Mueller bridge

Zettlemoyer et al. provided a detailed study of the use of a thermistor connected to a Mueller bridge as the temperature-sensing element in immersional calorimetry. Thermistor calorimeters have since gained wide use because of the simple construction and operation they make possible. Brief... 

Platinum Resistance Thermometer. Platinum resistance thermometers are based on the electrical resistance of Pt. This resistance for Pt wires wound on a mica support and enclosed in a glass or silica vessel can be manufactured to be either 25.5 Q at 0°C or 2.5 Q at 0°C. The electrical resistance, typically measured in a Wheatstone or Mueller bridge, increases by about 0.1 Q or 0.01 Q, respectively, per degree centigrade (0.4%/°C). Empirical equations convert Pt resistance and its small nonlinearities to temperature ... 

Calorimeter temperature was measured with a Leeds and Northrup G-l Mueller bridge used in conjunction with a d.c. Null Detector (No. 9834) or with a moving coil galvanometer (No. 2284-D) and lamp and scale. 

FIGURE 16.12 Mueller bridge circuit for precision resistance measurement. 

PRTs can have either two, three, or four lead wires. Besides the Mueller bridge setup, two-wire and three-wire bridges are available [24]. A two-wire (Wheatstone) bridge is the least accurate, because the lead-wire resistances are not accounted for. A three-wire bridge (shown in Fig. 16.14) allows for the compensation of lead-wire resistances by adding the resistance of the third lead wire to the leg of the bridge, where the known variable resistor resides. Hence,... 

The resistance of the platinum thermometer was measured by means of a Mueller bridge. The electrical input energy was determined from the measurements of the current and potential across a 100 Q Constantan wire heater and the time interval of heating. The heater current and potential were measured by means of a Wenner potentiometer in conjunction with a resistor and a volt box. The time interval of heating was measured by means of a precise interval timer. 

A Mueller bridge in conjunction with a lamp and scale galvanometer is used to read the standard thermometers as well as the test probes described earlier. 

A fully-automatic Mueller bridge has been described and an instrument of this type has been used at the National Bureau of Standards for heat capacity measurements. ... 

Accessories. Some forms of Wheatstone-bridge circuits are used for the measurement of temperature with base-metal or industrial platinum resistance thermometers, while the Mueller bridge is used with precision platinum resistance thermometers. 

There is ample literatime by the American Society of Mechanical Engineers (ASME), the American Society for Testing and Materials, the NBS, and others that deals with calibration methods, specifications for construction and usage of measuring instruments and temperature comparators, and processing of calibration data. It is advisable in each case to have the major components of the system (primary and secondary standards), potentiometers, and Mueller bridges calibrated periodically by the NBS or other qualified laboratory. 

Electrophilic addition of sulphenyl halides to alkenes occurs, by all the evidence, via cyclic thiiranium ions (Mueller, 1969) and a comparison of the rates of addition to the double and triple bond would be quite interesting. Unfortunately, direct kinetic data for strictly comparable and typical cases are not available. Phenylacetylene has been reported (Kharasch and Yannios, 1964) to react 102 times slower than styrene (in acetic acid at 25°) with 2,4-dinitrobenzenesulphenyl chloride. On the other hand, Thaler (1969), by means of competitive experiments carried out in dilute paraffin solutions at — 70°, estimated that methane-sulphenyl chloride adds to mono- (and di-)alkylacetylenes 50-100 times more slowly than to the corresponding alkenes (cis) (but only ca. twice slower than to trans dialkylethylenes). The paucity of information does not allow generalizations and further work in this area seems desirable also with respect to the much larger rate differences observed in those bromine additions to triple and double bonds which also occur via bridged species. 

Mueller-Storm HP, Sogo JM, Schaffner W. 1989. An enhancer stimulates transcription in trans when attached to the promoter via a protein bridge. Cell 58, 767-717. 

The first known instance of the synthesis of MOFs through an electrochemical route was performed by Mueller and coworkers, who pioneered a technique of anodic dissolution of the cation of a MOF metal centre within a solution of an organic bridging ligand and conducting salt, resulting in formation of, in this case, Cu-MOF (also known as HKUST-1 [Cu3(btc)2], btc = 1,3,5-benzenetricarboxylate, see Fig. 2) without side... 

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