419 results on '"Kraus, H."'
Search Results
2. Optimal Operation of Cryogenic Calorimeters Through Deep Reinforcement Learning.
- Author
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Angloher G, Banik S, Benato G, Bento A, Bertolini A, Breier R, Bucci C, Burkhart J, Canonica L, D'Addabbo A, Di Lorenzo S, Einfalt L, Erb A, V Feilitzsch F, Fichtinger S, Fuchs D, Garai A, Ghete VM, Gorla P, Guillaumon PV, Gupta S, Hauff D, Ješkovský M, Jochum J, Kaznacheeva M, Kinast A, Kuckuk S, Kluck H, Kraus H, Langenkämper A, Mancuso M, Marini L, Mauri B, Meyer L, Mokina V, Niedermayer K, Olmi M, Ortmann T, Pagliarone C, Pattavina L, Petricca F, Potzel W, Povinec P, Pröbst F, Pucci F, Reindl F, Rothe J, Schäffner K, Schieck J, Schönert S, Schwertner C, Stahlberg M, Stodolsky L, Strandhagen C, Strauss R, Usherov I, Wagner F, Wagner V, Willers M, Zema V, Heitzinger C, and Waltenberger W
- Abstract
Cryogenic phonon detectors with transition-edge sensors achieve the best sensitivity to sub-GeV/c 2 dark matter interactions with nuclei in current direct detection experiments. In such devices, the temperature of the thermometer and the bias current in its readout circuit need careful optimization to achieve optimal detector performance. This task is not trivial and is typically done manually by an expert. In our work, we automated the procedure with reinforcement learning in two settings. First, we trained on a simulation of the response of three Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) detectors used as a virtual reinforcement learning environment. Second, we trained live on the same detectors operated in the CRESST underground setup. In both cases, we were able to optimize a standard detector as fast and with comparable results as human experts. Our method enables the tuning of large-scale cryogenic detector setups with minimal manual interventions., Competing Interests: Competing interestsOn behalf of all authors, the corresponding author states that there is no conflict of interest. The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request., (© The Author(s) 2024.)
- Published
- 2024
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3. Thermal Rearrangement of Thiocarbonyl-Stabilised Triphenylphosphonium Ylides Leading to ( Z )-1-Diphenylphosphino-2-(phenylsulfenyl)alkenes and Their Coordination Chemistry.
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Aitken RA, Dawson G, Keddie NS, Kraus H, Milton HL, Slawin AMZ, Wheatley J, and Woollins JD
- Abstract
While thiocarbonyl-stabilised phosphonium ylides generally react upon flash vacuum pyrolysis by the extrusion of Ph
3 PS to give alkynes in an analogous way to their carbonyl-stabilised analogues, two examples with a hydrogen atom on the ylidic carbon are found to undergo a quite different process. The net transfer of a phenyl group from P to S gives ( Z )-configured 1-diphenylphosphino-2-(phenylsulfenyl)alkenes in a novel isomerisation process via intermediate λ5 -1,2-thiaphosphetes. These prove to be versatile hemilabile ligands with a total of seven complexes prepared involving five different transition metals. Four of these are characterised by X-ray diffraction with two involving the bidentate ligand forming a five-membered ring metallacycle and two with the ligand coordinating to the metal only through phosphorus.- Published
- 2023
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4. First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment.
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Aalbers J, Akerib DS, Akerlof CW, Al Musalhi AK, Alder F, Alqahtani A, Alsum SK, Amarasinghe CS, Ames A, Anderson TJ, Angelides N, Araújo HM, Armstrong JE, Arthurs M, Azadi S, Bailey AJ, Baker A, Balajthy J, Balashov S, Bang J, Bargemann JW, Barry MJ, Barthel J, Bauer D, Baxter A, Beattie K, Belle J, Beltrame P, Bensinger J, Benson T, Bernard EP, Bhatti A, Biekert A, Biesiadzinski TP, Birch HJ, Birrittella B, Blockinger GM, Boast KE, Boxer B, Bramante R, Brew CAJ, Brás P, Buckley JH, Bugaev VV, Burdin S, Busenitz JK, Buuck M, Cabrita R, Carels C, Carlsmith DL, Carlson B, Carmona-Benitez MC, Cascella M, Chan C, Chawla A, Chen H, Cherwinka JJ, Chott NI, Cole A, Coleman J, Converse MV, Cottle A, Cox G, Craddock WW, Creaner O, Curran D, Currie A, Cutter JE, Dahl CE, David A, Davis J, Davison TJR, Delgaudio J, Dey S, de Viveiros L, Dobi A, Dobson JEY, Druszkiewicz E, Dushkin A, Edberg TK, Edwards WR, Elnimr MM, Emmet WT, Eriksen SR, Faham CH, Fan A, Fayer S, Fearon NM, Fiorucci S, Flaecher H, Ford P, Francis VB, Fraser ED, Fruth T, Gaitskell RJ, Gantos NJ, Garcia D, Geffre A, Gehman VM, Genovesi J, Ghag C, Gibbons R, Gibson E, Gilchriese MGD, Gokhale S, Gomber B, Green J, Greenall A, Greenwood S, van der Grinten MGD, Gwilliam CB, Hall CR, Hans S, Hanzel K, Harrison A, Hartigan-O'Connor E, Haselschwardt SJ, Hernandez MA, Hertel SA, Heuermann G, Hjemfelt C, Hoff MD, Holtom E, Hor JY, Horn M, Huang DQ, Hunt D, Ignarra CM, Jacobsen RG, Jahangir O, James RS, Jeffery SN, Ji W, Johnson J, Kaboth AC, Kamaha AC, Kamdin K, Kasey V, Kazkaz K, Keefner J, Khaitan D, Khaleeq M, Khazov A, Khurana I, Kim YD, Kocher CD, Kodroff D, Korley L, Korolkova EV, Kras J, Kraus H, Kravitz S, Krebs HJ, Kreczko L, Krikler B, Kudryavtsev VA, Kyre S, Landerud B, Leason EA, Lee C, Lee J, Leonard DS, Leonard R, Lesko KT, Levy C, Li J, Liao FT, Liao J, Lin J, Lindote A, Linehan R, Lippincott WH, Liu R, Liu X, Liu Y, Loniewski C, Lopes MI, Lopez Asamar E, López Paredes B, Lorenzon W, Lucero D, Luitz S, Lyle JM, Majewski PA, Makkinje J, Malling DC, Manalaysay A, Manenti L, Mannino RL, Marangou N, Marzioni MF, Maupin C, McCarthy ME, McConnell CT, McKinsey DN, McLaughlin J, Meng Y, Migneault J, Miller EH, Mizrachi E, Mock JA, Monte A, Monzani ME, Morad JA, Morales Mendoza JD, Morrison E, Mount BJ, Murdy M, Murphy ASJ, Naim D, Naylor A, Nedlik C, Nehrkorn C, Neves F, Nguyen A, Nikoleyczik JA, Nilima A, O'Dell J, O'Neill FG, O'Sullivan K, Olcina I, Olevitch MA, Oliver-Mallory KC, Orpwood J, Pagenkopf D, Pal S, Palladino KJ, Palmer J, Pangilinan M, Parveen N, Patton SJ, Pease EK, Penning B, Pereira C, Pereira G, Perry E, Pershing T, Peterson IB, Piepke A, Podczerwinski J, Porzio D, Powell S, Preece RM, Pushkin K, Qie Y, Ratcliff BN, Reichenbacher J, Reichhart L, Rhyne CA, Richards A, Riffard Q, Rischbieter GRC, Rodrigues JP, Rodriguez A, Rose HJ, Rosero R, Rossiter P, Rushton T, Rutherford G, Rynders D, Saba JS, Santone D, Sazzad ABMR, Schnee RW, Scovell PR, Seymour D, Shaw S, Shutt T, Silk JJ, Silva C, Sinev G, Skarpaas K, Skulski W, Smith R, Solmaz M, Solovov VN, Sorensen P, Soria J, Stancu I, Stark MR, Stevens A, Stiegler TM, Stifter K, Studley R, Suerfu B, Sumner TJ, Sutcliffe P, Swanson N, Szydagis M, Tan M, Taylor DJ, Taylor R, Taylor WC, Temples DJ, Tennyson BP, Terman PA, Thomas KJ, Tiedt DR, Timalsina M, To WH, Tomás A, Tong Z, Tovey DR, Tranter J, Trask M, Tripathi M, Tronstad DR, Tull CE, Turner W, Tvrznikova L, Utku U, Va'vra J, Vacheret A, Vaitkus AC, Verbus JR, Voirin E, Waldron WL, Wang A, Wang B, Wang JJ, Wang W, Wang Y, Watson JR, Webb RC, White A, White DT, White JT, White RG, Whitis TJ, Williams M, Wisniewski WJ, Witherell MS, Wolfs FLH, Wolfs JD, Woodford S, Woodward D, Worm SD, Wright CJ, Xia Q, Xiang X, Xiao Q, Xu J, Yeh M, Yin J, Young I, Zarzhitsky P, Zuckerman A, and Zweig EA
- Abstract
The LUX-ZEPLIN experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This Letter reports results from LUX-ZEPLIN's first search for weakly interacting massive particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross sections for WIMP masses above 9 GeV/c^{2}. The most stringent limit is set for spin-independent scattering at 36 GeV/c^{2}, rejecting cross sections above 9.2×10^{-48} cm at the 90% confidence level.
- Published
- 2023
- Full Text
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5. How Large is the Potential of Brain Dead Donors and what Prevents Utilization? A Multicenter Retrospective Analysis at Seven University Hospitals in North Rhine-Westphalia.
- Author
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Englbrecht JS, Schrader D, Kraus H, Schäfer M, Schedler D, Bach F, and Soehle M
- Subjects
- Humans, Hospitals, University, Retrospective Studies, Tissue Donors, Family, Brain Death, Tissue and Organ Procurement
- Abstract
Organ donation after brain death is constantly lower in Germany compared to other countries. Instead, representative surveys show a positive attitude towards donation. Why this does not translate into more donations remains questionable. We retrospectively analyzed all potential brain dead donors treated in the university hospitals of Aachen, Bielefeld, Bonn, Essen, Düsseldorf, Cologne and Münster between June 2020 and July 2021. 300 potential brain dead donors were identified. Donation was utilized in 69 cases (23%). Refused consent ( n = 190), and failed utilization despite consent ( n = 41) were reasons for a donation not realized. Consent was significantly higher in potential donors with a known attitude towards donation ( n = 94) compared to a decision by family members ( n = 195) (49% vs. 33%, p = 0.012). The potential donor´s age, status of interviewer, and the timing of the interview with decision-makers had no influence on consent rates, and it was comparable between hospitals. Refused consent was the predominant reason for a donation not utilized. Consent rate was lower than in surveys, only a known attitude towards donation had a significant positive influence. This indicates that survey results do not translate well into everyday clinical practice and promoting a previously documented decision on organ donation is important., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Englbrecht, Schrader, Kraus, Schäfer, Schedler, Bach and Soehle.)
- Published
- 2023
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6. Secular equilibrium assessment in a CaWO 4 target crystal from the dark matter experiment CRESST using Bayesian likelihood normalisation.
- Author
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Angloher G, Banik S, Benato G, Bento A, Bertolini A, Breier R, Bucci C, Burkhart J, Canonica L, D'Addabbo A, Di Lorenzo S, Einfalt L, Erb A, Feilitzsch FV, Ferreiro Iachellini N, Fichtinger S, Fuchs D, Fuss A, Garai A, Ghete VM, Gorla P, Gupta S, Hauff D, Ješkovský M, Jochum J, Kaznacheeva M, Kinast A, Kluck H, Kraus H, Langenkämper A, Mancuso M, Marini L, Mokina V, Nilima A, Olmi M, Ortmann T, Pagliarone C, Pattavina L, Petricca F, Potzel W, Povinec P, Pröbst F, Pucci F, Reindl F, Rothe J, Schäffner K, Schieck J, Schmiedmayer D, Schönert S, Schwertner C, Stahlberg M, Stodolsky L, Strandhagen C, Strauss R, Usherov I, Wagner F, Willers M, Zema V, Ferella F, Laubenstein M, and Nisi S
- Abstract
CRESST is a leading direct detection sub-GeVc
-2 dark matter experiment. During its second phase, cryogenic bolometers were used to detect nuclear recoils off the CaWO4 target crystal nuclei. The previously established electromagnetic background model relies on Secular Equilibrium (SE) assumptions. In this work, a validation of SE is attempted by comparing two likelihood-based normalisation results using a recently developed spectral template normalisation method based on Bayesian likelihood. Albeit we find deviations from SE in some cases we conclude that these deviations are artefacts of the fit and that the assumptions of SE is physically meaningful., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)- Published
- 2023
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7. Advance Directives and Consent to Organ Donation in Seven University Hospitals in North Rhine-Westphalia-a Retrospective, Multicenter Analysis.
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Englbrecht JS, Schrader D, Kraus H, Schäfer M, Schedler D, Bach F, and Soehle M
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- Humans, Hospitals, University, Retrospective Studies, Informed Consent, Germany, Advance Directives, Tissue and Organ Procurement
- Published
- 2023
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8. Towards an automated data cleaning with deep learning in CRESST.
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Angloher G, Banik S, Bartolot D, Benato G, Bento A, Bertolini A, Breier R, Bucci C, Burkhart J, Canonica L, D'Addabbo A, Di Lorenzo S, Einfalt L, Erb A, Feilitzsch FV, Iachellini NF, Fichtinger S, Fuchs D, Fuss A, Garai A, Ghete VM, Gerster S, Gorla P, Guillaumon PV, Gupta S, Hauff D, Ješkovský M, Jochum J, Kaznacheeva M, Kinast A, Kluck H, Kraus H, Lackner M, Langenkämper A, Mancuso M, Marini L, Meyer L, Mokina V, Nilima A, Olmi M, Ortmann T, Pagliarone C, Pattavina L, Petricca F, Potzel W, Povinec P, Pröbst F, Pucci F, Reindl F, Rizvanovic D, Rothe J, Schäffner K, Schieck J, Schmiedmayer D, Schönert S, Schwertner C, Stahlberg M, Stodolsky L, Strandhagen C, Strauss R, Usherov I, Wagner F, Willers M, Zema V, and Waltenberger W
- Abstract
The CRESST experiment employs cryogenic calorimeters for the sensitive measurement of nuclear recoils induced by dark matter particles. The recorded signals need to undergo a careful cleaning process to avoid wrongly reconstructed recoil energies caused by pile-up and read-out artefacts. We frame this process as a time series classification task and propose to automate it with neural networks. With a data set of over one million labeled records from 68 detectors, recorded between 2013 and 2019 by CRESST, we test the capability of four commonly used neural network architectures to learn the data cleaning task. Our best performing model achieves a balanced accuracy of 0.932 on our test set. We show on an exemplary detector that about half of the wrongly predicted events are in fact wrongly labeled events, and a large share of the remaining ones have a context-dependent ground truth. We furthermore evaluate the recall and selectivity of our classifiers with simulated data. The results confirm that the trained classifiers are well suited for the data cleaning task., Competing Interests: Conflict of interestOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© The Author(s) 2023.)
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- 2023
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9. Binding free energies for the SAMPL8 CB8 "Drugs of Abuse" challenge from umbrella sampling combined with Hamiltonian replica exchange.
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Markthaler D, Kraus H, and Hansen N
- Subjects
- Imidazoles chemistry, Ligands, Protein Binding, Proteins chemistry, Retrospective Studies, Thermodynamics, Bridged-Ring Compounds chemistry, Molecular Dynamics Simulation
- Abstract
Umbrella sampling along a one-dimensional order parameter in combination with Hamiltonian replica exchange was employed to calculate the binding free energy of five guest molecules with known affinity to cucurbit[8]uril. A simple empirical approach correcting for the overestimation of the affinity by the GAFF force field was proposed and subsequently applied to the seven guest molecules of the "Drugs of Abuse" SAMPL8 challenge. Compared to the uncorrected binding free energies, the systematic error decreased but quantitative agreement with experiment was only reached for a few compounds. From a retrospective analysis a weak point of the correction term was identified., (© 2021. The Author(s).)
- Published
- 2022
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10. Al 2 O 3 co-doped with Cr 3+ and Mn 4+ , a dual-emitter probe for multimodal non-contact luminescence thermometry.
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Mykhaylyk VB, Kraus H, Bulyk LI, Lutsyuk I, Hreb V, Vasylechko L, Zhydachevskyy Y, Wagner A, and Suchocki A
- Abstract
Luminescence probes that facilitate multimodal non-contact measurements of temperature are of particular interest due to the possibility of cross-referencing results across different readout techniques. This intrinsic referencing is an essential addition that enhances accuracy and reliability of the technique. A further enhancement of sensor performance can be achieved by using two luminescent ions acting as independent emitters, thereby adding in-built redundancy to non-contact temperature sensing, using a single readout technique. In this study we combine both approaches by engineering a material with two luminescent ions that can be independently probed through different readout modes of non-contact temperature sensing. The approach was tested using Al
2 O3 co-doped with Cr3+ and Mn4+ , exhibiting sharp emission lines due to2 E →4 A2 transitions. The temperature sensing performance was examined by measuring three characteristics: temperature-induced changes of the intensity ratio of the emission lines, their spectral position, and the luminescence decay time constant. The processes responsible for the changes with temperature of the measured luminescence characteristics are discussed in terms of relevant models. By comparing temperature resolutions achievable by different modes of temperature sensing it is established that in Al2 O3 -Cr,Mn spectroscopic methods provide the best measurement accuracy over a broad temperature range. A temperature resolution better than ±2.8 K can be achieved by monitoring the luminescence intensity ratio (40-145 K) and the spectral shift of the R-line of Mn4+ (145-300 K range).- Published
- 2021
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11. Limits to Electrical Mobility in Lead-Halide Perovskite Semiconductors.
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Xia CQ, Peng J, Poncé S, Patel JB, Wright AD, Crothers TW, Uller Rothmann M, Borchert J, Milot RL, Kraus H, Lin Q, Giustino F, Herz LM, and Johnston MB
- Abstract
Semiconducting polycrystalline thin films are cheap to produce and can be deposited on flexible substrates, yet high-performance electronic devices usually utilize single-crystal semiconductors, owing to their superior charge-carrier mobilities and longer diffusion lengths. Here we show that the electrical performance of polycrystalline films of metal-halide perovskites (MHPs) approaches that of single crystals at room temperature. Combining temperature-dependent terahertz conductivity measurements and ab initio calculations we uncover a complete picture of the origins of charge-carrier scattering in single crystals and polycrystalline films of CH
3 NH3 PbI3 . We show that Fröhlich scattering of charge carriers with multiple phonon modes is the dominant mechanism limiting mobility, with grain-boundary scattering further reducing mobility in polycrystalline films. We reconcile the large discrepancy in charge-carrier diffusion lengths between single crystals and films by considering photon reabsorption. Thus, polycrystalline films of MHPs offer great promise for devices beyond solar cells, including light-emitting diodes and modulators.- Published
- 2021
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12. Multimodal Non-Contact Luminescence Thermometry with Cr-Doped Oxides.
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Mykhaylyk VB, Kraus H, Zhydachevskyy Y, Tsiumra V, Luchechko A, Wagner A, and Suchocki A
- Abstract
Luminescence methods for non-contact temperature monitoring have evolved through improvements of hardware and sensor materials. Future advances in this field rely on the development of multimodal sensing capabilities of temperature probes and extend the temperature range across which they operate. The family of Cr-doped oxides appears particularly promising and we review their luminescence characteristics in light of their application in non-contact measurements of temperature over the 5-300 K range. Multimodal sensing utilizes the intensity ratio of emission lines, their wavelength shift, and the scintillation decay time constant. We carried out systematic studies of the temperature-induced changes in the luminescence of the Cr
3+ -doped oxides Al2 O3 , Ga2 O3 , Y3 Al5 O12 , and YAlO3 . The mechanism responsible for the temperature-dependent luminescence characteristic is discussed in terms of relevant models. It is shown that the thermally-induced processes of particle exchange, governing the dynamics of Cr3+ ion excited state populations, require low activation energy. This then translates into tangible changes of a luminescence parameter with temperature. We compare different schemes of temperature sensing and demonstrate that Ga2 O3 -Cr is a promising material for non-contact measurements at cryogenic temperatures. A temperature resolution better than ±1 K can be achieved by monitoring the luminescence intensity ratio (40-140 K) and decay time constant (80-300 K range).- Published
- 2020
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13. Perdeuterated Conjugated Polymers for Ultralow-Frequency Magnetic Resonance of OLEDs.
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Milster S, Grünbaum T, Bange S, Kurrmann S, Kraus H, Stoltzfus DM, Leung AE, Darwish TA, Burn PL, Boehme C, and Lupton JM
- Abstract
The formation of excitons in OLEDs is spin dependent and can be controlled by electron-paramagnetic resonance, affecting device resistance and electroluminescence yield. We explore electrically detected magnetic resonance in the regime of very low magnetic fields (<1 mT). A pronounced feature emerges at zero field in addition to the conventional spin- 1 / 2 Zeeman resonance for which the Larmor frequency matches that of the incident radiation. By comparing a conventional π-conjugated polymer as the active material to a perdeuterated analogue, we demonstrate the interplay between the zero-field feature and local hyperfine fields. The zero-field peak results from a quasistatic magnetic-field effect of the RF radiation for periods comparable to the carrier-pair lifetime. Zeeman resonances are resolved down to 3.2 MHz, approximately twice the Larmor frequency of an electron in Earth's field. However, since reducing hyperfine fields sharpens the Zeeman peak at the cost of an increased zero-field peak, we suggest that this result may constitute a fundamental low-field limit of magnetic resonance in carrier-pair-based systems. OLEDs offer an alternative solid-state platform to investigate the radical-pair mechanism of magnetic-field effects in photochemical reactions, allowing models of biological magnetoreception to be tested by measuring spin decoherence directly in the time domain by pulsed experiments., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)
- Published
- 2020
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14. Bright and fast scintillations of an inorganic halide perovskite CsPbBr 3 crystal at cryogenic temperatures.
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Mykhaylyk VB, Kraus H, Kapustianyk V, Kim HJ, Mercere P, Rudko M, Da Silva P, Antonyak O, and Dendebera M
- Abstract
Highly efficient scintillation crystals with short decay times are indispensable for improving the performance of numerous detection and imaging instruments that use- X-rays, gamma-quanta, ionising particles or neutrons. Halide perovskites emerged recently as very promising materials for detection of ionising radiation that motivated further exploration of the materials. In this work, we report on excellent scintillation properties of CsPbBr
3 crystals when cooled to cryogenic temperatures. The temperature dependence of luminescence spectra, decay kinetics and light yield under excitation with X-rays and α-particles was investigated. It is shown that the observed changes of spectral and kinetic characteristics of the crystal with temperature can be consistently explained by radiative decay of free excitons, bound and trapped excitons as well as electron-hole pairs originating from their disintegration. It has been found that the crystal exhibits a fast decay time constant of 1 ns at 7 K. The scintillation light yield of CsPbBr3 at 7 K is assessed to be 50,000 ± 10,000 ph/MeV at excitation with 12 keV X-rays and 109,000 ± 22,000 ph/MeV at excitation with α-particles of241 Am. This finding places CsPbBr3 in an excellent position for the development of a new generation of cryogenic, efficient scintillation detectors with nanosecond response time, marking a step-change in opportunities for scintillator-based applications.- Published
- 2020
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15. OLEDs as models for bird magnetoception: detecting electron spin resonance in geomagnetic fields.
- Author
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Grünbaum T, Milster S, Kraus H, Ratzke W, Kurrmann S, Zeller V, Bange S, Boehme C, and Lupton JM
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- Electron Spin Resonance Spectroscopy, Fluorescence, Magnetic Fields, Models, Chemical, Quantum Theory
- Abstract
Certain species of living creatures are known to orientate themselves in the geomagnetic field. Given the small magnitude of approximately 48 μT, the underlying quantum mechanical phenomena are expected to exhibit coherence times in the microsecond regime. In this contribution, we show the sensitivity of organic light-emitting diodes (OLEDs) to magnetic fields far below Earth's magnetic field, suggesting that coherence times of the spins of charge-carrier pairs in these devices can be similarly long. By electron paramagnetic resonance (EPR) experiments, a lower bound for the coherence time can be assessed directly. Moreover, this technique offers the possibility to determine the distribution of hyperfine fields within the organic semiconductor layer. We extend this technique to a material system exhibiting both fluorescence and phosphorescence, demonstrating stable anticorrelation between optically detected magnetic resonance (ODMR) spectra in the singlet (fluorescence) and triplet (phosphorescence) channels. The experiments demonstrate the extreme sensitivity of OLEDs to both static as well as dynamic magnetic fields and suggest that coherent spin precession processes of coulombically bound electron-spin pairs may play a crucial role in the magnetoreceptive ability of living creatures.
- Published
- 2019
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16. Olefin Metathesis in Confined Geometries: A Biomimetic Approach toward Selective Macrocyclization.
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Ziegler F, Teske J, Elser I, Dyballa M, Frey W, Kraus H, Hansen N, Rybka J, Tallarek U, and Buchmeiser MR
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- Alkenes chemical synthesis, Biomimetics methods, Catalysis, Chemistry Techniques, Synthetic methods, Cyclization, Macrocyclic Compounds chemistry, Models, Molecular, Polymerization, Porosity, Ruthenium chemistry, Silicon Dioxide chemistry, Alkenes chemistry, Macrocyclic Compounds chemical synthesis
- Abstract
The synthesis of macrocycles is severely impeded by concomitant oligomer formation. Here, we present a biomimetic approach that utilizes spatial confinement to increase macrocyclization selectivity in the ring-closing metathesis of various dienes at elevated substrate concentration up to 25 mM using an olefin metathesis catalyst selectively immobilized inside ordered mesoporous silicas with defined pore diameters. By this approach, the ratio between macro(mono)cyclization (MMC) product and all undesired oligomerization products (O) resulting from acyclic diene metathesis polymerization was increased from 0.55, corresponding to 35% MMC product obtained with the homogeneous catalyst, up to 1.49, corresponding to 60% MMC product. A correlation between the MMC/O ratio and the substrate-to-pore-size ratio was successfully established. Modification of the inner pore surface with dimethoxydimethylsilane allowed fine-tuning the effective pore size and reversing surface polarity, which resulted in a further increase of the MMC/O ratio up to 2.2, corresponding to >68% MMC product. Molecular-level simulations in model pore geometries help to rationalize the complex interplay between spatial confinement, specific (substrate and product) interaction with the pore surface, and diffusive transport. These effects can be synergistically adjusted for optimum selectivity by suitable surface modification.
- Published
- 2019
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17. Megahertz non-contact luminescence decay time cryothermometry by means of ultrafast PbI 2 scintillator.
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Mykhaylyk VB, Kraus H, Bobb L, Gamernyk R, and Koronski K
- Abstract
Realtime in situ temperature monitoring in difficult experimental conditions or inaccessible environments is critical for many applications. Non-contact luminescence decay time thermometry is often the method of choice for such applications due to a favorable combination of sensitivity, accuracy and robustness. In this work, we demonstrate the feasibility of an ultrafast PbI
2 scintillator for temperature determination, using the time structure of X-ray radiation, produced by a synchrotron. The decay kinetics of the scintillations was measured over the 8-107 K temperature range using monochromatic pulsed X-ray excitation. It is found that lead iodide exhibits a very fast and intense scintillation response due to excitons and donor-acceptor pairs, with the fast decay component varying between 0.08 and 0.5 ns - a feature that can be readily exploited for temperature monitoring. The observed temperature dependence of the decay time is discussed in terms of two possible mechanisms of thermal quenching - transition over activation barrier and phonon-assisted escape. It is concluded that the latter provides a better fit to the experimental results and is consistent with the model of luminescence processes in PbI2 . We evaluated the sensitivity and estimated the accuracy of the temperature determination as ca. ±6 K at 107 K, improving to ±1.4 K at 8 K. The results of this study prove the feasibility of temperature monitoring, using ultrafast scintillation of PbI2 excited by X-ray pulses from a synchrotron, thus enabling non-contact in-situ cryothermometry with megahertz sampling rate.- Published
- 2019
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18. Geant4-based electromagnetic background model for the CRESST dark matter experiment.
- Author
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Abdelhameed AH, Angloher G, Bauer P, Bento A, Bertoldo E, Breier R, Bucci C, Canonica L, D'Addabbo A, Lorenzo SD, Erb A, Feilitzsch FV, Iachellini NF, Fichtinger S, Fuss A, Gorla P, Hauff D, Jes Kovský M, Jochum J, Kaizer J, Kinast A, Kluck H, Kraus H, Langenkämper A, Mancuso M, Mokina V, Mondragón E, Olmi M, Ortmann T, Pagliarone C, Palus Ová V, Pattavina L, Petricca F, Potzel W, Povinec P, Pröbst F, Reindl F, Rothe J, Schäffner K, Schieck J, Schipperges V, Schmiedmayer D, Schönert S, Schwertner C, Stahlberg M, Stodolsky L, Strandhagen C, Strauss R, Türkoğlu C, Usherov I, Willers M, Zema V, and Zeman J
- Abstract
The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) dark matter search experiment aims for the detection of dark matter particles via elastic scattering off nuclei in CaWO 4 crystals. To understand the CRESST electromagnetic background due to the bulk contamination in the employed materials, a model based on Monte Carlo simulations was developed using the Geant4 simulation toolkit. The results of the simulation are applied to the TUM40 detector module of CRESST-II phase 2. We are able to explain up to ( 68 ± 16 ) % of the electromagnetic background in the energy range between 1 and 40 keV ., (© The Author(s) 2019.)
- Published
- 2019
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19. Overcoming Convergence Issues in Free-Energy Calculations of Amide-to-Ester Mutations in the Pin1-WW Domain.
- Author
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Markthaler D, Kraus H, and Hansen N
- Subjects
- Amides chemistry, Amino Acid Sequence, Esters chemistry, Humans, Hydrogen Bonding, Mutation, NIMA-Interacting Peptidylprolyl Isomerase genetics, Protein Stability, Thermodynamics, WW Domains, Molecular Dynamics Simulation, NIMA-Interacting Peptidylprolyl Isomerase chemistry, Protein Folding
- Abstract
Relative folding free energies for a series of amide-to-ester mutations in the Pin1-WW domain are calculated using molecular dynamics simulations. Special focus is given to the identification and elimination of a simulation-related bias which was observed in previous work (Eichenberger et al. Biochim. Biophys. Acta 2015, 1850, 983) by comparing simulation results obtained with two different starting structures. Subtle local variations in the protein starting structure may lead to substantial deviations in the calculated free-energy changes as a consequence of differences in the sampled ϕ/ψ-dihedral angle distributions of the mutated residue. It is found that the combination of alchemical transformation with Hamiltonian replica exchange for enhanced sampling reduces the starting structure dependence considerably. Compared to previous work, the improved sampling of both the folded and unfolded states also improves the agreement between simulation and experiment.
- Published
- 2018
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20. The Effects of Doping Density and Temperature on the Optoelectronic Properties of Formamidinium Tin Triiodide Thin Films.
- Author
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Milot RL, Klug MT, Davies CL, Wang Z, Kraus H, Snaith HJ, Johnston MB, and Herz LM
- Abstract
Optoelectronic properties are unraveled for formamidinium tin triiodide (FASnI
3 ) thin films, whose background hole doping density is varied through SnF2 addition during film fabrication. Monomolecular charge-carrier recombination exhibits both a dopant-mediated part that grows linearly with hole doping density and remnant contributions that remain under tin-enriched processing conditions. At hole densities near 1020 cm-3 , a strong Burstein-Moss effect increases absorption onset energies by ≈300 meV beyond the bandgap energy of undoped FASnI3 (shown to be 1.2 eV at 5 K and 1.35 eV at room temperature). At very high doping densities (1020 cm-3 ), temperature-dependent measurements indicate that the effective charge-carrier mobility is suppressed through scattering with ionized dopants. Once the background hole concentration is nearer 1019 cm-3 and below, the charge-carrier mobility increases with decreasing temperature according to ≈T-1.2 , suggesting that it is limited mostly by intrinsic interactions with lattice vibrations. For the lowest doping concentration of 7.2 × 1018 cm-3 , charge-carrier mobilities reach a value of 67 cm2 V-1 s-1 at room temperature and 470 cm2 V-1 s-1 at 50 K. Intraexcitonic transitions observed in the THz-frequency photoconductivity spectra at 5 K reveal an exciton binding energy of only 3.1 meV for FASnI3 , in agreement with the low bandgap energy exhibited by this perovskite., (© 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
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21. Impact of the Organic Cation on the Optoelectronic Properties of Formamidinium Lead Triiodide.
- Author
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Davies CL, Borchert J, Xia CQ, Milot RL, Kraus H, Johnston MB, and Herz LM
- Abstract
Metal halide perovskites have proven to be excellent light-harvesting materials in photovoltaic devices whose efficiencies are rapidly improving. Here, we examine the temperature-dependent photon absorption, exciton binding energy, and band gap of FAPbI
3 (thin film) and find remarkably different behavior across the β-γ phase transition compared with MAPbI3 . While MAPbI3 has shown abrupt changes in the band gap and exciton binding energy, values for FAPbI3 vary smoothly over a range of 100-160 K in accordance with a more gradual transition. In addition, we find that the charge-carrier mobility in FAPbI3 exhibits a clear T-0.5 trend with temperature, in excellent agreement with theoretical predictions that assume electron-phonon interactions to be governed by the Fröhlich mechanism but in contrast to the T-1.5 dependence previously observed for MAPbI3 . Finally, we directly observe intraexcitonic transitions in FAPbI3 at low temperature, from which we determine a low exciton binding energy of only 5.3 meV at 10 K.- Published
- 2018
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22. A new herbicidal site of action: Cinmethylin binds to acyl-ACP thioesterase and inhibits plant fatty acid biosynthesis.
- Author
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Campe R, Hollenbach E, Kämmerer L, Hendriks J, Höffken HW, Kraus H, Lerchl J, Mietzner T, Tresch S, Witschel M, and Hutzler J
- Subjects
- Arabidopsis metabolism, Araceae metabolism, Biological Transport, Crystallography, X-Ray, Endoplasmic Reticulum metabolism, Fatty Acid Synthesis Inhibitors metabolism, Fatty Acid Synthesis Inhibitors pharmacology, Fatty Acids biosynthesis, Fluorescence, Gas Chromatography-Mass Spectrometry, Herbicide Resistance, Herbicides pharmacology, Principal Component Analysis, Protein Conformation, Thiolester Hydrolases chemistry, Arabidopsis drug effects, Araceae drug effects, Fatty Acids antagonists & inhibitors, Herbicides metabolism, Plant Proteins metabolism, Thiolester Hydrolases metabolism
- Abstract
The prevalent occurrence of herbicide resistant weeds increases the necessity for new site of action herbicides for effective control as well as to relax selection pressure on the known sites of action. As a consequence, interest increased in the unexploited molecule cinmethylin as a new solution for the control of weedy grasses in cereals. Therefore, the mechanism of action of cinmethylin was reevaluated. We applied the chemoproteomic approach cellular Target Profiling™ from Evotec to identify the cinmethylin target in Lemna paucicostata protein extracts. We found three potential targets belonging to the same protein family of fatty acid thioesterases (FAT) to bind to cinmethylin with high affinity. Binding of cinmethylin to FAT proteins from Lemna and Arabidopsis was confirmed by fluorescence-based thermal shift assay. The plastid localized enzyme FAT plays a crucial role in plant lipid biosynthesis, by mediating the release of fatty acids (FA) from its acyl carrier protein (ACP) which is necessary for FA export to the endoplasmic reticulum. GC-MS analysis of free FA composition in Lemna extracts revealed strong reduction of unsaturated C18 as well as saturated C14, and C16 FAs upon treatment with cinmethylin, indicating that FA release for subsequent lipid biosynthesis is the primary target of cinmethylin. Lipid biosynthesis is a prominent target of different herbicide classes. To assess whether FAT inhibition constitutes a new mechanism of action within this complex pathway, we compared physiological effects of cinmethylin to different ACCase and VLCFA synthesis inhibitors and identified characteristic differences in plant symptomology and free FA composition upon treatment with the three herbicide classes. Also, principal component analysis of total metabolic profiling of treated Lemna plants showed strong differences in overall metabolic changes after cinmethylin, ACCase or VLCFA inhibitor treatments. Our results identified and confirmed FAT as the cinmethylin target and validate FAT inhibition as a new site of action different from other lipid biosynthesis inhibitor classes., (Copyright © 2018 BASF SE. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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23. Human NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome activity is regulated by and potentially targetable through Bruton tyrosine kinase.
- Author
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Liu X, Pichulik T, Wolz OO, Dang TM, Stutz A, Dillen C, Delmiro Garcia M, Kraus H, Dickhöfer S, Daiber E, Münzenmayer L, Wahl S, Rieber N, Kümmerle-Deschner J, Yazdi A, Franz-Wachtel M, Macek B, Radsak M, Vogel S, Schulte B, Walz JS, Hartl D, Latz E, Stilgenbauer S, Grimbacher B, Miller L, Brunner C, Wolz C, and Weber ANR
- Subjects
- Adaptive Immunity, Adaptor Proteins, Signal Transducing, Agammaglobulinaemia Tyrosine Kinase, Animals, Apoptosis Regulatory Proteins, Bacterial Proteins immunology, Cells, Cultured, Humans, Immunity, Innate, Leukocidins immunology, Mice, Mice, Inbred C57BL, Mice, Knockout, Molecular Targeted Therapy, NLR Proteins, Nigericin immunology, Protein-Tyrosine Kinases genetics, Proteomics, Pyrin Domain genetics, Receptors, Cytoplasmic and Nuclear metabolism, Lamin B Receptor, Agammaglobulinemia genetics, Cryopyrin-Associated Periodic Syndromes genetics, Genetic Diseases, X-Linked genetics, Inflammasomes metabolism, NLR Family, Pyrin Domain-Containing 3 Protein metabolism, Protein-Tyrosine Kinases metabolism, Staphylococcal Infections immunology, Staphylococcus aureus immunology
- Abstract
Background: The Nod-like receptor NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) and Bruton tyrosine kinase (BTK) are protagonists in innate and adaptive immunity, respectively. NLRP3 senses exogenous and endogenous insults, leading to inflammasome activation, which occurs spontaneously in patients with Muckle-Wells syndrome; BTK mutations cause the genetic immunodeficiency X-linked agammaglobulinemia (XLA). However, to date, few proteins that regulate NLRP3 inflammasome activity in human primary immune cells have been identified, and clinically promising pharmacologic targeting strategies remain elusive., Objective: We sought to identify novel regulators of the NLRP3 inflammasome in human cells with a view to exploring interference with inflammasome activity at the level of such regulators., Methods: After proteome-wide phosphoproteomics, the identified novel regulator BTK was studied in human and murine cells by using pharmacologic and genetic BTK ablation., Results: Here we show that BTK is a critical regulator of NLRP3 inflammasome activation: pharmacologic (using the US Food and Drug Administration-approved inhibitor ibrutinib) and genetic (in patients with XLA and Btk knockout mice) BTK ablation in primary immune cells led to reduced IL-1β processing and secretion in response to nigericin and the Staphylococcus aureus toxin leukocidin AB (LukAB). BTK affected apoptosis-associated speck-like protein containing a CARD (ASC) speck formation and caspase-1 cleavage and interacted with NLRP3 and ASC. S aureus infection control in vivo and IL-1β release from cells of patients with Muckle-Wells syndrome were impaired by ibrutinib. Notably, IL-1β processing and release from immune cells isolated from patients with cancer receiving ibrutinib therapy were reduced., Conclusion: Our data suggest that XLA might result in part from genetic inflammasome deficiency and that NLRP3 inflammasome-linked inflammation could potentially be targeted pharmacologically through BTK., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2017
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24. Three-Dimensional Proton Beam Writing of Optically Active Coherent Vacancy Spins in Silicon Carbide.
- Author
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Kraus H, Simin D, Kasper C, Suda Y, Kawabata S, Kada W, Honda T, Hijikata Y, Ohshima T, Dyakonov V, and Astakhov GV
- Abstract
Constructing quantum devices comprises various challenging tasks, especially when concerning their nanoscale geometry. For quantum color centers, the traditional approach is to fabricate the device structure after the nondeterministic placement of the centers. Reversing this approach, we present the controlled generation of quantum centers in silicon carbide (SiC) by focused proton beam in a noncomplex manner without need for pre- or postirradiation treatment. The generation depth and resolution can be predicted by matching the proton energy to the material's stopping power, and the amount of quantum centers at one specific sample volume is tunable from ensembles of millions to discernible single photon emitters. We identify the generated centers as silicon vacancies through their characteristic magnetic resonance signatures and demonstrate that they possess a long spin-echo coherence time of 42 ± 20 μs at room temperature. Our approach hence enables the fabrication of quantum hybrid nanodevices based on SiC platform, where spin centers are integrated into p-i-n diodes, photonic cavities, and mechanical resonators.
- Published
- 2017
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25. Non-contact luminescence lifetime cryothermometry for macromolecular crystallography.
- Author
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Mykhaylyk VB, Wagner A, and Kraus H
- Abstract
Temperature is a very important parameter when aiming to minimize radiation damage to biological samples during experiments that utilize intense ionizing radiation. A novel technique for remote, non-contact, in situ monitoring of the protein crystal temperature has been developed for the new I23 beamline at the Diamond Light Source, a facility dedicated to macromolecular crystallography (MX) with long-wavelength X-rays. The temperature is derived from the temperature-dependent decay time constant of luminescence from a minuscule scintillation sensor (<0.05 mm
3 ) located in very close proximity to the sample under test. In this work the underlying principle of cryogenic luminescence lifetime thermometry is presented, the features of the detection method and the choice of temperature sensor are discussed, and it is demonstrated how the temperature monitoring system was integrated within the viewing system of the endstation used for the visualization of protein crystals. The thermometry system was characterized using a Bi4 Ge3 O12 crystal scintillator that exhibits good responsivity of the decay time constant as a function of temperature over a wide range (8-270 K). The scintillation sensor was calibrated and the uncertainty of the temperature measurements over the primary operation temperature range of the beamline (30-150 K) was assessed to be ±1.6 K. It has been shown that the temperature of the sample holder, measured using the luminescence sensor, agrees well with the expected value. The technique was applied to characterize the thermal performance of different sample mounts that have been used in MX experiments at the I23 beamline. The thickness of the mount is shown to have the greatest impact upon the temperature distribution across the sample mount. Altogether, these tests and findings demonstrate the usefulness of the thermometry system in highlighting the challenges that remain to be addressed for the in-vacuum MX experiment to become a reliable and indispensable tool for structural biology.- Published
- 2017
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26. Development of 100 Mo -containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search.
- Author
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Armengaud E, Augier C, Barabash AS, Beeman JW, Bekker TB, Bellini F, Benoît A, Bergé L, Bergmann T, Billard J, Boiko RS, Broniatowski A, Brudanin V, Camus P, Capelli S, Cardani L, Casali N, Cazes A, Chapellier M, Charlieux F, Chernyak DM, de Combarieu M, Coron N, Danevich FA, Dafinei I, Jesus M, Devoyon L, Domizio SD, Dumoulin L, Eitel K, Enss C, Ferroni F, Fleischmann A, Foerster N, Gascon J, Gastaldo L, Gironi L, Giuliani A, Grigorieva VD, Gros M, Hehn L, Hervé S, Humbert V, Ivannikova NV, Ivanov IM, Jin Y, Juillard A, Kleifges M, Kobychev VV, Konovalov SI, Koskas F, Kozlov V, Kraus H, Kudryavtsev VA, Laubenstein M, Sueur HL, Loidl M, Magnier P, Makarov EP, Mancuso M, de Marcillac P, Marnieros S, Marrache-Kikuchi C, Nagorny S, Navick XF, Nikolaichuk MO, Nones C, Novati V, Olivieri E, Pagnanini L, Pari P, Pattavina L, Pavan M, Paul B, Penichot Y, Pessina G, Piperno G, Pirro S, Plantevin O, Poda DV, Queguiner E, Redon T, Rodrigues M, Rozov S, Rusconi C, Sanglard V, Schäffner K, Scorza S, Shlegel VN, Siebenborn B, Strazzer O, Tcherniakhovski D, Tomei C, Tretyak VI, Umatov VI, Vagneron L, Vasiliev YV, Velázquez M, Vignati M, Weber M, Yakushev E, and Zolotarova AS
- Abstract
This paper reports on the development of a technology involving 100 Mo -enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next-generation bolometric experiment to search for neutrinoless double-beta decay. Large mass ( ∼ 1 kg ), high optical quality, radiopure 100 Mo -containing zinc and lithium molybdate crystals have been produced and used to develop high performance single detector modules based on 0.2-0.4 kg scintillating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q -value of the double-beta transition of 100 Mo (3034 keV) is 4-6 keV FWHM. The rejection of the α -induced dominant background above 2.6 MeV is better than 8 σ . Less than 10 μ Bq/kg activity of 232 Th ( 228 Th ) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo -enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg × d exposure: the two neutrino double-beta decay half-life of 100 Mo has been measured with the up-to-date highest accuracy as T 1 / 2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 10 18 years . Both crystallization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100 Mo ., (© The Author(s) 2017.)
- Published
- 2017
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27. New pathways in the evaluation of programmes for men who perpetrate violence against their female partners.
- Author
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Wojnicka K, Scambor C, and Kraus H
- Subjects
- Crime Victims rehabilitation, Cross-Cultural Comparison, Domestic Violence legislation & jurisprudence, Domestic Violence psychology, Europe, Female, Humans, Male, Program Evaluation, Qualitative Research, Rehabilitation legislation & jurisprudence, Rehabilitation organization & administration, Social Support, Crime Victims psychology, Domestic Violence prevention & control, Rehabilitation methods
- Abstract
Today, evaluation research in the field of intervention programmes for men who perpetrate violence against their female partners still makes a fragmentary impression. Across Europe various evaluation studies have been performed. However, the methodologies applied are too heterogeneous to allow the combination of the results in a meta-analytical way. In this paper we propose a future pathway for organising outcome evaluation studies of domestic violence perpetrator programmes in community settings, so that today's problems in this field can be overcome. In a pragmatic framework that acknowledges the limited pre-conditions for evaluation studies in the area of domestic violence perpetrator programmes as it is today, feasible approaches for outcome evaluation are outlined, with recent developments in the field taken as starting points. The framework for organising future evaluation studies of work with perpetrators of domestic violence is presented together with a strategy to promote this framework. International networks of practitioners and researchers play a central role in this strategy through upskilling the area of practical work, preparing the ground for evaluation research and improving cooperation between practitioners and researchers. This paper is based on the results of the European funded project IMPACT (under the Daphne-III-funding programme of the European Commission)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
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28. Limits on Momentum-Dependent Asymmetric Dark Matter with CRESST-II.
- Author
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Angloher G, Bento A, Bucci C, Canonica L, Defay X, Erb A, Feilitzsch FV, Ferreiro Iachellini N, Gorla P, Gütlein A, Hauff D, Jochum J, Kiefer M, Kluck H, Kraus H, Lanfranchi JC, Loebell J, Münster A, Pagliarone C, Petricca F, Potzel W, Pröbst F, Reindl F, Schäffner K, Schieck J, Schönert S, Seidel W, Stodolsky L, Strandhagen C, Strauss R, Tanzke A, Trinh Thi HH, Türkoğlu C, Uffinger M, Ulrich A, Usherov I, Wawoczny S, Willers M, Wüstrich M, and Zöller A
- Abstract
The usual assumption in direct dark matter searches is to consider only the spin-dependent or spin-independent scattering of dark matter particles. However, especially in models with light dark matter particles O(GeV/c^{2}), operators which carry additional powers of the momentum transfer q^{2} can become dominant. One such model based on asymmetric dark matter has been invoked to overcome discrepancies in helioseismology and an indication was found for a particle with a preferred mass of 3 GeV/c^{2} and a cross section of 10^{-37} cm^{2}. Recent data from the CRESST-II experiment, which uses cryogenic detectors based on CaWO_{4} to search for nuclear recoils induced by dark matter particles, are used to constrain these momentum-dependent models. The low energy threshold of 307 eV for nuclear recoils of the detector used, allows us to rule out the proposed best fit value above.
- Published
- 2016
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29. Analysis of Triplet Exciton Loss Pathways in PTB7:PC71BM Bulk Heterojunction Solar Cells.
- Author
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Kraus H, Heiber MC, Väth S, Kern J, Deibel C, Sperlich A, and Dyakonov V
- Abstract
A strategy for increasing the conversion efficiency of organic photovoltaics has been to increase the VOC by tuning the energy levels of donor and acceptor components. However, this opens up a new loss pathway from an interfacial charge transfer state to a triplet exciton (TE) state called electron back transfer (EBT), which is detrimental to device performance. To test this hypothesis, we study triplet formation in the high performing PTB7:PC71BM blend system and determine the impact of the morphology-optimizing additive 1,8-diiodoctane (DIO). Using photoluminescence and spin-sensitive optically detected magnetic resonance (ODMR) measurements at low temperature, we find that TEs form on PC71BM via intersystem crossing from singlet excitons and on PTB7 via EBT mechanism. For DIO blends with smaller fullerene domains, an increased density of PTB7 TEs is observed. The EBT process is found to be significant only at very low temperature. At 300 K, no triplets are detected via ODMR, and electrically detected magnetic resonance on optimized solar cells indicates that TEs are only present on the fullerenes. We conclude that in PTB7:PC71BM devices, TE formation via EBT is impacted by fullerene domain size at low temperature, but at room temperature, EBT does not represent a dominant loss pathway.
- Published
- 2016
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30. Sphingosine-1-phosphate receptors control B-cell migration through signaling components associated with primary immunodeficiencies, chronic lymphocytic leukemia, and multiple sclerosis.
- Author
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Sic H, Kraus H, Madl J, Flittner KA, von Münchow AL, Pieper K, Rizzi M, Kienzler AK, Ayata K, Rauer S, Kleuser B, Salzer U, Burger M, Zirlik K, Lougaris V, Plebani A, Römer W, Loeffler C, Scaramuzza S, Villa A, Noguchi E, Grimbacher B, and Eibel H
- Subjects
- Adaptor Proteins, Signal Transducing genetics, Adaptor Proteins, Signal Transducing immunology, Adaptor Proteins, Signal Transducing metabolism, Agammaglobulinaemia Tyrosine Kinase, Antigens, CD genetics, Antigens, CD immunology, Antigens, CD metabolism, Antigens, Differentiation, T-Lymphocyte genetics, Antigens, Differentiation, T-Lymphocyte immunology, Antigens, Differentiation, T-Lymphocyte metabolism, Arrestins genetics, Arrestins immunology, Arrestins metabolism, B-Lymphocyte Subsets immunology, B-Lymphocyte Subsets pathology, Cell Line, Cell Movement, Common Variable Immunodeficiency genetics, Common Variable Immunodeficiency immunology, Common Variable Immunodeficiency pathology, Gene Expression Regulation, Guanine Nucleotide Exchange Factors genetics, Guanine Nucleotide Exchange Factors immunology, Guanine Nucleotide Exchange Factors metabolism, Humans, Lectins, C-Type genetics, Lectins, C-Type immunology, Lectins, C-Type metabolism, Leukemia, Lymphocytic, Chronic, B-Cell genetics, Leukemia, Lymphocytic, Chronic, B-Cell immunology, Leukemia, Lymphocytic, Chronic, B-Cell pathology, Multiple Sclerosis genetics, Multiple Sclerosis immunology, Multiple Sclerosis pathology, Primary Cell Culture, Protein Isoforms genetics, Protein Isoforms immunology, Protein Isoforms metabolism, Protein-Tyrosine Kinases genetics, Protein-Tyrosine Kinases immunology, Protein-Tyrosine Kinases metabolism, Receptors, Lysosphingolipid genetics, Receptors, Lysosphingolipid immunology, Signal Transduction, Time-Lapse Imaging, Wiskott-Aldrich Syndrome Protein genetics, Wiskott-Aldrich Syndrome Protein immunology, Wiskott-Aldrich Syndrome Protein metabolism, beta-Arrestin 2, beta-Arrestins, B-Lymphocyte Subsets metabolism, Common Variable Immunodeficiency metabolism, Leukemia, Lymphocytic, Chronic, B-Cell metabolism, Multiple Sclerosis metabolism, Receptors, Lysosphingolipid metabolism
- Abstract
Background: Five different G protein-coupled sphingosine-1-phosphate (S1P) receptors (S1P1-S1P5) regulate a variety of physiologic and pathophysiologic processes, including lymphocyte circulation, multiple sclerosis (MS), and cancer. Although B-lymphocyte circulation plays an important role in these processes and is essential for normal immune responses, little is known about S1P receptors in human B cells., Objective: To explore their function and signaling, we studied B-cell lines and primary B cells from control subjects, patients with leukemia, patients with S1P receptor inhibitor-treated MS, and patients with primary immunodeficiencies., Methods: S1P receptor expression was analyzed by using multicolor immunofluorescence microscopy and quantitative PCR. Transwell assays were used to study cell migration. S1P receptor internalization was visualized by means of time-lapse imaging with fluorescent S1P receptor fusion proteins expressed by using lentiviral gene transfer. B-lymphocyte subsets were characterized by means of flow cytometry and immunofluorescence microscopy., Results: Showing that different B-cell populations express different combinations of S1P receptors, we found that S1P1 promotes migration, whereas S1P4 modulates and S1P2 inhibits S1P1 signals. Expression of CD69 in activated B lymphocytes and B cells from patients with chronic lymphocytic leukemia inhibited S1P-induced migration. Studying B-cell lines, normal B lymphocytes, and B cells from patients with primary immunodeficiencies, we identified Bruton tyrosine kinase, β-arrestin 2, LPS-responsive beige-like anchor protein, dedicator of cytokinesis 8, and Wiskott-Aldrich syndrome protein as critical signaling components downstream of S1P1., Conclusion: Thus S1P receptor signaling regulates human B-cell circulation and might be a factor contributing to the pathology of MS, chronic lymphocytic leukemia, and primary immunodeficiencies., (Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)
- Published
- 2014
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31. Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide.
- Author
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Kraus H, Soltamov VA, Fuchs F, Simin D, Sperlich A, Baranov PG, Astakhov GV, and Dyakonov V
- Subjects
- Biosensing Techniques, Electron Spin Resonance Spectroscopy, Magnetic Fields, Magnetometry, Nanotechnology, Quantum Theory, Temperature, Carbon Compounds, Inorganic chemistry, Silicon Compounds chemistry
- Abstract
Quantum systems can provide outstanding performance in various sensing applications, ranging from bioscience to nanotechnology. Atomic-scale defects in silicon carbide are very attractive in this respect because of the technological advantages of this material and favorable optical and radio frequency spectral ranges to control these defects. We identified several, separately addressable spin-3/2 centers in the same silicon carbide crystal, which are immune to nonaxial strain fluctuations. Some of them are characterized by nearly temperature independent axial crystal fields, making these centers very attractive for vector magnetometry. Contrarily, the zero-field splitting of another center exhibits a giant thermal shift of -1.1 MHz/K at room temperature, which can be used for thermometry applications. We also discuss a synchronized composite clock exploiting spin centers with different thermal response.
- Published
- 2014
- Full Text
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32. In-house coordination for organ donation--single-center experience in a pilot project in Germany (2006 to 2013).
- Author
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Kaiser GM, Wirges U, Becker S, Baier C, Radunz S, Kraus H, and Paul A
- Subjects
- Germany, Humans, Pilot Projects, Reproducibility of Results, Retrospective Studies, Brain Death diagnosis, Brain Injuries pathology, Tissue Donors statistics & numerical data, Tissue and Organ Procurement organization & administration
- Abstract
A challenge for solid organ transplantation in Germany is the shortage of organs. In an effort to increase donation rates, some federal states mandated hospitals to install transplantation officers to coordinate, evaluate, and enhance the donation and transplantation processes. In 2009 the German Foundation for Organ Transplantation (DSO) implemented the In-House Coordination Project, which includes retrospective, quarterly, information technology-based case analyses of all deceased patients with primary or secondary brain injury in regard to the organ donation process in maximum care hospitals. From 2006 to 2008 an analysis of potential organ donors was performed in our hospital using a time-consuming, complex method using questionnaires, hand-written patient files, and the hospital IT documentation system (standard method). Analyses in the In-House Coordination Project are instead carried out by a proprietary semiautomated IT tool called Transplant Check, which uses easily accessible standard data records of the hospital controlling and accounting unit. The aim of our study was to compare the results of the standard method and Transplant Check in detecting and evaluating potential donors. To do so, the same period of time (2006 to 2008) was re-evaluated using the IT tool. Transplant Check was able to record significantly more patients who fulfilled the criteria for inclusion than the standard method (641 vs 424). The methods displayed a wide overlap, apart from 22 patients who were only recorded by the standard method. In these cases, the accompanying brain injury diagnosis was not recorded in the controlling and accounting unit data records due to little relative clinical significance. None of the 22 patients fulfilled the criteria for brain death. In summary, Transplant Check is an easy-to-use, reliable, and valid tool for evaluating donor potential in a maximum care hospital. Therefore from 2010 on, analyses were performed exclusively with Transplant Check at our university hospital., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
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33. Hypomorphic homozygous mutations in phosphoglucomutase 3 (PGM3) impair immunity and increase serum IgE levels.
- Author
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Sassi A, Lazaroski S, Wu G, Haslam SM, Fliegauf M, Mellouli F, Patiroglu T, Unal E, Ozdemir MA, Jouhadi Z, Khadir K, Ben-Khemis L, Ben-Ali M, Ben-Mustapha I, Borchani L, Pfeifer D, Jakob T, Khemiri M, Asplund AC, Gustafsson MO, Lundin KE, Falk-Sörqvist E, Moens LN, Gungor HE, Engelhardt KR, Dziadzio M, Stauss H, Fleckenstein B, Meier R, Prayitno K, Maul-Pavicic A, Schaffer S, Rakhmanov M, Henneke P, Kraus H, Eibel H, Kölsch U, Nadifi S, Nilsson M, Bejaoui M, Schäffer AA, Smith CI, Dell A, Barbouche MR, and Grimbacher B
- Subjects
- Adult, Amino Acid Substitution, Cell Proliferation, Child, Chromosomes, Human, Pair 6 metabolism, Female, Genetic Diseases, Inborn enzymology, Genetic Diseases, Inborn immunology, Genetic Linkage, Glycosylation, Humans, Infant, Job Syndrome enzymology, Job Syndrome immunology, Male, Phosphoglucomutase immunology, Phosphoglucomutase metabolism, T-Lymphocytes enzymology, T-Lymphocytes immunology, Tunisia, Chromosomes, Human, Pair 6 genetics, Genetic Diseases, Inborn genetics, Homozygote, Immunity genetics, Immunoglobulin E, Job Syndrome genetics, Mutation, Missense, Phosphoglucomutase genetics
- Abstract
Background: Recurrent bacterial and fungal infections, eczema, and increased serum IgE levels characterize patients with the hyper-IgE syndrome (HIES). Known genetic causes for HIES are mutations in signal transducer and activator of transcription 3 (STAT3) and dedicator of cytokinesis 8 (DOCK8), which are involved in signal transduction pathways. However, glycosylation defects have not been described in patients with HIES. One crucial enzyme in the glycosylation pathway is phosphoglucomutase 3 (PGM3), which catalyzes a key step in the synthesis of uridine diphosphate N-acetylglucosamine, which is required for the biosynthesis of N-glycans., Objective: We sought to elucidate the genetic cause in patients with HIES who do not carry mutations in STAT3 or DOCK8., Methods: After establishing a linkage interval by means of SNPchip genotyping and homozygosity mapping in 2 families with HIES from Tunisia, mutational analysis was performed with selector-based, high-throughput sequencing. Protein expression was analyzed by means of Western blotting, and glycosylation was profiled by using mass spectrometry., Results: Mutational analysis of candidate genes in an 11.9-Mb linkage region on chromosome 6 shared by 2 multiplex families identified 2 homozygous mutations in PGM3 that segregated with disease status and followed recessive inheritance. The mutations predict amino acid changes in PGM3 (p.Glu340del and p.Leu83Ser). A third homozygous mutation (p.Asp502Tyr) and the p.Leu83Ser variant were identified in 2 other affected families, respectively. These hypomorphic mutations have an effect on the biosynthetic reactions involving uridine diphosphate N-acetylglucosamine. Glycomic analysis revealed an aberrant glycosylation pattern in leukocytes demonstrated by a reduced level of tri-antennary and tetra-antennary N-glycans. T-cell proliferation and differentiation were impaired in patients. Most patients had developmental delay, and many had psychomotor retardation., Conclusion: Impairment of PGM3 function leads to a novel primary (inborn) error of development and immunity because biallelic hypomorphic mutations are associated with impaired glycosylation and a hyper-IgE-like phenotype., (Published by Mosby, Inc.)
- Published
- 2014
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34. B cell biology: an overview.
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Eibel H, Kraus H, Sic H, Kienzler AK, and Rizzi M
- Subjects
- Animals, Antigens immunology, B-Lymphocytes cytology, Cell Differentiation immunology, Cell Survival, Humans, Immunologic Memory, Transcription Factors immunology, B-Lymphocytes immunology
- Abstract
In this review we summarize recent insights into the development of human B cells primarily by studying immunodeficiencies. Development and differentiation of B cells can be considered as a paradigm for many other developmental processes in cell biology. However, it differs from the development of many other cell types by phases of extremely rapid cell division and by defined series of somatic recombination and mutation events required to assemble and refine the B cell antigen receptors. Both somatic DNA alteration and proliferation phases take place in defined sites but in different organs. Thus, cell migration and timely arrival at defined sites are additional features of B cell development. By comparing experimental mouse models with insights gained from studying defined genetic defects leading to primary immunodeficiencies and hypogammaglobulinemia, we address important features that are characteristic for human B cells. We also summarize recent advances made by developing improved in vitro and in vivo systems allowing the development of human B cells from hematopoietic stem cells. Combined with genetic and functional studies of immunodeficiencies, these models will contribute not only to a better understanding of disease affecting the B lymphocyte compartment, but also to designing better and safer novel B cell-targeted therapies in autoimmunity and allergy.
- Published
- 2014
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- View/download PDF
35. A common single nucleotide polymorphism impairs B-cell activating factor receptor's multimerization, contributing to common variable immunodeficiency.
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Pieper K, Rizzi M, Speletas M, Smulski CR, Sic H, Kraus H, Salzer U, Fiala GJ, Schamel WW, Lougaris V, Plebani A, Hammarstrom L, Recher M, Germenis AE, Grimbacher B, Warnatz K, Rolink AG, Schneider P, Notarangelo LD, and Eibel H
- Subjects
- B-Cell Activating Factor metabolism, Common Variable Immunodeficiency diagnosis, Common Variable Immunodeficiency metabolism, Humans, Receptors, Interleukin-4 metabolism, Common Variable Immunodeficiency genetics, Genetic Predisposition to Disease, Polymorphism, Single Nucleotide, Protein Multimerization, Receptors, Interleukin-4 chemistry, Receptors, Interleukin-4 genetics
- Published
- 2014
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- View/download PDF
36. A feeder-free differentiation system identifies autonomously proliferating B cell precursors in human bone marrow.
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Kraus H, Kaiser S, Aumann K, Bönelt P, Salzer U, Vestweber D, Erlacher M, Kunze M, Burger M, Pieper K, Sic H, Rolink A, Eibel H, and Rizzi M
- Subjects
- Adult, Animals, Bone Marrow, Cell Division, Cell Lineage, Cells, Cultured, Coculture Techniques, DNA-Binding Proteins deficiency, Fetal Blood cytology, Graft Survival, Hematopoietic Stem Cells drug effects, Heterografts, Homeostasis, Humans, Immunoglobulin M biosynthesis, Immunophenotyping, Interleukin-7 pharmacology, Lymphopoiesis drug effects, Mice, Radiation Chimera, Receptors, Interleukin-2 deficiency, Time Factors, Young Adult, B-Lymphocytes cytology, Cell Culture Techniques methods, Hematopoietic Stem Cells cytology
- Abstract
The peripheral B cell compartment is maintained by homeostatic proliferation and through replenishment by bone marrow precursors. Because hematopoietic stem cells cycle at a slow rate, replenishment must involve replication of precursor B cells. To study proliferation of early human B cell progenitors, we established a feeder cell-free in vitro system allowing the development of B cells from CD34(+) hematopoietic stem cells up to the stage of immature IgM(+) B cells. We found that pro-B and pre-B cells generated in vitro can proliferate autonomously and persist up to 7 wk in culture in the absence of signals induced by exogenously added cytokines. Nevertheless, addition of IL-7 enhanced pre-B cell expansion and inhibited maturation into IgM(+) B cells. The B cell precursor subsets replicating in vitro were highly similar to the bone marrow B cell precursors cycling in vivo. The autonomous proliferation of B cell precursor subsets in vitro and their long-term persistence implies that proliferation during pro-B and pre-B cell stages plays an important role in the homeostasis of the peripheral B cell compartment. Our in vitro culture can be used to study defects in B cell development or in reconstitution of the B cell pool after depletion and chemotherapy.
- Published
- 2014
- Full Text
- View/download PDF
37. Multiple reduction of 2,5-bis(borolyl)thiophene: isolation of a negative bipolaron by comproportionation.
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Braunschweig H, Dyakonov V, Engels B, Falk Z, Hörl C, Klein JH, Kramer T, Kraus H, Krummenacher I, Lambert C, and Walter C
- Subjects
- Anions chemistry, Crystallography, X-Ray, Oxidation-Reduction, Boron Compounds chemistry, Thiophenes chemistry
- Abstract
The 2,5-bis(borolyl)thiophene 2, a conjugated acceptor-π-acceptor system, can be reduced to the monoradical anion [2](.-) , the dianion [2](2-) , and the tetraanion [2](4-) . The dianion [2](2-) was also prepared by a comproportionation reaction and features an absorption maximum in the near-IR region (λmax =800 nm), which is characteristic of a bipolaron with a quinoidal structure., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2013
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38. Resonant addressing and manipulation of silicon vacancy qubits in silicon carbide.
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Riedel D, Fuchs F, Kraus H, Väth S, Sperlich A, Dyakonov V, Soltamova AA, Baranov PG, Ilyin VA, and Astakhov GV
- Abstract
Several systems in the solid state have been suggested as promising candidates for spin-based quantum information processing. In spite of significant progress during the last decade, there is a search for new systems with higher potential [D. DiVincenzo, Nat. Mater. 9, 468 (2010)]. We report that silicon vacancy defects in silicon carbide comprise the technological advantages of semiconductor quantum dots and the unique spin properties of the nitrogen-vacancy defects in diamond. Similar to atoms, the silicon vacancy qubits can be controlled under the double radio-optical resonance conditions, allowing for their selective addressing and manipulation. Furthermore, we reveal their long spin memory using pulsed magnetic resonance technique. All these results make silicon vacancy defects in silicon carbide very attractive for quantum applications.
- Published
- 2012
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39. Abnormal sebaceous gland differentiation in 10 kittens ('sebaceous gland dysplasia') associated with generalized hypotrichosis and scaling.
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Yager JA, Gross TL, Shearer D, Rothstein E, Power H, Sinke JD, Kraus H, Gram D, Cowper E, Foster A, and Welle M
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- Animals, Cat Diseases genetics, Cats, Female, Hypotrichosis pathology, Male, Sebaceous Gland Diseases pathology, Sebaceous Glands pathology, Cat Diseases pathology, Hypotrichosis veterinary, Sebaceous Gland Diseases veterinary
- Abstract
A rare congenital dermatosis, characterized by progressive hypotrichosis with variable scaling and crusting, occurred in 10 short-haired kittens in North America and Europe. Lesions appeared at between 4 and 12 weeks of age, commencing on the head and becoming generalized. The tail was spared in two kittens. Generalized scaling was mild to moderate, often with prominent follicular casts. Periocular, perioral, pinnal and ear canal crusting was occasionally severe. The skin was thick and wrinkled in two kittens. Histologically, the main lesion was abnormal sebaceous gland morphology. Instead of regular differentiation from basal cells to mature sebocytes, the glands were composed of a haphazard collection of undifferentiated basaloid cells, some partly vacuolated and a few containing eosinophilic globules. Mitotic figures and apoptotic cells were present in an irregularly thickened follicular isthmus. Lymphocytic mural folliculitis and mild sebaceous adenitis were rare. Orthokeratotic hyperkeratosis and follicular casts were present. Hair follicles were of normal density and were mostly in anagen, but some contained malacic hair shafts. Perforating folliculitis, leading to dermal trichogranuloma formation, occurred occasionally. Further biopsy samples taken at 2 years and at 3 and 4 years, respectively, from two kittens revealed similar but often more severe sebaceous gland lesions. Hair follicles were smaller, with many in telogen. The young age of onset suggests a genetic defect interfering with sebaceous and, possibly, follicular development. These lesions are discussed with reference to studies of mouse mutants in which genetic defects in sebaceous differentiation cause a similar phenotype of hyperkeratosis and progressive alopecia., (© 2012 The Authors. Veterinary Dermatology. © 2012 ESVD and ACVD.)
- Published
- 2012
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40. Successful treatment of osteitis fibrosa cystica from primary hyperparathyroidism.
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Maina AM and Kraus H
- Abstract
Osteitis Fibrosa Cystica (OFC) is defined as the classic skeletal manifestation of advanced primary hyperparathyroidism. With the increased detection by means of routine calcium screening, the clinical profile of primary hyperparathyroidism in Western countries has shifted from symptomatic disease to one with subtle or no specific symptoms ("asymptomatic" primary hyperparathyroidism). The authors describe a classical feature of advanced primary hyperparathyroidism due to a parathyroid adenoma and its successful treatment.
- Published
- 2012
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41. Reversible and irreversible interactions of poly(3-hexylthiophene) with oxygen studied by spin-sensitive methods.
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Sperlich A, Kraus H, Deibel C, Blok H, Schmidt J, and Dyakonov V
- Abstract
Understanding of degradation mechanisms in polymer:fullerene bulk-heterojunctions on the microscopic level aimed at improving their intrinsic stability is crucial for the breakthrough of organic photovoltaics. These materials are vulnerable to exposure to light and/or oxygen, hence they involve electronic excitations. To unambiguously probe the excited states of various multiplicities and their reactions with oxygen, we applied combined magneto-optical methods based on multifrequency (9 and 275 GHz) electron paramagnetic resonance (EPR), photoluminescence (PL), and PL-detected magnetic resonance (PLDMR) to the conjugated polymer poly(3-hexylthiophene) (P3HT) and polymer:fullerene bulk heterojunctions (P3HT:PCBM; PCBM = [6,6]-phenyl-C(61)-butyric acid methyl ester). We identified two distinct photochemical reaction routes, one being fully reversible and related to the formation of polymer:oxygen charge transfer complexes, the other one, irreversible, being related to the formation of singlet oxygen under participation of bound triplet excitons on the polymer chain. With respect to the blends, we discuss the protective effect of the methanofullerenes on the conjugated polymer bypassing the triplet exciton generation., (© 2011 American Chemical Society)
- Published
- 2011
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42. Observation of bi-polarons in blends of conjugated copolymers and fullerene derivatives.
- Author
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Savenije TJ, Sperlich A, Kraus H, Poluektov O, Heeney M, and Dyakonov V
- Subjects
- Electron Spin Resonance Spectroscopy, Fullerenes chemistry, Polymers chemistry
- Abstract
From a fundamental and application point of view it is of importance to understand how charge carrier generation and transport in a conjugated polymer (CP):fullerene blend are affected by the blend morphology. In this work light-induced electron spin resonance (LESR) spectra and transient ESR response signals are recorded on non-annealed and annealed blend layers consisting of alkyl substituted thieno[3,2-b]thiophene copolymers (pATBT) and the soluble fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) at temperatures ranging from 10 to 180 K. Annealing of the blend sample leads to a reduction of the steady state concentration of light-induced PCBM anions within the blend at low temperatures (T = 10 K) and continuous illumination. This is explained on the basis of the reducing interfacial area of the blend composite on annealing, and the high activation energy for electron diffusion in PCBM blends leading to trapped electrons near the interface with the CP. As a consequence, these trapped electrons block consecutive electron transfer from an exciton on a CP to the PCBM domain, resulting in a relatively low concentration charge carriers in the annealed blend. Analysis of the transient ESR data allows us to conclude that in annealed samples diamagnetic bi-polaronic states on the CPs are generated at low temperature. The formation of these states is related to the generation and interaction of multiple positive polarons in the large crystalline polymer domains present in the annealed sample.
- Published
- 2011
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43. Triplet exciton generation in bulk-heterojunction solar cells based on endohedral fullerenes.
- Author
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Liedtke M, Sperlich A, Kraus H, Baumann A, Deibel C, Wirix MJ, Loos J, Cardona CM, and Dyakonov V
- Abstract
Organic bulk-heterojunctions (BHJ) and solar cells containing the trimetallic nitride endohedral fullerene 1-[3-(2-ethyl)hexoxy carbonyl]propyl-1-phenyl-Lu(3)N@C(80) (Lu(3)N@C(80)-PCBEH) show an open circuit voltage (V(OC)) 0.3 V higher than similar devices with [6,6]-phenyl-C[61]-butyric acid methyl ester (PC(61)BM). To fully exploit the potential of this acceptor molecule with respect to the power conversion efficiency (PCE) of solar cells, the short circuit current (J(SC)) should be improved to become competitive with the state of the art solar cells. Here, we address factors influencing the J(SC) in blends containing the high voltage absorber Lu(3)N@C(80)-PCBEH in view of both photogeneration but also transport and extraction of charge carriers. We apply optical, charge carrier extraction, morphology, and spin-sensitive techniques. In blends containing Lu(3)N@C(80)-PCBEH, we found 2 times weaker photoluminescence quenching, remainders of interchain excitons, and, most remarkably, triplet excitons formed on the polymer chain, which were absent in the reference P3HT:PC(61)BM blends. We show that electron back transfer to the triplet state along with the lower exciton dissociation yield due to intramolecular charge transfer in Lu(3)N@C(80)-PCBEH are responsible for the reduced photocurrent., (© 2011 American Chemical Society)
- Published
- 2011
- Full Text
- View/download PDF
44. Rates of screening colonoscopy are not increased when women are offered a female endoscopist in a health promotion outreach program.
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Denberg TD, Kraus H, Soenksen A, Mizrahi T, Shields L, and Lin CT
- Subjects
- Aged, Cohort Studies, Colorado, Female, Health Care Surveys, Humans, Middle Aged, Colonoscopy statistics & numerical data, Health Promotion organization & administration, Mass Screening statistics & numerical data, Patient Preference, Sex Factors
- Abstract
Background: In surveys, almost 50% of women prefer a female endoscopist (FE) to perform their screening colonoscopies (SCOs)., Objective: To assess whether offering women an FE is associated with higher rates of SCOs., Design: Prospective cohort study., Setting: University of Colorado Hospital primary care clinics., Patients: Women of ages 50 to 69 years eligible for an SCO., Interventions: SCO offers through mail and telephone outreach, with and without an explicit FE option., Main Outcome Measurements: Outreach intervention differences in SCO completion rates and percentages of women requesting FE., Results: Of 396 women, 72 (18.2%) underwent SCO without difference by type of invitation. Women who received an FE invitation were more likely to request an FE than patients who received no invitation (44.2% and 4.8%, respectively, P < .001), but women who requested an FE were not more likely to undergo an SCO than those who did not., Limitations: SCO was offered through an outreach program rather than through in-clinic referrals. The study used a nonrandomized trial comparison group., Conclusions: Women offered an FE were not more likely to undergo an SCO than those who were not. This study is unique in describing outcomes associated with actual offers of an FE at the time of scheduling. More direct evidence is needed to support the notion that the absence of FEs is an important barrier to colorectal cancer screening among women., (Copyright © 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
45. Synchronous autotransfusion during cesarean hysterectomy.
- Author
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Hatfield T, Kraus H, McConnell D, and Nageotte M
- Subjects
- Adult, Blood Loss, Surgical, Blood Transfusion, Autologous, Cardiopulmonary Bypass, Female, Humans, Infant, Newborn, Male, Pregnancy, Pregnancy Outcome, Cesarean Section, Hysterectomy methods, Placenta Accreta surgery
- Abstract
Placenta accreta is associated with major morbidities including massive hemorrhage. We report a cesarean hysterectomy for placenta accreta with synchronous autotransfusion using a standard cardiopulmonary bypass machine. This technique requires complete intraoperative heparinization yet has the advantage of autotransfusion of autologous clotting factors and platelets in addition to red blood cells., (2010 Mosby, Inc.)
- Published
- 2010
- Full Text
- View/download PDF
46. Thermal rearrangement of thiocarbonyl-stabilised triphenylphosphonium ylides leading to (Z)-1-diphenylphosphino-2-phenylsulfenylalkenes.
- Author
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Aitken RA, Dawson G, Keddie NS, Kraus H, Slawin AM, Wheatley J, and Woollins JD
- Subjects
- Crystallography, X-Ray, Models, Molecular, Molecular Structure, Temperature, Alkynes chemical synthesis, Organophosphorus Compounds chemical synthesis, Sulfhydryl Compounds chemistry, Sulfur Compounds chemical synthesis
- Abstract
While thermolysis of thiocarbonyl-stabilised phosphonium ylides generally results in extrusion of Ph(3)PS to give alkynes, those with a P=CH function instead undergo a novel P to S transfer of a phenyl group to give (Z)-configured 1-phosphino-2-sulfenylalkenes of interest as bidentate ligands.
- Published
- 2009
- Full Text
- View/download PDF
47. Crystal structure of ZnWO(4) scintillator material in the range of 3-1423 K.
- Author
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Trots DM, Senyshyn A, Vasylechko L, Niewa R, Vad T, Mikhailik VB, and Kraus H
- Abstract
The behaviour of the crystal structure of ZnWO(4) was investigated by means of synchrotron and neutron powder diffraction in the range of 3-300 K. Thermal analysis showed the sample's melting around 1486 K upon heating and subsequent solidification at 1442 K upon cooling. Therefore, the structure was also investigated at 1423 K by means of neutron diffraction. It is found that the compound adopts the wolframite structure type over the whole temperature range investigated. The lattice parameters and volume of ZnWO(4) at low temperatures were parametrized on the basis of the first order Grüneisen approximation and a Debye model for an internal energy. The expansivities along the a- and b-axes adopt similar values and saturate close to 8 × 10(-6) K(-1), whereas the expansion along the c-axis is much smaller and shows no saturation up to 300 K. The minimum expansivity corresponds to the direction close to the c-axis where edge-sharing linkages of octahedra occur.
- Published
- 2009
- Full Text
- View/download PDF
48. Production of low-background CuSn6-bronze for the CRESST dark-matter-search experiment.
- Author
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Majorovits B, Kader H, Kraus H, Lossin A, Pantic E, Petricca F, Proebst F, and Seidel W
- Subjects
- Alloys chemistry, Equipment Design standards, Physics methods, Radioactivity, Research Design, Alloys standards, Astronomy methods, Cosmic Radiation
- Abstract
One of the most intriguing open questions in modern particle physics is the nature of the dark matter in our universe. As hypothetical weakly interacting massive particles (WIMPs) do interact with ordinary matter extremely rarely, their observation requires a very low-background detector environment regarding radioactivity as well as an advanced detector technique that allows for active discrimination of the still present radioactive contaminations. The CRESST experiment uses detectors operating at milli-Kelvin temperature. Energy deposition in the detectors is recorded via the simultaneous measurement of a phonon-mediated signal and scintillation emitted by the CaWO(4) crystal targets. The entire setup is made of carefully selected materials. In this note we report on the development of ultra-pure bronze (CuSn(6)) wire in small quantities for springs and clamps that are currently being used in the CRESST II setup.
- Published
- 2009
- Full Text
- View/download PDF
49. EuPA achieves visibility - an activity report on the first three years.
- Author
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Dunn MJ, Gil C, Kleinhammer C, Lottspeich F, Pennington S, Sanchez JC, Albar JP, Bini L, Corrales F, Corthals GL, Fountoulakis MM, Hoogland C, James P, Jensen ON, Jiménez C, Jorrín-Novo J, Kraus HJ, Meyer H, Noukakis D, Palagi PM, Penque D, Quinn A, and Rabilloud T
- Subjects
- Europe, History, 21st Century, Societies, Scientific history, Societies, Scientific trends, Proteomics education, Proteomics organization & administration, Societies, Scientific organization & administration
- Abstract
Plans for the European Proteomics Association (EuPA) were conceived and established during 2004 and 2005, and culminated in the formal inception of the organisation during the 4th HUPO World Congress held in Munich in 2005. The mission from the outset has been three-tiered and is to: i) strengthen the national Proteomics organizations in their efforts; ii) to co-ordinate and provide educational programs, and iii) to advance the networking of scientists through meetings, workshops and student exchange. Linked to the mission were objectives to emphasise the benefits and contributions of Proteomics to biological and industrial researchers, the general public and science policy makers in Europe. In addition, the EuPA set out to promote scientific exchange for all applications and technology development related to Proteomics, and coordinate joint activities of national Proteomics societies at the European level. To achieve these tasks an organisational structure was conceived whereby four Activity Committees (Conferences/Communications, Education, EuPA-HUPO-Interactions and Funding) were implemented and a General Council consisting of all member countries. The remarkable rise and progress the EuPA has achieved in this small time frame is reported here.
- Published
- 2008
- Full Text
- View/download PDF
50. Azeotropic reflux chromatography: an efficient solution to a difficult separation in the scale-up synthesis of spongistatin 1.
- Author
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O'Brien M, Diéguez-Vázquez A, Hsu DS, Kraus H, Sumino Y, and Ley SV
- Abstract
Azeotropic reflux chromatography (in which the eluent is continuously recycled by means of refluxing) was used to separate a mixture of spiroketal intermediates in the scale-up synthesis of spongistatin 1, leading to an improved separation and an approximately 35-fold reduction in the amount of solvent used.
- Published
- 2008
- Full Text
- View/download PDF
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