Sodium-ion binding to DNA: detection by ultrafast time-resolved stokes-shift spectroscopy

The nature of the counterion is shown to have a pronounced effect on the apparent dynamic polarity in the interior of DNA. Time-resolved Stokes-shift measurements in the 80 ps to 40 ns time range were made on a polarity-sensitive fluorophore (coumarin 102) that replaces a base pair in an oligonucleotide. With sodium counterions, the emission spectrum narrows with time, whereas with tetrabutylammonium counterions, it does not. Our interpretation is that a subpopulation of helices have sodium cations bound in a fashion that slows the normal dynamics.     

Studies on satellite and ground-based measurements of aerosols over urban environment

EP/TOMS satellite-derived aerosol index (AI) data have been analyzed over typical tropical urban environment corresponding to Hyderabad, India to study seasonal and annual distribution of UV-absorbing aerosols. Observations reveal that UV-absorbing aerosol loading is highly seasonal. During the years 1987, 1991 and 1992 high concentration of UV-absorbing aerosols into the atmosphere over Hyderabad region has been observed. UV-absorbing aerosols are high during summer period. Ground-based measurements of aerosol optical depth (AOD) and satellite-derived AI showed good correlation with AOD at .     

AM1 study of structure-activity relationships in bicyclic aza-β-lactams

AM1 calculations on bicyclic aza-β-lactams 4 (1,3-diazetidin-2-ones) are carried out to investigate the effect of ring size (five versus six), position of olefin (Δ² versus Δ³), and electronegative atom (oxygen) in the tethered non-β-lactam ring on the structure of diazetidinone. The results are discussed in terms of structural trends related to β-lactamase and transpeptidase inactivation capability. The biological activity of novel aza-β-lactams 4 is comparable to that of β-lactams3 .     

Objective and subjective evaluation of acoustic comfort in classrooms: A comparative investigation of vernacular and modern school classroom in Kerala

This paper reports a comparative investigation on acoustic comfort of classrooms in vernacular and modern school buildings in tropical warm humid climate. In this type of climate the intrusion of external noise into the classrooms along with cross ventilation is unavoidable. Preliminary investigation on the evaluation of acoustic comfort carried in secondary schools located in Kollam district of Kerala State in India have been reported. As a step ahead, in order to understand the performance of vernacular school classroom in comparison with that of a modern classroom, an initial survey was conducted in classrooms of ten vernacular and 10 modern schools. Further a detail investigation was carried out in a vernacular and modern school building located in the same site. The study was conducted by measuring the two important acoustic parameters viz., background noise and reverberation time which affect the acoustical comfort in the classrooms. The level of satisfaction of the users was evaluated through questionnaires distributed to teachers and students. The result of the scientific analysis was compared to user’s response. The study reveals that modern classrooms are more preferred than vernacular classrooms acoustically, by the teachers and students. The study also confirms a strong need of improving the acoustical comforts in the classrooms.     

Redox-switched oxidation of dihydrogen using a non-innocent ligand

Organometallic complexes containing non-innocent ligands of the type Cp*Ir(tBAFPh)(1), where H2tBAFPh is 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, were found to activate H2 in a redox-switchable manner. The 16e- complex 1 was inert with respect to H2, CO, as well as conventional basic substrates until oxidation. Oxidation of 16-electron 1 with 1 equiv of Ag+ resulted in ligand-centered oxidation affording salts of [1]+, which were characterized by crystallographically, EPR, and elemental analyses. [1]+ was reduced to 1 in the presence of H2 and the sterically hindered base, 2,6-(tBu)2C5H3N, via a pathway that is first-order in both metal and dihydrogen. Compound [1]+ forms adducts with MeCN, which inhibits catalysis. The catalytic oxidation of H2 was established by electrochemical methods to be associated with the monocation.     

Synthesis,XRD, spectral,structural, quantum mechanical and anticancer studies of di(p-chlorobenzyl) (dibromo) (1, 10-phenanthroline) tin (IV) complex

The tin complex di (p-chlorobenzyl) (dibromo) (1, 10-phenanthroline) tin (IV) (4CLBR) was synthesised and subjected to characterization using spectroscopic techniques like FT-IR, Raman, ¹HNMR, ¹³CNMR, ¹¹⁹SnNMR, and crystallography. DFT method was used to compare theoretical and experimental results, and the theoretical method was done by the B3LYP/LanL2DZ. The VEDA programme package was used to design the entire vibrational spectral investigation. The Multiwfn software package was used to calculate the quantum chemical equations. A 2D network (C–H–Cl (C–Cl–H-benzyl, interactions forming a 2D network) and hydrogen bonding formed by bromine atoms such as C–H–Br (Sn–Br–H-Phen) were confirmed by X-rays as the complex and crystallisation. The crystal structure of the complex 4CLBR reveals that the tin atom is in a regular octahedral configuration. At the end of the day, anticancer activity has been investigated in this complex using a variety of cell lines, including PC3 (human prostate cancer cell), MCF7 (breast cancer cell), U937 (blood cancer cell), and U87 (brain cancer cell). The anticancer activity results clearly show that the complex 4CLBR and cisplatin have the same anticancer activity at concentrations of 15.6 g/ml against the U87 cell line.     

Magnetization dynamics of an integrable model of 3D ferromagnetic spin system

We formulate the dynamical equation of a 3 dimensional Heisenberg ferromagnetic (FM) spin system with bilinear and anisotropic interactions in the semiclassical limit. In the continuum limit the dynamics is found to be governed by a (3+1) dimensional nonlinear Schrödinger equation. We check the integrability of the dynamics by constructing Lax pair of operators. To express the nonlinear spin excitations in terms of magnetic soliton, we use Darboux transformation(DT) and Hirota bilinearization procedure .     

Cerium(IV) ammonium nitrate mediated thiocyanation of dienes: Some interesting observations

Various 1,3-dienes when treated with a solution of cerium(IV) ammonium nitrate and ammonium thiocyanate in acetonitrile afforded the isothiocyanatothiocyanates via a [3,3] sigmatropic rearrangement. Electron rich dienes afforded the γ-thiocyanato-α,β-unsaturated carbonyl compounds under similar experimental conditions.     

Resolving the Unpaired‐Electron Orbital Distribution in a Stable Organic Radical by Kondo Resonance Mapping

The adsorption geometry and the electronic structure of a Blatter radical derivative on a gold surface were investigated by a combination of high‐resolution noncontact atomic force microscopy and scanning tunneling microscopy. While the hybridization with the substrate hinders direct access to the molecular states, we show that the unpaired‐electron orbital can be probed with Ångström resolution by mapping the spatial distribution of the Kondo resonance. The Blatter derivative features a peculiar delocalization of the unpaired‐electron orbital over some but not all moieties of the molecule, such that the Kondo signature can be related to the spatial fingerprint of the orbital. We observe a direct correspondence between these two quantities, including a pronounced nodal plane structure. Finally, we demonstrate that the spatial signature of the Kondo resonance also persists upon noncovalent dimerization of molecules.