Study of a Coke Can as a rocket structure and its flutter effects

This final bachelor work (TFC) is a study of a Coke Can properties to be reused in a rocket as a structure. The work is focused in the possible flutter effects that this structure could present. There are two main blocks to achieve: First block is a good proposed structure model. Second block is a good internal rocket flow model. For this reason, two students are required. First block studies the Coke Can behaviour in terms of weak structural points (Crack propagation, flanges, bulkhead). Some pressure test will be done. Because this structure will have a very high thermal load, the steel material study is required. In addition, the solid propellant (APCP or Candy) inside the rocket structure should be taken into account. Second block studies the flow inside the combustion chamber in order to find weak points, the pressure field, the temperature field and speed field. Also it is required to know the flow behaviour in the nozzle. Some SolidWorks simulations in terms of Computed Fluid Dynamics (CFD) should be done. In addition, structural elastic studies will provide the oscillation modes. It is necessary to know if the flow will generate resonant frequencies that are in the range of the structural oscillation modes.Aquest treball final de carrera (TFC) és un estudi de les propietats d'una llauna de refresc per ser reutilitzada com estructura per a un coet. El treball se centra en els possibles efectes de fluctuació que aquesta estructura podria presentar. Es compon de dos grans blocs: El primer bloc és un bon model de l'estructura proposada. El segon bloc és un bon model intern del flux en el coet. Per aquesta raó, es requereixen dos estudiants. El primer bloc estudia una llauna de Coca Cola tipu s i el seu comportament quant a punts febles estructurals (Propagació d'esq uerdes, brides i tancament). Es realitzen algunes proves de pressió. A causa de que aquesta estructura tindrà una càrrega tèrmica molt alta, es realitza un estudi del material, que és acer. A més es té en compte el com bustible sòlid (APCP o Candy) que porti dins de l'estructura del coet. El segon estudi estudia el flux a l'interior de la cambra de combustió a fi de trobar punts febles, camp de pressions, camps de te mperatures i el camp de velocitats. També s'estudia el comportament del flu x en la gola. Es realitzen algunes simulacions de SolidWorks calculades en ter mes de dinàmica de fluids (CFD). A més, s'estudia el comportament elàs tic de l'estructura i els modes d'oscil·lació. Finalment s'esbrina si el flux generarà freqüències de ressonància que es trobin en el rang dels modes d'o scil·lació estructurals

Interferometric measurement of interhyperfine scattering lengths in 87^{87}Rb

We present interferometeric measurements of the $f=1$ to $f=2$ inter-hyperfine scattering lengths in a single-domain spinor Bose-Einstein condensate of $^{87}$Rb. The inter-hyperfine interaction leads to a strong and state-dependent modification of the spin-mixing dynamics with respect to a non-interacting description. We employ hyperfine-specific Faraday-rotation probing to reveal the evolution of the transverse magnetization in each hyperfine manifold for different state preparations, and a comagnetometer strategy to cancel laboratory magnetic noise. The method allows precise determination of inter-hyperfine scattering length differences, calibrated to intra-hyperfine scattering length differences. We report $(a_{3}^{(12)}-a_{2}^{(12)})/(a_{2}^{(1)}-a_{0}^{(1)})=-1.27(15)$ and $(a_{1}^{(12)}-a_{2}^{(12)})/(a_{2}^{(1)}-a_{0}^{(1)})=-1.31(13)$, limited by atom number uncertainty. With achievable control of atom number, we estimate precisions of $\approx 0.3\%$ should be possible with this technique

Bose-Einstein Condensate Comagnetometer

We describe a comagnetometer employing the $f=1$ and $f=2$ ground state hyperfine manifolds of a $^{87}$Rb spinor Bose-Einstein condensate as co-located magnetometers. The hyperfine manifolds feature nearly opposite gyromagnetic ratios and thus the sum of their precession angles is only weakly coupled to external magnetic fields, while being highly sensitive to any effect that rotates both manifolds in the same way. The $f=1$ and $f=2$ transverse magnetizations and azimuth angles are independently measured by non-destructive Faraday rotation probing, and we demonstrate a $44.0(8)\text{dB}$ common-mode rejection in good agreement with theory. We show how spin-dependent interactions can be used to inhibit $2\rightarrow 1$ hyperfine relaxing collisions, extending to $\sim 1\text{s}$ the transverse spin lifetime of the $f=1,2$ mixtures. The technique could be used in high sensitivity searches for new physics on sub-millimeter length scales, precision studies of ultra-cold collision physics, and angle-resolved studies of quantum spin dynamics

Enhancement of interfacial adhesion between starch and graftedpoly(epsilon-caprolactone)

[EN] The use of a modified poly(Epsilon-caprolactone) (gPCL) to enhance polymer miscibility in films based on ther-moplastic starch (S) and poly(Epsilon-caprolactone) is reported. PCL was functionalized by grafting with maleicanyhdride (MA) and/or glycidyl methacrylate (GMA) by reactive blending in a batch mixer. gPCL basedmaterials were analysed in terms of their grafting degree, structural and thermal properties. Blends basedon starch and PCL (wt. ratio 80:20) with including gPCL (0, 2.5 and 5 wt.%), as a compatibilizer, wereobtained by extrusion and compression moulding, and their structural, thermal, mechanical and bar-rier properties were investigated. Blends containing gPCL evidenced better interfacial adhesion betweenstarch and PCL domains, as deduced from both structural (XRD, FTIR, SEM) and bulk properties (DSC, TGA).Moreover, grafted PCL-based compatibilizers greatly improved functional properties of S-PCL blend films,as pointed out from mechanical performance and higher barrier properties, valuable to meet the foodpackaging requirements.The authors gratefully acknowledge the project MAREA, "Materiali Avanzati per la Ricerca ed il comparto Agroalimentare"-in the frame of National Operative Program (PON 2007-2013) and Ministerio de Economia y Competitividad (Spain) throughout the project AGL2013-42989 for their research financial support. They would like to thank the laboratory of electron microscopy "LaMEST" CNR, in the person of Maria Cristina Del Barone for the kind technical assistance in performing SEM analysis. R. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolia grant (GRISOLIA 2012/001) and to Short-Term Scientific Missions (STSM) from European Cooperation in Science and Technology (COST).Ortega-Toro, R.; Santagata, G.; D Ayala, GG.; Cerruti, P.; Talens Oliag, P.; Chiralt, A.; Malinconico, M. (2016). Enhancement of interfacial adhesion between starch and graftedpoly(epsilon-caprolactone). Carbohydrate Polymers. 147:16-27. https://doi.org/10.1016/j.carbpol.2016.03.070S162714

High-fidelity trajectory design to flyby near-Earth asteroids using CubeSats

Fast development of CubeSat technology now enables the first interplanetary missions. The potential application of CubeSats to flyby near-Earth asteroids is explored in this paper in consideration of CubeSats' limited propulsive capabilities and systems constraints. Low-energy asteroid flyby trajectories are designed assuming a CubeSat is initially parked around to the Sun-Earth Lagrange points. High-impulse and low-thrust trajectories with realistic thrusting models are computed first in the Circular Restricted Three-Body Problem (CR3BP), and then in a high-fidelity ephemeris model. Analysis in the ephemeris model is used to confirm that trajectories computed in the CR3BP model also exist in a more realistic dynamical model, and to verify the validity of the results obtained in CR3BP analysis. A catalogue of asteroid flyby opportunities between years 2019 and 2030 is provided, with 80 m/s of available ΔV and departure from halo orbits around the first and second Sun-Earth Lagrange points (of similar size to those typically used by scientific missions). Results show that the CR3BP model can serve as an effective tool to identify reachable asteroids and can provide an initial estimation of the ΔV cost in the ephemeris model (with ±15 m/s accuracy). An impulsive maneuver model can also provide an accurate estimation of the ΔV requirement for a CubeSat equipped with a high-impulse thruster (with 4 m/s accuracy), even if its thrust magnitude is small and requires duty cycling; low-thrust ΔV requirements, however, may differ significantly from the impulsive results (±15 m/s)

Redefining biomaterial biocompatibility: challenges for artificial intelligence and text mining

The surge in ‘Big data’ has significantly influenced biomaterials research and development, with vast data volumes emerging from clinical trials, scientific literature, electronic health records, and other sources. Biocompatibility is essential in developing safe medical devices and biomaterials to perform as intended without provoking adverse reactions. Therefore, establishing an artificial intelligence (AI)-driven biocompatibility definition has become decisive for automating data extraction and profiling safety effectiveness. This definition should both reflect the attributes related to biocompatibility and be compatible with computational data-mining methods. Here, we discuss the need for a comprehensive and contemporary definition of biocompatibility and the challenges in developing one. We also identify the key elements that comprise biocompatibility, and propose an integrated biocompatibility definition that enables data-mining approaches.Peer ReviewedPostprint (published version

Community-acquired pneumonia in hospitalised patients: changes in aetiology, clinical presentation, and severity outcomes in a 10-year period

Staphylococcus aureus; Mortality; VirologyStaphylococcus aureus; Mortalidad; VirologíaStaphylococcus aureus; Mortalitat; VirologiaBackground and objective Community-acquired pneumonia (CAP) is a frequent cause of hospitalisation. Several factors, such as pandemics, vaccines and globalisation may lead to changes in epidemiology, clinical presentation, and outcomes of CAP, which oblige to a constant actualisation. We performed this study to analyse how these factors have evolved over a 10-year period. Materials and methods Patients diagnosed with CAP for two 1-year periods that were 10 years apart (2007–2008 and 2017–2018) were included. We compared microbiological information, clinical data and evolutive outcomes in the two periods. A mortality analysis was performed. Results 1043 patients were included: 452 during the first period (2007- 2008), and 591 during the second period (2017–2018). Bacterial aetiology did not change during the 10-year period, besides a slight increase in Staphylococcus aureus (0.9% vs 2.9%, p = 0.026). There was a decline in the proportion of bacteraemia in the second period (14.8% vs 9.6%, p = 0.012). The incidence of complicated pleural effusion and septic shock declined too (6.4% vs 3.6%, p = 0.04 and 15.5% vs 6.3%, p < 0.001). Respiratory failure and Intensive care unit (ICU) admission were similar in both periods. Variables independently associated with mortality were age and septic shock. Influenza vaccine was a protective factor against mortality in the second period. Conclusions We have not found relevant differences in the bacterial aetiology of CAP over this 10-year period. There has been a decline in septic complications of CAP such as septic shock, bacteraemia, and complicated pleural effusion. Influenza vaccination is an important tool to reduce mortality

Insights into Structure-Activity Relationships of Somatostatin Analogs Containing Mesitylalanine.

The non-natural amino acid mesitylalanine (2,4,6-trimethyl-L-phenylalanine; Msa) has an electron-richer and a more conformationally restricted side-chain than that of its natural phenylalanine counterpart. Taking these properties into account, we have synthesized ten somatostatin analogs containing Msa residues in different key positions to modify the intrinsic conformational flexibility of the natural hormone. We have measured the binding affinity of these analogs and correlated it with the main conformations they populate in solution. NMR and computational analysis revealed that analogs containing one Msa residue were conformationally more restricted than somatostatin under similar experimental conditions. Furthermore, we were able to characterize the presence of a hairpin at the pharmacophore region and a non-covalent interaction between aromatic residues 6 and 11. In all cases, the inclusion of a D-Trp in the eighth position further stabilized the main conformation. Some of these peptides bound selectively to one or two somatostatin receptors with similar or even higher affinity than the natural hormone. However, we also found that multiple incorporations of Msa residues increased the life span of the peptides in serum but with a loss of conformational rigidity and binding affinity