Efficient mixing of viscoelastic fluids in a microchannel at low Reynolds number

In this paper, we examined mixing of various two-fluid flows in a silicon/glass microchannel based on the competition of dominant forces in a flow field, namely viscous/elastic, viscous/viscous and viscous/inertial. Experiments were performed over a range of Deborah and Reynolds numbers (0.36 < De < 278, 0.005 < Re < 24.2). Fluorescent dye and microshperes were used to characterize the flow kinematics. Employing abrupt convergent/divergent channel geometry, we achieved efficient mixing of two-dissimilar viscoelastic fluids at very low Reynolds number. Enhanced mixing was achieved through elastically induced flow instability at negligible diffusion and inertial effects (i.e. enormous Peclet and Elasticity numbers). This viscoelastic mixing was achieved over a short effective mixing length and relatively fast flow velocities.     

Metal oxides as combustion catalysts for a stratified,dual bed partial oxidation catalyst

Bimetallic, dual bed catalysts made up of metal oxides were investigated in the millisecond catalytic partial oxidation of methane to synthesis gas. A metal oxide combustion catalyst containing manganese, chromium, or copper was coupled with a nickel reforming catalyst to carry out the partial oxidation of methane. These catalysts produce hydrogen yields that compare to a platinum/nickel dual bed catalyst at a fraction of the cost. The high space velocity of the millisecond reactor improves performance by giving high rates of heat convection from the exothermic, upstream combustion catalyst to the downstream, endothermic reforming catalyst. Additionally, over a 10 h experiment, the catalyst activity did not decrease.     

PAI-1 secretion and matrix deposition in human peritoneal mesothelial cell cultures: transcriptional regulation by TGF-beta 1

The thermally sensitive block copolymer, poly(N-isopropylacrylamide-b-dl-lactide) (PIPAAm-PLA), was synthesized by ring-opening polymerization of dl-lactide initiated from hydroxy-terminated poly (N-isopropylacrylamide) (PIPAAm). A PIPAAm bearing a single terminal hydroxyl group was prepared by telomerization using 2-hydroxyethanethiol as a chain-transfer agent. Successful preparation of PIPAAm and the PIPAAm-PLA block copolymer was verified by gel permeation chromatography (GPC) and 1H-NMR spectroscopy. Polymeric micelles were prepared from block copolymers using a dialysis method. Their solutions showed reversible changes in optical properties: transparent below a lower critical solution temperature (LCST) and opaque above the LCST. Dynamic light scattering measurements were used to observe the formation of micellar structures approximately 40 nm in diameter, which do not change between 20 degreesC and 30 degreesC. Above the LCST, polymer micelles aggregated, a phenomenon found to be reversible since the aggregates dissociated again by cooling below the LCST. Further observations using atomic force microscopy (AFM) confirmed this behaviour. The properties of this block copolymer system are interesting from both applied and fundamental perspectives, particularly for active targeting as drug carriers.     

Kinetic parameters for the vesicular acetylcholine transporter: two protons are exchanged for one acetylcholine

The vesicular acetylcholine transporter (VAChT) mediates ACh storage in synaptic vesicles by exchanging cytoplasmic ACh with vesicular protons. This study sought to determine the stoichiometry of exchange by analysis of ligand binding and transport kinetics. The effects of different pH values inside and outside, external ACh concentrations, and electrical potential gradients on ACh transport by vesicles isolated from the electric organ of Torpedo were determined using a pH-jump protocol. The equilibrium binding of a high-affinity analogue of ACh is inhibited by protonation with a pKa of 7.4 +/- 0.3. A two-proton model fits the transport data much better than a one-proton model does, and uptake increases at more positive internal electrical potential, as expected for the two-proton model. Thus, the results support the two-proton model. The transport cycle begins with binding of external ACh to outwardly oriented site 2 (KACho = 20 mM) and protonation of inwardly oriented site 1 (pKa1 = 4.73 +/- 0.05). Loaded VAChT reorients quickly (73 000 min-1) and releases ACh to the inside (KAChi = 44 000 mM) and the proton to the outside. Unloaded, internally oriented site 2 binds a proton (pKa2 = 7.0), after which VAChT reorients (150 +/- 20 min-1) in the rate-limiting step and releases the proton to the outside to complete the cycle. Rate constants for the reverse direction also were estimated. Two protons provide a thermodynamic driving force beyond that utilized in vivo, which suggests that vesicular filling is regulated. Other phenomena related to VAChT, namely the time required to fill synaptic vesicles, the fractional orientation of the ACh binding site toward cytoplasm, orientational lifetimes, and the rate of nonquantal release of ACh from cholinergic nerve terminals, were computer-simulated, and the results are compared with physiological observations.     

Dispersion characteristics of the broadside-coupled coplanarwaveguide

The dispersive properties for the even- and odd-modes of the broadside-coupled coplanar waveguide (CPW) are determined using the spectral domain method. Various numerical results of the even- and odd-mode effective dielectric constants as a function of frequency are presented and discussed. It is found that the structure has a very weak dispersion. This fact is further confirmed through a comparison between the calculated dynamic and quasi-static results of the even- and odd-mode effective dielectric constants. The low dispersion feature signifies the fact that the quasi-static analysis is adequate for designing practical microwave and millimeter-wave circuits employing broadside-coupled CPW     

Anticipating clinical integration of genetically tailored tobacco dependence treatment: perspectives of primary care physicians.

Emerging research will likely make it possible to tailor pharmacological treatment for individuals with tobacco dependence by genotype. This study explored primary care physicians' attitudes about the strengths of and barriers to using genetic testing to match patients to optimal nicotine replacement therapy. Four focus groups (n=27) were conducted, and data were analyzed using thematic content analysis. Physicians reported how likely they would be to offer patients a genetic test to tailor smoking treatment in response to three different scenarios that described characteristics of the genetic test based on published research. Respondents were on average 36 years of age; 59% were male and 67% were white. Physicians believed genetically tailored treatment may offer new hope to smokers trying to quit, yet they also noted several potential barriers to clinical integration. Barriers included erroneous assumptions by patients regarding the meaning of genetic test results, possible misinterpretation of information regarding racial differences in the prevalence of certain risk alleles, and potential discrimination against patients undergoing testing. Concerns increased dramatically when physicians were told that the same genotypes that would be identified to tailor smoking treatment also have been associated with increased risk of becoming addicted to nicotine, as well as other addictions and psychiatric disorders. Physicians were interested in the possibility of realizing improved smoking cessation outcomes through pharmacogenetic developments, but they also raised many concerns. Primary care physicians will need additional educational inputs and system support prior to integrating genetic testing for a common trait into their routine clinical practice.     

Too Proud to Let Go: Narcissistic Entitlement as a Barrier to Forgiveness.

Narcissistic entitlement impedes forgiveness in ways not captured by other robust predictors (e.g., offense severity, apology, relationship closeness, religiosity, Big Five personality factors), as demonstrated in 6 studies. Narcissistic entitlement involves expectations of special treatment and preoccupation with defending one's rights. In Study 1, entitlement predicted less forgiveness and greater insistence on repayment for a past offense. Complementary results emerged from Study 2, which used hypothetical transgressions, and Study 3, which assessed broad forgiveness dispositions. Study 4 examined associations with the Big Five, and Study 5 extended the findings to a laboratory context. Study 6 demonstrated that entitlement predicted diminished increases in forgiveness over time. Taken together, these results suggest that narcissistic entitlement is a robust, distinct predictor of unforgiveness. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A displacement measurement technique using millimeter-wave interferometry

A displacement measurement sensor, capable of sub-millimeter resolution, using millimeter-wave interferometry has been developed. The sensor operates at 37.6 GHz and is realized using both microwave integrated circuits and monolithic microwave integrated circuits. It has been used to accurately measure the displacement of metal plate location and water level. A resolution of only 0.05 mm is achieved. A maximum error of 0.3 mm is also attained without correction for the nonlinearity of the phase-detection processor and agrees well with the theoretical calculation.     

Adaptive calibration of a capacitance tomography system for imaging water droplet distribution

A highly sensitive electrical capacitance tomography (ECT) system based on an HP4284 impedance analyser has been developed and used to quantify low concentration multi-phase flows in wet gas separation processes. The system hardware provides high accuracy (0.05%) and high resolution (10⁻¹⁷ F). The sensor was calibrated in an environmental chamber with solid samples of known permittivity over ranges of temperature and humidity. Adaptive calibration and adjacent electrode pair correction techniques were applied to image very low concentration profiles. This paper describes the techniques used and presents the experimental results obtained from a test flow rig called Twister, which has been designed to separate liquid droplets from wet gas streams. The test results over a range of operating conditions (20–95% humidity) demonstrate that the ECT system is capable of reconstructing clear images of the droplet distribution inside Twister. Changes as small as 1 gWater/kgAir in the form of liquid droplets were detectable. It has also been shown that the concentration of the condensable phase can be estimated quantitatively within 20% in comparison with the reference measurements.