Showing papers by "All Saints' College published in 2013"

Effect of borosilicate glasses on the microwave dielectric properties of ZnO–Nb 2 O 5 –Ta 2 O 5 system

Abstract: (1 − y)[0.5ZnNb2O6–0.5Zn3Nb2O8]–yZnTa2O6 with y = 0.91 (ZNT) ceramic have been prepared by conventional solid state ceramic route. The effect of glass additives on the microstructure, densification, and microwave dielectric properties of the ZNT ceramic for low temperature co-fired ceramic applications was investigated. Different weight percentages of quenched glass such as ZnO–B2O3–SiO2, BaO–B2O3–SiO2, LiO–B2O3–SiO2 and MgO–B2O3–SiO2 were added to ZNT powder. The crystal structure of the ceramic–glass composites was studied by X-ray diffraction and microstructure by scanning electron microscopy. The microwave dielectric properties such as relative permittivity (er), quality factor (Quxf) and co-efficient of temperature variation of resonant frequency (τf) of the ceramics have been measured in the frequency range 4–6 GHz. The 5 wt% ZnO–B2O3–SiO2 added ZNT ceramic sintered at 900 °C showed: er = 28.1, Quxf = 32820 GHz (at 4.92 GHz), and τf = −7.7 ppm/oC respectively.

Estimation of Lycopene Content in Different Tomato Varieties and its Commercial Products

Abstract: the edible, typically red fruits that it bears. This domesticated fruit was first introduced into Europe in 1554 after the Spanish colonization of the Americas (Gould, 1992).It is used in diverse ways, including raw in salads and processed into ketchup or tomato soup. Tomatoes are acidic, thereby making them easy to preserve in home canning whole, in pieces, as tomato sauce or paste. Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart, among other organs. Tomatoes have been traditionally credited as rich sources of carotenoids and vitamins, particularly beta-carotene, pro-vitamin A, ascorbic acid, and vitamin (Hanson et al., 2004). In recent years, another important carotenoid in tomatoes, lycopene, has received considerable attention. Lycopene is responsible for the red color in tomatoes, watermelons, and pink grapefruits (Rao and Agarwai, 2000). Lycopene (from the new Latin word lycopersicum, referring to the tomato species) is a bright red carotene and carotenoid pigment and photochemical found in tomatoes and other red fruits and vegetables, such as red carrots, red bell peppers, watermelons, gac and papayas (but not strawberries or cherries). Although lycopene is chemically a carotene, it has no vitamin A activity. Lycopene is a bioactive carotenoid present in many fruits and vegetables. Tomatoes constitute the major dietary source of lycopene. Recent evidence shows lycopene to be associated with several health benefits. However, very little information is available about the stability of lycopene and its bioavailability. Because tomatoes undergo extensive processing and storage before consumption, recent studies (Delgado-Vargas and Paredes-Lopez, 2003) evaluated the stability, isomeric form, bioavailability, and in vivo antioxidant properties of lycopene. Total lycopene and isomers were measured by spectrophotometry and high-performance liquid chromatography, respectively. The antioxidant capability of lycopene has led to promising results in decreasing the risk of some illnesses and cancers. Several studies showed that lycopene is able to prevent the oxidation of low-density lipoprotein (LDL), which causes the atherogenic process and heart disease (Delgado-Vargas and ParedesLopez, 2003). In fresh tomatoes, the content of lycopene