Boundary anomalies

The moving boundary method is usually complicated by small differences between the ascending and descending boundaries in the two arms of the U-tube. These boundary anomalies result from differences in the conductivity (and, therefore, the potential gradient) at each boundary. They can be minimised by working with low protein concentrations. 

The moving boundary method for investigating electrophoresis has, however, been improved by Tiselius to the extent that it has become a powerful tool of investigation, particularly of proteins. Tiselius 10 early work is outlined in his dissertation which includes a valuable discussion of the conditions governing the movement of a boundary. A particularly important experimental detail is that the composition of the solution in which the colloid is suspended should be, as nearly as possible, of the same composition as the solution with which it is in contact at the boundary, otherwise boundary anomalies will be present. These will cause the particles of colloid to move abnormally fast or slow, and may even give rise to additional boundaries. 

Boundary anomalies can also occur in free-boundary electrophoresis, because mobility often depends on the concentration the effects can be large and it is difficult to apply corrections for them. 

The boundary anomalies are least for ions of hi refractive increment relative to their total net electric charge. Thus, protons and other colloidal ions are the most suitable for electrophoresis without pronounced boundary anomalies. 

The buffer ion of the same charge as the protein ion being studied should preferably be a slow one. If no buffer ions slower than the leading (protein) ion are available, both cations and anions in the buffer should be chosen with low mobilities, but it is especially important that the ions of the same charge as the leading ion should be slow (210). The usefulness of slow buffer ions was discovered experimentally by Longs-worth, Shedlovsky, and Macinnes (128), who introduced the diethyl-barbiturate buffers which have since been so widely used. Buffers of tiiis type were useful for several other reasons, but it was also observed that the boundary anomalies were less pronounced with such buffers. 

These general considerations have been verified experimentally by several workers. First, it was shown by Svensson (209) in a study of pig serum at 1 2 dilution that the albumin peak in the ascending limb corresponded to 59% of the total protein at ionic strength 0.10, but only to 43% on addition of 0.37 M sodium chloride. The high ionic strength repressed the boundary anomalies, and the latter value is to be regarded as the correct one. 

The chief advantages of zone electrophoresis as compared to the boundary procedure are (1) It is possible to obtain complete separation into zones of different migration and thus not only a boundary separation of overlapping zones. (2) The so-called boundary anomalies interfere less in zone electrophoresis, and therefore also substances of low molecular weight (e.g., amino acids, peptides, nucleotides) may be studied. In addition, zone electrophoresis (particularly in filter paper strips) requires only minute quantities of material and can be performed with simple and inexpensive equipment. 

It is a remarkable and indeed essential feature of the method that boundary anomalies which may seriously interfere in boundary electrophoresis appear to influence zone electrophoresis to a much smaller degree. A detailed investigation of this in zone electrophoresis has not yet been made, but it appears likely that two factors are of importance in this respect. First the concentration of the migrating substance in each zone is generally lower than in boundary experiments. Second, as the front and the rear of each zone are much closer than in U-tube experiments, diffusion of electrolytes may tend to even out to some degree the local differences in the composition of the medium which are the cause of these anomalies. In any case, as has already been mentioned, zone electrophoresis is applicable to a number of substances of comparatively low molecular weight which are difficult or impossible to study in boundary electrophoresis because of pronounced boundary anomalies (e.g., amino acids, peptides, and nucleotides). 

A problem obviously exists in trying to characterise anomalies in concrete due to the limitations of the individual techniques. Even a simple problem such as measurement of concrete thickness can result in misleading data if complementary measurements are not made In Fig. 7 and 8 the results of Impact Echo and SASW on concrete slabs are shown. The lE-result indicates a reflecting boundary at a depth corresponding to a frequency of transient stress wave reflection of 5.2 KHz. This is equivalent to a depth of 530 mm for a compression wave speed (Cp) of 3000 m/s, or 706 mm if Cp = 4000 m/s. Does the reflection come from a crack, void or back-side of a wall, and what is the true Cp ... 

Fig. 3. (a) General locations of hydrothemial power plants in the continental United States (6). Power is produced directiy from hydrothermal steam indicated by the steam plume at The Geysers in northern California. At all other locations, hot water resources are utilized for power production. In 1993, a hydrothermal power plant also came on line on the island of Hawaii, (b) Location of The Geysers steam-dominated hydrothermal field (D) in Lake and Sonoma counties, within the boundaries of the Cleadake—Geysers thermal anomaly (B). 

Other ductility behavior showed alloys with x = 1-25 and 1.54 whose ductility A (T) jumped near 300°C, passed through a maximum at about 350°C, passed through a maximum at about 350°C, and again decreased at higher test temperatures. Points in Fig. 1 correspond to temperatures of anomalous Au(T) behavior for appropriate hydrogen contents. A clear correlation is observed between the ductility anomalies and special lines in the phase diagram, it i.e., all points fall at the boundaries of the two-phase regions or at the line equidistant from these boundaries. 

The latter represents the boundary condition for the function T at the geoid since it is assumed that the anomaly of the gravitational field, Agf is known at each point. 

Some other anomalies, falling well outside the boundaries of traditional theories, have been experimentally found by Semchikov, Smirnova et al. (see [44-47] and references cited therein) who examined bulk low-conversion copolymerization of about thirty pairs constituted of the commonly encountered vinyl monomers. These anomalies can be listed as follows ... 

The historical background is presented for the asteroid-impact theory that is based on the iridium anomaly found in rocks frm the Cretaceous-Tertiary boundary. Recent measurements of Ir, Pt, and Au abundances from such rocks in Denmark have shown that the element abundance ratios are different from mantle-derived sources and agree with values for chondritic meteorites within one standard deviation of the measurement errors (7-10%). Rare-earth patterns for these rocks are... 

Four different ways of calculating the asteroid diameter all give a value of 10 km and this consistency lends confidence to the asteroid-impact theory. The Ir anomaly was first observed by us in Italian rock. Our theory predicted that the unusually abundant Ir should appear all over the world where the C-T boundary is exposed (intact). Part of the hypothesis was confirmed when the anomalously high Ir abundance was found in the C-T boundary layers in Denmark, northern and south-east Spain, and half-way round the world in New Zealand. Another prediction of the theory is that a component of the clay layer at the C-T boundary would be different in composition from other clays in the same section because it contained a component from the impact site. This prediction was confirmed in measurements of the Italian and Danish sections [1]. 

The Ir anomaly has been observed in uplifted marine sediments in four locations in Italy, two in Spain, and one in New Zealand. It has not been found yet in continental sediments or deep-sea cores. If the asteroid-impact theory is valid, the Ir anomaly should be found wherever the C-T boundary is intact. 

The intensity of the C-T iridium anomaly as a function of geographical location along with the mineralogical and chemical studies of the boundary layers may suggest an impact location when considerably more data are obtained. 

Roughening the surface of a sphere causes the transition to a turbulent boundary layer to occur at a lower value of the Reynolds number. This explains the apparent anomaly that, at certain values of the Reynolds number, the drag will be lower for a sphere with a rough surface than for a similar sphere with a smooth surface. It is for the same reason that golf balls are made with a dimpled surface. 

To the west of this ring-like structure, on the boundary of the area, there are several enrichment local anomalies of Ti around enrichment zones of Zn and Pb. In the Zyryanovsk region all the main deposits, are surrounded by a ring-shaped zone of Ti enrichment of 5-10 km in width The internal part of the area of the ringlike anomaly mainly comprises a depletion zone of about 150 km. ... 

In recent years. Znller and associates University of Maryland) have studied six active volcanoes iAugustine, Mount St. Helens. El Chiehdn. Arcnal. Poas. and Colima) and have found no evidence of lr enrichment. The new Kilauea evidence of volcanic action as an Ir source tends to conflict with that of other researchers who have generally attributed the Ir anomaly to an extraterrestrial source, such as resulting from a cataclysmic meteorite or asteroid impact, notably in connection with (he Cretaceous-Tertiary [K i t boundary layer. 

Brooks, R.R., Reeves, R.D., Yang, X.-H. et al. (1984) Elemental anomalies at the Cretaceous-Tertiary boundary, Woodside Creek, New Zealand. Science, 226(4674), 539-42. 

The atomic mechanism, based on the previously proposed inhomogeneous shear, leading to the formation of twinning and antiphase boundaries in TiNi with the CsCl-type structure is described. The twinning mechanism described herein explains the electrical resistivity anomaly due to incomplete thermal cyclings observed previously in TiNi. This explanation is in keeping, in a qualitative manner, with the "memory effects observed in relation to the electrical resistivity anomaly. 

Lattice dimerization in the course of the spin-Peierls-like transition leads to the appearance of new optically active modes folded from a boundary of the Brillouin zone to its center. Charge ordering results in a dielectric anomaly observable in the far-infrared spectral region. 

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