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1. LMT/AzTEC observations of Vega

   https://doi.org/10.1093/mnras/stac1510  

   Marshall, J P; Chavez-Dagostino, M; Sanchez-Arguelles, D; Matrà, L; del Burgo, C; Kemper, F; Bertone, E; Dent, W_R F; Vega, O; Wilson, G; et al (June 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT Vega is the prototypical debris disc system. Its architecture has been extensively studied at optical to millimetre wavelengths, revealing a near face-on, broad, and smooth disc with multiple distinct components. Recent millimetre-wavelength observations from ALMA spatially resolved the inner edge of the outer, cold planetesimal belt from the star for the first time. Here we present early science imaging observations of the Vega system with the AzTEC instrument on the 32-m LMT, tracing extended emission from the disc out to 150 au from the star. We compare the observations to three models of the planetesimal belt architecture to better determine the profile of the outer belt. A comparison of these potential architectures for the disc does not significantly differentiate between them with the modelling results being similar in many respects to the previous ALMA analysis, but differing in the slope of the outer region of the disc. The measured flux densities are consistent between the LMT (single dish) and ALMA (interferometric) observations after accounting for the differences in wavelength of observation. The LMT observations suggest the outer slope of the planetesimal belt is steeper than was suggested in the ALMA analysis. This would be consistent with the interferometric observations being mostly blind to structure at the disc outer edges, but the overall low signal to noise of the LMT observations does not definitively resolve the structure of the outer planetesimal belt. 

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2. Developing a Large-Scale Cryogenic System for the Simultaneous Operation of Three Detector Focal Planes in TolTEC, A New Multichroic Imaging Polarimeter

   https://doi.org/10.1007/s10909-019-02319-y  

   DeNigris, N. S.; Wilson, G. W.; Eiben, M. E.; Lunde, E.; Mauskopf, P.; Contente, R. (May 2020, Journal of Low Temperature Physics)

   TolTEC is an upcoming millimeter-wave imaging polarimeter designed to fill the focal plane of the 50-m-diameter Large Millimeter Telescope (LMT). Combined with the LMT, TolTEC will offer high-angular-resolution (5–10 ) simultaneous, polarization-sensitive observations in three wavelength bands: 1.1, 1.4, and 2.0 mm. Additionally, TolTEC will feature mapping speeds greater than 2 deg2∕mJy2∕h , thus enabling wider surveys of large-scale structure, galaxy evolution, and star formation. These improvements are only possible through the integration of approximately 7000 low-noise, high-responsivity superconducting Lumped Element Kinetic Inductance Detectors. Utilizing three focal planes of detector arrays requires the design, fabrication, and characterization of a unique, large-scale cryogenic system. Based on thermal models and expected photon loading, the focal planes must have a base operational temperature below 150 mK. To achieve this base temperature, TolTEC utilizes two cryocoolers, a Cryomech pulse tube cooler and an Oxford Instruments dilution refrigerator, to establish four thermal stages: 45 K, 4 K, 1 K, and 100 mK. During the design phase, we developed an object-oriented Python code to model the heat loading on each stage as well as the thermal gradients throughout the system. This model has allowed us to improve thermal gradients in the system as well as locate areas of poor thermal conductivity prior to ending a cooldown. The results of our model versus measurements from our cooldowns will be presented along with a detailed overview of TolTEC’s cryogenic system. We anticipate TolTEC to be commissioned at the LMT by Spring 2020. 

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3. Effect of chemical defects on electrostriction-enhanced piezoelectric property of poly(vinylidene fluoride) via high-power ultrasonication

   https://doi.org/10.1016/j.nanoen.2023.108590  

   Rui, Guanchun; Allahyarov, Elshad; Zhang, Honghu; Li, Ruipeng; Zhang, Shihai; Taylor, Philip L.; Zhu, Lei (August 2023, Nano Energy)

   Among all ferroelectric polymers, poly(vinylidene fluoride) (PVDF)-based polymers exhibit the best piezoelectric properties and thus are promising for sensors, actuators, and energy harvesters in flexible/wearable electronics and soft robotics. Despite decades of research effort, the structure-property relationship is still unclear for ferroelectric polymers, and their piezoelectric performance is often limited to ~30 pC/N. In this study, we report the effects of chemical defects [i.e., the head-to-head and tail-to-tail (HHTT) sequence] and high-power ultrasonication on the piezoelectric performance of PVDF. Two PVDF homopolymers with different HHTT contents were studied. The PVDF with a lower HHTT content (4.3%) exhibited a higher melting temperature (Tm, denoted as HMT), whereas that with a higher HHTT content (5.9%) exhibited a lower Tm (denoted as LMT). In addition to the primary crystals (PCs) and the isotropic amorphous fraction, wide-angle X-ray diffraction also suggested the presence of the oriented amorphous fraction (OAF) and secondary crystals (SCs), which are important in enhancing the piezoelectricity for PVDF. Intriguingly, the LMT PVDF exhibited higher piezoelectric performance than the HMT PVDF, because it had a higher OAF/SC content. In addition, high-power ultrasonication was shown to effectively break relaxor-like SCs off from the PCs, further enhancing the piezoelectric performance. That is, the inverse piezoelectric coefficient d31 reached as high as 76.2 pm/V at 65 °C for the ultrasonicated LMT PVDF. The insight from this study will enable us to design better piezoelectric PVDF polymers for practical electromechanical applications. 

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4. LMTOY: The LMT Single Dish Spectral Line Toolkit

   Teuben, Peter; Heyer, Mark; Mundy, Lee; Narayanan, Gopal; Pound, Marc; Rauch, Kevin; Sanchez, David; Schloerb, F Peter; Souccar, Kamal; Yun, Min (May 2024, ASP Conference Series)

   With the goal of adding Science Ready Data Products to the archive of the Large Millimeter Telescope (LMT), we have developed a toolkit that allows automated pipeline processing of LMT single dish spectral line data. The data products include automatic source detection and spectral line detection using the ALMA Data Mining Toolkit (ADMIT). Adopting SDFITS as the interchange format, we aim that other observatories can use our toolkit and that LMT data can be analyzed by other packages. Interoperability tests are planned for this. In addition to the on-site Quick Look products, we now produce Timely Analysis Products (TAP) within 15 minutes after the observation has ended for an on-the-fly map, and much faster for pointed observations. These provide the scientist with rapid feedback on the scientific content. 

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5. A prototype submersible sheathless flow cytometer designed for autonomous platforms

   https://doi.org/10.1002/lom3.70007  

   Swalwell, J E; Cain, K; Armbrust, E V (October 2025, Limnology and Oceanography: Methods)

   Abstract Development of submersible flow cytometers has allowed for continuous, in situ measurements of natural assemblages of phytoplankton cells. Here we introduce DeepCyte, a sensitive prototype submersible flow cytometer developed for deployment on autonomous platforms. DeepCyte continuously collects multidimensional characteristics of individual phytoplankton cells (~0.5–10 μm in diameter), includingProchlorococcus, and transmits this data in real‐time to remote observatories via a network connection. DeepCyte utilizes a virtual sample core technology and an open flow system, enabling direct measures from the surrounding environment without the use of a clean carrier fluid. The primary surfaces of excitation and collection optics are exposed to the outside of the instrument, and the only fluid path is a 6 mm diameter length of silicon tubing. These design features allow for simple maintenance of optical surfaces and minimize sampling downtime due to clogs or air bubbles. An innovative arrangement of the optical system means the instrument fits within a volume of 0.017 m³, and our selection and design of low power electronics yield power consumption of 36 watts when operated as a standalone instrument with integrated pump. The DeepCyte is characterized by high optical sensitivity, low power consumption, compact size, and low maintenance. This technology will provide a continuous view of the dynamics and structure of the smallest phytoplankton populations, aligning with and expanding upon other continuous measurements such as chlorophyll‐afluorescence, temperature, and salinity. 

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