Search Results (99)

Foundry aluminum-silicon (Al-Si) alloys, especially those containing Cu and/or Mg, are widely used in casting processes for fabricating lightweight parts. This study focuses on the optimization of the solution heat treatment parameters within the T6 heat treatment of an innovative AlSi7Cu0.5Mg0.3 secondary alloy, aiming at achieving energy savings and reducing the environmental impact related to the production of foundry components for the automotive industry. Different combinations of solution times and temperatures lower than those typically adopted in industrial practice were evaluated, and their effects on tensile properties were investigated on samples machined from as-cast and T6-treated castings produced by pouring the alloy into a steel permanent mold. Thermal analysis (TA) and differential thermal analysis (DTA) were performed to monitor the solidification sequence of microstructural phases as well as their dissolution on heating according to the proposed solution heat treatments. Microstructural analysis by light microscopy (LM) and scanning electron microscopy (SEM), together with Brinell hardness testing, was also carried out to assess the effects of heat treatment parameters. The results suggested that a shorter solution heat treatment set at a temperature lower than that currently adopted for the heat treatment of the studied alloy can still ensure the required mechanical properties while improving productivity and reducing energy consumption. Full article

When a semiconducting sample is illuminated by an intensity-modulated monochromatic light beam with photon energy exceeding the band gap, part of the absorbed energy is directly converted into heat through photon–lattice interactions. This gives rise to a heat source that closely follows the temporal profile of the optical excitation, known as the fast heat source. Simultaneously, another portion of the absorbed energy is used to generate electron-hole pairs. These charge carriers diffuse together and recombine via electron–electron and electron–hole interactions, transferring their kinetic energy to the lattice and producing additional heating of the sample. This indirect heating mechanism, associated with carrier recombination, is referred to as the slow heat source. In this study, we develop a model describing surface temperature variations on the non-illuminated side of a thermally thin semiconductor exposed to a rectangular optical pulse, explicitly accounting for the contribution of surface charge carrier recombinations. Using this model, we investigate the influence of surface recombination velocity and the material’s plasma properties on the time-domain temperature response for both plasma-opaque and plasma-transparent samples. Our results demonstrate that charge carrier recombinations can significantly affect the transient photoacoustic signal recorded using a minimum volume cell, highlighting the potential of time-resolved photoacoustic techniques for probing the electronic properties of semiconductors. Full article

Refining light and heavy oils in different proportions seems attractive, especially in cases of geopolitical, economic, environmental, and logistical constraints. The economical attractiveness could be undermined in cases where incompatibility occurs. The current study explores a highly complex refinery performance during processing a blend consisting of 17 crude oils of which one was extra light, five were light, nine were medium, and two were heavy. A n-heptane dilution test, using centrifugation, was employed to assess the colloidal stability of crude oils. In addition, a previously established correlation to relate crude oil vacuum residue fraction Conradson carbon content to asphaltene peptizability Sa according to ASTM D 7157 was also availed for the purpose of evaluating colloidal stability. It was found that the crude desalter amperage increases with the ${\displaystyle \frac{SBN}{IBN}}$ ratio and Sa reduction, reaching its maximum allowable value of 180 A at the ${\displaystyle \frac{SBN}{IBN}}$ ratio of 1.35, and Sa of 0.64. The ${\displaystyle \frac{SBN}{IBN}}$ ratio was found more reliable in predicting oil compatibility than the other ${\displaystyle \frac{SBN}{{IN}_{max}}}$ ratio used to assess colloidal stability in various research. Along with the increase in crude desalter amperage, fouling of the heat exchangers of a crude oil distillation plant was also recorded. An intercriteria analysis of process data together with crude composition data, and compatibility indices revealed that the amperage enhancement is statistically meaningfully related to an increase in the heaviest crude oil content in the process blend and the compatibility indices ${\displaystyle \frac{SBN}{IBN}}$ ratio and Sa, while the fouling was related only to the content of one of the light crude oils in the processed blend. Full article

This study evaluates the impact of the catalyst-to-oil (C/O) ratio in the 1 to 7 range on the catalytic cracking of vacuum gas oil (VGO). Experiments are conducted using fluid catalytic cracking (FCC)-type catalysts, in a mini-fluidized bench-scale Riser Simulator reactor invented at the Chemical Reactor Engineering Centre (CREC), University of Western Ontario. The CREC Riser Simulator replicates FCC industrial operating conditions such as temperature, species partial pressure, and reaction times. The results indicate that increasing the C/O ratio above 5 slightly impacts VGO conversion, increases light gases yield, decreases light cycle oil (LCO) yield, and stabilizes gasoline yield. These findings align with temperature-programmed desorption (TPD) data, showing how the retention of a larger number of acid sites at a C/O of 7 boosts light gas production and reduces LCO selectivity. These elevated C/O ratios also lead to higher coke formation. The results reported together with future studies conducted by our research team on the impact of higher catalyst flows, larger potential catalyst attrition, higher catalyst loading in the cyclones, and excess heat generated in the catalyst regenerator unit, are of critical value for establishing the impact of C/O ratios in the overall FCC refinery operation. Full article

Railway stations are normally designed with glazing façades and skylights to achieve aesthetic requirements and facilitate visual permeability, but this design can lead to significant energy consumption. The implementation of dynamic external shading systems together with appropriate control strategies can significantly reduce the energy consumption of HVAC systems. This study numerically investigated the lighting and cooling energy consumption of railway stations equipped with external shading systems under various climatic zones, window-to-wall ratios (WWRs), skylight-to-roof ratios (SRRs) and roller-shade performance. The study shows that lighting energy consumption varies most significantly when the shading activation threshold is set between 50 and 200 W/m². The dynamic shading thresholds are influenced by natural lighting and solar heat gain, with the strategy changing from using natural light to reducing solar gain as the SRR increases. This study also provides the optimal activation thresholds and energy-saving rates for railway station buildings in different climatic zones using external roller shades for different external window scenarios. In Guangzhou, using roller shade A in a railway station under the maximum external window scenario achieves energy savings of 36.41%, while in Shanghai and Beijing, the energy savings are 18.12% and 23.13%, respectively. These results provide guidance for the use of dynamic external shading in railway stations in China and for the achievement of energy-reduction targets in the transport and building industries. Full article

Background/Objectives: Vitamin C is a well-known antioxidant with antiviral, anticancer, and anti-inflammatory properties. However, its therapeutic applications are limited by rapid oxidation due to heat and light sensitivity. Aptamin C, which employs aptamers to bind vitamin C, has demonstrated enhanced stability and efficacy. This study investigates the potential of Aptamin C to inhibit the progression of pulmonary fibrosis, a prominent inflammatory lung disease with no effective treatment. Methods: Mice bearing bleomycin-induced pulmonary fibrosis were administered vitamin C or Aptamin C, and their weight changes and survival rates were monitored. Inflammatory cell infiltration was assessed in the bronchoalveolar lavage fluid (BALF), and the degree of alveolar fibrosis was measured by H&E and Masson’s trichrome staining. To elucidate the mechanism of action of Aptamin C, Western blot analysis was performed in HaCaT and lung tissues from bleomycin-induced pulmonary fibrosis mice. Results: The Aptamin C-treated group showed a notably higher survival rate at 50%, whereas all subjects in the vitamin C-treated group died. Histological examination of lung tissue showed that inflammation was significantly suppressed in the Aptamin C-supplemented group compared to the vitamin C-supplemented group, with a 10% greater reduction in cell infiltrations, along with noticeably less tissue damage. Additionally, it was observed that Aptamin C increased SVCT-1 expression in the HaCaT cells and the lung tissues. Conclusions: Taken together, Aptamin C not only increases the stability of vitamin C but also induces an increase in SVCT-1 expression, facilitating greater vitamin C absorption into cells and tissues, thereby inhibiting the progression of symptoms and associated inflammatory responses in pulmonary fibrosis. Full article

This paper presents experimental and theoretical studies of heat transfer through single- and double-glazed windows with electrical heating of the internal surfaces. Heating is achieved by applying a voltage to the low emissivity coating of the inner glass. A thermophysical model has been developed to simulate the heat transfer through these units, allowing us to determine their thermal characteristics. Experimental data are used to validate the numerical model. The resulting heat flux and temperature distributions on the external and internal surfaces of electrically heated double-glazed units are analysed. According to the results of experimental and numerical studies, it was found that the adopted electric heating scheme allows 83–85% of the heat to enter the room and 15–17% is removed to the outside. This makes it possible to increase the radiation component of the heat flow from the window to the room and improve the thermal comfort in the room. In general, this article shows that existing industrial windows with low-emissivity glass surface coating can be upgraded with simple and inexpensive modernisation, without compromising the main function of the window—efficient transmission of visible light—and create an additional (backup) heating device that can work effectively together with the existing heating system in the event of a sudden cold snap at low temperatures (below −20 °C), to prevent condensation of water vapour in the windows, and to prevent condensation on the surface of the window facade wall. Formally, a back-up (emergency) heating system is created in the room, which contributes to the energy sustainability of the building and therefore to energy security in general. Full article

Models of heat transport in solids, being based on idealized elastic collisions of gas molecules, are flawed because heat and mass diffuse independently in solids but together in gas. To better understand heat transfer, an analytical, theoretical approach is combined with data from laser flash analysis, which is the most accurate method available. Dimensional analysis of Fourier’s heat equation shows that thermal diffusivity (D) depends on length-scale, which has been confirmed experimentally for metallic, semiconducting, and electrically insulating solids. A radiative diffusion model reproduces measured thermal conductivity (K = Dρc_P = D × density × specific heat) for thick solids from ~0 to >1200 K using idealized spectra represented by 2–4 parameters. Heat diffusion at laboratory temperatures (conduction) proceeds by absorption and re-emission of infrared light, which explains why heat flows into, through, and out of a material. Because heat added to matter performs work, thermal expansivity is proportional to ρc_P/Young’s modulus (i.e., rigidity or strength), which is confirmed experimentally over wide temperature ranges. Greater uptake of applied heat (e.g., c_P generally increasing with T or at certain phase transitions) reduces the amount of heat that can flow through the solid, but because K = Dρc_P, the rate (D) must decrease to compensate. Laser flash analysis data confirm this proposal. Transport properties thus depend on heat uptake, which is controlled by the interaction of light with the material under the conditions of interest. This new finding supports a radiative diffusion mechanism for heat transport and explains behavior from ~0 K to above melting. Full article

Phase-change materials (PCMs) have gained more attention during the last few decades. As the main function of these materials is to store and release energy in the form of latent heat during phase transitions, they perfectly fulfill the direction of modern research focused on energy-related topics. Although they have basic energy-related properties, recent research shows a need to upgrade those materials in terms of improving their common drawbacks like shape stability, leakage, and poor conductivity. The research related to PCM-based composites leads to imparting some additional functional properties such as different types of conversion abilities or extra performance such as shape memory and thermal protection. Together with a new emerging material group—aerogels (AGs), extra-light and highly porous matrices—PCMs could become functional and multifunctional materials. AG-PCM composites could be implemented in a large variety of applications in different sectors like energy, buildings, medical, defense, space technologies, and more. This study aims to help summarize current trends, methods, and works on PCM–aerogel composites in terms of developing new functional materials, especially for energy conversion purposes but also for improved conductivity, mechanical properties, and flame retardancy. Full article

The combination of high-density, high-time-resolution inorganic scintillation crystals such as Lutetium Yttrium Oxyorthosilicate (LYSO), Yttrium Orthosilicate (YSO) and Bismuth Germanate (BGO) with Silicon Photomultiplier (SiPM) sensors is widely employed in medical imaging, particularly in Positron Emission Tomography (PET), as well as in modern particle physics detectors for precisely timing sub-detectors and calorimeters. During the assembly of each module, following individual component testing, the crystals and SiPMs are bonded together using optical glue and enclosed in a light-tight, temperature-controlled cooling box. After integration with the readout electronics, the bonding is initially tested. The final readout electronics typically comprise Application-Specific Integrated Circuits (ASICs) or low-power Analog-to-Digital Converters (ADCs) and amplifiers, designed not to heat up the temperature-sensitive SiPM sensors. However, these setups are not optimal for testing the optical bonding. Specific setups were developed to test the LYSO + SiPM modules that are already bonded but not enclosed in a box. Through large data collection, small deviations in bonding can be detected if the SiPMs and LYSOs have been thoroughly tested before our measurement. The Monte Carlo simulations we used to study how parameters—which are difficult to measure in the laboratory (LYSO absorption length, refractive index of the coating)—affect the final result. Our setups for particle physics and PET applications are already in use by research institutes and industrial partners. Full article

The Guodian Fe deposit is representative of the newly discovered Qihe–Yucheng high-grade Fe skarn ore cluster, Luxi Block, eastern North China Craton (NCC). The age of the Pandian Fe deposit remains elusive, which hinders the understanding of its metallogenic tectonic background. Phlogopites are recognized in syn-ore stages, and they are closely associated with magnetite in the Guodian skarn Fe deposit. Here, we carried out ⁴⁰Ar/³⁹Ar dating of phlogopite, which can place a tight constraint on the timing of Guodian iron mineralization and shed light on the geodynamic framework under which the Guodian Fe deposit formed. Ore-related phlogopite ⁴⁰Ar/³⁹Ar dating yielded ⁴⁰Ar/³⁹Ar plateau ages of 131.6 ± 1.7 Ma at 890–1400 °C, with the corresponding isochron age being 131.1 ± 2.6 Ma. These two ages are consistent within the error, indicating that they can represent the formation age of the Guodian iron deposit. The mineralization age overlaps the zircon U-Pb age of 124.4 Ma for ore-related Pandian pluton. This age consistency confirms that the iron skarn mineralization is temporally and likely genetically related to Pandian diorite. The present results, coupled with existing isotopic age data, indicate the Guodian skarn Fe deposit formed contemporaneously with large-scale skarn iron mineralization over the Luxi Block in the Late Mesozoic. The available data demonstrated that the eastern NCC was “destructed” in the Late Mesozoic, as marked by voluminous igneous rocks, faulted-basin formation, high crustal heat flow, and widespread metamorphic core complexes in the eastern part of the NCC. It is thus suggested that the Guodian Fe skarn deposits, together with other deposits of similar ages in the Luxi Block and even in the eastern NCC, were products of this craton destruction. Lithospheric extension and extensive magmatism related to the craton destruction may have provided sufficient heat energy, fluid, chlorine, and Fe for the formation of the Fe deposit. Full article

Water deficit is the major stress factor magnified by climate change that causes the most reductions in plant productivity. Knowledge of photosystem II (PSII) response mechanisms underlying crop vulnerability to drought is critical to better understanding the consequences of climate change on crop plants. Salicylic acid (SA) application under drought stress may stimulate PSII function, although the exact mechanism remains essentially unclear. To reveal the PSII response mechanism of celery plants sprayed with water (WA) or SA, we employed chlorophyll fluorescence imaging analysis at 48 h, 96 h, and 192 h after watering. The results showed that up to 96 h after watering, the stroma lamellae of SA-sprayed leaves appeared dilated, and the efficiency of PSII declined, compared to WA-sprayed plants, which displayed a better PSII function. However, 192 h after watering, the stroma lamellae of SA-sprayed leaves was restored, while SA boosted chlorophyll synthesis, and by ameliorating the osmotic potential of celery plants, it resulted in higher relative leaf water content compared to WA-sprayed plants. SA, by acting as an antioxidant under drought stress, suppressed phototoxicity, thereby offering PSII photoprotection, together with enhanced effective quantum yield of PSII photochemistry (Φ_PSII) and decreased quantity of singlet oxygen (¹O₂) generation compared to WA-sprayed plants. The PSII photoprotection mechanism induced by SA under drought stress was triggered by non-photochemical quenching (NPQ), which is a strategy to protect the chloroplast from photo-oxidative damage by dissipating the excess light energy as heat. This photoprotective mechanism, triggered by NPQ under drought stress, was adequate in keeping, especially in high-light conditions, an equal fraction of open PSII reaction centers (qp) as of non-stress conditions. Thus, under water deficit stress, SA activates a regulatory network of stress and light energy partitioning signaling that can mitigate, to an extent, the water deficit stress on PSII functioning. Full article

Silicon carbide (SiC) exhibits intriguing thermo-physical properties such as higher heat capacity and conductivity, as well as a lower density than Ti6Al4V(ELI). These properties make SiC a good candidate for the reinforcement of Ti6Al4V(ELI) with respect to its use as a heat shield in aero turbines to increase their efficiency. The traditional materials used in aircraft structures were required to have a combination of good mechanical properties such as strength, stiffness, and hardness and low weight, as well as low thermo-physical properties such as coefficient of thermal expansion (CTE) and thermal conductivity. The alloy Ti6Al4V(ELI) has a density of 4.45 g/cm³, which is lower than that of structural steel (7.4 g/cm³) and higher than that of aluminium (2.5 g/cm³). Lower density benefits light weighting. Aluminium is the lightest of the traditional materials used but has relatively low strength. The CTE of SiC of 4.6 × 10⁻⁶/K is lower than that of Ti6Al4V(ELI) of 8.6 × 10⁻⁶/K, while the density of SiC of 3.21 g/cm³ is lower than that of Ti6Al4V(ELI) of 4.45 g/cm³. Therefore, from the theory of composites, SiC/Ti6Al4V(ELI) composites are expected to have lower densities and CTEs than those of Ti6Al4V(ELI), thus providing for lightweighting and less thermal related buckling or separation at their joints with carbon/epoxy resin panels. The specific strength, stiffness, and Knoop hardness of SiC of 75–490 kNm/kg, 132 MNm/kg, and 600–3800 GPa, respectively, are generally larger than those of Ti6Al4V(ELI) of 211 KNm/kg, 24 MNm/kg, and 880 GPa, respectively. Therefore, investigating reinforcement of Ti6Al4V(ELI) with SiC particles is worthwhile as it will lead to the formation of composites that are stronger, stiffer, harder, and lighter, with lower values of CTE. For additive manufacturing, this requires initial studies to optimise the process parameters of laser power and scanning speed for single tracks. To print single tracks in the present work, different laser powers ranging from 100 W to 350 W and scanning speeds ranging from 0.3 m/s to 2.7 m/s were used for different SiC volume fraction values of values. To print single layers, different values of hatch distance were used together with the best values of laser power and scanning speed determined elsewhere by the authors for different volume fractions of SiC. Through optical microscopy, the built tracks and their cross sections were examined. By using laser power and scanning speeds of 200 W and 1.2 m/s, and 150 W and 0.8 m/s, respectively, the best tracks at 5% and 10% volume fractions were obtained, whereas the best tracks at 25% volume fraction were achieved using a laser power of 200 W and a scanning speed of 0.5 m/s. Furthermore, the results showed that the maximum SiC volume percentage of 30% resulted in limited or no penetration. Therefore, it is concluded from the study that parts with improved mechanical properties can be produced at SiC volume fractions ranging from 5% to 25%, while parts produced at the high volume fraction of 30% would have unacceptable mechanical qualities for the final part. Full article

IR-783, a commercially available near-infrared (NIR) heptamethine cyanine dye, has been used for selective tumor imaging in breast, prostate, cervical, and brain cancers in vitro and in vivo. Although the molecular mechanism behind the structure-inherent tumor targeting of IR-783 has not been well-demonstrated, IR-783 has unique properties such as a good water solubility and low cytotoxicity compared with other commercial heptamethine cyanine dyes. The goal of this study is to evaluate the phototherapeutic efficacy of IR-783 as a tumor-targeted photothermal agent in human colorectal cancer xenografts. The results demonstrate that IR-783 shows both the subcellular localization in HT-29 cancer cells and preferential accumulation in HT-29 xenografted tumors 24 h after its intravenous administration. Furthermore, the IR-783 dye reveals the superior capability to convert NIR light into heat energy under 808 nm NIR laser irradiation in vitro and in vivo, thereby inducing cancer cell death. Taken together, these findings suggest that water-soluble anionic IR-783 can be used as a bifunctional phototherapeutic agent for the targeted imaging and photothermal therapy (PTT) of colorectal cancer. Therefore, this work provides a simple and effective approach to develop biocompatible, hydrophilic, and tumor-targetable PTT agents for targeted cancer phototherapy. Full article

The phenomenon of dormancy and the evolutionary causes for its development are presented together with the effects of the climatic factors: temperature and light. Shade and darkness have been found to enhance bud breaking in peach. The effects of various temperatures on chilling accumulation, chilling negation and chilling enhancement are described. The way these are computed in the face of global warming is explained, using the dynamic model. When natural chilling is less than that required, there are ways of compensation, up to a certain level. Various horticultural, physical and chemical means to achieve this are described, including bending branches, reducing vegetative vigor, shading the orchard, sprinkling to reduce daytime temperature and the application of various chemicals to break dormancy. When winter chilling is markedly reduced and temperatures increase considerably, the use of dormancy avoidance is suggested in frost-free places. This technique can induce a new growing cycle by avoiding dormancy altogether. However, the best approach is to breed high-quality cultivars requiring much less chilling. Another aspect discussed in this work, independent of the chilling requirement, is the negative effect of heat spells in winter and spring on the abnormal development of flower buds, leading to a low level of the stone fruit set and a reduced yield. Full article