Bulgarian Academy of Sciences

About: Bulgarian Academy of Sciences is a government organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Catalysis & Coupling constant. The organization has 17989 authors who have published 36276 publications receiving 642820 citations. The organization is also known as: Bulgarian Academy of Sciences，簡稱：BAS & Balgarska Akademiya na Naukite.

Event activity dependence of Υ(nS) production in √sNN = 5.02 TeV pPb and √s = 2.76 TeV pp collisions

Abstract: The production of Y(1S), Y(2S), and Y(3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 inverse nanobarns (pPb) and 5.4 inverse picobarns (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval abs(y[CM]) , are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, Y(nS)/Y(1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. The event activity integrated double ratios, [Y(nS)/Y(1S)][pPb] / [Y(nS)/Y(1S)][pp], are also measured and found to be 0.83 +/- 0.05 (stat.) +/- 0.05 (syst.) and 0.71 +/- 0.08 (stat.) +/- 0.09 (syst.) for Y(2S) and Y(3S), respectively.

Induced crystallization porosity and properties of sintereds diopside and wollastonite glass-ceramics

Abstract: A diopside (CaO·MgO·2SiO 2 ) and wollastonite (CaO·SiO 2 ) glass-ceramics, forming ∼60% crystal phase and ∼40% albite-like (Na 2 O·Al 2 O 3 ·6SiO 2 ) residual glass were studied Two other diopside glass-ceramics with higher Na 2 O and Al 2 O 3 content were also investigated The phase formation was estimated by DTA, XRD and pycnometry, while the densification process was evaluated by porosity variations, dilatometry and SEM observations The bending strength, Young modulus and coefficient of thermal expansion of the glass-ceramics were also measured and discussed The compositions were characterized by a good sinter-ability and surface crystallization and, due to the different volume variation of diopside and wollastonite during the crystallization, diverse amounts of intragranular crystallization induced porosity , P CR , were formed in the glass-ceramics Notwithstanding the higher porosity, the diopside glass-ceramics have better mechanical properties than wollastonite one At the same time, despite of the different residual glass compositions and the diverse coefficients of thermal expansion, all diopside materials have comparable bending strength and Young modulus The obtained diopside sintered glass-ceramics are characterized by significant porosity of 10–12 vol%, high amount of residual glass (about 40%), large initial particles ( P CR formation

Effect of water on the reduction of NOx with propane on Fe‐ZSM‐5. An FTIR mechanistic study

Abstract: Adsorption of NO on Fe‐ZSM‐5 leads to formation of Fen+–NO (n = 2 or 3) species (1880 cm-1), Fe2+(NO)2 complexes (1920 and 1835 cm-1) and NO+ (2133 cm-1). Water strongly suppresses the formation of NO+ and Fen+(NO)2 and more slightly the formation of Fen+ –NO. Introduction of oxygen to NO converts the nitrosyls into surface nitrates (1620 and 1575 cm-1) and this process is almost unaffected by water. The nitrates are thermally stable up to ca. 300°C, but readily interact with propane at 200°C, thus forming surface C–H–N–O deposit (bands in the 1700–1300 cm-1 region). Here again, water does not hinder the process. The C–H–N–O deposit is relatively inert (it does not interact with NO or NO + O2 at ambient temperature) but, at temperatures higher than 250 °C, it is decomposed to NCO- species (bands at 2215 (Fe–NCO) and 2256 cm-1 (Al–NCO)). In the presence of water, however, the Fe–NCO species only are formed. At ambient temperature the NCO- species are inert towards NO and O2, but easily react with a NO + O2 mixture. The mechanism of the selective catalytic reduction of nitrogen oxides on Fe‐ZSM‐5 and the effect of water on the process are discussed.