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101.
A concise enantioselective synthesis of (S)-(-)-xylopinine (1) is described involving the addition of the laterally lithiated derivative of o-tolunitrile of 16 to enantiopure sulfinimine (+)-14. Treatment of the resulting cyano sulfinamide adduct (-)-17b with DIBAL-H accomplishes five operations in a single pot and furnishes the cyclic imine (+)-18 in good yield. Reduction and cyclization affords (S)-(-)-1. Alternatively basic hydrolysis of 17b,c gives isoquinolone 21 that is cyclized and reduced to give (S)-(-)-1. 相似文献
102.
Christodoulides N Mohanty S Miller CS Langub MC Floriano PN Dharshan P Ali MF Bernard B Romanovicz D Anslyn E Fox PC McDevitt JT 《Lab on a chip》2005,5(3):261-269
In the last decade, saliva has been advocated as a non-invasive alternative to blood as a diagnostic fluid. However, use of saliva has been hindered by the inadequate sensitivity of current methods to detect the lower salivary concentrations of many constituents compared to serum. Furthermore, developments in the areas related to lab-on-a-chip systems for saliva-based point of care diagnostics are complicated by the high viscosity and heterogeneous properties associated with this diagnostic fluid. The biomarker C-reactive protein (CRP) is an acute phase reactant and a well-accepted indicator of inflammation. Numerous clinical studies have established elevated serum CRP as a strong, independent risk factor for the development of cardiovascular disease (CVD). CVD has also been associated with oral infections (i.e. periodontal diseases) and there is evidence that systemic CRP may be a link between the two. Clinical measurements of CRP in serum are currently performed with "high sensitivity" CRP (hsCRP) enzyme-linked immunosorbent assay (ELISA) tests that lack the sensitivity for the detection of this important biomarker in saliva. Because measurement of salivary CRP may represent a novel approach for diagnosing and monitoring chronic inflammatory disease, including CVD and periodontal diseases, the objective of this study was to apply an ultra-sensitive microchip assay system for the measurement of CRP in human saliva. Here, we describe this novel lab-on-a-chip system in its first application for the measurement of CRP in saliva and demonstrate its advantages over the traditional ELISA method. The increased sensitivity of the microchip system (10 pg ml(-1) of CRP with 1000-fold dilution of saliva sample) is attributed to its inherent increased signal to noise ratio, resulting from the higher bead surface area available for antigen/antibody interactions and the high stringency washes associated with this approach. Finally, the microchip assay system was utilized in this study to provide direct experimental evidence that chronic periodontal disease may be associated with higher levels of salivary CRP. 相似文献
103.
Summary The rate of hydrolysis of the title cations obey the rate law:-d ln[Complex]/dt=kobs=k0+k1[OH–] in the range: 1pH3. The rate and activation parameters for acid and base hydrolysis (k0 and k1 paths respectively) are reported in the 40–60 °C range. 相似文献
104.
Ji‐Hye Jung Aruna Kumar Mohanty Jihwa Ye Taeheon Lee Junyoung Ahn Yeong‐Gweon Lim Taihyun Chang Hyun‐Jong Paik 《Journal of polymer science. Part A, Polymer chemistry》2017,55(24):4020-4026
Covalent fixed multicyclic polystyrene conformers were synthesized from inconvertible polystyrene conformers based on p‐tert‐butylthiacalix[4]arene by azidation and subsequent click coupling. Selective 1D NOESY analyses confirmed that the spatial structures of star polystyrene precursors and multicyclic polystyrenes were preserved during the azidation and click coupling processes. The conformation of star polymers affected degree of decrease in the hydrodynamic volume after cyclization but had little effect on glass transition behavior. The rigid core of star polymer increased the Tg but in the case of multicyclic polymer, this influence of core structure was reduced. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4020–4026 相似文献
105.
106.
Bulk viscous fluid distribution with massive strings in LRS Bianchi type-1 space time is studied. The exact solutions of the
field equations are obtained by using the equation of state ρ=−λ and ρ=λ. We observed that the bulk viscous fluid does not survive for ρ=−λ whereas it survives for ρ=λ. Some physical and geometrical properties of the models are discussed. 相似文献
107.
Silver selenide thin films were grown on silicon substrates by the solid-state reaction of sequentially deposited Se and Ag films of suitable thickness. Transmission electron microscopy and particle-induced X-ray emission studies of the as-deposited films showed the formation of single phase polycrystalline silver selenide from the reaction of Ag and Se films. Atomic force microscopy images of the as-deposited and films annealed at different temperatures in argon showed the film morphology to evolve into an agglomerated state with annealing temperature. The results indicate that when annealed above 473 K, silver selenide films on silicon become unstable and agglomerate through holes generated at grain boundaries. 相似文献
108.
Biswaranjan Mohanty V. K. Aswal J. Kohlbrecher H. B. Bohidar 《Journal of Polymer Science.Polymer Physics》2006,44(12):1653-1667
Length scale hierarchy in gelatin sol, gel, and coacervate (induced by ethanol) phases, having same concentration of gelatin in aqueous medium (13% w/v), has been investigated through small angle neutron scattering and rheology measurements. The static structure factor profile, I(q) versus wave vector q, was found to be remarkably similar for all these samples. This data could be split into three distinct q‐regimes: the low‐q regime, Iex(q) = Iex(0)/(1+q2ζ2)2 valid for q < 3Rg?1; the intermediate q‐regime, I(q) = I(0)/(1+q2ξ2) for 3Rg?1 < q < ξ?1; and the asymptotic regime, I(q) = (c/q) exp(?Rc2q2/2) for q > ξ?1. Consequently, three distinct length scales could be deduced from structure factor data: (a) inhomogeneity of size, ζ = 20 ± 1 nm for all the three phases; (b) average mesh size, ξ0 = 2.6 ± 0.2 nm for sol and gel, and smaller mesh size, ξos = 1.2 ± 0.2 nm for coacervate; and (c) cross section of gelatin chains, Rc = 0.35 ± 0.04 nm. In addition, the structure factor data obtained from coacervating solution analyzed in the Guinier region, I(q) = exp(?q2Rg2/3), yielded value of typical radius of gyration of clusters, Rg ≈ 69 nm that indicated existence of triple‐helices of length, L ≈ 239 nm; (d) Frequency and temperature sweep measurements conducted on coacervate samples revealed two other length scales: (e) viscoelastic length, ξve = 14 ± 2 nm and (f) correlation length at melting, ξT = 500 ± 70 nm. Thus, existence of six distinct length scales, (a–f), ranging from 1.2 to 500 nm has been established in the coacervate phase of gelatin–ethanol–water system. Results are discussed within the framework of Landau‐Ginzburg treatment of dynamically asymmetric systems (Prog Theor Phys 1977, 57, 826; Phys Rev A 1991, 44, R817; J Phys II (France) 1992, 2, 1631). © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1653–1667, 2006 相似文献
109.
In this paper, micromachined pipette arrays (MPAs) and microcombs were studied as a means of enabling high lane density gel electrophoresis. The MPA provide a miniaturized format to interface sub-microliter volumes of samples between macroscale sample preparation formats and microscale biochemical analysis systems. The microcombs provide a means of creating sample loading wells in the gel material on the same center-to-center spacing as the MPAs. Together, the two micromachined instruments provide an alternative to current combs and pipetting technologies used for creating sample loading wells and sample delivery in gel electrophoresis systems. Using three designs for the microcomb-MPA pair, center-to-center spacings of 1.0 mm, 500 microm, and 250 microm are studied. The results demonstrate an approximate 10-fold increase in lane density and a 10-fold reduction in sample size from 5 microL to 500 pL. As a result, the number of theoretical plates has increased 2.5-fold, while system resolution has increased 1.5-fold over the conventional agarose gel systems. An examination of changes in resolution across the width of individual separation lanes in both systems revealed dependence in the case of the conventional gels and no dependence for the gels loaded with the micromachined instrumentation. 相似文献
110.
This article is a review of the dissipation processes in nanoelectromechanical systems (NEMS). As NEMS technology becomes more and more prevalent in research and engineering applications, it is of great importance to understand the dissipative mechanisms that in part define the dynamic response of such devices. The purpose of this work is to understand, sort, and categorize dominant dissipation sources and to determine their significance with respect to physics processes and engineering considerations. 相似文献