Melting, solidification and solid-state transformation of the intermetallic Ni3Sn compound were investigated in situ using synchrotron high-energy X-ray diffraction. It was observed that the compound undergoes a hexagonal to cubic transition before melting. In solidification, a disordered cubic phase crystallizes from the liquid at a large undercooling but it is reordered prior to bulk solidification. In melting and solidification, forced or natural flows are active bringing about significant changes of crystal orientations. These in situ observations provided insights into phase transformations of Ni3Sn at elevated temperatures and their roles in formation of metastable microstructure consisting of coarse grains and subgrains.

Let $p$ be a prime. In this paper, we present a detailed $p$-adic analysis on factorials and double factorials and their congruences. We give good bounds for the $p$-adic sizes of the coefficients of the divided universal Bernoulli number ${B}_{n} / n$ when $n$ is divisible by $p- 1$. Using these, we then establish the universal Kummer congruences modulo powers of a prime $p$ for the divided universal Bernoulli numbers ${B}_{n} / n$ when $n$ is divisible by $p- 1$.

We introduced our preliminary results of chromospheric activity of late-type stars based on the stellar spectrum of the pilot survey of the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST, also called Guo Shou Jing telescope). We have found 1151 active M stars from 17471 M samples using the chromospheric active indicator of the Hα line.

A Au colloid was prepared in a 5 mM HAuCl4 solution through irradiation with a focused infrared femtosecond laser at 800 nm. The Au colloid was characterized by absorption spectra, transmission electron microscopy, and x-ray diffraction analysis. The appearance of absorption peak around 526 nm in the absorption spectra and the wine-red color of sample solution HAuCl4 under focused laser irradiation verified the formation of Au colloid. The solution color changed in the order of yellow → orange → wine-red due to the local formation of Au nanoparticles near the focus. The pulse energy, focus position of laser beam, and solvent composite play important roles in formation, grain size, and stability of the Au colloid. A mechanism for the precipitate of Au nanoparticles was proposed, and a multiphoton process of femtosecond laser was involved.

Laser-induced vaporization of ceramics shows promise as a technique for the deposition of thin films of these materials. Critical to the utility of this technique is an understanding of the laser-material interaction, plume formation and dynamics, material transport and how variations in the vaporization conditions affect the deposited film. Lead zirconate titanate (PZT, Zr/Ti-47/53) targets were irradiated using a q-switched Nd:YAG laser (15 ns, 100 mJ at 1.064 /μm) . The deposition chamber was maintained at a pressure of 100 mTorr oxygen. Material from the plume was collected on silicon wafer substrates, suspended 1.0 - 3.0 cm above the target. The films were characterized by SEM/EDX, TEM, x-ray diffraction and electrical measurements before and after annealing. Very thin films were deposited on carbon coated metal grids for observation in the TEM using a hot stage to study crystallization.Temporally and spatially resolved spectra of the light emitted by the laser-generated plume were obtained with an optical multichannel analyzer (0MA) to yield information on the plume generation and chemistry of the deposition process. These spectra indicate that under these conditions a plasma is created above the target surface which persists for -100 ns after the laser pulse.