Ultraviolet (UV)–visible (Vis) spectroscopy is widely used in all modern laboratories as a routine method of analysis. The monitoring of chemical reactions in an aqueous solution involving a gas ...product is a demanding task but particularly for oscillatory reactions which are obtainable in a narrow concentration range. In this work, the optimization of experimental conditions for UV–Vis measurements of the Bray–Liebhafsky (BL) oscillatory reaction producing oxygen was done by using an internal standard. After applying the method of the internal standard on iodine absorbance at 460 nm, the characteristic BL oscillatory parameters (and iodine changes) are clearly evident. The obtained results allow students to apply their existing knowledge and, through a simple experimental setup, understand the importance of the internal standard, but at the same time, they show how they can solve the problem of UV–Vis noise during the time-based measurements of reactions involving gas products in general.
Over the past decade, a large number of jet substructure observables have been proposed in the literature, and explored at the LHC experiments. Such observables attempt to utilize the internal ...structure of jets in order to distinguish those initiated by quarks, gluons, or by boosted heavy objects, such as top quarks and
W
bosons. This report, originating from and motivated by the BOOST2013 workshop, presents original particle-level studies that aim to improve our understanding of the relationships between jet substructure observables, their complementarity, and their dependence on the underlying jet properties, particularly the jet radius and jet transverse momentum. This is explored in the context of quark/gluon discrimination, boosted
W
boson tagging and boosted top quark tagging.
We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of ...highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
The influence of adrenaline on two iodate based oscillating chemical reactions, the Bray–Liebhafsky (BL) and Briggs–Rauscher (BR) reactions was investigated. It was observed that the addition of ...adrenaline has different effects on the examined systems. Its addition to the BR system significantly changes the dynamics, while in the BL system, the presence of adrenaline does not show any effect. In order to find out the cause of such a different response of two similar oscillators, UV/VIS spectroscopy was used. Results obtained from recorded UV/VIS spectra indicated that, from all investigated stable reaction species, adrenaline interacts only with potassium iodate and iodine, which are present in both oscillating reactions. Because of this, the different response of the oscillators cannot be ascribed to the reactions between adrenaline and common iodine (stable and unstable) components. As a result, the considerable response of the BR system to adrenaline may be related to the reactions between adrenaline (or its oxidation products) and non-common derivatives of malonic acid or manganese intermediate species.
The oscillatory behavior is not the only interesting nonlinear phenomena that appeared in the Briggs–Rauscher (BR) reaction. The BR reaction containing malonic acid may undergo a sudden transition ...from low (the state I) to high iodide and iodine (the state II) concentration states. This paper focuses on the mixture with an immutable CH
2
(COOH)
2
0
/IO
3
−
0
= 1.5 value, where state I to state II transition occurs after a time delay and BR reaction ended with a solution abundant of solid iodine. The state I to the state II transition curves obtained at different temperatures were analyzed using the Kolmogorov–Johnson–Mehl–Avrami (KJMA) theory. The KJMA theory was applied for monitoring the crystallization process of isolated solid iodine product at various levels of operating temperatures. At
T
< 33.5 °C, we have one type of the process and iodine was formed by autocatalysis pathway. On the other hand, at
T
≥ 33.5 °C, two processes occur. With the rise in operating temperature, the emergence of inhomogeneous distribution of nuclei was identified and it was established the primary and secondary crystallization processes of iodine. At elevated temperatures, it was also found that the strong influence of impingement mechanism exists. Results obtained are the first step toward elucidation of the complex reaction mechanism of the state I → state II transition.
Indigo carmine is a commonly used industrial blue dye. To determine its concentration in a commercially available food dye composed of a mixture of indigo carmine and D-glucose, this paper ...characterizes it through (ATR, KBr) FTIR micro-Raman as well as UV/Vis and clock: Briggs–Rauscher (BR) oscillatory reaction methods. The indigo carmine was detected in the bulk food dye only by applying micro-Raman spectroscopy, indicating a low percentage of the indigo carmine present. This research provides an improvement in the deviations from the experimental Raman spectrum as calculated by the B97D/cc-pVTZ level of theory one, resulting in a better geometrical optimization of the indigo carmine molecule compared to data within the literature. The analytical curves used to determine indigo carmine concentrations (and quantities) in an aqueous solution of food dye were applied by means of UV/Vis and BR methods. BR yielded significantly better analytical parameters: 100 times lower LOD and LOQ compared to commonly used UV/Vis. The remarkable sensitivity of the BR reaction towards indigo carmine suggests that not only does indigo carmine react in an oscillatory reaction but also its decomposition products, meaning that the multiple oxidation reactions have an important role in the BR’s indigo carmine mechanism. The novelty of this research is the investigation of indigo carmine using a clock BR reaction, opening new possibilities to determine indigo carmine in other complex samples (pharmaceutical, food, etc.).
The calcium phosphate tungsten bronze (Ca-PWB) has been synthesized and
characterized (TGA, DSC, XRPD, FTIR, SEM). The influence of solid insoluble
materials Ca- PWB, as well as lithium doped ...(Li-PWB) and cation free
phosphate tungsten (PWB) bronzes on the oscillatory Briggs-Rauscher (BR)
reaction dynamics, is compared. The results show that doping with Li and Ca
reduces sensitivity of the BR reaction towards bronzes addition. These
findings suggest the usage of the BR reaction as an innovative method for
testing of different properties of bronze material. The behavior of PWB in
the BR reaction is significantly changed with divalent cation (Ca2+) doping.
The reasons for the different bronzes behavior were found in their
calculated unit cell volumes. Namely, the compressed Ca-PWB unit cell volume
indicates the difficult availability of the active site for heterogeneous
catalysis. Hence, the linear correlation (slope) of the BR oscillogram?s
length (?osc) vs. mass of bronze in BR reaction might be considered as a new
parameter for the evaluation of the bronzes catalytic activity.
Perturbation of the BrayLiebhafsky non‐oscillating subsystem (mixture of KIO3 and H2SO4), i.e., Dushman reaction (DR), by piroxicam (PX), was observed in an open reactor, i.e., in the continuously ...fed well‐stirred tank reactor (CSTR). Monitoring the response of DR to perturbations by different concentrations of PX allows developing a simple procedure for quantitative determination of this analyte in both bulk drug and pharmaceutical preparation (injection). A tentative perturbation mechanism of PX action on the DR matrix, based on a kinetic scheme that was suggested by Agreda et al., is proposed. The PX reactivity in DR has been generally related to the reaction of PX with hypoiodous acid (HIO) present in the matrix.
The Briggs–Rauscher reaction containing malonic acid may undergo a sudden transition from low (state I) to high iodide and iodine (state II) concentration states after a well-defined and strongly ...reproducible oscillatory period. This study clearly shows that even though the time-dependent behavior of the oscillatory state is reproducible, the time lag necessary for the appearance of the state I to state II transition after the system leaves the oscillatory state becomes irreproducible for an individual kinetic run. This crazy clock behavior of the state I to state II transition is identified by repeated experiments in which stirring rate is taken as a control parameter and all other parameters such as initial conditions, temperature, vessel surface, and the age of solution were kept constant. Surprisingly, a better stirring condition does not make the transition reproducible; it simply does not allow the transition to happen at all. The proposed mechanism, additional explanations, and proposals for this irreproducibility of state I to state II transition have been presented. Considering the fact that the number of crazy clock reactions is only a few, this study may contribute to a better understanding of fundaments of this phenomenon.
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