Van der Waals torque induced by external magnetic fields

We present a method for inducing and controlling van der Waals torques between two parallel slabs using a constant magnetic field. The torque is calculated using the Barash theory of dispersive torques. In III-IV semiconductors such as $InSb$, the effect of an external magnetic field is to induce an optical anisotropy, in an otherwise isotropic material, that will in turn induce a torque. The calculations of the torque are done in the Voigt configuration, with the magnetic field parallel to the surface of the slabs. As a case study we consider a slab made of calcite and a second slab made of $InSb$. In the absence of magnetic field there is no torque. As the magnetic field increases, the optical anisotropy of $InSb$ increases and the torque becomes different from zero, increasing with the magnetic field. The resulting torque is of the same order of magnitude as that calculated using permanent anisotropic materials when the magnetic fields is close to 1 T.Comment: to appear in Journal of Applied Physic

Corrosion Performance of Conversion Treatments for Electrogalvanised Steel Sheet

Chromate conversion treatments have been widely used due to their excellent corrosion resistance properties; however, their use is increasingly restricted because of the highly toxic chromic acid solutions required, with consequent effluent disposal and ecological problems. The removal of these toxic chemicals is considered a priority within most of the developed countries. In this work, the corrosion resistance of different alternative pretreatments applied on electrogalvanised steel sheet: 1) Cr(III) and Zr complexes layer, 2) Ce(III) layer, 3) Ce(III)/Ce(IV) double layer, 4) Cr(VI) chromating was investigated, and its results compared with those from the tests performed using bare electrogalvanized steel sheets as a substrate. These samples were exposed to aerated 0.05 mol/L NaCl or 0.1 mol/L Na2SO4 solutions. The electrochemical behavior of samples was studied by electrochemical techniques. For three days of immersion in the solution test, the experimental results have shown that, compared with the Cr(VI) protective properties, the Cr(III) + Zr complex layer presented similar performance. Even though the initial corrosion resistance was offered by the Ce(III) and Ce(VI)/Ce(III) conversion coatings was relatively good, it quickly decreased as a function of the exposure time.Fil: Di Sarli, Alejandro Ramón. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Elsner, Cecilia Ines. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería; ArgentinaFil: Palomino, L. E. M.. Universidade de Sao Paulo; BrasilFil: Tomachuk, C. R.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin

Analysis and characterization of neutron scattering of a Linear Accelerator (LINAC) on medical applications.

In several theoretical and experimental studies, the topic of the undesirable generation of photoneutrons in rooms where a linear accelerator (LINAC) operates has been discussed. When energies above 10 MeV are used to produce X-rays and give radiotherapy treatment to patients resulting in additional radiation to patients. Accordingly, an analysis and characterization of the neutron scattering distribution on different zones in a treatment room contributes to evaluate the radiological health risk to patients, technical and other workers involved in treatment. For the evaluation, a device developed at the PAD-IFUNAM formed by a CR-39 detector enclosed by two 3mm thick acrylic plates was employed. To avoid environmental contamination, the CR-39 and the acrylics plates are enclosed in a round plastic box. Sixteen of these devices were settled in different places inside the treatment room, where a linear accelerator is used. The results show a significant concentration of neutron scattering in areas near the head of irradiation. The recommendation will be to evaluate the neutron scattering concentration in all rooms that’s operates a LINAC in order to verify the radiological health risk and to mitigate the neutron scattering when concentration levels are to high like those in our case, in order to avoid unnecessary exposition to patients and personnel in general

Site-to-site interdomain communication may mediate different loss-of-function mechanisms in a cancer-associated NQO1 polymorphism

Disease associated genetic variations often cause intracellular enzyme inactivation, dysregulation and instability. However, allosteric communication of mutational effects to distant functional sites leading to loss-of-function remains poorly understood. We characterize here interdomain site-to-site communication by which a common cancer-associated single nucleotide polymorphism (c.C609T/p.P187S) reduces the activity and stability in vivo of NAD(P)H:quinone oxidoreductase 1 (NQO1). NQO1 is a FAD-dependent, two-domain multifunctional stress protein acting as a Phase II enzyme, activating cancer pro-drugs and stabilizing p53 and p73a oncosuppressors. We show that p.P187S causes structural and dynamic changes communicated to functional sites far from the mutated site, affecting the FAD binding site located at the N-terminal domain (NTD) and accelerating proteasomal degradation through dynamic effects on the C-terminal domain (CTD). Structural protein:protein interaction studies reveal that the cancer-associated polymorphism does not abolish the interaction with p73a, indicating that oncosuppressor destabilization largely mirrors the low intracellular stability of p.P187S. In conclusion, we show how a single disease associated amino acid change may allosterically perturb several functional sites in an oligomeric and multidomain protein. These results have important implications for the understanding of loss-of-function genetic diseases and the identification of novel structural hot spots as targets for pharmacological intervention

Gamma Ray Bursts: Observations and Theoretical Conjectures

Gamma Ray Bursts (GRBs) are short bursts of very high energy photons which were discovered in the late 1960s. Ever since their discovery, scientists have wondered about their origin. Nowadays it is known that they originate outside the Milky Way because of their high red shift rst measured in the afterglows thanks to the Beppo-SAX satellite and ground-based observations. However, theoreticians still do not agree about the mechanism that generates the bursts, and different competing models are animatedly debated. Current GRB experiments include the Swift satellite and the Pierre Auger Observatory that could detect GRBs with an increase of the background. A forthcoming dedicated experiment is GLAST, a satellite observatory for detecting gamma rays with energies up to 300 GeV, whose launch is scheduled for early 2008

Uso de hidrolizados de pescado en la acuicultura: una revisión de algunos resultados beneficiosos en dietas acuícolas

Las industrias pesqueras y de acuicultura generan, cada año, un conjunto de residuos o desechos que incluyen piel, cabeza, vísceras, recortes y espinazos, representando más del 60% en volumen productivo. Estos residuos tienen altos contenidos de proteínas, y normalmente son procesados en productos de bajo valor comercial, como alimentos para animales, harina de residuos y fertilizantes. En los últimos años, se han venido desarrollando tecnologías para el aprovechamiento de éstos residuos y convertirlos en bioproductos de mayor valor agregado, como son los hidrolizados de proteínas, con interesantes aplicaciones en la alimentación animal. Los hidrolizados proteicos de pescado son productos obtenidos de la degradación enzimática o química de las proteínas de pescado en péptidos más pequeños, aminoácidos libres y nucleótidos, obteniéndose un alto contenido proteico con buen balance de aminoácidos, alta digestibilidad y mejor aprovechamiento de sus nutrientes. La inclusión de éstos hidrolizados en los alimentos acuícolas puede mejorar el crecimiento y la eficiencia alimentaria de los organismos acuáticos en cultivo. Este artículo presenta una revisión sobre investigaciones de la inclusión de hidrolizados proteicos de pescado en dietas experimentales para peces, crustáceos, moluscos y algas, y los efectos en los desempeños productivos, en los últimos veinte años

From hyperextended rift to convergent margin types: mapping the outer limit of the extended Continental Shelf of Spain in the Galicia area according UNCLOS Art. 76

European Geosciences Union General Assembly (2017. Viena)Spain presented on 11 May 2009 a partial submission for delimiting the extended Continental Shelf in respect to the area of Galicia to the Commission on the Limits of the Continental Shelf (CLCS). The Galicia margin represents an example of the transition between two different types of continental margins (CM): a western hyperpextended margin and a northern convergent margin in the Bay of Biscay. The western Galicia Margin (wGM 41º to 43º N) corresponds to a hyper-extended rifted margin as result of the poly-phase development of the Iberian-Newfoundland conjugate margin during the Mesozoic. Otherwise, the north Galicia Margin (nGM) is the western end of the Cenozoic subduction of the Bay of Biscay along the north Iberian Margin (NIM) linked to the Pyrenean-Mediterranean collisional belt.Instituto Geológico y Minero de España, EspañaCentro Oceanográfico de Málaga, Instituto Español de Oceanografía, EspañaInstituto Hidrográfico de la Marina, Españ

Mapping giant mass transport deposits (MTDs) for delineating the extended Continental Shelf of Spain to the West of Canary Islands according UNCLOS Art. 76

European Geosciences Union General Assembly (2017. Viena)On 19 December 2014, Spain presented a third partial submission for the delineation of the Extended Continental in the area west of the Canary Islands to the Commission on the Limits of the Continental Shelf (CLCS) according to the United Nations Convention on the Law of Sea (UNCLOS). The Canary Islands are located within a NE-SW 1,350 km long ridge of hotspot-inferred volcanic islands and seamounts (composed by more of 100, from Lars to Tropic seamounts). This submission has been documented with an extensive dataset specifically obtained for the project during ten oceanographic cruises between 2010 and 2014 aboard the Spanish research vessels Hespérides, Sarmiento de Gamboa and Miguel Oliver. This new dataset allows to investigate an area of 440,000 km2 with acoustic backscatter images and multibeam echosounder bathymetric (MBES) data (Simrad EM-12, EM-120 and EM-302, and Atlas HYDROSWEEP DS), a dense network of 65,800 km of very-high resolution (VHR) seismic lines (including chirp parametric source TOPAS PS-18 and Atlas PARASOUND P-35) and 4,471 km of multichannel seismic reflection lines (MCS) acquired with an array of air-guns yielding a total volume of 4,600 inch3 (75.38 L) and a 3,500 m long streamer composed of 280 channels.Instituto Geológico y Minero de España, EspañaInstituto Español de Oceanografía, EspañaInstituto Hidrográfico de la Marina, Españ

Influencia de la composición de la dieta sobre el perfil de ácidos grasos y la expresión génica en tejidos adiposo, muscular y hepático de cerdos ibéricos

La composición de los tejidos animales es determinante en la calidad de los productos y está influida por varios factores como la dieta, el tipo genético, la edad y el sexo. En este trabajo se ha evaluado el efecto de la composición de ácidos grasos (AG) de la dieta de cerdos ibéricos en fase de cebo, sobre la composición de AG de los tejidos y la transcripción de genes codificantes para enzimas clave del metabolismo lipídico (SCD, ME1, FASN, ACACA, LEP, CPT, HADH). Se utilizaron 40 machos Torbiscal que recibieron diferentes dietas: saturada (S), monoinsaturada (M) y poliinsaturada (P). La composición de AG de los tejidos adiposo, hepático y muscular mostró grandes diferencias del grupo P respecto a M y S, que mostraron un perfil similar. La dieta afectó también a la expresión génica en hígado y tejido adiposo, sugiriendo una mayor expresión de enzimas lipogénicas en el grupo M y menor en el P. Estos resultados no explican la mayor capacidad del grupo S para la síntesis endógena de AG, que podría deducirse de los análisis de composición tisular.La composición de los tejidos animales es determinante en la calidad de los productos y está influida por varios factores como la dieta, el tipo genético, la edad y el sexo. En este trabajo se ha evaluado el efecto de la composición de ácidos grasos (AG) de la dieta de cerdos ibéricos en fase de cebo, sobre la composición de AG de los tejidos y la transcripción de genes codificantes para enzimas clave del metabolismo lipídico (SCD, ME1, FASN, ACACA, LEP, CPT, HADH). Se utilizaron 40 machos Torbiscal que recibieron diferentes dietas: saturada (S), monoinsaturada (M) y poliinsaturada (P). La composición de AG de los tejidos adiposo, hepático y muscular mostró grandes diferencias del grupo P respecto a M y S, que mostraron un perfil similar. La dieta afectó también a la expresión génica en hígado y tejido adiposo, sugiriendo una mayor expresión de enzimas lipogénicas en el grupo M y menor en el P. Estos resultados no explican la mayor capacidad del grupo S para la síntesis endógena de AG, que podría deducirse de los análisis de composición tisular