Sol-gel-derived TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> implant coatings for direct tissue attachment. Part I: design,preparation and characterization

A series of sol-gel derived TiO₂–SiO₂ mixed oxide coatings were prepared by carefully controlling the process parameters to obtain silica-releasing coatings consisting of nanoparticles. These features are of paramount importance for enhanced cell adhesion and activation. To achieve both these goals the Ti-alkoxide and Si-alkoxide were first separately hydrolysed and the titania–silica mixed sol was further reacted before the dipping process to obtain the desired particle sizes resulting to the biologically favourable topographical features. Silica release was observed from all the prepared coatings and it was dependent on SiO₂ amount added to the sols, i.e., the higher the added amount the higher the release. In addition, calcium phosphate was able to nucleate on the coatings. From the obtained SiO₂ dissolution data, together with the detailed XPS peak analysis, the mixed oxide coatings are concluded to be chemically heterogeneous, consisting of TiO₂ and SiO₂ species most likely linked together by Ti–O–Si bonds. TiO₂ is chemically stable making long-term implant coating possible and the desired nanoscale dimensions were well preserved although the composition was changed as a consequence of SiO₂ dissolution under in vitro conditions.     

Prediction of the spatial resolution of magnetic particle imaging using the modulation transfer function of the imaging process

The magnetic particle imaging method allows for the quantitative determination of spatial distributions of superparamagnetic nanoparticles in vivo. Recently, it was shown that the 1-D magnetic particle imaging process can be formulated as a convolution. Analyzing the width of the convolution kernel allows for predicting the spatial resolution of the method. However, this measure does not take into account the noise of the measured data. Furthermore, it does not consider a reconstruction step, which can increase the resolution beyond the width of the convolution kernel. In this paper, the spatial resolution of magnetic particle imaging is investigated by analyzing the modulation transfer function of the imaging process. An expression for the spatial resolution is derived, which includes the noise level and which is validated in simulations and experiments.     

Enhanced performance of printed organic diodes using a thin interfacial barrier layer

Printed, organic diodes with a thin organic interfacial layer forming a Schottky barrier were fabricated and characterized. Experiments indicated that the thickness of the barrier layer is <10 nm. The interfacial layer reduces the reverse current of the diode by 2 orders of magnitude without significantly affecting the forward characteristics above 1 V. As a result, printed organic diodes with a rectification ratio of 5 orders of magnitude were fabricated. The diodes enable applications where low reverse currents are needed.     

One‐Step C‐Terminal Deprotection and Activation of Peptides with Peptide Amidase from Stenotrophomonas maltophilia in Neat Organic Solvent

Chemoenzymatic peptide synthesis is a rapidly developing technology for cost effective peptide production on a large scale. As an alternative to the traditional C→N strategy, which employs expensive N‐protected building blocks in each step, we have investigated an N→C extension route that is based on activation of a peptide C‐terminal amide protecting group to the corresponding methyl ester. We found that this conversion is efficiently catalysed by Stenotrophomonas maltophilia peptide amidase in neat organic media. The system excludes the possibility of internal peptide cleavage as the enzyme lacks intrinsic protease activity. The produced peptide methyl ester was used for peptide chain extension in a kinetically controlled reaction by a thermostable protease.

     

Atmospheric-pressure plasma treatment of polyamide 6 composites for bonding with polyurethane

An atmospheric-pressure plasma jet (APPJ)-based surface treatment process was investigated for the structural (τ_B > 15 MPa) adhesive bonding of polyamide 6 (PA6) composites. The treated surfaces were examined by contact angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM). Additionally, the shear strengths of single lap specimens were determined as a function of different plasma intensities and polyurethane adhesives. Our results show that APPJ leads to an increase of the surface free energy, oxygen concentration, and number of functional groups. Furthermore, the topography of the surface was significantly modified by exposure to APPJ. AFM measurements show that special attention has to be paid to the intensity of the plasma treatment to avoid melting and flattening of the PA6 surface on the nanometer scale. With optimized multiple APPJ treatments, lap shear strength of 20 MPa was achieved for the first time for this material system, allowing the material system to be employed in future automobile applications.     

Effects of wood flour modification on the fire retardancy of wood–plastic composites

Wood–plastic composites (WPC) are materials that combine the properties of wood and plastics. Both are flammable organic materials. Fire safety is considered to be an important issue especially in construction applications. In this research, the fire safety of WPC material is improved by using modification chemicals for wood flour treatment. The effectiveness of the modification is studied with a cone calorimeter device. Mechanical properties and water absorption are also examined. Scanning electron microscopy is used for analyzing the interfacial adhesion of the fiber and matrix. The results show that the fire performance of WPC material can be enhanced through wood modification, which can also improve the moisture uptake performance and the interfacial adhesion of the material. However the mechanical properties decrease as a result of modification with the used fire retardants.     

Monitoring androstenone levels in boars by direct immunochemical analysis of serum samples

The possibility of using blood samples for screening high levels of boar taint steroid androstenone (5α-androst-16-en-3-one) was studied both in living animals at the farm and carcasses at the slaughterhouse. The steroid was measured from boar serum and fat samples with a simple time-resolved fluoroimmunoassay. Fat samples contained androstenone in the range of 90-7500 ng/g (n=214), and 74.8% of the samples exhibited fat androstenone levels above 500 ng/g. Androstenone concentrations in blood samples were measured by direct serum assay and ranged up to 215 ng/ml (n=214). The levels of androstenone were correlated (r=0.78-0.88, P<0.001) between the serum and fat samples obtained at slaughter and serum samples taken at the farm 7-11 days before slaughter. A direct serum analysis seems to give a reliable indication of the androstenone level in fat and it can also be used in the screening of living animals.     

An evaluation of pure spectrum-based fault localization techniques for large-scale software systems

Pure spectrum-based fault localization (SBFL) is a well-studied statistical debugging technique that only takes a set of test cases (some failing and some passing) and their code coverage as input and produces a ranked list of suspicious program elements to help the developer identify the location of a bug that causes a failed test case. Studies show that pure SBFL techniques produce good ranked lists for small programs. However, our previous study based on the iBugs benchmark that uses the Aspect J repository shows that, for realistic programs, the accuracy of the ranked list is not suitable for human developers. In this paper, we confirm this based on a combined empirical evaluation with the iBugs and the Defects4 J benchmark. Our experiments show that, on average, at most ∼40%, ∼80%, and ∼90% of the bugs can be localized reliably within the first 10, 100, and 1000 ranked lines, respectively, in the Defects4 J benchmark. To reliably localize 90% of the bugs with the best performing SBFL metric D^∗, ∼450 lines have to be inspected by the developer. For human developers, this remains unsuitable, although the results improve compared with the results for the Aspect J benchmark. Based on this study, we can clearly see the need to go beyond pure SBFL and take other information, such as information from the bug report or from version history of the code lines, into consideration.     

Potential-induced lifting of the Au(1 0 0)-surface reconstruction studied with DFT

The potential-induced surface reconstruction of Au(1 0 0) was studied by a combination of density functional theory (DFT) and thermodynamic considerations. On the basis of realistic models for the reconstructed surface ((5 × 1) and (7 × 1) unitcells), in which a hexagonal overlayer was located above the bulk-truncated Au(1 0 0) surface, we found that applying an electric field causes a slight lifting of the overlayer, leading to a stronger surface buckling than without electric field. Using experimental cyclovoltammetry measurements we were able to relate the electric field applied in our calculations to the electrode potential. The resulting surface free energy curves showed a transition from the hexagonal-reconstructed surface phase to the non-reconstructed structure between +0.5 and +0.6 V (versus SCE-electrode) depending on the ion concentration in the electrolyte. Higher potentials values are required at lower electrolyte concentrations.