ESI-MS spectra of 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones

Twelve 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones were investigated by tandem mass spectrometry using positive as well as negative electrospray ionization. The influence of the electron affinity of the substituent and the steric effect on the fragmentation is discussed. Pyridinones with a substituent of low proton affinity show loss of water, HCN or benzene from the pyridinone ring in the first step of MS2 fragmentations. Oppositely, if a substituent with high proton affinity is present on the phenyl ring in the 4-position of pyridinone, the fragmentation paths are complex, depending mainly on the substituent proton acceptor ability. Elimination of neutral molecules CO, HCN, H2O, PhH (benzene) or Ph and CN radicals are fragmentation processes common for all compounds in the subsequent steps of the fragmentations

The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide) were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax) of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax), p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed

BEAMDB and MOLD—Databases at the Serbian Virtual Observatory for Collisional and Radiative Processes

In this contribution we present a progress report on two atomic and molecular databases, BEAMDB and MolD, which are web services at the Serbian virtual observatory (SerVO) and nodes within the Virtual Atomic and Molecular Data Center (VAMDC). The Belgrade Electron/Atom (Molecule) DataBase (BEAMDB) provides collisional data for electron interactions with atoms and molecules. The Photodissociation (MolD) database contains photo-dissociation cross sections for individual rovibrational states of diatomic molecular ions and rate coefficients for the chemi-ionisation/recombination processes. We also present a progress report on the major upgrade of these databases and plans for the future. As an example of how the data from the BEAMDB may be used, a review of electron scattering from methane is described

Rosetta mission: Electron scattering cross sections-data needs and coverage in BEAMDB database

The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is handicapped by a lack of detailed knowledge of electron impact cross sections which highlights the need for a broad range of electron scattering data from the molecular systems detected on the comet. In this paper, we present an overview of the needs for electron scattering data relevant for the understanding of observations in coma, the tenuous atmosphere and on the surface of 67P/Churyumov-Gerasimenko during the Rosetta mission. The relevant observations for elucidating the role of electrons come from optical spectra, particle analysis using the ion and electron sensors and mass spectrometry measurements. To model these processes electron impact data should be collated and reviewed in an electron scattering database and an example is given in the BEAMD, which is a part of a larger consortium of Virtual Atomic and Molecular Data Centre-VAMDC

Analiza znanja i stavova studenata zdravstvenih studija o upotrebi stimulativnih supstanci u sportu

Background/Aim. Since the beginning of competitive sports, athletes have been trying to improve their abilities by taking various substances. The problem of using prohibited substances is not strictly tied to elite athletes; it is also present in the general population. The aim of this study was to test the knowledge and attitudes of the students regarding the use of stimulative substances and dietary supplements in sports. Methods. A cross-sectional study was performed among students at the College of Health and Professional Studies in Belgrade, Serbia. The data was collected by filling in an especially designed questionnaire. Results. Knowledge of prohibited substances and methods was characterized as 'good' with 24.2% of respondents, namely 8.09% of males and 16.1% of females; knowledge of the adverse effects of prohibited substances and methods on health was demonstrated by 17.7% (9.03% of male respondents and 8.72% of female respondents). Conclusion. Student population is not knowledgeable enough about the problems of prohibited substances use and their negative effects on one's health. The comparative analysis of our and European researches on knowledge, attitudes and uses of prohibited substances show a rather uniform prevalence rate. Not being aware of the adverse effects shows the need to further educate students.Uvod/Cilj. Sportisti oduvek u takmičarskom sportu pokušavaju da poprave svoje sposobnosti uzimanjem različitih supstanci. Problem korišćenja nedozvoljenih supstanci nije vezan isključivo za elitne sportiste, već je prisutan i u opštoj populaciji. Cilj rada bio je ispitivanje znanja i stavova studenata u vezi sa upotrebom stimulativnih supstanci i dijetetskih suplemenata u sportu. Metode. Istraživanje je srovedeno kao studija preseka kod studentske populacije u Visokoj zdravstvenoj školi strukovnih studija u Beogradu. Podaci su prikupljani popunjavanjem posebno dizajniranog upitnika. Rezultati. Dobro znanje o nedozvoljenim supstancama i metodama, pokazalo je 24,2% ispitanika (8,09% muškog pola i 16,1% ženskog pola), a o neželjenim efektima zabranjenih supstanci i metoda na zdravlje, znanje je pokazalo 17,7% ispitanika (9,03% muškog pola i 8,72% ženskog pola). Zaključak. Populacija studenata nema dovoljno znanja o problemu upotrebe nedozvoljenih supstanci i njihovim negativnim posledicama po zdravlje. Komparativna analiza našeg i evropskih istraživanja znanja, stavova i upotrebe nedozvoljenih supstanci ukazuje na približno ujednačene stope prevalencije. Nepoznavanje neželjenih efekata ukazuje na potrebu za dodatnom edukacijom studenata

Study of electron transmission through a metallic capillary

In this work we study the transmission of charged particles through a single cylindrically shaped metallic capillary of microscopic dimensions with a large aspect ratio. We used electrons as projectiles. Our results suggest the existence of guiding of the electron beam by a metallic capillary.29th International Conference on Photonic, Electronic, and Atomic Collisions (ICPEAC), Jul 22-28, 2015, Toledo, Spai

Orange-Reddish Light Emitting Phosphor GdVO 4 :Sm 3+ Prepared by Solution Combustion Synthesis

The gadolinium vanadate doped with samarium (GdVO 4 :Sm 3+ ) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve the full crystallinity, the material was annealed in air atmosphere at 900°C. Phase identification in the postannealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscopy (SEM). Photoluminescence characterization of the emission spectrum and time-resolved analysis have been performed using the tunable laser optical parametric oscillator excitation and the streak camera. Several strong emission bands in the Sm 3+ emission spectrum were observed, located at 567 nm ( 4 G 5/2 – 6 H 5/2 ), 604 nm ( 4 G 5/2 – 6 H 7/2 ), and 646 (654) nm ( 4 G 5/2 – 6 H 9/2 ), respectively. The weak emission bands at 533 nm ( 4 F 3/2 – 6 H 5/2 ) and 706 nm ( 4 G 5/2 – 6 H 11/2 ) and a weak broad luminescence emission band of VO 4 3− were also observed by the detection system. We analyzed the possibility of using the host luminescence for two-color temperature sensing. The proposed method is improved by introducing the temporal dependence in the line intensity ratio measurements

Uticaj rastvarača i strukture na reaktivnost 6-supstituisanih nikotinskih kiselina sa diazodifenilmetanom u aprotičnim rastvaračima

The rate constants for the reactions of diazodiphenylmethane (DDM) with 6-substituted nicotinic acids in aprotic solvents at 30°C were determined. The obtained second order rate constants in aprotic solvents, together with literature data for benzoic and nicotinic acids in protic solvents, were used for the calculation of solvent effects, employing the Kamlet-Taft solvatochromic equation (linear solvation energy relationship - LSER) in the form: log k = log k0 + + sΠ*+ aα + bβ. The correlations of the kinetic data were performed by means of multiple linear regression analysis taking appropriate solvent parameters. The sign of the equation coefficients (s, a and b) were in agreement with the postulated reaction mechanism, and the mode of the solvent influences on the reaction rate is discussed based on the correlation results. A similar contribution of the non-specific solvent effect and electrophilic solvation was observed for all acids, while the highest contribution of nucleophilic solvation was influenced by their high acidity. Correlation analysis of the rate data with substituent óp parameters in an appropriate solvent using the Hammett equation was also performed. The substituent effect on the acid reactivity was higher in aprotic solvents of higher dipolarity/polarizability. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute-solvent interaction on the acid reactivity.Konstante brzina 6-supstituisanih nikotinskih kiselina sa diazodifenilmetanom (DDM) su određene u različitim protičnim i aprotičnim rastvaračima na 30°C. Izračunate konstante brzina, kao i literaturni podaci, korišćeni su za izračunavanje efekata rastvarača korišćenjem Kamlet-Taft-ove solvatohromne jednačine. Konstante brzina su korelisane sa parametrima rastvarača korišćenjem Kamlet-Taft-ove jednačine oblika: log k = log k0 + + sΠ*+ aα + bβ. Korelacije dobijenih kinetičkih rezultata sa odgovarajućim parametrima rastvarača su izvedene primenom metode višestruke linearne regresione analize. Znak koeficijenata (s, a i b) u dobijenim korelacijama je u saglasnosti sa reakcionim mehanizmom. Sličan doprinos nespecifičnih efekata i elektrofilne solvatacije rastvarača je uočen za sve ispitivane kiseline, a najveći doprinos nukleofilne solvatacije polaznog stanja je posledica visoke kiselosti ispitivanih kiselina. Uticaj rastvarača na vrednosti reakcionih konstanti je diskutovan na osnovu dobijenih korelacionih rezultata. Korelaciona analiza konstanti brzina sa óp konstantama supstituenata, u ispitivanom rastvaraču, izvršena je primenom Hammett-ove jednačine. Efekti supstituenata na reaktivnost ispitivanih kiselina su značajniji u aprotičnim rastvaračima visoke dipolarnosti/polarizabilnosti. Način prenosa efekata supstituenata je diskutovan u svetlu doprinosa interakcija rastvorak-rastvarač na reaktivnost ispitivanih kiselina

Kinetika reakcije 5-supstituisanih orotinskih kiselina sa dizaodifenilmetanom

Rate konstants for the reaction of eight 5-substituted orotic acids with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 ºC by the known spectrophotometricmethod. The determined rate constants were correlated with the equations: logk2 = ασ1+βσR+h logk2 = ασ1+βσR+ψν+h to detect the presence and investigate the influence of both electrical and steric substituent effects. The obtained results show that the electrical effect (the localized – field and delocalized – resonance) is predominant and that the steric effect, althought present, is releatively small in this reaction.Konstante brzine za reakciju osam 5-spstituisanih orotinskih kiselina sa diazodifenilmetanom (DDM) određene su na 30 ºC u dimetilformamidu (DMF) kao rastvarač u, poznatom spektrofotometrijskim metodom. Konstante brzina ispitivanih reakcija korelisane su sledećim jednačinama: logk2 = ασ1+βσR+h logk2 = ασ1+βσR+ψν+h sa ciljem da se odrede efekti supstituenata. Dobijeni rezultati ukazuju na to da su električni efekti supstituenata (induktivni i rezonantni) preovlađujući, a da su sterni efekti supstituenata, iako su prisutni, u odnosu na njih relativno mali

The Auger spectra in argon induced by electron impact – new measurements with high resolution

The Auger spectrum of argon in the kinetic energy region (135–235 eV) has been measured using a non-monochromatic electron beam (incident energy from 313 to 2019 eV) at two ejection angles of 60° and 90° with a high resolution electrostatic analyzer. The electron impact energies of 313 and 323 eV have been used in order to disentangle the contribution of the ionization and decay of the 2s state. The systematic analysis of the measured spectra shows the dominance of the Coster-Kronig transitions from the 2s ionization in the energy region 135–159 eV and 208–235 eV, while the Auger transitions from the 2p ionization are dominant in the energy region 160–208 eV. The high resolution of the present work led to the observation of a certain number of new features in two energy regions 135–159 and 208–235 eV, respectively. Recent literature data on the cascade Auger processes and threshold formation of Ar2+ satellite states allow the assignment of some of them, while other have been left without assignments. The influence of the PCI effect on the line-shape, width and energy position of the features in the kinetic energy region 200–208 eV has been also investigated and the PCI shift versus excess energy above threshold compared with previous data and theoretical predictions