Azides of heavier main group elements: The reluctance of phosphine azides to undergo a curtius-type rearrangement

Under thermolytic or photolytic conditions, phosphine azide complexes Ph₂PN₃M(CO)₅ (M = W, Cr) gave rise to the corresponding isocyanato complexes and not to the expected iminophosphane complexes.     

Study of factorial moments in neutrino changed current interactions on neon and deuterium

Results are presented on the reduced scaled factorial moments of order 2,3,and 4 in ν_μ Ne and ν_μD₂ charged current interaction. Comparisons of the data with a Monte Carlo simulation are presented. The simulation is based on the Lund programs LEPTO 4.3 and JETSET 6.3 and including nuclear reinteractions and smearing due to measurement errors. Nuclear effects are shown to bias the estimate of the intermittency strenghts.     

Some observations on employing a panel's cill and reveal to enhance noise reduction

The cill and reveal of a panel or window are known to influence the Normalised Noise Reduction. Reported here are additional observations upon their effect which may be employed to increase the sound insulation of rooms within the built environment.     

Influence de la nature du ligand aromatique sur l′induction asymetrique observee lors de l′addition d′arylmethylsulfoxydes sur des carbonyles

The presence of an orthopyridyl substituent instead of a p-Tolyl on a chiral sulfoxide group increased drastically the asymmetric induction observed during the addition of arylmethylsulfoxide on carbonyl compounds.     

The unimolecular fragmentation of steroidal amides under electron impact. The role of intermediary ion-neutral complexes

The neutral fragment produced in the main decomposition process of 3-amido steroids after electron impact is shown, by thermochemical arguments, to have the amide structure rather than enolamide as would be expected from a simple McLafferty rearrangement. It is proposed that the enolamide to amide tautomerization takes place during the decomposition process involving ion-neutral complexes, and is responsible for the lack of regioselectivity in the origin of the hydrogen transferred. An energy barrier of unknown origin is shown to exist in the formation of the accompanying [amide + H]⁺ ion.     

A quantum-mechanical normal-mode approach to collinear collisions of identical diatomics. Perturbed stationary state formulation

A quantum mechanical perturbed stationary state study of the collinear collision of two identical diatomic molecules within the normal mode decomposition technique is presented. Various collision systems are investigated and are classified in three different groups according to their dynamical behaviour.     

Spin alignment and parity violation effects inρ 0 production in neutrino and antineutrino charged-current interactions

Most of the measured events on hydrogen, deuterium and neon targets from BEBC at CERN and the 15-foot Bubble Chamber at Fermilab are combined to measure spin-density matrix elements for ⁰ production in the current-fragmentation region in neutrino and antineutrino charged-current interactions. The spin-alignment parameter is found to be 0.08±0.11 for neutrino and 0.41±0.11 for antineutrino interactions. The parity-odd density matrix element Im(₁₀+_–10) is consistent with zero in both reactions. In the combined neutrino and antineutrino data an indication of parity violation is observed: Im _1–1=0.38±0.16 atx _B >0.2,Q ²>8 GeV² andz>0.6.     

Synthesis of Chiral Starburst Dendrimers from PHB-Derived Triols as Central Cores

Chiral triols 1 – 3 (‘tris(hydroxymethyl)methane’ derivatives), prepared from (R)-3-hydroxybutanoic acid and aldehydes, are used as center pieces of dendrimers. The triols may be employed as such or after attachment of spacers containing alkyl or aryl moieties (see 5 and 7 ). The branches combined with the original or elongated triols are those first reported by Fréchet ( 9 – 12 , benzyl ethers of 3,5-dihydroxybenzyl alcohol and bromide). In this way, 1st-, 2nd-, and 3rd-generation chiral dendrimers without ( 13 – 15 ), or with aliphatic ( 16 – 18 ) or aromatic ( 19 – 21 ) spacers are prepared. The molecular weights range from 447 to 2716 Dalton. Two of the chiral triols, i.e., 2 and 3 , are used as center pieces for chiral dendrimers containing 6 NH₂, or 6 and 12 NO₂ groups on the periphery ( 22 – 27 ), with 3,5-dinitrobenzoyl chloride as the branching unit. All compounds thus synthesized are of course monodisperse and are fully characterized. In some cases, the optical activity of the dendrimers indicates that conformationally chiral substructures might be present. The NH₂- and NO₂-substituted compounds avidly clathrate smaller molecules; they are sorbents exchanging host molecules through the gas phase.     

Production of certified reference materials for the detection of genetically modified organisms

Certified reference materials (CRMs) are an essenIial tool in the quality assurance of analytical measurements. They are produced, certified, and used in accordance with relevant ISO (International Organization for Standardization) and BCR (Community Bureau of Reference) guidelines. The Institute for Reference Materials and Measurements (IRMM; Geel, Belgium) has produced the first powdery genetically modified organism (GMO) CRMs in cooperation with the Institute for Health and Consumer Protection (Ispra, Italy). Until now, different weight percentages in the range of 0-5% for 4 GMOs in Europe were produced and certified: Bt (Bacillus thuringiensis)-11 and Bt-176 maize, Roundup Ready soybean, and MON810 maize. Bt-11 and Bt-176 maize and Roundup Ready soybean were produced by IRMM on behalf of Fluka Chemie AG (Buchs, Switzerland). Characterization of used base material is the first step in production and is especially important for GMO CRMs. The production of powdery GMO CRMs and methods used for production control are described. Thorough control of homogeneity and stability are essential for certification of reference materials and ensure validity of the certificate for each bottle of a batch throughout a defined shelf-life. Because production of reference materials and their maintenance are very labor- and cost-intensive tasks, the usefulness of new types of GMO CRMs must be estimated carefully.