Liquid phase deposition of hemoglobin/SDS/TiO2 hybrid film preserving photoelectrochemical activity

This work demonstrates that liquid phase deposition (LPD) technique provides a novel approach to the immobilization of hemoglobin (Hb) in TiO(2) film for studying the direct electron transfer of Hb. Using the LPD process, a hybrid film composed of Hb, TiO(2) and sodium dodecylsulfonate (SDS) is successfully prepared on the electrode surface. The surface morphology of as-deposited Hb/SDS/TiO(2) film shows a flower-like structure. The cyclic voltammetric measurement indicates that the LPD hybrid film facilitates the electron transfer of Hb, which yields a pair of redox peaks prior to the characteristic voltammetric peaks of TiO(2). Due to the electrocatalytic activity of Hb towards H(2)O(2), the Hb/SDS/TiO(2) hybrid LPD film can be utilized as an H(2)O(2) sensor, showing a sensitive response linearly proportional to the concentration of H(2)O(2) in the range of 5.0×10(-7)-4.0×10(-5) mol/L. At the same time, the Hb/SDS/TiO(2) hybrid film preserves the photoelectrochemical activity of TiO(2). The photovoltaic effect on the electrochemical behavior of Hb/SDS/TiO(2) film is observed after long-time UV irradiation on the film, which could improve the calibration sensitivity for H(2)O(2).     

15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: evidence for a hydantoin derivative

A nitrogen-rich segment in a fulvic acid (FA) from Pony Lake, a coastal pond in Antarctica, was investigated by (15)N and (13)C{(14)N} solid-state NMR techniques. As reported previously, the (13)C{(14)N} spectrum of C bonded to N exhibits a peak at 157 ppm that is assigned to an sp(2)-hybridized carbon bonded to at least two nitrogen atoms. This segment contains 48% of all N in the sample. (15)N NMR shows distinct signals, 20 ppm upfield and downfield from the typical peptide resonance; dipolar dephasing confirmed that they are due to protonated N. The well-resolved downfield peak, which accounts for 1/4 of the spectral area, cannot be assigned to aromatic heterocycles, such as purines, because the fraction of aromatic C bonded to N in this sample is very small. Analysis of (15)N chemical-shift trends and (15)N NMR of model compounds, such as arginine and its derivatives, excludes assignment to a guanidinium ion or to substituted guanidino groups. Similarly, ureido groups, -NH-CO-NH-, that are not bonded to a second C = O do not match the observed (15)N peaks in the FA, since both N resonate upfield from the peptide resonance. On the other hand, all chemical shifts are matched within the observed range by the -C(alkyl)-NH-CO-NH-CO-C structure found in two nonaromatic heterocycles, hydantoin and dihydrouracil. The five-membered hydantoin ring, which is found in the purine metabolite allantoin, provides a better match than the six-membered dihydrouracil ring. Regular uracil or thymine fails to produce adequate agreement with observed chemical shifts.     

Enhanced activity and SO2 resistance of Co-modified CeO2-TiO2 catalyst prepared by facile co-precipitation for elemental mercury removal in flue gas

The Co-modified CeO₂-TiO₂ catalyst prepared by facile co-precipitation was used for efficient elemental mercury oxidation in flue gas. Results indicated that Co doping greatly enhanced the activity and SO₂ resistance of the CeO₂-TiO₂ catalyst. In the presence of 5% O₂, 500 ppm NO, 800 ppm SO₂ and 3% H₂O at 200 °C, the Hg⁰ removal efficiency of CeCo₃/Ti could maintain at about 87% for a relatively long time. Characterizations of catalysts (BET, XRD, Raman spectroscopy, TEM, H₂-TPR, O₂-TPD, XPS, TG-MS and SO₂-DRIFTS) were carried out to reveal the mechanism of Co modification on the redox ability, SO₂ resistance and resultant mercury oxidation removal performance of catalyst. It was found that an interaction of Ce with Co promoted the dispersion of CeO₂, increased chemisorbed oxygen concentration, and improved the oxygen storage capacity and the reducibility of catalyst, which was beneficial to the improvement of Hg⁰ oxidation removal. Hg⁰ would adsorb onto the catalyst and react with surface active oxygen species replenished by gas-phase O₂ to be oxidized via Mars-Maessen mechanism. SO₂ consumed the surface active oxygen species and resulted in the reduction of Ce⁴⁺ to Ce³⁺, which induced the deactivation of catalyst. The introduced Co in CeO₂-TiO₂ catalyst exerted the function of protecting Ce⁴⁺ from being poisoned by SO₂ and thus promoted the sulfur resistance and Hg⁰ removal performance of the catalyst in the presence of SO₂.     

300kVA电动车组高温超导变压器电流引线与套管的结构设计

根据300kVA/25000V/866V电动车组高温超导变压器的绝缘和漏热要求,在理论优化设计的基础上,对电流引线与套管的结构进行再设计并使之工程实现。     

非线性转子-机匣系统的分岔行为研究

建立了一类非线性转子-机匣系统的碰摩模型.应用数值分析的方法对其进行研究,得到了不同参数变化下系统响应随转速变化的分岔图,分析了系统参数变化对分岔过程的影响,并作出了在相应参数状态和特定转速下的Poincare截面图,揭示系统参数变化对非线性碰摩转子-机匣系统分岔特性的影响.     

Highly Fluorinated and Crosslinkable Dendritic Polymer for Photonic Applications

Summary: A novel crosslinkable dendritic polymer has been synthesized by the thermal polymerization of peripheral aryl trifluorovinyl ether moieties of a highly fluorinated dendrimer. The resulting perfluorocyclobutane(PFCB)‐containing dendritic polymer exhibited excellent processability, low optical loss (0.36 dB · cm⁻¹ at 1 310 nm with 1% dye doping), high thermal stability, and good solvent resistance for waveguide‐based photonic applications.

Structure of the crosslinkable fluorinated dendrimer synthesized.     

螺旋管内气-液两相流截面含气率试验研究和理论模型

１前言关于螺旋管内气－液两相截面含气率的预报是一个重要的课题。即使只考虑平均截面含气率,也有气液两相间的滑移、各相流速和气相沿流通截面的不均匀分布等影响因素。查阅有关文献［１,２］,对螺旋管内气－液两相截面含气率的研究还很不够。因此,本文重点从二方面进行了研究。首先借助快速关闭球阀法,得出三根不同螺旋管平均截面含气率的试验测定结果,考查了螺旋升角和螺旋直径对其产生的影响;其次,按不同流型,依据“分相动量模型”和“漂移流率模型”、得出计算螺旋管内主要流型平均截面含气率的经验关系式。本文研究对象：三…     

An Integral Algorithm for Numerical Integration of One-Dimensional Additive Colored Noise Problems

We present an integral-closed algorithm for solving a Langevin equation driven by an additive colored noise. Both the mean first passage time in a bistable system and the diffusion current in a titled periodic potential are calculated and the comparison with existing algorithms is carried out. The dependence of the numerical results on the time steps is studied. Our algorithm is shown to have high accuracy and stability.     

Asymptotic boundary and nonexistence of traveling waves in a discrete diffusive epidemic model

ABSTRACT

In this paper, we establish the asymptotic boundary of traveling waves (first-component) in a discrete diffusive epidemic model, whose existence is well-known. Meanwhile, we derive the nonexistence of traveling wave solutions with non-positive wave speed. We solve two open problems left in two papers [Fu et al., Nonlinear Convex A. 17 (2016), pp. 1739–1751; Wu, J. Differential Equations 262 (2017), pp. 272–282].