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A new algorithm for computation of the initial velocity of enzyme reaction at the time zero is proposed. This algorithm makes it possible to reduce the systematic error of measurements to the minimum, to estimate the reaction velocity in test samples regardless of the enzyme activity levels, and to minimize the assay time. The study is illustrated by an example of salivary alpha-amylase and standard reagent kit. The algorithm should not be applied if conjugated enzyme systems are used because there is a long initial lag phase in the kinetic curve.

Al/Ni multilayer bridge films, which were composed of alternate Al and Ni layers with bilayer thicknesses of 50, 100 and 200 nm, were prepared by RF magnetron sputtering. In each bilayer, the thickness ratio of Al to Ni was maintained at 3:2 to obtain an overall 1:1 atomic composition. The total thickness of Al/Ni multilayer films was 2 μm. XRD measurements show that the compound of AlNi is the final product of the exothermic reactions. DSC curves show that the values of heat release in Al/Ni multilayer films with bilayer thicknesses of 50, 100 and 200 nm are 389.43, 396.69 and 409.92 J g−1, respectively. The temperatures of Al/Ni multilayer films were obviously higher than those of Al bridge film and Ni bridge film. Al/Ni multilayer films with modulation of 50 nm had the highest electrical explosion temperature of 7000 K. The exothermic reaction in Al/Ni multilayer films leads to a more intense electric explosion. Al/Ni multilayer bridge films with modulation period of 50 nm explode more rapidly and intensely than other bridge films because decreasing the bilayer thickness results in an increased reaction velocity.

The general equation for liquid film resistance to gas absorption in scrubbers, derived by us in a previous paper 1), was applied to experiments of Cryder and Maloney2), treating the absorption of carbon dioxide in diethanolamine solutions. Our equation proved to be valid also in this case, when it is assumed that the reaction is a pseudo-third order reaction. In reality it will be a succession of two second order reactions, as no temperature influence on the reaction velocity constant is found.

As a contribution to the study of the formation of humic acids in soil, a polarographic investigation has been made of the oxidation of some poly-hydroxybenzenes in aqueous solution under different conditions. The formation of hydroxyquinone as an intermediate in the oxidation of hydroquinone was confirmed. Indications were obtained for the identity of some other intermediate reaction products. The important conclusion is drawn that the presence of tyrosinase or certain clay-minerals frequently not only influences the reaction velocity, as is sometimes supposed, but also may alter the course of the oxidation reaction.

The addition of ozone to 3-methylpyridine, 2,6-dimethylpyridine, and 2,4,6-trimethylpyridine was studied quantitatively. After hydrolysis of the reaction products, the quantity of ammonia formed was measured. The results show that in all the cases investigated the action of ozone leads to the formation of a diozonide; no indication of the addition of ozone to the CN bond was found with any of these compounds. Further the velocity was measured of the ozone addition to the abovementioned compounds, and also to pyridine, 2- and 4-methylpyridine, and 4-ethylpyridine. The reaction velocity is smaller than that of the corresponding benzene derivatives. Introduction of methyl groups into the pyridine nucleus enhances the reactivity with regard to ozone.

From the reaction mixtures obtained by brominating and nitrating 2-hydroxypyridine-N-oxide the sole disubstituted products isolated were the 3,5-derivatives. The course of the bromination and nitration of 2-hydroxypyridine-N-oxide differs from the analogous reactions of 2-hydroxypyridine only in an increased reaction velocity.

In this paper experiments are described in which tin and lead are used as selective catalysts for the synthesis of methyltrichlorosilane (80-90% yield) and methyldichlorosilane (72% yield), respectively. For the methyltrichlorosilane synthesis, the reaction velocity is given as a function of temperature and conversion of methyl chloride at atmospheric pressure.

The reaction velocity of the hydrolysis of sodium monochloroacetate was determined in concentrated solutions and alkaline medium at 40° and 50°. It was found that the reaction follows the bimolecular equation. However, the reaction constant increases considerably with the normality of the hydroxide, which was explained by an effect of the total electrolyte concentration. The temperature coefficient of the reaction was calculated to be 3.0 per 10°.

Methylene diphenyl dicarbamate (MDC) was synthesized from methyl phenyl carbamate (MPC) and trioxane using sulfuric acid (H2SO4) as catalyst. The effects of reaction temperature, reaction time, molar ratio of reactants and the content of catalyst have been studied in details. The results showed that H2SO4 exhibited high catalytic activity with the merits of moderate reaction velocity. Under the conditions of n(MPC)/n(trioxane) = 3:1, reaction temperature of 95°C, reaction time of 3.5 h and 30% H2SO4, the conversion of MPC reached 99.0% with the selectivity of MDC 81.6%. Moreover, the H2SO4 catalyst was reused five times without obviously activity decrease. Based on the identification of byproducts, a possible reaction mechanism was proposed.

The changes of n-pentane asphaltene content, penetration, softening point, and ductility of two Saudi Arabian paving asphalts have been studied during aging. Further, aging kinetics of asphalt, based on the change of n-pentane asphaltene content, has been studied. Some correlative kinetic parameters were calculated and the aging kinetics equation of asphalt was gained. The value calculated depending on the equation was in accordance with the experimental data. And the relationship between the composition of the high grade paving asphalt and its aging resistant performances was revealed. It showed that the aging of high grade paving asphalt was a first-order reaction. AH-70 paving asphalt has the following characteristics: higher reaction active energy, less reaction velocity constant, lower aging velocity, and better aging resistance performance compared with AH-90 paving asphalt. The changes of penetration, softening point, and ductility of asphalt during aging further proved that the kinetic mo...

Noninvasive visualization and investigation of interactions among proteins, biomolecules, and enzymes in living cells is an important goal for biologists, and fluorescence probes are powerful tools for this purpose. Because many target molecules are present in only trace amounts, high sensitivity is very important, and it is common to improve the sensitivity of fluorescence probes by focusing on high reaction velocity, K(d). (Gee, K. R.; Archer, E. A.; Lapham, L. A.; Leonard, M. E.; Zhou, Z.; Bingham, J.; Diwu, Z. Bioorg. Med. Chem. Lett. 2000, 10, 1515-1518.) So far, we have designed and synthesized various highly sensitive fluorescence probes based on the above concepts. (Gabe, Y.; Urano, Y.; Kikuchi, K.; Kojima, H.; Nagano, T. J. Am. Chem. Soc. 2004, 126, 3357-3367. Komatsu, K.; Urano, Y.; Kojima, H.; Nagano, T. J. Am. Chem. Soc. 2007, 129, 13447-13454.) Nevertheless, they were sometimes insufficiently sensitive to detect biomolecules in living cells, despite high chemical sensitivity in cuvette. In this report, we suggest a new approach to increase the sensitivity of fluorescence probes, focusing on their intracellular retention. Since calcein is well-retained, we investigated its structural, chemical, and optical characteristics and found that the iminodiacetic acid group (IAG) is a key structure for the intracellular retention. We next designed and synthesized novel fluorescence probes containing IAGs. They showed superior intracellular retention, making it possible to visualize low concentrations of target molecules that would be difficult to observe with conventional probes and permitting long-term observation in living cells. Improvement of intracellular retention of fluorescence probes holds great promise as a strategy for developing a wide range of highly sensitive probes for studies on various biological phenomena.

International audience; The activity and stability of peroxidase in aqueous solutions of two ionic liquids (ILs) have been studied. The ILs selected were 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate, [emim][MDEGSO 4 ], and 1-ethyl-3-methylimidazolium ethylsulfate, [emim][EtSO 4 ]. Experiments were performed at room temperature using concentrations of ILs between 5 and 50% (v/v) and pH values in the range from 5 to 9. The initial activity of the enzyme in these ILs at optimized conditions (pH 7 and 5-10% IL) was similar or higher than that achieved with buffer solution. Kinetic studies showed that maximum reaction velocity (V max) decreased with increasing concentration of IL. The effect of [emim][EtSO 4 ] concentration on the decrease of V max was higher than that of [emim][MDEGSO 4 ]. It was found that [emim][EtSO 4 ] was a more potent inhibitor on peroxidase activity. The peroxidase studied was active in the ILs investigated, and the enzyme exhibited a higher stability in ILs at the optimized conditions. Kinetic studies showed that inhibition was a noncompetitive type in both ILs.

The methylene-blue-sensitized photooxidation of sulphite by molecular oxygen is catalysed by trace metals. In the absolute absence of catalysing metal ions the reaction would not proceed at all. With increasing concentrations of Mn(II) and Fe(III) the reaction velocity and consequently the overall quantum yields increase.

(1) From the experimental study of the nitrogenation of calcium carbide the author concluded its mechanism to be as follows: (a) adsorptions of nitrogen on the carbide, (b) formation of intermediate compound Ca(CN)2 temporarily, (c) breaking of Ca(CN)2 into CaCN2 and C. (2) Equations for this (gas-solid) reaction velocity were derived from above view. For constant temperature and pressure (Remark: Graphics omitted.) and for changing pressure (Remark: Graphics omitted.) (3) The coincidence of these equations with the experimental results were discussed. (4) The heat of activation for the reaction of the adsorbed nitrogen and carbide to form calcium cyanide was calculated to be approximately 86 Cal./mol.

(1) An interpretation on the real meaning of the observed oxidation velocity of ferrous hydroxide under the conditions of the author’s experiments was given to prevent misunderstanding of the author’s papers. (2) The reason, why the experimental conditions, under which the author’s measurements were carried out, were adopted, was described. (3) It was discussed that the oxidation velocity of ferrous hydroxide, observed by A. Krause under quite different conditions, will have quite a different meaning as that, observed by the author. The difference of the real meaning of the observed reaction velocity, caused by the difference of the experimental conditions, will explain why the effect of temperature, which was negligible under the author’s conditions, was found by A. Krause to be very great.

Neutral and alkaline solutions in water of the nitrophenyl phosphates are very stable in the dark. These compounds, however, and the meta derivative in particular were found to undergo a remarkable rapid hydrolysis when exposed to visible or ultra-violet light. The reaction velocity is independent of the hydrogen ion concentration at pH's between 3 and 12 but increases strongly at higher pH's. Nitrophenol and phosphoric acid could be traced as the products of this photochemical reaction. The reaction proved to be zero order; the rate did not change upon varying of the temperature from 25° to 40° C. The nitrophenyl sulphates show an analogous behaviour but for the fact that the increase of reaction rate at higher pH's does not occur and that the difference in the rate of photochemical reaction between the meta compound on the one hand and the ortho and para derivatives on the other hand are even greater than with the phosphates. The experimental evidence points to a purely photochemical (non sensitized) reaction, the nature of which is tentatively discussed.

The rate of reaction of iron and hydrogen sulfide has been studied in an oxygen-free system in the presence of sodium chloride brine, in the presence and absence of an oil phase under a constant mixing rate at 40 G and 80 C. The experimental data are plotted according to a previously derived equation for the iron-acetic acid system, and are shown to be in agreement with that equation. Values of K, the overall reaction velocity, are obtained from the slopes. From the K values for three sets of experiments at 40 C and 80 C, values for the temperature coefficient are calculated, and are shown to correspond to the range of values expected for diffusional control. The presence of an oil phase seems to have little influence on the reaction rate. Another group of measurements on the iron-hydrogen sulfide system was carried out in the presence of corrosion inhibitors. While all the data of the inhibited reactions will show reasonable straight line plots, when plotted according to the diffusional equation, such plots have little meaning with the good inhibitors, because there is no essential change with time in the loss-in-weight values when they are used at 50 ppm. There seems to be some possibility that good inhibitors function by forming a particularly efficient non-permeable adsorbed film with iron sulfide corrosion products. 6.2.2

Estimation of the volume of hydrogen consumed by a static method with Cu-Cr-O under atmospheric pressure of hydrogen at 180°C by hydrogenation of whale oil was-studied kinetically. It was observed that the reaction is zero order to the concentration of the molecule to be hydrogenized, and, in spite of it, the reaction velocity gradually decreases due to the reversible poisoning of catalyst. An assumption was made that a poisonous substance is formed in the process of catalysis, and that its amount is proportional to the degree of hydrogenation. The following formula is presented. dx/dt=K_1(N_o-K_2x)

If ethylene–vinyl acetate copolymers are converted with aluminum alcoholates, crosslinked products will form. This reaction was studied on the basis of the viscosity variation and the amount of acetic acid ester formed. The constants of the reaction velocity for the conversion with various aluminum alcoholates were determined and a reaction mechanism is discussed.

In continuation of a previous paper [1], this paper discusses the absorption of oxygen in sodium sulphite solutions with varying reaction velocity constants (Section 3) and the absorption of carbon dioxide in water (Section 4), both in one column with a 1-in. Raschig ring packing. From the experiments with chemical absorption the surface renewal rate of the liquid, s, was determined. From this and from the measurements of the interfacial area, a, [1], a.√sD-values were obtained. These values are compared with the kLO-values obtained from the experiments on physical absorption. For relatively low gas and liquid flow rates the a.√s D-values agree very well with the kLO-values, but above the loading point the values obtained with chemical absorption are larger than those obtained with physical absorption. A tenative explanation for this difference is given.

It has been experimentally determined that the velocity of reaction between nitrogen and calcium carbide at high temperatures is not directly proportional to the nitrogen-pressure, but there exists the following relation: (Remark: Graphics omitted.) \oindentwhere P denotes the pressure, K and α certain constants depending upon temperature and other conditions of the reaction.It has also been found that the higher the temperature the greater is the effect of pressure-increase to the velocity of reaction, though the effect of the pressure-increase becomes smaller at higher pressures. At lower pressures the velocity of the reaction is nearly proportional to the pressure.

1. Assumed as monomolecular reaction, the velocity of the decom-position of potassium monochloracetate in aqueous solutions is measured, K_25°=0.837×10^-6 and K_30°=3.21×10^-62. The velocities of the following reactions are measured, CH2CLCOOK+KOH = CH2OHCOOK+KCL K_20°=0.227×10^-4, K_25°=0.521×10^-4 and K_30°=1.23×10^-4 CH2CLCOONa+NaOH=CH2OHCOONa+NaCl K_25°=0.381×10^-4, K_30°=0.704×10^-4 and K_35°=2.18×10^-4The velocity constant of potassium salt is larger than that of sodium salt. 3. The reaction velocity of potassium monochloracetate with potassium hydroxide is retarded by the presence of another salt (i.e. KNO3).

(1) A method for calculating both reaction velocity and activation energy in the case when the reaction has been carried out in the thermal separation column of Clusius and Dickel has been described. (2) The method has been applied to the polymerisation reaction of acetylene previously investigated by the present authors. (3) It has been found that the calculated heat of activation is slightly smaller than our preliminary value, but larger than the directly observed value by Taylor and van Hook, and that the calculated velocity constants are several times larger than those hitherto have been observed.

Die Nickelcarbonylbildung lauft an Gitterbereichen mit erhohter Fehlordnung, z. B. an Korngrenzen oder mechanisch deformierten Stellen, beschleunigt ab. Unter Einwirkung von CO lassen sich durch Gasatzung Kristallorientierungen und Korngrenzen sichtbar machen. Mit Hilfe kinetischer und thermodynamischer Messungen wird die uberschussige freie Enthalpie tribomechanisch beanspruchter Gitterbereiche bestimmt und der Einflus des Aktivitatszustandes des verformten Festkorpers auf die Geschwindigkeit der Nickelcarbonylbildung untersucht. Wahrend des Beanspruchungsvorganges treten energetisch instabile Zustande auf, deren Aktivitat die der eingefrorenen irreversiblen Gitterstorungen nach Unterbrechung der Bearbeitung noch ubertrifft. Auf die technische Bedeutung dieser Prozesse wird hingewiesen. The formation of Ni(CO)4 takes place at distorted sites of the Ni-lattice (grain boundaries or mechanically deformed areas) with enhanced velocity. Orientations of crystals and grain boundaries become visible after etching with CO. The excess free enthalpy of the mechanically deformed lattice areas has been determined by kinetic and thermodynamic measurements. The influence of the activity of the deformed solid on the reaction velocity has been investigated. There are energetically instable states during the process of deformation. The activity of these states exceeds that of the lattice distortions after interruption of the mechanical working. A reference is given on the technical application.

The temperature dependence of the rates of three reactions in solution which the Arrhenius equation fails to express has been analyzed in terms of equations involving higher powers of the temperature and an improved fit of the experimental results obtained. The significance of the equations in terms of the thermodynamic parameters of the activation process is discussed.

1. The photochemical reversible reaction of the alkaline solution of malachite green was studied with the quartz-mercury-lamp, and its nature was discussed. 2. The reaction velocities were determined both in the light and the dark reaction, using Nutting’s spectro-photometer. The former is proportional to the intensity of light and the latter to the concentration of the alkali added. 3. The temperature coefficient of the reaction velocity of the light reaction was found to be unity at the interval between 25° and 35°C. 4. Equation of the reaction of first order was derived with approximation for the light reaction.

熱擴散管を反應管として使用し,高温部を形成する電熱線をして熱的,接解的又はその兩作用を生ぜしむればある種の化學反應に於て,その遂行に好都合な點のある事は既報せし所である.併し反應管内の温度が均一ならざるがため,壓の減少より簡單に速度恒數及び活性化熱等を算出できぬ難點がある.依て本報にては之等を求むる一般方式を導いた.次にこれな著者等がさきに測定せるアセチレンの重合反應に適用したるに,妥當と思はるる速度恒數と活性化熱とを得た.

1. The oxidation velocity of stannous hydroxide suspended in sodium carbonate solution of various concentrations by means of air was studied. The oxidation velocity was independent of the quantity of stannous hydroxide. 2. The effect of the concentration of sodium carbonate on the reaction velocity was small. 3. It was ascertained that sodium stannite is oxidized rapidly, while stannous hydroxide is oxidized very slowly by means of air. 4. The effect of temperature on the reaction was small.

1. The homogeneous destructive hydrogenation of toluene was investigated at high hydrogen pressures, 2. A chain mechanisms is advanced for the investigated process on the basis of which an equation for the reaction velocity is derived which is consistent with the experimental results.

(1) The oxidation velocity of sodium sulphite solution was observed when air is passed at various velocities. (2) It was found that the oxidation velocities are independent of the concentration of sodium sulphite and the velocity constant was expressed as a linear function of the velocity of air passed. (3) The dissolution velocity of oxygen into water when the concentration of oxygen in the surface layer is kept zero, was calculated from the obserbed reaction velocity, and it was found to be expressed as a linear function of the velocity of air passed. (4) An interpretation of the mechanism of this reaction under the observed conditions was given. (5) The maximum value of the ratio of the total number of molecules of oxygen which enter into water to the total number of molecules of oxygen which collide with the unit boundary surface per unit of time at 25°C. was calculated from the observed results.

1. We have synthesized and characterized epoxyethylphenyldi(trimethylsiloxy)silane, epoxyethyltri(trimethylsiloxy)silane, and methylepoxyethyldi(trimethylsiloxy)silane. 2. Epoxidation of vinylorganosiloxanes by perbenzoic acid is a second-order reaction; the reaction velocity depends on the polarities and volumes of the substituent radicals at the silicon atom.

Twenty-three derivatives of N-alkyl-N-2-chloroethyl-N-ω-chloroalkylamine were prepared. It was proved that these compounds are completely monofunctional biological alkylating agents from the estimation of reaction velocity in vitro, but neverthless they exhibit a strong antitumor effect on rats bearing Yoshida sarcoma. The fact is very interesting from the point of the mode of action of nitrogen mustards.