Thermal Process Research Articles

Light-Operated Diverse Logic Gates Enabled by Modulating Time-Dependent Fluorescence of Dissipative Self-Assemblies.

Light-fueled dissipative self-assembly possesses enormous potential in the field of optical information due to controllable time-dependent optical signals, but remains a great challenge for constructing intelligent light-operated logic circuits due to the limited availability of optical signal inputs and outputs. Herein, a series of light-fueled dissipative self-assembly systems with variable optical signals are reported to realize diverse logic gates by modulating time-dependent fluorescence variations of the loaded fluorophores. Three kinds of alkyl trimethylammonium homologs are employed to co-assemble with a merocyanine-based photoinduced amphiphile separately to construct a series of dissipative self-assemblies, showing unexpectedly different fluorescence control behaviors of loaded fluorophores during light irradiation and thermal relaxation processes. The opposite monotonicity of time-dependent emission intensity is achieved just by changing the excitation wavelength. Furthermore, by varying the types of trimethylammoniums and excitation wavelengths, a robust logic system is accomplished, integrating AND, XNOR, and XOR functions, which provides an effective pathway for advancing information transmission applications.

Machine learning force field for thermal oxidation of silicon.

Looking back at seven decades of highly extensive application in the semiconductor industry, silicon and its native oxide SiO2 are still at the heart of several technological developments. Recently, the fabrication of ultra-thin oxide layers has become essential for keeping up with trends in the down-scaling of nanoelectronic devices and for the realization of novel device technologies. With this comes a need for better understanding of the atomic configuration at the Si/SiO2 interface. Classical force fields offer flexible application and relatively low computational costs, however, suffer from limited accuracy. Ab initio methods give much better results but are extremely costly. Machine learning force fields (MLFF) offer the possibility to combine the benefits of both worlds. We train a MLFF for the simulation of the dry thermal oxidation process of a Si substrate. The training data are generated by density functional theory calculations. The obtained structures are in line with abinitio simulations and with experimental observations. Compared to a classical force field, the most recent reactive force field, the resulting configurations are vastly improved. Our potential is publicly available in an open-access repository.

Amorphous to Crystalline Transition in Nanoimprinted Sol-Gel Titanium Oxide Metasurfaces.

Crystalline titanium dioxide (TiO2) (anatase and rutile) possesses a higher refractive index than amorphous TiO2 and near-zero absorption in the visible region, making them an ideal material for visible metasurfaces. However, fabrication limitations hinder their implementation into flat optics. In this work, a wafer-scale manufacturing platform is proposed for crystalline TiO2 metasurfaces. Sol-gel TiO2 is developed as a printable material in which its material phase can be precisely controlled to produce amorphous, anatase, or rutile, depending on the crystallization temperature. Therefore, anatase or rutile metalenses can be fabricated on a wafer scale using thermal nanoimprint lithography and sintering process. The high refractive index of the crystalline TiO2 contributes to the enhanced conversion efficiency of the fabricated metalenses. The fabricated metalenses exhibit diffraction-limited focusing and imaging capabilities, comparable to the theoretically ideal lenses.

Evaluation of Boundary Layer Characteristics at Mount Si’e Based on UAV and Lidar Data

The atmospheric boundary layer is a crucial transitional region connecting the surface with the free atmosphere, playing a bridging role in land-sea-air interactions and the interactions between different atmospheric layers. This study utilizes rotary-wing UAVs, high-resolution lidar, and WRF simulation data to analyze the vertical distribution characteristics of temperature, humidity, wind speed, and wind direction boundary layer over the Mount Si’e region in 4–6 April 2024. The results indicate that the boundary layer temperature decreases with increasing altitude, reaching up to 18°C, while humidity decreases with height, dropping to as low as 35%. Daytime wind speeds range from 4 to 8 m/s, decreasing to 2 to 4 m/s at night. The boundary layer height can reach up to 900 m during the day and drops to 100–200 m at night, showing distinct diurnal variation characteristics. UAV observations are in good agreement with lidar and WRF simulation results, highlighting the application value of UAVs in high temporal and spatial resolution boundary layer studies. The study also reveals the significant impact of complex terrain on boundary layer characteristics, providing scientific insights into the dynamic and thermal processes of the boundary layer and offering reference value for improving regional weather forecasting and numerical simulations.

New hot workability prediction method under non-constant deformation conditions

The deformation conditions of metallic materials constantly change during forming and manufacturing technology. The thermomechanical processing theory cannot be applied to non-constant deformation conditions. The hot workability is a manifestation of the deformation conditions that affect the microstructure. This paper proposes a new prediction method based on artificial intelligence, considering the combined effect of microstructure state and deformation conditions. The hot deformation experiments under constant and non-constant deformation conditions validate the proposed method. Dynamic variation in deformation conditions significantly affects the hot workability. The findings indicate that reasonable control of the dynamic variation in deformation conditions during thermomechanical processing is conducive to improving the hot workability, providing new ways for equipment upgrading and process parameter optimization of some thermal processing technologies.

Effect of initial quality of oil and thermal processing on oxidation indexes in canned tuna

The content of fatty acids and the ratio of unsaturated and saturated fatty acids are essential parameters for determining the nutritional value of oils. The main objective of this study was to identify the oxidation changes of three vegetable oils (soybean, sunflower, and olive oil) at two qualitative levels in the canned tuna product before and after the thermal process. The progress of oil oxidation was assessed by measuring peroxide value (PV), p-anisidine value (AV), malonaldehyde (MDA) content, Conjugated dienes (CDs), and conjugated trienes (CTs), p-anisidine value, total free acidity, INTOX and TOTOX values. The results indicated that the quality of oil extracted from canned fish changes according to the type of oil (p < 0.01). A decrease in the peroxide value during the thermal process (<2 meq O2/kg oil in olive and soybean oil), indicated that this parameter is not suitable for showing product quality and oxidation progress, lonely. Secondary products of oxidation, in soybean oil under sterilization caused an increase of p-anisidine value (149) but in olive and sunflower oil heating caused a rise of MDA content. Acidity value was an index that increased after heating all types of oil and all types of quality and seemed to be more reliable for determination of the quality of oil in canned tuna (p < 0.01).

Computer-aided design of thermosetting benzoxazoles containing bis-endoalkynyl groups: Low melting points and high thermal stability

High-temperature-resistant polybenzoxazoles (PBOs) have recently become a prominent research area due to their potential applications in aviation and aerospace. However, achieving a balance between thermal stability and processability remains a significant challenge. In this study, a computer-aided method to develop PBOs with high thermal stability and processability is explored. First, thermoset benzoxazoles (CPBOs) are designed using a material genomic approach. Subsequently, their zero shear viscosity, temperature at 50 % thermal weight loss, dielectric constant and dielectric loss are predicted using a computer-aided method. Finally, two screened thermosetting benzoxazoles, CPBO-1 and CPBO-6, are synthesized and experimentally validated. The experiments indicate that their melting points are below 100 °C, with the lowest melt viscosities being 0.5 Pa•s and 1.5 Pa•s, respectively. The corresponding polymers, pCPBO-1 and pCPBO-6, feature high thermal stability. The 5 % weight loss temperature of pCPBO-1 in N2 is 618.9 °C, while the dielectric constant and dielectric loss are 3.1 and 0.0063, respectively. These are excellent values for thermosetting resins. This computer-aided screening method is more efficient and cost-effective compared to conventional trial-and-error methods.

Sewage sludge thermal hydrolysis impact on the quality of biogas in anaerobic digestion process – siloxanes and VOCs studies

This paper presents the results of a study of biogas from the anaerobic digestion (AD) process of municipal sewage sludge (SS) under 43–48oC temperature conditions, using the example of a wastewater treatment plant (WWTP) in Tarnów (Poland). In the case in question, the AD of SS is preceded by a 165oC thermal hydrolysis process (THP) using Cambi THP® technology. The study of biogas concerned the basic parameters: temperature, relative humidity, content of CH4, CO2, O2, H2, N2, H2S, CO.Similar studies can be found in the literature, but they concern classical methane fermentation without considering the THP process. The present study comprehensively describes the relationship between the THP process and AD and the quality of biogas. The content of siloxanes and volatile organic compounds (VOCs) in biogas was also examined, including concentrations of Tetramethylsilane, Trimethylsilanol, L2, D3, L3, D4, L4, D5, D6, as well as toluene, benzene, xylenes and other VOCs. The results showed high concentrations of these compounds in raw biogas up to 42 mg/Nm3 in total siloxanes and 15.8 mg/Nm3 in total silicon, as well as the efficiency of biogas purification in an activated carbon filter with results of total siloxanes <0.31 mg/Nm3 and total silicon <0.11 mg/Nm3.

Study the impact of spacer at thermal degradation process of MLI-based insulation in fire condition

To reduce CO2 emissions, energy carriers such as hydrogen are considered to be a solution. Consumption of hydrogen as a fuel meets several limitations such as its low volumetric energy density in gas phase. To tackle this problem, storage as well as transportation in liquified phase is recommended. To be able to handle this component in liquid phase, an efficient thermal insulation e.g., MLI insulation is required. Different studies have been addressed the vulnerability of such insulation against high thermal loads e.g., in an accident engaging fire. Some of research works have highlighted the importance of considering the MLI thermal degradation focusing on its reflective layer. However, limited number of studies addressed the thermal degradation of spacer material and its effect on the overall heat flux.In this study, through systematic experimental measurements, the effect of thermal loads on glass fleece, glass paper as well as polyester spacers are investigated. The results are reported in various temperature and heat flux profiles. Interpreting the temperature profiles revealed that, as the number of spacers in the medium increases, the peak temperature detectable by the temperature sensor on the measurement plate decreases. Each individual spacer contributes to mitigating the radiative energy received by the measurement plate. Stacks of 20–50 spacers (this is the number of layers in commercial MLI systems applied for liquid hydrogen applications) can potentially reduce the thermal radiation by 1–2 orders of magnitude.An empirical correlation to predict a heat flux attenuation factor is proposed, which is useful for further numerical and analytical studies in the temperature range from ambient to 300 °C.

Facilely prepared extreme environments tolerable PIF /c-CNTx composites for piezoresistive sensor based on powder foaming strategy

Polyimide foams (PIF) are widely used in piezoresistive sensors due to their light weight and weather resistance to weathering at extreme temperatures. Nevertheless, the mechanical strength of PIF prepared by freeze-drying method is poor, with only tens to hundreds of kPa ranging from 50 % to 80 % compression. Herein, a polyimide composite reinforced with –COOH functionalized multi-walled carbon nanotubes (PIF/c-CNTx) was produced via a thermal foaming process using a powder-based method. The PIF/c-CNTx composites exhibit ultra-low density (0.165 g/cm3), excellent mechanical properties (compressive strength of up to 2.5 MPa at 60 % compressive strain, tens to hundreds of times higher than similar materials) as well as stable compressive properties and recoverability in liquid nitrogen and at high temperatures up to 200 ℃. The PIF/c-CNTx piezoresistive sensor achieves excellent sensing capability over a wide strain range, high sensitivity (GF = 12.9) and exhibit good stability over 5000 s of cyclic compression at a compression rate of 10 mm/min. The stability and reproducibility of the strong piezoresistive signal at extreme temperatures shows the great potential of PIF/c-CNTx composites as structural components under extreme conditions for applications in aerospace and polar exploration.

Open-loop temperature rise history control method with scanning electron beam as a programmable heat source

Temperature-rise history control technology is widely applied in rapid thermal process and material thermal assessment. We present an open-loop temperature rise history control method. The fundamental concept involves loading a heat flux history onto the sample’s surface, inversed from the target temperature rise history, to regulate the sample’s temperature through programming the energy flux history of the scanning electron beam. We reconstructed the temperature-rise history of the leading edge of an aircraft during the HIFIRE-5b flight test with a relative deviation of 1%. Additionally, we reconstructed a typical temperature rise curve of a silicon wafer during rapid thermal processing with a relative deviation of 1%. In theory, this temperature control method can be extended to two-dimensional and three-dimensional heat transfer processes to achieve transient control of sample surface/cross-section temperature field with one- or two-dimensional distribution characteristics. This research can provide a high-performance temperature control technology for a wide range of industrial fields, and lay a theoretical foundation for the development of related technologies based on temperature history analysis.

Challenges in the Valorization of Green Waste in the Central European Region: Case Study of Warsaw

Expanding green areas in cities results in growth in green waste generation. This study presents the findings of an investigation into green waste from selective collection in a large Central European city (Warsaw, Poland), which can be identified as a valuable biomass resource. The research objective was to identify the properties of garden waste from single-family housing to determine valorization opportunities, emphasizing the utilization of GW as a source of energy. The research yielded several findings, including a notable degree of variability in fuel properties, including moisture content (CV = 30%), lower heating value (CV = 14.3%), and ash content (CV = 62.7/56.2%). The moisture content suggests composting, while the fertilizing properties indicate suitability for anaerobic digestion. The instability of the fuel properties, coupled with the elevated levels of chlorine, sulfur, and moisture, constrains the use of garden waste in thermal processes and alternative fuel production. Pyrolysis could be a viable approach for green waste feedstock, offering value-added products depending on the processing conditions and pre-treatment. Nevertheless, implementing a selective collection system is a critical condition for the optimal utilization of bio-waste, facilitating the quality and property control of green and food waste. This is essential for their effective processing, including energy recovery, thereby contributing to the efficient valorization of biomass.

Numerical evaluation of ground source heat pumps in a thawing permafrost region

Permafrost degradation poses significant environmental and geological challenges in Arctic and subarctic regions, particularly in areas like Umiujaq, Canada. The warming climate leads to thawing permafrost, causing ground instability, disrupting hydrology, and impacting local built environment. This study evaluates the use of Ground Source Heat Pump (GSHP) operation for mitigating ground subsidence in a permafrost region using a two-dimensional Thermo-Hydro-Mechanical (THM) coupled finite element analysis considering the ground poro-elastic and poro-plastic responses. The research uses a single-well scenario to demonstrate the interactions among thermal, hydraulic, and mechanical processes. The impact of GSHP operation under different temperature management strategies, including a scenario with a constant GSHP temperature of −5 °C throughout the year is numerically investigated. Results indicate that GSHP operation exacerbates ground deformation near the borehole, particularly during winter months. However, maintaining GSHP operation throughout the entire year can mitigate extreme subsidence fluctuations, leading to a more stable subsurface environment. While GSHP systems provide effective thermal regulation, their operation can introduce mechanical stresses that potentially disturb the ground close to the borehole. Therefore, careful design, operation, and further research are essential to balance thermal benefits with ground stability in permafrost regions.

On the thermal performance of a three-dimensional cross-ternary hybrid nanofluid over a wedge using a Bayesian regularization neural network approach

Abstract Significance Studying the flow of ternary nanofluids [Ag, Cu, MoS2] holds significant importance in both science and engineering. Ternary nanofluids are vital in advancing thermal management systems, heat exchangers, aerospace, and materials processing applications. Purpose This study investigates the ternary hybrid Carreau nanofluid numerically for thermal proficiency in the inclined magnetized environment. In this study, three distinct nanoparticles of [Ag, Cu, MoS2] and base fluid water over the wedge are used. The velocity of nanofluids is judged under the influence of an inclined magnetic field, and the thermal performance is scrutinized by incorporating the thermal radiation effect. Methodology The physical problem generates partial differential equations, which are transformed into ordinary differential equations (ODEs) through similarity variables. These ODEs are linearized into a system of ODEs and then passed under the bvp4c Matlab program to get the solution. This solution is again trained by an artificial neural network, and further results are obtained with both schemes and compared. Findings The most rapid heat transport analysis is found for ternary hybrid nanofluids compared to bi-hybrid nanofluids. The thermal radiation parameters and the magnetic environment augment the rate of heat transport.

Analysing the influence of temperature dependence of active resistances on transmitted power in electric power systems

Subject of research: in this paper, the static stability of electric power systems is assessed taking into account the temperature dependence of active resistances. Purpose of research: to show how the consideration of the temperature dependence of active resistances will affect the static stability reserves of electric power systems. Methods and objects of research: calculations of the regime with account of influence of thermal processes in elements of power system are made. The main parameter to take into account thermal processes is the ambient air temperature, so the days with maximum and minimum average daily air temperature were determined. All parameters except ambient air temperature and wind speed were selected in such a way as to provide the worst conditions for thermal exchange. The results of the calculations show that taking into account the thermal processes in the elements of the system significantly affects the transmitted power and the reserves of static aperiodic stability in the power system. Main results of research: practical calculations have shown that the account of thermal processes allows to take into account more accurately the limits of the transmitted power through the elements of the power system, and at the same time the reserve coefficients of static stability.

Role of dislocation behavior during aging in high-temperature microstructural evolution and creep property of single crystal superalloys

Single-crystal superalloys of turbine blades suffer unexpected performance deterioration, even when manufactured with optimal γ/γ′ phase morphology. This study successfully reproduced this abnormal decrease in high-temperature creep properties by applying optimal aging treatments to a skillfully designed model single-crystal superalloy. Microstructural evidence indicates that interfacial dislocations deposited during aging processes weaken dislocation distribution anisotropy (DDA) in the steady creep stage and place γ′-topological inversion ahead of the competition between γ′-rafting and it, leading to an increase in the minimum creep rate. Through constitutive equations and inductive research, a linear negative correlation between the minimum creep rate and DDA was established. A new concept of “phase-interface freshness” is proposed as a quantitative characterization of interfacial dislocation deposition after preparation to reflect the ability to stimulate the beneficial DDA. These results help us further understand thermal processes such as aging, coating, and welding, providing theoretical support for the design and optimization of thermal processes.

Improved preservation of the color and bioactive compounds in strawberry pulp dried under UV-Blue blocked solar radiation

Strawberry (Fragaria ananassa spp.) is a highly preferred fruit because of its health benefits, flavor, fragrance, and color appeal. The drying process for strawberries extends their shelf life but also changes their color and alters their nutritional contents. The anthocyanins are responsible for the color, which are susceptible to degradation during thermal processing, reducing the customer appeal of these food products. The benefit of solar drying of strawberry pulp using UV-Blue blocking optical filters compared with d irect solar drying is presented in this work. Total anthocyanins, antioxidant activity, and the color of the strawberry pulp were monitored as the drying progressed. The UV-Blue blocking optical filter consisted of a copper sulfide/copper selenide thin film of 160 nm in thickness applied on the outer surface of cellular polycarbonate sheets of 8 mm cell-size, 0.1 mm wall thickness (1 kg/m2) cut from sheets measuring 122 cm x 122 cm in area, and protected by a food-safe adhesive polyethylene foil. Total anthocyanins and antioxidant activity were measured using the differential pH and the DPPH (2,2-diphenyl-1-picrilhydrazil) methods. The filter preserves a higher total anthocyanin content and antioxidant activity in the dried product than in the pulp dried under sunlight conditions. A reduced total color change was observed in the product dried under the UV-Blue blocking solar filter. This study highlights a general need to evaluate the bioactive merits of solar dried farm produce to assess the advantage they hold for their commercialization.

Origin and preservation mechanisms of organic matter in carbonate concretions from Lower Cambrian black shales in South China

Carbonate concretions are widely used in paleoclimate, paleoenvironmental, and paleontological studies, and even in the study of potential life on Mars. These petrological, elemental, isotopic, and lipid biomarker signals in Meso-Cenozoic carbonate concretions (relatively low thermal maturity) can effectively preserve details of seawater conditions and benthic ecosystems during the deposition of their host sediments/rocks. However, such research on Precambrian-Cambrian carbonate concretions under highly mature conditions remains scarce, and the ability of these ancient carbonate concretions to retain their original biogenic information remains uncertain. To achieve that, this study examines two Cambrian carbonate concretions, using samples from the center, transition, and rim of each, and their adjacent host black shales from the Lower Cambrian Qiongzhusi Formation in the Yangtze Block, South China. Organic and inorganic geochemical analyses were combined to elucidate the origin and preservation process of organic matter (OM) in these ancient Cambrian carbonate concretions. The results show that the thermal maturity of OM within these concretions (1.8 % EqVRo) is relatively low compared to their adjacent host shales (2.9 % EqVRo). Hopanes and steranes are detectable in both free and calcite-occluded hydrocarbons within these concretions, with concentrations of individual compounds ranging from 0.001 to 0.800 μg/g TOC, whereas kerogen-bound hydrocarbons lack detectable biomarkers. The results indicate that the two Cambrian carbonate concretions were formed mainly within the iron reduction and bacterial sulfate reduction zones, extending to depths of 10 to 38 m below the sediment-water interface. The OM within these concretions mainly inherited the initial unaltered signature of OM from the Qiongzhusi host shale. The carbonate concretions protected the internal OM from further thermal and secondary (e.g., biodegradation) alteration processes and might also prevent the formation of the conventional macromolecular skeletal kerogen manifested by the absence of bound biomarkers. The biomarkers, in both free and occluded forms, in the Cambrian carbonate concretions still retained their original source information, providing valuable insights into ancient biogeochemical processes during sediment burial and ancient seawater chemistry during the early Cambrian.

Correlation of Processing and Structure in an Ethylene-Glycol Side-Chain Modified Polythiophene via Combined X-Ray Scattering and 4D Scanning Transmission Electron Microscopy.

The results of a combined grazing incidence wide-angle X-ray scattering (GIWAXS) and 4D scanning transmission microscopy (4D-STEM) analysis of the effects of thermal processing on poly(3[2-(2-methoxyethoxy)ethoxy]-methylthiophene-2,5-diyl) are reported, a conjugated semiconducting polymer used as the active layer in organic electrochemical transistor devices. GIWAXS provides a measure of overall crystallinity in the film, while 4D-STEM produces real-space maps of the morphology and orientation of individual crystallites along with their spatial extent and distribution. The sensitivity of the 4D-STEM detector allows for collection of electron diffraction patterns at each position in an image scan while limiting the imparted electron dose to below the damage threshold. The effects of heat treatment on the distribution and type of crystallites present in the films isdetermined.

Isolation and characterization of a novel phage P785, its combination with thermal processing for the biocontrol of Escherichia coli in milk

Isolation and characterization of a novel phage P785, its combination with thermal processing for the biocontrol of <i>Escherichia coli</i> in milk