Acceptability and Digestibility of Emulsions in a Rat Model: Effects of Solid Fat Content and Lipid Type

The present study sought to determine if alterations in the chemical nature and form of fat in food would reduce digestibility while maintaining acceptability in rats. Oil-in-water emulsions (d < 1 μm) were prepared with either liquid palm oil, solid hydrogenated palm oil or solid docosane, all stabilized with sodium caseinate. The emulsions were incorporated into a fat-free rodent feed, and each offered over 5 days to separate cohorts of 12 male Sprague–Dawley rats housed in metabolic cages. The feed formulated with solid hydrogenated palm oil was significantly less acceptable than the feeds containing either liquid palm oil or docosane (feed intake 4.9, 26.6 and 32.1 g/animal/day respectively). The proportion of the fat retained (i.e. absorbed) was significantly less in the animals consuming the feed formulated with solid docosane than in the animals consuming either the liquid or solid palm oil (retention 8.7, 99.6, and 97.2%, respectively). The appearance of the feces from the rats fed docosane was different from the rats fed the triacylglycerol samples and thermal analysis revealed many of the solid alkane droplets had not coalesced during passage through the rat’s digestive system. These results indicate that indigestible fats can be packaged into food in a manner that does not compromise the acceptability of the product, and does not produce any apparent intestinal distress.     

Ultrasonic characterization of lactose crystallization in gelatin gels

Ultrasonic velocity and attenuation measurements (2.25 MHz center frequency) were used to follow bulk crystallization of lactose (43% and 46%) from gelatin (1.5% and 3%) gels at 25 °C, and compared to turbidity (500 nm) and isothermal calorimetric measurements. Ultrasonic velocity decreased slightly (approximately 0.5%) during crystallization while ultrasonic attenuation was low in the absence of lactose crystals and increased progressively during crystallization. The lag time before the onset of crystallization decreased and the maximum rate of increase in attenuation during crystallization increased with increasing lactose supersaturation but was not affected by gelatin concentration (P < 0.05). Similar results were seen in turbidity and isothermal calorimetric measurements. Ultrasonic attenuation measurements have the potential to measure crystallization kinetics in complex food matrices and to be applied on-line. Practical Application: Many foods contain crystals that affect their taste and texture (for example, lactose crystals can give a grainy defect in ice cream). The formation of crystals is often hard to predict so methods to measure the development of crystals inside real foods are useful. In this study, we show that as lactose crystallizes in a gelatin gel the ultrasonic attenuation--capacity to absorb sound--increases and can be related to the amount of crystals present. Ultrasound is easier to apply in real food processing than the existing methodologies.     

The laser strain gauge: micro machining of diffraction gratings using an Excimer laser

The laser strain gauge is a recently developed instrument for the single point measurement of surface strain to a resolution of 1 μm. It measures the deformation of a diffraction grating adhered to or etched into the surface of various substrates. In comparison with a conventional electrical resistance strain gauge the new gauge offers greater thermal stability and avoids the inconvenience of electrical connections. When gratings are etched directly into the surface of a component absolute strain measurements over its lifetime are possible.
High frequency (1000 lines/mm) diffraction gratings can be etched into the surface of various substrates including carbon steels, polymers and ceramics using an Excimer laser. This paper describes the optical beam delivery system necessary for this application and demonstrates the feasibility of this exciting new technique.     

Early macular dysfunction detected by focal electroretinographic recording in non-insulin-dependent diabetics without retinopathy

The focal electroretinogram, which measures the functional integrity of the distal retina of the macula, was recorded with a hand-held stimulator-ophthalmoscope in 26 eyes from patients with non-insulin-dependent diabetes mellitus with normal fundus photography, and in 52 control eyes of similar age range. Implicit time and amplitude of the responses were studied as a function of the age, glycemic control through glycosylated hemoglobin measurement and duration of diabetes. Implicit time and amplitude were significantly delayed (F=5.05, p=0.028) and reduced (F=11.26, p=0.013) in diabetic patients without diabetic retinopathy compared to control subjects. Moreover, there was a significant relationship between the implicit time (r=0.57, p=0.002) and amplitude (r=-0.65, p=0.0004) with the duration of diabetes but not with hemoglobin Alc. These results strongly suggest an early macular dysfunction in non-insulin-dependent diabetes mellitus before the appearance of diabetic retinopathy.     

Adaptive-mutation compact genetic algorithm for dynamic environments

In recent years, the interest in studying nature-inspired optimization algorithms for dynamic optimization problems (DOPs) has been increasing constantly due to its importance in real-world applications. Several techniques such as hyperselection, change prediction, hypermutation and many more have been developed to address DOPs. Among these techniques, the hypermutation scheme has proved beneficial for addressing DOPs, but requires that the mutation factors be picked a priori and this is one of the limitations of the hypermutation scheme. This paper investigates variants of the recently proposed adaptive-mutation compact genetic algorithm (amcGA). The amcGA is made up of a change detection scheme and mutation schemes, where the degree of change regulates the probability of mutation (i.e. the probability of mutation is directly proportional to the degree of change). This paper also presents a change trend scheme for the amcGA so as to boost its performance whenever a change occurs. Experimental results show that the change trend and mutation schemes have an impact on the performance of the amcGA in dynamic environment and also indicate that the effect of the schemes depends on the dynamics of the environment as well as the dynamic problem being considered.     

Particle image velocimetry: image labeling by use of adaptive optics to modify the point-spread function

A simple method of labeling the first- and second-exposure images of a particle-image-velocimetry recording is discussed. One achieves this method by changing the transfer characteristics of the recording optics between exposures by inserting a rotating optic into the iris plane of the camera objective. Spatial filtering can then be used to address the images recorded by each exposure independently, permitting cross-correlation analysis to be implemented. Two practical systems using either an aperture plate or a phase plate are demonstrated, and we show that the phase plate is significantly more light efficient. Finally, the feasibility of image labeling high-speed flows using electro-optic devices is discussed.     

Improvement of RNA-SIP by pyrosequencing to identify putative 4-n-nonylphenol degraders in activated sludge

Nonylphenols (NP) have estrogenic potential because of their phenolic ring, but the organisms involved in the degradation of this alkylated phenol remain unidentified. Using 16S ribosomal RNA (rRNA)-based stable isotope probing (SIP) and a new method based on pyrosequencing, we identified the bacteria involved in the degradation of the aromatic ring of [U-ring-¹³C] 4-n-NP in aerobic sludge. The first order degradation rate of 4-n-NP was 5.5 d⁻¹. Single strand conformation polymorphism of density-separated labeled and unlabeled 16S rRNA showed significant differences and enabled selection of four representative fractions for pyrosequencing. Nineteen phylotypes showed a significant enrichment in the heavy fraction in the labeled pulse. The relative abundances of these phylotypes were combined with the RNA concentration of each fraction to yield a simple model of the distribution of each phylotype across the gradient. This model was used to estimate the percentage of labeling for each phylotype. The sequences showing the highest labeling (11%) were closely related to Afipia sp. but represented only 2 % of the RNA in the heavy fraction of the labeled pulse. The sequences representing the largest proportion of the RNA in the heavy fraction were related to Propionibacterium acnes and Frateuria aurantia, which are known to possess enzymes for phenol degradation. The model shows that despite Afipia having the highest ¹³C enrichment, other species encoding phenol degradation pathways are responsible for more ¹³C incorporation. Last, we showed that some species represent 12% of the total RNA but contain only 1% ¹³C above natural abundance.     

Simultaneous wavenumber measurement and coherence detection using temporal phase unwrapping

Wavelength scanning interferometry and swept-source optical coherence tomography require accurate measurement of time-varying laser wavenumber changes. We describe here a method based on recording interferograms of multiple wedges to provide simultaneously high wavenumber resolution and immunity to the ambiguities caused by large wavenumber jumps. All the data required to compute a wavenumber shift are provided in a single image, thereby allowing dynamic wavenumber monitoring. In addition, loss of coherence of the laser light is detected automatically. The paper gives details of the analysis algorithms that are based on phase detection by a two-dimensional Fourier transform method followed by temporal phase unwrapping and correction for optical dispersion in the wedges. A simple but robust method to determine the wedge thicknesses, which allows the use of low-cost optical components, is also described. The method is illustrated with experimental data from a Ti:sapphire tunable laser, including independent wavenumber measurements with a commercial wavemeter. A root mean square (rms) difference in measured wavenumber shift between the two of ~4 m?1 has been achieved, equivalent to an rms wavelength shift error of ~0.4 pm.     

Monitoring Molecular Diffusion of Sucrose in Xanthan Solutions using Ultrasonic Velocity Measurements

Measurements of the velocity of ultrasound through a sample as a function of diffusion distance were used to study molecular diffusion of sugars through biopolymer solutions. A1 wt% xanthan solution was prepared which consisted of a lower layer containing no sucrose, and an upper layer containing sucrose (10, 20, 30, or 40 wt%). The velocity of ultrasound through the biopolymer solutions was measured as a function of sample height and time, and then converted into sucrose concentration-distance profiles using an empirical calibration curve. The translational diffusion coefficient of the sucrose in the upper and lower layers was determined by fitting the experimental data to a Fickian diffusion model. The measured diffusion coefficients were in reasonable agreement with published values for sucrose in aqueous solutions in the absence of xanthan, which suggests the biopolymer had little influence on molecular diffusion.