Characteristics of black carbon over Delhi and Manora Peak - a comparative study

The characteristics of aerosol black carbon (BC) were studied at two different climatic regimes, i.e. Delhi and Manora Peak during winter and spring of 2007. Spring BC was found to be similar to 59% lower at Delhi and similar to 23% higher at Manora Peak than their corresponding winter BC. Diurnal BC variation showed two enhanced peaks at Delhi (morning and night) whereas a single late afternoon peak at Manora Peak. Delhi BC showed a clear correlation with prevailing winds whereas no correlation was observed at Manora Peak. The major contribution of BC at Manora Peak can be expected from biomass burning while at Delhi fossil fuel dominates

Small-signal Amplifier with Three Dissimilar Active Devices in Triple Darlington Topology

Abstract: A new circuit model of a small-signal amplifier is proposed and analyzed on the qualitative scale. Apart from routine biasing components, the proposed amplifier circuit uses two additional biasing resistances and three dissimilar active devices namely MOSFET, JFET and BJT in Triple Darlington configuration. Having a considerably low amount of distortion (0.71%), the proposed circuit successfully amplifies small-signals of 1-5mV range (at 1 KHz frequency) and simultaneously provides high voltage gain (189.846) and high current gain (16.542K) with moderate range bandwidth (369.529KHz). These properties offer a flexible application range to the proposed circuit as high voltage gain or high current gain or high power gain amplifier in permissible audio-frequency range. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters, bandwidth and total harmonic distortion of the amplifier are perused to provide a wide spectrum to the qualitative studies. Qualitative performance of the proposed amplifier is also compared with two different circuits which are respectively having BJT-JFET and BJT-MOSFET in Darlington pair configuration. The proposed amplifier may be useful for those applications where high voltage and current gain would be the prime requirement of amplification in audio frequency region

Minuscule weight percent of graphene oxide and reduced graphene oxide modified Ag3PO4: new insight into improved photocatalytic activity

Designing and fabricating hybrid systems with a visible light active semiconductor as one of its components is an important research area for the development of highly efficient photocatalysts. Herein, we report visible-light driven photocatalytic activity of graphene oxide (GO) and controllably reduced GO (rGO) modified Ag3PO4 composites fabricated by an in situ method. Concentration of graphene derivatives in GO/rGO-Ag3PO4 composites was in the range of 0.13-0.52 wt% which is very minute compared to those reported previously. The optimal concentration of GO in Ag3PO4 with a kinetics (k = 1.23 +/- 0.04 min(-1)) for the degradation of rhodamine B is 0.26 wt%. GO-Ag3PO4 photocatalysts display an improved catalytic activity compared with pristine and rGOs modified Ag3PO4. In line with this, GO/rGO-Ag3PO4 composites show improved photocatalytic activity for the degradation of 2-chlorophenol compared with Degussa P-25. Our experiments with GO reduced to different extents show that, rGO with more polar functional groups exhibits a higher photocatalytic efficiency. The photocatalytic activity in the presence of different scavengers reveals that holes and O-2(-center dot) reactive species play major roles in the degradation phenomenon. In view of our experimental results and reported theoretical studies, a change in conduction band energy level and variation in the contribution of different charge orbitals (C 2p and O 2p) to the conduction band in the composite favours electron flow from graphene derivatives to the semiconductor, enhancing its photocatalytic response

Most probable mixing state of aerosols in Delhi NCR, northern India

Unknown mixing state is one of the major sources of uncertainty in estimating aerosol direct radiative forcing (DRF). Aerosol DRF in India is usually reported for external mixing and any deviation from this would lead to high bias and error. Limited information on aerosol composition hinders in resolving this issue in India. Here we use two years of aerosol chemical composition data measured at megacity Delhi to examine the most probable aerosol mixing state by comparing the simulated clear-sky downward surface flux with the measured flux. We consider external, internal, and four combinations of core-shell (black carbon, BC over dust; water-soluble, WS over dust; WS over water-insoluble, WINS and BC over WINS) mixing. Our analysis reveals that choice of external mixing (usually considered in satellite retrievals and climate models) seems reasonable in Delhi only in the pre-monsoon (Mar-Jun) season. During the winter (Dec-Feb) and monsoon (Jul-Sep) seasons, 'WS coating over dust' externally mixed with BC and WINS appears to be the most probable mixing state; while 'WS coating over WINS' externally mixed with BC and dust seems to be the most probable mixing state in the post-monsoon (Oct-Nov) season. Mean seasonal TOA (surface) aerosol DRF for the most probable mixing states are 4.4 +/- 3.9 (- 25.9 +/- 3.9), - 16.3 +/- 5.7 (- 42.4 +/- 10.5), 13.6 +/- 11.4 (-76.6 +/- 16.6) and -5.4 +/- 7.7 (- 80.0 +/- 7.2) W m(-2) respectively in the pre-monsoon, monsoon, post-monsoon and winter seasons. Our results highlight the importance of realistic mixing state treatment in estimating aerosol DRF to aid in policy making to combat climate change

The combined effect of thermal and chemotherapy on HeLa cells using magnetically actuated smart textured fibrous system

Thermal therapy combined with chemotherapy is one of the advanced and efficient methods to eradicate cancer. In this work, we fabricated magnetically actuated smart textured (MAST) fibrous systems and studied their candidacy for cancer treatment. The polycaprolactone-Fe3O4 based MAST fibers were fabricated using electrospinning technique. These MAST fibrous systems contained carbogenic quantum dots as a tracking agent and doxorubicin hydrochloride anticancer drug. Additionally, as fabricated MAST fibrous systems were able to deliver anticancer drug and heat energy simultaneously to kill HeLa cells in a 10 min period in vitro. After treatment, the metabolic activity and morphology of HeLa cells were analyzed. In addition, the mechanism of cell death was studied using flow cytometry. Interestingly, the navigation of these systems in the fluid can be controlled with the application of gradient magnetic field. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 40-51, 2018

Handbook of research on the conservation and restoration of tropical dry forests Practice, progress, and proficiency in sustainability (PPPS) book series./ [edited by] Rahul Bhadouria, Sachchidanand Tripathi, Pratap Srivastava, Pardeep Singh.

Includes bibliographical references and index."This book examines the current trends, issues, and future challenges of conservation strategies for tropical dry forests"--Section 1. Global overview and climate change. Chapter 1. Global overview of tropical dry forests ; Chapter 2. Effect of climate change on tropical dry forests ; Chapter 3. Climate change effects, adaptation, and mitigation techniques in tropical dry forests -- Section 2. Plant functional traits. Chapter 4. Plant functional traits in tropical dry forests: a review ; Chapter 5. An overview of the role of plant functional traits in tropical dry forests -- Section 3. Forest diversity, degradation, and management. Chapter 6. Diversity and distribution of tropical dry forests: a case study from Pudukkottai District of Tamil Nadu, India -- sacred groves ; Chapter 7. Floristic diversity and carbon stock in the dry forests of Chad: the case of Manda national park diversity and carbon sequestration of the Manda National Park Flora ; Chapter 8. Biogeographic and anthropogenic effects on Asian elephants in tropical forests of Sumatra, Indonesia ; Chapter 9. Examining patterns and impacts of forest resource extraction and forest degradation in tropical dry forests ; Chapter 10. Litter production and decomposition in tropical forest ; Chapter 11. Participatory management of tropical dry forests in Benin: case study from the "trois rivières" forest, Borgou Region ; Chapter 12. Issues and challenges for stone mining affected forest area restoration through probiotic interventions -- Section 4. Remote sensing in dry tropical forests. Chapter 13. Scenarios of the tropical dry forest of Purulia District West Bengal: a CA-MARKOV model approach ; Chapter 14. Geospatial solutions for forest management: a case study from Nepal ; Chapter 15. Trends in management of tropical forests: application of remote sensing and geographic information system ; Chapter 16. Forest inventory: challenges, trend, and relevance on conservation and restoration of tropical forests -- Section 5. Forest regeneration and policy. Chapter 17. Post-fire regeneration of Woody species in a colombian tropical dry forest ; Chapter 18. Ecology of natural regeneration of tropical dry forests of Africa and its implications for their sustainable man ; Chapter 19. Role of institutional governance in protecting the natural environment: a case of national capital region, India.1 online resource

Aerosol optical properties and radiative effects over Manora Peak in the Himalayan foothills:Seasonal variability and role of transported aerosols.

The higher altitude regions of Himalayas and Tibetan Plateau are influenced by the dust and black carbon (BC) aerosols from the emissions and long-range transport from the adjoining areas. In this study, we present impacts of advection of polluted air masses of natural and anthropogenic emissions, on aerosol optical and radiative properties at Manora Peak (similar to 2000 m amsl) in central Himalaya over a period of more than two years (February 2006-May 2008). We used the most updated and comprehensive data of chemical and optical properties available in one of the most climatically sensitive region, the Himalaya, to estimate atmospheric radiative forcing and heating rate. Aerosol optical depth (ADD) was found to vary from 0.04 to 0.45 with significantly higher values in summer mainly due to an increase in mineral dust and biomass burning aerosols due to transport. In contrast, single scattering albedo (SSA) varied from 0.74 to 0.88 with relatively lower values during summer, suggesting an increase in absorbing BC and mineral dust aerosols. As a result, a large positive atmospheric radiative forcing (about 28 5 Wm(-2)) and high values of corresponding heating rate (0.80 +/- 0.14 Kday(-1)) has been found during summer. During the entire observation period, radiative forcing at the top of the atmosphere varied from 2 to +14 Wm(-2) and from -3 to -50 Wm(-2) at the surface whereas atmospheric forcing was in the range of 3 to 65 Wm(-2) resulting in a heating rate of 0.1-1.8 Kday(-1)

Identification of aerosol types over Indo-Gangetic Basin: implications to optical properties and associated radiative forcing

The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50 % of all the aerosol types. OCE, on the other hand, contributes only about 12-15 % at all the stations except at Kanpur where its contribution is similar to 38 %. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB

Study of HVDC Controls Through Efficient Dynamic Digital Simulation of Converters

This paper describes the converter model for 6/12 pulse operation and presents its applic ations for the study of the performance of converter controls. The simulation is simplified by representing the converter as a time varying equivalent circuit on the DC side which is derived on the basis of graph theory. Elimination of the need to store connection matrices and an efficient way of generating the converter equations are further innovations introduced here. The converter control based on digital techniques has been considered a long with representation of voltage dependent current order limit. The results of various test simulations considering both weak and strong ac system characteristics are represented to illustrate the simulation capability