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831.
Dynamic single cell culture array 总被引:2,自引:0,他引:2
It is important to quantify the distribution of behavior amongst a population of individual cells to reach a more complete quantitative understanding of cellular processes. Improved high-throughput analysis of single cell behavior requires uniform conditions for individual cells with controllable cell-cell interactions, including diffusible and contact elements. Uniform cell arrays for static culture of adherent cells have previously been constructed using protein micropatterning techniques but lack the ability to control diffusible secretions. Here we present a microfluidic-based dynamic single cell culture array that allows both arrayed culture of individual adherent cells and dynamic control of fluid perfusion with uniform environments for individual cells. In our device no surface modification is required and cell loading is done in less than 30 seconds. The device consists of arrays of physical U-shaped hydrodynamic trapping structures with geometries that are biased to trap only single cells. HeLa cells were shown to adhere at a similar rate in the trapping array as on a control glass substrate. Additionally, rates of cell death and division were comparable to the control experiment. Approximately 100 individual isolated cells were observed growing and adhering in a field of view spanning approximately 1 mm(2) with greater than 85% of cells maintained within the primary trapping site after 24 hours. Also, greater than 90% of cells were adherent and only 5% had undergone apoptosis after 24 hours of perfusion culture within the trapping array. We anticipate uses in single cell analysis of drug toxicity with physiologically relevant perfused dosages as well as investigation of cell signaling pathways and systems biology. 相似文献
832.
Chiavarino B Crestoni ME Fornarini S Lemaire J Maître P MacAleese L 《Journal of the American Chemical Society》2006,128(38):12553-12561
[C(6)H(6)NO](+) ions, in two isomeric forms involved as key intermediates in the aromatic nitrosation reaction, have been produced in the gas phase and analyzed by IR multiple photon dissociation (IRMPD) spectroscopy in the 800-2200 cm(-)(1) fingerprint wavenumber range, exploiting the high fluence and wide tunability of a free electron laser (FEL) source. The IRMPD spectra were compared with the IR absorption spectra calculated for the optimized structures of potential isomers, thus allowing structural information on the absorbing species. [C(6)H(6)NO](+) ions were obtained by two routes, taking advantage of the FEL coupling to two different ion traps. In the first one, an FT-ICR mass spectrometer, a sequence of ion-molecule reactions was allowed to occur, ultimately leading to an NO(+) transfer process to benzene. The so-formed ions displayed IRMPD features characteristic of a [benzene,NO](+) pi-complex structure, including a prominent band at 1963 cm(-)(1), within the range for the N-O bond stretching vibration of NO (1876 cm(-)(1)) and NO(+) (2344 cm(-)(1)). A quite distinct species is formed by electrospray ionization (ESI) of a methanol solution of nitrosobenzene. The ions transferred and stored in a Paul ion trap showed the IRMPD features of substituent protonated nitrosobenzene, the most stable among conceivable [C(6)H(6)NO](+) isomers according to computations. It is noteworthy that IRMPD is successful in allowing a discrimination between isomeric [C(6)H(6)NO](+) species, whereas high-energy collision-induced dissociation fails in this task. The [benzene,NO](+) pi-complex is characterized by IRMPD spectroscopy as an exemplary noncovalent ionic adduct between two important biomolecular moieties. 相似文献
833.
Luke G. Rogers 《Journal of Functional Analysis》2006,235(2):619-665
We consider the problem of constructing extensions , where is the Sobolev space of functions with k derivatives in Lp and Ω⊂Rn is a domain. In the case of Lipschitz Ω, Calderón gave a family of extension operators depending on k, while Stein later produced a single (k-independent) operator. For the more general class of locally-uniform domains, which includes examples with highly non-rectifiable boundaries, a k-dependent family of operators was constructed by Jones. In this work we produce a k-independent operator for all spaces on a locally uniform domain Ω. 相似文献
834.
The idea of a finite collection of closed sets having “linearly regular intersection” at a point is crucial in variational
analysis. This central theoretical condition also has striking algorithmic consequences: in the case of two sets, one of which
satisfies a further regularity condition (convexity or smoothness, for example), we prove that von Neumann’s method of “alternating
projections” converges locally to a point in the intersection, at a linear rate associated with a modulus of regularity. As
a consequence, in the case of several arbitrary closed sets having linearly regular intersection at some point, the method
of “averaged projections” converges locally at a linear rate to a point in the intersection. Inexact versions of both algorithms
also converge linearly.
Research of A.S. Lewis supported in part by National Science Foundation Grant DMS-0504032.
Research of D.R. Luke supported in part by National Science Foundation Grant DMS-0712796. 相似文献
835.
Ron M. A. Heeren Donald F. Smith Jonathan Stauber Basak Kükrer-Kaletas Luke MacAleese 《Journal of the American Society for Mass Spectrometry》2009,20(6):1006-1014
Label-free imaging mass spectrometry provides a new look into different research areas. Will chemical mass microscopy on a biological system move from hype to hope?
836.
Changtong Hao Luke E. Adams Xinli Yang Martin Sadílek Frantiek Ture
ek 《International journal of mass spectrometry》2009,280(1-3):136
Experiments are reported that utilize surface neutralization of hyperthermal organic ions to obtain hyperthermal neutral species that are reionized on oxygen-activated rhenium surface and detected by mass spectrometry. A special Ping–Pong mass spectrometer was designed and coupled to a double-focusing mass spectrometer to allow energy and angle-resolved measurements. Neutralization of pyridine and benzene ions on gold, copper, and aluminum surfaces generated substantial ion currents into the collecting plate. The ion currents obtained on gold surfaces were found to depend on the recombination energy of the ion projectile. Hyperthermal neutrals coming off the first surface were found to mainly originate from hydrocarbon adsorbates. 相似文献
837.
Brigitte Städler Dr. Rona Chandrawati Andrew D. Price Dr. Siow‐Feng Chong Kerry Breheney Almar Postma Dr. Luke A. Connal Dr. Alexander N. Zelikin Dr. Frank Caruso Prof. 《Angewandte Chemie (International ed. in English)》2009,48(24):4359-4362
Fully loaded : Noncovalent anchoring of liposomes into polymer multilayered films with cholesterol‐modified polymers allows the preparation of capsosomes—liposome‐compartmentalized polymer capsules (see picture). A quantitative enzymatic reaction confirmed the presence of active cargo within the capsosomes and was used to determine the number of subcompartments within this novel biomedical carrier system.
838.
839.
840.
Rate constants for H atom attack on GeH4 and GeD4 have been measured in pulsed photolysis experiments in which H atoms were produced by the mercury-sensitized photolysis of H2 and monitored by Lyman-α absorption. The values obtained for GeD4 in the temperature range 293–550 K may be represented by the expression Combination of the rate constants for GeH4 measured in this work with those previously determined in this laboratory gives, for the temperature range 293–455 K, The kinetic isotope effect indicated by these expressions is given by which yields . This is the first determination of the kinetic isotope effect for radical attack on a Ge(SINGLE BOND)H bond. The present results for the reaction of H atoms with GeH4 have been combined with previously reported data, and the best value for the rate constant over the temperature range 210–473 K is recommended to be © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 237–243, 1997. 相似文献