2,248 research outputs found
Irreducible completely pointed modules of quantum groups of type
We give a classification of all irreducible completely pointed
modules over a characteristic zero field in which
is not a root of unity. This generalizes the classification result of
Benkart, Britten and Lemire in the non quantum case. We also show that any
infinite-dimensional irreducible completely pointed
can be obtained from some irreducible completely pointed module over the
quantized Weyl algebra .Comment: 25 page
Iridium-Catalyzed Silylation of Five-Membered Heteroarenes: High Sterically Derived Selectivity from a Pyridyl-Imidazoline Ligand.
The steric effects of substituents on five-membered rings are less pronounced than those on six-membered rings because of the difference in bond angles. Thus, the regioselectivities of reactions of five-membered heteroarenes that occur with selectivities dictated by steric effects, such as the borylation of C-H bonds, have been poor in many cases. We report that the silylation of five-membered-ring heteroarenes occurs with high sterically derived regioselectivity when catalyzed by the combination of [Ir(cod)(OMe)]2 (cod=1,5-cyclooctadiene) and a phenanthroline ligand or a new pyridyl-imidazoline ligand that further increases the regioselectivity. The silylation reactions with these catalysts produce high yields of heteroarylsilanes from functionalization at the most sterically accessible C-H bonds of these rings under conditions that the borylation of C-H bonds with previously reported catalysts formed mixtures of products or products that are unstable. The heteroarylsilane products undergo cross-coupling reactions and substitution reactions with ipso selectivity to generate heteroarenes that bear halogen, aryl, and perfluoroalkyl substituents
Extended trigonometric Cherednik algebras and nonstationary Schr\"odinger equations with delta-potentials
We realize an extended version of the trigonometric Cherednik algebra as
affine Dunkl operators involving Heaviside functions. We use the quadratic
Casimir element of the extended trigonometric Cherednik algebra to define an
explicit nonstationary Schr\"odinger equation with delta-potential. We use
coordinate Bethe ansatz methods to construct solutions of the nonstationary
Schr\"odinger equation in terms of generalized Bethe wave functions. It is
shown that the generalized Bethe wave functions satisfy affine difference
Knizhnik-Zamolodchikov equations in their spectral parameter. The relation to
the vector valued root system analogs of the quantum Bose gas on the circle
with pairwise delta-function interactions is indicated.Comment: 23 pages; Version 2: expanded introduction and misprints correcte
Low temperature atmospheric plasma sterilization of PET trackmembranes study
The research work illustrated the results of track membrane sterilization by low-temperature atmospheric plasma. The results showed the sterilization effect of plasma processing the samples at 30 and 60 seconds
Intracapillary leucocyte accumulation as a novel antihaemorrhagic mechanism in acute pancreatitis in mice
Background: Pancreatic infiltration by leucocytes represents a hallmark in acute pancreatitis. Although leucocytes play an active role in the pathophysiology of this disease, the relation between leucocyte activation, microvascular injury and haemorrhage has not been adequately addressed.Methods: We investigated intrapancreatic leucocyte migration, leucocyte extravasation and pancreatic microperfusion in different models of oedematous and necrotising acute pancreatitis in lys-EGFP-ki mice using fluorescent imaging and time-lapse intravital microscopy.Results: In contrast to the current paradigm of leucocyte recruitment, the initial event of leucocyte activation in acute pancreatitis was represented through a dose- and time-dependent occlusion of pancreatic capillaries by intraluminally migrating leucocytes. Intracapillary leucocyte accumulation (ILA) resulted in dense filling of almost all capillaries close to the area of inflammation and preceded transvenular leucocyte extravasation. ILA was also initiated by isolated exposure of the pancreas to interleukin 8 or fMLP, demonstrating the causal role of chemotactic stimuli in the induction of ILA. The onset of intracapillary leucocyte accumulation was strongly inhibited in LFA-1-/- and ICAM-1-/- mice, but not in Mac-1-/- mice. Moreover, prevention of intracapillary leucocyte accumulation led to the development of massive capillary haemorrhages and transformed mild pancreatitis into lethal haemorrhagic disease.Conclusions: ILA represents a novel protective and potentially lifesaving mechanism of haemostasis in acute pancreatitis. This process depends on expression of LFA-1 and ICAM-1 and precedes the classical steps of the leucocyte recruitment cascade
In Vitro Nephrotoxicity Studies of Established and Experimental Platinum-Based Compounds
Cisplatin is one of the most commonly used drugs for the treatment of various solid cancers. However, its efficacy is restricted by severe side effects, especially dose-limiting nephrotoxicity. New platinum-based compounds are designed to overcome this limitation. Previous investigations showed that the platinum(IV)–nitroxyl complex PN149 is highly cytotoxic in various tumor cell lines. In the present study, investigations with PN149 were extended to normal human kidney tubule epithelia. Coincident with higher intracellular platinum accumulation, the cytotoxicity of PN149 in the proximal tubule epithelial cell line ciPTEC was more pronounced compared to the established platinum chemotherapeutics cisplatin, carboplatin and oxaliplatin. Quantitative gene expression profiling revealed the induction of ROS-inducible and anti-oxidative genes, suggesting an oxidative stress response by PN149. However, in contrast to cisplatin, no pro-inflammatory response was observed. Genes coding for distinct DNA damage response factors and genes related to apoptosis were up-regulated, indicating the activation of the DNA damage response system and induction of the apoptotic cascade by PN149. Altogether, a comparable transcriptional response was observed for PN149 and the platinum chemotherapeutics. However, the lack of inflammatory activity, which is a possible cause contributing to toxicity in human renal proximal tubule epithelia, might indicate the reduced nephrotoxic potential of PN149
Organic modification of layered silicates for use as barrier pigments in coating systems
Functional coatings and the barrier pigments they contain are an indispensable part of corrosion or product protection. The frequently used layered silicates in their pure form often do not achieve a sufficient protection of the components or products. The barrier
effect of the silicates can be significantly improved through targeted organic modification. The general use of commercial (unmodified) silicates leads to an improvement in the barrier of about 20 %. In contrast, the use of modified silicates achieves an improvement of up to 80 % [1], due to the extent of the diffusion path [2]. Decisive for the diffusion path and therefore for the subsequent functionality of the barrier is the exfoliation and orientation of the silicates, which depends on the compatibility with the coating system. Due to the large number of coating systems and the associated binder classes, the silicates should be specifically adapted to the respective polymer by being modified with reactive groups, which represents the main focus of this work. As a first polymer system an epoxy matrix was chosen. Thus, commercial silicates were modified by an epoxy-oligomer matrix based on 1,4-butanediol diglycidyl ether. The produced silicates were examined with the aid of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The expansion of the layers and the attachment of the organic molecules were investigated using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)
A new method for direct rf power absorption studies in CMR materials and high T_c superconductors
The design, fabrication and performance of an apparatus for the measurement
of direct rf power absorption in colossal magnetoresistive (CMR) and
superconducting samples are described. The system consists of a self-resonant
LC tank circuit of an oscillator driven by a NOT logic gate. The samples under
investigation are placed in the core of the coil forming the inductance L and
the absorbed power is determined from the measured change in the current
supplied to the oscillator circuit. A customized low temperature insert is used
to integrate the experiment with a commercial Oxford Instruments cryostat and
temperature controller. The oscillator working in the rf range between 1 MHz to
25 MHz is built around an IC 74LS04. The temperature can be varied from 4.2 to
400 K and the magnetic field from 0 to 1.4 T. The apparatus is capable of
measuring direct power absorption in CMR and superconducting samples of volume
as small as 1/1000 cm^3 with a signal to noise ratio of 10:1. Further increase
in the sensitivity can be obtained by summing the results of repeated
measurements obtained at a given temperature. The system performance is
evaluated by measuring the absorbed power in La_0.7 Sr_0.3 MnO_3 (LSMO) CMR
manganite samples and superconducting Y Ba_2 Cu_3 O_7 (YBCO) samples at
different rf frequencies. All operations during the measurements are automated
using a computer with a menu-driven software system, user input being required
only for the initiation of the measurement sequence.Comment: 32 pages including 14 figure
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