Ambient Conditions Research Articles

Revisiting the Role of Atmospheric Initial Signals in Predicting ENSO

Abstract El Niño–Southern Oscillation (ENSO) provides an important source of global seasonal–interannual predictability, while its prediction encounters bottlenecks. Besides the slow-varying air–sea feedbacks, high-frequency atmospheric signals (HFASs) act on ENSO evolution. This study revisits the role of atmospheric initial signals in ENSO prediction using an atmosphere–ocean coupled model. Two sets of sensitivity hindcasts are conducted. One utilizes a pure sea surface temperature (SST) nudging for initialization so that no observed atmospheric internal signal is assimilated. The other applies a combination of the SST nudging and spectral nudging of JRA-55 reanalysis, which not only assimilates the observed atmospheric states and hence realizes skillful predictions of HFAS at the initial stage but also improves the oceanic initial conditions (ICs), especially around the thermocline. Unexpectedly, the better atmosphere–ocean ICs neither improve ENSO prediction nor overcome the spring prediction barrier. Further analysis of Bjerknes stability index suggests that underestimated negative feedbacks and insufficient responses of ocean currents and thermocline slope to atmospheric internal winds may account for the failure. Nevertheless, assimilating the atmospheric information partly improves the prediction of El Niño onset, especially for two recent extreme cases (i.e., 1997/98 and 2015/16). This improvement is associated with better representations of initial westerly wind bursts (WWBs) that excite subsequent downwelling equatorial Kelvin waves. However, due to unpredictable WWBs and underestimated wind response to the SST warming owing to the cold tongue biases in boreal summer, the zonal advective feedbacks are underestimated and thus further development of El Niño cannot be well predicted. This study suggests the importance of initial atmospheric signals despite the limitation, prompting further efforts to improve model physics.

Electrocatalytic Urea Synthesis via C‐N Coupling over Fe‐Based Catalyst

Electrochemical urea synthesis under ambient conditions offers a promising alternative to traditional methods, yet suffers from inefficient production due to poor binding of reactants to the catalyst surface, leading to competitive pathways. Here, we report an electrochemical route for urea synthesis by dual reduction of CO2 and N2 gases using FePc catalyst. The FePc electrocatalyst showed a urea yield rate of 357 µmol h−1 gcat−1 with a Faradaic efficiency (FE) of 14.36% at −0.4 V vs RHE. This insight offers an awareness into the development of an electrochemical route for the efficient electrosynthesis of urea via C–N coupling.

Synthesis, Structures and Air‐stable N‐type Organic Field‐effect Transistor (OFET) Properties of Functionalized‐phenanthrene Conjugated Asymmetric N‐heteroacenes

The development of stable high‐performance n‐type organic semiconductors for applications in organic field‐effect transistors (OFETs) under ambient conditions is desirable but challenging. To address this issue, we here synthesized a series of functionalized‐phenanthrene conjugated asymmetric N‐heteroacenes, where the phenanthrene moiety was modified by N substitution or Br functionalization at different positions to induce various degrees of asymmetry in their structures. The photophysical and electrochemical properties of these molecules were studied, and their packing patterns were analysed. The OFETs based on these materials were fabricated through simple spin‐coating method, and the as‐resulted thin films were treated with different conditions. The devices exhibit typical n‐type performances under ambient conditions with charge carrier mobilities up to 4.27 × 10‐3 cm2 V‐1 s‐1. The crystallinities and morphologies of these thin films were studied to investigate the correlations between the device performances and thin‐film characteristics. Our study suggests that phenanthrene conjugated N‐heteroacenes can be developed as promising air‐stable solution‐processable n‐type semiconducting materials, and Br modification at certain positions of phenanthrene is beneficial in adjusting the thin‐film properties for the improvement of OFET performances.

Hydroxyl Radical Mediated Heterogeneous Photocatalytic Baeyer–Villiger Oxidation over Covalent Triazine/Heptazine‐Based Frameworks

AbstractThe Baeyer–Villiger (B–V) oxidation of ketones to the corresponding lactones/esters is a classic and essential reaction in the chemical industry. However, this oxidation process has not yet been achieved in ambient conditions with the aid of oxygen and heterogeneous photocatalysts. In this study, we developed an organic photocatalytic system using covalent triazine/heptazine‐based frameworks (CTF‐TB/CHF‐TB) to enable the B–V oxidation reaction under mild conditions through a cascade reaction pathway. Experimental data and theoretical calculations showed that heptazine/triazine units can “chelate” and decompose the in situ generated H2O2 into hydroxyl radicals (⋅OH). Compared to conventional methods that primarily involve metal‐activated benzaldehyde at elevated temperatures (e.g., 60 °C), the ⋅OH generated in our study can readily cleave the C−H bond of benzaldehyde, forming an active intermediate that drives subsequent sequential processes: O2→H2O2→⋅OH→Ph‐CO⋅→Ph‐COOO⋅. By employing this photocatalytic process, a yield of 91 % and a selectivity of over 99 % were obtained in the oxidation of cyclohexanone to caprolactone at room temperature. This performance is comparable to the state‐of‐the‐art catalysts, and our CHF‐TB catalyst demonstrates impressive reusability, maintaining a high yield after 5 consecutive runs. This work presents a straightforward approach for C−H cleavage by organocatalysts to produce ϵ‐caprolactone in a mild manner by B–V oxidation.

Wear-free sliding electrical contacts with ultralow electrical resistivity

Sliding electrical contacts are commonly applied in electrical connectors, such as conductive slip rings, pantographs, switches, and commutators. However, they suffer from several unavoidable problems caused by friction and wear, including high energy consumption, intermittent failures, limited life, and even failure disasters. In this study, we realized an ultralow-friction and long-distance wear-free state, defined as structural superlubricity (SSL), between sliding electrical interfaces under ambient conditions. A conductive SSL can be implemented in experiments with single-crystal graphite flakes on flattened metals, such as Au and Ni films. Furthermore, we found that depositing a 2 to 3-nm-thick diamond-like carbon (DLC) film on a nickel alloy can lead to an even lower resistivity than that of metals alone. In addition, we revealed the mechanism by which DLC films can improve the conductivity between graphite and metals through density functional-theory simulations. In addition, we prepared a prototype of the SSL slip ring and proved that it possessed ultralow friction, was wear-free, and had no intermittent failures. Consequently, our results demonstrate a unique type of electrical-contact interface for applications requiring conduction while sliding. Thus, we opened the door for SSL electromechanical coupling.

Rapid Degradation of Dye Effluents with A SnS Catalyst: A Sustainable Approach Using Natural Light Under Ambient Conditions.

Dye degradation presents a persistent challenge in addressing water pollution. While several methods, including adsorption, biodegradation, and advanced oxidation processes, have been extensively explored, photocatalysis remains one of the most effective techniques. Conventional photocatalytic dye degradation processes often rely on expensive light sources and are time-intensive. Herein, we synthesized a SnS catalyst by the solvated metal atom dispersion (SMAD) method, using Sn foil and sulfur powder. The catalyst exhibited remarkable performance, achieving complete degradation of methylene blue within 2 minutes under ambient room light, without the need for any external light source. Similar degradation efficiency was achieved for methyl orange. To evaluate the role of light for the degradation, control experiments were conducted in the dark using methylene blue as a model dye. Although the degradation rate was slightly reduced, the catalyst still facilitated dye degradation in the absence of light. Additionally, the catalytic performance was tested with four other dyes under natural light, all of which yielded promising results, demonstrating the versatility and effectiveness of the SnS catalyst in dye degradation. This work highlights the potential of the SnS catalyst for efficient and rapid dye degradation under both light and dark conditions, offering an energy-efficient solution for wastewater treatment.

Zn-Modified TiO2 Thin-Films for Real-Time Formaldehyde Sensing at Room Temperature

Abstract This study explores the fabrication and application of zinc-modified titanium dioxide (Zn-TiO2) thin-films for real-time recognition of volatile organic compounds (VOCs), with a particular emphasis on formaldehyde (HCHO) sensing at room temperature. The Zn-TiO2 thin-films were produced using an economical spray-pyrolysis method. Structural, morphological, and optical characterizations confirmed the successful integration of zinc with varied Wt.% (0, 2, 4, and 6) into the TiO2 lattice. The real-time monitoring capabilities of the sensors were assessed against a range of VOCs, highlighting its specificity for formaldehyde detection amidst diverse environmental constituents. The fabricated thin film sensors with zinc dopant were optimized to enhance the sensor's performance. 4 Wt.% Zn-TiO2 demonstrated excellent sensitivity to formaldehyde vapor at ambient conditions, showcasing a rapid and selective response. The underlying sensing mechanism was explored, emphasizing the role of zinc doping in tailoring the material's surface properties and facilitating enhanced adsorption of formaldehyde molecules. The study underscores the potential of Zn-modified TiO2 thin films as a reliable and efficient platform for real-time VOC monitoring, with a specific focus on HCHO sensing at room-temperature. The sensor shows remarkable stability and repeatability, making it a promising candidate for continuous monitoring applications.

“Novel Metal‐Free Porphyrin with Ionic Liquid and Sulphonic Acid Moieties for Visible Light Assisted Photocatalytic C−N Coupling of Heterocyclic Compounds with Aryl Halides”

AbstractMetal‐free Buchwald‐Hartwig type photocatalytic approach for N‐substitution of 1,2,4‐triazole at normal temperature was explored for the first‐time using novel imidazolium based Brønsted acid functionalized porphyrin (ImBAFPc). The energy band gap and Hammett acidity were determined by UV‐Vis spectrophotometer. The energy band gap, 1.06 eV supported absorption of radiation in the visible region. The N‐arylation of 1,2,4‐triazole with various Ar−X was achieved in a home‐made photoreactor by heterogeneous, recyclable ImBAFPc photocatalyst under irradiation of 5 W LED with good yields. The protocol tolerated electron donating and attracting Ar−X, including inactivated chlorobenzene, affording the arylated triazole with admirable yields. under ambient photocatalytic conditions.

Using a New Pt(II) Source to Make Pt(II) Lantern‐Shaped Cages, Including Low‐Symmetry, Heteroleptic, and Multicavity Examples

Current synthetic methods towards Pt(II) lantern‐shaped cages involve the use of dry solvent, inert atmosphere, lengthy reaction times, and highly variable yields if isolated. Starting materials such as [Pt(CH3CN)4](BF4)2 suffer from a poor shelf‐life, reducing the synthetic accessibility of various Pt(II) architectures. A new Pt(II) source (with varied counterions), [Pt(3‐ClPy)4](X)2 (3‐ClPy = 3‐chloropyridine, X = BF4‐, OTf‐, NO3‐), is developed and characterised, showing greatly enhanced shelf‐life characteristics under ambient atmospheric conditions. Using this starting material, the assembly of Pt(II) lantern‐shaped cages was completed in as little as 1.5 hours with wet solvent and ambient atmosphere. The first examples of low‐symmetry, heteroleptic and multicavity Pt(II) lantern‐shaped cages are reported using this approach. Attempts towards an M6L8 octahedron using a tritopic ligand instead generate an interesting M2L4 cage with unbound pyridyl arms. Ligands and cages are characterised by NMR spectroscopy, IR spectroscopy, mass spectrometry, and X‐ray crystallography in some cases.

Optimized Scintillation Imaging in low dose rate and bright room light conditions

Abstract Objective. To develop a robust method for non-contact surface dosimetry during Total Body Irradiation (TBI) that uses an optimally paired choice of scintillator material with camera photocathode and can work insensitively to the normal ambient room lighting conditions (~500 Lux). 
Approach: This goal was approached by assessing the emission contrast of scintillator signal to background room ratio (SBR) detected by the camera, in the challening conditions of low dose rate TBI with high room lights. A total of 9 fast-response scintillators, 3 wavelength shifters, and 2 camera photocathodes were systematically tested to determine the optimal combination. The effects of room lights on the scintillator signal and the background signal were assessed to avoid signal saturation while retaining accurate dose measurement. A bandpass wavelength filter was then applied to reduce the effects on room lights and scintillator signal.
Main Results: One scintillator (EJ262) combined with a blue-green sensitive photocathode camera and a 500nm band pass filter produced the greatest available scintillator SBR of 95 with maximal room lights on. The caveat is that this design rejects all patient Cherenkov light, which can be useful for visualizing the patient treatment. Another option which retained the Cherenkov signal but produced less available scintillator signal was found with another scintillator (EJ-260) and a red photocathode camera with SBR of 35, but a narrow bandpass filter is required to make it work in ambient room lights, which addition will also remove most of the Cherenkov signal. 
Significance: Non-contact scintillator imaging can be used for surface dosimetry in TBI with appropriate pairing of scintillator emission spectrum and camera photocathode sensitivity or optical filtering range.

Using a New Pt(II) Source to Make Pt(II) Lantern‐Shaped Cages, Including Low‐Symmetry, Heteroleptic, and Multicavity Examples

Current synthetic methods towards Pt(II) lantern‐shaped cages involve the use of dry solvent, inert atmosphere, lengthy reaction times, and highly variable yields if isolated. Starting materials such as [Pt(CH3CN)4](BF4)2 suffer from a poor shelf‐life, reducing the synthetic accessibility of various Pt(II) architectures. A new Pt(II) source (with varied counterions), [Pt(3‐ClPy)4](X)2 (3‐ClPy = 3‐chloropyridine, X = BF4‐, OTf‐, NO3‐), is developed and characterised, showing greatly enhanced shelf‐life characteristics under ambient atmospheric conditions. Using this starting material, the assembly of Pt(II) lantern‐shaped cages was completed in as little as 1.5 hours with wet solvent and ambient atmosphere. The first examples of low‐symmetry, heteroleptic and multicavity Pt(II) lantern‐shaped cages are reported using this approach. Attempts towards an M6L8 octahedron using a tritopic ligand instead generate an interesting M2L4 cage with unbound pyridyl arms. Ligands and cages are characterised by NMR spectroscopy, IR spectroscopy, mass spectrometry, and X‐ray crystallography in some cases.

Characterization of the Elemental Composition of Aerosols Emitted in the Dry Season of the Pantanal Wetland, Brazil

The Brazilian Pantanal region experiences intense biomass burning during the dry season, releasing large quantities of gasses and particles into the atmosphere, which have serious implications on both the climate system and public health. Understanding the dynamics of these emissions is crucial for mitigating the impact on the ecosystem, its functioning, and potential anthropogenic disturbances. This study focused on analyzing emissions in the northern Pantanal during the 2022 drought. Concentrations of fine particulate matter (PM2.5), black carbon (BC), and 25 chemical elements were measured using gravimetry, reflectance analysis, and X-Ray fluorescence, respectively, from samples collected between August and October 2022. The average concentrations of PM2.5 and BC increased approximately 4-fold and 2.5-fold, respectively, compared to averages from a decade ago. Significant increases were also observed in elements such as sulfur (S), potassium (K), iron (Fe), and silicon (Si). The maximum concentrations were comparable to values typical of the southern Amazon, a region known for high deforestation rates and land use changes. Elemental analysis revealed substantial shifts in concentrations, primarily associated with biomass burning (BB) and soil suspension. Additionally, enrichment factor (Ef) analysis showed that lead (Pb) levels, correlated with human activities, were 200 times higher than those found under clean atmospheric conditions.

Climate change and plant pathogens: Understanding dynamics, risks and mitigation strategies

AbstractClimate change is reshaping the interactions between plants and pathogens, exerting profound effects on global agricultural systems. Elevated tropospheric ozone levels due to climate change hinder plant photosynthesis and increase vulnerability to biotic invasion. The prevailing atmospheric conditions, including temperature and humidity, profoundly influence fungal pathogenesis, as each stage of a pathogen's life cycle is intricately linked to temperature variations. Likewise, climate change alters bacterial behaviour, fostering increased production of extracellular polysaccharides by plant‐pathogenic bacteria in warmer temperatures. Heat‐adapted bacteria, such as Burkholderia glumea and Ralstonia solanacearum, are emerging as significant global threats as temperature rise. Viruses, too, respond dynamically to climate shifts, with certain species favouring warmer climates for replication, resulting in expanded geographical ranges and modified transmission patterns. Nematodes, formidable constraints in crop production, exhibit temperature‐dependent life cycles and would have potentially accelerated proliferation and distribution as global warming progresses. Molecular‐level changes in pathogenesis, induced by temperature fluctuations, influence various pathogens, thereby impacting their virulence and interactions with host plants. Modelling studies predict changes in disease risks and distributions under future climate scenarios, highlighting the necessity of integrating climate data into crop disease models for accurate forecasts. Mechanistic and observational models illustrate pathogen behaviours amidst changing environmental conditions, providing crucial insights into future disease dynamics. In addition, controlled experiments study disease responses under simulated climate scenarios, underscoring the urgency for comprehensive research to devise effective resistance strategies against severe plant diseases.

Balloon Baseline Stratospheric Aerosol Profiles (B2SAP)—Perturbations in the Southern Hemisphere, 2019–2022

AbstractVolcanic and pyrocumulonimbus (pyroCB) injections into the stratosphere perturb the aerosol layer and can have important radiative and chemical impacts on timescales spanning from months to several years. Repeated in situ balloon‐borne measurements of aerosol size and number concentration (>140 nm in diameter), ozone, water vapor, and atmospheric state variables made at midlatitudes in the southern hemisphere (SH) since 2019 enable us to better characterize such events. We use this record and coincident lidar extinction profiles to study several moderate to large stratospheric perturbations in the SH between 2019 and 2022 in detail, including the Australian New Year Super Outbreak (ANYSO) pyroCB in 2020. Median vertical profiles of aerosol number concentration, effective radius, and surface area in SH midlatitudes are also compared with those recorded in Northern Hemisphere midlatitudes under baseline conditions using an identical payload. These data depict the variability in stratospheric aerosol properties in the SH midlatitudes during this period and provide a benchmark for global sectional aerosol models. They reveal that sulfate particle size distributions under baseline conditions and in volcanic plumes are relatively well represented in the Community Earth System Model—Community Aerosol Radiation Model for Atmospheres (CESM‐CARMA), but more observations of biomass burning plumes are needed to improve model skill in simulating pyroCB. Comparisons between in situ and lidar observations also highlight a need for more observations of aerosol composition and refractive index in both fresh and aging biomass burning plumes.

Biological treatment of eutrophicated lagoon water with Tetradesmus dimorphus under ambient conditions: a sustainable alternative for lipid production

Biological treatment of eutrophicated lagoon water with Tetradesmus dimorphus under ambient conditions: a sustainable alternative for lipid production

High-Conversion Propane Dehydrogenation by Photocatalysis under Ambient Conditions

High-Conversion Propane Dehydrogenation by Photocatalysis under Ambient Conditions

Postharvest treatment of navel oranges with fluroxypyr, 2-methyl-4-chlorophenoxyacetic acids, and 2,4-dichlorophenoxyacetic maintains physiological quality during ambient storage

Two batches of Green mature Navel oranges with calyxes attached were obtained from a farmer from Juaben Municipality in the Ashanti region of Ghana and were dipped for 2 minutes with fluroxypyr, and 2-methyl-4-chlorophenoxyacetic acid (MCPA), were assessed against the commercial 2,4-D at 0.1 and 0.2 mmol L-1 stored under ambient conditions (24±2 °C and 55-60% RH) for 4 weeks. The results showed that pre-storage dipping with fluroxypyr was the most effective in suppressing endogenous ethylene production and respiration rate, reduced calyx changes, and fruit rot, and retained fruit sensory attributes compared with MCPA 2,4-D, or untreated fruit at the end of storage life of four weeks. The effect of 2,4-D and MCPA on fruit rot, calyx browning, abscission, and fruit internal quality, was similar; which was not significantly different during storage. Dipping fruit with 0.1 mmol L-1 fluroxypyr was more effective in maintaining the quality of oranges and could be a substitute for current commercial 2,4-D.

Heat Exchanger Improvement of a Counter-Flow Dew Point Evaporative Cooler Through COMSOL Simulations

Due to modern comfort demands and global warming, heating, ventilation, and air conditioning (HVAC) systems are widely used in many homes and buildings. However, HVAC based on the Vapor Compression System (VCS) is a major energy consumer, accounting for 20–50% of a building’s energy consumption and responsible for 29% of the world’s CO2 emissions. Dew-point evaporative coolers offer a sustainable alternative yet face challenges, e.g., dew point and wet bulb effectiveness. Given the above, dew point evaporative cooling systems may find a place to dethrone conventional air conditioning systems. This research aims to design a dew point evaporative cooler system with better performance in terms of dew point and wet bulb effectiveness. In terms of methodology, a heat exchanger as part of a counter-flow dew point cooling system was designed and analyzed using COMSOL simulations under different representative climatic, geometric, and dimensional conditions, taking into account turbulent flow. Next, our model was compared with other cooling systems. The results show that our model performs similarly to other cooling systems, with an error of around 6.89% in the output temperature at low relative humidity (0–21%). In comparison, our system is more sensitive to humidity in the climate, whereas heat pumps can operate in high humidity. The average dew point and wet bulb effectiveness were also higher than reported in the literature, at 91.38% and 147.84%, respectively. In addition, there are some potential limitations of the simulations in terms of the assumptions made about atmospheric conditions. For this reason, the results cannot be generalized but must be considered as a starting point for future research and technology development projects.

Numerical investigation of thermal-flow processes in the ejector-condenser for selected geometrical parameters

The paper presents the results of analysis of thermal-flow processes in the ejector-condenser for selected geometrical param-eters using CFD (Computational Fluid Dynamics) methods. The ejector-condenser is the water-driven, two-phase ejector responsible for creating a sub-pressure allowing exhaust gases (steam and CO2 mixture) to be entrained, condensing steam, and then increasing the pressure above the atmospheric conditions. The axisymmetric numerical model was developed to take into account multiphase, turbulent flow with steam condensation in the presence of inert gas. The influence of the selected geometrical parameters, such as the motive nozzle's and mixing chamber's diameters on the ejector performance was investi-gated. CFD analysis results are presented in the form of developed scalar distributions as well as pressure, temperature and steam mass flow changes along the flow path. Performances for different geometry modes were calculated and compared using parameters such as compression ratio, expansion ratio, mass entertainment ratio and condensation efficiency. The max-imum achieved compression ratio for the analyzed geometrical variants is 1.113 for the assumed mass entertainment ratio of 0.0295. The condensation efficiency varies in a range of 49.6%–91.4% depending on motive fluid inlet conditions and geom-etry mode.

Coral recruits demonstrate thermal resilience

Marine heatwaves are becoming more frequent during summer and pose a significant threat to coral reef ecosystems. Restoration efforts have the potential to support native coral populations and guard them against some degree of environmental change, while global action against climate change takes place. Interspecific hybridization is one approach through which resilient coral stock could be generated for restoration. Here we compared the performance of Acropora kenti and A. loripes hybrid and purebred coral recruits under a simulated thermal stress event. A. kenti eggs were successfully fertilized by A. loripes sperm to produce ‘KL’ hybrids, but no ‘LK’ hybrids could be produced from A. loripes eggs and A. kenti sperm. Despite corals in the elevated treatment accruing thermal stress (>12 degree heating weeks over 2 months) known to result in mass bleaching, both purebred and hybrid recruits showed no signs of stress under the simulated temperature regime, based on the performance indicators survivorship, size, color (a proxy of bleaching), and photochemical efficiency of photosystem II. Comparisons between the hybrids and purebreds studied here must be interpreted with caution because hybrid sample sizes were small. The hybrids did not outperform both of their purebred counterparts for any metrics studied here, demonstrating that there are limitations to the extent to which interspecific hybridization may boost the performance of coral stock. In general, the purebred A. loripes recruits performed best under both ambient and elevated conditions. The performance of the KL hybrid corals was similar to the maternal parental species, A. kenti, or not significantly different to either parental purebred species. The Symbiodiniaceae communities of the KL hybrids were characteristic of their maternal counterparts and may have underpinned the performance differences between the A. kenti/KL hybrid and A. loripes recruits.