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Gear trains are plagued by self-excited vibrations that are concentrated at the mesh frequency and its harmonics due to their varying mesh stiffness and deviations from the ideal involute profile. This is even more pronounced in spur gears due to their lower contact ratio in comparison to helical gears. For an electric vehicle, due to the absence of an internal combustion engine, noise and vibration signature of the gearbox becomes an important aspect of the vehicle's comfort. However, the presence of a traction motor offers the advantage of having a potential actuator for actively countering these vibrations without adding any additional weight or packaging constraints. This paper presents a fundamental insight into the effect of introducing controlled torque ripples at the mesh frequency and its harmonics, on the noise and vibration characteristics, and the efficiency of the gear mesh. The study utilises a dynamic model of a single stage gear train that accounts for the time varying mesh stiffness and sliding friction at the gear teeth contact. This model is used to provide an understanding of gear mesh dynamics and their resulting interaction with the imposed torque ripples. The study demonstrates the positive effects that controlled torque ripples can have on the noise and vibration behaviour of gear trains and the underlying mechanics that govern this improvement.

Highlights a study in which a two-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. What the impeller periphery and the volute contour are replaced by in the model; Thorough description of the model; Why the model is an improvement over the quasi-steady flow model of Colding-Jorgensen (1980).

[H]205-501, a noncatechol dopaminergic agonist, is presented as a ligand with high affinity (K ∼ 1 nM) and high selectivity for dopamine receptors. pK values of dopaminergic agonists derived from competition isotherms in the [H]205-501 binding assay correlate very well with their potency in the acetylcholine release assay, which is controlled by dopamine D receptors. There is however no correlation with their potency stimulating adenylate cyclase, a process controlled by dopamine D receptors. Thus [H]205-501 is the first agonist ligand selective for dopamine D receptors. [ABSTRACT FROM AUTHOR]

Background: Taxol, a promising agent for the treatment of cancer, has entered phase II clinical trials. Nevertheless, it belongs to the class of compounds that show impaired retention in multidrug-resistant cells expressing P-glycoprotein (Pgp), a drug efflux pump. Chemosensitizers like verapamil modulate multidrug resistance by interfering with the efflux action of Pgp and thus can decrease drug resistance or can restore drug sensitivity by restoring normal drug accumulation and distribution within the multidrug-resistant tumor cell. The two strongest, nearly equipotent chemosensitizers identified to date are the cyclosporine derivative SDZ PSC 833 and the semisynthetic cyclopeptolide SDZ 280-446.Purpose: This study was designed to investigate the capacities of verapamil, SDZ PSC 833, and SDZ 280-446 to decrease resistance of two multidrug-resistant cell lines to taxol.Methods: We studied in vitro the growth of two multidrug-resistant tumor cell lines displaying high resistance to taxol: multidrug-resistant Chinese hamster ovary cells and murine monocytic leukemia P388 cells. We determined the taxol concentration that produced 50% inhibition of cell growth (IC50) in the two multidrug-resistant cell lines and in the parent cell lines, in the presence of a range of chemosensitizer concentrations (0-30 microM). IC50 values were determined in the presence and in the absence of verapamil, SDZ PSC 833, or SDZ 280-446.Results: At nontoxic concentrations (0.3-1 microM), SDZ PSC 833 and SDZ 280-446 produced an almost complete reversal of the high taxol resistance of the multidrug-resistant tumor cells, whereas only partial restoration of sensitivity to taxol was achieved with verapamil.Conclusion: SDZ PSC 833 and SDZ 280-446 can restore the normal taxol sensitivity of highly resistant multidrug-resistant tumor cells.Implications: The combination of taxol with SDZ PSC 833 or SDZ 280-446 may be recommended for treatment of multidrug-resistant cancers. [ABSTRACT FROM AUTHOR]

The quantitative determination of dehydrogenase activity in mitochondria, using 2,3,5-triphenyltetrazolium chloride as H-acceptor, is described. The results obtained with this technique are compared with those given by the methods of Warburg and Thunberg. [ABSTRACT FROM AUTHOR]