Structure of styrene–butadiene–styrene block copolymers by diffusion analysis

In this study, solvent sorption was used to investigate the morphology of a styrene–butadiene–styrene (SBS) triblock copolymer. The sorption process was found to deviate from the normal Fickian character, usually found in conventional elastomer–solvent systems, because of the presence of an interfacial region for both polybutadiene and polystyrene. This interphase absorbed solvent at a temperature below its glass transition and contributed to the resulting non-Fickian time-dependent diffusion process. The equilibrium diffusion coefficient was estimated to be 3.2 × 10^?7 cm²/sec regardless of the casting surface. Nevertheless, according to the sorption measurements, the casting surface did have an effect on the approach to equilibrium. The results indicated a denser packing of the molecules and hence a decreased diffusion coefficient for Teflon and glass cast films, because of internal stresses left within the films during casting.     

Intensities of rotational lines in first overtone bands for axially symmetric molecules of the group C3v

The interaction of vibration and rotation is considered in the computation of the intensities of rotational lines in the first overtone bands of axially symmetric molecules of the group C_3v. The calculation utilizes the contact transformation method through first order of approximation as outlines by Hanson and Nielsen. General formulas for the intensities of the lines in the first overtone bands 2ν_n and 2ν_m are obtained, where n and m denote normal modes of species A₁ and E, respectively. It is found that to this order of approximation the usual selection rules ΔJ = 0, ±1 and ΔK = 0 are observed for the parallel overtone band 2ν_n. For the overtone band 2ν_m, the selection rules are more complicated, being ΔJ = 0, ±1; Δl_m = 0 and ΔK = 0, Δl_m = ±2 and $\text{Δ}\text{K = ?1}$, or Δl_m = ±2 and ΔK = ±2.     

A new efficient and practical synthesis of 2-deoxy-l-ribose

An efficient and practical route for large-scale synthesis of 2-deoxy-l-ribose starting from l-ascorbic acid was developed in eight steps without chromatographic purification for all intermediates. Additionally, (2S,3R)-3,4-epoxy-1,2-O-isopropylidenebutane-1,2-diol, a versatile intermediate in carbohydrate synthesis, was also prepared readily in excellent yield as a key intermediate.     

Zur konstruktion bewerteter dicksonscher fastkörper

Zusammenfassung  After a short introduction to the valuation theory of nearfields, we give criteria for when a valuation of a skewfield F is also a valuation of the Dickson nearfield F^K which is derived from F by the coupling K on F. For the construction of examples, a rational function field F =K(t) is given. The set of all prolongations of a valuation v on K to F is well known. Sufficient conditions are given which guarantee that couplings K on F and elements are in this sense compatible so that w is a valuation of the Dickson nearfield F^K. Examples demonstrate the results.

     

Static and cyclic behaviours of multistorey infilled frames with different interface conditions

Results are presented from a study aimed at a deeper understanding of the static and cyclic behaviours of non-integral, partially integral and integral infilled frames. In the first part of the study the load-deflection behaviour, stress distribution and collapse modes under static loads are examined and in the second part the hysteretic characteristics, energy dissipation capacities and degradation properties under cyclic loads are evaluated.     

ESR studies on the preparation of the sulphite radical anion,SO3−., in aqueous solution

The sulphite radical anion, SO₃^?., was generated from the redox reactions between the bisulphite ion, HSO₃^?, and transition-metal i     

Design and fabrication of automated sedimentation-based separation and siphon-based extraction for detection of allergic reaction on a centrifugal microfluidic disc

We report the design and fabrication of a novel and fully integrated polymer-based centrifugal microfluidic disc for rapid automatic allergens detection. All essential steps for a single test including flow valving, sequencing, mixing, separation, extraction, and sedimentation for final detection are automatically conducted within 30 min on a centrifugal microfluidic disc. Our design features a siphon-based valving and analyte extraction structure where the released analyte is separated and subsequently extracted by a siphon valve into the detection chamber. Incorporating the siphon valve and a series of capillary valves, we realize automated detection of allergic reaction on a centrifugal microfluidic disc.