Effect of Initial Reactant Temperature on Flame Speeds in Aluminum Dust Suspensions

2020 ◽  
pp. 1-14
Author(s):  
Frederic Blais ◽  
Philippe Julien ◽  
Jan Palecka ◽  
Samuel Goroshin ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Initial Reactant

Pattern Formation in the Methylene Blue-Fructose-Oxygen System in Aqueous Solution and in Gel Systems

2000 ◽  
Vol 65 (9) ◽  
pp. 1394-1402 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Mária Hupková ◽  
Peter Ševčík
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Pattern Formation ◽  
Alkaline Ph ◽  
Initial Reactant ◽  
Nonlinear Reaction ◽  
Oxygen System ◽  
Hydrodynamic Processes ◽  
Liquid Layer Thickness ◽  
Catalyzed Oxidation

Spatial patterns in methylene blue-catalyzed oxidation of fructose at alkaline pH were found in aqueous solution and in gel systems. In a thin liquid layer (thickness >2.4 mm) a mixture of spots and stripes was formed by interaction of a nonlinear reaction and the Rayleigh or Maragoni instabilities. The pattern formation was affected by initial reactant concentrations and by the thickness of the reaction mixture layer. Long-lasting structures were formed in gel systems (polyacrylamide, agar, gelatin). These patterns also arise primarily from hydrodynamic processes.

The Reactions of Organometallic Compounds Involving Silicon. Reactions of Triphenyl-, Diphenylmethyl-, and Phenyldimethylsilyl-lithium with 9-Phenylfluorene in Tetrahydrofuran

1972 ◽  
Vol 50 (23) ◽  
pp. 3761-3766 ◽  
Author(s):  
M. A. Hamid
Keyword(s):  
Low Temperatures ◽  
Initial Rate ◽  
Organometallic Compounds ◽  
Initial Reactant ◽  
Thermodynamic Constants ◽  
Rate Of Reaction ◽  
Stop Flow

Triphenyl-, diphenylmethyl-, and phenyldimethylsilyl-lithium react very rapidly with 9-phenylfluorene in tetrahydrofuran (THF) but the reaction can be followed spectroscopically using the stop-flow technique at low temperatures. The order of reaction, found from the dependence of the initial rate of reaction on the initial reactant concentrations, is unity in both 9-phenylfluorene and the relevant organosilyl-lithium reagent. The thermodynamic constants of activation for the reaction between 9-phenylfluorene and triphenylsilyl-lithium (Ph3SiLi), diphenylmethylsilyl-lithium (Ph2MeSiLi), and phenyldimethylsilyl-lithium (PhMe2SiLi), respectively, are: ΔH≠ = 4.5, 4.0, and 4.0 kcal mol−1; ΔG≠ = 13.0, 12.5, and 12.5 kcal mol−1; ΔS≠ = −34.9, −34.8, and −34.9 cal mol−1 deg−1

scholarly journals Stochastic Dynamic Model of Sulfate Corrosion Reactions in Concrete Materials considering the Effects of Colored Gaussian Noises

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Tao Li ◽  
Bin Zhang
Keyword(s):  
Random Process ◽  
Dynamic Model ◽  
Mass Conservation ◽  
Corrosion Products ◽  
Chemical System ◽  
Stochastic Dynamic ◽  
Initial Reactant ◽  
Corrosion Reaction ◽  
Concrete Materials ◽  
Concentration Evolution

The corrosion reactions in concrete materials subjected to external environment attack can lead to the deterioration of concrete. However, the effects of internal fluctuations on the corrosion reaction process have not been reported in current studies on damage of concrete materials. To comprehensively describe the effects of internal fluctuations, the stochastic dynamic model of corrosion reactions in concrete materials subjected to sulfate attack is established based on the law of mass conservation and random process theory, in which internal fluctuations and the parameters of the chemical system are, respectively, regarded as colored Gaussian noises and a series of random variables. An experiment of sulfate corrosion reactions in concrete material is carried out to verify the effectiveness of the proposed method. Furthermore, the effects of variations of the initial reactant concentrations on the concentration evolution processes of the corrosion products are investigated. Results show that the stochastic dynamical responses of the corrosion reactions in concrete can be comprehensively investigated by the proposed stochastic mathematical model; the probabilistic information of the corrosion products can also be obtained conveniently. The concentration evolution process of sulfate corrosion products is a random process. The experimental data are only some samples of the random process. Concentrations of the corrosion products in concrete materials significantly fluctuate with the variations of the initial reactant concentrations.

Laser-Induced Photochemical Reactions of Methanol, Ethanol, 1-Propanol, and 2-Propanol

1988 ◽  
Vol 42 (7) ◽  
pp. 1268-1273 ◽  
Author(s):  
R. A. Johnson ◽  
A. E. Stanley
Keyword(s):  
Fourier Transform ◽  
Carbon Dioxide Laser ◽  
Continuous Wave ◽  
Irradiation Time ◽  
Photochemical Reactions ◽  
Output Line ◽  
Time Intervals ◽  
Consecutive Reaction ◽  
Initial Reactant ◽  
Consecutive Reactions

This study focuses on the carbon dioxide laser-induced excitation and resultant dissociation of several members of a group of carbon-oxygen (C-O)-containing molecules, the alcohols methanol, ethanol, 1-propanol, and 2-propanol. The tunable continuous-wave infrared (cw) laser provides the energy of activation necessary for dissociation to occur after absorption into the C-O stretching fundamentals of the alcohols. Chemical reactions were monitored with the use of Fourier transform infrared spectroscopy, also used for identification of end products. After irradiation, ethanol and 1-propanol each yielded acetaldehyde. The products of the dissocation of methanol were carbon monoxide, formaldehyde, and hydrogen. The formaldehyde then reacted with excess methanol to produce methoxymethanol. Fourier transform interferograms were collected at specific time intervals, thus monitoring any consecutive reactions that occurred after the irradiation. For methanol, laser parameters such as output line frequency and power as well as irradiation time were varied. The effect of initial reactant pressure on the laser-induced dissociation of methanol was evaluated. Only methanol underwent a consecutive reaction. Hydrocarbon fragments were also observed from ethanol, 1-propanol, and 2-propanol. Methane, ethene, and ethyne were produced from ethanol. Propene, ethene, and methane were produced from 1-propanol, and methane and propene from 2-propanol. The products observed in some instances were different from those reported in the literature for pyrolytic and pulsed laser studies. The results from these investigations are compared with results from other similar compounds and similar techniques.

scholarly journals From amino acid mixtures to peptides in liquid sulphur dioxide on early Earth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fabian Sauer ◽  
Maren Haas ◽  
Constanze Sydow ◽  
Alexander F. Siegle ◽  
Christoph A. Lauer ◽  
...  
Keyword(s):  
Amino Acids ◽  
Sulphur Dioxide ◽  
Room Temperature ◽  
Early Earth ◽  
Peptide Bonds ◽  
Initial Reactant ◽  
Peptide Formation ◽  
Liquid Sulphur ◽  
Catalytically Active ◽  
Amino Acid Mixtures

AbstractThe formation of peptide bonds is one of the most important biochemical reaction steps. Without the development of structurally and catalytically active polymers, there would be no life on our planet. However, the formation of large, complex oligomer systems is prevented by the high thermodynamic barrier of peptide condensation in aqueous solution. Liquid sulphur dioxide proves to be a superior alternative for copper-catalyzed peptide condensations. Compared to water, amino acids are activated in sulphur dioxide, leading to the incorporation of all 20 proteinogenic amino acids into proteins. Strikingly, even extremely low initial reactant concentrations of only 50 mM are sufficient for extensive peptide formation, yielding up to 2.9% of dialanine in 7 days. The reactions carried out at room temperature and the successful use of the Hadean mineral covellite (CuS) as a catalyst, suggest a volcanic environment for the formation of the peptide world on early Earth.

The kinetics of acrylamide formation/elimination in asparagine–glucose systems at different initial reactant concentrations and ratios

2008 ◽  
Vol 111 (3) ◽  
pp. 719-729 ◽  
Author(s):  
Kristel De Vleeschouwer ◽  
Iesel Van der Plancken ◽  
Ann Van Loey ◽  
Marc E. Hendrickx
Keyword(s):  
Initial Reactant ◽  
Acrylamide Formation ◽  
Kinetics Of

scholarly journals An Overview on the Photocatalytic Activity of Nano-Doped-TiO2 in the Degradation of Organic Pollutants

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Yong Nian Tan ◽  
Chung Leng Wong ◽  
Abdul Rahman Mohamed
Keyword(s):  
Photocatalytic Degradation ◽  
Organic Pollutants ◽  
Doping Concentration ◽  
Anatase Phase ◽  
High Specific Surface Area ◽  
Operating Parameters ◽  
Photocatalytic Efficiency ◽  
Small Crystallite Size ◽  
Initial Reactant ◽  
Small Crystallite

This paper aims to review and summarize the recent works on the photocatalytic degradation of various organic pollutants in the presence of nano-doped-TiO2 photocatalysts. In this regard, three main aspects are examined: (a) the presence of various dopants (metal dopants, nonmetal dopants, halogen dopants, metalloid dopants, and codopants) in the formation of nano-doped-TiO2 photocatalysts, (b) the effect of the presence of dopants on the photocatalytic degradation of organic pollutants, and (c) the effects of various operating parameters on the photocatalytic degradation of organic pollutants in the presence of nano-doped-TiO2 photocatalysts. Reports resulted suggest that the formation of a high percentage of the anatase phase, small crystallite size, and high specific surface area of the nano-doped-TiO2 photocatalysts depends on the presence of various dopants in the photocatalysts. The majority of the dopants have the potential to improve the photocatalytic efficiency of nano-doped-TiO2 in the degradation of organic pollutants. The photocatalytic degradation of organic compounds depends on the calcination temperature of the prepared doped TiO2, initial reactant concentration, dosage of doped TiO2, and dopant doping concentration.

Total Synthesis of C-8 Hydroxyl Substituted Lomefloxacin as the Photolysis Impurity

2021 ◽  
Vol 18 ◽  
Author(s):  
Si Chen ◽  
Ying Wang ◽  
Xiao Yuan ◽  
Laiyou Wang
Keyword(s):  
Total Synthesis ◽  
Solid Phase ◽  
Active Pharmaceutical Ingredient ◽  
Ethyl Acrylate ◽  
Phase Extraction ◽  
Initial Reactant ◽  
Photochemical Decomposition ◽  
The Stability ◽  
Consistency Evaluation ◽  
Methoxybenzoic Acid

Objective: Photochemical decomposition of lomefloxacin (Lom) is supposed to result in the generation of C-8 substituted impurity and accompanied fluoride. The existence and amount of C-8 hydroxyl substituted Lom could be proposed as the marker to the stability and process consistency. The specific C-8 hydroxyl substituent impurity (1-ethyl-6-fluoro-8-hydroxy-7-(3-methylpiperazin-1-yl )-4-oxo-1,4-dihydroquinoline-3-carboxylic acid) was designed and synthesized to be available. Method: 2,4,5-trifluoro-3-methoxybenzoic acid as the initial reactant was subjected to a series of seven-step reactions, such as acylation, condensation with trans N,N-dimethylamino ethyl acrylate, N-ethylation, cyclization, hydrolysis, condensation with piperazine and acidification. The resultant substance was then purified using HPLC and C18 solid-phase extraction. The structure of C-8 hydroxyl substituted Lom was identified with 1H-NMR, 13C-NMR and HRMS spectroscopes, as well as the purity was determined by HPLC. Conclusion: C-8 hydroxyl substituted Lom was successfully synthesized and purified with purity more than 96%. This photolysis impurity offers an alternative for not only further generic Lom active pharmaceutical ingredient development involved in quality control and consistency evaluation, but also research for the mechanism underlying Lom-induced photosensitivity.

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