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In heterogeneous catalysis, the creation of gaseous products as bubbles in a liquid phase on the catalytic surface is associated with slip phenomena. In a microreactor, the slip length at the gas‐liquid interface is in the same order of magnitude as the reactor dimensions, which can affect fluid dynamics and transport phenomena. Here, the interplay of momentum, heat and mass transfer in a microreactor, when bubbles form on the catalytic surface, was investigated using two‐dimensional simulations. The effect of bubbles on the endothermic process of aqueous‐phase reforming of a glycerol solution was evaluated in terms of conversion and conversion and temperature in the reactor. Altogether, this study highlights the impact of bubbles, not only on the transport phenomena but also on the reactor performance. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising renewable energy source that can be produced from biomass using aqueous-phase reforming (APR). Here, using data obtained from AspenPlus and the literature, we evaluated the phase state, temperature-dependent enthalpy, and Gibbs free energy for the APR of small biomass model substrates. Phase equilibrium studies reveal that, under typical APR reaction conditions, the reaction mixture is in the liquid phase. Therefore, we show for the first time that the water-gas shift reaction (WGSR), which is the second main reaction of APR, must be modeled in the liquid phase, resulting in an endothermic instead of an exothermic enthalpy of reaction. A significant implication of this finding is that, although APR has been introduced as more energy saving than conventional reforming methods, the WGSR in APR has a comparable energy demand to the WGSR in steam reforming (SR). [ABSTRACT FROM AUTHOR]

Monolithic materials prepared from a mixture of n-lauryl methacrylate ( LMA) and ethylene glycol dimethacrylate ( EGDMA) dedicated to nano-liquid chromatography separation were synthesized using in situ UV polymerization in 75 µm inner diameter capillary tubing. A mixture of cyclohexanol and ethylene glycol was used as a porogen to control porosity. While the preparation conditions yielded satisfactory analytical results, values of pertinent parameters turned out to be critical for obtaining columns with efficient separation. In particular, the impact of two key parameters was studied here in an attempt to identify optimal preparation conditions: (a) different concentrations of the crosslinker EGDMA and (b) different porogen compositions while the monomer to porogen ratio was kept constant. Resulting monolithic phases were characterized in terms of permeability, mean pore diameter and swelling using three different eluents (water, acetonitrile and a mixture at maximum viscosity). First, the LMA/ EGDMA monolithic phases present peculiar morphology and hydrodynamic properties for 37% by weight of EGDMA, as reflected by the peak observed for their permeability and mean pore diameter. Swelling experiments revealed the coexistence of two phases in the monolithic structure: a highly crosslinked rigid phase which was insensitive to swelling in the presence of solvent and a weakly crosslinked flexible phase exhibiting significant swelling, with a transition to such a biphasic behavior taking place at 37% by weight of EGDMA. The effects of porogen composition and network swelling properties are presented based on a combination of the Flory − Huggins theory of isotropic mixing in polymer solutions and the Flory − Rehner theory of rubber elasticity in the affine network approximation. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Studying binding interactions involving living cells requires a platform that carefully mimics the physiological parameters that govern these phenomena. Very often the amount of ligands that receptors can bind affect overall binding strength as is the case in cell adhesion. In addition, the physical environment can strongly influence these processes. This is exemplified by the effect of shear stress in catch-bond-mediated binding of bacteria. Traditional analysis techniques do not allow to probe these factors simultaneously. To this end, continuous ligand gradients in locked-in supported lipid bilayers (SLBs) are prepared in a microfluidic device to control fluid flow. This platform allows for one-pot characterization of cell surface binding events and 1) the effect of ligand density and 2) shear stress, simultaneously. The model interaction between the FimH receptor found on Escherichia coli and mannose found on the mammalian cell membrane is used to evaluate the platform. Using a single chip, specific E. coli ORN 178 adhesion ( Kd of 0.9 × 10−21 m), detachment and displacement are shown to depend on the mannose-density and shear stress. For the first time, these effects are studied in a single chip device with high quality. This chip provides entry to further our understanding of other cell-cell interactions. [ABSTRACT FROM AUTHOR]

In this paper, we present a non-invasive assay using scanning electrochemical microscopy (SECM) for detecting osteogenic differentiation at physiological conditions (pH 7.5) on arrays of C2C12 microtissues. Upon exposure to bone morphogenic protein 2 (BMP-2), C2C12 microtissues differentiate and express alkaline phosphatase (ALP), which is indirectly detected through an enzymatic assay producing an electroactive species. The latter is detected using SECM by scanning at constant height over live microtissues at physiological pH (7.5) as well as more alkaline pH (8.5). As a control, expression of ALP is confirmed using a standard colorimetric assay. Detecting differentiation on live samples at physiological conditions represents a significant improvement for continuous monitoring of tissue differentiation or further use of the microtissues for, e.g., regenerative medicine. [ABSTRACT FROM AUTHOR]

A cover page for the journal is presented.