Stefan Nagy

Stefan Nagy
Slovak Academy of Sciences | SAV · Institute of Materials and Machine Mechanics

PhD.

About

67
Publications
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699
Citations

Publications

Publications (67)
Article
Full-text available
This is an exclusively systematic background study reviewing 85 Mesozoic (latest Jurassic and Cretaceous) cockroaches and praying mantises from northern palaeo-polar (i.e. deposited within polar circles) deposits in Yakutia, Taimyr, Khabarovsk, Magadan and Chukotka (Russia), revealing 15 new species, which are herein characterised using systematic...
Article
In addition to its use as a lightweight material, pure magnesium is a promising candidate for prospective bioimplants considering its excellent biocompatible properties. Regardless of what Mg application is used, the ultimate goal is to improve magnesium's mechanical properties and degradation behaviour. Because of the high affinity for oxygen nati...
Article
Full-text available
While the reverse water-gas shift (RWGS) reaction holds great promise as a method of converting CO2 to CO and subsequently into valuable fuels, achieving its commercial viability requires the development of highly efficient, selective, durable, and low-cost catalysts. Recently, thin-film nanocatalysts produced through plasma deposition (PECVD) have...
Article
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The use of silver-based antimicrobial materials has been growing recently. Considering the threat of developing silver-resistant bacteria, it is essential to address the endurance of such materials and the amount of silver released into the environment. Here we report on a durable, antibacterial Ag/TiBx nanocomposite coating prepared by conventiona...
Article
Alloying of transition metal diborides with other metals seems to be a suitable way to maintain their excellent mechanical properties under high-temperature loads. Here, we focus on the perspective tantalum diboride (TaB 2 ) hard film, where we investigate the effect of aluminum alloying on the thermally induced structural evolution and mechanical...
Article
This work deals with the mechanical properties and microstructure of additively manufactured (AM) 316L stainless steels strengthened with Al2O3 nanoparticles. At first, the critical processing parameters of laser powder bed fusion (LPBF) were optimized using Taguchi analysis in terms of laser power (180–210 W), scan speed (90–270 mm/s), hatch space...
Article
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The present work investigates the influence of isothermal annealing on the microstructure and oxidation behavior of nanocomposite coatings. AlTiSiN/TiSiN coatings with TiSiN adhesive layer were deposited onto a high-speed steel substrate via physical vapor deposition. The coatings were investigated in the as-deposited state as well as after anneali...
Article
This work reports on various thermally induced planar defects formed in ternary V1-xMoxB2-Δ coatings with different influence on mechanical properties. V0.58Mo0.42B1.9 and V0.37Mo0.63B1.2 films were prepared by magnetron sputtering and annealed in vacuum up to 1300°C. Depending on the stoichiometry, different types of planar defects were identified...
Book
Full-text available
The impulse for writing the scientific monograph Historical Positive Organs within the Territory of Slovakia was largely our systematic (basic) research in the field of individual types of organs within our territory. We have gained new knowledge in our research over a longer period of time, as it is not always possible to look deeper into historic...
Article
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Development of new types of antimicrobial coatings is of utmost importance due to increasing problems with pathogen transmission from various infectious surfaces to human beings. In this study, new types of highly potent antimicrobial polyurethane composite films encapsulated by hydrophobic riboflavin-based carbon polymer dots are presented. Detail...
Article
FeCoCrNiMn high entropy alloy powders were employed to produce coatings on carbon steel through high pressure cold spray (at 1100 °C and 7 MPa in temperature and pressure respectively). X-ray diffraction of the sprayed material revealed a dense coating with the retention of the original crystallographic structure. Once splatted, particles revealed...
Preprint
Full-text available
Coverage-guided fuzzing's aggressive, high-volume testing has helped reveal tens of thousands of software security flaws. While executing billions of test cases mandates fast code coverage tracing, the nature of binary-only targets leads to reduced tracing performance. A recent advancement in binary fuzzing performance is Coverage-guided Tracing (C...
Article
Zirconium diboride (ZrB 2 ) represents a promising hard coating material for demanding high-temperature applications and could provide an excellent basis for fine-tuning mechanical properties via the concept of alloying. Here, combining density functional theory and experiments, we investigate the effect of aluminum alloying on thermally induced st...
Article
The common drawback of ceramic transition-metal boride films, the inherent brittleness, limits their practical applications under thermal load. Yttrium tetraboride (YB4), having a high melting temperature, chemical inertness, high hardness, and low Young's modulus of elasticity in the bulk form, is a promising candidate for thin films capable of wi...
Article
In this research, the effect of pre-heat treatment of mechtrod and post-processing heat treatment of coating on the microstructure and corrosion behavior of the nickel-aluminide reinforced Al-Cu-Mg alloy coating has been studied. Results show that under a similar heat treatment condition of mechtrod, no significant difference is observed in the coa...
Patent
Biopreparát z Exiguobacterium undae obsahuje dva majoritné extracelulárne proteíny: extracelulárnu metaloendopeptidázu – bacilolyzín s molekulovou hmotnosťou 33 kDa v koncentrácii 0,01 až 0,05 mg/ml a peptid viažuci proteín pre ABC transportér s molekulovou hmotnosťou 61 kDa v koncentrácii 0,01 až 0,05 mg/ml a ďalšie proteolytické enzýmy, peptidázu...
Book
Full-text available
The acquisition of sufficient knowledge was the chief impetus underlying our writing the scientific monograph The Historical Pipe Organs of Carl Leopold Wegenstein in Slovakia. We collected the information as part of our research over an extended period of time – it is not always possible to look deeper, or to interfere in-depth into historical pip...
Article
Iron, an essential element for most living organism, participates in a wide variety of physiological processes. Disturbance in iron homeostasis has been associated with numerous pathologies, particularly in the heart and brain, which are the most susceptible organs. Under iron-overload conditions, the generation of reactive oxygen species leads to...
Article
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The mechanical properties of thermally stable ultrafine-grained Al metal matrix composites dispersion strengthened and stabilized by nano-metric in-situ Al2O3 (named HITEMAL©) fabricated by powder metallurgy (PM) were tested by small punch testing (SPT) in a broad temperature range from a room temperature (RT) to 500 °C. By changes to PM approach a...
Article
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Diclofenac sodium salt (DSS)-loaded electrospun nanofiber mats on the base of poly(ε-caprolactone) (PCL) were investigated as biocompatible nanofibrous mats for medical applications with the ability to inhibit bacterial infections. The paper presents the characteristics of fibrous mats made by electrospinning and determines the effect of medicament...
Article
The microstructural evolution of an Nb‐Ti microalloyed steel with the application of coiled tubing was studied in detail during hot rolling followed by accelerated cooling and simulated coiling by means of optical microscopy complemented with electron backscattered diffraction and transmission electron microscopy. It was found that the main microst...
Article
The effect of carbon addition and cooling rate on the lamellar structure of peritectic Ti-46.5Al-5Nb-0.2B-0.2C (at.%) alloy was studied. The studied alloys with a carbon content of 0.2, 0.5, 0.7 and 1.0 at.% were prepared by vacuum induction melting in graphite crucibles. The as-cast samples were subjected to solution annealing in a single α (Ti-ba...
Article
Full-text available
Eusociality in its various degrees represents an animal social system characterised by cooperative brood care, differentiation into castes and generational overlap. The fossil record indicates that eusociality is likely to have originated in hymenopterans and blattodeans during the Cretaceous. In this study, we present findings from surveys in Peru...
Article
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Silk fibroin is a biocompatible, non-toxic, mechanically robust protein, and it is commonly used and studied as a material for biomedical applications. Silk fibroin also gained particular interest as a drug carrier vehicle, and numerous silk formats have been investigated for this purpose. Herein, we have prepared electrospun nanofibers from pure s...
Article
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This work presents a simple procedure for the preparation of 2D carbon flakes by a catalyst-free redox reaction in the range of 400–600 °C at atmospheric pressure. Tetrachloromethane (CCl4) was reduced by aluminium flakes (Al), which also serve as a template for carbon flakes, for either 60 min or 120 min. Gaseous aluminium chloride (AlCl3) was rel...
Article
The deformation behavior of bimodal size Al2O3/Al nanocomposites were investigated by hot compression tests conducted in the temperature range 350–500°C and strain rates of 0.001, 0.01 and 0.1 s‐1.The dynamic recrystallization behavior of the nanocomposites strongly depended on the forming parameters. The bimodal sized Al2O3 particles played a cruc...
Article
Full-text available
Powder metallurgy (PM) fabricated HITEMAL is a near- and sub-micrometer aluminum (Al) material that is stabilized by a small fraction of a nano alumina (Al2O3) secondary phase. This phase forms in situ from surface Al2O3 films present on as-atomized Al powders during compaction. HITEMAL showed unique mechanical properties and creep performance at h...
Article
Full-text available
Tantalum diboride (TaB2) belonging to the ultrahigh temperature ceramics family is proving to be a promising material for hard protective films, thanks to its high thermal stability and excellent mechanical properties. However, growth of TaB2 ± x films prepared using physical vapor deposition techniques is strongly affected by Ar neutrals reflected...
Article
Full-text available
Phase composition of AZ61‐SiC composite with 5 wt.% of nanosized silicon carbide reinforcement was analysed and failure mechanism by in situ tensile test in scanning electron microscope was observed. Microstructure of the experimental materials was heterogeneous with grain size of 15 μm. Based on the quantitative analysis of composite, besides, sil...
Article
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Aluminum/CNT nanocomposite sheets, with appropriate dispersion and interfacial bonding, were fabricated by a combination of powder metallurgy, spark plasma sintering (SPS), and hot rolling. The effects of CNT content as well as plastic deformation, on the microstructure and mechanical properties of the obtained nanocomposite, were investigated. The...
Article
In this study, hydroxyapatite (HA) nanoparticles (~120 nm, 3 vol%) are incorporated within a subsurface layer based on commercial pure titanium using multi-step friction-stir processing (FSP) to fabricate an CP-Ti/HA surface nanocomposite. A combination of electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) analyse...
Article
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Samples taken from the human brain ( Globus Pallidus ) have been investigated by physical techniques such as light microscopy, scanning electron microscopy, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. SEM-EDX/TEM investigation reveals multielemental composition of hematite and magnetite nanocrystals with sizes r...
Article
Solid-state butt-joining of powder metallurgy (PM) fabricated Al-Al 2 O 3 nanocomposites was assessed using friction-stir welding (FSW), in which the PM materials were prepared from aluminum powder with different particle size distributions of <9 μm, <63 μm, and <250 μm. After establishing a suitable working window in terms of rotational speed (w)...
Article
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Composite materials based on Cu matrix have a wide range of applications because of their extraordinary features such as high thermal conductivity and high mechanical strength. The preparation of Cu-ZrB2 and CuCr1Zr-ZrB2 composites via gas pressure infiltration technology is described in this work. In contrast to most ceramic materials, ZrB2 is ele...
Article
Full-text available
Composite materials based on Cu matrix have a wide range of applications because of their extraordinary features such as high thermal conductivity and high mechanical strength. The preparation of Cu-ZrB2 and CuCr1Zr-ZrB2 composites via gas pressure infiltration technology is described in this work. In contrast to most ceramic materials, ZrB2 is ele...
Article
Full-text available
Cu/ZrB2 and CuCr1Zr/ZrB2 composites were prepared by gas pressure infiltration technology. The ZrB2 powder was used as reinforcement. No interfacial reaction took place for Cu, or CuCr1Zr matrix as confirmed by transmission electron microscopy (TEM). The thermal stability of composites was very good, i.e. without any indication of possible disinteg...
Preprint
Of coverage-guided fuzzing's three main components: (1) testcase generation, (2) code coverage tracing, and (3) crash triage, code coverage tracing is a dominant source of overhead. Coverage-guided fuzzers trace every testcase's code coverage through either static or dynamic binary instrumentation, or more recently, using hardware support. Unfortun...
Article
Full-text available
Readers should note that there is a phrase missing in the Acknowledgment Section of this article as published:
Conference Paper
The Java platform and its third-party libraries provide useful features to facilitate secure coding. However, misusing them can cost developers time and effort, as well as introduce security vulnerabilities in software. We conducted an empirical study on StackOverflow posts, aiming to understand developers' concerns on Java secure coding, their pro...
Article
Combination of mechanical alloying and friction stir processing was used for the fabrication of Al/(Al13Fe4 + Al2O3) nano-composites. Pre-milled hematite + Al powder mixture was introduced into the stir zone generated on 1050 aluminum alloy sheet by friction stir processing. Uniform and active milled powder mixture reacted with plasticized aluminum...
Article
Full-text available
Java platform and third-party libraries provide various security features to facilitate secure coding. However, misusing these features can cost tremendous time and effort of developers or cause security vulnerabilities in software. Prior research was focused on the misuse of cryptography and SSL APIs, but did not explore the key fundamental resear...
Article
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The Ni-NiO skeleton seems to be a good candidate for various applications in industry such as corrosion-proof filters or components in refrigerating systems and as preforms for reactive infiltration with molten metals.The present work was focused on preparation of Ni-NiO composite with higher, controlled porosity. Sintering of pure Ni powder always...
Article
Full-text available
Cu/ZrB2 composite was prepared by gas pressure infiltration of molten metal into ceramic preform. Microstructure and erosion resistance of composite was investigated. The microstructure was analysed by light microscopy and scanning electron microscopy. The chemical compositions were analysed using energy dispersive X-ray spectroscopy. Good penetrat...
Article
The aim of the work is to study interface formation between Al 2 O 3 particles and Al(Ca) matrix in dependence of Ca content. Aluminium matrix composites (AMC) subjected to investigation were prepared by gas pressure assisted infiltration of alumina beds with aluminium-calcium alloys .. It is shown that alumina particles in the AMC are covered with...
Article
Full-text available
In situ observation of AZ61 Mg alloy with 5 wt. % of Al2O3 in the SEM was performed to study influence of the weight fraction of Al2O3 particles on the deformation and fracture description during the tensile test. Structure of the experimental materials was also analysed; microstructures were heterogeneous, with randomly distributed globular Al2O3...
Article
Full-text available
In situ observation of AZ61 Mg alloy with 1 and 5 wt% of Al2O3 in the scanning electron microscopy was performed to study influence of the weight fraction of Al2O3 particles on the deformation and fracture mechanism during tensile test. Structure of the experimental materials was also analysed; microstructures were heterogeneous, with randomly dist...
Article
Full-text available
The ablation resistance of Cu and Cu/Al2O3 subjected to 200 spark discharges was compared in this work. It appears that the volume lost in the course of sparking was 6 times higher for Cu than for Cu/Al2O3 composite. Linear dependences of the amount of loss material on the number of electrical discharge analytical cycles for Cu/Al2O3 composite mate...
Article
The work is focused to prepare Al based master-alloy pellet with 50 vol.% of Al2O3 for subsequent manufacturing of aluminum matrix composites with desired amount of reinforcement (5–20%). Since master-alloy is manufactured via pressure infiltration and proper interface between particles and melt is required for uniform particle distribution within...
Article
Full-text available
Nickel aluminides exhibit very attractive high temperature properties. However, due to high melting temperatures they are difficult to prepare. Gas pressure reactive infiltration is a relatively cheap technology that provides composites where nickel aluminides are formed due to mutual reaction between Ni powder and molten aluminium forced to penetr...

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