Vignan University

About: Vignan University is a education organization based out in Guntur, Andhra Pradesh, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 1138 authors who have published 1381 publications receiving 7798 citations.

Intra and Inter-Species Communication in Microbes: Living with Complex and Sociable Neighbors

Abstract: Quorum sensing is a signaling mechanism wherein the microbes interact with each other through diverse chemical signals, known as auto inducers. Microbes not only synthesize, secrete, detect and respond to the chemical signals but also sense the signals that they do not synthesize in their immediate environment to discriminate their neighbors from others. Intra and inter-species communications between microbes surrounded by biofilm could be antagonistic, such as competition over nutrients and growth inhibition, or synergistic. These comprise the mixed biofilm development by co-aggregation; metabolic cooperation where one species utilizes a metabolite produced by its nearest species, along with augmented resistance to antibiotics or immune responses host. Interestingly bioluminescence, virulence factor expression, antimicrobial resistance, sporing and maturation of microbes also depend on mixed communications. These favourable interactions in mixed biofilms have important environmental, industrial and clinical connotations. The present review emphasizes the current knowledge relating to intra and species auto inducers and their role in activation of genes along with the receptors and signal molecules released by host cells.

Rotation invariant image authentication using Haralick features

Abstract: The image authentication plays a vital role in modern multimedia technology. The existing technique for preserving authentication abided the content only by preserving transformations like scaling, additive noise, gamma correction, brightness adjustments, water marking etc., but it fails to authenticate larger angles rotations. Very few systems had authenticated rotations to a smaller angle which was less than 5o. In existing system, the failure occurred in authenticating large angle rotation is due to the finite divisions of equal sized square block for calculating the local features. In this paper concept of dividing circular blocks with equal area is analyzed for better competency. The Haralick features are mostly calculated for square block. In the proposed system 14 features of Haralick has been grouped to hash code for each circular blocks in sender side. In receiver side, the same procedure is followed to generate hash code and the comparison is carried out to verify the authentication. In addition to scaling, brightness, contrast adjustment, gamma correction etc., the proposed system tolerates rotation even to greater angles up to 360o with better efficiency.

Synthesis of dibenzo[a,d]cycloheptanoids via aryne insertion into 2-arylidene-1,3-indandiones.

Abstract: A novel and unexpected aryne insertion cascade reaction on 2-arylidene-1,3-indandiones via conjugate addition of fluoride followed by formal C–C insertion is developed to afford dibenzo[a,d]cycloheptanoid derivatives in good yields with a single isomer. This reaction represents a rare instance of cyclic enone C–C bond insertion (acyl-alkenylation) in aryne chemistry. Interestingly, 2-arylidene-1,3-indandiones bearing electron rich functional groups provided dibenz[a,c]anthracene-9,14-dione derivatives via [4 + 2] cycloaddition followed by ring expansion.