垃圾气化分析及其对中国实现碳中和与无废城市建设的贡献

气化是实现化学利用碳资源(尤其是煤)生产化学品和燃料的关键工艺.目前,全球拥有超过272套气化装置,主要应用于煤化工,尤其在中国.由于在一个化工厂通过技术集成达到工业规模的集中生产可实现减少二氧化碳排放并促进碳密集型行业的循环经济,如废物管理、化学和交通行业,因此,近年来全球对垃圾气化的兴趣日益浓厚,尤其是那些在煤气化...     

ANALYSIS OF PHOTOTRANSFORMATION INTERMEDIATES IN THE PATHWAY FROM THE RED-ABSORBING TO THE FAR-RED-ABSORBING FORM OF AVENA PHYTOCHROME BY A MULTICHANNEL TRANSIENT SPECTRUM ANALYZER

Phototransformation of the red-absorbing form of phytochrome (Pr) to the far-red-absorbing form (Pfr) was followed with a custom-built transient spectrum analyzer. Large phytochrome, which consisted of approximately 120000-dalton monomers, was immunopurified or conventionally purified from etiolated oat (Avena sativa L., cv. Garry) shoots. Phototransformation was initiated by exciting Pr with a 115-mJ, 600-ns half-width, 655-nm laser pulse. Absorption spectra were recorded on a microsecond time scale at predetermined times after the flash. It has been reported earlier that flash excitation of large oat Pr produces a transformation intermediate with maximum absorbance near 700 nm in a difference spectrum and that this intermediate decays by two kinetically distinct reactions. Difference spectra for these two reactions are indistinguishable. Both show bleaching centered at 690 nm with no detectable associated absorbance increase between 570 and 830 nm. Subsequent appearance of absorbance at 724 nm, which presumably but not necessarily represents the appearance of Pfr, had earlier been shown to occur by two kinetically distinct reactions for large oat phytochrome. Data presented here indicate in addition the occurrence of a third, slower reaction. Difference spectra for the two faster reactions are indistinguishable, both with maxima near 728 nm and minima near 650 nm. The difference spectrum for the slowest component, however, was qualitatively different exhibiting a maximum near 722 nm with no corresponding minimum. About 15-20% of the absorbance increase at 724 nm occurred by this slowest reaction, which exhibited a half-life of 3 s at 25°C and a Q₁₀ of 1.2 for immunopurified and 1.5 for conventionally purified phytochrome. The percentage occurring by this reaction was independent of temperature over the range studied (1-25dEC). For immunopurified phytochrome the enthalpy of activation, Gibbs free energy of activation, and entropy of activation of this slowest reaction were found to be about lOkJ-mol^-1, 75kJ.mol^-1, and -220 J.mol^-1 K^-1, respectively, and for conventionally purified phytochrome 25kJ.mol^-1, 75kJ.mol^-1and —170 J.mol^-1 K^-1, respectively. The thermodynamic characteristics of this reaction indicate that it may involve a significant ordering of the protein moiety as it transforms to Pfr.     

Novel Method of Preparation of Monolithic Columns for Fast Separation by γ-Ray Irradiation

A porous monolithic sol-gel column with the solution of methacryloxypropyltrimethoxysilane in toluene with an acid catalyst was prepared in the presence and absence of sodium dodecyl sulfate. In situ polymerization was carried out byγ-ray irradiation within the capillary. Theγ-radiation-initiated synthesis could generate radicals directly on the monomer avoiding use of any initiator. The chromatographic behavior of the capillary monolithic columns were studied in the modes of CEC, p-CEC and low pressure-driven separation, all the tests exhibited reversed-phase character. It provided a viable alternative to either thermally initiated or photo polymerization method for the preparation of monolithic columns.     

四碘化钛-三異丁基铝催化体系制备顺式-1,4-聚丁二烯——Ⅰ.催化剂的活性和聚合物的性质

研究了丁二烯在苯中有四碘化钛-三异丁基铝催化剂的存在下的聚合。发现这一催化体系的活性取决于Al/Ti比和聚合温度。对每一四碘化钛用量出现一具有最高活性的“临界Al/Ti此”;低于这一Al/Ti比,活性完全消失;高于这一Al/Ti比则活性逐渐降低(图2)。 增加Al/Ti可以减慢聚合速度而不影响最终转化率(图3);因此,可以利用Al/Ti来控制这一聚合反应以防止反应混合物的积热现象(图4)。 这一催化体系的优点是不论在任何条件下,包括催化剂组成(例如Al/Ti)和聚合条件(例如温度),聚合物都不合凝胶,而顺-1,4-结构含量总能在90％以上(表2)。 聚合物的分子量取决于两个主要因素:四碘化钛用量和聚合温度;增加四碘化钛用量和升高聚合温度都降低分子量(图5和图6)。Al/Ti对分子量的影响则不甚明显(图6)。 用这种催化剂制得的顺-1,4-聚丁二烯的分子量分布很窄(图7);因此,虽然这是一个非均相催化体系,它的活性中心可能比较单纯,大概不会含有多种活性中心。     

在铅板里发生的电子光子簇射

关于把电子光子簇射的实验与理论相比较的工作,还是非常的少。我们在用云雾室研究穿透簇射和星芒的过程中,也获得一些电子光子簇射的照片。从中选择了适合于研究条件的一部分,加以分析,与理论作比较。     

A Comparison of Residual-stress Measurements Using Blind-hole, Abrasive-jet and Trepan-ring Methods

This article describes the results of residual-stress measurements which were made on an artillery-projectile metal part to determine whether the state of the stress could be a factor in promoting a failure that had occurred during ballistic test firing. An additional objective of the work was to evaluate the suitability of several different methods for measuring residual stresses by the performance of these measurements on the same metal part.     

Optical Properties of Zinc-Blende InGaN/GaN Quantum Well Structures and Comparison with Experiment

Optical properties of zinc-blende InGaN/GaN Q W structures are investigated using the multiband effective-mass theory. The transition wavelength values at 300 K ranged from 440 to 570nm in the investigated range of the In composition and the well width. The theoretical wavelengths show reasonable agreement with the experimental results. The optical gain decreases with the increasing well width. This is mainly due to the reduction in the quasi-Fermi-level separation because the optical matrix element increases with the well width.     

Spectral Analysis of Social Networks to Identify Periodicity

Two key problems in the study of longitudinal networks are determining when to chunk continuous time data into discrete time periods for network analysis and identifying periodicity in the data. In addition, statistical process control applied to longitudinal social network measures can be biased by the effects of relational dependence and periodicity in the data. Thus, the detection of change is often obscured by random noise. Fourier analysis is used to determine statistically significant periodic frequencies in longitudinal network data. Two approaches are then offered: using significant periods as a basis to chunk data for longitudinal network analysis or using the significant periods to filter the longitudinal data. E-mail communication collected at the United States Military Academy is examined.     

Basis set limit binding energies of hydrogen bonded clusters

The utility of the recently developed extrapolation method to estimate the binding energies of weakly bound clusters at the basis set limit exploiting the similar basis set convergence behaviour of correlation energies of the monomer and cluster in correlated calculations (J. chem. Phys., 116, 5389 (2002)) was tested for small to medium (HF)_n and (H₂O)_n (n = 2–5) clusters using various correlation consistent cc-pVXZ (X= D,T,Q,5) basis sets containing different numbers of diffuse functions and 6–31G type basis sets at the MP2 and CCSD(T) level for which accurate basis set limits are available for comparison. It is shown that the basis set limit binding energies estimated by this extrapolation method with modest size of basis sets (cc-pVDZ/cc-pVTZ or 6–3 1 G(d,p)/6-3 IG(2df,2pd)) are much closer to the exact basis set limits than the estimates by commonly used X ^?3 extrapolation or counterpoise corrected binding energies, signifying the importance of this extrapolation method for the study of large weakly bound clusters. It is also shown that the inclusion of appropriate diffuse functions in the basis sets can significantly improve the accuracy of the estimated basis set limits by this extrapolation method. For (HF)_n clusters the MP2 and CCSD(T) basis set limits estimated by this extrapolation method with aug-cc-pVDZ and aug-cc-pVTZ basis sets are 18.4 (18.5) and 18.9 (18.9) for the dimer, 61.8 (62) and 63.2 (63) for the trimer, 113.5 and 114.7 (116) for the tetramer, and 155.2 and 156.3 (158) for the pentamer, respectively, with the values in parentheses representing the apparent basis set limits, with the numbers in units of kJ mol^?1. The corresponding results for (H₂O)_n clusters are 20.5 (20.5) and 20.6 (20.7) for (H₂O)₂, and 60.5 (61) and 60.1 (60) for (H₂O)₃, respectively.     

Periodic solutions of Wick-type stochastic Korteweg–de Vries equations

Nonlinear stochastic partial differential equations have a wide range of applications in science and engineering. Finding exact solutions of the Wick-type stochastic equation will be helpful in the theories and numerical studies of such equations. In this paper, Kudrayshov method together with Hermite transform is implemented to obtain exact solutions of Wick-type stochastic Korteweg–de Vries equation. Further, graphical illustrations in two- and three-dimensional plots of the obtained solutions depending on time and space are also given with white noise functionals.