Cu Shah Science College

Ahmadābād, India

Cu Shah Science College

Ahmadābād, India

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Makwana N.G.,Rc Technical Institute | Prajapati H.R.,Cu Shah Science College | Doshi A.V.,Saurashtra University
Molecular Crystals and Liquid Crystals | Year: 2015

A novel azoester homologous series of liquid crystals consisting of 12 members is majorly nematogenic without the exhibition of smectic mesomorphism, except for the hexadecyloxy derivative. The methoxy and ethoxy members are monotropically nematic and the rest of the homologs are enantiotropically nematogenic. Transition temperatures and mesophase morphology were determined on an optical polarizing microscope equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type. Infra red, 1H NMR, mass spectral data, and elemental analysis data confirm the molecular structures of the novel homologs. The mesophase length varies from 00 to 72°C and the average thermal stability for the nematic phase is 133.5°C. Liquid crystal properties vary from homolog to homolog in present novel series. The liquid crystal behavior of the presently investigated novel series is compared with structurally similar known series. The transition curves (Cr-N/Cr-I and N-I/I-N) behave in a normal manner. The N-I/I-N transition curve exhibit an odd-even effect. The series is majorly nematogenic without exhibition of smectogenic character. Only the C16 homolog is nonmesogenic. © 2015 Taylor & Francis Group, LLC.


Thakore B.Y.,Sardar Patel University | Khambholja S.G.,Sardar Patel University | Suthar P.H.,Cu Shah Science College | Jani A.R.,Sardar Patel University
AIP Conference Proceedings | Year: 2010

Electrical transport properties viz. electrical resistivity, thermoelectric power and thermal conductivity of liquid Al-Cu alloys as a function of Cu concentration have been studied in the present paper. Ashcroft empty core model potential has been used to incorporate the ion-electron interaction. To incorporate the exchange and correlation effects, five different forms of local field correction functions viz. Hartree, Taylor, Ichimaru et al., Farid et al. and Sarkar et al. have been used. The transport properties of binary system have been studied using Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. The computed values of electrical resistivity are compared with experimental data and for low Cu concentration, good agreement has been observed. Further, thermoelectric power and thermal conductivity have also been predicted. © 2010 American Institute of Physics.


Pandya B.M.,Cu Shah Science College | Haider S.A.,Physical Research Laboratory
Planetary and Space Science | Year: 2012

We have analyzed 1500 electron density profiles obtained from radio occultation experiment onboard Mars Global Surveyor to study the physical characteristics of meteoric plasma layers over Mars during the months of JanuaryJune, 2005. It is found that 65 electron density profiles were strongly perturbed with peak densities ∼0.51.4×10 10 m -3 at altitude between 80 km and 105 km probably due to ablation of meteoroids and subsequent ionization of meteoric atoms. These profiles are used to estimate Total Electron Content (TEC) in the lower atmosphere of Mars. Our analysis suggests that meteoroids ablation caused enhancements in TEC by a factor of ∼1.53.0. We also report that maximum TEC were observed on 21 January and 23 May, 2005, when comets 2007 PL42 and 4015 Wilson-Harrington intersected the orbit of Mars from a close distance 1.49 AU and 1.17 AU, respectively. TEC were increased by a factor of ∼57 on these days. This is a significant increase in TEC, which might be associated with the meteor showers that were produced when Mars crossed the dust stream left along the orbit of these comets. © 2011 Elsevier Ltd. All rights reserved.


Jain R.,Physical Research Laboratory | Awasthi A.K.,Physical Research Laboratory | Tripathi S.C.,Barkatullah University | Bhatt N.J.,Cu Shah Science College | Khan P.A.,Barkatullah University
Icarus | Year: 2012

We probe the lethality of X-rays from solar flares to organisms on Mars based on the observations of 10 solar flares. We, firstly, estimate the doses produced by the strong flares observed by the RHESSI and GOES missions during the descending phase of sunspot cycle 23. Next, in order to realize the dependence of dose on flux and steepness of spectra, we model the incident spectra over a wide range of spectral index to estimate dose values and compare them with the observed doses. We calculate the distribution of surficial spectra visible to organisms on the martian surface by employing attenuation of X-rays due to CO 2 column densities distribution over the South Pole. The surficial flux distribution after folding with the opacity of water enables us to estimate the dose distribution over the South Pole. The dose measured from the surficial spectrum produced by the observed 10 flares corresponding to the latitudes 50-60°, 60-70°, 70-80° and 80-90°S varies in the range of 6.39×10 -9-1.80×10 -6; 4.89×10 -10-5.21×10 -8; 5.10×10 -11-5.20×10 -9 and 4.42×10 -10-4.89×10 -12 gray (1 gray=10 4erg/g) respectively. Comparing the measured as well as the modeled doses with those proposed to be lethal for various organisms by Smith and Scalo (Smith, D.S., Scalo, J. [2007]. Planet. Space Sci. 55, 517-527); we report that the habitability of life on the South Pole remains unaffected even by the strongest solar flare occurred during descending phase of solar cycle 23. Further, the monthly integrated energy released by the solar flares in the most productive month viz. October 2003 and January 2005 from the GOES soft X-ray observations is estimated to be 8.43 and 3.32×10 32ergs respectively, which is almost equal in order to the typical energy released by a single strong X-class flare. Therefore, we propose the life near the South Pole region on the Mars remain uninfluenced by X-ray emission even during monster phenomena of energy release on the Sun and/or Star. © 2012 Elsevier Inc.


Haider S.A.,Physical Research Laboratory | Pandya B.M.,Cu Shah Science College | Molina-Cuberos G.J.,University of Murcia
Journal of Geophysical Research: Space Physics | Year: 2013

We report that radio science (RS) experiment onboard Mars Express (MEX) has observed three plasma layers in the nighttime ionosphere of Mars at altitudes ∼80-100 km, ∼120 km, and ∼160 km, which are reproduced by model calculation due to impact of meteoroid, solar wind proton, and electron, respectively. The densities of 21 ions (Mg+, Fe+, Si +, MgO+, MgCO2 +, MgO 2 +, MgN2 +, FeO+, FeO 2 +, FeN2 +, FeCO2 +, SiO+, SiCO2 +, SiN 2 +, SiO2 +, CO2 +, N2 +, O+, O2 +, CO+, and NO+) have been computed between altitude 50 km and 200 km. The model shows that all atmospheric ions (CO 2 +, N2 +, O+, CO +, O2 +, and NO+) are produced above 100 km due to solar wind electron and proton impact ionizations. The metallic ions are formed between 50 km and 100 km due to ablation of micrometeoroids. It is found that mass ∼3.0 × 10-4 g of incoming meteoroid is sufficient for meteor ablation and its characteristic flux ∼4.0 × 10-15 cm-2s-1 could produce the nighttime metallic layer observed by MEX. The calculated electron densities are also compared with the occultation measurements made by Mars 4/5 in the nighttime ionosphere of Mars. Key Points First observation made by MEX in the night time of Mars The model shows that all atmospheric ions are produced in the upper ionosphere The metallic ions are formed between 50 km and 100 km ©2013. American Geophysical Union. All Rights Reserved.


Prajapati H.R.,Cu Shah Science College | Doshi A.V.,Mvm Science And Home Science College
Der Pharma Chemica | Year: 2011

New homologous series with -COO- and -N=N- as central group have been synthesized by the treatment of 4-n-alkoxy benzoyl chloride with 2-Hydroxy -naphthyl - 1 - azo - 4' - nitro benzene. All the homologues of the series are enantiotropically nematogenic without exhibition of smectic mesophase. The texture of nematic mesophase is of threaded type. Well known odd-even effect is clearly observed in the nematic isotropic transition curve. Thermal stabilities and liquid crystalline properties are compared with other structurally identical homologous series. Transition temperatures are observed through hot stage polarizing microscope. Analytical data support the structure of molecules.


Chaube H.A.,Gujarat University | Rana V.A.,Gujarat University | Gadani D.H.,Cu Shah Science College
Philosophical Magazine | Year: 2011

Dielectric properties of binary mixtures of anisole with methanol (MeOH), 1-propanol (1-PrOH), 1-butanol (1-BuOH) and 1-heptanol (1-HeOH) over an entire concentration range have been studied at a fixed temperature 40°C. The dielectric constant (ε′) and dielectric loss (ε″) of the binary mixtures of polar liquids have been determined at a microwave frequency of 9.1 GHz. The static dielectric permittivity (ε 0) of the liquid samples was also determined using a precision LCR meter. Determined values of static dielectric permittivity (ε 0) and dielectric permittivity (ε*) at 9.1GHz frequency were used to evaluate relaxation time (τ) and high frequency limit dielectric permittivity (ε ∞). Dielectric parameters were interpreted in terms of molecular interaction between the anisole and alcohol molecules. © 2011 Taylor & Francis.


Prajapati H.R.,Cu Shah Science College | Doshi A.V.,Saurashtra University
Molecular Crystals and Liquid Crystals | Year: 2015

Novel homologous series 4-(4′-n-alkoxy benzoyloxy) napthyl azo 2″ - nitro benzenes, consisted of eleven members of a series. All the eleven members (methoxy to tetradecyloxy) homologs are only enantiotropically nematogenic without exhibition of any smectogenic character. Transition temperatures and the textures are determined by an optical polarizing microscopy equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Analytical and spectral data supported the molecular structure of homologs. Transition curves viz., solid-nematic and nematic-isotropic showing phase behavior of the mesophase in a phase diagram behave in normal manner. Odd-even effect and alternation of transition temperatures are exhibited by N-I transition curve. N-I thermal stability is 129.7°C and Nematic mesophase vary from 12 to 64°C. Thus, novel series is entirely nematogenic and middle ordered melting type. Mesomorphic behavior of a novel series are compared with the structurally similar homologous series. Copyright © 2015 Taylor & Francis Group, LLC.


Patel D.H.,P.A. College | Prajapati H.R.,Cu Shah Science College | Doshi A.V.,M V M Science And Home Science College
Molecular Crystals and Liquid Crystals | Year: 2016

Eleven homologues of the title series were synthesized. The methyl-to-pentyl derivatives are nonmesomorphic. The nematic mesophase commences from the sixth member of the series without any smectic phase. An odd-even effect in the nematic-isotropic transition curve is not observed. The nematic mesophase appeared as a threaded or a Schlieren-type texture as observed through a hot-stage polarizing microscope. The nematic-isotropic transition temperatures are between 89°C and 127°C with the mesomorphic range varying from 9°C to 44°C at the hexyl and tetradecyl derivative of the series, respectively. The nematic-isotropic transition curve initially rises and then falls in a normal manner as the series is ascended, but it abnormally rises beyond the 10th homologue. The series is enantiotropic nematic with a middle-ordered melting type. Analytical data support the structures of the molecules. The thermal stability and some other mesomorphic characteristics are compared with structurally similar homologous series. The average nematic-isotropic thermal stability is 105.4°C. © 2016 Taylor and Francis Group, LLC.


Prajapati H.R.,Cu Shah Science College | Doshi A.V.,Cu Shah Science College | Doshi A.V.,Saurashtra University
Molecular Crystals and Liquid Crystals | Year: 2015

The synthesis of a novel azoester homologous series was carried out with a view to understanding and establishing the effect of molecular structure on liquid crystal (LC) behavior of a substance. The novel series consists of eleven homologs, and all are enantiotropically nematogenic without exhibition of any smectic property. Transition and melting temperatures, textures of LC were determined by an optical polarizing microscope equipped with a heating stage. The textures of the nematic phase are threaded or Schlieren. Transition curves of a phase diagram behave in normal manner. The nematic-isotropic transition curve exhibits an odd-even effect. Analytical and spectral data support and confirm the structures of the homologues. Average thermal stability for the nematic is 137.2°C. The mesomorphic phase length ranges from 15°C to 50°C. LC behavior of the novel series is compared with a structurally similar known homologous series. The novel azoester homologous series is entirely nematogenic without exhibition of smectogenic character and of a middle-ordered melting type. Copyright © Taylor & Francis Group, LLC 2015.

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