Coefficient, testing

Phenol Coefficient Test. The first important attempt at standardizing testing methods was known as the phenol coefficient test (96). It has been modified several times, and is an official AO AC screening test recognized by EPA and PDA. The phenol coefficient test compares the activity of disinfectants to that of phenol, under specific conditions, to give a number that measures the activity of the chemical tested with respect to that of phenol, ie, the phenol coefficient. The AO AC method employs visual examination of bacterial growth in a nutrient medium. The Kelsey-Sykes test (1969) is a modified method popular in British circles. 

Some tests of the AO AC (309,310) are Hsted in Table 10. The phenol coefficient test employs three test organisms and a standard concentration of... 

Available Chlorine Test. The chlorine germicidal equivalent concentration test is a practical-type test. It is called a capacity test. Under practical conditions of use, a container of disinfectant might receive many soiled, contaminated instniments or other items to be disinfected. Eventually, the capacity of the disinfectant to serve its function would be overloaded due to reaction with the accumulated organic matter and organisms. The chlorine germicidal equivalent concentration test compares the load of a culture of bacteria that a concentration of a disinfectant will absorb and still kill bacteria, as compared to standard concentrations of sodium hypochlorite tested similarly. In the test, 10 successive additions of the test culture are added to each of 3 concentrations of the hypochlorite. One min after each addition a sample is transferred to the subculture medium and the next addition is made 1.5 min after the previous one. The disinfectant is then evaluated in a manner similar to the phenol coefficient test. For equivalence, the disinfectant must yield the same number of negative tubes as one of the chlorine standards. 

If the characteristic polynomial passes the coefficient test, we then construct the Routh array to find the necessary and sufficient conditions for stability. This is one of the few classical techniques that we do not emphasize and the general formula is omitted. The array construction up to a fourth order polynomial is used to illustrate the concept. 

In the case of a second order system, the first column of the Routh array reduces to simply the coefficients of the polynomial. The coefficient test is sufficient in this case. Or we can say that both the coefficient test and the Routh array provide the same result. 

Vaccine against tetanus Vaccine against diphtheria Kelsey-Sykes disinfectant capacity test Preservative limit test Vaccine against Hib infections Dextran production Vaccine against meningitis C Alginate production Kelsey-Sykes disinfectant capacity test Kelsey-Sykes disinfectant capacity test Chick Martin/RideaI Walker disinfectant coefficient test Kelsey-Sykes disinfectant capacity test Preservative limit test... 

Phenol coefficient tests were developed in the early 20th century when typhoid fever was a significant public health problem and phenolics were used to disinfect contaminated utensils and other inanimate objects. Details of such tests can be found in earlier editions of this book. However, as non-phenolic disinfectants became more widely available, tests that more closely paralleled the conditions under which disinfectants were being used (e.g. blood spills) and which included a more diverse range of microbial types (e.g. viruses, bacteria, fungi, protozoa) were developed. Evaluation of a disinfectant s efficacy was based on its ability to kill microbes, i.e. its cidal activity, under environmental conditions mimicking as closely as possible real life situations. As an essential component of each test was a final viability assay, removal or neutralization of any residual disinfectant became a significant consideration. 

Around 1970, Kelsey, Sykes and Maurer developed the so-called capacity-use dilution test which measured the ability of a disinfectant at an appropriate in-use concentration to kill successive additions of a bacterial culture. Results were reported simply as pass or fail and not a numerical cipher (coefficient). Tests employed disinfectants diluted in clean hard water and in water containing organic material ( dirty conditions), with the final recovery broth containing 3% Tween 80 as a neutralizer. Such tests were applicable for use with a wide variety of disinfectants (see Kelsey Maurer, 1974). 

The partial correlation coefficient testing can be accomplished via the standard six-step method. Let us hold Xi constant and measure the contribution of X2, the humidity, as presented in Example 4.1 (Table 4.5 and Table 4.6). 

The goal of this section is to introduce common statistic tests used in chemical education research (correlation coefficients, /-tests, ANOVAs and ANCOVAs, tests of proportions, and some non-parametric tests), and describe specific examples of studies from the chemical education literature that have used these tests. The list of statistics tests described here is not intended to be exhaustive it simply reflects the statistical tests most commonly used by chemical education researchers. 

Grooming is highly correlated with aggressive behavior (r =0.74, p<0.01, Spearman rank correlation coefficient test the degree of aggressive behavior was determined by the amount of attacks and bites performed by the pair). 

Material contact Average (or range) friction coefficient Testing apparatus Tribological conditions References... 

Pin on disc tester Wear and friction coefficient test... 

This chapter first provides an introduction to the acoustic properties of textiles, which include propagation, absorption, and scattering of sound. The properties can be characterized by various parameters such as flow resistance, transmission loss, absorption coefficient, and scattering coefficient. Test and evaluation methods for obtaining these parameters are discussed. Based on the acoustic properties of the textiles, acoustics designers can make use of textiles in buildings and office environments to optimize sound quaUty depending on particular requirements. 

Testing Disinfectants (Phenol Coefficient Tests). The tests employed for determining the efficacy of all of the coal tar disinfectants include the Rideal-Walker test, the Chick-Martin test, the United States Food and Drug Administration (F.D.A.) method and the United States Association of Official Agricultural Chemists (A.O.A.C.) method, in which the antibacterial activity of the disinfectant is expressed in terms of its action relative to that of phenol. Each of these tests has much in common, and their main features are set out in the table below. It is necessary to follow precisely the directions as laid down in the approved method in order to get reproducible results. Each test wdll give a different coefficient... 

In addition to the phenol coefficient tests, a Use-Dilution Confirmation test has been introduced in the United States.The purpose of this test is to confirm that the recommended use-dilution of the disinfectant (calculated from the phenol coefficient of the fluid to be equivalent to that of a 5 per cent phenol solution) is in fact satisfactory. If the response in the test is not satisfactory, then an adjustment must be made to the dilutions recommended for use. 

Other Cresol-type Disinfectants and Antiseptics. Various non-irritant germicides of low toxicity, and therefore particularly suitable for disinfecting the skin and for application to wounds, contain different amounts of chloroxylenol, dichloroxylenol, benzyl cresols, o-phenylphenol, chloro-benzylphenols, special narrow-range boiling fractions of coal tar distillates, etc. They are usually dissolved in a soap, such as castor oil soap, and essential oil solution as they are only sparingly soluble in water. The various phenol coefficient tests, and particularly the Chick-Martin test, are of value in standardising such preparations, but they are of little value in determining their practical efficacy as antiseptics. For such purposes, other more specific tests are required which are beyond the scope of this book. 

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