Pt@Fe 2 O 3 core−shell nanoparticles have been made using a sequential synthetic method. Platinum nanoparticles were synthesized via reduction of platinum acetylacetonate in octyl ether, and layers of iron oxide were subsequently deposited on the surface of Pt nanoparticles through thermal decomposition of iron pentacarbonyl. The core−shell nanoparticles were characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoemission spectroscopy. Thickness of the shell can be controlled by changing concentrations of the reactants and the reaction conditions. These Pt@Fe 2 O 3 core−shell nanoparticles could have potential applications in catalysis and as precursors for making property-tunable magnetic nanoparticles, thin films, and nanocomposites.

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Little is known regarding the physiological rôle of oviduct fluid on ova and spermatozoa in the reproductive tract. VanDemark (1958) and Bishop (1961) suggested that luminal fluids may be an important transport and nutrient medium for the gametes; others felt that oviduct secretions influenced sperm activity (Olds & VanDemark, 1957a) or aided the capacitation process (Austin, 1951: Chang, 1951. Oviduct fluid has been collected from several species by ligation of portions of the genital tract (Blandau, Jensen & Rumery, 1958), flushing portions of the tract (Heap, 1962), expressing the contents of tracts after slaughter (Olds & VanDemark, 1957b), and cannulation of portions of the tract in living animals (Clewe & Mastroianni, 1960;Restall, 1966). To our knowledge, oviduct secretion has never been continuously collected throughout the oestrous cycle and an attempt was made to determine whether the volume, protein content, or glucose content of oviduct fluid varied during the oestrous cycle.Cows of small size were chosen for this experiment because the reproductive tract was more accessible at surgery. Surgery was performed at mid-cycle, either under local anaesthesia (infusion of Xylocaine), or general anaesthesia (Equithesin). In both cases, an incision was made in the flank area and the uterus and oviduct were drawn as close as possible to the opening. The ovarian end of the oviduct was located and one end of a 60-cm long silastic cannula (ID 0-10 cm, OD 0-20 cm) was inserted to a depth of 15 mm. Two collars were placed on the end of the cannula, which was held in place by two Supramid sutures ; the uterine end of the oviduct was ligated with one Supramid suture to prevent flow of oviduct fluid into the uterus. A small amount of air was injec¬ ted into the cannula, which was considered patent if the oviduct distended. The cannula was then brought out through the incision and the animal was given 1 million units of procaine penicillin in oil daily for 4 days.The collection device was contained in a 3-x4-in. aluminium cassette attached to the animal with four sutures. The cannula was inserted through a plastic disc at the surface of the skin and several sutures tied around it to prevent the cannula from slipping through the plastic disc and into the body cavity. The cannula entered a plastic vial within the cassette and the vial was changed daily. The fluid was left in the vial and frozen ; the volumes were later measured with a 1-ml tuberculin syringe. For analysis, the fluid was pooled on a 4-day basis with respect to oestrus, e.g. a sample labelled +1 would include fluid collected on the 1st day of oestrus 549