Application of Artificial Neural Network to Predict the Crystallite Size and Lattice Strain of CoCrFeMnNi High Entropy Alloy Prepared by Powder Metallurgy

Cheenepalli Nagarjuna,Sheetal Kumar Dewangan,Ashutosh Sharma,Kwan Lee,홍순직,안병민 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.7

An equiatomic CoCrFeMnNi high entropy alloy (HEA) was prepared by the gas atomization process. In addition, highenergymilling was carried out to study the effects of milling parameters on the morphology and crystallographic propertiesof HEA powders. Phase identification and morphology of milled powders were observed by X-ray diffraction and scanningelectron microscopy, respectively. Both the atomized and milled powders exhibited a single-phase face-centered cubic solidsolution. The resultant crystallite size (CS) and lattice strain (LS) of milled HEAs were estimated using the WilliamsonHall method and predicted using an artificial neural network (ANN) approach. With increasing the milling time from 0 to240 min, the CS decreased from 39.7 to 6.56 nm and the LS increased from 0.25%–1.48%, respectively. Furthermore, thedeveloped ANN modeling provides an excellent method for the prediction of the CS and LS with excellent accuracies of96.25% and 93.43%, respectively.

제조공정에 따른 n형 Bi₂Te_2.85Se_0.15합금의 열전성능 평가

( C. Nagarjuna ),신동원 ( D. W. Shin ),이명원 ( M. W. Lee ),이상현 ( S. H. Lee ),홍순직 ( S. J. Hong ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.3

In this study, we have fabricated n-type Bi₂Te_2.85Se_0.15 compounds by different processing routes such as crushing, milling and mixing respectively. Subsequently, the obtained powders were consolidated by spark plasma sintering (SPS). The phase crystallinity of bulk samples were identified using X-ray diffraction technique. Powder morphology and fracture surface of bulk samples were observed using the scanning electron micros-copy (SEM). The Seebeck coefficient and electrical conductivity values were significantly increased for the milling sample than crushing and mixing samples. As a result, the maximum power factor was obtained 2.4 mW/mK², which is thrice than that of crushing process. The maximum figure of merit (ZT) of 0.77 was achieved at 400 K for the milling sample. Furthermore, relatively high hardness and density values were noticed for the different pro-cessed samples. (Received May 10, 2018; Revised May 16, 2018; Accepted May 21, 2018)

Proton therapy for reducing heart and cardiac substructure doses in Indian breast cancer patients

Sapna Nangia(Sapna Nangia ),Nagarjuna Burela(Nagarjuna Burela ),M. P. Noufal(M. P. Noufal ),Kartikeswar Patro(Kartikeswar Patro ),Manoj Gulabrao Wakde(Manoj Gulabrao Wakde ),Dayanada S. Sharma(Dayanad 대한방사선종양학회 2023 Radiation Oncology Journal Vol.41 No.2

Purpose: Indians have a higher incidence of cardiovascular diseases, often at a younger age, than other ethnic groups. This higher baseline risk requires consideration when assessing additional cardiac morbidity of breast cancer treatment. Superior cardiac sparing is a critical dosimetric advantage of proton therapy in breast cancer radiotherapy. We report here the heart and cardiac-substructure doses and early toxicities in breast cancer patients treated post-operatively with proton therapy in India’s first proton therapy center. Materials and Methods: We treated twenty breast cancer patients with intensity-modulated proton therapy (IMPT) from October 2019 to September 2022, eleven after breast conservation, nine following mastectomy, and appropriate systemic therapy, when indicated. The most prescribed dose was 40 GyE to the whole breast/chest wall and 48 GyE by simultaneous integrated boost to the tumor bed and 37.5 GyE to appropriate nodal volumes, delivered in 15 fractions. Results: Adequate coverage was achieved for clinical target volume (breast/chest wall), i.e., CTV40, and regional nodes, with 99% of the targets receiving 95% of the prescribed dose (V95% > 99%). The mean heart dose was 0.78 GyE and 0.87 GyE for all and left breast cancer patients, respectively. The mean left anterior descending artery (LAD) dose, LAD D0.02cc, and left ventricle dose were 2.76, 6.46, and 0.2 GyE, respectively. Mean ipsilateral lung dose, V20Gy, V5Gy, and contralateral breast dose (Dmean) were 6.87 GyE, 14.6%, 36.4%, and 0.38 GyE, respectively. Conclusion: The dose to heart and cardiac substructures is lower with IMPT than published photon therapy data. Despite the limited access to proton therapy at present, given the higher cardiovascular risk and coronary artery disease prevalence in India, the cardiac sparing achieved using this technique merits consideration for wider adoption in breast cancer treatment.

Influence of milling atmosphere on thermoelectric properties of p-type Bi-Sb-Te based alloys by mechanical alloying

Yoon, Suk-min,Nagarjuna, Cheenepalli,Shin, Dong-won,Lee, Chul-hee,Madavali, Babu,Hong, Soon-jik,Lee, Kap-ho The Korean Powder Metallurgy Institute 2017 한국분말재료학회지 (KPMI) Vol.24 No.5

In this study, Bi-Sb-Te thermoelectric materials are produced by mechanical alloying (MA) and spark plasma sintering (SPS). To examine the influence of the milling atmosphere on the microstructure and thermo-electric (TE) properties, a p-type Bi-Sb-Te composite powder is mechanically alloyed in the presence of argon and air atmospheres. The oxygen content increases to 55% when the powder is milled in the air atmosphere, compared with argon. All grains are similar in size and uniformly, distributed in both atmospheric sintered samples. The Seebeck coefficient is higher, while the electrical conductivity is lower in the MA (Air) sample due to a low carrier concentration compared to the MA (Ar) sintered sample. The maximum figure of merit (ZT) is 0.91 and 0.82 at 350 K for the MA (Ar) and MA (Air) sintered samples, respectively. The slight enhancement in the ZT value is due to the decrease in the oxygen content during the MA (Ar) process. Moreover, the combination of mechanical alloying and SPS process shows a higher hardness and density values for the sintered samples.

Enhanced strength and conductivity of Cu-based alloys by the addition of new elements for welding tips

송준우,유현정,Cheenepalli Nagarjuna,변지상,홍순직 대한용접·접합학회 2019 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2019 No.11

Conductive and transparent submicron polymer lens array fabrication for electrowetting applications

Hafeez, Hassan,Ryu, Heon-Yul,Paluvai, Nagarjuna Reddy,Park, Jin-Goo Informa UK (TaylorFrancis) 2018 Journal of adhesion science and technology Vol.32 No.18

<P>In this study, we have demonstrated a simple and inexpensive process to fabricate electrowetting lens arrays with various curvatures (micron to submicron) on conductive and transparent polydimethylsiloxane (PDMS) molds without additional metal layers. The microlens arrays were fabricated using one-step dual diffuser lithography process, which utilizes a pair of diffusers to diffract the incident rays of UV light at wide angles before approaching the photoresist. Dimensional control and high fill factor was achieved by just varying the exposure energy and gap between the patterns in the photomask, respectively. The patterns were replicated in conductive and transparent Ag(n)-PDMS (5-20% Ag) with 15 mu m thickness. High conductivity of 4.6 x 10(-1) S/m and high transmission efficiency of 90% was demonstrated by Ag(n)-PDMS molds. Micro-nanolens arrays fabricated by the optimized corelation were utilized to demonstrate switchable wettability behavior of water droplet at different applied voltages. The electrowetting microlens array fabrication method introduced in this work has high potential to be incorporated in optoelectronics and biomedical devices.</P>

Lumbar Transforaminal Injection of Steroids versus Platelet-Rich Plasma for Prolapse Lumbar Intervertebral Disc with Radiculopathy: A Randomized Double-Blind Controlled Pilot Study

Anuj Gupta,Harvinder Singh Chhabra,Vishwajeet Singh,Daram Nagarjuna 대한척추외과학회 2024 Asian Spine Journal Vol.18 No.1

Study Design: Double-blind randomized controlled pilot study. Purpose: The purpose of this study was to compare outcomes of steroids with autologous platelet-rich plasma (PRP) administered by lumbar transforaminal injection (LTI) in patients with lumbar radiculopathy. Overview of Literature: Degenerative disc disease of the lumbar spine is one of the most common conditions managed by spine surgeons in routine practice. Once conservative management fails, LTI is diagnostic and often therapeutic. Steroids are the gold standard drug used for LTI but have limitations and side effects. Methods: In this single-center double-blind randomized controlled pilot study, 46 patients were recruited and randomized by the lottery method. The Visual Analog Scale (VAS) for leg pain, modified Oswestry Disability Index (mODI), and Short-Form 12 (SF-12) were assessed at 1 week, 3 weeks, 6 weeks, 6 months, and 1 year. Results: Both groups were comparable in terms of demographics, preprocedure VAS scores, mODI, and SF-12 scores (p=0.52). At the 1-week follow-up, the steroid group had significantly better improvement than the PRP group (p=0.0001). At the 3-week follow-up, both groups showed comparable outcomes; however, the PRP group had better symptom improvement. At 6 weeks and 6 months, the PRP group had better outcomes (VAS, p<0.0001; ODI, p=0.02; SF-12, p=0.002). Moreover, 17 and 16 patients in the steroid and PRP groups underwent repeat LTI with steroids or surgery because of pain recurrence during follow-up. At 1 year, no difference in outcomes was observed. Conclusions: PRP may be a useful alternative to steroids for LTI in lumbar radiculopathy. Although improvement was delayed and 1-year outcomes were comparable, the 6-week and 6-month outcomes were better with PRP than with LTI. Multiple PRP injections may be beneficial because of its autologous nature. However, further studies with a larger number of participants, longer follow-up, and repeat LTIs are warranted to draw definite conclusions.

Seasonal and geographical toxicity of Indoxacarb against Helicoverpa armigera and influence of different host plants against Indoxacarb in India, 2005–2007

Basweshwar S. GHODKI,Shivcharan M. THAKARE,Mangesh P. MOHARIL,Nagarjuna G. V. RAO 한국곤충학회 2009 Entomological Research Vol.39 No.1

Indoxacarb, an oxadiazine insecticide, was evaluated for its effectiveness against Helicoverpa armigera collected from selected locations in India. Determination of Indoxacarb efficacy was done using a log-dose probit (LDP) bioassay against third instars collected from cotton (Gossypium arborium) fields near Akola, India. Monthly levels of toxicity of Indoxacarb were determined from July 2005 to March 2007. The maximum tolerance level of Indoxacarb was reported for the Amaravati strain (5.09 p.p.m.) and the minimum tolerance level for the Fatehbad strain (0.22 p.p.m.). Seasonal monitoring of Indoxacarb toxicity revealed an increased trend in tolerance from July 2005 to February 2006, which decreased from March 2006. The LC50 of Indoxacarb was 2.71 p.p.m. in July 2005 and 17.14 p.p.m. in February 2006. During 2006–007, the LC50 was 3.84 p.p.m. at the start of the season and in March 2007 it was 13.51 p.p.m. The minimum LC50 of Indoxacarb was reported for H. armigera larvae fed on Legasca spp. (1.62 p.p.m.) and the maximum LC50 was reported for H. armigera reared on chickpea (Cicer arietium) (8.45 p.p.m.). LC50 of 2.73 and 4.56 p.p.m. were reported for H. armigera fed on cotton (Gossypium arborium) and pigeonpea (Cajanus cajan), respectively.

Genetics of Indoxacarb resistance in Helicoverpa armigera (Hubner)

Basweshwar S. GHODKI,Shivcharan M. THAKARE,Mangesh P. MOHARIL,Nagarjuna G. V. RAO 한국곤충학회 2009 Entomological Research Vol.39 No.1

The present investigation was done with the aim of studying the genetics of Indoxacarb resistance. Selection of Helicoverpa armigera (Hubner) with Indoxacarb was done for eight generations to develop resistance. Reciprocal crosses between resistant and susceptible populations were made to understand the population genetics of Indoxacarb resistance in H. armigera. Generation-wise selection with Indoxacarb was evaluated for resistance development in H. armigera. The LC50 of Indoxacarb was 2.81 p.p.m. for the first selected generation, and it increased to 272.55 p.p.m. after eight selected generations, which is a 1238.86-fold resistance compared to the susceptible strain. The estimated realized heritability (h2) after eight generations of selection with Indoxacarb was 0.45. The number of generations required for a tenfold increase in LC50 (1/R) was estimated to be 2.59. The response to Indoxacarb selection in H. armigera was 0.39, the estimated selection differential (S) was 0.87, and the phenotypic standard deviation (σp) was 0.03. Reciprocal crosses between Indoxacarb resistant and susceptible strains revealed that the inheritance of Indoxacarb resistance was autosomal: neither maternal effect nor linkage was evident. The values of DLC(0.10 and 0.09) indicated completely recessive inheritance of Indoxacarb resistance.

Evaluation of Upper Tropospheric Humidity in WRF Model during Indian Summer Monsoon

Attada Raju,Prashant Kumar,Anant Parekh,K. Ravi Kumar,C. Nagaraju,J. S. Chowdary,D. Nagarjuna Rao 한국기상학회 2019 Asia-Pacific Journal of Atmospheric Sciences Vol.55 No.4

In this work, we evaluate the upper tropospherichumidity (UTH) in a regional atmospheric model in conjunction with remote sensing observations and reanalysis products during the Indian summer monsoon (ISM). We performed continuous Weather Research and Forecast (WRF) model simulations from 1st May to 1st October for every year during 2001 to 2011 at 45 km spatial resolution. The maximum UTH zones viz. Bay of Bengal, and central and north-east Indian regions are well represented inWRF model when compared to the satellite observations and European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERAI) during ISM season. Analyses found that ERAI exhibits higher magnitudes of UTH over the ISM region compared to that of satellite observations (Atmospheric Infrared Sounder:AIRS) andWRF. In terms of spatial distribution, WRF is in close agreement with satellite observations as compared to ERAI, is further supported by the pattern correlation coefficients. In addition to that, our analysis suggested that WRF model could simulate the seasonal evolution of the northward movement of maximum UTH band as in AIRS and ERAI. However, UTH variability over the equatorial Indian Ocean and western north Pacific (north of Madagascar region) is underestimated (overestimated) in the WRF model compared to the observations. Nevertheless, the model is able to represent high (low) UTH over the north Indian Ocean region during active (break) period, unable to capture the northward propagation of UTH well. This indicates that the model has considerable discrepancies in simulating UTH over the deep convective monsoon region during the ISM season. It is suggested that in order to improve the UTH representation in the model over the ISM region, it is essential to reduce biases over the equatorial and southern tropical regions. Thus, this study emphasized the variations in UTH at different time scales during monsoon season along with the credibility of remote sensing observations in WRF model.