This study examined the hypothesis that mycobacterial antigens generate different metabolic responses in macrophages as compared to gram‐negative effectors and macrophage activators. To this end, we utilized platinum electrodes and a light addressable potentiometric sensor to observe dynamic electrochemical changes in metabolic flux, as well as extracellular acidification. While phorbol myristate acetate (PMA) is commonly used to study macrophage activation, the concentration used to create this physiological response varies. The response of RAW‐264.7 macrophages is concentration‐dependent, where the metabolic response to high concentrations of PMA decreases suggesting deactivation. The gram‐negative effector, lipopolysaccharide (LPS), was seen to promote oxygen production which was used to produce a delayed onset of oxidative burst. Pre‐incubation with interferon‐γ (IFN‐γ) allowed a synergistic effect between IFN‐γ and LPS, allowing immediate initiation of oxidative burst. These studies exhibited a stark contrast with lipoarabinomannan (LAM), an antigenic glycolipid component associated with the bacterial genus Mycobacterium. The presence of LAM effectively inhibits any metabolic response preventing consumption of glucose and oxygen for the promotion of oxidative burst and to ensure pathogenic proliferation. This study demonstrates for the first time the immediate inhibitory metabolic effects LAM has on macrophages, suggesting implications for future intervention studies with Mycobacterium tuberculosis. 相似文献
We present a systematic analysis of the integral operators of potential theory that arise when solving the Helmholtz or Maxwell equations in the exterior (or interior) of a sphere in the frequency domain. After obtaining expressions for the signatures of layer potentials in the spherical harmonic or vector spherical harmonic basis, we turn to a consideration of various integral equations that have been proposed in the literature for problems of acoustic and electromagnetic scattering. The selection of certain parameters in “combined field” and “Calderon-preconditioned” formulations is shown to have a significant impact on condition number, extending earlier work by Kress and others. 相似文献
Silver-containing layered networks of the form [Ag(L)] (L = 4-pyridinesulfonate or p-toluenesulfonate) were treated with primary amines in different ratios. The structures of the parent supramolecular networks are well-known; however, their interactions with primary amines lead to the formation of new layered materials for which single-crystal X-ray structures cannot be obtained. Solid-state (109)Ag, (15)N, and (13)C cross-polarization magic-angle spinning (CP/MAS) NMR experiments, in combination with powder X-ray diffraction experiments and ab initio calculations, are utilized to investigate the interactions between the primary amines and the parent materials, and to propose structural models for the new materials. (109)Ag chemical shift (CS) tensor parameters are extremely sensitive to changes in silver environments; hence, (1)H-(109)Ag CP/MAS NMR experiments are used to distinguish and characterize silver sites. The combination of (109)Ag and (15)N NMR experiments on starting materials and samples prepared with both (15)N-labeled and unlabeled amines permits the accurate measurements of indirect (1)J((109)Ag,(15)N) and (1)J((109)Ag,(14)N) spin-spin coupling constants, providing further information on structure and bonding in these systems. First principles calculations of silver CS tensors and (1)J((109)Ag,(14)N) coupling constants in model complexes aid in formulating the proposed structural models for the new materials, which are largely comprised of layers of silver-diamine cations. 相似文献
Surface phonon cavities that are homogenous in both mechanical and dielectric properties are reported. The cavities are formed by the placement of a defect of a single domain within periodic domain inversion of single crystal piezoelectric lithium niobate that exhibits surface phononic bandgap through the phonon‐polariton coupling. Surface cavity resonances are observed within the bandgap, which manifest in entrapment of phonon‐polariton within the defect. In addition to demonstrating that the observed resonances are non‐radiative and decoupled to bulk radiation, which is critical for high Q cavities, it is also shown the possibility to tune the surface cavity resonance spectra simply by varying the defect width. Such an ability to excite surface cavity resonance that is non‐radiative with simultaneous localization of the electric field together with the advantage of a cavity that is physically formed from a completely monolithic and uniform material offers unique opportunities for widespread applications for example in actuation, detection, and phonon lasing that can be fully integrated with other physical systems such as quantum acoustics, photonics, and microfluidics.
A discussion in economic terms of common rules in conformity assessment based on measurement is given. The present work extends
tools of sampling when using inspection by variable and attribute, such as the setting of acceptance quality limits (AQL)
and limiting quality limits (LQL), by including an economic decision theory approach, leading, amongst other things, to a
new ‘cost’ curve as a complement to the traditional operating characteristic curves of statistical significance testing. The
methodology is of general applicability but is illustrated in the present work in the simple case of homogeneously pre-packaged
goods priced linearly with the amount of content. The relation to the optimised uncertainty methodology is explained. Optimum
strategies for the supplier are illustrated in terms of minimising production and testing costs, while at the same time maintaining
satisfactory levels of customer satisfaction.
The side-on bound metal complex of diazene cis-[Fe(NH[double bond]NH)(dmpe)(2)] was synthesised by reaction of [Fe(dmpe)(2)Cl(2)] with hydrazine in the presence of potassium graphite and characterised by (15)N NMR spectroscopy and X-ray crystallography. 相似文献
The synthesis of nucleoside analogues incorporating 4-(5-pyrimidinyl)-1,2,3-triazole aglycons as expanded purine nucleobase mimics were accessed using the copper-catalyzed azide-alkyne Huisgen cycloaddition between a ribosyl azide and 5-alkynylpyrimidines. Depending on the nature of the alkyne employed, other nucleoside analogues that possess fluorescence or potential metal-binding properties were prepared. Computational studies were undertaken on the purine analogues and indicate that the heterocycles of the unfused nucleobase prefer a coplanar arrangement and the anti-glycosidic conformer is favoured in most instances. 相似文献
Two new diruthenium(II,III) tetramidate compounds, Ru(2)(NHOCC(CH(3))(2))(4)Cl (1) and Ru(2)(NHOCCH(2)CH(3))(4)Cl (2) have been prepared and structurally characterized by X-ray crystallography. The activity of promoting sulfide oxygenation using simple oxidants such as hydrogen peroxide (H(2)O(2)) and tert-butyl hydroperoxide (TBHP) was studied. A UV-kinetics study indicated that the initial rates of 1 and 2 are comparable to the previously studied diruthenium tetracarboxylates in promoting TBHP oxygenation of methyl phenyl sulfide (MPS). Using excess oxidant and CH(3)CN as the solvent, organic sulfides MPS and diphenyl sulfide (PPS) were oxidized using 1 mol% of the catalytic species. Compound 1 is more effective than 2 in converting sulfides to sulfoxide under the same conditions. Fast conversion was achieved when the reactions were carried out in the solvent-free conditions, and the major oxidation product was the sulfoxide. The electronic structure of the title compounds was studied with DFT calculations to gain an understanding of the activation of peroxy reagents. 相似文献
The hydrogen storage properties of Fe(2)(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) and an oxidized analog, Fe(2)(O(2))(dobdc), have been examined using several complementary techniques, including low-pressure gas adsorption, neutron powder diffraction, and inelastic neutron scattering. These two metal-organic frameworks, which possess one-dimensional hexagonal channels decorated with unsaturated iron coordination sites, exhibit high initial isosteric heats of adsorption of -9.7(1) and -10.0(1) kJ mol(-1), respectively. Neutron powder diffraction has allowed the identification of three D(2) binding sites within the two frameworks, with the closest contacts corresponding to Fe-D(2) separations of 2.47(3) and 2.53(5) ?, respectively. Inelastic neutron scattering spectra, obtained from p-H(2) (para-H(2)) and D(2)-p-H(2) mixtures adsorbed in Fe(2)(dobdc), reveal weak interactions between two neighboring adsorption sites, a finding that is in opposition to a previous report of possible 'pairing' between neighboring H(2) molecules. 相似文献