The Hertz Corporation

About: The Hertz Corporation is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 9562 authors who have published 11044 publications receiving 447929 citations. The organization is also known as: Hertz Rental Car & Hertz Rent-a-Car.

Stress softening in natural rubber vulcanizates. Part II. Stress softening effects in pure gum and filler loaded rubbers

Abstract: Considerable stress softening occurs in both gum and filler-loaded vulcanizates and when compared at the same stress the extent of softening is similar in both gum and filled vulcanizates. It thus appears that the softening process is mainly due to the rubber phase alone. Apparent differences between the stress—strain hysteresis loops of gum and filler-loaded vulcanizates are traced to an increase in the effective strain in the rubber phase resulting from the presence of black. This is discussed in Part I of this series. The mechanism of stress softening in gum vulcanizates is not well understood. Possible sources include (1) breaking and remaking of crosslinks during extension, (2) residual local orientation of network chains persisting after recovery, and (3) breaking of network chains.

Ecology of Mycorrhizae and Mycorrhizal Fungi

Abstract: It is normal for the roots of most plant species, including Angiosperms, Gymnosperms, Pteridophytes, and some Thallophytes, to form mutualistic associations with different groups of soil fungi. Charged to investigate the culture of truffles in the Kingdom of Prussia, Frank (1885) instead discovered and described such mutualistic associations in temperate forest trees and named them mycorrhiza (fungus root). He believed that the fungi performed the function of root hairs, which were lacking in these much modified dual structures.

Microbial biomass measurements in forest soils: Determination of kC values and tests of hypotheses to explain the failure of the chloroform fumigation-incubation method in acid soils

Abstract: The chloroform fumigation-incubation method underestimates the amount of microbial biomass C in strongly acid soils (pH In the fumigation-incubation method, the fumigated soil is inoculated with a few mg of non-fumigated soil after the fumigant is removed but before incubation begins, to increase the size of the microbial recolonizing population. In soils above about pH 5, it makes little difference whether or not the soil is inoculated. However, in some of our strongly acid soils this was not so and a large inoculum increased the quantity of CO2 produced after fumigation. Neither the use of an inappropriate kC factor nor inadequate inoculation appear, in themselves, to be sufficient to explain why the fumigation-incubation method underestimates the amount of microbial biomass in strongly acid soils. We suggest the main reason is that the recolonizing population in strongly acid soils is unable to metabolize non-microbial organic matter as fast as the native population in non-fumigated soil, so that the use of a non-fumigated soil as control will lead to low values for biomass.

Identification and characterization of mutations in housefly (Musca domestica) acetylcholinesterase involved in insecticide resistance

Abstract: Acetylcholinesterase (AChE) insensitive to organophosphate and carbamate insecticides has been identified as a major resistance mechanism in numerous arthropod species. However, the associated genetic changes have been reported in the AChE genes from only three insect species; their role in conferring insecticide insensitivity has been confirmed, using functional expression, only for those in Drosophila melanogaster . The housefly, Musca domestica , was one of the first insects shown to have this mechanism; here we report the occurrence of five mutations (Val-180 → Leu, Gly-262 → Ala, Gly-262 → Val, Phe-327 → Tyr and Gly-365 → Ala) in the AChE gene of this species that, either singly or in combination, confer different spectra of insecticide resistance. The baculovirus expression of wild-type and mutated housefly AChE proteins has confirmed that the mutations each confer relatively modest levels of insecticide insensitivity except the novel Gly-262 → Val mutation, which results in much stronger resistance (up to 100-fold) to certain compounds. In all cases the effects of mutation combinations are additive. The mutations introduce amino acid substitutions that are larger than the corresponding wild-type residues and are located within the active site of the enzyme, close to the catalytic triad. The likely influence of these substitutions on the accessibility of the different types of inhibitor and the orientation of key catalytic residues are discussed in the light of the three-dimensional structures of the AChE protein from Torpedo californica and D. melanogaster .