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Free Radicals: Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.
 JoVE Bioengineering

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

1Department of Chemistry and Biochemistry, University of Denver, 2Magnetic Imaging Group, Applied Physics Division, Physical Measurements Laboratory, National Institute of Standards and Technology, 3Department of Radiology, Geisel School of Medicine, Dartmouth University, 4Department of Biochemistry, West Virginia University, 5Department of Electrical and Computer Engineering, University of Denver, 6Department of Engineering, University of Denver

JoVE 54068

 JoVE Bioengineering

Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process

1Laboratory for Protection and Physiology, Empa, Swiss Federal Laboratories for Materials Science and Technology, 2Laboratory of Advanced Fibers, Empa, Swiss Federal Laboratories for Materials Science and Technology, 3Division of Neonatology, University Hospital Zurich

JoVE 51680

 Science Education: Essentials of Environmental Science

Measuring Tropospheric Ozone

JoVE Science Education

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University

Ozone is a form of elemental oxygen (O3), a molecule of three oxygen atoms bonded in a structure that is highly reactive as an oxidizing agent. Ozone occurs in both the stratosphere and the troposphere levels of the atmosphere. When in the stratosphere (located approximately 10-50 km from the earth’s surface), ozone molecules form to the ozone layer and help prevent harmful UV rays from reaching Earth’s surface. In lower altitudes of the troposphere (surface - approximately 17 km), ozone is harmful to human health and is considered an air pollutant contributing to photochemical smog (Figure 1). Ozone molecules can cause damage directly by harming respiratory tissue when inhaled or indirectly by harming plant tissues (Figure 2) and softer materials including tires on automobiles. Outdoor tropospheric ozone is formed at ground level when nitrogen oxides (NOx) and volatile organic compounds (VOCs) from automobile emissions are exposed to sunlight. Consequently, health concerns over ozone concentrations escalate in sunny conditions or when and where automobile use is increased. Reaction: NO2 + VOC + sunlight &

 Science Education: Essentials of Organic Chemistry

Schlenk Lines Transfer of Solvents

JoVE Science Education

Source: Laboratory of Dr. Ian Tonks — University of Minnesota Twin Cities

Schlenk lines and high vacuum lines are both used to exclude moisture and oxygen from reactions by running reactions under a slight overpressure of inert gas (usually N2 or Ar) or under vacuum. Vacuum transfer has been developed as a method separate solvents (other volatile reagents) from drying agents (or other nonvolatile agents) and dispense them to reaction or storage vessels while maintaining an air-free environment. Similar to thermal distillations, vacuum transfer separates solvents by vaporizing and condensing them in another receiving vessel; however, vacuum transfers utilize the low pressure in the manifolds of Schlenk and high vacuum lines to lower boiling points to room temperature or below, allowing for cryogenic distillations. This technique can provide a safer alternative to thermal distillation for the collection of air- and moisture-free solvents. After the vacuum transfer, the water content of the collected solvent can be tested quantitatively by Karl Fischer titration, qualitatively by titration with a Na/Ph2CO solution, or by 1H NMR spectroscopy.

 JoVE Chemistry

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

1Department of Materials Science and Engineering, University of Washington, 2Molecular Engineering and Sciences Institute, University of Washington, 3Clean Energy Institute, University of Washington, 4Institut für Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 5Department of Chemical Engineering, University of Washington, 6Department of Chemistry, University of Washington

JoVE 54047

 JoVE Medicine

Flexible Colonoscopy in Mice to Evaluate the Severity of Colitis and Colorectal Tumors Using a Validated Endoscopic Scoring System

1Division of Gastroenterology, Case Western Reserve University School of Medicine, Cleveland, 2Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, 3Digestive Health Research Center, Case Western Reserve University School of Medicine, Cleveland

JoVE 50843

 JoVE Biology

En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries

1Cardiovascular and Aging Research, Department of Medicine, Division of Physiology, Faculty of Science, University of Fribourg, 2Kidney Control of Homeostasis, Swiss National Centre of Competence in Research, 3System Physiology, Department of Medicine, Division of Physiology, Faculty of Science, University of Fribourg

JoVE 53718

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