Variability of Sensible Heat Flux over the Bay of Bengal and its Connection to Indian Ocean Dipole Events

Ajitha Cyriac,Tarumay Ghoshal,Patel Ramkrushnbhai Shaileshbhai,Arun Chakraborty 한국해양과학기술원 2016 Ocean science journal Vol.51 No.1

The Bay of Bengal (BOB) is known to possess complex thermodynamics which show distinct seasonal patterns. Surface heat fluxes in the BOB are very much dependant on upper ocean heat exchanges and wind. Sensible heat flux (SHF) is also one among those fluxes that depends on air-sea temperature difference and wind. However, this study further proves that a strong relationship exists between barrier layer thickness (BLT) and SHF variability that has not been focussed on in earlier literatures. This study also investigates the seasonal as well as inter-annual variability of SHF and its relationship with BLT and sea surface temperature (SST) patterns in more detail with statistical analyses. It is found that both SST and BLT are responsible for the evolution of SHF signal in the BOB although their effects are spatially distributed. During the post monsoon period, freshwater induced enhanced BLT is more related to SHF than the summer time when effect of SST is found to be dominant. During Indian Ocean Dipole (IOD) years, the correlation between SHF and BLT in the eastern BOB is more pronounced compared to SHF and SST. The western BOB however is dominated by SST variations for the respective IOD phase which also contribute to SHF signals there. Northernmost BOB shows high standard deviation due to river discharge effects.

Selection of Suitable Pipe Material for New Water Distribution Network Using Analytic Hierarchy Process - A Case Study of Athivilai Village of India

Ajitha Thankanadar Thavamony,Viji Rajagopa 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2

This study was made to design a new water distribution network for the Athivilai village of Tamilnadu, India. The associated problems of the village are improper water supply for growing water requirements during the summer season. The cost, service life, and material type play an important role when designing a new network. In this study, the suitable pipe material is chosen by using Analytical Hierarchy Process. The criteria selected for Analytic Hierarchy Process include Cost, Service life, Ease of maintenance, Corrosion, Leakage, and Internal pressure. The results show that the Ductile Iron pipe ranks top position followed by High Density Polyethylene, Polyvinyl Chloride, and Galvanized iron. After selecting the pipe material, the design of water distribution network is done in EPANET 2.0 software. The results show that the diameter of pipes ranges from 40 mm to 250 mm. Since the corrosion of smaller diameter Ductile Iron pipes are faster, the High Density Polyethylene pipe which acquires the second rank can be used for diameters smaller than 80 mm. For pipes with a diameter greater than 80 mm, Ductile Iron pipes are used. Furthermore, since a continuous system of supply is designed, the pressure rises above 60 m during non peak hours which indicates that the pipes are constantly subjected to internal pressure. Both the selected pipes can withstand high internal pressure which confirms the results obtained by the Analytic hierarchy process are suitable.

Instant biosynthesis of silver nanoparticles using <i>Lawsonia inermis</i> leaf extract: Innate catalytic, antimicrobial and antioxidant activities

Ajitha, B.,Reddy, Y. Ashok Kumar,Reddy, P. Sreedhara,Suneetha, Y.,Jeon, Hwan-Jin,Ahn, Chi Won Elsevier 2016 Journal of molecular liquids Vol.219 No.-

<P><B>Abstract</B></P> <P>New and innovative strategies are of potential interest for the synthesis of silver nanoparticles (AgNPs), which are used in huge range of consumer products. The present work is focused on bio-fabrication of AgNPs in single step employing <I>Lawsonia inermis</I> and evaluation of their antimicrobial, antioxidant and catalytic properties. The prepared AgNPs are highly stable and monitored through UV–Vis spectrophotometer. X-ray diffraction (XRD) and the selected area electron diffraction (SAED) patterns proved the crystalline nature of AgNPs with face-centered cubic (fcc) geometry. Morphological images confirm the uniform distribution of spherical nanoparticles. Fourier transform infrared spectroscopy (FTIR) result expounds the functional groups of a leaf extract responsible for the bio-reduction of silver ions and their interaction between them. The synthesized AgNPs show potent catalytic activity in the degradation of anthropogenic pollutant (4-nitrophenol) by excess of NaBH<SUB>4</SUB>. The biosynthesized AgNPs seem to exhibit effective antibacterial, antifungal properties and further more possess potent antioxidant and DNA protective activities. At last, the current study illustrated the potential use of <I>L. inermis</I> as a novel source for AgNPs synthesis and their pronounced applicability in biomedical field.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Lawsonia inermis</I> is an exceptional sink for biosynthesis of silver nanoparticles. </LI> <LI> Biomolecules of leaf extract are found to play active role in AgNPs formation. </LI> <LI> Zeta potential value attested the higher stability of biosynthesized AgNPs. </LI> <LI> Potent catalytic, antimicrobial and antioxidant activities are perceived. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Side Information Extraction using Bernoulli Distribution based Deep Learning Technique for Video Transmission

Ajitha G.,SanthiPrabha I. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

One method for improving the quality of the transmission of video is video encoding. The video encoding technique must compresses the video fles which does not compromise the quality of it. Further, the technique must be suited for any type of devices and the platforms. Studies have been focusing on new video codes frameworks called DVCs (Distributed Video Codings). Prior designs have used DWTs (Discrete Wavelet Transforms) and ELMs (Extreme Learning Machines) in domainbased DVC frameworks. ELM algorithm also resulted in several defects such as poor robustness, overftting problem and poor controllability. To overcome this issue, a new hybrid SI generation scheme utilizing DWTs and BDCNNs (Bernoulli Distribution based Convolution Neural Networks) is proposed in transforming domain-based DVC frameworks. The proposed system works in three phases where the frst stage uses three-level two-dimensional DWTs and Haar wavelets extract approximates coefcients. In the second step, the SAIWCSOs (Simulated Annealing Inertia Weight-based Chicken Swarm Optimisations) technique is used to achieve detailed coefcients optimization after BDCNNs provide the approximated estimation coefcients for the present frameworks. In the third stage, level by- level IDWT techniques retrieve eventual estimated frame Side Information in the spatial domains. The efectiveness of the codec is increased by the higher SI quality. The results of the experiment demonstrate that the suggested system performs better than the current technology regarding PSNR, MSE, and RMSE. When compared to state-of-the-art approaches, the suggested method achieves maximum levels of efectiveness of 30%, 35%, and 32%, correspondingly.

Synthesis of silver nanoparticles in an eco-friendly way using <i>Phyllanthus amarus</i> leaf extract: Antimicrobial and catalytic activity

Ajitha, B.,Reddy, Y. Ashok Kumar,Jeon, Hwan-Jin,Ahn, Chi Won VSP 2018 Advanced powder technology Vol.29 No.1

<P><B>Abstract</B></P> <P>In the present study, silver nanoparticles (AgNPs) with a flower-like structure were synthesized through an easy, rapid and eco-friendly pathway using <I>Phyllanthus amarus</I> leaf extract. The obtained AgNPs were characterized using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). In addition, the antimicrobial and catalytic activities of the bio-synthesized AgNPs were carried out. Our results indicated that the concentration of the Ag precursor and the volume of the leaf extract played key roles in the formation of the flower-shaped AgNPs. Morphology study confirms the shape of the obtained bio-AgNPs as flower like structure. This study also showed the presence of clear capping layers surrounding and apparently interacting with the nanoparticles. Moreover, our studies indicated this interaction to involve bio-organic capping agents in the leaf extract. UV–Vis absorption spectra confirmed the formation of AgNPs with an optimized size. The zeta (ζ) potential of the AgNPs attests the stability of the nanoparticles. FTIR spectra provided evidence for the presence of biomolecules responsible for the reduction as well as capping of the AgNPs. Finally, the bio-synthesized AgNPs were shown to be an excellent microbial activity against the selected pathogens and enhanced catalyst of the reduction of rhodamine B.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Phyllanthus amarus</I> is an exceptional sink for biosynthesis of silver nanoparticles. </LI> <LI> Biomolecules of leaf extract are found to play an active role in AgNPs formation. </LI> <LI> Zeta potential value attested the higher stability of biosynthesized AgNPs. </LI> <LI> Excellent antimicrobial and catalytic activities were obtained in an eco-friendly way. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Design and performance analysis of smart photonic sensors for industrial applications

S Poonguzhali,Sivasangari A.,Ajitha P.,Lalithakumari S.,Sridevi A.,Danasegaran Sathish Kumar 한국물리학회 2022 Current Applied Physics Vol.39 No.-

Toxic gas has a median fatal concentration in the oxygen of much more than 200 parts per million (ppm) but far less than 2000 ppm by volume of gas. Many industries, mines and thermal plants emit perilous gases that are more harmful to our human life. The Proposed nanosensor senses the various perilous gases and averts many accidents. In this paper, a two-dimensional Photonic Crystal (2D-PhC) resonator and PhC-based poisonous gas sensor based on the hexagonal and square crystal lattice are built-in smart way. The PhCs are artificial constructs of any material with an occasional enunciation of refractive index (RI). It has effective light manipulation and it would be helpful to obtain light migration in the handling of sensing applications. The TE/TM wave transmission can shift as per the RI value of different gases in the PhCs. The wavelength variations obtained agree well with the Finite Difference Time Domain (FDTD) study, and the simulation is performed by the tool RSoft. The spectral variables such as quality factor (QF), sensitivity (Se), transmitted output power and detection limit (DL) are evaluated using the RI value over the spectrum of different toxic gases. The proposed square crystal structure have acquired a QF range of 500.6, high efficiency of 99%, and a better Se of 716.6 nm/RIU at 1502 nm. The designed hexagonal crystal structure have acquired a QF range of 165.8, high efficiency of 99%, and a better Se of 798.24 nm/RIU at 1630 nm respectively. The DL for both the proposed sensors is very low. So, the designed smart sensor helps promptly recognize the contaminated gases in several places. The proposed nanosensor is helpful in industrial safety, health care applications, aerospace, agricultural, transportation, environmental monitoring, thermal plants and mines.

Hydrogen-Bond-Assisted Controlled C–H Functionalization via Adaptive Recognition of a Purine Directing Group

Kim, Hyun Jin,Ajitha, Manjaly J.,Lee, Yongjae,Ryu, Jaeyune,Kim, Jin,Lee, Yunho,Jung, Yousung,Chang, Sukbok American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.3

<P>We have developed the Rh-catalyzed selective C–H functionalization of 6-arylpurines, in which the purine moiety directs the C–H bond activation of the aryl pendant. While the first C–H amination proceeds via the N1-chelation assistance, the subsequent second C–H bond activation takes advantage of an intramolecular hydrogen-bonding interaction between the initially formed amino group and one nitrogen atom, either N1 or N7, of the purinyl part. Isolation of a rhodacycle intermediate and the substrate variation studies suggest that N1 is the main active site for the C–H functionalization of both the first and second amination in 6-arylpurines, while N7 plays an essential role in controlling the degree of functionalization serving as an intramolecular hydrogen-bonding site in the second amination process. This pseudo-Curtin–Hammett situation was supported by density functional calculations, which suggest that the intramolecular hydrogen-bonding capability helps second amination by reducing the steric repulsion between the first installed ArNH and the directing group.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-3/ja4118472/production/images/medium/ja-2013-118472_0019.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja4118472'>ACS Electronic Supporting Info</A></P>

Effect of Substrate Temperature on Structural, Optical and Electrical Properties of Sputtered NiO-Ag Nanocrystalline Thin Films

Y. Ashok Kumar Reddy,B. Ajitha,P. Sreedhara Reddy,프라탑 렙디,이정희 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

NiO-Ag thin films were deposited on Corning 7059 glass substrates by DC reactive magnetron sputtering technique and investigated the substrate temperature (Ts) dependent properties of NiO-Ag thin films. X-ray diffraction results showed that crystalline films can be obtained at high Ts and all films have a preferred crystal growth texture with face centered cubic (fcc) structure and was also confirmed by Raman studies. The grain size, transmittance, band gap, mobility and carrier concentrations were increased with Ts. Room temperature deposited films have an average roughness around 6.9 nm where as increment of Ts resulted in increased roughness up to 14 nm with nanocrystalline morphology. The optimum substrate temperature to obtain NiO-Ag films was found to be 200°C. It was found that with increasing the Ts, resistivity of the films was significantly decreased.

Long-term Recipient and Graft Survival after Kidney Transplantation in Recipients with Hepatitis C Virus Infection

( Nae-yun Heo ),( Prowpanga Udompap ),( Ajitha Mannalithara ),( Donghee Kim ),( W. Ray Kim ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: The prevalence of hepatitis C virus (HCV) infection among kidneytransplant (KTx) recipients is higher than that in the generalpopulation. With the advent of highly effective antiviral regimensagainst HCV, the optimal management strategies for KTx recipient continue to evolve. We examine the impact of HCV infection onlong-term patient and graft survival after KTx.Methods: The UNOS OPTN database was queried for all adult KTxrecipients in USA between January, 2004 and December 2006. Apropensity score (PS) was created, which was used to select a matchingHCV-negative control for each HCV-positive recipient. The survivalanalysis was conducted to evaluate recipient and death-censored graftsurvival.Results: Out of 35,557 adult primary KTx recipients during the studyperiod, 1,470 (4.4%) were positive for anti-HCV at KTx. Overall, whencompared to HCV- recipients, HCV+ patients were more likely tobe older, male, and American African and more likely to have HLAmismatch, longer length of time on dialysis. PS matching selected1,374 HCV+ and - pairs. The Kaplan-Meier estimates for recipientsurvival at 1, 5, 10 year was 94.7%, 79.5%, and 58.2% for HCV+patients and 95.8%, 84.4%, and 66.3% in HCV- patients, respectively(p<0.01). Death-censored graft survival at 1, 5, 10 years was 94.4%,76.8%, and 57.0% in HCV+ patients and 94.0%, 81.1%, and 66.4%in HCV- recipients, respectively (p=0.15). The risk of death due toinfection was significantly higher in HCV+ than in HCV- recipients(hazard ratio [HR〕=1.64, 95% confidence interval [CI〕, 1.12-2.36).The incidence of death due to liver failure 0.23% per year amongHCV+ recipients, whereas there was no death from liver failure amongHCV- recipients. The risk of graft failure due to recurrent diseasewas higher in HCV+ than in HCV- recipients (HR=2.00; 95% CI,1.06-3.78). Multivariable Cox regression showed that HCV+ is associatedwith a higher risk of death (HR=1.50, 95% CI=1.28-1.75)and death-censored graft failure (HR=1.26, 95% CI=1.08-1.47).Conclusions: HCV infection was associated with decreased long termrecipient and graft survival. This analysis suggests that successful antiviraltreatment before or after KTx in chronic kidney disease withHCV infection may impact the improved recipient and graft survival.

The critical size of hydrogen-bonded alcohol clusters as effective Brønsted bases in solutions

Park, Sun-Young,Kim, Taeg Gyum,Ajitha, Manjaly J.,Kwac, Kijeong,Lee, Young Min,Kim, Heesu,Jung, Yousung,Kwon, Oh-Hoon The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.36

<P>The alkyl oxonium ion, which is a protonated alcohol, has long been proposed as a key reaction intermediate in alcohol dehydration. Nonetheless, the dynamics and structure of this simple but important intermediate species have not been adequately examined due to the transient nature of the oxonium ion. Here, we devised a model system for the key step in the alcohol dehydration reaction, in which a photoacid transfers a proton to alcohols of different basicity in the acetonitrile solvent. Using time-resolved spectroscopy and computation, we have found that the linkage of at least two alcohol molecules via hydrogen bonding is critical for their enhanced reactivity and extraction of the proton from the acid. This finding addresses the cooperative role of the simplest organic protic compounds, namely alcohols, in nonaqueous acid-base reactions.</P>