Photophysics of single silicon vacancy centers in diamond: implications for single photon emission

Single silicon vacancy (SiV) color centers in diamond have recently shown the ability for high brightness, narrow bandwidth, room temperature single photon emission. This work develops a model describing the three level population dynamics of single SiV centers in diamond nanocrystals on iridium surfaces including an intensity dependent de-shelving process. Furthermore, we investigate the brightness and photostability of single centers and find maximum single photon rates of 6.2 Mcps under continuous excitation. We investigate the collection efficiency of the fluorescence and estimate quantum efficiencies of the SiV centers.Comment: 15 pages, 7 figures, version 2 accepted for publication in Optics Expres

Editorial

Joseph Weizenbaum would have been 100 years old on January 8, 2023. This anniversary was a welcome occasion to remember the life, work, and impact of the great computer scientist and public intellectual at the Weizenbaum Institute.  This special issue compiles a series of articles directly or indirectly related to his work. Contributions center on Weizenbaum as an individual and his public role as a progressive intellectual, encompassing contemporary viewpoints on ethics in digital technology

Quantum technologies in space

Recently, the European Commission supported by many European countries has announced large investments towards the commercialization of quantum technology (QT) to address and mitigate some of the biggest challenges facing today’s digital era – e.g. secure communication and computing power. For more than two decades the QT community has been working on the development of QTs, which promise landmark breakthroughs leading to commercialization in various areas. The ambitious goals of the QT community and expectations of EU authorities cannot be met solely by individual initiatives of single countries, and therefore, require a combined European effort of large and unprecedented dimensions comparable only to the Galileo or Copernicus programs. Strong international competition calls for a coordinated European effort towards the development of QT in and for space, including research and development of technology in the areas of communication and sensing. Here, we aim at summarizing the state of the art in the development of quantum technologies which have an impact in the field of space applications. Our goal is to outline a complete framework for the design, development, implementation, and exploitation of quantum technology in space. © 2021, The Author(s)

Epithelial calcineurin controls microbiota-dependent intestinal tumor development.

Inflammation-associated pathways are active in intestinal epithelial cells (IECs) and contribute to the pathogenesis of colorectal cancer (CRC). Calcineurin, a phosphatase required for the activation of the nuclear factor of activated T cells (NFAT) family of transcription factors, shows increased expression in CRC. We therefore investigated the role of calcineurin in intestinal tumor development. We demonstrate that calcineurin and NFAT factors are constitutively expressed by primary IECs and selectively activated in intestinal tumors as a result of impaired stratification of the tumor-associated microbiota and toll-like receptor signaling. Epithelial calcineurin supports the survival and proliferation of cancer stem cells in an NFAT-dependent manner and promotes the development of intestinal tumors in mice. Moreover, somatic mutations that have been identified in human CRC are associated with constitutive activation of calcineurin, whereas nuclear translocation of NFAT is associated with increased death from CRC. These findings highlight an epithelial cell-intrinsic pathway that integrates signals derived from the commensal microbiota to promote intestinal tumor development.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) grants ZE814/5-1 (S.Z.), BA2863/5-1 (J.F.B.) and CH279/5-1 (T.C.), the European Research Council (ERC) starting grant 336528 (S.Z.), a Postdoctoral Fellowship Award from the Crohn's and Colitis Foundation of America (S.Z.), the European Commission (Marie Curie International Reintegration grant 256363; S.Z.), the DFG Excellence Cluster 'Inflammation at Interfaces' (S.Z. and J.F.B.), the DFG Excellence Cluster 'Center for Regenerative Therapies' (S.Z.); the US National Institutes of Health grants DK044319 (R.S.B.), DK051362 (R.S.B.), DK053056 (R.S.B.) and DK088199 (R.S.B.), the Harvard Digestive Diseases Center (HDDC) grant DK0034854 (R.S.B.), and the AIRC grant IG-14233 (M.E.B.).This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nm.407

Physicians’ views and experiences of discussing weight management within routine clinical consultations: A thematic synthesis

Objective To systematically search and synthesise qualitative studies of physicians’ views and experiences of discussing weight management within a routine consultation. Methods A systematic search of four electronic databases identified 11,169 articles of which 16 studies met inclusion criteria. Quality was appraised using the Critical Appraisal Skills Programme tool and a thematic synthesis conducted of extracted data. Results Four analytical themes were found: (1) physicians’ pessimism about patients’ weight loss success (2) physicians’ feel hopeless and frustrated (3) the dual nature of the physician-patient relationship (4) who should take responsibility for weight management. Conclusion Despite clinical recommendations barriers remain during consultations between physicians and patients about weight management. Many of these barriers are potentially modifiable

Different Device Architectures for Bulk-Heterojunction Solar Cells

We report different solar cell designs which allow a simple electrical connection of subsequent devices deposited on the same substrate. By arranging so-called standard and inverted solar-cell architectures next to each other, a serial connection of the two devices can easily be realized by a single compound electrode. In this work, we tested different interfacial layer materials like polyethylenimine (PEI) and PEDOT:PSS, and silver as a non-transparent electrode material. We also built organic light emitting diodes applying the same device designs demonstrating the versatility of applied layer stacks. The proposed design should allow the preparation of organic bulk-heterojunction modules with minimized photovoltaically inactive regions at the interconnection of individual devices

Gas-phase formation of large neutral alkaline-earth metal tryptophan complexes

We report on the first observation of isolated large neutral metal amino acid complexes such as TrpnMek, with Me = Ca, Ba, Sr, cluster combinations covering n=1…33, k=0..2 and masses beyond 6500 u. The cluster beam is generated using UV laser desorption from a mixed powder of alkaline-earth metal salts and tryptophan inside a cluster mixing channel. The particles are detected using VUV photoionization followed by time-of-flight mass spectroscopy. The enhanced stability of metal amino acid clusters over pure amino acid clusters is substantiated in molecular dynamics simulations by determining the gain in binding energy related to the inclusion of the metal atom

Copolymers containing phosphorescent iridium(III) complexes obtained by free and controlled radical polymerization techniques

A methacrylate-functionalized phosphorescent Ir(III)-complex has been synthesized, characterized, and applied as a monomer in radical copolymerizations. Together with methyl methacrylate, the complex has been copolymerized under free radical polymerization conditions. Aiming for host-guest-systems, applicable e.g. in organiclight emitting devices (OLEDs), the complex was further copolymerized with a methacrylate-functionalized carbazole derivative using the atom transfer radical polymerization technique. Applying gel permeation chromatography, in combination with a photodiode array detector, could clearly prove the formation of the copolymers. The optical properties of the photoactive monomers as well as the copolymers were investigated by absorption and emission spectroscopy (in solution). For the carbazole-copolymer, the emission originates almost exclusively from the complex. This provides evidence of an efficient intrachain energy transfer, which makes the system an interesting candidate for potential OLED applications. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA