Prolonged Air Exposure Research Articles

Enhancing Performance and Stability of Perovskite Solar Cells with a Novel Formamidine Group Additive.

Perovskite materials, particularly FAPbI3, have emerged as promising candidates for solar energy conversion applications. However, these materials are plagued by well-known defects and suboptimal film quality. Enhancing crystallinity and minimizing defect density are therefore essential steps in the development of high-performance perovskite solar cells. In this study, 1H-Pyrazole-1-carboximidamide hydrochloride (PCH) is introduced into FAPbI3 perovskite films. The molecular structure of PCH features a pyrazole ring bonded to formamidine (FA). The FA moiety of PCH facilitated the incorporation of this additive into the film lattice, while the negatively charged pyrazole ring effectively passivated positively charged iodine vacancies. The presence of PCH led to the fabrication of an FAPbI3 device with improved crystallinity, a smoother surface, and reduced defect density, resulting in enhanced Voc and fill factor. A record power conversion efficiency of 24.62% is achieved, along with exceptional stability under prolonged air exposure and thermal stress. The findings highlight the efficacy of PCH as a novel additive for the development of high-performance perovskite solar cells.

K-Rich Spinel Interface of Air-Stable Layered Oxide Cathodes for Potassium-Ion Batteries.

Potassium-containing transition metal layered oxides (KxTmO2), although possessing high energy density and suitable operating voltage, suffer from severe hygroscopic properties due to their two dimensional (2D)layered structure. Their air sensitivity compromises structural stability during prolonged air exposure, therefore increasing the cost. The common sense for designing air-stable layered cathode materials is to avoid contact with H2Omolecules. In this study, it is surprisingly found that P3-type KxTmO2 forms an ultra-thin, potassium-rich spinel phase wrapping layer after simply water immersion, remarkedly reduces the reaction activity of the material's surface with air. Combined with Density Function Theory (DFT) calculations, this spinel phase is found to be able to effectively withstand air deterioration and preserving the crystal structure. Consequently, the water-treated material, when exposed to air, can largely maintain its good electrochemical performance, with capacity retention up to 99.15% compared to the fresh samples. Such an in situ surface phase transformation mechanism is also corroborated in other KxTmO2, underscoring its effectiveness in enhancing the air stability of P3-type layered oxides for K+ storage.

Impurity Level-Induced Broadband Photoelectric Response in Wide-Bandgap Semiconductor SrSnO3.

Broadband spectrum detectors exhibit great promise in fields such as multispectral imaging and optical communications. Despite significant progress, challenges like materials instability in such devices, complex manufacturing process, and high cost still hinder their further application. Here, we present a method that achieves broadband spectral detection by impurity-level in SrSnO3. We report over 500 mA/W photoresponsivity at 275 nm (ultraviolet C solar-bind) and 367 nm (ultraviolet A) and ∼60 mA/W photoresponsivity at 532 and 700 nm (visible) with a voltage bias of -5 V. Further transport and photoluminescence results reveal a new phase transition at 88 K, which would significantly affect the impurity level of the La-doped SrSnO3 film, indicating that the broadband response attributes to the impurity levels and mutual interactions. Additionally, the photodetector demonstrates excellent robustness and stability under repeated tests and prolonged exposure in air. These findings show the potential of SrSnO3 as a material for photodetectors and propose a method to achieve broadband spectrum detection, creating new possibility for the development of single-phase, low-cost, simple structure, and high-efficiency photodetectors.

3M™ Defib-Pads as a Reusable Alternative to Commercial Ultrasound Gel in Resource-Limited Settings.

With point-of-care ultrasound (POCUS) use in austere environments comes the challenge of having an ever-available coupling medium for image generation. Commercial gel has numerous drawbacks that can limit its utility in these settings, and no studies have evaluated the potential for a reusable coupling medium. This study aimed to determine whether 3M™ Defib-Pads could be utilized as a reusable alternative to commercial gel for image generation in resource-limited settings. A descriptive, cross-sectional survey of Canadian physicians with POCUS interest was conducted to evaluate the interpretability of various POCUS images in a blinded fashion. Three anatomic regions (cardiac, abdominal, and nerve) were utilized, and image generation from the commercial gel and 7 Defib-Pad conditions were evaluated. These included pads that were 1) newly opened, 2) dirtied then rinsed, 3) air dried, 4) rinsed after being air dried, 5) frozen then thawed, 6) used in double thickness, and 7) used with a probe cover. Compared to commercial gel, 3M™ Defib-Pads performed similarly, with adequate image interpretability of up to 100% in some conditions. The exception was pads that had prolonged air exposure, which produced images that were never interpretable. However, subsequent rinsing of these pads with water resulted in restored image generation. 3M™ Defib-Pads were found to produce interpretable POCUS images under multiple environmental stressors and with different modalities of use, suggesting that 3M™ Defib-Pads can perform as a reusable gel alternative in resource-limited settings.

Cold Habituation Does Not Alter Thermal Responses or Manual Dexterity During Prolonged Cold Air Exposure

Background: Habituation is a pattern of cold acclimatization characterized by attenuated cold defense responses, including a reduction in peripheral vasoconstriction and subsequent increase in skin temperature (TSk) as well as a decrease in shivering thermogenesis. Habituation is achieved through repeated reductions in TSk, rather than deep body core temperature (TC), via exposure to prolonged cold air or brief cold-water immersion. Due to improvements in TSk, enhanced manual dexterity and peripheral cold injury risk reduction are purported benefits of cold habituation. Warfighters frequently operate in cold climates and experience decrements in manual dexterity and strength. These functional losses can negatively impact mission critical tasks and training exercises; however, the effectiveness of cold habituation as a potential countermeasure to alleviate the deleterious effects of prolonged cold exposure on peripheral temperatures, thermal comfort, and hand function is unclear. Purpose: To evaluate the influence of eight consecutive cold air exposures on the thermal (TC and TSk), perceptual (thermal comfort and sensation), and functional (manual dexterity and strength) responses to cold air. We hypothesized that TSk would be higher and perceptual responses and manual dexterity improved, following repeated cold exposure. Methods: Eight young adults (6 M/1 F/1 FTM; 21 ± 2 years; %BF 24.5 ± 7.0) underwent a 2-h cold air exposure (8 °C, ~50% RH) on 8 consecutive days wearing minimal clothing. On Day 0 (baseline exposure ~1 week prior) and Days 1 and 8 of repeated exposure, TC was recorded continuously via a telemetry pill used as a rectal suppository. Extremity (Thand and Tfinger) and mean weighted TSk (MWTSk) from 8 skin sites were recorded continuously. Thermal comfort (TC) and thermal sensation (TS) were recorded at 20 min intervals. Expired gases were collected at 20 min intervals and used to calculate metabolic heat production (MHP). Manual dexterity was assessed using the Purdue Pegboard and Minnesota Manual Dexterity Test (MMDT), and hand strength were measured before and at the end of cold exposure. Results: TC changed across time ( p < 0.05) but did not differ between days ( p > 0.05). MWTSk, Thand, and Tfinger decreased across time ( p < 0.05) but also did not differ between days ( p > 0.05). Mean and minimum whole-body TS and TC were not different between days ( p > 0.05). MHP increased across time ( p < 0.05) but did not differ between days ( p > 0.05). Purdue Pegboard, MMDT task performance, and hand strength did not differ between days ( p > 0.05). Conclusion: Eight consecutive days of cold air exposure does not augment extremity skin temperature, thermal comfort, or manual performance during prolonged cold conditions. Supported by U.S. Army Medical Research and Development Command, Military Operational Medicine Research Program; author views not offcial US Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The fate of graphene on copper: Intercalation / de-intercalation processes and the role of silicon

Intercalation and de-intercalation processes below graphene (g) grown by chemical vapor deposition (CVD) on Cu foils (g/Cu) were investigated in a combined low-energy electron microscopy and X-ray photoemission electron microscopy study. Exposure of g/Cu to air induces oxygen and water intercalation which can be removed by annealing in vacuum leading to clean and well-ordered graphene on Cu. However, prolonged air exposure leads to intercalation of large amounts of oxygen, most likely inducing the formation of copper oxides. If sufficient intercalated oxygen remains at the interface when exceeding 320 °C, graphene is oxidized and burned off. Cu foils can be loaded with silicon on purpose during foil pre-treatment or accidently during long growth time when applying high temperatures at elevated H2 pressure inducing the reactive removal of Si species from the quartz reactor wall. Due to the dissolution of Si in the Cu bulk, the Si surface concentration remains below detection limit and graphene of equal crystalline quality is grown as if the Cu foil was silicon-free. However, oxygen intercalation underneath graphene on Si-containing Cu foils can induce Si segregation towards the surface and formation of intercalated silica without attacking the covering graphene. Even at high temperatures, segregating Si acts as oxygen scavenger so that graphene resists oxidation. The observed effect explains the usefulness of certain synthesis protocols and paves the way towards large-scale fabrication of electronically decoupled graphene. The effect can be used to immobilize adsorbing oxygen at the interface and image the initial steps of intercalation below graphene in-situ.

Evolving surface wettability in laser-powder bed fusion printed metal parts

This study presents an early-stage investigation of the evolving surface wettability of metal parts fabricated using laser powder bed fusion (L-PBF). Various printing strategies, surface orientations, and post-processing methods were evaluated to determine their influence on wettability. Results showed that the wetting properties of AlSi10Mg printed parts were initially superhydrophilic but transitioned to slightly hydrophilic after prolonged air exposure. Additionally, downskin surfaces exhibited higher roughness due to the presence of fused satellite particles. These findings underscore the inherent instability of wetting behavior in metal alloys produced by L-PBF and highlight the need for further exploration of postprocessing techniques to achieve consistent surface wettability.

Assessing the Potential of Adenosine and L-Theanine as Metabolic Suppressants for Improving Shipping of the New Zealand Scampi (Metanephrops challengeri)

Live crustaceans, especially lobsters, crabs, and shrimp, fetch premium prices in many international seafood markets, especially in parts of Asia. To access these market opportunities, live crustaceans frequently need to be transported over long distances, which can involve prolonged air exposure resulting in elevated stress and increased morbidity and mortality. Interventions which deliver metabolic suppression to live crustaceans during their transport have the potential to improve outcomes from live shipping. In this study, the administration of adenosine (Ado) and L-theanine (L-th) were assessed for metabolic suppression in the New Zealand scampi, Metanephrops challengeri, a deep sea lobster which is highly prized as seafood, and with excellent prospects for supply into premium live seafood markets. The administration to scampi of Ado and L-th in isolation or as a mixture (Ado/L-th), caused a significant decrease in heart rate (HR) with a lasting effect for the 4 hr experimental period. However, this depression of HR did not translate into a systemic downregulation of metabolism, as measured by the key metabolites, i.e., glycogen utilization and the accumulation of lactate and ammonia. The lack of systematic metabolic downregulation would preclude the potential use of Ado and L-th for commercial application in live shipping of crustaceans.

Ditopic ligand effects on solution structure and redox chemistry in discrete [Cu12S6] clusters with labile Cu-S bonds.

Copper chalcogenide nanoclusters (Cu-S/Se/Te NCs) are a broad and diverse class of atomically precise nanomaterials that have historically been studied for potential applications in luminescent devices and sensors, and for their beautiful, mineral-like crystal structures. By the "cluster-surface" analogy, Cu-S/Se NCs are prime candidates for the development of nanoscale multimetallic catalysts with atomic precision. However, the majority of studies conducted to date have focused exclusively on their solid-state structures and physical properties, leaving open questions as to their solution stability, dynamics, and reactivity. Herein, we report the first detailed interrogation of solution structure, dynamics, electrochemistry, and decomposition of Cu-S NCs. Specifically, we report the detailed NMR spectroscopy, diffusion-ordered spectroscopy, MALDI mass spectrometry, electrochemical and stoichiometric redox reactivity studies, and DFT studies of a series of [Cu12S6] clusters with labile Cu-S bonds supported by monodentate phosphines and ditopic bis(diphenylphosphino)alkane ligands PPh2R (R = Et, -(CH2)5-, -(CH2)8-). We find that the ligand binding topology dictates the extent of speciation in solution, with complete stability being afforded by the longer octane chelate in dppo (1,8-bis(diphenylphosphino)octane) according to 1H and DOSY NMR and MALDI-MS studies. Furthermore, a combined electrochemical and computational investigation of [Cu12S6(dppo)4] reveals that the intact [Cu12S6] core undergoes a quasireversible one-electron oxidation at mild applied potentials ([Cu12S6]0/+: -0.50 V vs. Fc0/+). In contrast, prolonged air exposure or treatment with chemical oxidants results in cluster degradation with S atom extrusion as phosphine sulfide byproducts. This work adds critical new dimensions to the stabilization and study of atomically precise metal chalcogenide NCs with labile M-S/Se bonds, and demonstrates both progress and challenges in controlling the solution behaviour and redox chemistry of phosphine-supported copper chalcogenide nanoclusters.

Changes in chemical composition and fermentation profile in silages from rehydrated grains of maize hybrids during prolonged air exposure

Most studies investigated the effects of air exposure during the ensiling of whole maize silage and high-moisture maize grains on the chemical composition and fermentation profile, but not of rehydrated grain. The aim of the present study was to investigate the effect of the hybrid and the duration of air exposure on the pH and the content of moisture, main nutrients, fermentation products and nitrogen fractions in silages from three commercial maize hybrids. The grains were rehydrated to 32 % of moisture and ensiled for 63 days with the addition of an inoculant (BIO-SIL®, Dr Pieper Technologie und Produktentwicklung GmbH). After opening, the silages were stored at room temperature for 10 days and samples were taken after 0, 1, 3, 5 and 10 days of air exposure. With increasing duration of air exposure, the content of moisture, lactic and acetic acid and ethanol decreased, while the pH value and the content of water-soluble carbohydrates and ammonia increased. The hybrid affected all the determined properties of the silages except the pH and the ethanol content. There were distinct differences in the contents of moisture, total sugars, water-soluble carbohydrates, lactic, acetic, propionic and isobutyric acids, methanol and ammonia, suggesting that some hybrids may be more susceptible to aerobic spoilage. The majority of the properties remained similar until the fifth day of air exposure, suggesting that the silages of all three hybrids were stable during this period. The only property that increased immediately after air exposure was the content of nitrogen fractions suggesting that proteolysis was occurring, even though pH and lactic acid content remained unchanged. Overall, the results of the study indicate that the behaviour of rehydrated maize silage after exposure to air should be taken into account when selecting maize hybrids.

Low coordinate Zn(II) organocations bearing extremely bulky NHC ligands: structural features, air-/water-tolerance and use in hydrosilylation and hydrogenation catalysis.

This work details the synthesis and characterization of low-coordinate Zn(II)-based organocations [(NHC)Zn(R)]+ incorporating extremely bulky NHCs [ITr] and [IAd] ([ITr] = ([ITr] = [(HCNCPh3)2C:]; [IAd] = [(HCNAd)2C:], Ad = adamantyl)). Their structural features and particularities are thoroughly assessed as well as their air and water tolerance. Neutral ITr and IAd adducts [(ITr)Zn(R)2] (1, R = Me; 2, R = Et) and [(IAd)Zn(R)2] (3, R = Me; 4, R = Et) were synthesized by reaction of carbene [ITr] or [IAd] with a stoichiometric amount of [ZnR2] and isolated in good yields. Despite the steric bulk of [ITr] and [IAd], neutral compounds 1-4 are robust and the solid state structure of adduct 3 was established through X-ray crystallographic studies as a trigonal monomer Zn(II) species. Adducts 1-4 may readily be ionized by [Ph3C][B(C6F5)4] to afford two-coordinate Zn(II) alkyl cations [(ITr)Zn(Me)]+ ([5]+) and [(ITr)Zn(Et)]+ ([6]+), [(IAd)Zn(Me)]+ ([7]+) and [(IAd)Zn(Me)]+ ([8]+), all isolated in high yields (>80%) as [B(C6F5)4]- salts, which were fully characterized. Remarkably, cation [(ITr)Zn(C6F5)]+ ([9]+), prepared by reaction of [5][B(C6F5)4] with [B(C6F5)3], features π-arene interactions with the electrophilic Zn(II), as deduced from solid state data and further completed by DFT-estimated non-covalent interactions (NCI), indicating that [ITr] may provide substantial steric and electrostatic stabilization. The latter certainly explains the remarkable stability of [(ITr)Zn(C6F5)]+ ([9]+) towards hydrolysis at RT, as it only coordinates H2O to afford an unprecedented stable Zn-OH2 organocation [10]+. Also noteworthy, H2O coordination is reversible allowing recovery of [(ITr)Zn(C6F5)]+ cation, even after prolonged air exposure. Yet, controlled hydrolysis of [(ITr)Zn(C6F5)]+ may occur upon heating with selective protonolysis of the Zn-C6F5 bond to afford structurally characterized dication [(ITr)Zn(OH)]22+ [11]2+. Interestingly, despite steric hindrance, the air-/water-tolerant cation [(ITr)Zn(C6F5)]+ is an effective CO2 hydrosilylation catalyst, and was also shown to mediate imine hydrogenation catalysis.

Predicting survival time for cold exposure by thermoregulation modeling

BackgroundExtreme temperatures are becoming increasingly common due to global warming. Extreme cold and heat events lead to an increase in mortality rates. More deaths occur in cold weather as a result of hypothermia. However, the change progress of body core temperature and the survival time during cold exposure has yet to be extensively studied. ObjectivesTo establish a mathematical thermoregulatory model for prolonged cold air exposure and to propose a method for predicting survival time under sedentary conditions. MethodsWe extended the classical multi-segment multi-node human thermoregulatory model by considering the effects of thermoregulatory fatigue on shivering and vasoconstriction based on the variable setpoint theory. The core threshold temperatures and the sensitivity of the responses decreased with the degree of fatigue (fa). The model was then used to systematically examine the effects of environmental parameters on the time course of body core temperature in the development of fatal hypothermia. A new wind chill index was constructed based on the simulated data of our thermoregulatory model to estimate the survival time. ResultsOur extended thermoregulatory model predicted that during prolonged cold air exposures, body core temperature would decrease in three distinct stages: an initial decrease due to uncompensated cooling load, an equilibrium plateau due to shivering, and a final rapid drop due to thermoregulatory fatigue. Fatal hypothermia occurred at the third stage due to impaired shivering and vasoconstriction caused by fatigue. Lower air temperature and higher air speed can accelerate the occurrence of hypothermia. We proposed a predictive equation for survival time, i.e., the maximum endurance time before fatal hypothermia occurs, which is an exponential function of the wind chill index, and the newly defined wind chill index considers the contribution from both air temperature and air speed. ConclusionsWe suggest a new thermoregulatory model to predict the fatal hypothermia due to thermoregulatory fatigue during cold air exposure. We proposed a survival time chart based on a new wind chill index, which can be used to alert the early risk of fatal hypothermia during extreme cold events.

Mass animal sacrifice at casas del Turuñuelo (Guareña, Spain): A unique Tartessian (Iron Age) site in the southwest of the Iberian Peninsula.

Zooarchaeological analyses of the skeletal remains of 52 animals unearthed in the courtyard of an Iron Age Tartessian building known as Casas del Turuñuelo (Badajoz, Spain) shed light on a massive sacrifice forming part of a series of rituals linked to the site's last period of activity and final abandonment. The rites took place towards the end of the 5th century BCE when both the building (intentionally destroyed) and the sacrificed animals were intentionally buried under a tumulus 90 m in diameter and 6 m high. The main objective of the zooarchaeological and microstratigraphic analyses was to determine the phasing of the sacrificial depositions. Evidence gathered from taphonomic assessments and a series of radiocarbon datings indicate that the sacrifices fall into three consecutive phases spanning several years. The findings of the zooarchaeological analyses clearly point to a selection of equid and cattle males. Adult equids predominate (MNI = 41) followed by adult and sub-adult cattle (MNI = 6). Pigs, in turn, are only represented by a few adults and sub-adult females (MNI = 4). Among the animals is a single dog of undetermined sex between 3 and 4 years of age. The fact that the animals are mostly adults discards the likelihood that they died from natural causes or an epidemic. In addition, the scenographic deposition of certain equids in pairs, as well as evidence of the burning of plant offerings, suggest an intentional ritualistic sacrifice. Nine of the initial depositions of Phase 1 in the SE quadrant were scattered and certain of their bones bear marks characteristic of both prolonged open air exposure and scavengers. Another 31 animals from Phases 1 and 2 are represented by almost complete, articulated skeletons, indicating they were promptly covered. Phase 3, by contrast, reveals both almost complete and partial animals bearing clear signs of processing for human consumption. This study thus sheds light on both the sequence of the animal sacrifices and the protocols linked to rites accompanied by the celebration of banquets. Certain features associated with the sealing of this building under a tumulus offer evidence of the decline of the Tartessian Culture. This study thus advances notions serving to contextualize ritual animal sacrifices in the framework of practice observed at other Iron Age sites in the Iberian Peninsula and elsewhere throughout Europe.

Thermal- and air- stability of the compositional variants of van der Waals Pt-Telluride thin films probed by high resolution photoemission spectroscopy

The Pt-Te compositional phase diagram consists of at least three different compositional line phases (PtTe2, Pt3Te4, and Pt2Te2) that can be described as layered van der Waals materials. This presents challenges in controlling the composition of ultrathin Pt-telluride 2D materials by physical vapor deposition methods. Here we show by temperature programmed synchrotron photoemission spectroscopy that the different phases have varying thermal stability in vacuum. This enables the synthesis of these materials by preparation of PtTe2 films at low growth temperatures and subsequent vacuum annealing to ∼ 350 °C for Pt3Te4, or ∼ 400 °C for Pt2Te2. Such prepared phases are characterized by high resolution core level spectroscopy to provide reference spectra for these materials. Moreover, the chemical stability of these materials was tested by exposure to oxygen and air. Even after prolonged air exposure only the surface Te layer was modified by oxygen chemical bonds that caused a 3-eV shift to higher binding energy of the Te-3d core levels. However, these oxygen species could be desorbed by vacuum annealing at 280 °C and pristine Pt-telluride samples can be re-established. This shows the excellent chemical stability of these materials, important for practical applications.

Out of water in the dark: Plasticity in visual structures and function in an amphibious fish

Many fishes encounter periods of prolonged darkness within their lifetime, yet the consequences for the visual system are poorly understood. We used an amphibious fish (Kryptolebias marmoratus) that occupies dark terrestrial environments during seasonal droughts to test whether exposure to prolonged darkness diminishes visual performance owing to reduced optic tectum (OT) size and/or neurogenesis. We performed a 3-week acclimation with a 2 2 factorial design, in which fish were either acclimated to a 12 h:12 h or 0 h:24 h light:dark photoperiod in water or in air. We found that water-exposed fish had poorer visual acuity when acclimated to the dark, while air-acclimated fish had poorer visual acuity regardless of photoperiod. The ability of K. marmoratus to capture aerial prey from water followed a similar trend, suggesting that good vision is important for hunting effectively. Changes in visual acuity did not result from changes in OT size, but air-acclimated fish had 37% fewer proliferating cells in the OT than water-acclimated fish. AsK. marmoratus are unable to eat on land, reducing cell proliferation in the OT may serve as a mechanism to reduce maintenance costs associated with the visual system. Overall, we suggest that prolonged darkness and air exposure can impair vision in K. marmoratus, and that changes in visual performance may be mediated, in part, by OT neurogenesis. More broadly, we show that plastic changes to the visual system of fishes can have potential consequences for organismal performance and fitness.

Superior anti-impurity gas poisoning ability and hydrogen storage properties of Ti–Cr alloy by introducing zirconium as additive

In this work, the anti-impurity gas poisoning ability and hydrogen storage properties of Ti–Cr alloy by introducing zirconium as additive have been investigated. The results showed that all alloys had C14-type main phase and Ti minor phase. The lattice parameter a, c and cell volume of the C14-type phase rose as Zr content increased. Furthermore, after introducing Zr, all alloys could absorb hydrogen immediately without any prior heat treatment or hydrogen exposure with/without prolonged air exposure. The maximum hydrogen storage capacity and the average effective hydrogen storage capacity of TiCr2 alloy also increased with Zr content. The cycle properties of all alloys with/without prolonged air exposure were also discussed. The results showed that all alloys had good cycle stability even if the alloys were exposed to the air for 2 days. The above results suggested that the addition of Zr had a positive effect on improving the hydrogen storage properties and anti-impurity gas poisoning properties of TiCr2 alloy. Finally, the mechanisms of first hydrogenation kinetic of all alloys with/without prolonged air exposure were also investigated by using the rate limiting step.

Effect of Air Exposure on the Acid–Base Balance of Hemolymph in Akoya Pearl Oyster Pinctada fucata martensii

The hemolymph acid–base status of Akoya pearl oyster Pinctada fucata martensii exposed to air at 20°C was investigated. Air-exposed Akoya pearl oyster showed a decrease in hemolymph pH from 7.568 to 6.825 after 24 h. The hemolymph total CO2 concentration increased from 2.25 mM/L to 4.50 mM/L during 24 h of air exposure. The hemolymph CO2 partial pressure (Pco2) was calculated by rearranging the Henderson–Hasselbalch equation. The hemolymph Pco2 increased from 1.0 torr to 14.8 torr, and bicarbonate ion concentration increased from 2.21 mM/L to 3.91 mM/L during 24 h of air exposure. The hemolymph calcium ion concentration ([Ca2+]) increased from 9.4 mM/L to 12.8 mM/L. These results indicated that Akoya pearl oysters showed hemolymph acidosis with partial metabolic compensation by mobilization of bicarbonate from the shell valve during prolonged air exposure. Immersion in seawater for between 4 h and 24 h decreased the effect of air exposure on hemolymph acid–base status, except for [Ca2+]. The hemolymph [Ca2+] of immersed Akoya pearl oysters was slightly higher than the initial level upon air exposure although hemolymph [Ca2+] had already decreased after immersion in seawater for 4 h and 24 h. The hemolymph acid–base balance of immersed Akoya pearl oysters recovered to the initial level after 4–24 h, even if the animals were exposed to the air for a prolonged time (24 h).

The Influence of Spontaneous Oxidative Conversion on the Characteristics of Lead‐Free Halide Perovskite CsSn(IxBr1−x)3 and on the Performance of Perovskite Light‐Emitting Diodes

AbstractIn this study, lead‐free perovskite CsSn(IxBr1−x)3 films with photoluminescence emission wavelengths from 677 to 887 nm are prepared. The influence of air exposure on their characteristics is also investigated. It is found that CsSnI3 can be transformed to Cs2SnI6 upon increasing the air exposure time. The decomposition and oxidation mechanisms are confirmed by the X‐ray diffraction pattern due to the presence of CsI peak. It is observed that devices based on the CsSn(IxBr1−x)3 film with increased Br− ratio and the CsSnI3 film with prolonged air exposure time show inferior performance. These results are mainly attributed to the highest occupied molecular orbital levels of CsSn(IxBr1−x)3 and Cs2SnI6. Defect density of state and binding energy of these materials are also investigated and reported in this study.

Thermal Atomic Layer Deposition of Yttrium Oxide Films and Their Properties in Anticorrosion and Water Repellent Coating Applications

The thermal atomic layer deposition (ThALD) of yttrium oxide (Y2O3) was developed using the newly designed, liquid precursor, Y(EtCp)2(iPr2-amd), as the yttrium source in combination with different oxygen sources, such as ozone, water and even molecular oxygen. Saturation was observed for the growth of the Y2O3 films within an ALD window of 300 to 450 °C and a growth per cycle (GPC) up to 1.1 Å. The resulting Y2O3 films possess a smooth and crystalline structure, while avoiding any carbon and nitrogen contamination, as observed by X-ray photoelectron spectroscopy (XPS). The films showed strong resistance to fluorine-containing plasma, outperforming other resistant materials, such as silicon oxide, silicon nitride and alumina. Interestingly, the hydrophilic character exhibited by the film could be switched to hydrophobic after exposure to air, with water contact angles exceeding 90°. After annealing under N2 flow at 600 °C for 4 min, the hydrophobicity was lost, but proved recoverable after prolonged air exposure or intentional hydrocarbon exposure. The origin of these changes in hydrophobicity was examined.

Engineering CsPbBr3 quantum dots with efficient luminescence and stability by damage-free encapsulation with a-SiCx:H

Although encapsulation is an effective technique to improve the stability of perovskite quantum dots (PQDs), they are prone to photoluminescence (PL) degradation during encapsulation. Herein, a damage-free plasma-based encapsulation technique in combination with real-time in situ diagnosis is designed for CsPbBr3 QDs films. The CH4/SiH4 plasma has little destructive effects on the CsPbBr3 QDs. The a-SiCx:H films prepared with the CH4/SiH4 plasma by low-temperature plasma-enhanced chemical vapor deposition protect the CsPbBr3 QDs from surface damage during encapsulation, so that the intrinsic PL efficiency is maintained. Furthermore, the PL intensity is improved by increasing the carbon concentration in a-SiCx:H and the CsPbBr3 QDs films encapsulated by a-SiCx:H show long term stability under harsh conditions such as prolonged air exposure, UV light illumination for more than 60 days, immersion in water, as well as thermal treatment at 205 oC.