Nitrogen bridgehead compounds part 14. Acylation of ethyl 6-methyl-4-oxo- -6,7,8,9-tetrahydro-pyrido(1,2-a)pyrimidine-3-carboxilate with isocyanates

The 9-carbamoyl derivatives /$\text{3}$–$\text{9}$/ can be prepared from title compound /$\text{1}$/ with isocyanates /$\text{2}$/. $\text{3}$–$\text{9}$ are mixtures of the cis /Z/ and trans /E/ imines and the enamine /e/. The equilibrium depends on the substituents R,X and on the solvent.     

Die Isolierung zweier Proteine, Glykoproteid I und ein Trypsininhibitor, aus den Samen der franz?sischen Bohne (Phaseolus vulgaris)

Ohne Zusammenfassung     

Hydrogen bonding in the urea dimers and adenine–thymine DNA base pair: anharmonic effects in the intermolecular H-bond and intramolecular H-stretching vibrations

The equilibrium structures, binding energies, vibrational harmonic frequencies, and the anharmonic corrections for two different (cyclic and asymmetric) urea dimers and for the adenine–thymine DNA base pair system have been studied using the second-order Møller–Plesset perturbation theory (MP2) method and different density functional theory (DFT) exchange–correlation (XC) functionals (BLYP, B3LYP, PBE, HCTH407, KMLYP, and BH and HLYP) with the D95V, D95V**, and D95V++** basis sets. The widely used a posteriori Boys–Bernardi or counterpoise correction scheme for basis set superposition error (BSSE) has been included in the calculations to take into account the BSSE effects during geometry optimization (on structure), on binding energies and on the different levels of approximation used for calculating the vibrational frequencies. The results obtained with the ab initio MP2 method are compared with those calculated with different DFT XC functionals; and finally the suitability of these DFT XC functionals to describe intermolecular hydrogen bonds as well as harmonic frequencies and the anharmonic corrections is assessed and discussed.     

Eine halbquantitative Methode zur Bestimmung von ?thylendiamin, Di?thylentriamin, Tri?thylentetramin und Wasser nebeneinander

Ohne Zusammenfassung     

Polycyclische aromatische Kohlenwasserstoffe

Ohne Zusammenfassung     

Magnetic resonance image reconstruction using trained geometric directions in 2D redundant wavelets domain and non-convex optimization

Reducing scanning time is significantly important for MRI. Compressed sensing has shown promising results by undersampling the k-space data to speed up imaging. Sparsity of an image plays an important role in compressed sensing MRI to reduce the image artifacts. Recently, the method of patch-based directional wavelets (PBDW) which trains geometric directions from undersampled data has been proposed. It has better performance in preserving image edges than conventional sparsifying transforms. However, obvious artifacts are presented in the smooth region when the data are highly undersampled. In addition, the original PBDW-based method does not hold obvious improvement for radial and fully 2D random sampling patterns. In this paper, the PBDW-based MRI reconstruction is improved from two aspects: 1) An efficient non-convex minimization algorithm is modified to enhance image quality; 2) PBDW are extended into shift-invariant discrete wavelet domain to enhance the ability of transform on sparsifying piecewise smooth image features. Numerical simulation results on vivo magnetic resonance images demonstrate that the proposed method outperforms the original PBDW in terms of removing artifacts and preserving edges.     

PRODUCTION OF PHOTOREACTIVEABLE LESION IN THE YEAST S. cerevisiae BY IRRADIATION WITH 193 nm EXCIMER LASER LIGHT

Abstract— Far-UV (193nm) excimer-laser irradiation of an excision-repair defective but photoreactivatiozn competent strain of Saccharomyces cerevisiae (XS774–6A) produces a significant amount of photoreactiveable DNA-lesions. The irradiation was applied by a laser planned for micro-surgery in ophthalmology using doses and dose rates even lower as needed during the surgical use. Irradiation experiments on solid agar plates show a sharp bordered area of growth-inhibition around the impact of the laser-beam up to a diameter of 2 cm even for a radiation-repair competent wildtype strain. In this area photoreactivation of cells is detectable, proving the induction of pyrimidine-dimers in cells surrounding the laser-beam impact zone.     

Photoionization,Structures, and Energetics of Na-Doped Formic Acid–Water Clusters

The influence of formic acid on water cluster aggregation has been investigated experimentally by mass spectrometry and tunable UV laser ionization applied to Na-doped clusters formed in the supersonic expansion of water vapors seeded with formic acid (FA) as well as theoretically using high level quantum chemistry methods. The mass spectra of Na−FA(H₂O)_n clusters show an enlarging of mass distribution toward heavier clusters with respect to the Na−(H₂O)_n clusters, suggesting similar mass distribution in neutral clusters and an influence of formic acid in water aggregation. Density functional theory and coupled-cluster type (DLPNO-CCSD(T)) calculations have been used to calculate structures and energetics of neutral and ionized Na−FA(H₂O)_n as well as neutral FA(H₂O)_n. Na-doped clusters are characterized by very stable geometries. The theoretical adiabatic ionization potential values match pretty well the measured appearance energies and the calculated first six electronic excited states show Rydberg-type characters, indicating possible autoionization contributions in the mass spectra. Finally, theoretical calculations on neutral FA(H₂O)_n clusters show the possibility of similarly stable structures in small clusters containing up to n=4–5 water molecules, where FA interacts significantly with waters. This suggests that FA can compete with water molecules in the starting stage of the aggregation process, by forming stable nucleation seed.     

长江中游地区酸雨及大气污染物对钢材破坏的研究

用铜/铁、铜/锌组成的大气腐蚀监测器(ACM),在各种大气环境条件下(相对湿度、温度、颗粒物、电解质薄层、大气污染物等)测量了大气腐蚀速度。用室外曝晒挂片试验研究了自然环境条件下酸雨和大气污染对钢材腐蚀的影响。腐蚀速度主要由大气中SO_2浓度、降水酸度、润湿因子(降雨量与降雨次数乘积)控制。本实验钢材的耐蚀性顺序为:WSPA>08CuP≈09CuTiRe>A_3F>~#15>>08F≈LS