Evaporation Stage Research Articles

Comparative organic pollutants removal efficiency and life cycle assessment of pyrolysis and solvent elution for industrial waste salt recycling.

Managing industrial waste salt plays a vital role in environmental protection and resource utilization, with a focus on effective removal of organic pollutants and comprehensive life cycle assessment. This study focuses on waste salt produced by the pharmaceutical, pesticide, fluorochemical, and dyeing industries, assessing the efficiency of pyrolysis and solvent elution techniques in removing organic pollutants. Additionally, a life cycle assessment (LCA) was conducted to assess the environmental impacts associated with the two technologies. The findings reveal that pyrolysis significantly enhances the removal of organic pollutants, offering an average improvement of 19.37% over the solvent elution method. This improvement is particularly notable in the treatment of waste salt from agricultural and textile industries, where removal rates exceed 90%. Moreover, ammonium-based waste salts produced by the dyeing industry, due to their lower thermal stability and reduced pyrolysis yield, are more suitable for solvent elution. The LCA indicates that pyrolysis results in less overall environmental risk compared to the solvent elution process. In terms of carbon emission potential, pyrolysis technology emits less carbon dioxide equivalent (CO2 eq.), with a total of 1144kg CO2 eq. emitted when processing one ton of waste salt. The environmental impact of pyrolysis is primarily attributed to the energy consumption during the pyrolysis and evaporation stages. In contrast, the environmental impacts of solvent elution are mainly related to the use of toxic eluents and the high energy consumption of the subsequent distillation to recover the solvent.

K, Sr isotopes, and trace element to constrain potash origin in the Simao Basin, southwestern China, and insight into K isotope geochemical behavior in evaporite

With the advancement of emerging potassium isotope testing techniques, the characteristics of δ41K in evaporite have garnered increasing attention. Its application in constraining the genesis of potash deposits and tracing the process of potash mineralization holds significant prospects. A comprehensive analysis of the geochemical characteristics of K, Sr isotopes, and trace elements provides an opportunity to address the ongoing debate regarding the mineralization mechanism of potash in the Simao Basin. In this study, we collected 64 potash samples from the Simao and Khorat basins. The analytical results revealed that the major ions in the samples consist of Na+, K+, Mg2+, Ca2+, Cl−, and SO2- 4, while the trace elements Br, Sr, Rb, B, Li, V, Cr, Mn, Ba, As, and Zn are relatively enriched. The δ41K values range from − 0.12 ‰ to 0.20 ‰ with an average of 0.01 ‰. The 87Sr/86Sr ratios range from 0.707553 to 0.708565 with an average of 0.708020, which is lower than that of the river water in the drainage basin. Additionally, the Br content ranges from 316.3 × 10−6 to 1709.1 × 10−6, with an average of 633.8 × 10−6. These data indicate that the Early Cretaceous Albian-Middle Jurassic Bajocian seawater serves as an important source of potassium for potash deposition in the Simao Basin. The characteristics of the ratios of the Br/Cl (mmol/mol), K/Cl (mmol/mol), Rb/Sr (mol/mol), along with the contents of the Br and Rb, indicate that the most of potash in the Simao Basin is primary origin. Moreover, we have also provided new insight into the geochemical behaviors of K isotopes during the evolution of the evaporites. The precipitation of potash may be accompanied by K isotope fractionation, as evidenced by the lighter K isotope composition of carnallite compared to that of sylvinite. K isotope fractionation occurs between the secondary sylvite and its parent source, and newly precipitated solids are characterized by relatively light K isotope Episodic freshwater inflow into the evaporative basin stimulates microbial activity, leading to fluctuations in K isotopes in the precipitated potash during the same evaporation stage. Therefore, this work not only provided direct evidence from the K isotopes for determining the origin of the potash in the Simao Basin but also further perceived the geochemical behaviors of K isotopes during the evolution of evaporite.

Bioinspired Composite Fabrics with Nanoneedle Structures for High Wicking-Evaporation performance

Achieving ultrafast antigravity water transport and evaporation in high-performance moisture-wicking fabrics remains a significant challenge in textile engineering. In this study, we introduce two novel asymmetric composite fabrics, NN-TS/PET/BS and NS-TS/PET/BS, developed through a straightforward one-step method. These fabrics incorporate different hydrophilic nanostructures—nanoneedles (NN) and nanosheets (NS) of cobalt carbonate—to enhance wicking-evaporation capabilities. The NN-TS/PET/BS fabric exhibited superior unidirectional water transport and evaporation performance, achieving a one-way transport value (R) of up to 330 %, an outstanding overall moisture management capacity (OMMC) of 0.87, and a rapid water evaporation rate of 0.5 g h⁻¹, which is 2 and 2.3 times higher than that of NS-TS/PET/BS and Coolmax, respectively. Detailed analyses revealed that the curvature gradients in the nanoneedles significantly enhanced the wetting and evaporation stages, facilitating efficient antigravity water transport. Wear studies confirmed that the NN-TS/PET/BS fabric could swiftly remove sweat from the skin surface, enhancing comfort and performance. These findings offer new perspectives for developing high-performance unidirectional water transport fabrics with broad application potential, including smart textiles, fog harvesting, and wound dressings.

Conceptual and Applied Aspects of Water Retention Tests on Tailings Using Columns

The water retention capacity of porous materials is crucial in various geotechnical and environmental engineering applications such as slope stability analysis, landfill management, and mining operations. Filtered tailings stacks are considered an alternative to traditional tailings dams. Nevertheless, the mechanical behaviour and stability of the material under different water content conditions are of concern because these stacks can reach considerable heights. The water behaviour in these structures is poorly understood, particularly the effects of the water content on the stability and potential for liquefaction of the stacks. This study aims to investigate the water retention and flow characteristics of compacted iron ore tailings in high columns to better understand their hydromechanical behaviour. The research used 5 m high columns filled with iron ore tailings from the Quadrilátero Ferrífero region in Minas Gerais, Brazil. The columns were prepared in layers, compacted, and instrumented with moisture content sensors and suction sensors to monitor the water movement during various stages of saturation, drainage, infiltration, and evaporation. The sensors provided consistent data and revealed that the tailings exhibited high drainage capacity. The moisture content and suction profiles were effectively established over time and revealed the dynamic water retention behaviour. The comparison of the data with the theoretical soil water retention curve (SWRC) demonstrated a good correlation which indicates that there was no hysteresis in the material response. The study concludes that the column setup effectively captures the water retention and flow characteristics of compacted tailings and provides valuable insights for the hydromechanical analysis of filtered tailings stacks. These findings can significantly help improve numerical models, calibrate material parameters, and contribute to the safer and more efficient management of tailings storage facilities.

Evaporation of stable microemulsion droplets

Emulsion fuels have the potential to reduce both particulate matter and NOx emissions and can potentially improve the efficiency of combustion engines. However, their limited stability remains a critical barrier to practical use as an alternative fuel. In this study, we explore the evaporation behavior of thermodynamically stable water-in-oil microemulsions. The water-in-oil microemulsion droplets prepared from different types of oil were acoustically levitated and heated using a continuous laser at different irradiation intensities. We show that the evaporation characteristics of these microemulsions can be controlled by varying water-to-surfactant molar ratio (ω) and volume fraction of the dispersed phase (ϕ). The emulsion droplets undergo three distinct stages of evaporation, namely preheating, steady evaporation, and unsteady evaporation. During the steady evaporation phase, increasing ϕ reduces the evaporation rate for a fixed ω. It is observed that the evaporation of microemulsion is governed by the complex interplay between its constituents and their properties. We propose a parameter (η) denoting the volume fraction ratio between volatile and nonvolatile components, which indicates the cumulative influence of various factors affecting the evaporation process. The evaporation of microemulsions eventually leads to the formation of solid spherical shells, which may undergo buckling. The distinction in the morphology of these shells is explored in detail using scanning electron microscopy imaging.

Correlation effect between the capillary flow and evaporation rate of water in a 2-D photothermal membrane

To shed light on the correlation effect between the capillary flow and phase transition of water in photothermal evaporation, the non-equilibrium molecular dynamics (NEMD) simulations were employed to investigate the evaporation of water in Multilayered graphene oxide membranes. It was initially found that water molecules need to overcome strong energy barriers to migrate upward by layers before evaporation, with the energy barrier increasing with the reduction in nanogap, hydroxyl content, or increase in layer spacing of graphene sheets. The strong energy barrier accordingly results in dramatic sensible heat conversion and high evaporation temperature. It was shown that the enhanced temperature and hydrophilicity both weaken the hydrogen bond strength of water molecules confined in 2-dimensional channels, contributing to the reduced evaporation enthalpy. The preferential pathways in graphene channels or the weakened hydrogen bonds in hydroxyl-functionalized graphene of water molecules were found to be important influences on capillary flow energy consumption, leading to differences in evaporation energy supply. In combination with these effects, the evaporation rate could be increased by up to 2 folds and an interfacial enthalpy of evaporation below 1500 kJ kg−1 could be achieved by properly tuning the configuration and chemical properties of the graphene membrane. Our findings lay a theoretical foundation for providing a strategy to improve the interfacial evaporation performance in desalination.

Effect of the inclination angles of the capillary tube on the natural evaporation of absolute ethanol

Microchannel heat transfer plays an important role in microelectronics technology for heat dissipation, due to its high efficiency and low heat transfer temperature difference and flow resistance. To underpin the fundamental understanding of this technology, the natural evaporation process of absolute ethanol in a capillary tube at inclination angles ranging from 0° to 90° was investigated experimentally by exploring a spectrum of properties, such as Marangoni flow patterns, evaporation rate, heat flux, and temperature distribution. We found that the morphology of the meniscus is similar under different inclination angles, but the liquid and the tube wall slip to varying degrees due to the pressure difference at the liquid–vapor interface during evaporation. Therefore, the force distribution of the meniscus interface is different, and the resultant force is Fmax(60°) > Fmax(0°) > Fmax(30°) > Fmax(90°). We found that the morphology of the meniscus is independent of the inclination angle when absolute ethanol evaporates naturally. And the evaporation rate, heat flux and temperature distribution of meniscus at the initial stage of evaporation follow the law of resultant force distribution. That is, when the inclination angle is 60°, the evaporation rate and heat flux reach the maximum, i.e. 1.64 μm/s and 10.96 W/cm2, respectively, and the temperature between the center of the meniscus and the wedge region reaches 1.5 ℃. We used μ-PIV to observe the Marangoni vortex morphology of the vertical section of the meniscus, and found that there are different degrees of deformation at different inclination angles. When the inclination angle is 90°, the Marangoni vortex structure is destroyed.

Temperatures of AdS2 black holes and holography revisited

In a dilaton gravity model, we revisit the calculation of the temperature of an evaporating black hole that is initially formed by a shock wave, taking into account the quantum backreaction. Based on the holographic principle, along with the assumption of a boundary equation of motion, we show that the black hole energy is maintained for a while during the early stage of evaporation. Gradually, it decreases as time goes on and eventually vanishes. Thus, the Stefan–Boltzmann law tells us that the black hole temperature, defined by the emission rate of the black hole energy, starts from zero temperature and reaches a maximum value at a critical time, and finally vanishes. It is also shown that the maximum temperature of the evaporating black hole never exceeds the Hawking temperature of the eternal AdS2 black hole. We discuss physical implications of the initial zero temperature of the evaporating black hole.

Droplet–droplet vapor-mediated interactions in confined environments

The evaporation of multiple droplets ensues ubiquitously in nature and industry. Vapor mediation caused by evaporating neighboring droplets is a demonstrated phenomenon that shows that droplets can interact with each other via the vapor in both open and confined configurations, i.e., the “shielding effect.” However, interactions between paired droplets in confined environments, more common in industrial processes, remain unexplored. In this Letter, we experimentally investigate the evaporation of water based paired sessile droplets on hydrophilic glass slides at different spacings in the absence and presence of an enclosed chamber. The results demonstrate that a confined environment significantly attenuates droplet evaporation, which intensifies with decreasing spacing between droplets. A 30%–82% increase in the droplet lifetime is found for the shortest distance studied in a confined environment, while results in an open environment are provided as a control. Both the local shielding effect and the global vapor accumulation due to confinement collaboratively induce such strong evaporation suppression. In addition, two well differentiated evaporation regimes ensue in a confined environment where the shielding effect initially dominates the evaporation suppression, whereas confinement governs the later evaporation stage. The later stage accounts for over 60% of the droplet lifetime. Such transition and further evaporation suppression, when compared to the classical shielding effect, highlights the importance of a confined environment in multiple droplet evaporation.

Physics Of Two-Stage Evaporation Of Volatile Droplets Suspended In An Ultrasonic Levitator

The evaporation process of mono-component droplets in an ultrasonic levitator is experimentally monitored, focusing on three types of volatile liquids: methanol, ethanol, and 2-propanol. This investigation reveals a ‘two-stage’ evaporation process characterized by an initial rapid evaporation stage followed by a significantly slower evaporation stage; a pattern consistently observed across all three volatile liquids. However, for droplets of comparable size, methanol droplets evaporate faster in the rapid stage than ethanol and iso-propanol droplets and enter the slow evaporation stage earlier. On the other hand, during the slow evaporation stage, 2-propanol droplets exhibit the lowest evaporation rate compared to methanol and ethanol droplets. To explain the two-stage evaporation and the varying evaporation characteristics of mono-component droplets with different volatile components, the streaming patterns within the levitator, with and without a suspended droplet, are visualized and quantified using Particle Imaging Velocimetry (PIV). Two acoustic-induced jet flows, originating from the transducer and reflector of the levitator and considered as Eckart streaming, are observed within the empty levitator. These jet flows move toward the levitated droplet, influencing its evaporation process. Additionally, Stefan flow, carrying vapor away from the surface of the volatile droplet, is clearly observed due to rapid evaporation. The competition between Stefan flow and Eckart streaming ultimately determines the external streaming patterns around the investigated droplets. A theory combining the external streaming patterns and vapor enrichment is proposed to interpret the two-stage evaporation and the corresponding characteristics of the evaporating droplets suspended in the levitator. Furthermore, this study captures boundary-driven acoustic streaming near the droplet surface, known as Rayleigh–Schlichting streaming, whose dimensions and motion vary with the different liquid components and the properties of the corresponding vapor. In summary, the study highlights the presence of Eckart streaming in the ultrasonic levitator and Stefan flow outside an evaporating volatile droplet. Considering these flow patterns is essential for explaining the ‘two-stage’ evaporation and the relevant characteristics within the ultrasonic levitator.

Investigation of Desiccation Cracking Behavior of Waste Carbon Fiber–Reinforced Clay Material

Carbon fiber is a common waste building material, but its effect on the drying and cracking properties of clay materials is unknown. In this paper, crack rate and fractal dimension are used to characterize the influence of waste carbon fiber materials on the development of soil cracking. With the rise in carbon fiber content to 0.2%, 0.4% and 0.6%, the crack rate of soil cracking decreased by 7.9%, 17.3% and 23.3%, respectively, while the fractal dimension of soil cracking decreased by 2.4%, 8.7% and 21.2%, respectively. Accordingly, the critical moisture content of the soil samples increased by 33.2%, 110% and 151%, and the time of the soil constant evaporation stage decreased by 5.1%, 13.8% and 34.5%, respectively. When carbon fiber is combined with soil, carbon fiber will increase the interface bonding strength, friction and interlocking force, effectively inhibiting the cracking of soil, and it provides a channel for water transport in the soil in the early stage.

Experimental investigation on enhanced combustion of methanol/heavy fuel oil by droplet puffing at elevated temperatures

To achieve high-efficiency combustion of heavy fuel oil (HFO), this study investigated the combustion characteristics of methanol/HFO droplets with methanol content from 10 to 30% using the suspension method under ambient temperature from 923 to 1023 K. The combustion of methanol/HFO droplets was summarized as a two-phase process consisting of six typical stages, emphasizing liquid phase. Especially, the fluctuation evaporation stage, induced by frequent and intense puffing, was identified as prominent character. Both the ignition delay and lifetime of HFO and methanol/HFO droplets decreased with increasing ambient temperatures. For the methanol/HFO droplet, the ignition delay and droplet lifetime increased with the increasing methanol content. Prominently, compared to HFO, HM10 had the most significant reduction in droplet lifetime and TINL under the same operating conditions, which indicated that the addition of 10% methanol accelerated the combustion process and reduced soot generation. Additionally, the thermos-dynamic characteristics of methanol/HFO droplets were investigated. Puffing was primarily attributed to superheating of methanol and pyrolysis of heavy components in HFO, which resulted in active and passive rupture of bubbles. Similarity and maximum deformation were employed to qualitatively distinguish between them. The obtained findings aimed to develop a promising alternative fuel to reduce emissions and preserve energy.

Rancangan e-LKPD Berbasis Collaborative Creativity Learning (CCL) Pokok Bahasan Perpindahan Kalor Pada Mesin Pembuatan Gula Pasir

Physics as a subject matter involves understanding concepts and mathematical applications that are often a challenge for students, for example the concept of heat transfer. To provide a memorable and interesting learning experience, the context of the e-LKPD design can be taken from everyday life, such as the process of making granulated sugar in a sugar factory. The process involves the concept of heat transfer, for example the stages of evaporation and crystallisation of neera. The purpose of this study was to analyse the validity of the design and learners' responses to the e-LKPD design. This type of research is development research with the ADDIE model and is limited to the development stage. Data collection involved literature study, observation, interviews, questionnaires, and documentation. The validation results obtained an average percentage value of 87.33%, with a very feasible category and learner responses showed a high level of interest, with a percentage value of 83%. Thus, e-LKPD based on collaborative creativity learning (CCL) on the subject of heat transfer in sugar making machines can be considered feasible and can be implemented effectively to students in learning activities.

Technology of flame‑induction heating of ferrous metal shavings in hot briquetting installations

As a result of the study of flame‑induction heating of steel and cast iron shavings, optimal heating modes, dimensions of the furnace and the ratio of the sizes of its components (gas‑flame and induction heaters) were established, which served as the basis for the development of a new heating technology, which ensures minimization of dimensions in comparison with known analogues, increasing the productivity and efficiency of the furnace. It has been established that at the stage of evaporation and removal of water vapor and light oil fractions from the chips in the temperature range of 100–550 °C until the optimal oil concentration of 1.5–3.0 % is achieved, among all known methods of muffle heating, gas‑flame heating is the most economical and productive heating, and subsequently, when heating a dehydrated porous mass of metal with a density of 1100–1700 kg/m3 to 850 °C – induction heating in an atmosphere of products of thermal sublimation and destruction of coolant. It is advisable to carry out induction heating with a current frequency of 2.0–2.4 kHz with a ratio of the lengths of the gas‑flame and induction heating zones of 2.0–2.5 and the dimensions of the inductor (height to hole diameter) of 3.7–4.0. The degree of oxidation of hot‑pressed briquettes corresponds to the initial oxygen content in the chips: for steel – 1.3–1.7 %, for cast iron – 0.46–0.47 %. The data obtained made it possible to develop a technology for flame‑induction heating of ferrous metal shavings, as well as the design of a small‑sized furnace with a specific productivity of 6500–9500 kg/m2·h and an efficiency of 40–45 %.

Component Effects in Binary Droplet Impact Behaviors on the Heated Plate: Comparison Study of Ethanol/Propanol and Ethanol/Water Droplets and Observation of Novel Bubble Shrinkage Phenomenon

This work aims to investigate the effect of liquid physical properties on the behavior of binary droplets impact on the heated smooth aluminum alloy plate with a high-speed imaging system. Two groups of mixed solutions with similar boiling point differences are selected as the working liquid, in which the low-boiling-point components are both ethanol and the high-boiling point components are propanol and water, respectively. Compared to the ethanol/propanol binary droplets, the experimental results show that the ethanol/water binary droplets have diverse impact phenomena and significantly broad transition boiling regimes, as well as the reduced droplet residence time and increased Leidenfrost temperature point. With the decreasing ethanol content in ethanol/water binary droplets, these effects become more prominent. For secondary atomization, the ethanol/water binary droplet undergoes parent droplet breakup into fragment droplets with larger diameters (Ds > 0.3 mm). Both binary droplets produce satellite droplets with small diameters (Ds < 0.3 mm) by puffing and ejection. In terms of the ethanol/propanol binary droplet impact, the probability of puffing is higher and the satellite droplet diameters are small. In the ethanol/water binary droplet impact, the probability of ejection is higher and the satellite droplet diameter distribution is wider. When an ethanol/water binary droplet of 25 vol.% ethanol content impacts the heated wall at Ts = 120 °C, a novel large bubble shrinkage phenomenon occurs at the late stage of droplet evaporation. This phenomenon is proposed to be relevant to the increasing surface tension and saturation temperature with decreasing ethanol content, as well as the decreasing ambient temperature above the top surface of the bubble.

Experimental Study on Evaporation and Micro-Explosion Characteristics of Ethanol and Diesel Blended Droplets

In this study, the constant temperature control system of a heating plate was established, ethanol–diesel fuel with different proportions was prepared, and a series of experiments were carried out. The experimental system was used to observe, summarize, and analyze four evaporation and crushing modes of mixed droplets, which were explosion, liquid filament stretching, exocytosis, and ejection mode. The evaporation process of four kinds of mixed droplets in their life cycle was analyzed by normalizing the diameter square. It was proposed that the evaporation process of droplets could be divided into the following three stages: a heating stage, a fluctuating evaporation stage, and an equilibrium evaporation stage. It was also pointed out that the expansion, ejection, and micro-explosion of droplets were the causes of fluctuating evaporation. The concept of expansion and crushing intensity was put forward and the expansion and crushing intensity of ethanol/diesel mixed droplets with different proportions were calculated. The reasons why expansion and crushing intensity first increased and decreased with the increase in ethanol blending ratio were analyzed. Finally, the time proportion of ethanol–diesel mixed droplets in each evaporation stage was calculated, which explained that the time proportion of the instantaneous heating stage showed a parabolic law with the increase in ethanol content.

Heat transport during drop impact onto a heated wall covered with an electrospun nanofiber mat: The influence of wall superheat, impact velocity, and mat thickness

Nanofiber surface coating is a promising method for the enhancement of heat transfer during spray cooling. In the present work, the drop dynamics as well as local and overall heat transfer during single drop impact onto a heated wall covered with a polyacrylonitrile (PAN) nanofiber mat are investigated to obtain insight into the mechanisms governing the heat transport enhancement. The influence of wall superheat, drop impact velocity, and mat thickness on the hydrodynamics and heat transfer from the heated wall to the fluid is studied. The experiments were conducted inside a temperature-controlled test cell with a pure vapor atmosphere maintained with refrigerant FC−72 (perfluorohexane). The temperature field at the solid–fluid interface was observed with a high-speed infrared camera, and the heat flux field was derived by solving a three-dimensional transient heat conduction equation within the substrate. The presence of the nanofiber mat on the heater surface suppresses the drop receding phase due to the pinning of the contact line at the end of the spreading phase. Two different heat transfer scenarios are observed depending on the wall superheat and drop impact velocity: scenario (I), in which the liquid drop completely penetrated through the porous nanofiber mat and made contact with the heater surface; and scenario (II) in which the vapor produced inside the pores of the nanofiber mat prevented the liquid drop from touching the heater surface. In scenario (I), an up 450% heat flow enhancement during the sessile drop evaporation stage has been observed. In scenario (II), a 80% heat flow enhancement at this stage has been registered.

Detection of risk areas in dairy powder processes: The development of thermophilic spore forming bacteria taking into account their growth limits

Anoxybacillus flavithermus, Geobacillus stearothermophilus and Bacillus licheniformis are the main contaminants found in dairy powders. These spore-forming thermophilic bacteria, rarely detected in raw milk, persist, and grow during the milk powder manufacturing process. Moreover, in the form of spores, these species resist and concentrate in the powders during the processes. The aim of this study was to determine the stages of the dairy powder manufacturing processes that are favorable to the growth of such contaminants. A total of 5 strains were selected for each species as a natural contaminant of dairy pipelines in order to determine the minimum and maximum growth enabling values for temperature, pH, and aw and their optimum growth rates in milk. These growth limits were combined with the environmental conditions of temperature, pH and aw encountered at each step of the manufacture of whole milk, skim milk and milk protein concentrate powders to estimate growth capacities using cardinal models and the Gamma concept. These simulations were used to theoretically calculate the population sizes reached for the different strains studied at each stage in between two successive cleaning in place procedures. This approach highlights the stages at which risk occurs for the development of spore-forming thermophilic bacterial species. During the first stages of production, i.e. pre-treatment, pasteurization, standardization and pre-heating before concentration, physico-chemical conditions encountered are suitable for the development and growth of A. flavithermus, G. stearothermophilus and B. licheniformis. During the pre-heating stage and during the first effects in the evaporators, the temperature conditions appear to be the most favorable for the growth of G. stearothermophilus. The temperatures in the evaporator during the last evaporator effects are favorable for the growth of B. licheniformis. In the evaporation stage, low water activity severely limits the development of A. flavithermus.

Perturbative and semi-analytical solutions to Teukolsky equations for massive fermions

In this work, we aim at solving the Teukolsky equations for a fermion with mass m e ≠ 0 in the presence of a rotating black hole with mass M. We consider two different regimes: m˜e=M−1me≪1 and a ω ≪ 1; m˜e≪1 and a ω ≳ 1. We treat each of these two regimes in different ways: we use a perturbative approach for the first, similar to the usual one employed for spin 0, 1, 2 and mass-less 1/2 fields, but with two small parameters (aω and m˜e ); as we shall see, the second can be treated with a semi-analytical approach. In a forthcoming paper we shall study the remaining two cases in which m˜e≳1 , while a ω ≪ 1 or a ω ≳ 1. The regime with m˜e≪1 , but a ω ≳ 1 is probably the most interesting from the astrophysics point of view, but this last two cases might be of some interest for the study of the interaction of fermions with very small black holes, which may be formed, for example, in the last stages of the Hawking evaporation.

Investigation on structure, evaporation, and desiccation cracking of soil with straw biochar

AbstractTo investigate the cracking behavior in the evaporation process of the soil surface with biochar as an additive, five experimental groups were established in the natural environment with 0, 12, 60, 120, and 170 g·kg−1 biochar. The results of an investigation on organic matter and aggregations indicate that a high content of biochar can significantly improve the content of organic matter and the amount of soil aggregates. After adding 60 and 170 g·kg−1 biochar, the content of organic matter increased by 19.47% and 84.12%, respectively, and the content of soil aggregates with an average diameter greater than 0.25 mm increased by 16.43% and 38.20%, respectively. The investigation also examines the evaporation and cracking characteristics of soils that contain biochar. The rate of evaporation is approximately a “step” type function with time. The rate of evaporation is observed in three stages: the rapid, decelerating, and final evaporation stages. In the rapid evaporation stage, the initial evaporation rate of the sample that contains biochar is increased on average by 46%. The fractal dimension and cracks rate are decreased by 22.95% and 20.99% with 120 g·kg−1 biochar addition. This means that the increase of soil organic matter after adding biochar plays a crucial role in the stability of aggregates. As a soil conditioner, biochar has the ability to enhance soil water retention capacity and is a sustainable strategy to improve soil properties.