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Overwhelming scientific evidence shows that CO 2 emissions from fossil fuels have caused the climate to change, and a dramatic reduction of these emissions is essential to reduce the risk of future devastating effects. On the other hand, access to energy is the basis of much of the current and future prosperity of the world. Eighty percent of this energy is derived from fossil fuel. The world has abundant fossil fuel reserves, particularly coal. The United States possesses one-quarter of the known coal supply, and the United States, Russia, China, and India account for two-thirds of the reserves. Coal accounts for roughly 25% of the world energy supply and 40% of the carbon emissions. * It is highly unlikely that any of these countries will turn their back on coal any time soon, and for this reason, the capture and storage of CO 2 emissions from fossil fuel power plants must be aggressively pursued.

Whereas standard transmission electron microscopy studies are unable to preserve the native state of chemically reactive and beam-sensitive battery materials after operation, such materials remain pristine at cryogenic conditions. It is then possible to atomically resolve individual lithium metal atoms and their interface with the solid electrolyte interphase (SEI). We observe that dendrites in carbonate-based electrolytes grow along the (preferred), , or directions as faceted, single-crystalline nanowires. These growth directions can change at kinks with no observable crystallographic defect. Furthermore, we reveal distinct SEI nanostructures formed in different electrolytes.

For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g –1 ) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm –2 . The Coulombic efficiency improves to ∼99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes. Hollow carbon nanospheres form a stable solid electrolyte interphase on lithium metal anodes that suppresses dendrite growth and improves cycling Coulombic efficiency.

Clocking on to relativity A central prediction of general relativity states that a gravitational field slows the running of a clock. Previous measurements of this effect, known as gravitational redshift, have involved clocks at different heights, and until now this has been the least accurately determined of the parameters supporting curved space-time theories. Now this prediction has been confirmed to unprecedented accuracy using the results of lab experiments performed more than 10 years ago in a study of the acceleration of free fall. Analysis of the data — on quantum interference of single caesium atoms bobbing up and down in an atomic fountain — provides a measurement based on matter-wave interference that improves accuracy by a factor of 10,000. One of the central predictions of general relativity is that a clock in a gravitational potential well runs more slowly than a similar clock outside the well. This effect, known as gravitational redshift, has been measured using clocks on a tower, an aircraft and a rocket, but here, laboratory experiments based on quantum interference of atoms are shown to produce a much more precise measurement. One of the central predictions of metric theories of gravity, such as general relativity, is that a clock in a gravitational potential U will run more slowly by a factor of 1 +  U / c 2 , where c is the velocity of light, as compared to a similar clock outside the potential 1 . This effect, known as gravitational redshift, is important to the operation of the global positioning system 2 , timekeeping 3 , 4 and future experiments with ultra-precise, space-based clocks 5 (such as searches for variations in fundamental constants). The gravitational redshift has been measured using clocks on a tower 6 , an aircraft 7 and a rocket 8 , currently reaching an accuracy of 7 × 10 -5 . Here we show that laboratory experiments based on quantum interference of atoms 9 , 10 enable a much more precise measurement, yielding an accuracy of 7 × 10 -9 . Our result supports the view that gravity is a manifestation of space-time curvature, an underlying principle of general relativity that has come under scrutiny in connection with the search for a theory of quantum gravity 11 . Improving the redshift measurement is particularly important because this test has been the least accurate among the experiments that are required to support curved space-time theories 1 .

Objectives Mindfulness-based interventions have been widely applied to various populations with demonstrated effects in reducing physical and psychological distress. However, it is equally important to investigate whether, and how, mindfulness might enhance people’s psychological well-being. One important dimension of well-being is meaning in life. We systematically analyzed the correlational relationship between mindfulness and meaning in life and whether randomized controlled trials of mindfulness-based interventions could enhance meaning in life. Methods A comprehensive literature search identified 22 studies (25 samples, N = 7895) for the meta-analysis of the relationship between mindfulness and meaning in life, and 9 studies (11 samples, N = 912) for the meta-analysis of the effects of randomized controlled trials (RCTs) of mindfulness-based interventions on meaning in life. Results Cross-sectional correlation between mindfulness and meaning was estimated to be .37, a moderate effect size. RCTs of mindfulness-based interventions had a moderate effect size on meaning (Hedge’s g = 0.53). Our systematic review indicated that the effect of mindfulness on meaning was mediated by decentering, authentic self-awareness, and attention to positive experience. Conclusions Overall, these findings showed the promise of applying mindfulness-based interventions to enhance meaning in life. However, more empirical studies with an active control group are required to establish the effects of mindfulness-based interventions above and beyond placebo effect.

Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo . As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as the inner stromal structure of a live mouse cornea, the fine structures inside the mouse pinna, and sweat ducts and Meissner’s corpuscle in the human fingertip skin—features that are otherwise obscured by speckle noise when using conventional OCT or OCT with current state of the art speckle reduction methods. Optical coherence tomography, a technique that can image inside tissue, is susceptible to speckle noise that limits its diagnostic potential. Here, Liba et al . show that speckle noise can be removed without effectively compromising resolution, revealing previously hidden small structures within tissue.

Lithium metal is an attractive anode material for rechargeable batteries, owing to its high theoretical specific capacity of 3,860 mAh g −1 . Despite extensive research efforts, there are still many fundamental challenges in using lithium metal in lithium-ion batteries. Most notably, critical information such as its nucleation and growth behaviour remains elusive. Here we explore the nucleation pattern of lithium on various metal substrates and unravel a substrate-dependent growth phenomenon that enables selective deposition of lithium metal. With the aid of binary phase diagrams, we find that no nucleation barriers are present for metals exhibiting a definite solubility in lithium, whereas appreciable nucleation barriers exist for metals with negligible solubility. We thereafter design a nanocapsule structure for lithium metal anodes consisting of hollow carbon spheres with nanoparticle seeds inside. During deposition, the lithium metal is found to predominantly grow inside the hollow carbon spheres. Such selective deposition and stable encapsulation of lithium metal eliminate dendrite formation and enable improved cycling, even in corrosive alkyl carbonate electrolytes, with 98% coulombic efficiency for more than 300 cycles. Uncontrolled lithium deposition during cycling is a major concern in the development of lithium-based batteries. Here, the authors analyse the lithium nucleation pattern on various metal substrates and demonstrate that lithium can be selectively deposited in a nanoseed inside hollow carbon spheres.

Meaning in life is an important element of psychological well-being. Intuitively, the search for meaning is associated with greater presence of meaning, but whether the relationship exists is met with mixed findings in the literature. The present studies aim to investigate the moderators of this relationship. Two studies, a one-month longitudinal study (N = 166, retention rate = 100%) and a six-month longitudinal study (N = 181, retention rate = 83%) were carried out. Participants completed measures on meaning in life, personality variables, and psychological needs in the baseline survey, and meaning in life in the follow-up survey. Multiple regression analysis showed that optimism, BIS, and psychological needs emerged to be significant moderators of the longitudinal relationship. Search for meaning at baseline was positively associated with presence of meaning at follow-up only for those with greater maladaptive traits. The search for meaning in adverse circumstances appears to be more effective than in benign conditions. Deficiency search is functional.

Electrochemical CO 2 reduction is a critical approach to reducing the globally accelerating CO 2 emission and generating value-added products. Despite great efforts to optimize catalyst activity and selectivity, facilitating the catalyst accessibility to high CO 2 concentrations while maintaining electrode durability remains a significant challenge. Here, we designed a catalytic system that mimics the alveolus structure in mammalian lungs with high gas permeability but very low water diffusibility, enabling an array of three-phase catalytic interfaces. Flexible, hydrophobic, nanoporous polyethylene membranes with high gas permeability were used to enable efficient CO 2 access and a high local alkalinity on the catalyst surface at different CO 2 flow rates. Such an alveolus-mimicking structure generates a high CO production Faradaic efficiency of 92% and excellent geometric current densities of CO production (25.5 mA cm −2 ) at −0.6 V versus the reversible hydrogen electrode, with a very thin catalyst thickness of 20−80 nm. The efficient design of electrochemical CO 2 reduction catalysts requires high CO 2 concentrations on the catalyst surface. Here, Cui and co-workers make use of flexible, hydrophobic, nanoporous polyethylene membranes with good gas permeability to design a catalytic set-up that mimics the alveolus structure in mammalian lungs, achieving high activity and selectivity to CO.

Rat sarcoma (Ras) GTPases regulate cell proliferation and survival through effector pathways including Raf-MAPK, and are the most frequently mutated genes in human cancer. Although it is well established that Ras activity requires binding to both GTP and the membrane, details of how Ras operates on the cell membrane to activate its effectors remain elusive. Efforts to target mutant Ras in human cancers to therapeutic benefit have also been largely unsuccessful. Here we show that Ras-GTP forms dimers to activate MAPK. We used quantitative photoactivated localization microscopy (PALM) to analyze the nanoscale spatial organization of PAmCherry1-tagged KRas 4B (hereafter referred to KRas) on the cell membrane under various signaling conditions. We found that at endogenous expression levels KRas forms dimers, and KRas ᴳ¹²ᴰ, a mutant that constitutively binds GTP, activates MAPK. Overexpression of KRas leads to formation of higher order Ras nanoclusters. Conversely, at lower expression levels, KRas ᴳ¹²ᴰ is monomeric and activates MAPK only when artificially dimerized. Moreover, dimerization and signaling of KRas are both dependent on an intact CAAX (C, cysteine; A, aliphatic; X, any amino acid) motif that is also known to mediate membrane localization. These results reveal a new, dimerization-dependent signaling mechanism of Ras, and suggest Ras dimers as a potential therapeutic target in mutant Ras-driven tumors. Significance Rat sarcoma (Ras) proteins play central roles in both normal and oncogenic signaling. Mechanisms of how Ras interacts with its effectors on the cell membrane, however, are still poorly understood, significantly hampering efforts to target this molecule in human cancer. Here we have used quantitative superresolution fluorescence microscopy in combination with carefully engineered biological systems to show that Ras dimers drive oncogenic signaling through the Raf-MAPK pathway. Our study suggests a new, dimer model of Ras-Raf signaling and the potential value of Ras dimers as a therapeutic target.