42 research outputs found

    Reactions of noble-metal oxides in ionic liquids near room temperature

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    The reaction of Ag2_{2}O, Au2_{2}O3_{3}, and HgO with CuCl, CuI, AgCl, AgI, AuCl, and AuI in ionic liquids ([EMIm]Cl, [BMIm]Cl) near room temperature (20–80 °C) is evaluated and results in the new compounds (C8_{8}H14_{14}N2_{2})CuCl, (C8_{8}H14_{14}N2_{2})AgI, (C6_{6}H10_{10}N2_{2})AuCl, [(C8_{8}H14_{14}N2_{2})2_{2}Hg][CuCl3_{3}], [(C8_{8}H14_{14}N2_{2})2_{2}Hg][AgCl3_{3}], and [EMIm][Ag2_{2}I2_{2}Cl]. Thereof, (C8_{8}H14_{14}N2_{2})CuCl, (C8_{8}H14_{14}N2_{2})AgI, (C6_{6}H10_{10}N2_{2})AuCl, [(C8_{8}H14_{14}N2_{2})2_{2}Hg][CuCl3_{3}], and [(C8_{8}H14_{14}N2_{2})2_{2}Hg][AgCl3_{3}] are NHC complexes (NHC: N-heterocyclic carbene) with M–C bonds (M: Cu, Ag, Au, Hg). Whereas (C8_{8}H14_{14}N2_{2})CuCl and (C8_{8}H14_{14}N2_{2})AgI crystallize as single molecules, (C6_{6}H10_{10}N2_{2})AuCl is dimerized via aurophilic interactions. [(C8_{8}H14_{14}N2_{2})2_{2}Hg][CuCl3_{3}] and [(C8_{8}H14_{14}N2_{2})2_{2}Hg][AgCl3_{3}] exhibit Hg atoms with two Hg–C bonds. Moreover, (C8_{8}H14_{14}N2_{2})AgI shows intense green fluorescence at room temperature with a quantum yield of 44%, whereas all other compounds do not show any emission at room temperature. Finally, [EMIm][Ag2_{2}I2_{2}Cl] is not an NHC compound but contains ∞_{∞}1^{1}[AgI1/2_{1/2}I2/4_{2/4}Cl1/2_{1/2}]− chains with infinite d10^{10}–d10^{10} interaction of the silver atoms. The title compounds are characterized by single-crystal structure analysis, infrared spectroscopy, thermogravimetry, and fluorescence spectroscopy

    Excited-state quantum phase transitions in spinor Bose-Einstein condensates

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    Excited-state quantum phase transitions (ESQPTs) extend the notion of quantum phase transitions beyond the ground state. They are characterized by closing energy gaps amid the spectrum. Identifying order parameters for ESQPTs poses however a major challenge. We introduce spinor Bose-Einstein condensates as a versatile platform for studies of ESQPTs. Based on the mean-field dynamics, we define a topological order parameter that distinguishes between excited-state phases, and discuss how to interferometrically access the order parameter in current experiments. Our work opens the way for the experimental characterization of excited-state quantum phases in atomic many-body systems.Comment: 14 pages, 3 figure

    The proteome of human brain microdialysate

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    BACKGROUND: Cerebral microdialysis has been established as a monitoring tool in neurocritically ill patients suffering from severe stroke. The technique allows to sample small molecules in the brain tissue for subsequent biochemical analysis. In this study, we investigated the proteomic profile of human cerebral microdialysate and if the identified proteins might be useful predictors for disease characteristics in stroke for tissue at risk in the contralateral hemisphere. We analysed cerebral protein expression in microdialysate from three stroke patients sampled from the hemisphere contralateral to the lesion. Using a proteomic approach based on two-dimensional gel electrophoresis and subsequent mass spectrometry, we created a protein map for the global protein expression pattern of human microdialyste. RESULTS: We found an average of 158 ± 24 (N = 18) protein spots in the human cerebral microdialysate and could identify 95 spots, representing 27 individual proteins. Most of these have been detected in human cerebrospinal fluid before, but 10 additional proteins mainly of cerebral intracellular origin were identified exclusively in the microdialysate. CONCLUSIONS: The 10 proteins found exclusively in human cerebral microdialysate, but not in cerebrospinal fluid, indicate the possibility to monitor the progression of the disease towards deterioration. The correlation of protein composition in the human cerebral microdialysate with the patients' clinical condition and results of cerebral imaging may be a useful approach to future applications for neurological stroke diagnosis, prognosis, and treatment

    Optimal squeezing for high-precision atom interferometers

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    We show that squeezing is a crucial resource for interferometers based on the spatial separation of ultra-cold interacting matter. Atomic interactions lead to a general limitation for the precision of these atom interferometers, which can neither be surpassed by larger atom numbers nor by conventional phase or number squeezing. However, tailored squeezed states allow to overcome this sensitivity bound by anticipating the major detrimental effect that arises from the interactions. We envisage applications in future high-precision differential matter-wave interferometers, in particular gradiometers, e.g., for gravitational-wave detection.Comment: 10 pages, 4 figure

    Quantification of exhaled propofol is not feasible during single-lung ventilation using double-lumen tubes : A multicenter prospective observational trial

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    Background: Volatile propofol can be measured in exhaled air and correlates to plasma concentrations with a time delay. However, the effect of single-lung ventilation on exhaled propofol is unclear. Therefore, our goal was to evaluate exhaled propofol concentrations during single-lung compared to double-lung ventilation using double-lumen tubes. Methods: In a first step, we quantified adhesion of volatile propofol to the inner surface of double-lumen tubes during double- and single-lumen ventilation in vitro. In a second step, we enrolled 30 patients scheduled for lung surgery in two study centers. Anesthesia was provided with propofol and remifentanil. We utilized left-sided double-lumen tubes to separately ventilate each lung. Exhaled propofol concentrations were measured at 1-min intervals and plasma for propofol analyses was sampled every 20 min. To eliminate the influence of dosing on volatile propofol concentration, exhalation rate was normalized to plasma concentration. Results: In-vitro ventilation of double-lumen tubes resulted in increasing propofol concentrations at the distal end of the tube over time. In vitro clamping the bronchial lumen led to an even more pronounced increase (Δ AUC +62%) in propofol gas concentration over time. Normalized propofol exhalation during lung surgery was 31% higher during single-lung compared to double-lung ventilation. Conclusion: During single-lung ventilation, propofol concentration in exhaled air, in contrast to our expectations, increased by approximately one third. However, this observation might not be affected by change in perfusion-ventilation during singlelung ventilation but rather arises from reduced propofol absorption on the inner surface area of the double-lumen tube. Thus, it is only possible to utilize exhaled propofol concentration to a limited extent during single-lung ventilation. Registration of Clinical Trial: DRKS-ID DRKS00014788 (www.drks.de)

    Non-perturbative Test of the Witten-Veneziano Formula from Lattice QCD

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    We compute both sides of the Witten-Veneziano formula using lattice techniques. For the one side we perform dedicated quenched simulations and use the spectral projector method to determine the topological susceptibility in the pure Yang-Mills theory. The other side we determine in lattice QCD with Nf=2+1+1N_f=2+1+1 dynamical Wilson twisted mass fermions including for the first time also the flavour singlet decay constant. The Witten-Veneziano formula represents a leading order expression in the framework of chiral perturbation theory and we also employ leading order chiral perturbation theory to relate the flavor singlet decay constant to the relevant decay constant parameters in the quark flavor basis and flavor non-singlet decay constants. After taking the continuum and the SU(2)(2) chiral limits we compare both sides and find good agreement within uncertainties.Comment: 30 pages, 7 figures, version accepted for publicatio

    Low CO Luminosities in Dwarf Galaxies

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    [Abridged] We present maps of CO 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13 arcsec angular resolution, ~250 pc at our average distance of 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarfs outside the Local Group ranging from single lines-of-sight, stacked over IR-bright regions of embedded star formation, and stacked over the entire galaxy. We detect 5 dwarfs in CO with total luminosities of L_CO = 3-28 1e6 Kkmspc2. The other 11 dwarfs remain undetected in CO even in the stacked data and have L_CO < 0.4-8 1e6 Kkmspc2. We combine our sample of dwarfs with a large literature sample of spirals to study scaling relations of L_CO with M_B and metallicity. We find that dwarfs with metallicities of Z ~ 1/2-1/10 Z_sun have L_CO about 1e2-1e4x smaller than spirals and that their L_CO per unit L_B is 10-100x smaller. A comparison with tracers of star formation (FUV and 24 micron) shows that L_CO per unit SFR is 10-100x smaller in dwarfs. One possible interpretation is that dwarfs form stars much more efficiently, however we argue that the low L_CO/SFR ratio is due to significant changes of the CO-to-H2 conversion factor, alpha_CO, in low metallicity environments. Assuming a constant H2 depletion time of 1.8 Gyr (as found for nearby spirals) implies alpha_CO values for dwarfs with Z ~ 1/2-1/10 Z_sun that are more than 10x higher than those found in solar metallicity spirals. This significant increase of alpha_CO at low metallicity is consistent with previous studies, in particular those which model dust emission to constrain H2 masses. Even though it is difficult to parameterize the metallicity dependence of alpha_CO, our results suggest that CO is increasingly difficult to detect at lower metallicities.Comment: Accepted for publication in the Astronomical Journal, 19 pages, 7 figure

    {\eta} and {\eta}' mesons from Nf=2+1+1 twisted mass lattice QCD

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    We determine mass and mixing angles of eta and eta' states using Nf=2+1+1 Wilson twisted mass lattice QCD. We describe how those flavour singlet states need to be treated in this lattice formulation. Results are presented for three values of the lattice spacing, a=0.061 fm, a=0.078 fm and a=0.086 fm, with light quark masses corresponding to values of the charged pion mass in a range of 230 to 500 MeV and fixed bare strange and charm quark mass values. We obtain 557(15)(45) MeV for the eta mass (first error statistical, second systematic) and 44(5) degrees for the mixing angle in the quark flavour basis, corresponding to -10(5) degrees in the octet-singlet basis.Comment: 28 pages, 9 figures, version to appear in JHEP, extended discussion of autocorrelation times and comparison to results available in the literature, added a comment for FS-effects and clarified the description of our blocking procedur

    Cryogel-supported stem cell factory for customized sustained release of bispecific antibodies for cancer immunotherapy

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    Combining stem cells with biomaterial scaffolds provides a promising strategy for the development of drug delivery systems. Here we propose an innovative immunotherapeutic organoid by housing human mesenchymal stromal cells (MSCs), gene-modified for the secretion of an anti-CD33-anti-CD3 bispecific antibody (bsAb), in a small biocompatible star-shaped poly(ethylene glycol)-heparin cryogel scaffold as a transplantable and low invasive therapeutic machinery for the treatment of acute myeloid leukemia (AML). The macroporous biohybrid cryogel platform displays effectiveness in supporting proliferation and survival of bsAb-releasing-MSCs overtime in vitro and in vivo, avoiding cell loss and ensuring a constant release of sustained and detectable levels of bsAb capable of triggering T-cell-mediated anti-tumor responses and a rapid regression of CD33 + AML blasts. This therapeutic device results as a promising and safe alternative to the continuous administration of short-lived immunoagents and paves the way for effective bsAb-based therapeutic strategies for future tumor treatments
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