A novel cyclic RGD-containing peptide polymer improves serum-free adhesion of adipose tissue-derived mesenchymal stem cells to bone implant surfaces

Seeding of bone implants with mesenchymal stem cells (MSCs) may promote osseointegration and bone regeneration. However, implant material surfaces, such as titanium or bovine bone mineral, fail to support rapid and efficient attachment of MSCs, especially under serum-free conditions that may be desirable when human applications or tightly controlled experiments are envisioned. Here we demonstrate that a branched poly[Lys(Ser_i-DL-Ala_m)] polymer functionalized with cyclic arginyl-glycyl-aspartate, when immobilized by simple adsorption to tissue culture plastic, surgical titanium alloy (Ti6Al4V), or Bio-Oss^® bovine bone substitute, significantly accelerates serum-free adhesion and enhances seeding efficiency of human adipose tissue-derived MSCs. Moreover, when exposed to serum-containing osteogenic medium, MSCs survived and differentiated on the peptide-coated scaffolds. In summary, the presented novel polypeptide conjugate can be conveniently used for coating various surfaces, and may find applications whenever quick and efficient seeding of MSCs is required to various scaffolds in the absence of serum.     

Phase-retrieval analysis of pre- and post-repair Hubble Space Telescope images

Phase-retrieval measurements of point-spread functions from the pre- and post-repair Hubble Space Telescope are presented. The primary goal was to determine the aberrations present in the second wide-field and planetary camera (WFPC2) to align and validate its corrective optics. With both parametric model-fitting techniques and iterative (Gerchberg-Saxton) methods, accurate measurements have been obtained of the WFPC2 and Hubble Space Telescope optics, including improved maps of the zonal errors in the mirrors. Additional phase-retrieval results were obtained for the aberrated, prerepair cameras and the corrected faint-object camera. The information has been used to improve models produced by point-spread-function simulation programs. On the basis of the measurements a conic constant for the primary mirror of κ = -1.0144 has been derived.     

Towards a balanced trade-off between speed and accuracy in unsupervised data-driven image segmentation

When it comes to image segmentation in the megapixel domain, most state-of-the-art algorithms use sampling to reduce the amount of data to be processed to reach a lower running time. Random patterns and equidistant sampling usually result in a suboptimal result because, in general, the distribution of image content is not homogeneous. The segmentation framework we propose in this paper, employs a content-adaptive technique that samples homogeneous and inhomogeneous regions sparsely and densely, respectively, thus it preserves information content in a computationally efficient way. Both the sampling procedure and the pixel-cluster assignment are guided by the same nonlinear confidence value, calculated for each image pixel with no overhead, which describes the strength of the pixel-cluster bond. Building on this confidence scheme, each pixel is associated with the most similar class with respect to its spatial position and color. We compare the performance of our framework to other segmentation algorithms on publicly available segmentation databases and using a set of 10-megapixel images, we show that it provides similar segmentation quality to a mean shift-based reference in an order of magnitude shorter time, the speedup being proportional to the amount of details in the input image. Based on our findings, we also sketch up novel design aspects to be taken into account when designing a high resolution evaluation framework.     

Poly(imide-siloxane) films with controlled thickness

Polyimides containing siloxane moieties are used in some advanced applications. For example, these polymers can be employed as separation membranes in the form of self-standing, thin films. These products are formed by components of different polarities that have the tendency, at least partly, to separate in the final materials, with an impact on their final, bulk, and/or surface properties. The aim of this work is to study the dependence of the composition of the polyimide, poly(imide-siloxane) (PIS) and copolymeric PIS self-standing films differing in thickness on their properties. The important finding is that there is a rather large difference observed in the water contact angle on the film side oriented toward the air atmosphere during film preparation and that oriented toward a hydrophobic Teflon surface. Nevertheless, the gas transport properties of carbon dioxide and methane for these membranes are more influenced by the membrane composition than by the surface properties.     

Corrosion Rates of Stainless Steels in Renewable Biofuel Sources of Refined Rapeseed Oil,Waste Cooking Oil and Animal Waste Lard

Protection of Metals and Physical Chemistry of Surfaces - The 1.4541 and the 1.4571 stainless steels and a carbon steel were subjected to immersion corrosion tests in stagnant and stirred biomass...     

Characterisation of various grape seed oils by volatile compounds,triacylglycerol composition,total phenols and antioxidant capacity

Grape seed oil (Oleum vitis viniferae) representing a promising plant fat, mainly used for culinary and pharmaceutical purposes as well as for various technical applications, was subject of the present investigation. HS-SPME-GC–MS was applied to study volatile compounds in several seed oil samples from different grape oils. The triacylglycerol (TAG) composition of these oils was analyzed by MALDI-TOF-MS/MS. In addition the total phenol content and the antioxidant capacity (using TEAC) of these oils were determined. The headspace of virgin grape oils from white and red grapes was dominated by ethyl octanoate (up to 27.5% related to the total level of volatiles), ethylacetate (up to 25.0%), ethanol (up to 22.7%), acetic acid (up to 17.2%), ethyl hexanoate (up to 17.4%) and 3-methylbutanol (up to 11.0%). Triacylglycerol composition was found to be dominated by LLL (up to 41.8%), LLP (up to 24.3%), LLO (up to 16.3%) and LOO (up to 11.7%), followed by LOP (up to 9.3%) and LOS/OOO (up to 4.3%). Total phenol content ranged between 59 μg/g and 115.5 μg/g GAE. Antioxidant capacity (TEAC) was analyzed to range between 0.09 μg/g and 1.16 μg/g.     

Modelling nitrite in wastewater treatment systems: a discussion of different modelling concepts

Originally presented at the 1st IWA/WEF Wastewater Treatment Modelling Seminar (WWTmod 2008), this contribution has been updated to also include the valuable feedback that was received during the Modelling Seminar. This paper addresses a number of basic issues concerning the modelling of nitrite in key processes involved in biological wastewater water treatment. To this end, we review different model concepts (together with model structures and corresponding parameter sets) proposed for processes such as two-step nitrification/denitrification, anaerobic ammonium oxidation and phosphorus uptake processes. After critically discussing these models with respect to their assumptions and parameter sets, common points of agreement as well as disagreement were elucidated. From this discussion a general picture of the state-of-the-art in the modelling of nitrite is provided. Taking this into account, a number of recommendations are provided to focus further research and development on nitrite modelling in biological wastewater treatment.     

CO tolerant Pt electrocatalysts for PEM fuel cells with enhanced stability against electrocorrosion

An optimized route for preparation of Ti_0.8Mo_0.2O₂–C composite supports for Pt electrocatalysts with 75/25 and 25/75 oxide/carbon mass ratio was elaborated using commercial (BP: Black Pearls 2000) and functionalized (FC) carbon materials. The sol-gel-based synthesis resulted in complete Mo incorporation into the rutile-TiO₂ lattice which is a prerequisite for good CO tolerance and high stability. According to the TG and XPS measurements the highest amount of oxygen-containing functional groups was obtained on the BP carbon annealed in nitrogen at 1000 °C and functionalized with HNO₃ and glucose.The electrochemical stability tests for 500 polarization cycles performed on the 20 wt% Pt/Ti_0.8Mo_0.2O₂–C catalysts revealed similarly small performance loss (8.5–11.8%) in case of all support materials. Considering the negative effect of the oxide content of the catalyst layer on the cell resistance, the catalyst with Ti_0.8Mo_0.2O₂/C = 25/75 ratio was chosen as the most promising.     

Application of magnetic polymethacrylate‐based microspheres for the isolation of DNA from raw vegetables and processed foods of plant origin

A method for the microextraction of DNA from raw vegetables and highly processed foods of plant origin suitable for PCR analysis was developed. It is based on non‐selective binding of DNA in the presence of PEG 6,000/NaCl to hydrophilic magnetic nonporous poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) ‐ P(HEMA‐co‐GMA) microspheres covered by carboxyl groups. The quantitative polymerase chain reaction (qPCR) by in‐house designed primers targeting a highly repetitive rDNA locus allowed for detection of plant DNAs in a wide range of concentrations (0.1 pg/μL to 10 ng/μL). The described procedure is fast and simple. We further demonstrate that relatively mild acidic treatment of vegetable at elevated temperatures resulted in a dramatic reduction of PCR efficiency indicating extensive degradation of DNA during pickling. The described method is suitable for the analysis of highly degraded DNA from pickled food products.

Practical applications

DNA‐based methods, such as the polymerase chain reaction (PCR), represent an important genetic approach for identification of plant species composition of foods. DNA from processed foods varies in both quality and quantity between the protocols used. Plant samples are generally characterised by a complex composition containing various inhibitors of PCR. Current methods have been tailored for specific samples while no universal protocol is available. Development of a simple universal procedure leading to PCR‐ready DNA would be beneficial. Isolation strategies based on solid phase systems have become popular for PCR‐ready DNA isolations from complex matrices. Here we applied magnetic hydrophilic P(HEMA‐co‐GMA) microspheres to extract DNA from raw vegetables and highly processed foods of plant origin. Proposed small scale PCR‐ready DNA extraction protocol was comparable with a silica‐based DNeasy Plant Mini Kit (Qiagen) and classical CTAB extraction methods in quality and amplificability of DNA while it is less costly and time consuming.     

Flash welding and the testing of shafts

Abstract

This paper describes investigations carried out on a manually operated flash welder, including quality control by mechanical and ultrasonic testing.