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1,168 results on '"Bhatnagar, D."'

256. Structural, Dielectric and Magnetic Behavior of Nanocrystalline Zinc Substituted Magnesium Ferrite.

Author

Jyoti, Parashar, Jyoti, Saxena, V. K., Dolia, S. N., Bhatnagar, D., Kumar, S., and Sharma, K. B.

Subjects
ZINC compounds, NANOCRYSTALS, SUBSTITUTION reactions, MAGNESIUM compounds, MAGNETIC properties of metals, DIELECTRIC properties
Abstract

Zinc substituted magnesium ferrites Zn0.2Mg0.8Fe2O4 and Zn0.4Mg0.6Fe2O4 were prepared by sol-gel auto combustion method. Rietveld profile refinement of the XRD patterns confirms the formation of a cubic spinel structure in single phase. The dielectric properties viz. dielectric constant and dielectric loss tangent tanS increase with increasing temperature. The dielectric behavior is explained by using the mechanism of polarization process, which is correlated to that of electron exchange interaction. The saturation magnetization, coercivity and remanent magnetization decreases appreciably with increase in Zn which could be attributed to change in cation distribution. [ABSTRACT FROM AUTHOR]

Published
2015
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275. Transcriptome Analysis of Aspergillus flavusReveals veA-Dependent Regulation of Secondary Metabolite Gene Clusters, Including the Novel Aflavarin Cluster

Author

Cary, J. W., Han, Z., Yin, Y., Lohmar, J. M., Shantappa, S., Harris-Coward, P. Y., Mack, B., Ehrlich, K. C., Wei, Q., Arroyo-Manzanares, N., Uka, V., Vanhaecke, L., Bhatnagar, D., Yu, J., Nierman, W. C., Johns, M. A., Sorensen, D., Shen, H., De Saeger, S., Diana Di Mavungu, J., and Calvo, A. M.

Abstract

ABSTRACTThe global regulatory veAgene governs development and secondary metabolism in numerous fungal species, including Aspergillus flavus. This is especially relevant since A. flavusinfects crops of agricultural importance worldwide, contaminating them with potent mycotoxins. The most well-known are aflatoxins, which are cytotoxic and carcinogenic polyketide compounds. The production of aflatoxins and the expression of genes implicated in the production of these mycotoxins are veAdependent. The genes responsible for the synthesis of aflatoxins are clustered, a signature common for genes involved in fungal secondary metabolism. Studies of the A. flavusgenome revealed many gene clusters possibly connected to the synthesis of secondary metabolites. Many of these metabolites are still unknown, or the association between a known metabolite and a particular gene cluster has not yet been established. In the present transcriptome study, we show that veAis necessary for the expression of a large number of genes. Twenty-eight out of the predicted 56 secondary metabolite gene clusters include at least one gene that is differentially expressed depending on presence or absence of veA. One of the clusters under the influence of veAis cluster 39. The absence of veAresults in a downregulation of the five genes found within this cluster. Interestingly, our results indicate that the cluster is expressed mainly in sclerotia. Chemical analysis of sclerotial extracts revealed that cluster 39 is responsible for the production of aflavarin.

Published
2015
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278. Coronary risk factors in people from the Indian subcontinent living in West London and their siblings in India

Author

Patel, D.J., primary, Winterbotham, M., additional, Britt, R.P., additional, Sutton, G.C., additional, Bhatnagar, D., additional, Mackness, M.I., additional, Creed, F., additional, Tomenson, B., additional, Durrington, P.N., additional, Anand, I.S., additional, Wander, G.S., additional, Chandrashekhar, Y., additional, and Keil, J.E., additional

Published
1995
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283. HYPERSPECTRAL IMAGE CLASSIFICATION AND DEVELOPMENT OF FLUORESCENCE INDEX FOR SINGLE CORN KERNELS INFECTED WITH ASPERGILLUS FLAVUS.

Author

H. Yao, Hruska, Z., Kincaid, R., Brown, R. L., Bhatnagar, D., and Cleveland, T. E.

Subjects
CORN research, AFLATOXINS, HYPERSPECTRAL imaging systems, FLUORESCENCE, ASPERGILLUS flavus
Abstract

Aflatoxins are toxic secondary metabolites predominantly produced by the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxin-contaminated corn is toxic to domestic animals when ingested in feed and is a known carcinogen associated with liver and lung cancer in humans. Consequently, aflatoxin levels in food and feed are regulated by the U.S. Food and Drug Administration (FDA), which allows 20 ppb (parts per billion) limits in food and 100 ppb in feed for interstate commerce. Currently, aflatoxin detection and quantification methods are based on analytical tests, including thin-layer chromatography (TCL) and high-performance liquid chromatography (HPLC). These analytical tests require the destruction of samples and are costly and time consuming. Thus, the ability to detect aflatoxin in a rapid, nondestructive way is crucial to the grain industry, particularly the corn industry. Hyperspectral imaging technology offers a non-invasive approach to screening for food safety inspection and quality control based on spectral signatures. The focus of this study was to classify aflatoxin-contaminated single corn kernels using fluorescence hyperspectral imagery. Fieldinoculated corn kernels were used in the study. Contaminated and control kernels under long-wavelength ultraviolet excitation were imaged using a visible near-infrared (VNIR) hyperspectral camera. The imaged kernels were chemically analyzed to provide reference information for image analysis. This article describes a procedure for processing corn kernels located in different images for statistical training and classification. Two classification algorithms (maximum likelihood and binary encoding) were used to classify each corn kernel as "control" or "contaminated" through pixel classification. The binary encoding approach had a slightly better performance, with accuracy equal to 87% or 88% when 20 ppb or 100 ppb, respectively, was used as the classification threshold. In addition, three narrow-band fluorescence indices were developed and tested in this study. It was found that the highest correlation was -0.81 with the normalized difference fluorescence index (NDFI). The two bands used for the NDFI were 437 and 537 nm. The use of key wavelengths for contamination detection would be helpful for developing rapid and non-invasive inspection systems. This study demonstrated the potential of using fluorescence hyperspectral imagery for aflatoxin contamination detection in corn kernels infected with A. flavus. [ABSTRACT FROM AUTHOR]

Published
2013
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