Lead effect

When collisions occur between gas phase atoms or molecules there is an exchange of energy, which leads effectively to a broadening of energy levels. If t is the mean time between collisions and each collision results in a transition between two states there is a line broadening Av of the transition, where... 

Dose (blood lead)-effect data are available in the study by Fowler et al. (1980). Rats exposed to lead acetate in the drinking water through the dams during gestation and lactation and then directly until 9 months of age had the following external exposures (ppm lead), internal exposures ( pg lead/dL in blood), and renal effects 0 ppm (controls), 5 pg/dL, no lesions 0.5 ppm, 4.5 pg/dL, no lesions 5 ppm,... 

ALAD, an enzyme occurring early in the heme pathway, is also considered a sensitive indicator of lead effect (Hemberg et al. 1970 Morris et al. 1988 Somashekaraiah et al. 1990 Tola et al. 1973). Because there is no well-defined blood lead threshold at which inhibition of ALAD does not occur, it allows measurement of the effect on the general population at environmental lead levels and does not require high exposure levels as with occupational workers (Hemberg et al. 1970). However, ALAD activity may also be decreased with other diseases or conditions such as porphyria, liver cirrhosis, and alcoholism (Somashekaraiah et al. 1990). 

Baghurst PA, Robertson EF, McMichael AJ, et al. 1987. The Port Pirie cohort study Lead effects on pregnancy outcome and early childhood development. Neurotoxicology 8 395-401. 

Emhart CB. 1988. Cofactors in research on the environmental toxicology of childhood Issues and examples from lead effects studies. In Environmental toxicology of childhood. University of Nebraska, Children and the Law Series. 

Johansson L, Wide M. 1986. Long-term exposure of the male mouse to lead Effects on fertility. 

Lilienthal H, Winneke G. 1996. Lead effects on the brain stem auditory evoked potentials in monkeys during and after the treatment phase. Neurotoxicol Teratol 18 17-32. 

Mantere P, Haenninen H, Hemberg S. 1982. Subclinical neurotoxic lead effects Two-year follow-up studies with psychological test methods. Neurobehav Toxicol Teratol 4 725-727. 

Marcus AH, Schwartz J. 1987. Dose-response curves for erythrocyte protoporphyrin vs blood lead Effects of iron status. Environ Res 44 221-227. 

Moore MR, Goldberg A, Yeung-Laiwah AAC. 1987. Lead effects on the heme biosynthetic pathway Relationship to toxicity. Ann NY Acad Sci 514 191-203. 

Sakai T, Morita Y. 1996. Delta-aminolevulinic acid in plasma or whole blood as a sensitive indicator of lead effects, and its relation to the other heme-related parameters. Int Arch Occup Environ Health 68(2) 126-132. 

Winneke G, Beginn U, Ewert T, et al. 1984. [Understanding of subclinical lead effects on the nervous system of children with known prenatal exposure in Nordenhami], Schriftenr Ver Wasser Boden Lufthyg 59 215-230. (German)... 

Zajac CS, Abel EL. 1990. Lack of lead effects on fetal development and offspring learning when combined with alcohol in the Long-Evans rat. Teratology 41 33-41. 

Data for lead effects on mammalian wildlife are scarce. Shore (1995) indicates that lead residues in soils could successfully predict lead concentrations in kidneys and livers of wood mice and field voles however, this could not be demonstrated for shrews. In view of the large interspecies differences in lead responses reported for domestic livestock and laboratory populations of small animals (Table 4.9), more research is needed to determine if lead criteria for these groups are applicable to sensitive species of mammalian wildlife. 

Barrett, J. and PJ. Livesey. 1985. Low level lead effects on activity under varying stress conditions in the developing rat. Pharmacol. Biochem. Behav. 22 107-118. 

From this starting point, London employed standard techniques of Rayleigh-Schrodinger perturbation theory to evaluate the leading effects of the intermolecular... 

Mudzinski, S.P. et al., Analysis of lead effects on in vivo antibody-mediated immunity in several mouse strains, Toxicol. Appl. Pharmacol., 83, 321, 1986. 

Kerkvliet, N.I. and Baecher-Steppan, L., Immunotoxicology studies on lead Effects of exposure on tumor growth and cell-mediated immunity after syngeneic or allogeneic stimulation, Immunopharmacology 4, 213, 1982. 

Recently a very detailed study on the single chain dynamic structure factor of short chain PIB (M =3870) melts was undertaken with the aim to identify the leading effects limiting the applicability of the Rouse model toward short length scales [217]. This study was later followed by experiments on PDMS (M =6460), a polymer that has very low rotational barriers [219]. Finally, in order to access directly the intrachain relaxation mechanism experiments comparing PDMS and PIB in solution were also carried out [186]. The structural parameters for both chains were virtually identical, Rg=19.2 (21.3 A). Also their characteristic ratios C =6.73 (6.19) are very similar, i.e. the polymers have nearly equal contour length L and identical persistence lengths, thus their conformation are the same. The rotational barriers on the other hand are 3-3.5 kcal/mol for PIB and about 0.1 kcal/mol for PDMS. We first describe in some detail the study on the PIB melt compared with the PDMS melt and then discuss the results. 

Nano-scale and molecular-scale systems are naturally described by discrete-level models, for example eigenstates of quantum dots, molecular orbitals, or atomic orbitals. But the leads are very large (infinite) and have a continuous energy spectrum. To include the lead effects systematically, it is reasonable to start from the discrete-level representation for the whole system. It can be made by the tight-binding (TB) model, which was proposed to describe quantum systems in which the localized electronic states play an essential role, it is widely used as an alternative to the plane wave description of electrons in solids, and also as a method to calculate the electronic structure of molecules in quantum chemistry. 

Lead effect Medium Low3 Low3 Low3 Very lowb High Low3... 

In the case of normal hydrogen [14] the difference is mainly determined by a relativistic contribution of order (Za)2Ep (so-called Breit term [15]). In muonic atoms the leading effect is due to vacuum polarization and it is of order aEp. 

Reaction Pathway and Products. In the presence of a catalytic amount of a tetraphenylporphyrin (TPP) Mn(III) complex (34) and sodium borohydride, treatment of cyclohexene with excess oxygen (air) in benzene-ethanol leads effectively to cyclohexanol and cy-clohexenol. The reaction is quite different from the known autoxidation catalyzed by TPP Mn(III) in the absence of NaBH4 (Figure 7). The most significant characteristics of the present TPPMn-NaBH4-02 reaction compared with the autoxidation are ... 

The leading effect of the full d shells should come from the coupling with the empty states nearest in energy, the valence s states of the noble metal. Such... 

It is certain that we do not know what the leading effect in determining droplet stability and droplet distribution in miniemulsion is at this point both colloidal and ripening effects probably play a role. Future work is therefore needed to clarify these problems. 

---