Magnetic rotation observation of the C2b3Σg− ← a3Πu transition using a color center laser

The magnetic rotation observation of the C₂b³Σ_g^? ← a³Π_u Ballik-Ramsay system using a color center laser is reported. This is the first detection of this system in absorption. Three bands, 0 ← 1, 1 ← 2, and 2 ← 3, were identified in the spectral range 3650–4030 cm^?1. The last two bands were observed for the first time. In magnetic rotation many satellite lines (ΔN ≠ ΔJ) which would be very weak in normal absorption have been observed with intensity comparable to the main branch lines. This permits a slight improvement in the accuracy of some of the fine structure constants. A variety of lineshapes are observed for the various branches by magnetic rotation. Because the b³Σ_g^? fine structure is small, giving a partial overlap, the peak frequency of a magnetic rotation signal usually does not correspond to the center frequency of the normal absorption signal of that transition. A computer program has been written to predict magnetic rotation lineshapes and obtain the peak frequency displacements. Various observed and calculated lineshapes are displayed and compared.     

Improvement of the inverse-gated-decoupling sequence for a faster quantitative analysis of various samples by 13C NMR spectroscopy

The inverse-gated-decoupling sequence enables quantitative (1)H decoupled (13)C spectra to be obtained. We modified this sequence so as to obtain the same result in less time for molecules containing carbons with various relaxation properties. For that, we determined the optimal (13)C longitudinal-magnetization initial value for a faster relaxation while (1)H decoupler is stopped. This value can be calculated precisely via the nuclear Overhauser effects, the longitudinal relaxation times, together with the determination of the relaxation rate constants of carbons while (1)H are out of equilibrium. A supplementary delay of (1)H decoupling and/or a series of selective pulses applied at the beginning of the recovery delay allow an acceleration of (13)C longitudinal relaxation. We applied this method to the molecule of vanillin. The simultaneous quantification of all carbons was carried out with a recovery delay divided by two compared to the usual sequence.     

Random infinite-volume Gibbs states for the Curie-Weiss random field Ising model

An approach to the definition of infinite-volume Gibbs states for the (quenched) random-field Ising model is considered in the case of a Curie-Weiss ferromagnet. It turns out that these states are random quasi-free measures. They are random convex linear combinations of the free product-measures shifted by the corresponding effective mean fields. The conditional self-averaging property of the magnetization related to this randomness is also discussed.This paper is dedicated to Robert A. Minlos on the occasion of his 60th birthday.     

MRI contrast-dose relationship of manganese(III)tetra(4-sulfonatophenyl) porphyrin with human xenograft tumors in nude mice at 2.0 T

Previously we reported that Mn(III)tetra(4-sulfonatophenyl) porphyrin, MnTPPS₄, is a contrast agent which can effectively enhance tumor detection by MRI. By imaging 30 additional athymic nude mice bearing subcutaneous MCF-7 WT human breast carcinoma xenografts, we have extended dose-contrast relationships over a wide range of intraperitoneal (IP) doses ranging from 0.025 to 0.50 mmol/kg. The benefits of IP injection are higher possible doses on a volume basis and a reduction in toxicity versus IV administration. Full coronal cross-section images have been obtained on a 2-T spectrometer. Although individual tumor masses displayed different distribution patterns, reflective of their internal morphology, single doses of 0.10 mmol/kg or greater were necessary to produce a detectable effect. At a dose of 0.50 mmol/kg, marked enhancement was produced. Multiple small dosages administered over the course of several days before imaging did not produce increased enhancement. Preliminary results on the new porphyrin derivative, MnTPPS₃, indicate that the ratio of the toxic dose to the effective dose may be adjustable to render this class of agents clinically useful.     

Towards molecular-scale electronics and biomolecular self-assembly

This paper provides an overview of recent research developments in the field of nanoelectronics with organic materials such as carbon nanotubes and DNA-templated nanowires. Carbon nanotubes and gold electrodes are chemically functionalized in order to contact carbon nanotubes by self-assembly. The transport properties of these nanotubes are dominated by charging effects and display clear Coulomb blockade behaviour. A different approach towards nanoscale electronics is based on the molecular recognition properties of biomolecules such as DNA. As an example, DNA is stretched between electrodes using a molecular combing technique. A two-step metallization procedure leads to the formation of highly conductive gold nanowires.     

Toward an ideal integrating nephelometer

The Integrating Sphere Integrating Nephelometer is a novel and unique reciprocal nephelometer that uses an integrating sphere with attached truncation-reduction tubes to contain the sample volume and to integrate the scattered light. Its main advantage compared with current integrating nephelometers is a sevenfold reduction in truncation angle, which reduces errors in measured scattering from large particles. Additional features include improved sampling efficiency for large particles and a well-defined operating wavelength.     

Aspects of Generic Entanglement

We study entanglement and other correlation properties of random states in high-dimensional bipartite systems. These correlations are quantified by parameters that are subject to the ``concentration of measure' phenomenon, meaning that on a large-probability set these parameters are close to their expectation. For the entropy of entanglement, this has the counterintuitive consequence that there exist large subspaces in which all pure states are close to maximally entangled. This, in turn, implies the existence of mixed states with entanglement of formation near that of a maximally entangled state, but with negligible quantum mutual information and, therefore, negligible distillable entanglement, secret key, and common randomness. It also implies a very strong locking effect for the entanglement of formation: its value can jump from maximal to near zero by tracing over a number of qubits negligible compared to the size of the total system. Furthermore, such properties are generic. Similar phenomena are observed for random multiparty states, leading us to speculate on the possibility that the theory of entanglement is much simplified when restricted to asymptotically generic states. Further consequences of our results include a complete derandomization of the protocol for universal superdense coding of quantum states.