Switches mechanical thermal

The sample is then isolated from the helium bath, usually by disengaging a mechanical thermal switch. After this thermal isolation of the sample, the magnetic field is removed, and the magnetic moments of the electrons resume a random arrangement. During the randomization process, the electronic system... 

Other types of thermal switches have been built, e.g. mechanical switches which can be turned on and off easily, but which produce heat in the switching and are therefore used at T > IK. Thermal contact is made by pressing together metallic surfaces. Conductance of a few mW/K can be obtained in the on state [14,30,41-45]. Another disadvantage of these switches are the large forces (typically 10 kg) needed to produce a good contact. Nowadays, the use of these switches is not common. 

Thermoelectric flame failure detection Analog burner control systems Safety temperature cut-out Mechanical pressure switch Mechanic/pneumatic gas-air-ration control Thermoelectric flame supervision Thermal combustion products, discharge safety devices Electronic safety pilot Electronic burner control systems Electronic cut-out with NTC Electronic pressure sensor/transmitter Electronic gas-air-ration control with ionisation signal or 02 sensor Ionisation flame supervision Electronic combustions product discharge safety device... 

Thermally switched liquid crystal alignments can be obtained with a rubbed PVK film [70]. A mechanically rubbed PVK layer can induce a planar alignment of liquid crystals with their axis direction perpendicular to the direction of rubbing. This direction can be switched toward the rubbing direction by a thermal treatment. A possible application of such a device is for polarization rotators. The PVK film does... 

Argon Gap -Heat Transfer -Thermal Switch Mechanism... 

The AHTR uses a guard vessel for two functions. The first function is part of a thermal switch mechanism that ensures low losses of heat during normal operations but efficient removal of decay heat during shutdown or off normal conditions. The second function of the guard vessel is to provide a backup in the event of vessel failure and catch the core and the liquid salt within the core. 

If we consider that the stability constant for the complex is K< =k,. .pi.,/kA., pi. the requirement for a carrier is that the same molecule have a large and small decomplexation rate at the same time. Since this is impossible, compounds are chosen that achieve transport by a compromise of the complexation and decomplexation rate constants. One means of circumventing this problem is to use a ligand (binder) that can be made to form a more or less stable complex by a rapid chemical modification. This is usually referred to as "switching." Mechanisms to switch a ligand s binding ability based on ionization, thermal, photochemical, and redox properties have been described in the literature. 

Figure 4.1 Schematic diagram of a coupled column system. The first column (ID) is connected to the second column (2D) tlirough the interface or valve system. The interface can be a diiect coupling, a live T-union, a complex multiport valve, or a thermal or cryogenic modulation system. The stimulus can be the switching of the valve, abalancing pressure to divert flow towards 2D, an added flow that is used in pressure tuning, or the drive mechanism for the modulator. The line to detector 1 will normally be a non-retaining section of column. In a two-oven system, ID and 2D will be in different ovens the dotted line indicates separately heated zones.

In the case of LNT, different proposals have been advanced to explain the mechanisms governing the NO, release. Recent papers suggested that the NO release is provoked by the heat generated upon the reducing switch (thermal release) [40], by the decrease of the gas-phase oxygen concentration that destabilizes the stored nitrates [41], by spillover and reduction of N02 onto reduced Pt sites or by the establishment of a net reducing environment, which decreases the equilibrium stability of nitrates [12,42,43],... 

The incorporation of Cr" + ions in crystals is presently an active research subject, due to the possibility of realizing new broadly tunable solid state lasers in the infrared, which will operate at room temperature. Moreover, the spectroscopic properties of this ion are particularly useful in the development of saturable absorbers for Q-switching passive devices. At the present time, Cr + YAG is the most common material employed as a passive Q-switch in Nd YAG lasers. This is because the ions provide an adequate absorption cross section at the Nd + laser wavelength (1.06 /um), together with the good chemical, thermal, and mechanical properties of YAG crystals, which are required for stable operation. 

HNF, N2H5C(N02)3, melts at 397 K and completely decomposes at 439 K, accompanied by an energy release of 113 kJ moTk DTA and TG analyses reveal that the thermal decomposition of HNF occurs in two steps. The first step is an exothermic reaction accompanied by 60% mass loss in the temperature range 389-409 K. The second step is another exothermic reaction accompanied by 30% mass loss in the temperature range 409-439 K. These two steps occur successively and the decomposition mechanism seems to switch at 409 K. 

We show here that when an enzyme is immobilized within such gels it may be "switched" on and off reversibly as the temperature is cycled. Such catalytic hydrogels may be used to control reactions by a thermal feedback mechanism. 

---