Magnetic properties of iron alloys

The purpose of this work was to compare the properties of high purity atomized iron powder compacts with conventional high purity irons and to show the effects of porosity on magnetic properties. It was found that if powders were hot repressed so that no porosity was present, the magnetic properties were as good as or better than conventional high purity irons, depending on the sintering conditions employed. Intrinsic properties were similar because the amount of iron available to magnetize was equivalent. Structure-sensitive properties depended on the grain size. If the compacts were sintered above the delta transition temperature, these properties were equivalent to the purest of the conventional high purity irons. As the compacts became less dense and more porosity was present, induction and remanent magnetization decreased linearly with density; resistivity increased. In the case of structure-sensitive properties, porosity restricted grain growth. Small, closely spaced pores caused the greatest degradation of properties. Equations were derived through regression analyses and were found to explain more than 90% of the data. The intrinsic properties: induction, remanent magnetization, and resistivity were all linear functions of the density. The maximum permeability and the coercive force were power functions of the mean grain size intercept. These equations provide a basis for design of magnetic components using P/M compacts. If the properties that are desired are known, the density or the grain size required may be calculated. From this, the powder and the processing conditions required can be established to provide the desired properties.     

Synthesis and characterization of near monodisperse oligomeric polystyrenes

Oligomeric (<10³) polystyrenes have been synthesized on a practical scale by the use of secbutyllithium and triethylamine in cyclohexane. These samples were found to possess relatively narrow molecular weight distributions. The product analysis was accomplished by viscosity, vapour pressure osmometry, gel permeation chromatography and gas chromatography.     

Mechanics of penetration and perforation

The various deformation mechanisms that occur when a projectile strikes a target at normal incidence are analyzed with the aid of a computer simulation program. An objective of the analysis is to identify the important material parameters in targets and projectiles that influence perforation.     

Inhibition by adenosine triphosphate of heart microsomal neutral lipase activity

Triacylglycerol lipolysis was inhibited by palmitate, in the isolated perfused normal rat heart. Acetate or acetylcarnitine could reproduce the inhibitory effects of palmitate. Since heart neutral lipase plays an important role in the lipolysis of heart triacylglycerols, the effects of acetylcarnitine, acetyl CoA and related metabolites on the microsomal neutral lipase activity were studied. ATP inhibited the enzyme activity in a concentration-dependent manner without a lag phase. AMP and adenylyl imidodiphosphate, two compounds structurally related to ATP but whose phosphate groups cannot be transferred, did not inhibit the microsomal lipase activity. These results suggested that ATP inhibited the lipase activity through the transfer of its phosphate group. It is proposed that cellular ATP concentration is a determinant of tricylglycerol lipolysis in the heart.     

NMR-based metabolomics: a powerful approach for characterizing the effects of environmental stressors on organism health

It is important to assess the chronic effects of chemical, physical, and biological stressors on organisms in the environment. Appropriate methods must enable rapid, inexpensive, and multibiomarker analyses of organism health. Here we investigate withering syndrome in red abalone (Haliotis rufescens), an important wild and farmed shellfish species along the Pacific coast, using a metabolomic approach that combines the metabolic profiling capabilities of nuclear magnetic resonance spectroscopy (NMR) with pattern recognition methods. Foot muscle, digestive gland, and hemolymph samples were collected from healthy, stunted, and diseased abalone, and the extracts were analyzed by NMR. Following spectral preprocessing, principal components analyses of the metabolite profiles were conducted. Our results confirm that NMR-based metabolomics can successfully distinguish the biochemical profiles of the three groups of animals, in every type of tissue or biofluid studied. Furthermore, this discovery-based approach successfully identified novel metabolic biomarker profiles associated with withering syndrome. The application of these methods for investigating other environmental stressors is discussed, as are the advantages of NMR-based metabolomics for biomonitoring, particularly in conjunction with gene and protein expression profiling.     

Terpenoids as major precursors of dissolved organic matter in landfill leachates,surface water,and groundwater

13C NMR analyses of hydrophobic dissolved organic matter (DOM) fractions isolated from a landfill leachate contaminated groundwater near Norman, OK; the Colorado River aqueduct near Los Angeles, CA; Anaheim Lake, an infiltration basin for the Santa Ana River in Orange County, CA; and groundwater from the Tomago Sand Beds, near Sydney, Australia, found branched methyl groups and quaternary aliphatic carbon structures that are indicative of terpenoid hydrocarbon precursors. Significant amounts of lignin precursors, commonly postulated to be the major source of DOM, were found only in trace quantities by thermochemolysis/gas chromatography/mass spectrometry of the Norman Landfill and Tomago Sand Bed hydrophobic DOM fractions. Electrospray/tandem mass spectrometry of the Tomago Sand Bed hydrophobic acid DOM found an ion series differing by 14 daltons, which is indicative of aliphatic and aryl-aliphatic polycarboxylic acids. The product obtained from ozonation of the resin acid, abietic acid, gave a similar ion series. Terpenoid precursors of DOM are postulated to be derived from resin acid paper sizing agents in the Norman Landfill, algal and bacterial terpenoids in the Colorado River and Anaheim Lake, and terrestrial plant terpenoids in the Tomago Sand Beds.     

Dietary CLA decreased weight loss and extended survival following the onset of kidney failure in NZB/W F1 mice

In an earlier study, we showed that feeding CLA immediately after weaning prolonged survival of NZB/W F1 mice after onset of proteinuria. In the present study, the feeding of CLA was delayed until mice had developed proteinuria. Thirty NZB/W F1 mice were fed a regular rodent chow after weaning. Urine samples were collected to detect proteinuria. Once a mouse was proteinuria positive, it was then randomly assigned to a 0.5% CLA supplement semipurified diet or a control diet (supplement 0.5% corn oil). The next proteinuria positive mouse was then assigned to the opposite diet to which the first mouse was assigned. Mice fed the control diet lost 25% more body weight (13.0 g) than mice fed the CLA diet (9.7 g). Moreover, CLA-fed mice survived an average 1.7-fold longer (148 d) than mice fed the control diet (89 d) after the onset of proteinuria. This follow-up study confirmed that dietary CLA had a beneficial effect in the autoimmune NZB/W F1 mouse. In summary, the cachectic symptom of systemic lupus erythematosus was decreased by dietary CLA and survival days were increased over control group.