This work is concerned with theoretical study of hydrodynamic journal bearings lubricated with ferrofluids exhibiting non-Newtonian behavior. Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, a modified Reynolds equation has been obtained. Assuming linear behavior for the magnetic material of the ferrofluid, the magnetic force was calculated. The Reynolds equation has been derived to be able to apply to any magnetic field distribution model. Using different magnetic field models, the equation has been solved numerically by the finite-difference technique with appropriate iterative technique and pressure distributions have been obtained. The boundary shape of the load-carrying active regions (positive-pressure regions) and cavitation regions (zero-pressure regions) could be then determined. The solution renders the bearing performance characteristics, namely: load-carrying capacity, attitude angle of the journal center, frictional force at the journal surface, friction coefficient and bearing side leakage. The results indicated that the flow-behavior index has a large effect on the bearing performance. When the bearing operates at high eccentricity ratios, the increase of flow-behavior index gives higher load capacity, lower attitude angle, higher frictional force, lower friction coefficient and higher side leakage. At low eccentricity ratios where the magnetic effects are significant, the effect of the flow-behavior index depends mainly on the magnetic field distribution model used.

This work represents a comparative study of different approaches of manipulating ratio spectra, applied on a binary mixture of ciprofloxacin HCl and dexamethasone sodium phosphate co-formulated as ear drops. The proposed new spectrophotometric methods are: ratio difference spectrophotometric method (RDSM), amplitude center method (ACM), first derivative of the ratio spectra (1DD) and mean centering of ratio spectra (MCR). The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. The proposed methods were validated according to the ICH guidelines. A comparative study was conducted between those methods regarding simplicity, limitations and sensitivity. The obtained results were statistically compared with those obtained from the reported HPLC method, showing no significant difference with respect to accuracy and precision.

In this study, 512 milk samples from different sources were
examined .The incidence of Listeria among the different ruminant species
revealed that the percentage of Listeria isolation reached 6.1%. The
isolated Listeria spp. were distributed as 9 strains from cows, 8 strains
from buffaloes, 6 strains from goats, 8 strains from ewes and 4 strains
from she –camels raw milk. The Listeria spp were distributed as 7 strains
of L. monocytogenes, 4 strains L. innocua, 8 strains L. welshimeri, 7
strains L. seelegeri and 5 strains L. grayi in a percentage of 1.4%, 0.8%, 1.6%, 1.4% and 0.98%, respectively.
The results of virulence study revealed that all of the tested Listeria isolates were strong positive for Congo red after 24 hrs. The Listeria monocytogenes isolates induced severe vaculation and detachment in vero cells but the other Listeria spp. did not induce any change. Virulence of the Listeria isolates was also investigated by i/p injection to mice, intraocular distillation in rabbits and intraallantoic inoculation in ECG. Death occurred to mice and chick embryos and eye inflammation in rabbits within 24h after injection in an incidence of 100% (toxigenic). On the other hand the suspected isolates of L. innocua, L. seelegeri, L. welshimeri and L. grayi showed negative results (non toxigenic). The results of biofilm formation showed that the L. monocytogenes from goat and she-camel show high degree to form biofilm to plastic surface than other strains although L. monocytogenes type 4 has a strong degree to form biofilm with glass surfaces than type 1 while L. innocua, L. grayi and L. welshemeri showed a lesser degree to form biofilm to plastics surface. L. seelegeri from cow milk and goat milk showed high degree to form biofilm to plastic surfaces. L. innocua from cow milk and buffaloes milk has strong degree to form biofilm with glass surface while other Listeria spp (L. welshemeri and L. grayi) ranged from moderate to weak.
The antibiogram for Listeria isolates revealed that all isolates showed resistance for the following antibiotics: cloxacillin, oxacillin, pefloxacin, flumoquine, cephalosporin, bacitracin, lincomycin, clindamycin.
It was obvious that the Listeria isolates showed a significant effect of Listeria on the level of nitric oxide and the effect on the lysozyme level was also significant except in buffalo milk.