Driving current through single organic molecules

We investigate electronic transport through two types of conjugated molecules. Mechanically controlled break-junctions are used to couple thiol endgroups of single molecules to two gold electrodes. Current-voltage characteristics (IVs) of the metal-molecule-metal system are observed. These IVs reproduce the spatial symmetry of the molecules with respect to the direction of current flow. We hereby unambigously detect an intrinsic property of the molecule, and are able to distinguish the influence of both the molecule and the contact to the metal electrodes on the transport properties of the compound system.Comment: 4 pages, 5 figure

The first major incision of the Swiss Deckenschotter landscape

The Swiss Deckenschotter ("cover gravels”) is the oldest Quaternary units in the northern Swiss Alpine Foreland. They are a succession of glaciofluvial gravel layers intercalated with glacial and/or overbank deposits. This lithostratigraphic sequence is called Deckenschotter because it "covers” Molasse or Mesozoic bedrock and forms mesa-type hill-tops. Deckenschotter occurs both within and beyond the extent of the Last Glacial Maximum glaciers. The Swiss Deckenschotter consist of two sub-units: Höhere (Higher) and Tiefere (Lower) Deckenschotter. Although the Höhere Deckenschotter sub-unit (HDS) is topographically higher than the Tiefere Deckenschotter, it is older. The only available age for the Swiss Deckenschotter is 2.5-1.8Ma based on mammal remains found in HDS at the Irchel site. In this study, we present an exposure age for the topographically lowest HDS, calculated from a cosmogenic 10Be depth-profile. Our results show that the first phase of the Deckenschotter glaciations in the Swiss Alps terminated at least 1,020 $$_{ - 120}^{ + 80}$$ - 120 + 80 ka ago, which is indicated by a significant fluvial incision. This line of evidence seems to be close to synchronous with the beginning of the Mid-Pleistocene Revolution, when the frequency of the glacial-interglacial cyclicity changed from 41 to 100ka and the amplitude from low to high, between marine isotope stages 23 and 22

3D-Printing of Hierarchically Designed and Osteoconductive Bone Tissue Engineering Scaffolds

In Bone Tissue Engineering (BTE), autologous bone-regenerative cells are combined with a scaffold for large bone defect treatment (LBDT). Microporous, polylactic acid (PLA) scaffolds showed good healing results in small animals. However, transfer to large animal models is not easily achieved simply by upscaling the design. Increasing diffusion distances have a negative impact on cell survival and nutrition supply, leading to cell death and ultimately implant failure. Here, a novel scaffold architecture was designed to meet all requirements for an advanced bone substitute. Biofunctional, porous subunits in a load-bearing, compression-resistant frame structure characterize this approach. An open, macro- and microporous internal architecture (100 µm–2 mm pores) optimizes conditions for oxygen and nutrient supply to the implant’s inner areas by diffusion. A prototype was 3D-printed applying Fused Filament Fabrication using PLA. After incubation with Saos-2 (Sarcoma osteogenic) cells for 14 days, cell morphology, cell distribution, cell survival (fluorescence microscopy and LDH-based cytotoxicity assay), metabolic activity (MTT test), and osteogenic gene expression were determined. The adherent cells showed colonization properties, proliferation potential, and osteogenic differentiation. The innovative design, with its porous structure, is a promising matrix for cell settlement and proliferation. The modular design allows easy upscaling and offers a solution for LBDT

Six sequence variants on chromosome 9p21.3 are associated with a positive family history of myocardial infarction: a multicenter registry

<p>Abstract</p> <p>Background</p> <p>Recent genome-wide association studies have identified several genetic loci linked to coronary artery disease (CAD) and myocardial infarction (MI). The 9p21.3 locus was verified by numerous replication studies to be the first common locus for CAD and MI. In the present study, we investigated whether six single nucleotide polymorphisms (SNP) rs1333049, rs1333040, rs10757274, rs2383206, rs10757278, and rs2383207 representing the 9p21.3 locus were associated with the incidence of an acute MI in patients with the main focus on the familial aggregation of the disease.</p> <p>Methods</p> <p>The overall cohort consisted of 976 unrelated male patients presenting with an acute coronary syndrome (ACS) with ST-elevated (STEMI) as well as non-ST-elevated myocardial infarction (NSTEMI). Genotyping data of the investigated SNPs were generated and statistically analyzed in comparison to previously published findings of matchable control cohorts.</p> <p>Results</p> <p>Statistical evaluation confirmed a highly significant association of all analyzed SNP's with the occurrence of MI (p < 0.0001; OR: 1.621-2.039). When only MI patients with a positive family disposition were comprised in the analysis a much stronger association of the accordant risk alleles with incident disease was found with odds ratios up to 2.769.</p> <p>Conclusions</p> <p>The findings in the present study confirmed a strong association of the 9p21.3 locus with MI particularly in patients with a positive family history thereby, emphasizing the pathogenic relevance of this locus as a common genetic cardiovascular risk factor.</p

Multifunctional, covalently stabilised capsules from biodegradable materials

© 2010 Dr. Christopher Joachim OchsOne of the most promising and fast-developing areas of nanotechnology is the design of carrier systems for biomedical applications. These particulate delivery vehicles can be engineered with highly defined properties with a range of sizes, shapes and functionalities. Polymeric nanocapsules assembled using the Layer-by-Layer (LbL) technique are widely regarded as promising candidates for the delivery of biologically relevant agents. By choosing to use naturally occurring polyelectrolyte as LbL materials, such as poly(L-Lysine) (PLL) and poly(L-glutamic acid) (PGA, the resulting capsules can be degraded using enzymes that are present in certain environments within the body. In order to produce covalently stabilised multilayer films, PLL and PGA were modified with alkyne and azide moieties, respectively, enabling the formation of a covalent triazole bond between adjoining layers in the presence of copper during LbL assembly (click chemistry reaction). Stable one-component films and capsules were prepared and characterised. Properties such as enzymatic degradation, tuneable pH-responsive swelling, cytotoxicity, permeability and protein adhesion to the capsule surface were investigated. PLL click films were also equipped with targeting moieties as a proof of concept. The concept of stratified LbL assembly was introduced to tailor the degradation kinetics of the biodegradable hybrid capsules. To investigate drug loading, polymer-drug conjugates of PGA and anticancer drugs (doxorubicin or paclitaxel) were synthesised. The modular LbL assembly approach allowed for loading of these conjugates to multilayer films. A high level of control over drug position and dose was achieved and drugs could subsequently be release by enzymatic degradation. The uptake to colorectal cancer cells and the effect of drug-loaded capsules on cell viability was also investigated. In addition, a drug-resistant cell line was established and the capsular delivery method of anticancer-drugs was found to restore sensitivity of the drug-resistant cell line towards these drugs. In a different approach, PGA was modified with dopamine for continuous assembly of biodegradable capsules with defined properties. Overall, this thesis suggests various promising approaches for the assembly of biodegradable, multifunctional and covalently-stabilised capsules with potential application in targeted drug delivery