Splitting for subalgebras of tensor products

We prove splitting results for subalgebras of tensor products of operator algebras. In particular, any -algebra s.t. is a tensor product provided is simple and nuclear.

     

A note on spectral triples and quasidiagonality

Spectral triples (of compact type) are constructed on arbitrary separable quasidiagonal C^*$C^{*}$-algebras. On the other hand an example of a spectral triple on a non-quasidiagonal algebra is presented.     

Minimal Cuntz-Krieger dilations and representations of Cuntz-Krieger algebras

Given a contractive tuple of Hilbert space operators satisfying certainA-relations we show that there exists a unique minimal dilation to generators of Cuntz-Krieger algebras or its extension by compact operators. This Cuntz-Krieger dilation can be obtained from the classical minimal isometric dilation as a certain maximalA-relation piece. We define a maximal piece more generally for a finite set of polynomials inn noncommuting variables. We classify all representations of Cuntz-Krieger algebrasO _A obtained from dilations of commuting tuples satisfyingA-relations. The universal properties of the minimal Cuntz-Krieger dilation and the WOT-closed algebra generated by it is studied in terms of invariant subspaces.     

Tunable, high-power, narrow-band picosecond IR radiation by optical parametric amplification in KTP

We report on an optical parametric amplifier (OPA) based on two potassium titanyl phosphate (KTP) crystals in a walk-off compensating geometry. An Nd:YLF regenerative amplifier at a 1-kHz repetition rate serves as the pump source. The seed beam is delivered by a synchronously pumped frequency-stabilized optical parametric oscillator (OPO) based on periodically poled lithium niobate (PPLN). At pump intensities of about 7 GW/cm² large amplification factors of more than 10⁴ were achieved, resulting in pulse energies of more than 450 μJ and 350 μJ for the signal and idler pulses, respectively, at a 1-kHz repetition rate. In the saturation regime the time–bandwidth product increases from two to three times the Fourier limit, with a pulse duration of 105 ps and a bandwidth of 12.7 GHz at the highest intensities employed. Received: 2 November 2001 / Published online: 14 March 2002     

Superconducting linear accelerator system for NSC

This paper reports the construction of a superconducting linear accelerator as a booster to the 15 UD Pelletron accelerator at Nuclear Science Centre, New Delhi. The LINAC will use superconducting niobium quarter wave resonators as the accelerating element. Construction of the linear accelerator has progressed sufficiently. Details of the entire accelerator system including the cryogenics facility, RF electronics development, facilities for fabricating niobium resonators indigenously, and present status of the project are presented.     

Condensation of bis(β-alaninato)copper(II) with formaldehyde and ammonia

Various complexes have been prepared by the template condensation of -amino acids with formaldehyde or acetaldehyde in the presence of metal ions(^1–5). In particular, glycine has received much attention(^1–4). For example, (3N, 7N-1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-diacetato nickel(II) (1) has been prepared by condensing bis(glycinato)nickel(II) dihydrate with formaldehyde and ammonia at pH 8.5⁴. More recently⁵, complex (2) has been prepared by condensing bis(L-alaninato)copper(II) with formaldehyde and ammonia. These reactions are interesting for the following reasons:

Spectral and magnetic investigations on some binuclear oxovanadium compounds

Several binuclear oxovanadium compounds of binucleating ligands are synthesised and investigated by magnetic, spectral and esr methods. The experimental results show that there is weak exchange interaction mediated by the bridging organic molecules between the vanadium centres. The magnitude of this interaction is more than that observed in the corresponding copper(II) dimers. The possible reason for this is discussed.     

Continuously tunable VUV radiation (129–210 nm) by anti-Stokes Raman scattering in cooled H2

The generation of tunable vacuum ultraviolet radiation by anti-Stokes Raman scattering of tunable ultraviolet dye-laser radiation in cold hydrogen has been investigated. The scattering efficiency of XeCl laser and Nd:YAG laser pumped commercial dye lasers and the influence of different beam profiles has been studied. Up to 12 anti-Stokes orders down to 129 nm were observed with output powers between about 20 kW at =191 nm and somewhat less than 100 W at =129 nm. The efficiency of transversely pumped lasers with an intensity peaked in the center of the beam profile was found to be higher than doughnut shaped intensity distributions. The cooling of the active gas to liquid nitrogen temperatures improved the output pulse energies 3 to 5 times on average. It was found that this intensity increase was caused mainly by the narrowing of the Raman linewidth upon cooling.     

Pyrroloquinolines,a New Platform for Developing Organic Photosensitizers: When Synthetic Methodology Meets Photophysics†

New molecular architectures with triplet sensitization properties can have a big impact on photochemistry and photobiology. In their recent work, de Bonfils et al. have tackled this challenge in a very systematic way using a powerful synthetic strategy. This consists of an elegant yet practical organocatalyzed cyclization/oxidation rearrangement sequence which they now apply to the synthesis of pyrroloquinolines, a new scaffold for photosensitizers. However, beyond this new class of compounds, the strategy has potential to produce a myriad of compact organic chromophores with promising photoinduced intersystem crossing properties. The study therefore provides interesting clues to serve the rational design of biocompatible molecular photosensitizers but also raises puzzling questions on the intriguing excited state reactivity of these molecular architectures.     

In vivo evaluation and in vitro metabolism of leuprolide in mice--mass spectrometry-based biomarker measurement for efficacy and toxicity

The study of pharmacologically active peptides is central for the understanding of cancer and the development of novel therapeutic approaches. In this context, both qualitative and quantitative determination of bioactive peptides in biological fluids/tissues and their effect on endogenous factors (e.g. hormones) are of great importance. A mass spectrometry-based approach was developed and applied towards the measurement of leuprolide, a peptide drug for the treatment of prostate cancer, in mouse plasma. High-pressure liquid chromatography coupled to a hybrid quadrupole linear ion trap (QqLIT) mass spectrometer, a platform that combines the benefits of triple QqLIT instruments, was employed for the study. Using the described methodology, we established that picomolar concentrations of leuprolide could be measured in mouse plasma (limit of quantification of 0.1 ng/ml). In order to optimize pharmacokinetic properties of analogs of leuprolide, a facile in vivo mouse model was developed and leuprolide concentrations were determined in mouse plasma following intraperitoneal administration. In the same animal model, we demonstrated the versatility of the described MS-based approach by the determination of plasma concentrations of testosterone, an established biomarker for the treatment of prostate cancer. Following dosing with leuprolide, circulating testosterone was increased significantly in comparison to vehicle-treated mice. Finally, in vitro metabolism of leuprolide was evaluated by incubation of leuprolide with mouse kidney membranes, followed by identification of major metabolites by MS. Such studies provide the framework for future evaluation of novel leuprolide analogs with potential therapeutic advantages.