Multi sites vs single site for catalytic combustion of methane over Co3O4(110):A first-principles kinetic Monte Carlo study

Single-atom catalysts have been applied in many processes recently.The difference of their kinetic behavior compared to the traditional heterogeneous catalysts has not been extensively discussed yet.Herein a complete catalytic cycle of CH4 combustion assuming to be confined at isolated single sites of the Co3O4(110)surface is computationally compared with that on multi sites.The macroscopic kinetic behaviors of CH4 combustion on Co3O4(110)is systematically and quantitatively compared between those on the single site and multi sites utilizing kinetic Monte Carlo simulations upon the energetic information from the PBE+U calculation and statistic mechanics.The key factors governing the kinetics of CH4 combustion are disclosed for both the catalytic cycles respectively following the single-site and multi-site mechanisms.It is found that cooperation of multi active sites can promote the activity of complete CH4 combustions substantially in comparison to separated single-site catalyst whereas the confinement of active sites could regulate the selectivity of CH4 oxidation.The quantitative understanding of catalytic mechanism paves the way to improve the activity and selectivity for CH4 oxidation.

RADIATION-DAMPING EFFECTS IN THE BOUND-CONTINUUM TRANSITION OF HIGHLY-CHARGED ATOMIC-IONS

In a system consisting of an electron and a highly-charged ion,interaction with the radiation field is important.This means radiation-damping effects must be accurately taken into account.The present work discusses the radiation-damping effect in the processes of photoionization,radiative recombination,and electron scattering.

Lack of Effect of the 5-HT4 Receptor Ligands RS 67333 and RS 39604 on Murine Agonistic Behaviour

In comparison to studies investigating the roles of 5-HT1, 5-HT2 and 5-HT3 receptors in aggressive behaviour there is a dearth of material examining the function of 5-HT4 receptors in this behaviour. In view of this, the current study examined the effects of the 5-HT4 receptor partial agonist RS 67333 and antagonist RS 39604 in murine agonistic behaviour. RS 67333 failed to produce any significant changes in the offensive. Significant variation in the frequency of evade behaviour was detected but this occurred between treatment groups rather than with controls. Interestingly, both the frequency and duration of stretched attend behaviour were increased by RS 67333 0.1 mg/kg, a result indicative of increased risk assessment. The administration of RS 39604 (0.01 - 1 mg/kg) produced significant variation in the fre-quency and duration of following, and aggressive grooming. Frozen crouch behaviour was also increased significantly at 0.1 mg/kg. It is concluded that since the 5-HT4 receptor ligands employed in this study produced very few significant behavioural effects across the treatment groups, 5-HT4 receptors do not play a role in the modulation of murine aggressive behaviour.

Mapping High-Level Application Requirements onto Low-Level Cloud Resources

Cloud computing has created a paradigm shift that affects the way in which business applications are developed. Many business organizations use cloud infrastructures as platforms on which to deploy business applications. Increasing numbers of vendors are supplying the cloud marketplace with a wide range of cloud products. Different vendors offer cloud products in different formats. The cost structures for consuming cloud products can be complex. Finding a suitable set of cloud products that meets an application’s requirements and budget can be a challenging task. In this paper, an ontology-based resource mapping mechanism is proposed. Domain-specific ontologies are used to specify high-level application’s requirements. These are then translated into high-level infrastructure ontologies which then can be mapped onto low-level descriptions of cloud resources. Cost ontologies are proposed for cloud resources. An exemplar media transcoding and delivery service is studied in order to illustrate how high-level requirements can be modeled and mapped onto cloud resources within a budget constraint. The proposed ontologies provide an application-centric mechanism for specifying cloud requirements which can then be used for searching for suitable resources in a multi-provider cloud environment.

Global Standardization and Local Adaptation of Marketing--A Critical Review of the Literature

This paper discusses and critically reviews the causes and consequences of global standardization and local adaptation of marketing strategies.The scope of the literature review is in the fields of international marketing,international trade,and corporate strategic management.It also aims to emphasize finding gaps after reading the literature.Even though the studies’scope is extensive,this paper limits the reach:firstly,it introduces the standardization and local adaptation,discusses the advantages and disadvantages of both by researchers.At the same time,untangle the relationship between international marketing strategy and marketing mix.Secondly,it is divided into macro and micro to collate and analyze the leading factors affecting international strategy,so that the cross-market fit of global marketing tactic can be realised.Finally,focus on the KPI.The indicators of financial return were selected as the review from the factors representing the intuitive development level of the company.The goal was to concentrate on the mutual feedback and adjustment between the standardization/adaptation and performance of multinational companies.Among them,the diversities between developed and emerging markets are interspersed in each link.As this difference is a trend that scholars have begun to notice in recent years.Although many existed bibliographies are revolved around particular multinational companies or regions to assessment,this paper will focus on the impact of practical research article review and evaluation.It would not involve specific corporate and country.

Connections Between Induction Generator Effect and Open-loop Modal Proximity to Cause Sub-synchronous Oscillations in Series-compensated Power System

The induction generator effect(IGE)and the openloop modal proximity(OLMP)are two different reasons why subsynchronous oscillations(SSOs)in a series-compensated power system(SCPS)may occur.The IGE attributes the growing SSOs to negative resistance,while the OLMP explains the SSO mechanism from the standpoint of modal conditions.In this paper,we investigate the connections between the IGE and the OLMP through equivalent RLC circuit and open-loop modal analysis.Our investigation is conducted for two types of seriescompensated power systems where either a synchronous generator or a DFIG is connected at the sending end.The investigation reveals the conditions,in which the IGE and the OLMP may jointly cause the growing SSOs,i.e.,both the IGE and the OLMP can explain why the growing SSOs occur.Furthermore,the investigation indicates that the IGE and the OLMP may be totally irrelevant and lead to growing SSOs separately.This implies that it is possible that in a SCPS,the growing SSOs are only due to the IGE,and the OLMP is non-existent,and vice versa.Hence,when the growing SSOs occurs in a SCPS,examination based on both the IGE and the OLMP should be carefully conducted in order to find if the oscillatory instability is due to the IGE,or the OLMP,or both of them.

中国和美国原始土壤中非高温发现和鉴定

近年来在非极端环境中已经发现有古菌(Archaea)的存在, 但在中国原始土壤中还未见报道。本研究的目的是调查古菌是否存在于两个分别取自中国新疆和广西的土壤及两个美国亚利桑那州南部地区的土壤中。我们分别构建了这四个原始土壤的古菌16S rDNA文库并对28个克隆的16S rDNA进行了鉴定。所有这些16S rDNA的序列都归类于古菌的泉古菌门(Crenarchaeota)。进化树分析表明, 这些泉古菌的16S rDNA属于非高温陆地环境中的泉古菌种群, 明显区别于海洋和淡水地带的泉古菌种群。这个泉古菌种群又有两个分支, 这两个分支在16S rDNA序列上和G+C含量上有明显的区别。本研究在两个中国和两个美国原始土壤中鉴定了非高温泉古菌的存在, 由此证明泉古菌的存在范围不只局限于高温等极端环境。另外, 美国原始土壤中的泉古菌只属于一个进化分支, 这说明非高温泉古菌种群的类型和土壤的地理位置及土壤特性有关。

Rapid assessment of acid phosphatase activity in the mycorrhizosphere and in arbuscular mycorrhizal fungal hyphae

A pot experiment has been carried out under controlled conditions to study the possibility of applying the technique of in vivo staining for acid phosphatase activity on the roots of mycorrhizal plants and arbuscular mycorrhizal hyphae. The pots had 5 compartments. The central root compartment was separated from the two adjacent hyphal compartments using nylon nets of 30 μm mesh, and the two hyphal compartments were separated from the two outermost compartments with 0.45 μm membranes. Red clover was grown in the root compartment and was either inoculated with the arbuscular mycorrhizal fungus (AMF) Glomus mosseae or uninoculated. Sodium phytate was applied to all compartments. The results show that AMF can increase acid phosphatase activity of clover roots. The plant roots acquired deep red 'mycorrhizal prints'. The external hyphae also had obvious 'hyphal prints' on the test papers, indicating the ability of mycorrhizal hyphae to release acid phosphatase.

First principles study of Fenton reaction catalyzed by FeOCl:reaction mechanism and location of active site

Fe-based solid catalysts in promoting Fenton reaction to generate ·OH radical has drawn much attention,and interestingly,FeOCl was reported to have superior activity compared with the traditional Fe2 O3 catalysts.However,the mechanism of Fenton reaction on FeOCl and the origin of high activity remain unclear.Herein,by virtue of DFT+ U calculations,the H2 O2 decomposition and conversion mechanism on FeOCl(100)surface were systematically investigated.It is found that on clean FeOCl(100)surface,the exposed[Fe^3+-Fe^3+]sites can hardly break O-O bond of H2 O2 into OH groups,but instead H2 O2 tends to dehydrogenate by the surface lattice O,resulting in a series of side reactions and final conversion into O2,while the left H atoms gradually saturate the surface lattice O and reduce Fe^3+ into Fe^2+.On fully H-covered FeOCl(100),H2O2 can efficiently dissociate at[Fe^2+-Fe^2+]sites into two OH,but OH binds with Fe^2+ so strongly that it cannot desorb as OH radical as easily as that on Fe^3+.Interestingly,FeOCl(100)tends to be partially protonated in the real acid solution,which,along with H2 O2 dehydrogenation,results in the formation of active unit [Fe^2+-Fe^3+].On[Fe^2+-Fe^3+]unit,H2 O2 can easily break its O-O bond and OH at Fe3+ can desorb as OH radical,while the other OH at Fe^2+ couples with the surface H into H2O and finish the catalytic cycle.By comparison,Fe2 O3(012)cannot provide enough [Fe^2+-Fe^3+] active units due to the relative difficulty in H2 O2 dehydrogenation,which accounts for its inferior catalytic efficiency for Fenton reaction.

Identification of the active sites and mechanism for partial methane oxidation to methanol over copper-exchanged CHA zeolites

To make methane a suitable energy carrier and transport less costly,it is an urgent and challenging task for us to convert methane to liquid under mild conditions efficiently.In this study,we explored partial methane oxidation to methanol by density functional theory(DFT)calculations using a hybrid functional(HSE06)with van der Waals(vdW)interactions.The stabilities of different active sites over SSZ-13 and SAPO-34,two CHA type zeolites,are thoroughly investigated by ab initio molecular dynamics(AIMD)simulations and ab initio thermodynamics analyses.Four possible active sites,namely[CuOHCu]2+,[Cu(OH)2Cu]2+,[CuOCu]2+and[CuOH]+,are identified stable.Methane-to-methanol reaction mechanisms are further studied upon these most stable active sites,among which[CuOCu]2+and[CuOH]+are proved to be reactive.The migration of species among zeolite pores are also discussed,which accounts for the activity on[CuOH]+sites.This concept may represent a more complete picture of catalytic reactions over zeolites in general.