Search Results (11)

Purpose: No prior clinical studies have quantitatively evaluated the effect of low-dose radiation therapy (LDRT) on Alzheimer’s disease (AD) brain changes using multi-modal MRI. This study examined the feasibility of using conductivity, diffusion, and brain tissue volume measures to detect treatment effects in patients with AD receiving LDRT. Methods: Nine patients with mild AD were enrolled in three groups. Three patients in each group were assigned to the control group (0 cGy) and the treated groups [24 cGy/6 fractions (4 cGy for each fraction) and 300 cGy/6 fractions (50 cGy for each fraction)]. Conductivity, diffusivity, and brain tissue volume were acquired at baseline and 6 months post-treatment and were evaluated to assess within-group MRI changes and evaluate associations between MRI measures and Mini-Mental State Examination (MMSE) scores. Results: Region-of-interest (ROI) analyses identified substantial changes in high-frequency conductivity (HFC) (e.g., left insula), cerebrospinal fluid (CSF) volumes (e.g., anterior cingulate, limbic regions), and diffusion tensor imaging (DTI) metrics, such as axial diffusivity (AxD) and fractional anisotropy (FA), in fusiform, thalamic, hippocampal, and occipital areas. Correlation analysis showed strong associations between MRI measures and cognition, most notably HFC in the left fusiform gyrus (r = 0.843, p = 0.0043) after treatment. Diffusion indices across multiple regions also showed significant positive or negative correlations with MMSE. Conclusions: This exploratory clinical study demonstrates that LDRT induces measurable physiological and microstructural alterations in the brain detectable via conductivity and diffusion MRI. Conductivity emerged as the sensitive biomarker, showing strong cognitive correlations. These exploratory findings suggest that multi-modal quantitative MRI can serve as an effective tool for evaluating treatment response in clinical LDRT for AD. Full article

Hexafluoroethane and 1,1,1,3,3,3-hexafluoropropane (abbreviated as HFC-236fa and R-116, respectively, referred to as C₂F₆ and C₃H₂F₆ based on their molecular formulas) were selected as the object to study the corrosion effects of gas fire-extinguishing agents on different metal materials in the storage state. Typical metal materials used in storage containers including 304 stainless steel, Q235 carbon steel, 6061 aluminum alloy, H59 brass, and T2 copper were subjected to full-immersion corrosion experiments under simulated storage conditions with high-pressure and alternating high–low temperature cycles. High-definition cameras, a scanning electron microscope (SEM), high-precision electronic balances, an energy-dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS) were used to explore the corrosion characteristics. The chemical reactions and mechanisms were analyzed. The results indicate the following: (1) A thin corrosion layer appears on the surface of the metal with varying degrees of severity but low prevalence. (2) The corrosion rates of C₂F₆ and C₃H₂F₆ were comparable and varied in the following order: 6061 aluminum alloy > Q235 carbon steel > H59 brass > 304 stainless steel > T2 copper. (3) C₃H₂F₆ is slightly higher than C₂F₆ in all corrosion rate values. (4) The corrosion of metal materials is mainly attributed to the reaction between metal elements and the F-containing groups produced by the cleavage of C₂F₆ and C₃H₂F₆. The generated metal halides in turn catalyze the cleavage of C₂F₆ and C₃H₂F₆. This catalytic effect may be positively correlated with the reactivity of the metal element. (5) The higher corrosive activity of C₃H₂F₆ compared to C₂F₆ is attributed to the ease of C–C bond cleavage, catalyzed by metal halogens. This study provides theoretical insights into the corrosion ability of halogenated alternatives as a replacement for halon-based fire extinguishers. Full article

Organic Rankine Cycle (ORC) power plants represent one of the most suitable technologies for the recovery and conversion of low-grade thermal energy. Coupling a micro-scale ORC system with parabolic trough collectors (PTCs) as a thermal energy source can effectively meet the electrical and thermal demands of a domestic user. This study presents the development process of the micro-ORC system, detailing both the results of the numerical model and the implementation of the test prototype. Particular attention is given to the instrumentation and sensors installed on the test bench, the monitoring and data acquisition software, and the error propagation analysis applied to the experimental data. In order to develop a micro-scale ORC plant, a commercial hermetic scroll compressor was tested as an expander with HFC-245fa working fluid. The test campaign required the construction of a dedicated experimental setup, equipped with comprehensive monitoring and control systems. While the first part of this research focused on evaluating the use of a scroll compressor as an expander, the second part aims to thoroughly describe the design of the test bench and the numerical model employed, the boundary conditions adopted, and the optimization strategies implemented to enhance system performance. This paper also describes in detail the measurement methodology and the associated error analysis to ensure comparability between experimental and numerical data. The numerical model was experimentally validated by incorporating the actual measured efficiency of the pump system, estimated at 12%. The comparison revealed a deviation between the experimental and simulated absorbed power of the pump—expressed as a function of the evaporation pressure—of less than 10% in the majority of the tested operating conditions. This confirms the reliability of the model and supports its use in future optimization studies. Full article

Noah-2100A and HFE-649, as two electronics fluorinated liquids (EFLs) with low saturation temperature, high safety, excellent insulation properties, and low environmental impact, are considered as replacements for the refrigerants with high Global Warming Potential (GWP), such as HFC-134a and HFC-245fa, in electronic cooling system. However, there is still a knowledge gap of boiling heat transfer for these two EFLs, especially in pin-fin microchannel. The effect of inlet temperatures, mass flow rates, and inlet vapor qualities on boiling heat transfer for two EFLs were studied experimentally in this paper. Overall, though the Noah-2100 has a higher pressure drop-in microchannel than HFE-649, Noah-2100A shows a higher overall thermal performance than HFE-649. Newly developed correlations of the Nusselt number (Nu) and pressure drop for two EFLs in a pin-fin microchannel heat sink were also presented. The proposed correlations can achieve a 10% and 11% mean average percentage error for Nu number and pressure drop. Full article

In order to reduce greenhouse gas emissions and achieve global decarbonisation, it is essential to find sustainable and renewable alternatives for electricity production. In this context, the development of distributed generation systems, with the use of thermodynamic and photovoltaic solar energy, wind energy and smart grids, is fundamental. ORC power plants are the most appropriate systems for low-grade thermal energy recovery and power conversion, combining solar energy with electricity production. The application of a micro-scale ORC plant, coupled with Parabolic Trough Collectors as a thermal source, can satisfy domestic user demand in terms of electrical and thermal power. In order to develop a micro-scale ORC plant, a commercial hermetic scroll compressor was tested as an expander with HFC-245fa working fluid. The tests required the construction of an experimental bench with monitoring and control sensors. The aim of this study is the description of the scroll performances to evaluate the application and develop optimization strategies. The maximum isentropic effectiveness is reached for an expansion ratio close to the volumetric expansion ratio of the scroll, and machine isentropic effectiveness presents small variations in a wide range of working conditions. The filling factor is always higher than one, due to leakage in the mechanical seals of the scroll or other inefficiencies. This study demonstrates that using a commercial scroll compressor as an expander within an ORC system represents a valid option for such applications, but it is necessary to improve the mechanical seals of the machine and utilize a dedicated control strategy to obtain the maximum isentropic effectiveness. Full article

The last decade (2013–2023) was the most prolific period of organic Rankine cycle (ORC) research in history in terms of both publications and citations. This article provides a detailed review of the broad and voluminous collection of recent internal combustion engine (ICE) waste heat recovery (WHR) studies, serving as a necessary follow-on to the author’s 2013 review. Research efforts have targeted diverse applications (e.g., vehicular, stationary, and building-based), and it spans the full gamut of engine sizes and fuels. Furthermore, cycle configurations extend far beyond basic ORC and regenerative ORC, particularly with supercritical, trilateral, and multi-loop ORCs. Significant attention has been garnered by fourth-generation refrigerants like HFOs (hydrofluoroolefins), HFEs (hydrofluoroethers), natural refrigerants, and zeotropic mixtures, as research has migrated away from the popular HFC-245fa (hydrofluorocarbon). Performance-wise, the period was marked by a growing recognition of the diminished performance of physical systems under dynamic source conditions, especially compared to steady-state simulations. Through advancements in system control, especially using improved model predictive controllers, dynamics-based losses have been significantly reduced. Regarding practically minded investigations, research efforts have ameliorated working fluid flammability risks, limited thermal degradation, and pursued cost savings. State-of-the-art system designs and operational targets have emerged through increasingly sophisticated optimization efforts, with some studies leveraging “big data” and artificial intelligence. Major programs like SuperTruck II have further established the ongoing challenges of simultaneously meeting cost, size, and performance goals; however, off-the-shelf organic Rankine cycle systems are available today for engine waste heat recovery, signaling initial market penetration. Continuing forward, next-generation engines can be designed specifically as topping cycles for an organic Rankine (bottoming) cycle, with both power sources integrated into advanced hybrid drivetrains. Full article

Polyurethane rigid foam is a widely used insulation material, and the behavior characteristics and heat absorption performance of the blowing agent used in the foaming process are key factors that affect the molding performance of this material. In this work, the behavior characteristics and heat absorption of the polyurethane physical blowing agent in the foaming process were studied; this is something which has not been comprehensively studied before. This study investigated the behavior characteristics of polyurethane physical blowing agents in the same formulation system, including the efficiency, dissolution, and loss rates of the physical blowing agents during the polyurethane foaming process. The research findings indicate that both the physical blowing agent mass efficiency rate and mass dissolution rate are influenced by the vaporization and condensation process of physical blowing agent. For the same type of physical blowing agent, the amount of heat absorbed per unit mass decreases gradually as the quantity of physical blowing agent increases. The relationship between the two shows a pattern of initial rapid decrease followed by a slower decrease. Under the same physical blowing agent content, the higher the heat absorbed per unit mass of physical blowing agent, the lower the internal temperature of the foam when the foam stops expanding. The heat absorbed per unit mass of the physical blowing agents is a key factor affecting the internal temperature of the foam when it stops expanding. From the perspective of heat control of the polyurethane reaction system, the effects of physical blowing agents on the foam quality were ranked in order from good to poor as follows: HFC-245fa, HFC-365mfc, HFCO-1233zd(E), HFO-1336mzzZ, and HCFC-141b. Full article

This work developed a novel method for measuring the effective rate of a PBA (physical blowing agent) and solved the problem that the effective rate of a PBA could not be directly measured or calculated in previous studies. The results show that the effectiveness of different PBAs under the same experimental conditions varied widely, from approximately 50% to almost 90%. In this study, the overall average effective rates of the PBAs HFC-245fa, HFO-1336mzzZ, HFC-365mfc, HFCO-1233zd(E), and HCFC-141b are in descending order. In all experimental groups, the relationship between the effective rate of the PBA, $r_{ePBA}$, and the initial mass ratio of the PBA to other blending materials in the polyurethane rigid foam, $w$, demonstrated a trend of first decreasing and then gradually stabilizing or slightly increasing. This trend is caused by the interaction of PBA molecules among themselves and with other component molecules in the foamed material and the temperature of the foaming system. In general, the influence of system temperature dominated when $w$ was less than 9.05 wt%, and the interaction of PBA molecules among themselves and with other component molecules in the foamed material dominated when $w$ was greater than 9.05 wt%. The effective rate of the PBA is also related to the states of gasification and condensation when they reach equilibrium. The properties of the PBA itself determine the overall efficiency, while the balance between the gasification and condensation processes of the PBA further leads to a regular change in efficiency with respect to $w$ around the overall average level. Full article

Maternal obesity during pregnancy adversely impacts offspring health, predisposing them to chronic metabolic diseases characterized by insulin resistance, dysregulated macronutrient metabolism, and lipid overload, such as metabolic-associated fatty liver disease (MAFLD). Choline is a semi-essential nutrient involved in lipid and one-carbon metabolism that is compromised during MAFLD progression. Here, we investigated under high-fat (HF) obesogenic feeding how maternal choline supplementation (CS) influenced the hepatic lipidome of mouse offspring. Our results demonstrate that maternal HF+CS increased relative abundance of a subclass of phospholipids called plasmalogens in the offspring liver at both embryonic day 17.5 and after 6 weeks of postnatal HF feeding. Consistent with the role of plasmalogens as sacrificial antioxidants, HF+CS embryos were presumably protected with lower oxidative stress. After postnatal HF feeding, the maternal HF+CS male offspring also had higher relative abundance of both sphingomyelin d42:2 and its side chain, nervonic acid (FA 24:1). Nervonic acid is exclusively metabolized in the peroxisome and is tied to plasmalogen synthesis. Altogether, this study demonstrates that under the influence of obesogenic diet, maternal CS modulates the fetal and postnatal hepatic lipidome of male offspring, favoring plasmalogen synthesis, an antioxidative response that may protect the mouse liver from damages due to HF feeding. Full article

This study aimed at investigating the anti-obesity and anti-dyslipidemic effects of Stachys sieboldii Miq. root (SS) powder in rats following a high-fat and high-cholesterol (HFC) diet for 6 weeks. Thirty-two Sprague–Dawley rats were fed one of the following diets: a regular diet (RD), HFC, HFC supplemented with 3% SS (HFC + 3SS) or HFC supplemented with 5% SS (HFC + 5SS). Following an HFC diet increased body weight (BW) gain (p < 0.001) and the food efficiency ratio (FER; p < 0.001); however, SS consumption gradually prevented the HFC-induced BW gain (p < 0.001) and increase in FER (p < 0.01). The HFC diet resulted in increased liver size (p < 0.001) and total adipose tissue weight (p < 0.001), whereas the SS supplementation decreased hepatomegaly (p < 0.05) and body fat mass (p < 0.001). SS consumption prevented the increased activities of serum alanine aminotransferase (ALT; p < 0.001), aspartate aminotransferase (AST; p < 0.001), alkaline phosphatase (ALP; p < 0.01 in HFC + 5SS) and lactate dehydrogenase (LDH; p < 0.001 in HFC + 5SS) induced by the HFC diet (p < 0.001). The SS supplementation improved lipid profiles in the circulation by lowering triglyceride (TG; p < 0.01), total cholesterol (TC; p < 0.001) and non-HDL cholesterol (non-HDL-C; p < 0.001) levels, as well as the atherogenic index (p < 0.01) and cardiac risk factor (p < 0.01). The lipid distribution in the liver (p < 0.05) and white adipose tissues (WAT; p < 0.001) of the HFC + SS diet-consuming rats was remarkably lower than that of the HFC diet-consuming rats. The average size of the epididymal adipose tissue (p < 0.001) was significantly lower in the HFC + SS diet-fed rats than in the HFC diet-fed rats. The fecal lipid (>3% SS; p < 0.001) and cholesterol (5% SS; p < 0.001) efflux levels were significantly elevated by the SS supplementation compared to those measured in the RD or HFC diet-fed groups. In addition, the hepatic lipid and cholesterol metabolism-related gene expressions were affected by SS consumption, as the hepatic anabolic gene expression (Acc; p < 0.001, Fas; p < 0.001 and G6pdh; p < 0.01) was significantly attenuated. The HFC + 5SS diet-fed rats exhibited elevated hepatic Cyp7a1 (p < 0.001), Hmgcr (p < 0.001) and Ldlr (p < 0.001) mRNA expression levels compared to the HFC diet-fed rats. These results suggest that SS may possess anti-adipogenic and lipid-lowering effects by enhancing lipid and cholesterol efflux in mammals. Full article

Cr₂O₃ nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr₂O₃ and Cr₂O₃ prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr₂O₃ catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH₃-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF₃CH₂CHF₂, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF₃CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr₂O₃ prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr₂O₃ and commercial Cr₂O₃, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr₂O₃, Cr₂O₃-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr₂O₃ prepared by SCS after reaction was not detected, indicating high resistance to sintering. Full article