Showing papers by "Mahesh Kumar published in 2014"

Defect-free ZnO nanorods for low temperature hydrogen sensor applications

Abstract: Uniformly distributed and defect-free vertically aligned ZnO nanorods (NRs) with high aspect ratio are deposited on Si by sputtering technique. X-ray diffraction along with transmission electron microscopy studies confirmed the single crystalline wurtzite structure of ZnO. Absence of wide band emission in photoluminescence spectra showed defect-free growth of ZnO NRs which was further conformed by diamagnetic behavior of the NRs. H2 sensing mechanism based on the change in physical dimension of channel is proposed to explain the fast response (∼21.6 s) and recovery times (∼27 s) of ZnO NRs/Si/ZnO NRs sensors. Proposed H2 sensor operates at low temperature (∼70 °C) unlike the existing high temperature (>150 °C) sensors.

Study of inter-relationship of depression, seizure frequency and quality of life of people with epilepsy in India

Abstract: Epilepsy is a chronic neurological disorder that can have profound physical, social and psychological consequences. We aimed to assess the clinical predictors of quality of life of people with epilepsy. We recruited 31 patients suffering from epilepsy in this cross-sectional study. Their clinical profile was recorded. Quality Of Life in Epilepsy (QOLIE-31) was used to assess quality of life of our patients. Depression was screened by Neurological Disorders Depression Inventory in Epilepsy (NDDI-E). Among all the clinical variables, only seizure frequency significantly correlated with seizure worry (P=0.002), emotional well-being (P=0.026) and social functions (P=0.013) subscales of QOLIE-31. NDDIE score showed a significant negative correlation with all the subscales of QOLIE-31 except medication effects (P=0.993). A significant positive correlation was also noted between seizure frequency and NDDI-E score (r=0.417, P=0.020). Seizure frequency and depression are the most important predictors of quality of life in epilepsy patients. The management of patients with epilepsy should not only be aimed at just preventing seizures but the treating clinicians should also be cognizant about depression which itself can significantly affect the quality of life of patients.

Temperature dependent electrical transport studies of self-aligned ZnO nanorods/Si heterostructures deposited by sputtering

Abstract: Self-aligned ZnO nanorods (NRs) were grown on n-Si(100) substrate by RF sputtering techniques. The NRs are uniformly grown on 2-inch wafer along [0001] direction. Single-crystalline wurtzite structure of ZnO NRs was confirmed by X-ray diffraction. The average diameter, height, and density of NRs are found 48 nm, 750 nm, and 1.26 × 1010 cm−2, respectively. The current-voltages (I-V) characteristics of ZnO NRs/Si heterojunction (HJ) were studied in the temperature range of 120–300 K and it shows a rectifying behavior. Barrier height (ϕB) and ideality factor (η) were estimated from thermionic emission model and found to be highly temperature dependent in nature. Richardson constant (A*) was evaluated using Richardson plot of ln(Io/T2) versus q/kT plot by linear fitting in two temperature range 120–180 K and 210–300 K. Large deviation in Richardson constant from its theoretical value of n-Si indicates the presence of barrier inhomogeneities at HJ. Double Gaussian distribution of barrier height with thermionic...

Onset of acute and transient psychotic disorder in India: a study of socio-demographics and factors affecting its outcomes.

Abstract: Introduction Before the advent of the ICD-10, (1) acute psychosis as a group did not exist separately and was classified under the broad category of schizophrenia. In India, Wig and Singh (2) made the first observation regarding the existence of acute psychosis as a separate nosological entity. Their work pointed towards an acute-onset psychosis having florid symptomatology and good prognosis and also highlighted that the equivalent nosological entities in ICD were acute psychosis of uncertain origin and hysterical psychosis. Another study from India (3) considered the existence of 2 types of acute psychosis, namely, acute psychosis with and without stress. Singh and Sachdeva (4) suggested that "acute schizophrenia episode" was different from schizophrenia and manic depressive psychosis (MDP) and stressed that it should not be included under schizophrenia. One study (5) described reactive psychosis which had manifested psychopathology, personality traits, life events, and family history. The landmark Indian Council of Medical Research (ICMR) acute psychosis study (6) found that 35% of cases were categorised as schizophrenia, 25% as MDP, and 40% as non-organic psychosis as per ICD-9. Moreover, 52% of the cases of acute psychosis could not be classified into any of the diagnostic categories. (6) Acute and transient psychotic disorder (ATPD) as a descriptive entity was recognised for the first time in 1992 when ICD-10 included it under psychotic disorder (F23) as a three-digit code. (1) Acute and transient psychotic disorder has certain key features, such as acute onset (within 2 weeks) and rapidly changing, variable polymorphic picture, which are accepted as defining criteria; stress may or may not be present with the condition. Recovery is complete within 2 to 3 months in most cases. (1) Epidemiological data on the incidence of acute psychosis suggest that acute and transient psychosis is 10 times more common in developing countries than in developed countries. (7) Despite the long period since ATPD received a distinct nosological status, its status as a separate diagnostic entity has been questioned time and time again because of its diagnostic instability due to overlap of symptoms with schizophrenia and affective psychosis in many cases. Relatively few studies from India have examined the diagnostic validators of ATPD and conclusive data are lacking. In view of the need to define this category more precisely, the current study aimed to delineate socio-demographics (an antecedent diagnostic validator as per schema of Robin and Guze (8)) and clinical variables associated with the onset of ATPD, and how these affect the outcome (a predictive diagnostic validator) of the same. Methods A retrospective study was conducted in the Department of Psychiatry, SMS Medical College and Hospital, Jaipur, India. Case notes of all inpatients diagnosed with ATPD (according to the ICD-10 diagnostic criteria) from 1 January 2012 to 31 December 2012 were analysed. A total of 191 such subjects were identified. Of these, patients who were discharged against medical advice (n = 2) or absconded (n = 4) were excluded as clinical improvement could not be established in these patients. The socio-demographic data of the patients were collected on a self-designed performa. Information regarding presence of a stressor prior to the onset of illness, family history of any psychiatric illness, history of substance abuse, duration of untreated illness (DUI), month of onset of psychosis, and duration of hospital stay was recorded. Stressors were categorised into biological (i.e. causing hormonal and biochemical changes) and psychosocial (i.e. changes in social environment). For the purpose of analysis, duration of hospital stay was used as a proxy for clinical outcome and treatment response. The response was arbitrarily divided into 2 groups: early response (duration of stay

Effects of growth temperature on nonpolar a-plane InN grown by molecular beam epitaxy

Abstract: Nonpolar a-plane InN films were grown on r-plane sapphire substrate by plasma assisted molecular beam epitaxy with GaN underlayer Effect of growth temperature on structural, morphological, and optical properties has been studied The growth of nonpolar a-plane (1 1 -2 0) orientation was confirmed by high resolution X-ray diffraction study The film grown at 500 °C shows better crystallinity with the rocking curve FWHM 067° and 085° along [0 0 0 1] and [1 -1 0 0] directions, respectively Scanning electron micrograph shows formation of Indium droplets at higher growth temperature Room tem-perature absorption spectra show growth temperature dependent band gap variation from 074–081 eV, consistent with the expected Burstein–Moss effect The rectifying behaviour of the I–V curve indicates the existence of Schottky barrier at the InN and GaN interface (© 2014 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim)

Investigation of chemically synthesized graphene as counter electrode for dye sensitized solar cells

Abstract: Graphene was synthesized and used as a counter electrode in place of platinum in dye sensitized solar cells. This study reveals that the graphene synthesized by reduction of graphene oxide still contains functional groups even after reduction. The synthesized graphene counter electrodes were prepared by screen printing fabrication techniques. The influence of temperature variation on the films morphology, crystallinity, and its interfacial adhesiveness to the fluorine doped tin oxide coated glass were studied. Screen printing technique has shown uniform surface, decreased agglomeration of nanoparticles and high film adhesiveness. The screen printed film annealed at 400°C reveals best surface morphology.

Studies on path coefficient analysis in papaya (Carica papaya L.)

Abstract: The present investigation was carried out at the Horticultural Research Centre of the Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut (U.P.) during 2010 and 2011. In Randomized Block Design with three replication using seventeen genotypes of papaya and fifteen various traits were recorded on randomly selected plants. Path coefficient analysis showed that fruit weight, Fruit per plant, plant height at flowering, days to flowering, fruit girth were the most important characters controlling directly effects on fruit yield per plant. Whereas, Path coefficient analysis showed that plant height, flower initiation, Days to flowering, plant height at flowering, petiole length, plant girth, number of leaves at flowering, fruit length, fruit girth, central cavity, pulp thickness, TSS, number of fruit per plant, fruit weight were most important characters indirectly effects on fruit yield per plant. The plants of genotype PS 1 yielded more fruits of superior quality. Yield and quality are the most important economic traits in papaya and therefore, this genotype can be recommended for selection.

Carbon coated stainless steel as counter electrode for dye sensitized solar cells

Abstract: A new type of counter electrode for dye sensitized solar cells has been fabricated using a stainless steel sheet as substrate and graphite, graphene and multiwall carbon nanotubes as the catalytic material which applied by screen printing technique. The sheet resistances of the substrates and there influence on the dye sensitized solar cells has been studied. The fabricated counter electrodes i.e. SS-graphite, SS-graphene SS-MWCNT and SS-platinum were tested for their photovoltaic response in the form of dye sensitized solar cells.

Study of InN nanorods growth mechanism using ultrathin Au layer by plasma-assisted MBE on Si(111)

Abstract: InN nanorods (NRs) were grown on Si(111) substrate by plasma-assisted molecular beam epitaxy. The growth of InN NRs has been demonstrated using an electron-beam evaporated (~2 nm) Au layer prior to the initiation of growth. The structure and morphology of as deposited Au film, annealed at 600 °C, and InN NRs were investigated using X-ray photoelectron spectroscopy and scanning electron microscopy. Chemical characterization was performed with energy dispersive X-ray analysis. Single-crystalline wurtzite structure of InN NRs is verified by transmission electron microscopy. The formation process of NRs is investigated and a qualitative mechanism is proposed.