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Silver Nitrate: A silver salt with powerful germicidal activity. It has been used topically to prevent Ophthalmia neonatorum.
 Science Education: Essentials of General Chemistry

Le Châtelier's Principle

JoVE Science Education

Source: Laboratory of Dr. Lynne O'Connell — Boston College

When the conditions of a system at equilibrium are altered, the system responds in such a way as to maintain the equilibrium. In 1888, Henri-Lewis Le Châtelier described this phenomenon in a principle that states, "When a change in temperature, pressure, or concentration disturbs a system in chemical equilibrium, the change will be counteracted by an alteration in the equilibrium composition." This experiment demonstrates Le Châtelier's principle at work in a reversible reaction between iron(III) ion and thiocyanate ion, which produces iron(III) thiocyante ion: Fe3+(aq) + SCN- (aq) FeSCN2+ (aq) The concentration of one of the ions is altered either by directly adding a quantity of one ion to the solution or by selectively removing an ion from the solution through formation of an insoluble salt. Observations of color changes indicate whether the equilibrium has shifted to favor formation of the products or the reactants. In addition, the effect of a temperature change on the solution at equilibrium can be obs

 JoVE Medicine

Calcification of Vascular Smooth Muscle Cells and Imaging of Aortic Calcification and Inflammation

1Anesthesia Center for Critical Care Research of the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, 2Cardiovascular Research Center and Cardiology Division of the Department of Medicine, Massachusetts General Hospital, 3Cardiovascular Division, Brigham and Women's Hospital, 4Harvard Medical School, 5Department of Anesthesiology, Uniklinik RWTH Aachen, RWTH Aachen University, 6Center for Immunology and Inflammatory Diseases and the Division of Rheumatology, Allergy, and Immunology of the Department of Medicine, Massachusetts General Hospital


JoVE 54017

 JoVE Bioengineering

Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis

1The School of Plant Sciences, University of Arizona, 2Department of Chemical Engineering and Materials Science, DOE Great Lakes Bioenergy Research Center, Michigan State University, 3The Institute for Sustainable and Renewable Resources, The Institute for Advanced Learning and Research, 4Department of Plant, Soil and Microbial Sciences, Michigan State University


JoVE 51340

 JoVE Bioengineering

Planar and Three-Dimensional Printing of Conductive Inks

1Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 2Center for Micro- and Nanotechnology, Lawrence Livermore National Laboratory, 3Presently at the Interdisciplinary Center for Wide Band-gap Semiconductors, University Of California Santa Barbara


JoVE 3189

 JoVE Medicine

From a 2DE-Gel Spot to Protein Function: Lesson Learned From HS1 in Chronic Lymphocytic Leukemia

1Division of Molecular Oncology, IRCCS, San Raffaele Scientific Institute, 2Department of Haemato-Oncology, King's College London, 3IFOM, FIRC Institute of Molecular Oncology, 4Università Vita-Salute San Raffaele


JoVE 51942

 JoVE Biology

Manual Isolation of Adipose-derived Stem Cells from Human Lipoaspirates

1Cytori Therapeutics Inc, 2Division of Cardiac Surgery, Department of Surgery, David Geffen School of Medicine at UCLA, 3Division of Plastic and Reconstructive Surgery, Department of Surgery, David Geffen School of Medicine at UCLA, 4Department of Orthopedic Surgery, David Geffen School of Medicine at UCLA, 5Regenerative Bioengineering and Repair Laboratory, David Geffen School of Medicine at UCLA


JoVE 50585

 Science Education: Essentials of General Chemistry

Determining the Solubility Rules of Ionic Compounds

JoVE Science Education

Source: Laboratory of Dr. Neal Abrams — SUNY College of Environmental Science and Forestry

An ionic compound's solubility can be determined via qualitative analysis. Qualitative analysis is a branch of analytical chemistry that uses chemical properties and reactions to identify the cation or anion present in a chemical compound. While the chemical reactions rely on known solubility rules, those same rules can be determined by identifying the products that form. Qualitative analysis is not typically done in modern industrial chemistry labs, but it can be used easily in the field without the need of sophisticated instrumentation. Qualitative analysis also focuses on understanding ionic and net ionic reactions as well as organizing data into a flow chart to explain observations and make definitive conclusions. Many cations have similar chemical properties, as do the anion counterparts. Correct identification requires careful separation and analysis to systematically identify the ions present in a solution. It is important to understand acid/base properties, ionic equilibria, redox reactions, and pH properties to identify ions successfully. While there is a qualitative test for virtually every elemental and polyatomic ion, the identification process typically begi

 JoVE Chemistry

Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment

1Empa - Swiss Federal Laboratories for Materials Science and Technology, 2Institute of Chemical and Bioengineering, Department of Chemistry and Applied Bioscience, ETH Zurich, 3ICN2-Institut Catala de Nanociencia i Nanotecnologia, 4WITec GmbH, 5Institut de Ciència de Materials de Barcelona, 6School of Chemistry, The University of Nottingham


JoVE 54193

 JoVE Neuroscience

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

1Hans Berger Department of Neurology, Jena University Hospital, 2Immunology, Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, 3Institute of Diagnostic and Interventional Radiology, Medical Physics Group, Jena University Hospital


JoVE 51274

 Science Education: Essentials of Analytical Chemistry

Method of Standard Addition

JoVE Science Education

Source: Laboratory of Dr. Paul Bower - Purdue University

The method of standard additions is a quantitative analysis method, which is often used when the sample of interest has multiple components that result in matrix effects, where the additional components may either reduce or enhance the analyte absorbance signal. That results in significant errors in the analysis results. Standard additions are commonly used to eliminate matrix effects from a measurement, since it is assumed that the matrix affects all of the solutions equally. Additionally, it is used to correct for the chemical phase separations performed in the extraction process. The method is performed by reading the experimental (in this case fluorescent) intensity of the unknown solution and then by measuring the intensity of the unknown with varying amounts of known standard added. The data are plotted as fluorescence intensity vs. the amount of the standard added (the unknown itself, with no standard added, is plotted ON the y-axis). The least squares line intersects the x-axis at the negative of the concentration of the unknown, as shown in Figure 1. Figure 1

 JoVE Biology

An Alternant Method to the Traditional NASA Hindlimb Unloading Model in Mice

1Physical Therapy Department, University of Missouri, Columbia, 2Biomedical Sciences Department, University of Missouri, Columbia


JoVE 2467

 Science Education: Essentials of Organic Chemistry

Separation of Mixtures via Precipitation

JoVE Science Education

Source: Laboratory of Dr. Ana J. García-Sáez — University of Tübingen

Most samples of interest are mixtures of many different components. Sample preparation, a key step in the analytical process, removes interferences that may affect the analysis. As such, developing separation techniques is an important endeavor not just in academia, but also in industry.  One way to separate mixtures is to use their solubility properties. In this short paper, we will deal with aqueous solutions. The solubility of a compound of interest depends on (1) ionic strength of solution, (2) pH, and (3) temperature. By manipulating with these three factors, a condition in which the compound is insoluble can be used to remove the compound of interest from the rest of the sample.1

 JoVE Bioengineering

Mesenchymal Stromal Cell Culture and Delivery in Autologous Conditions: A Smart Approach for Orthopedic Applications

1Dept. of Clinical and Experimental Medicine, University of Pisa, 2OtoLab, Azienda Ospedaliero-Universitaria Pisana (AOUP), 3Dept. of Civil and Industrial Engineering, University of Pisa, 4Immunohematology Operative Unit, Azienda Ospedaliero-Universitaria Pisana (AOUP), 5Dept. Of Surgical, Medical, Molecular Pathology and Emergency Medicine, University of Pisa, 6II Orthopedic and Traumatologic Clinic, Azienda Ospedaliero-Universitaria Pisana (AOUP)


JoVE 54845

 JoVE Bioengineering

Multi-analyte Biochip (MAB) Based on All-solid-state Ion-selective Electrodes (ASSISE) for Physiological Research

1Department of Agricultural and Biological Engineering, Birck-Bindley Physiological Sensing Facility, Purdue University, 2NASA Ames Research Center, 3Department of Chemistry, Pennsylvania State University Hazleton, 4Cooley LLP, 5NASA Life and Physical Sciences, Human Exploration and Operations Mission Directorate, NASA Headquarters


JoVE 50020

 JoVE In-Press

Preparation of Giant Vesicles Exhibiting Visible-light-induced Morphological Changes

1Department of Applied Chemistry, School of Applied Science, National Defense Academy of Japan, 2Department of Applied Physics, School of Applied Science, National Defense Academy of Japan, 3Department of Materials Science and Technology, Faculty of Engineering, Niigata University

Video Coming Soon

JoVE 54817

 JoVE Biology

Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique

1Department of Dermatology, Institute for Regenerative Cures, University of California, Davis, 2Departamento de Biologia, Centro de Biologia Molecular e Ambiental, Universidade do Minho, 3Department of Neurology and Center for Neuroscience, University of California, Davis Imaging of Dementia and Aging Laboratory, 4Department of Ophthalmology, Institute for Regenerative Cures, University of California, Davis


JoVE 52782

 JoVE Bioengineering

Preparation and Photoacoustic Analysis of Cellular Vehicles Containing Gold Nanorods

1Institute of Applied Physics, Italian National Research Council, 2Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firenze, 3Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, 4Department of Pharmacy and Biotechnology, University of Bologna


JoVE 53328

 Science Education: Essentials of Biochemistry

Two-Dimensional Gel Electrophoresis

JoVE Science Education

Two-dimensional gel electrophoresis (2DGE) is a technique that can resolve thousands of biomolecules from a mixture. This technique involves two distinct separation methods that have been coupled together: isoelectric focusing (IEF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). This physically separates compounds across two axes of a gel by their isoelectric points (an electrochemical property) and their molecular weights. The procedure in this video covers the main concepts of 2DGE and a general procedure for characterizing the composition of a complex protein solution. Three examples of this technique are shown in the applications section, including biomarker detection for disease initiation and progress, monitoring treatment in patients, and the study of proteins following posttranslational modification (PTM). Two-dimensional, or 2D, gel electrophoresis is a technique utilizing two distinct separation methods which can separate thousands of proteins from a single mixture. One of the techniques, SDS-PAGE or sodium dodecyl sulfate polyacrylamide gel electrophoresis, cannot fully separate complex mixtures alone. 2D gel electrophoresis couples the SDS-PAGE to a second method, isoelectric focusing or IEF, which separates based on isoelectric points, allowing for the resolution of potentially a

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