Gravimetric studies

These sites can be studied by electron paramagnetic resonance (EPR), ultraviolet (UV) spectrometry, x-ray photoelectron spectroscopy (XPS), and other methods. Besides, a quantitative study of redox sites can be carried out with the help of a volumetric or gravimetric study of the adsorption of the oxidizing or the reducing molecules. 

Quantitative information on the number of sites may be obtained from a volumetric or gravimetric study of the adsorption of oxidizing or reducting molecules. Adsorption calorimetry can be used to determine the energetics of the site distribution, as in the case of acidic and basic sites. 

Fig. 18. Details of electron heater used for precision evaporations in gravimetric studies. [After Rhodin, Disc. Faraday Soc. 5, 215 (1949).]...

Ouali M, Gousset H, Geinguenaud F, Liquier J, Gabarro-Arpa J, Le Bret M, Taillandier E. Hydration of the dT dA x dT parallel triple helix a Fourier transform infrared and gravimetric study correlated with molecular dynamics simulations. Nucl. Acids Res. 1997 25 4816-4824. 

A gravimetric study of the thermal dehydration of Y(HC00)j.2H20 was undertaken [149] in various water vapour pressures between 5 x 10" to 8 Torr (387 to 407 K). Following an initial short acceleratory process, the reaction predominantly fitted the contracting volume equation. The reaction rate increased with pQi20), reached a maximum value and thereafter decreased to a constant value. This is a pattern of behaviour similar to the Smith-Topley effect. The results are explained on the basis of the crystallinity of the dehydrated residual product. 

In a thermogravimetric investigation of the products of reaction between NaHCOj and HjOj, Firsova et al. [158] concluded that NajCOj.l.SHjOj decomposed exothermically, 383 to 413 K, followed by the endothermic desorption of water. Firsova and Filatov [159] reported a gravimetric study of the isothermal decomposition of sodium and potassium peroxocarbonates (MjCjOg) within the temperature interval 373 to 413 K. These compounds are prepared by the reaction of carbon dioxide with hydrogen peroxide in the presence of alkali, e.g. ... 

Kubsh, J.E. Dumesic, J.A. In situ gravimetric studies of the regenerative mechanism for water-gas shift over magnetite Equilibrium and kinetic measurements in CO and H gas mixtures. AIChE Journal 1982, 28 (5), 793-800. 

Buckton G, Darcy P. The use of gravimetric studies to assess the degree of crystallinity of predominantly crystalline powders. Int J Pharm 1995 123 265. 

For low percent styrene block copolymers surface energies approach their highest levels and surface oxygen content the lowest levels upon exposure to ozone. This mechanism appears to be different than the previous mechanisms and occurs only when styrene blocks are present in low concentrations compared to butadiene and also appear to reside preferentially at the surface. Infrared spectroscopy and gravimetric studies are currently being considered as further work in an attempt to answer some questions posed by this work. 

Bone, S. Dielectric and gravimetric studies of water binding to lysozyme, Phys. Med. Biol., 41,1265, 1996. 

This equation was determined using a catalyst similar to that used in the gravimetric study (U. The predicted rate of 2.1 x 10 m s" (for the case in which the partial pressures of both reactants and products are set equal to 10 kPa) agreed well with the experimental value of 7.3 x 10 m s . Furthermore, Figure 5 compares the experimentally determined effects of changing each of the constituent partial pressures from equation 13 to the effects predicted... 

In addition to the observation that the total uptake was only about 20% of the BET monolayer, in agreement with the previously discussed gravimetric studies, the data showed that when the CO2 pressure was increased at constant CO pressure, the amount of adsorbed CO decreased. Similarly, increasing the pressure of CO decreased the amount of adsorbed CO2. These results are consistent with adsorption on anion-cation pair-sites, where CO adsorbs on a cation and interacts with a neighboring anion, and where CO2 adsorbs as a bi dentate carbonate species. For competitive adsorption on a fixed number of surface sites, the coverages are given by the following expressions ... 

Two qualitative conclusions may be drawn from these fluorescence results. The first point is related to whether there is residual casting solvent that might affect the morphology of the film. It is not possible to comment on the presence of residual chlorobenzene or toluene from the results of this study because of the lack of any dramatic change in R or excimer band position upon annealing. No separate gravimetric studies of solvent evaporation were conducted in this work, although such experiments have been... 

Very few studies have been reported on the cleaning of hairspray resins from hair. In general, these resins are expected to be removed easily from hair due to their noncationic nature. This is consistent with a study by Sendelbach and co-workers [162] who reported 80 to 90% removal of different neutral or neutralized fixatives using a novel gravimetric study. Similar results were found in an experiment in the authors laboratories employing a radiolabeled ethyl ester of PVM/MA. In this experiment it was found that 89% of the resin was removed from wool swatches with a single washing with 10% ALS. 

This result implies that the oxygen occupancy in the xy plane adjacent to the Cu + ion changes from essentially no oxide ions along the a-axis and full occupancy along the b-axis (orthorhombic case) to where the occupancy is more equal for x > 0.5 (tetragonal case). The extreme case for x = 1.0 would have no vacancies in the xy plane around a Ni + (d -ion) if oxidation of the nickel has occurred. Gravimetric studies are presently underway to clarify... 

It must also be noted that a later mass-spectrometric and gravimetric study of this system at the same laboratory [1986FLE/KNA] indicates that the mass-spectrometry in the study by [1978KNA/MUN] may be flawed due to the use of bare metal heating elements. Flesch et al. [1986FLE/KNA] found that the iodine pressure from the decomposition of Thl4 was, in fact, less than 10% of that of Thl4(g). In view of this, and the reservations in the derivation of the results noted above, no data from this study has been accepted by the review. 

Challier and Slade [175] reported the synthesis of nanocoinposite materials consisting of polyaniline molecules encapsulated between ultra-thin mixed metal hydroxide sheets which are propped apart by spacers of terephthalate or hexacyanoferrate(II) ions acting as pillars. The layered double hydroxides (LDHs) were prepared by the method of Drezdon [176] which were refluxed with aniline to synthesize aniline intercalated LDHs. In thermo-gravimetric studies, terephthalate/Cu/Cr LDHs as well as hexa-cyanoferrate(lI)/Cu/Al LDHs showed weight losses in two steps attributed to the removal of trapped water and thermal breakdown of the intercalated systems. The former material exhibited somewhat better thermal stability than the latter one. 

Gravimetric studies were performed with a polystyrene-cyclohexane system. It was observed that there exists a critical particle size of the polymer, below which the dissolution time does not change. This critical size increased with an increase in the rate of stirring as shown in Fig. 9. The predicted dissolution times were compared to the actual dissolution times for PS dissolution in cyclohexane and reasonably good agreement was obtained as presented in Fig. 10. 

An isothermal gravimetric study of the same compounds (de Roy 1990) led us to study the hydration variations in relation to the relative humidity of the ambient atmosphere. The variations of the intracrystalline hydration are evidenced by the evolution of the basal... 

Catalysts and soot prepared by ink jet technology directly in cmcibles used for thermo gravimetric study... 

Barsan, M.M., Pinto, E.M., Brett, C.M.A. Methylene blue and neutral red electropolymerisation on AuQCM and on modified AuQCM electrodes An electrochemical and gravimetric study. Phys. Chem. Chem. Phys. 13, 5462-5471 (2011)... 

Heat-resistance and dielectric properties of the compositions with highest heat conductivity were studied. The thermo gravimetric studies showed that samples without fillers decompose at 340-345° C and samples with fillers - at 320-325° C. 

Tozzi S, et al. The effects of contact area and applied load on the morphology of in vitro worn ultra-high molecular weight knee prostheses a micro-Raman and gravimetric study. J Raman Spectrosc 2014 45(9) 781—7. 

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