Analysis of the Mixing of Filler and Base Materials in Arc-Welded Single-Bead Surface Welds Using an EDXS Method

This article deals with an analysis of mixing and determines the admixing rate of a base S355 steel plate in single-bead surface welds by measuring the chemical composition using a plane-scan energy dispersive X-ray spectroscopy (EDXS) on metallographic cross-sections. The results show that obtaining a larger number of EDXS measurements does not necessarily lead to obtaining a more accurate admixing rate. Due to the ever-present segregations that are generally near the base material, the disadvantage of this method is the subjective influence of the SEM operator on the estimated admixing rate. To obtain relevant results, a sufficiently wide area of well-mixed melt, including segregations, must be analyzed. This study showed that by using a sufficiently large number of appropriately selected sites with a sufficiently large surface area, it is possible to estimate the admixing rate from the chemical composition with an accuracy of ≥96% for the geometrically determined admixing rate D = 30%. From several equations, the best result showed an equation which is the arithmetic mean of the two different arithmetic means and in which the artificial influencing factor of the segregations of the base material is taken into account. With this equation, the same value of admixing rate, D = 30%, was obtained using the comparative geometric method.

Development of a Multidirectional Wire Arc Additive Manufacturing (WAAM) Process with Pure Object Manipulation: Process Introduction and First Prototypes

Wire Arc Additive Manufacturing (WAAM) with eccentric wire feed requires defined operating conditions due to the possibility of varying shapes of the deposited and solidified material depending on the welding torch orientation. In consequence, the produced component can contain significant errors because single bead geometrical errors are cumulatively added to the next layer during a building process. In order to minimise such inaccuracies caused by torch manipulation, this article illustrates the concept and testing of object-manipulated WAAM by incorporating robotic and welding technologies. As the first step towards this target, robotic hardware and software interfaces were developed to control the robot. Alongside, a fixture for holding the substrate plate was designed and fabricated. After establishing the robotic setup, in order to complete the whole WAAM process setup, a Gas Metal Arc Welding (GMAW) process was built and integrated into the system. Later, an experimental plan was prepared to perform single and multilayer welding experiments as well as for different trajectories. According to this plan, several welding experiments were performed to decide the parametric working range for the further WAAM experiments. In the end, the results of the first multilayer depositions over intricate trajectories are shown. Further performance and quality optimization strategies are also discussed at the end of this article.

Wire Laser Metal Deposition Additive Manufacturing of Duplex Stainless Steel Components—Development of a Systematic Methodology

A systematic four-stage methodology was developed and applied to the Laser Metal Deposition with Wire (LMDw) of a duplex stainless steel (DSS) cylinder > 20 kg. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder were produced. This stepwise approach allowed the development of LMDw process parameters and control systems while the volume of deposited material and the geometrical complexity of components increased. The as-deposited microstructure was inhomogeneous and repetitive, consisting of highly ferritic regions with nitrides and regions with high fractions of austenite. However, there were no cracks or lack of fusion defects; there were only some small pores, and strength and toughness were comparable to those of the corresponding steel grade. A heat treatment for 1 h at 1100 °C was performed to homogenize the microstructure, remove nitrides, and balance the ferrite and austenite fractions compensating for nitrogen loss occurring during LMDw. The heat treatment increased toughness and ductility and decreased strength, but these still matched steel properties. It was concluded that implementing a systematic methodology with a stepwise increase in the deposited volume and geometrical complexity is a cost-effective way of developing additive manufacturing procedures for the production of significantly sized metallic components.

Bead-Immobilized Multimodal Molecular Beacon-Equipped DNA Machinery for Specific RNA Target Detection: A Prototypical Molecular Nanobiosensor

A variety of nanostructured diagnostic tools have been developed for the precise detection of known genetic variants. Molecular beacon systems are very promising tools due to their specific selectivity coupled with relatively lower cost and time requirements than existing molecular detection tools such as next generation sequencing or real-time PCR (polymerase chain reaction). However, they are prone to errors induced by secondary structure responses to environmental fluctuations, such as temperature and pH. Herein, we report a temperature-insensitive, bead-immobilized, molecular beacon-equipped novel DNA nanostructure for detection of cancer miRNA variants with the consideration of thermodynamics. This system consists of three parts: a molecular beacon for cancer-specific RNA capture, a stem body as a core template, and a single bead for solid-support. This DNA system was selectively bound to nanosized beads using avidin–biotin chemistry. Synthetic DNA nanostructures, designed based on the principle of fluorescence-resonance enhanced transfer, were effectively applied for in vitro cancer-specific RNA detection. Several parameters were optimized for higher performance, with a focus on thermodynamic stability. Theoretical issues regarding the secondary structure of a single molecular beacon and its combinatory forms were also studied. This study provides design guidelines for new sensing systems of miRNA variation for next-generation biotechnological applications.

Реконструкция украшений могильника Киняминский II

The article is devoted to an issue that has not received sufficient coverage in the scientific literature — the artistic reconstruction of the Ugric jewelry in the middle ages. The methods and stages of experimental artistic reconstruction of women's ornaments of temporal rings and noisy suspensions of the Kinyaminsky II burial ground (Surgut region, Khanty-Mansi Autonomous Okrug — Ugra) are described. In accordance with the research objectives, the graphic reconstruction of jewelry made by V.I. Semenova was studied, and the analysis of Ugra Museum collections was carried out based on materials, technological methods of execution, size, and shape. 158 items of women's jewelry were studied: ordinary simple bracelet-like rings, single-bead; two-bead, three-bead, multi-bead, four- and five-lobed, zoomorphic with the image of stylized figures of the beast; as well as numerous elements and fragments of the temporal rings (XII-XVI centuries). The comparison revealed the differences in the graphic reconstruction of V.I. Semyonova from the studied items of museum collections in the structure of the arched base-shield. A graphic reconstruction of the temporal rings from the Kinyaminsky II burial ground was performed, followed by an experimental reconstruction in the material. The research results are significant in the context of the study of ethnocultural processes, as well as the development of techniques of arts and crafts, the formation of traditions of folk art. Статья посвящена вопросу, который не получил достаточного освещения в научной литературе, — художественной реконструкции накосных украшений угров в Средние века. Описаны методы, этапы экспериментальной художественной реконструкции женских украшений височных колец, шумящих подвесок могильника Киняминский II (Сургутский район, Ханты-Мансийский автономный округ — Югра). В ходе исследования была изучена графическая реконструкция украшений, выполненная В.И. Семеновой, проведен анализ музейных коллекций Югры по материалам, технологическим приемам исполнения, размерам, форме. Изучено 158 единиц женских украшений: обычные простые браслетообразные кольца, однобусинные; двухбусинное, трехбусинные, многобусинные, четырех- и пятилопастные, зооморфные с изображением стилизованных фигур зверя; а также многочисленные элементы и осколки височных колец (XII–XVI вв.). В ходе исследования выявлены отличия графической реконструкции В.И. Семеновой от исследованных украшений музейных коллекций в строении арочной основы-щитка. Выполнена графическая реконструкция височных колец из могильника Киняминский II, затем проведена экспериментальная реконструкция в материале. Результаты исследования значимы в контексте изучения этнокультурных процессов, а также развития техник декоративно-прикладного творчества, формирования традиций народного искусства.