Development of a Continuous Segmented Flow Tubular Reactor and the “Scale‐out” Concept – In Search of Perfect Powders

The synthesis of powders with controlled shape and narrow particle size distributions is still a major challenge for many industries. A continuous Segmented Flow Tubular Reactor (SFTR) has been developed to overcome homogeneity and scale‐up problems encountered when using batch reactors. Supersaturation is created by mixing the co‐reactants in a micromixer inducing precipitation; the suspension is then segmented into identical micro‐volumes by a non‐miscible fluid and sent through a tube. These micro‐volumes are more homogeneous when compared to large batch reactors leading to narrower size distributions, better particle morphology, polymorph selectivity and stoichiometry. All these features have been demonstrated on single tube SFTR for different chemical systems. To increase productivity for commercial application the SFTR is being “scaled‐out” by multiplying the number of tubes running in parallel instead of scaling‐up by increasing their size. The versatility of the multi‐tube unit will allow changes in type of precipitate with a minimum of new investment as new chemistry can be researched, developed and optimised in a single tube SFTR and then transferred to the multi‐tube unit for powder production.     

Is there a direct relationship between oral astringency and human salivary protein binding?

For decades, it is believed that astringency is due to the polyphenol-induced complexation of proline-rich salivary proteins in the oral cavity. In order to compare for the first time the human sensory threshold concentrations and the salivary protein binding activity of a series of astringent stimuli, human saliva protein was incubated for 5 min at 37 °C in the presence of astringent food-derived compounds and, after micro-centrifugation, the amount of the target molecules in the supernatant was quantitatively determined by HPLC-UV/Vis. Significant protein binding was observed for (−)-epigallocatechin-3-gallate, (−)-gallocatechin-3-gallate, (+)-gallocatechin, and (−)-catechin-3-gallate, all of which containing at least one galloyl moiety in the molecule and exhibiting rather high sensory thresholds of more than 200 μmol/L. In comparison, (+)-catechin and procyanidin B2, both lacking in any galloyl function, showed only comparatively low binding activity and, most interestingly, quercetin-3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside and 3-carboxymethyl-indole-1-N-β-d-glucopyranoside did not show any protein binding at all, although the later N- and O-glycosides exhibited extraordinarily low sensory threshold concentrations of less than 0.001 and 0.0003 μmol/L, respectively. The data give some first evidence that the quantity of the non-bound, “free” astringent stimulus in the saliva liquid might be more closely related to the sensory perception of astringency than the amount complexed or precipitated by proteins. It is therefore questionable as to whether oral perception of astringency is related to the complexation and/or precipitation of salivary proteins.     

Use of cell ELISA for the screening of neurotrophic activities on minor cell populations in retinal monolayer cultures

BACKGROUND: Whereas the secretion of the male vesicular gland in most mammals is amorphous, that of the tree shrew, Tupaia glis, was observed to be stored as globules. METHODS: Vesicular and prostate glands from Tupaia, fixed in glutaraldehyde and osmium, were studied in the light and electron microscopes. Other materials considered included the Tupaia ejaculate produced by electroejaculation and, for comparative purposes, sections of the vesicular gland from a dermopteran, the flying lemur. RESULTS: The vesicular gland epithelium in Tupaia secretes small granular aggregates and occasionally a denser aggregate that is associated with cells having obvious apical Golgi lamellae. In the alveolar lumen, these aggregates unite with others to form, respectively, granular and some dense globules of up to approximately 15 mu in diameter, which appear as such in semen produced by electroejaculation. In contrast to the prostate, however, precursor secretion vesicles were rare in the vesicular epithelium. Although poorly fixed, the vesicular gland secretion from a flying lemur also appeared to form globules. CONCLUSIONS: Although it is unlike the homogeneous secretion elaborated in most mammals, including primates and insectivores, the globular product of the Tupaia vesicular gland seems comparable to that in a variety of mega- and microbats, among representative species of which it appears to provide the bulk material for the vaginal copulation plug. Because a museum specimen examined here also indicates its occurrence in a flying lemur, the globular vesicular gland secretion common to Tupaiidae, to at least some Mega- and Microchiroptera, and apparently to Dermoptera may provide a soft tissue feature of some value in the cladistic approach to phylogenetic reconstruction within the Archonta. Anat.     

Electro-optic sampling system for the testing of high-speedintegrated circuits using a free running solid-state laser

This paper deals with the indirect electro-optic sampling technique for the low-invasive detection of periodical voltage waveforms on lines in high-speed integrated circuits. The system introduced here is based on a passive mode-coupled Ti:Sapphire-Laser as light source for generating optical pulses in the subpicosecond regime. Therefore, we have to synchronize the resulting electric measurement signal and its external trigger onto the pulse repetition rate of this free running solid-state laser. The multi user function of the laser system forces us to transmit the pulses via a single-mode fiber into the measurement setup. For that purpose we developed a special optical arrangement to minimize the widening of the pulses in the time domain. The system's high-temporal resolution of nearly 10 ps in combination with its high-voltage sensitivity of about 800 μV/√(Hz) is demonstrated by measurements of an integrated microwave frequency divider     

The distribution of HBV, HCV and HGV among livers with fulminant hepatic failure of different aetiology

BACKGROUND/AIMS: The aim of the study was to assess the impact factor of HCV and HGV in fulminant hepatic failure. METHODS: The 5'-untranslated regions of HCV RNA and HGV RNA and a segment of the core antigen sequence of HBV were amplified after extracting the nucleic acids from snap-frozen tissue aliquots from explanted livers of 26 consecutive patients undergoing orthotopic liver transplantation for fulminant hepatic failure preoperatively diagnosed as either autoimmune (n=2), HAV/HBV (n=8), toxic (n=4) or aetiologically unknown (n=12). RESULTS: HCV RNA was detected in five of 26 (19.2%) livers with fulminant hepatic failure. All five HCV RNA-positive livers belonged to the group of non-toxic, non-autoimmune liver failure (n=20), three of them were found in the group of liver failure with unknown aetiology (n=12) and two in the group of HBV-associated liver failure (n=7), making an HCV incidence of 25%, 25% and 28.6%, in the different groups, respectively. HGV RNA was detected in 10 of 17 (58.8%) explants and in all four groups of fulminant hepatic failure as defined preoperatively. HBV DNA was identified in six livers of 26 patients (23.1%) with fulminant hepatic failure. Neither HCV RNA nor HBV DNA was detected in the livers of patients with toxic or autoimmune fulminant hepatic failure. CONCLUSIONS: These results indicate that HBV and HCV, but not HGV, play an aetiologic role in fulminant hepatic failure. HCV-positive cases were concentrated either in the group of otherwise unexplained fulminant hepatic failure or in the group of HBV fulminant hepatic failure. HGV-positive cases, on the other hand, were found within all four preoperatively defined groups, indicating a role as cofactor rather than as single aetiologic agent.     

Non-redundant data clustering

Data clustering is a popular approach for automatically finding classes, concepts, or groups of patterns. In practice, this discovery process should avoid redundancies with existing knowledge about class structures or groupings, and reveal novel, previously unknown aspects of the data. In order to deal with this problem, we present an extension of the information bottleneck framework, called coordinated conditional information bottleneck, which takes negative relevance information into account by maximizing a conditional mutual information score subject to constraints. Algorithmically, one can apply an alternating optimization scheme that can be used in conjunction with different types of numeric and non-numeric attributes. We discuss extensions of the technique to the tasks of semi-supervised classification and enumeration of successive non-redundant clusterings. We present experimental results for applications in text mining and computer vision.     

Crystallinity and lateral crystallite size of different UHMW PE materials

Nascent high-molecular-weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70–75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15–25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower-molecular-weight PE samples and for high-strength / modulus PE fibers of different origins.