Related Concept Videos

Upward Impending Motion01:21

Upward Impending Motion

A square-threaded screw jack is a mechanical device widely used for lifting heavy loads or applying considerable force. Its operation is based on converting the force applied at its handle into a torsional moment, causing the upward impending motion of the screw. This movement is accomplished by overcoming the static friction between the threads of the screw and the jack.
To better comprehend how a screw jack functions, consider the completely unraveled thread as a block in contact with the...
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Transition Zone01:28

Transition Zone

The transition zone in concrete is a critical area where aggregate meets cement paste, marked by a distinct porosity and weakness compared to the surrounding material. The adhesion around the aggregates is primarily due to Van Der Waals forces. The voids within this zone influence its robustness; initially, it is less durable than the surrounding bulk mortar due to larger voids. Initially, when concrete is compacted, a higher water-cement ratio near the aggregates leads to the formation of...
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Crossing Over01:30

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I,...
4.7K
Urea Cycle01:23

Urea Cycle

The urea cycle describes how liver cells convert ammonia to urea. Ammonia is a toxic waste product of protein catabolism. Land animals must convert ammonia into the less toxic urea which can be safely eliminated by the kidneys through urine. Marine animals excrete ammonia directly, and the surrounding water dilutes the ammonia to safe levels.
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Leaving Groups02:14

Leaving Groups

The nature of leaving groups strongly influences the outcome of a nucleophilic substitution reaction.
In general, in a nucleophilic substitution reaction, a nucleophile displaces a functional group, called the leaving group, from the substrate to give a substituted product. A leaving group departs the substrate molecule through heterolytic cleavage, taking the pair of electrons with it to become a relatively stable weak base in the form of an anion or a neutral molecule.  
In a...
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Latitudes and Departures01:27

Latitudes and Departures

Latitudes and departures are essential concepts in surveying, providing a systematic way to analyze the projections of traverse lines. These projections allow surveyors to interpret a line's north-south and east-west components, which are crucial for precisely calculating areas, bearings, and lengths. Latitude is the north-south projection of a line, calculated as the product of the line's length and the cosine of its bearing. Departure, conversely, is the east-west projection obtained by...
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