An azine-linked 2D porphyrinic covalent organic framework for red light photocatalytic oxidative coupling of amines

The construction of two-dimensional covalent organic frameworks (2D COFs) with robust stability for photocatalysis has gained intensive attention recently. Herein, we report the design and synthesis of a highly crystalline azine-linked porphyrinic 2D COF (Por-HZ-COF). Our results clearly show that Por-HZ-COF adopts an eclipsed AA stacking structure with a high Brunauer-Emmett-Teller (BET) specific surface area of 1586 m²/g. In addition, Por-HZ-COF is chemically stable under various conditions, even in 12 M sodium hydroxide aqueous solution or 9 M hydrochloric acid. Moreover, Por-HZ-COF can be used for the photocatalytic aerobic oxidative coupling of benzylamines under red light irradiation with high activity and good reusability. This study demonstrates a novel robust 2D COF with azine linkage that has promising applications in photocatalysis.     

Enhancing the photothermal conversion of tetrathiafulvalene-based MOFs by redox doping and plasmon resonance

Near-infrared (NIR) photothermal materials hold great promise for use in several applications, particularly in photothermal therapy, diagnosis, and imaging. However, current NIR responsive materials often show narrow absorption bands and low absorption efficiency, and have long response times. Herein, we demonstrate that the NIR absorption of tetrathiafulvalene-based metal–organic frameworks (MOFs) can be tuned by redox doping and using plasmonic nanoparticles. In this work, a MOF containing redox-active tetrathiafulvalene (TTF) units and Dy-carboxylate chains was constructed, Dy-m-TTFTB. The NIR absorption of the as-synthesized Dy-m-TTFTB was further enhanced by Ag⁺ or I₂ oxidation, transforming the neutral TTF into a TTF˙⁺ radical state. Interestingly, treatment with Ag⁺ not only generated TTF˙⁺ radicals, but it also formed Ag nanoparticles (NPs) in situ within the MOF pores. With both TTF˙⁺ radicals and Ag NPs, Ag NPs@Dy-m-TTFTB was shown to exhibit a wide range of absorption wavelengths (200–1000 nm) and also a high NIR photothermal conversion. When the system was irradiated with an 808 nm laser (energy power of 0.7 W cm⁻²), Ag NPs@Dy-m-TTFTB showed a sharp temperature increase of 239.8 °C. This increase was higher than that of pristine Dy-m-TTFTB (90.1 °C) or I₂ treated I₃⁻@Dy-m-TTFTB (213.0 °C).

The photo-response of the redox-active metal–organic framework has been systematically tuned by incorporating plasmonic Ag nanoparticles and tetrathiafulvalene radicals, resulting in efficient near-infrared photothermal conversion materials.     

Use of graphene coated with ZnO nanocomposites for microextraction in packed syringe of carbamate pesticides from juice samples

In this work, nanocomposites of reduced graphene oxide coated with ZnO were synthesized using a hydrothermal reduction strategy. Nanocomposite was then used as a sorbent for microextraction in a packed syringe, and its application to the extraction of carbamate pesticides from juice samples prior to high‐performance liquid chromatography detection was demonstrated. Factors affecting the enrichment efficiency of the microextraction in a packed syringe procedure were optimized, which included desorption conditions, sample pH, salting‐out effect, washing solution, and sample cycles. Under optimal conditions, the prepared materials exhibited excellent enrichment efficiency for carbamate pesticides. Good linearity existed in the concentration range of 0.5–200 ng/mL, with correlation coefficients of 0.9991–0.9997. The limits of detection of these carbamate pesticides were in the range of 0.23–1.21 ng/mL, and the average recoveries of the analytes at two spiked levels for real‐sample analysis ranged from 90.5 to 104.2% with relative standard deviations of 3.6–5.9%.     

A discrete method based on distance measure in linguistic space and its application for CMADM problem

ABSTRACT

Owing to the complexity of decision environment, not all the attributes in multiple attribute decision making are quantitative. There are also some qualitative attributes, which are related to the integration of multiple attribute decision making (MADM) and linguistic multiple attribute decision making (LMADM). The specific method for composite multiple attribute decision making (CMADM) problems is crucial for decision maker (DM) to make scientific decision. In this paper, the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method is extended to a Composite Technique for Order Preference by Similarity to an Ideal Solution (CTOPSIS) method to solve the CMADM problems. As the basis of the CTOPSIS method, the distance measure model in linguistic space and in n-dimension linguistic space is generated based on the non-linear mapping. Based on the distance measure in linguistic space, a standard deviation method is taken to get the attribute weight. At the same time, the distance measure models are proposed based on the distance measure in n-dimension linguistic space, which are used to calculate the distance between the alternatives and the positive and negative idea points separately. Furthermore, a CTOPSIS method is generated to solve the CMADM problems. Finally, a numerical example is illustrated to explain the process. And the result shows that the CTOPSIS method is quite practical and more approximate to the real decision making situation.     

Gorenstein Star Modules and Gorenstein Tilting Modules

Czechoslovak Mathematical Journal - We introduce the notion of Gorenstein star modules and obtain some properties and a characterization of them. We mainly give the relationship between...     

Quasi-cotilting modules and hereditary quasi-cotilting modules

In this paper, we firstly give some basic properties on quasi-cotilting modules. With the help of these properties, we obtain a Quasi-cotilting Theorem (see Theorem 2.8). In particular, the Cotilting Theorem in [5 Colpi, R. R. (2000). Cotilting bimodules and their dualities. Lect. Notes Pure Appl. Math. 210:81–94. [Google Scholar]] is a corollary of our result. Finally, we introduce a new notion, hereditary quasi-cotilting modules, and mainly prove that the class consisting of all Δ-reflexive modules for a hereditary quasi-cotilting module is closed under submodules.     

Theoretical determination of the rate coefficient for the HO2 + HO2 → H2O2+O2 reaction: adiabatic treatment of anharmonic torsional effects

The HO(2) + HO(2) → H(2)O(2) + O(2) chemical reaction is studied using statistical rate theory in conjunction with high level ab initio electronic structure calculations. A new theoretical rate coefficient is generated that is appropriate for both high and low temperature regimes. The transition state region for the ground triplet potential energy surface is characterized using the CASPT2/CBS/aug-cc-pVTZ method with 14 active electrons and 10 active orbitals. The reaction is found to proceed through an intermediate complex bound by approximately 9.79 kcal/mol. There is no potential barrier in the entrance channel, although the free energy barrier was determined using a large Monte Carlo sampling of the HO(2) orientations. The inner (tight) transition state lies below the entrance threshold. It is found that this inner transition state exhibits two saddle points corresponding to torsional conformations of the complex. A unified treatment based on vibrational adiabatic theory is presented that permits the reaction to occur on an equal footing for any value of the torsional angle. The quantum tunneling is also reformulated based on this new approach. The rate coefficient obtained is in good agreement with low temperature experimental results but is significantly lower than the results of shock tube experiments for high temperatures.