Rhodium Pyrazolate Complexes as Potential CVD Precursors

Reaction of 3,5-(CF3)(2)PzLi with [Rh(mu-Cl)(eta(2)-C2H4)(2)](2) or [Rh(mu-Cl)(PMe3)(2)](2) in Et2O gave the dinuclear complexes [Rh(eta(2)-C2H4)(2)(mu-3,5-(CF3)(2)-Pz)](2) (1) and [Rh-2(mu-Cl)(mu-3,5-(CF3)(2)-Pz) (PMe3)(4)] (2) respectively (3,5-(CF3)(2)Pz = bis-trifluoromethyl pyrazolate). Reaction of PMe3 with [Rh(COD)(mu-3,5-(CF3)(2)-Pz)](2) in toluene gave [Rh(3,5-(CF3)(2)-Pz)(PMe3)(3)] (3). Reaction of 1 and 3 in toluene (1 : 4) gave moderate yields of the dinuclear complex [Rh(PMe3)(2)(mu-3,5-(CF3)(2)-Pz)](2) (4). Reaction of 3,5-(CF3)(2)PzLi with [Rh(PMe3)(4)]Cl in Et2O gave the ionic complex [Rh(PMe3)(4)][3,5-(CF3)(2)-Pz] (5). Two of the complexes, 1 and 3, were studied for use as CVD precursors. Polycrystalline thin films of rhodium (fcc-Rh) and metastable-amorphous films of rhodium phosphide (Rh2P) were grown from 1 and 3 respectively at 170 and 130 degrees C, 0.3 mmHg in a hot wall reactor using Ar as the carrier gas (5 cc min(-1)). Thin films of amorphous rhodium and rhodium phosphide (Rh2P) were grown from 1 and 3 at 170 and 130 degrees C respectively at 0.3 mmHg in a hot wall reactor using H-2 as the carrier gas (7 cc min(-1)).Welch Foundation F-816Petroleum Research Fund 47014-ACSNSF 0741973Chemistr

Cavitation of the Ghon focus in an HIV-infected infant who acquired tuberculosis after the initiation of HAART

Tuberculosis immune reconstitution inflammatory syndrome (IRIS) may present as new or worsening cavitation. We present an HIV-infected infant in whom TB infection and subsequent cavitation of the Ghon focus appeared to coincide with immune reconstitution due to highly active antiretroviral therapy (HAART). TB-IRIS in response to infection that occurs after starting HAART has not previously been described

Immune reconstitution inflammatory syndrome in children

Paradoxical deterioration due to immune reconstitution inflammatory syndrome (IRIS) occurs in up to 21% of children initiating antiretroviral therapy. Mycobacterial diseases are the most common, with BCG-vaccine adenitis predominating in infants and Mycobacterium tuberculosis (TB) in older children. The difficulty of diagnosing TB in HIV-infected children and the increasing risk of drug-resistant TB complicate the diagnosis and  management of both paradoxical IRIS and post-antiretroviral therapy TB. History and clinical assessment remain key strategies in the management of these infants and children. There are no prospective studies investigating diagnostic criteria and therapeutic strategies in children

Virological response without CD4 recovery

The objective of antiretroviral therapy (ART) is to suppress viral replication so that immune restoration can occur. Failure of immune restoration is usually associated with poor virological suppression. In children a good immunological and clinical response to ART is often achieved despite incomplete viral suppression. However, we have recently managed a number of children in whom immune restoration did not occur despite excellent virological suppression. We present a case, discuss possible causes and speculate on the appropriate course of action. Southern African Journal of HIV Medicine Vol. 7 (3) 2006: pp. 45-4

The giant radio galaxy 8C0821+695 and its environment

We present new VLA and Effelsberg observations of the radio galaxy 8C0821+695. We have obtained detailed images in total intensity and polarization of this 2 Mpc sized giant. The magnetic field has a configuration predominantly parallel to the source main axis. We observe Faraday rotation at low frequencies, most probably produced by an ionized medium external to the radio source. The spectral index distribution is that typical of FR II radio galaxies, with spectral indices gradually steepening from the source extremes towards the core. Modeling the spectrum in the lobes using standard synchrotron loss models yields the spectral age of the source and the mean velocity of the jet-head with respect to the lobe material. The existence of a possible backflow in the lobe is considered to relate spectral with dynamical determinations of the age and the velocity with respect to the external medium. Through a very simple model, we obtain a physical characterization of the jets and the external medium in which the radio galaxy expands. The results in 8C0821+695 are consistent with a relativistic jet nourishing the lobes which expand in a hot, low density halo. We infer a deceleration of the source expansion velocity which we explain through a progressive increase in the hot-spot size.Comment: 11 pages; 8 figures; accepted in A&

Algebraic treatment of PT\mathcal{PT}-symmetric coupled oscillators

The purpose of this paper is the discussion of a pair of coupled linear oscillators that has recently been proposed as a model of a system of two optical resonators. By means of an algebraic approach we show that the frequencies of the classical and quantum-mechanical interpretations of the optical phenomenon are exactly the same. Consequently, if the classical frequencies are real, then the quantum-mechanical eigenvalues are also real

The Variability of Polarized Radiation from Sgr A*

Sgr A* is variable at radio and submillimeter wavelengths on hourly time scales showing time delays between the peaks of flare emission as well as linearly polarized emission at millimeter and sub-mm wavelengths. To determine the polarization characteristics of this variable source at radio frequencies, we present VLA observations of Sgr A* and report the detection of polarized emission at a level of 0.77\pm0.01% and 0.2\pm0.01% at 43 and 22 GHz, respectively. The change in the time averaged polarization angle between 22 and 43 GHz corresponds to a RM of -2.5\pm0.6 x10^3 rad m{-2} with no phase wrapping (or \sim 5x10^4 rad m^2 with 2\pi phase wrap). We also note a rise and fall time scale of 1.5 -- 2 hours in the total polarized intensity. The light curves of the degree of linearly polarized emission suggests a a correlation with the variability of the total intensity at 43 GHz. The available polarization data at radio and sub-mm wavelengths suggest that the rotation measure decreases with decreasing frequency. This frequency dependence, and observed changes in polarization angle during flare events, may be caused by the reduction in rotation measure associated with the expansion of synchrotron-emitting blobs.Comment: 11 pages, 3 figures, ApJL (in press

Compact Radio Sources within 30" of Sgr A*: Proper Motions, Stellar Winds and the Accretion Rate onto Sgr A*

Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR counterparts, as well as 44 proplyd candidates within 30" of Sgr A*. Radio observations obtained in 2011 and 2014 have been used to derive proper motions of eight young stars near Sgr A*. The accuracy of proper motion estimates based on near-IR observations by Lu et al. and Paumard et al. have been investigated by using their proper motions to predict the 2014 epoch positions of near-IR stars and comparing the predicted positions with those of radio counterparts in the 2014 radio observations. Predicted positions from Lu et al. show an rms scatter of 6 mas relative to the radio positions, while those from Paumard et al. show rms residuals of 20 mas, which is mainly due to uncertainties in the IR-based proper motions. Under the assumption of homogeneous ionized winds, we also determine the mass-loss rates of 11 radio stars, finding rates that are on average $\sim$2 times smaller than those determined from model atmosphere calculations and near-IR data. Clumpiness of ionized winds would reduce the mass loss rate of WR and O stars by additional factors of 3 and 10, respectively. One important implication of this is a reduction in the expected mass accretion rate onto Sgr A* from stellar winds by nearly an order of magnitude to a value of few$\times10^{-7}$ \msol\ yr$^{-1}$. Finally, we present the positions of 318 compact 34.5 GHz radio sources within 30\arcs\ of Sgr A*. At least 45 of these have stellar counterparts in the near-IR $K_s$ (2.18 $\mu$m) and $L'$ (3.8$\mu$m) bands.Comment: 30 pages, 4 figures, ApJ (in press