Heterotrophic nitrification-aerobic denitrification performance of a novel strain, Pseudomonas sp. B-1, isolated from membrane aerated biofilm reactor.

A heterotrophic nitrification-aerobic denitrification (HN-AD) strain isolated from membrane aerated biofilm reactor (MABR) was identified as Pseudomonas sp. B-1, which could effectively utilize multiple nitrogen sources and preferentially consume NH4-N. The maximum degradation efficiencies of NO3-N, NO2-N and NH4-N were 98.04%, 94.84% and 95.74%, respectively. The optimal incubation time, shaking speed, carbon source, pH, temperature and C/N ratio were 60 h, 180 rpm, sodium succinate, 8, 30 °C and 25, respectively. The strain preferred salinity of 1.5% and resisted heavy metals in the order of Mn2+ > Co2+ > Zn2+ > Cu2+. It can be preliminarily speculated from the results of enzyme assay that the strain removed nitrogen via full nitrification-denitrification pathway. The addition of strain into the conventional MABR significantly intensified the HN-AD performance of the reactor. The relative abundance of the functional bacteria including Flavobacterium, Pseudomonas, Paracoccus, Azoarcus and Thauera was obviously increased after the bioaugmentation. Besides, the expression of the HN-AD related genes in the biofilm was also strengthened. Thus, strain B-1 had great application potential in nitrogen removal process.

Start-up and synergistic nitrogen removal of partial nitrification and anoxic/aerobic denitrification in membrane aerated biofilm reactor.

To reduce energy consumption and improve operational stability of traditional biological nitrogen removal (BNR) system, partial nitrification and anoxic/aerobic denitrification were synergistically implemented in membrane aerated biofilm reactor (MABR) by regulating DO and pH. The results indicated that the optimal DO, pH and C/N ratio were 1-2 mg/L, 9.0 and 4-7, respectively. The corresponding average organic removal rate (ORR), total nitrogen removal rate (TNRR) and nitrite accumulation rate (NAR) reached 324 gCOD・m-3・d-1, 48 gN・m-3・d-1 and 77.70%, respectively. Extracellular polymeric substance (EPS) content in biofilm was more abundant than that in inoculated sludge. Multiple aerobic denitrifiers were detected in the biofilm with the relative abundance of 11.19%-22.71%. AQUASIM simulation implied that the distribution and proportion of substrates and bacteria were significantly affected by DO and pH regulation. Overall, this study provided some important insights in the start-up and operation of synergistic nitrogen removal process in BNR system.

Clinical Value of Combined Detection of CK-MB, MYO, cTnI and Plasma NT-proBNP in Diagnosis of Acute Myocardial Infarction.

BACKGROUND: Acute myocardial infarction (AMI) is a serious life-threatening and common heart disease that is based on coronary atherosclerosis. The aim is to study the changes in the level of kinase isoenzyme (CK-MB), myoglobin (MYO), cardiac troponin I (cTnI), and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with acute myocardial infarction (AMI) and the four indicators of joint detection clinical value for diagnosis of AMI. METHODS: Plasma NT-proBNP, CK-MB, MYO, and cTnI were detected by CLIA in 208 AMI patients (AMI group) and 115 non-AMI patients (control group). SPSS 19.0 software was used to analyze the data. RESULTS: The concentrations of CK-MB, MYO, cTnI, and NT-proBNP show significant differences between these two groups. In the AMI group, a significantly positive correlation was found between CK-MB and each of MYO and cTnI (r = 0.537, r = 0.226). Meanwhile, the sensitivity of combined detection has been improved up to 92.79%. CONCLUSIONS: Therefore, these results suggested that detecting CK-MB, MYO, cTnI, and plasma NT-proBNP levels together can significantly contribute to the early diagnosis of AMI. It can also provide diagnostic evidence to clinic and thus lower the mortality of AMI in acute phase.

Bacterial community shift along with the changes in operational conditions in a membrane-aerated biofilm reactor.

Membrane-aerated biofilm reactor (MABR) is a promising wastewater treatment process. Although bacteria inhabiting the MABR biofilm are important in wastewater treatment, the community composition and its correlation with operating conditions were less clear. A laboratory-scale MABR was designed to investigate the shift of bacterial community through a complete operational process by pyrosequencing the bacterial 16S rRNA genes. From around 19,000 sequences, 175 bacterial genera were retrieved, mainly belonging to Betaproteobacteria, Gammaproteobacteria, Alphaproteobacteria, Bacteroidetes, and Actinobacteria. A large number of unclassified bacterial sequences were also detected in the biofilm, suggesting a wide variety of uncharacterized species in MABR. Redundancy analysis (RDA) revealed that influent chemical oxygen demand (COD), NH4-N, and NaHCO3 concentrations could exert distinct influences on the composition of the bacterial community. The influent COD and NaHCO3 concentrations stimulated proliferation of denitrification-related species such as Dokdonella, Azospira, Hydrogenophaga, Rhodocyclaceae, and Thauera, while inhibiting the growth of Acidovorax and Sinobacteraceae. Some denitrifying Thermomonas spp. tended to survive in NH4-N-rich environments, while Flavobacterium preferred to inhabit NH4-N-poor or COD-rich environments. Conversely, the influent NH4-N and NaHCO3, to some extent, appeared to be the growth-promoting factors for nitrifying bacteria. Furthermore, the presence of potential aerobic denitrifiers such as Comamonas, Enterobacter, and Aeromonas indicated that MABR could have the capability of simultaneous aerobic and anoxic denitrification particularly during treatment of low-ammonia nitrogen sewage.

Treatment of volatile organic compounds and other waste gases using membrane biofilm reactors: A review on recent advancements and challenges.

This article provides a comprehensive review of membrane biofilm reactors for waste gas (MBRWG) treatment, focusing on studies conducted since 2000. The first section discusses the membrane materials, structure, and mass transfer mechanism employed in MBRWG. The concept of a partial counter-diffusion biofilm in MBRWG is introduced, with identification of the most metabolically active region. Subsequently, the effectiveness of these biofilm reactors in treating single and mixed pollutants is examined. The phenomenon of membrane fouling in MBRWG is characterized, alongside an analysis of contributory factors. Furthermore, a comparison is made between membrane biofilm reactors and conventional biological treatment technologies, highlighting their respective advantages and disadvantages. It is evident that the treatment of hydrophobic gases and their resistance to volatility warrant further investigation. In addition, the emergence of the smart industry and its integration with other processes have opened up new opportunities for the utilization of MBRWG. Overcoming membrane fouling and developing stable and cost-effective membrane materials are essential factors for successful engineering applications of MBRWG. Moreover, it is worth exploring the mechanisms of co-metabolism in MBRWG and the potential for altering biofilm community structures.

Municipal solid waste leachate treatment by three-stage membrane aeration biofilm reactor system.

A combined process of coagulation pretreatment and three-stage membrane aeration biofilm reactor (MABR) system was successfully applied for the first time to treat actual municipal solid waste leachate (MSWL), which was characterized by high concentrations of toxic hard-to-degrade organics and salinity. The results showed that 9.8%-21.3% of organics could be removed from actual MSWL by coagulation with polymeric aluminum chloride (PAC). Three-stage MABR contributed 95.6% of the chemical oxygen demand (COD) removal, with the influent COD concentration ranging from 6000 to 7000 mg/L. At the same time, the removal efficiencies of total nitrogen (TN) and ammonia (NH4+-N) could reach to 84.3% and 79.9% without the addition of external carbon source, respectively. The nitrifying/denitrifying bacteria were enriched in the biofilm including Thiobacillus, Azoarcus and Methyloversatilis, which supported the MABR with high nitrogen removal efficiency and significantly toxic tolerance. Principal component analysis (PCA) and the Pearson correlation coefficients (r) illustrated that aeration pressure is a crucial operational parameter, exhibiting a strong correlation between the MABR performance and microbial communities. This work demonstrates that MABR is an effective and low-energy option for simultaneous removal of carbon and nitrogen in the treatment of MSWL.

Thermal Conductivity of Polyvinylidene Fluoride Films with a Multi-Scale Framework.

The orientation of amorphous regions in pure polymers has been noted to be critical to the enhancement of thermal conductivity (TC), but the available reports are still rather few. Here, we propose to prepare a polyvinylidene fluoride (PVDF) film with a multi-scale framework by introducing anisotropic amorphous nanophases in the form of cross-planar alignments among the in-planar oriented extended-chain crystals (ECCs) lamellae, which show an enhanced TC of 1.99 Wm-1 K-1 in the through-plane direction (K⟂) and 4.35 Wm-1 K-1 in the in-plane direction (K∥). Structural characterization determination using scanning electron microscopy and high-resolution synchrotron X-ray scattering showed that shrinking the dimension of the amorphous nanophases can effectively reduce entanglement and lead to alignments formation. Moreover, the thermal anisotropy of the amorphous region is quantitatively discussed with the aid of the two-phase model. Superior thermal dissipation performances are intuitively displayed by means of finite element numerical analysis and heat exchanger applications. Moreover, such unique multi-scale architecture also results in significant benefit in the improvement of dimensional stability and thermal stability. This paper provides a reasonable solution for fabricating inexpensive thermal conducting polymer films from the perspective of practical applications.

Steel pickling rinse wastewater treatment by two-stage MABR system: Reactor performance, extracellular polymeric substances (EPS) and microbial community.

A bench-scale two-stage membrane-aerated biofilm reactor (MABR) system was applied to treat steel pickling rinse wastewater with high salinity and refractory organic. The effects of salinity and aeration pressure on the treatment efficiency, extracellular polymeric substances (EPS) characteristics and microbial community structure were studied. The optimal removal efficiencies of COD, NH+ 4-N and TN reached to 62.84%, 99.57% and 51.65%, respectively. Shortcut nitrification was achieved at low aeration, and the salinity less than 4% did not remarkable affect system performance. Colorimetric determination, three-dimensional exaction-emission matrix (3D-EEM) and Fourier transform infrared spectrum (FTIR) were employed to characterize the content and composition of proteins (PN) and polysaccharides (PS) in EPS of the biofilm. The results indicated that PN, not PS, response to changes of environmental conditions played a key role. Moreover, EPS might alleviate intracellular and extracellular osmotic pressure imbalance induced by high salinity, which imparted the biofilm in MABR with prominent salt-tolerant. High-throughput sequencing displayed that nitrifiers (Nitrosomonas, Nitrospira), denitrifiers (Dechloromonas, Hyphomicrobium, Denitromonas, Denitratisoma, Candidatus_Competibacter) and aerobic denitrifiers (Pseudomonas, Thauera) were predominant salt-tolerant bacteria.

In-situ enrichment and application of heterotrophic nitrification-aerobic denitrification bacteria in membrane aerated biofilm reactor.

In order to reduce the resource and energy consumption of traditional biological nitrogen removal (BNR) process, heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria was in situ enriched in membrane aerated biofilm reactor (MABR) by inoculating conventional activated sludge. Contaminants removal performance, EPS composition and microbial community were explored. The results indicated that the average removal efficiency of COD and TN under optimal condition reached 84.13% and 91.54%, respectively, which demonstrated that the reactor possessed excellent contaminants removal capacity. EPS analysis suggested that abundant protein especially tryptophan protein-like substance played a vital role in maintaining the microbial stability of biofilms. Multiple HN-AD genera, mainly Paracoccus, were detected with the highest relative abundance of 54.70%, which confirmed the successful enrichment of the HN-AD bacteria. Conventional nitrifiers and denitrifiers also thrived in biofilm, which demonstrated the synergistic nitrogen removal of multiple microorganisms. This study provided important insights into application of HN-AD bacteria and synergistic nitrogen removal in BNR system.

Ovol1 regulates the growth arrest of embryonic epidermal progenitor cells and represses c-myc transcription.

Transcriptional control plays a key role in regulating epidermal proliferation and differentiation. Although ample information has been obtained on how epidermal homeostasis is controlled in adult skin, less is known about the control of proliferation/differentiation of epidermal stem/progenitor cells in the developing embryo. Ovol1, encoding a zinc finger protein homologous to Drosophila melanogaster Ovo, is expressed in embryonic epidermal progenitor cells that are transiting from proliferation to terminal differentiation. In this study, we demonstrate a function for Ovol1 in interfollicular epidermal development. In its absence, developing epidermis fails to properly restrict the proliferative potential of progenitor cells, and cultured keratinocytes fail to efficiently undergo growth arrest in response to extrinsic growth-inhibitory signals. We present molecular evidence that c-myc expression is up-regulated in Ovol1-deficient suprabasal cells and that Ovol1 represses c-myc transcription by directly binding to its promoter. Collectively, our findings indicate that Ovol1 is required for proliferation exit of committed epidermal progenitor cells and identify c-myc as an Ovol1 target.

Advanced treatment of coal chemical reverse osmosis concentrate with three-stage MABR.

The issue of reverse osmosis concentrate (ROC) has attracted significant attention due to its complex and toxic constituents under high salinity conditions. In this work, a three-stage membrane-aerated biofilm reactor (MABR) system was constructed to treat such wastewater without an external carbon source. The effects of operating conditions including aeration pressure, reflux ratio, temperature and hydraulic retention time on the removal performance of the integrated system were evaluated and optimized. Under the optimal operating parameters, the removal efficiencies of COD, NH4 +-N, NO3 --N, and TN reached 69.36%, 80.95%, 54.55%, and 54.36%, respectively. Three-dimensional fluorescence analysis indicated that humic acid was mostly removed from raw water. Moreover, microbial diversity analysis indicated that the microbial community structure of each reactor could be individually modulated to exert different functions and enhance the system performance. The integrated MABR system exhibits great feasibility and potential for the advanced treatment of coal chemical ROC.

Enhanced carbon and nitrogen removal in an integrated anaerobic/anoxic/aerobic-membrane aerated biofilm reactor system.

A pilot-scale anaerobic/anoxic/aerobic-membrane aerated biofilm reactor (A2/O-MABR) system was constructed to enhance carbon and nitrogen removal. The effects of major operating parameters including the nitrate recycling ratio (R), sludge recycling ratio (r), and aerobic tank dissolved oxygen (DO) concentration on the system performance were investigated. The average removal efficiencies of the chemical oxygen demand (COD), ammonium nitrogen (NH4 +-N), and total nitrogen (TN) were 89.0 ± 3.2%, 98.8 ± 1.3%, and 68.5 ± 4.2%, respectively, and their effluent concentrations were averagely 22.6 ± 7.3, 0.32 ± 0.2, and 13.3 ± 1.2 mg L-1. The suspended sludge and biofilm in aerobic tank facilitated the simultaneous nitrification and denitrification (SND) processes. Indeed, unique biofilm layered structure and abundant microbial community in the biofilm on MABR would enhance nitrogen removal. Compared with the A2/O system, the A2/O-MABR system exhibited higher nitrifying bacteria oxygen uptake rate (OUR) of 58.1 and 54.5 mgO2 per gMLSS per h in suspended sludge and biofilm, respectively, and the lower mixed liquor suspended solid (MLSS) concentration of 1800 mg L-1. Moreover, high-throughput sequencing indicated that putative nitrogen removal bacteria such as Thauera and Paracoccus could be effectively enriched in the biofilm. Since the volume proportions of the anaerobic, anoxic, aerobic and settling tank in the existing A2/O system of the WWTP was not changed, the A2/O-MABR system was simple and practical for the upgrading of A2/O system.

Biodegradation of phenolic compounds in high saline wastewater by biofilms adhering on aerated membranes.

High saline phenolic wastewater is a typical toxic and refractory industrial wastewater. A single membrane-aerated biofilm reactor (MABR) was used to treat wastewater containing phenol, p-nitrophenol and hydroquinone under increasing phenolic loading and salinity conditions. More than 95 % of phenolic compounds were removed, and a removal efficiency of 8.9 g/m2 d for total phenolic (TP) contents was achieved under conditions with 32 g/L of salt and 763 mg/L of influent TP contents. The microbial diversity, structure and function of a biofilm exposed to different conditions were investigated by high-throughput 16S rRNA gene sequencing and metagenomics. Salinity and specific TP loading substantially affected the bacterial community. Gammaproteobacteria, Actinobacteria and Betaproteobacteria contributed more to initial phenolic compound degradation than other classes, with Pseudomonas and Rhodococcus as the main contributing genera. The key phenolic-degrading genes of different metabolic pathways were explored, and their relative abundance was strengthened with increasing phenolic loading and salinity. The diverse cooperation and competition patterns of these microorganisms further promoted the high removal efficiency of multiple phenolic contaminants in the biofilms. These results demonstrate the feasibility of MABR for degrading multiple phenolic compounds in high saline wastewater.

Supersoft symmetry energy encountering non-Newtonian gravity in neutron stars.

Considering the non-Newtonian gravity proposed in grand unification theories, we show that the stability and observed global properties of neutron stars cannot rule out the supersoft nuclear symmetry energies at suprasaturation densities. The degree of possible violation of the inverse-square law of gravity in neutron stars is estimated using an equation of state of neutron-rich nuclear matter consistent with the available terrestrial laboratory data.

Enhanced wastewater treatment with high o-aminophenol concentration by two-stage MABR and its biodegradation mechanism.

A two-stage bench-scale membrane-aerated biofilm reactor (MABR) was developed to treat wastewater containing high o-aminophenol (OAP) content. Long-term process showed that MABR-1 can achieve the removal rates of 17.6 g OAP/m2 d and 29.4 g COD/m2 d. MABR-2 can effectively perform more than 90% TN removal with the addition of external glucose. Pseudomonas and Nitrosomonas were the key functional genera in MABR-1 and MABR-2, respectively. Functional genes related to OAP degradation, including amnA,B,D, dmpC,H, mhpD,E,F, and bphH,I,J, were detected, and the involved enzymes were predicted. The OAP-degrading species and functional contribution analysis indicated that OAP can be metabolized by a single Pseudomonas or by the synergistic effects of bacteria, mainly including Cupriavidus, Thauera, unclassified Sphingomonadaceae, Lysobacter, and Azotobacter or by the cooperation of all the bacteria above. These diversified patterns guaranteed the high efficiency for OAP removal in MABR when treating wastewater with high OAP concentration.

Bicontinuous and cellular structure design of PVDF membranes by using binary solvents for the membrane distillation process.

With excellent permeability as the foremost requirement for membranes used in the membrane distillation (MD) process, the thermally induced phase separation (TIPS) method is a promising approach for preparing porous membranes with a bicontinuous structure, which is identified as the best morphology for permeation. The structure design of membranes prepared by the TIPS process can be strengthened when a binary solvent is introduced in the casting solution. In this work, the determination principles for binary solvent were explicated in detail, and further employed for the selection of binary solvent for the fabrication of polyvinylidene fluoride (PVDF) membrane with different structures. By the TIPS approach, the porous PVDF hollow fiber membranes with cellular structure were generated by g-butyrolactone (GBL)/dioctyl phthalate (DOP) and GBL/dioctyl adipate (DOA) binary solvents, while the membrane with a bicontinuous structure was produced from GBL/dioctyl sebacate (DOS) binary solvent. The phase diagram was used to explain a feasible mechanism for the formation of the porous structures above. When the morphologies and properties of the membranes were characterized and compared, the membrane with a bicontinuous structure rather than a cellular structure was identified as the potential structure for MD processes with much higher tensile strength, narrower pore size distribution, higher MD flux and excellent long-term performance.

Coal chemical reverse osmosis concentrate treatment by membrane-aerated biofilm reactor system.

Coal chemical reverse osmosis concentrate (ROC), which is characterized by high salinity and high organics, remains as a serious environmental problem. In this study, a lab-scale three-stage membrane-aerated biofilm reactor (MABR) system was designed to treat such a ROC. The effects of influent salinity and operating parameters (pH, DO and HRT) on the treatment efficiency were discussed. The removal efficiencies of COD, NH4-N and TN under the optimal operating parameters reached to 81.01%, 92.31% and 70.72%, respectively. Simultaneous nitrification and denitrification (SND) as well as shortcut nitrogen removal were achieved. The salinity less than 3% did not induce significant decrease in treatment efficiency and microbial communities. Moreover, the dominant phyla in biofilms were Proteobacteria and Bacteroidetes. This work demonstrated MABR had great potential in ROC treatment.

Mussel-Inspired and Magnetic Co-functionalization of Hexagonal Boron Nitride in Poly(vinylidene fluoride) Composites Toward Enhanced Thermal and Mechanical Performance for Heat Exchangers.

Thermal-conductive polymer composites have developed to be a hotspot in academic and industrial fields recently. Both efficient heat transport and superior mechanical properties are of critical significance for high-performance thermal-conductive devices. In this paper, magnetic hexagonal boron nitride (mhBN) with excellent interfacial compatibility is successfully synthesized by dopamine and magnetic co-functionalization, and mhBN-poly(vinylidene fluoride) (mhBN-PVDF) composites with a combination of high thermal conductivity and outstanding mechanical property are achieved due to the integration of excellent interfacial interaction and aligned filler architecture into one material's system. The thermal conductivity increases from 0.35 W/(m K) for the 20 wt % pure BN-PVDF to 0.82 W/(m K) after the dopamine modification and further to 1.43 W/(m K) after alignment. The effective medium approximation model demonstrates that the optimization of mhBN orientation and decrease of thermal resistance are two major factors for the enhancement of thermal conductivity. Moreover, the mhBN-PVDF composites also exhibit excellent tensile strength (168.5 MPa at 15 wt % content) and impact strength (20-30 kJ/m2). The significantly enhanced thermal and mechanical properties result in the excellent heat exchange ability and durability in the heat exchange test, which is important for potential application in the heat exchange industry.

Synthesis and characterization of Tamoxifen citrate modified reduced graphene oxide nano sheets for breast cancer therapy.

Theranostic agents are of immense consideration in the current generation nanomedicine. In this study, we have developed a facile approach for the fabrication of Tamoxifen citrate modified nanosized reduced graphene oxide (nano-rGO) with more stability and low cytotoxicity. The prepared nano-rGO sheets were characterized using HR-TEM and AFM imaging techniques. Further, the cytotoxicity was assessed using MTT assay on female BALB/c nude mice MCF-7 cell lines. In addition, by means of continuous-wave near-infrared laser, cancer cells in vivo were significantly ablated because of the photothermal effect stimulated by tamoxifen modified nano-rGO. These results indicated that the prepared tamoxifen modified nano-rGO has the ability to apply in the photothermal therapy of breast cancers. Consequently, further exploration of photothermal therapeutics is desirable for the synthesis of novel nano materials with additional functionalities.