Visible Colorimetric Sensor for Fluoride Ion Based on o-Phenylenediamine

A new chromogenic receptor based on 1,2-phenylene derivative containing thiourea moieties is synthesized and examined for its anion binding ability by UV–Vis and ¹H NMR studies. The results show that the receptor has selective colorimetric sensing of fluoride over all other anions like chloride, bromide, iodide, nitrate, hydrogen sulphate and acetate.     

Intraspecific competition of predator for prey with variable rates in protected areas

Nonlinear Dynamics - In this present study, we systematically explore the periodicity (almost periodic nature) of a dynamical system in time-varying environment, which portrays a special case of...     

Development of Humidity Sensor Using Nanoporous Polycarbonate Membranes

Russian Journal of Physical Chemistry A - In the present work, the effect of temperature and moisture has been studied on nano-porous polycarbonate membranes of size 15, 50, and 80 nm, respectively...     

Angular momentum and cross sections for fusion with weakly bound nuclei: breakup,a coherent effect

Results for the cross section and average angular momentum for complete fusion at energies around the Coulomb barrier are presented for 7Li with 165Ho. Comparison of the cross sections with a one-dimensional barrier penetration model, using a potential consistent with the measured elastic scattering, showed a reduction above the barrier and an enhancement below it. An increase in the measured average angular momentum, , above the barrier and its consistency with that obtained from the fusion excitation function for weakly bound nuclei, is reported. These results together with a reanalysis of existing data conclusively demonstrate that the effect of breakup on fusion is coherent, like coupling to any nonelastic channel.     

Synthesis and characterization of functional polysilanes [RMe2Si(CH2)x(Me)Si]n (R = 2‐Fu, 5‐Me‐2‐Fu, 2‐Th, 4‐Me‐2‐Th; x = 2, 3) with appended furyl/thienyl groups on the carbosilyl side chains and their application in the generation and stabilization of palladium nanoparticles

The polysilanes [RMe₂Si(CH₂)_x(Me)Si]_n [x = 2, 3; R = 2‐Fu ( 1, 2 ), 5‐Me‐2‐Fu ( 3, 4 )] bearing furyl‐substituted carbosilyl side chains have been synthesized by dehalocondensation reaction (Wurtz coupling) of the corresponding carbosilanes using sodium dispersion in refluxing toluene. On the other hand, analogous polysilanes with appended thienyl groups [x = 2, 3; R = 2‐Th ( 5, 6 ), 4‐Me‐2‐Th ( 7, 8 )] are only accessible by the reaction of the corresponding carbosilane precursors under mild Wurtz coupling conditions (THF, RT). These polysilanes reveal monomodal molecular weight distribution with M_w/PDI = 3.3–5.4 × 10⁴/1.22–1.47 ( 1–4 ) and 9.1–14.4 × 10⁴/1.45–1.61 ( 5–8 ) and are characterized by FT‐IR, multinuclear (¹H, ¹³C{¹H}, ²⁹Si{¹H}) NMR, and UV/PL spectral studies as well as thermogravimetric analysis (TGA). Preliminary studies on the reactivity of polysilane 2 with palladium acetate (toluene, RT) reveal the formation of spherical palladium nanoparticles of size 8.2 ± 0.6 nm, which remain stable in solution for several weeks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7816–7826, 2008     

Validated HPTLC method for quantitative determination of gallic acid in stem bark of Myrica esculenta Buch.-Ham. ex D. Don, myricaceae

A simple, rapid, and precise HPTLC method was developed for quantitative estimation of gallic acid in stem bark of Myrica esculenta, family Myricaceae. Separation was performed on silica gel 60F254 HPTLC plates using toluene-ethyl acetate-formic acid-methanol (3 + 3 + 0.6 + 0.4, v/v/v/v) mobile phase for separation of the extracted components. The determination was carried out in the UV densitometric absorbance-reflection mode at 280 nm. The amount of gallic acid in free and combined form in the stem bark powder was found to be 0.276 and 0.541%, respectively, on a dry weight basis. The method was validated in terms of linearity, accuracy, precision, and specificity according to International Conference on Harmonization guidelines. Gallic acid response was found to be linear over a broad concentration range of 0.4-2.0 microg/band. LOD and LOQ were 0.103 and 0.312 microg/spot, respectively. The developed method is capable of quantifying amounts of gallic acid in stem bark powder of M. esculenta.     

Validated HPTLC Method for Quantification of Myricetin in the Stem Bark of Myrica esculenta Buch. Ham. Ex D. Don,Myricaceae

JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid, and precise high-performance thin-layer chromatographic method has been established for quantitative analysis of...     

On the limitations of the equation of state based on the Lennard-Jones potential

It is emphasized that any equation of state (EOS) based on the generalized Lennard-Jones potential or the Mie potential, suffers from two main shortcomings as pointed out by Stacey and Davis [2]. One of the shortcomings viz. the problem related to imaginary numbers for the exponents in the potential function, has been removed recently by Jiuxun [11] by using a relationship between the exponents. However, the modified EOS obtained by Jiuxun suffers from the second shortcoming viz. it gives lower values for −B ₀ B″₀, an important equation of state parameter related to the second pressure derivative of the bulk modulus. Values of B ₀ B″₀ obtained by Jiuxun are not consistent with those reported by Stacey and Davis.      

Thiacalix[4]arene based reconfigurable molecular switches: set-reset memorized sequential device

The fluorescent chemosensors 3, 5 and 7 based on thiacalix[4]arene bearing naphthyl groups have been designed and synthesized. The optical chemosensor 3 based on a thiacalix[4]arene of cone conformation behaves as "turn-on" optical chemosensor for Fe(3+) and F(-) ions. However, chemosensors 5 and 7 based on a thiacalix[4]arene of 1,3-alternate conformation demonstrate "turn-on" optical behaviour for Hg(2+), F(-) ions (with receptor 5 as turn-on for K(+) ions also) and "turn-off" behaviour for Fe(3+) ions. The simultaneous presence of Fe(3+) and Hg(2+) or K(+) or F(-) ions results in formulation of reversible "on-off" switches. Various molecular logic gates developed in response to molecular switching between these chemical inputs have been integrated into sequential logic circuits with memory function in a feedback loop which mimics "set-reset" molecular level information processing device.