Analysis of composition homogeneity and polarization orientation of PZT submicron fibers by micro-Raman spectroscopy

Micro-Raman spectroscopy is a convenient tool to probe individual objects with a feature size on the submicron scale. The phase, composition, and orientation of Pb(Zr,Ti)O₃ fibers fabricated via hydrothermal processing have been characterized by this technique, with the working principles given in the paper. It is shown that the prepared PZT submicron fibers are of a tetragonal pervoskite phase, with Zr/(Zr + Ti) varying from 0.05 to 0.25. The spontaneous polarization has been confirmed to be along the length direction and one of its {1 0 0} planes parallel to the substrate plane.     

1D ZnFe2O4 nanorods coupled with plasmonic Ag,Ag2S nanoparticles and Co-Pi cocatalysts for efficient photoelectrochemical water splitting

Improving the absorption of visible light, accelerating the separation of carries and reducing the recombination of electron-hole pairs are critical to enhance photoelectrochemical (PEC) performance of ZnFe₂O₄. Herein, the ZnFe₂O₄/Ag/Ag₂S films are firstly prepared with a photocurrent density of 0.91 mA/cm² at 1.23 V vs. RHE, which is 9.10 times higher than that of pristine ZnFe₂O₄ (0.10 mA/cm² at 1.23 V vs. RHE). On the basis, Co-Pi cocatalyst is deposited on ZnFe₂O₄/Ag/Ag₂S to further optimize PEC performance of ZnFe₂O₄, the photocurrent density of ZnFe₂O₄/Ag/Ag₂S/Co-Pi is 1.18 mA/cm² at 1.23 V vs. RHE. The improved PEC performance of ZnFe₂O₄/Ag/Ag₂S/Co-Pi films could be attributed to: (i) fast transmission of electron-hole pairs owing to 1D ZnFe₂O₄ NRs; (ii) surface plasmon resonance (SPR) effect of Ag nanoparticles; (ⅲ) visible light absorption is improved by sensitization of Ag₂S nanoparticles; (ⅳ) Co-Pi cocatalyst decreases the recombination of electron-hole pairs by capturing holes. This work provides new insights for metal plasmas, sensitizers and cocatalysts synergistically modify photoanodes for efficient PEC water splitting.     

应用等张模式测定人体单关节肌群功率发展与保持能力的方法学研究

人体肌肉功率的发展与保持能力在完成生产劳动、日常体力活动和体育运动中具有重要的作用.本文以12名健康普通大学生为研究对象,运用模拟仿真测试评价训练系统( BTE PrimusRS)的等张测量模式来探讨人体单关节肌群功率发展与保持能力的测评方法.结果表明BTE PrimusRS系统能客观、准确地评价人体单关节肌群功率发展与保持能力的水平;此等张测试模式下,50％等长峰值肌力(或力矩)的阻力负荷设置较为合理;等长峰值肌力应采用非爆发式静力性测量模式获得.     

烟气脱汞技术研究现状与展望

重金属汞的危害性决定了烟气脱汞的必要性,尤其在污染物超低排放的背景下。首先分别从常规烟气净化装置脱汞、碳基吸附剂脱汞、矿物类吸附剂脱汞以及金属催化剂脱汞等四个方面综述了烟气脱汞技术研究现状,重点讨论了各种烟气脱汞技术特点以及吸附剂改性的反应机理。最后,分别从协同脱汞、纳米吸附剂脱汞以及可再生脱汞等三个方面对未来脱汞技术进行了展望,该三个方面主要分别涉及了多污染物控制排放、提高脱汞效率以及降低脱汞技术应用成本。期望为烟气脱汞技术的进一步开发与应用提供参考。     

Photocatalytic reduction of chromium and oxidation of organics by polyoxometalates

The photocatalytic reduction of Cr(VI) to the less toxic Cr(III) is presented in the presence of the polyoxometalates (POM) PW₁₂O₄₀³⁻ or SiW₁₂O₄₀⁴⁻ as photocatalyst and an organic substrate (salicylic acid or propan-2-ol) as electron donor. Cr(VI), as dichromate, is reduced to Cr(III), according to the 6:1 stoichiometry of PW₁₂O₄₀⁴⁻ versus Cr₂O₇²⁻ indicated from experiments in the dark. Increase of POM or salicylic acid (SA) concentration accelerates, till a saturation value, both the reduction of metal and the oxidation of the organic, suggesting that these two conjugate reactions act synergistically. The photocatalytic action of POM is not so important in the case of highly concentrated solutions of organics that exhibit direct photochemical reduction of Cr(VI), i.e. propan-2-ol (i-prOH), while it becomes important at low concentrations of i-prOH, especially for organics that do not react directly photochemically with Cr(VI), such as SA. Increase of Cr(VI) concentration enhances consumption of SA and Cr(VI) till an optimum value, due to inner filter effect. The method is suitable for a range of chromium concentration from 5–100 ppm achieving complete reduction of Cr(VI) to Cr(III) up to non-detected traces (>98%). The presence of oxygen does not influence the efficiency of SA and Cr(VI) consumption. In contrast to the semiconductor-based heterogeneous photocatalysis, the POM-based homogeneous process seems superior in the frame that: (i) it remains catalytic throughout illumination by providing more active sites and (ii) among the two POM used, the one that is more efficient in the degradation of the organic, that is PW₁₂O₄₀³⁻ compared to SiW₁₂O₄₀⁴⁻, is also more efficient in reducing Cr(VI), due to a kinetic effect, and a compromise is not needed.     

焦油主要组份在循环灰下催化裂解的实验研究

在以循环流化床锅炉循环灰为热载体，部分气化产生的半焦为锅炉燃料，煤气为燃气轮机燃料的煤的部分气化联合循环中，降低焦油产率，提高煤气产率是一个技术关键，以焦油的两种主要组份苯和甲苯为研究对象，利用固定床实验台实验研究了一种混煤形成的循环灰条件下的裂解反应特性，测定了裂解反应动力学参数，探讨了循环灰对焦油裂解的催化机理。实验结果表明，与石英砂条件相比，循环灰极大地促进了焦油的裂解程度，气态裂解产物总量     

Blending response surface methodology and principal components analysis to match a target product

Highly trained sensory panels have long been used to evaluate food products on perhaps dozens of attributes. Principal components analysis is one of a number of multivariate data analysis techniques commonly used in analyzing sensory panel data. More recently, response surface designs have been used to direct the creation of product prototypes so that the effects of ingredient levels and/or processing conditions can be modeled. This paper will discuss how the two methodologies have been used together in projects where the goal is to identify ingredient levels and/or processing conditions that best match a target product's sensory profile. Some unique problems arise when analyzing and interpreting the results of response surface models when the number of responses is quite large. This paper will explain how some of these problems have been addressed through the detailed discussion of the development of a cost reduced product. Six ingredients were systematically varied in a response surface design to create 48 prototypes. The prototypes and the target product were then measured on 33 sensory attributes. Design selection, data collection, response surface modeling, rotated principal components analysis and the use of both desirability and distance functions to identify ingredient level combinations that meet the product development objectives will be discussed in detail using the data analyses from this project. Recommendations for next steps in the product development process will also be given.     

普通强度混凝土高性能化的研究

普通强度等级的混凝土在结构形成过程中,由于泌水与离析,产生内分层与外分层.采用5～10mm的豆石取代15～20%的粗骨料,调整其级配,降低空隙率,并以复合超细粉取代混凝土中的部分水泥,从而降低单方混凝土的用水量和水泥浆用量,使普通强度等级的混凝土性能提高,使用寿命延长,这称之为普通混凝土高性能化.试验证明,高性能化后的普通混凝土,与原来的基准混凝土相比,强度和流动性大体相同,但泌水量明显降低,结构粘度提高,混凝土的结构均匀性得到明显改善,C1-扩散系数大大降低,使用寿命由原来的40年延长到70年,达到了高性能化.     

矿渣掺量对高强高性能混凝土强度和耐久性影响的试验研究

研究矿渣掺碍对于高强高性能混凝土性能的影响。水胶比为０．２８,矿渣掺量达４０％,可以配制出早期,后期强度无高于不掺矿渣,而水泥用量高达６００ｋｇ／ｍ＾３的纯水泥混凝土的相应强度,这种配合比的混凝土２８天强度在８７ＭＰａ以上;并且流动性好,可以满足泵送需要。