bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperatures and Moisture Content on the Fracture Properties of Engineered Cementitious Composites (ECC)
Authors: Gao Shuling , Xie Puxu
Published: April 2022

This research will help to improve our understanding of the fracture properties of ECC at low temperatures (long-term low temperatures, freeze–thaw) and evaluate the safety properties of ECC under low-temperature conditions. Three levels of saturation (saturated, semi-saturated, and dry), four target temperatures (20, 0, −20, and −60 °C), and the effect of the coupled of the two on the mode I fracture properties of ECC were investigated. Then, we compared and analyzed the fracture properties of ECC loaded at 20 and −20 °C, after different freeze–thaw cycles (25, 50, 100 cycles), which were compared with saturated specimens without freeze–thaw at the four target temperatures to analyze the differences in low-temperature and freeze–thaw failure mechanisms. Temperatures and saturation have a significant effect on the fracture properties. Low temperatures and freeze–thaw treatments both decreased the nominal fracture energy of ECC. Distinct differences in matrix and fiber-matrix interface damage mechanisms have been discovered. Low temperatures treatment transforms ECC from a ductile to a brittle fracture mode. However, even after 100 freeze–thaw cycles, it remains ductile fractured. This study complements the deficiencies of ECC in low-temperature theoretical and experimental applications, and it sets the stage for a broad range of ECC applications.
Wire + Arc Additive Manufacturing and Heat Treatment of Super Martensitic Stainless Steel with a Refined Microstructure and Excellent Mechanical Properties
Authors: Zou Xiaodong , Niu Ben , Pan Linlin , Yi Jianglong
Published: April 2022

Due to the advantages of relatively low cost, increased energy efficiency, increased deposition rate, and the capacity to create medium to large scale components, wire + arc additive manufacturing (WAAM) has gained growing interest. Super martensitic stainless steel (SMSS) combines outstanding strength, ductility, and corrosion resistance, making it a great option for WAAM. In the present work, an SMSS component was successfully produced by WAAM. Additionally, the influence of post-manufactured heat treatment on the microstructural characteristics and mechanical properties of SMSS components was systematically examined. A microstructural analysis of the as-printed and heat-treated samples revealed the formation of typical martensite and a small amount of retained austenite. However, the sample heat-treated by solutionizing at 1050 °C for 1 h followed by aging at 400 °C for 2 h exhibited a finer martensitic structure with an effective grain size of 5.6 μm compared to as-printed sample, leading to an increase in ultimate tensile strength from 1054 ± 6 MPa to 1141 ± 3 MPa with a concomitant increase in elongation from 7.8 ± 0.4% to 12.6 ± 0.2%. Additionally, the fracture morphology of the solution + aging sample demonstrated a more uniform distribution and greater mean size of dimples, indicating better ductility.
Manufacturing of Pure Iron by Cold Rolling and Investigation for Application in Magnetic Flux Shielding
Authors: Satpute Nitin , Dhoka Prakash , Iwaniec Marek , Jabade Siddharth , Karande Pankaj
Published: April 2022

The presented work investigates a novel method to manufacture 98.8% pure iron strips having high permeability and better saturation flux density for application in magnetic flux shielding. The proposed method uses electro-deposition and cold rolling along with intermediate annealing in a controlled environment to manufacture 0.05–0.5 mm thick pure iron strips. The presented approach is inexpensive, has better control over scaling/oxidation and requires low energy than that of the conventional methods of pure iron manufacturing by pyrometallurgical methods. Important magnetic and mechanical properties of the pure iron are investigated in the context of the application of the material in magnetic shielding. Magnetic properties of the material are investigated by following IEC60404-4 standard and toroidal coil test to determine hysteresis curve, magnetic permeability and core losses. The microstructure is investigated with an optical microscope and scanning electron microscopy to study grain size and defects after cold rolling and annealing. The properties derived from the experimental methods are used in finite element analysis to study the application of the material for static, low-frequency and high-frequency magnetic shielding. Theoretical simulation results for magnetic shielding around a current-carrying conductor and micro-electromechanical inductive sensor system are discussed. Further shielding performance of the material is compared with that of the other candidate materials, including that of Mu-metal and electrical steel. It is demonstrated that the pure iron strips manufactured in the present study can be used for magnetic shielding in the case of low-frequency applications. In the case of high-frequency applications, a conducting layer can be combined to ensure the required shielding effectiveness in the case of Class 2 applications.
Three-Dimensional Nanoscale Morphological Surface Analysis of Polymeric Particles Containing Allium sativum Essential Oil
Authors: de Oliveira Larissa Medeiros , Matos Robert Saraiva , Ţălu Ştefan , Rocha Ana Luisa Farias , de Aguiar Nunes Ronald Zico , Bezerra Jaqueline de Araújo , Campelo Felix Pedro Henrique , Inada Natália Mayumi , Sanches Edgar Aparecido , da Fonseca Filho Henrique Duarte
Published: April 2022

Biodegradable particles were developed using poly-ε-caprolactone and gelatin carriers containing different concentrations of Allium sativum essential oil (EO) (360 µg/mL, 420 µg/mL, and 460 µg/mL). Atomic force microscopy was useful to evaluate the particles’ surface based on morphological parameters. The particles’ size varied from 150 nm to 300 nm. The diameter was related to the increase of the particles’ height as a function of the EO concentration, influencing the roughness of the surface core values (from 20 to 30 nm) and surface irregularity. The spatial parameters Str (texture aspect ratio) and Std (texture direction) revealed low spatial frequency components. The hybrid parameters Sdq (root mean square gradient) and Sdr (interfacial area ratio) also increased as a function of the EO concentration, revealing fewer flat particles. On the other hand, the functional parameters (inverse areal material ratio and peak extreme height) suggested differences in surface irregularities. Higher concentrations of EO resulted in greater microtexture asperity on the particles’ surface, as well as sharper peaks. The nanoscale morphological surface analysis allowed the determination of the most appropriate concentration of encapsulated EO, influencing statistical surface parameters.
Thermodynamic Relationships for Perfectly Elastic Solids Undergoing Steady-State Heat Flow
Authors: Hofmeister Anne M. , Criss Everett M. , Criss Robert E.
Published: April 2022

Available data on insulating, semiconducting, and metallic solids verify our new model that incorporates steady-state heat flow into a macroscopic, thermodynamic description of solids, with agreement being best for isotropic examples. Our model is based on: (1) mass and energy conservation; (2) Fourier’s law; (3) Stefan–Boltzmann’s law; and (4) rigidity, which is a large, yet heretofore neglected, energy reservoir with no counterpart in gases. To account for rigidity while neglecting dissipation, we consider the ideal, limiting case of a perfectly frictionless elastic solid (PFES) which does not generate heat from stress. Its equation-of-state is independent of the energetics, as in the historic model. We show that pressure-volume work (PdV) in a PFES arises from internal interatomic forces, which are linked to Young’s modulus (Ξ) and a constant (n) accounting for cation coordination. Steady-state conditions are adiabatic since heat content (Q) is constant. Because average temperature is also constant and the thermal gradient is fixed in space, conditions are simultaneously isothermal: Under these dual restrictions, thermal transport properties do not enter into our analysis. We find that adiabatic and isothermal bulk moduli (B) are equal. Moreover, Q/V depends on temperature only. Distinguishing deformation from volume changes elucidates how solids thermally expand. These findings lead to simple descriptions of the two specific heats in solids: ∂ln(cP)/∂P = −1/B; cP = nΞ times thermal expansivity divided by density; cP = cVnΞ/B. Implications of our validated formulae are briefly covered.
Numerical Investigation of Effect of Drum Barrel on Coal-Loading Performance of Thin-Coal-Seam Shearer Machines
Authors: Zhang Xiaodi , Gao Kuidong , Zeng Qingliang , Lin Lisong , Wu Tianjiao , Sun Liqing
Published: April 2022

Thin-coal-seam shearer mining efficiency is seriously restricted by the poor loading performance of the drum. The loading of the drum to the cracked coal lumps is based on a screw-conveying mechanism, and its loading performance is influenced by many structural parameters, including drum width, helical angle, axial tilt angle, number of blades and form and diameter of the barrel. The barrel diameter directly influences the drum envelope zone’s capacity, and its influence on loading performance is not yet clear. Therefore, this work first compared the drum-loading results between experiments and numerical modeling, and the results proved that the application of the discrete element method (DEM) to the modeling drum loading process is feasible and the results are reliable. Secondly, the influence of barrel diameter on particles’ axial velocity, loading rate and web depth was studied using the ejection and pushing modes. The results showed that the particles’ axial velocity has a noticeable impact on loading rate under ejection loading conditions, and the loading rate first increases and then decreases with the increase in barrel diameter. When the diameter is less than 700 mm in drum-pushing modes, the particles’ axial velocity plays an important role on drum loading; the filling level has an obvious impact on loading performance when the barrel diameter is larger than 700 mm. The drum loading ejection rate is 25% higher than that of pushing mode, which is due to the loading rate of particles located in a web depth from 300 to 600 mm. The influence of barrel diameter on loading performance using drum ejection is more obvious than that in pushing mode. The results provide a reference for drum structural design to some extent.
Robot-Based Automation for Upper and Sole Manufacturing in Shoe Production
Authors: Kim Min-Gyu , Kim Juhyun , Chung Seong Youb , Jin Maolin , Hwang Myun Joong
Published: April 2022

(1) Background: Conventional shoe manufacturing involves many processes that most workers avoid because of loud noises and harmful environments. Therefore, a robot-based shoe manufacturing system is needed to implement an automated process. (2) Aim: We propose a new robot-based shoe manufacturing automation system that includes an automatic robotic solution for replacing the manual manufacturing processes of the upper and sole. (3) Methods: For the upper manufacturing process, a new trajectory acquisition system with a digitizer and a shoe last turning device is proposed. A method to plan the robot’s tool path for roughing and cementing by industrial robot manipulators is also presented. For the sole manufacturing process, we adopted an industrial robot manipulator with a 3-D scanning system and a cementing tool. A trajectory generation algorithm for cementing the outer and inner sides of the sole by transforming 3-D information of the sole into a 6-D posture for the robot is proposed. (4) Results: All developed systems and proposed algorithms are applied to an automated production testbed, and their performances are experimentally verified. (5) Conclusions: The proposed system and methods can be applied for upper and sole manufacturing processes according to evaluation experiments in a demonstrative production line.
Temperature Dynamic Characteristics Analysis and Thermal Load Dissipation Assessment for Airliner Hydraulic System in a Full Flight Mission Profile
Authors: Li Dong , Dong Sujun , Wang Jun , Li Yunhua
Published: April 2022

This paper deals with the modeling of the thermal load and the simulation of thermal dynamic characteristics for the hydraulic system of a large airliner in a full mission profile. Firstly, the formation mechanism of the thermal load in the hydraulic system is analyzed, and thermal dynamic modeling is conducted of the hydraulic components of an hydraulic system with an immersed heat exchanger employing the lumped parameter thermal node method and oil temperature and power loss of each key node within the hydraulic system within a full mission profile. Then, a thermal dynamic simulation model based on MATLAB/Simulink is established, and the temperatures at the nodes of different components and the absorptive capacity of the fuel heat sink in the thermal management module are calculated. The simulation results show that the thermal management scheme of the heat exchanger, located in the return oil pipeline of the hydraulic piston pump housing and immersed in the central fuel tank, can dissipate the thermal load of the system. This work is of important significance for temperature analysis and thermal load dissipation of the airliner hydraulic system.
Static and Dynamic Magneto-Elastic Sensing Properties of Fe-Al Alloy Powder-Epoxy Composite Patches
Authors: Na Suok-Min , Yoo Byungseok , Pines Darryll J. , Yoo Jin-Hyeong , Jones Nicholas J.
Published: April 2022

By combining the two types of magnetoelastic and magnetochromatic materials in an epoxy, we can make a hybrid system that exhibits an optical response due to an elastic strain. It could be used in structural health monitoring, for real-time monitoring of crack propagation or general evaluation of the condition of a structure, both visualized by a change in color. In this study, magnetostrictive polymer composites (MPCs) with Fe81Al19 (Alfenol) alloy particles are evaluated to determine magneto-elastic properties in composite patches attached to a surface, prior to understanding the full hybrid magneto–elasto–optical interactions. To measure static magneto-elastic performance, a tension apparatus within a solenoid was fabricated to apply uniform strain to the MPC patch on an aluminum dog-bone substrate. It was demonstrated that, for epoxies with an elastic modulus higher than ~0.1 GPa, a tensile strain/stress applied to the composite improved magneto-elastic coupling, resulting in increased permeability values, at least up to strains of 0.1%. Composites were fabricated with both spherical and flake-shaped powders, with flake-shaped powders exhibiting better magnetic responses than those with spherical morphology. Alfenol MPCs were also measured dynamically at ultrasonic frequencies, exhibiting comparable dynamic sensing performance to Galfenol at 120 kHz using ultrasonic guided wave techniques.
Non-Systematic Weighted Satisfiability in Discrete Hopfield Neural Network Using Binary Artificial Bee Colony Optimization
Authors: Muhammad Sidik Siti Syatirah , Zamri Nur Ezlin , Mohd Kasihmuddin Mohd Shareduwan , Wahab Habibah A. , Guo Yueling , Mansor Mohd. Asyraf
Published: April 2022

Recently, new variants of non-systematic satisfiability logic were proposed to govern Discrete Hopfield Neural Network. This new variant of satisfiability logical rule will provide flexibility and enhance the diversity of the neuron states in the Discrete Hopfield Neural Network. However, there is no systematic method to control and optimize the logical structure of non-systematic satisfiability. Additionally, the role of negative literals was neglected, reducing the expressivity of the information that the logical structure holds. This study proposed an additional optimization layer of Discrete Hopfield Neural Network called the logic phase that controls the distribution of negative literals in the logical structure. Hence, a new variant of non-systematic satisfiability named Weighted Random 2 Satisfiability was formulated. Thus, a proposed searching technique called the binary Artificial Bee Colony algorithm will ensure the correct distribution of the negative literals. It is worth mentioning that the binary Artificial Bee Colony has flexible and less free parameters where the modifications tackled on the objective function. Specifically, this study utilizes a binary Artificial Bee Colony algorithm by modifying the updating rule equation by using not and (NAND) logic gate operator. The performance of the binary Artificial Bee Colony will be compared with other variants of binary Artificial Bee Colony algorithms of different logic gate operators and conventional binary algorithms such as the Particle Swarm Optimization, Exhaustive Search, and Genetic Algorithm. The experimental results and comparison show that the proposed algorithm is compatible in finding the correct logical structure according to the initiate ratio of negative literal.
Proving Feasibility of a Docking Mission: A Contractor Programming Approach
Authors: Bourgois Auguste , Rohou Simon , Jaulin Luc , Rauh Andreas
Published: April 2022

Recent advances in computational power, algorithms, and sensors allow robots to perform complex and dangerous tasks, such as autonomous missions in space or underwater. Given the high operational costs, simulations are run beforehand to predict the possible outcomes of a mission. However, this approach is limited as it is based on parameter space discretization and therefore cannot be considered a proof of feasibility. To overcome this limitation, set-membership methods based on interval analysis, guaranteed integration, and contractor programming have proven their efficiency. Guaranteed integration algorithms can predict the possible trajectories of a system initialized in a given set in the form of tubes of trajectories. The contractor programming consists in removing the trajectories violating predefined constraints from a system’s tube of possible trajectories. Our contribution consists in merging both approaches to allow for the usage of differential constraints in a contractor programming framework. We illustrate our method through examples related to robotics. We also released an open-source implementation of our algorithm in a unified library for tubes, allowing one to combine it with other constraints and increase the number of possible applications.
Towards Describing Student Learning of Abstract Algebra: Insights into Learners’ Cognitive Processes from an Acceptance Survey
Authors: Veith Joaquin Marc , Bitzenbauer Philipp , Girnat Boris
Published: April 2022

In an earlier contribution to Mathematics, we presented a new teaching concept for abstract algebra in secondary school mathematics, and we discussed findings from mathematics education research indicating that our concept could be used as a promising resource to foster students’ algebraic thinking. In accordance with the Design-Based Research framework, the developed teaching concept is now being revised in several iteration steps and optimised towards student learning. This article reports on the results of the formative assessment of our new teaching concept in the laboratory setting with N=9 individual learners leveraging a research method from science education: The acceptance survey. The results of our study indicate that the instructional elements within our new teaching concept were well accepted by the students, but potential learning difficulties were also revealed. On the one hand, we discuss how the insights gained in learners’ cognitive processes when learning about abstract algebra with our new teaching concept can help to refine our teaching–learning sequence in the sense of Design-Based Research. On the other hand, our results may serve as a fruitful starting point for more in-depth theoretical characterization of secondary school students’ learning progression in abstract algebra.
Advancing Multidisciplinary STEM Education with Mathematics for Future-Ready Quantum Algorithmic Literacy
Authors: How Meng-Leong
Published: April 2022

The perception that mathematics is difficult has always persisted. Nevertheless, mathematics is such an essential component of STEM education. Quantum technologies are already having enormous effects on our society, with advantages seen across a broad variety of industries, including finance, aerospace, and energy. These innovations promise to transform our lives. Managers in the business and public sectors will need to learn quantum computing. Quantum algorithmic literacy may help increase mathematical understanding and enthusiasm. The current paper proposes that one possible approach is to present the information in a reasonably gentle but intelligible way, in order to excite individuals with the mathematics that they already know by extending them to acquiring quantum algorithmic literacy. A gentle introduction to the mathematics required to model quantum computing ideas, including linear transformations and matrix algebra, will be given. Quantum entanglement, linear transformations, quantum cryptography, and quantum teleportation will be used as examples to illustrate the usefulness of basic mathematical concepts in formulating quantum algorithms. These exemplars in quantum algorithmic literacy can help to invigorate people’s interest in mathematics. Additionally, a qualitative comparative analysis (QCA) framework is provided that teachers can utilize to determine which students to approach for remediation. This assists the teachers in dispelling any pupils’ uncertainty about mathematical concepts.
A Boundary Element Procedure for 3D Electromagnetic Transmission Problems with Large Conductivity
Authors: Ospino Portillo Jorge Eliécer , Maischak Matthias , Nezhi Zouhair
Published: April 2022

We consider the scattering of time-periodic electromagnetic fields by metallic obstacles, or the eddy current problem. In this interface problem, different sets of Maxwell equations must be solved both in the obstacle and outside it, while the tangential components of both electric and magnetic fields are continuous across the interface. We describe an asymptotic procedure, applied for large conductivity, which reflects the skin effect in metals. The key to our method is a special integral equation procedure for the exterior boundary value problems corresponding to perfect conductors. The asymptotic procedure leads to a great reduction in complexity for the numerical solution, since it involves solving only the exterior boundary value problems. Furthermore, we introduce a FEM/BEM coupling procedure for the transmission problem and consider the implementation of Galerkin’s elements for the perfect conductor problem, and present numerical experiments.
Performance of Dense Wireless Networks in 5G and beyond Using Stochastic Geometry
Authors: Aghazadeh Ayoubi Reza , Spagnolini Umberto
Published: April 2022

Device density in cellular networks is expected to increase considerably in the near future. Accordingly, the access point (AP) will be equipped with massive multiple-input multiple-output (mMIMO) antennas, using collimated millimeter-wave (mmW) and sub-THz communications, and increasing the bandwidth to accommodate the growing data rate demands. In this scenario, interference plays a critical role and, if not characterized and mitigated properly, might limit the performances of the network. In this context, this paper derives the statistical properties of the aggregated interference power for a cellular network equipping a mMIMO cylindrical array. The proposed statistical model considers the link blockage and other network parameters such as antenna configuration and device density. The findings show that the characteristic function (CF) of the aggregated interference power can be regarded as a weighted mixture of two alpha-stable distributions. Furthermore, by analyzing the service probability, it is found that there is an optimal configuration of the array depending on the AP height and device density. The proposed statistical model can be part of the design of dense networks providing valuable insights for optimal network deployment and resource management and scheduling.
Coherence Coefficient for Official Statistics
Authors: Krapavickaitė Danutė
Published: April 2022

One of the quality requirements in official statistics is coherence of statistical information across domains, in time, in national accounts, and internally. However, no measure of its strength is used. The concept of coherence is also met in signal processing, wave physics, and time series. In the current article, the definition of the coherence coefficient for a weakly stationary time series is recalled and discussed. The coherence coefficient is a correlation coefficient between two indicators in time indexed by the same frequency components of their Fourier transforms and shows a degree of synchronicity between the time series for each frequency. The usage of this coefficient is illustrated through the coherence and Granger causality analysis of a collection of numerical economic and social statistical indicators. The coherence coefficient matrix-based non-metric multidimensional scaling for visualization of the time series in the frequency domain is a newly suggested method. The aim of this article is to propose the use of this coherence coefficient and its applications in official statistics.
Fekete–Szegö Functional Problem for a Special Family of m-Fold Symmetric Bi-Univalent Functions
Authors: Swamy Sondekola Rudra , Frasin Basem Aref , Aldawish Ibtisam
Published: April 2022

In the current work, we introduce a special family of the function family of analytic and m-fold symmetric bi-univalent functions and obtain estimates of the Taylor–Maclaurin coefficients |dm+1| and |d2m+1| for functions in the special family. For δ a real number, Fekete–Szegö functional |d2m+1−δdm+12| for functions in the special family is also estimated. We indicate several cases of the defined family and connections to existing results are also discussed.
Strategically Altered Fluorinated Polymer at Nanoscale for Enhancing Proton Conduction and Power Generation from Salinity Gradient
Authors: Sharma Prem P. , Singh Rahul , Shah Syed Abdullah , Yoo Cheol Hun , Lee Albert S. , Kim Daejoong , Na Jeong-Geol , Lee Jong Suk
Published: April 2022

Reverse electrodialysis (RED) generates power directly by transforming salinity gradient into electrical energy. The ion transport properties of the ion-exchange membranes need to be investigated deeply to improve the limiting efficiencies of the RED. The interaction between “counterions” and “ionic species” in the membrane requires a fundamental understanding of the phase separation process. Here, we report on sulfonated poly(vinylidene fluoride-co-hexafluoropropylene)/graphitic carbon nitride nanocomposites for RED application. We demonstrate that the rearrangement of the hydrophilic and hydrophobic domains in the semicrystalline polymer at a nanoscale level improves ion conduction. The rearrangement of the ionic species in polymer and “the functionalized nanosheet with ionic species” enhances the proton conduction in the hybrid membrane without a change in the structural integrity of the membrane. A detailed discussion has been provided on the membrane nanostructure, chemical configuration, structural robustness, surface morphology, and ion transport properties of the prepared hybrid membrane. Furthermore, the RED device was fabricated by combining synthesized cation exchange membrane with commercially available anion exchange membrane, NEOSEPTA, and a maximum power density of 0.2 W m−2 was successfully achieved under varying flow rates at the ambient condition.
Electrospun Hybrid Films for Fast and Convenient Delivery of Active Herb Extracts
Authors: Guo Shiri , Jiang Wenlai , Shen Liangfei , Zhang Gaoyi , Gao Yiman , Yang Yaoyao , Yu Deng-Guang
Published: April 2022

Herb medicines are popular for safe application due to being a source of natural herbs. However, how to deliver them in an efficacious and convenient manner poses a big challenge to researchers. In this study, a new concept is demonstrated that the electrospun polymer-based hybrid films can be a platform for promoting the delivery of a mixture of active herb extract, i.e., Lianhua Qingwen Keli (LQK), also a commercial traditional Chinese patent medicine. The LQK can be co-dissolved with the filament-forming polymeric polyvinylpyrrolidone K60 and a sweeter sucralose to prepare an electrospinnable solution. A handheld electrospinning apparatus was explored to transfer the solution into solid nanofibers, i.e., the LQK-loaded medicated films. These films were demonstrated to be composed of linear nanofibers. A puncher was utilized to transfer the mat into circular membrane a diameter of 15 mm. Two self-created methods were developed for disclosing the dissolution performances of the electrospun mats. Both the water droplet experiments and the wet paper (mimic tongue) experiments verified that the hybrid films can rapidly disintegrate when they encounter water and release the loaded LQK in an immediate manner. Based on the reasonable selections of polymeric excipients, the present protocols pave a way for delivering many types of active herb extracts in an effective and convenient manner.
Moving beyond 90% Carbon Capture by Highly Selective Membrane Processes
Authors: Han Yang , Ho W. S. Winston
Published: April 2022

A membrane-based system with a retentate recycle process in tandem with an enriching cascade was studied for >90% carbon capture from coal flue gas. A highly CO2-selective facilitated transport membrane (FTM) was utilized particularly to enhance the CO2 separation efficiency from the CO2-lean gases for a high capture degree. A techno-economic analysis showed that the retentate recycle process was advantageous for ≤90% capture owing to the reduced parasitic energy consumption and membrane area. At >90% capture, the enriching cascade outperformed the retentate recycle process since a higher feed-to-permeate pressure ratio could be applied. An overall 99% capture degree could be achieved by combining the two processes, which yielded a low capture cost of USD47.2/tonne, whereas that would be USD 42.0/tonne for 90% capture. This FTM-based approach for deep carbon capture and storage can direct air capture for the mitigation of carbon emissions in the energy sector.
Study on the Effect of Microstructure Gradients Caused by Heat Gradients on Hydrogen Embrittlement Sensitivity in Heavy Forgings
Authors: Li Lingxiao , Liu Jiyan , Wang Yuhao , Zhang Guozhu , Du Fengshan
Published: April 2022

The hydrogen embrittlement problem of alloy steel heavy forgings not only has the common properties of general hydrogen embrittlement, but also has the characteristics brought by its scale characteristics. The research of hydrogen embrittlement, combined with its characteristics and commonness, is of vital importance for the service safety of engineering structures. The temperature field and microstructure distribution in the machining process were investigated through the simulation of a finite element. On this basis, the physical simulation experiments were carried out to obtain the microstructure of heavy forgings in radial directions. The hydrogen embrittlement sensitivity was characterized by electrochemical hydrogen charging and slow strain rate tests (SSRT). The microstructure and fracture morphology of the samples were characterized to explore the law and mechanism of hydrogen embrittlement sensitivity gradient distribution along the axial direction. It is helpful to understand the hydrogen embrittlement of heavy forgings in order to guide engineering practice.
Laser Preheating for Hot Crack Reduction in Direct Metal Deposition of Inconel 738LC
Authors: Soffel Fabian , Papis Konrad , Bambach Markus , Wegener Konrad
Published: April 2022

Welding of precipitation-hardenable nickel-based super alloys that contain large amounts of Al and Ti is challenging due to their high susceptibility to hot cracking. For metal additive manufacturing (AM) by powder bed fusion (PBF) or direct metal deposition (DMD), various welding process adjustments may prevent the formation of cracks. The aim of this study is the development and experimental characterization of a laser preheating process for DMD of Inconel 738LC. Metallographic cross-sections of multiple test specimens were analyzed to quantify the effect of initial substrate temperature, specimen geometry, deposition parameters, and scanning strategy on the resulting crack density. The results show that increased substrate temperature by laser preheating and reduced specimen size leads to crack-free deposited structures. Therefore, the proposed preheating process may be applied for part fabrication or repair by DMD to reduce or even completely prevent the risk of hot cracking.
Fatigue Crack Initiation and Propagation Relation of Notched Specimens with Welded Joint Characteristics
Authors: Braun Moritz , Fischer Claas , Baumgartner Jörg , Hecht Matthias , Varfolomeev Igor
Published: April 2022

This study focuses on predicting the fatigue life of notched specimens with geometries and microstructure representative of welded joints. It employs 26 series of fatigue tests on welded and non-welded specimens containing notches located in different material zones, including the parent material, weld metal, and heat-affected zone. Overall, 351 test samples made of six structural steels are included in the present evaluation. For each individual specimen, the stress concentration factor, as well as the stress distribution in the notched section, was determined for subsequent fracture mechanics calculation. The latter is employed to estimate the fraction of fatigue life associated with crack propagation, starting from a small surface crack until fracture. It was shown that the total fatigue life can be realistically predicted by means of fracture mechanics calculations, whereas estimates of the fatigue life until macroscopic crack initiation are subject to numerous uncertainties. Furthermore, methods of statistical data analyses are applied to explore correlations between the S–N curves and the notch acuity characterized by the notch radius, opening angle, and the stress concentration factor. In particular, a strong correlation is observed between the notch acuity and the slope of the S–N curves.
Initiation Behavior of Microscopic Short Cracks in Weld Toe of Structural Steel Q345B
Authors: Cheng Lifu , Chen Xinyuan , Wei Guoqian , Ye Fan
Published: April 2022

Aiming at the base metal (BM) zone, heat affected zone (HAZ) and fusion zone (FZ) of the weld, the tip plastic zone and initiation behavior of microscopic short cracks (MSCs) in the toe of cross-welded joints are studied. Based on the theory of crack tip plastic zone and the fatigue index parameter (FIP), the shape and boundary size of the plastic zone at the tip of MSCs as well as the initiation life were calculated. The results show that the plastic zone was bone-like under plane stress and butterfly-like under plane stress; when the crack length increased from 2 μm to 30 μm, the boundary size of the plastic zone at the MSC tip increased by 15 μm and 2 μm under the action of plane stress and plane strain in the X-axis direction, respectively. As the grain gradient decreased from 0.5 to 0.1, the boundary size of the plastic zone at the tip of the MSC increased about 50%. MSC initiation occurs first in the BM zone, and life of initiation was about several hundred thousand cycles, which was consistent with the experimental result. The MSC expansion rate in BM zone was the fastest, with the average expansion rate about 2.5 × 10−3 μm/cycle; the MSC expansion rate in the FZ and HAZ was about 3.1 × 10−4 μm/cycle.
Rewiring of the Liver Transcriptome across Multiple Time-Scales Is Associated with the Weight Loss-Independent Resolution of NAFLD Following RYGB
Authors: Lei Peng , Chukwudi Chijioke , Pannu Prabh R. , He Shijie , Saeidi Nima
Published: April 2022

Roux-en-Y gastric bypass (RYGB) surgery potently improves obesity and a myriad of obesity-associated co-morbidities including type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). Time-series omics data are increasingly being utilized to provide insight into the mechanistic underpinnings that correspond to metabolic adaptations in RYGB. However, the conventional computational biology methods used to interpret these temporal multi-dimensional datasets have been generally limited to pathway enrichment analysis (PEA) of isolated pair-wise comparisons based on either experimental condition or time point, neither of which adequately capture responses to perturbations that span multiple time scales. To address this, we have developed a novel graph network-based analysis workflow designed to identify modules enriched with biomolecules that share common dynamic profiles, where the network is constructed from all known biological interactions available through the Kyoto Encyclopedia of Genes and Genomes (KEGG) resource. This methodology was applied to time-series RNAseq transcriptomics data collected on rodent liver samples following RYGB, and those of sham-operated and weight-matched control groups, to elucidate the molecular pathways involved in the improvement of as NAFLD. We report several network modules exhibiting a statistically significant enrichment of genes whose expression trends capture acute-phase as well as long term physiological responses to RYGB in a single analysis. Of note, we found the HIF1 and P53 signaling cascades to be associated with the immediate and the long-term response to RYGB, respectively. The discovery of less intuitive network modules that may have gone overlooked with conventional PEA techniques provides a framework for identifying novel drug targets for NAFLD and other metabolic syndrome co-morbidities.
Metabolites Concentration in Plasma and Heart Tissue in Relation to High Sensitive Cardiac Troponin T Level in Septic Shock Pigs
Authors: Bollen Pinto Bernardo , Ferrario Manuela , Herpain Antoine , Brunelli Laura , Bendjelid Karim , Carrara Marta , Pastorelli Roberta
Published: April 2022

Elevated circulating cardiac troponin T (cTnT) is frequent in septic shock patients. Signs of myocardial ischemia and myocyte necrosis are not universally present, but the precise mechanism for elevated cTnT is unknown. We investigated plasma and heart tissue metabolites concentration in six septic shock (SS) and three sham swine undergoing a protocol of polymicrobial septic shock and resuscitation, in order to highlight possible pathways and biomarkers involved in troponin release (high sensitive cardiac troponin T, hs-cTnT). The animals were divided into two groups: the high cTnT group (n = 3) were pigs showing a significantly higher concentration of cTnT and lactate after resuscitation; the low cTnT group (n = 6, three sham and three septic shock) characterized by a lower value of cTnT and a lactate level < 2 mmol/L. Spearman correlation was assessed on plasma fold-change of cTnT, cytokines (TNF-α and IL-10), and metabolites. Finally, the fold-change between the end of resuscitation and baseline values (Res./BL) of plasma metabolites was used to perform a partial least square discriminant analysis (PLS-DA) with three latent variables. Before building the model, the number of features was reduced by summing up the metabolites of the same class that resulted similarly correlated to cTnT fold-change. Proline and glycine were significantly higher in the high cTnT group at the end of experiment both in the myocardium and plasma analyses. Moreover, plasma proline fold-change was found to be positively correlated with cTnT and cytokine fold-changes, and trans-4-hydroxyproline (t4-OH-Pro) fold-change was positively correlated with cTnT fold-change. The PLS-DA model was able to separate the two groups and, among the first ranked features based on VIP score, we found sugars, t4-OH-Pro, proline, creatinine, total amount of sphingomyelins, and glycine. Proline, t4-OH-Pro, and glycine are very abundant in collagen, and our results may suggest that collagen degradation could represent a possible mechanism contributing to septic myocardial injury. The common phenotype of septic cardiomyopathy could be associated to dysregulated collagen metabolism and/or degradation, further exacerbated by higher inflammation and oxidative stress.
Plasma Lipid Profiles Change with Increasing Numbers of Mild Traumatic Brain Injuries in Rats
Authors: Anyaegbu Chidozie C. , Szemray Harrison , Hellewell Sarah C. , Lawler Nathan G. , Leggett Kerry , Bartlett Carole , Lins Brittney , McGonigle Terence , Papini Melissa , Anderton Ryan S. , Whiley Luke , Fitzgerald Melinda
Published: April 2022

Mild traumatic brain injury (mTBI) causes structural, cellular and biochemical alterations which are difficult to detect in the brain and may persist chronically following single or repeated injury. Lipids are abundant in the brain and readily cross the blood-brain barrier, suggesting that lipidomic analysis of blood samples may provide valuable insight into the neuropathological state. This study used liquid chromatography-mass spectrometry (LC-MS) to examine plasma lipid concentrations at 11 days following sham (no injury), one (1×) or two (2×) mTBI in rats. Eighteen lipid species were identified that distinguished between sham, 1× and 2× mTBI. Three distinct patterns were found: (1) lipids that were altered significantly in concentration after either 1× or 2× F mTBI: cholesterol ester CE (14:0) (increased), phosphoserine PS (14:0/18:2) and hexosylceramide HCER (d18:0/26:0) (decreased), phosphoinositol PI(16:0/18:2) (increased with 1×, decreased with 2× mTBI); (2) lipids that were altered in response to 1× mTBI only: free fatty acid FFA (18:3 and 20:3) (increased); (3) lipids that were altered in response to 2× mTBI only: HCER (22:0), phosphoethanolamine PE (P-18:1/20:4 and P-18:0/20:1) (increased), lysophosphatidylethanolamine LPE (20:1), phosphocholine PC (20:0/22:4), PI (18:1/18:2 and 20:0/18:2) (decreased). These findings suggest that increasing numbers of mTBI induce a range of changes dependent upon the lipid species, which likely reflect a balance of damage and reparative responses.
Fluoride Metabolism in Pregnant Women: A Narrative Review of the Literature
Authors: Castiblanco-Rubio Gina A. , Martinez-Mier E. Angeles
Published: April 2022

Epidemiological studies use biomarkers of fluoride exposure in pregnant women as surrogate measures of fetal fluoride exposure; however, there is little understanding of how pregnancy affects fluoride metabolism and its biomarkers. This narrative review summarizes the changes of pregnancy that have the potential to impact fluoride’s absorption, distribution and excretion, and highlights the limited body of evidence on the topic. The physiologic systems that experience pregnancy-associated changes relevant to fluoride’s metabolism are the cardiovascular, renal, metabolic and gastrointestinal, as well bone and calcium metabolism and the body’s acid-base balance. The available evidence indicates that fluoride is found in the maternal plasma and urine, placenta, amniotic fluid and fetus. Although plasma and urinary fluoride vary across gestation, there is insufficient quality evidence to determine the direction or extent of such variation. Furthermore, there is no doubt that fluoride from maternal blood crosses the placenta and is absorbed and excreted by the fetus; however, the biological mechanisms behind this placental passage are unknown. Research on maternal and prenatal biomarkers of fluoride exposure would benefit from studies on how pregnancy-associated changes affect the metabolism of fluoride across gestation, the mechanisms for the intestinal absorption of fluoride in pregnant women, and the placental passage of fluoride.
Bacterial Communities of Forest Soils along Different Elevations: Diversity, Structure, and Functional Composition with Potential Impacts on CO2 Emission
Authors: Sun Wanlong , Li Zhouyuan , Lei Jiesi , Liu Xuehua
Published: April 2022

Soil bacteria are important components of forest ecosystems, there compostion structure and functions are sensitive to environmental conditions along elevation gradients. Using 16S rRNA gene amplicon sequencing followed by FAPROTAX function prediction, we examined the diversity, composition, and functional potentials of soil bacterial communities at three sites at elevations of 1400 m, 1600 m, and 2200 m in a temperate forest. We showed that microbial taxonomic composition did not change with elevation (p = 0.311), though soil bacterial α-diversities did. Proteobacteria, Acidobacteria, Actinobacteria, and Verrucomicrobia were abundant phyla in almost all soil samples, while Nitrospirae, closely associated with soil nitrogen cycling, was the fourth most abundant phylum in soils at 2200 m. Chemoheterotrophy and aerobic chemoheterotrophy were the two most abundant functions performed in soils at 1400 m and 1600 m, while nitrification (25.59% on average) and aerobic nitrite oxidation (19.38% on average) were higher in soils at 2200 m. Soil CO2 effluxes decreased (p < 0.050) with increasing elevation, while they were positively correlated (r = 0.55, p = 0.035) with the abundances of bacterial functional groups associated with carbon degradation. Moreover, bacterial functional composition, rather than taxonomic composition, was significantly associated with soil CO2 effluxes, suggesting a decoupling of taxonomy and function, with the latter being a better predictor of ecosystem functions. Annual temperature, annual precipitation, and pH shaped (p < 0.050) both bacterial taxonomic and functional communities. By establishing linkages between bacterial taxonomic communities, abundances of bacterial functional groups, and soil CO2 fluxes, we provide novel insights into how soil bacterial communities could serve as potential proxies of ecosystem functions.
Tropheryma whipplei, Helicobacter pylori, and Intestinal Protozoal Co-Infections in Italian and Immigrant Populations: A Cross-Sectional Study
Authors: Moro Lucia , Pomari Elena , Leonardi Martina , La Marca Giulia , Pajola Barbara , Mazzi Cristina , Piubelli Chiara , Beltrame Anna
Published: April 2022

Tropheryma whipplei (TW), Helicobacter pylori (HP), and intestinal protozoa (IP) are widespread pathogens with similar routes of transmission and epidemiological risk factors. Epidemiological data on co-infection between TW, HP, and IP are scarce. We aim to more deeply investigate the co-infection rate for these pathogens, evaluating the risk factors and symptoms. Methods: This is a cross-sectional study conducted at the IRCCS Sacro Cuore Don Calabria Hospital in Northern Italy, a referral center for tropical and Whipple’s disease (WD). Stored stool samples from 143 subjects previously tested for TW DNA by real-time PCR were explored for HP and IP DNA detection. The virulence factor cagA was investigated in HP-positive patients. Results: A history of migration was reported significantly more in TW-positive than in negative subjects (34.1% vs. 9.1%, p = 0.001) and in HP-infected than in those non-infected (59.1% vs. 9.1%, p < 0.001). The HP infection rate differed significantly between TW-infected and uninfected groups (31.8% vs. 8.1%, p = 0.001), while no difference was observed for IP infection. Significantly higher TW intestinal colonization was found in HP-infected patients than in non-infected (63.6% vs. 24.8%, p < 0.001). In addition, the proportion of Blastocysts positive finding was also significantly higher in HP-infected than in non-infected (40.9% vs. 17.4%, p = 0.018). Conclusions: The present study is the first to report a high TW and HP co-infection rate. To reduce the risk of morbidity from a chronic infection of either pathogen, clinicians may consider TW-HP molecular screening on the same stool sample for patients with suspected HP disease or WD, particularly in case of travel history.