F2 laser deposition of CdTe microcrystallites-dopedfluoropolymer thin films

Crystalline thin films of polytetrafluoroethylene (PTFE) were deposited by F₂ laser (157 nm) ablation in 200 mTorr Ar gas atmosphere. Combining this PTFE thin-film process with CdTe microcrystallites synthesis in sizes of 3-7 nm via KrF laser (248 nm) ablation, CdTe microcrystallites-doped PTFE thin films were fabricated. The X-ray photoemission spectra show that the main architecture of PTFE and CdTe are maintained in the doped films. CdTe microcrystallites doped in PTFE matrix show an absorption edge shift toward higher energy and a third-order optical nonlinearity, which are induced by the quantum size effect     

Differential Sintering by Improper Selection of Sintering Parameters during Pulse Electric Current Sintering

Recently, we reported on the retention of fine-grained micro-structure in Al₂O₃/3 vol% 3Y-ZrO₂ composites using the pulse electric current sintering (PECS) technique. It was demonstrated that a high heating rate is beneficial for the retention of fine grains and homogeneous microstructure. As there are few reports on microstructural inhomogeneity and excessive grain growth in compacts densified by the PECS technique, we carried out a series of experiments on monolithic alumina by varying the sintering parameters and discussed the characteristic results. All specimens that were densified under selective sintering conditions attained high density (∼99% of the theoretical density) at 1250°3C in > 5 min. The average fracture strength of monolithic alumina was observed to be 741 ± 25 MPa and the fracture toughness was 2.2 MPa.m <^1/2, and these were reasoned out to small grains. However, compacts sintered under very low compaction pressure attained ∼92%-93% of the theoretical density, and these specimens had undesirable microstructural inhomogeneity owing to differential sintering. Hence, in the present study, we address the problem of differential sintering.     

Effects of ultrasonic irradiation on crystallization behavior of tripalmitoylglycerol and cocoa butter

Effects of application of ultrasonic power (20 kHz, 100 W) on the crystallization behavior of tripalmitoylglycerol (PPP) and cocoa butter have been examined in terms of rate of nucleation and polymorphic control. High-purity PPP (>99%) and low-purity PPP (>80%) samples were employed to mimic real fat systems, which usually have higher concentrations of minor components in addition to the main component. For both the high-purity and low-purity PPP, the application of ultrasonic power accelerated the rate of nucleation as measured by induction time for the occurrence of crystals and by the number of crystals nucleated. As for the polymorphic influences, the nucleation of both the β′ and β forms was accelerated by the ultrasound, yet the β′ form nucleation was more accelerated when the low-purity PPP samples were employed. As for cocoa butter, sonication for a short period accelerated the crystallization of Form V. The present results indicate that ultrasound irradiation is an efficient tool for controlling polymorphic crystallization of fats.     

Fabrication of porous magnesium spinel with directional pores by unidirectional solidification

A porous magnesium spinel (MgAl₂O₄) with directional pores was fabricated by unidirectional solidification in pressurized argon and hydrogen mixed gases. Two different kinds of pores with large directional and small facet shape were formed in the solidified samples. The former pores were dominant in the porous structure. A small amount of free corundum phase was formed in the solidified porous spinel as a secondary phase by vaporization of MgO component during the solidification process. With increasing total gas pressure, the pore size of the solidified samples decreased while no change in the porosity. The porosity and pore size of the samples increased with increasing hydrogen partial pressure. The porosities of the samples fabricated under 10%H₂–90%Ar and 1%H₂–99%Ar mixed gases were 30 and 10%, respectively, and that under Ar atmosphere was very low, non-porous.     

Preparation of long sticky ends for universal ligation-independent cloning: Sequential T4 DNA polymerase treatments

Ligation-independent cloning (LIC) is a useful method for efficient directional cloning of a PCR product. LIC requires a specially designed vector containing a long stretch of sequence that is missing any one of the four nucleotides. When the linearized vector is treated with T4 DNA polymerase, in the presence of the absent base, long single-stranded overhangs are generated that are suitable for cloning. In this study, long and efficient sticky ends for LIC were produced by sequential T4 DNA polymerase treatments at non-specific sequences on a commercially available vector. All restriction enzyme sites become available in the current LIC.