Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1572-879X
    Keywords: microwave absorption ; electrical conductivity ; single crystal particles ; doped Si powders ; ZnO powder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A microwave absorption technique based on cavity perturbation theory is shown to be applicable for electrical conductivity measurements of both a small, single-crystal particle and finely divided powder samples whenσ values fall in either the low (σ〈0.1 Ω−1 cm−1) or the intermediate (0.1 ≤σ≤ 100 Ω−1 cm−1) conductivity region. The results here pertain to semiconductors in the latter region. If the skin depth of the material becomes significantly smaller than the sample dimension parallel to theE-field, an appreciable error can be introduced into the calculated conductivity values; however, this discrepancy is eliminated by correcting for the field attenuation associated with the penetration depth of the microwaves. A modification of this approach utilizing the skin depth allows a first-order correction to be applied to powder samples which results in the accurate measurement of absoluteσ values, and results with doped Si powders are compared toσ values obtained from one small single particle using this microwave technique as well as reported DCσ values determined with single crystals. The use of this microwave absorption technique with small particles having high surface/volume ratios, such as catalyst supports and oxide catalysts, under controlled environments can provide fundamental information about adsorption and catalytic processes on such semiconductor surfaces. An application to a ZnO powder demonstrates this capability.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0983
    Keywords: Conidiation ; Fungi ; brlA ; Microbial development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Conidiation in the filamentous ascomycete Aspergillus nidulans requires activation of brlA, a well-characterized transcriptional regulator of genes that are induced specifically during asexual development. We have isolated and characterized developmental mutations in six loci, designated fluG, flbA, flbB, flbC, flbD, and flbE, that result in defective development and reduced brlA expression. These mutants grow indeterminately to produce masses of aerial hyphae resulting in the formation of cotton-like colonies with a “fluffy” morphology. The results of growth and epistasis tests involving all pairwise combinations of fluffy mutations indicate complex hierarchical relationships among these loci. We discuss these genetic interactions and propose that there are multiple mechanisms for activating brlA.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...