Optimizing electromagnetic enhancement of flexible nano-imprinted hexagonally patterned surface-enhanced Raman scattering substrates.

The production of inexpensive, large-scale, uniform substrates for surface-enhanced Raman scattering (SERS) is a key to popularize its usage in chemical and biological detection. We demonstrate a flexible nano-imprinted hexagonally patterned SERS-active substrate. Its electromagnetic enhancement factor was optimized by the thickness adjustment of its silver over-coated film. The experimental data show a good correspondence with the theoretical prediction. Such substrate was shown to exhibit high uniformity and reproducibility with a variation of less than 2%, offering a potential of greatly exploiting such substrate in infield biocide monitoring.

Impaired skin wound healing in lumican-null mice.

BACKGROUND: Previous studies have demonstrated that the lack of lumican delayed corneal wound healing in lumican-null (Lum(-/-) ) mice. This defect is rescued by the addition of glycosylated lumican core protein to the injured corneas. OBJECTIVES: We examined the hypothesis that lumican is also required for the healing of cutaneous wounds using Lum(-/-) mice. METHODS: We demonstrated the basic thinner skin phenotypes in Lum(-/-) mice at different time points and the changes in arrangement of collagen fibres by transmission electron microscopy (TEM). A full skin thickness wound was generated by punch biopsy (6 mm diameter) in experimental Lum(-/-) and wild-type mice. The closure of injured skin was measured after various periods of time (3, 6, 12, 18 days). Specimens of injured and uninjured skin (serving as control) were then subjected to morphological examination with haematoxylin and eosin and Masson trichrome stains, and by TEM. Immunohistochemical staining with anti-CD68 antibody was used to assess the presence of macrophages in injured skin healing for various periods of time. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to elucidate the transforming growth factor (TGF)-ß1-induced myofibroblast phenotypic genes. RESULTS: Skin of adult Lum(-/-) mice (3 months and older) was much thinner (40% less) than that of age-matched wild-type mice. This phenomenon was aggravated in older mice. TEM revealed disoriented and irregular collagen fibrils in the dermis of Lum(-/-) mice. Delayed wound healing with an increase in inflammatory macrophages was compatible with the delayed response of the expression of TGF-ß1, type I collagen α1 and fibronectin at the mRNA level by semiquantitative RT-PCR in the Lum(-/-) mice. CONCLUSIONS: Our data demonstrate that lumican plays pivotal roles in skin collagen fibrillogenesis and wound healing.

Recording Bessel-like beam shapes generated by plasmonics lens.

In our study, we spun a negative photoresist layer on top of a plasmonic lens which was formed by adopting a metallic ring structure with a nano-scale width opening. We recorded the beam shape of the Bessel-like beam emitting from the plasmonic lens which formed a high aspect ratio structure. We found that the high aspect ratio structure was higher after exposure as the inner and outer diameter had increased. In addition, we used an oblique incidence on the negative resist metallic ring structure to produce an inclined micro-structure. Different exposure results were obtained with the two different metal thicknesses. Therefore, in our study, we not only proved that it is possible to record the shape of a Bessel-like beam, but we also demonstrated that it is possible to create a plasmonic lens which is capable of creating a high aspect ratio structure through exposure.

Fourier analysis of surface plasmon waves launched from single nanohole and nanohole arrays: unraveling tip-induced effects.

The authors report the investigation of surface plasmon waves (SPW) generated by single nanohole and nanohole arrays. Scattering-type scanning near-field microscopy is used to directly observe near-field distribution. The images after Fourier transformation display characteristic patterns that match with the derived analytic formula. The correspondence helps to identify the role of the scanning tip in generating SPW, making possible of the removal of this tip-induced effect. This study provides a means to perform in-depth investigation on surface plasmon polaritons.

Enhancing intensity of emitted light from a ring by incorporating a circular groove.

We fabricated a ring containing a single circular groove (RCG) on silver film and which was supported on a glass substrate. We found that by changing the mean radius of the circular groove, the light intensity emitted from the RCG can be modulated by using the scattering light from the circular groove. In addition, we also fabricated circular grooves with the same depth but of different widths so that we could examine the scattering light behavior of the grooves. Herein, we propose a theoretical model which takes into account the amplitude modulation of the cylindrical waves. Our results showed that our proposed model agreed well with the experimental results.

Similarities and differences for light-induced surface plasmons in one- and two-dimensional symmetrical metallic nanostructures.

Two types of double-sided nanostructure, one possessing a slit aperture with parallel grooves and the other possessing a circular aperture with concentric grooves, were fabricated to examine the similarities and differences of their diffraction behavior in one-dimensional (1-D) and two-dimensional (2-D) nanostructures. Based on the projection-slice theory, we conjecture that the surface plasmons in these two different nano-scale grooves possess similar modes. A localized surface plasmon (LSP) was used to examine the transmission characteristics induced by the apertures. The transmission characteristics of the slitted nanostructure and the circular nanostructure aperture were then measured. We coupled the transmission spectra measured from these two apertures with a 1-D parallel groove transmission curve simulated by a 1-D rigorous coupled wave analysis. Measured spectra results show reasonable agreement with the simulated data. We propose that the apparent blueshift observed in the peak frequency of a 2-D nanostructure is due to the difference in the shape of the aperture and the spot transmission characteristics of 1-D and 2-D systems as induced by a LSP.

Beaming light from a subwavelength metal slit surrounded by dielectric surface gratings.

In this article, we demonstrate that a subwavelength metal slit surrounded by dielectric surface gratings possesses a directional beaming effect. We propose a surface plasmon diffraction scheme to explain the three kinds of beaming conditions. The numerical simulations of the illustrative structures undertaken used a Finite Difference Time Domain (FDTD) Method and a Rigorous Coupled Wave Analysis (RCWA) Method. Our simulations were found to be consistent and in agreement with the experimental results. In comparison with other metal structures, we find that dielectric metal structures offer better performance as well as the advantage of being able to be efficiently mass produced for large volume industrial applications.

Folliculosebaceous cystic hamartoma arising within a port-wine stain.

A 34-year-old woman presented with 2-year history of a dome-shaped papule on a well-circumscribed, thickened, port-wine stain on the left side of the chin. Squeezing on the port-wine-stain plaque revealed many comedos within dilated follicular orifices. The papule was excised and submitted for histological examination. Histopathological study showed a lobular neoplasm, comprising dilated, cystic pilosebaceous structures surrounded by fibrous stroma, bearing the characteristics of folliculosebaceous cystic hamartoma. The reported case shows that, in addition to the vascular nature, both ectodermal and mesenchymal abnormalities may be involved in port-wine stains.

Perforated Meckel's diverticulum in a neonate.

A case of Meckel's diverticulum is reported in an eight-day-old male baby, the youngest patient to have had this condition at National Taiwan University Hospital. The baby had been affected by bilious vomiting of 3 days' duration and abdominal distension before being brought to the hospital. A perforated Meckel's diverticulum was found during emergency laparotomy. The resected Meckel's diverticulum did not contain ectopic tissue. The narrow lumen and narrow base of the diverticulum was thought to be the cause of poor self-emptying and subsequent acute inflammation and perforation.

[Rearing trial of a feed for Shiba goats].

Shiba goats are among the widely used for research purposes as laboratory animals and there is an increasing need for development of a suitable feed of reasonably constant nutrient composition and quality in pellet form for them. Preliminary studies yielded a pellet feed satisfactorily palatable and adequate as a maintenance ration for this species. The present experiments were conducted to assess the pellet feed for usefulness in rearing Shiba goats, in comparison with a conventional ration which has long been used at the Stock Farm of Tokyo University. No significant intergroup differences were observed as to VFA proportions in the rumen fluid, hematologic parameters or blood chemical constituents between the pellet feed and conventional ration. Animals maintained on the experimental pellets ad libitum displayed a significant decrease in apparent digestibility.