Absolute detector calibration using twin beams

A method for the determination of absolute quantum detection efficiency is suggested based on the measurement of photocount statistics of twin beams. The measured histograms of joint signal-idler photocount statistics allow us to eliminate an additional noise superimposed on an ideal calibration field composed of only photon pairs. This makes the method superior above other approaches presently used. Twin beams are described using a paired variant of quantum superposition of signal and noise.     

Solution and Solid‐State Studies on the Halide Binding Affinity of Perfluorophenyl‐Armed Uranyl–Salophen Receptors Enhanced by Anion–π Interactions

The enhancement of the binding between halide anions and a Lewis acidic uranyl–salophen receptor has been achieved by the introduction of pendant electron‐deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion–π interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding.     

The effect of plasma treatment on structure and properties of poly(1-butene) surface

This paper is focused on the chemical and morphology changes in the surface of poly(1-butene) (PB-1) generated by plasma treatment. The radio frequency capacitively coupled plasma (air, argon, argon then allylamine, argon containing ammonia and argon with octafluorocyclobutane) was used. Modified surface of PB-1 was characterized by contact angle measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. The surface hydrophilization by air and argon with ammonia plasmas was evaluated as most sufficient. Oppositely, a high level of hydrophobicity of PB-1 surface was reached by combination of argon with octafluorocyclobutane plasma. Upon plasma modification, hydrophilicity/hydrophobicity of treated surfaces remained stable within three days under air atmosphere and then values of contact angle slowly recovered to those of unmodified PB-1. However, morphology and surface chemical composition of plasma-modified samples remained generally unchanged during observed time. Changes in surface hydrophilicity/hydrophobicity of plasma-treated PB-1 were attributed to variance of conformation of the surface molecules.     

Improvement of the Ca determination accuracy with k 0-INAA using an HPGe coaxial detector with extended energy range efficiency calibration

Journal of Radioanalytical and Nuclear Chemistry - We show that use of the radionuclide 56Co for calibration of the full energy peak efficiency, ε, of a coaxial HPGe detector, in addition to...     

On Nested Bethe Ansatz for RTT Algebra of o(2n) Type

We study the highest weight representations of the RTT algebras for the R matrix of o(2n) type by the nested algebraic Bethe ansatz. We show how auxiliary RTT algebra à can be used to find Bethe vectors and Bethe conditions. For special representations, in which representation of RTT algebra à is trivial, the problem was solved by Reshetikhin.

     

Simple Synthesis of Fluorinated Graphene: Thermal Exfoliation of Fluorographite

Fluorinated graphene can be prepared directly by thermal exfoliation of fluorographite. The exfoliation was performed in a dynamic nitrogen atmosphere at various temperatures and the exfoliation products were analysed in detail by GC‐MS. The structure and properties of all prepared fluorinated graphenes with various contents of fluorine were characterized by a number of analytical techniques. The results show both the dependence of fluorine concentration on exfoliation temperature and the suitability of this method for the synthesis of graphene with controlled concentration of fluorine. The high‐temperature exfoliated fluorographite exhibits a high heterogeneous electron transfer rate and excellent catalytic properties towards the oxygen reduction reaction. These synthetic procedures can open a simple way for the synthesis of fluorinated graphene‐based devices with tailored properties.     

Discovering implied constraints in precedence graphs with alternatives

During automated problem solving it may happen that some knowledge that is known at the user level is lost in the formal model. As this knowledge might be important for efficient problem solving, it seems useful to re-discover it in order to improve the efficiency of the solving procedure. This paper compares three methods for discovering certain implied constraints in the constraint models describing manufacturing (and other) processes with serial, parallel, and alternative operations. In particular, we focus on identifying equivalent nodes in the precedence graph with parallel and alternative branches. Equivalent nodes correspond to operations that either must be all simultaneously present or none of them can be present in the schedule. Such information is frequently known at the user level, but it is lost in the formal model. The paper shows that identifying equivalent nodes is an NP-hard problem in general, but it is tractable if the graph has a nested structure. As the nested structure is typical for real-life processes and workflows, we use the nested graphs to experimentally compare the proposed methods.     

Ultra-Long Lived Luminescent Triplet Excited States in Cyclic (Alkyl)(amino)carbene Complexes of Zn(II) Halides

The high element abundance and d¹⁰ electron configuration make Zn^II-based compounds attractive candidates for the development of novel photoactive molecules. Although a large library of purely fluorescent compounds exists, emission involving triplet excited states is a rare phenomenon for zinc complexes. We have investigated the photophysical and -chemical properties of a series of dimeric and monomeric Zn^II halide complexes bearing a cyclic (alkyl)(amino)carbene (cAAC) as chromophore unit. Specifically, [(cAAC)XZn(μ-X)₂ZnX(cAAC)] (X=Cl ( 1 ), Br ( 2 ), I ( 3 )) and [ZnX₂(cAAC)(NCMe)] (X=Br ( 4 ), I ( 5 )) were isolated and fully characterized, showing intense visible light photoluminescence under UV irradiation at 297 K and fast photo-induced transformation. At 77 K, the compounds exhibit improved stability allowing to record ultra-long lifetimes in the millisecond regime. DFT/MRCI calculations confirm that the emission stems from ³XCT/LE_cAAC states and indicate the phototransformation to be related to asymmetric distortion of the complexes by cAAC ligand rotation. This study enhances our understanding of the excited state properties for future development and application of new classes of Zn^II phosphorescent complexes.     

Monotone retractability and retractional skeletons

We prove that a countably compact space is monotonically retractable if and only if it has a full retractional skeleton. In particular, a compact space is monotonically retractable if and only if it is Corson. This gives an answer to a question of R. Rojas-Hernández and V.V. Tkachuk. Further, we apply this result to characterize retractional skeleton using a topology on the space of continuous functions, answering thus a question of the first author and a related question of W. Kubi?.