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  • calcium transport  (3)
  • Solvatochromism  (2)
  • Acoustics; Man/System Technology and Life Support  (1)
  • 1
    ISSN: 1573-6881
    Keywords: Mitochondrial calcium ; inorganic phosphate ; membrane permeability transition ; calcium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The role of inorganic phosphate as inhibitor of mitochondrial membrane permeability transition was studied. It is shown that in mitochondria containing a high phosphate concentration, i.e., 68 nmol/mg, Ca2+ did not activate the pore opening. Conversely, at lower levels of matrix phosphate, i.e., 38 nmol/mg, Ca2+ was able to induce subsequent pore opening. The inhibitory effect of phosphate was apparent in sucrose-based media, but it was not achieved in KCl media. The matrix free Ca2+ concentration and matrix pH were lowered by phosphate, but they were always higher in K+-media. In the absence of ADP, phosphate strengthened the inhibitory effect of cyclosporin A on carboxyatractyloside-induced Ca2+ efflux. Acetate was unable to replace phosphate in the induction of the aforementioned effects. It is concluded that phosphate preserves selective membrane permeability by diminishing the matrix free Ca2+ concentration.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6881
    Keywords: Matrix calcium ; BAT mitochondria ; membrane permeability transition ; adenine nucleotide translocase ; calcium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The role of the adenine nucleotide translocase on Ca2+ homeostasis in mitochondria from brown adipose tissue was examined. It was found that in mitochondria incubated with 50 μM Ca2+, ADP was not needed to retain the cation, but it was required for strengthening the inhibitory effect of cyclosporin on membrane permeability transition as induced by menadione. In addition, carboxyatractyloside was unable to promote matrix Ca2+ release, even though it inhibits the ADP exchange reaction. However, when the Ca2+ concentration was increased to 150 μM, carboxyatractyloside did induce Ca2+ release, and ADP favored Ca2+ retention. Determination of cardiolipin content in the inner membrane vesicles showed a greater concentration in brown adipose tissue mitochondria than that found in kidney mitochondria. It is suggested that the failure of the adenine nucleotide translocase to influence membrane permeability transition depends on the lipid composition of the inner membrane.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6881
    Keywords: Matrix calcium ; BAT mitochondria ; membrane permeability transition ; adenine nucleotide translocase ; calcium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The role of the adenine nucleotide translocase on Ca2+ homeostasis in mitochondria from brown adipose tissue was examined. It was found that in mitochondria incubated with 50 μM Ca2+, ADP was not needed to retain the cation, but it was required for strengthening the inhibitory effect of cyclosporin on membrane permeability transition as induced by menadione. In addition, carboxyatractyloside was unable to promote matrix Ca2+ release, even though it inhibits the ADP exchange reaction. However, when the Ca2+ concentration was increased to 150 μM, carboxyatractyloside did induce Ca2+ release, and ADP favored Ca2+ retention. Determination of cardiolipin content in the inner membrane vesicles showed a greater concentration in brown adipose tissue mitochondria than that found in kidney mitochondria. It is suggested that the failure of the adenine nucleotide translocase to influence membrane permeability transition depends on the lipid composition of the inner membrane.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0947-3440
    Keywords: Polarity scale ; Solvatochromism ; Solvent polarity scale ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: More than 100 solvents and the gas phase were used to develop a solvent dipolarity-polarizability scale that combines the medium dipolarity and polarizability into a single parameter (SPP) calculated from the UV-visible spectra of 2-(dimethyl-amino)-7-nitrofluorene (DMANF) and its homomorph 2-fluoro-7-nitrofuorene (FNF). The proposed scale compares favourably for nonprotic solvents with existing solvent polarity scales including Kosower's Z, Dimroth and Reichardt's ET(30), Brooker's χR, Dong and Winnick's Py; Kamlet, Abboud, and Taft's π*, and Drago's S′ scale. When data are derived from electronic transitions, they provide an accurate description for the solvent effect in UV-Vis, IR, NMR, and fluorescence spectroscopy as well as in other chemical areas including thermodynamics and kinetics.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0947-3440
    Keywords: Solvent basicity scale ; Solvent effects ; Solvatochromism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A total of 202 organic solvents and the gas phase were placed on a solvent basicity scale for hydrogen bond acceptor based on parameter SB. The value of such a parameter can readily be determined from the UV/Vis spectrum for an appropriate acid probe (5-nitroindoline) (NI) and its non-acid homomorph (1-methyl-5-nitroindoline) (MNI). The proposed scale can advantageously substitute the more widely used solvent scales such as Gutmann's donor number (DN), the Koppel-Palm B(MeOD) scale, and the Taft-Kamlet β scale. While data for the proposed scale are derived only from electronic transitions, they are accurately descriptive of solvent basicity in both spectroscopy (UV/Vis, IR and NMR) and miscellaneous chemical areas (thermodynamic, kinetics, and electrochemistry).
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2019-07-13
    Description: The International Space Station (ISS) provides a unique environment where crewmembers from the US and our international partners work and live for as long as 6 to 12 consecutive months. During these long-durations ISS missions, noise exposures from onboard equipment are posing concerns for human factors and crewmember health risks, such as possible reductions in hearing sensitivity, disruptions of crew sleep, interference with speech intelligibility and voice communications, interference with crew task performance, and reduced alarm audibility. It is crucial to control acoustical noise aboard ISS to acceptable noise exposure levels during the work-time period, and to also provide a restful sleep environment during the sleep-time period. Acoustic dosimeter measurements, obtained when the crewmember wears the dosimeter for 24-hour periods, are conducted onboard ISS every 60 days and compared to ISS flight rules. NASA personnel then assess the acoustic environment to which the crewmembers are exposed, and provide recommendations for hearing protection device usage. The purpose of this paper is to provide an update on the status of ISS noise exposure monitoring and hearing conservation strategies, as well as to summarize assessments of acoustic dosimeter data collected since the Increment 36 mission (April 2013). A description of the updated noise level constraints flight rule, as well as the Noise Exposure Estimation Tool and the Noise Hazard Inventory implementation for predicting crew noise exposures and recommending to ISS crewmembers when hearing protection devices are required, will be described.
    Keywords: Acoustics; Man/System Technology and Life Support
    Type: ICES-2015-239 , JSC-CN-33631 , International Conference on Environmental Systems; Jul 12, 2015 - Jul 16, 2015; Bellevue, WA; United States
    Format: application/pdf
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