Search

In this paper, the concept, microstructure and properties of the Ni-Cr-Ta-Al-C complex phase alloy are presented. The alloy was designed to work at elevated temperatures, in a chemically aggressive environment and under harsh wear conditions. The alloy was examined in an as-cast state and after heat treatment using a number of complementary techniques such as: scanning electron microscopy, 3D reconstruction by means of focused ion beam-scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nanoindentation, dilatometry, hardness measurements and in-situ tensile tests at elevated temperatures. The microstructure of the alloy is comprised of a dendritic chromium-rich nickel-based matrix, which is strengthened by spheroidal precipitations of the γ’ Ni 3 (AlTa) phase as well as Chinese script-like TaC and Cr 7 C 3 carbides. Analysing hardness and microstructural changes of the alloy after solution treatment and after aging in different conditions allows to optimise the alloy's heat treatment procedure. It was found that the alloy achieved the highest hardness values after aging at 800 °C, which is related with the evolution of the γ’ phase. Additionally, it was discovered that primary carbides are stable up to at least 1150 °C, which is promising from the viewpoint of working at elevated temperatures and under harsh wear conditions. The herein reported results show that the combination of eutectic carbides and ordered γ’ phase for strengthening and, possibly, improving wear resistance of the alloy is effective up to at least 850 °C. [ABSTRACT FROM AUTHOR]

Sedentary behavior is defined as sitting or lying with low energy expenditure. Humans in industrialized societies spend an increasing amount of time in sedentary behaviors every day. This has been associated with detrimental health outcomes. Despite a growing interest in the health effects of sedentary behavior at work, associations remain unclear, plausibly due to poor and diverse methods for assessing sedentary behavior. Thus, good practice guidance for researchers and practitioners on how to assess occupational sedentary behavior are needed. The aim of this paper is to provide a practical guidance for practitioners and researchers on how to assess occupational sedentary behavior. Ambulatory systems for use in field applications (wearables) are a promising approach for sedentary behavior assessment. Many different small-size consumer wearables, with long battery life and high data storage capacity are commercially available today. However, no stand-alone commercial system is able to assess sedentary behavior in accordance with its definition. The present paper offers decision support for practitioners and researchers in selecting wearables and data collection strategies for their purpose of study on sedentary behavior. Valid and reliable assessment of occupational sedentary behavior is currently not easy. Several aspects need to be considered in the decision process on how to assess sedentary behavior. There is a need for development of a cheap and easily useable wearable for assessment of occupational sedentary behavior by researchers and practitioners. [ABSTRACT FROM AUTHOR]

The steel–TiB 2 composites were fabricated by Spark Plasma Sintering (SPS) process. The effect of the sintering temperature (1000 °C and 1100 °C) and time (5 and 30 min) on the microstructure, densification, and physical as well as mechanical properties of the composites was investigated. The experimental data showed that maximum relative density of 97–99% was achieved for composites sintered at 1100 °C. The characterization of the composites was performed by X-ray Diffraction and Scanning Electron Microscopy. The mechanical properties such as microhardness and compression strength were investigated. The microstructural study revealed that the TiB 2 particles were distributed uniformly in the steel matrix. The results show that Young’s modulus, microhardness and compression strength of composites increased with the increase of sintering temperature. The highest physical and mechanical properties were obtained for the composites sintered at 1100 °C for 30 min. [ABSTRACT FROM AUTHOR]

• Composite layers were fabricated in steel casting using by reactive coatings. • In order to limit reactive infiltration the addition of moderator was added. • Moderator is a mixture of metal and non-metal powders. • Moderator decreases the heat effect within the area of the TiC reaction. This paper concerns a method of fabricating a composite layer in cast steel castings. During the research, the fragmentation phenomenon of the composite layer was identified, which was revealed by the nonuniform structure in the whole length. In order to limit the fragmentation phenomenon understood as tending to the creation of the structural heterogeneity, discontinuity, and agglomeration of the reinforcement, the addition of a moderator was added. The presented results of our structural investigations indicate the stabilization of the composite layer with a 50 wt% addition of the moderator. The conducted research of XRD analysis and SEM indicated the presence of TiC within the composite zone area. The average hardness ranged between 650 and 810 HV1, which was an increase of more than a three-fold increase when compared to the matrix. [ABSTRACT FROM AUTHOR]

The locally varying tetragonality in martensite grains of a high‑carbon steel (1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD) with a spatial resolution in the order of 100 nm. Compared to spatially integrating X-ray diffraction, which yielded an average tetragonality of c / a = 1.05, the EBSD measurements in the scanning electron microscope allowed to image a local variation of the lattice parameter ratio c / a in the range of 1.02 ≤ c / a ≤ 1.07. The local variation of tetragonality is confirmed by two different EBSD data analysis approaches based on the fitting of simulated to experimental EBSD patterns. The resulting EBSD-based tetragonality maps are pointing to a complex interaction of carbon concentration and local lattice distortions during the formation process of martensitic structures. • Fe-1.2%C martensite tetragonality (c/a ratio) was resolved using EBSD pattern matching. • EBSD pattern matching results are compared to XRD. • EBSD pattern matching provides spatial information about c/a. • c/a of Fe-1.2%C martensite varies significantly in the measured sample area, with an average value close to one acquired with XRD. [ABSTRACT FROM AUTHOR]

• Quasicrystal EBSD mapping using commercial software. • Approximants structures used for EBSD mapping of quasicrystals. • Pseudosymmetry data treatment routines. • MTEX based quasicrystal EBSD data visualization. Orientation mapping of quasicrystalline materials is demonstrated using crystalline approximant structures in the technique of electron backscatter diffraction (EBSD). The approximant-based orientations are symmetrised according to the rotational point group of the quasicrystal, including the visualization of orientation maps using proper colour keys for quasicrystal symmetries. Alternatively, approximant-based orientation data can also be treated using pseudosymmetry post-processing options in the EBSD system software, which enables basic grain size estimations. Approximant-based orientation analyses are demonstrated for icosahedral and decagonal quasicrystals. [ABSTRACT FROM AUTHOR]

An aluminium alloy (5005) was hard anodised using pulsed current. The influence of current density and bath temperature on the electrical parameters of the anodising process was studied. It was found that elevated bath temperature does not deteriorate the mechanical properties of the coatings, such as wear and scratch resistance. The following anodising parameters: current density equal to 4 A·dm−2 and bath temperature 4 °C gives the lowest value of electric energy necessary to produce the coating. Thus, they are beneficial for maintaining cost effectiveness of the anodising plant. • Elevated bath temperature does not deteriorate coatings' wear resistance. • Coatings' scratch resistance does not depend on anodising conditions. • Low current density and high bath temperature offer low anodising cost. • Anodising does not increase the coating roughness when compared to the substrate. [ABSTRACT FROM AUTHOR]

Cast Fe-21.2 Mn-2.99 Si-2.73 Al-0.02 wt.% C alloy ingot was homogenized at 1150 °C, hot-rolled at starting temperature 1000 °C, solution treated at 1150 °C for 1 h and cold-rolled to 56% thickness reduction. Metallographic and X-ray diffraction studies revealed that, for small degrees of deformation, ε martensite had nucleated within numerous stacking faults. EBSD analysis showed that α ′ martensite also formed within the ε plates. Plastic deformation occurred by mechanical twinning and martensitic transformations, both γ → ε and γ → ε → α ′ (TWIP and TRIP effect), with the Burgers (Shoji–Nishiyama) {0 0 0 1} ε ||{1 1 1} γ , 〈1 1 2 0〉 ε || 〈1 1 0〉 γ and Kurdjumov–Sachs {1 1 1} γ ||{1 1 0} α , 〈1 1 0〉 γ ||〈1 1 1〉 α relations between the austenite ( γ ), and martensite ( ε and α ′). [ABSTRACT FROM AUTHOR]

The present study explores the synthesis and bio-safety evaluation of gadolinium-doped carbon quantum dots (GCQDs) as a potential dual-contrast agent for diagnostic imaging. GCQDs exhibit both fluorescent and magnetic properties, making them suitable for UV-Vis and magnetic resonance imaging (MRI). The synthesis of GCQDs was achieved via hydrothermal treatment, incorporating gadolinium into the carbon quantum dot matrix. The magnetic properties of GCQDs were analyzed, showing significantly enhanced values compared to gadobutrol, a common MRI contrast agent. However, synthesis constraints limit the gadolinium content achievable in nanodots. To assess the safety of GCQDs, their effects on the embryonic development of zebrafish ( Danio rerio ) were examined. Various concentrations of GCQDs were tested, observing mortality rates, hatchability, malformations, heartbeats, spontaneous movement, and GCQDs uptake. Dialysis studies indicated that gadolinium ions are incorporated into the internal structure of the carbon nanodots. Zebrafish toxicity tests revealed that while survival rates were comparable to control groups, hatchability decreased significantly with higher gadolinium concentrations in GCQDs. Fluorescence microscopy showed no statistical differences in the fluorescence intensity between groups. These findings suggest that GCQDs could serve as an effective dual-contrast agent, combining the optical imaging capabilities of CQDs with the enhanced MRI contrast provided by gadolinium. This study underscores the need for further research on the synthesis methods and biological interactions of GCQDs to ensure their safety and efficacy in medical applications.

Background: The measurement of handgrip force responses is important in many aspects, for example: to complement neurological assessments, to investigate the contribution of muscle mass in predicting functional outcomes, in setting realistic treatment goals, evaluating rehabilitation strategies. Normative data about handgrip force can assist the therapist in interpreting a patient's results compared with healthy individuals of the same age and gender and can serve as key decision criteria. In this context, establishing normative values of handgrip strength is crucial. Hence, the aim of the this study is to develop a tool that could be used both in rehabilitation and in the prevention of work-related musculoskeletal disorders. This tool takes the form of population-specific predictive equations, which express maximum handgrip force as a function of age., Methodology: In order to collect data from studies measuring maximum handgrip force, three databases were searched. The search yielded 5,058 articles. Upon the removal of duplicates, the screening of abstracts and the full-text review of potentially relevant articles, 143 publications which focussed on experimental studies on various age groups were considered as fulfilling the eligibility criteria. A comprehensive literature review produced 1,276 mean values of maximum handgrip force., Results: A meta-analysis resulted in gender- and world region-specific (general population, USA, Europe and Asia) equations expressing maximum force as a function of age. The equations showed quantitative differences and trends in maximum handgrip force among age, gender and national groups. They also showed that values of maximum handgrip force are about 40% higher for males than for females and that age-induced decrease in force differs between males and females, with a proved 35% difference between the ages of 35 and 75. The difference was lowest for the 60-64 year olds and highest for the 18-25 year-olds. The equations also showed that differences due to region are smaller than those due to age or gender., Conclusions: The equations that were developed for this study can be beneficial in setting population-specific thresholds for rehabilitation programmes and workstation exposure. They can also contribute to the modification of commonly used methods for assessing musculoskeletal load and work-related risk of developing musculoskeletal disorders by scaling their limit values., Competing Interests: The authors declare there are no competing interests., (©2024 Roman-Liu et al.)

Background: Musculoskeletal disorders (MSDs), especially in the lumbar spine, are a leading concern in occupational health. Work activities associated with excessive exposure are a source of risk for MSDs. The optimal design of workplaces requires changes in both sitting and standing postures. In order to secure such a design scientifically proved quantitative data are needed that would allow for the assessment of differences in spine load due to body posture and/or exerted force. Intradiscal pressure (IP) measurement in the lumbar spine is the most direct method of estimating spinal loads. Hence, this study aims at the quantitative evaluation of differences in lumbar spine load due to body posture and exerted forces, based on IP reported in publications obtained from a comprehensive review of the available literature., Methodology: In order to collect data from studies measuring IP in the lumbar spine, three databases were searched. Studies with IP for living adults, measured in various sitting and standing postures, where one of these was standing upright, were included in the analysis. For data to be comparable between studies, the IP for each position was referenced to upright standing. Where different studies presented IP for the same postures, those relative IPs (rIP) were merged. Then, an analysis of the respective outcomes was conducted to find the possible relationship of IPs dependent on a specific posture., Results: A preliminary analysis of the reviewed papers returned nine items fulfilling the inclusion and exclusion criteria. After merging relative IPs from different studies, rIP for 27 sitting and 26 standing postures was yielded. Some of the data were useful for deriving mathematical equations expressing rIP as a function of back flexion angle and exerted force in the form of a second degree polynomial equation for the standing and sitting positions. The equations showed that for the standing posture, the increase in IP with increasing back flexion angle is steeper when applying an external force than when maintaining body position only. In a sitting position with the back flexed at 20°, adding 10 kg to each hand increases the IP by about 50%. According to the equations developed, for back flexion angles less than 20°, the IP is greater in sitting than in standing. When the angle is greater than 20°, the IP in the sitting position is less than in the standing position at the same angle of back flexion., Conclusions: Analysis of the data from the reviewed papers showed that: sitting without support increases IP by about 30% in relation to upright standing; a polynomial of the second degree defines changes in IP as a function of back flexion for for both postures. There are differences in the pattern of changes in IP with a back flexion angle between sitting and standing postures, as back flexion in standing increases IP more than in sitting., Competing Interests: The authors declare there are no competing interests., (©2023 Roman-Liu et al.)

A band width determination using the first derivative of the band profile systematically underestimates the true Bragg angle. Corrections are proposed to compensate for the resulting offset Δ a / a of the mean lattice parameters derived from as many Kikuchi band widths as possible. For dynamically simulated Kikuchi patterns, Δ a / a can reach up to 8% for phases with a high mean atomic number Z , whereas for much more common low- Z materials the offset decreases linearly. A predicted offset Δ a / a = f ( Z ) is therefore proposed, which also includes the unit-cell volume and thus takes into account the packing density of the scatterers in the material. Since Z is not always available for unknown phases, its substitution by Z max , i.e. the atomic number of the heaviest element in the compound, is still acceptable for an approximate correction. For simulated Kikuchi patterns the offset-corrected lattice parameter deviation is Δ a / a < 1.5%. The lattice parameter ratios, and the angles α, β and γ between the basis vectors, are not affected at all., (© Gert Nolze et al. 2023.)

The derivation of a crystal structure and its phase-specific parameters from a single wide-angle backscattered Kikuchi diffraction pattern requires reliable extraction of the Bragg angles. By means of the first derivative of the lattice profile, an attempt is made to determine fully automatically and reproducibly the band widths in simulated Kikuchi patterns. Even under such ideal conditions (projection centre, wavelength and lattice plane traces are perfectly known), this leads to a lattice parameter distribution whose mean shows a linear offset that correlates with the mean atomic number Z of the pattern-forming phase. The consideration of as many Kikuchi bands as possible reduces the errors that typically occur if only a single band is analysed. On the other hand, the width of the resulting distribution is such that higher image resolution of diffraction patterns, employing longer wavelengths to produce wider bands or the use of higher interference orders is less advantageous than commonly assumed., (© Gert Nolze et al. 2023.)

A pseudosymmetric description of the crystal lattice derived from a single wide-angle Kikuchi pattern can have several causes. The small size (<15%) of the sector covered by an electron backscatter diffraction pattern, the limited precision of the projection centre position and the Kikuchi band definition are crucial. Inherent pseudosymmetries of the crystal lattice and/or structure also pose a challenge in the analysis of Kikuchi patterns. To eliminate experimental errors as much as possible, simulated Kikuchi patterns of 350 phases have been analysed using the software CALM [Nolze et al. (2021). J. Appl. Cryst. 54 , 1012-1022] in order to estimate the frequency of and reasons for pseudosymmetric crystal lattice descriptions. Misinterpretations occur in particular when the atomic scattering factors of non-equivalent positions are too similar and reciprocal-lattice points are systematically missing. As an example, a pseudosymmetry prediction depending on the elements involved is discussed for binary AB compounds with B 1 and B 2 structure types. However, since this is impossible for more complicated phases, this approach cannot be directly applied to compounds of arbitrary composition and structure., (© Gert Nolze et al. 2023.)

Purpose . The purpose of this article was to determine how characteristics of bimanual coordination tasks affect the quality of performance and to determine the impact of these characteristics on muscular activation of the upper limbs, with consideration of age-related differences. Methods . The research was carried out on two groups consisting of 25 people aged 20-30 and 60-67 years. The subjects performed seven tasks that varied in coordination mode, tracking mode and outline-tracing. The main measures of task performance were calculated on the basis of the difference between the position of the target and tracing cursors. Cohen's d value was calculated to show differences in measures between groups. Results . There were higher values of error and variability measures for elderly people compared to young. Complex tasks showed the largest difficulty, which suggests that, when performed, such tasks have the greatest potential to improve coordination skills. Tasks during which both limbs contribute to the movement of one cursor proved the most appropriate. Conclusion . The tracking mode is of great importance for the quality of performance in motor coordination tasks, while the performance of tasks with imposed speed is much more strongly age-sensitive than performance with a freely chosen speed.

A new software is presented for the determination of crystal lattice parameters from the positions and widths of Kikuchi bands in a diffraction pattern. Starting with a single wide-angle Kikuchi pattern of arbitrary resolution and unknown phase, the traces of all visibly diffracting lattice planes are manually derived from four initial Kikuchi band traces via an intuitive graphical user interface. A single Kikuchi bandwidth is then used as reference to scale all reciprocal lattice point distances. Kikuchi band detection, via a filtered Funk transformation, and simultaneous display of the band intensity profile helps users to select band positions and widths. Bandwidths are calculated using the first derivative of the band profiles as excess-deficiency effects have minimal influence. From the reciprocal lattice, the metrics of possible Bravais lattice types are derived for all crystal systems. The measured lattice parameters achieve a precision of <1%, even for good quality Kikuchi diffraction patterns of 400 × 300 pixels. This band-edge detection approach has been validated on several hundred experimental diffraction patterns from phases of different symmetries and random orientations. It produces a systematic lattice parameter offset of up to ±4%, which appears to scale with the mean atomic number or the backscatter coefficient., (© Gert Nolze et al. 2021.)

The aim of this study was to identify effective work place intervention strategies for the prevention of low back pain (LBP). The study focused on interventions to two major groups: personal interventions and technical interventions. Data basis were searched for with inclusion criteria: study design based on randomised controlled trial; outcome measures including non-specific LBP occurrence expressed by prevalence or intensity; intervention met the definition of the technical and/or personal (physical exercises, behavioural training, educational) intervention programme. Eighteen papers were selected for full analysis. The diversification of quantitative indicators of differences between control and intervention groups were carried out using Cohen's d index. The results of analysis showed strong differences in effects among intervention strategies, as well as among different cases within similar intervention strategies. LBP severity before intervention and the length of intervention were discussed as potentially influencing factors. The results of the analysis suggest that the most effective strategies for LBP prevention include technical modifications of the workstand and education based on practical training. Behavioural and physical training seems to be of lesser importance. LBP severity before intervention and the time when the measurements of outcome measures take place play an important role in the effectiveness of intervention.

A historical tool for crystallographic analysis is provided by the Hilton net, which can be used for manually surveying the crystal lattice as it is manifested by the Kikuchi bands in a gnomonic projection. For a quantitative analysis using the Hilton net, the projection centre as the relative position of the signal source with respect to the detector plane needs to be known. Interplanar angles are accessible with a precision and accuracy which is estimated to be ≤0.3°. Angles between any directions, e.g. zone axes, are directly readable. Finally, for the rare case of an unknown projection-centre position, its determination is demonstrated by adapting an old approach developed for photogrammetric applications. It requires the indexing of four zone axes [ uvw ] i in a backscattered Kikuchi diffraction pattern of a known phase collected under comparable geometric conditions., (© Gert Nolze et al. 2020.)

Purpose: The aim of the research was a comparative analysis of the back lumbar load assessment using three methods: two with continuous input data and evaluation procedures based on mathematical relationships (ShiftBack, 3DSSPP) and one method with categorized input data and tabular load estimation procedures (REBA)., Methods: For the analysis, work activities and the value of applied force were selected. Among the analyzed 24 work activities were those during which there was a symmetrical load, as well as those during which the applied force or the assumed position of the body caused a lack of load symmetry., Results: The results show that the REBA method differentiates 24 cases of unit load into six levels, while the other two methods provide 24 different values between cases. Cases differing in load even over 100%, when assessed according to the 3DSSPP or ShiftBack do not differ in the assessment of REBA. Differences in the assessment of the same tasks between the results obtained from 3DSSPP and ShiftBack that were above 15% concern only 7 cases., Conclusions: A comparative analysis of the assessment of the lumbar part of the back using three methods indicates strong correlations between the results of the assessment carried out using 3DSSPP and ShiftBack. Smaller relationships were demonstrated by comparing these two methods with the REBA method.

The paper presents a new method of ergonomic evaluation of gloves protecting against cuts and stabs during knife use, consisting of five manual dexterity tests. Two of them were selected based on the available literature and relevant safety standards, and three were developed by the authors. All of the tests were designed to simulate occupational tasks associated with meat processing as performed by the gloved hand in actual workplaces. The tests involved the three most common types of protective gloves (knitted gloves made of a coverspun yarn, metal mesh gloves, and metal mesh gloves with an ergonomic polyurethane tightener) and were conducted on a group of 20 males. The loading on the muscles of the upper limb (adductor pollicis, flexor carpi ulnaris, flexor carpi radialis, and biceps brachii) was measured using surface electromyography. For the obtained muscle activity values, correlations were found between the glove type and loading of the upper limb. ANOVA showed that the activity of all muscles differed significantly between the five tests. A relationship between glove types and electromyographic results was confirmed at a significance level of α = 0.05., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

BixLa1-xVO4 solid solutions were obtained in the form of fine powder via a microwave-assisted hydrothermal route. The presence of a solid solution in the studied system was confirmed using X-ray diffraction (XRD) and optical spectroscopy techniques. Pure BiVO4 and LaVO4 were obtained in the monoclinic form, whereas solid solutions in the tetragonal, zircon-type structure. The optical band gap dependence on the composition of the solid solution is parabolic, thus there is a possibility to tune this parameter in a wide concentration range, from 2.4 to 4.0 eV. An absorption coefficient maximum is also concentration-dependent, possibly, due to the structural disorder of the samples. Solid solutions with Bi(3+) concentration between 11.94 and 32.57 at.% exhibit intense, green luminescence. This indicates the presence of Bi-originated electronic states within the band gap. The value of the conduction band edge potential, measured by both electrochemical impedance spectroscopy and work function measurements, is concentration-independent. Moreover, solid solutions exhibit a photoelectrochemical photocurrent switching effect, thus they may be promising materials for molecular electronics and as dioxygen activators.