Evaluation of simultaneous autotrophic and heterotrophic denitrification processes and bacterial community structure analysis.

This study demonstrated that a combined heterotrophic and autotrophic denitrification (HAD) process is highly effective for the simultaneous removal of acetate, nitrate, and sulfide at an efficiency of 100, 80, and 100 %, respectively. In the HAD system, simultaneous sulfide, acetate, and nitrate removals were observed, which indicated that heterotrophic and autotrophic denitrification occurred simultaneously. When the sulfide was existed in HAD reactor, the main product of sulfide biooxidation was S(0). Once the sulfide was exhausted, the sulfate concentration in the HAD reactor increased and became the main end product. These results provided an alternative method to control the end sulfide biooxidation product by online monitoring sulfide concentration. Nearly half (43 %) of the total clones in our mix-trophic reactor were amphitrophy denitrifiers. The autotrophic denitrifiers, heterotrophic denitrifiers, and amphitrophy denitrifiers coexisted in the HAD reactor to complete the denitrification process. Retrieved bacterial 16S rRNA gene clones affiliated with uncultured Xanthomonadaceae, Thauera, Thiobacillus, and Chromatiales were dominant.

The heterotrophic-combined-with-autotrophic denitrification process: performance and interaction mechanisms.

In this work, the interaction mechanisms between an autotrophic denitrification (AD) and heterotrophic denitrification (HD) process in a heterotrophic-autotrophic denitrification (HAD) system were investigated, and the performance of the HAD system under different S/Ac(-) molar ratios was also evaluated. The results demonstrated that the heterotrophic-combined-with-autotrophic denitrification process is a promising technology which can remove chemical oxygen demand (COD), sulfide and nitrate simultaneously. The reduction rate of NO(3)(-) to NO(2)(-) by the HD process was much faster than that of reducing NO(2)(-) to N2, while the reduction rate of NO(3)(-) to NO(2)(-) by the AD process was slower than that of NO(2)(-) to N2. Therefore, the AD process could use the surplus NO(2)(-) produced by the HD process. This could alleviate the NO(2)(-)-N accumulation and increase the denitrification rate. In addition, the inhibition effects of acetate on AD bacteria and sulfide on HD were observed, and the inhibition was compensated by the promotion effects on NO(2)(-). Therefore, the processes of AD and HD seem to react in parallel, without disturbing each other, in our HAD system.

Comparison of Behavioral Effects of GABAergic Low- and High-Efficacy Neuroactive Steroids in the Zebrafish Larvae Assay.

Activation of the GABAA receptor is associated with numerous behavioral end points ranging from anxiolysis to deep anesthesia. The specific behavioral effect of a GABAergic compound is considered to correlate with the degree of its functional effect on the receptor. Here, we tested the hypothesis that a low-efficacy allosteric potentiator of the GABAA receptor may act, due to a ceiling effect, as a sedative with reduced and limited action. We synthesized a derivative, named (3α,5ß)-20-methyl-pregnane-3,20-diol (KK-235), of the GABAergic neurosteroid 5ß-pregnane-3α,20α-diol. Using electrophysiology, we showed that KK-235 is a low-efficacy potentiator of the synaptic-type α1ß2γ2L GABAA receptor. In the zebrafish larvae behavioral assay, KK-235 was found to only partially block the inverted photomotor response (PMR) and to weakly reduce swimming behavior, whereas the high-efficacy GABAergic steroid (3α,5α,17ß)-3-hydroxyandrostane-17-carbonitrile (ACN) fully blocked PMR and spontaneous swimming. Coapplication of KK-235 reduced the potentiating effect of ACN in an electrophysiological assay and dampened its sedative effect in behavioral experiments. We propose that low-efficacy GABAergic potentiators may be useful as sedatives with limited action.

Synthetic routes to trifluoromethylphenyl diazirine photolabeling reagents containing an alkyne substituent (TPDYNE) for chemical biology applications.

The trifluoromethylphenyl diazirine (TPD) group is widely used in photoaffinity labeling studies. The TPDYNE group (TPD with an additional alkyne substituent on the phenyl ring) enables the use of click chemistry in conjunction with photoaffinity labeling and expands the utility of the TPD group. New methods for preparing previously known as well as new TPDYNE reagents are reported. Additional methods for preparation of a TPDYNE precursor from which the TPDYNE group can be generated once the precursor is attached to the molecule of interest are also described. Procedures for attaching the TPDYNE or TPDYNE precursor to carboxyl, amino, hydroxyl and alkyne groups are demonstrated using steroids as examples.

Water-Soluble Polyamide Acid Binder with Fast Li+ Transfer Kinetics for Silicon Suboxide Anodes in Lithium-Ion Batteries.

Silicon suboxide (SiOx) anodes have attracted considerable attention owing to their excellent cycling performance and rate capability compared to silicon (Si) anodes. However, SiOx anodes suffer from high volume expansion similar to Si anodes, which has been a challenge in developing suitable commercial binders. In this study, a water-soluble polyamide acid (WS-PAA) binder with ionic bonds was synthesized. The amide bonds inherent in the WS-PAA binder form a stable hydrogen bond with the SiOx anode and provide sufficient mechanical strength for the prepared electrodes. In addition, the ionic bonds introduced by triethylamine (TEA) induce water solubility and new Li+ transport channels to the binder, achieving enhanced electrochemical properties for the resulting SiOx electrodes, such as cycling and rate capability. The SiOx anode with the WS-PAA binder exhibited a high initial capacity of 1004.7 mAh·g-1 at a current density of 0.8 A·g-1 and a capacity retention of 84.9% after 200 cycles. Therefore, WS-PAA is a promising binder for SiOx anodes compared with CMC and SA.

Continuous supercritical water oxidation treatment of oil-based drill cuttings using municipal sewage sludge as diluent.

Oil-based drill cuttings (OBDC) is a characteristic hazardous waste that is generated in oil and gas exploration. In this study, two typical OBDCs from shale gas fields were treated in a continuous supercritical water oxidation (SCWO) for the first time. Because both heat value and ash content (AC) in the OBDCs were well beyond the capacity of continuous operation, municipal sewage sludge (MSS) was innovatively adapted as the diluent. A mixed sludge with OBDC addition levels of 10%, 20%, and 30% was tested using a novel SCWO reactor. Mean residence times of reactants in different reaction zones were specifically calculated. Results indicated the organic carbon removal efficiency could reach up to 98.44%. Eight detected heavy metals were found to be almost completely removed into solid products, and the concentrations in liquid products were all below the discharge limits. It was also found that the SCWO reactor exhibited good anti-plugging and anti-corrosion performance. The AC in the feedstock was up to 28.58%. To the best of our knowledge, this has, hitherto, not been achieved in a continuous SCWO operation. This study provides a new approach for harmlessly and completely degrading OBDC, and is also helpful for the industrialization of SCWO technology.

Static decontamination of oil-based drill cuttings with pressurized hot water using response surface methodology.

Separating organic pollutants from oil-based drill cuttings (OBDC) is the current trend for its safe disposal. In this study, pressurized hot water extraction (PHWE) was adapted to decontaminate OBDC for the first time. Two typical OBDC samples, i.e., diesel-based drill cuttings (OBDC-A) and white oil-based drill cuttings (OBDC-B), were statically extracted in a homemade batch autoclave. Response surface methodology (RSM) with a central composite design (CCD) was applied to investigate the effects and interactive effects of three independent operating parameters (temperature, extraction time, and water volume) and to ultimately optimize the PHWE process. The results suggested that temperature is the dominant parameter, followed by water volume and extraction time. Interactive effects among the three parameters are present in the PHWE of OBDC-A but absent in the PHWE of OBDC-B. The suitable conditions for the effective PHWE of OBDC-A were found to be a temperature of 284-300 °C, water volume of 15-35 ml, and extraction time of 20-60 min. The corresponding conditions were 237-300 °C, 15-35 ml, and 20-60 min for the PHWE of OBDC-B. These different phenomena are caused by the different characteristics of the two OBDC samples. All of the polynomial models obtained from the RSM experiments are very valid and can adequately describe the relationship among the three independent operating parameters and responses. The experimental results also confirmed that PHWE is a more efficient separation technique for decontaminating OBDC than single organic solvent extraction or low-temperature thermal desorption because PHWE integrates the advantages of both these processes.

A force-based mechanistic model for describing activated sludge settling process.

Sludge settling as the last step in the biological wastewater treatment process substantially affects the system performance, and thus the design and control optimization of the sludge settling process has been frequently investigated with mathematical modeling tools. So far, these models are developed on the basis of the solid flux theory with numerous parameters and complicated boundary conditions, and their prediction results are often unsatisfactory. In this work, a new force-based mechanical model with five parameters was developed, in which five forces were adopted and Newton's law, rather than the flux theory, was used to describe the sludge settling process. In such a model, the phase interactions were taken into account. New functions of hydrodynamic drag, solids pressure and shear stress were developed. Model validation results demonstrate that both batch and continuous sludge settling processes could be accurately described by this model. The predictions of this model were more accurate than those of flux theory-based models, suggesting its advantages in understanding sludge settling behaviors. In addition, this mechanistic model needed to input 5 parameters and set 1 boundary condition only, and could be directly executed by commercial computational fluid dynamics software. Thus, this force-based model provides a more convenient and useful tool to improve the activated sludge settling design and operation optimization.

Supercritical water oxidation of oil-based drill cuttings.

Oil-based drill cuttings (OBDC) are a typical hazardous solid waste that arises from drilling operations in oil and gas fields. The supercritical water oxidation (SCWO) of OBDC was comprehensively investigated in a batch reactor under the conditions of various oxygen coefficients (OC, 1.5-3.5), temperatures (T, 400-500°C) and reaction times (t, 0.5-10min). Preheating experiments indicated that most of the organic compounds in the initial OBDC sample were distributed within gaseous, oil, aqueous and solid phases, with no more than 9.8% of organic compounds converted into inorganic carbon. All tested variables, i.e., OC, T and t, positively affect the transformation of carbon compounds from the oil and solid phases to the aqueous phase and, ultimately, to CO2. Carbon monoxide is the primary stable intermediate. The total organic carbon (TOC) removal efficiency can reach up to 89.2% within 10min at 500°C. Analysis of the reaction pathways suggests both homogeneous and heterogeneous reactions exist in the reactor. The homogeneous reaction is a typical SCWO reaction that is governed by a free radical mechanism, and the heterogeneous reaction is dominated by mass transfer. The information obtained in this study is useful for further investigation and development of hydrothermal treatment procedures for OBDC.

Mathematical modeling of autotrophic denitrification (AD) process with sulphide as electron donor.

Autotrophic denitrification (AD) plays a critical role in nitrate removal from organic carbon-deficient wastewaters with a high level of nitrogen oxides. However, the AD process is not included in the current denitrification models, which limits the application of AD technology for wastewater treatment. In this work, a kinetic model for AD process involved 4 processes and 5 components with 9 parameters is established to describe the sulphide biooxidation and nitrite removal process. In this model, 4 oxidation-reduction reactions using sulphide as electronic donor in the AD process are taken into account. The model parameters are optimized by fitting data from the experiments with different combinations of sulphide, sulphur, sulphate, nitrate and nitrite at various concentrations. Model calibration and validation results demonstrate that the developed model is able to reasonably describe the removal rates of nitrate, nitrite, sulphide and sulphur in the AD process. The model simulation results also show that the sulphur term (η(S)) in the kinetic equations of nitrate, nitrite, sulphur and sulphate remains constant, rather than being controlled by its own concentration. Furthermore, with this model the products of sulphide biooxidation in the AD process, sulphur and sulphate, and their concentrations can be accurately predicted. Therefore, this model provides a strategy to control the sulphate concentration below the discharge limits or recover sulphur as the main end product from sulphide biooxidation.

CRISPR/Cas9 produces anti-hepatitis B virus effect in hepatoma cells and transgenic mouse.

Chronic infection of hepatitis B virus (HBV) is at risk of liver cirrhosis and hepatocellular carcinoma and remains one of the major public health problems worldwide. It is a major barrier of persistence HBV cccDNA under current antiviral therapy as novel strategies of disrupting HBV cccDNA is pressing. The (CRISPR)/Cas9 system is presently emerging in gene editing and we also apply it for targeting and deleting the conserved regions of HBV genome. Two homologous sequences of HBV S and X genes were carried with CRISPR/Cas9 endonuclease to build pCas9 constructs, which may mediate anti-HBV effects of in vitro and in vivo systems in this study. The results showed the better anti-HBV productions by pCas9-2 and without significant differences in between Huh7 and HepG2 cells. CRISPR/Cas9 direct cleavage and mutagenesis were further analyzed of in vitro system. In the M-TgHBV mouse model of HBV, injection of pCas9 constructs by hydrodynamics decreased HBsAg of sera and liver HBcAg. In conclusion, this designed CRISPR/Cas9 system can induce anti-HBV effects and potentially consider as a novel therapeutic agent against chronic HBV infection.

[Physical-chemical properties and structure elucidation of abPS isolated from the root of Achyranthes bidentata].

AIM: To study the physicochemical properties and the structure of Achyranthes bidentata polysaccharide (AbPS). METHODS: AbPS was isolated from the roots of Achyranthes bidentata Bl., and purified by gel filtration chromatography. The distribution of the molecular weight of AbPS was determined by ESI-MS. The structure of AbPS was deduced by methylation analysis, reductive-cleavage and 13CNMR spectroscopy. RESULTS: AbPS was shown to compose of fructose residues and glucose residues and the molar ratio was 8:1. AbPS contain 2,1-linked fructose residue, 2,1-linked fructose residue, 1,2,6-linked fructose residue, terminal fructose residue and terminal glucose residue. CONCLUSION: AbPS is a fructan and belong to graminan.

A detailed kinetic model for the hydrothermal decomposition process of sewage sludge.

A detailed kinetic model for the hydrothermal decomposition (HTD) of sewage sludge was developed based on an explicit reaction scheme considering exact intermediates including protein, saccharide, NH4(+)-N and acetic acid. The parameters were estimated by a series of kinetic data at a temperature range of 180-300°C. This modeling framework is capable of revealing stoichiometric relationships between different components by determining the conversion coefficients and identifying the reaction behaviors by determining rate constants and activation energies. The modeling work shows that protein and saccharide are the primary intermediates in the initial stage of HTD resulting from the fast reduction of biomass. The oxidation processes of macromolecular products to acetic acid are highly dependent on reaction temperature and dramatically restrained when temperature is below 220°C. Overall, this detailed model is meaningful for process simulation and kinetic analysis.