Hard carbons comparison

The single-point BET surface area measurement was used to check for open pores. The results for some soft and hard carbon samples heated at 700°C and 1000°C are presented in Table 2 for comparison. The hard carbon samples studied here have about ten times more open porosity than the soft carbons. 

Comparison of the elemental depth profiles of the SEI (Figure 22) shows that, as with the LiPF electrolyte, the SEI formed on soft carbon is thinner. After 10 minutes of sputtering, the carbon concentration from the underlying HOPG approaches 80%, while for the hard carbon it does not exceed 30%. Eithium content remains relatively constant during sputtering, whereas the concentrations of carbon, oxygen, fluorine, and arsenic decrease monotonically. 

Hardness as calcium carbonate The expression ascribed to the value obtained when the hardness-forming salts are calculated in terms of equivalent quantities of calcium carbonate a convenient method of reducing all salts to a common basic for comparison. 

Spraying conditions make hardness values so variable that unless they are accurately known no comparisons are possible. Brinell hardness figures for sprayed molybdenum vary from 350 when produced with a reducing flame to 725 with an oxidising flame, and while a thick sprayed deposit of 0-8% carbon steel can give a figure of 330, the hardness of a particle obtained by micro hardness methods will be about 550. 

A comparison of the probabilities of the events (Table 1) for the catalysts 2 and 6 reveals that the basic difference between them is the reversed insertion regioselectivity the 2,1- insertion is preferred for 2, and the 1,2-insertion - for 6. In both cases the insertions happen only at the primary carbons, and in both cases the isomerization starting from the primary carbon has much lower probability than any insertion. Therefore, it comes as no surprise that the observed number of branches is that low for the system 2, since it is controlled only by the 1,2-/2,1- insertion ratio, as in system 6. However, it is quite surprising and hard to predict without simulations that the average isomerization/insertion ratio and especially the resulting microstructures of the polymers are so different for the two systems. Just because of the reversed insertion regioselectivity ... 

In terms of organic carbon generation, the coccolithophorids are a minor player, representing only 6 to 8% of global marine primary production. But their detrital remains contribute disproportionately to the burial of carbon in marine sediments. This is due to near complete loss of POC via remineralization as the detrital hard and soft parts settle to the seafloor. As estimated from Broecker s Box model in Chapter 9, only about 1% of the POM that sinks out of the surfece water is buried in marine sediments. In comparison, about 20% of the biogenic PIC survives to become buried in the sediments. 

Further examination of the results indicated that by invocation of Pearson s Hard-Soft Acid-Base (HSAB) theory (57), the results are consistent with experimental observation. According to Pearson s theory, which has been generalized to include nucleophiles (bases) and electrophiles (acids), interactions between hard reactants are proposed to be dependent on coulombic attraction. The combination of soft reactants, however, is thought to be due to overlap of the lowest unoccupied molecular orbital (LUMO) of the electrophile and the highest occupied molecular orbital (HOMO) of the nucleophile, the so-called frontier molecular orbitals. It was found that, compared to all other positions in the quinone methide, the alpha carbon had the greatest LUMO electron density. It appears, therefore, that the frontier molecular orbital interactions are overriding the unfavorable coulombic conditions. This interpretation also supports the preferential reaction of the sulfhydryl ion over the hydroxide ion in kraft pulping. In comparison to the hydroxide ion, the sulfhydryl is relatively soft, and in Pearson s theory, soft reactants will bond preferentially to soft reactants, while hard acids will favorably combine with hard bases. Since the alpha position is the softest in the entire molecule, as evidenced by the LUMO density, the softer sulfhydryl ion would be more likely to attack this position than the hydroxide. 

This assumption is based on the fact that PTFE agglomerates are soft and deformable particles in comparison to conventional (hard) fillers such as carbon black and silica for which (2) was originally derived. Morphological analysis (shown in Fig. 5) reveals that PTFE agglomerates can be considered as soft deformable particles. 

Comparison of Brinell, Vickers, Knoop, Rockwell and Shore hardness for carbon and low-alloy steels and roughly for all constructional and tool steels in various states of thermal processing... 

The comparison of CMC data in distilled vs. hard river water shows that the decrease in CMC with hardness has the order anionics cationics nonionics (Rosen et al., 1996). Hardness increases the dependence of the CMC on alkyl carbon chain length of CnE0mS04, indicating that in hard water the influence of additional carbon atoms is the same for CnE0mS04 as for CnEOm surfactants (Rosen et al., 1996). The influence of ionic strength on micellization of nonionic surfactants is due to a salting out effect of the hydro-phobic moiety of the surfactant molecule (Carala et al., 1994). 

Calcium borate-detergent and calcium carbonate-detergent hard-core RMs Calcium borate is stabilized in hard-core RMs with detergents such as sulfonate, salicylate and phenate and evaluated in comparison with calcium carbonate-detergent RMs. The hydrolytic stability, oxidation stability, thermal stability, friction and wear characteristics of both systems are shown in Table 3.7. Why have borate-detergent RMs been recently recognized as an efficient multifunctional class of anticorrosive-antiwear additive ... 

The yellow solution contains lead tetrachloride. It is puzzling to explain why lead dioxide will not react with two of the strong acids tried, yet does react with hydrochloric acid to give what is apparently a salt, PbCl4. The explanation lies in the character of lead tetrachloride, which is practically un-ionized, and therefore is hardly to be classed as a salt. In the anhydrous condition it is a liquid like carbon tetrachloride. Furthermore it combines with excess HC1 to form the complex acid H2PbCl6, of which the ammonium salt (NH4)2PbCl6 can be crystallized. By comparison, if nitric acid reacted with lead dioxide, the tetranitrate, Pb (NO3)4, would be the product this presumably would be highly ionized like all nitrates, which means that it would have to hydrolyze completely. 

In comparison to bulk plastics, thermoplastic polymethylmethacrylate (PMMA) is much more expensive. Its particular characteristics are clarity, hardness, low absorbance and resistance to aqueous solutions, acids, alkalis, carbon dioxide and fat. It is attacked or dissolved by polar organic solvents. The world-wide use of PMMA in 1997 was ca. 1.2 x 106 t, principaly for optical articles in cars and buildings and glazing material in aircraft. Typical food contact articles are dishes, cups and silverware. In addition it has orthopedic and denture uses. 

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