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Without neon, Las Vegas might still be a sleepy desert town in Nevada and Times Square merely another busy intersection in New York City. Transformed by the installation of these brightly colored signs, these destinations are now world-famous, representing the vibrant heart of popular culture. But for some, neon lighting represents the worst of commercialism. Energized by the conflicting love and hatred people have for neon, Flickering Light explores its technological and intellectual history, from the discovery of the noble gas in late nineteenth-century London to its fading popularity today. Christoph Ribbat follows writers, artists, and musicians-from cultural critic Theodor Adorno, British rock band the Verve, and artist Tracey Emin to Vladimir Nabokov, Langston Hughes, and American country singers-through the neon cities in Europe, America, and Asia, demonstrating how they turned these blinking lights and letters into metaphors of the modern era. He examines how gifted craftsmen carefully sculpted neon advertisements, introducing elegance to modern metropolises during neon's heyday between the wars followed by its subsequent popularity in Las Vegas during the 1950s and '60s. Ribbat ends with a melancholy discussion of neon's decline, describing how these glowing signs and installations came to be seen as dated and characteristic of run-down neighborhoods. From elaborate neon lighting displays to neglected diner signs with unlit letters, Flickering Light tells the engrossing story of how a glowing tube of gas took over the world-and faded almost as quickly as it arrived.

Xenon isotopic analysis shows that ancient pockets of water found in a mine in Timmins, Canada, have survived in the Earth’s crust for at least 1.5 billion years. Water from the deep past The deep continental crust contains water-filled fractures that can preserve a record of fluid chemistry and environmental conditions at the time of isolation. This paper reports noble gas isotopic compositions from bulk fracture fluids located 2.4 km below the surface in 2.7-billion-year-old rocks in the Timmins mine in Ontario, Canada. The isotope data indicate that some of these ancient pockets of water have remained isolated in the crust for between 1.5 and 2.64 billion years. The gas in this water — the oldest 'free fluid' ever found — is a mixture of hydrogen, helium, methane and nitrogen. The authors speculate that these ancient fluid environments may be capable of supporting life. Fluids trapped as inclusions within minerals can be billions of years old and preserve a record of the fluid chemistry and environment at the time of mineralization 1 , 2 , 3 . Aqueous fluids that have had a similar residence time at mineral interfaces and in fractures (fracture fluids) have not been previously identified. Expulsion of fracture fluids from basement systems with low connectivity occurs through deformation and fracturing of the brittle crust 4 . The fractal nature of this process must, at some scale, preserve pockets of interconnected fluid from the earliest crustal history. In one such system, 2.8 kilometres below the surface in a South African gold mine, extant chemoautotrophic microbes have been identified in fluids isolated from the photosphere on timescales of tens of millions of years 5 . Deep fracture fluids with similar chemistry have been found in a mine in the Timmins, Ontario, area of the Canadian Precambrian Shield. Here we show that excesses of 124 Xe, 126 Xe and 128 Xe in the Timmins mine fluids can be linked to xenon isotope changes in the ancient atmosphere 2 and used to calculate a minimum mean residence time for this fluid of about 1.5 billion years. Further evidence of an ancient fluid system is found in 129 Xe excesses that, owing to the absence of any identifiable mantle input, are probably sourced in sediments and extracted by fluid migration processes operating during or shortly after mineralization at around 2.64 billion years ago. We also provide closed-system radiogenic noble-gas ( 4 He, 21 Ne, 40 Ar, 136 Xe) residence times. Together, the different noble gases show that ancient pockets of water can survive the crustal fracturing process and remain in the crust for billions of years.

Evidence for the capture of nebular gases by planetary interiors would place important constraints on models of planet formation. These constraints include accretion timescales, thermal evolution, volatile compositions and planetary redox states 1 – 7 . Retention of nebular gases by planetary interiors also constrains the dynamics of outgassing and volatile loss associated with the assembly and ensuing evolution of terrestrial planets. But evidence for such gases in Earth’s interior remains controversial 8 – 14 . The ratio of the two primordial neon isotopes, 20 Ne/ 22 Ne, is significantly different for the three potential sources of Earth’s volatiles: nebular gas 15 , solar-wind-irradiated material 16 and CI chondrites 17 . Therefore, the 20 Ne/ 22 Ne ratio is a powerful tool for assessing the source of volatiles in Earth’s interior. Here we present neon isotope measurements from deep mantle plumes that reveal 20 Ne/ 22 Ne ratios of up to 13.03 ± 0.04 (2 standard deviations). These ratios are demonstrably higher than those for solar-wind-irradiated material and CI chondrites, requiring the presence of nebular neon in the deep mantle. Furthermore, we determine a 20 Ne/ 22 Ne ratio for the primordial plume mantle of 13.23 ± 0.22 (2 standard deviations), which is indistinguishable from the nebular ratio, providing robust evidence for a reservoir of nebular gas preserved in the deep mantle today. The acquisition of nebular gases requires planetary embryos to grow to sufficiently large mass before the dissipation of the protoplanetary disk. Our observations also indicate distinct 20 Ne/ 22 Ne ratios between deep mantle plumes and mid-ocean-ridge basalts, which is best explained by addition of a chondritic component to the shallower mantle during the main phase of Earth’s accretion and by subsequent recycling of seawater-derived neon in plate tectonic processes. The distinctive 20 Ne/ 22 Ne ratio in material thought to come from deep mantle plumes provides evidence for nebular gas as a source of volatiles in Earth’s interior.

The magnitude of global cooling during the Last Glacial Maximum (LGM, the coldest multimillennial interval of the last glacial period) is an important constraint for evaluating estimates of Earth’s climate sensitivity 1 , 2 . Reliable LGM temperatures come from high-latitude ice cores 3 , 4 , but substantial disagreement exists between proxy records in the low latitudes 1 , 5 – 8 , where quantitative low-elevation records on land are scarce. Filling this data gap, noble gases in ancient groundwater record past land surface temperatures through a direct physical relationship that is rooted in their temperature-dependent solubility in water 9 , 10 . Dissolved noble gases are suitable tracers of LGM temperature because of their complete insensitivity to biological and chemical processes and the ubiquity of LGM-aged groundwater around the globe 11 , 12 . However, although several individual noble gas studies have found substantial tropical LGM cooling 13 – 16 , they have used different methodologies and provide limited spatial coverage. Here we use noble gases in groundwater to show that the low-altitude, low-to-mid-latitude land surface (45 degrees south to 35 degrees north) cooled by 5.8 ± 0.6 degrees Celsius (mean ± 95% confidence interval) during the LGM. Our analysis includes four decades of groundwater noble gas data from six continents, along with new records from the tropics, all of which were interpreted using the same physical framework. Our land-based result broadly supports a recent reconstruction based on marine proxy data assimilation 1 that suggested greater climate sensitivity than previous estimates 5 – 7 . Analyses and modelling of noble gases in groundwater show that the mean annual surface temperatures of low-altitude, low-to-mid-latitude land masses were about 6 °C cooler during the Last Glacial Maximum than during the Late Holocene.

The phase behaviour of warm dense hydrogen−helium (H−He) mixtures affects our understanding of the evolution of Jupiter and Saturn and their interior structures 1 , 2 . For example, precipitation of He from a H−He atmosphere at about 1−10 megabar and a few thousand kelvin has been invoked to explain both the excess luminosity of Saturn 1 , 3 , and the depletion of He and neon (Ne) in Jupiter’s atmosphere as observed by the Galileo probe 4 , 5 . But despite its importance, H−He phase behaviour under relevant planetary conditions remains poorly constrained because it is challenging to determine computationally and because the extremes of temperature and pressure are difficult to reach experimentally. Here we report that appropriate temperatures and pressures can be reached through laser-driven shock compression of H 2 −He samples that have been pre-compressed in diamond-anvil cells. This allows us to probe the properties of H−He mixtures under Jovian interior conditions, revealing a region of immiscibility along the Hugoniot. A clear discontinuous change in sample reflectivity indicates that this region ends above 150 gigapascals at 10,200 kelvin and that a more subtle reflectivity change occurs above 93 gigapascals at 4,700 kelvin. Considering pressure–temperature profiles for Jupiter, these experimental immiscibility constraints for a near-protosolar mixture suggest that H−He phase separation affects a large fraction—we estimate about 15 per cent of the radius—of Jupiter’s interior. This finding provides microphysical support for Jupiter models that invoke a layered interior to explain Juno and Galileo spacecraft observations 1 , 4 , 6 – 8 . Hydrogen and helium mixtures can be compressed to the extreme temperature and pressure conditions found in the interior of Jupiter and Saturn, and the immiscibility revealed supports models of Jupiter that invoke a layered interior.

Earth and Venus part company The Mariner and Venera probes sent to Venus in the 1960s and 1970s revealed many differences between the venusian atmosphere and that on Earth. One of the hardest to account for is the preponderance of noble gases on Venus, in particular an argon-36 level 50 times higher than on Earth. A new theory tracks the cause of this difference to around 4.5 billion years ago, when Earth and Venus are thought to have grown as a result of collisions between several Mars-sized planets. Numerical simulations show that when a giant impact occurs, the presence of an ocean drastically increases the rate at which atmosphere is lost. On Earth, almost all the proto-atmosphere accrued during planet formation would have been stripped away during collisions. Venus, nearer the Sun, is unlikely to have had a major ocean, and its proto-atmosphere would have survived. The atmospheric compositions of Venus and Earth differ significantly, with the venusian atmosphere containing about 50 times as much 36 Ar as the atmosphere on Earth 1 . The different effects of the solar wind on planet-forming materials for Earth and Venus have been proposed to account for some of this difference in atmospheric composition 2 , 3 , but the cause of the compositional difference has not yet been fully resolved. Here we propose that the absence or presence of an ocean at the surface of a protoplanet during the giant impact phase could have determined its subsequent atmospheric amount and composition. Using numerical simulations, we demonstrate that the presence of an ocean significantly enhances the loss of atmosphere during a giant impact owing to two effects: evaporation of the ocean, and lower shock impedance of the ocean compared to the ground. Protoplanets near Earth's orbit are expected to have had oceans, whereas those near Venus’ orbit are not, and we therefore suggest that remnants of the noble-gas rich proto-atmosphere survived on Venus, but not on Earth. Our proposed mechanism explains differences in the atmospheric contents of argon, krypton and xenon on Venus and Earth, but most of the neon must have escaped from both planets’ atmospheres later to yield the observed ratio of neon to argon.

Shifts in reproductive timing are among the most commonly documented responses of organisms to global climate change. However, our knowledge of these responses is biased towards taxa that are easily observable and abundant in existing biodiversity data sets. Mammals are common subjects in reproductive biology, but mammalian phenology and its drivers in the wild remain poorly understood because many species are small, secretive, or too labor-intensive to monitor. We took an informatics-based approach to reconstructing breeding phenology in the widespread North American deer mouse (Peromyscus maniculatus) using individual-level reproductive observations from digitized museum specimens and field censuses spanning >100 yr and >45 degrees of latitude. We reconstructed female phenology in different regions and tested the importance of three environmental variables (photoperiod, temperature, precipitation) as breeding cues. Photoperiod and temperature were strong positive and negative breeding cues, respectively, whereas precipitation was not a significant predictor of breeding phenology. However, phenologies and the use of environmental cues varied substantially among regions, and we found evidence that these cueing repertoires are tuned to ecosystemspecific limiting conditions. Our results reiterate the importance of ecological context in optimizing reproduction and demonstrate how harmonization across biodiversity data resources allows new insight into phenology and its drivers in wild mammals.

Recent development in the synthesis and characterization of noble-gas compounds is reviewed, i.e., noble-gas chemistry reported in the last five years with emphasis on the publications issued after 2017. XeF2 is commercially available and has a wider practical application both in the laboratory use and in the industry. As a ligand it can coordinate to metal centers resulting in [M(XeF2)x]n+ salts. With strong Lewis acids, XeF2 acts as a fluoride ion donor forming [XeF]+ or [Xe2F3]+ salts. Latest examples are [Xe2F3][RuF6]·XeF2, [Xe2F3][RuF6] and [Xe2F3][IrF6]. Adducts NgF2·CrOF4 and NgF2·2CrOF4 (Ng = Xe, Kr) were synthesized and structurally characterized at low temperatures. The geometry of XeF6 was studied in solid argon and neon matrices. Xenon hexafluoride is a well-known fluoride ion donor forming various [XeF5]+ and [Xe2F11]+ salts. A large number of crystal structures of previously known or new [XeF5]+ and [Xe2F11]+ salts were reported, i.e., [Xe2F11][SbF6], [XeF5][SbF6], [XeF5][Sb2F11], [XeF5][BF4], [XeF5][TiF5], [XeF5]5[Ti10F45], [XeF5][Ti3F13], [XeF5]2[MnF6], [XeF5][MnF5], [XeF5]4[Mn8F36], [Xe2F11]2[SnF6], [Xe2F11]2[PbF6], [XeF5]4[Sn5F24], [XeF5][Xe2F11][CrVOF5]·2CrVIOF4, [XeF5]2[CrIVF6]·2CrVIOF4, [Xe2F11]2[CrIVF6], [XeF5]2[CrV2O2F8], [XeF5]2[CrV2O2F8]·2HF, [XeF5]2[CrV2O2F8]·2XeOF4, A[XeF5][SbF6]2 (A = Rb, Cs), Cs[XeF5][BixSb1-xF6]2 (x = ~0.37–0.39), NO2XeF5(SbF6)2, XeF5M(SbF6)3 (M = Ni, Mg, Zn, Co, Cu, Mn and Pd) and (XeF5)3[Hg(HF)]2(SbF6)7. Despite its extreme sensitivity, many new XeO3 adducts were synthesized, i.e., the 15-crown adduct of XeO3, adducts of XeO3 with triphenylphosphine oxide, dimethylsulfoxide and pyridine-N-oxide, and adducts between XeO3 and N-bases (pyridine and 4-dimethylaminopyridine). [Hg(KrF2)8][AsF6]2·2HF is a new example of a compound in which KrF2 serves as a ligand. Numerous new charged species of noble gases were reported (ArCH2+, ArOH+, [ArB3O4]+, [ArB3O5]+, [ArB4O6]+, [ArB5O7]+, [B12(CN)11Ne]−). Molecular ion HeH+ was finally detected in interstellar space. The discoveries of Na2He and ArNi at high pressure were reported. Bonding motifs in noble-gas compounds are briefly commented on in the last paragraph of this review.