Charge separation in the excited state electron donor—acceptor compounds containing the piperazine moiety

Three bridged electron donor—acceptor systems are investigated containing a 4-cyano-1-ethenylnaphthalene electron-acceptor and piperidine (compound 1), phenylpiperazine (2) and 4-methoxyphenylpiperazine (3) electron-donating groups. In the intramolecular charge-transfer states of 1 and 2, the extent of charge separation is similar, but in compound 3 the positive charge is shifted towards the more powerful arylamine donor site, which results in a significantly greater dipole moment. Optical absorption spectra of model radical cations demonstrate that the predominant charge localization on the trialkyl nitrogen in 2 and on the aryl nitrogen in 3 are a consequence of the bistable nature of the piperazine donors.     

Proton-neutron final-state interaction in the reaction 2H(p,pp)n at 6.4, 10.0, 15.9, 19.85 and 25.8 MeV

This paper presents and analyzes the results of measurements of the proton-neutron final-state interaction (FSI) at 6.4, 10.0, 15.9, 19.85 and 25.8 MeV. At each energy nine angular combinations were measured and for each experiment the cross section was measured along the whole kinematic curve. The data are compared with the predictions of S-wave rank-one and rank-two separable potential models. The potentials used in one of the models reproduce the experimental S-wave N-N phase shifts. Fairly large differences between experiment and theory are found in the FSI regions and in the other regions of the kinematic curves. These disagreements cannot be attributed to off-shell effects. The inclusion of the tensor force and the P-wave N-N interaction in the calculations reduces the disagreements considerably at the higher energies. However, systematic differences of 10% to 20% remain.     

Secondary ion mass spectrometry of compositional changes in garnet films

Secondary ion mass spectrometry (SIMS) has been used as the analytical method to obtain directly depth concentration profiles of Pb (Ca and Ga) in magnetic garnet films. The films had the general composition (Y,Pb)₃(Fe,Si,Ga)₅O₁₂ and were grown onto substrates of Ca-doped Y₃Fe₅O₁₂ by means of the LPE technique. The film-substrate interface was found to be reasonably sharp. For dipping without rotation, a transient layer of about 0.28 μm thickness, in which the Pb content changed appreciably, was found arising from the initial non-steady state growth regime. In the case of dipping with rotation, this transient layer was of the order of 0.05 μm and displayed much smaller changes in the Pb content. Changes were also found at the surface of the film due to withdrawal of the specimen from the melt.     

Intramolecular switching between dipolar resonance structures in singlet and triplet excited states detected by TRMC

Transient changes in the real and imaginary component of the complex permittivity of a flash-photolyzed solution can be monitored with nanosecond time resolution using the time-resolved microwave conductivity (TRMC) technique. Effects caused by rapid (picosecond), flip—flop switching between dipolar resonance structures in the S₁ and T₁ states of molecules with mirror symmetry have been observed.     

Direct Dynamic Protein-Affinity Selection Mass-Spectrometry

Mobile phase chromatographic conditions for the selective separation of metoprolol from related amino alcohols have been evaluated using Hypercarb as support and carbon dioxide with addition of methanol as mobile phase. The objective for the presented study was to show the unique ability of the porous graphitized carbon surface to separate closely structurally related substances. Experimental results, using Hypercarb and “chromatographic normal phase conditions” (SFC), are presented with focus on how to control retention and to improve peak performance. A high concentration of basic aliphatic amine additive was required in order to elute the amine analytes as symmetrical peaks. N,N-Dimethyloctylamine was preferred over triethylamine since the retention was markedly shorter though the selectivity and resolution were virtually the same. The selectivity can be optimized by altering the temperature of the column. A high selectivity was demonstrated between metoprolol and two homologues with one and two extra methylene groups inserted between the secondary nitrogen atom and the carbon atom with a hydroxyl group attached. The mobile phase flow rate effect the column efficiency only to a minor extent as the steepness of the van Deemter curve for metoprolol was virtually flat in the range studied: 0.5–3.0 mL min^?1.     

Analysis of meeting protocols by formalisation, simulation, and verification

Organizations depend on regular meetings to carry out their everyday tasks. When carried out successfully, meetings offer a common medium for participants to exchange ideas and make decisions. However, many meetings suffer from unfocused discussions or irrelevant dialogues. To study meetings in detail, we first formalize general properties of meetings and a generic meeting protocol to specify how roles in a meeting should interact to realize these properties. This generic protocol is used as a starting point to study real-life meetings. Next, an example meeting is simulated using the generic meeting protocol. The general properties are formally verified in the simulation trace. Next, these properties are also verified formally against empirical data of a real meeting in the same context. A comparison of the two traces reveals that a real meeting is more robust since when exceptions happen and the rules of the protocol are violated, these exceptions are handled effectively. Given this observation, a more refined protocol is specified that includes exception-handling strategies. Based on this refined protocol a meeting is simulated that closely resembles the real meeting. This protocol is then validated against another set of data from another real meeting. By iteratively adding exception handling rules, the protocol is enhanced to handle a variety of situations successfully.     

Sparse classification with paired covariates

Advances in Data Analysis and Classification - This paper introduces the paired lasso: a generalisation of the lasso for paired covariate settings. Our aim is to predict a single response from two...