Growth and Characterization of Pulse Electrodeposited CuInSe2 Thin Films

Dixit Prasher,Poolla Rajaram 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.5

CuInSe2 thin films were grown on SnO2-coated glass substrates using the pulse electrodeposition (PED) technique. The CuInSe2 films were grown at different potentials using pulses of different frequencies ranging from 1 KHz to 1 MHz. The electrodeposited films were annealed in vacuum at 300°C, for 1 hr, to improve the crystallinity. The annealed films were characterized by x-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of x-rays (EDAX), and UV-VIS-NIR spectra. The results show that the electrodeposited CuInSe2 films have good stoichiometry and are single phase with an optical gap around 1 eV. SEM studies show that the films grown using pulses of frequency 1 KHz contain nanoparticles of size 50-60 nm, whereas those grown using pulses of frequency 100 KHz and 1 MHz contain micronsized particles.

불포화 사질토양을 이용한 도시하수의 3차 처리

김승현,정종배,하현수,Prasher, Shiv O. 한국환경농학회 2003 한국환경농학회지 Vol.22 No.2

모래층 토양이 도시하수의 l3차 처리에 이용될 경우 COD 제거율은 적용유량에 관계없이 약 70%에 이르는 것을 알 수 있었다. 적용유량이 증가함에 따라 COD제거에 필요한 토양층의 깊이가 증가하여 50 L/day의 유량에서는 약 60 cm에 달하는 것을 알 수 있었다. 질산화는 매우 빨라서 표층토양 10~20 cm에서 반응이 거의 완료됨을 알 수 있었다. 총질소의 제거율은 유량에 상관없이 약 20%로 낮은 편이었으며, 이에 대한 보완책이나 추가적인 연구가 필요한 것으로 판단된다. 잔디를 식재할 경우 오염물의 처리효율에는 영향이 거의 없으나 투수능 유지에는 도움이 되는 것을 알 수 있었으며, 토양에 함유된 유기물로부터 상당한 양의 오염물이 용출되는 것을 알 수 있었다. 탈질과정에서는 아산화질소도 발생하므로 본 연구의 결과를 현장에 적용하기 전에 이에 대한 추가적인 연구도 필요할 것으로 판단된다. Treatment of secondary effluent was investigated using sandy soil as a possible alternative to the tertiary treatment of municipal wastewater. Secondary effluent was applied with three different flow rates to the surface of pilot scaled lysimeters, which were filled with sandy soil. Some of the lysimeters were covered with sod, while others were kept bare in order to investigate the role of plantation on the treatment. The concentration changes in COD and nitrogen were measured along the unsaturated soil depth. The same set of experiment as with the secondary effluent was performed using tap water to investigate the dissolution of the contaminants from the soil. From the results it was found that when sandy soil was used for tertiary treatment of municipal wastewater COD removal efficiency reached about 70% regardless of the application rate. The soil depth needed to obtain such efficiency increased along with the application rate, which was about 60 cm at the application rate of 50 Wday. Results also showed that nitrification occurred rapidly. The process was completed in soil depth of first 10-20 cm Nitrogen removal efficiency was as low as about 20% regardless of the application rate. Some supplementary means should be considered to improve the efficiency. Sod on the soil surface had no significant influence on the contaminant treatment but was helpful to keep the infiltration rate undiminished. Finally, the organic soil was found to release significant amount of contaminants when it was in contact with soil water.

Factors affecting the electrical conductivity of conducting polymers

Pooja,Kumar Anil,Prasher Parteek,Mudila Harish 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Metals had been significantly substituted by synthetic polymers in most of our daily requirements, thus relaxing our life. Out of many applied areas, synthetic polymers especially conducting polymers had shown their marked effect and potential. Batteries, pseudocapacitors, superconductors, etc. are the potential zones where conducting polymers are chiefly employed owing to their appreciable conductivity, cost efficiency, and corrosion inhibition nature. Apart from energy storage devices, these conducting polymers find their potential application in biosensors, lasers, corrosion inhibitors, electrostatic materials, conducting adhesives, electromagnetic interference shielding, and others. These all applications including energy storage are due to astonishing properties like high conductivity, flexibility, tuneability, easy processibility, chemical, thermal and mechanical stability, easy and enhanced charge transportation, lightweight, etc. Conducting polymers are extensively studied for their application in energy storage batteries, for which the material under investigation needs to be electrically conductive. However, the conducting nature of these specific conducting polymers is dependent on numerous factors. This review discussed the effect of certain potential factors such as polymerization techniques temperature, doping, bandgap, extended conjugation, solvent, etc. on the electrical/electrochemical conductivity of these conducting polymers. These all factors with their specific variations are found to have a noticeable consequence on the electrical conductivity of the investigated conducting polymer and hence on the energy storage carried by them. This review could be proved beneficial to the readers, who can judiciously implement the conclusions to their research related to conducting polymers and their composites for generating highly efficient energy storage systems.

Electrochemical oxidation-reduction and determination of urea at enzyme free PPY-GO electrode

Harish Mudila,Parteek Prasher,Sweta Rana,Beena Khati,M.G.H. Zaidi 한국탄소학회 2018 Carbon Letters Vol.26 No.-

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to 3.0 μM with a relatively low limit of detection of 0.27 μM. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

Phytochemical analysis and antimicrobial potential of Nigrospora sphaerica (Berk. & Broome) Petch, a fungal endophyte isolated from Dillenia indica L.

Vijay Kumar,I. B. Prasher 경희대학교 융합한의과학연구소 2023 Oriental Pharmacy and Experimental Medicine Vol.23 No.2

Endophytic fungi from medicinal plants are a rich source of new biologically active compounds. In the present study, an endophytic fungus Nigrospora sphaerica (Berk. & Broome) Petch was isolated from Dillenia indica L and was characterized morphologically and at molecular levels. The isolated fungus was investigated for antibacterial activity, antifungal activity, antioxidant activity, total phenolics and flavonoids content, and its responsible bioactive molecules. The toxicity test revealed that the crude extract of Nigrospora sphaerica inhibited the growth of pathogenic bacteria, i.e., E. coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. The value of MIC (Minimum inhibitory concentration) ranges from 82–115 µg/mL for the selected bacteria. The isolated endophytic fungus exhibited the highest inhibition against the Fusarium oxysporum (72%) and the lowest inhibition against Aspergillus niger (55%). The maximum scavenging activity was 88.1% at 600 µg/mL with an IC50 value of 85 µg/mL. GC–MS (Gas chromatography-Mass spectroscopy) analysis of the ethyl acetate extract revealed the presence of more than 40 compounds. Some of the major compounds present in extract were 1H-Indene, 1-methylene-(3.64%), Dodecane (8.52%), Tetradecane (11.59%), (-)-Mellein (3.85%), Hexadecane (10.13%), 1,2,5-Oxadiazole-3,4-dicarboxamide (5.95%), Octadecane (6.46%) and Benzoic acid, 2-(dimethylamino) ethyl ester. The compounds present in the extracts have various biological activities such as antiviral, antioxidant, insecticidal, cytotoxic, antihyperglycemic, antibacterial, antifungal activity. The compounds present in the extract can be used in clinical trials for further applications. To the best of our knowledge, this is the first report on bioactive molecules produced by Nigrospora sphaerica isolated from Dillenia indica L. having antioxidant and antimicrobial activity.

Growth and Characterization of MgxZn1-xO Thin Films by Aerosol-Assisted Chemical Vapor Deposition (AACVD)

Akash Shukla,Vipin K. Kaushik,Dixit Prasher 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

The growth and characterization of MgxZn1-xO thin films by aerosol-assisted chemical vapor deposition (AACVD) technique is reported in this paper. We have grown the thin films of ZnO by adding varying concentrations of magnesium (Mg) on a glass substrate. The precursor from which the MgxZn1-xO thin films were grown was made up of a mixture of zinc acethylacetonate and magnesium acetate tetrahydrate in boiled isopropyl alcohol. Oxygen gas was used as a carrier gas and substrate temperature was maintained at 400°C. MgxZn1-xO thin films were finally characterized by x-ray diffraction (XRD), atomic force microscopy (AFM) and UV-VIS-NIR spectroscopy. XRD results show that MgxZn1-xO thin films displayed a wurtzite structure and addition of Mg leads to a slight shift towards higher 2-theta values. AFM results show that MgZnO thin films were uniformly covered with nano flakes and their size decreases with an increase in Mg content. Optical studies show that with the increase of Mg content, transparency as well energy band gap of the MgxZn1-xO thin films increases, which also agrees with the reported values.