Phys.org September 6, 2024 Nanocellulose from biomass is promising for manufacturing sustainable composite biomaterials and bioplastics. However, obtaining nanocellulose at pilot scale requires energy-intensive fibrillation to shear cellulose fibers apart into nano-dimensional forms in water. To reduce the energy consumption in fibrillation a team of researchers in the US (Oak Ridge National Laboratory, University of Maine) found that aqueous NaOH:urea (0.007:0.012 wt.%) reduced the fibrillation energy by ~21% on average relative to water alone. The NaOH and urea acted synergistically on CNFs to aid fibrillation but at different length scales. According to the researchers their work suggested a general mechanism […]
Tag Archives: S&T USA
Materials scientists develop road map for designing responsive gels with unusual properties
Phys.org August 22, 2024 Metallo-polyelectrolytes are versatile materials for applications like filtration, biomedical devices, and sensors, due to their metal-organic synergy. Their dynamic and reversible electrostatic interactions offer high ionic conductivity, self-healing, and tunable mechanical properties. However, the knowledge gap between molecular-level dynamic bonds and continuum-level material properties persist, largely due to limited fabrication methods and a lack of theoretical design frameworks. To address this gap researchers at Caltech developed a framework, combining theoretical and experimental insights, highlighting the interplay of molecular parameters in governing material properties. Using stereolithography-based additive manufacturing, they produced durable metallo-polyelectrolytes gels with tunable mechanical properties […]
Sound drives ‘quantum jumps’ between electron orbits
Phys.org August 26, 2024 Coherent quantum control is an essential tool for understanding and mitigating decoherence. Characterizing and controlling orbital states is a central challenge for quantum networking, where optical coherence is tied to orbital coherence. Researchers at Cornell University studied resonant multi phonon orbital Rabi oscillations extracting the strength of the orbital-phonon interactions and the coherence of the acoustically driven orbital states. They reached the strong-driving limit, where the physics was dominated by coupling induced by the acoustic waves. They found agreement between their measurements, quantum master-equation simulations, and a Landau-Zener transition model in the strong-driving limit. They modeled […]
Pyramid optical networks for unidirectional image magnification and demagnification
Phys.org August 1, 2024 Researchers at UC California developed a pyramid-structured diffractive optical network design (P-D2NN), optimized specifically for unidirectional image magnification and demagnification. The diffractive layers were pyramidally scaled in alignment with the direction of the image magnification or demagnification, to inhibit image formation in the opposite direction, thus achieved the desired unidirectional imaging operation using a much smaller number of diffractive degrees of freedom within the optical processor volume. The design maintained its unidirectional image magnification/demagnification functionality across a large band of illumination wavelengths. It allowed a unidirectional magnifier and a unidirectional demagnifier operation simultaneously in opposite directions, […]
Researchers identify useful emission lines in the sun’s outer atmosphere
Phys.org August 2, 2024 When studying the solar spectrum, researchers often search for emission spectra of two iron ions, Fe IX and Fe X, which are useful for studying the sun’s outer atmosphere. However, both spectra contain emission lines that cannot be matched with known electron transitions, limiting the information which can be gathered from them. A team of researchers in the US (Columbia University, Lawrence Livermore National Laboratory, UC Berkeley) presented measurements made in the wavelength range 238–258 Å which helped them to identify the charge state associated with each of the observed lines. This wavelength range was of […]
Method prevents an AI model from being overconfident about wrong answers
MIT News July 31, 2024 Recent studies have found that common interventions such as instruction tuning often result in poorly calibrated large language models (LLMs). Although calibration is well-explored in traditional applications, calibrating LLMs is uniquely challenging. The challenges stem as much from the severe computational requirements of LLMs as from their versatility, which allows them to be applied to diverse tasks. To address these challenges, researchers at MIT proposed THERMOMETER, a calibration approach tailored to LLMs. For calibrating the LLMTHERMOMETER learned an auxiliary model, using the data given from multiple tasks. According to the researchers it was computationally efficient, […]
New research underscores the close relationship between Saharan dust and hurricane rainfall
Phys.org July 24, 2024 The impact of global climate changes on Tropical Cyclone Rainfall (TCR) is complex and debatable. A team of researchers in the US (Western Michigan State University, Stanford University, Perdue University, University of Utah, Caltech) used an XGBoost machine learning model with 19-year meteorological data and hourly satellite precipitation observations to predict TCR for individual storms. The model identified dust optical depth (DOD) as a key predictor that enhances performance evidently. The model uncovered a nonlinear and boomerang-shape relationship between Saharan dust and TCR, with a TCR peak at 0.06 DOD and a sharp decrease thereafter. This […]
Raindrops grow with turbulence in clouds: New findings could improve weather and climate models
Phys.org July 25, 2024 A team of researchers in the US (NSF National Center for Atmospheric Research, industry) provided substantial evidence for significant impacts of turbulence on the evolution of cloud droplet size distributions and rain formation by comparing high-resolution observations of cumulus congestus clouds with state-of-the-art large-eddy simulations coupled with a Lagrangian particle-based microphysics scheme. Turbulence causes earlier rain formation and greater rain accumulation compared to simulations with gravitational coalescence only. The observed rain size distribution tail just above cloud base follows a power law scaling that deviates from theoretical scalings considering either a purely gravitation collision kernel or […]
Researchers trap atoms, force them to serve as photonic transistors
Phys.org July 29, 2024 It remains a challenging task to efficiently trap a large ensemble of cold atoms on an integrated nanophotonic circuit. Researchers at Purdue University demonstrated direct loading of an ensemble of up to 70 atoms into an optical microtrap on a nanophotonic microring circuit by employing degenerate Raman-sideband cooling in the microtrap, where a built-in spin-motion coupling arose directly from the vector light shift of the evanescent-field potential on a microring. Atoms were cooled into the trap via optical pumping with a single free space beam. They achieved a trap lifetime approaching 700 ms under continuous cooling. […]
Scared to negotiate job offers? Study suggests you should do it anyway
Phys.org July 18, 2024 A team of researchers in the US (George Mason University, Stony Brook University, University of Pennsylvania) proposed that one major issue that individuals are concerned about in the context of job offers, is an offer being withdrawn from the bargaining table—losing out on a deal entirely. They investigated job candidates’ perceived likelihood of jeopardizing a deal, as compared to hiring managers’ reports, across seven studies, including surveys of academic job candidates and members of academic hiring committees, managers and hiring professionals, and experimental studies with interactive, incentivized negotiations conducted both in person and online. They found […]