Extremely simple, rapid and highly efficient transformation method for the yeast Saccharomyces cerevisiae using glutathione and early log phase cells

In the presence of polyethylene glycol (PEG), budding cells of Saccharomyces cerevisiae in the early log phase were transformed by exogenous plasmid DNA without additional specific chemical or physical treatments. This capacity of the yeast cells to become competent was strictly dependent on the growth phase, being induced in the early log phase, becoming maximum between the early and mid log phases and then disappearing rapidly in the mid log phase. The transformation was most efficient at pH 6 and the frequency increased with increasing DNA and cell concentrations. PEGs with average molecular sizes between 1000 and 3500 showed almost the same effects and were used most efficiently at 35%. The transformation frequency of S. cerevisiae was markedly enhanced when the oxidized form of glutathione (GSSG), but not the reduced form, was included in the mixture comprising early log phase cells, plasmid DNA, and PEG, and the transformation system with GSSG could be used as a convenient transformation method for the yeast S. cerevisiae.     

Analysis of enhanced second-harmonic generation in periodic nanostructures using modified rigorous coupled-wave analysis in the undepleted-pump approximation

We present an extension of the rigorous coupled-wave analysis technique to analyze second-harmonic generation (SHG) in periodic optical nanostructures in the undepleted-pump approximation. We apply this method to analyze SHG in two example nanostructures for which we predict enhanced nonlinearity due to transverse near-field localization of the fundamental optical field in the nonlinear material. First, we examine a periodic nanostructure that yields up to twice the transmitted SHG intensity output compared with the bulk nonlinear material but only for small nanostructure depths because of mismatch of the fundamental and second-harmonic mode phase velocities. Second, we develop and analyze a modified nanostructure and find that this nanostructure concurrently achieves transverse localization and phase matching for SHG. In principle, this permits an arbitrary coherent interaction length, and for several specific nanostructure depths we predict a transmitted SHG intensity output more than two orders of magnitude greater than that of the bulk material.     

A simple derivation of the interactor matrix and its applications

An interactor matrix plays several important roles in the control system theory. In this article, we present a simple method to derive a special interactor matrix using Moore–Penrose pseudoinverse. The interactor by the proposed method has all its zeros at the origin, and has the all-pass property in the discrete-time. A systematic procedure to obtain an identity interactor, which has an lower triangular structure or has arbitrarily prespecified zeros, is also shown.     

Growth and characterization of copper nanoclusters embedded in SiC matrix

Nanocrystalline copper clusters embedded in silicon carbide were made by island growth during sputter deposition. The distribution and morphology of metal clusters were observed by high-resolution transmission electron microscopy. To investigate chemical bonding at the copper-silicon carbide interface, we studied the electronic states of copper and silicon using X-ray photoelectron spectroscopy (XPS). It was found that the formation of copper silicide was suppressed in this system and that small shifts in binding energy were observed for different sizes of clusters, which was different from the chemical shift for copper silicide formation.     

Fucoxanthin Prevents Pancreatic Tumorigenesis in C57BL/6J Mice That Received Allogenic and Orthotopic Transplants of Cancer Cells

Fucoxanthin (Fx) is a marine carotenoid with anti-inflammatory and anti-cancer properties in various animal models of carcinogenesis. However, there is currently no information on the effects of Fx in animal models of pancreatic cancer. We investigated the chemopreventive effects of Fx in C57BL/6J mice that received allogenic and orthotopic transplantations of cancer cells (KMPC44) derived from a pancreatic cancer murine model (Ptf1a^Cre/+; LSL-kras^G12D/+). Using microarray, immunofluorescence, western blot, and siRNA analyses, alterations in cancer-related genes and protein expression were evaluated in pancreatic tumors of Fx-administered mice. Fx administration prevented the adenocarcinoma (ADC) development of pancreatic and parietal peritoneum tissues in a pancreatic cancer murine model, but not the incidence of ADC. Gene and protein expressions showed that the suppression of chemokine (C-C motif) ligand 21 (CCL21)/chemokine receptor 7 (CCR7) axis, its downstream of Rho A, B- and T-lymphocyte attenuator (BTLA), N-cadherin, αSMA, pFAK(Tyr³⁹⁷), and pPaxillin(Tyr³¹) were significantly suppressed in the pancreatic tumors of mice treated with Fx. In addition, Ccr7 knockdown significantly attenuated the growth of KMPC44 cells. These results suggest that Fx is a promising candidate for pancreatic cancer chemoprevention that mediates the suppression of the CCL21/CCR7 axis, BTLA, tumor microenvironment, epithelial mesenchymal transition, and adhesion.     

Studies on high‐speed melt spinning of noncircular cross‐ section fibers. I. Structural analysis of as‐spun fibers

Flat fibers and hollow fibers were prepared through the high‐speed melt spinning of poly(ethylene terephthalate) (PET), and the structures of these fibers were compared with those of circular fibers. The cross‐sectional shape of each fiber changed to a dull shape in comparison with that of the respective spinning nozzle. The change in the cross‐sectional shape was slightly suppressed with an increase in the take‐up velocity. There was a significant development of structural variation in the cross section of flat fibers in that the molecular orientation and crystallization were enhanced at the edge. Despite the difference in the cross‐sectional shape, the structural development of flat, hollow, and circular fibers with increasing take‐up velocity showed almost similar behavior. Considering that the tensile stress at the solidification point of the spin line is known to govern the structure development of high‐speed spun PET fibers, it was speculated that the effects of the enhancement of cooling and air friction on the tensile stress at the solidification point cancel each other. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1575–1581, 2001     

A methodology to work on geometrically complex heat transfer systems: the cases of heat conduction through composite slabs

Geometrical complexity considered in the present study is characterized by a large degree of freedom in placement of constituents in a composite system. The constituent sizes are not negligibly small compared to the system’s expanse, so approximations of their configurations and placement patterns by some simple equivalents are not feasible. Numerical analysis is a means to estimate heat transfer performance of the system, but a strategy is required to navigate through a vast number of possible constituent patterns to find ones that produce higher heat transfer performance. In the proposed methodology the constituent pattern is captured as a two-dimensional mosaic image of solid cells embedded in a substrate. On an image assumed as a starter, the singular-value decomposition (SVD) analysis is performed to find its (SVD) building block elements. By shuffling the building block elements variants of the starter image are created. Heat transfer analysis is performed on sample systems that are picked up from the ensemble of variants. Using the Taguchi method and through a genetic algorithm-type reasoning, those element arrangements that do not significantly affect the heat transfer performance are weeded out. The methodology is demonstrated on the cases of heat conduction through composite slabs.