BHU

Vārānasi, India
Vārānasi, India

Time filter

Source Type

News Article | May 26, 2017
Site: www.nanotech-now.com

Abstract: In the recent past ZnO has emerged as a promising alternative to Si and GaN in devices like light-emitting diodes (LEDs), photodetectors, and optically pumped lasers for the UV region1-3. ZnO has several special properties such as direct wide bandgap (~3.37eV)4, radiation resistance, high adsorption capacity, high exciton energy (~60meV)4, high mechanical and thermal stabilities, and transparency in the visible range of the electromagnetic radiation4-6. In recent times, one-dimensional (1-D) nanostructures of ZnO have attracted considerable attention of researchers, because of its unique properties (such as controllable shape and size)7-10. A variety of 1-D nanostructures of ZnO, such as nanostructures7, nanowires (NWs)8, nanorods (NRs)9, nanoparticles10, spirals11, nanoneedle12, and nanocombs13 can be grown by different synthesis techniques7-13. Among these 1-D nanostructures, NRs and NWs are the most popular and commonly used structures of ZnO, for different applications. The ZnO-NRs can be grown by a variety of techniques like sol-gel method14, atomic layer deposition (ALD)15, thermal evaporation16, electrodeposition17, spray pyrolysis18, hydrothermal9, and chemical vapor deposition19. Most of these growth techniques are complex and require high growth temperatures (600-1000°C)12, 16. The hydrothermal method has attracted considerable interest because of its simplicity and low-temperature processing9, 20-23. Different nanostructures of ZnO such as nanoflowers21, nano-crystals22, and nanopencils23 could be grown by hydrothermal techniques. In the past decade, a lot of work has been done on ZnO-NR-based devices like optically pumped lasers24, field effect transistors25, and biological and chemical sensors etc26. Among these, ZnO-NR-based UV detectors and optical switches have been the focus of wide studies 27, 28. In recent times, many groups have reported the UV detection properties of ZnO thin films and ZnO nanostructures-based devices28-30. Li et al. reported Au/ZnO NR array-based UV photodetectors (UV-PDs) with good sensitivity (contrast ratio ~ 4.7)30. They have grown ZnO-NR arrays on F-doped SnO2 (FTO) substrates by hydrothermal synthesis. Humayun et al. reported a ZnO nanostructure decorated microgap electrodes UV sensor. They have compared the UV sensing properties of Au/Ti/ZnO thin film and Au/Ti/ZnO NR array deposited in selective areas of the microgap electrodes spacing31. They concluded that the fabricated devices could be used for low power miniaturized devices having rapid response and reproducibility31. Witkowski et al. have reported UV detector properties of ZnO-NRs grown on quartz substrates by the hydrothermal method. They have fabricated ohmic contacts of Ti/Au on ZnO-NRs and their detector showed a sensitivity of 20 mW/m2 upon UV illumination32. Zhou et al. reported Pt/ZnO-NR and Pt/modified ZnO-NR based Schottky UV detectors. They have used different seed layers and metal oxide (MgZnO, MgO, and Al-doped ZnO) modifying layer materials. They reported that the ZnO-NRs UV-PD, which was grown on MgZnO seed layer and without oxide material-coating, demonstrated bigger responsivity and a larger detectivity than PDs with a ZnO seed layer33. Liu et al. have reported UV detectors based on the vertically aligned ZnO micro/nanowires on graphene, which showed high responsivity of 1.62 A W?1 per volt34. Nie et al. have reported monolayer graphene (MLG) film/ZnO NR Schottky UV detectors with quick response of millisecond rise time/fall times35. Dang et al. have reported ZnO nanostructure/graphene (Gr) based UV detectors with high responsivity (RI ~ 3 × 105 A W?1)36. Although there have been several works that reported on the UV-sensing properties using ZnO NRs, there are only a few reports on the UV-sensing of ZnO-NRs (grown by the hydrothermal-method) at a low-voltage. The main focus of this work is to examine the UV-sensing characteristics of Ag/ZnO-NRs Schottky devices at forward applied bias over the range 0 V to 1 V. The results show that these devices could be useful for cost-effective and low-voltage UV detection applications. ### Additional co-authors of this paper include Dr. Shaivalini Singh, International Research Professor, Department of Electronic Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do South Korea and Professor S. Jit, Associate Professor, Department of Electronics Engineering, Indian Institute of Technology, BHU, Varanasi, India. The corresponding author is Professor Si-Hyun Park, Department of Electronic Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do South Korea, . For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | May 25, 2017
Site: www.eurekalert.org

In the recent past ZnO has emerged as a promising alternative to Si and GaN in devices like light-emitting diodes (LEDs), photodetectors, and optically pumped lasers for the UV region1-3. ZnO has several special properties such as direct wide bandgap (~3.37eV)4, radiation resistance, high adsorption capacity, high exciton energy (~60meV)4, high mechanical and thermal stabilities, and transparency in the visible range of the electromagnetic radiation4-6. In recent times, one-dimensional (1-D) nanostructures of ZnO have attracted considerable attention of researchers, because of its unique properties (such as controllable shape and size)7-10. A variety of 1-D nanostructures of ZnO, such as nanostructures7, nanowires (NWs)8, nanorods (NRs)9, nanoparticles10, spirals11, nanoneedle12, and nanocombs13 can be grown by different synthesis techniques7-13. Among these 1-D nanostructures, NRs and NWs are the most popular and commonly used structures of ZnO, for different applications. The ZnO-NRs can be grown by a variety of techniques like sol-gel method14, atomic layer deposition (ALD)15, thermal evaporation16, electrodeposition17, spray pyrolysis18, hydrothermal9, and chemical vapor deposition19. Most of these growth techniques are complex and require high growth temperatures (600-1000°C)12, 16. The hydrothermal method has attracted considerable interest because of its simplicity and low-temperature processing9, 20-23. Different nanostructures of ZnO such as nanoflowers21, nano-crystals22, and nanopencils23 could be grown by hydrothermal techniques. In the past decade, a lot of work has been done on ZnO-NR-based devices like optically pumped lasers24, field effect transistors25, and biological and chemical sensors etc26. Among these, ZnO-NR-based UV detectors and optical switches have been the focus of wide studies 27, 28. In recent times, many groups have reported the UV detection properties of ZnO thin films and ZnO nanostructures-based devices28-30. Li et al. reported Au/ZnO NR array-based UV photodetectors (UV-PDs) with good sensitivity (contrast ratio ~ 4.7)30. They have grown ZnO-NR arrays on F-doped SnO2 (FTO) substrates by hydrothermal synthesis. Humayun et al. reported a ZnO nanostructure decorated microgap electrodes UV sensor. They have compared the UV sensing properties of Au/Ti/ZnO thin film and Au/Ti/ZnO NR array deposited in selective areas of the microgap electrodes spacing31. They concluded that the fabricated devices could be used for low power miniaturized devices having rapid response and reproducibility31. Witkowski et al. have reported UV detector properties of ZnO-NRs grown on quartz substrates by the hydrothermal method. They have fabricated ohmic contacts of Ti/Au on ZnO-NRs and their detector showed a sensitivity of 20 mW/m2 upon UV illumination32. Zhou et al. reported Pt/ZnO-NR and Pt/modified ZnO-NR based Schottky UV detectors. They have used different seed layers and metal oxide (MgZnO, MgO, and Al-doped ZnO) modifying layer materials. They reported that the ZnO-NRs UV-PD, which was grown on MgZnO seed layer and without oxide material-coating, demonstrated bigger responsivity and a larger detectivity than PDs with a ZnO seed layer33. Liu et al. have reported UV detectors based on the vertically aligned ZnO micro/nanowires on graphene, which showed high responsivity of 1.62 A W?1 per volt34. Nie et al. have reported monolayer graphene (MLG) film/ZnO NR Schottky UV detectors with quick response of millisecond rise time/fall times35. Dang et al. have reported ZnO nanostructure/graphene (Gr) based UV detectors with high responsivity (RI ~ 3 × 105 A W?1)36. Although there have been several works that reported on the UV-sensing properties using ZnO NRs, there are only a few reports on the UV-sensing of ZnO-NRs (grown by the hydrothermal-method) at a low-voltage. The main focus of this work is to examine the UV-sensing characteristics of Ag/ZnO-NRs Schottky devices at forward applied bias over the range 0 V to 1 V. The results show that these devices could be useful for cost-effective and low-voltage UV detection applications. Additional co-authors of this paper include Dr. Shaivalini Singh, International Research Professor, Department of Electronic Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do South Korea and Professor S. Jit, Associate Professor, Department of Electronics Engineering, Indian Institute of Technology, BHU, Varanasi, India. The corresponding author is Professor Si-Hyun Park, Department of Electronic Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do South Korea, sihyun_park@ynu.ac.kr. This research (DOI) can be found in the NANO journal.


Gravity and magnetic studies have been carried out to map the different depth formations of alluvium, Gondwana, Vindhyan, Mahakoshal, and the crystalline basement in the Narmada-Son lineament (NSL) near the Sahdol-Katni area, India. Higher elevations in the northern part of the study area have lower gravity; the southern part of the study area, however, is moderately elevated and also has a higher gravity anomaly, which justifies the isostatic adjustment. This indicates the presence of high-density material, for example Mahakoshal rocks, in the upper crust which causes the higher anomaly value. The Mahakoshal rocks are widely exposed at Mau, Chanaura, Nadawar, Khamaria, Umria, and near the Tala-Barhi area and also extend from Sidhi to Agoni village further east of the area. The Mahakoshal rocks are thinner between the river Son and Tikwa village which causes a different gravity anomaly pattern changing from the NNE-SSW direction to the N-S direction. However, the trend of magnetic anomaly follows the same pattern toward the NNE-SSW direction, mainly because of the effect of the crystalline basement. Two magnetic highs are prominent in the Tikwa and Amarpur regions, 800 and 400 nTesla, respectively, because of the presence of the crystalline basement. The depth of the crystalline basement obtained by 21/2 D gravity-magnetic modeling varies from 2.7 to 2.9 km. From spectral analysis the average depth of the crystalline basement varies from 2.83 to 3.05 km. The different crustal depth sections obtained by 21/2 D simultaneous gravity-magnetic modelling correlate well with other constrained data. © 2010 Springer Basel AG.


Agarwal M.,BHU | Sharma A.,Banasthali Vidyapeeth
Journal of Health Management | Year: 2011

The study was conducted with the aim of investigating the effects of perception of the hospital workplace factors on the job satisfaction and psychological well-being of a sample of paramedical health care employees (N = 200) from a medical college (teaching) hospital and public (non-teaching) government-run hospitals. Statistical analysis of the data revealed that despite significant differences in perceived work-place factors, the reported levels of psychological well-being and job satisfaction of the participants were nearly similar in the two types of public hospitals. Stepwise regression analysis of the data revealed that the organization's structure-related factors, co-ordination and work autonomy were significantly predictive of job satisfaction and psychological well-being of health care employees, while the process-related workplace factors, participative decision making and intra-professional relations, emerged as significant predictors of psychological well-being and job satisfaction in both types of hospitals. Results have significant implications for public hospitals which are currently facing competition from the state-of-the-art health care technology being introduced by private hospitals, and are therefore under pressure for retention of skilled health care employees. © 2011 SAGE Publications.


Dental implants treatment have become a common modality of treatment nowadays for the replacement of missing tooth/teeth, but there have been failures due to a number of reasons; one of the rare problems is the fracture of the dental implants fixture. It is of prime importance to understand the type/system of the implant to be placed in a site and the amount and direction of occlusal forces incurred after the loading of prosthesis.


Mandai R.K.,Indian Institute of Technology BHU Varanasi | Tiwari R.S.,BHU | Singh D.,Panjab University | Singh D.,BHU
Materials Research Society Symposium Proceedings | Year: 2015

In this presentation, results of our recent investigations on the role of Ga on Al site in Zr69.5Al75.xGaxCu12Ni11 and Ce75Al25-xGax metallic glass compositions will be discussed. Ga like Al is normally expected to be in trivalent state. However, it may go in monovalent state depending on other alloying elements. The rapidly solidified melt spun ribbons of above two alloys gave rise to two important conclusions. The Zr69.5Al75-xGaxCu12Ni11 system displayed metallic glass formation in the range of x=0 to 7.5. In this process, we have come out with a new composition of glass without Al corresponding to x=7.5. In contrast to the above, for Ce-Al(Ga) system, we have observed phase separation in glass after dilute substitution of Ga. It seems that such a phase separation in this system cannot be understood in terms of summation of enthalpy of mixing of the various possible binaries in this system. The substitution of Ga in different valence states might have created chemical pressure leading to creation of two types of distinct major clusters. The phase separation may be due to this. This has also given rise to excursion of Ce 4f-states of the alloy. This and aforesaid 'chemical pressure' will be corroborated based on results of binary Ce-Al system under pressure by other investigators. © 2015 Materials Research Society.


Singh S.,BHU | Vishwakarma D.N.,BHU
International Conference on Microelectronics, Computing and Communication, MicroCom 2016 | Year: 2016

This paper presents a novel approach based on combined wavelet transform and artificial intelligence technique for estimating fault location in a series compensated transmission line. In proposed approach the samples of faulty current signals generated from simulink model are used for fault analysis. Wavelet transform is utilised for the purpose of feature extraction from the faulty current signals. The fault current signals are decomposed using Db5 mother wavelet. Features of faulty signals are extracted in terms of standard deviation and norm entropy value of the coefficients and are fed to designed artificial neural network (ANN) models for fault distance estimation. The paper also presents a comparison of error in estimating the distance of fault by different neural network i.e. Feed-forward, Cascade-forward and generalized regression neural network (GRNN). The preciseness and workability of the proposed algorithm has been evaluated on a 400 KV, 300 km series compensated transmission line for different fault cases using MATLAB simulation. The results acquired, indicate that the proposed approach can reliably located the faults points in series compensated transmission line with high accuracy. © 2016 IEEE.


Singh M.P.,Allahabad University | Pandey A.K.,Purvanchal University | Vishwakarma S.K.,Purvanchal University | Srivastava A.K.,Purvanchal University | And 2 more authors.
Cellular and Molecular Biology | Year: 2014

In the present investigation three species of Pleurotus i.e. P. sajor-caju (P1), P. florida (P2) and P. flabellatus (P3) along with two lignocellulosic substrates namely paddy straw and wheat straw were selected for evaluation of production of extracellular cellulolytic enzymes. During the cultivation of three species of Pleurotus under in vivo condition, the two lignocellulosic substrates were treated with plants extracts (aqueous extracts of ashoka leaves (A) and neem oil (B)), hot water (H) and chemicals (C).Among all treatments, neem oil treated substrates supported better enzyme production followed by aqueous extract of ashoka leaves, hot water and chemical treatment. Between the two substrates paddy straw supported better enzyme production than wheat straw. P. flabellatus showed maximum activity of exoglucanase, endoglucanase and β-glucosidase followed by P. florida and P. sajor-caju. © 2014.


Naik A.S.,BHU
Proceedings of the 16th International Association for Mathematical Geosciences - Geostatistical and Geospatial Approaches for the Characterization of Natural Resources in the Environment: Challenges, Processes and Strategies, IAMG 2014 | Year: 2014

Coal has been the leading fuel in the energy industry.Its usage has shown far reaching consequences to health and environment.Occurrence of PAH in coal is well known fact but its effect to the human health is least addressed.It is one of the dangerous carcinogens with its ubiquitous presence in the environment.The present investigation on few coal samples reveals presence of substantial amount of PAH in the Mahanadi basin coalfields.Proper mitigation of this substance is required to ensure proper health of the miners and personnel in coal industry.Among the PAH reported are Anthracene, Benzo(a)pyrene, Phenanthrene and Pyrene etc.According to International Agency for Research on Cancer (IARC) a study in 1936 by investigators in Japan and England showed lung cancer mortality among workers in coal carbonization and gasification processes.Later on studies in US was carried on coke oven workers which confirmed the lung cancer mortality, with the suggestion of excessive genitourinary system cancer mortality.Given these implications this investigation attempts to address PAH in the coals of Mahanadi basin. © 2014, Capital Publishing Company.


Since the Precambrian time the Narmada-Son Lineament (NSL) is a zone of weakness and both the northern and southern portions of Narmada-Son Lineament experienced vertical block movements. It is established by the earlier workers that NSL is a sub-crustal feature which is responsible for the deposition and folding of the Vindhyans (Meso- Neoproterozoic) and Gondwanas (Permo-Carboniferous-lower Cretaceous). Recent tectonic activity in the Narmada- Son region is evidenced by high heat flow thermal activity, sulphur springs and seismically the Narmada-Son Lineament region is known to be a significantly disturbed zone. The present study area is the part of Narmada-Son Lineament zone. The drainage geomorphology of the area between Kanahar and Rihand rivers (tributaries of the tectonically controlled Son river) around Renukoot area have been studied aiming to understand active tectonics of the region, integrating detailed analysis of landforms and drainages. Various geomorphic features present in the study area such as incision of valley, aligned drainage, aligned valleys, linear valleys, offset channels, offset ridges and fault scarps demonstrate that the area is undergoing active deformation. © 2014, Geological Society of India.

Loading BHU collaborators
Loading BHU collaborators