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Silver Nitrate: A silver salt with powerful germicidal activity. It has been used topically to prevent Ophthalmia neonatorum.

Nucleophilic Substitution

JoVE 10465

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA

Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom.

SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to visualize the subtle differences between an SN1 and SN2 reaction and what factors help to speed up each type of nucleophilic substitution reaction. The first section will focus on reactions that will help to better understand and learn about nucleophilic substitution reactions. The second section will focus on a real-world example of a substitution reaction.


 Organic Chemistry II

Le Châtelier's Principle

JoVE 10138

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


 General Chemistry

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


 Medicine

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


 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


 Bioengineering

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


 Medicine

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


 Chemistry

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


 Biology

Determining the Solubility Rules of Ionic Compounds

JoVE 10197

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


 General 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


 Chemistry

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


 Neuroscience

Method of Standard Addition

JoVE 10201

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

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


 Biology

Separation of Mixtures via Precipitation

JoVE 5558

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


 Organic Chemistry

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


 Bioengineering

Well-Aligned Vertically Oriented ZnO Nanorod Arrays and Their Application in Inverted Small Molecule Solar Cells

1Department of Electrical Engineering, National United University, 2Research Center of Applied Science, Academia Sinica, 3Department of Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 4Department of Electronic Engineering, Chung Yuan Christian University

Video Coming Soon

JoVE 56149


 JoVE In-Press

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


 Bioengineering

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