RESUMEN
We report on small optical reflection increases after illumination of nanometer thick gold and aluminum thin films on different substrates with single, femtosecond 400 nm wavelength pump laser pulses, in a pre-ablation fluence regime. In this fluence regime, small, irreversible and subtle morphological changes of the sample are observed. Dark-field, scanning electron, and atomic force microscopy images reveal subwavelength spallation features in the aluminum, and delamination in the gold layers in this pre-ablation regime. All of these morphological changes coincide with minute optical increases in the reflectivity, at the 0.1-2% level, as observed in-situ with a weak probe beam. From Liu-analysis, transfer-matrix, and two-temperature model calculations, we infer that in this pre-ablation regime, the aluminum layers already reach the melting temperature. Electron Backscatter Diffraction measurements show that the Al grains melt and resolidify into bigger grains. This suggests that for Al, resolidification into bigger grains is responsible for both the increased reflection, and the spallation in the pre-ablation regime. For gold, the optical change is most likely due to the etalon effect caused by delamination.
RESUMEN
We describe a new treefrog species from Lao Cai Province, northwestern Vietnam. The new species is assigned to the genus Zhangixalus based on a combination of the following morphological characters: (1) dorsum green, smooth; body size medium (SVL 30.1-32.2 in males); (2) fingers webbed; tips of digits expanded into large disks, bearing circum-marginal grooves; (3) absence of dermal folds along limbs; (4) absence of supracloacal fold and tarsal projection. The new species can be distinguished from its congeners by: (1) dorsal surface of the head and body green without spots; (2) axilla and groin cream with a black blotch; (3) ventral cream without spot; (4) chin creamy with grey marbling; anterior part of the thigh and ventral surface of tibia orange without spots; posterior parts of thigh orange with a large black blotch; (5) ventral side of webbing orange with some grey pattern (6) iris red-bronze, pupils black; (7) finger webbing formula I1»-1»II1-2III1-1IV, toe webbing formula I½-½II0-1½III»-1¾IV1¾-½V. Phylogenetically, the new species is nested in the same subclade as Z.jodiae, Z.pinglongensis, and Z.yaoshanensis, with genetic distances ranging from 3.23% to 4.68%. The new species can be found in evergreen montane tropical forests at an elevation of about 1,883 m a.s.l. This new discovery brings the number of known genus Zhangixalus species to 42 and the number of species reported from Vietnam to 10.
RESUMEN
The desire to commercialize perovskite solar cells continues to mount, motivating the development of scalable production. Evaluations of the impact of open-air processing have revealed a variety of physical changes in the fabricated devicesâwith few changes having the capacity to be functionalized. Here, we highlight the beneficial role of ambient oxygen during the open-air thermal processing of metastable γ-CsPbI3-based perovskite thin films and devices. Physiochemical-sensitive probes elucidate oxygen intercalation and the formation of Pb-O bonds in the CsPbI3 crystal, entering via iodine vacancies at the surface, creating superoxide (O2-) through electron transfer reactions with molecular oxygen, which drives the formation of a zero-dimensional Cs4PbI6 capping layer during annealing (>330 °C). The chemical conversion permanently alters the film structure, helping to shield the subsurface perovskite from moisture and introduces lattice anchoring sites, stabilizing otherwise unstable γ-CsPbI3 films. This functional modification is demonstrated in γ-CsPbI2Br perovskite solar cells, boosting the operational stability and photoconversion efficiency of champion devices from 12.7 to 15.4% when annealed in dry air. Such findings prompt a reconsideration of glovebox-based perovskite solar cell research and establish a scenario where device fabrication can in fact greatly benefit from ambient oxygen.
RESUMEN
A new species of the genus Vietnamophryne is described from Vietnam on the basis of two specimens collected from Tuyen Quang Province, Northeastern Vietnam. The new species is morphologically most similar to Vietnamophryne occidentalis from Thailand, however, it differs from the latter by having large black blotches in the lower jaw region, and a yellow-orange chest and belly. The genetic distance between the new species and other Vietnamophryne taxa is > 2.13% (16S mtDNA gene fragment). Vietnamophryne aurantifusca sp. nov. can be distinguished from all other species of Vietnamophryne by a combination of the following morphological characteristics: Size medium (SVL 17.618.2 mm in males); head wider than long; tympanum medium; finger I longer than half of finger II; dorsal skin relatively smooth with some round nodules, concentrated in the middle of the back, arranged along the length of the back, with a prominent ridge along the spine; Dorsum orangish-brown entirely and paler on margin of back with a small brownish ridge along the spine; sides brownish with creamy patches and orange spots; ventral surface orange, with grey marbling, most intense on the throat, ventral side of arms and thighs, and ventral surfaces of limbs dark grey with some orange spots.