ALBERT

Description: ABSTRACT Highly oriented ZnO and Mg doped ZnO thin films were fabricated on Al 2 O 3 substrate by sputtering at room temperature. The effect of Mg doping on the structural, optical, and morphological properties of ZnO film was investigated. The intensity of (002) peak in X-ray diffraction measurements revealed the influence of Mg doping on the crystallinity and orientation of ZnO film. Photoluminescence (PL) results show that the Ultraviolet (UV) emission peak was shifted to lower wavelength side for Mg:ZnO film indicating the possibility for quantum confinement. UV–vis–NIR optical absorption revealed an improvement in optical transmittance from 70 to 85%, and corresponding optical band gap from 3.25 to 3.54 eV. Atomic force microscope (AFM) images revealed the nano-size particulate microstructure of the films. The surface topography of Mg doped ZnO film confirmed decreased grain size with large surface roughness and increased surface area, favorable for sensing. Pure ZnO and Mg doped ZnO film were used as active layer and tested for its sensing performance to hydrogen. Compared to undoped ZnO, 22 at.% Mg doped ZnO film showed much higher sensor response to H 2 at a concentration as low as 200 ppm and at a lower operating temperature of 180°C. A linear sensor response was observed for H 2 concentration in the range of 100–500 ppm. Microsc. Res. Tech., 2013 . © 2013 Wiley Periodicals, Inc.

Description: ABSTRACT ZnO films were deposited onto glass, ITO coated glass, and sapphire substrate by spray pyrolysis, and subsequently annealed at the same temperature of 400°C for 3 h. The role of substrate on the properties of ZnO films was investigated. The structural and optical properties of the films were investigated by X-ray diffractometer (XRD) and photoluminescence (PL) spectrophotometer, respectively. The surface morphology of the nanostructured ZnO film was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Crystallographic properties revealed that the ZnO films deposited on sapphire and ITO substrates exhibit a strong c -axis orientation of grains with hexagonal wurtzite structure. Extremely high UV emission intensity was determined in the film on ITO. The different luminescence behaviors was discussed, which would be caused by least value of strain in the film. Films grown on different substrates revealed differences in the morphology. ZnO films on ITO and sapphire substrates revealed better morphology than that of the film on glass. AFM images of the films prepared on ITO show uniform distribution of grains with large surface roughness, suitable for application in dye sensitized solar cells. Microsc. Res. Tech., 2013 . © 2013 Wiley Periodicals, Inc.

Description: ABSTRACT Estimates of the radii and solute concentrations of simulated microstructures containing ultrafine spherical precipitates were determined from isoconcentration surfaces and proximity histograms. The accuracy of the estimates of the solute concentrations and the radii of precipitates was found to depend on the size of precipitates. Optimized parameters for analyzing 0.5- to 2-nm-radius precipitates are proposed. The solute content of 0.5-nm-radius precipitates was not estimated correctly by this method. The accuracy of the estimates of the solute concentration and the radius of precipitates were primarily influenced by the solute concentrations of the precipitates. The ranges of error of the solute concentration in the precipitates, which are associated with the analytical limitations of the ultrafine precipitates, were determined, and the results indicated a limitation of the estimates. Microsc. Res. Tech., 2013 . © 2013 Wiley Periodicals, Inc.

Description: Functional restoration for orthopedic, systemic, or dental purposes uses a diverse range of biomaterials. Monitoring for any subsequent failures associated with pathology is vital. To this end, an alternative methodology beyond that of cutting sections by conventional microtome knife-based histomethodologies was pioneered. The method was to saw a block of tissue followed by grinding the unsupported slice to the required thickness. The sawing and grinding of unsupported bones or teeth exposed not only the specimen fragility, but also the delicacy of the associated soft tissues. Although incomplete, the significance of the technique was recognized and improvements were incorporated which persist to the present day addressing the histopathology of challenging specimens. One major improvement for preserving cellular structure as well as reducing fracture incidence was achieved by impregnating tissue samples with cross-linked resins prior to the cutting and grinding processes. Methyl and glycol methacrylate resins superseded all other choices because of the advantages of photo-initiated curing. Further pioneering work led to the formulation of increasingly appropriate resin systems and the subsequent processing protocols evolved, as clinical needs for histology-specific techniques became apparent. Over the decades, several key pioneers entered this scientific arena to develop the now established resin formulation, processing protocols, and allied applications. This has led to the commercialization of the various resin systems. The aim here is to discuss the commercially available glycol and methyl methacrylate resin systems and their practical application to a variety of important techniques used in the histological assessment of complex pathology specimens. Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Description: Analysis of the cellular distributions of coenzymes including NADH may aid in understanding a cells metabolic status. We altered serum concentration (0, 2, and 10%) to induce living myoblast cells to undergo the early stages of differentiation. Through microscopy and phasor-FLIM, we spatially mapped and identified variations in the distribution of free and bound NADH. Undifferentiated cells displayed abundant free NADH within the nucleus along with specific regions of more bound NADH. Complete serum starvation dramatically increased the fraction of bound NADH in the nucleus, indicating heightened requirement for transcriptional processes. In comparison, cells exposed to 2% serum exhibited intermediate free nuclear NADH fraction. Overall our results suggest an order of events in which a cell metabolic status alters significantly during the early stages of serum induced differentiation. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.

Description: The speed and accuracy of Förster resonance energy transfer (FRET) measurements can be improved by rapidly alternating excitation wavelengths between the donor and acceptor fluorophore. We demonstrate FRET efficiency measurements based on a fiber laser and photonic crystal fiber as the source for two-photon excitation (TPE). This system offers the potential for rapid wavelength switching with the benefits of axial optical sectioning and improved penetration depth provided by TPE. Correction of FRET signals for cross excitation and cross emission was achieved by switching the excitation wavelength with an electrically controlled modulator. Measurement speed was primarily limited by integration times required to measure fluorescence. Using this system, we measured the FRET efficiency of calmodulin labeled with Alexa Fluor 488 and Texas Red dyes. In addition, we measured two-photon induced FRET in an E 0 GFP-mCherry protein construct. Results from one-photon and two-photon excitation are compared to validate the rapid wavelength switched two-photon measurements. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.

Description: Functional restoration for orthopedic, systemic, or dental purposes uses a diverse range of biomaterials. Monitoring for any subsequent failures associated with pathology is vital. To this end, an alternative methodology beyond that of cutting sections by conventional microtome knife-based histomethodologies was pioneered. The method was to saw a block of tissue followed by grinding the unsupported slice to the required thickness. The sawing and grinding of unsupported bones or teeth exposed not only the specimen fragility, but also the delicacy of the associated soft tissues. Although incomplete, the significance of the technique was recognized and improvements were incorporated which persist to the present day addressing the histopathology of challenging specimens. One major improvement for preserving cellular structure as well as reducing fracture incidence was achieved by impregnating tissue samples with cross-linked resins prior to the cutting and grinding processes. Methyl and glycol methacrylate resins superseded all other choices because of the advantages of photo-initiated curing. Further pioneering work led to the formulation of increasingly appropriate resin systems and the subsequent processing protocols evolved, as clinical needs for histology-specific techniques became apparent. Over the decades, several key pioneers entered this scientific arena to develop the now established resin formulation, processing protocols, and allied applications. This has led to the commercialization of the various resin systems. The aim here is to discuss the commercially available glycol and methyl methacrylate resin systems and their practical application to a variety of important techniques used in the histological assessment of complex pathology specimens. Microsc. Res. Tech., 2012. © 2011 Wiley Periodicals, Inc.