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Lockery SR Hulme SE Roberts WM Robinson KJ Laromaine A Lindsay TH Whitesides GM Weeks JC 《Lab on a chip》2012,12(12):2211-2220
This paper describes the fabrication and use of a microfluidic device for performing whole-animal chemical screens using non-invasive electrophysiological readouts of neuromuscular function in the nematode worm, C. elegans. The device consists of an array of microchannels to which electrodes are attached to form recording modules capable of detecting the electrical activity of the pharynx, a heart-like neuromuscular organ involved in feeding. The array is coupled to a tree-like arrangement of distribution channels that automatically delivers one nematode to each recording module. The same channels are then used to perfuse the recording modules with test solutions while recording the electropharyngeogram (EPG) from each worm with sufficient sensitivity to detect each pharyngeal contraction. The device accurately reported the acute effects of known anthelmintics (anti-nematode drugs) and also correctly distinguished a specific drug-resistant mutant strain of C. elegans from wild type. The approach described here is readily adaptable to parasitic species for the identification of novel anthelmintics. It is also applicable in toxicology and drug discovery programs for human metabolic and degenerative diseases for which C. elegans is used as a model. 相似文献
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Janis Kliava Irina EdelmanOxana Ivanova Ruslan IvantsovEleonora Petrakovskaja Louis HennetDominique Thiaudière Marie-Louise Saboungi 《Journal of magnetism and magnetic materials》2011,323(5):451-460
We report electron magnetic resonance (EMR) and magnetooptical studies of borate glasses of molar composition 22.5K2O-22.5Al2O3-55B2O3 co-doped with low concentrations of Fe2O3 and MnO. In as-prepared samples the paramagnetic ions, as a rule, are in diluted state. However, in the case where the ratio of the iron and manganese oxides in the charge is 3/2, magnetic nanoparticles with characteristics close to those of manganese ferrite are formed already at the first stage of the glass preparation, as evidenced by both magnetic circular dichroism (MCD) and EMR. After thermal treatment all glasses show characteristic MCD and EMR spectra, attesting to the presence of magnetic nanoparticles, predominantly including iron ions. Preliminary EXAFS measurements at the Fe K-absorption edge show an emergence of nanoparticles with a structure close to MnFe2O4 after annealing the glasses at 560 °C.By computer simulating the EMR spectra at variable temperatures, a superparamagnetic nature of relatively broad size and shape distribution with the average diameter of ca. 3-4 nm. The characteristic temperature-dependent shift of the apparent resonance field is explained by a strong temperature dependence of the magnetic anisotropy in the nanoparticles.The formation of magnetic nanoparticles confers to the potassium-alumina-borate glasses magnetic and magneto-optical properties typical of magnetically ordered substances. At the same time, they remain transparent in a part of the visible and near infrared spectral range and display a high Faraday rotation value. 相似文献
36.
Classical molecular dynamics simulations have been performed for crystalline germanium with the aim to estimate the thermal effects within the first three coordination shells and their influence on the single-scattering and multiple-scattering contributions to the Ge K-edge extended x-ray absorption fine structure (EXAFS). 相似文献
37.
David J. Clarke Janis G. Matisons George R. Simon Marek Samoc Anna Samoc 《应用有机金属化学》2008,22(8):460-465
The first reported examples of polyhedral oligomeric silsesquioxane (POSS) cages containing a fulleropyrrolidine species are reported herein. Monosubstituted POSS‐dioxalane species were synthesized through the hydrosilylation of a silyl‐dioxalane with mono‐vinyl substituted POSS. Subsequent deprotection yielded the desired aldehyde functionality. An alternative synthetic pathway, involving the nucleophilic substitution of mono‐benzyl chloride POSS with 4‐hydroxybenzaldehyde yielded the desired aldehyde functionality. Each mono‐aldehyde POSS was then reacted with N‐methylglycine and C60 to yield the desired POSS fulleropyrrolidines. The prepared compounds were characterized by multinuclear NMR, electrospray mass spectrometry, elemental analysis, UV–vis, fluorescence and optical power limiting measurements. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
38.
Anatoly N. Trukhin Janis L. JansonsTatyana I. Dyuzheva Ludmila M. LityaginaNikolai A. Bendeliani 《Solid State Communications》2003,127(6):415-418
Luminescence of very small samples of single crystals of coesite and stishovite has been studied. The spectra were detected under ionizing radiation (X-ray and electron beam) and the decay kinetics of cathodoluminescence in the range of time from 10 ns to 3 ms was measured. The coesite luminescence possesses a broad band at 3 eV with exponential decay about 680 μs at 80 K. The nature of this luminescence was explained as a self-trapped exciton creation in tetrahedron framework. The stishovite luminescence possesses two bands—blue (2.8 eV) and UV (4.7 eV). The UV band intensity grows more than 20 times with irradiation dose from initial level. This shows that the corresponding luminescence centers could be induced by the radiation. The decay of the UV band possesses a fast and a slow component. The determination of the fast decay parameters is beyond the capabilities of our apparatus (less than 10 ns), whereas the slow decay of the UV is non-exponential and takes place in the range of hundreds of microsecond. The blue band decay kinetics can be well approximated by power law ∼t−2, which may correspond to recombination of defects created by radiation. The stishovite single crystal luminescence is very similar to that of germanium dioxide single crystal of rutile structure. The nature of the stishovite luminescence is explained as recombination of defects created by irradiation in octahedron-structured lattice. 相似文献
39.
Janis Castles Stevenson Stuart L. Cooper 《Journal of Polymer Science.Polymer Physics》1988,26(5):953-966
The multiple endothermic behavior of poly(tetramethylene terephthalate) (PTMT) and its random and block copolymers with poly(tetramethylene isophthalate) (PTMI) and poly(tetramethylene oxide) (PTMO) is described. The differential scanning calorimetry heating scans of these polymers exhibit up to four endotherms. Endotherm I, the lowest-temperature endotherm, is an annealing peak and is ascribed to a clustering of PTMT sequences. Endotherms II, III, and IV are associated with crystal populations originated during periods of isothermal crystallization, cooling, and heating, respectively. The dependence of the endotherms on sample composition, crystallization and annealing temperatures, crystallization and annealing times, and sample cooling and heating rate is discussed. 相似文献
40.
Michael I. Bruce Janis G. Matisons Brian K. Nicholson 《Journal of organometallic chemistry》1983,247(3):321-343
The syntheses of over sixty known and new derivatives of Ru3(CO)12 and H4Ru4(CO)12 by substitution reactions initiated by sodium diphenylketyl are described. The range of ligands studied includes isocyanides, tertiary phosphines and phosphites, tertiary arsines and SbPh3. The reactions are characterised by high degrees of specificity and conversion: under mild conditions up to four ligands can be introduced. Comparisons with the corresponding thermally induced reactions are made in several cases. The reactions provide routes to mixed ligand derivatives of the cluster carbonyls, although account of relative Lewis base strengths of the ligands may have to be taken. Possible mechanisms of these reactions are discussed briefly, as are the IR ν (CO) spectra of the Ru3 (CO)12-nLn complexes. 相似文献