Mixed-sequence

Sodium dithionite solution can be produced on-site utilizing a mixed sodium borohydride—sodium hydroxide solution to reduce sodium bisulfite. This process has developed, in part, because of the availabiHty of low cost sulfur dioxide or bisulfite at some paper mills. Improved yields, above 90% dithionite based on borohydride, can be obtained by the use of a specific mixing sequence and an optimized pH profile (360,361). Electrochemical technology is also being offered for on-site production of sodium hydrosulfite solution (362). 

PNA targeting of duplex DNA is not limited to homopurine sequences. Under special circumstances (high negative superhelical stress) mixed purine-pyrimidine PNA-peptide conjugates can bind by duplex invasion (Fig. 4.7) [31], but such complexes are of limited stability. However, using a set of pseudo-complementary PNAs containing diaminopurine-thiouracil substitutions, very stable double duplex invasion complexes can be formed (Fig. 4.4) and the only sequence requirement is about 50% AT content. Very recently, it was also demonstrated that reasonably stable helix invasion complexes can be obtained with tail-clamp PNA comprising a short (>six bases) homopyrimidine bis-PNA clamp and a mixed sequence tail extension [32] (Fig. 4.7). 

Goronszy, M.C., Rigel, D. Simplified biological phosphorus removal in a fed-batch reactor without anoxic mixing sequences. J. W P C F 63 (3), 1991, 248-258. 

Fig. 11.6 Pulse sequence for two-dimensional homonuclear chemical-shift correlation experiments. The gray box indicates the mixing sequence, with some examples shown in more detail a RFDR, b RIL, c C7, d DRAWS, e DREAM.

Every NMR experiment must have a preparation sequence (inducing the nuclei to resonate) and detection capability (finding out what happened). Two-dimensional NMR spectroscopy adds two more domains between preparation and detection. These are an indirect evolution time, q, and a mixing sequence (see Figure 3.15). The two dimensions of two-dimensional NMR spectroscopy are those of time. In one time domain, FIDs containing frequency and intensity information about the observed nuclei is collected. The second time dimension refers to the time that elapses between some perturbation of the system and the onset of data collection in the time domain. The second time period is varied, and a series of FID responses are collected for each of the variations. 

During the mixing of concrete, the folding action of the mixing sequence causes air voids to be formed in the system, which in normal concrete would be reduced by the mechanical forces used in placing the concrete, leaving... 

Fig. 5a-d AFM images of DNA assembled in various devices, a Mixed-sequence DNA between platinum electrodes spaced by 40 nm. Scale bar 50 nm. b Height image of poly(dG)-poly(dC) DNA bundles on platinum electrodes. The distance between electrodes is 200 nm, and the scale bar is 1 um. c High magnification image of the device shown in b. Several DNA bundles clearly extend over the two electrodes. Scale bar 200 nm. d Poly(dG)-poly(dC) DNA bundles on platinum electrodes fabricated on a mica substrate. Scale bar 500 nm. For all these devices, no conduction was observed (from [59], with permission Copyright 2001 by the American Institute of Physics)... 

The mixing sequence given above is necessary for maintaining maximum chlorine stability. 

Normal mixing sequence Mixing sequence for unpreserved products... 

The manufacturer s instructions should be carefully followed when using admixtures. Specific effects produced in concrete by admixtures are dependent on the instructions provided by the manufacturer of the admixture and a number of factors such as cement composition, aggregate characteristics, the presence of other admixtures and ambient conditions. The interaction of the selected admixture with these factors and the extent of the side effects should be verified prior to field use. The desired effect should not be too sensitive to small variations in the amount of admixture used, or in the amounts of other concrete constituents used. Since the effects produced may vary with the point of addition in the mixing cycle, a standard mixing sequence should be established and admixtures must not be added during transportation, placing or compaction. Admixtures of all classes may be available in either powder or liquid form and since relatively small quantities are used, it is important that suitable and accurately adjusted dispensing equipment be employed. All liquids, particularly emulsion types, should be protected from exposure to drastic temperatures. 

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