bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Invited Commentary: Ionizing Radiation and Future Reproductive Health—Old Cohorts Still Deserve Attention
Authors: Lie Rolv T 
Published: May 2021

AbstractRadiation 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

Abstract

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

ABSTRACTThis 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.