Efeito da somatotrofina bovina (bST-r), do implante de progestágeno e do desmame por 72 horas na indução do estro e na taxa de prenhez em vacas

Este trabalho teve por objetivo avaliar a eficiência de tratamentos hormonais sobre a fertilidade de vacas de corte no pós-parto com diferentes condições corporais, durante a estação de monta de outono. Setenta e três vacas pluríparas cruzadas (Hereford x Nelore) criadas extensivamente, com condição corporal entre 2 e 4, foram pesadas e distribuídas em três grupos experimentais. O grupo GSED, constituído por 25 vacas, recebeu pessário vaginal (dia 0) contendo 250mg de acetato de medroxiprogesterona e 500mg de somatotropina bovina recombinante (bST-r). Na retirada dos pessários (dia 7), as vacas receberam 0,5mg de cipionato de estradiol e procedeu-se o desmame temporário dos bezerros por 72 horas. No grupo SED, 25 vacas receberam tratamento semelhante ao grupo GSED, porém não receberam bST-r. No grupo-controle, as 23 vacas somente foram separadas dos seus bezerros por 72h. Quando da retirada dos pessários as vacas foram colocadas com touros por 30 dias. Os animais foram pesados e avaliados quanto à condição corporal no início do experimento e na retirada dos touros (dia 37). Foi constatada perda média de peso de 0,648 kg/dia e os percentuais de estro foram de 26,1%, 33,3% e 56,5%, respectivamente, para os grupos controle, SED e GSED. O diagnóstico de gestação, realizado pela palpação retal 60 dias após a retirada dos touros, indicou percentuais de prenhez de 13,0%, 8,3% e 21,7%, respectivamente, para os grupos controle, SED e GSED (P=0,16), demonstrando que os programas hormonais adotados não foram eficientes no incremento das taxas de prenhez de vacas que perdiam peso entre 50 e 70 dias após o parto

Simulation, Optimization and Control of Heavy Oil Upgrading Processes: Application to a Delayed Coking Unit

Petroleum refineries have faced many challenges to remain competitive in the world fuels market. If, on the one hand, recovered crude oils are getting heavier and there is a decreasing demand for heating and residual fuels, on the other hand, the demand for transportation fuels and more value-added products is increasing, renewing the interest of the refineries on the bottom-of-the-barrel residue upgrading. However, the feedstock for heavy oil conversion units comprises large, multifunctional molecules. Thus, characterize it adequately is a complex task, making complicated the obtaining of accurate kinetic models. This paper proposes a proper approach to simulation, optimization and control of a delayed coking unit by using Aspen Plus software. A novel procedure to represent a given feed material by pseudocomponents is described and a stoichiometric model based on known fractional conversions was developed. PID control was implemented in the system and satisfactory results were achieved. This supposes that the proposed methodology can be useful to obtain more appropriate predictions of behaviour and yield for processes with difficult dynamics and it can be applied in several ways, as on the tracking of processes as well as on new optimization techniques and advanced control

Optimal fuzzy control of batch polymerization reactors: Application to PMMA production for biomedical purposes

The use of polymers in the biomedical field requires that such materials have a high degree of purity and specific properties, so that their production processes must be continuously monitored and manipulated. However, the control of polymerization reactors is considered a challenging task since such systems present non-linear and transient behaviour. In this study, in order to produce poly(methyl methacrylate) scaffolds for bone tissue engineering applications, an advanced control methodology based on fuzzy models and genetic algorithms (GA) was developed to control the temperature of a pilot-scale jacketed batch reactor in which methyl methacrylate polymerization takes place. Firstly, an optimal temperature trajectory was estimated using GA. Then, a fuzzy controller was designed and applied to adjust the reactor temperature to the instantaneous profile previously calculated. The proposed control algorithm was compared to conventional PID controller, proving to be robust and more suitable and reliable for such process type. © 2014 Elsevier B.V

Pilot-plant Simulation, Experimental Campaign and Rigorous Modeling of a Batch MMA Polymerization Reactor for the Fabrication of Bone Tissue

As a first crucial stage for production of PMMA scaffolds, this work provides the kinetic and dynamic characterization of the MMA/Ethyl Acetate/AIBN polymerization process. Kinetic parameters are estimated by means of experimental campaigns performed on a dedicated pilot plant (batch reactor). A novel, rigorous mathematical model is developed and implemented in Fortran 90 so as to consider the peculiar characteristics and the new structure of the pilot plant and the batch reactor: actually, the new plant configuration is designed to produce the appropriated PMMA scaffolds for medical application (with very stringent specifications for low toxicity and high biocompatibility). The good agreement between model previsions and experimental results validates the kinetic parameters and the dynamic modeling

Sistemas de inseminação artificial em dois dias com observação de estro ou em tempo fixo para vacas de corte amamentando Artificial insemination systems within two days of estrus detection or at fixed time for suckled beef cows

O objetivo do presente experimento foi investigar se a realização exclusiva da inseminação artificial em tempo fixo (IATF), empregando como indutor da ovulação o benzoato de estradiol (BE), proporciona taxas de prenhez semelhantes a uma associação de IA convencional e IATF com GnRH, em vacas de corte no pós-parto. Duzentos e cinqüenta vacas amamentado receberam um pessário vaginal contendo 250mg de acetato de medroxi-progesterona (MAP) e uma injeção intramuscular (IM) de 5mg de BE no dia 0. O pessário vaginal permaneceu por sete dias. No dia 6, foram aplicadas 400UI de gonadotrofina coriônica eqüina por via IM e 5mg de análogo de prostaglandina na submucosa vulvar, realizando nesse momento o desmame por 96h. Após a retirada dos pessários (dia 7), as vacas foram distribuídas em dois grupos. No grupo BioRep (n=150), as fêmeas foram observadas duas vezes por dia para detecção de estro por 48h e inseminadas 12h após sua manifestação. Os animais que não manifestaram estro nesse período receberam uma injeção IM de 100mg de GnRH, sendo submetidas à IATF, 16 a 18h após. No grupo BE (n=100), as vacas receberam uma injeção de 1mg de BE IM no dia 8 e foram inseminadas em tempo fixo no dia 9. A porcentagem de prenhez no grupo BioRep (54,7%) foi maior (P<0,01) do que no grupo BE (33,3%). Em vaca amamentando, a observação de estro por dois dias associada à IATF, utilizando GnRH para induzir a ovulação, proporcionou taxas de prenhez superiores ao uso exclusivo de IATF com BE.<br>This experiment was aimed at comparing two estrus induction protocols for cows in post partum period, using either GnRH and two-day artificial insemination (AI) or estradiol benzoate (EB) and fixed-time artificial insemination (TAI). A total of 250 suckled beef cows received a vaginal device containing 250mg of medroxyprogesterone acetate (MPA) and an injection of 5mg of EB intramuscularly (IM) on day 0. The vaginal device was removed on day 7. On day 6, cows were injected with 400IU eCG (IM) and 5mg prostaglandin analog (into vulvar submucosa) and calves were removed for 96 hours (h). After removing the vaginal devices (day 7), cows were divided in two groups. In the BioRep group (n=150), estrus detection was carried out twice a day during 48h and the animals were inseminated 12h after detection. Cows which were not detected in estrus received 100mg of GnRH IM and were inseminated 16 to 18h later. In EB group, cows were injected IM with 1mg of EB on day 8 and were inseminated on day 9 without estrus detection. The pregnancy rate was higher (P<0.01) in the BioRep group (54.7%) than in the EB group (33.3%). In suckled cows, two days of estrus detection associated to fixed-time insemination using GnRH to induce ovulation allowed the attainment of higher pregnancies rates than exclusively TAI using EB