A tribological study of (2‐sulphurone‐benzothiazole)‐3‐methyl‐dibutyl borate

An organic compound containing S, N, B, and O was synthesised by reacting 2‐mercaptobenzothiazole and formalin in ethanol solution, the resulting product then being reacted with butanol and boric acid in toluene solution. The tribological performance of the novel compound when added to liquid paraffin was evaluated using a four‐ball tester and a ring‐on‐block machine. The relationship between performance and concentration was analysed, and the results show that the compound possesses good antiwear and load‐carrying abilities. The mechanism of action of the additive was investigated using X‐ray photo‐electron spectroscopy (XPS). Surface analysis indicated the formation of a protective film containing FeSO₄, an organo‐sulphur compound, FeS₂, borate, and an organonitrogen compound. This protective film formed during sliding processes contributes to the increase in wear resistance.     

Time‐lapse lab‐based x‐ray nano‐CT study of corrosion damage

An experimental protocol (workflow) has been developed for time‐lapse x‐ray nanotomography (nano‐CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano‐CT with the use of a combination of x‐ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time. For the pigmented polymer coating containing nominally strontium aluminium polyphosphate, the strontium‐rich components within the materials are observed to leach extensively whereas the aluminium‐rich components are more resistant to dissolution. In the case of AA2099 it is found that the initial grain boundary corrosion is driven by the presence of copper‐rich phases and is then followed by the corrosion of grains of specific orientation.     

Finite‐element heat‐transfer analysis of a PEEK‐steel sliding pair in a pin‐on‐disc configuration

Finite‐element (FE) thermal models have been developed in order to study the temperature distribution in a sliding pair comprising a poly(ether ether ketone) (PEEK) pin and a steel disc in a pin‐on‐disc configuration. First, a moving heat source model for the disc was created. An alternative distributed heat source model was also produced in order to reduce computing time for the evaluation of the moving heat source model by some orders of magnitude. This latter model gave the same results as the moving heat source model, except for a small region just below the moving heat source. On the basis of the distributed heat source approach, a complete axisymmetric FE model for the disc side (taking the effect of thermal resistance between the assembled components into consideration) and a steady‐state quarter model for the pin were developed. Water cooling and air cooling of the steel shaft were also compared. It was found that air cooling allowed a higher temperature in the contact region of the two sliding partners. The experimental results obtained with thermocouples and a thermal camera showed good agreement with the model predictions.     

Real‐space observation of strong metal‐support interaction: state‐of‐the‐art and what's the next

The real‐space resolving of the encapsulated overlayer in the well‐known model and industry catalysts, ascribed to the advent of dedicated transmission electron microscopy, enables us to probe novel nano/micro architecture chemistry for better application, revisiting our understanding of this key issue in heterogeneous catalysis. In this review, we summarize the latest progress of real‐space observation of SMSI in several well‐known systems mainly covered from the metal catalysts (mostly Pt) supported by the TiO₂, CeO₂ and Fe₃O₄. As a comparison with the model catalyst Pt/Fe₃O₄, the industrial catalyst Cu/ZnO is also listed, followed with the suggested ongoing directions in the field.     

A simple,straightforward correlative live‐cell‐imaging‐structured‐illumination‐microscopy approach for studying organelle dynamics

Most cellular organelles are highly dynamic and continuously undergo membrane fission and fusion to mediate their function. Documenting organelle dynamics under physiological conditions, therefore, requires high temporal resolution of the recording system. Concurrently, these structures are relatively small and determining their substructural organization is often impossible using conventional microscopy. Structured Illumination Microscopy (SIM) is a super resolution technique providing a two‐fold increase in resolution. Importantly, SIM is versatile because it allows the use of any fluorescent dye or protein and, hence, is highly applicable for cell biology. However, similar to other SR techniques, the applicability of SIM to high‐speed live cell imaging is limited. Here we present an easy, straightforward methodology for coupling of high‐speed live cell recordings, using spinning disk (SD) microscopy, with SIM. Using this simple methodology, we are able to track individual mitochondrial membrane fission and fusion events in real time and to determine the network connectivity and substructural organization of the membrane at high resolution. Applying this methodology to other cellular organelles such as, ER, golgi, and cilia will no doubt contribute to our understanding of membrane dynamics in cells. Microsc. Res. Tech. 78:777–783, 2015. © 2015 Wiley Periodicals, Inc.     

Three‐dimensional imaging of whole mouse models: comparing nondestructive X‐ray phase‐contrast micro‐CT with cryotome‐based planar epi‐illumination imaging

In this study, we compare two evolving techniques for obtaining high‐resolution 3D anatomical data of a mouse specimen. On the one hand, we investigate cryotome‐based planar epi‐illumination imaging (cryo‐imaging). On the other hand, we examine X‐ray phase‐contrast micro‐computed tomography (micro‐CT) using synchrotron radiation. Cryo‐imaging is a technique in which an electron multiplying charge coupled camera takes images of a cryo‐frozen specimen during the sectioning process. Subsequent image alignment and virtual stacking result in volumetric data. X‐ray phase‐contrast imaging is based on the minute refraction of X‐rays inside the specimen and features higher soft‐tissue contrast than conventional, attenuation‐based micro‐CT. To explore the potential of both techniques for studying whole mouse disease models, one mouse specimen was imaged using both techniques. Obtained data are compared visually and quantitatively, specifically with regard to the visibility of fine anatomical details. Internal structure of the mouse specimen is visible in great detail with both techniques and the study shows in particular that soft‐tissue contrast is strongly enhanced in the X‐ray phase images compared to the attenuation‐based images. This identifies phase‐contrast micro‐CT as a powerful tool for the study of small animal disease models.     

Cryo‐scanning x‐ray diffraction microscopy of frozen‐hydrated yeast

We developed cryo‐scanning x‐ray diffraction microscopy, utilizing hard x‐ray ptychography at cryogenic temperature, for the noninvasive, high‐resolution imaging of wet, extended biological samples and report its first frozen‐hydrated imaging. Utilizing phase contrast at hard x‐rays, cryo‐scanning x‐ray diffraction microscopy provides the penetration power suitable for thick samples while retaining sensitivity to minute density changes within unstained samples. It is dose‐efficient and further minimizes radiation damage by keeping the wet samples at cryogenic temperature. We demonstrate these capabilities in two dimensions by imaging unstained frozen‐hydrated budding yeast cells, achieving a spatial resolution of 85 nm with a phase sensitivity of 0.0053 radians. The current work presents the feasibility of cryo‐scanning x‐ray diffraction microscopy for quantitative, high‐resolution imaging of unmodified biological samples extending to tens of micrometres.     

Matrices pattern using FIB; ‘Out‐of‐the‐box’ way of thinking

Focused ion beam (FIB) is an extremely valuable tool in nanopatterning and nanofabrication for potentially high‐resolution patterning, especially when refers to He ion beam microscopy. The work presented here demonstrates an ‘out‐of‐the‐box’ method of writing using FIB, which enables creating very large matrices, up to the beam‐shift limitation, in short times and with high accuracy unachievable by any other writing technique. The new method allows combining different shapes in nanometric dimensions and high resolutions for wide ranges.     

Laser‐preparation of geometrically optimised samples for X‐ray nano‐CT

A robust and versatile sample preparation technique for the fabrication of cylindrical pillars for imaging by X‐ray nano‐computed tomography (nano‐CT) is presented. The procedure employs simple, cost‐effective laser micro‐machining coupled with focused‐ion beam (FIB) milling, when required, to yield mechanically robust samples at the micrometre length‐scale to match the field‐of‐view (FOV) for nano‐CT imaging. A variety of energy and geological materials are exhibited as case studies, demonstrating the procedure can be applied to a variety of materials to provide geometrically optimised samples whose size and shape are tailored to the attenuation coefficients of the constituent phases. The procedure can be implemented for the bespoke preparation of pillars for both lab‐ and synchrotron‐based X‐ray nano‐CT investigations of a wide range of samples.     

An analysis of axial deflection of double‐decker high‐precision bearings vis‐à‐vis conventional ball bearings

Axial deflection of double‐decker high‐precision bearings (DDHPBs) under the influence of axial loads has been theoretically analyzed and has been compared with conventional angular contact and deep‐groove ball bearings of the same bore and outer diameter. The analysis, in general, indicates that the ratio of the axial deflection of DDHPBs to that of the conventional angular contact and deep‐groove ball bearings under the influence of identical axial loads is less than unity. The analysis also indicates that angular contact ball bearings mounted back to back for taking the axial load from both directions can be replaced by DDHPBs, which have less axial deflection and longer life under identical applied loads than angular contact and deep‐groove ball bearings. The better dynamic response characteristics, energy efficiency, uniform stress distribution, lower indentation and deflection on the elements of DDHPBs indicate that DDHPBs have relatively better performance characteristics, higher fatigue life and may have higher potential in various industrial applications as compared to that of the conventional bearings under identical operating conditions. Copyright © 2006 John Wiley & Sons, Ltd.     

FE‐SEM observation of swelled seaweed using hydrophilic ionic liquid; 1‐butyl‐3‐methylimidazolium tetrafluoroborate

The method to observe the exact morphology of swelled seaweed as an example of biological material by field emission scanning electron microscopy (FE‐SEM) with the aid of hydrophilic ionic liquid (IL); 1‐butyl‐3‐methylimidazolium tetrafluoroborate is reported. Seaweed was first swelled in 3.5% NaCl solution and then treated with the IL and water mixture in 1:7 weight ratios and centrifuged to remove the excess IL solution. Thus treated seaweed maintained its morphology even at high magnification and did not show drying in the FE‐SEM chamber. This observation technique might be useful for various kinds of biological materials to be observed under FE‐SEM. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

Two‐In‐one sample preparation for plan‐VIew TEM

Transmission electron microscopy (TEM) sample preparation requires special skills, it is time consuming and costly, hence, an increase of the efficiency is of primary importance. This article describes a method that duplicates the yield of the conventional mechanical and ion beam preparation of plan‐view TEM samples. As a modification of the usual procedures, instead of one two different samples are comprised in a single specimen. The two pre‐cut slabs, one from each samples, are embedded side by side in the window of a 3 mm dia Ti disk and the specimen is thinned mechanically and by ion milling until perforation that occurs at the interface of the two different slabs. That, with proper implementation, provides acceptable size thin area for the TEM study of both samples. The suitability of the two‐in‐one method has been confirmed through examples. Microsc. Res. Tech. 78:599–602, 2015. © 2015 Wiley Periodicals, Inc.     

Chromatographic and non‐chromatographic characterization of poly‐α‐olefins

Both chromatographic and non‐chromatographic techniques were used in the characterization and identification of poly‐α‐olefins. Synthetic base oils, although produced from the same raw material, exhibit different physico‐chemical properties. Their mutual miscibility and behaviour in final engine oils may be predicted from data collected through classical physico‐chemical analysis, simulated distillation chromatography as well as inverse gas chromatography. Copyright © 2007 John Wiley & Sons, Ltd.     

Diesel‐lubricated ta‐C coatings

Samples coated with tetrahedral amorphous carbon were investigated in two different oscillating test setups regarding their friction and wear properties. As lubricants petrodiesel, rapeseed methyl ester biodiesel and a mixture thereof were used. Compared with a petrodiesel‐lubricated uncoated system, friction was reduced for more than 50% when a tetrahedral amorphous carbon coating was applied and biodiesel added to the lubricant. Impurities of monoglycerides are assumed to be the cause for the friction‐modifying effect. Copyright © 2013 John Wiley & Sons, Ltd.     

Investigation of the Thermal Behaviour of Non‐metallic Curved‐Face‐Width Spur Gears

This paper describes a curved‐face‐width spur gear, specially designed for manufacture from non‐metallic materials. The benefits of this gear are the higher contact ratio, bending and Hertzian contact resistance, and greater tooth stiffness compared to standard spur gears. A modified geometry is proposed for the gear tooth, the height of which varies along the gear face width. Due to the reduction in tooth height, in sections away from the gear centre, lower sliding friction is expected, with consequences for the gear's thermal behaviour. The complex gear geometry makes the design of a die difficult; therefore the gears were cut on a milling machine, using a special kinematic generation process and related equipment. The tooth flank profile, an involute or near involute in sections away from the gear half‐width plane, as well as the flank surface quality determined by the single‐cutter tool used for gear manufacture, influence the meshing condition, and can be detrimental to the thermal behaviour of the gear. Experimental tests were carried out to examine the influence of load and speed on the temperature of the curved‐face‐width spur gears with modified geometry. The measured temperature of the non‐standard gear is further compared with the predicted temperature of plastic standard spur gears of the same specification.     

MRT Letter: Two‐photon excitation‐based 2pi Light‐sheet system for nano‐lithography

We propose two‐photon excitation‐based light‐sheet technique for nano‐lithography. The system consists of 2 ‐configured cylindrical lens system with a common geometrical focus. Upon superposition, the phase‐matched counter‐propagating light‐sheets result in the generation of identical and equi spaced nano‐bump pattern. Study shows a feature size of as small as few tens of nanometers with a inter‐bump distance of few hundred nanometers. This technique overcomes some of the limitations of existing nano‐lithography techniques, thereby, may pave the way for mass‐production of nano‐structures. Potential applications can also be found in optical microscopy, plasmonics, and nano‐electronics. Microsc. Res. Tech. 78:1–7, 2015. © 2014 Wiley Periodicals, Inc.     

Registration of phase‐contrast images in propagation‐based X‐ray phase tomography

X‐ray phase tomography aims at reconstructing the 3D electron density distribution of an object. It offers enhanced sensitivity compared to attenuation‐based X‐ray absorption tomography. In propagation‐based methods, phase contrast is achieved by letting the beam propagate after interaction with the object. The phase shift is then retrieved at each projection angle, and subsequently used in tomographic reconstruction to obtain the refractive index decrement distribution, which is proportional to the electron density. Accurate phase retrieval is achieved by combining images at different propagation distances. For reconstructions of good quality, the phase‐contrast images recorded at different distances need to be accurately aligned. In this work, we characterise the artefacts related to misalignment of the phase‐contrast images, and investigate the use of different registration algorithms for aligning in‐line phase‐contrast images. The characterisation of artefacts is done by a simulation study and comparison with experimental data. Loss in resolution due to vibrations is found to be comparable to attenuation‐based computed tomography. Further, it is shown that registration of phase‐contrast images is nontrivial due to the difference in contrast between the different images, and the often periodical artefacts present in the phase‐contrast images if multilayer X‐ray optics are used. To address this, we compared two registration algorithms for aligning phase‐contrast images acquired by magnified X‐ray nanotomography: one based on cross‐correlation and one based on mutual information. We found that the mutual information‐based registration algorithm was more robust than a correlation‐based method.     

An overview of state‐of‐the‐art image restoration in electron microscopy

In Life Science research, electron microscopy (EM) is an essential tool for morphological analysis at the subcellular level as it allows for visualization at nanometer resolution. However, electron micrographs contain image degradations such as noise and blur caused by electromagnetic interference, electron counting errors, magnetic lens imperfections, electron diffraction, etc. These imperfections in raw image quality are inevitable and hamper subsequent image analysis and visualization. In an effort to mitigate these artefacts, many electron microscopy image restoration algorithms have been proposed in the last years. Most of these methods rely on generic assumptions on the image or degradations and are therefore outperformed by advanced methods that are based on more accurate models. Ideally, a method will accurately model the specific degradations that fit the physical acquisition settings. In this overview paper, we discuss different electron microscopy image degradation solutions and demonstrate that dedicated artefact regularisation results in higher quality restoration and is applicable through recently developed probabilistic methods.     

Viscometric studies of oil‐in‐water mixtures

An interesting property of oil‐in‐water (o/w) mixtures that has attracted the attention of tribologists, is their ability to form thicker hydrodynamic films than those expected from their apparent rheological properties. In concentrated contacts lubricated with o/w mixtures the oil phase is believed to separate out on the metal surface. To study this phenomenon, experiments have been conducted on a specially designed viscometer rig, with different concentrations of o/w mixtures used as a lubricant. The rig was composed of a metal tube with a straight and parallel cylindrically ground bore and metal ‘droppers’ of similar tolerances. The droppers can descend in the tube filled with the o/w mixture at a uniform velocity; the radial clearances between the descending droppers and the tube are very small. It was found that, even at oil concentrations as low as a few per cent, higher viscosity values for o/w mixtures are obtained in concentrated contacts, in relation to their bulk values. These results can be quantitatively explained in a theory which assumes trapping of oil particles between metal surfaces, correlated to the displacement energy at the oil—water—metal boundaries.