The Candidate

Repellents on Skin. The candidate chemical is dissolved ia ethanol and spread over one forearm of the human subject, as DEET (1) is similarly appHed to the other forearm. Each arm is then exposed to 1500 avidM. aegppti female mosquitoes for 3 min at 30-min iatervals. Effectiveness is based on complete protection, ie, the time until the first confirmed bite (one bite followed by another within 30 min). 

A listing of compounds evaluated in the laboratory as cockroach repeUents summarizes 872 synthetic compounds out of 901 bioassayed from 1953 to 1974 (43). EenchoHc acid [512-77-6] (3-isopropyl-1-methylcyclopentanecarboxyHc acid) has been used as a standard repeUent in tests conducted by placing 20 cockroaches in a glass crystallizing dish without food and water and offering them a choice of two cardboard shelters, one of which was treated with 1 or 2 mL of a 1% solution of the candidate in acetone. Counts were made daily for seven days. 

An important part of planning an experimental program is the identification of the variables that affect the response and deciding what to do about them. The decision as to how to deal with each of the candidate variables can be made jointiy by the experimenter and the statistician. However, identifying the variables is the experimenter s responsibiUty. Controllable or independent variables in a statistical experiment can be dealt with in four different ways. The assignment of a particular variable to a category often involves a trade-off among information, cost, and time. 

Sufficient conditions are that any local move away from the optimal point ti gives rise to an increase in the objective function. Expand F in a Taylor series locally around the candidate point ti up to second-order terms ... 

Example 2-1 is just a start for preparing the final technology package to be included with the contract but it provides enough information for a client to identify the special needs required of the candidate tollers. It may need to be modified to meet the specific needs of your situation. 

In large companies that contract tolls (those with several business groups), inquiring within the company may turn up candidate tollers of which one business group was unaware. This can often aid in evaluating the candidates if good performance data is available as described in the previous section. 

The first step in assessing the candidate tollers is to notify the candidates they are being considered for this toll, and determine their interest in further evaluation. Pending mutual interest in further consideration, the companies must establish lines of communication with commercial representatives, technical/manufacturing representatives, and health, safety and environmental (HS E) representatives. There may be one person in a candidate company that funnels the communication from these three groups or several, especially if the HS E function is split. Tollers should recognize these discrete needs and be prepared to respond accurately and efficiently to enhance their merited consideration. 

Assessment questionnaires may not typically require details about technical expertise the candidate tollers may possess. It is assumed that the list of candidates who will receive the questionnaire have... 

It may be appropriate to request that candidate tollers provide contacts at previous client facilities to allow general inquiries about their performance. This allows a company seeking a toller to determine whether the safety, environmental and quality programs are truly implemented as written. In addition, it can reveal whether the candidates made good faith efforts to meet contractual obligations. 

The candidate tollers security policy should emphasize the importance of protecting people, property and the operational practices against loss by intentional destruction or theft. During the site visit, check to see if appropriate methods are taken to control entiy and movement of people and vehicles as a security measure. One telltale sign is that you may be denied access to an area because of another company s confidential process. Though an interference, it affirms a sound security practice. Determine whether security inspections are being held during off-duty hours. 

Some of the candidate tollers practices, records and documents can not be assessed using only a questionnaire form. A site visit to one or more of the short-listed candidate tollers is usually indicated. This is especially helpful if an unfamiliar toller is competing against a toller that is currently being used. Candidate tollers can use the information in this section to prepare for a site interview when one is requested. 

The company seeking to toll internationally in this case will benefit from selecting an experienced team of reviewers with international experience. Tollers seeking business from foreign companies would benefit by recognizing these new aspects may present difficulties when their capabilities are being assessed. The candidate tollers could prepare information in advance that helps respond to these potential concerns. 

If a standard form was used in the qualification phase, a system should exist to rank the respondents that are being considered. Such a system can be as simple as the reviewers making a written recommendation summarizing the strong points of their selections. Some companies have developed forms that allow the final scores to be quantified. Appendix C, Sample Toller Assessment—Qjiantitative Format contains such an example. With either method, the client should consider having two or more reviewers discuss the candidates and agree on the recommended finalists. 

Each company seeking tollers has its own approach to how they bid toll contracts. In some cases, the candidate tollers have been ranked... 

The technical review team should compare the thoroughness of each scope of work related response between the candidate toller proposals. 

The two teams should meet, compare rankings and select the candidate with the best overall ranking. 

I will be using a surface mount tantalum capacitor because they typically exhibit about 50 percent of the ESR of electrolytic capacitors. I will also derate the rating of the candidate capacitors by 30 percent at -i-85°C ambient temperature. 

There are very few surface mount capacitors with the desired value, voltage rating, and low ESR all in one part. It would be more conservative to parallel two capacitors of no less than one-half the desired capacitance value. This allows many more second sourced capacitors to be used and lowers the ESR. Lets use two 330 pF, 10 V tantalum capacitors in parallel. The Candidates now become ... 

Capacitors at the higher voltages have smaller capacitance values. There will be two 68 pF capacitors in parallel. The candidates are ... 

In summary, it is evident that the only moderators of merit are based on elements of low atomic weight. Practically, this limits the choice to elements of atomic number less than sixteen. Gases are of little use as moderators because of their low density, but can be used effectively in chemical compounds such as HjO and DjO. The choice of potential moderators of practical use thus rapidly reduces to the four materials shown in Table 3. Comparing the candidate moderators in Table 3 with our requirements listed above we may note ... 

Nine years later, the Zeitschrift fur physikalische Chemie was followed by the Journal of Physical Chemistry, founded in the USA by Wilder Bancroft (1867-1953), one of Ostwald s American students. The chequered career of this journal is instructively analysed by both Laidler (1993) and Servos (1990). Bancroft (who spent more than half a century at Cornell University) seems to have been a difficult man, with an eccentric sense of humour thus at a Ph.D. oral examination he asked the candidate What in water puts out fires , and after rejecting some of the answers the student gave with increasing desperation, Bancroft revealed that the right answer was a fireboat . Any scientific author will recognize that this is not the ideal way for a journal editor to behave, let alone an examiner. There is no space here to go into the vagaries of Bancroft s personality (Laidler can be consulted about this), but... 

Once the candidate corrective measure alternatives have been identified, a more detailed evaluation of each alternative needs to be undertaken. From an engineering perspective, the first step in the evaluation process would include the development of a conceptual design for each alternative. The conceptual design would consist of a process description, a process flow diagram and a layout drawing. Preliminary sizing of equipment and utility and land requirements would be developed. In addition, chemical requirements and residuals produced can be estimated. From the conceptual design, permitability and residuals disposal issues can be identified and addressed. 

If in the service of a component it is the deflection, or stiffness, which is the limiting factor rather than strength, then it is necessary to look for a different desirability factor in the candidate materials. Consider the beam sim-ation described above. This time, irrespective of the loading, the deflection, S,... 

The candidate lean streams can be classified into Nsp process MSAs and Nse external MSAs (where Nsp + Nse — Ns). The process MSAs already exist on plant site and can be used for the removal of the undesirable species at a very low cost (virtually free). The flowrate of each process MSA that can be used for mass exchange is bounded by its availability in the plant, i.e.,... 

Toluene is to be removed from a wastewater stream. The flowrate of the waste stream is 10 kg/s and its inlet composition of toluene is 5(X) ppmw. It is desired to reduced the toluene composition in water to 20 ppmw. Three external MSAs are considered air (S2) for stripping, activated carbon (S2) for adsorption, and a solvent extractant (S3). The data for the candidate MSAs are given in Table 3.6. The equilibrium data for the transfer of the pollutant from the waste stream to the yth MSA is given by... 

To reduce cresol content in discharged wastewater sOeams, four MSAs are avaiiaUe two MS As to remove cresol from gaseous stress and two MSAs to remove cresol from liquid streams. Tables 7.4. and 7.5. provide data for the candidate MSAs. 

A process lean stream and an external MSA are considered for removing H2S. The process lean stream, S1, is a caustic soda solution which can be used as a solvent for the reactive separation of H2S. An added bonus for using the process MSA is the conversion of a portion of the absorbed H2S into Na2S, which is needed for white-liquor makeup. In other words, H2S pollutant is converted into a valuable chemical which is needed in the process. The external MSA, S2, is a polym ic adsorbent. The data for the candidate MSAs are given in Table 8.2. The equilibrium... 

The next step is to screen the candidate refrigerants with the objective of minimizing the utility cost. This step can be accomplished by examining the cost of... 

One important feature in some of the new examination regulations is the recognition of the candidate s signed record of laboratory work. We are, in fact, beginning to discover an inherent. defect in practical chemistry as an examination subject, namely, its resistance to compression into a compact and convenient examination form. 

Compare the candidates for minimum reflux ratio. The candidate having the largest (maximum) numerical value is the minimum reflux ratio for the column. 

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