Synthesis and reactivity of 5-polyfluoroalkyl-5-deazaalloxazines

Reaction of 6-arylamino-1,3-dialkyluracils with anhydrides of polyfluorocarboxylic acids in the presence of pyridine and subsequent cyclization with concentrated H2SO4 gave the corresponding 1,3-dialkyl-5-(polyfluoroalkyl)pyrimido[4,5-b]quinoline-2,4(1H,3H)-diones (5-polyfluoroalkyl-5-deazaalloxazines). The reactivity of these compounds towards nucleophilic reagents, such as sodium cyanoborohydride, acetophenone, nitromethane, potassium cyanide, indole and p-thiocresol, as well as Suzuki and Sonogashira couplings are described. The nucleophilic addition takes place at the 5-position of the 5-deazaalloxazine system and is in many cases irreversible to give 5,10-dihydropyrimido[4,5-b]quinoline-2,4(1H,3H)-dione derivatives in good to excellent yields.© 2013 The Royal Society of Chemistry

All-optical dc nanotesla magnetometry using silicon vacancy fine structure in isotopically purified silicon carbide

We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-$^{28}$SiC) and find extra terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which are otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity of 87 nT Hz$^{-1/2}$ within a volume of $3 \times 10^{-7}$ mm$^{3}$ at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radiofrequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm$^{3}$ the projection noise limit is below 100 fT Hz$^{-1/2}$.Comment: 12 pages, 6 figures; additional experimental data and an extended theoretical analysis are added in the second versio

Elemental bio-imaging of thorium, uranium, and plutonium in tissues from occupationally exposed former nuclear workers

Internal exposure from naturally occurring radionuclides (including the inhaled long-lived actinides 232Th and 238U) is a component of the ubiquitous background radiation dose (National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States; NCRP Report No. 160; NCRP: Bethesda, MD, 2009). It is of interest to compare the concentration distribution of these natural ?-emitters in the lungs and respiratory lymph nodes with those resulting from occupational exposure, including exposure to anthropogenic plutonium and depleted and enriched uranium. This study examines the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) to quantifying and visualizing the mass distribution of uranium and thorium isotopes from both occupational and natural background exposure in human respiratory tissues and, for the first time, extends this application to the direct imaging of plutonium isotopes. Sections of lymphatic and lung tissues taken from deceased former nuclear workers with a known history of occupational exposure to specific actinide elements (uranium, plutonium, or americium) were analyzed by LA-ICPMS. Using a previously developed LA-ICPMS protocol for elemental bio-imaging of trace elements in human tissue and a new software tool, we generated images of thorium (232Th), uranium (235U and 238U), and plutonium (239Pu and 240Pu) mass distributions in sections of tissue. We used a laboratory-produced matrix-matched standard to quantify the 232Th, 235U, and 238U concentrations. The plutonium isotopes 239Pu and 240Pu were detected by LA-ICPMS in 65 ?m diameter localized regions of both a paratracheal lymph node and a sample of lung tissue from a person who was occupationally exposed to refractory plutonium (plutonium dioxide). The average (overall) 239Pu concentration in the lymph node was 39.2 ng/g, measured by high purity germanium (HPGe) ?-spectrometry (Lynch, T. P.; Tolmachev, S. Y.; James, A. C. Radiat. Prot. Dosim. 2009, 134, 94?101). Localized mass concentrations of thorium (232Th) and uranium (238U) in lymph node tissue from a person not occupationally exposed to these elements (chronic natural background inhalation exposure) ranged up to 400 and 375 ng/g, respectively. In lung samples of occupationally nonexposed to thorium and uranium workers, 232Th and 238U concentrations ranged up to 200 and 170 ng/g, respectively. In a person occupationally exposed to air-oxidized uranium metal (Adley, F. E.; Gill, W. E.; Scott, R. H. Study of atmospheric contaminiation in the melt plant buiding. HW-23352(Rev.); United States Atomic Energy Commission: Oakridge, TN, 1952, p 1?97), the maximum 235U and 238U isotopic mass concentrations in a lymph node, measured at higher resolution (with a 30 ?m laser spot diameter), were 70 and 8500 ng/g, respectively. The ratio of these simultaneously measured mass concentrations signifies natural uranium. The current technique was not sufficiently sensitive, even with a 65 ?m laser spot diameter, to detect 241Am (at an overall tissue concentration of 0.024 ng/g, i.e., 3 Bq/g). © 2010 American Chemical Society

Effect of cerebrolysin on motor function restoration during medical rehabilitation

Ischemic stroke (IS) is characterized by high prevalence, mortality, and disability rates. Therapy aimed to correct one biochemical or molecular stage of ischemic cell injury fails to treat stroke, suggesting that it is necessary to study multimodality therapy affecting several related pathophysiological components.The paper gives the January 2016 results of the randomized placebo-controlled multicenter study CARS that demonstrates the positive effect of cerebrolysin versus placebo according to the primary efficiency criterion, the Action Research Arm Test (ARAT) scale, and total outcome 90 days after disease onset. The investigation enrolled mainly patients with moderate or severe IS (the mean National Institutes of Health Stroke Scale score was 9 at baseline).The specific features of the CARS study versus those of other clinical trials of neuroprotectors were the initial planning of narrower end criteria of efficiency (arm motor function recovery whereas the major goal of many investigations was to reduce mortality rates), as well as a standardized rehabilitation program in both treatment groups. Such investigations did not previously take into account the nature and volume of rehabilitation measures although the latter may have a substantial impact on the outcome of stroke.The CARS study is the first among the previously conducted clinical trials of neuroprotectors, which has attained the primary objective (to restore motor function), which opens up fresh opportunities for the medical support of rehabilitation measures in patients with IS

Efficient synthesis of novel thieno[3,2-b]-, [2,3-c]- and [3,2-c]pyridones by Sonogashira coupling of bromothiophenes with terminal alkynes and subsequent intramolecular C-N bond-forming reaction

The coupling of bromothiophenes with terminal alkynes using triethylamine or diisopropyl amine under Sonogashira conditions (PdCl2(PPh 3)2, CuI) followed by subsequent addition of amines or ammonium to the intermediate thienyl acetylenes represents a novel access to a wide range of thieno[3,2-b]-, [2,3-c]-, and [3,2-c]pyridones under basic conditions and in excellent yields. © 2013 Elsevier Ltd. All rights reserved

Specific features of reperfusion therapy for vertebrobasilar ischemic stroke

Ischemic stroke in the vertebrobasilar system (VBS) is characterized by the high rates of death and disability; reperfusion therapy in patients with a lesion focus in the VBS is safe and effective beyond the 4.5-hour therapeutic window. Actively developed current methods for the endovascular treatment of acute ischemic stroke enable one to increase recanalization rates and hence to improve the degree of functional recovery in this group of patients. Considering that there are no significant differences in the outcomes of systemic and selective thrombolytic therapy in patients with occlusion of the basilar arteries, the urgent problem is to increase the time from the onset of the disease to reperfusion therapy, therefore combined reperfusion therapy may be an optimal option. This approach would make it possible to initiate the therapy in a shorter period of time and to use the advantages of both reperfusion techniques. Intravenous thrombolysis as the rapidest and technically simplest method may be performed in the first step of therapy in the clinics unequipped with an X-ray surgical service, with the patient being further transported to a specialized endovascular center if the intravenous injection of a thrombolytic agent has no effect. Taking into account the fact that reperfusion therapy may be performed in patients with vertebrobasilar stroke in the wider therapeutic window, a similar organizational chart with multistep therapy for this disease might become the treatment of choice

Influence of the working fluid thermophysical parameters variation on the gas turbine cycle performance

The thermodynamic analysis of effect of the syngas combustion products (working fluid) thermophysical parameters variation on the economic and energy parameters of the gas turbine cycle is described. The thermodynamic analysis of Brayton cycle performance on various compositions of working fluid within a selected range of control parameters variation is presented. A gas turbine working fluid database was generated based on the analysis of flow diagram and operating regime of the production and design alternative gas-fired CCPP. The relationship between the cycle thermodynamic (pressure and temperature) and thermophysical parameters of the working fluid, which ensures gas turbine cycle maximum work, is derived analytically and supported by the well-known actual data. © Published under licence by IOP Publishing Ltd.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006

Positron annihilation spectroscopy of vacancy-type defects hierarchy in submicrocrystalline nickel during annealing

Positron annihilation and X-ray diffraction analysis have been used to study submicrocrystalline nickel samples prepared by equal channel angular pressing. In the as-prepared samples the positrons are trapped at dislocation-type defects and in vacancy clusters that can include up to 5 vacancies. The study has revealed that the main positron trap centers at the annealing temperature of deltaT= 20°C-180°C are low-angle boundaries enriched by impurities. At deltaT = 180°C-360°C, the trap centers are low-angle boundaries providing the grain growth due to recrystallization in-situ