Some observations on the performance of balloons from the rate of rotation of the fan in the F-Type radiosonde

If the rate of ascent of the balloon is constant, the rate of rotation of the fan in the F-Type radiosonde should decrease with height, due to the decrease in the density of the air. It was observed from the radiosonde ascents of Minicoy that the rate of rotation of the fan remained almost unchanged up to even 100 mb. It is shown that this is due to the increase in the rate of ascent of the balloon by about 2% of the value near the ground per km. ascent. Positive evidence of turbulence in the stratosphere is provided by the large fluctuations in the rate of rotation of the fan. It is also observed that the balloon whose fabric at the 50 mb. level is about 0·014 mm. thick bursts due to the turbulence.     

Analysis of electro-optical and dielectric parameters of TiO2 nanoparticles dispersed nematic liquid crystal

The present investigation is focused on to find out the role of TiO₂ nanoparticles (NPs) on altering the dielectric and electro-optical parameters of nematic liquid crystal (NLC). In addition to this, we also optimized the concentration of dopant (0.25 wt%) for a saturation value of permittivity and dielectric anisotropy in the doped system. Dielectric spectroscopy has been performed with the variation of frequency and temperature to investigate the various dielectric parameters, which demonstrate that the investigated NLC is of positive dielectric anisotropy; the observed result shows a decrement in the value of relative permittivity and dielectric anisotropy; however, the permittivity value increases for higher concentration of dopant but remains less than that of pure NLC. Electro-optical measurements have also been performed to compute the optical response of pure and dispersed NLC. It is found that optical response decreases for the NP-doped systems. This optimized concentration of NPs in NLC matrix can have various credential applications in the field of active matrix display and holography.     

Magnetic-Bottle and Velocity-Map Imaging Photoelectron Spectroscopy of APS- (A=C14H10 or Anthracene): Electron Structure,Spin-Orbit Coupling of APS·, and Dipole-Bound State of APS-

Gaseous dibenzo-7-phosphanorbornadiene P-sulfide anions APS^-(A=C₁₄H₁₀ or anthracene) were generated via electrospray ionization, and characterized by magnetic-bottle photoelectron spectroscopy, velocity-map imaging (VMI) photoelectron spectroscopy, and quantum chemical calculations. The electron affinity (EA) and spin-orbit (SO) splitting of the APS^· radical are determined from the photoelectron spectra and Franck-Condon factor simulations to be EA=(2.62±0.05) eV and SO splitting=(43±7) meV. VMI photoelectron images show strong and sharp peaks near the detachment threshold with an identical electron kinetic energy (eKE) of 17.9 meV at three different detachment wavelengths, which are therefore assigned to autodetachment from dipole-bound anion states. The B3LYP/6-31++G(d, p) calculations indicate APS^· has a dipole moment of 3.31 Debye, large enough to support a dipole-bound electron.     

Synthesis,spectral, DFT,and antimicrobial studies of tin(II) and lead(II) complexes with semicarbazone and thiosemicarbazones derived from (2-hydroxyphenyl)(pyrrolidin-1-yl)methanone

A new series of metal complexes [M(L)₂] (where M = Sn(II), Pb(II), and HL = semicarbazone, thiosemicarbazone or phenylthiosemicarbazone) have been prepared and characterized by elemental analysis, conductance measurements, molecular weight determinations, UV–visible, infrared, and nuclear magnetic resonance (¹H-, ¹³C-, and ¹¹⁹Sn-NMR) spectral studies. Elemental analysis of the metal complexes suggested 1 : 2 (metal–ligand) stoichiometry. Infrared spectra of the complexes agree with coordination to the metal through the nitrogen of the azomethine (>C=N?) and the oxygen/sulfur of the ketonic/thiolic group. Electronic spectra suggest a distorted tetrahedral geometry for all Schiff base complexes. The bond lengths, bond angles, highest occupied molecular orbital, lowest unoccupied molecular orbital, Mulliken atomic charges, and the lowest energy model structure of the complexes have been determined with DFT calculations. Representative Schiff base and its metal chelates have been screened for their in vitro antibacterial activity against four bacteria, Gram-positive (Bacillus cereus, Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) and four strains of fungus (Penicillium chrysogenum, Aspergillus niger, Rhizopus nigricans, and Alternaria alternata). The metal chelates possess higher antimicrobial activity than the free ligands.     

Fluorescent Carbon Quantum Dots Functionalized by Poly L-Lysine: Efficient Material for Antibacterial,Bioimaging and Antiangiogenesis Applications

Journal of Fluorescence - This study illustrates the synthesis of functionalized carbon quantum dots (CQDs) by the one-pot pyrolysis method. The functionalization agent used in CQD synthesis was...     

A simple molecular theory of a nematic–nematic phase transition in highly polar compounds

Abstract

We have extended an earlier molecular model which was developed to explain the double reentrant sequence in highly polar compounds to predict the possibility of a nematic (N₁)–nematic (N₂) phase transition in such compounds. At moderate densities the dipolar interactions would give rise to an antiparallel near neighbour arrangement of the polar molecules while at higher densities, the dipole–induced dipole and chain–chain dispersion interactions give rise to a parallel configuration. The N₁–N₂ transition corresponds to a jump in the relative concentration of the two species. Using the mean field approximation we have calculated the phase diagram. The weak first order transition disappears above a critical point as a function of an appropriate parameter. We have also calculated the specific heat anomaly around the transition region.     

Synthesis and Preclinical Evaluation of QS-21 Variants Leading to Simplified Vaccine Adjuvants and Mechanistic Probes

QS-21 is a potent immunostimulatory saponin that is currently under clinical investigation as an adjuvant in various vaccines to treat infectious diseases, cancers, and cognitive disorders. Herein, we report the design, synthesis, and preclinical evaluation of simplified QS-21 congeners to define key structural features that are critical for adjuvant activity. Truncation of the linear tetrasaccharide domain revealed that a trisaccharide variant is equipotent to QS-21, while the corresponding disaccharide and monosaccharide congeners are more toxic and less potent, respectively. Modification of the acyl chain domain in the trisaccharide series revealed that a terminal carboxylic acid is well-tolerated while a terminal amine results in reduced adjuvant activity. Acylation of the terminal amine can, in some cases, restore adjuvant activity and enables the synthesis of fluorescently labeled QS-21 variants. Cellular studies with these probes revealed that, contrary to conventional wisdom, the most highly adjuvant active of these fluorescently labeled saponins does not simply associate with the plasma membrane, but rather is internalized by dendritic cells.