Search

Radiative sky cooling is a promising passive cooling technology that dose not consume energy or produce greenhouse gas. It has been extensively studied in the past decades. However, its relatively low cooling power (∼100 W m−2) presents a significant barrier to its commercial deployment. For broader applications, integrating phase change and evaporative cooling can significantly enhance the cooling performance and temperature control capabilities of radiative sky cooling. In this review, we summarize the recent advances in hybrid cooling achieved by incorporating radiative cooling with phase change cooling or evaporative cooling. The regulatory mechanism of hybrid cooling is first discussed to reveal the detailed working principle. Subsequently, the structure form and cooling performance of hybrid cooling are summarized to fully clarify the core points of material design and highlight their benefits. In addition, the application scenarios of hybrid cooling are further discussed to underline their promising application potential. Last but not least, the challenges and prospects are presented to advance the commercial application of hybrid cooling. [ABSTRACT FROM AUTHOR]

Refrigeration technology plays a critical role in various aspects of daily life and industrial production. However, traditional refrigeration methods consume substantial energy and cause environmental pollution, hindering their ability to meet future refrigeration requirements. Radiative cooling as a refrigeration technology that does not require an external energy input has garnered significant attention owing to its energy-saving and environmentally friendly characteristics. In recent years, substantial advancements in radiative cooling technology have been made, ranging from improved cooling capacity to enhanced control over cooling effects and increased durability. Presently, radiative cooling technology has matured to the point where its practical applications have become feasible. Herein, we provide a comprehensive overview of radiative cooling technology, covering its basic principles, various design structures, and potential applications. Additionally, the current challenges associated with this technology are highlighted, aiming to offer essential suggestions for its future progress and improvement. [ABSTRACT FROM AUTHOR]

The chemical adsorption was found to occur between aluminium and organic corrosion inhibitors, and lone pairs of electrons of N, O and S of functional groups on the organic compounds were shown to mediate the formation of bonds to produce films on aluminium. The corrosion inhibition rates of the films formed by aniline, thiourea, and n-butanol organics were found to be 46.62%, 64.88% and 49.52%, respectively. [ABSTRACT FROM AUTHOR]

Controlled crystallization, melting and vitrification are important fundamental processes in nature and technology. However, the microscopic details of these fundamental phenomena still lack understanding, in particular how the cooling rate and presence of a wall influence the crystal nucleation and glass formation. Thermoresponsive microgels provide the possibility to study phase transitions at the single-particle level, owing to the ability to tune the particle size with temperature. In this study, we employ composite microgels consisting of a hard core and a crosslinked poly( N -isopropyl acrylamide- co -methacrylic acid) shell to study the crystallization of dense suspensions of soft colloids near a wall using confocal microscopy. We investigate the effect of the cooling rate on the fluid-to-solid transition close to the sample wall. The structures formed during cooling range from glassy in the case of a rapid temperature quench to crystalline when a slow cooling rate is used. Detailed analysis of the final structure reveals that the cooling rate also sets the degree of alignment of the crystal domains with the wall as a result of a balance between homogeneous and heterogeneous crystal nucleation. The results presented here yield valuable insight into the microscopic details of temperature-controlled crystallization near a wall. This understanding will help pave the way towards optimal crystallization conditions for microgel applications.

We show distinct CH-π interactions and assembly pathways for the amphiphile N -(fluorenylmethoxycarbonyl)-galactosamine and its epimer N -(fluorenylmethoxycarbonyl)-glucosamine. These differences result in the formation of supramolecular nanofibrous systems with opposite chirality. Our results showcase the importance of the carbohydrates structural diversity for their specific biointeractions and the opportunity that their ample interactome offers for synthesis of versatile and tunable supramolecular (bio) materials.

Passive radiative cooling (PRC), as an energy-free cooling approach, is ingeniously harnessed for certain natural organisms to withstand extreme high-temperature climates, which has inspired numerous bionic designs. However, it is a great challenge to enhance the durability of the designed materials in practical scenarios while inheriting the natural biological principles. We demonstrate bionic dual-scale structured (BDSS) films for efficient passive radiative cooling accompanied by robust durability after discovering the excellent thermoregulatory properties of the inner surface of Hawaiian scallop shell. We found that the inner surface of the shell consists of large-scale triangular ridges scattered with small-scale terrace steps. This dual-scale structure can enhance the reflectivity of sunlight by efficient Mie scattering and increase the emissivity in the mid-infrared range by lengthening the propagation of photons, thereby decreasing the surface temperature. Underpinned by this finding, we developed a BDSS film that features a strong solar spectrum reflectivity of 0.95 and a high mid-infrared emissivity of 0.98, achieving a sub-ambient cooling of 10.8 °C under direct sunlight. Additionally, the designed films possess robust durability including excellent self-cleaning, flexibility, mechanical strength, chemical stability, and anti-ultraviolet radiation, which is promising for thermal thermoregulation in various harsh scenarios.

The radiative cooling of naphthalene dimer cations, (C 10 H 8 ) 2 was studied experimentally through action spectroscopy using two different electrostatic ion-beam storage rings, DESIREE in Stockholm and Mini-Ring in Lyon. The spectral characteristics of the charge resonance (CR) band were observed to vary significantly with a storage time of up to 30 seconds in DESIREE. In particular, the position of the CR band shifts to the blue, with specific times (inverse of rates) of 0.64 s and 8.0 s in the 0-5 s and 5-30 s storage time ranges, respectively. These long-time scales indicate that the internal energy distribution of the stored ions evolves by vibrational radiative cooling, which is consistent with the absence of fast radiative cooling + was studied experimentally through action spectroscopy using two different electrostatic ion-beam storage rings, DESIREE in Stockholm and Mini-Ring in Lyon. The spectral characteristics of the charge resonance (CR) band were observed to vary significantly with a storage time of up to 30 seconds in DESIREE. In particular, the position of the CR band shifts to the blue, with specific times (inverse of rates) of 0.64 s and 8.0 s in the 0-5 s and 5-30 s storage time ranges, respectively. These long-time scales indicate that the internal energy distribution of the stored ions evolves by vibrational radiative cooling, which is consistent with the absence of fast radiative cooling via recurrent fluorescence for (C 10 H 8 . Density functional based tight binding calculations with local excitations and configuration interactions (DFTB-EXCI) were used to simulate the absorption spectrum for ion temperatures between 10 and 500 K. The evolution of the bandwidth and position with temperature is in qualitative agreement with the experimental findings. Furthermore, these calculations yielded linear temperature dependencies for both the shift and the broadening. Combining the relationship between the CR band position and the ion temperature with the results of the statistical model, we demonstrate that the observed blue shift can be used to determine the radiative cooling rate of (C 2 + . Density functional based tight binding calculations with local excitations and configuration interactions (DFTB-EXCI) were used to simulate the absorption spectrum for ion temperatures between 10 and 500 K. The evolution of the bandwidth and position with temperature is in qualitative agreement with the experimental findings. Furthermore, these calculations yielded linear temperature dependencies for both the shift and the broadening. Combining the relationship between the CR band position and the ion temperature with the results of the statistical model, we demonstrate that the observed blue shift can be used to determine the radiative cooling rate of (C 10 H 8 ) 2 + .

Daytime passive radiative cooling devices expel heat into the cold outer space by thermal radiation, offering an energy-efficient strategy for cooling terrestrial objects. Colored coolers are more desirable than white ones in real-world applications under the demands of aesthetics and reducing light pollution. The recently proposed fluorescence-assisted methods based on phosphor powders have simultaneously achieved sub-ambient cooling performance and bright colors, ascribed to the fluorescence-induced heat gain offset and consequent high-effective solar reflectance. However, the color gamut of radiative coolers is still limited due to the lack of blue colors, attributed to the absorption of the majority of visible light. In this work, we propose and prepare a light-blue radiative cooling coating composed of a ZrO2 white bottom layer with a remarkable high solar reflectance of >98% and an ultra-thin top layer consisting of a blue phosphor (SrO·Al2O3: Eu). This bilayer coating reveals a high effective solar reflectance of 94% with a vivid light-blue appearance and achieves a sub-ambient temperature reduction of 3–4.4 °C under a peak solar intensity of >800 W m−2 and an average humidity of 30% in Hong Kong. Our work paves the way for fabricating highly efficient radiative cooling coatings with a whole gamut of tunable colors. [ABSTRACT FROM AUTHOR]

L -Menthol is one of the most important flavouring and additive agents found naturally in plants (mint family). In the present work, the polymorphic separation of L -menthol from saturated aqueous solution is carried out through a swift cooling crystallization process with varying relative supersaturation conditions σ = 2.36 to 7.3. Nucleation of the form-II polymorph of L -menthol is observed with varying induction times throughout the experiment and the nucleation, morphology and growth behaviour were demonstrated using optical microscopy. The nucleation kinetics of L -menthol based on classical nucleation theory was studied using the experimentally obtained induction time and relative supersaturation. Further, the internal structure and thermal stability of the grown crystal were confirmed by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses. [ABSTRACT FROM AUTHOR]

Flexible electronics has been widely recognized as the future of electronics for a broad range of applications, which is also the foundation for wearable devices that can go on or even seamlessly integrate with the human skin. With the development of device miniaturization, diverse environmental operation and power density enhancement, people have realized the significance of thermal management in flexible electronics. Traditional thermal management methods that rely on active cooling systems often require the use of extensive power and bulk instruments, which consequently restricts the wearability and portability of the devices. Recent breakthroughs in passive cooling materials (PCMs) have offered advanced thermal management solutions for flexible electronics, enabling more opportunities for wearable devices in the fields of medicine, communication, entertainment and many others. This review concentrates on the fundamental principles of PCMs and their recent advances in both materials and devices for flexible electronics. Additionally, we explore potential applications of flexible electronics equipped with passive cooling interfaces in various scenarios, with a special focus on technological feasibility and benefits. We also provide an in-depth discussion on the challenges and prospective solutions for passive thermal management to enhance future cooling techniques. [ABSTRACT FROM AUTHOR]

To meet the increasing need for outdoor personal thermal management (PTM) since the intensified global warming, radiative cooling (RC) textiles with tunable solar reflectivity and mid-infrared emissivity/transmissivity attributes can dynamically adjust the microenvironment of the human body to provide a cooling effect without consumption of electrical energy, in contrast to the traditional heat preservation function of commercial clothes. In this review, we summarize recent advances in RC textiles from basic mechanisms, construction methods to emerging applications. The underlying mechanisms of optical absorption/reflection and heat emission properties and typical efficient structures are first discussed to comprehend the principles of RC techniques. The corresponding construction strategies for modifying textile materials and structures for improved passive cooling performance are then highlighted. The various applications of RC textiles are also reviewed to demonstrate their practicability and versatility, such as smart clothing, object cooling, enhanced electricity generation, etc. Eventually, we will give a brief outlook on the current challenges and future development of RC textiles. This review intends to provide a better understanding of RC techniques for functional textile design and fabrication. [ABSTRACT FROM AUTHOR]

Nucleation control and isolation of polymorphic forms of the essential pharmaceutical medicine aspirin (ASP) was examined by a supersaturation-dependent swift cooling crystallization process using acetonitrile as solvent. In the present investigation, a saturated solution was prepared at 323 K and swiftly cooled down to various temperatures below the equilibrium temperature in steps of 1 K by conducting a series of 49 systematic cooling experiments which gave a very clear nucleation matrix, indicating the preferred nucleation region of all the three polymorphic forms of aspirin under different supersaturation conditions in the range 0.20 < σ < 1.65. Moreover, an observed solution-mediated polymorphic phase transformation (SMPT) under specific supersaturation conditions (σ = 0.97) indicates that the dissolution of characteristic faces {1¯ 0 2} and {1¯ 1 1} occurs in the grown metastable form-II, and the characteristic face {0 0 2¯} of form-I simultaneously nucleates and grows over form-II in the −c and +c crystallographic directions on the surface of form-II. This discovery may provide a better understanding of the intergrowth phenomenon of aspirin polymorphs. The occurrence of this peculiar phenomenon was further ensured by attachment energy calculations, morphology assessment, and relative area analyses. Also, the nucleation kinetics of the grown ASP polymorphs were evaluated using the experimentally obtained induction time and calculated supersaturation values, by the classical nucleation theory (CNT) approach, and these results are well matched with the obtained experimental results. The structural and phase stability of the grown polymorphs were ascertained by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses. [ABSTRACT FROM AUTHOR]

Photothermal regulation concerning solar harvesting and repelling has recently attracted significant interest due to the fast-growing research focus in the areas of solar heating for evaporation, photocatalysis, motion, and electricity generation, as well as passive cooling for cooling textiles and smart buildings. The parallel development of photothermal regulation strategies through both material and system designs has further improved the overall solar utilization efficiency for heating/cooling. In this review, we will review the latest progress in photothermal regulation, including solar heating and passive cooling, and their manipulating strategies. The underlying mechanisms and criteria of highly efficient photothermal regulation in terms of optical absorption/reflection, thermal conversion, transfer, and emission properties corresponding to the extensive catalog of nanostructured materials are discussed. The rational material and structural designs with spectral selectivity for improving the photothermal regulation performance are then highlighted. We finally present the recent significant developments of applications of photothermal regulation in clean energy and environmental areas and give a brief perspective on the current challenges and future development of controlled solar energy utilization. [ABSTRACT FROM AUTHOR]

Combining cooling and antisolvent modes of crystallization is advantageous as it may significantly improve the process performance. A set of experiments were conducted on combined cooling and antisolvent crystallization of L -asparagine monohydrate (LAM) in water/isopropanol mixture. Due to its size, the LAM crystals were represented by two characteristic dimensions (length and width) and a two-dimensional population balance equation (PBE) for the system was developed to predict the evolution of crystal size distribution (CSD). The measured solute concentration and size distribution data were used to estimate the nucleation and growth kinetics by solving the population balance model combining with a nonlinear optimization technique. The nucleation rate and birth rate were described by classical nucleation theory and BCF model, respectively. The high resolution finite volume discretization scheme with a flux limiter was used to solve the PBE for simulating the crystallization process. The estimated parameters predict the time evolution of concentration and CSD reasonably well for all the cases studied. [ABSTRACT FROM AUTHOR]

We demonstrate here that the synergistic utilization of cascaded space time based on the quality attributes of different radiation energies is an enhanced mechanism for maximizing 24 hour production of clean electricity from the sun and outer space. Here, a photovoltaic thermoelectric radiation cooling system is proposed. The photovoltaic, thermoelectric generator, and outer space are coupled in reverse order through a photothermal connection layer and a thermal conductivity enhanced radiation cooling composite film. By utilizing radiation energy concentration, energy coupling cascading utilization, and spatial reverse coupling to reduce time space temperature conflicts, the performance of the most advanced solar radiation cooling generator is improved by nearly ten times. The proposed photovoltaic-thermoelectric-radiative cooling system achieves an impressive maximum power density of 213.1875 W m−2. The maximum power of thermoelectric generator during daytime and nighttime are 20.425 W m−2 and 1.56 W m−2, respectively. In addition, the heat capacity and various energy generation methods of the composite system have improved system performance and resistance to weather changes. These results promote an understanding of the complex energy quality coordination mechanism for efficient power generation using renewable thermal resources from both the sun and outer space, and contribute to its future design. [ABSTRACT FROM AUTHOR]

The distribution of impurities within aggregates is crucial for managing overall impurity levels and enhancing product quality. However, current detection methods often fall short to provide accurate information. This paper presents a novel fluorescence-staining method for effective solvent tagging within crystals, which can enhance impurity management. [ABSTRACT FROM AUTHOR]

Accurate knowledge of the heating performance of magnetic nanoparticles (MNPs) under AC magnetic fields is critical for the development of hyperthermia-mediated applications. Usually reported in terms of the specific loss power (SLP) obtained from the temperature variation (Δ T ) vs. time ( t ) curve, such an estimate is subjected to a huge uncertainty. Thus, very different SLP values are reported for the same particles when measured on different equipment/in different laboratories. This lack of control clearly hampers the further development of nanoparticle-mediated heat-triggered technologies. Here, we report a device-independent approach to calculate the SLP value of a suspension of magnetic nanoparticles: the SLP is obtained from the analysis of the peak at the AC magnetic field on/off switch of the Δ T (time) curve. The measurement procedure, which itself constitutes a change of paradigm within the field, is based on the heat diffusion equation, which is still valid when the assumptions of Newton's law of cooling are not applicable, as (i) it corresponds to the ideal scenario in which the temperature profiles of the system during heating and cooling are the same; and (ii) it diminishes the role of coexistence of various heat dissipation channels. Such an approach is supported by theoretical and computational calculations to increase the reliability and reproducibility of SLP determination. Furthermore, the new methodological approach is experimentally confirmed, by magnetic hyperthermia experiments performed using 3 different devices located in 3 different laboratories. Furthermore, the application of this peak analysis method (PAM) to a rapid succession of stimulus on/off switches which results in a zigzag-like Δ T ( t ), which we term the zigzag protocol, allows evaluation of possible variations of the SLP values with time or temperature., Competing Interests: C. Jones works for Nanotherics, a company that produces devices to characterize the heating performance of magnetic nanoparticles., (This journal is © The Royal Society of Chemistry.)

A rheo-microscopy in situ synchronous measurement system was utilized to investigate the dynamic behavior of water droplets in W/O waxy crude oil emulsions subjected to dynamic cooling conditions, the microstructural evolution of water droplets aggregates can be categorized into three stages based on the various forms of wax crystals. The results show that under the joint action of wax crystals and water droplets, the water droplets aggregation trend and complexity in the system are negatively correlated with the changes of temperature and shear rate, and the water droplets movement behavior is positively correlated with the changes of temperature and shear rate. As the temperature decreases, the minimum edge distance of water droplets decreases by a maximum of 32.1%, the specific surface area (SA) decreases by a maximum of 12.0%, and the fractal dimension increases by a maximum of 11.7%. As the shear rate increases, the minimum edge distance of water droplets increases by up to 27.9%, the specific surface area (SA) increases by up to 10.1%, and the fractal dimension decreases by up to 8.5%. Additionally, an analysis is conducted on the collision aggregation behavior of water droplets in shear flow field based on population balance theory., Competing Interests: There is no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Passive radiative cooling (PRC) that realizes thermal management without consuming any energy has attracted increasing attention. Unfortunately, polymer fibers with radiative cooling function fabricated via a facile, continuous, large-scale and eco-friendly method have been scarcely reported. Herein, polyethylene fibers containing directional microchannels (PFCDM) are facilely fabricated via melt extrusion and water leaching. Interestingly, fabric based on such hydrophobic PFCDM shows high sunlight reflectivity (93.6%), and mid-infrared emissivity (93.9%), endowing it with remarkable PRC performance. Compared with other reported examples, the as-prepared PFDCM fabric has the highest cooling power ( i.e. , 104.285 W m -2 ) and temperature drop ( i.e. , 27.71 °C). Furthermore, decent self-cleaning performance can keep the PFCDM fabric away from contamination and enable it to retain an excellent radiative cooling effect. The method proposed to fabricate PFCDM in this paper will widen the potential application of thermoplastic polyolefins in the field of radiative cooling.

Passive daytime radiative cooling (PDRC) has been widely used in environmental protection, energy conservation and cooling. However, most PDRC designs primarily focused on improving the daytime cooling effect while ignoring the problem of nighttime overcooling. Here, we designed a flexible and multifunctional composite film doped with rare earth phosphors, which has high solar reflectivity and high infrared emissivity. During the daytime, it realizes subambient cooling of ≈11 °C at an average solar radiation density of 827.74 W m−2. Remarkably, it addresses the problem of nighttime overcooling by maintaining a minimal temperature difference of only 0.5–1.5 °C. Moreover, the rare earth phosphors doped in our design not only effectively compete with titanium dioxide nanoparticles for ultraviolet absorption during the day, but also exhibit significant luminescence at night, providing a useful color reminder effect. These findings highlight the exceptional properties of the radiative cooler and promote its applications in a variety of fields. [ABSTRACT FROM AUTHOR]

Slowing hot carrier (HC) cooling in lead halide perovskites is important to further improve the efficiency of perovskite solar cells (PSCs). Herein, we found that HC cooling can be efficiently prolonged by incorporating an organic small molecule (TDGA) into the perovskite film as an additive through transient absorption spectroscopy measurements, which is conducive to the extraction of the HC energies by the carrier transport layers and reduces charge carrier recombination, consequently improving the efficiency of the TDGA-doped device. [ABSTRACT FROM AUTHOR]

To date, although radiation cooling technology has made some progress in numerous aspects, significant challenges remain in terms of efficient cooling and practical applications. Herein, we report the preparation of a polyvinylidene fluoride (PVDF) composite film with a multiscale micro-nano structure, in which zirconia (ZrO2) particles were bonded on the surface of the PVDF fibers via polydimethylsiloxane (PDMS). This PVDF composite film showed a relatively high solar reflectivity (>0.95) and excellent emissivity (>0.96) in the infrared atmospheric window, which resulted in a 21.8 °C and 10.4 °C temperature reduction compared to the simulated skin and ambient temperature under direct sunlight of about 1000 W m−2, respectively. Meanwhile, the combination of the multistage structure and hydrophobicity property of PDMS resulted in superhydrophobicity with a hydrophobic angle of 155° and sliding angle of about 5°, thereby conferring the film with exceptional self-cleaning ability. Notably, PDMS simultaneously facilitated the formation of a bonding structure between the fibers, leading to enhanced mechanical properties. Compared to those of the PVDF electrospun film (F-S), the tensile strength and tensile strain of the designed composite film increased by 9.5 times and 4.4 times, respectively. Thus, the excellent performances of the PVDF composite film provide a great development prospect for the practical application of electrospun films in smart textiles and energy-saving. [ABSTRACT FROM AUTHOR]

Passive cooling is a promising approach for reducing the large energy consumption to achieve carbon neutrality. Foams/aerogels can be considered effective daytime cooling materials due to their good solar scattering and thermal insulation capacity. However, the contradiction between the desired high solar reflectivity and mechanical performance still limits their scalable production and real application. Herein, inspired by the "Floor-Pillar" concept in the building industry, a multi-structure assembly-induced ice templating technology was used to construct all-cellulosic aerogels with well-defined biomimetic structures. By using cellulose nanofibers (CNFs) as pillars and cellulose nanocrystals (CNCs) as floors and methyltrimethoxysilane (MTMS) as a crosslinking material, an all-cellulosic aerogel (NCA) exhibiting high mechanical strength (mechanical strength = 0.3 MPa at 80% compression ratio, Young's modulus = 1 MPa), ultralow thermal conductivity (28 mW m -1 K -1 ), ultrahigh solar reflectance (97.5%), high infrared emissivity (0.93), as well as excellent anti-weather function can be achieved, exceeding the performance of most reported cellulosic aerogels. Furthermore, the mechanisms of the improved mechanical strength and stimulated superior solar reflectance of NCA were studied in detail using finite element simulations and COMSOL Multiphysics. As a result, the NCA can achieve a cooling efficiency of 7.5 °C during the daytime. The building energy stimulus demonstrated that 44% of cooling energy can be saved in China annually if the NCA is applied. This work lays the foundation for the preparation of biomass aerogels for energy-saving applications.

Compared with jagged and rod-like raw products, the spherulitic 3-nitro-1,2,4-triazol-5-one (NTO) crystalline powder is generally superior in the formulation. However, the growth mechanism and corresponding influential factors for NTO spherulites remain to be deeply explored. Herein, the morphological evolutions of NTO crystals in alcohol solvents under a range of maximum supersaturation (Smax) are systematically investigated. It was found that differences in solvent-crystal interface interactions determine the primary morphology of the growing crystals while the magnitude of Smax determines the subsequent polycrystalline evolution. The cooling rate, initial concentration and stirring rate all could affect the crystal morphology by changing the Smax. It is demonstrated that there exists a critical Smax range (1.75–1.88) above which the formation of spherulites is kinetically favorable. Face indexing tests suggest that the (0 0 1) plane of NTO is mostly prone to twinning at low supersaturation, which is because that the molecular layers on the (0 0 1) surface are prone to twisting and the energy difference before and after is only 8.77 kJ mol−1. Then, the interfacial growth theory is employed to explain how a growing crystal plane develops from smooth to rough with non-crystallographic sub-individuals as the crystallization driving force increases. The change of morphology has a positive consequence in improving the safety performance of NTO crystalline powder under drop-weight impact. These findings would forward the understanding of the spherulitic crystallization process for energetic crystals. [ABSTRACT FROM AUTHOR]

We present a workflow that uses digital tools to optimise the experimental approach and maximise the efficiency in achieving the required process parameters for a desired set of crystallisation responses, kinetics and objectives. Model-driven small-scale experiments can contribute to reducing time and material waste in the development of pharmaceutical crystallisation processes. The workflow presented here guides the development of a small-scale batch cooling crystallisation process via solubility measurements, particle shape and size determination, form identification and preliminary kinetic parameter estimation to make crystals that satisfy quality target parameters (for shape, size and solubility) for a given active pharmaceutical ingredient (API). The case study herein follows the development of a crystallisation process for lamivudine, an API used in the preventative treatment of human immunodeficiency virus (HIV). This work identifies ethanol as a suitable solvent, meeting the acceptable solubility parameters for industrially relevant processes and yielded the biorelevant form, form I. The target kinetic parameters that were measured included induction time, growth rate and nucleation rate for lamivudine in ethanol under a range of conditions as guided by experimental planning models. Data was collected as part of the development of a DataFactory platform in which experimental optimisation can be autonomously implemented and all measurements stored in a crystallisation parameter database. This database will have further value in informing model development and continuous crystallisation process design and optimisation. The model objective-driven development workflow identified the following conditions, 19.9 °C, 600 RPM and supersaturation of 1.70, as achieving the desired objective successfully in 80 polythermal and 28 isothermal experiments. Integration of the workflow alongside the optimisation algorithm within the automated DataFactory system will enable fully autonomous, rapid data collection for small-scale API crystallisation. Such autonomous systems could play vital roles in pharmaceutical development and manufacturing driving towards more efficient and sustainable practices via digital transformation. [ABSTRACT FROM AUTHOR]

Reconciling optimal cooling effects with color regulation in functional textiles, while preserving infrared characteristics, remains a formidable technological challenge. Here, a novel dynamically hierarchical metafabric is reported that integrates temperature-adaptive thermochromic and moisture-wicking functionalities into a passive radiative cooling system, which effectively achieves energy-efficient personal thermal management. The objective was achieved by employing a hierarchically organized metafabric, which utilized the techniques of electrospinning and facile spray coating. Specifically, the metafabric is composed of polyamide 6/silicon dioxide/thermochromic chameleon microcapsules/hygroscopic agent layers. The metafabric demonstrates excellent selective infrared emissivity (0.95 in the 8–13 μm wavelength range) and moisture permeability through large-scale electrospinning and hierarchical design, while simultaneously maintaining superior mechanical strength. Specifically, the incorporation of thermochromic microcapsules facilitates reversible color alteration and self-adaptive modulation of solar energy (ΔRlum = 52.64%), which significantly expands the potential applications for energy-saving thermoregulation. The resulting metafabric exhibits exceptional outdoor thermoregulation capabilities, demonstrating a cooling effect of 7.9 °C compared to commercial cotton in an outdoor environment under solar intensity of approximately 40 mW cm−2. This study presents promising potential for the development of advanced personal thermal management systems with exceptional thermoregulatory capabilities, which could have significant implications in various fields such as wearable technology and medical devices. [ABSTRACT FROM AUTHOR]

The radiative cooling of naphthalene dimer cations, (C10H8)2+ was studied experimentally through action spectroscopy using two different electrostatic ion-beam storage rings, DESIREE in Stockholm and Mini-Ring in Lyon. The spectral characteristics of the charge resonance (CR) band were observed to vary significantly with a storage time of up to 30 seconds in DESIREE. In particular, the position of the CR band shifts to the blue, with specific times (inverse of rates) of 0.64 s and 8.0 s in the 0–5 s and 5–30 s storage time ranges, respectively. These long-time scales indicate that the internal energy distribution of the stored ions evolves by vibrational radiative cooling, which is consistent with the absence of fast radiative cooling via recurrent fluorescence for (C10H8)2+. Density functional based tight binding calculations with local excitations and configuration interactions (DFTB-EXCI) were used to simulate the absorption spectrum for ion temperatures between 10 and 500 K. The evolution of the bandwidth and position with temperature is in qualitative agreement with the experimental findings. Furthermore, these calculations yielded linear temperature dependencies for both the shift and the broadening. Combining the relationship between the CR band position and the ion temperature with the results of the statistical model, we demonstrate that the observed blue shift can be used to determine the radiative cooling rate of (C10H8)2+. [ABSTRACT FROM AUTHOR]

This study highlights the occurrence of liquid–liquid phase separation (LLPS) or oiling-out during the crystallization of polymorphic forms of aspirin, which was successfully revealed for the first time through a swift cooling crystallization process from a water–acetonitrile mixed solvent medium. Saturated aspirin solutions with nine different mixing compositions of water–acetonitrile solvents, from pure water to pure acetonitrile, were prepared at 310 K and swiftly cooled down to 274 K. Prior to the experiment, variations in the solubility and pH with different solvent mixture compositions were studied and after the swift cooling of the solutions, variations in the induction time for the occurrence of both LLPS and polymorphic nucleation were evaluated with respect to the various levels of supersaturation generated within the solution. Furthermore, the preferred conditions for the occurrence of LLPS and the polymorphic nucleation were precisely mapped by constructing a phase diagram with the different crystallization parameters involved, which clearly revealed that the nucleation of only form-I of the polymorph occurred in the acetonitrile-rich compositions (≥0.58A) without LLPS and form-II occurred in the water-rich compositions (≥0.92W), mostly in the presence of micro-level LLPS in the solution. Whereas, in the intermediate compositions, LLPS occurred at micro and macro levels between the mixed compositions 0.92W : 0.08A and 0.42W : 0.58A, which completely prevented the nucleation of the aspirin polymorphs. The thermal stability and unit cell structures of the grown polymorphs were confirmed through differential scanning calorimetry, and powder and single-crystal X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Super thermal insulation aerogel materials featuring nano-sized cavities, abundant heterogeneous interfaces, and low dielectric properties offer a promising avenue for the development of materials that excel in both passive cooling and high-frequency terahertz (THz) communication efficiency. In this work, a pre-polymerized vinyl trimethoxy silane (PVTMS) molecule with high cross-linking density was fabricated via radical polymerization, and then polyhedral oligomeric silsesquioxane (POSS) was used for tailoring the cross-linking density and polar functional group ratio of the PVTMS nano-aerogel system, simultaneously. The fabricated aerogels possessed a nanoscale bimodal structure including small (∼30 nm) and large (∼200 nm) pores, where the small pores lead to the nanoscale Knudsen effect and ultra-low thermal conductivity (lower than air), while the large pores induce the Mie scattering effect and enhance solar reflectance for radiation blocking. Thanks to the tailored nanostructure design, the POSS@PVTMS aerogel possessed a high specific surface area (728 m2 g−1), ultra-low thermal conductivity (25.5 mW m−1 K−1), hydrophobic properties (137° water contact angle), high infrared emissivity (averaging ∼99%), and ultra-low dielectric properties (average Dk = 1.13). Hence, the aerogel exhibited an enhanced passive cooling capability (ΔT reached 3.7 °C) along with an impressive THz transmission rate (average 88.7%). [ABSTRACT FROM AUTHOR]

Slowing hot carrier (HC) cooling in lead halide perovskites is important to further improve the efficiency of perovskite solar cells (PSCs). Herein, we found that HC cooling can be efficiently prolonged by incorporating an organic small molecule (TDGA) into the perovskite film as an additive through transient absorption spectroscopy measurements, which is conducive to the extraction of the HC energies by the carrier transport layers and reduces charge carrier recombination, consequently improving the efficiency of the TDGA-doped device.

A relativistic coupled-cluster study of the low-lying electronic states in the radium monohydroxide molecule (RaOH), a radioactive polyatomic molecule of interest to laser cooling and to the search of new physics beyond the Standard Model, is reported. The level positions of the A 2 Π 1/2 and C 2 Σ states have been computed with an accuracy of around 200 cm -1 to facilitate spectroscopic observation of RaOH using laser induced fluorescence spectroscopy, thereby exploiting the systematic convergence of electron-correlation and basis-set effects in relativistic coupled-cluster calculations. The energy level for the B 2 Δ 3/2 state has also been calculated accurately to conclude that the B 2 Δ 3/2 state lies above the A 2 Π 1/2 state. This confirms X 2 Σ ↔ A 2 Π 1/2 as a promising optical cycling transition for laser cooling RaOH.

Radiative cooling materials underperform compared to their theoretical potential due to parasitic heating from contact with ambient air. Solutions to this problem can be expensive or complex to fabricate. Here, a potentially inexpensive, simply fabricated material that improves cooling performance by reducing parasitic heating was created using naturally abundant salts. NaCl and KCl are not typically considered for radiative cooling because of their high hygroscopicity and low mechanical strength; however, these compounds are highly infrared-transparent and can be fabricated into aerogel-like foam structures to provide thermally insulating properties. The salt foams, described herein, scattered (reflected) visible light, transmitted infrared radiation, and provided thermal insulation. They were packaged into mechanical supporting panels to avoid physical disruption and the nanostructure was stabilized to moisture by adding an anti-caking agent. The panels were able to keep an underlying surface below ambient temperature for a full 24 hour cycle and reduced parasitic heating rate by more than half (compared to an uncovered surface). The panels were able to cool a variety of underlying surfaces, even highly absorbing surfaces that are normally well above ambient temperature during the day. This work demonstrates an affordable, easily produced, electricity-free cooling technology with potential to be manufactured for large-scale practical applications.

Thermal management, including heating and cooling, plays an important role in human productive activities and daily life. Nevertheless, in the actual environment, almost all the ambient scenarios come with the challenge that the objects are located in a quite dynamic and variable environment, which includes fluctuations in aspects such as space, time, sunlight, season, and temperature. It is imperative to develop low-energy or even zero-energy thermal-management technologies with renewable and clean energy. In this review, we summarised the latest technological advances and the prospects in this burgeoning field. First, we present the fundamental principles of the daytime passive radiative cooling (PDRC) thermal management device. Next, In the domain of dual-mode systems, they are classified into various types based on the diverse mechanisms of transitioning between cooling and heating states, including electrical responsive, mechanical responsive, temperature responsive, and solution responsive. Furthermore, we conducted an in-depth analysis of the principles and design methodologies associated with these categories, followed by a comparative assessment of their performance in radiative cooling and solar heating applications. Finally, this review presents the challenges and opportunities of dynamic dual mode thermal management, while also identifying future directions., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Zero-field-cooling exchange bias (ZFC EB) has always been a research hotspot for researchers, because it can realize the movement of the magnetization hysteresis loop along the field axis without field cooling, which greatly expands the universality and convenience of the application of the exchange bias effect. Achieving ZFC EB at room temperature is an ongoing challenge. To this end, a design strategy from the sublattice level is proposed, and a wide temperature range ZFC EB up to room temperature with a vertical magnetization shift is observed in the strained kagome antiferromagnet Mn 3.1 Sn 0.9 . Magnetic analysis and first-principles calculations reveal that the ZFC EB arises from the strong exchange interaction between the non-coplanar antiferromagnetic Mn kagome sublattice occupying normal Mn sites and the collinear ferromagnetic Mn sublattice occupying Sn sites. This discovery is of great significance for the application of ZFC EB in antiferromagnetic spintronic devices.

The energy efficiency of buildings has become a critical issue due to their substantial contribution to global energy consumption. Windows, in particular, are often the least efficient component of the building envelope, and conventional smart windows focus solely on regulating solar transmittance while overlooking radiative cooling. Although several recent designs achieved dual-control of solar and radiative cooling, these windows still face limitations in terms of durability, limited modulation ability and energy-saving performance. To address these challenges, we propose a novel dual-control smart window design consisting of a reconfigurable kirigami structure and polydimethylsiloxane-laminated thermochromic hydrogel coated with silver nanowires. In summer, the thermochromic hydrogel turns translucent to suppress the solar heat gain, while the high emissivity kirigami structure covers the exterior surface of the window, promoting radiative cooling. In winter, the hydrogel becomes transparent to allow for solar transmission. Additionally, the kirigami structure undergoes an out-of-plane structural change, opening towards the outside environment to expose the underlying low-emissivity silver nanowires and suppress heat radiation. Our design achieves a promising solar transmittance modulation ability of ∼24% and a good long-wave infrared emissivity regulation ability of 0.5. Furthermore, it exhibits significantly improved durability, which is nine times longer than the lifespan of conventional smart hydrogels. Our novel approach offers a promising solution for constructing energy-efficient and durable smart windows and outperforms existing state-of-the-art solar/radiative cooling dual-regulation smart windows in the literature.

Continuous and homogenous films of spin-coated gadolinium formate provide a solution for efficient local cryogenic magnetic refrigeration. The films possess unprecedentedly high surface cooling power, enough to cool a 325 μm silicon wafer down to sub-K temperatures by a single demagnetization step from 2 K or even liquid He temperatures. [ABSTRACT FROM AUTHOR]

MnCl2·4H2O and Tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) rapidly remove dioxygen (O2) from aqueous solution at a rate of ∼20 mg L−1 min−1 with turnover frequencies (TOFs) of up to 440 000 h−1 in the pH range 7.50–11.0 and at 20–50 °C using hydroxylamine (NH2OH) as reducing substrate. These solutions remain deoxygenated for several hours despite being open to the atmosphere. During this time there is a steady rise in the concentration of in situ generated hydrogen peroxide (H2O2), reaching ∼12 mM after 17 h. The order of selectivity for selected 1st row transition metals was found to be: Mn(II) ≫; Co(II)∼Cu(II)∼Fe(II). No deuterium isotope effect was observed, which suggests that an electron transfer is the rate determining step. A mechanism is proposed that involves two 1-electron transfers from bound NH2OH to bound O2 to produce H2O2 concomitant with two proton transfers from catecholate oxygen atoms. This system can act as an anti-corrosion formulation as the catalytic reduction of O2 results in the removal of O2 from open aqueous solutions and the in situ generated H2O2 can be used as a biocide e.g. to kill L. pneumophila. Batch experiments were carried out to confirm the feasibility of this system to simultaneously inhibit corrosion and also potentially disinfect central heating and cooling water systems. [ABSTRACT FROM AUTHOR]

Humans face a severe shortage of fresh water due to economic growth, climate change, overpopulation, and overutilization. Atmospheric water harvesting (AWH) is a promising solution where clean water is collected from the air through various approaches, including dropwise condensation. However, designing surfaces that balance rapid condensation with efficient water removal is challenging. To address this issue, inspired by the efficient water collection mechanisms in the skin of cold-blooded tree frogs, we propose an eco-friendly approach to collect fresh water from cooled window glass. We fabricated various planar and TiO 2 nanostructured surfaces including surfaces mimicking a lotus leaf and a hybrid surface mimicking a desert beetle and a cactus, with different wettability levels such as superhydrophilic, hydrophilic, hydrophobic, superhydrophobic, and biphilic. Sub-cooling of glass substrates between 5 and 15 °C using a Peltier device significantly enhanced the condensation process for all surfaces, with modest dependency on surface properties. This cooling temperature regime could be achieved by geothermal cooling methods that consume little energy. To improve visibility for window applications, we developed hydrophobic polymer nanofilm-modified glass substrates using a simple spin-coating technique, and achieved comparable water harvesting efficiency to that of nanostructured substrates. Our study provides insight into the optimal surface structures and cooling temperature for window glass AWH systems that could be used with an underground cooling system., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Passive radiative cooling is a promising solution for cooling objects without consuming energy. However, chemical colors absorb visible light and generate heat, posing a challenge in the design of a colored sub-ambient daytime radiative cooler (CSDRC) in a simple and scalable way. Herein, we used nanofibers (NF) to achieve selective spectral absorption of the daytime radiative cooler through a dope-dyeing electrospinning technique. This approach allows for the selective absorption of desired colors in the visible spectrum, while the nanofiber structure provides strong visible and near-infrared light scattering to minimize solar heating. We selected cellulose acetate (CA) with mid-infrared emittance characteristics for efficient sky cooling. Our design enabled the CA NF CSDRC to exhibit an ultra-high NIR reflectance of 99%, a high MIR emittance of 95%, and vibrant colors. These unique optical properties resulted in a reduction of the maximum ambient temperature by 3.2 °C and a cooling power of ≈40 W m -2 at a solar intensity of 700 W m -2 . Additionally, the flexibility and deformability of the colored nanofiber cooler make it suitable for thermal management in various practical applications. Our work provides a simple and scalable solution for designing colored passive radiative cooling materials.