Magnesium-zinc reduction is effective in preparation of metals

Uranium, thorium, and plutonium are effectively prepared by magnesium-zinc reduction, using uranium oxides, thorium dioxide, and plutonium dioxide as starting materials. This technique is also useful in performing reduction of metals such as zirconium and titanium

Decompressive Laminectomy in the Management of Spinal Epidural Metastases

In a series of 60 patients undergoing decompression laminectomy for metastatic malignancy, the median survival was 3.3 months with 11 patients (18%) living for at least one year and ambulating during part of this survival period. Forty-three per cent of the group were able to ambulate for at least some period postoperatively. If a patient could ambulate preoperatively he had a two-thirds chance of ambulating afterwards; conversely, if he could not ambulate preoperatively. he had a two-thirds chance of not ambulating postoperatively. The lymphoma group had the best prognosis. Long lesions and highly vascular tumors fared poorly. Paralysis (as defined by inability to ambulate) had developed with great rapidity in half of the patients unable to walk prior to operation. We postulate that this was caused by infarction of the spinal cord. A plea is made for early diagnosis and effective removal of these lesions before signs of cord compression are evident, and especially before the patient loses his ability to walk

Measurements of volatile organic compounds using proton transfer reaction ? mass spectrometry during the MILAGRO 2006 Campaign

International audienceVolatile organic compounds (VOCs) were measured by proton transfer reaction ? mass spectrometry (PTR-MS) on a rooftop in the urban mixed residential and industrial area North Northeast of downtown Mexico City as part of the Megacity Initiative ? Local and Global Research Observations (MILAGRO) 2006 field campaign. Thirty eight individual masses were monitored during the campaign and many species were quantified including methanol, acetaldehyde, toluene, the sum of C2 benzenes, the sum of C3 benzenes, acetone, isoprene, benzene, and ethyl acetate. The VOC measurements were analyzed to gain a better understanding of the type of VOCs present in this region of the MCMA, their diurnal patterns and their origins. Diurnal profiles of weekday and weekend/holiday aromatic VOC concentrations show the influence of vehicular traffic during the morning rush hours and during the afternoon hours. Plumes including of elevated toluene as high as 216 parts per billion (ppb) and ethyl acetate as high as 183 ppb were frequently observed during the late night and early morning hours, indicating the probability of significant industrial sources of the two compounds in the region. Wind fields during those peak episodes revealed no specific direction for the majority of the toluene plumes but the ethyl acetate plumes arrived at the site when winds were from the Southwest or West. The PTR-MS measurements combined with other VOC measuring techniques at the field site as well as VOC measurements conducted in other areas of the Mexico City Metropolitan Area (MCMA) will help to develop a better understanding of the spatial pattern of VOCs and its variability in the MCMA

Using t -> b \bar{b} c to Search for New Physics

We consider new-physics (NP) contributions to the decay t -> b \bar{b} c. We parameterize the NP couplings by an effective Lagrangian consisting of 10 Lorentz structures. We show that the presence of NP can be detected through the measurement of the partial width. A partial identification of the NP can be achieved through the measurements of a forward-backward-like asymmetry, a top-quark-spin-dependent asymmetry, the partial rate asymmetry, and a triple-product asymmetry. These observables, which vanish in the standard model, can all take values in the 10-20% range in the presence of NP. Since |V_{tb}V_{cb}| \simeq |V_{ts} V_{cs}|, most of our results also hold, with small changes, for t -> s \bar{s} c.Comment: 25 pages, 7 figures; made a few small corrections, results unchange

Synthesis and luminescent properties of hetero-bimetallic and hetero-trimetallic Ru( ii )/Au( i ) or Ir( iii )/Au( i ) complexes

A series of Ru(ii) and Ir(iii) based photoluminescent complexes were synthesised that incorporate an ancillary 2,2′-bipyridine ligand adorned with either one or two pendant N-methyl imidazolium groups. These complexes have been fully characterised by an array of spectroscopic and analytical techniques. One Ir(iii) example was unequivocally structurally characterised in the solid state using single crystal X-ray diffraction confirming the proposed formulation and coordination sphere. These complexes were then transformed into their heterometallic, Au(i)-containing, analogues in two steps to yield either bi- or trimetallic complexes that integrate {Au(PPh3)}+ units. X-ray diffraction was used to corroborate the solid state structure of the hetero bimetallic complex, based upon a Ru(ii)–Au(i) species. The heterometallic complexes all displayed red photoluminescent features (λem = 616–629 nm) that were consistent with the parent Ru(ii) or Ir(iii) lumophores in each case. The modulation of the emission from the Ru(ii)–Au(i) complexes was much more strongly evident than for the Ir(iii)–Au(i) analogues, which is ascribed to the inherent differences in the specific triplet excited state character of the emitting states within each heterometallic species

Measurements of Volatile Organic Compounds Using Proton Transfer Reaction - Mass Spectrometry during the MILAGRO 2006 Campaign

Volatile organic compounds (VOCs) were measured by proton transfer reaction – mass spectrometry (PTR-MS) on a rooftop in the urban mixed residential and industrial area North Northeast of downtown Mexico City as part of the Megacity Initiative – Local and Global Research Observations (MILAGRO) 2006 field campaign. Thirty eight individual masses were monitored during the campaign and many species were quantified including methanol, acetaldehyde, toluene, the sum of C2 benzenes, the sum of C3 benzenes, acetone, isoprene, benzene, and ethyl acetate. The VOC measurements were analyzed to gain a better understanding of the type of VOCs present in the MCMA, their diurnal patterns, and their origins. Diurnal profiles of weekday and weekend/holiday aromatic VOC concentrations showed the influence of vehicular traffic during the morning rush hours and during the afternoon hours. Plumes including elevated toluene as high as 216 parts per billion (ppb) and ethyl acetate as high as 183 ppb were frequently observed during the late night and early morning hours, indicating the possibility of significant industrial sources of the two compounds in the region. Wind fields during those peak episodes revealed no specific direction for the majority of the toluene plumes but the ethyl acetate plumes arrived at the site when winds were from the Southwest or West. The PTR-MS measurements combined with other VOC measuring techniques at the field site as well as VOC measurements conducted in other areas of the Mexico City Metropolitan Area (MCMA) will help to develop a better understanding of the spatial pattern of VOCs and its variability in the MCMA. Atmos. Chem. Phys., 9, 467–481, 2009.Robert A. Welch Foundation (Grant A-1417)Texas A & M University. Center for Atmospheric Chemistry and EnvironmentNational Science Foundation (U.S.) (ATM-0528227

Polycationic Ru(II) luminophores: syntheses, photophysics, and application in electrostatically driven sensitization of lanthanide luminescence

A series of photoluminescent Ru(II) polypyridine complexes have been synthesized in a manner that varies the extent of the cationic charge. Two ligand systems (L1 and L2), based upon 2,2′-bipyridine (bipy) mono- or difunctionalized at the 5- or 5,5′-positions using N-methylimidazolium groups, were utilized. The resulting Ru(II) species therefore carried +3, +4, +6, and +8 complex moieties based on a [Ru(bipy)3]2+ core. Tetra-cationic [Ru(bipy)2(L2)][PF6]4 was characterized using XRD, revealing H-bonding interactions between two of the counteranions and the cationic unit. The ground-state features of the complexes were found to closely resemble those of the parent unfunctionalized [Ru(bipy)3]2+ complex. In contrast, the excited state properties produce a variation in emission maxima, including a bathochromic 44 nm shift of the 3MLCT band for the tetra-cationic complex; interestingly, further increases in overall charge to +6 and +8 produced a hypsochromic shift in the 3MLCT band. Supporting DFT calculations suggest that the trend in emission behavior may, in part, be due to the precise nature of the LUMO and its localization. The utility of a photoactive polycationic Ru(II) complex was then demonstrated through the sensitization of a polyanionic Yb(III) complex in free solution. The study shows that electrostatically driven ion pairing is sufficient to facilitate energy transfer between the 3MLCT donor state of the Ru(II) complex and the accepting 2F5/2 excited state of Yb(III)