XDJ1, a gene encoding a novel non-essential DnaJ homologue from Saccharomyces cerevisiae

The gene encoding a novel DnaJ-like protein, termed Xdj1, has been identified by amplification of Saccharomyces cerevisiae genomic DNA. An open reading frame of 1380 bp was detected. Disruption of XDJ1 did not yield any detectable new phenotype. A double-deletion strain containing a disruption of both XDJ1 and YDJ1, another gene coding for a DnaJ-like protein, was still viable. Under a variety of growth conditions, no XDJ1 transcripts could be detected by Northern blot analysis and no translation product was found by immunoblotting with antibody against Xdj1 produced in Escherichia coli. Thus, XDJ1 is either expressed only under very specific conditions or represents a silent gene

Optimizing the spin sensitivity of grain boundary junction nanoSQUIDs -- towards detection of small spin systems with single-spin resolution

We present an optimization study of the spin sensitivity of nanoSQUIDs based on resistively shunted grain boundary Josephson junctions. In addition the dc SQUIDs contain a narrow constriction onto which a small magnetic particle can be placed (with its magnetic moment in the plane of the SQUID loop and perpendicular to the grain boundary) for efficient coupling of its stray magnetic field to the SQUID loop. The separation of the location of optimum coupling from the junctions allows for an independent optimization of the coupling factor $\phi_\mu$ and junction properties. We present different methods for calculating $\phi_\mu$ (for a magnetic nanoparticle placed 10\,nm above the constriction) as a function of device geometry and show that those yield consistent results. Furthermore, by numerical simulations we obtain a general expression for the dependence of the SQUID inductance on geometrical parameters of our devices, which allows to estimate their impact on the spectral density of flux noise $S_\Phi$ of the SQUIDs in the thermal white noise regime. Our analysis of the dependence of $S_\Phi$ and $\phi_\mu$ on the geometric parameters of the SQUID layout yields a spin sensitivity $S_\mu^{1/2}=S_\Phi^{1/2}/\phi_\mu$ of a few $\mu_{\rm{B}}/\rm{Hz^{1/2}}$ ($\mu_B$ is the Bohr magneton) for optimized parameters, respecting technological constraints. However, by comparison with experimentally realized devices we find significantly larger values for the measured white flux noise, as compared to our theoretical predictions. Still, a spin sensitivity on the order of $10\,\mu_{\rm B}/\rm{Hz^{1/2}}$ for optimized devices seems to be realistic.Comment: 10 pages, 5 figures, Superconductor Science and Technology (submitted

Controlled generation of a pn-junction in a waveguide integrated graphene photodetector

With its electrically tunable light absorption and ultrafast photoresponse, graphene is a promising candidate for high-speed chip-integrated photonics. The generation mechanisms of photosignals in graphene photodetectors have been studied extensively in the past years. However, the knowledge about efficient light conversion at graphene pn-junctions has not yet been translated into high-performance devices. Here, we present a graphene photodetector integrated on a silicon slot-waveguide, acting as a dual-gate to create a pn-junction in the optical absorption region of the device. While at zero bias the photo-thermoelectric effect is the dominant conversion process, an additional photoconductive contribution is identified in a biased configuration. Extrinsic responsivities of 35 mA/W, or 3.5 V/W, at zero bias and 76 mA/W at 300 mV bias voltage are achieved. The device exhibits a 3 dB-bandwidth of 65 GHz, which is the highest value reported for a graphene-based photodetector.Comment: 19 pages, 16 figure

Die Expression des Epitops Sialyl Lewis X als prognostischer Faktor beim kolorektalen Karzinom

In der hier vorliegenden Arbeit wurde die prognostische Wertigkeit der immunhistochemisch detektierten Expression des auf den Zellwänden kolorektaler Karzinome auftretenden Glykoproteinepitops Sialyl LeX analysiert. In die Untersuchung wurden 215 Patienten mit einbezogen, die sich zwischen Januar 2000 und Dezember 2004 in der Chirurgischen Universitätsklinik Rostock der primären Resektion eines kolorektalen Karzinoms im UICC-Stadium III oder IV unterzogen. Für die Auswertung der Färbung wurde ein fünfstufiger, einfach anzuwendender Score entwickelt