Thermally-assisted milling and hydrogenolysis for synthesizing ultrafine MgH2with destabilized thermodynamics.

A novel process has been developed to synthesize MgH2nanoparticles by combining ball milling and thermal hydrogenolysis of di-n-butylmagnesium (C4H9)2Mg, denoted as MgBu2. With the aid of mechanical impact, the hydrogenolysis temperature of MgBu2in heptane and cyclohexane solution was considerably lowered down to 100 °C, and the MgH2nanoparticles with an average particle size ofca.8.9 nm were obtained without scaffolds. The nano-size effect of the MgH2nanoparticles causes a notable decrease in the onset dehydrogenation temperature of 225 °C and enthalpy of 69.78 kJ mol-1 · H2. This thermally-assisted milling and hydrogenolysis process may also be extended for synthesizing other nanomaterials.

Dependence of DNA electronic structure on environmental and structural variations.

We present experimental and theoretical evidence that varying the local environment and physical structure of dried DNA has a direct impact on its electronic structure. By preparing samples of DNA in various solutions, it was possible to alter the type of ions present during the production of the DNA samples. These variations resulted in differences in the local chemical environment of the dried DNA molecules. X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) were used to probe the variations in the electronic structure of DNA samples. DFT calculations of a stack of 10 adenine (A)-thymine (T) nucleobase pairs show that slight structural variations in stacking height have a direct influence on the electronic structure and result in changes to the HOMO-LUMO gap. The effects of these differences in the local environment on the electronic structure are discussed and are related to the results of conductivity measurements of DNA.

Microstructure of MmM(5)/Mg multi-layer hydrogen storage films prepared by magnetron sputtering.

Multi-layer hydrogen storage thin films with Mg and MmNi3.5(CoAlMn)1.5 (here Mm denotes La-rich mischmetal) as alternative layers were prepared by direct current magnetron sputtering. Transmission electron microscopy investigation shows that the microstructure of the MmNi3.5(CoAlMn)1.5 and Mg layers are significantly different although their deposition conditions are the same. The MmNi3.5(CoAlMn)1.5 layer is composed of two regions: one is an amorphous region approximately 4 nm thick at the bottom of the layer and the other is a nanocrystalline region on top of the amorphous region. The Mg layer is also composed of two regions: one is a randomly orientated nanocrystalline region 50 nm thick at the bottom of the layer and the other is a columnar crystallite region on top of the nanocrystalline region. These Mg columnar crystallites have their [001] directions parallel to the growth direction and the average lateral size of these columnar crystallites is about 100 nm. A growth mechanism of the multi-layer thin films is discussed based on the experiment results.