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991.
Dongre C van Weerd J Besselink GA Vazquez RM Osellame R Cerullo G van Weeghel R van den Vlekkert HH Hoekstra HJ Pollnau M 《Lab on a chip》2011,11(4):679-683
We introduce a principle of parallel optical processing to an optofluidic lab-on-a-chip. During electrophoretic separation, the ultra-low limit of detection achieved with our set-up allows us to record fluorescence from covalently end-labeled DNA molecules. Different sets of exclusively color-labeled DNA fragments-otherwise rendered indistinguishable by spatio-temporal coincidence-are traced back to their origin by modulation-frequency-encoded multi-wavelength laser excitation, fluorescence detection with a single ultrasensitive, albeit color-blind photomultiplier, and Fourier analysis decoding. As a proof of principle, fragments obtained by multiplex ligation-dependent probe amplification from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, are simultaneously analyzed. 相似文献
992.
We present an all-numerical method for post-processing of the fluorescent signal as obtained from labeled molecules by capillary electrophoresis (CE) in an optofluidic chip, on the basis of data filtering in the Fourier domain. It is shown that the method outperforms the well-known lock-in amplification during experiments in the reduction of noise by a factor of (square root)2. The method is illustrated using experimental data obtained during CE separation of molecules from a commercial DNA ladder with 17 fluorescently labeled molecules having different base-pair sizes. An improvement in signal-to-noise ratio by a factor of ~10 is achieved, resulting in a record-low limit of detection of 210 fM. 相似文献
993.
In the present report, new protocols are introduced for automatic mesofluidic handling of irregularly shaped and non-uniformly sized bead materials for renewable micro-solid phase extraction (μSPE) under the lab-on-valve (LOV) format. To this end, two alternative strategies were studied comprising either (i) the direct aspiration of bead suspension placed at a container attached to LOV device or (ii) the aspiration of beads after a resuspension step, allowing the formation of a fluidized bed inside the beads’ container. Suspensions with homogeneously dispersed beads were also tested in the first strategy above, as prepared by increasing the viscosity of the suspension milieu with 75:15:10 glycerol/MeOH/H2O (in wt). The bead injection protocols were applied to four commercial reversed-phase sorbent materials with different sorptive surfaces: Oasis HLB, SupelMIP β-receptors, Lichrolut EN and Discovery DSC-MCAX, and the mass of sorbent packed in each microcolumn was assessed. Direct aspiration of methanolic suspensions gave rise to bead stacking and clogging of the LOV microconduits, resulting in a source of results with poor precision (RSD: 3.8-67.6%). The use of glycerolic suspensions was merely effective for repeatable sampling and packing of Oasis HLB and SupelMIP β-receptor beads without sorbent settlement along time. The resuspension strategy was able to handle all the materials tested with acceptable precision (RSD: 1.6-13.8%). Enhanced precision was attained (RSD <4.1%) when the sorbent bed was physically restricted to the volume of the LOV microchannel cavity. Different volumes of suspension aiming at a target mass of sorbent of 10 mg were successfully handled (RSD: 3.1-13.8%), showing the reliability of the bead resuspension approach for varied nominal bead sampling volumes. The proposed bead handling protocols were applied to μSPE of propranolol taken as a model of β-blocker from aqueous solutions by SupelMIP β-receptors and Discovery DSC-MCAX beads with high repeatability (RSD <6%) and absolute recoveries between 69 and 74% in a bead-injection mode. 相似文献
994.
In this note we give sufficient conditions on two dyadic systems on a space of homogeneous type in order to obtain the equivalence
of corresponding Haar systems on Lebesgue spaces. The main tool is the vector-valued Fefferman–Stein inequality for the Hardy–Littlewood
maximal operator. 相似文献
995.
In this note we investigate some basic properties of the level sets of functions which are homogeneous with respect to nonisotropic
dilations. In particular we obtain a formula for the volume of the level sets in terms of the area on the level surfaces.
We relate the results to some well known mean value formulas for solutions of PDE’s. 相似文献
996.
We analyze the behavior of the four-terminal resistance, relative to the two-terminal resistance of an interacting quantum wire with an impurity, taking into account the invasiveness of the voltage probes. We consider a one-dimensional Luttinger model of spinless fermions for the wire. We treat the coupling to the voltage probes perturbatively, within the framework of non-equilibrium Green function techniques. Our investigation unveils the combined effect of impurities, electron-electron interactions and invasiveness of the probes on the possible occurrence of negative resistance. 相似文献
997.
Hugo Martínez Snchez George Hadjipanayis Germn Antonio Prez Alczar Ligia Edith Zamora Alfonso Juan Sebastin Trujillo Hernndez 《Molecules (Basel, Switzerland)》2021,26(13)
In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd1.1Fe10CoTi compound from Nd2O3, Fe2O3, Co and TiO2. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn12-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N2. The magnetic properties Mr, µ0Hc, and (BH)max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were Mr = 75 Am2 kg–1, µ0Hc = 0.500 T and (BH)max = 58 kJ·m–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)max ~ 114 kJ·m–3 was obtained for 3 h and the highest µ0Hc = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape. 相似文献
998.
On compactness and cocompactness conditions for R-tors,R-pr and (big) lattices of classes of modules
Hugo Alberto Rincón-Mejía José Patricio Sánchez-Hernández Martha Lizbeth Shaid Sandoval-Miranda Manuel Zorrilla-Noriega 《代数通讯》2013,41(12):5240-5260
We study conditions related to compactness and cocompactness for some (big) lattices of classes of modules and preradicals. Also, we give some characterizations in terms of rings and modules. 相似文献
999.
Luis?Serrano-Ramón Amalio?Fernández-Pacheco Manuel Ricardo?Ibarra Dorothée?Petit Russell P.?Cowburn Tolek?Tyliszczak José?MaríaTeresa?De?TeresaEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(3):97
The propagation of domain walls in polycrystalline Co nanowires grown by focused-electron-beam-induced deposition is explored. We have found that Ga+ irradiation via focused ion beam is a suitable method to modify the propagation field of domain walls in magnetic conduits. Magneto-optical Kerr effect measurements show that global Ga+ irradiation of the nanowires increases the domain-wall propagation field. Additionally, we have observed by means of scanning transmission X-ray microscopy that it is possible to produce substantial domain-wall pinning via local Ga+ irradiation of a narrow region of the nanowire. In both cases, Ga+ doses of the order of 1016 ions/cm2 are required to produce such effects. These results pave the way for the controlled manipulation of domain walls in Co nanowires via Ga+ irradiation. 相似文献
1000.