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91.
超疏水涂膜的研究进展 总被引:5,自引:0,他引:5
超疏水涂膜以其独特的性能,在国防、工农业生产和日常生活中有着广泛的应用前景。但目前的制备技术制约了其在建筑外墙涂料等大型设施方面的应用。探索如何采用简单有效的方法构造和调控涂膜的双微观结构,从而获得性能持久优异的超疏水性涂膜,并有效应用于生产和生活的各个方面是这一领域研究的最终目标。本文就超疏水材料表面理论的发展和近几年来超疏水膜制备技术取得的新成果进行了概括,并指出制备超疏水涂膜存在的问题和发展方向。利用表面能极低的含氟材料,将溶胶-凝胶、相分离技术和自组装梯度功能等技术有机结合,获得适宜的表面粗糙度和微观构造,是实现超疏水涂膜工业化生产的可行途径。 相似文献
92.
磁铅石型复合氧化物LaNi_xCo_(1-x)Al_(11)O_(19+δ)催化剂上CH_4和CO_2重整反应的研究 总被引:3,自引:0,他引:3
考察了磁铅石型复合氧化物LaNi_(0.5)M_(0.5)Al_(11)O_(19 + δ) (M = Co, Fe, Mn, Cu)和LaNi_xCo_(1-x)Al_(11)O_(19+δ)催化剂在CH_4与CO_2重整制合成 气反应中的催化活性,并应用XRD,TPR,UV-DRS技术着重表征LaNi_xCo_(1-x)Al_ (11)O_(19+δ)催化剂的结构和性能。研究结果表明该系列催化剂具有相同的晶体 结构和相似的还原稳定性。对不同过渡金属取代的催化剂来说,以LaNi_(0.5)Co_ (0.5)Al_(11)O_(19+δ)催化剂具有最好的反应活性。而对于LaNi_xCo_(1-x)Al_ (11)O_(19+δ)系列催化剂,当x ≤ 0.375时,随x值的增大,催化活性明显提高, 但在0.375 ≤ x ≤ 1.0范围内,催化活性几乎保持不变。由此得到结论,对于此 反应来说,控制Ni量在0.375 ≤ x ≤ 0.50范围内比较合适。 相似文献
93.
Key aspects of the microenvironment surrounding the Fe center in the nitrosyl adduct of iron phthalocyanine, [Fe(Pc)(NO)], have been elucidated from the analysis of the Fe K-edge extended X-ray absorption fine structure (EXAFS) of the material adsorbed on the surface of a high area carbon electrode recorded in situ, in 0.5 M H(2)SO(4). Statistical best fits to the EXAFS data place the Fe center in a five-coordinated square pyramidal configuration shifted away from the Pc plane toward the axially bound NO bent at an angle of ca. 40 degrees with respect to the normal to the Pc plane. This environment is analogous to that of Fe in the nitrosyl adduct of crystalline [Fe(TPP)], where TPP = meso-tetraphenylporphyrinato(2-), determined from X-ray diffraction. 相似文献
94.
Abstract —Using semi-empirical analytic formulas for the transmitted and scattered ultraviolet spectral irradiance at the ground (Green, A. E. S., T. Sawada and E. P. Shettle, Photochem. Photobiol. 19 , 251–259, 1974), we calculate erythema dose rates and daily erythema doses. Results are illustrated graphically, and for the purpose of photobiological applications are given in terms of approximate analytic forms, with parameters presented in tabular form. The relative erythema data assembled by W. W. Coblentz and R. Stair (U.S. Bureau of Standards J. Res. 12 , 13–14, 1934), as fit by an analytic form, is taken as a standard spectrum in our calculations. Other forms of erythema spectra are also compared. 相似文献
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97.
The contribution of the Institute for Reference Materials and Measurements to the certification of the B, Cd, Cu, Mg, and Pb content of a synthetic water sample used in Comparison 12 of the International Measurement Evaluation Programme (IMEP-12) is described. The aim of the IMEP programme is to demonstrate objectively the degree of equivalence and quality of chemical measurements of individual laboratories on the international scene by comparing them with reference ranges traceable to the SI (Système International d'Unités). IMEP is organized in support of European Union policies and helps to improve the traceability of values produced by field chemical measurement laboratories. The analytical procedure used to establish the reference values for the B, Cd, Cu, Mg, and Pb content of the IMEP-12 sample is based on inductively coupled plasma-isotope-dilution mass spectrometry (ICP-IDMS) applied as a primary method of measurement. The measurements performed for the IMEP-12 study are described in detail. Focus is on the element boron, which is particularly difficult to analyze by ICP-MS because of potential problems of low sensitivity, high mass discrimination, memory effects, and abundance sensitivity. For each of the certified amount contents presented here a total uncertainty budget was calculated using the method of propagation of uncertainties according to ISO (International Organization for Standardization) and Eurachem guidelines. For all investigated elements with concentrations in the low micro g kg(-1) and mg kg(-1) range (corresponding to pmol kg(-1) to the high micro mol kg(-1) level), SI-traceable reference values with relative expanded uncertainties ( k=2) of less than 2 % were obtained. 相似文献
98.
聚醚醚酮酮结晶度研究刘天西,王尚尔,张宏放,莫志深(中国科学院长春应用化学研究所高分子物理联合开放研究实验室长春130022)那辉,王军佐,吴忠文(吉林大学化学系长春)关键词聚醚醚酮酮,广角X射线衍射,结晶度新型特种工程塑料聚醚醚酮酮(PEEKK)具... 相似文献
99.
Yiming Mo Yanfei Guan Pritha Verma Jiang Guo Mike E. Fortunato Zhaohong Lu Connor W. Coley Klavs F. Jensen 《Chemical science》2021,12(4):1469
With recent advances in the computer-aided synthesis planning (CASP) powered by data science and machine learning, modern CASP programs can rapidly identify thousands of potential pathways for a given target molecule. However, the lack of a holistic pathway evaluation mechanism makes it challenging to systematically prioritize strategic pathways except for using some simple heuristics. Herein, we introduce a data-driven approach to evaluate the relative strategic levels of retrosynthesis pathways using a dynamic tree-structured long short-term memory (tree-LSTM) model. We first curated a retrosynthesis pathway database, containing 238k patent-extracted pathways along with ∼55 M artificial pathways generated from an open-source CASP program, ASKCOS. The tree-LSTM model was trained to differentiate patent-extracted and artificial pathways with the same target molecule in order to learn the strategic relationship among single-step reactions within the patent-extracted pathways. The model achieved a top-1 ranking accuracy of 79.1% to recognize patent-extracted pathways. In addition, the trained tree-LSTM model learned to encode pathway-level information into a representative latent vector, which can facilitate clustering similar pathways to help illustrate strategically diverse pathways generated from CASP programs.Tree-structured long short-term memory neural model learns to understand the retrosynthesis design strategies from patent-extracted retrosynthetic pathway data. 相似文献
100.
A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscosity and density of the mixture increased, and as a result, the resonance frequency decreased correspondingly after TAL was mixed with the heated E. coli solution that contained endotoxin. Results showed that the frequency shift was linearly related to the logarithm of E. coli concentration in the range of 2.7x10(4)-2.7x10(8) cells/ml. The correlation coefficient was 0.996. This BAW-TAL method was compared with the standard pour plate counts (PPC) method. The proposed method was much more rapid and simpler for detection of E. coli than the traditional methods. 相似文献