Harder

Influence of operating conditions This concerns the temperature, the pressure and the residence time. The more severe the conditions are, the harder is the coke produced. 

Influence of the type of process fluid coking", compared to delayed coking" makes a harder coke that contains less volatile matter and forms finer grains. 

The accuracy of the calculated solution is highly depending of realistic values for conductivity and permeability of the tube material. While the conductivity can be found in the literature for most materials, the right permeability is harder to determine. In the RFEC technique the exciter current and thus the exciter field strength is often to high to assume a... 

An indirect estimate of surface tension may be obtained from the change in lattice parameters of small crystals such as magnesium oxide and sodium chloride owing to surface tensional compression [121] however, these may represent nonequilibrium surface stress rather than surface tension [68]. Surface stresses may produce wrinkling in harder materials [122]. 

Bikerman [182] criticized the derivation of Eq. X-18 out of concern for die ignored vertical component of On soft surfaces a circular ridge is raised at the periphery of a drop (see Ref. 67) on harder solids there is no visible effect, but the stress is there. It has been suggested that the contact angle is determined by the balance of surface stresses rather than one of surface free energies, the two not necessarily being the same for a... 

Shifts can also be predicted ftom basic theory, using higher levels of computation, if the molecular structure is precisely known [16], The best calculations, on relatively small molecules, vary from observation by little more than the variations in shift caused by changes in solvent. In all cases, it is harder to predict the shifts of less coimnon nuclei, because of the generally greater number of electrons in the atom, and also because fewer shift examples are available. 

The technological importance of thin films in snch areas as semicondnctor devices and sensors has led to a demand for mechanical property infonnation for these systems. Measuring the elastic modnlns for thin films is mnch harder than the corresponding measurement for bnlk samples, since the results obtained by traditional indentation methods are strongly perturbed by the properties of the substrate material. Additionally, the behaviour of the film under conditions of low load, which is necessary for the measnrement of thin-film properties, is strongly inflnenced by surface forces [75]. Since the force microscope is both sensitive to surface forces and has extremely high depth resolntion, it shows considerable promise as a teclnhqne for the mechanical characterization of thin films. 

Harder P, Grunze M, Dahint R, Whitesides G M and Laibinis P E 1998 Molecular conformation in oligo(ethylene glycol)-terminated self-assembled monolayers on gold and silver surfaces determines their ability to resist protein adsorption J. Rhys. Chem. B 102 426-36... 

Feldman K, Hahner G, Spencer N D, Harder P, and Grunze M 1999 Probing resistance to protein adsorption of oligo(ethylene glycol)-terminated self-assembled monolayers by scanning force microscopy J. Am. Chem. Soc. at press... 

Later in this section, we shall specify the analytic properties of the functions involved and obtain exact formulas similar to Eqs. (9) and (10), but less simple and harder to apply to observational data of, say, moduli. 

From Table 6.1, it is easy to see that Group II metals are more dense, are harder and have higher m.p. and b.p. than the corresponding Group I metals. 

By subjecting boron nitride (a white powder) to high pressure and temperature small crystals of a substance harder than diamond, known as borazon, are obtained. This pressure-temperature treatment changes the structure from the original graphite-like layer structure (p. 163) to a diamond-like structure this hard form can withstand temperatures up to 2000 K. 

It is immediately obvious that the transition metals are more dense, harder, and have higher melting points and boiling points than the main group metals (for example, the metals of Group II,... 

Because the metal structure is locked by these atoms, the resulting compound is often much harder than the original metal, and some of the compounds are therefore of industrial importance (see under iron). Since there is a definite ratio of holes to atoms, filling of all the holes yields compounds with definite small atom-metal atom ratios in practice, all the holes are not always filled, and compounds of less definite composition non-stoichiometric compounds) are formed. 

Cyclohexylidenes are slightly harder to cleave than acetonides... 

Pure silver has a brilliant white metallic luster. It is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. It is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur. The alloys of silver are important. 

Once a rubberband is stretched beyond its elastic region, it becomes much harder to stretch and soon breaks. At this point, the polymer chains are linear and more energy must be applied to slide chains past one another and break bonds. Thus, determining the energy required to break the material requires a different type of simulation. 

Nevertheless, the puzzling fact to be explained is that the harder ring nitrogen prefers the softer electrophilic center and that this preference is more pronounced than the one observed for the amino nitrogen. Much remains to be done to explain ambident heterocyclic reactivity it was shown recently by comparison between Photoelectrons Spectroscopy and kinetic data that not only the frontier densities but also the relative symmetries of nucleophilic occupied orbitals and electrophilic unoccupied orbitals must be taken into consideration (308). 

The decrease in the acid dissociation constant from K i to tells us that each successive proton is harder to remove. Consequently, H3PO4 is a stronger acid than H2P04, and H2P04 is a stronger acid than HP 04 . 

Chemical shifts can be observed for atoms in both organic and inorganic materials. Generally, E increases as the oxidation state of the atom increases. This dependence can be rationalized on the basis of simple electrostatic considerations in terms of an increased attraction for the electron by the atom making it that much harder to remove. These chemical shifts can range in magnitude from <1 eV to >10 eV. 

The combination of durability and clarity and the ability to tailor molecules relatively easily to specific applications have made acryflc esters prime candidates for numerous and diverse applications. At normal temperatures the polyacrylates are soft polymers and therefore tend to find use in applications that require flexibility or extensibility. However, the ease of copolymerizing the softer acrylates with the harder methacrylates, styrene, acrylonitrile, and vinyl acetate, allows the manufacture of products that range from soft mbbers to hard nonfilm-forming polymers. 

Heating is usually accompHshed with a semiclosed loop which has a constant fresh gas makeup and a bleed to draw off the desorbed material. However, contaminant is at a higher level than in an open loop and product purity is harder to achieve. 

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