Read-across

To convert percent absorption (% A) to absorbance, find the present absorption to the nearest whole digit in the left-hand column read across to the column located under the tenth of a percent desired, and read the value of absorbance. The value of absorbance corresponding to 26.8% absorption is thus 0.1355. 

Step 2. Go to the left-hand column in table, final Suction Pressure (hs). Read across to find evacuation time equal to or less than that determined in Step 1. Read to the top of table and note unit number. See Table 6-15. 

E. Referring to Figure 9-21B or 21C, read up from the abscissa to the pressure drop line selected, and read across to the ordinate (note differences) ... 

First, for Figure 14-22, enter at the top at rpm and move to the first estimating turbine wheel diameter then read down to the TSR (calculated or from tables) at Ib/kw-hr read across to base steam rate in Ib/hp-hr. Note that the base steam rate is per hp-hr, and the TSR is per kwh (or kw-hr). Now correct the base steam rate for the horsepower loss (i.e., the portion of blades of turbine spinning outside the nozzle arc, creating friction and windage). From Figure 14-23, at the top read rpm at the exhaust pressure on curved lines noted cond, read down to the estimated wheel diameter, and read the horsepower loss on the left vertical axis. 

Other turbine wheel diameters can be explored using the same approach. The horsepower limit is established by reading across from the speed rpm and intersection of the the trial wheel diameter and by reading down to interpolate the horsepower limit. If the wheel diameter selected at your rpm is lower or greater than the required horsepower for the application, another speed and/or wheel diameter must be selected. After the horsepower loss is established, Figure... 

Measure the outside air make-up quantity, taking a pattern of readings across the area of the duct or grille ... 

Precipitation diagram. Choose the cation row and read across to the anion column. If the block is blank, no precipitate will form. If the block is colored, a precipitate will form from dilute solution. Where a formula is given, that is the only cation-anion combination in that block that will precipitate. 

Predictions based on structure-activity relationships (SARs), including qualitative and quantitative mathematical models, and the use of read-across data from related chemicals. 

There are software that use more approaches for the prediction of toxicity expert systems, QSAR, and read-across (http //www.insilico.eu/use-qsar.html). 

Enoch SJ, Cronin MTD, Madden JC, Hewitt M (2009) Formation of structural categories to allow for read-across for teratogenicity. QSAR Comb Sci 28(6-7) 696-708... 

Hewitt M, Ellison CM, Enoch SJ, Madden JC, Cronin MTD (2010) Integrating (Q)SAR models, expert systems and read-across approaches for the prediction of developmental toxicity. Reprod Toxicol 30(1) 147-160... 

Although the testing programme is largely prescriptive, there is some degree of latitude, for example studies on a specific substance depend on the chemical structure and physical form and some may be technically impossible or scientifically unnecessary. It may also be possible to predict the results for certain properties by read across to an analogue tested substance of closely similar chemical structure. 

Surrogate Data Calculation, Read-Across and SAR/QSAR... 

The properties of substances can sometimes be assessed on a case-by-case basis using the read-across approach. The properties of a substance are predicted from data on close chemical analogues with similar physicochemical properties. Similar biological properties are anticipated, since toxicokinetics, in particular... 

The Notification of New Substances scheme set out in Directive 92/32/EEC, which is designed to protect people and the environment from the possible harmful effects of new substances and to create a single market, is described. Methods for making notification easier, quicker and cheaper are considered. The determination of test requirements is discussed and the Read Across and Family Approach strategies for test reduction are outlined. 

Reading across the columns, on line 5, the plant may accumulate its solvent for as long as 180 days, or until the plant has reached a volume of 2000 kg (500 gallons 1892.5 L) in... 

When data do not exist for a given toxicological endpoint, or when data are limited, the use of SARs may be considered in the hazard assessment. The potential toxicity of a substance, for which no or limited data are available on a specific toxicological endpoint can, in some cases, be evaluated by read-across from structurally or mechanistically related substances for which experimental data exist. The read-across approach is based on the principle that structurally and/or mechanistically related substances may have similar toxicological properties. 

Based on structural similarities between different substances, the toxic potential for a specific endpoint of one substance or a group of substances can be extended (read-across) to a substance, for which there are no or limited data on this endpoint. 

Based on mechanistic similarities between different substances, a mechanism of toxicity or mode of action identified for a substance and/or group of substances and causally related to adverse effects in a target organ can be extended (read-across) to a substance for which a similar mechanism or mode of action has been identified, but where no or limited data on a specific endpoint are available. In such cases, the substance under evaluation may reasonably be expected to exhibit the same pattern of toxicity in the target organ(s) and tissue(s). 

There are no formal criteria to identify structural alerts for toxicity in general, for a specific endpoint or for read-across to closely related substances. However, for substances where no data for one or more endpoints are available, the assessment at a screening level can be performed using data obtained from closely analogous substance(s) to indicate a potential for toxicity, e.g., if a closely related substance has a potential for inducing a specific toxic effect, the substance for which no data on this specific toxic effect are available may reasonably be expected to exhibit a similar potential for inducing this specific toxic effect. In the case of such knowledge, it should be considered whether these data are adequate for a hazard assessment. 

When analog data are used to fill the data gaps for one or more endpoints, the data for the analogs must be compared and discussed in relation to the substance under evaluation in order to shed light on the similarities and differences in the Toxicological Profile of the substance under evaluation and its analog(s). If the available test results show that the substances in a category behave in a similar or predictable manner, then read-across can be used to assess the substance for which no data on a specific endpoint are available. 

It is mentioned that the TTC concept has been incorporated in the risk assessment processes in a number of regulatory schemes as a scientifically sound tool to justify waiving or generation of animal data. It is also stressed that, in contrast to approaches such as read-across or chemical categorization, the use of the TTC is not focused or limited to the identification of potential hazards but also provides a quantitative estimate of potency. 

Substances with similar properties (physical, structural, toxicological) may be grouped together to allow read across where the toxicological findings for one substance can be assumed for similar substances. Full details are outside the scope of this chapter, but as an example ionic bromides will have similar toxicity when expressed in terms of bromide ion (7). Similarly inorganic borates and boric acid have similar toxicity when expressed as boron equivalents (8) but separate toxicity assessments are required for boron-containing materials that do not hydrolyze to the borate ion. 

Roberts, D.W., Aptula, A.O., Patlewicz, G. and Pease, C. (2008) Chemical reactivity indices and mechanism-based read-across for non-animal based assessment of skin sensitisation potential. J. Appl. Toxicol.,... 

The three kinds of disease process we have surveyed in this chapter are the natural analogues of experimental probes of the brain systems that normally alter brain states in animals. Not surprisingly, they alter consciousness in informative ways in humans. Strokes are the equivalent of electrolytic and excitatory neurotoxic lesions seizures are the equivalent of direct electrical and chemical stimulation alcohol is the equivalent of parenteral drug administration. In reading across the three disease classes in search of unifying concepts, I hope to stimulate a new era of experimental work in animals, as well as to celebrate what we have accomplished in the arena of human neuropsychology. 

In the log table, find 2.0 (sometimes written as 20) in the lefthand column. Read across to the column under 3. This gives log 2.03 = 0.3075. 

Demonstrations of simulated leaks of hydrogen as compared to petroleum on automobiles are well documented. The demonstrations clearly show that a hydrogen leak is less catastrophic than a petroleum leak following ignition. However, there will be no direct read across to a complex military vehicle, such as a ship, where there could be numerous watertight bulkheads and enclosures, which could render hydrogen more hazardous under battle damage than the current navy diesel fuel. 

The equilibrium problem matrix. The information concerning components, stoichiometry and formation constants can be written in the form of a table which for the purposes of this chapter will be referred to as the equilibrium problem matrix (EPM). An example of an EPM table for the monomeric A1 species is shown in Table 5.6. The EPM is a logical and compact format for summarising all the information required for solving equilibrium problems. Reading across the rows of the table the information needed to formulate the mass action expressions is contained. Down each component column are the coefficients with which the concentration of each species should be multiplied to formulate the mass balance equation (MBE). Therefore, once given the chemical problem in an EPM format the nature of the mass action equations, formation constants and mass balances considered can all be deduced. 

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