Name: how maldi-tof reads biomolecules
Uploaded: 2023-04-30T06:31:26.000Z
Duration: 7 min 27 s
Channel: JoVE

K12 Standards

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New York State Science Learning Standards

High School

Physical Science

HS. Waves and Electromagnetic Radiation

HS-PS4-5.

MALDI-TOF Mass Spectrometry

基质辅助激光解吸电离（MALDI）是一种适用于生物大分子分析的质谱离子源。该技术并不直接对气态化合物进行电离，而是将样品嵌入基质中，再用激光照射。基质吸收大部分能量，随后将部分能量传递给样品，从而使其电离。产生的样品离子可通过飞行时间分析器（TOF）进行鉴定。
本视频介绍了基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）的基本原理，包括基质的选择以及飞行时间（TOF）如何用于确定质荷比。该实验流程演示了MALDI靶板的制备、样品在靶板上的点样，以及飞行时间质谱仪的操作。在最后部分，展示了该技术的应用与变体，包括全细胞分析、复杂生物样品的表征，以及电喷雾电离技术。

基质辅助激光解吸电离飞行时间质谱

基质辅助激光解吸电离（MALDI）是一种适用于生物大分子分析的质谱电离源。该技术并非对气态化合物进行电离，而是将样品嵌入基质中，再用激光照射。基质吸收大部分能量，随后将部分能量传递给样品，使其发生电离。电离后的样品离子可通过飞行时间分析器（TOF）进行鉴定。
本视频介绍了基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）的基本原理，包括基质的选择以及飞行时间（TOF）如何用于确定质荷比。该实验流程演示了MALDI靶板的制备、样品在靶板上的点样，以及飞行时间质谱仪的操作。在最后部分，展示了该技术的应用与变体，包括全细胞分析、复杂生物样品的表征，以及电喷雾电离技术。
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基质辅助激光解吸电离（MALDI）是一种适用于生物大分子分析的质谱电离源。大多数电离源在电离过程中会破坏大分子量且结构脆弱的生物分子的结构信息，而 MALDI 能在将分子加速进入质量分析器的同时保持其结构完整性和相关信息。质量分析器根据化合物的大小和电荷对其进行分离。与 MALDI 最常联用的质量分析器是飞行时间（TOF）质量分析器。本视频将介绍 MALDI 电离的基本原理、通用实验操作流程及其在生物化学中的一些应用。
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要使质谱技术发挥作用，分子必须被电离并转化为气态。在基质辅助激光解吸电离（MALDI）中，样品被包埋于一种基质中，该基质通常为含有芳香环和共轭双键的有机化合物。
当激光脉冲照射该混合物时，基质吸收大部分能量，迅速升温并从表面解吸或释放出来。被激发的基质将部分能量传递给生物大分子，使其解吸并随后发生离子化。
MALDI 通常与飞行时间（TOF）质量分析器联用。电场赋予离子动能，推动其进入一个无电场区域，称为漂移管。离子在管中运动的速度与其质荷比相关，因此较重的粒子在仪器中移动得更慢。位于管末端的检测器测量每个离子的飞行时间。结合已知的漂移管长度和所加电场强度，即可推算出每个离子的质荷比。
这种信号强度对质荷比的图谱，称为质谱图，可与已有的谱图数据库进行比对。若未找到匹配项，则可通过串联质谱等进一步技术对分子进行鉴定。有关更多信息，请参见本合集中关于该主题的视频。
在了解了 MALDI-TOF 的基本原理之后，接下来让我们观察其在实验室中的实际操作过程。
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在开始实验之前，必须考虑用于样品解吸的基质选择。理想的基质应能吸收激光能量、在真空条件下稳定、不与目标分子发生反应，并具备良好的解吸能力。根据样品的不同，所选用的基质也有所差异。对于大分子蛋白质，CHCA与DHB的组合相较于单独使用任一种基质，可实现更佳的峰分离效果，即更高的分辨率。
有多种方法可用于样品制备。我们将展示一种被称为 &#34;双层&#34;，或 &#34;三明治&#34; 方法。首先，使用超纯试剂清洁MALDI板，因为质谱对污染极为敏感。用惰性气体气流吹干该板。
接下来，配制饱和基质溶液，通常使用有机溶剂。将该溶液涂抹于MALDI靶板上并干燥。随后制备第二种含有三氟乙酸（trifluoroacetic acid，TFA）的饱和基质溶液。TFA有助于离子进入气相。
接下来，将样品溶液加至干燥的基质斑点上方。再将含有TFA的基质溶液加至样品上，从而完成基质的制备 &#34;三明治&#34;可在低倍显微镜下验证斑点的均一性。
接种校准标准品，该标准品为含有已知质量范围的混合物，用于关联飞行时间与质荷比（m/z）。最后，仅接种基质作为阴性对照。
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为分析样品点，将目标板放入仪器中。确保无任何残留物，以形成严密的真空环境。在软件中选择标准品、阴性对照以及待测样品，并使用正确的标识对样品点进行标记。
可调节离子源和透镜电压以优化分析性能，具体设置取决于仪器型号和样品特性。聚焦于标准品点，并使用软件对仪器进行校准。
随后，采集各个样品点的质谱数据。在每个样品点上尝试多个不同位置，以最大限度提高所采集数据的质量。完成后，可取出MALDI靶板，经清洗后重复使用。
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在回顾了一种实验流程之后，让我们来看看 MALDI 的一些应用方式，以及另一种不同的电离技术。
除了生物大分子之外，MALDI 还可用于分析活细胞。巨噬细胞是一类免疫细胞，其形态会根据微环境的不同而呈现多种不同类型。在将这些细胞暴露于各种信号分子或细胞因子后，可直接将其加入样品靶板并进行分析。所获得的 MALDI 谱图可作为独特的&#34;指纹&#34;，具体谱图特征取决于所使用的细胞因子种类。
对于哺乳动物皮脂分泌物等复杂的生物样品，在进行 MALDI 分析前需先进行纯化处理。薄层色谱法（TLC）是一种基于化合物极性的纯化技术。通过该方法从 TLC 板上收集目标化合物，经纯化后转移至 MALDI 基质中。所得谱图可用于验证从哺乳动物皮脂分泌物中分离出的生物分子的身份和纯度。
另一种常用于生物分子的电离源是电喷雾电离（ESI）。在该方法中，样品被直接注入仪器，施加高电压后形成带电液滴的气溶胶。随着液滴中溶剂的蒸发，电荷逐渐转移至样品分子，直至其完全转变为气相。ESI 无需点样步骤，样品可直接注入仪器。然而，ESI 对缓冲液成分及其他污染物更为敏感，因此相比之下，MALDI 具有更强的抗干扰能力。
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您刚刚观看了 JoVE 关于基质辅助激光解吸电离质谱（MALDI 质谱）的视频。本视频介绍了该仪器背后的原理，概述了一般操作流程，并讲解了该技术的一些应用。感谢观看！
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基质辅助激光解吸电离（MALDI）是一种适用于生物大分子分析的质谱离子源。与直接电离……

基质辅助激光解吸电离（MALDI）是一种适用于生物大分子分析的质谱电离源。大多数电离源在电离过程中会破坏大分子量且结构脆弱的生物分子的结构信息，而 MALDI 能在将分子加速进入质量分析器的同时保持其结构完整性和相关信息。质量分析器根据化合物的大小和电荷对其进行分离。与 MALDI 最常联用的质量分析器是飞行时间（TOF）质量分析器。本视频将介绍 MALDI 电离的基本原理、通用操作流程以及其在生物化学中的一些应用。为了使质谱技术发挥作用，分子必须被离子化并进入气态。在基质辅助激光解吸电离（MALDI）中，样品被嵌入一种基质中，该基质通常是一种含有芳香环和共轭双键的有机化合物。当激光脉冲照射到此混合物时，基质吸收了大部分能量，迅速升温，并从表面解吸或释放出来。被激发的基质将部分能量传递给生物分子，使其解吸并随后离子化。MALDI 通常与飞行时间（TOF）质谱分析器联用。电场为离子提供动能，使其进入一个无电场区域，称为漂移管。离子在漂移管中运动的速度与其质荷比相关，因此较重的粒子在仪器中移动得更慢。漂移管末端的检测器测量每个离子的飞行时间。结合已知的漂移管长度和施加的电场强度，即可推算出每个离子的质荷比。这种信号强度与质荷比的关系图称为质谱图，可与已收集的谱图数据库进行比对。若未找到匹配项，则可通过串联质谱等进一步技术来鉴定分子。欲了解更多信息，请参见本合集中关于该主题的视频。在讨论了基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）的基本原理之后，让我们来看一下在实验室中的操作过程。在开始实验之前，必须考虑用于解吸样品的基质选择。该基质需能够吸收激光能量、在真空条件下保持稳定、不与目标分子发生反应，并具备良好的解吸能力。根据样品的不同，所选用的基质也有所差异。对于大分子蛋白质，CHCA与DHB的组合相较于单独使用任一种基质，能够实现更佳的峰分离效果，即更高的分辨率。制备样品的方法有多种。我们将展示一种被称为“双层”或“三明治”法的技术。首先，使用超纯试剂清洗 MALDI 板，因为质谱分析对污染非常敏感。随后用惰性气体气流将样品板吹干。接下来，制备饱和基质溶液，通常使用有机溶剂。将该溶液涂抹到MALDI靶板上并干燥。随后配制第二种含有三氟乙酸（TFA）的饱和基质溶液。TFA有助于使离子进入气相。接下来，将样品溶液加至干燥的基质点上方。再将含有三氟乙酸（TFA）的基质溶液加至样品上，从而完成基质“三明治”结构。可通过低倍显微镜观察以验证样品点的均匀性。点样校准标准品，该标准品是含有已知质量范围较广的混合物，用于关联飞行时间与质荷比（m/z）。最后，仅点样基质作为阴性对照。为分析斑点，将目标板放入仪器中。确保无任何碎片存在，以形成严密的真空。在软件中选择标准品、阴性对照以及目标样本。使用正确的标识对斑点进行标记。可以通过调节离子源和透镜电压来提高分析性能。具体设置取决于仪器和样品的特性。将焦点对准标准样品点，并使用软件对仪器进行校准。接下来，从每个样品点采集谱图。在样品点上尝试几个不同的位置，以最大限度地提高所采集数据的质量。完成后，可将MALDI靶板收集起来，经清洗后重复使用。在回顾了一种实验流程之后，让我们来看看基质辅助激光解吸电离（MALDI）的一些应用方式，以及另一种不同的电离技术。除了生物分子外，基质辅助激光解吸电离（MALDI）还可用于分析活细胞。巨噬细胞是一类免疫细胞，其形态会根据微环境的不同而转变为多种不同表型。在将细胞暴露于各种信号分子或细胞因子后，可直接将其加入样品板中进行分析。所获得的MALDI质谱图可作为独特的“指纹”特征，具体图谱特征取决于所使用的细胞因子。像哺乳动物皮脂分泌物这样的复杂生物样品在进行MALDI分析之前，需要经过纯化步骤。薄层色谱法就是一种基于组分极性的技术。从TLC板上收集化合物，经过纯化后转移至MALDI基质中。所得质谱图可验证从哺乳动物皮脂分泌物中分离出的生物分子的身份和纯度。另一种常见的生物分子离子源是电喷雾电离（ESI）。在该方法中，样品被直接注入仪器，施加高电压后形成带电液滴的气溶胶。随着液滴中溶剂的蒸发，电荷转移至样品分子，直至其完全转变为气相。ESI 不需要点样步骤，样品可直接注入仪器。然而，ESI 对缓冲液组分及其他污染物更为敏感，因此相比之下，MALDI 具有更强的抗干扰能力。您刚刚观看了 JoVE 关于基质辅助激光解吸电离质谱（MALDI 质谱）的视频。该视频介绍了该仪器背后的理论原理，概述了一般操作流程，并探讨了该技术的一些应用。感谢观看！

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MALDI TOF 质谱

how maldi-tof reads biomolecules

MALDI-TOF mass spectrometry reads biomolecules by using a laser, a matrix, and a time-of-flight analyzer. MALDI, or matrix-assisted laser desorption ionization, helps fragile molecules keep their structure while they are moved into the mass analyzer. The analyzer then separates compounds based on size and charge.

In MALDI, the sample is mixed into a matrix, usually an organic compound with aromatic and conjugated double bonds. A laser pulse strikes the spot, and the matrix absorbs most of the energy. The matrix heats up, is desorbed from the surface, and transfers energy to the biomolecules so they ionize. MALDI is commonly paired with TOF, or time of flight, mass analysis.

The TOF analyzer uses an electric field to give ions kinetic energy and send them through a field-free drift tube. Ions move at different speeds based on their mass-to-charge ratio, so heavier ions travel more slowly. A detector measures each ion’s flight time. The instrument uses the tube length and field strength to calculate the mass-to-charge ratio and create a mass spectrum.

Before analysis, the matrix must be chosen carefully. It must absorb laser energy, stay stable in a vacuum, avoid reacting with the target molecules, and still desorb well. Different samples work better with different matrices. For a large protein, a combination of CHCA and DHB can give better peak resolution than either matrix alone.

Sample preparation can use the double-layer, or sandwich, method. First, the MALDI plate is cleaned with ultra-pure reagents and dried with inert gas, because mass spectrometry is sensitive to contamination. A saturated matrix solution is spotted and dried, then a second matrix solution containing trifluoroacetic acid, or TFA, is added with the sample in between. TFA helps ions enter the gaseous phase. The spot can be checked under a low-powered microscope.

A calibration standard is also plated. This standard contains a wide range of known masses and is used to match flight time to m/z. A matrix-only spot serves as a negative control. After the plate is loaded into the instrument, the software is used to label the spots, calibrate with the standard, and collect spectra from the samples. The ion source and lens voltages can be adjusted to improve performance, and several spots on each sample can be measured to improve data quality. The MALDI plate can be cleaned and reused after the run.

MALDI is also useful for whole-cell analysis and complex biological samples. Macrophages, which are immune cells, can be exposed to different cytokines and then analyzed directly on the plate. Their MALDI spectra can act as fingerprints for each cytokine condition. For mammalian sebaceous secretions, thin layer chromatography can first separate the components by polarity before the purified compounds are transferred to a MALDI matrix.

Another biomolecule ion source is electrospray ionization, or ESI. In ESI, the sample is injected directly into the instrument and a high voltage creates charged droplets. As the solvent evaporates, the charge moves to the sample molecules until they become gaseous. ESI does not need the spotting step, but it is more sensitive to buffer components and other contaminants, so MALDI is often the more robust choice.

How MALDI-TOF Reads Biomolecules

dialysis: diffusion based separation

Dialysis for Buffer Exchange in Biochemistry

Dialysis is a common biochemistry technique for buffer exchange and desalting. It separates molecules by diffusion through a semipermeable membrane, which lets small molecules pass while holding larger biomolecules inside the sample. The membrane is the key part of the setup. Its pores create a molecular weight cutoff, so a membrane such as a 10 kDa membrane usually keeps molecules larger than 10 kilodaltons inside. This cutoff is not exact, because membranes have a range of pore sizes.

enzyme assays and kinetics

Measuring Enzyme Reaction Rates

Enzyme reaction rates can be measured with assays that track how substrate or product levels change over time. Enzymes are proteins, or sometimes RNAs, that speed up chemical reactions by lowering the activation energy needed to start them. They act on a specific substrate and help form a product that supports life processes. Enzymatic reactions are often described in three steps. First, the substrate binds to the enzyme active site and forms an enzyme-substrate complex. That complex can fall...

maldi-tof mass spectrometry

MALDI-TOF mass spectrometry reads biomolecules by using a laser, a matrix, and a time-of-flight analyzer. MALDI, or matrix-assisted laser desorption ionization, helps fragile molecules keep their structure while they are moved into the mass analyzer. The analyzer then separates compounds based on size and charge. In MALDI, the sample is mixed into a matrix, usually an organic compound with aromatic and conjugated double bonds. A laser pulse strikes the spot, and the matrix absorbs most of the...

tandem mass spectrometry

Tandem Mass Spectrometry for Biomolecule Analysis

Tandem mass spectrometry is used to isolate a biomolecule and break it into smaller pieces so its makeup can be studied. Because biomolecules often have large, complex structures, it can be hard to identify their molecular composition and sequence from a single measurement. By linking mass spectrometers in series, the technique first selects one ion and then analyzes the fragments it produces. The process starts with an ion source that converts the sample into ions. A mass analyzer then...

protein crystallization

Protein Crystals for Structure Analysis

Protein crystals help scientists study protein structure and function. A crystal is a solid lattice made from purified protein molecules. These crystals are useful in structural biology because they reveal details that methods like mass spectrometry and SDS-PAGE cannot show on their own. Protein crystallization is paired with recombinant protein expression and x-ray diffraction to support this work. The process starts with a large amount of very pure protein. Researchers often make that...

chromatography-based biomolecule purification methods

chromatography-based-biomolecule-purification-methods

Protein Purification with SEC and IMAC

Protein purification with size-exclusion chromatography and affinity chromatography helps isolate biomolecules from complex mixtures. These methods are common in biochemistry because purified samples are needed before a biomolecule’s properties and activity can be studied. The video focuses on the principles behind size-exclusion chromatography, affinity chromatography, and immobilized metal affinity chromatography, or IMAC. Size-exclusion chromatography, or SEC, separates molecules by size. A...

two-dimensional gel electrophoresis

Protein Mapping with 2D Gel Electrophoresis

Protein mapping with 2D gel electrophoresis separates complex protein mixtures across two steps. The method combines isoelectric focusing, or IEF, with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or SDS-PAGE. Together, these methods can resolve thousands of biomolecules from a single sample by their isoelectric point and molecular weight. The first dimension is IEF. Each protein has an isoelectric point, or pI, which is the pH where its net charge is zero. Proteins are loaded...

metabolic labeling

Tracking Cell Chemistry with Metabolic Labels

Metabolic labeling tracks cell chemistry by using chemical analogs that cells take up and build into biomolecules. These labels help scientists follow biochemical changes and modifications inside cells. The labeled products can then be studied with tools such as SDS-PAGE and NMR to learn more about metabolic pathways. Several labeling strategies are shown here. Isotopic labeling uses analogs that match the natural molecule but contain uncommon isotopes, such as carbon-13 and nitrogen-15 in an...

electrophoretic mobility shift assay (emsa)

electrophoretic-mobility-shift-assay-emsa

Detecting Protein-DNA Binding by EMSA

Electrophoretic mobility shift assay, or EMSA, is a biochemical method used to detect binding between proteins and nucleic acids. It is also called a gel shift assay. The test compares how a labeled nucleic acid moves through a gel before and after it binds a protein. EMSA is used to see whether a specific protein binds to a specific nucleic acid. First, the nucleic acid is labeled to make a probe. The transcript describes radioactive phosphorus-32 as a common label. The probe is then mixed...

photometric protein determination

Measuring Protein Concentration with Absorbance

Measuring protein concentration with absorbance is a key step in many biochemical assays. Photometric methods use the fact that samples with more light-absorbing material transmit less light. Because concentration and absorption are directly related, this makes it possible to measure an unknown sample. The core idea comes from the Beer-Lambert Law. This law states that the concentration of a light-absorbing species is proportional to its absorbance. The video also introduces the Bradford assay...

density gradient ultracentrifugation

Sucrose Gradient Separation in an Ultracentrifuge

Sucrose gradient separation in an ultracentrifuge is a lab method for isolating cell parts and biomolecules. It uses differences in density to make particles sink or rise in a liquid. A high-speed ultracentrifuge speeds up this process so components can be separated without destroying them. The basic idea starts with a suspension, which is particles mixed in a liquid solvent. Particles that are denser than the solvent sediment, while less dense particles float. A rotor inside the...

co-immunoprecipitation and pull-down assays

co-immunoprecipitation-and-pull-down-assays

Protein Interaction Capture Methods in Cells

Co-immunoprecipitation and pull-down assays are laboratory methods used to capture stable protein-protein interactions. Protein-protein interactions help control many biological functions, but many of them have not yet been identified. These assays are related to immunoprecipitation, which isolates a target protein from a mixed sample using an antibody. In co-immunoprecipitation, or CoIP, an antibody binds the target protein, and that protein is already attached to another protein that the...

reconstitution of membrane proteins

Membrane Proteins in Liposome Models

Membrane proteins can be moved into liposome models so their function can be studied outside a cell. Reconstitution means restoring an isolated biomolecule to a working form. For membrane proteins, that usually means placing a purified protein into an artificial lipid membrane. Cell membranes are made mainly of phospholipids and membrane proteins. The phospholipids form a bilayer with hydrophilic phosphate heads facing water and hydrophobic fatty acid tails facing inward. Some membrane...

f&#246;rster resonance energy transfer (fret)

FRET as a Molecular Ruler in Cells

Föster resonance energy transfer, or FRET, is a way to study close-range biochemical interactions using light-emitting molecules. A donor fluorophore can pass energy to an acceptor fluorophore when their emission and absorption spectra overlap. This transfer happens only when the pair is very close together, usually within 10 nm. Because FRET depends on distance, it is often called a molecular or spectroscopic ruler. The strength of the signal is measured as FRET efficiency, which describes...

surface plasmon resonance (spr)

SPR Biosensors for Tracking Binding Kinetics

Surface plasmon resonance, or SPR, is a way to track biomolecular binding on a label-free biosensor. It is used to measure molecular affinity, kinetics, specificity, and concentration. The method works with a thin metal layer on a prism, where changes in reflected light reveal interactions in real time. SPR sensors use a thin layer of a noble metal on the face of a prism. Light is reflected from the prism-metal interface into a photodetector. At one specific angle, called the surface plasmon...

biochemistry

本系列介绍了常用的纯化方法, 如亲和层析, 以及分析方法, 如 MALDI。此外, 视频展示了评估生物相互作用和功能的方法, 如 co-immunoprecipitation 和代谢标记。

Learn how MALDI-TOF mass spectrometry uses a laser, matrix, and time-of-flight analyzer to identify biomolecules, cells, and complex samples.

How MALDI-TOF Reads Biomolecules | JoVE K12

Life Science

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-6.

Overview

Principles of MALDI-TOF Mass Spectrometry

Plate, Matrix, and Sample Preparation

Running the Mass Spectrometer

Applications

Summary

Travelling Waves

A wave is a disturbance that propagates from its source, repeating itself periodically, and is typically associated with simple harmonic motion. ...

Wave Parameters

The simplest mechanical waves are associated with simple harmonic motion and repeat themselves for several cycles. These simple harmonic waves can be ...

Equations of Wave Motion

Mathematically, the motion of a wave can be studied using a wavefunction. Consider a string oscillating up and down in simple harmonic motion, having a ...

Graphing the Wave Function

Consider the wave equation for a sinusoidal wave moving in the positive x-direction. The wave equation is a function of both position and time. From the ...

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Velocity and Acceleration of a Wave

A wave propagates through a medium with a constant speed, known as a wave velocity. It is different from the speed of the particles of the medium, which ...

Speed of a Transverse Wave

The speed of a wave depends on the characteristics of the medium. For example, in the case of a guitar, the strings vibrate to produce the sound. The ...

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problem-solving-tuning-of-a-guitar-string

Problem-Solving: Tuning of a Guitar String

In the case of stringed instruments like the guitar, the elastic property that determines the speed of the sound produced is its linear mass density or ...

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Kinetic and Potential Energy of a Wave

All forms of waves carry energy; this is directly visualized in nature. For instance, the waves of earthquakes are so intense that they can shake huge ...

Energy and Power of a Wave

The total energy associated with a wavelength is the sum of the potential energy and the kinetic energy. The average rate of energy transfer associated ...

Interference and Superposition of Waves

When two waves of the same nature occur in the same region simultaneously, they result in interference. Interference of waves implies that the net effect ...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Propagation of Waves

When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second ...

Standing Waves

Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a ...

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Modes of Standing Waves - I

A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. ...

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Modes of Standing Waves: II

The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions ...

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Sound Waves

Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium&#39;s ...

Sound as Pressure Waves

Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As ...

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Perception of Sound Waves

The human ear is not equally sensitive to all frequencies in the audible range. It may perceive sound waves with the same pressure but different ...

Speed of Sound in Solids and Liquids

Most solids and liquids are incompressible&#8212;their densities remain constant throughout. In the presence of an external force, the molecules tend to ...

Speed of Sound in Gases

The speed of sound in a gaseous medium depends on various factors. Since gases constitute molecules that are free to move, they are highly compressible. ...

Shock Waves

While deriving the Doppler formula for the observed frequency of a sound wave, it is assumed that the speed of sound in the medium is greater than the ...

Echo

The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More ...

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Use mathematical representations to support a claim regarding relationships among the period, frequency, wavelength, and speed of waves traveling and transferring energy (amplitude, frequency) in various media.

HS-PS4-1.

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

Evaluate questions about the advantages of using a digital transmission and storage of information.

HS-PS4-2.

concept-of-resonance-and-its-characteristics

Concept of Resonance and its Characteristics

If a driven oscillator needs to resonate at a specific frequency, then very light damping is required. An example of light damping includes playing piano ...

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Sound Waves: Resonance

Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical ...

Sound Waves: Interference

Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure ...

Interference: Path Lengths

Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two ...

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The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the ...

The Quantum-Mechanical Model of an Atom

Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of ...

Quantum Numbers

It is said that the energy of an electron in an atom is quantized; that is, it can be equal only to certain specific values and can jump from one energy ...

Interference and Diffraction

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Interference and diffraction ...

Photoelectric Effect

Source: Yong P. Chen, PhD, Department of Physics &#38;&#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Photoelectric effect ...

Reflection and Refraction

Source: Derek Wilson,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of California, Irvine, CA
...

Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model (quantum theory), and that for some situations one model is more useful than the other.

HS-PS4-3.

Electric Charge in a Magnetic Field

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment duplicates J.J. Thomson's famous experiment at the end of ...

Electromagnetic Fields

Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...

Electromagnetic Waves

James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his ...

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as ...

Plane Electromagnetic Waves I

The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of ...

Plane Electromagnetic Waves II

Consider a plane wavefront traveling in position x-direction with a constant speed. This wavefront can be utilized to obtain the relationship between ...

propagation-speed-of-electromagnetic-waves

Propagation Speed of Electromagnetic Waves

Electromagnetic waves are consistent with Ampere&#39;s law. Assuming there is no conduction current Ampere&#39;s law is given as:


Consider a plane ...

Electromagnetic Waves in Matter

Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, ...

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun&#39;s ...

Intensity Of Electromagnetic Waves

The energy transport per unit area per unit time, or the Poynting vector, gives the energy flux of an electromagnetic wave at any specific time. For a ...

Momentum And Radiation Pressure

An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because ...

Cardiac Magnetic Resonance Imaging

Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high ...

an-introduction-to-drosophila-melanogaster

An Introduction to Drosophila melanogaster

Drosophila melanogaster, also known as the fruit fly, is a powerful model organism widely used in biological research that has made significant ...

an-introduction-to-the-zebrafish-danio-rerio

An Introduction to the Zebrafish: Danio rerio

Zebrafish (Danio rerio) are small freshwater fish that are used as model organisms for biomedical research. The many strengths of these fish include their ...

Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.

HS-PS4-4.

How MALDI-TOF Reads Biomolecules

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