Dual-band pixelless upconversion imaging devices

We have proposed a type of mid-infrared (MIR) and far-infrared (FIR) dual-band imaging device, which employs the photon frequency upconversion concept in a GaN/AlGaN MIR and FIR dual-band detector integrated with a GaN/AlGaN violet light emitting diode. On the basis of the photoresponse of single-period GaN/AlGaN dual-band detectors, we present the detailed optimization of multiperiod GaN emitter/AlGaN barrier detectors and their applications to dual-band pixelless upconversion imaging. Satisfying images have been received through the analysis of the modulation transfer function and the upconversion efficiency in the GaN/AlGaN dual-band pixelless upconverters, which exhibit good image resolution, high quantum efficiency, and negligible cross talk.     

Cu6S4 cluster based twelve-connected face-centered cubic and Cu19I4S12 cluster based fourteen-connected body-centered cubic topological coordination polymers

Hydrothermal reaction of Cu(MeCO2)2, (4-pyridylthio)acetic acid and NH4SCN resulted in a twelve-connected face-centered cubic topological metal-organic framework [Cu3(pdt)2(CN)] (pdt = pyridinethiolate) in which Cu6S4 clusters act as twelve-connected nodes and pyridine rings and cyanides act as connectors. As an extension, an unprecedented fourteen-connected body-centered cubic coordination polymer [Cu19I4(pdt)12(SH)3] has been synthesized by three methods, in which nanosized chiral Cu19I4S12 clusters act as fourteen-connected nodes and triple pyridine rings and hydrosulfides act as connectors. The in situ S-C(sp(3)), S-C(sp(2)), and S-C(sp) cleavage reactions have been observed in the work.     

An efficient route to 4-halophosphaisocoumarins via CuX2-mediated direct halocyclization of 2-(1-alkynyl)phenylphosphonic acid diesters

A series of 4-halophosphaisocoumarins were synthesized via CuX2 (X = Br, Cl) -mediated direct halocyclization of 2-(1-alkynyl)phenylphosphonic acid diesters in dichloroethane with the addition of n-Bu4NX or/and AgI in good to excellent yields. This reaction provides an efficient route to 4-halophosphaisocoumarins and represents the first example of bromo- and chlorocyclization of unsaturated phosphonic acid diesters.     

Rapid formation and slow collapse of a carbocation-anion pair to a neutral molecule

The 4,4',4' '-trimethoxytrityl cation (TMT(+)) was observed to react with acetate ion in acetic acid reversibly to give the corresponding ester (TMT-OAc). The rate of the reaction was found to be independent of [NaOAc] over a 25000-fold range. Similar results were observed in the presence of Bu(4)N(+) in acetic acid as well as in HOAc/AN (1/1). It was concluded that {TMT(+) (HOAc/AcO(-))} is an ion pair that forms essentially completely from free TMT(+) and HOAc/AcO(-) during the time of mixing under stopped-flow conditions. The process which was studied kinetically is the intramolecular collapse of the ion pair to TMT-OAc which takes place in two steps involving a kinetically significant intermediate. The remarkably close resemblance of this reaction to the Winstein scheme for solvolysis reactions is noted. In analogy to the Winstein scheme, it was proposed that the intermediate could be an intimate ion pair formed upon extrusion of solvent from the solvent separated ion pair. The product-forming step could then correspond to the intimate ion pair reacting further to form a covalent bond between the two moieties within the complex. The values of the thermodynamic and the activation parameters as well as the apparent rate constants for the reaction in the presence of either sodium or tetrabutylammonium ions suggest that these counterions play insignificant roles in the reactions. However, the equilibrium constant for the intramolecular step (K(4)) was observed to be two times greater in the presence of Bu(4)N(+) than in the presence of Na(+). The rate of the reaction in HOAc was observed to be about four times as great as that in HOAc/AN (1/1).     

Influence of Freezing Layer on the Crystallization Kinetics of PCL on Oriented PE Film

The effect of freezing layer on the crystallization kinetics of poly(ε-caprolactone)(PCL) thin and ultrathin films was investigated by monitor the growth process of it on oriented polyethylene(PE) and CaF₂ with and without freezing layer, respectively. It was found that the PCL films with similar thicknesses crystallize much faster on oriented PE than on CaF₂ substrate. For example, the crystallization rate constant of a 102 nm thick PCL film decreases tremendously by 3 ord...     

Talcum-doped composite separator with superior wettability and heatproof properties for high-rate lithium metal batteries

Separator is supposed to own outstanding thermal stability, superior wettability and electrolyte uptake,which is essential for developing high-rate and safe lithium metal batteries(LMBs). However, commercial polyolefin separators possess poor wettability and limited electrolyte uptake. For addressing this issue, we put forward a composite separator to implement above functions by doping layered-silicate(talcum) into polyvinylidene fluoride(PVDF). With significant improvement of electrolyte absor...     

Laser-ablated violet phosphorus/graphene heterojunction as ultrasensitive ppb-level room-temperature NO sensor

Two dimensional(2D) materials are promising gas sensing materials, but the most of them need to be heated to show promising sensing performance. Sensing structures with high sensing performance at room-temperature are urgent. Here, another 2D material, violet phosphorus(VP) nanoflake is investigated as gas sensing material. The VP nanoflakes have been effectively ablated to have layers of 1–5 layers by laser ablation in glycol. The VP nanoflakes are combined with graphene to form VP/G heterostru...     

Porous epoxy thermosets obtained by a reaction-induced process and their characterizations

A novel reaction-induced method with the aid of solvent for porous thermosetting epoxy was first carried out. Investigations of pore structure using scanning electron microscope （SEM） showed that porous epoxy networks with average pore size ranging from 3 to 20 μm were obtained. The pore structure generated by this method can be tailored by changing the solvent content.     

Determination of levodopa in pharmaceutical preparations by irreversible biamperometry

Based on the electrocatalytic oxidation of levodopa at gold electrode and the reduction of permanganate at platinum electrode, a novel flow injection irreversible biamperometric method is developed for the determination of levodopa under the potential difference of 0 V imposed between two electrodes. In H2SO4 solution, the linear relationships between currents and the concentrations of levodopa are obtained in the range from 0.04 mg/L to 20 mg/L with the detection limit of 0.012 mg/L. The proposed method is applied to the determination of levodopa in pharmaceutical preparations.     

Site-selective patterning of organic luminescent molecules via gas phase deposition

In this paper, we present a bottom-up approach to pattern organic luminescent molecules with a feature size down to sub-100 nm over wafer-sized areas. This method is based on the selective gas deposition of organic molecules on self-organized patterned structures, which consist of an organic monolayer with two different phases rather than different materials. The site selectivity is controllable by deposition rate and the pattern features. The reason for the site selectivity may be due to the nucleation and diffusion behaviors of the deposited organic molecules on different monolayer phases.