•Flavonoids were extracted from citrus peel using subcritical water.•Flavonoid yields increased from 40.9–69.0% at 120 °C to 79.6–89.0% at 160 °C.•A two-site kinetic model best described extraction ...and degradation of flavonoids.•Flavonoid diffusion coefficients were affected more by flow rate than temperature.•Activation energy was higher for hesperidin than narirutin and polymethoxyflavones.
Citrus peels are the main source of many important flavonoids, flavanones (hesperidin and narirutin) and polymethoxyflavones (PMFs; sinensetin, nobiletin, and tangeretin), which have antioxidant, anti-inflammatory, anticancer, and cardioprotective properties. In this study, the mechanisms controlling the extraction rates of flavonoids from Citrus unshiu peel using subcritical water (SW) were studied at different temperatures (120–180 °C) and flow rates (1.0–2.0 mL/min). The extraction yields increased from 40.9, 69.0, and 67.4% at 120 °C to 79.6, 81.9, and 89.0% at 160 °C for hesperidin, narirutin, and PMFs, respectively, while decomposition occurred at 180 °C. The extraction rate curves at different flow rates were used to determine whether the extraction was best described by a thermodynamic partitioning or kinetic desorption model. The extraction rate curves showed that the initial extraction phase is fast, while the subsequent phase is slow. The thermodynamic partitioning model did not match with the experimental data for the latter part of the extraction period. The two-site kinetic desorption model fit the entire extraction period very well, suggesting that the extraction of citrus flavonoids was mainly controlled by intra-particle diffusion. Interestingly, this model fit well even at the pyrolysis temperature (180 °C). Therefore, the two-site kinetic model can well describe both the decomposition mechanism and extraction mechanism of citrus flavonoids when using SW. The diffusion coefficient of hesperidin increased about 9.8-fold at 160 °C and 2 mL/min relative to 120 °C and 1 mL/min. The activation energy of hesperidin (37.2–43.8 kJ/mol) was higher than those of narirutin and PMFs (8.2–36.8 kJ/mol). This study showed that the extraction mechanism is mainly affected by intra-particle diffusion, and that use of small amounts of SW, an environmentally friendly solvent, promotes good recovery of flavonoids from citrus peel in a short time.
Motor current signature analysis (MCSA) is widespread in the field as a means of providing remote, online monitoring of industrial induction motor rotor faults. However, numerous cases of false ...indications with MCSA produced due to asymmetries in the rotor structure or load leading to unnecessary inspection or forced outages have been reported. Although alternative test methods under motor standstill or starting transient immune to the false indications have been proposed, a reliable method capable of "online" monitoring is desirable. In this article, a new fault indicator in the airgap or stray flux capable of reliable online detection is proposed. It is shown that the fifth sideband of the rotor rotational speed frequency can provide detection of rotor faults immune to most of the false MCSA indications. Experimental results under the most common false indications are provided to verify the claims made for cases where online MCSA produces false indications. The proposed fault indicator is also shown to be immune to eccentricity and common load defects such as load unbalance and misalignment.
Dietary guidelines recommend the consumption of flavonoid-rich extracts for several health benefits. Although immature Citrus unshiu pomace (ICUP) contains high levels of flavanone glycosides, many ...studies have concentrated on the optimization of flavonoid extraction from mature citrus peels. Therefore, we developed an optimized extraction method for hesperidin and narirutin from ICUP, and evaluated their antioxidant activities using ten different assay methods. The extraction conditions for the highest flavonoid yields based on a response surface methodology were 80.3 °C, 58.4% (ethanol concentration), 40 mL/g (solvent/feed), and 30 min, where the hesperidin and narirutin yields were 66.6% and 82.3%, respectively. The number of extractions was also optimized as two extraction steps, where the hesperidin and narirutin yields were 92.1% and 97.2%, respectively. Ethanol was more effective than methanol and acetone. The ethanol extract showed high scavenging activities against reactive oxygen species but relatively low scavenging activities for nitrogen radicals and reactive nitrogen species. The antioxidant activities showed a higher correlation with hesperidin content than narirutin content in the extracts. This study confirms the potential of an optimized method for producing antioxidant-rich extracts for the functional food and nutraceutical industries.
Glehnia littoralis
, a medicinal herb employed in traditional practices for alleviating fatigue, cough, and a dry throat, is recognized for its beneficial properties due to a diverse array of active ...compounds found in its extracts. For example, the
G. littoralis
roots (Radix Glehniae) mainly contain coumarins and phenolic acids, serving as the primary focus of this study. Despite the widespread use of the tools in various industries and the development of multiple analytical methods for their examination, the edible aerial parts have industrial potential, and there is currently no analytical method available to identify their key components. In this study, a high-performance liquid chromatography method combined with diode array detection (HPLC–DAD) was developed to simultaneously detect 16 phenolic compounds previously reported to be present in the edible aerial parts of
G. littoralis
. The proposed approach included using gradient elution to change the solvent system from water/acetonitrile to water/methanol. Furthermore, the method validation was conducted, assessing its linearity, limit of detection, limit of quantification, precision, accuracy, and recovery, all of which demonstrated satisfactory results. Subsequently, the developed method was applied to quantify the phenolic compounds in various
G. littoralis
samples obtained from different organs, solvent extraction processes, and processing methods. Moreover, the online HPLC-ABTS (2,2ʹ-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assay was used to evaluate the antioxidant capacities of individual constituents, identifying four important antioxidants and estimate the overall antioxidant capacity of the
G. littoralis
extract.
Background and Purpose
Fulminant hepatic failure (FHF) is a fatal clinical syndrome that results in excessive inflammation and hepatocyte death. Mitochondrial dysfunction is considered to be a ...possible mechanism of FHF. Afzelin, a flavonol glycoside found in Houttuynia cordata Thunberg, has anti‐inflammatory and antioxidant properties. The present study elucidated the cytoprotective mechanisms of afzelin against D‐galactosamine (GalN)/LPS induced FHF, particularly focusing on mitochondrial quality control and dynamics.
Experimental Approach
Mice were administered afzelin i.p. 1 h before receiving GalN (800 mg·kg−1)/LPS (40 μg·kg−1), and they were then killed 5 h after GalN/LPS treatment.
Key Results
Afzelin improved the survival rate and reduced the serum levels of alanine aminotransferase and pro‐inflammatory cytokines in GalN/LPS‐treated mice. Afzelin attenuated the mitochondrial damage, as indicated by diminished mitochondrial swelling and mitochondrial glutamate dehydrogenase activity in GalN/LPS‐treated mice. Afzelin enhanced mitochondrial biogenesis, as indicated by increased levels of PPAR‐γ coactivator 1α, nuclear respiratory factor 1 and mitochondrial transcription factor A. Afzelin also decreased the level of mitophagy‐related proteins, parkin and PTEN‐induced putative kinase 1. Furthermore, while GalN/LPS significantly increased the level of fission‐related protein, dynamin‐related protein 1, and decreased the level of fusion‐related protein, mitofusin 2; these effects were attenuated by afzelin.
Conclusions and Implications
Our findings demonstrated that afzelin protects against GalN/LPS‐induced liver injury by enhancing mitochondrial biogenesis, suppressing excessive mitophagy and balancing mitochondrial dynamics.
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the accumulation of protein inclusions and the loss of dopaminergic neurons. Transcranial direct current stimulation (tDCS) ...is a non-invasive brain-stimulating technique that has demonstrated promising results in clinical studies of PD. Despite accumulating evidence indicating that tDCS exerts a protective effect, the mechanism underlying its activity remains unknown. In the present study, we first investigated the neuroprotective effect of tDCS in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model and then evaluated the effect of tDCS on the autophagy pathway. tDCS improved behavioral alterations, increased tyrosine hydroxylase protein levels and suppressed α-synuclein protein levels in MPTP-treated mice. MPTP-treated mice subjected to tDCS also had lower levels of autophagy-related proteins, such as microtubule-associated protein 1 light chain 3 and AMP-activated protein kinase, and higher levels of mechanistic target of rapamycin and p62. In addition, the protein levels of phosphoinositide 3-kinase and brain-derived neurotrophic factor were higher, and the levels of unc-51-like kinase 1 were lower in MPTP-treated mice subjected to tDCS. Our findings suggest that tDCS protected against MPTP-induced PD in a mouse model by modulating autophagy.
Various locomotion techniques are used to navigate and find way through space in virtual environments (VE), and each technique provides different experiences and performances to users. Previous ...studies have primarily focused on static environments, whereas there is a need for research from a different perspective of dynamic environments because there are many moving objects in VE, such as other users. In this study, we compare the effects of different locomotion techniques on the user's spatial knowledge and experience, depending on whether the virtual objects are moving or not. The investigated locomotion techniques include joystick, teleportation, and redirected walking (RDW), all commonly used for VR navigation. The results showed that the differences in spatial knowledge and user experience provided by different locomotion techniques can vary depending on whether the environment is static or dynamic. Our results also showed that for a given VE, there are different locomotion techniques that induce fewer collisions between the user and other objects, or reduce the time it takes the user to perform a given task. This study suggests that when designing a locomotion interface for a specific VR application, it is possible to improve the user's spatial knowledge and experience by recommending different locomotion techniques depending on the degree of environment dynamism and and type of task.
The roles of autophagy-related proteins as diagnostic or monitoring biomarkers in Parkinson's disease (PD) have not been clearly elucidated. We recruited 32 patients with early-stage PD and 28 ...control subjects, and evaluated parkinsonian motor symptoms and dopamine transporter imaging data. Cerebrospinal fluid (CSF) levels of LC3B, Beclin1, and LAMP-2 were estimated using ELISAs, and CSF levels of ATG5, ATG7, and p62 were examined by immunoblotting. Additionally, we also assessed the levels of α-synuclein, total tau, and phosphorylated tau in CSF using ELISAs. Significant differences in the levels of LC3B, LAMP-2, and Beclin1 were observed between the PD and control groups. Using 29.8 pg/mL as the cut-off value for a diagnostic biomarker of PD, CSF LC3B levels exhibited high sensitivity (96.9%) and specificity (89.3%) with an area under the curve of 0.982. Furthermore, LC3B was significantly correlated with the asymmetry index in the caudate and putamen, as estimated by a semi-quantitative analysis of
F N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane (FP-CIT) positron emission tomography (PET). CSF levels of LC3B represented a potential diagnostic and prognostic biomarker of early-stage PD in patients. Based on our findings, molecular biological changes in PD are associated with dysregulation of the lysosomal autophagy pathway.
We extracted and hydrolyzed bioactive flavonoids from
peel using subcritical water (SW) in a semi-continuous mode. The individual flavonoid yields, antioxidant and enzyme inhibitory activities of the ...SW extracts were analyzed. The extraction yields of hesperidin and narirutin increased with increasing temperature from 145 °C to 165 °C. Hydrothermal hydrolysis products (HHP), such as monoglucosides (hesperetin-7-
-glucoside and prunin) and aglycones (hesperetin and naringenin) were obtained in the SW extracts at temperatures above 160 °C. The sum of hesperidin and its HHP in the SW extracts was strongly correlated with antioxidant activities, whereas the contents of hesperetin and naringenin were strongly correlated with enzyme inhibitory activities. Hesperetin exhibited the highest antioxidant activities (2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, ferric-reducing antioxidant power, and oxygen radical absorbance capacity), whereas hesperetin-7-
-glucoside exhibited the highest enzyme inhibitory activities (angiotensin-І converting enzyme (ACE) and pancreatic lipase (PL)). Naringenin exhibited the highest enzyme inhibitory activities (xanthine oxidase and α-glucosidase). PMFs (sinensetin, nobiletin, and tangeretin) also exhibited relatively high inhibitory activities against ACE and PL. This study confirms the potential of SW for extracting and hydrolyzing bioactive flavonoids from
peel using an environmentally friendly solvent (water) and a shorter extraction time.
The pole drop test is the most widely applied off-line test for detecting shorted turns in the field winding of salient pole synchronous motors. It is a simple test where the voltage drop (or ...inductance) of the poles are compared to detect the presence of shorted turns. Although it does not require special test equipment, false indications due to sensitivity problems are common. In this letter, the voltage and inductance distribution between the poles are analyzed under shorted field turn conditions. Some practical insight for enhancing the sensitivity and reliability of the pole drop test are given based on the qualitative analysis and experimental testing on a 30 kVA synchronous motor with shorted field turns. It is shown that the sensitivity of the test is significantly higher when the test is performed with the rotor inserted, which is not reported elsewhere. It is also shown that the reliability of the test can be improved by observing the voltage or inductance in poles adjacent to the pole suspected with shorted turns.
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