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Dominant Structures (dominant + structure)
Selected AbstractsA Short Note About Energy-Efficiency Performance of Thermally Coupled Distillation SequencesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2006Juan Gabriel Segovia-Hernández Abstract In this work, we present a comparative study of the energy-efficiency performance between conventional distillation sequences and thermally coupled distillation arrangements (TCDS) for the separation of ternary mixtures of hydrocarbons under the action of feedback control loops. The influence of the relative ease of separation of the feed mixture and its composition was analyzed. The feedback analysis was conducted through servo tests with individual changes in the set points for each of the three product streams. Standard PI controllers were used for each loop. The results show an apparent trend regarding the sequence with a better dynamic performance. Generally, TCDS options performed better for the control of the extreme components of the ternary mixture (A and C), while the conventional sequences offered a better dynamic behaviour for the control of the intermediate component (B). The only case in which there was a dominant structure for all control loops was when the feed contained low amounts of the intermediate component and the mixture had similar relative volatilities. The Petlyuk column provided the optimal choice in such case, which contradicts the general expectations regarding its control behaviour. In addition, the energy demands during the dynamic responses were significantly lower than those observed for the other distillation sequences. TCDS options, therefore, are not only more energy efficient than the conventional sequences, but there are cases in which they also offer better feedback control properties. On présente dans ce travail une étude comparative de la performance d'efficacité d'énergétique entre les séquences de distillation conventionnelles et les configurations de distillation couplées thermiquement (TCDS) pour la séparation de mélanges ternaires d'hydrocarbures sous l'action de boucles de contrôle d'asservissement. L'influence de la facilité relative de séparation du mélange d'alimentation et de sa composition est analysée. L'analyse de rétroalimentation est réalisée grâce à des tests d'asservissement avec des changements individuels dans les points de consigne pour chacun des trois courants de produits. Des contrôleurs PI standards ont été utilisés pour chaque boucle. Les résultats montrent une tendance apparente pour la séquence ayant une meilleure performance dynamique. Généralement, les options TCDS sont meilleures pour le contrôle des composantes extrêmes du mélange ternaire (A et C), tandis que les séquences conventionnelles offrent un meilleur contrôle dynamique pour le contrôle de la composante intermédiaire (B). Le seul cas où il y a une structure dominante pour toutes les boucles de contrôle, c'est lorsque l'alimentation contenant de faibles quantités de la composante intermédiaire et le mélange ont la même volatilité relative. La colonne Petlyuk est le choix optimal dans un tel cas, ce qui contredit les attentes générales concernant son comportement de contrôle. En outre, les demandes d'énergie pendant les réponses dynamiques sont significativement plus faibles que celles observées pour les autres séquences de distillation. Ainsi, non seulement les options TCDS sont plus efficaces que les séquences conventionnelles, mais il y a des cas où elles offrent également de meilleures propriétés de contrôle d'asservissement. [source] Design of an FIR filter for the displacement reconstruction using measured acceleration in low-frequency dominant structuresINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2010Hae Sung Lee Abstract This paper presents a new class of displacement reconstruction scheme using only acceleration measured from a structure. For a given set of acceleration data, the reconstruction problem is formulated as a boundary value problem in which the acceleration is approximated by the second-order central finite difference of displacement. The displacement is reconstructed by minimizing the least-squared errors between measured and approximated acceleration within a finite time interval. An overlapping time window is introduced to improve the accuracy of the reconstructed displacement. The displacement reconstruction problem becomes ill-posed because the boundary conditions at both ends of each time window are not known a priori. Furthermore, random noise in measured acceleration causes physically inadmissible errors in the reconstructed displacement. A Tikhonov regularization scheme is adopted to alleviate the ill-posedness. It is shown that the proposed method is equivalent to an FIR filter designed in the time domain. The fundamental characteristics of the proposed method are presented in the frequency domain using the transfer function and the accuracy function. The validity of the proposed method is demonstrated by a numerical example, a laboratory experiment and a field test. Copyright © 2009 John Wiley & Sons, Ltd. [source] Glycosylation status of haptoglobin in sera of patients with prostate cancer vs. benign prostate disease or normal subjectsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2008Tsutomu Fujimura Abstract We studied chemical level and glycosylation status of haptoglobin in sera of patients with prostate cancer, as compared to benign prostate disease and normal subjects, with the following results. (i) Haptoglobin level was enhanced significantly in sera of prostate cancer. (ii) Sialylated bi-antennary glycans were the dominant structures in haptoglobins from all 3 sources, regardless of different site of N-linked glycan. The N-linked glycans at N184 were exclusively bi-antennary, and showed no difference between prostate cancer vs. benign prostate disease. (iii) Tri-antennary, N-linked, fucosylated glycans, carrying at least 1 sialyl-Lewisx/a antenna, were predominantly located on N207 or N211 within the amino acid 203-215 sequence of the ,-chain of prostate cancer, and were minimal in benign prostate disease. Fucosylated glycans were not observed in normal subjects. A minor tri-antennary N-linked glycan was observed at N241 of the ,-chain in prostate cancer, which was absent in benign prostate disease. (iv) None of these N-linked structures showed the expected presence of disialylated antennae with GalNAc,4(NeuAc,3)Gal,3(NeuAc,6)GlcNAc,Gal, or its analogue, despite cross-reactivity of prostate cancer haptoglobin with monoclonal antibody RM2. (v) Minor levels of O -glycosylation were identified in prostate cancer haptoglobin for the first time. Mono- and disialyl core Type 1 O-linked structures were identified after reductive ,-elimination followed by methylation and mass spectrometric analysis. No evidence was found for the presence of specific RM2 or other tumor-associated glycosyl epitopes linked to this O -glycan core. In summary, levels of haptoglobin are enhanced in sera of prostate cancer patients, and the N -glycans attached to a defined peptide region of its ,-chain are characterized by enhanced branching as well as antenna fucosylation. © 2007 Wiley-Liss, Inc. [source] Temperature and urea induced denaturation of the TRP-cage mini protein TC5b: A simulation study consistent with experimental observationsPROTEIN SCIENCE, Issue 10 2009Z. Gattin Abstract The effects of temperature and urea denaturation (6M urea) on the dominant structures of the 20-residue Trp-cage mini-protein TC5b are investigated by molecular dynamics simulations of the protein at different temperatures in aqueous and in 6M urea solution using explicit solvent degrees of freedom and the GROMOS force-field parameter set 45A3. In aqueous solution at 278 K, TC5b is stable throughout the 20 ns of MD simulation and the trajectory structures largely agree with the NMR-NOE atom,atom distance data available. Raising the temperature to 360 K and to 400 K, the protein denatures within 22 ns and 3 ns, showing that the denaturation temperature is well below 360 K using the GROMOS force field. This is 40,90 K lower than the denaturation temperatures observed in simulations using other much used protein force fields. As the experimental denaturation temperature is about 315 K, the GROMOS force field appears not to overstabilize TC5b, as other force fields and the use of continuum solvation models seem to do. This feature may directly stem from the GROMOS force-field parameter calibration protocol, which primarily involves reproduction of condensed phase thermodynamic quantities such as energies, densities, and solvation free energies of small compounds representative for protein fragments. By adding 6M urea to the solution, the onset of denaturation is observed in the simulation, but is too slow to observe a particular side-chain side-chain contact (Trp6-Ile4) that was experimentally observed to be characteristic for the denatured state. Interestingly, using temperature denaturation, the process is accelerated and the experimental data are reproduced. [source] Rheological characterization of schizophyllan aqueous solutions after denaturation,renaturation treatmentBIOPOLYMERS, Issue 4 2004Yapeng Fang Abstract Schizophyllan (SPG) with a molecular weight of 2.6×106, designated SPG-1, is denatured and then renatured at a concentration of 1.8 wt % by alkalization,neutralization. The prepared denatured,renatured samples (DRSPG-1) are diluted to various concentrations and equilibrated for 10 days before rheological and intrinsic viscosity measurements. When concentration (Cp) is above 0.75 wt %, DRSPG-1 aqueous systems have weak gel-type rheological properties. However, for 0.28 wt % , Cp , 0.65 wt % and Cp , 0.19 wt %, DRSPG-1 aqueous systems behave as power law fluids and Newtonian fluids, respectively, which are attributed to the moderate isotropy degree of DRSPG-1 chains. Furthermore, a critical overlap parameter of c*[,] = 1.2 is determined for DRSPG-1 in aqueous solutions, which is close to that of 1 for intact SPG in water while far smaller than that of 4.3 for SPG in DMSO. This is considered to be due to the strong interactions of DRSPG-1 chains in water, further confirmed by the intrinsic viscosity measurements in which the DRSPG-1 aqueous solution shows an abnormally large value of Huggins constant. Regarding the structure of DRSPG-1 weak gels, multiruns of dynamic strain sweep measurements suggest that the dominant structures are aggregates formed by hydrogen-bonding associations of DRSPG-1 chains rather than the permanent three-dimensional network. In addition, the step-shear rate tests are performed to study the thixotropic properties of DRSPG-1 aqueous systems. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004 [source] The applied anatomy of anterior approach for minimally invasive hip joint surgeryCLINICAL ANATOMY, Issue 2 2009Li Hua Chen Abstract The anterior approach for minimally invasive hip joint surgery is one of the common approaches utilized in hip joint surgery. Here, we report the results of dissections in 60 sides of human adult cadavers. We observed and measured the branches of the superficial circumflex iliac artery, the lateral femoral cutaneous nerves, the lateral circumflex femoral artery, and the superior gluteal nerves in the experiment via the anterior approach for minimally invasive hip joint surgery. The relationship between these structures and the anterior approach was studied. The present study provides important data demonstrating the location, path of dominant structures that might be encountered during the surgery and their relationships with the surgical incision. These data may allow surgeons performing the anterior approach for hip joint surgery to minimize the risk of neurovascular injury. Clin. Anat. 22:250,255, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||