32 research outputs found
Point Of Zero Charge Determination in Soils and Minerals via Traditional Methods and Detection of Electroacoustic Mobility
Points of zero charge were determined on two highly weathered surface soils from Puerto Rico, an Oxisol and Ultisol, as well as mineral-standard kaolinite and synthetic goethite using three methods: (1) potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in solutions of varying ionic strength (I) (point of zero salt effect), (2) direct assessment of surface charges via non-specific ion adsorption as a function of pH and I (point of zero net charge), and (3) electroacoustic mobility of reversible particles as it varies with pH and I (isoelectric point). The first two methods yielded points of zero charge for kaolinite (2.7–3.2) and synthetic goethite (7.4–8.2) comparable to those reported previously, indicating the reliability of these analyses. The soil values ranged from 3.9 to 4.4 for the Oxisol and 2.3 to 3.7 for the Ultisol. Electroacoustic mobility, as measured by the AcoustoSizer™, is a parameter that has yet to be thoroughly tested for mineral or soil systems as a viable alternative to PZC assessment. The points of zero charge from electroacoustic mobility of kaolinite (3.8–4.1) and synthetic goethite (8.1–8.2) were similar to values obtained by electrophoretic mobility. Furthermore, the values found for the Oxisol (3.4–3.5) and Ultisol (2.6–2.7) were in the range expected for these soils
The Pursuit of Democracy: the Racial Subject and Sympathy’s Limits in \u3ci\u3eLeaves of Grass\u3c/i\u3e
Walt Whitman\u27s Leaves of Grass has long been celebrated as a great work of American democracy, a work of democratic poetics. Throughout the text, Whitman goes to great lengths to sympathize with as many different sects of American society as possible. But where do his sympathies deserve scrutiny? By analyzing Whitman\u27s relationship to the black, enslaved subject throughout the text, it becomes clear that there are limits to sympathy, and sympathetic intentions can inadvertently inflict violence upon subjugated groups. In turn, it becomes evident that Whitman’s democratic project is much more flawed and complicated than the way it is often presented in popular culture
The phenomenon of phototoxicity and long-term risks of commonly prescribed and structurally diverse drugs
Photosensitivity to structurally diverse drugs is a common but under-reported adverse cutaneous reaction and can be classified as phototoxic or photoallergic. Phototoxic reactions occur when the skin is exposed to sunlight after administering topical or systemic medications that exhibit photosensitizing activity. These reactions depend on the dose of medication, degree of exposure to ultraviolet light, type of ultraviolet light, and sufficient skin distribution volume. Accurate prediction of the incidence and phototoxic response severity is challenging due to a paucity of literature, suggesting that phototoxicity may be more frequent than reported. This paper reports an extensive literature review on phototoxic drugs; the review employed pre-determined search criteria that included meta-analyses, systematic reviews, literature reviews, and case reports freely available in full text. Additional reports were identified from reference sections that contributed to the understanding of phototoxicity. The following drugs and/or drug classes are discussed: amiodarone, voriconazole, chlorpromazine, doxycycline, fluoroquinolones, hydrochlorothiazide, nonsteroidal anti-inflammatory drugs, and vemurafenib. In reviewing phototoxic skin reactions, this review highlights drug molecular structures, their reactive pathways, and, as there is a growing association between photosensitizing drugs and the increasing incidence of skin cancer, the consequential long-term implications of photocarcinogenesis