Description: We have determined matrix elements for all experimental configurations of Ca  iii , including the 3s3p 6 3d configuration. These values have been obtained using intermediate coupling (IC). For these IC calculations, we have used the standard method of least-squares fitting from the experimental energy levels, using the computer code developed by Robert Cowan. In this paper, using these matrix elements, we report the calculated values of the Ca  iii Stark widths and shifts for 148 spectral lines, of 56 Ca  iii spectral line transition probabilities and of eight radiative lifetimes of Ca  iii levels. The Stark widths and shifts, calculated using the Griem semi-empirical approach, correspond to the spectral lines of Ca  iii and are presented for an electron density of 10 17 cm –3 and temperatures T  = 1.0–10.0 ( x 10 4 K). The theoretical trends of the Stark broadening parameter versus the temperature are presented for transitions that are of astrophysical interest. There is good agreement between our calculations, for transition probabilities and radiative lifetimes, and the experimental values presented in the literature. We have not been able to find any values for the Stark parameters in the references.

Description: In the present work we report theoretical Stark widths and shifts calculated using the Griem semi-empirical approach, corresponding to 237 spectral lines of Mg iii . Data are presented for an electron density of 10 17 cm –3 and temperatures T  = 0.5–10.0 (10 4 K). The matrix elements used in these calculations have been determined from 23 configurations of Mg iii : 2s 2 2p 6 , 2s 2 2p 5 3p, 2s 2 2p 5 4p, 2s 2 2p 5 4f and 2s 2 2p 5 5f for even parity and 2s 2 2p 5 n s ( n  = 3–6), 2s 2 2p 5 n d ( n  = 3–9), 2s 2 2p 5 5g and 2s2p 6 n p ( n  = 3–8) for odd parity. For the intermediate coupling (IC) calculations, we use the standard method of least-squares fitting from experimental energy levels by means of the Cowan computer code. Also, in order to test the matrix elements used in our calculations, we present calculated values of 70 transition probabilities of Mg iii spectral lines and 14 calculated values of radiative lifetimes of Mg iii levels. There is good agreement between our calculations and experimental radiative lifetimes. Spectral lines of Mg iii are relevant in astrophysics and also play an important role in the spectral analysis of laboratory plasma. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. No values of Stark parameters can be found in the bibliography.

Description: Geologic disposal of spent nuclear fuel in high-capacity metal canisters may reduce the repository footprint, but it may yield high-thermal loads (up to 300 °C). The focus of this experimental work is to expand our understanding of the hydrothermal stability of bentonite clay barriers interacting with metallic phases under different geochemical, mineralogical, and engineering conditions. The hydrothermal experiments were performed using flexible Au/Ti Dickson reaction cells mounted in an externally heated pressure vessel at 150–160 bars and temperatures up to 300 °C for five to six weeks. Unprocessed Wyoming bentonite, containing primarily montmorillonite with minor amount of clinoptilolite, was saturated with a K-Ca-Na-Cl-bearing water (~1900 mg/L total dissolved solids) at a 9:1 water:rock mass ratio. The bentonite and solution combination contained either steel plates or Cu-foils and were buffered to low Eh using magnetite and metallic iron. During reactions, pH, K + , and Ca 2+ concentrations decreased, whereas SiO 2(aq) , Na + , and SO 4 2– concentrations increased throughout the experiments. Pyrite decomposition was first observed at ~210 °C, generating H 2 S (aq,g) that interacted with metal plates or evolves as a gas. The aqueous concentrations of alkali and alkaline earth cations appear to be buffered via montmorillonite and clinoptilolite exchange reactions. Illite or illite/smectite mixed-layer formation was significantly retarded in the closed system due to a limited K + supply along with high Na + and SiO 2(aq) concentrations. Precursor clinoptilolite underwent extensive recrystallization during the six weeks, 300 °C experiments producing a Si-rich analcime in addition to authigenic silica phases (i.e., opal, cristobalite). Analcime and feldspar formation partially sequester aqueous Al 3+ , thereby potentially inhibiting illitization. Associated with the zeolite alteration is a ~17% volume decrease (quartz formation) that translates into ~2% volume loss in the bulk bentonite. These results provide chemical information that can be utilized in extending the bentonite barriers’ lifetime and thermal stability. Zeolite alteration mineralogy and illitization retardation under these experimental conditions is important for the evaluation of clay barrier long-term stability in a spent nuclear fuel repository.

Description: Ca iv emission lines are under the preview of Solar Ultraviolet Measurements of Emitted Radiation device aboard the Solar and Heliospheric Observatory . Also, lines of the Ca iv in planetary nebulae NGC 7027 were detected with the Short Wavelength Spectrometer on board the Infrared Space Observatory . These facts justify an attempt to provide new spectroscopic parameters of Ca iv . There are no theoretical or experimental Stark broadening data for Ca iv . Using the Griem semi-empirical approach and the cowan code, we report in this paper calculated values of the Stark broadening parameters for 467 lines of Ca iv . They were calculated using a set of wavefunctions obtained by using Hartree–Fock relativistic calculations. These lines arising from 3s 2 3p 4 n s ( n  = 4, 5), 3s 2 3p 4 4p, 3s 2 3p 4 n d ( n  = 3, 4) configurations. Stark widths and shifts are presented for an electron density of 10 17 cm –3 and temperatures T  = 10 000, 20 000 and 50 200 K. As these data cannot be compared to others in the literature, we present an analysis of the different regularities of the values presented in this work.

Description: The western Kuqa fold-thrust belt of Xinjiang Province, China, hosts a series of surface salt structures. Here we present preliminary analysis of the geometry, kinematics, and surface processes of three of these structures: the Quele open-toed salt thrust sheet, Tuzimazha salt wall, and Awate salt fountain. The first two are line-sourced, the third appears to be point-sourced, and all are active. The ~35-km-long, 200-m-thick Quele open-toed salt thrust sheet features internal folding, salt-lined transfer structures, dissolution topography, flanking growth strata, and alluvial fan/stream-network interactions. The ~10-km-long, 50-m-wide Tuzimazha salt wall marks a local topographic high, such that fluvial stream networks are deflected by the rising weak tabular salt body. The salt wall is also flanked by growth strata and normal faults. The ~2-km-long Awate salt fountain represents salt exhumation coincident with the intersection of multiple structures and a river. Therefore this salt body may respond to local structural and/or erosional variations, or it may play a key role determining such variations—or both. Activity along all three structures confirms that active deformation occurs from foreland to hinterland across the western Kuqa fold-thrust belt. Gradual lateral transition from bedded strata to flow-banded halite observed within the Quele open-toed salt thrust sheet implies that similar transitions observed in seismic reflection data do not require interpretation as diapiric cut-off relationships. The surface salt structures of the western Kuqa fold-thrust belt display a variety of erosion-tectonics interactions, with nuances reflecting the low viscosity and high erodibility of salt, including stream deflections, potential tectonic aneurysm development, and even an upper-crustal test site for channel flow–focused denudation models.