Contact charging between surfaces of identical insulating materials in asymmetric geometries

The charging that occurs when a pair of insulating surfaces of identical chemical composition are rubbed (i.e. triboelectric charging) remains poorly understood. It is believed that asymmetry in contact plays an important role in this charging. To study this phenomenon, we have developed an experimental methodology that asymmetrically rubs two surfaces by contacting a rotating cylinder with a stationary cylinder – the rubbing is asymmetric in that the contacting area is much greater on the rotating cylinder than on the stationary cylinder. We find that the charge transfer occurs with a spatial distribution of charge, in terms of magnitude and polarity, on the contacted area. The direction of the average charge transfer is material dependent: for Teflon–Teflon contact, the surface with the larger contacting area charges positively, but for Nylon–Nylon contact the surface with the larger contacting area charges negatively. This difference is interpreted as being due to a negatively-charged species transferred in the case of Teflon (electrons or negative ions), but a positively-charged species transferred in the case of Nylon (positive ions).     

Studies on Substituted Derivatives of Polyaniline: Effect of Polymerization Conditions on Electrical Conductivity

Abstract

Polyaniline, poly(o-methoxyaniline)and poly(N-phenylaniline) were synthesized chemically under different polymerization conditions by peroxodisulphate oxidation in HCl and in a mixture of HCl and CH₃CN. The polymer prepared at 0°C, monomer-oxidant ratio 1:1.15 and a strong acidic medium, has the least bandgap and maximum electrical conductivity. The electrical conductivity depends on degree of oxidation and protonation. The bulky substituents increase the torsion angle and hence disorder causes the decrease in the electrical conductivity of polymer.     

Visible light active anion codoped sol gel titania photocatalyst for pollutant degradation

The photocatalytic activity of carbon and nitrogen co-doped sol gel TiO₂ is tested using methyleneblue degradation and it is found that the activity drops sharply with increase in calcination temperature. The system calcined at 300 °C was found to be the most efficient in dye degradation and can be considered as a good candidate for the future photocatalytic applications. This highly active anion doped TiO₂ is found to show amorphous nature. Elemental analysis reveals the co existence of C and N dopants, which may be responsible for the high efficiency of the catalyst. Visible absorbance is evident from the UV–VIS Diffuse Reflectance Spectra. The N₂ adsorption desorption studies show the H1 hysteresis loops and a well defined mesoporous nature is observed for the catalytic systems prepared in the presence of urea. XPS analysis indicates the presence of Ti–C and Ti–N bonds which are responsible for the visible light activity of the photocatalysts.     

Embeddings of Hyperbolic Kac–Moody Algebras into E 10

We show that the rank 10 hyperbolic Kac–Moody algebra E ₁₀ contains every simply laced hyperbolic Kac–Moody algebra as a Lie subalgebra. Our method is based on an extension of earlier work of Feingold and Nicolai.      

Dolbeault cohomology of compact complex homogeneous manifolds

We show that ifM is the total space of a holomorphic bundle with base space a simply connected homogeneous projective variety and fibre and structure group a compact complex torus, then the identity component of the automorphism group ofM acts trivially on the Dolbeault cohomology ofM. We consider a class of compact complex homogeneous spacesW, which we call generalized Hopf manifolds, which are diffeomorphic to S¹ ×K/L whereK is a compact connected simple Lie group andL is the semisimple part of the centralizer of a one dimensional torus inK. We compute the Dolbeault cohomology ofW. We compute the Picard group of any generalized Hopf manifold and show that every line bundle over a generalized Hopf manifold arises from a representation of its fundamental group.     

Analytical method development and validation for the simultaneous estimation of quercetin,berberine, rutin and curcumin in a polyherbal formulation using high-performance thin-layer chromatography

JPC – Journal of Planar Chromatography – Modern TLC - People all over the world are affected by the chronic, disabling autoimmune illness known as rheumatoid arthritis (RA). Herbal...