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Carbon Nanotubes 
Julie MacPherson talks about her work with Carbon Nanotubes and Atomic Force Microscopy. Carbon nanotubes (CNTs) are allotropes of carbon. A single-walled carbon nanotube (SWNT) is a one-atom thick sheet of graphite (called graphene) rolled up into a seamless cylinder with diameter on the order of a nanometer. This results in a nanostructure where the length-to-diameter ratio exceeds 1,000,000. Such cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. Nanotubes are members of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is in the order of a few nanometers (approximately 1/50,000th of the width of a human hair), while they can be up to several millimeters in length. Nanotubes are categorized as single-wal...
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Added By - scienceforum
Subject - Nanoscience and Nanotechnology
Document Type -
Video Duration - 00:03:32


Fuel Cells 
In essence, a fuel cell works by catalysis, separating the component electrons and protons of the reactant fuel, and forcing the electrons to travel through a circuit, hence converting them to electrical power. Another catalytic process takes the electrons back in, combining them with the protons and the oxidant to form waste products (typically simple compounds like water and carbon dioxide). In the archetypal hydrogen–oxygen proton exchange membrane fuel cell (PEMFC) design, a proton-conducting polymer membrane, (the electrolyte), separates the anode and cathode sides. This was called a "solid polymer electrolyte fuel cell" (SPEFC) in the early 1970s, before the proton exchange mechanism was well-understood. (Notice that "polymer electrolyte membrane" and "proton exchange membrane" result in the same acronym.) On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates into protons and electrons. The protons are conducted through the membrane to the cathode, but the electrons are forced to travel in an external circuit (supplying power) because the membrane is electrically insulating. On the cathode catalyst, oxygen molecules react with the electrons (which have traveled through the external circu...
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Added By - sidpatel
Subject - Energy
Document Type - White Board
Video Duration - 00:07:02


Chemistry 3B - Lecture 03: Electronic Spectro... 
Chemistry 3B: Chemical Structure and Reactivity. Spring 2006. Professor Peter Vollhardt. Chemistry 3B represents the second semester of the standard organic chemistry series at UC Berkeley. It covers conjugation, aromatic chemistry, carbonyl compounds, carbohydrates, amines, carboxylic acids, amino acids, peptides, proteins, and nucleic acid chemistry. Ultraviolet spectroscopy and mass spectrometry will be introduced. Organic chemistry is a specific discipline within the subject of chemistry. It is the scientific study of the structure, properties, composition, reactions, and preparation of chemical compounds of carbon and hydrogen, which may contain any number of other elements, such as nitrogen
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Added By - A Ghosh
Subject - Chemistry and Chemical Engineering
Document Type - Course Lecture
Video Duration - 01:14:54


Solid Oxide Fuel Cells 

A solid oxide fuel cell (SOFC) is an electrochemical conversion device that produces electricity directly from fuel. Fuel cells are characterized by their electrolyte material and, as the name implies, the SOFC has a solid oxide, or ceramic, electrolyte. Ceramic fuel cells operate at much higher temperatures than polymer based ones.

Solid oxide fuel cells are intended mainly for stationary applications with an output from 100 W to 2 MW. They work at very high temperatures, typically between 700 and 1,000°C. Their off-gases can be used to fire a secondary gas turbine to improve electrical efficiency. This enables efficiency to reach as much as 90% in these hybrid systems, called combined heat and power (CHP) device. In these cells,  

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Added By - sidpatel
Subject - Energy
Document Type - White Board
Video Duration - 00:09:12


Customized Y-Shaped Nanotubes Can Compute 
Researchers at UC San Diego and Clemson University have discovered that specially synthesized carbon nanotube structures exhibit electronic properties that are improved over conventional transistors used in computers. In a paper published* in the September issue of Nature Materials and released online on August 14, UCSD Mechanical and Aerospace Engineering professors Prabhakar Bandaru and Sungho Jin, graduate student Chiara Daraio, and Clemson physicist Apparao M. Rao reported that Y-shaped nanotubes behave as electronic switches similar to conventional MOS (metal oxide semiconductor) transistors, the workhorses of modern microprocessors, digital memory, and application-specific integrated circuits.
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Added By - autocrawler
Subject - Nanoscience and Nanotechnology
Document Type - Demonstration
Video Duration - 00:03:39


CO2 emissions and climate change 
Global warming is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation. The global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 year period ending in 2005.[1] The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations"[1] via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.[2][3] These basic conclusions have been endorsed by at least 30 scientific societies and academies of science,[4] including all of the national academies of science of the major industrialized countries.[5][6][7] While individual scientists have voiced disagreement with the conclusions of the IPCC[8], the overwhelming majority of scientists working on climate change are in agreement with the conclusions.
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Added By - publichealth
Subject - Public Health
Document Type - Discussion
Video Duration - 00:01:55


Blood: Path of a Red Blood Cell 

Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen from the lungs or gills to body tissues via the blood.

Human red blood cellsRed blood cells are also known as RBCs, haematids or erythrocytes (from Greek erythros for "red" and kytos for "hollow", with cyte nowadays translated as "cell"). RBCs should more properly be referred to as "corpuscles" rather than "cells", as a cells contains a nucleus while mature RBCs in mammals do not.

A schistocyte is a red blood cell undergoing fragmentation, or a fragmented part of a red blood cell.

Erythrocytes consist mainly of hemoglobin, a complex molecule containing heme groups whose iron atoms temporarily link to oxygen molecules in the lungs or gills and release them throughout the body. Oxygen can easily diffuse through the red blood cell's cell membrane. Hemoglobin also carries some of the waste product carbon dioxide back from the tissues. (In humans, less than 2% of the total oxygen, and most of the carbon dioxide, is held in solution in the blood plasma). A related compound, myoglobin, acts to store oxygen in muscle...

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Added By - 123456
Subject - Biology
Document Type - Documentary
Video Duration - 00:00:02


Structural Collapse: the classic case -Tacoma... 

The collapse of the bridge was recorded on film by Barney Elliott, owner of a local camera shop, and shows Leonard Coatsworth leaving the bridge after exiting his car. In 1998, The Tacoma Narrows Bridge Collapse was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant." This footage is still shown to engineering, architecture, and physics students as a cautionary tale.[9] Elliot's original films of the construction and collapse of the bridge were shot on 16mm  

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Added By - justin
Subject - Civil and Environmental Enginering
Document Type - Demonstration
Video Duration - 00:04:12

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