Deviation problems in ray optics in the light of the refined unambiguous definitions of angles of incidence,reflection and refraction

This paper makes use of the newly introduced refined unambiguous definitions of angle of incidence, angle of reflection and angle of refraction to give birth to novel vectorial treatment for the calculation of deviation of a ray of light in each of a few cases of ray optics. The problem of calculation of minimum deviation of a ray of light in passing through a prism has also been considered in the light of the refined unambiguous definitions of angle of incidence and angle of refraction. The use of vectorial treatment increases the range of applicability of vector algebra. Furthermore, incorporation of the refined unambiguous definitions of the aforesaid three angles in the novel treatment offered is much clearer leaving no room for confusion and it will enhance and sophisticate the optical field.     

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Optical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4′-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4′-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.     

Zeolitic Imidazolate Frameworks: Synthesis,Functionalization, and Catalytic/Adsorption Applications

Zeolitic imidazolate frameworks (ZIFs) are comprised of transition metal ions (Zn, Co) and a range of imidazolate linkers in a tetrahedral coordination similar to that in crystalline aluminosilicate zeolites. The high surface area, tunable nanoporosity that can be subject to functionalization and the excellent thermal/chemical stability of ZIFs are attractive for heterogeneous catalysis and selective gas adsorption/separation. This review presents the current trends in synthesis, surface modification and catalytic reactions/adsorption of ZIF-based materials with particular emphasis on ZIF-8, which is the most widely studied structure among ZIFs.     

Deformation of a droplet in an electric field: nonlinear transient response in perfect and leaky dielectric media

Deformation of a fluid drop, suspended in a second immiscible fluid, under the influence of an imposed electric field is a widely studied phenomenon. In this paper, the system is analyzed numerically to assess its dynamic behavior. The response of the system to a step change in the electric field is simulated for both perfect and leaky dielectric systems, exploring the influence of the fluid, interfacial, and electrical properties on the system dynamics. For the leaky dielectric case, the dynamic build up of the free charge at the interface, including the effects of convection along the interface due to electrohydrodynamic circulation, is investigated. The departure of the system from linear perturbation theory is explained using these dynamic simulations. The present simulations are compared with analytic solutions, as well as available experimental results, indicating that the predictions from the model are reliable even at considerably large deformations.     

Tunable filtration media employing alternating current electrokinetics

Separation of colloidal particles from aqueous media by barrier filtration is typically dictated by sieving mechanisms. Here, we demonstrate that colloid filtration by porous membranes can be considerably augmented by suitably superimposing an alternating current (AC) electric field on the membrane. The combined steric-dielectrophoretic filtration can result in very high rejection of the particles compared to solely steric rejection.     

Helicity induction through hydrogen bonding and spontaneous resolution of a bimetallic nickel complex coordinated to an octahedral metalloligand

A new bimetallic complex of nickel(II) coordinated to a molybdenum-containing metalloligand has been synthesized that forms a helical chain through hydrogen bonding and shows spontaneous resolution upon crystallization.     

In Vitro Renaturation of Alkaline Family G/11 Xylanase via a Folding Intermediate: α-Crystallin Facilitates Refolding in an ATP-Independent Manner

In this study, alkaliphilic family G/11 xylanase from alkali-tolerant filamentous fungi Penicillium citrinum MTCC 6489 was used as a model system to gain insight into the molecular aspects of unfolding/refolding of alkaliphilic glycosyl hydrolase protein family. The intrinsic protein fluorescence suggested a putative intermediate state of protein in presence of 2 M guanidium hydrochloride (GdmCl) with an emission maximum of 353 nm. Here we studied the refolding of GdmCl-denatured alkaline xylanase in the presence and the absence of a multimeric chaperone protein α-crystallin to elucidate the molecular mechanism of intramolecular interactions of the alkaliphilic xylanase protein that dictates its extremophilic character. Our results, based on intrinsic tryptophan fluorescence and hydrophobic fluorophore 8-anilino-1- naphthalene sulfonate-binding studies, suggest that α-crystallin formed a complex with a putative molten globule-like intermediate in the refolding pathway of xylanase in an ATP-independent manner. A 2 M GdmCl is sufficient to denature alkaline xylanase completely. The hydrodynamic radius (R_H) of a native alkaline xylanase is 4.0, which becomes 5.0 in the presence of 2 M GdmCl whereas in presence of the higher concentration of GdmCl R_H value was shifted to 100, indicating the aggregation of denatured xylanase. The α-crystallin·xylanase complex exhibited the recovery of functional activity with the extent of ~43%. Addition of ATP to the complex did not show any significant effect on activity recovery of the denatured protein.     

Rigid extensions of algebraic frames

An extension G ≤ H of lattice-ordered groups is said to be a rigid extension if for each ${h \in H}An extension G ≤ H of lattice-ordered groups is said to be a rigid extension if for each h ? H{h \in H} there exists a g ? G{g \in G} such that h ^⊥⊥ = g ^⊥⊥. In this paper, we will define rigid extensions and some other generalizations in the context of algebraic frames satisfying the FIP. One of the main results is a characterization of rigid extensions using d-elements of the frame. We also show that a rigid extension between two algebraic frames satisfying the FIP will induce a homeomorphism between their corresponding minimal prime spaces with respect to both the hull-kernel topology and the inverse topology. Moreover, basic open sets map to basic open sets.