Analysis of a Compact Squeeze Film Damper with Magneto Rheological Fluid

Rotor systems play vital role in many modern day machinery such as turbines, pumps, aeroengines, gyroscopes, to name a few. Due to unavoidable unbalance in the rotor systems, there are lateral and torsional vibrations. Ignoring these effects may cause the system serious damages, which sometimes lead to catastrophic failures. Vibration level in rotor systems is acceptable within a range. Focus in this work is to minimize the vibration level to the acceptable range. One of the ways vibration level can be minimised is by means of providing damping. To accomplish this task in this work a new concept squeeze film damper is made by electro discharge machining which is compact in configuration, is filled with magneto-rheological (MR) fluid and tested out on one support of a Jeffcott rotor. This compact squeeze film damper (SFD) produces damping in a compact volume of the device compared to a conventional SFD. MR fluid is a smart fluid, for which apparent viscosity changes with the application of external magnetic field. This compact damper with MR fluid provides the variable damping force, controlled by an external magnetic field. In this work, proportional controller has been used for providing the control feedback. This MR damper is seen to reduce vibrations in steady state and transient input to the Jeffcott rotor. Parametric study for important design parameters has been done with the help of the simulation model. These controlled dampers can be used for reducing vibrations under different operating conditions and also crossing critical speed

Load Flow Analysis with UPFC under Unsymmetrical Fault Condition

This paper addresses the comparative load flow analysis with and without Unified Power Flow Controller (UPFC) for six buses, three phase transmission line under unsymmetrical faults (L-G, L-L and L-L-G) in simulation model. Unified Power Flow Controller (UPFC) is a typical Flexible AC Transmission System (FACTS) device playing a vital role as a stability aid for large transient disturbances in an interconnected power system. The main objective of this paper is to improve transient stability of the six bus system. Here active and reactive power on load bus of the system considered has been determined under different fault conditions. UPFC has been connected to the system and its effects on power flow and voltage profile of test system has been determined with various line data and bus data for six buses, three lines power system and simulation model by using simulation toolbox has been developed. In this work a versatile model is presented for UPFC inherent order to improve the transient stability and damp oscillation. Index Terms – Unified Power Flow Controller (UPFC), Control, simulation, transients, line to ground fault (L-G), double line to ground fault (L-L-G), double line fault (L-L

Semi-analytical approach-based studies of the squeeze film lubrication between rough porous annular discs: Rabinowitsch fluid model

In recent years, there has been much interest in the effects of porosity and surface roughness (SR) or geometric irregularities between two moving plates under hydrodynamic lubrication. Porous bearings are used extensively in wide range of equipment, including computers, office equipment, home appliances, electric motors, and vehicles. In light of the importance of the aforementioned applications, we explored how SR and porous materials affect annular discs under the condition of a squeeze film. A five-point Gauss quadrature integral formula has been used to examine the characteristics of annular discs and a small perturbation method has been used to discretise the governing Rabinowitsch fluid flow (RFF) equations. The impact of nonlinear parameters on the behaviour of porosity and SR have been visualised in terms of film pressure (FP), load carrying capacity (LCC), and squeeze response time (SRT) of annular discs. Under the conditions of pseudoplastic and dilatant fluids, the effects of SR and porous materials between annular discs have been estimated in the form of the film pressure, LCC, and SRT and are presented in this manuscript as tables and graphs. According to the findings, the performance of an annular disc is significantly affected by porous material and radial roughness patterns. In addition, when RFF is carried through a rough surface and porous media, the performance is found to improve for dilatant fluids but suffer for pseudoplastic fluids

Evolution and Final Fates of a Rotating 25 M⊙_{\odot} Pop III star

In this proceeding, we present the 1-dimensional stellar evolution of two rotating population III (Pop III) star models, each having a mass of 25 M$_{\odot}$ at the zero-age main-sequence (ZAMS). The slowly rotating model has an initial angular rotational velocity of 10 per cent of the critical angular rotational velocity. In contrast, the rapidly rotating model has an initial angular rotational velocity of 70 per cent of the critical angular rotational velocity. As an effect of rotationally enhanced mixing, we find that the rapidly rotating model suffers an enormous mass loss due to the deposition of a significant amount of CNO elements toward the surface after the main-sequence phase. We also display the simulated light curves as these models explode into core-collapse supernovae (CCSNe).Comment: Resubmitted after incorporating minor revision, Part of 3$^{rd}$ BINA conference proceeding

One-step simultaneous liquid phase exfoliation-induced chirality in graphene and their chirality-mediated microRNA delivery

Background: Graphene (G) has been established as an exciting prospect for a broad range of applications owing to its remarkable properties. As the molecular structure of G itself is achiral thus introducing chirality in G by simple attachment of a functional group (a chiral ligand) on the G nanosheet may result in more diverse applications. The recent innovations of G chiral nanosystems have been extended to drug delivery. Herein, we have developed a novel and facile synthesis method for producing chiral G for its application in the chirality-dependent microRNA delivery. Methods: L-graphene and D-graphene were produced in a single step by using chiral L-tyrosine and D-tyrosine as a stabilizing and chiral-inducing agent and applying high-temperature sonication. The chirality of the exfoliated L-graphene and D-graphene was assessed with circular dichroism (CD) spectroscopy and their structural, morphological, and surface evaluations were studied using Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. In addition, an attempt has been made to explore the cell viability, hemocompatibility, cellular uptake, and internalization pathway, chirality-mediated interaction, and microRNA (hsa-miR-205-5p) transfection with C4-2B prostate cancer cells. Results: The CD spectra confirmed the chirality present in the exfoliated L(D)-Graphene. Moreover, the Raman spectrum and TEM data confirmed the formation of multi-layer graphene with asymmetric morphology and a large aspect ratio. L-graphene and D-graphene show cellular compatibility. Chiral preferential binding occurring between miR-205 and D-graphene makes them an exciting prospect for gene delivery. D-graphene exhibits superior hemocompatibility compared to commercially available transfection reagent (Lipofectamine). Cellular uptake is clearly shown by internalization of D-graphene into C4-2B prostate cancer cells. miR-205 efficient delivery utilizing D-graphene was confirmed by transfection efficiency and MTT assay. Conclusions: Our results demonstrated that a direct approach- one-step liquid phase exfoliation-induced chirality in graphene and their selective chirality-mediated microRNA delivery

Development of liposomes using microfluids for delivery of miR-205

Background: The therapeutic application of microRNA(s) in the field of cancer has generated significant attention in research. miR-205 is a tumor suppressor in various cancers. However, the delivery of miR-205 is an unmet clinical need. Thus, the development of liposomal formulation platform to deliver miR-205 is highly sought. The most common applications of liposome formulations are vaccines and anticancer formulations (e.g., mRNA, small molecule drugs). However, large-scale production with precise control of size and size distribution of the lipid-based drug delivery systems (DDSs) is one of the major challenges in the pharmaceutical industry. The objective of this study is to develop liposomal formulation with precise size and optimal for delivery of miR-205. Methods: Microfluidics chip designed based on commercial microfluidic device platform was employed for preparation of liposomes. The device is set for the synthesis of liposome at total flow rate (FRR) 10 ml min−1 and 1:3 flow rate ratio (TFR). To determine the optimal conditions, the effect of different factors including FRR, TFR, and total lipid concentration (lipid and cholesterol) on particle size and size distribution is investigated. Liposomes are also produced by a bulk method to compare the properties of the liposomes formed through these methods. The obtained formulations were tested to analyses different physiochemical properties (DLS, FTIR, DSC, and TGA), stability studies and optimized liposomal formulation was confirmed by examining the intracellular accumulation. Results: All formulations displayed an average size less than 200 nm and exhibited acceptable physicochemical behavior. This design demonstrated high productivity and better control of liposome size and polydispersity index (PDI) than conventional liposome preparation methods. The microfluidic devices were used to produce miR-205-loaded liposomes under different processing conditions which were later characterized and studied in vitro to evaluate their efficiency as a drug delivery system. Conclusions: The obtained results demonstrated that the liposomes can effectively deliver miR-205 into cancer cells. Therefore, the microfluidic devices platform are promising devices for reproducible and scalable manufacturing of liposomal formulation

Exploring potato seed research: a bibliometric approach towards sustainable food security

IntroductionPotato is considered to be complete food that will not only ensure food security but also alleviate poverty. Seed production of potato requires specific temperatures and conditions. In response to the growing emphasis on sustainable production, there has been an increasing focus on research on tuber seed production.MethodsIn our study, we have employed bibliometric analysis to investigate the trends in potato seed research and assess its correlation with sustainable development. Tabular analysis and network analysis are employed in the study to understand the prominent authors and institutions and research trends across time. For this purpose, Biblioshiny and Vosviewer software were used. The steps of bibliometric analysis were used, which included data retrieval from Dimensions software. Owing to its limitations, a major analysis was conducted without affecting the results.Result and discussionIt was found from the analysis that it was SDG 2 that was mostly linked with the theme of potato seed production. The results depicted an increasing trend of publications and citations. Co-authorship analysis of authors showed high linkage among groups of authors that formed clusters while other authors remained disconnected. Among countries United States, China and the United Kingdom had a higher impact on publications and citations. Our analysis showed that there is still scope for collaboration among countries as there is no evidence of multidisciplinary interlinkages. By understanding the current research landscape, identifying influential works and authors, and uncovering collaboration patterns, we can pave the way for future advancements in potato seed production. Ultimately, this research contributes to achieving sustainable agriculture and ensuring food security for future generations

Revealing nature of GRB 210205A, ZTF21aaeyldq (AT2021any), and follow-up observations with the 4K×\times4K CCD Imager+3.6m DOT

Optical follow-up observations of optical afterglows of gamma-ray bursts are crucial to probe the geometry of outflows, emission mechanisms, energetics, and burst environments. We performed the follow-up observations of GRB 210205A and ZTF21aaeyldq (AT2021any) using the 3.6m Devasthal Optical Telescope (DOT) around one day after the burst to deeper limits due to the longitudinal advantage of the place. This paper presents our analysis of the two objects using data from other collaborative facilities, i.e., 2.2m Calar Alto Astronomical Observatory (CAHA) and other archival data. Our analysis suggests that GRB 210205A is a potential dark burst once compared with the X-ray afterglow data. Also, comparing results with other known and well-studied dark GRBs samples indicate that the reason for the optical darkness of GRB 210205A could either be intrinsic faintness or a high redshift event. Based on our analysis, we also found that ZTF21aaeyldq is the third known orphan afterglow with a measured redshift except for ZTF20aajnksq (AT2020blt) and ZTF19abvizsw (AT2019pim). The multiwavelength afterglow modelling of ZTF21aaeyldq using the afterglowpy package demands a forward shock model for an ISM-like ambient medium with a rather wider jet opening angle. We determine circumburst density of $n_{0}$ = 0.87 cm$^{-3}$, kinetic energy $E_{k}$ = 3.80 $\times 10^{52}$ erg and the afterglow modelling also indicates that ZTF21aaeyldq is observed on-axis ($\theta_{obs} < \theta_{core}$) and a gamma-ray counterpart was missed by GRBs satellites. Our results emphasize that the 3.6m DOT has a unique capability for deep follow-up observations of similar and other new transients for deeper observations as a part of time-domain astronomy in the future.Comment: Accepted for Special Issue of Journal of Astrophysics and Astronomy, 2022, Astrophysical jets and observational facilities: National perspective, 05 -09 April 2021, ARIES Nainita

Cytokinin and abiotic stress tolerance -What has been accomplished and the way forward?

More than a half-century has passed since it was discovered that phytohormone cytokinin (CK) is essential to drive cytokinesis and proliferation in plant tissue culture. Thereafter, cytokinin has emerged as the primary regulator of the plant cell cycle and numerous developmental processes. Lately, a growing body of evidence suggests that cytokinin has a role in mitigating both abiotic and biotic stress. Cytokinin is essential to defend plants against excessive light exposure and a unique kind of abiotic stress generated by an altered photoperiod. Secondly, cytokinin also exhibits multi-stress resilience under changing environments. Furthermore, cytokinin homeostasis is also affected by several forms of stress. Therefore, the diverse roles of cytokinin in reaction to stress, as well as its interactions with other hormones, are discussed in detail. When it comes to agriculture, understanding the functioning processes of cytokinins under changing environmental conditions can assist in utilizing the phytohormone, to increase productivity. Through this review, we briefly describe the biological role of cytokinin in enhancing the performance of plants growth under abiotic challenges as well as the probable mechanisms underpinning cytokinin-induced stress tolerance. In addition, the article lays forth a strategy for using biotechnological tools to modify genes in the cytokinin pathway to engineer abiotic stress tolerance in plants. The information presented here will assist in better understanding the function of cytokinin in plants and their effective investigation in the cropping system