Air Conditions Research Articles

An Ambipolar Alkynylborane Compound with Nearly Trap-Free Charge-Carrier Transport under Ambient Air Conditions

An Ambipolar Alkynylborane Compound with Nearly Trap-Free Charge-Carrier Transport under Ambient Air Conditions

Ambient Air Deposition Allows Reaching Record Light Use Efficiency in FAPbI3 Perovskite Solar Cells.

Semi-transparent solar cells represent an exciting opportunity for sustainable energy production, thanks to the possibility of being integrated into buildings and urban environments, effectively exploiting the already existing space. Perovskite solar cells (PCSs) are ideal candidates, offering high power conversion efficiencies (PCEs) combined with a tuneable band gap and adjustable thickness, which allow a convenient modulation of the average visible transmittance (AVT). However, balancing high PCE and high AVT is a challenging target. This study uncovers that depositing the perovskite layer based on Formamidinium Lead Iodide (FAPbI3) thin films in ambient air, rather than in a nitrogen-controlled atmosphere, allows an increase in the AVT value of up to >40% while also enhancing the photovoltaic performance and stability. The optoelectronic quality of the as-obtained perovskite layer is substantially enhanced, showing fewer defects and a superior morphology. As a result, the air-deposited devices exhibit higher efficiency, which, combines with the enhanced AVT, results in a champion device with a light use efficiency (LUE) of 4.2%, having a PCE of 13.8% and AVT of 30.4%. The record LUE value and the possibility of being deposited in ambient air conditions pave the avenue toward the real-world application of semi-transparent PSCs.

High throughput computational screening and interpretable machine learning for iodine capture of metal-organic frameworks

The removal of leaked radioactive iodine isotopes in humid air environments holds significant importance in nuclear waste management and nuclear accident mitigation. In this study, high-throughput computational screening and machine learning were combined to reveal the iodine capture performance of 1816 metal-organic framework (MOF) materials under humid air conditions. Initially, the relationship between the structural characteristics of MOF materials (including density, surface area and pore features) and their adsorption properties was explored, with the aim of identifying the optimal structural parameters for iodine capture. Subsequently, two machine learning regression algorithms—Random Forest and CatBoost, were employed to predict the iodine adsorption capabilities of MOF materials. In addition to 6 structural features, 25 molecular features (encompassing the types of metal and ligand atoms as well as bonding modes) and 8 chemical features (including heat of adsorption and Henry’s coefficient) were incorporated to enhance the prediction accuracy of the machine learning algorithms. Feature importance was assessed to determine the relative influence of various features on iodine adsorption performance, in which the Henry’s coefficient and heat of adsorption to iodine were found the two most crucial chemical factors. Furthermore, four types of molecular fingerprints were introduced for providing comprehensive and detailed structural information of MOF materials. The 20 most significant Molecular ACCess Systems (MACCS) bits were picked out, revealing that the presence of six-membered ring structures and nitrogen atoms in the MOF framework were the key structural factors that enhanced iodine adsorption, followed by the presence of oxygen atoms. This work combined high-throughput computation, machine learning, and molecular fingerprints to comprehensively and systematically elucidate the multifaceted factors governing the iodine adsorption performance of MOFs in humid environments, establishing a robust and profound guideline framework for accelerating the screening and targeted design of high-performance MOF materials.

Encountering graffiti and street art under light and air conditions: Exploring the atmospheric qualities of a place

Encountering graffiti and street art under light and air conditions: Exploring the atmospheric qualities of a place

A controllable and fast carbonization strategy under air conditions and its application in electromagnetic interference (EMI) shielding

A controllable and fast carbonization strategy under air conditions and its application in electromagnetic interference (EMI) shielding

π-Stacked organic heterojunction enabled efficient hydrogen peroxide photoproduction.

π-Stacked organic heterojunction enabled efficient hydrogen peroxide photoproduction.

Scaling Criteria for Wall Thermal Boundary Conditions of Air- and Water-Cooled Free Convective Thin Plates with Volumetric Heat Generation

Scaling Criteria for Wall Thermal Boundary Conditions of Air- and Water-Cooled Free Convective Thin Plates with Volumetric Heat Generation

Predicting process and regeneration air conditions in LT3 molecular sieve desiccant wheels using machine learning and regression methods

Predicting process and regeneration air conditions in LT3 molecular sieve desiccant wheels using machine learning and regression methods

Enhanced Stability of Quaternary Ammonium Cross‐Linked SEBS Anion Exchange Membranes for Fuel Cells

AbstractA novel alkaline anion exchange membrane was designed using poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) as the backbone. Long side chains were grafted onto SEBS via a Friedel‐Crafts reaction, and a cross‐linked membrane (SEBS‐C6‐DiPRD) was prepared using an N‐heterocyclic crosslinker, 1,3‐N‐4‐piperidinyl propane, which features ring strain and steric hindrance. The prepared SEBS‐C6‐DiPRD membrane exhibited an ion exchange capacity of approximately 1.8 mmol·g−1, a water uptake of 85.4%, and a swelling ratio of 24.1% at 80 °C. Thermal degradation began at 370 °C, and the membrane broke at a strain of 310.6% and a stress of 31.1 MPa. At the operating temperature of 80 °C (typical for AEMFCs), the conductivity reached 75.95 mS·cm−1. Notably, after 1000 hours of testing under simulated AEMFC conditions, the membrane's conductivity only decreased by 27.6%, demonstrating excellent long‐term stability. Under H2 and air conditions, the peak power density of the SEBS‐C6‐DiPRD membrane was 18.89 mW·cm−2.

Enhancing Indoor Photovoltaic Efficiency to 37.6% Through Triple Passivation Reassembly and n‐Type to p‐Type Modulation in Wide Bandgap Perovskites

AbstractDespite well‐matching indoor illumination spectra, the performance of wide bandgap perovskite solar cells (WB‐PSCs) for indoor photovoltaics (i‐PV) is hindered by photo‐induced halide phase segregation and trap‐assisted non‐radiative recombination. Herein, a Triple Passivation Treatment (TPT) reassembly strategy is presented to simultaneously suppress bulk and surface defects. TPT induces a transition in perovskite surface energetics from n‐type to p‐type and remarkably increases the photoluminescence quantum yield from 0.5 to 2.1%, creating a more favorable band alignment for hole extraction whilst substantially reducing halide phase segregation. As a result, 1.75 eV WB‐PSCs achieve an indoor Power Conversion Efficiency (iPCE) of 37.6% under 1000 lux illumination. Under standard sunlight conditions, the devices reach a Power Conversion Efficiency (PCE) of 20.1% and a fill factor of 78.5%, among the best performance parameters for this bandgap. Importantly, the passivated devices exhibit excellent shelf stability, retaining 92% of their initial performance after 3200 h. Under ambient air conditions at 55 °C, the unencapsulated devices maintained 76% of their initial PCE after 300 h continuous light soaking. The findings represent a significant breakthrough in the development of stable WB‐PSCs for i‐PV applications, with minimized nonradiative losses and enhanced performance.

Large Stokes-Shifted Photoluminescence of Sulfur-Containing Imide Compounds and Polyimides Induced by Transient Conformational Changes upon Excitation.

The optical absorption and photoluminescence (PL) properties of a series of sulfur-containing semialicyclic polyimides (S-PIs) were examined to develop thermally stable functional polymers with high glass transition temperatures, high optical transparencies, and large Stokes-shifted PL. These S-PIs were synthesized using tetracarboxylic dianhydrides, including thioether (-S-) linkages, such as 4,4-thiodiphthalic anhydride (SDPA), 4,4'-[p-phenylenebis(thio)]diphthalic anhydride (2SDEA), 4,4'-[p-thiobis(phenylene sulfanyl)] diphthalic anhydride (3SDEA), and trans-1,4-cyclohexanediamine (1,4-tDACH). In addition, the optical and PL properties of three types of imide model compounds (MCs) were investigated. All the S-PI films exhibited blue or green fluorescence (FL) under ambient conditions (in air at 295 K), weak room temperature phosphorescence (RTP) under vacuum, and bright green phosphorescence (PH) at lower temperatures (∼77 K). The intersystem crossing (ISC) rates at 77 K were significantly higher than those of the polyimides containing diphenyl-ether (-O-) linkages, primarily due to the enhancement of ISC by the heavy-atom effect of the sulfur atoms. MCs with multiple thioether (-S-) linkages exhibited a peculiar green or greenish-yellow FL with very large Stokes shifts in the CHCl3 solution. This behavior was due to the transient conformational change from the kinked structure in the ground state to a skewed structure in the excited singlet state. In addition, all the MCs dispersed in a poly(methyl methacrylate) matrix exhibited distinctive RTP owing to the restricted conformational changes in the rigid matrix. These results provide effective guidelines for designing polymers exhibiting large Stokes-shifted FL and PH at longer wavelengths in the visible region.

Implementation of Decision Tree Algorithm for Activity Recommendations Based on Air Quality Index (AQI) and PM2.5 Pollution in Indonesia

The increasing air pollution in major cities across Indonesia has raised serious public health concerns. This research aims to develop a recommendation system for daily activities based on the Air Quality Index (AQI) and PM2.5 levels. Using the Decision Tree algorithm, this study categorizes air quality conditions and provides appropriate activity recommendations, such as whether it is safe to exercise outdoors or if it is better to stay indoors. The model utilizes AQI and PM2.5 data collected from various Indonesian cities. The results indicate that the Decision Tree algorithm is effective in providing accurate activity recommendations based on air quality, demonstrating significant accuracy in classifying air conditions. The implementation of this system is expected to aid individuals in making informed decisions about their daily activities, thereby mitigating health risks associated with air pollution exposure. The urgency of this research lies in the need for a more adaptive and personalized system to provide activity recommendations based on real-time air quality data. Amid the rising cases of respiratory illnesses and diseases related to air pollution exposure, this study plays a crucial role in supporting a healthier and safer lifestyle. In addition, the implementation of this system can serve as a foundation for public policy and environmental risk mitigation strategies that are more data-driven and technology-based in the future.

High-Oriented SnO2 Nanocrystals for Air-Processed Flexible Perovskite Solar Cells with an Efficiency of 23.87.

Tin (IV) oxide (SnO2) electron transport layer (ETL) emerges as the most promising n-type semiconductor material for flexible perovskite solar cells (f-PSCs). The (110) facet-dominated SnO2 colloids are readily created, whereas other best-performing (101) and (200) facets-dominated ones with superior potential in interface modulation and lattice matching remain insufficiently explored. Here water-soluble acryloyloxyethyltrimethyl ammonium chloride-acrylamine (DAC-AA) doping into SnO2 colloids produces more (101)- and (200)-oriented crystal domains through lowering surface absorption energy and offering additional thermodynamic driving force. Theoretical and experimental analyses corroborate that the grain preference orientation induced by DAC-AA modification strengthens heating transfer rate on the flexible substrate and favors lattice matching of perovskite (100) plane on SnO2 (101) and (200) facets. Accordingly, the champion f-PSCs on high-oriented SnO2-DAC-AA ETLs fabricated fully in ambient air conditions achieve the efficiencies of 23.87% and 22.41% with aperture areas of 0.092 and 1 cm2. In parallel, the propitious interfacial lattice arrangement attenuates the formation of micro-strain inside perovskite films, maintaining 92.5% of their initial performance after 10000 bending cycles with a curvature radius of 6mm.

Maintaining Visual Quality and Fresh, Firm Texture during Countertop Ripening of Peaches, Guava, and Passionfruit With Vented Containers

Peaches, guavas, and passionfruits ripen best at room temperature (68 to 73.4 °F/20 to 23 °C) and high relative humidity (RH) (> 85%), however, the RH of an air-conditioned home is typically < 50% which accelerates desiccation. This project explored ripening these fruits under a passive system to generate high RH to investigate potential quality benefits. The high RH environment was generated by trapping water vapor from the ripening fruit inside a lidded, 5-L plastic container, vented with 225 holes of 3.4 mm² evenly distributed across the lid in a 15 × 15 grid. Fruit were stored in these lidded containers or on open trays from 3 to 8 days at 69.8 °F (21 °C) and 50% RH, simulating an air-conditioned kitchen environment. Once the fruit stored in open air were ripe and ready to eat, fruit from both treatments were evaluated. RH in the vented containers for guava and passionfruit was maintained at 92 to 94% and that in containers storing peach was 96 to 99%. Storage of peaches, passionfruits, and guavas in the vented containers prevented visually-evident shriveling and delayed ripening-associated softening compared to those that were stored under low RH conditions in ambient air. Peaches stored in high RH were firmer (20 N), than those in low RH (8–10 N), as were guavas (30–35 N and < 20 N), respectively. Weight loss for all fruit stored in high RH was much less (2 to 4%), compared with fruit stored in open air (13 to 25%), depending on the crop. Other benefits of ripening in the vented containers were that guava fruit maintained peel sheen, whereas that of fruit ripened under low RH became matte and dull; the peel of container-ripened peaches remained taut and fresh while that of peaches ripened on the simulated countertop became shriveled and visually undesirable. Therefore, storage in a passive system capable of maintaining a high RH, non-condensing environment can prevent shrivel and maintain visual and tactile quality of peaches, guavas, and passionfruits under typical air-conditioned conditions.

Effect of sustainable cooling and lubrication method on the hole quality and machinability performance in drilling of AA7075 alloy with cryogenically treated carbide drills

Abstract The present study examines the machinability performance of AA 7075 alloy under dry, air, and MQL-assisted machining conditions with cryogenically treated drills. The machinability performance of the AA 7075 alloy was evaluated in terms of surface roughness, cutting temperature, tool wear, deviation from diameter and circularity. Drilling tests were created using the Taguchi Taguchi L18 index. The cutting tool, cutting environments (dry, air and MQL), cutting speed, and feed rate were selected as drilling parameters. The data obtained from the drilling experiments were subjected to statistical analysis using the following techniques: signal-to-noise ratio (SNR), variance (ANOVA), and regression. The outcomes of this study show that cryogenic treatment increases the microhardness of tungsten carbide drills and positively affects machinability performance characteristics. It was also determined that surface roughness, cutting temperature, deviation from diameter and circularity values were approximately 99.81 %, 27 %, 38 %, and 40 % lower in air-assisted machining conditions and approximately 33.62 %, 30 %, 42 %, and 50 % lower in MQL-assisted machining conditions, respectively, compared to dry-machining condition. Moreover, SEM examination shows that the dominant wear mode for the cutting tools is built-up chipping (BUE) and negligible tool chipping occurs.

Experimental and numerical investigation on heat dissipation capability of micro-pillar textured cutting tools

In metal cutting, the extreme tool temperature restricts the material removal rate. To address this, it is crucial to adopt techniques that reduce heat input and enhance heat dissipation from the cutting tool inserts. Rake surface texturing, particularly with micro-pillars, is gaining popularity in this context. Direct measurement of the cutting tool temperature is exceptionally challenging, so a numerical approach is adopted in this work to inverse estimate the tool tip temperature based on the temperature measured at a distant location from the rake face. Stage I of the work involved the development of a circular micro-pillar array on tungsten carbide inserts using the Reverse Micro Electrical Discharge Machining (RµEDM) technique. Based on the discharge pulses recorded during RµEDM, the 110V–100 nF voltage-capacitance combination proved feasible for this operation. In Stage II, turning operations were performed on Ti6Al4V alloys under dry, compressed air, and wet conditions. The tool temperature measured at the distant location revealed a substantial temperature drop for textured tools. This is attributed to the reduced contact area at the interface, as observed from the rake morphology of the tools, and to the enhanced heat dissipation from the higher surface area of the developed textures, as revealed by the computational fluid dynamics-based numerical study in Stage III of the work. An array of closely spaced, small-diameter, and higher-depth micro-pillars beyond the tool-chip contact area could enhance heat dissipation from the cutting tools.

Thermal Evaluation of Biocomposites Made from Poly(Lactic Acid) and Cottonseed Byproducts

Poly(lactic acid) (PLA) is derived from sugar-based materials. While it is a leading sustainable biopolymer, PLA has been integrated with other agricultural coproducts (e.g., lignin, protein, and starch) to reduce its cost and enhance its modulus and biodegradability. Cottonseed oil and meal are the byproducts of the cotton fiber industry. In this work, four biocomposites were formulated with PLA, cottonseed oil, washed cottonseed meal, and plasticizing reagent glycerol with different formulation ratios. The thermal degradation behaviors were examined via thermogravimetric (TG) analysis under air and nitrogen conditions with the neat PLA sample as a control. The thermal decomposition characteristic values were impacted by both the biocomposite formulation and the heating rates of 1, 2, 5, and 10 °C min−1. Results from two kinetic modeling methods that were examined indicated that the activation energy was relatively steady for the neat PLA in the whole degradation process. Generally, the low activation energy values of biocomposites other than PLA under nitrogen conditions implied that these cottonseed byproduct constituents promote the thermal decomposition of these biocomposites. However, the presence of oxygen would confound the thermal decomposition of the biocomposites, as shown by variable activation energy curves with higher values under air conditions. TG-FTIR analysis revealed that the major gaseous compounds were carbonyl, carbon dioxide, carbon monoxide, methane, and water, which were derived from the thermal decomposition of the biocomposites.

Air-Processed Perovskites Enabled by an Interface-Reconstruction Strategy for High-Performance Light-Emitting Diodes.

Fabricating high-performance perovskites in ambient air is desirable for low-cost and large-scale patterned manufacture of light-emitting diodes (LEDs). However, perovskites inherently exhibit high sensitivity to moisture and oxygen, which considerably hinders their fabrication under ambient air conditions. Here, we demonstrated an interface-reconstruction strategy which enabled air-processed CsPbI3 quantum dot (QD) films for high-performance LEDs. Ethyl acetate/tris(1-naphthyl)phosphine oxide (EA/TNPO) treatment was used to polish and passivate the interface between the QD film and the electron transport layer, thereby providing a protective coating against moisture and oxygen. We fabricated LEDs based on the spin-coated QD films, achieving a maximum external quantum efficiency (EQE) of 20.2% and a long half-life of over 100 days. We also fabricated LEDs based on the inkjet-printed QD films, highlighting the practical application potential for patterning techniques. Our work develops high-quality air-processed perovskite films and demonstrates their great prospect for low-cost optoelectronic devices in the future.

Combustion of Polycarbonate and Polycarbonate–Carbon Nanotube Composites Using Fluidized Bed Technology

This study investigates the combustion behavior of polycarbonate (PC) and polycarbonate–carbon nanotube (PC-CNT) composites in fluidized bed reactors. The primary objective was to evaluate the influence of carbon nanotubes (CNTs) on the thermal stability and combustion efficiency of PC. Simultaneous thermogravimetric and differential scanning calorimetry (TG-DSC) analyses were conducted under both air and oxygen-deficient conditions to assess decomposition temperature ranges and energetic effects. Additionally, a simultaneous TG-DSC analysis of the samples’ decomposition in a 2 vol.% O2 atmosphere was carried out to simulate adverse combustion conditions that may occur in some combustion technologies, such as the accumulation of degraded material on the grate. Combustion experiments were performed in inert and catalytic fluidized beds, the latter incorporating Fe2O3-coated cenospheres to enhance catalytic activity. The results demonstrated that the presence of CNTs alters the combustion mechanism, reducing energy release in the initial degradation stage while significantly intensifying exothermic effects in subsequent stages. Under oxygen-deficient conditions, both PC and PC-CNT required higher temperatures and extended times for complete decomposition. The catalytic fluidized bed markedly improved combustion efficiency at lower temperatures, achieving up to 90% conversion at 550 °C, compared to inert beds that required 750 °C for similar efficiency.

Two‐Step Inverted Perovskite Solar Cells with > 25% Efficiency Fabricated in Ambient Air

AbstractThe two‐step method for perovskite solar cells (PSCs) offers a promising technology for scalable manufacturing, particularly under ambient air conditions, due to its inherent simplicity, high reproducibility, and operational convenience. With this approach, achieving high‐quality of lead iodide (PbI2) films during the initial stage is paramount to ensuring the overall performance and stability of the devices. However, during the ambient fabrication of PbI2, the residual high boiling point and hygroscopic dimethyl sulfoxide (DMSO) solvent significantly compromises the resulting film quality. Here, L‐Homoarginine hydrochloride (HargCl) is introduced into the PbI2 precursor solution, which greatly reduced the residual amount of PbI2·xDMSO and passivated the internal defects of perovskite (PVK) films. By leveraging this strategy, inverted perovskite solar cells entirely in the air are successfully prepared, achieving an impressive power conversion efficiency (PCE) of 25.05% — the highest reported efficiency to date for two‐step fully air‐processed inverted PSCs. In addition, these unencapsulated devices maintained 96% of their initial power conversion efficiency after 500 h storage in the air with 20–40% RH.