Determination of docosahexaenoic acid and n-3 fatty acids in refined fish oils by 1H-NMR spectroscopy: IUPAC interlaboratory study

A high-resolution proton nuclear magnetic resonance (NMR) method for determining the concentration (mg/g) of docosahexaenoic acid (DHA), the molar proportion (mol%) of DHA, and the molar proportion of total n-3 fatty acids in fish oils was validated by an IUPAC interlaboratory study (the Commission VI-6 on Oils, Fats, and Derivatives WG 3/98). Thirteen laboratories from 5 countries tested 6 pairs of blind duplicate fish oils: a refined tuna oil, 2 extracted tuna oils, an extracted bonito oil, an extracted salmon oil, and an extracted sardine oil ranging from 9 to 30 mol% DHA and from 20 to 35 mol% n-3 fatty acids. Before 1 D-proton NMR measurements with 300-500 MHz instruments, oil samples were weighed and diluted with deuterochloroform solution containing ethylene glycol dimethyl ether as internal standard. To achieve precise performance, a detailed procedure for signal area measurement was described in the protocol, and all participants were instructed about the critical importance of following the protocol. Statistical performances with invalid and outlier data removed were as follows: repeatability relative standard deviations (RSDr) ranged from 0.91 to 2.62% and reproducibility relative standard deviation (RSDR) ranged from 1.73 to 4.27% for DHA concentration (mg/g); RSDr ranged from 0.39 to 2.06%, and RSDR ranged from 0.59 to 3.46% for mol% DHA; RSDr ranged from 0.23 to 0.90% and RSDR ranged from 0.85 to 2.01 % for mol% total n-3 fatty acids. The method is expected to be recommended by IUPAC.     

A Recollection of Some Results and a Few Remarks on Structural Optimisation

Basic points of some papers on Optimal Design, published by the authors many years ago, are here presented. This seemed the more suitable choice for recalling the bonds of friendship and academic life that related them for many decades with Giulio Maier. Sommario. Sono richiamati gli aspetti essenziali di alcuni lavori, in tema di ottimizzazione strutturale, pubblicati dagli autori diversi anni orsono. Questa scelta è sembrata la più opportuna per ricordare i legami di amicizia e di vita accademica che da molti decenni intercorrono con Giulio Maier.     

Solid mechanical problems in the “Risorgimento” generation

We want to give a synthetic idea of the history of some arguments of the solid mechanics drawn up in Italy during the last four decades of the 19th Century (Your virtue is to be corious; you want to penetrate into the causes, to go back to the seeds. … I know how from one of those trifles, that the uninitiated don’t get, you scientists can get out the spark, that gave light to the most remote truths./Voi … avete la virtù di essere curiosi; volete penetrare nelle cause, rimontare al seme. … So come da una di quelle inezie, le quali sfuggono all’attenzione dei profani, voi scienziati potete cavare la scintilla, che rischiara poi le verità più riposte.), Boito (Senso, 1883). The expression Risorgimento Generation is ascribable to Giovan Battista Guccia (1855–1914), with reference to the school of Francesco Brioschi (1824–1897), as inspiration of the foundation (1884) of the Mathematical Society of Palermo.     

Coherent peaks and minimal probing depth in photoemission spectroscopy of Mott-Hubbard systems

We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (V(2)O(3)) across its metal-insulator transition. We show that, in the metallic phase, a clear correlation exists between the shakedown satellites observed in the vanadium 2p and 3p core-level spectra and the coherent peak measured at the Fermi level. Comparing experimental results and dynamical mean-field theory calculations, we estimate the Hubbard energy U in V(2)O(3) (4.20+/-0.05 eV). From our bulk-sensitive photoemission spectra we infer the existence of a critical probing depth for investigating electronic properties in strongly correlated solids.     

Spectral Tau approximation of the two-dimensional stokes problem

Summary We analyse the Spectral Tau method for the approximation of the Stokes system on a square with Dirichlet boundary conditions. We provide an error estimate, in the norm of the Sobolev spaceH ^s, for the approximation of a divergence free vector field with polynomial divergence free vector fields. We apply this result to prove some convergence estimates for the solution of the discrete Stokes problem.This work has been partially supported by the U.S. Army through its European Research Office under contract No. DAJA-84-C 0035     

Equation of state data for iron at pressures beyond 10 Mbar

We present equation of state points for iron, in the pressure range 10-45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.     

Efficient use of quantum resources for the transmission of a reference frame

We propose a covariant protocol for transmitting reference frames encoded on N spins, achieving sensitivity N-2 without the need of a preestablished reference frame and without using entanglement between sender and receiver. The protocol exploits the use of equivalent representations that were overlooked in the previous literature.     

On the reliability theory of the structures

Summary The researches into the reliability theory of the structures, in hypothesis of elasto-plastic material, compels one to determine the probability function of structural resistance. As it is very difficult to find this function exactly, various authors approximate its values following different methods.The paper starts from the comparison among these ways and proposes as more efficient a simulation method based on parametric linear programming. To the latter it gives an appropriate physical interpretation that allows one to be able to control the computational process.

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Sommario Le difficoltà di determinare la distribuzione di probabilità della resistenza di strutture elasto-plastiche (costruite con materiale a resistenza aleatoria) hanno spinto molti autori a mettere a punto metodi approssimati. Partendo da un esame comparativo si propone, in questa sede, una tecnica di simulazione, che sembra dotata di particolare efficienza computazionale, basata sulla programmazione lineare parametrica. Di essa viene data anche una interpretazione fisica che consente di controllare il processo di calcolo.

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Research conducted under a grant of C.N.R. and accepted by the 15th Polish Solid Mechanics Conference. Zakopane, September 1973.     

State-resolved reactivity of CH4(2nu3) on Pt(111) and Ni(111): effects of barrier height and transition state location

Quantum state-resolved sticking coefficients on Pt(111) and Ni(111) surfaces have been measured for CH4 excited to the first overtone of the antisymmetric C-H stretch (2nu3) at well-defined kinetic energies in the range of 10-90 kJ/mol. The ground-state reactivity of CH4 is approximately 3 orders of magnitude lower on Ni(111) than on Pt(111) for kinetic energies in the range of 10-64 kJ/mol, reflecting a difference in barrier height of 28+/-6 kJ/mol. 2nu3 excitation of CH4 increases its reactivity by more than 4 orders of magnitude on Ni(111), whereas on Pt(111) the reactivity increase is lower by 2 orders of magnitude. We discuss the observed differences in the state-resolved reactivity for the ground state and 2nu3 excited state of methane in terms of a difference in barrier height and transition state location for the dissociation reaction on the two metal surfaces.