Abstract: Provided are a rolling circle amplification method, a method for preparing a sequencing library, and a DNA nanoball prepared therefrom. The rolling circle amplification method includes: sequentially denaturing and annealing a double-stranded DNA and a mediating sequence in a same system, to complementarily pair the mediating sequence with two ends of a denatured single-stranded DNA; simultaneously introducing a ligase and a polymerase into the system to connect the two ends of the single-stranded DNA under action of the ligase; and performing a rolling circle amplification reaction under action of the polymerase by using the mediating sequence as a primer and the single-stranded DNA as a template, to obtain DNA nanoball.

Abstract: The invention relates to a gas-liquid heat exchanger comprising a first liquid distributor, a second liquid distributor and heat exchange assemblies connecting the first liquid distributor and the second liquid distributor. A flow equalizer plate and a liquid guiding plate are arranged on the first liquid distributor to equalize the incoming liquid. On the heat exchange assemblies are arranged longitudinally-finned tubes, which are evenly distributed in an array. The fins on two adjacent longitudinally-finned tubes are arranged in an alternating manner to achieve heat exchange assemblies providing small wind resistance, large heat transfer surface area and long heat transfer stroke. Therefore, the heat exchanger has uniform liquid distribution, small wind resistance, large heat transfer surface area, long heat transfer stroke, gas-liquid counter-flow arrangement and high heat transfer efficiency.

Abstract: The invention relates to a gas-liquid heat exchanger comprising a first liquid distributor, a second liquid distributor and heat exchange assemblies connecting the first liquid distributor and the second liquid distributor. A flow equalizer plate and a liquid guiding plate are arranged on the first liquid distributor to equalize the incoming liquid. On the heat exchange assemblies are arranged longitudinally-finned tubes, which are evenly distributed in an array. The fins on two adjacent longitudinally-finned tubes are arranged in an alternating manner to achieve heat exchange assemblies providing small wind resistance, large heat transfer surface area and long heat transfer stroke. Therefore, the heat exchanger has uniform liquid distribution, small wind resistance, large heat transfer surface area, long heat transfer stroke, gas-liquid counter-flow arrangement and high heat transfer efficiency.

Abstract: The present invention relates to a precision air conditioner with an indirect evaporative unit, which comprises a gas-gas heat exchanger, an external circulation fan, an internal circulation fan, a gas filter module, a gas humidification module, an evaporator, a condenser, a condenser fan, a compressor and an air conditioner enclosure. The combination of indirect evaporative cooling and mechanical refrigeration enables indirect evaporative cooling to operate all year round with high air conditioning and refrigeration efficiency. During summer, mechanical refrigeration is used for secondary cooling to achieve the desired temperature. Further, the condenser of the precision air conditioner is upgraded to an indirect evaporative condenser, and the mechanical refrigeration efficiency can be greatly improved.