In general, a sample is a limited quantity of something which is intended to be similar to and represent a larger amount of that thing(s). The things could be countable objects such as individual items available as units for sale, or an uncountable material. Even though the word "sample" implies a smaller quantity taken from a larger amount, sometimes full biological or mineralogical specimens are called samples if they are taken for analysis, testing, or investigation like other samples. They are also considered samples in the sense that even whole specimens are "samples" of the full population of many individual organisms. The act of obtaining a sample is called "sampling" and can be performed manually by a person or by automatic process. Samples of material can be taken or provided for testing, analysis, investigation, quality control, demonstration, or trial use. Sometimes, sampling may be performed continuously.
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👉 Sample (material) in the context of Differential interference contrast microscopy
Differential interference contrast (DIC) microscopy, also called Nomarski interference contrast (NIC) or Nomarski microscopy, is an optical microscopy technique used to enhance the contrast in unstained, transparent samples. DIC works on the principle of interferometry to gain information about the optical path length of the sample, to see otherwise invisible features. A relatively complex optical system produces an image with the object appearing black to white on a grey background. This image is similar to that obtained by phase-contrast microscopy, but without the bright diffraction halo. The technique was invented by Francis Hughes Smith. The "Smith DIK" was produced by Ernst Leitz Wetzlar in Germany and was difficult to manufacture. DIC was then developed further by Polish physicist Georges Nomarski in 1952.
DIC works by separating a polarized light source into two orthogonally polarized mutually coherent parts which are spatially displaced (sheared) at the sample plane, and recombined before observation. The interference of the two parts at recombination is sensitive to their optical path difference (i.e. the product of refractive index and geometric path length). Adding an adjustable offset phase determining the interference at zero optical path difference in the sample, the contrast is proportional to the path length gradient along the shear direction, giving the appearance of a three-dimensional physical relief corresponding to the variation of optical density of the sample, emphasising lines and edges though not providing a topographically accurate image.
- ⭐ Core Definition: Sample (material)
- 👉 Sample (material) in the context of Differential interference contrast microscopy
- Sample (material) in the context of Chemical purity
- Sample (material) in the context of Laboratory specimen
- Sample (material) in the context of Rosette sampler
- Sample (material) in the context of Energy-dispersive X-ray spectroscopy
- Sample (material) in the context of Product sample
Sample (material) in the context of Chemical purity
In chemistry, chemical purity is the measurement of the amount of impurities found in a sample. Several grades of purity are used by the scientific, pharmaceutical, and industrial communities. Some of the commonly used grades of purity include:
- ACS grade is the highest level of purity, and meets the standards set by the American Chemical Society (ACS). The official descriptions of the ACS levels of purity is documented in the Reagent Chemicals publication, issued by the ACS. It is suitable for food and laboratory uses.
- Reagent grade is almost as stringent as the ACS grade.
- USP grade meets the purity levels set by the United States Pharmacopeia (USP). USP grade is equivalent to the ACS grade for many drugs.
- NF grade is a purity grade set by the National Formulary (NF). NF grade is equivalent to the ACS grade for many drugs.
- British Pharmacopoeia: Meets or exceeds requirements set by the British Pharmacopoeia (BP). Can be used for food, drug, and medical purposes, and also for most laboratory purposes.
- Japanese Pharmacopeia: Meets or exceeds requirements set by the Japanese Pharmacopoeia (JP). Can be used for food, drug, and medical purposes, and also for most laboratory purposes.
- Laboratory grade is suitable for use in educational settings, but is not acceptable for food or drug use.
- Purified grade is not precisely defined, and it is not suitable for drug or food usage.
- Technical grade is suitable for industrial applications, but is not acceptable for food or drug use.
Sample (material) in the context of Laboratory specimen
A laboratory specimen is sometimes a biological specimen of a medical patient's tissue, fluids, or other samples used for laboratory analysis to assist in differential diagnosis or staging of a disease process. These specimens are often the most reliable method of diagnosis, depending on the ailment. For example, breast cancer biopsies, performed on laboratory specimens of breast tissue, yield just a 2% rate of incorrect diagnosis. Laboratory specimens may also include feces.
View the full Wikipedia page for Laboratory specimenSample (material) in the context of Rosette sampler
A rosette sampler (also known as a CTD-rosette or carousel) is a device used for water sampling in deep water. Rosette samplers are used in the ocean and large inland water bodies such as the North American Great Lakes in order to investigate quality. Rosette samplers are a key piece of equipment in oceanography and have been used to collect information over many years in repeat hydrographic surveys.
View the full Wikipedia page for Rosette samplerSample (material) in the context of Energy-dispersive X-ray spectroscopy
Energy-dispersive X-ray spectroscopy (EDS, EDX, EDXS or XEDS), sometimes called energy dispersive X-ray analysis (EDXA or EDAX) or energy dispersive X-ray microanalysis (EDXMA), is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing a unique set of peaks on its electromagnetic emission spectrum (which is the main principle of spectroscopy). The peak positions are predicted by the Moseley's law with accuracy much better than experimental resolution of a typical EDX instrument.
To stimulate the emission of characteristic X-rays from a specimen a beam of electrons or X-ray is focused into the sample being studied. At rest, an atom within the sample contains ground state (or unexcited) electrons in discrete energy levels or electron shells bound to the nucleus. The incident beam may excite an electron in an inner shell, ejecting it from the shell while creating an electron hole where the electron was. An electron from an outer, higher-energy shell then fills the hole, and the difference in energy between the higher-energy shell and the lower energy shell may be released in the form of an X-ray. The number and energy of the X-rays emitted from a specimen can be measured by an energy-dispersive spectrometer. As the energies of the X-rays are characteristic of the difference in energy between the two shells and of the atomic structure of the emitting element, EDS allows the elemental composition of the specimen to be measured.
View the full Wikipedia page for Energy-dispersive X-ray spectroscopySample (material) in the context of Product sample
A product sample is a sample of a consumer product that is given to the consumer, often free of charge, so that they may try a product before committing to a purchase. When it comes to marketing non-durable commodities, such as food items, sampling is crucial. It gives room to highlight new items on the market as well as to bring back classic product categories with fresh tastes, inventive ingredients, and other changes.
View the full Wikipedia page for Product sample