Crosslinkable high dielectric constant polymer dielectrics for low voltage organic field‐effect transistor memory devices

I n this study, we successfully synthesized water/methanol soluble random copolymers with a high dielectric constant, poly(n‐(hydroxymethyl) acrylamide‐co‐5‐(9‐(5‐(diethylamino)pentyl)?2‐(4‐vinylphenyl)?9H‐fluorene(P(NMA‐co‐F6NSt)), which contained chemical crosslinkable segment (NMA) and hole trapping building block (F6NSt). The feeding molar ratios of two monomers (NMA:F6NSt) were set as 100:0, 95:5, 80:20, and 67:33 for the copolymers of P1 , P2 , P3, and P4 , respectively. The crosslinked P(NMA‐co‐F6NSt) thin film could serve as both dielectric and charge storage layers in organic field‐effect transistor (OFET) memory device and exhibited high k (i.e., 4.91–6.47) characteristics, leading to a low voltage operation and a small power consumption. Devices based on the P1 ‐ P4 dielectrics showed excellent insulating properties and good charge storage performance under a low operating voltage in a range of ±5V because of tightly network structures and well‐dispersed trapping cites. In particular, P3 ‐based memory device exhibited a large memory window of 4.13 V with stable data retention stability over 10⁴ s, a large on/off ratio of 10⁴, and good endurance characteristics as high as 200 cycles. The above results suggested that a high‐performance OFET memory device could be facilely achieved using the novel crosslinkable high‐k copolymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3224–3236     

On an Entropy of Z_+~k-Actions

In this paper,a definition of entropy for Z+k(k≥2)-actions due to Friedland is studied.Unlike the traditional definition,it may take a nonzero value for actions whose generators have finite(even zero) entropy as single transformations.Some basic properties are investigated and its value for the Z+k-actions on circles generated by expanding endomorphisms is given.Moreover,an upper bound of this entropy for the Z+k-actions on tori generated by expanding endomorphisms is obtained via the preimage entropies,which are entropy-like invariants depending on the "inverse orbits" structure of the system.     

Blended-fuel based EDC combustion model and its application in heptane-ethanol fire simulation

The blended-fuel based eddy-dissipation-concept combustion model was newly developed in the FireFOAM framework, and applied to simulate 30 cm×30 cm heptane-ethanol pool fire. Comparison was made of fire height, centerline temperature against experimental measurements, which shows that they match very well with each other. However, further studies are needed to examine the validation of this model in fire simulations with various scales.     

ZnO‐Coated Carbon Nanotubes: Inter‐Diffusion of Carboxyl Groups and Enhanced Photocurrent Generation

ZnO is a defect‐governed oxide and emits light at both visible and UV regimes. This work employs atomic layer deposition to produce oxide particles on oxygenated carbon nanotubes, and the composites only show emission profiles at short wavelengths. The quenching of defect‐related emissions at long wavelengths is verified, owing to carboxyl diffusion into oxygen vacancies, and doping is supported by ZnCO₃ formation in oxide lattice. Fully coated tubes display an increased photocurrent and the quantum efficiency increases by 22 % relative to the bare nanotubes.     

Development of Ar‐BINMOL‐Derived Atropisomeric Ligands with Matched Axial and sp3 Central Chirality for Catalytic Asymmetric Transformations

Recently, academic chemists have renewed their interest in the development of 1,1′‐binaphthalene‐2,2′‐diol (BINOL)‐derived chiral ligands. Six years ago, a working hypothesis, that the chirality matching of hybrid chirality on a ligand could probably lead to high levels of stereoselective induction, prompted us to use the axial chirality of BINOL derivatives to generate new stereogenic centers within the same molecule with high stereoselectivity, obtaining as a result sterically favorable ligands for applications in asymmetric catalysis. This Personal Account describes our laboratory's efforts toward the development of a novel class of BINOL‐derived atropisomers bearing both axial and sp³ central chirality, the so‐called Ar‐BINMOLs, for asymmetric synthesis. Furthermore, on the basis of the successful application of Ar‐BINMOLs and their derivatives in asymmetric catalysis, the search for highly efficient and enantioselective processes also compelled us to give special attention to the BINOL‐derived multifunctional ligands with multiple stereogenic centers for use in catalytic asymmetric reactions.

     

Systematic chemical profiling of a multicomponent Chinese herbal formula Huo Luo Xiao Ling Dan by ultra high performance liquid chromatography coupled with electrospray ionization quadrupoletime‐of‐flight mass spectrometry

Huo Luo Xiao Ling Dan, a Chinese herbal formula consisting of 11 different herbs, has been used in folk medicine for the treatment of arthritis and other chronic inflammatory diseases. However, the chemical compositions of Huo Luo Xiao Ling Dan are not completely characterized. In the present study, an ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight mass spectrometry method in positive and negative ion modes was employed to identify biochemical constitutes in Huo Luo Xiao Ling Dan. As a result, a total of 76 compounds including alkaloids, monoterpene glycosides, iridoids, phenolic acids, and tanshinones, coumarins, lactones, flavones, and their glycosides, triterpenes, and triterpene saponins were characterized by comparing the retention time and mass spectrometry data with reference standards within 5 ppm error or by reference to the reference literature. These results would provide the basis for a further in vivo study of Huo Luo Xiao Ling Dan and information for potential new drug candidates for treating arthritis and other chronic inflammatory diseases.     

Ionic liquid and aqueous two‐phase extraction based on salting‐out coupled with high‐performance liquid chromatography for the determination of seven rare ginsenosides in Xue‐Sai‐Tong injection

A method of ionic liquid salt aqueous two‐phase extraction coupled with high‐performance liquid chromatography has been developed for the analysis of seven rare ginsenosides including Rg₆, F₄, 20(S)‐Rg₃, 20(R)‐Rg₃, Rk₃, Rk₁, and Rg₅ in Xue‐Sai‐Tong injection. The injection was mixed with ionic liquid 1‐butyl‐3‐methylimidazolium bromide aqueous solution, and a mixture was obtained. With the addition of sodium dodecyl sulfate and dipotassium phosphate into the mixture, the aqueous two‐phase mixture was formed after ultrasonic treatment and centrifuged. Rare ginsenosides were extracted into the upper phase. To obtain a high extraction factors, various influences were considered systematically, such as the volume of ionic liquid, the category and amount of salts, the amount of sodium dodecyl sulfate, the pH value of system, and the time of ultrasonic treatment. Under the optimal condition, rare ginsenosides in Xue‐Sai‐Tong injection were enriched and detected, the recoveries of seven rare ginsenosides ranged from 90.05 to 112.55%, while relative standard deviations were lower than 2.50%. The developed method was reliable, rapid and sensitive for the determination of seven rare ginsenosides in the injections.