Evidence for quantum confinement effects in CdSe/ZnSe multilayer thin films prepared by the physical vapor deposition method

CdSe/ZnSe heterostructure multilayer thin films were prepared with different sublayer thicknesses of CdSe using the physical vapor deposition method. X-ray diffraction studies were used to calculate the average size of the particles and confirmed the (1 1 1) plane of ZnSe. Due to the stacking of alternate CdSe and ZnSe layers, stress was created in the multilayer systems. This results in quantum size effects. Experimentally measured energy values from (hν) vs. (αhν)² dependence confirm the presence of spin–orbit split in the valence band of CdSe. The calculated band gap energies are greater than that of bulk CdSe. Crystallite sizes (12–4 nm) were calculated based on the predictions of the effective mass approximation model (i.e. Brus model). Results show that the diameters of crystallites are smaller than the Bohr exciton diameter (11.2 nm) of CdSe. Upon particle size decrease, the photoluminescence peak is shifted from the green region to the blue region. Analysis shows that the sublayer thickness of CdSe material changes the properties of CdSe/ZnSe multilayer systems.     

Cosmopolitanism, geographical imaginaries and belonging in North London

Cosmopolitanism has been described as the cultural habitus of globalisation. It is therefore, albeit defined somewhat loosely, often associated with ethnically diverse, global cities. This paper considers the extent to which London engenders cosmopolitan values amongst its residents. It draws on survey data from the LOCAL MULTIDEM study of minorities' political participation to address these themes. The analysis examines perceptions of respect, belonging and geographical imaginaries - amongst established minorities and the ethnic majority - in north London. It is argued that cosmopolitan ethics are transformative and dialectical and, critically, cannot remain the preserve of the privileged in multi-ethnic neighbourhoods. The analysis presented demonstrates that a sense of belonging and cosmopolitan imaginaries are not evenly accessed by different ethnic groups; notably, that Bangladeshi Londoners who are born and bred in the city are less likely to appropriate these discourses than Caribbean, Indian or White residents.     

Effect of Different Binders on the Physico-Chemical, Textural, Histological, and Sensory Qualities of Retort Pouched Buffalo Meat Nuggets

ABSTRACT: The functional properties of 4 binders, namely corn starch, wheat semolina, wheat flour, and tapioca starches, were evaluated to improve the quality of buffalo meat nuggets processed in retort pouches at F₀ 12.13. Incorporation of corn starch in buffalo meat nuggets produced more stable emulsion than other binders used. Product yield, drip loss, and pH did not vary significantly between the products with different binders. Shear force value was significantly higher for product with corn starch (0.42 ± 0.0 Kg/cm³) followed by refined wheat flour (0.36 ± 0.010 Kg/cm³), tapioca starch (0.32 ± 0.010 Kg/cm³), and wheat semolina (0.32 ± 0.010 Kg/cm³). Type of binder used had no significant effect on frying loss, moisture, and protein content of the product. However, fat content was higher in products with corn starch when compared to products with other binders. Texture profile indicated that products made with corn starch (22.17 ± 2.55 N) and refined wheat flour (21.50 ± 0.75 N) contributed firmer texture to the product. Corn starch contributed greater chewiness (83.8 ± 12.51) to the products resulting in higher sensory scores for texture and overall acceptability. Products containing corn starch showed higher sensory scores for all attributes in comparison to products with other binders. Panelists preferred products containing different binders in the order of corn starch (7.23 ± 0.09) > refined wheat flour (6.48 ± 0.13) > tapioca starch (6.45 ± 0.14) > wheat semolina (6.35 ± 0.13) based on sensory scores. Histological studies indicated that products with corn starch showed dense protein matrix, uniform fat globules, and less number of vacuoles when compared to products made with other binders. The results indicated that corn flour is the better cereal binder for developing buffalo meat nuggets when compared to all other binders based on physico-chemical and sensory attributes.     

Structural,luminescence and magnetic properties of Mn doped ZnO thin films using spin coating technique

Manganese doped zinc oxide (ZnO) thin films were synthesized for various wt% doping of Mn using sol–gel spin coating technique. The effects of Mn doping on the structural, morphological, compositional, photoluminescence (PL) and magnetic behaviour of ZnO thin films were investigated. Although, Mn doping did not change the lattice constants of the films, the texture coefficient is found to be improved for the films having higher percentage of Mn doping. PL studies reveal that as doping concentration of Mn increases, the intensity of emission peaks corresponding to violet and blue colour increases and the peak position shifts slightly. The saturated magnetic moments are found to decrease with the increase in Mn doping and the reason for such behavior is discussed.     

Determination of biodegradable dissolved organic carbon using entrapped mixed microbial cells

Several methods for determining biodegradable dissolved organic carbon (BDOC) in water have been developed within the last two decades. However, the problem with most of these methods is the length of time required for the start-up (colonization) and/or determination from days to weeks. In this study, a simple and rapid continuous bioreactor procedure using immobilized cells was developed for BDOC determination. In the first stage of the development, the bioreactors were aerated to ensure that dissolved oxygen was not rate limiting. However, BDOC results obtained from the aerated bioreactors suffered from a large error caused by the release of background dissolved organic carbon (DOC). As a consequence, a different bioreactor scheme, in which the feed (sample) instead of the bioreactor was aerated, was tested. Results show that the feed aerated (FA) bioreactor is a better tool for BDOC determination especially for waters with low initial organic concentrations because of less background DOC released by the immobilized cell systems. Using the FA bioreactor, the accurate and reproducible measurement of BDOC can be achieved within a hydraulic retention time of 3 h, and no start-up period is required.