Mass characterization

Many curing systems bring about aHquid—to—soHd conversion of the polysulfide polymers. Most curing agents produce an initial soHd mass characterized by a high degree of plasticity and poor elasticity. The development of elastic properties is so slow that the materials are not suitable for the accurate reproduction of undercut areas found ia oral stmctures. 

A summary of typical experimental conditions used with TSK-PW columns for nonionic polymers is described in Table 20.3. A common mobile phase is an aqueous solution of 0.05 N sodium nitrate. A salt solution of sodium nitrate is a good choice because it is not as corrosive as a solution of sodium chloride. For the descriptions and examples that follow, a bank of either five or six TSK-PW columns in series (G1000-G5000 or G1000-G6000) was used for the aqueous SEC work. These configurations allow for molecular mass characterization from less than 1,000 Da to 1,000,000 Da or greater. 

Cape Grim is an ideal location to study free-radical chemistry in extremely clean conditions (Penkett et al., 1997). It frequently experiences air masses characterized by low condensation nuclei (CN) and Radon counts (<462 cm-3 and < 100 mBq m-3, respectively) with the local wind direction in the sector 190°-280°. In these baseline conditions, air has not passed over land for 5 days or more and is therefore relatively free of anthropogenic influence. Four days, which were characterised by the lowest NOx and NMHCs levels experienced during the campaign, have been selected to be representative of baseline conditions in the Southern Ocean. 

Zubarev, R.A. Demirev, P.A. Hakansson, P. Sundqvist, B.U.R. Approaches and Limits for Accurate Mass Characterization of Large Biomolecules. Anal. Chem. 1995, 67, 3793-3798. 

Erom Equations 12.46 and 12.47, one sees that ThEEE retention is related to (l/5j), but not specifically to a conventional analyte property, such as molar mass M or particle diameter d. However, since HSj depends on M or d, it also mediates the dependence between R and M or d. At constant Tq conditions, the relationship between X, M, and AT can be experimentally exploited by using standards. Eor instance, in polymers mass characterization, monodisperse or polydisperse standards can be employed for a specific polymer-solvent system. Once the relationship X vs. M, that is, the so-called calibration curve, is obtained, it is universal, that is, valid for any ThFFF instrument [3]. A typical calibration function, which relates the instrumental response to analyte property (in this case M), is... 

Grades of butyl differ by the level of unsaturation, molar masses characterized by Mooney viscosity ML 1 + 8 (100 or 125° C), and the characteristics of the eventually added stabilizer (staining or nonstaining). Butyl rubber, which ranks third in total synthetic elastomers consumed, has unique properties and applications, due to its low gas permeability, to its high hysteresis, and to its low level of unsaturation, sufficient for vulcanization but still providing excellent resistance to oxygen and ozone. 

C. Edwards, J. Liu, T. J. Smith, D. Brooke, D. J. Hunter, A. Organ, and P. Coffey, Parallel preparative high-performance liquid chromatography with on-line molecular mass characterization. Rapid Commun. Mass Spectrom. 17 (2003), 2027-2033. 

In contrast to previous publications, we wanted to create chemically homogeneous fractions in the first separation and work on these for molar mass characterization. Therefore, HPLC (or LACCC) was the first and SEC the second separation method. The advantages of this setup are numerous. LC has more parameters (gradient, stationary phase, etc.) to adjust the separation according to the chemical nature of the... 

Petrovas C, Mueller YM, Dimitriou ID et al (2007) Increased mitochondrial mass characterizes the survival defect of HIV-specific CD8(+) T cells. Blood 109(6) 2505-2513... 

P. Parallel Preparative High-performance Liquid Chromatography with On-line Molecular Mass Characterization, Rapid Commun. Mass Spectrom. 17, 2027-2033 (2003). 

The FEBEX in situ test started in 1995 with rock-mass characterization and tunnel excavation. After the installation of heaters, the bentonite barrier, and monitoring equipment, the heating... 

We have emphasized that the modelling and the associated rock mass characterization should be determined by the rock engineering objective. This means that different types of information will be required for THMC modelling for the different types of application, as illustrated by the themes of this conference and the associated papers. However, site investigation has limited methods of approach, e.g. surface outcrop studies, borehole and borehole core measurements, and geophysics, which means that we will not have as much information as we would like and concessions have to be made on both the site investigation and modelling sides. 

The pol5mier has a broad compatibiUty with chemicals and solvents, offering a better chemical resistance than stainless steel. No solvent for PPS is known below 200°C. Above this temperature, 1-chloronaphthalene is a suitable solvent. Molecular mass, characterization e.g., by size exclusion chromatography at moderate temperatures can be done only when derivatives are formed prior to analysis in order to enhance the solubility. The sulfide groups are oxidized, by a mixture of nitric acid and methanesulfonic acid resulting in a poly(p-phenylene sulfoxide) (PPSO) polymer. Actually, methanesulfonic acid is a solvent for PPSO. 

Milne D, Hadjigeorgiou J Pakalnis R. 1998. Rock mass characterization for tmderground hard rock mines. Tunnelling and Underground Space Technology (13) 383 391. 

Separation/mass characterization (dissolved proteins depletion method) Ultracentrifugation... 

Prior to the introduction of SEC, polymer molecular mass characterization was generally very difficult and time-consuming. SEC permits this characterization to be carried out relatively routinely. However, the variation of results between laboratories, and even within a single laboratory over a period of time, has made this characterization somewhat questionable. 

Lloyd, P.M., Suddaby, K.G., Varney, J.E., Scrivener, E., Derrick, P.J., and Haddleton, D.M. (1995) A comparison between matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and size exclusion chromatography in the mass characterization of synthetic polymers with narrow molecular-mass distributions poly(methyl methacrylate) and poly (styrene). Eur. Mass Spectrom.,... 

Adnexal Masses Characterization of Benign Ovarian Lesions 199... 

The average molar mass is of crucial importance for polymers. The average molar mass characterizes the chain length of a polymer molecule, which is of great importance to the processing and overall performance of the polymer as described below. 

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