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Energy Transfer: The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of Forster resonance energy transfer.

Förster Resonance Energy Transfer (FRET)

JoVE 5696

Förster resonance energy transfer (FRET) is a phenomenon used to investigate close-range biochemical interactions. In FRET, a donor photoluminescent molecule can non-radiatively transfer energy to an acceptor molecule if their respective emission and absorbance spectra overlap. The amount of energy transferred—and consequently the overall emission of sample—depends on the proximity of an acceptor-donor pair of photoluminescent molecules. FRET analysis is combined with other biochemistry techniques to obtain detailed information of biomolecular structures and interactions from this “spectroscopic ruler.” This video covers the principles and concepts of FRET analysis. The procedure focuses on preparing samples for FRET and ways to present and interpret data. Finally, the applications include monitoring conformational and cellular processes by labeling parts of a cell or protein, monitoring enzyme reactions that alter protein structures, and using FRET to monitor aggregation of monomers expressed by cells. Förster Resonance Energy Transfer, or FRET, is a non-radiative transfer of energy between light-emitting molecules, and is often used to investigate close-range biochemical interactions. FRET only occurs when fluorescent molecules are spaced within 10 nm of each other. FRET analysis


Experimental Approach for Determining Semiconductor/liquid Junction Energetics by Operando Ambient-Pressure X-ray Photoelectron Spectroscopy

1Division of Chemistry and Chemical Engineering, California Institute of Technology, 2Joint Center for Artificial Photosynthesis, California Institute of Technology, 3Advanced Light Source, Lawrence Berkeley National Laboratory, 4Beckman Institute, California Institute of Technology

Video Coming Soon

JoVE 54129

 JoVE In-Press

Energy and Work

JoVE 10313

Source: Ketron Mitchell-Wynne, PhD, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA

This experiment demonstrates the work-energy principle. Energy is one of the most important concepts in science and is not simple to define. This experiment will deal with two different kinds of energy: gravitational potential energy and translational kinetic energy. Gravitational potential energy is defined as the energy an object possesses because of its placement in a gravitational field. Objects that are high above the ground are said to have large gravitational potential energy. An object that is in motion from one location to another has translational kinetic energy. The most crucial aspect of energy is that the sum of all types of energy is conserved. In other words, the total energy of a system before and after any event may be transferred to different kinds of energy, wholly or partly, but the total energy will be the same before and after the event. This lab will demonstrate this conservation. Energy can be defined as "the ability to do work," which relates mechanical energy with work. Flying projectiles that hit stationary objects do work on those stationary objects,

 Physics I

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 10344

Source: Ketron Mitchell-Wynne, PhD, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA

When a pot of water is placed on a hot stove, heat is said to "flow" from the stove to the water. When two or more objects are placed into thermal contact with each other, heat spontaneously flows from the hotter objects to the colder ones, or in the direction that tends to equalize the temperature between the objects. For example, when ice cubes are put in a cup of room-temperature water, heat from the water flows to the ice cubes and they begin to melt. Often, the term "heat" is used inconsistently, usually to simply refer to the temperature of something. In the context of thermodynamics, heat, like work, is defined as a transfer of energy. Heat is energy transferred from one object to another because of a difference in temperature. Furthermore, the total energy of any isolated thermodynamic system is constant-that is, energy can be transferred to and from different objects within the system and can be transformed to different types of energy, but energy cannot be created or destroyed. This is the first law of thermodynamics. It is very similar to the conservation of energy law discussed in another video, but in the

 Physics I

Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry

1Department of Materials Science and Engineering, Massachusetts Institute of Technology, 2Department of Biological Engineering, Massachusetts Institute of Technology, 3Department of Mechanical Engineering, Massachusetts Institute of Technology, 4Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School

JoVE 54201


Indacenodithienothiophene-Based Ternary Organic Solar Cells: Concept, Devices and Optoelectronic Analysis

1Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, 2Macromolecular Chemistry Group (buwmakro) and Institute for Polymer Technology, Bergische Universität Wuppertal, 3Department of Materials Science Engineering, University of Ioannina, 4Advent Technologies SA, 5National Hellenic Research Foundation (NHRF), 6Bavarian Center for Applied Energy Research (ZAE Bayern)

Video Coming Soon

JoVE 54007

 JoVE In-Press

Photoelectric Effect

JoVE 10413

Source: Yong P. Chen, PhD, Department of Physics && Astronomy, College of Science, Purdue University, West Lafayette, IN

Photoelectric effect refers to the emission of electrons from a metalwhen light is shining on it. In order for the electrons to be liberated from the metal, the frequency of the light needs to be sufficiently high such that the photons in the light have sufficient energy. This energy is proportional to the light frequency.The photoelectric effect provided the experimental evidence for the quantum of light that is known as photon. This experiment will demonstrate the photoelectric effect using a charged zinc metal subject to either a regular lamp light, or ultraviolet (UV) light with higher frequency and photon energy.The zinc plate will be connected to an electroscope, an instrument that can read the presence and relative amount of charges. The experiment will demonstrate that the UV light, but not the regular lamp, can discharge the negatively charged zinc by ejecting its excess electrons.Neither light source, however, can discharge positively charged zinc, consistent with the fact that electrons that are emitted in photoelectric effect.

 Physics II

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

1Institute for Solid State Research, IFW-Dresden, 2Institute of Metal Physics of National Academy of Sciences of Ukraine, 3Diamond Light Source LTD, 4Department of Physics, University of Johannesburg, 5CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Università di Salerno, 6Institute of Physics of Complex Matter, École Polytechnique Fédérale de Lausanne

JoVE 50129


Protocols for Implementing an Escherichia coli Based TX-TL Cell-Free Expression System for Synthetic Biology

1Department of Biology, California Institute of Technology, 2Department of Bioengineering, California Institute of Technology, 3Synthetic Biology Center, Department of Bioengineering, Massachusetts Institute of Technology, 4School of Physics and Astronomy, University of Minnesota

JoVE 50762


Proton Exchange Membrane Fuel Cells

JoVE 10022

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

The United States consumes a large amount of energy – the current rate is around 97.5 quadrillion BTUs annually. The vast majority (90%) of this energy comes from non-renewable fuel sources. This energy is used for electricity (39%), transportation (28%), industry (22%), and residential/commercial use (11%). As the world has a limited supply of these non-renewable sources, the United States (among others) is expanding the use of renewable energy sources to meet future energy needs. One of these sources is hydrogen. Hydrogen is considered a potential renewable fuel source, because it meets many important criteria: it’s available domestically, it has few harmful pollutants, it’s energy efficient, and it’s easy to harness. While hydrogen is the most abundant element in the universe, it is only found in compound form on Earth. For example, it is combined with oxygen in water as H2O. To be useful as a fuel, it needs to be in the form of H2 gas. Therefore, if hydrogen is to be used as a fuel for cars or other electronics, H2 needs to be made first. Thusly, hydrogen is often called an “energy carrier” rather than a “fuel.”

Electrochemically and Bioelectrochemically Induced Ammonium Recovery

1Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, 2Department of Environmental Sciences, Rutgers University

JoVE 52405


A Rapid Laser Probing Method Facilitates the Non-invasive and Contact-free Determination of Leaf Thermal Properties

1Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V., 2Institute for Molecular Biotechnology, RWTH Aachen University, 3Fraunhofer Institute for Laser Technology ILT, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.

JoVE 54835


A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery

1Joint Center for Energy Storage Research (JCESR), 2Energy & Environment Directorate, Pacific Northwest National Laboratory, 3Earth & Biological Systems Directorate, Pacific Northwest National Laboratory, 4Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory

JoVE 55171


Open Source High Content Analysis Utilizing Automated Fluorescence Lifetime Imaging Microscopy

1Photonics Group, Department of Physics, Imperial College London, 2Institute for Chemical Biology, Department of Chemistry, Imperial College London, 3MRC Clinical Sciences Centre, Hammersmith Hospital, 4Chemical Biology Section, Department of Chemistry, Imperial College London, 5Retroscreen Virology Ltd, 6Pfizer Global Research and Development, Pfizer Limited, Sandwich, Kent, UK, 7Centre for Histopathology, Imperial College London

JoVE 55119


Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

1Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 2Department of Chemistry, University of Illinois at Chicago, 3Stanford Synchrotron Radiation Lightsource, 4Haldor Topsøe A/S, 5PolyPlus Battery Company

JoVE 50594


Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

1Department of Mechanical Engineering, Massachusetts Institute of Technology, 2Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology, 3School of Engineering and Applied Sciences, Harvard University, 4Department of Materials Science and Engineering, Massachusetts Institute of Technology, 5Department of Chemistry & Chemical Biology, Harvard University

JoVE 52705


A Step Beyond BRET: Fluorescence by Unbound Excitation from Luminescence (FUEL)

1Plate-Forme d'Imagerie Dynamique, Imagopole, Institut Pasteur, 2Department of Radiation Oncology, Stanford School of Medicine, 3Service Hospitalier Frédéric Joliot, Institut d'Imagerie Biomédicale, 4Vanderbilt School of Medicine, 5The Walter & Eliza Hall Institute of Medical Research, 6Unité INSERM U786, Institut Pasteur, 7Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur

JoVE 51549


Conducting Reactions Below Room Temperature

JoVE 10224

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

 Organic Chemistry

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