Enhanced sensitivity of cancer cell using one dimensional nano composite material coated photonic crystal

We theoretically analyze the detection of a cancer cell in the one-dimensional photonic crystal by infiltrating different sample cells in the cavity layer. The defect modes appear in their transmission spectra only if the nanocomposite layers are included on either side of the cavity layer. This analysis is carried out by a dielectric constant and the transmittance peak of the cancer cell is compared with the normal cell. The transmittance peak shifts are analyzed with various filling factors for optimization purposes. Through the shifting spectrum, the sensitivity of cancer cell from the normal cell is obtained from a minimum of 42 nm/RIU to a maximum of 43 nm/RIU.

     

Application of citric acid as natural adhesive for wood

The development of natural adhesives derived from nonfossil resources is very important for the future. Besides, it is desirable to be safe adhesives without using harmful chemical substances. In this study, application of citric acid as a natural adhesive was investigated. Citric acid powder and bark powder obtained from Acacia mangium were used as raw materials. Citric acid powder was mixed with the bark powder, and the resulting powder mixture was poured into a metal mold. The mold was hot‐pressed at 180°C and 4 MPa for 10 min, and a bark molding was then obtained. The specific modulus of rupture and modulus of elasticity values of the molding containing 20 wt % citric acid were 18.1 MPa and 4.9 GPa, respectively. The molding did not decompose during a repeated boiling treatment. To clarify the effect of tannin on the adhesiveness of molding, bark was separated into tannin and residue. The molding was not obtained while using the tannin due to the marked fluidity, whereas it was obtained while using the residue, the same as while using the bark. It was considered that components other than tannin contributed to the adhesiveness. Based on the results of Fourier transform infrared spectra, the formation of ester linkages between carboxyl groups derived from citric acid and hydroxyl groups in the bark was confirmed. Accordingly, citric acid brought an adhesion by chemical bonding, and it could be used as a safe natural adhesive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of TiO2 nanoparticles at low hydrothermal temperature and its performance for DSSC sensitized using natural dye extracted from Melastoma malabathricum L. seeds

Efficiency of a dye‐sensitized solar cell (DSSC) device depends on its semiconductor layer and the sensitizing dye to absorb the light. This work seeks to obtain the best solvent for the natural dye extraction from Melastoma malabathricum L. seeds. The extracted dye is used as sensitizer on TiO₂ nanoparticles produced via hydrothermal but optimized at relatively low temperature. Infrared characterization of the extracted dyes showed differences in functional groups using different solvents, whereas ultraviolet visible examination of the dyes showed differences in intensity along the spectrum ranges of 600 to 400 nm with maximum absorption around 550 to 500 nm. Thermal analysis revealed that the natural dye should be stable around room temperature. Analysis on the synthesized TiO₂ nanoparticles showed that the average crystallite size reported in the previous work is consistent with crystallite sizes observed in the transmission electron microscope images. Photoactivity examination showed that the DSSC sensitized using natural dye extracted with ethanol containing 20% distilled water on TiO₂ synthesized at 150°C has an efficiency of 5.7%, whereas the one on commercial TiO₂ P25 Degussa has an efficiency of 3.0%. The DSSC device sensitized using commercial dye on TiO₂ synthesized at 150°C has an efficiency of 4.4%, whereas the one on TiO₂ P25 Degussa has an efficiency of 4.0%. This result is promising for further development of the DSSC device using TiO₂ nanoparticles synthesized at low hydrothermal temperature and sensitized with the natural dye.     

Slab waveguide with conducting interfaces as an efficient optical sensor: TE case

In this paper, three-layer slab waveguide structure is treated for optical sensing applications. Four waveguide configurations including different guiding films and analytes are assumed. A conducting two-dimensional free charge layers with a surface conductivity is assumed to exist at the substrate/film and film/cladding interfaces. The sensing sensitivity of the proposed structure to any changes in an analyte refractive index uniformly distributed in the cladding layer is investigated. Positive as well as negative surface conductivities are considered. It is found that utilizing positive surface conductivity can enhance the sensitivity, whereas using negative values of the surface conductivity reduces the sensitivity.     

Peak type metal-clad waveguide sensor using negative index materials

A four-layer metal-clad structure was considered as an optical sensor for refractometry applications. The structure had a negative index material (NIM) as a core layer. The structure parameters were chosen for so that the reflectance profile of the proposed structure shows a sharp peak, which is appropriate for sensing applications. The sensor was found to exhibit a considerable angular shift of the reflectance peak for small changes in the refractive index of the analyte, due to the NIM layer.     

Transient liquid phase bonding of ferritic oxide-dispersion-strengthened alloys

Joining of two ferritic oxide-dispersion-strengthened (ODS) alloys, MA956 and PM2000, using transient liquid phase (TLP) bonding is discussed. Thin-film boron coatings of different thicknesses were used as interlayers and different bond orientations with substrates cut along and normal to the direction of extrusion were studied, with postbond heat treatment and microscopic evaluation of the bonds. Microstructural continuity was achieved in bonds when joining fine grain substrates cut along the direction of extrusion.     

Attachment of Listeria monocytogenes to an austenitic stainless steel after welding and accelerated corrosion treatments

Austenitic stainless steels, widely used in food processing, undergo microstructural changes during welding, resulting in three distinctive zones: weld metal, heat-affected zone, and base metal. This research was conducted to determine the attachment of Listeria monocytogenes in these three zones before and after exposure to a corrosive environment. All experiments were done with tungsten inert gas welding of type 304 stainless steel. The four welding treatments were large or small beads with high or low heat. After welding, all surfaces were polished to an equivalent surface finish. A 10-microl droplet of an L. monocytogenes suspension was placed on the test surfaces. After 3 h at 23 degrees C, the surfaces were washed and prepared for scanning electron microscopy, which was used to determine attachment of L. monocytogenes by counting cells remaining on each test surface. In general, bacteria were randomly distributed on each surface type. However, differences in surface area of inoculum due to differences in interfacial energy (as manifested by the contact angle) were apparent and required normalization of bacterial count data. There were no differences (P > 0.05) in numbers of bacteria on the three surface zones. However, after exposure to the corrosive medium, numbers of bacteria on the three zones were higher (P < 0.05) than those on the corresponding zones of noncorroded surfaces. For the corroded surfaces, bacterial counts on the base metal were lower (P < 0.05) than those on heat-affected and weld zones.     

Goos-Hänchen shift as a probe in evanescent slab waveguide sensors

The present paper deals with three-layer planar waveguide optical sensor. Different from the conventional slab waveguide sensors in which the effective refractive index of the propagating mode is taken to be the probe for detection changes in the analyte refractive index, we adopt Goos-Hänchen (GH) shift as the sensing probe for the proposed sensor. We show that the GH shift is strongly dependent on the refractive index of the cladding, thus it is a good candidate for detection changes in the analyte refractive index. We present and study the sensitivity of the GH shift at the cladding-film and substrate-film interfaces. It is found that GH shift has a high sensitivity and can be used for versatile optical slab waveguide sensors.     

Theoretical analysis of TM nonlinear asymmetrical waveguide optical sensors

An extensive analytical analysis is carried out to investigate TM nonlinear asymmetrical waveguide sensors. The structure consists of a thin film embedded between two nonlinear media. The effect of the nonlinearity of the cladding and the substrate on the sensitivity of the sensor is studied. A comparison between the proposed nonlinear sensor and the conventional linear sensor is presented to show that nonlinear sensors have higher sensitivities. The condition required to maximize the sensitivity is also derived to provide the designer with the optimum structure of the proposed nonlinear sensor.     

Effects of aqueous, dietary and combined exposures of cadmium to Ceriodaphnia dubia

While effects of water-borne metal exposures on freshwater animals have been well documented, the effect of dietary metal exposure is less understood but is gaining importance. However, little attention has been given to the importance of combining both exposure pathways. In this study, we compared effects of aqueous ('water only'), dietary ('food only') and combined ('water+food') exposures of cadmium to the freshwater cladocerans, Ceriodaphnia dubia. Major test endpoints included survival, feeding rate and reproduction. The C. dubia three-brood reproduction tests were conducted according to the United States Environmental Protection Agency (U.S. EPA) methods. Three exposure scenarios were used: aqueous, dietary, and combined aqueous and dietary exposures. Results showed that all three exposures affected survival, feeding rate and reproduction of C. dubia. Interestingly, combined exposure showed contribution effects of aqueous and dietary exposures. Lower cadmium concentrations were needed in combined exposure to produce effects as compared to higher concentrations in aqueous or dietary exposure alone. These results demonstrated the potential importance of dietary and combined exposures for consideration of cadmium regulation and risk assessment of metals.