Search

Internal carotid-artery stenosis (ICAS) causes complex and not yet well understood physiological impairments. We present preliminary data from an ongoing clinical study in ICAS patients and healthy, age-matched participants. The major aims were to evaluate the reliability of a multimodal MRI-protocol and investigate physiological changes. For ICAS patients, regionally impaired vascular-reactivity as well as hypo-perfusion were found. In accordance with literature, we did not find ICAS-induced changes in oxygen extraction on group level. The presented preliminary results thus imply successful application of multimodal MRI methods and are highly promising with respect to gaining a deeper insight into ICAS-related physiological changes.

Novel hydroxy-functionalized phosphabenzenes were synthesized, which provide the possibility to prepare chiral phosphabenzene–phosphites. These systems act as bidentate ligands toward rhodium centers and the corresponding metal complexes were applied in the rhodium-catalyzed asymmetric hydrogenation of prochiral substrates.

This article describes the synthesis and binding properties of highly selective noncovalent molecular receptors 1(3).(DEB)6 and 3(3).(DEB)6 for different hydroxyl functionalized anthraquinones 2. These receptors are formed by the self-assembly of three calix[4]arene dimelamine derivative molecules (1 or 3) and six diethylbarbiturate (DEB) molecules to give 1(3).(DEB)6 or 3(3).(DEB)6. Encapsulation of 2 occurs in a highly organized manner; that is, a noncovalent hydrogen-bonded trimer of 2 is formed within the hydrogen-bonded receptors 1(3).(DEB)6 and 3(3).(DEB)6. Both receptors 1(3).(DEB)6 and 3(3).(DEB)6 change conformation from staggered to eclipsed upon complexation to afford a better fit for the 2(3) trimer. The receptor selectivity toward different anthraquinone derivatives 2 has been studied using 1H NMR spectroscopy, X-ray crystallography, UV spectroscopy, and isothermal microcalorimetry (ITC). The pi-pi stacking between the electron-deficient center ring of the anthraquinone derivatives 2a-c and 2e-g and the relatively electron-poor melamine units of the receptor is the driving force for the encapsulation of the guest molecules. The selectivity of the hydrogen-bonded host for the anthraquinone derivatives is the result of steric interactions between the guest molecules and the calix[4]arene aromatic rings of the host.

Purpose: To test at 1.5 T whether T1 rho magnetic resonance (MR) imaging of fibrotic liver disease is feasible, to investigate whether liver T1 rho imaging allows assessment of the severity of liver cirrhosis, and to assess the normal liver T1 rho range in healthy patients. Materials and Methods: This prospective study was approved by the institutional ethics committee. Written informed consent was obtained. Healthy volunteers (n = 25) and patients (n = 34) with cirrhosis underwent whole-liver T1 rho MR imaging at 1.5 T. Mean T1 rho values were calculated from liver regions of interest. Mean T1r values were correlated to clinical data and histopathologic analysis by analysis of variance. Receiver operating characteristic curves were calculated to determine the accuracy of mean T1 rho values for the assessment of Child-Pugh class. Results: Mean T1 rho values of volunteers (mean, 40.9 msec +/- 2.9 [ standard deviation]; range, 33.9-46.3 msec) were significantly lower than those of patients who were Child-Pugh class A (P

The chiral centres in the dilactone moiety of the title compound, C13H14O5, are in the configuration 3S,6R. The ring itself has a somewhat flattened twist-boat conformation. C—H⋯O inter­actions join the mol­ecules into a two-dimensional network running parallel to the (101) plane.

Contains fulltext : 10228.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 10120.pdf (Publisher’s version ) (Open Access)

The effectiveness of an extractive distillation process relies on the choice of the extractive solvent. The conventional methodology to select solvents is based on Group Contribution Methods. Ionic liquids have shown several advantages over conventional solvents used in extractive distillation and liquid-liquid extraction processes. However, there is no existing methodology to select ILs as solvents for ED processes due to the lack of experimental data, their low capacity and unavailability of group contribution parameters for most IL systems. The objective of this work is to establish a systematic solvent selection methodology for ED processes for the separation of aromatics/non-aromatics mixtures employing ionic liquids.

Traditionally polyester production is done in a batch reactor equipped with a separation column for batch distillation. A promising alternative for the intensification of this process is reactive distillation. In this paper, a reactive distillation model is developed for the synthesis of an unsaturated polyester process. The simulation results are compared with the industrial batch reactor output data of the product. It is found that the model predicts the polymer attribute, isomerisation and saturation composition of the polymer in the range of industrial unsaturated polyester production. Industrial unsaturated polyester production time is around 12 hours. However, the simulation study shows that the total production time of unsaturated polyester in a continuous reactive distillation system is between 1.5 hours to 2 hours for the same product quality as during batch production. The equilibrium conversion is also raised by 7% compared to the conventional process. The model demonstrated that reactive distillation has the potential to intensify the process by factor of 6 to 8 in comparison to the batch reactor.

The distillation of ethylbenzene (EB) from styrene (SM) is very energy intensive. By using extractive distillation instead, both capital and energy expenses are potentially reduced dramatically. Hereto we propose to use sulfolane (SF) as solvent. Currently there is no ternary vapor liquid equilibrium (VLE) data available of the system SM/EB/SF and the binary VLE data sets of EB/SM available in literature are found to be thermodynamically inconsistent. In this study thermodynamically consistent VLE data is obtained for the three binary systems and the ternary system in the pressure range of 50-200 mbar. Both the Wilson and NRTL model can adequately describe the experimental VLE data. The solvent SF increases the relative volatility significantly from 1.3-1.4 up to 2.3. Equilibrium process modeling suggests that an energy reduction of 50% compared to the traditional distillation process can be obtained with the extractive distillation process.

The mass transfer efficiency of an extractive distillation column was compared for the ionic liquid 1-Ethyl-3-methylimidazolium ethyl sulfate and ethylene glycol as solvents for the separation of water-ethanol. A rate based model was established in ASPEN Plus. Tray efficiency profiles along the column showed a reduction in mass transfer performance when the ionic liquid was used due to its relatively high viscosity. Indeed, this reduction was more pronounced when the liquid phase viscosity was increased by means of a higher solvent-to-feed ratio. Finally, a sharp decline in efficiency was observed at high liquid phase viscosities, approaching the flooding point.

In this paper conceptual designs for the esterification of myristic acid with isopropanol through reactive distillation (packed and tray column) and bubble column are constructed, which are evaluated against the batch process based on required reaction volumes. The required reactor volume can be decreased with 27 or 79 %, allowing a maximum temperature of respectively 170 and 220°C, using a packed reactive distillation column. Using a tray reactive distillation column and a maximum temperature of 220°C, the required reactor volume can be decreased with 93 %. Due to the less favourable mass transfer characteristics of the bubble column, in here the required reactor volume can only be decreased with 78%. When a temperature of 220°C is allowed in the column, the tray reactive distillation is the preferable process for the esterification of myristic acid isopropanol, based on the required reaction volumes. The influence of the maximum column temperature and the influence of a larger liquid hold-up per stage as a result of a different column configuration are of equal importance for the required reaction volume.