Synthesis and Diels-Alder Reactions of a New Kind of Chiral Dienophiles: Cyclic Vinyl-p-tolylsulfilimines

A new kind of chiral dienophiles, cyclic vinyl-p-tolylsulfilimines (2a and 2b), were obtained from the corresponding (Z)-sulfinylacrylonitriles with HBF(4) and methanol. The asymmetric Diels-Alder reaction of optically pure 2a with cyclopentadiene under mild thermal or catalyzed conditions afforded only the endo-4a adduct with complete endo and pi-facial selectivities. The ability of the sulfilimine moiety to enhance the dienophilic reactivity of the double bond is similar to that of the sulfinyl group.     

Thermo-mechanical dynamics of nanoimprinting anti-reflective structures onto small-core mid-IR chalcogenide fibers [Invited]

Thermal nanoimprinting is a fast and versatile method for transferring the anti-reflective properties of subwavelength nanostructures onto the surface of highly reflective substrates, such as chalcogenide glass optical fiber end faces. In this paper, the technique is explored experimentally on a range of different types of commercial and custom-drawn optical fibers to evaluate the influence of geometric design, core/cladding material, and thermo-mechanical properties. Up to32.4% increased transmission and 88.3% total transmission are demonstrated in the 2–4.3 μm band using a mid-infrared(IR) supercontinuum laser.     

双柱碳纤维微电极的研究及其在测定多巴胺中的应用

报道了双柱微电极的制作方法,提出了用双柱碳纤维微电极在抗坏血酸存在下选择性地测定多巴胺.探讨了电极反应机理.多巴胺的浓度在5.0×10^-4～5.0×10^-6mol/L范围内与收集电流成正比.抗坏血酸浓度<5.0×10^-4mol/L时对测定结果无影响.     

Polysiloxane-Modified Mesoporous Materials

We report the preparation of polysiloxane-modified mesoporous silica gels derived from the acid catalysed hydrolysis of tetraethoxysilane (TEOS) and oligomeric silanol terminated polydimethylsiloxane (PDMS) in the presence of the non-ionic surfactant, octaethylene glycol monohexadecyl ether. The gels were characterised using thermal gravimetric analysis (TGA), infra-red (IR) spectroscopy, X-ray diffraction (XRD) and ²⁹Si solid state cross-polarisation (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. TGA and IR spectroscopy showed the loss of surfactant after calcination and a decrease in the Si–OH band at 950 cm^–1 indicated further condensation had occurred. This was confirmed by the increase in Q⁴ at –110 ppm, in ²⁹Si MAS NMR spectroscopy, which also showed that calcination had led to the redistribution of PDMS forming a T species. XRD data showed ordering within the structure, with an initial d-spacing of 45 Å, decreasing to 35 Å after calcination.     

Evaluating systems thinking in housing

This paper describes and evaluates work carried out in the social housing context in the United Kingdom using a systems thinking approach called ‘lean systems’ (LS). The work, sponsored by the Office of the Deputy Prime Minister, was designed to test whether LS could improve the efficiency of delivery of housing management and maintenance services. A pilot programme was developed in which three housing organizations used the approach in different service areas. The results indicate that LS can yield efficiency gains and improvements in service performance, customer satisfaction and staff morale—although securing and sustaining these results requires considerable organizational commitment. The LS approach is outlined, work in the pilots described and the results presented. A theoretical analysis seeks to locate LS in the spectrum of systems methodologies and to delimit its particular area of competence.     

Phase diagrams of lyotropic cholesteric fluids

Experimental investigations of lyotropic cholesterics fluids are presented which show that changes in the shape anisotropy and chirality of the micellar population determine the topology of the temperature-concentration phase diagrams. For given amounts of the substances which induce the chirality and modify the shape anisotropy of the micelles, two distinct biaxial cholesteric phases are disclosed in the phase diagrams. This is interpreted in the framework of the catastrophe theory of phase transitions.     

A highly oriented cubic phase formed by lipids under shear

We demonstrate the formation of a macroscopically oriented inverse bicontinuous cubic (Q(II)) lipid phase from a sponge (L(3)) phase by controlled hydration during shear flow. The L(3) phase was the monoolein/butanediol/water system; the addition of water reduces the butanediol concentration, inducing the formation of a diamond (Q(II)(D)) cubic phase, which is oriented by the shear flow. The phenomenon was reproduced in both capillary and Couette geometries, indicating that this represents a robust general route for the production of highly aligned bulk Q(II) samples, with applications in nanomaterial templating and protein research.     

Induced Protic Behaviour in Aprotonic Ionic Liquids by Anion Basicity for Efficient Carbon Dioxide Capture

The interactions between aprotonic tetrabutylphosphonium carboxylate ionic liquids (ILs), [P_{4 4 4 4}][C_nCOO] (n=1, 2 and 7), and water were investigated. The cation-anion interactions occur via the α-¹H on [P_{4 4 4 4}]⁺ and the carboxylate headgroup of the anion. Upon addition, H₂O localises around the carboxylate headgroups, inducing an electron inductive effect towards the oxygens, leading to ion-pair separation. Studies with D₂O and [P_{4 4 4 4}][C_nCOO] revealed protic behaviour of the systems, with proton/deuterium exchange occurring at the α-¹H of the cation, promoted by the basicity of the anion, forming an intermediate ylide. The greater influence of van der Waals forces of the [P_{4 4 4 4}][C₇COO] system allows for re-orientation of the ions through larger interdigitation. The protic behaviour of the neat ILs allows for CO₂ to be chemically absorbed on the ylide intermediate, forming a phosphonium-carboxylate zwitterion, signifying proton exchange occurs even in the absence of H₂O. The absorption of CO₂ in equimolar IL-H₂O mixtures forms a hydrogen carbonate, through a proposed reaction of the CO₂ with an intermediate hydroxide, and carboxylic acid.