Low frequency Raman scattering from acoustic phonons confined in ZnO nanoparticles

We report here the first observation of the low frequency Raman scattering from acoustic phonons in semiconducting zinc oxide (ZnO) nanoparticles without embedding in any solid matrix. ZnO nanoparticles (size 5-10 nm) with nearly spherical shape have been synthesized using a chemical route. A shift in the phonon peaks toward higher frequencies along with broadening was observed with a decrease in particle size. The size dependence of the acoustic phonons in ZnO nanoparticles is explained using Lamb's theory that predicts the vibrational frequencies of a homogeneous elastic body of spherical shape. Our results show that the observed low frequency Raman scattering originates from the spherical (l = 0) and quadrupolar vibrations (l = 2) of the spheroidal mode due to the confinement of acoustic vibrations in ZnO nanoparticles.     

Bioimaging of Peroxynitrite in MCF-7 Cells by a New Fluorescent Probe Rhodamine B Phenyl Hydrazide

Peroxynitrite is a potent oxidizing and nitrating agent which has detrimental effects on cells by altering the structure and function of biomolecules present within. A fluorescent probe rhodamine B phenyl hydrazide (RBPH) has been proposed for peroxynitrite (ONOO^?) imaging in MCF-7 cells based on its oxidation property, which converts RBPH to pink colored and highly fluorescent rhodamine B. The fluorescence emission intensity of the rhodamine B produced in the above process is linearly related to the concentration of peroxynitrite. The method obeys Beer’s law in the concentration range 2–20 nM and the detection limit has been found to be 1.4 nM. The possible reaction mechanism of peroxynitrite with RBPH to produce rhodamine B has been discussed with spectroscopic evidence. The Probe is selective to the peroxynitrite in the pH range 6–8 which is near physiological pH. Fluorescence microscopic studies suggest that the probe is cell permeable and hence peroxynitrite was imaged in MCF-7 cells.     

Design and synthesis of two armed molecular receptor for recognition of Gd3+ metal ion and its computational study

New receptor P henylene‐ B is‐ M ethylfuran‐yl‐2‐ M ethyele A cetohydrazide ( PBMMA ) has been synthesized by condensation of hydrazide and 5‐methyl furfural. Synthesized receptor has been fully characterized by IR, ¹H NMR, ¹³C NMR, mass spectroscopic and thermo gravimetric analysis. The receptor PBMMA shows selective recognition potential towards Gd³⁺ ion when tested with several metal ions such as Na⁺, K⁺, Mg²⁺, Cu²⁺, Cd²⁺, Hg²⁺, Y³⁺, La³⁺, Eu³⁺, Sm³⁺, Gd³⁺, Re⁶⁺ and Th⁴⁺ ion as their sulfates by UV–visible and fluorescence spectroscopic studies. Binding nature of PBMMA with Gd³⁺ ion was further studied by mass spectroscopic and cyclic voltammetric studies. The stoichiometry of PBMMA‐ Gd³⁺ ion has been established, 1:1 by Benesi‐Hildebrand plot method and method of continuous variation (Job's plot) with association affinity K = 6.491 × 10⁴ M^?1. In addition to these, molecular docking, molecular dynamic stimulation and binding energy of complex; through Density Function theory ?595.66 kcal/mol has also indication of strong binding. The electron transfer energy of Higher occupied molecular orbital (HOMO) to Lower unoccupied molecular orbital (LUMO) is about 4.186 eV and 295 nm for PBMMA‐Gd³⁺ Complex.     

LC–MS Determination of Gabapentin from Human Plasma

Gabapentin is an anticonvulsant drug used for the treatment of epilepsy. It is not bound to plasma protein and is not metabolized. A high performance liquid chromatography–mass spectrometric micro method is described in this report for its determination from human plasma. Chromatography was performed on a 50 × 4.6 mm, 4 μm nitrile column and the parent ion detected in the positive ionization mode on single quadrupole analyzer (Q1MI) with atmospheric pressure ionization source. Extraction was carried out on C₁₈, 100 mg/3cc cartridge using 10 μL sample volume. The mean extraction recovery was 97% and within batch and between batch coefficients of variation were <9%. Lack of interference from endogenous substances helped in achieving a highly sensitive method without the need for monitoring fragment ions. The lowest concentration injected on column for calibration curve was 195 pg (range 0.5–64 ng). The method was applied for analysis of samples from a cross-over bio-equivalence study comparing two formulations.

     

Synthesis and Electrochemical Investigation of Tetra Amino Cobalt (II) Phthalocyanine Functionalized Polyaniline Nanofiber for the Selective Detection of Dopamine

A new electrochemical sensing platform based on tetra‐amino cobalt (II) phthalocyanine (TACoPc) ingrained polyaniline (PANI) nanofiber composite (TACoPc/PANI hybrid) has been developed for the selective detection of dopamine. The uniform fibrous network of PANI/TACoPc hybrid was synthesized by a one‐step oxidative polymerization at room temperature. The synthesized nanocomposite was characterized using field emission scanning electron microscopy (FESEM), energy dispersive X‐ray (EDX), fourier transmission infrared spectroscopy (FTIR), raman spectroscopy, X‐ray diffraction (XRD) and UV‐Visible spectroscopy. The electrochemical behavior of the TACoPc/PANI hybrid material was studied by using different electrochemical techniques, including cyclic voltammetry (CV) and chronoamperometry in 0.1 M phosphate buffer solution (PBS) of pH 7 by modifying the glassy carbon electrode (GCE). Due to the synergistic impact of PANI and TACoPc, the suggested altered electrode provided superior catalytic performance for dopamine even in the presence of ascorbic acid. It exhibited a linear reaction with a high sensitivity of 1.212 μA/μM cm^?2 and a low detection limit of 0.064 μM over the 20–200 μM concentration range in 0.1 M PBS. One of the commonly faced problems of interference of ascorbic acid and uric acid in the electrochemical detection of dopamine was completely excluded from this modified electrode which led to an increase in the catalytic activity of the material for the detection of dopamine in the presence of ascorbic acid.     

高效液相色谱－荧光检测法测定人血浆中匹伐他汀的含量

 Pitavastatin belongs to the class of coenzyme A reductase inhibitors. Very few methods of assaying pitavastatin from human plasma are available in literature. An analytical method is presented for the determination of the drug from human plasma making use of the fluorescent property of the drug. The drug is extracted from plasma using ethyl acetate under neutral condition and then analyzed by reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection (λEx 245 nm; λEm 420 nm). Analysis of pitavastatin was carried out on a C18 HPLC column using a gradient flow of mobile phase (0.01 mol/L monobasic potassium phosphate (pH 3.20)-acetonitrile, 63∶37, v/v). Fluorescein isothiocyanate was used as internal standard. The dynamic range of assay was 3 to 50 ng/mL. The intraday precision was less than 10% and accuracy ranged from 95.2% to 112.6%. The same for interday check was less than 12% and 92.8% to 105.1%, respectively. The drug was found to be stable under the assay conditions. The developed method is simple, precise, accurate, and stable. This indicates that it can be applied to routine analysis of this drug in human subjects where there are large numbers of samples without the need of specialized instruments like column switching.     

Weyl curvature and the Euler characteristic in dimension four

We give lower bounds, in terms of the Euler characteristic, for the L²-norm of the Weyl curvature of closed Riemannian 4-manifolds. The same bounds were obtained by Gursky, in the case of positive scalar curvature metrics.     

Radiation-induced modifications of point defects in quartz crystals and their application in radiation dosimetry

Different types of impurity-related point defects in crystalline quartz are known to exhibit various spectroscopic signals. When exposed to ionizing radiations, these defect centers get modified and new species of point defects are formed. This paper presents a study and discussion of radiation-induced modification of point defects in natural as well as cultured quartz, with an emphasis to use this material for radiation dosimetry up to a range of a few Mrad.     

Synthesis and Characterization of New Helical Coumarins

The phenomenon of peri interaction of 1,8‐disubstituted naphthalene has been utilized to construct small molecules with internal twist resulting in helical isomers. A series of new naphthalene‐attached coumarins have been synthesized and characterized. The helical conformational twist in thiophene–coumarin capped naphthalene was established by H‐NMR and single crystal X‐ray diffraction analysis.