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An updated and expanded data set that consists of 214 plagioclase-liquid equilibrium pairs from 40 experimental studies in the literature is used to recalibrate the thermodynamic model for the plagioclase-liquid hygrometer of Lange et al. (2009); the updated model is applicable to metaluminous and alkaline magmas. The model is based on the crystal-liquid exchange reaction between the anorthite (CaAl2Si2O8) and albite (NaAlSi3O8) components, and all available volumetric and calorimetric data for the pure end-member components are used in the revised model. The activities of the crystalline plagioclase components are taken from Holland and Powell (1992). Of the 214 experiments, 107 are hydrous and 107 are anhydrous. Four criteria were applied for inclusion of experiments in the final data set: (1) crystallinities <30%; (2) pure-H2O fluid saturated; (3) compositional totals (including H2O component) of 97-101% for hydrous quenched glasses and 98.5-101 for anhydrous quenched glasses; and (4) melt viscosities ≤5.2 log10 Pa·s. The final data set spans a wide range in liquid composition (45-80 wt% SiO2; 1-10 wt% Na2O+K2O), plagioclase composition (An17-95), temperature (750-1244°C), pressure (0-350 MPa), and H2O content (0-8.3 wt%). The water solubility model of Zhang et al. (2007) was applied to all hydrous experiments. The standard error estimate on the hygrometer model is 0.35 wt% H2O, and all liquid compositions are fitted equally well. Application of the model as a thermometer recovers temperatures to within ±12°, on average. Tests of the hygrometer on anhydrous piston-cylinder experiments in the literature, not included in the regression, show that the model is accurate at all pressures where plagioclase is stable. Applications of the hygrometer are made to natural rhyolites (Bishop Tuff, Katmai, and TobaTuff) with reported H2O analyses in quartz-hosted melt inclusions from the literature; the results show agreement. Applications of the hygrometer/thermometer are additionally made to natural rhyolites from Iceland and Glass Mountain, California. The updated model can be downloaded either as a program in Excel format or as a MatLab script from the Data Repository.

Machine vision technology is an interdisciplinary subject involving plenty of fields such as artificial intelligence, neurobiology, psychophysics, computer science, image processing and pattern recognition, etc. In recent years, with rapid development of the technology, machine vision recognition is widely used in many fields of detection and control. For thermo-hygrometers calibration, the manual operation method is used traditionally. This has proven to be a cumbersome, time-consuming, and error-prone activity, as there are lots of models and quantities of thermo-hygrometers to be calibrated. Therefore, an automatic thermo-hygrometers calibration system was developed by using vision recognition technology in combination with automatic movement control as well as a purposely structured database management software. It can complete the calibration and the verification task accurately, timely and efficiently. It has drastically reduced the workload, improved accuracy, and realized the automatic calibration of the thermo-hygrometers.

Compositions of plagioclase‐melt pairs are commonly used to constrain temperatures (T), dissolved water contents (H2O) and pressures (P) of pre‐eruptive magma storage and transport. However, previous plagioclase‐based thermometers, hygrometers, and barometers can have significant errors, leading to imprecise reconstructions of conditions during plagioclase growth. Here, we explore whether we can refine existing plagioclase‐based hygrothermobarometers with either plagioclase‐melt or melt‐only chemistry (±T/H2O), calibrated using random forest machine learning on experimental petrology data (n = 1,152). We find that both the plagioclase‐melt and melt‐only models return similar cross‐validation root‐mean‐square errors (RMSEs), as the melt holds most of the P‐T‐H2O information rather than the plagioclase. T/H2O‐dependent melt models have test set RMSEs of 25°C, 0.70 wt.% and 76 MPa for temperature, H2O content and pressure, respectively, while T/H2O‐independent models have RMSEs of 38°C, 0.97 wt.% and 91 MPa. The melt thermometer and hygrometer are applicable to a wide range of plagioclase‐bearing melts at temperatures between 664 and 1355°C, and with H2O concentrations up to 11.2 wt.%, while the melt barometer is suitable for pressures of ≤500 MPa. An updated plagioclase‐melt equilibrium model has also been calibrated, allowing the equilibrium anorthite content to be predicted with an error of 5.8 mol%. The new P‐T‐H2O‐An models were applied to matrix glasses and melt inclusions from the 1980 Mount St Helens (USA) and 2014–2015 Holuhraun (Iceland) eruptions, corroborating previous independent estimates and observations. Models are available at https://github.com/kyra‐cutler/Plag‐saturated‐melt‐P‐T‐H2O‐An, enabling assessment of plagioclase‐melt equilibrium and characterization of last‐equilibrated P‐T‐H2O conditions of plagioclase‐saturated magmas. Plain Language Summary Thermobarometry and hygrometry are common methods for reconstructing magma crystallization conditions (pressure (P), temperature (T) and dissolved water content (H2O)) prior to eruption. Plagioclase is a ubiquitous mineral found in a wide range of volcanic rocks and is often used to estimate P‐T‐H2O conditions. Here, we use machine learning‐based regression to calibrate new models, based on either plagioclase‐melt or melt‐only chemistry, to test whether we can improve the existing range of plagioclase‐based thermobarometers and hygrometers. We also develop an updated model to determine the equilibrium composition of a plagioclase crystal with a given normalized melt composition. We find that the plagioclase‐melt and melt‐only thermobarometers and hygrometers return very similar model errors due to the melt holding nearly all the P‐T‐H2O information. The models can be applied to a wide range of plagioclase‐bearing melts except for the barometer, which is only appropriate for upper crustal pressures of ≤500 MPa (≤13.8 km depth). Models are available at https://github.com/kyra‐cutler/Plag‐saturated‐melt‐P‐T‐H2O‐An, enabling assessment of plagioclase‐melt equilibrium and characterization of last‐equilibrated P‐T‐H2O conditions of plagioclase‐saturated magmas. Key Points Investigation into whether existing plagioclase‐based hygrothermobarometers can be refined using random forest machine learning The algorithm highlights that only melt composition is required to estimate intensive variables (P‐T‐H2O) of plagioclase‐saturated magmas New melt models show improvement in errors compared to thermodynamic‐based plagioclase‐melt hygrothermobarometers and equilibria models

Optical humidity sensors have evolved through decades of research and development, constantly adapting to new demands and challenges. The continuous growth is supported by the emergence of a variety of optical fibers and functional materials, in addition to the adaptation of different sensing mechanisms and optical techniques. This review attempts to cover the majority of optical humidity sensors reported to date, highlight trends in design and performance, and discuss the challenges of different applications.

The Fast Infrared Hygrometer (FIRH), employing open-path tunable diode laser absorption spectroscopy at the wavelengths near the 1364.6896 nm line, was adapted to perform contactless humidity measurements at the Turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T), a unique turbulent moist-air wind tunnel. The configuration of the setup allows for scanning from outside the walls of the wind tunnel and at various positions without the need for repeated optics adjustments. We identified three factors which significantly influence the measurement – self-broadening of the absorption line, interference in the glass windows and parasitic absorption in the ambient air outside the wind tunnel – and developed correction methods which satisfactorily account for these effects. The comparison between FIRH and a reference hygrometer (dew-point mirror MBW 973) indicated a good agreement within the expected errors across the wide range of water vapour concentration 1.0–6.1×1017 cm−3 (equivalent to dew-point temperature of −5.4 to +21 ∘C at the temperature of 23 ∘C). High temporal resolution (∼2 kHz) allowed for studying turbulent fluctuations in the course of intensive mixing of two air streams which had the same mean velocity but differed in temperature and humidity, also including the settings for which the mixture can be supersaturated. The obtained results contribute to improved understanding and interpretation of cloud formation studies conducted in LACIS-T by complementing the previous characterizations of turbulent velocity and temperature fields inside the wind tunnel.

The genesis of intermediate intrusions is highly controversial, and one of the hot topics is whether they represent frozen melts or cumulates in the evolution of magmatic systems. Distinguishing accumulation from crystallization melt differentiated along the liquid line of descent is the key issue. The Paleoproterozoic intermediate intrusions in southern North China Craton provide an excellent case to decipher this issue. Multiple lines of evidence, including mineral textures, geochemistry as well as alphaMELTS modeling, indicate disequilibrium between whole‐rock and minerals, with melt extraction occurring at temperatures of 760°–820°C and with 10–40 wt.% of trapped melts. Effective water storage, revealed by amphibole and clinopyroxene hygrometers, plays a crucial role in promoting crystal‐melt segregation in pluton‐sized reservoirs in the upper crust. This study demonstrates that the accumulation in intermediate magmas can be identified even without evident complementary initial and extracted melts and provides deep insights into the genesis of intermediate continental crust. Plain Language Summary The genesis of intermediate rocks has long been controversial since they are analogs of the average composition of continental upper crust. The key topic is whether intermediate rocks represent frozen melts of intermediate magmas or crystal residues after melt extraction in the evolution of felsic magmatic systems. Here we carried out a comprehensive study on the Paleoproterozoic intermediate intrusions in the southern North China Craton, which is considered to have recorded the process of crystal accumulation and melt segregation in the shallow crust. Upon mineral texture, geochronologic, whole‐rock and mineral geochemical, and thermodynamic investigation, we propose that crystal accumulation and crystal‐melt segregation processes can be identified in intermediate magmas with the melt extraction temperatures and proportions of trapped melts recorded by zircon trace elements. Amphibole and clinopyroxene hygrometers revealed high water content of the melts, which likely decreased the viscosity of melts and facilitated effective cumulate‐melt segregation. This study provides a powerful reference to see through the accumulation in intermediate magmas, record the processes of crystal‐melt segregation, and definitively resolve the debate concerning the genesis of intermediate intrusions. Key Points Crystal accumulation in intermediate magmas can be identified by mineral texture and geochemistry The effective water storage system in the reservoirs is key to promoting crystal‐melt segregation Crystal‐melt segregation and accumulation are fundamental processes to form evolved continental upper crust

Integration of low-cost air quality sensors with the internet of things (IoT) has become a feasible approach towards the development of smart cities. Several studies have assessed the performance of low-cost air quality sensors by comparing their measurements with reference instruments. We examined the performance of a low-cost IoT particulate matter (PM 10 and PM 2.5 ) sensor in the urban environment of Santiago, Chile. The prototype was assembled from a PM 10 –PM 2.5 sensor (SDS011), a temperature and relative humidity sensor (BME280) and an IoT board (ESP8266/Node MCU). Field tests were conducted at three regulatory monitoring stations during the 2018 austral winter and spring seasons. The sensors at each site were operated in parallel with continuous reference air quality monitors (BAM 1020 and TEOM 1400) and a filter-based sampler (Partisol 2000i). Variability between sensor units ( n  = 7) and the correlation between the sensor and reference instruments were examined. Moderate inter-unit variability was observed between sensors for PM 2.5 (normalized root-mean-square error 9–24%) and PM 10 (10–37%). The correlations between the 1-h average concentrations reported by the sensors and continuous monitors were higher for PM 2.5 ( R 2 0.47–0.86) than PM 10 (0.24–0.56). The correlations ( R 2 ) between the 24-h PM 2.5 averages from the sensors and reference instruments were 0.63–0.87 for continuous monitoring and 0.69–0.93 for filter-based samplers. Correlation analysis revealed that sensors tended to overestimate PM concentrations in high relative humidity (RH > 75%) and underestimate when RH was below 50%. Overall, the prototype evaluated exhibited adequate performance and may be potentially suitable for monitoring daily PM 2.5 averages after correcting for RH.

This study presents a new methodology to derive adjusted water vapour (H2O) climatologies for the extra-tropical upper troposphere and lowermost stratosphere (UT/LMS) from regular measurements on board passenger aircraft between 1994 and 2022 within the IAGOS (In-service Aircraft for a Global Observing System) research infrastructure. A synthesis of mean H2O is performed by sampling air mass bins of similar origin and thermodynamic conditions relative to the tropopause between a dataset from 60 000 flights employing the IAGOS-MOZAIC (Measurement of Ozone by AIRBUS In-Service Aircraft) and IAGOS-CORE capacitive hygrometer (ICH) and a dataset of 500 flights using the more sophisticated IAGOS-CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) hygrometer. The analysis is, in combination with ECMWF ERA5 meteorological data, accomplished for the extra-tropical Northern Hemisphere, where the datasets have the largest common coverage. We find very good agreement in the UT but a systematic positive humidity bias in the ICH measurements for the LMS. To account for this bias, mean H2O of the ICH is adjusted to the IAGOS-CARIBIC measurements based on a new mapping and adjustment approach. After applying this new method, the LMS H2O measurements are in good agreement between all investigated platforms. The extensive H2O dataset from the compact IAGOS sensor can now be used to produce highly resolved H2O climatologies for the climatically sensitive LMS region.

Currently, lightweight wearable energy storage devices are in great demand owing to their use in wearable electronics and energy-efficient electric vehicles. Freestanding carbon nanofibers replace the need for metal substrates while providing a rapid electrical network owing to their excellent electrical properties. Bimetallic oxides with multivalent oxidation states facilitate the rapid transfer of electrolytic ions owing to efficient Faradaic reactions, thereby enhancing the overall energy storage capability. In this study, CoOx@CNF was derived from ZIF-67 (zeolitic-imidazolate framework) @PAN-2MI fibers that were stabilized in air at 280°C and then annealed in argon at 900°C. Subsequently, Co was seeded on the annealed CoOx@CNF and subjected to a hydrothermal process in sodium molybdate dihydrate solution to grow CoMoO4 nanosheets, eventually forming bimetallic CoMoO4@CNF. The concentration of sodium molybdate solution was varied to determine the optimal growth conditions for CoMoO4 nanosheets. The energy density of the optimal bimetallic CoMoO4@CNF sample was 166.5 μWh cm-2 at a power density of 200 μW cm-2; this represented a nearly twofold increase compared to that of the single metallic CoOx@CNF. Powering humidity sensors using only one CoMoO4@CNF supercapacitor was demonstrated. The optimal sample remained stable during long-term galvanostatic charge and discharge cycles (Ncyc=30,000) and retained 100% of its specific capacitance.