Improved analytical prediction of facilitation factors in facilitated transport

An improved analytical solution for the facilitation factor in facilitated transport that covers a wide range from diffusion-limited to reaction-limited mass transport has been developed. This solution is attained after assuming a small non-zero solute concentration at the membrane exit. Based on previous analysis a graph that provides a reasonable downstream solute concentration was extracted. The exit solute concentration was found to be dependent on both the mobility ratio, , and the inverse Damkohler number, ε. The quick and reasonable results in this work can be used for design and scale-up purposes.     

Kinetics of the gas-phase reaction between iodine and monogermane and the bond dissociation energy D(H3Ge?H)

The title reaction has been investigated in the temperature range of 403–446 K. Monoiodogermane and di-iodogermane together with hydrogen iodide were the main products, although at high conversions at least one other product was formed. GeH₃I is clearly the primary product. Initial rates were found to obey the rate law over a wide range of initial iodine and monogermane pressures. Secondary reactions (of GeH₃I with I₂) affect the subsequent kinetics, although at sufficiently high initial reactant ratios ([GeH₄]₀/[I₂]₀ ≥ 100) an integrated rate equation fits the data with the same rate constants as the initial rate expression. The observed kinetics are consistent with an iodine atom abstraction chain mechanism, and for the step log k₁ (dm³/mol·s) = (11.03 ± 0.13) – (52.3 ± 1.0 kJ/mol)/RT ln 10 has been deduced. From this the bond dissociation energy D(GeH₃? H) = 346 ± 10 kJ/mol (82.5 kcal/mol) is obtained. The significance of this value, together with derived values for Ge–Ge and Ge–C bond strengths, is discussed.     

High-energy collisions of intrinsically deformed particles

The Chou-Yang model of the elastic profile function for high-energy collisions is modified to take into account the possibility that the projectile, the target, or both, are deformed from sphericity. Simple expressions for the elastic amplitudes and total cross sections are derived under the assumption that the collision times are much shorter than the rotation periods of the projectile and target (adiabatic approximation). A simplified, purely geometric interpretation of the results on total cross sections is given and justified in terms of the quantum-mechanical treatment.     

Mechahism of the base promoted fragmentatiom of chloroacetylhydrazide

Experiments are described supporting the positions that the visible transient intermediate occurring during the fragmentation of chloroacetylhydrazide is the anion of acetyldiazene, and that the concurrent reduction is not a simple recombination reaction.     

On MTL's First Decade

Three experiments used multiple methods—open-ended assessments, multiple-choice questionnaires, and interviews—to investigate the hypothesis that the development of students' understanding of the concept of real variable in algebra may be influenced in fundamental ways by their initial concept of number, which seems to be organized around the notion of natural number. In the first two experiments 91 secondary school students (ranging in age from 12.5 to 14.5 years) were asked to indicate numbers that could or could not be used to substitute literal symbols in algebraic expressions. The results showed that there was a strong tendency on the part of the students to interpret literal symbols to stand for natural numbers and a related tendency to consider the phenomenal sign of the algebraic expressions as their “real” sign. Similar findings were obtained in a third, individual interview study, conducted with tenth grade students. The results were interpreted to support the interpretation that there is a systematic natural number bias on students' substitutions of literal symbols in algebra.