Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20microg mL(-1) (r2=0.9999) in deionised water and 1-24 microg mL(-1) (r2=0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 x 10(3)L mol(-1)cm(-1) and 0.0422 microg cm(-2)/0.001A in deionised water; and 3.05 x 10(3)L mol(-1)cm(-1) and 0.0567 microg cm(-2)/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 microg mL(-1) in deionised water and 0.13 and 0.40 microg mL(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.     

Nature of quantum recurrences in coupled higher dimensional systems

We investigate recurrence phenomena in coupled two degrees of freedom systems. It is shown that an initial well localized wave packet displays recurrences even in the presence of coupling in these systems. We discuss the interdependence of time scales namely classical period and quantum revival time and explain the significance of initial conditions.     

Nuclear surface waves in alpha-particle and ion-ion collisions

Our earlier methods of interpretation of the resonances in ion-ion scattering (such as ¹²C + ¹²C, ¹²C + ¹⁶O, or ¹⁶O + ¹⁶O where they appear both experimentally and via optical-model calculations) in terms of nuclear surface waves are applied to the case of α-⁴⁰Ca scattering. The optical-model resonance results of Brink et al. are here extended in order to render them suitable for a surface-wave picture as well. Recent experimental results on ¹²C + ¹²C scattering are used to demonstrate the existence of surface waves of both Rayleigh and whispering gallery type in this system.     

Improvement in energy conversion of electrostrictive composite materials by new approach via piezoelectric effect: Modeling and experiments

This study proposes a new model that couples the piezoelectric and electrostrictive behavior to minimize the polarization power of composite polymer. The development of this model is capable to predict the energy harvesting abilities of an electrostrictive composite. To improve the dielectric permittivity of electrostrictive polymer, the particles of PZT have been incorporated in order to increase the conversion efficiency of the composite. Dielectric characterization tests showed an increase in dielectric permittivity by a factor of 4.5 compared to pure polymer. Experimental measurements of harvested power validate the analytical model and demonstrate a good correlation between the two data. An equivalent of an electrical scheme has been developed, which allows modeling the two behaviors. The harvested power density under low frequency at 2% of strain can reach 0.30 μW/cm³ for 33% of PZT without the polarization field, including the conversion efficiency becomes higher. The energy harvester property of this material composite has excellent potential for several self‐powered applications such as wireless sensor networks and the internet of things.     

Application of validated RP-HPLC method for simultaneous determination of docetaxel and ketoconazole in solid lipid nanoparticles

Docetaxel has significant single agent activity in prostate cancer and ketoconazole also has activity as a second line hormonal agent. In vitro, ketoconazole is synergistic with some chemotherapy agents by enhancing the intracellular retention of the cytotoxic agent. A potential drug-drug interaction exists though between docetaxel and ketoconazole because both agents are metabolized hepatically by the cytochrome P-450 system. Hence, a nanoparticulate system was formulated by loading both drugs for tumor targeting. Assay and in vitro release of the formulation were conducted by developing simple, precise, accurate, and validated analytical method for simultaneous determination docetaxel and ketoconazole using reversed-phase high-performance liquid chromatography (RP-HPLC). The RP-HPLC method was developed using Waters Symmetry C(18) column (25 cm × 4.5 mm, 5 μm) with a mobile phase consisting of acetonitrile and 0.2% triethylamine pH adjusted to 6.4 (48:52, v/v) at flow rate of 1 mL/min. Intra-day and inter-day variations were less than 2% over the linearity range, 0.5-20 μg/mL. The proposed two methods were successfully applied for the determination of docetaxel and ketoconazole in solid lipid nanoparticles.     

Gene-Z: a device for point of care genetic testing using a smartphone

By 2012, point of care (POC) testing will constitute roughly one third of the $59 billion in vitro diagnostics market. The ability to carry out multiplexed genetic testing and wireless connectivity are emerging as key attributes of future POC devices. In this study, an inexpensive, user-friendly and compact device (termed Gene-Z) is presented for rapid quantitative detection of multiple genetic markers with high sensitivity and specificity. Using a disposable valve-less polymer microfluidic chip containing four arrays of 15 reaction wells each with dehydrated primers for isothermal amplification, the Gene-Z enables simultaneous analysis of four samples, each for multiple genetic markers in parallel, requiring only a single pipetting step per sample for dispensing. To drastically reduce the cost and size of the real-time detector necessary for quantification, loop-mediated isothermal amplification (LAMP) was performed with a high concentration of SYTO-81, a non-inhibiting fluorescent DNA binding dye. The Gene-Z is operated using an iPod Touch, which also receives data and carries out automated analysis and reporting via a WiFi interface. This study presents data pertaining to performance of the device including sensitivity and reproducibility using genomic DNA from Escherichia coli and Staphylococcus aureus. Overall, the Gene-Z represents a significant step toward truly inexpensive and compact tools for POC genetic testing.     

Comment on ‘Generalized Heisenberg algebra coherent states for power-law potentials’ [Phys. Lett. A 375 (3) (2011) 298]

We argue that the statistical features of generalized coherent states for power-law potentials based on Heisenberg algebra, presented in a recent paper by Berrada et al. (2011) [1] are incorrect.     

Isotope separation via atom optics in the Bragg regime

We study the resonant interaction of a beam of mono-velocity two-level atoms with a standing-wave light field in the Bragg regime. The atomic beam consists of two different isotopes, and the density is sufficiently small so that at most one atom is inside the cavity at a time. The momentum transfer between the atoms and photons in the process significantly effects the center-of-mass motion of the atoms, thus separating the isotopes in different directions.     

Recurrence Tracking Microscope: Nanoscanning Via Bose–Einstein Condensation

A recurrence tracking microscope works on quantum recurrence phenomena of the wave packet and probes nanostructures on a surface. The important advantage of condensed atoms over cold atoms is the very small distribution size due to the atom–atom interactions. We report a more precise measurement of the quantum revival time. For small nonlinear interatomic interactions, there is a small change in quantum revival times; however, as the interaction becomes stronger, we find visible changes in the revival time. The change in the initial height of the nanoparticles is due to the variation in the revival times at different positions of the cantilever.     

Determination of lead in tooth-pastes by electrothermal atomic-absorption spectrophotometry with platform atomization

Electrothermal atomic-absorption spectrometry is used for the determination of lead in tooth-pastes, by means of the graphite platform/matrix-modification technique. The method is easy to apply, has limited interferences and is more precise than conventional flame AAS. The working concentration range is up to 100 mug/1. The method is characterized by a detection limit of 0.08 mug/1. and a precision of +/-1.9 % for the sample solutions. For the tooth-pastes, the detection limit is between 1.1 and 5.4 ng/g and the precision in the range 1.8-10%.