3,616 research outputs found

    Not quite the 'Great Britain of the Far East': Japan's security, the US-Japan alliance and the 'war on terror' in East Asia

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    Japan, in responding to US expectations for support in the 'war on terror', has displayed a degree of strategic convergence on global security objectives, thus prompting policy-makers and observers to dub it the 'Great Britain of the Far East'. This article argues, however, that Japan is far from assuming this role. For Japan, the 'war on terror' serves more as a political pretext for legitimating long-planned changes in military security policy that are often only marginally related to the US's anti-terrorism agenda. Instead, Japan has focused much more on using the terror threat rationale as a means to push forward its response to the regional and traditional security challenges of North Korea and China, even if at times it attempts to depict both as 'new security challenges' or as involving elements of counterterrorism. The final conclusion is that US military hegemony may be weakened by Japan's and the Asia-Pacific's potential divergence from the US global security agenda

    Enantioselective synthesis and application to the allylic imidate rearrangement of amine-coordinated palladacycle catalysts of cobalt sandwich complexes

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    The reaction of (η5-(N,N-dimethylaminomethyl)cyclopentadien-yl)(η4-tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)-N-acetylphenylalanine gave planar chiral palladacycle di-μ-chloridebis[(η5-(Sp)-2-(N,N-dimethylaminomethyl)cyclopentadienyl,1-C,3′-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium [(Sp)-Me2-CAP-Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)-proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (Sp)-Me2-CAP-OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)-N-acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N-diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(Sp)-Pyrr-CAP-Cl] and AgNO3 (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)-N-aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)-trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non-racemic allylic amine derivatives

    Planar chiral palladacycle precatalysts for asymmetric synthesis

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    Chiral non-racemic palladacycles were employed as precatalysts for Pd(0) mediated asymmetric synthesis. Addition of HPAr2/base to a ferrocenyloxazoline planar chiral palladacycle resulted in ligand synthesis and palladium capture to give a bidentate Phosferrox/Pd(0) complex. A series of these complexes were generated in situ and applied successfully as catalysts for asymmetric allylic alkylation

    A Value Model Approach to Reduce PM Cargo’s Costs for the CH-47F Chinook Helicopter

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    The CH-47F is a multifaceted system incorporating a series of technological improvements that aim to improve flight crews’ performance. The new Chinook model marks a transition away from platforms with steam gauge based cockpits, federated mission systems equipment, and analog flight control augmentation systems. The aircraft has a highly integrated glass cockpit and digital flight control augmentation system reducing the crew’s workload and improving other capabilities, such as auto-hovering. This allows pilots to focus on aspects essential for mission success while operating in challenging environments. PM Cargo is responsible for maintaining the CH-47F to meet these demands, however, this has significant financial challenges to consider. PM Cargo asked us to produce courses of action that will reduce costs while also adding value to the CH-47F program. This will ensure the CH-47F, through PM Cargo’s stewardship, remains a staple of the United States Army into the future

    Enantiopure planar chiral and chiral-at-metal iridacycles derived from bulky cobalt sandwich complexes

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    Reaction of (η5-(S)-2-(4-methylethyl)oxazolinylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt with [IrCp*Cl2]2 in acetonitrile with KPF6 and KOt-Bu resulted in S,Sp,SIr and S,Rp,RIr configured acetonitrile and Cp* coordinated cationic iridacycles (d.r. up to 4.8 : 1 – kinetic control), the planar chiral configuration dictating the configuration of the pseudo-tetrahedral iridium-based stereogenic centre. Addition of water to the cycloiridation reaction resulted in an increase in yield (up to 78%) at the cost of diastereoselectivity. Use of the corresponding substrate containing a t-Bu rather than an i-Pr substituted oxazoline gave exclusively the S,Sp,SIr diastereoisomer, and under the same conditions (S)-2-ferrocenyl- 4-(1,1-dimethylethyl)oxazoline cycloiridated to give only the S,Sp,SIr diastereoisomer. Substitution reactions of the title complexes at iridium proceeded with retention of configuration, a computational study revealing the proposed coordinatively unsaturated intermediate of a dissociative mechanism to display a relatively weak Co-Ir interaction, and a pronounced steric effect as the basis of stereocontrol

    Fluorocarbene, Fluoroolefin, and Fluorocarbyne Complexes of Rh

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    The manuscript reports the synthesis, characterization, and analysis of electronic structure in a series of complexes of small perfluorocarbon ligands with the (PNP)Rh fragment (where PNP is a diarylamido/bis(phosphine) pincer ligand). Reactions of (PNP)Rh(TBE) as the source of (PNP)Rh with CHF3 and C2HF5 produced perfluoroalkylidene complexes (PNP)RhCF2 and (PNP)RhC(F)(CF3). (PNP)RhCF2 could also be obtained via the reaction of (PNP)Rh(TBE) with Me3SiCF3/CsF, with an admixture of (PNP) Rh(C2F4), where TBE = tert-butylethylene. Abstraction of fluoride from these neutral (PNP)RhCxFy complexes was successful, although only abstraction from (PNP)Rh]CF2 allowed unambiguous identification of the Rh product, [(PNP)Rh CF] +. DFT computational studies allowed comparison of relative energies of (PNP)Rh(C2F4) and [(PNP)Rh(C2F3)]+ isomers as well as comparisons between the electronic structure of the =CF2,C2F4, and CF+ complexes and their hydrocarbon analogues

    Rapid, Semi-Automated Fractionation of Freshwater Dissolved Organic Carbon Using DAX 8 (XAD 8) and XAD 4 Resins in Tandem

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    Natural dissolved organic carbon (DOC) consists of different bio-molecular classes of compounds that are currently very difficult and time-consuming to isolate as individual compounds. However, it is possible to separate natural DOC into hydrophobic and hydrophilic fractions. Such characterisation approaches are becoming increasingly important because, over the past 20 years natural DOC concentrations have been rising rapidly in many parts of the world, most likely influenced by climate change. Higher DOC concentrations in drinking water catchments present a serious problem for the water industry because DOC can form disinfection by-products DBPs during water treatment (e.g. chlorination). Hence, there is an urgent need to better characterise natural DOC before, during and after water treatment. However, current DOC fractionation procedures are extremely laborious requiring days and continual manual monitoring to separate sufficient quantities of DOC for subsequent analysis. This seriously limits sample throughput and the parameter space which can be studied. In this paper, we propose a much more rapid semi-automated method (12.5 hours/litre/sample) which utilises readily available equipment, i.e., HPLC pump or similar and sequential columns of Amberlite DAX 8 and XAD 4 resins. The method reduces the manual input from continual attention to minutes. This paper describes the development of the method and its application in the fractionation of natural DOC from reservoir and lake samples fed from upland peat-land catchments. Recoveries are found to be comparable to those using the manual technique, with the dominant component being hydrophobic acid accounting for 35% - 40% of the natural DOC with the second largest, being hydrophilic acid at 20% - 27%
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