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1. Meltwater Orientations Modify Seismic Anisotropy in Temperate Ice

   https://doi.org/10.1029/2024GL110131  

   Seltzer, Cassandra; Llorens, Maria‐Gema; Cross, Andrew_J (July 2024, Geophysical Research Letters)

   Abstract Seismology is increasingly used to infer the magnitude and direction of glacial ice flow. However, the effects of interstitial meltwater on seismic properties remain poorly constrained. Here, we extend previous studies on seismic anisotropy in temperate ices to consider the role of melt preferred orientation (MPO). We used the ELLE numerical toolbox to simulate microstructural shear deformation of temperate ice with variable MPO strength and orientation, and calculated the effective seismic properties of these numerical ice‐melt aggregates. Our models demonstrate that even 3.5% melt volume is sufficient to rotate fast directions by up to 90°, to increase Vp anisotropy by up to +110%, and to modify Vs anisotropy by −9 to +36%. These effects are especially prominent at strain rates ≥3.17 × 10⁻¹² s⁻¹. MPO may thus obscure the geophysical signatures of temperate ice flow in regions of rapid ice discharge, and is therefore pivotal for understanding ice mass loss. 

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2. Evolution of the Josephine Peridotite Shear Zones: 1. Compositional Variation and Shear Initiation

   https://doi.org/10.1029/2019GC008399  

   Kumamoto, Kathryn M.; Warren, Jessica M.; Hauri, Erik H. (December 2019, Geochemistry, Geophysics, Geosystems)

   Abstract Shear localization in the upper mantle, a necessity for plate tectonics, can have a number of causes, including shear heating, the presence of melt, the development of a strong crystal preferred orientation, and the presence of water. The Josephine Peridotite of southwestern Oregon contains shear zones that provide an excellent opportunity to examine the initiation of shear localization. These shear zones are relatively small scale and low strain compared to many shear zones in peridotite massifs, which typically have extreme grain size reduction indicating extensive deformation. We use major, trace, and volatile element analyses of a large suite of harzburgites from the Fresno Bench shear zones to evaluate the mechanisms leading to shear localization. Lithological evidence and geochemical transects across three shear zones show a complex history of melting, melt addition, and melt‐rock interaction. The distribution of aluminum and heavy rare earth elements across the shear zones suggest that melt flow was focused in the centers of the studied shear zones. Water concentrations in orthopyroxene grains of 180–334 ppm H₂O indicate a comparatively high degree of hydration for nominally anhydrous minerals. The correlation of water with aluminum and ytterbium in orthopyroxene is consistent with a melt source for this hydration, suggesting that water equilibrated between the melt and peridotite. The presence of melt and hydration of the host rock provide mechanisms for initial weakening that lead to localized deformation. 

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3. Effects of an External Magnetic Field on Keyhole Mode Laser Melting of 316 Stainless Steel

   https://doi.org/10.1007/s11837-025-07400-4  

   Bafahm_Alamdari, Aslan; Clark, Samuel; Fezzaa, Kamel; Wolff, Sarah (May 2025, JOM)

   Abstract Keyhole-mode laser melting is an efficient method for joining or cutting large, thick components, but controlling keyhole depth and fluctuations has remained challenging. Applying an external magnetic field can control melt pool flows and indirectly influence keyhole morphology and dynamics. The induced Lorentz force, comprising Seebeck and damping components, plays a crucial role in the melt pool dynamics, depending on temperature gradient, flow rates, and magnetic field orientation and magnitude. This research investigates the effects of an external magnetic field on keyhole behavior during laser spot melting of 316 stainless steel using synchronized high-speed synchrotron X-ray and thermal imaging. Findings revealed that a longitudinal magnetic field (120 mT) increased keyhole depth but exacerbated lateral fluctuations, resulted in a 20% increase in the melt pool temperature gradient and a 27% decrease in cooling rate. Conversely, a transverse magnetic field (760 mT) reduced keyhole depth and improved porosity formation. The findings suggest that a decrease in keyhole depth correlates with a decrease in fluctuations, and vice versa. These insights enhance understanding of external magnetic fields’ impact on laser melting, with implications for improving part quality. 

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4. Trans-crustal structural control of CO2-rich extensional magmatic systems revealed at Mount Erebus Antarctica

   https://doi.org/10.1038/s41467-022-30627-7  

   Hill, G. J.; Wannamaker, P. E.; Maris, V.; Stodt, J. A.; Kordy, M.; Unsworth, M. J.; Bedrosian, P. A.; Wallin, E. L.; Uhlmann, D. F.; Ogawa, Y.; et al (December 2022, Nature Communications)

   Abstract Erebus volcano, Antarctica, with its persistent phonolite lava lake, is a classic example of an evolved, CO 2 -rich rift volcano. Seismic studies provide limited images of the magmatic system. Here we show using magnetotelluric data that a steep, melt-related conduit of low electrical resistivity originating in the upper mantle undergoes pronounced lateral re-orientation in the deep crust before reaching shallower magmatic storage and the summit lava lake. The lateral turn represents a structural fault-valve controlling episodic flow of magma and CO 2 vapour, which replenish and heat the high level phonolite differentiation zone. This magmatic valve lies within an inferred, east-west structural trend forming part of an accommodation zone across the southern termination of the Terror Rift, providing a dilatant magma pathway. Unlike H 2 O-rich subduction arc volcanoes, CO 2 -dominated Erebus geophysically shows continuous magmatic structure to shallow crustal depths of < 1 km, as the melt does not experience decompression-related volatile supersaturation and viscous stalling. 

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5. Twisted Crystalline Organic Semiconductor Photodetectors

   https://doi.org/10.1002/adfm.202212531  

   Jeong, Sehee; Barbosa, Natercia; Tiwari, Akash; Holland, Emma_K; Huang, Ling‐Yi; Bhat, Vinayak; Yang, Yongfan; Zhang, Yuze; Whittaker, St_John; Kim, Min‐Woo; et al (March 2023, Advanced Functional Materials)

   Abstract Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out‐of‐plane orientations of 5,11‐bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band‐dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation‐dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3‐ and 6.2‐times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals. 

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