Rapid Evaporation Research Articles

Controllable synthesis of 0D, 1D, and 2D nano lanthanum borates and their dispersion stabilities and tribological properties in rapeseed oil

0D, 1 D and 2 D nano lanthanum borates were prepared by changing the reaction conditions of the hydrothermal method. The effect of reaction time, pH value, temperature, and reactant molar ratio on the shapes and sizes were investigated. The as-obtained nano lanthanum borates were demonstrated by scanning electron microscope (SEM), FT-IR and water contact angle test. The dispersion stability was then evaluated by a spectrophotometry. Moreover, the tribological properties of the prepared 0 D, 1 D and 2 D nano lanthanum borates as lubricating additives in rapeseed oil were investigated on a four-ball tribo-tester. Furthermore, the contact model and underlying lubricating mechanisms were proposed based on the results of surface analysis. The results indicated that nano lanthanum borates with different shapes and sizes could be obtained by regulating the reaction conditions of a hydrothermal method. Ethanol rapid evaporation ultrasonic dispersion method and stearic acid surface modification could improve the dispersion stability of nano lanthanum borates in rapeseed oil. In addition, the as-obtained 0 D, 1 D and 2 D nano lanthanum borates could significantly facilitate the anti-wear and friction-reducing properties of rapeseed oil, especially for 2 D nanoflakes. The enhanced lubricating performance of 2 D lanthanum borate nanoflakes might be attributed to the combined action of relatively lower loads under planar contact forms, thicker and stronger adsorption film generated by plate-like additives, and the enhanced activity of boron atoms and the increased boron-permeation amount on the friction surface to form tribochemical films containing Fe2O3, B2O3 and La2O3.

Tree-inspired efficient solar evaporation and simultaneous in-situ purification of ultra-highly concentrated mixed volatile organic wastewater

The high concentration, complexity and volatility of organic pollutants in actual wastewater are becoming major obstacles to realizing efficient water purification. Inspired by the structure and physiological process of trees, a two-in-one solar-driven evaporation/photocatalysis system for efficient water evaporation and in situ purification was fabricated from wood-derived porous carbon that was vertically aligned and uniformly loaded with polymetallic oxide nanoparticles. The system enabled rapid water evaporation (up to 3.23 kg m-2 h-1) and effective purification of mixed volatile wastewater containing rhodamine B, phenol and tetracycline with ultra-high total concentration of up to 11700 mg L-1 under 1 sun irradiation, which was significantly higher than that reported previously, and distilled water with undetected volatile pollutants could be simultaneously obtained. The combination of nanoparticles and wood hierarchical structures provided photothermal conversion substrates, catalysts and reaction/transmission channels for efficient water evaporation and in situ pollutant degradation and achieved the synergistic promotion of photothermal conversion and photo-Fenton reactions. This process provides a novel and promising strategy for the efficient treatment of highly concentrated mixed volatile organic wastewater.

Herbicide Potential of Selected Essential Oils From Plants of Lamiaceae and Asteraceae Families

Abstract Essential oils from Monarda fistulosa L., Satureja pilosa Vel., Origanum vulgare subsp. hirtum Ietswaart. (Greek oregano), Micromeria dalmatica Benth., Thymus longedentatus (Degen & Urum.) Ronniger, and Artemisa campestris L. were evaluated as inhibitors of seed germination in target plants Lolium perenne L. and Trifolium pratense L. using in vitro assays. The essential oils were applied on the seeds as aqueous solutions at concentrations ranging from 0.5–3.0 µL/mL. Complete inhibition was established at a concentration of 1.5 µL/mL with the most effective essential oils. Oregano oil was evaluated for its inhibitory activity on seed germination under field conditions; the essential oil was applied as an aqueous solution at concentrations of 3, 5, and 10 µL/mL on superabsorbent Terawet. The mass obtained was mixed with the seeds of the target plants and planted in a field. After 1 month, the results were evaluated based on the weight of the aerial parts of the plants from control and experimental areas. At the highest concentration studied, the weight of the plants was 77% lower in the experimental areas than in the controls. The chemical composition of the essential oils was analyzed using gas chromatography–mass spectrometry. The results showed that carvacrol-rich essential oils had a strong inhibitory effect on seed germination. The inclusion of the essential oil on a superabsorbent was a good way to preserve its herbicidal activity under field conditions as this prevented its rapid evaporation.

Study of a Highly Sensitive Formaldehyde Sensor Prepared With a Tungsten Trioxide Thin Film and Gold Nanoparticles

A new gold (Au) nanoparticle (NP)/tungsten trioxide (WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> )-based chemoresistive formaldehyde gas sensor is fabricated and reported. The WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin film and Au NPs are prepared by radio frequency (RF) sputtering and rapid thermal evaporation (RTE) approaches, respectively. The utilized Au NPs successfully elevate the surface area/volume ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{A}/{V}$ </tex-math></inline-formula> ) ratio and improve corresponding sensing performance. Experimentally, the proposed Au NP/WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sensor shows a very high sensing response of 1303.5 and a response (recovery) time of 16 s (16 s) under introduced 20 ppm formaldehyde (HCHO)/air gas at 225 °C. This value is remarkably higher than those of previous reports. In addition, a very low detection content of 40 ppb HCHO/air is obtained, revealing that a widespread detection range of formaldehyde concentration can be acquired for the proposed sensor. To expand the application ability in wireless sensing, a gray algorithm GM(1, 1) model incorporating the first-order differential approach is used to substantially diminish the transmission data, increase the transmission efficiency, and improve the accuracy of the response data. The formaldehyde sensor in this study exhibits advantages including a simple structure, ease of manufacturing, relatively lower cost, practical smart sensing ability, and wireless transmission applications.

Microstructural analysis and characterization of lime mortar of seventeenth century Raigad hill fort from western India

The hill fort of Raigad is a massive historical structure constructed with basaltic stone blocks and cemented together with lime mortar. The lime mortar samples from the fort were examined using a petrological microscope, grain size distribution, X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope coupled with energy dispersive x-ray analysis (SEM–EDX). The mineralogical and compositional characteristic of the mortar was analyzed to provide a compatible repair mix for large scale restoration. Aggregates derived from weathering of basaltic rocks of Sahyadri hills were sourced from the vicinity of the fort. Non-hydraulic aerial lime of moderate porosity was specifically used in India's highly rain-fed Western Ghats for rapid evaporation of water and to prevent the build-up of salts. Thin section analysis and FTIR results indicate the use of organic proteinaceous material during the preparation of lime. FTIR analysis also showed the disorder in the man-made calcite crystals while XRD and SEM–EDX analysis elucidated the mixing of quartz and plagioclase feldspar derived from basaltic aggregates in the calcite matrix. The present study gives a holistic approach to prepare a compatible mortar for restoration.

Electrospray Printing of Polyimide Films Using Passive Material Focusing

In electrospray printing, a high electric potential is used to atomize a liquid solution containing the print material into a spray of charged microdroplets. Rapid solvent evaporation from the drop...

Study on the characteristics of performance, combustion, and emissions for a diesel water emulsion fuel on a combustion visualization engine and a commercial diesel engine

Water-in-oil (W/O) emulsion fuels generate rapid evaporative latent heat owing to the simultaneous vaporization of water particles during the compression (550 °C–700 °C) and combustion processes. Combustion is improved as fuel particulates are emitted during the combustion process. This is due to the reduction in combustion temperature caused by the absorption of this evaporation latent heat and the microexplosions caused by the rapid evaporation of water particulates. This allows the simultaneous reduction of nitrogen oxide and smoke, no requirement of additional devices (unlike pre- and post-treatment technologies), and the use of existing diesel engines without any modification. Therefore, this study applied diesel oil (DO) for automobiles and diesel–water emulsion (DWE) fuel to combustion visualization engines and diesel engines to identify the basic combustion and exhaust characteristics. The results showed that the DWE fuel had a −15.3% reduction in combustion duration compared with DO, which had a −19.6% reduction in nitrogen oxide and a −66.3% reduction in smoke.

Flexible MCNTs cross-linked polyimide membranes with high light absorbance and hierarchical pore distribution for photo-thermal conversion in solar water evaporation

Solar water evaporation membranes are considered as one of the most sustainable and cost-effective strategies to realize seawater desalination, sewage treatment and distillation. However, low-cost preparation of photo-thermal conversion membranes with both high light absorbance and efficient water transport remains a longstanding challenge. Herein, versatile and simple phase inversion strategy combined with surface corrosion is applied to fabricate flexible MCNTs cross-linked polyimide membranes (MCNTs/PIMs) with hierarchical pore distribution. The surface corrosion is used to dissolve the surface dense layer formed during the phase inversion process and obtain the adjustable surface pore structure with high sunlight absorption performance. Besides, the microchannel structure is prepared to realize multiple reflection of incident light and optimize water transport by controlling the coagulating bath. The results demonstrate that the MCNTs/CPIMs exhibit high light absorption performance of 94% in the long wavelength range of 200–2500 nm. The MCNTs/CPIMs possess rapid water evaporation rate of 1.26 kg m−2 h−1 and high solar thermal conversion efficiency of 72.7%. The flexible and scalable MCNTs/CPIMs exhibit efficient light/thermal management and rapid water transport performance, which enables them promising application in sustainable, low-cost and high efficient solar water evaporation.

Formation of Carbohydrate-Metal Adducts from Solvent Mixtures during Electrospray: A Molecular Dynamics and ESI-MS Study.

Electrospray ionization (ESI) is frequently used to produce gas-phase ions for mass spectrometry (MS)-based techniques. The composition of solvents used in ESI-MS is often manipulated to enhance analyte ionization, including for carbohydrates. Moreover, to characterize analyte structures, ESI has been coupled to hydrogen/deuterium exchange, ion mobility, and tandem MS. Therefore, it is important to understand how solvent composition affects the structure of carbohydrates during and after ESI. In this work, we use molecular dynamics to simulate the desolvation of ESI droplets containing a model carbohydrate and observe the formation of carbohydrate adducts with metal ions. Molecular-level details on the effects of formulating mixtures of water, methanol, and acetonitrile to achieve enhanced ionization are presented. We complement our simulations with ESI-MS experiments. We report that when sprayed from aqueous mixtures containing volatile solvents, carbohydrates ionize to form metal-ion adducts rapidly due to rapid solvent evaporation rather than changes in the ionization mechanism. We find that when sprayed from solvent mixtures, carbohydrates are primarily solvated by water due to the migration of more volatile solvents to the surface of the droplet. Ultimately, the structure of the carbohydrate varies depending on its solvent environment, as inter- and intramolecular interactions are affected. We propose that solvents with 25% or more water may be used to enhance the ionization of carbohydrates with minimal effect on the structure during and after ESI.

Temperature- and Solvent-Mediated Confined Assembly of Semicrystalline Chiral Block Copolymers in Evaporative Emulsion Droplets

Self-assembly of chiral block copolymers (BCPs*) not only emerged as a facile strategy to prepare chiral structures but also afforded a key clue to decode and even emulate the vast yet mysterious existence of chirality in nature. Although temperature and solvent properties played a pivotal role in the self-assembly of BCPs* in bulk/films and selective solutions, their impact on BCP* confined assembly is still elusive to date. Herein, we systematically examined the impact of temperature and solvent properties on the 3D confined assembly of polystyrene-block-poly (d-lactide) (PS-b-PDLA) BCPs* in evaporative emulsion droplets. In good solvents for both PS and PDLA, PS-b-PDLA BCPs* featured a kinetically dependent assembly behavior, while enhancing assembly temperature did not show an apparent impact on this trend. It was found that a rapid solvent evaporation was essential to a chiral transfer from PDLA configuration (molecular level) to PDLA microphase separated structure (assembly level) and hence to form chiral particles with an internal helical structure. However, in PS-selective solvents, temperature displayed a considerable impact on particle morphology, with respect to change of the dissolution state of PS-b-PDLA chains and the equilibrium state of assemblies. Moreover, the chirality transfer and the formation of chiral particles were interrupted by the aggregation of PS-b-PDLA chains in selective solvents, but they could be resumed once the aggregates were removed by filtration or employing mixed solvents composed of both good and selective solvents. Accordingly, we highlighted a good dissolution state and rapid assembly kinetics as two prerequisites to the chiral transfer process and the formation of a helical structure under 3D confinement. Our finding enriched the portfolio of assembly scenarios of BCPs* and deepened the understanding on the chiral transfer of BCPs* under 3D confinement.

All‐in‐One Solar Interfacial Evaporation System with Highly Effective Heat Management and Water Collection

Although solar‐driven interfacial water evaporation (SDIWE) exhibits a rapid evaporation rate upon exposure to the open air and solar‐to‐steam conversion efficiency close to 100%, the efficient freshwater collection from a compactly closed SDIWE system remains a big challenge due to the suppressed steam generation on high local humidity near the water evaporation front. Herein, a low‐cost and auto‐floating SDIWE system is capable of transferring the latent heat of condensation (LHC) to the water localized in the photothermal layer without any auxiliary facilities. It allows the limited liquid water to absorb the energy of LHC yet rejects the downward heat conduction from the photothermal layer. As such, the water in the photothermal layer can be preheated significantly, not only reducing humidity but also promoting vapor generation. Compared with the commonly single‐slope evaporator, the clean water productivity of the presented system enhanced by 130% under one sun irradiance. Benefitting from its long‐term stability and superior salt‐rejection function, the presented system shows great potential for sustainable and practical application in freshwater production using natural seawater.

Enhancing the hot-corrosion resistance of atmospheric plasma sprayed Ni-based coatings by adding a deoxidizer

Atmospheric plasma sprayed metallic coatings always contain oxides because of the entrainment of ambient air into plasma jet, which significantly limits their performances and applications. This paper presents an approach to deposit highly dense Ni-based alloy coatings with oxide-free particles achieved by introducing boron as deoxidizer element through plasma spraying to generate ultrahigh temperature Ni20Cr4B droplets. During spraying, boron is preferentially oxidized and the formed B2O3 is completely removed due to rapid evaporation. Thus, the in-flight oxidation of metal can be suppressed to achieve oxide-free particles. The oxygen content of plasma sprayed Ni20Cr4B coating is lower than 0.18 wt.% and presents little change over a wide spray distance range from 60 mm to 140 mm. With such a low oxygen content, the Ni20Cr4B coating presents a highly dense microstructure (porosity of 0.21 ± 0.11%) and well-bonded inter-splat interfaces. The hot-corrosion test at 600 °C for 200 h shows that the highly dense Ni20Cr4B coating can effectively block the penetration of the corrosion media and the corrosion only takes place at the coating surface, while severe inner corrosion was observed for the traditional Ni20Cr coating with poor inter-splat bonding.

New species of fermions and bosons, cosmological constant problem and a farewell to spin–statistics theorem

If dark matter exists in the form of ultralight fermionic and bosonic species, then (a) it can accelerate evaporation of astrophysical black holes to the extent that their lifetimes can be reduced to astronomical time scales, a and (b) if there are extremely large number of such species it has the potential to solve the hierarchy problem [H. Davoudiasl, P. B. Denton and D. A. McGady, Phys. Rev. D 103 (2021) 055014; G. Dvali, Fortschr. Phys. 58 (2010) 528]. Here, we put forward a proposal that darkness of many of these new particles is natural, and in addition, the net zero point energy of the fermions exactly cancels that coming from the new bosons. The needed fermion–boson equality, and matching the fermion–boson degrees of freedom, comes about naturally. A very direct argument that allows the departure from the spin–statistics theorem is presented. a This happens in two steps: first, the relatively rapid evaporation of the ultralight particles, and the second slower one associated with a hundred or so ‘heavier’ particles of the standard model.

One‐Step Synthesis of Hierarchical Structure Polydimethylsiloxane Films with Micro‐/Nanosurfaces for Application in Triboelectric Nanogenerators

Surface optimization of tribomaterial is an effective approach for enhancing the output performance of triboelectric nanogenerators (TENGs). Developing advanced surface structures and their mass fabrication method is the essential technology component of TENG‐based electronics. Herein, a facile, scalable synthesis of hierarchical structure polydimethylsiloxane (HS‐PDMS) films with micro‐/nanosurface morphology and their application in TENGS are demonstrated. The micromorphology of the PDMS surface with random microcraters is achieved using water droplet‐based microtemplates and their rapid evaporation approach. Simultaneously, the nanomorphology on the microcrater surface with nanoripples is automatically formed under the action of surface tension of the PDMS film. The effect of water droplet mass fraction and the rate of heating, which play key roles in the surface morphology and the device's electrical output control, are investigated. This fabrication method of HS‐PDMS is simple and scalable, providing a promising solution of developing tribomaterial for practical TENG‐based electronic devices.

3D-printed hierarchical porous cellulose/alginate/carbon black hydrogel for high-efficiency solar steam generation

Solar steam generation (SSG) has great application prospects in seawater desalination and dye wastewater treatment. However, it is still a challenge to realize a low-cost, rapid evaporation, high water quality and sustainable solar-driven water purification system. Three-dimensional (3D) structural design of evaporator is conducive to promoting evaporation efficiency, which has great potential in SSG field. In this study, 3D hierarchical porous hybrid hydrogel evaporators with embedded carbon black (CB) for SSG are built through 3D printing method. The 3D hierarchically porous cellulose/alginate/carbon black hydrogel (CACH) shows a super-hydrophilic wettability, and excellent light absorption (97%) within the wavelength range from 300 to 2500 nm, which can dramatically improve water transportation capacity and photothermal performance in the evaporator. The evaporation rate of the evaporator is as high as 1.33 kg m-2h−1 and the conversion efficiency of solar energy at 1 kW m−2 (one-sun) solar illumination is up to 90.6%. Moreover, the evaporation also exhibits superior salt resistant performance, and collected water meets World Health Organization (WHO) drinking water standards after purification from seawater. In addition, a small amount of photothermal material (1 wt% CB) is required in this system, which is beneficial to reduce the cost of the system. The 3D-printed hierarchically porous hydrogel evaporator has great application prospects in seawater desalination and wastewater purification.

Numerical modelling of melt droplet interaction with water

A collapse of the vapour film separating a hot melt droplet from the surrounding water due to sudden ambient pressure rise is considered. The pressure peak causes a direct contact between water and melt, leading to significant disturbances of the melt droplet surface. Results of numerical simulations performed by the VOF method are presented. Parametric analysis of the interaction process is performed for a molten tin droplet with initial temperature of 950 K, immersed in subcooled water having the temperature of 353 K. The interaction is initiated by sudden rise of the ambient pressure to as much as 8 MPa, imitating the arrival of a thermal detonation wave, with its gradual decrease towards the initial pressure of 0.1 MPa. Simulations reveal the collapse of the vapour film, impingement of water on the droplet surface, and subsequent expansion of vapour due to rapid water evaporation. Significant disturbances of the melt droplet surface are obtained, and implications for the steam explosion problem are discussed.

Production of 87Rb Bose-Einstein Condensate in an Asymmetric Crossed Optical Dipole TrapSupported by the Key-Area Research and Development Program of Guangdong Province, China (Grant No. 2019B030330001), the National Natural Science Foundation of China (Grant Nos. 12025509 and 11874434), the Science and Technology Program of Guangzhou, China (Grant Nos. 201904020024 and 201804010497), the Natural Science Foundation of Guangdong Province, China (Grant

We report the production of 87Rb Bose–Einstein condensate in an asymmetric crossed optical dipole trap (ACODT) without the need of an additional dimple laser. In our experiment, the ACODT is formed by two laser beams with different radii to achieve efficient capture and rapid evaporation of laser cooled atoms. Compared to the cooling procedure in a magnetic trap, the atoms are firstly laser cooled and then directly loaded into an ACODT without the pre-evaporative cooling process. In order to determine the optimal parameters for evaporation cooling, we optimize the power ratio of the two beams and the evaporation time to maximize the final atom number left in the ACODT. By loading about 6 × 105 laser cooled atoms in the ACODT, we obtain a pure Bose–Einstein condensate with about 1.4 × 104 atoms after 19 s evaporation. Additionally, we demonstrate that the fringe-type noises in optical density distributions can be reduced via principal component analysis, which correspondingly improves the reliability of temperature measurement.

Highly efficient flexible perovskite solar cells with vacuum-assisted low-temperature annealed SnO2 electron transport layer

The demand for lightweight, flexible, and high-performance portable power sources urgently requires high-efficiency and stable flexible solar cells. In the case of perovskite solar cells (PSCs), most of the common electron transport layer (ETL) needs to be annealed for improving the optoelectronic properties, while conventional flexible substrates could barely stand the high temperature. Herein, a vacuum-assisted annealing SnO2 ETL at low temperature (100 °C) is utilized in flexible PSCs and achieved high efficiency of 20.14%. Meanwhile, the open-circuit voltage (Voc) increases from 1.07 V to 1.14 V. The flexible PSCs also show robust bending stability with 86.8% of the initial efficiency is retained after 1000 bending cycles at a bending radius of 5 mm. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements show that the density of oxygen vacancies, the surface roughness of the SnO2 layer, and film hydrophobicity are significantly increased, respectively. These improvements could be due to the oxygen-deficient environment in a vacuum chamber, and the rapid evaporation of solvents. The proposed vacuum-assisted low-temperature annealing method not only improves the efficiency of flexible PSCs but is also compatible and promising in the large-scale commercialization of flexible PSCs.

Unprocessed machining chips as a practical feedstock in directed energy deposition

Directed energy deposition (DED) is an additive manufacturing process capable of creating parts or coatings from powder or wire feedstocks, and may be adapted to use machining chips. Re-use of steel chips as opposed to landfilling or even recycling, has implications for CO2 emission savings. This is particularly the case of like-for-like replacement of powder and other feedstocks. This work addresses two key concerns which currently impede the implementation of chip-based DED – the impact of residual coolant present on chips on part properties, and whether chip type feedstocks can be delivered in a consistent, practical manner similar to powders. The study demonstrates that DED can generate dense, repeatable deposits from 304L stainless steel milling chips, using both pre-placed and vibrationally fed strategies. Milling chips created with and without the use of machining coolant can both be successfully deposited, without compromising the density of the part. EPMA/XRD/EBSD analysis showed no evidence of coolant in deposits, explained by rapid evaporation, and micro-hardness analysis showed it had no effect on hardness. Practical implementation of chip-based feedstocks into DED systems is validated via use of a bespoke vibration feeding system, which is calibrated in this work, and capable of controlled delivery beneath the laser. Melting behaviour under low power is also investigated, revealing chips are readily melted into droplets and incorporate surrounding chips, ultimately yielding efficient material incorporation into tracks.

Highly Efficient and Cost-Effective Water Desalination via the Hybrid Hydrogel-Based Solar-Driven Interfacial Evaporation

The strategy of solar-driven steam generation to collect purified water shows great potential in seawater desalination and domestic wastewater treatment. However, there is still a technical gap in achieving high cost-effectiveness and providing sustainable solutions for rapid evaporation to obtain high-quality and safe water. In this study, a natural rich biomass pectin (Nicandra physalodes (Linn.) Gaertn. polysaccharide) and polypyrrole photo-thermal material were introduced into polyvinyl alcohol network to achieve the construction of a low-cost hybrid hydrogel solar evaporator (total material cost of $7.89 /m2). The mixed evaporator works stably in a long-span acid-base range (pH 1 ~ 14) and salinity range (0 ~ 320 g/kg) with a water purification capacity of 2.42 (kg/m2* h) under 1 sun, and its daily water purification capacity can reach 24.4 kg/m2 under natural light. This paper provides a new possibility for a highly efficient and cost-effective water desalination system with guaranteed water quality.