The E-Test

In analysis of variance, the variance due to each source of variation is systematically isolated. A test of significance, the E-test, is then applied to establish roughly how seriously one must regard each source of variation. The interested reader is urged to consult books on statistics14 for discussions of this valuable statistical method. 

However, as with the E-test, its use in the clinical microbiology laboratory has been limited because of the high costs of the testing apparatus and costs of operation as compared with more traditional methods. 

Antimicrobial resistance of major consequence may be detected, e.g., the test is very useful in detecting glycopeptide-resistant enterococci and glycopeptide-intermediate Staphylococcus aureus and slow-growing pathogens such as Mycobacterium tuberculosis. Furthermore, it can be used for detecting extended spectrum P-lactamases. In conclusion, the E-test is a simple, accurate and reliable method to determine the MIC for a wide spectrum of infectious agents [33, 34]. 

The ability to detect ESBLs has clinical relevance because it will have an impact on antibiotic therapy. Producers of ESBLs are suspected when susceptibility testing indicates resistance to ceftazidime (but may be paradoxically susceptible to ceftriaxone and cefotaxime by the minimal inhibitory concentration [MIC] or disc diffusion) and susceptible to the cephamycins (11). More recently, a breakpoint of 2 ig/mL to cefpodoxime has been suggested as a standard. Another method of detection is the use of the E-test strip with a gradient of ceftazidime on one side and ceftazidime in combination with clavu-lanate on the other. The ESBLs are thought to be present when enhancement of inhibition is demonstrated. Table 2 highlights some of the more common resistance mechanisms for antimicrobial agents used commonly in the treatment of nosocomial pneumonia. 

Remark.- The answer no to pseudo-steady state test and yes to the < >E test is in theory impossible because, then, the reactivity must depend on time, which prohibits the success of the second test. 

Table 18.18 relating to switches of Figure 18.20a shows that the ratio of the right rate to the left rate is appreciably constant, about 4, which means that the ( )E test is satisfied therefore, there exist one or more rate-determining steps with the same space function. 

Finally, other tests to control jet fuel corrosivity towards certain metals (copper and silver) are used in aviation. The corrosion test known as the copper strip (NF M 07-015) is conducted by immersion in a thermostatic bath at 100°C, under 7 bar pressure for two hours. The coloration should not exceed level 1 (light yellow) on a scale of reference. There is also the silver strip corrosion test (IP 227) required by British specifications (e.g., Rolls Royce) in conjunction with the use of special materials. The value obtained should be less than 1 after immersion at 50°C for four hours. 

CEN TC 54 (Unfired pressure vessels) WG E (Testing and inspection) Draft for the EN Standard"... 

Gives some of the tests for acetaldehyde, but more feebly e.g., it restores the colour to SchifF s reagent, gives a yellow resin with NaOH, and responds to the nitroprusside test. With ammoniacal AgN03, it gives a silver minor only after 2 -3 minutes warming. It does not give the iodoform reaction. 

The fiimace E is now switched on, and takes about 20 minutes before the combustion tube packing has reached the required temperature. After 15 minutes, carbon dioxide is again passed for 5 minutes, and the apparatus tested as before for the appearance of micro-bubbles. If these are not at first obtained, the sweeping-out process must be continued until they do appear. Now that the combustion-tube packing is heated up to the required temperature and the apparatus filled with carbon dioxide, all air being swept out, the combustion may be started. 

It is advisable to test the potassium iodide - starch pap>er with acidified sodium nitrite solution the commercial test paper is, particularly if it has been kept for a considerable period, sometimes almost useless. The solution must contain an excess of acid at all times, i.e., it must give a blue colour on Congo rod paper. 

There are complications in applying the Hinsberg test to certain amines containing hydroxyl, nitro and carboxyl groups, e.g., p-N-methylamiiiobenzoic acid CHjNHC.HjCOOH (I 4) may behave in this test as a primary amine (soluble in alkali) so that it is essential to consider the properties of the original compound in conjunction with the results of the test. 

Feebly basic amines, e.g., the nitroanilines, generally react so slowly with benzenesulphonyl chloride that most of the acid chloride is hydrolysed by the aqueous alkali before a reasonable yield of the sulphonamide is produced indeed, o-nitroaniline gives little or no sulphonamide under the conditions of the Hinsberg test. Excellent results are obtained by carrying out the reaction in pyridine solution ... 

It is essential to apply both tests, since some symmetrically substituted ethylenic compounds (e.g., ilbene C4H5CH=CHCjHj) react slowly under tbe conditions of the bromine test. With dilute permanganate solution the double bond is readily attacked, probably through the intermediate formation of a cis diol ... 

Step 3. The neutral components. The ethereal solution (E remaining after the acid extraction of Step 2 should contain only the neutral compounds of Solubility Groups V, VI and VII (see Table XI,5). Dry it with a little anhydrous magnesium sulphate, and distil off the ether. If a residue is obtained, neutral compounds are present in the mixture. Test a portion of this with respect to its solubility in concentrated sulphuric acid if it dissolves in the acid, pour the solution slowly and cautiously into ice water and note whether any compound is recovered. Examine the main residue for homogeneity and if it is a mixture devise procedures, based for example upon differences in volatility, solubility in inert solvents, reaction with hydrolytic and other reagents, to separate the components. 

A two-tailed E-test of the following null and alternative hypotheses... 

J. B. Olson, "Design, Development and Testing of a Lightweight Bird-Proof Cockpit Enclosure for the E-111," presented at The Conference on Aerospace Transparent Materials and Enclosures, Long Beach, Calif., Apr. 24—28,1977. 

Given a series of tests with the new material, the average yield x would be compared with Po. If x < Po, the new supplier would be dismissed. If X > Po, the question would be Is it sufficiently greater in the light of its corresponding reliability, i.e., beyond a reasonable doubt If the confidence intei v for p included Po, the answer would be no, but if it did not include Po, the answer would be yes. In this simple apphcation, the formal test of hypothesis would result in the same conclusion as that derived from the confidence intei val. However, the utility of tests of hypothesis lies in their generality, whereas confidence intei vals are restricted to a few special cases. 

Investigators of tower packings normally report kcCi values measured at very low inlet-gas concentrations, so that yBM = 1, and at total pressures close to 100 kPa (1 atm). Thus, the correct rate coefficient For use in packed-tower designs involving the use of the driving force y — y /yBM is obtained by multiplying the reported k co values oy the value of pf employed in the actual test unit (e.g., 100 kPa) and not the total pressure of the system to be designed. 

When a flocculated feed is added to a filter tank, there is a definite time lag before this material reaches the surface of the filter medium. Since this lag time is not known at the time of testing, a lag time of 8 to 10 minutes should be allowed before starting the first leaf test on a flocculated shiny. Two, or perhaps three, tests can be run before the elapsed time exceeds the probable retention time in the full-scale filter tank. With knowledge of the elapsed time after flocculation and data relating to the rate of degradation, the rates obtained on the leaf test runs can be adjusted to some constant lag time consistent with the anticipated full-sc e design. 

The contact an e or adhesion tension of a binder solution with respecd to a powder can be determined from the slope of the penetration profile. Washburn tests can also be used to investigate the influence of powder preparation on penetration rates. The Bartell cell is related to the Washburn test except that adhesion tension is determined by available gas pressure which opposes penetration. [Bartell Osterhof, Ind. Eng. Chem., 19, 1277 (1927).]... 

The declared efficiency and power factor of a motor are affected by its loading. Irrespective of the load, no-load losses as well as the reactive component of the motor remain constant. The useful stator current, i.e. the phase current minus the no-load current of a normal induction motor, has a power factor as high as 0.9-0.95. But because of the magnetizing current, the p.f. of the motor does not generally exceed 0.8-0.85 at full load. Thus, at loads lower than rated, the magnetizing current remaining the same, the power factor of the motor decreases sharply. The efficiency, however, remains practically constant for up to nearly 70% of load in view of the fact that maximum efficiency occurs at a load when copper losses (f R) are equal to the no-load losses. Table 1.9 shows an approximate variation in the power factor and efficiency with the load. From the various tests conducted on different types and sizes of motors, it has been established that the... 

---