On some Hasse principles for homogeneous spaces of algebraic groups over global fields of positive characteristic

We extend to global function fields some Hasse principles for homogeneous spaces of connected linear algebraic groups proved earlier by several authors in the case of number fields. We also give some applications.     

Synthesis and chromatographic properties of a novel chiral stationary phase derived from heptakis(6-azido-6-deoxy-2,3-di-O-phenylcarbamoylated)-beta-cyclodextrin immobilized onto amino-functionalized silica gel via multiple urea linkages

A novel chiral stationary phase (PPHCDN7) was prepared by immobilization of heptakis(6-azido-6-deoxy-2,3-di-O-phenylcarbamoylated)-β-cyclodextrin (PPHCD) onto the surface of amino-functionalized silica gel via multiple urea linkages derived from an extended application of the Staudinger reaction. A wide range of structurally divergent racemic drugs and other compounds were successfully separated into their enantiomers under both normal and reversed-phase conditions. β-Adrenergic blockers and racemic tertiary, secondary and primary amines were readily separated using a mixture of methanol and aqueous triethylammonium acetate buffer. The optimal pH value for the separation falls in the range of 4.65 to 6.30. With atropine and isoproterenol, good enantioseparations with separation factors of >5 were easily attainable.     

Amplification of a cyclic mixed-metalloporphyrin tetramer from a dynamic combinatorial library through orthogonal metal coordination

A cyclic porphyrin tetramer, consisting of two bis-phosphine substituted zinc(II) porphyrin units and two Rh(III)TPP units, is selected and amplified virtually quantitatively from a dynamic combinatorial library using 4,4'-bipy as a scaffold and using orthogonal binding modes.     

Thymidine-modulated 5-fluorouracil metabolism in liver and RIF-1 tumors studied by 19F magnetic resonance spectroscopy.

19F Magnetic resonance spectroscopy was used to study the impact of the biochemical modulator thymidine (TdR) on the 5-fluorouracil (5FU) metabolism in the livers and radiation-induced fibrosarcoma (RIF-1) tumors of 5FU-treated C3H mice. The liver spectra measured after administration of 5FU (65 or 130 mg/kg IP) showed the 5 FU resonance and its catabolites alpha-fluoro-beta-ureidopropionic acid and alpha-fluoro-beta-alanine. At the latter dose, fluoronucleotide signal was also detected. The liver spectra of TdR-pretreated (500 mg/kg, IP) mice showed additional signals of fluoronucleotide and fluoronucleoside at both 5FU doses, while alpha-fluoro-beta-alanine was not detected. TdR pretreatment increased the half-life of 5FU in livers from 24 +/- 2 to 126 +/- 46 SEM min at the 5FU dose of 65 mg/kg and from 28 +/- 2 to 95 +/- 22 min at the 130 mg/kg dose (P less than .1 and P less than .01, respectively). TdR-pretreated mice had higher 5FU anabolite (fluoronucleotide + fluoronucleoside) levels in their RIF-1 tumors than nonpretreated mice that received the same 5FU doses (56 +/- 15 SEM vs. 0 arbitrary units at the 5FU dose of 65 mg/kg, and 88 +/- 21 vs. 10 +/- 3 arbitrary units at 130 mg/kg 5FU; P less than .0001). The percentage drop in tumor volume was enhanced in the mice that received TdR, from 27 +/- 4 SEM to 52 +/- 2 at the 5 FU dose of 65 mg/kg and from 24 +/- 3 to 65 +/- 4 at the 130-mg/kg dose (P less than .0001, both).     

Fast fission phenomena: A possible intermediate time scale between deep inelastic reactions and compound nucleus formation

The change of the FWHM of the mass distribution of the fission products as a function of angular momentum is interpreted as a signature for a mechanism which is intermediate between compound nucleus formation and deep inelastic reactions. An intermediate composite system is assumed to be formed during the reaction, which undergoes fission. This kind of mechanism can therefore be called fast fission phenomena. It is related to the existence of a long lifetime component in déep inelastic reactions. Within the framework of a simple statistical model a qualitative as well as a quantitative estimate is done for a particular system. The conditions under which such a mechanism can be observed are discussed.     

Investigation of the 40Ar + 197Au, 238U systems at 44 MeV/u

We have measured the angular correlation between two fragments emitted in the reactions Ar + Au and Ar + U at 44 MeV/u at GANIL. The aim was to investigate the amount of initial linear momentum transferred from the projectile to a fissioning nucleus. It turned out that this amount is much smaller than can be extrapolated from previous experiments. Furthermore, the probability of forming a fissioning nucleus is very small.     

ToF atom-probe fim study of LaB6 single crystals

The field evaporation mass spectra of LaB₆ are obtained with time-of-flight atom-probe field ion microscope in vacuum and in the presence of hydrogen, nitrogen and oxygen. The spectra are consistent with a preferential chemisorption of these gases on boron sites.     

Sorption and diffusion of toluene in isotropic and oriented linear polyethylene

Sorption and diffusion of toluene vapor in linear polyethylene with mass-fraction crystallinity between 0.48 and 0.82 and draw ratios λ up to 10 have been studied at 30°C. The sorbed concentration in the amorphous phase C_a is little affected by crystallinity, indicating that the free-volume fraction is roughly the same for all isotropic samples. However, the diffusion path becomes more tortuous with increasing crystalline content, thereby leading to a sixfold drop in the zero-concentration diffusion coefficient D₀. Drawing has more drastic effects, reducing C_a and D₀ by factors of 4 and 60, respectively, as λ increases to 10. These large changes result from the transformation of the initially spherulitic material into a fibrous structure, which is composed of aligned microfibrils with taut tie molecules lying on the outer boundaries. The effects of crystallinity and orientation on the concentration dependence of the diffusion coefficient are also discussed.     

Spinal effects of acupuncture stimulation assessed by proton density-weighted functional magnetic resonance imaging at 0.2 T

Signal changes can be detected by proton density-weighted functional imaging in both the brain and the spinal cord. These are attributed to changes in extravascular water proton (signal enhancement by extravascular protons) density during neuronal activation. In this study, we used this technique to detect correlations between acupoint stimulation and neural activity in the spinal cord. Stimulation of acupoints associated with treatment of sensorimotor deficits (LI4 and LI11) was performed on 11 volunteers. During stimulation, 8 of the 11 subjects had consistent functional activations in C6/C7. A bilateral activation pattern was common. Our findings show that acupoint stimulation modulates activity in the spinal cord.