Now showing items 14083-14102 of 14993

    • Toxic and mutagenic potentials of herbal teas

      Park, Douglas L.; Manteiga, Raquel, 1963- (The University of Arizona., 1991)
      Three commercially available herbal tea preparations (Weightless, Female Toner, and PMS) and one single ingredient herbal preparation, Chaparral (Larrea tridentata), were sequentially extracted with solvents of decreasing polarity (water, methanol and chloroform) and the crude extracts obtained screened for toxic/mutagenic potentials using the brine shrimp (Artemia sp.), mouse acute toxicity, Salmonella/microsomal mutagenicity, and chicken embryo bioassays. The crude aqueous extract from Weightless Tea was very toxic to brine shrimp larvae and had a cathartic action in mice at the highest concentration tested. While Weightless tea crude water extract was not mutagenic to Salmonella typhimurium TA100 at the concentrations tested, three chromatographic isolates obtained from a silica Gel 60 column were mutagenic to the test organism. Two of these isolates were detoxified after inclusion of a microsomal activation system. The teratogenic potentials of these isolates are unknown as the results obtained from the chicken embryo bioassay were not conclusive.
    • Toxic effects of jojoba meal fed to weanling mice

      Cook, Esther Marie, 1952- (The University of Arizona., 1977)
    • Toxic Masculinity on Television: A Content Analysis of Preferred Adolescent Programs

      Stevens-Aubrey, Jennifer; Roberts, Lindsay; LaPierre, Matthew; Harwood, Jake (The University of Arizona., 2019)
      The present study examined the prevalence of toxic masculinity on adolescent television programs using social cognitive theory (Bandura, 2001) and social cognitive theory of gender development and differentiation (Bussey & Bandura, 1999) as a theoretical lens. Drawing from a sample of current television shows that adolescents watch, the content analysis observes two indicators of toxic masculinity: aggression (physical aggression and expressions of anger) and an avoidance of femininity (a mockery of femininity, a suppression of vulnerable emotions and an intolerance of homosexuality). The results indicated that toxic masculinity occurs within 36.8% (n = 869) of scenes on adolescent television shows. Furthermore, gender differences occurred in the enactment of specific indicators of toxic masculinity. Physical aggression was exhibited more often by male characters than female characters, but female characters enacted a suppression of vulnerable emotions more often than male characters. Future research along with theoretical and practical implications in regard to toxic masculinity are discussed.
    • Toxicity of Arsenic, Uranium, PFOA, and PFOS to Chlorella Sorokiniana and Potential for Bioremeditation Applications

      Ogden, Kimberly; Leo, Caitlyn; Guzman, Roberto; Hickenbottom, Kerri (The University of Arizona., 2020)
      Off-grid, mobile nanofiltration units are being explored as a method for point-source arsenic and uranium removal from drinking water on Navajo Nation. One proposed treatment method for the concentrated brine treatment method produced during this process is the use of microalgae to remove contaminants via biosorption. Chlorella Sorokiniana was chosen for this study because of its high tolerance for salt and heat as well as previously demonstrated biosorption abilities. This study seeks to establish that C. sorokiniana is a viable species to produce water fit for agricultural use nanofiltration brine by removing of arsenic, uranium, and two species of PFAS. Initial toxicity screenings, growth inhibition experiments, and an analysis of extracellular contaminant concentrations for arsenic, uranium, PFOA, and PFOS were performed to establish a proof of concept. Initial toxicity tests showed arsenic concentrations between 400-500 mg/L caused cell death in 72 hours for C. sorokiniana. From two-week growth inhibition experiments, the species IC50 for arsenic was found to be 184 mg As/L. While growth rate decreased by over 50% at the highest test concentration (200 mg As/L), biomass productivity only decreased by 26%. ICP-MS analysis of the growth media found at higher concentrations C. sorokiniana removed around 10% of arsenic in solution and accumulated 15 mg As/g biomass. When exposed to uranium, C. sorokiniana exhibited cell death after 72 hours at 20 mg/L and an IC50 of 7.04 mg/L. At 10 mg/L there was a 48% decrease in biomass productivity. The highest uranium removal achieved was 87% at an initial concentration of 0.5 mg/L. The adsorption capacity of C. sorokiniana was found to vary between 0.25 mg and 0.40 mg U/ g biomass. Neither arsenic or uranium caused cell death or significant decrease in cell growth at the highest concentrations found in environmental sampling: 0.055 mg As/L and 0.75 mg U/L. However, C. sorokiniana was not able to remove enough of either contaminant to achieve levels below the MCLs. PFOA caused cell death after 72 hours at 3.22 g/L but did not significantly impact C. sorokiniana growth rate or biomass productivity at concentrations up to 100 mg/L. For initial PFOA concentrations of 0.558, 5.58, and 55.8 mg/L, a 74.6%, 71.8%, and a 71.2% reduction in extracellular PFOA was observed. Estimated accumulation per gram biomass ranged from 0.2 – 22 mg PFOA/g biomass and increased with initial PFOA concentration. PFOS did not cause cell death at any tested concentrations, including its solubility limit. Furthermore, it did not impact growth rate or biomass productivity. For initial PFOS concentrations of 0.0485, 0.485, and 4.85 mg/L, a 90.6%, 97.4%, and a 96.6% reduction in extracellular PFOS was observed. Estimated accumulation per gram biomass ranged from 0.02 – 2.7 mg PFOS/g biomass and increased with initial PFOA concentration. The results indicate that there is potential for C. sorokiniana to be used in bioremediation of both PFOS and PFOA.
    • TOXICITY OF DI-2-ETHYLHEXYL PHTHALATE IN THE DIET OF PENAEID SHRIMP.

      Hobson, James Farrier. (The University of Arizona., 1982)
    • The toxicity of simmondsin, a glycoside found in jojoba, (Simmondsia chinensis)

      Williams, Rodney Ray (The University of Arizona., 1980)
    • Toxicity of synthetic pyrethroid insecticides to the honey bee (Apis mellifera L.)

      Waller, Gordon D.; Taylor, Kevin Stuart, 1958- (The University of Arizona., 1987)
      Honey bees (Apis mellifera L.) were exposed to six pyrethroid insecticides using four application techniques. Toxicities of the insecticides were compared. Results of topical and contact tests placed the six pyrethroids in one of three categories based on their relative toxicity to honey bees; highly toxic (cyfluthrin, cypermethrin, and permethrin), moderately toxic (flucythrinate and fenvalerate), and non-toxic (fluvalinate). The residue tests, by contrast, simulated field conditions by using sprayed cotton leaves for exposure. This test showed that both compound and formulation played an important role in determining toxicity. The conditioning test combined some of the previously used techniques and refined them into a test for detecting behavioral changes to bees following sublethal exposure to pesticides. Insecticide-treated honey bees had a lower learning curve than their respective control group. This indicates that, although bees may survive poisoning from pesticides, certain physiological functions are affected.
    • Toxicological damage to the pulmonary endothelium

      Flowers, Mary Helen (The University of Arizona., 1981)
    • A toxicological study of the medicinal plant Cacalia decomposita

      Burton, Lloyd Edward, 1922- (The University of Arizona., 1956)
    • The toxicology of sulfur oxides and the in vitro responses of lung macrophages

      Crooks, Debra Louise (The University of Arizona., 1978)
    • Toynbee's view of the relation between society and the individual

      Peterson, Luther James, 1925- (The University of Arizona., 1955)
    • Trace Element Composition of Apatite from Intrusive Rocks in Northeastern Nevada, USA

      Barton, Mark D.; Dabbs, Jennifer Marie; Mazdab, Frank K.; Steele-MacInnis, Matthew (The University of Arizona., 2016)
      The apatite crystal structure-A5(TO4)3X-allows for complex substitutions of various minor and trace elements including volatile constituents, rare earth elements, and redox sensitive elements (e.g., As, Mn, Fe, S) (Piccoli and Candela, 1994; Piccoli and Candela, 2002; Pan and Fleet, 2002; Teiber et al., 2015; Harlov, 2015). In this study, apatite grains from 19 intrusions across northeastern Nevada with varied petrogenetic and metallogenic properties were analyzed by electron probe microanalysis (EPMA) to obtain major and trace element abundances. Systematic variations in Sr and REE concentrations in apatite grains from granitic host rocks are the result of competition with pre-existing and coexisting minerals in silicate melts. The presence of zoning in cathodoluminescence colors combined with high Sr concentrations in apatite from many of the Eocene granodiorite rocks suggest magma mixing affected the geochemical evolution in many of the Eocene igneous systems. In addition, high Sr concentrations in apatite grains from Late Cretaceous two-mica granites may reflect significant magmatic input from lower crustal and/or mantle sources despite the felsic nature of these intrusive rocks.A new EPMA analytical routine to measure arsenic down to detection limits of approximately 20 ppm allowed a more extensive characterization of As concentration in igneous apatite than has previously been published. Still, correlations between As and other trace-element concentrations are not evident, which may reflect the simple substitution of As5+ for P5+ in the apatite structure. Petrologic controls on As content include redox state, indicated by the high Asapat/Asbulk-rock in relatively oxidized intrusive rocks. An additional control is competition among other magmatic phases, exsolving aqueous fluids, or sulfide melts, indicated by enrichment of As in apatite cores relative to apatite rims. Past studies on redox-sensitive elements in igneous apatite have focused on Mn and S, but with further investigation, As may also prove to be a key redox-sensitive trace element in apatite for interpreting igneous and hydrothermal processes.
    • The trace element content of plants growing in saline and alkaline media

      Aba-Husayn, Mansur Mohammed, 1942- (The University of Arizona., 1970)