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1. MicroLED light source for optical sectioning structured illumination microscopy

   https://doi.org/10.1364/OE.486754  

   Kumar, Vikrant; Behrman, Keith; Speed, Forest; Saladrigas, Catherine A.; Supekar, Omkar; Huang, Zicong; Bright, Victor M.; Welle, Cristin G.; Restrepo, Diego; Gopinath, Juliet T.; et al (May 2023, Optics Express)

   Optical sectioning structured illumination microscopy (OS-SIM) provides optical sectioning capability in wide-field microscopy. The required illumination patterns have traditionally been generated using spatial light modulators (SLM), laser interference patterns, or digital micromirror devices (DMDs) which are too complex to implement in miniscope systems. MicroLEDs have emerged as an alternative light source for patterned illumination due to their extreme brightness capability and small emitter sizes. This paper presents a directly addressable striped microLED microdisplay with 100 rows on a flexible cable (70 cm long) for use as an OS-SIM light source in a benchtop setup. The overall design of the microdisplay is described in detail with luminance-current-voltage characterization. OS-SIM implementation with a benchtop setup shows the optical sectioning capability of the system by imaging within a 500 µm thick fixed brain slice from a transgenic mouse where oligodendrocytes are labeled with a green fluorescent protein (GFP). Results show improved contrast in reconstructed optically sectioned images of 86.92% (OS-SIM) compared with 44.31% (pseudo-widefield). MicroLED based OS-SIM therefore offers a new capability for deep tissue widefield imaging. 

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2. High-speed in vivo calcium recording using structured illumination with self-supervised denoising

   https://doi.org/10.1364/OPTCON.532996  

   Speed, Forest; Saladrigas, Catherine A; Teel, Alec; Vieau, Sean; Bright, Victor M; Gopinath, Juliet T; Welle, Cristin G; Restrepo, Diego; Gibson, Emily A (January 2024, Optics Continuum)

   High-speed widefield fluorescence imaging of neural activity in vivo is fundamentally limited by fluctuations in recorded signal due to background contamination and stochastic noise. In this study, we show background and shot noise-reduced imaging of the ultrafast genetically encoded Ca²⁺indicator GCaMP8f in CA1 pyramidal neurons using periodic structured illumination (SI) with computational image reconstruction. We implement what we believe to be a novel reconstruction method for data acquired using periodic structured illumination, termed pseudo-HiLo (pHiLo), that combines a pseudo-widefield (pWF) reconstruction with individual SI frames to perform a HiLo reconstruction. We compare this new technique to interleaved optical sectioning structured illumination microscopy (OS-SIM) and pWF reconstruction. We quantify the performance of each reconstruction by evaluating contrast, transient peak-to-noise ratio (PNR), pairwise correlation coefficients between ΔF/F time courses extracted from individual in-focus cells, and correlation coefficients between each cell with surrounding cell-free background pixels. We additionally incorporate a self-supervised deep learning method for real-time noise suppression (DeepCAD-RT) into our data preprocessing pipeline. At 500 Hz frame rates, we demonstrate a 75% increase in PNR using the denoised pHiLo reconstruction compared to pWF. Utilizing DeepCAD-RT, we show significant PNR improvements using both structured illumination (SI) reconstruction methods with OS-SIM showing a 59% increase in PNR after denoising. Both pHiLo and OS-SIM reconstructions result in a ≈65% decrease in the mean correlation coefficient of the ΔF/F time courses between ROIs in comparison with pWF, indicating the potential to remove background fluorescent transients from out-of-focus cells. 

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3. The Marine Organic Sulfur Cycle

   https://doi.org/10.1146/annurev-marine-040124-105229  

   Raven, Morgan Reed (August 2025, Annual Review of Marine Science)

   Organic sulfur (OS) in the ocean is produced in vast quantities by primary producers that fix inorganic sulfate into proteins, metabolites, and other ubiquitous biomolecules. As biogenic OS is transported and transformed through the marine environment, it is joined by OS from two additional sources: abiogenic OS from sulfurization under anoxic conditions, and geological OS from the weathering of sediments and rocks. Important differences in the properties of the OS from these sources affect its fate in the environment and underlie the formation of recalcitrant dissolved organic matter and sedimentary kerogen. This review builds connections between the rapid OS cycle in the surface ocean and these longer-lived reservoirs, applying our growing knowledge of particle fluxes and organic matter dynamics at the sediment–water interface. Future studies on marine OS are poised to help us better understand the implications of these fluxes for the carbon cycle and climate across human and geological timescales. 

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4. Isoelectronic perturbations to f - d -electron hybridization and the enhancement of hidden order in URu ₂ Si ₂

   https://doi.org/10.1073/pnas.2026591118  

   Wolowiec, Christian T.; Kanchanavatee, Noravee; Huang, Kevin; Ran, Sheng; Breindel, Alexander J.; Pouse, Naveen; Sasmal, Kalyan; Baumbach, Ryan E.; Chappell, Greta; Riseborough, Peter S.; et al (May 2021, Proceedings of the National Academy of Sciences)

   null (Ed.)

   Electrical resistivity measurements were performed on single crystals of URu 2– x Os x Si 2 up to x = 0.28 under hydrostatic pressure up to P = 2 GPa. As the Os concentration, x , is increased, 1) the lattice expands, creating an effective negative chemical pressure P ch ( x ); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure P c is required to induce the HO→LMAFM phase transition. We compare the behavior of the T ( x , P ) phase boundary reported here for the URu 2- x Os x Si 2 system with previous reports of enhanced HO in URu 2 Si 2 upon tuning with P or similarly in URu 2– x Fe x Si 2 upon tuning with positive P ch ( x ). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URu 2 Si 2 . We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5 f -electron and transition metal d -electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URu 2 Si 2 . Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5 f -electron states and the d -electron states of Ru and its isoelectronic Fe and Os substituents in URu 2 Si 2 . 

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5. Reversing File Access Control Using Disk Forensics on Low-Level Flash Memory

   https://doi.org/10.3390/jcp4040038  

   Rother, Caleb; Chen, Bo (October 2024, Journal of Cybersecurity and Privacy)

   In the history of access control, nearly every system designed has relied on the operating system (OS) to enforce the access control protocols. However, if the OS (and specifically root access) is compromised, there are few if any solutions that can get users back into their system efficiently. In this work, we have proposed a novel approach that allows secure and efficient rollback of file access control after an adversary compromises the OS and corrupts the access control metadata. Our key observation is that the underlying flash memory typically performs out-of-place updates. Taking advantage of this unique feature, we can extract the “stale data” specific for OS access control, by performing low-level disk forensics over the raw flash memory. This allows efficiently rolling back the OS access control to a state pre-dating the compromise. To justify the feasibility of the proposed approach, we have implemented it in a computing device using file system EXT2/EXT3 and open-sourced flash memory firmware OpenNFM. We also evaluated the potential impact of our design on the original system. Experimental results indicate that the performance of the affected drive is not significantly impacted. 

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