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.     

(NH4)2Ce(NO3)6 as an inexpensive,eco-friendly,efficient catalyst for the synthesis of 5-substituted 1-H tetrazoles from nitriles

Ceric ammonium nitrate (CAN) is found to be a suitable, inexpensive, and effective non-toxic catalyst for a smooth (3+2) cycloaddition of organic nitriles with NaN₃ to afford 5-substituted 1H-tetrazoles in excellent yields. Shorter reaction times, easy work-up, and substantial and pure product formation are the key advantages of the present method.     

A route to functionalized pyrimidines from carbohydrates via amine-driven dehydrative ring transformations

A novel and expeditious synthetic protocol for functionalized pyrimidines using unprotected aldoses as biorenewable resources is reported. The synthesis involves aza-Michael addition of aromatic amines to aldose-derived 1,3-oxazin-2-ones(thiones) followed by dehydrative ring transformation to afford 4-polyhydroxyalkylpyrimidin-2-ones(thiones) in excellent yields. This is a one-pot Montmorillonite K-10 clay-catalyzed amine-driven process proceeding under solvent-free microwave irradiation conditions.     

Confined acoustic modes and spectral determination of network connectivity: Raman signatures of nanometric structure in g-GexSe1−x

Low-temperature Raman scattering results are presented on three glass compositions of Ge_xSe_1−x (15, 20, and 27 At. Ge%), and conciled with their reported structural data. The acoustic range is marked by the absence of Boson peak, and features discrete modes corresponding to nanometric dynamic aggregates. First sharp diffraction peak (FSDP) in structure factor S(k), due to Ge-Ge correlations brought about by shared Ge[Se_1/2]₄ tetrahedra medium-range structures, signifies 3D networking of Se-chains. A measure of volume-fraction of these entities determined from the FSDP area, and their number density ρ_MRS∝(k³Area)_FSDP is found to relate directly to the network connectivity, defined from optical Raman spectra in terms of the degree of cross-linking of Se-chains.     

A Comvewiemt Synthesis of 1-Aminopolycycloalkames and Their Tosylate Salts

Syntheses of oridgehead 4-amino-l-bromopentacy-clo[4.3.0.0^2.5 O^3,8.O^4,7]nonan-9-one ethyl ene acetal (6), 4-iodocubyl-l-ammonium tosylate (8) and 1-adamantane ammonium tosylate (10) are described.     

Electron-electron interactions and the electrical resistivity of lithium at low temperatures

The electron-electron interactions in lithium metal have been examined keeping in view the recent developments. The contribution of the electron-electron Umklapp scattering processes in the electrical resistivity of lithium at low temperatures has been evaluated using a simplified spherical Fermi surface model with isotropic transition probability. Our values of the electrical resistivity so obtained compare fairly well with the experimental results for lithium.