Additional analyses

Another possible evidence of grafted organic/polymeric molecules onto CNT surface can be achieved by microscopy analyses using both principal types of electron microscopy - transition electron microscopy, TEM, or scanning electron microscopy, SEM (15,19,24,44,45,47). Such analyses are usually performed after careful extraction of the polymer from tubes by polymer solvents, performed several times by a reflux procedure with an excess of solvent therefore it is supposed that only covalently attached molecules remain fixed at CNT surface. High Resolution mode of TEM analysis shows the evidence of amorphous material on nanotubes surface (15). 

Typical products of suspension polymerization techniques are polymer beads or spheres with a diameter of 50 pm - 2 mm. The 

Part (a) presents carbon nanotubes purified by acid-treatment (leading also to shortening of tubes), and part (b) shows PMMA spherical particles together with individualized MWCNT tubes, which seem to connect particles (16,18). 

In consequent experiments, the authors (16) innovated the preparation procedure in order to improve the quality of prepared PMMA/ MWCNT particles they profitably used a steric stabilizer, poly(vinyl pyrrolidone) (PVP) (48). PVP has both hydrophobic and hydrophilic 

The product of the innovated polymerization procedure described above shows a uniform size distribution of spherical particles, with spheres size of 8 pm, contrary to polydispersed MWCNT/PMMA particles 1—12 pm in diameter. The polydispersity may originate from the presence of MWCNT particles (48), and the size of final MWCNT/PMMA spheres depends on MWCNT concentration and size and also on the level of MWCNT aggregation and the number of individual MWCNTs involved in the formation of composite particles. The presence of nanotubes in PMMA/MWCNT composites was confirmed by SEM analysis, which identified a large amount of MWCNTs at the surface of the composite spheres. Some of them are just adhered on PMMA spheres surface but others come into bulk of PMMA matrix. It was also confirmed by TEM analysis that nanotubes are well embedded in the surface of PMMA particles and even more, they are present inside individual PMMA/MWCNT particles. 

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It should be cautioned that the correctness of the factors involving z has not really been verified experimentally and that the algebraic forms involved are modelistic. Additional analyses have been made by Ruckenstein and Dadybur-jor[lll]. 

This experiment describes the adaptation of the bicinchoninic acid (BCA) protein assay to a flow injection analysis. The assay is based on the reduction of Cu + to Cu+ by the protein, followed by the reaction of Cu+ with bicinchoninic acid to form a purple complex that absorbs at 562 nm. Directions are provided for the analysis of bovine serum albumin and rabbit immunoglobulin G, and suggestions are provided for additional analyses. 

The most common chromatogram in the distilled spirits industry is the fusel oil content. This consists of / -propyl alcohol, isobutyl alcohol, and isoamyl alcohol. Other common peaks are ethyl acetate, acetaldehyde, and methanol. The gc columns may be steel, copper, or glass packed column or capillary columns. Additional analyses include deterrninations of esters, total acids, fixed acids, volatile acids, soHds or extracts (used to determine... 

Ingredients. Ingredients used in the manufacture of carbonated beverages must meet all Food Chemical Codex specifications and be approved for use in soft drinks by the FDA. In addition to the government stated specifications, manufacturers of carbonated beverages may complete additional analyses based on specific needs or concerns. 

When a test run is performed using the actual materials for the toll, it is a prime opportunity for the toller and the client to document the capability of the equipment, instrumentation, and process steps. During such a test, frequency of sampling may be increased, additional analyses performed and yield capabilities checked to find the optimum setpoints and timing for the toll process. Health, safety and environmental staff may choose to provide close coverage of the test run to evaluate areas for improvement during the actual startup and long term operation. 

The problem could have been resolved by running two injections, either with different wavelength settings and/or with different dilutions injected, but this would have appreciably increased the workload of the technicians and the utilization factor of the instrument. Without an additional instrument, the laboratory would have lost much of its flexibility to schedule additional analyses at short notice. Another solution would have been to utilize a programmable detector that switches wavelengths between peaks, but that only works if the weakly detected component strongly absorbs at some other wavelength. 

The typical product of a traditional analytical method is a static, paper report. Such reports usually consist of a vast number of discrete, personal, ad hoc processes that cannot typically be used to perform subsequent comprehensive reproducible analyses as soon as additional analyses are needed. Having an... 

The scanning transmission electron microscope (STEM) was used to directly observe nm size crystallites of supported platinum, palladium and first row transition metals. The objective of these studies was to determine the uniformity of size and mass of these crystallites and when feasible structural features. STEM analysis and temperature programmed desorption (TPD) of hydrogen Indicate that the 2 nm platinum crystallites supported on alumina are uniform In size and mass while platinum crystallites 3 to 4 nm in size vary by a factor of three-fold In mass. Analysis by STEM of platinum-palladium dn alumina established the segregation of platinum and palladium for the majority of crystallites analyzed even after exposure to elevated temperatures. Direct observation of nickel, cobalt, or iron crystallites on alumina was very difficult, however, the use of direct elemental analysis of 4-6 nm areas and real time Imaging capabilities of up to 20 Mx enabled direct analyses of these transition metals to be made. Additional analyses by TPD of hydrogen and photoacoustic spectroscopy (PAS) were made to support the STEM observations. 

Crompton [88,89] has regularly provided detailed accounts of the scientific principles underlying current practice, targeted mainly at the experienced industrial technologist. An extensive review on polymer/additive analyses (period 1960-1980) is contained in Crompton... 

I were obtained in 10 min for both 20- and 30-mesh grinds. Ten-minute extractions are sufficient to ensure that all additives have been extracted, but it is brief enough that smaller, more volatile additives are not lost. Recovery and precision data for several other additives in II were also reported. Extraction results with microwave heating in isobutanol or isopropanol compared with a 60 min reflux extraction also show good reproducibility (<3 % RSD for all additives analysed). 

Applications Chromatography is a preferred technique for additive analysis as it allows both separation of additives in a mixture and subsequent quantitation. Despite the developments in GC, this technique cannot separate many polymer additives. Even with its lower efficiency in comparison to GC, HPLC is today one of the cornerstones in a polymer additive laboratory. Judging by the number of publications in recent years, HPLC is first among analytical methods for additives (confirmation/identification/quantification). Most additives may be analysed by HPLC if they can be dissolved in an HPLC solvent and absorb UV light. Typical polymer/additive analyses are carried out using LPE followed by HPLC with UV or RI detection [605-611]. Verification of the identity of an analyte is then based on a combination of retention time, UV and RI evidence. RPLC is used most frequently for polymer/additive analysis, but normal-phase and SEC are also used. Consequently, techniques for additive analysis by HPLC are legion. 

Many industrial laboratories conducting significant amounts of additive analyses have developed a universal HPLC method which may be used to separate most of the additives of interest. Thomas [417] has reported a method that can separate over 20 common primary and secondary stabilisers. Verdurmen et al. [197] employ a gradient ranging from 60 % acetonitrile/40 % water to 100% acetonitrile subsequently, all components are eluted off the column in isocratic mode. Irganox 1063 is used as a suitable internal standard since this compound is not frequently encountered in commercial polymers, elutes without overlap to other additives and shows good UV absorbency. In order... 

For polymer/additive analyses neither a very high mass range nor an ultrahigh mass resolution is required isobaric additive ions are not frequent. It is therefore not surprising that tandem sector instruments have not found wide application for polymer/additive identification. 

The EU Directive on Packaging and Packaging Waste sets a recovery target for used packaging of 25% by 2001 and 50-65% by 2005. It is likely that recycling of postconsumer plastics will require substantial polymer/additive analyses. 

Additional analyses of the same data set by Pirkle et al. (1985) focused on white males (40-59 years of age) revealed significant correlations between PbB level and blood pressure. No threshold was found... 

Although additional analyses of the existing data and additional experiments are required to reach definitive conclusions on the phase changes of ferrihydrite in uranium mine tailings, preliminary XRD data suggest that in deionized water at elevated pH (pH=10) phase transformation of ferrihydrite can occur at elevated temperatures. In both elevated temperature experiments, hematite appeared to be the dominant transformation product. At room temperature, however, ferrihydrite remains stable after the duration of the experiment (seven days). 

An association between meat use and fatal prostate cancer is evident in Table II, although it is not statistically significant. Additional analyses (not shown on table) show a similar degree of association between use of other animal products (eggs, milk, cheese) and fatal prostate cancer. If use of all four animal products are combined into an index which reflects their combined use, a very clear relationship emerges (Table III). Thus, it appears that heavy use of all four animal products is associated with a three-fold increase in risk of fatal prostate cancer. 

Desalted peak fractions were analyzed by both IP-RP-HPLC and RP-HPLC (derivatized with FMOC-Cl) to investigate the presence of pyridinoline- and lysinonorleucine type cross-links, respectively. Two fractions. 111 and V-1-1, were found to contain the cross-links HP and DHLNL, respectively. Additional analyses by cation exchange HPLC showed TV and V-2 as closely eluting peaks and VI as a mixture of lysi-noalanine and an unidentified amino acid (fig. 3a). 

Additional analyses are required and special building design features may be needed if the control building in its planned or existing location is exposed to more severe hazards, such as ... 

Based on these four rules, Cameron and Papike (1982) selected 175 analyses out of 405 reported by Deer et al. (1978) and discarded 230 compositions. This selection is extremely rigorous and does not take into account either the possible stabilization of Fe in tetrahedral sites or the existence of extrinsic disorder (cf chapter 4). Robinson (1982) showed that, by accepting a hmited amount of cationic vacancies in M2 sites and assuming possible stabilization of Fe in tetrahedral positions, 117 additional analyses out of the 230 discarded by Cameron and Papike (1982) may be selected. 

Subsequent analysis of the ashed needles from these twigs confirmed the patterns established from the dry twigs. It served to enhance some signatures (notably Ag) and added a layer of data for the halogens, demonstrating a F association. Also from these additional analyses a pattern of Cd and B enrichments at Kingfisher was evident. 

In an attempt to determine whether the carcinogenicity observed in animal studies was predictive for humans, the mortality experience of ammunitions workers with opportunity for substantial DNT exposure was examined. No evidence of carcinogenic effect was found, but an unsuspected excess of ischemic heart disease was noted. Additional analyses showed evidence of a 15 -year latency period and suggested a relationship with duration and intensity of exposure. ... 

In like vein, we would recommend the use of more than just one evaluation measure. That said, it is our experience that different measures usually agree as to the relative merits of different approaches (unless there are only very minor differences in effectiveness) even so, it is always worth carrying out additional analyses to ensure that one s results are, indeed, independent of the evaluation criterion that has been adopted. 

If a laboratory conducts a blanket analysis for contaminants, the protocol can make reference to a description of those analyses in laboratory SOPs. Any additional analyses that are specific to the study should be described in the protocol. 

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