Ring laser gyroscopes (RLGs) measure rotation via the Sagnac effect: a slight difference in the frequency of the two counter-propagating beams within the resonator. However, at low rotation rates, an intrinsic limitation...Ring laser gyroscopes (RLGs) measure rotation via the Sagnac effect: a slight difference in the frequency of the two counter-propagating beams within the resonator. However, at low rotation rates, an intrinsic limitation in RLGs, known as the lock-in phenomenon, counteracts this effect, precluding the widespread adoption of RLGs as motion sensors. Past efforts to avoid this phenomenon include mechanical dithering and magneto-optic non-reciprocity techniques. Such techniques require external components that limit the miniaturization of RLGs. Here we present a self-biased method that overcomes this limitation through chiral spontaneous symmetry breaking and nonlinear frequency pulling in a He-Ne RLG without inserted elements. Supported by a theoretical model that reveals phase transition conditions with spontaneous symmetry breaking and the dynamics of bistable chiral states, our experiments demonstrate deterministic chirality switching synchronized with rotation direction. Remarkably, the chiral RLG has a linear frequency response at near-zero rotation rates, achieving an open-loop bias instability of 2.2 × 10 degrees per hour at a 10 s integration time. Our work presents a strategy for the development of all-solid-state, high-precision and miniaturized laser gyroscopes, which could be used for the exploration of the interplay of nonlinear dynamics and spontaneous symmetry breaking in photonic systems.
Nucleoside-modified mRNA-lipid-nanoparticle (mRNA-LNP) vaccines confer a high level of protection against severe COVID-19 and, since their first authorization for human use in 2020, have saved millions of lives. The effi...Nucleoside-modified mRNA-lipid-nanoparticle (mRNA-LNP) vaccines confer a high level of protection against severe COVID-19 and, since their first authorization for human use in 2020, have saved millions of lives. The efficacy of this vaccine platform relies on the induction of powerful and coordinated innate and adaptive immune responses. A deep understanding of the mechanisms of action by which mRNA-LNP vaccines drive protective immunity is crucial for advancing the development of next-generation mRNA vaccines with improved immunogenicity and tolerability. A flurry of recent studies has shed light on aspects of this vaccine modality's modus operandi. Nonetheless, key gaps in knowledge remain, including understanding how LNPs are sensed by the immune system and exert their adjuvant activity, identifying the specific signals and cellular pathways critical for eliciting protective immune responses and determining whether it is feasible to uncouple vaccine immunogenicity and reactogenicity. Here we review the known and unknown features of the immunological mechanisms of mRNA-LNP vaccines for infectious diseases. Furthermore, we discuss how the components of this vaccine platform can be modified to fine-tune immune responses against challenging pathogens for which effective vaccines do not exist or need improvement.
Atmospheric and vacuum distillation consume more than 1,100 TWh year and emit more than 160 million metric tonnes of CO equivalent annually, making membrane-based pre-fractionation a compelling retrofit strategy for lowe...Atmospheric and vacuum distillation consume more than 1,100 TWh year and emit more than 160 million metric tonnes of CO equivalent annually, making membrane-based pre-fractionation a compelling retrofit strategy for lowering the energy and carbon intensity of petroleum refining. Here we demonstrate that porous polyacrylonitrile (PAN) membranes, typically used as support layers, achieve effective molecular refining of crude oil at steady state. Under tangential flow, PAN membranes exhibited high crude oil permeances of up to 0.591 ± 0.040 l m h bar, a more than 23-fold increase over the previous benchmark (<0.1 l m h bar), selectively yielding enriched lighter hydrocarbon fractions such as naphtha and kerosene. This unexpected selectivity arises from the dynamic deposition of heavy hydrocarbons within the initially approximately 15-nm surface mesopores, which narrows the pore diameter to sub-2-nm dimensions. Depth-resolved chemical identification reveals selective accumulation of n-alkanes, suggesting a self-limiting pore constriction mechanism that stabilizes selective transport pathways. Once the n-alkane deposition is stabilized, selective enrichment of raw crude oils occurs with sustained stability over 4 weeks. Process simulations show that PAN-membrane-based pre-fractionation could reduce energy by 31.6%, cooling water by 20.7% and CO emissions by 37.6% compared with traditional atmospheric distillation.
Van Der Straeten D, Bulut M, Cao D
… +12 more, Aharoni A, Bouis H, Granell A, Gruissem W, Lindberg Møller B, Martin C, Puchta H, Sreenivasulu N, Tissier A, Tripathi L, Van Montagu M, Fernie AR
At present, more than 700 million people live with caloric hunger, and more than two billion suffer from micronutrient deficiencies, known as 'hidden hunger'. From an agricultural viewpoint, three major objectives need t...At present, more than 700 million people live with caloric hunger, and more than two billion suffer from micronutrient deficiencies, known as 'hidden hunger'. From an agricultural viewpoint, three major objectives need to be worked towards simultaneously to achieve zero hunger (the United Nations Sustainable Development Goal 2): (1) enhanced yield; (2) higher vitamin and mineral density to sustain recommended daily intake (multi-biofortification); and (3) enhanced climate-change resilience. Although the Green Revolution increased global calorie production, it exacerbated hidden hunger by prioritizing high yield over nutritional quality. Stress from global climate change has been shown to reduce the densities of several micronutrients. CRISPR-Cas, which allows genome editing with extremely high precision, has emerged as a groundbreaking breeding technology that has already been adopted by many countries. Here we examine how CRISPR-Cas-based approaches could be used to achieve biofortification targets by enhancing micronutrient densities to the levels necessary to alleviate dietary vitamin and mineral deficiencies. Given the limited time frame available to achieve zero hunger, we argue that CRISPR-Cas technologies should be combined with metabolic engineering based on transformation and other technologies. We also consider untapped resources beyond metabolic pathways and current CRISPR-Cas methodologies to address one of the most important societal issues of the twenty-first century.
CHIME/FRB Collaboration, Andersen BC, Bandura K
… +59 more, Bhardwaj M, Boyle PJ, Brar C, Breitman D, Cassanelli T, Chatterjee S, Chawla P, Cliche JF, Cubranic D, Curtin AP, Deng M, Dobbs M, Dong FA, Fonseca E, Gaensler BM, Giri U, Good DC, Hill AS, Josephy A, Kaczmarek JF, Kader Z, Kania J, Kaspi VM, Leung C, Li DZ, Lin HH, Masui KW, Mckinven R, Mena-Parra J, Merryfield M, Meyers BW, Michilli D, Naidu A, Newburgh L, Ng C, Ordog A, Patel C, Pearlman AB, Pen UL, Petroff E, Pleunis Z, Rafiei-Ravandi M, Rahman M, Ransom S, Renard A, Sanghavi P, Scholz P, Shaw JR, Shin K, Siegel SR, Singh S, Smith K, Stairs I, Tan CM, Tendulkar SP, Vanderlinde K, Wiebe DV, Wulf D, Zwaniga A