Water Vapors Research Articles

Long-wave infrared laser-induced breakdown spectroscopy of complex gas molecules in the vicinity of a laser-induced plasma.

Vibration-rotation signatures of intact water and complex organic molecules in vapor phase were detected, identified, and mode-assigned in the long-wave infrared emissions of laser-induced plasma. Time resolved long-wave infrared emissions were also studied to assess the temporal behaviors of these gaseous molecular emitters. The temperatures of these molecular vapors in the hot and transient vapor-plasma plume of the laser-induced plasma were estimated to be well above room temperatures during their existence. The temperatures of the water vapors in the vapor-plasma plume were found to be evolving with time and ranging from>2700K at 10µs to∼1500K at 200µs after plasma initiations using HITRAN/HAPI based molecular spectral analysis. The observations in the present study comprise (to our knowledge) the first direct evidence of hot water and intact complex organic gas molecules in the vicinity of the laser-induced plasma. The findings presented in this work serve as an important step forward in improving the understanding of the thermodynamic characteristics (such as temperatures and phases) of intact complex molecules in a hot and intricate system such as the vapor-plasma plume of a laser-induced plasma, which is essential in both fundamental studies of plasmas and of laser-induced plasma based analytical applications.

Strong and biodegradable films from avocado peel fiber

Plastics are desirable as packaging materials due to their strong, flexible, and low-cost properties. However, their lack of biodegradability is environmentally detrimental. To this end, plant-based natural fiber is a viable option for creating plastic replacing and biodegradable materials. This study aimed to extract lignocellulosic fiber from avocado peel and make films. Acid hydrolysis and alkali treatment were used to obtain the fiber from avocado peel and ZnCl2 to solubilize it and make films by crosslinking the polymer chains through Ca2+ ions. The results reveal that increasing the Ca2+ ions amount significantly reduces moisture content, moisture absorption, water vapor permeability, water solubility, transparency, and elongation at the break of films but improves tensile strength. The films biodegrade within 30 days at the soil moisture content of 22% with a half-life of 3.19–4.63 days. Overall, extract from avocado peel fiber could aid in designing and developing plastic replacement and biodegradable packaging films.

Development of Dry Walnut Shell Edible Film Plasticized with Glycerol and/or Sorbitol and Incorporated with Aloe Vera Gel and Lemon Essential Oil

Edible packaging films produced from biomaterials are environmentally friendly, promising alternatives against synthetic plastics films. The aim of this study was to produce a low-cost edible film from waste dry walnut shell by casting method. Effects of the plasticizer type and concentration, lemon essential oil (LEO) and aloe vera gel (AVG) addition on edible films properties were investigated. Produced edible films characterization analysis were realized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Moisture content, water vapor transmission rate (WVTR), water solubility, swelling index, thicknesses and color parameters of the produced edible films were investigated. Moisture content of the films was decreased between 23.3–50.6% after LEO and AVG addition, except the moisture content of the film plasticized with 20% sorbitol was increased by 518%. WVTR of the films were increased between 8.7–72.3% after LEO and AVG addition due to the hydrophobic character of LEO. Glycerol plasticized edible films water solubility were decreased between 27.3–75.9%, sorbitol plasticized edible films water solubility were increased between 237.5–100.8% with LEO and AVG incorporation. The swelling index of C1 was reduced by 51.5%, C2 was reduced by 62.4%, C4 was reduced by 36.1%. The swelling index of the C3 was increased by 10.5%, C5 was increased by 21.5%. LEO and AVG addition increased to the film thickness maximum 79.2%. Total color changes (ΔE) of glycerol plasticized films were higher than sorbitol plasticized film. The edible film produced can be used in food packaging due to the appropriate physical and barrier properties.

Binary liquid film condensation from water-ammonia vapors mixture flowing downward along a parallel plate condenser

The ammonia-water film condensation is used as an efficient working fluid in industrial applications such as refrigeration, plate condenser and evaporator, absorber/generator heat exchange, air-conditioning, heat pumps and separation processes. The present work focuses on a numerical investigation of water-ammonia condensation on a falling binary liquid film inside a parallel plate condenser by mixed convection. The parallel plate condenser is composed by two parallel vertical plates. One of the plates is wetted by liquidfilm and cooled by the thermal flux cooling while the other plate is isothermal and dry. Parametric computations were performed to investigate the effects of the inlet parameters of gas, the properties of the binary liquid film as well as the thermal flux cooling on the combined mass and heat transfer and on the efficiency of the parallel plate condenser. The results show that an increase in the inlet vapor of ammonia as well as of vapor water enhances the efficiency of the parallel plate condenser. It is shown also that an enhancement of efficiency of the parallel plate condenser has been recorded when the thermal flux cooling and inlet liquid flow rate is elevated. Whereas the increase of the inlet liquid concentration of ammonia inhibits the efficiency of the parallel plate condenser.

Preparation of cost-effective and hydrophobic freshness indicating labels based on passion fruit peel powder and stearic acid

Freshness indicating labels embedded with pH-sensitive anthocyanins are one type of smart packaging technology. However, the application of freshness indicating labels is mainly restricted by the high cost and hydrophilicity of the labels. In order to reduce the manufacturing cost, passion fruit (Passiflora edulis) peel powder rich in dietary fibers and anthocyanins was used to prepare freshness indicating labels in this study. Moreover, the prepared labels were further soaked in 0.01, 0.05 and 0.1 mol/L of stearic acid ethanol solution to increase the hydrophobicity of the labels. Structural characterization results showed the surface of the labels was covered by self-assembled stearic acid crystals. Stearic acid treatment significantly decreased the moisture content (16.90%→10.92%), hydrophilicity (water contact angle of 40.36°→103.01°), water vapor permeability (18.68 × 10−11 g m−1 s−1 Pa−1 → 8.10 × 10−11 g m−1 s−1 Pa−1) and water uptake ability of the labels, which effectively prevented the leak of anthocyanins from the labels. In addition, stearic acid treatment greatly elevated the inner compactness of the films, resulting in improved tensile strength (3.12 MPa→6.18 MPa) and thermal stability. Moreover, stearic acid treatment well maintained the pH-dependent color changeable ability of the labels. The labels changed from reddish brown to olive and brown in the application of shrimp freshness indicating. When the labels were buried in natural soil at 20 °C for 10 days, 82.74%−98.83% of the labels could be degraded. Therefore, this study provides a new and facile way to prepare freshness indicating labels.

Araucaria Araucana thermoplastic starch nanocomposite films reinforced with nanocellulose

Abstract Araucaria Araucana starch is a raw material with proven potential in obtaining biodegradable polymers. Plasticization improves the flexibility characteristics of starch-based films, however, they still tend to have low tensile strength and high hydrophilicity. The addition of nanocellulose is a technique to improve these characteristics. In this paper, the effects of adding different sources and concentrations of nanocellulose (NC) on the properties of thermoplastic Araucaria Araucana films are addressed. One can highlight, the main effects are the increase of tensile strength and transparency of the films along with the reduction of water vapor permeability and water solubility. Further studies involving the reinforcement of Araucaria Araucana starch and nanocellulose should be conducted to overcome the lack of information.

A Deep Potential model for liquid-vapor equilibrium and cavitation rates of water.

Computational studies of liquid water and its phase transition into vapor have traditionally been performed using classical water models. Here, we utilize the Deep Potential methodology-a machine learning approach-to study this ubiquitous phase transition, starting from the phase diagram in the liquid-vapor coexistence regime. The machine learning model is trained on abinitio energies and forces based on the SCAN density functional, which has been previously shown to reproduce solid phases and other properties of water. Here, we compute the surface tension, saturation pressure, and enthalpy of vaporization for a range of temperatures spanning from 300 to 600K and evaluate the Deep Potential model performance against experimental results and the semiempirical TIP4P/2005 classical model. Moreover, by employing the seeding technique, we evaluate the free energy barrier and nucleation rate at negative pressures for the isotherm of 296.4K. We find that the nucleation rates obtained from the Deep Potential model deviate from those computed for the TIP4P/2005 water model due to an underestimation in the surface tension from the Deep Potential model. From analysis of the seeding simulations, we also evaluate the Tolman length for the Deep Potential water model, which is (0.091 ± 0.008) nm at 296.4K. Finally, we identify that water molecules display a preferential orientation in the liquid-vapor interface, in which H atoms tend to point toward the vapor phase to maximize the enthalpic gain of interfacial molecules. We find that this behavior is more pronounced for planar interfaces than for the curved interfaces in bubbles. This work represents the first application of Deep Potential models to the study of liquid-vapor coexistence and water cavitation.

Heterogeneous Ion-Induced Nucleation of Water and Butanol Vapors Studied via Computational Quantum Chemistry beyond Prenucleation and Critical Cluster Sizes.

Water and butanol are used as working fluids in condensation particle counters, and condensation of a single vapor onto an ion can be used as a simple model system for the study of ion-induced nucleation in the atmosphere. Motivated by this, we examine heterogeneous nucleation of water (H2O) and n-butanol (BuOH) vapors onto three positively (Li+, Na+, K+) and three negatively charged (F-, Cl-, Br-) ions using classical nucleation theory and computational quantum chemistry methods. We study phenomena that cannot be captured by Kelvin-Thomson equation for small nucleation ion cores. Our quantum chemistry calculations reveal the molecular mechanism behind ion-induced nucleation for each studied system. Typically, ions become solvated from all sides after several vapor molecules condense onto the ion. However, we show that the clusters of water and large negatively charged ions (Cl- and Br-) thermodynamically prefer the ion being migrated to the cluster surface. Although our methods generally do not show clear sign-preference for ion-water nucleation, we identified positive sign-preference for ion-butanol nucleation caused by the possibility to form stabilizing hydrogen bonds between butanol molecules condensed onto a positively charged ion. These bonds cannot form when butanol condenses onto a negatively charged ion. Therefore, we show that ion charge, its sign, as well as vapor properties have effects on the prenucleation and critical cluster/droplet sizes and also on the molecular mechanism of ion-induced nucleation.

CoP decorated SnS2 nanosheets with synergistic electronic and electrocatalysis sensitization for enhanced room temperature NO2 sensing

Due to the metal-like property and high catalytic activity, CoP material has been regarded as a potential noble metal alternative in gas sensing area. Herein, CoP decorated SnS2 nanosheets were successfully synthesized via an ultrasonic assisted physical combination method. Structure characterizations indicated the ultrasmall sizes and uniform distributions of CoP nanoparticles on SnS2 nanosheet surface. Gas sensing results showed that the SP-3 sensors (mass ratio: CoP/SnS2 =1:3) possessed much higher sensing response (80 %@10 ppm) to NO2 gas at room temperature (RT, 25 °C) than pristine SnS2 (nearly no response) and 5 % Pt modified SnS2 (57.4 %@10 ppm), indicating a better sensitization effect of CoP than Pt nanoparticles. Arrhenius equation fitting results showed that CoP mainly enhanced the NO2 sensing behavior by electronic sensitization via constructing heterojunctions with SnS2. Moreover, the NO2 sensing response of SP-3 sensors also increased with adding trace water molecules, contradict to the response curve versus increasing relative humidity, due to the dynamic equilibrium between electrocatalytic water splitting facilitated surface NO2 adsorptions and over-adsorption of water vapors hindered NO2 adsorptions. This work highlights the important role of CoP in gas sensing, which will also promote the exploration and understanding of novel materials to replace noble metal.

Harnessing plum (Prunus domestica L.) processing wastes for the fabrication of bio-composite edible films: An attempt towards a food circular bioeconomy

This study investigated the effects of different biopolymer matrices on the quality characteristics of edible films produced from plum kernel protein isolate (PKPI), arrowroot starch (ARS), and plum kernel oil (PKO). All eight film-forming matrices produced a self-supporting and peelable film. Among the formulations tested, a composite film containing 50% PKPI, 50% ARS, and 1% PKO (P50S50O) exhibited favourable features, including the highest glass transition temperature and tensile strength, which were 2.05 and 1.59-folds higher than PKPI film, respectively. The composite film (P50S50O) showed a reduced water vapour transmission rate (WVTR), permeance, and water vapour permeability (WVP) indicating a decreased affinity for moisture and an improved tortuosity of the vapour diffusion path. XRD analysis revealed a 55.75% increase in crystallinity, and SEM micrographs showed smoother and more homogeneously entrapped PKO in P50S50O films. Peak shifting in FT-IR spectra confirmed the development of additional cross-linking among various film-forming matrices, which improved the barrier, mechanical, and thermal properties of the composite films, paving the way for the prospective application of plum processing waste in the development of edible films and curbing the environmental pollution of plastics films.

Directional vapor transported and water-proof nanofibrous membranes for liquid desiccant dehumidification systems

The membrane-based liquid desiccant dehumidification system is a newly developed method in the field of air dehumidification. In this study, double-layer nanofibrous membranes (DLNMs) with directional vapor transport and water repellency for liquid dehumidification were fabricated by a simple electrospinning process. Specifically, the combination of thermoplastic polyurethane nanofibrous membrane and polyvinylidene fluoride (PVDF) nanofibrous membrane forms a cone-like structure in DLNMs, resulting in directional vapor transportation. The nanoporous structure and rough surface of PVDF nanofibrous membrane provide waterproof performance for DLNMs. Compare with the commercial membranes, the proposed DLNMs have a significantly higher water vapor permeability coefficient, which is as high as 539.67 g·μm m−2·24 h·Pa. This study not only provides a new route to construct a directional vapor transport and waterproof membrane, but also demonstrates the huge application prospect of the nanofibrous membrane formed by electrospinning in the field of solution dehumidification.

Research on monitoring the transfer of water vapors through textile materials using humidity sensors

The ability of textile materials to transfer water vapor greatly influences the protective and comfort functions of clothing. In order to appreciate the water vapor transfer capacity, standard methods have been defined, but these standardized methods have also some drawbacks. One of these drawbacks is the fact that the environmental conditions for determining the standard characteristics greatly differ from the real operating conditions, which are mostly dynamic. This paper proposes a method for dynamic monitoring of water vapor transfer through multilayer textile assemblies using relative humidity sensors. In addition, the method offers the possibility to determine the water vapor resistance of the textile materials with good accuracy and at a much lower price than using the standard ISO 11092 − 2014. These humidity sensors can be an important component of smart wearable electronic textiles and have potential applications in healthcare in the management of wounds, bed-wetting, and skin pathologies or for microclimate control in clothing for military, firemen, athletes, etc.

Development and Characterization of an Edible Zein/Shellac Composite Film Loaded with Curcumin.

The development of functional edible films is promising for the food industry, and improving the water barrier of edible films has been a research challenge in recent years. In this study, curcumin (Cur) was added to zein (Z) and shellac (S) to prepare an edible composite film with a strong water barrier and antioxidant properties. The addition of curcumin significantly reduced the water vapor permeability (WVP), water solubility (WS), and elongation at break (EB), and it clearly improved the tensile strength (TS), water contact angle (WCA), and optical properties of the composite film. The ZS-Cur films were characterized by SEM, FT-IR, XRD, DSC, and TGA; the results indicated that hydrogen bonds were formed among the curcumin, zein, and shellac, which changed the microstructure and improved the thermal stability of the film. A test of curcumin release behavior showed controlled release of curcumin from the film matrix. ZS-Cur films displayed remarkable pH responsiveness, strong antioxidant properties, and inhibitory effects on E. coli. Therefore, the insoluble active food packaging prepared in this study provides a new strategy for the development of functional edible films and also provides a possibility for the application of edible films to extend the shelf life of fresh food.

Evaluation of two plumes jet plasma reactor for plasmolysis of H2O vapor and CO2 combinations – Optimization study

AbstractA custom design multi‐flying jet plasma torches (MFJPT) reactor was tested for plasmolysis of water vapor and mixtures of water vapor‐carbon dioxide in a series of experimental investigations at various reactor operational parameters. Experimentation plans were applied within the range of induced power (100–300 watts) and various vapor/gas throughputs. The produced gases were analyzed through online gas chromatography. The results of water vapor plasmolysis in two schemes demonstrated the production of 1337 ppm of hydrogen from water vapor/argon and 1665 ppm from applying a water vapor/argon/CO2 combination. Valuable hydrocarbon gases (e.g., Ethane, Ethylene/Acetylene) were generated and detected at higher conversions upon introducing H2O vapor, argon, and CO2 mixtures. The experimental data were trained through machine learning and a Gaussian Process Regression (GPR) model has fitted the data quite well. Ultimately, optimization study outcomes are presented through a color heat‐map for system scaling‐up purposes.

Preparation and characterization of carboxymethyl chitosan/nano-MgO/red cabbage anthocyanins multifunctional films via colloid formation and its application on shrimp preservation

The objective of this study was to evaluate the properties of carboxymethyl chitosan (CMCS)-based nanocomposite films incorporated with nano-MgO and red cabbage anthocyanin (RCA). The MgO content of 0.2% (w/v) resulted in a colloidal film-forming solution with a 60 nm-level diameter. The tensile strength of the consequent film was improved from 7.83 to 25.04 MPa with the film thickness increasing from 63.50 to 85.73 µm, whereas elongation at break decreased from 35.8% to 12.50%. Without affecting the optical transmittance, the incorporation of MgO and RCA significantly enhanced the UV-shielding ability and thermal stability of the CMCS/MgO/RCA films, and significantly decreased their water vapor permeability and water solubility. The SEM result showed that nano-MgO were homogeneously distributed in the CMCS matrix, and the nanocomposite films exhibited improved hydrophobicity with the water contact angle increasing from 45.1° to 76.7°. ATR-FTIR and XRD analyses revealed the molecular interactions in films, including hydrogen bonds, electrostatic attraction, and hydrophobic interaction. Compared to the control, the CMCS/MgO/RCA films exhibited enhanced antioxidant activity and potent antibacterial ability against Escherichia coli and Staphylococcus aureus with the inhibition zone diameter increasing by 67.8% and 50.9%, respectively. Moreover, the addition of RCA made the film color change from red to green within pH 3–12. The obtained films showed great potential in shrimp preservation by suppressing the rise of pH and generation of the total volatile basic nitrogen.

Synergistic effect of nano zinc oxide and tea tree essential oil on the properties of soluble soybean polysaccharide films

Soluble soybean polysaccharide (SSPS)-based composite films with the addition of nano zinc oxide (nZnO, 5 wt% based on SSPS) and tea tree essential oil (TTEO, 10 wt% based on SSPS) were developed by the casting method. The effect of the combination of nZnO and TTEO on the microstructure and physical, mechanical and functional properties of SSPS films was evaluated. The results showed that the SSPS/TTEO/nZnO film exhibited enhanced water vapor barrier properties, thermal stability, water resistance, surface wettability, and total color difference, and almost completely prevented ultraviolet light transmission. The addition of TTEO and nZnO had no significant effect on the tensile strength and elongation at break of the films, but decreased the percentage of light transmittance of the films at 600 nm from 85.5 % to 10.1 %. The DPPH radical scavenging activity of the films significantly increased from 46.8 % (SSPS) to 67.7 % (SSPS/TTEO/nZnO) due to the presence of TTEO. Scanning electron microscopy analysis indicated that nZnO and TTEO were evenly dispersed in the SSPS matrix. The synergistic effect of nZnO and TTEO endowed the SSPS film with excellent antibacterial activity against E. coli and S. aureus, suggesting that the SSPS/TTEO/nZnO film could be a promising material for active packaging applications.

Hamilton's principle with phase changes and conservation principles for moist potential vorticity

AbstractMany definitions of moist potential vorticity (PV) have been proposed to extend the dry theory of Ertel PV. None of the moist PV definitions seem to have all of the desirable properties of the dry Ertel PV. For instance, dry PV is not only a globally conserved quantity, but also a material invariant that is conserved along fluid parcel trajectories. Therefore, an open question remains: Is there a moist PV that is a material invariant, if clouds and phase changes of water are present? In prior studies, definitions of moist PV have been proposed based on physical and mathematical intuition. Here, a systematic approach is used. In particular, a particle relabeling symmetry is devised for a moist atmosphere and then Noether's theorem is employed to arrive at the associated conservation laws for a moist PV. A priori, it is not clear whether this systematic approach will be viable, since it relies on variational derivatives in Hamilton's principle, and phase changes introduce singularities that could potentially prevent derivatives at the cloud edge. However, it is shown that the energy and the Lagrangian density are sufficiently smooth to allow variational derivatives, in a moist Boussinesq system with reversible phase transitions between water vapor and liquid cloud water. From the particle relabeling symmetry, a moist Kelvin circulation theorem is found, along with a moist PV conservation law that applies not for each individual parcel but for parcel‐integrated PV, integrated over certain local volumes.

Multiphase flow characteristics and gas loss in the shear layer on a ventilated supercavity wall

The shear flow on the large-scale gas–water wall inside a ventilated supercavity exhibits gas entrainment mode and determines the change law of the supercavity's gas loss, significantly impacting the shape and dynamics of the supercavity. Therefore, to develop an accurate prediction model and a ventilation control method for a supercavity under complex motion conditions, it is required to systematically and quantitatively study the shear flow characteristics and rules. This study calculates and comparatively analyzes the shear layers on either side of the supercavity wall based on numerical simulations of ventilated supercavitating flows in an unbounded field using the gas–vapor–water multi-fluid model. It is shown that the external shear layer with a very irregular outer boundary is considerably thinner than the internal shear layer. We further analyze the flow and distribution characteristics of all the phases in the shear layers with and without the influence of gravity. Our analysis confirms that all the phases exhibit a similar velocity change rule along the supercavity radial direction in the shear layer, whereas gas and water phases exhibit opposite radial phase distribution trends. It was also seen when natural cavitation occurs that the vapor phase is mainly distributed in the head of the supercavity. Moreover, at the same radial position, it was seen that the vapor velocity was higher than the gas velocity and slightly lower than the water velocity. Using the shear flow and phase distribution characteristics, a shear-layer gas loss model is established and validated for ventilated supercavitating flows.

Remote Operation of an Open-Path, Laser-Based Instrument for Atmospheric CO2 and CH4 Monitoring

The technical specifications and the evaluation of the remote operation of the open-path, tunable diode laser absorption spectroscopic (TDLAS) instrument are presented. The instrument is equipped with two low optical power diode lasers in the near-infrared spectral range for the atmospheric detection of carbon dioxide, methane, and water vapors (CO2, CH4, and H2O). Additionally, the instrument eliminates the requirement of retroreflectors since it detects the back reflection of the laser beam from any topographic target. The instrument was operated remotely by measuring background concentrations of CO2 and CH4 in the atmosphere from 24 November 2022 to 4 January 2023. The accuracy of CO2 and CH4 measurement retrievals on a 200 m laser path was estimated at 20 ppm (4.8%) and 60 ppb (3.1%), respectively. The CH4 accuracy is comparable, but the CO2 accuracy is noticeably lower than the accuracy achieved in local operation. The accuracy issues raised are studied and discussed in terms of the laser driver’s cooling performance.

EVA/zinc oxide nanocomposites for active food packaging: selected physical, and microbial properties

The melt-mixing method was used to obtain nanocomposites of ethylene vinyl acetate copolymer (EVA) with 1, 3 or 5wt% of hydrophilic zinc oxide (ZnO) nanoparticles. The contact angle, barrier and antimicrobial properties of the obtained composites were investigated. The nanocomposites were characterized by better hydrophilic and barrier properties, as evidenced by, respectively, a smaller contact angle and lower water vapor permeability and water absorption compared to EVA, which can be explained by the formation of hydrogen bonds between EVA and ZnO. In addition, the composites were characterized by greater bactericidal activity against E. coli and S. aureus. The optimal physical and microbial properties were obtained with 3 wt% ZnO content.