Effects of carbon to nitrogen ratio on nitrogen removal in a single-stage microaerobic system: A model-based evaluation.

Single-stage microaerobic systems have been proven to be effective for concurrent removal of ammonium and organic carbon from sewage. While mechanistic models derived from activated sludge models (ASMs) have simulated nutrients removal under microaerobic conditions, classic ASMs exhibit limitations in capturing the intricate effects of carbon to nitrogen (C/N) ratio on nitrogen removal performance. To address this issue, a mechanistic model modified from the classic ASMs was proposed to capture the combined inhibitory effects of carbon and ammonium on microaerobic systems. This modified model was established based on experimental data from a single-stage microaerobic reactor encompassing simultaneous nitrification-denitrification and anammox processes. The inhibition coefficient of C/N ratio was integrated into the process rate equations, and its effectiveness was validated through model performance evaluation. Compared to the classic models, the modified one achieved superior predictions for nitrite and nitrate nitrogen concentrations. Simulations revealed that under optimized conditions with a C/N of 4.57 and a dissolved oxygen (DO) of 0.41 mg/L, the system could achieve up to 95.5% of total nitrogen (TN) removal efficiency. Based on the simulation of substrate uptake/production rate, increasing the nitrogen loading rate (NLR) rather than organic loading rate (OLR) was crucial for efficient nitrogen removal. The proposed modified model served as a valuable tool for designing and optimizing similar biological wastewater treatment systems.

Eutrophication-driven infochemical dimethylsulfide accelerates carbon transfer in freshwater food chain.

Dimethylsulfide (DMS) is a major organic sulfide in aquatic ecosystems and an infochemical that is considered as a key predictor of changes in energy and material fluxes and stocks. It is largely unknown how DMS changes and affects the food webs and material cycles in eutrophicated freshwater. In this study, field monitoring and literature surveys were conducted to analyze the effects of eutrophication on DMS concentrations. Daphnia-zebrafish microcosms were then used to investigate the effects of DMS concentrations on carbon transfer. The results demonstrated that the concentration of DMS was increased by eutrophication related indicators (chlorophyll and phosphorus). Eutrophication driven DMS altered carbon transfer in the freshwater food chain. Low concentrations (0.1-1 nM) of DMS promoted the predation of daphnia by zebrafish compared to the 0.01 nM DMS, which further stimulated the total carbon transfer from daphnia to zebrafish and altered the dissolved organic carbon (DOC) distribution in water. High concentrations (10-100 nM) of DMS did not alter zebrafish predation on daphnia and carbon transfer. DOC excreted by zebrafish altered carbon emission potential, and DMS in water showed a unimodal relationship with the carbon emission potential, peaking at 0.40 nM DMS. Keeping the DMS in water at 1.82 nM may maintain a lower carbon emission potential. These results improved the understanding of the effects of eutrophication on DMS, demonstrated the ecological role of DMS on freshwater fish and the carbon cycle, estimated the effects of DMS on the carbon emission potential of fish, and offered new insights into the management of eutrophication.

Coupling and decoupling of soil carbon and nutrients cycles at different salinity levels in a mangrove wetland: Insights from CUE and enzymatic stoichiometry.

Soil carbon (C), nitrogen (N), and phosphorus (P) cycling, in conjunction with microbial metabolism, varies significantly with salinity in coastal areas. However, microbial metabolism limitation on salinity levels has received limited attention. Based on soil microbial carbon use efficiency and enzymatic stoichiometry, microbial nutrient limitation characteristics of soil microbial communities in different salinity levels (4.45 mS·cm-1 - 17.25 mS·cm-1) in a subtropical mangrove wetland were investigated. Compared to low-salinity levels, the activity of soil C-acquiring enzyme activities, enzymatic C:N ratios and enzymatic C:P ratios decreased with medium salinity levels and high salinity levels. Soil microbial metabolism was primarily constrained by C and N at different salinity levels. Boosted regression tree analysis revealed that abiotic factors had the greatest influence on C and N limitation of microbial metabolism at different salinity levels. This study underscores the significance of salinity in microbial metabolic processes and enhances our understanding of how future salinity changes induced by rising sea levels will affect soil carbon and nutrient cycling in coastal wetlands.

3D single-pixel imaging at the near-infrared wave band.

Focal plane detector array technology in the infrared wave band is expensive or underdeveloped, and the detection efficiency is low, while single-pixel imaging (SPI) offers better performance, such as ultrafast time response and high quantum efficiency in wide wave bands. Therefore, SPI technology can be used for infrared imaging. In this work, a near-infrared raster scan SPI system is proposed. By means of a grating to modulate height information of objects, we can further achieve three-dimensional imaging in the framework of Fourier transform profilometry. The proposed approach is demonstrated with experiments at the wavelength of 1064 nm.

Lower urinary tract symptoms in an elderly women caused by degeneration of the pubic symphysis.

BACKGROUND: Lower urinary tract symptoms are very common in elderly women, and transvaginal delivery and multiple deliveries have been confirmed to be risk factors. Transvaginal delivery and multiple deliveries may lead to an increase in pubic symphysis degeneration. CASE PRESENTATION: A 79-year-old woman consulted a urologist because of worsening lower urinary tract symptoms such as frequent urination and urodynia. Color ultrasound and cystoscopy suggested the possibility of a bladder mass. A lump on the anterior wall of the bladder was observed although the surface mucosa was normal. Physical examination showed obvious tenderness in the posterior area of the pubic symphysis. Further urological computed tomography (CT) and pelvic magnetic resonance imaging (MRI) showed a nodular bony protuberance in the posterior part of the pubic symphysis, which was more obvious than before, with compression changes near the anterior wall of bladder. Open pelvic surgery showed that nodular bone tissue originating from the pubic symphysis significantly oppressed the anterior wall of the bladder behind the pubic symphysis. After resection of the nodule, the lower urinary tract symptoms were relieved significantly. CONCLUSIONS: Pubic symphysis degeneration caused by transvaginal delivery may be an important cause of lower urinary tract symptoms in women. Pelvic CT or MRI is necessary to diagnosis this condition.

Comparative pharmacokinetics of chlorogenic acid after oral administration in rats.

The present study was aimed at the comparison of the pharmacokinetics of pure chlorogenic acid and extract of Solanum lyratum Thunb. The animals were allocated to two groups, and were administered chlorogenic acid or extract of S. lyratum Thunb. at a dose of 50.0 mg/kg orally. Blood samples were collected up to 8 h post-dosing. Plasma chlorogenic acid analyses were performed using an HPLC method with UV detector. The pharmacokinetic parameters were evaluated using non-compartmental assessment. Significant differences existed in the two groups for AUC0-t , AUC0-∞ and CLz/F. The reliable HPLC method was successfully applied to the determination of chlorogenic acid in rat plasma at dosage of 50.0 mg/kg.