Reactive Behavior of Ferrihydrite and Aluminic Ferrihydrite Toward the Adsorption of Arsenate

Mohapatra, Debasish,Mishra, Debaraj,Chaudhury, G. Roy,Das, R.P.,Park, Kyung-Ho 한국암반공학회 2006 Geosystem engineering Vol.9 No.2

The adsorption of arsenate (As(V)) on "ferrihydrite" prepared by two different methods; "aluminic ferrihydrite" (Fe(III)/ AI(III) molar ratio 1:1) and the stability of As(V) bearing materials were investigated. The parameters optimized for adsorption were pH, contact time, adsorbent and As(V) concentration. For leaching study four different leaching reagents (10mg C/L dissolved organic matter, 0.1M phosphate, 0.1M citrate and 0.1M oxalate) were used. The kinetics of arsenic adsorption on both type of ferrihydrites were similar with an equilibrium time of 1h; whereas, in case of aluminic ferrihydrite the equilibrium time was 3h. For aluminic ferrihydrite, maximum adsorption was found at pH 6.0. Whereas, for ferrihydrites pH 7.0 was found to be the best for As(V) adsorption. The highest As(V) adsorption capacity was shown by aluminic ferrihydrite (21.8 mg/g), followed by ferrihydrite prepared by emulsion method and ferrihydrite prepared by ordinary method (14.9 and 9.8 mg/g, respectively). In case of As(V) extraction from the loaded materials, the pH had a significant effect. In all cases, except citrate for aluminic ferrihydrite, extraction decreased with increasing pH in the range 5.0-8.0. For oxalate the iron extraction and for citrate the aluminium extraction followed the same trend as that for arsenic as a function of pH, suggesting that dissolution of these metals and consequent release of the adsorbed arsenic is one of the main mechanisms for arsenic extraction. However, for phosphate and DOM, the As(V) extraction mechanism was competition between arsenic and those anions for adsorption sites.

From In Vitro to Perioperative Vascular Tissue Engineering: Shortening Production Time by Traceable Textile-Reinforcement

Mohapatra Saurav Ranjan,Rama Elena,Melcher Christoph,Call Tobias,Al Enezy-Ulbrich Miriam Aischa,Pich Andrij,Apel Christian,Kiessling Fabian,Jockenhoevel Stefan 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: The production of tissue-engineered vascular graft (TEVG) usually involves a prolonged bioreactor cultivation period of up to several weeks to achieve maturation of extracellular matrix and sufficient mechanical strength. Therefore, we aimed to substantially shorten this conditioning time by combining a TEVG textile scaffold with a recently developed copolymer reinforced fibrin gel as a cell carrier. We further implemented our grafts with magnetic resonance imaging (MRI) contrast agents to allow the in-vitro monitoring of the TEVG’s remodeling process. METHODS: Biodegradable polylactic-co-glycolic acid (PLGA) was electrospun onto a non-degradable polyvinylidene fluoride scaffold and molded along with copolymer-reinforced fibrin hydrogel and human arterial cells. Mechanical tests on the TEVGs were performed both instantly after molding and 4 days of bioreactor conditioning. The non-invasive in vitro monitoring of the PLGA degradation and the novel imaging of fluorinated thermoplastic polyurethane (19F-TPU) were performed using 7T MRI. RESULTS: After 4 days of close loop bioreactor conditioning, 617 ± 85 mmHg of burst pressure was achieved, and advanced maturation of extracellular matrix (ECM) was observed by immunohistology, especially in regards to collagen and smooth muscle actin. The suture retention strength (2.24 ± 0.3 N) and axial tensile strength (2.45 ± 0.58 MPa) of the TEVGs achieved higher values than the native arteries used as control. The contrast agents labeling of the TEVGs allowed the monitorability of the PLGA degradation and enabled the visibility of the non-degradable textile component. CONCLUSION: Here, we present a concept for a novel textile-reinforced TEVG, which is successfully produced in 4 days of bioreactor conditioning, characterized by increased ECM maturation and sufficient mechanical strength. Additionally, the combination of our approach with non-invasive imaging provides further insights into TEVG’s clinical application.

Secure Communications for the Two-User Broadcast Channel With Random Traffic

Mohapatra, Parthajit,Pappas, Nikolaos,Lee, Jemin,Quek, Tony Q. S.,Angelakis, Vangelis IEEE 2018 IEEE transactions on information forensics and sec Vol.13 No.9

<P>In this paper, we study the stability region of the two-user broadcast channel (BC) with bursty data arrivals and security constraints. It is assumed that one of the receivers has a secrecy constraint, i.e., its packets need to be kept secret from the other receiver, which is defined based on signal to interference noise ratio. The receiver with secrecy constraint has full-duplex capability to send a jamming signal for improving its service rate. The stability region of the two-user BC with secrecy constraint is characterized for the general decoding case. Then, assuming two different decoding schemes, the respective stability regions are derived. The full-duplex operation of receiver results in self-interference, and the effect of imperfect self-interference cancelation on the stability region is also investigated. The stability region of the BC with a secrecy constraint, where the receivers do not have full duplex capability can be obtained as a special case of the results derived in this paper. In addition, the paper considers the problem of maximizing the saturated throughput of the queue for which there is no secrecy constraint under minimum service guarantees for the other queue. The results provide new insights on the effect of the secrecy constraint on the stability region of the BC. It is found that the stability region with secrecy constraint is sensitive to the degree of self-interference cancelation.</P>

Removal of Arsenic(V) from Aqueous Solutions by Using Natural Minerals

Mohapatra Debasish,Mishra Debaraj,Chaudhury G. Roy,Das R.P.,Park, Kyung-Ho The Korean Institute of Resources Recycling 2006 資源 리싸이클링 Vol.15 No.5

The removal of arsenic(V) using four different natural minerals were evaluated. Parameters like contact time, pH, adsorbent dosages, and As(V) concentration were optimized. The kinetics of adsorption was observed to be fast and reached equilibrium within 2h. As(V) adsorption on studied minerals was dependent on pH and followed a pseudo-second-order reaction model. For kaolin, maximum adsorption was found at pH 5.0. Whereas, in case of other three minerals, a pH range of 6.0-7.0 was found to be the best for As(V) adsorption. The maximum adsorption capacity (Q) was calculated by fitting Langmuir equation to the adsorption isotherms obtained under a specified condition. From the slope of best fit, the Q values were calculated to be 2.07, 2.15, 1.95 and 0.86 mg As(V)/g of bauxite, wad, iron ore and kaolin, respectively. Desorption of As(V) from loaded materials was dependent on the type of leaching reagents used. Based on the results, it was found that among the studied natural minerals, wad was the best As(V) adsorbent.

Sulfur Doping: Unique Strategy To Improve the Supercapacitive Performance of Carbon Nano-onions

Mohapatra, Debananda,Dhakal, Ganesh,Sayed, Mostafa Saad,Subramanya, Badrayyana,Shim, Jae-Jin,Parida, Smrutiranjan American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.8

<P>Recently, enhancement of the energy density of a supercapacitor is restricted by the inferior capacitance of negative electrodes, which impedes the commercial development of high-performance symmetric and asymmetric supercapacitors. This article introduces the in situ bulk-quantity synthesis of hydrophilic, porous, graphitic sulfur-doped carbon nano-onions (S-CNO) using a facile flame-pyrolysis technique and evaluated its potential applications as a high-performance supercapacitor electrode in a symmetric device configuration. The high-surface wettability in the as-prepared state enables the formation of highly suspended active conducting material S-CNO ink, which eliminates the routine use of binders for the electrode preparation. The as-prepared S-CNO displayed encouraging features for electrochemical energy storage applications with a high specific surface area (950 m<SUP>2</SUP> g<SUP>-1</SUP>), ordered mesoporous structure (∼3.9 nm), high S-content (∼3.6 at. %), and substantial electronic conductivity, as indicated by the ∼80% sp<SUP>2</SUP> graphitic carbon content. The in situ sulfur incorporation into the carbon framework of the CNO resulted in a high-polarized surface with well-distributed reversible pseudosites, increasing the electrode-electrolyte interaction and improving the overall conductivity. The S-CNOs showed a specific capacitance of 305 F g<SUP>-1</SUP>, an energy density of 10.6 W h kg<SUP>-1</SUP>, and a power density of 1004 W kg<SUP>-1</SUP> at an applied current density of 2 A g<SUP>-1</SUP> in a symmetrical two-electrode cell configuration, which is approximately three times higher than that of the pristine CNO-based device in a similar electrochemical testing environment. Even at 11 A g<SUP>-1</SUP>, the S-CNO||S-CNO device rendered an energy density (6.1 W h kg<SUP>-1</SUP>) at a deliverable power density of 5.5 kW kg<SUP>-1</SUP>, indicating a very good rate capability and power management during peak power delivery applications. Furthermore, it showed a high degree of electrochemical reversibility with excellent cycling stability, retaining ∼95% of its initial capacitance after more than 10 000 repetitive charge-discharge cycles at an applied current density of 5 A g<SUP>-1</SUP>.</P> [FIG OMISSION]</BR>

Recent Advances in ROS-Scavenging Metallic Nanozymes for Anti-Inflammatory Diseases: A Review

MOHAPATRA ADITYANARAYAN,박인규 전남대학교 의과학연구소 2023 CMJ Vol.59 No.1

Oxidative stress and dysregulated inflammatory responses are the hallmarks of inflammatory disorders, which are key contributors to high mortality rates and impose a substantial economic burden on society. Reactive oxygen species (ROS) are vital signaling molecules that promote the development of inflammatory disorders. The existing mainstream therapeutic approaches, including steroid and non-steroidal anti-inflammatory drugs, and proinflammatory cytokine inhibitors with anti-leucocyte inhibitors, are not efficient at curing the adverse effects of severe inflammation. Moreover, they have serious side effects. Metallic nanozymes (MNZs) mimic the endogenous enzymatic process and are promising candidates for the treatment of ROS-associated inflammatory disorders. Owing to the existing level of development of these metallic nanozymes, they are efficient at scavenging excess ROS and can resolve the drawbacks of traditional therapies. This review summarizes the context of ROS during inflammation and provides an overview of recent advances in metallic nanozymes as therapeutic agents. Furthermore, the challenges associated with MNZs and an outline for future to promote the clinical translation of MNZs are discussed. Our review of this expanding multidisciplinary field will benefit the current research and clinical application of metallic-nanozyme-based ROS scavenging in inflammatory disease treatment.

Effect of Cr-Rich Phase Precipitation on Magnetic and Mechanical Properties of Fe-20% Cr Alloy

Mohapatra, J. N.,Kamada, Y.,Kikuchi, H.,Kobayashi, S.,Echigoya, J.,Park, D. G.,Cheong, Y. M. IEEE 2011 IEEE transactions on magnetics Vol.47 No.10

<P>Magnetic Hysteresis Loop (MHL) and micro-Vickers hardness measurements were carried out in isothermal aged Fe-20 wt. % Cr alloy. The results were compared with the existing atom probe data at similar heat treated conditions. Coercivity and hardness of the alloy was increased and remanence of the alloy was decreased with the increase in ageing time. Such increase in the magnetic and mechanical hardness was due to the nucleation and growth of Cr rich α' phase. The size of the Cr rich α' phase precipitates were increased and the number density of the precipitates were decreased with the increase in ageing time observed by atom probe analysis. In this work a good correlation between hardness (H<SUB>v</SUB>) and coercivity (H<SUB>c</SUB>) was found with the combined effect of precipitate size (r) and number density (n). A linear relationship was found with the change in coercivity and hardness of the alloy indicating that the MHL technique would be a good Non-Destructive Evaluation (NDE) tool for the evaluation of thermal embrittlement in structural components made of Fe-Cr alloys.</P>

Comparative Study of Corner and Feature Extractors for Real-Time Object Recognition in Image Processing

Mohapatra, Arpita,Sarangi, Sunita,Patnaik, Srikanta,Sabut, Sukant The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.4

Corner detection and feature extraction are essential aspects of computer vision problems such as object recognition and tracking. Feature detectors such as Scale Invariant Feature Transform (SIFT) yields high quality features but computationally intensive for use in real-time applications. The Features from Accelerated Segment Test (FAST) detector provides faster feature computation by extracting only corner information in recognising an object. In this paper we have analyzed the efficient object detection algorithms with respect to efficiency, quality and robustness by comparing characteristics of image detectors for corner detector and feature extractors. The simulated result shows that compared to conventional SIFT algorithm, the object recognition system based on the FAST corner detector yields increased speed and low performance degradation. The average time to find keypoints in SIFT method is about 0.116 seconds for extracting 2169 keypoints. Similarly the average time to find corner points was 0.651 seconds for detecting 1714 keypoints in FAST methods at threshold 30. Thus the FAST method detects corner points faster with better quality images for object recognition.

Effects of Curing Temperature on the Optical and Charge Trap Properties of InP Quantum Dot Thin Films

Mohapatra, Priyaranjan,Dung, Mai Xuan,Choi, Jin-Kyu,Jeong, So-Hee,Jeong, Hyun-Dam Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

Highly luminescent and monodisperse InP quantum dots (QDs) were prepared by a non-organometallic approach in a non-coordinating solvent. Fatty acids with well-defined chain lengths as the ligand, a non coordinating solvent, and a thorough degassing process are all important factors for the formation of high quality InP QDs. By varying the molar concentration of indium to ligand, QDs of different size were prepared and their absorption and emission behaviors studied. By spin-coating a colloidal solution of InP QD onto a silicon wafer, InP QD thin films were obtained. The thickness of the thin films cured at 60 and $200^{\circ}C$ were nearly identical (approximately 860 nm), whereas at $300^{\circ}C$, the thickness of the thin film was found to be 760 nm. Different contrast regions (A, B, C) were observed in the TEM images, which were found to be unreacted precursors, InP QDs, and indium-rich phases, respectively, through EDX analysis. The optical properties of the thin films were measured at three different curing temperatures (60, 200, $300^{\circ}C$), which showed a blue shift with an increase in temperature. It was proposed that this blue shift may be due to a decrease in the core diameter of the InP QD by oxidation, as confirmed by the XPS studies. Oxidation also passivates the QD surface by reducing the amount of P dangling bonds, thereby increasing luminescence intensity. The dielectric properties of the thin films were also investigated by capacitance-voltage (C-V) measurements in a metal-insulator-semiconductor (MIS) device. At 60 and $300^{\circ}C$, negative flat band shifts (${\Delta}V_{fb}$) were observed, which were explained by the presence of P dangling bonds on the InP QD surface. At $300^{\circ}C$, clockwise hysteresis was observed due to trapping and detrapping of positive charges on the thin film, which was explained by proposing the existence of deep energy levels due to the indium-rich phases.

Some Device Design Considerations to Enhance the Performance of DG-MOSFETs

Mohapatra, S.K.,Pradhan, K.P.,Sahu, P.K. The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.6

When subjected to a change in dimensions, the device performance decreases. Multi-gate SOI devices, viz. the Double Gate MOSFET (DG-MOSFET), are expected to make inroads into integrated circuit applications previously dominated exclusively by planar MOSFETs. The primary focus of attention is how channel engineering (i.e. Graded Channel (GC)) and gate engineering (i.e. Dual Insulator (DI)) as gate oxide) creates an effect on the device performance, specifically, leakage current ($I_{off}$), on current ($I_{on}$), and DIBL. This study examines the performance of the devices, by virtue of a simulation analysis, in conjunction with N-channel DG-MOSFETs. The important parameters for improvement in circuit speed and power consumption are discussed. From the analysis, DG-DI MOSFET is the most suitable candidate for high speed switching application, simultaneously providing better performance as an amplifier.