Interaction weighing

The chemistry of a single element is rarely the focal point of a symposium, but the occasion of the 40th anniversary of the first synthesis and weighing of pure compounds of plutonium suggested to us that such a symposium would be both timely and productive. The interest, enthusiasm, and stimulating interaction that the symposium generated showed that this supposition was indeed correct. 

That improper weighing (first hypothesis) is not a farfetched thought is demonstrated by observations of how workers interact with balances. It does... 

At room and higher temperatures the pattern of interaction between the singlet oxygen and anthracene changes. Changes in the mass of weighed sample of anthracene being acted upon by C>2( ) at room... 

Tissue Weigh sample homogenize in aqueous zinc acetate using a rotostator at 18,000 rpm for 20 seconds dilute with horate buffer convert to methylene blue. Ion-interaction reversed-phase HPLC nmol g 1 NR Mitchell et al. 1993... 

In order to estimate% conversion, precipitate was filtered, washed with C2H5OH and dried at 60°C before weighed. Different amounts of bismuth precipitated in solutions of bismuth nitrate, Bi(N03)3, of the concentration 0.071-0.111 M between the pH range 0.9-0.5 respectively, were estimated gravimetrically and given in the Table 9.16. These Bi3+ solutions were sonicated above autohy-drolytic concentration and pH. Hydrolysis began in the form of precipitate due to the formation of BiO(N03). At lower concentration [0.071 M of Bi(N03)3], precipitation started immediately upon sonication, whereas, the time for the appearance of turbidity increased as the concentration increased to 0.111 M. This was perhaps because of the availability of more water molecules for interaction with Bi3+ ions in dilute solutions. Ultrasonically induced hydrolysis was therefore... 

In flame retarding nonwovens, the contribution of components may not be additive. Rather, the interaction of binder, flame retardant, and substrate is critical in the performance of the flame retardant nonwoven. Similarly, the flammability of a binder film or the flammability of a flame retardant coated woven cloth often do not predict the flame retardancy of the same binder or flame retardant on a nonwoven substrate of rayon or polyester. Actual data on a nonwovens substrate is the only accurate measure of a system s flame retardancy. For this study, two widely used substrates were selected. The first, lightweight rando rayon, is representative of material used in nurse caps, surgeon s masks, and miscellaneous coverstock. This material is constructed of 1 1/2 denier fiber, weighs 1 1/2 ounces per square yard, and is relatively dense web. Rayon as a material is water absorbent, burns rather than melts, and is readily flammable. This fiber ignites around 400°C(2) and has an oxygen index of about 19.0. Certain binders adhere well to rayon while others do not. Apparently, this lack of affinity for the substrate affects flame retardancy, as will be demonstrated later. 

The SANS experiments [51] were performed with solutions of G8 PAMAM dendrimer in D20, methyl-d4, ethyl-d6, and n-butyl-d10 alcohol at a temperature of T = 20.0 °C. PAMAM dendrimers do not dissolve in acetone, but they readily dissolve in methyl alcohol/acetone mixtures over a wide range of composition. Solvents of different composition, were prepared and added to a weighed amount of dried G5 or G8 dendrimer. In a separate set of experiments, the NIST NG7 30 m instrument was used to measure the effects of charging on the dendrimer size. PAMAM G8 dendrimers in D20 were charged by addition of HC1 in the presence of various amounts of NaCl to the charged dendrimers to screen the electrostatic interactions. 

A sample of specified weight is normally required in the procedure. An interactive form of weighing is used, in which the display or printing unit of the entry station indicates whether or not the sample has been accepted. Before analysis it is necessary to specify the code number of the analytical method that is to be used, and to store this in the memory of the central control. To indicate where samples are located, it is necessary to identify them before weighing. Optical readers are therefore mounted on the sample-transport mechanism to register each sample. The sample is identified by a unique code placed on the outside of the sample cup. 

The relative SAA s of the surface atoms that may later be used as weighing factors in estimations of the surface-solvent interactions. 

In recent years much has been learned about the chemical structure of certain receptors. The nicotinic receptor on skeletal muscle, for example, is known to be composed of five subunits, each a glycoprotein weighing 40,000 to 65,000 daltons. These subunits are arranged as interacting helices that penetrate the cell membrane completely and surround a central pit that is a sodium... 

Finally, we note that carbon balance closures are generally poorer in the alcohols than in water. A control experiment in which the entire reaction was carried out without sample collection, and another in which reactor and contents were carefully weighed at each stage of reaction, offered no hint as to the fate of lost GO or products. We measured gas formation in the reactor headspace and found < 1% of initial carbon present as gaseous products, primarily methane. We suspect that glycerol and alcohols are forming ethers at the elevated reaction temperatures, and that these ethers are not detected in HPLC. We are continuing efforts to better understand interactions of the solvents with substrates and reaction products. 

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