Energy loss distributions of 7 TeV protons channeled in a bent silicon crystals

The energy loss distributions of relativistic protons axially channeled through the bent <100> Si crystals, with the constant curvature radius, R = 50 m, are studied here. The proton energy is 7 TeV and the thickness of the crystal is varied from 1 mm to 5 mm, which corresponds to the reduced crystal thickness, L, from 2.1 to 10.6, respectively. The proton energy was chosen in accordance with the large hadron collider project, at the European Organization for Nuclear Research, in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated by the computer simulation method using the numerical solution of the proton equations of motion in the transverse plane. Dispersion of the proton scattering angle caused by its collisions with the crystal’s electrons was taken into account. [Projekat Ministarstva nauke Republike Srbije, br. III 45006

Influence of nuclear multiple scattering on axially channeled protons in a bent crystal

The influence of nuclear multiple scattering on axially channeled protons with an energy of 7 TeV through a bent Si crystal, is presented in this paper. The aims of the investigation are the processes correlated to the axial channeling, such as dechanneling, angular distributions and energy loss distribution. The data for these processes are generated via the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. In the simulations, the crystal thickness is varied from 1 to 5 mm while the bending angle is varied from 0 to 20 μrad. The increasing of the transverse energy of axially channeled protons is due to its multiple scattering by atomic strings and the bending dechanneling mechanism. The analysis of the generated data shows that in the cases we are considering, the dechanneling function, the energy loss spectra, and the angular distributions do not undergo to any significant changes when the effect of nuclear multiple scattering is included in the ion-atom interactions. © 2018, Vinca Inst Nuclear Sci. All rights reserved

Coordinated self-interference of wave packets: a new route towards classicality for structurally stable systems

This is a study of proton transmission through planar channels of tungsten, where a proton beam is treated as an ensemble of noninteracting wave packets. For this system, the structural stability manifests in an appearance of caustic lines, and as an equivalence of self-interference produced waveforms with canonical diffraction patterns. We will show that coordination between particle self-interference is an additional manifestation of the structural stability existing only in ensembles. The main focus of the analysis was on the ability of the coordination to produce classical structures. We have found that the structures produced by the self-interference are organized in a very different manner. The coordination can enhance or suppress the quantum aspects of the dynamics. This behavior is explained by distributions of inflection, undulation, and singular points of the ensemble phase function, and their bifurcations. We have shown that the coordination has a topological origin which allows classical and quantum levels of reality to exist simultaneously. The classical behavior of the ensemble emerges out of the quantum dynamics without a need for reduction of the quantum to the classical laws of motion

Quantum Rainbows in Positron Transmission through Carbon Nanotubes

Here we report the results of the theoretical investigation of the transmission of channeled positrons through various short chiral single walled carbon nanotubes (SWCNT). The main question answered by this study is “What are the manifestations of the rainbow effect in the channeling of quantum particles that happens during the channeling of classical particles?” To answer this question, the corresponding classical and quantum problems were solved in parallel, critically examined, and compared with each other. Positron energies were taken to be 1 MeV when the quantum approach was necessary. The continuum positron-nanotube potential was constructed from the thermally averaged Molière’s positron-carbon potential. In the classical approach, a positron beam is considered as an ensemble of noninteracting particles. In the quantum approach, it is considered as an ensemble of noninteracting wave packages. Distributions of transmitted positrons were constructed from the numerical solutions of Newton’s equation and the time-dependent Schrödinger equation. For the transmission of 1-MeV positrons through 200-nm long SWCNT (14; 4), in addition to the central maximum, the quantum angular distribution has a prominent peak pair (close to the classical rainbows) and two smaller peaks pairs. We have shown that even though the semiclassical approximation is not strictly applicable it is useful for explanation of the observed behavior. In vicinity of the most prominent peak, i.e., the primary rainbow peak, rays interfere constructively. On one of its sides, rays become complex, which explains the exponential decay of the probability density in that region. On the other side, the ray interference alternates between constructive and destructive, thus generating two observed supernumerary rainbow peaks. The developed model was then applied for the explanation of the angular distributions of 1-MeV positrons transmitting through 200 nm long (7, 3), (8, 5), (9, 7), (14, 4), (16, 5) and (17, 7) SWCNTs. It has been shown that this explains most but not all rainbow patterns. Therefore, a new method for the identification and classification of quantum rainbows was developed relying only on the morphological properties of the positron wave function amplitude and the phase function families. This led to a detailed explanation of the way the quantum rainbows are generated. All wave packets wrinkle due to their internal focusing in a mutually coordinated way and are concentrated near the position of the corresponding classical rainbow. This explanation is general and applicable to the investigations of quantum effects occurring in various other atomic collision processes

Spatial rainbows and catastrophes in transmission of protons through electrostatic octopole lens

This paper considers the transmission of the initial parallel proton beam with kinetic energy of 10 keV through the electrostatic oelopole lens. The spatial rainbows and corresponding proton distributions are calculated by using the infinite length approximation potential. Positive potentials of the lens electrodes are set to be 0.35 kV and 9 kV. It has been shown that by application of catastrophe theory, the generating function for mapping proton positions between entrance and exit transverse plains can be determined, giving accurate rainbow patterns for biasing potentials of 0.35 kV. © 2018; Vinca Inst Nuclear Sci. All rights reserved

Katalitička svojstva La1-ySryCr1-xRuxO3 perovskita u oksidaciji ugljenmonoksida

The oxidation of CO over La1-ySryCr1-xRuxO3 perovskite type oxides with y=0.3 and 0 £x £0.100 have been studied. X-ray fluorescence analysis confirmed that content of elements in the bulk corresponds to the established nominal perovskite stoichiometry, indicating that no significant oxidation of ruthenium into volatile polyvalent oxides with their consequent escape from the sample occurred in air up to the temperature of 1000 ºC. According to X-ray diffraction analysis, all samples achieved the perovskite hexagonal with the presence of some SrCrO4. X-ray photoelectron spectroscopy analysis of ruthenium samples shows higher Ru and Sr surface concentrations than in the bulk. The binding energy for Ru3p is virtually the same in all samples and consistent with that of Ru4+ (463.6.464.3eV). Kinetic studies were performed in a differential recycle reactor with a recycling ratio 80. The results show that substitution of Ru4+ for Cr3+ in La1-ySryCrO3 leads to a significant increase in both the activity and the activation energy. The global CO oxidation rate, referred on the BET surface area, correlates with the surface Ru4+ atomic concentration. Hence, the activity reflect the surface enrichment in ruthenium. Moreover, an identical apparent activation energy E = 93 kJ/mol and the same specific rate per ruthenium surface ion were obtained for samples with a Ru content x ‡ 0.05 suggest that exposed Ru4+ ions mainly participate in the reaction.Predmet ovog rada je ispitivanje katalitičke aktivnosti mešanih oksida La1-ySryCr1-xRuxO3 strukture perovskita sa y = 0,3 i 0,025 £ x £ 0,100 u oksidaciji ugljenmonoksida. Visoka saglasnost unete i X-fluoroscentnom analizom nađene količine rutenijuma u uzorcima kalcinisanim na 100ºC u vazduhu, ukazuje na to da nije došlo do značajne oksidacije Ru do isparljivih polivalentnih oksida i njihovog otparavanja iz uzorka. Analiza difraktograma X-zraka je pokazala da je u svim uzorcima pored perovskitne faze prisutan i manji udeo SrCrO4 faze. Koncentracije Sr i Ru u površinskim slojevima, izračunate iz X-fotoelektronske spektroskopije, su veće u odnosu na njihovu koncentraciju u masi. Energija veze Ru3p je ista za sve uzorke i karakteristična je za Ru4+. Kinetika oksidacije ugljenmonoksida ispitivana je u diferencijalnom recirkulacionom reaktoru. Rezultati pokazuju da delimična zamena Cr3+ sa Ru4+ u La1-ySryCrO3 dovodi do znatnog porasta aktivnosti i energije aktivacije. Ukupna brzina oksidacija CO, obračunata po jedinici specifične površine, je skoro proporcionalna porastu atomske koncentracije Ru4+ na površini uzorka, odnosno Rux ‡ 0,05 dobivena je ista prividna energija aktivacije od E = 93 kJ/mol i ista specifična brzina oksidacije po površinskom jonu Ru4+,što ukazuje na to da su joni Ru4+ izloženi i da oni prevashodno učestvuju u reakciji

Adsorptive removal of anti-epileptic drug - carbamazepine by activated carbon

This work describes the adsorption process of one of the most dominant pharmaceuticals detected in water sources, carbamazepine (CBZ), from aqueous solutions with commercially available activated carbon (AC). Adsorption studies were performed on powdered activated carbon Norit SA2, in ambient temperature, on pH value between 2 – 10, with different masses of adsorbent (6 – 20 mg), time intervals (5 – 60 min). The CBZ adsorption is explained by chemisorption which involves chemical reaction between surface and adsorbate. The results show that commercial activated carbon Norit SA2 can be applied in the process of adsorption for the purpose of removing carbamazepine from aqueous solution

Electrochemical Behavior of H3pw12o40/Acid-Activated Bentonite Powders

Electrochemical behavior of 12-tungstophosphoric acid (HPW)/acid-activated bentonite (AAB) powders with various loadings of HPW was investigated. The physicochemical properties of the prepared powders were examined by X-ray powder diffraction, nitrogen adsorption-desorption isotherms, atomic force microscopy and cyclic voltammetry measurements. The results indicated that the prepared powders are composed mainly of oriented domains of large rock blocks, probably resulting from a preferable deposition of bentonite particles having a face-to-face interaction. The particles had a mainly disordered mesoporous structure with a pore volume that varied according to the pore size in the range of 2-50 nm. In addition, the particles had crystallite size between 4.9 and 9.0 nm. The electrocatalytic activities of prepared HPW/AAB electrodes were studied in the oxidation of NO2- and the results revealed that the electrodes possessed relatively higher nitrite oxidation currents than AAB electrode. The best electroactivity was observed for HPW3/AAB electrode (AAB + + 20 wt % HPW) and the limit of detection (3 sigma) was determined as 8 mu M

Parcijalno hidrogenovanje jestivih ulja - sinteza i verifikacija katalizatora na bazi nikla

Developed in the late 1800s as a butter substitute, margarine is made with vegetable oils. Margarine was created by a scientist from Provence (France) Hippolyte Mege-Mouries, in response to an offer by the Emperor Louis Napoleon III. To formulate his entry, Mege-Mouries used margaric acid, a fatty acid component isolated in 1813 by Michael Chevreul and named because of the lustrous pearly drops that reminded him of the Greek word for pearl - margarites.Parcijalna hidrogenacija jestivih biljnih ulja je veoma važna operacija u industriji biljnih masti i ulja. Katalizator koji se uobičajeno upotrebljava u industrijskom procesu parcijalne hidrogenaciji biljnih ulja je nikl nanešen na silikatni nosač. Izbor i hemijska sinteza niklovog katalizatora, postupak nanošenja nikla i promotora na nosač i aktivacija katalizatora su od vitalnog značaja za dobijanje visoko-aktivnog hidrogenacionog katalizatora. Niklov katalizator, nanešen na domaći prirodni silikat (dijatomejska zemlja) sintetizovan je precipitacionom metodom sa NaaCOs. Aktivnost sintetizovanog katalizatora je testirana na pilot postrojenju (5 kg) i u industrijskom reaktoru kapaciteta 5 tona. Dobijena aktivnost sintetizovanog katalizatora potvrđena je i na "scale-up" nivou sa faktorom 1000