Re-evaluation and modification of dehydrogenase activity tests in assessing microbial activity for wastewater treatment plant operation.

Reliable and cost-effective methods for monitoring microbial activity are critical for process control in wastewater treatment plants. The dehydrogenase activity (DHA) test has been recognized as an efficient measure of biological activity due to its simplicity and broad applicability. Nevertheless, the existing DHA test methods suffer from imperfections and are difficult to implement as routine monitoring techniques. In this work, an accurate and cost-effective modified DHA approach was developed and the procedure for the DHA test was critically evaluated with respect to the standard construction, sample pretreatment, incubation and extraction conditions. The feasibility of the modified DHA test was demonstrated by comparison with the oxygen uptake rate and adenosine triphosphate in a sequencing batch reactor. The sensitivities of the two typical tetrazolium salts to toxicant inhibition by heavy metals and antibiotics were compared, revealing that 2,3,5-triphenyltetrazolium chloride (TTC) exhibited a higher sensitivity. Furthermore, the sensitivity mechanism of the two DHA tests was elucidated through electrochemical experiments, theoretical analysis and molecular simulations. Both tetrazolium salts were found to be effective artificial electron acceptors due to their low redox potentials. Molecular docking simulations revealed that TTC could outperform other tetrazolium salts in accepting electrons and hydrogens from dehydrogenase. Overall, the modified DHA approach presents an accurate and cost-effective way to measure microbial activity, making it a practical tool for wastewater treatment plants.

[Method and application of proteomics in study of targets of traditional Chinese medicines].

The study on the targets of traditional Chinese medicine is an important part of researchers using modern scientific language to clarify the mechanism of traditional Chinese medicine. However, the research on the targets of Chinese medicine is full of challenges due to the complexity of active ingredients. As a branch of systems biology, proteomics focus on specific proteins in living organisms from a holistic perspective, which significantly improves the efficiency of targets discovery and has obvious advantages in the research of targets of Chinese medicine. Based on relevant literature and different methods used in targets of Chinese medicine, proteomics can be divided into chemical proteomics, differential proteomics and quantitative proteomics. The applications of the above three methods are illustrated in this paper as well, which will provide new methods and ideas for the study of the mechanism of Chinese medicine in the future.

Enhanced adsorption of arsenite from aqueous solution by an iron-doped electrospun chitosan nanofiber mat: Preparation, characterization and performance.

A novel iron-doped chitosan electrospun nanofiber mat (Fe@CTS ENM) was synthesized, which was proven to be effective for the removal of arsenite (As(III)) from water at neutral pH condition. The physiochemical properties and adsorption mechanism were explored by SEM-EDS and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments were carried out to evaluate the As(III) adsorption performance of the Fe@CTS ENM with various process parameters, such as adsorbent dose, solution pH, initial As(III) concentration, contact time, ionic strength, coexisting anions, and natural organic matter. The experimental results indicated that the maximum adsorption capacity was up to 36.1 mg g-1. Especially, when the adsorbent dosage was higher than 0.3 g L-1, the As(III) concentration was reduced from 100 µg L-1 to less than 10 µg L-1, which indicated the Fe@CTS ENM could effectively remove trace As(III) from water over a wide pH range (from 3.3 to 7.5). Kinetics study demonstrated that the adsorption equilibrium was achieved within 2.0 h, corresponding to a fast uptake of As(III). The presence of common co-ions and humic acid had little effect on the As(III) adsorption. XPS analysis suggested that the FeO, COH, COC and CN groups on the adsorbent surface play dominant roles in the adsorption of As(III). Adsorption-desorption regeneration test further demonstrated that no appreciable loss in the adsorption capacities was observed, which confirmed that the Fe@CTS ENM maintained a desirable life cycle that was free of complex synthesis processes, expensive and toxic materials, qualifying it as an efficient and low-cost As(III) adsorbent.

Assessment of the fate of silver nanoparticles in the A(2)O-MBR system.

In this study, we employed a bench scale A(2)O-MBR (anaerobic-anoxic-oxic membrane bioreactor) system to systematically investigate the behavior and distribution of silver nanoparticles (AgNPs) in the activated sludge. The results showed that AgNPs would aggregate and form Ag-sulfur complexes in the activated sludge, and the dissolved silver only reached 13.6 µg/L when AgNPs of 5mg/L was spiked into the A(2)O-MBR. The long-term mass balance analysis showed that most of the silver contents were accumulated in the bioreactor and wasted excess sludge. Only a small fraction (less than 0.5%) of silver could get across the hollow fiber membranes with 0.1 µm nominal pore size in the effluent. In addition, the comparison between total AgNP concentration in aerobic sludge supernatant and effluent suggested that the membrane modules played a role in controlling the discharge of AgNPs into the effluent, especially under a higher influent concentration of AgNPs. Our results also showed that the adsorbed AgNPs or silver complexes in activated sludge still could release dissolved silver at the ambient pH. Thus, since activated sludge could be a sink for AgNPs, the risks of AgNPs in wasted excess sludge during utilization and disposal should be further studied.

Early change of plasma and cerebrospinal fluid arginine vasopressin in traumatic subarachnoid hemorrhage.

OBJECTIVE: To investigate the changes and effects of arginine vasopressin (AVP) in patients with acute traumatic subarachnoid hemorrhage (tSAH). METHODS: The plasma and cerebrospinal fluid (CSF) level of AVP, and intracranial pressure (ICP) were measured in a total of 21 patients within 24 hours after tSAH. The neurological status of the patients was evaluated by Glasgow Coma Scale (GCS). Correlation between AVP and ICP, GCS was analyzed respectively. Meanwhile, 18 healthy volunteers were recruited as control group. RESULTS: Compared with control group, the levels (pg/ml) of AVP in plasma and CSF (x+/-s) in tSAH group were significantly increased within 24 hours (38.72+/-24.71 vs 4.54+/-1.38 and 34.61+/-21.43 vs 4.13+/-.26, P less than 0.01), and was remarkably higher in GCS less than or equal to 8 group than GCS larger than 8 group (50.96+/-36.81 vs 25.26+/-12.87 and 44.68+/-31.72 vs 23.53+/-10.94, P less than 0.05). The CSF AVP level was correlated with ICP (r eqaul to 0.46, P less than 0.05), but no statistically significant correlation was found between plasma AVP, CSF AVP and initial GCS (r equal to -0.29, P larger than 0.05 and r equal to -0.32, P larger than 0.05, respectively). The ICP (mm Hg) in tSAH patients was elevated and higher in GCS less than or equal to 8 group than in GCS larger than 8 group (25.9+/-9.7 vs 17.6+/-5.2, P less than 0.05). CONCLUSION: Our research suggests that AVP is correlated with the severity of tSAH, and may be involved in the pathophysiological process of brain damage in the early stage after tSAH. It seems that compared with the plasma AVP concentration, CSF AVP is more related to the severity of tSAH.