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Channel Walls (channel + wall)
Selected AbstractsSol-gel-derived Poly(dimethylsiloxane) Enzymatic Reactor for Microfluidic Peptide MappingCHINESE JOURNAL OF CHEMISTRY, Issue 7 2006Hui-Ling Wu Abstract The silica-based poly(dimethylsiloxane) (PDMS) microfluidic enzymatic reactor was reported along with its analytical features in coupling with MALDI TOF and ESI MS. Microfluidic chip was fabricated using PDMS casting and O2 -plasma techniques, and used for the preparation of enzymatic reactor. Plasma oxidation for PDMS enabled the channel wall of microfluidics to present a layer of silanol (SiOH) groups. These SiOH groups as anchors onto the microchannel wall were linked covalently with the hydroxy groups of trypsin-encapsulated sol matrix. As a result, the leakage of sol-gel matrix from the microchannel was effectively prevented. On-line protein analysis was performed with the microfluidic enzymatic reactor by attachment of stainless steel tubing electrode and replaceable tip. The success of trypsin encapsulation was investigated by capillary electrophoresis (CE) detection, and MALDI TOF and ESI MS analysis. The lab-made device provided excellent extent of digestion even at the fast flow rate of 7.0 (L/min with very short residence time of ca. 2 s. In addition, the encapsulated trypsin exhibits increased stability even after continuous use. These features are the most requisite for high-throughput protein identification. [source] Fluorescent risedronate analogues reveal bisphosphonate uptake by bone marrow monocytes and localization around osteocytes in vivoJOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2010Anke J Roelofs Abstract Bisphosphonates are effective antiresorptive agents owing to their bone-targeting property and ability to inhibit osteoclasts. It remains unclear, however, whether any non-osteoclast cells are directly affected by these drugs in vivo. Two fluorescent risedronate analogues, carboxyfluorescein-labeled risedronate (FAM-RIS) and Alexa Fluor 647,labeled risedronate (AF647-RIS), were used to address this question. Twenty-four hours after injection into 3-month-old mice, fluorescent risedronate analogues were bound to bone surfaces. More detailed analysis revealed labeling of vascular channel walls within cortical bone. Furthermore, fluorescent risedronate analogues were present in osteocytic lacunae in close proximity to vascular channels and localized to the lacunae of newly embedded osteocytes close to the bone surface. Following injection into newborn rabbits, intracellular uptake of fluorescently labeled risedronate was detected in osteoclasts, and the active analogue FAM-RIS caused accumulation of unprenylated Rap1A in these cells. In addition, CD14high bone marrow monocytes showed relatively high levels of uptake of fluorescently labeled risedronate, which correlated with selective accumulation of unprenylated Rap1A in CD14+ cells, as well as osteoclasts, following treatment with risedronate in vivo. Similar results were obtained when either rabbit or human bone marrow cells were treated with fluorescent risedronate analogues in vitro. These findings suggest that the capacity of different cell types to endocytose bisphosphonate is a major determinant for the degree of cellular drug uptake in vitro as well as in vivo. In conclusion, this study shows that in addition to bone-resorbing osteoclasts, bisphosphonates may exert direct effects on bone marrow monocytes in vivo. © 2010 American Society for Bone and Mineral Research [source] Thermal and hydrodynamic characteristics of constructal tree-shaped minichannel heat sinkAICHE JOURNAL, Issue 8 2010Yongping Chen Abstract A three-dimensional thermal and hydrodynamic model for constructal tree-shaped minichannel heat sink is developed. The heat and fluid flow in the constructal heat sink with an inlet hydraulic diameter of 4 mm are numerically analyzed, taking into consideration conjugate heat transfer in the channel walls. The pressure drop, temperature uniformity, and coefficient of performance (COP) of the constructal tree-shaped heat sink are evaluated and compared with those of the corresponding traditional serpentine flow pattern. The results indicate that the constructal tree-shaped minichannel heat sinks have considerable advantages over the traditional serpentine flow patterns in both heat transfer and pressure drop. The strong and weak heat flow can be effectively allocated in tree-shaped flow structures; hence, the inherent advantage of uniform temperature on the heating surface in the constructal tree-shaped heat sink is demonstrated. And in tree-shaped flow structures, the local pressure loss due to confluence flow is found to be larger than that due to diffluence flow. In addition, an aluminum constructal tree-shaped minichannel heat sink is fabricated to conduct the verification experiment. The experimentally measured temperature distribution and pressure drop are in agreement with the numerical simulation, which verifies that the present model is reasonable. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Generalized slit flow of an ellis fluidPOLYMER ENGINEERING & SCIENCE, Issue 11 2001Ryszard T. Steller Isothermal, steady-state and fully developed flows of Ellis fluids in planar and annular slits are discussed. The flow equations derived for Ellis fluids describe also the flows of Newtonian and power law fluids as specific cases. The most important flows resulting from thp general theory, i.e., the pressure flows in flat and annular slits for stationary channel walls and at transverse and longitudinal movements of a wall, are analyzed in detail. Numerical verification of the results leads to the conclusion that the planar and annular flows of Ellis and power law fluids are qualitatively similar The quantitative differences resulting from the slit curvature and the type of constitutive equation are relatively large only for flows of strongly non-New-tonian liquids. [source] Nanostructuring polymers with cyclodextrins,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2-3 2005Cristian C. Rusa Abstract Bulk solid polymer samples formed by the coalescence of guest polymer chains from their inclusion compounds (ICs) formed with host cyclodextrins (CDs) can result in significant reorganization of their phase structures, morphologies, and even chain conformations from those more commonly produced from randomly-coiled, entangled polymer solutions and melts. When the cyclic host CDs are threaded by polymer chains to form crystalline polymer-CD-ICs, the guest polymers become highly extended due to the narrow host CD diameters (,5, 7, and 9 Ĺ for , -, , -, and , -CDs) and are segregated from neighboring guest polymer chains by the CD-IC channel walls. As a consequence, when polymer-CD-IC crystals are treated with CD solvents that do not dissolve the guest polymers or are treated with amylase enzymes, the resulting coalesced bulk polymer samples often display properties distinct from those of normally produced bulk samples of the same polymers. In this article the CD-IC processing of polymers to generate novel polymer microstructures and morphologies are described, to control the phase separation of immiscible blocks in block copolymers, and to form well-mixed intimate blends of two or more polymers that are normally incompatible. The thermal and temporal stabilities of polymer samples coalesced from their ICs formed with CDs will also be mentioned, and it is suggested that the range of polymer properties can be greatly expanded by their CD-IC processing. Copyright © 2005 John Wiley & Sons, Ltd. [source] Applications of field-flow fractionation in proteomics: Presence and futurePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2007Josef Chmelik RNDr.Article first published online: 19 JUL 200 Abstract Field-flow fractionation (FFF) represents a group of elution separation methods where external force fields act perpendicularly on analytes in a carrier liquid flows with nonuniform velocity profiles. It is an elution separation method that enables to separate analytes in relatively short times and collect fractions for further characterization or for investigation of their properties. Other advantages of FFF are small consumption of samples and gentle experimental conditions. These make FFF uniquely qualified for separation and purification of biological samples. The most promising are applications of different variants of flow FFF utilizing a cross flow through membrane channel walls to separate proteins. The separation is based on differences in protein diffusion coefficients, which allows calculating the size of macromolecules. Other FFF techniques (e.g., electrical, isoelectric, and sedimentation FFF) were also used for separation of biomolecules. FFF appears to be not only promising rapid technique for protein separation but it offers some other advantages in sample preparation, especially, focusing (hyperlayer) FFF techniques that enable preparation of homogeneous fractions of cells. Selected applications of FFF to protein analysis are described and future trends in application of FFF to proteomics are discussed. [source] Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite LCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2004André Devaux Dr. Abstract Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host,guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 ,s) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 ,s). A model of the host,guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations. [source] | |||||||||||||