Structural Modification from Centrosymmetric Rb4Hg2Ge2S8 to Noncentrosymmetric (Na3Rb)Hg2Ge2S8: Mixed Alkali-metals Strategy for Infrared Nonlinear Optical Material Design

Noncentrosymmetric (NCS) structure is the precondition for second-order nonlinear optical (NLO) materials. In this work, we present a new strategy for constructing NCS structures, that mixed alkali-metals made a new...

The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

Non-Arrhenian Temperature-Dependent Viscosity of Alkali(ne) Carbonate Melts at Mantle Pressures

The viscosity of carbonate melts is a fundamental parameter to constrain their migration and ascent rates through the mantle and ultimately, their role as carbon conveyors within the deep carbon cycle. Yet, data on the viscosity of carbonate melts have remained scarce due to experimental limitations and the lack of appropriate theoretical descriptions for molten carbonates. Here, we report the viscosity of K2Mg(CO3)2 and K2Ca(CO3)2 melts up to 13 GPa and 2,000 K by means of classical molecular dynamics (MD) simulations using optimized force fields and provide first evidence for non-Arrhenian temperature-dependent viscosity of molten carbonates at mantle pressures. The viscosity of K2Mg(CO3)2 and K2Ca(CO3)2 melts ranges respectively between 0.0056–0.0875 Pa s and 0.0046–0.0650 Pa s in the investigated pressure-temperature interval. Alkali(ne) carbonate melts, i.e. mixed alkali and alkaline earth carbonate melts -K2Mg(CO3)2 and K2Ca(CO3)2− display higher viscosity than alkaline earth carbonate melts -CaCO3 and MgCO3− at similar conditions, possibly reflecting the change in charge distribution upon addition of potassium. The non-Arrhenian temperature-dependence of the viscosity is accurately described by the Vogel-Fulcher-Tammann model with activation energies Ea for viscous flow that decrease with temperature at all investigated pressures, e.g. from ∼100 kJ/mol to ∼30 kJ/mol between 1,300 and 2,000 K at 3 GPa. Pressure is found to have a much more moderate effect on the viscosity of alkali(ne) carbonate melts, with activation volumes Va that decrease from 4.5 to 1.9 cm3/mol between 1,300 and 2,000 K. The non-Arrhenian temperature-viscosity relationship reported here could be exhibited by other carbonate melt compositions as observed for a broad range of silicate melt compositions and it should be thus considered when modeling the mobility of carbonate melts in the upper mantle.

317 Effect of the Whole Cottonseed with Pre-treatment on the Digestibility, Productivity, and Milk Fat Profile of Dairy Cattle

To improve the efficiency of whole cottonseed (WCS) on dairy cattle, crush and alkali treatment were combined (Table 1) in this study. The gastrointestinal tract digestibility of WCS were measured by in situ ruminal incubation and in vitro fermentation, respectively. Finally, animal feeding experiment was conducted to evaluate the effect of processed WCS on dairy cattle. A total of 30 Holstein dairy cows with similar physiological status were allocated to three groups (CON, Group I, and Group II). Ration for the CON group was a basic ration with no WCS, ration with about 8% non-processed WCS was for Group I (DM basis), while the Group II was provided by the ration added with 8% Crush-Alkali (4% mixed alkali solids with NaOH/CaO ratio at 1:1) treated WCS. Results of the in situ and in vitro experiments showed that, compared with non-treated WCS, Crushing-Alkali treatment groups significantly improved WCS ruminal effective degradation rate of dry matter (DM), crude protein (CP), ether extract (EE), and neutral detergent fiber (NDF) (P &lt; 0.05). Furthermore, Crush-Alkali (4% mixed alkali solids with NaOH/CaO ratio at 1:1) was the most beneficial to improve WCS gastrointestinal degradation of DM, CP and NDF, as well as enhance WCS rumen-bypass of EE. With the lowest free gossypol content (P&lt; 0.05). Results of animal feeding experiment showed that DMI, 4% fat corrected milk production (4% FCM), milk protein, milk fat, and content of short-chain saturated fatty acids in milk in Group II significantly increased (P &lt; 0.05) compared with CON group. DMI, ω-6 polyunsaturated fatty acids (PUFA) in milk, and the ratio of ω-6 to ω-3 PUFA were significantly higher in Group II than that in Group I (P &lt; 0.05). Additionally, free gossypol concentration in serum and milk, as well as parameters reflecting liver function were not notably different among the three groups (P &gt; 0.05).