A thermal stable cathode buffer based on an inexpensive tetranuclear zinc(II) complex for organic photovoltaic devices

An inexpensive material,i.e.,tetranuclear zinc(Ⅱ) complex,(Zn4O(AID)6) [AID = 7-azaindolate],was utilized as a cathode buffer in organic photovoltaic(OPV) devices,leading to the improvement of device performance.Compared to OPV devices based on a conventional cathode buffer of TPBi(1,3,5-tris(2-N-phenylbenzimidazolyl)benzene),although the freshly prepared devices showed similar performance,when heated to a series of high temperatures under air,the short circuit current and the open circuit voltage of the Zn4O(AID)6 devices dropped more slowly,indicating the superiority of using Zn4O(AID)6 as a cathode buffer over TPBi in OPV devices.     

Correlated scale-free network with community: modeling and transportation dynamics

Many transport processes on network depend crucially on the underlying network topology. In this paper, we propose a model to generate correlated scale free transportation networks with community structure by considering the mechanisms of dynamical network evolution and rewiring links. With the introduction of congestion effects, we investigate the performance and carrying capacity of this network. The results show that congestion in the uncorrelated network is more serious than the assortative or disassortative ones. Therefore, the correlated network with communities can bear much more traffic flow. In addition, the networks with lager modularity can enhance the transportation efficiently.     

Layer-by-layer inkjet printing of fabricating reduced graphene-polyoxometalate composite film for chemical sensors

Graphene oxide (GO) nanosheets and polyoxometalate such as H(3)PW(12)O(40) (PTA) are prepared into a multilayer film via a layer-by-layer inkjet printing method. The GO/PTA composite thin film shows linear, uniform and regular layer-by-layer growth. Under UV-irradiation, a photoreduction reaction takes place in the film which converts GO to reduced GO (rGO) due to the photoreduction activity of polyoxometalate clusters. According to the cyclic voltammograms measurement, the rGO/PTA composite film displays good electrocatalytic activity for the oxidation of dopamine (DA). The oxidation peak current (I(pa)) increases gradually with increasing the dopamine concentration, which may be used in electrochemical biosensors.     

Optimal constant weight covering codes and nonuniform group divisible 3-designs with block size four

Let K _q (n, w, t, d) be the minimum size of a code over Z _q of length n, constant weight w, such that every word with weight t is within Hamming distance d of at least one codeword. In this article, we determine K _q (n, 4, 3, 1) for all n ≥ 4, q = 3, 4 or q = 2 ^m  + 1 with m ≥ 2, leaving the only case (q, n) = (3, 5) in doubt. Our construction method is mainly based on the auxiliary designs, H-frames, which play a crucial role in the recursive constructions of group divisible 3-designs similar to that of candelabra systems in the constructions of 3-wise balanced designs. As an application of this approach, several new infinite classes of nonuniform group divisible 3-designs with block size four are also constructed.     

Theoretical study on the degradation mechanism of methamidophos and chloramine phosphorus with OH radicals

Theoretical investigation on the gas‐phase degradation reaction mechanism of methamidophos (MAP) and chloramine phosphorus (CHP) with OH radicals is performed. The equilibrium geometries and the harmonic vibration frequencies of the stationary points are obtained at M06‐2x/6‐31+G(d,p) level, and the higher‐level energetic information is further refined at M06‐2x/6–311++G(3df,2p) level. The rate constants for the 14 reaction channels are calculated by the improved canonical variational transition state theory with small‐curvature tunneling correction over the temperature range 200–2000 K. The three‐parameter expressions of k₁(T) = 1.53 × 10^?19T^2.74exp(?1005.12/T), k₂(T) = 1.36 × 10^?20T^3.02exp(?1259.56/T) are given. The total rate constants of all reaction channels of MAP with OH radicals are in good agreement with the available experimental data. Our results indicate that the H‐abstraction reactions on methyl are the major channels for the reaction of MAP and CHP with OH radicals. © 2015 Wiley Periodicals, Inc.     

Sol–gel based synthesis of ultrafine tetragonal BaTiO3

Ultrafine tetragonal BaTiO₃ nanocrystals have been prepared by a sol–gel based method. By adjusting the volume ratio of H₂O/DEG (diethylene glycol) in the solutions, hydrolysis rate of tetra-n-butyl titanate was strongly inhibited and the particle size could be controlled as small as 4–8 nm. The powder X-ray diffraction and transmission electron microscopy characterizations exhibit that the nanocrystals are spherical and well crystallized. The Raman spectrum shows the products are composed of the orthorhombic phase and tetragonal phase. The Fourier transform infrared spectrum revealed that a surface modification layer was formed around the BaTiO₃ nanocrystals, which can prevent them from aggregation and help to form a stable, high solid content sol.     

Landfill leachate treatment using the sequencing batch biofilm reactor method integrated with the electro-Fenton process

A study was conducted on the treatment of landfill leachate by combining the sequencing batch biofilm reactor (SBBR) method with the electro-Fenton method. The reduction of chemical oxygen demand (COD), biological oxygen demand (BOD₅), and ammonia nitrogen (NH ₄ ⁺ -N) from the leachate by the SBBR method was investigated. For the electro-Fenton experiment, the changes in COD and total organic carbon (TOC) with the increase in H₂O₂ dosage and electrolysis time under optimal conditions were also analysed. The results showed that the average efficiencies of reduction of COD, BOD₅, and NH ₄ ⁺ -N achieved using the SBBR method were 21.6 %, 54.7 %, and 56.1 %, respectively. The bio-effluent was degraded by the subsequent electro-Fenton process, which was rapid over the first 30 min then subsequently slowed. After 60 min of the electro-Fenton treatment, the efficiencies of reduction of TOC, COD, and BOD₅ were 40.5 %, 71.6 %, and 61.0 %, respectively. There is a good correlation between the absorbance of leachate at 254 nm (UV₂₅₄) and COD or TOC during the electro-Fenton treatment.     

Environmental gamma background measurements in China Jinping Underground Laboratory

To determine the environmental gamma background levels which affects rare events experiments, we measured in situ gamma spectrum at four locations in the China Jinping Underground Laboratory. The integral background count rates (40–2,700 keV) varied from 3.76 to 74.1 cps. The average count rate of the measurements inside the CJPL was 73.4 cps. The spectrometer was calibrated with a ¹⁵²Eu point source and Monte Carlo simulation to obtain the activity conversion factors for the rock and the air, respectively. The rocks that surrounded the CJPL was characterized by very low activity concentrations of ²³⁸U (3.69–4.21 Bq kg^?1), ²³²Th (0.52–0.64 Bq kg^?1) and ⁴⁰K (4.28 Bq kg^?1).