Influence of ring-type internals on the solids residence time distribution in the fuel reactor of a dual circulating fluidized bed system for chemical looping combustion

The intensification of gas-solids contact in the fuel reactor of a chemical looping combustion system is enhanced with the installation of ring-type internals. This can be a key issue for achieving the necessary fuel conversion rates. Wedged rings, previously designed and tested, were found to increase the particle concentration in the counter current section of the fuel reactor and hence, to achieve a more homogeneous particles concentration along this zone. The present work investigates the effect of the mentioned internals on the residence time distribution of particles in the fuel reactor of a dual circulating fluidized bed system for chemical looping. The study was carried out in a cold flow model especially designed for the fluid-dynamic analysis of the system equipped with a recently developed residence time measurement device based on the detection of ferromagnetic tracer particles through inductance measurement. Ring internals proved the positive effect on the particles residence time, the residence time distribution is more symmetric and shows lower dispersion, the flow pattern is more plug-flow-like, these effects are intensified with the reduction of the aperture ratio of the rings. On the other hand, the upward particle transport in the counter-current zone of the fuel reactor also increases with the installation of the rings, increasing the bypass flow of solids through the fuel reactor's return loop (internal circulation). For high internal circulation rates the solids residence time distribution of the fuel reactor is dominated by the bypass effect. The findings may be used for focused design improvement of the investigated fluidized bed system.     

Admission to an intensive care unit after transvenous implantable cardioverter defibrillator implantation: analysis of risk factors

The endocrine abnormality that causes slipped capital femoral epiphysis (SCFE) has not been revealed. Recent studies have shown that parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] are involved in growth-plate chondrogenesis and matrix mineralization. Thus we examined in 13 patients with SCFE the serum levels of three immunoreactive forms of PTH (iPTH): the whole peptide [(1-84)PTH], the fragment containing the COOH-terminal portion (C-PTH), and the midportion (M-PTH). Additionally, serum levels of 25-hydroxyvitamin D [25-(OH)D] and 1,25-(OH)2D were measured. We found that the levels of M-PTH were significantly lower than those of controls, whereas levels of C-PTH and (1-84)PTH were not significantly different from those of controls. Similarly, levels of 1,25-(OH)2D were also significantly lower than control levels. In patients with initially low levels of M-PTH and 1,25-(OH)2D in whom the levels were monitored over a period, all levels returned to normal within a year after the onset of disease. The deficiency of M-PTH or 1,25-(OH)2D during the growth spurt could result in SCFE, although in this study, we cannot deny the possibility that the slippage may cause the deficiency.     

Evaluation of the AnaeroPack system for growth of anaerobic bacteria

Growth of anaerobic bacteria in the AnaeroPack (Mitsubishi Gas Chemical America, Inc., New York, N.Y.) anaerobic atmosphere generation systems, both the AnaeroPack jar and pouch and the AnaeroPack in a GasPak jar were considered equivalent to or better than growth obtained in the corresponding GasPak jar or pouch system (Becton Dickinson Microbiology Systems, Cockeysville, Md.) for 89 (86%) of the 103 anaerobes tested. There were a total of 26 discrepancies after 48 h of incubation, with 16 discrepancies unresolved after 96 h of incubation. The AnaeroPack jar and pouch never failed to reduce the anaerobic indicator. The AnaeroPack systems are easy to use and performed at least as well as or better than the BBL GasPak systems for growth of anaerobic bacteria.     

Mycobacterial growth and bacterial contamination in the mycobacteria growth indicator tube and BACTEC 460 culture systems

The BACTEC 460 system currently provides the most rapid detection of mycobacterial growth, but the system is radiometric and requires needles to inoculate specimens through the bottle's septum. The Mycobacteria Growth Indicator Tube (MGIT) system has a liquid medium, like the BACTEC system, and does not require needles when inoculating specimens. We compared mycobacterial growth from 510 specimens in the two systems. Average time to acid-fast bacillus (AFB) detection and identification to the species level was less with the BACTEC system, but this result was statistically significant only for AFB detection in specimens containing Mycobacterium avium-M. intracellulare complex. The contamination rate with MGIT was 29%; the BACTEC rate was 5%. To investigate MGIT contamination, we initiated a second study with changes in specimen processing. The MGIT contamination rate was reduced to 12%; the BACTEC rate was not significantly affected (5.5%). The most likely explanation for the contamination in MGIT is the richness of its medium compared to the BACTEC medium. Cost analysis for the two systems in a laboratory that processes 4,500 specimens a year is presented. The data suggest that the BACTEC 460 and the MGIT systems are approximately equivalent in cost and ability to support the growth of AFB. The MGIT system appears safer and easier to use and was preferred by laboratory personnel, but it cannot currently be used for blood specimens or antituberculosis susceptibility testing.     

The human homologue of yeast CRM1 is in a dynamic subcomplex with CAN/Nup214 and a novel nuclear pore component Nup88

The oncogenic nucleoporin CAN/Nup214 is essential in vertebrate cells. Its depletion results in defective nuclear protein import, inhibition of messenger RNA export and cell cycle arrest. We recently found that CAN associates with proteins of 88 and 112 kDa, which we have now cloned and characterized. The 88 kDa protein is a novel nuclear pore complex (NPC) component, which we have named Nup88. Depletion of CAN from the NPC results in concomitant loss of Nup88, indicating that the localization of Nup88 to the NPC is dependent on CAN binding. The 112 kDa protein is the human homologue of yeast CRM1, a protein known to be required for maintenance of correct chromosome structure. This human CRM1 (hCRM1) localized to the NPC as well as to the nucleoplasm. Nuclear overexpression of the FG-repeat region of CAN, containing its hCRM1-interaction domain, resulted in depletion of hCRM1 from the NPC. In CAN-/- mouse embryos lacking CAN, hCRM1 remained in the nuclear envelope, suggesting that this protein can also bind to other repeat-containing nucleoporins. Lastly, hCRM1 shares a domain of significant homology with importin-beta, a cytoplasmic transport factor that interacts with nucleoporin repeat regions. We propose that hCRM1 is a soluble nuclear transport factor that interacts with the NPC.     

Two types of intraoral distribution of fluorotic enamel

Assessment of body composition remains a goal for the routine assessment of nutritional status of patients on long-term dialysis. Methods generally available for estimation of body fat in healthy individuals are limited by practicality and availability for use in this patient population. Anthropometry, which is cost effective and easy to perform, is limited by the lack of appropriate reference standards for patients on dialysis and artifact caused by hydration status. Bioelectrical impedance affords new opportunities for non-invasive assessment of fluid volume, its distribution, and body cell mass; estimation of fat-free mass and body fat can be affected by hydration status. Dual x-ray absorptiometry permits estimation of bone status and fat mass because changes in hydration status are reflected in estimates of fat-free mass. Evaluation of validity of techniques for fluid status and body composition assessment requires the use of appropriate reference methods and proper statistical procedures to examine error, not only between groups, but by individual. Use of body composition assessment methods together with biochemical measurements will enhance the nutritional assessment of end-stage renal disease patients on long-term hemodialysis.     

Substantial narrowing of the Niemann-Pick C candidate interval by yeast artificial chromosome complementation

Niemann-Pick disease type C (NP-C) is an autosomal recessive lipidosis linked to chromosome 18q11-12, characterized by lysosomal accumulation of unesterified cholesterol and delayed induction of cholesterol-mediated homeostatic responses. This cellular phenotype is identifiable cytologically by filipin staining and biochemically by measurement of low-density lipoprotein-derived cholesterol esterification. The mutant Chinese hamster ovary cell line (CT60), which displays the NP-C cellular phenotype, was used as the recipient for a complementation assay after somatic cell fusions with normal and NP-C murine cells suggested that this Chinese hamster ovary cell line carries an alteration(s) in the hamster homolog(s) of NP-C. To narrow rapidly the candidate interval for NP-C, three overlapping yeast artificial chromosomes (YACs) spanning the 1 centimorgan human NP-C interval were introduced stably into CT60 cells and analyzed for correction of the cellular phenotype. Only YAC 911D5 complemented the NP-C phenotype, as evidenced by cytological and biochemical analyses, whereas no complementation was obtained from the other two YACs within the interval or from a YAC derived from chromosome 7. Fluorescent in situ hybridization indicated that YAC 911D5 was integrated at a single site per CT60 genome. These data substantially narrow the NP-C critical interval and should greatly simplify the identification of the gene responsible in mouse and man. This is the first demonstration of YAC complementation as a valuable adjunct strategy for positional cloning of a human gene.     

Significance of prosectorship and autopsies archives in the study of pulmonary tuberculosis pathology

The study revealed the pathomorphology of pulmonary tuberculosis by using abundant retrospective materials from the prosectorship's archives (1061 autopsies), which referred to individuals who had died from pulmonary tuberculosis in the pretreatment and treatment periods. The comparative analysis of autopsies in the populational context is an important method of this new medical line of pathoanatomical investigations.