REGIONAL FLOOD FREQUENCY USING STATISTICAL SCALING

VARAS EDUARDO A. 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Control of phosphoric acid induced volume change in clays using fly ash

Chavali, Rama Vara Prasad,Reddy, P. Hari Prasad Techno-Press 2018 Geomechanics & engineering Vol.15 No.6

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

Hypergolicity and ignition delay study of gelled ethanolamine fuel

Jyoti, Botchu Vara Siva,Naseem, Muhammad S.,Baek, Seung Wook,Lee, Hyung Ju,Cho, Sung June Elsevier Science Inc 2017 Combustion and Flame Vol.183 No.-

<P><B>Abstract</B></P> <P>An experimental investigation on achieving hypergolicity with a critical catalyst concentration and measuring ignition delay of non-metalized and metalized gelled ethanolamine was performed with hydrogen peroxide as an oxidizer. The experimental results of using high speed camera were obtained by adopting the drop tests in this work. This study represented a sufficient repeatability of ignition delay for hypergolic bipropellant system. Gelled ethanolamine fuel (non-metalized and metalized with nano-sized metal particle substitution) with metal catalysts presented the results in hypergolicity with ignition delays of the order of 1–5ms in most of the cases, which was comparable to the existing liquid hypergolic bipropellant systems. However, the minimum ignition delay time was recorded for pure-CCAT case. Moreover, the calculated activation energy (E<SUB>vis</SUB>) for the gelled ethanolamine fuel for non-metalized and metalized systems was within the range of 0.03–0.06kJ/mole along with shear thinning behavior. Parameters such as apparent viscosity of the fuels, blended energetic particle, catalyst type along with its critical concentration using the drop impact plays an important role in studying the hypergolicity and ignition delay time of the gel bipropellant.</P>

Analysis of High-Temperature Effects on InAs∕In0.3Al0.7As∕InSb∕In0.3Al0.7As pHEMTs on Accessing RF/Analog performance: A Machine Learning Predictive Modeling

G. Lakshmi Vara Prasad,Venkatagurunatham Naidu Kollu,M. Sailaja,S. Radhakrishnan,K. Jagan Mohan,A. Kishore Reddy,G. Rajesh Chandra 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.1

In this paper, we delve into the intriguing realm of Pseudo-morphic High Electron Mobility Transistors (pHEMTs) composed of InAs∕In0.3Al0.7As∕InSb∕In0.3Al0.7As layers, utilizing Silvaco-TCAD for simulation. Our focus centers on the assessment of RF and analog electrical characteristics, with a keen eye on the high-temperature eff ects. The influence of temperature on device performance is meticulously evaluated in comparison to a reference device operating at room temperature. Traditionally, the critical parameters such as threshold voltage ( Vth ), transconductance ( gm ), and Ion∕Ioff ratio have been calculated within the temperature range spanning from 300 K to 700 K. The primary pHEMT device in our study exhibits impressive attributes, featuring a drain current of 950 mA, a threshold voltage of -1.75 V, a high transconductance ( gm ) value of 650 mS/mm, an Ion∕Ioff ratio of 1 × 106 , a transition frequency ( ft ) soaring to 790 GHz, and a maximum frequency ( fmax ) reaching a staggering 1.4 THz. However, as we traverse the temperature spectrum, our findings unveil a compelling narrative. The impact of rising temperature is unequivocal, triggering a cascade of transformations within the device. Notably, as the temperature escalates, we observe a noticeable decrease in current, a reduction in transconductance ( gm ), and a diminishing Ion∕Ioff ratio. To unravel the intricacies of these temperature-induced effects, we introduce the infusion of Machine Learning (ML) into our analysis.

An Efficient Machine Learning Model for Clinical Support to Predict Heart Disease

Rao, B.Vara Prasada,Reddy, B.Satyanarayana,Padmaja, I. Naga,Kumar, K. Ashok International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.6

Early detection can help prevent heart disease, which is one of the most common reasons for death. This paper provides a clinical support model for predicting cardiac disease. The model is built using two publicly available data sets. The admissibility and application of the the model are justified by a sequence of tests. Implementation of the model and testing are also discussed

급속압축장치에서 탄소 나노입자가 첨가된 연료 액적의 증발 및 연소 특성에 관한 실험적 연구

안형진(Hyeongjin Ahn),Botchu Vara Siva Jyoti,백승욱(Seung Wook Baek) 한국연소학회 2016 한국연소학회지 Vol.21 No.2

Evaporation and combustion characteristics of fuel droplet with carbon nanoparticle were investigated in a rapid compression machine(RCM). RCM is an experimental equipment to simulate one compression stroke of reciprocating engine. Nitrogen was charged into reaction chamber for evaporation experiment, while oxygen was charged for combustion experiment. N990 carbon black and n-heptane were used to synthesize the carbon nanofluids. Surfactant, span80, was used to make synthesis easier. The droplet pictures were taken using a high speed camera with 500 frames per second. Thermocouple, of which tip is 50 μm, was used not only to measure transient bulk temperature, but also to suspend the droplet. Reaction chamber temperature was calculated from pressure data. The evaporation rate of nanofluids was improved compared to pure fuel. The ignition delay was promoted due to the nanoparticle, but the burning rate was decreased.

A Placebo-Controlled Double-Blind Study Demonstrates the Clinical Efficacy of a Novel Herbal Formulation for Relieving Joint Discomfort in Human Subjects with Osteoarthritis of Knee

Vasu Karlapudi,Anjaneya Venkata Vara Prasad Mungara,Krishanu Sengupta,Barbara A. Davis,Siba Prasad Raychaudhuri 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.5

LI73014F2 is a novel composition prepared from extracts of Terminalia chebula fruit, Curcuma longa rhizome, and Boswellia serrata gum resin with synergistic benefit in 5-Lipoxygenase (5-LOX) inhibition. This herbal composition with strong anti-5-LOX activity exhibited significant pain relief as indicated through improvements in weight-bearing capacity in a monosodium iodoacetate-induced osteoarthritis (OA) model of Sprague–Dawley rats. A 90-day randomized, placebo-controlled double-blind study evaluates the clinical efficacy and tolerability of LI73014F2 in the management of symptoms of OA of the knee (Clinical Trial Registration No. CTRI/2014/01/004338). Subjects, (n = 105), were randomized into three groups: placebo (n = 35), 200 mg/day of LI73014F2 (n = 35), and 400 mg/day of LI73014F2 (n = 35). All study participants were evaluated for pain and physical function by using standard tools, that is, Visual Analog Scale, Lequesne's Functional Index, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at the baseline (day 0) and on day 14 ± 3, 30 ± 3, 60 ± 3, and at the end of the study (day 90 ± 3). In addition, routine examinations on biochemical parameters in serum, urine, and hematological parameters were conducted on each visit to assess the safety of the study material. At the end of the trial period, LI73014F2 conferred significant pain relief, improved physical function, and quality of life in OA patients. In conclusion, preclinical and clinical data together strongly suggest that the herbal formulation LI73014F2 is a safe and effective intervention for management of joint discomfort, demonstrating efficacy as early as 14 days.

Phytogenic silver nanoparticles (Alstonia scholaris) incorporated with epoxy coating on PVC materials and their biofilm degradation studies

Supraja, Nookala,Tollamadugu, Naga Venkata Krishna Vara Prasad,Adam, S. Techno-Press 2016 Advances in nano research Vol.4 No.4

The advantages of nano-scale materials (size 1-99 nm in at least in one dimension) could be realized with their potential applications in diversified avenues. Herein, we report for the first time on the successful synthesis of homogeneous epoxy coatings containing phytogenic silver nanoparticles (Ag) on PVC and glass substrates by room-temperature curing of fully mixed epoxy slurry diluted by acetone. Alstonia scholaris bark extract was used to reduce and stabilize the silver ions. The surface morphology and mechanical properties of these coatings were characterized using the techniques like, UV-Vis (UV-Visible) spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FT-IR), Epifluorescence microscopy and scanning electron microscopy (SEM). The effect of incorporating Ag nanoparticles on the biofilm (scale) resistant epoxy-coated PVC was investigated by total viable counts ($CFU/cm^2$) from epoxy coating from (Initial) $1^{st}$ day to $25^{th}$ days. The phytogenic Ag nanoparticles were found to be significantly improving the microstructure of the coating matrix and thus enhanced the anti-biofilm performance of the epoxy coating. In addition, the antimicrobial mechanism of Ag nanoparticles played an important role in improving the anti-biofilm performance of these epoxy coatings.

Platinum-based nanocages with subnanometer-thick walls and well-defined, controllable facets

Zhang, Lei,Roling, Luke T.,Wang, Xue,Vara, Madeline,Chi, Miaofang,Liu, Jingyue,Choi, Sang-Il,Park, Jinho,Herron, Jeffrey A.,Xie, Zhaoxiong,Mavrikakis, Manos,Xia, Younan American Association for the Advancement of Scienc 2015 Science Vol.349 No.6246

<P><B>Etching platinum nanocage catalysts</B></P><P>Although platinum is an excellent catalyst for the oxygen reduction reaction that occurs in fuel cells, its scarcity continues to drive efforts to improve its utilization. Zhang <I>et al.</I> made nanocages of platinum by coating palladium nanocrystals with only a few layers of platinum and then etching away the palladium core (see the Perspective by Strasser). Platinum nanocages made using nanoscale octahedra and cubes of palladium displayed different catalytic activity for the oxygen reduction reaction.</P><P><I>Science</I>, this issue p. 412; see also p. 379</P><P>A cost-effective catalyst should have a high dispersion of the active atoms, together with a controllable surface structure for the optimization of activity, selectivity, or both. We fabricated nanocages by depositing a few atomic layers of platinum (Pt) as conformal shells on palladium (Pd) nanocrystals with well-defined facets and then etching away the Pd templates. Density functional theory calculations suggest that the etching is initiated via a mechanism that involves the formation of vacancies through the removal of Pd atoms incorporated into the outermost layer during the deposition of Pt. With the use of Pd nanoscale cubes and octahedra as templates, we obtained Pt cubic and octahedral nanocages enclosed by {100} and {111} facets, respectively, which exhibited distinctive catalytic activities toward oxygen reduction.</P>

Effect of citrate coated silver nanoparticles on biofilm degradation in drinking water PVC pipelines

Nookala, Supraja,Tollamadugu, Naga Venkata Krishna Vara Prasad,Thimmavajjula, Giridhara Krishna,Ernest, David Techno-Press 2015 Advances in nano research Vol.3 No.2

Citrate ion is a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radiolytic synthetic methods. The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of citrate coated Ag nanoparticles (CAgNPs) are scant. Herein, we have isolated biofilm causative bacteria and fungi from drinking water PVC pipe lines. Stable CAgNPs were prepared and the formation of CAgNPs was confirmed by UV-visible spectroscopic analysis and recorded the localized surface plasmon resonance of CAgNPs at 430 nm. Fourier transform infrared spectroscopic analysis revealed C=O and O-H bending vibrations due to organic capping of silver responsible for the reduction and stabilization of the CAgNPs. X-ray diffraction micrograph indicated the face centered cubic structure of the formed CAgNPs, and morphological studies including size (average size 50 nm) were carried out using transmission electron microscopy. The hydrodynamic diameter (60.7 nm) and zeta potential (-27.6 mV) were measured using the dynamic light scattering technique. The antimicrobial activity of CAgNPs was evaluated (in vitro) against the isolated fungi, Gram-negative and Gram-positive bacteria using disc diffusion method and results revealed that CAgNPs with 170ppm concentration are having significant antimicrobial effects against an array of microbes tested.