Isothermal kinetics of exchange of water absorbed in calcium alginate hydrogel with ethanol

The isothermal kinetics of the exchange of absorbed water in calcium alginate hydrogels with ethanol was investigated. The isothermal kinetic curves were measured within the temperature range from 297 to 316 K. By the application of differential isoconversional methods, it was found that the process of exchange of water absorbed in calcium alginate hydrogel with ethanol has a unique rate determining step (a single step process). Using the model fitting method, it was determined that the kinetics of the exchange can be mathematically described with the kinetic model of the first-order chemical reaction. The values of the kinetic parameters of water exchange: the rate constants (km), energy of activation (Ea = 18.0 kJ∙mol–1), and the pre-exponential factor (ln[A/min–1] = 4.0) were calculated. By using Eyring's equation, the values of thermodynamics parameters: standard enthalpy of activation (ΔH*), standard entropy of activation (ΔS*), and Gibbs energy of activation (ΔG*) were calculated. It was found that the rate of rearrangements of the bound water around hydrophilic groups of a polymeric network has a dominant effect on the kinetics of the exchange of the absorbed water with ethanol. The mechanism of the exchange of adsorbed water with ethanol was suggested. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172015

Intellectual disabilities and intervention strategies: international approach

Introduction: This study focuses on the strategies of implementing practical activities in children with intellectual disabilities. It is aimed at encouraging and rehabilitating neuropsychological processes of attention, behaviour and cognition (visual and spatial abilities, elemental and complex motor abilities and conceptual functions). Subject: This study was aimed at children with mild intellectual disabilities with the emphasis on their cognitive and behavioural functioning in relation to different aspects of the applied treatment strategies. Material and methods: The sample consists of 124 examinees with mild intellectual disability, of both genders, aged between 8 and 13, attending primary schools in Belgrade. In this research we applied the Trial Making Test (TMT; Reitan, 1971) for attention assessment, the IOWA Conners' Rating Scale for Children for behaviour assessment, and the Test of Concept Utilization (TCU; Crager and Lane, 1981) for the assessment of cognitive functions. Results: The results indicate the presence of developmental disabilities in the examined areas in more than 50% of the tested children and a high statistically significant correlation between the applied treatment modalities and tested abilities and functions (r=0.52-0.59, df lt 0.01). The study points out the necessity of implementing the multimodal approach: team work of professionals and non-professionals (cooperation between professionals and parents), complementary treatment (medical and special treatment, psychosocial interventions, combination of treatment strategies), psychotherapy and psycho-pharmacotherapy when necessary, as well as special education and rehabilitation, based on individual education programs and individual training programs (IEP and ITP) and special rehabilitation procedures and methods. Conclusion: New treatment strategies, with the emphasis on special rehabilitation treatment, were proposed in conclusion

Primjena asistirane reprodukcije u govedarstvu

More than five decades of research in reproductive biology have resulting in the development of biotechnologies in the cattle industry to increase efficiency in beef and dairy production systems. These technologies are related to gamete and embryo manipulation aimed at improving fertility and genetic progress. The application of assisted reproductive technology in stockbreeding has tremendously altered the rate of genetic improvement in breeding programmes and strategies. Artificial insemination, embryo transfer and in vitro embryo production are technologies systematically applied in breeding programs around the world. They enable rapid genetic progress, shortening of the generation interval, control of disease transmission and reduction of production costs. Worldwide, artificial insemination has been the most efficient and useful way to improve the genetic quality of the herd. Over a period of thirty years, embryo transfer has become an internationally accepted technology with over 500, 000 in vivo produced embryos per year. The recommended handling procedures of the International Embryo Transfer Society enable the safe export of in vivo derived embryos, without the risk of disease transmission. Approximately 15% of embryos produced annually are produced by in vitro technology. This technology enables embryo production from cows of high genetic merit that cannot produce offspring by conventional reproduction. Improvements in OPU/IVF programs would have a great impact on the cattle industry and could replace the traditional MOET programs in the near future. Furthermore, they are important for the development and operation of a gene bank for the cryoconservation of animal genetic resources, to preserve indigenous and endangered breeds of cattle. In addition to genetic progress, the application of these biotechnologies in animal breeding permits high quality breeding stock to be available on the market and enables the application of advanced technologies. Semen and embryo sexing allows for identification and selection of sex, which can assist in the more efficient management of resources. Cloning and transgenesis have great potential in the cattle industry, though due to their low efficiency and high costs, these technologies are predominantly applied in experimental settings and the production of pharmaceuticals