Vapor Formation Research Articles

The Generation Methods and Applications of Cavitating Jet by Using Bubble Collapse Energy

Cavitation is a dynamic process characterized by the formation, growth, and collapse of vapor or gas vacuoles in liquids or at the liquid–solid interface, initiated by a local pressure drop. This phenomenon releases concentrated energy through microjet impacts and shock waves, leading to a violent exchange of energy with the surrounding environment. While cavitation is often perceived as detrimental, certain aspects can be harnessed for practical applications. Relevant studies have shown that cavitating jets provide high operating efficiencies, reduce energy consumption per unit, and have the potential for waste treatment. This paper presents three types of cavitating jets: central body cavitation, oscillatory cavitation, and shear cavitation. Additionally, the formation process of a cavitating jet and the effects of various factors on jet performance are discussed. Following an in-depth examination of the cavitation phenomena, subsequent chapters explore the applications of cavitating jets in material surface enhancement, cleaning, and energy exploration. Furthermore, recommendations for future research on cavitating jets are provided. This paper provides a comprehensive literature review on cavitating jets.

Enhancement of hydrogen production from thermal and catalytic cracking of HDPE through Implementation of activated biochar

This study investigated hydrogen production characteristics from thermal and catalytic cracking of high-density polyethylene (HDPE) and role of activated biochar derived from biomass (palm kernel shell, PKS). The objective was to enhance hydrogen yield in response to growing demands for hydrogen and the management of waste plastic. Three experimental setups—pyrolysis, thermal cracking, and char cracking—were employed in a two-stage pyrolysis system to examine the impact of reaction temperature and activated biochar on 1) the decomposition of HDPE into tar, which is a complex hydrocarbon mixture, and 2) the production of hydrogen from the vaporized tar. The findings indicated that the reaction temperature in the first reactor influenced tar vapor formation, whereas the temperature in the second reactor was more closely associated with the production of hydrogen and lighter hydrocarbons such as methane. Under identical temperature conditions, the use of activated biochar increased the hydrogen production by more than six times and adsorbed the solid carbon, resulting in no visible carbon particles. Although the reaction temperatures in this study were higher than those in previous studies involving other catalysts, leading to increased energy costs, the abundant biomass sources for carbon activation and the simplicity of the manufacturing process could position activated biochar as a viable catalyst for the thermochemical recycling of plastic into energy source.

Study of a Cavitation Treatment in Kaplan Hydro-turbine

Abstract This research proposes an air-injection treatment for the cavitation phenomena in the Kaplan turbine. An unsteady numerical model is created to predict the cavitating flow through a 3-inch axial hydro turbine before and after the air injection. Pressurized air [jet-in-crossflow] injection is set to be through the turbine housing, and the configuration was altered between 1, 2, 4, and 12 circumferential jets to test the effects of air mass flow rate and injection distribution. Interactions between three fluids (liquid water, water vapor, and air) were considered by utilizing the physics models of Volume of Fluid (VOF) multiphase, Cavitation, and Large Eddy Simulation (LES) turbulence. Surface and time-average results are to be compared with a baseline case of pure cavitation. With the vapor volume fraction created on the rotor components during the cavitation, the absolute pressure scenes clarified the connection between the air treatment and cavitation reduction. While rotation causes negative pressure in the system, the injected air is sucked to such low-pressure zones, and consequently, increasing the absolute pressure above the vapor limit reduces the vapor formation. Preliminary outcomes at 1000 rpm show a 55 percent reduction in the formed vapor on the blades after air injection by a time corresponding to 6 cycles of the turbine. A corresponding mechanical power of 12 percent increase was observed. Moreover, the curve fitting of the data shows that the vapor reduction and power regain are in 2nd order correlation with the increased air volume.

Теплоотдача при движении воды в трубе при температурах, близких к температурам кипения в переходном режиме

Currently, there is a problem of developing effective methods to calculate heat and mass transfer processes during steam condensation from a vapor-gas mixture in industrial devices. This is due to the need to create new reliable and highly efficient designs of heat exchangers for various purposes. The finite element method has been used in the ANSYS Fluent software package during the numerical simulation. An experimental plant is tested in the pipeline of an industrial enterprise at the production site of the Technopolis KHIMGRAD industrial park (Kazan-city). The applicability of the Lee model to solve problems of water flow in a pipeline with partial evaporation is proved. This model allows you to accurately account for the processes of evaporation and condensation, which is important for the design of cooling and air conditioning systems. The authors have designed a three-dimensional model of the flow area of the experimental module and a CFD model to calculate temperatures, phase velocities and their concentrations, considering the peculiarities of the ongoing processes of heat and mass transfer. A slight effect on the heat flow of a 180° rotation during the flow of a liquid medium in the range of the Reynolds numbers 1800–2600 is shown. The developed model is verified with the results obtained at the experimental plant. It is established that the model reproduces experimental data well. An analysis of studies of heat and mass transfer processes during the fluid flow in channels in the presence of phase transitions is carried out. The problems of calculating the parameters of heat transfer during the movement of a fluid in a transient mode are revealed, especially at values of the Reynolds number close to 2000. The experimental plant diagram is presented. It is found that in the range of Reynolds numbers of 2600–3600, the calculated temperature values differ from the temperature values obtained experimentally by less than 0,42 %. During the partial transition of water into steam in the range of Reynolds numbers of 1800–2600, the deviations were less than 6 %, which confirms the adequacy of numerical modeling of calculating the heat transfer process in a pipe. It is shown that considering the influence of temperature on surface tension, the coefficient of thermal conductivity of water and the coefficient of dynamic viscosity of water is important to obtain accurate results. The proposed approach can be used to optimize the operating parameters of condensers and evaporators, as well as to accurately calculate the heat transfer coefficient and determine the areas of vapor formation. It will improve the energy efficiency of industrial installations and reduce the cost of equipment operation.

Thermal and Moisture Content Monitoring of a Full-Scale Load Bearing Hemp Lime Arch Prototype

Today, bio-sourced materials represent an important technological field of study, as they could sink atmospheric carbon dioxide into buildings. Little-processed construction materials would also reduce the environmental impact of the construction sector, which emitted more than 2.9 Mt of CO2 in 2020. Hemp-lime is a material that meets both these requirements. It is an insulating mix that can take different forms and be used in various parts of a building. The challenge is providing it with enough mechanical strength to make it loadbearing, at least to some extent. This research focuses on the construction and monitoring of a pointed arch, based on a previous experimental hemp-lime construction at Cardiff University in 2009, under the direction of architect David Lea. Since 2022, such an experiment on a possible loadbearing hemp-lime mix is being repeated at the Politecnico di Torino as part of a wider project called “experimental pavilions of vegetarian architecture”. The design and numerical analysis of the Cardiff prototype led to the modification of both the geometry and the composition of the mix using only pozzolanic air lime as the binder. The construction of the arch ended in December 2023. Observing the thermo-hygrometric conditions of this hemp-lime mix once in place is the main purpose of this article. A strong correlation is revealed between outdoor conditions with temperature and moisture content in the core of the arch. Building a full-size outdoor prototype allows for the avoidance of mathematical correction to the results obtained and allows the assessment the mix’s resistance in relation with environmental conditions. Due to some similarities of nature and function between lime and cement, many studies of lime mixes do not exceed a duration of 28 days, which cannot be considered the appropriate observation time for its curing. Therefore, we analysed this lime-based material for around 6 months, according to its own temporality and chemical kinetics. Through continuous monitoring at 10-min intervals, it was possible to highlight several significant aspects of rammed hemp-lime. The results show that the temperature within the mix is influenced by the outside temperature, but the sun exposure of certain areas drives up the corresponding temperature values more rapidly. Furthermore, while the absorption of water in the form of vapour is very rapid, desorption takes longer, as does re-establish a balance between the material and its context. Finally, solar exposure affects particularly 30-cm-thick elements, while elements that are 60 cm thick are not affected in the short term but only in long-term exposure conditions like season changes.

Heat Transfer and the Formation of Vapor Bubbles When Boiling a Magnetic Fluid on a Single Center of Vapor Formation in an Alternating Magnetic Field

Heat Transfer and the Formation of Vapor Bubbles When Boiling a Magnetic Fluid on a Single Center of Vapor Formation in an Alternating Magnetic Field

Separation of multicomponent gas mixtures

In the production of granular organo-mineral fertilizers using the fluidization technique by dehydrating heterogeneous liquids, as an energy-efficient technology, there is a need to purify the spent coolant containing solid particles, dust and a significant amount of water vapor. Solid particles up to 20 microns in size are effectively captured in cyclone devices. To further capture water vapor and fine solid particles, a scrubber is used with an additional circulation circuit involving an additional bone of water, which, upon reaching a concentration of more than 20%, is discharged back to the granulation stage. This leads to an increase in energy consumption for production in general. Condensation of vapors in a dispersion containing 5-7% (w/w) moisture in the form of water vapor at the second stage of purification will increase the level of environmental safety in production. To select an innovative method of separation of multicomponent gas dispersions accompanied by a change in the aggregate state and a rational design of the apparatus, a review of scientific articles and developments such as systematization of existing methods was carried out. Such an approach makes it possible to choose the optimal solution for the separation of gas-dust and gas-liquid flows in the conditions of the existence of a large number of types of equipment design and the level of their innovation. In addition to the rational design of the devices, great attention was also paid to the issues of energy efficiency, resource saving and ensuring the state of environmental safety at production facilities in the conducted research. Based on the results of the analysis, it is proposed to use a scheme of consecutively installed cyclones CN-11 and SK‑CN-33. It is proposed to use the ЦН-11 cyclone for the preliminary capture of highly dispersed dust, and the SK-CN‑33 for condensation and capture of water vapor and solids not caught in the previous cyclone particles.

The role of carbon textile surface functionalities in reactive adsorption of vapor and liquid 2-chloroethyl ethyl sulfide: Evaluating interactions at the interface

A carbon textile (CT) was chemically modified to increase its surface activity and promote the adsorption and degradation of 2-chloroethyl ethyl sulfide (CEES) - a surrogate for mustard gas. CT was initially subjected to oxidation (CTO), and then heated under ammonia (CTON) or hydrogen sulfide (CTOS) atmosphere to incorporate nitrogen or sulfur functionalities, respectively. Detoxification experiments were performed in closed vials using either vapor or liquid forms of CEES. The maximum vapor weight uptakes on CT, CTO, CTOS, and CTON were 399, 372, 434, and 489 mg/g, respectively. All textiles were able to prevent the vaporization of CEES liquid droplets. Although similar reaction products were detected in both vapor and liquid systems, the marked differences in the extent of CEES chemical transformation on the surfaces of the textiles indicate distinct detoxification pathways influenced by surface chemistry. Even though the heterogeneous surface of CTO, enriched with oxygen surface groups, facilitated various reactions, hydrolysis was the predominant pathway. The thermal treatment, regardless of the atmosphere, reduced the oxygen content, decreasing the extent of hydrolysis. However, incorporating basic surface groups such as pyridines, amines, or weak acids such as thiols promoted dehydrohalogenation as the main detoxification pathway on these samples.

Numerical investigation of arc characteristics and metal properties in ELAMF-assisted WAAM with wire retraction

In this study, a multi-physics integrated model of wire arc additive manufacturing (WAAM) with wire retraction and external longitudinal alternating magnetic field (ELAMF) assistance is proposed and validated, and the effect of ELAMF on the arc plasma characteristics and metal properties are systematically and quantitatively investigated. The model comprehensively takes the arc plasma heating, wire dynamic retraction, droplet transfer, the formation and diffusion of metal vapor, the melting and solidification of molten metal, and the stirring effect of ELAMF into account. The simulated results show that ELAMF has compressed the arc morphology, and decreased the temperature, potential, current density and static pressure, which are most pronounced when the wire is at an elevated position and the transient current is at its peak phase. Meanwhile, the formation of low-temperature and low-velocity cavities in the center of arc column are promoted by ELAMF, consequently diminishing the energy transferred from the arc plasma to molten pool through thermal conduction and mitigating the squeezing of the arc plasma on the surface of molten pool. The results also demonstrate that the ELAMF has reduced the temperature gradient of liquid metal inside the molten pool, and intensified the forced convection for the occurrence of multiple circulations.

Identifying predictors of multi-year cannabis vaping in U.S. Young adults using machine learning

IntroductionIncreasing number of current cannabis users report using a vaporized form of cannabis and young adults are most likely to vape cannabis. However, the number of studies on cannabis vaping is limited, and predictors of cannabis vaping among U.S. young adults remain unclear. Previous studies on cannabis vaping have known limitations, as they (1) relied heavily on regression-based approaches that often fail to examine complex and non-linear interactive effects, (2) focused on examining cannabis vaping initiation but not on its use over multiple years, and (3) failed to account for recreational cannabis legalization (RCL) status. MethodsThis study was a secondary analysis of the restricted use files of the Population Assessment of Tobacco and Health Study, Waves 4–6 (December 2016-November 2021). A two-stage machine learning approach, which included Least Absolute Shrinkage and Selection Operator (LASSO) and Classification and Regression Tree (CART), was used to identify predictors of multi-year cannabis vaping while accounting for state-level RCL status among a representative sample of U.S. young adults. ResultsStratified CART created a five-terminal-node prediction model for states with RCL (split by cannabis use, cigarette use, bullying behavior, and ethnicity) and a different five-terminal-node prediction model for states without RCL (split by cannabis use, heroin use, nicotine vaping, and hookah use). ConclusionsCharacteristics predicting multi-year cannabis vaping appear to differ from those of cannabis vaping initiation. Results also highlight the importance of accounting for RCL status because predictors of cannabis vaping may differ for individuals living in states with and without RCL.

Integrated evaluation of workplace exposures and biomarkers of bladder cancer among textile dyeing workers

BackgroundThe textile industry is the second risk factor for bladder cancer, after smoking. Previous studies focused on the impact of exposure to high concentrations of bladder carcinogenic chemicals in the textile dyeing industry on the elevation of bladder cancer biomarkers. This study aimed to evaluate bladder carcinogenic air pollutants in a textile dyeing factory and investigate its role and the role of serum 25-hydroxyvitamin D (25-OH vit. D) on cancer bladder biomarkers in exposed workers.MethodsA cross-sectional study was conducted. Particulate and vapor forms of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) were monitored in the printing, dyeing, and preparing sections of a textile factory. Bladder tumor antigen (BTA), nuclear matrix protein 22 (NMP-22), and 25-OH vit. D were estimated in all the exposed workers (147 exposed workers) and in workers not occupationally exposed to chemicals (130 unexposed workers).ResultsAromatic bladder carcinogenic compounds were either in low concentrations or not detected in the air samples of working areas. BTA and NMP-22 of exposed workers were not significantly different from the unexposed. However, 25-OH vit. D was significantly lower in the exposed than unexposed workers. There was a significant inverse correlation between 25-OH vit. D and duration of exposure in exposed workers.ConclusionThe mean levels of PAHs and VOCs were within the safe standard levels in the working areas. The non-significant difference in BTA and NMP-22 between the exposed and unexposed groups suggests the presence of occupational exposures to safe levels of bladder carcinogenic aromatics, while the significantly lower 25-OH vit. D levels among the exposed than the unexposed groups could suggest the potential association of 25-OH vit. D with occupational exposures to low levels of PAHs and VOCs, and this association was found to be inversely correlated with the duration of exposures. Accordingly, more specific predictor tests must be applied for early diagnosis of bladder cancer among the exposed workers.

New insights on cavitating flows over a microscale backward-facing step

This study introduces the first experimental analysis of shear cavitation in a microscale backward-facing step (BFS) configuration. It explores shear layer cavitation under various flow conditions in a microfluidic device with a depth of 60 μm and a step height of 400 μm. The BFS configuration, with its unique characteristics of upstream turbulence and post-reattachment pressure recovery, provides a controlled environment for studying shear-induced cavitation without the complexities of other microfluidic geometries. Experiments were conducted across four flow patterns: inception, developing, shedding, and intense shedding, by varying upstream pressure and the Reynolds number. The study highlights key differences between microscale and macroscale shear cavitation, such as the dominant role of surface forces on nuclei distribution, vapor formation, and distinct timescales for phenomena like shedding and shockwave propagation. It is hypothesized that vortex strength in the shear layer plays a significant role in cavity shedding during upstream shockwave propagation. Results indicate that increased pressure notably elevates the mean thickness, length, and intensity within the shear layer. Instantaneous data analysis identified two vortex modes (shedding and wake modes) at the reattachment zone, which significantly affect cavitation shedding frequency and downstream penetration. The wake mode, characterized by stronger and lower-frequency vortices, transports cavities deeper into the channel compared to the shedding mode. Additionally, vortex strength, proportional to the Reynolds number, affects condensation caused by shockwaves. The study confirms that nuclei concentration peaks in the latter half of the shear layer during cavitation inception, aligning with the peak void fraction region.

A practical method for the in-situ estimation of the effective thermal resistance of gas diffusion layers in PEMFC

The membrane electrode assembly of a PEM fuel cell is hotter than the gas feeding plates because heat is generated within it, and the diffusion layers are thermally resistive. The temperature gradient created, which increases as a function of the current density, is useful for evacuating the water produced in vapor form. This water transport mechanism is known as the “heat pipe effect”. The temperature gradient produces a saturation vapour pressure gradient, which in turn produces a diffusive vapor flow. Mastering water management, coupled with heat management, requires knowledge of the temperature of the MEA and therefore the effective thermal resistance of the diffusion layers. In this paper, we present an original method for estimating this thermal resistance in situ, without using heat flux sensors or directly measuring the temperature of the MEA. The method requires the ability to impose a temperature gradient between the anode and cathode plates, and to perform a hot-side water balance. Thermal resistance is deduced from the coupling between heat and water transfer. Two diffusion layers widely used by the community are tested. The GDL Sigracet 22 BB (from SGL Carbon) has a lower effective thermal resistance than the GDL Freudenberg H15C14. Variations in these thermal resistances are measured as a function of the temperature gradient imposed and of the compression ratio.

Thermo-Mechanical Properties and Benefits of Borosilicate Glass for SOEC Sealants

Boro-silicate glass materials have ideal properties for sealing oxidizing and reducing environments and electrically insulating solid oxide electrolysis cells (SOEC), while maintaining a glassy phase at high temperatures (750-900°C) to minimize chemo-mechanical degradation and gas permeability 1,2. Glass seals are typically applied as a slurry; hence, they are also expected to have non-wetting properties to prevent glass infiltration into the porous electrode structures during manufacturing 3. During the first startup, the initial temperature ramp serves to evaporate any binder in the slurry and to go through the glass transition phase, which cures the glass and increases hardness to improve resistance to creep. Typical glass materials operate in visco-plastic regimes (i.e., beyond the material’s glass transition temperature) and must be chemically stable while operating in steam-rich and oxygen-rich environments. To fully understand the performance of borosilicate glass seals, optimize the manufacturing, assembly, and maintenance of SOEC, we must be able to measure and analyze the glass material properties (i.e., glass transition temperature, coefficient of thermal expansion, modulus, creep, hardness) at the same operating conditions relevant for SOEC operation. In this work, we characterize the thermo-mechanical properties of borosilicate glass powder and sintered samples at various temperatures (ranging from ambient to 850°C), and at different aging conditions (i.e., atmosphere composition, temperature, and duration). The atmosphere composition is changed between air, steam-N2 mixtures, and H2-N2 mixtures to evaluate the chemical stability of borosilicate glass relating to the possible depletion of boron and silicon via the formation of boron hydroxide and silicon vapor when exposed to steam- and hydrogen-rich environments. The aging temperature and duration is varied to evaluate the crystallization kinetics, particle size growth, and its effect on mechanical properties. We employ a combination of Simultaneous Thermal Analysis - STA (i.e., combined Thermogravimetric Analysis - TGA, Differential Scanning Calorimetry - DSC, Fourier Transform Infrared - FT-IR spectroscopy, and Quadrupole Mass Spectroscopy - QMS), and nanoindentation as characterization techniques, while surface roughness is estimated with a 3D confocal optical microscope.Surface roughness varies between 0.83-1.38 𝜇m ± 1.1-1.76 𝜇m (Sa ± Sq). Both powder and solid samples are analyzed via STA with sequential temperature ramps (constant heating rate at 10 K/min in Ar atmosphere) up to 1500°C to estimate the effect of crystallization and particle size on the glass transition onset. For a sample aged at 850°C for 340 h, the first ramp shows typical DSC exothermic peaks (mW/mg) at around 800°C, with a midpoint glass transition occurring at 900°C. However, on the second ramps, peaks lower to around 500°C and the glass transition is estimated to be around 700°C. Subsequent tests consistently mirrored the trend of the second temperature ramp, showing minimal deviation and influence of crystallization and particle growth. Nanoindentation is performed between room temperature and 600°C to characterize both sintered glass samples “as-received” and aged at temperatures between 750-950°C for 340 h. Comparing a sample aged at 750°C with an “as-received” sample, the elastic moduli equally decreased from 100 GPa at room temperature to 40 GPa at 600°C, with comparable hardness values ranging from 10 GPa at room temperature to 0.5-0.9 GPa at 600°C, respectively. A.G. Sabato, G. Cempura, D. Montinaro, A. Chrysanthou, M. Salvo, E. Bernardo, M. Secco, F. Smeacetto, Journal of Power Sources, 328, 262-270 (2016)Dilshat U. Tulyaganov, Allu Amarnath Reddy, Vladislav V. Kharton, José M.F. Ferreira, Journal of Power Sources, 242, 486-502 (2013)S.-B. Sohn, S.-Y. Choi, G.-H. Kim, H.-S. Song, G.-D. Kim, Stable sealing glass for planar solid oxide fuel cell, J. Non. Cryst. Solids. 297 (2002) 103–112. doi:10.1016/S0022-3093(01)01042-0 Figure 1

Assessing the health risks of dermal exposure to heavy metals dust among nail salon technicians.

Nail salon technicians are susceptible to potential exposure to a diverse array of hazardous chemicals in the form of dust or vapors. One of the main routes of exposure is dermal contact. The aim of present study was to health risk assessment of dermal exposure to dust containing heavy metals in nail salon technicians. Dust sampling was done on the work surface of 20 available nail salon technicians. The concentration of five metals including cadmium, lead, chromium, nickel, and manganese were determined using ICP-MS. Afterwards, the United States Environmental Protection Agency (USEPA) guideline was used to estimate the potential health risks, including carcinogenic and non-carcinogenic risks, associated with the analyzed metals. Results indicated the mean concentrations of Pb, Cd, Ni, Cr and Mn were 0.7953±0.4373, 0.0952±0.0264, 0.7666±0.8629, 0.4900±0.5994 and 1.134±0.4736, respectively. The hazard quotient (HQ) of all metals was within the permissible value, while hazard index (HI) was greater than 1. The probability of cancer risk (CR) resulting from dermal exposure to Ni, Cd and Cr exceeded the acceptable risk levels (10-6-10-4), but CR calculated for Pb was less than allowable value. Implementation of engineering controls such as downdraft vented nail tables and portable source capture systems is necessary. Besides, the use of personal protective equipment such as disposable nitrile gloves, N95 respirator masks, and ensuring proper training on safe work practices is recommended.

Simulations With Compressible Multiphase Formulation on Heat Transfer Studies in a Rocket Thrust Chamber With Experimental Validation

Abstract In the combustor for rocket engines, liquid film cooling is a widely adopted technique for restricting the structural components to the acceptable bounds for the successful operation of the propulsion systems. Multiple cooling techniques for thrust chamber walls are favored along with the coolant film in propulsion systems operating at higher chamber pressures by incorporating an ablative cooling mechanism for the nozzle. The adoption of combination will result in challenges in simulation studies due to the presence of multiphase phenomenon in the system. The current article presents the effects of these two cooling methods on a thrust chamber wall studied through compressible multiphase formulations. A majority of the previous studies have used incompressible flow equations to model coolant film behavior and associated heat transfer. The present study utilizes an approach utilizing compressible multiphase flow to simulate the behavior of the compressible hot gas flow and the incompressible coolant liquid film accounting for phase change effects, vapor diffusion into hot gas, radiation effects on coolant surface, liquid entrainment, and blowing effects due to vapor formation at interface. Film-cooling effects on ablative nozzle accounting for pyrolysis phenomenon due to material decomposition governed by Arrhenius expression are also emphasized. The outcome of the numerical model showed good agreement with available test data in literature, and results from the tests done in-house. The model described in the present study was able to support the actual evidence of liquid film cooling being able to preserve the walls of the thrust chamber from severe internal thermal environment and prevent ablation on surface of nozzle.

Design and evaluation of composite films for in situ synthesis and antibacterial activity of allicin vapour

Although allicin has potent antibiotic properties, its low stability, which is responsible for its persistent biological activity, has posed a significant challenge to its practical application in modern medicine. To harness the healing benefits of this phytochemical, known by humans for thousands of years, we propose a controlled in situ synthesis of allicin vapour near the site of infection. Considering the critical need for novel approaches to prevent pandemic scenarios caused by MDR bacteria, we suggest encapsulating and physically separating allicin precursors (substrate alliin and enzyme alliinase) in alginate-based films and spray-dried chitosan microparticles. The mechanical properties of the hydrogel films of various compositions were evaluated, as well as their ability to protect the encapsulated alliinase against thermal stress and control the overall rate of allicin release upon hydration. Furthermore, the non-contact antibacterial efficacy of free alliin/alliinase reaction mixture (aqueous solution) and three compartmentalised configurations, i.e. film-solution, film-particles, and double-film, were tested against selected bacterial strains, i.e. E. coli, S. epidermidis, and S. aureus. The results indicate that the formation of allicin vapour using the proposed compartmentalised systems addresses allicin’s stability issues and provides better control over the rate of allicin production. The observed antibacterial effect was comparable with directly formed allicin using higher initial amounts of both substances, which is given by diffusion limitations associated with encapsulation. These findings illustrate the potential of compartmentalised systems in developing nature-based wound dressings for infection prevention and promoting healing.

Energy and exergy analysis of dry and steam external reformers for a power cycle based on biogas-fueled solid oxide fuel cell

In the present research a cogeneration cycle based on a solid oxide fuel cell (SOFC), and Organic Rankine Cycle (ORC) is proposed. The cycle is fed with biogas in different molar ratios of carbon dioxide to methane (RCTC). In addition, the cycle is examined for both dry reforming (DR) and steam reforming (SR). A thermochemical model is presented for both cycles of SR–SOFC–ORC, and DR–SOFC–ORC. The model is coded in MATLAB coupled with Engineering Equation Solver software. The model was verified with both experimental and theoretical research and agreement was achieved. The energy and exergy performance of the cycle is presented and carbon deposition on the cathode due to different reactions of methane cracking, Boudouard reaction, and vapor formation are studied. The results show that for RCTC<1.2 steam reforming produces more hydrogen, while for RCTC>1.2 dry reforming is advantageous. At RCTC = 1.2 the DR and SR work the same. The overall thermal efficiency of DR-SOFC and SR-SOFC has reached 67 % and 70 %. Carbon deposition due to the Boudouard reaction, and vapor formation for both SR and DR are negligible while due to methane cracking is serious. The DR-SOFC deposits less carbon because of methane cracking due to higher operating temperatures.

Determination of Capsaicinoids in Air Using Colorimetric Detectors

The significant physiological effect of capsaicinoids on the human body is utilized in the fields of food industry, medicine, and internal state security (riot control agents, RCAs). Detection and determination of capsaicinoids in solutions and extracts are fairly well developed, but only marginal attention is given to their detection in the form of aerosols and vapors, which are the primary form of their use as RCAs. In the article, three variants of a simple tube detector for direct detection of capsaicinoids in air (using pelargonic acid vanillylamide – PAVA, as the standard) are presented, utilizing classical color reactions with Turnbull’s blue, Gibbs reagent, and Marquis reagent. The use of these reactions for these purposes is innovative. Each reaction has been optimized and the proposed detectors have been compared, emphasizing their sensitivity, selectivity, and stability. PAVA in the air at a concentration of 0.1 mg/m3 can be detected with the naked eye. The stability of the proposed detectors allows for their commercial use.

Agarics-derived porous Fe/C material activated by ZnCl2 and its enhanced microwave absorption performance

Biomass-derived carbon materials retain the unique porous structure of biological raw materials and have environmental advantages, making them a popular choice for electromagnetic microwave absorption research. The microwave absorption performance of biomass-derived carbon materials is largely influenced by their pore structure, which can be controlled by chemical activators. In this study, ZnCl2 was chosen as the activator and de-impregnated agarics with Fe(NO3)3·9 H2O for pretreatment. The Fe(NO3)3·9 H2O can provide magnetic Fe particles for the material to enhance the magnetic loss ability. And the weakly acidic ZnCl2 can avoid the pollution of the environment, and its dehydration and dehydroxylation properties can release the hydrogen and oxygen in the biomass char material in the form of water vapor, and release the hydrogen and oxygen in the biomass carbon material in the form of water vapor, and form a porous structure. porous structure. In addition, ZnCl2 will be converted to ZnO during the activation process, and the removal of ZnO by acid washing will increase the internal pore volume, form a conductive network, and form a rich three-dimensional interconnected pore structure. The pretreated samples were vacuum carbonized at high temperature to obtain agarics-derived porous Fe/C material, which is an excellent lightweight and high-performance microwave absorbing material. The resulting material has a wider absorption bandwidth and improved microwave absorption performance. At a thickness of 2.55 mm and a frequency of 8.31 GHz, the RLmin of Fe/C material is −51.14 dB. Furthermore, at a thickness of 2.13 mm, it has an effective absorption bandwidth of 3.63 GHz, covering most of the X-band.