Peltier Elements

Peltier elements are solid-state heat pumps that make use of the Peltier effect to create a hot side and a cool side of the element. Peltier elements are common in electronic components in laboratory equipment. They are relatively small, silent, and have no moving parts. This makes them reliable. Peltier elements are operated by a direct current (d.c.) and, by reversing the polarity of the current, one can alternate heating and cooling. The amount of heat transferred is proportional to the current that flows through the element. The block temperature may not be uniform throughout the element, particularly the corners may deviate, which might affect reaction efficiency. Temperature variations within the block are usually within ±0.5°C after holding at constant temperature for a certain amount of time. Peltier elements can create temperature gradients, giving extra flexibility when, for example, optimizing annealing temperatures in PCR. Instruments that use Peltier elements usually have rather slow heating and cooling ramp rates. They are typically of 1-5°C/sec because of large thermal inertia, which cause a regular PCR run of 40 cycles in approximately 90 min. Real-time PCR instruments that use Peltier elements include the Bio-Rad iCycler and MyCycler, ABI, real-time PCR instruments, MJ Research DNA Engine Opticon, Techne Quantica and Stratagene Mx4000/Mx3000p.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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