Modeling of free radical polymerization up to high conversion. I. A method for the selection of models by simultaneous parameter estimation

A systematic quantitative method for the selection of models for the high-conversion free radical polymerization exhibiting gel and glass effects has been developed. Four representative models were selected from the literature and were compared on the basis of the same experimental data. All models describe the isothermal time-conversion data over the entire conversion range for a single type and loading of initiator well. Models that are not considering the effect of molecular weight of the polymers on the diffusion of macro radicals fail to describe the time-conversion data if the concentration of the initiator varies at the same time. By simultaneous fitting of the conversion and polymerization degree data it was shown that the Marten-Hamielec model and its extended form (Panke-Stickler-Hamielec model) were not able to describe the number average polymerization degree Pn at the final conversion, where the glass effect occurs. This occurred because both models neglect the change of the radical efficiency f in this region, which has more effect on Pn than the change of the propagation rate coefficient (see part II of this series)

Reproductive Characteristics of Abyssinian Jennies Exposed to Stallions and Jackasses

The aim of the study was to describe the intraspecies and interspecies sexual interactions and reproductive features Abyssinian type jennies exposed to jackasses and stallions. Twenty post-pubertal jennies, 3 jackasses and 4 stallions were used in the study. Jennies were divided in to two groups of ten each (stallion group and jack group). PGF2a was used to induce heat. A vasectomized jackass was used to assist heat detection. Jennies in the jack group were bred by two jackasses and jennies in the stallion group were bred by a stallion. Mating was on the 6th and 8th days after PGF2a injection and within the last three days after spontaneous return to heat. The durations of estrus and the estrus cycle were 7.4 ± 0.9 (mean ± SD) and 24.3 ± 2.1 (mean ± SD) days respectively. All jennies were receptive to jackasses but not to stallions. The number of cycles per pregnancy in the intraspecies mating was lower than the number of cycles in the interspecies mating (p < 0.05). The lengths of gestation of jennies in foal with jackasses and a stallion were 370.2 ± 4.5 (mean ± SD) and 330 days respectively. The mating resulted in five donkey foals and a hinny. The study showed that Abyssinian jennies have a high intraspecies reproductive potential but low pregnancy rate and abortion appear limitations in interspecies hybridization.Key words: Hinny, Jackass, Jenny, Reproduction, Stallio

Total polyphenol content of green, roasted and cooked Harar and Yirgacheffee Coffee, Ethiopia

The effect of solvent composition on the total polyphenols content of green, roasted coffee and traditional coffee beverage preparation stages (Abol, Tona and Bereka) were studied by UV-Vis spectroscopy. The maximum extracted polyphenol of 640.3 mg GAE/100 g and 641.9 mg GAE/100 g were obtained at Harar and Yirgacheffee green coffee extracts with at 85% methanol, respectively. The results showed that total phenolic contents of extracts were found to be in the order of green> roasted >cooked (Abol>Tona>Bereka) in both coffee samples. Application of ANOVA revealed that a significant variation (p <0.05) was noted between the green, roasted, Abol, Tona and Breka coffee processing procedures. In general, this study revealed that there was a loss of substantial amount of total polyphenols through the traditional way of coffee brewing, probably ascribed to continuous provision of heating leads to degradation of existing polyphenols and formation of less stable and volatile products.Keywords: Coffee, Green, Roasted, Cooked, Polypheno

Assessing Control of Asthma in Jush, Jimma, South West Ethiopia

Background: Despite international guidelines, asthma control is short of the goal in different parts of the world. The objective of this study was to assess control of asthma in patients older than 14 years at the Chest Clinic of Jimma University Specialized Hospital/JUSH, South West Ethiopia.Methods: A cross-sectional hospital-based study was conducted on 234 physician-diagnosed asthmatic patients attending the chest follow up clinic from June 01 to July 31, 2012. Asthma control was assessed using the GINA algorithm and the ACT questionnaire. Pulmonary function test was measured using a spirometer for 160 subjects. Data were cleared, entered and analyzed using SPSS version 16 and independent variables were assessed for association with the level of asthma control using bivariate and multinomial analyses.Results: Using the GINA based algorithm, 42 respondents (26.2%) were considered to have partly controlled asthma and the majority, 117 (76.1%), had uncontrolled asthma. Asthma was uncontrolled (ACT score <19) in 71.4% subjects and well-controlled (ACT score = 20-25) in 28.6%. Inhaled corticosteroids alone or in association with long-acting b-agonists, which are the prophylactic treatments recommended by GINA, were used by only 9 subjects (3.8%). Factors associated independently with asthma control were individual patient’s age group, unscheduled visit, frequency of SABA use, type of treatment and perceived rate of asthma control.Conclusion: Asthma control is unacceptably poor in Jimma, South West Ethiopia. This could be changed through improved appropriate treatment and frequent monitoring to achieve and maintain control.Keywords: Control of asthma, Spirometry, Asthma treatment, Sub-Saharan Afric

Abdominal Surgical Emergencies at Tikur Anbessa Specialized Hospital in Ethiopia; A Shifting Paradigm

Background: Developing nations in Africa may be experiencing changing demographics for abdominal surgical emergencies. In the past, intestinal obstruction has been the major diagnosis, but this may be changing.123 This study analyzed the causes and outcomes for abdominal surgicalemergencies (ASE) in Tikur Anbessa Specialty Hospital (TASH) in Addis Ababa, Ethiopia.Methods: TASH is a tertiary medical center and teaching hospital. This is retrospective study included patients treated for ASE from July 1, 2010 to June 30, 2012. Information was collected in de-identified manner for analysis from the operating room logbook and from chart review. We analyzed demographics, clinical presentation and outcomes of emergency surgery in these patents using SAS 9.2 software. Univariant analysis was performed. P value < 0.05 was considered significant.Results: A total of 530 patients presented with ASE, representing 18.6% of all surgical emergencies. Of these, 328 charts were available for review. 237 (72.3%) were males and the mean age was 36 years. Appendicitis (simple and complicated combined) were the most common cause of ASE accounting for 92 (28.0%). Bowel obstruction and penetrating trauma were present in 17% and 13% of the time respectively. The Overall Morbidity and mortality rates were 30% and 18% respectively. Wound infection andPneumonia were the two most common post operative complications  accounting for 25% and 12% respectively. A total of 61 patients (18.6%) died following ASE. Septic complications accounted for over 50% of the death. Mortality was significantly higher in patients with age >60 years (p<0.0001) and in those who developed post operative complications. (p< 0.0001)Conclusion: The causes for ASE at TASH in Ethiopia have changed with appendicitis being the most common. This study shows a higher morbidity and mortality rates when compared to previous reports. Further study is required to understand better specific interventions needed to reduce thishigh mortality due to sepsis