Stability aspects of wind power integration in power systems and microgrids

Wind farms can be located in remote and weak parts of power networks, due to the availability of wind energy. With integration of power from such wind farms, the power system’s stability might be affected especially at higher penetration levels. Instability issues resulting from such incorporations must be addressed to accommodate higher wind power penetration in the power networks. This thesis attempts to analyse the stability issues of power system with integration of variable speed wind turbine technology especially focusing on doubly fed induction generators. Additionally, a microgrid with different inertial and non-inertial sources is examined for enhancing design aspect of such microgrids from stability perspectives. At different penetration levels of wind power, oscillatory modes are identified, and participation factors of the most associated state variables on such oscillatory modes are observed. Flexible ac transmission system based series and shunt devices are found effective in enhancing the small signal stability of such power networks for different wind power penetration levels. Besides, series devices are observed to contribute to an improvement in the transient behaviour of the power system. Similarly, high voltage dc link is also witnessed to positively influence low frequency oscillation damping. Furthermore, this thesis shows that higher voltage gain values of wind farms can contribute to an improvement in the small signal stability for increased wind power penetration. Another observation displays that a doubly fed induction based wind farm can contribute to improving the voltage stability of a distribution network in a steady state operating condition, as well as following disturbances. Based on the study on an isolated microgrid that has a combination of synchronous, converter-based distributed resources, and energy storage systems, it is observed that a suitable modification in such microgrid’s various components and parameters can positively influence its small signal stability

Editorial: Anti-cancer drug delivery: lipid-based nanoparticles

Cancer continues to pose significant challenges that require extensive attention and efforts from the scientific community. The battle against cancer encompasses the development of effective and safe therapeutic approaches. However, achieving this balance is highly complex for anticancer therapies, as they often exhibit intense intrinsic cytotoxicity, affecting both cancerous and healthy cells and resulting in substantial toxicity that limits their clinical utility. A promising strategy to address this challenge involves the selective guidance of therapeutic agents to the cancer site, minimizing off-target effects. Nanotechnology offers powerful tools to engineer smart and targeted therapeutics that preferentially accumulate in cancerous tissues . This preferential localization is achieved through the Enhanced Permeation and Retention (EPR) effect, first reported by Prof. Hiroshi Maeda in 1984 . The EPR effect leverages the leaky vasculature in tumor regions, enabling enhanced infiltration of nanotherapeutics and localizing their therapeutic effects, which is commonly described as "passive targeting ". On the other hand, nanotechnologists may also employ "active targeting" by modifying nanoparticle surfaces with homing ligands that selectively recognize cancer cells . Both passive and active targeting strategies are keys for success of nanoparticle-based drug delivery systems, and serve as a justification for the development of nanotherapeutics. Extensive literature exists on various types of nanoparticles and nanomaterials with potential applications as drug delivery systems.The authors would like to thank to the journal (Frontiers in Oncology) for providing us this opportunity to organize the research topic on "Anti-Cancer Drug Delivery: Lipid-Based Nanoparticles". We thank all the authors who contributed in this topic collection. We are also, very grateful to all the reviewers who participated in the whole manuscript review process.Scopu

Perspective Chapter: Glioblastoma of the Corpus Callosum

Glioma is the most common malignant tumour of the brain, in which glioblastoma (GBM) is the most aggressive form which infiltrates through the white fibre tracts. Corpus callosum (CC) is most invaded by GBM, it carries poor prognosis as mostly these tumours are not touched upon due to the belief of post operative cognitive decline, or there is incomplete resection leading to tumour recurrence. However current advancement in technology, operative techniques and better understanding of nature of CC-GBM, maximal safe resection is being carried out with better outcomes in comparison with the GBM without infiltration of CC

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Free radicals, oxidative stress and importance of antioxidants in human health

Reactive oxygen species (ROS) is a collective term used for oxygen containing free radicals, depending on their reactivity and oxidizing ability. ROS participate in a variety of chemical reactions with biomolecules leading to a pathological condition known as oxidative stress. Antioxidants are employed to protect biomolecules from the damaging effects of such ROS. In the beginning, antioxidant research was mainly aimed at understanding free radical reactions of ROS with antioxidants employing biochemical assays and kinetic methods. Later on, studies began to be directed to monitor the ability of anti-oxidants to modulate cellular signaling proteins like receptors, secondary messengers, transcription factors, etc. Of late several studies have indicated that antioxidants can also have deleterious effects on human health depending on dosage and bio-availability. It is therefore, necessary to validate the utility of antioxidants in improvement of human health in order to take full advantage of their therapeutic potential

In Silico Investigation on the Binding of Organoselenium Compounds with Target Proteins of SARS-CoV-2 Infection Cycle

Since the outbreak of coronavirus disease 2019 (COVID-19), researchers have been investigating the potential of several low molecular weight compounds from both natural and synthetic origins to design anti-viral drugs against SARS-CoV-2. On similar lines, the present study is aimed to evaluate different organoselenium compounds and their sulfur analogues by using a molecular docking approach to inhibit viral proteins like spike (S) glycoprotein (PDB code: 6VXX) and main protease (Mpro) (PDB code: 6LU7) and a host protein, Furin (PDB code: 5MIM), all of which are known to play significant role in SARS-CoV-2 infection cycle. The organoselenium compounds used in the study are mostly in-house synthesized including simple selenium containing amino acids and their derivatives and selenopyridines and their derivatives. The docking calculations were performed using AutoDock Vina. In brief, organoselenium compounds showed stronger binding with the target proteins as compared to their sulfur analogue, except oxidized glutathione. Notably, the most potent docked ligands shared a common structural feature of aromatic amide moieties connected by diselenide bridge. Further, the compounds ebselen diselenide (EbSeSeEb) and nicotinamide diselenide (NictSeSeNict) exhibited the highest binding affinity (in range of ~105 µM-1) to all the above three proteins. Thus, the present investigation highlights the influence of structure and substitution of organoselenium compound on their binding with the SARS-CoV-2 proteins and proposes NictSeSeNict as a candidate molecule for evaluating anti-viral activity against SARS-CoV-2 using preclinical biological models.</p

A supplementary controller for improvement of small signal stability of power system with wind power penetration

Wind power penetration affects the dynamics and operational performance of a conventional power system. This article investigates the stability issues of a power system with the penetration of wind power from a doubly fed induction generator and direct drive synchronous generator. An approach to utilize an existing shunt flexible AC transmission system controller, static VAR compensator, for enhancing the small signal stability of a wind connected power system is discussed here. Supplementary stabilizing control for damping oscillatory modes is applied to static VAR compensator and suitable control input has been selected for the best damping performance of the proposed controller

Steady-state and transient voltage stability analysis of a weak distribution system with a remote doubly fed induction generator-based wind farm

In modern, stressed distribution system, voltage stability is a major concern from planning and operation perspectives. Remote wind farm connected to a weak distribution system through a long line could adversely affect the voltage stability of the respective distribution network. This paper investigates the transient and steady-state voltage issues of a distribution network with a distant doubly fed induction generator (DFIG)-based wind farm. Results show that a distant DFIG-based wind farm could improve the voltage stability of a distribution network with a large motor load in steady-state operating condition as well as following disturbances, like three-phase faults, sudden load tripping, and motor starting

Recent trends in reperfusion in ST elevation myocardial infarction in a South Indian tier-3 city

Aims: In India, larger proportions of patients with ACS present with STEMI. We sought to study the recent trends of reperfusion in patients of acute STEMI. Methods and Results: 1905 patients presenting with acute STEMI enrolled. 1636 (86%) received some form of reperfusion therapy. Streptokinase, 1235 (65%) patients, was the most common mode of reperfusion therapy used followed by primary PCI (205, 10.7%) and tenecteplase (196, 10%). 269 (14%) did not receive any form of reperfusion therapy, the most common reason being late presentation in 230 (85.7%). Patients presenting with STEMI increased from 297 to 446 comparing first and last half-year of study period. The PCI and tenecteplase numbers increased from 19 to 68 and 27 to 97 respectively. Conclusion: There was 20% increase in STEMI every year. Younger patients are least likely to receive primary PCI or tenecteplase. 1 in 8 patients of STEMI did not receive any form of reperfusion therapy