Determination of the Adsorbed Quantities of Surfactants by IR-Spectroscopy

Direct determination of the adsorbed amounts of surfactants on AgI by IR-spectroscopy is described. The adsorbed quantities are determined from the relationship between the intensities of the characteristic bands in IR-spectra of standard samples and the samples with adsorbed surfactants. The samples for IR-measurements are in the form of patterns consisting of AgI separated from the systems. The quantities of adsorbed sodium n-dodecyl sulphate, laurylamine nitrate and triton-X-305 are determined

Taming Atomic Defects for Quantum Functions

Single atoms provide an ideal system for utilizing fundamental quantum functions. Their electrons have well-defined energy levels and spin properties. Even more importantly, for a given isotope -- say, $^{12}$C -- all the atoms are identical. This creates a perfect uniformity that is impossible to achieve in macroscopic-size quantum systems. However, herding individual atoms is a very difficult task that requires trapping them with magnetic or optical means and cooling them down to temperatures in the nanokelvin range. On the other hand, the counterpart of single atoms -- the single defects -- may be as good as atom-based quantum systems if not better. These defects, also referred as quantum defects, possess the favorable energy, spin, and uniformity properties of single atoms and remain in their place without the help of precisely tuned lasers. While the number of usable isotopes is set, the combinations of defects and their host material are practically limitless, giving us the flexibility to create precisely designed and controlled quantum systems. Furthermore, as we tame these defects for the quantum world, we bring about transformative opportunities to the classical world in forms such as ultradense electronic devices and precise manufacturing. In this research insight, we introduce some of our recent work on precisely controlled creation and manipulation of individual defects with a scanning tunneling microscope (STM). We also discuss possible pathways for utilizing these capabilities for the development of novel systems for Quantum Information Science (QIS) applications such as quantum information processing and ultrasensitive sensors

Investigations of Tll Suspensions

Thallous iodide suspensions were obtained by direct mixing of TlN03 and Na! solutions. The amount of TH was kept constant in the systems, while the concentrations of Na! (in excess), laurylamine nitrate (LAN) or myristylamine nitrate (MAN) were varied. Tyndallometric values were recorded as the function of Na!, LAN, and MAN concentrations respectively, for suspensions aged for various times. Particle sizes of differently aged TH in \u27Suspensions containing Na! and Eu(N03)a in solution were determined. Tyndal.:. lometry and electronmicroscopy showed fast particle growth of TH in suspension. After about 10 minutes the TH particle grew up to 1.3 μ. The zero point of charge, determined by microelectrophoresis, was attained at 0.001-0.005 M Na! and 0.0001-0.0005 M LAN depending on the conditions under which the system had been prepared. The results of radiometrically recorded adsorption- desorption equilibria show a constant increase of the adsorption capacity as the electrolyte concentration increases

Investigations of Tll Suspensions

Thallous iodide suspensions were obtained by direct mixing of TlN03 and Na! solutions. The amount of TH was kept constant in the systems, while the concentrations of Na! (in excess), laurylamine nitrate (LAN) or myristylamine nitrate (MAN) were varied. Tyndallometric values were recorded as the function of Na!, LAN, and MAN concentrations respectively, for suspensions aged for various times. Particle sizes of differently aged TH in \u27Suspensions containing Na! and Eu(N03)a in solution were determined. Tyndal.:. lometry and electronmicroscopy showed fast particle growth of TH in suspension. After about 10 minutes the TH particle grew up to 1.3 μ. The zero point of charge, determined by microelectrophoresis, was attained at 0.001-0.005 M Na! and 0.0001-0.0005 M LAN depending on the conditions under which the system had been prepared. The results of radiometrically recorded adsorption- desorption equilibria show a constant increase of the adsorption capacity as the electrolyte concentration increases

New evidence for important lake-level changes in Lake Baikal during the Last Glaciation

In recent years, a number of estimates have been proposed of fluctuations of the Baikal lake level caused by climate changes. They were mainly based on the interpretation of reflection seismic data from the Selenga delta area (eastern coast of Lake Baikal). These estimates range between 2 m [Colman, 1998] and 600 m [Romashkin et al., 1997]. Better-constrained values of lake-level changes during the last 100 ky were presented by Urabe et al. [2004]. According to their reflection seismic data from the Selenga delta area, the level of Lake Baikal was significantly lower than the present-day level during the two last cold stages (i.e. -45 m during MIS2 and -73 m during MIS4). To precise and verify these values, we carried out an additional high-resolution reflection seismic study in the area of Olkhon Gate (western shore of Lake Baikal). The maximum water depth in this area does not exceed 40 m. The seismic data were collected using two different types of seismic sources: i) a multi-electrode CENTIPEDE sparker with a frequency range of 350-1400 Hz, and ii) the “Sonic-2” seismic system with a frequency range of 2-5 kHz. They allow investigation of the sedimentary record with a resolution of about 1 m (to 300 m depth) and 15-20 cm (to 30 m depth), respectively.Interpretation of these new data allowed distinguishing several seismic units separated by unconformities (erosion surfaces) in the upper part of the seismic profiles. These unconformities could be traced across the entire study area. The uppermost two erosion surfaces are more sharply defined. In the deepest parts of the channel (at 37-40 m water depth) the uppermost unconformity occurs at 5-10 ms below the lake floor, and the second unconformity at 15-20 ms below the lake floor. Both unconformities are interpreted as subaerial erosion surfaces and thus mark a lowstand of the lake level during a prolonged time. For calculation of the thickness of these two units, we used the acoustic logging data from the BDP-98 borehole [BDP Members, 2000]. According these data p-wave velocities vary from 1.6 to 1.8 km/s. The thickness of our upper two seismic units can thus be converted to 4-8 m and 12-16 m, respectively. This implies that the uppermost unconformity occurs at 41-48 m, and the second unconformity at 52-64 m below present-day lake level, which is approximately at the same depth as the two unconformities in the Selenga delta area that were studied by Urabe et al. [2004] and attributed with the MIS2 and MIS4 cold periods, respectively.Our new data thus support the growing amount of evidence of a lowering of the Lake Baikal water level by 40-65 m during glacial/cold periods. The lowstands are probably caused by water redistribution in the Lake Baikal watershed due to climate changes (i.e. glaciation and atmospheric circulation). These data also allow making quantitative assessments of water balance and paleoclimate parameters in the past

Determining the structure of a large tilted block between two major boundary faults in a continental rift (central Lake Baikal): a reflection seismic study

Between the major boundary faults of the central part of Lake Baikal (ie. the Ol’khon fault and the Primorsky fault), a structurally complex tilted area exists that is strongly influenced by the interaction between these two faults. This area, that is about 30 kilometer wide and a 100 kilometers long, consists of three main parts: Pri-Ol’khon, Ol’khon-island and the submerged Maloe More depression. It is believed that the area formed by the gradual propagation of the Primorsky fault in a southeast direction towards the Ol’khon fault.During the summer of 2001 a large amount of high resolution reflection seismic profiles were shot in Maloe More (>600 km), that could be used to get a better insight in the structural development of the area, and in the geometry of its different sub-blocks and basins. In a first stage we have investigated the morphology of the basement underneath the sedimentary cover, and we determined which structures were fault related and which not. Age constraints on the subsequent evolution came from the correlation of the sedimentary units in Maloe More with deposits on Ol’khon-island, and with data from the long BDP-cores in a nearby area (Academician Ridge).The depth of the basement gradually increases from the southwest towards the northeast, and its morphology is characterised by several ridge structures and faults that strike at high-angle to the main faults. Several of these ridges border basins that contain relatively old sediments (Miocene age; Unit A) later overlain by younger units. Therefore the main basement structures of the Maloe More area should be older than the general believed age for the southward propagation of the Primorsky fault (1 Ma according to earlier models). Moreover the occurrence of relatively thick deposits of unit A in the southwestern extremity of Maloe More and in Ol’khon-gate contradicts the idea that these parts of the area are the youngest, being submerged only recently.Instead, older (isolated) sedimentary traps and lacustrine environments must have existed in this area. Faulting in the younger sediments however shows that the presentday activity of the major boundary faults, still has a pronounced effect on the local structure between them. Some of the formed basins are still determined by displacements on the older structures.For this study we have tried to determine the evolution of the Maloe More area, based on its interpreted structure and the relation with overlying sedimentary deposits, and we have tried to link our observations with existing models for the development of the Primorsky and Ol’khon faults

Propagation of the Primorsky Fault in the central part of Lake Baikal and the evolution of Maloe More

The Primorsky Fault is one of the two major western boundary faults in the central part of Lake Baikal. According to the existing fault growth model (e.g. Agar and Klitgord, 1995), this fault has propagated gradually in a southward direction. During this propagation, the Primorsky Fault has cut through the footwall of the Ol’khon Fault, which is the other major boundary fault 35–40km to the south-east. This propagation has controlled the submergence of the Ol’khon Region which forms a large tilted block between both faults.Based on the interpretation of high-resolution reflection seismic profiles of the submerged part of the Ol’khon Region (ie. Maloe More), different depocentres have been identified in the hanging-wall region of the Primorsky Fault. These depocentres correspond to small basins that are separated from each other by distinct basement ridges, with an orientation that strikes almost perpendicularly to the Primorsky Fault. The occurrence of the oldest sedimentary deposits (Unit A, Miocene age) in depocentres in the southern part of Maloe More, indicates that old sedimentary traps and lacustrine environments must have existed in the area. This finding contradicts the existing growth model for the Primorsky Fault, which assumes that only a recent (ca. 1Ma) and gradual propagation of the fault is responsible for the increasing subsidence in Maloe More. In the different sub-basins, younger sediments (Unit B, Upper Pliocene) overlie the deposits of Unit A. Nevertheless, the upper parts of Unit B are also present on the different basement ridges. The thickness of Unit B is on the northeastern ridges in Maloe More considerably greater than on those more to the south-west, indicating that they have been submerged for a longer time. Careful investigation of a RESURS satellite image of the area has revealed a possible segmentation of the Primorsky Fault, with segment boundaries occurring at the location of the different basement ridges in Maloe More.We believe that the growth of the Primorsky Fault can therefore be described in two different stages. A first stage, during the deposition of Unit A, was characterised by the evolution of 5 different (isolated) segments that defined small basins in Maloe More. The observed basement ridges corresponded at that time to intrabasin highs that resulted from the displacement deficit between the different fault segments. Increasing extension lead to the further growth of the segments, causing a final linkage between them. This linkage marks the onset of a second stage, which was achieved during the deposition of Unit B. Linkage between fault segments caused a displacement increase (mainly at the former location of the segment boundaries), resulting in the submergence of the basement ridge. Seen the thicker deposits of Unit B on the northeastern ridges in Maloe More, we believe that the segment linkage was first established between the northernmost fault segments of the Primorsky Fault. Subsequent linkages between other segments more to the south, and the associated post-linkage displacement increases, caused the further submergence of Maloe More towards the southwest in later stages

Going Beyond Silver in Ethylene Epoxidation with First-Principles Catalyst Screening

Ethylene epoxidation is industrially and commercially one of the most important selective oxidations. Silver catalysts have been state-of-the-art for decades, their efficiency steadily improving with empirical discoveries of dopants and co-catalysts. Herein, we perform a computational screening of the metals in the periodic table, identify prospective superior catalysts and experimentally demonstrate that Ag/CuPb, Ag/CuCd and Ag/CuTl outperform the pure-Ag catalysts, while they still confer an easily scalable synthesis protocol. Furthermore, we show that to harness the potential of computationally-led discovery of catalysts fully, it is essential to include the relevant in situ conditions e.g., surface oxidation, parasitic side reactions and ethylene epoxide decomposition, as neglecting such effects leads to erroneous predictions. We combine ab initio calculations, scaling relations, and rigorous reactor microkinetic modelling, which goes beyond conventional simplified steady-state or rate-determining modelling on immutable catalyst surfaces. The modelling insights have enabled us to both synthesise novel catalysts and theoretically understand experimental findings, thus, bridging the gap between first-principles simulations and industrial applications. We show that the computational catalyst design can be easily extended to include larger reaction networks and other effects, such as surface oxidations. The feasibility was confirmed by experimental agreement

Scaled physical models of continental rifting: application to the Baikal Rift Zone

Scaled physical models constructed with dry sand layers have proven to be a useful tool for the simulation of the structural patterns that are commonly observed in natural rift systems. With this study we have tried to simulate the evolution of the Baikal Rift Zone as to get better insight in the importance of some of the processes controlling its development. For this purpose, models have been constructed with different baseplate geometries. These models allowed us to observe the possible basement controls on the present-day fault structures in the Baikal Rift Zone.Baseplates having similar shapes as the Siberian Craton caused in the models the development of the stepwise fault deflection that is characteristic for the western border fault system of Lake Baikal. During the initial evolution of the modelled faults, several relay zones were formed between isolated fault segments. Such relay zones are also common in the border fault system of Lake Baikal. In later stages of the modelling, further extension lead to the linkage between fault segments, causing the eventual disappearance of the different relay zones.The development of the models was continuously monitored using digital photographs. Animating the sequence of these photographs allowed to carefully study the kinematic evolution of the experiments. After certain amounts of extension (usually 1 or 2cm) the different basins that had formed in the models were filled with syn-kinematic sand layers. Completed models have subsequently been impregnated and sectioned either vertically or horizontally in 1cm intervals. This technique reveals the internal geometry of the formed fault structures. 3D reconstructions of the models have been produced by digitising certain reference levels on the different crosssections.Such 3D images clearly illustrate the variations in fault displacements in the different parts of the models. Moreover, 3-dimensional representations of the experiments can easily be compared with the available digital terrain models of the Baikal Rift Zone, to test the validity of the modelling results.In this study we have examined in detail the kinematic evolution and the growth of faults in different sandbox experiments, and we have compared our observations with structural interpretations that have already been made for the Baikal Rift Zone

Sandbox simulations of relay ramp evolution

The interaction between two offset overlapping normal faults is characterised by the presence of a relay ramp. In order to investigate the way these structures develop, sandbox experiments were carried out. To simulate the brittle crust, we used dry quartz sand that was extended by means of a rubber sheet located at its base.We imposed the initial configuration of the two interacting normal faults by placing silicone bars at the base of the sand-pack, above the rubber sheet. These, under extension, generated a velocity discontinuity responsible for the development of the normal faults, which later interacted and grew further within the sand package. By varying the initial configuration of the silicone bars, we could easily vary the spacing (distance) between the segments, their overlap, their length and their orientation, and test the influence of these parameters on the development of the ramp between the segments. The modeled faults had aspect ratio’s varying between 2.5 and 5.The relay structures in the experiments were characterised by birth, growth and decay. Birth of a relay ramp marked the onset of interaction and was inferred when a tilt of the sand surface could be observed between the two overlapping faults. Growth was characterised by the propagation of the two interacting faults, increasing the distance of overlap and the tilting of the sand layers. During this growth stage often the deflection of one of the fault traces could be observed. Decay occurred when the two initially isolated faults eventually got connected with each other and the ramp breached.A large part of the relay ramps that were formed in the models were breached — or were getting breached — before the final amount of extension was reached (ß ˜ 20%). For 55% of these ramps it was the hanging-wall fault that propagated towards the footwall fault, for 27% the footwall fault linked up with the hanging-wall fault, and for 18% of these breached ramps, a new fault developed that cross-cut the ramp. The new fault developed only in those cases where the original spacing of the faults was very small compared to their length. An experimental relation between the overlap and spacing of two segments was also determined and compared with earlier theoretical work.Finally, relay ramp evolution in the experiments was also characterised sometimes by several minor-order features which are not commonly observed in natural examples, such as: the further propagation of the fault tips after breaching, an increased displacement gradient just outside the relay ramp instead of inside, etc..