bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Pulverised Method on the Plasticity and Strength Behaviour of Cement Stabilised Clayshale and Sandstone
Authors: Hartono E , Muntohar A S , Abiyoga N P
Published: May 2021

Clayshale and sandstone are types of sediment that generally have a contrast soil behaviour. Clayshales, however, is less durable due to the hydrosphere and atmospheric exposure, but a sandstone has low strength in loose condition. The present research is to investigate the effectiveness of dry and spray pulverised method on cement-stabilised clayshale and sandstone. The cement content ranged from 2% to 10% by the dry weight of soil. The unconfined compression strength test was performed on cement-stabilised soil. Atterberg limit test was also performed to evaluate the soil modification due to stabilisation. The results show that cement reduced the liquid limit and increased the plastic limit, which caused a decrement on the plasticity index. As the cement content increased, the unconfined compression strength of clayshale and sandstone also significantly increased. This study has shown that the unconfined compressive strength with the pulverised spray method is higher than that of the dry pulverised method. The secant modulus made using dry pulverised method is higher than the pulverised spray method. The dry pulverised process generates specimens with more brittle behaviour than the spray-pulverised method, based on the study of damage property by using energy dissipation.
A Study on Durability for Rigid Pavement Against Acid Environment and Displacement Model
Authors: Widodo Wahyu
Published: May 2021

An acidic environment commonly found in peat soils or expansive soil will harm the quality of rigid pavement by considering its use at long-life plan, traffic load, and minimization of damage to the crossroad due to vehicle braking. As a concrete provider, chemical admixture as mixed materials today is widely used with the reasons of workability, initial strength, as well as saving of material used. This research aimed to find out the durability of concrete admixture using sika-NN and plastocrete (retarding and water reducing admixture) at the acid environment and knowing the displacement that occurred using ABAQUS software modeling. It used the laboratory experimental method and the cube concrete sample 15×15×15 cm with the compressive strength of 33.2 MPa. A total of 18 concrete samples were immersed using normal pH water and H2SO4 at pH 1 ± 1 tested at 3, 7, 14, 28, 60, and 90 days using the Duplo method. In this research, the concrete durability was carried out using, Ultrasonic Pulse Velocity Test (UPVT) to test the density, compressive test, and modeling concrete displacement on peat soils with vehicle loads in acidic environments using software ABAQUS. The mixed design results show an average setting time value of about 112 minutes. Coarse aggregate and cement decrease due to additives is approximately 24% and 18% respectively, increasing the use of fine aggregate to 16.49%, but the value of concrete density increases base on soaking time. Besides that, there is a decrease in compressive strength up to 16% at the age of 90 days. The value of displacement in the modelled pavement uses a maximum load of 8 tons each 2.994 mm for concrete with normal water and 3.045 mm for concrete with an acid environment respectively. Concrete soaked in acid water is the greatest deformation that occurred in rigid pavement using ABAQUS and indicates that acid water has an impact on decreasing concrete quality.
Traffic Detection Program using Image Processing and the 1997 Indonesian Highway Capacity Manual (MKJI)
Authors: Muchlisin M , Wijayanti F A , Amanda N
Published: May 2021

As a part of transport planning and assessment, traffic volume is essential data. However, many Indonesian’s transports engineers, in particular, still use manual traffic counting to collect data series for traffic volume in 24 hours or more. This method is considered inefficient and expensive along with technological developments in this modern era. The purpose of this study tries to simplify the traffic counting method by developing an automatic vehicle detection program based on the 1997 Indonesian Highway Capacity Manual (MKJI) classification. The application that used in this study is KS Traffic Analyzer as open-source code traffic counting based on Java and OpenCV library. This application then modifies as MKJI 1997 vehicles classification to measure traffic data in urban and rural road using drone quadcopter. This tool using Gaussian Mixture Model (GMM) method for processing images/videos of traffic based on the background and foreground. Traffic footage was tested at different times, height, and angle of shooting. The accuracy was measured by comparing the volume from the program and manual counting. The results showed that the best accuracy between real traffic volume and automatic counting in the program is in the urban street with the best accuracy reached 93.66% which was taken video in the morning and the height is 5 m. This result of this study also answers the function of road performance based on volume per capacity.
Improvement of the properties of additively manufactured steel parts by combination of heat treatment and hard coatings
Authors: Frank H , Ambos M , Lutze S , Scholz M
Published: May 2021

In additive manufacturing using SLM (selective laser melting), the maraging steel 1.2709 is often used to produce metallic components for various applications. The work piece properties depend on the process control in the additive process, but also on the heat treatment and the final processing. Here, the heat treatment and the used finishing processes lead to changes in the work piece and material properties (e.g. residual stresses, strength). As part of the international “Ad-Proc-Add” project, the presented work took into account individual process steps of the process chain with consideration of: additive manufacturing - pre-treatment - functionalization - final processing when using different materials. In investigations of additive manufacturing of the material 1.2709, it could be proven that the thermal treatment determines the mechanical properties of the components. A PVD coating process was used to replace the usual heat treatment. Similar temperature-time regimes during the coating resulted in mechanical properties comparable to conventionally heat-treated additively manufactured components. In addition to modifying the microstructure and the component properties, the PVD coatings improve the surface wear resistance up to more than 60%. Further investigations to improve the adhesion strength of the coatings are planned.
Process-related influences and correlations in wire arc additive manufacturing of high-strength steels
Authors: Schroepfer D , Scharf-Wildenhain R , Haelsig A , Wandtke K , Kromm A , Kannengiesser T
Published: May 2021

High-strength fine-grained structural steels have great potential for weight-optimized, efficient structures in many modern steel applications. Further advances in efficiency can be achieved through additive manufacturing and bionic design. Commercial high-strength filler materials for wire arc additive manufacturing (WAAM) are already provided by the consumable producers. Today, application would be strictly limited due to absence of quantitative findings or any guidelines for the industry regarding welding-related stresses and component safety during manufacturing and service. Hence, process- and material-related influences and design-related restraint conditions associated with formation of residual stresses and cold cracking risk are investigated. The aim is the accessibility of special WAAM self-restraining cold cracking tests and easy applicable processing recommendations, enabling an economical, fit-for-purpose and crack-safe WAAM of high-strength steels. This first study focuses on determination of interactions between WAAM process parameters, resulting layer geometry, microstructure and residual stresses, analyzed via X-ray diffraction. Defined reference specimens are automated welded using a special WAAM solid wire (yield strength >820 MPa). Geometric properties can be specifically adjusted by wire feed and welding speed, but cannot be varied arbitrarily, since a high heat input causes local overheating, inadmissible changes of microstructure and mechanical properties, defects and comparable high tensile residual stresses.
Mathematical modeling and simulation of the dissolution of zinc anodes in industrial electroplating
Authors: Schwöbel S D , Meinhold V , Mehner T , Lampke T
Published: May 2021

The simulation of large-scale industrial electrodeposition of zinc is of major importance, since through the simulation, important data about the positioning of electrodes, thickness of layers, etc. can be generated. But the models used in practical applications indirectly assume small anodes and cathodes for which the electrical potential or the charge-transfer current are constant over the cathode, resp. anode. In this paper, a new type of model for the dissolution of zinc anodes is described. Furthermore, a numerical scheme to treat the model will be described and verified. The new model will be compared to a commonly known model. The paper gives an alternative model for the calculation of the current density on anodes and formulates a FEM for the approximation of Poisson equations on multiple domains with Robin-interfaces. Besides the application to the dissolution of zinc-anodes during electro-plating, the basic model and FEM can be applied to the dissolution of anodes made of a different material and to the modelling of corrosion processes.
Electrical contacting of High-Velocity-Air-Fuel sprayed NiCr20 coatings by brazing
Authors: Bobzin K , Wietheger W , Heinemann H , Liao X , Vogels C
Published: May 2021

Thermally sprayed heater coatings can be used to control the surface temperature of parts and tools. A crucial point for such applications that has been neglected in the past is a reliable electrical contact with the power supply. One possible solution is the soldering or brazing of cables and cable connectors onto the heater coating. In this study, the possibility of brazing cable connectors to High-Velocity-Air-Fuel sprayed NiCr20 coatings was investigated to ensure electrical contact. The eutectic Ag-Cu filler was used for the vacuum brazing process. The insufficient wetting of the filler on the as-sprayed coating surface and the favored wetting of this filler on the copper cable connector led to low joint quality. This joint was improved by grinding the coating surface and changing the cable connector’s material. Furthermore, measurements of the heater coatings’ electrical resistance confirmed that electrical contacting by brazing is possible without significant influence on the heater coatings’ properties.
Feasibility, processing properties and thermal behavior of Ni nanopastes produced by ultrasound-enhanced dispersing
Authors: Sattler B , Hausner S , Wagner G
Published: May 2021

Nickel nanoparticles are materials that can be used for a novel type of joining, so called nanojoining, as an alternative to conventional brazing. The physical characteristics of these nano-sized particles lead to a lower melting temperature compared to nickel bulk material and even lower than typical brazes, without the need for melting point depressants. Such elements like boron or silicon cause issues due to formation of brittle intermetallic phases. In order to be able to use Ni nanoparticles in practical applications, they have to be in forms such as suspensions, e.g pastes. In the present work, therefore, a series of Ni nanopastes is prepared and investigated with emphasis on the solvent systems. These suspensions consist of Ni nanoparticles (mean diameter 20 / 90 / 180 / 300 nm) and organic compounds. The examinations show the feasibility of producing such nanopastes using ultrasound-enhanced dispersing, as well as margins for adjusting their processing properties. In addition, first results of the thermal behavior of the Ni nanopastes, measured by simultaneous DSC/TG, are shown.
Effect of sample geometry on the macroscopic shear deformation of the titanium alloy Ti-10V-2Fe-3Al subjected to quasi-static and dynamic compression-shear loading
Authors: Winter S , Scholze M , Wagner M F-X
Published: May 2021

We investigate the evolution of shear bands in a Ti-10V-3Fe-2Al alloy with three different initial microstructures: solution-annealed β-titanium, β-titanium with primary α-phase precipitates as well as a condition with primary and secondary α-phase precipitates. Quasi-static and dynamic testing of compression-shear specimens with strain rates of 10-3 s-1 and 102 s-1 is performed at room temperature. The influence of two different sample geometries on the macroscopic shearing tendency is investigated: samples with a cylindrical cross section and samples with a square cross section. The results of digital image correlation and the nominal stress-strain behavior under quasi-static and dynamic loading indicate a stronger localization tendency of the aged conditions with additional α-phase precipitates compared to the solution-annealed pure β-condition. Our results also demonstrate that compression-shear testing with samples with a square cross-section reduces facet loss, increases the resolution even at high strain rates and therefore allows to analyze strain distributions during shear band formation and propagation with higher accuracy.
Chemical structure of amino-terminated alkyl silanes influencing the strength of aluminum-polyamide joints
Authors: Dittes A , Scharf I , Lehmann L , Saborowski E , Mehner T , Lampke T
Published: May 2021

Organo-functional silane coupling agents are widely used to promote adhesion in between inorganic and organic materials. Amino-functional silanes can improve bonding with polyamide. Aiming on a mechanically performant aluminum-polyamide joints, the effect of six amino silanes of different chemical structure, namely number and type of amine groups and alkyl spacers lengths, on the joint strength is investigated by means of lap-shear testing. Higher shear strengths are found along with a more pronounced capability of the amine group to form hydrogen bonds with polyamide. The results show that an additional amine group within the organo-functional group can increase joint strength, whereas long alkyl spacers reduce the observed joint strength. It is shown that high lap-shear strengths, in maximum about 15 MPa for N-(2-aminoethyl)-3-aminopropyltrimethoxysilane are achieved and that the high reproducibility can be assured when using right processing routines.
Effect of local reinforcement particle distribution on mechanical properties of in-situ TiB/TiC1-x particle reinforced Ti-5Al-5Mo-5V-3Cr – comparison between model and experiment
Authors: Grützner S , Krüger L , Schneider I
Published: May 2021

In-situ TiB and TiC1-x particle-reinforced titanium matrix composites (TMCs) based on a near-β Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) reacting chemically with 4 vol.-% B4C were processed by spark plasma sintering (SPS). Different local distributions of the reinforcement particles formed within the composite were adjusted by varying the conditions during powder preparation. The measured Young’s modulus, hardness and compressive yield strength of the composites increased, as the reinforcement particles were distributed more homogeneously within the matrix. In addition, Young’s modulus and hardness were modelled considering the hybrid TiB-whisker and TiC-particle reinforcement applying the rule of hybrid mixtures (RoHM) and the Fu-method, respectively. The compressive yield strength was modelled in ac-cordance with the summation of the particular effective strengthening mechanisms and the Clyne-method. Measured values of the Young’s modulus and the hardness were overestimated by the modelling as the clustering of the reinforcement particles increased. The compressive yield strength of the composites is modelled appropriately using the Clyne-method. However, pronounced agglomeration of the reinforcing particles within the matrix resulted in an overesti-mation of the measured values.
Prediction of residual-stress depth profiles in turning of EN AW-2017 based on in-process measurements of machining forces and temperatures
Authors: Mehner T , Junge T , Schubert A , Lampke T
Published: May 2021

The surface integrity of parts is strongly impacted by the surface-layer properties, which are modified by machining processes. In particular, it is advantageous if the finish machining process generates a resilient residual-stress state without additional post-treatment. Thus, this paper describes relationships between the forces and temperature which are measured in-situ/during the process and the residual-stress profile for the turning of the aluminum alloy EN AW-2017. The residual-stress depth profiles are measured by X-ray diffraction after electrochemical removal of material by means of jet-electrochemical machining. The characteristic features of the residual-stress profile (value and depth under the surface of the local minimum of the residual stress) are determined and modeled using multiple regression. The predictions of the models are validated by test samples. An excellent agreement between experiments and the model is achieved. Thus, the models can be applied to predict the expected residual-stress profiles during the machining process, which allows for an in-process adjustment of the machining parameters in order to generate an advantageous residual-stress state.
Influence of metal matrix powder size on the tensile strength of a SiCp/AlSi7Mg0,6 composite produced by field assisted sintering technique
Authors: Pippig R , Hirsch S J , Grund T , Lampke T
Published: May 2021

In the present study, 35vol% SiCp/AlSi7Mg0,6 composites were prepared using field assisted sintering technique in order to investigate the effect of different particle fractions and size distributions of the AlSi7Mg matrix powder on the tensile properties of the produced composite material. In most usecases the size of the reinforcement phase is given by the application and is only variable within narrow limits (< 20pm particle size in this work). On the other hand, there is potential for optimization of the matrix powder. In this investigation, fine (d50
= 25 µm), coarse (d50
= 52 µm), bimodal (50wt% of fine + 50wt% of coarse, d50
= 36 µm) and as received (d50
= 40 µm) aluminum powder was used as the matrix powder. Using fine matrix powder has improved yield strength by 5 % and ultimate tensile strength by 7 % compared to the as received condition. This is largely due to the lower porosity of the composite produced under the use of the fine matrix powder ((0.07 ± 0.04) %) in contrast to the composite using the as received aluminum powder ((0.62 ± 0.35) %). At the same time, the consumed heating energy of the composite was decreased by almost a third when using the fine matrix powder in comparison to the use of the as-received matrix powder. This paper presents results of an optimization approach for mechanical properties of aluminum matrix composites without any changes of the sintering parameters.
Suitability of roughness parameters for the interlaminar strength prediction of mechanically interlocked polymer-metal-interfaces
Authors: Saborowski E , Steinert P , Dittes A , Lindner T , Schubert A , Lampke T
Published: May 2021

The interlaminar strength of mechanically interlocked polymer-metal-interfaces strongly depends on the metal surface topography. Hence, this contribution assesses standardized surface roughness parameters as well as fractal dimension for interlaminar strength prediction of EN AW-6082/polyamide 6 polymer-metal-hybrids. Seven different metal surface topographies generated by mechanical blasting, alkaline etching, thermal spraying as well as laser structuring are investigated. Interlaminar strength testing is carried out with regard to tensile and shear strength using butt-bonded hollow cylinder specimens. The surface roughness profiles are recorded with a tactile stylus profiler. The fractal dimension of the metal surface is derived from cross-sectional images. The measured interlaminar strength values show good correlation to the fractal dimension, moderate correlation to the root mean square slope of the surface roughness profile and no correlation to surface roughness height parameters.
Hybrid casting – An investigation into the interface of high-pressure die-cast intrinsic aluminum-PEEK-CFRP hybrid composites
Authors: Schmid A , Haubold T , Koschek K , Marx A , Pursche L , Struß A , Thiel K , Wiesing M , Busse M
Published: May 2021

The joining of plastic-based fiber composites and light metals is increasingly becoming the focus of lightweight construction applications. To date, conventional mechanical and adhesive joining techniques are still the predominant means to produce hybrid composites. The aim of this work was to create a hybrid composite of CFRP and aluminum in a novel way using the economic high-pressure die-casting process without the use of additional joining elements. The casting process implies the direct contact of molten metal (AlSi10MnMg) and thermally resistant polyetheretherketone (PEEK) under short-term temperatures of about 700 °C. The material and process parameters lead to a material transition that spatially separates the CFRP and the aluminum while guaranteeing a firm bond with lap shear strengths up to 22 MPa. This work structurally and chemically characterizes the interface between Al and PEEK in the hybrid composite. The results of the TEM investigations into the boundary region between PEEK and the AlSi10MnMg alloy show that both materials are locally joined without gaps. Furthermore, the chemical EDX, XPS and IR spectroscopy results indicate a tendency for the bond to form through the thermal alteration of the polymer and the associated modification of the bonding possibilities in the direct contact area.
Influence of EDM generator programs on shape and surface roughness of Ni-Ti sheets
Authors: Berger T , Martin A , Navickaité K , Schubert A
Published: May 2021

In the last decades caloric cooling technologies received an increasing scientific and industrial interest as promising alternatives to conventional vapor compression technology. Theoretically, efficiency of caloric technologies is more than 40% higher than for the conventional vapor compression cycle. Particularly interesting is elastocaloric cooling, which is an emerging technology, occurring due to the uniaxial mechanical loading of active regenerators. These are made of shape memory alloys, such as Ni-Ti. The regenerators must have a high fatigue resistance to withstand multiple loading cycles and simultaneously possess excellent elastocaloric properties. Therefore, it is crucial to establish a manufacturing process that allows fabricating thin regenerator elements with profound surface quality and as little impact on their functionality as possible. Considering the challenges of conventional machining technologies due to the specific characteristics of Ni-Ti, electrical discharge machining (EDM) demonstrates a high potential to meet the requirements for micro-shaping surfaces for elastocaloric applications. This paper presents fundamental analyses of the influence of EDM generator programs on the resulting removal depth, removal width and surface roughness of Ni-Ti sheets. Based on the perspective application in elastocaloric applications, adequate EDM programs are selected with regard to the targeted precision, surface roughness and minimal surface roughness.
Characteristics of cracks formed at the surface of NiTi during a single cycle of pseudoelastic deformation
Authors: Freiberg K E , Wonneberger R , Undisz A
Published: May 2021

Pseudoelastic deformation of NiTi usually results in cracks at the surface. Cracking is promoted by surface oxide layers that form, e.g., during heat treatments required for shape-setting of minimally invasive implants. In connection with the advancing miniaturization of minimally invasive implants, the question arises whether their mechanical integrity may get impaired by such cracks. In the present work, the characteristics of the cracks was investigated in cross section with the help of targeted preparation using focused ion-beams. SEM and TEM on samples after a single cycle of pseudoelastic deformation revealed that cracks extend perpendicular to the loading direction in the surface oxide layer and change to angles between 90° and 45° in the Ni-rich layer below. Pores observed in the surface oxide close to the Ni-rich layer did not prevent the extension of cracks towards the NiTi bulk. When the cracks reach the NiTi, blunting of the crack tip was observed. The crack length essentially corresponds to the thickness of the surface oxide layer and the Ni-rich layer. The findings provide data for estimating crack propagation in according implants in the future.
Parameter study on the electrical resistivity of plasma sprayed TiOx/Cr2O3 coatings
Authors: Bobzin K , Wietheger W , Heinemann H , Schacht A
Published: May 2021

Thermally sprayed coatings based on TiOx/Cr2O3 gain increased attention for the application as resistive heating elements. The higher resistivity of ceramic compared to metallic coatings improves the geometric flexibility of the coating as no long or complex conductor paths are required to achieve sufficient resistances. The main objective of this work is to understand the influence of the process parameters on plasma sprayed TiOx/Cr2O3 coatings. Therefore, a design of experiment method is conducted to investigate the effects on the coatings’ resistivity. Initially, the feedstock of TiOx with a weight proportion of 20 % Cr2O3 is characterized. A three cathode-plasma spray gun with an Ar/H2 plasma gas mixture is used to apply the coatings. The current, the amount of H2 in the plasma gas mixture as well as the stand-off distance of the spray gun are varied according to a circumscribed central composite (CCC) design. These three factors are found to be significant in terms of influencing the coatings’ resistivity and a corresponding regression model is established. Furthermore, a significant phase change of the powder due to the spraying process is detected by means of XRD.
Impact resistance of WC-Co reinforced HVAF-sprayed FeCrB-coatings
Authors: Bobzin K , Wietheger W , Heinemann H , Sommer J , Schulz M
Published: May 2021

This study describes the development of cost-effective FeCrB-coatings and the evaluation of these novel coatings against impact loads. The cost reduction is achieved by using a new and economical iron-based feedstock material with a small particel size distribution, which can be processed at high feeding rates with the HVAF process. The reduced particle size distribution enhances the application of near-net-shape coatings, minimizing the need for expensive, time-consuming grinding postprocesses. Thicker coatings usually result in higher thermal insulation, whereas thin near-net-shape coatings can reduce the thermal insulation. Dense FeCrB and FeCrB/WC-Co coatings were applied by HVAF with feeding rates of ṁ = 200 g/min and a particle size distribution of -20 + 3 μm. Through curvature measurements during the application it is shown that by integrating WC-Co into FeCrB the tensile residual stress state of the coating was minimized, which in turn increased the fracture toughness of the coating. The evaluation of the impact resistance was investigated by an impact test. The results show that the crater volume was halved by adding WC-Co in the FeCrB-coating. However, it is shown that the plastic deformability of the coating is minimized and a stronger cracking behavior can be observed.
High temperature treatment effects on the microstructure and properties of a plasma sprayed 25 mol% AI2O3-25 mol% Cr2O3-50 mol% TiO2 coating
Authors: Grimm M , Conze S , Berger L-M , Drehmann R , Lampke T
Published: May 2021

In this study, the influence of heat treatments up to 1200°C in vacuum on coatings prepared by atmospheric plasma spraying (APS) from a blend of 25 mol% Al2O3, 25 mol% Cr2O3 and 50 mol% TiO2 on microstructure, porosity, hardness and sliding wear resistance was investigated. The well-known transformation from α-Al2O3 to γ-Al2O3 occurred as a result of the spray process, as well as small amounts of titanium were found in Cr2O3 splats due to an interaction between the feedstock particles. No significant changes were found after a heat treatment at 400°C or 800°C. Heat treatment at 1200 °C led to complete coating delamination. Besides the retransformation of γ-Al2O3 to α-Al2O3, interactions between Cr2O3 and TiO2 splats and the formation of CrTi2O5 was observed. The formation of Al2Ti7O15 was observed in result of a reaction at the outer regions of the Al2O3 splats. At the same time, a reduction in porosity and healing of microcracks were observed as a result of sintering processes, which leads to an increase of the coating hardness to 1170 HV0.2.
Influence of the wire diameter and particle fraction of Fe-Al2O3/ZrO2 flux-cored wires processed by wire arc spraying on the abrasive wear properties of the coating
Authors: Gustke K , Drehmann R , Lampke T
Published: May 2021

The embedding of ceramic particles of a certain size and concentration in a ductile matrix is a strategy for producing wear-resistant coatings. In wire arc spraying, flux-cored wires with a metallic sheath and particle-filled core can be used for this purpose. The influence on wear properties of wire diameter and particle fraction has hardly been investigated so far. Due to the high kinetics of arc and gas flow, there are considerable challenges with regard to reproducibility, homogeneity and material efficiency. As a basis for a significantly improved understanding of the process, the relationships between the wire diameter, the particle fraction used and the wear resistance of the produced coatings have been investigated. The objects of investigation were flux-cored wires with an iron sheath and a particle filling of Al2O3/ZrO2. By using the ball-on-disc test and rubber wheel test, the wear resistance of the respective coatings was investigated.
Influence of diameter of the cored wires on abrasive wear resistance of arc sprayed coatings
Authors: Pokhmurska H , Student M , Paczkowski G , Holovchuk M , Chumalo H , Hvozdetskyi V , Schuberth S
Published: May 2021

To obtain wear-resistant coatings, the cored wires (CW) with a diameter of 1.6…1.8 mm as electrode materials are mainly used. Using the large-diameter CW enable significantly increase the filling of their shells with powder charges and, as a consequence, to essentially raise the content of alloying elements in the coating structure. The model cored wires of two basic alloying systems Fe – Cr – C and Fe – Cr – B with a diameter of 1.6 and 2.4 mm used for spraying. Three types of the cored wires (namely 50CrNi2B5MnSi, 250Cr21WVMnSi, 50Cr6Mn2MoSi) used in this study. It is found that more oxide phase (40…100 %) was in coatings formed with CW with a diameter of 2.4 mm compared with coatings formed with CW with a diameter of 1.6 mm with lower filling. It is established that the abrasive and gas-abrasive wear resistance of coatings with 250Cr21WVMnSi CW decreased, and with 50CrNi2B5MnSi CW increased due to the increase in the thickness of the lamellae in their structure with the use of CW of larger diameter. It was found that the higher the coefficient of microheterogeneity and chromium content in the lamellae, the higher the corrosion resistance of coatings.
Dissipation and energy gap
Authors: Trachenko K
Published: May 2021

The effect of anharmonicity (coupling) in the field theory generally results in dissipation of plane waves. It has been appreciated that anharmonicity and ensuing dissipation of plane waves can be accompanied by the emergence of the gapped momentum state. Here, we show that the same effect can lead to a gapped energy state and a dispersion relation where the frequency (energy) gap emerges explicitly. We discuss several notable properties of gapped energy and momentum states and connections between them.
A review on plant-mediated synthesis of silver nanoparticles, their characterization and applications
Authors: Chandraker Sandip Kumar , Ghosh Mithun Kumar , Lal Mishri , Shukla Ravindra
Published: May 2021

For decades, silver has been used as a non-toxic inorganic antimicrobial agent. Silver has a lot of potential in a variety of biological/chemical applications, particularly in the form of nanoparticles (NPs). Eco-friendly synthesis approach for NPs are becoming more common in nanobiotechnology, and the demand for biological synthesis methods is growing, with the goal of eliminating hazardous and polluting agents. Cultures of bacteria, fungi, and algae, plant extracts, and other biomaterials are commonly used for NP synthesis in the ‘green synthesis’ process. Plant-based green synthesis is a simple, fast, dependable, cost-effective, environmentally sustainable, and one-step method that has a significant advantage over microbial synthesis due to the lengthy process of microbial isolation and pure culture maintenance. In this report, we focussed on phytosynthesis of silver nanoparticles (AgNPs) and their characterization using various techniques such as spectroscopy (UV–vis, FTIR), microscopy (TEM, SEM), X-Ray diffraction (XRD), and other particle analysis. The potential applications of AgNPs in a variety of biological and chemical fields are discussed.
The Oxford Encyclopedia of the History of American Foreign Relations
Authors: Lawrence Mark
Published: May 2021

More than 111 scholarly articles

The study of US foreign relations is one of the most dynamic fields of American history. The availability of new sources in recent years has opened new opportunities for examining US behavior through the lenses of other nations. Meanwhile, historians of international affairs have increasingly borrowed the methods, questions, and insights of cultural and social history, enlivening their field and opening bold new lines of interpretation. Some scholars have moved away from the traditional focus on presidents, diplomats, intelligence chiefs, and military officers to examine the roles of activists, experts, journalists, athletes, and others in American foreign relations. This collection captures all these trends in a fully up-to-date, authoritative survey of US foreign relations across almost 250 years. More than 100 entries on topics ranging from the American Revolution to the wars in Afghanistan and Iraq provide basic background well-suited to readers approaching their topics for the first time. But the entries, written by a remarkable array of expert authors, also offer a valuable tool for experienced researchers and advanced scholars. Authors provide surveys of the scholarly literature related to each topic, along with guides to primary sources, including a rapidly growing number of online collections. The collection covers traditional topics like Anglo-American relations or the role of nuclear weapons in US diplomacy, while also considering newer themes like gender, LGBTQ issues, and environmental diplomacy.
Invited Commentary: Ionizing Radiation and Future Reproductive Health—Old Cohorts Still Deserve Attention
Authors: Lie Rolv T
Published: May 2021

Radiation from nuclear weapons or power plants has caused great concern among the public—concern that needs to be addressed with the best available data. Among the concerns associated with ionizing radiation are possible serious and far-reaching effects on reproductive health. Relevant data that can be used to address these concerns are scarce. The Hiroshima and Nagasaki bombings of World War II and the 1986 Chernobyl disaster in Ukraine are probably among the most dramatic and important sources of information on health effects, but much of the information is historical, and the exposed cohorts are getting old. In their accompanying article, Yamada et al. (Am J Epidemiol. 2021;190(11):2323–2333) revisit data on reproductive health outcomes in survivors of the Hiroshima and Nagasaki bombings during the years after the blasts. Exposure levels were very high, but after Yamada et al.’s reanalysis, effect estimates were low, and the evidence for overall effects on birth defects and perinatal mortality is still weak. The authors acknowledge that their data have limitations and that the generalizability of the findings is limited by the devastating conditions that prevailed in the 2 Japanese cities after the blasts.
Serum potassium changes due to concomitant ACEI/ARB and spironolactone therapy: A systematic review and meta-analysis
Authors: Villa-Zapata Lorenzo , Carhart Briggs S , Horn John R , Hansten Philip D , Subbian Vignesh , Gephart Sheila , Tan Malinda , Romero Andrew , Malone Daniel C
Published: May 2021

Purpose

To provide evidence of serum potassium changes in individuals taking angiotensin-converting enzyme inhibitors (ACEIs) and/or angiotensin receptor blockers (ARBs) concomitantly with spironolactone compared to ACEI/ARB therapy alone.

Methods

PubMed, Embase, Scopus, and Web of Science were searched for studies including exposure to both spironolactone and ACEI/ARB therapy compared to ACEI/ARB therapy alone. The primary outcome was serum potassium change over time. Main effects were calculated to estimate average treatment effect using random effects models. Heterogeneity was assessed using Cochran’s Q and I2. Risk of bias was assessed using the revised Cochrane risk of bias tool.

Results

From the total of 1,225 articles identified, 20 randomized controlled studies were included in the meta-analysis. The spironolactone plus ACEI/ARB group included 570 patients, while the ACEI/ARB group included 547 patients. Treatment with spironolactone and ACEI/ARB combination therapy compared to ACEI/ARB therapy alone increased the mean serum potassium concentration by 0.19 mEq/L (95% CI, 0.12-0.26 mEq/L), with intermediate heterogeneity across studies (Q statistic = 46.5, P = 0.004; I2 = 59). Sensitivity analyses showed that the direction and magnitude of this outcome did not change with the exclusion of individual studies, indicating a high level of reliability. Reporting risk of bias was low for 16 studies (80%), unclear for 3 studies (15%) and high for 1 study (5%).

Conclusion

Treatment with spironolactone in combination with ACEI/ARB therapy increases the mean serum potassium concentration by less than 0.20 mEq/L compared to ACEI/ARB therapy alone. However, serum potassium and renal function must be monitored in patients starting combination therapy to avoid changes in serum potassium that could lead to hyperkalemia.
Tectorigenin attenuates cognitive impairments in mice with chronic cerebral ischemia by inhibiting the TLR4/NF-κB signaling pathway
Authors: Feng Wei
Published: May 2021

This study aims to explore the effect of Tectorigenin in chronic cerebral ischemia (CCI)-induced cognitive impairment mice model. Cognitive impairment, hippocampal tissue histopathology, and myelin density in CCI mice were detected. HT22 cells were used to induce oxygen–glucose deprivation/reperfusion (OGD/R) injury. Cell viability and apoptosis of transfected HT22 cells and toll-like receptor-4 (TLR4)/nuclear factor-kappaB (NF-κB) pathway–related factor levels in hippocampal tissue and OGD/R models were detected. CCI caused cognitive impairment, hippocampal damage, and decreased myelin density in mice while promoting interleukin-1β, tumor necrosis factor-alpha, TLR4, myeloid differentiation primary response gene 88, p-p65, NLRP3, and ASC levels. Tectorigenin reversed the effects of CCI in mice and reversed the promoting effects of OGD/R on apoptosis and TLR4/NF-κB pathway–related factors levels, while overexpressed TLR4 reversed the effects of Tectorigenin in OGD/R-induced HT-22 cells. Tectorigenin alleviated cognitive impairment in CCI mice by inhibiting the TLR4/NF-κB signaling pathway.
Bistability in cell signalling and its significance in identifying potential drug-targets
Authors: Halder Suvankar , Ghosh Sumana , Chattopadhyay Joydev , Chatterjee Samrat
Published: May 2021

Motivation

Bistability is one of the salient dynamical features in various all-or-none kinds of decision-making processes. The presence of bistability in a cell signalling network plays a key role in input–output (I/O) relation. Our study is aiming to capture and emphasize the role of motif structure influencing the I/O relation between two nodes in the context of bistability. Here, a model-based analysis is made to investigate the critical conditions responsible for the emergence of different bistable protein–protein interaction (PPI) motifs and their possible applications to find the potential drug-targets.

Results

The global sensitivity analysis is used to identify sensitive parameters and their role in maintaining the bistability. Additionally, the bistable switching through hysteresis is explored to develop an understanding of the underlying mechanisms involved in the cell signalling processes, when significant motifs exhibiting bistability have emerged. Further, we elaborate the application of the results by the implication of the emerged PPI motifs to identify potential drug-targets in three cancer networks, which is validated with existing databases. The influence of stochastic perturbations that could hinder desired functionality of any signalling networks is also described here.

Supplementary information

Supplementary data are available at Bioinformatics online.
Ring-like late gadolinium enhancement for predicting ventricular tachyarrhythmias in non-ischaemic dilated cardiomyopathy
Authors: Chen Wensu , Qian Wen , Zhang Xinwei , Li Dongcheng , Qian Zhiyong , Xu Hai , Liao Shengen , Chen Xing , Wang Yao , Hou Xiaofeng , Patel Amit R , Xu Yi , Zou Jiangang
Published: May 2021

Aims

Myocardial fibrosis is associated with clinical ventricular tachyarrhythmia (VTA) events in patients with non-ischaemic dilated cardiomyopathy (DCM). Subepicardial or mid-wall ring-like late gadolinium enhancement (LGE) has received increasing attention in recent years. The aim of this study was to investigate the relationship between ring-like LGE and VTAs in DCM.

Methods and results

Patients diagnosed with non-ischaemic DCM who underwent cardiac magnetic resonance with LGE imaging at baseline were investigated. The composite outcome was the occurrence of VTAs defined as sustained ventricular tachycardia, ventricular fibrillation/flutter, aborted sudden cardiac death (SCD), SCD, and appropriate implantable cardioverter-defibrillator intervention. The final cohort comprised 157 patients, including 36 (22.9%) in no LGE group, 48 (30.6%) in focal LGE group, 40 (25.5%) in multi-focal LGE group, and 33 (21%) in ring-like LGE group. Ring-like LGE group patients were younger compared to focal and multi-focal LGE group (P < 0.001) with higher left ventricular ejection fraction (33.0% vs. 24.4% vs. 22.1%, P < 0.001). After a median of 13 ± 7 months follow-up, compared to patients with no LGE, the hazard ratios (HRs) with 95% confidence intervals (CIs) for VTAs were 2.90 (0.56–15.06), 5.55 (1.21–25.44), and 11.75 (2.66–51.92) for patients with focal LGE, multi-focal LGE, and ring-like LGE, respectively. After multivariable adjustment, ring-like LGE group remained associated with increased risk of VTAs (adjusted HR 10.00, 95% CI 1.54–64.98; P = 0.016) independent of the global LGE burden

Conclusion

The ring-like pattern of LGE is independently associated with an increased risk of VTAs in patients with non-ischaemic DCM.
The Atlantic salmon’s stress- and immune-related transcriptional responses to moderate hypoxia, an incremental temperature increase, and these challenges combined
Authors: Beemelmanns Anne , Zanuzzo Fábio S , Sandrelli Rebeccah M , Rise Matthew L , Gamperl A Kurt
Published: May 2021

The marine environment is predicted to become warmer, and more hypoxic, and these conditions may negatively impact the health and survival of coastal fish species, including wild and farmed Atlantic salmon (Salmo salar). Thus, we examined how: (1) moderate hypoxia (∼70% air saturation) at 12°C for 3 weeks; (2) an incremental temperature increase from 12°C to 20°C (at 1°C week−1) followed by 4 weeks at 20°C; and (3) treatment “2” combined with moderate hypoxia affected transcript expression in the liver of post-smolts as compared to control conditions (normoxia, 12°C). Specifically, we assessed the expression of 45 genes related to the heat shock response, oxidative stress, apoptosis, metabolism and immunity using a high-throughput qPCR approach (Fluidigm Biomark™ HD). The expression profiles of 27 “stress”-related genes indicated that: (i) moderate hypoxia affected the expression of several stress genes at 12°C; (ii) their expression was impacted by 16°C under normoxic conditions, and this effect increased until 20°C; (iii) the effects of moderate hypoxia were not additive to those at temperatures above 16°C; and (iv) long-term (4 weeks) exposure to 20°C, with or without hypoxia, resulted in a limited acclimatory response. In contrast, the expression of 15 immune-related genes was not greatly affected until temperatures reached 20°C, and this effect was particularly evident in fish exposed to the added challenge of hypoxia. These results provide valuable information on how these two important environmental factors affect the “stress” physiology and immunology of Atlantic salmon, and we identify genes that may be useful as hypoxia and/or temperature biomarkers in salmonids and other fishes.
NGSremix: a software tool for estimating pairwise relatedness between admixed individuals from next-generation sequencing data
Authors: Nøhr Anne Krogh , Hanghøj Kristian , Garcia-Erill Genís , Li Zilong , Moltke Ida , Albrechtsen Anders
Published: May 2021

Estimation of relatedness between pairs of individuals is important in many genetic research areas. When estimating relatedness, it is important to account for admixture if this is present. However, the methods that can account for admixture are all based on genotype data as input, which is a problem for low-depth next-generation sequencing (NGS) data from which genotypes are called with high uncertainty. Here, we present a software tool, NGSremix, for maximum likelihood estimation of relatedness between pairs of admixed individuals from low-depth NGS data, which takes the uncertainty of the genotypes into account via genotype likelihoods. Using both simulated and real NGS data for admixed individuals with an average depth of 4x or below we show that our method works well and clearly outperforms all the commonly used state-of-the-art relatedness estimation methods PLINK, KING, relateAdmix, and ngsRelate that all perform quite poorly. Hence, NGSremix is a useful new tool for estimating relatedness in admixed populations from low-depth NGS data. NGSremix is implemented in C/C++ in a multi-threaded software and is freely available on Github https://github.com/KHanghoj/NGSremix.