Search Results (14,228)

Glioblastoma (GBL) is one of the more malignant primary brain tumors; it is currently treated by a multimodality strategy including surgery, and radio- and chemotherapy, mainly consisting of temozolomide (TMZ)-based chemotherapy. Tumor relapse often occurs due to the establishment of TMZ resistance, with a patient median survival time of <2 years. The identification of natural molecules with strong anti-tumor activity led to the combination of these compounds with conventional chemotherapeutic agents, developing protocols for integrated anticancer therapies. Curcumin (CUR), resveratrol (RES), and its glucoside polydatin (PLD) are widely employed in the pharmaceutical and nutraceutical fields, and several studies have demonstrated that the combination of these natural products was more cytotoxic than the individual compounds alone against different cancers. Some of us recently demonstrated the synergistic efficacy of the sublingual administration of a new nutraceutical formulation of CUR+PLD in reducing tumor size and improving GBL patient survival. To provide some experimental evidence to reinforce these clinical results, we investigated if pretreatment with a combination of CUR+PLD can improve TMZ cytotoxicity on GBL cells by analyzing the effects on cell cycle, viability, morphology, expression of proteins related to cell proliferation, differentiation, apoptosis or autophagy, and the actin network. Cell viability was assessed using the MTT assay or a CytoSmart cell counter. CalcuSyn software was used to study the CUR+PLD synergism. The morphology was evaluated by optical and scanning electron microscopy, and protein expression was analyzed by Western blot. Flow cytometry was used for the cell cycle, autophagic flux, and apoptosis analyses. The results provide evidence that CUR and PLD, acting in synergy with each other, strongly improve the efficacy of alkylating anti-tumor agents such as TMZ on drug-resistant GBL cells through their ability to affect survival, differentiation, and tumor invasiveness. Full article

The flashover mechanism in an aircraft cargo compartment under low pressure was investigated in this study. A series of fire experiments were conducted in a scale model of a one-quarter volume FAA standard aircraft cargo compartment at 96 kPa and 60 kPa. The ignition of single-walled corrugated cardboard was chosen as the criterion of the flashover. The influence of different fire sizes and fuel types on the flashover was studied by comparing the average temperature of the smoke layer, the radiation heat flux at the floor level, and the heat release rate of the fire source. The critical condition and behavior of the flashover were analyzed. The results show that under low pressure, the flashover occurs at a higher temperature and radiation heat flux. Increasing the fire source size brings the flashover forward. At 60 kPa and 96 kPa, the cardboard ignites under a flashover when the average temperature of the smoke layer reaches 551 °C and 450 °C, and the average radiant heat flux at the floor level reaches 19.6 kW/m² and 14 kW/m², respectively. In addition, the minimum fire size for a flashover is directly proportional to the heat of evaporation and inversely proportional to the heat of combustion. Full article

In this study, we evaluated the nonlinear dynamics of convection flow using the thermodynamic variational principle, focusing on scenarios where multiple external forces, such as a thermal gradient and rotational field, are applied to a shallow annular pool. We observed that with the increase in the thermal gradient, the flow changed from an axial flow to a rotational oscillatory flow with the wave amplitudes aligned. Further increasing the temperature difference led to a rotational oscillatory flow characterized by alternating wave generation and annihilation. Our analysis of the flow, considering heat fluxes orthogonal to the thermal gradient, allowed us to describe the flow state as a phase at equilibrium. The state transition of the flow was accompanied by a discontinuous jump in the heat flux, which occurred at the intersection of the entropy production curves. The first transition occurred at a temperature difference $\Delta T=12.4 \mathrm{K} \left(\mathrm{M}\mathrm{a}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{o}\mathrm{n}\mathrm{i} \mathrm{n}\mathrm{u}\mathrm{m}\mathrm{b}\mathrm{e}\mathrm{r},\mathrm{M}\mathrm{a}=1716\right)$ and the second at ΔT = 16.3 K $\left(\mathrm{M}\mathrm{a}=2255\right)$. Analysis based on entropy production could accurately predict the observed transition points. Full article

The multiple working modes, complex working conditions, frequent changes in external heat flux, and high power consumption of communication satellites all pose great difficulties to their thermal design. This paper mainly describes the design of a thermal control system for high-power communication satellites. Firstly, new efficient heat transfer technologies and thermal control materials for spacecraft are introduced. Secondly, the structure and internal heat source of the satellite are introduced. Thirdly, the external heat fluxes are analyzed, and the position of the heat dissipation surface and extreme conditions are confirmed. Then, a thermal control system is designed around the difficulties of thermal control. With heat pipes, the temperature uniformity of +Y deck, −Y deck, and +Z deck increased by 8 °C, 9.9 °C, and 34.2 °C, respectively. Furthermore, the maximum temperature of the power controller, secondary power supply, bidirectional frequency converter, and solid discharge decreased by 32.5 °C, 22.0 °C, 14.0 °C, and 164 °C, respectively. Finally, a thermal balance test is performed. The test results show that the temperatures of the solid-state power amplifier, on-board computer, power controller, secondary power supply, and bidirectional frequency converter meet the requirements of the thermal control indices. In addition, the temperature of thermal-sensitive components such as batteries and the storage tank also meets the requirements. The thermal design scheme is reasonable and feasible, and the thermal balance test verifies the correctness of the thermal design. Full article

This article starts from the premise that one of the global control strategies of the Permanent Magnet Synchronous Motor (PMSM), namely the Direct Torque Control (DTC) control strategy, is characterized by the fact that the internal flux and torque control loop usually uses ON–OFF controllers with hysteresis, which offer easy implementation and very short response times, but the oscillations introduced by them must be cancelled by the external speed loop controller. Typically, this is a PI speed controller, whose performance is good around global operating points and for relatively small variations in external parameters and disturbances, caused in particular by load torque variation. Exploiting the advantages of the DTC strategy, this article presents a way to improve the performance of the sensorless control system (SCS) of the PMSM using the Proportional Integrator (PI), PI Equilibrium Optimizer Algorithm (EOA), Fractional Order (FO) PI, Tilt Integral Derivative (TID) and FO Lead–Lag under constant flux conditions. Sliding Mode Control (SMC) and FOSMC are proposed under conditions where the flux is variable. The performance indicators of the control system are the usual ones: response time, settling time, overshoot, steady-state error and speed ripple, plus another one given by the fractal dimension (FD) of the PMSM rotor speed signal, and the hypothesis that the FD of the controlled signal is higher when the control system performs better is verified. The article also presents the basic equations of the PMSM, based on which the synthesis of integer and fractional controllers, the synthesis of an observer for estimating the PMSM rotor speed, electromagnetic torque and stator flux are presented. The comparison of the performance for the proposed control systems and the demonstration of the parametric robustness are performed by numerical simulations in Matlab/Simulink using Simscape Electrical and Fractional-Order Modelling and Control (FOMCON). Real-time control based on an embedded system using a TMS320F28379D controller demonstrates the good performance of the PMSM-SCS based on the DTC strategy in a complete Hardware-In-the-Loop (HIL) implementation. Full article

Achyranthes japonica Nakai (AJN) is a medicinal plant known to be beneficial for the joints. Since it takes at least two years from sowing to harvesting in an open field, new AJN cultivation strategies are needed to shorten the production period and improve quality. In this study, high-quality AJN is produced as microgreens in a vertical farm using a commercial ginseng soil mix (Myeongpum-Insamsangto, Shinsung Mineral Co., Ltd., Goesan, Republic of Korea) and controlled environmental conditions. The cultivation conditions included a temperature of 23 ± 2 °C, relative humidity of 50 ± 10%, and a photosynthetic photon flux density of 170 ± 15 µmol·m⁻²·s⁻¹. Pre-harvest intermittent UV-B exposure, with an intensity of 1.0 ± 0.3 W/m⁻², was applied for one day before harvest to evaluate its effects, using controlled environmental conditions in the vertical farm. Ultraviolet-B (UV-B) irradiation increases secondary metabolite levels in plants; however, the effect of UV-B on 20-hydroxyecdysone (20E), an indicator of AJN, is unclear. Therefore, we aimed to investigate whether UV-B treatment of AJN microgreens affected growth and secondary metabolites. The treatment group was set to 12 h of continuous UV-B treatment during the day, two 6 h UV-B treatments, and four 3 h UV-B treatments to confirm the effectiveness of regular and intermittent treatment and recovery. Short-term UV-B treatment before harvesting increased phenols, flavonoids, antioxidant capacity, and 20E levels without affecting AJN biomass. The intermittent 6 h UV-B irradiation with a 6 h recovery time stimulated 20E content by approximately 1.4 times compared to the control. These study findings indicate that short-term UV-B treatment before harvesting, an appropriate recovery time, and intermittent UV-B exposure are more effective at increasing 20E content than continuous treatment. This approach provides a promising strategy for improving the nutritional and health benefits of AJN microgreens in vertical farming systems. Full article

Firefighter occupational exposures were categorized as a class 1 (known) carcinogen by the International Agency for Research on Cancer in 2022. As a result, firefighters have become heavily focused on identifying effective and easy to implement decontamination strategies to reduce their chemical exposures. Skin decontamination using wipes post-exposure is one decontamination strategy that every firefighter has available to them. However, firefighters have expressed concerns over the ingredients in the wipe solution increasing dermal absorption. The goal of this study was to determine if the ingredients in skin decontamination wipe solution had any enhancement effect on the dermal absorption of phenanthrene. To determine any enhancement effects, the additive solution of four skin decontamination wipe products was applied to porcine skin 15 min after chemical dosing. The absorption of phenanthrene was tested in vitro using a flow-through diffusion cell system over eight hours. The wipe solution effects on dermal absorption were determined by measuring multiple absorption characteristics including cumulative absorption (µg/cm²), absorption efficiency (% dose absorbed), lag time (minutes), flux (µg/cm²/h), diffusivity (cm²/h), and permeability (cm/h). No penetration enhancement effects were observed in any of the skin decontamination wipe solutions tested; rather, all wipe solutions decreased the absorption of phenanthrene. Slight differences in cumulative absorption among two pairings of skin decontamination wipe solutions, wipes 1 and 3 vs. wipes 2 and 4, were observed, indicating that some ingredients may impact dermal absorption. These findings show that firefighters should continue using skin decontamination wipes to reduce their dermal exposures to fireground contaminants with little concern of increasing the absorption of phenanthrene. Full article

In this article, we report a novel pressure sensing method based on the Hall effect and a hard magnet magnetorheological elastomer (hmMRE). The elastic property of the MRE under pressure was used to generate spatial variation in the magnetic flux density around the MRE, and the variation was detected by the Hall effect device underneath. As the first development in this kind of pressure sensing mechanism, we conducted research for the following three purposes: (1) to verify the Hall effect on the output signal, (2) to understand the sensor output variations under different modes of operation, and (3) to utilize the mechanism as a pressure sensor. We characterized the sensor with its operation parameters, such as signal polarity switching depending on wiring directions, signal amplitude, and offset shift depending on the input voltage. Based on the analyses, we concluded that the Hall voltage represents the pressure applied on the hmMRE, and the new pressure sensing mechanism was devised successfully. Full article

Three-dimensional printing technology continues to evolve, enabling new applications in manufacturing. Extensive research in the field of biomimetics underscores the significant impact of the internal geometry of building envelopes on their thermal performance. Although 3D printing holds great promise for improving thermal efficiency in construction, its full potential has yet to be realized, and the thermal performance of printed building components remains unexplored. The aim of this paper is to experimentally examine the thermal insulation characteristics of prototype cellular materials created using 3D additive manufacturing technologies (SLS and DLP). This study concentrates on exploring advanced thermal insulation solutions that could enhance the energy efficiency of buildings, cooling systems, appliances, or equipment. To this end, virtual models of sandwich composites with an open-cell foam core modeled after a Kelvin cell were created. They were characterized by a constant porosity of 0.95 and a pore diameter of the inner core of the composites of 6 mm. The independent variables included the different material from which the composites were made, the non-uniform number of layers in the composite (one, two, three, and five layers) and the total thickness of the composite (20, 40, 60, 80, and 100 mm). The impact of three independent parameters defining the prototype composite on its thermal insulation properties was assessed, including the heat flux (q) and the heat transfer coefficient (U). According to the experimental tests, a five-layer composite with a thickness of 100 mm made of soybean oil-based resin obtained the lowest coefficient with a value of U = 0.147 W/m²·K. Full article

Plastic is a growing global environmental problem. While much of the focus of anthropogenic microparticles has focused on microplastics and their occurrence in marine systems, anthropogenic microparticles are found in freshwater systems. The Charles River is a highly impacted and historically important river within Massachusetts and runs for 80 miles within the state of MA through a variety of land uses. Microparticle concentrations were found to vary along the length of the river and ranged in concentrations from 1–19 pieces/L, with generally higher concentrations downstream. Microfibers were the dominant (72%) type of microparticles found, and the majority (avg 76%) of microparticles were synthetic. The highest estimated flux of microparticles occurred in May, with an estimated flux of 2 billion microparticles per day via the Charles River into the Boston Harbor. The average annual concentration of microparticles was correlated with land use, with higher concentrations occurring in regions with higher impervious coverage and in areas designated as industrial or high-density residential. Polyester, polypropylene, and polyamides were the dominant plastic polymers. However, seasonal changes in the relative importance of each polymer, along with changes in the abundance and flux rates, indicate that there would be seasonal variability in the type of microparticles exported. Changes in composition occurred between stations and between the head and mouth of the river, suggesting particle retention due to either deposition, degradation, or biological consumption. Full article

Objectives: To study the effects of all-trans retinoic acid (ATRA) on TGF-β2-induced effects of human retinal pigment epithelium cells under normoxia and hypoxia conditions. Methods: Two-dimensionally (2D) and three-dimensionally (3D) cultured ARPE19 cells were subjected to cellular functional analyses by transepithelial electrical resistance (TEER) and an extracellular flux assay (2D), measurement of levels of reactive oxygen species (ROS), gene expression analyses of COL1, αSMA, Zo-1, HIF1α, and PGC1α (2D), and physical property analyses (3D). Results: Under a normoxia condition, treatment with 100 nM ATRA substantially decreased barrier function regardless of the presence of 5 ng/mL TGF-β2 in 2D ARPE19 monolayer cells. Under a hypoxia condition, treatment with ATRA conversely increased barrier function, but the effect was masked by a marked increase in effects induced by TGF-β2. Although ATRA alone did not affect cellular metabolism and ROS levels in 2D ARPE cells, treatment with ATRA under a hypoxia condition did not affect ROS levels but shifted cellular metabolism from mitochondrial respiration to glycolysis. The changes of cellular metabolism and ROS levels were more pronounced with treatment of both ATRA and TGF-β2 independently of oxygen conditions. Changes in mRNA expressions of some of the above genes suggested the involvement of synergistical regulation of cellular functions by TGF-β2 and hypoxia. In 3D ARPE spheroids, the size was decreased and the stiffness was increased by either treatment with TGF-β2 or ATRA, but these changes were unexpectedly modulated by both ATRA and TGF-β2 treatment regardless of oxygen conditions. Conclusions: The findings reported herein indicate that TGF-β2 and hypoxia synergistically and differentially induce effects in 2D and 3D cultured ARPE19 cells and that their cellular properties are significantly altered by the presence of ATRA. Full article

This study proposes novel and modified conventional flow fields for a high-temperature PEM fuel cell, and predicts the fluid dynamic behavior with a 3D, computational fluid dynamics model. Five base flow field patterns (FFPs) are selected: a 4-channel serpentine, a hybrid design, a 2-channel spiral, a dual-triangle sandwich, and a parallel pin-type flow field. For each base FFP, sub-patterns are developed through modification of the channels and ribs. The 4-channel serpentine is taken as the state-of-the-art reference flow field. Simulations are carried out at two different mass flow rates. The result shows that the incorporation of a dead end in flow channels or the merging of channels into a single channel before connecting to the outlet enhances the average and maximum GDL mass flux, but it also increases the pressure drop. The parallel pin-type design-3 and dual-triangle sandwich design-1 exhibit a more even distribution but yield a lower average GDL mass flux than the 4-channel serpentine, which could be beneficial for reducing MEA degradation and thus used at low load conditions where a high mass flux is not needed. In contrast, the uniform hybrid design and 2-channel spiral design-2 provide a higher average and maximum mass flux with a more non-uniform distribution and greater pressure drop. The high average GDL mass flux would be beneficial during high load conditions to ensure enough reactants reach the catalyst. Full article

Rubber (Hevea brasiliensis Muell.) plantations are vital agricultural ecosystems in tropical regions. These plantations provide key industrial raw materials and sequester large amounts of carbon dioxide, playing a vital role in the global carbon cycle. Climate change has intensified droughts in Southeast Asia, negatively affecting rubber plantation growth. Limited in situ observations and short monitoring periods hinder accurate assessment of drought impacts on the gross primary productivity (GPP) of rubber plantations. This study used GPP data from flux observations at four rubber plantation sites in China and Thailand, along with solar-induced chlorophyll fluorescence (SIF), enhanced vegetation index (EVI), normalized difference vegetation index (NDVI), near-infrared reflectance of vegetation (NIRv), and photosynthetically active radiation (PAR) indices, to develop a robust GPP estimation model. The model reconstructed eight-day interval GPP data from 2001 to 2020 for the four sites. Finally, the study analyzed the seasonal drought impacts on GPP in these four regions. The results indicate that the GPP prediction model developed using SIF, EVI, NDVI, NIRv, and PAR has high accuracy and robustness. The model’s predictions have a relative root mean square error (rRMSE) of 0.22 compared to flux-observed GPP, with smaller errors in annual GPP predictions than the MOD17A3HGF model, thereby better reflecting the interannual variability in the GPP of rubber plantations. Drought significantly affects rubber plantation GPP, with impacts varying by region and season. In China and northern Thailand (NR site), short-term (3 months) and long-term (12 months) droughts during cool and warm dry seasons cause GPP declines of 4% to 29%. Other influencing factors may alleviate or offset GPP reductions caused by drought. During the rainy season across all four regions and the cool dry season with adequate rainfall in southern Thailand (SR site), mild droughts have negligible effects on GPP and may even slightly increase GPP values due to enhanced PAR. Overall, the study shows that drought significantly impacts rubber the GPP of rubber plantations, with effects varying by region and season. When assessing drought’s impact on rubber plantation GPP or carbon sequestration, it is essential to consider differences in drought thresholds within the climatic context. Full article

Phase-change materials (PCMs) are widely used in the thermal management of electronic devices by effectively lowering the hot end temperature and increasing the energy conversion efficiency. In this article, numerical studies were performed to understand how temperature instability during the periodic utilization of electronic devices affects the heat-dissipation effectiveness of a phase-change material heat sink embedded in an electronic device. Firstly, three amplitudes of 10 °C, 15 °C, and 20 °C for fixed periods of time, namely, 10 min, 20 min, and 40 min, respectively, were performed to investigate the specific effect of amplitude on the PCM melting rate. Next, the amplitude was fixed, and the impact of the period on heat sink performance was evaluated. The results indicate that under the 40 min time period, the averaged melting rate of PCMs with amplitudes of 20 °C, 15 °C, and 10 °C reaches the highest at 19 min, which saves 14 min, 10 min, and 8 min, respectively, compared with the constant input of the same melting rate. At a fixed amplitude of 20 °C, the PCM with a period of 40 min, 20 min, and 10 min has the highest averaged melting rate at 6 min, 11 min, and 19 min, saving the heat dissipation time of 3 min, 8 min, and 14 min, respectively. Overall, it was observed that under identical amplitude conditions, the peak melting rate remains consistent, with longer periods resulting in a longer promotion of melting. On the other hand, under similar conditions, larger amplitude values result in faster melting rates. This is attributed to the fact that the period increases the heat flux output by extending the temperature rise, while the amplitude affects the heat flux by adjusting the temperature. Full article

With the increasing number of complex well types in the development stage of oil and gas fields, it is becoming increasingly urgent to use remote detection logging while drilling (LWD) to explore the geological structures in a formation. In this paper, the feasibility and reliability of the dipole remote detection of logging while drilling are demonstrated theoretically. For this purpose, we use an asymptotic solution of elastic wave far-field displacement to derive the calculation formula for the radiation pattern and energy flux of an LWD dipole source. The effects of influencing factors, including the source frequency, formation property, drill collar size, and mud parameter, on the radiation pattern and energy flux are analyzed. The results show that the horizontally polarized shear wave (SH-wave) has a greater advantage in imaging the reflector compared with the cases of the compressive wave (P-wave) and vertically polarized shear wave (SV-wave), which indicates the dominance of the SH-wave in dipole remote detection while drilling. The optimal source excitation frequency of 2.5 kHz and inner and outer radii of the drill collar of 0.02 and 0.1 m, respectively, should be considered in the design of an LWD dipole shear wave reflection tool. However, the heavy drilling mud is not conducive to remote detection during logging while drilling. In addition, the reflection of the SH-wave for the LWD condition is simulated. Under the conditions of optimal source frequency, drill collar size, and mud parameters, the reflection of the SH-wave signal is still detected under the fast formation. Full article