Thermodynamics of metal reactants for ammonia synthesis from steam,nitrogen and biomass at atmospheric pressure

Catalytic ammonia synthesis at approximately 30 MPa and 800 K consumes about 5% of the global annual natural gas production causing significant CO₂ emissions. A conceptual solar thermochemical reaction cycle to produce NH₃ at near atmospheric pressure without natural gas is explored here and compared to solar thermochemical steam/air reforming to provide H₂ used in the Haber‐Bosch process for NH₃ synthesis. Mapping of Gibbs free energy planes quantifies the tradeoff between the yield of N₂ reduction via metal nitridation, and NH₃ liberation via steam hydrolysis vs. the temperatures required for reactant recovery from undesirably stable metal oxides. Equilibrium composition simulations suggest that reactants combining an ionic nitride‐forming element (e.g., Mg or Ce) with a transition metal (e.g., MgCr₂O₄, MgFe₂O₄, or MgMoO₄) may enable the concept near 0.1 MPa (at maximum 64 mol % yield of Mg₃N₂ through nitridation of MgFe₂O₄ at 1,300 K, and 72 mol % of the nitrogen in Mg₃N₂ as NH₃ during hydrolysis at 500 K). © 2011 American Institute of Chemical Engineers AIChE J, 58: 3203–3213, 2012     

Simulating the Feasibility of Using Liquid Micro-Jets for Determining Electron–Liquid Scattering Cross-Sections

The extraction of electron–liquid phase cross-sections (surface and bulk) is proposed through the measurement of (differential) energy loss spectra for electrons scattered from a liquid micro-jet. The signature physical elements of the scattering processes on the energy loss spectra are highlighted using a Monte Carlo simulation technique, originally developed for simulating electron transport in liquids. Machine learning techniques are applied to the simulated electron energy loss spectra, to invert the data and extract the cross-sections. The extraction of the elastic cross-section for neon was determined within 9% accuracy over the energy range 1–100 eV. The extension toward the simultaneous determination of elastic and ionisation cross-sections resulted in a decrease in accuracy, now to within 18% accuracy for elastic scattering and 1% for ionisation. Additional methods are explored to enhance the accuracy of the simultaneous extraction of liquid phase cross-sections.     

Clay Bodies: Crafting the Future with 3D Printing

People have been using clay to make objects and shelters since time immemorial; but could it also be a key material of the future? San Francisco-based xyqmake-tank’ Emerging Objects has been experimenting with the use of clay in 3D printing, with sophisticated codes producing woven and textured forms and mixing different clays together. The studio's cofounders Ronald Rael and Virginia San Fratello here present these projects, as well as offering a potted history of clay's use and nature. Given its re-resistance and thermal qualities, the benefits of eventually applying such techniques on an architectural scale are clear.     

Automatic correction of level set based subvoxel precise centerlines for virtual colonoscopy using the colon outer wall

Virtual colonoscopy (VC) is becoming a more prevalent method to detect and diagnose colorectal cancer. An essential component of using VC to detect cancerous polyps, especially in conjunction with computer-aided diagnosis, is the accurate calculation of the centerline of the colon. While the colon is often modeled as a simple cylinder, the amount of colonic distention may vary between patients and within the same patient often causing loops and multiple disconnected segments to be present in the colon segmentation. These variations have caused previous centerline algorithms to fail to capture a complete and accurate centerline for all colons. We have developed an automatic method to determine from a computed tomography (CT) VC a subvoxel precise centerline that is accurate even in cases of over-distended or under-distended colons. In this algorithm, the loops in the colon caused by over-distention are detected and removed when the centerline calculation is performed. Also, a newly developed method for the detection and segmentation of the outer wall of the colon is used to connect collapsed portions of the colon where the lumen segmentation fails to produce a continuous centerline. These two methods allow for a complete and accurate centerline to be calculated in uniformly distended colons as well as in colons containing segments which are over-distended and/or under-distended. We have demonstrated successfully the effectiveness of our algorithm on 50 cases, 25 of which resulted in erroneous solutions by previous centerline algorithms due to variability in the colon distention.     

Behavioral medicine: St. Louis style.

Describes a unique multidisciplinary division in which 8 clinical programs are all administered by psychologists working in a university medical center setting. The increasingly complex environment of a university medical center is discussed in terms of academic mission, competitiveness of health care, and professional roles. The development of this division is reviewed in relation to a number of critical issues, such as organizational structure, academic vs clinical demands, business operations, and 1 version of a scientist–practitioner model in practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

EFFICIENT NEW SYNTHESES OF POLYCYCLIC AROMATIC HYDROCARBON ORTHO-QUINONES AND THEIR 2′-DEOXYRIBONUCLEOSIDE ADDUCTS

Three mechanisms have been proposed to explain the carcinogenic activities of polycyclic aromatic hydrocarbons (PAHs). On the basis of the nature of the active metabolites involved, they may be termed: the diol epoxide mechanism, the quinone mechanism, and the radical-cation mechanism. In connection with studies to evaluate the relative importance of these pathways, we required practical methods for the syntheses of the active PAH metabolites involved. We now report efficient new synthesis of the o-quinones of benzo[a]pyrene (BPQ), 7,12-dimethylbenz[a]anthracene (DMBAQ), and benz[a]anthracene (BAQ). These quinones are convenient synthetic precursors of the related o-catechols, trans-dihydrodiols, and diol epoxides, as well as the stable adducts of the o-quinones with 2-deoxyadenosine and 2′-deoxyguanosine.     

Transport of Gellan Gum Microbeads in Soil Columns of Various Grain Size Distributions

The transport of gellan gum microbeads as potential cell carriers was investigated in horizontal columns packed with different grain size classes of gravel (2–16 mm) and sand (0.25–2 mm). A suspension of microbeads was pulsed into each column for 6 h, followed by injection of water for 42 h. In general, the total amount of microbeads travelling across a given section of the column increased with injection time but decreased towards the column outlet, varying as a direct function of grain size. The results of this study demonstrate the feasibility of the transport of gellan gum microbeads through medium sand to medium gravel across distances up to 110 cm.     

Mechanism of cytotoxicity and cellular uptake of lipophilic inert dinuclear polypyridylruthenium(II) complexes

The accumulation, uptake mechanism, cytotoxicity, cellular localisation of—and mode of cell death induced by—dinuclear ruthenium(II) complexes ΔΔ/ΛΛ‐[{Ru(phen)₂}₂{μ‐bb_n}]⁴⁺ (Rubb_n), where phen is 1,10‐phenanthroline, bb_n is bis[4(4′‐methyl‐2,2′‐bipyridyl)]‐1,n‐alkane (n=2, 5, 7, 10, 12 or 16), and the corresponding mononuclear complexes containing the bb_n ligands, were studied in L1210 murine leukaemia cells. Cytotoxicity increased with linker chain length, and the ΔΔ‐Rubb₁₆ complex displayed the highest cytotoxicity of the series, with an IC₅₀ value of 5 μM , similar to that of carboplatin in the L1210 murine leukaemia cell line. Confocal microscopy and flow cytometry studies indicated that the complexes accumulate in the mitochondria of L1210 cells, with the magnitude of cellular uptake and accumulation increasing with linking chain length in the bb_n bridge of the metal complex. ΔΔ‐Rubb₁₆ entered the L1210 cells by passive diffusion (with a minor contribution from protein‐mediated active transport), inducing cell death via apoptosis. Additionally, metal‐complex uptake in leukaemia cells was approximately 16‐times that observed in healthy B cells highlighting that the bb_n series of complexes may have potential as selective anticancer drugs.