Broadband microstrip antenna element and array

Foam-supported highly efficient microstrip antennas are described. Theoretical and experimental results show that bandwidths up to 15 percent can be obtained at the expense of an increase in the antenna height (to about 0.1 wavelength). The performance of an array of broadband elements fed by a microstrip corporate feed network is also described.     

Similarities between lime and limestone in wet—dry scrubbing

Lime is utilized as a sorbent in most commercial wet—dry scrubbing processes for SO₂ control, while limestone is not considered to be sufficiently reactive for such a purpose. Faced with the fact that limestone is potentially the least expensive sorbent for SO₂ control, a study was conducted to uncover ways to increase the reactivity of this sorbent in order to use it in wet—dry scrubbing applications. The study was focused on a comparison of the reactivity of lime and limestone during the dry reaction period. The conditions which have a major impact on the reactivity include the sorption capacity of water vapour, the BET surface area, the relative humidity and the sorbent utilization. The experiments revealed several similarities between the two sorbents, which led to a number of ways to obtain increased limestone acitivity.     

Microfluidic gradient-generating device for pharmacological profiling

We describe an on-chip microfluidic gradient-generating device that generates concentration gradients spanning nearly 5 orders of magnitude starting from a single concentration. The exiting stream of drugs held at different concentrations remains laminar in a recording chamber and can be presented as 24 discrete solutions to a cell-based sensor. The high-performance characteristics of the device are demonstrated by pharmacological screening of voltage-gated K+ channels (hERG) and ligand-gated GABA(A) receptors using scanning-probe patch-clamp measurements. Multiple data point dose-response curves and IC50 and EC50 values were rapidly obtained, typically in less than 30 min, through its combined functionality of gradient generation and open-volume laminar flow. The device facilitates rapid pharmacological profiling of ion channel and GPCR effectors and enables the acquisition of large numbers of data points with minute sample consumption and handling.     

Effect of postinduction nutrient feed composition and use of lactose as inducer during production of thermostable xylanase in Escherichia coli glucose-limited fed-batch cultivations

Escherichia coli is a microorganism routinely used in the production of heterologous proteins. The overexpression of a xylanase (Xyn 10 A Delta NC), which originated from the thermophile Rhodothermus marinus cloned under the control of the strong T7/lac promoter in a defined medium (mAT) using a substrate-limited feed strategy, was however shown to impose a significant metabolic burden on host cells. This resulted in a decreased cell growth rate and ultimately also a decreased target protein production. The investigation hence centers on the effect of some selected nutrient feed additives (amino acid [Cys] or TCA-intermediates [citrate, succinate, malate]) used to relieve the metabolic burden imposed during the feeding and postinduction phases of these glucose-limited fed-batch cultivations. The use of either succinic acid or malic acid as feed-additives resulted in an increase in production of approximately 40% of the heterologous thermostable xylanase. Furthermore, use of lactose as an alternative inducer of the T7/lac promoter was also proven to be a suitable strategy that significantly prolonged the heterologous protein production phase as compared with induction using isopropyl beta-D-thiogalactopyranoside (IPTG).     

Sphingolipid long chain bases

About 60 natural sphingolipid long chain bases have been identified or proposed. A review is given on their nomenclature, distribution, metabolism, biologic properties, chemistry and methods of characterization.     

Introducing a biosensor based technology for real-time biospecific interaction analysis

The peptido-leukotriene receptor(s) (PL) on the ferret isolated spleen strip have been characterised by functional studies using the naturally occurring leukotrienes (LTs), a range of structurally distinct PL antagonists, and by ligand binding studies. LTB4 (0.01-10 microM) was inactive on ferret spleen whereas LTC4, LTD4 and LTE4 produced concentration-related contractions with maximal responses, relative to noradrenaline, of 57% (EC50 0.28 microM), 60% (EC50 0.5 microM) and 7% respectively. The leukotriene responses were unaltered by L-serine borate, L-cysteine, indomethacin, phentolamine, propranolol, mepyramine, methysergide or atropine, suggesting that the peptido-leukotrienes were acting through distinct PL receptors. The PL1 antagonists, FPL 55712 (0.01-10 microM), ICI 198615 (10 microM), SK&F 104353 (10 microM) and MK541 (10 microM) were all inactive against LTC4- or LTD4-induced contractile responses. LTE4 was a partial agonist with respect to LTC4 and LTD4 with pKB values of 5.8 and 5.5 respectively. Nifedipine (0.1 microM) produced a rightward shift of the concentration-response curves to both LTC4 and LTD4 and depressed their maximal responses. An unacceptably high level of non-specific binding of [3H]LTD4 to membrane preparations of ferret spleen prevented characterisation of this receptor by ligand binding. These results suggest that the ferret spleen has a homogeneous population of a PL receptor type which is insensitive to existing PL1 receptor antagonists. The functional characteristics of this PL receptor type are similar to those of the PL2 receptor on other tissues. The absence of PL1 receptors on this tissue makes it particularly useful in identifying new and selective drug tools for the PL2 receptor.