Propane Oxidative Dehydrogenation Under Oxygen-free Conditions Using Novel Fluidizable Catalysts: Reactivity, Kinetic Modeling and Simulation Study

Propane oxidative dehydrogenation (PODH) was studied using VOx/γAl2O3 and VOx/ZrO2-γAl2O3 (1:1 wt.%) catalysts, as well as consecutive propane injections under oxygen-free conditions. These catalysts were synthesized with 2.5, 5 and 7.5 wt.% vanadium loadings, and prepared using a wet saturation impregnation technique. Different characterization techniques were used to establish catalyst properties including NH3-TPD, pyridine FTIR and NH3-TPD kinetics. As well, PODH runs in the CREC Riser Simulator were developed under oxygen free atmospheres at 500-550°C, close to 1 atm., 10-20 s and 44.0 catalyst/propane weight ratio (g/g). Propylene selectivity obtained were up to 94%, at 25% propane conversion. Using this data, a “parallel-series” model was established based on a Langmuir-Hinshelwood rate equation. Adsorption constants were defined independently, with this leading to a 6-independent intrinsic kinetic parameter model. These parameters were calculated via numerical regression with reduced spans, for the 95% confidence interval and low cross-correlation coefficients. A larger 2.82×10-5 mol.gcat-1s-1 frequency factor for propylene formation versus the 1.65×10-6 mol.gcat-1s-1 frequency factor for propane combustion was obtained. The calculated energies of activation (55.7 kJ/mole for propylene formation and 33.3 kJ/mole for propane combustion) appeared to moderate this effect, with the influence of frequency factors prevailing. Furthermore, propylene conversion in COx oxidation appeared as a non-favored reaction step, given the 98.5 kJ/mole activation energy and 4.80×10-6 mol.gcat-1s-1 frequency factor. This kinetic model was considered for the development of a scaled-up twin fluidized bed reactor configuration. For this, a hybrid computational particle-fluid dynamic (CPFD) model featuring either “Particle Clusters” or “Single Particles” was employed. Results obtained in a 20-m length downer unit showing a 28% propane total conversion and a 93% propylene selectivity using the “Single Particle” model. However, and once the more rigorous particle cluster flow was accounted for, propane conversion was limited to 20%, with propylene selectivity staying at 94% level. Thus, the obtained results show that a PODH simulation using CPFD requires one to account for “Particle Clusters”. This type of comprehensive model is needed to establish unambiguously the PODH downer reactor performance, being of critical value for the development of down-flow reactors for other catalytic processes

Sexual dysfunction and its determinants in Moroccan women with rheumatoid arthritis

Introduction: To assess the prevalence of sexual dysfunction in married women with rheumatoid arthritis (RA) and compare it with a control group and to determine its association with clinical and disease activity factors. Methods: We conducted a cross-sectional study including sixty married women with a confirmed diagnosis of Rheumatoid Arthritis according to the American College of Rheumatology (ACR)/ European League against Rheumatism (EULAR) 2010 Criteria, aged 18 or over and having sexual activity. Our controls were healthy volunteers women matched for age. Clinical and sociodemographic characteristics were collected. Sexual function was assessed by a self-reported questionnaire the index of female sexual function (FSFI). Sociodemographic and disease activity profiles were compared between those who had and did not have sexual dysfunction. Results: The prevalence of female sexual dysfunction in women with rheumatoid arthritis attending El Ayachi hospital was 71.9%, it was 54% in controls. There was a significant difference in the total FSFI score between patients 18.29±9.09 and controls 23.05±7.91 (p=0.016). We found a statistically significant difference between the two groups in almost all dimensions of sexual function (desire, arousal, orgasm, satisfaction), except for pain and lubrication. In multivariate analysis, pain assessed by visual analogue scale (VAS) and depression assessed by hospital anxiety and depression score (HAD) were the independent determinants of sexual dysfunction. Conclusion: Our study suggests that sexual dysfunction is more common among patients with RA compared to controls. These dysfunctions were related to desire, arousal, orgasm and satisfaction. Pain and depression appear to be the most important predictors of sexual dysfunction.Pan African Medical Journal 2016; 2

Factors influencing quality of life in Moroccan postmenopausal women with osteoporotic vertebral fracture assessed by ECOS 16 questionnaire

<p>Abstract</p> <p>Objective</p> <p>The aim of the study was to evaluate factors influencing quality of life (QOL) in Moroccan postmenopausal women with osteoporotic vertebral fracture assessed by the Arabic version of ECOS 16 questionnaire.</p> <p>Methods</p> <p>357 postmenopausal women were included in this study. The participants underwent bone mineral density (BMD) measurements by DXA of the lumbar spine and the total hip as well as X-ray examination of the thoraco-lumbar spine to identify subclinical vertebral fractures. Patients were asked to complete a questionnaire on clinical and sociodemographic parameters, and osteoporosis risk factors. The Arabic version of the ECOS16 (Assessment of health related quality of life in osteoporosis questionnaire) was used to assess quality of life.</p> <p>Results</p> <p>The mean age was 58 ± 7.8 years, and the mean BMI was 28.3 ± 4.8 kg/m². One hundred and eight women (30.1%) were osteoporotic and 46.7% had vertebral fractures. Most were categorized as Grade1 (75%). Three independent factors were associated with a poor quality of life: low educational level (p = 0,01), vertebral fracture (p = 0,03), and history of peripheral fracture (p = 0,006). Worse QOL was observed in the group with vertebral fracture in all domains except "pain": Physical functioning (p = 0,002); Fear of illness (p = 0,001); and Psychosocial functioning (p = 0,007). The number of fractures was a determinant of a low QOL, as indicated by an increased score in physical functioning (p = 0,01), fear of illness (p = 0,007), and total score (p = 0,01) after adjusting on age and educational level. Patients with higher Genant score had low QOL in these two domains too (p = 0,002; p = 0,001 respectively), and in the total score (p = 0,01) after adjusting on age and educational level.</p> <p>Conclusion</p> <p>Our current data showed that the quality of life assessed by the Arabic version of the ECOS 16 questionnaire is decreased in post menopausal women with prevalent vertebral fractures, with the increasing number and the severity of vertebral fractures.</p

An Eco-Friendly Fluidizable FexOy/CaO-γ-Al2O3 Catalyst for Tar Cracking during Biomass Gasification

The present study deals with the development, characterization, and performance evaluation of an eco-friendly catalyst, using 2-methoxy-4-methylphenol (2M4MP) as a surrogate tar. The 2M4MP was selected due to its chemical functionalities and the fact that it is a good model compound to represent the tar formed during biomass low temperature gasification. The eco-friendly catalyst was prepared using the typical Fe and Ca minerals which are present in ash. These ash components were added to a fluidizable &gamma;-Al2O3 support using a multistep incipient impregnation, yielding Fe oxides as an active phase and CaO as the promoter. The prepared catalyst displayed a 120 m2/g BET specific surface area, with few &gamma;-Al2O3 bulk phase changes, as observed with XRD. TPD-NH3 and pyridine FTIR allowed us to show the significant influence of CaO reduced support acidity. A TPR analysis provided evidence of catalyst stability during consecutive reduction&ndash;oxidation cycles. Furthermore, catalyst evaluation vis-&agrave;-vis catalytic steam 2M4MP gasification was performed using the fluidized CREC riser simulator. The obtained results confirm the high performance of the developed catalyst, with 2M4MP conversion being close to 100% and with selectivities of up to 98.6% for C1-C2 carbon-containing species, at 500 &deg;C, with a 7.5 s reaction time and 1.5 g steam/g 2M4MP. These high tar conversions are promising efficiency indicators for alumina catalysts doped with Fe and Ca. In addition, the used catalyst particles could be blended with biochar to provide an integrated solid supplement that could return valuable mineral supplements to the soil

Prevalence of osteoporosis and osteoporotic fractures in postmenopausal women with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) and osteoporosis are chronic diseases with increasing prevalence. The aim of this study was to determine the prevalence of osteoporosis and osteoporotic fracture in women with T2DM and to identify predictive factors of fracture occurrence. The prevalence of osteoporosis and fractures in postmenopausal women with T2DM was 23.1% and 16.9%, respectively. 46.2% of T2DM patients had normal bone mineral density (BMD) (P<0.01) and 58.5% of control subjects had osteopenia (P<0.01). Incidence of fracture in T2DM patients with osteopenia was significantly increased versus control subjects when stratified according the BMD (P=0.009). By stratifying T2DM patients according to fractures, factors that were significantly associated with occurrence included T2DM duration (P=0.038), use of insulin (P=0.017), and lower BMD (P=0.048). Our study suggests that there was a higher prevalence of fracture in T2DM patients compared to control subjects and a significant difference in BMD was found between the groups. We also showed that insulin use, low BMD, and long duration of T2DM are factors associated with an increased risk of bone fracture

The relation between disease activity, vitamin D levels and bone mineral density in men patients with ankylosing spondylitis

The aim of this study was to assess the vitamin D status in patients with ankylosing spondylitis (AS), and to investigate the relation between vitamin D levels, bone mineral density (BMD) and disease activity in men with ankylosing spondylitis. Seventy patients with AS and 140 healthy individuals were included in the study. BMD of femur and lumbar spine was measured by DXA. Serum 25OH vitamin D, parathormone, serum calcium, C-reactive protein levels of all participants were also measured. The disease activity was evalu ated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and functional status by Bath Ankylosing Spondylitis Functional Index (BASFI). The mean 25(OH)D level was 17.5+9.7 ng/mL in AS patients and 21.9+7.7 ng/mL in controls (P&lt;0.001). In comparison with the control group, AS patients showed significantly higher CRP, and a significant reduction of vitamin D. In AS group, 62 patients (88.6%) had Vitamin D deficiency, and 35 patients (50%) were osteoporotic. Vitamin D was negatively correlated to BASDAI without any changes after adjustment for age, duration of disease, sunlight exposure, and total taking steroids (r=-0.32, P&lt;0.001).We found a high incidence of vitamin D deficiency in our patients. Our study suggests that vitamin D deficiency in male AS may indirectly lead to osteoporosis by causing an increase in the inflammatory activity. Monitoring vitamin D levels would be useful in order to determine the patients under osteoporosis risk