Search

In order to study the effects of potato starch processing wastewater on nutrients and heavy metals in soils, we selected six potato starch production enterprises in Guyuan City, Ningxia and measured soil nutrients and heavy metals on farmlands irrigated with potato starch wastewater from commercial processing companies. Paired t-tests and comprehensive index evaluations were used to test changes in soil nutrients and heavy metals in farmland soil samples with and without irrigation using potato starch processing wastewater. No significant difference in heavy metals was observed between the two treatments (P>0.05). We also found no significant differences using comprehensive index evaluation, indicating no significant differences between treatments regarding soil quality, as confirmed by the previous analysis. Moreover, soil nutrient content was significantly improved on farmlands irrigated with potato starch processing wastewater (PI) evaluation method of the grading standard also indicated significantly increased soil nutrients on farmland with potato starch processing wastewater irrigation (I=83) when compared with soils that did not receive wastewater irrigation (intermediate level, I=53). Therefore, our results suggest that irrigation with potato starch processing wastewater increases soil fertility without significantly increasing soil heavy metal content.

A C-band high efficiency and high gain two-stage power amplifier based on AlGaN/GaN high electron mobility transistor (HEMT) is designed and measured in this paper. The input and output impedances for the optimum power-added efficiency (PAE) are determined at the fundamental and 2nd harmonic frequency (f0 and 2f0). The harmonic manipulation networks are designed both in the driver stage and the power stage which manipulate the second harmonic to a very low level within the operating frequency band. Then the inter-stage matching network and the output power combining network are calculated to achieve a low insertion loss. So the PAE and the power gain is greatly improved. In an operation frequency range of 5.4 GHz‐5.8 GHz in CW mode, the amplifier delivers a maximum output power of 18.62 W, with a PAE of 55.15% and an associated power gain of 28.7 dB, which is an outstanding performance.