Comparison of two types of vertically aligned ZnO NRs for highly efficient polymer solar cells

Vertically aligned ZnO nanorods (NR) are prepared by two different syntheses methods and applied on polymer solar cells (PSCs). The ZnO electrodes work as the electron transport layer with the P3HT:PCBM blend acting as the active material. Several organic blend solution conditions are optimized: concentration, solvent, and deposition speed. The effect of different NR electrode morphologies is analyzed on the solar cell performance and characterized by current–voltage curves and IPCE analyses. The photovoltaic performance of the solar cells was observed to be influenced by many factors, among them infiltration of the organic P3HT:PCBM blend within the ZnO NR layer. The infiltration of the active layer was monitored by cross section SEM and energy dispersive X-ray spectroscopy analyses. Our results show that higher power conversion efficiencies are achieved when shorter NRs lengths are applied. The best power conversion efficiency obtained was 2.0% for a 400 nm ZnO NR electrode. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Probability distribution analysis of single-molecule fluorescence anisotropy and resonance energy transfer

Analysis of anisotropy in single-molecule fluorescence experiments using the probability distribution analysis (PDA) method is presented. The theory of anisotropy-PDA is an extension of the PDA theory recently developed for the analysis of F?rster resonance energy transfer (FRET) signals [Antonik, M.; et al. J. Phys. Chem. B 2006, 110, 6970]. The PDA method predicts the shape of anisotropy histograms for any given expected ensemble anisotropy, signal intensity distribution, and background. Further improvements of the PDA theory allow one to work with very low photon numbers, i.e., starting from the level of background signal. Analysis of experimental and simulated data shows that PDA has the major advantage to unambiguously distinguish between shot noise broadening and broadening caused by heterogeneities in the sample. Fitting of experimental histograms yields anisotropy values of individual species, which can be directly compared with those measured in ensemble experiments. Excellent agreement between the ensemble data and the results of PDA demonstrates a good absolute accuracy of the PDA method. The precision in determination of mean values depends mainly on the total number of photons, whereas the ability of PDA to detect the presence of heterogeneities strongly depends on the time window length. In its present form PDA can be also applied to computed fluorescence parameters such as FRET efficiency and scatter-corrected fluorescence anisotropy. Extension of the PDA theory to low photon numbers makes it possible to apply PDA to dynamic systems, for which high time resolution is required. In this way PDA is developed as a sensitive tool to detect biomolecular heterogeneities in space and time.     

Disjunctivity and Alternativity in Projection Logics

We study the notions of disjunctivity and alternativity of orthomodular posets inthe context of orthoprojections or skew projections in C ^*-algebras.     

BROMOC-D: Brownian Dynamics/Monte-Carlo Program Suite to Study Ion and DNA Permeation in Nanopores

A theoretical framework is presented to model ion and DNA translocation across a nanopore confinement under an applied electric field. A combined Grand Canonical Monte Carlo Brownian Dynamics (GCMC/BD) algorithm offers a general approach to study ion permeation through wide molecular pores with a direct account of ion-ion and ion-DNA correlations. This work extends previously developed theory by incorporating the recently developed coarse-grain polymer model of DNA by de Pablo and colleagues [Knotts, T. A.; Rathore, N.; Schwartz, D. C.; de Pablo, J. J. J. Chem. Phys. 2007, 126] with explicit ions for simulations of polymer dynamics. Atomistic MD simulations were used to guide model developments. The power of the developed scheme is illustrated with studies of single-stranded DNA (ss-DNA) oligomer translocation in two model cases: a cylindrical pore with a varying radius and a well-studied experimental system, the staphylococcal α-hemolysin channel. The developed model shows good agreement with experimental data for model studies of two homopolymers: ss-poly(dA)(n) and ss-poly(dC)(n). The developed protocol allows for direct evaluation of different factors (charge distribution and pore shape and size) controlling DNA translocation in a variety of nanopores.     

Dimroth rearrangement in the row of new pyrano[3,4-c][1,2,4]triazolo[4,3-a][1,5-a]pyridines and synthesis of new heterocyclic systems: Pyranopyrazolo[4,3-e][1,2,4]triazolopyridines

New and effective methods for the synthesis of derivatives of pyrano[3,4-c][1,2,4]triazolo[4,3-a][1,5-a]pyridines were developed. Synthesized new tetracyclic heterocyclic systems containing pyrano[3,4-c]pyridine ring unknown in the literature were obtained for the first time. The rearrangement of Dimroth in the triazolo[4,3-a]pyridine systems for the first time was studied. The possibility of rearrangement of Dimroth in the new heterocyclic system has been investigated.     

Palladium-catalysed synthesis of allyl acetates from allenes

Allyl acetates were synthesised from allenes utilising methodology based on the general reactivity of π-allyl palladium intermediates which participate efficiently in transformations involving nucleophiles. Reactions of allenes and aryl iodides in the presence of AcONa and Pd(OAc)₂/PPh₃ as the catalytic system afforded allyl acetates in moderate to good yields. Monosubstituted allenes, depending on their structure, produced either a separable mixture of two regioisomeric products or a single regioisomer. As allylic acetates can be easily hydrolysed, the methodology is applicable for the synthesis of allyl alcohols as well.     

Rotational excitation cross sections of para-H2 + para-H2 collisions. A full-dimensional wave-packet propagation study using an exact form of the kinetic energy

A full-dimensional quantum dynamical study of the rotational excitation in para-para H2 + H2 collisions using the potential-energy surface of Boothroyd et al. [J. Chem. Phys. 116, 666 (2002)] is reported. The multiconfiguration time-dependent Hartree algorithm is utilized to propagate wave packets and the cross sections for collision energies up to 1.2 eV are determined by a flux analysis through the interaction of the wave packet with a complex absorbing potential. Calculations for a collection of total angular momenta up to J = 70 are performed; the missing channels are obtained with a J-interpolation algorithm.     

Quantum dissipative chaos in the statistics of excitation numbers

A quantum manifestation of chaotic classical dynamics is found in the framework of oscillatory number statistics for the model of a nonlinear dissipative oscillator. It is shown that the probability distributions and variances of oscillatory number states are strongly transformed in the order-to-chaos transition. A nonclassical, sub-Poissonian statistics of oscillatory excitation numbers is established for chaotic dissipative dynamics in the framework of the Fano factor and Wigner functions. It is proposed to use these results in experimental studies of the quantum dissipative chaos.     

Annulations of isoquinoline and β-carboline ring systems: synthesis of 8-oxoprotoberberine derivatives

Annulation processes of isoquinoline and β-carboline compounds have been investigated leading to synthetic routes for the preparation of 8-oxoprotoberberine derivatives. The key steps combined a diene formation/Diels-Alder cycloaddition reaction to afford the targeted polycyclic skeletons. Further oxidative transformations of the cycloadducts produced the 8-oxoprotoberberine type products. The alkaloids of this class are important natural products with a wide range of biological activity and the synthethic methodology described in this paper could prove to be useful for the preparation of the D-ring functionalised derivatives.