Design and Synthesis of Aminoglycoside Antibiotics to Selectively Target 16S Ribosomal RNA Position 1408

The glucopyranosyl moiety (ring I) of paromomycin was modified in a search for novel aminoglycoside antibiotics. The key intermediates were the 4′,6′‐O‐benzylidenated N‐Boc derivative 3 and the azido analogue 18 . The bromobenzoates 4 and 19 were prepared by treating the benzylidene acetals 3 and 18 , respectively, with N‐bromosuccinimide (NBS), and the diol 8 was obtained by hydrogenolysis of 3. The C(6′)‐deoxy derivative 5 was obtained from 4 by treatment with Bu₃SnH. Selective fluorodehydroxylation of 8 gave the fluoro derivative 9. The pseudotrisaccharide 13 was obtained by reductive fragmentaion of the iodo compound 12 obtained from the bromobenzoate 4 . The 3′,6′‐anhydro derivative 20 was obtained upon deacetylation of 19. Standard deprotection gave the C(6′)‐deoxy compound 7 , the fluoro compound 11 , the pseudotrisaccharide 15 , and the 3′,6′‐anhydro‐paromomycin 22 . As compared to paromomycin, the C(6′)‐deoxy and fluorodeoxy derivatives 7 and 11 showed a lower activity against both wild type 1408A and 1408G mutant ribosomes. A lower activity was also found for the 3′,6′‐anhydro derivative 22 and for the pseudotrisaccharide 15 .     

Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO2 nanoparticles

In the present work TiO₂ nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO₂ NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.     

Experimental Techniques for Finite Shear Strain Measurement within Two Advanced High Strength Steels

Experimental Mechanics - There is a growing need to experimentally characterize local shear deformation in advanced high strength steels (AHSS) for the calibration of stress-state dependent...     

A Tachyonic Scalar Field with Mutually Interacting Components

We investigate the tachyonic cosmological potential V(?) in two different cases of the quasi-exponential expansion of universe and discuss various forms of interaction between the two components—matter and the cosmological constant—of the tachyonic scalar field, which lead to the viable solutions of their respective energy densities. The distinction among the interaction forms is shown to appear in the O _m (x) diagnostic. Further, the role of the high- and low-redshift observations of the Hubble parameter is discussed to determine the proportionality constants and hence the correct form of matter–cosmological constant interaction.     

Enhancement of Non-Gaussianity and Nonclassicality of Photon-Added Displaced Fock State: A Quantitative Approach

Non-Gaussian and nonclassical states and processes are already found to be important resources for performing various tasks related to quantum gravity and quantum information processing. Considering these facts, a quantitative analysis of the nonclassical and non-Gaussian features is performed here for photon added displaced Fock state, as a test case, using a set of measures, namely entanglement potential, Wigner–Yanese skew information, Wigner logarithmic negativity, and relative entropy of non-Gaussianity. It is observed that Fock parameter always increases the amount of nonclassicality and non-Gaussianity, while photon addition is effective only for small values of the displacement parameter. Further, the nonclassical and non-Gaussian effects decrease initially with an increase in the displacement parameter before increasing for the large displacement to saturate to the corresponding Fock state (equivalently displaced Fock state) value. Finally, dynamics of the Wigner function under the effect of photon loss channel is used to show that only highly efficient detectors are able to detect Wigner negativity.