Vom albatros zur „idealen windmühle”: Zum vorsprung dänischer aerodynamik um die jahrhundertwende

The science of aerodynamics was in a desolate state around the turn of the century. Phenomena like resistance or updrift in a flow were known and studied, but not understood properly. The theoretical understanding was still dominated by the Newtonian resistance theory, which had already proved insufficient since the 18th century. The Danish scientists Hans Christian Vogt, Johan Irminger and Poul la Cour provided significant contributions to aerodynamics around the turn of the century and belonged to the first to break with the traditional understanding. Vogt studied a large variety of natural aerodynamic phenomena like the flight of birds or the movement of fishes. He recognized that updrift and resistance are interrelated phenomena and explained updrift by a reduced air pressure on the upper side of a wing, fin or blade. His friend Johan Irminger provided careful measurements of the air pressure around a body in an air flow, which confirmed Vogts ideas. Poul la Cour made even more precise measurements in a wind tunnel and provided the best experimental understanding of aerodynamic phenomena hitherto available. Based on his investigations he concluded the design features of an „ideal windmill”-which proved to be exactly those of the traditional windmill.     

Effect of Process Conditions on the Physical and Sensory Properties of Extruded Oat-Corn Puff

ABSTRACT: The effect of processing variables, including screw speed (200,300, and 400 rpm), moisture content (18, 19.5, and 21%), and four different percentages (55,70,85, and 100%) of oat flour, on the extrudate physical properties (expansion, bulk density, and texture profiles) and sensory properties were studied. Increasing the percentage of oat flour resulted in extrudates with a lower specific length, higher bulk density, lower lightness, higher redness, lower yellowness, higher hardness, and lower springiness, gumminess, and chewiness. Higher moisture content reduced expansion, except for the 100% oat flour puffs. Screw speed had no significant effect on the bulk density, specific length, and expansion ratio. Principal Component Analysis showed that decreasing moisture content and increasing screw speed resulted in increased product temperature, which was highly correlated with attributes of a more expanded product such as lightness, crispness, shininess, and an open cell structure. With a higher screw speed and a higher product temperature, corn-related flavors were more likely to develop. High correlations between physical and sensory properties were observed.     

Single Cell Bioprinting with Ultrashort Laser Pulses

Tissue engineering requires the precise positioning of mammalian cells and biomaterials on substrate surfaces or in preprocessed scaffolds. Although the development of 2D and 3D bioprinting technologies has made substantial progress in recent years, precise, cell-friendly, easy to use, and fast technologies for selecting and positioning mammalian cells with single cell precision are still in need. A new laser-based bioprinting approach is therefore presented, which allows the selection of individual cells from complex cell mixtures based on morphology or fluorescence and their transfer onto a 2D target substrate or a preprocessed 3D scaffold with single cell precision and high cell viability (93–99% cell survival, depending on cell type and substrate). In addition to precise cell positioning, this approach can also be used for the generation of 3D structures by transferring and depositing multiple hydrogel droplets. By further automating and combining this approach with other 3D printing technologies, such as two-photon stereolithography, it has a high potential of becoming a fast and versatile technology for the 2D and 3D bioprinting of mammalian cells with single cell resolution.     

Photolytic hydrogenation of the polyynes C6H2, C8H2, C10H2, and C12H2 in n-hexane with 253.6 nm radiation

The polyynes C₆H₂, C₈H₂, C₁₀H₂, and C₁₂H₂ in n-hexane exposed to 253.6 nm radiation “disappear” much faster in air-free solutions than in solutions in equilibrium with air. These observations suggest that the disappearance is due to reaction of the polyyne molecules in the ground state with a photolytically produced chemical species which in solutions in equilibrium with air is overwhelmingly scavenged by dissolved O₂. Although no hydrogenation products were firmly established the most likely chemical is atomic hydrogen.     

Solubility of Fullerenes C60 and C70 in Seven Normal Alcohols and Their Deduced Solubility in Water

The solubilities of C₆₀ and C₇₀ at 25°C in seven normal alcohols obey the relationship InY = a + bX + cX², where Y is solubility and X is the Hildebrand solubility parameter of the solvent. Extrapolation to the solubility parameter of water yields solubilities in water of 1.3'10^-11 (C₆₀) and 1.3'10^-10(C₇₀) ng/ml with an uncertainty of one order of magnitude.     

Temporal Release of Flavor Compounds from Low-fat and High-fat Ice Cream During Eating

ABSTRACT: Fat controls the intensity and the release rate of volatile compounds because of its solvent property. Our objective was to understand the effect of fat on the flavor release behavior exhibited while ice cream is eaten. The temporal flavor profiles of ice creams, which contained various fat levels and were spiked with known amounts of selected volatiles, were determined by a temporal modified purge and trap and time-intensity analyses. Stale and cherry flavors were released faster and at higher intensities as fat content decreased. Fat had the opposite effect on vanilla flavor release. Temporal modified purge and trap analysis was an effective method to observe the release of some flavor compounds.     

Di- and oligosaccharide substrate specificities and subsite binding energies of pig intestinal glucoamylase-maltase

BACKGROUND: Wake-up tests may be necessary during scoliosis surgery to ensure that spinal function remains intact. METHODS: Intra- and postoperative wake-up tests were performed together with somatosensory cortical evoked potentials (SCEPs) monitoring in 40 patients randomized to either midazolam (M) or propofol (P) infusions for scoliosis surgery. Other anaesthetic medication was similar in both groups. At the surgeon's request, N2O was turned off and midazolam or propofol infusions were discontinued. In the M group, flumazenil was given in refracted doses. Patients were asked to move hands and feet. The test was repeated immediately after the end of surgery. RESULTS: The median intraoperative wake-up times were 2.9 min in the M group and 16.0 min in the P group. The respective postoperative wake-up times were 1.8 and 13.9 min. The quality of both intra- and postoperative arousals was significantly better in the M group. Twelve patients in the P group could not be awakened intraoperatively within 15 min and were given naloxone. One of these patients woke up violently and dislodged the endotracheal tube. Another patient in the P group had explicit recall of the test, but no pain. Five patients in the M group became resedated in the recovery room. Cost of anaesthetic drugs was similar in both groups. Satisfactory intraoperative SCEPs were recorded from 17 patients in each group. There were no neurological sequelae. CONCLUSIONS: Wake-up tests can be conducted faster and better with midazolam-flumazenil sequence compared with propofol.     

Barmag:用于生产特种纱线的新型空气变形机

介绍了由Barmag公司研制的CATY新型空气变形机,可用于生产市场前景广泛的特种纱线。     

Remarks on the adaptive control of linear plants with unknown high-frequency gain

Adaptive control of first-order linear systems of the form $\text{x}\text{?}\text{= ax + bu}$ with the sign of b unknown is considered. It is shown that stabilizing adaptive controllers exist that have globally bounded gain and prespecified terminal dynamics.     

Imaging streptavidin 2D crystals on biotinylated lipid monolayers at high resolution with the atomic force microscope

Streptavidin crystals were grown on biotinylated lipid monolayers at an air/water interface and transferred onto highly oriented pyrolytic graphite (HOPG). These arrays could be imaged to a resolution below 1 nm using the atomic force microscope. The surface topographs obtained were compared with negative-stain electron microscopy images and the atomic model as determined by X-ray crystallography. The streptavidin tetramer (60 kDa) exposes two free biotin-binding sites to the buffer solution, while two are occupied by linkage to the lipid monolayer. Therefore, the streptavidin 2D crystals can be used as nanoscale matrices for binding biotinylated compounds. Furthermore, this HOPG-based preparation method provides a general novel approach to study the structure of protein arrays assembled on lipid monolayers with the AFM.