Saturated Vapor Pressure Research Articles

Environmental response characteristics of the carbon and water fluxes above complex urban surfaces of a subtropical megacity in China

Carbon-water cycle represents a fundamental material cycle within urban ecosystems, characterized by interdependence and inseparability. Based on flux measurements in Shenzhen, we analyzed periodical dynamics of carbon and water fluxes and simulated their variations using four machine learning models. The results indicated that hourly carbon fluxes exhibited a typical U-shaped trend, while water fluxes showed an inverse trend. Seasonal carbon sink capacity was strongest in spring and winter and lowest in summer. Human activities influenced carbon and water fluxes, evidenced by shorter duration of carbon sequestration at suburban station (10 h) compared to exurban station (10.5 h). Seasonal mean carbon fluxes ranged from −5.285 to −2.514 μmol m−2∙s−1 at exurban station and from −2.197 to −1.352 μmol m−2∙s−1 at suburban station, while seasonal mean water fluxes of the above stations ranged from −3.454 to −1.136 μmol m−2∙s−1 and from −1.436 to −0.322 μmol m−2∙s−1, respectively. Exurban station demonstrated a greater carbon sequestration capacity and a higher transpiration intensity than suburban station. The environmental factors influencing carbon and water fluxes of the two stations were generally similar and with some differences. At the exurban station, there was a weak negative correlation between photo-synthetic active radiation and carbon flux, whereas at the suburban station, it was weakly positively correlated. Carbon fluxes at both stations displayed a positive correlation with temperature and relative humidity, while exhibiting a significant negative correlation with saturation vapor pressure deficit. The comparative studies are important for revealing the regularities, influencing factors, and mechanisms of carbon and water cycling in subtropical urban ecosystems.

Machine Learning Model to Predict Saturation Vapor Pressures of Atmospheric Aerosol Constituents

Machine Learning Model to Predict Saturation Vapor Pressures of Atmospheric Aerosol Constituents

Highly efficient regeneration of VOCs-saturated activated carbon by vacuum-thermal treatment

The substantial energy consumption and carbon loss associated with conventional thermal regeneration of activated carbon (AC) pose significant constraints on the advancement of deactivated AC recycling. Here, a vacuum-thermal process was applied to regenerate AC saturated with VOCs. Results showed that desorption efficiency under vacuum conditions (99 % at 200 °C) was significantly higher than that in air and nitrogen (85.2 % and 86.4 %, respectively). The adsorption capacities of different AC samples were maintained at 74.2 %, 97.8 %, 90.9 %, and 96.4 % after seven regeneration cycles, respectively. Pore structure analysis showed that vacuum-thermal regeneration caused less damage to the AC pore structure compared to the air and nitrogen. In addition, micropores were shown to be most conducive to the adsorption of VOCs, while mesopores larger than 4 nm are conducive to desorption. The larger the saturated vapor pressure of the VOCs, the larger the driving force it is subjected to, and the easier it is to desorption. Density field theory (DFT) calculations showed that the higher the binding energy between VOCs and AC surface, the more stable the adsorption system, making it more difficult to regenerate the adsorbent. This work provides insight into the development of an economical and environmentally friendly regeneration route for AC adsorption.

Fabrication of three-dimensional bicontinuous porous aluminum by vapor phase dealloying

The development of lightweight, high-specific-surface-area, and exceptionally tough porous aluminum (Al) through dealloying has been consistently captured the attention of the porous metal field. However, widely employed dealloying approaches such as electrochemical dealloying (ECD) and liquid metal dealloying (LMD) face limitations in constructing porous metals with high chemical reactivities. In this study, we employed an emerging vapor phase dealloying (VPD) method, utilizing the differences in saturated vapor pressures among alloy constituents to selectively remove elements with high vapor pressures under optimized temperature and vacuum conditions. The VPD process, characterized by its chemical-free nature and the application of high temperatures, rapidly produces porous Al with varying ligament sizes from the MgZnAl system. The resulting porous Al, distinguished by its crack-free structure and substantial ligament size, exhibits remarkable toughness. The successful fabrication of porous Al using the VPD method effectively bridges the existing gap in generating porous metals with low melting points and high chemical reactivity through ECD and LMD methods. This advancement holds significance for broadening the range of systems and application fields for porous metals.

Determination of Various Physical–Chemical Properties of bis(2-Methylbutyl) Itaconate and bis(3-Methylbutyl) Itaconate from Bio-Based Resources

Alternative sources for an industrial production of essential substances represent an exciting field of study for many researchers. Based on the previous research, itaconic acid and its esters were intensively studied as one of the sources. This paper relates to a determination of the basic physical–chemical properties of bis(2-methylbutyl) itaconate and bis(3-methylbutyl) itaconate that are produced from itaconic acid and 2-methylbutan-1-ol and 3-methylbutan-1-ol, respectively, from biomass. According to our best knowledge, physical–chemical properties of these substances, such as density, viscosity, and saturated vapor pressure, are not presented in the literature, and these are important for the future research of their production.

Effect of Hydrophobic Dust Particles on the Evaporation Rate from Water Surface

In the paper, the effect of natural dust deposited from the air on the evaporation rate from the water surface is experimentally investigated. Experiments were conducted for stationary liquid without wind blowing across the surface and with mild wind that does not deform the surface, at a constant rate of particle deposition. It is shown that the evaporation rate is a linear function of the difference in the saturated vapor pressure at the water surface and the partial pressure of the air mixture at the temperature and relative humidity in the laboratory at the beginning of the deposition process, when the proportion of the surface covered with dust is small. With the increase in deposition time, hydrophobic particles gather into conglomerates, reducing the proportion of the exposed surface and the evaporation rate.

Vapor pressure of tetrasubstituted metal phthalocyanines bearing fluorine substituents in non-peripheral positions

In this paper, the temperature dependence of the saturated vapor pressure of fluorosubstituted phthalocyanines with substituents in non-peripheral positions of the macroring, viz. MPcF4-np, M=Cu, Fe, Co, VO, was investigated by the Knudsen effusion method with mass spectrometric registration of the gaseous phase composition. The standard thermodynamic parameters [Formula: see text]°[Formula: see text] and [Formula: see text]°[Formula: see text] of the sublimation process of these compounds were determined. The results were compared with the vapor pressure of the corresponding MPcF4-p analogs bearing F-substituents in the peripheral positions. It was shown that the volatility decreased in the order of VOPcF4-np > CoPcF4-np ∼ CuPcF4-np ∼ FePcF4-np > ZnPcF4-np, which correlated with the increase in their crystal lattice energy in the same order. The volatility of most MPcF4-np (M = Cu, Zn, Co, VO) was lower than that of MPcF4-p. The results were analyzed from the point of view of crystal packing and intermolecular interactions in the crystal.

Study on the variation characteristics and influencing factors of stem water content of Acer truncatum during the overwintering period.

Stem water content serves as a pivotal parameter that reflects the plant vitality and maintains their internal water balance. Given the insufficient comprehension regarding the stem water content characteristics and its influencing factors during different stages of the overwintering period, the study focused on Acer truncatum Bunge and developed an Internet of Things (IoT)-based ecological information monitoring system. The system incorporated a proprietary stem water content sensor, allowing non-invasive, in-situ and real time acquisition of stem water content while monitoring diverse environmental parameters. We conducted a detailed elucidation of stem water content variation characteristics and their responses to diverse environmental factors. The results showed: (1) During the overwintering period, stem water content exhibited diurnal variations characterized by " daytime ascent and nighttime descent" across the three stages, exhibiting differences in the moment when the stem water content reaches extremal values and daily fluctuations ranges. Stem water content exhibited minimal fluctuations during deciduous and bud-breaking stages but experienced significant freezing-thawing alternations during the dormant stage, leading to an increased daily fluctuation range. (2) The Pearson correlation coefficients between environmental parameters and stem water content varied dynamically across stages. Path analysis revealed that during the deciduous stage, stem temperature and saturation vapor pressure deficit were dominant factors influencing stem water content; during dormant stage, air temperature and saturation vapor pressure deficit directly impacted stem water content; during the bud-breaking stage, the primary parameters affecting stem water content were saturation vapor pressure deficit and stem temperature. The study provides valuable insights into unveiling the water transport patterns within tree stems tissue and their environmental adaptation mechanisms during the overwintering period, aiding in the scientific development of winter management strategies to protect trees from severe cold and freezing damage, while fostering healthy growth in the subsequent year.

PRESSURE САLCULATION OF THE FIRST DIFFERENTIAL SEPARATION STAGE OF GAS FROM RESERVOIR OIL

The multistage separation of associated gas from reservoir oil is based on a gradual decrease in pressure and sequential selection of light components into the gas pipeline. The final tasks of the separation process are: the pressure at the first stage and the quality of commercial oil according to the pressure of saturated oil vapor. The separation of phases of borehole products is performed by material balance method, first in molar terms, then in mass terms. The thermobaric conditions for the oil and gas separation stages are selected based on the production need for heating the oil-water emulsion and stabilizing the oil at the final stage of the technological process of the final product treatment.The article considers the features of differential separation, proposes a method for express pressure evaluation at the first separation stage and reveals a linear relationship between this parameter and the methane content in reservoir oil for a sample of 41 oil production facilities. The issues of assessing of degassed oil stability after multistage separation are considered.

Developing a durable anti-frost surface: Integrating the passive anti-icing properties of salt, saline, and bulk ice for enhanced frost prevention

Icing on surfaces presents significant challenges for the aviation industry and life in cold alpine regions. Developing smart surfaces to mitigate icing effects is highly desirable. When icing cannot be completely avoided in the atmosphere, limiting it to a small area on the surface is a practical solution. We have created a hydrophilic pattern on superhydrophobic surfaces using laser fabrication, which allows saline droplets to adhere to the pattern. As these droplets dry, salt grains cover the pattern, making the surface primarily superhydrophobic. Under frost conditions, the salt grains turn into saline beads, which then freeze into ice beads. Frost forms only on the tops of these ice beads within the pattern. Due to the lower saturated vapor pressure of salt, saline, and ice compared to the supersaturated vapor pressure for condensation, there is not enough humidity around the pattern for water vapor to condense and form frost. As a result, water vapor continuously deposits inside the pattern, significantly reducing frost formation around it. This combination of salt, saline, and ice, with their lower saturation vapor pressures below zero Celsius, ensures a dry perimeter during rapid temperature drops and increased humidity. By designing the pattern size appropriately, the dry perimeters overlap, keeping the entire surface outside the pattern free of frost. This approach offers a promising solution for reducing frosting on surfaces.

Promising Catalyst for Chlorosilane Dismutation

Currently, the most common method of silane synthesis for electronics and photovoltaics is trichlorosilane dismutation. Therefore, an experimental study of the kinetics of the dismutation reaction of chlorosilanes is of scientific and practical interest. A catalyst has been proposed that allows the dismutation reaction to be carried out in a wide range of temperatures and pressures. Both kinetic and thermodynamic data on the dependence of the rate of the dismutation reactions of trichlorosilane, dichlorosilane, and monochlorosilane on pressure were experimentally obtained. In addition, the dependence of saturated vapor pressure on temperature for monochlorosilane and dichlorosilane were also experimentally determined. Using the example of TCS, it was experimentally established that increasing the pressure to six atmospheres makes it possible to increase the specific productivity of the reactor by at least an order of magnitude due to the acceleration of the chemical reaction and the increase in the molar concentration of chlorosilanes in the vapor mixture. Consequently, it becomes possible to multiply the reactor’s load on the substance and, accordingly, the performance of the chlorosilane dismutation apparatus in general.

Efficient separation and recovery of neodymium through volatilization in the recycling process of spent Nd-Fe-B magnets

Metal Pb can be used to selectively extract Nd from Nd-Fe-B magnet scraps. However, the separation of Nd from the recycled Pb–Nd alloys has become a new problem. In this work, the separation of Pb from the Pb–Nd alloys by vacuum distillation was investigated. The thermodynamic analysis based on the saturation vapor pressure and separation coefficient indicates that the component Pb is able to be separated from the Pb–Nd alloys by vacuum distillation. The effects of the distillation temperature and duration on the volatilization separation of Pb from the Pb–Nd alloy have been clarified, and the dynamic mechanism of the distillation separation was analyzed. The results show that the increase in the distillation temperature and duration can facilitate the separation between the components Pb and Nd in the Pb–Nd alloys. When the Pb-30 wt%Nd alloy was distilled at 1573 K and 0.1–5 Pa for 210 min, the removal rate of the Pb can reach more than 99.99 %, and the Nd content of the distillation residue was determined to be more than 99.41 wt%. This work provides a new and clean route for the separation and recycling of the rare earth metal Nd in the recycling process of spent Nd-Fe-B magnets.

Thermochemical and physical characteristics of isomeric tetracycloundecanes obtained from endo- and exo-dicyclopentadienes

By combining the cyclopropanation and hydrogenation processes of endo- and exo-isomers of dicyclopentadiene, two pairs of tetracycloundecane stereoisomers were obtained, differing in the position of a three-membered cycle. For the first time, under the same conditions for the exo,endo- and exo,exo-tetracyclo[5.3.1.02,6.08,10]undecanes and endo,anti- and exo,anti-tetracyclo[6.2.1.02,7.03,5]undecanes obtained the enthalpy of combustion and formation, saturated vapor pressure and enthalpy and entropy of vaporization were determined, and critical temperatures, pressures, volumes, Pitzer's acentric factors and critical compressibility factors were calculated. The isomers obtained have a higher energy density than JP-10.

Adapted thermodynamical model for the prediction of adsorption in nanoporous materials

In this paper, we introduce a novel, adapted approach for computing gas adsorption properties in porous materials. Our methodology is based on the Dubinin-Polanyi’s adsorption model, and we investigate various frameworks to estimate its required essential components and prediction capabilities. The required components are linked to the physicochemical properties of the adsorbates, such as the vapor saturation pressure and density in the adsorbed phase. To conduct this analysis, we obtain adsorption isotherms for several metal–organic frameworks encompassing a range of pore sizes, shapes, and chemical compositions. We then apply and evaluate multiple combinations of models for saturation pressure and density. After the evaluation of the methods, we propose a working thermodynamic model for computing adsorption isotherms, which entails using the critical isochore as an approximation of the saturation pressure above the critical point and applying Hauer’s method with a universal thermal expansion coefficient for density in the adsorbed state. This framework is applicable not only to simulated isotherms but also to experimental data from the literature for various molecules and structures of different natures, demonstrating robust predictive capabilities and high transferability. Our method showcases superior performance in terms of accuracy, generalizability, and simplicity compared to existing methods currently in use. In light of our results, this method, starting from a single adsorption curve and based on physically interpretable parameters, can predict adsorption properties across a wide range of operating conditions.

The fate of an inhaled cigarette puff in the human respiratory tract

Objective Cigarette smoking can lead to a host of adverse health effects such as lung and heart disease. Increased lung cancer risk is associated with inhalation of carcinogens present in a puff of smoke. These carcinogenic compounds deposit in the lung at different sites and trigger a cascade of events leading to adverse outcomes. Understanding the site-specific deposition of various smoke constituents will inform the study of respiratory diseases from cigarette smoking. We previously developed a deposition model for inhalation of aerosol from electronic nicotine delivery systems. In this study, the model was modified to simulate inhalation of cigarette smoke consisting of soluble and insoluble tar, nicotine, and cigarette-specific constituents that are known or possible human carcinogens. Materials and Methods The deposition model was further modified to account for nicotine protonation and other cigarette-specific physics-based mechanisms that affect smoke deposition. Model predictions showed a total respiratory tract uptake in the lung for formaldehyde (99%), nicotine (80%), and benzo[a]pyrene (60%). Results The site of deposition and uptake depended primarily on the constituent’s saturation vapor pressure. High vapor pressure constituents such as formaldehyde were preferentially absorbed in the oral cavity and proximal lung regions, while low vapor pressure constituents such as benzo[a]pyrene were deposited in the deep lung regions. Model predictions of exhaled droplet size, droplet retention, nicotine retention, and uptake of aldehydes compared favorably with experimental data. Conclusion The deposition model can be integrated into exposure assessments and other studies that evaluate potential adverse health effects from cigarette smoking.

Mechanics and thermal analyses of microfluidic nerve-cooler system

Recent advances in microelectronics and biomedical technology has led to capabilities for integrating programmable cooling mechanisms into bioelectronic devices for pain management and other important applications in human health. However, achieving localized and precise targeted cooling remains a challenge due to the influence of tissue mechanics during device placement/operation, viscous effects in the flow of coolants, and critical physical parameters that locally affect tissue temperature and mechanical responses. Recent studies demonstrate that bioelectronic devices can be equipped with microfluidic structures designed to support phase-change cooling mechanisms, with cooling power adjustable by control of fluid flow rates. When operated in closed-loop feedback schemes based on measurements of temperature at the tissue interface, these platforms can achieve precise temperature control of regions of peripheral nerves involved in pain signaling. Establishing a theoretical model to understand the effects of these devices on the underlying soft and deformable tissues, along with microfluidic deformations that can alter the heat transfer cooling process in viscous flow, is critical for optimized design and operation. To address this, a theoretical model is developed to describe the influence of remote strain in the tissue and to quantify the spatial temperature distribution of tissue cooled by fluid phase change in deformable microfluidic channels. A scaling law is derived to quantify the steady-state temperature distribution in the tissue under physiologically relevant mechanical loads, fluid viscosity, flow rates, and thermal conductivities, enabling the prediction of liquid and gas flux based on expected temperature changes and saturated vapor pressure in the deformed tissue and microchannel. These findings reveal that within a reasonable physiological range, the influence of fluid viscosity on temperature changes can be neglected, and the ratio of fluid to tissue thermal conductivity minimally impacts the temperature change at relatively high flow rates. Additionally, the model suggests a limit to tissue cooling for a given fluid, which may not necessarily increase with higher fluid volumes.

Ultra-wide temperature range aqueous electrolyte through local aggregation anchoring active water towards practical aqueous zinc metal battery

The key to realizing the application of aqueous electrolytes to extreme environments lies in rational constraints on active water. Herein, a strategy for local aggregation electrolyte (LA-Zn(OTf)2) with dynamic anchoring of active H2O is proposed and achieved by precisely regulating the molecular weight and addition amount of organic long chains enriched with hydrogen-bond acceptors. The results show that the saturated vapor pressure of LA-Zn(OTf)2 is reduced by 16 % at 90 °C and it does not freeze at -30 °C, achieving a wide operating temperature range of 120 °C. In LA-Zn(OTf)2, the local aggregation of Zn2+, solvent water, and ether bonding groups form a contact ion pair (CIP) structure, which enables rapid and stable deposition of Zn metal. Moreover, a stable organic-inorganic solid electrolyte interface (SEI) is formed to suppress corrosion and hydrogen evolution. At room temperature, the Zn|LA-Zn(OTf)2|Zn symmetric cell is stably cycled for over 4000 h at 1 mA cm-2. At the extreme temperatures of 90 and -30 °C, the Zn|LA-Zn(OTf)2|NVO full cells achieve stable cycling more than 1400 and 2000 cycles at 0.5 A g-1, respectively, and the capacity retention rates are 70.1 % and 80.5 %, respectively.

Saturated Vapor Pressure and Thermochemical Properties of l- and dl-Threonine

Saturated Vapor Pressure and Thermochemical Properties of <scp>l</scp>- and <scp>dl</scp>-Threonine

Study on Mn Volatilization Behavior During Vacuum Melting of High-manganese Steel

As an alloying element in steel, manganese can considerably enhance the mechanical properties of structural steel. However, the Mn volatilisation loss in vacuum melting is severe because of the high saturated vapour pressure, resulting in an unstable Mn yield and Mn content fluctuation. Therefore, a systematic study of the volatilisation behaviour of Mn in vacuum melting is required to obtain a suitable Mn control process to achieve precise control of Mn composition, thereby providing a theoretical basis for industrial melting of high-Mn steel. In order to explore the Mn volatilization behavior, the volatilization thermodynamics and volatilisation rate of Mn, as well as the influence factors are discussed in this study. The results shows that Mn is extremely volatilised into the vapour phase under vacuum, the equilibrium partial pressure is closely related to Mn content and temperature. With an increase in the Mn content, a higher C content has a more obvious inhibitory effect on the equilibrium partial pressure of Mn. The maximum theoretical volatilisation rate of Mn shows a linear upward trend with an increase in Mn content. However, a higher C content has a more obvious effect on the reduction of the maximum theoretical volatilisation rate with the increase of Mn content. This study provides an improved understanding of Mn volatilisation behaviour as well as a theoretical foundation for consistent Mn yield control during the vacuum melting process of high-Mn steel.

Separation behavior of metal and oxide: Vacuum gasification for metal recovery advanced from lead anode slime

Lead anode slime (LAS), a significant secondary resource, was utilized to separate andrecycle of rare and precious metals such as Te, Au, and Ag, along with essential metals Cu, Pb, and Bi. The conventional pyrometallurgical and hydrometallurgical processes generated hazardous waste, including high levels of As, Sb, smoke, heavy metal waste. Extraction of these key metals is both laborious and ineffective. A novel vacuum gasification technology was employed to explore the separation patterns and migration distribution principles of metal and oxide (MO) in LAS. The theoretical results of phase transition enthalpy change (ΔH), saturated vapor pressure, and molecular average free path investigated the gasification and volatilization potential of MO in LAS. Furthermore, the experimental results revealed separation behavior of MO. As and Sb were evaporated into the gaseous phase to facilitate their separation from other substances at 773 K. Pb and Bi behavior were similar to them at 823 K, As, Sb, Pb and Bi to enter the gaseous phase for the purpose of separation with Ag, Au, and Cu. By exploiting the differences of gasification specificity, it is possible to separate Ag, Au, Cu, and other elements at 1173 K, finally leading to the formation of Ag–Au–Cu alloys.