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Particle Mass Analyser
A Particle mass analyser (PMA) is an instrument for classifying aerosol particles according to their mass-to-charge ratio using opposing electrical and centrifugal forces. This allows the classifier to select particles of a specified mass-to-charge ratio independent of particle shape. It one of the three types of monodisperse aerosol classifier, the others being the differential mobility analyser (DMA, for electrical mobility size), and the aerodynamic aerosol classifier (AAC, for relaxation time, or aerodynamic diameter An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be generated from natural or human causes. The term ''aerosol'' commonly refers to the mixture of particulates in air, and not to the par ...). The corresponding three quantities are related by the expression ''τ'' = ''mB'', where ''τ'' is relaxation time, ''m'' is mass and ''B'' is mobility. Further work improved the technique by engineering the cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from Spray nozzle, atomizers, smoke, dust, Pesticide, sprayed pesticides, and medical treatments for respiratory illnesses. Several types of atmospheric aerosol have a significant effect on Earth's climate: volcanic, desert dust, sea-salt, that originating from biogenic sources and human-made. Volcanic aerosol forms in the stratosphere after an eruption as droplets of sulfuric acid that can prevail for up to two years, and reflect sunlight, lowering tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Field
An electric field (sometimes called E-field) is a field (physics), physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) describes their capacity to exert attractive or repulsive forces on another charged object. Charged particles exert attractive forces on each other when the sign of their charges are opposite, one being positive while the other is negative, and repel each other when the signs of the charges are the same. Because these forces are exerted mutually, two charges must be present for the forces to take place. These forces are described by Coulomb's law, which says that the greater the magnitude of the charges, the greater the force, and the greater the distance between them, the weaker the force. Informally, the greater the charge of an object, the stronger its electric field. Similarly, an electric field is stronger nearer charged objects and weaker f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrifugal Force
Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axis of rotation of the frame. The magnitude of the centrifugal force ''F'' on an object of mass ''m'' at the perpendicular distance ''ρ'' from the axis of a rotating frame of reference with angular velocity is F = m\omega^2 \rho. This fictitious force is often applied to rotating devices, such as centrifuges, centrifugal pumps, centrifugal governors, and centrifugal clutches, and in centrifugal railways, planetary orbits and banked curves, when they are analyzed in a non–inertial reference frame such as a rotating coordinate system. The term has sometimes also been used for the '' reactive centrifugal force'', a real frame-independent Newtonian force that exists as a reaction to a centripetal force in some scenarios. History F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Mobility Spectrometry
Ion mobility spectrometry (IMS) It is a method of conducting analytical research that separates and identifies ionized molecules present in the gas phase based on the mobility of the molecules in a carrier buffer gas. Even though it is used extensively for military or security objectives, such as detecting drugs and explosives, the technology also has many applications in laboratory analysis, including studying small and big biomolecules. IMS instruments are extremely sensitive stand-alone devices, but are often coupled with mass spectrometry, gas chromatography or high-performance liquid chromatography in order to achieve a multi-dimensional separation. They come in various sizes, ranging from a few millimetres to several metres depending on the specific application, and are capable of operating under a broad range of conditions. IMS instruments such as microscale high-field asymmetric-waveform ion-mobility spectrometry, high-field asymmetric-waveform ion mobility spectrometry ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Mobility
Electrical mobility is the ability of charged particles (such as electrons or protons) to move through a medium in response to an electric field that is pulling them. The separation of ions according to their mobility in gas phase is called ion mobility spectrometry, in liquid phase it is called electrophoresis. Theory When a charged particle in a gas or liquid is acted upon by a uniform electric field, it will be accelerated until it reaches a constant drift velocity according to the formula v_\text = \mu E, where * v_\text is the drift velocity (SI units: m/s), * E is the magnitude of the applied electric field (V/m), * \mu is the mobility (m2/(V·s)). In other words, the electrical mobility of the particle is defined as the ratio of the drift velocity to the magnitude of the electric field: \mu = \frac. For example, the mobility of the sodium ion (Na+) in water at 25 °C is . This means that a sodium ion in an electric field of 1 V/m would have an average drift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamic Aerosol Classifier
An aerodynamic aerosol classifier (AAC) is an embodiment of a measurement technique for classifying aerosol particles according to their aerodynamic diameters. The technique allows online size classification of particles without requiring them to be electrically charged, and advantageously allows selection of particles within a narrow range of aerodynamic diameters. This is by contrast to an impactor or virtual impactor, which allow only particles smaller than, or larger than, a certain cut-point, respectively. A practically implementable AAC can classify particles from the nanometre range to a few microns in size. This removes many of the difficulties associated with multiple charging artifacts, such as may be encountered when classifying particles by size according to electrical mobility (such as the differential mobility analyser or DMA). The selection of particles by aerodynamic diameter also lends itself to respiratory and inhalation applications as this metric directly affec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from Spray nozzle, atomizers, smoke, dust, Pesticide, sprayed pesticides, and medical treatments for respiratory illnesses. Several types of atmospheric aerosol have a significant effect on Earth's climate: volcanic, desert dust, sea-salt, that originating from biogenic sources and human-made. Volcanic aerosol forms in the stratosphere after an eruption as droplets of sulfuric acid that can prevail for up to two years, and reflect sunlight, lowering tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Instruments
Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related areas of metrology, automation, and control theory. The term has its origins in the art and science of scientific instrument-making. Instrumentation can refer to devices as simple as direct-reading thermometers, or as complex as multi-sensor components of industrial control systems. Instruments can be found in laboratories, refineries, factories and vehicles, as well as in everyday household use (e.g., smoke detectors and thermostats). Measurement parameters Instrumentation is used to measure many parameters (physical values), including: *Pressure, either differential or static * Flow *Temperature * Levels of liquids, etc. *Moisture or humidity *Density *Viscosity * ionising radiation *Frequency * Current *Voltage *Inductance *C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Instruments
A scientific instrument is a device or tool used for scientific purposes, including the study of both natural phenomena and theoretical research. History Historically, the definition of a scientific instrument has varied, based on usage, laws, and historical time period. Before the mid-nineteenth century such tools were referred to as "natural philosophical" or "philosophical" apparatus and instruments, and older tools from antiquity to the Middle Ages (such as the astrolabe and pendulum clock) defy a more modern definition of "a tool developed to investigate nature qualitatively or quantitatively." Scientific instruments were made by instrument makers living near a center of learning or research, such as a university or research laboratory. Instrument makers designed, constructed, and refined instruments for purposes, but if demand was sufficient, an instrument would go into production as a commercial product. In a description of the use of the eudiometer by Jan Ingenhousz to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Techniques
A scientific technique is any systematic way of obtaining information about a scientific nature or to obtain a desired material or product. Scientific techniques can be divided in many different groups, e.g.: # Preparative techniques ## Synthesis techniques, e.g. the use of Grignard reagents in organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ... ## Growth techniques, e.g. crystal growth or cell cultures in biology ## Purification techniques e.g. List of purification methods in chemistry, those in chemistry # Measurement techniques ## Analysis techniques, e.g. ones that reveal atomic or molecular composition. ## Characterization techniques, e.g. ones that measure a certain property of a material. ## Imaging techniques, e.g. microscopy In some cases these methods h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
