Influence of the Synthesis Method on the Preparation Composites Derived from TiO2-LDH for Phenol Photodegradation

Three different TiO2 catalysts are prepared using different methods. MgAl-CO32− layered double hydroxides (LDH) were obtained by the sol-gel method. In the preparation of the composites, the three photocatalysts were combined with LDH following different methodologies. The composites were characterized using X-ray diffraction (XRD), specific surface area (SA), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the preparation of the composites was evaluated by analyzing their photocatalytic activity against phenol as a model organic pollutant under UV irradiation. The photocatalytic activity of the composites improves when the chemical interaction, determined by XPS, between the TiO2 and the LDH decreases. The same happens when the ratio of the anatase-rutile phases, determined by XRD, approaches optimum (80:20%). The effect of the composite concentration in the solution (0.5–2.0 g/L) was investigated, and the light-shielding phenomenon due to high composite concentration decreases the phenol photodegradation. The reduction of photocatalytic activity in reuse cycles is due to loss and partial deactivation of the material. The elimination of phenol is attributed primarily to the photocatalytic process due to the generation of ●OH radicals and to a lesser extent the adsorption process also present in the samples

Temperature dependence of the anomalous effective action of fermions in two and four dimensions

The temperature dependence of the anomalous sector of the effective action of fermions coupled to external gauge and pseudo-scalar fields is computed at leading order in an expansion in the number of Lorentz indices in two and four dimensions. The calculation preserves chiral symmetry and confirms that a temperature dependence is compatible with axial anomaly saturation. The result checks soft-pions theorems at zero temperature as well as recent results in the literature for the pionic decay amplitude into static photons in the chirally symmetric phase. The case of chiral fermions is also considered.Comment: RevTex, 19 pages, no figures. References adde

A simulation analysis of an influenza vaccine production plant in areas of high humanitarian flow. A preliminary study for the region of norte de santander (colombia)

The production of vaccines of biological origin presents a tremendous challenge for re-searchers. In this context, animal cell cultures are an excellent alternative for the isolation and production of biologicals against several viruses, since they have an affinity with viruses and a great capacity for their replicability. Different variables have been studied to know the system’s ideal parameters, allowing it to obtain profitable and competitive products. Consequently, this work fo-cuses its efforts on evaluating an alternative for producing an anti‐influenza biological from MDCK cells using SuperPro Designer v8.0 software. The process uses the DMEN culture medium supple-mented with nutrients as raw material for cell development; the MDCK cells were obtained from a potential scale‐up with a final working volume of 500 L, four days of residence time, inoculum volume of 10%, and continuous working mode with up to a total of 7400 h/Yr of work. The scheme has the necessary equipment for the vaccine’s production, infection, and manufacture with yields of up to 416,698 units/h. In addition, it was estimated to be economically viable to produce recom-binant vaccines with competitive prices of up to 0.31 USD/unit

Herschel/HIFI observations of molecular emission in protoplanetary nebulae and young planetary nebulae

We performed Herschel/HIFI observations of intermediate-excitation molecular lines in the far-infrared/submillimeter range in a sample of ten protoplanetary nebulae and young planetary nebulae. The high spectral resolution provided by HIFI yields accurate measurements of the line profiles. The observation of these high-energy transitions allows an accurate study of the excitation conditions, particularly in the warm gas, which cannot be properly studied from the low-energy lines. We have detected FIR/sub-mm lines of several molecules, in particular of 12CO, 13CO, and H2O. Emission from other species, like NH3, OH, H2^{18}O, HCN, SiO, etc, has been also detected. Wide profiles showing sometimes spectacular line wings have been found. We have mainly studied the excitation properties of the high-velocity emission, which is known to come from fast bipolar outflows. From comparison with general theoretical predictions, we find that CRL 618 shows a particularly warm fast wind, with characteristic kinetic temperature Tk >~ 200 K. In contrast, the fast winds in OH 231.8+4.2 and NGC 6302 are cold, Tk ~ 30 K. Other nebulae, like CRL 2688, show intermediate temperatures, with characteristic values around 100 K. We also discuss how the complex structure of the nebulae can affect our estimates, considering two-component models. We argue that the differences in temperature in the different nebulae can be due to cooling after the gas acceleration (that is probably due to shocks); for instance, CRL 618 is a case of very recent acceleration, less than ~ 100 yr ago, while the fast gas in OH 231.8+4.2 was accelerated ~ 1000 yr ago. We also find indications that the densest gas tends to be cooler, which may be explained by the expected increase of the radiative cooling efficiency with the density.Comment: 24 pages, 31 figure

Proximity effects on nuclear spin-spin coupling constants. 1. 1J(CH) couplings in the vicinity of an atom bearing lone pairs

Proximity effects on 1J(CH) couplings are studied from a theoretical point of view in the following systems: CH4/FH (A) and H2O/HCN (B) which form dimers by hydrogen-bond interactions. 1J(CH) couplings for different intermolecular distances are calculated for the C - H bond facing the atom bearing lone pairs. While in the former system, this coupling is increased owing to the proximity to the F atom; in the latter this coupling is decreased owing to the proximity to the O atom. These opposite trends are accompanied by slight shortening and lengthening, respectively, of the corresponding C - H bond lengths. As part of this work, measurements of 1J(CH) couplings in 9-(1,3-dioxolan-2-yl)-1,2,3,4-tetrafluorotriptycene (I) and 1-formyl-2-hydroxy-8-fluoronaphthalene (II) and 1J(NH) in o-fluorobenzamide (III), showing proximity effects as those described above are carried out. These results suggest that 1J(XH) couplings are adequate probes to distinguish two different types of X-H⋯Y hydrogen bonds. © 1994 American Chemical Society.Fil:Vizioli, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:De Ruiz Azúa, M.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Giribet, C.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

11 hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient SSS17a was discovered in the galaxy NGC 4993. While the gravitational wave data indicate GW170817 is consistent with the merger of two compact objects, the electromagnetic observations provide independent constraints of the nature of that system. Here we synthesize all optical and near-infrared photometry and spectroscopy of SSS17a collected by the One-Meter Two-Hemisphere collaboration. We find that SSS17a is unlike other known transients. The source is best described by theoretical models of a kilonova consisting of radioactive elements produced by rapid neutron capture (the r-process). We find that SSS17a was the result of a binary neutron star merger, reinforcing the gravitational wave result.Comment: 21 pages, 4 figures, accepted to Scienc

Urinary Excretion of Mimosine Metabolites by Hair Sheep Fed Foliage of \u3cem\u3eLeucaena leucocephala\u3c/em\u3e

Leucaena leucocephala is an adapted legume widely distributed in the tropical regions of Mexico. The high crude protein content of leucaena leaves renders it appropriate for ruminant feeding under commercial conditions. However, the foliage contains the non-protein amino acid mimosine, which, if consumed in high amounts, may induce toxicity in animals which have not previously consumed the legume or without microorganisms capable of degrading mimosine and its derivatives 2,3-DHP (dihydroxypyridine) and 3,4-DHP (Hammond 1995, Palmer et al. 2010, Dalzell et al. 2012). Barros-Rodríguez et al. (2012) found that dry matter intake and weight gain were reduced when sheep grazed paddocks with 55,000 plants of leucaena per hectare. Early work in Australia led to the isolation of Synergistes jonesii, an anaerobic bacterium able to degrade 3,4-DHP and 2,3-DHP to non-toxic compounds (Allison et al. 1992). In Mexico, the presence of this microorganism in the rumen has not yet been confirmed. Inoculation of non-accustomed animals with rumen liquor of ruminants adapted to the consumption of leucaena can reduce the impact of mimosine and its metabolites on animal health (Ghosh et al. 2009; Palmer et al. 2010). The aim of the present work was to evaluate the effects of transferring rumen liquor of cows adapted to the consumption of L. leucocephala to sheep without experience of consumption, on urinary excretion of 3.4-DHP and 2.3-DHP by means of a colorimetric technique

Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

On 2017 August 17, gravitational waves were detected from a binary neutron star merger, GW170817, along with a coincident short gamma-ray burst, GRB170817A. An optical transient source, Swope Supernova Survey 17a (SSS17a), was subsequently identified as the counterpart of this event. We present ultraviolet, optical and infrared light curves of SSS17a extending from 10.9 hours to 18 days post-merger. We constrain the radioactively-powered transient resulting from the ejection of neutron-rich material. The fast rise of the light curves, subsequent decay, and rapid color evolution are consistent with multiple ejecta components of differing lanthanide abundance. The late-time light curve indicates that SSS17a produced at least ~0.05 solar masses of heavy elements, demonstrating that neutron star mergers play a role in r-process nucleosynthesis in the Universe.Comment: Accepted to Scienc

Managing ethnic conflict : the menu of institutional engineering

The debate on institutional engineering offers options to manage ethnic and other conflicts. This contribution systematically assesses the logic of these institutional designs and the empirical evidence on their functioning. Generally, institutions can work on ethnic conflict by either accommodating (“consociationalists”) or denying (“integrationists”) ethnicity in politics. Looking at individual and combined institutions (e.g. state structure, electoral system, forms of government), the literature review finds that most designs are theoretically ambivalent and that empirical evidence on their effectiveness is mostly inconclusive. The following questions remain open: a) Is politicized ethnicity really a conflict risk? b) What impact does the whole “menu” (not just single institutions) have? and c) How are effects conditioned by the exact nature of conflict risks