Evaporation and clustering of ammonia droplets in a hot environment

Recent developments in the transition to zero-carbon fuels show that ammonia is a valid candidate for combustion. However, liquid ammonia combustion is difficult to stabilize due to a large latent heat of evaporation, which generates a strong cooling effect that adversely affects the flame stabilization and combustion efficiency. In addition, the slow burning rate of ammonia enhances the undesired production of NOx and N2O. To increase the flame speed, ammonia must be blended with a gaseous fuel having a high burning rate. In this context, a deeper understanding of the droplet dynamics is required to optimize the combustor design. To provide reliable physical insights into diluted ammonia sprays blended with gaseous methane, direct numerical simulations are employed. Three numerical experiments were performed with cold, standard, and hot ambient in nonreactive conditions. The droplet radius and velocity distribution, as well as the mass and heat coupling source terms are compared to study the effects on the evaporation. Since the cooling effect is stronger than the heat convection between the droplet and the environment in each case, ammonia droplets do not experience boiling. On the other hand, the entrainment of dry air into the ammonia-methane mixture moves the saturation level beyond 100% and droplets condense. The aforementioned phenomena are found to strongly affect the droplet evolution. Finally, a three-dimensional Voronoi analysis is performed to characterize the dispersive or clustering behavior of droplets by means of the definition of a clustering index

Photophysical Characterization of Isoguanine in a Prebiotic-Like Environment

It is intriguing how a mixture of organic molecules survived the prebiotic UV fluxes and evolved into the actual genetic building blocks. Scientists are trying to shed light on this issue by synthesizing nucleic acid monomers and their analogues under prebiotic Era-like conditions and by exploring their excited state dynamics. To further add to this important body of knowledge, this study discloses new insights into the photophysical properties of protonated isoguanine, an isomorph of guanine, using steady-state and femtosecond broadband transient absorption spectroscopies, and quantum mechanical calculations. Protonated isoguanine decays in ultrafast time scales following 292 nm excitation, consistently with the barrierless paths connecting the bright S1 (ππ*) state with different internal conversion funnels. Complementary calculations for neutral isoguanine predict similar photophysical properties. These results demonstrate that protonated isoguanine can be considered photostable in contrast to protonated guanine, which exhibits 40-fold longer excited state lifetimesThe authors acknowledge funding from the National Science Foundation (Grant No. CHE-1800052), the Ramón y Cajal Program (Grant: RYC-2016-20489) and the Ministerio de Ciencia, Innovación y Universidades (PGC2018-094644-B-C21, PID2021- 125207NB-C31 and PRE2019-090448 projects). L. M. F. thanks the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with Universidad Autónoma de Madrid in the line Support to Young Researchers, in the context of the V PRICIT (Regional Programme of Research and Technological Innovation) (SI3/PJI/2021-00331

Study of CO2 desublimation during cryogenic carbon capture using the lattice Boltzmann method

Cryogenic carbon capture (CCC) can preferentially desublimate CO2 out of the flue gas. A widespread application of CCC requires a comprehensive understanding of CO2 desublimation properties. This is, however, highly challenging due to the multiphysics behind it. This study proposes a lattice Boltzmann (LB) model to study CO2 desublimation on a cooled cylinder surface during CCC. In two-dimensional (2-D) simulations, various CO2 desublimation and capture behaviours are produced in response to different operation conditions, namely, gas velocity (Péclet number Pe) and cylinder temperature (subcooling degree Tsub). As Pe increases or Tsub decreases, the desublimation rate gradually becomes insufficient compared with the CO2 supply via convection/diffusion. Correspondingly, the desublimated solid CO2 layer (SCL) transforms from a loose (i.e. cluster-like, dendritic or incomplete) structure to a dense one. Four desublimation regimes are thus classified as diffusion-controlled, joint-controlled, convection-controlled and desublimation-controlled regimes. The joint-controlled regime shows quantitatively a desirable CO2 capture performance: fast desublimation rate, high capture capacity, and full cylinder utilization. Regime distributions are summarized on a Pe–Tsub space to determine operation parameters for the joint-controlled regime. Moreover, three-dimensional simulations demonstrate four similar desublimation regimes, verifying the reliability of 2-D results. Under regimes with loose SCLs, however, the desublimation process shows an improved CO2 capture performance in three dimensions. This is attributed to the enhanced availability of gas–solid interface and flow paths. This work develops a reliable LB model to study CO2 desublimation, which can facilitate applications of CCC for mitigating climate change

Targeted-release organic acids and essential oils improve performance and digestive function in broilers under a necrotic enteritis challenge

An experiment was performed to evaluate the effect of four different microencapsulated blends of organic acids (OA) and nature-identical aromatic compounds (AC) on growth performance and gut health of broilers challenged with a recycled NE litter. A total of 600 one-day-old male Ross 308 broilers were randomly assigned to five treatments consisting of a basal diet (as negative control) supplemented with each of the tested microencapsulated blends: OA1 (malic and fumaric acid) + AC; 2.5 g/kg; OA2 (calcium butyrate+fumaric acid) + AC; 1.7 g/kg; MCFA (capric-caprylic; caproic and lauric acid) + AC; 2 g/kg; and MCFA + OA3(calcium butyrate + fumaric and citric acid) + AC; 1.5 g/kg. The AC used was the same for all treatments; including cinnamaldehyde, carvacrol, and thymol (8:1:1), as major compounds. Three tested blends enhanced growth performance by improving intestinal histomorphology (p < 0.001). The tested blends enhanced the abundance of some beneficial families such as Ruminococcaceae and Lachnospiraceae; while reducing that of harmful ones such as Enterobacteriaceae and Helicobacteraceae. A further dose-response experiment showed that 0.5 g/kg of the blend 2 and 2 g/kg of the blend 4 improved growth performance and intestinal histomorphology of chickens on d 42 and decreased fecal Enterobacteriaceae and C. perfringens counts. Similar effects to the previous experiment were observed for cecum microbiota

Intensive Habitat Loss in South Spain: Arborescent Scrubs with <em>Ziziphus</em> (5220*)

The habitat arborescent matorral with Ziziphus (5220*) was included in the Habitats Directive of the European Commission. These plant formations represent the maximum potential vegetation in a very restrictive arid environment, since it encompasses endemic, tropical, or Maghrebian floristic elements, and from other areas of the ancient Thetis Sea. In fact, the version of this community with Gymnosporia senegalensis (Lam.) Loes. [=Maytenus senegalensis (Lam.) Exell] constitutes extraordinarily singular flora formations in the Iberian southeast. These are unique communities in Europe and ecologically extremely valuable and, however, have been included among the Europe’s most endangered habitats. The vast economic development experienced in South Spain based on the remarkable transformation of traditional farming patterns into a highly profitable agriculture that uses industrial production methods and the groundwater intensively (agriculture intensification and land-use change), in addition to urbanization without sustainable land planning, determines that European G. senegalensis populations are seriously threatened by severe habitat destruction and fragmentation

Lattice dynamics of Sb2Te3 at high pressures

We report an experimental and theoretical lattice dynamics study of antimony telluride (Sb 2Te 3) up to 26 GPa together with a theoretical study of its structural stability under pressure. Raman-active modes of the low-pressure rhombohedral (R-3m) phase were observed up to 7.7 GPa. Changes of the frequencies and linewidths were observed around 3.5 GPa where an electronic topological transition was previously found. Raman-mode changes evidence phase transitions at 7.7, 14.5, and 25GPa. The frequencies and pressure coefficients of the new phases above 7.7 and 14.5 GPa agree with those calculated for the monoclinic C2/m and C2/c structures recently observed at high pressures in Bi 2Te 3 and also for the C2/m phase in the case of Bi 2Se 3 and Sb 2Te 3. Above 25 GPa no Raman-active modes are observed in Sb 2Te 3, similarly to the case of Bi 2Te 3 and Bi 2Se 3. Therefore, it is possible that the structure of Sb 2Te 3 above 25 GPa is the same disordered bcc phase already found in Bi 2Te 3 by x-ray diffraction studies. Upon pressure release, Sb 2Te 3 reverts back to the original rhombohedral phase after considerable hysteresis. Raman- and IR-mode symmetries, frequencies, and pressure coefficients in the different phases are reported and discussed. © 2011 American Physical Society.This work has been done under financial support from Spanish MICINN under Project Nos. MAT2010-21270-C04-03/04 and CSD-2007-00045 and supported by the Ministry of Education, Youth and Sports of the Czech Republic (MSM 0021627501). E. P.-G. acknowledges the financial support of the Spanish MEC under a FPI fellowship. Supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster.Gomis Hilario, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.; Rodríguez-Hernández, P.; Pérez-González, E.; Muñoz, A.; Kucek, V.... (2011). 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V., Sharp, J., & Badding, J. V. (2001). Large Improvement in Thermoelectric Properties in Pressure-Tuned p-Type Sb1.5Bi0.5Te3. Chemistry of Materials, 13(6), 2068-2071. doi:10.1021/cm000888qChandra Shekar, N. V., Polvani, D. A., Meng, J. F., & Badding, J. V. (2005). Improved thermoelectric properties due to electronic topological transition under high pressure. Physica B: Condensed Matter, 358(1-4), 14-18. doi:10.1016/j.physb.2004.12.020Ovsyannikov, S. V., Shchennikov, V. V., Vorontsov, G. V., Manakov, A. Y., Likhacheva, A. Y., & Kulbachinskii, V. A. (2008). Giant improvement of thermoelectric power factor of Bi2Te3 under pressure. Journal of Applied Physics, 104(5), 053713. doi:10.1063/1.2973201Ovsyannikov, S. V., & Shchennikov, V. V. (2010). High-Pressure Routes in the Thermoelectricity or How One Can Improve a Performance of Thermoelectrics†. Chemistry of Materials, 22(3), 635-647. doi:10.1021/cm902000xLi, C., Ruoff, A. L., & Spencer, C. W. (1961). Effect of Pressure on the Energy Gap of Bi2Te3. Journal of Applied Physics, 32(9), 1733-1735. doi:10.1063/1.1728426Khvostantsev, L. G., Orlov, A. I., Abrikosov, N. K., & Ivanova, L. D. (1980). Thermoelectric properties and phase transition in Sb2Te3 under hydrostatic pressure up to 9 GPa. Physica Status Solidi (a), 58(1), 37-40. doi:10.1002/pssa.2210580103Sakai, N., Kajiwara, T., Takemura, K., Minomura, S., & Fujii, Y. (1981). Pressure-induced phase transition in Sb2Te3. Solid State Communications, 40(12), 1045-1047. doi:10.1016/0038-1098(81)90248-9Khvostantsev, L. G., Orlov, A. I., Abrikosov, N. K., & Ivanova, L. D. (1985). Kinetic Properties and Phase Transitions in Sb2Te3 under Hydrostatic Pressure up to 9 GPa. physica status solidi (a), 89(1), 301-309. doi:10.1002/pssa.2210890132Thonhauser, T., Scheidemantel, T. J., Sofo, J. O., Badding, J. V., & Mahan, G. D. (2003). Thermoelectric properties ofSb2Te3under pressure and uniaxial stress. Physical Review B, 68(8). doi:10.1103/physrevb.68.085201Thonhauser, T. (2004). Influence of negative pressure on thermoelectric properties of Sb2Te3. Solid State Communications, 129(4), 249-253. doi:10.1016/j.ssc.2003.10.006Einaga, M., Tanabe, Y., Nakayama, A., Ohmura, A., Ishikawa, F., & Yamada, Y. (2010). New superconducting phase of Bi2Te3under pressure above 11 GPa. Journal of Physics: Conference Series, 215, 012036. doi:10.1088/1742-6596/215/1/012036Zhang, J. L., Zhang, S. J., Weng, H. M., Zhang, W., Yang, L. X., Liu, Q. Q., … Jin, C. Q. (2010). Pressure-induced superconductivity in topological parent compound Bi2Te3. Proceedings of the National Academy of Sciences, 108(1), 24-28. doi:10.1073/pnas.1014085108Jacobsen, M. K., Kumar, R. S., Cornelius, A. L., Sinogeiken, S. V., Nico, M. F., Elert, M., … Nguyen, J. (2008). HIGH PRESSURE X-RAY DIFFRACTION STUDIES OF Bi[sub 2−x]Sb[sub x]Te[sub 3] (x = 0,1,2). doi:10.1063/1.2833001Nakayama, A., Einaga, M., Tanabe, Y., Nakano, S., Ishikawa, F., & Yamada, Y. (2009). Structural phase transition in Bi2Te3 under high pressure. High Pressure Research, 29(2), 245-249. doi:10.1080/08957950902951633Einaga, M., Ohmura, A., Nakayama, A., Ishikawa, F., Yamada, Y., & Nakano, S. (2011). Pressure-induced phase transition of Bi2Te3to a bcc structure. Physical Review B, 83(9). doi:10.1103/physrevb.83.092102Zhu, L., Wang, H., Wang, Y., Lv, J., Ma, Y., Cui, Q., … Zou, G. (2011). Substitutional Alloy of Bi and Te at High Pressure. Physical Review Letters, 106(14). doi:10.1103/physrevlett.106.145501Itskevich, E. S., Kashirskaya, L. M., & Kraidenov, V. F. (1997). Anomalies in the low-temperature thermoelectric power of p-Bi2Te3 and Te associated with topological electronic transitions under pressure. Semiconductors, 31(3), 276-278. doi:10.1134/1.1187126Polian, A., Gauthier, M., Souza, S. M., Trichês, D. M., Cardoso de Lima, J., & Grandi, T. A. (2011). Two-dimensional pressure-induced electronic topological transition in Bi2Te3. Physical Review B, 83(11). doi:10.1103/physrevb.83.113106Vilaplana, R., Santamaría-Pérez, D., Gomis, O., Manjón, F. J., González, J., Segura, A., … Kucek, V. (2011). Structural and vibrational study of Bi2Se3under high pressure. Physical Review B, 84(18). doi:10.1103/physrevb.84.184110Richter, W., & Becker, C. R. (1977). A Raman and far-infrared investigation of phonons in the rhombohedral V2–VI3 compounds Bi2Te3, Bi2Se3, Sb2Te3 and Bi2(Te1−xSex)3 (0 <x < 1), (Bi1−ySby)2Te3 (0 <y < 1). Physica Status Solidi (b), 84(2), 619-628. doi:10.1002/pssb.2220840226Sosso, G. C., Caravati, S., & Bernasconi, M. (2009). Vibrational properties of crystalline Sb2Te3from first principles. Journal of Physics: Condensed Matter, 21(9), 095410. doi:10.1088/0953-8984/21/9/095410Dagens, L. (1978). Phonon anomaly near a Fermi surface topological transition. Journal of Physics F: Metal Physics, 8(10), 2093-2113. doi:10.1088/0305-4608/8/10/010Dagens, L., & Lopez-Rios, C. (1979). Thermodynamic properties of a metal near a Fermi surface topological transition: the anomalous electron-phonon interaction contribution. Journal of Physics F: Metal Physics, 9(11), 2195-2216. doi:10.1088/0305-4608/9/11/011Goncharov, A. ., & Struzhkin, V. . (2003). Pressure dependence of the Raman spectrum, lattice parameters and superconducting critical temperature of MgB2: evidence for pressure-driven phonon-assisted electronic topological transition. Physica C: Superconductivity, 385(1-2), 117-130. doi:10.1016/s0921-4534(02)02311-0Antonangeli, D., Farber, D. L., Said, A. H., Benedetti, L. R., Aracne, C. M., Landa, A., … Klepeis, J. E. (2010). Shear softening in tantalum at megabar pressures. Physical Review B, 82(13). doi:10.1103/physrevb.82.132101Santamaría-Pérez, D., Vegas, A., Muehle, C., & Jansen, M. (2011). Structural behaviour of alkaline sulfides under compression: High-pressure experimental study on Cs2S. The Journal of Chemical Physics, 135(5), 054511. doi:10.1063/1.3617236Vilaplana, R., Gomis, O., Manjón, F. J., Segura, A., Pérez-González, E., Rodríguez-Hernández, P., … Kucek, V. (2011). High-pressure vibrational and optical study of Bi2Te3. Physical Review B, 84(10). doi:10.1103/physrevb.84.104112Larson, P. (2006). Effects of uniaxial and hydrostatic pressure on the valence band maximum inSb2Te3: An electronic structure study. Physical Review B, 74(20). doi:10.1103/physrevb.74.205113Lošťák, P., Beneš, L., Civiš, S., & Süssmann, H. (1990). Preparation and some physical properties of Bi2−xInxSe3 single crystals. Journal of Materials Science, 25(1), 277-282. doi:10.1007/bf00544220Horák, J., Quayle, P. C., Dyck, J. S., Drašar, Č., Lošt’ák, P., & Uher, C. (2008). Defect structure of Sb2−xCrxTe3 single crystals. Journal of Applied Physics, 103(1), 013516. doi:10.1063/1.2826940Piermarini, G. J., Block, S., & Barnett, J. D. (1973). Hydrostatic limits in liquids and solids to 100 kbar. Journal of Applied Physics, 44(12), 5377-5382. doi:10.1063/1.1662159Errandonea, D., Meng, Y., Somayazulu, M., & Häusermann, D. (2005). Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress. Physica B: Condensed Matter, 355(1-4), 116-125. doi:10.1016/j.physb.2004.10.030Syassen, K. (2008). Ruby under pressure. High Pressure Research, 28(2), 75-126. doi:10.1080/08957950802235640Hohenberg, P., & Kohn, W. (1964). Inhomogeneous Electron Gas. Physical Review, 136(3B), B864-B871. doi:10.1103/physrev.136.b864Kresse, G., & Hafner, J. (1993). Ab initiomolecular dynamics for liquid metals. Physical Review B, 47(1), 558-561. doi:10.1103/physrevb.47.558Kresse, G., & Hafner, J. (1994). Ab initiomolecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium. Physical Review B, 49(20), 14251-14269. doi:10.1103/physrevb.49.14251Kresse, G., & Furthmüller, J. (1996). Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Computational Materials Science, 6(1), 15-50. doi:10.1016/0927-0256(96)00008-0Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Perdew, J. P., Ruzsinszky, A., Csonka, G. I., Vydrov, O. A., Scuseria, G. E., Constantin, L. A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Mujica, A., Rubio, A., Muñoz, A., & Needs, R. J. (2003). High-pressure phases of group-IV, III–V, and II–VI compounds. Reviews of Modern Physics, 75(3), 863-912. doi:10.1103/revmodphys.75.863Blanco, M. A., Francisco, E., & Luaña, V. (2004). GIBBS: isothermal-isobaric thermodynamics of solids from energy curves using a quasi-harmonic Debye model. Computer Physics Communications, 158(1), 57-72. doi:10.1016/j.comphy.2003.12.001Cardona, M. (2004). Phonon widths versus pressure. High Pressure Research, 24(1), 17-23. doi:10.1080/08957950310001635819Cardona, M. (2004). Effects of pressure on the phonon–phonon and electron–phonon interactions in semiconductors. physica status solidi (b), 241(14), 3128-3137. doi:10.1002/pssb.200405202Ulrich, C., Mroginski, M. A., Goñi, A. R., Cantarero, A., Schwarz, U., Muñoz, V., & Syassen, K. (1996). Vibrational Properties of InSe under Pressure: Experiment and Theory. physica status solidi (b), 198(1), 121-127. doi:10.1002/pssb.2221980117Kulibekov, A. M., Olijnyk, H. P., Jephcoat, A. P., Salaeva, Z. Y., Onari, S., & Allakhverdiev, K. R. (2003). Raman scattering under pressure and the phase transition in ɛ-GaSe. physica status solidi (b), 235(2), 517-520. doi:10.1002/pssb.200301613Cheng, W., & Ren, S.-F. (2011). Phonons of single quintuple Bi2Te3and Bi2Se3films and bulk materials. Physical Review B, 83(9). doi:10.1103/physrevb.83.094301Buga, S. G., Serebryanaya, N. R., Dubitskiy, G. A., Semenova, E. E., Aksenenkov, V. V., & Blank, V. D. (2011). Structure and electrical properties of Sb2Te3and Bi0.4Sb1.6Te3metastable phases obtained by HPHT treatment. High Pressure Research, 31(1), 86-90. doi:10.1080/08957959.2010.52342

Behavior analysis of real wages in Mexico (1995-2018)

Objective: To determine through econometric analysis which variables —inflation, real exchange rate, unemployment, and consumption— have a major impact on workers' wages and, therefore, on production. Design/Methodology/Approach: We developed a multiple linear regression model for the behavior of macroeconomic variables in Mexico from 1995 to 2018, using the ordinary least squares method (OLS) and the Gretl statistical package. Results: The analysis of the model showed that inflation, exchange rate, and unemployment are highly significant, unlike consumption. For the model of real wages in Mexico, we obtained a 0.87 coefficient of determination —i.e., the variables included in the model account for 87% of the wages’ behavior. The relation of consumption, unemployment, and inflation to wages was as expected. Regarding the exchange rate, the result was the opposite of the expectations. The wage-unemployment elasticity had the greatest impact. Study Limitations/Implications: The database used was the main limitation because it relies on official sources, which lack data and show inconsistencies. Findings/Conclusions: The study helped to determine whether or not the proposed variables affected the national economic growth. Mexico is not a first-world country than can offer high salaries; therefore, the Mexican economy must continue to grow, before it reaches a higher per capita income. In this regard, it is essential to consider the extent to which the new government’s proposals will be able to face the reality: very few and very low-quality jobs are created, despite what the official figures say

Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure

[EN] This paper reports an experimental and theoretical investigation on the electronic structure of bismuth selenide (Bi2Se3) up to 9 GPa. The optical gap of Bi2Se3 increases from 0.17 eV at ambient pressure to 0.45 eV at 8 GPa. The quenching of the Burstein-Moss effect in degenerate samples and the shift of the free-carrier plasma frequency to lower energies reveal a quick decrease of the bulk three-dimensional (3D) electron concentration under pressure. On increasing pressure the behavior of Hall electron concentration and mobility depends on the sample thickness, consistently with a gradual transition from mainly 3D transport at ambient pressure to mainly two-dimensional (2D) transport at high pressure. Two-carrier transport equations confirm the trapping of high-mobility 3D electrons, an effect that can be related to a shallow-to-deep transformation of donor levels, associated with a change in the ordering of the conduction band minima. The high apparent areal density and low electron mobility of 2D electrons are not compatible with their expected properties in a Dirac cone. Measured transport parameters at high pressure are most probably affected by the presence of holes, either in an accumulation surface layer or as minority carriers in the bulk. ©2012 American Physical SocietyThis work has been done under financial support from Spanish MICINN under Grants No. MAT2008-06873-C02-02, No. MAT2007-66129, No. MAT2010-21270-C04-03/04, No. CSD2007-00045, and Prometeo No. GV2011/035. The supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster.Segura, A.; Panchal, V.; Sánchez-Royo, JF.; Marín-Borrás, V.; Muñoz-Sanjosé, V.; Rodríguez-Hernández, P.; Muñoz, A.... (2012). Trapping of three-dimensional electrons and transition to two-dimensional transport in the three-dimensional topological insulator Bi2Se3 under high pressure. 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