Narrow band quantitative and multivariate electroencephalogram analysis of peri-adolescent period

ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages.     

Generation and Reactivity of a One-Electron-Oxidized Manganese(V) Imido Complex with a Tetraamido Macrocyclic Ligand

The synthesis and X-ray structure of a new manganese(V) mesitylimido complex with a tetraamido macrocyclic ligand (TAML), [Mn^V(TAML)(N-Mes)]⁻ ( 1 ), are reported. Compound 1 is oxidized by [(p-BrC₆H₄)₃N ]^+.[SbCl₆]⁻ and the resulting Mn^VI species readily undergoes H-atom transfer and nitrene transfer reactions.     

Systematic Investigation of Silver–Carbon Bonding in Coordination Frameworks with Aryl Ligands That Contain Ethynyl and Ethenyl Substituents

Single‐crystal X‐ray diffraction of a series of ten crystalline silver(I)–trifluoroacetate complexes that contained designed ligands, each of which was composed of an aromatic system that was functionalized with terminal and internal ethynyl groups and a vinyl substituent, provided detailed information on the influence of ligand disposition and orientation, coordination preferences, and the co‐existence of different types of silver(I)–carbon bonding interactions (silver–ethynide, silver–ethynyl, silver–ethenyl, and silver–aromatic) on the construction of coordination networks that were consolidated by argentophilic and weak inter/intramolecular interactions. The complex Ag L10? 6 AgCF₃CO₂ ? H₂O ? MeOH ( HL10 =1‐{[4‐(prop‐2‐ynyloxy)‐3‐vinylphenyl]ethynyl}naphthalene) is the first reported example that exhibits all four kinds of silver(I)–carbon bonding interactions in the solid state.     

Natural Products with Anti‐Bredt and Bridgehead Double Bonds

Well over a hundred years ago, Professor Julius Bredt embarked on a career pursuing and critiquing bridged bicyclic systems that contained ring strain induced by the presence of a bridgehead olefin. These endeavors founded what we now know as Bredt’s rule (Bredtsche Regel). Physical, theoretical, and synthetic organic chemists have intensely studied this premise, pushing the boundaries of such systems to arrive at a better understood physical phenomenon. Mother nature has also seen fit to construct molecules containing bridgehead double bonds that encompass Bredt’s rule. For the first time, this topic is reviewed in a natural product context.     

On the formation mechanism for electrically generated exciplexes in a carbazole–pyridine copolymer

Although carbazole‐containing copolymers are frequently used as hole‐transporting host materials for polymer organic light‐emitting diodes (OLEDs), they often suffer from the formation of undesired exciplexes when the OLED is operated. The reason why exciplexes sometimes form for electrical excitation, yet not for optical excitation is not well understood. Here, we use luminescence measurements and quantum chemical calculations to investigate the mechanism of such exciplex formation for electrical excitation (electroplex formation) in a carbazole–pyridine copolymer. Our results suggest that the exciplex is formed via a positively charged interchain precursor complex. This complex is stabilized by interactions that involve the nitrogen lone pairs on both chain segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

2,4,6-Tris(4-nitrophenoxy)-1,3,5-triazine: a hexagonal host framework stabilised by the NO2-trimer supramolecular synthon

The title molecule forms a honeycomb network of molecular and nitro-trimer synthons with guest species included in the hexagonal voids.     

Particle Creation in Cosmological Models with Varying Gravitational and Cosmological “Constants”

Einstein's field equations with variablegravitational coupling G = G(t) and decaying vacuumenergy density = (t) are considered asdescribing matter creation in a cosmological framework.The particle creation rate is determined by thevariation rate of both G and . By consideringsimple phenomenological evolution laws for G and Lambda,an exact solution of the gravitational field equationsfor a flat Friedmann-Robertson-Walker (FRW)space-time is obtained leading to a self-consistentcosmological model describing matter and entropygeneration in the very early Universe.     

Picosecond optoelectronic switching in CdS0.5Se0.5

So far only few materials have been investigated for their application in fast opto-electronic switching. These materials are Si, GaAs and InP. The difficulty in obtaining a high resistivity specimen of group IV elemental semiconductors puts constraints on their high power handling capability. Most of the group III–V compounds have the possibility of showing up of Gunn effect at high fields, which has undesirable effect in high voltage switching. We have, therefore, investigated a mixed II–VI compound CdS_0.5Se_0.5 for its potential use as an opto-electronic switch.     

A model for the plane to plane variations in catalytic activity seen during nitric oxide decomposition on platinum

Previous work has shown that the reactivity of platinum for nitric oxide decomposition varies significantly with the geometry of the exposed surface of the platinum. Here, the available data are compared to the predictions of a model, which is based on conservation of orbital symmetry and a simplified picture of the band structure of the surface. The model predicts that the (100) face of platinum should be more active than either the (111) or the (110). The (410) should be more active still. These predictions agree with recent experiment. The model makes several other predictions which need to be tested experimentally. These results suggest that symmetry conservation methods, similar to the ones developed by Woodward and Hoffmann for organic reactions, could yield many valuable insights into the relative activity of various catalyst structures.