MASS PREPARATION

Altering the grain size mostly amounts to reduction and is accompanied by changes in the grain size distribution and the specific surface. This specific surface is a major ceramic property of raw materials 

In a laboratory the distribution is determined in a sieve shaker (figure 9.2). This consists of a number of stacked sieves and a container at the bottom. The sieves are mounted on a shaking device and the shaking time and frequency can be adjusted. 

In figure 9.3 the results of table 9.2 are plotted as a histogram, i.e. the diameter of the sieve pore against the separate mass percentage. 

In figure 9.4 the grain size distribution of table 9.2 is plotted cumulatively. 

When the raw material is supplied in large fragments, these will first have to be crushed. In general hammers are used for this or the material is compressed. Two devices applied here are the conical crusher (figure 9.5) and the prall mill. 

---

The Glaze,—At Sevres the glaze is composed of the pegmatite from St, Yricx, which is felspar, incorporated with a certain proportion of quartz. Although the proportions of these two constituents may vary considerably in small pieces, this ceases to be the case in the enormous mass prepared at the same time at Sevres, as shown by the following table... 

S. Hanessian, P. Dextraze, and R. Masse, Preparative and exploratory carbohydrate chemistry. Regiospecific and asymmetric introduction of functionalized branching in carbohydrates, Carbohydr. Res. 26 264 (1973). 

The simplest way to determine the grain size distribution is with the help of the sieve tower. This method is decribed in the chapter Ceramic in general / mass preparation . 

Sometimes it is necessary to separate particles with a certain grain size distribution from the raw material components or from the total raw material mass before mass preparation or the moulding can begin. This can for instance be done with sieves, spray driers and wind sievers. In figures 9.7 and 9.8 the latter two devices are shown. 

The instructions for gelatin mass preparation direct that gelatin powder be blended with water, a plasticizer, and colorant until a uniform consistency is achieved, then heated until molten. The recommended blend time is 20 min at a temperature of 60°C + 5°. The temperature of the molten gelatin just prior to formation into a ribbon is critical too high a temperature causes the gelatin to deteriorate, and a low temperature affects flow rate. Both conditions are to be avoided for their deleterious effect on capsule formation. For these reasons,... 

In order to examine the operational conditions determined and to make the results more feasible for industrial application, and also to provide sample product for further application testing, experiments for mass-preparation are carried out under the optimal conditions determined above, following the procedure described in Section 15.2 and with commercial TiCl4 as the raw material, the composition of which is indicated in Table 15.5. 

Amount of Pb solution, Mass Preparation of gravimetric solution of Pb... 

The contact mass prepared by this technique is as a rule highly active. 

To prepare basic iron-II-oxide, the dried mixed hydrated iron oxide mass (prepared in step 1), needs to be dehydrated under suitable conditions. To do this, place the dried mass into a desiccator, filled with concentrated sulfuric acid, and then gently heat the dried mass to about 50 to 60 Celsius for 12 to 24 hours. After the heating process, the final product should be a jet-black fine mass, which can be ground into a powder if desired. The final dried product should be kept in airtight containers. 

A confection is a compound mass, prepared by uniting a medicinal substance with saccharine matter, in such manner as to preserve the virtues of the medicament, to cover its taste, or to facilitate its administration. ... 

A small-scale operation of this type was conducted during the Asian influenza threat (1957-1958). At first, it seemed like an almost insurmountable task. How to alert, inform, and protect 180,000,000 people from a disease that might occur within the next several months How to meet the many technical problems of the detection and isolation of the virus, the type and potency of a vaccine, the mass preparation of vaccine, the orderly distribution of vaccine, the adoption of priorities for vaccination The medical and health professions had to be given scientific information concerning the threat and its characteristics. The public had to be alerted and informed. Many of us working in the fields of civil defense and aware of the small public response to our best efforts looked askance at the Asian influenza challenge. Perhaps the smallness of the groups that came for instruction in civil defense in spite of best efforts chilled our ardor for the task ahead. 

H. Moissan observed that when chromous chloride is heated to 440° in hydrogen sulphide, this sulphide is formed this is also the case when chromic sulphide is heated in hydrogen. A. Moulot obtained this sulphide by heating chromium in an atm. of hydrogen sulphide in an electric furnace. The black mass prepared at a high temp, forms opaque, prismatic crystals of sp. gr. 4-08. The black, non-crystalline powder has a sp. gr. 3 97. W. F. de Jong and H. W. V. Willems found that the... 

According to Nitta the introduction of chlorides or bromides into the catalyst salt mass during the formation of deposited catalyst, promotes an increase in ee by virtue of the inerease in D, but the overall rate of the reaetion decreases under these eonditions. Additions of NiCfy NaCl, FeCfy and NaBr or of HCl or HBr to the eatalyst precursor mass prepared by method A (see Table 4.8.) increases ee from 36.1% to 49.7-57.5%, and also increases D from 13 to 20-30 nm while narrowing the size distribution of the niekel crystallites... 

The increase in ee after the addition of NiCl2 during the preparation proeess is of interest. The introduction of 29.8% of this salt into the catalyst mass prepared by methods A, B, and C (see Table 4.8.) sharply diminishes the speeific surface of the reduced metal, which indicates an increase in D. Depending on the method employed, the ee increased from 36.1% to 54.7% in... 

The main properties of alumina-supported indium oxide (hi203) catalysts with In loadings between 2 and 22 mass%, prepared by impregnation, have been... 

Batteries with active mass prepared from Initial Capacity measured/ rated> Cycle Life (Number of Cycles)... 

Mass prepared in this way is poured into a linen sack and placed in an extractor followed by elution with ethyl ether then methylene chloride. 

Protocol III.C.2 is also a mass preparative procedure, but differs from Protocol III.C.l in that it fixes the egg chambers immediately as they are released from... 

Both of these mass preparative procedures take advantage of the fact that egg chambers are among the densest of fly tissues and can therefore be separated from contaminants by repeated settling and washing. 

Allyl starch n. Soft, gummy mass prepared by the reaction of starch with allyl chloride in the presence of strong alkali. 

Figure 3. Method for Mass Preparation of Inclusion Conplex...

Such an apparatus is most time-saving when more than 100 TLC-plates are required daily. The experience gained in the film industry will have to be turned to account for mass preparation of TLC-plates or sheets, and preference given to a combination of conveyor belt and spraying procedure. 

Chart 1. Method for mass preparation of inclusion complex. 

The tyclic architecture was supported by a combination of techniques, including NMR, MALDI-TOF MS, and viscometry of the cyclic polymers in comparison with the linear homologs of the same molar mass (prepared in the presence of alcohol initiators). In addition, thermogravimetric analysis (TGA) suggested that cyclic PLAs were more thermally stable than the respective linear polymers. When IMes-mediated ROP was applied to optically pure l-LA, a crystalline isotactic cyclic PLA was formed, indicating that the polymerization occurred without epimerization of the chiral center. 

---