Stirring conditions

A dramatic increase of particle size occurs at around pH = 8. At the higher pH(>8), all precipitated particles were within the size range below 1.9 pm, whereas at lower pH(<8), 60-80%wt of particles were larger than 10 pm. The critical pH value is common to all other stirring conditions. The formation of larger particles was avoided by stopping the chemical reaction before the pH value declined to 8. 

The values of that can be realized experimentally vary between 5 X 10 " cm/s (natural convection) and 2 X 10 cm/s (rotating-disk electrode at/= 10,000 rpm). Therefore, reactions for which 10 cm/s will remain reversible whatever the stirring intensity. Such reactions are called completely reversible ( very fast ). Reactions with 10 cm/s will always be irreversible and are called completely irreversible ( very slow ). In the region of intermediate values of the constant, the character of the reaction will depend on stirring conditions. With other values of a and of ratios idfJid,on the boundaries between the various regions of electrode operation will shift slightly, but the overall picture of the phenomena remains the same. 

Br-PADAP showed a significant adsorption at the interface of heptane-water under high-speed stirring conditions (5000 rpm). At the toluene-water interface, the... 

The rate decreases towards the end of the reaction which suggests the rate is dependent on the concentration of dichloride. This was confirmed by decreasing the concentration of HMDS by a factor of three, whilst keeping the sodium constant, when it was found that under comparable stirring conditions the fraction reaction curves nearly coincided. A slightly longer induction period with the lower monomer being consistant with a slower build up of the reaction centers at this concentration. 

Procedure Effects of ultrasound on the following reaction can be seen clearly, when the reactions are carried out both in the ultrasonic field as well as under normal conditions. The yield in most of the reactions increased due to cavitation and mass flow but a decrease could also be sometimes expected due to volatility of one of the reagents. The average increase/decrease in the yield of product, reported here, is an average of two sets of reactions carried out separately under sonicated and mechanical stirring conditions. 

The liquid hydrocarbon stream to be treated may be a crude oil, heavy crude oil, bitumen, or a refined fraction of the crude oil. The hydrogen gas stream is added to the mixture of the hydrocarbon stream with the organic solvent. The reactor, which is fed upflow, is a packed bed of biocatalyst dispersed on a support and is operated at about 74°C. Alternatively, the reactor can also be a batch reactor under stirring conditions. 

All the immobilisations were conducted under stirring conditions at room temperature, then the mixtures were centrifuged for 10 min at 5000 rpm and filtered. The fluorescence of the supernatant was analysed. After a washing treatment, the filtered solution have no evidenced the presence of free protein. The amount of protein adsorbed on the surface was calculated by difference from these protein content data. 

The deposition mechanism of CBD CdZnS thin films under the current stirring conditions are dominated by convection mode (stirring or hydrodynamic transport). In a solution, fluid flow occurs by a natural convection mode... 

They are adapted to other concentrations as suggested by the Hatta number, and estimating that stirring conditions are equivalent to L = 1000 lb/(hr)(sqft). 

Highly crosslinked polymer-supported-BINAPHOS ligands were effective for the hydroformylation of styrene and other functionalized olefins (ee s up to 89%). The catalyst could be recovered and reused at low stirring conditions [61,62]. 

Nonspecific binding Viability of tissue (<30 min) Suboptimal stirring conditions... 

Another sample of soil was analysed at the same RDE, under the same stirring conditions, but in this case a current of 1.76 mA was recorded. What was the concentration of herbicide in the analyte sample ... 

The Bouveault reaction is the preparation of an aldehyde by a one pot reaction between an organic halide and lithium metal in dimethylformamide. Ultrasound has been found to markedly enhance this reaction when it is performed in tetrahydrofuran [93]. Use of an ultrasonic bath at 10-20 °C affords short reaction times of between 5 and 15 min and generates yields in the range 70-88%. Using this methodology the conversion of 1-bromobutane to pentanal (88%) can be achieved in only 5 minutes. This must be contrasted with the yield of less than 10 % which is obtained under the normal stirred conditions in the same time period. This result confirms that the effect of irradiation goes beyond mere agitation (Eq. 3.11). 

Study of the Crystalline Regions. According to our morphological studies, the crystalline structure of UHMWPE pseudo-gel was different under different sample preparations. For example, spherulites and lamellar single crystal stacks were observed when the pseudo-gel was prepared under quiescent conditions, shish-kebab crystals under stirring conditions, and a mixture of single and shish-kebab crystals under uncontrolled conditions (10). 

The starting material, especially the silica source, and the stirring condition during crystallization were found to affect not only the rate of crystallization but also the crystallization area of high silica zeolites, while water content in a reactant mixture was found not to be critical. 

Synthesis conditions H20/Si02 = 20. 180°C for 72 h under stirring condition. 

We have presented a general reaction-diffusion model for porous catalyst particles in stirred semibatch reactors applied to three-phase processes. The model was solved numerically for small and large catalyst particles to elucidate the role of internal and external mass transfer limitations. The case studies (citral and sugar hydrogenation) revealed that both internal and external resistances can considerably affect the rate and selectivity of the process. In order to obtain the best possible performance of industrial reactors, it is necessary to use this kind of simulation approach, which helps to optimize the process parameters, such as temperature, hydrogen pressure, catalyst particle size and the stirring conditions. 

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