News Recommendations from Social Media Opinion Leaders: Effects on Media Trust and Information Seeking

Polls show a strong decline in public trust of traditional news outlets; however, social media offers new avenues for receiving news content. This experiment used the Facebook API to manipulate whether a news story appeared to have been posted on Facebook by one of the respondent's real‐life Facebook friends. Results show that social media recommendations improve levels of media trust, and also make people want to follow more news from that particular media outlet in the future. Moreover, these effects are amplified when the real‐life friend sharing the story on social media is perceived as an opinion leader. Implications for democracy and the news business are discussed.     

Viscosity characteristics of aqueous solutions of block copolymers of propylene and ethylene oxides

Brookfield viscosity measurements were made on aqueous solutions of surface-active agents composed of block copolymers of propylene and ethylene oxides in which the molecular weights of the polymers varied from 1100 to over 15,000. The hydrophobia bases were polyoxypropylene glycols varying in molecular weight from 940 to 4000. To these were added varying amounts of ethylene oxide so that the polyoxyethylene hydrophil comprised from 15 to 80% of the surfactant total weight. This work has materially expanded previous viscosity studies of aqueous solutions of nonionic surfactants by using a unique type of hydrophobe, two ethylene oxide chains, and far higher molecular weights of hydrophobe and of hydrophil, up to 280 moles of ethylene oxide. The surface-active agents with hydrophobe base molecular weights from 940 to 1100, and in which the polyoxyethylene sections comprised from 15 to 80% of the total weight, did not form gels in aqueous solution. Some surfactants with a hydrophobe base molecular weight of 1750 to 2750, to which varying amounts of polyoxyethylene were added, formed gels in water at a surfactant concentration range of 40% to 80%. With a hydrophobe molecular weight of 3250, gels formed at from 30% to 90% surfactant concentration, while with one nonionic derived from a 4000 molecular weight hydrophobe, a gel formed at only 20% polyol concentration. Two viscosity maxima were found in some cases, as reported occasionally for other systems. An increase in temperature from 0C to 50C generally reduced the viscosity of systems based on hydrophobes of 1175 and lower molecular weights, and increased it in systems based on hydrophobes of 1750 and higher molecular weights. The behavior of these surfactants in forminggels is explained on the basis of hydrogen bonding, micellar aggregation and water entrapment. The moles of water per ethylene oxide group in the adduct varied with the hydrophobe base weight and with the polyoxyethylene hydrophil, and within systems showing maximum viscosities, ranged from 0.3 to 17.1, at 25C, which is much higher than observed in other nonionics.     

Computer simulation of the biomass production rate of cyclic fed batch continuous culture

The biomass productivity of cyclically operated variable volume fermenters has been investigated as a function of the initial volume and the feed flow rate. The results of computer simulations show that the productivity-dilution rate curves are similar to those for a constant volume chemostat, which represents a limiting case for the cyclic operation. Both cyclic fed batch and fed batch plus batch operation have been studied for Monod and substrate inhibition kinetics. The results obtained for variable volume operation can be used to estimate the loss in productivity when a chemostat inadvertently undergoes volume fluctuations.     

Modular high frame rate detector for synchrotron applications

The development of detectors often lags the development in X-ray sources. However, advanced detectors are critical for fully utilizing and exploiting the capabilities of the new bright sources. We report on the development of a modular high frame rate detector for synchrotron applications such as small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS). The detector consists of four modules, each providing an imaging area of 5×5 cm(2) and capable of frame rates of 200 frames per second (fps) with full resolution, and 650 fps with smaller region of interest (ROI). Details of the detector design and experiments at synchrotron beamlines are discussed in the paper.     

Chemicals from Methanol

For good reasons, there has been a spate of articles, much thinking, and a fair amount of industrial action on making chemicals and fuels from methanol, Only methane and methanol are made commercially in over 99% yields from synthesis gas.     

Polar nephelometer based on a rotational confocal imaging setup

Rapid measurement of the angular distribution of light scattered by particles, the scattering phase function, is achieved by using a new type of polar nephelometer, a device for measuring the angular scattered-light intensity distribution, with a high angular precision and across many orders of magnitude of intensity. The design offers high-speed measurements and avoids many of the problems often associated with traditional goniometers when they are used for measurements of light scattering from small particles or biological cells in suspension. Our system relies on confocal imaging of the test space with off-axis parabolas, using a rotating mirror to scan the angular field of view at the second focus of a pair of conjugated parabolic mirrors, with the test space located at the first focus. The angular resolution of the system is limited mainly by the data-acquisition sampling frequency. In this proof-of-principle demonstration the system performs multiple scans of a 55 deg field of view in a very short time (<1 s). To significantly increase the signal-to-noise ratio, we averaged the successively acquired scans during this time. Polystyrene spheres dispersed in water at low concentrations were used to test the system. The scattering patterns obtained were found to be in good agreement with Mie theory calculations.     

Analysis of acetic acid productivity in a continuous two‐stage bioreactor with cell recycling

The performance of a two‐stage system with cell recycling and fresh feed at each stage is studied numerically for continuous acetic acid production. In this system, both filtrate and bleed broth from the first stage are supplied to the second fermenter. At high substrate conversions, this configuration is found to provide higher acetic acid productivities than either a previous configuration where only the first‐stage bleed broth is fed to the second stage or a single recycle chemostat at the same bleed ratios. Copyright © 2005 Society of Chemical Industry     

Vibration and Damping in Three-Bar Tensegrity Structure

The most interesting examples of tensegrity structures are underconstrained and display an infinitesimal flex. In the direction of that flex the force-displacement relationship is highly nonlinear, resulting from geometric stiffening and influenced by the effect of prestress at equilibrium. A tensegrity structure would therefore display nonlinear vibrations when excited in the direction of the infinitesimal flex, the “frequency” decreasing with amplitude. Movement in the direction of the flex occurs with only infinitesimal change in member length, and therefore under conventional models of material damping in members the motion would not vanish as rapidly as it would for a conventional oscillator. We study one particular tensegrity geometry for which we present the force-displacement relationship in analytical form and then examine the nonlinear vibrations. We observe the role of damping and we discuss those implications for the design of tensegrity structures in space applications.