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Rajiv Kumar

Bio: Rajiv Kumar is an academic researcher from Jaypee University of Information Technology. The author has contributed to research in topics: Catalysis & Molecular sieve. The author has an hindex of 51, co-authored 561 publications receiving 15404 citations. Previous affiliations of Rajiv Kumar include University of Kashmir & Central Building Research Institute.


Papers
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TL;DR: It is observed that aqueous silver ions when exposed to the fungus Fusarium oxysporum are reduced in solution, thereby leading to the formation of an extremely stable silver hydrosol, creating the possibility of developing a rational, fungal-based method for the synthesis of nanomaterials over a range of chemical compositions, which is currently not possible by other microbe-based methods.

1,765 citations

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TL;DR: Electron microscopy analysis of thin sections of the fungal cells indicated that the silver particles were formed below the cell wall surface, possibly due to reduction of the metal ions by enzymes present in the cell walls membrane.
Abstract: A novel biological method for the synthesis of silver nanoparticles using the fungus Verticillium is reported. Exposure of the fungal biomass to aqueous Ag+ ions resulted in the intracellular reduction of the metal ions and formation of silver nanoparticles of dimensions 25 ± 12 nm. Electron microscopy analysis of thin sections of the fungal cells indicated that the silver particles were formed below the cell wall surface, possibly due to reduction of the metal ions by enzymes present in the cell wall membrane. The metal ions were not toxic to the fungal cells and the cells continued to multiply after biosynthesis of the silver nanoparticles.

1,207 citations

Journal Article
TL;DR: An overview of the research efforts worldwide on the use of micro-organisms in the biosynthesis of inorganic nanoparticles, with particular emphasis on the recent and exciting results obtained at the National Chemical Laboratory, Pune on the biosynthetic of noble-metal nanoparticles using fungi and actinomycete is provided.
Abstract: There is little doubt that nanomaterials will play a key role in many technologies of the future. One key aspect of nanotechnology concerns the development of reliable experimental protocols for the synthesis of nanomaterials over a range of chemical compositions, sizes and high monodispersity. In the context of the current drive to develop green technologies in materials synthesis, this aspect of nanotechnology assumes considerable importance. An attractive possibility is to use micro-organisms in the synthesis of nanoparticles. In this article, we provide a brief overview of the research efforts worldwide on the use of micro-organisms in the biosynthesis of inorganic nanoparticles, with particular emphasis on the recent and exciting results obtained at the National Chemical Laboratory, Pune on the biosynthesis of noble-metal nanoparticles using fungi and actinomycete. Some of the challenges in this emerging approach are highlighted.

921 citations

Journal ArticleDOI
TL;DR: A green-chemistry route, based on the bioreduction of AuCl 4 - ions by the fungus Verticillium sp.
Abstract: Fungi make piles of gold! A green-chemistry route, based on the bioreduction of AuCl 4 - ions by the fungus Verticillium sp., for the formation of gold nanoparticles is demonstrated. The TEM micrograph shows a single Verticillium cell after reaction with gold ions and entrapment of gold nanoparticles on the cell wall and cytoplasmic membrane.

791 citations


Cited by
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TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

11,752 citations

Christopher M. Bishop1
01 Jan 2006
TL;DR: Probability distributions of linear models for regression and classification are given in this article, along with a discussion of combining models and combining models in the context of machine learning and classification.
Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

10,141 citations

Journal ArticleDOI
TL;DR: Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting and its Applications d0 Metal Oxide Photocatalysts 6518 4.4.1.
Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

6,332 citations