Fracture Induced in Al2O3 Bicrystals by Anisotropic Thermal Expansion

Bicrystals of Al₂O₃ were fabricated to study the effects of thermal expansion anisotropy on fracture in a model system containing one grain boundary. Fractures occurred perpendicular to the directions of maximum tensile stress in bicrystals with thermal expansion coefficient differences as low as 0.31×10⁻⁶⁰C⁻¹ and originated at the boundary, probably in areas of high residual stress associated with pores. Numerical stress analysis of two-dimensional model bicrystal configurations showed that stresses induced by thermal expansion anisotropy are maximal in a region localized along the bicrystal boundary.     

SOLAR TUNNEL DRYING OF TURMERIC (CURCUMA LONGA LINN. SYN. C. DOMESTICA VAL.) FOR QUALITY IMPROVEMENT

Turmeric is one of the most ancient medicinal spices of the world. As its homeland, India acts as the largest producer, exporter and consumer of turmeric. The value of turmeric is due to its color and flavor, which is being given by curcumin, volatile oil and oleoresin. The end quality of turmeric is very much dependent on its post-harvest methods. Traditionally, open sun drying is the chief method adopted for processing. In the present investigation, freshly harvested turmeric rhizomes were collected from 30 stations and drying experiments were conducted by adopting three methods: (1) solar tunnel drying; (2) conventional drying; and (3) commercial drying. Various pre-drying and post-drying treatments were conducted. The results proved that conventional processing could maintain the intrinsic quality up to a certain level, but extrinsic quality could not be achieved. Solar tunnel drying method is an effective alternative to traditional open sun drying, where retention of curcumin, volatile oil and oleoresin was high, with less drying time. The study also disclosed the importance of pre-drying and post-drying treatments and hygienic practices to be adopted during processing.

PRACTICAL APPLICATIONS

Solar tunnel dryer can be used to process most of the spices, vegetables, fruits and other perishable crops with maximum retention of intrinsic quality and for better shelf life. Substantial reduction of drying time and physical quality improvement with regard to international quality standards are the other advantages.     

REMOVAL OF SULFAMETHAZINE FROM ARTIFICIALLY CONTAMINATED MILK BY ULTRAFILTRATION

The effect of discontinuous diafiltration (DD) on removal of sulfamethazine (SMZ) from raw whole and homogenized milk was studied. Milk was artificially contaminated with concentrations of SMZ varying from 20 to 90 μg/L. A hollow-fiber membrane with a molecular weight cut-off of 10,000 daltons was used for all experimental runs at 55C. The removal pattern of SMZ was influenced (P<0.05) by both the initial concentration and the homogenization process. Homogenization increased the removal of SMZ from milk. The DD process resulted in concentrates with residual levels of SMZ <10 μg/L (FDA action level). SMZ was not detected in reconstituted retentates resulting from milk originally up to 30 μg/L.     

Methods to calibrate and scale axial distances in confocal microscopy as a function of refractive index

Accurate distance measurement in 3D confocal microscopy is important for quantitative analysis, volume visualization and image restoration. However, axial distances can be distorted by both the point spread function (PSF) and by a refractive‐index mismatch between the sample and immersion liquid, which are difficult to separate. Additionally, accurate calibration of the axial distances in confocal microscopy remains cumbersome, although several high‐end methods exist. In this paper we present two methods to calibrate axial distances in 3D confocal microscopy that are both accurate and easily implemented. With these methods, we measured axial scaling factors as a function of refractive‐index mismatch for high‐aperture confocal microscopy imaging. We found that our scaling factors are almost completely linearly dependent on refractive index and that they were in good agreement with theoretical predictions that take the full vectorial properties of light into account. There was however a strong deviation with the theoretical predictions using (high‐angle) geometrical optics, which predict much lower scaling factors. As an illustration, we measured the PSF of a correctly calibrated point‐scanning confocal microscope and showed that a nearly index‐matched, micron‐sized spherical object is still significantly elongated due to this PSF, which signifies that care has to be taken when determining axial calibration or axial scaling using such particles.