Biomimetic synthesis of neodihydrothebaine and bractazonine from thebaine

Photochemical irradiation of the morphinan alkaloid thebaine 1 followed by reduction, affords the dibenz[d,f]azonine alkaloids neodihydrothebaine 2 and bractazonine 3, in a sequence paralleling the proposed biosynthesis of these alkaloids in Papaver bracteatum.     

Difference in thermal behaviour between 1- and 2-alkyl-5-(methoxycarbonyldiazomethyl)tetrazoles

In continuation of previous work, isomeric diazoester-substituted alkyltetrazoles 5 and 6 have been synthesized by the diazo-transfer method and studied in thermolysis reactions. Whereas the N-1 alkyl derivatives 5 give norcaradienes 7 in benzene solution and imidazotetrazoles 12 in acetonitrile, the more thermostable N-2 alkyl isomers 6 yield fluxional norcaradiene-cycloheptatriene systems, 10 – 11 , and ox-azoles 13.     

Measurability analysis of the electric-type components of the linearized gravitational radiation field

The equivalence principle as well as the spin-two character of the weak gravitational field lead to difficulties in the measurability analysis of this field which are not encountered in Bohr and Rosenfeld's corresponding inquiry into the electromagnetic field. To meet these difficulties, atomic elastic structures are proposed as gravitational field detectors whose parameters (masses, total volumes, lattice and elastic constants) are adjustable. The limitations imposed by the uncertainty principle and by the radiation reaction of the detectors on the determination of the amplitude, frequency, and direction of the field are then exhibited. Finally, the relevance of the present work to the investigation of DeWitt and to Einstein's full theory of gravitation is briefly considered.The research was partially supported by the AFOSR. This paper is a slightly modified version of the author's doctoral dissertation at Syracuse University.     

Persulfate and perphosphate oxidation of 2-propanol: A relative rate study

A competitive reaction study for two isoelectronic peroxides (peroxodisulfate S₂O and peroxodiphosphate P₂O) interacting with the free radical ·Clpar;CH₃)₂OH is described. The radical formation is initiated by photolysis, the amounts of peroxide remaining analyzed volumetrically. It is found that persulfate reacts with the organic radical over 100 times more rapidly than does perphosphate. Mechanistic consequences in relation to previous work are briefly discussed.     

Sources and mechanisms of wheel/rail noise: state-of-the-art and recent research

A review is presented of wheel/rail research studies, published since 1978. Additionally a study is presented which is focussed on the magnitudes and relative importance of vertical and horizontal forces in the wheel/rail contact zone. In the specific case and the frequency range 50–2000 Hz the vertical force appeared to be 3–10 times larger than the lateral (axial) force. Nevertheless radiation due to axial excitation of the wheel dominates the wayside sound pressure level in several one-third octave frequency bands. Another significant contribution to the wayside A-weighted sound pressure level is attributed to vertical excitation of the rail.     

Perpendicular giant magnetoresistance of magnetic multilayers

The theoretical and experimental studies of the giant magnetoresistance effect in metallic magnetic multilayers with measuring current perpendicular to the interface planes are reviewed. Theoretical formalisms of electronic transport in the inhomogeneous electron gas are critically compared with emphasis on the perpendicular magnetoresistance in multilayers. The effects of interface roughness, potential steps at the interfaces, and realistic band structures are addressed. The experimental determination of the perpendicular resistance of metallic multilayers requires either low-resistance measurement techniques or microfabricated samples with enhanced resistances. The experimental methods known at present are discussed and, where possible, compared with each other.     

Hybrid ceramic nanosieves: stabilizing nanopores with organic links

Unprecedented hydrothermal stability in functional membranes has been obtained with hybrid organic-inorganic nanoporous materials, enabling long-term application in energy-efficient molecular separation, including dehydration up to at least 150 degrees C.