INDUCTION PERIODS IN REACTIONS BETWEEN THIOSULFATE AND ARSENITE OR ARSENATE:1A USEFUL CLOCK REACTION.

Aflatoxin B1 (AFB1), a pollutant of agricultural products, has attracted considerable attention in recent years, due to its potential impact on health. In the present study, Bacillus licheniformis (BL010) was demonstrated to efficiently degrade AFB1, reducing over 89.1% of the toxin content within 120 h. A crude enzyme solution of BL010 exhibited the highest degradation level (97.3%) after three induction periods. However, uninduced BL010 bacteria was not capable of reducing AFB1. Furthermore, high performance liquid chromatography (HPLC) analysis showed that while a cell-free extract caused a significant decrease in AFB1 content (93.6%, p < 0.05), cell culture fluid treatment did not significantly degrade AFB1. The biotransformation products of AFB1 were detected and further identified by quadrupole time-of-flight liquid chromatography–mass spectrometry (LC-Q-TOF/MS); these corresponded to a molecular formula of C12H14O4. A sequence analysis of whole BL010 genes with a bioinformatics approach identified the secondary structures of two degrading enzymes (Chia010 and Lac010), providing an important basis for subsequent homology modeling and functional predictions.

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Replacing sulfonate by carboxylate: application of pyridyliminocarboxylato copper(II) complexes in rac-lactide polymerization and Chan–Evans–Lam coupling

Canadian Journal of Chemistry ◽

10.1139/cjc-2018-0402 ◽

2019 ◽

Vol 97 (3) ◽

pp. 178-190 ◽

Cited By ~ 2

Author(s):

Valérie Hardouin Duparc ◽

Clémentine Dimeck ◽

Frank Schaper

Keyword(s):

Molecular Sieves ◽

Weight Control ◽

Phenylboronic Acid ◽

Side Reactions ◽

X Ray Diffraction ◽

Reaction Conditions ◽

One Pot ◽

X Ray ◽

Induction Periods ◽

Lactide Polymerization

Copper(II) complexes carrying pyridylmethyleneaminobenzoate or –propanoate ligands, LCuX, were prepared in one-pot reactions from pyridinecarboxaldehyde, aminobenzoic acid or β-alanine, and CuX2 (X = Cl, NO3, OAc, or OTf). All complexes were characterized by single-crystal X-ray diffraction studies and formed either dimers, tetramers, or coordination polymers. Attempted preparation of the respective alkoxide complexes, LCu(OR), was unsuccessful, but use of LCuX/NaOMe mixtures in rac-lactide polymerization indicated under some conditions coordination–insertion polymerization via a copper alkoxide as the mechanism. The complexes performed poorly in rac-lactide polymerization, showing low activities (12 h to completion at 140 °C), low to moderate heterotacticity (Pr = 0.6–0.8), and poor polymer molecular weight control (intramolecular transesterification). They were competent catalysts for Chan–Evans–Lam couplings with phenylboronic acid, without any indication of side reactions such as deboration or aryl homocoupling. The complexes were active in undried methanol, without addition of base, ligand, or molecular sieves. Aniline, n-octylamine, and cyclohexylamine were coupled quantitatively under identical reaction conditions. There is only little influence of the anion on activities (less than a factor of 2) but a strong influence on induction periods. The complexes were not active in CEL coupling with alcohols, phenols, or alkylboronic acids.

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A mathematical model of the cool-flame oxidation of acetaldehyde

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1971.0074 ◽

1971 ◽

Vol 322 (1550) ◽

pp. 377-403 ◽

Cited By ~ 41

Keyword(s):

Mathematical Model ◽

Negative Temperature ◽

Isothermal Oxidation ◽

Limited Range ◽

Detailed Model ◽

Cool Flame ◽

Induction Periods ◽

Cool Flames ◽

Satisfactory Account ◽

Flame Oxidation

A detailed mathematical model of the non-isothermal oxidation of acetaldehyde has been found to give a realistic simulation of (i) single and multiple cool flames, their limits, amplitudes and induction periods; (ii) two-stage ignition; and (iii) the negative temperature coefficient for the maximum rate of slow combustion. A simplified form of the model, valid over a limited range of conditions, has been subjected to mathematical analysis to provide interpretations of the effects simulated by the detailed model. It is concluded that cool flames are thermokinetic effects often, but not exclusively, of an oscillatory nature, and that a satisfactory account of cool-flame phenomena must necessarily take reactant consumption into account.

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On the Mechanism of Radical Polymerization of Methyl Methacrylate with Dithiobenzoic Acid as Mediator

Australian Journal of Chemistry ◽

10.1071/ch06158 ◽

2006 ◽

Vol 59 (8) ◽

pp. 549 ◽

Cited By ~ 13

Author(s):

Duc Hung Nguyen ◽

Philipp Vana

Keyword(s):

Methyl Methacrylate ◽

Induction Period ◽

Hydrogen Abstraction ◽

Ester Group ◽

Reaction Scheme ◽

Ionization Mass ◽

Controlled Polymerization ◽

Induction Periods ◽

Methyl Methacrylate Polymerization ◽

Raft Agent

Dithiobenzoic acid (DTBA) induces controlled polymerization behaviour in methyl methacrylate polymerization at 60°C, accompanied by a pronounced induction period of several hours. DTBA is partially transformed during this induction period into a dithioester with a tertiary ester group moiety, which constitutes an efficient reversible addition–fragmentation chain transfer (RAFT) agent. The transformation reaction is proposed to proceed via a hydrogen abstraction from DTBA by radicals and subsequent termination of the formed phenylcarbonothioylsulfanyl radical with propagating radicals. The proposed reaction scheme was implemented into a computer model, by which the rate coefficient of the hydrogen abstraction from DTBA and of the reinitiation of the intermediate phenylcarbonothioylsulfanyl radical was estimated. The model is in agreement with all of the species observable by electrospray ionization mass spectrometry, with the extent of the experimental induction periods, and with the absolute concentrations of dithioesters that act as efficient RAFT agents during the polymerization. A protocol that uses a cocktail of initiators is introduced, by which the induction period in DTBA-mediated polymerization is effectively eliminated.

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Kinetic Studies of Ammonia Oxidation in Shock Waves. IV. Comparison of Induction Periods for the Ignition of NH3-O2-N2with Those for NH3-O2-Ar Mixtures

Bulletin of the Chemical Society of Japan ◽

10.1246/bcsj.41.1761 ◽

1968 ◽

Vol 41 (8) ◽

pp. 1761-1765 ◽

Cited By ~ 9

Author(s):

Hajime Miyama

Keyword(s):

Shock Waves ◽

Ammonia Oxidation ◽

Kinetic Studies ◽

Induction Periods

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The behaviour of additives in explosions and the mechanism of antiknock. I

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1960.0227 ◽

1960 ◽

Vol 259 (1298) ◽

pp. 304-324 ◽

Cited By ~ 15

Keyword(s):

The Other ◽

Manganese Compound ◽

Tin Compounds ◽

Induction Periods ◽

Auto Ignition ◽

Metal Additives ◽

Manganese Tricarbonyl ◽

Absorption And Emission Spectroscopy ◽

Manganese Compounds ◽

Iron And Manganese

The behaviour of Te Me 2 , I 2 , Si Me 4 , Sn Et 4 , methyl cyclo pentadienyl manganese tricarbonyl ( AK -33X), Fe(CO) 5 , ferrocene, Hg vapour and Hg ( iso -propyl) 2 was observed during explosions of amyl nitrite (sensitizer), n -heptane and oxygen. After flash initiation, the reactions were followed by kinetic absorption and emission spectroscopy. The effect of these substances with respect to antiknock action, smoke formation, effect on induction period (preflame reaction) and the emission of light, has been recorded. With the tin and transition metal additives, smokes formed during the induction periods, characterized by a continuous scattering over the entire continuum. A K -33X increased or decreased the induction periods, according to the conditions. TeMe2 and I 2 increased the induction periods by homogeneous reactions. None of the other compounds changed the duration of the induction periods, including the iron compounds which are known to be antiknocks. With the iron and tin compounds included in the charges, smokes formed early in the induction periods and it was therefore concluded that the colloidal solids formed during the combustion of these compounds do not delay auto-ignition by preflame end gas reactions. It follows that there are two mechanisms of antiknock. It is suggested that the occurrence of heterogeneous inhibition is contrary to experience: (a) because there is insufficient surface exposed, (b) because the efficiency of reaction of chain centres at surfaces is low, (c) because the other antiknocks, Te Me 2 I 2 and Pb Et 4 act homogeneously. It is proposed that the second mechanism of antiknock, into which category the iron and manganese compounds fall, is a result of the reaction of the additive on the burnt or burning gases, rather than on the unburned gases. An intense emission of infra-red and visible light from explosions containing iron and manganese may be related to their mechanism as antiknocks; it is suggested that the increase in radiative cooling, caused by excitation and fluorescence of gaseous metal oxides and/or specific deactivation of propagating centres by metal or metal oxide species, plays an important role in this effect. The manganese compound also exhibits antiknock properties of the first type.

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Isothermal Crystallization Behavior of Poly (L-lactic Acid)/ Surface-Grafted Silica Nanocomposites

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.268-270.37 ◽

2012 ◽

Vol 268-270 ◽

pp. 37-40 ◽

Cited By ~ 1

Author(s):

Yan Hua Cai

Keyword(s):

Lactic Acid ◽

Isothermal Crystallization ◽

Crystallization Behavior ◽

Nucleating Agent ◽

Melt Blending ◽

Scanning Calorimetry ◽

Silica Nanocomposites ◽

Induction Periods ◽

Sio2 Nanocomposites ◽

Different Content

The Poly(L-lactic acid)(PLLA)/surface-grafting silica(g-SiO2) nanocomposites were prepared by melt blending. The isothermal crystallization behavior of PLLA/g-SiO2 nanocomposites with different content of g-SiO2 was investigated by optical depolarizer. In isothermal crystallization from melt, the induction periods and half times for overall PLLA crystallization (95°C Tc 120°C) were affected by the crystallization temperature and the content of g-SiO2 in nanocomposites. The results showed that g-SiO2 as a kind of heterogeneous nucleating agent can reduce induction periods and half times for overall PLLA crystallization. The thermal properties of PLLA/g-SiO2 samples were also investigated by differential scanning calorimetry (DSC), The results showed that the crystalline degree of PLLA was improved as the presence of g-SiO2.

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Shock-initiated exothermic reactions. VI. The oxidation of ethylene oxide and cyclopropane

Australian Journal of Chemistry ◽

10.1071/ch9691355 ◽

1969 ◽

Vol 22 (7) ◽

pp. 1355 ◽

Cited By ~ 3

Author(s):

LJ Drummond ◽

J Kikkert

Keyword(s):

Shock Waves ◽

Ethylene Oxide ◽

Shock Tube ◽

Induction Period ◽

Ignition Delay ◽

Exothermic Reactions ◽

Induction Periods ◽

Reflected Shock ◽

Formaldehyde Oxidation ◽

Temperature Dependences

Mixtures of ethylene oxide or cyclopropane with oxygen and argon were ignited with reflected shock waves In a shock tube. The temperature dependences of the ignition delay and the growth of light emitted during the induction period to explosion of C2H4O-O2 mixtures indicate that the rate-controlling reaction is that of formaldehyde oxidation. The temperature dependence of induction periods for C3H6-O2 mixtures suggests that a complicated but undetermined mechanism controls the delay to ignition.

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