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Depression, Chemical: The decrease in a measurable parameter of a Physiological process, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or Metabolic process, including enzymatic and other pharmacological processes, by a drug or other chemical.
 Science Education: Essentials of General Chemistry

Freezing-Point Depression to Determine an Unknown Compound

JoVE Science Education

Source: Laboratory of Lynne O' Connell — Boston College

When a solid compound is dissolved in a solvent, the freezing point of the resulting solution is lower than that of the pure solvent. This phenomenon is known as freezing-point depression, and the change in temperature is directly related to the molecular weight of the solute. This experiment is designed to find the identity of an unknown compound by using the phenomenon of freezing-point depression to determine its molecular weight. The compound will be dissolved in cyclohexane, and the freezing point of this solution, as well as that of pure cyclohexane, will be measured. The difference between these two temperatures allows for the calculation of the molecular weight of the unknown substance.

 Science Education: Essentials of Organic Chemistry

Conducting Reactions Below Room Temperature

JoVE Science Education

Source: Laboratory of Dr. Dana Lashley - College of William and Mary

Demonstration by: Matt Smith

When new bonds are formed in the course of a chemical reaction, it requires that the involved species (atoms or molecules) come in very close proximity and collide into one another. The collisions between these species are more frequent and effective the higher the speed at which these molecules are moving. A widely used rule of thumb, which has its roots in the Arrhenius equation1, states that raising the temperature by 10 K will approximately double the rate of a reaction, and raising the temperature by 20 K will quadruple the rate: (1) Equation (1) is often found in its logarithmic form: (2) where k is the rate of the chemical reaction, A is the frequency factor (relating to frequency of molecular collisions), Ea is the activation energy required for the reaction, R is the ideal gas constant, and T is the temperature at which the r

 JoVE Neuroscience

The Use of Magnetic Resonance Spectroscopy as a Tool for the Measurement of Bi-hemispheric Transcranial Electric Stimulation Effects on Primary Motor Cortex Metabolism

1Department of Psychology, University of Montréal, 2Montreal Neurological Institute, McGill University, 3Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota

JoVE 51631

 JoVE Neuroscience

A Method for Systematic Electrochemical and Electrophysiological Evaluation of Neural Recording Electrodes

1School of Psychological Science, La Trobe University, 2Intelligent Polymer Research Institute, University of Wollongong, 3ARC Centre of Excellence for Electromaterials Science, 4Health Innovations Research Institute, College of Science, Engineering, and Health, RMIT University

JoVE 51084

 JoVE Medicine

Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models

1Department of Otolaryngology - Head and Neck Surgery, University of Missouri, 2Department of Communication Science and Disorders, University of Missouri, 3Department of Medicine, University of Missouri

JoVE 52319

 JoVE Chemistry

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

1Chemical Sensing & Fuel Technology, Chemistry Division, U.S. Naval Research Laboratory, 2NOVA Research, Inc., 3Bio/Analytical Chemistry, Chemistry Division, U.S. Naval Research Laboratory, 4Navy Technology Center for Safety and Survivability, Chemistry Division, U.S. Naval Research Laboratory

JoVE 51938

 JoVE Developmental Biology

Generation of Parabiotic Zebrafish Embryos by Surgical Fusion of Developing Blastulae

1Division of Hematology/Oncology, Boston Children’s Hospital, 2Harvard Medical School, 3Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, 4Harvard Stem Cell Institute, 5Broad Institute of Massachusetts Institute of Technology, 6Howard Hughes Medical Institute, 7Division of Hematologic Malignancies, Dana-Farber Cancer Institute

JoVE 54168

 JoVE Biology

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

1Sorbonne Paris Cité, Laboratory “Hypoxia & Lung” EA2363, University Paris 13, 2UPMC Univ Paris 06, INSERM, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Universités, 3Laboratory of Excellence GR-Ex, 4Laboratory MOVE (EA 6314), University of Poitiers

JoVE 53613

 JoVE Biology

Visualizing Cytoplasmic Flow During Single-cell Wound Healing in Stentor coeruleus

1Physiology Course, Marine Biological Laboratory, 2Department of Biochemistry & Biophysics, University of California San Francisco, 3Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 4Max Planck Institute of Molecular Cell Biology and Genetics, 5Department of Physics, University of Illinois Urbana-Champaign

JoVE 50848

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