Effect Of Thermal Treatment Research Articles

A study on the effects of thermal treatments and gamma rays irradiation on expired “Helixone” membranes

A study on the effects of thermal treatments and gamma rays irradiation on expired “Helixone” membranes

Core–shell nanofibers as carrier systems for sustained delivery of tea tree oil

Tea tree ( Melaleuca alternifolia) oil is a plant-derived essential oil with broad-spectrum antimicrobial activity. In this study, tea tree oil, a volatile essential oil, was encapsulated into a polymeric matrix by emulsion electrospinning to prepare core–shell nanofibers and investigate composite nanofibrous membranes as potential delivery vehicles of the antimicrobial agent. Poly(vinyl alcohol) (PVA), which is a biodegradable polymer used as a medical material, was combined with tea tree oil for pharmaceutical and medical applications. Composite PVA nanofibers with a well-aligned core–shell structure containing tea tree oil were obtained via electrospinning from an emulsion comprising the oil and an aqueous PVA solution. Thermal treatment was used to make the PVA-based nanofibrous membranes stable in moist environments. The effects of drying and thermal treatment on the release behavior of tea tree oil from the composite membranes were thoroughly investigated. The antimicrobial effects of tea tree oil embedded in nanofibrous membranes were assessed against Propionibacterium acnes and Staphylococcus aureus. Although the thermal treatment of the PVA nanofibers loaded with tea tree oil reduced the emission of volatile organic compounds, terpinen-4-ol, an active antibacterial component of the oil, was released continuously over 14 days. The composite membranes containing tea tree oil presented strong antibacterial effects against Propionibacterium acnes and Staphylococcus aureus. Thus, these bioactive nanofibrous membranes show promise as potential carrier systems for tea tree oil, which represses microbial growth, and may be used for topical skin infection treatment.

Estimated effectiveness of treatments against salmon lice in marine salmonid farming

We here estimate the effectiveness of ten types of salmon lice treatments currently used in the salmonid industry by analysing daily and cage-wise data from 90 full production cycles from farms spread along the Norwegian coast. The calculations are based on a stage-structured population model for salmon lice and accounts for the structure of the data, including the uncertainties that arise from the weekly counting of lice on a subset of the fish. Results suggest that the most commonly used treatment methods in the data set, i.e. thermal, mechanical and freshwater treatments, kill 70–80% of the lice in average, but with high variability. Feed treatments with emamectin benzoate are also commonly used, but are only estimated to kill around 35% of the lice in average. Bath treatments with hydrogen peroxide are estimated to kill around 74% and pyrethroids 50% of the lice in average. The other medicinal treatments were infrequently used in the data set and the estimates are therefore more uncertain. Of note is that the recently licenced bath treatment with imidacloprid is estimated to kill more than 99% of sessile and 98% of pre-adult and adult lice in average. The estimated effects of hydrogen peroxide, pyrethroids and azamethiphos, here based on data from 2017–2020, are lower than estimates from a previous analysis of production data from 2011–2014, possibly because of resistance development. In contrast, there is no indication of reduced effects of thermal, mechanical or freshwater treatments compared to previous analyses of production data from 2013–2018. These results allow comparing the effectiveness of the different treatment methods in a consistent and comprehensive way, hence enabling fish farmers and authorities to better balance the expected benefits of the treatments in terms of lice control against the economic costs, fish welfare and risk of resistance development.

Study on anaerobic fermentation of waste activated sludge to produce volatile fatty acids by thermal–rhamnolipid treatment

AbstractBACKGROUNDThe extracellular polymer and cell wall of waste activated sludge serve as chemical barriers for anaerobic fermentation, limiting the recycling and utilization of organic carbon contained in the sludge. To improve the efficiency of anaerobic fermentation, this paper proposes thermal–rhamnolipid (T‐RL) pretreatment technology and systematically discusses the effect of T‐RL treatment on the anaerobic fermentation of waste activated sludge for acid production from the perspective of organic matter dissolution characteristics, total volatile fatty acid (VFA) content, composition and microbial changes.RESULTST‐RL treatment significantly promoted the dissolution of organic matter in sludge, with soluble chemical oxygen demand solubilizing to 6097.78–7375.56 mg L−1, soluble carbohydrates solubilizing to 207.38–274.74 mg L−1, and the dissolution of soluble proteins and DNA also at a high level. Both treatment factors significantly promoted the enrichment of acid‐producing microorganisms, especially acetic acid‐producing microorganisms. The best VFA production conditions of T‐RL treatment were 60 mg g−1 total solids and 70 °C, and the yield was 3294.96 mg L−1. Compared with thermal and RL treatments, the optimum yield of T‐RL treatment increased by 33.16% and 22.06%, respectively. The VFA components in the T‐RL group were mainly acetic acid and propionic acid. Under optimal conditions, the proportion of acetic acid and propionic acid reached 77%.CONCLUSIONT‐RL treatment can promote sludge disintegration and organic matter conversion through the coupling effect of thermal and RL treatments, providing sufficient and high‐quality substrate for acid‐producing microorganisms, effectively enriching VFA producers, and thus improving the efficiency of anaerobic fermentation for VFA production. This treatment technology will provide some beneficial references for the future utilization of sludge resources. © 2023 Society of Chemical Industry (SCI).

Combination of Thermal-Treated Kelulut (Stingless Bee) Honey and Phyllanthus niruri Extract: Evaluation on Antibacterial Activity Against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis

Kelulut honey (KH) has a broad spectrum of antibacterial effects that conceivably deteriorate upon heat treatment. However, further synergistic combinations with plant extract might be of value in improving the bactericidal capacity. Therefore, this study reports on the combination of KH with Phyllanthus niruri extract as both are independently known to be bactericidal. P.niruri extract was incorporated into 2 types of KH; untreated and thermal-treated (50, 60 and 70 °C for 5, 10, 15 and 30 min); and tested against 4 bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis) through disc diffusion method. Untreated KH in general had a bigger inhibition zone than thermal-treated. The inhibition reaction was considered sensitive (> 8 mm) against S.aureus, E.coli and P.aeruginosa. Whereas, the effect of thermal treatment on KH was significantly (p < 0.05) apparent against S.aureus, in which the inhibition zones were mostly not sensitive (< 8 mm). In combination, the mixture of 70:30 (KH:P.niruri) had the highest inhibition zone as compared to other ratios. However, the interaction was only deemed to be synergistic with untreated KH, principally against S.aures and P.aeruginosa. The results thus showed the vast inhibition spectrum of KH as affected by thermal treatment and combination with P.niruri extract. Thermal treatment reduced the bactericidal of KH while incorporation with P.niruri extract could synergistically improve the bactericidal with a ratio of 70:30. HIGHLIGHTS Untreated Kelulut honey (KH) demonstrated antibacterial activity against bacterial strains tested Thermal treatment reduced the antibacterial activity of KH Combination with niruri extract showed an increment in antibacterial activity A Synergistic combination was attained with the ratio of 70:30 (v/v) of KH:niruri extract GRAPHICAL ABSTRACT

Effect of thermal treatments on volatile profiles and fatty acid composition in sweet corn (Zea mays L.).

This study analyzed the effects of thermal processing on volatiles and fatty acids in sweet corn. There were 27 volatiles measured in fresh samples, and 33, 21, and 19 volatiles identified in the steaming, blanching, and roasting groups, respectively. Relative odor activity values (ROAVs) showed that characteristic aroma-active volatiles of sweet corn after thermal treatments included: (E)-2-nonenal, 1-octen-3-ol, beta-myrcene, dimethyl trisulfide, 1-(4,5-dihydro-2-thiazolyl)-ethanone, and d-limonene. Thermal treatments significantly increased the unsaturated fatty acids (oleic acid and linolenic acid) of sweet corn by 110 to 183% compared to fresh samples. Meanwhile, many characteristic volatiles were found that derived from the oxidative cleavage of fatty acids. The sweet corn aroma obtained by steaming for 5min was considered the closest to fresh corn. Our research provided insight into aroma composition of different thermally processed sweet corn and laid the foundation for further exploring the sources of aroma compounds in thermally processed sweet corn.

The Effect of Thermal Treatment on Weld Structure of the VZh178P Alloy after Rotational Friction Welding

The Effect of Thermal Treatment on Weld Structure of the VZh178P Alloy after Rotational Friction Welding

Effect of thermal treatment on the 4f-hopping conductivity of CeO2 exposed to CO(g) atmosphere

Effect of thermal treatment on the 4f-hopping conductivity of CeO2 exposed to CO(g) atmosphere

The effect of thermal treatment on antioxidant activity and changes in bioactive and phenolic compounds of three pear (Pyrus spp.) varieties slices

In this research, the effect of dehydration on total phenolic amounts, total flavonoid, total carotenoid, antioxidant activity values of pear cultivars (Santamaria, Margerit, and Deveci) dried by hot-air (oven) at 50 and 90 °C temperatures was investigated. The moisture contents of control groups of pear fruits were found between 79.12% (Deveci) and 83.39% (Santamaria). The moisture contents of pear samples dehydrated at 50 and 90°C changed between 8.39 (Santamaria) and 12.11% (Deveci) to 8.27 (Santamaria) and 14.17% (Deveci), respectively. The phenolic results of pear varieties for control groups were determined between 3.33 (Deveci and 38.43 GAE/100 g (Margarit). Total phenolic contents of pear fruits dried at 50 and 90 °C varied between 73.98 mgGAE/ 100 g Deveci) and 114.81 mgGAE/100 g (Santamaria) to 148.89 mg/100 g (Deveci) and 176.48 mgGAE/ 100 g (Margarit), respectively. In addition, total flavonoid contents of pear samples dried at 50 and 90 °C changed between 99.56 mg/100 g (Deveci) and 229.56 mg/100 g (Santamaria) to 254.00 (Deveci) and 392.89 mg/100 g (Santamaria), respectively. While antioxidant activities of pears dried at 50 °C change between 30.44% (Deveci) and 44.90% (Santamaria), the antioxidant activities of pears dried at 90 °C were determined between 60.52% (Deveci) and 67.47% (Santamaria). Results obtained exhibited some fluctuations depending on drying temperatures compared to the control.

Effect of Thermal Treatment on Morphology and Acetone Gas Sensing Properties of Fe3O4-C Nanocomposites Prepared via Green Synthesis

Fe3O4-C nanostructured composites were used for the fabrication of thin films as active layers in resistive chemical sensors. Nearly spherical and porous structures were obtained via green method using olive leaf extract (OLE) followed by thermal process at 300 °C and 550 °C, respectively, for high-performance gas sensing applications. The prepared sensors were measured with various concentrations of toxic gases such as acetone (C3H6O), ethanol (C2H5OH), and carbon dioxide (CO2) at different operating temperatures. The gas sensing results illustrated that the porous structure of Fe3O4-C nanocomposite exhibited high response of 15.71, 225.35 and 3141.66 toward 20, 100 and 1000 ppm of acetone gas at 300 °C. The sensor based on porous structure of Fe3O4-C nanocomposite also indicated fast response and recovery time as well as higher response to acetone compared to ethanol and CO2 gases. The better gas-sensing properties of the porous nanostructures can be attributed to the higher surface area of porous compared with the nearly spherical structure which is confirmed using BET analysis. The gas sensing performance of porous Fe3O4-C nanocomposite reveals that it can be a good sensing material for the fabrication of acetone gas sensors.

Reversibility and thermal dependence of the martensitic transformation in a melt-spun Ni55Fe17Ga26Co2 Heusler alloy

An almost single phase 14 M modulated martensite is obtained in melt spun ribbon of Ni55Fe17Ga26Co2 Heusler alloy. The effect of thermal treatments on the stability of the reverse martensitic transformation from 14 M modulated martensite to austenite phase in this system has been investigated by both non-isothermal and isothermal treatments. Heating above martensitic transformation promotes a continuous reduction of the martensitic transformation temperature, which stabilizes the austenite phase at room temperature and induces the precipitation of the gamma phase. However, thermal treatments at temperatures between the austenite start and finish temperatures induce the decoupling of the austenite formation in a subsequent heating. The two successive reverse martensitic transformations could be ascribed to the untransformed martensite in the previous interrupted heating and to the new martensite formed during cooling.

Increasing the Reliability of Aluminum Wirebonds by Thermal Treatments: Analysis and Implementation

In this work we studied the effect of a post-bonding thermal treatment on thick aluminum wirebonds lifetime in IGBT power modules during power cycling at different temperature swings. A reliability improvement of up to 44% is demonstrated for the bonds located at the center of the chip and seeing the highest thermal treatment temperature. The physical phenomena occurring during the thermal treatments and during power cycling are studied using microstructure analysis (Scanning Electron Microscopy techniques) and nanoindentation. Softening of the material results from recrystallization and/or recovery during thermal treatment, whereas during power cycling the thermal treated material hardens due to strain accumulation and defect formation. Despite the hardening our data suggests a decrease in crack growth rate at the second half of the testing time. We implemented an approach for applying thermal treatments during typical operating conditions in a converter by controlling the off-state losses of a device in a multichip configuration. The stability and the limits of this approach are studied experimentally and described by an electrothermal model. This study allows us to conclude on a realistic process window for online thermal treatments, by considering both material constrains and practical temperature control limits.

Investigating the effects of SiC particles addition and thermal treatment on 90% Al- 10% Cu alloy

Investigation of the effects of SiC particles addition and thermal treatment on 90Al-10Cu alloy has been undertaken. The work produced 90Al-10Cu Alloy and further produced test castings to which particle additions of SiC were added in the order 0.5%SiC, 1%SiC, 2%SiC and 4%SiC to see the effects of a wider variation in particle addition. These additions were made using stir-cast method to produce the test sample bars. The test sample bars were then taken to the University of Uyo, Faculty of Engineering workshop to prepare the test specimens into standard specifications for various tests. Some of the prepared test specimens were then given thermal treatment called age hardening. The specimens were first solutionised in the furnace at 500 oC (500 C) and quenched in warm water at 60C. It was then aged at 170C for three hours before cooling in air. It was after this treatment that the test specimens were subjected to hardness test, wear resistance test, strength test, and microstructure analysis. The result of the work showed that the thermal treatment had effect on the microstructure of all the samples. The result also showed that the SiC particle addition also affected the mechanical properties of the specimens. For the untreated compositions the alloy and 90Al-10Cu/2%SiC particulate composite had the lowest wear rate value of 0.0212mm3/N/m. 90Al-10Cu/1% SiC had the highest hardness value of 67.38 BHN. 90Al-10Cu/0.5%SiC particulate composite outperformed other compositions with the following mechanical properties: hardness value of 64.28BHN; ultimate compression strength of 217.18N/mm2; % reduction at failure of 3.01; and wear rate value of 0.0633 mm3/N/m. For the thermally treated compositions; the lowest wear rate of 0.0246mm3/N/m is with the alloy composition and 90Al-10Cu/2%SiC particulate composite. 90Al-10Cu/1%SiC particulate composite has the highest hardness value of 82.02BHN; the highest % reduction at failure of 1.13%, and wear rate value of 0.05982, while 90Al-10Cu/0.5%SiC particulate composite has hardness value of 80.12BHN, ultimate compression strength of 240.95N/mm2, % reduction at failure of 1.06%, and wear rate of 0.0895mm3/N/m. The 1% SiC reinforced particulate composite performed better than other compositions, but it is closely followed by 0.5%SiC reinforced particulate composite for the thermal treated compositions in terms of improved mechanical properties. This correlates with their microstructures which all show the precipitation of a second phase.

Synthesis and Improved Photoluminescence of SnF2-Derived CsSnCl3-SnF2:Mn2+ Perovskites via Rapid Thermal Treatment.

We report a rapid synthesis method for producing CsSnCl3:Mn2+ perovskites, derived from SnF2, and investigate the effects of rapid thermal treatment on their photoluminescence properties. Our study shows that the initial CsSnCl3:Mn2+ samples exhibit a double luminescence peak structure with PL peaks at approximately 450 nm and 640 nm, respectively. These peaks originate from defect-related luminescent centers and the 4T1→6A1 transition of Mn2+. However, as a result of rapid thermal treatment, the blue emission is significantly reduced and the red emission intensity is increased nearly twofold compared to the pristine sample. Furthermore, the Mn2+-doped samples demonstrate excellent thermal stability after the rapid thermal treatment. We suggest that this improvement in photoluminescence results from enhanced excited-state density, energy transfer between defects and the Mn2+ state, as well as the reduction of nonradiative recombination centers. Our findings provide valuable insights into the luminescence dynamics of Mn2+-doped CsSnCl3 and open up new possibilities for controlling and optimizing the emission of rare-earth-doped CsSnCl3.

Additive Manufacturing of Piezoelectric Niobium-Doped Lead Zirconate Titanate (PZT-N) by Binder Jetting

Binder jetting is an emerging indirect additive manufacturing technique for ceramic materials, which could be employed to produce application-oriented designed components impossible to achieve with traditional processes and featuring enhanced performances. In our study, niobium-doped lead zirconate titanate (PZT-N) powder, usually processed through the standard press-and-sinter route, was employed as the raw material. First, the powder was characterized in terms of granulometry and flowability to assess its suitability for the printing process. Then, shaping by binder jetting was studied, and the effect of three levels of binder saturation (75–90–105%) on the green bodies was assessed. Finally, the microstructure of the sintered samples was studied using SEM, to investigate the effect of thermal treatments on the grain size distribution and residual porosity (~40%). The piezoelectric properties were measured and compared to those of conventionally processed material. The piezoelectric charge and voltage constants (d33 and g33) were evaluated to determine the possible use of printed parts as porous piezoelectric components to be exploited in hydrophones in the direct mode.

Low Temperature Thermal Treatment of Incineration Fly Ash under Different Atmospheres and Its Recovery as Cement Admixture.

Municipal solid waste incineration fly ash is classified as hazardous waste because it contains dioxins and a variety of heavy metals. It is not allowed to be directly landfilled without curing pretreatment, but the increasing production of fly ash and scarce land resources has triggered consideration of the rational disposal of fly ash. In this study, solidification treatment and resource utilization were combined, and the detoxified fly ash was used as cement admixture. The effects of thermal treatment in different atmospheres on the physical and chemical properties of fly ash and the effects of fly ash as admixture on cement properties were investigated. The results indicated that the mass of fly ash increased due to the capture of CO2 after thermal treatment in CO2 atmosphere. When the temperature was 500 °C, the weight gain reached the maximum. After thermal treatment (500 °C + 1 h) in air, CO2, and N2 atmospheres, the toxic equivalent quantities of dioxins in fly ash decreased to 17.12 ng TEQ/kg, 0.25 ng TEQ/kg, and 0.14 ng TEQ/kg, and the degradation rates were 69.95%, 99.56%, and 99.75%, respectively. The direct use of fly ash as admixture would increase the water consumption of standard consistency of cement and reduce the fluidity and 28 d strength of mortar. Thermal treatment in three atmospheres could inhibit the negative effect of fly ash, and the inhibition effect of thermal treatment in CO2 atmosphere was the best. The fly ash after thermal treatment in CO2 atmosphere had the possibility of being used as admixture for resource utilization. Because the dioxins in the fly ash were effectively degraded, the prepared cement did not have the risk of heavy metal leaching, and the performance of the cement also met the requirements.

Physico-chemical properties of γ-irradiated International Simple Glass (ISG) nuclear waste simulants with low levels of iron impurities

The effect of γ-irradiation on physico-chemical properties of International Simple Glass (ISG) nuclear waste glass simulants with low iron impurities was investigated. The study was performed on glasses produced by Corning Inc. (named ISG-1, ISG-2) following a 0.95 MGy dose. Fourier-transform infrared and Raman spectroscopy, chemical durability tests, dilatometry, differential scanning calorimetry, electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy appraisals were done in comparison with pristine glasses. The data indicated that structural, chemical, and thermal properties were not significantly altered following γ-ray exposure. EPR spectroscopy showed radiogenic signatures from spin defects for the γ-irradiated glasses which were absent in the pristine. Optical absorption also changed significantly for the γ-irradiated glasses which exhibited defects-related features around 3.45 and 2.25 eV. The optical band gap and Urbach energies were then determined and compared with those obtained for the γ-irradiated original ISG produced by Mo-SCI Corporation. PL spectroscopy revealed distinct changes after irradiation showing enhanced high-energy emission, contrasting with the γ-irradiated original ISG. The effects of thermal treatment on optical properties of γ-irradiated glasses were finally evaluated. Potential causes at the origin of the contrasting results are discussed based on the effects of different impurities.

The Effect of Thermal Treatment on the Characteristics of Porous Ceramic-Based Natural Clay and Chitosan Biopolymer Precursors

This study was conducted to determine the role of thermal treatment on the crystallinity and pore characteristics of porous ceramic, which was prepared from natural clay (NC) and chitosan (CS) biopolymer using the gel casting method. CS was used as an environmentally friendly pore-forming agent. The applied temperature treatment was based on thermal analysis (TGA/DTA) results and followed a sintering temperature of 900 to 1100 °C. The results showed that at sintering temperatures from 900 to 1000 °C, the crystallinities of the ceramic decrease (from 76.06 to 74.06%) and the crystallite size decreases (from 35.71 to 34.47 nm) while the lattice strain increases (calculated from the Full Width at Half Maximum (β) of the diffraction peak). The highest porosity of ceramic occurred at a sintering temperature of 1000 °C of 37.82 ± 0.19, but the formation of heterogeneous microstructure was observed. The resulting pore size for all temperature treatments was almost mesoporous (19.1 Å). Based on the results obtained, it is emphasized that the sintering temperature can be used to adjust the porosity and microstructure of porous ceramics.

Evolution of the EUROFER97 microstructure during thermal treatment up to 122,000 h

Detailed knowledge of the microstructural evolution of reduce activation ferritic-martensitic steel EUROFER97 after exposure at high temperatures is essential for determining its applications potential. For this proposal, EUROFER97 was annealed in the temperature range between 450 °C and 650 °C for up to 122,000 h (≈14 years) and subsequently analyzed using transmission electron microscopy (TEM) including high resolution TEM and two-dimensional energy dispersive X-ray (EDX) mapping. The study demonstrates the effects of thermal treatment on the size and composition of the precipitates and allows conclusions about their stability. Application of the extraction replication technique was used to analyze composition and morphology of four particle types present in the untreated EUROFER97: M23C6, VN, TaC and TiN with sufficient statistics. The rapid coarsening of the M23C6 precipitates was observed at 650 °C, while the MX particles were found to be more stable upon thermal treatment. It has been proved that new Laves (WFe2) and modified Z-phases (Cr(V,Ta)N) precipitates are formed in the temperature range from 500 °C to 600 °C. The detailed analysis allows the drawing a time–temperature formation diagram for these two phases, which could be valid for alloys with composition similar to EUROFER97.

Mechanical properties and thermo-chemical damage constitutive model of granite subjected to thermal and chemical treatments under uniaxial compression

Fire, chemical actions, and other hidden dangers during construction and service often threaten tunnels and other underground structures. This study investigated the strength and deformation properties of granite treated with high temperatures and chemical solutions through uniaxial compression tests. Then, a novel statistical damage constitutive model was defined, which considers the initial thermo-chemical damage and loading damage, to discuss the effects of thermal and chemical treatments on the damage evolution of granite during uniaxial compression. The compaction coefficient is proposed to describe the compaction degree of the pore structure induced by thermo-chemical treatment. It is used to modify the proposed damage constitutive model. Finally, the applicability of the modified model and the sensitivity of compaction coefficient are verified and discussed by laboratory data. The results indicate that high temperatures and chemical actions reduce the uniaxial compressive strength and elastic modulus of granite. The modified constitutive model can effectively reflect the compaction characteristics of pore structure induced by thermo-chemical treatment in the initial loading stage. Within 150 ℃, the damage caused by chemical treatment is higher than that by thermal treatment. After thermal treatment at 300 ℃ or above, the thermal damage gradually increases, and the difference in chemical damage caused by different solutions decreases. The rising rate of the damage evolution curve gradually slowed down and changed from nonlinear to linear with increased temperatures.