Ampule sealing

III) species into active Cu(I) and Fe(II), respectively.230 The 1-13 (X = Br)/CuBr2/Cu(0)/L-4 system induced a fast polymerization of unpurified styrene at 110 °C to reach 90% conversion within 2 h. Controlled molecular weights and narrow MWDs are available even when the polymerization is performed in ampules sealed in air. However, no polymerization occurred open to air. 

The studies of Criddle et al. [17] on carrot and tomato cell cultures outlined basic procedures for isothermal heat rate measurements of plant tissues. Samples are placed in an ampule, sealed to prevent any water vapor loss, placed in the calorimeter at the desired temperature and the heat rates recorded directly. Figure la shows the type of thermogram obtained. There is an initial rapid change in recorded heat rate while sample and ampules are thermally equilibrated. Following equilibration, (about 45 min in this example) the amplitude of the thermal signal is corrected for baseline values obtained with empty ampules to yield the sample metabolic heat rate. Temperature may then be adjusted to new values to establish temperature coefficients of heat rate or the ampules may be opened and the sample environment modified before the ampule is resealed and re-equilibrated for evaluation of effects of the modification on plant activities. Because plants are ectotherms that live in a variable temperature environment, temperature dependence studies using sequential i.sothermal mea.surements are essential for characterization of plant physiological properties. 

Figure 1. Isothermal measurement of plant metabolic heat rates. Plant tissue samples are placed in the calorimeter ampules, sealed, and heat rates are followed over time. The initial rapid changes in heat rates observed in this figure illustrate thermal equilibration of ampules and samples. This is followed by heat rate values that, when adjusted for any baseline corrections, represent the metabolic heat rate of the tissue preparation. When tissue metabolic rates are stable over the time course of the experiment, constant heat rates are obtained (a). When tissues are unstable or are stressed so that metabolic activity decreases during the calorimetric measurement, a decreasing heat rate is ob.served (b).

Anhydrous, monomeric formaldehyde is not available commercially. The pure, dry gas is relatively stable at 80—100°C but slowly polymerizes at lower temperatures. Traces of polar impurities such as acids, alkahes, and water greatly accelerate the polymerization. When Hquid formaldehyde is warmed to room temperature in a sealed ampul, it polymerizes rapidly with evolution of heat (63 kj /mol or 15.05 kcal/mol). Uncatalyzed decomposition is very slow below 300°C extrapolation of kinetic data (32) to 400°C indicates that the rate of decomposition is ca 0.44%/min at 101 kPa (1 atm). The main products ate CO and H2. Metals such as platinum (33), copper (34), and chromia and alumina (35) also catalyze the formation of methanol, methyl formate, formic acid, carbon dioxide, and methane. Trace levels of formaldehyde found in urban atmospheres are readily photo-oxidized to carbon dioxide the half-life ranges from 35—50 minutes (36). 

The bulk polycondensation of (10) is normally carried out in evacuated, sealed vessels such as glass ampules or stainless steel Parr reactors, at temperatures between 160 and 220°C for 2—12 d (67). Two monomers with different substituents on each can be cocondensed to yield random copolymers. The by-product sdyl ether is readily removed under reduced pressure, and the polymer purified by precipitation from appropriate solvents. Catalysis of the polycondensation of (10) by phenoxide ion in particular, as well as by other species, has been reported to bring about complete polymerisation in 24—48 h at 150°C (68). Catalysis of the polycondensation of phosphoranimines that are similar to (10), but which yield P—O-substituted polymers (1), has also been described and appears promising for the synthesis of (1) with controlled stmctures (69,70). 

Commercially available containers for use with parenteral products include single-dose ampuls that are heat sealed and opened by snapping at the point of least diameter, vials for multidose use, and botdes and pHable bags that are used for large volumes such as needed in intravenous infusions. Container size can vary from 1 mL to 1 L. Generally volumes up to 100 mL are available as ampuls or vials. 

Statistical control of an analysis or instmment is best demonstrated by SQC of a standard sample analysis. The preferred approach to demonstrate statistical control is to use a reference sample of the subject material that has been carefully analyzed or, alternatively, to use a purchased reference standard. Either material must be stored so that it remains unchanged, eg, sealed in ampuls or septum capped bottles. Periodically a sample can then be reanalyzed by the technique used for routine analysis. These results are plotted in a control chart. Any change in the stabihty of the test in question results in a lack of... 

At temperatures above 150°C, dehydration continues to yield viscous Hquid phases beyond the metaboric acid composition (39). The most stable form of metaboric acid, cubic HBO2-I or y-form (d = 2.49 g/mL, mp = 236° C) crystaUi2es slowly when mixtures of boric acid and HBO2-III are melted ia an evacuated, sealed ampul and held at 180°C for several weeks (41). 

The samples were collected and processed in a manner to avoid exposure to oxygen and control loss of moisture then they were pulverized to convenient sizes for research, ie, <149 fim ( — 100 mesh) and <840 fim (—20 mesh) the entire ton was thoroughly mixed and packaged in sealed glass ampules under nitrogen. These samples have been well characterized and are available in quantities that are expected to last for decades (Table 8). 

Pelargonyl chloride (nonanoyl chloride) [764-85-2] M 176.7, b 88 /12mm, d 0.941, n 1.436. Refluxed with acetyl chloride ( 3 vols) for Ih, then distil off the AcCl followed by the nanoyl chloride under reduced pressure. It is moisture sensitive and should be stored in sealed ampules. 

Soianone [5( + )-/rn s-2-methyi-5-isopropyi-l,3-nonan-8-one] [1937-54-8] M 194.3, b 60< /lmni, [alp +14" (neat). Purified by high vacuum distillation and stored in sealed ampules [Kohda and Sato J Chem Soc, Chem Commun 951 7957]. It has UV (hexane) at Xmax 230nm (e 11,800). 

Titanium tetrabromide [7789-68-6] M 367.5, m 28.3°, b 233.5 , d 3.3. Purified by distn. Distillate forms light orange hygroscopic crystals. Store in the dark under N2 preferably in sealed brown glass ampules. [Olsen and Ryan J Am Chem Soc 54 2215 1932.]... 

The only known representative of this type of compound, 91, was prepared by 1,3-dipolar addition of mesityl nitrile oxide to telluroketone 85 (93JA7019 94MI1). The reaction proceeds smoothly on heating equimolar amounts of the reactants at 80°C, giving rise to 91 in 70% yield. The heterocycle is a thermally unstable and light-sensitive compound. Thermolysis of a deuterochloroform solution of 91 at 60-90°C in a sealed ampule affords 1,1,3,3-tetramethylindanone and mesityl isonitrile (94MI1). 

Galy, Andersson and Portier reported on the thermal treatment (at 700°C), in a sealed ampule, of a mixture containing LiF, Nb205 and NbF5, leading to the preparation of Li2NbOF5 [81]. 

The thermolysis of aryl azides in alcoholic solution has been used to prepare 2-alkoxy-37f-azepines. Thermolysis of 3-azidophenyl methyl ketone in methanol in a sealed ampule furnishes a mixture of the 6-acetyl- (36a) and 4-acetyl-2-methoxy-3//-azepine (37a) in superior yields to those obtained in the corresponding photolytic reaction.78 Other 3-substituted azides behave similarly, with a preference for the 6-substituted isomers 36, as is observed for azide photolyses in amine solutions. 

Stability. It may be stored indefinitely at 0° in sealed glass ampules (Ref 20)... 

Refs 2 5). It is extremely sens and can expld without provocation at any time, but can be stored indefinitely at low temp in sealed ampules when shielded from light (Ref... 

The chloride is mixed on a laboratory scale with xs Ca (powder or chips) in an Fe tube in a high-T glass distillation vessel. The Fe tube protects the glass from corrosive attack by the alkali-metal vapors. The vessel is inclined and evacuated while slowly heating to 700-800°C. The liberated Rb or Cs distills onto the cooler upper walls of the vessel and runs into integral glass ampules, which are sealed under vacuum for storage. Further purification is achieved by repeated. vacuum distillation at 300°C. Yields arc theoretical. 

A Comparison of the Stabilities of N-Nitroso Compounds in Sealed Ampules during Heating (79)... 

Materials. Ethylene Oxide (EO) and pivalolactone (PVL) were dried over calcium hydride for a day before use. EO was further dried on a sodium mirror prior to passing into the reaction vessel. Dried PVL was sealed into ampules under high vacuum (I0"° mm Hg). Succinic anhydride (SA) was dried in a vacuum oven for a day and sublimed under high vacuum into ampules. Dry THF was obtained by refluxing THF on Na/K (1 1) alloy for six hours, distilling over the alloy and degassing under high vacuum in the... 

The protection of a drug substance from the destructive influences of atmospheric oxygen or humidity (such as coated tablets, sealed ampuls)... 

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