Comparison of physicomechanical properties of films prepared from organic solutions and aqueous dispersion of Eudragit RL

Mechanical properties of films prepared from aqueous dispersion and organic solutions of Eudragit RL were assessed and the effects of plasticizer type, concentration and curing were examined. Films were prepared from aqueous dispersion and solutions of Eudragit RL [isopropy alcohol-water 9:1] containing 0, 10 or 20% [based on polymer weight] of PEG 400 or Triethyl Citrate [TEC] as plasticizer using casting method. Samples of films were stored in oven at 60°C for 24 hrs [Cured]. The stress-strain curve was obtained for each film using material testing machine and tensile strength, elastic modulus,%elongation and work of failure were calculated. The films with no plasticizer showed different mechanical properties depending on the vehicle used. Addition of 10% or 20% of plasticizer decreased the tensile strength and elastic modulus and increased%elongation and work of failure for all films. The effect of PEG 400 on mechanical properties of Eudragit RL films was more pronounced. The differences in mechanical properties of the films due to vehicle decreased with addition of plasticizer and increase in its concentration. Curing process weakened the mechanical properties of the films with no plasticizer and for films with 10% plasticizer no considerable difference in mechanical properties was observed before and after curing. For those with 20% plasticizer only films prepared from aqueous dispersion showed remarkable difference in mechanical properties before and after curing. Results of this study suggest that the mechanical properties of the Eudragit RL films were affected by the vehicle, type of plasticizer and its concentration in the coating liquid

Comparison between different models for rheological characterization of activated sludge

Activated sludge flow rheology is a very complicated phenomenon. Studies related to activated sludge tend to classify sludge as non-Newtonian fluid. Until now, several theories have been built to describe the complex behavior of activated sludge with varying degrees of success. In this article, seven different models for viscosity of non-Newtonian fluids [i.e., Power law, Bingham plastic, Herschel-Bulkley, Casson, Sisko, Carreau and Cross] were considered to evaluate their predictive capability of apparent viscosity of activated sludge. Results showed that although evaluating the constants in the four-parameter models is difficult, they provide the best prediction of viscosity in the whole range of shear rates for activated sludge. For easier prediction of viscosity at different mixed liquor suspended solids [2.74-31g/L], temperature [15-25°C] and shear rate [1-1000/s], simple correlations were proposed. Comparing the results with the experimental data revealed that the proposed correlations are in good agreement with real apparent viscosities

[Designing of human cartilage tissue, by differentiation of adipose-derived stem cells with BMP-6 in alginate scaffold]

In the present study the effect of BMP-6 was investigated on chondrogenesis of adipose-derived stem cells. Mesenchymal stem cells derived from subcutaneous adipose tissue were cultured on alginate scaffold to induce chondrogenesis in experimental group, with chondrogenic medium having BMP-6 growth factor for 3weeks. In control group medium without BMP-6 was applied. The harvested constructs were examined with immunohistochemical and RT-PCR methods for assessment of cartilage-specific characteristics. The results of immunohistochemical method revealed the presence of typical cartilage extracellular matrix components such as type II collagen and aggrecan in constructs induced by BMP-6 growth factor on alginate scaffold. In addition evaluation of the results of RT-PCR analysis confirmed the expression of cartilage- specific genes, such as type II collagen and aggrecan, in the differentiated cells under the influence of growth factor BMP-6. It can be concluded that BMP-6 promotes chondrogenesis of ADSC in 3-D and adipose-derived stem cells could be used for cartilage tissue engineering

Protective effect of Johne's disease attenuated vaccine in an intensive non-tuberculosis free dairy

This study was carried out to control Johne's disease [JD] without interfering with tuberculosis [TB] control programme. A dairy herd [n>1500 heads] was used over a period of 6 years, from 1994 to 1999 for this investigation. The herd had a history of heavy infection with Mycobacterium avium paratuberculosis [MAP] with culling rates of 1.5 and 5%, in 1991 and 1995, respectively. The mean annual losses due to the reduction in milk yield, pregnancy rate and carcass weight was about $32000. In addition, the farm has had positive tuberculin test. During this study, 2070 calves within 31 days of age, were inoculated once subcutaneously, with MERIAL JD attenuated vaccine, in the middle of brisket region. The vaccine protected the herd against JD effectively, so that from 1995 up to the end of 1999, the means of JD culling among 2-year-old vaccinated and unvaccinated cattle were 0.52 and 19.4%, respectively. This vaccination had no side-effects on TB control programme that was conducted by the comparative tuberculin test. In the site of inoculation, fibrocaseous inflammation, while increasing in size, was developed. during 2 years, on the majority of animals, this reaction disappeared; only in less than 1.5% of instances the lesion became tumoral. and permanent. These animals had no clinical abnormality. While inoculating the vaccine, the insertion of vaccine germ contaminated needles in fingers of vaccinators usually caused temporary, hard and painful inflammation. In one occasion, a progressive granuloma caused by vaccine germ was diagnosed histopathologically and treated with suitable antibiotics