Timing Constraint

The advantage of single-pass over cross-flow filtration is that it is an easier system to operate and can be cost effective, particularly if the product to be filtered is expensive, because very tittle of the initial fluid is lost during filtration. However, because the flow pattern of the fluid is directly through the filter, filter life maybe too short for the fluid being filtered. The minimum flow rate needed downstream of the filter must also be considered, especially when there are time constraints to the process. In some situations it may be more advantageous to use a cross-flow system where higher flow rates may be easier to obtain. [Pg.143]

Time constraints ate an important factor in selecting nmr experiments. There are four parameters that affect the amount of instmment time requited for an experiment, A preparation delay of 1—3 times should be used. Too short a delay results in artifacts showing up in the 2-D spectmm whereas too long a delay wastes instmment time. The number of evolution times can be adjusted. This affects the F resolution. The acquisition time or number of data points in can be adjusted. This affects resolution in F. EinaHy, the number of scans per EID can be altered. This determines the SNR for the 2-D matrix. In general, a lower SNR is acceptable for 2-D than for 1-D studies. [Pg.408]

Paint-base phosphate coatings could be appHed in two to five minutes. In 1934, this time constraint was shortened even further when phosphate solutions were sprayed onto the metal surface. Processing times as short as 60 seconds became possible. [Pg.222]

Electrochemical cells may be used in either active or passive modes, depending on whether or not a signal, typically a current or voltage, must be actively appHed to the cell in order to evoke an analytically usehil response. Electroanalytical techniques have also been divided into two broad categories, static and dynamic, depending on whether or not current dows in the external circuit (1). In the static case, the system is assumed to be at equilibrium. The term dynamic indicates that the system has been disturbed and is not at equilibrium when the measurement is made. These definitions are often inappropriate because active measurements can be made that hardly disturb the system and passive measurements can be made on systems that are far from equilibrium. The terms static and dynamic also imply some sort of artificial time constraints on the measurement. Active and passive are terms that nonelectrochemists seem to understand more readily than static and dynamic. [Pg.49]

The closer one is to the failure, the more its direct effects are apparent. The cumulative effects of failure are often overlooked in the rush to fix the immediate problem. Too often, the cause of failure is ignored or forgotten because of time constraints or indifference. The failure or corrosion is considered just a cost of doing business. Inevitably, such problems become chronic associated costs, tribulations, and delays become ingrained. Problems persist until cost or concern overwhelm corporate inertia. A temporary solution is no longer acceptable the correct solution is to identify and eliminate the failure. Preventative costs are almost always a small fraction of those associated with neglect. [Pg.462]

Much of the information regarding application capabilities has been taken directly from vendor sales literature or third party reviews. The information recounted has not been extensively verified or validated due to time constraints. [Pg.280]

Element 4.13 of ISO 9001 deals with specific nonconformities and element 4.14 deals with the action to eliminate their cause and prevent their recurrence. This additional ISO/TS 16949 requirement does seem to duplicate what is covered in clause 4.14.2. However, it does add a significant aspect - a reduction plan. One could be complying with elements 4.13 and 4.14 of ISO 9001 but have no reduction plan, since element 4.14 does not impose any time constraints on corrective action or require the incidence of nonconformity to be reduced. It is quite possible to take corrective action continuously and still not reduce the number of nonconformities. The requirement may be in the wrong place (i.e. in 4.13 rather than 4.14) but it is a useful addition nonetheless. [Pg.439]

Procedures will contain many provisions, not all of which may be susceptible to verification at the time of the audit. This may be due either to time constraints or to work for which the provisions apply not being scheduled. It is therefore necessary to record which aspects have or have not been audited and engineer the program so that over a one to three year cycle all procedures and all requirements are audited in all areas at least once. [Pg.511]

The chemical process environment which refers to the complexity and novelty of the process events, their perceived danger, and the imposed time constraints on the workers... [Pg.108]

Availability of Materials. Availability of the candidate material is a very essential consideration in the decision-making process. There is no sense in specifying the use of a particular material if it cannot be obtained within the time constraints of the project. It is also advisable to select materials that are available from more than one supplier. If proprietary materials that are only available from one supplier are used, one can become a captive customer at the mercy of the supplier on cost and delivery. [Pg.1324]

NOTE Sometimes it is difficult to inspect generating tubes because of baffling. Time constraints may mean that the baffles are not always removed, although wherever possible at least some of the baffling should be removed. Unfortunately, however, bends generally restrict visual inspections to only a few feet of internal surface, which is why optical devices are popular for inspecting critical areas of large boilers. [Pg.619]

Based upon theoretical considerations of the mechanisms of hypothermic-induced cellular injury, we developed the University of Wisconsin organ preservation solution (UW solution) that has had a widespread and dramatic effect on organ preservation (Table 2). Prior to the development of this solution, the liver and pancreas could be preserved for only four to six hours. Thus, there was a large time constraint on liver and pancreas transplantation and many cadaveric organs were wasted. However, the UW solution increased preservation duration to 48 to 72 hours, and dramatically increased the quality and numbers of these organs transplanted. Furthermore, this solution appears effective for the preservation of the kidney for three days and the heart for at least 15 hours. [Pg.393]

Second, students should be provided with opportunities to perform the chemical reactions themselves and discuss with their peers the observed changes in terms of the particles and chemical and ionic equations involved. When faced with time constraints, teachers could demonstrate some of the reactions and then provide opportunities for small group discussions. [Pg.166]

Improve the control strategy for the product transition in Example 14.7. Ignore mixing time constraints, flow rate limitations on the addition of component C, and any constraints on the allowable value for The concentration of Q can exceed its steady-state value of 8mol/m but must not be allowed to go outside the upper specification limit of 9mol/m. ... [Pg.536]

Single-product campaigns. When solving Eqn. 7.4-31 the following time constraint must be taken into account for overlapping operation ... [Pg.486]

Volpe AM, Hammond PE (1991) U- °Th- Ra disequilibria in young Mount St. Helens rocks Time constraint for magma formation and crystallization. Earth Planet Sci Lett 107 475-486 Volpe AM, Goldstein SJ (1993) Ra- °Th disequilibrium in axial and off-axis mid-ocean ridge basalts. Geochim Cosmochim Acta 57 1233-1241... [Pg.174]

In TLC the detection process is static (sepaurations achieved in space rather than time) and free from time constraints, or from interference by the mobile phase, which is removed between the development and detection process. Freedom from time constraints permits the utilization of any variety of techniques to enhance detection sensitivity, which if the methods are nondestructive, nay be applied sequentially. Thus, the detection process in TLC is nore flexible and variable than for HPLC. For optical detection the minimum detectable quantities are similar for both technlqpies with, perhaps, a slight advantage for HPLC. Direct comparisons are difficult because of the differences in detection variables and how these are optimized. Detection in TLC, however, is generally limited to optical detection without the equivalent of refractive... [Pg.842]

An important difference between the statistical mixture design techniques popular in HPLC and the PRISMA model is that the former yields a computed optimum solvent composition id>ile the latter relies on a structured trial and error approach, which is readily adaptable to TLC. Solvent changes and re-equilibration in HPLC can be quite time consuming, so that it becomes attractive to ainimize the number of experiments, while for TLC, experiments can be performed in parallel and time constraints are less significant. Changes in solvent strength are also more rapidly adjusted empirically within the PRISMA model when theoretical considerations are found inadequate or require modification due to differences in the experimental approach. [Pg.866]

The best method or the most suitable combination of methods can be discussed only in regard to the actual analytical problem. The ideal method for polymer analysis in an industrial environment is often essentially that practical one which identifies and quantitates the desired components at the lowest acceptable total cost for the customer, compatible with the desired accuracy and time constraints. Three examples may illustrate the necessary pragmatic trade-off. Despite being old methods, classical polymer/additive analysis techniques, based on initial additive separation from the polymer matrix through solvent extraction methods followed by preconcentration, still enjoy great popularity. This... [Pg.744]

Justifications for the use of nonstandard (i.e., nonpreferred or nonpharmacopeial) methods of sterilization may include the heat instability of the active ingredient or an essential excipient. The choice of a method based on filtration through a microbial retentive filter and/or aseptic assembly should be justified, and the appropriate in process controls (including bioburden controls on active ingredients, excipients, bulk solutions, process time constraints etc) discussed in detail in the application. Commercial considerations should not form part of the argument for the application of a nonstandard sterilization process. The highest possible sterility assurance level should be achieved. [Pg.660]

The last part will consist in the description of a chess game in the real conditions of a tournament with time constraints, influences of the spectators in the audience and possible poisoning of the actors. This is the so-called operando approach for which many technical improvements have been made to obtain the maximum of information. Detailed examples will be given concerning the developments allowing to hunt intermediates with very short lifetimes. [Pg.101]

Another important feature of this reaction is the low pressure at which the reaction proceeds. Unlike hexamethylenediamine or other amines produced with this process, the hydrogenation of DMAPN to DMAPA proceeds at veiy low pressures. High catalyst activity and high selectivity are obtained at 100 psig for NaOH, KOH, RbOH and blended NaOH/KOH. Testing with CsOH and LiOH was only conducted at 500 psig, and these tests were not repeated at 100 PSIG for CsOH and LiOH due to time constraints. [Pg.26]

In batch operations, there is also a time constraints to be satisfied, in addition to the concentration constraints. This particular feature renders batch operations more challenging than their continuous counterparts. As shown in Fig. 4.4, even if the concentration constraints is obeyed, water from process A cannot be readily reused in process B if process A commences after process B. This constraints could be... [Pg.80]

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