Molecular quantum spin network controlled by a single qubit

Scalable quantum technologies will require an unprecedented combination of precision and complexity for designing stable structures of well-controllable quantum systems. It is a challenging task to find a suitable elementary building block, of which a quantum network can be comprised in a scalable way. Here we present the working principle of such a basic unit, engineered using molecular chemistry, whose control and readout are executed using a nitrogen vacancy (NV) center in diamond. The basic unit we investigate is a synthetic polyproline with electron spins localized on attached molecular sidegroups separated by a few nanometers. We demonstrate the readout and coherent manipulation of very few ($\leq 6$) of these $S=1/2$ electronic spin systems and access their direct dipolar coupling tensor. Our results show, that it is feasible to use spin-labeled peptides as a resource for a molecular-qubit based network, while at the same time providing simple optical readout of single quantum states through NV-magnetometry. This work lays the foundation for building arbitrary quantum networks using well-established chemistry methods, which has many applications ranging from mapping distances in single molecules to quantum information processing.Comment: Author name typ

Automatic Collimation Detection in Digital Radiographs with the Directed Hough Transform and Learning-Based Edge Detection

Abstract. Collimation is widely used for X-ray examinations to reduce the overall radiation exposure to the patient and improve the contrast resolution in the region of interest (ROI), that has been exposed directly to X-rays. It is desirable to detect the region of interest and exclude the unexposed area to optimize the image display. Although we only focus on the X-ray images generated with a rectangular collimator, it remains a challenging task because of the large variability of collimated images. In this study, we detect the region of interest as an optimal quadrilateral, which is the intersection of the optimal group of four half-planes. Each half-plane is defined as the positive side of a directed straight line. We develop an extended Hough transform for directed straight lines on a model-aware gray level edge-map, which is estimated with random forests [1] on features of pairs of superpixels. Experiments show that our algorithm can extract the region of interest quickly and accurately, despite variations in size, shape and orientation, and incompleteness of boundaries

Synthesis and characterization of pyrenol-based "super"-photoacids for application as versatile tools in chemistry and life sciences

Photosäuren sind Moleküle, die nach elektronischer Anregung eine Erhöhung der Azidität um 4–10 logarithmische Einheiten erfahren. Ist ein geeigneter Akzeptor im betrachteten System vorhanden, findet infolgedessen ein Protonentransfer im angeregten Zustand (ESPT) statt. Die emittierte Fluoreszenz entstammt dabei der, durch den ESPT gebildeten, angeregten Base und ist im Vergleich zur konjugierten Säure um bis zu über 100 nm rotverschoben. In dieser Arbeit wurden fünf neue Photosäuren mit sichtbarer Fluoreszenz auf Pyrenol-Basis synthetisiert. Zur Charakterisierung dieser „Super“-Photosäuren, die Protonen in einem ESPT auch in organischen Lösungsmitteln wie DMSO übertragen können, wurden statische und zeitaufgelöste fluoreszenzspektroskopische Methoden eingesetzt. Durch Auswerten der statischen optischen Spektren in einer Analyse der Solvatochromie konnte gezeigt werden, dass die Stärke des intramolekularen Ladungstransfers mit der Photoazidität korreliert. Zudem wurden Synthesewege zur Herstellung unsymmetrisch substituierter Pyrenol-Derivate entwickelt und so monomolekulare, ratiometrische Sonden für orthogonale Reaktivitäten erzeugt. Diese erlauben die Detektion von zwei orthogonalen Enzymen bzw. die Differenzierung verschiedener pH-Stufen durch bis zu vier sogar mit dem bloßen Auge unterscheidbare Farben. Die Derivate ermöglichen zudem simple Operationen nach Boolescher Algebra (z.B. AND-Gatter) sowie die Nachahmung komplexerer logischer Schaltungen (z.B. Feynman-Gatter).Photoacids are molecules which show an enhancement of acidity upon electronic excitation by 4–10 logarithmic units. If a suitable acceptor is present, these molecules hence undergo an excited-state proton transfer (ESPT). The observed fluorescence arises from the formed excited base. This emission is bathochromically shifted by up to 100 nm and more compared to the conjugated acid for energetic reasons. In this thesis, five novel photoacids on the basis of pyrenol with electronic transitions in the visible region of the electromagnetic spectrum were synthesized. Steady-state and time-resolved fluorescence spectroscopy were used to characterize these “super”-photoacids, which are capable of ESPT even in organic solvents like DMSO. Examination of the steady-state optical spectra in a solvatochromic analysis showed a correlation of the extent of the intramolecular charge transfer with the photoacidity. In addition, several synthetic pathways for the creation of unsymmetrically substituted pyrenol-derivatives were developed. Finally, monomolecular, ratiometric probes for two orthogonal reactivities were synthesized on the basis of pyrenol by use of these new synthesis strategies. Besides the detection of two orthogonal enzymes respectively different pH-values by up to four fluorescence colors, distinguishable even by the naked human eye, these derivatives are capable of simple Boolean logic operations (e.g. AND-gate) and even more complex logic operations (e.g. Feynman-gate)

Genome of Acanthamoeba castellanii highlights extensive lateral gene transfer and early evolution of tyrosine kinase signaling

Abstract Background The Amoebozoa constitute one of the primary divisions of eukaryotes, encompassing taxa of both biomedical and evolutionary importance, yet its genomic diversity remains largely unsampled. Here we present an analysis of a whole genome assembly of Acanthamoeba castellanii (Ac) the first representative from a solitary free-living amoebozoan. Results Ac encodes 15,455 compact intron-rich genes, a significant number of which are predicted to have arisen through inter-kingdom lateral gene transfer (LGT). A majority of the LGT candidates have undergone a substantial degree of intronization and Ac appears to have incorporated them into established transcriptional programs. Ac manifests a complex signaling and cell communication repertoire, including a complete tyrosine kinase signaling toolkit and a comparable diversity of predicted extracellular receptors to that found in the facultatively multicellular dictyostelids. An important environmental host of a diverse range of bacteria and viruses, Ac utilizes a diverse repertoire of predicted pattern recognition receptors, many with predicted orthologous functions in the innate immune systems of higher organisms. Conclusions Our analysis highlights the important role of LGT in the biology of Ac and in the diversification of microbial eukaryotes. The early evolution of a key signaling facility implicated in the evolution of metazoan multicellularity strongly argues for its emergence early in the Unikont lineage. Overall, the availability of an Ac genome should aid in deciphering the biology of the Amoebozoa and facilitate functional genomic studies in this important model organism and environmental host

Genome of Acanthamoeba castellanii highlights extensive lateral gene transfer and early evolution of tyrosine kinase signaling

Background The Amoebozoa constitute one of the primary divisions of eukaryotes, encompassing taxa of both biomedical and evolutionary importance, yet its genomic diversity remains largely unsampled. Here we present an analysis of a whole genome assembly of Acanthamoeba castellanii (Ac) the first representative from a solitary free-living amoebozoan. Results Ac encodes 15,455 compact intron-rich genes, a significant number of which are predicted to have arisen through inter-kingdom lateral gene transfer (LGT). A majority of the LGT candidates have undergone a substantial degree of intronization and Ac appears to have incorporated them into established transcriptional programs. Ac manifests a complex signaling and cell communication repertoire, including a complete tyrosine kinase signaling toolkit and a comparable diversity of predicted extracellular receptors to that found in the facultatively multicellular dictyostelids. An important environmental host of a diverse range of bacteria and viruses, Ac utilizes a diverse repertoire of predicted pattern recognition receptors, many with predicted orthologous functions in the innate immune systems of higher organisms. Conclusions Our analysis highlights the important role of LGT in the biology of Ac and in the diversification of microbial eukaryotes. The early evolution of a key signaling facility implicated in the evolution of metazoan multicellularity strongly argues for its emergence early in the Unikont lineage. Overall, the availability of an Ac genome should aid in deciphering the biology of the Amoebozoa and facilitate functional genomic studies in this important model organism and environmental host