Highly Sensitive Flexible Photodetectors Based on Self-Assembled Tin Monosulfide Nanoflakes with Graphene Electrodes

Mohan Kumar, Ganesan,Fu, Xiao,Ilanchezhiyan, Pugazhendi,Yuldashev, Shavkat U.,Lee, Dong Jin,Cho, Hak Dong,Kang, Tae Won American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.37

<P>Tin monosulfide (SnS) nanostructures have attracted huge attention recently because of their high absorption coefficient, high photoconversion efficiencies, low energy cost, ease of deposition, and so on. Here, in this paper, we report on the low-cost hydrothermal synthesis of the self-assembled SnS nanoflake-like structures in terms of performance for the photodetectors. High-performance photodetectors were fabricated using SnS nanoflakes as active layers and graphene as the lateral electrodes. The SnS photodetectors exhibited excellent photoresponse properties with a high responsivity of 1.7 X 10(4) A/W and have fast response and recovery times. In addition, the photodetectors exhibited long-term stability and strong dependence of photocurrent on light intensity. These excellent characteristics were attributed to the larger surface-to-volume ratio of the self-assembled SnS nanoflakes and the effective separation of the photogenerated carriers at graphene/SnS interfaces. Additionally, a flexible photodetector based on SnS nanoflakes was also fabricated on a flexible substrate that demonstrated similar photosensitive properties. Furthermore, this study also demonstrates the potential of hydrothermal-processed SnS nanoflakes for high-performance photodetectors and their application in flexible low-cost optoelectronic devices.</P>

Solution processed n-In2O3nanostructures for organic-inorganic hybrid p-n junctions

Kumar, G. Mohan,Kumar, A. Madhan,Ilanchezhiyan, P.,Kang, T. W. The Royal Society of Chemistry 2014 Nanoscale Vol.6 No.19

<P>Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 1020 cm-3 were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.</P>

Effect of Vowel Context on the Recognition of Initial Consonants in Kannada

Mohan Kumar Kalaiah,Jayashree S Bhat 대한청각학회 2017 Journal of Audiology & Otology Vol.21 No.3

Background and Objectives: The present study was carried out to investigate the effect ofvowel context on the recognition of Kannada consonants in quiet for young adults. Subjectsand Methods: A total of 17 young adults with normal hearing in both ears participatedin the study. The stimuli included consonant-vowel syllables, spoken by 12 native speakersof Kannada. Consonant recognition task was carried out as a closed-set (fourteen-alternativeforced-choice). Results: The present study showed an effect of vowel context on theperception of consonants. Maximum consonant recognition score was obtained in the /o/vowel context, followed by the /a/ and /u/ vowel contexts, and then the /e/ context. Poorestconsonant recognition score was obtained in the vowel context /i/. Conclusions: Vowel contexthas an effect on the recognition of Kannada consonants, and the vowel effect wasunique for Kannada consonants.

Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

Mohan Kumar, G.,Ilanchezhiyan, P.,Madhan Kumar, A.,Yuldashev, Sh.U.,Kang, T.W. Elsevier 2016 Chemical physics letters Vol.649 No.-

<P>A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current-voltage characteristics on the fabricated PPy/A1 doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications. (C) 2016 Elsevier B.V. All rights reserved.</P>

Relation between Phonological Processing,Auditory Processing and Speech Perceptionamong Bilingual Poor Readers

Mohan Kumar Kalaiah 대한청각학회 2015 Journal of Audiology & Otology Vol.19 No.3

Background and Objectives: A deficit in phonological processing abilities has been hypothesized as a cause of reading deficits among poor readers, but the precise etiology of this deficit is still unknown. Many studies have investigated the relation of auditory processing and speech perception with phonological processing, while the relation between these are not well understood. Thus, the present study was carried out to investigate the relation between these abilities among poor readers. Subjects and Methods: A total of 20 children between 7-12 years of age participated in the study. Among these 10 were typically developing children and 10 were poor readers. Auditory processing, speech perception in noise and phonological processing skills were assessed in both the groups. Results: Auditory processing was not significantly different between children in both the groups. In contrast, phonological awareness, verbal short-term memory and rapid automatized naming, which reflect phonological processing, and speech perception in noise were found to be significantly affected in poor readers. In addition, the results showed a significant correlation between phonological processing and speech perception in noise. Conclusions: The present study found a significant relationship between speech perception in noise and phonological processing, while there was no relationship between auditory processing and phonological processing. This finding suggests that poor speech perception among poor readers may be one of the contributing factors for phonological processing deficits, which in turn leads to reading difficulties.

Numerical analysis of pressure drop and temperature in a hairpin heat exchanger with different shell and tube bank arrangements

Mohan Kumar Dey,Nanjundan Parthasarathy,이연원 한국마린엔지니어링학회 2020 한국마린엔지니어링학회지 Vol.44 No.4

In this numerical study, the hairpin type shell and tube heat exchanger is analyzed for heating the cryogenic liquefied natu-ral gas (LNG). The cryogenic LNG is passed through the tube side and is heated by the hot water on the shell side of the hairpin heat exchanger. In order to increase the performance of the heat exchanger, maximum heat needs to be extracted from the hot water and transferred to the LNG stream. Thus, different arrangement of shell and tube sides of the hairpin heat exchanger are used to study the pressure drop in the hot water and to increase the temperature of the LNG. The effects of horizontal and vertical baffles orientation, staggered and aligned tube bank arrangements, baffles number (6, 8, 10 and 12), and baffles cut percentages were used to analyze the pressure drop and temperature difference in the exchanger. The results show that the pressure drop is decreased and the tube outlet temperature is increased in the heat exchanger for the percentage of baffle cut changes from 22.5% to 37.5%. Also, increasing the number of baffles increases both the temperature and pressure drop in the hairpin heat exchanger. Furthermore, comparing horizontal and vertical baffle orientation, pressure drop is always lower and LNG outlet temperature is always higher in the horizontal baffle orientation for both tube bank arrangement systems. However, in the horizontal baffle orientation the pressure drop for staggered tube bank arrangement is smaller than that of aligned tube bank arrangement, but the temperature of aligned tube bank is higher compared to the staggered tube bank arrangement.

Electrochemical studies on two-dimensional ZnInO nanoplates for organic–inorganic hybrid photodiode related applications

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T.W. Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.619 No.-

<P><B>Abstract</B></P> <P>An ultra low cost route has been established to fabricate organic–inorganic hybrid <I>p</I> <I>–</I> <I>n</I> junctions <I>via</I> chemical <I>in-situ</I> polymerization of organic monomers on traditionally drop casted inorganic deposits. In this regard, ZnInO nanoplate-like structures were synthesized through a facile solution based chemical approach and their structural property was studied using X-ray diffraction patterns. The nature of charge carriers and donor density in ZnInO made electrodes were studied using electrochemical impedance spectroscopy. The dissemination of polymer matrices on the ZnInO nanoplates was examined through scanning electron microscopy. The current–voltage characteristics obtained across the polypyrrole/ZnInO made hybrid structures revealed an improved rectifying behaviour under illuminated conditions. The mechanism behind the drastic decrease in resistance values that substantiates the improved electron transfer characteristics across the organic–inorganic structures was studied through cyclic voltammetric measurements.</P>

Cortical Auditory Event Related Potentials (P300) for Frequency Changing Dynamic Tones

Mohan Kumar Kalaiah,Usha Shastri 대한청각학회 2016 Journal of Audiology & Otology Vol.20 No.1

Background and Objectives: P300 has been studied with a variety of stimuli. However, the nature of P300 has not been investigated for deviant stimuli which change its characteristics from standard stimuli after a period of time from onset. Subjects and Methods: Nine young adults with normal hearing participated in the study. The P300 was elicited using an oddball paradigm, the probability of standard and deviant stimuli was 80% and 20% respectively. Six stimuli were used to elicit P300, it included two pure-tones (1,000 Hz and 2,000 Hz) and four tone-complexes (tones with frequency changes). Among these stimuli, 1,000 Hz tone served as standard while others served as deviant stimuli. The P300 was recorded in five separate blocks, with one of the deviant stimuli as target in each block. Electroencephalographic was recorded from electrode sites Fz, Cz, C3, C4, and Pz. Latency and amplitude of components of the cortical auditory evoked potentials were measured at Cz. Results: Waveforms obtained in the present study shows that, all the deviant stimuli elicited obligatory P1-N1-P2 for stimulus onset. 2,000 Hz deviant tone elicited P300 at a latency of 300 ms. While, tone-complexes elicited acoustic change complex (ACC) for frequency changes and finally elicited P300 at a latency of 600 ms. In addition, the results showed shorter latency and larger amplitude ACC and P300 for rising tone-complexes compared to falling tone-complexes. Conclusions: Tone-complexes elicited distinct waveforms compared to 2,000 Hz deviant tone. Rising tone-complexes which had an increase in frequency elicited shorter latency and larger amplitude responses, which could be attributed to perceptual bias for frequency changes.

Fabrication of polypyrrole/ZnO nanowires based organic–inorganic hybrid p-n junctions

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T. W. Springer Science + Business Media 2015 Journal of materials science Materials in electron Vol.26 No.4

Short Term Test-Retest Reliability of Contralateral Inhibition of Distortion Product Otoacoustic Emissions

Mohan Kumar Kalaiah,Alina Lasrado,Nikita Pinto,Usha Shastri 대한청각학회 2018 Journal of Audiology & Otology Vol.22 No.4

Background and Objectives: Strength of medial olivocochlear reflex can be measured reliably using contralateral inhibition of distortion product otoacoustic emissions (DPOAEs) when its fine structure is considered. However, measurement of fine structure of DPOAE is difficult with clinical equipment. Thus, this study investigated the clinically relevant test-retest reliability of contralateral inhibition of DPOAEs. Subjects and Methods: Twenty-six young adults withnormal hearing sensitivity participated. DPOAEs were recorded at 27 discrete f2 frequenciesbetween 800 Hz and 8,000 Hz at frequency resolution of 8 points per octave with and withoutcontralateral white noise presented at 50 dB SPL. To check for short term inter-sessionreliability, contralateral inhibition of DPOAEs were recorded in three sessions, two recordingsessions on first day separated by 30 minutes and third time after one week of the first session. Within each session, DPOAEs were recorded twice in single probe-fit condition to testfor intra-session reliability. Results: Cronbach’s alpha was calculated having poor reliability (α≤0.7) of contralateral inhibition of DPOAEs in both intra-session and inter-session conditionsfor most of the tested frequencies. 95% confidence intervals of contralateral inhibition magnitudealso showed large variability. Conclusions: The current results showed that thoughDPOAE amplitudes were highly reliable across sessions, amount of inhibition of DPOAEs wasnot reliable when DPOAEs were measured at discrete frequencies. These findings are concurrentwith the literature.