Conformational analysis of N,N,N‐Trimethyl‐(3,3‐dimethylbutyl)ammonium iodide by NMR spectroscopy: a sterically hindered trans‐standard

A predominantly trans‐1,2‐disubstituted ethane system – N,N,N‐trimethyl‐(3,3‐dimethylbutyl)ammonium iodide – is of particular interest for conformational analysis, because it contains both an organic and a highly polar substituent, making it soluble and thus applicable to study in a large variety of solvents. The fraction of the trans conformer of this molecule in a wide range of protic and aprotic solvents was determined by the nuclear magnetic resonance proton couplings to be approximately 90%, in contrast to the previously assumed 100%. The consistently strong preference of the trans conformation should establish N,N,N‐trimethyl‐(3,3‐dimethylbutyl)ammonium iodide as a possibly useful ‘trans‐standard’ in conformational analysis, much more so than 1,2‐ditert‐butylethane, which has a poor solubility in many solvents. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly enantio- and diastereoselective tandem generation of cyclopropyl alcohols with up to four contiguous stereocenters

Three highly enantio- and diastereoselective one-pot procedures for the synthesis of cyclopropyl and iodocyclopropyl alcohols with up to four contiguous stereocenters are reported. Route 1 involves asymmetric addition of an alkylzinc reagent to an enal followed by diastereoselective cyclopropanation. Route 2 parallels route 1, except that iodoform is used to generate the zinc carbenoid, and the products are iodocyclopropyl alcohols. Route 3 entails asymmetric vinylation of an aldehyde with divinylzinc reagents and subsequent diastereoselective cyclopropanation.     

Using multiple attractor chaotic systems for communication

In recent work with symmetric chaotic systems, we synchronized two such systems with one-way driving. The drive system had two possible attractors, but the response system always synchronized with the drive system. In this work, we show how we may combine two attractor chaotic systems with a multiplexing technique first developed by Tsimring and Suschick to make a simple communications system. We note that our response system is never synchronized to our drive system (not even in a generalized sense), but we are still able to transmit information. We characterize the performance of the communications system when noise is added to the transmitted signal.     

Evaluation of <Superscript>166<Emphasis Type="Italic">m</Emphasis></Superscript>Ho: In search of photonuclear cross sections and trigger-level paths

Part of the Army Research Laboratory’s battery program is research in the viability of nuclear batteries. Particularly attractive is a nuclear battery that can be stored without loss of energy, and then turned on by some external signal. This paper describes the progress toward that goal.     

Rho0 production and possible modification in Au+Au and p+p collisions at square root [sNN] = 200 GeV

We report results on rho(770)(0)-->pi(+)pi(-) production at midrapidity in p+p and peripheral Au+Au collisions at sqrt[s(NN)]=200 GeV. This is the first direct measurement of rho(770)(0)-->pi(+)pi(-) in heavy-ion collisions. The measured rho(0) peak in the invariant mass distribution is shifted by approximately 40 MeV/c(2) in minimum bias p+p interactions and approximately 70 MeV/c(2) in peripheral Au+Au collisions. The rho(0) mass shift is dependent on transverse momentum and multiplicity. The modification of the rho(0) meson mass, width, and shape due to phase space and dynamical effects are discussed.     

Observation of the c3Πu-X1Σg+ intersystem transition in the absorption spectrum of P2

The observation of the c³Π_u-X¹Σ_g⁺ intersystem transition of P₂ is reported. The 6-0 band of the system was identified on high resolution absorption plates teken on the NRC 10-m vacuum spectrograph at Ottawa. A rotational analysis of the band is given together with that of the adjacent 5-0 band of the C¹Σ_u⁺-X¹Σ_g⁺ system, the upper level of which is involved in a mutual perturbation with the c³Π_u, v = 6 level. The interaction parameters for the perturbation are derived. It is proposed that the appearance of the 6-0 band of the c³Π_u-X¹Σ_g⁺ transition is due to intensity borrowing from the strong, allowed C¹Σ_u⁺-X¹Σ_g⁺ system. Accurate values for the energies of the c³Π_u, b³Π_g, and a³Σ_u⁺ states relative to the ground state are given. The analysis of two other bands, 2-0 and 7-0, of the C¹Σ_u⁺-X¹Σ_g⁺ system whose upper levels likewise interact strongly with the c³Π_u state are also given.