Support Surface Research Articles

Low-Energy Ion Scattering Intensities from Supported Nanoparticles: The Spherical Cap Model

Supported nanoparticles are of great importance to many technologies like fuel processing and chemical synthesis using catalysts and electrocatalysts, energy storage and generation using fuel cells and batteries, electrochemistry, magnetic information storage, and more. Low-energy ion scattering spectroscopy (LEIS) with noble gas ions like He+ is a powerful tool for the characterization of nanoparticles dispersed across flat support surfaces due to its ability to probe the elemental composition in the topmost atomic layer of a surface, providing quantitative information regarding the size and number density of nanoparticles. In this work, we present a derivation of the LEIS intensities expected from nanoparticles and the support material as a function of the average particle size, their number per unit area, and their contact angle with the support when modeled as spherical caps of the nanoparticle material dispersed over the surface of a flat support. The model assumes that the ion intensities are determined only by the physical blocking of linear ion trajectories and independent of the tilt angle of the local surface relative to the incident and scattered ion directions, an assumption we support by quantitative modeling of published data which tested tilt-angle effects. The model is a generalization to arbitrary contact angles of the hemispherical cap model, which assumes 90° contact angle and has been widely used to model spectroscopic signals in LEIS (and also in Auger and photoelectron spectroscopies) during nanoparticle growth. This new model quantitatively reveals how LEIS signals are sensitive not only to the diameter and number density of the nanoparticle but also to their contact angle (or height/diameter ratio). With the use of additional data (e.g., from microscopy or adsorption microcalorimetry), the model presented here will enable more accurate determination of the average size, shape, and number density of supported nanoparticles based on LEIS intensity measurements.

Single‐Atom Fe Catalyst for Catalytic Ethane Dehydrogenation to Ethylene

AbstractThe single atom catalysts (SACs) show unique catalytic performance in heterogeneous reactions owing to unsaturated coordination sites and high metal atom dispersion. Herein, a simple wet impregnation method was utilized to synthetize of Fe−Al2O3 catalysts. The Fourier transformation infrared spectroscopy (FTIR) revealed that abundant OH group attached to the support (Al2O3) surface facilitating formation of isolated Fe single atom. High resolution transmission electron microscope (HR‐TEM) and extended X‐ray absorption fine structure (EXAFS) confirmed the Fe single atom architecture. Fe−Al2O3 (4.5 wt %) performed enhanced stability and activity on ethane dehydrogenation reaction.

Highly dispersed Pt–MnOx nanoclusters for the promoted activity of mesoporous Pt–MnOx–Al2O3 in dehydrogenation of perhydro-benzyltoluene

Pt single atom is vulnerable to sintering under endothermic reaction conditions and sometimes shows low activity in the conversion of bulky molecules, e.g., dehydrogenation of perhydro-benzyltoluene (H12-BT) for the state-of-the-art liquid organic hydrogen carrier system. Such weakness has been tackled using various approaches including Pt nanoclustering with metal oxide(s). We herein describe the excellence of mesoporous Pt–MnOx–Al2O3 (mPtMnA) in H12-BT dehydrogenation, where solvent-deficient precipitation (SDP) is employed for catalyst preparation. When prepared at the Mn/Pt molar ratio of 0.33 and the ramp of 10 °C min−1 in H2 reduction, the catalyst (named mPt0.33MnA_r10) affords the best efficiency of 94 % H2 yield. This results from highly dispersed Pt–MnOx nanoclusters generated by the surface diffusion of Pt atoms to oxophilic Mn oxides distributed homogeneously on the surface of support. Consequently, this study demonstrates that the SDP method favors Pt nanoclustering with MnOx, which will greatly impact on dehydrogenation catalysis.

Self-oxidation of Au-[Bmim][Cl3] catalyst with enhanced activity and stability for acetylene hydrochlorination

There is great potential for carbon-supported gold catalysts to replace toxic mercuric chloride-based catalysts in the acetylene hydrochlorination, which is a key process for producing PVC. However, the catalyst design is essentially hindered by the difficulties in enhancing the catalytic activity of cationic gold and suppressing the deactivation of active species. We report a strategy for self-oxidation of Au3+ by the Au-SILP system with the [Bmim][Cl3] ILs. This strategy can stabilize all gold species in the state of highly oxidized Au3+ instead of coexisting in the Au3+/Au+ site, which makes the catalyst exhibit excellent catalytic activity. High coordination numbers Au-Cl entities reduce the electron transfer between Au3+ and C2H2 and weaken the adsorption of C2H2 on the Au active sites. Furthermore, [Bmim][Cl3] ILs can self-oxidize gold nanoparticles on the support surface into Au3+. This study provides a new method for improving the stability and activity of gold-based acetylene hydrochlorination catalysts.

N-doped porous carbon-anchored zinc single-atom as an efficient and robust heterogeneous catalyst for glycerol carbonylation with urea

Constructing highly efficient and stable heterogeneous catalysts for glycerol carbonylation is a very significant subject for its importance in promoting the development of biodiesel industry. Herein, a carbon-based single-Zn-atom catalyst (Zn1/NC) was prepared by using N-doped porous carbon material (NC) as support via a wet impregnation technique, following a thermal treatment at 600 °C. Various characterization results demonstrate that Zn2+ cations are atomically dispersed on the surface of NC support by coordination with the existed N- and O-containing groups. The Zn1/NC catalyst exhibited outstanding catalytic activity, selectivity and stability for glycerol carbonylation with urea at mild conditions. Operando ReactIR spectra results show that urea molecules could be easily activated by the single-atom Zn catalyst then react with glycerol molecules to generate the main product of glycerol carbonate via an intermediate of 2,3-dihydroxypropyl carbamate. Density functional theory calculations reveal that NC support could provide a unique coordination environments for the single-atom site of Zn2+, which can guarantee the preferential adsorption of urea molecule (rather than glycerol) and effectively inhibit the generation of the unfavorable Zn-glycerol complex, thus leading to the formation of highly efficient and robust heterogeneous catalyst for glycerol carbonylation with urea.

How Solid Surfaces Control Stability and Interactions of Supported Cationic CuI(dppf) Complexes─A Solid-State NMR Study

Organometallic complexes are frequently deposited on solid surfaces, but little is known about how the resulting complex-solid interactions alter their properties. Here, a series of complexes of the type Cu(dppf)(Lx)+ (dppf = 1,1'-bis(diphenylphosphino)ferrocene, Lx = mono- and bidentate ligands) were synthesized, physisorbed, ion-exchanged, or covalently immobilized on solid surfaces and investigated by 31P MAS NMR spectroscopy. Complexes adsorbed on silica interacted weakly and were stable, while adsorption on acidic γ-Al2O3 resulted in slow complex decomposition. Ion exchange into mesoporous Na-[Al]SBA-15 resulted in magnetic inequivalence of 31P nuclei verified by 31P-31P RFDR and 1H-31P FSLG HETCOR. DFT calculations verified that a MeCN ligand dissociates upon ion exchange. Covalent immobilization via organic linkers as well as ion exchange with bidentate ligands both lead to rigidly bound complexes that cause broad 31P CSA tensors. We thus demonstrate how the interactions between complexes and functional surfaces determine and alter the stability of complexes. The applied Cu(dppf)(Lx)+ complex family members are identified as suitable solid-state NMR probes for investigating the influence of support surfaces on deposited inorganic complexes.

Stabilization of a Carbon Support by Surface Oxygen with Respect to Nitrogen Dioxide in the Pd/HOPG Model System

X-ray photoelectron spectroscopy (XPS) method has been used to study the effect of oxygen on the surface of a carbon support on the result of NO2 interaction with model systems prepared by evaporation of palladium on highly oriented pyrolytic graphite (HOPG). For Pd/HOPG samples with an atomic ratio [O]/[C] ≤ 0.0035, graphite oxidized with the destruction of its structure to a depth of 10–15 graphene layers. In this case, palladium particles remained in the metallic state and penetrated into the subsurface layer of the support due to the deep oxidation of the adjacent carbon atoms. At the atomic ratio [O]/[C] ≈ 0.01–0.02, the result of the interaction changed dramatically. In this case, the HOPG remained stable, and the palladium particles were oxidized to form an oxide. This finding explained the high stability of supported palladium catalysts prepared on Sibunit carbon supports in reactions of oxidation catalysis.

Studies on High-Temperature Evolution of Low-Loaded Pd Three-Way Catalysts Prepared by Laser Electrodispersion.

Pd/Al2O3 catalyst of the "crust" type with Pd loading of 0.03 wt.% was prepared by the deposition of 2 nm Pd particles on the outer surface of the alumina support using laser electrodispersion (LED). This technique differs from a standard laser ablation into a liquid in that the formation of monodisperse nanoparticles occurs in the laser torch plasma in a vacuum. As is found, the LED-prepared catalyst surpasses Pd-containing three-way catalysts, obtained by conventional chemical synthesis, in activity and stability in CO oxidation under prompt thermal aging conditions. Thus, the LED-prepared Pd/Al2O3 catalyst showed the best thermal stability up to 1000 °C. The present research is focused on the study of the high-temperature evolution of the Pd/Al2O3 catalyst in two reaction mixtures by a set of physicochemical methods (transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance UV-vis spectroscopy). In order to follow the dispersion of the Pd nanoparticles during the thermal aging procedure, the testing reaction of ethane hydrogenolysis was also applied. The possible reasons for the high stability of LED-prepared catalysts are suggested.

Correction to: 'Assessing the stability of human locomotion: a review of current measures' (2013) by Bruijn et al.

Open AccessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Bruijn S. M., Meijer O. G., Beek P. J. and van Dieën J. H. 2023Correction to: ‘Assessing the stability of human locomotion: a review of current measures’ (2013) by Bruijn et al.J. R. Soc. Interface.202023020720230207http://doi.org/10.1098/rsif.2023.0207SectionOpen AccessCorrectionCorrection to: ‘Assessing the stability of human locomotion: a review of current measures’ (2013) by Bruijn et al. S. M. Bruijn S. M. Bruijn http://orcid.org/0000-0003-0290-2131 Google Scholar Find this author on PubMed Search for more papers by this author , O. G. Meijer O. G. Meijer http://orcid.org/0000-0002-8394-6859 Google Scholar Find this author on PubMed Search for more papers by this author , P. J. Beek P. J. Beek http://orcid.org/0000-0002-0917-8548 Google Scholar Find this author on PubMed Search for more papers by this author and J. H. van Dieën J. H. van Dieën http://orcid.org/0000-0002-7719-5585 Google Scholar Find this author on PubMed Search for more papers by this author S. M. Bruijn S. M. Bruijn http://orcid.org/0000-0003-0290-2131 Google Scholar Find this author on PubMed Search for more papers by this author , O. G. Meijer O. G. Meijer http://orcid.org/0000-0002-8394-6859 Google Scholar Find this author on PubMed Search for more papers by this author , P. J. Beek P. J. Beek http://orcid.org/0000-0002-0917-8548 Google Scholar Find this author on PubMed Search for more papers by this author and J. H. van Dieën J. H. van Dieën http://orcid.org/0000-0002-7719-5585 Google Scholar Find this author on PubMed Search for more papers by this author Published:03 May 2023https://doi.org/10.1098/rsif.2023.0207This article corrects the followingReview ArticleAssessing the stability of human locomotion: a review of current measureshttps://doi.org/10.1098/rsif.2012.0999 S. M. Bruijn, O. G. Meijer, P. J. Beek and J. H. van Dieën volume 10issue 83Journal of The Royal Society Interface06 June 2013 J. R. Soc. Interface 10, 20120999. (Published online 6 June 2013) (https://doi.org/10.1098/rsif.2012.0999) An attentive reader pointed out a mistake in our paper. On page 6 the paper reads ‘Chang et al. [95] reported that walking over an unstable support surface increases values of λS, but not of λL.’, which actually should have read: ‘Chang et al. [95] reported that walking over an unstable support surface decreases values of λL, but not of λS.’. This mistake does not further influence the conclusions we reach regarding these stability measures. Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesAssessing the stability of human locomotion: a review of current measures06 June 2013Journal of The Royal Society Interface This IssueMay 2023Volume 20Issue 202 Article InformationDOI:https://doi.org/10.1098/rsif.2023.0207PubMed:37132230Published by:Royal SocietyOnline ISSN:1742-5662History: Manuscript received11/04/2023Manuscript accepted11/04/2023Published online03/05/2023 License:© 2023 The Authors.Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Citations and impact Subjectsbiomechanics

Assessment of the risk factors for intraoperative pressure injuries in patients

AimThis study was conducted to assess the risk factors for pressure injuries in patients during surgery. MethodsIn this descriptive cross-sectional study, the risk of pressure injuries during surgery was evaluated in 250 patients in a university hospital. Data were collected through a Patient Descriptive Information Form (PDIF) and the 3S Intraoperative Pressure Injury Risk Assessment Scale (IPIRAS). ResultsThe mean age of the patients was 44.15 ± 17.00, and 52.4% were female. In addition, it was determined that the mean 3S IPIRAS score was higher in patients who were male, were aged ≥60 years, were obese, had a chronic disease, and had low serum albumin and hemoglobin levels (p < .05). During the surgery of the patients included in the study, support surfaces were used in 67.6%, positioning aids were used in 82.4%, and 55.6% had normal skin. Patients who underwent CVS procedures for more than 6 h, did not use support surfaces during surgery, had moist skin, or used vasopressors had higher and significantly different mean 3S IPIRAS scores (p < .05). ConclusionsAccording to the results, all surgical patients were at risk for pressure injury in the intraoperative period. In addition, it was found that male gender was associated with risk factors and that being aged ≥60 years, obesity, chronic disease, low serum hemoglobin and albumin levels, CVS, operations lasting more than 6 h, moist skin, vasopressor drugs, and not using support surfaces during surgery increased the risk of pressure injuries significantly.

Evolution of copper species during heat treatment and its effect on CO oxidation reaction on CuCeZrOy catalyst synthesized by a facile solvent-free route

Several ternary oxides CuCeZrOy (CCZ) were synthesized by a facile grinding method followed by calcination at high temperatures, and used as catalysts for CO oxidation at low temperatures. The influences of calcination temperature (400–600 °C) on the physicochemical properties of the as-synthesized ternary oxides were investigated by thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, inductively coupled plasma-optical emission spectrometry (ICP-OES), N2 adsorption, H2-temperature programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) characterizations. The results show that the increase in calcination temperature from 400 to 500 °C is conducive to the high dispersion of CuOx on catalyst surface and the incorporation of Cu species into the support to form the Cu–Ce–Zr–O solid solution. Further raising of calcination temperature from 500 to 600 °C, however, leads to the segregation of Cu species from the solid solution to aggregate on support surface and growth of highly dispersed CuOx nanoparticles. The highest catalytic activity is acquired over the CCZ calcined at 500 °C, which can be ascribed to the largest contents of Cu+ species and oxygen vacancies owing to the formation of the maximum amount of Cu–Ce–Zr–O solid solution.

The biomechanical efficacy of a hybrid support surface in protecting supine patients from sacral pressure ulcers.

Support surfaces are the most important pressure ulcer/injury prevention technology available to clinicians for protecting their at-risk patients. A hybrid support surface marries the benefits of reactive and active support surfaces, by using high-quality foam material inside inflatable air cells. When used in its "static mode", it is a constant low air pressure mattress which delivers pressure redistribution in response to patient bodyweight and movements, by maximising the immersion and envelopment performance of the support surface. When used in its powered "dynamic mode", this system further delivers alternating pressure care via the connected foam and air cells. Modes of action of hybrid support surfaces were never studied quantitatively before, excluding through the limited scope of interface pressure mapping. In this work, we developed a novel computational modelling framework and simulations to visualise and quantify the state of soft tissue loading at the buttocks of a supine patient positioned on a hybrid support surface, in both the static and dynamic modes. We found that the dynamic mode effectively shifts deep concentrated soft tissue loading from under the sacral bone (towards the sacral promontory) to the tip of the sacrum (coccyx) and vice versa, and thereby, generates a deep tissue offloading effect.

Plasma-assisted synthesis of ZIF-8 membrane for hydrogen separation

Well-intergrown MOF membranes were challenging to construct using the in-situ approach, due to the poor heterogeneous nucleation of MOF on the supports. Here, we described a technique to manufacture ZIF-8 membranes devoid of induced seeds using support modified by O2 plasma for the first time. O2 plasma can increase the number of oxygen-containing functional groups (–OH) on the support surface that could absorb zinc ions from synthesizing solution and offer heterogeneous nucleation sites for the formation of ZIF-8 membranes. The as-synthesized membrane exhibits outstanding gas permeation performance with a high hydrogen permeance of about 2.22 × 10−7 mol·m−2·s−1·Pa−1 and a high H2/CH4 ideal selectivity of 25.91. The separation factor of the equimolar H2/CO2 and H2/CH4 mixtures reached 8.72 and 31.03 at 298 K and 0.1 MPa, respectively. In addition, this new technique also allowed for the synthesis of ZIF-67 membranes, and the prepared membrane had an H2/CH4 ideal selectivity of 14.92. This work develops a new route for the efficient fabrication of MOF membranes.

A Universal Adaptable Support Surface with Reversible Adaptation and Adjustable Rigidity for Dental Chairs

A Universal Adaptable Support Surface with Reversible Adaptation and Adjustable Rigidity for Dental Chairs

Time-Resolved Formation and Operation Maps of Pd Catalysts Suggest a Key Role of Single Atom Centers in Cross-Coupling.

An approach to the spatially localized characterization of supported catalysts over a reaction course is proposed. It consists of a combination of scanning, transmission, and high-resolution scanning transmission electron microscopy to determine metal particles from arrays of surface nanoparticles to individual nanoparticles and individual atoms. The study of the evolution of specific metal catalyst particles at different scale levels over time, particularly before and after the cross-coupling catalytic reaction, made it possible to approach the concept of 4D catalysis-tracking the positions of catalytic centers in space (3D) over time (+1D). The dynamic behavior of individual palladium atoms and nanoparticles in cross-coupling reactions was recorded with nanometer accuracy via the precise localization of catalytic centers. Single atoms of palladium leach out into solution from the support under the action of the catalytic system, where they exhibit extremely high catalytic activity compared to surface metal nanoparticles. Monoatomic centers, which make up only approximately 1% of palladium in the Pd/C system, provide more than 99% of the catalytic activity. The remaining palladium nanoparticles changed their shape and could move over the surface of the support, which was recorded by processing images of the array of nanoparticles with a neural network and aligning them using automatically detected keypoints. The study reveals a novel opportunity for single-atom catalysis─easier detachment (capture) from (on) the carbon support surface is the origin of superior catalytic activity, rather than the operation of single atomic catalytic centers on the surface of the support, as is typically assumed.

Design model of radial bearing with bearing sleeve elastic bearing profile and metal coated shaft surface

The article is devoted to the development and analysis of a design model of lubricant movement in the working gap of a radial journal bearing with an elastic bearing profile of the bearing sleeve surface and a metal coating of the shaft surface with truly viscous properties. New mathematical models have been developed based on basic equations that take into account the flow of a truly viscous liquid for a “thin layer”, the malleability of the bearing sleeve support surface - the Lame equation, compressibility - the equation of state, the Weisbach - Darcy formula, the profile of the molten contour of the metal coating of the shaft surface - the rate of dissipation of mechanical energy. The results of the numerical analysis of the refined models obtained by changing the design of the radial bearing, as well as taking into account the compressibility of the lubricant and the coating melt, allowed us to obtain an effectiveness qualitative assessment of the malleable bearing profile of the bearing sleeve and the shaft with a metal coating. A comparative analysis of the obtained results of theoretical and experimental studies of radial bearing structures: with and without metal coating; elastic support profile; without taking into account the elasticity of the support profile; taking into account compressibility; without taking into account the compressibility of the lubricant. At the end of the research complex, experimental tests were carried out that confirmed the correctness of the results of theoretical studies. The ingenuity of the developed design models, taking into account the use of additional lubrication with a metal coating on the shaft surface to compensate for an emergency shortage of lubricant, the compressibility of the lubricant, as well as the malleability of the bearing surface, consists in the application of a technique for obtaining their exact self-similar solutions. As a result of theoretical, experimental research and comparative analysis of the available scientific results with the obtained ones, it was found that the use of the studied radial journal bearings, taking into account the above factors, significantly increases the bearing capacity (8-9 %), and the coefficient of friction decreases by 7…8 %.

IrO2 as a promising support to boost oxygen reduction reaction on Pt in acid under high temperature conditions.

Metal oxide nanoparticle (NP) supports of both good conductivity and stability have the potential to enhance both the reaction activity and stability of the loaded electrocatalysts. In this paper, a facile two-step approach to disperse Pt nanoparticles on the surface of an IrO2 NP support (Pt/IrO2) was developed. Physical characterization by x-ray diffraction spectroscopy and transmission/scanning electron microscopy suggests a good dispersion of the Pt NPs. The temperature effect (from 293 to 353K) of oxygen reduction reaction on Pt/IrO2 was studied by using a rotating ring disk electrode The results show that although the kinetic current density on Pt/IrO2 is close to that on commercial Pt/C at room temperature, the apparent activation energy (Ea,app) in the former case is much lower, suggesting a much higher activity at elevated temperatures. The superiority in Ea,app is attributed to the electron interaction between Pt and the IrO2 support, as supported by the change of surface chemical state given by x-ray photo-electron spectroscopy.

Support Nano‐Co/CeO2‐δ Catalyst for CO2 Hydromethanation

AbstractThe large‐scale use of fossil fuels had resulted in massive emission of CO2 and a series of serious environmental problems, which directly threatening human survival and sustainable development. CO2 is also the abundant carbon resource in C1 family. CO2 catalytic hydrogenation to CH4 is one of the effective ways to ultilize CO2 with low energy and high efficiency, which has been widely concerned in recent years. Suppoted nano‐Co/CeO2‐δ catalysts were prepared and evaluated their CO2 hydrogenation performances. XRD, H2‐TPR, H2‐TPD and CO2‐TPD had been conducted to study the physicochemical properties of the prepared Co/CeO2‐δ catalysts. The Co loading significantly affects the physicochemical properties and CO2 hydrogenation performances. The active metal Co species were highly diepersed on the CeO2 support surface. The number of active metal Co species, which formed by H2 reduction, increased with the increasing of Co loading. And the ability to adsorb and activate the reactant H2 and CO2 molecules was also enhanced, which effectively promoted the CO2 hydrogenation performances. Among of the studied Co/CeO2‐δ catalysts, the CoCe09 catalyst with Co loading of 9 % showed the best CO2 catalytic hydrogenation activity. In the reaction temperature of 240–400 °C, the CO2 conversion and CH4 selectivity follow the order: CoCe01&lt;CoCe03&lt;CoCe05&lt;CoCe11&lt;CoCe09. At 400 °C, the CO2 conversion increases from 30.1 % (CoCe01) to 59.2 % (CoCe09).

THE STRUCTURAL ANALYSIS OF THE HOUSING OF THE FREIGHT CAR AXLE BOX

The cars that are operated on the railways of Ukraine are equipped with axle boxes with cylindrical roller bearings. Many years of operating experience has shown that they have insufficient durability. One of the reasons is the uneven distribution of the load between the rollers in the bearings, caused by the design features of the wagon bogies. One of the possible ways to equalize the distribution of loads between the rolling elements can be the creation of a box housing with variable stiffness. The article provides a detailed analysis of existing design solutions. It has been established that the use of aluminum alloys for the manufacture of axle box housings, despite the low specific density of the alloy, is impractical due to their high cost, increased wear of the bearing surfaces, and insufficient service life. The use of rubber as gaskets to create variable stiffness also proved to be impractical. The reason is the inability of rubber to operate at low temperatures in winter. As a result, the destruction of the rubber required additional (unscheduled) axle box repairs. The manufacture of axle box bodies with cavities or grooves of various configurations in order to change the rigidity of the elements of the upper part of the axle box body turned out to be unpromising. The reason was the technological complexity of manufacturing, the difficulty of providing the necessary strength under dynamic loading conditions. The most successful was the design of the box body with two rectangular tides along the edges of the upper part in the roller loading zone. These lugs are located along the entire length of the hull and are the supporting surfaces for transferring the load from the side frame. A promising direction in the 70s of the XX century was the rejection of traditional massive axle boxes and the transition to the use of adapters (half axle boxes). However, this option had to be abandoned at that time due to the impossibility of ensuring reliable sealing of the bearings. At the same time, the modern experience of American railways shows that one of the promising areas for improving the design of roller axle boxes is the use of adapters in freight bogies of wheelsets equipped with cassette bearings. The adapter redistributes the load from the bogie to the cassette bearing, acts as a supporting part of a conventional axle box and limits the longitudinal, transverse and angular shifts of the wheel set relative to the bogie frame. In addition, the adapter allows you to reduce the tare weight of the car. However, the use of adapters is possible only if the bearings themselves are reliably sealed. Also, a promising direction can be considered the creation of a box body with variable stiffness, including the use of rubber-metal elements. Keywords: freight car, axle box, housing, bearing, adapter, support surface, actuation.

Abrading-Induced Breakdown of Ag Nanoparticles into Atomically Dispersed Ag for Enhancing Antimicrobial Performance

Silver is among the most essential antimicrobial agents. Increasing the efficacy of silver-based antimicrobial materials will reduce operating costs. Herein, we show that mechanical abrading causes atomization of Ag nanoparticles (AgNPs) into atomically dispersed Ag (AgSAs) on the surfaces of an oxide-mineral support, which eventually boosts the antibacterial efficacy considerably. This approach is straightforward, scalable, and applicable to a wide range of oxide-mineral supports; additionally, it does not require any chemical additives and operates under ambient conditions. The obtained AgSAs-loaded γ-Al2O3 inactivated Escherichia coli (E. coli) five times as fast as the original AgNPs-loaded γ-Al2O3. It can be utilized over 10 runs with minimal efficiency loss. The structural characterizations indicate that AgSAs exhibit a nominal charge of 0 and are anchored at the doubly bridging OH on the γ-Al2O3 surfaces. Mechanism studies demonstrate that AgSAs, like AgNPs, damage bacterial cell wall integrity, but they release Ag+ and superoxide substantially faster. This work not only provides a simple method for manufacturing AgSAs-based materials but also shows that AgSAs have better antibacterial properties than the AgNPs counterpart.