Bowen Cheng

Ionic liquid [EMIM]OAc under ultrasonic irradiation towards the first synthesis of trisubstituted imidazoles.

The ionic liquid 1-ethyl-3-methylimidazole acetate ([EMIM]OAc) was found to be a mild and effective catalyst for the efficient, one-pot, three-component synthesis of 2-aryl-4,5-diphenyl imidazoles at room temperature under ultrasonic irradiation. This procedure has many obvious advantages compared to those reported in the previous literatures, including avoiding the use of harmful catalysts, reacting at room temperature, high yields, simplicity of the methodology.

A review of recent developments in rechargeable lithium–sulfur batteries

The research and development of advanced energy-storage systems must meet a large number of requirements, including high energy density, natural abundance of the raw material, low cost and environmental friendliness, and particularly reasonable safety. As the demands of high-performance batteries are continuously increasing, with large-scale energy storage systems and electric mobility equipment, lithium-sulfur batteries have become an attractive candidate for the new generation of high-performance batteries due to their high theoretical capacity (1675 mA h g-1) and energy density (2600 Wh kg-1). However, rapid capacity attenuation with poor cycle and rate performances make the batteries far from ideal with respect to real commercial applications. Outstanding breakthroughs and achievements have been made to alleviate these problems in the past ten years. This paper presents an overview of recent advances in lithium-sulfur battery research. We cover the research and development to date on various components of lithium-sulfur batteries, including cathodes, binders, separators, electrolytes, anodes, collectors, and some novel cell configurations. The current trends in materials selection for batteries are reviewed and various choices of cathode, binder, electrolyte, separator, anode, and collector materials are discussed. The current challenges associated with the use of batteries and their materials selection are listed and future perspectives for this class of battery are also discussed.

Solution blowing of submicron-scale cellulose fibers.

Solution blowing is an innovative process for spinning micro-/nano-fibers from polymer solutions using high-velocity gas flow as fiber forming driving force. Submicron-scale cellulose fibers were successfully solution blown by two improvement measures. First, cellulose solution was directly blown to fibers of 260-1900 nm in diameter by raising the air temperature along the spinning line which was proved to accelerate the evaporation of solvent and fiber forming. Second, coaxial solution blowing technique was established with cellulose solution and polyethylene oxide (PEO) solution used as core and shell liquids, respectively. The core-shell structures of the fibers were examined by SEM and TEM. Cellulose fibers with diameter between 160 nm and 960 nm were further obtained after removing PEO shell. X-ray diffraction studies showed that the two kinds of submicron-scale cellulose fibers are mostly amorphous.

Ultrasound-promoted synthesis of oximes catalyzed by a basic ionic liquid [bmIm]OH.

The basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, [bmIm]OH, efficiently catalyzes the condensation reaction of aldehydes and ketones with hydroxylamine hydrochloride under ultrasound irradiation. Compared with conventional methods, the main advantages of the present procedure are milder conditions, shorter reaction time and higher yields.

Solution blowing of chitosan/PVA hydrogel nanofiber mats

Both nanofiber mats and hydrogel have their own advantages in wound healing. In this study, a novel hydrogel nanofiber mats were fabricated via solution blowing of chitosan and PVA solution, with various content of ethylene glycol diglycidyl ether (EGDE) as cross-linker. SEM observation showed that the fibers were several hundred nanometers in diameter with smooth surface and distributed randomly forming three-dimensional mats. The structure of the chitosan/PVA nanofibers was examined by FTIR and XPS, and the results showed that the cross-linking reaction occurred between EGDE and the hydroxyl groups. The mats could quickly hydrate in an aqueous environment to form hydrogel. Their value of equilibrate water absorption varied from 680 to 459% various content of EGDE. The nanofiber mats showed good bactericidal activity against Escherichia coli. The chitosan/PVA hydrogel nanofiber mats showed the combination advantages of nanofibrous mats and hydrogel dressing, and were suggested as potential application in wound healing.

An efficient ultrasound-promoted method for the one-pot synthesis of 7,10,11,12-tetrahydrobenzo[c]acridin-8(9H)-one derivatives

A new, efficient and general method for preparation of 7,10,11,12-tetrahydrobenzo[c]acridin-8(9H)-one derivatives using ultrasound irradiation is reported. Under ultrasound, the reaction time is short, the yields are high and the reaction conditions are mild.

Organically modified MCM-type material preparation and its usage in controlled amoxicillin delivery

MCM-41 was grafted with 3-aminopropyl trimethoxysilane (APTMS), 3-chloropropyltriethoxysilane (CPTMS) to give organic group modified samples, and l-tryptophane was covalently immobilized onto organic samples to improve the physicochemical properties of mesoporous silica to controlled amoxicillin delivery. Samples were characterized by X-ray diffraction (XRD), N(2) adsorption-desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy, and characterized results demonstrated that organic groups were successfully grafted onto the samples. The results of amoxicillin release exhibited that 12.9wt% and 33.0wt% impregnated amoxicillin could be released from the post-grafting MCM-41 with APTMS and pure MCM-41 after 24h, however, 41.0wt% impregnated amoxicillin could be released from the post-grafting MCM-41 with CPTMS after 24h. When the samples modified with APTMS and CPTMS were further grafted by l-tryptophane, the slower drug release rate was achieved over samples with l-tryptophane immobilization. The release profiles of all samples indicated that the amoxicillin release was mainly regulated by the diffusion mechanism.

Ionic liquid under ultrasonic irradiation towards a facile synthesis of pyrazolone derivatives.

Ionic liquid [HMIM]HSO(4) was found to be an efficient catalyst for the synthesis of 4-[(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-phenyl-methyl]-5-methyl-2-phen-yl-1,2-dihydro-pyrazol-3-ones through the condensation reaction of arylaldehydes and 3-methyl-1-phenyl-5-pyrazolone under ultrasonic irradiation at room temperature. The present methodology offers several advantages such as excellent yields, simple procedure and mild conditions.

Solution blowing of ZnO nanoflake-encapsulated carbon nanofibers as electrodes for supercapacitors

A facile spinning-based strategy is developed to fabricate zinc oxide nanoflake-encapsulated carbon nanofibers (ZnO/CNFs) as electrodes for supercapacitors. The zinc oxide/carbon nanofiber mats were solution blown with zinc acetate (Zn(Ac)2) and polyacrylonitrile (PAN) as the metal and carbon precursor to get Zn(Ac)2 core-enriched precursor nanofibers. After annealing under nitrogen, the precursor nanofibers were converted to ZnO/CNFs with ZnO nanoflakes encapsulated in the core of carbon nanofibers. In the constructed architecture, carbon nanofibers can avoid the direct exposure of ZnO to the electrolyte and preserve the structural and interfacial stabilization of ZnO nanoflakes. Meanwhile, the flexible entangled carbon nanofibers can accommodate temperate porosities thus providing the pore channel for electrolyte ions and maintain the structural and electrical integrity of the ZnO/CNF electrode during the charge–discharge processes. By loading different contents of ZnO, the microstructures of CNFs were changed, and the textural parameters significantly affected their electrochemical properties as electrodes. As a result, the ZnO/CNF electrodes exhibit high specific capacitance (216.3, 212.7, 208.8 and 172.5 F g−1 at 1, 5, 10, and 50 A g−1, respectively) and extremely excellent cycling performance at high current density (only 5.41% capacitance loss after 2000 cycles at a high rate of 10 A g−1), with promising energy densities of 29.76 kW h kg−1, over a power density range of 2.5–30 kW kg−1. The ZnO/CNFs simultaneously exhibit excellent capacity retention. These encouraging results indicate great potential applications of ZnO/CNFs in developing energy storage devices with high energy and power densities.

Role of a gradient interface layer in interfacial enhancement of carbon fiber/epoxy hierarchical composites

To improve the interfacial properties of carbon fibers/epoxy composites, we introduced a gradient interphase reinforced by graphene sheets between carbon fibers and matrix with a liquid phase deposition strategy. Interlaminar shear strength and flexural strength of the composites are both improved. The interfacial reinforcing mechanisms are explored by analyzing the structure of interfacial phase with linear scanning system of scanning electron microscope and atomic force microscope. Results indicate that carbon element shows a graded dispersion in the interface region and a gradient interface layer with the modulus decreasing from fibers and matrix is found to be built. To verify the effect of gradient interphase on the interfacial properties of composites, the mixture of carbon fiber/graphene/epoxy is sonicated before curing to disperse graphene sheets in matrix homogeneously. As a result, gradient interphase structures are disappeared and interfacial performance of composites is found to be weakened. The role of gradient interface layers in enhancing interfacial performances is further proved from a different angle.