Numerical investigation of transient heat and mass transfer in a parallel-flow liquid-desiccant absorber

Liquid desiccant systems have received significant attention as a way to reduce latent loads. Tests of liquid desiccant systems in humid climates have shown significant reductions in energy consumption. As moisture in the air is absorbed at the dehumidifier, the temperature of the liquid desiccant increases due to the addition of heat from the enthalpy of condensation of the water vapor. Thus, the coupled effects of heat and mass transfer are relevant for these applications. A two-dimensional mathematical model of the transient heat and mass transfer for an absorber where a thin film of liquid desiccant flows down its walls and dehumidifies the air in parallel-flow configuration is developed and the dynamics of the modeled system are analyzed.     

3,5‐Dimethyl‐4‐[(E)‐(2‐nitrophenyl)diazenyl]‐1‐(2,3,4,5,6‐pentafluorophenyl)‐1H‐pyrazole

The title compound, C₁₇H₁₀F₅N₅O₂, is described and compared with its 4‐nitrophenyl isomer [Bustos, Sánchez, Schott, Alvarez‐Thon & Fuentealba (2007). Acta Cryst. E 63 , o1138–o1139]. The title molecule presents its nitro group split into two rotationally disordered components, which in conjunction with the rotation of the `unclamped' rings constitute the main molecular differences. Packing is directed by a head‐to‐tail type `I' C—F...F—C interaction, generating double‐chain strips running along [100]. These substructures are interlinked by a variety of weak F...F, O...F, F...π and O...π interactions.     

PAST AND FUTURE MANAGEMENT OF A COLLAPSED FISHERY: THE BAY OF BISCAY ANCHOVY

Abstract We analyze the efficiency of the international management of the Bay of Biscay anchovy. While a sharing agreement between France and Spain has been in place since 1992, the fish stock collapsed in 2005 and the fishery closed from 2005 to spring 2010. We consider differences in production technologies between both countries and calibrate our model using data from 1987 to 2009. Our results suggest two sources of rent dissipation under the existing sharing agreement: inefficient quota allocation and production inefficiencies due to inflexible national regulations. We discuss several alternatives to improve management.     

Synthesis and direct interactions of silver colloidal nanoparticles with pollutant gases

Silver nanoparticles (NPs) were synthesized in organic solvents. Spontaneous reduction of silver salts takes place in N,N′-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) at room temperature. The formed colloids are not stable without a stabilizing agent, hence rarely used, and inexpensive organic molecules (β-cyclodextrin and cholic acid) were used as surface modifiers in DMF. The stabilization was successful; the Ag NPs remained stable for more than 3 months. Additionally, Ag NPs were prepared using Ag-2-ethylhexanoate and Na-citrate as capping agent in DMSO. The resulting NPs are stable, of 4.4 nm average size, and at the same time reactive for catalytic purposes. The interaction of Ag NPs with pollutant atmospheric gases (NO and SO₂) was studied. UV–visible spectra show the oxidation of silver and the very efficient reduction of NO at room temperature. SO₂ molecules are adsorbed on the NPs surface, causing their aggregation and precipitation.     

On green potentials with bounded square integral means in the unit disc

The paper is devoted to investigation of the class of Green potentials in the unit disc of the complex plane, which possess bounded square integral means.     

Efficient synthesis of branched poly(acrylic acid) derivatives via postpolymerization modification

The utility of pentafluorophenyl esters for the selective introduction of functional units and branch points in well-defined poly(acrylic acid) (PAA) derivatives is demonstrated using a combination of controlled radical polymerization and postpolymerization modification. Reversible addition-fragmentation chain transfer enables the synthesis of well-defined copolymers—poly(pentafluorophenyl acrylate-co-tert-butyl acrylate)—with the active ester repeat units serving as attachment points for reaction with primary amines, specifically tris(2-(t-butoxycarbonyl)ethyl)methyl amine (Behera's amine). Deprotection using trifluoroacetic acid removes both the backbone and side chain t-butyl esters to give a series of branched PAA derivatives containing novel tricarboxylic acid side chains that are well suited to complexation and multidentate interactions. Surprisingly, the active ester homopolymer is shown to have the highest reactivity with Behera's amine when compared to copolymers with lower incorporation of pentafluorophenyl esters, suggesting an intriguing interplay of neighboring group effects and steric interactions. The ability to tune the efficiency of postpolymerization modification gives a library of PAA derivatives.     

Broad‐Band Time‐Resolved Near Infrared Spectroscopy in the TJ‐II Stellarator

First experimental results on broad‐band, time‐resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ‐II Stellarator. Experimental set‐up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time‐resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ‐II are discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Resonant X-ray diffraction of self-assembled epitaxial systems: From direct to complementary chemical information

In this work we depict schematically the use of resonant (anomalous) X-ray diffraction as a tool to directly probe strain and composition of self-assembled semiconductor islands. By employing a direct analysis at the Eu L₃ edge its composition gradient is quantified for EuTe:SnTe capped islands. Projection maps are proposed to visualize the results, providing an alternative capability to infer quantum dot properties. A more complex methodology is applied to the study of InP:GaAs islands, in which complementary anomalous measurements are performed. For this system the number of samples analyzed allows us to extract the activation energy for Ga adatoms diffusion from the substrate to the islands.     

Application and Modification of Cyclometalated Ruthenium(II) Complex [Ru(o-C6H4-2-C5H4N)- (MeCN)4]PF6 for Atom Transfer Radical Polymerization

Polymerizations of n-butyl acrylate (BA), methyl methacrylate (MMA) and styrene (St) were promoted by the Ru(II) cyclometalated complex with labile MeCN ligand in the presence of Al(OiPr)₃. The polymerization proceeds via radical mechanism and requires the loss of MeCN ligand. The poor control over the polymerizations can be explained in terms of the traditional ATRP scheme. However, the controllability may be significantly improved by addition of reducing SnCl₂. Mechanism of the process is proposed.