Nanoscale Porosity of High Surface Area Gadolinium Oxide Nanofoam Obtained With Combustion Synthesis

Nanoscale gadolinium oxide (Gd2O3) is a promising nanomaterial with unique physicochemical properties that finds various applications ranging from biomedicine to catalysis. The preparation of highly porous Gd2O3 nanofoam greatly increases its surface area thereby boosting its potential for functional use in applications such as water purification processes and in catalytic applications. By using the combustion synthesis method, a strong exothermic redox reaction between gadolinium nitrate hexahydrate and glycine causes the formation of crystalline nanoporous Gd2O3. In this study, the synthesis of Gd2O3 nanofoam is achieved with combustion synthesis at large scale (grams). Its nanoscale porosity is investigated by nitrogen physisorption and its nanoscale 3D structure by electron tomography, and the formation process is investigated as well by means of in situ heating inside the transmission electron microscope. The bulk nanofoam product is highly crystalline and porous with a surface area of 67 m2 g−1 as measured by physisorption, in good agreement with the electron tomographic 3D reconstructions showing an intricate interconnected pore network with pore sizes varying from 2 to 3 nm to tens of nanometers. In situ heating experiments point to many possibilities for tuning the porosity of the Gd2O3 nanofoam by varying the experimental synthesis conditions

Mechanics of screw joints solved as beams placed in a tangential elastic foundation

This article deals with a new original analytical solution of deformation, force and stress states in wood screw joints up to the limit values of pulling out/breaking the screw. The screws are under tension. The wood-to-screw interaction is effectively simplified by introducing several physical model variants using a tangential elastic non-linear foundation. The experimental verification of the proposed models using pull-out tests (i.e., pulling out screws from dry spruce wood in laboratory conditions) confirms the correctness of the proposed models of the elastic linear/non-linear foundation. The validity of the model is also analytically and experimentally verified in the biomechanical model of pulling out screws from the femur of a bovine/human cadaver, which confirms and expands the validity of newly designed screw joint models outside the timber structure area.Web of Science1112art. no. 561

Analysis and modelling of single domain core-shell (αFeNi/chromite) nanoparticles emitted during selective laser melting, and their magnetic remanence

Despite recent intense implementation of increasingly eco-friendly additive manufacturing, the properties of nanoparticulate pollutants emitted during Laser Powder Bed Fusion are still not fully understood, and have generally been overlooked. This study aims to fill this gap in current research by providing new insights into distinct metal/oxide core-shell nanoparticles (3–36 nm) that are produced during 3D printing using stainless steel. It also suggests possible ways for the removal of these potentially harmful by-products. Further, this research also provides a newly developed kinetic model that predicts a metal core growth time of below 200 μs and confirms the predicted theory for the formation of these by-products. In the current study it was found that the cores produced during this process are purely metallic and consist of meteoroid phase kamacite (αFeNi). Within this study there was found to be a complete dominance of single-domain cores of kamacite with prevailing particles below the superparamagnetic threshold showing strong magnetic response and remanence. This new knowledge can be used to minimize potential health risks and reduce contamination of raw materials by this nanoparticulate pollutant, which can adversely affect the quality of printed metal parts, the environment, and the health of the operator. These findings also provide a new possibility of targeted efficient production of superparamagnetic core-shell nanoparticles with a metallic kamacite core during laser powder bed fusion of austenitic steel 316L powder, which can be used in the production of sensors.Web of Science400art. no. 13668

Selected nano- and micro-sized metal oxides: properties, applications and their presence in the environment

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Oxide nanolayer formation on surface of modified blast furnace sludge particles during voltammetric cycling in alkaline media

Knowledge of the properties of metallurgical waste is essential for the assessment of their recycling. In this work, the formation of iron oxide nanolayers during voltammetric cycling in 1 M NaOH on the particle surface of blast furnace sludge after acid leaching (BFSL) was studied. Most importantly, the effect of hydrogen on these processes was of particular interest. For these purposes, the study combines electrochemical methods, cyclic voltammetry on solid and carbon paste electrodes, with analytical optical methods (TEM). On the solid iron electrode surface as a model system, nanostructured magnetite (Fe3O4) was identified as the main oxidation product, and, to a lesser extent, also maghemite (gamma-Fe(2)0(3)). It was found that the charges corresponding to Fe(3)O(4)formation and its reduction together with the hydrogen evolution reaction (HER) occurring atE = - 1500 mV depend on the number of cycles and have a similar course. Additionally, in the first phase of the cycling, the accumulation of maghemite on the solid Fe-electrode surface during cycling affects the growth of the oxide layer and catalytically increases the yield of the HER. Concerning the measurement with BFSL-modified CPE, on the BFSL surface, haematite is transformed into magnetite during cycling, resulting in the same Fe(3)O(4)nanolayer as on the solid iron electrode. In this layer, the same redox processes take place, including the influence of hydrogen in the initial stage of cycling.Web of Scienc

Nanoscale Porosity of High Surface Area Gadolinium Oxide Nanofoam Obtained With Combustion Synthesis

Abstract Nanoscale gadolinium oxide (Gd2O3) is a promising nanomaterial with unique physicochemical properties that finds various applications ranging from biomedicine to catalysis. The preparation of highly porous Gd2O3 nanofoam greatly increases its surface area thereby boosting its potential for functional use in applications such as water purification processes and in catalytic applications. By using the combustion synthesis method, a strong exothermic redox reaction between gadolinium nitrate hexahydrate and glycine causes the formation of crystalline nanoporous Gd2O3. In this study, the synthesis of Gd2O3 nanofoam is achieved with combustion synthesis at large scale (grams). Its nanoscale porosity is investigated by nitrogen physisorption and its nanoscale 3D structure by electron tomography, and the formation process is investigated as well by means of in situ heating inside the transmission electron microscope. The bulk nanofoam product is highly crystalline and porous with a surface area of 67 m2 g−1 as measured by physisorption, in good agreement with the electron tomographic 3D reconstructions showing an intricate interconnected pore network with pore sizes varying from 2 to 3 nm to tens of nanometers. In situ heating experiments point to many possibilities for tuning the porosity of the Gd2O3 nanofoam by varying the experimental synthesis conditions

Stochastic strength analyses of screws for femoral neck fractures

This paper represents a multidisciplinary approach to biomechanics (medicine engineering and mathematics) in the field of collum femoris fractures, i.e., of osteosyntheses with femoral/cancellous screws with full or cannulated cross-sections. It presents our new numerical model of femoral screws together with their stochastic (probabilistic, statistical) assessment. In the first part of this article, the new simple numerical model is presented. The model, based on the theory of planar (2D) beams on an elastic foundation and on 2nd-order theory, is characterized by rapid solution. Bending and compression loadings were used for derivation of a set of three 4th-order differential equations. Two examples (i.e., a stainless-steel cannulated femoral screw and full cross-section made of Ti6Al4V material) are presented, explained, and evaluated. In the screws, the internal shearing forces, internal normal forces, internal bending moments, displacement (deflections), slopes, and mechanical stresses are calculated using deterministic and stochastic approaches. For the stochastic approach and a "fully" probabilistic reliability assessment (which is a current trend in science), the simulation-based reliability assessment method, namely, the application of the direct Monte Carlo Method, using Anthill software, is applied. The probabilities of plastic deformations in femoral screws are calculated. Future developments, which could be associated with different configurations of cancellous screws, nonlinearities, experiments, and applications, are also proposed.Web of Science123art. no. 101

Simple fabrication of polycaprolactone-co-lactide membrane with silver nanowires: Synthesis, characterization and cytotoxicity studies

Our simple technique of polymer/metal-based material preparation produces very promising material, and we outline that this material can be suitable for the potential wound healing multilayered dressing. In our research we focused on these main issues: (1) the preparation of silver nanowire-like structures using gallic acid (GA); (2) direct silver nanowire-like structure crystallization of co-polymer L-lactide and epsilon-caprolactone (PLCL) electrospun fiber and (3) evaluation of the material cytotoxicity on the Vero cell line. Synthesized silver nanowire-like width varied from 30 to 100 nm and the hexagonal particles had sizes from 80 to 300 nm. The detected structures were crystalline cubic silver and were similarly synthesized during both batch synthesis and direct synthesis on the PLCL fibers. The amount of the silver spread within the fibrous membrane was approximately 1.1 wt. % in the sample, moreover, the silver incorporation had no influence on the polymer structure, which was confirmed by FTIR measurement. The cytotoxicity testing estimated that cell survival increased with decreased concentration of GA and silver in the PLCL matrix and the silver-based sample in 50 % MTT extraction concentration maintained required non-cytotoxic properties.Web of Science23112993298

Biomechanical analysis of staples for epiphysiodesis

Limb asymmetry can, and often does, cause various health problems. Blount bone staples (clips) are used to correct such uneven growth. This article analyzes the performance of a biomechanical staple during bone (tibia) growth arrest. The staples considered in this study were made of 1.4441 stainless steel, the model of tibia consisted of two materials representing corticalis and spongiosis. Hooke's law was used for modeling materials' behaviors for finite element analysis (FEA). The maxima of stress and total staple displacement were evaluated using the finite element method and verification of the results, along with the determination of the maximum loading (growing) force that the staples are capable of withstanding, was performed experimentally. The presented method can be used to determine the safety and usability of staples for bone growth arrest. According to our results, the design of Blount staples considered in this paper is safe and suitable for orthopedic treatment.Web of Science122art. no. 61