The oscillatory Landolt reaction. Empirical rate law model and detailed mechanism

Gáspár, Vilmos; Showalter, Kenneth

doi:10.1021/ja00250a019

Cited by 59 publications

(47 citation statements)

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“…The pH oscillator in this case is a variant of the Landolt reaction. 66 The alternating oxidation of sulfite and thiosulfate by iodate is accompanied by a periodic production or consumption of protons. This oscillation reaction varies the pH value between 5 and 7 periodically and then leads to DNA conformational switches.…”

Section: Evolution Of Kinetics By Changing Environmentmentioning

confidence: 99%

DNA nanomachines and their functional evolution

2009

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Since the establishment of the Watson-Crick model more than five decades ago, the understandings of DNA structures are well sufficient to enable applications of DNA in designing and assembling two-dimensional (2D) and three-dimensional (3D) structures at the nanoscale. Furthermore, the conformational switchability of DNA also enables the fabrication of nanoscale molecular machines, which can perform movements upon stimuli. In this article, we will summarize the present efforts on constructions of DNA nanomachines based on different driven mechanisms, and further discuss their evolutional processes, in order to find applications and future development directions.

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Section: Evolution Of Kinetics By Changing Environmentmentioning

confidence: 99%

DNA nanomachines and their functional evolution

2009

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“…Beside the reduction of iodate by iodide, we have also considered its reduction by sulfite. Gaspar and Showalter (1987) have adopted the simple rate law r(IO with k = 0.30 M −1 s −1 . This value was corrected later to k = 0.42 M −1 s −1 (Luo and Epstein, 1989b).…”

Section: Model Descriptionmentioning

confidence: 99%

Modelling iodide – iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

2007

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Abstract. The speciation of iodine in atmospheric aerosol is currently poorly understood. Models predict negligible iodide concentrations but accumulation of iodate in aerosol, both of which is not confirmed by recent measurements. We present an updated aqueous phase iodine chemistry scheme for use in atmospheric chemistry models and discuss sensitivity studies with the marine boundary layer model MIS-TRA. These studies show that iodate can be reduced in acidic aerosol by inorganic reactions, i.e., iodate does not necessarily accumulate in particles. Furthermore, the transformation of particulate iodide to volatile iodine species likely has been overestimated in previous model studies due to negligence of collision-induced upper limits for the reaction rates. However, inorganic reaction cycles still do not seem to be sufficient to reproduce the observed range of iodide -iodate speciation in atmospheric aerosol. Therefore, we also investigate the effects of the recently suggested reaction of HOI with dissolved organic matter to produce iodide. If this reaction is fast enough to compete with the inorganic mechanism, it would not only directly lead to enhanced iodide concentrations but, indirectly via speed-up of the inorganic iodate reduction cycles, also to a decrease in iodate concentrations. Hence, according to our model studies, organic iodine chemistry, combined with inorganic reaction cycles, is able to reproduce observations. The presented chemistry cycles are highly dependent on pH and thus offer an explanation for the large observed variability of the iodide -iodate speciation in atmospheric aerosol.

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“…17 The possible mechanism of the UA interaction with non-oscillating DR matrix was tested on a kinetic scheme that was suggested by Agreda et al, 44 and which expressed the kinetic complexity of the Dushman reaction. 45,46 The uric acid (C 5 H 4 N 4 O 3 ) can be oxidized with HIO 3 and I 2 47,48 under acidic condition through a mechanism in which the most characteristic products are alloxan (C 4 O 4 N 2 H 2 ) and urea (CON 2 H 4 ). On the other hand, based on the recorded strong potentiometric response to small amounts of UA injection in DR, it was suggested the UA oxidation occurs through interaction with hypoiodous acid, as a crucial step in which the most characteristic products are alloxan and urea.…”

Section: Interaction Of Ua With Both Bl Matrix and Dr Matrixmentioning

confidence: 99%

Kinetic analytical method for determination of uric acid in human urine using analyte pulse perturbation technique

Pejić

Anić

Cupić

et al. 2012

J. Braz. Chem. Soc.

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Novos métodos simples e confiáveis para a determinação de ácido úrico (UA) são propostos e validados. Para a determinação quantitativa de UA, duas matrizes foram usadas: a reação oscilatória de Bray-Liebhafsky (BL) em um estado estacionário de não equilíbrio, estável, próximo ao ponto de bifurcação (método A), e o subsistema não oscilante (mistura de KIO 3 e H 2 SO 4), isto é, reação de Dushman (RD) em um estado estacionário (método B). Os métodos propostos são otimizados num reator tanque continuamente agitado (CSTR) e aplicados com excelentes resultados na determinação de UA em amostras de urina humana. A relação linear entre o deslocamento potencial máximo DE m e o logaritmo da concentração de UA (processo A), ou entre DE m e a concentração UA (processo B) é obtido no intervalo de concentração 2,98 × 10-5-2,68 × 10-4 mol L-1 e 2,98 × 10-5-3,58 × 10-4 mol L-1 , respectivamente. Os métodos têm uma velocidade de processamento de amostra excelente de 30 amostras h-1 (método A) e 7 amostras h-1 (método B) com sensibilidade determinada para ser 1,1 × 10-5 mol L-1 (método A) e 8,9 × 10-6 mol L-1 (método B), e precisão RSD ≤ 3.4% para ambos os métodos. Alguns aspectos do possível mecanismo de ação de UA nos sistemas de reação oscilante BL e não-oscilante de Duschman, são discutidos em detalhe. Simple and reliable novel methods for the determination of uric acid (UA) are proposed and validated. For quantitative determination of UA, two matrices were used: the Bray-Liebhafsky (BL) oscillatory reaction in a stable non-equilibrium stationary state close to the bifurcation point (method A) as well as, the BL non-oscillating subsystem (mixture KIO 3 and H 2 SO 4), i.e., Dushman reaction (DR) in a steady state (method B). The proposed methods are optimized in a continuously fed well stirred tank reactor (CSTR) and applied with excellent results in the determination of UA in human urine samples. The linear relationship between maximal potential shift DE m , and both the logarithm of the UA concentration (procedure A) and UA concentration (procedure B) is obtained in the concentration range 2.98 × 10-5-2.68 × 10-4 mol L-1 and 2.98 × 10-5-3.58 × 10-4 mol L-1 , respectively. The methods have an excellent sample throughput of 30 samples h-1 (method A) and 7 samples h-1 (method B) with the sensitivity determined to be 1.1 × 10-5 mol L-1 (method A) and 8.9 × 10-6 mol L-1 (method B) as well as the precision RSD ≤ 3.4% for both methods. Some aspects of the possible mechanism of UA action on the BL oscillating and Duschman non-oscillating reaction systems are discussed in detail.

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The oscillatory Landolt reaction. Empirical rate law model and detailed mechanism

Cited by 59 publications

References 0 publications

DNA nanomachines and their functional evolution

DNA nanomachines and their functional evolution

Modelling iodide – iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

Kinetic analytical method for determination of uric acid in human urine using analyte pulse perturbation technique

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