Autogenic synthesis of green- and red-emitting single-phase Pr(2)O(2)CO(3) and PrO(1.833) luminescent nanopowders

This Article reveals a rare synthesis of pure Pr(2)O(2)CO(3) (POC) nanopowder by thermolysis (700 °C) of a single chemical precursor in an autogenic reaction. The autogenic thermolysis of praseodymium acetate is a solvent-free, efficient, and straightforward approach yielding luminescent POC nanoparticles. The as-prepared POC nanopowder converted to PrO(1.833) (PO) powder via combustion. Methodical morphological, structural, and compositional characterizations of POC and PO powders are carried out, supported by mechanistic elucidation and the photoluminescent properties.     

Spectroelectrochemical Study of 9‐Substituted Acridines with Potential Antitumor Activity

The electrochemical and spectroelectrochemical behavior of 9‐substituted with ? CN and ? COOH acridine N‐oxides with potential antitumor activity was investigated. In SER spectra of the investigated compounds, the ring stretching vibration at 1568 cm^?1 for 9‐CN‐substituted compound respectively 1639 cm^?1 for 9‐COOH‐substituted compound was analyzed. Cyclic voltammograms indicates that the reduction potential ?0.766 V for ? CN substituted compound increase towards ?0.745 V for ? COOH substituted compound. The proposed theoretical method in the electrochemical impedance spectroscopy uses a reference redox dielectrode and a multielectrode containing the compound. To account for the change of electrochemical impedance we have considered two theoretical quantities: a pseudocapacitance and a pseudo inductance. Two possible arrangements of them: in series, respective in parallel can be used like criteria of drug classification.     

Foldamers of bifunctional diketopiperazines displaying a β-bend ribbon structure

The synthesis of two oligomers, of a bifunctional diketopiperazine scaffold DKP-1, formally derived from the cyclization of l-aspartic acid and (S)-2,3-diaminopropionic acid, is reported. A trimeric and a tetrameric structure were prepared by solution-phase peptide synthesis (Boc strategy). Conformational analysis of these derivatives was carried out by a combination of ¹H NMR spectroscopy, CD spectroscopy, and molecular modeling, and revealed the formation of β-bend ribbon involving 10-membered H-bonded rings and a reverse turn of the growing peptide chain.     

Chlorella minutissima—A Promising Fuel Alga for Cultivation in Municipal Wastewaters

It is imperative to slash the cost of algal oil to less than $50 bbl^?1 for successful algal biofuel production. Use of municipal wastewater for algal cultivation could obviate the need for freshwater and the nutrients—N and P. It would also add CO₂ through bacterial activity. Chlorella minutissima Fott et Nova dominated the entire phycoflora year around and through each stage of the wastewater treatment at the oxidation pond system of Wazirabad (Delhi) in India. The ability to grow so profusely in such varied and contrasting situations made this alga unique. Besides pollution tolerance, it grew heterotrophically in dark under acidic conditions and as a mixotroph in presence of light over a range of organic C substrates. It could utilize both ammoniacal and nitrate nitrogen, survived anaerobicity, 5% NaCl and ?10 bar of osmotic stress. C. minutissima grew at pH 4–11 and raised the pH set initially by 1 to 3 units in 7.5 h. It showed gigantism and largely kept afloat in presence of utilizable organic carbon, while flocculated in mineral medium and on aging. The alga also possessed potential for biofuel production. The studied parameters indicate why C. minutissima was a potential biomass builder in municipal sewage and could be used to determine which other alga(e) may serve the purpose.     

A liquid chromatography–atmospheric pressure photoionization tandem mass spectrometric method for the determination of azaarenes in atmospheric particulate matter

The development, optimization and validation of a liquid chromatography–atmospheric pressure photoionization tandem mass spectrometric (LC–APPI/MS/MS) method for the determination of 15 azaarenes (4-azafluorene, benzo[h] and -[f]quinoline, phenanthridine, acridine, 1-azafluoranthene, 4-azapyrene, benz[a]- and -[c]acridine, -10-azabenzo[a]pyrene, 7,9- and 7,10-dimethylbenz[c]acridine, dibenz[a,j]-, -[c,h] and [a,i]acridine) in airborne particulate matter is described. Each compound was detected and quantified operating in multiple reaction monitoring mode. Extraction of azaarenes was achieved using accelerated solvent extraction (ASE) with dichlormethane/methanol (50/50, v/v). After extraction, no additional clean-up procedure like solid phase or liquid/liquid extraction was necessary. Limits of quantification (S/N × 10) ranged from 0.2 pg/μl to 1.4 pg/μl, matrix dependent recoveries were between 57% and 94%, with relative standard deviations from 8% to 17%. Applicability of the method was demonstrated analyzing 10 samples of particulate matter (PM_2.5) collected in winter 2008. In all samples dimethylbenz[c]acridines as well as dibenzacridines were below the limit of quantification, concentration of the remaining analytes were in the range from 0.002 ng/m³ to 0.356 ng/m³.     

Thermal expansion of supported and freestanding graphene: lattice constant versus interatomic distance

By using ab initio molecular dynamics calculations, we show that even where the graphene lattice constant contracts, as previously reported for freestanding graphene below room temperature, the average carbon-carbon distance increases with temperature, in both free and supported graphene. This results in a larger corrugation at higher temperature, which can affect the interaction between graphene and the supporting substrate. For a weakly interacting system as graphene/Ir(111), we confirm the results using an experimental approach which gives direct access to interatomic distances.     

FIXED POINT RESULTS ON METRIC-TYPE SPACES

In this paper we obtain fixed point and common fixed point theorems for self- mappings defined on a metric-type space, an ordered metric-type space or a normal cone metric space. Moreover, some examples and an application to integral equations are given to illustrate the usability of the obtained results.     

On a New Class of Systems of Generalized Quasi-Variational Inequalities

We introduce new types of systems of generalized quasi-variational inequalities and we prove the existence of the solutions by using results of pair equilibrium existence for free abstract economies. We consider the fuzzy models and we also introduce the random free abstract economy and the random equilibrium pair. The existence of the solutions for the systems of quasi-variational inequalities comes as consequences of the existence of equilibrium pairs for the considered free abstract economies.     

Deformations of permutation representations of Coxeter groups

The permutation representation afforded by a Coxeter group W acting on the cosets of a standard parabolic subgroup inherits many nice properties from W such as a shellable Bruhat order and a flat deformation over ?[q] to a representation of the corresponding Hecke algebra. In this paper we define a larger class of “quasiparabolic” subgroups (more generally, quasiparabolic W-sets), and show that they also inherit these properties. Our motivating example is the action of the symmetric group on fixed-point-free involutions by conjugation.