Optimizing Sonication and Chromatography Conditions in the Purification of LGN Protein for X-Ray Crystallography

LGN protein is a critical component for the division of mammalian cells, as it functions in the maintenance of cell polarity and the alignment of mitotic spindles during mitosis. In order to optimize a purification scheme for LGN, the protein is first expressed in E. coli, and then is sonicated and centrifuged to respectively lyse and separate the cells and other debris from the expressed proteins. Afterwards, the protein mixture is passed through chromatography columns and the LGN protein is assessed for purity using SDS-PAGE, followed by Western blotting to verify the presence of LGN. The goal of the purification scheme is to attain samples of LGN protein at least 95% pure in order for crystallization conditions to be determined for X-ray crystallography. Western blot detection has verified the expression of LGN and the sonication and chromatography conditions are currently being optimized in order to obtain pure LGN

Dielectric Study of Nematic LC Built with Bent-Core Molecules

Here we report results of the study of bent-core (BC) cybotactic nematic LC by dielectric spectroscopy and electro-optic measurements. In the absence of electric field, this material is uniaxial and exhibits only one relaxation process corresponding to the fluctuations of the polar clusters. The application of the external electric field induces biaxialityandthesecondrelaxationprocessappearsinthedielectricspectra.Thisisassigned to the collective mode. Possible models for cluster transformation under electric field are discussed

The NTB phase in an achiral asymmetrical bent-core liquid crystal terminated with symmetric alkyl chains

The characteristics of the twist-bend nematic (NTB) phase of an achiral asymmetrical rigid bent-core liquid crystal (LC), the ends of which are terminated by symmetric alkyl chains, are reported. The nematic�nematic phase transition and its properties are studied by differential scanning calorimetry (DSC), polarising microscopy and the electro-optic techniques. Large domains of opposite handedness are observed in the absence of the external field in the NTB phase. Another set of periodic striped pattern consisting of domains with sharp boundaries is formed when a high-frequency electric field with a magnitude above its threshold is applied across a planarly aligned cell. The neighbouring domains are of opposite chirality. The temperature dependence of the heliconical angle θ0 is determined from the birefringence measurements using Haller�s extrapolation technique. This material shows lower values of the heliconical angle (~9.3° at a temperature of 155°C within the NTB phase) when compared with the previously reported dimer-based twist-bend nematic LCs (31°±3°). © 2016 Informa UK Limited, trading as Taylor & Francis Group

Development of Ferroelectricity in the Smectic Phases of 4-Cyanoresorcinol Derived Achiral Bent-Core Liquid Crystals with Long Terminal Alkyl Chains

Bent-core molecules can form numerous polar and symmetry broken liquid crystalline phases with fascinating properties. Here we report the characteristics of a previously unknown polar synclinic smectic phase, Sm C S P X , found in the phase sequence of an achiral bent-core material with a 4-cyanoresorcinol bisbenzoate core, terminated by long linear alkyl chains ( n = 18 ) on both ends. This phase exists over a narrow range of temperatures and is sandwiched in between the random polar synclinic smectic phase ( Sm C S P R ) and polar synclinic ferroelectric ( Sm C S P F ) phase with P S ∼ 250 nC / c m 2 . In a planar-aligned cell it exhibits only chirality flipping on application of a conventional ac field but it also exhibits optical switching by rotation of the molecular directors on the tilt cone subjected to a modified sequence of bipolar pulses. This changeover is discussed in terms of the model given by Nakata et al. [Phys. Rev. Lett. 96, 067802 (2006)], involving a competition between the two forms of switching: the rotation around the long molecular axis and the switching through rotation of the molecular directors on the tilt cone. The model is modified to take account of the azimuthal pretilt and the molecular tilt angles. In addition to it, characteristics of Sm C S P R are also discussed

Dust Near Galactic HII Regions

The distributions of physical properties, such as the temperature, mass, or density of the dust grains in molecular clouds near Galactic massive star forming regions are relatively poorly understood. These properties are significant in characterizing the early stages of high-mass star formation. The major goal of this thesis is to study the dust properties using continuum emission to learn about the effect on the dust of the extreme environments around high-mass star formation. For this we estimate mass, temperature and luminosity of the hot (≥ 100 K), cool (20-40 K) and cold (≤ 20 K) dust in the environs of Galactic HⅡ regions using Infrared Astronomy Satellite (IRAS) and James Clerk Maxwell (JCMT) Submillimeter Common User Bolometer Arrays (SCUBA & SCUBA-2) data.  A total of 83 clouds has been examined using IRAS data. A two-component model Spectral Energy Distribution (SED) of hot and cool dust is used to fit the IRAS data. A three-component model SED is fitted to combined SCUBA and IRAS data for 15 clouds near HⅡ regions to measure the cold dust component. Surprisingly, the ratio of the bolometric luminosity of the cool dust to the hot dust appears to have the same value 2.8 in virtually all objects. The cool dust has typically four to five orders of magnitude greater mass than the hot dust. However, the mass in cold dust is much greater than the mass in cool and hot dust. These results may prove useful for using IR observations for estimating gas masses in extragalactic systems with active high-mass star formation.
 
The clouds in the environments of HⅡ regions are modelled assuming a thermal equilibrium in large grains, ignoring small grains and polycyclic aromatic hydrocarbons (PAHs). A number of different models having varying density distributions and external stellar radiation are compared to the IRAS SEDs. The model results suggest that the assumptions are not valid. We need a larger amount of dust at 30 K than the models produced and in this thesis we propose a solution to this problem, which we have not yet tested. 

The JCMT Submillimeter Common User Bolometer Array-2 (SCUBA-2) data of six complexes is used to analyze the cold dust near Galactic HⅡ regions. Dust physical property maps such as the temperature, optical depth, column density and visual extinction are constructed from the SCUBA-2 data at 450 and 850 μm wavelengths. All of the molecular cloud cores are found to be at very low temperatures, down to 6 K at the centres, with increasing values toward the periphery. This is surprising because we expected some internal heating at the centre. The column densities at the centres of the clouds exceed 10²³ cm⁻² and the derived peak visual extinction values of most of the cloud cores are above 100, indicating a highly opaque cloud centre. The observed clouds are massive with gas masses ranging from 10² to over 10⁴ M⊙. All of these properties together suggest that the cores are high-mass starless cores (HMSCs), which are not hosting any massive stars at the centre. Note that there are only a few such observations, on these potential precursors of high-mass proto-stellar objects, by others. From the derived physical properties such as high column densities, high visual extinction and the cold temperatures toward the centres of the cores, we speculate that the all the sample cores are in a state of collapse. Note that the Jeans masses of the clouds are much less than their real cloud masses and the free fall times range from 10³ to 10⁴ years, confirming the potential state of the cores.1 yea

Trends and Challenges of India’s Balance of Payments

Balance of Payments (BoP), being a record of the monetary transactions over a period with the rest of the world, reflects all payments and liabilities to foreigners and all payments and obligations received from foreigners. In this sense, the balance of payments is one of the major indicators of a country's status in international trade. BoP accounting serves to highlight a country's competitive strengths and weaknesses and helps in achieving balanced economic-growth. It can significantly affect the economic policies of a government and the economy itself. Therefore, every country strives to a have a favorable balance of payments and maintains its long run sustainability. India’s balance of payment position was quite unfavorable during the time of country’s entry into liberalized trade regime. Two decades of economic reforms and free trade opened several opportunities that, of course, reflected in the balance of payments performance of the country. This paper, therefore, attempts to evaluate the trends and emerging challenges of India’s Balance of Payments. The discussion is broadly classified into four parts viz. i) India’s balance of payments picture since 1991, ii) emerging role of invisibles and software services in balance of payments iii) unhealthy trends in FDI and iv) the vulnerability and challenges ahead

An Artificial Heme Enzyme for Cyclopropanation Reactions

An artificial heme enzyme was created through self-assembly from hemin and the lactococcal multidrug resistance regulator (LmrR). The crystal structure shows the heme bound inside the hydrophobic pore of the protein, where it appears inaccessible for substrates. However, good catalytic activity and moderate enantioselectivity was observed in an abiological cyclopropanation reaction. We propose that the dynamic nature of the structure of the LmrR protein is key to the observed activity. This was supported by molecular dynamics simulations, which showed transient formation of opened conformations that allow the binding of substrates and the formation of pre-catalytic structures

The Global Financial Crisis and its Impact on India’s External Sector

The term financial crisis refers to the loss of confidence in a country's currency or other financial assets causing international investors to withdraw their funds from the country. The financial crisis and associated recession originated in the US in early 2008 and then spread to Europe has by now engulfed most of the economies in both developed and developing world. There is every possibility of direct as well as indirect implications of the crisis on all the economies of the world. The crisis has affected the entire global economies in one way or other. The present study makes an attempt to identify the immediate impact of the financial crisis on major world economies especially Indian economy in terms of selected economic indicators. The study examines the trends in export, import, foreign remittances, earnings from business services, overall Balance of Payment position, GDP growth rates etc in the context of Indian economy against the background of global financial crisis and subsequent global recession. India is considered to be highly vulnerable to a crisis like this because of its greater integration with the rest of the world. The study shows that there are some reasons to believe that the financial crisis affected Indian economy adversely by slowing foreign remittances, foreign investment, adverse BoP position etc. However, Indian economy shows the symptoms of rapid recovery from the sudden set back it had to undergo during 2008-09

A fast linear electro-optical effect in a non-chiral bent-core liquid crystal

We report the observation of an electro-optical effect for a linear rotation of the optical axis as function of the electric field in an achiral tilted bent-core liquid crystalline compound, in which 4-cyanoresorcinol bisbenzoate core is symmetrically terminated by long linear alkyl chains (n =16) on both ends. The linear electro-optic effect observed in this material is similar to the deformed helical ferroelectric liquid crystal (DHFLC) effect reported previously in a FLC material except that dimensions of the helical pitch differ by two orders of magnitude. In the chiral systems, the helical pitch usually lies on the scale of sub-optical wavelength, ~0.3 m depending on the material and temperature, whereas in the achiral system, the pitch lies on the nm scale. The DHFLC mode shows fast, analog switching due to a gradual distortion of the uniform helical structure by the electric field; the switching speed is faster than for the chiral systems. In contrast to the chiral FLCs, achiral liquid crystalline materials appear as better candidates for applications in displays and the photonic technologies

Occurrence of Five Different Orthogonal Smectic Phases in a Bent-Core (BC) Liquid Crystal

Five orthogonal smectic phases (Sm-A, Sm-Ab, Sm-APR, Sm-APAR, and Sm-APA) were observed in a 4-cyanoresorcinol bisbenzoate with twoterephthalate–based wings achiral bent-core(BC) compound. The phase behavior was investigated by polarising optical microscopy, second harmonic electro-optic response(EO2) and dielectric spectroscopy. The field dependent biaxiality of polar and non-polar Sm-A phases was studied. It is obviously of enormous scientific significance and practical interest to find five different orthogonal smectic phases in a low molecular weight bent-core (BC) compound at relatively low temperatures