Improving the throughput of plasticating extruders : manufacture of non-circular pellets, measurement of their interparticulate friction coefficient, and implications for screw design

This dissertation addresses the hypothesis that the interparticulate friction coefficient of a bed of polymeric particulates is a function of the cross-section of the pellets. Most pellets have a circular cross-section especially those that are strand cut. But when such pellets constitute a particulate bed there are few restrictions to adjacent pellets turning with respect to each other, or of the beds rupturing under shear load. This rupture can occur in plasticating extrusion, and it results in a poorly mixed melt with an inhomogeneous temperature distribution. The temperature fluctuations cause viscosity fluctuations which in turn cause pressure fluctuations. The pressure fluctuations cause throughput variations which lead to thickness variations in the product. That results in poor quality product. This sequence of events is termed surging. If the rupture of the solid bed can be prevented then surging can be curtailed. An increase in the interparticulate friction coefficient is expected to reduce solid bed rupturing. And the interparticulate friction coefficient can be increased if pellets with non-circular cross-section constitute it. Due to the fact that trilobal fibers are used to provide interlocking in the textile industry, the trilobal cross-section was first tested. This led to tests on bilobal and quadrilobal cross-sections as well. However, prior to testing the pellets required manufacture. Since bilobal, trilobal and quadrilobal cross-sections are different profile cross-sections, it was first necessary to design and build a series of profile extrusion dies. Each die was capable of producing a variety of pellet cross-sections if the material was changed, or if the throughput rate was varied. So many pellet geometries could be readily produced. Each variation of material and geometry was tested independently in a direct shear cell to measure the interparticulate friction coefficient. It was clearly found that the highest interparticulate friction coefficients occurred with pellets of bilobal cross-section, a 31% to 81% increase over pellets with circular cross-section. In addition pellets with trilobal and quadrilobal cross-section exhibited an improved interparticulate friction coefficient, a 20% to 34% increase compared to pellets with circular cross-sections. Consolidation pressure and time had minimal effects whereas agitation caused interparticulate friction coefficient increases from 51% to 89%. The effect of additives in the particulate continuum on the interparticulate friction coefficient was also studied. Since production runs could not be made to test if surging could in fact be reduced, due to the vast amounts of feedstock required, resort was made to numerical experimentation. An existing software package was modified to allow study of the transport of a portion of the solid bed. In this way rupture could be predicted based on the value of the interparticulate friction coefficient. Thus it could be inferred that surging would be reduced

Acute exacerbation of psychiatric symptoms during influenza treatment with oseltamivir in chronic schizophrenia

AbstractInfluenza treatment and prophylaxis with oseltamivir are critically important in reducing the morbidity and mortality of patients in chronic psychiatric facilities. Abnormal behavior, delusions, perceptual disturbances, mania, and depression have all been reported as oseltamivir-related psychiatric side effects. We hereby report two chronic schizophrenia patients in Taiwan manifesting psychiatric instability who were being treated with oseltamivir for suspected influenza infection, and further discuss other potential contributing factors. The possibility that oseltamivir can cause psychotic or affective symptoms suggests that additional caution is necessary for its use in patients with an established psychiatric diagnosis

Credit Scoring Based on Hybrid Data Mining Classification

The credit scoring has been regarded as a critical topic. This study proposed four approaches combining with the NN (Neural Network) classifier for features selection that retains sufficient information for classification purpose. Two UCI data sets and different approaches combined with NN classifier were constructed by selecting features. NN classifier combines with conventional statistical LDA, Decision tree, Rough set and F-score approaches as features preprocessing step to optimize feature space by removing both irrelevant and redundant features. The procedure of the proposed algorithm is described first and then evaluated by their performances. The results are compared in combination with NN classifier and nonparametric Wilcoxon signed rank test will be held to show if there has any significant difference between these approaches. Our results suggest that hybrid credit scoring models are robust and effective in finding optimal subsets and the compound procedure is a promising method to the fields of data mining

2-(2H-Benzotriazol-2-yl)-6-[(diethyl­amino)meth­yl]-4-methyl­phenol

In the title compound, C18H22N4O, the dihedral angle between the planes of the benzotriazol unit and the phenyl ring of the phen­oxy group is 6.4 (2)°. There is an intra­molecular O—H⋯N hydrogen bond between the phenol and benzotriazol groups

A rare, highly aggressive primitive neuroectodermal tumor of the kidney: Case report and literature review

AbstractWe report a case of a 14-year-old boy who initially suffered from a sudden onset of abdominal pain for 2 weeks with a protrusive soft mass over the left upper abdomen. No obvious symptomatic symptoms or body weight loss were observed. However, early lung metastasis was detected after an initial computed tomographic examination. Even after we performed salvage en bloc resection of the huge retroperitoneal tumor after primary neoadjuvant chemotherapy, the final outcome was still poor. A diagnosis according to radiologic findings was uncharacteristic. Finally, a pathologic diagnosis based on histologic and immunohistochemical results revealed a rare renal peripheral primitive neuroectodermal tumor

LrrA, a novel leucine-rich repeat protein involved in cytoskeleton remodeling, is required for multicellular morphogenesis in Dictyostelium discoideum

AbstractCell sorting by differential cell adhesion and movement is a fundamental process in multicellular morphogenesis. We have identified a Dictyostelium discoideum gene encoding a novel protein, LrrA, which composes almost entirely leucine-rich repeats (LRRs) including a putative leucine zipper motif. Transcription of lrrA appeared to be developmentally regulated with robust expression during vegetative growth and early development. lrrA null cells generated by homologous recombination aggregated to form loose mounds, but subsequent morphogenesis was blocked without formation of the apical tip. The cells adhered poorly to a substratum and did not form tight cell–cell agglomerates in suspension; in addition, they were unable to polarize and exhibit chemotactic movement in the submerged aggregation and Dunn chamber chemotaxis assays. Fluorescence-conjugated phalloidin staining revealed that both vegetative and aggregation competent lrrA− cells contained numerous F-actin-enriched microspikes around the periphery of cells. Quantitative analysis of the fluorescence-stained F-actin showed that lrrA− cells exhibited a dramatically increase in F-actin as compared to the wild-type cells. When developed together with wild-type cells, lrrA− cells were unable to move to the apical tip and sorted preferentially to the rear and lower cup regions. These results indicate that LrrA involves in cytoskeleton remodeling, which is needed for normal chemotactic aggregation and efficient cell sorting during multicellular morphogenesis, particularly in the formation of apical tip

Subclinical myocardial disease by cardiac magnetic resonance imaging and spectroscopy in healthy HIV/Hepatitis C virus-coinfected persons.

Objective The contribution of hepatitis C virus (HCV) infection to the risk of heart failure in human immunodeficiency virus (HIV)-coinfected persons is unknown. The objective was to characterize cardiac function and morphology in HIV-treated coinfected persons. Methods In a cross-sectional study, HIV-infected patients virologically suppressed on antiretroviral therapy without known cardiovascular disease or diabetes mellitus underwent cardiac magnetic resonance imaging and spectroscopy for measures of cardiac function, myocardial fibrosis, and steatosis. Results The study included 18 male patients with a median age of 44 years. Of these, 10 had untreated HCV coinfection and eight had HIV monoinfection. Global systolic and diastolic function in the cohort were normal, and median myocardial fat content was 0.48% (interquartile range 0.35-1.54). Left ventricular (LV) mass index and LV mass/volume ratio were significantly greater in the HIV/HCV-coinfected group compared with the HIV-monoinfected group. In the HIV-monoinfected group, there was more myocardial fibrosis as measured by extracellular volume fraction. Conclusions There were differences between HIV/HCV-coinfected and HIV-monoinfected patients in cardiac structure and morphology. Larger studies are needed to examine whether HIV and HCV independently contribute to mechanisms of heart failure