One of the first applications of Simulated Moving Bed (SMB) technology was in p‐xylene recovery from mixed xylenes. The three main industrial processes for p‐xylene separation from mixed xylenes based on SMB technology are: UOP's Parex, IFP's Eluxyl, and Toray's Aromax. These units operate in liquid phase (T = 180°C and P = 9 bar), achieving high recovery of almost pure p‐xylene with high on‐stream efficiency and extended adsorbent life. In this work, the industrial scale SMB process is investigated from modeling, simulation, and optimization points of view, using experimentally measured xylene adsorption equilibrium and kinetics data on ion exchanged faujasite zeolite. The aim is to develop tools for training of SMB unit operators and choice of the best operating conditions. Useful studies for better understanding of the influence of the operating parameters, adsorbent packing, and separation requirements on unit productivity are presented. SMB unit revamping strategies and operative actions are proposed. The practical application of “separation volume” methodology in the selection of optimum operating conditions that lead to maximum p‐xylene productivity with minimal desorbent consumption is described. © 2006 American Institute of Chemical Engineers AIChE J, 2007

No abstract

No abstract

Endometrioma in an operative scar is rare. The majority of patients have no prior history of endometriosis, and symptoms may mimic postoperative hernias. Fine-needle aspiration biopsy (FNAB) can be a valuable diagnostic aid in the evaluation of these subcutaneous abdominal masses. We present the cytologic findings in three cases of abdominal wall endometriomas diagnosed by FNAB. The patients ranged from 31 to 51 years of age. None had a history of endometriosis, but all had prior abdominal operations (two abdominal hysterectomies for fibroids and one cesarean section). They presented 6 months to 7 years later with painful subcutaneous abdominal nodules in their scars ranging from 2 to 6 cm. FNAB was performed by a cytopathologist. The smears were cellular and comprised two distinct cell populations. An epithelial component consisted of flat sheets of polygonal cells with round to oval nuclei and scant cytoplasm. The second component consisted of clusters of fusiform stromal cells. Numerous hemosiderin-laden macrophages were noted in the background. Cytokeratin highlighted the epithelial clusters, and vimentin stained the stromal cells. Electron microscopy showed two epithelial cell types: one with cilia and abundant rough endoplasmic reticulum and the other with numerous microvilli and scattered mitochondria indicative of endometrial differentiation. FNAB provided a rapid and accurate preoperative diagnosis in each case.