Engineered cellulose nanofibers membranes with oppositely charge characteristics for high-performance salinity gradient power generation by reverse electrodialysis.

Reverse electrodialysis (RED) using nanofluidic ion-selective membrane may convert the salinity difference between seawater and river water into electricity. However, heterogeneous modification reactions of cellulose commonly leads to the inhomogeneous distribution of surface charges, thereby hampering the improvement of cellulose-based nanofluidic membranes for energy conversion. Herein, RED devices based on cellulose nanofibers (CNF) membranes with opposite charge characteristics were developed for the generation of salinity gradient power. Anion-CNF membrane (A-CNF) with varying negative charge densities was synthesized using 2,2,6,6-Tetramethylpiperidine 1-oxy radical (TEMPO) oxidation modification, whereas cation-CNF membrane (C-CNF) was prepared through etherification. By mixing artificial seawater and river water, the output power density of CNF RED device is up to 2.87 W m-2. The output voltage of 30 RED units connected in series may reach up to 3.11 V, which can be used to directly power tiny electronic devices viz. LED lamp, calculator, etc. The results of this work provide a feasible possibility for widespread application of ion exchange membranes for salinity gradient energy harvesting.

Design of metallic phase WS2/cellulose nanofibers composite membranes for light-boosted osmotic energy conversion.

Osmotic energy reserves in estuaries, coupled with the ubiquitous solar energy, could be harnessed through emerging nanofluidic membranes to reduce the energy crisis. Herein, we mixed WS2 with high concentration of metal phase and cellulose nanofiber (CNF) to fabricate composite membranes by vacuum filtration. Incorporated CNF as space charge donors increases the ion flux through the enlarged interlayer spacing in the WS2/CNF composite membrane. By simulating seawater and river water, the power density of the composite membrane reached to 1.99 W m-2. Furthermore, due to the photoelectric characteristics of WS2, the composite membrane exhibits photoresponsivity, which generated a photocurrent of 177 nA through illumination. Taking the advantage of the optoelectronic properties of the composite membrane, the power density under illumination is twice than that of the dark state. Based on the results, this material design strategy can enhance the ion transport in nanofluidic membranes for efficient generation of clean energy.

Increased ion transport and high-efficient osmotic energy conversion through aqueous stable graphitic carbon nitride/cellulose nanofiber composite membrane.

Increased attention has evoked on the utilization of renewable energy, particularly osmotic power as a potential solution to the energy crisis and environmental pollution. Herein, we fabricate graphitic carbon nitride (g-C3N4)/cellulose nanofiber (CNF) composite membranes with tailored lamellar nanochannels for capturing osmotic energy from salinity gradients. Composite membranes exhibiting charge-governed ion conductivity were prepared via co-homogenization of g-C3N4 with CNF and vacuum filtration. Ion conductivity was efficiently modulated by fine-tuning the charge density through controlling the weight content of CNF in the composite membranes. Higher ion conductivity of 0.014 S cm-1 at low concentrations (<10-2 M KCl) was achieved due to the increased charge density of the lamellar nanochannels and the excellent aqueous stability of the membranes. We demonstrate the potential of the composite membranes in nanofluidic osmotic energy conversion, displaying thermo-enhanced power output performance. This work could inspire new designs of cellulose-based nanofluidic devices for improved osmotic energy conversion.

Laparoscopic radical hysterectomy with vaginectomy and reconstruction of vagina in patients with stage I of primary vaginal carcinoma.

OBJECTIVES: The purpose of this study was to retrospectively evaluate the technique, feasibility and oncological safety of laparoscopic radical hysterectomy with vaginectomy and reconstruction of vagina in patients with stage I primary vaginal carcinomas. METHODS: Between February 2003 and July 2004, four patients, that had needs of sexual life, aging from 41 to 61 years with stage I primary vaginal carcinoma located at the upper third or 2/3 of the vagina, were submitted to laparoscopic radical hysterectomy with vaginectomy and reconstruction of the vagina using the sigmoid colon. RESULTS: The average operative time was 305 min (range 260-350 min). The average estimated blood loss was 325 ml (range 250-400 ml), and the medial number of the lymph nodes removed was 16 (range 13-20). All surgical margins and nodes removed were negative histopathologically. There were no intra-operative and postoperative complications. The mean stay day after surgery was 7 days (range 6-8 days). The mean length of a neo-vagina was 13 cm (range 12-15 cm) and the introitus admitted two fingers in breadth. The mean follow-up was 46 months (range 40-54 months). All patients are clinically free of disease and have satisfactory sexual life. None require dilation of the introitus. During the first 6 months, all the patients had little complaints of excessive leucorrhoea. CONCLUSIONS: To our knowledge, this is the first reported laparoscopical radical surgery combined with reconstruction of the vagina in patients with early-stage primary vaginal cancer. Our results have demonstrated the oncological safety and feasibility of the laparoscopical procedure. Intermediate-term follow-up validates the adequacy of this procedure.