Disturbed Layer Research Articles

Nematic Phases Created in Binary Mixtures of Smectics A

Abstract It is shown that the forming of nematic mixtures composed uniquely of compounds with the smectic phase A is possible. The nematic phase is created as a result of the weakening of intermolecular attraction forces in the disturbed smectic layers. Many examples are given of binary mixtures in which induction of the nematic phase is observed or an enhancement of the nematic phase at the cost of the smectic phase takes place. The effect of the molecular structure and of the properties of the smecticphase A on its destabilization in a mixture and the creation of the nematic gap between the smectic A regions are discussed. The most characteristic features of the phase diagrams related to the S→I and S→N phase transitions and the accompanying changes of enthalpy of these phase transitions, of density and viscosity are shown in detail by way of example of binary mixtures composed of 5-n-alkyl-2-(4′-isothiocyanatophenyl)-1,3-dioxanes (smectic A1) and 80CB, or 120CB or 12CB (smectic Ad).

Photoeffect under the conditions of dynamical X-ray diffraction

The applications of the external photoeffect excited by an X-ray standing wave to structure studies of crystal subsurface layers are discussed. In experiments conducted with an epitaxial Si film doped with B and Ge, with Ge concentrations ranging from 3.7 × 1019 to 1.5 × 1020 atoms cm-3, a change of phase of the scattering amplitude on the photoemission curve is found. This change is caused by the total surface displacement due to a change in the interplanar spacing in the disturbed layer. The experimental results are compared with accurate theoretical calculations in a bicrystal model. Values for the phase ϕ (0) and degree of amorphization exp [W(0)] on the surface are obtained by least-squares fitting. Universal analytical formulae for the computation of functions describing electron transport and the escape depth of electrons in a crystal are suggested. The potentialities of the depth-selective analysis of X-ray standing waves are analysed. The theoretical foundations of the secondary-radiation yield under the conditions of multiple diffraction are developed. A direct observation of an enhanced Borrmann effect in Laue multi-wave diffraction is predicted.

Oxidation of the InSb surface at room temperature

The formation and composition of room-temperature surface oxides on (110) orientated InSb samples was studied with ESCA and AES. The oxides are composed of a mixture of In2O3 and Sb2O5. It is shown that the Sb oxide is Sb2O5 and not Sb2O3, as has been previously generally assumed. Four surface-preparation techniques were compared: free etching, mechanical polishing, chemo-mechanical polishing and anodic oxidation. Chemo-mechanical polishing and free etching yield comparable oxide thicknesses of about 30 AA. Mechanical polishing produces a 100 AA thick disturbed oxide layer. Anodic oxidation allows a choice of the thickness but introduces a strong carbon contamination. The first monocell layer of natural oxide grows very fast, within 80 s a 15 AA layer has formed. Thereafter the oxidation is diffusion controlled and much slower. From renormalisation curves it is concluded that the oxide mainly consists of In2O3 with some Sb2O5. The In oxide stays near the oxide/bulk interface and finally after some 25 days stops further oxidation, while the Sb oxide moves towards the oxide/air interface. In contrast to thermal oxides no Sb layer is found at the oxide/bulk interface.

Expanding behaviour, structural disorder, regular and random irregular interstratification of 2:1 layer-silicates studied by high-resolution images of transmission electron microscopy

AbstractExpanding and non-expanding layers of interstratified clay minerals have been examined by high-resolution transmission electron microscopy. Permanent expansion of swelling layers under the electron beam was achieved by intercalation ofn-alkylammonium ions, especially the octadecylammonium ion. Oriented flakes of clay minerals were prepared by embedding the expanded or non-expanded clay minerals in epoxy resin, followed by centrifugation before hardening of the resin. The minerals were then cut perpendicular to 001 using an ultramicrotome. Crystals ofmacroscopic trioctahedral vermiculitesshow homogeneous interplanar distances of 24 Å after intercalation of octadecylammonium ions. Crystals ofdioctahedral soil vermiculitesoften show a central zone with non-expanding 10 Å layers; the outer zone shows a disturbed layer sequence extensively expanded byn-alkylammonium ions. After embedding in epoxy resin, vermiculites show stable 9·2 Å interplanar spacings but smectites expand to 13 Å.Montmorillonitesof theWyoming typeshow curved stacks of layers. Most of the layer stacks ofmontmorillonitesof theCheto typeare split and disordered aggregates of single layers are formed. Crystals ofillitesandglauconitesare built up of aggregated small stacks of 10 Å layers, the layer stacks consisting of 10 layers. Mostly the boundaries of the layer stacks are parallel to their 001 planes; sometimes low-angle boundaries are found. The dimensions of the layer stacks, ∼ 100 Å thick and some hundreds of Å in plane, are equal to the dimensions of the domains of coherent scattering of X-rays. The border layers between the layer stacks are identical with those 5 to 10% of layers which swell with glycerol or ethylene glycol during X-ray analysis. Some of the layer stacks of illite and glauconite crystals are expanded by octadecylammonium ions within a fortnight. The other stacks show unchanged 10 Å spacings. The different expanding behaviour of different layer stacks reflects the heterogeneity of the layer-charge distribution in the mica clay minerals.K-bentonitesshow the same expanding behaviour as illites and glauconites but the number of layers expanding with octadecylammonium ions is greater in K-bentonites than in illite crystals. Expanded mixed-layered minerals of the illite-smectite type show a different layer stacking sequence from illites. Random irregular stacking of mica layers with expanded layers are recognized rather than coherent stacks of mica layers. The crystals have a stepped morphology, perhaps effected by translations along the 001 plane. After reaction of therectoritefromGarland Countywith octadecylammonium ions, the non-expanded mica layers and the expanded smectite-like layers can be distinguished. The heterogeneity of the interlayer charges of the smectite layers is documented by the formation of alkyl double-layers with 17 Å spacings and alkyl triple-layers with 21 Å spaces in irregular sequence. The ‘rectorite’ from theGoto Mineexpands nearly homogeneously in comparison with the rectorite from Garland County. After reaction with octadecylammonium ions, interplanar spacings of mostly 31 Å are observed but rarely spacings of 27 Å. The smectite layers of thecorrensitefromKaubenheimare expanded by tetradecyl-ammonium ions to 18 Å spacings by formation of alkyl double-layers. A regular 1 : 1 layer structure of 14 Å chlorite layers and expanded 18 Å smectite layers with total spacing of 32 Å can be observed.Muscoviteandpyrophylliteare not expandable byn-alkyl-ammonium ions within a fortnight. However, sporadic layers ofceladonitecrystals are expanded. Generally the 10 Å or 9·2 Å layers extend over the whole crystals of the three minerals. In celadonite crystals, disorder is caused sporadically by interrupted layers or slightly enlarged layer spacings.

An experimental investigation of wall pressure fluctuations beneath nonequilibrium turbulent flows

Abstract : Wall pressure fluctuations beneath a non-equilibrium turbulent boundary layer were studied experimentally. The objective of the investigation was to better understand the process by which turbulent boundary layers flows produce wall pressure fluctuations. The approach was to study the statistics of both the wall pressure field and velocity field for a non-equilibrium turbulent boundary layers, produced by passing a flow over a backward-facing step, and then to identify turbulent structures in the flow that contribute to the source terms of the wall pressure field. Detailed velocity and wall pressure measurements were also obtained for an equilibrium flow to provide a basis of comparison for the perturbed flow results. The wall pressure statistics for the perturbed flow are characterized by the presence of the disturbance layers variables. Hence, the source of the low frequency excess in the wall pressure fluctuations is the disturbance layer. The high frequency wall pressures were found to scale on inner variables, and as such, recovered to an equilibrium flow condition quite rapidly. This places the perturbed source of high frequency wall pressures in the inner layer of the boundary layer.

Topography of etched rhombohedral faces of quartz crystals: evidence for orientation effects

A study has been made of the rate at which the rhombohedral faces of a natural quartz crystal are etched in a concentrated ammonium bifluoride solution. The thickness of the disturbed surface layer created by an initial mechanical lapping is estimated from rate data. The etching rate as well as this thickness are found to be sensitive to natural face orientation. The changes in the surface texture of the rhombohedral faces with repeated chemical etchings are investigated. The variation in the roughness parameters with the average depth of etch shows both directional and orientation effects. The chemical attack results in the formation of stable etch figures characteristic to the orientation of the surface on which they lie and which enlarge with repeated etchings. finally, schematic etch figures are proposed for the differently oriented rhombohedral faces.

Features of thermals in stable wake and neutral stratifications in the disturbed monsoon boundary layer

Thermals, defined as humidity excesses, seem to exhibit distinct features in the disturbed Indian Monsoon Boundary Layer (BL) depending on whether they occur in the stable wake regions, called S in this study, of tropical squalls, or in the neutral regions of the advancing squalls, called N. The stable S region developed weak but gradually increasing ascending motion in the BL while the N region showed strong upward motion at the top of the surface layer (85 m) decreasing steadily thereafter. Similar differences also appear in the other mean thermal fields such as temperature and humidity.

Fluoride-induced cystic changes in the enamel organ of the rat molar.

Many substances have been found to cause enamel disturbances in toxic doses, and it has been postulated that these disturbances are linked to the formation of sub-ameloblastic cysts. In the present investigation, fluoride-induced sub-ameloblastic cysts in developing rat molars were related to fluoride dose, age of the animals, and the plasma fluoride level. The sub-ameloblastic cysts, which developed predominantly towards the end of the secretory stage of amelogenesis, appeared shortly after fluoride administration and regressed within 3 days. Hypoplasias and internal defects were found in the enamel under the disturbed ameloblast layer. The highest plasma fluoride levels were found in the youngest animals 24 h after injection. The frequency and size of the sub-ameloblastic cysts were clearly related to the fluoride-dose and age of the animal and, subsequently, to the plasma fluoride level.

The surface composition of the vrMn 2T 0.8 systems (T  Mn, Fe, Co, Ni) as determined by Auger electron spectroscopy

The surfaces of the hydrogen-absorbing intermetallic systems vrMn 2T 0.8 (T  Mn, Fe, Co, Ni) were evamined by Auger electron spectroscopy. Comparison of the surface features of the members of the series reveals two trends. The first involved the T Mn surface concentration ratios which varied in the order Fe Mn > Co Mn > Ni Mn . The second trend pertained to the thickness of the disturbed ovide layer; this varied in the order Mn > Fe > Co > Ni, where these four elements represent T in the formula vrMn 2T 0.8. It was found that manganese strongly segregates to the surface for all systems studied. These results are generally similar to those obtained recently for the stoichiometric Laves phase systems ErT 2 and HoT 2 (T  Mn, Fe, Co, Ni). Manganese enrichment at the surface appears to be responsible for the rapid hydrogenation kinetics evhibited by the vrMn 2T 0.8 alloys.

Measurement of depolarization of stratospheric particles by lidar - A case study on the disturbed stratospheric aerosol layer by the volcanic eruption of Mt. El Chichon.

Total depolarization ratio has been used to detect nonspherical particles in the stratosphere. This parameter is effective only when the mixing ratio of the particles is enough high. Particle depolarization ratio (Dp) is compared with the total depolarization ratio (D) on the basis of the lidar measurements made at Nagoya, Japan, during the post-El Chichon period. The comparison suggests that the particle depolarization ratio is more effective than the total depolatization ratio when the mixing ratio is lower than about one.

Photoemission curves obtained in conditions of X-ray grazing-incidence Laue diffraction from crystals with a disturbed surface layer

It has been shown that photoemission curves obtained using the X-ray standing wave technique in grazing-incidence Laue diffraction scheme are essentially more sensitive to structure distortions in surface layers of a crystal as compared to the conventional diffraction scheme in the Bragg geometry. A gas-flow proportional counter with a resolution as small as 16% used as photoelectron energy analyzer allows to establish the presence of disturbed layers with thicknesses ≈ 10 nm and less. Es wird gezeigt, daß die mittels stehender Röntgenwellentechnik im Laue-Beugungsfall bei streifender Inzidenz erhaltenen Photoemissionskurven gegenüber Strukturverzerrungen in den Oberflächenschichten eines Kristalls im Vergleich zum konventionellen Beugungsfall in Bragg-Geometrie wesentlich empfindlicher sind. Ein Gasfluß-Proportionalzähler mit einer Auflösung von 16%, der als Photoelektronenenergieanalysator benutzt wird, erlaubt die Feststellung von gestörten Schichten mit Dicken von ≈ 10 nm und darunter.

The geologic setting of the platiniferous UG-2 chromitite layer on the farm Maandagshoek, eastern Bushveld Complex

The platiniferous UG-2 chromitite layer forms part of the upper chromitite group of the critical zone. On the farm Maandagshoek 254KT in the eastern Bushveld Complex the upper chromitite group is made up of four cyclic units, namely, UG-1, UG-2, UG-3, and UG-3A, each of which consists of a basal chromitite layer with or without olivine, overlain successively by melanorite and norite, and terminated with anorthosite. The UG-2 chromitite layer and its associated basal pegmatoid is found close to the base of the UG-2 cyclic unit. The cyclic units are separated by sharp contacts and have a remarkable persistence along strike and downdip.Whole-rock Cu, total Ni, Pt, and Pd show an upward enrichment from the base of the UG-2 unit, reaching a maximum in the main chromitite layer; they are depleted in the hanging-wall sequence of melanorite. Bulk analyses of the UG-2 chromitite and its enclosing lithologies for Pt, Pd, Ru, Rh, Ir, Au, S, sulfide Ni, Cu, and Co show that the platinum-group elements and base metals are concentrated (1) close to the top and base of the main chromitite layer, (2) in the leader layer, and (3) in minor chromitite lenses and layers both in the footwall pegmatoid and the hanging-wall melanorite. The Pt/(Pt + Pd) and Cu/Ni ratios are low in the footwall pegmatoid and base of the main chromitite layer. Values of these ratios, however, increase upward, with Pt/(Pt + Pd) decreasing at the upper contact of the UG-2 layer.The calculated concentration of platinum-group metals in the sulfide phase in the UG-2 chromitite layer ranges from 3,000 to just under 12,000 ppm. The above determination is primarily controlled by the concentration of S in the layer, with the average precious metal distribution remaining relatively constant. The calculated D (super sulfide liquid) (sub silicate liquid) with the parental liquid values in parentheses are Pt: 52,575 (40 ppb), Pd: 132,940 (16 ppb), Rh: 22,080 (8 ppb), Ir: 730,000 (0.4 ppb), and Au: 2,190 (21 ppb).Evidence of an influx of magma into the eastern lobe of the Bushveld Complex at a level between the upper and middle chromitite groups is indicated by discontinuous and disturbed layers in borehole drilling on Maandagshoek. It is suggested that this magma batch was slightly more enriched in the platinum-group elements in order to produce the increased value of these elements in the UG-2 chromitite layer. It is proposed that preexisting sulfides in the UG-2 chromitite layer collected platinum-group elements from upward-migrating, highly fractionated intercumulus fluids under highly reducing conditions during the early stages of formation of the layer. The relatively large volume of sulfide initially present in the layer was later reduced by volatiles enriched in O 2 passing through the layer, resorbing the sulfides and blowing off SO 2 . The partial resorption of the sulfides accounts for the presence of minor Pt-Fe alloys and the abnormally high partition coefficients of the platinum-group elements in the sulfide liquid of the UG-2 chromitite layer.

Predicting Avian Community Response to Lakeshore Cottage Development

Breeding songbird species were studied in both developed and undeveloped lakeshore habitats of central Ontario. Information is presented for managing lake shorelines for human recreational development without significant loss of wildlife values. The disturbed ground vegetation layer was significantly correlated with a number of habitat variables deemed important in describing avian habitats. Avian species were placed in one of three groups: the ovenbird (Seiurus aurocapillus), an example from the group found primarily in undeveloped habitats; the eastern phoebe (Sayornis phoebe), one of the group found in highly developed habitats; and the veery (Catharus fuscescens), from the group that was not significantly affected by development. These findings are presented in a simple model of breeding bird response to disturbance that can be used to assess the negative impact of cottage development. J. WILDL. MANAGE. 48(4):1239-1247 Human encroachment on undeveloped areas often impacts the plant and animal communities located there. Avian species respond as their breeding habitat is altered or destroyed. Neotropical migrants may be particularly affected by development because not only is their breeding habitat being altered, but wintering grounds are being converted to pasture and farmland (Terborgh 1974). In the last 50 years, many lakes in south-central Ontario have become popular for recreational activity. Cottages have been built along many lakeshores with associated roads and transmission line corridors nearby. Unlike successional sequences, cottage construction tends to impose permanent change in the vegetation and associated environment. Resource managers need information to predict how changes imposed by this development affect wildlife. Robertson and Flood (1980) found an increase in diversity of the songbird community along portions of cottage lakesh re in the nearby Rideau Lakes. Martin (1960) investigated changes in bird populations in relation to forest succession in the Algonquin Park area. James and Wamer (1982) and others have demonstrated that bird species diversity depends on vegetation structure and composition. The mportance of large blocks of unbroken for st was reviewed by Robbins (1979). We have added to these studies to provide resource managers with a tool to predict how future cottage development m y affect bird communities along lakeshores. Songbird populations are notoriously diffic lt to measure, and the populations themselves fluctuate widely. Preston (1960) noted that for 57 breeding species in Ohio, based on 10 years of survey data, nly a out half (28 species) bred every year. James and Wamer (1982) showed that study plots of less than 10 ha often have less than the total species breeding in an area. In our work, based on 2 years of data and small sample plots, we cannot hope to show the long-term comprehensive impact of cottage construction on songbird populations. However a general model of cottage development and the re'Present address: Ontario Ministry of Environment, Box 21, Dorset, Ontario POA 1EO, Canada. 2 Present address: Ontario Ministry of Natural Resources, Cochrane, Ontario, POL 1CO, Canada. J. Wildl. Manage. 48(4):1984 1239 This content downloaded from 157.55.39.70 on Tue, 06 Sep 2016 05:51:31 UTC All use subject to http://about.jstor.org/terms 1240 AVIAN COMMUNITY RESPONSE * Clark et al. suiting impact on the wildlife community is needed to provide planners with guidance in approving or disapproving plans for cottage subdivisions. A concurrent study described the habitat associations of 19 species of breeding birds at varying levels of cottage development and determined that tree density, shrub coverage, conifer composition, and canopy volume were important in describing the habitat associations (Clark et al. 1983). The purpose of this study was to develop a method to predict changes in avian species composition caused by cottage development that could be used to model the impact of habitat disturbance on wildlife commu-

Facies, facies-associations and sediment transport/deposition processes in a late Precambrian upper basin-slope/pro-delta,, Finnmark, N. Norway

Summary The lower Naeringselva Member of the 2.5 to 3.5 km thick Båsnaering Formation varies from 60 to 540 m thick, and is part of the 9 km thick late Precambrian Barents Sea Group cropping out on Varanger Peninsula, north-east Finnmark, N. Norway. It is underlain by a minimum 3.2 km of submarine fan deposits and passes up into delta front and fluvio-deltaic deposits of the Båsnaering Formation. Within the lower Naeringselva Member (LNM) four main facies are recognized: parallel-laminated mudstone; current-rippled siltstone; structureless mudstone, and wave-rippled fine-grained sandstone. Soft sediment deformation was abundant as slide, slump and in situ disturbed layers up to tens of metres thick. Erosional-depositional discordances are evident between packets of beds. Palaeocurrent data, together with a limited number of slide fold readings, suggest a west to south-westerly source area for the submarine fan, upper basin-slope/pro-delta and delta deposits. The stratigraphic position and sedimentology of the LNM suggests that it forms part of an ancient upper basin-slope/pro-delta, with fan deposits on the lower basin-slope. Apart from sporadic storm events visibly affecting the slope, it was below wave-base. Modern analogues for the LNM are the upper part of continental slopes separating fan from delta deposits, as in the Mississippi Delta-Slope-Fan system.

Reply by Author to A. R. Wadia

I WISH to thank A. R. Wadia for his interest and remarks concerning my Note. In general, I am in agreement with the ideas expressed in his Comment, but I should like to add the following discussion and to answer the questions posed. The definition of the Navier-Stokes region used in Ref. 1 is, as Wadia points out, restrictive in that it presupposes that flow reversal does not occur outside of the cavity. If this is true, then addition of the interaction with the third layer—the potential outer flow—is usually sufficient to account for the upstream propagation of disturbances through the subsonic portion of the boundary layer as well as to calculate the correct downstream behavior of the disturbed layer. Such a method was described in Ref. 2 and its use illustrated in Refs. 2 and 3. For the relatively low injection rates into the supersonic boundary layer in Ref. 1 (v/U^ =0.02 for the outer flow of M^ =2.25) the two-layer approach, as well as the simple choice of the rectangular Navier-Stokes region, were found appropriate for the purposes of that paper. The disturbed nature of the boundary layer downstream of the slot is evident nevertheless in the results obtained in Ref. 1. The qualitatively correct behavior of reduced shear downstream of the injection slot, and increased shear downstream of the suction slot, was reproduced. The computed values of the u velocity component is one grid interval above the horizontal wall (which is linked to du/dy at the wall) normalized by the corresponding value of this parameter upstream of the slot are persented in Table 1 for three x steps, starting at the downstream corner, and are intended for qualitative comparison only. It was shown in the Comment that for a subsonic flow with a relatively high rate of injection (v/Ux =0.25) a separation bubble can form downstream of the injection slot. To treat such a flowfield adequately using the interactive method of Refs. 1-4, the Navier-Stokes domain should be extended downstream (and perhaps upstream) of the slot to include at least all the regions of flow reversal, as Wadia recognized. If the incompressible equations are to be retained in the recirculation region and the outer flow is supersonic or highly subsonic so that the incompressibility assumption fails in a significant part of the boundary layer, then the matching region may no longer be specified a priori using a simple, rectangular geometry. Instead, curved matching boundaries, which can evolve as the solution proceeds, are necessary. Such a self-adaptive approach to the construction of the matching region is, at present, beyond the capability of the model, but is a natural subject for further work in extending the method. The vorticity at the two convex corners of the slot was determined along the vertical walls for Navier-Stokes region Slot width

Laser annealing of cadmium sulfide crystals

Cadmium sulfide crystals with a disturbed surface layer about 5 μ thick were annealed by KrF* laser pulses of 10 nsec duration. This improved the crystal structure when the cadmium side was irradiated. The effect was not detectable on the sulfur side. The threshold energy density of the effect was ~0.25 J/cm2.

CULTIVATION AND EVAPORATIVITY EFFECTS ON THE DRYING PATTERNS OF SANDY LOAM SOIL

We conducted laboratory and field experiments to study the influence of the depth of cultivation on (1) the loss of water from and below the disturbed layer, (2) the cumulative evaporation (CE) and time (t) relationship, and (3) the advance of isohydric fronts into soil, under various evaporativity (E0) conditions. PVC cylinders, 10 cm ID and 95 cm long, were filled with air-dry (θ = 1 ± 0.25 g/100 g) sandy loam soil to a bulk density of 1.5 g/cm3]. The columns were wetted from the top with 19 cm of water, allowed to equilibrate for a week, cultivated to depths of 0, 6, and 12 cm, and then subjected to drying under evaporativities of 16 (high), 8 (medium), and 4 (low) mm/ day. Also, we studied the drying of 3 X 3 m field plots cultivated to 0, 5, 10, and 15 cm depths from 8 November to 16 December, 1976, when E0 ranged from 1.8 to 4.3 mm/ day (average 2.8 mm/day). Cultivation reduced evaporation under all the EoS, with the highest reduction under the low E0. The maximum evaporation reduction was obtained after 29 days under high E0 and after 55 days under medium and low Eos. The differences in water loss between the 6− and 12-cm cultivation depths were greater under higher Eo. The relationship CE = Kt0.5] gave an excellent fit for both the 6− and 12-cm cultivation treatments under all Eos. The regression coefficient K increased linearly with E0, and at a given E0 was lower for 12-cm than for 6-cm cultivation. The cultivated layers dried more rapidly than the corresponding depths of uncultivated soil, but the layers below the loosened soil always had more water in cultivated than in uncultivated and in 12-cm than in 6-cm cultivation. The magnitude of differences in soil water across the junction of cultivated layers and the undisturbed soil below was influenced both by cultivation depth and E0. The position of 0.18 and 0.15 cm3]/cm3] isohydric fronts was always deeper in uncultivated than in cultivated soil, except within the loosened zone.

Influence of processing parameters and of natural ageing on the depth of a disturbed layer and on the optical strength of the surface of KCl single crystals

A study was made of the influence of the dimensions of abrasive grains and of the nature of the lubricating and cooling liquid during grinding, annealing, and natural ageing of polished surfaces of KCl single crystals on the depth of a disturbed layer and on the surface optical strength. It was found that the use of processing methods ensuring the minimum depth of the disturbed layer (for example, annealing) made it possible to increase considerably the optical strength compared with that obtained by traditional methods of processing of freshly polished or aged surfaces.

Nonlinear wave interactions in supersonic wind-generated waves

A nonlinear analysis is presented for the case of second-harmonic resonant interactions on the interface of a liquid film and a supersonic gas stream. The analysis takes into account the effects of the gas viscosity and mean profiles. Moreover, the extent of the gas disturbance layer is not restricted to the region in which the mean profiles are linear. Self-sustained oscillations are calculated for low and intermediate liquid Reynolds numbers. The present solution is compared with available experimental data. The predicted and observed wave amplitudes, wavenumbers, and frequencies are in good agreement for intermediate liquid Reynolds numbers. The calculated amplitudes overpredict the observed values by about a factor of three for low liquid Reynolds numbers.

The investigation of disturbed surface layer structure by the external photoeffect under X-ray diffraction conditions

Results of experimental studies of the disturbed surface layer structure in Si crystals after an ion implantation and subsequent annealing as well as epitaxial layers of GaAs and Ge are presented. The method of measuring and calculating theoretically an angular dependence of the external X-ray photoeffect under the diffraction conditions is used for finding the deformation distribution profile in dependence on the distance from the surface. The conclusion is made that the method of comparing the theoretical and experimental curves using the two channels (X-ray reflection and photoemission) simultaneously proved to be a very comfortable and reliable way for the determination of the surface layer structure. Es werden die Ergebnisse von experimentellen Untersuchungen der gestorten Oberflachenschicht-Struktur sowohl in Si-Kristallen nach Ionenimplantation und nachfolgender Temperung als auch von GaAs- und Ge-Epitaxieschichten mitgeteilt. Eine Methode zur Messung und theoretischen Berechnung der Winkelabhangigkeit des auseren Rontgen-Photoeffekts unter Beugungsbedingungen wird zur Bestimmung der Deformationsverteilungsprofile in Abhangigkeit von der Entfernung von der Oberflache benutzt. Es wird festgestellt, das die Methode des Vergleichs der theoretischen und experimentellen Kurven bei gleichzeitiger Benutzung der beiden Kanale (Ront-genref lexion und Photoemission) einen sehr bequemer und zuverlassiger Weg zur Bestimmung der Oberflachenschichtstruktur darstelit.