The Hindu College

Machlipatnam, India

The Hindu College

Machlipatnam, India
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Murthy C.S.V.S.,The Hindu College | Pardhasaradhi P.,Koneru Lakshmaiah College of Engineering | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
Liquid Crystals Today | Year: 2016

As a part of our systematic studies on liquid crystal dimers, we present in this article the nature of phase transitions across isotropic–nematic and nematic–smectic-A exhibited by DLCs, α,ω-bis-(4-n-alkylaniline benzylidene-4ʹ-oxy) alkanes. Further, the orientational order parameter in the nematic phase of these DLCs are estimated from the molecular polarisabilities calculated using the experimental refractive indices and density results. The molecular polarisabilities αe and αo are obtained for the compounds using the above results for both Vuks and Neugebauer local field models applicable to nematic liquid crystal. αe and αo calculated in this way are used to obtain Δα. The polarisability anisotropy in the perfect order (absolute K) is calculated semi-empirically using the δ-function model developed by Lippincott et al. and molecular vibration method. The values of polarisability anisotropy for both local electric field models differ significantly. No criterion is known to decide which value is correct. To avoid the determination of uncertain α and Δα values considering different local field models, a simple procedure developed by Kuczynski et al. was used for evaluation of S, based solely on birefringence δn = (ne-no) and this value of S is compared with those obtained from field models. © 2015 Taylor & Francis.


Madhavi Latha D.,Koneru Lakshmaiah College of Engineering | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering | Pardhasaradhi P.,The Hindu College | Datta Prasad P.V.,The Hindu College | Padmaja Rani G.,Jawaharlal Nehru Technological University Kakinada
Liquid Crystals | Year: 2012

The temperature gradient of refractive indices, dn e/dT and dn o/dT of a number of liquid crystals of different homologous series are analysed. It was found that the materials studied possess high clearing temperatures and the cross over temperatures estimated are well above room temperature and they show an odd-even effect with the chain length in a homologous series. © 2012 Copyright Taylor and Francis Group, LLC.


Devi G.S.,The Hindu College | Devi G.S.,JMJ College | Prasad P.V.D.,The Hindu College | Latha D.M.,Koneru Lakshmaiah College of Engineering | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
Liquid Crystals | Year: 2013

The effective geometry parameter, αg = no /ne, is used to evaluate the orientational order parameter, S, in the case of N-(p-n-butyloxybenzylidene)-p-n-alkoxy anilines, 4O.Om and N-(p-n-heptyloxybenzylidene)-p-n-alkoxy anilines, 7O.Om compounds with m = 3-7 and 9 in the former case and m = 3, 5-7 and 9 in the later materials. The results obtained are compared with those calculated using the standard techniques of molecular polarisability and birefringence. The effective geometry parameter's influence on the deflection of light by the liquid crystal compounds is also studied. The variation of temperature gradient of the ordinary refractive index, dno /dT, and extraordinary refractive index, dn e /dT, of the liquid crystals is also studied. © 2013 Copyright Taylor and Francis Group, LLC.


Madhav B.T.P.,Koneru Lakshmaiah College of Engineering | Pardhasaradhi P.,Koneru Lakshmaiah College of Engineering | Manepalli R.K.N.R.,The Hindu College | Kishore P.V.V.,Koneru Lakshmaiah College of Engineering | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
Liquid Crystals | Year: 2015

Low contrast and noisy photographic pictures can be considerably improved by image-processing techniques. Techniques like histogram equalisation produce high-contrast images but often fail to preserve the colour texture information. To overcome this deficiency, a contrast-enhancement approach has been devised, using virtual contrast image fusion (in Haar wavelet domain). This technique has been evaluated by a study of the optical textures of nano-dispersed decyloxybenzoic acid with small quantities of Fe3O4 and ZnO added. © 2015 Taylor & Francis


Manepalli R.K.N.R.,The Hindu College | Pardhasaradhi P.,Koneru Lakshmaiah College of Engineering | Madhav B.T.P.,Koneru Lakshmaiah College of Engineering | Jayaprada P.,Krishna Institute of Engineering and Technology | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
International Journal of Earth Sciences and Engineering | Year: 2016

Synthesis and characterisation are carried out on four N-(p-n-decyloxy benzylidene-)p-n-alkoxy anilines 10O.Om Liquid Crystalline compounds(LC) with n=10 and m=3, 5 and with 1% ZnO nano particle dispersion. Further to reduce the multiplicative noise a component of the image is separated linearly in the frequency domain, Homomorphic Filtering technique is used. This technique provides frequency domain procedure to improve the appearance of an image by gray level range compression and contrast enhancement. Textures of the compounds are recorded with polarising microscope connected with hot stage and camera, the illumination and reflectance combined multiplicatively and the image quality is reduced to identify the exact phase in the compound. The compounds with m=3 exhibits NACB phases and m=5 exhibits NACIG, while with a nano dispersion of ZnO exhibits the same phases with reduced clearing temperature as expected when the doping is done with 1%. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.


Madhav B.T.P.,Koneru Lakshmaiah College of Engineering | Pardhasaradhi P.,Koneru Lakshmaiah College of Engineering | Kishore P.V.V.,Koneru Lakshmaiah College of Engineering | Manepalli R.K.N.R.,The Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
Liquid Crystals Today | Year: 2016

The main objective of the image enhancement is to process an image with suitable technique to produce better visibility for a specific application. To identify key features like transition temperatures, clear phase identification in the liquid crystalline images, we require some novel image processing techniques. Characterisation and mesomorphic behaviour in pure and 1% ZnO nano-dispersed liquid crystalline N-(p-n-decyloxybenzylidene)-p-n-hexyloxy anilines, 10O.O6 compounds are carried out using a polarising microscope and images are preserved for enhancement. Both the compounds exhibits NACIG (nematic, smectic-A, smectic-C, smectic-I, smectic-G) phases and the transition temperatures of the 1% ZnO nano-dispersed 10O.O6 are reduced compared with pure 10O.O6. Further, in this paper, a novel image enhancement technique of combined unsharp masking is proposed on pure and 1% ZnO nano-dispersed 10O.O6 liquid crystalline compounds for better visibility of phases at transition temperatures. The proposed method is used to identify the uniform regions and to detect the defects which may not be clearly observed from the textures that are recorded by polarising microscope. © 2016 Informa UK Limited, trading as Taylor & Francis Group.


Madhav B.T.P.,Koneru Lakshmaiah College of Engineering | Pardhasaradhi P.,Koneru Lakshmaiah College of Engineering | Manepalli R.K.N.R.,The Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering
Liquid Crystals | Year: 2015

The 1% Fe3O4 nanodoped in dodecyloxy benzoic acid induces cholesteric phase quenching the nematic phase that the pure compound exhibits. Further, the solid–solid transition also occurs when compared to the pure compound and the transition temperatures are reduced along with the cholesteric thermal ranges of LC phases. The histogram is the operation by which the occurrences of intensity value in the image is shown. Further, histogram equalisation is the technique through which the dynamic range of the histogram of an image can be increased. Histogram equalisation method is used in this article to analyse the 12Oba + 1% Fe3O4 nanodoped liquid crystalline textures by considering global and local image information and for the adjustment of image intensities to enhance the contrast. The basic idea of histogram equalisation is to remap the grey levels of the image, and this method is used to identify the uniform regions and detect the defects that are not clearly observed from the textures that are recorded by polarising microscope. © 2015 Taylor & Francis.


Pisipati V.G.M.,Koneru Lakshmaiah University | Latha D.M.,Koneru Lakshmaiah University | Madhav B.T.P.,Koneru Lakshmaiah University | Datta Prasad P.V.,The Hindu College
Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences | Year: 2010

The tri critical point (TCP), where the second-order transition transforms to first order has been located in nO.m homologous series. The order parameter has been estimated from the birefringence δn, from the refractive indices and from birefringence data available in literature and from those obtained at our laboratory on a number of nO.m compounds. The compounds in the nO.m series exhibit both second and first-order nematic/smectic-A (NSA) transition depending on the McMillan ratio (TNA/TIN) which in turn depends on the nematic and smectic-A thermal ranges. The data presented are compared with the body of the data available on this homologous series obtained with other techniques. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen.

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