Treatment of Phenol Wastewater with Cu-Fe/AC Catalyst by Continuous CWPO

The Cu-Fe/AC catalyst was prepared by microwave-assisted synthesis, and its morphological characteristics were characterized. The degradation effect of phenol wastewater by catalytic wet peroxide oxidation(CWPO) was studied, and the response surface methodology(RSM) was used to analyze the influencing factors of the removal rate of COD. The experimental results showed that under the conditions of reaction temperature 80 ℃, reaction time 90 min, initial pH 3.1 and H_(2)O_(2)addition 2.2 g/L, the removal rate of COD reached 82%. The results of response surface methodology indicated that under the conditions of reaction temperature 100 ℃, reaction time 64 min, initial pH 3.3 and H_(2)O_(2)addition 2.7 g/L, the removal rate of COD was up to 86%. After Cu-Fe/AC catalyst was reused for 4 times, the removal rate of COD was still above 80%, revealing that the catalyst showed good catalytic performance.

Template-guided frequency attention and adaptive cross-entropy loss for UAV visual tracking

This paper addresses the problem of visual object tracking for Unmanned Aerial Vehicles(UAVs).Most Siamese trackers are used to regard object tracking as classification and regression problems.However,it is difficult for these trackers to accurately classify in the face of similar objects,background clutters and other common challenges in UAV scenes.So,a reliable classifier is the key to improving UAV tracking performance.In this paper,a simple yet efficient tracker following the basic architecture of the Siamese neural network is proposed,which improves the classification ability from three stages.First,the frequency channel attention module is introduced to enhance the target features via frequency domain learning.Second,a template-guided attention module is designed to promote information exchange between the template branch and the search branch,which can get reliable classification response maps.Third,adaptive cross-entropy loss is proposed to make the tracker focus on hard samples that contribute more to the training process,solving the data imbalance between positive and negative samples.To evaluate the performance of the proposed tracker,comprehensive experiments are conducted on two challenging aerial datasets,including UAV123 and UAVDT.Experimental results demonstrate that the proposed tracker achieves favorable tracking performances in aerial benchmarks beyond 41 frames/s.We conducted experiments in real UAV scenes to further verify the efficiency of our tracker in the real world.

Nitrous oxide emissions from black soils with different pH

N2O fluxes as a function of incubation time from soil with different available N contents and pH were determined. Cumulative carbon dioxide （CO2） emissions were measured to indicate soil respiration. A 144-hr incubation experiment was conducted in a slightly acidic agricultural soil （PHH2o 5.33） after the pH was adjusted to four different values （3.65, 5.00, 6.90 and 8.55）. The experiments consisted of a control without added N, and with NH^-N and NO^-N fertilization. The results showed that soil pH contributed significantly to N20 flux from the soils. There were higher N20 emissions in the period 0-12 hr in the four pH treatments, especially those enhanced with N- fertilization. The cumulative NEO-N emission reached a maximum at pH 8.55 and was stimulated by NO3-N fertilization （70.4 μg/kg）. The minimum emissions appeared at pH 3.65 and were not stimulated by NO3^--N or NH4^＋-N fertilization. Soil respiration increased significantly due to N-fertilization. Soil respiration increased positively with soil pH （R2 = 0.98, P 〈 0.01）. The lowest CO2-C emission （30.2 mg/kg） was presented in pH 3.65 soils without N-fertilization. The highest CO2-C emissions appeared in the pH 8.55 soils for NH4^＋-N fertilization （199 mg/kg）. These findings suggested that N20 emissions and soil respiration were significantly influenced by low pH, which strongly inhibits soil microbial nitrification and denitrification activities. The content of NO3^--N in soil significantly and positively affected the N2O emissions through denitrification.

Heterotrophy-coordinated diazotrophy is associated with significant changes of rare taxa in soil microbiome

Soil heterotrophic respiration during decomposition of carbon(C)-rich organic matter plays a vital role in sustaining soil fertility.However,it remains poorly understood whether dinitrogen(N_(2))fixation occurs in support of soil heterotrophic respiration.In this study,^(15)N_(2)-tracing indicated that strong N_(2)fixation occurred during heterotrophic respiration of carbon-rich glucose.Soil organic ^(15)N increased from 0.37 atom%to 2.50 atom%under aerobic conditions and to 4.23 atom%under anaerobic conditions,while the concomitant CO_(2)flux increased by 12.0-fold under aerobic conditions and 5.18-fold under anaerobic conditions.Soil N_(2)fixation was completely absent in soils replete with inorganic N,although soil N bioavailability did not alter soil respiration.High-throughput sequencing of the 16S rRNA gene further indicated that:i)under aerobic conditions,only 15.2%of soil microbiome responded positively to glucose addition,and these responses were significantly associated with soil respiration and N_(2)fixation and ii)under anaerobic conditions,the percentage of responses was even lower at 5.70%.Intriguingly,more than 95%of these responses were originally rare with<0.5%relative abundance in background soils,including typical N_(2)-fixing heterotrophs such as Azotobacter and Clostridium and well-recognized non-N_(2)-fixing heterotrophs such as Sporosarcina,Agromyces,and Sedimentibacter.These results suggest that only a small portion of the soil microbiome could respond quickly to the amendment of readily accessible organic C in a fluvo-aquic soil and highlighted that rare phylotypes might have played more important roles than previously appreciated in catalyzing soil C and nitrogen turnovers.Our study indicates that N_(2)fixation could be closely associated with microbial turnover of soil organic C when available in excess.