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41.
We describe protocols for the fabrication of microfluidic devices in plastics using a number of different embossing masters. Masters were fabricated by deep reactive ion etching (DRIE) of silicon (100), wet etching of silicon (100) and (110), and SU-8 processing. Structures embossed into a cyclo-olefin polymer were characterized in terms of the quality of pattern transfer as well as of the surface roughness. High quality pattern transfer was achieved with masters containing structures with angled sidewalls. Pattern distortions occurring during de-embossing were minimized by using masters consisting of SU-8 (which has a thermal expansion coefficient close to that of the substrates). Structures embossed with SU-8 masters also exhibited the lowest surface roughness. However, due to structural deformation, the reusability of the masters prepared for this study extended to only five embossing experiments. Masters fabricated on silicon, on the other hand, were more robust, but were subject to breakage during the de-embossing phase of the experiment. The results of this study will guide researchers in choosing master fabrication methods that will provide profile and surface characteristics of embossed microfluidic channels that are advantageous to their specific application. 相似文献
42.
43.
Mandy Eibisch Rosmarie Süß Jürgen Schiller 《Rapid communications in mass spectrometry : RCM》2012,26(13):1573-1576
44.
45.
Xiao Chen Elisabeth Kremmer Marie-Fran?oise Gouzy Ernst Clausen Mandy Starke Karin W?llner Gerd Pfister Anton Hartmann Petra M. Kr?mer 《Analytical and bioanalytical chemistry》2010,398(6):2655-2667
Quorum sensing (QS) is a communication mechanism between bacteria using diffusible chemical signaling molecules, which are
called autoinducers (AI). By detecting the concentration of quorum sensing molecules through binding to a specific receptor
protein, bacteria regulate their gene expressions when the concentration of autoinducers and thus the cell density reaches
a threshold level. Many Gram-negative bacteria use acylated homoserine lactones (HSLs) as autoinducers. Because of the broad
biological functions of HSLs, interest in detection and analysis of HSLs is increasing with a view to their medical, biotechnological,
and agricultural applications. In this study, an anti-HSL antibody-based immunochemical detection method has been developed.
Four structurally distinct HSL haptens, named HSL1, HSL2, HSL3, and HSL4, have been designed for antibody and assay development.
New rat anti-HSL monoclonal antibodies (mAbs) have been produced in-house and characterized with enzyme-linked immunosorbent
assays (ELISA), both in the coating antigen and in the enzyme tracer format. Eight mAbs (HSL1-1A5, HSL1-8E1, HSL1/2-2C10,
HSL1/2-4H5, HSL4-4C9, HSL4-5E12, HSL4-5H3, and HSL4-6D3) will be presented in this paper. We demonstrate that the anti-HSL
mAbs have distinguished sensitivity and selectivity toward HSLs depending upon their chemical structures. The optimized assays
are capable of detecting HSLs in the microgram per liter (low micromolar to nanomolar) range. The best IC50 (test midpoint) was 134 ± 30 μg L−1 (n = 54) for N-(3-oxodecanoyl)-l-homoserine lactone (3-oxo-C10-HSL) using mAb HSL1/2-2C10 and HSL1–HRP in the enzyme tracer format. In the coating antigen
format, the most selective mAb for N-octanoyl-l-homoserine lactone (C8-HSL) was mAb HSL4-4C9. Additionally, anti-HSL mAbs showed higher sensitivity against hydrolyzed HSLs,
namely homoserines. These compounds might also occur under certain biological conditions. This study marks the beginning of
new ways for quick and cost-effective HSL detection, requiring small sample amounts (less than 1 mL) and little to no sample
preparation. 相似文献
46.
Anna Celaya Anant P. Godbole Mandy Rae Schleifer 《Methodology and Computing in Applied Probability》2006,8(3):357-371
The classical Erdős–Ko–Rado (EKR) Theorem states that if we choose a family of subsets, each of size k, from a fixed set of size
, then the largest possible pairwise intersecting family has size
. We consider the probability that a randomly selected family of size t=t
n
has the EKR property (pairwise nonempty intersection) as n and k=k
n
tend to infinity, the latter at a specific rate. As t gets large, the EKR property is less likely to occur, while as t gets smaller, the EKR property is satisfied with high probability. We derive the threshold value for t using Janson’s inequality. Using the Stein–Chen method we show that the distribution of X
0, defined as the number of disjoint pairs of subsets in our family, can be approximated by a Poisson distribution. We extend
our results to yield similar conclusions for X
i
, the number of pairs of subsets that overlap in exactly i elements. Finally, we show that the joint distribution (X
0, X
1, ..., X
b
) can be approximated by a multidimensional Poisson vector with independent components.
相似文献
47.
[reaction: see text] N-Phenylsulfonylpyrrole 1 is magnesiated by treatment with isopropylmagnesium chloride and catalytic diisopropylamine. Reaction with various electrophiles, including palladium-catalyzed aryl- and heteroaryl cross-coupling, provides 2-substituted phenylsulfonylpyrroles in moderate to good yields. 相似文献
48.
Isotherms of capillary condensation are often used to determine the vapor sorption capacity of porous adsorbents as well as the pore size distribution by radii. In this paper, for calculating the volume of capillary condensate and of adsorption films in a porous body, an approach based on the theory of surface forces is used. Adsorption isotherms and disjoining pressure isotherms of wetting films are presented here in an exponential form discussed earlier. The calculations were made for straight cylindrical capillaries of different radii and slit pores of different width. The mechanisms of capillary condensation differ in cylindrical and slit pores. In cylindrical pores capillary condensation occurs due to capillary instability of curved wetting films on a capillary surface, when film thickness grows. In the case of slit pores, coalescence of wetting films formed on opposite slit surfaces proceeds under the action of attractive dispersion forces. Partial volumes of liquid in the state of both capillary condensate and adsorbed films are calculated dependent on the relative vapor pressure in a surrounding media. Copyright 2000 Academic Press. 相似文献
49.
Melnikov A Radu I Bovensiepen U Krupin O Starke K Matthias E Wolf M 《Physical review letters》2003,91(22):227403
Coherent spin dynamics in the THz domain coupled to a coherent phonon is observed in the time-resolved second harmonic response of the Gd(0001) ferromagnetic metal surface. An LO phonon of 2.9 THz is excited by a transient charge displacement at the surface caused by resonant absorption of a fs laser pulse in the exchange-split surface state. This lattice vibration modulates the interlayer distance inducing a coherent variation of the exchange interaction between spins in adjacent layers. The resulting magnetization dynamics is considered as optical magnon wave packets coupled to the phonon. 相似文献
50.