Modeling of continuous slug flow cooling crystallization towards pharmaceutical applications

The rising trend towards continuous production in the field of small-scale crystallization has generated many creative concepts for apparatuses for the production of active pharmaceutical ingredients. One of these promising apparatuses is the Slug Flow Crystallizer (SFC), which enables the adjustment of the particle size distribution and the achievement of high yields through its alternating slug flow. To realize and understand the crystallization inside the SFC, high experimental effort has been necessary until now. Therefore, a mechanistic model considering the hydrodynamics of slug flow, the energy and mass balances, and the crystallization phenomena of growth and agglomeration inside the apparatus was developed. Its purpose is to improve the understanding of the process, estimate the effects of operating parameters on target properties, and predict crystallization behavior for different substance systems with minimal experimental effort. Successful modeling was validated with experimental results for the substance system l-alanine/water. Furthermore, the robustness of the model was evaluated, and guidelines were presented, enabling the transfer of the model to new substance systems

Group Spinner : recognizing and visualizing learning in the classroom for reflection, communication, and planning

Group Spinner is a digital visual tool intended to help teachers observe and reflect on children’s collaborative technology-enhanced learning activities in the classroom. We describe the design of Group Spinner, which was informed by activity theory, previous work and teachers’ focus group feedback. Based on a radar chart and a set of indicators, Group Spinner allows teachers to record in-class observations as to different aspects of group learning and learning behaviors, beyond the limited knowledge acquisition measures. Our exploratory study involved 6 teachers who used the tool for a total of 23 classes in subjects ranging from Maths and Geography to Sociology and Art. Semi-structured interviews with these teachers revealed a number of different uses of the tool. Depending on their experience and pedagogy, teachers considered Group Spinner to be a valuable tool to support awareness, reflection, communication, and/or planning

Nuevos productos electrónicos para 2005

Sección: La RedSiguiendo la línea que el CSIC inició hace tiempo de ir ampliando su oferta de recursos electrónicos en la medida de lo posible cada año, se han suscrito por primera vez en 2005.N

Molecular Ultrasound Imaging of Junctional Adhesion Molecule A Depicts Acute Alterations in Blood Flow and Early Endothelial Dysregulation

Objective: The junctional adhesion molecule A (JAM-A) is physiologically located in interendothelial tight junctions and focally redistributes to the luminal surface of blood vessels under abnormal shear and flow conditions accompanying atherosclerotic lesion development. Therefore, JAM-A was evaluated as a target for molecularly targeted ultrasound imaging of transient endothelial dysfunction under acute blood flow variations. Approach and Results: Flow-dependent endothelial dysfunction was induced in apolipoprotein E-deficient mice (n=43) by carotid partial ligation. JAM-A expression was investigated by molecular ultrasound using antibody-targeted poly(n-butyl cyanoacrylate) microbubbles and validated with immunofluorescence. Flow disturbance and arterial remodeling were assessed using functional ultrasound. Partial ligation led to an immediate drop in perfusion at the ligated side and a direct compensatory increase at the contralateral side. This was accompanied by a strongly increased JAM-A expression and JAM-A-targeted microbubbles binding at the partially ligated side and by a moderate and temporary increase in the contralateral artery (approximate to 14x [P<0.001] and approximate to 5x [P<0.001] higher than control, respectively), both peaking after 2 weeks. Subsequently, although JAM-A expression and JAM-A-targeted microbubbles binding persisted at a higher level at the partially ligated side, it completely normalized within 4 weeks at the contralateral side. Conclusions: Temporary blood flow variations induce endothelial rearrangement of JAM-A, which can be visualized using JAM-A-targeted microbubbles. Thus, JAM-A may be considered as a marker of acute endothelial activation and dysfunction. Its imaging may facilitate the early detection of cardiovascular risk areas, and it enables the therapeutic prevention of their progression toward an irreversible pathological state

The Tully-Fisher Relation in Cluster Cl0024+1654 at z=0.4

Using moderate-resolution Keck spectra, we have examined the velocity profiles of 15 members of cluster Cl0024+1654 at z=0.4. WFPC2 images of the cluster members have been used to determine structural parameters, including disk sizes, orientations, and inclinations. We compare two methods of optical rotation curve analysis for kinematic measurements. Both methods take seeing, slit size and orientation, and instrumental effects into account and yield similar rotation velocity measurements. Four of the galaxies in our sample exhibit unusual kinematic signatures, such as non-circular motions. Our key result is that the Cl0024 galaxies are marginally underluminous (0.50 +/- 0.23 mag), given their rotation velocities, as compared to the local Tully-Fisher relation. In this analysis, we assume no slope evolution, and take into account systematic differences between local and distant velocity and luminosity measurements. Our result is particularly striking considering the Cl0024 members have very strong emission lines, and local galaxies with similar Halpha equivalent widths tend to be overluminous on the Tully-Fisher relation. Cl0024 Tully-Fisher residuals appear to be correlated most strongly with galaxy rotation velocities, indicating a possible change in the slope of the Tully-Fisher relation. However, we caution that this result may be strongly affected by magnitude selection and by the original slope assumed for the analysis. Cl0024 residuals also depend weakly on color, emission line strength and extent, and photometric asymmetry. In a comparison of stellar and gas motions in two Cl0024 members, we find no evidence for counter-rotating stars and gas, an expected signature of mergers.Comment: 38 pages, 10 figures, accepted for publication in ApJ; version with full-resolution figures can be downloaded from http://www.ucolick.org/~anne/recent_pubs.htm

The shape of the dark matter halo in the early-type galaxy NGC 2974

We present HI observations of the elliptical galaxy NGC 2974, obtained with the Very Large Array. These observations reveal that the previously detected HI disc in this galaxy (Kim et al. 1988) is in fact a ring. By studying the harmonic expansion of the velocity field along the ring, we constrain the elongation of the halo and find that the underlying gravitational potential is consistent with an axisymmetric shape. We construct mass models of NGC 2974 by combining the HI rotation curve with the central kinematics of the ionised gas, obtained with the integral-field spectrograph SAURON. We introduce a new way of correcting the observed velocities of the ionised gas for asymmetric drift, and hereby disentangle the random motions of the gas caused by gravitational interaction from those caused by turbulence. To reproduce the observed flat rotation curve of the HI gas, we need to include a dark halo in our mass models. A pseudo-isothermal sphere provides the best model to fit our data, but we also tested an NFW halo and Modified Newtonian Dynamics (MOND), which fit the data marginally worse. The mass-to-light ratio M/L_I increases in NGC 2974 from 4.3 (M/L_I)sun at one effective radius to 8.5 (M/L_I)sun at 5 Re. This increase of M/L already suggests the presence of dark matter: we find that within 5 Re at least 55 per cent of the total mass is dark.Comment: 17 pages, 20 figures, accepted by MNRA