Simultaneous enhancement of nitrate removal flux and methane utilization efficiency in MBfR for aerobic methane oxidation coupled to denitrification by using an innovative scalable double-layer membrane.

Endevours on the enhancement of nitrate removal efficiency during methane oxidation coupled with denitrification (AME-D) has always overlooked the role of membrane employed. It would be highly beneficial to enrich the biomass content and to manage biofilm on the membrane, in the utilization of methane and denitrification. In this study, an innovative and scalable double-layer membrane (DLM) was designed and prepared for a membrane biofilm reactor (MBfR), to simultaneously enhance nitrate removal flux and methane utilization efficiency during aerobic methane oxidation coupled with the denitrification (AME-D) process. The DLM allowed quick bacterial attachment and biomass accumulation for biofilm growth, which would be then self-regulated for well distribution of functional microbes on/within the DLM. Upon a high biofilm density of over 70 g-VSS m-2 achieved on the DLM, the methane utilization efficiency of the MBfR was enhanced significantly to over 1.3 times than the control MBfR with conventional polypropylene membrane. The MBfR employed DLM also demonstrated the maximum nitrate removal flux of 740 mg-NO3--N m-2 d-1 that was approximately 1.64 times of that in control MBfR at continuous-mode operation. This DLM indeed favored the enrichment of Type II aerobic methanotrophs of Methylocystaceae, and methanol-utilization denitrifiers of Rhodocyclaceae that preferentially utilize methanol as the cross-feeding intermediates to promote the methane utilization efficiency, and thus to enhance the nitrate removal flux. These results raised from new designed DLM confirmed the importance of membrane surface properties on the effectiveness of MBfR, and offered great potential to address challenging problems of MBfRs during engineering application.

Fabrication of a double-layer membrane cathode based on modified carbon nanotubes for the sequential electro-Fenton oxidation of p-nitrophenol.

To improve the electrocatalytic efficiency of the cathode and provide a wider pH range in the electro-Fenton process, N-doped multi-walled carbon nanotubes (NCNTs) and ferrous ion complexed with carboxylated carbon nanotubes (CNT-COOFe2+) were used to fabricate the diffusion layer and catalyst layer of a membrane cathode, respectively. The morphology, structure, and composition of CNT-COOFe2+ were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The oxygen reduction performance of NCNT was evaluated using cyclic voltammetry (CV) and the rotating disk electrode technique (RDE). In addition, a potential application of the cathode in sequential electro-Fenton degradation of p-nitrophenol (p-NP) was investigated. The results revealed that iron was successfully doped on the carboxylated carbon nanotubes in ionic complexation form and the content of iron atoms in CNT-COOFe2+ was 2.65%. Furthermore, the defects on the tube walls provided more reactive sites for the electro-Fenton process. A combination of CV and RDE data indicated that NCNT had better electrocatalytic H2O2 generation activity with a more positive onset potential and higher cathodic peak current response than CNT. A p-NP removal rate of 96.04% was achieved within 120 min, and a mineralization efficiency of 80.26% was obtained at 180 min in the sequential electro-Fenton process at a cathodic potential of - 0.7 V vs SCE and neutral pH. The activity of the used cathode was restored simply through electro-reduction at - 1.0 V vs SCE, and a p-NP removal rate of more than 70% was obtained at 60 min after six regeneration cycles.

Effective delivery of mitomycin-C and meloxicam by double-layer electrospun membranes for the prevention of epidural adhesions.

Epidural adhesion between the spinal dura and the surrounding fibrous tissue often occurs post-laminectomy, resulting in clinical symptoms such as nerve compression and severe pain. In this study, we report a drug-loaded double-layered electrospun nanofiber membrane to prevent the occurrence of epidural adhesion. The nanofibers in both layers are made of a mixture of polycaprolactone (PCL) and chitosan (CS) but at different weight ratios. The bottom layer contacting to the spinal dura is loaded with meloxicam (MX) to prevent inflammation. The top layer that contacts to the fibrous tissue is doped with mitomycin-C (MMC) to inhibit the synthesis of DNA and collagen. The two types of drugs are released from the double-layered membrane within about 12 days. Meanwhile, the membrane can inhibit fibroblasts proliferation in vitro while show no cytotoxicity. In a rabbit laminectomy model, the double-layered membrane can effectively prevent the epidural adhesion formation based on the adhesion scores, histological and biochemical evaluations. The combination release of MX and MMC can signally reduce the inflammation reaction and collagen I/III expression relative to the case with the membranes loaded with only either one type of the drugs. This approach offers new progresses in constructing dual drug delivery system and provides innovative barrier strategy in inhibiting epidural adhesion post-laminectomy.

Optimization of Formulation of Erhuangsan Bletillae Rhizoma Gelatin Sustained Release Double-layer Membrane by Central Composite Design-response Surface Methodology / 中国实验方剂学杂志

Objective: With Bletillae Rhizoma gelatin as the main film-forming materials, Erhuangsan was developed into a sustained-release double-layer membrane for vagina. Method: Taking hydroxypropyl methyl cellulose(HPMC) and Bletillae Rhizoma gelatin as the film-forming materials of Coptidis Rhizoma-Alumen membrane layer, sodium carboxymethyl cellulose(CMC-Na) and Bletillae Rhizoma gelatin as the film-forming materials of Catechu membrane layer, glycerol as plasticizer, Erhuangsan Bletillae Rhizoma gelatin sustained release double-layer membrane was prepared.Central composite design-response surface methodology was used to optimize formulation of this preparation with appearance quality score, adhesion force and in vitro cumulative release as indexes. Result: Optimum formulation of Catechu membrane layer was 1.61% of CMC-Na, 3.81% of Bletillae Rhizoma gelatin and 8.49% of glycerol;optimum formulation of Coptidis Rhizoma-Alumen membrane layer was 1.15% of HPMC, 3.41% of Bletillae Rhizoma gelatin and 10.02% of glycerol. Conclusion: The optimized formulation is stable and feasible.Erhuangsan Bletillae Rhizoma gelatin sustained release double-layer membrane has characteristics of advanced dosage form and convenient use, providing a feasible modern Chinese medicine preparation for treatment of cervical cancer, and accumulating data for the research of Chinese medicine film agent.