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相关概念视频

Mass Spectrum01:23

Mass Spectrum

A mass spectrum is the graphical representation of the relative abundance of the charged fragments in an analyte plotted against their mass-to-charge ratio (m/z). The plot's x-axis represents the ratio of the mass of the charged fragment to the number of charges it carries. The y axis of the plot represents the relative abundance of each charged species. The relative abundance is calculated from the signal intensity of each charged species recorded at the detector. The most intense signal (the...
Detection of Black Holes01:10

Detection of Black Holes

Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Mass Spectrometry of Amines01:15

Mass Spectrometry of Amines

In mass spectroscopy, amines undergo fragmentation to give parent ions with odd molecule weights. This observed mass spectrum follows the nitrogen rule; a molecule with an odd number of nitrogen atoms produces a molecular ion with an odd molecular weight. Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit strong molecular ion peaks, but acyclic aliphatic amines show...
Mass Spectrometers01:16

Mass Spectrometers

This lesson details the instrumentation of a mass spectrometer—a physical instrument to perform mass spectrometry on analyte molecules and record the characteristic mass spectra. This is achieved via three chief functions:
MALDI-TOF Mass Spectrometry01:19

MALDI-TOF Mass Spectrometry

Mass spectrometry is a powerful characterization technique that can identify and separate a wide variety of compounds ranging from chemical to biological entities, based on their mass-to-charge ratio (m/z). The instruments that allow this detection, known as mass spectrometers, have three components: an ion source, a mass analyzer, and a detector. These spectrometers differ based on the nature of their ion source and analyzers.Matrix-assisted laser desorption ionization (MALDI) is a commonly...
Tandem Mass Spectrometry01:21

Tandem Mass Spectrometry

Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and reduce chemical noise during analyte detection. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called...

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相关实验视频

Updated: Jun 29, 2026

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue
10:17

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Published on: June 18, 2014

在莫丹地下实验室使用NEWS-G使用甲目标对光暗物质进行搜索.

M M Arora1, L Balogh1, C Beaufort2

  • 1Queen's University, Department of Mechanical and Materials Engineering, Kingston, Ontario K7L 3N6, Canada.

Physical review letters
|April 25, 2025
PubMed
概括

NEWS-G实验使用球形比例计数器搜索轻暗物质. 新的结果提供了对暗物质-质子相互作用在亚-GeV质量范围内改善的约束.

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Construction of Cell-based Neurotransmitter Fluorescent Engineered Reporters (CNiFERs) for Optical Detection of Neurotransmitters In Vivo
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Construction of Cell-based Neurotransmitter Fluorescent Engineered Reporters (CNiFERs) for Optical Detection of Neurotransmitters In Vivo

Published on: May 12, 2016

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis
14:53

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

Published on: February 3, 2018

相关实验视频

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Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue
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Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Published on: June 18, 2014

Construction of Cell-based Neurotransmitter Fluorescent Engineered Reporters (CNiFERs) for Optical Detection of Neurotransmitters In Vivo
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Construction of Cell-based Neurotransmitter Fluorescent Engineered Reporters (CNiFERs) for Optical Detection of Neurotransmitters In Vivo

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In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis
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In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

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科学领域:

  • 粒子物理学 粒子物理学
  • 宇宙学的宇宙学是什么?
  • 天体物理学 天体物理学

背景情况:

  • 暗物质的性质仍然是物理学中最重要的未解决的问题之一.
  • 直接检测实验的目的是观察暗物质粒子与普通物质相互作用.
  • 光暗物质的候选物质在目前的实验灵敏度下特别难以检测.

研究的目的:

  • 使用NEWS-G (用球状中性气体进行新实验) 探测器搜索轻暗物质候选物质.
  • 为了限制暗物质模型的参数空间,特别关注与质子的自旋依赖相互作用.
  • 报告最近使用大型球形比例计数器进行的10天物理运行的新结果.

主要方法:

  • 使用了一个直径为135厘米的球形比例计数器,填充了114克甲作为目标气体.
  • 在莫丹地下实验室 (LSM) 进行了为期10天的物理数据采集运行.
  • 分析了探测器对潜在暗物质信号的反应,重点关注低能核反弹.

主要成果:

  • 获得了对暗物质与质子的自旋依赖合的灵敏度.
  • 对0.17至1.2GeV/c2.2质量范围内的浅暗物质提出了新的排除极限.
  • 对于0.76 GeV/c2.2的暗物质质量,建立了90%的置信度水平的截面上限30.9 pb.

结论:

  • NEWS-G实验成功地限制了光暗物质模型的参数空间.
  • 结果表明,球形比例计数器在未来的直接检测实验中具有潜力.
  • 预计进一步的分析和更长的运行将提高对暗物质相互作用的灵敏度.