Assessment of the Water Quality in the Salt River Prior to Its Impoundment in Anderson and Spencer Counties, Kentucky

Monthly water samples were taken and analyzed to determine the water quality of the Salt River in Anderson and Spencer counties Kentucky prior to the river\u27s impoundment. Sediments from the area watershed were analyzed to total acid digestion, barium chloride extraction, and aqueous extraction methods. Rainwater and runoff water were collected and analyzed for major cations and anions from two sites in the watershed. The Salt River at Taylorsville is characterized by hard water with high levels of calcium (33.5-74.8 mg/1), bicarbonate (136-236 mg/l), specific conductance (200-535 μmhos/cm), and sulfate (16.5-71.5 mg/l). Nitrates (0.6-5.7 mg/l), phosphates (0.2-2.4 mg/l), sodium (3.2-20.3 mg/l), and potassium (1.3-5.6 mg/l), are moderate. Iron, manganese, copper, and nitrites are less than 0.5 mg/1. Suspended solids in the river (4.0-l ,684.0 mg/l) are highly variable and directly related to fluctuations in discharge. Sediments from the Salt River Basin are high in potassium (12.4-213.3 mg/g) and iron (23.4-135.1 mg/g), with moderate levels of calcium (0.8-45.7 mg/g), sodium (4.5-10.5 mg/g), magnesium (3.2-6.3 mg/g), and phosphate (1.3-15.3 mg/g). Approximately 10% of the total ionic composition of these sediments is exchangeable and may be extracted with barium chloride. Calcium (309-3,292 μg/g), was the most readily adsorbed cation, with lower levels of potassium (17.6-490.5 μg/g), sodium (12.9-458.1 μg/g), and magnesium (89.4-266.2 μg/g). In the aqueous extractions, calcium (18-486 μg/g), potassium (16.6-69.5 μg/g), sodium (11.1-30.8 μg/g), and magnesium (6.6-68.7 μg/g) comprised about 10% of the exchangeable fraction. Ranges of rainwater ions from the Salt River Basin were: sulfate (8.3-27.8 mg/l), calcium (0.3-10.7 mg/l), potassium (0.4-15.4 mg/l), sodium (0.0-0.7 mg/l), and magnesium (0.1-2.8 mg/l). Ionic composition and sediment yield of runoff water was variable and was related to magnitude of rainfall and runoff sampler placement. Ranges for selected constituents at the two samplers near Taylorsville were: suspended solids (44.0-8,808.0 mg/l), potassium (1.1-84.0 mg/l), magnesium (l.5-7.1 mg/l), calcium (9.5-33.0 mg/l), and sodium (0.6-3.0 mg/l). Calcium and bicarbonate in the Salt River originate from weathering of calcite, although mole ratios of these two ions greater than 1:2 suggest that weathering of magnesium carbonates also contributes bicarbonate to the water. Carbonate equilibrium calculations using field pH and ionic strength suggest calcium is at saturation in the Salt River. High levels of sulfate in rainwater indicate some of this anion may be introduced into the area watershed by atmospheric precipitation

Progranulin Gene Variability and Plasma Levels in Bipolar Disorder and Schizophrenia

Basing on the assumption that frontotemporal lobar degeneration (FTLD), schizophrenia and bipolar disorder (BPD) might share common aetiological mechanisms, we analyzed genetic variation in the FTLD risk gene progranulin (GRN) in a German population of patients with schizophrenia (n = 271) or BPD (n = 237) as compared with 574 age-, gender- and ethnicity-matched controls. Furthermore, we measured plasma progranulin levels in 26 German BPD patients as well as in 61 Italian BPD patients and 29 matched controls

Design of a Trichromatic Cone Array

Cones with peak sensitivity to light at long (L), medium (M) and short (S) wavelengths are unequal in number on the human retina: S cones are rare (<10%) while increasing in fraction from center to periphery, and the L/M cone proportions are highly variable between individuals. What optical properties of the eye, and statistical properties of natural scenes, might drive this organization? We found that the spatial-chromatic structure of natural scenes was largely symmetric between the L, M and S sensitivity bands. Given this symmetry, short wavelength attenuation by ocular media gave L/M cones a modest signal-to-noise advantage, which was amplified, especially in the denser central retina, by long-wavelength accommodation of the lens. Meanwhile, total information represented by the cone mosaic remained relatively insensitive to L/M proportions. Thus, the observed cone array design along with a long-wavelength accommodated lens provides a selective advantage: it is maximally informative

Induction-model analysis of Si-H stretching mode in Porous Silicon

A detailed study of Si-H stretching in porous silicon was performed based on the induction model. Good agreement with experimental infrared absorption spectra was achieved considering the oxygen nearest-neighbors and next nearest-neighbors. Carbon presence in the samples was detected and its influence on Si-H stretching was determined

Ca-silicides as prototypical systems for modelling the electron-states at the Si(111)/Yb interface: a Si- L2,3 Auger lineshape investigation

The valence electron states at the Si(111)(2• 1)/Yb interface are discussed in terms of the Si L2,3VV Auger lineshape. The existence of Si 3p/Yb 5d interaction is inferred on the basis ofstrong similarities observed between the Si L2,3VV lineshapes of the interface reaction products and those of Ca silicides. Detailed spectroscopic assignments in the distribution of the valencestates are made possible by comparing the experimental spectra to theoretical calculations performed within the LMTO-ASA scheme

NEXAFS measurement of the p-symmetry unoccupied states of silver, palladium and palladium silicide

The density of unoccupied p states of silver, palladium, and palladium silicide has been measured for the first time with high resolution by x-ray absorption at the MIV,V edges. Our results show that the MIV,V-edge spectra yield information for 4d metals similar to that provided by K and LI edge measurement on 3d metals. The densities of states are in agreement with theoretical predictions both in regard to energy and relative intensity. Changes in the palladium MIV,V spectra on silicide formation give the first direct evidence of the role of Pd 5p states in compound formation

Optical properties of isolated and interacting silicon quantum wires

We have studied the effect of hydrogen passivation and inter-wire interaction on the electronic structure and optical properties of nanoscale Si wires through two first-principle techniques: linear muffin tin orbitals method in the atomic sphere approximation (LMTO-ASA) and norm-conserving pseudopotential. We have considered free, partially and totally H-passivated [001] Si quantum wires with various rectangular cross-sections; moreover we have investigated the inter-wire interaction, by varying the wire density. The optical properties have been computed by evaluating the imaginary part of the dielectric function and the absorption coefficient. We find that wires with diameters as small as 10-25 Angstrom are active in the visible range. Inter-wire interaction leads to the presence of localized interface states which lower the bandgap energy. These results are important for the discussion about the dimensionality of confined Si quantum particles in porous Si and for the debate on quantum confinement models

Silicon valence states in calcium silicides: A Si- L2,3 VV lineshape analysis

We present a Si L2,3VV Auger line-shape analysis of the whole set of Ca silicides, Ca2Si, CaSi, and CaSi2. Measured spectra are compared, after data processing, to theoretical ones, computed within the framework of a one-electron picture. The overall good agreement found in this comparison allows us to understand the observed Si L2,3VV spectral changes in terms of the Si valence states’ evolution across the whole family of Ca silicides. The narrowing of the pp spectral region and the appearance of a distinct sp shoulder observed on going from CaSi2 to Ca2Si are related, respectively, to the decreased width of the Si 3p band and to the narrowing of the Si 3s states together with their increased energy separation from the Si 3p states. A breakdown of the one-electron picture is observed in Ca2Si. We find that this effect is due to the quasiatomic configuration of the Si 3s states in this compound. The introduction of a correlation energy between two sp-like–final-state holes improves the comparison between theory and experiment, but does not appear to fully account for the Si L2,3VV spectrum from Ca2Si. New theoretical effort is therefore needed to understand this spectrum

Chemical bond and electronic states in calcium silicides: theory and comparison with synchrotron radiation photoemission

We present a combined theoretical and experimental investigation of the electron properties of calcium silicides (Ca2Si, CaSi, and CaSi2). The theoretical study is performed by a self-consistent calculation of the electron states, while the experimental analysis is based on synchrotron-radiation photoemission measurements. The overall agreement between the computed and measured spectra allows us to investigate the main features of the Ca-Si interaction in different compounds. We find that covalent character is present in the Ca-Si bond and that the strength of this interaction increases with Si concentration. Furthermore all the Ca s-p-d states are involved in this coupling with Si. In Ca2Si, the Si s states are found in a corelike configuration, while in the other compounds they are promoted to form an s-p valence band. The covalent interaction is not sufficient to interpret the results and some ionic character is present in the Ca-Si bond. Ca2Si is found to be a semimetal and many structures in the density of states can be correlated to well-defined interactions between the nonequivalent Ca-Si couples that are found in these complex compounds