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In this study, two types of soils with varying soil water potentials were used for evaluating the effect of gravity on water flow through unsaturated soils. Experiments were conducted in both 1- and 0-g environments. Water content distributions were evaluated as a function of distance from the source of water intake and time. The experimental results indicated that the capillary potential and the advective forces due to interfacial tension gradients are overshadowed by the gravitational potential in a 1-g environment. The fast water movement in the 0-g condition is attributed to the capillary potential as well as to the advective forces that developed. In addition, microstructural changes have contributed to water flow in the 0-g condition. Depending on soil type, the magnitude of such an effect (i.e., water movement) varies from three- to four-fold. To analyze the experimental results, a one-dimensional model, based on Darcy’s law and the conservation of mass equations, was developed and solved numerical...

We used microelectrodes to monitor the recovery (i.e., decrease) of intracellular pH (pHi) after using internal dialysis to load squid giant axons with alkali to pHi values of 7.7, 8.0, or 8.3. The dialysis fluid (DF) contained 400 mM K+ but was free of Na+ and Cl-. The artificial seawater (ASW) lacked Na+, K+, and Cl-, thereby eliminating effects of known acid-base transporters on pHi. Under these conditions, halting dialysis unmasked a slow pHi decrease caused at least in part by acid-base transport we refer to as "base efflux." Replacing K+ in the DF with either NMDG+ or TEA+ significantly reduced base efflux and made membrane voltage (Vm) more positive. Base efflux in K(+)-dialyzed axons was stimulated by decreasing the pH of the ASW (pHo) from 8 to 7, implicating transport of acid or base. Although postdialysis acidifications also occurred in axons in which we replaced the K+ in the DF with Li+, Na+, Rb+, or Cs+, only with Rb+ was base efflux stimulated by low pHo. Thus, the base effluxes supported by K+ and Rb+ appear to be unrelated mechanistically to those observed with Li+, Na+, or Cs+. The combination of 437 mM K+ and 12 mM HCO3- in the ASW, which eliminates the gradient favoring a hypothetical K+/HCO3- efflux, blocked pHi recovery in K(+)-dialyzed axons. However, the pHi recovery was not blocked by the combination of 437 mM Na+, veratridine, and CO2/HCO3- in the ASW, a treatment that inverts electrochemical gradients for H+ and HCO3- and would favor passive H+ and HCO3- fluxes that would have alkalinized the axon. Similarly, the recovery was not blocked by K+ alone or HCO3- alone in the ASW, nor was it inhibited by the K-H pump blocker Sch28080 nor by the Na-H exchange inhibitors amiloride and hexamethyleneamiloride. Our data suggest that a major component of base efflux in alkali-loaded axons cannot be explained by metabolism, a H+ or HCO3- conductance, or by a K-H exchanger. However, this component could be mediated by a novel K/HCO3- cotransporter.

The pyrolysis and crystallization of poly(methacrylate) precursors and xerogels of forsterite and chromium- doped forsterite were studied by in situ high-temperature, dynamic X-ray diffraction and thermal analysis. For both types of precursor, crystallization of forsterite occurred at lower temperature when doped with chromium. Also, exotherms above 700° C occurred 50°C lower when chromium was present. When residual carbon in the xerogels was more than ∼ 1%, an unidentified crystalline intermediate phase formed at ∼ 800° C. Conversion of the intermediate phase to forsterite was easier than amorphous material. Thus, full crystallinity was attained at a lower temperature when the xerogels had some residual carbon

A novel polymer precursor method for the preparation of silicates including enstatite-free forsterite is being investigated. Precursors to crystalline materials were prepared via the copolymerization of the K and/or Mg salts of methacrylic acid with various combinations of a siloxane-methacrylate and a methoxysilyl-methacrylate Thermogravimetric/differential thermal, pyrolysis mass spectrometry, and high-temperature X-ray diffraction analyses were used to monitor the conversion of the precursors to inorganic oxide during air pyrolysis. Some precursors to crystalline oxides showed yields as high as 77% of theoretical.

Contains fulltext : 34787.pdf (Publisher’s version ) (Closed access) We present the results of follow-up observations of white-dwarf + M-dwarf binaries identified using spectra obtained as part of the SPY survey. Spectra of the Halpha region were obtained with the SPIRAL spectrograph on the AAT telescope. Of the eleven stars observed, seven are binaries with periods in the range 2.8 hours to 7.7 days. We also show that one of our targets, WD 0137-349, has a brown dwarf companion. 15th European Workshop on White Dwarfs