Life Time Improvement of Hierarchically Structured SAPO-34 Nanocatalyst in MTO Reaction via Applying Clinoptilolite: Investigating of Composite Design via RSM.

AIM AND OBJECTIVE: The research focuses on recent progress in the production of light olefins. Hence, as the common catalyst of the reaction (SAPO-34) deactivates quickly because of coke formation, we reorganized the mechanism combining SAPO-34 with a natural zeolite in order to delay the deactivation time. MATERIALS AND METHODS: The synthesis of nanocomposite catalyst was conducted hydrothermally using experimental design. Firstly, Clinoptilolite was modified using nitric acid in order to achieve nano-scaled material. Then, the initial gel of the SAPO-34 was prepared using DEA, aluminum isopropoxide, phosphoric acid and TEOS as the organic template, sources of Aluminum, Phosphor, and Silicate, respectively. Finally, the modified zeolite was combined with SAPO-34's gel. RESULTS: 20 different catalysts due to D-Optimal design were synthesized and the nanocomposite with 50 weight percent of SAPO-34, 4 hours Crystallization and early Clinoptilolite precipitation showed the highest relative crystallinity, partly high BET surface area and hierarchical structure. CONCLUSION: Different analyses illustrated the existence of both components. The most important property alteration of nanocomposite was the increment of pore mean diameters and reduction in pore volumes in comparison with free SAPO-34. Due to the low price of Clinoptilolite, the new catalyst renders the process as economical. Using this composite, according to the formation of multi-sized pores located hierarchically on the surface of the catalyst and increased surface area, significant amounts of Ethylene and Propylene, in comparison with free SAPO-34, were produced, as well as the deactivation time was improved.

An unusual case of bilateral anterior shoulder and mandible dislocations.

Unilateral anterior shoulder dislocation is the most common major joint dislocation seen by emergency physicians. Bilateral glenohumeral dislocations are rarely seen and almost always posterior after seizure or electrical shock. We present an unusual case of bilateral anterior dislocation of shoulder that had anterior dislocation of temporomandibular joint simultaneously. These problems occurred after a course of generalized tonic-clonic seizure. The coincidence of these dislocations is the first case published in the literature.

Medical student and patient perspectives on bedside teaching.

OBJECTIVE: To evaluate the perspectives of medical students and patients on bedside teaching (BST). METHODS: A cross-sectional study was undertaken to elicit patients and learners opinions on BST in Hazrat Rasool Hospital, a university teaching hospital in Tehran, Iran. From June 2008 to September 2008, 100 fourth-year medical students and 100 adult patients admitted to the general medical service of a teaching hospital were chosen randomly. Patients who stayed for a minimum of 48 hours and had at least 2 case presentations in 2 consecutive mornings were included in the study. Patients under 18 years of age, non-Persian speakers, and cognitively impaired were excluded from the study. Their perspectives on BST were assessed with 2 separate questionnaires. RESULTS: The mean age of medical students was 25.2 +/- 2.2 (22-36) years and 35% were male. The mean age of patients was 46.3 +/- 18.7 (17-85) years and 50% were male. Most of medical students believed that BST is an effective way for learning principle of history taking, physical examination, practical skills, data registry, communicating skills, evidence based medicine, and interpretation of para-clinical findings. Fifty-three percent of them believed that the time of BST is not enough, while 40% thought BST is the most effective way of learning clinical skills. Sixty percent of patients were comfortable with BST and 80% of them preferred that case presentation be performed in front of them. CONCLUSION: Our study suggests that teaching in the presence of patients provides unique and valuable opportunities to integrate the knowledge and skills of medicine for the direct benefit of the patient.