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Novel NiWO<sub>4</sub> nanoberries morphology effect on photoelectrochemical properties
Babu, Eadi Sunil,Rani, B. Jansi,Ravi, G.,Yuvakkumar, R.,Guduru, Ramesh K.,Ganesh, V.,Kim, Sungjin Elsevier 2018 Materials letters Vol.220 No.-
<P><B>Abstract</B></P> <P>We report a novel method to synthesis NiWO<SUB>4</SUB> nanoberries and their morphology dependent photoelectrochemical properties. XRD result revealed monoclinic wolframite NiWO<SUB>4</SUB> structure formation. FESEM and TEM showed average particle and nanoberries size of 4 and 50 nm respectively. Raman active stretching W–O vibration mode at 889 cm<SUP>−1</SUP>, PL blue green emission of intrinsic WO<SUB>6</SUB> <SUP>6−</SUP> complex with double emission center (3T<SUB>1u</SUB>-1A<SUB>1g</SUB>) and FTIR spectrum confirmed NiWO<SUB>4</SUB> formation with a calculated band gap of 2.86 eV. The much higher photocurrent of 0.03 mA/cm<SUP>2</SUP> was obtained at 0 V potential under visible light due to higher band gap (2.86 eV) of nanoberries morphology which led to efficient light absorption and increase in electron and hole separations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel synthesis of NiWO<SUB>4</SUB> nanoberries morphology. </LI> <LI> Higher photocurrent of 0.03 mA/cm<SUP>2</SUP> due to higher band gap 2.86 eV. </LI> <LI> Nanoberries morphology led to absorption, increase electron hole separations. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Graphical abstract clearly shows the schematic representation of nanoberries formation which is evident that the effect of surfactant for the formation of a big berry contains number of small berries.</P> <P>[DISPLAY OMISSION]</P>
Zinc oxide nanotips growth by controlling vapor deposition on substrates
Babu, Eadi Sunil,Saravanakumar, B.,Ravi, G.,Yuvakkumar, R.,Ganesh, V.,Guduru, Ramesh K.,Kim, Sungjin Springer-Verlag 2018 Journal of materials science Materials in electron Vol.29 No.8
<P>ZnO nanotips structure fabrication was undertaken through controlled growth by chemical vapor deposition (CVD) method. Substrate position and deposition time role was investigated systematically by controlling the parameters such as temperature, flow rate, and growth pressure. The obtained result showed that ZnO nanorods undergo a sharp regrowth process with increase in ZnO vapor availability in the CVD reactor. The surface morphology and structural properties were investigated by using field-emission scanning electron microscopy and X-ray diffraction (XRD) techniques. The grown nanostructures were used for gas sensor fabrication to detect and to study the sensitivity effects of H-2 and CO.</P>
Yonghyun Kim,V. Ramesh Babu,Daniel T. Thangadurai,K.S.V. krishna Rao,Hyeongrae Cha,김창대,주우홍,이용일 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.2
Copolymeric silver nanocomposite hydrogels were synthesized by using acryloyl phenylalanine (APA), N'-isopropylacrylamide (NIPAM) and crosslinked by N,N-methylene bisacrylamide (MBA) via radical redox polymerization. Present study allows entrapping silver nanoparticles into hydrogel networks. UV-visible spectroscopy and X-ray diffraction (XRD) studies confirmed the formation of silver nanoparticles in hydrogel matrix. 11% of weight loss difference between hydrogel and silver nanocomposite hydrogel is clearly indicates the formation and silver nanoparticles by thermo-gravimetrical analysis. The order of swelling capacity values of hydrogels and silver nanocmposite hydrogels were found to be in the order of placebo copolymeric hydrogel >Ag-copolymeric silver nanocomposite hydrogels. The particle size of silver nanoparticles was analysed and are in the range of 5 - 10 nm which has been confirmed by transmission electron microscopy (TEM) as well as particle size analysis. The silver anocomposite hydrogel has shown very good antibacterial activity on gram-positive and gram-negative bacteriocides.
Stimuli-Sensitive Poly(NIPA-co-APA) Hydrogels for the Controlled Release of Keterolac Tromethamine
Kim, Yonghyun,Babu, V. Ramesh,Rao, K.S.V. Krishna,Lim, Jae-Min,Thangadurai, T. Daniel,Lee, Yong-Ill Korean Chemical Society 2014 대한화학회지 Vol.58 No.1
The pH sensitive hydrogels composed of N-isopropylacrylamide (NIPA) and acryloyl phenylalanine (APA) were prepared by redox polymerization using N,N'-methylenebisacrylamide (MBA) as a crosslinker. Anti-inflammatory and analgesic agent, Keterolac Tromethamine (KT), was loaded successfully into poly(NIPA-co-APA) copolymeric hydrogels by swelling equilibrium method. To understand the nature of drug in the polymeric matrix, the newly synthesized drug loaded poly(NIPA-co-APA) copolymeric hydrogels were characterized by using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The scanning electron microscopy (SEM) technique result indicates the spherical smooth surface of the hydrogels. The drug (KT) releasing nature of the poly(NIPA-co-APA) hydrogels was studied in pH 1.2 and 7.4. Effects of drug loading, crosslinking agent, pH and the ionic strength of the external medium on swelling of hydrogels were also investigated.
Cha, Hyeong-Rae,Babu, V. Ramesh,Rao, K.S.V. Krishna,Kim, Yong-Hyun,Mei, Surong,Joo, Woo-Hong,Lee, Yong-Ill Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.10
New silver nanoparticle (AgNP)-loaded amino acid based hydrogels were synthesized successfully from poly (vinyl alcohol) (PVA) and poly(acryl amide-co-acryloyl phenyl alanine) (PAA) by redox polymerization. The formation of AgNP in hydrogels was confirmed by using a UV-Vis spectrophotometer and XRD. The structure and morphology of silver nanocomposite hydrogels were studied by using a scanning electron microscopy (SEM), which demonstrated scattered nanoparticles, ca. 10-20 nm. Thermogravimetric analysis revealed large differences of weight loss (i.e., 48%) between the prestine hydrogel and silver nanocomposite. The antibacterial studies of AgNP-loaded PAA (Ag-PAA) hydrogels was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. These Ag-PAA hydrogels showed significant activities against all the test bacteria. Newly developed hydrogels could be used for medical applications, such as artificial burn dressings.
Hyeong-Rae Cha,V. Ramesh Babu,K. S. V. Krishna Rao,Yong-Hyun Kim,Surong Mei,주우홍,이용일 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.10
New silver nanoparticle (AgNP)-loaded amino acid based hydrogels were synthesized successfully from poly (vinyl alcohol) (PVA) and poly(acryl amide-co-acryloyl phenyl alanine) (PAA) by redox polymerization. The formation of AgNP in hydrogels was confirmed by using a UV-Vis spectrophotometer and XRD. The structure and morphology of silver nanocomposite hydrogels were studied by using a scanning electron microscopy (SEM), which demonstrated scattered nanoparticles, ca. 10-20 nm. Thermogravimetric analysis revealed large differences of weight loss (i.e., 48%) between the prestine hydrogel and silver nanocomposite. The antibacterial studies of AgNP-loaded PAA (Ag-PAA) hydrogels was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. These Ag-PAA hydrogels showed significant activities against all the test bacteria. Newly developed hydrogels could be used for medical applications, such as artificial burn dressings.
H. Joy Hoskeri,V. Krishna,B. Vinay Kumar,A. H. Shridar,K. Ramesh Babu,M. S. Sudarshana 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.10
The prophylactic effects of oleanolic acid (OA) isolated from chloroform extract (CE) of Flaveria trinervia against ethanol induced liver toxicity was investigated using rats. CE and OA at three different doses were tested by administering orally to the ethanol treated animals during the last week of the 7 weeks study. Silymarin was used as the standard reference. The substantially elevated serum enzymatic levels of serum glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase and bilirubin in ethanol treated animals were restored towards normalcy by treatment of CE and OA. In vivo antioxidant and in vitro free radical scavenging activities were also positive for all the three concentrations of CE and OA. However, OA at 150 mg/kg showed significant activity when compared to the other two doses. Biochemical observations in support with histopathological examinations revealed that CE and OA possess hepatoprotective action against ethanol induced hepatotoxicity in rats.
Kim, Yong-Hyun,Babu, V. Ramesh,Thangadurai, Daniel T.,Rao, K.S.V. krishna,Cha, Hyeong-Rae,Kim, Chang-Dae,Joo, Woo-Hong,Lee, Yong-Ill Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.2
Copolymeric silver nanocomposite hydrogels were synthesized by using acryloyl phenylalanine (APA), N'-isopropylacrylamide (NIPAM) and crosslinked by N,N-methylene bisacrylamide (MBA) via radical redox polymerization. Present study allows entrapping silver nanoparticles into hydrogel networks. UV-visible spectroscopy and X-ray diffraction (XRD) studies confirmed the formation of silver nanoparticles in hydrogel matrix. 11% of weight loss difference between hydrogel and silver nanocomposite hydrogel is clearly indicates the formation and silver nanoparticles by thermo-gravimetrical analysis. The order of swelling capacity values of hydrogels and silver nanocmposite hydrogels were found to be in the order of placebo copolymeric hydrogel >Ag-copolymeric silver nanocomposite hydrogels. The particle size of silver nanoparticles was analysed and are in the range of 5 - 10 nm which has been confirmed by transmission electron microscopy (TEM) as well as particle size analysis. The silver nanocomposite hydrogel has shown very good antibacterial activity on gram-positive and gram-negative bacteriocides.
M. Amuthasurabi,J. Chandradass,V Ramesh Babu,P.Baskara Sethupathi,M. Leenus Jesu Martin 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.11
We report on the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by using radio frequency (rf) magnetron sputtering technique. The TFT device structure used in this study was a bottom gate type, which consists of SiNx as a gate insulator and indium tin oxide (ITO) as a gate deposited onto corning glass substrates. Electrical characteristics of the device showed clear saturation region without any output current degradation due to self heating effect. These ZnO TFTs had a saturation field effect mobility of about 2.14 cm2/Vs, an on to off ratio of greater than 105, the off current of less than 10−10 A and a threshold voltage of 15 V at a maximum device processing temperature of 350 oC. This TFT had a channel width of 300 μm and channel length of 30 μm. Moreover, the SiNx dielectric layer was found to be optimum for the high performance ZnO based TFTs because of the very low leakage current and good interface between the channel layer and gate material.
Nalina B. S.,Kamaraj V.,Babu M. Ramesh 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4
Faults in power electronic converters interfaced to renewable energy systems are caused due to malfunction of system components, short circuits in converters, commutation failures. These faults aff ect the performance of the system. Therefore, to improve the performance of the system, these faults have to be detected and identifi ed. In this paper, fault detection and identifi cation strategy are designed, analyzed both mathematically and experimentally based on the design of Luenberger observer. Two diff erent types of fi lters are incorporated in the system which includes Fault Detection (FD) fi lter and Fault Identifi cation (FI) fi lters. The design structures of both the fi lters are based on the design of Luenberger observer. Initially, the fault detection fi lters are activated to detect the availability of fault. Once the fault is identifi ed, a set of fault identifi cation fi lters are initialized to identify the type of fault. Each type of fault is determined by each fi lter in the set of fault identifi cation fi lters. In this paper inductor fault, capacitor fault and switch fault are analyzed. The proposed strategy is verifi ed on an Interleaved Bidirectional Switched Capacitor DC–DC converter interfaced to a solar powered Microgrid using theoretical and simulation results. Finally, a prototype is fabricated to validate the performance of the system.