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A mechanism for the regioselective silaboration of terminal allene by a palladium catalyst has been studied theoretically. The overall reaction scheme has been examined in particular to determine t...

Ti-rich corner (above 50 at.% Ti) of the Ti–Co–Sn system was first studied in the crystallization interval by the methods of microscopy, microprobe, DTA, X-ray diffraction. The liquidus and solidus projections, the melting diagram and the reaction scheme were constructed. No ternary compounds form in the concentration interval studied. The liquidus projection is characterized by the fields of primary crystallization of (βTi) and binary-based phases Ti 3 Sn, Ti 2 Sn, (Ti 5 Sn 3 ), TiCo, Ti 2 Co. The solidus projection is characterized by four three-phase fields: (Ti 3 Sn) + (Ti 2 Sn) + (Ti 5 Sn 3 ), (Ti 3 Sn) + (Ti 5 Sn 3 ) + (TiCo), (βTi) + (Ti 3 Sn) + (TiCo) and (βTi) + (TiCo) + (Ti 2 Co). Three-phase fields form due to invariant four-phase equilibria L U1 + (Ti 2 Sn) ⇄ (Ti 3 Sn) + (Ti 5 Sn 3 ), L U2 + (TiCo) ⇄ (βTi) + (Ti 2 Co), L E1 ⇄ (Ti 3 Sn) + (Ti 5 Sn 3 ) + (TiCo) and L E2 ⇄ (Ti 3 Sn) + (βTi) + (TiCo) at 1230, ∼1040, 1210 and 1050 °C, respectively. In the two-phase fields (Ti 3 Sn) + (TiCo) and (βTi) + (TiCo) there are temperature maxima at ∼1250 and ≳1050 °C, respectively, which form by invariant three-phase equilibria l e3 ⇄ (Ti 3 Sn) + (TiCo) and l e4 ⇄ (βTi) + (TiCo) at ∼1250 and ≳1050 °C, respectively.

A practical and efficient protocol has been developed to realize the catalytic rearrangement of allyl but-3-enoate to heptadienoic acids in NaHCO 3 saturated water, in the presence of catalytic amounts of a rhodium(I) complex, containing olefin, diene or phosphine ligands. The reaction mainly affords the sodium salt of E -2,6-heptadienoic acid, with high catalytic efficiency (3600 TON). A reaction scheme of the process is proposed. The reaction course differs from that observed in organic solvents, where E -3,6-heptadienoic acid is formed predominantly.

Reaction of C6H5NCS with MoS 4 2 - led to the formation of a dinuclear complex of molybdenum(V) with two dithiocarboimidate ligands, (NEt4)2[Mo2(S)2(μ-S)2(η2-S2CN(C6H5))2] · 0.5CO(CH3)2. The crystallization of 1 is systematically accompanied by the formation of 4-phenyl-3,5-diphenylimino[1,2,4]-dithiazolidine [(C6H5)3N3C2S2] (2). The two compounds have been structurally characterized by XRD and a reaction scheme is proposed.

An approach to identify environmental impact reduction alternatives is presented for chemical reaction processes. The primary tools used in this approach are potential environmental impact (PEI) reaction scheme and PEI change due to reaction. A PEI reaction scheme can be used to visualize the transformation relationships among different types of PEI, and can be applied to aid in identifying the sources of environmental impacts and generating alternatives for reducing the impacts. PEI change due to reaction can be used to indicate the change in PEI when this reaction proceeds by one mole of reaction. With the aid of the PEI reaction scheme and the PEI change due to reaction as well as some heuristics, the chemicals and reactions responsible for the potential impacts in the various impact categories can be identified and environmental impact reduction alternatives for a reaction process can be derived. The environmental performance of each alternative is evaluated by doing a quantitative PEI balance. In the case study, the alternatives, which can reduce the output of PEI and the magnitudes of the fresh feeds as well as increase the selectivity of the product, are obtained by using the approach.

The kinetic peculiarities of CO oxidation on WO3 promoted with Pt or Pd were studied. In the region of low catalyst activity (the degree of CO conversion below 20%), the reaction was found to be zero-order in CO and first-order in oxygen. In the high-activity region (CO conversion above 95%), the reaction order was first with respect to CO and zeroth with respect to oxygen. Hysteresis phenomena were observed for the r − c(O2) and r − c(CO) dependences at certain temperatures. A reaction scheme combining the heterogeneous and heterogeneous-homogeneous mechanisms was suggested.

A simple growth model is proposed on the basis of the reaction scheme for the conversion of glucose to gluconic acid. The model considers the combined effects of both glucose and oxygen substrates. Kinetic analysis of the system has been made. Computer solution of the equations proposed are obtained and the adequacy of the models confirmed.

The kinetics of the oxidation of carbon monoxide over five commercially available oxide catalysts have been determined at CO concentrations of 4–15 mol% and initial temperatures up to 170°C. The reaction showed a fractional dependence on the concentration of CO and was inhibited by CO2. From an analysis of the data a Langmuir-Hinshelwood reaction scheme is proposed.

The degree of lability of a given metal complex species is modified in the presence of a mixture of ligands. This modification is a consequence of the coupling of the association and dissociation processes of all of the complexes according to the competitive complexation reaction scheme. We show that, because of the mixture effect, the lability of a given complex usually increases when another more labile complex is added into the system, while it decreases upon addition of a less labile one. Typically, complexes tend to adapt to the global lability of the mixture. A quantitative evaluation of these effects for diffusion-limited conditions in a finite domain by rigorous numerical simulation in a system with two complexes indicates that the lability degree of a complex can change by more than 100% with respect to that in the single ligand system. The impact of the mixture effect on the metal flux depends at least on two main factors: the respective abundance of the metal species and the particular values of their lability degrees. Dominant complexes (i.e., those most abundant when these complexes have equal diffusion coefficients) undergo smaller changes in their own lability degree, but these changes have the greater impact on the overall metal flux. Partially labile complexes are more easily influenced by the mixture than labile or inert ones. Some mixture effects can be qualitatively predicted by an analytical expression for the lability index derived using the reaction layer approximation. For a mixture of many complexes, the change in the lability degree of a complex due to the mixture effect can be understood as a combination of the changes due to all of the complexes present.

An expeditious, high yield and convenient synthesis of Imatinib was carried out on an aldehydic, super acid-sensitive resin, through an efficient, microwave-assisted synthetic protocol. The high versatility of the reaction scheme may enable the straightforward preparation of libraries of potential protein kinase inhibitors endowed with large molecular diversity.

There is a fundamental conflict between two different views of how proteins fold. Kinetic experiments and theoretical calculations are often interpreted in terms of different population fractions folding through different intermediates in independent unrelated pathways (IUP model). However, detailed structural information indicates that all of the protein population folds through a sequence of intermediates predetermined by the foldon substructure of the target protein and a sequential stabilization principle. These contrary views can be resolved by a predetermined pathway--optional error (PPOE) hypothesis. The hypothesis is that any pathway intermediate can incorporate a chance misfolding error that blocks folding and must be reversed for productive folding to continue. Different fractions of the protein population will then block at different steps, populate different intermediates, and fold at different rates, giving the appearance of multiple unrelated pathways. A test of the hypothesis matches the two models against extensive kinetic folding results for hen lysozyme which have been widely cited in support of independent parallel pathways. The PPOE model succeeds with fewer fitting constants. The fitted PPOE reaction scheme leads to known folding behavior, whereas the IUP properties are contradicted by experiment. The appearance of a conflict with multipath theoretical models seems to be due to their different focus, namely on multitrack microscopic behavior versus cooperative macroscopic behavior. The integration of three well-documented principles in the PPOE model (cooperative foldons, sequential stabilization, optional errors) provides a unifying explanation for how proteins fold and why they fold in that way.

Mechanical properties of L1 2 -Co 3 (A1,W) polycrystalline sample are investigated by compression testing at various temperature ranging from room temperature to 1193 K. It was found that at room temperature the 0.2% flow stress is 410 MPa and the compressive ductility is higher than 10%, whereas at 1193K the 0.2% flow stress is 382 MPa and the compressive ductility is about 10%. Two candidates for the reaction scheme of the Co-rich region of the Co-Al-W ternary phase diagram are proposed by combining the results of microstructure observation, X-ray diffractometry and the previous report.

Imidazoline derivatives, a class of novel cationic surfactants are presently gaining importance in global detergent market due to their wide range of applications. These are extensively used mainly as fabric softeners and antistatic agents. The present communication reviews the preparation, reaction scheme, reaction rates and properties of imidazoline derivatives. The analysis of imidazoline derivatives, its mode of action, their biodegradation and various applications have also been discussed.

The effect of ethylene oxide (EO) heterogeneous heterobifunctional acyclic oligomers (HEHAO) on wetting represents a continuation of the review of the research partly published by the author on ethylene oxide (EO) homogeneous heterobifunctional acyclic oligomers (HOHAO). Heterogeneous polyoxyethylene chains obtained by the anionic polymerization of EO (“anionic ring-opening polymerization”) with a certain polydispersity degree are hydrophilic, flexible (specific spatial conformation), biocompatible “bridges,” without toxicity. After the purification of polyethoxylated higher alcohols (technical products), heteroderivatization performed by an adapted classical reaction scheme led to the colloidally evaluated HEHAO series.

A novel synthetic protocol based on an indium-mediated glyoxylate allylation, Heck coupling and Rh-catalysed cyclohydrocarbonylation (CHC) was established to access enantiomerically pure polysubstituted pipecolic acids. The key steps are the Heck reaction, which is performed exclusively using a phenone-oxime derived palladacycle and the domino hydroformylation-cyclisation of a styryl derivative obtained from the Heck coupling. The reaction scheme, proceeding with good stereoselectivity, is also suitable for the preparation of substituted piperidine derivatives.

We study the effect of restart, and retry, on the mean completion time of a generic process. The need to do so arises in various branches of the sciences and we show that it can naturally be addressed by taking advantage of the classical reaction scheme of Michaelis and Menten. Stopping a process in its midst, only to start it all over again, may prolong, leave unchanged, or even shorten the time taken for its completion. Here we are interested in the optimal restart problem, i.e., in finding a restart rate which brings the mean completion time of a process to a minimum. We derive the governing equation for this problem and show that it is exactly solvable in cases of particular interest. We then continue to discover regimes at which solutions to the problem take on universal, details independent, forms which further give rise to optimal scaling laws. The formalism we develop, and the results obtained, can be utilized when optimizing stochastic search processes and randomized computer algorithms. An immediate connection with kinetic proofreading is also noted and discussed.

In the article on the basis of soft measurements concept are described the elements of microbioassay system based on infusorians thermotaxis test reaction: generating test reaction scheme, bioassay factors affecting test reaction, the reaction control system, a computer program for processing digital video, informative parameters.

The kinetics of cyclodextrin (CD) inclusion complexation has been usually analyzed in terms of a one-step reaction or a consecutive two-step reaction involving intracomplex structural transformation as a second step. These schemes presume the inclusion of guest molecules through only one side of the CD cavity and the formation of unidirectional CD complexes. However, there has been increasing experimental evidence for the inclusion of guests through both sides of the CD cavity and the formation of orientational isomers for noncentrosymmetric guest molecules. This article presents a novel parallel reaction scheme for CD inclusion complexation, incorporating bidirectional inclusion and the formation of orientational isomers into the scheme. It is shown that the parallel reaction scheme gives the same concentration versus reaction time relationship as the consecutive two-step reaction scheme. The experimental methods for determining the microscopic directional rate constants are presented. The kinetic parameters of the two-step reaction scheme are expressed as functions of the directional rate constants. The ratios of orientational isomers of alpha-CD-based [2]-pseudorotaxanes and the microscopic directional rate constants of the threading and dethreading reactions are estimated from the reported thermodynamic and kinetics data obtained by using either the one-step or two-step reaction scheme. It is shown that the thermodynamic preference of an isomer over the other is mainly due to the slow dethreading rate of the isomer.

Gas-phase hydrofluorination of perchloroethylene to pentafluoroethane in the presence of a chromium-magnesium catalyst at 0.4 MPa and 330-390°C has been studied. А reaction scheme taking into account the formation of by-products is suggested.

The study is aimed to gain understanding on the mechanism in which Sn and In promoters influence the catalyst deactivation in the course of isobutane dehydrogenation over alumina-supported Pt catalysts. A reaction scheme is postulated envisaging three types of active sites, differing by configuration, adsorption ability, contribution to the reaction routes and vulnerability by coke formations. The model relates the conditions determining the stepwise character of catalyst deactivation earlier observed with the surface fractions of acting types of sites. The approach suggests associating the kinetics of coke formation with the types of sites engaged in the structure of coke precursors.

1-[4-Aminoarylpyrazolo[3,4-b]pyridin-5-yl]pyridinium chlorides undergo cyclization under reflux in tert-butanol in the presence of an excess of potassium tert-butoxide to form tetracyclic derivatives of pyrazolo[3,4-b]pyrido[1′,2′:1,2]imidazo[4,5-d]pyridine. The reaction scheme of the processes is proposed. The structures of the reaction products were confirmed by physicochemical methods.

Photoinduced structural variations in single crystals of 2,4-dichloro-trans-cinnamic acid (C 9 H 6 Cl 2 O 2 , DiCICA) have been investigated using X-ray diffraction (photocrystallography) and optical spectroscopic methods. During UV irradiation, which initiates the irreversible dimerization reaction, a loss of the long-range order of the reactant single crystal was found, i.e., that the dimerization is a heterogeneous one. This unexpected result emphasizes the still-existing problem of predicting changes or of remaining periodicity during chemical reactions in the solid state. On the basis of the experimental results, we propose a qualitative kinetic reaction scheme for DiClCA heterogeneous dimerization reaction.

Catalytic oxidation of monochlorobenzene (667 ppm) in wet air was investigated over PtHFAU(5) catalysts, differing by their Pt content (from 0 to 1.1 wt.%), their Pt dispersion (for identical Pt content) and the electronic state of Pt. PtHFAU(5) catalysts show a higher activity compared to more conventional PtAl2O3 and PtSiO2 samples. For a given temperature, chlorobenzene oxidation over PtHFAU(5) is independent of the platinum particles size. On the other hand, a plateau in activity is reached from 0.4 to 0.6% Pt. Amount of polychlorinated benzenes (PhCl2+) were produced in the order PtAl2O3 > PtSiO2 > PtHFAU(5). The formation of these compounds, especially PhCl2, over PtHFAU(5) was function on the Pt content (PhCl2 isomers appear only from 0.6% PtHFAU), and of the electronic state of Pt. Thus PhCl2, were mainly found over reduced Pt0 particles certainly through a chlorination of platinum (formation of PtClx species). A reaction scheme for the PhCl2 formation was proposed.

A fundamental mathematical model of the tuyere in a blast furnace has been developed earlier. In this study, the model is mainly used to predict the combustion reactions in the tuyere when coke oven gas is injected through lances located inside the tuyere. The combustion reaction is modelled using a simple reaction scheme with 3 possible reactions that can occur. The influence of the following parameters on the predicted velocities, temperatures and composition of the gas at the tuyere outlet is studied in this paper: (i) injection amount of coke oven gas, (ii) the use of 1 or 2 injection lances and (iii) the influence of the injection angles when using 2 injection lances. It is concluded that the maximum injecting amount using 1 and 2 lances is 10,000 nm 3 /h and 15,000 m 3 /h, respectively. The combustion conditions are better when using 2 injection lances are compared to 1 injection lance and the predicted results are not affected to a large degree when the injection angles are changed.

The influence of tobacco type on the selected volatile products of smoke from pyrolyzing tobacco has been investigated by means of a concentrated-parameter model for the conservation of volatile species masses and enthalpies. Pyrolysis products are formed via a reaction scheme based on a large number of parallel first-order reactions with a distributed activation energy expressed by a Gaussian distribution function. The dynamics of volatile species evolution was presented, and the ratio of the smoldering (sidestream) to puffing (mainstream) for the yields of some selected volatile species was simulated which reasonably compares with the existing experimental data.

The liquidus and solidus surfaces of Al–Pd–Fe were determined between 50 and 100 at.% Al. Fifteen ternary reactions involving the liquid phase were revealed: seven peritectic and eight transition reactions. The lowest temperature of the liquid phase corresponds to the binary Al–Pd eutectic. We also report on the five solid-state four-phase transformations in this compositional range from 750 °C up to subsolidus temperatures.

Knowledge of the mathematical properties of the quasi-chemical model [Taub, Feeherry, Ross, Kustin, Doona, 2003. A quasi-chemical kinetics model for the growth and death of Staphylococcus aureus in intermediate moisture bread. J. Food Sci. 68 (8), 2530-2537], which is used to characterize and predict microbial growth-death kinetics in foods, is important for its applications in predictive microbiology. The model consists of a system of four ordinary differential equations (ODEs), which govern the temporal dependence of the bacterial life cycle (the lag, exponential growth, stationary, and death phases, respectively). The ODE system derives from a hypothetical four-step reaction scheme that postulates the activity of a critical intermediate as an antagonist to growth (perhaps through a quorum sensing biomechanism). The general behavior of the solutions to the ODEs is illustrated by several examples. In instances when explicit mathematical solutions to these ODEs are not obtainable, mathematical approximations are used to find solutions that are helpful in evaluating growth in the early stages and again near the end of the process. Useful solutions for the ODE system are also obtained in the case where the rate of antagonist formation is small. The examples and the approximate solutions provide guidance in the parameter estimation that must be done when fitting the model to data. The general behavior of the solutions is illustrated by examples, and the MATLAB programs with worked examples are included in the appendices for use by predictive microbiologists for data collected independently.

position (parallelism) of these problems rather than the CPU time reduction in solving inverse problems. Parallelism is meant to be partition of the entire prob� lem into subproblems of lower dimension. Analysis of these subproblems significantly increases the reliabil� ity of the solution of inverse problems. The possibili� ties of such “internal parallelisms” should follow from the physical content of the problems to be solved. The major problem solved in this work is to create a method that can significantly simplify study of the information content of kinetic models of complex reactions. This method is based on the graph theoreti� cal analysis [4] of independent routes [5, 6]. Analysis of the information content of a complex reaction scheme consists in analysis of the information content of the schemes responsible for the reaction that occurs along each of the independent routes. Instead of one complex system, we deal with several significantly simpler systems. The number of simplified systems is equal to the number of independent routes.

A convenient and rapid synthesis of 4‐(R)‐(naphthalen‐2‐yloxy)‐1‐(1‐phenyl‐(S)‐ethyl)‐pyrrolidin‐3‐(R)‐ol and 4‐(S)‐(naphthalen‐2‐yloxy)‐1‐(1‐phenyl‐(S)‐ethyl)‐pyrrolidin‐3‐(S)‐ol is disclosed. The reaction scheme is highlighted by the meso‐epoxidation of 1‐(1‐phenyl‐(S)‐ethyl)‐2,5‐dihydro‐1H‐pyrrole followed by addition of 2‐naphthol alkoxide to provide both expected diastereoisomers. Separation of the diastereoisomers by crystallization provided access to both diastereoisomers in modest yield without the employment of expensive chiral catalysts. X‐ray analysis of one of the diastereoisomers led to the unambiguous assignment of each diastereoisomer. These chiral pyrrolidine analogues should be useful as intermediates in natural product, combinatorial/parallel synthesis, and medicinal chemistry.

para-Substituted 2-propynyl benzoates are more reactive than the corresponding allyl esters in the Diels-Alder reactions with hexabromo- and tetrabromo-5,5-dimethoxy-1,3-cyclopentadienes. The cycloaddition is favored by the presence of both electron-donor and electron-acceptor substituents in the aromatic ring, in keeping with the “ neutral” reaction scheme. The reactivity of the addends is likely to be determined not only by their donor-acceptor properties but also by the localization energy.

A convenient preparative approach to previously unknown, highly electrophilic C-phosphorylated N-arylsulfonylimines 1, based on fairly readily accessible α-phosphorylated sulfonamides 5, has been developed. Compounds 1 react with trialkyl phosphites or ethyl diphenylphosphinite in the aza-Perkow reaction scheme to give C,N-diphosphorylated N-dichlorovinylsulfonamides 8. On treatment with O- and S-nucleophilic agents (alcohols, thiols, thiophenols), 1 forms addition products 12 and 15, the functionalized derivatives of α-aminophosphonic acids, while interaction between 1 and mercaptoacetic acid proceeds with intramolecular cyclization of the intermediate adduct to produce the novel 2-phosphorylated thiazolidinones 17. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The gas/solution distribution coefficients, the rate constants of the first stage, the activation parameters of the reactions of benzene, monoalkyl- and polymethylbenzenes, and the products from toluene coupling in the HVO3 – H2SO4 (59.7 wt.%) system were studied. A compensation effect involving the number of substituents in the benzene ring was found. A reaction scheme is proposed.

Thiamine is presently one of the most attractive substrates used for sensitive fluorometric measurements of peroxides. Thiochrome (TC), a highly fluorescent product, is formed in enzyme-mediated oxidations. It is assumed that H(2)O(2) is nearly quantitatively converted to TC. The reaction cannot differentiate H(2)O(2) from many other peroxides such as methylhydroperoxide (MHP); to perform differential measurements, H(2)O(2) can first be selectively destroyed by a suitable catalyst such as MnO(2). In substituting Ag(2)O for MnO(2) to accomplish the selective destruction of H(2)O(2), we achieved the stated objective but were puzzled by a 3-fold increase in the MHP response in the presence of Ag(2)O. It was soon discovered that traces of dissolved Ag(+) and Hg(2+) can dramatically increase the yield of TC in this reaction from either H(2)O(2) or MHP; the normal yield in fact is only 20%. We present here a reaction scheme and kinetic model that adequately describes this behavior and should provide a path to substantially increase the sensitivity of this important assay method.

In situ pH measurement of the self-oscillating Cu(II)-lactate system using an electropolymerised polyaniline film as a micro pH sensor

Phase equilibria of the Cd–Sb–Zn system have been investigated by metallographic examinations, DSC, XRD and WDS measurements. At 250 °C, the ternary diagram shows two three-phase fields, (Zn)+(Cd)+Zn4Sb3 and (Cd)+ Zn4Sb3+(Zn,Cd)Sb. Continuous solid solution has been found between ZnSb and CdSb. Solubility of Cd in Sb3Zn4 was determined to be about 43 at.%. A variant of the reaction scheme is proposed for the Cd–Sb–Zn system to understand phase relations observed at 250 °C.

On the basis of analyzing kinetic experimental data performed in laboratory integral reactors a lumping kinetic model of the "Zeoforming" process was developed. A reaction scheme of the lumped components was proposed, that was adapted to the technological requirements. The reaction rate constants and activation energies were estimated, that are valid for certain feed compositions. The model is intended for further modeling and optimization of the process.

The AuCl4−–bilirubin (BR) interaction, both in aqueous–basic and methanolic media was studied using u.v.–vis., e.p.r. and 197Au mossbauer spectroscopy. It was established that, during the course of the reaction, multistep redox and complexation processes occur. BR is oxidized according the reaction scheme: Bilirubin (BR) → Biliverin (BVD) → Purpurine (PRN) accompanied with AuIII reduction to Au0 and complexation, resulting in spontaneous formation of an Au3PRN precipitate. By means of quantitative u.v.–vis. spectroscopic studies some of the rates and stability constants wee determined. The most probable reaction scheme is proposed.

The paper considers a mathematically correct approach to define the rate-determining steps, rate-determining parameters as well as the apparent activation energy for steady occurrence of stepwise reactions with a known reaction scheme. Examples of the application of the suggested approach to analysis of simple stepwise reactions linear in respect to intermediates are presented.

A recent study with single molecule measurements has reported that myosin II, a molecular motor, generates stochastic and multiple steps during the hydrolysis of a single ATP molecule. In order to elucidate the mechanism for the motion of myosin, we traced the movements of individual molecules by simulating the Brownian movements along the potentials created by the interaction between a myosin molecule and an actin filament. We demonstrated that Brownian movement was biased to one direction as observed for myosins by either spatially tilting or temporally fluctuating the height of the potential. We incorporated the biased Brownian movement into an ATP hydrolysis reaction scheme and studied the effects of the load on the movement. The results could successfully explain the movements and mechanical properties of myosin. Thus, it was demonstrated that the movement of myosin is thermally driven and the random motion is biased by the energy released from the ATP hydrolysis.(Communicated by Fumio OOSAWA, M. J. A., Jan. 14, 2003)

Reference EPFL-ARTICLE-180498doi:10.1021/jp3061653View record in Web of Science Record created on 2012-08-09, modified on 2017-12-03

Recently, a new burner was designed by Zhang et al. (Proc. Combust. Inst. 34 [2013], 763-770) to enable the investigation of 1D, premixed flames at atmospheric pressure with a temperature in the burnt gases near 1500 K. It consists of a matrix burner plate with alternating fuel and oxidiser feeds that, because of small-scale nozzles, mix quite rapidly. Flames at high dilution and reduced temperatures such as realised here are of relevance for the understanding of low-temperature combustion strategies. In this work, we examine the burner with regard to the validity of the 1D assumption for the investigated flames. Experimental measurements are conducted and 1D and 3D simulations are performed in which the chemistry is described by a detailed chemistry approach based on a reduced reaction scheme derived from the mechanism of Fischer et al. (Int. J. Chem. Kinetics 32 [2000], 713-740). The experimental results are compared to 1D simulations with two different temperature treatments. First, the unburnt temperature is set to the measured temperature closest to the burner surface; second, the experimental temperature profile is prescribed in the whole simulation domain without solving the energy equation. The comparison shows that the 1D simulation predicts the experimental results reasonably well, if the experimentally obtained temperature profile is prescribed in the simulation domain. Differences are found in the mole fractions of methyl and formaldehyde. Further comparisons of the experimental data with 3D simulation results and comparisons of 3D and 1D simulation results indicate that the differences between measured and computed mole fractions of these species are not a result of the 3D nature of the experimental flame and might be attributed to the chemical mechanism. The conclusion is that the measurement data can be used for validation purposes with the 1D simulation setup shown here if the measured temperature profiles are prescribed in the 1D simulation domain.

A study was carried out to develop a kinetic model of the photocatalytic inactivation of Escherichia coli using different TiO2 catalysts. The model developed is based on a reaction scheme that involves effectively coupling mass-transfer fluxes between bacteria and catalyst surface on one hand and bacterial degradation reaction on the other. The photocatalytic results were derived from experiments led in a batch reactor under both dark and Ultra Violet (UV) irradiation conditions. Using a reference catalyst, the robustness of the developed model was tested under solar conditions. The experimental data validated the model as successfully able to reproduce evolutions in the viable bacteria concentration in the range of parameters studied without any further adjustment of the kinetic parameters. The model was used to simulate the bacterial degradation kinetics under different working conditions to describe the partitioning of both bacterial adhesion and photocatalytic reaction in the solution to be treated © 2015 American Institute of Chemical Engineers AIChE J, 61: 2532–2542, 2015

Herein, we disclose the intriguing story of the structural elucidation of an organic molecule that gave a highly unexpected structure in an apparently well-predictable chemical reaction. Due to the interplay of a multitude of misleading and distracting factors, including the fact that the compound had broad NMR signals due to conformational exchange and had the same nominal mass as the expected molecule, in a first (routine) approximation, its structure seemed to correspond to the expected molecule. Only a deeper investigation, initiated by some further unexpected events in relation to this reaction scheme, revealed the true structure of the compound. This story demonstrates how easy it can be to misinterpret experimental data when one subconsciously seeks to confirm expectations (see Trap #29), especially in a time-pressed industrial research environment; it is also a story of the battle between emotycal and rational minds.

The basic reaction scheme due to Han and co-workers for NR vulcanized with sulphur is adopted and modified taking into account the single contributions of the different accelerators, focusing in particular on some experimental data ad hoc obtained at Pirelli’s laboratories, where NR was vulcanized at different temperatures (from 150 to 180 °C) and concentrations of sulphur, using TBBS and DPG in the mixture as co-agents. Typically, the chain reactions are initiated by the formation of macro-compounds that are responsible of the formation of the unmatured crosslinked polymer. This first reaction depends on the reciprocal concentrations of all components and their chemical nature. In presence of two accelerators, it was considered that the reactions between each single accelerator and the NR raw material occur in parallel, making the reasonable assumption that there are no mutual reactions between the two accelerators. From the kinetic scheme adopted, a closed form solution was found for the crosslink densi...

The consecutive-competing iodide–iodate reaction scheme has been used to study micromixing phenomena in a baffled vessel of 0.29 m diameter agitated by a Rushton turbine. It has been confirmed that, by using successive injections, this reaction scheme is very efficient for such a study. Four agitator speeds giving mean specific energy dissipation rates, e T from ∼0.2 to ∼ 1.2 Wkg −1 have been used, with sub-surface feeding at one of four points. For a given speed, addition at each of these four points gave different local values of e ¯ T, ranging from less than e ¯ T very close to the top of the liquid to much greater close to the impeller. The point closest to the impeller was chosen to be such that feeding was estimated to be at the point of maximum e T. For the maximum speed, the segregation index, as a measure of the amount of ’waste product’, was ∼20% with feed at the top of the liquid (as preferred industrially because of its convenience). This ’waste’ was reduced to ∼5% by feeding at the point of maximum e T close to the impeller. A comparison was also made with results reported in the literature using the same reaction for two new devices developed for improved micromixing. By feeding at the carefully chosen position close to the impeller, the results with the Rushton turbine were as good as or better than with the special devices even at the comparatively low e ¯ T of ∼ l.2 Wkg−1. It was estimated that the maximum local specific energy dissipation rate was ∼70 times the mean, in reasonable agreement with a very recent study where the same pair of reactions and LDV were both used.