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Jutta Langer Bernhard Schrader Volker Bastian Eberhard Jacob 《Fresenius' Journal of Analytical Chemistry》1995,352(5):489-495
Infrared spectra in the gaseous phase have been recorded for the first time for urea and the isotopomers urea-D4, urea-15N2 and urea-13C. On the base of these data a normal coordinate calculation has been performed, resulting in an optimized force field of urea, showing that, due to the very small intermolecular forces, the internal force constants increase by evaporation. This is especially true for the C=O-bond with a force constant increased by 10%.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthday, to whom since 1957 scientific contacts with the second author developed to a good friendship 相似文献
64.
Ivn Maisuls Cui Wang Matias E. Gutierrez Suburu Sebastian Wilde Constantin-Gabriel Daniliuc Dana Brünink Nikos L. Doltsinis Stefan Ostendorp Gerhard Wilde Jutta Ksters Ute Resch-Genger Cristian A. Strassert 《Chemical science》2021,12(9):3270
In this work, we describe the synthesis, structural and photophysical characterization of four novel Pd(ii) and Pt(ii) complexes bearing tetradentate luminophoric ligands with high photoluminescence quantum yields (ΦL) and long excited state lifetimes (τ) at room temperature, where the results were interpreted by means of DFT calculations. Incorporation of fluorine atoms into the tetradentate ligand favors aggregation and thereby, a shortened average distance between the metal centers, which provides accessibility to metal–metal-to-ligand charge-transfer (3MMLCT) excimers acting as red-shifted energy traps if compared with the monomeric entities. This supramolecular approach provides an elegant way to enable room-temperature phosphorescence from Pd(ii) complexes, which are otherwise quenched by a thermal population of dissociative states due to a lower ligand field splitting. Encapsulation of these complexes in 100 nm-sized aminated polystyrene nanoparticles enables concentration-controlled aggregation-enhanced dual emission. This phenomenon facilitates the tunability of the absorption and emission colors while providing a rigidified environment supporting an enhanced ΦL up to about 80% and extended τ exceeding 100 μs. Additionally, these nanoarrays constitute rare examples for self-referenced oxygen reporters, since the phosphorescence of the aggregates is insensitive to external influences, whereas the monomeric species drop in luminescence lifetime and intensity with increasing triplet molecular dioxygen concentrations (diffusion-controlled quenching).Pt(ii) and Pd(ii) complexes with unprecedented photophysical properties were developed. Encapsulation in nanoparticles boosted their performance while rendering them as self-referenced oxygen sensors. 相似文献
65.
Ali Elriati Karin Achilles Jutta Loose Hans-Hartwig Otto 《Monatshefte für Chemie / Chemical Monthly》2007,138(6):627-634
Summary. 4-Phenylazetidine-2-one was transformed into 4-phenylazetidine-1-alkanoic acids, which were reacted in the presence of diphenylphosphoroazidate
with amino acid esters and dipeptide esters yielding β-lactam peptides with different spacers between the lactam ring and
the peptide moiety. All structures were established by elementary analyses, HPLC, optical rotation, and spectroscopic data
and all new compounds were tested as inhibitors of PPE using standard procedures. Four compounds exhibited a weak activity compared with the standard inhibitor trifluoroacetyl-l-val-l-tyr-l-val. 相似文献
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Mads Peter Schreiber Veikko Komppa Margareta Wahlström Jutta Laine-Ylijoki 《Accreditation and quality assurance》2006,10(9):510-514
Executive summary In the CEN/STAR Trends Analysis workshop on Sampling, initiated by request of the Nordic Innovation Centre, specially invited experts provided presentations on demands about regulation concerning sampling quality, sampling standard developments, quality assurance systems and practical experience from different sampling situations and cases. The workshop arrived at recommendations on the importance of proper sampling for environmental and product control purposes, especially to support European regulations, trade agreements and monitoring of environment. Sampling is an integrated part of the whole measurement process and should therefore be especially considered from the viewpoint of the end-user of the results. There is a need for raising quality control issues in sampling and for the establishment of a more uniformly co-ordinated European quality system for sampling. With the standard methods available, there are in principle two different ways of achieving third party assessment of the sampling protocols and procedures: accreditation of sampling organisations based upon international, national, or in-house standards and methods, and certification of individual samplers’ competences for sampling. Several activities or efforts as well as research and standardisation needs for raising the quality issues in sampling were identified and presented in a paper by the workshop.All the presentations and Workshop Proceedings are electronically available on the Nordic Innovation Centre's web site at and more specifically at 相似文献
68.
Adrijana Radošević Luka Sopta Alfredo Višković 《Annali dell'Universita di Ferrara》2008,54(2):287-295
In order to analyze the thermal pollution of the Plomin bay induced by the used cooling water released from Plomin 1 and Plomin
2 thermal power plants, flow simulations and temperature field analysis were conducted. The measurements of the bay surface
temperature field were carried out as well as the corresponding 3D water flow simulations on the realistically modeled bay.
The accuracy of the simulation results was evaluated by the comparison of computed and measured surface temperatures. Furthermore,
numerical meshes of different density were used in order to determine model sensitivity where the results showed a significant
effect of the mesh density on the simulation results. Although the simulations obtained with a denser mesh yield more accurate
results and allow for the reconstruction of heated water surface flow with better reliability, the sparser mesh provided sufficiently
accurate results as well. The overall temperature field obtained with the numerical model agrees well with the measured temperature
values, which demonstrates the successful application of the 3D flow numerical model on the Plomin bay thermal pollution problem.
相似文献
69.
Simultaneous quantitative and qualitative analysis of aliskiren,enalapril and its active metabolite enalaprilat in undiluted human urine utilizing LC‐ESI‐MS/MS 下载免费PDF全文
Bjoern B. Burckhardt Jutta Tins Stephanie Laeer 《Biomedical chromatography : BMC》2014,28(12):1679-1691
The benefit–risk ratio of combined blocking by the direct renin inhibitor aliskiren and an angiotensin‐converting enzyme inhibitor (e.g. enalapril) on the renin–angiotensin–aldosterone system is discussed. No method was available for simultaneous determination of both drugs in urine. A novel sensitive method for simultaneous quantification in undiluted human urine was developed which enables systematic pharmacokinetic investigations, especially in poorly investigated populations like children. Matrix effects were clearly reduced by applying solid‐phase extraction followed by a chromatographic separation on XselectTM C18 CSH columns. Mobile phase consisted of methanol and water, both acidified with formic acid. Under gradient conditions and a flow rate of 0.4 mL/min the column effluent was monitored by tandem mass spectrometry with electrospray ionization. Calibration curves were constructed in the range of 9.4–9600 ng/mL regarding aliskiren, 11.6–12000 ng/mL for enalapril and 8.8–9000 ng/mL for enalaprilat. All curves were analyzed utilizing 1/x2‐weighted quadratic squared regression. Intra‐run and inter‐run precision were 3.2–5.8% and 6.1–10.3% for aliskiren, 2.4–6.1% and 3.9–7.9% for enalapril as well as 3.1–9.4% and 4.7–12.7% regarding enalaprilat. Selectivity, accuracy and stability results comply with current international bioanalysis guidelines. The fully validated method was successfully applied to a pharmacokinetic investigation in healthy volunteers. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Five-dimensional Einstein-Maxwell-Chern-Simons theory with a Chern-Simons coefficient lambda = 1 has supersymmetric black holes with a vanishing horizon angular velocity but finite angular momentum. Here supersymmetry is associated with a borderline between stability and instability, since for lambda > 1 a rotational instability arises, where counterrotating black holes appear, whose horizon rotates in the opposite sense to the angular momentum. For lambda > 2 black holes are no longer uniquely characterized by their global charges, and rotating black holes with vanishing angular momentum appear. 相似文献