RETRACTED ARTICLE: Spatio–temporal attention based real-time environmental monitoring systems for landslide monitoring and prediction

M. Vijay Sekhar Babu,N. Ashokkumar,Anjali Joshi,Pallavi Sagar Deshpande,Ismail Keshta,Renato R. Maaliw III 대한공간정보학회 2024 Spatial Information Research Vol.32 No.2

The Publisher has retracted this article in agreement with the Editor-in-Chief. The article was submitted to be part of a guest-edited issue. An investigation by the publisher found a number of articles, including this one, with a number of concerns, including but not limited to compromised editorial handling and peer review process, inappropriate or irrelevant references or not being in scope of the journal or guest-edited issue. Based on the investigation's fndings the publisher, in consultation with the Editor-in-Chief therefore no longer has confdence in the results and conclusions of this article. Authors N. Ashokkumar, Anjali Joshi, Pallavi Sagar Deshpande and Renato R. Maaliw III disagree with this retraction. Author M. Vijay Sekhar Babu has not responded to correspondence regarding this retraction. The publisher has been unable to obtain a current email address for author Ismail Keshta. The online version of this article contains the full text of the retracted article as Supplementary Information.

Gold nanoparticle-embedded DNA thin films for ultraviolet photodetectors

Mitta, Sekhar Babu,Reddeppa, Maddaka,Vellampatti, Srivithya,Dugasani, Sreekantha Reddy,Yoo, Sanghyun,Lee, Seungwoo,Kim, Moon-Deock,Ha Park, Sung Elsevier 2018 Sensors and actuators. B Chemical Vol.275 No.-

<P><B>Abstract</B></P> <P>Although DNA (low-cost, highly transparent, low optical loss, biodegradable, non-toxic, and highly flexible) and gold nanoparticles (Au NPs, exhibiting interband transition and localized surface plasmon resonance) have been intensively studied, DNA with Au NPs in photodetectors is rarely discussed. Here, we constructed salmon DNA (SDNA) thin films and incorporated Au NPs to demonstrate efficient and high-performance UV photodetectors. The Au NP-embedded SDNA thin films were characterized with UV–vis absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and conductivity measurements in order to understand their physical and chemical properties. The FTIR and XPS measurements elucidated how Au NPs become embedded in SDNA, through analysis of chemical binding and chemical composition. A current increase was observed under UV illumination when performing conductivity measurements. In addition, photovoltage measurements were conducted to investigate the significance of photoresponse and retention characteristics. The density of <I>d</I>-band electrons in Au NPs and the charge carriers in SDNA were observed to increase under UV illumination, followed by a significantly enhanced UV photoresponse. From our observations, the photovoltage displayed a flat response over time, which indicated their stability, durability, and high Au NP retention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DNA thin films incorporated with Au NPs are fabricated to demonstrate efficient and high-performance UV photodetectors. </LI> <LI> The Au NP-embedded SDNA thin films are characterized in order to understand their physical and chemical properties. </LI> <LI> The FTIR and XPS elucidate how Au NPs become embedded in SDNA,through analysis of chemical binding and chemical composition. </LI> <LI> Photovoltage measurements are conducted to investigate the significance of photoresponse and retention characteristics. </LI> <LI> Photovoltage response indicates the stability, durability, and high Au NP retention. </LI> </UL> </P>

Si/ZnO heterostructures for efficient diode and water-splitting applications

Mitta, Sekhar Babu,Murahari, Prashantha,Nandanapalli, Koteeswara Reddy,Mudusu, Devika,Karuppannan, Ramesh,Whang, Dongmok Elsevier 2018 International journal of hydrogen energy Vol.43 No.33

<P><B>Abstract</B></P> <P>We have developed thin zinc oxide (ZnO) layers protected highly conductive p-type silicon (Si) electrodes and investigated their diode and photoanode characteristics. ZnO layers have been deposited on the glass as well as p-Si substrates at a temperature of 400 °C by pulsed spray pyrolysis method. The crystal structure, surface morphology, and phase purity of the layers along with electrical characteristics of the heterostructures were investigated. Finally, the photocatalytic water oxidation performance of the ZnO/Si structures was studied in an alkaline electrolyte solution (pH = 10). The as-grown devices exhibited excellent diode characteristics with a turn-on voltage of 4.5 V, and applied bias-voltage dependent carrier transport mechanisms. As compared to bare Si, ZnO coated Si-based PEC devices showed good stability and durability along with very low onset potential of 0.07 V versus Ag/AgCl.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Si/ZnO heterostructures are developed and investigated. </LI> <LI> Structures possess significant diode and PEC properties. </LI> <LI> As compared to bare Si, good photoanodes stability and durability are observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Ultrathin ZnO layers coated Si electrodes prepared by pulsed spray pyrolysis. These heterostructures exhibited excellent p-n junction diode characteristics along with good stability as well as durability as photoanodes in an alkaline electrolyte.</P> <P>[DISPLAY OMISSION]</P>

Electromagnetic and optical characteristics of Nb⁵⁺-doped double-crossover and salmon DNA thin films

Mitta, Sekhar Babu,Dugasani, Sreekantha Reddy,Jung, Soon-Gil,Vellampatti, Srivithya,Park, Tuson,Park, Sung Ha IOP 2017 Nanotechnology Vol.28 No.40

<P>We report the fabrication and physical characteristics of niobium ion (Nb<SUP>5+</SUP>)-doped double-crossover DNA (DX-DNA) and salmon DNA (SDNA) thin films. Different concentrations of Nb<SUP>5+</SUP> ([Nb<SUP>5+</SUP>]) are coordinated into the DNA molecules, and the thin films are fabricated via substrate-assisted growth (DX-DNA) and drop-casting (SDNA) on oxygen plasma treated substrates. We conducted atomic force microscopy to estimate the optimum concentration of Nb<SUP>5+</SUP> ([Nb<SUP>5+</SUP>]<SUB>O</SUB>?=?0.08 mM) in Nb<SUP>5+</SUP>-doped DX-DNA thin films, up to which the DX-DNA lattices maintain their structures without deformation. X-ray photoelectron spectroscopy (XPS) was performed to probe the chemical nature of the intercalated Nb<SUP>5+</SUP> in the SDNA thin films. The change in peak intensities and the shift in binding energy were witnessed in XPS spectra to explicate the binding and charge transfer mechanisms between Nb<SUP>5+</SUP> and SDNA molecules. UV-visible, Raman, and photoluminescence (PL) spectra were measured to determine the optical properties and thus investigate the binding modes, Nb<SUP>5+</SUP> coordination sites in Nb<SUP>5+</SUP>-doped SDNA thin films, and energy transfer mechanisms, respectively. As [Nb<SUP>5+</SUP>] increases, the absorbance peak intensities monotonically increase until ∼[Nb<SUP>5+</SUP>]<SUB>O</SUB> and then decrease. However, from the Raman measurements, the peak intensities gradually decrease with an increase in [Nb<SUP>5+</SUP>] to reveal the binding mechanism and binding sites of metal ions in the SDNA molecules. From the PL, we observe the emission intensities to reduce them at up to ∼[Nb<SUP>5+</SUP>]<SUB>O</SUB> and then increase after that, expecting the energy transfer between the Nb<SUP>5+</SUP> and SDNA molecules. The current–voltage measurement shows a significant increase in the current observed as [Nb<SUP>5+</SUP>] increases in the SDNA thin films when compared to that of pristine SDNA thin films. Finally, we investigate the temperature dependent magnetization in which the Nb<SUP>5+</SUP>-doped SDNA thin films reveal weak ferromagnetism due to the existence of tiny magnetic dipoles in the Nb<SUP>5+</SUP>-doped SDNA complex.</P>

Solution-processed Au@rGO/GaN nanorods hybrid-structure for selfpowered UV, visible photodetector and CO gas sensors

MADDAKAREDDEPPA,Sekhar Babu Mitta,T. Chandrakalavathi,박병권,G. Murali,R. Jeyalakshmi,김송강,박성하,김문덕 한국물리학회 2019 Current Applied Physics Vol.19 No.8

Although metal nanoparticles (NPs) have been widely reported, Au NPs functionalized reduced graphene oxide (rGO)/GaN nanorods (NRs) for multi-functional applications are rarely discussed. The rGO is a well known transparent electrode and has been considering an alternative electrode to ITO in the current optoelectronic community. In this work, Au NPs functionalized rGO (Au@rGO)/GaN NRs hybrid structure probed for photodetector and CO gas sensing applications. The hybrid structure was characterized by scanning electron microscopy, transmission electron microscope, current-voltage characteristics, photo conductivity, and gas sensor measurements. The Au@rGO/GaN NRs showed higher photoresponsivity (λ=382 nm, 516 nm) compared to rGO/GaN NRs at room temperature. The rising and falling times of Au@rGO/GaN NRs are faster than that of rGO/GaN NRs. The hybrid structure Au@rGO/GaN NRs exhibited high CO gas response compared to rGO/GaN NRs at room temperature (∼38% to the 20 ppm). Au NPs played an important role in terms of electronic and chemical changes in the hybrid structure for improving both photodetectors the CO gas response. Such a multifunctional hybrid device is an interest of various room temperature applications.

An Efficient Control Strategy Based Multi Converter UPQC using with Fuzzy Logic Controller for Power Quality Problems

Paduchuri. Chandra Babu,Subhransu Sekhar Dash,C. Subramani,S. Harish Kiran 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

A custom power device provides an integrated solution to the present problems that are faced by the utilities and power distribution. In this paper, a new controller is designed which is connected to a multiconverter unified power quality conditioner (MC-UPQC) for improving the power quality issues adopted modified synchronous reference frame (MSRF) theory with Fuzzy logic control (FLC) technique. This newly designed controller is connected to a source in order to compensate voltage and current in two feeders. The expanded concept of UPQC is multi converter-UPQC; this system has a two-series voltage source inverter and one shunt voltage source inverter connected back to back. This configuration will helps mitigate any type of voltage / current fluctuations and power factor correction in power distribution network to improve power quality issues. In the proposed system the power can be conveyed from one feeder to another in order to mitigate the voltage sag, swell, interruption and transient response of the system. The control strategies of multi converter-UPQC are designed based on the modified synchronous reference frame theory with fuzzy logic controller. The fast dynamics response of dc link capacitor is achieved with the help of Fuzzy logic controller. Different types of fault conditions are taken and simulated for the analysis and the results are compared with the conventional method. The relevant simulation and compensation performance analysis of the proposed multi converter-UPQC with fuzzy logic controller is performed.

Streptavidin bound DNA open tube and Zn2+-doped DNA open lattice

Srivithya Vellampatti,Sekhar Babu Mitta,김장아,황태현,레디,김태성,박성하 한국물리학회 2015 Current Applied Physics Vol.15 No.8

DNA is one of the most promising molecules for use in nanotechnology because it has a nanoscale size and also has the ability for self-assembly. In this paper, we discuss the use of free-solution growth for a 1D DNA open tube (OT) and substrate-assisted growth for a 2D open lattice (OL), which can both achieve similar design schemes.We introduced biotinylated OT and OL, which can be bound with streptavidin for visualization, to verify via atomic force microscopy that dimensional structures have in fact been formed. Additionally the coverage ratio controlled by the concentration of the DNA monomer was analyzed to understand the lattice growth on the substrate. The DNA lattices were observed to start growing on the substrate at a concentration of around 1 nM (threshold) and to achieve full coverage at 10 nM (saturation concentration). Finally, the Raman spectra and the currentevoltage characteristics of Zn2+-doped OLs were obtained in order to demonstrate the feasibility of using such methods to produce useful materials for nanodevices and biosensors. As [Zn2+] increases above the critical value of 0.5 mM, the Raman peaks gradually decrease. The resistance decreases up to the critical value of [Zn2+], and then decreases [Zn2+] continues to increase.

DNA-CTMA functionalized GaN surfaces for NO₂ gas sensor at room temperature under UV illumination

Reddeppa, Maddaka,Mitta, Sekhar Babu,Park, Byung-Guon,Kim, Song-Gang,Park, Sung Ha,Kim, Moon-Deock Elsevier 2019 ORGANIC ELECTRONICS Vol.65 No.-

<P><B>Abstract</B></P> <P>Considering the power consumption and safety risks in the presence of combustible gases, sensor operation at room temperature (RT∼28 °C) has drawn much interest in recent days. Different strategies have been found to meet the effective sensor performance at RT. Here, we report a riveting combination of DNA‒CTMA/GaN (DGaN) hybrid structure for high-sensitive NO<SUB>2</SUB> gas sensor at RT. The surface modifications are caused by the functional groups of DNA‒CTMA interactions with GaN. The XPS studies reveal that the native oxides of GaN surface are binding with the functional groups of DNA‒CTMA. The DGaN hybrid structure display higher response to various concentrations (100–10 ppm) of NO<SUB>2</SUB> compared to the pristine GaN film. The effect of UV illumination on NO<SUB>2</SUB> gas sensing performance of DGaN is also manifested, and the response of the sensor is enhanced under UV illumination in comparison with those of dark condition. From our observations, the amine groups and the negatively charged hydroxyl groups in DNA‒CTMA helps for the higher response of gas sensor by the hybrid structure which makes them a good candidate for high-response NO<SUB>2</SUB> gas sensors at RT.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel DNA-CTMA/GaN structure for NO<SUB>2</SUB> gas sensor. </LI> <LI> DNA-CTMA/GaN hybrid structure working at room temperature. </LI> <LI> The response of sensor is superior under UV illumination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

3-Input/1-Output Logic Implementation Demonstrated by DNA Algorithmic Self-Assembly

Cho, Hyunjae,Mitta, Sekhar Babu,Song, Yongwoo,Son, Junyoung,Park, Suyoun,Ha, Tai Hwan,Park, Sung Ha American Chemical Society 2018 ACS NANO Vol.12 No.5

<P>Although structural DNA nanotechnology is a well-established field, computations performed using DNA algorithmic self-assembly is still in the primitive stages in terms of its adaptability of rule implementation and experimental complexity. Here, we discuss the feasibility of constructing an <I>M</I>-input/<I>N</I>-output logic gate implemented into simple DNA building blocks. To date, no experimental demonstrations have been reported with <I>M</I> > 2 owing to the difficulty of tile design. To overcome this problem, we introduce a special tile referred to as an operator. We design appropriate binding domains in DNA tiles, and we demonstrate the growth of DNA algorithmic lattices generated by eight different rules from among 256 rules in a 3-input/1-output logic. The DNA lattices show simple, linelike, random, and mixed patterns, which we analyze to obtain errors and sorting factors. The errors vary from 0.8% to 12.8% depending upon the pattern complexity, and sorting factors obtained from the experiment are in good agreement with simulation results within a range of 1-18%.</P> [FIG OMISSION]</BR>

Aptamer-conjugated DNA nano-ring as the carrier of drug molecules

Srivithya, Vellampatti,Roun, Heo,Sekhar Babu, Mitta,Jae Hyung, Park,Sung Ha, Park IOP 2018 Nanotechnology Vol.29 No.9

<P>Due to its predictable self-assembly and structural stability, structural DNA nanotechnology is considered one of the main interdisciplinary subjects encompassing conventional nanotechnology and biotechnology. Here we have fabricated the mucin aptamer (MUC1)˗conjugated DNA nano˗ring intercalated with doxorubicin (DNR<SUB>A</SUB>˗DOX) as potential therapeutics for breast cancer. DNR<SUB>A</SUB>˗DOX exhibited significantly higher cytotoxicity to the MCF˗7 breast cancer cells than the controls, including DOX alone and the aptamer deficient DNA nano˗ring (DNR) with doxorubicin. Interactions between DOX and DNR<SUB>A</SUB> were studied using spectrophotometric measurements. Dose-dependent cytotoxicity was performed to prove that both DNR and DNR<SUB>A</SUB> were non-toxic to the cells. The drug release profile showed a controlled release of DOX at normal physiological pH 7.4, with approximately 61% released, but when exposed to lysosomal of pH 5.5, the corresponding 95% was released within 48 h. Owing to the presence of the aptamer, DNR<SUB>A</SUB>˗DOX was effectively taken up by the cancer cells, as confirmed by confocal microscopy, implying that it has potential for use in targeted drug delivery.</P>