Calorimetric Study of Thermal Denaturation of Superoxide Dismutase

The thermal denaturation of superoxide dismutase (SOD) from bovine erythrocytes was studied at various pH values of different buffers and at various concentrations of solutions of two neutral salts by differential scanning calorimetry. The experiments performed indicate that the PIPES is a buffer non-coordinating with the SOD, and that the binding of the anions studied influences more or less the thermal denaturation of SOD, but the effect on the oxidation form of SOD is more apparent. A new conformer of SOD with lower thermostability was discovered by the experiments performed in different buffers at certain pH values higher than the isoelectric point of SOD, or at higher concentrations of neutral salt solutions. The new conformer may be converted irreversibly into the usual conformer with high thermostability during heating. Based on the thermodynamic parameters obtained in distilled water and by thermodynamic analysis using the Ooi's model, it is revealed that the large enthalpy △Hdc contributed by     

Soft‐Chemical Exfoliation Route to Layered Cobalt Oxide Monolayers and Its Application for Film Deposition and Nanoparticle Synthesis

A colloidal suspension of exfoliated, layered cobalt oxide nanosheets has been synthesized through the intercalation of quaternary tetramethylammonium ions into protonated lithium cobalt oxide. According to atomic force microscopy, exfoliated nanosheets of layered cobalt oxide show a plateau‐like height profile with nanometer‐level height, underscoring the formation of unilamellar 2D nanosheets. The exfoliation of layered cobalt oxide was cross‐confirmed by X‐ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The maintenance of the hexagonal in‐plane structure of the cobalt oxide lattice after the exfoliation process was evidenced by selected‐area electron diffraction and Co K‐edge X‐ray absorption near‐edge structure analysis. The zeta‐potential measurements clearly demonstrated the negative surface charge of cobalt oxide nanosheets. Adopting the nanosheets of layered cobalt oxide as a precursor, we were able to prepare the monodisperse CoO nanocrystals with a particle size of ≈10 nm as well as the heterolayered film composed of cobalt oxide monolayer and polycation.     

Spectroscopic study on the interaction between[Hg（SCN）4]2- and hemoglobin

The interaction between[Hg（SCN）₄]^2- and hemoglobin（Hb） under conditions that simulate a physiological environment was investigated by UV-vis spectroscopy,fluorescence spectroscopy,resonance Rayleigh scattering（RRS） spectroscopy and circular dichroism（CD） spectroscopy.The results obtained from the change of UV-vis and CD spectra,the quenching of Hb fluorescence and the enhancement of RRS intensity proved that a 10:1 type complex was formed between[Hg（SCN）₄]^2- and Hb.The possible mechanism suggested for the interaction was that ten Hg（SCN）₄]^2- anions entered the four subunits of a Hb molecule to react with some residues to form an adduct by coordination and electrostatic forces.The coordination of[Hg（SCN）₄]^2- with Trp was the major cause of the fluorescence quenching of Hb.     

An ionothermal synthetic approach to porous polyoxometalate-based metal-organic frameworks

Pretty porous POMs: Ionothermal synthesis was applied to prepare porous POM-based open frameworks. The structural integrity remains unchanged until 300?°C; most importantly, the bulky tetrabutylammonium cations within their nanosized channels can be replaced by transition-metal ions through a cation-exchange process, and subsequent gas adsorption measurements confirm their permanent porosity.     

Activation and Retention: A Magnetic Resonance Probe for the Detection of Acute Thrombosis

Blood‐clot formation that results in the complete occlusion of a blood vessel (thrombosis) often leads to serious life‐threatening events, such as strokes and heart attacks. As the composition of a thrombus changes as it matures, new imaging methods that are capable of distinguishing new clots from old clots may yield important diagnostic and prognostic information. To address this need, an activatable magnetic resonance (MR) probe that is responsive to a key biochemical process associated with recently formed clots has been developed.     

Metal‐Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source

N‐methylation of amines is an important step in the synthesis of many pharmaceuticals and has been widely applied in the preparation of other key intermediates and chemicals. Therefore, the development of efficient methylation methods has attracted considerable attention. In this respect, carbon dioxide is an attractive C₁ building block because it is an abundant, renewable, and nontoxic carbon source. Consequently, we developed a highly chemoselective, metal‐free catalytic system that operates under ambient conditions for the N‐methylation of amines.