Ambient Conditions Research Articles

Metal-Bridging Cyclic Bilatriene Analogue Affords Stable π-Radicaloid Dyes with Near-Infrared II Absorption.

Stable neutral metal radicaloid complexes have been synthesized from a modified tetrapyrrolic pigment, bilatriene, with iridium(I) and rhodium(I) cyclooctadiene (COD) synthons. The bilatriene skeleton contains α-linked conjugated pyrrole units, whereas an N-confused analogue used in this work possesses β-linked pyrrole moieties at the terminal, demonstrating a unique metal binding capability. Unprecedentedly, the metal-COD cations are accommodated at the outer nitrogen sites, which induced the formation of open-shell metal-radicaloid species. The resulting compounds are highly stable under ambient conditions and demonstrated facile redox conversion to afford the corresponding cation and anion species. Furthermore, the radicaloid complexes showed a distinct second near-infrared absorption (NIR-II) capability extending up to 1500 nm along with high photostability. These features emphasized that the complexes can be potential NIR-II light-responsible photothermal and photoacoustic imaging contrast agents based on the metal-radicaloid dye platform.

Synergistic Acid-Base Action Leads to Ultrafast Decontamination of Nerve and Blister Agents by OH- Intercalated Zr4+-Doped MgAl-LDH under Ambient Conditions.

Developing materials capable of rapidly decontaminating nerve and blister agents directly under ambient conditions are crucial for practical applications. In this work, Mg3Al1- xZrx-LDH with different Zr4+ doping contents and corresponding OH- intercalated materials Mg3Al1- xZrx-LDH-OH are synthesized. First, they are used for the decontamination of nerve agents under ambient conditions, showing that increasing the Zr4+ doping amount accelerates the decontamination rate of diethyl cyanophosphonate (DECP) and soman (GD), with the half-life of DECP and GD being 3-5 times shorter with Mg3Al0.6Zr0.4-LDH (the highest Zr4+ doping content) compared to Mg3Al1-LDH. Notably, the intercalation of OH- in Mg3Al0.6Zr0.4-LDH further greatly enhances the catalytic activity for DECP and GD, the reaction half-life of DECP and GD with Mg3Al0.6Zr0.4-LDH-OH being 18s and <15s, respectively, which is the shortest recorded so far. Additionally, under ambient conditions, Mg3Al0.6Zr0.4-LDH-OH exhibits superior detoxification performance for mustard gas (HD) compared to Mg3Al0.6Zr0.4-LDH, with 92.8% of HD being removed within 6h. Mechanistic studies reveal that Mg3Al0.6Zr0.4-LDH-OH efficiently decontaminates nerve and blister agents utilizing the synergistic effect of Lewis acid-base sites (Zr4+ and laminate OH groups) and interlayer OH-. To extend the practical applications of the materials, PVA@(PAN/LDH-OH) self-detoxifying fiber loaded with Mg3Al0.6Zr0.4-LDH-OH is prepared.

Efficient and Ultralong Room Temperature Phosphorescence from Isolated Molecules under Visible Light Excitation.

Visible-light-excited ultralong organic phosphorescence (UOP) materials hold significant potential for various practical applications. Red-shifted excitation wavelength can be achieved by introducing large π-conjugation structures into organic molecules, thereby increasing intermolecular interactions and coupling. However, generating visible-light-excited UOP from isolated molecules poses a great challenge. Herein, we pioneered a strategy to achieve visible-light-excited UOP by doping organic molecules into a rigid polymer. The resulting materials exhibit an ultralong lifetime of up to 2.226 s and a high phosphorescence efficiency of 42.6% under ambient conditions. Impressively, poly(vinyl alcohol) films doped with 1 wt % different guests demonstrate blue and green visible-light-excited UOP. Moreover, they show long-persistent luminescence, lasting over 30 min at room temperature. Through control experiments and theoretical calculations, we discovered that hydrogen bonding between the guests and PVA confines the molecular motion, promoting efficient UOP. The intramolecular charge transfer within the single molecular state contributes to the low energy level, thus leading to the red-shifted absorption. This work will open a new way for developing visible-light-excited UOP based on amorphous polymers, offering highly efficient UOP and long-persistent luminescence under ambient conditions.

High-Temperature Polymorphism and Band-Gap Evolution in BaZrS3.

Barium zirconium trisulfide (BZS) is a three-dimensional (3D) perovskite with optoelectronic properties suitable for photovoltaic (PV) and light-emitting diode (LED) applications that is conventionally reported in the orthorhombic Pnma (62) symmetry. Synchrotron X-ray diffraction, thermal analysis, and Raman and absorption spectroscopy revealed three high-temperature polymorphs that appear when BZS is heated in air prior to complete oxidation (BaZrS3 + 5O2 → BaSO4 + ZrO2 + 2SO2↑) at 700 °C with the approximate stability ranges: BaZrS3 IVPnma (62)T < 400 °CBaZrS3 IIICmcm (63)400 °C ≤ T ≤ 500 °CBaZrS3 II14/mcm (140)500 °C ≤ T ≤ 700 °CDifferential scanning calorimetry (DSC) revealed exothermic features accompanying the IV → III and III → II phase changes. Furthermore, the direct band gap varied inversely with temperature with distinct energies for each polymorph (1.84 eV ≤ IV ≤ 1.65 eV; 1.65 eV ≤ III ≤ 1.54 eV; 1.54 eV ≤ II ≤ 1.52 eV). Raman spectroscopy found that polymorphic changes up to 600 °C were reversible with bands characteristic of BaZrS3 IV entirely restored upon cooling to room temperature (RT). This more complete understanding of BSZ polymorphism provides a basis for producing crystallochemical variants with enhanced optoelectronic properties under ambient conditions.

Coulombic Condensation of Liquefied Gas Electrolytes for Li Metal Batteries at Ambient Pressure

The concept of employing highly concentrated electrolytes has been widely incorporated into electrolyte design, due to their enhanced Li‐metal passivation and oxidative stability compared to their diluted counterparts. However, issues such as high viscosity and sub‐optimal wettability, compromise their suitability for commercialization. In this study, we present a highly concentrated dimethyl ether‐based electrolyte that appears as a liquid phase at ambient conditions via Li+ ‐ solvents ion‐dipole interactions (Coulombic condensation). Unlike conventional high salt concentration ether‐based electrolytes, it demonstrates enhanced transport properties and fluidity. The anion‐rich solvation structure also contributes to the formation of a LiF‐rich salt‐derived solid electrolyte interphase, facilitating stable Li metal cycling for over 1000 cycles at 0.5 mA cm‐2, 1 mAh cm‐2 condition. When combined with a sulfurized polyacrylonitrile (SPAN) electrode, the electrolyte effectively reduces the polysulfide shuttling effect and ensures stable performance across a range of charging currents, up to 6 mA cm‐2. This research underscores a promising strategy for developing an anion‐rich, high concentration ether electrolyte with decreased viscosity, which supports a Li metal anode with exceptional temperature durability and rapid charging capabilities.

Revealing Ultrafast Optical Nonlinearity of Trapped Exciton Polaritons in Atomically Thin Semiconductors.

Nonlinearities are fundamental to modern optical technologies. Exciton polaritons in semiconductor microcavities provide a promising route to strong nonlinearities. Monolayer TMDs, with tightly bound excitons and strong oscillator strength, enable polaritonic phenomena under ambient conditions but face challenges from weak polariton interactions due to small exciton Bohr radius. Although spatial confinement can boost polariton nonlinearity, the dynamics of trapped polaritons remain underexplored. Here we study the transient nonlinearities of confined polaritons in monolayer WS2 mesa cavities. We observe increasingly pronounced blueshifts within the first few picoseconds as trapping sizes decrease or excitonic fractions increase. Furthermore, our findings reveal that exciton-photon detuning, not trapping size, predominantly influences the time to reach the peak of transient nonlinearity. This insight aligns with the experimentally observed and theoretically simulated relaxation dynamics of trapped polaritons. Our findings pave the way for developing ultrafast all-optical polaritonic devices in TMD systems.

Coulombic Condensation of Liquefied Gas Electrolytes for Li Metal Batteries at Ambient Pressure.

The concept of employing highly concentrated electrolytes has been widely incorporated into electrolyte design, due to their enhanced Li-metal passivation and oxidative stability compared to their diluted counterparts. However, issues such as high viscosity and sub-optimal wettability, compromise their suitability for commercialization. In this study, we present a highly concentrated dimethyl ether-based electrolyte that appears as a liquid phase at ambient conditions via Li+ - solvents ion-dipole interactions (Coulombic condensation). Unlike conventional high salt concentration ether-based electrolytes, it demonstrates enhanced transport properties and fluidity. The anion-rich solvation structure also contributes to the formation of a LiF-rich salt-derived solid electrolyte interphase, facilitating stable Li metal cycling for over 1000 cycles at 0.5 mA cm-2, 1 mAh cm-2 condition. When combined with a sulfurized polyacrylonitrile (SPAN) electrode, the electrolyte effectively reduces the polysulfide shuttling effect and ensures stable performance across a range of charging currents, up to 6 mA cm-2. This research underscores a promising strategy for developing an anion-rich, high concentration ether electrolyte with decreased viscosity, which supports a Li metal anode with exceptional temperature durability and rapid charging capabilities.

Enhanced mechanical property of polyethylene wax/gadolinium oxide/methyl vinyl silicone rubber composites via gamma irradiation

AbstractThe properties of rubber can be changed by controlling the radiation conditions, so as to be suitable for specific application scenarios. This study compares the structure, mechanical properties, cross‐linking density, thermal properties, and shielding properties of polyethylene wax/gadolinium oxide/methyl vinyl silicone rubber (PEW/Gd2O3/MVQ) under different radiation doses and atmospheric conditions. The results showed that the tensile strength of the neutron shielding rubber exhibited growth and subsequently decreased with increasing irradiation dosage, and the tensile strength reached the optimum value of 8.29 MPa after 25 kGy in air. The hardness and cross‐linking density of the sample increase with the increase of the dose, and especially the hardness and cross‐linking density of the sample irradiated in the air atmosphere at 25 kGy were better than that in the vacuum. The addition of PEW to the rubber significantly increased the thermal neutron‐shielding rate, from 74.10% to 86.59% when 36 phr of Gd2O3 was added. The thermal neutron‐shielding rate increased from 84.42% to 88.39% when irradiated 50 kGy in air. It was found that the comprehensive performance of the rubber was optimized after irradiation of 25 kGy in the air atmosphere.Highlights The mechanical properties of rubber are enhanced by low‐dose irradiation in air. Irradiation of rubber in air is superior to irradiation in vacuum, with optimal results at 25 kGy. Rubber maintains thermal stability at low doses of irradiation. The addition of PEW improves the shielding properties. Rubber retains excellent thermal neutron‐shielding properties after irradiation.

Exploring spectropolarimetric inversions using neural fields. Solar chromospheric magnetic field under the weak-field approximation

Full-Stokes polarimetric datasets, originating from slit-spectrograph or narrow-band filtergrams, are routinely acquired nowadays. The data rate is increasing with the advent of bi-dimensional spectropolarimeters and observing techniques that allow long-time sequences of high-quality observations. There is a clear need to go beyond the traditional pixel-by-pixel strategy in spectropolarimetric inversions by exploiting the spatiotemporal coherence of the inferred physical quantities that contain valuable information about the conditions of the solar atmosphere. We explore the potential of neural networks as a continuous representation of the physical quantities over time and space (also known as neural fields), for spectropolarimetric inversions. We have implemented and tested a neural field to perform one of the simplest forms of spectropolarimetric inversions, the inference of the magnetic field vector under the weak-field approximation (WFA). By using a neural field to describe the magnetic field vector, we regularized the solution in the spatial and temporal domain by assuming that the physical quantities are continuous functions of the coordinates. This technique can be trivially generalized to account for more complex inversion methods. We have tested the performance of the neural field to describe the magnetic field of a realistic 3D magnetohydrodynamic (MHD) simulation. We have also tested the neural field as a magnetic field inference tool (approach also known as physics-informed neural networks) using the WFA as our radiative transfer model. We investigated the results in synthetic and real observations of the Ca ii line. We also explored the impact of other explicit regularizations, such as using the information of an extrapolated magnetic field, or the orientation of the chromospheric fibrils. Compared to traditional pixel-by-pixel inversions, the neural field approach improves the fidelity of the reconstruction of the magnetic field vector, especially the transverse component. This implicit regularization is a way of increasing the effective signal to noise of the observations. Although it is slower than the pixel-wise WFA estimation, this approach shows a promising potential for depth-stratified inversions, by reducing the number of free parameters and inducing spatiotemporal constraints in the solution.

Residual flexural performance of large-scale ferronickel slag alkali-activated concrete slabs after fire exposure

Background This study explores the flexural behavior of unfired and fired one-way slabs constructed from reinforced ferronickel slag-based alkali-activated concrete (AAC). Despite growing interest in AAC as a sustainable alternative to ordinary Portland cement (OPC), limited research exists on large-scale structural elements, particularly under post-fire conditions. Methods Four slabs (2.1 × 0.9 × 0.18 m3) were tested: two made of AAC and two of OPC concrete with comparable compressive strengths. In each group, one slab served as a reference and was tested under monotonic four-point bending in its original state. The other was exposed to a standard fire curve on the tensioned side, then cooled to ambient conditions before mechanical testing. Additional analyses, including mercury intrusion porosity (MIP) and scanning electron microscopy (SEM), were conducted to evaluate fire-induced microstructural changes in the AAC slabs. Results The AAC slabs demonstrated a load capacity 6% lower than OPC slabs. However, AAC slabs exhibited better post-fire retention of stiffness and ductility. Microstructural analysis revealed increased porosity and microcracking in AAC after fire exposure, which influenced its mechanical performance. Conclusions The results suggest that ferronickel slag-based AAC can provide comparable performance to OPC concrete in flexural applications, with enhanced retention of stiffness and ductility after fire exposure. These findings support the viability of AAC for structural applications while highlighting its resilience under post-fire conditions.

Heat wave: a new characterization in terms of energy

Heat waves (HW) are prolonged periods of excessively hot weather that can cause severe socioeconomic and environmental impacts. This study aims to evaluate the differences in stored heat and turbulent flux partitioning during a heat wave event in Mexico City, using observations from an eddy covariance tower during the period from 14 June to 21 June 2023. During this period, net radiation (Rn) and sensible heat flux (H) increased significantly, particularly from noon to evening, reflecting stable atmospheric conditions. The air temperature showed a noticeable increase in the afternoon and evening, whereas absolute humidity decreased. We found that during the heat wave, the Bowen ratio (β) increased by 80% during daylight hours and 65% over a full 24-hour period compared to the pre-heat wave period. This heat release at night prolonged warm conditions, intensifying heat stress. The partitioning of net radiation for latent heat (LE), sensible heat (H), and heat storage (ΔQs) showed significant changes; during the heat wave, 51% of Rn was allocated to H and 34% to ΔQs, compared to pre-heat wave values of 49% and 27%, respectively. This study introduces a new characterization of heat waves in terms of energy, emphasizing the significant shifts in energy flux partitioning and storage. The new characterization highlights the critical role of urban heat storage and its release in exacerbating heat stress during and after heat wave events. This approach provides a comprehensive understanding of the energy dynamics during heat waves, which is essential for developing effective mitigation strategies to combat the adverse effects of extreme heat in urban environments.

Visual and microscopic tests of composite PV module samples for the construction of roof and facade type BIPV

The introduction of new material solutions into the BIPV (Building Integrated Photovoltaics) requires the need to check their suitability in this area. This especially applies to resistance to weather conditions and resistance to UV radiation. The authors conducted a series of tests on samples of photovoltaic modules made using a composite lamination technology based on glass fibres and hardened resins. The resistance of such a structure to atmospheric conditions and degradation by UV rays was investigated. Both of these areas have a significant impact on the efficiency of such a solution in terms of converting solar energy into electricity and the service life of the solution. It was found that delamination of the composite PV modules can be avoided in the case of some studied resins (e.g. LG 385).

Simulation of the Steady Mixing State of Black Carbon With a Two‐Dimensional Sectional Model

AbstractBlack carbon (BC) strongly absorbs solar radiation and has a warming effect on the earth‐atmosphere system. BC experiences continuous aging, making its optical properties a great uncertainty due to the complex mixing state. To address this issue, we developed a sectional model which is capable of tracking both the aerosol size and the BC core size. This model was applied to simulate BC aging process. The atmospheric observational data from a slightly polluted case was employed to drive the model. It is shown that BC's characteristics tend to reach a steady state within 12 hr. Our analysis reveals that, in the steady state, the size distribution of BC‐containing particles demonstrates a notable characteristic: the particle size distribution decreases exponentially as the particle size increases. This exponential relationship provides a simplified yet accurate representation of the complex BC mixing state. This steady‐state size distribution of BC‐containing particles is validated across diverse atmospheric conditions.

Sustainable Synthesis of Palladium‐Immobilized Covalent Organic Frameworks: A One‐step Sonochemical Strategy

AbstractThe rapid and environmentally benign synthesis of metal‐immobilized covalent organic frameworks (metal/COFs) for heterogeneous catalysis is a pervasive challenge, as the mainstream synthesis is exceedingly time‐consuming (up to four days) and demands the use of hazardous solvents. Herein, we describe a sustainable and efficient one‐step sonochemical strategy for constructing diverse palladium (II)‐immobilized COFs (Pd(II)/COFs). By merging the sonochemistry‐assisted COF synthesis and in situ Pd (II) immobilization into a single step, this strategy enables the rapid formation of Pd(II)/COF hybrids within an hour under ambient conditions using water as the solvent. Notably, gram‐scale synthesis of Pd(II)/COFs is achievable. The resulting Pd(II)/COFs exhibit superb crystallinity and high surface area, leading to remarkable activity, excellent functionality tolerance, and high recyclability for the Suzuki–Miyaura cross‐coupling reaction of aryl bromides and arylboronic acids at room temperature. This one‐step sonochemical strategy effectively addresses the long‐lasting limitations of traditional multistep synthesis, paving a fast and sustainable avenue to diversified metal/COF hybrids for heterogeneous catalysis and potentially other applications.

Siloxane as Humidity‐Resistant and Stabilizing Additive for Ambient‐Processed Organic Solar Cells

AbstractHigh‐performing organic solar cells (OSCs) being processed in ambient conditions and possessing long‐term stability are desired toward commercialization. Here, resultantly bifunctional additive is proposed for organic active layer, which can greatly enhance humidity endurance during the air‐processing of the active layer and device stability in the meantime. Intriguingly, with 1% octamethyltrisiloxane (3Si) as the additive, casting PM6:L8‐BO active layer even in 90% relative humidity (RH) air could show comparable efficiency to that in N2 condition. Furthermore, the 3Si‐processed active layers also display remarkably enhanced thermal and light stabilities in conventional OSCs. After thermal aging at 85 °C for 1000 h and simulated solar light aging with UV band at 100 mW cm−2 and 55°C for 1000 h, the 3Si‐processed PM6:L8‐BO binary OSCs maintain 91.6% and 86.1% of the initial efficiency, leading to final averaged efficiencies of 16.17% and 15.42%, respectively. The results represent the most stable OSCs based on additive strategy. The universality of siloxane as a humidity‐resistant and stabilizing agent is also confirmed with other active layer systems, paving a way for broader application of the bifunctional additive.

Monitoring Air Quality in Bhopal: A Comparative Study of Pollutant Levels at Hamidia Road Chowk and T.T. Nagar in 2022

Urban air pollution is a growing environmental and health challenge in developing countries, driven by industrialization, enlargement of vehicular traffic, and population density. This study focuses on two distinct monitoring sites in Bhopal, India: Hamidia Road Chowk, characterized by high traffic density, and T.T. Nagar, a densely populated residential area. Monthly data for 2022 on key pollutants, including particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), nitrogen oxides (NO2), carbon monoxide (CO), ozone (O3), and heavy metals, were analysed to define seasonal variations and conformity with the National Ambient Air Quality Standards (NAAQS). Findings indicate higher pollutant concentrations in the winter and early summer, correlating with atmospheric conditions and enlargement emissions during these periods. Notably, pollutant levels frequently exceeded NAAQS limits, posing significant health risks to urban populations. The results underscore the significance of continuous air property monitoring and the implementation of targeted emission control measures, especially in high-traffic and densely populated areas. This study contributes to the perception of air pollution dynamics in rapidly urbanizing cities and provides a foundation for informed policy-making to improve urban air quality.

Fused filament fabrication of polyetheretherketone in vacuum: the influence of high vacuum on layer adhesion in z-orientation

AbstractThe application of fused filament fabrication (FFF) in vacuum changes the heat transfer of the process. This work investigates the influence of the working ambient pressure conditions in FFF-based 3D printing of polyetheretherketone (PEEK) specimens, and its impact on the resulting part strength. Layer adhesion drastically improves with decreasing pressure, maximum layer adhesion is reached for ambient pressure below $$10^{-3}$$ 10 - 3 mbar. We show that simple and low-cost vacuum equipment is sufficient to achieve such pressure conditions, making this process interesting for the general processing of high-temperature polymers using FFF.

Particle Swarm Optimization for k-Coverage and 1-Connectivity in Wireless Sensor Networks

Wireless Sensor Networks are used in an ever-increasing range of applications, thanks to their ability to monitor and transmit data related to ambient conditions in almost any area of interest. The optimization of coverage and the assurance of connectivity are fundamental for the efficiency and consistency of Wireless Sensor Networks. Optimal coverage guarantees that all points in the field of interest are monitored, while the assurance of the connectivity of the network nodes assures that the gathered data are reliably transferred among the nodes and the base station. In this research article, a novel algorithm based on Particle Swarm Optimization is proposed to ensure coverage and connectivity in Wireless Sensor Networks. The objective function is derived from energy function minimization methodologies commonly applied in bounded space circle packing problems. The performance of the novel algorithm is not only evaluated through both simulation and statistical tests that demonstrate the efficacy of the proposed methodology but also compared against that of relative algorithms. Finally, concluding remarks are drawn on the potential extensibility and actual use of the algorithm in real-world scenarios.

Rectifiable Conductive Thermal Diodes Enabling Thermal Circuits with Selectable Operations for Thermal Logic Applications

AbstractThermal logic paves the way to replace electric logic in scenarios where electronic signals are susceptible to interference or traditional electronics cannot be used, however, is still considered a theoretical and numerical stage. Emerging thermal metalmaterials (TMMs) have the potential to enhance thermal information processes. Compared to TMMs with single‐and‐fixed heat transfer capabilities, rectifiable‐TMMs enable thermal circuits to perform selectable operations, but they are also limited by low operating temperatures and narrow temperature biases. Here, macro‐ and experimental thermal diodes with tree‐like eutectic gallium‐indium/printed polylactic‐acid (EGaIn/PPLA) interface, are demonstrated to be capable of extending asymmetric heat transfer difference to 5.81 times in ambient operation, compared with basic EGaIn/PPLA interface with an input temperature bias of 63.7 °C. Given this, basic thermal gates can be constructed through the incorporation of resistors and a pair of diodes working in the same or opposite directions, with the propagation delay time td within 18 min. Compound logic gates can be cascaded by basic gates in the same way as composed Boolean functions, with td within 4 min. Such thermal circuits prove to perform reliably under dynamic ambient conditions, advancing the engineering of devices designed to manipulate thermal energy and process abundant thermal information.

Electrophilic Intermediates in the Nef and Meyer Reactions: A Computational Study.

The generation, interconversion, and reactivity of electrophilic species generated upon activation of nitroalkanes with protic acids (the Nef and Meyer reactions) were investigated by quantum-chemical calculations. N,N-Bis(hydroxy)iminium (R2C═N+(OH)2) and N-oxoiminium (R2C═N+═O) cations were shown to be produced independently from aci-nitroalkanes, while N-hydroxynitrilium cations (RC≡N+-OH) were formed via nearly barrierless C-H bond cleavage in N-oxoiminium cations. The N-oxoiminium and N-hydroxynitrilium cations whose formation is favored under highly acidic anhydrous conditions are strong electrophiles capable of reacting even with nonactivated arenes under ambient conditions. The N-oxoiminium cations R2C═N+═O are highly unusual ambident species containing three contiguous electrophilic centers (C, N, and O atoms). Nucleophilic addition at the oxygen atom is less preferred than the C- and N-attack yet possible in an intramolecular variant. These computational results shed light on some key aspects of the mechanisms of the Nef and Meyer reactions and predict the possibility of numerous interrupted versions of these reactions.