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The distribution and character of Venus's impact craters led to the widely accepted idea that Venus underwent global catastrophic resurfacing ca. 500 Ma, and thus Venus records only a short history, encompassing surface evolution since postulated catastrophic resurfacing. Ribbon tessera terrain (RTT), a structurally distinctive unit, represents some of Venus's oldest surfaces, and is widely accepted as forming prior to postulated global catastrophic resurfacing. We constructed a global geologic map of RTT unit exposures and structural trends using National Aeronautics and Space Administration (NASA) Magellan data. Map relations illustrate that RTT displays planet-scale patterns that, together with altimetry, record a rich geologic history that predates proposed global catastrophic resurfacing.

Elongated micro-and nanostructures of Sn doped or Sn and Cr codoped monoclinic gallium oxide have been grown by a thermal method. The presence of Sn during growth has been shown to strongly influence the morphology of the resulting structures, including Sn doped branched wires, whips, and needles. Subsequent codoping with Cr is achieved through thermal diffusion for photonic purposes. The formation mechanism of the branched structures has been studied by transmission electron microscopy (TEM). Epitaxial growth has been demonstrated in some cases, revealed by a very high quality interface between the central rod and the branches of the structures, while in other cases, formation of extended defects such as twins has been observed in the interface region. The influence of dopants on the energy levels of Ga and O within the structures has been studied by XPS. Micro-Raman spectroscopy was used to assess the influence of Sn doping, and Sn−Cr codoping, on the vibrational properties of single nanowires. Cathodoluminescence (CL) measurements show a Sn-related complex band in the Sn-doped structures. Temperature-dependent and excitation-density-dependent CL indicates that this is a thermally activated emission. In the Sn− Cr codoped samples, the characteristic, very intense Cr 3+ red luminescence emission quenches the bands observed in the Sndoped samples. Branched, Sn−Cr codoped structures were studied with microphotoluminescence imaging and spectroscopy, and waveguiding behavior was observed along the trunks and branches of these structures.

Recent construction of 1:10 M IMaps of Niobe Planitia and Aphrodite Terra paints a rich picture of Venus evolution. Using the Niobe‐Aphrodite map area (>25% of Venus) as an example, we illustrate the methodology and importance of detailed structural mapping at large regional scales in order to identify tectonic domains that lead to the discovery of global‐scale geodynamic evolution and operative processes. We highlight differences between lithodemic and lithostratigraphic units in geologic mapping. We step through a series of structural element maps that reveal the character of at least three different tectonic domains and evolving tectonic regimes that reflect changing geodynamic processes, here divided into three eras. The ancient era encompasses formation of tessera terrain and represents a time of unique global and environmental conditions marked by globally thin lithosphere. The second era resulted in formation of the Artemis superstructure. The ~13,000‐km‐diameter footprint of the Artemis superstructure is huge but not global, although associated mantle flow patterns could have had a global reach. As formation of the Artemis superstructure waned, tectonic activity became more focused leading to formation of the fracture zone complex. This complex extends beyond the map area connecting with Atla, Beta, and Themis regiones and associated fracture zones, marking the youngest era. Structural mapping of the Niobe‐Aphrodite map area indicates that Venus exhibits a complex, multistage history like other terrestrial planets, which probably extends to several billion years. Given that Venus never developed plate tectonics, Venus' preserved surface record is likely significantly richer than that of Earth.

The Meseta de Somuncura forms the largest basaltic plateau (20 000 km2) of southern Argentina (extra‐Andean domain). Most of these tholeiitic to alkaline rocks were extruded at ˜ 25 Ma (late Oligocene). The absence of rifting–thinning processes, plume activity, or slab‐window phenomena leaves only one major possibility for the generation of Somuncura: asthenospheric (‘OIB‐like’) corner flow leading to a transient thermal anomaly above the subducting plate. It is suggested herein that the intake of hot asthenosphere was forced into a favourable topography (concave‐up) of the subducting plate, when a major plate reorganization event (Farallon to Nazca) was taking place in late Oligocene to early Miocene time. The fast and vigorous intake of asthenosphere would have been induced by slab roll‐back, leading to decoupling of the subducting plate. The Somuncura volcanic episode can be regarded as a marker of the passage from the extremely oblique subduction of Farallon, to the birth of the Nazca plate and roughly perpendicular convergence between South America and Nazca.

The influence of indium doping on morphology, structural, and luminescence properties of gallium oxide microand nanostructures is reported. Indium-doped gallium oxide micro-and nanostructures have been grown by thermal oxidation of metallic gallium in the presence of indium oxide. The dominant morphologies are beltlike structures, which in many cases are twisted leading to springlike structures, showing that In diffusion in Ga 2 O 3 influences the microstructure shapes. High-resolution transmission electron microscopy has revealed the presence of twins in the belts, and energy-dispersive X-ray spectroscopy in the scanning electron microscopy (SEM) has detected a segregation of indium impurities at the edges of planar structures. These results suggest that indium plays a major role in the observed morphologies and support the assumption of a layer by layer model as growth mechanism. An additional assessment of indium influence on the defect structure has been performed by cathodoluminescence in the SEM, X-ray photoelectron microscopy, and spatially resolved Raman spectroscopy.

The coexistence curves of the system dodecylammonium chloride+water+KCl have been measured at different salt concentrations. The results can be described with the usual Ising 3-D value for the critical exponent β=0.325. The analysis of the diameter indicates that the correct order parameter is defined in terms of an effective concentration calculated according to Eq. (4). Both the order parameter and the diameter of the coexistence curve point out that the range of validity of simple scaling decreases with the KCl concentration, i.e., as the system approaches a critical end point. The critical line, and an estimation of the Krafft temperatures have allowed us to estimate the position of the critical end point within the T-w-[KCl] space, w indicating the weight fraction of the surfactant. The pressure dependence of the critical temperature has been measured and found to be independent of the salt content for the present range of concentrations.