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The resilience of the power grid is taking a vital role in the energy supply and distribution process. But due to the rapid growth of integration of renewable distributed energy sources to the traditional power grid, the nature of the trading system is shifted from the centralized to decentralized or distributed manner. Blockchain is one of the most emerging security technologies that change the dimension of the financial and energy sector with openness and complete freedom. Blockchain implemented distributed energy trading promotes decentralized electricity markets. The physical system consists of the planning of the routing of energy from one place to another. A user can not send power to another customer in any severe outage or natural disaster in a traditional system. The user cannot participate in the trade globally. So in this proposed methodology, the connections of each customer to the central grid through several microgrids have been shown. In this work, an innovative approach in trading and finding a solution to a payment method is proposed. Ethereum blockchain-based smart contracts completed the entire trading system in automation mode in our proposed system. Any power outage at one place can be compensated by routing a new path of energy inflow from another active source, which enhances the system’s resiliency to a certain degree. While trading, no third parties will be engaged so that the transaction is efficient and fast.

Protein isoforms are structural variants with changes in the overall flexibility predominantly at the tertiary level. For membrane associated proteins, such structural flexibility or rigidity affects membrane stability by playing modulatory roles in lipid-protein interaction. Herein, we investigate the protein chain flexibility mediated changes in the mechanistic behavior of phospholipid model membranes in the presence of two well-known isoforms, erythroid (ER) and nonerythroid (NER) spectrin. We show dramatic alterations of membrane elasticity and stability induced by spectrin in the Langmuir monolayers of phosphatidylocholine (PC) and phosphatidylethanolamine (PE) by a combination of isobaric relaxation, surface pressure-area isotherm, X-ray scattering, and microscopy measurements. The NER spectrin drives all monolayers to possess an approximately equal stability, and that required 25-fold increase and 5-fold decrease of stability in PC and PE monolayers, respectively. The untilting transition of the PC membrane in the presence of NER spectrin observed in X-ray measurements can explain better membrane packing and stability.

The asymmetric distribution of phospholipids in cell membranes has been the focus of a lot of important research keeping its biological importance in mind. Most of this research is focused on phosphatidylserine (PS) since it is an apoptotic marker, and there is a robust and easy method available its selective quantification. The aim of this commentary is to argue in favour of another highly abundant membrane lipid, phosphatidylethanolamine (PE) almost always associated with PS. PE has one of the smallest headgroups and shows distinctly asymmetric transbilayer distribution. It is a neutral aminophospholipid and capable of a vastly wider range of interactions as seen in its unique ability to act as a molecular chaperone, implicated role in disease biology and its possible role as an anti-cancer target. There are ample evidences to the fact that PE may also bind to Annexin V (ANV), the PS-specific probe, at higher than 10 mol% PE concentrations and absence of Ca2+ ions. An update of the major takeaways from the literature regarding PE asymmetry is also provided.

Characterization of the nanoparticle protein corona has gained tremendous importance lately. The parameters which quantitatively establish a specific nanoparticle–protein interaction need to be measured accurately since good quality data are necessary for the elucidation of the underlying mechanism and accurate molecular dynamics simulation. Here, we have employed surface sensitive second harmonic light scattering (SHLS) for investigating the adsorption of a tetrameric protein, alcohol dehydrogenase (ADH, Saccharomyces cerevisiae 147 kDa), on 16 nm, 27 nm, 41 nm, and 69 nm citrate capped gold nanoparticles (GNPs) in aqueous phosphate buffer at pH 7. We have extracted the binding constant, number of ADH bound per GNP, Gibbs free energy (ΔG°) from the decay of the second harmonic scattered signal as a function of protein concentration using a modified version of the Langmuir adsorption isotherm. The data obtained were checked with another technique, dynamic light scattering, using the same modified Langmuir model (MLM). While the binding constants measured by the two methods are in agreement, the number of ADH bound to each GNP obtained by the two methods varies a lot. In order to further probe this binding independent of a model fitting, we used an orthogonal fluorescence assay which measures the number of ADH bound to a GNP directly, and no model-fitting is necessary. We then used temperature dependent SHLS to measure the heat of adsorption (ΔH°) and entropy (ΔS°) for ADH–GNP corona formation. We found that the equilibrium binding constant (Kb) obtained from SHLS is of the order of 109 M−1 and the formation of the GNP–ADH corona is spontaneous with ΔG° ∼ −55 kJ mol−1. However, the adsorption is modestly endothermic, accompanied by a large increase in entropy. Stated differently, GNP–ADH corona formation is entropically driven. This is perhaps due to the tremendous disruption of the water structure at the negatively charged interface upon the arrival of the protein within the bonding distance to it. We believe that the SHLS technique is highly sensitive and reliable, at very low concentrations of both nanoparticles and proteins, for the quantitative estimation of the thermodynamic parameters of nanoparticle–protein corona formation, where many other techniques may fall short.

Spectrin, the major component of the erythrocyte membrane skeleton, is a key player in red cell biology. It has a significant role in signalling pathways, and as such knowledge of spectrin interactors becomes crucial. Here, we report the cytosolic interactome of human erythroid spectrin (ProteomeXchange id: PXD021525). This is to the best of our knowledge the first report of the interactome of human erythroid spectrin. We have further investigated the spectrin interactome under HbE-disease conditions. Our findings indicate that there is no difference in the identity of the proteins interacting with spectrin between normal and disease conditions. However, relative abundance of the interacting partners is seen to change. Very interestingly, the interacting chaperone proteins, heme-containing proteins and redox active proteins are seen to be up-regulated in HbE-disease state. This is consistent with our previous observation that the presence of oxidation prone hemoglobin variants leads to an increase of redox regulators and chaperones in the red cell proteome. Spectrin can also interact with horse radish peroxidase and oxidatively cross-link hemoglobin, which has possible implications in oxidative stress management. Since a large fraction of spectrin interacting proteins are chaperones and redox active proteins, it is possible that spectrin may have a broader role in redox regulation, especially in cases where there are unstable hemoglobin variants present.

Spectrin is a multifunctional, multi-domain protein most well known in the membrane skeleton of mature human erythrocytes. Here we review the literature on the crosstalk of the chaperone activity of spectrin with its other functionalities. We hypothesize that the chaperone activity is derived from the surface exposed hydrophobic patches present in individual "spectrin-repeat" domains and show a competition between the membrane phospholipid binding functionality and chaperone activity of spectrin. Moreover, we show that post-translational modifications such as glycation which shield these surface exposed hydrophobic patches, reduce the chaperone function. On the other hand, oligomerization which is linked to increase of hydrophobicity is seen to increase it. We note that spectrin seems to prefer haemoglobin as its chaperone client, binding with it preferentially over other denatured proteins. Spectrin is also known to interact with unstable haemoglobin variants with a higher affinity than in the case of normal haemoglobin. We propose that chaperone activity of spectrin could be important in the cellular biochemistry of haemoglobin, particularly in the context of diseases.

The functionality of electric power network are continuously challenged by dynamic and diverse disruptions. The vulnerability analysis in the context of resiliency, using complex networks has significantly modified in the past few years, enlighten valuable ideas to examine the structural, topological and constructional behavior of a power transmission network. This network having similarity with graph theoretic approach in accordance with complex graph theory. Vulnerability is assessed in this paper by evaluating betweenness and netability for topological analysis of vulnerability. Undesirable high impact low occurrence events result in disruption of a large power network as well as to the whole grid. Framework of resiliency in this paper is done in conceptual long-term basis and vulnerability assessment approach. Simulation carried out in this paper to realize the assessment of vulnerability using netability. The considered test system is standard IEEE 14 bus system. One FACTS device, namely STATCOM is employed to the system to show the improvement in the steady state bus voltage.

Hemoglobin oxidation due to oxidative stress and disease conditions leads to the generation of ROS (reactive oxygen species) and membrane attachment of hemoglobin in-vivo, where its redox activity leads to peroxidative damage of membrane lipids and proteins. Spectrin, the major component of the red blood cell (RBC) membrane skeleton, is known to interact with hemoglobin and, here this interaction is shown to increase hemoglobin peroxidase activity in the presence of reducing substrate ABTS (2', 2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid). It is also shown that in the absence of reducing substrate, spectrin forms covalently cross-linked aggregates with hemoglobin which display no peroxidase activity. This may have implications in the clearance of ROS and limiting peroxidative damage. Spectrin is found to modulate the peroxidase activity of different hemoglobin variants like A, E, and S, and of isolated globin chains from each of these variants. This may be of importance in disease states like sickle cell disease and HbE-β-thalassemia, where increased oxidative damage and free globin subunits are present due to the defects inherent in the hemoglobin variants associated with these diseases. This hypothesis is corroborated by lipid peroxidation experiments. The modulatory role of spectrin is shown to extend to other heme proteins, namely catalase and cytochrome-c. Experiments with free heme and Raman spectroscopy of heme proteins in the presence of spectrin show that structural alterations occur in the heme moiety of the heme proteins on spectrin binding, which may be the structural basis of increased enzyme activity.

Cytoskeletal drugs having enormous therapeutic potential act on the cytoskeletal components like actin, tubulin either by promoting polymerization or destabilizing the same. Here we present the interaction of the popular cytoskeletal drugs such as taxol, latrunculin and cytochalasin with spectrin, a huge protein with multi domains that forms the cytoskeletal network. Particularly, the actin binding domain of spectrin regulates the dynamics of the actin cytoskeleton. We followed the binding of these drugs to its actin binding domain and intact spectrin as well. These drugs bind with moderate affinity (Kb ∼ 104 M−1) and the interaction with actin binding domain is entropy driven and hydrophobic in nature as determined by Van’t Hoff plot. The docking studies and molecular dynamics simulations further corroborate the experimental findings. Particularly the higher binding constants in the case of latrunculin and cytochalasin to the actin binding domain of spectrin suggest the binding sites are presumably located in its actin binding domain. Communicated by Ramaswamy H. Sarma

Spectrin is a cytoskeletal protein ubiquitous in metazoan cells that acts as a liaison between the plasma membrane and the cellular interior and imparts mechanical stability to the plasma membrane. Spectrin is known to be highly dynamic, with an appreciable degree of torsional and segmental mobility. In this context, we have earlier utilized the red edge excitation shift (REES) approach to report the retention of restricted solvation dynamics and local structure in the vicinity of spectrin tryptophans on urea denaturation and loss of spectrin secondary structure. As a natural progression of our earlier work, in this work, we carried out a biophysical dissection of tryptophan solvation and rotational dynamics in spectrin and its constituent domains, in order to trace the origin of local structure retention observed in denatured spectrin. Our results show that the ankyrin binding domain (and, to a lesser extent, the β-tetramerization domain) is capable of retention of local structure, similar to that observed for intact spectrin. However, all α-chain domains studied exhibit negligible retention of local structure on urea denaturation. Such a stark chain-specific retention of local structure could originate from the fact that the β-chain domains possess specialized functions, where conservation of local (structural) integrity may be a prerequisite for optimum cellular function. To the best of our knowledge, these observations represent one of the first systematic biophysical dissections of spectrin dynamics in terms of its constituent domains and add to emerging literature on comprehensive domain-based analysis of spectrin organization, dynamics, and function.

Characterization of the nanoparticle protein corona has gained tremendous importance lately. The parameters which quantitatively establish a specific nanoparticle-protein interaction need to be measured accurately since good quality data are necessary for the elucidation of the underlying mechanism and accurate molecular dynamics simulation. Here, we have employed surface sensitive second harmonic light scattering (SHLS) for investigating the adsorption of a tetrameric protein, alcohol dehydrogenase (ADH

Hemoglobin oxidation due to oxidative stress and disease conditions leads to generation of ROS (reactive oxygen species) and membrane attachment of hemoglobin in-vivo, where its redox activity leads to peroxidative damage of membrane lipids and proteins. Spectrin, the major component of the RBC membrane skeleton, is known to interact with hemoglobin and, here this interaction is shown to increase hemoglobin peroxidase activity in the presence of reducing substrate ABTS (2’, 2’-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid). It is also shown that in the absence of reducing substrate, spectrin forms covalently cross-linked aggregates with hemoglobin which display no peroxidase activity. This may have implications in the clearance of ROS and limiting peroxidative damage. Spectrin is found to modulate the peroxidase activity of different hemoglobin variants like A, E, and S, and of isolated globin chains from each of these variants. This may be of importance in disease states like sickle cell disease and HbE-β-thalassemia, where increased oxidative damage and free globin subunits are present due to the defects inherent in the hemoglobin variants associated with these diseases. This hypothesis is corroborated by lipid peroxidation experiments. The modulatory role of spectrin is shown to extend to other heme proteins, namely catalase and cytochrome-c. Experiments with free heme and Raman spectroscopy of heme proteins in the presence of spectrin show that structural alterations occur in the heme moiety of the heme proteins on spectrin binding, which may be the structural basis of increased enzyme activity.

Spectrin, a major component of the membrane skeletal meshwork of metazoan cells, is implicated to associate with membrane domains and is known to act as a scaffold for stabilization and activation of different signalling modules. We have studied the effect of GM1 (monosialotetrahexosyl ganglioside), a well-known model ganglioside and a signalling moiety, on the interaction of non-erythroid brain spectrin with both saturated and unsaturated aminophospholipids by spectroscopic methods. We observe that GM1 modulates brain spectrin-aminophospholipid interaction to the greatest degree whereas its effect on erythroid spectrin is not as pronounced. Fluorescence quenching studies show that brain spectrin interacts with DMPC/DMPE-based vesicles with a 10-fold increased affinity in presence of very low amounts of 2% and 5% GM1, and the extent of quenching decreases progressively in presence of increasing amounts of GM1. Interaction of brain spectrin with unsaturated membrane systems of DOPC/DOPE weakens in presence GM1. Increase in the mean lifetime of the Trp residues of brain spectrin in presence of GM1 indicates change in the microenvironment of spectrin, without affecting the secondary structure of the protein significantly. Studies on pressure – area isotherm of Langmuir-Blodgett monolayer and Brewster's angle microscopy show that GM1 has an expanding effect on the aminophospholipid monolayers, and ordered regions in DMPC/DMPE mixed monolayers are formed and are stabilized at higher pressure. GM1-induced fluidization of the phospholipid membranes and probable physical contact between bulky sugar head group of GM1 and spectrin, may explain the modulatory role of GM1 on aminophospholipid interactions with nonerythroid brain spectrin.

Spectrin, the major component of the erythrocyte membrane skeleton is a key player in red cell biology. It has a significant role in signalling pathways and as such knowledge of spectrin interactors becomes crucial. Here we report the cytosolic interactome of human erythroid spectrin (ProteomeXchange id: PXD021525). This is to the best of our knowledge the first report of the interactome of human erythroid spectrin. We have further investigated the spectrin interactome under HbE disease conditions. Our findings indicate that there is no difference in the identity of the proteins interacting with spectrin between normal and disease conditions. However relative abundance of the interacting partners is seen to change. Very interestingly the interacting chaperone proteins, heme-containing proteins and redox active proteins are seen to be up-regulated in HbE disease state. This is consistent with our previous observation that presence of oxidation prone hemoglobin variants leads to an increase of redox regulators and chaperones in the red cell proteome. Spectrin can also interact with horse radish peroxidase and oxidatively crosslink hemoglobin, which has possible implications in oxidative stress management. Since a large fraction of spectrin interacting proteins are chaperones and redox active proteins, it is possible that spectrin may have a broader role in redox regulation, especially in cases where there are unstable hemoglobin variants present.

A brief overview of synchronous machine and its principle of operation have been presented in this chapter. Dynamic model of synchronous machine in a–b–c reference frame has been discussed. The theory of Park's transformation and conversion from a–b–c reference frame to d–q–o reference frame has been explained. The concept and physical interpretations of per unit (pu) representation and scaling of synchronous machine dynamic equations are presented. Rotor dynamic equations and stator algebraic equations in terms of flux–current relationship with equivalent circuit representations are discussed. Modeling of different elements of synchronous machine excitation system and state space model of IEEE Type I excitation system has been furnished in detail.

The prime objective of this book has been explored in this chapter. The problem of small-signal stability has been investigated by applying the traditional controller, PSS. A speed input single-stage PSS has been applied in the linearized model of a SMIB power system, and then, the application of PSS has been extended in a multimachine network. In both cases, investigation is carried out by studying the behavior of the critical eigenvalue without and with the application of PSS. The stability aspects of the critical eigenvalue with changes of PSS gain has also been evaluated by the root-locus analysis. This chapter also focuses on the issue of identification of the optimal site of a PSS in a multimachine power system. A new method to select the optimum location of a PSS has been proposed here. The validity of the newly proposed PSS location indicator is tested by comparing it with the methods available in existing literatures. A WSCC type 3-machine, 9-bus test system has been taken as a test case.

This chapter emphasizes on tuning and design of optimal power system controllers. Two powerful stochastic optimization methods the PSO and the GA are employed to find the optimal locations and setting parameters of the FACTS controllers: SVC and TCSC. This chapter also compares the performance of the PSO-based SVC and the PSO-based TCSC controllers with their GA-based design. The theory and method of the design of a robust TCSC controller has been explained. An H ∞ TCSC controller has been designed in an LMI framework with pole placement constraint in order to mitigate interarea oscillations in a multiarea power system network. Finally, a remote feedback control scheme has been proposed to realize a closed-loop control system in a multiarea power system.

Drug design and targeted delivery in cells serve as a flourishing area not only for scientific inquiry, owing to numerous clinical applications, but also for understanding cell interaction with exogenous materials. The membrane localization of heme and its analog hemin, one of the most biologically relevant planar organic molecule, is very important to understand the molecular mechanism of intercalation and adsorption of this cytotoxic molecule after its dissociation from proteins such as hemoglobin. Herein, we investigate the differential behavior of hemin on the soft membrane surfaces of phospholipids by synchrotron-based X-ray scattering techniques, Langmuir monolayer measurements, and molecular dynamics simulation. A continuous hemin uptake from the subphase and intercalation into and/or adsorption on to the membrane surface have been witnessed in a strong membrane surface packing-specific manner. Competitive interactions between hemin-membrane and hemin-hemin are proposed to be responsible for the critical hemin concentration. Up to the limit, a continuous hemin uptake is possible and beyond that the hemin-hemin interaction dominates, effectively reducing the hemin intercalation into the membrane. This structural model of the hemin-uptake process can be generalized to understand the localization and transport across membranes and also for the development and design of new drugs.

The paper analyses the readability of the abstracts of the articles published in different volumes of the journal, SRELS Journal of Information Management from 2011 to 2015. The paper examines the number of words; length of sentences, etc. and presents an average grade level according to readability formula. A total 301 abstracts of articles were selected during the period of 2011-2015 for this study. On the basis of these abstracts published in the journal, it is found that abstracts are made of 100 to 150 words. The results showed that the abstracts are not very easy to comprehend in terms of readability indices such as Gunning Fog index, Coleman Liau index, Flesch Kincaid Grade level, Automated Readability Index (ARI) and SMOG. From the study, it is clear that one requires 13 to 14 year education to understand the abstracts. At the end it is proposed that the abstracts should be more readable and clearer after the first reading.

Molecular chaperones are one of the key players in protein biology and as such their structure and mechanism of action have been extensively studied. However the substrate specificity of molecular chaperones has not been well investigated. This review aims to summarize what is known about the substrate specificity and substrate recognition motifs of chaperones so as to better understand what substrate specificity means in the context of molecular chaperones. Available literature shows that the majority of chaperones have broad substrate range and recognize non-native conformations of proteins depending on recognition of hydrophobic and/or charged patches. Based on these recognition motifs chaperones can select for early, mid or late folding intermediates. Another major contributor to chaperone specificity are the co-chaperones they interact with as well as the sub-cellular location they are expressed in and the inducability of their expression. Some chaperones which have only one or a few known substrates are reported. In their case the mode of recognition seems to be specific structural complementarity between chaperone and substrate. It can be concluded that the vast majority of chaperones do not show a high degree of specificity but recognize elements that signal non-native protein conformation and their substrate range is modulated by the context they function in. However a few chaperones are known that display exquisite specificity of their substrate e.g. mammalian heat shock protein 47 collagen interaction. © 2017 IUBMB Life, 69(9):647-659, 2017.

Lateral and out-of-plane organization of cholesterol and its effect on regulating the physicochemical properties of zwitterionic phospholipid model membranes have been investigated by a pressure–area isotherm study from the Langmuir monolayer, atomic force microscopy (AFM), and X-ray reflectivity (XRR) measurements from supported binary monolayer films. The systematic isotherm studies on the Langmuir monolayer of phospholipids and the subsequent extraction of excess Gibbs free energy (ΔGexc) revealed the mechanism of cholesterol interaction and the molecular cooperativeness for different arrangements in the phospholipid model membranes. We have found a critical cholesterol molar concentration (χc) up to which the lipid–cholesterol miscibility gradually increases and then further increase in the concentration leads to an inhomogeneous structure formation similar to raft structures. The thickening in the lipid acyl chain and the subsequent lowering of the lipid head group thickness up to χc are also evident...

Spectrin, the major protein component of the erythrocyte membrane skeleton has chaperone like activity and is known to bind membrane phospholipids and hemoglobin. We have probed the chaperone activity of spectrin in presence of hemoglobin and phospholipid SUVs of different compositions to elucidate the effect of phospholipid/hemoglobin binding on chaperone function. It is seen that spectrin displays a preference for hemoglobin over other substrates leading to a decrease in chaperone activity in presence of hemoglobin. A competition is seen to exist between phospholipid binding and chaperone function of spectrin, in a dose dependent manner with the greatest extent of decrease being seen in case of phospholipid vesicles containing aminophospholipids e.g. PS and PE which may have implications in diseases like hereditary spherocytosis where mutation in spectrin is implicated in its detachment from cell membrane. To gain a clearer understanding of the chaperone like activity of spectrin under in-vivo like conditions we have investigated the effect of macromolecular crowders as well as phosphorylation and glycation states on chaperone activity. It is seen that the presence of non-specific, protein and non-protein macromolecular crowders do not appreciably affect chaperone function. Phosphorylation also does not affect the chaperone function unlike glycation which progressively diminishes chaperone activity. We propose a model where chaperone clients adsorb onto spectrin's surface and processes that bind to and occlude these surfaces decrease chaperone activity.

Spectrin, the major protein of the erythrocyte membrane skeleton has canonically been thought to only serve a structural function. We have previously described a novel chaperone-like property of spectrin and also hypothesized that the chaperone activity and binding of a hydrophobic ligand, Prodan are localized in the self-association domain. Here we probe the location and molecular origin of the chaperone activity of multi-domain spectrin using a selection of individual recombinant spectrin domains, which we have characterized using intrinsic tryptophan fluorescence and CD spectroscopy to show their identity to native spectrin. Aggregation assays using insulin, ADH, α- and β-globin as well as enzyme refolding assays using alkaline phosphatase and α-glucosidase show that the chaperone activity is not only localized in the self-association domain but is a generalized property of spectrin domains. This is to our understanding, a unique feature in the case of modular multi-repeat proteins, possibly implicating that the large family of "spectrin-repeat" domain containing proteins may also have chaperone like property. Substrate selectivity of chaperone activity as evidenced by the preferential protection of α- over β-globin chains is seen; which has implications in hemoglobin diseases. Moreover, enzyme-refolding assays also indicate alternate modes of chaperone action. We propose that the molecular origin of chaperone activity resides in the surface exposed hydrophobic patches of the spectrin domains as shown by ANS (1-anilinonaphthalene-8-sulfonic acid) and Prodan (6-propionyl-2[dimethylamino]-naphthalene) binding. We also show that Prodan does indeed have a unique binding site on spectrin located at the self-association domain.

Spectrin-based proteinaceous membrane skeletal network has been found to be implicated in membrane disorders like hereditary spherocytosis (HS). HS greatly affects eryptosis via loss of membrane asymmetry which is seen to be the case in haemoglobin disorders like thalassemia and sickle cell disease as well. The biological implications of the status of membrane asymmetry are strongly correlated to spectrin interactions with aminophospholipids, e.g. PE and PS. Fluorescence and X-ray reflectivity (XRR) measurements of spectrin interactions with small unilamellar vesicles (SUVs) and cushioned bilayers of phospholipids, respectively, were studied. Both the XRR and fluorescence measurements led to the characterization of spectrin orientation on the surface of lipid bilayer of phosphatidylcholine (PC) and PC/aminophospholipid mixed membrane systems showing formation of a uniform layer of spectrin on top of the mixed phospholipid bilayer. Fluorescence studies show that spectrin interacts with PC and phosphatidylethanolamine (PE)/phosphatidylserine (PS) membranes with binding dissociation constants (K