Class-D amplifierA class-D amplifier or switching amplifier is an electronic amplifier in which the amplifying devices (transistors, usually MOSFETs) operate as electronic switches, and not as linear gain devices as in other amplifiers. They operate by rapidly switching back and forth between the supply rails, using pulse-width modulation, pulse-density modulation, or related techniques to produce a pulse train output. This passes through a simple low-pass filter which blocks the high-frequency pulses and provides analog output current and voltage.
Amplificateur de mesureUn amplificateur de mesure (en anglais Instrumentation Amplifier, in-amp ou INA) est un dispositif électronique destiné au traitement de faibles signaux électriques. On le trouve également dans la littérature sous le nom d'amplificateur d'instrumentation. L'amplificateur de mesure est un élément essentiel dans la partie de conditionnement d'une chaîne d'acquisition : il permet le traitement de signaux issus de capteurs de mesure.
Méthode de KjeldahlLa méthode de Kjeldahl est une technique de détermination du taux d'azote dans un échantillon. Elle est applicable pour le dosage de l’azote de différents composés azotés tels les amines et les sels d’ammonium quaternaires. Elle ne permet pas le dosage direct des nitrates, nitrites, nitrosyles, cyanures qui doivent d’abord être réduits en ammoniac. Quand l’azote est sous forme organique, on procède d'abord à la minéralisation du composé pour passer à de l’azote minéral.
Liberation (pharmacology)Liberation is the first step in the process by which medication enters the body and liberates the active ingredient that has been administered. The pharmaceutical drug must separate from the vehicle or the excipient that it was mixed with during manufacture. Some authors split the process of liberation into three steps: disintegration, disaggregation and dissolution. A limiting factor in the adsorption of pharmaceutical drugs is the degree to which they are ionized, as cell membranes are relatively impermeable to ionized molecules.
Le Chatelier's principleLe Chatelier's principle (pronounced UKlə_ʃæˈtɛljeɪ or USˈʃɑːtəljeɪ), also called Chatelier's principle (or the Equilibrium Law), is a principle of chemistry used to predict the effect of a change in conditions on chemical equilibria. The principle is named after French chemist Henry Louis Le Chatelier, and sometimes also credited to Karl Ferdinand Braun, who discovered it independently.
