Use of the quartz crystal microbalance for kinetic studies of thermal decomposition of solids

A quartz crystal microbalance has been proposed for studies on the temperature dependence of the linear rate of a reaction interface advance in topochemical reactions of the thermal decomposition of solids. A quartz crystal microbalance has been used in investigations of the CuSO₄ · 5H₂O dehydration. The data agree fairly well with those available in the literature. Advantages and disadvantages of the method proposed are discussed.     

Effects of injector geometry and sample matrix on injection and sample loading in integrated capillary electrophoresis devices

The double-T injector design employed in many microchip capillary electrophoresis devices allows for the formation of very small (50-500 pL) sample plugs for subsequent analysis on-chip. In this study, we show that sample plugs formed at the channel junction can be geometrically defined. The channel width and injector symmetry prove to be of great importance to good performance. A unique pushback of solvent into the side channels can be induced when the side channels have a very low resistance to flow, and this helps to better define the injected sample plug. Samples and running buffers of differing ionic strength (e.g., 10 mM KCl buffer and 20 mM KCl sample) can yield widely variable results in terms of plug shape and amount injected (variations of 1.5 to 10x). Applying bias voltages to all the intersecting channels aids in controlling the plug shape. However, when the ionic strengths of buffer and sample are not matched, the actual amount injected (up to 10x variations) can be inconsistent with the appearance of the plug formed in the injector (up to only 30 % variations). Operating at constant pH and ionic strength produced the most consistent results. This report examines the effects of altering the injector geometry and solution ionic strengths, and presents the results of using bias voltages to control plug formation. The observed results should provide a benchmark for modeling of the fluid dynamics in channel intersections.     

Generalized Sidon sets of perfect powers

The Ramanujan Journal - For $$h \ge 2$$ and an infinite set of positive integers A, let $$R_{A,h}(n)$$ denote the number of representations of the positive integer n as the sum of h distinct terms...     

Weak decays of heavy mesons in the instantaneous Bethe Salpeter approach

In the framework of the instantaneous Bethe Salpeter equation we investigate weak decays ofB andD mesons. Mesons are described asq $\bar q$ states interacting via a mixture of a scalar and a vector confining kernel and a one gluon exchange. The model parameters are fixed by a fit to the meson mass spectrum including also the light mesons. We calculate form factors and compare our results to the pole dominance hypothesis. From a fit to ARGUS and CLEO data onB→D ^*?v semileptonic decay we extract the Cabbibo Kobayashi Maskawa matrix element to beV _cb =(0.032 ± 0.003)(1.49ps/τ _b )^1/2 The Isgur Wise function is calculated utilizing the heavy quark mass limit. Finally, we give some results on nonleptonic decays.     

Observation of isomeric states in197Bi

The high spin states of¹¹⁹Te, populated in¹¹⁰Pd(¹³C,4n) and¹¹⁰Pd(¹²C,3n) reactions, have been studied through -ray spectroscopy. The level scheme has been established upto a spin of 55/2. Three-quasiparticle states, based on g² _7/2h_11/2 and g_7/2d_5/2h_11/2 configurations, have been identified. The 35/2 and 39/2 states are suggested to be the fully aligned states constituted by five valence h_11/2 ³, g_7/2, d_5/2 quasiparticles.     

Investigation of the extraction equilibria in the system hexachloridorhenate(IV)-neotetrazolium chloride-dichloroethane-water

The neotetrazolium hexachloridorhenate(IV) (NTReCl(6)) has been synthesized and its composition checked. The optimum conditions for the extraction of NTReCl(6) with dichloroethane have been established. The recovery factor for one-fold extraction is R = 74%. The distribution constant, K(D), extraction constant, K(ex), and ion-association constant, beta, have been determined. Neotetrazolium chloride was found to be suitable reagent for extraction-spectrophotometric determination of rhenium(IV) ((NTReCl(6)) = 3.42 +/- 0.20 x 10(4)M(-1) cm(-1)).     

The effects of media properties on the horseradish peroxidase-catalyzed fluorogenic reaction

The effects of media properties including buffers, acidity, solvents and surfactant on horseradish peroxidase-catalyzed fluorogenic reaction were investigated. The results showed that the so-called non-fluorescent hydrogen donors were in fact fluorescent. There existed an acid—base equilibrium in the fluorescent dimer product. For p -hydroxyphenylpropionic acid, a pK_a value of 8.0 for the product was obtained from its titration curve. The product fluorescence increased with higher pH, however, a longer time was needed to reach the reaction equilibrium due to the pH mismatch problem. Cationic micelles cetyltrimethylammonium bromide and cetyltrimethylammonium chloride could reduce the pH mismatch and offered a way to further increase the determination sensitivity. Finally, a micelle-enhanced flow-injection analysis of horseradish peroxidase is suggested.     

Strong converse inequality for Kantorovich polynomials

For the Kantorovich polynomial approximationK _n (f, t), 1<p≤∞, we prove that, for somem, This equivalence includes a strong converse inequality of type B.     

The occupation time of Brownian motion in a ball

LetW be a Wiener process of dimensiond3, starting from 0, and letX(t) be the total time spent byW in the ball centered at 0 with radiust. We give an affirmative answer to a conjecture of Taylor and Tricot⁽¹⁶⁾ on the tail distribution ofX(t). Lévy's lower functions ofX(t) are characterized by an integral test.