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      Physical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO and CH (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO permeability>7000 barrer.

      Working temperature, sensitivity, and selectivity are some of the characteristics of the applied gas sensors. How to design and fabricate an ideal gas sensor working at room temperature is still challenging and attracting lots of interest. Two-dimensional (2D) materials with ultra-thin structure have been demonstrated as a family of ideal candidates to achieve this goal. Among them, Ti C T MXene, a kind of layered sheet synthesized by selectively etching MAX phases materials, shows remarkable potential to be the sensitive materials solely or in a composite. However, their designing rules are still lacking critical thinking from the viewpoint of the intrinsic property of Ti C T MXene based materials. In this article, two critical features, i.e., the thickness of the sensitive materials, and the scope of the analytes, are elaborated towards Ti C T MXene based gas sensors after characterizing the performance of sensing reducing gases (NH and CO) and oxidizing gas (NO ). First, the thinner the Ti C T MXene sensitive layer, the better the sensitivity. Second, the Ti C T MXene based gas sensor is not suitable for strong and moderate oxidation gas due to its ease of oxidation. These two rules are demonstrated, and could be considered with priority both in the future researches and practical applications.

      Yingying Jian ,   Danyao Qu   et al.
      We demonstrate the fabrication of a new DNA sensor that is based on the optical interactions occurring between oligonucleotide-coated NaYF : Yb ; Er upconversion nanoparticles and the two-dimensional dichalcogenide materials, MoS and WS . Monodisperse upconversion nanoparticles were functionalized with single-stranded DNA endowing the nanoparticles with the ability to interact with the surface of the two-dimensional materials via van der Waals interactions leading to subsequent quenching of the upconversion fluorescence. By contrast, in the presence of a complementary oligonucleotide target and the formation of double-stranded DNA, the upconversion nanoparticles could not interact with MoS and WS , thus retaining their inherent fluorescence properties. Utilizing this sensor we were able to detect target oligonucleotides with high sensitivity and specificity whilst reaching a concentration detection limit as low as 5 fmol·L , within minutes.

      To realize the utilization of visible light and improve the photocatalytic efficiency of organic pollutant degradation in wastewater, a nitrogen-doped titanium-carbon composite (N-TiO /AC) prepared by sol-gel methods was applied in the photodegradation of phenol assisted by persulfate under visible light irradiation (named N-TiO /AC/PS/VIS). The results show that a synergistic effect exists between visible-light photocatalysis and persulfate activation. Compared with TiO /PS/VIS, the phenol degradation rate was found to be observably improved by 65% in the N-TiO /AC/PS/VIS system. This significant increase in degradation rate was mainly attributed to the following two factors: 1) The N and C doping can change the crystal structure of TiO , which extends the TiO absorption wavelength range to the visible light region. 2) As an electron acceptor, PS can not only prevent electrons and holes from recombining with each other but can also generate strong oxidizing radicals such as ?SO and ?OH to accelerate the reaction dynamics. The process of phenol degradation was found to be consistent with the Langmuir pseudo-first-order kinetic model with an apparent rate constant of 1.73 min . The N-TiO /AC/PS/VIS process was proven to be a facile method for pollutant degradation with high pH adaptability, excellent visible-light utilization and good application prospects.

      Yan Cui ,   Zequan Zeng   et al.

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