Easily scale 3D conductive gradient fiber membrane for contaminants removal and fouling mitigation under electrochemical assistance

An electrochemical membrane filtration system provides an innovative approach to enhance contaminant removal and mitigate membrane fouling. There is an urgent need to develop portable, versatile, and efficient electrochemical membranes for affordable wastewater treatment. Here, a 3D conductive gradient fiber membrane (CC/PVDF) with a gradient porous structure was prepared using a two-step phase inversion method. Methyl orange (MO) was utilized as model organic substance to investigate the electrochemical performance of the CC/PVDF membrane. At applied potentials of +2 V, +3 V, -2 V and -3 V, the removal efficiency of MO was 5.1, 5.3, 4.8, and 5.1 times higher than at 0 V. A dramatic flux loss of 35.02% occurred on the membrane without electrochemistry, interestingly, whereas the flux losses were only 23.59%-10.24% in the applied potential after 30 min of filtration, which were approximately 1.18, 1.28, 1.29 and 1.38 times as high as that without electrochemistry, respectively. The enhanced removal and anti-fouling performances of the membranes were attributed to the functions of electrochemical degradation, electrostatic repulsion, and electrically enhanced wettability. Electrochemical generation of Hydrogen peroxide, along with HO• radicals, was detected and direct electron transfer and HO• were proved to be the dominant oxidants responsible for MO degradation. The intermediate oxidation products were identified by mass spectrometry, and an electrochemical degradation pathway of MO was proposed based on bond-breaking oxidation, ring-opening reactions, and complete oxidation. All the findings emphasize that the ECMF system possesses superior efficiency and creative potential for water purification applications.

Robust self-cleaning membrane with superhydrophilicity and underwater superoleophobicity for oil-in-water separation

The discharge of oily wastewater has increased dramatically and will bring serious environmental problems. In this work, a self-cleaning and anti-fouling g-C₃N₄/TiO₂/PVDF composite membrane was fabricated via the layer-by-layer approach. The surface of as-prepared composite membrane displayed a superhydrophilic and underwater superoleophobic behavior under irradiation with visible light. Also, upon irradiation with visible light, the fabricated g-C₃N₄/TiO₂/PVDF composite membrane displayed enhanced permeation flux and improved oil removal efficiency as a result of the generation of hydroxyl free radicals during the photocatalytic filtration process. Significantly, irradiation with visible light remarkably improved reusability of the composite membrane by initiating photocatalytic decomposition of deposited oil foulants, which enabled removal of over 99.75% of oils, thus reaching a nearly 100% flux recovery ratio. Furthermore, the g-C₃N₄/TiO₂/PVDF composite membrane exhibited great anti-fouling behavior in photocatalysis-assisted filtration. The mechanistic study revealed that underwater superhydrophobicity and the generation of free hydroxyl radicals jointly contributed to membrane anti-fouling. The greatest advantages of this g-C₃N₄/TiO₂/PVDF composite membrane are that not only does it degrades the oil pollutants, but it also makes the membrane less vulnerable to fouling.

Establishing a high-performance anti-fouling PEI-ZIF-PAA membrane with improved Lewis acid-base interactions and hydrophilicity

Membrane fouling and the trade-off between membrane permeability and selectivity restrict the potential applications of membrane filtration for water treatment. ZIF-8 was found having great permeability and antibiofouling performance, but with issue on particle aggregation makes it difficult to achieve high ZIFs loading and fabricate a defect-free molecular sieving membrane in previous research. In this study, we formed a scalable antibiofouling surface with improved permeability and fouling resistance on a PEI-ZIF-PAA membrane using a layer-by-layer assembly technique. The synergistic effects of being sandwiched between two different polyelectrolyte layers with opposite charges endowed the ZIF nanoparticles with improved stability and scalability for membrane modification. The PEI-ZIF-PAA membrane exhibited a satisfactory water flux of 120.78 LMH, which was 46.97% higher than that of the pristine PES membrane. The normalized water flux loss was serious in the absence of ZIF-8, and the flux increased with the ZIF-8 concentration. Antifouling tests suggested that the PEI-ZIF-PAA membrane possessed good antifouling performance due to the much higher surface hydrophilicity and positive Lewis acid-base interactions with foulants. The HA rejection increased with the ZIF-8 concentration and reached a maximum of 92.1% in the presence of 1.00% (w/v) ZIF-8. The membrane regeneration was tested under physical and chemical cleaning with flux recovery rates of about 85% and 95%. XDLVO analysis showed that the total interaction energy between HA and the PEI-ZIF-8-PAA membrane was 26.45 mJ/m², and the superior antifouling performance was mainly attributed to Lewis acid-base interactions. This study indicates that ZIF-8 nanocrystals are promising materials for fabricating novel membranes for sewage treatment.

Forward osmosis membranes for high-efficiency desalination with Nano-MoS2 composite substrates

Attractive membranes are critical for improving efficiencies of forward osmosis (FO) desalination process. In this study, a novel FO-PES-MoS₂ thin film composite (TFC) membrane was assembled using the phase transfer method through merging MoS₂ nanosheets into substrate casting solution. A sequence of characterization techniques was applied to test microstructures and physicochemical properties of the membranes and modification mechanisms based on MoS₂ concentrations. Desalination efficiencies of the fabricated membranes were assessed by three NaCl draw solutions. Compared to the blank membrane, the MoS₂-contained membranes had a thinner active layer, more upright and open pore structure, higher porosity, and lower surface roughness. 1 wt% MoS₂ content was the optimal modification condition, and water flux increased by 35.01% under this condition. Simultaneously, reverse salt flux of the FO-PES-1-MoS₂ membrane declined by 29.15% under 1 M NaCl draw solution, indicating increased salt ion rejection performance of the modified membranes. Moreover, J_s/J_v ratio indicated that MoS₂ nanosheets helped stabilize the desalination performance of the membranes. This study demonstrated that the novel FO-PES-MoS₂ TFC membranes possessed improved performances and showed promising properties for saline water desalination.

[Risk factors for short-term outcome of patients with HBV-related acute-on-chronic liver failure]

OBJECTIVE

To investigate the risk factors for the short-term outcome of patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF), and to establish a risk model for predicting the short-term outcome of these patients.

METHODS

A total of 338 patients with HBV-related ACLF who were admitted to 30 Lod hospital of PLA hospital from January 2010 to January 2014 were enrolled, and a prospective clinical follow-up was performed for them. Multivariate logistic regression was used to determine the risk factors for short-term (12 weeks) outcome, the predictive model with logistic regression equation was established, and the predictive value of this model was evaluated.

RESULTS

The multivariate logistic regression analysis showed that age, a family history of hepatitis B, hepatic encephalopathy (HE), hepatorenal syndrome (HRS), white blood cell (WBC), platelet (PLT), international normalized ratio (INR), total bilirubin (TBil), total bile acid (TBA), creatinine, Na, HBV DNA, and HBeAg were the independent risk factors for the short-term outcome of these patients. Logistic(p) = -4.466 + 1.192 age + 1.631 family history of hepatitis B + 1.091 HE + 1.631 HRS + 1.208 WBC -1.487 PLT + 1.092 INR + 1.446 TBil + 1.608 TBA -1.101 CHE + 1.279 CRE -1.713 Na + 1.032 HBV DNA + 0.833 HBeAg. The area under the receiver operating characteristic curve of the model for the prediction of short-term outcome was 0.930, the cut-off value was 3.16, the sensitivity was 0.860, and the specificity was 0.871. With the increasing scores of the equation, the mortality of patients tended to increase gradually.

CONCLUSION

Age, a family history of hepatitis B, HE, HRS, WBC, PLT, INR, TBil, TBA, CHE, CRE, Na, HBV DNA, and HBeAg are the independent risk factors for the short-term outcome of patients with HBV-related ACLF. The model for predicting short-term outcome established on the basis of independent risk factors has a better clinical value in guiding clinical therapy.

Age-related changes in kallikreins-kinins system in rat corpus cavernosum

Many factors, such as nitric oxide synthase, androgen and growth factors, can regulate the tone of corpus cavernosum (CC) smooth muscle with an age-related tendency. It has been shown that the active metabolites of kallikreins-kinins system (KKS), including bradykinin, Lys-BK and Met-Lys-BK, can also relax the CC smooth muscle significantly in vitro. Our aim was to evaluate the specific association between KKS and age in rat CC. CC and thoracic aorta were isolated from rats at postnatal weeks (PW) of 2, 8, 12, 20, 30, 40 and 60, respectively. Tissue kallikrein-I (KLKI) and kinin B2 receptor (B2R) mRNA in CC and thoracic aorta were detected by real-time polymerase chain reaction (PCR). Protein expression of KLKI and B2R were determined with immunofluorescence in situ and Western blot. Real-time PCR, immunofluorescence in situ and Western blot all demonstrated that the age-related changes in expression of KLKI were similar between the CC and thoracic aorta. It significantly increased with age from PW2 to PW30, reached the peak at PW30 and then declined gradually. However, there was no statistically significant difference among PW30, PW40 and PW60. Similarly, the expression of B2R increased gradually with age reached and remained at the peak during adult stages and no significant differences were found among PW20, PW30 and PW40; then, it decreased significantly at PW60. The changes in the expression of B2R in CC and age-matched aorta were similar except that it was significantly less than that in the aorta at PW60. The expression of KLKI and B2R changed in an age-dependent pattern in rat CC and have a tendency to decline during ageing, which is of the same tendency as reported for erection capacity in ageing males and suggests why ageing is an independent predictor of ED, to some extent.

Electron crystallographic image-processing investigation and superstructure determination for (Pb0.5Sr0.3Cu0.2)Sr2(Ca0.6Sr0.4)Cu2Oy

An electron crystallographic image-processing technique based on the combination of high-resolution electron microscopy and electron diffraction has been developed to investigate the commensurate structural modulation in the high-Tc superconductor (Pb0.5Sr0.3Cu0.2)Sr2(Ca0.6Sr0.4)Cu2Oy. After symmetry averaging, a structure image was obtained by image deconvolution at the resolution limited by that of the electron microscope. Then phase extension was employed to enhance the image resolution up to about 1.25 A by means of the electron diffraction data corrected with an empirical method. In the final projected potential map, the occupational and/or positional modulation is clearly observed for all atoms, including oxygen. The key points of determining superstructures by the technique are studied and discussed.

[Role of afferent renal nerves in 2K2C Goldblatt hypertension]

In order to study the role of afferent renal nerves in 2K2C Goldblatt hypertension, the renal afferent nerves were selectively lesioned by bilateral T9-L2 spinal dorsal rhizotomy before clipping (internal diameter, 0.3 mm) of birenal arteries. Systolic blood pressure of the rat was measured by tail-cuff method. Concentrations of catecholamines, Ang II, and aldosterone were determined respectively by HPLC-EC and RIA, and vascular structural changes were measured by blood vessel micro-image analysis system coupled with a computer. The results showed that the concentrations of NE and E in medulla oblongata, adrenal gland and plasma, and of plasma Ang II and aldosterone as well as body weight of the rat were all significantly increased. The heart coefficient (heart wt/body wt), the media thickness, and the media thickness/lumen diameter in superior mesenteric arteries were also increased in 2K2C hypertensive rats (clipping, 6 wk) as compared with those in control rats. Bilateral rhizotomy delayed development of 2K2C hypertension and prevented above-mentioned vascular structural changes, the NE and E concentrations of medulla oblongata, adrenal gland and plasma were all decreased, hypothalamic NE and E were increased, and plasma Ang II level was not significantly changed. These results suggest that afferent renal nerves may play a partial role in the development of hypertension in 2K2C rats by activating sympathetic nervous system as a result of affecting metabolic activities of brain catecholaminergic neurons, and that high-plasma Ang II and aldosterone as well as heart hypertrophy and proliferation of vascular smooth muscle cells may also participate in the pathogenesis of hypertension in 2K2C rats.