Investigation on rapid degradation of sodium dodecyl benzene sulfonate (SDBS) under microwave irradiation in the presence of modified activated carbon powder with ferreous sulfate

The modification of activated carbon powder (ACP) with ferreous sulfate and the degradation of sodium dodecyl benzene sulfonate (SDBS) under microwave irradiation combined with the modified ACP were studied in this work. The research results showed that the catalytic activity of the modified ACP depended on the concentration and acidity of ferreous sulfate solution as well as immersing time. Also, the influences of irradiation time, initial concentration and acidity of SDBS solution and addition amount of modified ACP on the degradation were assessed. UV-vis spectra, FT-IR spectra, ionic chromatography, HPLC and TOC technologies were brought to bear in assessing the modification and the degradation processes. For modified ACP, under given conditions such as 100 mg/L SDBS solution, 1.20 g/L catalyst dose and pH = 6.0, a high degradation ratio (75.5%) was obtained for 25 mL solution within 90 s microwave irradiation, while it was only 59.59% for unmodified ACP. Furthermore, the degradation ratios could reach 100% by the appropriate increase of addition dose (e.g. 2.80 g/L) of modified ACP or the extension of irradiation time (e.g. 230 s). Whereas, for unmodified ACP, the corresponding degradation ratios were only 88.71% or 83.54%, respectively. Hence, it can be concluded that the method adopting microwave irradiation combined with the modified ACP reveals many advantages of rapid degradation rate, low cost, no residual intermediates and no secondary pollution in actual application.     

A semi-parametric approach for mixture models: Application to local false discovery rate estimation

A procedure to estimate a two-component mixture model where one component is known is proposed. The unknown part is estimated with a weighted kernel function. The weights are defined in an adaptive way. The convergence to a unique solution of our estimation procedure is proven. The procedure is compared with two classical approaches using simulation. In addition, the results obtained are applied to multiple testing procedure in order to estimate the posterior population probabilities and the local false discovery rate.     

Dynamic properties of aligned short carbon fibre-reinforced plastics in flexure and torsion

Theoretical and experimental studies of the dynamic material properties of short aligned carbon fibre-reinforced plastics are described. It is shown that, by correct choice of fibre aspect ratio and volume fraction, the damping of composites can be improved whilst retaining high modulus of elasticity. Both flexural and shear properties have been studied and experimental techniques for dynamic measurements are described. It is shown how material loss factors may be deduced from specimen loss factors and results are presented for a range of fibre lengths from 0.25 to 3.0 mm. Moulding techniques for manufacturing short aligned fibre-reinforced plastic rods and beams to a required fibre distribution and alignment have been developed.     

Co-rotational beam elements with warping effects in instability problems

The present paper investigates the formulation of 3D co-rotational beam elements for the buckling and post-buckling analysis of frame structures. Following Pacoste and Eriksson [Comput. Methods Appl. Mech. Engrg. 144 (1997) 163], the term co-rotational relates here to the provision of a local reference frame that continuously rotates and translates with the element. Within this context, several issues are emphasised. The first one refers to the parameterisation of finite 3D rotations. The alternative put forth in the paper is based on the spatial form of the incremental rotational vector. The second issue concerns warping effects which are introduced by adding a seventh degree of freedom at each node. Different types of local formulations are considered and it is shown that at least some degree of non-linearity must be introduced in the local strain definition in order to obtain correct results for certain classes of problems. Within the present approach the centroid and shear center of the cross-section are not necessarily coincident. Finally, in the context of instability problems, a method for the direct computation of critical points is also briefly discussed. This is based on a minimal augmentation procedure as developed by Eriksson [Comput. Methods Appl. Mech. Engrg. 156 (1998) 45; Comput. Methods Appl. Mech. Engrg. 179 (1999) 265; Int. J. Struct. Stability Dynamic 1 (1) (2001)]. Ten examples, including large displacement and stability problems, are used in order to assess the performances of the elements.     

Chemically prepared Polypyrrole/ZnWO4 nanocomposite electrodes for electrocatalytic water splitting

ZnWO₄, PPy, and PPy/ZnWO₄ nanoparticles were prepared using chemical synthesis. The structural, compositional and morphological properties of the prepared samples have been investigated using XRD, FTIR, SEM, and HRTEM respectively. The powder XRD reveals the monoclinic wolframite structure for both ZnWO₄ and PPy/ZnWO₄ nanocomposite. SEM confirms the wrapping of ZnWO₄ with PPy. The electrodes of ZnWO₄, PPy, and PPy/ZnWO₄ have been tested as bifunctional electrocatalyst towards HER and OER using constant current chronopotentiometry (CP) and Linear Sweep Voltammetry (LSV). The electrochemical surface area and the electrocatalytic activity PPy/ZnWO₄ nanocomposite towards HER and OER are greater than that of pure ZnWO₄ and PPy. The Tafel slope of PPy/ZnWO₄ nanocomposite is 76 and 84 mV dec⁻¹ in 0.5 M H₂SO₄ and 1 M KOH at room temperature for HER and OER respectively. The results suggest that PPy/ZnWO₄ nanocomposite is a good candidate for the bifunctional electrocatalyst for water splitting.     

Sensitization of europium(III) luminescence in bis(bipyridine) DTPA and DTTA-based ligands: effect of the deletion of amide groups

Two new ligands containing two 2,2^′-bipyridine groups and derived from diethylenetriaminepentaacetic acid (DTPA) (1) or diethylenetriaminetriacetic acid (DTTA) (2) were synthesized and the luminescent properties of their europium(III) complexes were investigated in aqueous solutions. In the two systems, the 2,2^′-bipyridine chromophores act as antenna for the sensitization of the lanthanide ion and are not coordinated to the metal. It is shown that the change in ligand structure from 1 to 2 creates a higher antenna-to-metal energy transfer, and consequently a better luminescence quantum yield.     

Evidence of triplet–triplet interaction in crystalline sexithiophene

Optically detected magnetic resonance (ODMR) experiments are performed at room temperature on crystalline sexithiophene (6T) photoluminescence (PL). The observed spectra are interpreted in terms of microwave induced transitions between spin sublevels of triplet–triplet pairs states. These triplets are produced by intersystem crossing and their mutual annihilation which leads to delayed fluorescence (DF) is modulated by the high power microwave and enhance the PL process.     

响应面优化酶法辅助提取山楂果胶及其体外抗氧化和抗糖化活性

本研究以山楂粉为原料,在木聚糖酶添加量、酶解温度、溶剂pH以及酶解时间4个单因素实验的基础上,采用响应面实验优化木聚糖酶提取山楂果胶的工艺,并对提取果胶的体外抗氧化和抗糖化能力进行了研究。结果表明,木聚糖酶提取山楂果胶的最优工艺条件为:木聚糖酶添加量70 U/g、pH7.0以及50.5℃,酶解时间为3.0 h,实得山楂果胶得率为16.8%±0.2%。在体外抗氧化和抗糖化实验中,随着果胶多糖浓度的增加,DPPH·清除率从19.4%增至63.7%,·OH清除率从10.1%增加到69.3%,O₂^-·清除率从12.8%增加到59.2%;在BSA-果糖模拟反应体系下,果胶的糖化抑制率从20.9%增加到55.4%,BSA-MGO(B)模拟反应体系下,果胶的糖化抑制率从10.7%增加到了55.9%,因此酶法提取的果胶多糖具有明显的体外抗氧化和抗糖化活性,并且其活性与浓度成正相关,是一种天然的食源性体外抗氧化和抗糖化试剂。     

Design of efficient noble metal single-atom and cluster catalysts toward low-temperature preferential oxidation of CO in H2

The preferential oxidation of CO in H₂ is attractive for the removal of trace amounts of CO to meet the requirement of proton-exchange membrane fuel cells (PEMFCs) application. The key is to design highly effective catalysts that work well in a wide range of low temperatures. Here, the recent progress in Au and Pt group metal catalysts for the PROX reaction is summarized, covering those with single-atom and cluster dispersed metal species with remarkable performance. Firstly, the progress of some representative catalysts is overviewed, with an emphasis on the strategies for improving low-temperature activity, selectivity, and stability. Then, special attention is focused on the key parameters affecting performance in the PROX reaction. Moreover, the reaction mechanisms in terms of adsorption and activation of reactants are discussed. Finally, the challenges and opportunities are offered for guiding the design of advanced noble metal catalysts toward the PROX process.