Quantitative Study of Growth of Some Dairy Psychrophiles

Summary and Conclusions: Samples of pasteurized skim milk were steamed for 25 minutes at approximately 100° C. and inoculated with pure cultures of Pseudomonas fluorescens, A and B, at different levels, Pseudomonas fragi, Brevibacterium lipolyticum. The fifth culture was the normal flora of commercially pasteurized skim milk treated as a pure culture. All samples were stored at 4° C. Bacterial growth was determined using agar plates incubated at 25° C. for 3 days. The generation time was calculated for all cultures which ranged from 5.55 hours for Pseudomonas fragi to 11.24 hours for Brevibacterium lipolyticum. The generation time was found the same (7.22 hours) for Pseudomonas fluorescens cultures A and B regardless of differences in inoculum size for the two cultures. In the pure cultures, bacterial count after 7 days of storage was the highest for Pseudomonas fragi, 3.0 x 107, and the lowest for Brevibacterium lipolyticum, 1.9 x 105 cells per ml. However, the mixed flora culture obtained a slightly lower count, 1.7 x 105 cells per ml. The lag phases for the pure cultures studied ranged from 1 day for Pseudomonas fragi to 3 days for both cultures of Pseudomonas fiuorescens. The mixed flora culture showed still a longer lag phase of 4.2 days. Of all cultures studied, Pseudomonas fragi was found to be the most actively growing culture. It had the shortest generation time, the highest counts after 7 days of storage, and the shortest lag phase

Development and construction of rotating polarizer analyzer ellipsometer

A detailed mathematical derivation and an experimental characterization of one to two ratio rotating polarizer analyzer ellipsometer (RPAE) are presented. The alignment, calibration, and testing of reference samples are also discussed. The optical properties of some known materials obtained by the proposed ellipsometer will be shown and compared to accepted values. Moreover, the constructed ellipsometer will be tested using two ellipsometry standards with different thicknesses

Theoretical spectroscopic scan of the sensitivity of asymmetric slab waveguide sensors

An extensive theoretical analysis is carried out to investigate the variation of the sensitivity of optical slab waveguide sensors with the wavelength of the guided wave. We consider a three-layer waveguide as an optical sensor. The sensitivity for both polarizations of light: s-polarized light (TE) and p-polarized light (TM), is derived using the characteristic equation of the structure. The dispersion of the materials is taken into account to study the sensitivity spectroscopic scan over the near IR-range from 1.2–2 µm. It is found that an optimum wavelength exists for each guiding layer thickness and this optimum value increases linearly with the thickness of the guiding layer

Comparing optical sensing using slab waveguides and total internal reflection ellipsometry

The sensitivity of the effective refractive index of slab waveguide sensors to variations in the refractive index of the cladding is compared to that of the ellipsometric parameters. The changes of the effective refractive index of a waveguide and the ellipsometric parameter\Delta, due to the index change of the cladding, were derived and plotted as a function of the guiding layer thickness and with the index of the cladding. It is found that these changes almost have the same overall feature but the ellipsometric parameters showed considerable higher sensitivity than the effective index of the conventional waveguide optical sensors

NEURAL NETWORKING OF INFILLED RC LOW-RISE SERVICE BUILDINGS

Artificial neural networks (ANNs) are one of the most research areas that attracts the attention of experts of various scientific areas. Recent research activities regarding ANNs indicated that this method is a powerful tool to solve complicated problems in engineering fields.In this paper, ANNs were utilized to predict the lateral behavior of school buildings in Egypt. For this, reinforced concrete (RC) frames representing common school buildings with different characteristics were analyzed using nonlinear dynamic pushover analysis to obtain their capacity curves, failure loads and displacements. Parameters included number of stories, location and dimensions of the frames, distribution of masonry infill panels, and properties of concrete and reinforcement. Obtained data were used to train several ANN models with different topologies and learning algorithms. The most representative ANN was used to obtain more insight into the behavior of school building frames with different parameters

Rotating polarizer, compensator, and analyzer ellipsometry

In this paper we propose theoretically a set of ellipsometric configurations using a rotating polarizer, compensator, and analyzer at a speed ratio of N 1 ω: N 2 ω: N 3 ω. Different ellipsometric configurations can be obtained by giving different integral values to N 1, N 2, and N 3. All configurations are applied to bulk c-Si and GaAs to calculate the real and imaginary parts of the refractive index of the samples. The accuracies of all ellipsometric configurations are investigated in the presence of a hypothetical noise and with small misalignments of the optical elements. Moreover, the uncertainties in the ellipsometric parameters as functions of the uncertainties of the Fourier coefficients are studied. The comparison among different configurations reveals that the rotating compensator—analyzer configuration corresponds to the minimum error in the calculated optical parameters

Optical Parameters of Varies Thickness of Bismuth (Iii) Iodide Thin Films for Photovoltaic and Nonlinear Applications

We report in varies thickness of BiI3 thin films by thermal evaporation techniques onto glass substrate. The films were strongly oriented along the (113) plane. The structural parameters of these films (crystallite size and lattice strain) were determined using (XRD) pattern. The thicknesses and refractive indices of the films were considered using Swanepoels method. The band gap was determined in terms of T and R spectrum in the UV-region of the absorption. The possible optical transitions of all films are found to be allowed direct transition with energy gap fluctuate bout 1.96 ± 2% eV. Dielectric constant, volume-energy-loss function (VELF) and surface-energy-loss function (SELF) for as deposited films were discussed in terms of film thickness rising. The change in optical parameters have been interpreted in terms of the change in microstructure parameters. BiI3 is recommended for photovoltaics and nonlinear optics because of its higher absorption coefficient, dielectric constant, and fair band gap

Elemental Analysis and Natural Radioactivity Levels of Clay by Gamma Ray Spectrometer and Instrumental Neutron Activation Analysis

Due to increased global demand for clay, the present work involves the use of INAA for elemental analysis and pollutants concentration in clay. The samples were collected from Aswan in South Egypt. The samples were irradiated using the thermal neutrons "at the TRIGA Mainz research reactor" and at a neutron flux "of 7 × 10 n/cm s". Twenty-six elements quantitatively and qualitatively were specified for the first time upon studying the samples. The elements determined are U, Th, Ta, Hf, Lu, Eu, Ce, Ba, Sn, Nb, Rb, Zn, Co, Fe, Cr, Sc, Sm, La, Yb, As, Ga, K, Mn, Na, Ti, and Mg. The concentrations of natural radionuclides 232 Th, 226 Ra, and 40 K were also calculated. Based on these concentrations, to estimate the exposure risk for using clay as raw materials in building materials, the radiation hazard indices such as radium equivalent activities, effective doses rate, and the external hazard indices have been computed. The obtained results were compared with analogous studies carried out in other countries and with the UNSCEAR reports