The Local Compressibility of Liquids near Non-Adsorbing Substrates: A Useful Measure of Solvophobicity and Hydrophobicity?

We investigate the suitability of the local compressibility chi(z) as a measure of the solvophobicity or hydrophobicity of a substrate. Defining the local compressibility as the derivative of the local one-body density w.r.t. the chemical potential at fixed temperature, we use density functional theory (DFT) to calculate chi(z) for a model fluid, close to bulk liquid-gas coexistence, at various planar substrates. These range from a `neutral' substrate with a contact angle of approximately 90 degrees, which favours neither the liquid nor the gas phase, to a very solvophobic, purely repulsive substrate which exhibits complete drying (i.e. contact angle 180 degrees). We find that the maximum in the local compressibility, which occurs within one-two molecular diameters of the substrate, and the integrated quantity chi_ex (the surface excess compressibility, defined below) both increase rapidly as the contact angle increases and the substrate becomes more solvophobic. The local compressibility provides a more pronounced indicator of solvophobicity than the density depletion in the vicinity of the surface which increases only weakly with increasing contact angle. When the fluid is confined in a parallel slit with two identical solvophobic walls, or with competing solvophobic and solvophilic walls, chi(z) close to the solvophobic wall is altered little from that at the single substrate. We connect our results with simulation studies of water near to hydrophobic surfaces exploring the relationship between chi(z) and fluctuations in the local density and between chi_ex and the mean-square fluctuation in the number of adsorbed molecules.Comment: 23 pages, 9 figures, submitted to Journal of Physics: Condensed Matter as a Special Issue Articl

Synthesis and Structures of Fused N-Heterocylic Carbenes and Their Rhodium Complexes

New procedures for the synthesis of N-heterocyclic carbenes with multiple fused rings have been developed utilizing a key ring-closing metathesis step. Rhodium complexes were obtained via the pentafluorophenyl carbene adducts. Solid-state structural behaviors of the new carbene ligands were analyzed via X-ray crystallography

An assessment of the mantle and slab components in the magmas of an oceanic arc volcano: Raoul Volcano, Kermadec arc

Raoul Volcano occupies a simple oceanic subduction setting in the northern part of the Kermadec arc on the Pacific–Australian convergent plate boundary. The primary inputs to the magmatic system that feeds the volcano are a subduction component derived from the subducting old Pacific oceanic lithosphere and its veneer of pelagic sediment, and the overlying peridotitic mantle wedge. Conservative trace elements that are very incompatible during mantle melting are relatively depleted in Raoul lavas indicating a source that has been depleted during an earlier melting event. Major element co-variations indicate magma genesis by 25% near fractional melting of a mantle source that is weakly depleted (2% melt extraction) relative to a fertile MORB source. An important influence on the composition of the mantle component is progressive melt extraction coupled with minimal advection of fresh material into the sub-arc zone followed by melt extraction from a melting column beneath the spreading centre of an adjacent back arc basin. High field strength element and rare earth element systematics indicate involvement of a subduction-related component of constant composition. Two fluid components can be distinguished, one enriched in large ion lithophile elements inferred to be an aqueous fluid that is continuously added to the ascending melt column and the other a less mobile fluid that transfers Th. A homogeneous subduction-related component of constant composition and magnitude arises if the slab-derived flux migrates from the slab–mantle interface to the sub-arc melting column by repeated episodes of amphibole formation and decomposition its composition is then governed by the distribution coefficients of pyroxene and its magnitude by the degree of amphibole saturation of mantle peridotite. The results from Raoul Volcano are comparable to those from other oceanic subduction-related arcs such as South Sandwich and Marianas suggesting that this is a general model for oceanic arcs

An investigation of Hadley and Whitin\u27s heuristic inventory model and adaptive exponential smoothing to respond to changes in the process generating demands

In inventory systems that assume steady state operations, problems arise when real changes in the demand process occur. In the thesis, three adaptive exponential smoothing models, which automatically monitor demand forecasts to ensure that forecasts remain within some control limits, are applied to an inventory system and compared

Bulletin No. 125 - The Chemical Milling and Bake Value of Utah Wheats

The Chemical Department of the Utah Experiment Station, since 1903, has been conducting investigations regarding the value of different wheats grown in the State. The results obtained during the years 1903 to 1906 were published as Bulletin No. 103 of this station. A special investigation in 1910 regarding the influence of the combined harvester on the value of the wheat was conducted and the results obtained issued as Bulletin No. 113. The results reported in the following pages were obtained during the progress of these investigations during the years 1907, 1908, and 1909. The method of milling the samples of wheat are essentially the same as previously reported.* The samples of wheat were all cleaned by the scrubber as indicated in the previous report. The methods of analysis are similar to the ones described in the former bulletins. The determinations for gliadin and glutenin are not reported because considerable energy has been expended on perfecting a better method of determining the gliadin content of the flour. The results of this special investigation have been published by Dr. Greaves. The determination. of the acidity of the flour has also been omitted. Before any valuable information can be obtained from this factor, it is necessary to make a complete study of the methods of determination. Such a study will be taken up at this laboratory. The volumetric method as reported in the former bulletin has no value

Bulletin No. 147 - The Alkali Content of Irrigation Water

In certain irrigated districts the alkali problem is a menace. Any controllable factor which tends to increase the alkali content of the soil should be carefully considered in a successful system of soil management. In this connection the quality of the irrigation water is of great importance; the saline content of water has a marked influence upon the method and quantity to be used for irrigation. The factors which will contribute to an increase or decrease of the alkali content of the water must be clearly understood. The amount of the several kinds of alkali salts added to the soil by large or small applications of water must be clearly understood in order that the farmer may utilize the water supply to the best advantage. A knowledge of the quantity and nature of the alkali salts added to the soil will enable him to more systematically plan his crop rotation since crops vary in their power to resist the action of the several kinds of alkali

Nonproductive Events in Ring-Closing Metathesis Using Ruthenium Catalysts

The relative TONs of productive and nonproductive metathesis reactions of diethyl diallylmalonate are compared for eight different ruthenium-based catalysts. Nonproductive cross metathesis is proposed to involve a chain-carrying ruthenium methylidene. A second more-challenging substrate (dimethyl allylmethylallylmalonate) that forms a trisubstituted olefin product is used to further delineate the effect of catalyst structure on the relative efficiencies of these processes. A steric model is proposed to explain the observed trends

Rates of erosion and landscape change along the Blue Ridge escarpment, southern Appalachian Mountains, estimated from in situ cosmogenic 10Be

The Blue Ridge escarpment, located within the southern Appalachian Mountains of Virginia and North Carolina, forms a distinct, steep boundary between the lower-elevation Piedmont and higher-elevation Blue Ridge physiographic provinces. To understand better the rate at which this landform and the adjacent landscape are changing, we measured cosmogenic 10Be in quartz separated from sediment samples (n = 50) collected in thirty-two streams and from three exposed bedrock outcrops along four transects normal to the escarpment, allowing us to calculate erosion rates integrated over 104–105 years. These basin-averaged erosion rates (5.4–49 m My-1) are consistent with those measured elsewhere in the southern Appalachians and show a positive relationship between erosion rate and average basin slope. Erosion rates show no relationship with basin size or relative position of the Brevard fault zone, a fundamental structural element of the region. The cosmogenic isotopic data, when considered along with the distribution of average basin slopes in each physiographic province, suggest that the escarpment is eroding on average more rapidly than the Blue Ridge uplands, which are eroding more rapidly than the Piedmont lowlands. This difference in erosion rates by geomorphic setting suggests that the elevation difference between the uplands and lowlands adjacent to the escarpment is being reduced but at extremely slow rates