Indoor heterogeneous photochemistry of furfural drives emissions of nitrous acid

People spend approximately 80% of their time indoor, making the understanding of the indoor chemistry an important task for safety. The high surface-area-to-volume ratio characteristic of indoor environments leads the semi-volatile organic compounds (sVOCs) to deposit on the surfaces. Using a long path absorption photometer (LOPAP), this work investigates the formation of nitrous acid (HONO) through the photochemistry of adsorbed nitrate anions and its enhancement by the presence of furfural. Using a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS), this work also investigates the surface emissions of VOCs from irradiated films of furfural and a mix of furfural and nitrate anions. Among the emitted VOCs, 2(5H)-furanone/2-Butenedial was observed at high concentrations, leading to maleic anhydride formation after UV irradiation. Moreover, the addition of potassium nitrate to the film formed NO_x and HONO concentrations up to 10 ppb, which scales to ca. 4 ppb for realistic indoor conditions. This work helps to understand the high levels of HONO and NO_x measured indoors.     

Picosecond photodiffraction in semiconductor multiquantum wells and microcavities

We study the transient gratings photogenerated in the picosecond regime in three families of structures, namely : - structures of thickness in the order of one micron, including quantum wells (GaAs/GaAlAs, CdTe/ CdZnTe). A transmission modulation due to the electric field has been observed. We show that, in accordance with our calculations, this modulation is screened faster than 10 ps at a fluence of a few µJ/cm2. - A structure including GalnAs/GalnAsP MQWS in a cavity. This structure shows a top diffraction efficiency of 2.5 × 10-² at 1.55 µm for an energy of excitation in the order of 100 µJ/cm2. The diffraction efficiency exhibits several oscillations due to Fabry-Pårot effects. By introducing cavity effects in our model, we show that the diffraction efficiency is amplified by more than a factor 2 with respect to the no-cavity case. Calculations show that the diffraction efficiency may reach 6 × 10-² around 1.625 µm, for a front mirror reflectivity of 90 %. - Structures including bulk GaAs microcavities. The risetime is lower or in the order of 1 ps while the diffraction efficiency attains 1 %, with an average power of 4 mW (i.e. an energy of 2 µJ/cm²/pulse), compatible with a commutation of packets at 80 MHz.     

Scopolamine impairs human recognition memory: Data and modeling.

Eight subjects studied a set of complex visual images after administration of 0.4 mg scopolamine. Another 8 subjects performed the same task without drug administration. On a subsequent item recognition test, subjects rated, on a 5-point scale, their confidence that the studied pictures and an equal number of unstudied lures were actually presented. Results showed that scopolamine affected responses to studied items, but not unstudied lures, demonstrating an unambiguous effect of scopolamine on recognition memory. To describe the scopolamine-injected subjects' data, the authors constructed a new model of 2-process recognition that includes the A. P. Yonelinas (1994) model as a limiting case. The model analysis suggests that scopolamine affected both familiarity and recollection. In particular, scopolamine did not affect the frequency with which recollection took place, but rather, affected the amount of recollected information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpretation of way-finding healthcare symbols by a multicultural population: Navigation signage design for global health

The interpretation of way-finding symbols for healthcare facilities in a multicultural community was assessed in a cross-sectional study. One hundred participants recruited from Al Ain city in the United Arab Emirates were asked to interpret 28 healthcare symbols developed at Hablamos Juntos (such as vaccinations and laboratory) as well as 18 general-purpose symbols (such as elevators and restrooms). The mean age was 27.6 years (16–55 years) of whom 84 (84%) were females. Healthcare symbols were more difficult to comprehend than general-purpose signs. Symbols referring to abstract concepts were the most misinterpreted including oncology, diabetes education, outpatient clinic, interpretive services, pharmacy, internal medicine, registration, social services, obstetrics and gynecology, pediatrics and infectious diseases. Interpretation rates varied across cultural backgrounds and increased with higher education and younger age. Signage within healthcare facilities should be tested among older persons, those with limited literacy and across a wide range of cultures.     

Identification of leek-moth and diamondback-moth frass volatiles that stimulate parasitoid,Diadromus pulchellus

Acrolepiopsis assectella andPlutella xylostella frass volatiles, trapped on Tenax GC, were examined by capillary gas chromatography. In both moths, the same three disulfides, dimethyl, dipropyl, and methyl propyl, were the most abundant substances, but in different proportions. The synthetic disulfides elicited the same behavioral response by the parasitoid,Diadromus pulchellus as frass. The plant origin of these substances is discussed.     

A description of phase inversion behaviour in agitated liquid-liquid dispersions under the influence of the Marangoni effect

The influence of the Marangoni effect on phase inversion behaviour is examined by integrating a microscopic study of the drop coalescence process, in which thin film drainage in the presence of insoluble surfactant occurs, into a macroscopic phase inversion model which has been developed previously using a Monte Carlo technique. This is achieved via an immobility factor, obtained from a comparison of the film drainage times for surfactant-laden systems and surfactant-free systems as a function of the drop approach velocity, surface Péclet number, initial surfactant concentration and the Hamaker constant, which is then used to modify the coalescence probability in the phase inversion model. On the one hand, the results indicate that the Marangoni effect removes any influence that the viscosity ratio has on phase inversion due to immobilisation of the interface, thus shielding the flow in the film from the effects of the flow in the dispersed phase; the point at which phase inversion occurs therefore tends towards equivolume holdups with the addition of surfactant. On the other hand, when comparisons are made with pure systems in which surfactant is absent, the system is seen to be either stabilised or de-stabilised from inversion depending on the viscosity ratio of the system. This is attributed to the influence of surfactant on the dispersion morphologies on either side of the inversion (i.e. water-in-oil dispersions and oil-in-water dispersions) and depends on the dispersed phase holdup; the Marangoni effect is felt stronger when the dispersed phase holdup is low.     

Design and fabrication of 3D‐plotted polymeric scaffolds in functional tissue engineering

Regenerating the load‐bearing tissues requires 3D scaffolds that balance the temporary mechanical function with the biological requirements. In functional tissue engineering, designing scaffolds with biomimetic mechanical properties could promote tissue ingrowth since the cells are sensitive to their local mechanical environment. This work aims to design scaffolds that mimic the mechanical response of the biological tissues under physiological loading conditions. Poly(L ‐lactide) (PLLA) scaffolds with varying porosities and pore sizes were made by the 3D‐plotting technique. The scaffolds were tested under unconfined ramp compression to compare their stress profile under load with that of bovine cartilage. A comparison between the material parameters estimated for the scaffolds and for the bovine cartilage based on the biphasic theory enabled the definition of an optimum window for the porosity and pore size of these constructs. Moreover, the finite element prediction for the stress distribution inside the scaffolds, surrounded by the host cartilaginous tissue, demonstrated a negligible perturbation of the stress field at the site of implantation. The finite element modeling tools in combination with the developed methodology for optimal porosity/pore size determination can be used to improve the design of biomimetic scaffolds. POLYM. ENG. SCI., 47:608–618, 2007. © 2007 Society of Plastics Engineers.     

Density Displays for Data Stream Monitoring

In many business applications, large data workloads such as sales figures or process performance measures need to be monitored in real‐time. The data analysts want to catch problems in flight to reveal the root cause of anomalies. Immediate actions need to be taken before the problems become too expensive or consume too many resources. In the meantime, analysts need to have the “big picture” of what the information is about. In this paper, we derive and analyze two real‐time visualization techniques for managing density displays: (1) circular overlay d isplays which visualize large volumes of data without data shift movements after the display is full, thus freeing the analyst from adjusting the mental picture of the data after each data shift; and (2) variable resolution density displays which allow users to get the entire view without cluttering. We evaluate these techniques with respect to a number of evaluation measures, such as constancy of the display and usage of display space, and compare them to conventional d isplays with periodic shifts. Our real time data monitoring system also provides advanced interactions such as a local root cause analysis for further exploration. The applications using a number of real‐world data sets show the wide applicability and usefulness of our ideas.     

Modelling the removal of organic vehicle from ceramic or metal mouldings: The effect of gas permeation on the incidence of defects

A shrinking undegraded core and a porous outer layer result, if the organic vehicle used for shaping ceramic or metal powder mouldings recedes in the interparticle space of the moulded body during pyrolysis. In the present work, a numerical model has been used which simulates the undegraded shrinking core situation and quantifies degradation of the organic vehicle and the diffusion of the resulting products in solution in the organic phase during pyrolysis of a ceramic moulding. This model is extended to include gaseous mass transport in the porous outer layer for a moulding in the shape of an infinite cylinder. The effect of resistance to gaseous mass transport in the porous outer region on defects originating in inner regions was estimated. It is shown that the greatest obstruction to mass transport is diffusion of degradation products in solution in the organic phase. However, the permeability coefficient for gas transport in the outer region begins to affect the critical heating rate required for avoidance of defects only when it is less than 10^–15m².Nomenclature C Concentration,C=C (r, t), based on the total volume of ceramic suspension - d Effective molecular diameter of alphamethylstyrene - D Diffusion coefficient,D=D (C, T) - e Porosity of powder - E Activation energy for thermal degradation - h Remaining weight fraction of polymer - H_vap Enthalphy of vaporization - i Node number - I Pre-exponential constant in Equation 13 - j Time step - K _p Permeability coefficient - K ₀ Specific rate constant - m Mass of monomer displaced - M Mass of one alphamethylstyrene molecule - P Monomer vapour pressure - P _s Monomer vapour pressure at outer surface of the cylinder - P ₁ ⁰ Vapour pressure of monomer over its pure liquid - Q Rate of production of monomer, based on the total volume of ceramic suspension - r Radius of the cylinder - r _j Distance from central axis to the inner surface of the porous layer at time stepj - r ₀ Initial radius of the cylinder - R Universal gas constant - S ₀ Specific surface area of powder per unit solid volume - t Time - T Absolute temperature - T _c Temperature at maximum vapour pressure of monomer and atZ _c - V Volume of monomer - V _c Ceramic volume fraction - V _p Polymer volume fraction - w Mass of monomer stored in the porous annulus - Z Heating rate - Z _c Critical heating rate - ₁ Volume fraction of monomer in the polymer-monomer solution - Viscosity of the monomer vapour - _p Density of the polymer - Polymer-monomer interaction constant