Aconsegueixen desplaçar objectes nanomètrics mitjançant canvis de temperatura

A través d'un nanotub multicapa de carboni s'ha demostrat que l'origen directe del moviment d'un objecte mòbil es troba en l'heterogeneïtat tèrmica d'aquest tub. Apareix quan flueix un corrent elèctric per l'interior del tub conductor -amb el seu corresponent escalfament- i els dos electrodes dels seus extrems estan a temperatura ambient

First-principles simulations of lithium melting: Stability of the bcc phase close to melting

4 páginas, 2 figuras.We report large-scale first-principles simulations of melting of four different phases of Li at pressures ranging from 0 to 50 GPa. We find excellent agreement with existing experimental data at low pressures, and confirm that above 10 GPa the melting line develops a negative slope, in parallel to what occurs for Na at 30 GPa. Surprisingly, our results indicate that the melting temperature of the bcc phase is always higher than that of fcc Li, suggesting the intriguing possibility of the existence of a narrow field of bcc stability separating the fcc and liquid phases, as predicted by Alexander and McTague.The work of E. R. H. is supported by the Spanish Ministry of Science and Innovation through Project No. FIS2006-12117-C04-01; A. B. thanks GV-UPV/EHU for Project No. IT-366-07. The work of D. A. was conducted as part of an EURYI scheme grant as provided by EPSRC-GB.Peer reviewe

Behavior of Clayey Soil Existing in the Portoviejo Canton and Its Neutralization Characteristics

An investigation has been carried out on soil characterization and behavior in the canton of Portoviejo province of Manabí, in the Eloy Alfaro street sector of the Andrés de Vera Parish; where pits or open-air surveys were carried out and experimental laboratory tests of soils. It was demonstrated that soils have expansive properties of different characteristics, from medium to high degree of expansively according to the results of Laboratory of Soil Mechanics, where samples were tested analyzing the behavior according to the soil type. In this context, the results obtained by incorporating lime into the mixture are presented in 3 and 6%, thus obtaining a reduction by contraction to the volumetric change of the soil between 8 and 13%, allowing to improve its physical and mechanical properties; as well as its increase to bearing capacity by the California Bearing Ratio (CBR) test method from 9 to 16%, thus improving soil plasticity. With the results obtained, a description of the soil could be elaborated to determine the variations and changes according to the lime content, which was added to the soil, which allowed to reduce the deformations and damages caused to the superficial and structural pavement caused by the clays expansive, because in contact with the water the soil expands and at the same time when it drains the water contracts, proving that stabilizing the expansive clays with hydrated lime would improve the conditions of the pavement and its useful life

Hydrogen and muonium in diamond: A path-integral molecular dynamics simulation

Isolated hydrogen, deuterium, and muonium in diamond have been studied by path-integral molecular dynamics simulations in the canonical ensemble. Finite-temperature properties of these point defects were analyzed in the range from 100 to 800 K. Interatomic interactions were modeled by a tight-binding potential fitted to density-functional calculations. The most stable position for these hydrogenic impurities is found at the C-C bond center. Vibrational frequencies have been obtained from a linear-response approach, based on correlations of atom displacements at finite temperatures. The results show a large anharmonic effect in impurity vibrations at the bond center site, which hardens the vibrational modes with respect to a harmonic approximation. Zero-point motion causes an appreciable shift of the defect level in the electronic gap, as a consequence of electron-phonon interaction. This defect level goes down by 70 meV when replacing hydrogen by muonium.Comment: 11 pages, 8 figure

Segregation of equal-sized particles of different densities in a vertically vibrated fluidized bed

Proceeding of: Fifteenth International Conference on Fluidization, Fluidization XV, Fluidization for Emerging Green Technologies, Montebello, Canada, May 22nd to 27th, 2016The present work experimentally studies the influence of vibration and gas velocity on the density-induced segregation of particles in a pseudo-2D vibrated fluidized bed. One half of the particles of the bed are ballotini spheres of density 2500 kg/m(3) and the other half are heavier ceramic particles of density 4100 kg/m(3) or 6000 kg/m(3). Digital Image Analysis is used to characterize the rate and extent of particle mixing with time for different gas velocities, vibration amplitudes and frequencies. The results of the experiments indicate that the vibration strength and the gas velocity have an important effect on both the evolution and the final extent of density-induced particle segregation. It was observed that by introducing vertical vibration to a bed that is fluidized close to minimum fluidization conditions the rate of segregation and the final segregation index of a mixture of light and dense particles is enhanced. However, for vibration strengths greater than a critical value around 3-4, the degree of segregation decreases due to a more vigorous three dimensional mixing of particles in the bed.This work has been partially funded by the Universidad Carlos III de Madrid (Ayudas a la movilidad 2015) and by the Spanish Ministry of Economy and Competiveness (project ENE2015/00188/001)

Theoretical evidence for the kick-out mechanism for B diffusion in SiC

In this letter, we analyze by means of first-principles electronic structure calculations the diffusion of B impurities in 3C-SiC. We find, through molecular dynamics, that substitutional B at a Si lattice site is readily displaced by a nearby Si interstitial by the process known as a kick-out mechanism, in agreement with recent experimental results. This is in contrast to the situation in Si, where B has recently been shown to diffuse via an interstitialcy mechanism

HER1 therapeutic cancer vaccine: An active immunotherapy treatment for patients with tumors expressing the receptor of epidermal growth factor (EGF-R)

Her1 vaccine: It consists of immunizing patients with positive tumors for the epidermal growth factor receptor (EGF-R) with a preparation of EGF-R extracellular domain(HER1-ECD) adjuvanted in VSSP (very small size proteoliposomes) and Montanide ISA51. VSSP adyuvant confers to vaccine the capacity to activate dendritic cells and polarize the immune response towards a TH1 immune pattern, developing TCD8+ cells and antibodies with anti-metastatic effect. The extracellular domain of the epidermal growth factor receptor was obtained from HEK293 transfectome by using a productive process in a bioreactor in perfusion as mode of fermentation. The protein was purified by immune-affinity chromatography by using specific anti-EGF-R antibody. Phase I trial, uncontrolled, open and sequential, was conducted in 25 with hormone refractory prostate cancer patients. Five dose levels of HER1-ECD were scaled: 100, 200, 400, 600 and 800 µg in each immunization. The trial showed that the vaccine was safe, not causing severe or very severe related events. The vaccine preparation was shown to be immunogenic. There was a trend towards the survival benefit in some patients. At the present time another clinical trial is underway in three locations of advanced solid tumors that overexpress the EGF receptor: prostate, colon and head and neck cancer

Use of Concrete Debris

Natural disasters in a very short time are capable of destroying what man has built using different types of resources, the construction of buildings, houses, etc. In their construction processes, they use different materials in a separate way that mixes and this process give them hardness and resistance to these materials. When they are destroyed they lose their individual properties and become waste; this research aims to make a study of the NEVI-12-MTOP standards, to be able to reuse the debris materials generated by the destruction of the earthquake on April 16. A bibliographic search was carried out related to the use given to waste caused by earthquakes in different countries. In the city of Portoviejo, the largest amount of debris was a concrete waste, and it can be concluded that these materials can be used as sub-base material in the road structures, so the reuse method was proposed. In particular, the characteristics of the residual materials were obtained as a result of the analysis of environmental, economic and material safety feasibility

Theoretical characterization of several models of nanoporous carbon

"Elastic, electronic and vibrational properties of seven models of nanoporous carbon are reported. The studied structures are periodic graphitic arrangements with heptagonal and octagonal rings of carbon, known as Schwarzites. The calculations were performed within a non-orthogonal tight binding framework which has been shown to be reliable for diamond, graphene layers, fullerenes and carbon nanotubes. In contrast with previous studies, each structure was properly relaxed, so that differences between each model must be assigned to intrinsic properties rather than to differences in their construction. Thermodynamic properties were calculated from the vibrational density of states.