Show Advanced Search

REFINE YOUR SEARCH:

Containing Text
- - -
+
Filter by author or institution
GO
Filter by publication date
From:
October, 2006
Until:
Today
Filter by journal section

Filter by science education

 
 
Potassium Chloride: A white crystal or crystalline powder used in Buffers; Fertilizers; and Explosives. It can be used to replenish Electrolytes and restore Water-electrolyte balance in treating Hypokalemia.

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

Soil Nutrient Analysis: Nitrogen, Phosphorus, and Potassium

JoVE 10077

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

In this experiment, three soil macronutrients are chemically extracted, combined with color-based reagents, then analyzed using color to determine the nutrient concentration present in the soil sample.

Nitrogen, phosphorus, and potassium are the main components of soil fertilizer. These methods isolate each nutrient from the soil into a solution that can be analyzed using turbidity and color to determine the concentration of nutrients present in the soil sample. Knowing present concentration informs environmental scientists of a nutrient deficiency or surplus in soils used to support plant production, and also provides general insight into basic biogeochemical cycles of an ecosystem.


 Environmental Science

Electroplating of Thin Films

JoVE 10489

Source: Logan G. Kiefer, Andrew R. Falkowski, and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT

Electroplating is a process that uses electric current to reduce dissolved metal cations so that they form a thin coating on an electrode. Other thin film deposition techniques include chemical vapor deposition (CVD), spin coating, dip coating, and sputter deposition among others. CVD uses a gas-phase precursor of the element to be deposited. Spin coating spreads the liquid precursor centrifugally. Dip coating is similar to spin coating, but rather than spinning the liquid precursor, the substrate is completely submerged in it. Sputtering uses plasma to remove the desired material from a target, which then plates the substrate. Techniques such as CVD or sputtering produce very high quality films but do so very slowly and at high cost since these techniques typically require a vacuum atmosphere and small sample size. Electrodeposition doesn't rely on a vacuum atmosphere which greatly reduces the cost and increases scalability. In addition, relatively high rates of deposition can be achieved with electrodeposition.


 Materials Engineering

PCR: The Polymerase Chain Reaction

JoVE 5056

The polymerase chain reaction, or PCR, is a technique used to amplify DNA through thermocycling – cyles of temperature changes at fixed time intervals. Using a thermostable DNA polymerase, PCR can create numerous copies of DNA from DNA building blocks called dinucleoside triphosphates or dNTPs. There are three steps in PCR: denaturation, annealing, and elongation. Denaturation is the first step in the cycle and causes the DNA to melt by disrupting hydrogen bonds between the bases resulting in single-stranded DNA. Annealing lowers the temperature enough to allow the binding of oligonucleotide primers to the DNA template. During the elongation step DNA polymerase will synthesize new double-stranded DNA. This video provides an introduction to the PCR procedure. The basic principles of PCR are described as well as a step-by-step procedure for setting up a generalized PCR reaction. The video shows the necessary components for a PCR reaction, includes instruction for primer design, and provides helpful hints for ensuring successful PCR reactions.


 Basic Methods in Cellular and Molecular Biology

Community DNA Extraction from Bacterial Colonies

JoVE 10218

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Luisa Ikner

Traditional methods of analysis for microbial communities within soils have usually involved either cultural assays utilizing dilution and plating methodology on selective and differential media or direct count assays. Direct counts offer information about the total number of bacteria present, but give no information about the number or diversity of populations present within the community. Plate counts allow enumeration of total cultural or selected cultural populations, and hence provide information on the different populations present. However, since less than 1% of soil bacteria are readily culturable, cultural information offers only a piece of the picture. The actual fraction of the community that can be cultured depends on the medium chosen for cultural counts. Any single medium will select for the populations that are best suited to that particular medium. In recent years, the advantages of studying community DNA extracted from soil samples have become apparent. This nonculture-based approach is thought to be more representative of the actual community present than culture-based approaches. In addition to providing information about the types of populations present, this


 Environmental Microbiology

Conversion of Fatty Acid Methyl Esters by Saponification for Uk'37 Paleothermometry

JoVE 10158

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds or, if interested in many, may need to remove unwanted constituents that are"in the way" or co-eluting. For example, the concentrations of individual compounds in a sample are often determined on a gas chromatograph coupled to a flame-ionizing detector (GC-FID), because the relationship between FID response (in pA) and the amount of compound in a sample (e.g., ng/µL) is both linear and sensitive. The GC portion of the instrument separates different compounds in a sample based on their boiling point, chemical structure, and affinity with a solid phase that can change according to application. The result is a chromatogram (Figure 1), showing the separation of different chemical constituents in time, as well as their relative concentration (calculated as the area under the curve). However, sometimes more than one compound elutes off the GC at a time (Figure 1). In this case, sample purification is required before compounds can be confidently quantified


 Earth Science

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


 Biology

Preparing and Administering Intermittent Intravenous Medications with an Infusion Pump

JoVE 10277

Source: Madeline Lassche, MSNEd, RN and Katie Baraki, MSN, RN, College of Nursing, University of Utah, UT

Primary intermittent intravenous (IV) infusions are delivered alone as volume-controlled infusions, while secondary infusions are delivered with another IV fluid, usually maintenance fluids. Intermittent infusions are delivered over a specific amount of time, which is dictated by the type of medication, such as IV antibiotics. High-volume IV medications, anywhere from 50- to 500-mL infusions, are typically delivered using an infusion pump as either primary or secondary infusions. Infusion pumps deliver IV fluids in a volume-controlled manner, keeping medication side effects to a minimum and helping to prevent nurse medication errors. Careful review of the medication compatibility with maintenance fluids using an approved medication drug guide, pharmacy recommendations in the Medication Administration Record (MAR), and physician orders must be assessed prior to delivering an IV medication. This review will determine if primary or secondary delivery is appropriate based on the risk for patient harm, such as for concentrated electrolyte preparations like potassium. Certain medical conditions that preclude oral fluid intake, specific medication preparations, or situations that require an inc


 Nursing Skills

Standardized Measurement of Nasal Membrane Transepithelial Potential Difference (NPD)

1Department of Medicine and the Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, 2Department of Pulmonology and Tuberculosis, University Medical Center Utrecht, 3Center for Experimental Medicine, Queens University, Northern Ireland, 4Hadassah Hebrew University Medical Center, Jerusalem, 5Centro Fibrosi Cistica, Azienda Ospedaliera Universitaria Integrata, 6Service de Pneumologie et Allergologie Pédiatriques and Center de Ressources et de Compétence de la Mucoviscidose, Hôpital Necker Enfants Malades, 7INSERM U 1151, Institut Necker Enfants Malades

JoVE 57006


 Medicine

Cleaning Glassware

JoVE 10342

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

Organic synthesis is about transforming a readily available reagent into a more valuable product. Having clean glassware is crucial for the efficiency of this process. Dirty glassware can potentially affect the reaction and make isolation of the final product more challenging. Thus, a synthetic chemist must keep the glassware spotless. The methods described here will detail different glass cleaning techniques that are regularly used to remove organics, metals, grease, and salts.


 Organic Chemistry II

Ion-Exchange Chromatography

JoVE 10269

Source: Laboratory of Dr. B. Jill Venton - University of Virginia

Ion-exchange chromatography is a type of chromatography that separates analytes based on charge. A column is used that is filled with a charged stationary phase on a solid support, called an ion-exchange resin. Strong cation-exchange chromatography preferentially separates out cations by using a negatively-charged resin while strong anion-exchange chromatography preferentially selects out anions by using a positively-charged resin. This type of chromatography is popular for sample preparation, for example in the cleanup of proteins or nucleic acid samples. Ion-exchange chromatography is a two-step process. In the first step, the sample is loaded onto the column in a loading buffer. The binding of the charged sample to the column resin is based on ionic interactions of the resin to attract the sample of the opposite charge. Thus, charged samples of opposite polarity to the resin are strongly bound. Other molecules that are not charged or are of the opposite charge are not bound and are washed through the column. The second step is to elute the analyte that is bound to the resin. This is accomplished with a salt gradient, where the amount of salt in the buffer is slowly increased. Fractions are collected at the end of the column as


 Analytical Chemistry

Removal of Exogenous Materials from the Outer Portion of Frozen Cores to Investigate the Ancient Biological Communities Harbored Inside

1Biogeochemical Sciences Branch, Cold Regions Research and Engineering Laboratory, US Army Engineer Research & Development Center, Hanover, NH, 2Environmental Processes Branch, Environmental Laboratory, US Army Engineer Research & Development Center, Vicksburg, MS, 3Terrestrial and Cryospheric Scienes Branch, Cold Regions Research and Engineering Laboratory, US Army Engineer Research & Development Center, Hanover, NH, 4Biogeochemical Sciences Branch, Cold Regions Research and Engineering Laboratory, US Army Engineer Research & Development Center, Fairbanks, AK

JoVE 54091


 Biology

Generation and On-Demand Initiation of Acute Ictal Activity in Rodent and Human Tissue

1Division of Fundamental Neurobiology, Krembil Research Institute, 2Institute of Medical Science, Faculty of Medicine, University of Toronto, 3Institute of Biomaterials and Biomedical Engineering, University of Toronto, 4Division of Neurosurgery, Department of Surgery, University of Toronto, 5Division of Neurology, Department of Medicine, University of Toronto, 6Department of Physiology, University of Toronto

Video Coming Soon

JoVE 57952


 JoVE In-Press

Characterizing Electron Transport through Living Biofilms

1Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 2George Mason University, 3Chemistry Division, Naval Research Laboratory, 4Departments of Physics, Biological Sciences, and Chemistry, University of Southern California, 5Department of Chemical Engineering and Materials Science, Michigan State University

JoVE 54671


 Chemistry

Performing 1D Thin Layer Chromatography

JoVE 5499

Source: Laboratory of Dr. Yuri Bolshan — University of Ontario Institute of Technology

Thin layer chromatography (TLC) is a chromatographic method used to separate mixtures of non-volatile compounds. A TLC plate consists of a thin layer of adsorbent material (the stationary phase) fixed to an appropriate solid support such as plastic, aluminum, or glass1. The sample(s) and reference compound(s) are dissolved in an appropriate solvent and applied near the bottom edge of the TLC plate in small spots. The TLC plate is developed by immersing the bottom edge in the developing solvent consisting of an appropriate mobile phase. Capillary action allows the mobile phase to move up the adsorbent layer. As the solvent moves up the TLC plate, it carries with it the components of each spot and separates them based on their physical interactions with the mobile and stationary phases.


 Organic Chemistry

Phosphopeptide Enrichment Coupled with Label-free Quantitative Mass Spectrometry to Investigate the Phosphoproteome in Prostate Cancer

1Graduate Program in Cellular and Molecular Pharmacology, School of Graduate Studies, Rutgers University, The State University of New Jersey, 2Graduate Program in Quantitative Biomedicine, School of Graduate Studies, Rutgers University, The State University of New Jersey, 3Department of Medicine, Division of Medical Oncology, Rutgers Robert Wood Johnson Medical School, 4Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, Jonsson Comprehensive Cancer Center, UCLA Metabolomics Center, and California NanoSystems Institute, David Geffen School of Medicine, University of California, Los Angeles, 5Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, 6Pharmacology, Rutgers Robert Wood Johnson Medical School, 7Cancer Metabolism and Growth Program, Rutgers Cancer Institute of New Jersey

JoVE 57996


 Cancer Research

Biofunctionalized Prussian Blue Nanoparticles for Multimodal Molecular Imaging Applications

1The Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Medical Center, 2Fischell Department of Bioengineering, University of Maryland, 3Department of Radiology, George Washington University, 4Department of Pediatrics, George Washington University

JoVE 52621


 Bioengineering

12345678914
More Results...