Crystallization behaviour of amorphous Zr1-xCox alloys with 0.20 ≤ x ≤ 0.41

The crystallization of melt-spun amorphous Zr_1-xCo_x alloys with 0.20 ≤ x ≤ 0.41 has been studied under both isothermal and non-isothermal conditions by use of DSC-technique. Up to three peaks were observed. The crystallization temperature varies with composition from 631 K for x = 0.20 to 746 K for x = 0.41. Isothermal annealing of x = 0.41 shows that the kinetics of the crystallization can be described by the Johnson-Mehl-Avrami equation with n ≈ 2.85 at lower annealing temperatures (712.5 – 725 K) while in the temperature range 725 K to 740 K n increases with increasing annealing temperature. The phases formed during the crystallization process have been identified by means of X-ray diffraction techniques and electron microscope studies. For compositions around x = 0.33 microcrystalline phases are formed upon crystallization.     

Dual Light and Temperature Responsive Micrometer‐Sized Structural Color Actuators

Externally induced color‐ and shape‐changes in micrometer‐sized objects are of great interest in novel application fields such as optofluidics and microrobotics. In this work, light and temperature responsive micrometer‐sized structural color actuators based on cholesteric liquid‐crystalline (CLC) polymer particles are presented. The particles are synthesized by suspension polymerization using a reactive CLC monomer mixture having a light responsive azobenzene dye. The particles exhibit anisotropic spot‐like and arc‐like reflective colored domains ranging from red to blue. Electron microscopy reveals a multidirectional asymmetric arrangement of the cholesteric layers in the particles and numerical simulations elucidate the anisotropic optical properties. Upon light exposure, the particles show reversible asymmetric shape deformations combined with structural color changes. When the temperature is increased above the liquid crystal‐isotropic phase transition temperature of the particles, the deformation is followed by a reduction or disappearance of the reflection. Such dual light and temperature responsive structural color actuators are interesting for a variety of micrometer‐sized devices.     

Near‐UV activated,photostable nanophosphors for in vitro dosimetry and dynamic bioimaging

Luminescent rare earth nanoparticles exhibit superior optical stability over commonly‐used organic dyes and higher biocompatibility over quantum dots, rendering them advantageous as bioimaging nanoprobes. However, their typical excitation inhibits their broad employment with conventional fluorescence microscopes and, thus, solutions are sought to shift their activation in the long‐wavelength (near‐UV) spectral region. Here, we synthesize YVO₄:Eu³⁺ nanophosphors by flame aerosol technology to systematically study the effect of Bi³⁺ codoping on their luminescence. That way, we identify an optimal Bi‐content for sufficient near‐UV activation. These nanophosphors are highly crystalline and appeared bright red under a conventional fluorescence microscope, facilitating bioimaging with HeLa cells and in vitro dosimetry correlations in the presence and absence of serum. The nanophosphor superiority over organic‐dye‐labeled silica nanoparticles is shown during dynamic imaging for 4 h without photobleaching for the former. These YVO₄:Eu³⁺/Bi³⁺ nanophosphors can provide a non‐photobleaching tool for further dynamic nanoparticle‐cell interaction studies with conventional fluorescence microscopes. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2947–2957, 2018     

Parallel beamforming using synthetic transmit beams

Parallel beamforming is frequently used to increase the acquisition rate of medical ultrasound imaging. However, such imaging systems will not be spatially shift invariant due to significant variation across adjacent beams. This paper investigates a few methods of parallel beam-forming that aims at eliminating this flaw and restoring the shift invariance property. The beam-to-beam variations occur because the transmit and receive beams are not aligned. The underlying idea of the main method presented here is to generate additional synthetic transmit beams (STB) through interpolation of the received, unfocused signal at each array element prior to beamforming. Now each of the parallel receive beams can be aligned perfectly with a transmit beam--synthetic or real--thus eliminating the distortion caused by misalignment. The proposed method was compared to the other compensation methods through a simulation study based on the ultrasound simulation software Field II. The results have been verified with in vitro experiments. The simulations were done with parameters similar to a standard cardiac examination with two parallel receive beams and a transmit-line spacing corresponding to the Rayleigh criterion, wavelength times f-number (lambda x f#). From the results presented, it is clear that straightforward parallel beamforming reduces the spatial shift invariance property of an ultrasound imaging system. The proposed method of using synthetic transmit beams seems to restore this important property, enabling higher acquisition rates without loss of image quality.     

On attempts to measure the tenderness of Longissimus Dorsi muscles using fluorescence emission spectra

Autofluorescence spectra have been obtained on beef longissimus dorsi muscles (n=151), and the spectra regressed against Warner-Bratzler (WB) peak values. The spectra obtained depended on the method used, and it is suggested that the difference is related to the use of two different types of Xenon lamps (a pulsed versus a continuous light source) and the inherent kinetic differences in the collection of the fluorochromes' emitted light. Poor to good (R=0.45-0.84) correlations between WB peak values and the emission spectra were obtained. This relationship is established using chemical information originating largely from collagens. Minor differences in predictability were observed using either excitation wavelengths 332 or 380?nm. The emission wavelengths containing the most relevant information about WB peak values were between 360 and 500 nm. Wavelengths around 375 nm, excitation 332 nm, were in particular important and were related to a component in the perimysial tissue, most likely being present in collagen I or III. Excitation at 380?nm revealed the wavelength range 460-480?nm as important presumed due to collagens in the perimysium. An experiment, simulating industrial routines, using 45 samples collected at the slaughterhouse two days post mortem, was carried out. However, for those samples no model was observed between the emission spectra and WB peak values. Only when some samples having very low (相似文献   

Influence of high-pressure–low-temperature treatments on fruit and vegetable quality related enzymes

Recently, high-pressure–low-temperature (HP-LT) treatments, succeeding a regular freezing unit operation, have been shown to inactivate micro-organisms. In this study, we have evaluated the influence of these treatments on the inactivation of quality-related enzymes. The effect of different pressure/temperature combinations (range 0.1–500 MPa/20 to −26 °C) on the activity of pectinmethylesterase, polygalacturonase, lipoxygenase, peroxidase and polyphenoloxidase in model systems, crude extracts and real-food systems was investigated.Present results show that under these HP-LT processing conditions, no or limited enzyme inactivation is obtained for all enzyme systems studied, except for lipoxygenase which can be completely inactivated at high pressure in combination with low temperature. These data suggest that HP-LT treatments, although inactivating micro-organisms, fail to inactivate most food quality related enzymes. Therefore, a blanching unit operation (e.g. a conventional thermal blanching process prior to freezing) is required to prevent enzyme related quality degradation during frozen storage and cannot be replaced by an integrated freezing-HP-LT treatment.     

Non-destructive determination of fat,moisture and protein in salmon fillets by use of near-infrared diffuse spectroscopy

Near infrared (NIR) diffuse spectroscopy was used to determine the fat, moisture and protein contents in whole and ground farmed atlantic salmon fillets. A remote fibre-optic probe was used for NIR measurements on 50 whole salmon fillets. The constituent ranges were: 91-205 g kg^?1 fat, 599-709g kg^?1 moisture and 186-209 g kg^?1 protein. Principal component regression resulted in the following prediction errors for ground salmon fillets, expressed as root mean square error of cross validation: 6.6 g kg-1 fat, 3.8 g kg^?1 moisture and 2.0 g kg^?1 protein. The corresponding prediction errors for non-destructive measurements on whole salmon fillets were 10.8 g kg^?1 fat, 8.5 g kg^?1 moisture and 3.7 g kg^?1 protein. Regression models using the 760-1100 m range gave lower prediction errors than models using the 1100-2500 mm or 760-2500 nm ranges. The results show that fibre-optic probe NIR instruments are suited to determine fat and moisture in whole salmon fillets non-destructively.     

'Lifestyle' and cancer rates in former East and West Germany: the possible contribution of diagnostic radiation exposures

Breast and prostatic cancer as well as leukaemia in childhood have remarkably increased over some decades in the Federal Republic of Germany as well as in several other highly developed industrial nations. Such increase was much less or not observable in East Germany between 1960 and 1989 where diagnostic exposures were applied to a lesser extent. Low-level radiation can cause these diseases and the difference of cancer rates gives rise to renewed evaluation of current risk estimates. Risk factors for radiation-induced childhood leukaemia and breast cancer are derived from the literature, considering a higher relative biological effectiveness of diagnostic X rays in comparison to the A-bomb gamma rays in Hiroshima and Nagasaki. The prostate is not considered as radiation sensitive by the ICRP. But following a variety of low-level findings in the last two decades it was shown by Myles et al. in the UK that prostatic cancer is inducible by diagnostic X-ray procedures. From their study in men below the age of 60, a doubling dose of about 20 mSv can be estimated. Medical exposures of the considered tissues are taken from published data for East and West Germany. The difference in breast cancer mortality can be explained by diagnostic exposures. The contribution of these to prostatic cancer and childhood leukaemia must be regarded as relevant in current incidences. Reduction of diagnostic exposures would be an important measure for preventing several prominent cancer diseases.     

Corrections for diffuse irradiance measured with shadowbands

The reduction of measured diffuse irradiance due to the use of a shadowband is evaluated. For cloudless sky, an exact mathematical model was developed. Measurements throughout the year confirm the model results. The values are close to the semiempirical model developed by Drummond only during noon hours. Towards morning and afternoon a contribution from reflected direct solar irradiance from inside the shadowband reduces the loss and, at very low sun angle, can even provide a gain in the measured diffuse irradiance. The albedo of the inner band surface is of importance for the amount of this gain.During overcast sky the loss of measured diffuse irradiance varies with the season: During the winter months when only a small section of the sky is obstructed by band, 3 per cent are lost, during summer this value is between 8 and 10 per cent.     

Dimethyl sulfide removal from synthetic waste gas using a flat poly(dimethylsiloxane)-coated composite membrane bioreactor

The reduction of volatile organic sulfur emissions should be completely as they cause odor nuisance, even when they are emitted in very small amounts. In general, biofilters are applied for odor reduction, but their operational control is limited. A new biotechnique for the treatment of complex emissions is the use of membranes integrated within bioreactors (MBRs). In this study, the reactor performance of MBRs for removal of dimethyl sulfide (DMS) as a model compound is presented. Composite membranes with a poly(dimethylsiloxane) (PDMS)-coating layer were used. The MBRs were inoculated with the sulfur-degrading culture Hyphomicrobium VS or a suspension of Hyphomicrobium VS, ammonium-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB) to colonize the PDMS-coating layer. Although inoculation with AOB and NOB might give rise to competition for space on the membrane, their presence in the MBRs appeared to be positive as they co-oxidize DMS. Dimethyl sulfide elimination depended on the inoculum type, DMS inlet concentration, gas residence time, and membrane polymer. For equal loading rates, the elimination capacity (EC) increased at larger gas residence times and inlet concentrations. The maximum EC obtained with the MBRs was 4.8 kg of DMS x m(-3) x d(-1). This value is higher than any reported figure for biofilters and biotrickling filters.