Batch techniques

Pad-batch dyeing shows its primary benefits over other methods where it is possible to apply the dye on grey (unbleached) minimally prepared fabric, eg, T-shirts, followed by washing on the same perforated beam used to batch the fabric after dyeing. Where a bleached fabric base is needed, the bleaching is best carried out using peroxide by pad-batch technique in order to ensure an even effect and pick up when padding the dye Hquor. Similarly all other preparation is best carried out in open-width. 

HPLC separations are one of the most important fields in the preparative resolution of enantiomers. The instrumentation improvements and the increasing choice of commercially available chiral stationary phases (CSPs) are some of the main reasons for the present significance of chromatographic resolutions at large-scale by HPLC. Proof of this interest can be seen in several reviews, and many chapters have in the past few years dealt with preparative applications of HPLC in the resolution of chiral compounds [19-23]. However, liquid chromatography has the attribute of being a batch technique and therefore is not totally convenient for production-scale, where continuous techniques are preferred by far. 

The reasons of this behaviour were soon discovered by Schulz team29). One was purely technical. Under the conditions prevailing in the earlier experiments of Schulz and Lohr the polymerization was too slow for employment of the flow technique adopted by the authors in their earlier investigation, but too fast for the conventional batch technique. Development of a stirred reactor allowing studies of reactions with half-lifetime as short as 2 sec eliminated this difficulty 30). 

Fowle and Fein (1999) measured the sorption of Cd, Cu, and Pb by B. subtilis and B. licheniformis using the batch technique with single or mixed metals and one or both bacterial species. The sorption parameters estimated from the model were in excellent agreement with those measured experimentally, indicating that chemical equilibrium modeling of aqueous metal sorption by bacterial surfaces could accurately predict the distribution of metals in complex multicomponent systems. Fein and Delea (1999) also tested the applicability of a chemical equilibrium approach to describing aqueous and surface complexation reactions in a Cd-EDTA-Z . subtilis system. The experimental values were consistent with those derived from chemical modeling. 

Fowle et al. (2000) have measured the sorption by a soil bacterium (B. subtilis) of uranyl in 0.1 M NaC104 at 25°C as a function of pH, time, and solid solute ratio, using a batch technique. The stoichiometiy and thermodynamic stability of the important uranyl-surface complexes indicated that uranyl formed two different surface complexes, one involving neutral phosphate functional groups, and another with deprotonated carboxyl functional groups, on the bacterial cell wall ... 

The first technical process involved heating phthalonitrile with copper bronze or copper(I)chloride at 200 to 240°C in copper pans. Several variations of this technique were developed in Germany prior to the Second World War. The reaction was performed either without or in the presence of a solvent. A basic distinction is commonly made between the baking process and the solvent process both may be carried out either by continuous or by batch technique. 

Since elution is basically a batch technique, continuous production requires cyclic batch operation under automatic control. This is achieved, first, by using repetitive automatic... 

Conclusions. Table II compares some characteristics of the semicontinuous and batch techniques. According to 1H NMR and GPC data the semicontinuous technique produces polymers with well defined symmetrical end groups, while the batchy polymerization may yield once-fired and unfired chain ends. The M Mn values of polymers obtained in semicontinuous runs are close to theoretical, whereas those harvested in conventional batch polymerization exhibit broader molecular weight distributions due to changing [I] and [M], presence of once-fired and/or unfired chain ends, and insufficient reactor control. The latter circumstance may even result in bimodal distributions. 

I and M is possible only in specific cases, while in semicontinuous runs both I and M are completely consumed and constant [M] and [I] are maintained. The semicontinuous technique facilitates satisfactory reactor control, while with the conventional batch technique reactor control is difficult, (i.e., heat jump on BC13 introduction) which is a major reason for broad or multimodal molecular weight distributions. Evidently the semicontinuous technique is a superior... 

Adsorption measurements were made by batch technique at room temperature (25 3°C). Known amounts of tannin resin were placed in 250 mL erlenmeyer flasks containing 100 mL of metal ion solution of known concentration and were stirred for a given time period. The solutions were then filtered, centrifuged and the concentrations of metal ions were measured by AAS. The difference in the metal ion (Pb + and Ztf+) content before and after adsorption represented the amount of Pb and Zn adsorbed by new resin. 

As stated earlier, the SP trend in the pharmaceutical analysis of solid dosage forms is dominated by manual batch techniques such as grinding, sonication, dilution in volumetric flask and filtration. The unique SP requirements for solid dosages in grinding and handling large volumetries are particularly difficult to automate. 

Each point-by-point experiment requires a complete set of mixing, separation, sampling, and analysis. This usually leads to scattered results, though it may not be critical, if the D values cover a limited range from 0.1-10. However, the more the D values deviate from 1, the more accurate must be the measurements also the number of points required for a reliable extraction curve usually increases. To reduce the uncertainty and labor involved with the batch technique, the stirred cell technique has become popular. 

Two approaches are considered the batch technique and the column technique. In the former, the stationary phase (medium) is dumped into the sample in a Hquid form, usually in an aqueous environment. The stationary phase is allowed to contact the sample for a period of time and then is removed by filtration or by pouring off the liquid phase, leaving behind the compound of interest sorbed onto the stationary phase or contained in the liquid phase. The batch technique is slower than the column approach, but it is very easy to perform. 

Special attention should be paid to proper batching technique and maintenance of fins in the mixers to assure formation of a proper air-void system. 

Lounaci, M., Rigolef P., CasquiUas, G. V., Huang, H. W., and Chen, Y. 2006. Toward a comparative smdy of protein crystallization in microfluidic chambers using vapor diffusion and batch techniques. Microelect. Eng. 83 1673-76. 

Batch Technique. As with river reaeration measurements, tracers can also be put into lakes, estuaries, and oceans to measure the influence of wind on liquid film coefficient. If we have a volatile tracer in a lake with a well-established mixed layer, for example, we can apply the same batch reactor equation from Section 6.A, as though we had a well-mixed tank ... 

The enzyme recLBADH is the first catalyst that has been found to allow the highly regio- and enantioselective synthesis of 5-hydroxy-P-keto esters by reduction of the respective diketo esters. This enzymatic reaction is of enormous preparative value. The substrates are readily available by acylation of P-keto ester bisenolates and the reaction only requires a simple batch technique which is easy to scale up. Reduction of the chlorinated compound la has been performed routinely on a 75 g scale in our laboratory (8 L fed batch), yielding (S)-2a in an isolated yield of 84% [10]. 

Templeton, L. L. Grady, C. P. L., Jr (1988). Effect of culture history on the determination of biodegradation kinetics by batch and fed-batch techniques. Journal Water Pollution Control Federation, 60, 651-8. 

Chromatographic Techniques. These techniques have long been applied to the problems of separation and analysis of trace atmospheric species. For stable species, batch samples are usually collected as described in the preceding section and transported to the laboratory for subsequent analysis. However, some compounds are not sufficiently stable to survive transport intact. In situ chromatographic analyses have been used for these samples. Usually, chromatography is used on aircraft in a batch mode samples are collected, preconcentrated, and separated on a column, and the individual species are detected as they elute the process is then repeated for the next sample. Thus, as with other batch techniques, time resolution is limited. 

When the volume of crude sample is very large (or larger than can be reasonably handled with available pumps or columns), batch techniques can be used at the capture stage. In batch adsorption of the target protein by ion ex-... 

Su, P.-H. 1994. Sorption studies of atrazine using continuous stirred-flow and batch techniques. Master s thesis. Utah State University, Logan, UT. 

In summary, an efficient synthesis of nucleotide sugars could be achieved by using the repetitive batch technique. The estimated costs for enzymes and chemicals can be reduced by a factor of between 4 and 8 for the synthesis of 1 g of activated glucose [272],... 

We also combined further the enzymatic synthesis of dUDP from dUMP by NMPK with SuSy and dTDP-Glc 4,6 dehydratase (Fig. 24) [272], Using again the repetitive batch technique for enzymatic synthesis, 120 mg dUDP-6-deoxy-4-ketoglucose was obtained after product isolation (49% overall yield). 

Another impediment to studying kinetic processes in soils in the early days and even now is methodology-related (Chapter 3). With traditional batch techniques, where centrifugation is employed to obtain a clarified supernatant, reaction rates less than 5 min cannot be observed. We now know that many reactions on soils and sediments are exceedingly rapid, occurring on millisecond and even microsecond time scales. 

Advantages and Disadvantages 41 Specific Batch Techniques 42 Data Analysis 46 Flow and Stirred-Flow Methods 46 Advantages and Disadvantages 46 Continuous Flow Method 48 Fluidized Bed Reactors 50 Stirred-Flow Technique 51... 

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