Suraj K. Nayak

Bio: Suraj K. Nayak is an academic researcher from National Institute of Technology, Rourkela. The author has contributed to research in topics: Self-healing hydrogels & Heart rate variability. The author has an hindex of 10, co-authored 69 publications receiving 355 citations. Previous affiliations of Suraj K. Nayak include Techno India.

A Review on the Nonlinear Dynamical System Analysis of Electrocardiogram Signal.

Abstract: Electrocardiogram (ECG) signal analysis has received special attention of the researchers in the recent past because of its ability to divulge crucial information about the electrophysiology of the heart and the autonomic nervous system activity in a noninvasive manner. Analysis of the ECG signals has been explored using both linear and nonlinear methods. However, the nonlinear methods of ECG signal analysis are gaining popularity because of their robustness in feature extraction and classification. The current study presents a review of the nonlinear signal analysis methods, namely, reconstructed phase space analysis, Lyapunov exponents, correlation dimension, detrended fluctuation analysis (DFA), recurrence plot, Poincare plot, approximate entropy, and sample entropy along with their recent applications in the ECG signal analysis.

Carrageenan: A Wonder Polymer from Marine Algae for Potential Drug Delivery Applications

Abstract: Background With the advancement in the field of medical science, the idea of sustained release of the therapeutic agents in the patient's body has remained a major thrust for developing advanced drug delivery systems (DDSs). The critical requirement for fabricating these DDSs is to facilitate the delivery of their cargos in a spatio-temporal and pharmacokinetically-controlled manner. Albeit the synthetic polymer-based DDSs normally address the above-mentioned conditions, their potential cytotoxicity and high cost have ultimately constrained their success. Consequently, the utilization of natural polymers for the fabrication of tunable DDSs owing to their biocompatible, biodegradable, and non-toxic nature can be regarded as a significant stride in the field of drug delivery. Marine environment serves as an untapped resource of varied range of materials such as polysaccharides, which can easily be utilized for developing various DDSs. Methods Carrageenans are the sulfated polysaccharides that are extracted from the cell wall of red seaweeds. They exhibit an assimilation of various biological activities such as anti-thrombotic, anti-viral, anticancer, and immunomodulatory properties. The main aim of the presented review is threefold. The first one is to describe the unique physicochemical properties and structural composition of different types of carrageenans. The second is to illustrate the preparation methods of the different carrageenan-based macro- and micro-dimensional DDSs like hydrogels, microparticles, and microspheres respectively. Fabrication techniques of some advanced DDSs such as floating hydrogels, aerogels, and 3-D printed hydrogels have also been discussed in this review. Next, considerable attention has been paid to list down the recent applications of carrageenan-based polymeric architectures in the field of drug delivery. Results Presence of structural variations among the different carrageenan types helps in regulating their temperature and ion-dependent sol-to-gel transition behavior. The constraint of low mechanical strength of reversible gels can be easily eradicated using chemical crosslinking techniques. Carrageenan based-microdimesional DDSs (e.g. microspheres, microparticles) can be utilized for easy and controlled drug administration. Moreover, carrageenans can be fabricated as 3-D printed hydrogels, floating hydrogels, and aerogels for controlled drug delivery applications. Conclusion In order to address the problems associated with many of the available DDSs, carrageenans are establishing their worth recently as potential drug carriers owing to their varied range of properties. Different architectures of carrageenans are currently being explored as advanced DDSs. In the near future, translation of carrageenan-based advanced DDSs in the clinical applications seems inevitable.

Novel agar–stearyl alcohol oleogel-based bigels as structured delivery vehicles

Abstract: The present study describes the synthesis of novel bigels as delivery matrices for controlled delivery applications. The bigels were prepared by mixing agar hydrogel and stearyl alcohol oleogel in different proportions. The microscopic analysis of the bigels suggested the formation of biphasic bigels at lower proportions of oleogel and bicontinuous bigel at higher proportions. Stress relaxation study was used to analyze the mechanical properties. The viscoelastic property of the bigels was estimated by modeling the relaxation profile using Weichert model of viscoelasticity. The analysis of the electrical property of the bigels showed an increase in the impedance values as the oleogel content was increased. Further, a corresponding decrease in the electrical stability of the bigels was observed with an increase in the oleogel proportion. The analysis was prepared using (RQ)Q equivalent electrical circuit model. The ciprofloxacin hydrochloride release from the bigels was predominantly diffusion-medi...

Reinforcing effect of graphene oxide reinforcement on the properties of poly (vinyl alcohol) and carboxymethyl tamarind gum based phase-separated film.

Abstract: The current study deals with the preparation and the characterization of the PVA-CMT-GO films. The PVA-CMT film was translucent in nature and smooth to touch. The addition of GO resulted in the formation of agglomerated structures. XRD studies suggested that the incorporation of GO increased the average crystallite size. The mechanical properties of the films as determined by stress relaxation studies suggested that all the films were viscoelastic in nature. The drug release study showed a decrease in the amount of the drug release with the increase in the GO content. The PVA-CMT-GO films (without drug) showed certain degree of antimicrobial activity owing to the inherent antimicrobial property of GO. The drug loaded films also showed good antimicrobial property. It was found that the prepared films altered the cell proliferation of the human skin keratinocytes in a composition-dependent manner.

Work stress precipitates depression and anxiety in young, working women and men. Commentary

Abstract: Background. Rates of depression have been rising, as have rates of work stress. We tested the influence of work stress on diagnosed depression and anxiety in young working adults. Method. Participants were enrolled in the Dunedin study, a 1972-1973 longitudinal birth cohort assessed most recently in 2004-2005, at age 32 (n=972, 96% of 1015 cohort members still alive). Work stress (psychological job demands, work decision latitude, low work social support, physical work demands) was ascertained by interview. Major depressive disorder (MDD) and generalized anxiety disorder (GAD) were ascertained using the Diagnostic Interview Schedule (DIS) and diagnosed according to DSM-IV criteria. Results. Participants exposed to high psychological job demands (excessive workload, extreme time pressures) had a twofold risk of MDD or GAD compared to those with low job demands. Relative risks (RRs) adjusting for all work characteristics were: 1·90 [95% confidence interval (CI) 1·22-2·98] in women, and 2·00 (95 % CI 1·13-3·56) in men. Analyses ruled out the possibility that the association between work stress and disorder resulted from study members' socio-economic position, a personality tendency to report negatively, or a history of psychiatric disorder prior to labour-market entry. Prospective longitudinal analyses showed that high-demand jobs were associated with the onset of new depression and anxiety disorder in individuals without any pre-job history of diagnosis or treatment for either disorder. Conclusions. Work stress appears to precipitate diagnosable depression and anxiety in previously healthy young workers. Helping workers cope with work stress or reducing work stress levels could prevent the occurrence of clinically significant depression and anxiety.

α/β Proteins

Abstract: I wish for you, with your newfound, immense skill in protein structure analysis, to consider α/β proteins. We shall consider TIM barrels, Rossmann folds, TOPRIM domains, ATPases, and kinases. Many more examples are available than we shall cover.

Biomedical applications of biodegradable polymers

Abstract: Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. To fit functional demand, materials with desired physical, chemical, biological, biomechanical, and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Fundamental Concepts of Hydrogels: Synthesis, Properties, and Their Applications

Abstract: In the present review, we focused on the fundamental concepts of hydrogels-classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.