Class III

C-atom with three single bonds (class III) 3 3... 

Certain members, particularly those in Class (iii), give coloured products with oxidising agents. 

D) No general reaction can be cited for the preparation of crystalline derivatives of Class (iii). Triphenylamine, when nitrated in acetic acid with fuming nitric acid, gives tri-/>-nitrophenylamine, m.p. 280°. The presence of substituents in the phenyl groups may however complicate or invalidate nitration. 

Compounds of class (iii) are either totally synthetic (a few steroids) or derivatives of natural products isolated from plants or microorganisms. They are discussed within the indicated sections. We will briefly describe published syntheses of the most common compounds... 

Handbook 44 defines five accuracy classes for scales in terms of the value of the scale division and the number of divisions. Class I appHes to precision laboratory weighing. Class II appHes to laboratory weighing (precious metals, gems, and grain test scales). Class III appHes to the majority of industrial and retail scales, and to all scales not specified in the other categories. Class III L appHes to vehicle, Hvestock, railway, crane, and hopper scales. Class nil appHes to portable scales used for highway weight enforcement. 

Table 1 is condensed from Handbook 44. It Hsts the number of divisions allowed for each class, eg, a Class III scale must have between 100 and 1,200 divisions. Also, for each class it Hsts the acceptance tolerances appHcable to test load ranges expressed in divisions (d) for example, for test loads from 0 to 5,000 d, a Class II scale has an acceptance tolerance of 0.5 d. The least ambiguous way to specify the accuracy for an industrial or retail scale is to specify an accuracy class and the number of divisions, eg. Class III, 5,000 divisions. It must be noted that this is not the same as 1 part in 5,000, which is another method commonly used to specify accuracy eg, a Class III 5,000 d scale is allowed a tolerance which varies from 0.5 d at zero to 2.5 d at 5,000 divisions. CaHbration curves are typically plotted as in Figure 12, which shows a typical 5,000-division Class III scale. The error tunnel (stepped lines, top and bottom) is defined by the acceptance tolerances Hsted in Table 1. The three caHbration curves belong to the same scale tested at three different temperatures. Performance must remain within the error tunnel under the combined effect of nonlinearity, hysteresis, and temperature effect on span. Other specifications, including those for temperature effect on zero, nonrepeatabiHty, shift error, and creep may be found in Handbook 44 (5). The acceptance tolerances in Table 1 apply to new or reconditioned equipment tested within 30 days of being put into service. After that, maintenance tolerances apply they ate twice the values Hsted in Table 1.

Fig. 12. Calibiation curves for a Handbook 44 Class III 5,000 d scale. See text.

Parameter Class 1 Class II Class III Class III L Class IIII... 

Most are not used in commercial transactions however, many approved models are available. Some of the precision scales fall into accuracy class III, but Class I and Class II are more typical for the balances. Handbook 44 is of limited value in describing the accuracy characteristics of these products because, for example, 1 mg is the smallest division size allowed. For this reason, only the number of displayed divisions is discussed herein. 

The class III cytokine receptor family includes two TNE receptors, the low affinity NGE receptor and 7-ceU surface recognition sites that appear to play a role in proliferation, apoptosis, and immunodeficiency. TNE-a (- 17, 000 protein) is produced by astrocytes and microglia and can induce fever, induce slow-wave sleep, reduce feeding, stimulate prostaglandin synthesis, stimulate corticotrophin-releasing factor and prolactin secretion, and reduce thyroid hormone secretion. TNE-a stimulates IL-1 release, is cytotoxic to oligodendrocytes, and reduces myelination this has been impHcated in multiple sclerosis and encephalomyelitis. Astrocyte TNE-a receptors mediate effects on IL-6 expression and augment astrocytic expression of MHC in response to other stimulants such as lEN-y. 

Each plant or laboratory should adopt definite rules and procedures for electrical iastahations and work. All iastahations should be ia accordance with the National Electrical Code (NEC) for the type of ha2ard, eg. Class I flammable gas or vapor Class II organic, metallic, or conductive dusts and Class III combustible fibers and the degree of process containment, eg. Division 1 open and Division 2 closed (67). Regardless of the flammabiUty of the materials ia the iastaHed operations, changes ia procedure involving use of such materials often occur, sometimes without concurrent alteration of the electrical iastaHation. 

Post-amendment devices ate automatically classified as Class III devices. However, a post-amendment device can be brought to market under the 510(k) process, if the PDA determines that the device is "substantially equivalent" to a preamendment device. If the post-amendment device is identical to a preamendment device, it is substantially equivalent. Then the 510(k) is accepted by the PDA and the post-amendment device is placed in the same class as the preamendment device to which it is substantially equivalent. Pot example, a wound dressing identical to a preamendment Class I wound dressing would be found substantially equivalent to the preamendment wound dressing and classified in Class I. 

Prevention of Significant Deterioration. EPA originally issued regulations for Prevention of Significant Deterioration (PSD) in December 1974 to protect clean air areas. Three air quaUty classes were designated Class I to protect pristine areas. Class II to allow moderate development, and Class III to permit more intensive development. Most areas in the United States were initially designated as Class II. Many large national parks and wildlife areas have been classified as Class I. 

Class III devices, unless they are substantially equivalent to a device already marketed without a PMA appHcation, require formal PDA approval through the PMA process before initial sale. The PMA process is comparable to the new dmg approval process (18). In both cases, safety and effectiveness data must be reviewed by PDA prior to marketing. An approved PMA appHcation acts like a private Hcense granted to the appHcant to market a particular device. Other firms seeking to market the same type of device for the same use must also have an approved PMA. 

PMA requirements differ between preamendment and post-amendment devices. Preamendment devices are those in commercial distribution before May 28, 1976 post-amendment devices are those first commercially distributed after the date. Class III post-amendment devices that are not substantially equivalent to preamendment Class III devices are considered new devices. Manufacturers of such devices are required to obtain PMA appHcation approval before marketing these. If the post-amendment device is substantially equivalent to a preamendment device and PDA has not initiated a regulatory process specifically requiring the submission of a PMA for the device category, a 510(k) submission can be made. 

Canada. Sorbic acid and potassium sorbate are cleared in Canada as Class II and Class III preservatives (Table XI, Parts II and III, Food and Dmg Regulations) (162). They are cleared for use in the same food types. As in the United States, their lawful use is predicated upon conformity with pubHshed food standards. Otherwise they may be used in bread and unstandardized foods, except meat (Divisions 14 and 21 of the regulations), fish, and poultry, at levels up to 1000 ppm, in cider and wine at 500 ppm, and in cheeses at 3000 ppm in accordance with the food standards for cheese (Section B of the regulations). 

The Class I binary diagram is the simplest case (see Fig. 6a). The P—T diagram consists of a vapor—pressure curve (soHd line) for each pure component, ending at the pure component critical point. The loci of critical points for the binary mixtures (shown by the dashed curve) are continuous from the critical point of component one, C , to the critical point of component two,Cp . Additional binary mixtures that exhibit Class I behavior are CO2—/ -hexane and CO2—benzene. More compHcated behavior exists for other classes, including the appearance of upper critical solution temperature (UCST) lines, two-phase (Hquid—Hquid) immiscihility lines, and even three-phase (Hquid—Hquid—gas) immiscihility lines. More complete discussions are available (1,4,22). Additional simple binary system examples for Class III include CO2—hexadecane and CO2—H2O Class IV, CO2—nitrobenzene Class V, ethane—/ -propanol and Class VI, H2O—/ -butanol. 

Class III Premarket Approval. Similar to a new dmg approval, a premarket approval grants the appHcant a Hcense to market a specific weU-characterized device. These devices are subject to the requirements of Section 515 of the Eood, Dmg, and Cosmetic Act. A post-amendment device is a device put ia commercial distribution after May 28, 1976. If it is not substantially equivalent to a preamendment device it is automatically ia Class 111, and a premarket approval appHcation (PMA) is required. The appHcation must iaclude reports of preclinical and clinical studies done ia support of claims of safety and efficacy as well as any labeling claims made for the device. Once the PMA is submitted, the PDA determines whether the appHcation iacludes the required information. If the PMA is suitable for scientific review, the PDA has 180 days from the filing date to approve or deny the appHcation. Polybutester, polydioxanone, polyglyconate, and ePTPE sutures are all regulated as Class 111 devices. 

Fleca.inide, Elecainide acetate, a fluorobenzamide, is a derivative of procainamide, and has been reported to be efficacious in suppressing both supraventricular and ventricular arrhythmias (26—29). The dmg is generally reserved for patients with serious and life-threatening ventricular arrhythmias. Elecainide depresses phase 0 depolarization of the action potential, slows conduction throughout the heart, and significantly prolongs repolarization (30). The latter effect indicates flecainide may possess some Class III antiarrhythmic-type properties (31). 

Pirmenol. Pirmenol hydrochloride, a pyridine methanol derivative, is a racemic mixture. It has Class lA antiarrhythmic activity, ie, depression of fast inward sodium current, phase 0 slowing, and action potential prolongation. The prolongation of refractory period may be a Class III property. This compound has shown efficacy in converting atrial arrhythmias to normal sinus rhythm (34,35). 

The Class III antiarrhythmic agents markedly prolong action potential duration and effective refractory period of cardiac tissue. The QT interval of the ECG is markedly prolonged. 

Other Glass III Antiarrhythmic Agents. Clofihum phosphate is a benzene-butanaminium derivative that has highly specific Class III antiarrhythmic activity. It is orahy active, has a rapid onset of action, and a reasonably long duration of antiarrhythmic activity. In preliminary clinical studies, clofihum has shown efficacy against spontaneous ventricular tachycardias (69). 

Regulation. Dental implants are regulated by the Food and Dmg Administration. AH dental implants faH iato the FDA class III which covers devices that are life sustaioiag, life supportiag, or are implanted iato the body and have the potential to cause unreasonable risk, illness, or iajury. Devices ia class III are requited to have appHcatioas for premarket approval (315). There are 15 to 20 companies that have FDA marketing clearance for specific dental implants, based on substantial equivalency to implants marketed prior to 1976, and approximately one third of these companies are foreign. Marketing clearance is not the same as premarket approval. 

Combustible Eiquid A term used to classify certain liquids that will burn on the basis of flash points. The National Fire Protection Association (NFPA) defines a combustible liquid as having a flash point of 100°F (37.8°C) or higher. See also, Flammable Liquid. Class II liquids have flash points at or above 100°F, but below 140°F. Class III liquids are subdivided into two subclasses. 

B) Characteristics of the arrester chosen from Table 18.9, class III Standard rating, V,... 

The data for the average decrease in metal thickness in 4 years and the linear corrosion rate are given in Table 4-2. In addition, extrapolations of the rate for 50 and 100 years are given, which are of interest for the corrosion likelihood of objects buried in earth. It can be seen from the results that film formation occurs in class I soil. In class II soils, the corrosion rate decreases with time only slightly. In class III soils, the decrease with time is still fairly insignificant. 

Class III areas are specifically designated as heavy industrial. 

Classes II and III include all tests in which the specified gas and/or the specified operating conditions cannot be met. Class II and Class III basically differ only in method of analysis of data and computation of results. The Class II test may use perfect gas laws in the calculation, while Class III must use the more complex real gas equations. An example of a Class II test might be a suction throttled air compressor. An example of a Class III test might be a CO2 loop test of a hydrocarbon compressor. Table 10-4 shows code allowable departure from specified design parameters for Class II and Class III tests. 

Ailowabie Departure From Specified Design Parameters for Class II and Class III Tests... 

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