DETECTION OF DNA-PSORALEN PHOTOADDUCTS in situ

Abstract— An immunological method, with the use of specific immune serum, has been developed for detection of 8-methoxypsoralen (8-MOP) photoadducts to DNA, formed in situ in cell nuclei, after combined treatment with 8MOP and UV-A irradiation (Zarçbska et al. , 1978). Lymphocytes fixed on slides or in suspension, and cryostat sections of different mammalian tissues, served as antigenic substrate, after treatment with 8-MOP and UV-A in vitro. Specific fluorescence in these substrates was detected in the nuclei after treatment with 30 ˜ 140 kJ/m² UV-A in the presence of 0.1-0.3 μg/cm² 8-MOP. PHA-stimulated-lymphocytes appeared to be the most sensitive substrate.
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m² did not reveal a specific fluorescence of epidermal nuclei, unless a high local concentration of 8-MOP was attained.
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed.     

31P and 13C chemical shielding tensors in the phosphoenolpyruvate moiety from rotary resonance recoupling 13C and 31P MAS and single crystal 31P NMR

A ³¹P and ¹³C NMR study of powder and single crystal samples of two phosphoenolpyruvate (PEP) compounds, the tris-ammonium salt monohydrate (NH₄)₃(PEP)·H₂O (1), and the mono-ammonium-salt (NH₄)(H₂PEP) (2) is presented. The P chemical shielding tensors in 1 are measured by ³¹P single crystal NMR on four minuscule samples and assigned without ambiguity by exploiting the orientation-dependent ³¹P-³¹p dipolar splittings of the resonance lines. The orientation of the ³¹P chemical shielding tensor is discussed in terms of the C_2v — and C₃-type distortions of the phosphate PO₄-coordination sphere. From ¹³C MAS NMR experiments with ³¹P rotary resonance recoupling on polycrystalline powder samples the orientations of the ³¹P chemical shielding tensors in 1 and 2 are obtained, for 1 in very good agreement with the ³¹P single crystal NMR results. Only some of the orientational parameters of the three ¹³C chemical shielding tensors in the PEP moiety of 1 could be derived from ¹³C MAS NMR experiments with ³¹P rotary resonance recoupling.     

Nonlinear electric properties of alkali metal halides

The first and second hyperpolarizabilities as well as the dipole moments and dipole polarizabilities are studied for a series of the alkali metal halides (MeX, Me = Li, Na, K, X = F, Cl, Br). The static results have been calculated at various levels of including the electron correlation contribution. The frequency-dependent data for different nonlinear optical processes correspond to TDHF calculations and can be approximately scaled for the electron correlation contribution. The present study also gives a systematic comparison of the performance of the so-called Pol basis sets and the recently developed basis sets (HyPol) designed for calculations of electric hyperpolarizabilities. Several regularities in the calculated data are observed and discussed in terms of ionic models supplemented by the electron density confinement effect. For some of the studied systems the first and second hyperpolarizabilities are found to have interestingly high values, comparable to those for molecules used in nonlinear optical materials.     

Synthesis,Crystal Structure and Theoretical Calculations of N-Benzyl-1-(5-(3-chlorophenyl)-1,3,4-oxadiazol-2-yl)cyclopentanamine

N-benzyl-1-(5-(3-chlorophenyl)-1,3,4-oxadiazol-2-yl)cyclopentanamine was synthesized via one-pot reaction of appropriate benzylamine, cyclopentanone,(N-isocyanimino)triphenylphosphorane and m-chlorobenzoic acid. The quantum theoretical calculations for crystal structure were performed by density functional theory(DFT/B3LYP/6-311+G*). From the optimized structure, geometric parameters were obtained and experimental measurements were compared with the calculated data. Frontier molecular orbitals(FMOs), total density of states(DOS), molecular electrostatic potential(MEP), molecular properties, natural charges, NMR parameters and NBO analysis for the product were investigated by theoretical calculations.     

Spectroscopic studies of the lanthanide(III) ions with pyridine carboxylic acid N-oxide ligands and in mixed ligand complexes

A series of Ln(III) complexes with pyridine carboxylic acid-N-oxides (L) Ln-L, and mixed ligand complexes of Ln-L plus bipyridine (bipy) or 1,10-phenanthroline (O-phen) (X) Ln-L-X have been studied. These complexes were characterized in solution using Nd(III) absorption in the spectral range of the ⁴I_9/2 → ⁴G_5/2 transition corresponding to the hypersensitive band, and in the solid state with the use of IR and Eu(III) luminescence spectroscopy. In solutions a series of Nd(III) complexes and mixed ligand complexes has been examined and the formation of binary LnL and LnL₂ complexes and mixed ligand LnL₂X complexes evidenced. Solid complexes of Eu(III) with nicotinic acid N-oxide and ternary with nicotinic acid N-oxide plus phen were studied with the use of Eu(III) luminescence lifetime measurements and IR spectroscopy, proving the formation of binary [Eu(nicN-oxide)₃(H₂O)₂].2H₂O and ternary [Eu(nicN-oxide)₃phen].H₂O complexes.     

Ultra-clean Si(111) and Si(001) Surfaces Prepared by Advanced Wet Chemical Cleaning

Wet chemical cleaning of silicon is a critical step, e.g., pre-gate clean, in the semiconductor manufacturing^[1]. For example, pre-gate oxide cleaning demands ultra-clean silicon surface with least surface roughness. It is well known that metallic infinities and roughness cause the lower breakdown voltage in gate dielectric^[2]. It has stringent requirements for ultra-clean and atomically flat silicon surface as the thickness of gate oxide is decreasing. In the present work, we have extended our study on Si(100) surface13] and extensively investigated wet chemical cleaning of Si(111) and Si(100) surfaces in NH₄F-based solutions by using scanning tunneling microscopy (STM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and total reflection X-ray fluorescence spectrometry (TXRF). Surface roughness, organic contamination, metallic impurities and surface termination on the silicon surfaces after wet chemical cleaning with various NH₄F-based solutions have been determined and compared with those treated with RCA cleans, HF solutions and other industrially used solutions. Our results indicate that ultra-clean and smooth Si(111) and Si(001) surfaces are obtained by treatment with NH4F-based solutions.