Peterseneriksen9606

The axion has emerged in recent years as a leading particle candidate to provide the mysterious dark matter in the cosmos, as we review here for a general scientific audience. We describe first the historical roots of the axion in the Standard Model of particle physics and the problem of charge-parity invariance of the strong nuclear force. We then discuss how the axion emerges as a dark matter candidate and how it is produced in the early universe. The symmetry properties of the axion dictate the form of its interactions with ordinary matter. Astrophysical considerations restrict the particle mass and interaction strengths to a limited range, which facilitates the planning of experiments to detect the axion. A companion review discusses the exciting prospect that the axion could be detected in the near term in the laboratory.Metabolic processes that fuel the growth of heterotrophic microbial communities are initiated by specialized biopolymer degraders that decompose complex forms of organic matter. It is unclear, however, to what extent degraders structure the downstream assembly of the community that follows polymer breakdown. Investigating a model marine microbial community that degrades chitin, we show that chitinases secreted by different degraders produce oligomers of specific chain lengths that not only select for specialized consumers but also influence the metabolites secreted by these consumers into a shared resource pool. Each species participating in the breakdown cascade exhibits unique hierarchical preferences for substrates, which underlies the sequential colonization of metabolically distinct groups as resource availability changes over time. By identifying the metabolic underpinnings of microbial community assembly, we reveal a hierarchical cross-feeding structure that allows biopolymer degraders to shape the dynamics of community assembly.Decidualization is an intricate biological process in which extensive remodeling of the endometrium occurs to support the development of an implanting blastocyst. However, the immunometabolic mechanisms underlying this process are still largely unknown. We found that the decidualization process is accompanied by the accumulation of fructose-1,6-bisphosphate (FBP). The combination of FBP with pyruvate kinase M stimulated IL-27 secretion by endometrial stromal cells in an ERK/c-FOS-dependent manner. IL-27 induced decidual COX-2+ M2-like macrophage differentiation, which promotes decidualization, trophoblast invasion, and maternal-fetal tolerance. Transfer of Ptgs2+/COX-2+ macrophages prevented fetal loss in Il27ra-deleted pregnant mice. FBP levels were low in plasma and decidual tissues of patients with unexplained recurrent spontaneous abortion. In therapeutic studies, FBP supplementation significantly improved embryo loss by up-regulation of IL-27-induced COX-2+ macrophage differentiation in a mouse model of spontaneous abortion. These findings collectively provide a scientific basis for a potential therapeutic strategy to prevent pregnancy loss.Nanoparticles, mRNA, and ultraviolet light combine to reprogram specific immune cells directly in the body.The preference for social novelty is crucial to the social life of humans and rodents. However, the neural mechanisms underlying social novelty preference are poorly understood. Here, we found that chronic social defeat stress (CSDS) reduced the preference for social novelty in mice by impairing the response of CaMKIIα+ neurons in the CA3 region of dorsal hippocampus (dCA3) during approach to an unfamiliar mouse. The deficits of social novelty preference in CSDS-treated mice were reversed by activating the output from dCA3 to the GABAergic neurons in the lateral septum (LS). The activation of GABAergic projection from LS recruited a circuit that inhibited the Foxb1+ neurons in the parvafox nucleus (PFN), which drove social avoidance by projecting to the lateral periaqueductal gray (lPAG). These results suggest that a previously unidentified circuit of dCA3CaMKIIα+→LSGABA+→PFNFoxb1+→lPAG mediates the deficits of social novelty preference induced by CSDS.Current state-of-the-art quantum dot light-emitting diodes have reached close to unity internal quantum efficiency. Further improvement in external quantum efficiency requires more efficient photon out-coupling. Improving the directivity of the photon emission is considered to be the most feasible approach. Here, we report improved emission directivity from colloidal quantum dot films. By growing an asymmetric compressive shell, we are able to lift their band-edge state degeneracy, which leads to an overwhelming population of exciton with in-plane dipole moment, as desired for high-efficiency photon out-coupling. The in-plane dipole proportion determined by back-focal plane imaging method is 88%, remarkably higher than 70% obtained from conventional hydrostatically strained colloidal quantum dots. Enhanced emission directivity obtained here opens a path to increasing the external quantum efficiencies notably.Antiferromagnet spintronic devices eliminate or mitigate long-range dipolar fields, thereby promising ultrafast operation. For spin transport electronics, one of the most successful strategies is the creation of metallic synthetic antiferromagnets, which, to date, have largely been formed from transition metals and their alloys. Here, we show that synthetic antiferrimagnetic sandwiches can be formed using exchange coupling spacer layers composed of atomically ordered RuAl layers and ultrathin, perpendicularly magnetized, tetragonal ferrimagnetic Heusler layers. Chemically ordered RuAl layers can both be grown on top of a Heusler layer and allow for the growth of ordered Heusler layers deposited on top of it that are as thin as one unit cell. The RuAl spacer layer gives rise to a thickness-dependent oscillatory interlayer coupling with an oscillation period of ~1.1 nm. The observation of ultrathin ordered synthetic antiferrimagnets substantially expands the family of synthetic antiferromagnets and magnetic compounds for spintronic technologies.The axion is a highly motivated elementary particle that could address two fundamental questions in physics-the strong charge-parity (CP) problem and the dark matter mystery. Experimental searches for this hypothetical particle started reaching theoretically interesting sensitivity levels, particularly in the micro-electron volt (gigahertz) region. They rely on microwave resonators in strong magnetic fields with signals read out by quantum noise limited amplifiers. Concurrently, there have been intensive experimental efforts to widen the search range by devising various techniques and to enhance sensitivities by implementing advanced technologies. These orthogonal approaches will enable us to explore most of the parameter space for axions and axion-like particles within the next decades, with the 1- to 25-gigahertz frequency range to be conquered well within the first decade. We review the experimental aspects of axion physics and discuss the past, present, and future of the direct search programs.Extensive studies in both animals and humans have demonstrated that high molecular weight neurochemicals, such as neuropeptides and other polypeptide neurochemicals, play critical roles in various neurological disorders. Despite many attempts, existing methods are constrained by detecting neuropeptide release in small animal models during behavior tasks, which leaves the molecular mechanisms underlying many neurological and psychological disorders unresolved. Here, we report a wireless, programmable push-pull microsystem for membrane-free neurochemical sampling with cellular spatial resolution in freely moving animals. In vitro studies demonstrate the sampling of various neurochemicals with high recovery (>80%). Open-field tests reveal that the device implantation does not affect the natural behavior of mice. The probe successfully captures the pharmacologically evoked release of neuropeptide Y in freely moving mice. This wireless push-pull microsystem creates opportunities for neuroscientists to understand where, when, and how the release of neuropeptides modulates diverse behavioral outputs of the brain.Hydrogen bond engineering is widely exploited to impart stretchability, toughness, and self-healing capability to hydrogels. However, the enhancement effect of conventional hydrogen bonds is severely limited by their weak interaction strength. In nature, some organisms tolerate extreme conditions due to the strong hydrogen bond interactions induced by trehalose. Here, we report a trehalose network-repairing strategy achieved by the covalent-like hydrogen bonding interactions to improve the hydrogels' mechanical properties while simultaneously enabling them to tolerate extreme environmental conditions and retain synthetic simplicity, which proves to be useful for various kinds of hydrogels. The mechanical properties of trehalose-modified hydrogels including strength, stretchability, and fracture toughness are substantially enhanced under a wide range of temperatures. After dehydration, the modified hydrogels maintain their hyperelasticity and functions, while the unmodified hydrogels collapse. This strategy provides a versatile methodology for synthesizing extremotolerant, highly stretchable, and tough hydrogels, which expand their potential applications to various conditions.While structural colors are ubiquitous in nature, saturated reds are mysteriously absent. This long-standing problem of achieving Schrödinger's red demands sharp transitions from "stopband" to a high-reflectance "passband" with total suppression of higher-order resonances at blue/green wavelengths. Current approaches based on nanoantennas are insufficient to satisfy all conditions simultaneously. Here, we designed Si nanoantennas to support two partially overlapping quasi-bound-states-in-the-continuum modes with a gradient descent algorithm to achieve sharp spectral edges at red wavelengths. Meanwhile, high-order modes at blue/green wavelengths are suppressed via engineering the substrate-induced diffraction channels and the absorption of amorphous Si. This design produces possibly the most saturated and brightest reds with ~80% reflectance, exceeding the red vertex in sRGB and even the cadmium red pigment. Its nature of being sensitive to polarization and illumination angle could be potentially used for information encryption, and this proposed paradigm could be generalized to other Schrödinger's color pixels.Oral protein delivery is considered a cutting-edge technology to improve patients' quality of life, offering superior patient compliance and convenience compared with injections. However, oral protein formulation has stagnated because of the instability and inefficient penetration of protein in the gastrointestinal tract. Here, we used acid-resistant metal-organic framework nanoparticles (UiO-68-NH2) to encapsulate sufficient insulin and decorated the exterior with targeting proteins (transferrin) to realize highly efficient oral insulin delivery. The UiO-68-NH2 nanocarrier with proper pore size achieved high insulin loading while protecting insulin from acid and enzymatic degradation. Through receptor-mediated transcellular pathway, the transferrin-coated nanoparticles realized efficient transport across the intestinal epithelium and controlled insulin release under physiological conditions, leading to a notable hypoglycemic effect and a high oral bioavailability of 29.6%. Our work demonstrates that functional metal-organic framework nanoparticles can protect proteins from the gastric environment and overcome the intestinal barrier, thus providing the possibility for oral biomacromolecule delivery.