Innovative synthesis of citrate-coated superparamagnetic Fe3O4 nanoparticles and its preliminary applications

In this study, we describe the development of a facile and effective route for the synthesis of Fe(3)O(4)-based T(1) contrast agent, which can be useful for in vivo magnetic resonance (MR) imaging. Citrate-coated Fe(3)O(4) nanoparticles (6 nm) with a narrow size distribution were synthesized by "one-pot green chemistry route" in diethylene glycol (DEG) solvent. The synthesized nanoparticles were characterized by different analytical techniques including XRD, TEM, HRTEM, and FTIR. At room temperature, nanoparticles exhibited superparamagnetic nature with high saturation magnetization. The longitudinal (r(1)) and transverse (r(2)) relaxivities were found to be 35.45 and 51.81 mM(-1)s(-1), respectively. Contrast agent developed by this method showed a relatively higher longitudinal relaxivity (r(1)) and the lowest relaxivity ratio (r(2)/r(1)=1.46) at 3T MR field. The anionic nature of citric acid facilitated non-specific internalization without impairment of cell viability and functionality. The in vitro studies showed both phagocitic and non-phagocytic uptake of these NPs. In vivo MR imaging of swine showed both T(1) and T(2) contrast effect.     

Isolation and characterization of degradation products of moxidectin using LC, LTQ FT-MS, H/D exchange and NMR

This study aimed to evaluate the degradation profile and pathways, and identify unknown impurities of moxidectin under stress conditions. During the experiments, moxidectin samples were stressed using acid, alkali, heat and oxidation, and chromatographic profiles were compared with known impurities given in European Pharmacopeia (EP) monograph. Moxidectin has shown good stability under heat, while reaction with alkali produced 2-epi and ?2,3 isomers (impurities D and E in EP) by characteristic reactions of the oxahydrindene (hexahydrobenzofuran) portion of the macrocyclic lactone. Two new, previously unreported, unknown degradation products, i.e. impurity 1 and impurity 2, detected after acid hydrolysis of moxidectin (impurity 2 was also observed to a lesser extent after oxidation), were isolated from sample matrices and identified using liquid chromatography, NMR, high-resolution FT-ICR MS, and hydrogen/deuterium exchange studies. FTMS analysis showed accurate mass of molecular ion peaks for moxidectin at m/z 640.38412, impurity 1 at m/z 656.37952 and impurity 2 at m/z 611.35684, giving rise to daughter ions traceable up to the seventh levels of MSⁿ experiments and supporting the proposed structures. Both unknown impurities along with moxidectin were fully characterized by ¹H, ¹³C, 1D HMBC and 2D (NOESY, COSY and HSQC) NMR experiments. The interpretation of experimental data positively identified impurity 1 as 3,4-epoxy-moxidectin and impurity 2 as 23-keto-nemadectin. The identification of new impurities and correlation of their chromatographic profiles with the EP method is very useful to establish the stability profile of moxidectin and its preparations, as well as add value to the forthcoming moxidectin finished product European Pharmacopeia monographs.

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

We observe that light soaking for short durations and thermal quenching in nanocrystalline porous silicon (PS) produce metastable states. These metastable states show higher dark and photo currents, large photoluminescence and a weaker electron spin resonance (ESR) signal. However, long exposures to light produce the opposite effect. The metastable states are stable against sub-band gap light exposures. These metastable states can be removed by annealing at 150°C for 1 h. ESR shows the presence of a-Si phase (g ～ 2.0058, 6.4 G) in PS sample, but it is not sufficient to explain all the experimental results. Rather, our experiments suggest that light soaking causes more than one type of defects in porous silicon. The structural changes involving the movement of hydrogen present at the surface of PS or at the PS/a-Si interface may be responsible for these effects.     

Molecular Force Fields of XY6 Type Molecules

Octahedral molecules of XY₆ type belonging to O_h symmetry have six normal modes of vibrations. On group theoretical considerations, Λ_vib, = a^1g + e_g + 2t_1u + t_2g + t_2u     

Ultrasonic attenuation in copper at low temperatures

Ultrasonic attenuation in copper at low temperatures has been analysed in terms of electron-electron and electron-phonon interactions. The contribution due to electron-electron interactions has been evaluated using a simplified spherical Fermi-surface model with an isotropic Umklapp transition probability. We observe that the contribution to the attenuation constant (α) due to electron-electron scattering in copper at 3 K is about 10% of the electron-phonon contribution. We have also considered the viscous attenuation and the induction attenuation mechanisms simultaneously in copper as suggested by Orlov and find that our results improve the existing theoretical data considerably.     

RLIP76, a non-ABC transporter,and drug resistance in epilepsy

Background  

Permeability of the blood-brain barrier is one of the factors determining the bioavailability of therapeutic drugs and resistance to chemically different antiepileptic drugs is a consequence of decreased intracerebral accumulation. The ABC transporters, particularly P-glycoprotein, are known to play a role in antiepileptic drug extrusion, but are not by themselves sufficient to fully explain the phenomenon of drug-resistant epilepsy. Proteomic analyses of membrane protein differentially expressed in epileptic foci brain tissue revealed the frequently increased expression of RLIP76/RALBP1, a recently described non-ABC multi-specific transporter. Because of a significant overlap in substrates between P-glycoprotein and RLIP76, present studies were carried out to determine the potential role of RLIP76 in AED transport in the brain.     

Microwave-mediated solvent free Rap-Stoermer reaction for efficient synthesis of benzofurans

The Rap-Stoermer reaction of salicylaldehydes with diverse phenacyl bromide and phenacyl iodides proceeded cleanly to afford various functionalized benzofurans in excellent yields under base-mediated solvent free microwave irradiation conditions.     

Partially carbonized tungsten oxide as electrode material for asymmetric supercapacitors

Journal of Solid State Electrochemistry - Synthesis of partially carbonized tungsten oxide employing a simple, one-step, and scalable in-situ reduction/carbonization process is reported along with...