Choice of parameters and stability of nonlinear vibration isolation device

Work of active vibration isolation devices with single-mass electromagnetic suspension taking into account of real characteristics of the voltage regulators is described. The analytical researches are carried out; the areas of stability of work of nonlinear vibration isolation device are defined

Acid Sensitive Ion Channels as Target of Hydrogen Sulfide in Rat Trigeminal Neurons

© 2016, Springer Science+Business Media New York.Hydrogen sulfide (H2S), an endogenous gasotransmitter, was proposed to act as a signaling molecule in a wide variety of pathophysiological processes including inflammation and nociception. Acid-sensing ion channels (ASICs) are voltage-insensitive, proton-gated cation channels activated by extracellular acidosis, and are involved in various pathologies of the nervous system including ischemia, stroke, and migraine. In this study, the effect of the H2S donor-sodium hydrogen sulfide (NaHS) on the firing of trigeminal (TG) nerve was explored using suction electrode recordings in peripheral branches of the TG nerve in isolated rat meninges, and patch clamp recordings of ASIC currents in isolated TG neurons. NaHS (100 μM) increased the action potential frequency of TG nerve and bath application of NaHS increased the amplitude of ASIC currents triggered by focal application of low pH solution on isolated TG neurons. We propose that activation of ASICs by H2S during chronic inflammation process contributes to the increased excitability of the TG system and may be implicated in the generation of nociceptive firing underlying migraine pain

Receptor properties of calix[4]resorcinarenes toward tetramethylammonium and choline cations in micellar solutions of sodium dodecyl sulfate

Concentration range of solubilization of calix[4]resorcinarene (H 8L) in sodium dodecyl sulfate (SDS) micelles was found. The interaction of the deprotonated form of H8L (tetraanions [H4L] 4-) with tetramethylammonium (TMA) and choline cations in micellar solutions of SDS was studied by pH-metry and NMR spectroscopy. The concentration dependences of the change in the cloud point in a multicomponent system TMA (choline)-[H4L]4-SDS-tetrabutylammonium bromide were determined. A correlation of these dependences with host-guest binding processes was found. The sharp change in the cloud points of the corresponding micellar solutions in concentration regions of TMA (0-5.10-4 mol L -1) and choline (0-1.1.10-3 mol L-1) is caused by the formation of inclusion complexes TMA (choline)-[H4L] 4- at the interface of the aqueous and micellar pseudophases. © 2006 Springer Science+Business Media, Inc

Receptor mechanisms mediating the pro-nociceptive action of hydrogen sulfide in rat trigeminal neurons and meningeal afferents

© 2017 Koroleva, Mustafina, Yakovlev, Hermann, Giniatullin and Sitdikova. Hydrogen sulfide (H 2 S), a well-established member of the gasotransmitter family, is involved in a variety of physiological functions, including pro-nociceptive action in the sensory system. Although several reports have shown that H 2 S activates sensory neurons, the molecular targets of H 2 S action in trigeminal (TG) nociception, implicated in migraine, remains controversial. In this study, using suction electrode recordings, we investigate the effect of the H 2 S donor, sodium hydrosulfide (NaHS), on nociceptive firing in rat meningeal TG nerve fibers. The effect of NaHS was also explored with p atch-clamp and calcium imaging techniques on isolated TG neurons. NaHS dramatically increased the nociceptive firing in TG nerve fibers. This effect was abolished by the TRPV1 inhibitor capsazepine but was partially prevented by the TRPA1 blocker HC 030031. In a fraction of isolated TG neurons, NaHS transiently increased amplitude of capsaicin-induced currents. Moreover, NaHS by itself induced inward currents in sensory neurons, which were abolished by the TRPV1 inhibitor capsazepine suggesting involvement of TRPV1 receptors. In contrast, the inhibitor of TRPA1 receptors HC 030031 did not prevent the NaHS-induced currents. Imaging of a large population of TG neurons revealed that NaHS induced calcium transients in 41% of tested neurons. Interestingly, this effect of NaHS in some neurons was inhibited by the TRPV1 antagonist capsazepine whereas in others it was sensitive to the TRPA1 blocker HC 030031. Our data suggest that both TRPV1 and TRPA1 receptors play a role in the pro-nociceptive action of NaHS in peripheral TG nerve endings in meninges and in somas of TG neurons. We propose that activation of TRPV1 and TRPA1 receptors by H 2 S during neuro-inflammation conditions contributes to the nociceptive firing in primary afferents underlying migraine pain

Influence of the structure of nonionic surfactants and the length of alkyl substituents of calix[4]resorcinarenes on their solubility, acid-base, and complexation properties

Regularities of solubilization of calix[4]resorcinarenes (H8L) with the variable length of hydrophobic radicals (R = CH3, C 3H7, C5H11, C7H 15, C8H17, C9H19, C 11H23) by the micelles of nonionic surfactants Triton X-100 and Triton X-405 in aqueous solutions were studied using solubility measurements. It was found that the solubilization capacity of surfactant micelles with respect to H8L and [H4]4- depends on the extension (thickness) of their polar layers. It was shown by means of potentiometric titration that, in solutions of nonionic surfactants, the constants of the interaction between tetraanions [H4L]4- and tetrametylammonium ions depend on the structure and concentration of nonionic surfactants and the hydrophobicity of H8L molecules. A change in the affinity of the [H4L]4- anions for protons and tetramethylammonium cations in nonionic surfactant solutions was revealed in relation to the length of substituents R and reagent concentrations

Effect of silica coating and further silica surface decoration by phospholipid bilayer on quenching of Tb(III) complexes by adrenochrome

© 2015 Elsevier B.V. Abstract The present report introduces regularities and mechanisms of Tb(III)-centered luminescence quenching by adrenochrome for Tb(III)-p-sulfonatothiacalix[4]arene complexes in the aqueous solutions and the same complexes doped into silica nanoparticles. The choice of adrenochrome (the oxidized form of adrenaline) as quencher originates from its quenching effect on the Tb(III)-centered luminescence, which discriminates it from adrenaline and dopamine. The quenching through dynamic mechanism of the Tb(III) complexes in the solutions results from their concentration induced collision with adrenochrome molecules. The quenching of the Tb(III)-doped silica nanoparticles also occurs through dynamic mechanism, although it is insignificant due to the shielding effect of the silica surface. The inclusion of the Tb(III)-doped silica nanoparticles into phospholipid bilayers influences the quenching of the Tb(III)-centered luminescence by adrenochrome due to its binding with the bilayers deposited onto silica nanoparticles

Extraction of lanthanum and gadolinium(III) at the cloud point using p-sulfonatocalyx[n]arenes as chelating agents

The extraction of gadolinium(III) and lanthanum(III) ions at the cloud point is studied in Triton X100 micellar solutions in a wide range of pH. In the absence of chelating agents, lanthanum(III) and gadolinium(III) ions are unselectively extracted at pH > 6. It is shown that the use of p-sulfonatothiacalyx[6(8)]arenes as chelating agents noticeably enhances the degree of extraction at pH 2-6. The composition and stability of lanthanum-p-sulfonatothiacalyx[n]arene complexes (n = 4, 6, 8) are estimated in a wide range of pH by pH-potentiometry. The degree of Gd3+ and La3+ ions extraction, which is performed at the cloud points employing calyxarene macrocycles of different sizes, is depended on the acidity of a medium. © 2009 Pleiades Publishing, Ltd

Impact of polyelectrolyte coating in fluorescent response of Eu(III)-containing nanoparticles on small chelating anions including nucleotides

© 2014 Elsevier B.V. The present work introduces a novel route to sense the permeability of the polyelectrolyte layer deposited onto luminescent core. The use of ternary Eu(III) complexes as the luminescent core enables to detect the permeability of the polyelectrolyte layers through the change of the Eu(III)-centered luminescence. The chelating anions, such as adenosine phosphates, glutamic acid and ethylenediaminetetraacetic acid disodium salt were used as substrates. The origin of the fluorescent response is the complex formation of the substrates with the Eu(III) complexes, which is greatly affected by the equilibrium concentration of the substrates at the surface of the core. The latter in turn is influenced by the permeability of the polyelectrolyte layer. The obtained results highlight the impact of the nature of the exterior layer in the penetration of the substrates through the negatively and positively charged polyelectrolyte layers

Fighting malaria without DDT : better management of the environment a key to disease control

French version available in IDRC Digital Library: Lutter contre le paludisme sans DDT : le contrôle de la maladie passe par une meilleure gestion de l'environnementSpanish version available in IDRC Digital Library: Combatiendo a la malaria sin DDT : mejor manejo ambiental, clave para el control de la enfermedadUnder the terms of the North American Free Trade Agreement, Mexico was committed to eliminating DDT use by 2002. The country’s malaria-control efforts, however, depended on this chemical. Researchers set about to develop alternate strategies by addressing factors that affect malaria’s spread: humans, mosquitoes, and the local environment in which the parasites persist. As a result of this integrated approach, Mexico was able to abandon DDT ahead of schedule

Solubilization and acidic and receptor properties of calix[4]resorcinarenes in aqueous solutions of oxyethylated dodecanol Brij-35

Solubilization of calix [4]resorcinarenes (Cn) with a varied length of hydrophobic substituents (R =Me, Pr, C5H11, C 7H15, C9H19, and C 11H23) in aqueous solutions of oxyethylated dodecanol Brij-35 was studied by the solubility method and 1D and 2D 1H NMR spectroscopy. The solubilization of Cn in micellar solutions of Brij-35 is caused by the formation of mixed Cn-Brij-35 aggregates and is weakened substantially with the elongation of R. It was shown by pH-metry and 1D 1H NMR spectroscopy that the receptor properties of the Cn anions toward the tetramethylammonium cations in the mixed aggregates differ substantially from those for the monomeric molecules in aqueous-organic and aqueous solutions. In particular, the binding of the tetramethylammonium cations does not result in screening of their N-Me fragments with the cyclophane cavity of the receptor. © 2005 Springer Science+Business Media, Inc