Search results for "spin [neutron star]"

Effectiveness of Entrepreneurial Universities: Experiences and Challenges in Digital Era (A Systemic Approach)

2021

The modern world actively discusses the challenges that will lead to the Fourth Industrial Revolution. As the specialists assume, part of the jobs will be replaced by artificial intelligence. In addition, creation of completely new jobs is expected. As for the jobs that might be maintained in future, skills upgrading will be particularly important. In such a turbulent environment of economic development, universities, and in particular entrepreneurial universities, play a significant role. We think so as these universities have special structures that promote form a university-industry-government triple helix, reskilling and commercialization of new ideas, etc. Due to the above-mentioned fa…

Analysis of the spatial distribution of free radicals in ammonium tartrate by pulse EPR techniques

2009

Using pulse electron paramagnetic resonance (EPR) on a series of l(+)-ammonium tartrate (AT) dosimeters exposed to radiations with different linear energy transfer (LET), we assessed the ability of pulse EPR spectroscopy to discriminate the quality of various radiation beams such as (60)Co gamma-ray photons, protons and thermal neutrons at various doses by analyzing the local radical distributions produced by the different beams. We performed two types of pulse EPR investigations: two-pulse electron spin echo decay obtained by varying the microwave power, and a double electron-electron resonance (DEER) study. Both methods provide information about the dipolar interactions among the free rad…

Squaramide-based reagent for selective chromogenic sensing of Cu(II) through a zwitterion radical.

2010

A minimalist squaramide-based chemodosimeter for Cu(2+) is described. Upon selective chelation to 2, Cu(2+) induces the formation of a highly colored zwitterionic radical, which is kinetically stable for hours. The presence of a radical is confirmed by EPR and ESI-MS. It is then possible to use reagent 2 for visual and selective sensing of Cu(2+) at neutral pH.

Second-harmonic free-induction decay in a two-level spin system

1983

Growth of paramagnetic defects by gamma rays irradiation in oxygen-deficient silica

2005

Abstract We report an electron paramagnetic resonance (EPR) study of gamma rays irradiation effects on an oxygen-deficient silica obtained from fused quartz. We have found that three types of E′ centers, E α ′ , E γ ′ and E δ ′ , and a paramagnetic defect in a spin triplet state (S = 1) are induced. The EPR signals dependence on the microwave power have been investigated. The concentrations of these centers as a function of gamma ray irradiation show that for high dose a limit value is reached suggesting a generation process from precursors.

EPR investigations of polymeric and H2O2 -modified C3N4 -based photocatalysts

2019

The C3N4 -based nanopowders prepared by thermal condensation of melamine (MCN) with subsequent thermal etching (MCN-TE) and H2O2 -treatment were investigated by Q- and X-band EPR spectroscopy in dark and upon in situ UVA or visible-light exposure. Lorentzian signal at g = 2.003, more pronounced in the case of the thermally etched material, dominates EPR spectra of MCN and MCN-TE. More complex spectra were found for H2O2 -treated photocatalysts revealing the presence of signals attributed to the radicals produced via H2O2 interaction with C/N sites in the C3N4 polymeric network. The X-band spectra monitored upon in situ irradiation of the C3N4 -based photocatalysts evidenced the intensity gr…

Ultrasound-assisted MnO2 catalyzed homolysis of peracetic acid for phenol degradation: The assessment of process chemistry and kinetics

2013

Abstract The combination of peracetic acid (PAA) and heterogeneous catalyst (MnO 2 ) was used for the degradation of phenol in an aqueous solution in the presence of ultrasound irradiation (US). As a relevant source of free radicals (e.g. OH), peracetic acid was comprehensively studied by means of electron spin resonance (ESR) spin trapping (ST) techniques with the subsequent identification of free radicals by simulation based fitting (SBF) technique. The radical reaction mechanism, where hydroxyl radical was a primary product of O O bond rupture of PAA, was established taking into account radical reactions, occurring during sonolysis. The potential barriers and the reaction heat were deter…

Oxidation of small gas phase Pd clusters: A density functional study

2006

The adsorption sites of O2 on neutral PdN clusters (N = 1–4) were studied using spin density functional theory. Only for Pd1O2 molecular adsorption is found to be favorable. For Pd2–4O2 dissociative adsorption with the oxygen sitting on Pd bridge sites is preferred. Most Pd clusters remain in the same high spin states found for pure gas phase Pd clusters. Only the ground state of Pd4O2 increase its spin from a triplet to a quintet state. For molecular adsorption the O–O bond gets activated to a superoxo-like state.

Antiferromagnetism-Induced Spin Splitting in Systems Described by Magnetic Layer Groups

2021

Structure and physical properties of [mu-tris(1,4-bis(tetrazol-1-yl)butane-N4,N4 ')iron(II)] bis(hexafluorophosphate), a new Fe(II) spin-crossover co…

2004

[mu-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), [Fe(btzb)(3)](PF6)(2), crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T-1/2 = 174 K and a hysteresis of about 4 K between T-1/2 and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, Fe-57-Mossbauer spectroscopy, and variable temperature far and midrange FIR spectroscopy. The title compound crystallizes in the trigonal space group P (3) over bar (No. 147) with a unit cell content of one formula u…