Constructing spherical-beads-on-string structure of electrospun membrane to achieve high vapor flux in membrane distillation.

Hydrophobic membranes with a reentrant-like structure have shown high hydrophobicity and high anti-wetting properties in membrane distillation (MD). Here, PVDF spherical-beads-on-string (SBS) fibers were electrospun on nonwoven fabric and used in the MD process. Such a reentrant-like structure was featured with fine fibers, a low ratio of bead length to bead diameter, and high bead frequency. It was revealed that the SBS-structured membranes exhibited an exceptional capability for vapor flux, due to the formation of a network of more interconnected macropores than that of fibers and fusiform-beads-on-string structures, ensuring unimpeded vapor diffusion. In the desalination of formulated seawater (3.5 wt.% NaCl solution), a vapor flux of 61 ± 3 kg m-2 h-1 with a salt rejection of >99.98 % was achieved at a feed temperature of 60 °C. Furthermore, this SBS structured membrane showed satisfactory seawater desalination performance with a stable flux of 40 kg m-2 h-1 over a 27 h MD process. These findings suggest a viable approach for fabricating SBS-structured membranes that significantly enhance vapor flux in MD for desalination applications. Besides, the hydrophobic membranes with SBS structure can be prepared by single-step electrospinning, and it is facile to scale-up manufacture. This strategy holds promise for advancing the development of high-performance MD membranes tailored for efficient seawater desalination processes.

Ni Single-Atoms Based Memristors with Ultrafast Speed and Ultralong Data Retention.

Memristor with low-power, high density, and scalability fulfills the requirements of the applications of the new computing system beyond Moore's law. However, there are still nonideal device characteristics observed in the memristor to be solved. The important observation is that retention and speed are correlated parameters of memristor with trade off against each other. The delicately modulating distribution and trapping level of defects in electron migration-based memristor is expected to provide a compromise method to address the contradictory issue of improving both switching speed and retention capability. Here, high-performance memristor based on the structure of ITO/Ni single-atoms (NiSAs/N-C)/Polyvinyl pyrrolidone (PVP)/Au is reported. By utilizing well-distributed trapping sites , small tunneling barriers/distance and high charging energy, the memristor with an ultrafast switching speed of 100 ns, ultralong retention capability of 106  s, a low set voltage (Vset ) of ≈0.7 V, a substantial ON/OFF ration of 103 , and low spatial variation in cycle-to-cycle (500 cycles) and device-to-device characteristics (128 devices) is demonstrated. On the premise of preserving the strengths of a fast switching speed, this memristor exhibits ultralong retention capability comparable to the commercialized flash memory. Finally, a memristor ratioed logic-based combinational memristor array to realize the one-bit full adder is further implemented.

Surface-immobilized cross-linked cationic polyelectrolyte enables CO2 reduction with metal cation-free acidic electrolyte.

Electrochemical CO2 reduction in acidic electrolytes is a promising strategy to achieve high utilization efficiency of CO2. Although alkali cations in acidic electrolytes play a vital role in suppressing hydrogen evolution and promoting CO2 reduction, they also cause precipitation of bicarbonate on the gas diffusion electrode (GDE), flooding of electrolyte through the GDE, and drift of the electrolyte pH. In this work, we realize the electroreduction of CO2 in a metal cation-free acidic electrolyte by covering the catalyst with cross-linked poly-diallyldimethylammonium chloride. This polyelectrolyte provides a high density of cationic sites immobilized on the surface of the catalyst, which suppresses the mass transport of H+ and modulates the interfacial field strength. By adopting this strategy, the Faradaic efficiency (FE) of CO reaches 95 ± 3% with the Ag catalyst and the FE of formic acid reaches 76 ± 3% with the In catalyst in a 1.0 pH electrolyte in a flow cell. More importantly, with the metal cation-free acidic electrolyte the amount of electrolyte flooding through the GDE is decreased to 2.5 ± 0.6% of that with alkali cation-containing acidic electrolyte, and the FE of CO maintains above 80% over 36 h of operation at -200 mA·cm-2.

Hydrophobic modification of a PVDF hollow fiber membrane by plasma activation and silane grafting for membrane distillation.

Polyvinylidene fluoride (PVDF) hollow fibers were hydrophobically modified using a simple and scalable method of plasma activation and silane grafting. The effects of plasma gas, applied voltage, activation time, silane type, and concentration were investigated according to the membrane hydrophobicity and direct contact membrane distillation (DCMD) performance. Two kinds of silane were used, including methyl trichloroalkyl silane (MTCS) and 1H,1H,2H,2H-perfluorooctane trichlorosilane silanes (PTCS). The membranes were characterized by techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angle. The contact angle of the pristine membrane was 88°, which increased to 112°-116° after modification. Meanwhile, the pore size and porosity decreased. In DCMD, the maximum rejection reached 99.95% by the MTCS-grafted membrane, while the flux decreased by 35% and 65% for the MTCS- and PTCS-grafted membranes, respectively. Treating humic acid-contained solution, the modified membrane showed steadier water flux and higher salt rejection than the pristine membrane, and 100% flux recovery was achieved by simple water flushing. This two-step method of plasma activation and silane grafting is very simple and effective to improve the hydrophobicity and DCMD performance of PVDF hollow fibers. However, further study on improving the water flux should be carried out.

The role of interlayers in enlarging the flux of GO membranes.

A graphene oxide (GO) membrane can be easily made by filtering a GO solution onto a supporting layer, and such a membrane is effective at adsorbing ions. But low flux and a high work pressure become an obstacle for its application in wastewater treatment. In this study, a positively charged mixture of carbon nanotubes and chitosan (CNTS) served as an interlayer to improve the GO membrane's flux. The three-layer membrane is known as MCG, while one without an interlayer is known as MG. For MCG and MG with the same GO load, the water flux of MCG reaches 2-8 times larger than that of MG. A better water permeability is consistently detected for MCG, with a contact angle descent speed of 3.3°/s, which is significantly faster than that of MG (0.5°/s). The ion rejections of MCG and MG are mostly attributed to GO adsorption, which stay at the same level. The flux varies with GO load, CNTS load and membrane dryness, while the ion rejection is correlated with the GO load. Optimized membrane fabrication conditions are suggested as being a CNTS load of 0.72 g m-2 and a GO load of 0.4 g m-2. A 'gap' mechanism is suggested to explain the interlayer effects. The rougher interlayer surface produces gaps between the GO and CNTS layers, which results in the faster water permeation and higher flux of MCG. These results demonstrate that it is possible to fabricate high flux GO membranes by adding a controlled-roughness interlayer.

Effect of cytokine-induced killer cells combined with dendritic cells on the survival rate and expression of 14-3-3ζ and p-Bad proteins in Lewis lung cancer cell lines.

In the present study, the function and mechanism of cytokine-induced killer cells (CIK) combined with dendritic cells (DC-CIK) were examined in Lewis lung cancer (LLC) cells. Co-culture of CIK dendritic cells (DC) in vitro was used to investigate their proliferation and the antitumor effects on LLC cells. DC and CIK cells were collected from healthy human peripheral blood mononuclear cells and co-cultured as an experimental group, while LLC cells were cultured alone as a control group. Cell morphology was observed by an inverted microscope and an MTT assay was utilized to detect the proliferation of LLC cells. Expression of 14-3-3ζ and p-Bad were measured by western blot analysis. Compared with the control group, treatment of LLC cells with DC-CIK resulted in decreased cell adherence, reduced cell proliferation and abnormal morphological changes. Additionally, DC-CIK treatment of LLC cells resulted in the decreased expression of 14-3-3ζ and p-Bad protein in LLC cells, which may provide important information pertaining to the possible mechanism of DC-CIK-induced antitumor activity against LLC cells. The present study provides a theoretical and experimental basis for the clinical treatment of DC-CIK cell co-culture.

Flexible Fe2 O3 and V2 O5 Nanofibers as Binder-Free Electrodes for High-Performance All-Solid-State Asymmetric Supercapacitors.

Flexible, highly porous Fe2 O3 and V2 O5 nanofibers (NFs) have been synthesized by a facile electrospinning method followed by calcination. They have been directly used as binder-free electrodes for high-performance supercapacitors. These Fe2 O3 and V2 O5 NFs interconnect with one another and construct three-dimensional hierarchical porous films with high specific surface areas. Benefitting from their unique structural features, binder-free Fe2 O3 and V2 O5 porous nanofiber electrodes offer high specific capacitances of 255 F g-1 and 256 F g-1 , respectively, at 2 mV s-1 in 1 m aqueous Na2 SO4 as electrolyte. An all-solid-state asymmetric supercapacitor (ASC) has been fabricated using Fe2 O3 and V2 O5 nanofibers as negative and positive electrodes, respectively. It could be operated at up to 1.8 V, taking advantage of the wide and opposite potential windows of the respective electrodes. The assembled all-solid-state ASC achieved a high energy density up to 32.2 W h kg-1 at an average power density of 128.7 W kg-1 , and exhibited excellent cycling stability and power capability. The effective and facile synthesis method and superior electrochemical performance described herein make electrospun Fe2 O3 and V2 O5 NFs promising electrode materials for high-performance ASCs.

Spherical α-MnO2 Supported on N-KB as Efficient Electrocatalyst for Oxygen Reduction in Al-Air Battery.

Traditional noble metal platinum (Pt) is regarded as a bifunctional oxygen catalyst due to its highly catalytic efficiency, but its commercial availability and application is often restricted by high cost. Herein, a cheap and effective catalyst mixed with α-MnO2 and nitrogen-doped Ketjenblack (N-KB) (denoted as MnO2-SM150-0.5) is examined as a potential electrocatalyst in oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). This α-MnO2 is prepared by redox reaction between K2S2O8 and MnSO4 in acid conditions with a facile hydrothermal process (named the SM method). As a result, MnO2-SM150-0.5 exhibits a good catalytic performance for ORR in alkaline solution, and this result is comparable to a Pt/C catalyst. Moreover, this catalyst also shows superior durability and methanol tolerance compared with a Pt/C catalyst. It also displays a discharge voltage (~1.28 V) at a discharge density of 50 mA cm-2 in homemade Al-air batteries that is higher than commercial 20% Pt/C (~1.19 V). The superior electrocatalytic performance of MnO2-SM150-0.5 could be attributed to its higher Mn3+/Mn4+ ratio and the synergistic effect between MnO2 and the nitrogen-doped KB. This study provides a novel strategy for the preparation of an MnO2-based composite electrocatalyst.

Co3O4-CeO2/C as a Highly Active Electrocatalyst for Oxygen Reduction Reaction in Al-Air Batteries.

Developing high-performance and low-cost electrocatalysts for oxygen reduction reaction (ORR) is still a great challenge for Al-air batteries. Herein, CeO2, a unique ORR promoter, was incorporated into ketjenblack (KB) supported Co3O4 catalyst. We developed a facile two-step hydrothermal approach to fabricate Co3O4-CeO2/KB as a high-performance ORR catalyst for Al-air batteries. The ORR activity of Co3O4/KB was significantly increased by mixing with CeO2 nanoparticles. In addition, the Co3O4-CeO2/KB showed a better electrocatalytic performance and stability than 20 wt % Pt/C in alkaline electrolytes, making it a good candidate for highly active ORR catalysts. Co3O4-CeO2/KB favored a four-electron pathway in ORR due to the synergistic interactions between CeO2 and Co3O4. In full cell tests, the Co3O4-CeO2/KB exhibited a higher discharge voltage plateau than CeO2/KB and Co3O4/KB when used in cathode in Al-air batteries.

Modification on the conventional procedure to measure AOC in drinking water.

Additional phosphorus will be introduced to water sample if the conventional procedure is used to measure assimilable organic carbon (AOC) in drinking water. It has been shown that there are the cases that phosphorus is the limiting nutrient for microbial growth in drinking water. The measured value of AOC would not be able to indicate appropriately the regrowth potential of bacteria in this case. The conventional procedure used to measure AOC was modified to avoid the introduction of additional phosphorus to water sample in this study. It was shown that it was feasible to measure AOC in water using the modified procedure. Furthermore, the measured value of AOC determined by the modified procedure could indicate appropriately the regrowth potential of bacteria in drinking water despite either organics or phosphorus was the limiting nutrient for bacterial regrowth.