Decrease In Frequency Research Articles

BCG-induced DNA methylation changes improve COVID19 vaccine immunity without decreasing the risk for COVID19 infection

Abstract Background The Bacillus Calmette-Guérin (BCG) vaccine induces trained immunity, an epigenetic-mediated increase in innate immune responsiveness. Therefore, this clinical trial evaluated if BCG-induced trained immunity could decrease COVID-19-related frequency or severity. Methods A double-blind, placebo-controlled clinical trial of healthcare workers randomized participants to vaccination with BCG TICE® or placebo (saline). Enrollment included 529 healthcare workers randomized to receive BCG or placebo. Primary analysis evaluated COVID-19 disease frequency, while secondary analysis evaluated coronavirus immunity in a subset of participants. Study enrollment ceased early in December 2020 following introduction of COVID-19-specific vaccines. Results Study enrollment was halted early, prior to reaching the targeted recruitment and was not powered to detect a decrease in COVID-19 frequency. Symptomatic COVID-19 occurred in 21 of 263 and 10 of 266 participants in the BCG and placebo arms, respectively (p= 0.50, Fisher’s exact test). Participants vaccinated with BCG, but uninfected with COVID-19, demonstrated increased coronavirus vaccine immunity (increase spike-inducible levels of TNF, IL6, and IL-1β) twelve months after BCG vaccination compared to participants receiving placebo. Immune responsiveness to COVID-19 antigens correlated with BCG-induced DNA methylation changes. Conclusion Due to early study closure, the study was not powered to evaluate COVID-19 frequency. Secondary analysis demonstrated that twelve months following vaccination, BCG increased coronavirus vaccine immunity compared to those who did not receive BCG. This increase in COVID-19 vaccine immunity correlated with BCG-induced DNA methylation changes.

Design and Characterization of Aceclofenac-Loaded Microballoons using Eudragit with Hydroxypropyl Methylcellulose

Background: Drug delivery systems based on microballoons are one of the promising approaches for gastric retention, especially useful for drugs with site-specific absorption in the stomach. The microballoons are hollow, spherical particles under 200 micrometers, designed to float in the gastric environment. The Aceclofenac formulation of an NSAID is helpful with a half-life of 4–4.3 hours; this delivery form gives a sustained release and maintains constant plasma levels with enhanced bioavailability and decrease in dosing frequency. Methodology: Microballoons of Aceclofenac were prepared using Eudragit RS 100 and Hydroxy Propyl Methyl Cellulose as polymers from the emulsion–solvent diffusion method. In this, the polymers impart stability along with a profile of controlled release. Here, the microballoons was evaluated for physical parameter and the release profile regarding average particle size, floatation percentage, entrapment efficiency, true tapped density, and percentage yield, and FTIR will be carried out on complexes of drug and polymer. Results and Discussion: The prepared microballoons exhibit excellent floating properties and uniformity in size, which aided in long gastric retention. High entrapment efficiency with controlled and sustained release of the drug for an extended period was obtained. FTIR studies indicated that Aceclofenac remained stable in the polymer matrix with no considerable chemical interaction between the drug and the polymers. Conclusion: This research shows promise in microballoons-based delivery systems that could maintain the release for a longer duration from the delivery device with respect to Aceclofenac, which enhances bioavailability and reduces dosing frequencies. Keywords: Aceclofenac, Microballoons, NSAID, Sustain Release Medication, Eudragit RS100, HPMC

Effect of Screen Time and Sugar Consumption Reduction on Sleep Bruxism in Children: A Randomised Clinical Trial.

Sleep bruxism (SB) is associated with alterations in dopamine and serotonin, which are related to increased consumption of added sugar and overuse of screens. The aim of this study was to compare the effect of the interventions 'Food, Fun and Family' (FFF) and Counselling and Education (CE) on the frequency of SB in children. A randomised clinical trial was conducted. Forty-eight participants aged between 4 and 8 years, attending the paediatric clinics of Universidad CES (Colombia) and Hospital Elina de la Serna (Argentina) participated in the study. Subjects were randomised into the FFF (experimental) and CE (regular intervention) groups. The frequency of SB was reported with the Children's Sleep Habits Questionnaire (CSHQ), the consumption of added sugar from items with the HBSC-FFQ and the time of use of screens through a diary in baseline (before starting the intervention), at Week 6 and Week 12. Data were analysed with Kruskal-Wallis test followed by Dunn's post hoc, Mann-Whitney test, a linear mixed model and logistic ordinal regression analyses. The FFF group had a more significant reduction in consumption of added sugar and screen time compared to the CE group (p < 0.05), especially from Week 6 to baseline. Regression analysis showed that reducing TV watching and consumption of added sugar were associated with a decrease in SB frequency, especially in the FFF group (OR < 1, p < 0.05), and the results were consistent across different study environments. The FFF intervention was more effective in reducing the screen time and sugar consumption and thus decreased the frequency of SB, when compared with the CE intervention. ClinicalTrials.gov identifier: NCT05310162.

The Effect of an Educational/Behavioral Intervention on Urinary Inconsistence of Women with Multiple Sclerosis

Introduction: Considering the high prevalence and importance of multiple sclerosis (MS) and its complications, especially urinary incontinence and the need to identify less complicated and effective treatment methods for it, this study aimed to investigate the effect of an educational intervention on urinary incontinence of women with MS. Methods: In this semi–experimental study, 70 MS patients with urinary incontinence, who referred to the affiliated hospitals of Tehran Islamic Azad University 2021–2022, were included non–randomly. Two sessions of 45–minute pelvic floor muscle training, standard method of urination and regulation of fluid intake were provided to the patients. The urinary leakage before and after the intervention were evaluated using ICIQ–UI questionnaire and the results were compared using SPSS v.23. Results: Comparing the post–intervention values with pre–intervention values showed significant decrease in mean frequency of urinary leakage (from 1.19±0.89 to 2.90±1.05; p=0.012), mean amount of urinary leakage (from 4.20±1.49 to 1.49±1.23; p=0.003), and the impact of urinary leakage on the quality of life (from 2.82±0.92 to 1.01±0.75; p=0.012). Conclusion: The educational/behavioral training had a significant effect on urinary control of women with MS and reduced the impact of UI on their QOL; therefore, this method is suggested as an effective, easily applicable, and available tool to be implemented for treatment of urinary incontinence in women with MS.

Experimental investigation on swirling annular liquid film breakup characteristics of prefilming airblast atomizer

In order to further improve the understanding of the liquid film breakup characteristics of prefilming airblast atomizer, the effects of key operating parameters and structural parameters (swirl intensity, diameter and number of injection holes on pilot stage, length of pre-film lip and sleeve angle) on the liquid film pattern of prefilming airblast atomizer were investigated using the high-speed shadow method and the Otsu’s method. The mechanism of liquid film breakage was analyzed, the results show that, with the increase of fuel injection pressure, the spray morphology experiences “columnar-shaped”, “tulip-shaped” and “fully cone-shaped”. Meanwhile, the main fluctuation frequency of liquid film varies from 100.5 Hz in the “columnar-shaped” and “tulip-shaped” to 25.12 Hz in the “fully cone-shaped”. With increasing relative pressure drops of swirler, the film breakup length and film fluctuation frequency decrease, while the film fluctuation amplitude increases. An increase in inner-stage swirl intensities will lead to a reduction in the film breakup distance, while an increase in outer-stage swirl intensities will mainly lead to a larger spray angle. The increase of the diameter and number of injection holes and the length of pre-film lip leads to the rise of the liquid film breakup length, while the decrease of sleeve angle mainly leads to the rise of spray angle, which makes the liquid film more easily broken.

Dynamic behavior and stability analysis of fluid-conveying nano-spiral shells: Modeling, simulation, and parametric study

This paper presents a study on a fluid-conveying nano-spiral shell’s free vibration and stability analysis. The nano-spiral shell with Archimedean cross-section shape is modeled according to the first-order shear deformation (FSDT) and modified coupled stress (MCST) theories. Van der Waals force is modeled based on the Leonard Jones potential for atomic interactions. The fluid-structure interaction equation is derived based on the assumption of slip boundary conditions for the fluid. The Rayleigh-Ritz method is used to obtain the natural frequencies of a macro-size spiral shell to be validated with the finite element method (FEM). The parametric vibration analysis is performed for a nano-spiral shell conveying fluid. The results show that the natural frequencies decrease as the distance between the layers of the nano-spiral shell increases. Additionally, an increase in length results in a decrease in natural frequencies. Stability analysis is conducted, and flutter and divergence bifurcations are accurately studied. The results show that the shell with clamped boundary conditions is more stable than the supported boundary condition due to its higher bending stiffness. As the distance between the layers of the fluid-conveying nano-spiral shell increases, instability occurs at a lower fluid velocity. Conversely, as the thickness of the shell increases, the nanostructure becomes unstable at higher fluid velocities.

Turgor pressure affects transverse stiffness and resonant frequencies of buzz-pollinated poricidal anthers.

Several agriculturally valuable plants store their pollen in tube-like poricidal anthers, which release pollen through buzz pollination. In this process, bees rapidly vibrate the anther using their indirect flight muscles. The stiffness and resonant frequency of the anther are crucial for effective pollen release, yet the impact of turgor pressure on these properties is not well understood. Here, we perform three-point flexure tests and experimental modal analysis to determine anther transverse stiffness and resonant frequency, respectively. Dynamic nanoindentation is used to identify the anther's storage modulus as a function of excitation frequency. We subsequently develop mathematical models to estimate how turgor pressure changes after the anther is removed from a flower, thereby emulating zero water availability. We find that 30 minutes post-ablation, anther stiffness decreases by 60%. Anther resonant frequency decreases by 20% 60 minutes post-ablation. Models indicate turgor pressure in the fresh anther is about 0.2 - 0.3MPa. Our findings suggest that natural fluctuations in turgor pressure due to environmental factors like temperature and light intensity may require bees to adjust their foraging behaviors. Interestingly, anther storage modulus increased with excitation frequency, underscoring the need for more sophisticated mechanical models that consider viscous fluid transport through plant tissue.

Hedging in Medical Articles from Two Pandemics

As academic and scientific disciplines continue to evolve, it remains essential for scholars to present their claims with caution. Hedging, a vital linguistic tool, is pervasive in academic writing, although its boundaries are not strictly defined. This research tracks the changes in the use of hedging within medical literature, underpinning the idea that linguistic patterns reflect societal changes. Our study focuses on the analysis of hedging devices within a corpus of 30 medical articles, spanning two distinct pandemic periods: the 1918-1919 influenza pandemic and the 2020-2021 COVID-19 pandemic. A comprehensive review, involving contextual analysis, was conducted for each article to identify hedging instances. Types of hedges were documented and their frequency was calculated, while ambiguous cases were clarified through in-depth discussions and consistency checks. Our analysis confirms that contextual conditions influence both the frequency and types of hedges used. The results show a significant decrease in overall hedging frequency between the two pandemic periods, with approximators declining sharply while shields remained stable. This shift, along with a reduction in the variety of hedging devices used, suggests an evolution towards more precise quantification and a more formulaic style in scientific writing, while maintaining caution in knowledge claims. The conclusions drawn in this paper contribute to our understanding of scientific discourse and its evolution.

Assessment of Attack Frequency in PFAPA Patients Based on Therapeutic Modalities.

This study aims to present the clinical characteristics of patients with PFAPA syndrome, and to compare the effects of corticosteroid usage, colchicine prophylaxis, and tonsillectomy on the frequency of attacks in patients with PFAPA syndrome. Patients aged between 6 months and 18 years presenting to our Paediatric Rheumatology clinic between 2017 and 2021 who were diagnosed with PFAPA syndrome and followed up for a minimum of 12 months were included in this study. The demographic and clinical characteristics of the patients, laboratory findings, attack durations, and treatments were recorded. Our study, comprised of 195 patients, included four groups: untreated (n = 58), corticosteroid (n = 43), colchicine (n = 62), and tonsillectomy (n = 32). There was no significant difference between the treatment groups in terms of attack frequencies before treatment initiation (p > 0.05). When attack frequencies before and after treatment initiation were observed, a decrease in attack frequency compared to the pre-treatment period was observed in the tonsillectomy group (from 12 to 3 attacks) (p < 0.001) and the colchicine group (from 12 attacks to 1 attack) (p < 0.001). It was noted that using steroids during three or more attacks increased attack frequency compared to the pre-treatment period (p < 0.0001). Tonsillectomy resulted in a more significant reduction in attack frequency compared to the colchicine group (p < 0.001). Using corticosteroids during an attack has been shown to effectively control attacks. However, the repeated use of corticosteroids increases the frequency of attacks. Colchicine prophylaxis leads to a reduction in attack frequency in the majority of cases. Tonsillectomy can successfully control the disease in most cases.

Hedging in Medical Articles from Two Pandemics

As academic and scientific disciplines continue to evolve, it remains essential for scholars to present their claims with caution. Hedging, a vital linguistic tool, is pervasive in academic writing, although its boundaries are not strictly defined. This research tracks the changes in the use of hedging within medical literature, underpinning the idea that linguistic patterns reflect societal changes. Our study focuses on the analysis of hedging devices within a corpus of 30 medical articles, spanning two distinct pandemic periods: the 1918-1919 influenza pandemic and the 2020-2021 COVID-19 pandemic. A comprehensive review, involving contextual analysis, was conducted for each article to identify hedging instances. Types of hedges were documented and their frequency was calculated, while ambiguous cases were clarified through in-depth discussions and consistency checks. Our analysis confirms that contextual conditions influence both the frequency and types of hedges used. The results show a significant decrease in overall hedging frequency between the two pandemic periods, with approximators declining sharply while shields remained stable. This shift, along with a reduction in the variety of hedging devices used, suggests an evolution towards more precise quantification and a more formulaic style in scientific writing, while maintaining caution in knowledge claims. The conclusions drawn in this paper contribute to our understanding of scientific discourse and its evolution.

Cognitive-behavioral therapy in the treatment of patients with chronic migraine and emotional impairment: A prospective randomized trial with a two-year follow-up period

Background. Among patients with chronic migraine (CM), emotional disorders (anxiety, depression) are common, promoting the chronic course of migraine and making treatment challenging. Cognitive behavioral therapy (CBT) is promising in the complex treatment of patients with CM and emotional disorders. However, few randomized studies have been conducted to assess the effectiveness of CBT in this category of patients. Aim. To evaluate the effectiveness of an interdisciplinary program, including CBT, in the treatment of patients with CM and emotional disorders (anxiety, depression). Materials and methods. The study included 176 patients with CM and emotional disorders (55 males and 121 females), mean age 36.2 ±8.7 years. All patients underwent clinical interviews, neurological examinations, and testing using clinical and psychological techniques. Patients were randomized into two groups: Group 1 received the standard of care (preventive and acute treatment pharmacotherapy, lifestyle recommendations, physical activity during the day, detoxification therapy in the presence of drug-induced headache – HA) and CBT in the form of 10 individual face-to-face sessions aimed at treating pain, improving emotional state and daily activity; Group 2 received only the standard of care. All patients were evaluated for clinical and psychological parameters before treatment and at 3, 6, 12, and 24 months after the start of treatment. Results. After 3 months of treatment, a statistically significant (p0.05) improvement was observed in Group 1: a decrease in the HA frequency, the use frequency and daily doses of painkillers, points of the scale for assessing the effect of migraine on daily activity, the pain catastrophizing scale, the Spielberger-Khanin scale of personal and situational anxiety, the depression scale of the Center for Epidemiological Research. The improvements persisted after 6, 12, and 24 months from the start of treatment. After 3 months of treatment, Group 2 patients showed a statistically significant improvement in only four indicators at Month 3 of follow-up: the HA frequency, the use frequency and daily doses of painkillers, points of the scale for assessing the effect of migraine on daily activity. However, no improvements were observed after 6, 12, and 24 months of follow-up in Group 2. After 3 months of treatment, the clinical effect of CM (decrease in the HA frequency by 50% or more) in Group 1 was reported in 74% of patients vs 44% in Group 2, with a significant difference (p0.001). After 24 months of follow-up, 80% of patients in Group 1 had a clinical effect regarding CM, and 31% in Group 2. Conclusion. An interdisciplinary program that includes CBT is significantly more effective than the standard of care for CM and emotional disorders in the short and long term.

Efficacy of cognitive behavioral therapy in chronic migraine and medication overuse headache: a prospective randomized trial

Cognitive behavioral therapy (CBT) is recommended in the complex therapy of chronic migraine (CM) and medication overuse headache (MOH), but there are few randomized trials to evaluate its efficacy.Objective: to investigate the efficacy of an interdisciplinary program with CBT in the treatment of patients with CM and MOH.Material and methods. The study included 156 patients with CM and MOH (61 men and 95 women, mean age 34.1±8.9 years). All patients were clinically interviewed and tested with clinical and psychological methods. Patients were randomized into two groups: group 1 received standard treatment (pharmacotherapy – preventive and for migraine relief; lifestyle recommendations; detoxification therapy in MOB) and CBT, group 2 received only standard treatment. In all patients clinical and psychological parameters were assessed before treatment, and 3, 6, 12 and 18 months after the start of treatment.Results. After 3 months of treatment, a statistically significant improvement (p&lt;0.05) was observed in group 1: reduction in headache frequency, frequency of taking painkillers (PC), scores on the Pain Catastrophizing Scale, the Spielberger–Khanin Personal and Situational Anxiety Scale, Centre for Epidemiologic Studies Depression Scale, Leeds Dependence Questionnaire (LDQ) and the Migraine Disability Assessment (MIDAS) Questionnaire (p&lt;0.05). The improvement achieved was maintained after 6, 12 and 18 months of therapy. After 3 months of therapy, in group 2 a statistically significant improvement (p&lt;0.05) was observed for four parameters only: decrease of headache frequency, frequency of PC use, scores on the LDQ and MIDAS Questionnaire. However, after 6, 12 and 18 months of therapy in group 2, the achieved improvement was not maintained. After 3 months of therapy, the clinical effect (reduction in headache frequency by 50% or more) was achieved in 74% of patients in group 1 and in 45% in group 2 (p &lt; 0.001). After 18 months of therapy, the clinical effect was observed in 79% of patients in group 1 and in 33% of patients in group 2 (p &lt; 0.001).Conclusion. The use of CBT in the complex therapy of patients with CM and MOH is effective and makes it possible to achieve stable positive long-term results.

Near-Inertial Oscillations of Thermocline in the Shelf Area off Vladivostok, the Sea of Japan, from a Set of Thermostrings

The shelf area off Vladivostok in the Sea of Japan is known by the intense internal wave activity investigated for many years. The present contribution to these studies is based on data collected on 3–14 October 2022, from four moorings aligned across isobaths and equipped with thermostrings. Multivariate analysis is performed in the depth–time domain, while timescales and directions and speeds of temperature anomaly movement are estimated from wavelet transform. Approximately 50% of the variance results from vertical stratification changes, i.e., thermocline deepening or shoaling, and temperature anomalies on different timescales moved towards the shoaling seafloor. For the first time, near-inertial (NI) oscillations are detected throughout the record and turn out to be the most intense among the 6 to 70 h timescales, moving with the speeds of 0.41–0.55 m/s, although previous attention was paid to the semidiurnal internal tide. A frequency decrease, i.e., red shift, of the NI oscillations is detected towards shallower water, with the frequency eventually becoming subinertial, and is explained by anticyclonic relative vorticity at the eastern side of the mushroom-like structure detected from thermal satellite imagery. The semidiurnal and two-day oscillations were detected, moving with the speeds of 0.95–1.11 and 0.15–1.17 m/s, respectively. The two-day timescale, never reported before, is considered as a difference one caused by nonlinearity. These results are interpreted as the propagation of an internal wave generated at the steep slope offshore to the inner shelf.

Investigating the decoupling effects between global sustainable development and multi-disaster crises

ABSTRACT Various disasters pose significant challenges to achieving the Sustainable Development Goals (SDGs), highlighting the urgent need for research on global sustainability resilience under multi-disaster crises. This study analyzed the spatiotemporal evolution of disaster frequency, losses, and sustainable development performance from 2000 to 2022. On this basis, we examined the differences in sustainable development under overlapping disaster types and assessed the impact of disaster losses on the 17 SDGs. Finally, decoupling theory was applied to explore the relationships between multi-disaster crises and sustainable development progress. Our findings reveal a global decrease in disaster frequency and an increase in sustainability. However, countries in East and South Asia are disaster hotspots, and many African countries face both frequent disaster shocks and obstacles to sustainable development. Notably, 26.51% and 19.88% of countries experienced overlapping effects from 7 to 8 disaster types, which generally hinder sustainability. We describe the seeking sustainable development under multi-disaster crises as a complex interaction of decoupling processes. Although often exhibits an absolute decoupling and expansive coupling, it is also prone to sudden transition into recessive decoupling or negative coupling, and SDGs are still strongly constrained by disasters. This study highlights the importance of promoting disaster risk management and sustainable development, calling for increased attention and funding investment to assist vulnerable areas establish crisis warning systems and buffer zones.

Associations of smoke-free policies in multi-unit housing with smoking behavior and second-hand smoke exposure: A systematic review.

Although considerable progress has been made regarding the implementation of smoke-free policies (SFPs), many people continue to be exposed to second-hand smoke (SHS) in the home environment. The aim of this study was to conduct a systematic review on the association of SFPs in multi-unit housing (MUH) with smoking behavior and SHS exposure. In August 2022, we searched five online databases: PubMed, Embase, Web of Science, PsycINFO and CENTRAL. Keywords included terms for SFPs, MUH, smoking behavior and exposure to SHS. We searched for studies that focused on regular combustible cigarettes. Due to the high heterogeneity in methodology and outcomes of the included studies, a meta-analysis was not performed. Our search yielded 4750 articles. All of them were screened (24 based on full-text), and 17 met the inclusion criteria. All studies were published between 2001 and 2022. Most studies were conducted in the United States (n = 16) and used a cross-sectional design (n = 7) or a longitudinal design (n = 7). Seven studies evaluated smoking behavior. Five of them reported that SFPs in MUH were statistically significantly associated with decreases in either current smoking, smoking quantity, smoking frequency or smoking cessation. Fourteen studies evaluated exposure to SHS. Ten reported that SFPs in MUH were statistically significantly associated with decreases in self-reported exposure to SHS, airborne nicotine levels and particulate matter levels. Smoke-free policies in multi-unit housing appear to be associated with reduced smoking behavior and second-hand smoke exposure. Successful implementation depends on accessible cessation support and effective enforcement.

Impact of cloud radiative forcing on tropical cyclone frequency and intensity through tuning the cloud ice-to-snow diameter threshold

Abstract Cloud radiative effect (CRE) is crucial for the development of tropical cyclones (TCs). This study investigates the impact of cloud radiation on TC seeds and TCs in an aquaplanet model by tuning “threshold diameter to convert cloud ice particles to snow” (DCS). With increased cloud cover associated with higher DCS, seed frequency decreases, but the greater intensity increase of seeds leads to a higher survival rate from seeds to TCs. The changes in large-scale circulation within the models are responsible for the reduced seed frequency. Higher DCS enhances equatorial cloud liquid and ice amounts, thereby intensifying radiation heating to the tropics. Increased radiation leads to more moisture and higher temperatures at high levels and increases the temperature gradient from the tropics to the subtropics, thereby intensifying the Hadley circulation. The resulting decrease in convective available potential energy and intensification of vertical wind shear due to the act as inhibiting factors for seed genesis. Besides, the presence of more high-level clouds accumulates both longwave and shortwave heating, creating favorable thermal conditions for the circulation to develop at the mesoscale. This process supports the growth of seeds into mature TCs, resulting in higher survival rates from seeds to TCs. The findings on TCs and CRE in aquaplanet models could serve as a foundation and provide evidence for studies conducted in more complex environmental conditions.

The Role of Different Intonation Contours in Social Perception

An extensive body of research has shown that speech plays an important role in social perception.Based on the acoustic quality and prosodic features of speech, listeners make inferences of the speaker’s emotional states, attitudes, personality traits, and other characteristics. Fundamental frequency (f0) and intonation seem to be crucial parameters in forming an impression about the speaker. In the present study, a female speaker, an amateur actress, read 10 Hungarian sentences. We implemented a small change to the sentences, i.e.a 2-semitone decrease of the peak frequency in the intonation contour, technically, on the stressed syllable. Thus, we had the original and a manipulated version of each sentence. Two listener groups were asked to rate the imaginary speaker using a 7-point semantic differential scale with 6 pairs of bipolar adjectives (not natural–natural, uncertain–self-confident, sad–happy, nervous–calm, unpleasant–pleasant, pessimistic– optimistic).Ratings of the original and the manipulated versions of the same sentence did not differ significantly in general. However, there were several cases where differences were significant (p .05) or approached the conventional level of significance (p .01), especially in the dimension of “optimism”, suggesting a less favourable state of the speaker when sentences with lowered intonation peak were heard.

Estimation of Quantitative Inertia Requirement Based on Effective Inertia Using Historical Operation Data of South Korea Power System

In low-inertia systems with a high penetration of renewable energy, the rotational kinetic energy and inertia constant are significant factors in determining frequency stability. The energy released owing to the frequency decrease during contingency represents a portion of the inertia that a synchronous machine possesses in the normal state. However, when securing inertia or planning additional resources to secure frequency stability, inertia in the normal state is analyzed as the standard rather than the amount of energy released during a fault. Therefore, in this paper, we define the actual energy emitted from a synchronous machine as Effective inertia. In order to evaluate Effective inertia in various operating conditions, we conducted a comprehensive review on approximately 24,627 cases from the years 2019, 2020, and 2021. As a result, in systems with low rotational kinetic energy, both low- and high-frequency nadirs were observed, indicating high uncertainty. However, Effective inertia presented a consistent trend regarding the energy release aligned with the minimum frequency. For instance, the rotational kinetic energy required to satisfy the frequency standard was 23 GWs, while the required Effective inertia was 858 MWs. We emphasize that securing inertia based on rotational kinetic energy includes additional imaginary energy that does not contribute to frequency, resulting in an energy requirement greater than that needed for Effective inertia. Therefore, in order to secure the frequency stability of the future system, the actual required energy amount based on Effective inertia will be presented and utilized in the inertia market and FFR (Fast Frequency Response) resource design.

A New Method for Complex Impedance Measurement of Power Transformers via a Continuous Wavelet Transform

The Fourier transform is widely accepted as the time-to-frequency conversion procedure, although it has some limitations. Currently, measurements in the time domain are usually transient (non-periodic waveforms) within a finite window time and discrete (non-continuous) sampled signals. The accuracy of the Fourier transform decreases as the window time and sampling frequency decrease. This is where the wavelet transform proves to be a valuable tool in this analysis. This paper presents a novel method for estimating the complex electrical impedance of power transformers by analyzing transient electrical signals with the continuous wavelet transform. The great importance of knowing the complex electrical impedance of the transformer is that it allows knowing the state and condition of the internal parts, such as the core and the windings, whose behavior depends on the frequency with which the transformer is fed. The wavelet transform is employed in the proposed method to improve the analysis of the frequency response (FRA), following the same procedure commonly used with the Fourier transform. The proposed method is validated by performing an experimental test on a 28 MVA power transformer. The results show that the new method using the continuous wavelet transform is a power tool that enhances the extraction of the total electrical impedance curve (magnitude–phase) compared to the Fourier transform. This enables real-time frequency response analysis in transformers, facilitating accurate diagnosis.

Electrophoresis and Quartz Crystal Microbalance Instrumentation to Sense Nanoplastics in Water.

We report a Technical Note on detecting nanoplastics in water samples through electrophoresis and quartz crystal microbalance (QCM) instrumentation. We conducted electrophoresis experiments by immersing a QCM in a sample of ultrapure water containing polyethylene (PE) nanoplastics. It was interesting to observe that nanoplastics were attracted toward the QCM and adhered to one side of the QCM electrode. The attached particles introduced mass loading to the QCM and were characterized by a decrease in resonance frequency of the crystal. Furthermore, when a small region around the center of electrode was alone exposed for direct contact in water and the rest of the electrode was masked using photoresist, the nanoplastics were concentrated only in the exposed electrode region, significantly enhancing detection sensitivity. To further investigate the applicability for real-life water samples, we experimented with the technique with readily available bottled drinking water and mineral water, where we spiked these water samples with nanoplastics. It was observed that the resonance frequency shifts were significantly larger for samples with nanoplastics compared to samples without nanoplastics. In addition, Raman spectroscopy and microscopy imaging were used to further confirm the presence and locations of nanoplastics on the electrode surface. This study highlights the combination of electrophoresis and QCM effectiveness in detecting nanoplastics across different water types and their potential for broader applications in environmental monitoring.