A new recoil distance technique using low energy coulomb excitation in inverse kinematics

We report on the first experiment combining the Recoil Distance Doppler Shift technique and multistep Coulomb excitation in inverse kinematics at beam energies of 3-10 A MeV. The setup involves a standard plunger device equipped with a degrader foil instead of the normally used stopper foil. An array of particle detectors is positioned at forward angles to detect target-like recoil nuclei which are used as a trigger to discriminate against excitations in the degrader foil. The method has been successfully applied to measure lifetimes in ¹²⁸Xe and is suited to be a useful tool for experiments with radioactive ion beams.     

Interaction of dietary fatty acids and cyclosporine a in the borderline hypertensive rat: Tissue fatty acids

In this study we examined (i) the effects of cyclosporine A (CS) on tissue lipid composition and (ii) the effect of changes in dietary n−6 fatty acids on tissue responses to CS. Fatty acid composition of liver, kidney, heart and brain were determined after 4 wk of treatment with CS (10 mg/kg·d p.o.) in male borderline hypertensive rats (BHR, n=4/group), whose diet was supplemented with either safflower oil or evening primrose oil (EPO). Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine/phosphatidylinositol, triglyceride and cholesteryl ester fatty acids were measured in kidney, heart, brain and liver. The same parameters were also measured in safflower-fed BHR (n=4) receiving placebo. The effects of CS on liver microsomal Δ9, Δ6 and Δ5 desaturasesin vitro were also followed. CS affected the fatty acid composition of all tissues examined, with the greatest changes seen in the renal phosphatidylcholine and phosphatidylserine/phosphatidylinositol fractions. All CS-induced changes that occurred in the liver, brain and renal fatty acids were reversed by EPO. CS elevated Δ9 desaturase but had no effect on Δ6 and Δ5 desaturase. In light of (i) the observation that EPO normalizes renal function and blood pressure in CS-treated BHR, and (ii) the importance of the kidney in blood pressure regulation, the data suggest that the beneficial effects of EPO on CS toxicity may involve changes in renal phospholipid fatty acid profiles.     

Two heteromeric kinesin complexes in chemosensory neurons and sensory cilia of Caenorhabditis elegans

Chemosensation in the nervous system of the nematode Caenorhabditis elegans depends on sensory cilia, whose assembly and maintenance requires the transport of components such as axonemal proteins and signal transduction machinery to their site of incorporation into ciliary structures. Members of the heteromeric kinesin family of microtubule motors are prime candidates for playing key roles in these transport events. Here we describe the molecular characterization and partial purification of two heteromeric kinesin complexes from C. elegans, heterotrimeric CeKinesin-II and dimeric CeOsm-3. Transgenic worms expressing green fluorescent protein driven by endogenous heteromeric kinesin promoters reveal that both CeKinesin-II and CeOsm-3 are expressed in amphid, inner labial, and phasmid chemosensory neurons. Additionally, immunolocalization experiments on fixed worms show an intense concentration of CeKinesin-II and CeOsm-3 polypeptides in the ciliated endings of these chemosensory neurons and a punctate localization pattern in the corresponding cell bodies and dendrites. These results, together with the phenotypes of known mutants in the pathway of sensory ciliary assembly, suggest that CeKinesin-II and CeOsm-3 drive the transport of ciliary components required for sequential steps in the assembly of chemosensory cilia.     

Heat-transfer phenomena in water-cooled zinc-fuming furnace jackets

In the zinc slag-fuming process, zinc is removed from lead blast furnace slag by reduction with a coal-air mixture injected into the slag through submerged tuyeres. The furnace is constructed of water-cooled jackets which freeze a slag layer and contain the bath. This greatly reduces vessel wear caused by the violently agitated and corrosive bath. The jackets, however, fail due to the formation of cracks which grow from the slag face through the working face of the jacket to the water channel. In this study, in-plant measurements and mathematical modeling of heat transfer in the jackets have been combined to elucidate the mechanism of failure. The working face of a water jacket was instrumented with thermocouples and installed in a fuming furnace at the Trail smelter of Cominco Ltd., Trail, BC. Measurements revealed the presence of large thermal transients or temperature “spikes” in the panel in the region immediately above the tuyeres. These were generally observed during charging and tapping of the furnace and are likely associated with disturbances on the surface of the bath or gas injection effects when the liquid level is low. Temperatures at the midthickness were seen to rise by as much as 180 °C above the steady-state level. Under these conditions, low-cycle fatigue may lead to crack formation and propagation. A mathematical modeling analysis of the transient freezing phenomena indicates that the temperature spikes are associated with sudden slag falloff and direct contact of molten slag on the jacket. In order to reduce slag falloff, an increased number of anchoring fins should be used in critical areas.