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We report the successful synthesis of monodispersed Cu2S nanocrystals and the subsequent formation of highly ordered nanocrystal superlattices. The synthesis is performed under ambient air conditions using simple experimental setups, making the process both accessible and scalable. By systematically tuning the reaction temperature and duration, we demonstrate precise control over the nanocrystal size, which is crucial in achieving uniformity and monodispersity. Furthermore, we uncover a previously unidentified nanocrystal growth mechanism that plays a key role in producing highly monodisperse Cu2S nanocrystals. This insight into the growth process enhances our fundamental understanding of nanocrystal formation and could be extended to the synthesis of other semiconductor nanomaterials. The self-assembly of these nanocrystals into superlattices is carefully examined using electron diffraction techniques, revealing the presence of pseudo-crystalline structures. The ordered arrangement of nanocrystals within these superlattices suggests strong interparticle interactions and opens up new possibilities to tailor their collective optical, electronic, and mechanical properties for potential applications in optoelectronics, nanomedicine, and energy storage. 

ABSTRACT Nonmuscle myosin II (NMII) generates cytoskeletal forces that drive cell division, embryogenesis, muscle contraction and many other cellular functions. However, at present there is no method that can directly measure the forces generated by myosins in living cells. Here, we describe a Förster resonance energy transfer (FRET)-based tension sensor that can detect myosin-associated force along the filamentous actin network. Fluorescence lifetime imaging microscopy (FLIM)-FRET measurements indicate that the forces generated by NMII isoform B (NMIIB) exhibit significant spatial and temporal heterogeneity as a function of donor lifetime and fluorophore energy exchange. These measurements provide a proxy for inferred forces that vary widely along the actin cytoskeleton. This initial report highlights the potential utility of myosin-based tension sensors in elucidating the roles of cytoskeletal contractility in a wide variety of contexts. 

Abstract. Measurements of atmospheric O2have been used to quantify large-scalefluxes of carbon between the oceans, atmosphere and landsince 1992 (Keeling and Shertz, 1992). With time,datasets have grownand estimates of fluxes have become more precise, buta key uncertainty in these calculations is the exchange ratioof O2and CO2 associated with the net land carbon sink(αB). We present measurements of atmosphericO2 and CO2 collected overa 6-year period from a mixed deciduous forest in centralMassachusetts, USA (42.537∘ N, 72.171∘ W).Using a differential fuel-cell-basedinstrument for O2 and a nondispersive infrared analyzer forCO2, we analyzed airstreams collected within and ∼5 m above the forest canopy. Averaged over the entireperiod of record, we find these two species covary with a slope of -1.081±0.007 mol of O2 per mole ofCO2 (themean and standard error of 6 h periods).If we limit the data to values collected on summer days within thecanopy, the slope is -1.03±0.01. These are the conditions in whichbiotic influences are most likely to dominate.This result is significantlydifferent from the value of −1.1 widely used in O2-basedcalculations of the global carbon budget, suggesting the need for a deeper understanding of the exchange ratios of the various fluxes and pools comprising the net sink.