Ultrasound-enhanced mass transfer in Halal compared with non-Halal chicken

BACKGROUND: Halal foods are often perceived as wholesome products that are specially selected and processed to achieve the highest standards of quality. In this study, dye penetration from an aqueous solution of methylene blue (1 mol L^?1) was used as a model for the marination process of Halal and non‐Halal chicken breast. RESULTS: The effect of dye penetration was evaluated by three techniques: (1) the mass of methylene blue solution in the samples was quantified by mass gain, (2) the amount of dye absorbed was determined by spectroscopy and (3) the penetration distance of dye inside the samples was measured. For non‐Halal meat, ultrasound increased the amount of dye inside the samples by 6 and 13% after 15 and 30 min respectively. The effect on Halal meat was much more pronounced, with an increase in dye uptake of over 60% being observed for both time periods. CONCLUSION: Dye penetration is an indication of meat permeability and so can be used as an estimate of marinading of meat. Thus the use of high‐power ultrasound has potential in poultry‐processing methods, in particular that of Halal chicken marination. Copyright © 2010 Society of Chemical Industry     

Ultrasensitive detection of Ebola matrix protein in a memristor mode

Nano Research - We demonstrate the direct biosensing of the Ebola VP40 matrix protein, using a memristor mode of a liquid-integrated nanodevice, based on a large array of honeycomb-shaped silicon...     

Light emitting mechanisms dependent on stoichiometry of Si-rich-SiN<Subscript>x</Subscript> films grown by PECVD

Light emission and morphology of silicon-rich silicon nitride films grown by plasma-enhanced chemical vapor deposition were investigated versus film’s stoichiometry. The excess silicon content in the films was controlled varying the NH₃/SiH₄ gas flow ratio from 0.45 up to 1.0. High-temperature annealing was employed to form the silicon quantum dots (QDs) and to enhance the photoluminescence (PL) in visible spectral range. The PL spectrum was found to be complex. The competition of five PL bands leads to the non-monotonous variation of total PL peak position in the range of 1.55–2.95 eV when the Si excess content increases. The shape of PL spectra depends also on an excitation light wavelength. It is shown that for the films fabricated with R ≤ 0.56 and R ≥ 0.67 the dominant contribution into PL spectra is given by native SiN_x defects, whereas in the films obtained with R = 0.59–0.67 the Si-QDs form the main radiative channel. The highest PL intensity is detected in Si-rich SiN_x films grown at R = 0.59–0.67 as well. PL mechanisms are discussed in terms of the contribution of different radiative channels in the light emission process that can show the ways for the optimization of SiN_x light-emitting properties.     

Schottky barrier-based silicon nanowire pH sensor with live sensitivity control

We demonstrate a pH sensor based on ultrasensitive nanosize Schottky junctions formed within bottom-up grown dopant-flee arrays of assembled silicon nanowires. A new measurement concept relying on a continuous gate sweep is presented, which allows the straightforward determination of the point of maximum sensitivity of the device and allows sensing experiments to be performed in the optimum regime. Integration of devices into a portable fluidic system and an electrode isolation strategy affords a stable environment and enables long time robust FET sensing measurements in a liquid environment to be carried out. Investigations of the physical and chemical sensitivity of our devices at different pH values and a comparison with theoretical limits are also discussed. We believe that such a combination of nanofabrication and engineering advances makes this Schottky barrier-powered silicon nanowire lab-on-a-chip platform suitable for efficient biodetection and even for more complex biochemical analysis.     

Light Emission in Nd Doped Si-Rich HfO 2 Films Prepared by Magnetron Sputtering

Hafnium oxide films doped with Si and Nd atoms were produced by radio-frequency magnetron sputtering of a HfO2 target topped with calibrated Si and Nd2O3 pellets in pure argon plasma followed by an annealing in nitrogen atmosphere during tA = 15 min at different temperatures (TA = 800–1100°C). The evolution of structural, chemical and luminescent properties of the films with TA was studied by means of the scanning electronic microscopy (SEM), x-ray diffraction (XRD), Raman scattering, energy dispersive x-ray spectroscopy and photoluminescence (PL) methods. The SEM method revealed that the surface of as-deposited film consists of the grains with the mean size of 20–60 nm. Annealing treatment stimulated the growing of the grains (up to 100 nm in lateral size) and film densification. The presence of Si-rich phase was detected by Raman scattering spectra in as-deposited films and those annealed at low TA. The TA increase results in the phase separation process. For the films annealed at TA > 950°C, the tetragonal HfO2 and SiO2 phases were clearly detected by the XRD method. PL spectra of the films were found to be complex. They demonstrated several PL bands in the visible (400–750 nm) and infrared (800–1430 nm) spectral ranges. Besides PL components caused by the recombination of carriers via host defects, the PL signal from Nd3+ ions due to the transition in the 4f inner electronic shell was observed. The highest Nd3+ related PL signal was observed for the films annealed at TA = 950°C. Peculiarities of PL excitation and the mechanism of the phase separation are analysed and discussed.     

Microstructure and optical properties of Pr3+-doped hafnium silicate films

In this study, we report on the evolution of the microstructure and photoluminescence properties of Pr³⁺-doped hafnium silicate thin films as a function of annealing temperature (T_A). The composition and microstructure of the films were characterized by means of Rutherford backscattering spectrometry, spectroscopic ellipsometry, Fourier transform infrared absorption, and X-ray diffraction, while the emission properties have been studied by means of photoluminescence (PL) and PL excitation (PLE) spectroscopies. It was observed that a post-annealing treatment favors the phase separation in hafnium silicate matrix being more evident at 950°C. The HfO₂ phase demonstrates a pronounced crystallization in tetragonal phase upon 950°C annealing. Pr³⁺ emission appeared at T_A = 950°C, and the highest efficiency of Pr³⁺ ion emission was detected upon a thermal treatment at 1,000°C. Analysis of the PLE spectra reveals an efficient energy transfer from matrix defects towards Pr³⁺ ions. It is considered that oxygen vacancies act as effective Pr³⁺ sensitizer. Finally, a PL study of undoped HfO₂ and HfSiO_x matrices is performed to evidence the energy transfer.     

Raman scattering,emission and crystalline phase evolutions in Nd-doped Si-rich HfO2:N films

Journal of Materials Science: Materials in Electronics - The impact of the evolution of crystalline phases with thermal annealing on the Raman scattering and emission spectra of the Nd-doped HfO2...     

Aerosol optical depth retrieval over snow using AATSR data

Aerosol observations over the Arctic are important because of the effects of aerosols on Arctic climate, such as their direct and indirect effects on the Earth's radiation balance and on snow albedo. Although information on aerosol properties is available from ground-based measurements, passive remote sensing using satellite measurements would offer the advantage of large spatial coverage with good temporal resolution, even though, due to light limitations, this is only available during the Arctic summer. However, aerosol optical depth (AOD) retrieval over the Arctic region is a great challenge due to the high reflectance of snow and ice and due to the high solar zenith angle. In this article, we describe a retrieval algorithm using Advanced Along-Track Scanning Radiometer (AATSR) data, a radiometer flying on the European Space Agency (ESA) Environmental Satellite (ENVISAT), which offers two views (near nadir and at 55° forward) at seven wavelengths in the visible thermal-infrared (VIS-TIR). The main idea of the Dual-View Multi-Spectral (DVMS) approach is to use the dual view to separate contributions to reflectance measured at the top of the atmosphere (TOA) due to atmospheric aerosol and the underlying surface. The algorithm uses an analytical snow bidirectional reflectance distribution function (BRDF) model for the estimation of the ratio of snow reflectances in the nadir and forward views, as well as an estimate of the atmospheric contribution to TOA reflectance obtained using the dark pixel method over the adjacent ocean surface, assuming that this value applies over nearby land surfaces in the absence of significant sources across the coastline. An iteration involving all four AATSR wavebands in the visible near-infrared (VIS-NIR) is used to retrieve the relevant information. The method is illustrated for AATSR overpasses over Greenland with clear sky in April 2009. Comparison of the retrieved AOD with AErosol Robotic Network (AERONET) data shows a correlation coefficient of 0.75. The AODs retrieved from AATSR using the DVMS approach and those obtained from AERONET data show similar temporal trends, but the AERONET results are more variable and the highest AOD values are mostly missed by the DVMS approach. Limitations of the DVMS method are discussed. The pure-snow BRDF model needs further correction in order to obtain a better estimation for mixtures of snow and ice.     

The structure of Si-SiO2 layers with high excess Si content prepared by magnetron sputtering

Si-SiO₂ layers with high excess Si content prepared by magnetron co-sputtering of Si and SiO₂ and subsequently annealed were studied by electron paramagnetic resonance and photoluminescence methods. It was shown that adding oxygen during the deposition run or aging in air of as-deposited films influences the characteristics of the oxide layer surrounding the silicon crystallites. It was found that for layers with more than 55 vol.% of excess silicon the silicon crystallites are oriented. After high-temperature annealing not all the excess silicon was in crystalline form but part of it was in the amorphous phase. The depth distribution of the crystallites was found to be homogeneous while the distribution of amorphous silicon has a maximum around the middle of the layer.