Coulter Principle
Coulter Principle - Related Videos
08:37
Le Châtelier's Principle
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2023
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...
04:08
The Uncertainty Principle
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2020
Werner Heisenberg considered the limits of how accurately one can measure properties of an electron or other microscopic particles. He determined that there is a fundamental limit to how accurately one can measure both a particle’s position and its momentum simultaneously. The more accurate the measurement of the momentum of a particle is known, the less accurate the position at that time is known and vice versa. This is what is now called the Heisenberg uncertainty principle. He mathematically...
03:06
The Pauli Exclusion Principle
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2020
The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that contains three pieces of information: The number of the principal quantum shell, n, The letter that designates the orbital type (the subshell, l), and A superscript number that designates the number of electrons in that particular subshell. For example, the notation 2p4 indicates four electrons in a p subshell (l = 1) with a principal...
03:02
The Aufbau Principle and Hund's Rule
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2020
To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and continuing across the periods of the periodic table, we add one proton at a time to the nucleus and one electron to the proper subshell until we have described the electron configurations of all the elements. This procedure is called the aufbau principle, from the German word aufbau (“to build up”). Each added electron occupies the subshell of...
10:29
Principles of Rodent Surgery for the New Surgeon
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Cited by 56 •
2011
Before attempting surgery, a new surgeon should have training in basic surgical techniques and concepts. This article will present basic surgical considerations with an emphasis on rodents.
FAQs
Each particle passage produces an electrical pulse, so the total number of pulses corresponds to the number of particles detected. Pulse amplitude supplies a separate measurement because it reflects the volume of the particle displacing electrolyte. Together, these signals provide both concentration-related counts and information about the size distribution within a sample.
The aperture creates the restricted path through which suspended particles pass, while the electrolyte provides the conductive fluid needed for electrical measurement. Electrodes positioned across the opening detect the transient resistance change caused by fluid displacement. Without this coordinated arrangement, particle passage could not be converted into the electrical pulses used for analysis.
A size distribution shows how particle volumes are represented across a sample rather than reporting only its total concentration. Changes in the distribution can therefore indicate shifts in the cell population, while pulse counts reveal the number of detected particles. This combination supports quantitative assessment of sample composition and biological changes.
A cell-containing suspension is placed in an electrolyte-filled measurement system, and particles pass individually through its small aperture between electrodes. The instrument records the resulting resistance pulses, then uses pulse number and amplitude to quantify particle count and volume-related size information. The resulting measurements can be summarized as concentration and size-distribution data.
In automated hematology analyzers, electrical pulse measurements provide rapid quantitative information about cells in a biological sample. Pulse counts support cell enumeration, while amplitudes contribute volume-related sizing. This combination helps the instruments characterize cell populations efficiently, making the principle useful where repeated, standardized measurements are needed in hematology workflows.
Cell-based researchers can use the resulting concentration and size data to monitor growth, examine disease-related changes, and evaluate responses to experimental treatments. The same measurements also support sample-quality assessment by revealing quantitative features of the cell population. These applications make the method relevant for both experimental interpretation and quality-control decisions.