混业经营:我国金融体制结构性选择的基本方向

随着全球金融交易技术进步，信息处理和传输手段改进，金融自由化和金融活动全球一体化趋势的不断加强，越来越多的国家纷纷放弃原先的金融分业管制政策，越来越多金融机构热衷于兼并收购和多元化经营，金融日益融入国际金融市场体系的中国，自然也不能置之度外而独善其身。

如何进行DSP算法解码

当讨论利用DSP结构进行算法解码时,必须将视野扩展到最终消费者.只有这样才能更好地了解消费者的决策过程及购买模式.一般说来,消费者的主要选择标准应包括一系列的基本技术特性,比如杜比音频解码和DVD视频支持.此外,一些审美因素和比较新颖的特性也会在决策考虑之列.考虑到这些因素,可编程引擎应该是半导体供应商最佳的结构性方案.有了可编程特性,整个系统才可以有多种形式供选择,以满足不同消费者的偏好和特殊要求.

Effects of surface physicochemical properties on NH_3-SCR activity of MnO_2 catalysts with different crystal structures

α‐,β‐,δ‐,andγ‐MnO2nanocrystals are successfully prepared.We then evaluated the NH3selective catalytic reduction(SCR)performance of the MnO2catalysts with different phases.The NOx conversion efficiency decreased in the order:γ‐MnO2>α‐MnO2>δ‐MnO2>β‐MnO2.The NOx conversion with the use ofγ‐MnO2andα‐MnO2catalysts reached90%in the temperature range of140–200°C,while that based onβ‐MnO2reached only40%at200°C.Theγ‐MnO2andα‐MnO2nanowire crystal morphologies enabled good dispersion of the catalysts and resulted in a relatively high specific surface area.We found thatγ‐MnO2andα‐MnO2possessed stronger reducing abilities and more and stronger acidic sites than the other catalysts.In addition,more chemisorbed oxygen existed on the surface of theγ‐MnO2andα‐MnO2catalysts.Theγ‐MnO2andα‐MnO2catalysts showed excellent performance in the low‐temperature SCR of NO to N2with NH3.

Tuning the product selectivity of SAPO-18 catalysts in MTO reaction via cavity modification

The AEI cavity of SAPO-18 catalyst was modified with zinc cations with the conventional ion exchange procedure.The cavity modification effectively tunes the product selectivity,and shifts the products from mainly propylene to comparable production of ethylene and propylene in methanol to olefin(MTO)reaction.The incorporation of zinc ions and the generation of bicyclic aromatic species in the AEI cavity of SAPO-18 catalysts introduce additional diffusion hindrance that exert greater influence on the relatively bulky products(e.g.propylene and higher olefins),which increase the selectivity to small-sized products(e.g.ethylene).It appears that the incorporated zinc cations facilitate the generation of lower methylbenzenes which promote the generation of ethylene.The cavity modification via incorporating zinc ions effectively tunes the product selectivity over SAPO molecular sieves with relatively larger cavity,which provides a novel strategy to develop the potential alternative to SAPO-34 catalysts for industrial MTO reaction.

New development in Fe/Co catalysts:Structure modulation and performance optimization for syngas conversion

C1 chemistry is the essence of coal chemistry and natural gas chemistry. Catalytic methods to efficiently convert C1 molecules into fuels and chemicals have been extensively studied. Syngas（CO ＋H_2） conversion is the most important industrial reaction system in C1 chemistry, and Fe and Co catalysts, two major industrial catalysts, have been the focus of fundamental research and industrial application. In the last decade, considerable research efforts have been devoted to discoveries concerning catalyst structure and increasing market demands for olefins and oxygenates. Since the development of efficient catalysts would strongly benefit from catalyst design and the establishment of a new reaction system, this review comprehensively overviews syngas conversion in three main reactions, highlights the advances recently made and the challenges that remain open, and will stimulate future research activities. The first part of the review summarizes the breakthroughs in Fischer-Tropsch synthesis regarding the optimization of activity and stability, determination of the active phase, and mechanistic studies. The second part overviews the modulation of catalytic structure and product selectivity for Fischer-Tropsch to olefins（FTO）. Catalysts designed to produce higher alcohols, as well as to tune product selectivity in C1 chemistry, are described in the third section. Finally, present challenges in syngas conversion are proposed, and the solutions and prospects are discussed from the viewpoint of fundamental research and practical application. This review summarizes the latest advances in the design, preparation, and application of Fe/Co-based catalysts toward syngas conversion and presents the challenges and future directions in producing value-added fuels.

Enhanced stability of highly-dispersed copper catalyst supported by hierarchically porous carbon for long term selective hydrogenation

Copper based catalysts have high potential for the substituent of noble-metal based catalysts as their high selectivity and moderate activity for selective hydrogenation reaction;however,achieving further high catalytic stability is very difficult.In this work,the carbonization process of Cu-based organic frameworks was explored for the synthesis of highly-dispersed Cu supported by hierarchically porous carbon with high catalytic performance for selective hydrogenation of 1,3-butadiene.The porous hierarchy of carbon support and the dispersion of copper nanoparticles can be precisely tuned by controlling the carbonization process.The resultant catalyst carbonized at 600°C exhibits a rather low reaction temperature at 75°C for 100%butadiene conversion with 100%selectivity to butenes,due to its reasonable porous hierarchy and highly-dispersed copper sites.More importantly,unprecedentedly stability of the corresponding Cu catalyst was firstly observed for selective 1,3-butadiene hydrogenation,with both 100%butadiene conversion and 100%butenes selectivity over 120 h of reaction at 75°C.This study verifies that a simply control the carbonization process of metal organic frameworks can be an effective way to obtain Cu-based catalysts with superior catalytic performance for selective hydrogenation reaction.

Study on Collision Between Two Ships Using Selected Parameters in Collision Simulation

In the present analysis, several parameters used in a numerical simulation are investigated in an integrated study to obtain their influence on the process and results of this simulation. The parameters studied are element formulation, friction coefficient, and material model. Numerical simulations using the non-linear finite element method are conducted to produce virtual experimental data for several collision scenarios. Pattern and size damages caused by collision in a real accident case are assumed as real experimental data, and these are used to validate the method. The element model study performed indicates that the Belytschko-Tsay element formulation should be recommended for use in virtual experiments. It is recommended that the real value of the friction coefficient for materials involved is applied in simulations. For the study of the material model, the application of materials with high yield strength is recommended for use in the side hull structure.

Damage Detection of Offshore Jacket Structures Using Frequency Domain Selective Measurements

The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitoring. In efforts to fulfill this task, concept of the minimum rank perturbation theory has been utilized. The present article introduces a promising methodology to select frequency points effectively. To achieve this goal, modal strain energy ratio of each member was evaluated at different natural frequencies of structure in order to identify the sensitive frequency domain for damage detection. The proposed methodology opens up the possibility of much greater detection efficiency. In addition, the performance of the proposed method was evaluated in relation to multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform, and the results proved to be satisfactory utilizing the proposed methodology.

Hamiltonian Characterization for Dipolar Coupled Spin Systems

Measuring the Hamiltonian of dipolar coupled spin systems is usually a difficult task due to the high complexity of their spectra. Currently, molecules with unknown geometrical structure and low symmetry are extremely tedious or impossible to analyze by sheer spectral fitting. We present a novel method that addresses the problem of spectral analysis and report experimental results of extracting, by spectral fitting, the parameters of an oriented 6-spin system with very low symmetry in structure, without using apriori knowledge or assumptions on the molecular geometry or order parameters. The advantages of our method are achieved with the use of a new spectral analysis algorithm non-assigned frequency optimization of NMR spectra （NAFONS） and by the use of simplified spectra obtained by transition selective pulses. This new method goes beyond the limit of spectral analysis for dipolar coupled spin systems and is helpful for related fields, such as quantum computation and molecular structure analysis.

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose （cellulose I） can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose （cellulose Ⅱ ） can be completely selectively oxidized. In the present work, natural cellulose pulp was treated with NaOH solution, which concentration is lower than 20 wt%. The alkaline celluloses obtained were oxidized by TEMPO - NaOCI - NaBr system and the factors which influence the selective oxidation reaction rate have been investigated. The structure of the oxidized products has been characterized by Fourier transform-infrared （FTIR）, nuclear magenatic resonace （NMR） and wide angle X-ray diffraction （WAXD） methods, and their adsorption properties for Cu^2＋ and Cd^2＋ in aqueous solutions have been preliminarily examined. The results show that after the alkaline treatment, the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8, the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing. The alkaline treatment has a great effect on the crystal structure of natural cellulose, but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation. The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.

Tunable attenuator based on polymer microstructured optical fibers

Based on polymer microstructured optical fibers (PMOF) and selective liquid crystal injection technology, a novel tem- perature control tunable attenuator is designed theoretically in this paper. In our experiments, PMMA microstructured optical fibers with high performance are drawn successfully and the selective injection of liquid crystal 5CB into micro- holes is realized. The tunable attenuator is fabricated with an extinction ratio of over 60dB, which agrees well with the design.

Selectively constructing sandwich-like heterostructure of CdS/PbTiO_(3)/TiO_(2)to improve visible-light photocatalytic H_(2)evolution

Fast migration and efficient spatial separation of photogenerated charges in photocatalytic materials are indispensable to efficient solar water splitting reactions.Here,we construct a three-phase heterostructure of CdS/PbTiO_(3)/TiO_(2)by selectively depositing CdS and TiO_(2)at oppositely poled crystal facets of PbTiO_(3)using single-domain ferroelectric PbTiO_(3).The heterostructure has matching band edge alignments and strong interfacial connections at different moieties.The heterostructure combines the interfacial electrical and ferroelectric fields because of their peculiar microstructures,which provide a strong driving force throughout the whole bulk to separate photogenerated charges.Almost two orders of magnitude improvement of visible-light-driven photocatalytic H_(2) production has been realized in CdS/PbTiO_(3)/TiO_(2)compared with bare PbTiO_(3)/TiO_(2),showing the efficiency of charge separation in the heterostructure.The idea of combining ferroelectrics with potential light capture semiconductor provides a paradigm to accurately design charge migration pathways,bringing a step closer to efficient solar water splitting.

The geography of introgression in a patchy environment and the thorn in the side of ecological speciation

When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic structure of selected traits/loci tends to coincide with habitat variables （producing Genetic-Environment Association or GEA）, genetic differentiation at neutral loci unlinked to any selected locus rather depends on geographic connectivity at a large scale （e.g. Isolation- By-Distance or IBD）, although these loci often display GEA at a small scale. This discrepancy has been repeatedly taken as evi- dence for parallel primary divergence driven by local adaptation. We argue that this interpretation needs to be addressed more thoroughly by considering the alternative hypothesis that speciation was initiated in allopatry and secondary introgression has subsequently erased the signal of past differentiation at neutral loci. We present a model of neutral introgression after secondary contact in a mosaic hybrid zone, which describes how GEAs dissipate with time and how neutral variation self-organizes accord- ing to the environmental and geographic structures. We show that although neutral loci can be affected by environmental selection they are often more affected by history and connectivity： the neutral structure retains the initial geographic separation more than it correlates with the environment during the colonization and introgression phases, and then converges to a migration-drift balance, the most frequent outcome of which is GEA at a local scale but IBD at a large scale. This is the exact pattern usually attributed to parallel ecological speciation. Introgression is heterogeneous in space and depends on the landscape structure （e.g. it is faster in small patches, which are more impacted by immigration）. Furthermore, there is no directionality in the association and it is possi- ble to observe reversed GEAs between distant regions. We argue that the history of differentiation should ideally be reconstructed with selected loci or neutral loci linked to them, not neutral ones, and review some case studies for which the hypothesis of a long co-existence of co-adapted genetic backgrounds might have been refuted too hastily [Current Zoology 59 （1）： 72-86, 2013].

Asymmetric construction of all-carbon quaternary stereocenters in the total synthesis of natural products

Structure units containing all-carbon quaternary stereogenic center are found in many bioactive natural products. However, enantioselective construction of this type of structure units has been a formidable challenge for synthetic community due to the steric hindrance enforced by all-carbon quatemary stereocenters. In this review, we present the achievements made by Chinese scientists in the area of asymmetric synthesis of all-carbon quaternary stereocenters in natural products during the past two years.

Bimetallic phthalocyanine heterostructure used for highly selective electrocatalytic CO_(2) reduction

Heterogeneous molecular catalysts,such as metal phthalocyanines,are efficient electrocatalysts for CO_(2) reduction reaction(CO_(2)RR).However,the rational design and synthesis of a molecular catalyst-based heterostructure for CO_(2)RR remains challenging.Herein,we developed a crystalline bimetallic phthalocyanine heterostructure electrocatalyst(CoPc/FePc HS),which achieved an excellent CO_(2)-to-CO conversion efficiency(99%)and outstanding long-term stability after 10 h of electrocatalysis.Density functional theory calculations revealed that the enhancement of CO_(2)RR performance could be attributed to the distinct electron transfer pattern between FePc and CoPc.The heterostructural engineering in molecular catalysts would inspire a unique approach for improving CO_(2)RR performance.

A facile one-pot synthesis of supercubes of Pt nanocubes

A facile one-pot synthetic strategy is developed to prepare high-quality Pt supercubes. The as-synthesized Pt supercubes are composed of the uniform Pt nanocubes arranged in a primitive cubic structure. The shape and size of the Pt superparticles are readily tuned by varying the structures of pyridyl-containing ligands used in the synthesis. The co-presence of CO and nitrogen-containing ligands is critical to the formation of Pt supercubes. While CO molecules play an important role in the synthesis of Pt nanocube, introducing nitrogen-containing ligands is essential to the successful assembly of those nanocubes into Pt supercubes. Our systematic studies reveal that the electrostatic attraction between positively charged ligands and nega- tively charged Pt nanocubes is the main driving force for the assembly of Pt nanocubes into supercubes. More importantly, the ligands within the Pt supercubes are readily removed at relatively low expected to exhibit unique size-selective catalysis. temperature to yield surface-clean supercubes which are

In situ construction of amorphous hierarchical iron oxyhydroxide nanotubes via selective dissolution-regrowth strategy for enhanced lithium storage

The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries(LIBs)with high energy density.However,their commercialization is greatly hindered by insufficient rate capability and cyclability.Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties.Herein,we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional(1D)hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires.Benefiting from the improved electron/ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level,the graphene-modified amorphous hierarchical FeOOH nanotubes(FeOOH-NTs)display high rate capability(~650 mA h g^−1 at 2000 mA g^−1)and superior long-term cycling stability(463 mA h g^−1 after 1800 cycles),which represents the best cycling performance among the reported FeOOH-based materials.More importantly,the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process,in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles.The present strategy is also a general method to prepare various metal(such as Fe,Mn,Co,and Cu)oxides/oxyhydroxides with 1D hierarchical nanostructures.

Correlation between Chemical Structure and Biological Activity of Host-Selective Plant Pathogen Mycotoxins

Toxin, one of the most important factors of plant fungal disease, has attracted much attention of many academicians who have been studying pathogen mycotoxin in deep research. The paper summarized chemical structures of some host-selective plant pathogen mycotoxins discovered in recent years and the correlation between biological activity and chemical structure of toxin.