Republic Oil Co., El Segundo 1


A second type of repulsion could be long range. If adsorption bond formation polarizes the adsorbate, or strongly orients an existing dipole, the adsorbate film will consist of similarly aligned dipoles that will have a mutual electrostatic repulsion. The presence of such dipoles can be inferred from the change in surface potential difference AV on adsorption, as mentioned in Section IV-3B. The resulting interaction should show both a short-range Coulomb repulsion due to adjacent dipoles whose positive and negative charges would repel each other, and which could be considered as part of oi, and a long-range repulsion due to the dipole held, which is inverse cube in distance.  [c.701]

The analysis of tlie interface distribution fimction g r) is relatively straightforward [33]. The profile of g r) can be directly calculated from the Fourier transfomiation of the interference fimction or by taking the second derivative of the correlation fimction (B 1.9.102). In the physical sense, the interface distribution fimction represents the probability of finding an interface along the density profile. A positive value indicates an even number of interfaces within a real space distance with respect to the origin. A negative value indicates an odd number of interfaces within the corresponding distance. With lamellar morphology, odd numbers of interfaces correspond to integral numbers of long periods. The shape of tlie probability distribution with distance for a given interface manifests as the shape of the corresponding peak on the interface distribution fimction. These distributions can be deconvoluted to reveal more detailed morphological parameters [34]- The schematic diagram of the relationships between the one-dimensional electron density profile, p(r), correlation fimction.  [c.1407]

The explorative analysis of data sets by visual data mining applications takes place in a three-step process During the first step (overview), the user can obtain an overview of the data and maybe can identify some basic relationships between specific data points. In the second step (filtering), dynamic and interactive navigation, selection, and query tools will be used to reorganize and filter the data set. Each interaction by the user will lead to an immediate update of the data scene and will reveal the hidden patterns and relationships. Finally, the patterns or data points can be analyzed in detail with specific detail tools.  [c.476]

Furthermore kinetic studies reveal that electrophilic addition of hydrogen halides to alkynes follows a rate law that is third order overall and second order in hydrogen halide  [c.378]

Kinetic studies of these reactions reveal that they follow a second order rate law Rate = [Aryl halide] [Nucleophile]  [c.977]

For a second series of measurements, the precision is much better than for the series shown in Figure 48.7. Neither Figure 48.8 nor Figure 48.7 reveal any information on the accuracy of measurement.  [c.363]

Considering our approach to the topic, we might be tempted to believe that the second virial coefficient is small for a polymer, depending as it does in Eq. (8.87) on M . Experimental results such as those shown in Fig. 8.9, however, reveal that plots of n/c2 versus C2 have slopes quite different from zero. In fact, any inquiry into the significance of the second virial coefficient must seek to explain both positive and negative slopes in such plots. The form of the virial expansion suggests that the molecular origin of the second virial coefficient is the pairwise interaction of solute particles-B is the coefficient of the X2 term in Eq. (8.83)-with the higher coefficients arising from the third- or higher-order  [c.553]

Applications. AppHcations of radiometers and thermal imagers range from energy audits of buildings, to airborne crop surveys, to helping firefighters locate people in smoke-filled rooms. The appHcations related to chemical technology primarily deal with process monitoring and plant maintenance. Historically, many of these appHcations have been more fully utilized in other areas, particularly steel (qv) and electronics, but as engineered materials continue to replace metals and as quaHty control needs become more stringent, they are increasingly being adopted in chemical activities. The most obvious plant inspection tasks that radiometers and thermal imagers can be used for involve elevated or reduced temperature processes (see Temperature measurements). A thermal imager simplifies inspection because large areas can be surveyed rapidly and the image is normally much simpler to interpret than multiple point measurements. Abnormal temperature distributions in heat exchangers or air coolers can indicate blocked or constricted pipes. Leakage by a steam trap produces a local hot spot. Thermal inspection of furnaces can reveal poor flame patterns, inefficient combustion, and coking. The outer shells of insulated vessels inspected during operation show hot or cold spots wherever flaws occur in the refractory or insulating linings. The temperature determined at such a spot is a measure of the threat to the outer shell. A second group of appHcations involve detecting the heat produced by malfunctions or incipient failures. Worn bearings produce hot regions in mechanical equipment. Poor contacts in electrolytic ceUs are observable. Stressed transformers, breakers, and other electrical gear radiate at the stress points (81).  [c.204]

Measles, Mumps, Rubella. Live, attenuated vaccines are used for simultaneous or separate immunization against measles, mumps, and mbeUa Hi children from around 15 months of age to puberty. Two doses, one at 12—15 months of age and the second at 4—6 or 11—12 years are recommended Hi the United States.  [c.357]

A second source of difficulty is caused by the unavoidable empty space in recycle reactors. This limits their usefulness in some studies. Homogeneous reactions in the empty gas volume may interfere with heterogeneous catalytic measurements. Transient experiments could reveal much more information on various steps in the reaction mechanism but material in the empty space can obscure sharp changes.  [c.145]

This example (Fig. 2.10) also shows the limitations of the ////COSY experiment first, evaluation, without taking known shifts and possible couplings into account, is not always conclusive because the cross-sectional area of the cross signals may not reveal which specific couplings are involved second, overlapping signals (e.g. Sh = 7.55 and 7.60 in Fig. 2.10) are not separated by ////COSY if the relevant protons couple to one another. If there is sufficient resolution, however, the fine structure of the multiplets may be recognised by the shapes of the diagonal and cross signals, e.g. in Fig. 2.10, at Sh= 7.55 there is a triplet, therefore the resonance at Sh= 7.60 is a doublet (see the shape of the signal on the diagonal at Sh = 7.55-7.60 in Fig. 2.10).  [c.33]

Electrical and dynamic mechanical tests often reveal transition temperatures additional to the glass transition temperature (and in the case of crystalline polymers the crystal melting point). These occur because at temperatures below the glass transition temperature, side chains, and sometimes small segments of the main chain, require less energy for mobility than the main segments associated with the glass transition temperature. Various types of nomenclature are used, one of the most common being to label the transitions a, 3, y, 8 and so on in descending order of temperature, the a-transition normally corresponding to the glass transition temperature. It must be stressed that simply to label a transition as a p-transition does not imply any particular type of mechanism and the mechanism for a -transition in one polymer could correspond to a y-transition in a second polymer.  [c.47]

Kinetic studies of the reaction of alcohols with acyl chlorides in polar solvents in the absence of basic catalysts generally reveal terms both first-order and second-order in alcohol. Transition states in which the second alcohol molecule acts as a proton acceptor have been proposed  [c.486]

Below — 140°C, the EPR spectrum observed was that of the cyclopropylmethyl radical. If the photolysis was done above — 140°C, however, the spectmm of a second species was seen, and above — 100°C, this was the only spectmm observed. This second spectmm could be shown to be that of the 3-butenyl radical. This study also established that the 3-butenyl radical did not revert to the cyclopropylmethyl radical on being cooled back to — 140°C. The conclusion is that the ring opening of the cyclopropyl radical is a very facile process and that the lifetime of the cyclopropyl radical above — 100°C is very short. Even though the equilibrium favors the 3-butenyl radical, the reversible ring closure can be detected by isotopic labeling experiments, which reveal the occurrence of deuterium migration  [c.669]

Disciplined methods are those proven methods that employ fundamental principles to reveal information. There are two different approaches to problem solving. The first is used when data is available, as is the case when dealing with nonconformities. The second approach is when not all the data needed is available.  [c.458]

Kinetic studies of these reactions reveal that they follow a second-order rate law Rate = [Aryl halide] [Nucleophile]  [c.977]

FIGURE 5.26 Disulfide bridges typically are cleaved prior to determining the primary structure of a polypeptide. Consequently, the positions of disulfide links are not obvious from the sequence data. To determine their location, a sample of the polypeptide with intact S—S bonds can be fragmented and the sites of any disulfides can be elucidated from fragments that remain linked. Diagonal electrophoresis is a technique for identifying such fragments, (a) A protein digest in which any disulfide bonds remain intact and link their respective Cys-con-taining peptides is streaked along the edge of a filter paper and (b) subjected to electrophoresis. (c) A strip cut from the edge of the paper is then exposed to performic acid fumes to oxidize any disulfide bridges, (d) Then the paper strip is attached to a new filter paper so that a second electrophoresis can be run in a direction perpendicular to the first, (e) Peptides devoid of disulfides experience no mobility change, and thus their pattern of migration defines a diagonal. Peptides that had disulfides migrate off this diagonal and can be easily identified, isolated, and sequenced to reveal the location of cysteic acid residues formerly involved in disulfide bridges.  [c.141]

Nucleic acid hybridization is a commonly employed procedure in molecular biology. First, it can reveal evolutionary relationships. Second, it gives researchers the power to identify specific genes selectively against a vast background of irrelevant genetic material. An appropriately labeled oligo- or polynucleotide, referred to as a probe, is constructed so that its sequence is complementary to a target gene. The probe specifically base pairs with the target gene, allowing identification and subsequent isolation of the gene. Also, the quantitative expression of genes (in terms of the amount of mRNA synthesized) can be assayed by hybridization experiments.  [c.374]

The orbital energies from an RHF calculation may be used for selecting the important orbitals. The highest occupied and lowest unoccupied are usually the most important orbitals to include in the active space. This can be partly be justified by the formula for the second-order perturbation energy correction (Section 4.8.1), the smaller the orbital energy difference, the larger the contribution to the correlation energy. Using RHF orbital energies for selecting the active space may be problematic in two situations. The first is when extended basis sets are used, where there will be many virtual orbitals with low energies, and the exact order is more or less accidental. Furthermore, RHF virtual orbitals basicly describe electron attachment (via Koopmans theorem. Section 3.4), and are therefore not particular well suited for describing electron correlation. An inspection of the form of the orbitals may reveal which to chose, they should be the ones which resemble the  [c.120]

The success of FMO theory is not because the neglected terms in the second-order perturbation expansion (eq. (15.1)) are especially small an actual calculation will reveal that they completely swamp the HOMO-LUMO contribution. The deeper reason is that the shapes of the HOMO and LUMO resemble features in the total electron density, which determines the reactivity.  [c.351]

When the austenite is ordered with the B2 structure and the martensite is of the close packed type the latter is based on a face centred tetragonal (fct) lattice with an LIq type ordering as a direct result of the diffusionless character. The transformation can be described by different geometrical constructions, one being a simple tetragonal distortion during which one of the bcc cubic axes is elongated, the other two being equally compressed. Alternatively, the combination of a homogeneous shear of the (112) planes in the [i 11] direction together with a specific shear or shuffle of the (110) planes in the [liO] direction can also yield the same martensite structure". The first one is necessary to obtain close packed planes in the martensite while the second one arranges these planes in a given stacking and thus corresponds with the possibility of multiple twinning or stacking faults on these planes. Shearing in the same direction for every (110) plane yields an ABC stacking while opposite shears result in an ABAB stacking and are sometimes called shuffles. In view of the close packed nature of the final basal planes the resulting lattice is described in fct rather than body centred tetragonal (bet) terms. By using the latter approach the distortions can be correlated with physical features of the austenite such as the lattice softening of the C = (Ci i - C12) / 2 shear modulus or the overall low energy of the TA2[110] phonon branch. Both are related with the homogeneous (110)[110] shear and display remarkable anomalous behaviour close to but clearly above the transformation temperature. A typical precursor feature of the phonon dispersion curve is a dip at a given frequency, correlated with a shuffle of the corresponding wavelength, whereas for the elastic constants a strong increase in anisotropy is noted. At the same time elastic scattering can reveal [110] diffuse intensity around the Bragg peaks or reflections, sometimes even with a distinct satellite. The extinction conditions, corrected for double diffraction in the case of dynamic scattering, indicate that this diffuse intensity with its possible satellite correspond with (110)[li0] transverse displacement waves. The tweed patterns in conventional two-beam transmission electron microscopy (TEM) indicate that these displacement waves have a static character. The effects of the satellite can only be visualised by using high resolution TEM (HRTEM) and will be discussed further on.  [c.323]

A few years after Regulation XV was implemented, when medium-sized businesses (100-250 employees) came under the regulatoi y requirements, the business community began exerting significantly increased political pressure on the South Coast Air Quality Management District (SCAQMD) to repeal the regulation, and took their case directly to Congress. On December 23, 1995, Congress amended Section 182(d)(1)(b) of the Clean Air Act. The new language allowed air quality planning agencies to opt nut of the required employer-based programs.  [c.1146]

At this point a brief comment on the justification of testing the Gibbs or any other thermodynamically derived relationship is in order. First, it might be said that such activity is foolish because it amounts to an exhibition of scepticism of the validity of the laws of thermodynamics themselves, and surely they are no longer in doubt This is justifiable criticism in some specific instances but, in general, we feel it is not. The laws of thermodynamics are phenomenological laws about observable or operationally defined quantities, and where one of the more subtle deductions from these laws is involved it may not always be clear just what the operational definition of a given variable really is. This question comes up in connection with contact angles and the meaning of surface tensions of solid interfaces (see Section X-6). Second, thermodynamic derivations can involve the exercise of logic at a very rigorous level, and it is entirely possible for nqnsequiturs to creep in, which escape attention until an experimental disagreement forces a reexamination. Finally, the testing of a thermodynamic relationship may reveal unsuspected complexities in a system. Thus, referring to the preceding subsection, it took experiment to determine that the surface active species of Aerosol OTN was HX nither than (Na, X ) and that, Eq. III-93 was the appropriate form of the Gibbs equa-/fion to use. The difficulties in confirming the Kelvin equation for the case of liquids in capillaries have led people to consider various possible complexities (see Section III-1C).  [c.79]

The complexity of polymer systems prevents tlieir simulation in full stmctural and dynamical detail [66], First, tire relevant length scales of polymer systems range from about 1 A, tire lengtli of a bond, to hundreds of Angstroms, tire size of tire chains. Second, tire time scale important to polymer systems covers more tlian ten orders of magnitude. Consequently, a trade-off between tire level of stmctural detail, tire size of tire system, and tire time scale of tire processes under study has to be made. On one extreme, atomistically detailed models [, provide tire specific behaviour of a particular polymer, but tire dynamics can be followed up to a few nanoseconds only 1671. On tire otlier extreme, coarse-grained models pennit tire study of dynamics in tire melt and of phase separation processes, but tliey reveal only universal features, tire particular behaviour of different polymers is lost [66]. Wlren none of tire extreme models suit, it may be possible to identify tire elementary move of Monte Carlo simulations witli a relative time step, tliis metliod is known under tire name dynamical Monte Carlo simulation [66]. Alternatively, tire observation window of a molecular dynamics simulation can be shifted to longer times by freezing tire fastest degrees of freedom and increasing the duration of tire integration time step. For example, in so-called constrained molecular dynamics simulations tire bond lengtlis and the bond angles are kept fixed, so tliat tire integration time step can be chosen one or two orders of magnitude longer tlian 1 fs, tire time step typically used in unconstrained atomistic molecular dynamics simulations [67].  [c.2538]

The practice of estabHshing empirical equations has provided useflil information, but also exhibits some deficiencies. Eor example, a single spray parameter, such as may not be the only parameter that characterizes the performance of a spray system. The effect of cross-correlations or interactions between variables has received scant attention. Using the approach of varying one parameter at a time to develop correlations cannot completely reveal the tme physics of compHcated spray phenomena. Hence, methods employing the statistical design of experiments must be utilized to investigate multiple factors simultaneously.  [c.333]

Balancing these crystallization steps to maximize the yield and maintain high product quaUty is a significant operational challenge, especially when confronted with changing thick juice quaUty, ie, color, purity, and pH stabiUty (Table 1). These values reveal the critical dependence of performance on the quahty of the thick juice and, by inference, on the nature of the beets. Calculations have assumed the same yield for each of the boilings. The higher nonsucrose loading has reduced the final yield by 5% for the low purity thick juice. For the same 100 kg of sugar entering crystallization, each stage of the low purity scenario has to handle 40—50% more material because of increased concentrations of returned sugar from the second and third stages. Because the process is controlled by kinetics, either pan yields must be sacrificed or overall throughput must be reduced either choice has cosdy results. Low purity juices tend to be less stable with respect to color, pH, and calcium precipitation, and the choice is always between bad and worse.  [c.28]

In the case of gases, flow lines can be revealed through the use of smoke trac-es or the addition of a hghtweight powder such as balsa dust to the stream. One of the best smoke generators is the reac-tion of titanium tetrachloride with moisture in the air. A woodsmoke-generation system is described by Yu, Sparrow, and Eckert [Int. J. Heat Mass Transfer, 15, 557-558 (1972)]. Tufts of wool or nylon attached at one end to a sohd surface can be used to reveal flow phenomena in the vicinity of the surface. Optical methods commonly employed depend upon changes in the refractive index resulting from the presence of heated wires or secondaiy streams in the flow field or upon changes in density in the primaiy gas as a result of compressibility effects. The three common techniques are the shadowgraph, the schlieren, and the interferometer. All three theoretically can give quantitative information on the velocity profiles in a two-dimensional system, but in practice only the interferometer is commonly so used. The optical methods are described by Ladenburg et al. (op. cit., pp. 3-108). For additional information on other methods, see Goldstein, Modern Developments in Fluid Dynamics, vol. 1, London, 1938, pp. 280-296.  [c.889]

Under normal incidence high resolution images of ropes reveal usually sets of parallel lines corresponding to the parallel tubes. Occasionally a small segment of a rope is strongly bent making it possible to observe locally a rope along its length axis (Fig. 7). Such images show that the SWCNT are arranged on a hexagonal lattice. Due to the deformation resulting from van der Waals attraction the tubes in the lattice acquire an hexagonal cross section [14,15].  [c.18]

Fuithennore, kinetic studies reveal that electrophilic addition of hydrogen halides to alkynes follows a rate law that is third-order overall and second-order in hydrogen halide.  [c.378]

In the solid state the eight-membered rings 12.23 adopt boat conformations with the phenyl groups (attached to sulfur) in equatorial positions. Density functional theory calculations for the model system H2C2N4S2H2 reveal that the observed C2V geometry is a result of a second-order Jahn-Teller distortion of the planar (D2a) structure. The chair conformer is only ca. 2.3 kcal mob higher in energy than the boat conformer. The sixteen-membered ring 12.24 has a cradle-like structure with S4 symmetry. A fascinating property of the eight-membered rings is their solid-state photoisomerization to the purple diazenes PhSN=C(Ar)N=NC(Ar)=NSPh (Scheme 12.4). " For example, yellow crystals of 12.23 in a glass vial exposed to laboratory light become coated on the surface with purple crystals of the corresponding diazene within a few days. This transformation is also observed upon heating 12.23 to ca. 190°C. A combination of kinetic measurements and DFT calculations show that it is a first order process, which is thermally symmetry forbidden, but photochemically allowed. " The sixteen-membered ring 12.24 is unaffected by photolysis.  [c.251]

This separation technique uses isoelectric focusing in one dimension and SDS-PAGE in the second dimension to resolve protein mixtures. The proteins in a mixture are first separated according to pi by isoelectric focusing in a polyacrylamide gel in a tube. The gel is then removed and laid along the top of an SDS-PAGE slab, and the proteins are electrophoresed into the SDS polyacrylamide gel, where they are separated according to size (Eigure 5A.5). The gel slab can then be stained to reveal the locations of the individual proteins. Using this powerful technique, researchers have the potential to visualize and construct catalogs of virtually all the proteins present in particular cell types. The ExPASy Molecular Biology World Wide Web server of the University of Geneva (located at URL http //expasy.hcuge.ch/) provides access to a two-dimensional polyacrylamide gel electrophoresis database named SWISS-2DPAGE. This database contains information on proteins, identified as spots on two-dimensional electrophoresis gels, from many different cell and tissue types.  [c.155]

This beautiful article maintains its position in the front rank of preparations for perfumery, and will probably remain without a rival among artificial perfumes for some time to come. Although the violet scent has long been a favourite perfume, its popularity has doubled through the invention of ionone, and it is not too much to say that the introduction of that body alone has made it possible to produce a perfect extract. Some of the leading European perfumers produce violet extracts which may be recommended as examples of excellence, and which have deservedly become commercial articles of the first importance. The inventors of ionone have earned the gratitude of the entire perfumery industry, and may be congratulated in turn upon the remarkable success of their invention.  [c.220]

According to Presnjakow the best composition of the AlZn alloy, when the superplastic deformation is to be considered, is eutectoidal because the amounts of both phases (a and P) are equal, which is particularly advantageous for the grain boundary sliding to occur. In that case grain size (which should be of about 1 pm) and shape of the grains which should be equiaxed (globular), are very important. It has been stated that superplastic deformation does not only produce new texture types but also weakens the existing one, especially in the zinc phase. Deformation at high strain rates (the third range) generates textures in both A1 and Zn phases. Within the second range of strain rates, dislocation slip is concentrated in external parts of grains (in Kornmantel) whose interior remains free of dislocations. Within the third range, dislocation nets and low-angle-boundaries appear in the whole grain. The results of works" " reveal that superplastic deformation leds to the formation of texture components, which are stable during the crystallographic slip. But, as Lee has stated, the final texture in the sample deformed superplastically ( at 533K and strain rate 10 -10 s ) was affected not only by the crystallographic slip but also by the strain induced recrystallisation and continuous recovery.  [c.405]

The presence of second phases also implies partitioning of the elements with consequent alloying element segregation. In some martensitic steels there can be retained austenite following cooling from the hardering temperature while conversely, with some austenitic steels, there can be some martensite present in the softened state or, more commonly, induced by cold deformation. Since the austenite-martensite transformation is rapid and occurs at low temperatures, there is little chance of alloying element segregation while the crystallographic state itself has little effect on corrosion resistance. Thus the presence of austenite in martensite and vice versa has little practical effect, although substantial acid attack can reveal a difference. When austenite is formed in a martensitic steel from prolonged heating below the temperature it does have a different composition from the now tempered martensite matrix. This situation can apply with the precipitation hardening grades when overaged, but the practical effect on corrosion resistance is very small. Austenite may form in some, but not all, ferrite steels (depending upon composition) during high-temperature heat treatment. In the case of the less highly alloyed types (e.g. 430SI7) this transforms to martensite on cooling, while with the more highly alloyed types it remains as austenite. In both cases there is reversion to ferrite and homogenisation with the correct heat treatment but even if such treatment is omitted, the effect on corrosion resistance is small.  [c.537]


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