Search Results (16)

Endothelial dysfunction driven by oxidative and nitrosative stress is a critical factor in the pathogenesis of diabetes-related vascular complications. This study investigated the antioxidant and anti-inflammatory effects of Gymnema inodorum leaf (GiL) extract and its flavonoid constituents, kaempferol and quercetin, on human umbilical vein endothelial cells (HUVECs) exposed to peroxynitrite-induced stress. Peroxynitrite exposure significantly reduced the mRNA levels of antioxidant enzymes (e.g., catalase, glutathione peroxidase 1, superoxide dismutase 1, and superoxide dismutase 2) while increasing the expression of pro-inflammatory cytokines (e.g., tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, interleukin-10, and interleukin-12), ultimately leading to oxidative stress and cellular damage. Treatment with GiL extract reversed these effects by enhancing the defenses of antioxidants through the upregulation of enzymatic mRNA expression and suppressing inflammation via the downregulation of cytokine gene expression. The flavonoid constituents of the extract were identified as the active compounds responsible for these protective effects, with kaempferol and quercetin exhibiting significant free radical scavenging activity and the modulation of inflammatory signaling pathways. High doses of GiL extract showed greater efficacy in restoring cellular homeostasis and preventing oxidative damage. These findings underscore the potential of Gymnema inodorum as a source of bioactive compounds for preventing and managing endothelial dysfunction and other oxidative stress-related complications in diabetes. Full article

The growing urgency of climate change underscores the need for enhanced green management practices across organizations, particularly for small and medium enterprises (SMEs), the backbone of economic development. Green inclusive leadership (GIL) is defined as a leadership approach that emphasizes inclusivity, openness, and support for employees’ green ideas and contributions, fostering alignment with organizational environmental objectives. This study examines the influence of GIL on green knowledge sharing (GKS), green organizational identity (GOI), and green innovation (GI) within diverse Chinese industries, including manufacturing, services, media, and IT. Using data from 625 valid survey responses collected from 700 predominantly young, educated employees, this research demonstrates that GIL has a direct positive impact on GKS, GOI, and GI. The findings further reveal that GKS and GOI significantly contribute to GI, highlighting their roles as critical drivers of green innovation. Additionally, GKS and GOI partially mediate the relationship between GIL and GI, providing insights into how GIL promotes sustainable practices and innovation. This study underscores the importance of leadership and collaborative organizational practices in fostering a green-oriented organizational climate, supporting adopting green business models essential for competitive and resilient enterprises in a sustainable economy. Full article

The advanced Gas Insulated Switchgear/Gas Insulated Lines (GIS/GIL) transmission equipment serves as an essential physical infrastructure for establishing a new energy power system. An analysis spanning nearly a decade on faults arising from extra/ultra-high voltage discharges reveals that over 60% of such faults are attributed to the discharge of metal particles and dust. While existing technical means, such as ultra-high frequency and ultrasonic sensing, exhibit effectiveness in online monitoring of particles larger than sub-millimeter dimensions, the inherent randomness and elusive nature of micron-nano dust pose challenges for effective characterization through current technology. This elusive micron-nano dust, likely concealed as a latent threat, necessitates special attention due to its potential as a “safety killer”. To address the challenges associated with detecting micron-nano dust and comprehending its intricate mechanisms, this paper introduces a micron-nano dust adsorption experimental platform tailored for observation and practical application in GIS/GIL operations. The findings highlight that micron-nano dust’s adsorption state in the electric field predominantly involves agglomerative adsorption along the insulator surface and diffusive adsorption along the direction of the ground electrode. The pivotal factors influencing dust movement include the micron-nano dust’s initial position, mass, material composition, and applied voltage. Further elucidation emphasizes the potential of micron-nano dust as a concealed safety hazard. The study reveals specific physical phenomena during the adsorption process. Agglomerative adsorption results in micron-nano dust speckles forming on the epoxy resin insulator’s surface. With increasing voltage, these speckles undergo an “explosion”, forming an annular dust halo with deepening contours. This phenomenon, distinct from the initial adsorption, is considered a contributing factor to flashovers along the insulator’s surface. The physical mechanism behind flashovers triggered by micron-nano dust is uncovered, highlighting the formation of a localized short circuit area and intense electric field distortion constituted by dust speckles. These findings establish a theoretical foundation and technical support for enhancing the safe operational performance of AC and DC transmission pipelines’ insulation. Full article

A synthetic partial discharge (PD) calibrator has been developed to qualify PD analyzers used for insulation diagnosis of HVAC and HVDC grids including cable systems, AIS, GIS, GIL, power transformers, and HVDC converters. PD analyzers that use high-frequency current transformers (HFCT) can be qualified by means of the metrological and diagnosis tests arranged in this calibrator. This synthetic PD calibrator can reproduce PD pulse trains of the same sequence as actual representative defects (cavity, surface, floating potential, corona, SF₆ protrusion, SF₆ jumping particles, bubbles in oil, etc.) acquired in HV equipment in service or by means of measurements made in HV laboratory test cells. The diagnostic capabilities and PD measurement errors of the PD analyzers using HFCT sensors can be determined. A new time parameter, “PD Time”, associated with any arbitrary PD current pulse i(t) is introduced for calibration purposes. It is defined as the equivalent width of a rectangular PD pulse with the same charge value and amplitude as the actual PD current pulse. The synthetic PD calibrator consists of a pulse generator that operates on a current loop matched to 50 Ω impedance to avoid unwanted reflections. The injected current is measured by a reference measurement system built into the PD calibrator that uses two HFCT sensors to ensure that the current signal is the same at the input and output of the calibration cage where the HFCT of the PD analyzer is being calibrated. Signal reconstruction of the HFCT output signal to achieve the input signal is achieved by applying state variable theory using the transfer impedance of the HFCT sensor in the frequency domain. Full article

Accidents always occur in gas-insulated switchgears (GIS) and gas-insulated lines (GIL) since filmed joint electrodes are produced when internal gases react with the electrode’s surface when there is a discharge or when internal electricals overheat. To solve the problem, this paper analyzed the evolution of elements on the contact electrode. The reaction of the SF6 and electrode’s surface under breakdown currents and overheating conditions was obtained, and the discharge time and discharge current effects upon the transfer of the element were proposed. It was found that the mobility of the F element on the electrode’s surface typically increases after electrical heating. The number of interruptions and short-circuit currents are important factors affecting the transfer of the F element to the electrode. The flashover current is the essential factor that accelerates the transfer of the F element to insulating materials. Frequent switching is a main factor that accelerates the transfer of the F element to the contact. It was also found that Al has little correlations with the breaking process, and metal fluorides become the main components on the electrode’s surface under discharge heating. The research provides a theoretical basis and data support for GIS/GIL surface optimization treatments and the improvement of fault detection methods. Full article

Spacers for the HVDC GIS/GIL play an important role in mechanically supporting conductors and separating compartments. At the same time, their insulation performance affects the stability and safety of system operation. Design rules and knowledge specific to AC spacers do not apply to those of DC spacers. Considering the shape influence on the surface electric field intensity of the spacer under HVDC applied voltage, as determined in our previous work, an optimized shape of a spacer model based on finite element electric field calculations and using standard HVAC alumina filled epoxy material and two novel types of materials were studied. The simulation’s results show that the DC shape optimization of the spacers can effectively reduce the electric field magnitudes along the spacer under different temperature gradients. To verify practically these findings, this paper presents the reduced scale gas insulated prototype that was constructed, the optimized DC spacers that were fabricated and the DC testing results using SF₆-free surrounding gas: C4-Perfluoronitrile (C4-PFN, 3M^TM Novec^TM 4710)/CO₂ and Trifluoroiodomethane (CF₃I)/CO₂. The results show that the shape-optimized spacer models made of conventional HVAC filled epoxy material have successfully passed the tests up to the maximum applicable ±123 kV DC exceeding thus ±119 kV DC that corresponds to the nominal voltage ±500 kV DC of the full scale. Full article

Paramyosins, muscle proteins occurring exclusively in invertebrates, are abundant in seafoods. The potential of seafood paramyosins (SP) as sources of anti-angiotensin-converting-enzyme (ACE) and anti-dipeptidyl-peptidase (DPP-IV) peptides is underexplored. This in silico study investigated the release of anti-ACE and anti-DPP-IV peptides from SP after gastrointestinal (GI) digestion. We focused on SP of the common octopus, Humboldt squid, Japanese abalone, Japanese scallop, Mediterranean mussel, Pacific oyster, sea cucumber, and Whiteleg shrimp. SP protein sequences were digested on BIOPEP-UWM, followed by identification of known anti-ACE and anti-DPP-IV peptides liberated. Upon screening for high-GI-absorption, non-allergenicity, and non-toxicity, shortlisted peptides were analyzed via molecular docking and dynamic to elucidate mechanisms of interactions with ACE and DPP-IV. Potential novel anti-ACE and anti-DPP-IV peptides were predicted by SwissTargetPrediction. Physicochemical and pharmacokinetics of peptides were predicted with SwissADME. GI digestion liberated 2853 fragments from SP. This comprised 26 known anti-ACE and 53 anti-DPP-IV peptides exhibiting high-GI-absorption, non-allergenicity, and non-toxicity. SwissTargetPrediction predicted three putative anti-ACE (GIL, DL, AK) and one putative anti-DPP-IV (IAL) peptides. Molecular docking found most of the anti-ACE peptides may be non-competitive inhibitors, whereas all anti-DPP-IV peptides likely competitive inhibitors. Twenty-five nanoseconds molecular dynamics simulation suggests the stability of these screened peptides, including the three predicted anti-ACE and one predicted anti-DPP-IV peptides. Seven dipeptides resembling approved oral-bioavailable peptide drugs in physicochemical and pharmacokinetic properties were revealed: AY, CF, EF, TF, TY, VF, and VY. In conclusion, our study presented in silico evidence for SP being a promising source of bioavailable and safe anti-ACE and anti-DPP-IV peptides following GI digestions. Full article

A diagnosis scheme using the Hurst exponent for metal particle faults in GIL/GIS is proposed to improve the accuracy of classification and identification. First, the diagnosis source signal is the vibration signal generated by the collision of metal particles in the electric field. Then, the signal is processed via variational mode decomposition (VMD) based on particle swarm optimization with adaptive parameter adjustment (APA-PSO). In the end, fault types are classified and identified by an SVM model, whose feature vector is composed of the Hurst exponents of each intrinsic mode function (IMF-H). Extensive experimental data verify the effect of this new scheme. The results exhibit that the classification performance of SVM is significantly improved by the new feature vector. Furthermore, the VMD based on APA-PSO with adaptive parameter adjustment can effectively enhance the decomposition quality. Full article

The aim of this study is to analyze the skeletal and dentoalveolar morphological characteristics of the maxillary in subjects with a unilateral palatally impacted canine using Cone Beam Computed Tomography (CBCT). A retrospective clinical study was conducted of 100 adult patients divided into two groups: one consisting of patients with a unilaterally palatally impacted maxillary canine (GI), with the subgroups in the right and left hemiarches (GI-R and GI-L), and the second, without impacted canine, as the control group (CG). The CBCT measured skeletal variables (maxillary basal width and alveolar crest height) and dentoalveolar variables (inclination of the upper incisor, tooth lengths of incisors and canines, arch length, tooth size and bone dental discrepancy). In skeletal variables, statistically significant differences were found in alveolar crest height (ACH) in all groups and subgroups (p < 0.01). In the dentoalveolar variables, there were differences in the angle of the upper incisor (II) and lateral incisor length (LLIL) between the GI and GC and the angle of the upper incisor (II′), arch length (AL′) and arch length-tooth size discrepancy (ATD′) among the GI subgroups (p < 0.01). There are skeletal and dentoalveolar differences in patients with unilateral palatally impacted maxillary canines, with lower angular and linear measurements compared with patients without impaction. Full article

Research indicates that a woman’s lifestyle during pregnancy influences her child’s health and development. Therefore, women need to possess sufficient knowledge regarding the elements of a healthy lifestyle during pregnancy. To date, there has been little research on the assessment of lifestyle knowledge of pregnant women in the perinatal healthcare setting. This study describes the development and application of a knowledge-based questionnaire for pregnancy to be used in a lifestyle intervention trial conducted in Germany. Within the trial, pregnant women receive counselling on lifestyle topics. These topics are based on the German initiative ‘Healthy Start—Young Family Network’ (GiL), which provides evidence-based recommendations regarding diet and lifestyle before and during pregnancy. These serve as a basis for health professionals who provide counselling on healthy lifestyle choices during the antenatal period. The questionnaire consists of eight items, each of which can be answered using ‘Yes’, ‘No’ or ‘Don’t know’. The pregnant women who completed the questionnaire at baseline around the twelfth week of gestation were recruited within the host trial from gynaecological practices in Germany. Demographic variables and the respondents’ answers to the questionnaire were analysed using descriptive statistics and regression analyses. Descriptive statistics show that more than 85% of participants answered the majority of questions (n = 5) correctly. Questions on whether tap water is safe and the normal range for gestational weight gain (GWG) were answered correctly by about 62% and 74% of the women, respectively, and the question on whether it is beneficial to obtain information on breastfeeding at an early stage was answered correctly by about 29%. The results of the regression analyses indicate that age, gestational week, education and income are positive predictors for answering the questionnaire correctly. Nullipara and migration background are predictors for answering the questions incorrectly. This study indicates that there are gaps in women’s knowledge regarding lifestyle during pregnancy. Particular focus on certain topics, such as breastfeeding and normal GWG ranges, is still required during counselling. Our analysis shows that migration background is a predictor of insufficient knowledge and incorrect answers to the questions. Women with such backgrounds require special attention during antenatal counselling in order to cater to their needs and the gaps in their knowledge. Full article

Due to the ever-increasing demand for electricity in the one hand and the environmental constraints to use clean energy on the other hand, the global production of energy from remote renewable sources, particularly from large hydropower plants and offshore wind farms and their connection to the grid are expected to grow significantly in the future. Consequently, the demand to carry this electric power by high voltage direct current (HVDC) technology will increase too. The most suitable HVDC power transmission technology to deliver large amounts of power, exceeding a capacity of 5 GW per bipolar system over long distances with lower losses is by using compact HVDC gas insulated transmission lines (DC GIL) and gas insulated switchgears (DC GIS) with rated voltage (maximum continuous operating voltage) of ±550 kV and 5000 A which are presently under development worldwide. Among the critical challenges for the development of these HVDC gas insulated systems, there are the epoxy cast resin insulators that are used to separate gas compartments also called spacers. Indeed, thorough research studies have been and still being carried out to well understand and clarify the electrical insulation characteristics of HVDC spacers using mainly cylindrical samples and small insulator models, where useful results have been obtained and proposed for implementation in real compact gas insulated systems. However, few practical investigations have been undertaken on real size spacers (product scale) to verify such research outcomes and validate the reliability of the spacers to collect experiences or for commercial use. This paper reviews the current achievements of real size HVDC spacers development. It describes the basic electric field calculation and spacers design, the verification of the insulation performance and validation testing. It gives today’s commercially available compact HVDC GIS/GIL and finally it presents the envisaged future research and development. Full article

This study integrated a focus on geographical, physical, and commercial characteristics to explore the commercial gentrification phenomenon and its related statistical summaries in the area of Garosu-gil in Seoul’s Sinsa-dong ward. In particular, this study first collected parcel and building data and corresponding attribute information and mapped the resulting datasets in a geographic information system (GIS) environment. We then examined gentrification issues per building and conducted statistical analyses to investigate spatial patterns of commercial gentrification, which were used to develop criteria for determining degrees of gentrification. Third, this study conducted correlation and regression analyses to quantify the strength of the linear relationship between pairs of variables associated with primary factors contributing to commercial gentrification, and used a geographically weighted regression model (GWR) to help understand and predict spatial relationships between significant variables. The results showed positive correlations between several variables and commercial gentrification in the study area, namely neighborhood-convenience facilities, building ages, store rents, new franchise and restaurant businesses, distance to subways, and the presence of multiple roads. Based on its finding, there are key contributions of this study as follows. The first significant contribution of this study is developing measurement of gentrification levels that can be used by policy makers at each of four stages of the gentrification process. Furthermore, this paper develops a comprehensive approach for spatially identifying gentrifying neighborhoods across multiple time periods in 2- and 3-dimensions. It eventually helps urban planners implement preventative or supportive programs to protect lower-income residents and small businesses and thereby engender more sustainable community development. Full article

Testing and validating the electrical insulation performance of full-size compact high-voltage direct current (HVDC) gas-insulated systems, gas-insulated transmission lines (GIL) and gas-insulated switchgears (GIS) is very costly and take long time. Therefore, a reduced scale system was designed and constructed to study thoroughly the spacer’s performance when subjected to higher electric fields under HVDC with different shapes, made of new advanced materials, and housed in new SF₆-free gas environment. Since the stationary DC electric field distribution along the spacer is controlled by spacer material conductivity and strongly depends upon its shape, this, the first part of two articles, proposes in a first step based on electric field calculations with COMSOL Multiphysics software, an optimized shape of a spacer model using a standard high-voltage alternating current (HVAC) alumina-filled epoxy material. Then, two novel types of materials were introduced and investigated: (i) modified filled epoxy material with a lower temperature-dependent conductivity than that of the standard HVAC material, which is interpreted by a lower thermal activation energy; and (ii) nonlinear resistive field grading material with a low nonlinearity coefficient, with and without the presence of a temperature gradient which occurs under operating service load. The numerical results show that, despite that the DC optimized profile of the spacer made of standard HVAC, alumina-filled epoxy is very effective in relaxing the electric field magnitudes along the spacer under uniform temperature—its distribution is significantly affected by the presence of a high temperature gradient causing the maximum electric field shifts along the spacer surface towards the earthed flange. Under this condition, the modified filled epoxy material with a weaker temperature-dependent conductivity results in a significant reduction of the electric field enhancement, representing thus a relevant key solution for HVDC GIL/GIS applications. Nonlinear resistive field grading material is also effective but seems unnecessary. The optimized DC spacer models are being fabricated for tests verification with C4-Perfluoronitrile (C4-PFN, 3M^TM Novec^TM 4710)/CO₂ and Trifluoroiodomethane (CF₃I)/CO₂ gas mixtures in the reduced scale gas-insulated test prototype. Full article

This paper uses practical experimentation to analyse the effect of replacing SF₆ with pure CO₂ in conventional gas insulated transmission line sections by studying partial discharge measurements taken with applied voltages up to 242 kV (rms). The results can also help in understanding the properties of new alternative gas mixtures which can be utilised with a ratio of up to and over 95% CO₂. The experiments undertaken involved filling a gas insulated line demonstrator with 3 bars of CO₂ and applying voltages up to 242 kV in both clean conditions and particle-contaminated enclosure conditions. The results demonstrate that CO₂ can be used to insulate gas equipment without breakdown at high voltage, however, a higher gas-filling pressure may be needed to reduce the partial discharge found in the tests presented in this paper. Another aspect of the work showed that partial discharge (PD) measurements from internal ultra-high frequency (UHF) sensors compared with a direct measurement from a capacitive divider both clearly showed the effect of contaminating particles in CO₂. However, the PD divider measurements also showed considerable external PD on the outside of the gas compartment, leading to the conclusion that UHF sensors are still regarded as having the highest sensitivity and noise immunity for gas insulated switchgear (GIS) or gas insulated transmission line (GIL) systems including when the equipment is insulated with CO₂. Full article

Increasing demand for an alternative insulation medium to sulphur hexafluoride (SF₆) has led to the investigation of new environmentally friendly insulation gases which could be used in high voltage equipment on the electrical power network. One such alternative, which is currently being explored by researchers, is Trifluoroiodomethane (CF₃I) which could potentially be used in a gas mixture with carbon dioxide (CO₂) as an insulation medium. In this paper an analysis of gaseous by-products detected as a result of high voltage breakdown through pure CF₃I and a CF₃I-CO₂ gas mixture across a sphere-sphere electrode arrangement is given. Gas chromatography and mass spectrometry (GCMS) is used to identify the gaseous by-products produced as a result of high voltage arcing which causes the gas between the electrodes to dissociate. Analysing these gas by-products helps to identify the long-term behaviour of the gas mixture in high voltage equipment. Full article