129 research outputs found

    lntracluster rearrangement of protonated nitric acid: Infrared spectroscopic studies of H^+(HNO_3)(H_2O)_n

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    Infrared spectra of clusters of protonated nitric acid and water exhibit a marked change with cluster size, indicating that an intracluster reaction occurs with sufficient solvation. In small clusters, H_2O binds to a nitronium ion core, but at a critical cluster size the NO^+_2 reacts. A lower bound of 174 kcal/mol is found for the proton affinity of HNO_3

    Vibrational spectroscopy of NO^+(H_2O)_n: Evidence for the intracluster reaction NO^+(H_2O)_n→H_3O^+(H_2O)_(n-2)(HONO) at n≄4

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    Infrared spectra of mass‐selected clusters NO^+(H_2O)_n for n=1 to 5 were recorded from 2700 to 3800 cm^(−1) by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second‐order Mþller–Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H_2O ligands bound to a nitrosonium ion NO^+ core. They possessed perturbed H_2O stretch bands and dissociated by loss of H_2O. The H_2O antisymmetric stretch was absent in n=1 and gradually increased in intensity with n. In the n=4 clusters, we found evidence for the beginning of a second solvation shell as well as the onset of an intracluster reaction that formed HONO. These clusters exhibited additional weak, broad bands between 3200 and 3400 cm^(−1) and two new minor photodissociation channels, loss of HONO and loss of two H_2O molecules. The reaction appeared to go to completion within the n=5 clusters. The primary dissociation channel was loss of HONO, and seven vibrational bands were observed. From an analysis of the spectrum, we concluded that the n=5 cluster rearranged to form H_3O^+(H_2O)_3(HONO), i.e., an adduct of the reaction products

    Infrared spectrum of the silicon hydride cation SiH_7^+

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    Silanium ions are an important class of hypervalent molecules, and the determination of their structure will yield insights into the nature of nonclassical bonding and provide a contrast to the bonding in carbonium ions. We report the infrared spectrum of the mass-selected silicon hydride cluster ion ^(28)SiH_7^+ detected by vibrational predissociation spectroscopy. Silanium ions were formed in a pulsed high pressure glow discharge and cooled by the subsequent supersonic expansion. Photodissociation spectra were obtained using a tandem time-of-flight mass spectrometer: (formula available in paper) ions were mass-selected and excited by a tunable infrared laser. The resulting photofragments were detected using a reflectron as a mass analyzer. We observed a vibrational band at 3865 cm^(-1), which was the only one observed from 3500 cm^(-1) to 4200 cm^(-1). This result suggests that the molecule might form a symmetric complex with the structure H_2⋅SiH_3^+⋅H_2, in contrast to the CH_7^+ which has the structure CH_5^+⋅H_2

    Infrared spectrum of the silicon hydride cation SiH_7^+

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    Silanium ions are an important class of hypervalent molecules, and the determination of their structure will yield insights into the nature of nonclassical bonding and provide a contrast to the bonding in carbonium ions. We report the infrared spectrum of the mass-selected silicon hydride cluster ion ^(28)SiH_7^+ detected by vibrational predissociation spectroscopy. Silanium ions were formed in a pulsed high pressure glow discharge and cooled by the subsequent supersonic expansion. Photodissociation spectra were obtained using a tandem time-of-flight mass spectrometer: (formula available in paper) ions were mass-selected and excited by a tunable infrared laser. The resulting photofragments were detected using a reflectron as a mass analyzer. We observed a vibrational band at 3865 cm^(-1), which was the only one observed from 3500 cm^(-1) to 4200 cm^(-1). This result suggests that the molecule might form a symmetric complex with the structure H_2⋅SiH_3^+⋅H_2, in contrast to the CH_7^+ which has the structure CH_5^+⋅H_2

    Risk factors for bladder neck contracture after transurethral resection of the prostate

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    Introduction Transurethral resection of the prostate (TURP) is the most frequently used treatment of benign prostate hyperplasia with a prostate volume of <80 mL. A long-term complication is bladder neck contracture (BNC). The aim of the present study was to identify the risk factors for BNC formation after TURP. Methods We conducted a retrospective analysis of all TURP primary procedures which were performed at one academic institution between 2013 and 2018. All patients were analyzed and compared with regard to postoperative formation of a BNC requiring further therapy. Uni- and multivariable logistic regression analyses (MVAs) were performed to identify possible risk factors for BNC development. Results We included 1368 patients in this analysis. Out of these, 88 patients (6.4%) developed BNC requiring further surgical therapy. The following factors showed a statistically significant association with BNC development: smaller preoperative prostate volume (p = 0.001), lower resected prostate weight (p = 0.004), lower preoperative levels of prostate-specific antigen (PSA, p < 0.001), shorter duration of the surgery (p = 0.027), secondary transurethral intervention (due to urinary retention or gross hematuria) during inpatient stay (p = 0.018), positive (≄100  CFU/mL) preoperative urine culture (p = 0.010), and urethral stricture (US) formation requiring direct visual internal urethrotomy (DVIU) postoperatively after TURP (p < 0.001), in particular membranous (p = 0.046) and bulbar (p < 0.001) strictures. Preoperative antibiotic treatment showed a protective effect (p = 0.042). Histopathological findings of prostate cancer (PCA) in the resected prostate tissue were more frequent among patients who did not develop BNC (p = 0.049). On MVA, smaller preoperative prostate volume (p = 0.046), positive preoperative urine culture (p = 0.021), and US requiring DVIU after TURP (p < 0.001) were identified as independent predictors for BNC development. Conclusion BNC is a relevant long-term complication after TURP. In particular, patients with a smaller prostate should be thoroughly informed about this complication

    Error-analysis and comparison to analytical models of numerical waveforms produced by the NRAR Collaboration

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    The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a joint effort between members of the numerical relativity, analytical relativity and gravitational-wave data analysis communities. The goal of the NRAR collaboration is to produce numerical-relativity simulations of compact binaries and use them to develop accurate analytical templates for the LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and extracting astrophysical information from them. We describe the results of the first stage of the NRAR project, which focused on producing an initial set of numerical waveforms from binary black holes with moderate mass ratios and spins, as well as one non-spinning binary configuration which has a mass ratio of 10. All of the numerical waveforms are analysed in a uniform and consistent manner, with numerical errors evaluated using an analysis code created by members of the NRAR collaboration. We compare previously-calibrated, non-precessing analytical waveforms, notably the effective-one-body (EOB) and phenomenological template families, to the newly-produced numerical waveforms. We find that when the binary's total mass is ~100-200 solar masses, current EOB and phenomenological models of spinning, non-precessing binary waveforms have overlaps above 99% (for advanced LIGO) with all of the non-precessing-binary numerical waveforms with mass ratios <= 4, when maximizing over binary parameters. This implies that the loss of event rate due to modelling error is below 3%. Moreover, the non-spinning EOB waveforms previously calibrated to five non-spinning waveforms with mass ratio smaller than 6 have overlaps above 99.7% with the numerical waveform with a mass ratio of 10, without even maximizing on the binary parameters.Comment: 51 pages, 10 figures; published versio

    Safety and clinical outcomes of rituximab therapy in patients with different autoimmune diseases: experience from a national registry (GRAID)

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    Introduction: Evidence from a number of open-label, uncontrolled studies has suggested that rituximab may benefit patients with autoimmune diseases who are refractory to standard-of-care. The objective of this study was to evaluate the safety and clinical outcomes of rituximab in several standard-of-care-refractory autoimmune diseases (within rheumatology, nephrology, dermatology and neurology) other than rheumatoid arthritis or non-Hodgkin's lymphoma in a real-life clinical setting. Methods: Patients who received rituximab having shown an inadequate response to standard-of-care had their safety and clinical outcomes data retrospectively analysed as part of the German Registry of Autoimmune Diseases. The main outcome measures were safety and clinical response, as judged at the discretion of the investigators. Results: A total of 370 patients (299 patient-years) with various autoimmune diseases (23.0% with systemic lupus erythematosus, 15.7% antineutrophil cytoplasmic antibody-associated granulomatous vasculitides, 15.1% multiple sclerosis and 10.0% pemphigus) from 42 centres received a mean dose of 2,440 mg of rituximab over a median (range) of 194 (180 to 1,407) days. The overall rate of serious infections was 5.3 per 100 patient-years during rituximab therapy. Opportunistic infections were infrequent across the whole study population, and mostly occurred in patients with systemic lupus erythematosus. There were 11 deaths (3.0% of patients) after rituximab treatment (mean 11.6 months after first infusion, range 0.8 to 31.3 months), with most of the deaths caused by infections. Overall (n = 293), 13.3% of patients showed no response, 45.1% showed a partial response and 41.6% showed a complete response. Responses were also reflected by reduced use of glucocorticoids and various immunosuppressives during rituximab therapy and follow-up compared with before rituximab. Rituximab generally had a positive effect on patient well-being (physician's visual analogue scale; mean improvement from baseline of 12.1 mm). Conclusions: Data from this registry indicate that rituximab is a commonly employed, well-tolerated therapy with potential beneficial effects in standard of care-refractory autoimmune diseases, and support the results from other open-label, uncontrolled studies

    Mittelalter im Labor

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    Mit diesem Band prĂ€sentiert das Schwerpunktprogramm 1173 der Deutschen Forschungsgemeinschaft „Integration und Desintegration der Kulturen im europĂ€ischen Mittelalter“ erste Ergebnisse seiner Arbeit. Von Anfang an war ihm die Aufgabe gestellt, das mittelalterliche Europa in transkultureller Perspektive und auf Wegen einer transdisziplinĂ€ren Wissenschaft zu erforschen und zu begreifen. Immer ging es darum, die disziplinĂ€r verfassten Einzelwissenschaften durch transdisziplinĂ€re Arbeit zu ergĂ€nzen. Das wissenschaftliche Anliegen des Programms ist es, das europĂ€ische Mittelalter von seinen geografischen RĂ€ndern und seinen kulturellen Differenzen her zu erforschen und zu beschreiben. Der holistischen Frage nach der Einheit Europas wird die innere Vielfalt als gegenstĂ€ndlicher Ausgangspunkt entgegengesetzt. Europa wird nicht als abgeschlossenes, kohĂ€rentes Gebilde verstanden, sondern als ein Kontinent, dessen permanente Austausch- und Wechselbeziehungen zwischen den verschiedenen Regionen und Kulturen ĂŒberhaupt erst zur Ausbildung seiner charakteristischen Merkmale gefĂŒhrt haben
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