Authenticity control of pine sylvestris essential oil by chiral gas chromatographic analysis of α-pinene

Numerous terpenes present in essential oils (EOs) display one or more chiral centers. Within the same genus the enantiomeric ratio of these compounds can be different. Thus, the determination of enantiomers is a valuable tool to evaluate authenticity and quality of EOs. In here, the terpene profile of primary and commercial pine EOs was analyzed by conventional and chiral gas chromatography coupled to a flame ionization detector. The enantiomeric excess of ( ±)-α-pinene was determined and significant differences between primary and commercially available EOs were observed. Primary EOs of Pinus sylvestris L. showed a positive enantiomeric excess of (+)-α-pinene whereas commercial EOs labeled as P. sylvestris L. exhibited an enantiomeric excess of (−)-α-pinene. Thus, chiral analysis provides useful information on the authenticity of pine EOs and allows to uncover possible mislabeling, the use of the wrong herbal substance and sources of adulteration in pine oil.

Spatio-temporal analysis of glass volume processing using ultrashort laser pulses

Ultrashort laser pulses allow for the in-volume processing of glass through non-linear absorption, resulting in permanent material changes and the generation of internal stress. Across the manifold potential applications of this technology, process optimization requires a detailed understanding of the laser-matter interaction. Of particular relevance are the deposition of energy inside the material and the subsequent relaxation processes. In this paper, we investigate the spatio-temporal evolution of free carriers, energy transfer, and the resulting permanent modifications in the volume of glass during and after exposure to femtosecond and picosecond pulses. For this purpose, we employ time-resolved microscopy in order to obtain shadowgraphic and interferometric images that allow relating the transient distributions to the refractive index change profile. Whereas the plasma generation time is given by the pulse duration, the thermal dynamics occur over several microseconds. Among the most notable features is the emergence of a pressure wave due to the sudden increase of temperature and pressure within the interaction volume. We show how the structure of the modifications, including material disruptions as well as local defects, can be directly influenced by a judicious choice of pulse duration, pulse energy, and focus geometry.

A sulfated cyanobacterial polysaccharide proven as a strong inhibitor of human complement activity in an in vitro assay

Cyanobacterial exopolysaccharides are a rich source of, so far, widely unexplored polysaccharides. One of these exopolysaccharides is a highly sulfated, linear polysaccharide from Synechocystis aquatilis containing the amino sugar N-acetyl-fucosamine. Some sulfated polysaccharides and glycosaminoglycans are known to be inhibitors of the human complement system, which is an important part of the innate immune system. Defects in this system or misregulation can cause serious diseases. Therefore, new compounds with complement inhibiting activity and simple test assays are of great interest. Exopolysaccharides from S. aquatilis (arabinofucans) were compared to those from Synechocystis pevalekii (complex heteropolysaccharides) and the well-known complement inhibitor heparin. Investigations were performed with a modified ELISA test system based on a commercially available test kit quantifying the membrane attack complex. Hereby the testing becomes more stable, robust, reproducible, easier to handle and, for the first time, the effect of exopolysaccharides and heparin on the lectin pathway could be tested. The exopolysaccharides from S. aquatilis could be shown to be a 30 times stronger inhibitor of the classical pathway of the complement system compared to heparin (IC50 = 0.3 µg/mL vs. 9.2 µg/mL). These exopolysaccharides are also inhibitors of the lectin pathway (IC50 = 10.8 µg/mL) in which, however, heparin is more potent (IC50 = 2.0 µg/mL). Interestingly, these exopolysaccharides do not inhibit the alternative pathway. The exopolysaccharides from S. pevalekii are inactive in all pathways. Furthermore, partially hydrolyzed and desulfated exopolysaccharides from S. aquatilis were tested showing that a minimum molecular size and degree of sulfation are important for the inhibitory effects, whereas unspecific influences by complex formation of exopolysaccharides with calcium could be excluded.

Exopolysaccharides of Synechocystis aquatilis are sulfated arabinofucans containing N-acetyl-fucosamine

Cyanobacteria are known to be a rather diverse group of organisms regarding e.g. morphology, metabolism and composition of excreted exopolysaccharides (EPS). Considering the high number of known cyanobacterial species the EPS from only a small percentage are investigated in detail. This work examined EPS from the unicellular strains of Synechocystis aquatilis and S. pevalekii with various methods. The results emphasize the heterogeneity of cyanobacterial EPS. S. pevalekii secrets complex hetero-polysaccharides and acidic proteins as proteoglycan-complexes whereas the protein-free but highly sulfated EPS from S. aquatilis only consist of 4 dominant monosaccharides. Especially remarkable is the composition of these EPS: an arabinofucan with higher amounts of N-acetyl-fucosamine (FucNAc) and only minor quantities of glucose. Both EPS and the newly found component FucNAc in EPS from S. aquatilis extend the possible components of cyanobacterial EPS and the knowledge of heterogeneity of cyanobacterial metabolites.

Large area smoothing of surfaces by ion bombardment: fundamentals and applications

Ion beam erosion can be used as a process for achieving surface smoothing at microscopic length scales and for the preparation of ultrasmooth surfaces, as an alternative to nanostructuring of various surfaces via self-organization. This requires that in the evolution of the surface topography different relaxation mechanisms dominate over the roughening, and smoothing of initially rough surfaces can occur. This contribution focuses on the basic mechanisms as well as potential applications of surface smoothing using low energy ion beams. In the first part, the fundamentals for the smoothing of III/V semiconductors, Si and quartz glass surfaces using low energy ion beams (ion energy: ≤2000 eV) are reviewed using examples. The topography evolution of these surfaces with respect to different process parameters (ion energy, ion incidence angle, erosion time, sample rotation) has been investigated. On the basis of the time evolution of different roughness parameters, the relevant surface relaxation mechanisms responsible for surface smoothing are discussed. In this context, physical constraints as regards the effectiveness of surface smoothing by direct ion bombardment will also be addressed and furthermore ion beam assisted smoothing techniques are introduced. In the second application-orientated part, recent technological developments related to ion beam assisted smoothing of optically relevant surfaces are summarized. It will be demonstrated that smoothing by direct ion bombardment in combination with the use of sacrificial smoothing layers and the utilization of appropriate broad beam ion sources enables the polishing of various technologically important surfaces down to 0.1 nm root mean square roughness level, showing great promise for large area surface processing. Specific examples are given for ion beam smoothing of different optical surfaces, especially for substrates used for advanced optical applications (e.g., in x-ray optics and components for extreme ultraviolet lithography).