The effects of handling and storage on magnesium based implants — First results

The present work aimed to investigate the influence of acetone and formalin as well as the duration and type of storage on magnesium based implants by means of microscopic, μ-computed tomographic, scanning electron microscopic, EDX and metallographic investigations.In contrast to storing in acetone, storage in formalin led to an increase in surface to volume ratio, and a decrease of the volume and the density. The various types of storage exerted no differing effects on the implants but with increasing storage duration, a spreading of oxygen rich areas on the surface, increased precipitations and a decrease in grain size could be observed.     

Proteomic serum biomarkers and their potential application in cancer screening programs

Early diagnosis of cancer is of pivotal importance to reduce disease-related mortality. There is great need for non-invasive screening methods, yet current screening protocols have limited sensitivity and specificity. The use of serum biomarkers to discriminate cancer patients from healthy persons might be a tool to improve screening programs. Mass spectrometry based proteomics is widely applied as a technology for mapping and identifying peptides and proteins in body fluids. One commonly used approach in proteomics is peptide and protein profiling. Here, we present an overview of profiling methods that have the potential for implementation in a clinical setting and in national screening programs.     

Viscoelastic properties of mineralized alginate hydrogel beads

Alginate hydrogels have applications in biomedicine, ranging from delivery of cells and growth factors to wound management aids. However, they are mechanically soft and have shown little potential for the use in bone tissue engineering. Here, the viscoelastic properties of alginate hydrogel beads mineralized with calcium phosphate, both by a counter-diffusion (CD) and an enzymatic approach, are characterized by a micro-manipulation technique and mathematical modeling. Fabricated hydrogel materials have low mineral content (below 3?% of the total hydrogel mass, which corresponds to mineral content of up to 60?% of the dry mass) and low dry mass content (<5?%). For all samples compression and hold (relaxation after compression) data was collected and analyzed. The apparent Young's modulus of the mineralized beads was estimated by the Hertz model (compression data) and was shown to increase up to threefold upon mineralization. The enzymatically mineralized beads showed higher apparent Young's modulus compared to the ones mineralized by CD, even though the mineral content of the former was lower. Full compression-relaxation force-time profiles were analyzed using viscoelastic model. From this analysis, infinite and instantaneous Young's moduli were determined. Similarly, enzymatic mineralized beads, showed higher instantaneous and infinite Young's modulus, even if the degree of mineralization is lower then that achieved for CD method. This leads to the conclusion that both the degree of mineralization and the spatial distribution of mineral are important for the mechanical performance of the composite beads, which is in analogy to highly structured mineralized tissues found in many organisms.     

Parameter ranking by orthogonalization—Applied to nonlinear mechanistic models

The paper addresses methods for parameter sensitivity analysis in a large, nonlinear, mechanistic model which is to be run in an on-line estimation scheme. The parameter sensitivity has been obtained by numeric approximation. The paper proposes and applies successive orthogonalization of the sensitivity derivative for parameter ranking. The method is easy to implement and the results are easily interpreted. Orthogonalization of the sensitivity matrix gives a triangular form of the squared sensitivity. The paper shows how the triangular form of the sensitivity derivative gives a particularly easy form of the variance contribution of individual parameters, provided the model error can be assumed Gaussian. This information has been used to decide how many parameters from the ranked set are to be selected for on-line estimation.     

Release and characterization of single side chains of white cabbage pectin and their complement‐fixing activity

A mixture of single side chains from white cabbage pectin were obtained by anion exchange chromatography after applying mild chemical conditions promoting β‐elimination. These pectin fragments were characterized by their molecular weight distribution, sugar composition, ¹³C‐NMR, and MALDI‐TOF‐MS analysis. These analyses revealed that the large oligosaccharides released by β‐eliminative treatment were composed of α‐1,5 linked arabinosyl residues with 2‐ and 3‐linked α‐arabinosyl side chains, and, or β‐1,4 linked galactosyl side chains. Fractions were tested for complement‐fixing activity in order to determine their interaction with the complement system. These results strongly indicated that there was a minimal unit size responsible for the complement‐fixing activity. Neutral pectin fragments (?8 kDa) obtained from β‐elimination were inactive in the complement system, although they contained a sugar composition previously shown to be highly active. Larger pectin fragments (?17 kDa) retained some activity, but much lower than polymers containing rhamnogalacturonan type 1 (RGI) structures isolated from the same source. This implied that structural elements containing multiple side chains is necessary for efficient complement‐fixing activity.     

Emissions of soot,PAHs, ultrafine particles,NOx, and other health relevant compounds from stressed burning of candles in indoor air

Burning candles release a variety of pollutants to indoor air, some of which are of concern for human health. We studied emissions of particles and gases from the stressed burning of five types of pillar candles with different wax and wick compositions. The stressed burning was introduced by controlled fluctuating air velocities in a 21.6 m³ laboratory chamber. The aerosol physicochemical properties were measured both in well-mixed chamber air and directly above the candle flame with online and offline techniques. All candles showed different emission profiles over time with high repeatability among replicates. The particle mass emissions from stressed burning for all candle types were dominated by soot (black carbon; BC). The wax and wick composition strongly influenced emissions of BC, PM_2.5, and particle-phase polycyclic aromatic hydrocarbons (PAHs), and to lower degree ultrafine particles, inorganic and organic carbon fraction of PM, but did not influence NO_x, formaldehyde, and gas-phase PAHs. Measurements directly above the flame showed empirical evidence of short-lived strong emission peaks of soot particles. The results show the importance of including the entire burn time of candles in exposure assessments, as their emissions can vary strongly over time. Preventing stressed burning of candles can reduce exposure to pollutants in indoor air.