 multiple-choice questions with 4 answer options. The cut-off mark is calculated as one-third of the average of the 10 best marks in the exam. According to the results obtained, it is possible to affirm that in the case of doubting over two or three of the four possible answers in certain group questions, answering all of them will in most cases lead to obtaining a positive result. Moreover, in the case of doubting between two answer options in all the questions of the MIR test, it would be possible to exceed the cut-off mark.
The Effect of Diameter and Position of Transverse Cylindrical Vortex Generators on Heat Transfer Improvement in a Wavy Channel
Authors: Kotšmíd Stanislav , Brodnianská Zuzana
Published: December 2022

The present study investigates the effect of outer diameter (10 mm and 15 mm) and 5 positions of cylindrical vortex generators (CVGs) installed to the wavy channel in order to improve heat transfer parameters in conjunction with low-pressure drops. The wavy channels with and without CVGs are compared in terms of the local heat transfer coefficient, mean Nusselt number, Colburn factor, friction, and thermal performance for Re in the range of 857 to 8001. Furthermore, the effect of the cooling air flow direction (forward and backward) is assessed. Inserting the CVGs to the channel causes the enhancement of Nusselt numbers and Colburn factors for all CVGs positions and Re in comparison with the channels without CVGs. The maximum thermal performance factor TPFB = 0.8229 was achieved for the channel with CVGs position ‘5’ and 15 mm diameter, backward air flow, and Re = 1677. The backward air flow is more efficient compared with forward air flow since the cooling air gets into the valleys to a greater extent, and thus, better mixing of the fluid occurs. The numerical investigation, conducted with Ansys Fluent software, is compared with the experimental one acquired by holographic interferometry at good agreement of the local heat transfer coefficients. Finally, new correlating equations for the mean Nusselt number were created.
Effects of Heat Treatment on Microstructure and Mechanical Properties of a Transformation-Induced Plasticity-Aided Economical Duplex Stainless Steel
Authors: Jia Yandong , Yin Xingyu , Xu Yulai , Wang Gang
Published: December 2022

In order to obtain steel with high tensile strength and elongation and good pitting resistance, the economical duplex stainless steel with and without the addition of tungsten (W) was prepared in this paper. The comparison and distribution of the two phases were controlled by optimizing the heat treatment process. The highest product of tensile strength and elongation of Cr19 series duplex stainless steel (DSS) DSS were obtained after solution treatment at 1050 °C for 5 min, up to 58692 Mpa%(876 Mpa * 67%), when the area f.raction of α was about 50.7%. The addition of tungsten reduces tensile strength due to the increased area fraction of α at 1050–1150 °C. Finer grain size leads to higher tensile strength after solution treatment at 1050 °C. The microstructure is characterized by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The steels exhibit an excellent transformation-induced plasticity (TRIP) effect after the solution treated is at 1050 °C, which may primarily be due to the existence of a more unstable austenite phase. The TRIP effect acts through the phase transformation of γ to α′-M during high deformation, and the orientation relationship of {111}γ || {110}α′-M & <110>γ || <001>α′-M belongs to the standard variants of Nishiyama–Wassermann relationship.
Experimental Investigation of the Isothermal Section in the Al–Si–Y System at 773 K
Authors: Yang Lu , Qin Haiqing , Yang Qingkai , Huang Kailin , Lu Zhao , Yao Qingrong , Deng Jianqiu , Cheng Lichun , Huang Caimin , Long Qianxin , Wang Jiang , Zhou Huaiying
Published: December 2022

The phase equilibrium and phase transformation of the Al–Si–Y ternary system were investigated in 80 annealed alloys using an electron probe microanalysis (EPMA), X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The phase equilibrium at 773 K was determined, and the phase distribution and solid solubility of the Al–Si–Y isothermal section at 773 K were obtained. A total of 23 three-phase zones and 4 two-phase zones were obtained, and 2 new ternary compounds, AlSi4Y5 and Al2Si3Y5, were identified from the non-aluminum-rich corner. Additionally, the phase transition temperatures of representative alloys were determined by the DSC method, and then the phase transition temperatures were processed to obtain the experimental points of vertical sections. In the Al–Si–Y alloy system, the phase diagrams of the vertical sections with X(Al) = 90 at.%, 80 at.%, 70 at.% and 60 at.% at the aluminum-rich corner were calculated, and then the experimental points were inserted into the vertical section phase diagrams. The results of the vertical sectional experiments obtained from the validation experiments are in good agreement with the vertical sectional data obtained from the calculations, indicating that the validated thermodynamic description is useful for the microstructure design of the aluminum-rich corner of the Al–Si–Y ternary alloy.
Copper-Decorated Ti3C2Tx MXene Electrocatalyst for Hydrogen Evolution Reaction
Authors: Wang Buxiang , Shu Qing , Chen Haodong , Xing Xuyao , Wu Qiong , Zhang Li
Published: December 2022

It remains a formidable challenge to prepare an economical and stable electrocatalyst for hydrogen evolution reaction using non-precious metals. In this study, MXene (Ti3C2Tx) nanosheets were prepared by high-energy ultrasound treatment, and Cu nanoparticles were prepared by NaBH4 as a reducing agent. Then, the electrocatalyst Cu/Ti3C2Tx, suitable for hydrogen evolution reaction (HER), was prepared by supporting Cu with Ti3C2Tx. The structure, morphology, crystal phase and valence state of the obtained catalyst were determined by a variety of characterization analysis methods, and the influence of these properties on the catalytic performance is discussed here. The results of Brunner–Emmet–Teller (BET) showed that Ti3C2Tx can effectively inhibit Cu agglomeration. Results of Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) showed that Cu has metallic and oxidized states. X-ray Photoelectron Spectroscopy (XPS) further revealed the existence of multivalent states in Cu, which would contribute to the formation of electron transfer channels and the enhancement of electrocatalytic activity. In addition, the Cu/Ti3C2Tx catalyst has strong hydrophilicity, as measured by contact angle, which is conducive to HER. Ti3C2Tx has acceptable electrocatalytic hydrogen evolution performance: under alkaline conditions, when the current density is 10 mA cm−2, HER overpotential is as low as 128 mV and the Tafel slope is as low as 126 mV dec−1. Meanwhile, Ti3C2Tx showed adequate stability for HER (94.0% of the initial mass activity after 1000 CV cycles). This work offers insights into the development of high-performance non-precious metal-based catalysts to achieve the high performance of HER in alkaline electrolytes.
Flow Stress Optimization of Inconel 718 Based on a Coupled Simulation of Material-Forming Analysis and Joule Heating Analysis
Authors: Park Jong-Soo , Kim Seung-Woo , Lim Hyung-Cheol , Kang Jong-Hun
Published: December 2022

Inconel 718 is a well-known nickel-based superalloy used for high-temperature applications. The aim of the present study was to formulate a constitutive equation (CE) that can be used to account for the deformation behavior of Inconel 718. Compression tests were performed using Gleeble 3800, a thermomechanical simulator, at temperatures ranging from 900 to 1200 °C, at strain rates varying from 0.1 to 10/s. Before compression tests, each specimen was rapidly heated to the desired test temperature while the initial contact pressure was kept relatively low. Thus, compression was performed while the temperature of the entire system, including the specimen and the die, was not uniform. Before conducting an upsetting finite element analysis to determine CE parameters, the heating conditions applied in the Gleeble tests were first subjected to a Joule heating analysis, to simulate the temperature distribution in each specimen prior to the compression process. The spatial temperature distribution of the specimen and the die were determined using a Joule heating analysis, and these results were used as input data for the subsequent finite element analysis of the compression process. From this, the parameters in the obtained Hansel–Spittel equation were estimated for each temperature condition, by employing the regression optimization method, which was used to minimize the deviation between experimental and simulated load values. To validate this optimization process, the experimentally measured flow stresses with respect to the strain rate for each temperature condition were compared with the forming load, determined by the finite element analysis of the compression process using the optimized CE obtained in the present study. It was confirmed that when the optimization process was applied, there was a decrease in the root mean square error. The major findings confirmed the validity of the CE optimization method combined with Joule heating analysis for determining the CE’s parameters for high-temperature applications.
Studies on Parameters Affecting Temperature of Liquid Steel and Prediction Using Modified AdaBoost.RT Algorithm Ensemble Extreme Learning Machine
Authors: Wang Senhui , Li Haifeng , Zhang Yongjie , Wang Cheng , He Xiang , Chen Denghong , Yang Ke
Published: December 2022

The present work aimed to develop a predictive model for the end temperature of liquid steel in advance to support the smooth functioning of a vacuum tank degasser (VTD). An ensemble model that combines extreme learning machine (ELM) with a self-adaptive AdaBoost.RT algorithm was established for the regression problem. Based on analyzing the energy equilibrium of the VTD system, the factors were determined for predicting the end temperature of liquid steel. To establish a hybrid ensemble prediction model, an ELM algorithm was selected as the ensemble predictor due to its strong performance and robustness, and a modification of the AdaBoost.RT algorithm is proposed to overcome the drawback of the original AdaBoost.RT by embedding statistical theory to dynamically self-adjust the threshold value. For efficient VTD operations, an ensemble model that combines ELM with the self-adaptive AdaBoost.RT algorithm was established to model the end temperature of liquid steel. The proposed approach was analyzed and validated on actual production data derived from a steelmaking workshop in Baosteel. The experimental results reveal that the proposed model can improve the generalization performance, and the accuracy of the model is feasible for the secondary steel refining process. In addition, a polynomial equation is obtained from the ensemble predictive model for calculating the value of the end temperature. The predicted results are in good agreement with the actual data with <1.7% error.
Atomistic Simulation of Ultrasonic Welding of Copper
Authors: Nazarov Ayrat , Bachurin Dmitry , Ni Zenglei
Published: December 2022

Molecular dynamics simulations of ultrasonic welding of two blocks of fcc copper containing asperities under the conditions of a constant clamping pressure and sinusoidal shear displacements were performed. Two different atomistic models of blocks were simulated: Model I with no misorientation between the lattices, and Model II with a special misorientation of 78.46°. Alternating shearing results in a plastic deformation of the interface layers and is accompanied by the emission of partial dislocations. Misorientation between the joined blocks contributes significantly to an interface sliding, interface migration, and pores healing during ultrasonic processing. A significantly larger increase in temperature occurs during shearing in Model II than in Model I. The applied pressure has almost no effect on the interface temperature in both studied models. The temperature increases almost up to maximum values after the first shear cycle, and then practically does not undergo changes in the next four cycles. The temperature at the interface in Model II is significantly higher than that in Model I. The change in the porosity of the interface and its structure are analyzed. The results obtained in the present work contribute to a deeper understanding of the processes occurring at the atomic level during ultrasonic welding of metals.
Microstructure and Mechanical Properties of ZL205A Aluminum Alloy Produced by Squeeze Casting after Heat Treatment
Authors: Jiang Hong , Zhang Linfan , Zhao Biwei , Sun Ming , He Meifeng
Published: December 2022

In this paper, ZL205A (AlCu5Mn alloy) castings were prepared by squeeze casting. The effects of solution and ageing treatment on the microstructure and mechanical properties of ZL205A castings were studied by metallography, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and mechanical properties tests. The results showed that most of the θ(Al2Cu) and T(Al12CuMn2) phases in squeeze-cast ZL205A dissolved into the α(Al) matrix after solution treatment for 15 h. The fine precipitates gradually increased with the ageing time. The ultimate tensile strength of the specimen aged for 6 h was the highest of 467 MPa and the elongation was up to 15.1%, showing good comprehensive mechanical properties.
Microstructure and Mechanical Properties of Selective Laser Melted Reduced Activation Ferritic/Martensitic Steel
Authors: Yuan Zihao , Xiao Chenyu , Liu Hao , Sun Xuejing , Zhao Guangyi , Liao Hongbin , Qian Wei , Yuan Jingkun , Lao Changshi , Wang Huajie
Published: December 2022

Cube and tensile samples of reduced activation ferritic/martensitic steel were formed at different laser powers and scanning velocities using a selective laser melting process; the microstructural characteristics and tensile properties of the cube and tensile samples were investigated in this study. The experimental results showed that the SLMed CLF-1 samples that formed with selected laser melting were near-fully dense, and the relative density of the SLMed CLF-1 samples exceeded 99%. Meanwhile, there were numerous nano-sized spherical and needle-like precipitate dispersions distributed in the grains and boundary of the grains, and the precipitates were mainly composed of M23C6 carbide and MX carbide. The microstructure was composed of columnar grains and equiaxed grains arranged in a sequence, and the smallest average size of the grains was 15 ± 2.1 µm when measured at 320 W of power and 800 mm/s scanning velocity. In addition, the sample at 320 W of power and 800 mm/s scanning velocity exhibited higher yield strength (875 ± 6.0 MPa) and higher elongation (25.6 ± 0.8%) than that of the sample at 200 W of power, 800 mm/s scanning velocity, yield strength of 715 ± 1.5 MPa, and elongation of 22.6 ± 1.2%.
Soliton Microcomb on Chip Integrated Si3N4 Microresonators with Power Amplification in Erbium-Doped Optical Mono-Core Fiber
Authors: Chen Xinpeng , Sun Suwan , Ji Weizhu , Ding Xingxing , Gao You , Liu Tuo , Wen Jianxiang , Guo Hairun , Wang Tingyun
Published: December 2022

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated Si3N4 microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications.
Comparison between Symptomatic and Asymptomatic Mice after Clostridioides difficile Infection Reveals Novel Inflammatory Pathways and Contributing Microbiota
Authors: AbdelKhalek Ahmed , Narayanan Sanjeev K.
Published: December 2022

Clostridioides difficile causes the highest number of nosocomial infections. Currently, treatment options for C. difficile infection (CDI) are very limited, resulting in poor treatment outcomes and high recurrence rates. Although the disease caused by CDI is inflammatory in nature, the role of inflammation in the development of CDI symptoms is contradictory and not completely understood. Hence, the use of anti-inflammatory medication is debatable in CDI. In the current study, we evaluated the genetic and microbiome profiles of mice after infection with C. difficile. These mice were categorized based on the severity of CDI and the results were viewed accordingly. Our results indicate that certain genes are upregulated in severe CDI more than in the moderate case. These include oncostatin-M (OSM), matrix metalloprotease 8 (MMP8), triggering receptor expressed on myeloid cells 1 (Trem-1), and dual oxidase 2 (Duox2). We also investigated the microbiome composition of CDI mice before and after infecting with C. difficile. The results show that C. difficile abundance is not indicative of diseases severity. Certain bacterial species (e.g., Citrobacter) were enriched while others (e.g., Turicibacter) were absent in severe CDI. This study identifies novel inflammatory pathways and bacterial species with a potential role in determining the severity of CDI.
Maximizing Laboratory Production of Aflatoxins and Fumonisins for Use in Experimental Animal Feeds
Authors: Ochieng Phillis E. , Kemboi David C. , Scippo Marie-Louise , Gathumbi James K. , Kangethe Erastus , Doupovec Barbara , Croubels Siska , Lindahl Johanna F. , Antonissen Gunther , Okoth Sheila
Published: December 2022

Warm and humid climatic conditions coupled with poor agricultural practices in sub-Saharan Africa favor the contamination of food and feed by Aspergillus flavus and Fusarium verticillioides fungi, which subsequently may produce aflatoxins (AFs) and fumonisins (FBs), respectively. The growth of fungi and the production of mycotoxins are influenced by physical (temperature, pH, water activity, light and aeration), nutritional, and biological factors. This study aimed at optimizing the conditions for the laboratory production of large quantities of AFs and FBs for use in the animal experiments. A. flavus and F. verticillioides strains, previously isolated from maize in Kenya, were used. Levels of AFB1 and total FBs (FB1, FB2, and FB3) in different growth substrates were screened using ELISA methods. Maize kernels inoculated with three different strains of A. flavus simultaneously and incubated at 29 °C for 21 days had the highest AFB1 level of 12,550 ± 3397 μg/kg of substrate. The highest level of total FBs (386,533 ± 153,302 μg/kg of substrate) was detected in cracked maize inoculated with three different strains of F. verticillioides and incubated for 21 days at temperatures of 22–25 °C in a growth chamber fitted with yellow light. These two methods are recommended for the mass production of AFB1 and FBs for animal feeding trials.
Geology, Pyrite Geochemistry and Metallogenic Mechanism of the Wulong Gold Deposit in Liaodong Peninsula, North China Craton
Authors: Zhang Zhichao , Wang Yuwang , He Jiyu , Li Dedong , Qiu Haicheng , Liu Fuxing , Lai Chunkit
Published: December 2022

The Wulong deposit is a large gold deposit in the Liaodong peninsula (North China Craton). Silicic and pyrite alterations are well-developed in the deposit and closely related to mineralization. The least altered and silicified microdiorite samples were selected for major and trace element analyses to reveal the elemental migration/enrichment. Pyrites of stage 1 (Py1) were selected for backscattered electron (BSE) imaging and LA-ICP-MS trace element analyses to reveal their possible metallogenic link. Mass balance calculation showed that Al2O3, CaO, Fe2O3, K2O, SiO2, Ag, As, Cu, and Pb were brought in, whereas MgO, Na2O, FeO, Cr, Zn, and Ni were leached out during silicification. LA-ICP-MS trace element analyses show that Py1 has higher Au and Zn contents than Py2 and Py3, Py2 has higher Au and Cu contents than Py1 and Py3, and Py3 has higher Pb, Cu, and As contents than Py1 and Py2. During the process of silicification and pyritization, the depleted H+ concentration and HS− concentration in the ore-forming fluids led to instability of the Au(HS)2− complexes and led to gold precipitation. The depleted sulfur and the reduced temperature during the precipitated of bismuthinite also led to instability of the Au(HS)2− complexes and gold precipitation.
Audio Magnetotellurics Study of the Geoelectric Structure across the Zhugongtang Giant Lead–Zinc Deposit, NW Guizhou Province, China
Authors: Pitiya Regean , Lu Mao , Chen Rujun , Nong Guanhai , Chen Siwen , Yao Hongchun , Shen Ruijie , Jiang Enhua
Published: December 2022

Non-invasive geophysical exploration methods a play key role in the exploration of ore deposits. In the present study, the audio-frequency magnetotelluric (AMT) method was applied to metallic mineral exploration. The metallic mineral deposit targeted was the recently discovered super large lead–zinc deposit of the Zhugongtang mining area of Hezhang County in the northwestern Guizhou province in China. The main objectives of this study were to estimate the geoelectric strike and generate geoelectric models that estimate both the depth and distribution of resistivity structures across the deposit. To achieve the objectives, we deployed sixty-one (61) AMT survey sites with an interstation separation of 20 m on a 1280 m survey track perpendicular to the geological strike across the Zhugongtang deposit. We operated in fifty-three (53) frequencies in the range 1–10,400 Hz to record the resistivity distribution of subsurface to a depth of more than 1200 m. The results from the AMT data computations estimated the geoelectric strike that varies between NE285° and NE315°. This range of strikes suggested that structures across the deposit are oriented in the NW–SE direction. Obtained two-dimensional (2D) models elucidated a remarkably low resistivity body (<15 Ωm) at an elevation of less than 1600 m above sea level (>0.50 km depth), thus extending to great depth and were interpreted as lead–zinc mineralization. Furthermore, low resistivity (<63 Ωm) features were imaged both in superficial and deeper depths and interpreted as shale, sandstone, claystone, and silty mudstone units. Dolomite and limestone lithologies were found widely distributed with high resistivity (>1000 Ωm). Bioclastic limestone and dolomite limestone were inferred and characterized by moderate-high resistivity (>250 Ωm) and were not widely distributed. A unit of basalts was found with moderate resistivity (>63 Ωm). In addition, it was also found that regions with high number of faults tend to have low resistivity values compared to regions with a low fault number. In summary, this case study presents the results of applying an AMT approach to explore the conductivity characteristics of structures across the Zhugongtang deposit. The findings may contribute to the literature about this deposit.
The Multiple Sclerosis Modulatory Potential of Natural Multi-Targeting Antioxidants
Authors: Theodosis-Nobelos Panagiotis , Rekka Eleni A.
Published: December 2022

Multiple sclerosis (MS) is a complex neurodegenerative disease. Although its pathogenesis is rather vague in some aspects, it is well known to be an inflammatory process characterized by inflammatory cytokine release and oxidative burden, resulting in demyelination and reduced remyelination and axonal survival together with microglial activation. Antioxidant compounds are gaining interest towards the manipulation of MS, since they offer, in most of the cases, many benefits, due to their pleiotropical activity, that mainly derives from the oxidative stress decrease. This review analyzes research articles, of the last decade, which describe biological in vitro, in vivo and clinical evaluation of various categories of the most therapeutically applied natural antioxidant compounds, and some of their derivatives, with anti-MS activity. It also summarizes some of the main characteristics of MS and the role the reactive oxygen and nitrogen species may have in its progression, as well as their relation with the other mechanistic aspects of the disease, in order for the multi-targeting potential of those antioxidants to be defined and the source of origination of such activity explained. Antioxidant compounds with specific characteristics are expected to affect positively some aspects of the disease, and their potential may render them as effective candidates for neurological impairment reduction in combination with the MS treatment regimen. However, more studies are needed in order such antioxidants to be established as recommended treatment to MS patients.
Vanadium Hexacyanoferrate as a High-Capacity and High-Voltage Cathode for Aqueous Rechargeable Zinc Ion Batteries
Authors: Zhang Shijing , Pang Qiang , Ai Yuqing , He Wei , Fu Yao , Xing Mingming , Tian Ying , Luo Xixian
Published: December 2022

Prussian blue analogs (PBAs) are widely used as electrode materials for secondary batteries because of their cheapness, ease of synthesis, and unique structural properties. Nevertheless, the unsatisfactory capacity and cyclic stability of PBAs are seriously preventing their practical applications. Here, vanadium hexacyanoferrate (VHCF) is successfully prepared and used as a cathode for aqueous zinc-ion batteries (AZIBs). When using 3 M Zn(CF3SO3)2 as the electrolyte, a high capacity of ~230 mA h g−1 and a high voltage of ~1.2 V can be achieved. The XRD result and XPS analysis indicate that the outstanding Zn2+ storage capability is due to the presence of dual electrochemical redox centers in VHCF (Fe2+ ⇋ Fe3+ and V5+ ⇋ V4+ ⇋ V3+). However, the battery shows a short cycle life (7.1% remaining capacity after 1000 cycles) due to the dissolution of VHCF. To elongate the cycle life of the battery, a high-concentration hybrid electrolyte is used to reduce the activity of water molecules. The improved battery exhibits an impressive capacity of 235.8 mA h g−1 and good capacity retention (92.9%) after 1000 cycles.
A Comparative Study of the Band-Edge Exciton Fine Structure in Zinc Blende and Wurtzite CdSe Nanocrystals
Authors: Golovatenko Aleksandr A. , Kalitukha Ina V. , Dimitriev Grigorii S. , Sapega Victor F. , Rakhlin Maxim V. , Galimov Aidar I. , Shubina Tatiana V. , Shornikova Elena V. , Qiang Gang , Yakovlev Dmitri R. , Bayer Manfred , Biermann Amelie , Hoffmann Axel , Aubert Tangi , Hens Zeger , Rodina Anna V.
Published: December 2022

In this paper, we studied the role of the crystal structure in spheroidal CdSe nanocrystals on the band-edge exciton fine structure. Ensembles of zinc blende and wurtzite CdSe nanocrystals are investigated experimentally by two optical techniques: fluorescence line narrowing (FLN) and time-resolved photoluminescence. We argue that the zero-phonon line evaluated by the FLN technique gives the ensemble-averaged energy splitting between the lowest bright and dark exciton states, while the activation energy from the temperature-dependent photoluminescence decay is smaller and corresponds to the energy of an acoustic phonon. The energy splittings between the bright and dark exciton states determined using the FLN technique are found to be the same for zinc blende and wurtzite CdSe nanocrystals. Within the effective mass approximation, we develop a theoretical model considering the following factors: (i) influence of the nanocrystal shape on the bright–dark exciton splitting and the oscillator strength of the bright exciton, and (ii) shape dispersion in the ensemble of the nanocrystals. We show that these two factors result in similar calculated zero-phonon lines in zinc blende and wurtzite CdSe nanocrystals. The account of the nanocrystals shape dispersion allows us to evaluate the linewidth of the zero-phonon line.
Analysis of Electrochemical Performance with Dispersion Degree of CNTs in Electrode According to Ultrasonication Process and Slurry Viscosity for Lithium-Ion Battery
Authors: Choi Jaehong , Lee Chaewon , Park Sungwoo , Embleton Tom James , Ko Kyungmok , Jo Mina , Saleem Saqib Kashif , Yun Jeongsik , Jo Minki , Son Yoonkook , Oh Pilgun
Published: December 2022

Lithium-ion batteries (LIBs) continue to dominate the battery market with their efficient energy storage abilities and their ongoing development. However, at high charge/discharge C-rates their electrochemical performance decreases significantly. To improve the power density properties of LIBs, it is important to form a uniform electron transfer network in the cathode electrode via the addition of conductive additives. Carbon nanotubes (CNTs) with high crystallinity, high electrical conductivity, and high aspect ratio properties have gathered significant interest as cathode electrode conductive additives. However, due to the high aggregational properties of CNTs, it is difficult to form a uniform network for electron transfer within the electrode. In this study, to help fabricate electrodes with well-dispersed CNTs, various electrodes were prepared by controlling (i) the mixing order of the conductive material, binder, and active material, and (ii) the sonication process of the CNTs/NMP solution before the electrode slurry preparation. When the binder was mixed with a well sonicated CNTs/NMP solution, the CNTs uniformly adsorbed to the then added cathode material of LiNi0.6Co0.2Mn0.2O2 and were well-dispersed to form a flowing uniform network. This electrode fabrication process achieved > 98.74% capacity retention after 50 cycles at 5C via suppressed polarization at high current densities and a more reversible H1-M phase transition of the active material. Our study presents a novel design benchmark for the fabricating of electrodes applying well-dispersed CNTs, which can facilitate the application of LIBs in high current density applications.
Identification of Zirconia Particle Uptake in Human Osteoblasts by ToF-SIMS Analysis and Particle-Size Effects on Cell Metabolism
Authors: Welle Alexander , Rabel Kerstin , Schwotzer Matthias , Kohal Ralf Joachim , Steinberg Thorsten , Altmann Brigitte
Published: December 2022

As the use of zirconia-based nano-ceramics is rising in dentistry, the examination of possible biological effects caused by released nanoparticles on oral target tissues, such as bone, is gaining importance. The aim of this investigation was to identify a possible internalization of differently sized zirconia nanoparticles (ZrNP) into human osteoblasts applying Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), and to examine whether ZrNP exposure affected the metabolic activity of the cells. Since ToF-SIMS has a low probing depth (about 5 nm), visualizing the ZrNP required the controlled erosion of the sample by oxygen bombardment. This procedure removed organic matter, uncovering the internalized ZrNP and leaving the hard particles practically unaffected. It was demonstrated that osteoblasts internalized ZrNP within 24 h in a size-dependent manner. Regarding the cellular metabolic activity, metabolization of alamarBlue by osteoblasts revealed a size- and time-dependent unfavorable effect of ZrNP, with the smallest ZrNP exerting the most pronounced effect. These findings point to different uptake efficiencies of the differently sized ZrNP by human osteoblasts. Furthermore, it was proven that ToF-SIMS is a powerful technique for the detection of zirconia-based nano/microparticles that can be applied for the cell-based validation of clinically relevant materials at the nano/micro scale.
Strengthening and Toughening CNTs/Mg Composites by OpTimizing the Grinding Time of Magnesium Powder
Authors: Ding Yunpeng , Zhang Yizhuang , Li Zhiyuan , Liu Changhong , Wang Hanying , Zhao Xin , Zhang Xinfang , Xu Jilei , Guo Xiaoqin
Published: December 2022

In this paper, CNT/Mg composites with high compressive properties were prepared by using Ni-plated CNT and pure magnesium powder as raw materials through the grinding of magnesium powder, ball-milling mixing and hot-pressing sintering. The effect of grinding time for finer magnesium powder on the microstructure and properties of the final composites was studied mainly by SEM, XRD, HRTEM and compression tests. The results show that with the prolongation of milling time, the magnesium particle size decreases gradually and the CNT dispersion becomes more uniform. Moreover, the nickel layer on the surface of CNT reacts with highly active broken magnesium powder in the sintering process to generate MgNi2 intermediate alloy, which significantly improves interface bonding. The strength and fracture strain of composites are significantly increased by the combined action of the uniform distribution of CNTs and strong interface bonding from the MgNi2 phase. The compressive strength, yield strength and fracture strain of the composites, prepared with a 60 h grinding of magnesium powder, reached 268%, 272% and 279% of those in composites without the grinding of magnesium powder.