End‐group composition of poly(3‐hexylthiophene)s prepared by in situ quenching of the grignard metathesis polymerization: Influence of additives and reaction conditions

The ability to prepare well‐defined semiconducting polymers is essential for understanding the link between structure and function in organic photovoltaic devices. A general, one‐pot method for altering the degree of functionality of end‐functionalized poly(3‐hexylthiophene)s (P3HT) prepared by Grignard metathesis (GRIM) polymerization has been developed. In the absence of additives, the degree of functionality of end‐functional P3HTs prepared by quenching of the GRIM polymerization with a Grignard reagent is dependent on the Grignard reagent utilized. In this study, additives such as styrene and 1‐pentene are shown to alter the end‐group composition of tolyl‐functionalized P3HTs as determined by Matrix‐assisted Laser Desorption Ionization Time‐of‐flight Mass Spectrometry. In particular, when quenching the GRIM polymerization with tolylmagnesium bromide, a modest decrease in the difunctional product is observed, and the yield of the monofunctional product increases significantly. Temperature and lithium chloride (LiCl) addition also play impactful roles. Monofunctional P3HT is found to be the major product (72% abundance) when the functionalization is done in the presence of LiCl and styrene at 0 °C, whereas in the absence of additives the monofunctional product is present at only 11% abundance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

On the possibility of using rubbers in Arctic conditions

This article is devoted to the specific features of the development of compositions and the use of frost-resistant rubbers. The main operating characteristics frost-resistant rubber and the specificity of their use in the Arctic climate are presented.     

On dimensionless parameters for generalization pressure head and flow rate characteristics of centrifugal disk pumps

Experimental study was performed for operation of a centrifugal disk pump at atmospheric air pressure. The dimensionless parameters were developed for generalization of experimental data on flow rate and head of the pump. The method for calculation of a pumping curve and throttling characteristic was offered through use of semiemperical generalization formulas. The method ensures a good accuracy in calculations, which is proved by comparison of calculation and experimental data for the pump tested.     

Synthesis and Crystal Structure of the Azide K4[Re6Sei8(N3)a6]·4H2O; Luminescence,Redox, and DFT Investigations of the [Re6Sei8(N3)a6]4– Cluster Unit

The reaction of K₄[Re₆Seⁱ₈(OH)^a₆] · 8H₂O with NaN₃ in water results in the formation of [Re₆Seⁱ₈(N₃)^a]^4– units that crystallize with K⁺ and H₂O to form K₄[Re₆Seⁱ₈(N₃)^a₆] · 4H₂O [P2₁/c (N°14), a = 9.0595(3) Å, b = 13.2457(4) Å, c = 13.2040(5) Å, β = 94.472(1)°]. In the solid state, the unit is characterized by N₃ linear groups forming bond angles of roughly 120° with the Re₆ cluster. The positions of the ν_as and ν_sy bands as well as N–N–N deformation modes of the N₃ groups are discussed. Luminescence properties of the [Re₆Seⁱ₈(N₃)^a]^4– unit were measured in the solid state and in an acetonitrile solution. The redox potential of the [Re₆Seⁱ₈(N₃)^a]^4–/[Re₆Seⁱ₈(N₃)^a]^3– system was measured in acetonitrile. Experimental results were analyzed in the light of density functional theory calculations.     

Acylstannanes: Cleavable and Highly Reactive Photoinitiators for Radical Photopolymerization at Wavelengths above 500 nm with Excellent Photobleaching Behavior

Within this work, a novel acylstannane‐based photoinitiator (PI) is presented. Tetrakis(2,4,6‐trimethylbenzoyl)stannane ( 1 ) displays outstanding properties compared to state‐of‐the‐art acylgermane‐based initiators. Most importantly, the initiator shows absorption up to 550 nm, which allows higher penetration depths, especially in highly filled photopolymers. Besides that, 1 shows extremely high photoinitiating activity towards (meth)acrylic double bonds, as well as very fast photobleaching. Furthermore, unlike many organotin compounds, 1 shows surprisingly low cytotoxicity.     

Search for the νμ → ντ oscillation with the OPERA hybrid detector

This work reviews the status of the international OPERA experiment aimed at searching for the ν_μ → ν_τ oscillation. Development of the emulsion techniques in the preceding DONUT and CHORUS experiments is described. A brief overview of the NOMAD experiment is given, in which properties of ν_τ interactions were thoroughly investigated. Characteristics of the CERN-Gran Sasso (CNGS) neutrino beam are given, the structure of the OPERA hybrid detector and the functions of its subsystems are considered, and the automatic emulsion scanning technique is briefly reviewed. Uncertainties in reconstruction of event parameters using the electronic and emulsion detectors are discussed and the procedure adopted in the experiment for identification of ν_τ interactions is described. The main sources of background in the search for ν_μ → ν_τ oscillation are considered. Topologies of the first two ν_τ candidates observed in the OPERA emulsion detector are presented. Possibilities of increasing the ν_τ interaction selection efficiency using multidimensional criteria are briefly discussed.