Smoothness paper testing

The idea in these papers67,223,224 was to identify the potential of the capacitance minimum in dilute electrolyte solutions with the actual value of Ea=o (i.e., <7ge0m( min) = Ofor the whole surface) and to obtain the value of R as the inverse slope of the Parsons-Zobel plot at min.72 Extrapolation of Cwom vs- to Cgg0m = 0 provides the inner-layer capacitance in the / C geom, and not C ea as assumed in several papers.67,68,223,224 In the absence of ion-specific adsorption and for ideally smooth surfaces, these plots are expected to be linear with unit slope. However, data for Hg and single-crystal face electrodes have shown that the test is somewhat more complicated.63,74,219,247-249 More specifically,247,248 PZ plots for Hg/... 

The extent of bleeding in a plastic is evaluated with a test known as the sandwich method. The test sample is placed between a white, smooth surface of plasticized PVC on the top and a standardized sheet of filter paper underneath. The resulting sandwich is then placed between layers of foam material, which in turn are covered by glass plates. The resulting sandwich is allowed to remain in an exposure chamber at 50°C for 72 hours [48]. 

The choice of abradant should be made primarily to give the best correlation with service, but in practice is often chosen largely for reasons of convenience. In laboratory tests the most common are abrasive wheels (vitreous or resilient), abrasive papers or cloth and metal knives . The usual abrasive wheels and papers really only relate to situations where cutting abrasion predominates. Where plastics are used in some form of bearing the conditions will involve much smoother surfaces and materials such as smooth metal plates would be more appropriate. A problem with smooth materials is that they abrade relatively slowly and, if conditions are accelerated, give rise to excessive heat build up. 

Materials Required Arsenic limit test apparatus HgCl2—paper smooth white filter paper (having thickness in mm of 400 paper = weight in g per Sq. M.), soaked in a saturated solution of HgCl2, pressed to get rid of excess of soln. and dried at about 60°C in the dark lead acetate solution 10.0% w/v soln. of PbAc2 in C02 free water KI (AsT), 1.0 g Zn (AsT) 10.0 g Dilute Arsenic solution (AST) Standard stains, Test Solutions—are prepared according to the Indian Pharmacopoeia 1996. 

Only a constant strain method is specified with a standard strain of 25% for rubbers up to 80 IRHD, 15% for those 80 - 89, and 10% for those over 90. The compression is made between very smooth platens which are lubricated and, hence, the compression is made with some attempt at perfect slippage. Fairly obviously, the degree of slip and the test piece shape factor can affect the measured values of set. At one time it was standard to use glass-paper between the test piece and the platens to prevent slip but this produces greater concavity of the ends after release. 

An important thermodynamic parameter in cooling tower calculations is the ratio of the thermal capacity of the water stream to that of the sir stream. This parameter is referred to as, the tower capacity factor. It is shown that when air or water efficiency, are plotted against the capacity factor test points for a given tower are found to lie on a single smooth curve. The correlation is obtained, irrespective of whether the equipment is used as a water cooler or air cooler, and irrespective of the temperature levels, temperature ranges and barometric pressures. The paper also shows that when a specified amount of heat has to be rejected into a specified air stream, optimum performance giving the lowest average water temperature is obtained when the water flow rate is chosen so that its thermal capacity is equal to the potential thermal capacity of the air stream. 13 refs, cited. 

For accuracy, it is necessary that the sieves be calibrated and, if the sieves are dedicated to a single powder, the calibration should be carried out with the powder under test. It is also necessary that the sieves be checked, on a regular basis using a calibration powder, so that worn sieves can be rejected. Normally, if a sieve analysis is plotted on log-probability paper, a smooth curve results any points lying off the curve should be viewed with suspicion. 

The inlet section of the cyclone is jacketed to allow cooling of the wall or alternatively, it can be heated to achieve substantially equal gas and wall temperatures. Temperature readings of the gas during a run are taken by a bare wire thermocouple projecting into the gas just upstream from the inlet section of the cyclone it is calibrated before the run by an aspiration thermocouple in the inlet section. Temperature of the wall is measured by a thermocouple embedded in it at the spot where the entering gas impinges, where coherent deposits typically form (2,3). The surface of the inlet section is smoothed with No. 320-grit emery paper before each test. 

In this paper, we compare modeled A, estimates from the BIOM.E3.5 model and measured A estimates from ecosystem studies. Using flask data from canopy air collections within and above 50 different forest and agricultural sites might allow us to test the modeled A, estimates more realistically since the smoothing effect of atmospheric transfer observed with the tropospheric air collections will be eliminated. Furthermore, this comparison will be used to identify major gaps in the spatial representation of our study sites and to test the hypothesis that A, estimates are related to the water use efficiency of terrestrial vegetation as postulated by Buchmann et al (1998). 

Cellulose dissolves in concentrated sulphuric acid when the solution is diluted with water and boiled, soluble carbohydrates are formed, which vary in complexity from soluble celluloses and dextrins to dextrose, the final product of hydrolysis. When unsized paper is left in contact for a moment with sulphuric acid diluted with about one-fourth its volume of water, the surface of the paper is converted into a colloidal modification of cellulose called amyloid. After washing in water and dilute ammonia the paper is found to have a smooth surface, and to have been markedly toughened by the treatment. The so-called parchment paper is prepared in this way. Amyloid is colored blue by iodine the reaction is used as a test for cellulose. 

A review of the Pummerer reaction describes much of the breadth of this work [18], but a more recent paper expanded this chemistry to form spirocycles which contain adjacent quaternary carbons [20]. While the test cases (22 to form the spirocycle 23) proceeded smoothly, the application to a more complicated structure (24), which would be closer to the ring system seen in the natural product, crassanine, demonstrated that a nearby amine would interfere with the addition of the silyl enol ether as a nucleophile. While this precludes the utility of this reaction for the crassanine alkaloids, the unusual ring formed in 25, a C-3-azetidine spirocyclic indolenine, is found in the chartelline alkaoids. 

The sheets, when thoroughly dried, are of a uniform yellowish-grey colour, and of the characteristic colloidal consistency they possess a perfectly smooth surface, and are free from internal blisters or cracks. The temperature of ignition of the finished powder should not be below 172° C., and when subjected to the heat or stability test, it is required to resist exposure to a temperature of 71° C. for thirty minutes without causing discoloration of the test paper. 

The prime factor in choosing an abradant is its relevance to service, but it also has to be available in a convenient form and, for anything but ad hoc tests, it is essential that it be reproducible. In consequence of these considerations, abrasive wheels and papers or cloths predominate where cutting by sharp asperities is to be simulated. The abrasive wheel is probably the most convenient, because of its low cost, its mechanical stability, and the ease with which it can be refaced to maintain a consistent surface. Abrasive papers and cloths are cheap and easy to use but are not so readily refaced and will deteriorate in cutting power more quickly. Although basically low in cost, both wheels and papers are a considerable c.xpense when bought as standard reference materials. Materials such as textiles or smooth metal plates are more relevant for some applications, but they abrade relatively slowly, and if conditions are accelerated they give rise to excessive heat buildup. 

---