We demonstrate stable three-dimensional (3D) single-beam optical trapping of gold nanoparticles with diameters between 18 and 254 nm. Three-dimensional power spectral analysis reveals that, for nanoparticles with diameters less than 100 nm, the trap stiffness is proportional to the volume of the particle. For larger particles, the trap stiffness still increases with size, however, less steeply. Finally, we provide numbers for the largest forces exertable on gold nanoparticles.

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Calcium-fortified soy milk (200 mg/100g) was formulated by adding to water (85-90ЊC) full-fat soy flour (10%), sucrose (2.75%) and soy protein isolate (2.25%). Following homogenization, the blend was twice clarified and pasteurized at 65ЊC/30 min before refrigeration. Samples of the soy milk (45ЊC) were adjusted to pH 8 before adding calcium lactogluconate (1.55%) and varying amounts of sodium hexametaphosphate or potassium citrate. Samples with 1.25% potassium citrate had the best heat stability. For successful calcium fortification, it is recommended to maintain a calcium-to-protein ratio Ͻ 38 mg/g and to use an appropriate sequestering agent at a molar ratio of 0.8/mole calcium.

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In the process of isolating sialic acid from bovine isoelectric casein a hydrolytic product (CBF) was obtained, possessing growth promoting activity for Bifidobacterium bifidum var. pennsylvanicus. Growth was measured turbidimetrically by addition of CBF (250 ppm) to ATCC Medium 76. Stimulation by CBF was comparable to that obtained with N-acetylglucosamine. Whole casein, sialic acid-free casein and k-casein failed -to stimulate the growth of -the organism to the level achieved with CBI? The CBF fraction contained 0.15% nhosohorus. 7% free lactose and various peptides. No sialic acid or other amino sugars were detected. On the basis of phosphorus content and amino acid analysis it was concluded that CBF was likely a degradation product of k-casein.

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