Partial nitritation providing a suitable effluent for subsequent anammox is a critical step in a two-stage autotrophic nitrogen removal system. This study demonstrates an innovative approach for attaining partial nitritation in an acidic bioreactor operating at a slightly low pH (i.e., 5–6). This approach is based on our hypothesis in this study that acid-tolerant ammonia-oxidizing bacteria (AOB) can produce nitrite and protons to self-sustain free nitrous acid (FNA, NO2 – + H+ ↔ HNO2) at a parts per million level, as an inhibitor of nitrite-oxidizing bacteria (NOB). With influent nitrogen of about 200 mg/L and operating conditions of high dissolved oxygen, long sludge retention time, and moderate temperature, a lab-scale acidic bioreactor with FNA up to 2 mg of HNO2-N/L successfully established stable nitrite accumulation in the effluent for 200 days, with an average ratio [NO2 –/(NO2 – + NO3 –)] exceeding 95%. A 16S rRNA amplicon sequencing analysis showed that Nitrosospira was the dominant AOB in the biomass of the bioreactor, while Nitrosomonas and Nitrospira, two typical nitrifying genera in neutral wastewater treatment, both disappeared after the startup of partial nitritation. Kinetic characterization revealed that Nitrosospira had a substrate affinity of 11.4–16.5 mg of total ammonia (NH4 + + NH3)/L. It also revealed that less than 3.5 mg of HNO2-N/L FNA did not inhibit AOB activity significantly. Acidic operation is economically attractive because it can be achieved via acidophilic ammonia oxidation without adding chemical acid. However, hazardous gas, nitric oxide (NO), should be removed from gas produced by acidic nitrifying bioreactors.

B cell dysfunction due to obesity can be associated with alterations in the levels of micro-RNAs (miRNAs). However, the role of miRNAs in these processes remains elusive. Here, we show that miR-802 is increased in the pancreatic islets of obese mouse models and demonstrate that inducible transgenic overexpression of miR-802 in mice causes impaired insulin transcription and secretion. We identify Foxo1 as a transcription factor of miR-802 promoting its transcription, and NeuroD1 and Fzd5 as targets of miR-802-dependent silencing. Repression of NeuroD1 in β cell and primary islets impairs insulin transcription and reduction of Fzd5 in β cell, which, in turn, impairs Ca 2+ signaling, thereby repressing calcium influx and decreasing insulin secretion. We functionally create a novel network between obesity and β cell dysfunction via miR-802 regulation. Elucidation of the impact of obesity on microRNA expression can broaden our understanding of pathophysiological development of diabetes.

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Motion process monitoring is the core component of motion state analysis system and motion safety assurance system. For the water sport, implementation of monitoring is directly related to the safety and security of sportsmen, which is more significant. This paper presents a kind of underwater sports safety monitoring system based on radar idea. The system consists of four parts: video acquisition, image processing, data sample comparison and signal transmission. Reasonable cameras are used to capture the whole swimming pool, and then the motion information parameters of the swimmers are obtained by image segmentation and tracking, and compared with the standard drowning behavior parameters, so as to determine whether the swimmers are drowning or not. If it is judged that a person may be drowning, the system will send out a corresponding rescue signal, which will quickly alert and notify rescuers through the wireless signal transmission system, so as to rescue those who may be drowning, so as to enhance the safety of people’s movement in the water. The drowning behavior is identified by the established drowning feature data sample set, which avoids the occurrence of invisible drowning events that are difficult to detect. By using the high-speed DSP, the data processing and alarm system’s timely response can be realized, which greatly shortens the rescue time, directly improves the survival probability of drowning and reduces the physiological damage. The design of the monitoring system will eventually help the lifeguards to complete the task of underwater movement safety.