Pemodelan dan Simulasi Proses Adsorpsi Gas Pengotor oleh Molecular Sieve pada Pendingin Rde dengan Software Chemcad

The purity of RDE10 helium coolant should be maintained from various impurities gas due to water/air ingress that reacts with the reflector graphite (C). These impurities are CH4, CO, CO2, H2O, H2, O2, and N2 which can initiate oxidation corrosion or carburization-decarburization so the concentration should be maintain to be a minimum. The helium coolant is purified by Helium Purification System (HPS). One of the stages in HPS is adsorption by Molecular Sieve mainly for CO2 and H2O molecules. This paper discusses the influence of pressure, known as pressure swing adsorption (PSA) on the adsorption ability of the Molecular Sieve aims to determine the most effective pressure that will be operated on Molecular Sieve column. Molecular Sieve is modeled with CHEMCAD computer code in two columns, one column for the adsorption process, and the other for the regeneration (desorption). Adsorption methods used in the analysis is the Langmuir method. Models that have been developed simulated by providing input: total flow rate of 10.5 kg/hour, 30 °C, porosity 0.7, bed height 2 m, pore diameter 5 A, and the amount of O2 and N2 impurities respective each 1 g/s. The pressure varies between 5 to 50 bars, and the Molecular Sieve adsorption capability is analyzed. Simulation results show that with the increase in pressure of 5 to 50 bar, indicating an increase in Molecular Sieve absorption capacity to CO2 is 15.90% and to H2O is 15.80%. In the SPH design, the input stream to the Molecular Sieve must be compressed until 50 bar to obtain high absorption capability of the CO2 and H2O.

Phormidiumphycoerythrin forms hexamers in crystals: a crystallographic study

The crystallographic analysis of a marine cyanobacterium (Phormidiumsp. A09DM) phycoerythrin (PE) that shows distinct sequence features compared with known PE structures from cyanobacteria and red algae is reported.PhormidiumPE was crystallized using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Diffraction data were collected on the protein crystallography beamline at the Indus-2 synchrotron. The crystals diffracted to about 2.1 Å resolution at 100 K. The crystals, with an apparent hexagonal morphology, belonged to space groupP1, with unit-cell parametersa= 108.3,b= 108.4 Å,c= 116.6 Å, α = 78.94, β = 82.50, γ = 60.34°. The molecular-replacement solution confirmed the presence of 12 αβ monomers in theP1 cell. ThePhormidiumPE elutes as an (αβ)3trimer of αβ monomers from a molecular-sieve column and exists as [(αβ)3]2hexamers in the crystal lattice. Unlike red algal PE proteins, the hexamers ofPhormidiumPE do not form higher-order structures in the crystals. The existence of only one characteristic visual absorption band at 564 nm suggests the presence of phycoerythrobilin chromophores, and the absence of any other types of bilins, in thePhormidiumPE assembly.

The breakthrough curve combination for xenon sampling dynamics in a carbon molecular sieve column

In the research of xenon sampling and xenon measurements, the xenon breakthrough curve plays a significant role in the xenon concentrating dynamics.

The potential of various lipopolysaccharides to release IL-8 and G-CSF

Lipopolysaccharide (LPS) derived from Pseudomonas aeruginosa is less cytotoxic than that from Escherichia coli. But P. aeruginosa induces a prominent sustained lung inflammation as in cystic fibrosis and diffuse panbronchiolotis. The present study examined the potential for several LPSs obtained from E. coli and P. aeruginosa to release neutrophil chemotactic activity (NCA) from lung cells. LPSs differently stimulated A549 cells, BEAS-2B cells, and lung fibroblasts to release NCA [ P. aeruginosa > E. coli 0127:B8 (Difco) > E. coli 055:B5 (Sigma) > E. coli 026:B6 (Sigma)]. E. coli 0127:B8 (Sigma) and 0111:B4 (Sigma) did not stimulate these cells. NCA was chemotactic by checkerboard analysis. Molecular-sieve column chromatography revealed three chemotactic peaks. The release of NCA was inhibited by cycloheximide and lipoxygenase inhibitors. Experiments with blocking antibodies suggested that much of the NCA was secondary to the release of interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF). Thus we examined the concentrations of IL-8 and G-CSF and found that the potency of the various LPSs to stimulate NCA closely paralleled the potency in releasing IL-8 and G-CSF. But a difference among LPSs to stimulate A549 cells was observed. Finally, the release of IL-6 showed similar results. These data suggest that P. aeruginosa LPS may stimulate lung cells to release more NCA than E. coli LPSs, leading to sustained lung inflammation.

Human lung fibroblasts release chemokinetic activity for monocytes constitutively

We determined whether human lung fibroblasts (HLFs) might release mediators that are responsible for monocyte chemokinetic activity (MCA) constitutively. HLF supernatant fluids showed MCA in a time-dependent manner ( P < 0.001). Checkerboard analysis of 24- and 72-h supernatant fluids showed that the activity was chemokinetic. Partial characterization of 24- and 72-h supernatant fluids revealed that the mediators released after 24 h were predominantly composed of lipid-soluble activity, and MCA was blocked by lipoxygenase inhibitors. The mediators released after 72 h were predominantly trypsin sensitive and blocked by cycloheximide. Molecular-sieve column chromatography identified four peaks of MCA. A polyclonal antibody to monocyte chemoattractant protein-1 (MCP-1) inhibited MCA by 20% after 24 h and by 40% after 72 h. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-β (TGF-β) antibodies attenuated MCA released after 72 h by 30 and 10%, respectively. These antibodies inhibited corresponding molecular-weight peaks separated by molecular-sieve column. The concentrations of MCP-1, GM-CSF, and TGF-β were 4,698 ± 242, 26.8 ± 3.8, and 550 ± 15 pg/ml, respectively. A leukotriene B4(LTB4)-receptor antagonist attenuated the total MCA and the lowest molecular weight peak of MCA. The concentrations of LTB4were 153.4 ± 12.4 (24 h) and 212 ± 16.6 (72 h) pg/ml. These findings suggest that HLFs may modulate the recruitment of monocytes into the lung by releasing MCP-1, GM-CSF, TGF-β, and LTB4constitutively.

Acetylcholine stimulates alveolar macrophages to release inflammatory cell chemotactic activity

Neurological transmitters including ACh, substance P (SP), and calcitonin gene-related peptide (CGRP) play an important role in regulating airway tone, and increased bronchial reactivity to cholinergic stimulation is a well-recognized phenomenon in patients with bronchial asthma. We postulated that ACh, SP, and CGRP might stimulate alveolar macrophages (AMs) to release neutrophil, monocyte, and eosinophil chemotactic activities. To test this hypothesis, bovine AMs were isolated by bronchoalveolar lavage and cultured. AMs released chemotactic activities in response to ACh in a dose- and time-dependent manner ( P < 0.05). However, SP and CGRP did not stimulate bovine AMs. Checkerboard analysis revealed that these released activities were predominantly chemotactic. Partial characterization and molecular-sieve column chromatography revealed that low-molecular-weight lipid-soluble activity was predominant. Lipoxygenase inhibitors significantly blocked the release of chemotactic activities ( P < 0.05). Leukotriene B4- and platelet-activating factor-receptor antagonists blocked the chemotactic activities. Immunoreactive leukotriene B4 significantly increased in supernatant fluids in response to ACh ( P < 0.05), but platelet-activating factor did not. The receptor responsible for the release of the chemotactic activities was the muscarinic M3 receptor. These data demonstrate that ACh stimulates AMs to release lipoxygenase-derived chemotactic activities and plays a role in inflammatory cell recruitment into the airway.

Rat epididymal luminal fluid acid β-d-galactosidase optimally hydrolyses glycoprotein substrate at neutral pH

Several glycosidases, purified and characterized from mammalian tissues, have been shown to be optimally active under acidic conditions when p-nitrophenyl (PNP) or 4-methylumbelliferyl glycosides are used as substrates. Although high levels of the glycosidases are present in the epididymal lumen, their physiological role remains uncertain. To be functional, the glycosidases are expected to be enzymatically active at or near the physiological pH of luminal fluid. In this report, we demonstrate that the rat epididymal luminal fluid beta-D-galactosidase, optimally active toward PNP beta-D-galactoside at pH 3.5, shows maximum activity towards a glycoprotein substrate ([Gal-3H]fetuin) at neutral pH. Several lines of evidence, including immunoprecipitation studies using antibody to the acid beta-D-galactosidase, and substrate competition studies, indicate that PNP galactosidase and [3H]Gal galactosidase activities are caused by a single enzyme, and that the two substrates are probably cleaved by the same catalytic site(s). Competition studies with various disaccharides indicate that this enzyme is capable of cleaving a variety of galactose linkages found in both O- and N-linked oligosaccharides. Molecular-sieve column chromatography of the beta-D-galactosidase of luminal fluid under several conditions of buffer and pH show that, whereas the enzyme eluted as a tetramer (apparent M(r) 320,000) under acidic conditions (pH 3.5-4.3), only dimers and monomers (apparent M(r) 180,000 and 92,000 respectively) were observed in neutral conditions (pH 6.8). This aggregation/dissociation phenomenon is reversible. These studies indicate that beta-D-galactosidase is present in the luminal fluid in dissociated forms, and is therefore optimally active towards glycoprotein substrates at physiological pH. The potential role of the enzyme in modification of sperm surface glycoproteins is discussed.