Nanotribological and nanomechanical properties of plasma-polymerized polyterpenol thin films

Organic plasma polymers are currently attracting significant interest for their potential in the areas of flexible optoelectronics and biotechnology. Thin films of plasma-polymerized polyterpenol fabricated under varied deposition conditions were studied using nanoindentation and nanoscratch analyses. Coatings fabricated at higher deposition power were characterized by improved hardness, from 0.33 GPa for 10 W to 0.51 GPa for 100 W at 500-μN load, and enhanced wear resistance. The elastic recovery was estimated to be between 0.1 and 0.14. Coatings deposited at higher RF powers also showed less mechanical deformation and improved quality of adhesion. The average (R a) and root mean square (R q) surface roughness parameters decreased, from 0.44 nm and 0.56 nm for 10 W to 0.33 nm and 0.42 nm for 100 W, respectively.

Plasma polymerisation and retention of antibacterial properties of terpinen-4-ol

Plasma polymerisation was used to deposit thin oligomeric films of terpinen-4-ol on a range of substrates. The coatings were examined in terms of their chemical properties and surface architecture to ascertain the changes in chemical composition as a result of exposure to the plasma field. The antifouling and antimicrobial activity of oligomeric terpinen-4-ol coatings were then examined against such human pathogens as Staphylococcus aureus, Pseudomonas aeruginosa and Staphylococcus epidermis. The bacterial adhesion patterns were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM).

Effect of iodine doping on surface and optical properties of polyterpenol thin films

This study presents the effect of iodine doping on optical and surface properties of polyterpenol thin films deposited from non-synthetic precursor by means of plasma polymerisation. Spectroscopic ellipsometry studies showed iodine doping reduced the optical band gap from 2.82 eV to 1.50 eV for pristine and doped samples respectively. Higher levels of doping notably reduced the transparency of films, an issue if material is considered for applications that require high transparency. Contact angle studies demonstrated higher hydrophilicity for films deposited at increased doping levels, results confirmed by XPS Spectroscopy and FTIR. Doping had no significant effect on the surface profile or roughness of the film.

Structural and thermal properties of inorganic–organic montmorillonite: Implications for their potential environmental applications

Inorganic–organic clays (IOCs), clays intercalated with both organic cations such as cationic surfactants and inorganic cations such as metal hydroxy polycations have the properties of both organic and pillared clays, and thereby the ability to remove both inorganic and organic contaminants from water simultaneously. In this study, IOCs were synthesised using three different methods with different surfactant concentrations. Octadecyltrimethylammonium bromide (ODTMA) and hydroxy aluminium ([Al13O4 (OH)24(H2O)12]7+ or Al13) are used as the organic and inorganic modifiers (intercalation agents). According to the results, the interlayer distance, the surfactant loading amount and the Al/Si ratio of IOCs strictly depend on the intercalation method and the intercalation agent ratio. Interlayers of IOCs synthesised by intercalating ODTMA before Al13 and IOCs synthesised by simultaneous intercalation of ODTMA and Al13 were increased with increasing the ODTMA concentration used in the synthesis procedure and comparatively high loading amounts could be observed in them. In contrast, Al/Si decreased with increasing ODTMA concentration in these two types of IOCs. The results suggest that Al-pillars can be fixed within the interlayers by calcination and any increment in the amount of ODTMA used in the synthesis procedure did not affect the interlayer distance of the IOCs. Overall the study provides valuable insights into the structure and properties of the IOCs and their potential environmental applications.

Small fibre neuropathy in patients with latent autoimmune diabetes in adults

The prevalence of latent autoimmune diabetes in adults (LADA) in patients diagnosed with type 2 diabetes mellitus (T2DM) ranges from 7 to 10% (1). They present at a younger age and have a lower BMI but poorer glycemic control, which may increase the risk of complications (2). However, a recent analysis of the Collaborative Atorvastatin Diabetes Study (CARDS) has demonstrated no difference in macrovascular or microvascular events between patients with LADA and T2DM, but neuropathy was not assessed (3). Previous studies quantifying neuropathy in patients with LADA are limited. In this study, we aimed to accurately quantify neuropathy in subjects with LADA compared with matched patients with T2DM.

Location and scale mixtures of Gaussians with flexible tail behaviour: Properties, inference and application to multivariate clustering

The family of location and scale mixtures of Gaussians has the ability to generate a number of flexible distributional forms. The family nests as particular cases several important asymmetric distributions like the Generalized Hyperbolic distribution. The Generalized Hyperbolic distribution in turn nests many other well known distributions such as the Normal Inverse Gaussian. In a multivariate setting, an extension of the standard location and scale mixture concept is proposed into a so called multiple scaled framework which has the advantage of allowing different tail and skewness behaviours in each dimension with arbitrary correlation between dimensions. Estimation of the parameters is provided via an EM algorithm and extended to cover the case of mixtures of such multiple scaled distributions for application to clustering. Assessments on simulated and real data confirm the gain in degrees of freedom and flexibility in modelling data of varying tail behaviour and directional shape.

Investigation of the effects of extracellular osmotic pressure on morphology and mechanical 1 properties of individual chondrocyte

It has been demonstrated that most cells of the body respond to osmotic pressure in a systematic manner. The disruption of the collagen network in the early stages of osteoarthritis causes an increase in water content of cartilage which leads to a reduction of pericellular osmolality in chondrocytes distributed within the extracellular environment. It is therefore arguable that an insight into the mechanical properties of chondrocytes under varying osmotic pressure would provide a better understanding of chondrocyte mechanotransduction and potentially contribute to knowledge on cartilage degeneration. In this present study, the chondrocyte cells were exposed to solutions with different osmolality. Changes in their dimensions and mechanical properties were measured over time. Atomic Force Microscopy (AFM) was used to apply load at various strain-rates and the force-time curves were logged. The thin-layer elastic model was used to extract the elastic stiffness of chondrocytes at different strain-rates and at different solution osmolality. In addition, the porohyperelastic (PHE) model was used to investigate the strain-rate dependent responses under the loading and osmotic pressure conditions. The results revealed that the hypo-osmotic external environment increased chondrocyte dimensions and reduced Young’s modulus of the cells at all strain-rates tested. In contrast, the hyper-osmotic external environment reduced dimensions and increased Young’s modulus. Moreover, by using the PHE model coupled with inverse FEA simulation, we established that the hydraulic permeability of chondrocytes increased with decreasing extracellular osmolality which is consistent with previous work in the literature. This could be due to a higher intracellular fluid volume fraction with lower osmolality.

Career Adapt-Abilities Scale—Iran Form: Psychometric properties and relationships with career satisfaction and entrepreneurial intentions

This study examined the psychometric properties of a Persian translation of the Career Adapt-Abilities Scale (CAAS—Iran Form) and its relationships with career satisfaction, business opportunity identification, and entrepreneurial intentions. It was hypothesized that career adaptability relates positively to these three outcomes, even when controlling for demographic and employment characteristics. Data were provided by 204 workers from Iran. Results showed that the overall CAAS score and sub-dimension scores (concern, control, curiosity, and confidence) were highly reliable. Moreover, confirmatory factor analyses indicated that the CAAS—Iran Form measures four distinct dimensions that can be combined into a higher-order career adaptability factor. Findings also demonstrated criterion-related validity of the scale with regard to career satisfaction and entrepreneurial intentions. In contrast, overall career adaptability was not significantly related to opportunity identification, while concern related positively, and control related negatively to opportunity identification. Overall, the CAAS—Iran Form has very good psychometric properties and predicts important career outcomes, suggesting that it can be used for career counseling and future research with Persian-speaking workers.

Psychometric properties of the DCDDaily-Q: A new parental questionnaire on children's performance in activities of daily living

Difficulties in the performance of activities of daily living (ADL) are a key feature of developmental coordination disorder (DCD). The DCDDaily-Q was developed to address children's motor performance in a comprehensive range ADL. The aim of this study was to investigate the psychometric properties of this parental questionnaire. Parents of 218 five to eight year-old children (DCD group: N=25; reference group: N=193) completed the research version of the new DCDDaily-Q and the Movement Assessment Battery for Children-2 (MABC2) Checklist and Developmental Coordination Disorder Questionnaire (DCDQ). Children were assessed with the MABC2 and DCDDaily. Item reduction analyses were performed and reliability (internal consistency and factor structure) and concurrent, discriminant, and incremental validity of the DCDDaily-Q were investigated. The final version of the DCDDaily-Q comprises 23 items that cover three underlying factors and shows good internal consistency (Cronbach's α>.80). Moderate correlations were found between the DCDDaily-Q and the other instruments used (p<.001 for the reference group; p>.05 for the DCD group). Discriminant validity of the DCDDaily-Q was good for DCDDaily-Q total scores (p<.001) and all 23 item scores (p<.01), indicating poorer performance in the DCD group. Sensitivity (88%) and specificity (92%) were good. The DCDDaily-Q better predicted DCD than currently used questionnaires (R2=.88). In conclusion, the DCDDaily-Q is a valid and reliable questionnaire to address children's ADL performance.

Development and psychometric properties of the DCDDaily: a new test for clinical assessment of capacity in activities of daily living in children with developmental coordination disorder

Objective To develop the DCDDaily, an instrument for objective and standardized clinical assessment of capacity in activities of daily living (ADL) in children with developmental coordination disorder (DCD), and to investigate its usability, reliability, and validity. Subjects Five to eight-year-old children with and without DCD. Main measures The DCDDaily was developed based on thorough review of the literature and extensive expert involvement. To investigate the usability (assessment time and feasibility), reliability (internal consistency and repeatability), and validity (concurrent and discriminant validity) of the DCDDaily, children were assessed with the DCDDaily and the Movement Assessment Battery for Children-2 Test, and their parents filled in the Movement Assessment Battery for Children-2 Checklist and Developmental Coordination Disorder Questionnaire. Results 459 children were assessed (DCD group, n = 55; normative reference group, n = 404). Assessment was possible within 30 minutes and in any clinical setting. For internal consistency, Cronbach’s α = 0.83. Intraclass correlation = 0.87 for test–retest reliability and 0.89 for inter-rater reliability. Concurrent correlations with Movement Assessment Battery for Children-2 Test and questionnaires were ρ = −0.494, 0.239, and −0.284, p < 0.001. Discriminant validity measures showed significantly worse performance in the DCD group than in the control group (mean (SD) score 33 (5.6) versus 26 (4.3), p < 0.001). The area under curve characteristic = 0.872, sensitivity and specificity were 80%. Conclusions The DCDDaily is a valid and reliable instrument for clinical assessment of capacity in ADL, that is feasible for use in clinical practice.

Recent progress on synthesis, multi-scale structure, and properties of Y-Si-O oxides

Yttrium silicates (Y-Si-O oxides), including Y2Si2O7, Y2SiO5, and Y4·67(SiO4)3O apatite, have attracted wide attentions from material scientists and engineers, because of their extensive polymorphisms and important roles as grain boundary phases in improving the high-temperature mechanical/thermal properties of Si3N4and SiC ceramics. Recent interest in these materials has been renewed by their potential applications as high-temperature structural ceramics, oxidation protective coatings, and environmental barrier coatings (EBCs). The salient properties of Y-Si-O oxides are strongly related to their unique chemical bonds and microstructure features. An in-depth understanding on the synthesis - multi-scale structure-property relationships of the Y-Si-O oxides will shine a light on their performance and potential applications. In this review, recent progress of the synthesis, multi-scale structures, and properties of the Y-Si-O oxides are summarised. First, various methods for the synthesis of Y-Si-O ceramics in the forms of powders, bulks, and thin films/coatings are reviewed. Then, the crystal structures, chemical bonds, and atomic microstructures of the polymorphs in the Y-Si-O system are summarised. The third section focuses on the properties of Y-Si-O oxides, involving the mechanical, thermal, dielectric, and tribological properties, their environmental stability, and their structure-property relationships. The outlook for potential applications of Y-Si-O oxides is also highlighted.

Novel synthesis of superparamagnetic Ni-Co-B nanoparticles and their effect on superconductor properties of MgB2

A new procedure for the preparation of amorphous Ni-Co-B nanoparticles is reported, with a detailed investigation of their morphology by X-ray diffraction and transmission electron microscopy, as well as their magnetic properties. Many factors, such as chemical composition, anisotropy, size and shape of the particles, were controlled through chemical synthesis, resulting in the control of morphological and magnetic properties of the nanoparticles. Controlling pH values with ethylenediamine and using sodium dodecyl sulfate surfactant lowered the size of the nanoparticles to below 10 nm. Such a small structure and chemical disorder in nanocrystalline materials lead to magnetic properties that are different from those in their bulk-sized counterparts. The obtained nanoparticles can be used for different purposes, from pharmaceutical applications to implementations in different materials technology. The focus of this research is the synthesis of Ni-Co-B nanoparticles in a new way and studying the reaction of Ni-Co-B nanoparticles with Mg and B precursors and their effect on MgB2 properties. New nanostructures are formed in the reaction of Ni-Co-B nanoparticles with Mg: Mg2Ni, Co2Mg and possibly Mg2Co.

Preparation of Y2Si2O7/ ZrO2 composites and their composition - Mechanical properties - Tribology relationships

In this work, novel Y2Si2O7/ZrO 2 composites were developed for structural and coating applications by taking advantage of their unique properties, such as good damage tolerance, tunable mechanical properties, and superior wear resistance. The γ-Y 2Si2O7/ZrO2 composites showed improved mechanical properties compared to the γ-Y2Si 2O7 matrix material, that is, the Young's modulus was enhanced from 155 to 188 GPa (121%) and the flexural strength from 135 to 254 MPa (181%); when the amount of ZrO2 was increased from 0 to 50 vol%, the γ-Y2Si2O7/ZrO2 composites also presented relatively high facture toughness (>1.7 MPa·m 1/2), but this exhibited an inverse relationship with the ZrO 2 content. The composition-mechanical property-tribology relationships of the Y2Si2O7/ZrO2 composites were elucidated. The wear resistance of the composites is not only influenced by the applied load, hardness, strength, toughness, and rigidity but also effectively depends on micromechanical stability properties of the microstructures. The easy growth of subcritical microcracks in Y 2Si2O7 grains and at grain boundaries significantly contributes to the macroscopic fracture toughness, but promotes the pull-out of individual grains, thus resulting in a lack of correlation between the wear rate and the macroscopic fracture toughness of the composites.

Electrochemical properties and intermediate-temperature fuel cell performance of dense yttrium-doped barium zirconate with calcium addition

Although BaZr 0.8Y 0.2O 3-δ(BZY) possesses large bulk proton conductivity and excellent chemical stability, its poor sinterability and grain boundaries block proton conduction. In this work, the effect of Ca as a co-dopant and as a sintering aid (as CaO), on the sinterability, proton conductivity, and fuel cell performance of BZY was investigated. The addition of 4 mol% CaO significantly improved the BZY sinterability: BZY pellets with densities of 92.7% and 97.5% with respect to the theoretical density were obtained after sintering at 1500°C and 1600°C, respectively. The improved BZY sinterability by CaO addition resulted also in a large proton conductivity; at 600°C, the total conductivity of BZY-CaO was 2.14 × 10 -3 S/cm, in wet Ar. Anode-supported fuel cells with 25 μm-thick BZY-CaO electrolyte membranes were fabricated by a dual-layer co-firing technique. The peak power density of the fuel cell with a BZY-Ni/BZY-4CaO/BZY-LSCF (La 0.6Sr 0.4Fe 0.8Co 0.2O 3-δ) configuration was 141 mW/cm 2 at 700°C, several times larger than the reported values of BZY electrolyte membrane fuel cells sintered with the addition of CuO or ZnO, demonstrating promising features for practical fuel cell applications.

Sinteractive anodic powders improve densification and electrochemical properties of BaZr0.8Y0.2O3-δ electrolyte films for anode-supported solid oxide fuel cells

The difficult sintering of BaZr0.8Y0.2O 3-δ (BZY20) powders makes the fabrication of anode-supported BZY20 electrolyte films complex. Dense BZY20 membranes were successfully fabricated on anode substrates made of sinteractive NiO-BZY20 powders, prepared by a combustion method. With respect to traditional anode substrates made of powders prepared by mechanical mixing, the anode substrates made of the wet-chemically synthesized composite NiO-BZY20 powders significantly promoted the densification of BZY20 membranes: dense BZY20 films were obtained after co-pressing and co-firing at 1300 °C, a much lower temperature than those usually needed for densifying BZY20 membranes. Improved electrochemical performance was also observed: the supported BZY20 films maintained a high proton conductivity, up to 5.4 × 10-3 S cm-1 at 700 °C. Moreover, an anode-supported fuel cell with a 30 m thick BZY20 electrolyte film fabricated at 1400 °C on the anode made of the wet-chemically synthesized NiO-BZY20 powder showed a peak power density of 172 mW cm-2 at 700 °C, using La0.6Sr0.4Co 0.2Fe0.8O3-δ-BaZr0.7Y 0.2Pr0.1O3-δ as the cathode material, with a remarkable performance for proton-conducting solid oxide fuel cell (SOFC) applications.