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Herein, we report the design and synthesis of a series of novel cationic nitrogen‐embedded polyaromatic hydrocarbons with a planar geometry. The synthetic pathway is based on catalytic C−C/C−H bond activation relay that enabled preparation of regioselectively 5,6,10,11‐tetrasubstituted naphtho[2,1,8‐ija]quinolizinium salts bearing various types of substituents. Single‐crystal X‐ray analyses of selected compounds confirmed planarity of the quinolizinium core. Most of the prepared compounds exhibited strong fluorescence (Φs up to >99 %) ranging from 420–600 nm depending on the substitution pattern. According to DFT calculations LUMO is always distributed over the quinolizinium framework regardless of the attached substituents, whereas delocalization of HOMO is related to the substitution pattern. Electrochemical measurements show irreversible reduction of all compounds, which is supported by the calculated location of LUMO orbitals. [ABSTRACT FROM AUTHOR]

Excellent adhesion of electrospun nanofiber (NF) to textile support is crucial for a broad range of their bioapplications, e.g., wound dressing development. We compared the effect of several low- and atmospheric pressure plasma modifications on the adhesion between two parts of composite—polycaprolactone (PCL) nanofibrous mat (functional part) and polypropylene (PP) spunbond fabric (support). The support fabrics were modified before electrospinning by low-pressure plasma oxygen treatment or amine plasma polymer thin film or treated by atmospheric pressure plasma slit jet (PSJ) in argon or argon/nitrogen. The adhesion was evaluated by tensile test and loop test adapted for thin NF mat measurement and the trends obtained by both tests largely agreed. Although all modifications improved the adhesion significantly (at least twice for PSJ treatments), low-pressure oxygen treatment showed to be the most effective as it strengthened adhesion by a factor of six. The adhesion improvement was ascribed to the synergic effect of high treatment homogeneity with the right ratio of surface functional groups and sufficient wettability. The low-pressure modified fabric also stayed long-term hydrophilic (ten months), even though surfaces usually return to a non-wettable state (hydrophobic recovery). In contrast to XPS, highly surface-sensitive water contact angle measurement proved suitable for monitoring subtle surface changes. [ABSTRACT FROM AUTHOR]

Carboxyl coatings are extensively used for adhesion promotion, bio-immobilization and surface reactions thanks to their reactivity towards nucleophilic groups and high wettability. The deposition of relatively stable carboxyl-rich coatings using low-cost atmospheric pressure plasma processes is still challenging. This work is aimed at the investigation of the plasma copolymerization of maleic anhydride (MA) and C 2 H 2 by atmospheric pressure dielectric barrier discharge. The quantification of the carboxyl groups is performed by X-ray photoelectron spectroscopy (XPS) C1s curve fitting and by derivatization with trifluoroethanol. The layer synthesized at optimized monomer flow rate and plasma power contains 5 at.% of carboxyl groups (determined by derivatization combined with XPS) and exhibits the thickness loss below 5% after 128 h in water. The influence of the MA:C 2 H 2 ratio on the layer chemistry, morphology and stability is analyzed. [ABSTRACT FROM AUTHOR]

The human body involves a large number of systems subjected to contact stresses and thus experiencing wear and degradation. The limited efficacy of existing solutions constantly puts a significant financial burden on the healthcare system, more importantly, patients are suffering due to the complications following a partial or total system failure. More effective strategies are highly dependent on the availability of advanced functional materials demonstrating excellent tribological response and good biocompatibility. In this article, we review the recent progress in implementing two-dimensional (2D) materials into bio-applications involving tribological contacts. We further summarize the current challenges for future progress in the field. [Display omitted] • Critical evaluation of the use of 2D materials into bio-(tribological) applications. • 2D materials simultaneously unify good biological and mechanical properties. • They induce an excellent biocompatibility, mechanical strength, and wear resistance. • Derivation of current challenges and future research directions. [ABSTRACT FROM AUTHOR]

Expressions for ellipsometric quantities and reflectance presented are based on a heuristic combination of the Rayleigh–Rice theory and the scalar diffraction theory. The latter takes into account the local slopes and shadowing. The second-order Rayleigh–Rice theory is used to express the local electric field on the rough surface and the obtained expressions are then used in the scalar diffraction theory instead of the expressions corresponding to a smooth surface. A numeric method of evaluation of the quadruple integral resulting from this combination of the two theories is developed, utilising a Gauss-like quadrature. The efficiency of the formulae is illustrated by optical characterisation of rough silicon and gallium arsenide surfaces created using anodic and thermal oxidation, respectively, and covered with native oxide layers. The optical characterisation employs variable-angle spectroscopic ellipsometry and spectroscopic reflectometry. [ABSTRACT FROM AUTHOR]

Synthesis of unsymmetrical [7]-helical compounds possessing the dispiro[2,1- c ]indenofluorene motif was achieved for the first time in good yields. The crucial step of the whole reaction sequence was catalytic intramolecular [2 + 2 + 2] cycloaddition of triynediols by using various transition metal compounds (Co, Ni, etc.). The cyclotrimerizations were accompanied by dehydro-Diels-Alder reaction giving rise to other types of aromatic compounds depending on the respective reaction conditions. Limits of enantioselective cyclotrimerization were assessed. The subsequent transformations of the cyclotrimerization products provided the respective dispiroindenofluorenes. Structures of both unsymmetrical [7]helical cyclotrimerization products as well as three dehydro-Diels-Alder products were unequivocally confirmed by single-crystal X-ray diffraction analyses. Photophysical properties of selected products were determined as well. [Display omitted] • Catalytic [2 + 2 + 2]cyclotrimerization route to unsymmetrical [7]helical indenofluorenes. • Competition of cyclotrimerization with thermal dehydro-Diels-Alder reaction. • Catalytic enantioselective cyclotrimerization. • Photophysical and structural properties of products were determined. [ABSTRACT FROM AUTHOR]

Abstract: Hafnia films prepared onto silicon wafers at three substrate temperatures of 40, 160 and 280°C are optically characterized utilizing the multi-sample method. The characterization uses the combination of variable angle spectroscopic ellipsometry and spectroscopic reflectometry within the spectral region 1.24–6.5eV (190–1000nm). The structural model of the HfO2 films includes boundary nanometric roughness, thickness non-uniformity and refractive index profile. Spectral dependences of the film optical constants are expressed using a recently developed parametrized joint density of states model describing the dielectric response of both interband transitions and excitations of localized states below the band gap. It is shown that the observed weak absorption below the band gap does not correspond to the Urbach tail. [Copyright &y& Elsevier]

Abstract: The optical properties and structure of a-C:H films were modified by addition of nitrogen into the CH4/H2 deposition mixture. Three films prepared in capacitively coupled rf discharge were compared: (a) hydrogenated diamond like carbon film with hydrogen content of 34% and indentation hardness of 21.7GPa, (b) hard a-C:H:N film with nitrogen content of 13% and indentation hardness of 18.5GPa and (c) soft a-C:H:N film with nitrogen content of 10% and indentation hardness of 6.7GPa. It is shown how the parametrized density of states model describing dielectric response of electronic interband transitions can be applied to modified a-C:H:N and how it can be combined with correct treatment of transmittance measured in infrared range using additional Gaussian peaks in joint density of phonon states. This analysis resulted in determination of film dielectric function in wide spectral range (0.045–30eV) and provided also information about the density of states of valence and conduction bands and lattice vibrations. [Copyright &y& Elsevier]

The present paper explores the effect of viscosupplementation on the friction of articular cartilage depending on the rheology of viscosupplements. The experiments were realized on rotational rheometers and a tribometer in pin-on-plate configuration. Five commercially available viscosupplements and their mixtures with synovial fluid were tested. The results showed differences by the order of magnitudes between viscosupplements viscosity and no viscoelastic properties in some of them. The friction was substantially affected by the addition of viscosupplement into the model synovial fluid. In most cases, mixtures of synovial fluid and viscosupplement even showed similar friction as clear viscosupplements. This study is the basis for a better understanding of the short-term changes in articular cartilage frictional behavior after the viscosupplementation of synovial joint. • Rheological analysis of HA-based viscosupplements and their mixtures with synovial fluid. • Frictional behaviour of HA solutions within the model of synovial joint. • Substantial differences in the rheological properties of individual viscosupplements. • No clear dependency between HA viscosity and friction within the contact. • Lubrication regime influenced by HA molecular weight. [ABSTRACT FROM AUTHOR]

Abstract: The combined optical method enabling us to perform the complete optical characterisation of weakly absorbing non-uniform thin films is described. This method is based on the combination of standard variable angle spectroscopic ellipsometry, standard spectroscopic reflectometry at near normal incidence and spectroscopic imaging reflectometry applied at normal incidence. The spectral dependences of the optical constants are determined using the non-imaging methods by using the dispersion model based on parametrisation of the density of electronic states. The local thickness distribution is then determined by imaging reflectometry. The method is illustrated by means of the complete optical characterisation of SiOxCyHz thin films. [Copyright &y& Elsevier]

Hyaluronan (HA) has been recently identified as a key component of the densification of thoracolumbar fascia (TLF), a potential contributor to non-specific lower back pain (LBP) currently treated with manual therapy and systemic or local delivery of anti-inflammatory drugs. The aim of this study was to establish a novel animal model suitable for studying ultrasound-guided intrafascial injection prepared from HA with low and high Mw. Effects of these preparations on the profibrotic switch and mechanical properties of TLF were measured by qPCR and rheology, respectively, while their lubricating properties were evaluated by tribology. Rabbit proved to be a suitable model of TLF physiology due to its manageable size enabling both TLF extraction and in situ intrafascial injection. Surprisingly, the tribology showed that low Mw HA was a better lubricant than the high Mw HA. It was also better suited for intrafascial injection due to its lower injection force and ability to freely spread between TLF layers. No profibrotic effects of either HA preparation in the TLF were observed. The intrafascial application of HA with lower MW into the TLF appears to be a promising way how to increase the gliding of the fascial layers and target the myofascial LBP. • Rabbit is an appropriate model animal for a study of thoracolumbar fascia. • Rabbit thoracolumbar fascia has structure and composition similar to a human fascia. • LMW hyaluronan has better lubricating properties than HMW hyaluronan. • 1 % solution of LMW hyaluronan is injectable into thoracolumbar fascia. [ABSTRACT FROM AUTHOR]

Catalysis, C-C bond cleavage, cyclotrimerization, dispiroindenofluorenes, [9]helical structure Keywords: catalysis; C-C bond cleavage; cyclotrimerization; dispiroindenofluorenes; [9]helical structure EN catalysis C-C bond cleavage cyclotrimerization dispiroindenofluorenes [9]helical structure 1 1 1 10/24/23 20231018 NES 231018 B Direction signs b show a driver which turn to take to reach the desired destination. [Extracted from the article]

The quantitative analysis of the chemistry at the surface of functional plasma polymers is highly important for the optimization of their deposition conditions and, therefore, for their subsequent applications. The chemical derivatization of amine and carboxyl-anhydride layers is a well-known technique already applied by many researchers, notwithstanding the known drawback of the derivatization procedures like side or uncomplete reactions that could lead to “unreliable” results. In this work, X-ray photoelectron spectroscopy (XPS) combined with depth profiling with argon clusters is applied for the first time to study derivatized amine and carboxyl-anhydride plasma polymer layers. It revealed an additional important parameter affecting the derivatization reliability, namely the permeation of the derivatizing molecule through the target analysed layer, i.e. the composite effect of the probe molecule size and the layer porosity. Amine-rich films prepared by RF low pressure plasma polymerization of cyclopropylamine were derivatized with trifluoromethyl benzaldehide (TFBA) and it was observed by that the XPS-determined NH 2 concentration depth profile is rapidly decreasing over top ten nanometers of the layer. The anhydride-rich films prepared by atmospheric plasma co-polymerization of maleic anhydride and C 2 H 2 have been reacted with, parafluoroaniline and trifluoroethyl amine. The decrease of the F signal in top surface layer of the anhydride films derivatized by the “large” parafluoroaniline was observed similarly as for the amine films but the derivatization with the smaller trifluoroethylamine (TFEA) led to a more homogenous depth profile. The data analysis suggests that the size of the derivatizing molecule is the main factor, showing that the very limited permeation of the TFBA molecule can lead to underestimated densities of primary amines if the XPS analysis is solely carried out at a low take-off angle. In contrast, TFEA is found to be an efficient derivatization agent of anhydride groups with high permeability through the carboxyl-anhydride layer. [ABSTRACT FROM AUTHOR]

• Zn-0.8Mg-0.2Sr was successfully extruded in the temperature range 150–300 °C. • Materials extruded at 150 and 200 °C dominated by fine-grained microstructure. • Elongation increased with lower extrusion temperature and higher extrusion ratio. • Various deformation mechanisms dominated under different loading. Zinc-based alloys containing elements well-tolerated by the organism (Mg, Ca, Sr) are considered as perspective biodegradable materials for an application like medical devices such as fixations of fractured bones or even stents. In the presented paper we characterize the relations between microstructure and mechanical properties of extruded Zn-0.8Mg-0.2 Sr alloy (wt%) depending on various parameters like extrusion temperature (150–300 °C) and ratio (11 or 25). Typical analysis including SEM with EBSD and mechanical tests indicate a strong dependence of obtained data on both extrusion temperature and ratio. Relatively wide range of elongation to fracture (2–22%) and anisotropy in compression yield strengths regarding loading direction (50–150 MPa) are explained by the huge effect of grain size, material texture and also the existence of dislocation substructures in materials extruded at elevated temperatures. Based on obtained results, appropriate extrusion conditions (200 °C, extrusion ratio 25) are suggested to reach the combination of superior mechanical properties 244 MPa, 324 MPa and 22% for tensile yield strength, ultimate tensile strength and elongation to fracture, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Main features of GDOES, XPS and ToF-SIMS depth profiling of the thin amine polymer film are compared. • GDOES depth profiling in Ar/O 2 mixture increases etching rate and depth resolution for amine polymer film compared to pure Ar gas. • Etching of polymer surface by glow discharge of Ar/O 2 mixture is based on the synergy of ion sputtering and reactive chemical etching. • GDOES depth profiling is suitable for fast analyses of polymer layers up to a few μm in thickness. Thin polymer films were deposited on polished stainless-steel samples by PECVD from a cyclopropylamine precursor and characterized by X-ray photoelectron spectroscopy, secondary-ion mass spectrometry and glow-discharge optical emission spectroscopy (GDOES) depth profiling. These depth profiles exhibited reasonable agreement. The GDOES involved the erosion of the polymer films in plasma sustained by an asymmetric RF capacitively coupled discharge using both Ar and Ar-O 2 gases. The application of pure Ar caused unwanted effects, such as the broadening of the polymer-film/substrate interface, which were suppressed when using the mixture with oxygen. Another benefit of oxygen was a significant increase in the etching rate by a factor of about 15 as compared to pure argon. The mechanisms involved in the depth profiling using the mixture of gases were elaborated in some detail, taking into account plasma parameters typical for an asymmetric, capacitively coupled RF discharge in a small volume. The main benefit of using the Ar/O 2 GDOES profiling with respect to XPS and SIMS depth profiling is the increased sputtering rate for polymer films. Comparing the GDOES depth profiling with the Ar/O 2 mixture with profiling in pure Ar, the benefits are a higher sputtering rate and better depth resolution at the polymer/substrate interface. [ABSTRACT FROM AUTHOR]

Abstract: In this article we present results of rough surface scattering calculations using a graphical processing unit implementation of the Finite Difference in Time Domain algorithm. Numerical results are compared to real measurements and computational performance is compared to computer processor implementation of the same algorithm. As a basis for computations, atomic force microscope measurements of surface morphology are used. It is shown that the graphical processing unit capabilities can be used to speedup presented computationally demanding algorithms without loss of precision. [Copyright &y& Elsevier]

Total knee replacements are an effective surgical treatment to restore the function of the knee. For an adequate design, knowledge about stresses and lubrication conditions is vital. Part II proposes a fully-coupled transient 3D model for the soft elastohydrodynamically lubricated contact based upon the generalized Reynolds equation and Finite Element Method while Part I of this study focused on experimental observations. Within the scope of this contribution, a numerical model is presented and validated with experimental data. Good agreement between model predictions and experimental data was found. A strong influence of fluid and geometry assumptions and transient effects were found. Besides, it was demonstrated that the rheological synovial fluid properties have a decisive role in the tribological behavior. Image 1 • Combination of experimental investigations with FEM-based numerical modeling. • Good agreement when all relevant influencing factors are considered. • Load and geometry dominated the pressure and film formation in the stance phase. • The swing phase was largely influenced by the kinematics. • The fluid film formation was largely affected by reversal points of motion. [ABSTRACT FROM AUTHOR]

• Plasma polymerization penetration depth into porous media is at least tens of μm. • Deposition rate decreases greatly in wells, the chemistry changes moderately. • Two populations of film-forming species are required to explain the data. • The small sticking probability population allows the large deposition penetration. Understanding the role of substrate geometry is vital for a successful optimization of low-pressure plasma polymerization on non-planar substrates used in bioapplications, such as porous materials or well plates. We investigated the altered transport of film-forming species and properties of the coatings for a cyclopropylamine and argon discharge using a combined analysis of the plasma polymer deposition on flat Si pieces, culture wells, microtrenches, a macrocavity, porous hydroxyapatite scaffolds and electrospun polycaprolactone nanofibrous mats. The aspect ratio of the well structures impacted mainly the deposition rate, whereas the film chemistry was affected only moderately. A large deposition penetration depth into the porous media indicated a relatively low sticking probability of film-forming species. A detailed analysis of microtrench step coverage and macrocavity deposition disproved the model of film-forming species with a single overall sticking probability. At least two populations with two different sticking probabilities were required to fit the experimental data. A majority of the film-forming species (76%) has a large sticking probability of 0.20 ± 0.01 , while still a significant part (24%) has a relatively small sticking probability of 0.0015 ± 0.0002. The presented methodology is widely applicable for understanding the details of plasma-surface interaction and successful applications of plasma polymerization onto complex substrates. [ABSTRACT FROM AUTHOR]

• Quantitative nanoscale magnetic stray field calibration by MFM was implemented. • Transfer function method including deconvolution and regularization was detailed. • Step-by-Step instructions of the calibration procedures were established. • Round robin comparison proves the robustness of the transfer function method. Magnetic force microscopy (MFM) can be considered as a standard tool for nano-scale investigation of magnetic domain structures by probing the local stray magnetic field landscape of the measured sample. However, this generally provides only qualitative data. To quantify the stray magnetic fields, the MFM system must be calibrated. To that end, a transfer function (TF) approach was proposed, that, unlike point probe models, fully considers the finite extent of the MFM tip. However, albeit being comprehensive, the TF approach is not yet well established, mainly due to the ambiguities concerning the input parameters and the measurement procedure. Additionally, the calibration process represents an ill-posed problem which requires a regularization that introduces further parameters. In this paper we propose a guideline for quantitative stray field measurements by standard MFM tools in ambient conditions. All steps of the measurement and calibration procedure are detailed, including reference sample and sample under test (SUT) measurements and the data analysis. The suitability of the reference sample used in the present work for calibrated measurements on a sub-micron scale is discussed. A specific regularization approach based on a Pseudo-Wiener Filter is applied and combined with criteria for the numerical determination of a unique regularization parameter. To demonstrate the robustness of such a defined approach, a round robin comparison of magnetic field measurements was conducted by four laboratories. The guideline, the reference sample and the results of the round robin are discussed. [ABSTRACT FROM AUTHOR]

Observations of superconductivity and charge density waves (CDW) in graphene have been elusive thus far due to weak electron-phonon coupling (EPC) interactions. Here, we report a unique observation of anomalous transport and multiple charge ordering phases at high temperatures (T1∼213K,T2∼325K) in a 0D-2D van der Waals (vdW) heterostructure comprising of single layer graphene (SLG) and functionalized (amine) graphene quantum dots (GQD). The presence of functionalized GQD contributed to charge transfer with shifting of the Dirac point ∼ 0.05 eV above the Fermi level ( ab initio    simulations) and carrier densityn∼-0.3×1012 cm-2confirming p-doping in SLG and two-fold increase in EPC interaction was achieved. Moreover, we elucidate the interplay between electron-electron and electron-phonon interactions to substantiate high temperature EPC driven charge ordering in the heterostructure through analyses of magnetotransport and weak anti-localization (WAL) framework. Our results provide impetus to investigate strongly correlated phenomena such as CDW and superconducting phase transitions in novel graphene based heterostructures., (Creative Commons Attribution license.)

A low-cost Digital Signal Processor (DSP) unit for advanced Scanning Probe Microscopy measurements is presented. It is based on Red Pitaya board and custom built electronic boards with additional high bit depth AD and DA converters. By providing all the necessary information (position and time) with each data point collected it can be used for any scan path, using either existing libraries for scan path generation or creating adaptive scan paths using Lua scripting interface. The DSP is also capable of performing statistical calculations, that can be used for decision making during scan or for the scan path optimisation on the DSP level., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

In this work, we demonstrate the prospect of chemically synthesizing transition metal (Ni) doped magnetic graphene quantum dots (GQDs) with the sole aim of shedding light on their magnetic properties. Our results show that adsorption of nickel hydroxide on predominantly paramagnetic GQDs reveals antiferromagnetic ordering in the M-T profile around 10 K with change of the spin exchange coupling deviating from J = 1/2 to J = 1, mainly arising from the d-p mixing hybridization between the p orbital of carbon from the GQD and the d orbital of Ni. Furthermore, our results are well complemented by ab initio simulations showing asymmetry of the up and down spins around the Fermi level for nickel hydroxide-doped GQDs with long-range spin polarization. Furthermore, the magnitude of the net magnetic moment generated for doped GQDs on the carbon atoms is found to be site-dependent (surface or edge).

Zinc materials are considered promising candidates for bioabsorbable medical devices used for the fixation of broken bones or stents. Materials for these applications must meet high mechanical property requirements. One of the ways to fulfil these demands is related to microstructure refinement, particularly the decrease in grain size. In the present work, we combine two powder metallurgy techniques (mechanical alloying-MA, and spark plasma sintering-SPS) to prepare Zn-1Mg-0.5Sr nanograin material. The microstructure of compacted material consisted of Zn grains and particles of Mg 2 Zn 11 intermetallic phases from 100 to 500 nm in size, which resulted in high values of hardness and a compressive strength equal to 86 HV1 and 327 MPa, respectively. In this relation, the combination of the suggested techniques provides an innovative way to form extremely fine microstructures without significant coarsening during powder compaction at increased temperatures.

Zinc and its alloys are considered as promising materials for the preparation of biodegradable medical devices (stents and bone fixation screws) due to their enhanced biocompatibility. These materials must achieve an ideal combination of mechanical and corrosion properties that can be influenced by alloying or thermomechanical processes. This paper presents the effects of different mechanical alloying (MA) parameters on the composition of Zn-1Mg powder. At the same time, this study describes the influence of preparation by MA on Zn-6Mg and Zn-16Mg alloys. The selected powders were compacted by the spark plasma sintering (SPS) method. Subsequently, their microstructures were studied and their mechanical properties were tested. The overall process led to a significant grain refinement (629 ± 274 nm for Zn-1Mg) and the formation of new intermetallic phases (Mg 2 Zn 11 , MgZn 2 ). The compressive properties of the sintered samples were mainly related to the concentration of the alloying elements, where an increase in concentration led to an improvement in strength but a deterioration in ductility. According to the obtained results, the best properties were obtained for the Zn-1Mg alloy.

The enantioselective synthesis of chiral [7]-helical dispirodihydro[2,1-c]indenofluorenes (DSF-IFs) was achieved for the first time in good yields with high er values (er up to 99 : 1). The crucial step of the whole reaction sequence was the enantioselective intramolecular [2+2+2] cycloaddition of tethered triynediols to indenofluorenediols, which was catalyzed by a Rh/SEGPHOS® complex. Further transformations led to the corresponding DSF-IFs. The prepared helically chiral DSF-IFs combine circularly polarized luminescence (CPL) activity (g lum =∼10 -3 ) with exceptionally high fluorescence quantum yields (up to Φ lum =0.97)., (© 2021 Wiley-VCH GmbH.)

This work presents a general approach for synthesis of substituted [5]-helical dispiroindeno[2,1-c]fluorenes based on Rh-catalyzed intramolecular cyclotrimerization of triynes. This approach was further extended for the first synthesis of configurationally stable [7]-helical dispiroindeno[2,1-c]fluorenes. A series of variously substituted derivatives was prepared and their photophysical and electrochemical properties were evaluated. Their fluorescence emission maxima were in the region of 351-428 nm and quantum yields up to 88 % are the highest measured among the full-carbon helical compounds., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Magnetic force microscopy has unsurpassed capabilities in analysis of nanoscale and microscale magnetic samples and devices. Similar to other Scanning Probe Microscopy techniques, quantitative analysis remains a challenge. Despite large theoretical and practical progress in this area, present methods are seldom used due to their complexity and lack of systematic understanding of related uncertainties and recommended best practice. Use of the Tip Transfer Function (TTF) is a key concept in making Magnetic Force Microscopy measurements quantitative. We present a numerical study of several aspects of TTF reconstruction using multilayer samples with perpendicular magnetisation. We address the choice of numerical approach, impact of non-periodicity and windowing, suitable conventions for data normalisation and units, criteria for choice of regularisation parameter and experimental effects observed in real measurements. We present a simple regularisation parameter selection method based on TTF width and verify this approach via numerical experiments. Examples of TTF estimation are shown on both 2D and 3D experimental datasets. We give recommendations on best practices for robust TTF estimation, including the choice of windowing function, measurement strategy and dealing with experimental error sources. A method for synthetic MFM data generation, suitable for large scale numerical experiments is also presented.

The aim of the present paper is to provide a novel experimental approach enabling to assess the thickness of lubricant film within hip prostheses in meaning of the contribution of particular proteins. Thin film colorimetric interferometry was combined with fluorescent microscopy finding that a combination of optical methods can help to better understand the interfacial lubrication processes in hip replacements. The contact of metal femoral head against a glass disc was investigated under various operating conditions. As a test lubricant, the saline solution containing the albumin and γ-globulin in a concentration 2:1 was employed. Two different mean speeds were applied, 5.7 and 22mm/s, respectively. The measurements were carried out under pure rolling, partial negative and partial positive sliding conditions showing that kinematic conditions substantially affects the formation of protein film. Under pure rolling conditions, an increasing tendency of lubricant film independently on rolling speed was detected, while the total thickness of lubricant film can be attributed mainly to albumin. When the ball was faster than the disc (negative sliding), a very thin lubricant film was observed for lower speed with no significant effect of particular proteins. The increase in sliding speed led to the increase of film thickness mainly caused due to the presence of γ-globulin. On the contrary, when the disc was faster than the ball (positive sliding), the film formation was very complex and time dependent while both of the studied proteins have shown any qualitative change during the test, however the effect of albumin seems to be much more important. Since a very good agreement of the results was obtained, it can be concluded that the approach consisting of two optical methods can provide the fundamental information about the lubricant film formation in meaning of particular proteins while the simultaneous presence of other constituents in model synovial fluid., (Copyright © 2015 Elsevier Ltd. All rights reserved.)