Manufacturing of embedded multimode waveguides by reactive lamination of cyclic olefin polymer and polymethylmethacrylate

We demonstrate the manufacturing of embedded multimode optical waveguides through linking of polymethylmethacrylate (PMMA) foils and cyclic olefin polymer (COP) filaments based on a lamination process. Since the two polymeric materials cannot be fused together through interdiffusion of polymer chains, we utilize a reactive lamination agent based on PMMA copolymers containing photoreactive 2-acryloyloxyanthraquinone units, which allows the creation of monolithic PMMA-COP substrates through C-H insertion reactions across the interface between the two materials. We elucidate the lamination process and evaluate the chemical link between filament and foils by carrying out extraction tests with a custom-built tensile testing machine. We also show attenuation measurements of the manufactured waveguides for different manufacturing parameters. The lamination process is in particular suited for large-scale and low-cost fabrication of board-level devices with optical waveguides or other micro-optical structures, e.g., optofluidic devices. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).DFG/SFB/TRR 12

Analysis of negative historical control group data from the in vitro micronucleus assay using TK6 cells.

The recent revisions of the Organisation for Economic Co-operation and Development (OECD) genetic toxicology test guidelines emphasize the importance of historical negative controls both for data quality and interpretation. The goal of a HESI Genetic Toxicology Technical Committee (GTTC) workgroup was to collect data from participating laboratories and to conduct a statistical analysis to understand and publish the range of values that are normally seen in experienced laboratories using TK6 cells to conduct the in vitro micronucleus assay. Data from negative control samples from in vitro micronucleus assays using TK6 cells from 13 laboratories were collected using a standard collection form. Although in some cases statistically significant differences can be seen within laboratories for different test conditions, they were very small. The mean incidence of micronucleated cells/1000 cells ranged from 3.2/1000 to 13.8/1000. These almost four-fold differences in micronucleus levels cannot be explained by differences in scoring method, presence or absence of exogenous metabolic activation (S9), length of treatment, presence or absence of cytochalasin B or different solvents used as vehicles. The range of means from the four laboratories using flow cytometry methods (3.7-fold: 3.5-12.9 micronucleated cells/1000 cells) was similar to that from the nine laboratories using other scoring methods (4.3-fold: 3.2-13.8 micronucleated cells/1000 cells). No laboratory could be identified as an outlier or as showing unacceptably high variability. Quality Control (QC) methods applied to analyse the intra-laboratory variability showed that there was evidence of inter-experimental variability greater than would be expected by chance (i.e. over-dispersion). However, in general, this was low. This study demonstrates the value of QC methods in helping to analyse the reproducibility of results, building up a 'normal' range of values, and as an aid to identify variability within a laboratory in order to implement processes to maintain and improve uniformity

Development and Validation of the German Work-Related Curiosity Scale

Curiosity, a personality trait underlying behavioral tendencies related to knowledge acquisition, learning, and thinking, can be expected to be of high relevance in the world of work. There is, however, to date no work-related curiosity measure. The present article reports results regarding the development and validation of the new 10-item Work-Related Curiosity Scale. Based on two studies, the measure had a one-factor solution, acceptable internal consistency, and expected construct validity. In Study 2, incremental criterion-related validities were found over and above five general curiosity scales (ΔR2 between .12 and .15), which is in line with the frame-of-reference approach underlying the development of the scale. Interestingly, the lack of evidence for criterion-related validity in Study 1 indicates that these results do not generalize across positions

Multicolor FISH using tándem probes to detect Chromosome alterations in humans cells and populations exposed to genotoxic agents

12 páginas, 2 figuras y 2 tablas estadísticasFluorescence in situ hybridization (FISH) with chromosome- or region-specific DNA probes is being increasingly used in cytogenetic studies to detect aneuploidy in interphase human cells. This technique utilizes chemically modified DNA sequences (probes) which hybridize to distinct regions, often blocks of repetitive DNA, located on specific chromosomes. Hybridization with these probes in situ results in the staining of a compact chromosomal región which can be easily detected on metaphase chromosomes or within interphase nuclei. The number of chromosomes within a given cell is then determined by counting the number of hybridized regions. Where conventional cytogenetics is limited to actively proliferating cells or those which could be stimulated to divide in vitro such as peripheral blood lymphocytes, FISH studies with centromeric probes can be conducted on interphase cells, significantly increasing the types of cells and tissues available for analysis.Peer reviewe

Synthesis, Molecular Editing, and Biological Assessment of the Potent Cytotoxin Leiodermatolide

It was by way of total synthesis that the issues concerning the stereostructure of leiodermatolide (<b>1</b>) have recently been solved; with the target now being unambiguously defined, the mission of synthesis changes as to secure a meaningful supply of this exceedingly scarce natural product derived from a deep-sea sponge. To this end, a scalable route of 19 steps (longest linear sequence) has been developed, which features a catalytic asymmetric propargylation of a highly enolizable β-keto-lactone, a ring closing alkyne metathesis and a modified Stille coupling as the key transformations. Deliberate digression from this robust blueprint brought a first set of analogues into reach, which allowed the lead qualities of <b>1</b> to be assessed. The acquired biodata show that <b>1</b> is a potent cytotoxin in human tumor cell proliferation assays, distinguished by GI₅₀ values in the ≤3 nM range even for cell lines expressing the Pgp efflux transporter. Studies with human U2OS cells revealed that <b>1</b> causes mitotic arrest, micronucleus induction, centrosome amplification and tubulin disruption, even though no evidence for direct tubulin binding has been found in cell-free assays; moreover, the compound does not seem to act through kinase inhibition. Indirect evidence points at centrosome declustering as a possible mechanism of action, which provides a potentially rewarding outlook in that centrosome declustering agents hold promise of being inherently selective for malignant over healthy human tissue