Structure and stereochemistry of lactames and cyclic imides: Part VI. The structure of reaction products of 2-methylglutarimide with phenyllithium

On the basis of spectral and X-ray analyses it is established that the reaction of phenyllithium with substituted glutarimide derivatives results in the open-chain amidoketone, which can be cyclised upon the dehydration.     

Subthreshold production of neutral pions with Ar ions of 44 MeV/u

The production of neutral pions in nucleus nucleus collisions with 44 MeV/u Ar projectiles from the accelerator GANIL has been observed. The angular distributions indicate a collective production process, and the pion spectra reflect properties of the collision dynamics.     

S-adic L-Functions Attached to the Symmetric Square of a Newform

In order to apply the ideas of Iwasawa theory to the symmetricsquare of a newform, we need to be able to define non-archimedeananalogues of its complex L-series. The interpolated p-adic L-functionis closely connected via a "Main Conjecture" with certain Selmergroups over the cyclotomic Z_p-extension of Q. In the p-ordinarycase these functions are well understood. In this article we extend the interpolation to an arbitraryset S of good primes (not necessarily satisfying ordinarityconditions). The corresponding S-adic functions can be characterisedin terms of certain admissibility criteria. We also allow interpolationat particular primes dividing the level of the newform. One interesting application is to the symmetric square of amodular elliptic curve E defined over Q. Our constructions yieldp-adic L-functions at all primes of stable or semi-stable reduction.If p is ordinary or multiplicative the corresponding analyticfunction is bounded; if p is supersingular our function behaveslike log²(1 + T). 1991 Mathematics Subject Classification: 11F67,11F66, 11F33, 11F30     

Pion production in heavy ion reactions induced by16O and84Kr beams at 60 MeV per nucleon

Low energy ⁺ and ^– production cross sections have been measured in¹⁶O at 65 MeV/u and⁸⁴Kr at 60 MeV/u induced reactions on⁷Li,¹²C,²⁷Al,¹⁰⁸Ag and¹⁹⁷Au. The results are compared with a previous measurement obtained with¹⁶O at 93 MeV/u. Large deviations are observed between light and heavy ion data. At variance with¹⁶O, the ratios ^–/ ⁺ are independent of the target in the Krypton case. A change in the regime of the projectile-target mass scaling of cross-sections is observed with the heaviest projectile.Experiments performed at GANIL facility, F-14032 Caen, France     

New sorption materials based on polysiloxane xerogels with incorporated calix[4]arene: Synthesis and structure

Polysiloxane xerogels with incorporated (without covalent binding) 25,26,27,28-tetrahydroxycalix[4]arene molecules are prepared by hydrolytic polycondensation. The elemental analysis indicates the presence of incorporated macrocyclic molecules, as well as solvent molecules used in synthesis, in the composition of materials synthesized. These conclusions agree with the data of thermal analysis, IR spectroscopy, and ¹³C CP/MAS NMR. The adsorbents synthesized are characterized by the developed porous structure and are capable of extracting cesium ions from acidic aqueous media. It is found that the maximal amount of calix[4]arene molecules participating in cesium sorption is 40%.     

Applications of a simultaneous assay of ascorbic acid, dehydroascorbic acid and ascorbic sulphate in biological materials

A modified spectrophotometric assay for ascorbic acid and its derivatives based on their reaction with 2,4-dinitrophenylhydrazine (DNPH) is described. Using standard ascorbic acid or ascorbic sulphate solutions, together with animal tissue or compound diet extracts, the conditions for ascorbic acid degradation were determined. For the differential measurement of reduced ascorbic acid (AA), dehydroascorbic acid (dAA) and ascorbic sulphate (AS), five series of simultaneous determinations were performed. These included the use of (1) KBrO3 for the hydrolysis of AS, (2) 2,6-dichlorophenolindophenol as an oxidant, (3) DNPH to form a hydrazone derivative with dAA and (4 and 5) two blanks (where ascorbate was degraded) to correct for interfering substances. A variety of vertebrate and invertebrate tissues were examined for their ascorbate content, and the advantages of the modified procedure over currently available assays are discussed. The results suggest that the Artemia cyst is a unique material in which ascorbic sulphate is present in large amounts whereas fish tissues do not contain this form of vitamin C.     

Synthesis and structure-related adsorption characteristics of bifunctional polysiloxane xerogels with methyl and 3-mercaptopropyl groups

Polysiloxane xerogels containing 3-mercaptopropyl and methyl groups in the surface layer were synthesized by the sol-gel method with ethanol used as a solvent and fluoride ion used as a catalyst. It is established that an increase in the relative content of methyltriethoxysilane in the initial reaction mixture results in formation of xerogels with a developed porous structure. The tendency for an increase in other characteristics of porous structure, the sorption volume and pore size, is also observed. The analogous effect is found upon increasing relative content of tetraethoxysilane with a constant ratio between two trifunctional silanes. By means of atomic force microscopy, it is shown that the xerogels are composed of aggregated particles with mean sizes of 35–45 nm. These results correlate with the data of scanning electron microscopy. On the basis of the data of IR spectroscopy and ¹³C CP/MAS NMR spectroscopy, it is concluded that the surface layers contain not only 3-mercaptopropyl and methyl groups but also silanol groups, a part of the unhydrolyzed alkoxy groups, and water molecules involved in the formation of hydrogen bonds. The results obtained by ²⁹Si CP/MAS NMR spectroscopy testify that, in synthesized xerogels, the structural units of T¹ type [(≡SiO)Si(OR′)₂CH₃ and/or (≡SiO)Si(OR′)₂(CH₂)₃SH, R′ = H, OCH₃ or OC₂H₅] are absent and the structural units of T³ type [(≡SiO)₃SiCH₃ and (≡SiO)₃Si(CH₂)₃SH] dominate compared to the units of T² type [(≡SiO)₂Si(OR′)CH₃ and (≡SiO)₂Si(OR′)(CH₂)₃SH]. These results are an indirect indication of enhanced hydrolytic stability of surface layers in such xerogels.