A novel current limitation principle basedon application of liquid metals

In this paper, a new current limiting principle based on the application of liquid metals is proposed. This principle takes advantage of the arcless commutation of currents to a gradually increasing parallel resistance and makes it possible to realize a current-controlled resistor for very high currents, which can be used to limit the fault currents in power networks. The conditions for the arcless current commutation are investigated theoretically and the optimum profile for the parallel resistor is derived. An experimental setup is constructed to investigate the behavior of the separating contacts under different current amplitudes, different current steepnesses, and different resistance profiles. The experimental results relating to the commutation phase are compared to the theoretical limits.     

Novel nanofibre filter medium attracts waterborne pathogens

Through a colaborative project an innovative filter medium has been developed that not only efficiently removes bacteria from water, but is capable of achieving >6 log removal of viruses through electrokinetic adsorption. Fred Tepper, Argonide Corp, Tanya Rivkin, National Renewable Energy Laboratory & George Lukasic, Biological Consulting Services present the medium's test data.     

Cholesterol vehicle in experimental atherosclerosis. 23. Effects of specific synthetic triglycerides

Earlier work has shown that increasing concentration of palmitic acid at the sn-2 position of a fat enhances the atherogenic properties of that fat. This effect has been observed with lard, tallow, cottonseed oil, and palm oil. In the experiment reported here, we have studied the atherogenic effects of four synthetic fats fed to rabbits as 58% (w/w) of the total fat (15%) (w/w) of a semipurified diet containing 0.05% cholesterol. The fats being tested were: 1,3-stearoyl-2-oleoylglycerol (SOS); 1,2-stearoyl-3-oleoylglycerol (SSO); 1,3-palmitoyl-2-oleoylglycerol (POP); and 1,2-palmitoyl-3-oleoylglycerol (PPO). After 20 wk on diet there were no differences among the groups in weight gain, liver weight, serum, or liver lipids. These data are consistent with our previous findings. There were significant differences in atherosclerosis. The most severe atherosclerosis was observed in group PPO and the least in groups SSO and POP. Severity of atherosclerosis was graded visually on a 0–4 scale. The average atherosclerosis [(aortic arch and thoracic aorta)÷2] was: SOS-1.35; SSO-0.97; POP-0.83; and PPO-1.80. Fecal fat excretion (an indicator of fat absorption) was higher in the two groups fed the stearic acid-rich fats and lower in groups fed the palmitic acid-rich fats. There were no differences in low density lipoprotein particle size. The results confirm previous findings concerning the increased atherogenicity of fats bearing palmitic acid at the sn-2 position. The mechanism underlying these observations is moot but may, in part, reflect greater absorption of the atherogenic fat.     

Influence of vitamin C on hydroxylation and side chain oxidation of cholesterol in vitro

The addition of ascorbic acid (20–160 μg) to mitochondrial preparations of rat or guinea pig liver has no effect upon the oxidation of [26-¹⁴C]-cholesterol to¹⁴CO₂. The 7α-hydroxylation of cholesterol by rat liver microsomes is also unaffected by addition of ascorbic acid. Hydroxylation by guinea pig liver microsomes is increased in the presence of ascorbic acid, but the results are not statistically significant.     

Linoleic acid amides: Effect on cholesteremia and atherosclerosis

Several of a series of linoleic acid amides have been reported to inhibit cholesterol-induced atherosclerosis in rabbits. The three amides which have been studied to the greatest extent are (in order of increasing activity) N-cyclohexyl linoleamide (AC23), N(α methylbenzyl) linoleamide (AC223), and N[α-phenyl-β-(p-tolyl) ethyl] linoleamide (AC485). We have found AC223 to inhibit cholesterol absorption in rats and to slightly inhibit exogenous but not endogenous cholesteremia in rabbits. In a fiber-free diet, AC223 reduces serum cholesterol and liver triglyceride levels. Rats were also fed a basal semipurified diet with and without AC223. Fecal excretion of labeled exogenous (as [¹⁴C] cholesterol) or endogenous (as [¹⁴C] mevalonolactone) steroid was 44 and 43% higher in drug treated groups. The mechanism of hypocholesteremic action of the linoleamides appears to involve inhibition of cholesterol absorption.     

Automatic identification of bacterial types using statistical imaging methods

The objective of the current study is to develop an automatic tool to identify microbiological data types using computer-vision and statistical modeling techniques. Bacteriophage (phage) typing methods are used to identify and extract representative profiles of bacterial types out of species such as the Staphylococcus aureus. Current systems rely on the subjective reading of profiles by a human expert. This process is time-consuming and prone to errors, especially as technology is enabling the increase in the number of phages used for typing. The statistical methodology presented in this work, provides for an automated, objective and robust analysis of visual data, along with the ability to cope with increasing data volumes.     

Terahertz lenses made by compression molding of micropowders

We present a simple and versatile approach for fabricating terahertz lenses based on compression molding of micropowder polymer materials in a tabletop hydraulic press. To demonstrate the feasibility of this approach, a biconvex lens shape is calculated using a ray-tracing algorithm and lenses based on two different micropowders are fabricated. As the powder materials have different refractive indices, the resulting lenses share the same geometric shape but differ in their respective focal length. The focusing properties of the lenses are evaluated by transversal and sagittal beam profile measurements in a fiber-coupled terahertz time-domain spectroscopy system, confirming the excellent imaging qualities of the compression molded lenses.     

Wetting behavior of polymer coated nanoporous anodic alumina films: transition from super-hydrophilicity to super-hydrophobicity

We show that nanoporous anodic alumina films, with pore diameters in the range 10-80 nm, can be transformed from being very hydrophilic (or super-hydrophilic) to very hydrophobic (or super-hydrophobic) by coating the surface with a thin (2-3 nm) layer of a hydrophobic polymer. This dramatic transformation happens as a result of the interplay between surface morphology and surface chemistry. The coated surfaces exhibit 'sticky' hydrophobicity as a result of ingress of water into the pores by capillary action. The wetting parameters (contact angle and contact angle hysteresis) exhibit qualitatively different dependences on pore diameters in coated and uncoated films, which are explained by invoking appropriate models for wetting.