The Danish SAR system: design and initial tests

In January 1986, the design of a high-resolution airborne C -band synthetic aperture radar (SAR) started at the Electromagnetics Institute of the Technical University of Denmark. The initial system test flights took place in November and December 1989. The authors describe the design of the system, its implementation, and its performance. They show how digital technology has been utilized to realize a very flexible radar with variable resolution, swath-width, and imaging geometry. The motion-compensation algorithms implemented to obtain the high resolution and the special features built into the system to ensure proper internal calibration are outlined. The data processing system, developed for image generation and quality assurance, is sketched, with special emphasis on the flexibility of the system     

Mechanistic studies of proteases and lipases for the detergent industry

The wash performance of three specific proteases (asp, lys/arg and glu specific, respectively) is demonstrated to be comparable to that of commercial unspecific detergent proteases (Alcalase® and Savinase®). A hypothesis for the high performance of these specific proteases is proposed. The influence of pH and ionic strength on protease performance is discussed. The removal of oily stains by lipases in detergent solution is improved only slightly under acidic conditions, whereas pH values >> pK_a of the fatty acids formed results in strongly enhanced removal. Wash trials with Lipolase^TM show very little effect of the lipase after the first wash, but high effect after the second and subsequent washes. This is explained by lipolytic activity under drying. Maximum activity is found when the water content of the cotton swatches is between 10 and 40% (w/w).     

A recombinant bacterial cell surface (S-layer)-major birch pollen allergen-fusion protein (rSbsC/Bet v1) maintains the ability to self-assemble into regularly structured monomolecular lattices and the functionality of the allergen

The mature crystalline bacterial cell surface (S-layer) proteinSbsC of Bacillus stearothermophilus ATCC 12980 comprises aminoacids 31–1099 and assembles into an oblique lattice type.As the deletion of up to 179 C-terminal amino acids did notinterfere with the self-assembly properties of SbsC, the sequenceencoding the major birch pollen allergen (Bet v1) was fusedto the sequence encoding the truncated form rSbsC_31–920.The S-layer fusion protein, termed rSbsC/Bet v1, maintainedthe ability to self-assemble into flat sheets and open-endedcylinders. The presence and the functionality of the fused Betv1 sequence was proved by blot experiments using BIP1, a monoclonalantibody against Bet v1 and Bet v1-specific IgE-containing serumsamples from birch pollen allergic patients. The location andaccessibility of the allergen moiety on the outer surface ofthe S-layer lattice were demonstrated by immunogold labelingof the rSbsC/Bet v1 monolayer, which was obtained by orientedrecrystallization of the S-layer fusion protein on native cellwall sacculi. Thereby, the specific interactions between theN-terminal part of SbsC and a distinct type of secondary cellwall polymer were exploited. This is the first S-layer fusionprotein described that had retained the specific propertiesof the S-layer protein moiety in addition to those of the fusedfunctional peptide sequence.     

Hydrolysis of triglycerides in the isolated perfused rat lung

The purpose of this study was to investigate the hydrolysis of saturated and unsaturated triglycerides by lung lipoprotein lipase and to measure the incorporation of triglyceride fatty acids into lung tissue lipids. Lipolytic activity was studied in the isolated ventilated rat lung, perfused for 100 min in a recycling system with Krebs Ringer bicarbonate containing bovine serum albumin, 5.6 mM glucose, and 1.5 or 10 mM triglyceride. Saturated triglycerides were hydrolyzed at significantly (p<0.05) lower rates than unsaturated triglycerides; tricaprylin, trimyristin and tripalmitin were hydrolyzed at 8.1+1.8, 5.4+1.5 and 9.5+1.8 μmol free fatty acids/g dry wt/100 min, respectively, whereas triolein and trilinolein were hydrolyzed at 20.2+1.8 and 20.6+0.3 μmol free fatty acids/g dry wt/100 min, respectively. The polyunsaturated triglycerides, trilinolein and triarachidonin were hydrolyzed at even higher rates (44.3+3.0 and 50.9+5.4 μmol free fatty acids/g dry wt/100 min, respectively). Intralipid infused at a concentration of 10 mM triglyceride was hydrolyzed at a significantly higher rate than at 1.5 mM triglyceride (58+6.3 μmol free fatty acids/g dry wt/100 min vs 16.6+1.7 μmol free fatty acids/g dry wt/100 min, respectively). Labeled unsaturated triglycerides were broken down at significantly higher rates than labeled saturated triglycerides. Incorporation of triglyceride-fatty acid into lung lipid was greater into neutral lipids than into phospholipids. The data suggest that (a) the factors that appear to affect lung lipoprotein lipase activity are composition and concentration of circulating triglyceride, (b) uptake of fatty acids into the tissue was proportional to the rate of hydrolysis of the emulsion, and (c) triglyceride-fatty acids could therefore be used by the lung for metabolic needs. The data presented in part at the Annual Meetings of the American Physiological Society, Atlanta, GA, April 1981, and the American Thoracic Society, Detroit, MI, May 1981, and published in abstract form-Fed. Proc. 40, 621 (1981), andAm. Rev. Respir. Dis. 123, 219 (1981).     

A solid state emf study of the pyrrhotite-magnetite equilibrium in the temperature interval 850 to 1275 K

The equilibrium 3/(1 −x)Fe_1−x S(s) + (5 − 2x)/(1 −x)O₂(g) Fe₃O₄(s) + 3/(1 −x)SO₂(g) was studied in the temperature interval 850 to 1275 K by measuring oxygen potentials in a galvanic cell containing calcia stabilized zirconia as solid electrolyte. The SO₂ activity was controlled by equilibrating the solid phases pyrrhotite and magnetite with a continuously flowing SO₂-Ar gas mixture of known composition. Formation of S₂ gas was taken into account and a recently published thermodynamic model for the pyrrhotite phase⁴ was used to derive the Gibbs energy change for the pyrrhotite-magnetite equilibrium and for the formation of Fe_1−x S as a function of the variables temperature and pyrrhotite composition.     

Mycotoxin Detection Plays “Cops and Robbers”: Cyclodextrin Chemosensors as Specialized Police?

As in a cops and robbers play we discover new mycotoxins and metabolites everyday and we are forced to develop new molecules quickly as chemo- or biosensors or to modify existing molecules able to recognize these new hazardous compounds. This will result in an enormous cost saving to agro-food industry through the prevention and reduction of product recalls and reduced treatment costs. Here we present a brief review of the rapid methods used to detect mycotoxins, considering usefulness and limits. Then we propose a new fast, efficient and cheap methodology, based on a combination of computer chemistry aided design and fluorescence, that can help to drive synthesis in a more efficient way.     

Formation of nanotubes and hollow nanoparticles based on Kirkendall and diffusion processes: a review

The Kirkendall effect is a consequence of the different diffusivities of atoms in a diffusion couple causing a supersaturation of lattice vacancies. This supersaturation may lead to a condensation of extra vacancies in the form of so-called "Kirkendall voids" close to the interface. On the macroscopic and micrometer scale these Kirkendall voids are generally considered as a nuisance because they deteriorate the properties of the interface. In contrast, in the nanoworld the Kirkendall effect has been positively used as a new fabrication route to designed hollow nano-objects. In this Review we summarize and discuss the demonstrated examples of hollow nanoparticles and nanotubes induced by the Kirkendall effect. Merits of this route are compared with other general methods for nanotube fabrication. Theories of the kinetics and thermodynamics are also reviewed and evaluated in terms of their relevance to experiments. Moreover, nanotube fabrication by solid-state reactions and non-Kirkendall type diffusion processes are covered.     

Changes in the Daphnia magna midgut upon ingestion of copper oxide nanoparticles: A transmission electron microscopy study

This work is a follow-up of our previous paper (Heinlaan et al., 2008. Chemosphere 71, 1308-1316) where we showed about 50-fold higher acute toxicity of CuO nanoparticles (NPs) compared to bulk CuO to water flea Daphnia magna. In the current work transmission electron microscopy (TEM) was used to determine potential time-dependent changes in D. magna midgut epithelium ultrastructure upon exposure to CuO NPs compared to bulk CuO at their 48 h EC₅₀ levels: 4.0 and 175 mg CuO/L, respectively. Special attention was on potential internalization of CuO NPs by midgut epithelial cells. Ingestion of both CuO formulations by daphnids was evident already after 10 min of exposure. In the midgut lumen CuO NPs were dispersed whereas bulk CuO was clumped. By the 48th hour of exposure to CuO NPs (but not to equitoxic concentrations of bulk CuO) the following ultrastructural changes in midgut epithelium of daphnids were observed: protrusion of epithelial cells into the midgut lumen, presence of CuO NPs in circular structures analogous to membrane vesicles from holocrine secretion in the midgut lumen. Implicit internalization of CuO NPs via D. magna midgut epithelial cells was not evident however CuO NPs were no longer contained within the peritrophic membrane but located between the midgut epithelium microvilli. Interestingly, upon exposure to CuO NPs bacterial colonization of the midgut occurred. Ultrastructural changes in the midgut of D. magna upon exposure to CuO NPs but not to bulk CuO refer to its nanosize-related adverse effects.Time-dependent solubilisation of CuO NPs and bulk CuO in the test medium was quantified by recombinant Cu-sensor bacteria: by the 48th hour of exposure to bulk CuO, the concentration of solubilised copper ions was 0.05 ± 0.01 mg Cu/L that was comparable to the acute EC₅₀ value of Cu-ions to D. magna (48 h CuSO₄ EC₅₀ = 0.07 ± 0.01 mg Cu/L). However, in case of CuO NPs, the solubilised Cu-ions 0.01 ± 0.001 mg Cu/L, explained only part of the toxicity.     

Development and validation of a novel real-time PCR method for the detection of celery (Apium graveolens) in food

The paper presents a novel real-time PCR method allowing the detection of traces of celery (Apium graveolens) in complex food matrices. The method is based on the amplification of a sequence of the gene coding for the Apium graveolens NADPH-dependent mannose-6-phosphate reductase. It allows the detection of three commonly used celery varieties, celery roots (Apium graveolens var. rapaceum), celery stalks (Apium graveolens var. dulce) and leaf celery (Apium graveolens var. secalinum) and does not show any cross-reactivity with 64 biological species, including ten members of the Apiaceae family. The limit of detection, determined by analysing serially diluted celery extracts, is 10 pg celery DNA for all three celery varieties. In spiked model sausages, the LOD is 0.005% celery. The real-time PCR method was applied to 26 commercial food products. Celery DNA was found in one out of ten samples without any information about the presence of celery.