关于美国治理污染土地超级基金制度的若干思考

日趋严重的环境问题成为制约经济发展和人们生活素质提高的一个重要因素,环境污染治理基金制度在土地污染治理和危险物质处理方面发挥着重要的作用,为我国解决相关问题提供了可供参考的途径和方法。本文从美国的超级基金法的产生和发展入手,探讨了美国超级基金制度在实践运行中的效果,提出了借鉴美国超级基金法应当注意的问题和相应的解决方案。

对美国超级基金法的一点思考

环境问题日趋严重,成为制约经济发展和人们生活水平提高的一个重要问题,环境保护基金制度作为解决环境问题的一种经济手段在国外发挥着重要的作用,为我国解决环境问题提供了一种途径。本文选择了从美国的超级基金法入手探讨了美国超级基金在实践中的成功与不足,进而提出了在构建中国的环境保护制度时应该注意的问题和相应的解决方案。

船舶溢油应急反应机制的资金保障制度研究

船舶溢油应急反应资金保障制度的缺失,直接影响到船舶溢油应急反应工作的开展和溢油应急反应能力的提高。本文在构建船舶溢油应急反应资金保障制度设想的同时,包括资金的来源、适用范围、资金的管理、申请及支付程序等,也考虑了船舶溢油应急反应专项基金与船舶油污责任强制保证制度、油污损害赔偿基金等制度的衔接。

论创设船舶溢油应急反应机制资金保障制度

我国在应急处理船舶溢油事故时，由于缺乏基金支持，导致事故发生后有关单位为快速启动溢油应急反应机制而付出的开支得不到及时补偿。船舶溢油应急反应资金保障制度的缺失，直接影响船舶溢油应急反应工作的开展和溢油应急反应能力的提高。构建船舶溢油应急反应机制资金保障制度的设想，应包括基金的来源、适用范围、基金的管理、申请及支付程序等。

Recent Advances in Transition Metal-Based Catalysts for Electrocatalytic Nitrate Reduction Reaction

The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalytic nitrate reduction reaction(eNO_(3)RR)has been widely studied for its advantages of being eco-friendly,easy to operate,and controllable under environmental conditions with renewable energy as the driving force.Transition metal-based catalysts(TMCs)have been widely used in electrocatalysis due to their abundant reserves,low costs,easy-to-regulate electronic structure and considerable electrochemical activity.In addition,TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction,the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity.Based on this,this review firstly discusses the mechanism as well as analyzes the two main reduction products(N_(2)and NH_(3))of eNO_(3)RR,and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism.Secondly,this review mainly focuses on the recent advances in the direction of eNO_(3RR)with four types of TMCs,Fe,Co,Ni and Cu,and unveils the interfacial modulation strategies of Fe,Co,Ni and Cu catalysts for the activity,reaction pathway and stability.Finally,reasonable suggestions and opportunities are proposed for the challenges and future development of eNO_(3)RR.This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts(NMCs)for eNO_(3)RR.

Microstructure and shear strength of reactive brazing joints of TiAl/Ni-based alloy

Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated. The interfacial microstructure and shear strength of the joints were studied. According to the experimental observations, the molten interlayer reacts vigorously with base metals, forming several continuous reaction layers. The typical interfacial microstructure of the joint can be expressed as GH99/（Ni,Cr）ss（γ）/TiNi（β2）＋TiNi2Al（τ4）＋Ti2Ni（δ）/δ＋Ti3Al（α2）＋Al3NiTi2（τ3）/α2＋τ3/TiAl. The maximum shear strength is 258 MPa for the specimen brazed at 1000°C for 10 min. Higher brazing temperature or longer brazing time causes coarsening of the phases in the brazing seam and formation of brittle intermetallic layer, which greatly depresses the shear strength of the joints.

Effects of resistin-like molecule β over-expression on gastric cancer cells in vitro

AIM: To investigate the effects of resistin-like molecule β (RELMβ) over-expression on the invasion, metastasis and angiogenesis of gastric cancer cells. METHODS: Human RELMβ encoding expression vec tor was constructed and transfected into the RELMβ lowly-expressed gastric cancer cell lines SGC7901 and MKN-45. Gene expression was measured by Western blotting, reverse transcription polymerase chain reaction (PCR) and real-time quantitative PCR. Cell proliferation was measured by 2-(4,5-dimethyltriazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetry, colony formation and 5-ethynyl-20-deoxyuridine incorporation assays. The in vitro migration, invasion and metastasis of cancer cells were measured by cell adhesion assay, scratch assay and matrigel invasion assay. The angiogenic capabilities of cancer cells were measured by tube formation of endothelial cells. RESULTS: Transfection of RELMβ vector into SGC-7901 and MKN-45 cells resulted in over-expression of RELMβ, which did not infl uence the cellular proliferation. However, over-expression of RELMβ suppressed the in vitro adhesion, invasion and metastasis of cancer cells, accompanied by decreased expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. Moreover, transfection of RELMβ attenuated the expression of vascular endothelial growth factor and in vitro angiogenic capabilities of cancer cells. CONCLUSION: Over-expression of RELMβ abolishes the invasion, metastasis and angiogenesis of gastric cancer cells in vitro, suggesting its potentials as a novel therapeutic target for gastric cancer.

Optimization of process parameters for in situ casting of Al/TiB_2 composites through response surface methodology

The mathematical models were developed to predict the ultimate tensile strength （UTS） and hardness of Al/TiB2 MMCs fabricated by in situ reaction process. The process parameters include temperature, reaction time and mass fraction of TiB2. The in-situ casting was carried out based on three-factor five-level central composite rotatable design using response surface methodology （RSM）. The validation of the model was carried out using ANOVA. The mathematical models developed for the mechanical properties were predicted at 95% confidence limit.

Improvement of Copper-inducible Gene Expression System for Plant

The copper-regulated gene expression system has been developed to control spacial and temporal expression of transgene in plant. It comprises two parts: (1) ace I gene encoding copper-responsive transcription factor under the control of a constitutive or organ-specific promoter, and (2) a gene of interest under the control of a chimeric promoter consisting of the CaMV 35S (-90 to +8) promoter linked to the metal responsive element (MRE) carrying activating copper-metallothionein expression (ACE1)-binding sites. Here, the effectiveness of two different ACE1-binding cis -elements which derive from 5'-regulatory region of yeast metallothionein gene was investigated in transgenic tobacco (Nicotiana tabacum L. cv. W38). The results revealed that the MRE (-210 to -126) could increase the system inducibility by 50% - 100% compared with the previously reported MRE (-148 to -105). It is potential to use the copper-inducible system to control valuable gene traits in plant biotechnology.

Design and R＆D Progress of China Lead-Based Reactor for ADS Research Facility

In 2011,the Chinese Academy of Sciences launched an engineering project to develop an acceleratordriven subcritical system(ADS)for nuclear waste transmutation.The China Lead-based Reactor(CLEAR),proposed by the Institute of Nuclear Energy Safety Technology,was selected as the reference reactor for ADS development,as well as for the technology development of the Generation IV lead-cooled fast reactor.The conceptual design of CLEAR-I with 10 MW thermal power has been completed.KYLIN series lead-bismuth eutectic experimental loops have been constructed to investigate the technologies of the coolant,key components,structural materials,fuel assembly,operation,and control.In order to validate and test the key components and integrated operating technology of the lead-based reactor,the lead alloy-cooled non-nuclear reactor CLEAR-S,the lead-based zero-power nuclear reactor CLEAR-0,and the lead-based virtual reactor CLEAR-V are under realization.

Advanced Pt‐based intermetallic nanocrystals for the oxygen reduction reaction

Proton exchange membrane fuel cells(PEMFCs)are considered ideal energy‐conversion devices because of their environmentally friendly nature and high theoretical energy efficiency.However,cathodic polarization,which is a result of the sluggish oxygen reduction reaction(ORR)kinetics,is a significant source of energy loss and reduces fuel cell efficiency.Further,the need to use Pt in commercial Pt/C cathodes has restricted their large‐scale application in fuel cells because of its high cost and poor durability.Thus,improvements in the activity and durability of Pt‐based catalyst are required to reduce the amount of Pt required and,thus,costs,while increasing the ORR rate and fuel cell power density and promoting widespread PEMFC commercialization.In recent years,atomically ordered Pt‐based intermetallic nanocrystals have received tremendous attention owing to their excellent activity and stability for the ORR.Therefore,in this review,we first introduce the formation of intermetallic compounds from the perspective of thermodynamics and kinetics to lay a theoretical foundation for the design of these compounds.In addition,optimization strategies for Pt‐based ordered intermetallic catalysts are summarized in terms of the catalyst composition,size,and morphology.Finally,we conclude with a discussion of the current challenges and future prospects of Pt‐based ordered alloys.This review is designed to help readers gain insights into the recent developments in and rational design of Pt‐based intermetallic nanocrystals for the ORR and encourage research that will enable the commercialization of PEMFCs.

Microstructures and mechanical properties of in-situ TiB2/Al−xSi−0.3Mg composites

In-situ 2 vol.%TiB2 particle reinforced Al−xSi−0.3Mg(x=7,9,12,15 wt.%)composites were prepared by the salt−metal reaction,and the microstructures and mechanical properties were investigated.The results show that the TiB2 particles with a diameter of 20−80 nm and the eutectic Si with a length of 1−10μm are the main strengthening phases in the TiB2/Al−xSi−0.3Mg composites.The TiB2 particles promote grain refinement and modify the eutectic Si from needle-like to short-rod shape.However,the strengthening effect of TiB2 particles is weakened as the Si content exceeds the eutectic composition,which can be attributed to the formation of large and irregular primary Si.The axial tensile test results and fractography observations indicate that these composites show more brittle fracture characteristics than the corresponding alloy matrixes.

Oxidation behaviors of wrought nickel-based superalloys in various high temperature environments

Oxidation characteristics of Alloy 617 and Haynes 230 at 900 oC in simulated helium environment,hot steam environment containing H2 as well as in air and pure helium conditions were investigated.Compared to air condition,the oxidation rate of Alloy 617 was not significantly affected in helium and hot steam environments,while Haynes 230 showed lower oxidation rate in helium environment.On the other hand,the oxide morphology and structure of Alloy 617 were strongly affected by the environments,but those of Haynes 230 were less dependent on the environments.For Haynes 230,a Cr2O3 inner layer and a protective MnCr2O4 outer layer were formed in all environments,which contributed to the better oxidation resistance.As the mechanical properties,such as creep and tensile properties,were significantly affected by the oxidation behaviors,surface treatment methods to enhance oxidation resistance of these alloys should be developed.

美国国防技术发展——改进新技术转化的管理流程

推进技术革新对于美国国防部保持其绝对优势是至关重要的。而推进技术革新的关键是：如何将有前景的技术从实验室和商业环境迅速转换到实际应用中。目前，美国国防部正在尝试新的管理办法和标准，以解决技术转化过程中存在的问题。文中给出了三个新技术转型项目：TTI、DACP和快速反应基金，它们对新的管理流程进行了实践。评估结果表明，虽然新的管理流程仍存在着一定问题，并且也还不能确定其最终的影响和效果；但在已完成项目的实施过程中，应用新的管理流程的确加快了技术革新、节省了开支、使国防部从商业性公司得到更多的创新性技术以应用于军事领域。

Semi-heterogeneous photo-Cu-dual-catalytic cross-coupling reactions using polymeric carbon nitrides

A merger of copper catalysis and semiconductor photocatalysis using polymeric carbon nitride(PCN)for multi-type cross-coupling reactions was developed.This dual-catalytic system enables mild C-H arylation,chalcogenation,and C-N cross-coupling reactions under visible light irradiation with a broad substrate scope.Good-to-excellent yields were obtained with appreciable site selectivity and functional group tolerance.Metal-free and low-cost PCN photocatalyst can easily be recovered and reused several times.

Spiny Pd/PtFe core/shell nanotubes with rich high-index facets for efficient electrocatalysis

The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.

Reaction mechanism and chemoselectivity of gold(Ⅰ)-catalyzed cycloaddition of 1-(1-alkynyl) cyclopropyl ketones with nucleophiles to yield substituted furans

The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.

The ultraviolet photoconductive detector based on Al-doped ZnO thin film with fast response

We report fabrication and characterization of metal-semiconductor-metal photoconductive detectors based on Al-doped ZnO thin films fabricated by radio frequency magnetron sputtering.Optical and structural properties of the thin films were characterized using various techniques.At 6 V bias,a responsivity higher than 4 A/W in the wavelength shorter than 350 nm was obtained,and this responsibility dropped quickly and reached the noise floor in the visible region.Transient response measurement revealed that the detector had a fast photoresponse with a rise time of 9 ns and a fall time of 1.2 μs.

Cobalt single atoms anchored on N-doped ultrathin carbon nanosheets for selective transfer hydrogenation of nitroarenes

Selective transfer hydrogenation of nitroarenes to amines with transition metal nanocatalysts is appealing due to its low-cost, moderate reaction conditions, good activity and excellent selectivity. Single-atom catalysts (SACs) possessing advantages of maximum atom efficiency and particular electronic structure are expected to be more effective for this reaction, yet no report about it. Herein, cobalt single atoms anchored on N-doped ultrathin carbon nanosheets (denoted as CoSAs/NCNS) were produced and demonstrated as an outstanding SAC for selective transfer hydrogenation of nitroarenes to amines with formic acid as hydrogen donor. The turnover frequency (TOF) reached 110.6 h^-1, which was 20 times higher than the best results of cobalt nanopartides reported in literatures under similar reaction conditions. Moreover, CoSAs/NCNS exhibited excellent selectivity for a variety of nitroarenes bearing other reducible functionalities, such as iodo, cyano, keto, vinyl, alkynyl and ester groups. The findings further highlight the ability and advantages of SACs in heterogeneous catalysis.

Direct silylation reactions of inert C-H bonds via transition metal catalysis

In the past thirty years,transition metal catalyzed silylation of inert C–H bonds has attracted intensive attention due to the importance and wide use of organosilicon compounds.In this review,the silylation reactions of inert C–H bonds catalyzed by transition metal complexes of Ir,Rh,Ru,Pt,Pd,Ni,and Sc,and the strategies utilized to access the site-selective C–H silylation products have been summarized.Furthermore,the mechanisms of C–H silylation reactions have been discussed briefly.