Dehydration of sludge using the polyethylene glycol solution dialysis method and the mechanism of dehydration.

This study was undertaken to develops a new sludge dewatering technology based on polyethylene glycol solution dialysis. This method significantly reduced the final water content of sludge when compared to conventional dewatering methods. It was found that when the osmotic pressure difference between the polyethylene glycol solution and the sludge reached 8 MPa, the moisture content in the sludge was reduced to 28.6%, facilitating deep dehydration. To further improve the dehydration effect and explore the technical feasibility of dialysis dehydration, a dehydration experiment was designed using the polyethylene glycol solution dialysis method combined with external pressure. By applying external pressure to the dialysis membranes, the particles in the sludge were compacted, which reduced the internal voids of the sludge and propelled continuous water discharge. The results demonstrated that the dehydration effect was significantly improved when compared to single dialysis. A scanning electron microscope (SEM) was used to observe and quantitatively analyze the microstructure of the sludge before and after dehydration and to compare the variations in sludge microstructure throughout the dehydration process. The relationships between the sludge moisture content and the porosity and pore equivalent diameter were obtained. This demonstrated the effectiveness of the dewatering experiment using sludge dialysis combined with external pressure. This study also investigates the dehydration mechanism of this method during the sludge dehydration process. This study provides a novel solution for sludge volume reduction that can be applied to sewage treatment in the future.

[Changes in Th17 and CD4+CD25+ Treg cells and their significance among children with hand, foot and mouth disease].

OBJECTIVE: To investigate the changes in peripheral blood Th17 and CD4(+)CD25(+) regulatory T (Treg) cells and their significance among children with hand, foot and mouth disease (HFMD). METHODS: Eighty-nine children with HFMD, including 55 cases of common HFMD and 34 cases of severe HFMD, were included in the study; and 30 healthy children were selected as the control group. The percentages of Th17 and CD4(+)CD25(+) Treg cells in CD4(+) T cells in peripheral blood were determined by flow cytometry. The expression levels of interleukin (IL)-10, transforming growth factor-ß (TGF-ß), and IL-17 were measured by enzyme-linked immunosorbent assay. RESULTS: Compared with the control group, the cases of common HFMD and severe HFMD had significantly increased levels of Th17 cells and IL-17 (P<0.05) but significantly decreased levels of CD4(+)CD25(+) Treg cells, IL-10, and TGF-ß (P<0.05). The severity of the HFMD was positively correlated with the levels of Th17 cells and IL-17 in peripheral blood but negatively correlated with the levels of CD4(+)CD25(+) Treg cells, IL-10, and TGF-ß. CONCLUSIONS: Children with HFMD have increased response of Th17 cells but decreased response of CD4(+)CD25(+) Treg cells in peripheral blood. Th17/CD4(+)CD25(+) Treg cell imbalance may play an important role in the pathogenesis of HFMD.

In vitro and in vivo evaluation of a modified porcine acellular dermal matrix for soft tissue augmentation.

OBJECTIVES: To evaluate the effects of a modified porcine acellular dermal matrix (P-ADM), subepithelial connective tissue graft (SCTG) and other commercial bovine acellular dermal matrix membrane materials (B-ADM) on gingival soft tissue augmentation in the oral esthetic zone. MATERIAL AND METHODS: The characteristics of P-ADM were observed by scanning electron microscope (SEM), Hematoxylin and eosin (H&E) and Masson's trichrome staining (Masson staining). The biocompatibility of P-ADM was verified by CCK8, phalloidin and living/dead cell staining. Beagle dog models were constructed and the thickness of gingiva was analyzed by the intraoral scanner. The morphology was observed by H&E and Masson staining. RESULTS: Scanning electron microscopy, H&E and Masson staining showed that the P-ADM was mainly composed of collagen fibers, with no component of nuclear. The results of CCK8, phalloidin and living/dead cell staining indicated that the P-ADM had good cytocompatibility and no cytotoxicity. Human gingival fibroblasts were able to adhere and stretch on the surface of the material with pseudopodia. The SCTG group outperformed the B-ADM and P-ADM groups in terms of effectiveness, according to the analysis of digital oral scanning data at various time points following incremental soft tissue surgery. Compared with the B-ADM group, the effect of soft tissue increment was better in the P-ADM group. CONCLUSIONS: P-ADM, as a biocompatible biomaterial, can be used as an alternative biomaterial for oral soft tissue thickening. However, the results of this study need to be verified by more clinical trials.

Ultravilolet-radiation-induced graft polymerization of acrylamide onto the melt-blown polypropylene filter element by dynamic method.

By dynamic method under UV irradiation, commercial melt-blown polypropylene (PPMB) filter element was modified with acrylamide (AAm) using benzophenone (BP) as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition: CBP=0.06 mol/L, CAAm=2.0 mol/L, irradiation time: 80 min, temperature: 600 degrees C. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery (approximately 70%) after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.

Flexible conductive polypyrrole nanocomposite membranes based on bacterial cellulose with amphiphobicity.

Flexible conductive polypyrrole nanocomposite membranes based on bacterial cellulose (BC) with amphiphobicity have been successfully prepared through in situ chemical synthesis and then infiltrated with polysiloxane solution. The results suggested that polypyrrole (PPy) nanoparticles deposited on the surface of BC formed a continuous core-shell structure by taking along the BC template. After modification with polysiloxane, the surface characteristics of the conductive BC membranes changed from highly hydrophilic to hydrophobic. The AFM images revealed that the roughness of samples after polysiloxane treatment increased along with the increase of pyrrole concentration. The contact angles (CAs) data revealed that the highest water contact angle and highest oil contact angle are 160.3° and 136.7°, respectively. The conductivity of the amphiphobic membranes with excellent flexibility reached 0.32 S/cm and demonstrated a good electromagnetic shielding effectiveness with an SE of 15 dB which could be applied in electromagnetic shielding materials with self-cleaning properties. It opened a new field of potential applications of BC materials.

Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation.

Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe3O4 nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe3O4 nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit.