Study on the Fluorescence Quenching Reaction of Amitriptyline and Clomipramine Hydrochlorides with Eosin Y and its Analytical Application

Amitriptyline.HCl (AMI) and clomipramine.HCl (CMI) react with eosin Y (EY) in pH 3.8 NaAc-AcH buffer solution to form ion association complex which results in quenching of fluorescence of EY and appearance of a new resonance Rayleigh scattering (RSS) spectrum at 620 nm. The spectral characteristics of absorption, fluorescence and RSS spectra have been investigated. The factors influencing the reaction were studied and optimum conditions for the reaction have been determined. Based on fluorescence quenching, a simple and sensitive spectrofluorimetric method for determination of AMI and CMI has been developed. The fluorescence quenching intensity was measured at 550 nm using an excitation wavelength of 310 nm. The calibration graph was found to be rectilinear in the range 0.08–2.0 μg?mL^?1 with detection limit of 0.017 μg?mL^?1 for AMI and 0.06–2.0 μg?mL^?1 with detection limit of 0.015 μg?mL^?1 for CMI. The method can be satisfactorily applied to the determination of AMI and CMI in tablets without interference from commonly occurring exicipients. The recovery and RSD values obtained indicate good accuracy and precision of the method. The mechanism of the reaction and fluorescence quenching has also been discussed.     

On a class of prime entire functions

In this note it is proved that entire functions of the form Fa（z）=H（z）-aα（z）
where H andα are entire functions, with α having at least one zero, H＇ and α＇having no common zeros and T（r, α） = S（r, H）, are prime in entire sense for most values of a. The class of these functions is seen to contain examples of both periodic and non-periodic prime entire functions found by Noda, Qiao, Urabe and by Singh and Charak. Another result due to Singh and Charak will be improved as well.     

Diffusion of Au in amorphous Zr x Ni100−x alloys studied by Rutherford Backscattering Spectrometry

The diffusion coefficients (D) of Au in three binary amorphous Zr _x Ni_100–x (x=61, 65, and 67) alloys were measured in the temperature range 549–623 K using the technique of the Rutherford Backscattering Spectrometry (RBS). The D values were found to lie in the range 1.0×10^–21–9.0×10^–20 m²s^–1 for different alloys. The activation energy (Q) was calculated in each case on the basis of an observed Arrhenius temperature dependence of D. The activation energy was found to scale with the crystallization temperature (T _x) of the alloy. Other published measurements for Au diffusion in amorphous Zr-Ni alloys also appear to follow the scaling relation between Q and T _x.     

P(i-PrNCH2CH2)3N: an efficient catalyst for TMS-1,3-dithiane addition to aldehydes

Herein we report the use of commercially available P(i-PrNCH₂CH₂)₃N (1a) as an efficient catalyst for 2-trimethylsilyl-1,3-dithiane (TMS-dithiane) addition to aldehydes at room temperature. The catalyst loading required for these reactions (5 mol %) is the lowest recorded in the literature, and the majority of the reaction times for this transformation are the shortest thus far reported. A variety of functional groups are tolerated on the aryl aldehyde substrates.     

A validated LC‐MS/MS assay for simultaneous quantification of methotrexate and tofacitinib in rat plasma: application to a pharmacokinetic study

A highly sensitive, specific and rapid LC‐ESI‐MS/MS method has been developed and validated for simultaneous quantification of methotrexate (MTX) and tofacitinib (TFB) in rat plasma (50 μL) using phenacetin as an internal standard (IS), as per the US Food and Drug Administration guidelines. After a solid‐phase extraction procedure, the separation of the analytes and IS was performed on a Chromolith RP_18e column using an isocratic mobile phase of 5 m m ammonium acetate (pH 5.0) and acetonitrile at a ratio of 25:75 (v/v) using flow‐gradient with a total run time of 3.5 min. The detection was performed in multiple reaction monitoring mode, using the transitions of m/z 455.2 → 308.3, m/z 313.2 → 149.2 and m/z 180.3 → 110.2 for MTX, TFB and IS, respectively. The calibration curves were linear over the range of 0.49–91.0 and 0.40–74.4 ng/mL for MTX and TFB, respectively. The intra‐ and interday accuracy and precision values for MTX and TFB were <15% at low quality control (QC), medium QC and high QC and <20% at lower limit of quantification. The validated assay was applied to derive the pharmacokinetic parameters for MTX and TFB post‐dosing of MTX and TFB orally and intravenously to rats. Copyright © 2014 John Wiley & Sons, Ltd.     

Image enhancement via Median-Mean Based Sub-Image-Clipped Histogram Equalization

This paper presents a robust contrast enhancement algorithm based on histogram equalization methods named Median-Mean Based Sub-Image-Clipped Histogram Equalization (MMSICHE). The proposed algorithm undergoes three steps: (i) The Median and Mean brightness values of the image are calculated. (ii) The histogram is clipped using a plateau limit set as the median of the occupied intensity. (iii) The clipped histogram is first bisected based on median intensity then further divided into four sub images based on individual mean intensity, subsequently performing histogram equalization for each sub image. This method achieves multi objective of preserving brightness as well as image information content (entropy) along with control over enhancement rate, which in turn suits for consumer electronics applications. This method avoids excessive enhancement and produces images with natural enhancement. The simulation results show that MMSICHE method outperforms other HE methods in terms of various image quality measures, i.e. average luminance, average information content (entropy), absolute mean brightness error (AMBE) and background gray level.     

“On-water” synthesis of 3-substituted indoles via Knoevenagel/Michael addition sequence catalyzed by Cu doped ZnS NPs

Cu doped ZnS NPs represent a green catalyst for an ‘on-water’ one-pot rapid synthesis of 3-substituted indole derivatives via Knoevenagel/Michael addition reaction of indane-1,3-dione, aromatic aldehydes, and indole. The catalytic activity of Cu doped ZnS NPs was about sevenfold higher as compared to the ZnS NPs. The Cu doped ZnS NPs catalyst could be recovered and reused for five reaction cycles, giving a total TOF = 201 h⁻¹.