Stripping medium requirement in continuous countercurrent deodorization

A mathematical formula was derived that allows the stripping steam requirement of the countercurrent deodorization process to be calculated as a function of system pressure, vapor pressure of the pure volatile compound, initial and final volatiles contents, and the number of transfer units (an equipment parameter) of the countercurrent deodorizer. Just as in batch or cross-flow deodorization systems, the steam requirement in countercurrent systems is proportional to the system pressure and inversely proportional to the vapor pressure of the pure volatile compound. Increasing the number of transfer units (for instance, by increasing column height) to more than two makes the countercurrent system require less steam than cross-flow systems with a vaporization efficiency of 0.6. In addition, the short residence time in a countercurrent deodorization column minimizes side reactions and allows the deodorization temperature to be raised without generating unwanted by-products such as trans-isomers and/or oligomers of unsaturated fatty acids. The increased deodorization temperature increases the vapor pressure of the pure volatiles and leads to further savings in stripping medium and motive steam. Countercurrent deodorization systems therefore require less energy than cross-flow deodorization systems and/or produce oil with fewer unwanted by-products.     

Simple Water Level Controller for Irrigation and Drainage Canals

A simple water level controller for irrigation and drainage canals is proposed; the proposed controller has a master-slave structure where the slaves control the flow rates through the control structures. The master controller consists of PI-based controllers for feedback, and a decoupler and feedforward controller that are based on the inversion of a simple dynamic model of the canal system. The applicability of the controller is demonstrated in field experiments.     

Characteristics of the luminal proton pump in malpighian tubules of the ant

The active pump mechanisms involved in K+ secretion of the malpighian tubules of the ant and present in the luminal membrane were investigated on isolated, luminally perfused tubules of Formica. The specific blocker for vacuolar type ATPases, bafilomycin A1, was found to half-maximally inhibit secretion at a concentration of 10(-5) mol/l when added to the lumen. N-Ethylmaleimide reduced the calculated short circuit current (Isc) to 78 and 21% of control value when added at 5 x 10(-4) mol/l, respectively, to the lumen and the bath. Reducing luminal pH inhibited Isc with a half-maximal inhibition at a luminal pH of 4.5. Acidified omeprazole, Schering compound 28080 and vanadate (both 10(-3) and 10(-4) mol/l) inhibited Isc only partially. The present data suggest that the luminal membrane of ant malpighian tubules contains a H+ pump. This pump is only poorly bafilomycin-sensitive. Furthermore, additional active transport systems responsible for secretion may be present. Part of these results have been published as abstracts.     

Signal-regulatory protein is selectively expressed by myeloid and neuronal cells

Signal-regulatory proteins (SIRP) are transmembrane glycoproteins with three extracellular Ig-like domains, closely related to Ag receptors Ig, TCR, and MHC, and a cytoplasmic domain with two immunoreceptor with tyrosine-based inhibition motifs that can interact with src homology 2 domain-containing phosphatases. SIRP have previously been shown to inhibit signaling through receptor tyrosine kinases, but their physiologic function is unknown. Here we demonstrate by expression cloning that the mAbs ED9, ED17, and MRC-OX41 recognize rat SIRP. In addition, we show for the first time that rat SIRP is selectively expressed by myeloid cells (macrophages, monocytes, granulocytes, dendritic cells) and neurons. Moreover, SIRP ligation induces nitric oxide production by macrophages. This implicates SIRP as a putative recognition/signaling receptor in both immune and nervous systems.     

Protein stabilization by hydrophobic interactions at the surface

The contribution of the solvent-exposed residue 63 to thermal stability of the thermolysin-like neutral protease of Bacillus stearothermophilus was studied by analyzing the effect of twelve different amino acid substitutions at this position. The thermal stability of the enzyme was increased considerably by introducing Arg, Lys or bulky hydrophobic amino acids. In general, the effects of the mutations showed that hydrophobic contacts in this surface-located region of the protein are a major determinant of thermal stability. This observation contrasts with general concepts concerning the contribution of surface-located residues and surface hydrophobicity to protein stability and indicates new ways for protein stabilization by site-directed mutagenesis.     

Dry fractionation

With the increase in palm oil production, the dry fractionation process has also gained in importance, both in comparison with other fractionation processes and in terms of the number of tonnes per annum. This has been assisted by the development of far less labour‐intensive processes and improved understanding of the physical chemistry involved. This new insight indicates that temperature uniformity in a crystalliser is not necessary, which opens the door to continuous crystallisation. Combining this continuous crystallisation with a proven continuous separation system such as the conical sieve centrifuge could well lead to a fully continuous dry fractionation process. It is not there yet but likely to arrive.     

The use of ultra- and nanofiltration techniques in homogeneous catalyst recycling

In recent years, the application of membrane technology in homogeneous catalyst recycling has received widespread attention. This technology offers a solution for the major drawback of homogeneous catalysis, that is, recycling of the catalyst. From both an environmental and an industrial point of view, this technology is very interesting, since it allows the future application of homogeneous catalysts in the synthesis of commercial products, leading to faster, cleaner and highly selective green industrial processes. In this account, an overview is given of the promising results obtained in the field of homogeneous catalyst recycling using nanofiltration membrane technology.